Split (3)

train · 130k rows

description stringlengths 2.98k 3.35M	abstract stringlengths 94 10.6k	cpc int64 0 8
FIELD OF THE INVENTION The invention relates to a spring wire ski brake comprising two braking mandrels which project in the braking position next to the two lateral edges of the ski below the bottom surface of the ski, which braking mandrels are the free ends of a braking bar which is formed of the spring wire by repeatedly bending the wire, which braking bar can be pivoted into a retracted position about an axis which lies substantially at a right angle with respect to the longitudinal axis of the ski against the self-contained torsional force by means of a ski boot or by means of a sole plate or the like, and in which position the braking mandrels are held above and approximately parallel with respect to the upper side of the ski and the braking bar has two pivot axles which lie spaced from one another in the longitudinal direction of the ski, of which one of the axes is movably supported with respect to the other one in longitudinal direction of the ski. BACKGROUND OF THE INVENTION Such a ski brake is known approximately from German OS No. 24 13 099, published Oct. 2, 1975. However, same has the disadvantage that the braking mandrels are positioned along the two sides of the ski in the retracted position of the braking bar, which can result in their getting caught on obstacles projecting from the ground and this can result in a fall of the skier. It is also known, for example from German OS No. 24 12 623, published Nov. 13, 1975, to design the braking mandrels retractable for the retracted position. However, either additional structural parts in the ski brake are needed for this, or the brake must have a special design. However, the special design is also associated with high manufacturing expenses due to required precision, because already small deviations from the aforedescribed technical information can lead to malfunctions. This is where the invention comes in and has as its objective the provision of a ski brake of the above-mentioned type such that its braking mandrels can be "pulled in" above the upper side of the ski in the retracted position also without additional structural parts and without requirements as to excessive precision. The set objective is attained according to the invention by the stationary axes of the braking bar being swingably supported with respect to the longitudinal axis of the ski. The inventive pivotal support of the normally stationary axes of the braking bar assures a wide range of various technical solutions for pulling in the braking mandrels, without requiring excessive precision in the manufacturing process. Due to the fact that the other pivot axis of the braking bar, as is actually known, is movably supported in the longitudinal direction of the ski, certain inexactnesses in the manufacture can be balanced only through the structure of the entire ski brake. DETAILED DESCRIPTION OF THE DRAWINGS Further advantages, details and inventively important characteristics of the invention are described more in detail hereinafter with reference to several exemplary embodiments and the drawings, in which: FIG. 1 illustrates a side view of a ski brake embodying the invention in the braking position; FIG. 2 is the top view of FIG. 1; FIG. 3 illustrates the ski brake of FIG. 2 in the retracted position; FIGS. 4 to 6 illustrate a different exemplary embodiment of an inventive ski brake, wherein FIG. 4 is a side view of the ski brake in the braking position, FIG. 5 is an associated top view of FIG. 4 and FIG. 6 illustrates the brake in the retracted position; and FIGS. 7 to 9 illustrate a further exemplary embodiment of an inventive ski brake, wherein FIG. 7 is a side view of the ski brake in braking position, FIG. 8 is an associated top view of FIG. 7 and FIG. 9 illustrates the ski brake in the retracted position. DETAILED DESCRIPTION The ski brake which is illustrated in FIGS. 1 to 3 has the following structure. A substantially rectangular base plate 2 is secured to the upper surface of the ski 1 by means of three countersunk screws 3, 3A and 3B. The countersunk screws 3 are arranged so that one of the three countersunk screws 3 extends through the base plate 2 and into the upper surface of the ski at the end thereof adjacent the tip of the ski and on the central longitudinal axis of the ski. The other end of the base plate 2 is secured by means of two countersunk screws 3A and 3B located on opposite lateral sides of said central longitudinal center line and these are arranged such they form with the aforedescribed countersunk screw 3 a substantially equilateral triangle. A bearing loop 4 is mounted on and secured to the rear half of the hose plate 2 in the region of the central longitudinal axis of the ski. The loop opens laterally outwardly and the band of material defining the loop extends parallel with respect to the longitudinal axis of the ski. The bearing loop 4 is constructed such that it permits the central portion a one-piece, substantially symmetricl braking bar 5, which will be described more in detail below, to move inside the loop in direction of the longitudinal axis of the ski. A wire section 5g of the one piece braking bar 5 is received in the loop 4 and is supported for movement along the longitudinal axis of the ski. The wire section 5g extends substantially perpendicular to the longitudinal axis of the ski. Approximately at half way between the central longitudinal axis of the ski and each side wall of the ski 1a, the substantially symmetrical braking bar 5, particularly at the opposite ends of the wire section has the first of several bent sections thereat 5a. The bent sections 5a each curve toward the tip of the ski and the front part of the braking bar 5 and through a generally 180° angle. The bent sections 5a lie in a plane parallel to the upper side 2a of the base plate 2. Thereafter, second bent sections 5b are provided following the first bent sections 5a; the second bent sections 5b are designed so that the wire extends toward the tip of the ski at approximately 90° from the end of the wire sections 5a and out of the plane parallel to the upper side 2a of the base plate at an angle θ (see FIG. 1) of approximately 45°. The wire sections 5b extend frontwardly so that they considerably project beyond the front edge of the base plate 2 in the retracted position (see FIG. 3) of the braking bar 5. Thereafter, third bent sections 5c are provided which are connected to the second wire sections 5b through a 180° angle bend and are positioned laterally outside of the second wire sections 5b. Furthermore, the plane of the second wire sections 5b forms with the plane of the third wire sections 5c an angle α of approximately 5°-10°. The wire sections 5e are located frontwardly of the wire sections 5b. The two second and third wire sections 5b and 5c also lie in planes perpendicular to the upper surface 2a of the base plate 2 and which extend substantially parallel to one another in the braking position (FIG. 2) and generally toward the wire segment 5g. Fourth bent sections 5d connected to the third bent sections 5c through an approximately right angle in direction toward the lateral edges of the ski (not identified in detail). The fourth bent sections 5d are designed so that they project bent sections 5e are connected to the outer ends of the wire beyond the lateral edges of the ski. Fifth sections 5d through an approximate 90° angle and extend in vertical planes which are parallel to the aforesaid planes containing the wire sections 5b and 5c. In addition, the wire sections 5c, 5d and 5e are coplanar in the plane extending at the angle α with the wire sections 5b. The fourth bent sections 5d define a pivot axle for the braking bar 5. An elongated bearing plate 6 is pivotally secured to the base plate 2 about a vertical axis 7. The pivot axes 7 are arranged on the ends of the bearing plates 6 facing the tips of the skis, such that the lateral edges thereof are flush with the side edges of the base plate 2 when the braking bar 5 is in the braking position. Each of the bearing plates 6 have at their ends which are remote from the axes 7 a 90° bent section 6a which extends upwardly away from the upper surface of the ski 1. The bent sections 6a also extend beyond the inner edge of the bearing plates 6 toward the center of the ski. The bearing plates 6 each have a channel 6B formed therein through which the wire sections 5d extend and are rotatable therein. The channels 6B define the pivot support for the wire sections 5c and 5e while the loop defines the pivot support for the wire sections 5a and 5b. It will be recognized that the wire section 5g slides in the loop between the forward and rearward extremities thereof. The braking part of the braking bar 5 is arranged below the bearing loop 4 in the braking position according to FIGS. 1 and 2 at the terminal end of the same, which terminal end is remote from the tip of the ski. If the braking bar 5 is now stepped down upon, it will pivot about the axes of the channels 6B in the bearing plates 6 and will pull, caused by the different lengths of the second and third wire sections 5b and 5c, the movably supported wire section 5g of the braking bar 5 in the bearing loop 4 in the direction toward the tip of the ski. When the fifth bent sections 5e are swung so far that they lie above the two upper lateral edges of the ski, the part of the braking bar 5 which forms the first bent sections 5a loads during the last portion of its sliding movement toward the tip of the ski the upwardly projecting bent sections 6a of the bearing plates 6 to cause these sections to be pivoted about their respective axes 7 inwardly toward the central longitudinal axis of the ski (see FIG. 3). This pivoting movement is transmitted through the fourth bent sections 5d onto the fifth bent sections 5e to cause the free ends thereof, which define the braking mandrels 8, to flex inwardly over the lateral edges of the ski. The braking bar 5 is torsionally stressed in the stepped-down or retracted position in its regions between the first and second bent sections 5a and 5b, and between the second and the third bent sections 5b and 5c. This torsional spring force is stored within the wire to cause an upward swinging of the braking bar 5 as soon as same is released from engagement with the ski boot or from the plate or the wire segments 5a of the like. At the start of the upward swing, the braking bar 5 become disengaged from the bent sections 6a of the bearing plates 6. During this disengagement, the braking mandrels 8 are swung outwardly beyond the ski edges. The braking bar 5 pivots further due to the described spring force into the braking position, as it is illustrated in FIGS. 1 and 2. The exemplary embodiment according to FIGS. 4 to 6 is constructed similarly to the one according to FIGS. 1 to 3. A base plate 2' is secured to the upper surface of the ski 1 by means of three countersunk screws 3, 3A and 3B which are arranged in a triangle arrangement as viewed from the top. The base plate 2' is slightly more narrow than is the ski 1. A bearing loop 4' is positioned centrally with respect to the longitudinal axis of the ski approximately in the center of the base plate 2'. A holding angle 10 is connected to the base plate 2' on each lateral side of the bearing loop 4', approximately in the center between the loop 4' and the edge of the base plate 2'. The holding angle is secured to the base plate 2' only at the rear end thereof and opens in the frontward direction toward the tip of the ski. In the half of the base plate 2' which is closest the tip of the ski, there is arranged on each side thereof one suitably bent bearing strap member 11, such that it is in alignment with the outer side edge of the base plate 2'. The bearing straps each have an opening therethrough larger in size than the diameter of the axle segments 5e' to thereby loosely rotatably support the axle segments and facilitate an angular movement of the axle segments to positions which are oriented at an acute angle to the longitudinal axis of the ski as shown in FIG. 6. A one-piece braking bar 5' has a wire section 5g' which extends through the bearing loop 4' substantially perpendicularly with respect to the longitudinal axis of the ski. The ends of the wire section 5g' extend beneath the holding part 10 and are bent thereat in a 180° angle toward the tip of the ski to thereby form the first bent section 5a'. The bent section 5a' lies in a plane parallel to the upper surface of the ski. The braking bar 5' is also bent in direction toward the tip of the ski such that its second bent sections 5b' do not only extend toward the central longitudinal axis of the ski, but also project upwardly from the plane of the upper side 2a' of the base plate at an angle φ of approximately 45° (FIG. 4). The second bent sections 5b' connected through a fairly large angle bend to third bent sections 5c' extending laterally in direction toward the lateral edges of the ski substantially perpendicularly with respect to the longitudinal axis of the ski in the braking position (FIGS. 4 and 5) of the braking bar 5'. Fourth bent sections 5d' are connected to the third bent sections 5c' extend in direction toward the central tail of the ski and the longitudinal axis of the ski. Furthermore, the plane of the second bent sections 5b' forms with the plane of the fourth bent sections 5d' an angle α of approximately 5° to 10°. Thereafter, fifth bent sections 5e' are connected to the fourth bent sections and extend substantially perpendicularly with respect to the longitudinal axis of the ski in the braking position of the braking bar 5'. The fifth bent sections 5e' extend laterally beyond the lateral edges of the ski. Sixth bent sections 5f' are connected to the fifth bent sections 5e' and extend alongside of the lateral edges of the ski. The ends of the sixth bent sections 5f' form at the same time the braking mandrels 8'. The operation of the ski brake from the braking position (FIGS. 4 and 5) into the retracted position (FIG. 6) is as follows. During a pressing down upon of the braking bar 5' in the area of its third bent section 5c', the braking bar pivots about the axis defined by the bearing strap 11. Due to the unequal lengths of the second bent sections 5b' and the fourth bent sections 5d', the wire section 5g' of the braking bar 5' extending through the bearing loop 4' and the first bent sections 5a' slide in direction toward the tip of the ski. Shortly before these parts of the braking bar 5' have reached their front endmost position in the bearing loop 4', the first bent sections 5a' engage the fifth bent sections 5e'. The parts of the fifth bent sections 5e', which parts lie within the two holding parts 10, are moved in direction toward the tip of the ski. This shifting causes a swinging of the fifth bent sections 5e' and is also transmitted onto the sixth bent sections 5f', which causes the sixth bent sections to swing to bring the braking mandrels 8' into a position overlapping the upper surface of the ski. The force, which is needed for swinging the braking bar 5' from the retracted position (FIG. 6) into the braking position (FIGS. 4 and 5), is derived from the torsion of the braking bar 5' in the area between the first bent sections 5a' and the second bent sections 5b' and in the area of the third bent sections 5c'. The first bent sections 5a' among others slide in direction toward the tail of the ski to become disengaged from the fifth bent sections 5e' to cause the braking mandrels 8' to be swung from their pulled-in position into a position outside of the lateral edges of the ski. During the further course of the pivoting movement of the braking bar 5', it assumes the position according to FIGS. 4 and 5. The third exemplary embodiment of the inventive ski brake is illustrated in FIGS. 7 to 9, and is substantially similar to the two exemplary embodiments which are illustrated in FIGS. 1 to 6. A base plate 2" is secured on a ski 1 by means of three countersunk screws 3, 3A and 3B similar to the two preceding exemplary embodiments. A bearing strap 21 is fixedly connected to the base plate 2" and is centrally disposed on the longitudinal axis of the ski and on the half of the base plate 2" remote from the tip of the ski. Bearing plates 6" are pivotally secured to the base plate 2" for movement about pivot axes 7". Each axis 7" is defined by a pin which is rigidly connected on each side of the central longitudinal center line of the ski and extends perpendicularly with respect to the plane of the base plate 2". The pivot axes 7" are spaced approximately equidistant from the countersunk screw 3. Each of the bearing plates 6" have a substantially tubular structural part which is rigidly connected to arms 20 which extend perpendicularly to the longitudinal axis of the ski, which arms are secured by the pin defining the pivot axis 7" to the base plate 2". The braking bar 5" has a wire section 5g" which extends perpendicular to the axis of the ski through the bearing 21. At each end of the wire section 5g", an approximate right angle first bent section 5a" is provided so that the section 5a" extends toward the tip of the ski. In the retracted position of the braking bar 5" (FIG. 9), the first bent sections 5a" project with approximately half of their length beyond the front edge of the base plate 2". Second bent sections 5b" are connected to the first bent sections 5a", which second bent sections 5b" extend toward the lateral edges of the ski. The second bent sections 5b" are designed approximately just as long as the wire section 5g" extending through the bearing. Third bent sections 5c" are connected to the second bent sections 5b" and extend from the plane of the sections 5g", 5a" and 5 b" in direction toward the ski 1 and form an angle α of approximately 15° to 20° with the aforesaid plane containing the first bent sections 5a". Fourth bent sections 5d" are connected to the third bent sections 5c" through a 90° angle and are received in the tubular parts of the bearing plates 6". The fourth bent sections 5d" are designed so long that the outer ends to which the braking mandrels 8" are connected will lie outside of the lateral edges of the ski. Upon the application of a downward force on the braking bar 5" in the area of the second bent sections 5b", the braking bar 5" pivots clockwise in the bearing 21. Due to the different length of the first and third bent sections 5a" and 5c" and the location of the various bearing axles of the braking bar 5", the wire is subjected to torsional stress. By torquing the braking bar 5", all parts of the braking bar 5" which lie within the bearing plates 6" are swung in direction toward the outer edges of the ski or the bearing plates 6" are swung in direction toward the tail of the ski. This swinging motion effects a pulling in of the braking mandrels 8" above the upper surface of the ski. The erecting force which is necessary for swinging the braking bar 5" from the retracted position (FIG. 9) into the braking position (FIGS. 7 and 8) is achieved by the torsion of the braking bar 5" in the area of the second bent sections 5b" and corresponds with the force with which the braking bar 5" resists the torsion when the angles α which are formed by the first bent sections 5a" and the third bent sections 5c" become smaller or approach 0. Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.	A ski brake made of spring wire and pivotally secured to a mounting plate which is in turn secured to the upper surface of a ski. The spring wire contains multiple bends therein with the spring wire being pivotally secured to the mounting plate about two axes which are spaced in the longitudinal direction of the ski. One of the pivot axes is centrally located on the mounting plate and movably supports the spring wire therein for movement toward the tip and tail of the ski. The other pivot axis of the ski brake is defined by a pair of laterally spaced axles which are located forwardly from the first-mentioned pivot axle and each are housed in bearing structures which will facilitate a pivoting of the axle about a vertical axis. This pivotal movement about the vertical axis can be by either making the axle housing the spring wire therein loose or by mounting the spring wire in a member which is in turn pivotally secured to the upper surface of the mounting plate.	8
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an enzyme-containing beverage and a method to produce the beverage, and more particularly to a beverage containing multiple enzymes obtained from fermented natural food to make a health beverage. 2. Description of Related Art Enzymes have been reported to have significant benefits to the human body, specifically enzymes assist all biochemical activities related to metabolism. Enzymes have the following characters to cure disease: 1. Refresh blood to change the constitution of the body: enzymes lyse foreign matter such as viruses or cholesterol to cause the blood to have weak basicity, to promote blood fluidity in blood vessels, and to prevent a chronic ailment and degeneracy of the body. 2. Have an antibiotic effect: enzymes enhance healing and recovery of hemoleukocytes to promote the immune system of the body. 3. Have a decomposing effect: some enzymes catalyse the digestive juice to decompose food in the digestive system to make nutrients in food easily absorbed by the intestines. 4. Activate cells: enzymes promote cells to metabolize to generate energy and generate new cells for healing. Enzymes can even activate degenerated reproductive cells. 5. Have anti-tumor and anti-cancer effect: in cooperation with suitable medicine and nutritious substances, enzymes catalyze the medicine or nutritious substances and reduce side effects of the medicine. 6. Have a sobering effect with regard to alcohol to prevent headaches associated with a hangover. 7. Supplement nutrition and energy. Having many advantages as mentioned above, enzyme products are popular as a health food. However, enzyme products are made in the form of solid powders or tablets and only contain a few kinds of enzymes. Therefore, conventional enzyme products cannot supply consumers with various enzymes to satisfy different requirements for enzymes in the body so the efficiency of conventional enzyme products is not significant. SUMMARY OF THE INVENTION To overcome the shortcomings of conventional enzyme products, the present invention provides an enzyme-containing beverage to mitigate and obviate the aforementioned problems. A first objective of the invention is to provide various enzymes obtained from fermented natural food in a beverage form, where the beverage is composed of multiple fermented fluids in a proper proportion and enhances immunity and activation of the body. A second objective of the invention is to provide a method for producing the beverage containing various enzymes described in the first objective. Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: FIG. 1 is a functional block diagram of a method for producing an enzyme-containing beverage obtained from natural food in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1 , a method for producing a beverage containing enzymes obtained from natural food in accordance with the present invention comprises the acts of: providing extract from a pine tree; mixing the extract from a pine tree with sugar and placing the mixture to produce fermented pine extract; providing a composite fermentation fluid obtained from the fermentation of vegetables and fruits; and mixing the composite fermentation fluid and the fermented pine extract to form the enzyme-containing beverage. Parts of the pine tree are squeezed to obtain pine extract, and the extract from pine tree is stored in a container with sugar or honey. The container of pine extract is sealed and vented and stored under proper conditions at room temperature for at least one month until the pine extract ferments. After fermenting, the fermented pine extract contains plenty of enzymes. Pine extract is selectively obtained from part of a pine tree such as stems, needles, pine cones, etc. because each part of the pine has its application in folk medication. For example, needles of Japanese red pine ( pinus densiflora S. et Z,;) contains plenty of chlorophyll, vitamin A and C, various of vitamin groups, protein, carbohydrate, oil of turpentine, iron, phosphorous, calcium, etc. so that pine extract of needles can refresh the body, enhance physical endurance, activate cells, strengthen the heart and smooth the flow of blood in blood vessels. The composite fermentation fluid obtained from fermented vegetables and fruits is made by the following acts: providing vegetables and fruits; mixing each kind of the vegetables and fruits with sugar and vinegar and placing the mixture for at least four months to produce a fermentation fluid; separating the fermentation fluid from the fermentation of each kind of vegetable or fruit; and mixing the fermentation fluid of each kind of vegetable or fruit to form a composite fermentation fluid. Multiple kinds of fresh vegetables and fruits are selected to provide the raw material for producing fermentation fluids and are cleaned. Large vegetables and fruits are chopped into small pieces. Each kind of vegetable and fruit is stored individually in a container and mixed with vinegar and sugar (or honey). The containers are hermetically sealed and vented and stored under proper conditions at room temperature for at least four months to ferment the vegetables and fruits and produce individual fermentation fluids. The individual fermentation fluids are separated from the residue and mixed in equal parts with each other to form a composite fermentation fluid. When the vegetables and fruits ferment completely, the fermentation fluids contain plenty of enzymes. The selected vegetables and fruits comprise lemons, grapes, apples, peaches, night-blooming cereus fruit ( Hylocereus undatus ), plums, mountain or Chinese yams ( Dioscoreaspp .), papayas, mulberries, kumquats, red jujubes, guavas, cherries, beets and tomatoes. The vinegar is made of natural food and is selected from a group of fruit vinegar, glutinous-rice vinegar and rice vinegar. The sugar is selected from sucrose, fructose, glucose and others. The composite fermentation fluid and the fermented pine extract are mixed to form an enzyme-containing beverage containing various enzymes. The composite fermentation fluid makes up 60˜90% (w/w) of the enzyme-containing beverage, and the fermented pine extract makes up 10˜40% (w/w) of the enzyme-containing beverage. The enzyme-containing beverage may be further mixed with fermented paper-mulberry extract to enhance the variety and efficiency of the enzyme beverage. Therefore, the method for producing the enzyme-containing beverage may further comprise acts of: providing extract from a paper-mulberry tree ( Broussoneta papyrifera (L.)); mixing the extract from a paper-mulberry tree with sugar and placing the mixture to produce the fermented paper-mulberry extract; and mixing the fermented paper-mulberry extract with the mixture of the composite fermentation fluid and the fermented pine extract. Parts of the paper-mulberry tree are squeezed to obtain paper-mulberry extract. Then, the paper-mulberry extract is hermetically stored in a vented container and mixed with sugar or honey under proper conditions at room temperature for at least one month until the paper-mulberry extract ferments. After fermenting, the fermented paper-mulberry extract contains plenty of enzymes. The paper-mulberry extract is selectively obtained from any parts of a paper-mulberry tree because each part of the paper-mulberry tree has its application. For example, leaves of the paper-mulberry tree are uretic. Fruits of paper-mulberry fruit were reported to be capable of treating liver ailments and impotence. The fermented paper-mulberry extract is mixed with the mixture of the composite fermentation fluid and the fermented pine extract in a concentration of 3%˜15% (w/w) of the mixture of the composite fermentation fluid and the fermented pine extract. Because condensation and numbers of each enzyme increase after fermenting, the fermented vegetable and fruit fluids, fermented pine extract and fermented paper-mulberry extract contain plenty of enzymes. After mixing the fermented fluids and extracts together, various enzymes interact and produce auxiliary effects. As described, the enzyme beverage contains multiple kinds of enzymes and enhances immunity and activation of the body. Although the invention has been explained in relation to its preferred embodiment, many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.	An enzyme-containing beverage has various types of enzymes and basically has fermentation fluid obtained form fermented vegetables and fruits and fermented pine extract, and optionally further having fermented extract from a paper-mulberry tree. A method produces the enzyme beverage for fermenting the raw materials (vegetables, fruits, pine extract, and paper-mulberry extract).	0
This is a division, of application Ser. No. 06/081,607, filed Oct. 3, 1979, now U.S. Pat. No. 4,309,370. FIELD OF THE INVENTION The present invention relates to plastic molding apparatus and the formation of plastic electrical connector bodies along a molded continuous strip. Further, the invention relates to apparatus for over-molding plastic products together in a continuous strip, including an indexing mechanism, electrically programmed, to remove molded product upon the completion of the molding cycle, and to position the molded product for over-molding. BACKGROUND OF THE INVENTION An electrical connector requires an assembly of one or more metal contacts, for electrical termination to an electrical conductor, and a plastic connector body or housing, which encircles and insulates the metal contact and a terminated portion of the electrical conductor. The electrical contacts are produced along a continuous strip which may be reeled on a spool and let out as needed for automated assembly of the contacts into the connector bodies. The connector bodies are fabricated by plastic molding apparatus. Such apparatus is not suited for producing plastic connector bodies on continuous strip. Accordingly, the bodies are molded individually or in groups along a molded strip segment of finite length. Many strip segments must be joined together to provide a continuous strip of serially arranged connector bodies suitable for automated assembly with the contacts. Connecting strip segments together into a continuous strip was heretofore time consuming. According to one process, an operator fed individual strip segments to a heat staking machine which applied heat and pressure to remelt and join together consecutive strip segments. An improved process involves joining strip segments as they are being produced in a molding apparatus. Each time a molding apparatus is cycled to produce a strip segment, a previously made strip segment is positioned at the molding apparatus and is over-molded with the strip segment being produced. SUMMARY OF THE INVENTION The present invention relates to a stepping motor and matched electronic control unit for operating a molding cycle and a drive motor end which automatically withdraws molded product from a molding apparatus and positions the product for over-molding, so that repeated cycling of the molding apparatus occurs without the need for operator attentiveness to produce a continuous strip of molded products. A typical molding cycle of the molding apparatus comprises, closing together a pair of molding dies having die cavities cooperating with one another, injecting plastics material in a molten state into the die cavities, forming the plastics material and curing the plastics material to a solid state to form a molded product, opening the dies by separation one from the other, and removing the product from the dies. The product consists of a group of connector bodies spaced along a molded strip segment. The molding cycle is repeated to provide additional connector bodies along another strip segment which is over-molded onto an end of the strip segment made during the previous molding cycle. A reeling device, driven by a reversible, precision stepping motor, removes molded product from the dies and positions each strip segment in preparation for over-molding in a repeated molding cycle. Each strip segment is molded with an interlocking structure which, when over-molded with a subsequently formed strip segment, provides a continuous strip having a uniformity which will not buckle or bind when reeled on a spool or handled in a feeding mechanism. The molding cycle and the reeling device are automatically controlled for repeated operation without operator attention. OBJECTS An object of the present invention is to provide apparatus for molding a plurality of plastic connector bodies serially along an integral strip segment, formed with interlocking structure to which a subsequently molded strip segment is joined during formation thereof by repetition of the molding cycle of the apparatus. Another object is to provide a molding apparatus with a reeling device driven by a reversible precision motor, to remove molded product from the apparatus, to position the product for over-molding, and to slacken the molded strip product to allow for movement thereof during a repeated molding cycle. Another object is to provide plastic molding apparatus having an automatically controlled repeatable molding cycle, and further having automatically controlled apparatus, for withdrawing molded strip product, and for positioning the product for over-molding during a repeated molding cycle. Another object is to provide a precision reeling apparatus for removing plastic molded strip product from a mold and for precisely locating the strip product for over-molding and joinder to additional molded strip product formed during a repeated molding cycle. Another object is to provide apparatus for molding a plastic strip product and, by repeating the molding cycle, forming additional strip product while joining the same to a previously formed strip product, to result in a reelable continuous length of strip products. Another object is to provide apparatus for molding a plurality of strip products by repeated molding operations, and for joining the strip products by over-molding, one to the end of another, during one molding operation, with the apparatus including a reversible precision reeling device which removes strip product from the molding apparatus, positions the strip product for over-molding, and provides slack in the joined lengths of strip products to allow for displacement thereof during a repeated molding cycle. Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. DRAWINGS FIG. 1 is a fragmentary elevation in section of a preferred embodiment of a molding apparatus according to the invention, illustrating closed molding dies and a series of mold products on continuous strip in conjunction with a reeling device which provides slack in the continuous strip to allow movement thereof in response to closure of the mold dies during a molding cycle. FIG. 2 is a fragmentary enlarged elevation in section of a portion of the molding apparatus, illustrating a strip segment over-molded on to a previously made strip segment, and further illustrating, a pilot pin, for aligning a previously made segment, and electrical switch controls, which prevents closure of the molding dies if the previously made segment is misaligned. FIG. 3 is a fragmentary enlarged elevation in partial section illustrating the mold dies opened, and the molded product removed and positioned by the reeling device for a repeated molding cycle. FIG. 4 is a fragmentary enlarged elevation of the reeling device and a reversible stepping motor drive which drives the reeling device to provide slack in the strip to allow movement thereof in response to closure of the mold dies during a subsequent molding cycle. FIG. 5 is a fragmentary enlarged elevation illustrating the reversible stepping motor and a pair of reeling devices for two mold cavities. FIG. 6 is a fragmentary enlarged elevation illustrating a pair of ejector blocks for the mold cavities of the molding apparatus, with one of the blocks illustrated with a cover plate and a die button for guiding the pilot pin. FIG. 7 is an enlarged fragmentary elevation of an end of a molded strip segment, illustrating a channel and countersink recesses for receiving over-molding by another strip segment. FIG. 7A is a fragmentary perspective of the strip segment of FIG. 7. DETAILED DESCRIPTION With more particular reference to the drawings there is illustrated in FIG. 1 generally at 1 molding apparatus according to the present invention comprising a mold half A provided with a molding die 2, and a mold half B provided with a die 4. Mold half A is provided with injectors 6 communicating with a die cavity 8 in the die 2. Die cavities 10 in the die 4 cooperate with the die cavity 8 when the dies are in closed cooperation. It is understood that additional cooperating die cavities 8 and 10 may be provided in the dies 2 and 4, although not specifically shown in the Figure. FIG. 5 shows the plastic product 11 formed by the die cavities 8 and 10 upon completion of a molding cycle. A plurality of connector bodies 12, formed in the die cavities 10, are serially located along an integral strip segment 14, formed in the die cavity 8. Pilot holes 16 are provided through the strip 14 and are utilized for conveying the strip segment, in a manner to be described. The strip segment 14 is formed in a vertically elongated orientation in the mold as shown in FIG. 1. The lower most terminal end 18 of the strip segment 14 is formed with an axially elongated, side opening channel 20. On an opposite side, the end portion 18 is provided with a pair of tapered countersink recesses 22 which open into the channel 20. FIG. 1 illustrates a pair of core pins 24 in the B half of the mold. The pins 24 are actuated, according to well known principles in the plastics molding art, to enter the die cavity 8 at the appropriate time, so that plastics material forms around the pins to produce the recesses 22 in the molded product. As shown in FIGS. 1 and 2, the mold half B is provided with an ejector block 26 driven by a reciprocating ejector pin 28. With the die halves A and B closed, the ejector block 26 is recessed in a side-opening cavity 30 of the mold half B, with the ejector pin 28 reciprocated toward the left. Mold half A is provided with an elongated pilot pin 32 reciprocating in a bore 36. An end of the pin 38 projects into a corresponding bore 40 of the ejector block 26. The other enlarged end 42 of the pin seats against a positioning block 44 to limit forward movement of the nose portion 38 into the bore 40. The pin is biased forwardly by a plunger 46 of a spring biasing plunger device 48 fixedly mounted in the mold half A. A notch 50 in the side of the pilot pin 32 receives therein a lever 52 of a lever actuated electrical switch 54. Electrical leads 56 of the switch 54 extend along a passageway 58 in the mold half A, and are routed to an electric control unit of the type for driving a stepping motor, supplied by Superior Electric Company, Binghamington, N.Y., model number M063-FD06. If the pilot pin 32 is prevented from entering the bore 40 during closure of the mold halves, the pin will be depressed against the spring loaded plunger 46 causing the lever 52 to pivot counterclockwise as shown in FIG. 2. An electrical signal thereby is produced by the switch 54 and supplied to the control unit to halt closure of the die halves. When the mold product has sufficiently solidified in the die cavities 8 and 10, the control unit is activated to open mold half B away from the fixed mold half A, as shown in FIG. 3. According to a well known practice in the plastic molding art, the control unit actuates a suitable motor drive of a pressure plate 60, which is reciprocated to drive the ejector pin 28 as well as additional ejector pins (not shown) to impel the solidified product outwardly of the die cavities 10 and into the space between the separated mold halves A and B. The molded product 11 is held away from the die 4 by the ejector block 26 as shown in FIG. 3. The control unit then activates a suitable drive motor to activate and rotate a drive wheel 62 counterclockwise, with teeth 64 along the circumference of the wheel engaging in the pilot holes 16 of the product 11, vertically removing the same from between the opened dies 2 and 4, and traversing the product 11 along channel 65 in the face of the mold half B. A spring finger 67 retains the product 11 against the wheel 62. As shown in FIG. 6 the block 26 is provided with a pair of vertical channels 66 separated by a rib 68. As the product is vertically removed, the connector bodies 12 will traverse along the channels 66 while the strip segment is supported along the rib 68. In FIG. 6 a cover plate 70 overlies the passageways 66 and the rib 68, with a space between itself and the rib 68 to accommodate vertical passage of the product 11. A die button 72 having a central aperture 74 is provided in the cover plate to provide a guide for the pilot pin 32. As shown in FIG. 3, taken in conjunction with FIG. 6, the face of mold half B is provided with additional recesses 10A located between the ejector block 26 and the die 4. The drive wheel 62 locates an end of the molded product 11, such that the lower most pairs of connector bodies 12 are located opposite the recesses 10A. During a repeated molding cycle, the mold halves A and B will close together, with the ejector block 26 becoming recessed within the face of the mold half B, thereby inserting the lower most connector bodies 12 into the recesses 10A. The pilot pin 32 will enter the die button 72, and will pass through a pilot hole 16 of the molded product 11, and then into the bore 40 of the ejector block 26. If the product 11 is misaligned, the pilot pin will impinge against the carrier strip segment 14 which covers the bore 40 and will be displaced, overcoming the biasing action of the plunger 46, as the die halves A and B close together. The switch 54 will then be actuated, due to the position of the pilot pin, to prevent closure of the mold halves. Operator attention will then be required to restart the molding cycle after making adjustments. To achieve repeated molding cycles without operator attention, the drive wheel 62 must be driven by a precision stepping motor, as shown in FIG. 5 at 76, of the type supplied by Superior Electric Company and matched to the heretofore identified control unit. The output shaft 78 is attached by a coupler 80 to the shaft 82 on which the drive wheel 62 is secured. A pair of drive wheels 62 are shown coupled together; one for removing each of a pair of strip segments 11 produced simultaneously by a single molding cycle. A pair of bearing blocks 83 rotatably mounting each shaft 82 are mounted to a mounting flange 84, which is in turn mounted to the mold half B. The motor 76 is supported by a mounting flange 86 which is in turn secured to the mounting flange 84. As shown in FIGS. 3 and 4, a plunger actuated, electrical switch 88 is mounted on the mold half A with the plunger 90 thereof projecting toward a strike plate 92 mounted on the mold half B. As the mold halves A and B close together, the plunger 90 will impinge against the strike plate 92, depressing the plunger and activating the switch 88 which signals the control unit to rotate the drive wheel 62 clockwise as shown in FIG. 4. The continuous strip of molded products 11 will thereby slacken to allow for movement thereof in response to movement of the mold halves as they close together during a molding cycle. The stepping motor 76 is capable of a precise amount of clockwise rotation to produce a corresponding desired slack. Although a preferred embodiment of the present invention is disclosed and described in detail, other embodiments and modifications thereof which would be apparent to one having ordinary skill in the art are intended to be covered by the spirit and scope of the appended claims.	Plastic molding apparatus is disclosed for forming a series of molded connector bodies along a molded strip segment. By repeating the molding cycle, an additional strip segment is simultaneously molded and joined to a previously made strip segment, so that repeated cycling of the molding machine provides a molded continuous strip interconnecting a series of molded bodies.	1
This is a division of application Ser. No. 734,319 filed May 14, 1985 now Pat. No. 4,719,498. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method for producing the same, more particularly to a semiconductor device in which both optical semiconductor elements and ordinary electronic semiconductor elements are substantially flatly formed on a single substrate. 2. Description of the Related Art Recent advances in the technologies of crystal growth and device production have make it possible to combine optical and electronic devices into a single chip. Such an optoelectronic integrated circuit (OEIC) is not only smaller and easier to use in various systems but also speedier, more reliable, and less noisy than hybridized discrete devices. A particularly attractive and important OEIC is one wherein an optical semiconductor element, for example, a laser diode (LD) or photo diode (PD), is monolithically integrated with a field effect transistor (FET) driver. In fabricating a laser/FET unit or PD/FET unit, there is a problem in how to match the laser structure to the FET structure, as each component has a very different layer structure. A laser has a higher structure than FET's. As conventional photolithographic technology requires a wafer with an even surface, the laser must therefore be formed in an etched groove. Assuming the substrate is one of (100) oriented semiinsulating GaAs substrate, when the substrate is chemically etched, a (011) face is exposed as a side wall, the (011) face forms a 55° angle with respect to the (100) top surface so that a groove having a sharp step is formed. This sharp step itself, however, makes application of the photolithographic technology difficult. Thus, high integration of the laser/FET unit becomes difficult. Further, the sharp 55° angle step often results in breakage of wiring and thus a reduced production yield. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above disadvantages of the prior art. Another object of the present invention is to provide a method for producing a semiconductor device wherein both optical semiconductor elements such as, a laser diode, and ordinary electronic semiconductor elements, such as an FET, are formed nearly flatly on a single substrate. Another object of the present invention is to provide a semiconductor device wherein optical semiconductor element/ordinary semiconductor unit is formed on single substrate with high integration. According to the present invention, there is provided method for producing a semiconductor device including the steps of: forming a lower substrate surface i.e. a recess area in a substrate with a gentle slope from the substrate surface; forming on the lower substrate surface or recess area a single crystalline layer substantially level with the substrate surface; forming an optical semiconductor element and an electronic semiconductor element using the single crystalline layer and the substrate surface, respectively; and forming a wiring layer connecting the optical semiconductor element and the electronic semiconductor element on the gentle slope. According to the present invention, there is further provided a semiconductor device including: a substrate having a lower substrate surface formed in the substrate with a first gentle slope from the substrate surface; a single crystalline layer formed on the substrate surface nearly level with the substrate surface and having a second gentle slope facing the first gentle slope; an optical semiconductor element is constructed using the single crystalline layer. An electronic semiconductor element is constructed using the substrate surface. A wiring layer connects electrodes of the optical semiconductor element and the electronic semiconductor element through the first and the second gentle slopes. According to the present invention, there is still further provided a method for producing a semiconductor device including the steps of: forming a substrate; forming a low substrate surface in the substrate surface with a first gentle slope from the substrate surface; forming on the low substrate surface a single crystalline layer nearly level with the substrate surface; forming in the single crystalline layer a second gentle slope facing the first gentle slope; forming an optical semiconductor element using the single crystalline layer; forming an electronic semiconductor element using the substrate surface; and forming a wiring layer connecting the electrodes of the optical semiconductor element and the semiconductor element through the first and the second gentle slopes. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 1K are cross-sectional views for explaining an embodiment of a method for producing a semiconductor device according to the present invention. FIGS. 2 and 3 are partially enlarged cross-sectional views of FIG. 1K; FIG. 4 is a perspective view of FIG. 1K; FIG. 5 is a schematic circuit diagram of the devices of FIG. 4; FIGS. 6A and 6B are cross-sectional views for explaining an embodiment of a semiconductor device according to the present invention; FIG. 7 is a schematic circuit diagram of the device of FIG. 6; FIG. 8 is a cross-sectional view of another embodiment of a device according to the present invention; FIG. 9 is a perspective view relating to FIG. 8; FIG. 10 is a schematic circuit diagram of the device of FIG. 9; FIGS. 11A and 11B are cross-sectional views for explaining an embodiment of a method for forming a gentle slope in a substrate; FIGS. 12A and 12B are cross-sectional views for explaining another embodiment of a method for forming a gentle slope in a substrate; FIGS. 13A and 13B are cross-section views for explaining still another embodiment of a method for forming a gentle slope in a substrate. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments will now be described with reference to the drawings. FIGS. 1A to 1K are cross-sectional views for explaining an embodiment of a method for producing a semiconductor device according to the present invention. After providing a GaAs substrate 1 as shown in FIG. 1A, a photo resist 2 for example, AZ4620 (produced by Hoechst), having a thickness of 5 to 15 μm is formed over the surface of the GaAs substrate 1 and patterned in a stripe form, as shown in FIG. 1B. The width W of the stripes of the resist layer may be 50 to 200 μm, preferably 100 μm. And the thickness d may be 7˜8 μm. Next, as shown in FIG. 1C heat treatment for baking is carried out for 10 minutes at a temperature of 200° C. to change the edges of the resist layer 2 to gentle slopes and increase the thickness d' of the resist layer 2 to about 8 to 10 μm. In this heat treatment, the temperature is 200° C. which is higher than the usual post baking temperature 120° C. And the width W will not be changed so that the slope α of the edge of the mask 2 is approximately 5°[15°. The thickness d' of the resist mask should be larger than the total thickness of the semiconductor laser layer which will be formed in a groove later. There are some rules which decide the slope of the heated mask. That is, one relationship between W and d corresponds to one slope of the edge. As shown in FIG. 1D, a resist layer 3 is formed over the obtained structure and then patterned. The patterned resist layer 3 has a thickness of 5 to 15 μm. Since the resist layer 2 had been heat-treated, it is not removed in the patterning process of the resist layer 3. Thus, the gentle slopes of the resist layer 2 facing the center in of FIG. 1D are exposed, which the other slopes are protected by the resist layer 3. A slight heat-treatment is carried out to dry the patterned resist layer 3. As shown in FIG. 1E, an ion beam etching, for example, argon ion (Ar + ) beam etching, is used to etch a mesa while rotating the GaAs substrate 1: In this ion beam etching process, the ion beam irradiates the GaAs substrate 1 at an angle of about 70°. When the mesa height h is about 10 μm, the ion beam etching process is ended. Thus, a groove 4 having a slope 12 angle α of about 5° to 15° is formed in the GaAs substrate 1. The ion beam etching conditions are an acceleration voltage of 500 and an ion current density of 0.57 mA/cm 2 That is, the ion beam etching process etches all of the surface of the substrate equally, irrespectively of the various materials thereof. As a result, the surface shape of the mask 2,3 is shifted to the surface of the etched substrate 1. As shown in FIG. 1F, the resist layers 2 and 3 are then removed, resulting in a GaAs substrate 1 having a mesa type recess or groove 4 with a gentle slope 12. As shown in FIG. 1G, a semiconductor laser layer 5 consisting of an n + type GaAs layer, n type Al 0 .3 Ga 0 .7 As layer, etc. is grown over the entire the GaAs substrate 1 by molecular-beam epitaxy (MBE). The structure of the layers corresponds to that of the optical semiconductor element, i.e. an LD or a PD. As shown in FIG. 1H, the semiconductor laser layer 5 is then patterned using two above-mentioned gentle-slope forming steps, which is shown as the mask 2',3' in FIG. 1G. As shown in FIG. 1I an SiO 2 layer 7 is formed over the obtained structure and then patterned so that the SiO 2 layer covers the layer 5 formed in the etched groove. Then an FET epitaxial layer 8 is grown on the substrate while forming a polycrystalline (Al)GaAs layer 9 on the SiO 2 layer 7. The structure of the FET epitaxial layer 8 corresponds that of an FET the thickness of which is not as great as the semiconductor laser layer 5. As shown in FIG. 1J, the polycrystalline (Al)GaAs layer 9 is removed by a chemical etching process using a resist layer 10 as a mask. After that, the SiO 2 layer 7 is also etched and the resist layer 10 is removed. Then, various LD and FET electrodes and a wiring layer 11a, 11b are formed on the gentle slope 12 as shown in FIG. 1K. The reason for making the gentle slope 12 is mainly two points which are necessary for making the OEIC. The first, in order to deposit the wiring layer on the slope between the LD and FET, the slope should be gentle; because it is quite difficult to deposite a sufficiently thick wiring layer on a sharp slope as used conventionally. Secondly, in the patterning process of the wiring layer 11a, 11b formed on the entire surface of the substrate, a photo resist layer should be coated on the wiring layer. The thickness of the coating resist layer should be large enough to cover properly even on a sharp slope. This means the thickness of the resist coated on the upper surface where the FET's wiring is patterned becomes thick. This causes it to be impossible to make a fine pattern for the FET IC because of the thick resist. On the other hand, in the present invention, since the slope is gentle, the coating resist can be thin where it is possible to make a fine pattern. A detailed explanation relating to FIG. 1K will be given below. FIG. 2 is a partially enlarged cross-sectional view of FIG. 1K, illustrating an embodiment of a structure according to the present invention. In FIG. 2, reference numeral 1 represents the GaAs substrate, 14 the semiconductor laser layer structure which is multilayer, 15 a recess, 15a, 15b, 15c a gentle slope, 16 an n side contact layer of an n + type GaAs, 17 an n side clad layer of n type Al 0 .3 Ga 0 .7 As, 18 an active layer of either n type or p-type GaAs, 19 a p side clad layer of p type Al 0 .3 Ga 0 .7 As, 20 a p side contact layer of p + type GaAs, 21 an FET layer, 22 an undoped GaAs layer, 23 an n GaAs FET active layer, 25 a p side contact electrode of AuZn, 26 a source electrode of AuGe/Ni, 27 a drain electrode of AuGe/Ni, 28 a gate electrode of Al, 30 an insulating layer of SiO 2 , and 31a a wiring layer of Au/Cr. Although, in FIG. 1K, there is a step on the left hand side gentle slope, it is possible not to form such a step slope shown at the gentle slope 15b in FIG. 2. A method for producing the structure of FIG. 2 in which the p side contact electrode 25 is connected to the drain electrode 27 through the wiring layer formed on the gentle slopes 15a and 15b, will be explained below in detail. After forming a recess 15 having the gentle slopes 15a as explained above, the n side contact layer 16, the n side clad layer 17, the active layer 18, the p side clad layer 19 and the p side contact layer 20 are successively formed. The multilayer 14 consisting of the n side contact layer 16 to the p side contact layer 20 is patterned by the above-mentioned gentle-slope forming process. Then, the FET layer 21 consisting of the undoped GaAs layer 22 and n GaAs active layer 23 is formed by MBE, as explained above in FIG. 1I, 1J. The p side contact electrode 25 for the LD is then formed on the p side contact layer 20 by a lift-off process. After that, the n side contact electrode 33 is formed on the n side contact by a lift-off process and an alloying. The source electrode 26 and the drain electrode 27 for the FET are also formed on the FET layer 21. The insulating layer 30 is formed over the obtained structure by a sputtering process and is patterned by photolithography. A wiring layer 31a is formed on the gentle slope 15a, 15b via the insulating layer 30 by a lift-off process. Thus, the structure of FIG. 2 can be formed on a single GaAs substrate. FIG. 3 is another partial enlarged cross-sectional view of FIG. 1K. In FIG. 3, the same reference numerals as in FIG. 2 represent the same portions. As seen from the figure, the source electrode 26 is connected to the n side contact electrode 33 through the wiring 31b formed on the gentle slope 15d via the insulator layer 30. FIG. 4 is a perspective view relating to FIG. 1K, FIG. 1K being a cross-sectional view taken along the AA line. FIG. 5 is a circuit diagram of the device of FIG. 4. As easily understood from the accordance between the FIG. 4 and FIG. 5, the wiring 31a on the gentle layer 15a, 15b connects between the LD and the FET Q 2 , and the wiring 31b on the gentle layer 15d connects between the LD and the FET Q 1 . In this embodiment, the LD and Q 2 can be connected by the wiring 31a formed in OEIC so that the characteristic of the OEIC is improved. FIG. 6A is a cross-sectional view for explaining another embodiment of a semiconductor device according to the present invention. In FIG. 6A, the LD and FET are also formed on a GaAs substrate 1. The drain electrode 27 is connected to the p side contact electrode 25 via the wiring 31c formed on the planar surface. The process of this embodiment is almost same as the process shown in FIG. 1A-1H. That is, as shown in FIG. 6B, after forming the semiconductor laser layer 5, the combination mask 2" and 3" is formed so that the edge of the mask 2",3" corresponds to the slope of the layer 5 (shown 5a). After that the planar surface 32 can be formed on the gentle slope 15a by performing the ion beam etching process as explained above. The same reference numerals as in FIG. 2 and 3 represent the same portions. FIG. 7 is a schematic circuit diagram of the device of FIG. 6. FIG. 8 is a cross-sectional view of another embodiment of a device according to the present invention. In FIG. 8, a pin photo-diode (PIN PD) and an FET are formed on a single semi-insulating GaAs substrate 1. In FIG. 8, reference numeral 40 is an n + type GaAs layer, 41 an n - type GaAs layer, 42 a high resistivity Al 0 .3 Ga 0 .7 As layer, 43 a Zn diffused region, 45 an Si 3 N 4 layer 46 an undoped GaAs layer, 47 an n type GaAs layer, 48 an Al electrode, 50 a wiring layer of Au/Ti, 51 an Au/AuGe electrode, and 52 an Au/Zn/Au electrode. As shown in FIG. 8, the Al electrode 48 is interconnected to the Au/Zn/Au electrode through an Au/Ti wiring layer 50 continuously laid on the gentle slopes 15a and 15b. FIG. 9 is a perspective view of the device of FIG. 8 which is a cross sectional view of B--B. FIG. 10 is a circuit diagram of the device of FIG. 9. Another method for forming a recess having a gentle slope in a semi-insulating GaAs substrate will now be explained. FIGS. 11A and 11B are cross-sectional views of an embodiment explaining one of the methods. As shown in FIG. 11A, a resist layer 61 having a thickness of, for example, 6 μm is formed. The resist layer 61 is then exposed through a mask of a photosensitive glass 62 having a hole 64 with a taper wall and a glass fiber 63. The resist layer just under the glass fiber 63 is most exposed, and as the distance is larger from the position on the resist layer just under the glass fiber, the amount of exposure is gradually reduced. Thus, as shown in FIG. 11B, the resist layer has a pattern 66 having a gentle slope 65. After that, using ion etching or reactive ion etching, the entire surface of the obtained structure is etched. Thus, a recess having the same pattern 66 can be formed in the semi-insulating GaAs substrate 1. FIGS. 12A and 12B are cross-sectional views for explaining another embodiment of a method for forming a gentle slope in a substrate as shown in FIG. 12A, a polyimide layer 68 having a thickness of, for example, 6 μm is formed on a semi-insulating GaAs substrate 1. The polyimide layer is irradiated with a laser so that a portion of the polyimide 68 in which a recess having a gentle slope is formed is irradiated less compared to the surrounding portion. The center of the recess forming portion may be not irradiated at all. After that, the recess forming process for the semi-insulating GaAs substrate is carried out as explained with FIG. 11B. FIGS. 13A and 13B are cross-sectional views of another embodiment explaining a method for forming a gentle slope in a substrate. As shown in FIG. 13A, a first polyimide resin layer 72 1 having a thickness of, for example, 6000Å is formed on a semi-insulating GaAs substrate 1. Then, the first polyimide resin layer 72 1 is heat-treated at a first temperature T 1 of, for example, 200° C. A second polyimide resin layer 72 2 is formed on the first polyimide resin layer 72 1 and is heat-treated at a second temperature T 2 of, for example, 180° C, lower than the first temperature T 2 . The process is repeated until the nth polyimide layer is formed on the (n-1)th polyimide layer and is heat-treated at a temperature T n lower than temperature T n-1 . Thus, a polyimide resin multi-layer 72 is formed on the semi-insulating GaAs substrate. When a polyimide resin is heat-treated at a higher temperature, the etching rate is decreased. Then, as shown in FIG. 13B the polyimide resin multilayer 72 is etched by an etchant, using a resist layer 73 having an opening 74 as a mask so that an recess 75 having a gentle slope 76 is formed in the polyimide multilayer 72. Then, the recess forming process as explained in FIG. 11B. is carried out for the semi-insulating GaAs substrate. Furthermore, another embodiment will be explained by using the FIG. 13A, 13B. In this embodiment, the multi-layer 72 1 , 72 2 . . . 72 n comprises Al x Ga 1-x As layers in which the x is gradually increased from 72 1 to 72 n . Then, the wet etching process using an etchant containing HF is performed so that since the AlGaAs is etched faster than the GaAs or AlGaAs with a small quantity of Al, the etched pattern becomes as shown in FIG. 13B having a gentle slope 76. After that, there is an alternative way. The first way is that the ion beam etching is simply performed in the same manner as the previous explained process. The second way is that since the multi-layer 72 comprises AlGaAs compound semiconductor, the FET structure is formed on or in the multi-layer 72.	A semiconductor device including a substrate having a low substrate surface formed in the substrate with a first gentle slope from the substrate surface; a single crystalline layer formed on the low substrate surface nearly level with the substrate surface and having a gentle slope facing the first gentle slope; an optical semiconductor element is constructed using the single crystalline layer. An electronic semiconductor element is constructed using the substrate surface. A wiring layer connects electrodes of the optical semiconductor element and the electronic semiconductor element through the first and the second gentle slopes.	7
This application is a division of application Ser. No. 08/359,695 filed Dec. 20, 1994, now U.S. Pat. No. 5,612,320, which in turn is a continuation-in-part of application Ser. No. 08/168,492, filed Dec. 22, 1993 now abandoned. FIELD OF THE INVENTION The present invention relates generally to novel therapeutic compositions comprising carbohydrate blends and to methods of using the foregoing for the treatment of premenstrual syndrome (PMS). BACKGROUND OF THE INVENTION Each month, for a few days prior to the onset of menstruation, many millions of otherwise-healthy American women develop symptoms of disturbed mood and appetite that can be strikingly similar to those reported by patients with Seasonal Affective Disorder (SAD), carbohydrate-craving obesity, or the non-anorexia variants of bulimia. This syndrome was first termed "premenstrual tension" by R. T. Frank in 1931 and is a very common phenomenon. According to Guy Abraham of UCLA, ". . . of every ten patients to walk into a gynecologist's office, three or four will suffer from premenstrual tension . . . ", and in some the symptoms will be of such severity as to include attempts at suicide. Current Progress in Obstetrics and Gynecology, 3:5-39 (1980). Initial descriptions of the Premenstrual Syndrome (PMS) focused on its association with "nervous tension", headache, and weight gain. The weight gain observed initially was attributed to excessive retention of salt and water, which does indeed occur in some PMS patients. However, it soon became evident that it was also a consequence of the widespread tendency of PMS individuals to crave and over-consume carbohydrates, particularly foods with a sweet taste. PMS is also now referred to as late luteal phase syndrome. D.N.S. III, Revised, American Psychiatric Association (1987). There have been numerous suggestions made about the etiology of PMS. For example, some hypothesized that it was caused by a uterine toxin. Others suggested its cause to be over-consumption of sweets, which presumably is followed by excessive insulin secretion, hypoglycemia, and inadequate brain glucose and results in the oft observed depression and anxiety. It also has been postulated that the behavioral symptoms result from tissue edema and that the psychological changes result from feelings of loss or the social complexities generated by the discomforts of menstruation. However, none of these theories has been substantiated. PMS can persist after hysterectomy and, hence, uterine toxins cannot be its cause. The hyperinsulinism of PMS is not associated with low blood glucose levels, and is probably the consequence of a behavioral aberration (i.e., the tendency of premenstrual women to choose high-carbohydrate diets, which potentiate insulin secretion) rather than the cause. The mood and appetitive changes of PMS are poorly correlated with the tissue swelling; and subhuman primates who are presumably exempt from the psychodynamic or social complexities of human life, also exhibit characteristic behavioral changes premenstrually. There have been many treatments suggested for overcoming or reducing the symptoms of PMS. Many of these are pharmaceuticals such as vitamin supplements, ovarian hormones, detoxifying agents, and diuretics. Other, non-pharmaceutical treatments include carbohydrate-free diets and irradiation of the ovaries and pituitary. These approaches all have had limited success, however. Currently there is no means of treating the mood and appetite disturbances commonly experienced on a recurring basis by a large number of women. Such a treatment would be of great benefit. The present invention is directed to addressing these, as well as other, important needs. Serotonin disturbance and/or deficiency is emerging as a leading theory behind the symptoms of PMS. A number of studies have shown that women with PMS have lower serotonin levels than women without PMS. In mammals, the amino acid tryptophan is the precursor to serotonin synthesis in the brain. Certain carbohydrates when ingested can increase the ratio of tryptophan to large neutral amino acids (T:LNAA) in the blood stream. This increase of T:LNAA allows a higher level of tryptophan to enter the brain, which is necessary for increasing serotonin synthesis. While carbohydrates from normal food can shift this T:LNAA ratio to a limited extent, these normal foods also contain fats and other fibers, both of which slow down digestion and otherwise interfere with the necessary shift in the balance of amino acids in the blood. This invention provides novel carbohydrate blends comprising simple carbohydrates that are rapidly digested and thereby provide relief from the symptoms of PMS, much faster than relief from "normal food". SUMMARY OF THE INVENTION The present invention is directed generally to novel therapeutic compositions comprising rapidly-digestible carbohydrate blends, and to methods of using same for the treatment, prevention, amelioration, or dietary management of PMS. Administration of a composition according to the method of the present invention is of great benefit to women who experience disturbances of mood and/or appetite prior to onset of their menstrual period, as the composition, by supplying particular nutrients for the dietary management of PMS, acts to alleviate and/or prevent such adverse premenstrual symptoms. Specifically, in one embodiment, the present invention is directed to therapeutic compositions useful for the treatment, prevention or dietary management of PMS, comprising novel blends of carbohydrates, such as, but not limited to, dextrose, galactose, pre-gelatinized starch, mannose, sucrose, maltose, lactose, dextrin, maltodextrin, mixtures thereof, and which are essentially free of and not more than 1-2 grams of fat. Preferably, said therapeutic compositions include carbohydrate blends comprising about 20-100 g of a rapidly-digestible carbohydrate blend in solution essentially free of protein, wherein the solution comprises a ratio of about 3-12 mL water to about total 1 g carbohydrate blend and an acidulant selected from the group consisting of adipic acid, citric acid, fumaric acid, lactic acid, succinic acid, tartaric acid, ascorbic acid, acetic acid, and malic acid, to maintain a therapeutically effective pH at less than 6 and wherein the carbohydrate blend comprises about 60-100% dextrose, dextrin, maltodextrin, or a mixture thereof, and 0 to 40% starch or pre-gelatinized starch, or a mixture thereof. More preferable said carbohydrate blends comprise novel mixtures of dextrose and starch, particularly in ratios of about 80% to 100% dextrose to 0 to 20% starch, wherein the total amount of carbohydrate in said blend comprises about 40-80 grams. Still more preferred are compositions comprising carbohydrate blends of dextrose and starch in ratios of about 80% to 85% dextrose to 15 to 20% starch. Specifically preferred is a composition comprising a carbohydrate blend of 45 g dextrose and 3 g starch. In another embodiment, said carbohydrate blends are in the form of a solution comprising dextrose, starch and water. Preferably, the solution comprises about 2-10 mL of water to 1 gram of carbohydrate blend. More preferably, the solution comprises about 5-6 mL water to 1 gram of carbohydrate blend. A further embodiment of the invention is directed to compositions wherein the solution further comprises an acidulant to maintain a therapeutically effective pH at less than 6. Such acidulants include, but are not limited to, adipic acid, citric acid, fumaric acid, lactic acid, succinic acid, tartaric acid, ascorbic acid, acetic acid, and malic acid. Preferred are solutions with a pH between about 2 and 5. More preferred is a solution comprising 60 g dextrose and 10 g galactose, 280 mL water and malic acid to maintain the solution at a pH of 2. Another embodiment of the invention is directed to methods of using said therapeutic compositions for treating, preventing, ameliorating, or managing the effects of PMS. Such methods comprise administering a therapeutically effective amount of said novel compositions to subjects in need of such treatment. Without limiting the invention, and by way of theoretical hypothesis only, it is believed that such therapeutic compositions are effective by increasing the ratio of T:LNAA in the blood stream thereby increasing the level of serotonin production in the brain. Such increase is believed to relieve those PMS conditions related to serotonin and brain functioning by supplying the nutrients necessary for serotonin synthesis. A further embodiment of the invention is the method of treating, ameliorating, preventing or managing the symptoms of PMS comprising administering a combination of novel carbohydrate blend compositions of the present invention together with other useful agents, such as but not limited to vitamins; tryptophan, tyrosine, and other amino acids; ovarian hormones; detoxifying agents and/or diuretics. It is also conceivable that novel compositions of present invention could potentially be useful for the treatment of other symptoms and disorders such as appetite control including carbohydrate craving and binge eating; anxiety and depression and smoking disorders in a subject. DETAILED DESCRIPTION OF THE INVENTION The invention describes novel, rapidly-digestible, carbohydrate blend compositions effective to relieve, treat, ameliorate or manage, the symptoms of PMS. The compositions of the present invention comprise 40 to 100% dextrose and 0 to 60% starch, or any other carbohydrate in the carbohydrate blend solution. The more preferred blend is about 80% dextrose and 20% starch. The choice of a particular ratio will depend upon several factors such as the weight of the individual, the rate of effect the carbohydrates have on the subject and the nature and severity of the PMS symptoms or the manner in which the carbohydrate blend is used. The phrases "carbohydrate blend" or "blend", as used herein and in the claims, refer to mixtures of simple or complex, rapidly-digestible carbohydrates such as, but not limited to, dextrose, galactose, pre-gelatinized starch, mannose, sucrose, maltose, lactose, dextrin, maltodextrin. In a preferred embodiment of the invention, the carbohydrate blend comprises dextrose and starch. The term "dextrose" as used herein and in the claims refers to glucose or polymers thereof. Carbohydrates of the present invention can be obtained from a variety of commercial sources. However, lactose is comprised of 50% dextrose and 50% galactose and galactose is currently only available when lactose is digested. Galactose may be obtained by a process comprising the steps of hydrolysing lactose, crystallizing the products, drying the products and adjusting the ratio of dextrose to galactose by adding anhydrous dextrose. More preferred is the process wherein the hydrolysing step comprises acid or lactase enzymatic hydrolysis. Also more preferred is the process wherein the crystallization step comprises selectively and separately crystallizing the products dextrose and galactose or crystallizing both dextrose and galactose together. The term "solution" as used herein and in the claims, refers to mixtures of carbohydrate blends in water. The term "water", as used herein and in the claims, includes distilled, deionized, or tap water. Preferred is a solution further comprising an acidulant, to maintain a therapeutically effective pH below about 6. The term "acidulant", as used herein, includes acids which can maintain a therapeutically effective pH of the solution. Such acids include but are not limited to adipic acid, citric acid, fumaric acid, lactic acid, succinic acid, tartaric acid, ascorbic acid, acetic acid, and malic acid. Preferred is the acidulant malic acid. The phrase "therapeutically effective" as used herein and in the claims refers to that amount of carbohydrate blend necessary to administer to a subject to induce the desired effect of treating, ameliorating, relieving, or managing the symptoms of PMS. Yet another embodiment of the invention is directed to a method of treating PMS comprising the administration such novel compositions. Such method comprises administering said therapeutic composition to an individual, prior to the onset of her menstrual period, in a quantity sufficient to reduce, ameliorate, manage or prevent the mood and/or appetite disturbances, and/or to suppress the weight gain, which otherwise would be observed in the individual prior to onset of menstruation. One or more of the compositions of this invention can be administered for the treatment of PMS by any means that produces contact of the active agent with the agent's site of action in the body of a mammal. Preferably, the compositions are administered orally. They can be administered by any conventional means available for use in conjunction with therapeutic or dietary agents. They can be administered alone, but generally administered with a carrier selected on the basis of the chosen route of administration and standard therapeutic practice. The dosage administered will, of course, vary depending upon known factors, such as the pharmacodynamic characteristics of the particular agent and its mode and route of administration; the age, health and weight of the recipient; the nature and extent of the symptoms; the kind of concurrent treatment; the frequency of treatment; and the effect desired. A daily dosage of active ingredient can be expected to be about 20-100 g, with the preferred dose being about 40-60 g. The length of time during which a therapeutic compositions will be given varies on an individual basis, but will generally begin 1 to 14 days prior to menstruation and may continue for several days (e.g., 3 days) after onset of menstruation. Dosage forms (compositions suitable for administration contain) from about 20-100 g of active ingredient per unit. In these therapeutic compositions the active ingredient will ordinarily be present in an amount of about 0.5-95% by weight based on the total weight of the composition. The active ingredient can be administered orally in solid dosage forms, such as capsules, tablets, and powders when taken with a suitable amount of water, or in liquid dosage forms, such as elixirs, syrups, and suspensions so long as the proper ratios of ingredients are maintained. Gelatin capsules contain the active ingredient and other powdered carriers, such as cellulose derivatives, magnesium stearate, stearic acid, and the like. Similar diluents can be used to make compressed tablets. Both tablets and capsules can be manufactured as sustained release products to provide for continuous release of agent over a period of hours. Compressed tablets can be sugar coated or film coated to mask any unpleasant taste and protect the tablet from the atmosphere, or enteric coated for selective disintegration in the gastrointestinal tract. Further, the therapeutic compositions can also be prepared in the form of a food-stuff. Such forms include but are not limited to: a cold or hot beverage, soup, pudding, wafer, candy, a snack bar, or other snack, etc. Various colorings and flavorings can be employed in any of the above-mentioned dosage forms to improve the taste of the therapeutic composition to increase patient acceptance, and to make it more palatable. Such flavorings can include but are not limited to artificial or real: chocolate, vanilla, strawberry, coffee, banana, orange, etc. In these various forms, the compositions can be combined with additional substances, such as those needed to serve as fillers, diluents, binders, flavorings or coloring agents or coating materials. EXAMPLE 1 "Composition A": 44.5 g of dextrose, 3 g starch, 1.4 g malic acid, pH 2, 270 mL water, orange flavoring. EXAMPLE 2 60 g dextrose, pH 5, 180 mL water. EXAMPLE 3 60 g dextrose, pH 2, 360 mL water. EXAMPLE 4 30 g dextrose, pH 2, 360 mL water. EXAMPLE 5 HUMAN EFFICACY TEST Carbohydrate blends of present invention or a placebo solution were tested in subjects with PMS over four menstrual cycles. This study was a randomized, iso-caloric placebo-controlled, double-blind study using a Latin Square cross-over design. The study also incorporated a "matched-samples" group design in which the different testing groups had a similar average magnitude and variance with respect to PMS severity. In order to minimize placebo and first time expectation effects; reduce variability; and increase the power of the experimental design, the study utilized a "Latin Square cross-over" group design after placebo run-in, where the subjects received the iso-caloric placebo during the first test month, and then assigned to one of the treatment arms during the second month, and were finally crossed-over during the third and fourth months. A detailed explanation of the methods, measures, and procedures used to accomplish this follows. At various times before and after therapy, subjects completed a standard questionnaire entitled Profile of Mood States (POMS) as described in McNair et al., Profile of Mood States Manual (1971/1981), San Diego: Educational and Industrial Testing Service, which is incorporated herein by reference in its entirety. The POMS test is a well accepted adjective rating test which was designed to measure multiple dimensions of affect. Six groups of women with PMS were tested over four menstrual cycles. The subjects were women who were diagnosed with premenstrual syndrome through an Admissions Form, a Health History Form, a Menstrual Symptomatology Questionnaire, a PMS Profile form, and a PMS Symptomatology Calendar (or Daily Diary) recorded on a daily basis. Subjects were considered to be suffering from PMS by consistent worsening of her appetite, mood and impairment ratings during the luteal phase of her cycles. All subjects received placebo during the first test month and then were placed into one of six treatment arms during the second month and finally crossed over during the third and fourth months. During the final 3 months, they received in a double-bind methodology, either a placebo or a carbohydrate blend of the present invention. Subjects in each group were matched according to their follicular and luteal menstrual distress scores obtained in the first month. This ensured that subjects experiencing relatively similar premenstrual distress were placed in each treatment arm. During the follicular phase, subjects filled out a diary each day and mailed the week's completed form to the study office; during the luteal phase they phoned in their scores each evening. This allowed the study personnel to monitor more closely daily variability and consistency in luteal phase scores. Subjects were tested away from the study site, either in their workplace or at home. They, however, had frequent personal and telephone contact with study personnel prior to and during the testing process. Acute and chronic effects of each test article were measured using a 29-question PMS Symptomatology Calendar, the Day-4 Acute Appetite, Mood and Cognition tests, and an End-of-Month Questionnaire in which each subject recorded their own subjective observations of the therapy's efficacy. Specific descriptions of the acute measures is given in Table 1. TABLE 1______________________________________ACUTE MEASURESSymptom Measure______________________________________Appetite Appetite Questionnaire. A 4-question test using a 10-point scaleMood Modified Profile of Mood States (POMS). A 26-question test using a 5-point rating scale Modified Visual Analog Mood Scale (VAMS). A 12-question test using a 10-point scale Misery Index. An overall emotional functioning rating on a 10-point scale scored as relative to the subjects' worst PMS experience These are tests rating memory, as well as analytical and verbal capability, and may be sensitive to menstrual cycle.Cognition Paced Auditory Serial Addition Test. Recurrent Consonant Trigrams. Controlled Oral Work Association.______________________________________ Specific descriptions of the chronic measures are given in Table 2. TABLE 2______________________________________CHRONIC MEASURESMeasure Description______________________________________PMS The PMS Symptomatology Calendar wasSymptomatology completed in writing during the follicular phaseCalendar of each subject's cycle and completed over the(Daily Diary) telephone during each subject's luteal phase (the telephone was used during the more critical luteal phase to ensure that subjects did not wait until a later day to fill out their calendars). The calendar utilized a 6- point scale that consisted of the following: Appetite. 4 questions Mood. 15 questions Impairment. 3 questions Physical. 4 questions Exclusion criteria. 3 questions concerning illness, medication, or stress The mood questions included sleepiness as a symptom that will allow monitoring of that symptom on a chronic basis.Day-4 Acute Acute tests were taken on both the first andTesting fourth day each month that the subject received therapy. A comparison was made between the subject's scores on the first and fourth days to assess chronic effect of the intervention.End of Month A 6-question, self assessment was made byQuestionnaire each subject as to how well the therapy worked each month in relieving her PMS symptoms (i.e., overall, appetite, mood, cognition, impairment, and physical symptoms).______________________________________ Procedures Subjects entered the study on the day following the onset of menses. They were then monitored and administered the compositions through four menstrual cycles. During all days after the onset of menses and prior to ovulation, the follicular phase schedule was followed and during all days post ovulation and prior to menses, the luteal phase schedule was followed. Determination of the luteal phase of the cycle was done using an ovulation kit. Approximately seven days after ovulation, the subject entered the late luteal phase of the cycle. The specific procedure for these phases are as follows: --Follicular phase schedule. The schedule outline in Table 3 was followed by subjects during the follicular phase of their cycle, during the first two months only, to establish appropriate baselines for the subjects. The appetite, mood, and cognitive tests was administered at 5:30 PM, because these corresponded to the times that tests were taken during the luteal phase, and represented the time that composition efficacy was expected to be greatest, (i.e. 1.5 hours after composition was consumed at 4:00 PM). Subjects came to the study office prior to the first at-home follicular test day, and were given these tests in person to remove practice effects. Subjects were instructed on the use of the ovulation kit at the same time. Test products were given to the subject along with instructions on how to follow the testing procedure and meal plan for the testing days. TABLE 3______________________________________FOLLICULAR PHASE SCHEDULEDay Activity______________________________________Every evening Fill out written PMS symptomatology calendarDay 8 Come to study office and take all tests in person to clarify any questions and remove practice effects. Learn to use an ovulation kit at this time. Take monthly supply of carbohydrate preparations Learn how to follow the testing procedure and meal plan for testing days.Day 9 Call-in for acute appetite, mood, and cognitive tests at 5:30 PM (these times correspond to times tests will be taken during the luteal phase)Day 10 Call-in for acute appetite and mood tests at 5:30 PM (these times correspond to times tests will be taken during the luteal phase).______________________________________ --Luteal phase schedule. The schedule outlined in Table 4 was followed by subjects during the luteal phase of their cycle. The subject's Daily Diary was monitored carefully after ovulation to verify a worsening of mood and determine the appropriate day to begin the 9:00 AM test day screening. TABLE 4______________________________________LUTEAL PHASE SCHEDULEDay Activity______________________________________Every evening Call in PMS symptomatology calendarApproximately Called by investigator at 9:00 AM toseven days after determine severity of premenstrualovulation symptomatology using the POMS and Misery Index measures. • If Delta POMS > 30 (The difference between luteal and follicular scores of the sum of Tension, Depression, anger, and Confusion, or TDAC); and Misery Index > 5: begin Day 1 Intervention. (Since there are 26 TDAC questions with a maximum total score of 104, this represents about a 30% worsening of mood.) • Otherwise: if the severity of the subject's PMS symptoms is not sufficient enough to allow testing, then she will be told that she will be called the next day. • Subjects will not be tested unless they experience their typical PMS symptoms, and if they do not they will be asked to participate in testing during another menstrual cycle until they have been tested during two cycles or they will be dropped from the study.Intervention Follow meal planDay 1 3:45 PM: Call study office for Time = 0, "pre-intervention" 4:00 PM Drink beverage in less than 5 minutes 4:30 PM Call study office for mood and appetite tests 5:30 PM Call study office for mood, appetite, and cognition tests 7:00 PM Call study office for mood and appetite testsIntervention Follow meal planDays 2 and 3 9:00 AM Drink beverage in less than 5 minutes 4:00 PM Drink beverage in less than 5 minutesIntervention 9:00 AM Drink beverage in less thanDay 4 5 minutes 3:45 PM Call study office for Time = 0, "pre- intervention" measurement of mood and appetite 4:00 PM Drink beverage in less than 5 minutes 5:30 PM Call study office for mood, appetite, and cognition testsIntervention Same as intervention Days 2 and 3Day 5 until menses______________________________________ If the subject met the criteria for severity of PMS symptomatology, (i.e., the difference between luteal and follicular scores of the POMS Tension, Depression, Anger, and Confusion scores must be greater than 30 and the Misery Index must be 5 or more), then the subjects entered the first day of that month's testing regimen. (The 4 POMS TDAC scores were used to reduce the number of questions asked of the subject and therefore increase compliance. Fatigue and vigor scores were not being used in the total.) Subjects were not tested unless they experienced their typical PMS symptoms. COMPOSITIONAL INFORMATION The placebo was an iso-caloric mixture of 2 parts carbohydrate and 1 part protein. The volume of both the composition and placebo was similar: 7.5 ounces (about 270 mL). Composition A is a carbohydrate blend of the present invention, Example 1. Composition B is 15 g. casein protein and 32.5 g dextrose. Composition C is 47.5 g of galactose and dextrose (about 83%:17%). During the testing period a meal plan was followed. Meals were consumed at least 3 hours before composition administration and not for 3 hours after administration. Coffee, tea, and other caffeinated beverages were taken as usual. Subjects were allowed only water between meals and during the testing intervals. The composition ingredients were all generally recognized as safe (GRAS) without limitations; the compositions themselves were therefore also GRAS; and the compositions (and the placebo) are formulated in full compliance with all good manufacturing practice regulations of the Food and Drug Administration (FDS). Statistical Analysis This study used a repeated measures Latin Squares design to enable statistical adjustment for anticipated order effects. The first analysis was, therefore, k, a repeated measures analysis of the primary dependent variables with planned comparisons for order effects which was negative. Whether Compositions A, B, or C was given to subjects first, second, or third had no effect on the results obtained for that Composition on any of the dependent variables. Since intersubject variation from cycle to cycle was expected to be large in this population and since T0 score was the criterion for study participation each month, statistical adjustment was made using the T0 score as the covariate. Repeated measures ANOVAs were then conducted using the change from T30 to T90 for the individual Appetite ratings and the change from T90 to T180 for both the total of the scales on the Mood Questionnaire TDAC!, which was the criterion for participation, and, subsequently, for each scale as the dependent variables, and Composition as the repeated measure. Pairwise comparison among adjusted Composition means were tested for significance using a Least Squares procedure. Results MOOD: An average decrease in TDAC from T90 to T180 (adjusted by T0) of 8.78 was seen in subjects after ingesting Composition A. Compositions B and C caused a decrease in TDAC of -1.25 and 0.44 respectively. Repeated measures analyses, by Composition of the difference of scores from T90 to T180 (from the criterion Mood Questionnaire measured, TDAC and adjusted by T0 to control for interindividual variability) showed a significant Main effect by Composition A p<0.04!. Least Squares Means comparisons revealed that this was clearly due to the effect of Composition A in reducing TDAC by an average of 8.78 points, whereas Composition B produced a 1.25 point increase in TDAC and Composition C only a 0.44 decrease over this same time interval. The result obtained with Composition A was statistically significant in comparison to both Composition B p<0.02! and Composition C p<0.04!. There was no difference between Composition B and C. This finding demonstrates that on the criterion mood changes used to define PMS in this study TDAC!, Composition A produced a significant improvement in the subjects' self-perception of their overall mood state. MOOD An average decrease of Anger ratings from T90 to T180 (adjusted by T0) of 4.37 was seen in subjects after ingesting Composition A. Compositions B and C caused a decrease in TDAC of -1.30 and 0.23 respectively. Repeated measures analyses, by Composition of the difference scores from T90 to T180 for the individual mood ratings (adjusted by T0 to control for interindividual variability) showed a significant Main effect by Composition A p<0.02! for the Anger scale. Least Squares Means comparisons revealed that this was due to Composition A being significantly more effective than either Composition B p<0.05! or Composition C p<0.01! in reducing anger ratings from T90 to T180. Average decreases of depression ratings from T90 to T180 (adjusted by T0) for Compositions A, B, and C were 1.77, -0.9, and 0.61 respectively. Average decreases of tension ratings from T90 to T180 (adjusted by T0) for Compositions A, B, and C were 3.17, 0.13, and -0.19 respectively. For Depression and Tension, there was no Main effect by Composition but planned comparisons showed that Composition A appeared more effective than Composition B in reducing Depression ratings from T90 to T180 p<0.05! and showed a trend toward being more effective than either Composition B p<0.09! or Composition C p<0.07! in reducing Tension ratings. There were no significant findings for the subjects' Confusion ratings. APPETITE Repeated measures analyses, by Composition, of the difference scores from T30 to T90 for all of the Appetite variables (adjusted by T0 to control for interindividual variability) showed that there was no Main effect by Composition for subjects' estimate of either their total appetite, fat, protein, or fiber craving. For carbohydrate craving, however there was a significant Main effect by Composition A 0.78, P<0.03! and planned comparisons showed that Composition A was significantly more effective than either Composition B -0.06, P<0.04! or Composition C (-0.44, P<0.01) in reducing carbohydrate cravings from T30 to T90 with late luteal baseline controlled by adjusting for T0. DISCUSSION Results of the POMS questionnaire were evaluated and scored. Compared with placebo, treatment with carbohydrate blends of present invention was associated with an improvement in PMS symptoms as judged by decreases in POMS scores including depression, tension, and anger. These results confirm that, considering a subjects' monthly late luteal variability (T0 Covariate), Composition A was effective in reducing subject's overall late luteal mood rating (TDAC). As this total mood rating was the basis for determining that the subjects were actually experiencing PMS which was sufficiently elevated in comparison to their follicular rating to trigger their participation, these findings can be taken to demonstrate that the compositions of the present invention are beneficial in reducing the mood changes associated with PMS as defined in this study. When the mood scales are analyzed individually, this effect proves to be particularly robust for Anger. There was a significant effect of Composition A in decreasing subjects' late luteal estimates of their Carbohydrate craving at a time of day when appetite ratings and carbohydrate craving in particular might be expected to be increasing. Overall, the findings of this study strongly indicate that the compositions of the present invention treat, ameliorate or manage some of the mood and appetite changes associated with Pre-Menstrual Syndrome. EXAMPLE 4 Blood samples were obtained from subjects at various times before and after consumption of carbohydrate blends of the present invention to determine the ratio of T:LNAA. Subjects administered with Composition A, a carbohydrate blends of the present invention, had a T:LNAA ratio of 0.217+/-0.025 after ingestion compared with a 0.168+/-0.016 pre-ingestion measurements and compared with carbohydrate blends containing proteins and other constituents. Further, there was an earlier onset and greater increase of T:LNAA using blends of the present invention over normal carbohydrates (bagel, juice, or potato). The experimental results show compositions of the present invention comprising novel carbohydrate blends relieve the symptoms of PMS in human subjects. Various modifications of the invention in addition to those shown and described herein will be apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. The foregoing disclosure includes all of the information deemed necessary to enable those skilled in the art to practice the claimed invention. Because the cited applications may provide further useful information these cited materials are hereby incorporated by reference in their entirety.	A method of managing or alleviating carbohydrate craving, binge eating, anxiety, or depression entails administering an aqueous carbohydrate blend containing dextrose, dextrin, maltodextrin or a mixture thereof, and starch, pregelatinized starch, or a mixture thereof. The aquous mixture is essentially free of protein, has a pH of less than 6 and has a ratio of water to carbohydrate blend of about 3-12 mL water to 1 g of carbohydrate blend.	8
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to systems and techniques for modeling and characterizing printed-circuit board wiring, and particularly, to an improved system and method for generating more accurate transmission line models and characterizations for predicting performance of circuits and circuit structures as printed-circuit board transmission data-rates increase. 2. Description of the Prior Art There currently exists limited techniques for providing time and frequency domain measurements from which transmission line models and material parameters for characterizing high frequency performance of printed-circuit board (PCB) conductor structures (i.e., transmission lines) may be extracted. One particular technique, known in the art as short-pulse-propagation, SPP, is a time-domain technique that may be employed to model and characterize performance of circuits and circuit structures. As described in the reference to A. Deutsch, R. S. Krabbenhoft, et al. entitled “Practical Considerations in the Modeling and Characterization of Printed-Circuit Board Wiring”, Digest of SPI'06, Signal Propagation on Interconnects, May 10-13, 2006, Berlin, pp. 1-4, incorporated by reference herein, the SPP technique requires propagating a short, electrical pulse along two identical transmission lines with different lengths, l 1 and l 2 . In current practice, the short pulse is generated by differentiating the step-source of a sampling oscilloscope. FIG. 1 depicts an exemplary prior art measurement apparatus 10 for characterizing high frequency performance of a non-production level (test) PCB showing a short pulse generating source 12 feeding test pulse signals to coaxial probes 16 for differential measurement. The prior art set-up depicted in FIG. 1 is a bench-test set-up configured to conduct a time domain transmission (TDT) measurement technique by launching a short, electrical pulse onto a transmission-line structure on the PCB and measuring the pulse signals to compute characterizing data. In one embodiment, using the test set-up 10 shown in FIG. 1 , the test pulse signals are obtained by differentiating the step-source of a sampling oscilloscope 12 (e.g., an HP model 54120A) using a passive impulse-forming network 17 . In one embodiment, source pulses are, for example, 35 ps and 29 ps (obtained with the Picosecond Pulse Labs pulse generator 4015C and the 5208 network) width and are launched on respective transmission-line structures of different line lengths via test pads formed on the surface of the PCB. High-speed coaxial probes 16 in ground-signal (GS) configuration, (GGB Industries model 40A, 15OLP) are used to connect to the transmission-lines via test pads. In FIG. 1 , a 50-GHz sampling oscilloscope 12 uses a detector channel, e.g., with 2.4 mm connectors and 40 GHz flexible coaxial cables 19 (e.g., Gore GD/AJ, 160-mil-diameter) between the probes 16 and the oscilloscope 15 . Although not shown in FIG. 1 , the test set-up 10 is further configured to provide at the PCB a parallel-plate device by which a low-frequency capacitance measurement may be made by a low frequency impedance analyzer. More particularly, according to the prior art, the line self and mutual capacitances are able to be measured and modeled, e.g., at 1 MHz as is the effective dielectric constant of region around the lines. In accordance with the SPP technique using the apparatus depicted in FIG. 1 , the transmitted pulses are detected and digitized. A time window technique is applied to the pulses to eliminate unwanted reflections from the measurement probes, any contact pads and vias, and cable connectors. In exemplary embodiments, a rectangular time window is used with a smooth transition to the signal baseline steady-state level since the amplitude resolution is more essential than the spectral resolution for this technique. A Fast Fourier Transform (FFT) is performed on the processed waveforms to obtain the complex propagation constant Γ(f) set forth in equation (1): Γ ⁡ ( f ) = α ⁡ ( f ) + j ⁢ ⁢ β ⁡ ( f ) = 1 l 1 - l 2 ⁢ ln ⁡ ( A 1 ⁡ ( f ) A 2 ⁡ ( f ) ) + j ⁢ Φ 1 ⁡ ( f ) - Φ 2 ⁡ ( f ) l 1 - l 2 ( 1 ) where α(f) and β(f) are the attenuation and phase constant, respectively, of the transmission line as a function of frequency (f), and, A i (f) and Φ i (f) are the respective amplitude and the phase of the transforms corresponding to the lines with lengths of l 1 and l 2 and l 1 >l 2 . As referred to herein, frequency is referred to as a variable “f” or “ω”. From the ratio of the two Fourier transforms, the broadband attenuation and phase constant is extracted. No de-embedding or calibration is needed as in frequency-domain based techniques using Vector-Network Analyzers, VNA. The per-unit-length R(f), L(f), C(f), G(f) parameters (R is resistance, L is inductance, C is capacitance, and G is conductance) for the transmission line structure are then calculated using the dimensions obtained by cross sectioning the PCB hardware. This calculation is performed by using an (electromagnetic) field solver that also requires the metal resistivity information of the T-line structures. This metal resistivity information is obtained in accordance with equation (2) by performing a four-point resistance measurement of the two lines and using the actual dimensions, R = ρ ⁢ ⁢ l A ( 2 ) where R is the resistance of the conductor and p is the resistivity, l is the length and A the cross-sectional area of the T-line conductor. The initial calculation of the per-unit-length R(f), L(f), C(f), G(f) parameters for the transmission line structure is performed with an initial estimation of dielectric constant and dielectric loss. For the low frequency range of 10 KHz to 1 MHz, actual measurements of dielectric loss can be made on a large parallel plate structure embedded on the same PCB structure with the signal layer of interest. The dielectric constant “∈” at 1 MHz can be reliably measured from the capacitance measurement on the parallel plate structure of the PCB in accordance with equation (3): C = ɛ 0 ⁢ ɛ r ⁢ A h ( 3 ) where C is the capacitance, ∈ r the relative permittivity, ∈ o the absolute permittivity, A the plate area, and h is the thickness of the dielectric. In current practice, for the signal transmission frequency range between 1 GHz to 50 GHz, an initial guess is made. An electromagnetic field solver is implemented to fit a range of values for the complex permittivity using this initial guess. The attenuation and phase are then calculated based on the R, L, C, G values. The calculated and measured values are compared, and, the procedure is repeated until good agreement is obtained. Each time, the dielectric loss is changed. The field solver generates causal results for C(f) and G(f) based on a Debye model for the complex permittivity: ɛ ⁡ ( ω ) = ɛ ∞ + ∑ i ⁢ ɛ i 1 + j ⁢ ⁢ ω ⁢ ⁢ τ i ( 4 ) where ∈ i ∈ ∞ and τ i are parameters or the expansion in accordance with the Debye model. The final C(f) and G(f) are used, together with the measured ∈ r and the calculated C at 1 MHz, to obtain a measure of the broadband complex permittivity in accordance with equations (5). ɛ r ⁡ ( ω ) = ( C ⁡ ( ω ) C 1 ⁢ ⁢ MHz ) × ɛ r ⁢ ⁢ 1 ⁢ ⁢ MHz ⁢ ⁢ tan ⁢ ⁢ δ ⁡ ( ω ) = G ⁡ ( ω ) ω ⁢ ⁢ C ⁡ ( ω ) ( 5 ) where ω is the frequency and tan δ a measure of dielectric loss. The broadband characteristic impedance Z o is now obtained from equation (6): Z 0 = Γ ⁡ ( ω ) G ⁡ ( ω ) + j ⁢ ⁢ ω ⁢ ⁢ C ⁡ ( ω ) ( 6 ) It is the case that typical VNA based measurements can generally obtain attenuation and phase, especially for high frequency range, but Z o (f) cannot be extracted due to the large discontinuities found in realistic multi-layer printed-circuit-boards, PCBs. As was demonstrated in the reference to T-M. Winkel, et al., entitled, “Comparison of Time- and Frequency-Domain Measurement Results for Product Related Card and MCM Transmission Lines up to 65 GHz”, Proc. Dig. IEEE 14 th Top. Mtg Elec. Perf. of Electronic Packaging, Austin, Tex., Oct. 24-26, 2005, pp. 21-24, the current de-embedding and calibration techniques cannot compensate for the large end effects, i.e., the capacitance, resistance, inductance of the via, test pads, and probes. As data rates transmitted on printed-circuit-boards increase from 2 Gbps to 20 Gbps and beyond, there is required more accurate and causal transmission line models for predicting system performance. Non-causal models can cause inaccurate signal integrity and timing prediction and simulator convergence problem. In order to generate broadband causal models (DC to ˜50 GHz) there is needed higher accuracy and higher-bandwidth measurements of dielectric constant ∈ r (f) and dielectric loss tan δ(f). Single value ∈ r and tan δ that are typically supplied by vendors cannot generate causal models. The current practice for monitoring the integrity of production level printed-circuit boards is to measure the Z o obtained from TDR measurements using a single, hand-held probe. One such prior art probe for TDR measurements is a hand-held probe 80 provided by Polar Instruments Ltd. (Beaverton Oreg.) such as depicted in FIG. 8A with its cover removed. In this embodiment, a Polar generated step source for conducting the TDR measurement has an approximate 120 ps-200 ps rise-time. Additionally, a 10 mil pitch coaxial probe 85 additionally shown in FIG. 7A can also be used for high-speed measurements as these types of coaxial probes may generate 1 ps-35 ps transitions. Further, the hand-held probes 80 include the probe tips 87 depicted in FIG. 7B with a 100 mil pitch as shown in close-up view. Thus, currently, ∈ r and tan δ values are generally supplied only at a few frequencies and measured on simple, non-representative structures. However, it is the case that such measurements are required to be made on multi-layer configurations and the data is needed over a wide frequency range such as from DC to 50 GHz. In addition, as higher-performance systems need the development of lower loss materials, these new materials need to be analyzed in representative, multi-layer structures. Furthermore, concerns to be considered such as losses due to roughness that could become significant, in the order of 5-50% loss increase at 5 GHz, for example. Further considerations to be accounted for include: moisture absorption of new materials that impacts reliability. Further, lead-free compatibility imposes manufacturing constraints that impact electrical characteristics. Moreover, simple TDR production-level Z o process monitors need to be improved because such techniques overpredict Z o due to losses on the board wiring. Overprediction of Z o affects board design, cost, wireability, and system power. Thus, Z o extraction needs to be extended to broadband phase constant Γ(f) and broadband characteristic impedance Z o (f). It would be highly desirable to provide an improved test apparatus that can extend this measurement capability to multi-layer production level PCB boards by providing at least two lines of different lengths and utilizing better probes, improved structures, and instrumentation. It is desired that such improved testability further maintain the ruggedness commensurate with production level testing. SUMMARY OF THE INVENTION The present invention is directed to a system and methodology that incorporates advanced measurement techniques for extracting electrical characteristics of interconnects on multi-layer production level printed circuit boards. Bringing such test capability into the production environment is currently unique to this methodology which includes incorporating, on large multi-layer production level PCB boards, a simple structure that includes the lines of different lengths. Only a minimum of two such lines are needed. For full characterization, a large circular plate is also added to the large multi-layer production level PCB board. According to an aspect of the present invention, there is provided a system and method of testing a multi-level printed circuit board (PCB) having one or more layers of conductors carrying signals at or exceeding Gigahertz frequencies. The testing method comprises: providing, at a layer of the multi-level PCB board, a test structure comprising: a first conductor line, of x length and a second conductor line formed at a same layer of y length where x>y; and, each first and second conductor line having respective capture pad termination at each end; and, a plated via through hole extending between a formed surface test pad connector at a surface of the PCB for electrically coupling respective first and second capture pad terminations at each line end to a respective surface test pad connector provided at a PCB surface, each test pad connector configured for electrical coupling to an RF connector device at the PCB board surface, automatically coupling a first RF connector device to a respective surface test pad connector via an RF connector device at a first end of a conductor line and a second RF connector device to a respective surface test pad connector at a second end a conductor line; automatically configuring a testing apparatus for testing the conductor line formed at the layer by inputting signals at a first end of the conducting line via the first RF connector device coupled to a first surface test pad connector at a PCB surface and, measuring signals at a second end of the conducting line via the second RF connector device coupled to a second surface test pad connector at the PCB surface, the testing implementing a time-domain Short Pulse Propagation (SPP) technique; and, processing, at a computing device, the measured signals for modeling performance of the PCB when operating in excess of Gigahertz frequencies. Further to this aspect of the invention, the testing apparatus comprises first and second mounting devices rigidly holding the first and second RF connector devices, a platform for engaging the multi-level PCB, and an indexing means carrying for automatically aligning the platform carrying the multi-level PCB with the first and second RF connector devices and automatically coupling the first and second RF connector devices to respective first and second surface test pad structures. Alternatively, the testing apparatus comprises first and second robotic manipulator arms holding respective the first and second RF connector devices, the method further comprising: automatically coupling the first and second RF connector devices held by the robotic arms to respective surface test pad structures of the multi-level PCB. In a further aspect of the invention, a portion of the plated via through hole extending between a formed surface test pad connector at one of a top or bottom PCB surface and a conductor line capture pad at a signal line layer beneath the PCB surface includes a stub portion, the test method further comprising: during the testing, coupling the RF connector devices to a surface test pad connector that minimizes a length of the stub portion. In one embodiment, the PCB is a production-level PCB, the computing device processing the measured signals for extracting a broadband propagation constant and characteristic impedance of the conductor line structures useful for the performance modeling. In one embodiment, the PCB is a production-level PCB, the computing device processing said measured signals for extracting a broadband attenuation and phase constant of said conductor line structures useful for said performance modeling. According to another aspect of the invention, there is provided a test structure for facilitating performance testing of a multi-level printed circuit board (PCB) having one or more layers of conductors carrying signals at or exceeding Gigahertz frequencies, the testing structure comprises: a first conductor line formed at a layer of the multi-level PCB board, of x length and a second conductor line formed at a same layer of the multi-level PCB board, of y length where x>y; and, each first and second conductor line having respective capture pad termination at each end; and, a plated via through hole extending between a formed surface test pad connector at a surface of the PCB for electrically coupling respective first and second capture pad terminations at each line end to a respective surface test pad connector provided at a PCB surface, each test pad connector configured for electrical coupling to an RF connector device at the PCB board surface, wherein a test apparatus models performance of the PCB when operating in excess of Gigahertz frequencies by coupling signals to and from a conductor line via the RF connector device and automatically performing a time domain single pulse propagation measurement of the conductor lines at a PCB layer. The test structure further comprises: formed at the same layer of the multi-level PCB board, a capacitor structure having corresponding surface test pad structure being electrically coupled to the capacitor structure through a respective plated via through hole and configured for electrical coupling to the RF connector device. In one embodiment, the plated via through hole extends between front and back PCB surfaces, a test pad connector provided at both front and back PCB board surfaces. Further, the first and second conducting lines are each formed at multiple layers of a PCB, each conductor line at each layer having a respectively formed PTH via connection to a respective test pad connector formed at a PCB surface. Further, a portion of the plated via through hole extending between a formed surface test pad connector at one of a top or bottom PCB surface and a conductor line capture pad at a signal line layer beneath the PCB surface includes a stub portion, wherein, during the testing, the RF connector devices coupled to a surface test pad connector that minimizes a length of the stub portion. According to a further aspect of the invention, there is provided a method of forming a test structure for a multi-level printed circuit board (PCB) having one or more layers of conductors carrying signals at or exceeding Gigahertz frequencies, the method comprising: forming at a layer of the PCB board, a first conductor line of x length and a second conductor line of y length where x>y; and, each first and second conductor line having respective capture pad termination at each end; forming, at each top and bottom PCB surface, a respective surface test pad connector structure in alignment with a corresponding capture pad termination at each conductor line end, and configured for electrical coupling to an RF connector device at the PCB board surface; forming a respective via through hole extending between a formed surface test pad connector at the top and bottom surfaces of the PCB, the formed via hole intersecting a respective capture pad termination of each the conductor line; and, plating the via through hole for electrically coupling a respective first and second capture pad termination of a conductor line to a respective surface test pad connector. Advantageously, the system and method of the present invention enables testing of PCBs in a production level environment. In such environments, very thick boards are tested with very long plated through-hole (PTH) vias. Testing may be performed on many boards within short time by operators who are not familiar with advanced, delicate measurement technique. The set-up is automated or semi-automated for large volume, fast testing and robust for rough handling. BRIEF DESCRIPTION OF THE FIGURES The features and advantages of the present invention will become apparent to one skilled in the art, in view of the following detailed description taken in combination with the attached drawings, in which: FIG. 1 is a prior art depiction of a bench test set-up 10 for providing and measuring short pulses propagated on transmission line structures in an example application of an SPP technique; FIG. 2 is a plot 20 depicting two short pulses propagated on the transmission lines in an example application of the SPP technique utilizing the production-level test set-up of FIGS. 13A , 13 B in one embodiment of the invention; FIG. 3 is an example plot depicting an example measured and fitted attenuation (dB/cm) up to 50 GHz for an example PCB transmission line structure using the production-level test set-up of FIGS. 13A , 13 B in one embodiment of the invention; FIG. 4 is an example plot depicting an example fitted and measured phase constant (1/cm) up to 50 GHz for an example PCB transmission line structure using the production-level test set-up of FIGS. 13A , 13 B in one embodiment of the invention; FIG. 5 is an example plot depicting the extracted broadband permittivity ∈(ω) up to 50 GHz for the example PCB transmission line structure using the production-level test set-up of FIGS. 13A , 13 B in one embodiment of the invention; FIG. 6 is an example plot depicting an example extracted broadband characteristic impedance (Ohms) as a function of frequency showing both real and imaginary components in an example implementation of the SPP measurement techniques employed in the production-level test set-up of FIGS. 13A , 13 B; FIG. 7A depicts a 100 mil pitch bandheld coaxial probe; and, FIG. 7B depicts a close up view of the 100 mil pitch tips used for high-speed measurements in accordance with the prior art; FIG. 8 is in top view of a test coupon structure having various line lengths and parallel plate structure according to one embodiment of the invention; FIG. 9A shows an enlarged close-up view of an example top view of a test pad structure for connecting to an RF connector device formed at the top surface of the PCB; and, FIG. 9B shows an enlarged close-up view of an example bottom view of the test pad structure of FIG. 9A , formed at the bottom surface of the PCB; FIG. 10 shows a typical SMA connector in both front and back perspective views; FIG. 11 depicts a side view of an SMA connector showing alignment screws/posts inserted into the SMA connector at respective alignment holes for mating an SMA connector with a test pad provided at each end of the conductor line; FIG. 12 illustrates a production level test set-up depicting a semi-permanent attachment of surface-mount SMA connector functioning as a probe that can easily be mounted and dismounted onto a respective surface test pad according to one aspect of the present invention; FIG. 13 illustrates conceptually an example production level test set up for automated SPP testing of production level PCB using a computer device programmed to implement the methodology depicted in FIG. 15 according to the invention; FIG. 14 is a diagram depicting a cross-sectional view of an example multi-level PCB board including the test coupon and PTH (plated through hole) vias for test measurements according to one aspect of the invention; FIG. 15 depicts a methodology 300 for conducting the short-pulse-propagation, SPP, time-domain technique using the test apparatus of FIG. 14 in accordance with the invention; and, FIG. 16 shows a virtual test bench technique 400 that may be used to quantify the performance of a device, evaluate and virtually reconstruct SPP process, and define the allowable fabrication tolerances in production; and, FIG. 17 shows a cross-sectional view of a modeled virtual lossy stripline 410 of FIG. 16 . FIG. 18 depicts and exemplary computer system 500 including one or more processors or processing units, a system memory, and an address/data bus structure that connects various system components together. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the invention consisting of a description of the method employed and the necessary apparatus will now be described. In one embodiment, a system and methodology of incorporating advanced measurement techniques for extracting electrical characteristics of interconnects on multi-layer production level printed circuit boards is provided. Bringing such test capability into the production environment is unique to this methodology. FIG. 8 depicts a top view of a portion of a large production level PCB board 99 . In an example embodiment, the PCB board in FIG. 8 is a large functional board, e.g., about ⅕ to ¼ inches thick and about 20 in. by 14 in. in area, for example, and may comprise a blend of glass fiber weave and epoxy-resin (e.g., bismaleimide triazine (BT)) as a substrate for use in printed circuit board wiring. According to the invention, the production board 99 is manufactured to include a test coupon 100 of small footprint including two or more conducting line structures, each line of different lengths manufactured on the PCB surface 98 . For example, the coupon size may be about 2.54 cm×16 cm having at least two such conducting lines 102 , 104 of 3 cm and 10 cm in length, respectively. As shown in the top view of the PCB of FIG. 8 , the coupon may include additional line structures formed of alternate lengths, e.g., 1 cm, 5 cm, etc. Conductor line materials typically include Cu, however, may include other conductive materials, e.g., alloys of copper. Conductor lines may include transmission lines (T-line) including microstrip and stripline structures capable of carrying digital signals at Gigahertz frequencies. For fill characterization, the coupon structure 100 includes a capacitor structure, e.g. plate 120 having the PCB substrate material as a dielectric. In one embodiment, the capacitor 120 includes a plate structure of a diameter between 50×-100× the height of insulator, e.g., 500-mil in diameter, having probe contacts, such that, a capacitive measurement may be performed at relatively low frequency, e.g., to calculate the dielectric constant. In one embodiment, the capacitor plate structure depicted in FIG. 8 is used for extracting dielectric constant at a frequency of 1 MHz, for example. The insulator between the plate 120 and the ground planes above and below the signal layer is the same as the dielectric with glass fiber composition found around the signal conductors of the stripline. Example dielectric constants at 1 MHz are in the range of 3 to 5. The diameter of the plate is 50-100× the height between the plate and the ground plane. This height is in the range of 3 to 5 mil. The signal line widths are in the range of 3 to 5 mil with thickness of 0.7 to 1.4 mil. FIG. 8 also shows the connection to the ground planes and dummy structures that duplicate the connection to the plate but without the plate present. Both the plate and the dummy structure capacitances are measured and the final capacitance value calculated according to equation (3) is the difference between these two measurements. As further shown in FIG. 8 , each line 102 , 104 of the coupon 100 includes a respective surface test pad 105 , 110 at each respective conductor line end for accommodating an RF/microwave frequency contact used for bandwidth applications (up to ˜50 GHz) as test probes. In accordance with one embodiment of the invention, the testing structure implements high performance SMA-type connectors, however, it is understood that other connectors of coaxial probes can be used. In one example, with a step excitation, the SMA probe can transmit a pulse in the production environment. FIG. 9 shows enlarged close-up views of an example test pad structure 105 connecting a conductor or T-line formed in a test coupon 100 of FIG. 8 and particularly, a single test pad structure 117 shown at a top view of the PCB board (shown in FIG. 9A ) and a test pad structure 119 shown at a bottom view of the PCB board (shown in FIG. 9B ). In one embodiment, for example, each SMA connector test pad 105 , 110 includes alignment holes 112 a, b , for mating with an SMA connector such as SMA connectors 125 shown in both front and back perspective views as depicted in FIG. 10 . The test pad 105 , 110 alignment holes, in one embodiment, may be dimensioned as 1.575 mm [0.062 in] in diameter on, for example, a 6.99 mm [0.275 in] pitch, for accommodating mating of an SMA connector 125 . As shown in FIG. 11 , for testing/measurement, a pair of set screws or other threaded posts 127 a , 127 b are inserted into the SMA connector 125 at each respective alignment hole 112 a , 112 b in order to mate a respective SMA connector with the test pad 105 , 110 provided at each end of the conductor line. In the embodiment depicted in FIG. 11 , a set screw/post that is inserted into the SMA may be dimensioned as 3.175 mm [0.125 in.] in length and 1.473 mm [0.058 in.] in diameter. Thus, in the embodiment depicted in FIG. 11 , the set screws/posts may extend beyond, e.g., protrude 0.89 mm [0.035 in] below the surface of the SMA connector and function as mechanical alignment pins that can be slip-fit into the holes 112 a , 112 b in the card shown in the example test set-up shown in FIG. 12 and enable the SMA to function as a probe, rather than as a bolted permanent SMA connection. FIG. 12 particularly illustrates an example test fixture 150 including a semi-permanent attachment of two surface-mount SMA connectors 125 a , 125 b that can be mounted and dismounted onto a respective test pad 105 , 110 . In one embodiment, the mounting and dismounting may be automated, e.g., performed by lowering or raising the height of a holding base or platform 152 upon which the PCB board 99 under test is mounted. That is, in one embodiment, during a PCB production level test run, an indexing mechanism (not shown) is provided for lifting the board 99 into position, and the respective SMA connectors 125 a , 125 b , which are each rigidly held by a respective mounting arm 135 a , 135 b in spaced apart relation (e.g., 3 cm or 10 cm) to accommodate the particular T-line line lengths of the coupon, is inserted into the holes with the set screws for surface mounting of the SMA connector 125 to a respective test pad. The SMA connectors 125 a,b are themselves electrically coupled to test equipment by attaching RF cabling 140 to a coaxial adaptor 145 that mates with the mounted SMA connector. It is understood that, in an alternative embodiment, the test fixture 150 may provide for the SMA connector to be mounted and dismounted onto a respective coupon test pad by automatically indexing (lowering or raising) a robotic arm holding the SMA connector itself until the held SMA connector itself mates to the test pad formed in the PCB board 99 test coupon. In one embodiment, the test fixture provides robotic/automated manipulators used to automatically place the probes along the surface of the large board. The manipulators are programmed to move along the large surface of the board to get to the correct position. Further, alternatively, the probe arm engaging the SMA connector may be manually indexed for mating the SMA connector within the respective test pad structure of a production level PCB, e.g., using a hand-held type probe (not shown). FIG. 13 illustrates conceptually an example production level test set up for automated SPP testing of production level PCB. That is, the automated production-level testing implements computer device 500 for controlling both the 50-GHz sampling oscilloscope 12 for TDT measurements and a low frequency impedance analyzer 11 for capacitive measurements to perform the SPP production-level test methodology of the invention described in greater detail with respect to FIG. 15 . As mentioned herein above, a small portion of the PCB board space is for the coupon structures. In one embodiment, for a multi-level PCB having functional circuits on various levels, the conductor lines 102 , 104 (or, like conductor “trace” structures) are formed on one or more specific layers. The same pattern is repeated for each layer and placed at various locations to check tolerances, which facilitate use of the coupon 100 that can be probed at the board surface to output data used in the SPP testing. FIG. 14 is a diagram depicting a cross-sectional view of an example PCB board 199 . In the embodiment of PCB 199 depicted, thirteen (13) levels (layers) 201 - 213 are provided with layers 201 , 203 , 205 , 207 , 209 , 211 and 213 being electrical signal conducting layers and layers 202 , 204 , 206 , 208 , 210 and 212 being ground layers or ground planes. Signal conductor lines 201 , 205 , 209 and 213 are signal interconnects in the X-axis direction, for example, while, signal conductor lines 203 , 207 and 211 are signal interconnects in the Y-axis direction, for example. It is understood that each of signal lines 201 , 203 , 205 , 207 , 209 , 211 and 213 are formed in an insulator or substrate material, e.g., a dielectric material 218 such as BT. In one embodiment, the PCB insulator material comprises a composite(s) of a glass-fiber weave embedded in an epoxy resin. In a further aspect of the invention, one or more signal layers of the multi-level PCB 199 is manufactured to have the test site of FIG. 9 including the trace conductors (e.g., T-line structures) of 3 cm and 10 cm length and the capacitive plate structure. The test structure of lines and plate can be on any of the layers 201 , 203 , 205 , 207 , 209 , 211 , and 213 . That is, the test site (coupon) 100 shown in FIG. 9 may be manufactured at one or more of the signal layers of the multi-level PCB. Each test site includes a respective manufactured via connection, such as via connections 215 , 220 for contacting a top layer SMA test pad 119 or bottom layer SMA test pad 117 to both ends of a respective trace. In one embodiment, each via connection 215 , 220 is manufactured as a Plated Through Hole (PTH) connector, particularly, by drilling a respective via hole structure all the way through each layer of the PCB board through so as to contact a trace or specifically, a capture pad or similar metal feature formed at the end of a trace, and then plating the formed via hole with conductive material, e.g., a metal such as copper, to render it as a PTH. As shown in FIG. 14 , each PTH via 215 , 220 extends from layer 201 to layer 213 of PCB 199 and includes as is shown contacting a capture pad 225 connecting a signal line at each end (only 1 is shown) to the test pads 117 , 119 . More particularly, as shown in FIG. 14 , a capture pad 225 is manufactured on the signal layer of interest. In the example PCB 199 depicted in FIG. 14 , capture pads 225 are at the signal layer 203 and 211 . During manufacture, the PCB board is drilled first, the drill preferably having an example tolerance such that the diameter of the capture pad placed on the signal layer is about three times (3×) the via diameter, to ensure that even if the drill shifts, it will land on a large capture pad 225 . For example, in one embodiment, PTH via 215 , 220 may be 12 mil in diameter while the capture pad diameter is 3× this value or more. Then, a conductor material, e.g., copper, is plated on the sides of the drilled via hole in order to malce electrical contact from the top surface test pad to the signal line at the layer of interest. As shown in FIG. 14 , there is additionally provided via stub portions 216 , 221 of the total PTH via length that extends beyond the layer in which the conductor line resides. The length of each respective via stub portions 216 , 221 extending beyond signal layer is shown in broken circles. That is, stub portions 216 , 221 are the PTH via length portions from the capture pad 225 at a layer of interest, such as 211 or 203 , to the open end of PTH formed at the bottom surface of the PCB or such as layer 213 and pad 117 , or formed at the top of the board on layer 201 and pad 119 when probing is done from test pad 117 and capture pad 225 is used for layer 203 signal. As the bandwidth of the SPP technique implemented in accordance with the invention is dependent on the ability of eliminating the effect of end parasitics by using the time windowing and ratioing of FFTs, it has been found that the length of the plated-through hole (PTH) will have the strongest effect, i.e., the propagated pulses with various via stub conditions. Due to this effect, the back drilling of the vias 215 , 220 is performed as a cost effective means to increase the bandwidth, e.g., for lines placed on the middle layers of PCB boards, especially large PCB boards having typical thicknesses of about 100-200 mil, or more. That is, in one embodiment, after plating the entire via hole, “backdrilling” may be performed to remove a portion of the plated through hole that may be detrimental to accurate high frequency measurements as contributing to a long stub portion. Performing backdrilling to remove a lengthy stub portion of the PTH connected to the trace line will increase the bandwidth of a high-frequency measurement using the SMA connector probe such as contemplated by the invention. Alternate means of reducing the PTH stubs include use of stacks of subcomposites or microvia technologies. Subcomposites are groups of a few layers only that are built independently and then joined with short PTH vias. Other approaches would join these sub-groups with conducting material and not use drilling. In the example multi-level PCB 199 shown in FIG. 14 , capture pads or similar feature 225 are provided at layers 203 or 211 connected to a trace. During testing operation, in one example scenario, the probing for signal line at layer 203 is performed from test pad 117 at layer 213 making the via stub 221 short. On the right side of the PCB depicted in FIG. 14 , the testing for signal line at layer 211 is performed from the test pad 119 on layer 201 making the via stub 216 short. Further, as shown in FIG. 14 , in every layer that PTH via traverses, there is a gap between it and the ground planes referred to as an “antipad”. Metal material is only plated where the actual hole was drilled so that the via does not short to the ground but connects the outside test pad to the inner signal layer. An example signal path for testing, in one embodiment, starts from a test pad, e.g., 119 on the right side of the PCB 199 , down through the PTH via to the layer of interest, e.g., layer 211 , propagate through the signal line at layer 211 on the left side of the PCB 199 , propagate through the PTH on the right and reach a second surface test pad, e.g., test pad 119 on the top left side of the PCB 199 . A line on PCB layer xx will be probed on the left and on the right, for input and output, from the same side of the board, either from layer 201 on both ends, or, from layer 213 on both ends of the line. In alternate embodiment, for lines closer to the top or bottom layers of the PCB, e.g., within 40 mils from the PCB surface, probing is performed such that the stub length is minimal. Thus, for example, in a 10-layer PCB board, for lines in layers 201 - 203 , probing can be done at test pads from the backside of the board, while for layers 211 - 213 , probing is performed from the front of the board. It is understood that, a similar PTH via connection is formed to connect a capacitor structure formed in the test coupon and embedded at a layer of the multi-level PCB to a surface test pad connection structure for connection to an RF connector device when making a capacitive test measurement, e.g., using an LCR multi-frequency meter (e.g., HP model 4275A). Compensation of the PTH stub capacitance can also be made by enlarging the antipad size, further optimizing the launch structure and valid bandwidth of the resulting measurement. The optimal dimension can be determined by performing three dimensional modeling of the structure and simulating the entire measurement flow in a virtual test bench as will be described in greater detail herein below. The physical structure is modeled with a field solver. The equivalent model is then included in SPICE type circuit simulation and virtual short pulse is injected into the two lines with these modeled via ends. The resultant pulses are then used in the signal processing software as if they were measured on actual hardware. The attenuation and phase are then extracted and the bandwidth is determined in a virtual mode. FIG. 15 depicts a methodology 300 for conducting the short-pulse-propagation, SPP, time-domain technique employing the test coupon structure of FIG. 9 on a product-level printed-circuit board such as shown in FIGS. 12 , 13 . A test apparatus configured as depicted in FIGS. 12 and 13 , at a minimum, produces a short, electrical pulse propagating along the two identical transmission lines 102 , 104 with different lengths, l 1 and l 2 at a test coupon provided at any level of the multi-level PCB. The SPP technique is used for both modeling and measurement of representative printed-circuit interconnect characteristics and their relevance for overall system performance. At a base level, the testing may be performed at the 3 cm and 10 cm traces of the test coupon of FIG. 8 to garner information useful for calculating the transmission line attenuation and phase along the copper trace. By including the other structures in the test coupon of FIG. 9 , e.g., capacitor plate 120 , additional information, such as the dielectric complex permittivity, can be extracted in the production environment and the user may incorporate other tests to provide more comprehensive information, e.g., that can be used for high frequency performance modeling. As shown at step 301 , in FIG. 15 , using the line traces in the test coupon structure at any PCB layer, the test method employing the computer or processor device 500 ( FIG. 13 ) implementing first programmed instructions for measuring the conductor's characteristic impedance Zo (not the broadband Zo(f) using a TDR (Time Domain Reffectometry) measurement. This initial screening enables selection of the two lines l 1 and l 2 that have similar Zo. The simple, single-frequency Zo testing of the prior art, is enhanced with the technique of the invention as it is now possible to perform attenuation measurement and ultimately extract the full broadband propagation constant Γ(f) and Zo(f) over the desired frequency range. Thus, at step 303 , a DC measurement is performed to obtain line resistance in accordance with equation (2), and line capacitance at 1 MHz, and plate capacitance and dielectric loss measurements are made in accordance with equations (3) and (5). A time domain transmission (TDT) step 305 , in FIG. 15 , is then performed in order to obtain the two propagated pulses as shown in FIG. 2 implemented in the SPP technique. FIG. 2 is a plot 20 depicting two short pulses 22 , 25 propagated on 2 cm and 8 cm long transmission lines respectively, in a current example application of the SPP technique utilizing the measurement apparatus 150 of FIGS. 12 , 13 . In step 307 , the test equipment is configured to perform GammaZ signal processing of the propagated pulses to obtain the complex propagation constant Γ(f) as set forth in equation (1). This then allows the extraction of the complex permittivity, however, requires test line cross sectioning. At step 309 , the signal lines and parallel plate are cross sectioned at several locations and average dimensions are obtained to perform an initial calculation of the complex permittivity, e.g., at 1 MHz. Continuing in accordance with the invention, the measurements may be extended to their full capability for extracting the full material properties of the insulator being used in the PCB. That is, while the SPP technique can be completed to the stage of extracting both the propagation constant and broadband impedance, the invention further allows the extraction of the complex permittivity. Such a step requires test line cross sectioning, calculation of R, L, C, G parameters with a field solver, measurement of the large plate loss tangent and capacitance at low frequency, and comparing of measured attenuation and phase to calculated values in an iterative manner as shown at step 325 . Thus, continuing at step 310 , FIG. 15 , there is performed the calculation of R(f), L(f), C(f), and G(f) parameters using a causally-enforced field solver, CZ2D such as described in the reference to W. T. Weeks entitled “Calculation of coefficients of capacitance of multiconductor transmission lines in the presence of dielectric interface”, IEEE Trans. Mirowave Theory Tech., vol. MTT-18, pp. 35-43, 1970, and implementing the Debye model from equation (4). This leads to calculating the total attenuation α(f and β(f) at step 312 to extract the broadband complex permittivity in accordance with equation (5) and the characteristic impedance accordance with equation(6). It is understood that the C(f) and G(f) are calculated with CZ2D solver by using an initial set of values for the loss tangent of the dielectric, i.e., tan δ, using the permittivity value measured at 1 MHz as conducted at step 309 , FIG. 15 . Then at step 315 , the α(f) and β(f) complex propagation parameters extracted at step 307 are compared to the α(f) and β(f) values as calculated at step 312 . FIG. 3 is an example plot 40 depicting an example measured and fitted attenuation (dB/cm) as a function of frequency (up to 50 GHz) for an example PCB transmission line structure using the automated production-level test set-up of FIGS. 12 and 13 ; and, FIG. 4 is an example plot 50 depicting an example fitted and measured phase constant (1/cm) as a function of frequency (up to 50 GHz) for an example PCB transmission line structure using the production-level test set-up of FIGS. 12 and 13 . Continuing, at step 316 , a determination is made as to whether the calculated values are acceptable, i.e., a good fit. If the calculated values are not a good fit, the process returns to step 310 to perform the calculation of R, L, C, G parameters with a field solver, and with adjusted parameters of the expansion (e.g., ∈ i ∈ ∞ and τ i ) to improve the fit. Thus, as shown in FIG. 15 , step 325 is understood that a few iterations may be made to fit the α(f) and β(f) complex propagation parameters to the measured values with each iteration adjusting the parameters of the expansion to improve the fit. In this iterative manner, a smooth interpolation and extrapolation is made over the desired frequency range (at step 320 ). Remaining steps 325 are performed to obtain the full model in step 320 , including the step 317 of extracting the complex permittivity, loss tangent, and characteristic impedance over the desired frequency range, e.g., by relying upon equations (5) and (6) and also as explained in the herein incorporated reference to A. Deutsch, et al. entitled, “Extraction of ∈ r (f) and tan δ(f) for Printed Circuit Board Insulators Up to 30 GHz Using the Short-Pulse Propagation Technique”, IEEE Transactions on Advanced packaging, vol. 28, no. 1, pp. 4-12, February 2005. The extracted R(f), L(f), C(f), and G(f) are input to a Spice type circuit simulator to predict pulse and step signal propagation. These simulated waveforms are compared to actual measured TDT signals and step 318 in FIG. 15 completes the correlation process. Since the R(f), L(f), C(f), and G(f) are produced by a field solver that enforces causality and the resultant waveforrns are verified with actual measurements, the transmission line models produced by the complete procedure in FIG. 15 become reliable, predictive models for system performance prediction. For example, FIG. 5 is an example plot 60 depicting the extracted broadband permittivity ∈(ω) as a function of frequency (up to 50 GHz) and FIG. 6 is an example plot 70 depicting an example extracted broadband characteristic impedance (Ohms) as a function of frequency (up to 50 GHz) and showing both real 72 and imaginary 74 components for the example PCB transmission line structure using the production-level test set-up of FIGS. 12 , 13 . The extracted broadband characteristic impedance value is unlike the simple, single value Z o obtained with typical time-domain reflectometry, TDR, measurements. The SPP time-domain technique can successfully be used to extract the broadband permittivity for typical packaging interconnects. The technique is typically used on representative stripline structures built with small interface discontinuities such as pads and vias. A short pulse is injected into the two lines of different lengths. Signal processing of the digitized pulses consists of rectangular time windowing of the unwanted reflections from interface discontinuities and Fourier transformation. From the ratio of the two Fourier transforms the total attenuation α(f) and phase constant β(f) are obtained as shown at step 307 , FIG. 15 . In sum, the SPP technique as described above can be completed to the stage of extracting both the propagation constant and broadband impedance. This then allows the extraction of the complex permittivity. Such a step requires test line cross sectioning, calculation of R, L, C, G parameters with a field solver, measurement of the large plate loss tangent and capacitance at low frequency, and comparing of measured attenuation and phase to calculated values in an iterative manner as shown at step 325 . These steps could be done only on small number of board locations for spot checking of the material characteristics when a new vendor is selected or can be measured on smaller cards with fewer layers. The smaller card would be used in pre-physical build stage to evaluate the performance of the best material for the target system operation. Such smaller cards could be measured with coaxial probes or with the SMA probes and set-up shown in FIGS. 12 and 13 where the bandwidth could be typically extended to 50 GHz. FIG. 16 shows a virtual test bench technique 400 that may be used to quantify the performance of a device to the circuit parameter variation, evaluate and virtually reconstruct SPP process, and define the allowable fabrication tolerances in production. As shown in FIG. 16 , the virtual test bench includes a SPICE simulation technique implementing a programmed computer configured, in one embodiment, as a Virtual Impulse Generator 401 and virtual waveform detector 404 , for simulating inputs pulses 414 and detecting corresponding virtual output pulses 418 of a virtual lossy stripline 410 modeled according to the SPP technique of the invention in the CZ2D solver 415 . That is, the 2-D solver 415 is used to simulate the stripline to obtain line parameter R, L, C, and C as well as α(f). However, the line impedance are affected by the h 1 (mil), h 2 (mil), w (mil), t(mil), ρ(ηΩ.cm), ∈ r, Z 0 (Ω) parameters as shown in the cross-sectional view of the modeled virtual lossy stripline 410 shown in FIG. 17 . For example, it is seen that Z 0 variation impacts the SPP predicted α(f). The difference “Δ” between 2-D solver and SPP is defined equation (7): Δ = α ⁡ ( CZ ⁢ ⁢ 2 ⁢ D ) - α ⁡ ( SPP ) α ⁡ ( CZ ⁢ ⁢ 2 ⁢ D ) ⁢ % ( 7 ) Simulations with the virtual test bench technique were made of the effect of process tolerances on the accuracy of the SPP technique. It was found that the technique is able to discern even +/−1.6% changes in characteristics of the transmission lines. The emulated simulation indicates that TDR screening needs to be done prior to the short-pulse excitation. The SPP technique should not be used with lines having more than +/−10% non-uniformity in impedance along the length. In addition, the two lines used, should not differ in Z 0 by more than 5% in order to obtain the SPP predicted attenuation error to be under 10% and this is why step 301 of line screening is needed. The emulation technique can also be used to verifying the accuracy and capability of measurement techniques and so it is of general applicability. The measurement technique described here can also be used to discern effects such as roughness of metallization (see for example, the reference to Alina Deutsch, et al. entitled “Prediction of Losses Caused by Roughness of Metallization in Printed-Circuit Boards”, IEEE Transactions on Advanced Packaging, Vol. 30, No. 2, May 2007, incorporated by reference herein), inhomogeneities in differential transmission line structures due to the fiber weave absence between the lines (see for example, the reference to Alina Deutsch, et al. entitled “Use of the SPP Technique to Account for Inhomogeneities in Differential Printed-Circuit-Board Wiring” Digest of SPI'08, Signal Propagation on Interconnects, May 12-15, 2008, Avignon, France, pp. 22-26, and incorporated by reference herein) and inhomogeneities in top or bottom microstrip structures that have soldermask layers on top of typical insulator layer. In such cases, a two step technique would be used whereby two sets of cards are built. In the first case a homogeneous card or a smooth card or a card without soldermask is built and measured. In the second step the measurement is repeated but on cards with these additional effects included. The technique can also be used to used whereby two sets of cards are built. In the first case a homogeneous card or a smooth card or a card without soldermask is built and measured. In the second step the measurement is repeated but on cards with these additional effects included. The technique can also be used to fully characterize other transmission line structures used in computer systems, such as cables, chip carrier wiring, and on-chip interconnects. SPP is used to generate broadband predictive models for differential lines with different glass-fiber-to-epoxy-resin ratios and also for the soldermask layers used on top and bottom of typical boards. In both cases, a two-step extraction procedure is employed to obtain the broadband complex permittivity for the inhomogeneous structures and correlation with TDT measurements is used to validate the technique. The present invention can be realized as a combination of hardware and software. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which, when loaded into a computer system, is able to carry out these methods. Computer program means or computer program in the present context include any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after conversion to another language, code or notation, and/or reproduction in a different material form. Thus, the invention includes an article of manufacture which comprises a computer usable medium having computer readable program code means embodied therein for causing a function described above. The computer readable program code means in the article of manufacture comprises computer readable program code means for causing a computer to effect the steps of a method of this invention. Similarly, the present invention may be implemented as a computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing a function described above. The computer readable program code means in the computer program product comprising computer readable program code means for causing a computer to affect one or more functions of this invention. Furthermore, the present invention may be implemented as a program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for causing one or more functions of this invention. The system and method of the present disclosure may be implemented and run on a general-purpose computer or computer system. The computer system may be any type of known or will be known systems and may typically include a processor, memory device, a storage device, input/output devices, internal buses, and/or a communications interface for communicating with other computer systems in conjunction with communication hardware and software, etc. More specifically, as shown in FIG. 18 , a computer system 500 , includes one or more processors or processing units 510 , a system memory 150 , and an address/data bus structure 501 that connects various system components together. For instance, the bus 501 connects the processor 510 to the system memory 550 . The bus 501 can be implemented using any kind of bus structure or combination of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures such as ISA bus, an Enhanced ISA (EISA) bus, and a Peripheral Component Interconnects (PCI) bus or like bus device Additionally, the computer system 500 includes one or more monitors 519 and, operator input devices such as a keyboard, and a pointing device (e.g., a “mouse”) for entering commands and information into computer, data storage devices, and implements an operating system such as Linux, various Unix, Macintosh, MS Windows OS, or others. The computing system 500 additionally includes: computer readable media, including a variety of types of volatile and non-volatile media, each of which can be removable or non-removable. For example, system memory 550 includes computer readable media in the form of volatile memory, such as random access memory (RAM), and non-volatile memory, such as read only memory (ROM). The ROM may include an input/output system (BIOS) that contains the basic routines that help to transfer information between elements within computer device 500 , such as during start-up. The RAM component typically contains data and/or program modules in a form that can be quickly accessed by processing unit. Other kinds of computer storage media include a hard disk drive (not shown) for reading from and writing to a non-removable, non-volatile magnetic media, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a “floppy disk”), and an optical disk drive for reading from and/or writing to a removable, non-volatile optical disk such as a CD-ROM, DVD-ROM, or other optical media. Any hard disk drive, magnetic disk drive, and optical disk drive would be connected to the system bus 501 by one or more data media interfaces (not shown). Alternatively, the hard disk drive, magnetic disk drive, and optical disk drive can be connected to the system bus 501 by a SCSI interface (not shown), or other coupling mechanism. Although not shown, the computer 500 can include other types of computer readable media. Generally, the above-identified computer readable media provide non-volatile storage of computer readable instructions, data structures, program modules, and other data for use by computer 500 . For instance, the readable media can store an operating system (O/S), one or more application programs, and/or other program modules and program data for enabling video editing operations via Graphical User Interface (GUI). Input/output interfaces 545 are provided that couple the input devices to the processing unit 510 . More generally, input devices can be coupled to the computer 500 through any kind of interface and bus structures, such as a parallel port, serial port, universal serial bus (USB) port, etc. The computer environment 500 also includes the display device 519 and a video adapter card 535 that couples the display device 519 to the bus 501 . In addition to the display device 519 , the computer environment 100 can include other output peripheral devices, such as speakers (not shown), a printer, etc. I/O interfaces 545 are used to couple these other output devices to the computer 500 . As mentioned, computer system 500 is adapted to operate in a networked environment using logical connections to one or more computers, such as the server device that may include all of the features discussed above with respect to computer device 500 , or some subset thereof. It is understood that any type of network can be used to couple the computer system 500 with a server device, such as a local area network (LAN), or a wide area network (WAN) (such as the Internet). When implemented in a LAN networking environment, the computer 500 connects to local network via a network interface or adapter 529 . When implemented in a WAN networking environment, the computer 500 connects to the WAN via a high speed cable/dsl modem 580 or some other connection means. The cable/dsl modem 180 can be located internal or external to computer 500 , and can be connected to the bus 501 via the I/O interfaces 545 or other appropriate coupling mechanism. Although not illustrated, the computing environment 500 can provide wireless communication functionality for connecting computer 500 with remote computing device, e.g., an application server (e.g., via modulated radio signals, modulated infrared signals, etc.). The terms “computer system” and “computer network” as may be used in the present application may include a variety of combinations of fixed and/or portable computer hardware, software, peripherals, and storage devices. The computer system may include a plurality of individual components that are networked or otherwise linked to perform collaboratively, or may include one or more stand-alone components. The hardware and software components of the computer system of the present application may include and may be included within fixed and portable devices such as desktop, laptop, and server. A module may be a component of a device, software, program, or system that implements some “functionality”, which can be embodied as software, hardware, firmware, electronic circuitry, or etc. In sum, the system and method of the present invention provides an automated or semi-automated technique for large volume testing of PCBs in a production level environment. In such environments, very thick boards are tested with very long plated through-hole (PTH) vias. Testing may be performed on many boards within short time by operators who are not familiar with advanced, delicate measurement technique. While the invention has been particularly shown and described with respect to illustrative and preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention that should be limited only by the scope of the appended claims.	A system and method for performing a test for characterizing high frequency operation of PCB boards. More particularly, a system and methodology is provided to implement a time-domain short pulse propagation (SPP) technique on the production line, on large, multi-layer, product-level PCB boards, for large volume testing, by people who are not familiar with advanced, delicate, measurement techniques, who need robust test facilities, and cannot afford the time or expense of other lab-type approaches.	6
TECHNICAL FIELD [0001] The invention concerns the implementation of a porous layer in a dye-sensitized solar cell (DSC) and a method for manufacturing a DSC having a porous conducting electrode layer. BACKGROUND [0002] Dye-sensitized solar cells (DSC's) developed by M Grätzel et al are a new type of solar cells made of low-cost materials and can be manufactured by conventional printing techniques, see for example U.S. Pat. No. 5,084,365. [0003] A conventional sandwich type DSC is shown in FIG. 1 . The DSC ( 1 ) has a few micrometer thick porous TiO 2 electrode layer ( 2 ) deposited onto a transparent conducting substrate ( 3 ). The TiO 2 electrode comprises interconnected TiO 2 metal oxide particles dyed by adsorbing dye molecules (typically a Ruthenium polypyridyl complex) on the surface of the TiO 2 particles. The transparent conducting substrate ( 3 ) is normally a transparent conducting oxide (TCO) ( 4 ), for example fluorine-doped tin oxide (FTO), deposited onto a glass substrate ( 5 ). Other types of TCO materials, such as indium tin oxide (ITO), or aluminum doped zinc oxide, or antimony doped tin oxide, are used as well. [0004] The TCO layer ( 4 ) serves the function as a back contact extracting photo-generated electrons from the TiO 2 electrode ( 2 ). The TiO 2 electrode ( 2 ) is in contact with an electrolyte ( 6 ) (typically containing I −/I 3 − ion pairs) and another transparent conducting substrate, i.e., a counter electrode ( 7 ). The TCO layer ( 8 ) of the counter electrode is usually covered with a thin catalytic layer of platinum. The platinum has a strong catalytic effect, facilitating the electron transfer to the electrolyte. [0005] Sunlight is harvested by the dye, producing photo-excited electrons that are injected into the conduction band of the TiO 2 particles and further collected by the conducting substrate ( 8 ). At the same time, I − ions in the redox electrolyte reduce the oxidized dye and transport the generated electron acceptors species (I 3 − ) to the counter electrode where the I 3 − species are reduced to I − . A record 11% power conversion efficiency has been reported, although good quality cells typically provide between 5% and 8%. [0006] The edges of the conducting substrates are usually not deposited with TiO 2 electrode material. The two conducting substrates are sealed at the edges in order to protect the DSC components against the surrounding atmosphere, and to prevent the evaporation or leakage of the DSC components inside the cell. [0007] Due to the low conductivity of the transparent conducting oxide ( 4 , 8 ), the cells ( 1 ) must be deposited in segments or strips with gaps in between. Current collectors are deposited in the gaps to connect the segments or strips to form solar cell modules. The wider the segments the greater the electronic ohmic losses in the TCO layer because of poor TCO conductivity. [0008] The individual cells ( 1 ) are electrically connected in parallel or in series to enhance the DSC current or DSC voltage, respectively. The electrical connection can be made outside the cells using peripheral equipment such as cables or solders. Alternatively, the electrical connection can be made inside the cells by distributing the DSC components in such a way that the desired parallel or series connection of the cells is achieved. [0009] The low conductivity of the transparent conductive oxide, TCO, is a problem as it limits the width of the segments. Another problem is that TCO-based glass is expensive, and the use of two TCO-based glasses in the DSC construction increases the cost even further. In order to resolve these problems, attempts have been made to exchange the TCO-based glass of the back contact by vacuum deposit of a porous conductive metal layer on the TiO 2 by using metal sputtering techniques. Since the deposited sputtered porous metal layer is electrically conductive, the TCO-based glass can be exchanged with a TCO-less glass, which is much cheaper. [0010] In Yohei Kashiwa, Yorikazu Yoshida, and Shuzi Hayase, PHYSICS LETTERS 92, 033308 (2008)) is described electro-spraying of a tetrapod-shaped ZnO onto the TiO 2 layer followed by sputtering of titanium metal on top of the ZnO covered TiO 2 layer. The tetrapod-shaped ZnO, which was embedded in the titanium layer, was then washed away by subsequent ZnO dissolution in HCL in order to form a sufficiently porous titanium layer. The porosity of the titanium layer must be sufficient in order not to create electrolyte ion diffusion limitations with resistive losses as a consequence. Also, the dye-sensitization process can be slowed down due to of diffusion problems through the titanium layer. Consequently, it was necessary to introduce pores in the sputtered titanium layer. The overall light-to-electric energy conversion efficiency obtained was 7.43%. [0011] Yohei Kashiwa, Yorikazu Yoshida, and Shuzi Hayase, PHYSICS LETTERS 92, 033308 (2008)) and US2009314339 describe methods for increasing porosity of vacuum deposited metal layers. In U.S.2009314339 a fine-particle layer is formed on the surface of the porous TiO 2 layer and subsequently a conductive metal film is formed on the surface of the fine-particle layer; and thereafter the fine-particle layer is removed by heating or solvent-cleaning. A sputtered porous titanium layer deposited on top of a TiO 2 layer is also disclosed in J. M. Kroonl, N. J. Bakker, H. J. P. Smit, P. Liska, K. R. Thampi, P. Wang, S. M. Zakeeruddin, M. Graetzel, A. Hinsch, S. Hore, U. Wu{umlaut over ( )}rfel, R. Sastrawan, J. R. Durrant, E. Palomares, H. Pettersson, T. Gruszecki, Walter, K. Skupien and G. E. Tull, Prog. Photovolt: Res. Appl. 2007; 15:1-18 (ENK6-CT2001-00575 NANOMAX). [0012] The overall light-to-electric energy conversion efficiency obtained was 3.6%. These scientists concluded that further research was needed in order to improve efficiency. [0013] Vacuum-based electron beam vapor deposition has been used to deposit a porous titanium layer on top of the TiO 2 layer, Nobuhiro FUKE Japanese Journal of Applied Physics Vol. 46, No. 18, 2007, pp. L420-L422, Back Contact Dye-Sensitized Solar Cells vacuum process; Nobuhiro Fuke, Atsushi Fukui, Ryohichi Komiya, Ashraful Islam, Yasuo Chiba, Masatoshi Yanagida, Ryohsuke Yamanaka, and Liyuan Han, Chem. Mater. 2008, 20, 4974-4979. The overall light-to-electric energy conversion efficiency in these studies was between 7.1 and 8.4%. [0014] Vacuum deposition of metal layers has several disadvantages: Vacuum deposition is slow compared to other techniques, such as printing techniques. Equipment used for vacuum deposition is relatively expensive. Vacuum equipment requires substrates that do not give off gases under vacuum conditions. Vacuum deposited porous metal layers have low permeability for ions in the DSC electrolyte. Vacuum deposited porous metal layers have low permeability for dye-sensitization molecules resulting in longer dye-sensitization times. Vacuum techniques require masking in order to deposit metal particles at the right place in the DSC. Since deposited material is spread non-selectively on the surface the substrate in the deposition chamber, deposited metal material is wasted during deposition. Metal targets used for vacuum deposition are expensive. [0023] Advantages with the vacuum process are that porous metal films with both good mechanical stability and good electrical conductivity can be formed. It is probable that the advantages are partly due to that the vacuum allows for the deposition of pure metal particles in an oxygen-free atmosphere. The absence of oxygen during deposition makes it possible to form good metallic particle-to-particle contact. The particle-to-particle contact is achieved due to the metal particles having high purity and being essentially free from metal oxide on the surface. During sputtering, the substrate is bombarded with high-energy metal particles. The large physical contact area increases the binding energy between the particles and the substrate, and the binding energy in the metal particle-to-particle contact, which results in a strong mechanical adhesion of the metal particles and the substrate and a strong mechanical particle-to-particle adhesion SUMMARY OF THE INVENTION [0024] It is an objective of the present invention to provide a dye-sensitized solar cell, DSC with increased current-handling capability. [0025] It is another objective of the present invention to provide a DSC that involves no or less TCO. [0026] It is a further objective of the present invention to provide a cost-effective method for manufacturing a DSC with a porous conductive powder layer, PCPL. [0027] The objectives of the present invention are met by a DSC comprising a porous conductive powder layer (PCPL), which increases the electrical current-handling capability of the DSC. [0028] The PCPL is formed by depositing an electrically conductive powder (CPL), such as a metal powder, onto a substrate. Mechanical pressure is applied to the porous metal powder layer in order to form a mechanically stable layer and increase the electrical conductivity of the layer. Subsequently, the PCPL can be subjected to heat to further increase the mechanical stability and electrical conductivity. [0029] The metal powder can be in the form of a compound of the metal when deposited. The compound is thereafter treated to undergo a reaction so that the metal is formed. The treatment can be a heat treatment. [0030] The conducting powder may consist of titanium and/or titanium alloys and/or titanium hydrides. If titanium hydrides are used, a step for transforming the hydrides to metal is introduced. [0031] The conducting powder may also be powders of metals like nickel, molybdenum, tungsten, cobalt, niobium, zirconium and their alloys. [0032] Mixtures of metal powders or metal alloy powders or metal compounds can be used. [0033] The deposition of the conductive powder can be done by printing using various techniques known in the art, such as slot die coating, gravure, spraying, screen printing, knife coating, blade coating, doctor blading, flexo printing, and dip coating. Dry powder deposition can also be used. [0034] The conducting powder can be deposited onto various substrates or DSC components, like plastics, PET, PEN, TCO-less glass, TCO-covered glass, glass, metal, or porous substrates such as glass microfiber-based substrates, ceramic microfiber based-substrates, cellulose-based substrates, textile, ceramic paper or onto a TiO 2 layer or separator layer of the DSC. [0035] For the porous substrates it is possible to form a PCPL on one side of the substrate and a PCPL or other DSC components on the other side of the substrate. [0036] The PCPL can have different functions in the DSC: Back contact function. A back contact extracts electrons from the working electrode. Counter electrode function. The counter electrode transfers electrons to the electrolyte. Back contact and counter electrode. [0040] A DSC can also be a hole conductor having the current in the reverse direction. [0041] When a PCPL is used as a back contact, the PCPL is in electrical contact with the working electrode. [0042] When a PCPL is used as a counter electrode, the PCPL is part of the counter electrode opposite to the working electrode. [0043] Advantages of a PCPL in DCSs: Printing is much faster than vacuum deposition techniques, such as sputtering deposition or electron beam evaporation deposition, in terms of produced deposited area and produced deposited amount per area per time unit. Printing can be done selectively so there is no need for expensive masking, because the layers can be printed in patterns. Printing results in less waste material compared to vacuum deposition. Printing can be made on a variety of substrate. Printing equipment is cheaper compared to vacuum deposition equipment. Highly porous PCPL films can be formed allowing for fast electrolyte ion transport and fast dye-sensitization. Thicker films can be formed without electrolyte ion transport or dye-sensitization problems. Highly conductive porous PCPL films can be formed allowing for the printing of wider solar cell segments. [0052] Printing technique can also be used for forming current collectors. A current collector collects electrons from the back contact and/or the counter electrode. The conductive powder layer of the current collector shall not be porous. DETAILED DESCRIPTION OF THE INVENTION [0053] The present invention will be further explained with reference to the following description of exemplary embodiments and accompanying drawings. [0054] The reference to dyed TiO 2 as working electrode is not limited to TiO 2 , but could be any other material or materials suitable as dyed working electrode in a DSC, such as ZnO. Likewise, the electrolyte can consist of any suitable electrolyte for a DSC or solid state hole conductors. [0055] The porous conducting powder may be powders of metals like titanium or molybdenum, tungsten, cobalt or nickel, niobium, zirconium and their alloys. Mixtures of these metal powders or metal alloy powders can be used. [0056] It is possible to mix in particles of conducting metal oxides to the metal particles. Particles consisting of carbides and nitrides of metals can also be mixed in. It is also possible to mix in ceramic binders such as silica nano-particles, inorganic precursors such as titanium chelates, titanates. Titanium acetyl acetonate might be used as well. Also silanes can be used. [0057] Titanium and its alloys have high corrosion resistance capable of withstanding corrosive attack by the electrolyte. STM (grade 1-38) defines a number of titanium standards that can be used. ASTM grades (1-4), i.e., commercially pure (CP) titanium is for example useful in applications where extremely high corrosion resistance is required. [0058] The conducting particles can have a size or diameter of around 0.1 μm and up to 15 μm, or up to 10 μm. The thickness of the PCPL can be 0.3-100 microns. [0059] FIG. 1 shows a cross-section of a sandwich type DSC. A dyed TiO 2 working electrode layer 1 is positioned on top of a substrate 2 . A PCPL 3 is positioned on top of the dyed TiO 2 working electrode layer 1 . A counter electrode 4 having a platinized TCO layer 5 and a glass or plastic substrate 6 is positioned opposite to the working electrode 1 . The electrolyte 7 is in contact with both the counter electrode and the working electrode. The electrolyte is in physical contact with the PCPL and the dyed TiO 2 layer, and it penetrates both the PCPL and the dyed TiO 2 layer. [0060] In FIG. 1 , the PCPL 3 works as a back contact to the dyed TiO 2 working electrode layer 1 . This means that a TCO back contact layer used in conventional DSC can be omitted and be replaced by a PCPL. The porosity of the PCPL 3 allows for the electrolyte 7 to penetrate and pass through the PCPL. Photo-generated charges created in the dyed TiO 2 can be extracted by the PCPL. [0061] Another variation is for the TCO layer 5 of the counter electrode 4 to be omitted and replaced by a PCPL. Such a PCPL could contain platinum to achieve the catalytic effect. Consequently, a counter electrode 4 having platinized PCPL could replace a platinized TCO layer on glass or plastic in terms of both electrical conductivity and catalytic effect. [0062] The PCPL in the DSC can serve the function as an electron conductor in the counter electrode and/or an electron conductor and a catalytic layer in the counter electrode. This also means that the TCO layer on the counter electrode can be replaced by a PCPL. [0063] The substrate 2 on dyed TiO 2 working electrode layer 1 can be glass. It is important that the substrate 2 for the dyed TiO 2 working electrode layer 1 in FIG. 1 is transparent in order to allow for incident light to be absorbed by the dyed TiO 2 The substrate 2 should have good temperature resistance in order to withstand processing at high temperatures. [0064] FIG. 2 shows a cross-section of a sandwich type DSC. A PCPL 3 has been deposited on top of a substrate 2 ; a working electrode layer 1 is deposited on top of the PCPL 3 . A counter electrode 4 having a platinized TCO layer 5 and a glass or plastic substrate 6 is positioned opposite to the working electrode layer 1 . The electrolyte 7 is in contact with both the counter electrode 4 and the working electrode 1 . The electrolyte 7 is also in physical contact with the PCPL 3 and the dyed TiO 2 working electrode layer 1 , and the electrolyte 7 penetrates both the PCPL 3 and the dyed TiO 2 working electrode layer 1 . [0065] In FIG. 2 , the PCPL 3 works as a back contact to the working electrode 1 . This means that a TCO back contact layer used in conventional DSC can be omitted and be replaced by a PCPL. FIG. 3 shows a cross-section of a monolithic type DSC. A dyed TiO 2 working electrode layer 1 is positioned on top of a substrate 2 . A PCPL 3 is positioned on top of working electrode layer 1 . A porous separator 8 is deposited on top of the PCPL 3 . A porous counter electrode 9 is deposited on top of the separator 8 . The electrolyte (not shown in FIG. 3 ) is in contact with the counter electrode 9 and the separator 8 and the PCPL 3 and the dyed TiO 2 working electrode layer 1 . The electrolyte penetrates the porous counter electrode 9 and the separator 8 and the PCPL 3 and the dyed TiO 2 working electrode layer 1 . [0066] In FIG. 3 , the PCPL 3 works as a back contact to the working electrode 1 . This means that a TCO back contact layer used in conventional DSC can be omitted and be replaced by a PCPL. The porosity of the PCPL allows for electrolyte to penetrate the PCPL and pass through the PCPL. The photo-generated charges created in the dyed TiO 2 can be extracted by the PCPL. Since the PCPL is electrically conductive, the need for a TCO layer for charge extraction is reduced. [0067] A variation to FIG. 3 could be that the porous counter electrode is made as a PCPL. Such PCPL could comprise platinum in order to increase the catalytic effect. [0068] The substrate 2 on dyed TiO 2 working electrode layer 1 can be glass. It is important that the substrate 2 for the dyed TiO 2 working electrode layer 1 in FIG. 1 is transparent in order to allow for incident light to be absorbed by the dyed TiO 2 The substrate 2 should have good temperature resistance in order to withstand processing at high temperatures. [0069] The separator 8 is a porous and chemically inert and poorly electrically conductive oxide, such as alumina, aluminosilicate, magnesia, silica, and zirconia. The separator material should also be substantially inert to the electrolyte and the dye sensitization processes. The separator layer 8 should bond well to the PCPL 3 and provide adequate electrical insulation as well as good porosity and electrolyte permeation at minimal ohmic drop in the electrolyte. It is possible to form a separator layer by multiple depositions of chemically inert and poorly conducting layers of the same or different materials. It is also possible to form a separator layer by the deposition of alternating layers of chemically inert and poorly electrically conductive layers. [0070] The porous counter electrode 9 comprises conventional carbon-based materials such as graphite, carbon black, and platinum particles. Carbon nano-tubes or -cones can also be used in such mixtures. [0071] The porous counter electrode 9 normally comprises a catalytic layer and a conducting layer. The catalytic layer is adapted to accommodate the iodine redox reaction in the cell. In direct contact with the catalytic carbon layer is a conductive carbon layer. [0072] FIG. 4 shows a cross-section of a monolithic type DSC. A porous counter electrode 9 is deposited on top of a substrate 2 , a separator 8 is deposited on top of the porous counter electrode 9 , a PCPL 3 is formed on top of the separator 8 , and a dyed TiO 2 working electrode layer 1 is deposited on top of the PCPL 3 . The electrolyte (not shown in FIG. 4 ) is in contact with the counter electrode 9 , the separator 8 , the PCPL 3 , and the working electrode 1 . In FIG. 4 , the PCPL 3 works as a back contact to the working electrode 1 . This means that a TCO back contact layer used in conventional DSC can be omitted and be replaced by a PCPL. A variation to FIG. 4 could be that the porous counter electrode is replaced with a PCPL. Such a PCPL could contain platinum particles in order to increase its catalytic effect. [0073] The substrate 2 on the porous counter electrode 9 can be a glass substrate or a metal foil substrate. [0074] In order to produce the DCS shown in FIGS. 1 to 4 the cells are sealed and additionally, electrical connections are made so that the photo-generated current can be used in an external electrical circuit. [0075] A conductive powder layer, CPL, can be used as a current collector. Parallel and/or series cell interconnections consisting of CPL can be printed selectively without using masks. [0076] FIG. 5 shows a solar cell device based on the cell shown in FIG. 1 . [0077] FIG. 5 shows how the cell geometry in FIG. 3 can be implemented in a solar cell device. A sealing compound 10 a, b is deposited around all the edges of the cell to encapsulate the DSC components in order to prevent mass transfer between the cell and the surrounding environment. It can be seen that the PCPL 3 is formed on top of the working electrode 1 and on the substrate 2 next to one side of the working electrode 1 in such a way that the photocurrent from the dyed TiO 2 is conducted down and away from the dyed TiO 2 to a CPL 11 . The CPL 11 is formed on top the outer end of the PCPL 3 . A layer of conducting silver or other conductive material capable of current transport 12 a is deposited on top of the CPL. Conducting silver 12 b is also deposited on top of the TCO layer on the counter electrode. [0078] The second CPL forms an electrical junction between the conducting silver and the PCPL. In order to achieve as secure seal as possible across this junction, and to minimize the possibility of contamination of both the DSC components and the environment surrounding the cell, the CPL should have an adequate thickness and a very low porosity. [0079] The current can be collected in an external circuit (not shown in the figure) via the conducting silver 12 a, b. [0080] FIG. 6 shows a solar cell based on FIG. 2 . [0081] FIG. 6 shows how the cell geometry in FIG. 2 can be implemented in a device. A sealing compound 10 a, b is deposited around all the edges of the cell to encapsulate the DSC components. It can be seen that the PCPL 3 is formed below of the working electrode 1 and next to one side of the working electrode in such a way that the photocurrent from the dyed TiO 2 is conducted away from the dyed TiO 2 to a CPL 11 . A thicker CPL 11 is deposited on top the outer end of the PCPL 3 . A layer of conducting silver 12 a is deposited on top of the CPL 11 . Conducting silver 12 b is also deposited on top of the TCO layer 5 of the counter electrode 4 . [0082] The CPL 11 forms an electrical junction between the conducting silver 12 a and the PCPL. The CPL 11 preferably has as low porosity as possible. [0083] The generated current can be collected in an external circuit (not shown in the figure) via the conducting silver. [0084] FIG. 7 shows how the cell geometry in FIG. 3 can be implemented in a device. A sealing compound 10 a, b, c is deposited around all the edges of the cell to encapsulate the DSC components. It can be seen that the PCPL 3 is formed on top of the working electrode 1 and on the substrate 2 next to one side of the working electrode 1 in such a way that the photocurrent from the dyed TiO 2 working electrode is conducted down and away from the dyed TiO 2 to a CPL 11 a. The CPL 11 a is deposited on top of the outer end of the PCPL 3 . A layer of conducting silver 11 a is deposited on top of the CPL 11 . A separator 8 is deposited on top of and next to the PCPL 3 . A porous counter electrode 9 is deposited on top of and next to the separator 8 . A second CPL 11 b is deposited connecting the porous counter electrode 9 with the conducting silver 12 b. [0085] CPL 11 a, b form an electrical junction between the conducting silver and the PCPL. [0086] The generated current can be collected in an external circuit (not shown in the figure) via the conducting silver. [0087] FIG. 8 shows how the cell geometry in FIG. 4 can be implemented in a device. A sealing compound 10 a, b, c is deposited around all the edges of the cell to encapsulate the DSC components. It can be seen that the PCPL is formed on top of the working electrode 1 and on the substrate 2 next to one side of the working electrode 1 in such a way that the photocurrent from the dyed TiO 2 is conducted down and away from the dyed TiO 2 to a CPL 11 a. The CPL 11 a is deposited on top of the outer end of the PCPL 3 . A layer of conducting silver 12 a is deposited on top of the CPL 11 a. The separator 8 is deposited on top of and next to one side of a porous counter electrode 9 on the substrate 2 . A CPL 12 b is deposited on top of the porous counter electrode 9 . [0088] The CPL 11 a forms an electrical junction between the conducting silver 12 a and the PCPL 3 . The CPL 11 b forms an electrical junction between the conducting silver 12 b and the porous counter electrode 9 . [0089] The generated current can be collected in an external circuit (not shown in FIG. 8 ) via the conducting silver. [0090] For the porous substrates, it is possible to deposit DSC components on both sides of the substrate. For example, it possible to form a PCPL on one side of a porous glass microfiber-based substrate and a TiO 2 working electrode on the other side of the glass microfiber-based substrate. The porosity of the glass microfiber-based substrate allows for mechanical contact and electronic contact between the PCPL and the dyed TiO 2 working electrode layer. Thus, the PCPL will function as a back contact to the dyed TiO 2 layer. Consequently, the glass microfiber-based substrate will serve as a porous substrate matrix for formation of the PCPL and TiO 2 working electrode, and it will also serve the purpose of reinforcing the mechanical stability of the PCPL and TiO 2 working electrode layers. By depositing a separator layer on top of the PCPL and by depositing a porous counter electrode on top of the separator layer and by filling the porous structure with an electrolyte, a basic DSC device is formed. [0091] Alternatively, it is possible to form the PCPL on one side of a porous glass microfiber-based substrate, and a separator layer on the other side of the glass microfiber-based substrate. A porous counter electrode layer could then be deposited on top of the separator layer. Consequently, such geometry could be used as a back contact and counter electrode. By depositing a TiO 2 layer on top of the PCPL and by filling the porous structure with an electrolyte, a basic DSC is formed. The porous counter electrode could consist of conventional carbon-based materials or a PCPL with adequate catalytic properties. [0092] Alternatively, it is possible to form the PCPL on one side of a porous glass microfiber-based substrate, and to deposit TiO 2 on the other side of the glass microfiber-based substrate. [0093] The above examples are in no way exhaustive. [0094] The DSC cells manufactured on porous substrates must be sealed in order to ensure the integrity of the DSC components. Sealing can be made for example by placing the porous substrate including all deposited DSC components between two sheets of glass and by sealing the edges of the two glass sheets. Additionally, electrical connections have to be made such that the generated current can be used in an external electrical circuit. [0095] The manufacturing of the PCPL layer comprises 6 steps: Powder preparation Powder ink preparation Powder ink deposition Powder layer heating Powder layer compaction Powder layer after treatment Powder Preparation [0102] A starting powder of a suitable composition can have particle sizes ranges from 0.1 to 10 micrometer. It is preferred that the maximum particle size is kept below 10 μm or below 1 μm. An amount below 50% by weight of the total particle content could be particles with diameters below 0.1 μm. Mixtures of particles with different particle sizes can be used. [0103] The particles may be spherical and/or irregular-shaped. [0104] Metal oxide on the metal particle surface prevents good metallic inter-particle contact. Removal of the oxide layer on the metal particles can be made by pre-treating the metal particles through heating in an inert atmosphere, vacuum, or reducing atmosphere. If mixtures of titanium and titanium hydrides are used, then the titanium hydride can serve as a hydrogen source during the heating procedure. The oxide layer on the titanium particles can also be removed by chemical methods, such as chemical milling and pickling using standard chemical agents. The cleaning chemicals used in standard welding practice can be used as well. [0105] It is possible to mix in catalytic amounts of platinum with the titanium powder for forming counter electrodes in the DSC. The metal powder can also be treated separately with platinum salts to achieve a deposition of platinum on the surface of the metal particles. It is possible to mix in particles of conductive metal oxides to the metal particles, such as ITO, ATO, PTO, FTO. Particles consisting of conductive metal carbides and metal nitrides can also be mixed with the metal powder. Powder Ink Preparation [0106] Water can be used as a solvent for the ink. Organic solvents, such as terpenes, alcohols, glycolethers, glycol ether acetates, ketones, hydrocarbons, and aromatic solvents, may also be used. Chlorinated solvents, however, should be avoided. [0107] Binders, or other such substances, can be used to enhance the mechanical strength of the deposited conductive powder layer before heating the layer. Ink Deposition [0108] The conductive powder ink can be deposited by conventional printing techniques. Examples of printing techniques are; slot die coating, gravure, spraying, screen printing, knife coating, blade coating, doctor blading, or dip coating. [0109] Screen printing is preferable for powder deposition for manufacturing DSC because deposition can be made selectively, and a few micrometers up to tens of micrometer thick layers can easily be deposited on a wide variety of substrates such as rigid, flexible, or porous substrates. Dip coating is advantageous in cases where both sides of the substrate are to be covered simultaneously, thus reducing the number of process steps. Slot die coating can be used for roll-to-roll production of flexible substrates. [0110] The conductive powder ink can be deposited onto various substrates like plastics, PET, PEN, TCO-less glass, TCO-covered glass, glass, metal, or porous substrates such as glass microfiber-based substrates, ceramic microfiber-based substrates, metal mesh, porous metal, cellulose-based substrates, textile, or onto the TiO 2 layer or separator layer of the DSC. Conductive Powder Layer Heating [0111] After the conductive powder ink has been deposited, the solvent is removed by heating in air or an inert atmosphere to create a dry powder layer. [0112] Non-volatile organic substances can be removed by oxidation or reduction by heating, in an oxidizing or reducing atmosphere, respectively. [0113] It is possible to remove non-volatile inorganic substances such as inorganic pore formers like ammonium carbonate, in the dry conductive powder layer. Non-volatile inorganic substances such as ammonium carbonate can be removed by decomposition at elevated temperatures in air, nitrogen, or vacuum. Conductive Powder Layer Compaction [0114] Compaction of the dry conductive powder layer is desired in order to form a PCPL. The PCPL shall have sufficient mechanical strength to withstand handling of the DSC. A contact between the powder particles in order to achieve electrical conductivity while maintaining sufficient porosity to allowing the electrolyte to circulate should be achieved. The strength of the compressed PCPL depends on the mechanical interpenetration of powder particle irregularities favored by plastic deformation. The use of only spheroidical metal particles in the PCPL results in less interpenetration of neighboring particles and lower mechanical strength. The use of irregular-shaped metal particles in the PCPL results in more interpenetration of neighboring particles and higher mechanical strength. High compaction force results in lower PCPL porosity and lower PCPL permeability; the higher the compaction pressure, the more compact and mechanically stable the PCPL becomes. A pressure range within 10-2000 kg/cm 2 or within the range of 10-200 kg/cm 2 is normally required in order to achieve a density of around 40%-70%. [0115] Several compaction methods are available, including isostatic compaction, die compaction, and roll compaction. Roll compaction is, for example, economical and results in a uniform PCPL density with tight dimensional tolerances. Heat can be applied to the compaction tool during compaction. Also ultrasonic vibration can be applied to the compaction tool during compaction. [0116] Using pressure plates to form the PCPL can be advantageous for brittle substrates. [0117] It is possible to use compaction tools with micro-structured surfaces in order to transfer the surface microstructure surface to the powder layer during compaction. The surface microstructure of the compaction tool could have e.g. pyramidal-shape, sinusoidal-shape, or zig-zag-shape. Rendering a surface microstructure to the PCPL layer could be useful in order to achieve optical effects, such as enhanced light absorption in the DSC. Alternatively, this type of treatment can be performed in the PCPL after treatment, see below. [0118] In order to avoid that the PCPL layer sticks to the press tools, release materials can be used. [0119] If the PCPL layer is deposited onto a flat non-sticking substrate such as molybdenum or yttrium oxide, the PCPL can be removed from the substrate to create a free-standing PCPL. PCPL After Treatment [0120] Any organic substances remaining in the compacted PCPL can be removed by heating. [0121] Non-volatile inorganic substances, such as inorganic pore formers like ammonium carbonate, remaining in the dry PCPL, can be removed by decomposition at elevated temperatures in air, nitrogen, or vacuum. [0122] In the event that titanium hydride is used, it may serve as the hydrogen source. [0123] In order to improve the metallic particle-to-particle contact, the compacted PCPL can be subjected to sintering by applying heat. Sintering causes diffusion across the metallic particle grain boundaries to achieve higher mechanical strength; specifically, mechanical strength and corrosion resistance properties are dependent on the interaction with the sintering atmosphere. [0124] Porous materials are commonly sintered in inert atmospheres such as argon or vacuum, or they can be sintered in reducing atmospheres such as hydrogen-argon mixtures, nitrogen-hydrogen mixtures, or hydrogen and dissociated ammonia. In the event that titanium hydride is used, it serves as the hydrogen source. Titanium is highly reactive and requires good vacuum sintering, or sintering in dry argon with a high purity, inert backfill gas. [0125] It is also possible to apply post-etching in order to increase the porosity of the PCPL layer. [0126] It is possible to perform several different consecutive after treatment steps: e.g., first removing any remaining non-volatile organic substances in the PCPL by heating the PCPL in an oxidative atmosphere such as air, and then applying heat to sinter the PCPL. [0127] It is possible to apply further compaction to reduce variations in thickness, in order to achieve a more well-defined thickness of the PCPL. [0128] It is possible to apply compaction using microstructure tools to achieve a micro-structured surface on the PCPL. [0129] The porosity of the PCPL can vary between 15% and 85%. A porosity between 40% and 70%, or between 50% and 60%, is preferred. [0130] The thickness of the PCPL can be in the range of 1-100 microns. EXAMPLE 1 [0131] A PCPL in a DSC was formed by screen printing a conductive powder ink containing terpineol and titanium metal powder onto a porous glass-fiber substrate. The deposited conductive powder layer was dried at 120° C. in air for 3 minutes. The deposited layer was then compacted to yield a porosity of 55%. The thickness of the roll compacted PCPL was 32 μm. Subsequently, the PCPL was subjected to sintering by flash heating in an inert atmosphere (argon). The sheet resistance of the PCPL was less than 1 ohm per sq. EXAMPLE 2 [0132] A PCPL in a DSC was formed by depositing a conductive powder ink containing water and titanium metal powder onto a porous ceramic Al 2 O 3 fiber substrate. The deposited conductive powder layer was dried at 120° C. in air for 10 minutes. The deposited conductive powder layer was thereafter compacted to yield a porosity of 46%. The thickness of the roll compacted PCPL was 24 μm. Subsequently, the PCPL was subjected to flash heating in an inert atmosphere (argon). The sheet resistance of the PCPL was less than 1 ohm per square. EXAMPLE 3 [0133] A PCPL in a DSC was formed by depositing a conductive powder ink containing hydrocarbon solvent and titanium metal powder onto a porous glass-fiber substrate. The deposited conductive powder layer was dried at 120° C. in air for 3 minutes. The deposited layer was then compacted to yield a porosity of 51%. Subsequently, the PCPL was subjected to sintering by flash heating in an inert atmosphere (argon) using a Sinteron 2000. The sheet resistance of the film was less than 1 ohms per square. [0134] Next, a conductive powder was deposited on the opposite side of the glass-fiber substrate. The second deposition was performed using a conductive powder ink containing hydrocarbon solvent and titanium metal powder. The titanium metal powder contained small platinum metal particles deposited onto the surface of the titanium metal particles. The second conductive powder layer was dried at 120° C. in air for 3 minutes. The layer was then compacted to yield a porosity of 49%. Subsequently, the second compacted PCPL was subjected to flash heating in an inert atmosphere (argon) using a Sinteron 2000. The sheet resistance of the film was less than 1 ohms per square. EXAMPLE 4 [0135] A PCPL in a DSC was formed by depositing a conductive powder ink containing terpineol and titanium metal powder onto a porous glass-fiber substrate. The deposited conductive powder layer was dried at 120° C. in air for 3 minutes. The deposited layer film was then compacted to yield a porosity of 62%. The thickness of the PCPL was 21 μm. Subsequently, the PCPL was subjected to flash heating in an inert atmosphere (argon). The sheet resistance of the film was less than 1 ohm per square. [0136] Next, a second conductive powder was deposited on top of the first PCPL. The second deposition was performed using an ink containing isopropanol and titanium metal powder. The conductive powder layer was dried at 120° C. in air for 3 minutes. The layer was then compacted. Subsequently, the second PCPL was subjected to flash heating in an inert atmosphere (argon) using a Sinteron 2000. The sheet resistance of the double layer PCPL was less than 1 ohm per square. EXAMPLE 5 [0137] A PCPL in a DSC was formed by screen printing a conductive powder ink containing terpineol and titanium hydride powder onto a porous glass-fiber substrate. The deposited conductive powder layer was dried at 120° C. in air for 3 minutes. The deposited layer was then compacted to yield a porosity of 57%. The thickness of the compacted PCPL was 20 μm. Subsequently, the PCPL was subjected to flash heating in an inert atmosphere (vacuum). The sheet resistance of the PCPL was less than 1 ohms per square. EXAMPLE 6 [0138] A PCPL in a DSC was formed by screen printing a conductive powder ink containing terpineol and titanium hydride powder onto a molybdenum sheet. The deposited conductive powder layer was dried at 120° C. in air for 3 minutes. The deposited layer was then compacted to yield a porosity of 50%. The thickness of the compacted PCPL was 20 μm. Subsequently, the PCPL was subjected to sintering by flash heating in vacuum. The PCPL layer could be removed from the molybdenum sheet in the form of a free-standing film. The sheet resistance of the PCPL was less than 1 ohms per square.	A method for producing a Dye-Sensitized Solar cell (DSC) comprising a substrate, a working electrode, a back contact for extracting photo-generated electrons, an electrolyte, and a counter electrode where the back contact and/or the counter electrode is formed by a porous conductive powder layer, PCPL. The PCPL is prepared by the following steps: a. powder preparation; b. powder ink preparation; c. powder ink deposition; d. powder layer heating; e. powder layer compaction; and f. powder layer after treatment.	8
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an antimicrobial composition for use as an emollient alcohol based skin disinfectant that will not irritate or dry the skin. The skin disinfecting formulations of the present invention are particularly useful in the healthcare profession as a hand healthcare preparation or as a pre-surgical scrub without requiring a secondary emollient application. [0003] 2. Description of Relevant Art [0004] Hand washing by healthcare professionals is an essential component of infection control activities. Healthcare professionals attending to patient care wash their hands to control the spread of infection from patient to patient and surgical procedures are routinely proceeded by surgical hand scrubbing and patient pre-operative skin preparation. [0005] Hand washing procedures are performed in several ways. Several procedures include an ordinary antimicrobial bar soap, a skin disinfecting alcohol based preoperative preparation agent, or rubbing alcohol. The repeated use of these procedures causes the hands to become rough, dry and cracked. [0006] The majority of the commercially available scrubs include detergents and an antimicrobial agent or a preservative. Examples of the antimicrobial or preservative agents include iodine formulations, iodophors, phenolic compounds such as parachlorometaxylenol and hexachlorophene and bis-biguanides such as chlorhexidine gluconate (CHG). [0007] Although alcohol in general is recognized for its very effective disinfecting properties, it is not used directly with skin or in scrub formulations because it is a defatting agent. When alcohol is applied to the human skin, it makes it very dry, often developing chapped and cracked skin. Furthermore, it is difficult to formulate a detergent solution with alcohol that will lather like ordinary soaps and detergents when used with water. However, due to the disinfecting properties of alcohol, it is desirable to produce a skin disinfecting formulation with alcohol which is mild and gentle to the skin, and is effective at controlling microorganism populations on the skin. SUMMARY OF THE INVENTION [0008] The present invention is a skin disinfecting formulation that provides antimicrobial effectiveness and is mild and gentle to human skin. The skin disinfecting formulation desirably comprises an alcohol, a thickening agent, a preservative, an emulsifier, a moisturizer and/or emollient and water. [0009] Preferably, the skin disinfecting formulation may further comprise a colorant or a fragrance. Most preferably, the skin disinfecting formulations comprise by weight: [0010] (a) from about 60% to about 95% of an alcohol; [0011] (b) from about 0% to about 3% of a thickening agent; [0012] (c) from about 1% to about 5% of an emulsifier; [0013] (c) from about 0% to about 5% of a preservative/antimicrobial agent; [0014] (d) from about 0.05% to about 5% of a fragrance; [0015] (e) from about 0.05% to about 1% of a colorant; and [0016] (j) from about 6% to about 30% of water. [0017] The skin disinfecting formulations of the present invention are useful in providing substantial antimicrobial effectiveness and surprisingly, provide substantial non-irritancy to the skin in view of the alcohol component of the formulations. [0018] Another attribute of the skin disinfecting formulation is its ability to not dry the skin. [0019] Another advantage of the skin disinfecting formulation is the compatibility with other Chlorohexidine Gluconate products, which enhances the antimicrobial activity of both formulations by further reducing the microbial flora on the substrate. [0020] A further advantage of the skin disinfecting formulations of the present invention is the potential to provide long-term residual activity on the applicant's skin to prevent bacteria growth back to the base line of normal skin flora population. [0021] The skin disinfecting formulations of the present invention will disinfect the skin while also providing emolliency to the skin. Further, the skin disinfecting formulations of the present invention can also be used as a general purpose hand wash to decontaminate the hands of healthcare professionals before examining any patient. [0022] Healthcare professionals perform a routine hand scrubbing procedure many times a day. The typical and/or commonly used scrub solutions contain chemical compounds such as iodine, chlorhexidine gluconate (CHG), PCMX and hexachlorophene. All of these chemical compounds disinfect the skin as well as bind to the skin, thus providing persistent activity. Healthcare professionals may also use the skin disinfecting formulation of the present invention throughout the day. Since health care professionals scrub and wash their hands many times a day, the chemical compounds may buildup on their skin and accumulate through out the day. The intended use of the present invention includes rinsing off the hands and forearms with water to remove any residual chemical build up. Therefore the skin disinfecting formulation of the present invention would be ideal for both routine use throughout the day and as a final wash before leaving the work place. [0023] Surprisingly, the formulations of the present invention provide substantially effective skin disinfecting properties with the use of alcohol in the formulations as well as being mild and gentle to the skin, and substantially effective against microorganisms. Antimicrobial formulations of the present invention are typically packaged in a container. Typically, a foot pump is used to create an increased pressure inside the closed container. The positive pressure difference across the container wall results in the solution being forced up a solution delivery straw. Such a formula must therefore satisfy certain physical requirements, which include: viscosity in the range of 100-2500 cps; alcohol as an active ingredient in the range of 60-95% w/w; and antimicrobial agents in a preservative range of 0.001-5.0% w/w. In addition, the formulation must be efficacious and non-irritating when used. With these parameters in mind the present invention provides an alcohol scrub with greater than 60% alcohol that is effective against microorganisms and causes rapid bacterial reduction. DETAILED DESCRIPTION [0024] The present invention may be embodied in other specific forms and is not limited to any specific embodiments described in detail which are merely exemplary. Various other modifications will be apparent to and readily made by those skilled in the art without departing from the scope and spirit of the invention. The scope of the invention will be measured by the appended claims and their equivalents. [0025] The skin disinfecting formulation of the present invention comprises an alcohol, a thickening agent, an emulsifier, a preservative, a moisturizer and/or emollient and water. The skin disinfecting formulations may further comprise a fragrance and/or a colorant. [0026] An alcohol is preferably used in the skin disinfecting formulations because of the inherent bactericidal properties. Generally, a concentration of alcohol over 60% is an effective germicidal agent. It kills gram-positive, gram-negative bacteria, fungi, mold and a variety of viruses. The potent activity of alcohol against micro-organisms is due to its denaturation of proteins and enzymes and cellular dehydration. Typically, the more concentrated the alcohol solution the more potent the antimicrobial effect. However, increasing the alcohol concentration has the deleterious effect of increasing the level of skin irritancy on healthcare workers using the solution. Surprisingly, the present invention describes a formulation with an alcohol concentration of 70% without an increase in skin irritancy. [0027] An alcohol for use in the skin disinfecting formulation includes, but is not limited to, isopropyl alcohol, ethanol and n-propyl alcohol. [0028] The preferred alcohol for use in the skin disinfecting formulations is isopropanol and ethanol. Preferably, ethyl alcohol may be present in the skin disinfecting formulation in an amount from about 60 to about 95 weight percent, and most preferably at about 70 weight percent. [0029] Thickening agents are used in the skin disinfecting formulations to adjust the viscosity and stability of the formulations. Generally, due to the use of alcohol as a solvent, the typical thickening agent of the present invention remains soluble in alcohol concentrations up to at least 70%. The thickening agents used in the present invention are cationic polymers. Typical cationic thickening agents include cellulosic materials such as starch, methocel (methyl cellulose ethers) and hydroxycellulose. [0030] It is believed that hydrophobic thickeners provide cellulose compositions that improve the biocidal activity of the composition due to the minimum amount of water absorbed from the composition during the thickening process. Thickeners that are less hydrophobic may cause the skin disinfecting formulations to be turbid or milky because the skin disinfecting formulations may precipitate if there is not sufficient water in the composition. [0031] A suitable thickening agent, for skin disinfecting formulations is hydroxypropyl methylcellulose, METHOCEL® (a trademark of the Dow Chemical Company, Midland, Mich.) sold by The Dow Chemical Company. METHOCEL® thickener is 91% hydroxypropyl methyl cellulose which dissolves in aqueous alcohol solution, is nonionic, and is a highly efficient water retention agent. [0032] Preferably, the thickening agent may be present in the skin disinfecting formulations in an amount from about 0 to about 3 weight percent and most preferably at about 1 weight percent. [0033] An emulsifier is typically used in the skin disinfecting formulations to disperse oily emollients in water solution. More importantly, an emulsifier is a solubilizer. [0034] A suitable cationic emulsifier for the skin disinfecting formulation is Incroquat Behenyl® (Trademark of Croda, Inc., Parsippany, N.J.) sold by Croda, Inc. Incroquat Behenyl® is a compound of 25% active solution of behenyl trimonium methosulfate in cetearyl alcohol and is available in flaked/pastel form. This cationic polymer is a very active conditioning agent and bonds to skin through the native negative charge on the skin. [0035] A second suitable emulsifier available from Croda, Inc. is Incroquat CR Concentrate, which consists of cetearyl alcohol, PEG-40 Castor Oil, and stearalkonium chloride. The Incroquat CR Concentrate is one part formulating aid and one part conditioner and self emulsifier. Incroquat CR concentrate will produce a creamy feel, while rinsing and conditioning efficiently. [0036] A combination of these two cationic emulsifers is preferred. The combination provides a smooth after feel and neutralizes the static charge of the skin especially when used in conjunction with isopropyl palmitate, or Incroquat B65C® or Incroquat CT30®, all available from Croda, Inc. [0037] Alcohol is an excellent antimicrobial agent and will preserve the skin disinfecting formulation very well. However, when the formulation is applied to the skin, the alcohol will evaporate after a period of time. Thus, a small amount of a non-volatile organic antimicrobial agent may be added to the skin disinfecting formulation to preserve the antimicrobial effect of the formulation for an extended period of time. [0038] The preservative is selected so as not to upset desirable physical and chemical properties of human skin. A properly selected preservative maintains stability under use and storage conditions (pH, temperature, light, etc.), for a required length of time. It will also prevent the growth of microbes and/or is effective in killing microbes to achieve a continuing antimicrobial effect. [0039] A suitable preservative may be selected from the class of phenolics such as parachlorometaxylenol, or bis-biguanides such as CHG, chlorhexidine diacetate or Quaterium class such as Benzethonium chloride, benzalkonium chloride. Hexetidine, Germaben II®, Kathon CG®, Triclosan are other antimicrobial agents that may also be suitable as preservatives. Benzethonium chloride and benzalkonium chloride as Hyamine 3500 a trademark of Lonza, Inc., (Fair Lawn, N.J.) available from Lonza, Inc., CHG is available from Xttrium laboratories, (Chicago, Ill.) and Germaben II is available from Sutton Laboratories, (Chatham, N.J.). Two other preservatives popular in the cosmetics industry are methylparaben and propylparaben. These chemicals are available from Mallinckrodt Chemical Company (St. Louis, Mo.). [0040] Preferably, the preservative may be present in the skin disinfecting formulations in an amount from about 0 to about 5 weight percent and most preferably at about 0.5 weight percent. In an even more preferred embodiment combinations of two or more preservative compounds are present in the formulation. [0041] Emollients in their physical form are thin liquids, oils of various viscosities, fatty solids or waxes. Hydrocarbons function essentially as emollients by virtue of their ability to lubricate and/or hold water at the skin surface due to their relative occlusivity. Mineral oil is such a fluid. Some emollients are hydrophilic (glycerin, propylene glycol) and are water soluble lubricants and humectants. Since emollients may be fatty chemicals, oily or waxy in nature, they can impart barrier properties to formulations and are then referred to as moisturizers. [0042] Moisturizers are substances which provide external lubricant behavior, such as to soften and soothe the skin because they encourage skin water retention. [0043] The function of the moisturizer and/or emollient in the skin disinfecting formulation is to provide relief for dry and sensitive skin. Therefore, chapping of the skin may be prevented. In addition, the moisturizer and/or emollient does not leave a tacky after feel on the skin. [0044] Suitable moisturizers and/or emollients in the skin disinfecting formulations include isopropyl palmitate, lanolin, derivatives of lanolin such as the ethoxylated acetylated alcohol and surface active alcohol derivatives of lanolin, propylene glycol, polypropylene glycol, polyethylene glycol, mineral oils, squalane, fatty alcohols, glycerin, and silicons such as dimethicone, cyclomethicone, simethicone. Preferred moisturizers and/or emollients are selected from lanolin derivatives, polyols and cetylethers. Most preferably, the moisturizer and/or emollient in the skin disinfecting formulations is a combination of mineral oil, dimethicone, glycerine, isopropyl palmitate. [0045] Preferably, moisturizers and/or emollients are present in the skin disinfecting formulations in an amount from about 0.05 to about 5 weight percent and most preferably at about 1.0 weight percent. [0046] Other ingredients which are conventional or desirable for aesthetic purposes may also be added to the skin disinfecting formulations as long as they do not adversely affect the overall properties of the formulation. Such ingredients may include a perfume or fragrance to provide a pleasing scent or a dye to provide a characteristic color. [0047] The skin disinfecting formulations of the invention may be prepared in 4 individual Steps and in three separate vessels. Step 1 involves the mixing of the alcohol, water, and thickening agent. The thickening agent (Methocel Cellulose) is dispersed in the alcohol/water mixture at ambient temperatures. The subsequent mixture is agitated until the thickening agent is fully dissolved and no granulation remains. In step 2, a separate container is used which is suitable for heating the various emulsifiers and moisturizing agents. The emulsifier mixture may include one or more of the following methylparaben, propylparaben, isopropyl palmitate, mineral oil, incroquat CR, dimethicone-350, and Incroquat BTMS. The emulsifying agents are heated to 60-85° C. with mixing until all the ingredients are melted and thoroughly mixed. In Step 3 a vessel of water and glycerin is heated to 50-80° C. with mixing. The heated ingredients from Step 2 and any fragrance or colorant is then added with vigorous mixing to the glycerin/water solution of Step 3. The water/glycerin/emulsifier solution is then cooled to below 35° C. with continued mixing. Finally, in Step 4 the water/glycerin/emulsifier mixture in Step 3 is added to the alcohol/water/thickening agent mixture in Step 1 and mixed thoroughly. Preservatives are then added to the solution including one or more of the following: benzethonium chloride; benzalkonium chloride; and CHG. The solution is mixed continuously until a homogenous mixture is achieved. [0000] Biocompatibility [0048] The skin disinfecting formulations of the present invention were prepared with the ingredients as shown in Table I. The formulations were mixed in the manner described above. In each formulation, ethyl alcohol was used as the primary antimicrobial agent. Additional preservatives include benzethonium chloride, benzalkonium chloride, and CHG. TABLE I Antimicobial Formulation Compositions for the present invention Compositions are listed weight/100 weight solution Ingredient Formula A Formula B Formula C Formula D Formula E Formula F Formula G Formula H Ethyl alcohol 72.188 72.188 76.500 72.188 72.188 72.188 72.188 72.188 Cellulose (Methocel) 1.005 1.005 1.000 1.005 1.005 1.005 1.005 1.005 Incroquat BTMS 0.100 0.100 0.200 0.200 0.200 0.200 0.200 0.200 Mineral Oil 0.0100 0.0100 0.100 0.100 0.100 Dimethicone - 350 0.010 0.015 0.015 0.015 0.015 0.015 0.015 Benzethonium 0.099 0.099 0.099 0.099 0.099 0.099 0.099 0.099 Chloride Incroquat CR 0.051 0.050 0.050 0.050 0.050 0.050 Benzalkonium Chloride 0.099 0.099 0.099 0.099 0.099 0.099 0.099 0.099 Glycerin 0.708 0.700 0.700 0.700 0.000 0.000 0.700 0.700 Germaben II 0.030 0.030 0.030 0.030 0.030 0.030 0.030 Purified Water 25.196 25.458 20.905 25.223 25.423 25.298 25.141 25.223 CHG (20% Solution) 0.090 0.090 0.090 0.090 0.090 0.090 0.090 0.090 Isopropyl Palmitate 0.202 0.200 0.200 0.200 0.200 0.200 0.200 0.200 Fragrance 0.030 0.030 Hexetidine 0.002 0.002 0.002 0.002 0.002 lincroquat B65C 0.050 0.050 Propylene Glycol 0.500 0.700 Triclosan 0.002 Petrolatum 0.202 Incroquat CTC30 0.100 Squalane 0.025 Total 100.000 100.000 100.000 100.000 100.000 100.000 100.000 100.000 [0049] Formula C of the present invention was tested for primary dermal irritation and skin sensitization, based upon procedures described in ISO 10993-10: 1995 Standard, “Biological Evaluation of Medical Devices, Part 10—Tests for Irritation and Sensitization.” Ten test guinea pigs were patched with the test article and five guinea pigs were patched with a control blank. The bandages and patches were removed after six (6) hours of exposure. After a 24 hour rest period, each site was observed on each animal for erythema and edema. This procedure was repeated once a week for three weeks for a total of three applications. Following a two week rest period, the test animals were topically patched with the appropriate test article containing Formula C and the control blank on the control animals. The patches were removed after 6 hours of exposure. The dermal patch sites were observed for erythema and edema at 24, 48 and 72 hours after patch removal. Each animal was assessed for a sensitization response based on dermal observation scores illustrated in Table II. TABLE II Dermal Application Observations 24 Hours 48 Hours 72 Hours ANIMAL # ER ED ER ED ER ED TEST GROUP 2078 1 0 0 0 0 0 2079 0 0 1 0 1 0 2080 0 0 1 0 0 0 2081 0 0 0 0 0 0 2082 0 0 0 0 0 0 2083 0 0 0 0 0 0 2084 0 0 1 0 0 0 2085 0 0 0 0 0 0 2086 0 0 0 0 0 0 2087 1 0 0 0 1 0 Total of Scores 2 3 2 Severity (Total/10) 0.2 0.3 0.2 Incidence % 20% 30% 20% NEGATIVE CONTROL GROUP 2088 0 0 0 0 0 0 2089 0 0 0 0 0 0 2090 0 0 0 0 0 0 2091 0 0 0 0 0 0 2092 0 0 0 0 0 0 Total of Scores 0 0 0 0 0 0 Severity (Total/10) 0 0 0 0 0 0 Incidence % 0% 0% 0% [0050] The application sites were observed for irritation and sensitization reaction, as indicated by erythema and edema. The sites were gently wiped with a 70% alcohol soaked gauge sponge prior to each scoring period. The scoring criteria are listed below in Table III. TABLE III Dermal Observation Scoring ERYTHEMA EDEMA 0 = No erythema 0 = No edema 1 = Slight erythema 1 = Slight edema 2 = Well defined erythema 2 = Well defined edema 3 = Moderate erythema 3 = Moderate edema 4 = Severe erythema to slight eschar 4 = Severe edema formation [0051] The test results were based upon incidence and severity of the sensitization reaction. Individual animal scores of one (1) or greater in the test group generally indicate sensitization, provided scores of less than one (1) are observed on the control animals. An effect interpreted as “irritation” is generally observed at 24 hours, but diminishes thereafter. The results are summarized in Table IV. TABLE IV Irritancy Test results for Formula C Test Results Primary Dermal Irritation Slight Irritant (Undiluted) Sensitization Non sensitization [0052] The results of the test indicate that Formula C has a 20% incidence dermal response with a 0.2 severity index at the 24 hour time point; a 30% incidence with a 0.3 severity index at the 48 hour point; and a 20% incidence with a 0.2 severity index at the 72 hour point. However, the pattern of responses was irregular and did not repeat in every animal from 24 to 48 hours and therefore the response at 24 hours was categorized as an irritation. While a sensitization reaction could not be completely ruled out, Formula C had a slight potential for irritation when applied in semi-occluded conditions and a very low potential for sensitization, it was therefore classified as acceptable in regard to dermal sensitization. [0000] 21 Day Cumulative Irritancy and Delayed Challenge Test [0053] The relative skin irritation potential of Formula C solution was compared with three commercially available skin disinfecting formulations (Formulas X, Y and Z). Formulation X is the subject of U.S. Pat. No. 6,090,395 and consists generally of a rinse-less 61% ethanol and 1% CHG solution. Formulation Y is a 4% CHG solution, and Formulation Z, the subject of U.S. Pat. No. 6,110,908, is a brush-free 70% ethanol solution. The formulations were applied to the upper back of twenty-six (26) healthy volunteers daily for twenty-one (21) days, and remained in contact with the skin for twenty-four (24) hours with each application. Dermal irritation was evaluated daily by a dermatologist using the following scoring scale: 0=negative +=equivocal reaction (0.5) 1=erythema 2=erythema and induration 3=erythema, induration and vesicles 4=bulae [0060] Table V presents the cumulative irritancy scores for the twenty-six (26) healthcare volunteers over the course of the twenty-one (21) day study. TABLE V Irritancy scores for 21 Day Cumulative Irritancy Assay and Delayed Challenge Formulation Formulation Formulation Formulation C X Y Z Irritancy 3 47 0 147 Scores [0061] Formula C was classified as a “mild material” under occlusive conditions. The irritation score was not different for Formula Y, but significantly less than the patented formulations X and Z. [0000] Sensitization Phase [0062] Formula C and the three commercial test formulations were applied to a naïve site, and irritancy scores were taken at forty-eight (48) and ninety-six (96) hours post application to determine the level of contact sensitization. The scores are presented in Table VI. TABLE VI Formula C Formula X Formula Y Formula Z Scores 0 4.5 0 2.5 [0063] The results of the test again showed that the formulation of the present invention, formula C, had no potential for contact sensitization. The scores in Table VI are the sum of the scores at 48 and 96 hours only. [0000] Antimicrobial Effectiveness Test [0064] In Vitro Antimicrobial Efficacy of Formula C [0065] The efficacy of Formula C as an antimicrobial formulation was tested at 70% ethyl alcohol. The study evaluated the effectiveness of Formula C solution as a surgical scrub and hand antiseptic against broad-spectrum microorganisms. The study brought into contact Formula C with a population of organisms for a specific period of time at a specific temperature. The organisms included gram positive and gram negative bacteria, yeast, and molds that are commonly implicated in surgical wound infections. The percent reduction from the initial population was calculated for each of the organisms. The population reduction is presented in Table VII. TABLE VII In-vitro Time Kill Study at Full Strength (Log Reduction) Formula Formula C Formula D Formula F Formula G Formula X Formula Z Gram Positive Bacteria Staphylococcus aureus 15 seconds >6 log >6 log >6 log >6 log >5 log >4 log 30 seconds >6 log >6 log >6 log >6 log >5 log >4 log Staphylococcus epidermidis 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Gram negative bacteria Enterococcus faecalis 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Escherichia coli 15 seconds >6 log >6 log >6 log >6 log >6 log >3 log 30 seconds >6 log >6 log >6 log >6 log >6 log >3 log Enterobacter cloacae 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Pseudomonas aeruginosa 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Proteus vulgaris 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Klebsialla pneumoniae 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Serrtia marcescens 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log Yeast Candida albicans 15 seconds >6 log >6 log >6 log >6 log >6 log >4 log 30 seconds >6 log >6 log >6 log >6 log >6 log >4 log [0066] Formulations C, D, F, and G, of the present invention, with moisturizer provided rapid antimicrobial kill of broad-spectrum microorganisms with greater than log 6 microbial kill in 15 seconds. In comparison, the patented formulations X (U.S. Pat. No. 6,090,395) and Z (U.S. Pat. No. 6,110,908) provided less effective kill rates depending on the species of bacteria examined. The present invention showed an uncommon effectiveness against one of the more deleterious Staphylococcus strains, Staphylococcus aureus. All formulations of the present invention had a greater than log 6 reduction of Staphylococcus aureus, while Formula X managed a log reduction of greater than 5, an order of magnitude less effective and formula Z was less effective by two orders of magnitude having a log reduction of greater than 4. [0067] In Vitro Minimum Inhibitory Concentration, Formula C of the Present Invention [0068] In another study the minimum inhibitory concentration of Formula C was investigated. Formula C was used as the (test solution), and 70% ethyl alcohol solution as the (control solution) were diluted with a trypticase soy broth microbial growth media. Subsequent dilutions had the concentration calculated in ppm. Each concentration was challenged with an equal volume of microbial inoculums. After incubation the lowest concentration showing “No-Growth” was recorded as the Minimum Inhibitory Concentration. At full strength both Formula C and a 70% ethyl alcohol solution contain 70,000 ppm. TABLE VIII Minimum Concentrations of Formula C and 70% Ethyl Alcohol to Exhibit Antimicrobial Activity 70% ethyl Organisms ATCC or CI* Formula C alcohol Acinetobacter baumannii 19606 182 ppm 4375 ppm Acinetobacter baumannii 061901 Ab1* 273 ppm 8750 ppm Bacteroides fragilis 25285 273 ppm 8750 ppm Bacteroides fragilis 061901Bf2* 547 ppm 8750 ppm Candida albicans 10231 1094 ppm 17500 ppm Candida albicans 040400Ca2* 1094 ppm 17500 ppm Candida tropicalis 750 1094 ppm 17500 ppm Candida parapsilosis 040400Cp2* 1094 ppm 17500 ppm Enterobacter aerogenes 13048 547 ppm 8750 ppm Enterobacter aerogenes 040400Ea1* 182 ppm 8750 ppm Enterococcus faecalis 29212 273 ppm 8750 ppm Enterococcus faecalis 040400Esp17* 273 ppm 8750 ppm Enterococcus faecium 51559 183 ppm 8750 ppm Enterococcus faecium 061901Efm1* 273 ppm 8750 ppm Escherichia coli 11229 91 ppm 8750 ppm Escherichia coli 051599Ec* 68 ppm 8750 ppm Escherichia coli 25922 68 ppm 8750 ppm Escherichia coli 070399Ec* 137 ppm 8750 ppm Haemophilus influenzae 19418 183 ppm 5833 ppm Haemophilus influenzae 121699Hi* 46 ppm 5833 ppm Klebsiella oxytoca 43165 183 ppm 8750 ppm Klebsiella oxytoca 061901Ko1* 183 ppm 8750 ppm Klebsiella pneumoniae 13883 68 ppm 4375 ppm Klebsiella pneumoniae 06190Kpn1* 137 ppm 8750 ppm Micrococcus luteus 7468 17 ppm 8750 ppm CI*—Clinical isolate [0069] The data from Table VIII clearly illustrates that Formula C inhibits bacteria growth at a lower concentration than a 70% ethyl alcohol solution. The greater than fifteen fold growth inhibition activity of Formula C is largely attributable to the cocktail of antimicrobial agents used as preservatives. [0070] In Vivo Antimicrobial Efficacy [0071] Formula C was tested under the US Food and Drug Administration Tentative Final Monograph (TFM) for Effectiveness Testing of a Surgical Hand Scrub. This study evaluates the antimicrobial efficacy of one (1) test product and three (3) reference products for use as surgical scrubs. The procedure followed is described in the TFM for Presurgical Scrub Preparations (FR 59 [116], 17 Jun. 1994: pp. 31455-31448), with the objective of determining whether the test products would satisfy the critical indices of the TFM, such as: An immediate one (1) log 10 reduction in microorganisms on Day 1; An immediate two (2) log 10 reduction in microorganisms on Day 2; An immediate three (3) log 10 reduction in microorganisms on Day 5; And that microbial counts from the samples taken approximately three (3) hours to three (3) hours and thirty (30) minutes AND approximately six (6) hours to six (6) hours and thirty (30) minutes post-scrub not exceed the baseline counts. [0076] The study was conducted to evaluate the antimicrobial effectiveness of Formula C solution compared to Formulas X and Z, and a combination of Formula C with 4% CHG. The results are presented in Table IX. TABLE IX FDA Approved Hand Scrub Efficacy Test Immediate Log Formula C Reduction Formula C with 4% CHG Formula X Formula Z Day 1 1.76 2.07 1.63 0.35 Day 2 2.31 2.98 2.22 1.21 Day 3 3.03 3.47 2.52 2.75 [0077] The Comparative antimicrobial efficacy test data presented in Table IX, tested four different surgical hand scrubs. The data is reported as the immediate log reduction in microbial counts per hand when sampled one minute following the daily scrub over a five day period. Log reduction relates to a 10-fold or one decimal or 90% reduction in numbers of recoverable bacteria in a test food vehicle, that is a 1 log reduction would reduce the number of bacteria 90%. This means, for example, that 100 bacteria would be reduced to 10 or 10 reduced to 1. Table X represents the percent reduction of bacteria for logs one through five. TABLE X Microbial Log Reduction Log Reduction Chart Log Reduction % Reduction of Bacteria 1 90 2 99 3 99.9 4 99.99 5 99.999 [0078] Formula C produced significant immediate log reduction 1.76 on test day 1, 2.31 on test day 2 and 3.03 on test day five (5). The microorganism population from the Formula C sample, was taken six and a half (6.5) hours following the scrub innoculation, and did not return to pre-scrub microbial baseline levels. This data indicates that Formula C met the criteria indices of the FDA Tentative Final Monograph for a surgical scrub. The test data also confirmed that the integrated product of Formula C and 4% CHG is the best practice for a surgical scrub. The integrated products produced significant immediate log reduction 2.07 on test day 1, 2.98 on test day 2 and 3.47 on test day 5. The test data also indicates that Formula X (U.S. Pat. No. 6,090,395) and Formula Z (U.S. Pat. No. 6,110,908) did not meet the criteria indices of the FDA as specified in the Tentative Final Monograph for a surgical scrub product. [0079] It will be apparent that the present invention has been described herein with reference to certain preferred or exemplary embodiments. The preferred or exemplary embodiments described herein may be modified, changed, added to, or deviated from without departing from the intent, spirit and scope of the present invention.	A method of switching a speech channel in a mobile telephone system comprising an interface between a Base Station System (BSS) ( 1 ) communicating with a Mobile Switching Center (MSC) ( 5 ) via a transmission connection ( 3 ), where the speech channels of an originating subscriber ( 8 ) and a dialled-up subscriber ( 9 ), both of whom are located on the BSS ( 1 ) side of the transmission connection ( 3 ), are connected in a local switcher ( 2 ).	0
BACKGROUND OF THE INVENTION 1. Technical Field This invention relates to downhole working in boreholes, as in the case of oil or geothermal wells. 2. Background Information During prospecting and production operations, it is often necessary to anchor a tool in a borehole at a chosen depth. More generally, many types of tools are designed to be actuated at a well-determined depth: this is the case, for example, of a cement dump bailer which must be discharged at the depth at which a well is to be closed off. The conventional procedure consists in first lowering the tool by means of a cable to the desired depth determined by the unreeled length of cable. The tool is then anchored in the production tubing. Then, the actual control of the tool is achieved by repeated pulling exerted from the surface via the cable until the failure of one or more pins. When the cable used is an electric cable, it is possible to use explosive means controlled electrically from the surface. All prior art systems are of the abrupt-action type, which is considered to be necessary in this technique in order to avoid inadvertent triggering of the tool other than at the desired depth. For traction actuation, the calibration of the fracture pin(s) must be defined carefully and the tool control operations require the securing of the tool in the well. As regards explosive techniques, which are applicable only when an electric cable is used, they also require quite rigorous safety precautions well known to those of the art. Finally, certain wells having a particular configuration oppose the use of conventional downhole tool triggering techniques. This is the case in particular of wells which exhibit a local restriction beyond which the tool must be triggered. This restriction makes difficult and even impossible the passage of a tool equipped with anchoring means. It may also be mentioned that the control of a tool by pulling on the cable is poorly suited to deviated wells. SUMMARY OF THE INVENTION The present invention provides a satisfactory solution to these problems. It is thus a primary object of the invention to provide means for triggering a tool in a borehole which reconciles a soft action mode with as great a reliability as prior art techniques. Another object of the invention is to provide triggering means which are soft and yet quite rapid, notably for the control of tools such as cement bailers. A further object of the invention is to allow the actuation of tools at depths and/or in wells in which this has hitherto not been possible. Finally, it is an object of the invention to provide a technique for triggering a tool in boreholes, capable of being easily adapted in the field according to requirements. For this purpose, the invention proposes first of all a method for actuating a tool in a well at a chosen depth. This method comprises the following operations: (a) Determining the temperature of the well at the chosen depth. (b) Equipping the tool with a control element made of a material capable of melting at a tempeature near the temperature thus determined. (c) Lowering this tool to the desired depth, and waiting there for the actuation of the tool by the melting of the control element. This technique is effective in every case, but is particularly useful in the case of wells having a restricted and/or highly deviated passage. In current embodiments of the method, energy is stored in the tool and is then released by the melting of the control element. At the present time, it is considered desirable that the melting temperature of the material forming the control element be defined with an accuracy of plus or minus 5° C., and preferably plus or minus 2° C. approximately. In practice, a material is chosen which has a melting temperature equal to or slightly lower than the temperature of the well at the desired depth. This can be determined by direct measurement using a temperature probe or by the measurement or even the estimation of the temperature gradient along the well. The waiting time to be complied with to obtain the triggering of the tool is related to the time necessary for the thermal equilibrium between the tool and the well fluid when the tool has reached the desired depth. It is generally a fraction of this time. The invention also provides downhole tools allowing the implementation of this method. In a general definition of such a tool, it comprises, in combination, mechanical means capable of being loaded on the surface for storing energy, as well as at least one control element melting at a predetermined temperature and whose melting ends said storage. According to another definition, the tool comprises two parts normally subject to relative motion, as well as a control element made up of a fusible part securing the two parts against said relative motion. In a first embodiment of the tool, the two parts are subjected to relative motion in relation to each other upon encountering an elastic return. The control element comprises a lock such as a fusible pin securing the two parts in relation to each other in the tensioned position of the elastic return. One of the current requirements in the manipulation of tools lowered into wells is the anchoring of these tools in the well. It is readily possible to provide anchoring means by equipping one of the parts with jaws supported movably with axial sliding on a rod terminating in an expansion cone toward which the jaws are loaded by the elastic return. The anchoring can thus be obtained without requiring repeated pulling by means of the cable or equivalent means. According to another embodiment of the invention, one of the two parts of the tool forms a receptacle containing the other part against movement under the action of gravity. One thus obtains, for example, a cement bailer consisting of a receptacle provided with an opening which can be closed by a plug. The applicant has observed that certain special metallic alloys exhibiting all the desired properties for use in wells are capable of melting practically cleanly at any chosen temperature between about 45° and 400° C., the temperature accuracy being ±2° C., or better. BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will appear from the following detailed description given in connection with the appended drawings in which: FIGS. 1A and 1B represent an anchoring tool according to the present invention; and FIG. 2 represents a cement bailer according to the invention. DESCRIPTION OF PREFERRED EMBODIMENTS Equipment lowered into oil and/or geothermal wells operates under very specific conditions in which it undergoes exceptional pressure and temperature stresses. Thus, to actuate a tool in a well it is recognized that it is necessary to: equip this tool with an element capable of breaking under a well-determined load, which has to be adjusted, lower this tool to the desired depth, anchor it there, exert repeated pullihng from a distance, generally by means of a cable, until the fracture of said element. In certain cases, as in the case of cement bailers, it is possible to use explosive means remote controlled by an electric cable from the surface. The explosion then opens the gate which releases the cement at the desired depth in the well. In addition to the fact that it has no general application, this exlosive technique has serious drawbacks related, firstly, to the existence of the explosion and, secondly, to the combustion scrap and other debris resulting therefrom. The present invention offers a very different solution, unknown up to the present time, for the triggering of tools lowered into oil or geothermal wells. This solution is based upon the application of specific metals or metallic alloys capable of melting at a well-determined temperature definable within a narrow range such as ±5° C., or better, ±2° C. Although different types of materials may meet this condition, the applicant presently prefers to use the "fusible" alloys sold by Societe Braconnot in Paris, France. By varying the proportions of the elements composing this alloy, it is possible to define with great accuracy its melting point, which can go down to about 45° C. This material is easily machinable and has melting properties sufficiently clean to give satisfaction. It is known that wells, and notably oil wells, are the scene of a temperature gradient, the temperature increasing on the average by about 1° C. every 30 meters. Although this temperature variation is not rigorously linear, it remains substantially monotonic and exhibits, with depth, only plateaus or small variations. It has been found that this situation is compatible with the use of the melting of an alloy as defined above for the release of energy stored on the surface and in the tool. Under certain circumstances, very precise measurements are made of the temperature profile of a well as a function of depth, to within 1° C. Independently of precise measurements, for any well, the temperature of the well as a function of depth is generally known to within a few degrees. When it is desired to actuate a tool in a well at a chosen depth, it is thus possible to determine the temperature of the well at this depth to within 1° or 2° C. As previously indicated, the tool is equipped with a control element made of a material such as the abovementioned alloy, chosen so that its melting temperature is near the temperature of the well thus determined at the desired depth. The tool is lowered to this depth to await actuation by the melting of its control element. It has also been observed that any tool penetrating into a well does not immediately acquire the temperature of the well at its location. The latency time necessary for the tool to be in thermal equilibrium with the well when the tool is stopped at a well-determined location is currently of the order of ten minutes or so. The fusible material is thus chosen so that its melting temperature is equal to or preferably lower than the temperature of the well at the desired depth. It has then been observed that the melting takes place in a few minutes, thereby actuating the tool. The energy stored on the surface in the tool can be of various kinds: it may consist of a hydrostatic pressure difference or the energy of a precalibrated spring, for example. In the first case, a material is stored in the tool that has a density higher than the density of the fluid filling the well at the desired depth. The fusible control element will, by opening a gate, discharge this material from the tool. The energy storage is then comparable in this case to the storage of matter and this matter is associated with energy which depends on the difference in the densities of said matter and of the fluid filling the well. This is the case of a cement dump bailer or any other body having a density higher than that of the fluid in the well. Other examples include sand or gravel. The invention is applicable to most downhole tools in which it is necessary to maneuver a liner under difficult conditions or when shocks are detrimental to its operation, which rules out the use of prior art cables. This corresponds to the second case, namely the mechanical storage of energy by means of a precalibrated spring or equivalent means. FIGS. 1A and 1B illustrate a first embodiment of the present invention allowing the anchoring of a tool in a well. The tool is illustrated inside a production tube CP. It comprises a head bushing 101 equipped at one end with a flange 100 and on the other end with attachment means 102. To lower it into the well, the head 101 is fixed to the end of a nonconducting cable by means of a setting tool. The body of the tool is otherwise of a generally cylindrical form. Below the element 102, it includes a solid cylinder 103 followed by another flange 104. This flange defines the maximum outer diameter of the tool in its rest position before anchoring. The shoulder 104 is followed by a conical body 111 which tapers down to a central cylindrical rod 110. At its lower end, the rod 110 is provided with a flange 112. On the rod 110 is slidably mounted an annular body member 120 whose upper part defines an annular recess 121. Into this recess 121 are inserted the feet 122 and 122A of two anchoring elements 123 and 123A whose other ends form dogs or jaws (operating in extension) 124 and 124A. The insides of the jaws 124 and 124A are flared upwardly. In the rest position, they bear on the beginning of the expansion cone 111. The bottom of the annular member 120 forms a stop for a spring 130 which also bears on the upper shoulder of the flange 112 already mentioned. In the rest position of the tool, a pin 140 goes through the rod 110 to secure the annular member 120 in a position in which the spring 130 is under compression. The pin 140 is made of a fusible material according to the invention. In operation, the tool is lowered to the desired depth after having placed therein a pin 140 melting at the corresponding temperature. After the melting of the pin 140, which takes place after a few minutes, the spring 130 loads the ring 120 upwardly which in turn pushes the jaws 124 and 124A so that they are moved outwardly by the cone 111 and engage on the production tubing CP, thus anchoring the tool. This anchoring function is thus obtained without any shock. Moreover, the means used allow a significant movement of the jaws 124 and 124A between their rest position and their anchoring position, whereas generally prior-art means were incapable of doing so. The arrangement according to the invention thus makes it possible to achieve satisfactory anchoring beyond a restriction, owing to the great range of movement allowed for the jaws 124 and 124A. The second embodiment of the invention is illustrated in FIG. 2 in the form of a cement bailer. The head piece 203 is provided with a flange 202 and a threaded upward extension 201. The lower end of head piece 203 forms a cover 204 perforated at 205. A cylindrical tube 210 is secured inside the cover 204 by a pin 206. A pad 211 secured on the bottom of the cylindrical tube 210 by a pin 212 applies a disk 240 against the end of the tube. This disk 240 is made of a fusible material according to the invention. In this case also, a tool of this type is capable of different applications, notably those consisting in cementing a well beyond a restriction. Furthermore, the use of this cement bailer is faster than in the prior art where it was often necessary to wait for the cement to begin solidifying before bringing in another cement bailer to continue the cementation. Two examples are given below to illustrate respectively the implementation of the two tools described. EXAMPLE 1 Tools as illustrated in FIGS. 1A and 1B have been provided with fusible pins, one melting at 70° C. and the other at 120° C. The compositions of the alloys used for the pins were the following: at 70° C.: 50% bismuth 25% lead 12.5% zinc 12.5% cadmium at 120° C.: 1% zinc 55% bismuth 44% lead It was possible to install these anchoring tools under very difficult conditions, namely in a well deviated in depth, equipped with a production tubing having an intermediate part of smaller diameter than the upper and lower parts. These tools all proved satisfactory, whereas prior art anchoring means could practically not operate. EXAMPLE 2 A tool according to FIG. 2 was made with, for the part 240, a disk of "ceroben" of 2-mm thickness and 40-mm diameter which melted at 120° C. Its composition was the same as the alloy indicated in Example 1. In this manner, twelve cement bailers (eleven for cement and one for sand) were placed successively at a depth of about 5000 meters, successfully and very rapidly. U.S. Pat. No. 4,390,291 gives the composition of alloys melting at various temperatures. Of course, the present invention is not limited to the particular tools just described. Based upon the storage of energy by a spring as used in FIG. 1, it is possible to provide a fusible pin whose melting will in turn drive a second stronger pin which will in turn trigger the tool, but with a greater energy, stored for example in a second spring. One thus achieves mechanical amplification to obtain the energy required for triggering the tool. Conversely, instead of the "gate" 240 of the tool in FIG. 2 being entirely in fusible material, it would also be possible to provide a gate loaded to open by means of an elastic return, or simply by gravity, and kept in place by a fusible lock. The invention can also be applied to other types of tools and in particular to the downhole placing of fragile electronic instruments or the downhole actuation of material samplers.	A downhole tool is actuated at chosen well depth by selection of a control element that melts at the chosen depth well temperature. In one form of tool, a fusible pin melts to release spring-loaded jaws which move against an expansion cone to anchor the tool in the well. In another form, a fusible receptacle cover melts to release a quantity of dense fluid under action of gravity. Suitable control elements are formed of bismuth, with lead and zinc.	4
FIELD OF THE INVENTION [0001] This invention relates generally to the field of vehicle steering systems, and more particularly relates to an electric power assist steering system having an electric motor flexibly coupled to a vehicle steering system. DESCRIPTION OF THE RELATED ART [0002] A Typical Steering System [0003] A typical steering system for a motor vehicle is illustrated in FIG. 1. The steering system 1 has rotating steering wheel 2 in the passenger compartment of the vehicle mounted to steering column 3 that is operatively connected to wheels 4 via steering assembly 5 . In order to reduce the amount of driver effort (i.e., torque) that is required to rotate the steering wheel, many steering systems include a power-assisted actuator. The actuator assists the operator with rotation of the steering wheel to overcome opposing forces such as road load forces on the road wheels and friction forces in the steering assembly. The amount of power assistance generally varies depending on the speed of the vehicle and the amount of effort applied by the vehicle operator to the steering wheel. Conventional power assist steering systems typically employ either hydraulic power assist or electric power assist mechanisms. Electric power assist mechanisms are being used in an increasing number of vehicles due to their reduced size and higher energy efficiency than hydraulic mechanisms. [0004] Electric Power Assist Systems [0005] An electric power assist steering (EPAS) system employs an electric motor for applying a controlled amount of torque to the steering assembly to assist the operator with rotation of the steering wheel. For example, the system illustrated in FIG. 1 includes electric motor 6 for power assist, and controller 7 . The steering assembly may be a rack and pinion type that converts angular rotation of the steering wheel into a sliding motion of a rack to steer the wheels. The rack interacts with teeth on an assist pinion that is driven by the output shaft of motor 6 in response to signals from controller 7 . The signals from controller 7 are designed to provide a relatively constant torque at the driver pinion. [0006] An example of an EPAS rack and pinion assembly 10 is illustrated in FIG. 2. Inner tie rods 12 are connected to a rack and pinion mechanism contained within housing 14 . Gear box 16 contains a gear reduction mechanism for the assist pinion. Electric motor 18 is rigidly mounted to gear box 16 to power the assist pinion via the gear reduction mechanism. The motor output shaft directly connects to an input shaft, which may be implemented as a worm gear shaft, in the gear reduction mechanism. A driver pinion torque sensor, as well as various other sensors, may also be included, but the driver pinion and sensors are not shown to simplify the present description. The measured torque at the driver pinion serves as an approximation of the input torque applied to the steering wheel by the vehicle operator and is commonly used to determine the amount of torque assist to be provided by the electric motor to the assist pinion. Further information about electric power assist steering systems can be found in various patents and literature references, including but not limited to U.S. Pat. No. 5,743,352, to Miller et al., and U.S. Pat. No. 6,250,419, to Chabaan et al., both of which are incorporated by reference as if reproduced in full herein. [0007] Concerns over fuel efficiency have led to the production of smaller vehicles and/or vehicles with more aerodynamic shapes to reduce wind resistance. Due to limitations on reducing the size of the passenger compartment and concerns about passenger compartment comfort, the size of vehicle engine compartments has been reduced and their shape varied to accommodate smaller vehicle sizes and/or new vehicle body designs. The demand for more features while maintaining or increasing vehicle performance have led to an increasing number of components in smaller vehicle engine compartments which have various shapes. [0008] An electric power assist steering system offers variable assist capabilities, more efficient energy consumption, reduced mechanism complexity, increased reliability, and responsive on-demand steering assist, as well as other advantages. Conventional steering systems and components are available from TRW, having facilities in Livonia Mich., USA, Delphi Automotive Systems, having facilities in Saginaw, Mich., USA, and NSK Ltd., having offices in Tokyo, Japan. However, the electric motor increases the size of the system, and rigid attachment of the electric motor to the rack and pinion assembly leaves little flexibility for more efficient engine compartment design and component placement. For example, the typical steering gear has a length of about 1520 mm, inclusive of the tie rods, while a typical power steering motor has a length of at least about 150 mm and a diameter of at least about 100 mm. A conventional power steering system constructed in this manner makes an unwieldy combination. Further, the bulky projection created by the motor rigidly mounted to the assembly makes it more difficult to work on, install, or remove the engine, steering system or other vehicle components in the engine or power source compartment. [0009] As used herein, engine compartment shall refer to the vehicle compartment for an internal combustion engine power source, hybrid internal combustion engine with electric motor power source, or other vehicle power source type. [0010] Accordingly, it is desired to provide an electric power assist steering system that increases the engine compartment utilization efficiency while also increasing the ease of repair, installation, and removal of engine, steering system and other vehicle components in the engine compartment. SUMMARY OF THE INVENTION [0011] In accordance with the teachings of the present invention, a steering system and method of installing a power assist steering assembly in a vehicle are disclosed. According to one aspect of the present invention, an electric power assist steering system is provided in which an electric motor is operatively engaged via a flexible coupling with the remainder of the steering system for supplying torque assist. In another aspect, a motor for power assist steering systems is disclosed having a rotating output shaft and a flexible shaft connected thereto for transferring power. A method of installing a steering system in a vehicle is also disclosed wherein the electric motor is installed independently of and then flexibly coupled to the remaining steering system components. The electric motor output shaft is located at a remote location from the pinion shaft or input shaft of the pinion gear reduction mechanism. The steering system, motor, and method of the present invention provide for greater flexibility in engine compartment design and component placement efficiency, and facilitate repair, installation, and removal of engine and steering system components. [0012] These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings. It is to be understood that both the preceding summary and the detailed description that follows are intended merely to be exemplary and to further explain the invention claimed. The invention may be better understood by reference to the following detailed description read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0013] [0013]FIG. 1 illustrates a typical vehicle steering system. [0014] [0014]FIG. 2 illustrates a rack and pinion steering mechanism of an electric power assist steering system, in which the electric motor is rigidly attached to the assist pinion gear reduction mechanism. [0015] [0015]FIG. 3 illustrates an embodiment of a rack and pinion steering mechanism of an electric power assist steering system of the present invention, in which the electric motor is flexibly coupled to the assist pinion gear reduction mechanism. [0016] [0016]FIG. 4 is an exploded perspective view of an embodiment of an assist pinion gear reduction mechanism housing, showing the worm drive gear detached therefrom. [0017] [0017]FIG. 5 is a perspective view of an embodiment of an assist pinion gear reduction mechanism housing, showing the worm drive gear inserted therein with its splined end projecting therefrom. [0018] [0018]FIG. 6 is a side elevation view of the end portions of an exemplary coupling for use with the present invention, in which a portion of the casing has been cut-away to reveal the flexible shaft. [0019] [0019]FIG. 7 is a cross-sectional end view of the end fitting of the coupling of FIG. 7 shown in exploded relationship to a set screw. [0020] [0020]FIG. 8 is a flow chart for an exemplary method of installing an electric power assist steering system in a vehicle in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION [0021] An embodiment of the present invention may be better understood with reference to FIG. 3. Rack and pinion mechanism 20 , such as that shown in FIG. 2, includes assist pinion gear reduction housing 22 that includes coupling fitting 24 for coupling 26 . Coupling 26 couples electric motor 28 to the assist pinion gear reduction mechanism. In this embodiment, a conventional electric motor used in electric power assisted steering mechanisms and a conventional assist pinion gear reduction mechanism and housing are used. Therefore the bolt holes on and dimensions of flanged plate 30 of the motor housing correspond to those of flanged plate 32 on gear reduction mechanism housing 22 . [0022] It has been surprisingly discovered that the assist motor can be remotely attached by a flexible coupling to the assist pinion without a substantial decrease in performance of the steering system. [0023] In a preferred embodiment, coupling 26 includes an outer flexible sleeve or conduit that contains a flexible shaft. The flexible shaft is connected to the motor output shaft at one end and to the gear reduction mechanism input shaft at its opposite end. The flexible shaft may be formed of steel or synthetic fiber that minimizes the loss of torque between the motor and pinion gear mechanism despite being flexible. Non-limiting examples of flexible couplings suitable for use with the present invention can be obtained from Motion Industries of Wichita Falls, Tex., and Dearborn, Ml, USA, and Stock Drive Products/Sterling Instrument of New Hyde Park, N.Y., USA. In addition to flexible shafts, it is contemplated that the electric motor may be coupled to the steering system via a single or double universal jointed shaft, in which the shaft has at least two rigid linear steel segments connected via at least one universal joint. A non-limiting example of a source for a suitable assist motor is Visteon Global Technologies, Inc. of Dearborn, Mich., USA or affiliate thereof, and a non-limiting example of a source for an assist pinion gear reduction mechanism is Nissei Corporation, Japan. [0024] With reference to FIG. 4, an example of an assist pinion gear reduction mechanism suitable for use with the present invention is illustrated. Gear reduction housing 40 provides for insertion of worm drive shaft 42 . Worm drive shaft 42 includes worm screw threads 44 that engage gears in housing 40 . Rotation of worm drive shaft 42 leads to rotation of assist pinion shaft 46 . [0025] With reference to FIG. 5, worm drive shaft 42 is rotatably mounted in housing 40 by bolt 48 . Shaft 42 may include threads on its outer perimeter, or some other attachment mechanism for connection to the sleeve or outer conduit of flexible coupling 26 . Worm drive shaft 42 preferably includes a splined hub 50 for connection to a corresponding fitting on the end of the flexible coupling shaft. A similar splined hub on the electric motor output shaft is connected to a corresponding fitting on the motor end of the flexible coupling shaft in like fashion. [0026] An Exemplary Flexible Coupling [0027] With reference to FIG. 6, an exemplary embodiment of a flexible coupling for use with the present invention is illustrated. Flexible shaft 62 is contained within flexible sleeve 64 , the latter being partially cutaway to show shaft 62 contained therein. Shaft 62 is continuous, but shown in cut and truncated form to facilitate illustration. Shaft 62 may have a length ranging from about 1 inch up to about 48 inches. However, in a preferred embodiment, shaft 62 is about 24 inches or less in length. Suitable flexible shafts are made of steel, and have diameters ranging from about 0.1 inch to about 0.75 inch depending on the operating requirements. In a preferred embodiment, the shaft has a diameter of about 0.25 inches for use in small to mid-sized cars. Larger diameter shafts may be required for larger vehicles. [0028] Flexible sleeve 64 may be formed of vinyl-covered steel, and its diameter will depend in part on the diameter of shaft 62 . For example, the diameter of shaft 62 may be ½ inch when the shaft is {fraction ( 1 / 4 )} inch or less in diameter. Sleeve 64 may contain bearings to prevent wear upon contact with shaft 62 when it is rotating. [0029] End fittings 66 and 68 are bonded to the ends of shaft 62 . With reference to FIG. 7, a cross sectional end view of end fitting 66 is illustrated. Fitting 66 includes a generally cylindrically shaped opening 70 which may be placed over the input hub of a power steering gear reduction mechanism, such as hub 50 in FIG. 5. Fitting 66 includes splines 72 on its interior wall designed to engage corresponding splines on an input hub. However, other gripping mechanisms may be employed or the interior wall of fitting 66 may be smooth. [0030] A bore 74 is provided in fitting 66 to provide for a set screw, such as screw 76 . Use of a set screw may require that the input hub on the power steering gear mechanism be sufficiently long to permit tightening of set screw 76 to the hub. More than one bore may be provided for a plurality of set screws, particularly for larger diameter shafts that may encounter high torque demands. Fittings 66 and 68 may be of plated steel or other suitable material. The sheathing for the flexible coupling may have an extended cowl at either end to cover the rotating fittings 66 and 68 . [0031] In general, the minimum operating radius of curvature for the flexible shaft increases with shaft diameter. As radius of curvature increases, the dynamic torque capacity of the shaft increases. Thus, it is preferred that the electric motor output shaft be aligned with the input hub of the power steering input shaft or gear in order to optimize the radius of curvature to the performance requirements. Performance data for exemplary flexible shafts is provided in Table 1 below. [0032] A preferred source for flexible shafts is Stock Drive Products/Sterling Instrument of New Hyde Park, N.Y., USA. Non-limiting examples include Catalog Numbers A 7Z10-N24433, A 7Z10-N24533, A 7Z10-N36533, A 7Z10-N30633, A 7Z10-N36633, A 7Z10-N24833, A 7Z10-N36833. As noted above, a single or double universal jointed shaft may be used in place of the flexible shaft, preferably including a flexible rubber sleeve over the joints. A preferred double universal jointed shaft may provide a maximum working angle of approximately 70 degrees, and is available from Belden Incorporated, Broadview, Ill., USA. Non-limiting examples of suitable double universal shafts for use with the present invention include Belden Incorporated part numbers DUJ375, DUJ500, DUJ625, DUJ750, UJ-DD375, UJ-DD500, UJ-DD625 and UJ-DD750. TABLE 1 PERFORMANCE DATA FOR EXEMPLARY FLEXIBLE SHAFTS Torsional Breaking Load For Straight Minimum Dynamic Torque Capacity Shafts, Shaft Operating Winding Direction (lb. In.) Input Winding Diameter Radius Radius of Curvature (In.) Direction (In.) (In.) 25 20 15 12 10 8 6 4 (lb. In.) 0.130 3.0 3.8 3.6 3.4 3.1 2.4 1.7 15 0.150 4.0 5.0 4.7 4.4 3.9 3.1 1.4 24 0.187 4.0 13.5 12.6 11.8 11.0 9.8 7.8 4.0 55 0.250 4.0 25.0 24.0 22.0 21.0 19.0 16.0 12.0 100 [0033] In a preferred embodiment, an electric motor is flexibly coupled to a conventional rack and pinion steering mechanism, which is incorporated into a conventional steering system. However, it is envisioned that the present invention may be adapted to column as well as dual pinion steering systems, and to many different vehicle types, such as but not limited to the Ford Focus, Saturn SUV, and Honda S2000. [0034] Exemplary Methods for Installing an Electric Power Assist Steering System [0035] In an embodiment, a power assist steering system is installed in a vehicle by installing the electric motor independently of the rack and pinion mechanism and/or gear reduction mechanism. For example, with reference to FIG. 8, in a first step 100 of an exemplary method, the rack and pinion mechanism is installed. In a second step 110 , an electric motor suitable for providing power assist to the rack and pinion mechanism is installed. In a third step 120 , the electric motor output is coupled to the input of the rack and pinion mechanism by connection of the flexible coupling to the electric motor output and to the input of the rack and pinion mechanism. [0036] Preferably, the electric motor is mounted away from heat and road splash, and the motor output shaft remains as “in-line” as possible with the power assist pinion input. In general, the higher the torque requirements, the more the motor output shaft should be in linear alignment with the power steering input shaft hub. By placing the motor closer to the electric power source, additional economies can be obtained. The flexible coupling provides for numerous variations in the method of installation, which may be optimized depending on the vehicle, engine, and other considerations. Some exemplary methods are described in Table 2 below. [0037] As one of skill in the art will recognize, the longer the flexible coupling between the motor output and steering gear input, the greater the potential loss of torque between the motor and input gear. Further, the dynamic torque TABLE 2 EXEMPLARY METHODS FOR INSTALLING AN ELECTRIC POWER ASSISTED STEERING SYSTEM OF THE PRESENT INVENTION IN A VEHICLE STEP NOTES Electric Install a suitable electric assist motor for providing Motor power to a compatible steering mechanism in the Installation desired engine compartment location, preferably away from road splash. The electric motor output shaft preferably faces in the general direction of the location where the steering mechanism is or is to be installed, but at a distance therefrom. Steering Install a steering mechanism in the desired engine Mechanism compartment location. The input shaft of the Installation steering mechanism should face in the general direction of the location where the electric power assist motor output shaft is or is to be installed, but is remote therefrom. The angle between the steering mechanism input shaft and the electric motor output shaft is preferably less than about 90 degrees, and in an embodiment less than about 15 degrees. This step may be performed before the Electric Motor is installed. Coupling Electric The electric motor may be coupled to one end of Motor To Steering the flexible coupling prior to its installation. Mechanism Alternatively, one end of the flexible coupling can be coupled to the steering mechanism input shaft prior to installation of the steering mechanism in the engine compartment. This latter technique may be helpful where the steering mechanism input shaft is hard to reach after installation. Connection of the free end of the coupling is done after both the electric assist motor and steering mechanism are installed in the engine compartment. In an alternative embodiment, the motor and steering mechanism are coupled together prior to installation, with the flexible coupling making it easier to manipulate the entire apparatus into the engine compartment. [0038] capacity is lower with a lower radius of curvature, so that the angle and distance between the motor output and steering gear input should be optimized for particular applications. In preferred embodiments, the distance between the motor output and the input gear is less than about 36 inches, and is preferably equal to or less than about 24 inches, and the angle between the motor output and the input gear is less than about 90°, and is preferably less than about 45°. In one embodiment, the flexible shaft is between about 1 inch and about 24 inches in length, and the angle between the motor output shaft and the gear input is between about 0° and about 30°. In another embodiment, the angle between the motor output shaft and the gear input is between about 0 degrees and about 15 degrees. Embodiments also include shafts of 6 inch and 12 inch length. [0039] While embodiments of a new electric power assist steering system and methods of installing same have been disclosed as examples herein, there could be a wide range of changes made to these embodiments without departing from the present invention. For example, it is envisioned that the reduction gear mechanism may be rigidly connected to the electric motor, and the output from the reduction gear mechanism flexibly coupled to an assist pinion input in the same fashion as the electric motor is flexibly coupled to the assist pinion gear reduction mechanism input shaft described above. Thus, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it be understood that it is the following claims, including all equivalents, which are intended to define the scope of the invention.	An electric power assist steering system includes an electric motor with an output shaft, and a flexible shaft operatively connected to the output shaft. In a preferred embodiment, the flexible shaft is also operatively connected to the input shaft of a pinion gear for a rack and pinion steering mechanism. The present invention increases the engine compartment utilization efficiency while also increasing the ease of repair, installation, and removal of engine, steering system and other vehicle components in the engine compartment.	5
This application is a division of application Ser. No. 08/994,507, filed Dec. 19, 1997. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and device to determine the alignment for the insertion of an instrument such as a pin, rod, nail, screw, wire, drill bit, or other implant into bony tissue using x-ray or fluoroscopy or the like to stabilize fractures or other bony tissue defects. More particularly, the method and device is designed for use by a surgeon to properly determine the point and trajectory of insertion of said instrument into a particular bone mass using an x-ray or fluoroscopic imaging device without the need to otherwise make multiple attempts to properly insert the instrument, such as a nail, pin, rod, screw, wire, drill bit, or other implant into the bony tissue. 2. Description of the Prior Art Every year, in the United States and worldwide, large numbers of surgical procedures are performed in which an instrument, such as a nail, pin, rod, screw, wire, drill bit, or other implant is inserted into a bony tissue mass to stabilize a fracture or defect in such bony tissue mass. The nail or screw strengthens the bone and holds the parts of the bone together. For example, such a technique is used to fix a hip fracture. Hip fracture fixation with either compression hip screws (CHS) or intramedullary interlocking nails is one of the most common orthopedic surgical procedures. The surgeon's goals are accurate reduction and stabilization of the fracture until bony union occurs. For purposes of illustration herein, examples regarding the insertion of a pin into the proximal femur of a person will be referred to. This should in no way be interpreted as a limitation on the scope of this invention. Rather, the present invention includes, without limitation, devices used for insertion of instruments, such as pins, screws, rods, nails, wires, drill bits, or other implants into any bony tissue of a person or animal. In one such surgical procedure, an incision is made through the skin of the hip to expose the femur starting at the tip of the greater trochanter. Using visual landmarks, the surgeon drills a guide-pin across the fracture into the femoral head. The surgeon checks the positioning of the guide-pin with an x-ray or fluoroscopic imaging device to determine if the positioning of the guide-pin is acceptable. If it is not, the surgeon must extract the guide-pin and reevaluate the insertion point and trajectory, then reinsert the guide-pin until its positioning is acceptable. When the guide-pin is in an acceptable position, a lag screw is advanced over the guide-pin into the femoral head to secure the bone for healing. A side plate is placed over the lag screw extender and secured to the lag screw and the femur for support and to compress the fracture. (See FIG. 2 a ). Another means of securing a femoral neck fracture is with the use of an intramedullary locking nail. In that surgical procedure, an incision is made over the trochanteric region. The entry point is prepared using an awl. A guide wire is inserted into the femur and the intramedullary nail is inserted over the guide wire into the femur. A device is used to align a lag screw through a guide sleeve which is brought into contact with the femur. The screw is visually oriented and the surgeon drills a guide-pin across the fracture into the femoral head. The surgeon checks the positioning of the guide-pin with an x-ray or fluoroscopic imaging device to determine if the positioning of the guide-pin is acceptable. If it is not, the surgeon must extract the guide-pin and reevaluate the insertion point and trajectory, then reinsert the guide-pin until its positioning is acceptable. When the guide-pin is in an acceptable position, lag screw is advanced over the guide-pin, through an opening in the proximal portion of the intramedullary nail, and into the femoral head. The guide-pin is extracted and the intramedullary nail is secured by drilling screws through openings in the distal portion of the intramedullary nail. An important part of both procedures is the placement of a compression or lag screw from the lateral side of the femur, through the femur, passing through the femoral neck, and into the femoral head. Inaccurate placement of the screw can lead to being misaligned with respect to the femoral head (see FIG. 1 ). To avoid this, surgeons commonly spend a significant portion of their operating time iteratively inserting, checking, removing, and re-inserting a guide-pin over which the screw will be passed until accurate positioning within the femoral head is achieved. Surgeons typically use fluoroscopic image intensifiers to determine the accuracy of their guide-pin placement in two planes of view, the anterior-posterior (“AP”) and the medial-lateral (“ML”) (see FIGS. 3 a & 3 b ). After satisfying themselves that the position of the guide-pin within the femur is accurate in one view, the fluoroscope is turned to the orthogonal view to check accuracy in that plane. If the wire or guide-pin is misplaced in the second view, the surgeon generally takes it out of the bone and reinserts it until satisfied with the position. By doing this, the surgeon loses reference of the initial view and must re-check the accuracy of the re-drilled guide-pin in both orthogonal views. The surgeon repeats this process until reaching an acceptable position. This iteration takes time and results in greater x-ray exposure for patients and staff. Additionally, the process of inserting, removing, and reinserting the guide-pin could shred or seriously weaken the bone. The difficulty of guide-pin placement can also lead a frustrated surgeon to choose a less than optimal placement, putting the patient at risk for cut-out or faulty setting of the femoral head which could lead to settling of the femoral head. U.S. Pat. No. 4,722,336 discloses a method and device to provide a three dimensional Cartesian coordinate of the target object using an x-ray or fluoroscopic imaging device and a radio-opaque targeting system. However, this method and device cannot be used where the fluoroscope cannot be aligned head-on with the guide piece and bony target. U.S. Pat. No. 4,418,422 discloses an aiming device which is attached to an x-ray source. Similarly, this device cannot be used where a fluoroscope cannot be aligned head-on with the guide piece and the bony target. This device also cannot be used where the view-finder cannot be aligned head-on. U.S. Pat. No. 4,976,713 discloses an aiming device that has a viewfinder with a radio-opaque component to align screws with anchoring holes in a centromedullar nail. This device also cannot be used where the viewfinder cannot be aligned head-on with the guide piece and bony target. A similar limitation prevents the use in such circumstances of the device disclosed in U.S. Pat. No. 4,803,976 patent, which discloses the use of parallel radio-opaque fluoroscopy target markers aligned parallel but one beside, not above, the other target marker. Presently, where a fluoroscope cannot be used aligned head-on with the guide piece and the bony target, surgeons have used visual landmarks and repeated insertion to obtain appropriate placement. This increases the surgeon's, the other medical personnel's, and the patient's exposure to x-ray radiation, increases the total operation time, and could lead to serious problems such as cut-out, as described above. There are currently no devices that are configured to be hand-held and easily used by the surgeon with an x-ray or fluoroscopic imaging device to accurately determine the proper entry point and trajectory for the insertion of an instrument, such as a pin, nail, screw, rod, wire, drill bit, or other implant. Also, there is currently no such targeting device which is adaptable and flexible to be used with different size patients which may require a targeting device to be custom adapted according to the patient's size and body shape to accurately project the proper alignment for the instrument or implant to repair the particular bony target. There has therefore been a long felt need among surgeons and other medical personnel in this field for a targeting device which would allow the surgeon to align the guide-pin in both the AP and ML positions before actually inserting the guide-pin so that the guide-pin can be inserted accurately on the first attempt with a variety of sizes and shapes of patients, particularly, but not limited to, where an x-ray or fluoroscopic imaging device cannot be aligned head-on with the guide piece and the bony target. SUMMARY OF THE INVENTION The targeting device is generally configured to be a hand-held and operated orthopedic instrument which typically has a body and an arm member. The body of the device is generally comprised of two pieces, although some embodiments have a body that is one piece. Where the body of the targeting device is comprised of generally two pieces, one piece is an angle guide and the other is a guide piece. The angle guide is toward the front portion of the body of the targeting device and during use, the angle guide is in contact with bony tissue of the patient. Although other shapes could be used, the angle guide is typically shaped with a cylindrical back portion and an angular front portion, which contacts the bony tissue. When the body of the targeting device is pressed against bony tissue of the patient, the body of the targeting device becomes oriented at an angle to the bony tissue corresponding to the angle of the front portion of the angle guide. The angle guide has a passageway which may be substantially in the center of the angle guide and is large enough so that a particular instrument or implant can be passed through it. The passageway of the angle guide corresponds to the passageway of the guide piece so that the particular instrument or implant can readily pass through the entire body of the targeting device. The guide piece and the angle guide may be connected in various ways, e.g., fixed or rotationally. A rotational connection allows the guide piece to rotate while the angle guide remains fixed in place, gripping bony tissue. With a rotational connection, the guide piece may rotate freely, by indexing, or with friction. Another benefit of the two piece body is that a custom angle guide may be used to properly align the instrument or implant by providing the proper angle to obtain the optimal orientation. Extending from near the back end of the targeting device's body is an arm member. The purpose of the arm member is to extend outside the patient between the x-ray or fluoroscopic imaging device and the bony target. At some point on the arm member is at least one relatively radio-opaque target marker. The target marker is oriented between the x-ray or fluoroscopic imaging device and the bony target to indicate the placement of the instrument or implant when inserted into the bony target through the passageway of the body of the targeting device. For example, one embodiment has two relatively radio-opaque target markers which are parallel with one target marker aligned above the other such that when the two target markers overlap, the projected image is aligned to establish a plane that is co-planar with the targeting device's passageway. The present invention is also a method of using a targeting device to predict an appropriate entry point and trajectory into bony tissue through which an instrument, such as a pin, screw, rod, nail, wire, drill bit, or other implant is inserted. By providing a targeting device to a surgeon or other user which is comprised of: a body with a passageway and an angular end capable of gripping bony tissue; and an arm member with at least one relatively radio-opaque target marker which may be imbedded within the arm member. The user can predict the placement of said instrument, such as a pin, screw, rod, nail, wire, drill bit, or other implant before drilling it into place with the use of an x-ray or fluoroscopic imaging device. By manipulating the device around the axis of the body of the targeting device, the surgeon can predict the placement of the instrument or implant from various fluoroscopic views without repeatedly placing and removing the instrument or implant itself. This method may dramatically reduce both operating and fluoroscopy time, saving time and reducing the exposure of surgeons and other medical personnel to x-ray radiation. These guides can be used with at least intramedullary interlocking nails and CHS implants and may be used in other surgeries requiring accurate implant or instrument placement relative to bony structures. In a different embodiment, the present invention comprises a separate arm member which contains at least one relatively radio-opaque targeting member. Said relatively radio-opaque targeting member can be used to establish a plane that is co-planar with the base end of the arm member and indicates the projected placement of an implant or instrument, such as a pin, rod, nail, screw, or drill bit with the use an x-ray or fluoroscopic imaging device. Such arm member may be attached to or combined with another device to deliver the implant or instrument. In another embodiment, the present invention comprises a separate angle guide with a passageway which may be used to align the placement of an instrument, such as a nail, pin, screw, rod, wire, drill bit, or other implant. The angle guide has a front portion and a rear portion. One variation has a back portion which is cylindrical in shape, and a front portion that is angled relative to a bony surface to orient a passageway which extends through the angle guide. Said angle guide may be used with other instruments to further align the placement of the instrument or implant. Said angle guide comprises a plurality of teeth which may be cut in a variety of ways. One preferred embodiment has a cylindrical cut. Said teeth may be angled inward from the sides of said angle guide toward the center of the angle guide to further grip a contoured bony tissue body, such as a femur. The present invention also includes a kit containing the various components described above. BRIEF DESCRIPTION OF THE DRAWING The above and other objects and advantages of the invention will be apparent upon consideration of the following detailed description taken in conjunction with the accompanying drawings in which like characters refer to like parts throughout and in which: FIG. 1 is a side view of a intramedullary nail within a femur where the lag screw was not inserted properly; FIG. 2 a is a flow chart depicting the current process a surgeon uses to properly insert a guide-pin across a femoral neck fracture into the femoral head; FIG. 2 b is a flow chart depicting the process a surgeon uses to properly insert a guide-pin across a femoral neck fracture into the femoral head according to the present invention; FIG. 3 a is a perspective view of a fractured femur and femoral head from the anterior-posterior (AP) position; FIG. 3 b is a perspective view of a fractured femur and femoral head from the medial-lateral (ML) position; FIG. 4 a is a perspective view of one preferred embodiment of the fully assembled targeting device for use with compression hip screws with a single arm member, two radio-opaque target markers, one style of angle guide; and a guide piece; FIG. 4 b is a perspective view of an alternate preferred embodiment of the fully assembled targeting device for use with compression hip screws with a different style angle guide; FIG. 4 c is a perspective view of an alternate embodiment of the fully assembled targeting device for use with compression hip screws having two arm members, each with two radio-opaque target markers, the arm members being displaced from each other; FIG. 4 d is a perspective view of a simulated fluoroscopic image from the AP perspective and with the radio-opaque target markers aligned; FIG. 5 a is a perspective view of an alternate preferred embodiment of the fully assembled targeting device for use with intramedullary nails; FIG. 5 b is a perspective view of an alternate preferred embodiment of the fully assembled targeting device for use with intramedullary nails as oriented during use with proximal portion of a femoral bone; FIG. 6 a is a perspective view of a preferred embodiment of an angle guide which can be used to position a targeting device to a bone to prevent unintentional movement of the device while allowing for intentional movement of the device; FIG. 6 b is a different perspective view of the preferred embodiment of an angle guide which can be used to position a targeting device to a bone to prevent unintentional movement of the device while allowing for intentional movement of the device; FIG. 6 c is a perspective view of another preferred embodiment of an angle guide which can be used to position a targeting device to a bone and which includes an opening through which a means to secure the angle guide to the bony tissue can be inserted; and FIG. 7 is a perspective view of an arm member with two radio-opaque target markers which can be used in determining an appropriate entry point and trajectory for an instrument or implant, such as a pin, rod, screw, nail, wire, or drill bit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings of the targeting device 10 of the present invention, targeting device 10 is comprised of several integrated components. These components are illustrated and described with regard to FIGS. 4 a - 4 c , which show the completely assembled device, an alternate embodiment of the invention for use with intramedullary screws is shown in FIGS. 5 a - 5 b. Turning initially to FIGS. 4 a - 4 c there is shown arm member 12 for targeting device 10 . In a preferred embodiment arm member 12 is comprised of a plurality of separate elements which, upon being assembled as described below, form arm member 12 adapted for providing targeting for targeting device 10 . The benefit of forming targeting device 10 from a plurality of separate, interconnected elements is that the dimensions of targeting device 10 may thereby be varied as necessary by substituting various sizes and variations of elements to conform to the size and shape of a particular area of a particular patient's body. In an alternate embodiment, however, it is further contemplated that targeting device 10 may be formed, e.g., molded, as a unitary construct containing only a single, or a limited number of structured elements. In the preferred embodiment, targeting device 10 may be formed from, for example, various length arms 12 , various sizes and shapes of angle guides 16 , various styles of guide pieces 14 , and various types of radio-opaque target markers 18 . Arm member 12 may be preferably formed from Raydel™ but may also use alternate materials, i.e., other than Raydel™, including plastics, glasses (e.g., fiberglass), metals and even wood, as long as such materials are capable of supporting targeting device 10 . Arm member 12 can be different lengths to accommodate targeting for different sizes of femurs 2 or other bony tissue and can either be fixed to guide piece 14 or may be removable so that difference lengths or styles can be interchanged. Arm member 12 extends from base 40 to end 42 . The preferred embodiment of arm member 12 has a rectangular section removed proximal end 42 of arm member 12 creating a rectangular gap at the end 42 of arm member 12 . The removal of this rectangular section makes the relatively radio-opaque target markers 18 show more distinct by x-ray or fluoroscopic imaging device. This portion may be small or could extend the length of arm member 12 . The gap may also be various other shapes so as to allow an enhanced view of the relatively radio-opaque target marker 18 . Similarly, target markers 18 may be small or could extend the entire length of arm member 12 . An alternative embodiment of arm member 12 comprises only the two target markers 18 essentially extending from guide piece 14 . Another embodiment of targeting device 10 includes two or more arms 12 displaced from each other. (See FIG. 4 c ). Where targeting device 10 has two arms displaced from each other, e.g. by 90° so that one arm member 12 is in the AP position while the other arm member 12 is simultaneously in the ML position. (See FIG. 4 c ). Angle guides 16 are preferably formed from some metal such as stainless steel or aluminum, however, the material used to form this component is only limited in that it should be a material that is hard enough to grip the bone tissue and to maintain its passageway, for example, various plastics could be used. Angle guides 16 can vary by the type and the cut of teeth 20 that are used. For example, a preferred embodiment of angle guide 16 has a small number, of inwardly angled, cylindrically cut teeth 20 to grip femur 2 when using targeting device 10 . Alternatively, angle guide 16 could have more teeth and a different cut. Angle guide 16 can be made with many different angles and is easily interchangeable so that the targeting device 10 can be custom fit to the particular femur 2 . Another embodiment includes a quick release connection to facilitate the exchange of angle guides 16 . Angle guide 16 is connected to guide piece 14 . Guide piece 14 is preferably made of the same material as arm member 12 . Guide passageway 22 aligns and extends through both guide piece 14 and angle guide 16 and can be of varying sizes to accommodate different size pins, screws, nails, wires, or drill bits. Another embodiment of angle guide 16 contains a recessed pin that the surgeon can extend with a button or switch to secure angle guide 16 to femur 2 for increased stability. A further embodiment of angle guide 16 is secured to the femur 2 through the use of a vacuum, clamp or strap. Another embodiment of angle guide 16 contains an opening to drill a screw or pin through to secure angle guide 16 to femur 2 . Another embodiment employs a simple clamping device which secures angle guide 16 to femur 2 . The relationship between the guide piece 14 and arm member 12 can be fixed or rotational. A preferred embodiment has a guide piece 14 which rotates at least from the AP orientation to the ML orientation, rotating arm member 12 accordingly, while the angle guide 16 remains fixed on femur 2 . Another embodiment has a guide piece 14 with an indexing rotation which may correlate to a particular number of degrees of rotation relative to the angle guide 16 which remains fixed on femur 2 . Another embodiment may have a friction fit between guide piece 14 and angle guide 16 , to prevent arm member 12 from freely swinging without a minimal amount of force. Yet another embodiment has a guide piece 14 with a variable friction setting to increase and decrease the friction resistance when rotating the guide piece 14 relative to the fixed angle guide 16 . Another embodiment of guide piece 14 has a lock-out feature so that when target markers 18 of arm member 12 are aligned in the AP position, the lock-out feature can be enacted and the guide piece 14 will turn to the ML position and stop or lock in that position. FIG. 4 d shows a fluoroscopic image of targeting device 10 from the AP perspective over femur 2 and, in particular, femoral head 4 . Radio-opaque target markers 18 are aligned so that only first marker 18 appears with second marker 18 co-planar to first marker 18 . These aligned target markers 18 are then co-planar with a beam from an x-ray or fluoroscopic imaging device and a desired location or trajectory relative to a bony target, such as femoral head 4 . These aligned target markers 18 are also co-planar with passageway 22 . The superimposed position of aligned target markers 18 indicates where the guide-pin will insert into femoral head 4 through passageway 22 . In addition to this view, a surgeon will also align target markers 18 in the ML position to ensure that the guide-pin will insert into the middle of femoral head 4 . This is done by turning or rotating arm member 12 orthogonally from the AP position to the ML orientation and moving the x-ray or fluoroscopic imaging device so that it is also oriented in the ML position. Arm member 12 is then moved until target markers 18 overlap and appear as one marker 18 . When target markers 18 overlap, the positioning of the superimposed target markers 18 indicates the position of the guide-pin if inserted into the femoral head 4 . A surgeon may easily align target markers 18 in the AP position and then the ML position and have a certainty that the guide-pin will be in the appropriate position in the femoral head 4 without having to iteratively remove and reinsert the guide-pin until satisfactory positioning is achieved. Radio-opaque target markers 18 may be made from any relatively radio-opaque material. In a preferred embodiment, stainless steel wires are used as target markers 18 . Other embodiments may use tantalum, gold, or other high atomic number metals. Alternatively, a contrast coating such as barium sulfate may be used to coat portions of arm member 12 to substitute for or to enhance target markers 18 . Other possible radio-opaque materials will be obvious to one skilled in the art. Target markers 18 may be of various shapes and configurations so that when aligned co-planar with passageway 22 , target markers 18 provide some indication of alignment. Target marker 18 may be substantially one dimensional, such as a wire, substantially two dimensional such as a triangle, or three dimensional. Examples of such target markers 18 include: two wires which overlap when co-planar with passageway 22 ; two sets of wire segments which appear separate with gaps between segments when not co-planar with passageway 22 , however, appear as one solid line when co-planar with passageway; two wires, one of which is larger than the other to indicate the direction to rotate arm member 12 to be co-planar with passageway 22 ; one two dimensional target marker 18 , e.g. triangular, circular, trapezoidal, which appears one dimensional when co-planar with passageway 22 . FIGS. 5 a and 5 b pertain to an embodiment of the present invention that can be used with an intramedullary nail. The device 110 is comprised of several components. Component 100 in FIG. 5 b is a standard intramedullary alignment device which is well known in the art and is described in U.S. Pat. No. 5,334,192 to Behrens. This alignment device attaches to the intramedullary nail to assist in determining the proper point and trajectory of insertion. Device 110 fits onto component 100 to allow the alignment of the lag screw after the intramedullary nail is inserted into femur 2 . This is done similarly to targeting device 10 where the surgeon orients device 110 in the AP position so that markers 118 align. The x-ray or fluoroscopic imaging device is moved to the ML position and arm 112 is also moved so that markers 118 align. This will orient the guide-pin so that it may be inserted through guide 114 , through the proximal opening on the intramedullary nail and into femoral head 4 . The components of device 110 may be varied similarly to that of the corresponding components of targeting device 10 . In a preferred embodiment, arm 112 is attached to guide 114 for rotation therewith by a standard spring clip 140 . Arm 112 can then be rotated from the AP plane to the ML plane by rotating guide 114 . Another object of the present invention is to provide a method of aligning an orthopedic instrument or implant with bony tissue using an x-ray or fluoroscopic imaging device. This is done by providing a passageway 22 through guide piece 14 and angle guide 16 , through which the instrument implant such as a pin, screw, nail, wire, or drill bit is passed, and further providing at least one targeting device, such as arm member 12 , fixed to said guide piece 14 and containing at least one relatively radio-opaque target marker 18 that establishes a plane that is co-planar with an axis of said passageway 22 . The targeting device is then manipulated until the plane established by the targeting device is co-planar with a beam from an x-ray imaging device and a desired location or trajectory relative to a bony target in at least one view and passing said instrument or implant through said guide passageway 22 . In another method, said targeting device rotates about the passageway 22 axis. FIGS. 6 a - 6 c show another embodiment of the present invention which is angle guide 216 which can be used to assist in the positioning of the insertion of an instrument, such as a nail, pin, rod, screw, wire, drill bit, or other implant into a bony target. Angle guide 216 may have a plurality of teeth 220 which are attached along the front portion of angle guide 216 . Teeth 220 may be a cylindrical cut or other cut to allow for angle guide 216 to grip the bony surface without unintentional movement or sliding of angle guide 216 . At the same time, teeth 220 allow the user to intentionally move or adjust the position of angle guide 216 to achieve the best alignment. FIG. 6 c shows an embodiment of angle guide 216 with opening 250 through which an attachment means may be inserted to further secure the angle guide 216 to a bony surface. The attachment means may be a vacuum tube, a securing pin, or a screw. Alternatively, a simple strap or clamp may also be used to secure angle guide 216 . This means of securing the angle guide 216 would further guard against incidental movement of the targeting device. Such movement may require the removal of the vacuum, strap or clamp securing angle guide 216 or the retraction of a securing pin or screw. Teeth 220 may extend straight across the front face of angle guide 216 or may angle inwardly or even outwardly. A preferred embodiment angles teeth 220 in from each side 224 of angle guide 216 to center line 226 . Angle guide 216 may be formed with the front portion 228 extending toward the back portion 230 along sides 224 at any angle from 0° to 90°. Also, the angle may be fixed or variable from front portion 228 to back portion 230 . FIG. 7 shows another embodiment of the present invention which is an arm 212 which can be used to assist a surgeon or other medical personnel with the determination of the proper insertion point for an instrument or implant, such as a nail, pin, rod, screw, or drill bit. Arm 212 may be fixed or attached in some manner to a device at base 240 or used alone in some manner. Arm 212 may have a rectangular piece cut from arm 212 which is relatively small or relatively large proximal end 242 . Arm 212 may be comprised of a small body made of Raydel™, or some substitute material as described above, with long or short target markers 218 which extend from the body of arm 212 . Target markers 218 may be some relatively radio-opaque material such as stainless steel, tantalum, or a high atomic number metal. Alternatively, target markers 218 may be some contrast, such as but not limited to barium sulfate, painted or otherwise interposed on arm 212 . The present invention also includes a kit which may contain all components or a variety of the components mentioned above. One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for the purpose of illustration only and not of limitation. The present invention is therefore only limited by the following appended claims. All references cited herein are hereby incorporated by reference.	A hand instrument and method for use by a surgeon to target the appropriate entry point and trajectory on bony tissue through which an instrument, such as a nail, pin, screw, rod, wire, drill bit, or other implant is passed. Imbedded within the instrument is at least one relatively radio-opaque target which allows the user to predict with the use of an x-ray or fluoroscopic imaging device the placement of said instrument or implant before drilling it into place with the use of an x-ray or fluoroscopic imaging device. By manipulating the device around the axis of the guide piece, the surgeon can predict the placement of the instrument or implant without iterative insertion and removal of the instrument or implant itself.	0
BACKGROUND OF THE INVENTION The present innovation relates generally to wireless networks and, more specifically to a protocol for aggregating multiple radio interfaces into a single logical bridge interface. Local Area Networks (LANs) are widely used to provide interconnectivity between computers affiliated with a building or site. Typically, LAN's consist of multiple computers connected together by a hardwired network or system backbone. For example, a typical system backbone is an Ethernet or Token Ring based system. A server or host computer will also be connected to the backbone and serve as a central controller for the particular LAN. Multiple LAN segments are interconnected by devices called “bridges” or “switches”. Advances in technology have enabled LAN's to be used to interconnect wireless devices, such as laptop computers, personal data assistants and even Voice-over-Internet-Protocol telephones. In wireless networks, access points are connected to the LAN and provide for wireless interfacing of such portable wireless devices to the backbone. Although connecting several computers or portable devices within a single building can readily be accomplished via the use of a LAN infrastructure, difficulties often arise when more than one building or site, needing connection to the infrastructure, are involved. In such cases, it may be desirable to have a single host computer or server provide all buildings or sites with interconnected services such as e-mail and group directories. In order to use a single server and enable communication between each building or site, some manner of interconnecting each LAN is needed. One known method of interconnecting each LAN associated with a specified area is to physically make an additional hard wired connection between each LAN. Unfortunately, this method is expensive, time consuming and sometimes even not feasible. For example, a physical connection between buildings may not be possible when buildings are several miles apart or separated by natural obstacles (e.g. rivers, streams). As a result, wireless bridges have been developed in order to provide a method of connecting two or more LANs. Bridges connect either wired or wireless networks with a physical gap between them. Wireless bridges normally offer point-to-point or point-to-multipoint connectivity for up to (approximately) 15 miles. Stated another way, a wireless bridge is a device which is physically connected to the LAN and can wirelessly transmit and receive data and other communications from other bridges connected to different LAN's. Thus, a wireless bridge allows several LAN's to become interconnected without the need for a physical connection between LANs. In accordance with conventional wireless networks, prior implementations of network bridges support single IEEE 802.11 radio interfaces. However, because these conventional bridges operate on a single public band radio link, they are susceptible to outages due to a variety of conditions (e.g. interference). Because conventional switches correspond to a single radio link, the corresponding data rate is greatly impacted by the limitations of the single radio link. As well, in accordance with traditional implementations, Spanning-Tree Protocol (STP) recalculation is required to activate redundant radio links. By way of background, STP is a link management protocol that provides path redundancy while preventing undesirable loops in the network. For an Ethernet network to function properly, only one active path can exist between two LAN segments. Multiple active paths between LAN segments cause loops in the network that may result in rapid frame duplication and “network storms”. To provide path redundancy, STP defines a tree data structure that spans all switches in an extended network. STP forces certain redundant data paths into a standby (blocked) state. If one network segment in the STP becomes unreachable, or if STP costs change, the spanning-tree algorithm reconfigures the spanning-tree topology and reestablishes the link by activating the standby path. STP operation is transparent to end stations, which are unaware whether they are connected to a single LAN segment or a switched LAN of multiple segments. While transparent to end stations, the STP recalculation, or reconfiguration, makes recovery from a failed conventional wireless bridge cumbersome, slow and costly. Further, traditional wireless bridge products do not leverage or utilize catalyst switch (e.g. software/firmware/ASIC) logic. What is needed in the art is a system and method for increasing the reliability and cost effectiveness of bridging systems as applied to wireless network applications. Further, what is needed is a system and method that uses known protocols (e.g. port aggregation protocol (PAgP)) to aggregate multiple radio interfaces into a single logical bridge interface thereby enhancing reliability and cost effectiveness. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a system and method for aggregating multiple radio interfaces into a single logical bridge interface. Further in accordance with the present invention, there is provided a system for wireless bridging between networks. The system comprises one or more master switches, wherein each master switch includes an associated plurality of master switch wireless modules, each master switch wireless module including means for selectively broadcasting an associated connection signal. The system further comprises a master switch aggregation port, associated with the master switch, which is in data communication with each of the plurality of master switch wireless modules. The master switch aggregation port includes means for selectively routing data among the plurality of master switch wireless modules. The system also comprises one or more slave switches, wherein each slave switch includes an associated plurality of slave switch wireless modules. Each of the plurality of slave switch wireless modules includes means for receiving one associated connection signal and means for establishing a wireless data communication link with a master switch broadcasting the associated connection signal after receipt by the slave switch. Furthermore, the system also comprises a slave switch aggregation port associated with the slave switch. This slave switch aggregation port is in data communication with each of the plurality of slave switch wireless modules. The slave switch aggregation port includes means for selectively routing data among the plurality of slave switch wireless modules. Still further in accordance with the present invention, there is provided a method of wireless bridging between networks. The method includes the step of selectively routing data among a plurality of master switch wireless modules, associated with a master switch, via a switch aggregation port. The method then progresses to selectively broadcasting a connection signal from each of the plurality of master switch wireless modules. Next, the method proceeds to receiving one associated connection signal into each of a plurality of slave switch wireless modules associated with a slave switch. Then, the method continues to the step of establishing at least one wireless data communication link between master switch modules broadcasting the associated connection signal and an associated one of the plurality of slave switch wireless modules after receipt of the connection signals. The method progresses further to the step of selectively routing data among the plurality of slave switch wireless modules via a slave switch aggregation port associated therewith. In one embodiment of the present invention, the method further includes the steps of sensing a loss of at least one connection signal, and selectively redirecting data among at least one a) the master switch wireless modules and b) the slave switch wireless modules in accordance with a sensed lost connection signal. Still other objects of the present invention will become readily apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the best modes best suited for to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modifications in various obvious aspects all without from the invention. Accordingly, the drawing and descriptions will be regarded as illustrative in nature and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS The subject invention is described with reference to certain parts, and arrangements to parts, which are evidenced in conjunction with the associated drawings, which form a part hereof and not, for the purposes of limiting the same in which: FIG. 1 illustrates a network architectural diagram that illustrates representative network components and corresponding links in accordance with a disclosed embodiment; FIG. 2 illustrates a flow chart of the methodology outlining the process steps to generate and establish “link-up” and/or “link-down” events in accordance with a disclosed embodiment; and FIG. 3 illustrates a flow chart of the methodology outlining the process steps to establish and remove inter-switch point-to-point and/or point-to-multipoint links in accordance with a disclosed embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following includes examples of various embodiments and/or forms of components that fall within the scope of the present system that may be used for implementation. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than limitations, of the present invention. Although the embodiments of present system and method described herein are directed toward an IEEE 802.11 wireless network, it will be appreciated by one skilled in the art that the present concepts and innovations described herein are applicable to alternate wired and wireless networks and network protocols, without departing from the spirit and scope of the present innovation. By way of background, to establish a radio link or interface, an Ethernet switch communicates with an attached Radio Module (RM) over a logical Control Link and a logical Ethernet Link. Multiple logical Ethernet links and corresponding wireless (e.g. 802.11) links are aggregated using a port aggregation protocol (e.g. PAgP) to form a single “logical bridge interface.” The aggregation enables the diversion of traffic in the event that a member link (i.e. logical Ethernet link) in an aggregated bundle is-lost or fails. It will be appreciated that the link aggregation also increases the bandwidth and reliability of wireless (e.g. 802.11) bridge links. It will further be appreciated that wireless links may be separated by frequency or spatial diversity. As well, low-level point-to-point or point-to-multipoint radio links may be dynamically established in accordance with the subject protocol. In other words, multiple radio links are aggregated into a single logical bridge interface using a port aggregation protocol. For example, PAgP may be used in accordance with the present system in order to establish a single logical bridge interface. Radio links, upon establishment, are added to the aggregated bridge interface. Radio modules (RMs) (e.g. IEEE 802.11 RMs) are attached to a wireless-enabled communications link. For exemplary purposes, the embodiments discussed herein are directed toward a Wireless-enabled Ethernet (WE) switch via an Ethernet link. Of course, alternate switches may be used with alternate LAN architectures without departing from the spirit and scope of the embodiments described herein. After connecting, Ethernet frames are bridged over an IEEE 802.11 link between an RM in a first switch and an RM in a second switch. An RM operates in “master mode” or “slave mode.” Accordingly, a “master” RM may be configured to send periodic beacons while a “slave” RM scans for the beacons. This exchange prompts the communication link between the RMs. Turning now to FIG. 1 , an exemplary architecture 100 is shown. As shown in FIG. 1 , eight (8) RMs 101 - 108 attached to two (2) Ethernet switches 110 , 115 on physical Ethernet ports 121 - 128 are shown. WE switches 110 and 115 are configured with Logical Control Links, shown in FIG. 1 as reference numbers 1011 , 1021 , 1031 , 1041 , 1051 , 1061 , 1071 , and 1081 , and Logical Ethernet Links, represented by reference numbers 1012 , 1022 , 1032 , 1042 , 1052 , 1062 , 1072 , and 1082 , corresponding to each RM 101 - 108 . Each RM-specific Logical Control Link and Logical Ethernet Link are multiplexed onto a single physical Ethernet link. It will be appreciated that messages used for RM management and link statusing are sent over the Logical Control Links 1011 , 1021 , 1031 , 1041 , 1051 , 1061 , 1071 , and 1081 . The Logical Ethernet Links 1012 , 1022 , 1032 , 1042 , 1052 , 1062 , 1072 , and 1082 bridge Ethernet frames between RMs 101 - 108 . It will further be appreciated to one skilled in the art that a header, pre-pended to frames sent via a physical Ethernet link is used to distinguish between control and data frames. A logical Ethernet link is represented by an internal logical Ethernet interface 131 - 138 within a corresponding WE switch 110 or 115 . RMs are relatively simple devices in comparison to traditional 802.11 bridges. The establishment and aggregation of logical Ethernet interfaces 131 - 138 are enabled by bridging and forwarding logic (e.g. 802.1D, PVST, source-learning) contained within WE switches 110 and 115 . The RMs 101 - 108 are physically separated from the WE switches 110 and 115 via physical Ethernet links in order to improve sensitivity. It will be appreciated that the associated RMs may be desensitized if multiple RMs, in the same radio frequency (RF) band, are contained within the same switch, even if the antennas are separated. Further, an artisan will appreciate that the radio links are isolated by “spatial separation” or “frequency separation.” As illustrated in FIG. 1 , each WE switch 110 and 115 contains an RM Control Entity 141 - 148 corresponding to each attached RM 101 - 108 respectively. In operation, each RM Control Entity 141 - 148 sends commands and receives status information over a single logical Bridge interface from its corresponding RM 101 - 108 . Eight (8) RMs 101 - 108 are attached to two (2) Ethernet switches 110 and 115 on physical Ethernet ports. In accordance with the example, a switch has a logical RM Control Link 1011 , 1021 , 1031 , 1041 , 1051 , 1061 , 1071 , and 1081 and a Logical Ethernet Link 1012 , 1022 , 1032 , 1042 , 1052 , 1062 , 1072 , and 1082 corresponding to each attached RM 101 - 108 , respectively. Each Logical Ethernet Link/Control Link pair may be multiplexed onto a single physical Ethernet link as shown. The Logical Ethernet Interfaces 131 , 132 , 133 , 134 , 135 , 136 , 137 , and 138 corresponding to the four (4) 802.11 links from RM 1 101 to RM 2 102 , RM 3 103 to RM 4 104 , RM 5 105 to RM 6 106 , and RM 7 107 to RM 8 108 , are aggregated in Switch 1 110 and Switch 2 115 to form a single Logical Bridge Interface 150 between Switch 1110 and Switch 2115 . The set of member links or Logical Ethernet Interfaces 131 , 132 , 133 , 134 , 135 , 136 , 137 , and 138 associated with the logical bridge interface 150 are referred to as an aggregation bundle. It will be understood by those skilled in the art that any known aggregation method may be used to combine member links into an aggregation bundle. For example, it will be appreciated that aggregation protocols, such as PAgP, 802.3ad or the like, function to aggregate the member links into an aggregation bundle. The logical bridge interface 150 , comprised of an aggregation bundle, appears as a single bridge interface to the Spanning Tree Protocol (STP) in the WE switches 110 and 115 . An artisan will appreciate that an STP (e.g. 802.1D protocol) is used to prevent multiple bridge links between any two LAN segments. In operation, if a Logical Bridge Interface 150 is in an STP forwarding state, the aggregation protocol (e.g. PAgP) will distribute transmit frames to established member links. It will be appreciated that the PAgP hashes the MAC addresses of a transmit frame to determine the appropriate output member link. Therefore, in accordance with the present system and method, all traffic corresponding to a single traffic stream may be directed to a common member link. Further, in the event that a single member link (e.g. 135 ) goes down or fails, traffic is immediately diverted to other alternate member links (e.g. 131 , 133 ). The redirection of traffic in the event of a link failure is discussed in more detail below with reference to FIG. 2 . Now with reference to FIG. 1 and FIG. 2 together, the RMs 101 - 108 provide link status information to their corresponding RM Control Entity 141 - 148 . Accordingly, the RM Control Entities 141 - 148 generate the “link up” or “link down” events described below. It will be appreciated that the designations “link up” and “link down” are provided for discussion purposes only and are intended to describe physical and/or logical connection states of the RMs. Referring now to FIG. 2 , there is illustrated a flow chart of an embodiment of the methodology 200 for generating and establishing “link up” and/or “link down” RM events. Initially, at step 210 , the system establishes a radio link in accordance with the applicable protocols and standards described above and those known in the art (e.g. IEEE 802.11). Next, the system determines at step 220 if a valid radio link is established. Upon a determination at step 220 that a valid radio link has not been established, the system returns to step 210 and again attempts to establish the radio link. When the system determines at step 220 that a valid radio link has been established, the system notifies the corresponding RM Control Entity at step 230 . For example, an RM 105 in a first switch 110 notifies the corresponding RM Control Entity 145 when a radio link is established to a peer RM 106 in a second switch 115 . Upon receiving notification, the RM Control Entity generates a “link up” event for the respective Logical Ethernet Link at step 240 . After receiving notification from the RM 105 , the Control Entity 145 generates a “link up” event for the respective Logical Ethernet Link 135 to be linked up into the Logical Bridge Interface 150 . Next, the system determines whether or not the link has failed at step 250 . When the link remains functional, as determined at step 250 , the system remains idle in the “linked up” state and continues to query as shown. On the other hand, if at step 250 , a determination is made that the link has failed, the corresponding Control Entity will be notified of the failure at step 260 . Therefore the RM 105 notifies the corresponding Control Entity 145 in the WE switch 110 that the radio link 160 to the peer RM 106 has failed. When such a failure has occurred, the system generates a “link down” event to disconnect the Logical Ethernet Link at step 270 . In other words, the RM Control Entity 145 generates a “link down” event for the respective Logical Ethernet Link 135 to prompt the switch to immediately deactivate the corresponding WE switch port 125 thereby diverting traffic to an alternate member link or port 121 or 123 , in the aggregation bundle, as shown at step 280 . Thereafter, RM 5 105 and RM 6 106 notify their respective RM Control Entities 145 and 146 in Switch 1110 and Switch 2115 that the 802.11 link 160 from RM 5 105 to RM 6 106 has failed. In response, the respective Logical Ethernet Links 135 and 136 are deactivated in Switch 1 and Switch 2 . Next, in the event that a logical bridge interface in one WE switch is blocked by the STP, the corresponding logical bridge interface in the peer WE switch must also be blocked. In operation, if Logical Bridge Interface 150 of WE switch 115 is blocked by the STP, a control message is sent over the logical bridge interface to notify the WE switch 110 that the remote end of the logical link is in a “blocked” STP state. It will be appreciated by those skilled in the art that the STP cannot block individual member links in the aggregation bundled. The STP puts the entire logical interface 150 of WE switch 115 into a “blocked” or “forwarding” state. In an alternate embodiment of the present system and method, the system determines the available bandwidth on the 802.11 member link which varies significantly due to sporadic interference and channel contention. In such cases, an RM Control Entity forwards flow control information to the respective PAgP entity in the WE switch to prompt the redistribution of traffic to bundle member links in proportion to the available 802.11 bandwidth on each link. It will be appreciated that wireless protocol and standards (e.g. 802.3ad) defines a marking protocol that is used to avoid reordering of frames when traffic is diverted. Now with reference to FIG. 3 , the system is configured to establish inter-switch point-to-point and/or point-to-multipoint RM links. Referring now to FIG. 3 , there is illustrated a flow chart of an embodiment of the methodology 300 for establishing inter-switch point-to-point and/or point-to-multipoint links. Initially, at step 310 , a “master” switch is configured with a master switch identification (ID) and a service set identifier (SSID). It will be appreciated that a master switch is a switch that is in communication with the primary backbone network. Accordingly, at step 320 , a “slave” switch is configured with a slave switch ID and SSID. It will be appreciated that the set of master and slave RMs that form a single, logical bridge link must be contained in a single master switch and a single slave switch, respectively, to avoid inter-switch link statusing. To support point-to-multipoint links, a single master RM supports wireless links to multiple slave RMs; however, each slave RM must be in a different slave switch. Stated differently, two or more RMs in the same slave switch cannot establish a link with the same RM module in a master switch. After configuring the SSID of the master and slave switches, the system proceeds to classify the associated RMs as either masters or slaves. As shown in FIG. 3 , the RMs associated with the master switch are classified as “master” RMs at step 330 , and the RMs associated with the slave switch are classified as “slave” RMs at step 340 . Therefore, at block 330 , the RMs on a master switch are configured in master mode thereby designating the RMs as master RMs. Likewise, RMs on a slave switch are configured in slave mode thereby designating the RMs as slave RMs at step 340 . It will be appreciated that each RM is configured with an RM Interface ID to uniquely identify the RM. In other words, a master RM may only establish a radio link with a slave RM which has a matching SSID. In the preferred embodiment, the SSID is a standard 802.11 SSID, the Switch ID is an 802.1D Bridge Address and the RM Interface ID is an 802.11 BSSID. Of course, any preferred identifiers may be used in accordance with the present system and method without departing from the spirit and scope of the subject invention. Following configuration of the master RMs and slave RMs, at step 350 each master RM generates periodic beacons which contain the SSID, the master Switch ID and the RM Interface ID. An artisan will appreciate that the master RM transmits beacons on a single radio channel. It should be noted that a set of master RMs in switches that are wired to the primary backbone network must advertise availability to slave RMs attached to secondary Ethernet LANs. This advertising is accomplished via generation and transmission of the beacons at step 350 . The beacons include the Switch ID and SSID, configured for the respective master switch, and the RM Interface ID configured for the respective RM. In order to effectuate the linking of RMs, at step 360 an unattached slave RM scans available radio channels for the beacons sent by master RMs. Specifically, an unattached or unbound slave RM, attached to a slave switch, scans for beacons from a master RM, in a master switch having a matching SSID, which is not currently bound to a different slave RM in the same switch. Upon detecting a master beacon, the slave determines at step 370 if the master RM has a pre-established link to a slave in the same switch as the subject slave switch. When the selected master RM has a pre-established link to a slave in the same switch as determined at step 370 , the system returns the slave to scan for additional master beacons as shown at step 360 . When a pre-established link is not present, as determined at step 370 , the master and slave dynamically link forming a Bridge Interface at step 380 . In other words, an unbound slave RM will select a master RM if the master RM has a matching SSID and the master RM has not yet established a link to another slave RM in the same slave switch. It will be appreciated by those skilled in the art that the SSIDs and other identifiers of the respective master and slave RMs are compared for compatibility. The slave RM reports its slave Switch ID and Interface ID in an association or re-association message sent to the master RM to establish a wireless link. After a first slave RM, in a slave switch, has established a link with a first master RM, in a master switch as shown at step 380 , other slave RMs in the same slave switch must establish links with other master RMs in the same master switch, to avoid operating the port aggregation protocol across multiple switches. As each RM-to-RM link is established, the RM Interface ID of the respective master RM is added to-a set of prohibited Interfaces IDs at step 385 . A slave RM cannot establish a link with a master RM, if the master RM's Interface ID is in the set of prohibited Interface IDs. Therefore, after a first slave RM has established a link with a first master RM, other slave RMs, in the same slave switch, only scan for master RMs that have the same Switch ID as the first RM as shown at step 390 . At this point, a Bridge Interface is created for each master/slave pair both in the master switch and in the slave switch. Upon the establishment of a master/slave radio link as described with respect to FIG. 2 , the corresponding logical Ethernet interface is added to the aggregated Bridge Interface for the master/slave switch pair as previously described. As described, an aggregation bridge interface includes a set of master RM to slave RM links whereby all master RMs are in a single master switch and all peer slave RMs are in a single slave switch. In alternate embodiments, a single master RM is linked to multiple slave RMs so long as the multiple slave RMs are located in distinct slave switches. Thus, a logical Ethernet interface is associated in the master switch corresponding to each of the master RM's links to a slave RM. An artisan will appreciate that a low-level protocol is used to establish an “optimal” logical master/slave switch logical bridge link. For example, a slave switch contains RMs configured to connect with master RMs in multiple master switches. The “optimal” logical bridge link is the aggregated link with the lowest “cost.” It will be appreciated that the cost of an aggregated logical bridge link decreases as RM-to-RM links are added or as the bandwidth of existing RM-to-RM links increases. Further, the cost increases if RM-to-RM links are lost of if bandwidth is lost. Accordingly, in order to optimize link costs, the slave RMs in a single slave switch will advantageously select master RMs, which reduces the aggregate link cost. Sporadic changes in aggregated link cost are hidden from the higher-level STP in order to avoid frequent STP topology changes. A master switch, with a point-to-multipoint link to multiple slave switches, must distribute a copy of a frame to each slave switch if the frame has a multicast destination address or an “unknown” unicast destination address. A master switch may send a separate copy to each slave switch or it may multicast a single copy to multiple slave switches. A master switch may use a “reliable multicast transmission protocol” to reliably deliver multicast frames to multiple slave switches. While the present system has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the system, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept. Although the preferred embodiment has been described in detail, it should be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.	A system and method for aggregating multiple radio interfaces into a single logical bridge interface with reference to an IEEE 802.11 Wi-Fi network and an Ethernet local area network. The system includes a master switch with multiple associated wireless modules. Each master switch wireless module selectively broadcasts an associated connection signal. The master switch has an associated aggregation port, which is in data communication with each of the master switch wireless modules and selectively routes data among the master switch wireless modules. The system also includes a slave switch with multiple associated wireless modules. Each of the slave switch wireless modules receives one associated connection signal and establishes a wireless data communication link with the broadcasting master switch. The slave switch also includes an associated aggregation port, which is in data communication with each of the slave switch wireless modules, selectively routes data among the slave switch wireless modules.	7
This invention relates to heating and fuel systems intended for use primarily, but not limited thereto, on motor vehicles operating in extremely cold environments, where use and conservation of heat energy is of critical importance for heating the vehicle operator's space thereof as well as the engine fuel therefor, and separating out moisture absorbed and entrained therein, prior to use. BACKGROUND OF THE INVENTION The operation of internal combustion engines in frigid environments brings many problems resulting from the low temperatures, among which are: providing a safe and comfortable working environment for the engine operator; separating moisture from the motor fuel; obtaining an optimum mixture of fuel and air before inducting said mixture into the engine; and preventing heat loss during the foregoing operations. A safe and comfortable working environment for vehicle operators, even in frigid environments, is not normally associated with the heating of fuels and fuel/air mixtures, or the demoisturizing of fuels. However, since heat is a common factor in each function, they are considered as relevant and interrelated aspects of the same problem in the present invention. Separating moisture from fuel is important in frigid conditions. Several problems become critical, especially for engines used in motor vehicles: water absorbed or entrained in fuel can freeze, endangering the integrity of enclosures and lines; evaporation of either liquid reduces the temperature of the mixture, increasing the danger of icing; the space for accomodating insulation or for housing separator equipment is relatively limited; the problem of maintenance and repair is very great, since the environment of use is severe, in terms of vibration, extremes of temperature, etc.; the users/operators, of vehicles especially, are often mechanically and technically unsophisticated, requiring the equipment thereof to be troublefree and easy to maintain; and the proportion of overall equipment weight and cost to be allocated to heating and separator functions is usually small, since they do not represent major, or even subsidiary, engine or vehicle objectives. It is well known that heating fuel and fuel/air mixtures for use in internal combustion engines becomes critical as the environmental temperature becomes colder, because the more volatile fuels, such as gasoline or even kerosene, have a substantial cooling effect as they vaporize, causing problems with vaporization and icing. Extremely cold weather intensifies these problems. Several devices have been developed to heat fuel/air mixtures for such engines, but these ignore the fact that fuel, if it is heated, vaporizes more easily and mixes with air more efficiently. Diesel fuel, on the other hand, often needs to be heated to enable it to vaporize and mix properly with air to obtain an optimally combustible mixture. Especially is this true in extremely cold climates. Thus, solutions to these problems for engines using more volatile fuels often are not satisfactory for diesel engines. The heating of the operator's space, the heating of fuel, and the separation of moisture absorbed and entrained therein, traditionally have been dealt with as separate problems, and the following prior art survey will follow that pattern, although the present invention solves them as part of the same problem. Space heaters for motor vehicles are familiar to everyone, and little needs to be said about those that use radiator coolant as the heat source. Fuel heaters for diesel fuel are used widely. Baker U.S. Pat. No. 4,372,260 discloses an engine heater attachment for heating the fuel of an engine before introducing it into the combustion chambers. This obtains better vaporization of the fuel, with subsequent easier ignition of the fuel/air mixtuure, and reduces any tendency of the fuel lines and small openings in the fuel system to clog with ice or congealed fuel components which are often encountered in some of the extremely cold climates in which engines are required to operate. Heaters for fuel/air mixtures are common in the prior art. However, in frigid environments, these are less than satisfactory, as: fuel vaporizes more easily if heated; warmed vaporized fuel mixes more thoroughly with air, thus more easily achieving an optimum fuel/air mixture. Gagnon U.S. Pat. No. 4,399,794 discloses a carburetion system for an internal combusion engine which seeks to combine more complete vaporization of a fuel/air mixture with heating thereof. Drops of fuel are dropped onto a rotating fan, breaking them into smaller droplets, aiding in their vaporization, and helping to achieve a more complete fuel/air mixture thereby. Before this mixture goes into the manifold for distribution to the cylinders, it is drawn through a heater for heating and better vaporization and mixing. Other than disclosing a combination of the two functions, there is little relationship to the present invention, than which it is substantially less efficient. Baker is substantially more efficient than the Gagnon disclosure, as heating fuel before vaporization makes it easier to vaporize and obtain an optimum mixture with air. The problem of separating water from fuel is one aspect of the problem of separating one liquid from another, and it is intensified in frigid conditions. This has been the subject of a number of patents, of which Kay U.S. Pat. No. 3,362,534 is the most pertinent. Kay discloses an improved apparatus for separating entrained moisture from liquid fuels, wherein the fuel is passed, in laminar flow, over a roughened baffle plate. The roughened surface serves to trap droplets of moisture by surface tension, and they are drawn away by gravity against the flow of the fuel. According to the disclosure, the surface roughness must be within the limits of 100-180 RMS (millionths of an inch) for greatest efficiency. According to Kay, this improvement is substantially more efficient in separating moisture from fuel than previous methods. Both Kay and Baker disclose features which are incorporated into the present invention but which, separately or together, do not anticipate or even suggest the present invention. BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention is a novel system for: heating an engine operator enclosure (i.e., a cab); heating fuel for the engine; maintaining a desirable level of heat for each purpose under varying demands; separating entrained moisture from fuel; and reducing heat loss to the minimum during each of the foregoing operations. The system is especially effective in extremely cold climates, where operator comfort has sometimes been slighted for engine operating efficiency, and where moisture-containing fuels can cause several different and undesirable problems. In the present invention, four novel features, separately and in combination, operate to obtain the unexpected results disclosed herein: 1. processes for heating the operator space and for heating the engine fuel are inter-related in a novel way, with the first overriding the second in certain extreme conditions; 2. a surface treatment of the fuel heater/moisture separator cannister for improving the heating of the fuel significantly conserves heat energy for the operator enclosure; 3. the "roughened or scabrous surface" of Kay, which is therein claimed to effect a significant improvement in the separation of absorbed and entrained moisture from fuel, is exploited in a novel way to obtain unexpected improvements in: a. heating said fuel; and b. further increasing the efficiency of moisture separation therefrom; and 4. a further novel treatment of the physical form of separator baffle plates further increases the efficiency of heating the fuel; as will hereinafter be explained in greater detail. For the heating processes, heated fluid, which is engine coolant in most instances, is used for fuel heating before vaporization, as disclosed in Baker, and space heating, as is well-known in the art. However, the loss of heat energy from the heating fluid during fuel heating is unexpectedly minimized by a novel treatment of the fuel heating cannister, so as to conserve said heat energy for space heating, and the flow of heating fluid required to keep the operator enclosure at a desired temperature is automatically maintained during operation, even at the expense of engine efficiency (but not operation), to protect operator welfare and safety when necessary. At the same time as the fuel is being heated, partially by means disclosed by Baker, and partially by an unexpected result of means disclosed by Kay, unwanted absorbed and entrained moisture therein is separated therefrom by said means of Kay. The roughened surface thereof is used in a way not contemplated or suggested therein, to increase the efficiency of both fuel heating and moisture separation, beyond what is suggested or contemplated either by Kay or Baker or any combination of them. Further energy is saved by a novel surface treatment of the exterior surface of the fuel heater/moisture separator cannister. The present invention exploits the roughened surface of Kay by altering the degree of roughness specified therein to selectively absorb infrared radiation from the heating fluid - engine coolant - at substantially the range of temperatures encountered under normal operating conditions, that is, at 120°-200° F. or higher. Consequently, the effective heating surface of the fuel heater is significantly increased over that of Baker with no increase in physical size thereof for a given volume of fuel processed therethrough. At the same time, the moisture separating efficiency of Kay is unexpectedly and significantly increased by this novel heating of the separator baffle plates. Fuel containing absorbed and entrained moisture is passed, in a laminar flow, over a specially shaped separator baffle plate having a roughened surface thereon, somewhat similar to the roughened surface of Kay, but with the degree of roughness being selected to enhance the absorption of infrared radiation from the heating fluid. In addition, the baffle plates have formed therein parabolically-shaped depressions which provide additional heating of the fuel. The present invention is distinguished from Kay, Baker or a combination of them, in several novel ways: 1. the system of the present invention circulates heating fluid (normally coolant from the engine) and directs it through a flow diverter, which directs a thermostatically controlled adjustable proportion of the heating fluid through the cab heater as needed to maintain a safe and comfortable working environment for the operator, and the balance is diverted through the fuel heater/separator, where it warms the fuel; 2. the fuel heater/separator of the present invention includes: a. a baffle plate which has: I. a multiplicity of depressions formed therein to increase the surface area and heating capability thereof; II. a surface finish roughness thereon in which the degree of roughness is substantially one-fourth wave-length of the infra-red radiation at the temperature of the heating fluid; III. is inclined to the sidewall of the cannister at an angle between 0°; b. the bottom portion of the cannister is formed of an inner and outer shell, forming a closed space therebetween for heating fluid to circulate therethrough, heating the inner shell and consequently the fuel in contact therewith; and c. the angle between said inner and outer shells of said cannister is limited to an angle between 0°; d. the outer surface of said cannister is polished to reduce heat loss therefrom. Therefore, it is a principal object of the present invention to provide: 1. a system for both space heating and fuel heating, using heated engine coolant therefor, automatically apportioning said coolant to each use in accordance with predetermined requirements therefor; 2. a combination fuel separator and heater of increased efficiency and simplicity, providing: a. increased separation of moisture from said fuel; b. increased heating of said fuel; and c. reduced heat loss in the foregoing operations. It is a further object of the present invention to provide a system which automatically apportions heated fluid to a space heater and a fuel heater, while meeting required minimum levels of heat for each use under frigid conditions. It is an additional object of the present invention to provide a combined fuel heater and moisture separator which provides increased efficiency of both functions. It is yet a further object of the present invention to provide a separator of increased efficiency for separating moisture absorbed and entrained in fuel. It is a still further object of the present invention to provide a fuel heater of increased efficiency and effectiveness. Another object of the present invention is to reduce heat loss in frigid environments while providing the foregoing benefits. Other objects will become apparent as the present invention is described in connection with the drawings provided herewith. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the various components of the novel system of the present invention, with fluid interconnections and flow disclosed therein. FIG. 2 is a block diagram of a first fluid flow loop in the invention. FIG. 3 is a block diagram of a second fluid flow loop in the invention. FIG. 4 is an enlarged cut-away sectional view of the structure of the novel fuel heater/moisture separator of the present invention, including the novel moisture separator baffle plates contained therein. FIG. 5 is an enlarged view of the scabrous surface of the novel baffle plates of the present invention. DETAILED DESCRIPTION OF THE INVENTION Turning now to FIG. 1, we see a function and fluid flow schematic of the novel heating and moisture separation system 10 of the present invention. Source 12 of heating fluid (which, for convenience of description will be considered the engine coolant system, although it need not be) is connected by fluid connection 14 to inlet port 16 of flow diverter 18. First outlet port 20 of flow diverter 18 has first fluid connection 22 to space heater 24, which is connected by first fluid return 26 to source 12. Thus, there is a first fluid flow loop 28 from source 12 to flow deverter 18 to space heater 24 and return to source 12, as disclosed in FIG. 2. Second outlet port 30 of flow diverter 18 has second fluid connection 32 to heating fluid inlet port 34 of novel fuel heater/moisture separator 36 (hereinafter heater/separator 36), which is connected by second fluid return 38 from second outlet port 40 to source 12. The structure of heater/separator 36 is explained in greater detail hereinafter in connection with FIG. 4. Thus, there is a second fluid flow loop 42 from source 12 to flow diverter 18 to heater/separator 36 and return to source 12, as disclosed in FIG. 3. It will be seen that both first fluid flow loop 28 and second fluid flow loop 42 include flow diverter 18 as a common element thereof. Adjustable thermostatic control 44 is connected to first outlet port 20 by connection 46. Control 44 and space heater 24 will, in the preferred embodiment, be located in enclosure 48, which will normally be the operator's space, i.e., the cab of a vehicle. FIG. 4 discloses in greater detail the physical configuration and structure of heater/separator 36, including the novel baffle plates 50a and 50b of the present invention. Heater jacket 52 surrounds the lower portion of the novel heater/separator 36, creating a space 54 through which heating fluid from source 12 flows. Second fluid connection 32 brings the heating fluid to inlet port 34, which opens into space 54, and second outlet port 40 conveys the heating fluid from space 54 via second fluid return 38 to source 12. Third inlet port 56 brings into novel heater/separator 36 untreated fuel, which is induced into a laminar flow down the surface of novel baffle plates 50a and 50b. Space 58 inside heater/separator 36 is substantially filled with a fuel/moisture mixture, with moisture concentrated in the lower portion, and demoisturized fuel floating on top thereof, in the upper portion of the container. Moisture separated from the fuel is drawn off through third outlet port 60 at the bottom of heater/separator 36, and demoisturized fuel is drawn off through fourth outlet port 62 at the upper portion thereof. The separation process is described in detail hereinafter. Separator baffle plates 50a and 50b have fabricated in the outer surface thereof a multiplicity of novel parabolically-shaped depressions (protruberances on the inner surface thereof) 64a,64b . . . 64n, providing increased surface area for moisture separation thereon. Substantial portions of baffle plates 50a and 50b are located radiantly adjacent to, or surrounded by, that portion of heater/separator 36 which is encased by heater jacket 52. The entire outer surface 68 of heater/separator 36 is polished, with the unexpected result of reducing heat loss therefrom. FIG. 5 discloses the detailed surface structure of baffles 50a and 50b of novel heater/separator 36 of the present invention. The surface thereof has a roughened or "scabrous" texture, that is, it is covered with a multitude of tiny points or projections 66a,66b . . . 66n, the novel length of which is substantially equal to one-fourth wave-length of the infrared radiation emanating from the inner wall 70 of heater/separator 36. This radiation is due to the temperature difference between the wall 70 of heater separator 36, which has been warmed by the heating fluid, and the lower temperature of the fuel/moisture mixture and the baffles 50a and 50b. 120°-200° F. which is substantially the temperature range of the engine coolant, corresponds to a range in wavelength of 328 to 368 RMS (millionths of an inch). One-quarter wavelength will then be 82-92 RMS, and defines the degree of surface roughness required to accomplish the desired result. Any means of surface preparation which gives a "spiky" surface, such as sandblasting, may be used to obtain such a texture. OPERATION OF THE PRESENT INVENTION Thermostatic control 44 is set to obtain a desired degree of comfort in enclosure 48. Under normal circumstances, the requirements for heating fluid flow through space heater 24 to keep the temperature of enclosure 42 at the desired level will be only a small portion of the total capacity of heat source 12. That is, the quantity of heating fluid flowing in first fluid flow loop 28 is small relative to the capacity of heat source 12. Similarly, the capacity of heat source 12 is more than enough to supply sufficient heating fluid to heater/separator 36 so as to heat the demoisturized fuel for adequate vaporization to give efficient mixing with air before introducing the heated mixture into the combustion chambers. However, there may be times when external conditions require more heat in the enclosure 48 for operator safety or welfare, and flow diverter 18, in response to the setting of control 44, will maintain whatever flow of heating fluid is necessary to meet that need, even to the point of reducing, from its optimal level, the heating provided by heater/separator 36 to the fuel passing therethrough. However, the diversion would not be so great as to endanger the freezing of the fuel lines or other fuel-handling components of the engine. Kay '564 states that the surface roughness of the separator baffle should be "at least 100 RMS (microinches) and not over 180 RMS or the efficiency of separation drops off substantially" (Col. 3, lines 69-71, Kay). However, the present invention is based upon the discovery that: increased temperature of separator baffle plates 50a and 50b results in signficantly increased efficiency of moisture separation; altering the surface roughness of separator baffle plates 50a and 50b from that specified by Kay to substantially one-fourth wave-length of the infrared radiation from the heating fluid, significantly increases the temperature said baffle plates, thereby significantly increasing their efficiency of moisture separation; forming into the outer surface of said baffle plates parabolically-shaped depressions 66a,66b . . . 66n further increases the efficiency of moisture separation; Possible explanations of these effects are: this degree of surface roughness on the baffle plates acts selectively to absorb the heat of the engine coolant, thereby causing them to heat substantially beyond their normal temperature (which will be at the temperature of the incoming fuel). This would effectively increase the heating capability of the heater and obtain improved efficiency in vaporizing the fuel and its subsequent mixing with air. the parabolically-shaped depressions in the baffle plates act to focus the heat emanating therefrom and create tiny "hot spots" in the fuel above the surface which act as additional heat sources. Whatever the mechanisms, significantly improved fuel heating and moisture separation is obtained in extremely cold climates, where it is necessary to heat fuel to obtain more effective vaporization and mixing with air thereof to obtain more efficient combustion of the fuel/air mixture. It has been found that altering the surface roughness from that specified by Kay to substantially one-fourth wave-length of the infrared radiation at the temperatures of the heating fluid, changes the character of the interface between the separated water and the demoisturized fuel from an approximately one-quarter inch layer of a turbid fluid to a sharply defined surface between two clear liquid, all other conditions being equal. It has also been found that altering the exterior surface of heater/separator 36 from the normal finish, which is black, to a polished finish such as can be obtained with stainless steel, will alter the heat output of space heater 24 from inadequate for a comfortable level of heat in the enclosure 48, to an output which is more than satisfactory for the purpose. It will be appreciated by those skilled in the art that the individual or combined demands of space heater 24 or heater/separator 36 will normally be small compared to the fluid capacity of source 12. Normally, the setting of control 44, and thus the quantity of heating fluid demanded by space heater 24 to satisfy that setting, would have little or no effect on the amount of heating fluid diverted to heater/separator 36. However, there may be times when the safety and physical well being of the operator is endangered because of external weather conditions, and the efficiency of engine operation then becomes of little importance. That is, if a choice must be made as to whether the temperature in the cab will be allowed to go so low that the operator's extremities will be in danger of frostbite, or the engine will run at peak efficiency, operator welfare takes precedence. On the other hand, if a choice must be made as to whether the engine will run at all or the operator will be merely uncomfortable, continued running must take precedence, as operator welfare and survival may ultimately depend upon the continued operation of the engine. Of course, there will be few times when such extreme choices will have to be made. The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described, or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.	An apparatus for separating out absorbed and entrained moisture from fuel used in a motor vehicle or heating system. A baffle plate exposed to infrared radiation forms the primary functional moisture separating device.	5
BACKGROUND OF THE INVENTION The invention relates to a barrier device for the temporary blocking of a roadway or such, comprising barrier elements which by choice can be either in the main arranged flush with the surface of the roadway or can be swung out of it, whereby each barrier element is pivotable around an axle running in the main parallel to the main highway direction, said barrier element being joined to a counter-element present below or in the main below the roadway surface. Corresponding traffic barriers for the temporary blocking of free highways can comprise prism-shaped barriers extending along the breadth of the highway and which can be swung out of the highway in order to protect grounds in need of protection--e.g. public or private supply centres or power installations--against illegal or violent entry by motor vehicles or bicycles. Said barriers, which can also be termed blocking elements, are very large, maintenance intensive and when hit by a vehicle are fundamentally no longer in working order, i.e. the blocking element can no longer be sunk into the roadway. In the case of a disaster this results however in the area which is to be protected being blocked off, which is to be avoided at all costs. SUMMARY OF THE INVENTION An aim of the present invention is to design a barrier device as previously described, so that with minimum measuring of the simple blocking elements it is ensured that illegal driving on the roadway--regardless as to from which direction--can be prevented, whereby with regard to the construction and consequently functionability, a high degrees of reliability and ease of maintenance should be guaranteed. A further object of the invention is that the blocking element should only render a vehicle incapable of being driven when it has hit the barrier element, without the life of the driver being endangered. Finally in the case of maintenance and/or damage to the barrier device, it must be ensured thatthe roadway can still be driven on without any problems. In accordance with the invention the object is on the one hand solved in that the elements are posts, which, when they are in the main flush with the roadway surface, overlap and lie on each other above the axle. Here the pivot axle extends preferably in the counter-element, preferably in the area of the centre of gravity of the element and counter-element, so that little force is necessary to permit pivoting. In order to enable trouble-free pivoting of the elements, the said elements combine with a rod which is operated by a drive element such as a hydraulic cylinder, which is preferably coupled in the area of the counter-elements. Here the control of the hydraulic cylinder is so arranged that an energy store also guarantees that the barrier elements can be operated during an electricity cut, since only a 24V battery is for example necessary for the control itself. Apart from this as an alternative a hand pump can be provided to lower the barrier elements in an emergency, i.e. to pivot them on the axle extending parallel to the longitudinal direction of the highway. The sections of the barrier elements lying on top of each other, i.e. the overlapping areas, are formed by recesses--which complete each other in a complementary fashion--of the post elements allocated to each other, whereby the recesses themselves are preferably of a graduated shape. Through supporting the posts in the area above the pivot axle it is possible to achieve optimal reduction of weight, from the point of view of the roadway, so that additional construction measures are not necessary to support the barrier elements when they are flush with the roadway surface. The barrier elements themselves, and preferably also the counter-elements, consist of double-T girders with an edge length of 300 mm for example, whereby at least the flanges of the barrier elements are joined with flat bars and between these and the rails have reinforcing ribs. The height of the posts above the highway is preferably 650 mm, which ensures that the axles of vehicles hitting the barrier elements are damaged to such an extent that they are unable to drive away independantly. Posts of such a design withstand forces of 100 tons at a speed of 30 km per hour. The surfaces of the barrier elements, over which vehicles will drive when the elements are in their aligned or flush position, may advantageously be ridged or of checkered plate. At least the blocking element has an acute-angled rectangular form, whereby the free end is equipped with a rectangular-shaped recess to form a tooth. According to an independant proposal of the invention the blocking elements, together with the rod, can be set as a unit in a frame and are interchangeable, whereby the frame is equipped with a dead mould, which can be inserted in a pit present in the highway, whereby preferably the motor driving the rod can be inserted into the frame interchangeably together with the unit. By means of such a design the fitting of the barrier device is completely trouble-free. A pit has only to be excavated out of the roadway and the ground to be cast with a cement floor in order to fit the frame with the dead mould, which consists of sheet metal. This is then cemented, which guarantees a high degree of accuracy. Finally, as a unit, the barrier elements held by a supporting construction (assembly unit) can be fitted with the counter-elements as well as the rods and drive equipment, and for example in the case of maintenance work can be removed again as a unit. The frame only has to be then covered with a ramp which can be driven over, and then the roadway is clear even during maintenance work. The underground supporting construction (assembly unit) containing the elements in a pivotable fashion is hot-dip galvanised and is statically equipped in accordance with the strains to be expected. All rotating parts are provided with lubricating devices, whereby the bearings themselves are manufactured from high-quality bearing material in order to guarantee a high degree of efficiency even with extreme strain. With regard to the pivoted barrier elements it must be said that in a position pivoted out of the roadway surface at an angle of 90° they interact with a dead stop to limit the pivoting process. In the opposite direction an uncontrolled swinging back is blocked by the operating cylinder itself. This blocking action prevents the unwanted swingback of the barrier elements even in the case of an outer force being exerted, either vertically or horizontally. In an embodiment of the invention braces can emanate from the lateral surfaces at right angles and extend in the direction of the neighbouring post, thus guaranteeing that bicycles for example cannot pass through the barrier elements. However irrespective of this characteristic it must be mentioned that the area between the pivoted barrier elements is not covered over, the resulting opening thus representing a further obstacle. Finally it must be emphasised that the interchangeable unit preferably comprises three barrier elements; in the case of wider highway area having to be protected several units can be set in a row. In an embodiment of the invention it is suggested that the barrier device comprises at least two stages; one stage being formed by the barrier elements and the other stage being forced by at least one ramp-like element which can be swung out of the roadway and which is set at a distance to and behind the barrier elements in the driving direction. The following advantage is achieved by the dual-stage system. Should a vehicle sit on top of the barrier elements while they are swung out of the roadway surface, said vehicles cannot tip forward, since the front end of the vehicle would then be held by the ramp-like functioning element at a distance to the roadway surface, thus preventing the load from being tipped forward and out. Consequently the barrier device according to the invention is particularly suitable for use in military or diplomatic installations, which have to be effectively protected, for example against bomb attacks. In an embodiment of the invention the element is preferably arranged in the centre of the roadway, so that it is unnecessary to place several side by side. Of course it is also possible to insert the elements forming the second stage into the roadway staggered to each other, thus forming an effective barrier for vehicles of varying sizes. The ramp-like functioning element can be formed by at least two U-shaped iron sections in the longitudinal direction of the roadway, on which a steel plate is arranged which is flush with the roadway surface. The element, which can be pivoted out of the roadway surface, combines preferably with a hydraulic cylinder. It is furthermore proposed that the edge areas of the roadway surface encompassing the element are also made of steel plates, resulting in ease of maintenance. BRIEF DESCRIPTION OF THE DRAWINGS Further details, details, advantages and characteristics of the invention are not only contained in the claims, from which the characteristics can be drawn--singly or in combination--, but also from the following description of a preferred embodiment represented in the drawing. The figures show: FIG. 1: a principle representation of arrangements of barrier devices FIG. 2: a detailed representation of a barrier device with sunken barrier elements FIG. 3: the barrier device according to FIG. 2 with barrier elements swung out FIG. 4: a detailed representation of a barrier ramp FIG. 5: a top view of the barrier ramp according to FIG. 4 FIG. 6: a sectional representation along the line AA in FIG. 5 FIG. 7: an enlarged representation of a barrier device according to FIG. 1 and FIG. 8: a sectional representation along the line VIII--VIII in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 represents a multi-staged barrier arrangement for the blocking of a roadway (12) by choice in order to ensure that unauthorised or violent access to the highway equipped with the barrier arrangement is prevented. In the preferred embodiment the barrier arrangement comprises two barrier devices (10) and (11), of varying design which are set into the highway surface flush with it and at a distance to each other or can be swung out of the highway surface. The barrier arrangement according to the invention ensures that vehicles which may have overcome the outer barrier device (10) cannot tip forward onto the roadway (12), but are rather held in an upright position by the second barrier device (11), so that object for example on the loading surface of a vehicle cannot be swung in the direction of the area being protected. Detailed representations of the barrier devices (10) and (11) are containedin FIGS. 2 to 7, which are to be described in more detail as follows. In the embodiment according to FIGS. 2, 3 and 7 the first barrier device comprises three blocking elements (20, 22, 24), which each pivot around anaxle (14, 16, or 18). The axles (14, 16, 18) extend in the longitudinal direction of the highway (12), so that the blocking elements (20, 22, 24),which are posts, can be swung out of the highway (12) vertical to the normal travelling direction. Each post (20, 22, 24) has a counter-element or counter-weight (26, 28, 30) coordinating with it, which is arranged below ground independant of the position of the posts (20, 22, 24). The swing axles (14, 16, 18) extending in the area of the counter-elements (26, 28, 30) are moreover preferably arranged in the area of the centre ofgravity of the masses assembled by the elements (20, 26 or resp. 22, 28 or resp. 24, 30). This facilitates the pivotability of the barrier elements (20, 22, 24) with the counter-elements (26, 28, 30). Therefore pivoting results via a rod such as combining rods (34) which emanate from a motor organ such as a hydraulic cylinder (32); rod or rods being linked to the counter-elements (26, 28, 30) in the points (36, 38, 40) and if necessary sectioned. Operation of the hydraulic cylinder (32) takes places preferably from a metal cabin (42), so that when necessary the blocking elements (20, 22, 24) are swung out of the highway (12) or sunk into it. The posts (20, 22, 24) are in the area of the swing axles (14, 46,18) and are arranged in an overlapping manner above the said swing axles and support each other, resulting in a completely simple but yet statically sound construction. To achieve the overlapping the coordinated ends (48, 50)--represented in anexemplary fashion on the posts (20) and (22)--have graduated recesses (44 or 46) which complete each other. This permits the ends (48, 50) to lie ontop of each other above the axle (36) without the lateral areas (52, 54, 56) of the barrier posts (20, 22, 24) which are flush with the highway having to reveal unevenness. The front end (62) of a barrier element (20) not interacting with a neighbouring post is supported on a cement protrusion (60), thus achieving sufficient stability. FIG. 8 shows a sectional representation of the barrier element (24) according to the invention with the counter-element (30), in order to clarify their construction. The barrier element (24) as well as the counter-element (30) consist of a double-T girder whose flanges (118 and 120 or 122 and 124) are welded together. The flanges (118 and 122) are welded on the exterior with flat steels (only flat steel (126) is represented), thus providing a post enclosed on all sides as a barrier element (24). Furthermore reinforcing ribs can be welded inside the chamber formed by the flanges (118 and 122) and the flat steels to providethe barrier element with increased rigidity. Of course the chamber of the relevant double-T girders is also closed off by flat steels in the area of the free outer ends of the barrier elements.Furthermore it should be noted that the protrusions provided in the free ends (50) cause material bouncing against the barrier posts to be penetrated in a cutting fashion. FIG. 7 represents the barrier device (10) according to the invention in a blown-up representation to clarify their insertion into and extraction from the roadway. First of all a pit (128) is excavated out of the highway (12), on the floorof which (130) a cement floor is laid. Then a frame (132) is inserted into it with a dead mould (134) which can be made of sheet metal, so that finally the cavity between the dead mould (134) and the pit can be filled with cement. This provides a frame for the unit (136) which comprises the barrier elements (20, 22, 24 and 25) withthe counter-elements (26, 28, 30 and 31), the combining rods pivoting these as well as the drive equipment in the form of a hydraulic cylinder (in each case not represented). If this unit (136) is set on the frame (132) and screwed to it, the hydrauliccylinder can be connected with driving fluid, thus rendering the barrier device operational. Should for example one of the barrier elements become inoperational due to a defect or maintenance work the unit (136) simply has to be disconnected from the frame (132) and finally covering elements such as ramps have to be laid on the frame so that the roadway (12) can continue to be used. This guarantees that even in the case of a barrier device (10) not operating correctly the highway can be quickly cleared again for vehicles; an advantage not contained in the corresponding barrier devices to be drawn from the state of the art. The barrier elements (20, 22) represented alone at the top left in FIG. 7 with counter-elements (26 and 28) as well as pivot axles (14 and 16) have pipe support-shaped protrusions (138 and 140) running at right angles to their longitudinal axes. These block the area between the barrier elementsstanding adjacent, so that the barrier element (10) also forms an effectivebarrier blocking access for bicycles. The unit (136) provided in FIG. 2 with reference no. (58) and as underground assembley unit has preferably a hot-dip galvanised support construction out of U and double-T iron which is correspondingly suited tothe strains. Here the construction is fundamentally chosen so that each barrier post withstands strains of 100 tons at a vehicle speed of 30 km per hour without the pivotability being in any way influenced. The double-T girders of the barrier elements themselves have shaft lengths of preferably 300 mm, whereby the height of the area rising above the highwaysurface is approx. 650 mm. This height is sufficient to reach at least the axle area of almost all vehicles, so that in the case of a vehicle hittingthe barrier the vehicle becomes inoperable. The passable lateral areas (52, 54, 56) of the blocking posts (20, 22, 24) can be provided with a checkered plate which is not represented. Control for the hydraulic cylinder (32) and the pressure lay-out is chosen so that in the case of an electricity cut control can be maintained by a 24V battery, whereby operation of the barrier elements (20, 22, 24) several times is guaranteed by an energy storage unit. Furthermore in an emergency the barrier elements (20, 22, 24) can be sunk by means of a handpump. Consequently the barrier device (10) can be designated as being self-sufficient. In FIGS. 4 to 6 the second barrier device (11) is represented in detail, said device comprising a ramp-like functioning element (64) which can be swung out of the roadway (12) and which can be operated by a hydraulic cylinder (68) arranged in a shaft (66). In the preferred embodiment the element (64) consists of a steel plate (70) which is held by two U-shaped steel sections (72 or 74). The longitudinal axes of the U-shaped steel sections (72 and 74) extends in the longitudinal direction of the roadway.The element (64), which when sunk into the roadway is flush with the roadway (12), can be pivoted around an axle (76), whereby a shaft (78) necessary for this passes through the U-shaped steel sections (72) and (74). At a distance to the shaft (78) the hydraulic cylinder (68) engages into a shaft (80) also extending between the U-shaped steel sections (72 and 74) in order to thus swing the element (64) out of the highway surfaceor to render the element flush with it to the required extent. As in particular FIG. 1 clarifies, the element (64) is designed ramp-like to the first barrier stage (10), i.e. the pivoting axle (76) lies nearer to the first stage than the shaft (80). The edge (82) of the roadway (12) enclosing the element (64) is also preferably made of sheet metal to provide ease of maintenance. As FIG. 1 also shows, the element (64) is preferably arranged in the middleof the roadway (12) so that effective protection is guaranteed against vehicles which at least have partly overcome the first barrier (10), ie. are sitting on top of it and are in danger of tipping forwards. In order to prevent all normal vehicles which could possibly overcome the first barrier stage from tipping forwards it is sufficient if the element (64) is 400 mm wide and 1200 mm long, whereby the swing area of the highway surface should be 600 mm.	A vehicle barrier device 10 for the temporary blocking of a roadway 12 comprises blocking elements 20, 22, 24, 25 with joined conter-elements 26, 28, 30, 31. The blocking elements 20, 22, 24, 25 are pivotable around axles extending parallel to the main direction of the roadway 12 and are arranged either in the main flush with the roadway 12 or can be swung out of it. The barrier elements 20, 22, 24, 25 are inserted exchangeably into a frame 132 which is set into a pit 128 present in the roadway 12.	4
BACKGROUND OF THE INVENTION U.S. Pat. No. 4,672,501 entitled "Circuit Breaker and Protective Relay Unit" describes the use of a digital circuit interrupter employing a microprocessor in combination with ROM and RAM memory elements to provide both relaying as well as protection function to an electrical distribution system. U.S. Pat. No. 4,833,563 entitled "Molded Case Circuit Breaker Actuator-Accessory Module" describes an integrated protection unit that includes basic overcurrent protection facility along with selective electrical accessories. A specific actuator-accessory module is selected to give the required accessory function along with basic overcurrent protection. This patent describes transmission of a separate shunt trip signal directly to the actuator-accessory module without connection to the circuit breaker trip unit circuit. U.S. Pat. No. 5,539,605 entitled "Digital Circuit Interrupter Undervoltage Release Accessory" describes an independent undervoltage release module that provides auxiliary power to the circuit breaker trip unit to enable the trip unit microprocessor and to allow the microprocessor to report, display and record the undervoltage release information. U.S. patent application Ser. No. 08/614,084 filed Mar. 12, 1996 entitled "Modular Accessory Mechanical Lock-Out Mechanism" discloses a lockout solenoid arrangement that prevents an associated circuit breaker operating mechanism from closing until and unless the accessories have become reset. U.S. patent application Ser. No. 08/585,652 filed Jan. 16, 1996 entitled "Digital Circuit Interrupter Shunt Trip Accessory Module" discloses an integrated circuit breaker having shunt trip capability along with automatic overcurrent protection. An independent shunt trip module provides a shunt trip signal to the circuit breaker trip unit to actuate the trip unit flux shifter unit to interrupt separate the circuit breaker contacts and interrupt circuit current. The shunt trip module further supplies auxiliary power to the trip unit to allow the trip unit microprocessor to report and record the shunt trip operation. The shunt trip signal is applied to the circuit breaker trip unit by an operator from a separate voltage source inputted to the shunt trip module and thence to the circuit breaker trip unit. To prevent the trip unit flux shifter solenoid from overheating, a cut-off switch indicates to the trip unit to remove operating power from the flux shifter. If the shunt trip is still energized and the circuit breaker contacts are later energized, the flux shifter responds to again initiate contact separation, which could stress the circuit breaker contacts as well as the circuit breaker operating mechanism components. The subject invention proposes a shunt trip with lockout module that interacts with the circuit breaker trip unit to provide shunt trip circuit interruption as well as to energize an internal shunt trip lockout solenoid which interacts with the circuit breaker mechanism to prevent unintentional reclosure of the circuit breaker contacts. The energized shunt trip will also continue to supply operating power to the trip unit to allow the trip unit to communicate and display the shunt trip operation. SUMMARY OF THE INVENTION An integrated circuit breaker is described having shunt trip capability along with automatic overcurrent protection. An independent shunt trip module supplies a signal to the circuit breaker trip unit to interrupt circuit current and continues to provide auxiliary power to the trip unit to allow the trip unit microprocessor to display and record the shunt trip operation. A contact position indicating switch interacts with the circuit breaker operating mechanism to produce electrical indication to the trip unit as to the ON-OFF positions of the circuit breaker contacts. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a digital circuit interrupter that includes the shunt trip module according to the invention; and FIG. 2 is an enlarged diagrammatic representation of the components within the shunt trip module of FIG. 1; FIG. 3 is an enlarged diagrammatic representation of the circuit components within the output control module of FIG. 1. DESCRIPTION OF THE PREFERRED EMBODIMENT As described within the aforementioned U.S. Pat. No. 4,672,501, a circuit breaker trip unit 10 such as depicted in FIG. 1 to which external connection is made with current transformers 11-14 and potential transformers 15-17. The electrical input is transmitted through multiplexers 18-20 and sample and hold amplifiers 21, 22 to an A/D converter 24 by means of conductor 23. Circuit protection and control is achieved by utilization of a data bus 25 which is interconnected with an output control 26, transceiver 27, and RAM 28. The ROM 29, microprocessor 30 and nonvolatile memory 31 operate in the manner described therein to insure complete overall circuit protection. The information as to the status of the circuit breaker contacts (not shown) that are controlled by the output control 26 is displayed on the display 32 that is similar to that described in U.S. Pat. No. 4,870,531 entitled "Circuit Breaker With Removable Display and Keypad". Operating power to the trip unit power supply 41 is provided by the current transformers 11-14 from the associated electrical distribution system over conductor 40 when the associated electrical distribution system is operational. In accordance with the invention, shunt trip facility is provided by connection of a shunt trip module 33 with the microprocessor 30 over conductor 38, and auxiliary power is provided by connection with the trip unit power supply 41 by means of conductors 34, 35. Auxiliary power is supplied to the output control 26 by means of conductors 38 and 60. For purposes of this disclosure, the term "shunt trip" is defined as the provision of a trip signal to the circuit breaker trip unit independent of the circuit breaker trip unit which otherwise determines a trip operation based on the occurrence of an overcurrent condition. The shunt trip signal is often supplied to the input terminals 36, 37 by an operator remote from the circuit breaker location to either test the circuit breaker operating components or to electrically disconnect the associated electrical equipment for replacement and repair. Upon the provision of a shunt trip signal, the circuit breaker trip unit is disconnected from the electrical distribution circuit and hence, becomes in-active. To maintain operating power to the trip unit, in accordance with the invention, operating power is supplied by the shunt trip module to the trip unit circuit by continued application of the shunt trip voltage signal, hereafter "STVS" over terminals 36, 37 to the power supply 41 after the associated electrical distribution circuit has been interrupted. The occurrence of the shunt trip interruption is transmitted to the microprocessor over conductor for storage and display. In order to indicate the status of the circuit breaker contacts, a contact position switch module 39 is connected with the trip unit microprocessor 30 over conductor 60. The operation of the contact position switch module 39 is described in U.S. patent application Docket No. 41PR-7407 filed Feb. 3, 1997 entitled "Circuit Breaker Contact Position Indicating Unit" wherein a microswitch interacts with the circuit breaker operating mechanism drive shaft to provide electrical indication of the ON-OFF status of the associated circuit breaker contacts. The microprocessor determines the status of the circuit breaker contacts before energizing the flux shifter unit contained within the circuit breaker operating mechanism to retain the flux shifter plunger as described in the aforementioned U.S. Pat. No. 4,672,501. If the circuit breaker contacts are in the ON position, the flux shifter solenoid is actuated to trip the circuit breaker. The functional components of the shunt trip module 33 are depicted in FIG. 2 wherein the STVS supplied to input terminal 36 is inputted through a standard filter-surge compressor 42 to the comparator 43 for evaluation and thence over conductor 58 to a pulse generator 45 and one input to the isolation transformer 46 within the DC power supply 44. The function of the comparator is to insure that the STVS is an actual signal supplied by the operator and not a spurious voltage signal caused by a random electrical disturbance. The relevant electrical code requires that the STVS exceed fifty percent of the system voltage to insure that the STVS is intentional. The other input terminal 37 connects with the other input to the isolation transformer 46 over conductor 59, as indicated. The isolation transformer 46 connects through a pair of rectifying diodes 47, conductors 50, 51 and isolation diodes D1, D2 with a shunt trip solenoid control circuit 48 and with the trip unit 10. The shunt trip solenoid control arrangement is described in the aforementioned U.S. patent application Ser. No. 08/614,084. The shunt trip solenoid control circuit 48 provides an operating current signal to the shunt trip lockout solenoid in the following manner. The voltage signal is supplied over conductor to the drain of a FET 52 and to one side of a first power capacitor C1. The source of the FET connects with the shunt trip lockout solenoid 53 to interact with the circuit breaker operating mechanism . The gate of the FET 52 connects with the cathode of the isolation diode D2 via conductor 55 to control the ON-OFF state of the FET. The voltage signal is applied to the input of an inverter 54 and one side of a second capacitor C2 via conductor 55 within the trip unit power control circuit 49 to provide operating power to the trip unit over conductors 55, 56 for as long as the voltage signal is applied to the input terminals 36, 37 when the circuit breaker operating mechanism has responded to disconnect the trip unit from the associated electrical distribution system. When voltage is first applied to 36, 37, it causes the trip unit to be powered up and causes the circuit breaker to trip open. It also energizes the shunt trip lockout solenoid which interacts with the circuit breaker mechanism to prevent reclosure of the breaker. For as long as the voltage remains applied, the shunt trip lockout solenoid remains energized and thus intentionally prevent reclosure of the breaker. As described earlier, the ON and OFF states of the contacts within the circuit breaker are provided to the circuit breaker trip unit 10 by connection with the contact position switch module 39. Common ground connection between the shunt trip module 33 and the trip unit 10 is made by means of ground conductor 57. The output control circuit 26 is shown in FIG. 3 to include an AND gate 61 to which input is provided from the contact position switch module 39 and from the shunt trip module 33 over conductors 60 and 38. The output of the AND gate is connected to one input of an OR gate 62 with the other input to the OR gate connected with the data bus 25 of FIG. 1. The output of the OR gate is connected with the circuit breaker operating mechanism flux shifter unit. In operation, the trip request output from the shunt trip module 33 and the signal from the contact position switch module 39 are first AND'ed together and then OR'd with protection and other trip requests from the trip unit data bus 25 to create the signal to drive the flux shifter. The flux shifter will not operate to separate the circuit breaker contacts until all the above conditions are met. A shunt trip module has herein been described whereby the shunt trip signal supplied to circuit breaker flux shifter unit to separate the circuit breaker contacts and interrupt the associated electric circuit has herein been described. To prevent the circuit breaker operating mechanism from re-closing when the shunt trip remains energized and thus desired that the mechanism remain open, the shunt trip lockout solenoid remains energized and thus interlocks the mechanism and prevents re-closure of the breaker. Connection is made from a contact position switch to the trip unit to ensure that the trip unit only energizes the flux shifter to trip the breaker when the breaker is closed.	An integrated circuit breaker is provided with shunt trip capability along with automatic overcurrent protection through the circuit breaker trip unit and shunt trip module. The shunt trip module further provides auxiliary power to the trip unit and allows the trip unit microprocessor to report and record the shunt trip operation. The trip unit communicates with the circuit breaker operating mechanism to determine the ON-OFF status of the circuit breaker contacts.	7
CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. Prov. App. No. 62/002,470, filed May 23, 2014, and entitled “INTEGRATED PRODUCTION SIMULATOR BASED ON CAPACITANCE-RESISTANCE MODEL,” the disclosure of which is incorporated herein in its entirety. BACKGROUND [0002] Hydrocarbon reservoirs are exploited by drilling wells in a hydrocarbon bearing geologic formation. Both producing wells and injecting wells are typically used. The role of producing wells (producers) is to allow hydrocarbons to flow to the surface. Injecting wells (injectors) are drilled in order to maintain the reservoir pressure by injecting fluids (typically water or gas) to replace the produced fluids. [0003] The key to a successful exploitation operation of a petroleum reservoir is to efficiently design and operate wells. In order to guide and optimize well operations, simulators are often used. The role of reservoir simulators is to forecast the production of wells in order to evaluate the possible outcomes of operational changes. [0004] Reservoir simulators can be created in a variety of ways, but for the purpose of production optimization, it is desirable to take an approach that is both fast and accurate. The accuracy of the simulator is defined as the predictive power of the simulator: its ability to predict future well performance accurately and with a high level of confidence. The simulator's accuracy helps guarantee the economic success of the operational changes implemented. The speed of the simulator is defined as the time it takes to create or update a model and to perform a simulation. A fast simulator is desirable to update the model with new data in order to support daily operational decisions in a timely fashion. [0005] The standard approach followed in the petroleum industry to model reservoirs is to use grid-based reservoir simulators. These simulators often rely on a finite volume discretization of the equations governing the motion of reservoir fluids. Alternate discretization methods, such as finite element methods, are also used from time to time. These methods all have in common that the primary unknowns solved during the computation are the fluid pressures of each fluid phase and the composition of each fluid component. [0006] Classical grid-based reservoir simulation can be very accurate but is usually prohibitively slow. These models are large and require significant computer resources to run them. They are prohibitively slow for use in supporting day-to-day decisions related to production optimization. Grid-based reservoir simulation models are used primarily to support long-term field development decisions, such as the addition of new wells or changes to the exploitation strategy of the field. [0007] In recent years, a new type of reservoir simulation method has been developed in order to offer a faster alternative to classical grid-based reservoir simulators. This new class of methods, coined “Capacitance-Resistance” (“CR”) models in the literature, does not depend on solving the fluid pressures and compositions on a static geometric grid representing the reservoir geology. [0008] The fundamental difference between CR models and classical reservoir simulation models is that CR models rely on a reformulation of the equation governing the flow of fluids in porous media. Where classical reservoir simulation models are designed to find the fluid pressure and compositions within the reservoir, CR models directly solve for the well production rates of each fluid, without having to solve for the fluid pressure and compositions. [0009] Although much faster than classical reservoir simulation models, current CR models are limited in their application as they currently rely on a significant simplification of the reservoir flow equations. Critical limitations include neglecting the effect of fluid flow in the production or injection wellbore and surface facilities. At the reservoir level, these models neglect the effects of fluid compressibility, as well as capillary and gravitational forces. Current formulations also rely on a simplified description of the fluid system, involving only two fluid phases. BRIEF SUMMARY [0010] Embodiments described herein are directed to modeling a production system and generating a production forecast for individual wells. In one embodiment, a computer system accesses portions of first production system information from a capacitance-resistance model of the production system, where the production system corresponds to a production reservoir. The computer system further accesses portions of second production system information from a well-bore model, a flow line and/or a production facility. The computer system then generates an integrated production simulator using both the first and second accessed production systems information, and implements the integrated production simulator to determine the quantity of fluids produced per phase over time as a function of operational field parameters corresponding to the production system by identifying the flow rate for the production reservoir. [0011] In another embodiment, an integrated well-based production simulator system is provided. The integrated well-based production simulator system includes: a capacitance-resistance (CR) simulator configured to represent the flow of fluids in a production reservoir, a wellbore simulator configured to represent the flow of fluids in a wellbore, a surface facility simulator configured to represent the flow of fluids through at least one of the following surface facilities: pipelines, a production gathering facility, a separation facility, and an injection distribution facility, where the integrated well-based production simulator is configured to provide a system-wide representation of fluid flow through the production reservoir, the wellbore and at least one surface facility. [0012] In yet another embodiment, a computer system generates a production forecast for individual wells. The computer system accesses operational parameters for a well and provides an integrated well-based production simulator by solving a specified system of equations. The integrated well-based production simulator then generates a production forecast for the well using the operational parameters. [0013] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. [0014] Additional features and advantages will be set forth in the description which follows, and in part will be apparent to one of ordinary skill in the art from the description, or may be learned by the practice of the teachings herein. Features and advantages of embodiments described herein may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the embodiments described herein will become more fully apparent from the following description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0015] To further clarify the above and other features of the embodiments described herein, a more particular description will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only examples of the embodiments described herein and are therefore not to be considered limiting of its scope. The embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: [0016] FIG. 1 illustrates a computer-implemented or computer-controlled architecture that can be used to gather, analyze and/or display data gathered from and about a reservoir. [0017] FIG. 2 illustrates an example schematic of a production and injection system of a petroleum field. [0018] FIG. 3 illustrates a computer architecture in which embodiments described herein may operate including modeling a production system [0019] FIG. 4 illustrates a flowchart of an example method for modeling a production system. [0020] FIG. 5 illustrates a flowchart of an example method for generating a production forecast for individual wells. [0021] FIG. 6 illustrates an embodiment of an integrated well-based production simulator system. DETAILED DESCRIPTION [0022] Embodiments described herein are directed to modeling a production system and to generating a production forecast for individual wells. In one embodiment, a computer system accesses portions of first production system information from a capacitance-resistance model of the production system, where the production system corresponds to a production reservoir. The computer system further accesses portions of second production system information from a well-bore model, a flow line and/or a production facility. The computer system then generates an integrated production simulator using both the first and second accessed production systems information, and implements the integrated production simulator to determine the quantity of fluids produced per phase over time as a function of operational field parameters corresponding to the production system by identifying the flow rate for the production reservoir. [0023] In another embodiment, an integrated well-based production simulator system is provided. The integrated well-based production simulator system includes: a capacitance-resistance (CR) simulator configured to represent the flow of fluids in a production reservoir, a wellbore simulator configured to represent the flow of fluids in a wellbore, a surface facility simulator configured to represent the flow of fluids through at least one of the following surface facilities: pipelines, a production gathering facility, a separation facility, and an injection distribution facility, where the integrated well-based production simulator is configured to provide a system-wide representation of fluid flow through the production reservoir, the wellbore and at least one surface facility. [0024] In yet another embodiment, a computer system generates a production forecast for individual wells. The computer system accesses operational parameters for a well and provides an integrated well-based production simulator by solving a specified system of equations. The integrated well-based production simulator then generates a production forecast for the well using the operational parameters. [0025] The following discussion now refers to a number of methods and method acts that may be performed. It should be noted that, although the method acts may be discussed in a certain order or illustrated in a flow chart as occurring in a particular order, no particular ordering is necessarily required unless specifically stated, or required because an act is dependent on another act being completed prior to the act being performed. [0026] Embodiments described herein may implement various types of computing systems. These computing systems are now increasingly taking a wide variety of forms. Computing systems may, for example, be handheld devices, appliances, laptop computers, desktop computers, mainframes, distributed computing systems, or even devices that have not conventionally been considered a computing system. In this description and in the claims, the term “computing system” is defined broadly as including any device or system (or combination thereof) that includes at least one physical and tangible processor, and a physical and tangible memory capable of having thereon computer-executable instructions that may be executed by the processor. A computing system may be distributed over a network environment and may include multiple constituent computing systems. [0027] Computing systems (e.g. 102 in FIG. 1 ) typically include at least one processing unit and memory. The memory may be physical system memory, which may be volatile, non-volatile, or some combination of the two. The term “memory” may also be used herein to refer to non-volatile mass storage such as physical storage media. If the computing system is distributed, the processing, memory and/or storage capability may be distributed as well. [0028] As used herein, the term “executable module” or “executable component” can refer to software objects, routings, or methods that may be executed on the computing system. The different components, modules, engines, and services described herein may be implemented as objects or processes that execute on the computing system (e.g., as separate threads). [0029] In the description that follows, embodiments are described with reference to acts that are performed by one or more computing systems. If such acts are implemented in software, one or more processors of the associated computing system that performs the act direct the operation of the computing system in response to having executed computer-executable instructions. For example, such computer-executable instructions may be embodied on one or more computer-readable media that form a computer program product. An example of such an operation involves the manipulation of data. The computer-executable instructions (and the manipulated data) may be stored in the memory of the computing system 102 . Computing systems may also contain communication channels that allow the computing system to communicate with other message processors over a wired or wireless network. [0030] Embodiments described herein may comprise or utilize a special-purpose or general-purpose computer system that includes computer hardware, such as, for example, one or more processors and system memory, as discussed in greater detail below. The system memory may be included within the overall memory. The system memory may also be referred to as “main memory”, and includes memory locations that are addressable by the at least one processing unit over a memory bus in which case the address location is asserted on the memory bus itself. System memory has been traditionally volatile, but the principles described herein also apply in circumstances in which the system memory is partially, or even fully, non-volatile. [0031] Embodiments within the scope of the present invention also include physical and other computer-readable media for carrying or storing computer-executable instructions and/or data structures. Such computer-readable media can be any available media that can be accessed by a general-purpose or special-purpose computer system. Computer-readable media that store computer-executable instructions and/or data structures are computer storage media. Computer-readable media that carry computer-executable instructions and/or data structures are transmission media. Thus, by way of example, and not limitation, embodiments of the invention can comprise at least two distinctly different kinds of computer-readable media: computer storage media and transmission media. [0032] Computer storage media are physical hardware storage media that store computer-executable instructions and/or data structures. Physical hardware storage media include computer hardware, such as RAM, ROM, EEPROM, solid state drives (“SSDs”), flash memory, phase-change memory (“PCM”), optical disk storage, magnetic disk storage or other magnetic storage devices, or any other hardware storage device(s) which can be used to store program code in the form of computer-executable instructions or data structures, which can be accessed and executed by a general-purpose or special-purpose computer system to implement the disclosed functionality of the invention. [0033] Transmission media can include a network and/or data links which can be used to carry program code in the form of computer-executable instructions or data structures, and which can be accessed by a general-purpose or special-purpose computer system. A “network” is defined as one or more data links that enable the transport of electronic data between computer systems and/or modules and/or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer system, the computer system may view the connection as transmission media. Combinations of the above should also be included within the scope of computer-readable media. [0034] Further, upon reaching various computer system components, program code in the form of computer-executable instructions or data structures can be transferred automatically from transmission media to computer storage media (or vice versa). For example, computer-executable instructions or data structures received over a network or data link can be buffered in RAM within a network interface module (e.g., a “NIC”), and then eventually transferred to computer system RAM and/or to less volatile computer storage media at a computer system. Thus, it should be understood that computer storage media can be included in computer system components that also (or even primarily) utilize transmission media. [0035] Computer-executable instructions comprise, for example, instructions and data which, when executed at one or more processors, cause a general-purpose computer system, special-purpose computer system, or special-purpose processing device to perform a certain function or group of functions. Computer-executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. [0036] Those skilled in the art will appreciate that the principles described herein may be practiced in network computing environments with many types of computer system configurations, including, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, pagers, routers, switches, and the like. The invention may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. As such, in a distributed system environment, a computer system may include a plurality of constituent computer systems. In a distributed system environment, program modules may be located in both local and remote memory storage devices. [0037] Those skilled in the art will also appreciate that the invention may be practiced in a cloud computing environment. Cloud computing environments may be distributed, although this is not required. When distributed, cloud computing environments may be distributed internationally within an organization and/or have components possessed across multiple organizations. In this description and the following claims, “cloud computing” is defined as a model for enabling on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services). The definition of “cloud computing” is not limited to any of the other numerous advantages that can be obtained from such a model when properly deployed. [0038] Still further, system architectures described herein can include a plurality of independent components that each contribute to the functionality of the system as a whole. This modularity allows for increased flexibility when approaching issues of platform scalability and, to this end, provides a variety of advantages. System complexity and growth can be managed more easily through the use of smaller-scale parts with limited functional scope. Platform fault tolerance is enhanced through the use of these loosely coupled modules. Individual components can be grown incrementally as business needs dictate. Modular development also translates to decreased time to market for new functionality. New functionality can be added or subtracted without impacting the core system. [0039] FIG. 1 illustrates a computing architecture in which a computer-implemented monitoring system 100 may operate. The computer-implemented monitoring system 100 may be configured to monitor reservoir performance, analyze information regarding reservoir performance, display dashboard metrics, and optionally provide for computer-controlled modifications to maintain optimal oil well performance. Monitoring system 100 may include a main data gathering computer system 102 comprised of one or more computers (potentially located near a reservoir) which are linked to reservoir sensors 104 . Each of these computers typically includes at least one processor and system memory. Computer system 102 may comprise a plurality of networked computers (e.g., each of which is designed to analyze a subset of the overall data generated by and received from the sensors 104 ). [0040] Reservoir sensors 104 are typically positioned at different locations within a producing oil well, and may include both surface and sub-surface sensors. Sensors 104 may also be positioned at water injection wells, observation wells, etc. The data gathered by the sensors 104 can be used to generate performance metrics (e.g., leading and lagging indicators of production and recovery). The computer system 102 may therefore include a data analysis module 106 programmed to generate metrics from the received sensor data. A user interface 108 provides interactivity with a user, including the ability to input data relating to a real displacement efficiency, vertical displacement efficiency, and pore displacement efficiency. Data storage device 110 can be used for long term storage of data and metrics generated from the data. [0041] According to one embodiment, the computer system 102 can provide for at least one of manual or automatic adjustment to production 112 by reservoir production units 114 (e.g., producing oil wells, water injection wells, gas injection wells, heat injectors, and the like, and sub-components thereof). Adjustments might include, for example changes in volume, pressure, temperature, well bore path (e.g., via closing or opening of well bore branches). The user interface 108 permits manual adjustments to production 112 . The computer system 102 may, in addition, include alarm levels or triggers that, when certain conditions are met, provide for automatic adjustments to production 112 . [0042] Monitoring system 100 may also include one or more remote computers 120 that permit a user, team of users, or multiple parties to access information generated by main computer system 102 . For example, each remote computer 120 may include a dashboard display module 122 that renders and displays dashboards, metrics, or other information relating to reservoir production. Each remote computer 120 may also include a user interface 124 that permits a user to make adjustment to production 112 by reservoir production units 114 . Each remote computer 120 may also include a data storage device (not shown). [0043] Individual computer systems within monitoring system 100 (e.g., main computer system 102 and remove computers 120 ) can be connected to a network 130 , such as, for example, a local area network (“LAN”), a wide area network (“WAN”), or even the Internet. The various components can receive and send data to each other, as well as other components connected to the network. Networked computer systems (i.e. cloud computing systems) and computers themselves constitute a “computer system” for purposes of this disclosure. [0044] Networks facilitating communication between computer systems and other electronic devices can utilize any of a wide range of (potentially interoperating) protocols including, but not limited to, the IEEE 802 suite of wireless protocols, Radio Frequency Identification (“RFID”) protocols, ultrasound protocols, infrared protocols, cellular protocols, one-way and two-way wireless paging protocols, Global Positioning System (“GPS”) protocols, wired and wireless broadband protocols, ultra-wideband “mesh” protocols, etc. Accordingly, computer systems and other devices can create message related data and exchange message related data (e.g., Internet Protocol (“IP”) datagrams and other higher layer protocols that utilize IP datagrams, such as, Transmission Control Protocol (“TCP”), Remote Desktop Protocol (“RDP”), Hypertext Transfer Protocol (“HTTP”), Simple Mail Transfer Protocol (“SMTP”), Simple Object Access Protocol (“SOAP”), etc.) over the network. [0045] Computer systems and electronic devices may be configured to utilize protocols that are appropriate based on corresponding computer system and electronic device on functionality. Components within the architecture can be configured to convert between various protocols to facilitate compatible communication. Computer systems and electronic devices may be configured with multiple protocols and use different protocols to implement different functionality. For example, a sensor 104 at an oil well might transmit data via wire connection, infrared or other wireless protocol to a receiver (not shown) interfaced with a computer, which can then forward the data via fast Ethernet to main computer system 102 for processing. Similarly, the reservoir production units 114 can be connected to main computer system 102 and/or remote computers 120 by wire connection or wireless protocol. [0046] As indicated above, a capacitance-resistance model (or CR model) may be used to characterize the connectivity between injection and production wells and can determine an injection scheme that maximizes the value of the reservoir asset. CR model parameters are identified using linear and nonlinear regression. The CR model is then used together with a nonlinear optimization algorithm to compute a set of future injection rates which maximize discounted net profit. CR models solve for production rates of each fluid without solving for fluid pressure and compositions (as in grid-based). CR models, however, neglect fluid flow in production facilities and wellbores and neglect the effects of fluid compressibility and capillary and gravitational forces, and are limited to two fluid phases. [0047] Embodiments described herein include a reservoir simulator accurate enough to generate a reliable forecast of individual wells as a function of operational parameters and fast enough to be used in practice to drive the operational decisions required to optimize the exploitation of petroleum reservoirs. The speed of the reservoir simulator is due to multiple factors including a differentiated formulation and solution workflow. [0048] FIG. 2 illustrates a schematic of a production and injection system of a petroleum field. The production wells 203 allow reservoir fluids (from reservoir 208 ) to flow through their completion 204 and to the surface, where a network of pipelines (e.g. production tubing 205 ) carry the fluids to production gathering facilities 202 , and in turn, to a separator 201 . The separator system isolates each fluid phase (typically oil, gas and water). In some cases, the water or gas produced and separated are then sent to an injection distribution system 206 . The injection distribution system can also receive injection fluids from exterior sources. The injection wells 207 receive the fluids to be injected from the injection distribution system 206 via a network of pipelines and inject these fluids in the petroleum reservoirs through well completions 204 . [0049] In some embodiments, reservoir fluid mixtures may be composed of two or more phases. For example, two phases may be considered in the following derivation, where the oil phase is designated with the subscript “o” and the water phase with the subscript “w”. Embodiments may be extended to more complex fluid compositions including three or more fluid phases. In this example, a producing well is located in a hydrocarbon reservoir. Naming V the drainage volume of the well, the mass balance equation over the water and oil fluid components written over the drainage volume of the well can be expressed as: [0000]  S w  t + S w  ( c w + c f )   p  t + q w - i w V = 0 , and ( Eq .  1 )  S o  t + S o  ( c o + c f )   p  t + q o V = 0. ( Eq .  2 ) [0050] In Eq. 1 and 2, t designates a time variable. The unknowns of the equations are p, the fluid pressure, as well as S w and S o , the water and oil saturations. c w , c o and c f are respectively, the water, oil and rock formation compressibility. q o and q w are the oil and water production rates of the well of interest and i w is the water injection rate received by the drainage volume of the well. To close the system, the fundamental property of the oil and water saturation is used: [0000] S w +S o =1. (Eq. 3) [0051] In some cases, reservoir simulators may be configured to directly solve the system formed by Eq. 1 and 2 using a numerical discretization method on a grid describing the reservoir geometry and rock properties. Various approaches may be used including finite difference, finite volume and finite element methods. Simulators typically solve simultaneously the pressure and saturation unknowns, using a scheme referred to as a fully-implicit scheme. Some simulators solve the pressure and saturation unknowns sequentially. [0052] Summing Eq. 1 and 2, and using Eq. 3 to simplify the saturation derivatives, the pressure equation may be obtained, describing the flow problem: [0000] c t  V   p  t + q t - i w = 0 ( Eq .  4 ) [0000] where the total production rate q t =q o +q w is defined along with the total compressibility c t =(S o c o +S w c w +c f ). [0053] Some reservoir simulators may rely on Eq. 4 to solve for the fluid pressure throughout the reservoir, and then solve either Eq. 1 or Eq. 2 in order to obtain the fluid saturations. This solution approach is called the implicit-pressure-explicit-saturation approach and is known to speed up simulation runtime as it allows the numerical discretization algorithms to be tailored to the mathematical character of each equation. The pressure equation of Eq. 4 describes the flow problem, which is near-parabolic in nature, the saturation equations of Eq. 1 and 2 describe the transport problem, which is near-hyperbolic in nature. [0054] Introducing the productivity index J of the producing well, the equation linking the total production rate to the reservoir pressure reads: [0000] q t =j ( p−p BH ) (Eq. 5) [0000] where p BH designates the bottom-hole pressure of the producing well. [0055] By differentiating Eq. 5 with respect to time and replacing the reservoir pressure derivative term in Eq. 4, an equation may be obtained that depends solely on the pressure and rate of the producing well: [0000] τ   q t  t + q t = i w - c t  V   p BH  t  ( Eq .  6 ) [0000] where [0000] τ = c t  V J [0000] is defined as a time constant. [0056] The CR models solve a system of equation composed of a form of Eq. 6 and either Eq. 1 or Eq. 2. The fundamental difference between CR models and classical reservoir models is that Eq. 6 does not involve the reservoir pressure. Instead, the production rate of the well is determined directly. This difference provides a speed advantage for CR models over traditional methods. [0057] Embodiments described herein are designed to integrate the production system 202 and the injection system 206 . CR models are typically used solely as reservoir simulators. The fundamental unknowns of CR models are the production rates of each fluid component. The well bottom-hole pressure is usually seen as a constraint on the producing well. In reality, the bottom-hole pressure is often an unknown just as much as the production rates. The effective well constraint of a well could be located in a variety of upstream locations including, but not limited to, the tubing-head pressure, the flow-line pressure, the manifold pressure or separator pressure. Each of these locations may be constraints on a well's production. [0058] To more completely model the production system, embodiments herein implement CR models in conjunction with models of the wellbore, surface flow-lines and associated production facilities to create an integrated production model. To do so, the bottom-hole pressure of Eq. 6 is viewed as an unknown rather than a constraint and additional equations are introduced to represent the dependence of the bottom-hole pressure on the architecture of the production system. This approach allows the CR model to be constrained by the actual control mechanisms in the field, such as well-head choke size or artificial lift parameters. [0059] Several possible levels of control are possible including the tubing head pressure, p TH , and the flow-line pressure, p FL , located at the well-head upstream and downstream of the choke, respectively. Further downstream, pressures at other flow-lines, manifolds or separators could also be used. These are labeled p DS to designate a general downstream pressure. [0060] Relating the pressures along the production facility system, from the wellbore to the separator is an exercise often performed by Petroleum or Chemical Engineers. A variety of approaches may be used depending on the system components and flow conditions. Any approach will result in a modeling of the system that will link a downstream pressure, p DS to the bottom-hole pressure, p BH and flow rates of each fluid component; here, q o and q w are considered for completeness, but the approach is not limited to such relatively simplistic systems. The production system may be modeled through a function f p c1 , . . . , p cm facility , such that: [0000] p BH =f p c1 , . . . , p cm facility ( p DS , q 0 , q w ) (Eq. 7) [0000] where p c1 , . . . , p cm are m independent control parameters on the system. [0061] Combining Eq. 7 with the previous system composed of Eq. 5 and Eq. 1 or Eq. 2 leads to an integrated well-based production simulator (e.g. as shown in FIG. 6 ). [0062] In different embodiments of the method, f p c1 , . . . , p cm facility can take various forms. If the dynamics of the flow in the production system are simple enough, the function can be an analytical formula, explicitly expressing the dependence of the bottom-hole pressure to the downstream pressure, flow rates and operational parameters. In other, more complex cases, a numerical model of the flow equations may be used, so that the function will be embodied as a simulator of wellbore flow dynamics and/or a surface facility simulator. In one embodiment, the function can take the form of a table of pre-computed solutions. Such vertical lift tables may be used to represent the well flow dynamics in reservoir simulation software. These concepts will be explained further below with regard to methods 400 and 500 of FIGS. 4 and 5 , respectively. [0063] In view of the systems and architectures described above, methodologies that may be implemented in accordance with the disclosed subject matter will be better appreciated with reference to the flow charts of FIGS. 4 and 5 . For purposes of simplicity of explanation, the methodologies are shown and described as a series of blocks. However, it should be understood and appreciated that the claimed subject matter is not limited by the order of the blocks, as some blocks may occur in different orders and/or concurrently with other blocks from what is depicted and described herein. Moreover, not all illustrated blocks may be required to implement the methodologies described hereinafter. [0064] FIG. 4 illustrates a flowchart of a method 400 for modeling a production system. The method 400 will now be described with frequent reference to the components and data elements shown in FIGS. 1 , 2 and 3 , respectively. [0065] Method 400 includes accessing one or more portions of first production system information from a capacitance-resistance model of the production system, the production system corresponding to at least one production reservoir ( 410 ). For example, accessing module 307 of computer system 301 may be configured to access first production system information 315 received from production reservoir 314 . The first production system information 315 may be used by the capacitance-resistance (CR) model 308 to model a production system 320 . The production system 320 may include, for example, production reservoir 314 , well-bore model 317 , flow lines 318 and/or a production facility 319 . Each of these production system components may cause constraints on the production of fluids such as petroleum. [0066] As such, the CR model 308 takes into account production system information for the production system 320 as a whole and generates production forecasts 313 based on simulations provided by the model. Each of the modules of computer system 301 may interact with or be processed by processor 302 and/or memory 303 . Moreover, communications with other computing systems or users may occur using the communications module 304 . For example, first and second production system information 315 and 316 may be received from other computing systems. Similarly, user 305 may interact with the computer system 301 using input 306 , which is received at the communications module 304 . [0067] Method 400 further includes accessing one or more portions of second production system information from at least one of a well-bore model, a flow line and a production facility ( 420 ). As indicated above, a production system (e.g. 320 ) includes multiple different elements, including a production reservoir 314 , a well-bore 317 , a flow line 318 and a production facility 319 , among others. The second production system information 316 may be sent from any of these elements including a well-bore model 317 (or directly from well-bore datasets), from flow line data 318 or from production facility data 319 . Each of these parts of the production system 320 may introduce different pressures or forces on the production material (oil, water, gas, etc.). And, as such, each part may introduce constraints on the production system, reducing or increasing efficiency in some manner. [0068] An integrated production simulator 310 may be configured to take both first production system information 315 and second production system information 316 into account when generating a production forecast 313 for a production system. The integrated production simulator may be generated using both the first and second accessed production system information ( 430 ). The simulator generating module 309 of computer system 101 , for example, may generate integrated production simulator 310 , which may be used to determine the quantity of fluids produced per phase over time as a function of operational field parameters corresponding to the production system by identifying the flow rate for the production reservoir ( 440 ). Thus, the simulator 310 may not only be used to generate production forecasts, but also to determine the quantity of fluids 311 produced per phase (e.g. separately for oil, gas and water, or other phases). The simulator determines the quantity of fluids produced per phase over time as a function of operational field parameters corresponding to the production system by identifying the flow rate 312 for the production reservoir. The operational field parameters may include well-head choke size, artificial lift parameters or other field parameters. In this manner, the integrated production simulator 310 is constrained by actual control mechanisms used in a production system. [0069] In some embodiments, the determined quantity of fluids produced per phase over time as a function operational field parameters corresponding to the production system 320 may be further analyzed by computer system 301 to determine whether additional operations are to be initiated on the production system. In some cases, the further analysis may indicate that a certain flow line is reducing fluid flow, or a certain well-bore or portion of a production facility is reducing efficiency in producing material. Accordingly, in such cases, additional operations may be undertaken to increase fluid flow in the determined flow line 318 . Other operations may be initiated to increase efficiency in the well bore 317 or the determined portion(s) of the production facility 319 . [0070] If it is determined that additional operations are to be initiated on one or more components the production system 320 , the computer system 301 may analyze the determined quantity of fluids produced per phase over time as a function of the operational field parameters corresponding to the production system to determine the degree to which the additional operations are to be performed. Accordingly, if fluid flow is drastically reduced at a particular component, the computer system 301 may indicate that operations are to be taken immediately in relation to that component to a degree sufficient to counteract the reduction in fluid flow. [0071] The integrated production simulator 310 may thus simulate and show where constraints exist across each piece of the production system 320 . The integrated production simulator 310 is configured to show the flow of petroleum and aqueous fluids from the production reservoir through the production facility. In some cases, identifying the flow rate for the production reservoir includes identifying a production rate for one or more fluids in the production reservoir. These fluids may include water, gas, oil or other fluids. The integrated production simulator 310 may be configured to account for fluid flow in both the well-bore and the production facility. The integrated production simulator 310 may further be configured to account for fluid compressibility, capillary forces and/or gravitational forces. As such, the integrated production simulator 310 may provide a more complete and more thorough indication of operating conditions of a particular production system. Determinations of fluid compressibility, capillary forces and gravitational forces act to remove variables in the simulations, and thus provide a more accurate production forecast 313 or indication of the quantity of fluids 311 produced per phase over time. [0072] In some cases, the integrated production simulator 310 is configured to model the bottom-hole's dependence on one or more components of production system architecture (e.g. components 314 , 317 , 318 or 319 ). The bottom-hole pressure for the production system 320 may be identified as an unknown element, as opposed to being identified as a constraint. This may further allow the integrated production simulator 310 to provide a more accurate production forecast 313 and/or indication of the quantity of fluids 311 produced per phase over time. [0073] As shown in FIG. 6 , the integrated well-based production simulator 601 comprises a system that includes: a capacitance-resistance (CR) simulator 602 configured to represent the flow of fluids in a production reservoir, a well-bore simulator 603 configured to represent the flow of one or more fluids in a wellbore, and a surface facility simulator 604 configured to represent the flow of fluids through surface facilities including pipelines, production gathering facilities, separation facilities and injection distribution facilities. Because the integrated well-based production simulator 601 analyzes data from a CR simulator, a well-bore simulator and a surface facility simulator, the integrated simulator 601 can provide a system-wide representation of fluid flow 605 through the production reservoir, the wellbore and any one or more of the surface facilities. [0074] At least in some embodiments, the fluids in the production reservoir include petroleum and various aqueous fluids. These fluids may flow to a separator (e.g. 201 of FIG. 2 ) that is configured to isolate each fluid phase. For instance, the separator 201 may isolate the fluids into at least three fluid phases including oil, gas and water. The fluid phases may be analyzed as being compressible when providing a system-wide representation of fluid flow through the production reservoir. Accounting for compressibility allows the integrated well based production simulator 601 to provide a more accurate production system simulation. Along these lines, capillary forces and gravity forces may also be analyzed when providing a system-wide representation of fluid flow through the production reservoir 208 . [0075] The integrated well-based production simulator 601 may be designed to include different levels of control including the ability to control tubing head pressure, flow-line pressure located at the well head upstream and downstream of the choke, and downstream pressures of flow-lines, manifolds or separators. In this manner, a user (e.g. 305 of FIG. 3 ) may use input 306 to control the tubing head pressure, flow-line pressure or downstream pressures. These may be controlled manually or may be adjusted automatically upon a determination by the integrated production simulator that certain production system 320 components are causing flow constraints. [0076] In some cases, the well-based production simulator may be designed to implement a flow function to determine fluid flow for the integrated well-based production simulator system 310 . The function may include an analytical formula that expresses dependence on bottom-hole pressure to downstream pressure, dependence on flow rates and/or dependence on operational parameters such as well-head choke size and artificial lift parameters. Still further, the integrated well-based production simulator may be designed to implement a numerical model of a flow function to determine fluid flow for the integrated well-based production simulator system. As such, the flow function includes a surface facility simulator and/or a simulator of wellbore flow dynamics. At least in some cases, the flow function may include a table of pre-computed solutions. Thus, as can be seen, the well-based production simulator may be designed to include multiple different features and functionality components in order to provide highly accurate indications of fluid flow through a production system 320 . [0077] Turning now to FIG. 5 , a flowchart of a method 500 is illustrated for generating a production forecast for individual wells. The method 500 will now be described with frequent reference to the components and data elements of FIGS. 1 , 2 and 3 , respectively. [0078] Method 500 includes accessing one or more operational parameters for a well ( 510 ). The operational parameters, as indicated above, may be used to determine the quantity of fluids 311 produced per phase over time as a function of these operational field parameters. The simulator generating module 309 of computer system 301 may use the operational parameters to provide integrated well-based production simulator 310 by solving the following system of equations ( 520 ): [0000] p BH =f p c1 , . . . , p cm facility ( p DS , q o , q w ), (Eq. 7) [0000] where p c1 , . . . , p cm comprise m independent operational parameters for the well, [0000] q t =j ( p−p BH ), (Eq. 5) [0079] which links a total production rate to the reservoir pressure, and [0000]  S w  t + S w  ( c w + c f )   p  t + q w - i w V = 0 , ( Eq .  1 ) [0000] which provides a mass conservation condition over one or more fluid components written over the drainage volume of the well, where V comprises the drainage volume of the well. Once instantiated, the generated production simulator 310 may create a production forecast for the well using the accessed operational parameters ( 530 ). [0080] Within this production simulator 310 , the bottom-hole pressure may be treated as an unknown, and as such, may depend on the architecture of the production system 320 . This allows the production forecast to take into account multiple different factors, different designs, different architectures, and different physical conditions present in the various components of the production system 320 . The production forecast may be generated quickly enough to drive operational decisions used to optimize the exploitation of petroleum reservoirs. Moreover, the production forecast 313 shows increased accuracy as it is based on actual production system information received from actual, working production system components. [0081] Accordingly, methods, systems and computer program products are provided which model a production system, taking into account each of the different components of the production system. Moreover, methods, systems and computer program products are provided which generate a production forecast for individual wells. [0082] The concepts and features described herein may be embodied in other specific forms without departing from their spirit or descriptive characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.	A well-based production simulator is provided, which predicts the quantity of fluids produced per phase, per well and per time as a function of operational field parameters. The invention combines a petroleum reservoir simulator with a petroleum production facility simulator to obtain an integrated model to quickly and accurately forecast production on a well-by-well basis. The efficiency of the petroleum reservoir simulator is derived from its unique formulation, which solves for the production well's flow rate rather than the petroleum reservoir pressure. The simulator properly represents viscous, capillary and gravity forces, as well as complex fluid descriptions, including three-phase black-oil formulations.	4
BACKGROUND OF THE INVENTION The instant invention relates to apparatus and a process for monitoring respiration as well as to a conductive gel used therewith, wherein the apparatus comprises at least first and preferably second circumferential gauges that attach around a patient's abdomen and chest to monitor expansion thereof as the patient breaths. The gauges are configured as hollow tubes containing the new and improved conductive gel. In the past, continuous volumetric monitoring of patients' ventilation generally involved use of face masks or mouthpieces, approaches which are not only invasive and uncomfortable to the patient but also interfere with the very breathing patterns being measured. These approaches required considerable cooperation from patients, which cooperation was compromised if the patient was critically ill, comatose, or very young. In addition, leaving mouthpieces in place was a danger in and of itself in that mouthpieces can suffocate patients. Utilizing these invasive methods required constant supervision and attention, further limiting the desirability of these techniques. In view of such deficiencies, noninvasive techniques were developed such as those exemplified in U.S. Pat. Nos. 3,268,845 and 3,483,861, wherein respiration is monitored by measuring expansion of the patient's torso at primary levels of respiration; namely, expansion of the thoracic cavity, diaphragm, and abdomen. A current approach is shown in U.S. Pat. No. 4,373,534, wherein inductive loops are positioned around the thoracic cavity and abdomen. As the patient breathes, the inductive loops expand and contract, resulting in changes in cross-sectional area and inductance of the loops. Monitoring these changes provides a measure of respiration volume. This has been performed in research for a number of years, using mercury in rubber gauges. The art has continued to progress to current approaches, wherein elastic tubes containing mercury or aqueous solutions are used. Mercury is a material which should, if possible, be avoided since exposure to mercury presents a severe health hazard. As was pointed out in Brouillette et al., "Comparison of Respiratory Inductive Plethysmography and Thoracic Impedance for Apnea Monitoring," Journal of Pediatrics, September 1987, pp. 377-383, incorporated herein by reference, respiratory inductive plethysmographs have advantages over conventional thoracic impedance monitors for infants. Plethysmographs need to be substantially modified before being used for routine monitoring of infants in hospitals or at home. Moreover, the cost is excessive and the associated systems complex. One approach has been to use natural rubber tubes containing a conductive aqueous solution. However, rubber tubes containing aqueous solutions have been found to have a limited shelf-life of six to ten months and an active life of only 48 hours. Accordingly, they are only useful for overnight diagnostic recordings. Continuous monitoring over several days using such tubes results in considerable expense, since the tubes must be replaced repeatedly. The concept of a rubber tube with an aqueous solution has the advantage of generating very clear signals with low noise generated by physiological and electronic interference. Apparently, the shelf-life of these devices in a Mylar storage envelope and active life after the envelope is opened is limited by passage of the aqueous solution through the walls of the gauge. Another general deficiency of prior art devices is that these devices are incapable of obtaining rapid, quantitative, absolute measurements which are accurate. In view of the aforementioned considerations, there is a need for an improved apparatus and method which monitors respiration with accuracy and absolute values, which apparatus has signal-to-noise ratio advantages of currently available natural tubes with aqueous electrolytes, yet have both extended shelf-life and extended active life. SUMMARY OF THE INVENTION In the apparatus aspect of the invention, there is provided apparatus for detecting expansion and contraction of a body, comprising: an elastic tube having first and second sealed ends and containing therein a conductive gel comprising glycerol, water, and at least one conductive salt contained within the tube, which gel changes in inductance as the tube is stretched; and first and second connectors at first and second ends of the tube in electrical contact with the gel, wherein as the tube stretches, changes in the inductance thereof is measured by current flowing between the contacts through the conductive gel. The instant invention further contemplates a conductive fluid or gel containing water and glycerol, 35-90% by volume and preferably 50-70% by volume and at least one of the following salts: NaCl, preferably from about 20% (g/100 ml) by volume to saturated solution; KCl, preferably from about 20% (g/100 ml) by volume to saturated solution; and sodium or potassium acetate, preferably from about 20% (g/100 ml) by volume to saturated solution; calcium lactate, preferably from about 20% (g/100 ml) by volume to saturated solution; and magnesium sulfate, preferably from about 20% by volume to saturated solution. It is particularly preferred that the salts be present as a saturated solution. The instant invention further contemplates an apparatus for measuring tidal volume noninvasively by encircling a patient's chest and abdomen with at least one silicone rubber tube filled with a nontoxic hygroscopic electrolyte. Each tube has first and second ends sealed with first and second electrical contacts which are in contact with the electrolyte. As the tubes stretch, the impedance of the electrolyte changes. This change in impedance is detected by changes in pulsed current flowing through the electrolyte between the contacts as measured in a constant amperage circuit. Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features, and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings in which like reference characters designate the same or similar parts throughout the several views, and wherein: FIG. 1 is a diagram showing attachment of the apparatus of the instant invention to a patient; FIG. 2 is a planar view of one gauge of the instant invention shown in its relaxed state before being attached to the patient; FIG. 3 is a planar view of a second embodiment of the gauge having a pair of silicone rubber tubes, rather than a single tube; FIGS. 4A and 4B are graphs illustrating change in voltage as a function of tube stretch; FIG. 5 is a graph illustrating that the voltage rate in millivolts/centimeter remains substantially constant between 18-24 cm when the tube in accordance with the instant invention is in a relaxed state; FIG. 6 is a diagram showing how the tubular gauges of the instant invention are calibrated; and FIG. 7 is a schematic diagram of a circuit for processing information from the tubular gauges shown applied to the patient in FIG. 1. DETAILED DESCRIPTION Referring now to FIG. 1, there is shown a patient designated generally by the numeral 10 having a chest or thorax 11, a diaphragm generally illustrated by the numeral 12; and an abdomen 13. A chest gauge, designated generally by the numeral 14, having the configuration of the gauges shown in FIGS. 2 and 3, is tensioned around the patient's chest 11, while an abdominal gauge designated generally by the numeral 16, also having the configuration of the gauges shown in FIGS. 2 and 3 is tensioned around the patient's abdomen. In other words, the chest gauge 14 is positioned above the patient's diaphragm 12, while the abdominal gauge 16 is positioned below the patient's diaphragm. The gauges 14 and 16 are connected via leads 17 and 18 to a monitoring circuit, designated generally by the numeral 19 and illustrated more specifically in FIG. 8. Referring now to FIG. 2, there is shown one embodiment for the gauges 14 or 16, wherein a silicone rubber tube 20 having a length in the range of 16-36 cm, a wall thickness of 0.003", and an inside diameter of 2 mm is filled with a conductive gel 24 so as to have mechanical and electrical characteristics similar to gauges using a mercury conductor. The tube 20 is sealed at first and second ends 26 and 27 by bronze or gold L-shaped contacts 28 and 29, respectively, which are soldered to standard patient lead wire connectors 31 and 32. Velcro™ pads 33 and 34 are bonded or otherwise connected to the L-shaped contacts 28 and 29 so that the gauges 14 and 16 attach securely about the patient's thorax and abdomen. Referring now to FIG. 3, there is shown an alternative embodiment of the invention, wherein the silicone rubber tubing 20 is arranged in pairs with identical tubes 20A and 20B, each having substantially the same characteristics as the tube 20 of FIG. 2. Gel 24 is a mixture of the following substances: glycerol in the range of about 35-90% by volume and preferably about 40-70% by volume mixed with water; NaCl, from about 20 g per 100 ml by volume to preferably a saturated solution; KCl, from about 20 g per 100 ml by volume to preferably a saturated solution; potassium acetate, from about 20 g per 100 ml by volume to preferably a saturated solution; calcium lactate, from about 20 g per 100 ml by volume to preferably a saturated solution; magnesium sulfate, from about 20 g per 100 ml by volume to preferably a saturated solution; optional ingredients: glucose, 1 g to 50 g per 100 ml by volume and commercial, nontoxic food coloring. A satisfactory method for making the gel is to start with water and to add NaCl to saturation, then add KCl to saturation, K acetate to saturation, calcium lactate to saturation, and, if a gel is desired, magnesium sulfate to saturation. In every instance, saturation is observed by the presence of an undissolved solid phase of the added component. Thereafter, the glycerol is added and, after the volume of glycerol exceeds a value of about 40%, undissolved salts surprisingly enter into the solution, thereby resulting in a system having salt concentrations exceeding those in water alone. It is contemplated that other methods may also be used, e.g., adding the salts to a glycerol-water mixture. In any case, an important inventive aspect of this invention is the discovery of the enhanced salt solubilities due to the presence of glycerol, and it is contemplated that equivalent salt mixtures or even single salts may be used to obtain advantages of the invention. All of the above components are commonly used materials which are available for intravenous fluid preparations and are readily available in sterile form. The solution does not support bacterial growth without glucose. If glucose is included, it is preferred that a mixture be made up in a closed, sterile circuit. Since the mixture is normally a clear gel, the addition of food coloring helps in determining if the contacts are immersed and whether the tube is completely filled with gel so as to preclude air spaces or voids. In addition, since the silicone rubber tubes 14 and 16 have very thin walls, e.g., as low as 0.003 inch, the addition of food coloring indicates whether the walls have been ruptured or whether there has been passage of any of the gel or its constituents through the tubing wall by osmosis. Another advantage of the aforedescribed gel is that it may be stored for an indefinite period without leaking through the tube wall and thereafter serve as a stable transducer for at least a month or more while maintaining impedance below about 80 kohms. Depending on its geometry, the impedance of the gauges 14 and 16 is in the range of 20-60 kohms, with voltage/centimeter remaining substantially constant at different gauge lengths, as is illustrated in FIG. 5. As is seen by extrapolating FIGS. 4A and 4B, the change in impedance with stretch is nearly linear for at least 50% of the length of the gauge. The signal-to-noise ratio is high, with more than 300 mv/cm of stretch when activated by 2-4 volts applied in the range of 500 Hz to 30 kHz. Gauges 14 and 16 are capable of resolving a 0.1 mm change in dimension with a battery-powered circuit. Since the circumferential respiratory excursion for adults is usually less than 6 cm (0.1 mm to 60 mm), the gauge provides a highly accurate indicator of tidal volume. By simultaneous cross-sectional measurements of the patient's thorax or chest 11 with the gauge 14 and the patient's abdomen 13 with the gauge 16, approximations of tidal volume accurate to 0.1 mm of gauge length can be obtained. Since the absolute circumference is known, the variation in circumference can be used to estimate volume based on coefficients determined in vivo by one obstruction performed during inspiration and another performed during expiration. The relationship of tidal volume to circumference is a unique coefficient relating volume to the square of the circumference of the applied gauges 14 and 16. The interaction of the thorax 11 and the abdomen 13 is calculated simultaneously in real time to estimate both tidal volume and functional residual capacity. Since the signal from the gauge provides both absolute circumference and circumference variation to an accuracy of 0.1 mm, an estimate of both functional residual capacity and tidal volume can be developed to a presumed accuracy of a few cubic centimeters. By using the two gauges 14 and 16 in fixed geometry around the patient, an independently calibratable monitor for absolute volume of respiratory effort is provided. The gauges 14 and 16 can be manufactured to tolerances where the impedance is calculable simply by knowing the gauge geometry. Referring now to FIG. 6, there is shown apparatus for performing the calibrating step of the instant invention, wherein gauge 14 or 16 is mounted on an accurate vernier rule 60 by fixing one end 26 thereto and attaching the other end 27 to a sliding element 61 settable to fixed stops. The gauge 14 or 16 is then stretched to measured lengths and the voltage levels indicative of these lengths is entered into the microprocessor 19 (FIGS. 1 and 7) via a standard digital switch. In order to obtain an accurate average signal, the gauge 14 or 16 may be stretched a number of times between fixed stops and the voltages at those stops entered in and averaged by the microprocessor 9. The gauge 14 or 16 is then wrapped around a patient 10 and the separation distance "L" entered in the microprocessor 19 as a correction factor via a digital switch. The distance "L" is added to the lengths of the gauges 14 and 16 so that the total circumference of the patient is taken into account when computing residual capacity and tidal volume of the patient's respiration. By utilizing the aforedescribed gauges 14 and 16, one is able to obtain immediately a reading of absolute volume and need not wait the usual ten minutes for a system using induction loops to average out readings and settle down to a reasonable approximation of volume. Accordingly, the gauges 16 and 17 of the instant invention allow for faster more efficient utilizations of systems such as NMR's and CT's. Referring now to FIG. 7, it is seen that the chest gauge 14 and abdominal gauge 16 are connected to the microprocessor and clock 19. Leads 31 and 31' of the gauges 14 and 16, respectively, are connected through analog-to-digital converters 70 and 70' to the microprocessor and clock 19 via leads 71 and 71'. Leads 32 and 32' are connected to the analog-to-digital converters 70 and 70' via variable resistors Rc and Ra, respectively, and their input is also fed to the microprocessor 19 via lines 71 and 71'. The signals on lines 31 and 31', and 32 and 32' are fed through digital input-output chips 74 and 74' via lines 76 and 76', and 77 and 77', respectively, with the signals on lines 77 and 77' being unmodified by the resistors Rc and Ra in series with the gauges and while changes in pulse amplitude are measured through programmable input amplifiers 80 and 80'. The output of the microprocessor 19 can be displayed by a digital readout 81, or via a digital-to-analog converter 82, recorded on tape or by a polygraph 83. The signal from the digital-to-analog converter 82 may also sound an alarm 84 or be used to enhance NMR or CT scan images 85. Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever. The entire texts of all applications, patents and publications cited herein are hereby incorporated by reference.	An apparatus for measuring respiration includes a first gauge for positioning around a patient's chest and a second gauge for positioning around the patient's abdomen. Each gauge is comprised of a silicone rubber tube filled with a conductive gel. The conductive gel is a composition comprising glycerol, water, and sodium chloride. Upon securing the gauges about the patient, signals indicative of absolute volume are immediately available, providing a new and improved method of measuring and/or monitoring respiration.	7
FIELD OF THE INVENTION The present invention relates generally to angleboard edge protectors for protecting the corner or edge regions of individual packages, fragile articles or products, palletized loads, and the like, and more particularly to a new and improved angleboard edge protector which is uniquely constructed so as to protectively surround or envelop a corner or edge region of an individual package, fragile article or product, palletized load, or the like, yet simultaneously facilitates the reduction in the amount of paper required in order to fabricate the angleboard edge protector without sacrificing the integrity, strength, and protective qualities of the angleboard edge protector. BACKGROUND OF THE INVENTION Package, article, palletized load edge or corner protectors, corner post supports, and the like, are of course well-known in the packaging and shipping industries, and are accordingly widely used in connection with the shipping and transportation of various packages, articles, products, palletized loads, and the like, in order to protect the same during transit, wherein it is particularly desirable to protect the corner or edge portions or regions thereof. Typical or conventional edge or corner protectors, or corner post supports, are disclosed, for example, within U.S. Pat. No. 5,307,928 which issued to Bishop on May 3, 1994, U.S. Pat. No. 5,181,611 which issued to Liebel on Jan. 26, 1993, U.S. Pat. No. 5,175,041 which issued to Webb et al. on Dec. 29, 1992, U.S. Pat. No. 5,161,692 which issued to Knierim on Nov. 10, 1992, U.S. Pat. No. 5,131,541 which issued to Liebel on July.21, 1992, U.S. Pat. No. 5,048,689 which issued to McFarland on Sep. 17, 1991, U.S. Pat. No. 4,771,893 which issued to Liebel on Sep. 20, 1988, U.S. Pat. No. 4,399,915 which issued to Sorenson on Aug. 23, 1983, U.S. Pat. No. 3,955,677 which issued to Collingwood on May 11, 1976, and U.S. Pat. No. 3,536,245 which issued to Palmer on Oct. 27, 1970. All of the aforenoted patented implements are basically similar to each other and representative of conventional corner or edge protectors in that the same comprise two laminated leg structures disposed at 90° with respect to each other so as to effectively define an interior region within which the corner or edge portion, of the particular article, product, package, or palletized load, to be protected is adapted to be disposed. The number of layers of paper, fiber board, corrugated board, or the like, from which the particular edge or corner protector is fabricated, plays an inherent part in determining or predetermining the strength of the particular edge or corner protector, or corner post support. However, it is also well-known in the packaging and shipping industries that the largest cost component inherent in connection with the manufacture of fabrication of the corner or edge protectors is the cost of the paper components per se or raw materials. It would therefore be desirable to substantially reduce the amount of paper raw materials that are required in connection with the manufacture or fabrication of such corner or edge protectors, however, care must be taken so as to ensure that the structural integrity and strength characteristics of the corner or edge protectors are not adversely compromised. A need therefore exists in the art for a new and improved corner or edge protector wherein the amount of paper raw materials that are required in connection with the manufacture or fabrication of corner or edge protectors can be substantially reduced while simultaneously preserving the structural integrity and strength characteristics of each manufacture or fabricated edge or corner protector. OBJECTS OF THE INVENTION Accordingly, it is an object of the present invention to provide a new and improved angleboard edge or corner protector for use in connection with the protection of corner or edge regions of various articles, packages, products, palletized loads, and the like. Another object of the present invention is to provide a new and improved angleboard edge or corner protector for use in connection with the protection of corner or edge regions of various articles, packages, products, palletized loads, and the like, whereby the new and improved angleboard edge or corner protector overcomes the various economic disadvantages characteristic of similar conventional or PRIOR ART edge or corner protectors. An additional object of the present invention is to provide a new and improved angleboard edge or corner protector for use in connection with the protection of corner or edge regions of various articles, packages, products, palletized loads, and the like, wherein the unique and novel structure characteristic of the new and improved angleboard edge or corner protector constructed in accordance with the principles and teachings of the present invention enables edge or corner protector manufacturers to realize or achieve substantial savings in costs incurred in connection with the fabrication or manufacture of the edge or corner protectors. A further object of the present invention is to provide a new and improved angleboard edge or corner protector for use in connection with the protection of corner or edge regions of various articles, packages, products, palletized loads, and the like, wherein the unique and novel structure characteristic of the new and improved angleboard edge or corner protector constructed in accordance with the principles and teachings of the present invention enables edge or corner protector manufacturers to realize or achieve substantial savings in costs incurred in connection with the fabrication or manufacture of the edge or corner protectors as a result of a reduction in the amount of raw material paper that is required to in fact fabricate or manufacture the edge or corner protectors. A last object of the present invention is to provide a new and improved angleboard edge or corner protector for use in connection with the protection of corner or edge regions of various articles, packages, products, palletized loads, and the like, wherein the unique and novel structure characteristic of the new and improved angleboard edge or corner protector constructed in accordance with the principles and teachings of the present invention enables edge or corner protector manufacturers to realize or achieve substantial savings in costs incurred in connection with the fabrication or manufacture of the edge or corner protectors as a result of a reduction in the amount of raw material paper that is required to in fact fabricate or manufacture the edge or corner protectors, and yet, the structural integrity and strength characteristics of the fabricated or manufactured edge or corner protectors are not adversely compromised. SUMMARY OF THE INVENTION The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved edge or corner protector which comprises a predetermined number of plies of paper serially disposed atop each other so as to form a laminate when glued together, and wherein, alternative layers or lamina of the overall laminated edge or corner protector have different width dimensions. More particularly, for example, the edge or corner protector will be fabricated or manufactured from a plurality of alternating paper plies which have alternative width dimensions, and the paper plies are bent at a common central portion through means of an angle of 90° such that the resulting edge or corner protector comprises a common central apex portion and two leg portions disposed at an angle of 90° with respect to each other. The outermost paper plies of the edge or corner protector will have a width dimension of, for example, six inches (6.00″) and the remaining alternating intermediate paper plies will have width dimensions of, for example, three inches (3.00″) and six inches (6.00″). In this manner, the first half or proximal section of each leg portion which is disposed closest to the commmon apex portion of the edge or corner protector will comprise all of the paper plies forming the edge or corner protector whereby such first half or proximal section of each leg portion of the edge or corner protector will have a first predetermined caliper or thickness dimension, whereas the second half or distal section of each leg portion which is disposed furthest from the commmon apex portion of the edge or corner protector will comprise only the widest paper plies forming the edge or corner protector whereby such second half or distal section of each leg portion of the edge or corner protector will have a second predetermined caliper or thickness dimension which is less than the aforenoted first predetermined caliper or thickness dimension characteristic of the first half or proximal section of each leg portion of the edge or corner protector. In this manner, a substantial cost savings in paper raw materials can be achieved or realized while simultaneously preserving the structural integrity and strength characteristics of the edge or corner protector. BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features, and attendant advantages of the present invention will be more fully appreciated from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views, and wherein: FIG. 1 is a schematic illustration, shown upon a relatively enlarged or exaggerated scale, of a new and improved edge or corner protector as constructed in accordance with the principles and teachings of the present invention and showing the cooperative parts thereof comprising the alternating relatively wide and relatively narrow width paper ply components wherein the paper plies have not as yet been glued and compressed together; FIG. 2 is a schematic view corresponding substantially to the view of FIG. 1 showing, however, the new and improved edge or corner protector wherein the paper plies have been glued together but not necessarily compressed together in their finalized form so as to in fact form or define the commercially useable edge or corner protector; and FIG. 3 is a schematic view corresponding substantially to those views of FIGS. 1 and 2 showing, however, the finalized commercial form of the edge or corner protector wherein after compression together of the alternating plies having the different width dimensions, it is relatively difficult to discern the disposition of such alternating paper plies whereby the resulting commercially useable edge or corner protector will exhibit satisfactory structural integrity and strength characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and more particularly to FIGS. 1-3 thereof, a new and improved edge or corner protector, constructed in accordance with the principles and teachings of the present invention, is disclosed and is generally indicated by the reference character 10 . As can best or most clearly be appreciated from FIG. 1, which comprises a view of the new and improved edge or corner protector 10 upon an enlarged or exaggerated scale, it is seen that the new and improved edge or corner protector 10 comprises a first set of paper plies 12 all of which have the same relatively large predetermined width dimension, and a second set of paper plies 14 all of which have the same relatively small predetermined width dimension. It is further appreciated that the first set of paper plies 12 and the second set of paper plies 14 are substantially disposed in an overlapped, alternating mode, and that all of the paper plies comprising the first and second sets of paper plies 12 , 14 are bent at a central portion thereof, as considered in the widthwise direction, such that a first half of the paper plies 12 and a first half of the paper plies 14 together define a first leg 16 of the new and improved edge or corner protector 10 , while a second half of the paper plies 12 and a second half of the paper plies 14 together define a second leg 18 of the new and improved edge or corner protector 10 . An apex or corner region 20 is defined at the common bend point or line of each one of the first and second sets of paper plies 12 , 14 such that the first and second legs 16 , 18 are disposed at an angle of 90° with respect to each other. In accordance with current or conventional techniques utilized in connection with the manufacture or fabrication of edge or corner protectors, the individual paper plies that comprise such conventional or PRIOR ART edge or corner protectors have predetermined width dimensions. Accordingly, in accordance with the techniques utilized in connection with the manufacture or fabrication of the new and improved edge or corner protector 10 comprising the present invention, each one of the paper plies 12 utilized within the first set of paper plies, as well as each one of the paper plies 14 utilized within the second set of paper plies will comprise a paper ply having one of the standard or conventional predetermined width dimensions. The critical importance or significance of the unique and novel structure characterized by means of the edge or corner protector 10 of the present invention resides in the use of paper plies having at least two different width dimensions. It is initially and additionally noted that while the new and improved edge or corner protector 10 of the present invention is illustrated as comprising, for example, only two sets of paper plies 12 , 14 having two different width dimensions, an edge or corner protector, constructed in accordance with the principles and teachings of the present invention, could comprise, for example, three or more sets of paper plies having three or more different width dimensions. It is further noted that the reasons for utilizing the different sets of paper plies comprising the different width dimensions are several, and in addition, they are all operatively or functionally interrelated. Firstly, for example, it is known that an edge or corner protector must have a predetermined thickness or number of paper plies within the corner or apex region thereof in order to in fact provide or exhibit the requisite amount of protection and cushioning functions, as well as strength, required in connection with the protection of an edge or corner region of an article, product, package, or palletized load when the edge or corner protector is applied to or secured upon the particular article, product, package, or palletized load. Secondly, the overall width dimension of the edge or corner protector must be sufficient so as to facilitate the handling of the edge or corner protector and the orientation and positioning of the same with respect to and upon the edge or corner region of the particular article, product, package, or palletized load. Thirdly, it has been recognized and appreciated that the single largest cost incurred in connection with the manufacture or fabrication of edge or corner protectors comprises the cost of the raw material paper plies. Accordingly, it would be desirable to significantly reduce such manufacturing or fabricating costs by effectively reducing the overall amount of paper comprising a single edge or corner protector if such could in fact be achieved without, obviously, adversely affecting the structural integrity, strength, and protection properties of the edge or corner protector. As a result of the unique and novel structure comprising the edge or corner protector 10 of the present invention, the aforenoted objectives have in fact been achieved. More particularly, by constructing the edge or corner protector 10 in accordance with the principles and teachings as illustrated, for example, within FIG. 1, wherein the relatively narrow set of paper plies 14 have been used in conjunction with the relatively wide set of paper plies 12 in an alternating or interdigitated manner, it is seen, for example, that a relatively thick region of the edge or corner protector 10 is defined within the vicinity of the apex portion 20 . In particular, such apex portion 20 , as well as the regions disposed immediately upon opposite sides thereof, is comprised of seven plies of paper as comprising the first and second sets of paper plies 12 , 14 . It is of course to be noted that the precise number of paper plies, comprising the apex region 20 and those regions disposed immediately upon the opposite sides thereof, is not to be limited to seven. The important factor concerning the structure of the edge or corner protector 10 resides in the fact that the apex portion 20 , as well as the regions disposed immediately upon the opposite sides thereof, is comprised of the maximum number of paper plies comprising the edge or corner protector 10 , and in this manner, the maximum protection, cushioning, and strength characteristics are exhibited within the apex portion 20 , as well as the regions disposed immediately upon the opposite sides thereof, so as to in fact afford the maximum protection to the edge or corner region of the particular article, product, package, or palletized load being protected. Continuing further, as a result of those distal portions of each leg member 16 , 18 of the edge or corner protector 10 , which are remote from the apex portion 20 , being structurally defined in effect solely by means of the relatively wide first set of paper plies 12 , although the protection, cushioning, and strength characteristics within such distal regions are not maximized as are such characteristics within the apex portion 20 and those proximal regions disposed immediately upon opposite sides of the apex portion 20 , the need for such maximized characteristics within such distal regions, which are effectively removed from the apex, edge, or corner regions of the article, product, package, or palletized load, is not as great. What is important however, and what is nevertheless provided by means of the edge or corner protector 10 of the present invention as a result of the use of the relatively wide paper plies 12 , is the provision to the edge or corner protector 10 of a sufficient overall width dimension which facilitates the handling, orientation, and positioning of the edge or corner protector upon the edge or corner region of the article, product, package, or palletized load prior to and in preparation for the fixed securement of the edge or corner protector upon the article, product, package, or palletized load by means of, for example, metal or plastic strapping, shrink or stretch wrapping, or the like. Lastly, as a result of the aforenoted structure comprising the edge or corner protector 10 constructed in accordance with the principles and teachings of the present invention, a significant reduction in raw material paper costs is able to be achieved. For example, if each one of the paper plies comprising the first set of paper plies 12 has a width dimension of six inches (6.00″), and if each one of the paper plies comprising the second set of paper plies 14 has a width dimension of three inches (3.00″), then a paper cost savings of approximately twenty-five percent (25%) is able to be achieved. If, for example, each one of the paper plies comprising the second set of paper plies 14 has a width dimension of four inches (4.00″), then a paper cost savings of approximately seventeen percent (17%) is able to be achieved. It is to be further appreciated that the edge or corner protector 10 can be manufactured or fabricated from the aforenoted at least two sets of paper plies 12 , 14 having at least two different width dimensions wherein the particular width dimensions of either one of the first and second sets of paper plies 12 , 14 may vary as exemplified by means of the following examples: EXAMPLE 1 Width Dimension of Each Paper Ply Comprising 6.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 5.00 Inches The Second Set of Paper Plies 14: EXAMPLE 2 Width Dimension of Each Paper Ply Comprising 6.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 4.00 Inches The Second Set of Paper Plies 14: EXAMPLE 3 Width Dimension of Each Paper Ply Comprising 6.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 3.00 Inches The Second Set of Paper Plies 14: EXAMPLE 4 Width Dimension of Each Paper Ply Comprising 6.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 2.00 Inches The Second Set of Paper Plies 14: EXAMPLE 5 Width Dimension of Each Paper Ply Comprising 5.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 4.00 Inches The Second Set of Paper Plies 14: EXAMPLE 6 Width Dimension of Each Paper Ply Comprising 5.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 3.00 Inches The Second Set of Paper Plies 14: EXAMPLE 7 Width Dimension of Each Paper Ply Comprising 5.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 2.00 Inches The Second Set of Paper Plies 14: EXAMPLE 8 Width Dimension of Each Paper Ply Comprising 4.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 3.00 Inches The Second Set of Paper Plies 14: EXAMPLE 9 Width Dimension of Each Paper Ply Comprising 4.00 Inches The First Set of Paper Plies 12: Width Dimension of Each Paper Ply Comprising 2.00 Inches The Second Set of Paper Plies 14: With reference now being made specifically to FIGS. 2 and 3, it is lastly noted that in connection with the actual manufacture or fabrication of the edge or corner protector 10 , the entire outer peripheral surface of the edge or corner protector 10 is adapted to be wrapped within an outer wrapping layer 22 , and the outer wrapping layer 22 , as well as the individual paper plies 12 , 14 , are adapted to be glued together so as to form the integral composite edge or corner protector 10 . As shown in FIG. 2, for example, the various paper plies comprising the first and second sets of paper plies 12 , 14 are shown in their relative states before being compressed together, whereas as shown in FIG. 3, the first and second sets of paper plies 12 , 14 are shown in the their relative states after being compressed together whereby, once the first and second sets of paper plies 12 , 14 are in fact compressed together, it is difficult to discern the individual paper plies comprising the first and second sets of paper plies 12 , 14 . Accordingly, all of the paper plies comprising the first and second sets of paper plies 12 , 14 together form, in effect, an integrated one-piece edge or corner protector structure. It is additionally noted that when the first and second sets of paper plies 12 , 14 , together with the outer wrapping layer 22 , are compressed together, the leg portions 16 , 18 of the edge or corner protector 10 will exhibit predetermined thickness dimensions within those regions adjacent to the apex portion 20 as well as within the distal tip regions of the leg portions 16 , 18 as denoted by the thickness dimensions T and t, respectively. More particularly, exemplary thickness dimensions T,t may be as follows: EXAMPLE 10 Maximum Thickness T Within Proximal 0.250 Inches Regions of Each Leg Portion 16, 18 Minimum Thickness t Within Distal 0.125 Inches Tip Regions of Each Leg Portion 16, 18 EXAMPLE 11 Maximum Thickness T Within Proximal 0.225 Inches Regions of Each Leg Portion 16, 18 Minimum Thickness t Within Distal 0.120 Inches Tip Regions of Each Leg Portion 16, 18 EXAMPLE 12 Maximum Thickness T Within Proximal 0.200 Inches Regions of Each Leg Portion 16, 18 Minimum Thickness t Within Distal 0.110 Inches Tip Regions of Each Leg Portion 16, 18 EXAMPLE 13 Maximum Thickness T Within Proximal 0.180 Inches Regions of Each Leg Portion 16, 18 Minimum Thickness t Within Distal 0.100 Inches Tip Regions of Each Leg Portion 16, 18 EXAMPLE 14 Maximum Thickness T Within Proximal 0.160 Inches Regions of Each Leg Portion 16, 18 Minimum Thickness t Within Distal 0.080 Inches Tip Regions of Each Leg Portion 16, 18 Thus, it may be seen that in accordance with the principles and teachings of the present invention, there has been provided a new and improved edge or corner protector which substantially reduces the overall cost of fabrication or manufacture of the edge or corner protector by substantially reducing the amount of paper raw material required to be incorporated within the new and improved edge or corner protector without adversely affecting the protection, cushioning, strength, and structural integrity characteristics of the edge or corner protector and yet facilitating the handling, positioning, and orientation of the edge or corner protector upon a particular article, product, package, or palletized load. More particularly, the new and improved edge or corner protector comprises the use of two sets of paper plies characterized by two different width dimension values wherein both sets of paper plies are in effect present within the proximal apex corner portion of the edge or corner protector so as to provide the necessary protection to the edge or corner region of the particular article, product, package, or palletized load being protected, while only the wider width dimensioned paper plies are disposed within the distal regions of the leg members of the edge or corner protector so as to provide the edge or corner protector with the necessary width dimension in order to enable or facilitate the proper handling, orientation, and positioning of the edge or corner protector upon an edge or corner region of an article, product, package, or palletized load to be protected. Obviously, many variations and modifications of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.	An edge or corner protector comprises an apex portion and a pair of leg members extending away from the apex portion so as to define an angle of approximately 90° therebetween. The apex portion and leg members are defined by a plurality of paper plies which have at least two different width dimensions. Relatively narrow and relatively broad paper plies are alternatively arranged with respect to each other whereby the apex portion and proximal portions of the leg members are formed by both the broad and narrow paper plies whereas distal portions of the leg members are formed only by the broad paper plies. In this manner, increased thickness and strength is provided within the apex and proximal portions of the leg members as needed, the distal portions of the leg members nevertheless facilitate mounting, positioning, and orientation of the edge or corner protectors upon edge or corner regions of articles to be protected, and a substantial reduction in the overall raw material cost is achieved.	1
TECHNICAL FIELD This invention relates to compounds of the general formula [I], ##STR6## wherein R 1 is hydrogen, hydroxy, lower alkyl or lower alkoxy; ##STR7## R 2 is hydrogen, benzoyl or ##STR8## R 3 is hydroxy, lower alkoxy, --NHOH or ##STR9## R 4 is R 5 is hydrogen or halogen; R 6 and R 7 each is hydrogen or lower alkyl; Z is straight or branched alkylene containing 1 to 3 carbon atoms; ##STR10## when R 3 is hydroxy or lower alkoxy, R 2 is and salts thereof, said lower alkyl and lower alkoxy groups contain 1 to 6 carbon atoms. The same shall be applied hereinafter. BACKGROUND OF THE TECHNICAL FIELD Thiazolidine derivatives having mercapto group are useful compounds as antihypertensive agents. It is known that particularly the compound of the formula [II], which is the basic structure of the compounds of this invention, shows an excellent antihypertensive effect (Japanese patent application No. 49657/1978). ##STR11## DESCRIPTION OF THE INVENTION This invention relates to novel thiazolidine derivatives. We found that the prolongation of the activity and stability of the compound were accomplished by conversion of mercapto group and/or carboxy group of the compound of the formual [II], which shows an antihypertensive effect, into suitable derivatives shown in this invention. Substituents of the compound [I] of this invention are as follows. Lower alkyl is alkyl group having 1 to 6 carbon atoms, for example methyl, ethyl, hexyl or isobutyl, lower alkoxy is alkoxy group having 1 to 6 carbon atoms, for example methoxy, ethoxy, t-butoxy or hexyloxy, and halogen is fluorine, chlorine or bromine. The compounds [I] of this invention are synthesized by the following procedures. The compound of the formula [V] is obtained by condensation of the compound of the formula [III] with the compound of the formula [IV] by the known method such as Shotten-Baumann method, mixed anhydride method, etc. ##STR12## wherein R 8 is hydroxy or lower alkoxy; R 9 is R 2 except hydrogen; X is halogen or hydroxy. The same shall be applied hereinafter. The compound of the formula [VII] is obtained by condensation of the compound of the formula [V] with the compound of the formula [VI] by the known method such as mixed anhydride method etc. ##STR13## wherein ##STR14## R 10 is hydroxy or The same shall be applied hereinafter. The compound of the formula [I] wherein R 2 is hydrogen is obtained by hydrolysis by acid, alkaline, etc. The compound of the formula [I] prepared by the above methods can form the conventional salts to be generally used as medicine such as sodium salt, potassium salt, calcium salt, magnesium salt, aluminum salt, ammonium salt, diethylamine salt, triethanolamine salt, etc. The compound of the formula [I] has two or more asymmetric carbon atoms, so it has the stereoisomers, which are within the limit of this invention. Pharmacological test, acute toxicity test and examples of formulation are shown as below. PHARMACOLOGICAL EXPERIMENT Male spontaneously hypertensive rats (Charles River) weighing 370-430 g (37-43 weeks of age) were used. The subject compound, suspended in 0.5% tragacanth, was given orally to the animals. Their blood pressure was measured by indirect tail-cuff method using a programmed electrosphygmomanometer. EXPERIMENTAL RESULTS The FIG. 1 shows the time course of the hypotensive effect in spontaneously hypertensive rats by oral administration of (2R,4R)--3--[S--4--(dipropylsulfamoyl)benzoyl]--3--mercapto--propionyl]--2--(2-hydroxyphenyl)--4--thiazolidinecarboxylic acid (Example 1) as a representative of the compounds of this invention and of (2R,4R)--2--(2-hydroxyphenyl)--3--(3--mercaptopropionyl)--4--thiazolidinecarboxylic acid as a control compound. The abscissa of the figure shows the time after administration and the ordinate shows the blood pressure in mmHg having decreased by the administration. In the figure, line 1 and line 2 represent the hypotensive effect by the compound of this invention at doses of 30 mg/Kg and 10 mg/Kg, respectively, line 3 that by the reference compound at a dose of 30 mg/Kg, and line 4 control (no drugs). The compound of this invention clearly decreased the blood pressure in spontaneously hypertensive rats at doses of 10 mg/Kg and 30 mg/Kg. It is found from the above pharmacological experiments that the compounds [I] of this invention are useful as the antihypertensive agents with a long-lasting effect. The compounds can be administered either orally or parenterally. The dosage forms are tablet, capsule, granule, powder, suppository, injection, etc. For the treatment of hypertension, these preparations can contain not only general excipients but also other antihypertensive agents such as reserpine, α-methyldopa, guanethidine, chlonidine, hydralazine, etc. The dose is adjusted depending on symptoms, dosage forms, etc., but usual daily dosage is 1 to 5000 mg, preferably 10 to 1000 mg, in one or a few divided doses. ACUTE TOXICITY TEST Acute toxicity of (2R,4R)--3--[S--[4--(dipropylsulfamoyl)--benzoyl]--3--mercaptopropionyl]--2--(2--hydroxyphenyl)--4--thiazolidinecarboxylic acid is shown in the table. TABLE______________________________________Route of administration LD.sub.50______________________________________oral.sup.1 No death was observed by the continuous administration of 1000 mg/Kg for one week.intravenous.sup.2 >500 mg/Kg______________________________________ .sup.1 administered as tragacanth .sup.2 administered as aqueous sodium hydroxide solution Animals used in this test were ten male mice in each route. From the above table, it is clear that the compound of this invention shows low toxicity. The followings show the examples of the formulation. (1) Oral drug ______________________________________(a) tabletcompound A* 30 mglactose 150 mgcrystalline cellulose 50 mgcalcium carboxymethylcellulose 7 mgmagnesium stearate 3 mgTotal 240 mgcompound A 150 mglactose 60 mgcrystalline cellulose 30 mgcalcium carboxymethylcellulose 7 mgmagnesium stearate 3 mgTotal 250 mg______________________________________ Compound A of this invention: (2R,4R)3-[S[4Dipropylsulfamoyl)benzoyl3-mercaptopropionyl2-(2-hydroxyphenl)-4-thiazolidinecarboxylic acid The tablets may be treated with common film-coating and further with sugar-coating. ______________________________________(b) granulecompound A 30 mgpolyvinylpyrrolidone 25 mglactose 385 mghydroxypropylcellulose 50 mgtalc 10 mgTotal 500 mg(c) powdercompound A 30 mglactose 500 mgstarch 440 mgcolloidal silica 30 mgTotal 1000 mgcompound A 300 mglactose 230 mgstarch 440 mgcolloidal silica 30 mgTotal 1000 mg(d) capsulecompound A 30 mglactose 102 mgcrystalline cellulose 56 mgcolloidal silica 2 mgTotal 190 mgcompound A 30 mgglycerin 349.98 mgbutyl p-hydroxybenzoate 0.02 mgTotal 380 mg______________________________________ (2) Injection 1 to 30 mg of compound A is contained in 1 ml of the aqueous solution (ph 6.5-7.0). SHORT EXPLANATION OF DRAWING The graphs of FIG. 1 show the antihypertensive effect of the compound of this invention. In the figure, line 1 is the effect produced by 30 mg/Kg of compound A of this invention; line 2, by 10 mg/Kg of compound A; line 3, by 30 mg/Kg of the reference compound; and line 4, by control. BEST MODE OF MAKING THE INVENTION Example 1 (2R,4R)--3--[S--[4--(Dipropylsulfamoyl)benzoyl]--3--mercaptopropionyl]--2--(2--hydroxyphenyl)--4--thiazolidinecarboxilic acid 9.7 g of (2R,4R)--2--(2--hydroxyphenyl) --3--(3--mercaptopropionyl)--4--thiazolidinecarboxylic acid and 12.9 g of potassium carbonate are dissolved in 80 ml of water, and 40 ml of ethyl ether solution of 9.4 g of 4--(dipropylsulfamoyl)benzoyl chloride is added dropwise under ice-cooling. After the addition the reaction mixture is stirred for 1 hour under ice-cooling and for another 1 hour at room temperature. Ether is removed in vacuo and residual solution is adjusted to pH 1 with 6N hydrochloric acid. Produced oily residue is extracted with ethyl acetate. The organic layer is washed with water and dried over anhydrous magnesium sulfate and concentrated in vacuo. The resulting residue is purified by silica gel column chromatography to give 10.5 g of the titled compound as amorphous powder. [α] D 24 +100.6° (c=1.1, methanol). IR (KBr, cm - 1) 3370 (--OH), (--COOH), 1650 (--NCO--), 915 (--SCOph). NMR (CDCl 3 ,δ) 0.85 (6H, t, J=7.0Hz, C--CH 3 ×2), 1.18-2.00 (4H, m, --CH 2 --×2), 3.10 (4H, t, J=7.0Hz, --CH 2 --×2), 2.00-4.00 (6H, m, --CH 2 CH 2 --and C 5 --H 2 ), 4.98 (1H, t, J=6.5Hz, C 4 --H), 6.32 (1H, s, C 2 --H), 6.51-7.13 (3H, m, aromatic H), 7.50-8.15 (5H, m, aromatic H), 8.50-9.50 (2H, br s, --OH and --CO 2 H) Example 2 (2R,4R)--3--[S--[4--Benzylsulfonylamino)benzoyl]--3--mercaptopropionyl]--2--(2--hydroxyphenyl)--4--thiazolidinecarboxylic acid By using 12.9 g of (2R,4R)--2--(2--hydroxyphenyl)--3--mercaptopropionyl) --4--thiazolidinecarboxylic acid and 9.3 g of 4--(benzylsulfonylamino)benzoyl chloride in the same procedures as Example 1, 10.9 g of the titled compound is obtained. mp 121-124°C. (ethonol-water, dec.). [α] D 26 +114.7°(c=0.8, methanol). IR 1735 (--COOH), 1630 (--NCO--, --SCO--), 1600 (C═C), 910 (--SCOph). NMR (DMSO--d 6 ,δ)2.97-3.63 (6H, m, --CH 2 CH 2 --and C 5 --H 2 ), 4.47 (2H, s, --CH 2 --), 4.82 (1H, t, J=8.0Hz, C 4 H), 6.40 (1H, s, C 2 --H), 6.63-8.13 (13H, m, aromatic H), 8.23-10.50 (3H, m, --OH, --CO 2 H and --NH--). Example 3 (2R,4R) --3--(S--Benzoyl--3--mercaptopropionyl)--2--(2--hydroxyphenyl)--4--thiazolidinecarbohydroxamic acid 3.1 g of N--methylmorpholine is added to 180 ml of dry tetrahydrofuran solution of 12.5 g of (2R,4R)--3--(S--benzoyl--3--mercaptopropionyl) --2--(2--hydroxyphenyl)--4--thiazolidine--carboxylic acid. To the reaction mixture, 4.1 g of isobutyl chlorocarbonate is added dropwise while stirring under ice-cooling and further stirred for 30 minutes at the same temperature. To this suspension, 120 ml of methanol solution containing 6.3 g of hydroxylamine hydrochloride and 3.6 g of sodium hydroxide is added dropwise, and stirred for 2 hours by gradually restoring the room temperature. The solvent is removed in vacuo, and N hydrochloric acid is added to the resulting residue. Separated oil is extracted with ethyl acetate, and the organic layer is washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent is removed in vacuo and the resulting oily residue is purified by silica gel coulumn chromatography to give 6.0 g of the titled compound. mp 105-110° C. (amorphous powder, dec.). [α] D 25 +159.6°(c=1.1, methanol). IR (nujol, cm -1 ) 3200 (--OH), 1650 (SCO), 1625 (--NCO--), 912 (--SCOPh). NMR (DMSO--d 6 , δ) 3.13 (6H, m, --CH 2 CH 2 --and C 5 --H 2 ), 4.47 (1H, t, J=8.0Hz, C 4 --H), 6.27 (1H, s, C 2 --H), 6.50-8.00 (8H, m, aromatic H), 8.20 (1H, d, J=6.0Hz, aromatich H), 8.93 (1H, br s, --CONH--), 9.72 (1H, br s, --OH), 10.70 (1H, br s, N--OH). Example 4 (2R,4R)--2--(2--Hydroxyphenyl)--3--(3--mercaptopropionyl)--4--thiazolidinecarbohydroxamic acid 60 ml of concentrated ammonia water is added to 50 ml of methanol solution of 4.3 g of (2R,4R)--3--(S--benzoyl--3--mecaptopropionyl) --2--(2--hydroxyphenyl)--4--thiazolidinecarbohydroxamic acid, and stirred for 1.5 hours at room temperature. Ammonia and methanol are removed in vacuo and extracted with ethyl acetate. The aqueous layer is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated in vacuo. The resulting oily residue is purified by silica gel column chromatography to give 2.0 g of the titled compound. mp 90°-96°C. (amorphous powder, dec.). [α] D 25 +184.3°(c=0.8, methanol). IR (nujol, cm -1 ) 3200 (OH), 1630 (NCO). NMR (DMSO--d 6 , δ) 2.50-3.17 (6H, m, --CH 2 CH 2 --and C 5 --H 2 ), 4.47 (1H, t, J=8.0Hz, C 4 --H), 6.27 (1H, s, C 2 --H), 6.80 (3H, m, aromatic H), 8.20 (1H, d, J=6.0Hz, aromatic H), 9.00 (1H, br s, --CONH), 9.70 (1H, br s, OH), 10.63 (1H, br s, N--OH). Example 5 1--[N--[(2R,4R)--[3--(S--Benzoyl--3--mercaptopropionyl)--2--(2--hydroxyphenyl)--4--thiazolidinyl]carbonyl]hydrazino]phtharazine hydrochloride. By using 12.5 g of (2R,4R)--3--(S--benzoyl--3--mercaptopropionyl) --2--(2--hydroxyphenyl)--4--thiazolidinecarboxylic acid and 5.9 g of hydrarazine hydrochloride in the same procedures as Example 3, 8.9 g of the titled compound is obtained. mp 164°-168°C. (ethyl acetate, dec.). [α] D 24 +120.5°(c=1.0, methanol). IR 1655 (SCO), 1630 (NCO), 1598 (C═C), 910 (SCOPh). NMR (DMSO--d 6 ,δ) 2.90-3.08 (6H, m, --CH 2 CH 2 --and C 5 --H 2 ), 4.82-5.30 (1H, m, C 4 --H), 6.30 (1H, s, C 2--H ), 6.48-7.02 (3H, m, aromatic H), 7.27-7.98 (10H, m, aromatic H), 8.08 (1H, d, J=7.0Hz, aromatic H), 8.43 (1H, s, --OH), 8.55 (2H, m, --NHNH--). cl Example 6 1--[N--[(2R,4R)--2--[2--(2--Hydroxyphenyl)--3--(3--mercaptopropionyl) --4--thiazolidinyl]carbonyl]hydrazino]phtharazine By using 6.0 g of 1--[N--[(2R,4R)--[3--(S--benzoyl--3--mercaptopropionyl) --2--(2--hydroxyphenyl)--4--thiazolidinyl]carbonyl]--hydrazino]phtharazine hydrochloride and 60 ml of concentrated ammonia water in the same procedures as Example 4, 2.4 g of the titled compound is obtained. mp 142°-144°C. (ethyl acetate, dec.). [α] D 26 + 91.5°(c=0.6, methanol). IR 1630 (NCO), 1598 (C═C). NMR (DMSO--d 6 , δ) 1.75-2.25 (1H, m, --SH), 2.25-2.98 (4H, m, --CH 2 CH 2 --), 3.08-3.75 (2H, m, C 5 --H 2 ), 4.77 (1H, t, J=9.4Hz, C 4 --H), 6.38 (1H, s, C 2 --H), 6.58-8.55 (9H, m, aromatic H), 9.25-10.47 (3H, br s, --NHNH--and --OH). UTILITY IN AN INDUSTRIAL FIELD The compounds of this invention are novel compounds which are useful therapeutic agent.	This invention relates to the compound of the general formula [I], process for preparing the compound and antihypertensive agent containing the compound as a main ingredient. ##STR1## wherein R 1 is hydrogen, hydroxy, lower alkyl or lower alkoxy; R 2 is hydrogen, benzoyl or ##STR2## R 3 is hydroxy, lower alkoxy, --NHOH or ##STR3## R 4 is ##STR4## R 5 is hydrogen or halogen; R 6 and R 7 each is hydrogen or lower alkyl; Z is straight or branched alkylene containing 1 to 3 carbon atoms; when R 3 is hydroxy or lower alkoxy, R 2 is ##STR5## and salts thereof, said lower alkyl and lower alkoxy groups contain 1 to 6 carbon atoms.	2
This is a continuation of co-pending application Ser. No. 235,482 filed on Aug. 24, 1988, now abandoned. FIELD OF THE INVENTION This invention relates generally to a pipe seal or gasket and particularly to a seal which encircles a pipe inserted into a wall of another pipe of larger diameter or the wall of a container, the seal or gasket being compressed between the pipe and the wall to ensure leak-proof assembly. BACKGROUND OF THE INVENTION It has long been a desire to develop a simple seal which obviates the need for the application of additional materials, such as cements or caulking, to prevent the seepage of fluid at points where pipes extend into container walls or into walls of pipes of larger diameter. Such a need has become greater with the development of synthetic materials from which piping or tubing is manufactured. Such materials are economic to make and are easy to work with, but have created vastly different sealing and seepage-prevention problems. Efforts have been made in the past to overcome the seepage problems. SUMMARY OF THE INVENTION The present invention overcomes the prior shortcomings by the provision of a seal, or gasket, with varying degrees of thicknesses in that portion of the seal which is inserted and positioned between the piping and the wall into which the pipe is inserted. Due to this structure, the gasket of this invention stretches and expands around the edges to be sealed, thereby perfecting the seal and ensuring against leakage. An additional advantage of this seal is that such structure creates a much stronger seal, thereby preventing loosening of the seal and acting to make removal of the pipe more difficult. A further advantage of this seal is that such a structure creates a much tighter seal than heretofore possible, thereby preventing wobble or vibration and subsequent loosening of the seal. BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention, illustrated by way of example in the accompanying drawings in which: FIG. 1 is a perspective view of a pipe seal embodying the present invention and positioned adjacent a wall opening into which it will be inserted; FIG. 2 is a perspective view, in partial section, of the pipe seal positioned within the wall opening; FIG. 3 is a vertical cross-sectional view taken along line 3--3 of FIG. 1; FIG. 4 is a vertical cross-section view taken along line 5--5 of FIG. 2, but illustrating a pipe partially inserted into the seal of this invention; and FIG. 5 is a vertical cross-sectional view similar to that shown in FIG. 4, illustrating the distortion of the seal when it is assembled in a wall with a pipe fully inserted and extending therethrough. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is illustrated and will be described as applied to an opening in and insertion into a flat wall configuration, but it has been applied in practice to the side wall of a pipe of larger diameter or to a container having a cylindrical or arcuate side wall configuration, and it will be understood that it works equally well in each of these environments. Accordingly, the illustrations are not intended to be, nor should they be construed to be, a limitation on the invention. The seal of this invention is generally referred to by the numeral 10. As best illustrated in FIG. 3, it will be observed that the interior and exterior peripheral circumferences of the seal are of varying diameters. Outer lip portion 12 of seal 10 is of a larger diameter, preventing the seal from being pushed completely through wall 40 when the pipe is inserted, and is a standard configuration for seals of this nature. It should also be understood that a complete line of seals of a variety of diameters, made to accommodate the variety of diameters in piping, can be provided and nothing herein should be construed as a size limitation. The initial peripheral diameter ID-1 at throat 14 of seal 10 which is encountered by the pipe when the seal is entered (from the left in the illustrations) is somewhat in excess of the diameter of pipe 50, merely to facilitate insertion. The interior diameter of seal 10 is tapered inwardly in distinct sections, each taper being of a different and distinct angle. The outermost peripheral interior diameter ID-2 at throat portion 18 of middle taper 16 approximates the diameter of a pipe to which seal 10 is mated. The axial length of middle taper 16 should exceed the thickness of wall 40. Indeed, the distance from the plane of face 26 of outer lip 12 to the furthermost end 20 of middle taper 16 should be equal to or be slightly in excess of the thickness of wall 40. The rearmost taper 22 of seal 10 is further constricted from interior peripheral diameter ID-3 to the rearmost interior peripheral diameter ID-4. The angle of taper 22 is about 11 degrees. In testing it has been determined that merely forming the interior periphery of a seal to be of a diameter less than that of the inserted pipe will not achieve the desired result. Although a single taper from the outermost radial interior periphery to the innermost radial interior periphery may be satisfactory in some applications, the sharper rearmost taper 22 has been found to more effectively achieve the desired seal. It has also been determined that the thickness of the seal may be varied within reason to accommodate different diameter pipes inserted into the same diameter holes without departing from the invention. The critical feature is the relative taper of peripheral exterior 30 and tapers 16 and 22 rather than the thickness of the walls of seal 10. In other words, by way of further explanation and for exemplary purposes only, there may be a need to insert both a 3/4 inch pipe and a one inch pipe into a single container or wall. The holes to receive each pipe may be drilled on site to a diameter of 11/4 inches. One of the seals may have an outermost peripheral interior diameter ID-2 at throat portion 18 of 3/4 inches and another seal may have an outermost peripheral interior diameter ID-2 at throat portion 18 of one inch. The outer peripheral diameter of both seals, at lip face 26, will be the diameter of the hole, that is, 11/4 inches. The result is that at lip 26, the thickness of wall 34 of seal 10, in the first instance, will be approximately 1/4 inch, while in the second instance it will be approximately 1/8 inch. The point being that the thickness of the wall of the seal, within reason, is not so critical as is the differential in the relative tapers of the exterior and interior walls in the axial direction. If, however, the wall is too thick, the effectiveness of the seal will be lost because the compression will be internally absorbed. The peripheral exterior 30 of seal 10, from face 26 of lip portion 12 to the rearmost edge 28 of seal 10, is slightly axially tapered. At the base of 26 the outer peripheral diameter approximates or very slightly exceeds, but preferably should not be less than the diameter of opening 38 of wall 40. At the rearmost edge 28 of seal 10, there is a flange or lip 32 which has an external peripheral diameter in excess of the diameter of hole 38. This is merely a safety feature which serves to prevent inadvertent dislodging of seal 10 between the time that it is inserted into hole 38 and the time that pipe 50 is extended therethrough. It has been determined that the axial taper of outer periphery 30 of seal 10 should be less than the axial taper along the interior periphery of the middle taper 16. Ideally, the preferred degree of taper of outer periphery 30 will be one-half the degree of taper of the inner periphery. More precisely, the preferred degree of taper for inner and outer peripheries will be 6 degrees and 3 degrees respectively. Seal 10 is fabricated of any resilient material commonly used for the intended purpose. Normally, such a seal is molded of a semi-elastic, semi-plastic rubber-like composition which possesses a certain degree of rigidity, but which is stretchable and pliable. In operation, as illustrated in FIGS. 1 and 2, wall 40 is provided with hole 38 of a desired diameter to snugly receive seal 10. Seal 10 is then inserted into hole 38 of wall 40, face 26 of lip portion 12 abutting the face of wall 40. It will be understood that the hole 38 is generally drilled on site and that the resulting edge is not of the accuracy and fineness which is obtained from a sophisticated machine operation. Such an edge, or the cut, contains imperfections and it is one of the benefits and objectives of this invention to overcome and to seal such imperfections. Referring to FIG. 4, it will be seen that pipe 50 has been partially inserted through seal 10 and into wall 40. More specifically, the end of pipe 50 has reached the furthermost end 20 of middle taper 16. Due to this taper, that part of the seal along the peripheral exterior 30 is axially stretched in a rearward direction, as shown by arrows 44 in FIG. 4, and forced outwardly into a snug contact with the inner diameter of hole 38. In application, any slight imperfections in the cut or a slightly off-round configuration is filled with the material of which seal 10 is composed. As pipe 50 is inserted farther into and through seal 10, rearmost taper 22, with its excess of material, comes into play. This tapered material functions in two distinct ways. It will be recalled that the thickness of the wall of seal 10 at the rearmost portion 20 (ID-3) of middle taper 16 is greater than the thickness of the seal wall at face 26. As pipe 50 is inserted beyond middle taper 16, generally corresponding to inner edge 42 of wall 40, the material is stretched and forced rearwardly and outwardly, as depicted by arrows 46 in FIG. 5, to actually form a lip 48 around the entire inner periphery of hole 38 in wall 40. The material is squeezed to such an extent that it bulges into and around hole 38. Thus, the seal is perfected. Due to the thickness of the rearmost wall of seal 10 relative to its thickness adjacent face 26, rearmost portion 28 is stretched rearwardly and outwardly as it is mushroomed against inner edge 42 of wall 40. As a result, pipe 50 is tightly grasped by seal 10, to such an extent that pipe 50 cannot easily be removed from wall 40. Further, this prevents the pipe from wobbling and ensures that it will not become loosened due to vibrations or the like. While the preferred embodiment of this invention has been illustrated and described, it will be understood that changes in the structure may be made within the scope of the appended claims without departing from the spirit of the invention.	An improved seal at the junction of a pipe or tube to an opening formed in a flat wall or in the wall of a cylindrical or rounded container, including axially tapered exterior and interior peripheral surfaces. The tapers of such surfaces being different one from the other and being of such a degree that, when the seal is inserted into the opening in the receiving member and the pipe is inserted therethrough, the material from which such seal is fabricated is forced to bulge around the periphery of the opening, thereby securing the pipe in the opening and perfecting the seal therebetween.	5
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-171371, filed Jun. 12, 2002, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to a semiconductor device provided with a fuse for a redundancy circuit as seen in a embedded memory device, and in particular, to a semiconductor device which is improved in the fuse and pad portions thereof, and to a method for manufacturing such a semiconductor device. [0004] 2. Description of the Related Art [0005] When a fuse for utilizing a redundancy technique is formed on a surface of semiconductor substrate, the fuse is conventionally formed in a metal wiring layer which is disposed next to the second layer as counted downward from the metal pad. However, concomitant with the recent trend to further multiply the wiring layers, the metal wiring layer which is disposed below next to the uppermost metal wiring layer is prone to be made larger in thickness, resulting in an increase in thickness also of the interlayer insulating film which is disposed on the surface of the fuse. [0006] On the occasion of forming a fuse window, it is required not only to work this thickened interlayer insulating film but also to leave the interlayer insulating film on the surface of the fuse. In spite of the requirement that the film thickness of the interlayer insulating film to be left behind on the surface of the fuse be made as thin as possible in order to enable the fuse to be stably cut out by laser blow, the interlayer insulating film to be worked is made very large in thickness, as explained above, thereby making it very difficult to control the working of the interlayer insulating film. [0007] Further, in order to comply with the enhancement of the processing speed of semiconductor devices in recent years, the minimization of the delay of electric current in the metal wiring has become an major problem. It has been considered necessary to employ, as a countermeasure for solving the aforementioned problem, an insulating film which is low in dielectric constant (low-k film) as an interlayer insulating film to be interposed between the metal wirings. In this case, it is quite conceivable to fabricate a structure where this low-k film is disposed next to the second layer as counted downward from the metal pad. If so, the fuse in this low-k film will be cut out by laser blow, which however leads to the damage of this low-k film by the laser blow, thus badly affecting the characteristics and reliability of the semiconductor device. [0008] As explained above, in the case of a semiconductor device such as a embedded memory device, concomitant with the trend to multiply wiring layers, the metal wiring layer which is disposed below next to the uppermost metal wiring layer as well as the interlayer insulating film disposed on the surface of the fuse are prone to be made larger in thickness, and due to this increase in thickness of the interlayer insulating film, it has become very difficult to control the working of the interlayer insulating film on the occasion of forming a fuse window. Further, when a low-k film is employed as an interlayer insulating film in order to enhance the processing speed of semiconductor device, this low-k film will be damaged by the laser blow to be employed in the cutting of the fuse, thus badly affecting the characteristics and reliability of the semiconductor device. BRIEF SUMMARY OF THE INVENTION [0009] A semiconductor device according to one embodiment of the present invention comprises: a semiconductor substrate; a first metal wiring and a fuse, both being formed as the same level above the semiconductor substrate; a first insulating film deposited above the semiconductor substrate to cover the first metal wiring and the fuse, the first insulating film having a first pad opening arriving at the first metal wiring; a second metal wiring formed at least within the first pad opening, the second metal wiring not extending above the fuse; a stopper film formed on the first insulating film as well as on the second metal wiring; and a second insulating film formed above the stopper film; wherein a second pad opening is formed to expose a portion of the second metal wiring by removing the second insulating film and the stopper film, a fuse opening is formed above at least the fuse by removing the second insulating film and the stopper film, and by removing the first insulating film to intermediate in thickness. [0017] A method for manufacturing a semiconductor device according to one embodiment of the present invention comprises: forming a first metal wiring and a fuse above a semiconductor substrate; depositing a first insulating film above the semiconductor substrate to cover the first metal wiring and the fuse; selectively etching the first insulating film deposited on the first metal wiring to form a first pad opening; selectively forming a second metal wiring to contact with the first metal wiring through the first pad opening; forming a stopper film on the first insulating film and on the second metal wiring; forming a second insulating film above the stopper film; selectively etching parts of the second insulating film which correspond to a portion of the second metal wiring and to at least a portion of the fuse, thereby exposing a part of the stopper film; and etching away the part of the stopper film that has been exposed by the selective etching of the second insulating film. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING [0026] FIGS. 1A to 1 C respectively shows a cross-sectional view illustrating the element structure of a semiconductor device wherein a metal wiring layer which is disposed below next to the metal pad is employed as a fuse, and the problems accompanied with such a structure of a semiconductor device; [0027] FIG. 2 is a cross-sectional view illustrating the element structure of the semiconductor device according to a first embodiment of the present invention; [0028] FIGS. 3A to 3 G respectively shows a cross-sectional view illustrating the manufacturing steps of the semiconductor device according to a first embodiment of the present invention; [0029] FIG. 4 is a cross-sectional view illustrating the element structure of the semiconductor device representing a modified example of the first embodiment of the present invention; [0030] FIG. 5 is a cross-sectional view illustrating the element structure of the semiconductor device according to a second embodiment of the present invention; and [0031] FIG. 6 is a cross-sectional view illustrating the element structure of the semiconductor device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0032] According to the embodiments of the present invention, a metal wiring (a first metal wiring) which is disposed below next to a metal pad (a second metal wiring) is employed as a fuse, wherein a stopper film is formed on a first insulating film interposed between the first and second metal wirings, as well as on the second metal wiring. Further, after a second insulating film has been formed above the stopper film, etching is performed in two steps, i.e. the selective etching of the second insulating film and the selective etching of the stopper film. Owing to these procedures, it becomes possible not only to stably secure a residual insulating film over a fuse but also to reliably form a pad opening. [0033] More specifically, after a photoresist is patterned to provide it with patterns of pad portions and fuse window portions, the resultant photoresist pattern is employed as a mask to perform the etching of the second insulating film until the stopper film is exposed under the conditions which ensure a substantial etching selectivity ratio between the second insulating film and the stopper film. For example, in a case where a silicon oxide film is employed as the second insulating film and a silicon nitride film is employed as the stopper film, dry etching using a mixed gas comprising, for example, C 4 F 8 +CO+Ar is performed, thereby making it possible to easily perform the dry etching work of the second insulating film while ensuring a sufficient selectivity ratio relative to the stopper film. By optimizing the etching conditions, this selectivity ratio can be enhanced up to about 10, so that it is now possible to perform a sufficient over-etching and hence to achieve a stabilized working of the second insulating film. [0034] Further, when performing the etching of the stopper film subsequent to the working of the second insulating film, if the film thickness of the stopper film is preliminarily made sufficiently thin relative to the film thickness of the first insulating film, it is possible, concurrent with the etching of the first insulating film at the fuse opening, to perform a sufficient over-etching of the first insulating film relative to the etching of the stopper film. [0035] As a result, it is now possible not only to stably secure a residual insulating film on a fuse but also to reliably form a pad opening, thereby making it possible to enhance the characteristics and reliability of the device. [0036] As means for solving these conventional problems, it is conceivable to employ, as a fuse, a metal wiring layer disposed below next to the metal pad. Further, in order to simplify the manufacturing process, it is desired to perform the working of the pad portion and the formation of the fuse window by a single patterning process (en bloc opening work). However, when the over-etching is performed to a sufficient extent in the working of the pad opening by using the en bloc opening work according to the conventional technique, it becomes difficult to leave an interlayer insulating film at the fuse window portion, thus the fuse is exposed and hence possibly badly affecting the characteristics and reliability of the device. [0037] Following are explanations about the phenomena mentioned above, with reference to FIGS. 1A to 1 C. As shown in FIG. 1A , a first interlayer insulating film 103 is deposited on the surface of a semiconductor substrate 100 having a fuse 101 and a first metal wiring 102 formed in advance, and then, a first pad opening 105 is formed by exposure and dry etching. Thereafter, a metal wiring material is deposited on the exposed surface of the substrate 100 and by using exposure and dry etching, a second metal wiring (metal pad) 106 is formed. Then, after finishing the deposition of a second interlayer insulating film 109 , a photoresist 110 having a pattern including openings corresponding to a fuse window portion and also to a second pad opening portion is formed thereon. [0038] Then, as shown in FIG. 1B , by a dry etching, a fuse opening 112 and a second pad opening 111 are concurrently formed. On this occasion, in order to open the second pad opening 111 stably, an over-etching of about 50% is generally required, which however leads to the exposure of the fuse 101 due to this over-etching. The exposure of the fuse 101 will then lead to the corrosion of the fuse 101 , thus badly affecting the characteristics and reliability of the device. For example, if the thickness of the first interlayer insulating film 103 is assumed to be 500 nm and the thickness of the second interlayer insulating film 109 is assumed to be 1000 nm, when a 50% over-etching is performed at the second pad opening 111 , the fuse opening 112 penetrates completely. [0039] On the other hand, when it is tried to leave, without fail, a portion of the first interlayer insulating film 103 at the fuse opening 112 as shown in FIG. 1C , an etching residue 115 will be possibly left behind at the second pad opening 111 , thereby giving rise to the conductivity failure of the pad portion. [0040] As explained above, when it is tried to form the fuse by using the metal wiring which is disposed below next to the uppermost metal pad and to concurrently form the pad opening and the fuse opening by a single step of patterning in the manufacture of a semiconductor device such as a embedded memory device, it becomes very difficult to simultaneously realize the formation of the pad opening which is free from any residue of insulating film at the opening portion thereof and the formation of the fuse opening having a residual film of the insulating film left behind at the window portion thereof. [0041] Therefore, according to the embodiments of the present invention, a stopper-insulating film is provided to solve the aforementioned problems. The embodiments of the present invention will be explained as follows with reference with the drawings. [0000] (First Embodiment) [0042] FIG. 2 is a cross-sectional view illustrating the element structure of the semiconductor device according to a first embodiment of the present invention. [0043] Referring to FIG. 2, 10 represents a semiconductor substrate provided in advance with various kinds of elements such as a MOS transistor (not shown) and with a wiring structure. The semiconductor substrate is also provided in the surface region thereof with a fuse 11 and a first metal wiring 12 , both being buried in the surface region. On the substrate 10 is deposited a first interlayer insulating film 13 which is provided with a first pad opening 15 for enabling the first metal wiring 12 to be electrically contacted with a second metal wiring 16 which is formed in the first pad opening 15 . [0044] A stopper insulating film 18 is formed on the first interlayer insulating film 13 and on the second metal wiring 16 , and a second interlayer insulating film 19 is deposited on the stopper insulating film 18 . Further, a portion of the second interlayer insulating film 19 as well as a portion of the stopper insulating film 18 , both portions being located above the second metal wiring 16 , are etched away to form a second pad opening 21 . Additionally, a portion of the second interlayer insulating film 19 as well as a portion of the stopper insulating film 18 , both portions being located over the fuse 11 , are also etched away, and at the same time, the first interlayer insulating film 13 is also partially etched away, i.e. up to an intermediate portion in a thickness thereof, thereby forming a fuse opening 22 . [0045] Next, a method for manufacturing a semiconductor device according to this embodiment will be explained with reference to FIGS. 3A to 3 G. [0046] First of all, as shown in FIG. 3A , a first interlayer insulating film 13 is deposited on the semiconductor substrate 10 provided with a fuse 11 and a metal wiring 12 by using CVD, and then, a photoresist 14 having a predetermined pattern is formed on the first interlayer insulating film 13 by using lithography. Incidentally, the fuse 11 and the metal wiring 12 have been formed by so-called damascene process wherein a recessed portion having a depth of about 1 μm is formed in the interlayer insulating film deposited on the semiconductor substrate for instance, and then, Cu is buried in this recessed portion, the resultant surface being subsequently polished to flatten the surface, thereby forming the fuse 11 and the metal wiring 12 . Further, the interlayer insulating film 13 is formed from TEOS (tetraethoxy silane) silicon oxide having a thickness of about 500 nm. [0047] Then, as shown in FIG. 3B , by a dry etching using the photoresist 14 as a mask and also using a mixed gas such as C 4 F 8 +CO+Ar, the first interlayer insulating film 13 is selectively etched to form a first pad opening 15 . Subsequently, by using ashing and wet washing, the photoresist 14 is removed. [0048] Then, as shown in FIG. 3C , by sputtering, the second metal wiring 16 is deposited on the inside of the first pad opening 15 and on the first interlayer insulating film 13 . This metal wiring 16 is formed of Al having a thickness of 500 nm, for example. Then, by using lithography, the photoresist 17 having a pattern to cover the first pad opening 15 is formed on the metal wiring 16 . [0049] Then, as shown in FIG. 3D , by a dry etching using the photoresist 17 as a mask, the second metal wiring 16 is subjected to etching work. Thereafter, by using ashing and wet washing, the photoresist 17 is etched away. In this case, the second metal wiring 16 may be deposited only on the inside of the first pad opening 15 and on a region around the first pad opening 15 . Alternatively, the second metal wiring 16 may be deposited so as to extend over the first interlayer insulating film 13 . The portion of the second metal wiring 16 that has been extended over the first interlayer insulating film 13 may be utilized as a wiring. [0050] Then, as shown in FIG. 3E , by CVD, the stopper insulating film 18 made of a silicon nitride is deposited on the first interlayer insulating film 13 and on the second metal wiring 16 . Then, by CVD, the second interlayer insulating film 19 made of TEOS is deposited on the stopper insulating film 18 . In this case, the thickness of the stopper insulating film 18 is required to be sufficiently thin relative to the thickness of the first interlayer insulating film 13 . For example, the stopper insulating film 18 is formed to have a thickness of 100 nm. On the other hand, the second interlayer insulating film 19 is formed to have a thickness of 1 μm for instance. [0051] Then, as shown in FIG. 3F , a photoresist 20 is coated on the second interlayer insulating film 19 , and by using lithography, the formation of the second pad opening pattern and the formation of the fuse window pattern are concurrently formed by a single patterning step. [0052] Then, as shown in FIG. 3G , by using the photoresist 20 as a mask, the second interlayer insulating film 19 is subjected to etching until the stopper insulating film 18 is exposed under etching conditions ensuring a sufficient selective ratio relative to the stopper insulating film 18 . In this case, in order to enable the portion corresponding to the second pad pattern to be completely opened, the second interlayer insulating film 19 is over-etched by about 50%. As for the etching gas useful herein, a mixed gas containing C 4 F 8 +CO+Ar can be employed. [0053] Subsequently, by dry etching using a CHF 3 +O 2 mixed gas, the stopper insulating film 18 is etched with the photoresist 20 being employed as a mask. On this occasion, a portion of the first interlayer insulating film 13 which coincides with the fuse 11 and has been exposed due to the etching of the stopper insulating film 18 is half-etched. As a result, it is possible to simultaneously form the second pad opening 21 and the fuse opening 22 . Subsequently, by using ashing and wet washing, the photoresist 20 is removed to accomplish the structure shown in FIG. 2 . [0054] As explained above, according to this embodiment, due to the over-etching of the second interlayer insulating film 19 , it is now possible to reliably remove appropriate portions of this insulating film 19 located at the pad opening 21 and at the fuse opening 22 . In this case, since the underlying layer of the second interlayer insulating film 19 is constituted by the stopper insulating film 18 , there is little possibility that the first interlayer insulating film 13 is etched away at the fuse opening 22 . Furthermore, since the stopper insulating film 18 is formed sufficiently thinner than the first interlayer insulating film 13 , it is possible to reliably leave part of the first interlayer insulating film 13 at the fuse opening 22 even if the stopper insulating film 18 is over-etched. [0055] Accordingly, the formation of the second pad opening 21 can be performed without any possibility of leaving behind a residual insulating film therein, and at the same time, part of the insulating film can be reliably and stably left behind in the fuse opening 22 , thereby making it possible to enhance the characteristics and reliability of the device. [0056] Incidentally, the removal of the photoresist 20 in this embodiment can be performed prior to the etching of the stopper insulating film 18 . In this case, by using the photoresist 20 as a mask, the second interlayer insulating film 19 is subjected to etching work until the stopper insulating film 18 is exposed under etching conditions ensuring a sufficient selective ratio relative to the stopper insulating film 18 . Thereafter, by using ashing and wet washing, the photoresist 20 is removed. The resultant surface is then entirely subjected to an etch-back treatment by using dry etching to perform the working of the stopper insulating film 18 . [0057] Further, it is possible to apply this embodiment to a structure where a low-k film 42 is disposed below the interlayer insulating film 41 with the fuse 11 and the first metal wiring 12 being buried therein as shown in FIG. 4 . In this case, the interlayer insulating film 41 provided with the fuse 11 and the first metal wiring 12 may be formed of TEOS, and the low-k film 42 may be formed of a low dielectric constant film having a relative dielectric constant of less than 4, more preferably, 3 or less, such as polymethyl siloxane and polyarylene. [0058] When constructed in this manner, it is possible to obtain the effect that the low-k film 42 can be prevented from being damaged on the occasion of the laser blow to the fuse 11 . When the fuse is formed in a layer disposed next to the second layer 16 as counted downward from the metal pad, i.e. in the low-k film 42 as is the case of the conventional structure, damage will occur in this low-k film 42 on the occasion of the laser blow to the fuse 11 , thus deteriorating the characteristics and reliability of the semiconductor device. Whereas, according to this embodiment, since the fuse 11 is formed below next to the metal pad, the problem mentioned above can be reliably overcome. [0000] (Second Embodiment) [0059] FIG. 5 is a cross-sectional view illustrating the element structure of the semiconductor device according to a second embodiment of the present invention. Incidentally, the same portions as those of FIG. 2 are identified by the same reference symbols, thereby omitting the detailed explanation thereof. [0060] The main feature by which this embodiment can be distinguished from the aforementioned first embodiment resides in that the position of the second pad opening is off-set from the first pad opening. [0061] Although the fundamental manufacturing steps according to this embodiment are substantially the same as those of the first embodiment, this embodiment differs from the first embodiment in that the first pad opening 15 is not limited to only one place on the first metal wiring 12 but is formed at plural portions around the periphery of the first metal wiring 12 or formed ring-like along the periphery of the first metal wiring 12 . Further, the second metal wiring 16 is formed not only in the first pad opening 15 but also on the first interlayer insulating film 13 disposed on the first metal wiring 12 . Furthermore, the second pad opening 21 is formed not above the first pad opening 15 which is formed along the periphery of the first metal wiring 12 but above a central portion of the first metal wiring 12 , i.e. above a portion of the second metal wiring 16 deposited on the first interlayer insulating film 13 , the location of which coincides with a central portion of the first metal wiring 12 . [0062] When constructed in this manner, it is possible to obtain not only the same effect as that of the aforementioned first embodiment but also the additional effect as explained below. Namely, since the wire bonding is performed not through the portion where the second metal wiring 16 is directly formed on the first metal wiring 12 but through a portion of the second metal wiring 16 which is placed on the first interlayer insulating film 13 , any damage due to the wire bonding can be absorbed by the insulating film 13 , thereby making it possible to prevent the first metal wiring 12 from being damaged by the wire bonding. [0000] (Third Embodiment) [0063] FIG. 6 is a cross-sectional view illustrating the element structure of the semiconductor device according to a third embodiment of the present invention. Incidentally, the same portions as those of FIG. 2 are identified by the same reference symbols, thereby omitting the detailed explanation thereof. [0064] The main feature by which this embodiment can be distinguished from the aforementioned first embodiment resides in that the second metal wiring 16 is utilized also as a lead, and the position of the second pad opening 21 is off-set from the first pad opening 15 . [0065] Although the fundamental manufacturing steps according to this embodiment are substantially the same as those of the first embodiment, this embodiment differs from the first embodiment in that the second metal wiring 16 is formed not only in the first pad opening 15 and the peripheral region thereof but also on a region of the first interlayer insulating film 13 which is located away from the first pad opening 15 . Furthermore, the second pad opening 21 is formed not to expose the second metal wiring 16 at the first pad opening 15 but to expose the second metal wiring 16 formed on the first interlayer insulating film 13 . [0066] When constructed in this manner, it is possible to obtain almost the same effect as that of the aforementioned second embodiment. Moreover, since the second metal wiring 16 is employed also as a lead, the degree of freedom in positioning the second pad opening 21 will be increased. [0067] The present invention should not be construed as being limited to the aforementioned embodiments. For example, the material useful for the first metal wiring is not limited to the simple substance of Cu but may be formed of a material containing Cu as a main component. Further, a material mainly containing Ag may be substituted for Cu. Further, as for the material for the second metal wiring, the material useful herein is not limited to the simple substance of Al but may be formed of a material containing Al as a main component. Furthermore, the material for the second metal wiring is not be limited to Al. Namely, the material for the second metal wiring may be constituted by any kind of materials as far as they are more excellent in oxidation resistance and corrosion resistance as compared with the material constituting the first metal wiring. The wiring to be formed on the substrate may be constituted by an ordinary wiring which can be formed by RIE for instance. [0068] As for the stopper insulating film, it is desirable to employ a material which can be hardly etched in the etching process of the second interlayer insulating film. For example, when the second interlayer insulating film is formed of TEOS, the material for the stopper insulating film may be selected from silicon nitride and silicon carbide. In this manner, the present invention can be variously modified within the spirit thereof. [0069] As explained above in detail, according to the embodiments of the present invention, it becomes possible not only to stably secure a residual insulating film on a fuse but also to reliably form a pad opening in a structure where a metal wiring which is disposed below next to a metal pad is employed as a fuse, thereby making it possible to enhance the characteristics and reliability of the semiconductor device. [0070] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.	Disclosed is a semiconductor device comprising a semiconductor substrate, a first metal wiring and a fuse, both being formed as the same level above the semiconductor substrate, a first insulating film formed on the first metal wiring and the fuse, the first insulating film having a first pad opening arriving at the first metal wiring, a second metal wiring formed at least within the first pad opening, the second metal wiring not extending above the fuse, a stopper film formed on the first insulating film and the second metal wiring, and a second insulating film formed above the stopper film. A second pad opening is formed to expose the second metal wiring by removing the second insulating film and the stopper film, a fuse opening is formed above at least the fuse by removing the second insulating film and the stopper film, and by removing the first insulating film incompletely.	7
BACKGROUND OF THE INVENTION Natarajan et al. in Australian Patent Application No. 17,203 disclose acylalkylaminocarbonyl substituted amino and imino acid compounds of the formula ##STR2## wherein R 2 is certain aryl, aralkyl, hetero, or alkylene-hetero groups. These compounds possess angiotensin converting enzyme inhibition activity and enkephalinase inhibition activity depending upon the definition of X. Almquist et al. in U.S. Pat. No. 4,329,473 disclose angiotensin converting enzyme inhibiting compounds of the formula ##STR3## wherein R 2 is aryl, alkyl, alkoxy or benzyloxy. SUMMARY OF THE INVENTION This invention is directed to novel compounds of the formula ##STR4## Z is oxygen or sulfur. X is an amino or imino acid or ester of the formula ##STR5## n is zero, one or two. R 25 is lower alkyl of 1 to 4 carbons or ##STR6## R 7 is hydrogen, lower alkyl, halogen, hydroxy, ##STR7## R 10 is halogen or --Y--R 16 . R 11 , R' 11 , R 12 and R' 12 are independently selected from hydrogen and lower alkyl or R' 11 , R 12 and R' 12 are hydrogen and R 11 is ##STR8## R 13 is lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl, hydroxy, phenyl, phenoxy, phenylthio, or phenylmethyl. R 14 is lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl or hydroxy. m is zero, one, two, three, or four. p is one, two or three provided that p is more than one only if R 13 or R 14 is methyl, methoxy, chloro, or fluoro. R 15 is hydrogen or lower alkyl of 1 to 4 carbons. Y is oxygen or sulfur. R 16 is lower alkyl of 1 to 4 carbons, ##STR9## or the R 16 groups join to complete an unsubstitued 5- or 6-membered ring or said ring in which one or more of the carbons has a lower alkyl of 1 to 4 carbons or a di(lower alkyl of 1 or 4 carbons) substituent. ##STR10## r is an integer form 1 to 4 R 19 is lower alkyl, benzyl or phenethyl. R 20 is hydrogen, lower alkyl, benzyl or phenethyl. ##STR11## R 17 is hydrogen, lower alkyl, cycloalkyl, or phenyl. R 18 is hydrogen, lower alkyl, lower alkoxy or phenyl. R 21 and R 22 are independently selected from hydrogen and lower alkyl. R 23 is lower alkyl. R 24 is hydrogen, lower alkyl, ##STR12## DETAILED DESCRIPTION OF THE INVENTION This invention in its broadest aspects relates to the amino and imino acid and ester compounds of formula I and to compositions and the method of using such compounds as pharmaceutical agents. The term lower alkyl used in defining various symbols refers to straight or branched chain radicals having up to seven carbons. The preferred lower alkyl groups are up to four carbons with methyl and ethyl most preferred. Similarly the terms lower alkoxy and lower alkylthio refer to such lower alkyl groups attached to an oxygen or sulfur. The term cycloalkyl refers to saturated rings of 4 to 7 carbon atoms with cyclopentyl and cyclohexyl being most preferred. The term halogen refers to chloro, bromo and fluoro. The symbols ##STR13## represent that the alkylene bridge is attached to an available carbon atom. The compounds of formula I are obtained by treating an alcohol or mercaptan of the formula ##STR14## with phosgene in the presence of N-methylmorpholine and reacting the resulting compound with the amino or imino acid ester of the formula HX (III) particularly the hydrochloride salt thereof, wherein R 6 in the definition of X is an easily removably protecting group such as benzyl, benzhydryl, t-butyl, etc. Alternatively, the amino or imino acid ester of formula III could be first treated with phosgene and that product then reacted with the alcohol or mercaptan of formula II. Removal of the R 6 protecting group, for example, by hydrogenation when R 6 is benzyl, yields the acid products of formula I, i.e., R 6 is hydrogen. The alcohol intermediates of formula II, i.e., Z is oxygen, can be prepared by treating a chloroketone of the formula ##STR15## with tetrabutylammonium trifluoroacetate in an aqueous acetone solution. The mercaptan intermediates of formula II, i.e., Z is sulfur, can be prepared by treating the chloroketone of formula IV with sodium thioacetate and then treating the resulting S-acetyl product with ammonia or sodium hydroxide. The chloroketone of formula IV can be prepared as taught in Australian Patent Application 17,203 by treating a chloroketone of the formula ##STR16## wherein Prot is a protecting group such as benzyloxycarbonyl, with hydrogen bromide and acetic acid followed by reaction with acid halide of the formula ##STR17## wherein halo is Cl or Br in the presence of base such as sodium bicarbonate. In the above reactions if either R 3 or R 5 or both are ##STR18## then the hydroxyl, amino, imidazolyl, mercaptan or guanidinyl function should be protected during the reaction. Suitable protecting groups include benzyloxycarbonyl, t-butoxycarbonyl, benzyl, benzhydryl, trityl, etc., and nitro in the case of guanidinyl. The protecting group is removed by hydrogenation, treatment with acid, or other known methods following completion of the reaction. The ester products of formula I wherein R 6 is ##STR19## may be obtained by employing the amino or imino acid ester of formula III in the above reactions with such ester group already in place. The ester products of formula I wherein R 6 is ##STR20## can also be obtained by treating the product of formula I wherein R 6 is hydrogen with a molar excess of the compound of the formula ##STR21## wherein L is a leaving group such as chlorine, bromine, tolylsulfonyl, etc. The ester products of formula I wherein R 6 ##STR22## can be prepared by treating the product of formula I wherein R 6 is hydrogen with a molar excess of the compound of the formula ##STR23## The ester products of formula I wherein R 6 is ##STR24## can be prepared by coupling the product of formula I wherein R 6 is hydrogen with a molar excess of the compound of the formula ##STR25## or the formula ##STR26## in the presence of a coupling agent such as dicyclohexylcarbodiimide and the optional presence of a catalyst such as dimethylaminopyridine followed by removal of the hydroxyl protecting group. Similarly, the ester products of formula I wherein R 6 is ##STR27## can be prepared by coupling the product of formula I wherein R 6 is hydrogen with a molar excess of the compound of formula HO--CH.sub.2 --CH.sub.2 --N--(CH.sub.3).sub.2 (XI) or the formula ##STR28## in the presence of a coupling agent such as dicyclohexylcarbodiimide and the optional presence of a catalyst such as dimethylaminopyridine. The products of formula I wherein R 7 is amino may be obtained by reducing the corresponding products of formula I wherein R 7 is azido. Preferred compounds of this invention are those of formula I wherein: X is: ##STR29## R 6 is hydrogen straight or branched chain lower alkyl of 1 to 4 carbons, or an alkali metal salt ion. R 4 is cyclohexyl or phenyl and R 5 is hydrogen. R 4 is hydrogen and R 5 is methyl, ##STR30## R 7 is hydrogen, cyclohexyl, lower alkoxy of 1 to 4 carbons, ##STR31## R 13 is methyl, methoxy, methylthio, Cl, Br, F, or hydroxy. m is zero, one or two. t is two or three. R 2 is ##STR32## R 3 is straight or branched chain lower alkyl of 1 to 4 carbons, ##STR33## R 14 is methyl, methoxy, methylthio, Cl, Br, F, or hydroxy. Most preferred compounds of this invention are those of formula I wherein: X is ##STR34## Z is oxygen. R 6 is hydrogen or an alkali metal salt ion. R 2 is phenyl. R 3 is phenylmethyl. The compounds of formula I wherein R 6 is hydrogen form salts with a variety of inorganic or organic bases. The nontoxic, pharmaceutically acceptable salts are preferred, although other salts are also useful in isolating or purifying the product. Such pharmaceutically acceptable salts include alkali metal salts such as sodium, potassium or lithium, alkaline earth metal salts such as calcium or magnesium, and salts derived from amino acids such as arginine, lysine, etc. The salts are obtained by reacting the acid form of the compound with an equivalent of the base supplying the desired ion in a medium in which the salt precipitates or in aqueous medium and then lyophilizing. The compounds of formula I when R 3 is other than hydrogen contain an asymmetric center as represented by the * in formula I. Thus, the compounds of formula I can exist in diastereomeric forms or in mixtures thereof. The above described processes can utilize racemates, enantiomers or diastereomers as starting materials. When diastereomeric products are prepared, they can be separated by conventional chromatographic or fractional crystallization methods. The products of formula I wherein the imino acid ring is monosubstituted give rise to cis-trans isomerism. The configuration of the final product will depend upon the configuration of the R 7 , R 8 and R 9 substituent in the starting material of formula III. The compounds of formula I, and the pharmaceutically acceptable salts thereof, are hypotensive agents. They inhibit the conversion of the decapeptide angiotensin I to angiotensin II and, therefore, are useful in reducing or relieving angiotensin related hypertension. The action of the enzyme renin on angiotensinogen, a pseudoglobulin in blood plasma, produces angiotensin I. Angiotensin I is converted by angiotensin converting enzyme (ACE) to angiotensin II. The latter is an active pressor substance which has been implicated as the causative agent in several forms of hypertension in various mammalian species, e.g., humans. The compounds of this invention intervene in the angiotensinogen→(renin)→angiotensin I→angiotensin II sequence by inhibiting angiotensin converting enzyme and reducing or eliminating the formation of the pressor substance angiotensin II. Thus by the administration of a composition containing one (or a combination) of the compounds of this invention, angiotensin dependent hypertension in a species of mammal (e.g., humans) suffering therefrom is alleviated. A single dose, or preferably two to four divided daily doses, provided on a basis of about 0.1 to 100 mg., preferably about 1 to 50 mg., per kg. of body weight per day is appropriate to reduce blood pressure. The substance is preferably administered orally but parenteral routes such as the subcutaneous, intramuscular, intravenous or intraperitoneal routes can also be employed. The compounds of this invention can also be formulated in combination with a diuretic for the treatment of hypertension. A combination product comprising a compound of this invention and a diuretic can be administered in an effective amount which comprises a total daily dosage of about 30 to 600 mg., preferably about 30 to 330 mg. of a compound of this invention, and about 15 to 300 mg., preferably about 15 to 200 mg. of the diuretic, to a mammalian species in need thereof. Exemplary of the diuretics contemplated for use in combination of this invention are the thiazide diuretics, e.g., chlorothiazide, hydrochlorothiazide, flumethiazide, hydroflumethiazide, bendroflumethiazide, methyclothiazide, trichloromethiazide, polythiazide or benzthiazide as well as ethacrynic acid, ticrynafen, chlorthalidone, furosemide, musolimine, bumetanide, triamterene, amiloride and spironolactone and salts of such compounds. The compounds of formula I can be formulated for use in the reduction of blood pressure in compositions such as tablets, capsules or elixirs for oral administration, or in sterile solutions or suspensions for parenteral administration. About 10 to 500 mg. of a compound of formula I is compounded with physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavor, etc., in a unit dosage form as called for by accepted pharmaceutical practice. The amount of active substance in these compositions or preparations is such that a suitable dosage in the range indicated is obtained. The compounds of formula I wherein X is ##STR35## also possess enkephalinase inhibition activity and are useful as analgesic agents. Thus, by the administration of a composition containing one or a combination of such compounds of formula I or a pharmaceutically acceptable salt thereof, pain is alleviated in the mammalian host. A single dose, or preferably two to four divided daily doses, provided on a basis of about 0.1 to about 100mg. per kilogram of body weight per day, preferably about 1 to about 50 mg. per kilogram per day, produces the desired analgesic activity. The composition is preferably administered orally but parenteral routes such as subcutaneous can also be employed. The following examples are illustrative of the invention. Temperatures are given in degrees centigrade. EXAMPLE 1 1-[[[(S)-3-(Benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline (a) (S)-3-Amino-1-chloro-4-phenyl-2-butanone, hydrogen bromide (S)-[3-Chloro-2-oxo-1-(phenylmethyl)propyl]carbamic acid, phenylmethyl ester (51.4 g.) is dissolved in a mixture of acetic acid (252 ml.) and hydrogen bromide in acetic acid (3.45N, 348 ml.) and kept at room temperaure for 1.5 hours. The reaction mixture is then concentrated in vacuo and precipitated with ether to obtain 36.6 g. of (S)-3-amino-1-chloro-4-phenyl-2-butanone, hydrogen bromide; m.p. (175°) 177°-179°. (b) (S)-N-[3-Chloro-2-oxo-1-(phenylmethyl)propyl]benzamide (S)-3-Amino-1-chloro-4-phenyl-2-butanone, hydrogen bromide (36.3 g., 130.3 mmole) is suspended in 520 ml. of dry tetrahydrofuran and 18.2 ml. of triethylamine (130.3 mmole) with stirring for ten minutes. The mixture is placed in an ice bath and 15.2 ml. of benzoyl chloride is added followed by 10.95 g. of sodium bicarbonate. After 5 minutes the ice bath is removed and the reaction mixture is kept at room temperature for 1.5 hours. The reaction mixture is then concentrated in vacuo and the residue taken up in 1 l. of aqueous methanol (10% water). The precipitate is collected, filtered and washed with methanol to obtain 25.3 g. of (S)-N-[3-chloro-2- oxo-1 -(phenylmethyl)propyl]benzamide; m.p. (160°) 170°-172° (dec.); [α] D 23 =-129° (c=1.7, dimethylformamide). (c) (S)-N-[3-Hydroxy-2-oxo-1-(phenylmethyl)propyl]benzamide Tetrabutylammonium hydroxide (40% by weight, 25 ml) solution in water is triturated with trifluoroacetic acid to a clear end point (phenolphthalein). The solution is concentrated under reduced pressure and the oily residue is chased with toluene (4 times). The residue solidifies upon drying in high vacuum to give 12.0 g. of white solid tetrabutylammonium trifluoroacetate. A reaction mixture of (S)-N-[3-chloro-2-oxo-1-(phenylmethyl)propyl]benzamide (3.6 g., 11.9 mmole) and tetrabutylammonium trifluoroacetate (8.6 g., 24.0 mmole) in acetone (200 ml., containing 1% water) is refluxed overnight. The reaction mixture is concentrated under reduced pressure and the oily residue is purified by flash chromatography (LPS-1 silica gel; ethyl acetate:hexane, 2:3) to give 1.93 g. of white solid (S)-N-[3-hydroxy-2-oxo-1-(phenylmethyl)propyl] benzamide; m.p. 130°-131°. TLC (silica gel; ethyl acetate:hexane, 2:3) R f =0.28. Anal. calc'd. for C 17 H 17 NO 3 : C, 72.06; H, 6.05; N, 4.94 Found: C, 71.72; H, 6.17; N, 4.79. (d) 1-[[[(S)-3-(Benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline, phenylmethyl ester A 12.5% solution of phosgene in benzene (6.4 ml., 6.0 mmole) is added with stirring to a solution of (S)-N-[3-hydroxy-2-oxo-1-(phenylmethyl)propyl]benzamide (1.38 g., 4.87 mmole) in methylene chloride (30 ml., distilled) and N-methylmorpholine (0.80 ml., 7.3 mmole) at -20°. After stirring at -20 ° under nitrogen for 30 minutes and at room temperature for 45 minutes, the reaction mixture is concentrated under reduced pressure and the residue is chased once with methylene chloride (10 ml.). The residue is suspended in methylene chloride (30 ml.) and treated with a solution of L-proline, phenylmethyl ester, hydrochloride (1.78 g., 7.3 mmole) and N-methylmorpholine (1.33 ml., 12.17 mmole) in methylene chloride (30 ml.). After stirring at room temperature overnight, the reaction mixture is concentrated under reduced pressure, the residue is redissolved in ethyl acetate (100 ml.) and washed with water (twice), saturated sodium bicarbonate (twice), 10% potassium bisulfate (twice), dried (Na 2 SO 4 ), and concentrated into 2.1 g. of an oily residue. Flash chromatography (LPS-1 silica gel, 30% ethyl acetate/hexane) gives 1.39 g. of 1-[[[(S)-3-(benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline, phenylmethyl ester as a colorless foam. TLC (silica gel, 50% ethyl acetate/hexane) R f =0.3. (e) 1-[[[(S)-3-(Benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline A solution of the phenylmethyl ester product from part (d) (0.7 g., 1.43 mmole) in ethyl acetate (30 ml.) containing 10% palladium on carbon catalyst (150 mg.) is hydrogenated for 27 hours. The mixture is filtered, the filtrate is quickly extracted with cold 1N sodium hydroxide (2×20 ml.), the aqueous portion is acidified with 10% potassium bisulfate and extracted with ethyl acetate (3 times). The combined ethyl acetate extracts are dried (Na 2 SO 4 ) and concentrated under reduced pressure to yield 0.51 g. of 1-[[[(S)-3-(benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline as a white foam; m.p. 55°-65° (glass). [α] D 25 =-33.8°; (c=0.5, methanol). TLC (silica gel; chloroform:methanol:acetic acid, 18:1:1) R f =0.46. Anal. calc'd. for C 22 H 24 N 2 O 6 .1H 2 O: C, 62.43; H, 5.92; N, 6.33 Found: C, 62.49; H, 5.84; N, 5.89. EXAMPLES 2-27 Following the procedure of Example 1, the alcohol or mercaptan shown in Col. I is treated with phosgene and the resulting product is reacted with the amino or imino acid ester shown in Col. II to give the ester product shown in Col. III. Removal of the R 6 ester group yields the corresponding products in acid form, i.e., R 6 is hydrogen. __________________________________________________________________________Col. I Col. II Col III ##STR36## HX ##STR37##Example R.sub.3 R.sub.2 Z X__________________________________________________________________________ 2 ##STR38## ##STR39## S ##STR40## 3 ##STR41## ##STR42## O ##STR43## 4 ##STR44## ##STR45## O ##STR46## 5 ##STR47## ##STR48## S ##STR49## 6 ##STR50## ##STR51## O ##STR52## 7 ##STR53## ##STR54## O ##STR55## 8 ##STR56## ##STR57## S ##STR58## 9 ##STR59## ##STR60## O ##STR61##10 ##STR62## ##STR63## O ##STR64##11 ##STR65## ##STR66## S ##STR67##12 H.sub.5 C.sub.2H.sub.2 C ##STR68## O ##STR69##13 ##STR70## ##STR71## S ##STR72##14 ##STR73## ##STR74## O ##STR75##15 ##STR76## ##STR77## S ##STR78##16 ##STR79## ##STR80## O ##STR81##17 ##STR82## ##STR83## O ##STR84##18 ##STR85## ##STR86## S ##STR87##19 ##STR88## ##STR89## O ##STR90##20 ##STR91## ##STR92## S ##STR93##21 ##STR94## ##STR95## O ##STR96##22 ##STR97## ##STR98## S ##STR99##23 ##STR100## ##STR101## O ##STR102##24 ##STR103## ##STR104## O ##STR105##25 ##STR106## ##STR107## O ##STR108##26 ##STR109## ##STR110## O ##STR111##27 ##STR112## ##STR113## O ##STR114##__________________________________________________________________________ The R.sub.3 protecting groups shown in Examples 14 to 17 and the R.sub.5 protecting group shown in Example 24 are removed as the last step in the synthesis. The R.sub.6 ester groups shown in Examples 25 to 27 are not removed. EXAMPLE 28 1000 tablets each containing the following ingredients: ______________________________________1-[[[(S)--3-(Benzoylamino)-2-oxo- 100 mg.4-phenylbutyl]oxy]carbonyl]-L-prolineCornstarch 50 mg.Gelatin 7.5 mg.Avicel(microcrystalline cellulose) 25 mg.Magnesium stearate 2.5 mg. 185 mg.______________________________________ are prepared from sufficient bulk quantities by mixing 1-[[[(S)-3-(benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline and cornstarch with an aqueous solution of the gelatin. The mixture is dried and ground to a fine powder. The Avicel and then the magnesium stearate are admixed with granulation. This mixture is then compressed in a tablet press to form 1000 tablets each containing 100 mg. of active ingredient. In a similar manner, tablets containing 100 mg. of the product of any of Examples 2 to 27 can be prepared. A similar procedure can be employed to form tablets containing 50 mg. of active ingredient. EXAMPLE 29 Two piece #1 gelatin capsules are filled with a mixture of the following ingredients: ______________________________________1-[[[(S)--3-(Benzoylamino)-2-oxo- 50 mg.4-phenylbutyl]oxy]carbonyl]-L-prolineMagnesium stearate 7 mg.Lactose 193 mg. 250 mg.______________________________________ In a similar manner capsules containing 50 mg. of the product of any of Examples 2 to 27 can be prepared. EXAMPLE 30 An injectable solution is prepared as follows: ______________________________________1-[[[(S)--3-(Benzoylamino)-2-oxo- 500 g.4-phenylbutyl]oxy]carbonyl]-L-prolineMethyl paraben 5 g.Propyl paraben 1 g.Sodium chloride 25 g.Water for injection 5 l______________________________________ The active substance, preservatives, and sodium chloride are dissolved in 3 liters of water for injection and then the volume is brought up to 5 liters. The solution is filtered through a sterile filter and aseptically filled into presterilized vials which are closed with presterilized rubber closures. Each vial contains 5 ml. of solution in a concentration of 100 mg. of active ingredient per ml. of solution for injection. In a similar manner, an injectable solution containing 100 mg. of active ingredient per ml. of solution can be prepared for the product of any of Examples 2 to 27. EXAMPLE 31 1000 tablets each containing the following ingredients: ______________________________________1-[[[(S)--3-(Benzoylamino)-2-oxo- 100 mg.4-phenylbutyl]oxy]carbonyl]-L-prolineAvicel 100 mg.Hydrochlorothiazide 12.5 mg.Lactose 113 mg.Cornstarch 17.5 mg.Stearic acid 7 mg.______________________________________ are prepared from sufficient bulk quatities by slugging the 1-[[[(S)-3-(benzoylamino)-2-oxo-4-phenylbutyl]oxy]carbonyl]-L-proline, Avicel, and a portion of the stearic acid. The slugs are ground and passed through a #2 screen, then mixed with the hydrochlorothiazide, lactose, cornstarch, and remainder of the stearic acid. The mixture is compressed into 350 mg. capsule shaped tablets in a tablet press. The tablets are scored for dividing in half. In similar manner, tablets can be prepared containing 100 mg. of the product of any of Examples 2 to 27.	Compounds of the formula ##STR1## wherein Z is oxygen or sulfur are disclosed. These compounds are useful as hypotensive agents due to their angiotensin converting enzyme inhibition activity and depending upon the definition of X may also be useful as analgesics due to their enkephalinase inhibition activity.	2
CROSS-REFERENCE [0001] This application is a divisional application of Ser. No. 11/485,168, filed Jul. 11, 2006, which is incorporated herein by reference in its entirety, and to which application we claim priority under 35 USC § 121. This application also claims the benefit of U.S. Provisional Application No. 60/700,105, filed Jul. 19, 2005, which application is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention is directed to improvements in smoking devices, particularly to smoking articles which employ a formed tobacco cartridge as a source of producing vapor by heat transfer to the cartridge by conduction, convection, and radiation for smoke and flavor. The present invention relates to self-contained vaporization devices, and more particularly, to a low-temperature vaporization device for use of tobacco product. The device is of an elongated main body with a mouthpiece at one end and an attached tubular casing at the other end having a vaporization chamber and a heater. The mouthpiece and the casing form an unitary unit. [0004] 2. Description of the Related Art [0005] Smoking devices, such as cigarette holders and pipes are well known in the art for providing flavored vapor from a smokeable substance to a user for therapeutic and smoking pleasure. However, existing devices used have no control of heating and combustion of the tobacco products. The devices tend to produce toxic, tarry and carcinogenic by-products which are harmful and also impart a bitter and burnt taste to a mouth of a user. [0006] A further problem is that there is no control of contamination of the inhaled vapor mixture with heater exhaust gases, due to inappropriate proportioning and location of the inlets and the exhaust vents. Typically, the exhaust gas is used to directly heat the tobacco, and those gases contain harmful byproducts of incomplete combustion. [0007] In an effort to overcome these deficiencies, there have been numerous attempts to provide a device structure and the substance for producing vapor for smoking which is free from harmful by-product and would provide a cool and soothing vapor for smoking. [0008] For example, U.S. Patent Application No. 2004/0237974 A1, published on Dec. 2, 2004 for Min discloses a filtering cigarette and cigar holder which removes tar and nicotine from the tobacco smoke. [0009] U.S. Patent Application No. 2004/0031495 A1, published on Feb. 19, 2004 for Steinberg discloses a vaporization pipe with flame filter which uses a flame to vaporize the smoking substance. [0010] U.S. Pat. No. 6,164,287, issued Dec. 26, 2000 to White, describes a smoking device which produces smoke from tobacco at low temperatures, without producing harmful byproducts. [0011] U.S. Pat. No. 4,848,374, issued Jul. 18, 1989 to Chard et al describe a smoking device to vaporize aerosol precursor, an event which precedes condensation to mainstream aerosol precursor by contact with heated surface rather than by hot gases into the mouth of a smoker. [0012] U.S. Pat. No. 4,219,032, issued Aug. 26, 1980 to Tabatznik et al describe a smoking device wherein an extracted smoke is cooled by passing it through a suitable liquid to provide a soothing smoke. [0013] U.S. Pat. No. 4,020,853, issued May 3, 1977 to Nuttall, describes a smoking pipe made of ceramic material such as colored and ornamental porcelain for enhancing the artistic look, and also to provide a circulating air to keep the outer wall of the pipe cool and safe for handling. [0014] U.S. Pat. No. 3,792,704, issued Feb. 19, 1974 to Parker, describes a pipe tobacco smoking system, wherein the pipe and the tobacco capsule are mutually designed to yield a slim-line smoking combination that can be manufactured from relatively low temperature thermoplastic material. SUMMARY OF THE INVENTION [0015] The present invention is drawn to a novel smoking device consisting of a mouthpiece and a casing having a heater, a low temperature vaporization chamber, a fuel tank, an igniter with control means for maintaining equilibrium point by keeping the operating temperature below 400 F, preferably below 350 F during combustion whereby in order to maintain a stable operating temperature, a thermal regulator is used to control flow rate of the fuel. [0016] Accordingly, it is principal object of the invention to provide a mouthpiece made of a high temperature food-safe material, such as ceramic, glass, or high temperature plastics known as PEI resin (brand name Ultem). However, suitable plastic or wood, etc., could also be used but would additionally require an insulating material that would prevent excessive heat reaching the user's lips. [0017] Additionally, air inlets are directed downwards, so that fresh ambient air drawn through mixes with the vapor generated into the vaporization chamber located above the smokeable substance cartridge, which is extracted from the cartridge by inlets located below the cartridge and drawn into user's mouth for inhalation. [0018] It is another object of the invention to provide air inlet or inlets having a diameter and direction sized to admit ambient air into the chamber to heat up the substance and not effect the operating temperature and also regulating the velocity of ambient air entering and mixing with the vapor generated from combustion, radiation and convection in the chamber at such a rate that the proportionate inhalation passage provides a perception to the user as if the smoke is drawn through a cigarette. [0019] It is still another object of the invention to provide a heater which is separated from the vapor chamber by an insulating medium such as ring made of PTFE, ceramic or other insulating material and thereby preventing the exhaust gases produced by the heater from entering and contaminating the vapor in the vaporization chamber collected for inhalation. [0020] Another object of the invention to provide a heater is formed of a conductive shell and a catalyst, the shell may be of one or more material formed by welding or pressing together. Whereas, the catalyst could be of platinum or palladium impregnated metal or glass or other suitable material, which provides for efficient flameless combustion of the fuel and glows red when heated to indicate that the device is activated. Additionally, a feedback loop could be employed to regulate the desired temperature. [0021] Preferably the tobacco cartridge formed and shaped for easier insertion into the heating chamber and to snugly fit into the cavity of the heating chamber for improved thermal conduction and vaporization. The cartridges are formed and wrapped into wrapper which does not produce significant amount of harmful gases. [0022] These and other objects of the present invention will become readily apparent upon further review of the following specifications and drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0023] FIG. 1 is a side view of a portable vaporization device, according to a preferred embodiment of the present invention. [0024] FIG. 2 is a sectional view of the same embodiment. [0025] FIG. 3 is a perspective view of a heater, according to the same embodiment. [0026] FIG. 4 is a cutaway view of an alternate embodiment according to the present invention. [0027] FIG. 5 is a sectional detail view of a tobacco cartridge, according to the preferred embodiment. [0028] FIG. 6 is a perspective view of a tobacco cartridge, according to the preferred embodiment. [0029] FIG. 7 is a sectional detail view of a tobacco cartridge, according to an alternate embodiment. [0030] FIG. 8 is a sectional detail view of a tobacco cartridge, according to an alternate embodiment. DETAILED DESCRIPTION OF THE INVENTION [0031] Referring to FIG. 1 and FIG. 2 , the exterior of the device 10 comprises a mouthpiece 11 , a tubular case 12 , and the base 14 of a butane tank 21 . The mouthpiece is removable and creates an airtight seal with the interior of the case. With the mouthpiece removed, a tobacco cartridge ( FIG. 5 ) is introduced to vaporization chamber 15 of a heater 16 . The mouthpiece is then reinserted to close the device. [0032] The mouthpiece is made of a high-temperature and food-safe material such as ceramic, glass, or various high-temperature plastics such as PEI resin (brand name Ultem). Design is simplified by use of high temperature materials, but standard plastics or wood, etc, could also be used with the addition of an insulating component that prevents any excessive heat from reaching the user's lips. [0033] To activate the device, the butane tank is pulled axially outward, partially removing it from the case. This starts the flow of butane by opening a master valve 18 , and then activating a piezoelectric igniter 13 . The tank remains in the partially removed position for the duration of use. While the master valve is open, butane flows through a thermal regulator 17 , and into the carburetor 20 . Ambient air enters the case through slot 19 . A venturi in the carburetor entrains air, causing it to mix with the butane. The mixture then flows into the heater 16 . [0034] The lead of the ignitor is positioned in the heater. With the spark of the ignitor (immediately following the start of gas flow) the gas ignites and heat starts conducting throughout the heater. Heat transfers to the cartridge by conduction, convection, and radiation. The cartridge is shaped to fill the chamber, so as to maximize surface contact for thermal conduction. [0035] As the cartridge heats, vapor generates within the cartridge and in the space immediately above it. When a user draws on the device, fresh air enters through air inlet 22 , mixes with the vapor, and the mixture is delivered to the user via the inhalation passage 23 . In the preferred embodiment, the air inlet or inlets are directed downward, so as to improve the extraction of vapor from the cartridge. They could also be directed along a diagonal through the mouthpiece, or laterally through the case itself, above the cartridge. [0036] FIG. 3 depicts a detailed view of the heater 16 . The heater comprises a thermally conductive shell 26 and catalyst 27 . The shell could be comprised of one material, or a combination of materials welded or pressed together. The catalyst could be platinum- or palladium-impregnated metal or glass, or other suitable material known to those skilled in the art. The catalyst provides for efficient flame-less combustion of the butane. The vent 28 of the heater is positioned such that it is visible through the slot 29 of the body as shown in FIG. 1 . This allows the user to see the catalyst which, when heated, can glow red to indicate that the device has been activated. [0037] Referring again to FIG. 3 , adjacent to the heater and in intimate thermal contact is the thermal regulator 17 . As the temperature of the heater increases, so does that of the regulator. The regulator is designed to restrict the flow of butane as the temperature increases, thus creating a feedback loop. In the preferred embodiment, the regulator consists of a bimetallic strip 60 and silicone tubing 61 which is the conduit of the butane. The two are arranged such that as the bimetallic strip heats up, it curls to pinch the silicone tube and thereby restrict the flow of butane. The reduced flow of butane results in less heat generated. The heater subsequently cools down, and so does the regulator, allowing more butane to flow again. The overall result is that a stable operating temperature is established in the heater. Such a system can be readily tuned to achieve an operating temperature that varies by less than +/−5 degrees Fahrenheit. [0038] The regulator further comprises a moveable backplate 62 which allows adjustability of the operating temperature by adjusting the temperature at which the bi-metallic actuator closes the tube valve. This is to be performed once at manufacture, to calibrate the device. In alternate embodiments, a control means could be used to allow the target temperature of the device changed during operation. [0039] In the preferred embodiment, the regulator comprises in part a bi-metallic strip and silicone tubing valve. In alternate embodiments, the regulator could be comprised of other materials and configurations, as described later. [0040] For the purposes of vaporizing most botanicals in this device, the desired operating temperature is below 400 F; preferably below 350 F. [0041] In the preferred embodiment, the air inlet diameter is sized such that inhalation is somewhat inhibited. This allows time for ambient air entering the chamber to heat up and not affect operating temperature considerably. It also increases velocity of the entering air, which improves circulation and mixing in the vaporization chamber. It also creates a partial vacuum, lowering the vapor point temperature for material contained in the vaporization chamber. The reduction in draw rate can also serve to give the impression of drawing on a cigarette or pipe. Both the fresh air inlet and inhalation passage can be adjusted to provide appropriate draw rate for the operating temperature of the device, and the perception intended for the user. [0042] Once the cartridge is consumed, the device is turned off by pushing the tank back into the case, closing the master valve. The spent tobacco cartridge is removed by opening the device and turning the body over. In the preferred embodiment, the cartridge simply falls out. In alternate embodiments, a mechanism could be used to quickly and easily remove the cartridge. This mechanism could include, but does not require, the use of a pin or slide part to eject the cartridge as another part of the device is moved or removed. The removal mechanism could also involve introduction of a foreign object. [0043] In an alternate embodiment, the mouthpiece is permanently attached to the body. In that case, the vaporization chamber could be accessed by operating a sliding or hinged door, or similar means, built into the device. [0044] The heater of the device is fitted into the case with an insulator 24 . The insulator could be made of PEI (brand name Ultem), ceramic, or other insulating material. The insulator serves to minimize thermal transfer from the heater to the case, while creating an air-tight seal. The seal prevents exhaust gases produced by the heater from entering the vaporization chamber. Exhaust gases are instead vented out the case slots. Since the air inlet is distant from the slots, there is substantially no contamination of the inhaled vapor mixture by heater exhaust gases. [0045] In an alternate embodiment, the insulator could be a partially hollow shell, containing a sealed vacuum. In another embodiment, the heater might be sealed directly to the case by braising in a vacuum furnace, so as to create a vacuum between the two and obviate need for an insulator component. [0046] In the preferred embodiment, the tank is made of a translucent material. This allows the user to determine the level of fuel remaining by looking at the base of the tank. [0047] In the preferred embodiment, the case is made of a material that is either a good thermal conductor (such as aluminum), or a poor one (such as ceramics). In both cases, the effect is that the body remains cool enough to touch over a large portion of its surface. [0048] In the preferred embodiment, a bimetallic actuator is used in the regulator. In alternate embodiments, a shape memory alloy actuator such nickel-titanium alloys (“Nitinol”) could be used. Alternatively, a paraffin-filled component that expands and contracts to modulate butane flow could be employed. Alternatively, a system could be employed to measure the current temperature, e.g., with a thermocouple sensor and compare it to a prescribed temperature, e.g., with a micro-controller, and by controlling an electromechanical valve, e.g., servo or solenoid valve. In an embodiment with user-selected temperature, as described above, the selected temperature could be used as an input to this system. [0049] In the preferred embodiment, a thermal regulator is used. In an alternate embodiment, the device is constructed without an active regulating element. This could result in reduced complexity and in lowering the overall cost of the device. In this case, the flow of butane is set at a low level. In use, the temperature inside the chamber increases until an equilibrium point where additional heat introduced equals the heat lost to the environment. Heat is lost by conduction through the body of the device, and with the vapor delivered to the user. This equilibrium point determines the operating temperature of the device. By changing the butane flow rate, size and material of the burner, and other factors, the system can be calibrated to provide a fairly stable desired operating temperature. [0050] The principal advantage of the preferred bimetallic regulator feedback loop methods over the equilibrium method is that the operating temperature is not dependent on environmental factors such as ambient temperature and wind. [0051] In the preferred embodiment, a piezo-electric ignitor is used. Other igniters could be used, such as, a flint starter or battery-powered resistive coil. [0052] In the preferred embodiment, the butane tank is meant to be refillable, and has a port 25 for that purpose. As an alternate embodiment, the tank might be disposable once its fuel is exhausted. A release mechanism such as a pin or cam would be employed allowing the user to quickly remove the depleted tank and replace it with a full one. The replaceable tank might include additional parts of the device including, but not limited to, the ignitor and heater. Butane is the preferred fuel source, but could be replaced by other liquid fuels, such as ethanol. [0053] In alternate embodiments of the present invention, various means of feedback could be used to indicate the following states or metrics of the device: 1) the device is on, 2) the current temperature of the vaporization chamber, 3) the chamber is below a prescribed operating temperature, 4) the chamber has reached a prescribed operating temperature and vapor is ready for consumption, and 5) the chamber has exceeded a prescribed operating temperature. [0054] The means of the feedback includes both physical and electronic implementations. Possibilities include thermochromatic paint, light-emitting diodes and liquid crystal display. The sensing and control means for electronic feedback could be implemented by use of thermocouple and micro-controller, as is known to those skilled in the art. [0055] Active elements contained in botanicals vaporize at different temperatures. In the preferred embodiment, the device is calibrated to establish a single stable temperature, intended for vaporizing solely tobacco or solely chamomile, for example. In alternate embodiments, a control means would be used to select a variety of temperature settings. The user would choose which setting based on the type of cartridge used. The control means could effect a desired temperature mechanically, such as by changing flow rate of the valve, or electronically, such as by electromechanical valve and micro-controller intermediary. [0056] Butane was found to be the most energy-dense and practical fuel source. In alternate embodiments of the invention, the butane heating system is replaced by a battery-powered electric heater or other compact heat source. [0057] FIG. 4 depicts a cutaway view of an alternate embodiment which more closely resembles a traditional pipe form. In this embodiment the device retains all of the critical elements from the preferred embodiment. The user inserts a tobacco cartridge 40 , under a sliding top piece 41 , where the cartridge mates with the heater 42 . Fuel held in the tank 43 is released by turning dial 44 to open master valve 45 . The fuel travels through the regulator 51 , and then through the carburetor 46 where it draws in air through the intake port 47 and catalyzes in a manner similar to that of the preferred embodiment. As the cartridge 40 reaches its operating temperature the user places the mouthpiece 48 in their mouth and draws air in through the inhalation intake port 49 and through the vapor passage 50 where it is pre-cooled. [0058] FIG. 5 depicts a sectional view of the tobacco cartridge 30 . In the preferred embodiment, it consists of tobacco material 31 , enclosed in a wrapper 32 , with perforations 33 , and aeration wells 34 . The wrapped cartridge allows for the easy insertion and disposal of tobacco material without creating a mess, while the perforations allow the formed vapor to be released. When the cartridge is used up it can be easily disposed of in its entirety. [0059] Here, tobacco or tobacco material is defined as any combination of natural and synthetic material that can be vaporized for pleasure or medicinal use. As an example, one test cartridge was prepared as embodiment of the present invention using flue-cured tobacco, glycerin, and flavorings. Those skilled in the art of tobacco product manufacture are familiar with these and other ingredients used for cigarettes, cigars, and the like. The test cartridge was produced by chopping tobacco into fine pieces (less than 3 mm diameter, preferably less than 2 mm), adding the other ingredients, and mixing until even consistency was achieved. [0060] In the preferred embodiment, the cartridge is primarily cylindrical. In other embodiments, the form could be modified for various reasons. As an example, the walls of the cartridge might be drafted for easier insertion into the vaporization chamber. Or, the bottom of the cartridge might possess receptacles, which when combined with complimentary features on the surface cavity of the vaporization chamber would allow for more surface contact and hence improved thermal conduction. [0061] Any material could be used for the wrapper, provided that when heated to the operating temperature, it does not produce significant amounts of harmful gases. Aluminum foil and parchment paper are two examples. With papers, the cartridge would be manufactured in a folded-cup design, similar to that shown in FIG. 6 . With films or metal foils, the wrapper could be pressed or blow-molded to the appropriate shape. [0062] During manufacture of the preferred embodiment, the cartridge is enclosed on all sides, and perforated on the top so that vapors can emanate upwards. In the perforation step, or in an additional step, the optional aeration wells would be created. [0063] In an alternate embodiment, the cartridge might be wrapped on all sides but leaving the top exposed, as shown in FIG. 7 . This is possible since the purpose of the wrapper is primarily to prevent tobacco material from touching the sides and bottom of the vaporization chamber. [0064] In another embodiment, the material for the top of the cartridge might be vapor-permeable, such that perforations are not necessary. [0065] In another embodiment, the cartridge as purchased by the user has no openings, but is punctured prior to insertion into the device, or upon introduction to the vaporization device. The latter could be achieved by adding a hollow puncturing means to the mouthpiece part of the device. For example, the inhalation passage of the mouthpiece could be extended by a hollow tube. When the mouthpiece is reinserted to close the device, it pierces the cartridge previously introduced, and allows a path for vapor to exit to the user. [0066] In the preferred embodiment, the tobacco material is a homogenous mixture. In another embodiment, there might be two layers, as shown in FIG. 8 . The moist layer 35 has higher content of vapor-forming material than the dry layer 36 , which consists of dry tobacco or other material acting as a filter. The dry layer serves to prevent any liquid from bubbling up and out of the cartridge during heating. [0067] In another embodiment of the cartridge, a lower compartment might consist entirely of a vapor-forming medium, such as glycerine. An upper region would consist of the tobacco material to be vaporized, and the two would be separated by a material that only allows the medium to pass in a vapor or gaseous phase. Gore-tex (brand name) is one such material. In use, vapor generated in the lower region would pass through the semi-permeable membrane, volatize the active components of the tobacco, and a mix of the two would be delivered to the user upon inhalation. [0068] In another embodiment, the consistency of the tobacco material is such that the wrapper is not necessary. This is possible if at least the outer surface of the cartridge is dry and cohesive enough to not leave deposits inside the device. Such a cartridge can be made by forming tobacco material in a mold. If the resulting surface is excessively moist, it can be dried by heating the cartridge in an oven. [0069] It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.	A smoking device for generating and releasing smoking vapor free from contamination into the mouth of a user comprising a mouthpiece for providing vapor for inhalation to a user including a tubular casing containing a heater for heating a smoking substance at a substantially constant low temperature by regulating the flow of fuel by a thermal regulator and further having means for visual indication of the operation of the device.	0
FIELD OF THE INVENTION The present invention relates to intravascular stent implants for maintaining vascular patency in humans and animals and more particularly to a stent in the form of a braided stent. BACKGROUND OF THE INVENTION Percutaneous transluminal coronary angioplasty (PTCA) is used to increase the lumen diameter of a coronary artery partially or totally obstructed by a build-up of cholesterol fats or atherosclerotic plaque. Typically a first guidewire of about 0.038 inches in diameter is steered through the vascular system to the site of therapy. A guiding catheter, for example, can then be advanced over the first guidewire to a point just proximal of the stenosis. The first guidewire is then removed. A balloon catheter on a smaller 0.014 inch diameter second guidewire is advanced within the guiding catheter to a point just proximal of the stenosis. The second guidewire is advanced into the stenosis, followed by the balloon on the distal end of the catheter. The balloon is inflated causing the site of the stenosis to widen. The dilatation of the occlusion, however, can form flaps, fissures and dissections which threaten reclosure of the dilated vessel or even perforations in the vessel wall. Implantation of a metal stent can provide support for such flaps and dissections and thereby prevent reclosure of the vessel or provide a patch repair for a perforated vessel wall until corrective surgery can be performed. It has also been shown that the use of intravascular stents can measurably decrease the incidence of restenosis after angioplasty thereby reducing the likelihood that a secondary angioplasty procedure or a surgical bypass operation will be necessary. An implanted prosthesis such as a stent can preclude additional procedures and maintain vascular patency by mechanically supporting dilated vessels to prevent vessel reclosure. Stents can also be used to repair aneurysms, to support artificial vessels as liners of vessels or to repair dissections. Stents are suited to the treatment of any body lumen, including the vas deferens, ducts of the gallbladder, prostate gland, trachea, bronchus and liver. The body lumens range in diameter from small coronary vessels of 3 mm or less to 28 mm in the aortic vessel. The invention applies to acute and chronic closure or reclosure of body lumens. A typical stent is a cylindrically shaped wire formed device intended to act as a permanent prosthesis. A typical stent ranges from 5 mm to 50 mm in length. A stent is deployed in a body lumen from a radially compressed configuration into a radially expanded configuration which allows it to contact and support a body lumen. The stent can be made to be radially self-expanding or expandable by the use of an expansion device. The self expanding stent is made from a resilient springy material while the device expandable stent is made from a material which is plastically deformable. A plastically deformable stent can be implanted during a single angioplasty procedure by using a catheter bearing a stent which has been secured to the catheter such as in U.S. Pat. No. 5,372,600 to Beyar et al. which is incorporated herein by reference in its entirety. The stent must be reduced in size to facilitate its delivery to the intended implantation site. A coil stent is delivered by winding it into a smaller diameter and fixing it onto a delivery catheter. When the device is positioned at the desired site, the coil is released from the catheter and it either self-expands by its spring force or it is otherwise mechanically expanded to the specified dimension. As with many stents, the deformation of the stent when it is assembled on the delivery catheter causes a strain in the stent material. If the strain is too large the material will experience plastic deformation to such an extent that the stent will not recover to the intended dimensions following deployment. This is true of superelastic or pseudoplastic alloys such as disclosed in U.S. Pat. No. 5,597,378 issued to Jervis, which is incorporated herein by reference in its entirety. Thus a maximum allowable strain based on material is a limiting parameter in stent design. Two parameters influence the amount of strain a stent will experience during the deformation described above. The first is the degree of deformation applied to the stent and the second is the thickness of the stent material. For a given deformation, the strain experienced by a material is proportional to the thickness of the material. Since it is desirable to deliver a stent on the smallest delivery system possible it follows that the thickness of the stent material should be reduced to keep the strain within acceptable parameters. When forming a stent with a single solid strand (such a length of solid wire), a limit will be reached where the thickness of material becomes so small that the stent will meet the maximum allowable strain but will no longer have the hoop strength to provide adequate scaffolding. Current helical coil stents are delivered on the smallest profile catheter that the stent will allow. Strain on the stent during assembly on the catheter is the limiting factor with stents made from solid round or flat wire helical coil stents. U.S. Pat. No. 5,342,348 to Kaplan for “Method and Device for Treating and Enlarging Body Lumens” discloses a single helically wound strand and two counterwound delivery matrix filaments. A two stranded stent is shown in U.S. Pat. No. 5,618,298 to Simon for “Vascular Prosthesis Made of Reasorbable Material”. Mesh stents are disclosed in U.S. Pat. No. 5,061,275 to Wallsten et al. for “Self-Expanding Prosthesis”, U.S. Pat. No. 5,064,435 to Porter for “Self-Expanding Prosthesis Having Stable Axial Length”, U.S. Pat. No. 5,449,372 to Schmaltz et al. for “Temporary Stent and Methods for Use and Manufacture”, U.S. Pat. No. 5,591,222 to Susawa et al. for “Method of Manufacturing a Device to Dilate Ducts in Vivo”, U.S. Pat. No. 5,645,559 to Hachtmann et al. for “Multiple Layer Stent”, U.S. Pat. No. 5,718,169 to Thompson for “Process for Manufacturing Three-Dimensional Braided Covered Stent”. Woven mesh stents typically have warp and weft members as disclosed in U.S. Pat. No. 4,517,687 to Liebig et al. for “Synthetic Woven Double-Velour Graft”, U.S. Pat. No. 4,530,113 to Matterson for “Vascular Grafts with Cross-Weave Patterns”, U.S. Pat. No. 5,057,092 to Webster for “Braided Catheter with Low Modulus Warp” and EP 122,744 to Silvestrini for “Triaxially-braided Fabric Prosthesis”. The warp strands are typically the strands in the longitudinal direction on a prosthesis. The weft strands are typically the strands which are shuttled through warp strands to form a two dimensional array. WO 95/29646 to Sandock for a “Medical Prosthetic Stent and Method of Manufacture” discloses a geometric pattern of cells defined by a series of elongate strands extending to regions of intersection and interlocking joints at regions of intersections formed by a portion of at least one strand being helically wrapped about a portion of another. Various helical stents are known in the art. U.S. Pat. No. 4,649,922 to Wiktor for “Catheter Arrangement Having A Variable Diameter Tip and Spring Prosthesis” discloses a linearly expandable spring-like stent. U.S. Pat. No. 4,886,062 to Wiktor for “Intravascular Radially Expandable Stent and Method of Implant” discloses a two-dimensional zig-zag form, typically a sinusoidal form. U.S. Pat. No. 4,969,458 to Wiktor for “Intracoronary Stent and Method of Simultaneous Angioplasty and Stent Implant” discloses a stent wire coiled into a limited number of turns wound in one direction then reversed and wound in the opposite direction with the same number of turns, then reversed again and so on until a desired length is obtained. Braiding is a well known craft. See Braidmaking by Barbara Pegg, published by A & C Black Ltd, 35 Bedford Row, London WC1R 4JH, pp. 9-16 which is hereby incorporated by reference. It is an object of the invention to produce a stent which has the ability to tolerate greater deformations, yet has a smaller profile to permit the use of a smaller delivery system thereby reducing the amount of trauma experienced by the patient. It is a further object of the invention to produce a stent which would recover to specified dimensions with maximized radial hoop strength and resistance to lateral force. SUMMARY OF THE INVENTION The present invention is accomplished by providing an apparatus for a radially expandable stent for implantation within a body vessel, comprising one or more continuous, discrete, metal strands. At least three strands repeatedly cross over each other to form a bundle. The strands are joined at the proximal and distal end such that the strands are free to adjust their position relative to each other in response to compression forces. One or more bundles are wound together to form an elongate hollow tube. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a wound down, helical coil stent under strain; FIG. 2 is a strand with an unstrained radius curvature; FIG. 3 is a strand with a strained radius curvature; FIG. 4 is a bundle of strands; FIG. 5 is a cross-section of a four stranded bundle with worst case stacking; FIG. 6 is an helical coil stent; FIG. 7 is a detail of the helical coil stent of FIG. 6 using a four stranded cross-over braid; FIG. 8 is a cross-section of the detail of the bundle of FIG. 7; FIG. 9 is a three stranded braid; FIG. 10 is a four stranded cross-over braid; FIG. 11 is a five stranded braid; FIG. 12 is a six stranded round braid; FIG. 13 is an alternate six stranded flat braid; FIG. 14 is an eight stranded alternating braid; FIG. 15 is an eight stranded braid; FIG. 16 is an eight stranded twisted braid; FIG. 17 is a nine stranded double braid; FIG. 18 is an eleven stranded braid; FIG. 19 is an eleven stranded alternating braid; and FIG. 20 is a twelve stranded cross-over braid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS During assembly onto the delivery system (catheter), a helical coil stent 10 is deformed into a reduced diameter 30 . This deformation imposes a strain in the stent material. If the strain is too great, the stent 10 will experience plastic deformation to such an extent that the stent will not recover dimensionally to the specified size during deployment. When a stent 10 is reduced to a given catheter diameter 30 the strain experienced by the stent 10 material is proportional to the thickness 35 of the stent material. The present invention applies to any helical coil stent 10 where deformation is limited by the applied strain. The stent 10 is formed of multiple strands 15 . Each strand is continuous and discrete. Multiple strands 15 of material are formed into a bundle 40 , each strand 15 having a fine thickness. The resulting hoop strength of the stent 10 formed of one or more bundles 40 will be the cumulative strength of all of the strands 15 in the bundle(s) 40 . The strain on the other hand, will be limited to that of a single strand 15 . By using multiple fine strands 15 which are formed into a bundle 40 , the required strength of the stent 10 can be maintained, while allowing the increased stent 10 to be deformed (wound down) onto a smaller diameter delivery catheter than would otherwise be possible with a single solid strand 15 stent material. Bundles 40 can be formed by braiding or by other means to enable the strands 15 to slide relative to one another when compressed or released; this is necessary to reduce friction. One or more bundles 40 are then formed into the elongate hollow tubular stent 10 . The increased deformation capacity of multiple strands 15 which are formed into a bundle 40 is possible because strain is proportional to a single strand 15 thickness, not the thickness of the bundle 40 of strands 15 . The width of the braided bundle 40 of strands is significantly greater than that of a round wire. Multiple strands 15 braided together into a bundle 40 provide support to one another, providing resistance to lateral forces as well as to crushing forces. By increasing the number of strands 15 in the braid, the width can be increased resulting in greater lateral strength. The increase in the number of strands 15 also provides increased radial or “hoop” strength. The braided wire coil stent 10 provides a means to deliver a decreased profile stent while still providing accurate deployment thereby resulting in a less traumatic stent 10 delivery. When a smaller delivery catheter is needed and the strain on a strand 15 increases, stent 10 deformation will increase when assembling the stent 10 onto a smaller delivery catheter. With a single strand 15 , such as a length of wire, a limit will be reached where the following parameters can be optimized no further and the strand 15 thickness can no longer realistically be reduced. These parameters include the delivery catheter size, the hoop strength, the lateral strength. The preferred number of strands 15 would be unique from one stent application to another. Any number of three or more strands would be possible. A larger diameter 20 stent 10 would generally require more strands 15 than a smaller diameter 20 stent 10 to provide adequate radial and hoop strength. Depending on the anatomy being targeted, a stent 10 might require more strands 15 to increase the resistance to compression, as in a stent 10 intended for implantation in the popliteal artery. Some stents 10 might require fewer strands 15 to minimize the amount of blood contact with metal. Others, such as a biliary stent would require more strands 15 or a flatter braid pattern to provide total coverage of the orifice being stented to prevent tissue in-growth. The balloon expandable stent 10 can be made of a round wire or of a flat wire using a springy, inert, biocompatible material with high corrosion resistance that can be plastically deformed at low-moderate stress levels. Acceptable materials include tantalum, stainless steel or elgiloy. The preferred embodiment for a self-expanding stent 10 includes superelastic (nickel titanium) NiTi such as Nitinol manufactured by Raychem or Forukawa. Any of the braided patterns could be made from a round wire or from a flat wire. FIGS. 4-5 and FIGS. 7-20 depict braided stents of 3 - 6 strands, 8 - 9 strands, and 11 - 12 strands with alternative 6 (FIGS. 12 and 13 ), alternative 8 (FIGS. 14 and 16) and alternative 11 (FIGS. 18 and 19) stranded embodiments. Those skilled in the art would recognize that these examples are not the only braided patterns that could be used for the bundle of strands stent concept. Potentially any braid pattern could be used, as for example, a seven or a ten stranded braid. Preferably, the braid is a flattened braid which is formed into a stent 10 with a flat side of the braid forming the stent cylinder so as to minimize the delivered profile of the stent and to maximize the luminal diameter of the stent. To braid multiple strands 15 , conventional ribbon braiding equipment can be used. After braiding, the helical coil stent 10 could be formed by affixing the ends of the desired length of strands 15 to each other and wrapping the braided bundle 40 around a conventional mandrel to form the desired diameter 20 . The ends can be affixed with any welding technique such as, plasma welding, laser welding, RF welding or TIG welding. In addition, brazing, soldering or crimping could be employed to affix the stent ends to each other. By heat treating the assembly the helical coil shape can be “memory set” into the braided bundle 40 . The following applies whenever devices are deformed and is not limited to stents 10 . Stents 10 are placed in a strained state (see FIGS. 1 and 3) during the assembly process where the stents 10 are taken from a free unstrained state (see FIGS. 6 and 2) and are wound onto a delivery catheter 105 at a much smaller diameter. As a braided bundle 40 is formed into a helical coil, the strands 15 may shift with respect to each other. Induced strain is higher when strands 15 stack exactly on top of each other as in FIG. 5 and less if the strands are offset as in FIG. 4 . Strain is highest at the inner edge of the stent coil while in the assembled state (see FIG. 1) and can be represented by the following equation: Strain=(d(R 1÷ R 2 −1))÷(2R 1 −d) where: R 1 is the unstrained radius of curvature 25 R 2 is the strained radius of curvature 30 d is the wire strand 35 thickness (wire diameter depending on whether the strand is round or flat) as opposed to the overall stent 10 diameter. Three stent designs will be mathematically approximated to, for the smallest diameter stent 10 that can be wound down on a delivery catheter without exceeding the 8% strain permitted with Nitinol as the metal. These examples show that the smallest delivery profile achievable is that of a braided multi strand 15 stent 10 . All three stents have a nominal outer diameter of 9 mm (0.354 inches) and it is assumed will provide adequate hoop and lateral strength. The material in each example is Nitinol which has a maximum 8% allowable strain. EXAMPLE I The first example is a helical coil stent 10 formed from a single member round 0.013 inch wire. A 9 mm outer diameter 20 stent 10 requires a round wire with a minimum diameter of 0.013 inches to provide the necessary hoop strength and lateral stiffness. The applied strain is 8%. For this stent 10 design, the unstrained radius of ad curvature 25 is 0.1705 inches and the outer diameter of the strand 15 is 0.013 inches. Solving the equation for R 2 ,=R 1 ÷[[ε÷d] (2R 1 −d)+1]the strained radius of curvature 30 is therefor 0.0565 inches. Solving the equation for D=2R 2 +d, where D is the outer diameter 20 of the helical coil stent 10 and d is the wire strand thickness or diameter 35 , yields a stent outer diameter 20 of 0.126 inches. With the maximum stent 10 outer diameter 20 profile of 0.126 inches, the required introducer size is at least 9.6 French. The delivery of the device would require an introducer sheath or a guide catheter large enough to accommodate the maximum stent 10 outer diameter 20 profile of 0.126 inches or 9.6 French. The stent 10 would therefor pass through a delivery catheter 105 with a 10 French inner diameter of 0.131 inches. EXAMPLE II The second example is a 9 mm outer diameter 20 helical coil stent 10 formed from a single strand 10 of 0.008 inch×0.025 inch flat wire. This size wire is wide enough to provide lateral stability which is lost when the thickness of the wire is reduced to 0.008 inches. Using the same method as for the Example 1 round wire above, the unstrained radius of curvature 25 is 0.173 inches and the outer diameter 20 is 0.008 inches. Solving the equation for R 2 =R 1 ÷[[ε÷d](2R 1 −d)+1], the strained radius of curvature 30 is therefor 0.087 inches. Solving the equation for D=2R 2 +d, where D is the outer diameter 20 of the helical coil stent 10 and d is the wire strand thickness or diameter 35 , yields a stent outer diameter 20 of 0.087 inches. With the maximum stent 10 outer diameter 20 profile of 0.087 inches, the required introducer size is at least 6.6 French. Due to differences in the wire forming process, the flat wire can only withstand a 7% strain. With a 7% applied strain the maximum device profile is 0.095 inches with a required 7.3 French introducer size. The applicant has been unable to achieve acceptable shape memory results with a strain greater than 7% for flat wire stents. The stents did not return to the nominal diameters following deployment as they were undersized, a function of the flattening process during the raw wire manufacture. With an 8% applied strain, the maximum stent device outer diameter 20 profile is 0.067 inches, with at least a 5.1 French introducer size. EXAMPLE III The third example is a helical coil stent 10 formed from multiple braided 0.005 inch strands 15 , as for example five strands 15 seen in FIG. 4 or four strands 15 seen in FIG. 5 . Then, R 1=( 0.354/2)−3r=(0.354/2 — −3(0.0025)=1.1695 inches. R 2 =0.267 the outer diameter, D=2(R 2 =3r)=0.0684 inches. This corresponds to approximately a 5.2 French introducer. Braided bundles 40 can be of any number of strands. FIG. 9 is a three stranded braid. Each strand 15 could be a bundle 40 with one to four or more strands. FIG. 10 is a four stranded cross-over braid. Each strand 15 could be a bundle 40 with one to four or more strands. FIG. 11 is a five stranded braid. FIG. 12 is a six stranded round braid. FIG. 13 is a six stranded flat braid. FIG. 14 is an eight stranded alternating braid. FIG. 15 is an eight stranded braid. FIG. 16 is an eight stranded twisted braid. FIG. 17 is a nine stranded double braid. FIG. 18 is an eleven stranded braid. The eleven stranded FIG. 19 is an eleven stranded alternating braid which is braided in the same pattern as the eight stranded FIG. 14 but using three additional strands. Any number of strands, however, could be used in this alternating pattern. FIG. 20 is a twelve stranded cross-over braid made with four bundles 40 with three strands 15 each and braided in the pattern of FIG. 10 . Any number of strands could be used in the bundle(s). The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, however, that other expedients known to those skilled in the art or disclosed herein, may be employed without departing from the scope of the appended claims. No. Component 10 Stent 15 Strand 20 D - Outer Diameter of Stent 25 R 1 - Unstrained Radius of Curvature 30 R 2 - Strained Radius of Curvature 35 d - Wire Strand Thickness 40 Bundle 45 Strand 1 50 Strand 2 55 Strand 3 60 Strand 4 65 Strand 5 70 Strand 6 75 Strand 7 80 Strand 8 85 Strand 9 90 Strand 10 95 Strand 11 100 Strand 12 105 Delivery Catheter 110 First Bundle 115 Second Bundle 120 Third Bundle 125 Fourth Bundle	A radially expandable stent for implantation within a body vessel, comprising one or more continuous, discrete, metal strands. At least three strands repeatedly cross over each other to form a bundle. The strands are joined at the proximal and distal end such that the strands are free to adjust their position relative to each other in response to compression forces. One or more bundles are wound together to form an elongate hollow tube.	0
PRIORITY [0001] This application claims priority under 35 U.S.C. § 119 to an application entitled “System and Method for Controlling Traffic Distribution in a Mobile Communication System” filed in the Korean Intellectual Property Office on Jan. 11, 2003 and assigned Serial No. 2003-1874, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to a traffic control system and method in a mobile communication system, and in particular, to a system and method for controlling reverse traffic. [0004] 2. Description of the Related Art [0005] Generally, in a mobile communication system, data transmission can be divided into forward data transmission and reverse data transmission. “Forward data transmission” refers to data transmission from a base station to a mobile station, while “reverse data transmission” refers to data transmission from a mobile station to a base station. According to the type of transmission data, mobile communication systems can be classified into systems supporting only a voice service, systems supporting a combination of a voice service and a simple data service, and systems supporting only a high-speed data service. The advent of such a mobile communication system providing a data service is the result of rapid development of mobile communication technology in answer to increasing users' demands for transmitting/receiving more information at higher speeds. [0006] In such a mobile communication system processing data at high speed, reverse data traffic is transmitted over a packet data channel by the physical layer packet (PLP), and a length of the data traffic is fixed. Packets have a variable data rate, and a data rate of each packet is determined depending on power of a mobile station, an amount of transmission data, and a rate control bit (RCB) transmitted from a base station over a rate control channel (RCCH). [0007] In addition, a data rate of a mobile station is determined by scheduling. A base station performs scheduling using RoT (Rise over Thermal) representing total reception power over thermal noises or a load obtained from a received signal-to-noise ratio of a mobile station belonging to a current base transceiver system (BTS). When RoT is available, scheduling is performed so that RoT is matched to a predetermined reference RoT level, and when RoT is unavailable, scheduling is performed so that a load is matched to a predetermined reference load level. For the convenience of explanation, RoT is used herein. [0008] Thus, a scheduler in a base station determines whether to increase, decrease or hold a data rate of a corresponding mobile station, considering RoT, and a buffer status and a power status of each mobile station. [0009] [0009]FIG. 1 is a diagram for explaining the configuration and operation scheme for controlling a mobile station in an existing system. As illustrated in FIG. 1, a base station (BS) is comprised of base transceiver systems (BTSs) and a base station controller (BSC). A BTS manages its cell(s), and a BSC is connected to a plurality of BTSs and controls the BTSs connected thereto. In addition, as illustrated in FIG. 1 , each mobile station undergoes reverse data rate control from a BTS to which it belongs. A mobile station in a non-soft handover (non-SHO) state (hereinafter referred to as “non-SHO mobile station”) undergoes reverse data rate control from only a BTS to which it belongs, while a mobile station in a soft handover (SHO) state (hereinafter referred to as “SHO mobile station”) undergoes reverse data rate control from a plurality of BTSs in an active set. Herein, a non-SHO mobile station refers to a mobile station in a non-SHO state, while an SHO mobile station refers to a mobile station in an SHO state. In FIG. 1, mobile stations 111 and 113 each belonging to one BTS are controlled by their BTSs 101 and 102 , respectively, and another mobile station 112 belonging to both BTSs becomes an SHO mobile station which is simultaneously controlled by the BTSs 101 and 102 . [0010] In an SHO mobile station controlled by a plurality of BTSs, reverse rate control messages received from the BTSs are different from each other. In this regard, a rate control procedure will now be described with reference to FIG. 1. A BTS# 1 101 and a BTS# 2 102 each transmit a rate control command to a mobile station according to their RoT conditions. For example, BTS# 1 101 can send a rate-down command to the mobile station, while BTS# 2 102 can send a rate-up command to the mobile station. In this case, the mobile station obeys a command from any one of the BTSs, and commonly, according to ‘Or-of-Down’ rule, the mobile station decreases it data rate if any one of the BTSs issues a rate-down command. This is because a scheduler in each BTS determines a data rate of each mobile station so that a received RoT maintains a reference RoT, and if a mobile station receiving a rate-down command increases its data rate, a received RoT of a corresponding BTS will undesirably exceed the reference RoT. [0011] When a received RoT exceeding the reference RoT in a particular BTS, an increase in an interference level may occur, resulting in a reduction in throughput of a corresponding cell. Therefore, in order to secure stability of the entire system, if a mobile station receives different rate control commands from a plurality of BTSs, the mobile station determines whether there is any rate-down command among the received rate control commands. If there is any rate-down command, the mobile station decreases the current data rate and transmits data at the decreased data rate. [0012] However, even the use of the ‘Or-of-Down’ rule cannot resolve the inefficiency problem. A scheduler in a BTS determines a data rate of each mobile station so that a received RoT maintains a reference RoT. However, if a mobile station receiving a rate-up command from a particular BTS decreases it data rate, a received RoT of the BTS becomes lower than a reference RoT. This means that available resources are not sufficiently utilized, also leading to a reduction in throughput of a corresponding cell. [0013] Similar situations occur even in a case where reverse Hybrid Automatic Repeat and Request (HARQ) is used. A description will now be made of an operation performed in such a case. If reverse data is received, a BTS must transmit an ACK or NACK signal to a mobile station over an acknowledgment channel (hereinafter referred to as “ACK channel”). In the case where the mobile station is a non-SHO mobile station, a corresponding BTS determines an ACK or NACK signal and then transmits the determined signal. However, in the case where the mobile station is an SHO mobile station, signals received from respective BTSs connected to the mobile station can be different from each other. This will be described below with reference to FIG. 1. For example, BTS# 1 101 can successfully receive a packet transmitted by the mobile station 112 , while BTS# 2 102 fails to receive the packet transmitted by the mobile station 112 . In this case, BTS# 1 101 transmits an ACK signal to the mobile station 112 and BTS# 2 102 transmits a NACK signal to the mobile station 112 . The mobile station 112 receiving such signals transmits the next packet because it received from BTS# 1 101 an ACK signal indicating successful receipt of a previous packet. However, BTS# 2 102 expects that the previous packet will be retransmitted, since it failed to successfully receive the previous packet, i.e., it transmitted a NACK signal to the mobile station 112 . In this case, a signal for determining whether each cell has successfully received a packet is needed between BTS# 1 101 and BTS# 2 102 . However, such signaling can act as an overhead. That is, when BTS# 1 101 transmits ACK and BTS# 2 102 transmits NACK, the mobile station 112 transmits a new packet since it received ACK, but BTS# 2 102 expects retransmission of the previous packet. Therefore, for more accurate operation, it is necessary to inform BTS# 2 that BTS# 1 transmitted ACK, through signaling via a network. SUMMARY OF THE INVENTION [0014] It is, therefore, an object of the present invention to provide a system and method for controlling traffic distribution so as to increase BTS efficiency during traffic control in a BTS and a BSC in a mobile communication system. [0015] It is another object of the present invention to provide a system and method for transmitting a consistent control message to a mobile station in a mobile communication system. [0016] It is a further object of the present invention to provide a system and method for efficiently controlling an SHO mobile station. [0017] It is yet another object of the present invention to provide a system and method for increasing throughput of a BTS by transmitting a consistent control message to a mobile station in a mobile communication system using reverse HARQ. [0018] To achieve the above and other objects, there is provided a system for controlling a reverse data rate in a mobile communication system including a plurality of mobile stations, a plurality of base transceiver systems (BTSs) in communication with the mobile stations, and a base station controller (BSC) connected to the BTSs. The BSC detects handover states of the mobile stations, and controls a reverse data rate of a mobile station in a handover state. The BTS controls a reverse data rate of a mobile station in a non-handover state. [0019] To achieve the above and other objects, there is provided a method for controlling a reverse data rate of a mobile station by a base station controller (BSC) in a mobile communication system including a plurality of mobile stations, a plurality of base transceiver systems (BTSs) in communication with the mobile stations, and the BSC connected to the BTSs. The method comprises the steps of transmitting a reverse rate control suspend message for a particular mobile station to a BTS controlling a reverse data rate of the mobile station when handover of the mobile station is needed; and controlling a reverse data rate of the mobile station considering remaining capacity of BTSs in communication with the mobile station among BTSs included in an active set of the mobile station. BRIEF DESCRIPTION OF THE DRAWINGS [0020] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which: [0021] [0021]FIG. 1 is a diagram for explaining the configuration and operation scheme for controlling a mobile station in an existing system; [0022] [0022]FIG. 2 is a block diagram illustrating control function blocks for explaining operations of BTSs and a BSC during rate control on an SHO mobile station and a non-SHO mobile station according to a preferred embodiment of the present invention; [0023] [0023]FIG. 3 is a flowchart illustrating a procedure for performing handover of a mobile station in a BTS control function block according to a preferred embodiment of the present invention; [0024] [0024]FIG. 4 is a flowchart illustrating a procedure for performing handover of a mobile station in a BSC control function block according to a preferred embodiment of the present invention; and [0025] [0025]FIG. 5 is a block diagram illustrating structures of a BTS apparatus and a BSC apparatus according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0026] A preferred embodiment of the present invention will now be described in detail with reference to the annexed drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness. [0027] In an embodiment of the present invention, a BSC performs rate control in an SHO state and rate control in a non-SHO state in a different manner. That is, rate control on an SHO mobile station is performed by a BSC, while rate control on a non-SHO mobile station is performed by BTSs. In the following description, the present invention will be applied to rate control. One of ordinary skill in the art will recognize that the invention can also be applied to response signal control. For this, a reverse control message is used. The reverse control message is classified into a rate control bit (RCB) which is a reverse rate control bit, and a grant message. The reverse rate control bit can be transmitted to instruct increase, decrease or hold of the current rate, or to instruct increase or decrease of the current rate. On the other hand, the grant message can be transmitted to instruct a corresponding mobile station to perform reverse control at a certain rate from the next slot. For example, if a mobile station, currently performing reverse transmission at 9.6 Kbps, receives a grant message granting transmission at 38.4 Kbps, the mobile station can perform reverse transmission at 38.4 Kbps, skipping the next rate of 19.6 Kbps. In the following description, RCB is used for reverse rate control. However, the grant message can also be used for reverse rate control. [0028] In addition, a response signal (or ACK/NACK signal) can be included in the reverse control message. In some cases, a message received from a SHO mobile station via a particular BTS is good while a message received from the SHO mobile station via another BTS is bad. In this case, a BSC transmits an ACK signal, a response signal indicating ‘Good’ reception, to the SHO mobile station. A description of such an example will be made below. [0029] [0029]FIG. 2 is a block diagram illustrating control function blocks for explaining operations of BTSs and a BSC during rate control on an SHO mobile station and a non-SHO mobile station according to a preferred embodiment of the present invention. With reference to FIG. 2, a detailed description will now be made of control functions and other functions of BTSs and a BSC during rate control on an SHO mobile station and a non-SHO mobile station according to the present invention. [0030] Respective reverse control function blocks 201 , . . . , 20 N of BTSs (hereinafter referred to as “BTS control function blocks”) perform reverse rate control on non-SHO mobile stations. Such rate control is performed in the existing method where a BTS controls a data rate of a mobile station. Therefore, signaling and call assignment on a non-SHO mobile station are performed by the BSC like in the existing method. However, the BTS control function blocks 201 , . . . , 20 N according to the present invention are designed not to perform reverse rate control on an SHO mobile station. A control function block 210 of a BSC (hereinafter referred to as “BSC control function block”) controls BTSs in the existing method. In addition, the BSC control function block 210 performs reverse rate control on an SHO mobile station according to the present invention. That is, the BSC control function block 210 controls a data rate of an SHO mobile station and controls transmission of a signal transmitted over an ACK channel. [0031] A detailed description will now be made of operations of the BTS control function blocks 201 , . . . , 20 N and the BSC control function block 210 when a mobile station transitions from a non-SHO state to an SHO state. [0032] When a mobile station is in a non-SHO state, i.e., when it belongs to only one BTS, the BTS control function block 201 allows the corresponding mobile station to undergo reverse data rate control only from that BTS. That is, the BTS control function block 201 generates a rate control bit and an ACK bit, and transmits them to the mobile station. However, various functions such as call-in, call-out, signaling, data rate control, and ACK/NACK detection from a received signal, are controlled by a BSC like in the existing method. [0033] In the meantime, if the mobile station transitions to an SHO state, the BTS control function block 201 generates information on a handover action time and an active set of a mobile station, and transmits the generated information to the corresponding mobile station. In addition, since subsequent control is performed by the BSC, the BSC control function block 210 determines whether assignment of a new rate control channel is needed. At the same time, the BSC control function block 210 determines whether assignment of an ACK channel is necessary. As a result of the determinations, if new channels are needed, the BSC control function block 210 generates new rate control channel information and new ACK channel information, and sends the generated channel information to the mobile station. Since the BTS control function block 201 cannot know the states of other BTSs, the BSC control function block 210 determines whether to assign new channels, and if assignment of new channels is required, the BSC control function block 210 controls the BTS so as to set up new channels to the mobile station transitioning to the SHO state. In other words, the BTS forms a message using handover action time information, active set information and new channel assignment information received from the BSC control function block 210 , and transmits the formed message to the corresponding mobile station. As a result, new channels are assigned between the BTS and the mobile station. [0034] Next, a description will be made of a control operation when the SHO mobile station enters the area of a particular BTS, ending its SHO state. When the SHO mobile station enters the area of a particular BTS, i.e., when handover is ended, the BSC control function block 210 instructs a corresponding BTS control function block to which the mobile station belongs to individually control a reverse data rate of the mobile station. A description will now be made of an operation performed in such a case. [0035] A delay time of a control message transmitted to a mobile station that undergoes reverse data rate control from the BSC control function block 210 is different from a delay time of a control message transmitted to a mobile station that undergoes reverse data rate control from a BTS. When a mobile station receives reverse rate control information from a BSC, a delay of about 2 frames occurs. Here, the “frame” becomes a data transmission unit for the reverse rate control information transmitted over a forward rate control channel. Therefore, when the mobile station is subject to reverse data rate control from the BSC, an ACK/NACK signal transmitted over an ACK channel may suffer transmission failure. For example, assuming that a BTS generates and transmits an ACK/NACK signal in answer to a signal received from a mobile station within a time of 2 frames (or 1 frame), if the BTS transmits a NACK signal responsive to data received at a current time (time #1) to the mobile station at a particular time (time #2), the mobile station retransmits a corresponding frame at a time #3 in response to the NACK signal received. The time #1, the time #2 and the time #3 occur in sequence. Therefore, each of the times can be either a transmission time in an air state, or a time required when determining a type of received information after completing error check on a received frame. [0036] However, since the SHO mobile station is subject to reverse data rate control from the BSC, a longer delay time occurs than when the mobile station undergoes reverse data rate control by the BTS. Actually, a time delay of at least 1 frame occurs when a signal is transmitted from a mobile station to a BSC via a BTS and then a NACK signal responsive to the corresponding signal is generated by the BSC and transmitted to the mobile station via the corresponding BTS. That is, if the BSC generates a NACK signal in response to a reception signal transmitted 1 frame ahead of the current time (or time #1) and transmits the generated NACK signal to a corresponding mobile station, the mobile station retransmits a corresponding frame at the time #3. In this case, if handover has ended, the BSC transmits an ACK/NACK signal to the mobile station in response to a previous frame, and the corresponding BTS controls a data rate of the mobile station from the time when handover ended. Therefore, when the BSC transmits an ACK/NACK signal to the mobile station in response to a frame received at a previous time, the BTS transmits an ACK/NACK signal in response to a frame received after handover ended. In this case, the mobile station receives retransmission requests for different data frames at the same time, so the ACK/NACK signal received from the BSC collides with the ACK/NACK signal received from the BTS. [0037] Generally, a delay time of a control message transmitted when a mobile station is controlled by a BSC is longer than that of a control message transmitted when the mobile station is controlled by a BTS. Therefore, if a mobile station transitions from a non-SHO state to an SHO state, a transmission time of an ACK/NACK signal becomes longer. In this case, the ACK/NACK signal is normally transmitted regardless of whether the mobile station is assigned a new channel or uses an existing channel. However, if the mobile station transitions from the SHO state to the non-SHO state, a transmission time of an ACK/NACK signal becomes shorter. Therefore, if the existing channel is used, the BTS and the mobile station both should transmit ACK/NACK signals for two packets at the same time, which is undesirable. [0038] In this case, in the embodiment of the present invention, packet transmission is suspended for a period as much as a difference in a transmission time of the ACK/NACK signal between the BTS and the BSC. In an alternative method, when the mobile station transitions from the non-SHO state to the SHO state, the BTS assigns a new ACK channel to the corresponding mobile station. In this way, a response (ACK/NACK) signal generated while the mobile station undergoes data rate control from the BSC is transmitted over an ACK channel assigned when the mobile station undergoes data rate control by the BTS, and a response signal for a new packet is transmitted over an ACK channel newly assigned by the current BTS. In the latter method, the mobile station has two ACK channels corresponding to a transmission delay time between the BTS and the BSC, and the BTS must hold the two ACK channels assigned to the mobile station. [0039] A description will now be made of an operation of the BSC control function block 210 according to above-stated two embodiments of the present invention. The BSC control function block 210 performs a general control function. In an SHO state, when an inquiry about whether assignment of a new channel to an SHO mobile station is needed is received from the BTS control function block 201 , the BSC control function block 210 checks a state of target BTSs to which a call is to be handed over, and then sends the result information to the inquiring BTS. In addition, if a reverse rate control request for the SHO mobile station is received from the BTS control function block 201 , the BSC control function block 210 controls a data rate of the SHO mobile station considering a resource state of the corresponding BTSs. Furthermore, the BSC control function block 210 symbol-combines packets received from the mobile station via a source BTS that will hand over a current call and target BTSs to which the call is to be handed over, and checks whether the combined received packet is good or bad. If the received packet is good, the BSC control function block 210 transmits an ACK signal over an ACK channel set up between each BTS in the handover operation and the mobile station, and if the received packet is bad, the BSC control function block 210 transmits a NACK signal over the ACK channel set up between each BTS in the handover operation and the mobile station. [0040] Thereafter, if handover of the mobile station has ended, the BSC control function block 210 transmits an ACK/NACK signal for the packet received from a corresponding mobile station to the mobile station over a channel that was set up during handover. In a first embodiment of the above-stated two embodiments, the BSC control function block 210 controls a BTS so as to suspend reverse data transmission between the BTS and the mobile station for a predetermined time. Unlike this, in the second embodiment, the BSC control function block 210 transmits an ACK/NACK signal over a separate channel instead of a channel which was in the handover operation, as a channel for ACK/NACK transmission between the mobile station and the BTS. After an ACK signal for a final frame received from the BSC is transmitted, the channel is released. However, the channel transmitting an ACK/NACK signal, set up between the BTS currently controlling the mobile station and the BSC, is continuously held. The BSC control function block 210 instructs the BTS control function block 201 to control a reverse data rate of the handover-ended mobile station. [0041] When the BSC controls a data rate of an SHO mobile station in this way, a BTS subtracts capacity corresponding to a data rate of a corresponding mobile station from the total capacity and controls a data rate of mobile stations in its area based on RoT or load at the remaining capacity, thus contributing to an increase in throughput of the BTS. In addition, BTSs are prevented from transmitting different ACK/NACK signals to the SHO mobile station, contributing to an increase in BTS efficiency and making it possible to easily control the mobile station. [0042] As a BSC controls an SHO mobile station, a mobile station is not separately controlled by a plurality of BTSs included in its active set, and receives the same signal from the BTSs by the BSC. Therefore, it is possible to increase reception capability of packet data and an ACK/NACK channel signal through soft-combining on the received signals. [0043] [0043]FIG. 3 is a flowchart illustrating a procedure for performing handover of a mobile station in a BTS control function block according to a preferred embodiment of the present invention. [0044] In step 300 , the BTS control function block 201 measures the total RoT or a load of a BTS. The total RoT can be measured at a predetermined time, and the load can be calculated by the BTS depending on a state of the current reverse link. Therefore, when the load is used for control, the BTS control function block 201 continuously measures the load, and when control is performed based on RoT, the BTS control function block 201 measures the RoT every predetermined time. [0045] When measurement of RoT is completed or calculation of a load is completed, the BTS control function block 201 proceeds to step 302 . In step 302 , the BTS control function block 201 receives a reverse load of a mobile station controlled by a BSC because handover is in progress. The reverse load is a value received from a BSC, and the BSC provides this information to the BTS continuously or at stated periods. Therefore, in step 304 , the BTS receiving the reverse load calculates reverse loads of non-SHO mobile stations, i.e., mobile stations whose reverse data rates are controlled by the BTS control function block 201 according to the present invention. [0046] Thereafter, the BTS control function block 201 proceeds to step 306 . In step 306 , the BTS control function block 201 calculates capacity of a currently available reverse link from the value determined in steps 300 to 304 . In addition, the BTS control function block 201 controls a reverse data rate of a non-SHO mobile station controlled by a BTS according to the currently available reverse link. Furthermore, in step 306 , the BTS control function block 201 transmits a response (ACK/NACK) signal for a reverse packet received from a mobile station. The BTS control function block 201 determines in step 308 whether a message indicating occurrence of a handover state for a mobile station controlled by the BTS is received from the BSC. If it is determined in step 308 that there is a mobile station in an SHO state, the BTS control function block 201 proceeds to step 310 where it excludes the corresponding mobile station from mobile stations whose reverse rates are being controlled. That is, reverse rate control by the BTS is suspended. Thereafter, the BTS control function block 201 returns to step 300 , and measures RoT or a load. When the BTS control function block 201 operates based on RoT, if the current time is not a predetermined RoT measurement time, the BTS control function block 201 proceeds to step 302 without performing the measurement of RoT or a load. In this manner, rapid reverse rate control can be performed on a mobile station in communication with only a BTS. Also, at step 308 , if it is determined that there are no mobile stations in an SHO state, the process returns to step 300 . [0047] Meanwhile, though not illustrated in FIG. 3, when a particular mobile station controlled by a BSC enters a particular BTS, there is a case where reverse rate control should be performed on the mobile station. In this case, the BTS measures RoT or load of the corresponding mobile station during RoT measurement or load measurement of step 300 , and performs reverse rate control on the mobile station. In addition, for such a rate control time, a separate channel can be used or a method of suspending reverse transmission for a predetermined time can be used. [0048] [0048]FIG. 4 is a flowchart illustrating a procedure for performing handover of a mobile station in a BSC control function block according to a preferred embodiment of the present invention. [0049] In step 400 , the BSC control function block 210 holds a call control state. Here, “call control state” refers to a state in which transmission of call assignment and control messages for a mobile station is controlled through a BTS, and according to the present invention, reverse rate control for a non-SHO mobile station is not included. For such mobile stations, reverse rate control is performed in the BTS as described in conjunction with FIG. 3. Holding such a call control state, the BSC control function block 210 proceeds to step 402 where it determines whether there is a mobile station in an SHO state. If it is determined in step 402 that there is a mobile station in an SHO state, the BSC control function block 210 proceeds to step 404 , and otherwise, the BSC control function block 210 returns to step 400 . [0050] In step 404 , the BSC control function block 210 transmits a call handover (or call transfer) message to the BTS. That is, the BSC control function block 210 transmits to a corresponding BTS a message for suspending reverse rate control on a mobile station controlled by the BTS. Furthermore, in step 404 , the BSC control function block 210 determines an active set and a handover action time of the mobile station to be handed over (i.e., an SHO mobile station). Thereafter, in step 406 , the BSC control function block 210 determines whether assignment of a reverse rate channel and an ACK channel for transmitting an ACK/NACK signal is needed for the SHO mobile station. If it is determined in step 406 that channel assignment is necessary, the BSC control function block 210 proceeds to step 408 , and otherwise, the BSC control function block 210 proceeds to step 410 . [0051] In step 408 , the BSC control function block 210 assigns new channels to the SHO mobile station, and transmits a channel assignment message via a BTS currently in communication with the mobile station in order to inform the mobile station of the newly assigned channels. [0052] Thereafter, in step 410 , the BSC control function block 210 controls a reverse data rate of the SHO mobile station considering states of BTSs in communication with the SHO mobile station among BTSs included in the active set of the SHO mobile station. At this point, an ACK/NACK signal received from the mobile station is also transmitted to the BSC without being processed in the BTS. Therefore, the BSC control function block 210 performs data retransmission or new data transmission depending on information received from the mobile station. [0053] As the SHO mobile station is controlled by the BSC, the mobile station can receive a consistent ACK signal, and since the mobile station receives the same message, the mobile station can increase reception probability by soft-combining the received message. [0054] After performing rate control on a reverse link of a particular mobile station in step 410 , the BSC control function block 210 proceeds to step 412 where it determines whether handover of the SHO mobile station is ended. That is, the BSC control function block 210 determines whether the mobile station enters the area of a particular BTS and performs communication only in the BTS. If it is determined in step 412 that handover is ended, the BSC control function block 210 proceeds to step 414 where it generates a control handover (or control transfer) message for instructing a BTS where the mobile station is located to perform reverse rate control, and delivers the generated control handover message. Therefore, if handover of the mobile station is ended, transmission control on a reverse rate and an ACK signal is handed over to another BTS by the particular BTS. After the step 414 , the BSC control function block 210 returns to step 400 . At step 412 , if it is determined that handover has not ended, the process returns to step 410 . [0055] Next, with reference to FIG. 5, a description will be made of the connection between a BTS apparatus and a BSC apparatus, and their internal structures. FIG. 5 is a block diagram illustrating internal structures of a BTS apparatus and a BSC apparatus according to a preferred embodiment of the present invention. [0056] In FIG. 5, reference numeral 510 represents an internal structure of a BSC apparatus, and reference numeral 520 represents an internal structure of a BTS apparatus. It should be noted that only the essential elements associated with the present invention are shown in FIG. 5. [0057] First, a description will be made of internal structure and operation of the BSC 510 . A controller 511 of the BSC 510 includes the BSC control function block 210 described in connection with FIG. 2, and thus performs a control operation according to the present invention. Data needed in the controller 511 is stored in a memory 512 . That is, the memory 512 stores data needed for performing the procedure of FIG. 4. In addition, the memory 512 stores various data necessary for controlling an SHO mobile station. Using such data, the controller 511 generates a message for controlling a corresponding mobile station, or a message for controlling a corresponding BTS. A data processor 514 divides forward data to be transmitted to a particular mobile station in a proper size, or combines data received from the mobile station to transmit it to an upper layer. An interface 513 performs interfacing on data exchanged between the BSC 510 and the BTS 520 . [0058] Next, a description will be made of internal structure and operation of the BSC 520 . The BTS 520 includes an interface 522 for performing interfacing on data received from the BSC 510 , and a controller 521 for performing a control operation according to the present invention. The controller 521 includes the BTS control function block described in connection with FIG. 2. Thus, the controller 521 performs reverse control on only a non-SHO mobile station. Even when reverse control is performed by the BSC 510 , a message is actually transmitted from the BTS 520 to a mobile station. Therefore, when a request for transmission of a control message for an SHO mobile station is received from the BSC 510 , the controller 521 generates a control message. Alternatively, however, the BSC 510 can directly generate such a message and transmit the generated message. [0059] A switch 523 performs a switching operation for transmitting forward data to be transmitted to each mobile station or reverse data received from each mobile station to the interface 522 , and transmitting data received from the controller 521 to the BSC 510 . In some cases, the switch 523 can be implemented with dedicated lines. However, it is implemented herein with a general switch. Data to be transmitted to a particular mobile station is processed in a modem section 524 and a radio frequency (RF) section 525 . The processed data is transmitted to a mobile station via an antenna. The modem section 524 and the RF section 525 include N modems 524 - 1 to 524 -N and N RF modules 525 - 1 to 525 -N, respectively, and each modem-RF module pair is associated with its corresponding mobile station. The modem section 524 encodes and modulates data to be transmitted in a forward direction, and demodulates and decodes data received in a reverse direction. The RF section 525 performs up-conversion and power amplification to transmit forward transmission data to a corresponding mobile station, and performs low-noise amplification and down-conversion on reverse reception data to generate a baseband signal. The modem section 524 and the RF section 525 constitute a packet transceiver. During handover of a mobile station, the BSC 510 and the BTS 520 perform the control operation described in connection with FIGS. 2 to 4 , so a detailed described thereof will be omitted for simplicity. [0060] As described above, mobile stations are divided into a mobile station whose handover is performed by the BSC and a mobile station whose handover is not performed by the BSC, to control reverse traffic on a distributed basis. In this case, the same control information can be transmitted to the mobile station. In addition, rate control on an SHO mobile station and transmission of a signal for HARQ become simple. Moreover, a non-SHO mobile station undergoes reverse rate control from a BTS, thus contributing to rapid rate control. [0061] While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.	A system for controlling a reverse data rate in a mobile communication system including a plurality of mobile stations, a plurality of base transceiver systems (BTSs) in communication with the mobile stations, and a base station controller (BSC) connected to the BTSs. The BSC detects handover states of the mobile stations, and controls a reverse data rate of a mobile station in a handover state. The BTS controls a reverse data rate of a mobile station in a non-handover state.	7
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control of the closing sequence of two wings or leaves of windows, doors or the like which are closeable by means of a door-closing device each. 2. Description of the Related Art The two wings or leaves of doors, windows or the like mentioned above are a moving wing to be opened first and a resting wing to be opened subsequently. Each door closing device attached to a wing is equipped with a guide roller or the like which is mounted on a pivotable sliding arm and is horizontally guided on a fixed frame. The two wings are rotatably hinged to opposite vertical sides of a frame. If the wings are equipped as usual with projecting edges, one of the wings must always be closed before the other, so that the projecting edges can engage in each other and the second wing can be closed without being obstructed by the projecting edge of the first wing. In doors having two wings, one of the doors is usually kept closed and, therefore, is called the resting wing, while the other door is continuously opened and closed or may also be held in an open position for a period of time and, therefore, is called the moving wing. Both doors are provided with a door closing device of known construction which, unless the doors are locked, return the doors after they are released into the closed position. If a locking device is provided, this locking device must be manually or automatically released prior to closing, so that the door closing device can carry out its closing function. When the doors are smoke and fire protection doors, such a locking device can be automatically released in the case of fire by means of an appropriate monitoring unit. It must be ensured particularly in this case that the closing sequence of the two doors is absolutely maintained because the doors could otherwise not be completely closed. One of the doors, particularly the moving wing, can be closed up to a position which is relatively close to the closed position, however, the door must then be maintained in this position until the other wing, i.e., the resting wing, has assumed its closed position. Hereinbelow, it is assumed that it is always the resting wing which must be closed before the moving wing. Arrangements for controlling the closing sequence of two doors which are each closable by means of a door-closing device are already known. A door-closing device is understood to be a conventional device which always acts on the wing in the swinging closing direction and whose force becomes effective when no other forces act on the open or partially open wing in opening direction and when no holding forces act on the wing and when the wing is also not locked. Such door-closing devices may be mounted in the upper as well as the lower end of the door. An arrangement for controlling the closing sequence of wings, also called closing sequence regulator, must not only safely close the doors in a predetermined sequence, but must also meet certain aesthetic requirements. In addition, the arrangement should be as much as possible protected against damage, particularly against intentional damage. Furthermore, the closing sequence regulator must operate as safely as possible, particularly when the doors are fire or smoke protection doors. For example, a closing sequence regulator has been known in which a hydraulic valve in the bypass line of the door-closing device is controlled through the resting wing. However, such devices are frequently not safe enough in their operation because leaks in the hydraulic system cannot be avoided absolutely safely and because of the sensitivity of the control elements in the case of fire. It is, therefore, the primary object of the present invention to provide a closing sequence regulator in which the above-described disadvantages are avoided and to further develop the above-described arrangement in such a way that hydraulic units are avoided and, consequently, the operational safety is increased. In addition, the arrangement should be robust, inexpensive to manufacture and easy to assemble. SUMMARY OF THE INVENTION In the arrangement for controlling the closing sequence of two wings of windows, door or the like which are each closable by means of a door-closing device, each door-closing device is equipped with a guide roller or the like which is mounted on a pivotable sliding arm and is guided on a fixed frame, or each door-closing device has an element, particularly a hydraulic piston, which is displaceable by the swinging movement of the door. The improvement provided by the present invention resides in the following features A locking member which is movable by the opening movement of the resting wing into the return end region of the moving wing guide roller or by a roller or the like of the moving wing which is fixedly connected to the slidable element. The sliding member can be actuated parallel to the wing plane by means of a sliding member which is adjustable horizontally and parallel to the plane of the fixed frame. The sliding member is provided with or connected to a locking element of a locking device. The locking element is slidable against the force of a restoring spring by the opening movement of the resting wing guide roller or the roller or the like of the resting wing. A spring-biased control lever supported on the sliding member is arranged between the locking element and the resting wing guide roller or the roller or the like of the resting wing. The control lever projects into the initial displacement region of the resting wing guide roller or the roller or the like of the resting wing and the pivoting movement of the control lever is released only in the locking position of the locking member. A spring-biased locking piece of the locking device is held in an ineffective position in the initial position of resting wing guide roller or the roller or the like of the resting wing and the locking piece can be disengaged by the return end movement of the roller. The first embodiment of the arrangement according to the present invention is used in connection with door-closing devices which have a pivotable sliding arm and which are connected to the door in the case of a door-closing device mounted at the top of the door. The sliding arm of the door-closing device is moved along the fixed frame and usually has at its free end a guide roller or the like which is moved along the upper horizontal beam when the door is opened or closed. The guide roller is preferably guided in an appropriate rail which is mounted on the crossbeam of the fixed frame. An appropriate sliding element can also be used instead of the guide roller. The horizontal movement of the guide roller or the like along the crossbeam of the fixed frame during opening of the door and the movement in the opposite direction during closing of the door can be utilized for controlling the closing sequence. If the moving wing is to be opened first and the resting wing is to be opened next, the moving wing can be easily opened and closed in the known manner even when the control arrangement is present. However, when the resting wing is opened with the moving wing being open or at least partially open, wherein the moving wing must be at least opened to such an extent that projecting edges of the two wings can be moved past each other, the opening of the resting wing results in a corresponding sliding movement of the guide roller of its door-closing device toward the axis of rotation of the resting wing. Of course, the guide roller of the moving wing travels toward the axis of rotation of the moving wing when the moving wing is opened. When the resting wing is opened, the guide roller of the resting wing causes an adjusting movement of the locking member from the ineffective position into a locking position. The locking position is determined such that, when the moving wing is closed prior to the closing or at least prior to the complete closing of the resting wing, the moving wing is held in an open position which makes possible the complete closing of the resting wing without interference by the projecting edges of the wings. When the resting wing is closed, the guide roller of its door-closing device also assumes the initial position. At the end of the return movement of the guide roller, the guide roller moves the locking piece against the resistance of its spring in unlocking direction. This results in a release of the sliding member which can return into its initial position because of the restoring spring acting on it. The return movement of the sliding member automatically causes the turn of the locking member into its ineffective position. As a result, the obstacle for the guide roller of the door-closing device on the moving wing is removed and this door-closing device can now completely close the moving wing. When the resting wing is improperly opened before the moving wing, this also leads to a corresponding sliding movement of the sliding member in the above-described manner and the attendant movement of the locking member in the direction towards its locking position. In this position, the locking member acts on the guide roller of the door-closing device of the moving wing and causes by means of the latter and the corresponding sliding arm an opening of the moving wing. Since the locking device on the resting wing has in the meantime started to operate, the locking member remains in its locking position until the entire arrangement begins to operate in the described manner by means of the closing end movement of the resting wing. The arrangement according to the present invention has the advantage that it operates entirely mechanically. As a result, the arrangement is substantially more robust than an arrangement operating hydraulically. The assembly of the arrangement is simpler because no hydraulic lines are required. Thus, the arrangement is also less expensive. The locking device composed of the locking element of the sliding member and of the locking piece which is fixed to the blind frame but spring-biased and slidable locks the return movement of the sliding member until it is released, so that it forms a locking and locating device. The control lever may be mounted directly or indirectly in the sliding member. The control lever is spring-biased toward the guide roller. Accordingly, when the control lever is pivoted by the guide roller, the spring acting on the lever is tensioned or its tension is increased. The locking member and locking element are coupled and operationally connected through the sliding member in such a way that the pivoting movement of the control lever into a released position for the guide roller resting against it is released only when the locking member is in its locking position, since a release of the guide roller on the resting wing by the control lever causes the displaced sliding member to be prevented in its return movement by the locking device. As a result, the correct closing sequence of the two wings is ensured even when the resting wing is further opened during which opening the guide roller is moved away from the control lever. As soon as the guide roller is released from the control lever, the resting wing can be opened further, can be fixed in the open position and can again be closed when necessary or desired. In accordance with the present invention, the spring-biased locking piece is held particularly by means of the guide roller in an ineffective position when the resting wing guide roller is in its initial position. In this situation, the spring acts on the locking piece. As soon as the controller releases the locking piece, which may occur already after a short opening movement of the resting wing, the spring presses the locking piece against the locking element which results in the locking action. The locking element preferably is constructed in such a way that locking in several locking positions of the sliding member is possible. The second embodiment of the present invention relates particularly to a closing device which is mounted at the floor. When the wing to which the door-closing device is attached is swung, an element of the door-closing device is displaced along a straight line; the element may particularly be a damping piston with which such door-closing devices are equipped. The movement of the piston can be conducted, for example, through a lateral arm to a position of the housing at which the elements of the arrangement of the present invention required for the control of the closing sequence of the two wings can be accommodated. The lateral arm may support the above-described roller, a pin or a similar component. When this roller or the like carries out during opening and closing of the door a movement which corresponds to the movement of the resting wing guide roller or of the moving wing guide roller, it is readily apparent that the elements of this roller can be arranged exactly in the same manner as is the case in the illustrated embodiment of the moving wing guide roller 14 and the resting wing guide roller 15. Consequently, the movements and control operations are carried out in the same manner as in the first embodiment. Of course, in the case of a door-closing device mounted at the floor, the sliding member is also mounted at the floor and it must be appropriately protected and securely mounted in the floor. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there is illustrated and described a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWING In the drawing: FIG. 1 is a schematic view of the upper ends of two closed door wings in a fixed frame with the arrangement according to the present invention for controlling the closing sequence of the doors; FIG. 2 is a top view of the wings of FIG. 1, the closed position of wings being indicated by solid lines and the open position by broken lines; FIG. 3 is a partial view of the arrangement on a larger scale, partially in horizontal direction; FIG. 4 on an even larger scale, a portion of the left half of FIG. 1 with closed wing; FIG. 5 is a corresponding view with the left wing partially open; FIG. 6 a corresponding illustration of the right portion of FIG. 3 with the wing being closed; FIG. 7 a corresponding view with the right wing being partially open; FIG. 8 shows, on an even larger scale, a structural component of FIG. 1; FIG. 9 is a sectional view along sectional line IX--IX of FIG. 8; and FIG. 10 is a vertical sectional view of the upper wing end and the fixed frame in the region of a door-closing device. DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1 of the drawing, two doors are hinged to a fixed frame 1. Usually only the left door is opened and, for this reason, is called the moving wing 2. Because the right wing remains usually closed, it is called the resting wing 3. The moving wing 2 is attached by means of at least two hinges 4 arranged one above the other on the left vertical beam of the fixed frame 1, while the resting wing 3 is attached by means of hinges 6 to the right vertical beam 7 of the fixed frame 1. The two wings have at least at their free vertical sides a projecting edge 8 and 9, respectively. When the wings are closed, the projecting edges rest against each other. As can be easily seen from FIG. 2, the resting wing 3 cannot be completely closed when the moving wing 2 is closed too far or already completely closed. For this reason, the arrangement described below ensures that the resting wing 3 is always closed before the moving wing 2. The moving wing 2 is closed by means of a door-closing device 10 of known construction. A door-closing device 11 of preferably the same construction is used for closing the resting wing 3. In the illustrated embodiment, door-closing devices mounted at the top of the doors are used. These door-closing devices are constructed as so-called sliding arm door-closing devices. However, the present invention cannot only be used in door-closing devices of this type, but they may rather also be used as door-closing devices at the bottom of the door. As illustrated in FIG. 2 in broken lines, sliding arm door-closing devices are attached to the door 2 or 3 and they each have a sliding arm 12 or 13. Each sliding arm has at its free end a sliding roller 14 or 15 or the like which can also be seen particularly well in FIG. 10 and in FIG. 3. Each door-closing device may also include a displaceable element, for example, a hydraulic piston 85, schematically illustrated in FIG. 2. While the sliding arm has a position when the door is closed which is approximately parallel or slightly inclined to the plane of the door, the sliding arm is pivoted relative to the plane of the door when the door is opened. As a result, the sliding roller is moved toward the hinge side of the door. Thus, when the wing 2 is opened, the sliding roller is moved parallel to the transverse beam of the fixed frame in the direction of arrow 16, while the sliding roller 15 of the resting wing 3 is moved in the direction of arrow 17. The partially or completely opened door can be fixed or locked in its position in an open manner, by means of a locking device integrated in the door-closing device. When the partially or completely open door is released, the door is closed in the direction of arrow 18 in the case of moving wing 2 and in the direction of arrow 19 in the case of resting wing 3. If, as shown in FIG. 2, the resting wing 3 is opened farther than the moving wing 2, the closing movement of the wing 2 ends by means of the arrangement according to the present invention when the position illustrated in FIG. 2 is reached. In this position, the projecting edge 9 of the resting wing 3 can still be moved past the projecting edge 8. The sliding rollers 14 and 15 are usually guided during opening and closing of the wings in a guide rail 20 or 21 which, when the door-closing device is mounted at the top of the door, is attached to the upper transverse beam of the fixed frame 1, usually by being placed on the frame. The guide rails are divided into two chambers 23 and 24 by means of a central wall 22. The outer chamber 24 forms the longitudinal guidance for the slide roller 14 or 15. The inner chamber 23 serves to accommodate the essential elements of the arrangement for controlling the closing sequence. The essential elements of the arrangement for controlling the closing sequence of the two wings 2 and 3 are a locking member 25, a sliding member 26 and a locking device 27. A control lever 28 is another important element. The locking member 25 has a circular arc-shaped back side 29 which rests against a receiving portion of a guide member 30 having the same shape, for example, having the shape of a slot. The guide member 30 is fastened to the guide rail 20 at the left end thereof, as can be seen in FIG. 3. Thus, the back side 29 slides on the circular arc-shaped support surface 31 of the guide member 30. Thus, the locking member is a rotating member whose rotating movement is limited by a circular arc-shaped guide slot 32 of the locking member 35 and a guide bolt 33 engaging in the slot 32. The guide bolt 33 is held in the guide member 30. The locking member 25 has at its upper end as seen in FIG. 3 a driving bolt 34 which extends transversely of the plane of the locking member 25 and projects on both sides thereof. In the position of rotation of the locking member 25 shown in FIG. 8, the driving bolt 34 rests against a wall 35 of the sliding member 26 which wall 35 extends transversely of the plane of the Figure. An arched end 36 of the locking member 25 rests in the region of the driving bolt 34 against a pressure piece 37 against which, in turn, rest two concentrically arranged springs 38 and 39. The springs are helical compression springs. The left end of the springs as seen in FIG. 9 rest indirectly against the sliding member 26 through a bracing member 14. A rotation of the locking member 25 from the locking position shown in FIG. 5 to the initial position shown in FIG. 4 results in a tensioning of the springs 38 and 29. A third spring is attached at the inner end of the pressure piece 37. This third spring forms a restoring spring 41 for the sliding member 26. The right end of the restoring spring 41 visible in FIG. 4 is attached to a bolt 42 of the guide rail 20. When the restoring spring 41 pulls the sliding member 26 which is in the right position in FIG. 5 back into the initial position shown in FIG. 4, the wall 35 presses against the driving bolt 34 and thereby causes a return rotation of the locking member 25 in the direction of arrow 43. A damping device 44 is formed by the springs 38 and 39 with the pressure piece 37. The lower end 45 of the approximately sickle-shaped locking member 25 as seen in FIG. 4 surrounds with a circular arc-shaped edge 46 the sliding roller 14 of the door-closing device 10. When the door is opened, the sliding roller 14 moves out of the edge 46. When the locking member 25 is in the locking position as seen in FIG. 5, the sliding roller 14 arising in the direction of arrow 47 can only be moved until it makes contact with the lower end 45. Any impact occurring during this closing procedure of the moving wing is absorbed by the damping device 44. However, the sliding roller 14 can rotate the locking device 25 in the direction of arrow 43 when the sliding member 26 is released for displacement in the direction of arrow 48. This return movement of the sliding movement 36 is locked by the locking device 27 seen in FIG. 3 until the resting wing 3 is closed. The sliding member 26 is composed at least essentially of two sliding member parts 59 and 50 which are arranged in axial alignment with each other and which are coupled through a preferably longitudinally adjustable intermediate member 51. Into the illustrated embodiment, the sliding member part 49 is arranged in the guide rail 20 and the sliding member part 50 in the guide rail 21. Each of these two sliding member parts may include additional components, however, these are not of significance. The intermediate member may be a cable, a connecting rod or the like. To be able to exactly adjust the distance between the two sliding member parts 49 and 50, a longitudinal adjusting device 52 is arranged, for example, on the intermediate member 51. The longitudinal adjusting device 51 may be of known construction, for example, as shown in FIG. 3. The sliding member part 50 of the resting wing includes a locking element 53 of the locking device 27. As illustrated, for example, in FIG. 6, the locking element 53 is integrally connected to sliding member part 50. The locking element 53 advantageously has the shape of a rack with sawtooth-like toothing. The locking element 53 interacts with a spring-biased locking piece 54 which is slidable in the direction of double arrow 55 transversely of the longitudinal axis of the outer chamber 24 of the guide rail 21 in which the locking element 53 is mounted. The spring for biasing the locking piece 54 is denoted by reference 56. The locking piece 54 has a tooth 57 which can enter into the tooth gaps of the locking element 53. However, as shown in FIG. 6, the tooth 57 does not engage the tooth gaps of the locking element 53 because the sliding roller 15 prevents it from doing so. However, once tooth 57 engages the locking element 53, the sliding member part 50 can be moved in the direction of arrow 58 but cannot be moved back in the opposite direction. A sliding movement of the sliding member part 50 and, thus, of the entire sliding member 26 against the direction of arrow 58 is only possible when the tooth 57 has previously been disengaged from the toothing of the locking element 53. To be able to adjust the tooth 57 relative to the locking element 53 in longitudinal direction, the locking piece 54 is slidably mounted on an adjusting member 59 which can be adjusted relative to the end piece 61 by means of a control member 60 which is composed of a threaded spindle. The control member 60 is rotatably but non-slidably mounted in the adjusting member 59 and can be screwed into a thread 62 of the end piece 61. For guiding the sliding member part 50 in the inner chamber 23 of the guide rail 21, the sliding member part 50 has a longitudinal slot 63 which is engaged by a guide bolt 64 and extends in longitudinal direction of the guide rail 21. Parallel to the longitudinal slot 63 is provided a receiving means 65 for a compression spring 66 which is constructed as a helical spring. The left end of the spring rests against a blind end 4 of the receiving means 65 while the right end of the spring rests against a first level arm 68 of the control lever 28, particularly with the intermediate arrangement of a pressure member 67. The control lever 28 is rotatably mounted on the sliding member part 50 by means of a bearing axis 69. The bearing axis is preferably located at the free end of the sliding member part 50 in the region of the right end of the locking element. The compression spring 66 holds the control lever 28 in the position shown in FIG. 6 when the resting wing is closed. In this position, the arc-shape edge 70 of the control lever 28 surrounds the sliding roller 15. The control lever 28 further has a wedge-shaped projection 71 forming an outer inclined contact surface 72 and an inner inclined pressure surface 73. As is easily apparent, the sliding roller 15 which is located to the right of the wedge-shaped projection 71 when the resting wing is open can pivot the control lever 28 through the inclined contact surface 72 against the resistance of the compression spring 66 in the direction of arrow 75. In the same manner, in case of a sliding movement directed against the direction of arrow 74, the sliding roller 15 can also pivot the control lever 28 in the direction of arrow 75 by means of the inclined pressure surface 73. A particularly bolt-shaped guide element 76 is mounted on the control lever 28. The guide element 76 extends parallel to the control lever 28 and is mounted laterally spaced from the bearing axis 29. The guide element 76 engages in a guide slot 77 which may be located in a plane below or above the pivoting plane of the control lever 28. In the illustrated embodiment, this guide slot is provided in the guide rail 21, particularly in the bottom of the inner chamber 23. The guide slot includes a middle portion 78 which extends straight, i.e., parallel to the longitudinal axis of the guide rail and two diverging guide portions 79 and 80 which are inclined relative to the middle portion 78 and are directed towards the fixed frame 1, as can be seen in FIG. 6. As a result, the control lever 28 cannot be turned in the direction of arrow 75 when the guide element 76 is in the middle portion 78 of the guide slot. Thus, if an opening movement of the resting wing causes the slide roller 14 to be moved against the direction of arrow 74 in a manner to be described below, the control lever 28 remains in its initial position until the bolt-like guide element 76 reaches the inclined side portion 76 which is directed inwardly and to the right. A pivoting movement in the direction of arrow 75 is subsequently possible and this means that the sliding roller 15 is released from the arc-shaped edge 70 and is moved along the wedge-shaped projection 71 of the control lever 28. As FIG. 6 of the drawing shows, when the resting wing is closed, the guide element 76 is approximately at the transition of the side portion 80 in the middle portion 78 If, due to a manipulation of the device after releasing the locking device 27, the sliding member 26 is in its left initial position but the sliding roller 15 is to the right of the wedge-shaped projection 71, locking of the sliding roller 15 with the control lever 28 in the closing position of the resting wing is possible because the guide element 76 can move into the side portion 80. The spring 65 subsequently pivots the control lever 28 into the initial position shown in FIG. 6. It should be added that, during normal operation and with the resting wing 3 being opened, the control lever 28 maintains its upwardly pivoted position illustrated in FIG. 7. Accordingly, the sliding roller 15 interacts with the inclined contact surface 72 only when the device is manipulated or, to a limited extent, when due to tolerances the wedge-shaped projection 71 projects somewhat into the path of movement of the returning sliding roller 15. When during closing of the resting wing the sliding roller 15 arrives at the locking piece 54, its shape in conjunction with a correspondingly extending inclined pressure surface 81 causes an unlocking movement of the locking piece 54 in the direction of arrow 82. Subsequently, the force of the restoring spring 41 which concentrically extends through the springs 38 and 39, become effective and, with the resting wing 3 now being closed, the restoring spring 41 can pull the sliding member 26 towards the left into the initial position, which also pivots the locking member 25 back into its initial position. This makes possible the final closing movement of the sliding roller 14 of the moving wing 2 which causes the latter also to be closed by means of a door-closing device. It should be added that the second lever arm of the control lever 28 which supports the guide element 76 is denoted by reference numeral 83. From the above description of the individual components, the manner of operation of the arrangement of the invention is relatively easy to understand. When both wings are closed and the moving wing is to be opened, this can be done easily in the conventional manner because there is no obstacle to the necessary displacement movement of the sliding roller 14 of the door-closing device 10 of the moving wing, as is clear from FIG. 4. Consequently, the moving wing can also be easily closed. If the resting wing is opened after the moving wing has previously opened, sliding roller 15 of the door-closing device 11 takes along the sliding member through the control lever 28 in the direction of arrow 58, as shown in FIG. 6. As soon as the sliding roller 15 has moved away from the locking piece 54 of the locking device 27 to a sufficient extent, the tooth 54 is engaged in the locking element 53. The latter and the sliding member 26 can still be moved further in the direction of arrow 58, but they cannot be moved back in the opposite direction. As a result, the locking member 25 which during the displacement of the sliding member 26 had been pivoted into a locking position remains in the locking position shown in FIG. 3. When the moving wing is closed before the resting wing, this is only possible until the sliding roller 14 makes contact with the locking member 25. The resulting inclined position of the moving wing 2 shown in FIG. 2 makes it possible to subsequently close the resting wing 3. When this occurs, the locking device 27 is released in the described manner and the locking member 25 is pivoted by the sliding member 26 from the final displacement range of the sliding roller 14, so that the door-closing device 10 can now close or finish closing the resting wing. The components of the arrangement are mounted protected in the guide rails, so that they usually are not damaged and can also usually not be damaged intentionally or rendered inoperative. This also results, of course, in a positive aesthetic effect. As already mentioned, the arrangement operates safely even when it is unintentionally or intentionally incorrectly operated. When manipulations are carried out on the arrangement, the components can essentially not be damaged, so that the operation is always ensured. When the locking device is released, the locking member 25 is returned to the initial position by means of spring 41, so that the force of the spring in the door-closing device is fully available for obtaining the final position of the moving wing. Thus, it is possible to overcome the forces which are necessary, for example, for operating a trap. The release of the locking device is independent of the width of the door wings. It is merely necessary to adjust the length of the connection between the locking device and the locking member 25. As already mentioned, the arrangement of the invention can also be used with door-closing devices which are mounted at the bottom of the door. In that case, the longitudinal movement in the system of the door-closing device, for example, in the damping piston, is utilized for the control. The locking device or the locking member 25 can be accommodated in the door-closing device. It should be added with respect to the construction of the arrangement that the travel distance of the drive bolt 34 on the locking member 25 is smaller than the travel distance of the corresponding sliding roller 14. In addition, a separate insert 84 can be mounted in the inner chamber 23 of the guide rail 21 in which insert 84 is slidably mounted the sliding member part 50 on the side of the resting wing. In that case, the guide slot 77 is provided on this insert 84 or additionally on this insert. When it is attempted to close the moving wing by applying force when the resting wing 3 is open, this force is absorbed by the damping device 44. Subsequently, the force of the spring again opens the moving wing to such an extent that the correct closing sequence is ensured. While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.	An arrangement for controlling the closing sequence of two wings of windows, doors, and the like, especially smoke or fire protection doors, which are closable by means of a door-closing device each. The two wings are a moving wing to be opened first and a resting wing to be opened subsequently, so that projecting edges of the doors which face each other come into contact with each other in the correct sequence. A control device is actuated primarily by the slide rollers of the door-closing device of the resting wing when the resting wing is opened. With the use of a control lever and a sliding member displaced by the control lever toward the axis of rotation of the resting lever, a locking member is pivoted into the return end region of the guide roller of the door-closing device of the moving wing. This locking member locks the final closing movement of the moving wing until the resting wing has been closed. The sliding member is maintained with the aid of a locking device in a swung-out position until the resting wing has again been closed. The guide roller of the door-closing device of the resting wing releases the locking device.	4
BACKGROUND OF THE INVENTION Silicon wafers are manufactured for use in integrated circuits. During the fabrication process the wafers are often transported and stored between various process steps. Protecting the wafers from damage or contamination during the manufacturing process and storage is of paramount importance. Silicon wafers are carried, transported and stored in wafer carriers as disclosed in the prior art, a typical example of which includes U.S. Pat. No. 3,961,877. The wafer carrier that holds the fragile silicon wafers is stored and/or transported inside of a securable storage box. The securable storage box reduces both breakage and contamination of the silicon wafers. The securable wafer storage box is preferably opened and closed by automated machinery during the manufacture or delivery process, and also must be accessible manually. SUMMARY OF THE INVENTION The present invention is a latch for a silicon wafer storage box. The wafer storage box must be secured by a functional and convenient latch. The present invention encompasses such a functional, convenient latch adaptable for either manual or automated manipulation. Prior art latches have only been marginally usable with automatic machinery for opening and closing such wafer storage boxes. An object of the invention is to provide a latch capable of manipulation and release by automated machinery or by a person manually. Another object of the invention is the provision of a new and improved latch of relatively simple and inexpensive construction and operation, which is safe, durable, and performs consistently in conjunction with a silicon wafer storage box, without fear of damage to property, equipment, and/or injury to persons. A feature of the invention is a rigid upper tab having a peg adapted for engagement with a robot arm mechanism of automated machinery. Another feature of the invention is a curved resiliently flexible bight having a horizontally extending rigid lower tab, adapted for manual manipulation in releasing the latch invention while affixed to a wafer storage box in a closed position. An advantage of the invention is the flexibility of the latch which permits convenient, efficient manipulation either by a person or by automated machinery. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational environmental view of the wafer storage box showing the hinge, latch, and partial robot arm with hook. FIG. 2 is an enlarged detail section view through the box showing the latch in a closed position. FIG. 3 is an enlarged detail section view through the box showing the latch detached from the keeper tilted downward with the bight of the latch lying against the front face of the base of the wafer storage box. FIG. 4 is a detail elevation view at 4--4 of FIG. 2. FIG. 5 is a detail section at 5--5 of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT One form of the invention is illustrated and described herein. The latch is indicated in general by the numeral 10. The latch 10 is preferably used with a silicon wafer storage box indicated in general by the numeral 11. Preferably, there are two latches 10 for each storage box 11. The storage box 11 contains a cover 12 and a base 13. A keeper 14 is molded into the cover 12 for interaction with each latch 10. Latch mountings 15 are molded or affixed to the base 13 at two locations for interaction with each latch 10 A total of four latch mountings 15 will be molded or affixed to the base 13 for a complete wafer storage box system. (See FIGS. 1, 2, 5). The latch mountings 15 are substantially rectangular in shape providing rigid engagement between the latch 10 and the silicon wafer storage box 11. The latch 10 is preferably of one-piece molded construction of a material that simultaneously provides resilient flexibility and rigidness. An example of such a material is carbon filled polycarbonate plastic. The latch 10 may be released from a closed position as shown in FIGS. 1 and 2 by mechanical manipulation through the use of a robot arm 17.5. The latch 10 contains a catch portion 160 as a principal portion thereof. The catch portion 160 includes a catch 16 which interacts with the keeper 14, fastening the cover 12 to the base 13. The catch 16 is preferably hook shaped but may only need a detent in some cases. The interaction between the catch 16 and the keeper 14 locks the box 11 in a closed position. The latch 10, keeper 14, latch mountings 15, and catch 16 will vary in size depending upon the dimensional requirements of the corresponding silicon wafer storage box 11 known in the art. The catch portion 160 includes an upper operating tab 17. The upper tab 17 is of rigid construction providing strength to the latch 10 when manipulated by either a person, or by a robot arm 17.5. The upper tab 17 contains an elongated connector peg 18. The elongated connector peg 18 is located adjacent to the catch 16. The connector peg 18 preferably traverses the entire width of the upper tab 17 extending beyond the edges 19 of the upper tab 17. (See FIG. 4) The connector peg 18 extends beyond the edges of the upper tab 17 providing two ends for convenient engagement by a robot arm 17.5. The connector peg 18 is preferably cylindrical. The length and diameter of the cylindrical connector peg 18 will be sufficient to interact efficiently with either a claw or bar type robot arm 17.5 of an automated assembly process. The connector peg 18 is of rigid construction, thereby preventing the bending or fracture of the peg 18 during manipulation by the robot arm 17.5 in the releasing/locking of the silicon storage box 11. The upper operating tab 17 may contain an upturned end 20 opposite the catch 16. The upturned end 20 provides for convenient grasping of the tab 17 by an individual during manual manipulation of the latch 10. The upper operating tab 17 is preferably molded to a depending resiliently flexible upright body 21. The upright body 21 will flex when a force is applied to either the connector peg 18 or the upper tab 17. The flexibility of the upright body 21 will assist in the releasing and locking of the catch 16 to the keeper 14 as desired for opening and closing of the storage box 11. A lower operating tab 22 is preferably molded to the bottom of the upright body 21. The lower tab 22, like the upper tab 17, is of rigid construction. The lower tab 22 may contain a downturned end 23 providing increased convenience to an individual in grasping the tabs 17, 22 during manual manipulation of the latch 10. The upper and lower tabs 17, 22, including the turned ends 20, 23 respectively, remain in a confrontational relationship to each other. Supports 24 are molded between the upright body 21 and the upper tab 17, lower tab 22, and curved bight 25. The supports 24 are molded to the upright body 21, upper tab 17, lower tab 22, and curved bight 25 substantially equidistant between the edges 19 of the upright body 21. The molded supports 24 facilitate in maintaining rigidity of the upper and lower tabs 17, 22, while simultaneously not inhibiting the flexibility of the upright body 21. The curved bight 25 is preferably an an edgewise U-shape, and is molded along the lower open end to the lower tab 22. The opposite end 25.1 of the curved bight 25 is molded to a pair of pivot portions 26. The curved bight 25 is resiliently flexible. During the releasing and locking of the latch 10 relative to the cover 12, the curved bight 25 and the upright body 21 will flex. During a releasing manipulation of the latch 10 the curve of the bight 25 will constrict, thereby providing slack for the catch 16 to be pulled and moved upward and away from the keeper 14, whereby release of the latch 10 from a locked position will occur. The curved bight 25 will also constrict while the upper tab 17 and catch 16 are manipulated together in order to affix the latch 10 into a locked configuration. Molded to the opposite end 25.1 of the curved bight 25, at two locations, are pivot portions 26. Each pivot portion 26 is generally rectangular in shape and contains a pivot pin 27. The pivot pins 27 are located centrally on the exterior surfaces of the pivot portions 26 proximal to the latch mountings 15 of the base 13. As seen in FIG. 5 the pivot portions 26 are offset equidistant inside the sides 19 of the latch 10. The pair of pivot portions 26 are preferably centrally spaced and molded to the curved bight 25, such that, the pair of pivot portions 26 may be inserted for flush contact between the exterior surface of the pivot portions 26 and the interior surfaces of the latch mountings 15. The pivot portions 26 are of a sufficient length to maintain an open space between the pivot portions 26 and the base 13 while the latch 10 is in a locked position as seen in FIG. 2. The pivot portions 26 provide rigid strength sufficient to prevent flexing or bending of the upper end of the curved bight 25 during the releasing/locking manipulation of the latch 10. The pivot portions 26 provide for swingable engagement between the latch 10 and the base 13 of the silicon wafer storage box 11. The pivot portions 26 in conjunction with the pivot pins 27 provide the mechanism for positioning of the latch 10 in either the opened or locked configuration. In order to mechanically manipulate the latch 10, while locked in a closed position as seen in FIG. 2, a robot arm 17.5 will engage the two protruding ends of the connector peg 18 from below. The robot arm 17.5 will lift the connector peg up and back away from the cover 12. This movement will simultaneously cause flexing of the curved bight 25 and a slight oscillation of pivot portions 26. The hook of the catch 16 will then release upward and away from the keeper 14, whereon elevation of the connector peg 18 may be terminated and release the connector peg 18 by the robot arm 17.5 may occur. The latch 10 may then return to a relaxed configuration as seen in FIG. 3. In the relaxed configuration the upright body 21 is slightly bowed in a convex configuration, with the catch 16 in a closer proximity to the curved bight 25 than while the latch 10 is affixed in a locked position as seen in FIG. 2. The slightly bowed configuration of the body 21 assists in maintaining the latch 10 in a locked position as seen in FIGS. 1, 2 and 4. In order to manually manipulate the latch 10, while locked in a closed position as seen in FIG. 2, a person will grasp the upper and lower tabs 17, 22 near the ends 20, 23 and apply constricting force to move the tabs 17, 22 and the ends 20, 23 toward each other. The flexible upright body 21 will then bend while the tabs 17, 22 remain resilient. The hook of the catch 16 will then release upward and away from the keeper 14 whereon constricting pressure to the tabs 17, 22 may be terminated. The latch 10 will then return to a relaxed configuration as seen in FIG. 3. Alternately, in some instances the latch may be manually operated by manually lifting the ends of peg 18, either to close the latch or to open the latch. In all events care must be taken to avoid tipping the container 11 during opening or closing of the latch. In the relaxed configuration the upright body 21 is slightly bowed in a convex configuration, with the catch 16 in a closer proximity to the curved bight 25 than while the latch 10 is affixed in a locked position as seen in FIG. 2. The slightly bowed configuration of the body 21 assists in maintaining the latch 10 in a locked position as seen in FIGS. 1, 2, and 4. Upon release of the latch 10 from a locked position as see in FIGS. 2, 3 the latch will initially swing up and away from the storage box cover 12 and will then descend downward and backward, via the pivot pins 27 and pivot portions 26, until the exterior surface of the curved bight 25 rests against the base 13 and the latch mountings 15. (FIGS. 2, 3). The exterior surface of the curved bight 25 and/or the exterior surfaces of the base 13 or latch mountings 15 may contain a bumper in order to facilitate the positioning of the latch 10 while the latch 10 remains in an unlocked or rest position. The latch 10 is preferably constructed such that the weight of the catch 16, upper tab 17, connector peg 18, and upright body 21, with the assistance of gravity, will shift the curved bight 25, via the pivot portions 26 and pivot pins 27, to a relaxed position. In this relaxed position the curved bight 25 remains in flush contact with the base 13 and the mounting tabs 15. (FIG. 3) The position of the latch 10 while located in the locked position (FIG. 2) or in the rest position (FIG. 3) will provide two preset locations for the connector peg 18. The two preset locations for the connector peg 18, are easily recognizable by, or programmable into, a robot arm as part of an automated machinery process. The two preset positions of the connector peg 18 facilitate the automated manipulation of the opening/locking of the latch 10 in the automated process. When the latch is locked, the connector peg 18 is located in a position substantially horizontal to and forward of the cover 12. When the latch 10 is released, the connector peg 18 is located in an alternative position which is lower, substantially forward of, and horizontal to the latch mounting 15 of the base 13. A pivot pin 27 fits precisely into and interacts with the pivot openings 28 located in the latch mountings 15. (FIG. 2) The junction between the pivot pins 27 and the openings 28 permit swingable engagement between the latch 10 and the silicon wafer storage box 11. The pivot openings 28 may either be circular or shaped in the form of a keyhole for joinder of the pivot pins 27 to the openings 28. A modified form of latch may be useful in some instances. For instance the peg 18 may be located on the upper portion of the upright body 21, which may be considered a portion of the catch portion 160. The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.	A silicon wafer storage box must be secured by a functional and convenient latch during the fabrication and transportation of silicon wafers. The present invention encompasses such a functional, convenient latch adaptable for either manual or automated manipulation. The invention includes a rigid upper tab having a peg adapted for interaction with a robot arm of an automated process. The invention also includes a resiliently flexible bottom bight having a horizontally extending rigid lower tab, adapted for manual manipulation. The invention permits convenient, efficient manipulation of the latch by either a person or by an automated process.	8
BACKGROUND OF INVENTION This invention relates to a method of partitioning a particle size distribution diagram of a mixture of several kinds of granular substances having different mean particle sizes, that is, a method of drawing boundary lines between the distributions of respective substances and, especially, to such method using a technique of fuzzy inference in its process. For example, white blood corpuscles are composed of a mixture of lymph corpuscles, monocytes and granulocytes and its particle size distribution diagram prepared by measuring its particle size and corresponding frequency shows a curve, as shown in FIG. 1, having three peaks A, B and C which correspond respectively to the lymph corpuscle, monocytes and granulocytes. When the number of particles of each substance is counted from this diagram it is necessary to draw partition lines 2 and 4 between the respective peaks to define the regions of respective substances. While these partition lines may be drawn from the bottoms of valleys of the distribution curve as shown, it cannot be done so simply in practice. Because the particle size distribution curve available from a conventional device such as disclosed in U.S. Pat. No. 3,515,884 has undulations as shown in FIG. 2 due to quantizing errors at the time of A/D conversion of measured particle sizes. Such a particle size distribution diagram having undulations often provides a result falling short of an expectaton of experts, when it is input in a computer to seek a position of the minimum frequency. Accordingly, it has been a general practice to execute a smoothing process, such as calculation of a moving average of the data, before patitioning or analyzing the particle size distribution as disclosed in U.S. Pat. No. 4 817 446 for example. However, it has been impossible to completely remove the undulations by such a smoothing process and, due to such a simple definition of the partitioning position as the minimum frequency position, the above-mentioned problem has been maintained and reproducibility of the result has been very low. For example, if some undulations as shown in FIG. 3 are left in the valley of the distribution curve, the partitioning position of the computer is liable to move within a range R. Although the apparent undulations can be removed completely by enforcing the smoothing process, it is not recommended since the distribution may lose its characteristic feature. Accordingly, an object of this invention is to provide a novel and improved method which can determine the partitioning position constantly at high reproducibility, using a particle size distribution curve having undulations as described above. SUMMARY OF INVENTION The above object can be attained by applying a fuzzy inference to the partitioning process in accordance with this invention. According to the method of this invention, as schematically shown in a flow chart of FIG. 4, a one-dimensional particle size distribution diagram indicative of a relationship between the particle size and its frequency is sought first (S1) and plural points (hereinunder referred to as "estimation points") are set on its abscissa (particle size axis) to infer acceptability (hereinunder referred to as "estimated value") of each point as the partitioning position. To this end, the values of predetermined characteristic parameters are then calculated at each estimation point (S2) and a corresponding estimated value is sought in accordance with a production rule indicative of the relationship between each characteristic parameter and the estimated value (S3). Then all the estimated values at each estimation point are combined to obtain a composite estimated value (S4) and the estimation point corresponding to the maximum one of all composite estimated values is appointed to the partioning position (S5). According to a feature of this invention, the above-mentioned characteristic parameters include, at least, a below-mentioned relative frequency at the estimation point (hereinunder referred to as "first characteristic parameter"), a sum of frequencies within a small particle size interval around the estimation point inclusive (hereinunder referred to as "second characteristic parameter") and an below-mentioned quantity relating to a distance between the estimation point in problem and the estimation point corresponding to the maximum frequency (hereinunder referred to as "third characteristic parameter"). According to the above-mentioned production rules the estimated value is high if the first characteristic parameter is small, the estimated value is high if the second characteristic parameter is small and the estimated value is high if the third characteristic parameter is close to a predetermined value. According to another feature of this invention, the above characteristic parameters may further include an absolute frequency at the estimation point (hereinunder referred to as "fourth characteristic parameter"), a gradient of the distribution curve at the estimation point (herein-under referred to as "fifth characteristic parameter") and/or a difference of sum frequencies within two small particle size intervals in both sides of the estimation point (hereinunder referred to as "sixth characteristic parameter"). According to the production rules in these cases, the estimated value is high if the fourth characteristic parameter is small, the estimated value is high if the fifth characteristic parameter is small and the estimated value is high if the sixth characteristic parameter is small. According to a further feature of this invention the converses of the above production rules can be used also. These features of this invention will be described in more detail below about an embodiment thereof with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS In the drawings: FIG. 1 is a diagram showing a schema of particle size distribution of white blood corpuscles; FIG. 2 is a diagram showing a particle size distribution curve having undulations obtained by a conventional measuring device; FIG. 3 is an enlarged view of a part of a valley of the particle size distribution curve of FIG. 2 to which a smoothing process is applied; FIG. 4 is a flow chart showing a schema of the partitioning process according to the method of this invention. FIG. 5 is a block diagram showing a device used in an embodiment of the method of this invention. FIG. 6 is a diagram showing an example of the particle size distribution curve partitioned in the above embodiment; FIGS. 7a and 7b are diagrams respectively showing antecedent and conclusive membership functions of a fuzzy production rule used in the above embodiment: FIGS. 8a and 8b are diagrams respectively showing antecedent and conclusive membership functions of a converse of the above production rule also used in the same embodiment; FIGS. 9a and 9b are diagrams respectively showing the conclusive membership functions of FIGS. 7b and 8b corrected in accordance with the value of a characteristic parameter: and FIG. 9c is a diagram illustrative of a procedure of combining the diagram of FIGS. 9a and 9b to obtain a composite estimated value. DESCRIPTION OF PREFERRED EMBODIMENT In FIG. 5 a phantom block 10 containing functional elements 12, 14 16 and 18 is a basic section for applying fuzzy inference to a particle size distribution datum to determine its partition points in accordance with the method of this invention. More particularly, a characteristic parameter generator 12 receives a one-dimensional particle size distribution datum as shown in FIG. 6, for example from a particle size counting device (not shown) as described above, and derives therefrom various characteristic parameters as described below. These characteristic parameters are supplied to a fuzzy inference engine 14. The fuzzy inference engine 14 is also supplied from a partioning knowledge base 16 with below-mentioned membership functions. The fuzzy inference engine 14 applies fuzzy inference to the characteristic parameters based upon the membership functions to determine the partition points as described below. The resultant partition points are then displayed by a resultant partition display 18. The resultant partition display 18 can also display, at the same time, a folded line diagram which shows an estimated value indicative of the likelihood of each partition point. The functional elements outside the phantom block 10 of FIG. 5 serve additional functions for the above basic section 10. More particularly, a knowledge acquiring user's interface 20 serves to compare the partition point determined by the basic section 10 and displayed by the display 18 with a partition point selected by an expert in this field and to correct the membership functions and like so as to reduce the difference therebetween. A knowledge base editor 24 serves to initialize the partitioning knowledge base 16 for such knowledge bases as membership functions and production rules and also to effect correction, supplementation and cancellation thereof. The characteristic parameter generator 12 derives six characteristic parameters for example from the one-dimensional particle size distribution datum of FIG. 6. The particle size distribution diagram is drafted by selecting N values of particle size as estimation points x i (i=1,2,...N) and counting the frequency of particle size at each estimation point. In this embodiment, the number N is set to 256. Although the actual curve has many undulations as shown in FIG. 2 such undulations are not shown in FIG. 6 for convenience of explanation. While the characteristic parameters may be derived at all estimation points, it is not always needed. In other words, when a partition point is to be determined between the peaks A and B of FIG. 6, for example, it is enough to derive them at the estimation points x i between an estimation point x pl corresponding to the top of the peak A and an estimation point x p2 corresponding to the top of the peak B. The characteristic parameter generator 12 derives first the frequency f(x i ) or absolute frequency at each estimation point x i as one of the characteristic parameters. The reason for selecting the absolute frequency f(x i ) as a characteristic parameter is that its value generally becomes minimum at a point which is likely in the bottom of a valley. However, when the maximum frequencies of the peaks A and B are extremely large and the other frequencies are relatively small and not so different from each other, that is, when the valley is relatively flat and broad, the absolute frequency is lacking in reliability as a characteristic parameter. Therefore, the characteristic parameter generator 12 derives a relative frequency of an alternative characteristic parameter. Here, the relative frequency means a percentage of the frequency at each estimation point with respect to the greatest absolute frequency, that is the frequency f r (x i ) given by the following equation. f.sub.r (x.sub.i)=f(x.sub.i)×100/f.sub.p (1) While this value relates to the magnitude of absolute frequency f(x i ) with respect to the absolute frequency f p , it assumes a same value regardless of the values of f(x i ) and f p if the ratio thereof is fixed. Therefore it is undesirable to use it alone as a condition of estimation and it is recommendable to use it with the absolute frequency. The characteristic parameter generator 12 further derives a sum of frequencies at 2n+l estimation points around the estimation point x i inclusive as a characteristic parameter. This value f s (x i ) is given by the following equation. ##EQU1## where n is an integer selected experientially. It can be said on this characteristic parameter that the smaller the value thereof, the nearer the bottom of the valley the estimation point x i is, even if the particle size distribution has undulations. The characteristic parameter generator 12 also derives a mean gradient of the particle size distribution curve within a small interval including the estimation point x i as a charactertistic parameter. This value f g (x i ) is given by the following equation. ##EQU2## where m is an integer selected experientially. This value can be used as a characteristic parameter since the smaller it is, the more likely it is the bottom of the valley. The characteristic parameter generator 12 may derive also a certain value relating to the distance between the estimated point x i and the above-mentioned peak point x pl as a characteristic parameter This value f w (x i ) is given by the following equation, for example. ##EQU3## where W is a width of the peak of particle size distribution at its half height f p /2 as shown in FIG. 6. It has been known experientially that the nearer this value draws to a specific value, the nearer the estimation point x i draws to the bottom of valley. The characteristic parameter generator 12 may further derive a difference between two sums of frequencies within two small intervals on both sides of the estimation point x i as a characteristic parameter. This value f d (x i ) is given by the following equation. ##EQU4## where k is an integer selected experientiatly. This characteristic parameter is effective to locate the partition point in the middle of two peaks in such a case where the valley therebetween is relatively flat and linear. Fuzzy production rules indicative of the relationships of these characteristic parameters and the aforementioned estimated value and antecedent and conclusive membership functions of the respective production rules are determined by those skilled in this field and previously fed from the knowledge data base editor 24 into the partitioning knowledge base 16 and stored therein. The fuzzy inference engine 14 reads these membership functions in accordance with the characteristic parameter values supplied from the characteristic parameter generator 12 and executes a fuzzy inference operation as described below. For example, in the case of using the aforementioned absolute frequency as a characteristic parameter, such a proposition as "If the absolute frequency is small, the estimated value is high." is obtained as a production rule. In this case, the antecedent membership function reading "the absolute frequency is small" is given experientially as shown in FIG. 7a and the conclusive membership function reading "the estimated value is high" is given experientially as shown in FIG. 7b. Supposing now the absolute frequency from the characteristic parameter generator 12 is 15 for example, it is found from the antecedent membership function of FIG. 7a that its degree of matching is 0.13. Then, the "head" of the conclusive membership function of FIG. 7b is cut off at the level of 0.13 of the degree of matching to obtain a corrected pattern 3C FIG. 9n. Such conclusion discounting method by "head-cutting" is well known in the art and will not be described in further detail. Next, for considering about inconsistent production rules at the same time, similar inference is made in accordance with a production rule reading "If the absolute frequency is large, the estimated value is low" which is the converse proposition of the above-mentioned production rule. In this case, an antecedent membership function reading "the absolute value is large" of FIG. 8a and a conclusive membership function reading "the estimated value is low" of FIG. 8b are used. As the degree of matching corresponding to the absolute frequency of 15 is now 0.25 as shown in FIG. 8a the "head-cutting" of the conclusive membership function is effected at this level as shown in FIG. 8b and a corrected pattern 32 of FIG. 9b is obtained. Both corrected conclusive membership functions 30 and 32 obtained as above are then combined into a logical sum to result in a pattern 34 as shown in FIG. 9c, which represents the composite estimated value. While there are several methods for defuzziying this pattern into a single composite estimated value, the center of gravity G of the pattern 34 is sought in this embodiment and the abscissa E(x i ) of the center of gravity is appointed to the composite estimated value of the estimation point x i . Such defuzzification using this center of gravity method is also well known in the field of fuzzy inference and, therefore, no further detailed description will be made here. Such composite estimated value is sought in the same fashion at each estimation point and the estimation point corresponding to the greatest one of them is appointed to the objective partition point. While, in the above embodiment the logic sum of the two resultant corrected membership functions has been sought with the production rule relating to a specific characteristic parameter, namely, the absolute frequency and with its converse proposition, some of the other characteristic parameters as above mentioned may be used at the same time. The production rules for these characteristic parameters are determined as follows, for example. "If the relative frequency f r (x i ) is small the estimated value is high.", "If the relative frequency f r (x i ) is large, the estimated value is low.", "If the sum of frequencies within the adjoining small interval f s (x i ) is small the estimated value is high.", "If the sum of frequencies within within the adjoining small interval f s (x i ) is large, the estimated value is low.", "If the gradient of the adjoining small interval f g (x i ) is small the estimated value is high.", "If the gradient of the adjoining small interval f g (x i ) is large, the estimated value is low.", "If the departure from the peak f w (x i ) is close to a predetermined value, the estimated value is high.", "If the departure from the peak f w (x i ) is not close to a predetermined value, the estimated value is low.", "If the difference between two sums of frequencies within two small intervals on both sides f d (x i ) is small, the estimated value is high." and "If the difference between two sums of frequencies within two small intervals on both sides f d (x i ) is large, the estimated value is low.". When two or more characteristic parameters are used, the conclusive membership functions based upon the respective production rules are "head cut" with the orders of matching of the respective characteristic parameters according to the respective antecedent membership functions to obtain four or more corrected patterns and a logic sum of the resultant patterns is sought to prepare a composite estimated pattern It is not always necessary to use all of the above-mentioned six characteristic parameters and it is enough to use three of them that is f r (x i ), f s (x.sub.) and f w (x i ). While a logic sum of the corrected conclusive membership functions is used in the above embodiment an algebraic sum may be used also. While the conclusive membership function is corrected by "head cutting" in accordance with the degree of matching of the characteristic parameter value, any correcting method well known in the fuzzy inference technique may be used also. While the center-of-gravity method is used for defuzzification of the composite estimated value, any known method such as median method may be used also. In contrast to the prior art method using crisp inference which appoints for example a minimum frequency point to the partition point, the particle size distribution partitioning method of this invention using fuzzy inference can provide a result which is less affected by the undulations of the distribution curve and very close to an expert's conclusion, since the inference is executed in consideration of plural characteristic parameters.	A method of using a technique of fuzzy inference for partioning a particle size distribution diagram indicative of a relationship between particle size and its frequency of a mixture of several kinds of granular substances, such as white blood corpuscles including lymph corpuscles, monocytes and granulocytes, to define particle size regions for the respective substances. More particularly, some estimation points are selected on the abscissa of the particle size distribution diagram and some characteristic parameters are calculated at each estimation point with the corresponding frequency. A fuzzy production rule for each characteristic parameter is applied to seek an estimated value of the estimation point and the estimated values for all characteristic parameters at each estimation point are combined to obtain a composite estimated value. The estimation point corresponding to the greatest one of all resultant composite estimated values is appointed to an objective partition point.	6
[0001] This invention was made with Government support under contract No. DE-AC04-94AL8500 awarded by the U.S. Department of Energy. The Government has certain rights in the invention. FIELD AND HISTORICAL BACKGROUND OF THE INVENTION [0002] The present invention is directed to a support structure, and more particularly to a fiber-reinforced support structure for use in precision manufacturing. The support structure is a composition that can be tailored to match manufacturing requirements for coefficients of thermal expansion, stiffness and dampening. [0003] Demands for high precision in manufacturing systems has placed increased performance demands upon subsystems, such as supporting structure, control computers, and laser interferometers. The range of applications for computers and lasers far exceeds that of precision support structures. As such, large companies with a vast engineering infrastructure tend to be the producers of high sales volume products, such as computers and lasers. Conversely, small companies tend to be the producers of precision support structures, which have a limited demand. These small companies tend to have small engineering staffs and limited analysis capabilities. As a consequence, technological advances in support structures have lagged behind the laser and computer industries. Accordingly, the support structure has become the critical, performance-limiting component in many precision manufacturing systems. [0004] Recently, the requirements for increased stability has risen in applications such as the high-speed manufacturing of very large flat panel displays, as well as the manufacture of next generation integrated circuits with feature sizes less than 0.1 micron. As a result, better structure materials are required for the supporting structures to meet the future technological needs of the precision product industry, such as the semiconductor industry. [0005] Structure materials for the mechanical stages used to support silicon wafer during processing are one example where improvement is needed. Semiconductor processing stages must be lightweight (to enhance rapid throughput), have good stiffness (to allow precision processing, such as for photolithography) and have a coefficient of thermal expansion that matches with silicon (so no thermally imposed distortions influence the precision processing). [0006] Currently, aluminum and aluminum alloys are the most commonly used stage material. However, aluminum is too dense (and therefore too heavy), lacks the required stiffness when mass is minimized, and has thermal expansion properties far greater than that of silicon. [0007] It is extremely desirable for precision stage devices, such as magnetically levitated photolithography machines, to possess a capability of high translation rates while maintaining a very high level of accuracy. For optimal performance, the stage components should have low weight for fast translation with minimal energy, high damping capacity to reduce the time for positional stability after translation (which is dependent on vibration dampening of the component), and higher resistance to non-steady-state distortion arising from any thermal inputs. [0008] Various fiber-reinforced support structures are known and have been used in other industries. Representative examples include the following U.S. patents: U.S. Pat. No. 4,680,216 to Jacaruso; U.S. Pat. No. 4,833,029 to DuPont et al.; and U.S. Pat. No. 6,051,302 to Moore. In each of the above examples fiber fabric is used to reinforce a honeycomb core structure. [0009] U.S. Pat. No. 4 , 680 , 216 to Jacaruso teaches a single-layer fiber fabric reinforcement of a honeycomb core panel. In the preferred embodiment, the single-layer fabric is composed of graphite fibers woven at a ±90° angle to each other. [0010] U.S. Pat. No. 4,8337029 to DuPont et al. teaches a reinforced honeycomb facesheet where the reinforcement consists of a layer of graphite paper and a layer of loosely interwoven graphite fiber cloth on both the top and bottom surfaces of the facesheet. [0011] U.S. Pat. No. 6,051,302 to Moore teaches thermally conductive, nonmetal carbon pitch honeycomb panel reinforced by one layer of perforated carbon fiber fabric on the top surface of the panel and a one layer of nonperforated carbon fiber fabric on the bottom surface. [0012] In view of the above, there remains a need in the precision manufacturing industry for a support structure material with a low coefficient of thermal expansion, sufficient stiffness to reduce vibration, and of minimal weight. There additionally remains a need for a support structure material that can be specifically tailored to (1) reduce manufacturing processing times by decreasing stage translation times as well as the wait time for damping of structural resonances, and (2) reduce manufacture processing errors caused by thermal distortions. OBJECTS AND SUMMARY OF THE INVENTION [0013] The principal object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing which overcomes the drawbacks associated with conventional support structures. [0014] An object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing which is made of a fiber-reinforced composite material comprised of a laminate of carbon-fiber reinforced epoxy skins covering an aramid fiber honeycomb structure. [0015] Another object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing which results in a weight reduction of more than 50%, compared to the conventionally used support structure materials, such as aluminum and aluminum alloys. [0016] Yet another object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing wherein the composite structure can be tailored to reduce the coefficient of thermal expansion to near zero compared with the expansion of 25 ppm for aluminum (silicon is 6 ppm). [0017] Still yet another object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing wherein the stiffness of the support structure is anisotropic, but can be tailored so that it exceeds that of aluminum in the direction where strength is needed, i.e., in the x-y plane of the support structure. [0018] An additional object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing which will maintain dimensional stability and lower mode harmonics, thereby allowing for quicker damping of vibrations after stage translation. [0019] Yet an additional object of the present invention is to provide a fiber-reinforced support structure for use in precision manufacturing which is easy to machine and inexpensive to produce. [0020] In accordance with the present invention, a fiber-reinforced support structure for use in precision manufacturing includes a composite housing having a core sandwiched between first and second groups of carbon-fiber reinforced layers. A plurality of cavities in the housing are provided for removably receiving inserts utilized to support components during precision manufacturing. Each of the cavities is lined with a carbon-fiber reinforced layer, and a protective ultraviolet-cured coating is provided on the exterior of the housing to prevent contamination in the manufacturing environment. BRIEF DESCRIPTION OF THE DRAWINGS [0021] The above and other objects, novel features and advantages of the present invention will become apparent from the following detailed description of the invention illustrated in the accompanying drawings, in which: [0022] [0022]FIG. 1 is a top perspective view of a fiber-reinforced support structure made in accordance with the present invention. [0023] [0023]FIG. 2 is a bottom perspective view of FIG. 1. [0024] [0024]FIG. 3 is a cross-sectional view taken along line 3 - 3 of FIG. 1; and [0025] [0025]FIG. 4 is a schematic illustration of the sequence in which the fiber-reinforced layers are provided on a core. DETAILED DESCRIPTION OF THE INVENTION [0026] The support structure in the form of a composite C is fabricated by using a film epoxy adhesive to bond preferably 20 and 30 mil graphite/epoxy skins onto a core. As shown in FIG. 3, a preferably 1.25 inch aramid honeycomb core 10 is provided. A plurality of graphite-epoxy unidirectional layers are then attached to the top and bottom surfaces 12 and 14 , respectively, by using an adhesive. [0027] In particular, in one embodiment, a first graphite-epoxy layer 16 is attached such that the fibers therein are oriented at 0° (shown by line 17 in FIG. 4). A second graphite-epoxy unidirectional layer 18 is then placed over the layer 16 , in a manner that the fibers therein are oriented 90° to the fibers in the layer 16 (see line 19 in FIG. 4). A third graphite-epoxy unidirectional layer 20 is then placed over the layer 18 , in a manner that the fibers therein are oriented 45° from the orientation of fibers in the layer 18 (see line 21 in FIG. 4). A fourth layer of the graphite-epoxy unidirectional layer 22 is then placed over the layer 20 , in a manner that the fibers therein are oriented generally parallel to the fibers in the first layer 12 (see line 17 in FIG. 4). A fifth layer of the graphite-epoxy unidirectional layer 24 is then placed over the layer 22 , in a manner that the fibers therein are oriented 45° from the fibers in the layer 22 (see line 23 in FIG. 4). Finally, the last graphite-epoxy unidirectional layer 26 is placed over the layer 24 , in a manner that the fibers therein are oriented 45° from the fibers in the layer 24 (see line 19 in FIG. 4). In the same manner, the bottom surface 14 is provided with, preferably six graphite-epoxy unidirectional layers to complete the basic composite structure. The graphite-epoxy layers are attached to the honeycomb core 10 using the structural adhesive film and compression. [0028] As shown in FIGS. 1 and 3, cavities 28 are then machined in the composite structure C. Preferably, cavities 28 are lined with graphite-epoxy composite layers to provide a smooth bonding surface. Although not shown, the cavities 28 may be provided with screw-threads that correspond with the screw-threads in inserts 30 . It is thus seen that this composite structure C allows for easy incorporation of control features through rapid machining. [0029] It is noted herewith that although square and octagonal cavities are shown, it is within the scope of this invention to provide cavities of different shapes and configurations, as desired. It is further noted herewith that although six layers of graphite-epoxy layers have been shown to be provided on each of the upper and lower surfaces 12 and 14 of the core 10 , it is within the scope of this invention to provide more or less layers, as desired to meet specific manufacturing applications and conditions. In addition, it is noted that the orientation of the fibers in various graphite-epoxy layers is varied by an angle between 0-90°, preferably 45°. Although not shown, the graphite-epoxy layers are also bonded to the sides of the core 10 , to increase stiffness of the support structure and cover the exposed honeycomb surfaces. Finally, the composite C is sealed with a UV-cured epoxy to prevent any debris or other contamination in the manufacturing environment. [0030] As described above in the preferred embodiment, the in-plane orientation of the composite support structure C of the invention has the minimum thermal expansion coefficient of about zero with a maximized stiffness (in the same orientation) of 1.24×10 5 MPa, almost double to that of aluminum. The density of the composite support structure C is approximately 0.55 g/cc, which is five times smaller than that of aluminum. Table 1 compares the properties of an aluminum support structure with the composite support or structure C of the present invention. TABLE 1 Aluminum Composite of the Property (prior art) Invention % Improvement CTE (ppm) 25 ˜0 ˜100% Stiffness (Mpa) 7 × 10 4 1.24 × 10 5 77% Density (g/cc) 2.69 0.55 87% Overall weight (lbs) 7.7 3.8 51% [0031] While all the above properties are tailorable for the current invention, for the example of the preferred embodiment it can be seen that the support structure of the present invention has significantly improved stiffness, lower density, and is about one-half in weight to that of an identical support made of aluminum. [0032] The coefficient of thermal expansion of the composite support structure C of the present invention is preferably variable (depending upon the laminate structure chosen) and can be tailored from near zero ppm to almost any desired goal. Therefore, an exact match can be made for the semiconductor or any other precision material that is being processed. [0033] In lithography for example, the 51% reduction in support structure weight allows for a corresponding improvement in processing speeds. Likewise, the improved thermal stability allows for more overlay exposures and the higher internal damping allows for quicker vibrations settling before wafer exposure. [0034] One of the principal applications of this improved support structure is as a magnetically levitated stage for use in photolithographic semiconductor wafer processing. Directly related applications involve other stages to process semi-conductor materials where precise positioning, thermal stability, stiffness and low weight throughput are critical. Other applications for the fiber-reinforced composite support structure C of the present invention include any vendors that supply photolithography equipment to the semiconductor manufacturers. This includes steppers, magnetically levitated stages or as a vacuum wafer chuck. [0035] While this invention has been described as having preferred ranges, steps, materials, or designs, it is understood that it is capable of and designed for further modifications, uses and/or adaptations of the invention following in general the principle of the invention, and includes such departures from the present disclosure, as those come within the known or customary practice in the art to which the invention pertains and as may be applied to the central features set forth above, and fall within the scope of the invention and of the appended claims.	A fiber-reinforced support structure for use in precision manufacturing includes a composite housing having a core sandwiched between first and second groups of carbon-fiber reinforced layers. A plurality of cavities in the housing are provided for removably receiving inserts utilized to support components during precision manufacturing. Each of the cavities is lined with a carbon-fiber reinforced layer, and a protective ultraviolet-cured coating is provided on the exterior of the housing to prevent contamination in the manufacturing environment.	8
BACKGROUND OF THE INVENTION [0001] This invention relates to controlling flow of gas in a compressed gas system, and more particularly to a check valve for use in the delivery of air under pressure from an air compressor to a storage tank holding the air under pressure. [0002] Check valves are in widespread use for permitting pressurized gas to flow through a passage in one direction and preventing flow in the reverse direction. Most check valves have a movable poppet which is urged by a spring to engage a valve seat, thereby closing the valve. When force on the poppet due to air pressure exceeds the force of the spring, the poppet moves away from the seat, thereby opening the valve. [0003] One application is at a fitting on the storage tank, where a check valve receives a flow of air from a compressor for delivery to the tank, and then retains air in the tank when the compressor shuts off. That valve is exposed to a severe environment typical for a compressor discharge, including large air pressure fluctuations and turbulent flow. Consequently, the poppet and other parts of the valve are subject to substantial vibrations which can result in noise, damage, and/or failure. Some valves of the prior art include a guide mounted inside the valve for guiding movement of the poppet to prevent damage. Unfortunately, these guides are frequently located at a position within the valve where installation and replacement of a guide is difficult, or they are flexible in construction or otherwise ill-suited for the severe environment. Moreover, some guides or springs have configurations which obstruct a significant portion of the available flow area of the passage, thereby degrading air pressure as it flows through the valve and potentially causing additional vibration or failure. BRIEF SUMMARY OF THE INVENTION [0004] Among the several objects of one or more embodiments of the invention may be noted the provision of a check valve which is adapted to reliably check escape of compressed air in association with a compressed air tank and air compressor which supplies the tank with compressed air; the provision of such a valve which can withstand the severe compressor discharge environment; the provision of such a valve which is easily assembled; the provision of such a valve which avoids substantial decrease in pressure of the air as it flows through the valve; the provision of such a valve which, in one embodiment, is adapted for relief of air pressure therein when the compressor shuts down; and the provision of such a valve which is of economical construction. [0005] In general, a check valve of the present invention comprises an elongate body having a passage extending therethrough from a first end constituting its end for entry of gas under pressure to flow through to a second end constituting its end for exit of the gas. The passage is formed with a valve seat intermediate its ends spaced from and directed toward the exit end. A retainer is fixed in the passage spaced downstream from the seat apertured for the exit of the gas. The retainer has a rigid construction with a substantially central sleeve extending therefrom toward the seat. A poppet is slidable in the sleeve biased for engagement with the seat for blocking flow through the passage and disengagement from the seat on pressurization above a predetermined value for flow in the space around the sleeve and through the retainer for exit from the passage. [0006] In another aspect, a check valve of the present invention is for a compressed gas system. The valve comprises a valve body adapted for connection to the compressed gas system, the body having opposite ends and an internal passage extending through the body between an entry at a first end of the body and an exit at a second end of the body. A valve seat is positioned between the entry and the exit. A poppet is movable between a closed position in which the poppet engages the seat to block flow of gas through the passage and an open position in which the poppet is spaced from the seat to permit flow of gas. A retainer is for mounting the poppet in the passage and for guiding movement of the poppet between the closed and open positions. A biasing member is for urging the poppet to the closed position such that the poppet is responsive to pressure of the gas exceeding a predetermined value to move the poppet away from the seat against the urging of the biasing member and to the open position. The valve body has an internal shoulder in the passage adjacent the exit end, the retainer being seated on the internal shoulder and held in place by the exit end of the body being crimped over on the retainer. [0007] Other objects and features will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS [0008] [0008]FIG. 1 is a perspective of a check valve of this invention; [0009] [0009]FIG. 2 is a top end view of the check valve of FIG. 1 with certain parts removed to illustrate a valve body; [0010] [0010]FIG. 3 is a view generally in section on line 3 - 3 of FIG. 2 and showing the valve at a closed position; [0011] [0011]FIG. 4 is a view similar to FIG. 3 showing the valve at an open position; [0012] [0012]FIG. 5 is a perspective of a poppet of the check valve; [0013] [0013]FIG. 6 is an elevation of the poppet of FIG. 5; [0014] [0014]FIG. 7 is a bottom end view of the poppet of FIG. 6; [0015] [0015]FIG. 8 is a perspective of a retainer of the check valve; [0016] [0016]FIG. 9 is a top end view of the retainer of FIG. 8; [0017] [0017]FIG. 10 is a section in the plane of line 10 - 10 in FIG. 9; and [0018] [0018]FIG. 11 is a view similar to FIG. 3 showing a modified check valve having a threaded lateral port for relieving air pressure in the valve. [0019] Corresponding reference characters indicate corresponding parts throughout the views of the drawings. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0020] Referring now to the drawings and in particular to FIGS. 1 - 4 , a check valve of this invention, designated 10 in its entirety, is shown to comprise an elongate body 12 , a movable poppet 14 , a valve retainer 16 , and a spring 18 . [0021] The valve body 12 has upper and lower cylindric ends 20 and 22 which are externally threaded for connecting the valve 10 a compressed gas system, such as to a storage tank 24 . An intermediate polygonal section 26 is suitable for engagement by a wrench. In one embodiment, section 26 is hexagonal in shape with a nominal size of 0.875 inches across external flats, but it will be understood that the section can have other shapes and sizes. The elongate body 12 (formed of brass, for example) has a passage 28 extending therethrough from a first end 30 constituting its end for entry of gas (air) under pressure to flow through to a second end 32 , constituting its end for exit of the gas. Passage 28 is formed with a tapered valve seat 34 intermediate its ends, more particularly at the upper end of the intermediate section 26 (the upper end of an intermediate section 36 of the passage 28 ), the seat being spaced from and directed toward the exit end 32 . The body 12 has an internal shoulder 38 in the passage 28 adjacent the exit end 32 . Other forms of the valve body 12 , including configurations assembled from two or more parts, other sizes, and valve seat arrangements do not depart from the scope of the invention. The body 12 is shown in FIG. 2 with the poppet 14 , retainer 16 , and spring 18 removed for illustration. [0022] The poppet 14 is movable between a closed position (FIG. 3) in which the poppet engages the seat 34 to block flow of gas through the passage 28 and an open position (FIG. 4) in which the poppet is spaced from the seat to permit flow of gas through the valve 10 . The poppet 14 is slidable in the retainer 16 and biased by the spring 18 to the closed position. When air supplied to the entry end 30 has a pressure above a predetermined value such that a force applied to the poppet 14 by the air exceeds an opposing force applied by the spring 18 , the poppet disengages from the seat 34 and moves to the open position. [0023] The poppet 14 (FIGS. 5 - 7 ) comprises a generally cylindric stem 40 configured for being slidably received in the retainer 16 and a head 42 for sealing engagement with the seat 34 . The head 42 comprises, in one embodiment, a toroid shaped seal which is mounted on the stem 40 . The stem 40 has two spaced flanges 44 thereon, with the head 42 being captured between the two flanges 44 . The head 42 is mounted on the stem 40 with an interference fit to ensure it is tight and reliably secured. In the preferred embodiment, the head 42 has a nominal inside diameter of about 0.177 in., and the stem 40 has a diameter of about 0.193 in. Thus the head 42 must stretch to be inserted on the stem 40 , and it remains tightly in position when exposed to turbulent flow of air. Other types of connections or fits between the head and stem, or one integral part, do not depart from the scope of this invention. [0024] The stem 40 is formed of a suitable material which is strong, rigid, thermally stable, and resistant to corrosion and wear. In the preferred embodiment, the stem 40 is formed of a thermoplastic resin such as RYTON thermoplastic (RYTON is a federally registered trademark of the Chevron Phillips Chemical Company LP of Houston, Tex.). The head 42 is sized for mounting on the stem 40 and configured to sealingly engage the seat 34 . It is formed of a suitable material which is resilient, strong, thermally stable, and resistant to corrosion and wear. In the preferred embodiment, the head 42 is formed of a synthetic rubber such as VITON fluoroelastomer (VITON is a federally registered trademark of DuPont Dow Elastomers L.L.C. of Wilmington, Del.). Other shapes and materials may be used for the stem and head without departing from the scope of this invention. [0025] The valve retainer 16 (FIGS. 8 - 10 ) mounts the poppet 14 in the passage 28 and guides movement of the poppet between its closed and open positions, preventing any change to the orientation of the poppet which could result in failure of the valve 10 . The retainer 16 comprises a substantially central sleeve 46 and an annular outer rim 48 spaced from the sleeve and sized to engage the valve body 12 . The sleeve 46 , which extends from the retainer 16 toward the seat 34 (FIG. 3), receives the poppet 14 and defines a linear path of movement between the closed and open positions. The sleeve 46 is mounted in alignment with the body 12 (i.e., coaxial with the passage 28 ) such that the path of movement of the poppet 14 is aligned with the body and generally along its center. [0026] In order to ensure good alignment, a radial clearance between the stem 40 and an inner surface of the sleeve 46 is small. In the preferred embodiment, the clearance is in a range of 0.006 to 0.014 in., and more preferably about 0.010 in. (i.e., the stem 40 has an outer diameter of about 0.195 in. and the sleeve 46 has an inner diameter of about 0.205 in.). Further for maintaining alignment, the sleeve 46 preferably has an axial length L (FIG. 10) extending a distance greater than the outer diameter of the stem 40 (1.8 times in the preferred embodiment), and also preferably extending at least the distance traveled by the poppet 14 in moving between open and closed positions. In the preferred embodiment, the sleeve 46 has a length L (FIG. 10) of about 0.350 in.; the poppet 14 has a total length L2 (FIG. 6) of about 0.815 in.; the portion of the stem 40 downstream of the shoulder 40 slidable in the sleeve 46 has a length L3 of about 0.570 in.; and the distance traveled by the poppet 14 in moving between open and closed positions is about 0.125 in. Other dimensions and dimension ratios do not depart from the scope of this invention. [0027] In the embodiment shown in FIG. 9, three circumferentially spaced arms 50 extend generally radially between the rim 48 and the sleeve 46 for supporting the sleeve in the passage 28 . The arms 50 define three arcuate apertures 52 in the retainer 16 between the rim 48 and the sleeve 46 , the apertures permitting exit of the flow of gas therethrough. The apertures 52 are on a circle centered in the retainer 16 , the apertures being spaced at 120 degrees around the circle. The arms 50 provide adequate support to the sleeve 46 while minimizing blockage of the flow area through the apertures 52 . [0028] The retainer 16 is formed of a suitable material which is strong, rigid, thermally stable, and resistant to corrosion and wear, such as RYTON thermoplastic. Unlike some prior art poppet guides which are flexible, the rigid retainer 16 makes it particularly effective for use in a compressor discharge environment. Preferably, the sleeve 46 , outer rim 48 , and arms 50 are integrally formed, although it is understood that a retainer formed of several separate parts does not depart from the scope of this invention. Further, the number, size, and configuration of the arms and apertures may vary so long as the sleeve is rigidly supported and the gas is able to flow freely through the retainer. [0029] As seen in FIG. 3, the retainer 16 is fixed in the passage 28 , spaced downstream from the valve seat 34 . The outer rim 48 is seated on the internal shoulder 38 in the passage at the exit end 32 of the passage and body and held in place by the exit end being crimped over on the retainer 16 . Significantly, the position of the retainer 16 at the exit end 32 beneficially provides for straightforward assembly, good accessibility, and avoids the difficulty of trying to maneuver the retainer for attachment at a location deep inside the passage 28 . Crimping provides a simple attachment and precludes fasteners or more complex retainers which are integral with the body. However, it is understood that the attachment can be done in other ways without departing from the scope of this invention. [0030] The spring 18 (FIG. 3) comprises a helical compression spring extending between the retainer 16 and one of the flanges 44 on the poppet 14 . That flange 44 has a raised shoulder 54 engageable by the spring 18 for seating the spring and preventing lateral shifting of the spring. Therefore, the spring 18 is guided and constrained from lateral shifting on both of its ends (i.e, by both the retainer 16 and the poppet 14 ) so that it will remain secure as the poppet moves and when exposed to turbulent flow of air. Springs 18 of varying spring constant may be selected appropriate to the expected air pressure and/or size of the valve 10 to select the predetermined value of air pressure which moves the poppet 14 from the closed to the open position. In the preferred embodiment, the spring 18 is formed of stainless steel. It is understood that other types of springs or biasing members and other materials do not depart from the scope of this invention. [0031] Significantly, the spring 18 is configured to remain out of the path of air as it flows through the passage 28 to prevent flow turbulence, loss of air pressure, and vibratory motion of the spring. The spring 18 has turns of uniform diameter which are configured to remain generally adjacent to the retainer 16 and the poppet 14 along an entire length of the spring, such that when the poppet is at the open position, flow of air through the passage 28 is not obstructed by any part of the spring. A radial clearance between the spring 18 and sleeve 46 (and between the spring and the shoulder 54 ) is within a range of about 0.003 to 0.031 in., and more preferably about 0.017 in. In the preferred embodiment, the sleeve has an outside diameter of about 0.300 in. and the spring 18 has an inside diameter of about 0.317 in. Other dimensions and dimension ratios do not depart from the scope of this invention. [0032] The passage 28 and the poppet 14 are sized for providing adequate flow areas as air passes through the valve 10 to avoid causing a decrease in either pressure or mass flow. The intermediate section 36 defines a minimum area, or “throat” of the valve 10 . When the poppet 14 is open, the flow area in the passage 28 increases as the air moves from the intermediate section 36 past the conical seat 34 . Preferably, the flow area downstream of the conical seat is in a range from about 125% to 225% of the flow area at the intermediate section 36 , and more preferably about 175%. In the preferred embodiment, for example, the intermediate section 36 has a flow diameter of about 0.312 in., providing a cross sectional flow area of 0.076 square in. Downstream of the conical valve seat 34 , the cross sectional flow area of passage 28 at location 58 (see FIG. 4) is annular in shape and is about 0.132 square in. (174% of the minimum flow area). [0033] Referring to FIG. 11, a modification 60 of the check valve has a conventional lateral outlet 62 from the passage 28 between the entry end 30 of the body and the valve seat 34 for relieving pressure from the passage upstream from the valve seat. As known to those skilled in the art, the outlet 62 is commonly used as a threaded “unloader port” for connection of an electrical pressure switch, for example, operable to release air trapped between the compressor and the valve, subsequent to the compressor shutting off, in order to facilitate proper re-start of the compressor. [0034] The valve 10 of the present invention is compact in size and has a small number of component parts to minimize cost. The valve is reliable in operation in the severe environment typical for a compressor discharge. At the open position, the valve provides good internal flow characteristics with generally restriction-free flow areas, minimal turning (i.e., the flow proceeds generally straight through the valve) and with the only obstructions being the three arms 50 . Therefore, the valve avoids producing a substantial decrease in pressure as air flows through the valve. Assembly of the valve 10 is facilitated by the convenient position of the retainer 16 at the exit end 32 and its attachment by crimping the end. [0035] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results obtained. [0036] When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. [0037] As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.	A check valve for a compressed gas system. The valve has a body with an internal passage extending through the body and a valve seat positioned in the passage. A poppet is movable between a closed position in which the poppet engages the seat to block flow of gas through the passage and an open position in which the poppet is spaced from the seat to permit flow of gas. A retainer mounts the poppet in the passage and guides movement of the poppet. A spring urges the poppet to the closed position such that the poppet is responsive to pressure of the gas exceeding a predetermined value to move the poppet away from the seat against the urging of the biasing member and to the open position.	8
CROSS REFERENCE TO RELATED APPLICATION This application claims priority of International application number PCT/DE99/03662 filed Nov. 12, 1999, which in turn claims priority to German patent application number 198 54 038.8, filed Nov. 13, 1998. FIELD OF THE INVENTION The invention relates to a device for detecting the adjustment of translationally moved adjusting devices in vehicles. More specifically, the invention relates to detecting forces of acceleration which act on the vehicle when driving over poor stretches of road. BACKGROUND OF THE INVENTION A process is known from DE 40 20 351 C2 for electronically monitoring and controlling the opening and closing of electrically operated assemblies wherein a setting member is connected to a sensor device which detects adjusting parameters originally linked with the adjusting movement of the setting member. This device is, for example, a sensor which indicates the degree of adjusting movement of a window pane. An additional sensor is installed in the vehicle in order to determine the forces of acceleration acting on the bodywork which were not originally linked with the adjusting movement of the setting member but which are required for triggering an anti-jam protection system to safeguard people and objects from becoming jammed between the window pane and door frame of a vehicle. The drawback with this solution is that a second separate sensor element with corresponding supply leads and connectors is provided which increases the assembly and material costs. From DE 196 19 932 A1, an electric motor servo drive is known which recognizes passing through potholes without any additional sensor. In this system, the duration of a revolution of the drive axle changes suddenly and non-uniformly resulting in the triggering of an anti-jam protection device. The drawback with this solution is that the only forces of acceleration which are detected are those which exist in the adjusting direction. Furthermore, if the adjusting device is not moved, then no information on the forces of acceleration can be obtained. Furthermore, acceleration switches are known which produce a contact with the occurrence of high accelerations, e.g., in an accident. With these switches, however, no statement on the degree of acceleration is possible since it is only determined that a boundary value is exceeded. SUMMARY OF THE INVENTION The object of the present invention is to provide an apparatus, with a small structural expense, which obtains as much information as possible on the adjusting movement of translationally movable adjusting devices and the forces acting on the vehicle. According to the invention, vehicle acceleration information can be obtained without having to provide an additional sensor device. Thus, structural elements which are already present can be utilized to optimum effect. As a result, a sensor device which detects the rotary movement of an adjusting drive in order to slow down or switch off the drive upon reaching a certain position, can also detect the vibrating movement of a vehicle when driving over poor stretches of road. This information is of special importance for triggering an anti-jam protection device since the set trigger criteria can be falsified by the additional forces of acceleration. Likewise, transverse accelerations when driving fast around bends can be determined. This data can be used for fixing the boundary values of the anti-jam protection or supplied to other control devices to, for example, influence an active chassis or brake control. It is likewise possible to determine severe acceleration or deceleration of the vehicle. A further area of use of the present invention is in detecting the vibration of the adjusting drive. Driving off or starting up the engine can lead to vibration movements as a result of the breakaway forces and start-up torques which have to be overcome. With the present invention, it is possible to determine the start-up conditions which are based on external influences such as temperature or dampness. It is thus possible to, for example, standardize the threshold value for an anti-jam protection since, with stronger start-up vibrating movements, it is possible to determine a greater resistance such as a greater friction resistance of the adjusting device, so that the threshold value is correspondingly adjusted. A quantitative evaluation of the vibrating movement is likewise possible. For example, based on the extent of the vibrating movement, it becomes possible to draw conclusions relating to the resistances in the adjusting device, for example, the wrong or correct installation, wear, or optimum operating conditions. If the sensor detects the forces of acceleration acting on the vehicle in the direction of the adjusting movement, then the extra force acting on the adjusting device can be determined, and the threshold value of the anti-jam protection can be adjusted with less expense. In one embodiment of the invention, the sensor includes several sensor elements associated with each other. For example, a first sensor element is connected to the adjusting device or to a drive for the adjusting device, and a second sensor element associated with the first sensor element is mounted independently of the first sensor element. The present invention enables a determination of the forces which act on the vehicle when at least one of the sensor elements is supported resiliently directly on the vehicle chassis, or through the adjusting device or drive of the adjusting device on the vehicle chassis. If lasting or permanent displacements occur between the sensor elements, for example, following an accident, then it is possible to determine the displacement and, therefore, changed signal, about the effectiveness of the adjusting device and the degree of accident damage. For reasons of minimizing wear and optimum detection of forces additionally acting on the vehicle, it is advantageous to mount the sensor elements substantially without contacting one another. In a further development of the invention, a signal-transmitting sensor element (transmitter) sends a signal with constant amplitude and/or frequency. The amplitude and/or frequency changes detected by a signal-receiving sensor element (receiver) represent a function of the forces acting on the vehicle. Preferably, the signal-transmitting sensor element has at least one partition with two sections of different signal levels. The signal-receiving sensor element is positioned relative to the signal-transmitting sensor element so that signals emanating from the sections of different signal levels and signal changes based on the displacements of the signal-transmitting sensor element and/or signal-receiving sensor element are detected. As a result, relevant adjusting movements and the acting forces can be simply and reliably detected. In an another aspect of the invention, the circuit arrangement for evaluating the sensor signals sends an acceleration signal when the amplitude and/or frequency changes detected by the signal-receiving sensor element exceed a predetermined threshold value. The circuit arrangement for evaluating the sensor signals has an amplifier connected to the output of the signal-receiving sensor element. The output of the amplifier is connected to the input of a first comparator. The other input of the comparator is attached to a first reference voltage source which corresponds to the predetermined threshold value of the amplitude change and at whose output the acceleration signal appears. In a variation of the invention, a sensor determines the speed and/or rotary direction of the drive of the adjusting device through a signal transmitter connected to the drive shaft. A signal receiver is associated with the signal transmitter. The transmitter and receiver are mounted movable relative to each other and configured such that the signal receiver detects the relative movement between the signal transmitter and the signal receiver. The signal receiver sends sensor signals corresponding to the relative movements to the circuit arrangement. This arrangement can be achieved if the signal transmitter is supported on the drive shaft elastically displaceable in the axial direction about a rest position, and the signal receiver detects the axial displacement of the signal transmitter. Alternatively, the signal transmitter can be fixed or connected to the drive shaft, and the drive shaft is mounted elastically displaceable in the axial direction about a rest position. It is also possible, however, for the signal receiver to be mounted elastically displaceable about a rest position in the axial direction of the drive shaft and/or perpendicular to the drive shaft. In order to permit only certain movements of the signal receiver, for example, to fix the movements about a maximum deflection or to superimpose directions of movements, the signal receiver is designed displaceable along a guide path. In one embodiment, the signal transmitter is formed from a ring magnet or a cylindrical multi-pole magnet. The signal receiver is formed from a Hall sensor aligned with the ring magnet or the sleeve face of the multi-pole magnet. As an alternative embodiment, the sensor is constructed based on a magneto-resistive effect. A transmitter is formed as a cylindrical multi-pole magnet, and a receiver is formed as a magneto-resistive sensor. The receiver is aligned with the cylinder face of the multi-pole magnet. In a further embodiment, an inductive sensor is provided with a signal transmitter e.g., a cylindrical magnetic disc, which rotates between the poles of a metal fork. An induction coil mounted on the metal fork serves as a signal receiver. Through the rotation of the magnet, a voltage is induced in the induction coil which changes in dependence on the movement of the disc relative to the fork. In yet another embodiment, an opto-electronic sensor is utilized. The opto-electronic sensor includes a punctured or slit disc, a light-emitting element aligned with the end side of the punctured or slit disc, and a signal transmitter, preferably a photo-diode. In the reflection area of the rays reflected by the punctured e.g., or slit disc, a light-receiving element is provided as a signal receiver, preferably a photo-transistor. If the disc is displaced, only a part of the rays transmitted by the photo-diode is reflected. As a result, a corresponding change in the output signal of the photo-transistor is produced. If the sensor is constructed as a capacitor, a part of the sensor device includes a rotating metal disc. The metal disc includes alternating regions of different dielectric constants, and a metal plate partially covering the circular surface of the metal disc. In order for the adjusting drive or sensor device to have the greatest possible freedom with regard to the alignment of the axes of movement, a two-sided swivel lever with a vibrating mass is mounted on the lever arm remote from the signal transmitter. The lever arm is associated with the signal transmitter so that the signal transmitter is moved axially corresponding to the vibration of the mass. The lever is formed on the signal transmitter side as a fork which engages around the signal transmitter to allow displacement in both axial directions. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in further detail with reference to the following figures: FIG. 1 shows the design principle of the apparatus; FIG. 2 shows a time chart of the output signal of a sensor with sensor elements fixed independently of each other, and the output signals of the circuit arrangement according to FIG. 3; FIG. 3 shows a circuit arrangement for evaluating the sensor signals; FIG. 4 shows an arrangement with an axially movable drive shaft and a signal-transmitting sensor element fixed thereon; FIG. 5 shows a vertically mounted drive shaft with a signal-transmitting sensor element resiliently supported thereon; FIG. 6 shows a section through a ring magnet used as signal-transmitting sensor element according to FIG. 5; FIGS. 7 to 10 show different designs of a sensor device; FIG. 11 shows a sensor device with a swing lever for converting vertical movements into horizontal movements; FIG. 12 shows a of a signal-transmitting sensor element resiliently fixed on a drive shaft, and the signal-receiving sensor element fixed on the bodywork; and FIG. 13 shows a resilient arrangement of the signal-receiving sensor element, and fixing of the signal-transmitting sensor element on a drive shaft. DETAILED DESCRIPTION FIG. 1 shows a design principle of the device according to the invention for detecting the displacement of translationally moved adjusting devices 1 , for example, a window lifter drive in a vehicle door or a sunroof. The adjusting device 1 is connected to a drive device which includes an electric motor 10 , a drive shaft 11 mounted fixed on the body in shaft bearings 14 , 15 a worm 12 , and a worm wheel 13 which actuates the adjustment of the window lifter. To accurately measure the forces acting on the vehicle, there is no or only very little bearing play in the longitudinal extension of the drive shaft 11 . The drive device is assigned a sensor 2 a with a sensor element 4 a fixed on the body, and a sensor element 3 a secured against rotation to the drive shaft 11 . The sensor element 4 a is connected to a circuit arrangement for evaluating the sensor signals. This arrangement is used, for example, to detect the direction of rotation and/or the speed of the drive device and can be produced using a Hall sensor. The sensor 2 a detects the forces acting on the drive device. For this purpose, the sensor element 4 a is a locally fixed, a signal-receiving sensor element 3 a is formed as a signal-transmitting sensor element which rotates with the drive shaft 11 . The signal-transmitting sensor element 3 a is displaceable opposite the signal-receiving sensor element 4 a in the direction of the double arrow in the longitudinal direction of the drive shaft 11 which is indicated by the rotating sensor element 3 a shown off-set by dotted lines. The spring 5 a indicates that the signal-transmitting sensor element 3 a is supported resiliently against the body or against the drive device, or that the drive shaft is resiliently supported against the body. Thus, a displacement of the signal-transmitting sensor element 3 a relative to the signal-receiving sensor element 4 a will result in a change in the signal path which is dependent on the relative movement of the two sensor elements 3 a , 4 a . In this way, it is possible to detect by one sensor 2 a both the rotary movement of the drive shaft and the component of acceleration in the direction along the drive shaft. Since it is possible to decide on the magnitude of the acceleration force from the degree of displacement of the sensor element 3 a , a quantitative determination of an acceleration force acting on the drive device and the adjusting device can be performed. FIG. 2 shows the Hall voltage U H over time t received by a sensor 2 a . Signals A 1 and A 2 over time t are produced by the circuit arrangement shown in FIG. 3 . Referring to FIG. 3, a voltage regulator 81 produces a voltage and is connected to a Hall sensor 82 . The signals produced by the Hall sensor 82 are supplied to an amplifier 83 whose output is connected to the inputs of two comparators 84 , 85 . Reference voltage sources Vref 1 , Vref 2 are connected to respective comparators 84 , 85 and produce respective reference voltages U 1 and U 2 which correspond to predetermined threshold values for triggering respective signals A 1 and A 2 . If these values are exceeded or understepped, then the relevant signal A 1 or A 2 is emitted through the transistors 86 , 87 . Referring back to FIG. 2, as can be seen from the lower curve, upon reaching the reference voltage U 2 the rising flank of the signal A 2 is released. Upon reaching the greater reference voltage U 1 , the rising flank of the signal A 1 is released. The signal A 2 serves, for example, to detect the speed of the drive device, and in conjunction with an additional sensor or a circuit for detecting rotary direction, signal A 2 indicates forces acting on the adjusting device. The signal A 2 falls back to zero when the voltage U H becomes greater than −U 2 The signal A 1 ceases when the voltage U H discharged from the signal-receiving sensor element falls below a predetermined value. FIG. 4 shows an embodiment of the invention. The signal-receiving sensor element 3 b is fixed or connected to the drive shaft 11 . In order to allow the sensor elements 3 b and 4 b to move relative to each other when forces of acceleration appear, the entire drive is supported by springs 5 b . Springs 5 b are axially movable on the ends of the drive shaft 11 . Thus, the influences of the adjusting device which flow in through the worm gearing (worm 12 , worm wheel 13 ) can also be considered by the sensor 2 b. Another type of alignment of a sensor 2 c is shown in FIG. 5 . The signal-transmitting sensor element 3 c is formed as a ring magnet, and the signal-receiving sensor element 4 c is formed as a locally fixed Hall sensor. The ring magnet is mounted longitudinally and displaceable in the direction of the double arrows on the drive shaft 11 . The ring magnet is elastically mounted by a spring 5 c which is supported by and fixed to the vehicle body. In the illustrated embodiment, pretension is produced in the spring 5 c through the force of gravity so that the ring magnet is held in a rest position in the absence of forces of acceleration. The rest position is selected so that the Hall sensor 4 c is directed to the ring magnets. When driving over a poor stretch of road, the ring magnet 3 c vibrates due to the vertical forces of acceleration. The vibration is detected by the Hall sensor and forwarded as sensor signals to a circuit arrangement for evaluation. In order to ensure that the ring magnet 3 c is rotationally secured on the drive shaft 11 and simultaneously displaceable, the drive shaft 11 is provided with grooves in which a corresponding toothed area 32 of the ring magnet 31 engages, as shown in FIG. 6 . In an alternative embodiment, in FIG. 7, the signal-receiving element 4 d works on an inductive basis and the signal-transmitting element 3 d is formed as a frusto-conical magnetic disc with magnetization as shown in plan view on the lower illustration. Referring to the plan view, the signal-transmitting sensor element 3 d includes an iron core 41 formed as a metal fork. An induction coil 42 is mounted on the metal fork. During rotation of the magnetic disc, a voltage is induced in the induction coil 42 as a result of the magnetic field strength changing in the iron core 41 . The size of the voltage depends on the position of the magnetic disc in relation to the iron core 41 . As a result of the frusto-conical shape of the magnetic disc, the voltage induced in the induction coil 42 changes during upward and downward movement of the magnetic disc owing to the changing field strength in the iron core 41 . Through the incline of the sides of the frusto-conical magnetic disc positioned opposite the signal-receiving sensor element 4 d , the induced voltage is changed based on the deflection. Thus, the degree of the acceleration force can be determined. FIG. 8 illustrates sensor elements based on an opto-electronic principle. The signal-transmitting sensor element 3 e is formed as a slit disc supported elastically on the body by a spring 5 e . Light rays emitted from the signal-receiving sensor element 4 e are reflected from the circumference of the slit disc, received by the signal-receiving sensor element 4 e , and converted into electrical signals. When the slit disc moves perpendicular to the disc surface, a part of the rays is not reflected since the reflection surface changes. As a result, the acceleration force acting on the slit disc, and thus, on the adjusting device, can be determined. The signal-receiving sensor element 4 e includes a combination of a photo-diode 43 and a photo-transistor 44 . FIG. 9 shows a similar construction of the sensor element as shown in FIG. 7 . The sensor element 3 f in FIG. 9 includes a magnetic disc formed as a multi-magnet disc, and the signal-receiving sensor element 4 f includes a magneto-resistive element, e.g. a field plate. The multi magnet disc 3 f has a frusto-conical shape so that through the incline of the sides of the frusto-conical magnetic disc opposite the signal-receiving sensor element 4 f , the induced voltage is changes based on the deflection. Thus, the degree of the acceleration force can be determined. FIG. 10 shows the interaction of a signal transmitter 3 g and a signal receiver 4 g on a capacitive basis. The signal transmitter 3 g is formed as a rotating metal disc with alternating areas 33 , 34 of different dielectric constants. The metal disc is partially covered by a metal plate mounted at a distance d from the metal disc. Since the metal disc is supported axially and movable through the spring 5 g , the distance d can change in depending on the acceleration force. The capacitance is inversely proportional to the distance d. Through a radial shift of the metal plate 4 g , a change of the capacitance can be detected through the change in the covered surface A. Thus, this principle can be used to detect acceleration forces in several directions. In order to allow the drive unit to be independent to permit alignment of the drive shaft 11 , according to FIG. 11, a vibrating mass 62 is attached to an angular lever arm 6 which is movable about a rotary axis 63 . A fork 61 is coupled to the end of the lever arm 6 opposite the vibrating mass 62 . During upward and downward movement of the mass 62 , the fork 61 moves the signal-transmitting sensor element 3 h to the left and right from its rest position. Using different lever ratios, different sensitivities can be set. Similarly, through a corresponding angular position of the lever arm, any force in one direction can be detected independently of the alignment of the drive shaft 11 . Other spring elements besides spring 5 a-h can also be used. Also, a resilient support of the signal-transmitting sensor element, the signal-receiving sensor element, or both sensor elements is possible if these variations are supported, for example, on different component parts, in different directions, and/or through different spring elements. FIG. 12 shows a signal-transmitting sensor element 3 i fixed on a drive shaft 11 through a rubber-elastic spring element 5 i , which allows movement of the signal-transmitting sensor element 3 i in all directions. Thus, signal-receiving sensor element 4 i is locally mounted or fixed. As an alternative, in FIG. 13, a signal-receiving sensor element 4 j is mounted to be freely movable through spring 5 k . The sensor element 4 k is aligned in the rest position to the locally fixed rotating signal-transmitting sensor element 3 k . The signal-receiving sensor element 4 k can also be fixed through other spring elements on the body or on the drive. It is also possible that the signal-transmitting sensor element does not turn, but is encircled by the signal-receiving sensor element.	The invention relates to a device for detecting the adjustment of translationally moved adjusting devices in vehicles, especially window lifters, sunroofs and similar, comprising a sensor, which emits a sensor signal that is dependent on the adjusting movement of the adjusting device to a circuit for evaluating the sensor signal. This sensor also detects the forces of acceleration that are exerted on the vehicle and emits a signal to the circuit that corresponds to these forces of acceleration, and is characteristically modified. The sensor signals are the evaluated.	4
BACKGROUND OF THE INVENTION [0001] The present invention relates to a back-gap controlling apparatus for a compressor, and more particularly to back-gap controlling apparatus for a compressor to temporarily separate two scroll units of the compressor, thus reducing initial torque to operate the motor and limiting a displacement amount of scroll unit. [0002] The scroll compressor generally comprises two scroll units in spiral shape, wherein one scroll unit is fixed and referred to as fixed scroll, and another scroll unit has rotational movement with respect to the fixed scroll and is referred to as orbital scroll. The two scroll units are engaged each other and have 180-degree phase difference. [0003] The orbital scroll has rotation around the fixed scroll, thus forming closed space therebetween. A working fluid is shrunk, within the closed space, from peripheral to center, and then ejected out of the two scroll units. In this way, the compression stroke is provided. [0004] In above-mentioned operation, the orbital scroll is driven by a driving member. It is well known that a static friction coefficient is larger than a dynamic friction coefficient for moving a body. Therefore, a larger force is required to move the orbital scroll. The driving member requires large torque to overcome a static friction between the orbital scroll and the static scroll. The driving member has risk of damage and the lifetime of the driving member is reduced. SUMMARY OF THE INVENTION [0005] The present invention provides a back-gap controlling apparatus for compressor to prevent an excessive displacement amount of the orbital scroll and the fixed scroll of the compressor and to prevent fluid leakage. [0006] Accordingly, the present invention provides a back-gap controlling apparatus for compressor. The back-gap controlling apparatus comprises a casing comprising an accommodation space therein; an orbital scroll arranged in the accommodation space; and a fixed scroll arranged in the accommodation space and engaged with the orbital scroll. A compressed fluid pressure due to an operation between the orbital scroll and the fixed scroll will push the fixed scroll away from the orbital scroll. An abutting section to limit a displacement amount of the fixed scroll is provided between the casing and the fixed scroll. BRIEF DESCRIPTION OF DRAWING [0007] The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however may be best understood by reference to the following detailed description of the invention, which describes certain exemplary embodiments of the invention, taken in conjunction with the accompanying drawings in which: [0008] FIG. 1 shows a sectional view of the first preferred embodiment of the present invention. [0009] FIG. 2 shows the first preferred embodiment of the present invention before balance. [0010] FIG. 3 shows the first preferred embodiment of the present invention after balance. [0011] FIG. 4 shows a sectional view of the second preferred embodiment of the present invention. [0012] FIG. 5 shows a sectional view of the third preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0013] FIG. 1 shows a sectional view of the first preferred embodiment of the present invention. The present invention provides a back-gap controlling apparatus for compressor. The compressor comprises a casing 10 composed of a first shell 101 and a second shell 102 below the first shell 101 . The inner diameter of the first shell 101 is equivalent to the inner diameter of the second shell 102 to define an accommodation space for accommodating other elements in the compress. An orbital scroll 20 is placed in the casing and connected to a driving member 40 . A fixed scroll 30 is arranged in the casing 10 and engaged with the orbital scroll 20 . A floating oil seal 70 is provided atop the fixed scroll 30 . When the orbital scroll 20 and the fixed scroll 30 begin to operate, a fluid pressure generated by compression will push the fixed scroll 30 away from the orbital scroll 20 . Moreover, an abutting section 50 is provided between the orbital scroll 20 and the fixed scroll 30 to limit the displacement amount of the fixed scroll 30 , thus providing the back-gap controlling apparatus according to the present invention. In one preferred embodiment of the present invention, the abutting section 50 is a baffle plate placed within the first shell 101 and atop the fixed scroll 30 and the oil seal 70 , thus limiting the axial displacement amount of the fixed scroll 30 . [0014] FIGS. 2 and 3 show the first preferred embodiment of the present invention before and after balance, respectively. The oil seal 70 can be pushed upward when the driving member 40 is rotated. At this time, a back pressure chamber 80 is defined by the oil seal 70 and the fixed scroll 30 . Moreover, the oil seal 70 and a baffle plate screwed to the casing 10 will separate a high pressure chamber 90 and a low pressure chamber 91 . When the fixed scroll 30 is pushed away from the orbital scroll 20 , the contact area between the orbital scroll 20 and the fixed scroll 30 can be reduced. Therefore, the static friction is reduced. As already mentioned, to move a body in rest state needs larger force in comparison to move a body in moving state. Therefore, less rotational force is required to keep an already-moving body in moving status. The body will achieve rotational balance within shorter time. Because the fluid pressure will push the fixed scroll 30 away from the orbital scroll 20 , the driving member 40 will fast achieve rotational balance by less torque. [0015] Moreover, the fixed scroll 30 is pushed away from the orbital scroll 20 until the fixed scroll 30 is in contact with the baffle plate when the compressor begins to operate. This can prevent excessive displacement of the fixed scroll 30 and pressure leakage. Afterward, when the driving member 40 achieves rotational balance, the high-pressure fluid in the back pressure chamber 80 will provide force to push downward the fixed scroll 30 . Therefore, the fixed scroll 30 has downward movement until the fixed scroll 30 is again engaged with the orbital scroll 20 , as shown in FIG. 3 . In this situation, friction is still present between the orbital scroll 20 and the fixed scroll 30 . However, the friction is far smaller than the static friction accounting for rest body because the driving member 40 is in rotational balance. [0016] FIG. 4 shows a sectional view of the second preferred embodiment of the present invention. The second preferred embodiment is different to the first preferred embodiment in that the inner diameter of the first shell 101 is smaller than the inner diameter of the second shell 102 . An abutting section 50 ′ of another type is directly formed on a bottom peripheral of the first shell 101 . Therefore, the abutting section 50 ′ will limit the displacement of the fixed scroll 30 when the fixed scroll 30 is pushed away from the orbital scroll 20 . [0017] FIG. 5 shows a sectional view of the third preferred embodiment of the present invention. The third preferred embodiment is different to previous preferred embodiments in that a sealing buffer 60 is provided between the first shell 101 and the second shell 102 . The sealing buffer 60 is of annulus shape and has inner diameter the same as the inner diameter of either the first shell 101 or the second shell 102 . Moreover, the inner diameter of the sealing buffer 60 can be set between the inner diameter of either the first shell 101 and the second shell 102 . The sealing buffer 60 can buffer a contact between the fixed scroll 30 and the first shell 101 , therefore the operation noise and component abrasion can be prevented. [0018] The back-gap controlling apparatus according to the present invention has following advantages. There is higher pressure between the orbital scroll and the fixed scroll when the compressor begins to operate. The pressure will temporarily separate the orbital scroll and the fixed scroll to reduce contact area between the orbital scroll and the fixed scroll. Therefore, friction between the orbital scroll and the fixed scroll can also be advantageously reduced. The initial torque for operating the compressor can also be reduced and the driving member can fast achieve rotational balance. The lifetime of the compressor can be enhanced. The compressed fluid pressure due to operation between the orbital scroll and the fixed scroll will push the fixed scroll away from the orbital scroll and the fixed scroll has axial contact with the casing. The initial torque for operating the motor can be reduced and the liquid leakage due to excessive displacement can be prevented. The lifetime of motor can be enhanced and the excessive displacement of scroll unit can be prevented. [0019] Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.	A back-gap controlling apparatus for compressor is proposed to reduce an initial torque for the motor of a compressor. A high pressure between the two scroll units of the compressor can temporarily separate the two scroll units. The casing pro se or a sealing buffer can be used to limit a displacement amount of the scroll unit The excessive displacement of scroll unit can be prevented to enhance lifetime of motor.	5
RELATED APPLICATIONS There are currently no applications co-pending with the present application. FIELD OF THE INVENTION The present invention relates generally to a portable compartment, and in particular, to a holder for retaining dolls and doll accessories. BACKGROUND OF THE INVENTION Keeping children's toys organized is an issue for many people. The dolls, doll clothes, shoes, hair items, and the like become a lot to retain. Various ways to store these items are known. They include small opaque and immobile containers. A common problem with all these systems is the lack of organization. Another problem area is the ability for transporting to desired locations. Furthermore with all of these systems access to desired items is difficult. Various attempts have been made to provide an organizer for dolls. Examples of these attempts can be seen by reference to several U.S. patents. U.S. Pat. No. 4,298,127, issued in the name of Upshaw et al., describes a stackable basket assembly. U.S. Pat. No. 5,967,533, issued in the name of Alexander, describes a stackable storage bins which include a wheeled base. U.S. Pat. No. 7,044,569, issued in the name of Relyea et al., describes a modular drawer system with interchangeable components. Additionally, ornamental designs for a doll caddy exist, particularly U.S. Pat. No. D 531,406. However, none of these designs are similar to the present invention. While these systems fulfill their respective, particular objectives, each of these references suffer from one (1) or more disadvantages. Many such systems do not offer adequate organization. Others are limited and do not provide means of transporting. SUMMARY OF THE INVENTION The inventor has recognized the aforementioned inherent problems and lack in the art and observed that there is a need for an organizer for dolls which offers adequate organization and the ease of transporting the system. Accordingly, it is an object of the present embodiments of the invention to solve at least one of these problems. The inventor has addressed this need by developing an organizer for dolls which provides adequate organization and the ease of transporting the system. To achieve the above objectives, it is an object of the present invention to provide a multi-sectional container for organizing, storing, and transporting dolls and doll accessories. Another object of the present invention is to provide a middle compartment, a lower compartment, and an upper compartment which are utilized to organize, store, and transport multiple dolls and doll accessories. Yet still another object of the present invention is to provide an interlocking latching system between the middle, lower, and upper compartments. Yet still another object of the present invention is to provide each compartment with dividers. Yet still another object of the present invention is to provide a pivoting handle upon a rear surface of the middle compartment. Yet still another object of the present invention is to provide wheels and stabilizing fingers upon the lower compartment. Yet still another object of the present invention is to provide a hinged lid upon the upper compartment. Yet still another object of the present invention is to provide an alternate telescoping handle assembly upon the rear surface of the middle compartment. Yet still another object of the present invention is to provide a method of utilizing the device that provides a unique means of motioning the handle, motioning the systems via the wheels, accessing compartments for storage via unlatching and latching latches upon desired compartments, organizing dolls and accessories within the compartments and using the divides to create spaces, and organizing the dolls and accessories. Further objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings in which like elements are identified with like symbols and in which: FIG. 1 is a front perspective view of a doll organizer 10 , according to a preferred embodiment of the present invention; FIG. 2 is a front perspective view of a middle compartment 20 , according to a preferred embodiment of the present invention; FIG. 3 is a rear perspective view of the middle compartment 20 , according to a preferred embodiment of the present invention; FIG. 4 is a cut-away front perspective view of the middle compartment 20 depicting insertion of a middle compartment first divider 36 and a middle compartment second divider 38 , according to a preferred embodiment of the present invention; FIG. 5 is a cut-away front perspective view of the middle compartment 20 depicting placement of the middle compartment first divider 36 and the middle compartment second divider 38 , according to a preferred embodiment of the present invention; FIG. 6 is a front perspective view of a lower compartment 40 depicting insertion of a lower and upper compartment first divider 51 and a lower and upper compartment second divider 53 , according to a preferred embodiment of the present invention; FIG. 7 is a bottom perspective view of the lower compartment 40 , according to a preferred embodiment of the present invention; FIG. 8 is a front perspective view of an upper compartment 60 , according to a preferred embodiment of the present invention; FIG. 9 is a rear perspective view of the upper compartment 60 , according to a preferred embodiment of the present invention; and, FIG. 10 is a rear perspective view of the doll organizer 10 depicting an alternate handle assembly 80 , according to a preferred embodiment of the present invention. DESCRIPTIVE KEY 10 doll organizer 11 doll 12 doll accessory 20 middle compartment 21 middle compartment front panel 22 middle compartment rear panel 23 middle compartment side panel 24 middle compartment interior portion 25 middle compartment upper edge 26 middle compartment front latch 27 middle compartment rear latch 28 middle compartment front protrusion 29 middle compartment rear protrusion 30 middle compartment track 31 handle 32 handle capturing member 33 clamp 34 middle compartment bottom panel 35 middle compartment bottom panel groove 36 middle compartment first divider 37 middle compartment first divider groove 38 middle compartment second divider 40 lower compartment 41 lower compartment front panel 42 lower compartment rear panel 43 lower compartment side panel 44 lower compartment bottom panel 45 lower compartment front latch 46 lower compartment rear latch 47 lower compartment interior portion 48 lower compartment track 49 lower compartment bottom panel groove 50 lower compartment upper edge 51 lower and upper compartment first divider 52 lower and upper compartment first divider groove 53 lower and upper compartment second divider 54 stabilizing finger 55 wheel 56 wheel fork 57 wheel axle 60 upper compartment 61 upper compartment front panel 62 upper compartment rear panel 63 upper compartment side panel 64 upper compartment bottom panel 65 upper compartment upper edge 66 lid 67 lid hinge 68 lid latch 69 lid protrusion 70 upper compartment interior portion 71 upper compartment track 72 upper compartment bottom panel groove 73 upper compartment front protrusion 74 upper compartment rear protrusion 80 alternate handle assembly 81 alternate handle casing 82 alternate handle grasping member 83 sliding member 84 alternate handle track DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The best mode for carrying out the invention is presented in terms of its preferred embodiment, herein depicted within FIGS. 1 through 9 and alternately within FIG. 10 . However, the invention is not limited to the described embodiment, and a person skilled in the art will appreciate that many other embodiments of the invention are possible without deviating from the basic concept of the invention, and that any such work around will also fall under scope of this invention. It is envisioned that other styles and configurations of the present invention can be easily incorporated into the teachings of the present invention, and only one particular configuration shall be shown and described for purposes of clarity and disclosure and not by way of limitation of scope. The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The present invention describes a doll organizer (herein described as the “apparatus”) 10 , which provides a means for a multi-sectional container for organizing, storing, and transporting dolls 11 and doll accessories 12 . It is understood that other, substantially different items may also be stored within the apparatus 10 and the current apparatus 10 is not merely limited to storage and transportation of dolls 11 and doll accessories 12 . Referring now to FIG. 1 , a front perspective view of the apparatus 10 , according to the preferred embodiment of the present invention, is disclosed. The apparatus 10 comprises a middle compartment 20 , a lower compartment 40 , and an upper compartment 60 which are utilized to organize, store, and transport multiple dolls 11 and doll accessories 12 . The middle compartment 20 comprises a larger height than the lower compartment 40 or the upper compartment 60 to enable placement of dolls 11 within the middle compartment 20 and accessories 12 such as outfits, shoes, brushes, or the like within the lower compartment or the lower compartment 60 . Each compartment 20 , 40 , 60 is preferably fabricated from a durable plastic which manufactured in various transparent colors. Referring now to FIGS. 2 through 5 , various views of the middle compartment 20 , according to the preferred embodiment of the present invention, are disclosed. FIG. 2 depicts a front perspective view of the middle compartment 20 , FIG. 3 depicts a rear perspective view of the middle compartment 20 , FIG. 4 depicts a cut-away front perspective view of the middle compartment 20 depicting insertion of a middle compartment first divider 36 and a middle compartment second divider 38 , and FIG. 5 depicts a cut-away front perspective view of the middle compartment 20 depicting placement of the middle compartment first divider 36 and the middle compartment second divider 38 . The middle compartment 20 is utilized to retain a desired amount of dolls 11 within a middle compartment interior portion 24 and is comprised of a middle compartment front panel 21 , a middle compartment rear panel 22 , a pair of opposing middle compartment side panels 23 , and a middle compartment bottom panel 34 . The panels 21 , 22 , 23 , 34 are preferably of an injection molding process which fabricates a single durable structure. The middle compartment panels 21 , 22 , 23 , 34 enable a middle compartment upper edge 25 to retain an underside surface of a lower compartment bottom panel 44 (see FIGS. 6 and 7 ) during storage and transporting purposes. An upper portion of the middle compartment front panel 21 comprises a pair of middle compartment front latches 26 which are integrally molded to an upper perimeter outer surface of the middle compartment front panel 21 and are utilized to fasten the front upper portion of the middle compartment 20 to a front lower portion of the upper compartment 60 (see FIGS. 8 and 9 ). A lower portion of the middle compartment front panel 21 comprises a pair of middle compartment front protrusions 28 which are also integrally molded to an outer surface of the middle compartment front panel 21 . The pair of middle compartment front protrusions 28 enable a front upper portion of the lower compartment 40 (see FIGS. 6 and 7 ) to fasten to the middle compartment 20 . An upper portion of the middle compartment rear panel 22 comprises a pair of middle compartment rear latches 27 which are integrally molded to an upper perimeter outer surface of the middle compartment rear panel 22 and are utilized to fasten the rear upper portion of the middle compartment 20 to a rear lower portion of the upper compartment 60 . A lower portion of the middle compartment rear panel 22 comprises a pair of middle compartment rear protrusions 29 which are also integrally molded to an outer surface of the middle compartment rear panel 22 . The pair of middle compartment rear protrusions 29 enable a rear upper portion of the lower compartment 40 to fasten to the middle compartment 20 . The middle compartment rear panel 22 also comprises a pivoting handle 31 which enables a user to carry the apparatus 10 to a desired location or direct the apparatus 10 to a desired location via simultaneously utilizing a pair of wheels 55 upon the lower compartment 40 . The handle 31 is comprised of a generally “U”-shaped member which is rotatably attached upon opposing ends to a handle capturing members 32 which enables the handle 31 to pivot upwardly for use or downwardly for storage. In use, opposing exterior vertical members of the handle 31 engage a “C”-shaped clamp 33 which secures the handle 31 via friction fit in a vertical orientation. The middle compartment interior portion 24 comprises a plurality of middle compartment tracks 30 upon each panel 21 , 22 , 23 . The middle compartment tracks 30 outwardly extend from each panel 21 , 22 , 23 to retain and guide a middle compartment first divider 36 and to further sectionalize the middle compartment interior portion 24 in a desired matrix. The middle compartment tracks 30 provide a friction fit to each middle compartment first divider 36 which further enables a stabilized installation. The middle compartment first divider 36 is comprised of a rectangularly-shaped preferably plastic section which is slightly smaller than the width of the middle compartment 20 . The middle compartment first divider 26 includes a plurality of middle compartment first divider grooves 37 . The middle compartment first divider grooves 37 are integrally molded to each surface of the middle compartment first dividers 36 to guide a desired amount of middle compartment second dividers 38 . The middle compartment second dividers 38 are comprised of rectangularly-shaped preferably plastic sections which are approximately half the width of the middle compartment first dividers 36 . The middle compartment bottom panel 34 comprises a matrix of middle compartment bottom panel grooves 35 for providing a stabilizing installation which correspond to the various patterns the middle compartment dividers 36 , 38 can create. The middle compartment bottom panel grooves 35 are molded to an upper surface of the middle compartment bottom panel 34 and are slightly larger than the width of the middle compartment dividers 36 , 38 to enable insertion. Referring now to FIG. 6 , a front perspective view of the lower compartment 40 depicting insertion of the lower and upper compartment first divider 51 and the lower and upper compartment second divider 53 and FIG. 7 , a bottom perspective view of the lower compartment 40 , according to the preferred embodiment of the present invention, are disclosed. The lower compartment 40 provides organization and storage to doll accessories 12 . The lower compartment 40 also provides the transporting means to the apparatus 10 . The lower compartment 40 comprises a rectangular shape which is smaller in height than the middle compartment 20 , yet comprises an identical width and depth. The lower compartment 40 is comprised of a lower compartment front panel 41 , a lower compartment rear panel 42 , a pair of lower compartment side panels 43 , and a lower compartment bottom panel 44 which are preferably molded plastic sections similar to the middle compartment 20 . The lower compartment front panel 41 comprises a pair of lower compartment front latches 45 along an outer surface of an upper perimeter edge. The lower compartment front latches 45 are integrally molded to the lower compartment 40 and provide a fastening means to join a front portion of the lower compartment 40 to a bottom front portion of the middle compartment 20 . The lower compartment front latches 45 engage the middle compartment front protrusions 28 in a manner which is similar to conventional storage containers on the market. Likewise, the lower compartment rear panel 42 comprises a pair of lower compartment rear latches 46 along an opposing outer surface of the upper perimeter edge. The lower compartment rear latches 46 are also integrally molded to the lower compartment 40 and provide a fastening means to join a rear portion of the lower compartment 40 to a bottom rear portion of the middle compartment 20 . The lower compartment rear latches 46 engage the middle compartment rear protrusions 29 . In use, the middle compartment bottom panel 34 is positioned upon a lower compartment upper edge 50 aligning the lower compartment latches 45 , 46 with the respective middle compartment protrusions 28 , 29 . A lower compartment interior portion 47 comprises a plurality of lower compartment tracks 48 which are integrally molded to the surface of the lower compartment panel 41 , 42 , 43 . The lower compartment tracks 48 outwardly extend from each panel 41 , 42 , 43 to retain and guide a lower and upper compartment first divider 51 and to further sectionalize the lower compartment interior portion 47 in a desired matrix. The lower compartment tracks 48 provide a friction fit to each lower and upper compartment first divider 51 which further enables a stabilized installation. The lower and upper compartment first divider 51 is comprised of a rectangularly-shaped preferably plastic section which is slightly smaller than the width of the lower compartment 40 . The lower and upper compartment first divider 51 includes a plurality of lower and upper compartment first divider grooves 52 . The lower and upper compartment first divider grooves 52 are integrally molded to each surface of the lower and upper compartment first dividers 51 to guide a desired amount of lower and upper compartment second dividers 53 . The lower and upper compartment second dividers 53 are comprised of rectangularly-shaped preferably plastic sections which are approximately half the width of the upper and lower compartment first dividers 51 . The lower compartment bottom panel 44 comprises a matrix of lower compartment bottom panel grooves 49 to provide a stabilized installation which correspond to the various patterns the lower compartment dividers 51 , 53 can create. The lower compartment bottom panel grooves 49 are molded to an upper surface of the lower compartment bottom panel 44 and are slightly larger than the width of the lower compartment dividers 51 , 53 to enable insertion. An underside surface of the lower compartment bottom panel 44 includes a stabilizing means and a transporting means to the apparatus 10 . A front portion of the underside of the lower compartment bottom panel 44 comprises a pair of integral stabilizing fingers 54 which extend downwardly to engage a level floor surface and to further stabilize the apparatus 10 in a vertical position. Opposing each stabilizing finger 54 and located rearwardly is a wheel 55 which enables the apparatus 10 to be directed along the level surface in conjunction with the handle 31 . Each wheel 55 is attached to the underside of the lower compartment bottom panel 44 by a pair of triangularly shaped wheel forks 56 which are integrally molded and extend downwardly. Each wheel 55 is attached to each respective wheel fork 56 via a wheel axle 57 which further enables the wheels 55 to rotate in a desired direction. Referring now to FIG. 8 , a front perspective view of the upper compartment 60 and FIG. 9 , a rear perspective view of the upper compartment 60 , according to the preferred embodiment of the present invention, is disclosed. The upper compartment 60 also provides additional organization and storage to doll accessories 12 . The upper compartment 60 comprises a rectangular shape which comprises dimensions similar to the lower compartment 40 . The upper compartment 60 is comprised of an upper compartment front panel 61 , an upper compartment rear panel 62 , a pair of upper compartment side panels 63 , and an upper compartment bottom panel 64 which are preferably molded plastic sections similar to the middle compartment 20 . A lower portion of the lower compartment front panel 61 comprises a pair of upper compartment front protrusions 73 outwardly extending from an outer surface thereof, which provide an engaging means from the pair of middle compartment front latches 26 . A lower portion of the lower compartment rear panel 62 also comprises a pair of upper compartment rear protrusions 74 outwardly extending from an outer surface thereof, which provide an engaging means to the pair of middle compartment rear latches 27 . The upper compartment protrusions 73 , 74 enable the upper compartment 60 to be fastened to the middle compartment 20 . An upper compartment interior portion 70 comprises a plurality of upper compartment tracks 71 which are integrally molded to the surface of the upper compartment panels 61 , 62 , 63 . The upper compartment tracks 71 outwardly extend from each panel 61 , 62 , 63 to retain and guide a lower and upper compartment first divider 51 and to further sectionalize the upper compartment interior portion 70 in a desired matrix. The same upper and lower dividers 51 , 53 utilized with the lower compartment 40 are utilized for the upper compartment 60 because of the identical dimensions (see FIGS. 6 and 7 ). The upper compartment bottom panel 64 comprises a matrix of upper compartment bottom panel grooves 72 which correspond to the various patterns the lower and upper compartment dividers 51 , 53 can create. The upper compartment bottom panel grooves 72 are molded to an upper surface of the upper compartment bottom panel 64 and are slightly larger than the width of the lower and upper compartment dividers 51 , 53 to enable insertion. The upper compartment 60 also comprises a lid 66 which encloses the upper compartment interior portion 70 . The lid 66 is attached to a rear perimeter edge of an upper compartment upper edge 65 via a pair of lid hinges 67 . The lid hinges 67 are preferably fabricated from a material similar to the upper compartment 60 and plastic welded to the rear perimeter edge of the upper compartment upper edge 65 and to a rear perimeter edge of the lid 66 . A front edge of the lid 66 comprises an integral lid latch 68 which engages a lid protrusion 69 which is located upon an upper surface of the upper compartment front panel 61 . Referring now to FIG. 10 , a rear perspective view of the apparatus 10 depicting the alternate handle assembly 80 , according to the preferred embodiment of the present invention, is disclosed. The apparatus 10 may alternately comprise an alternate handle assembly 80 which provides a sliding luggage-type handle in lieu of the above-mentioned handle 31 . The alternate handle assembly 80 comprises an alternate handle casing 81 which is molded to a surface of the middle compartment rear panel 22 . The alternate handle casing 81 encloses an alternate handle track 84 which enables a sliding member 83 to travel upon. The sliding member 83 is pulled upwardly in an exposed manner for use and pushed downwardly within the alternate handle casing 81 for storage. An upper portion of the sliding member 83 comprises an alternate handle grasping member 82 which provides a horizontal surface of the user to gasp. It is envisioned that other styles and configurations of the present invention can be easily incorporated into the teachings of the present invention, and only one particular configuration shall be shown and described for purposes of clarity and disclosure and not by way of limitation of scope. The preferred embodiment of the present invention can be utilized by the common user in a simple and effortless manner with little or no training. After initial purchase or acquisition of the apparatus 10 , it would be installed as indicated in FIG. 1 . The method of installing and utilizing the apparatus 10 may be achieved by performing the following steps: acquiring the apparatus 10 ; pivoting the handle 31 to an upward orientation and fastening the each clamp 33 ; directing the apparatus 10 to a desired location via pushing or pulling the handle 31 in a desired direction and enabling the apparatus 10 to travel about the wheels 55 upon a desired level surface; resting the apparatus 10 at a desired location, supported by the wheels 55 and fingers 54 ; unlatching the middle compartment front and rear latches 26 , 26 and removing the upper compartment 60 from the middle compartment 20 ; unlatching the lower compartment front and rear latches 45 , 46 from the middle compartment 20 and removing the middle compartment 20 from the lower compartment 40 ; unlatching the lid latch 68 from the lid protrusion 69 and lifting the lid 66 about the lid hinges 67 to expose the upper compartment interior portion 70 ; inserting a desired amount of lower and upper compartment dividers 51 , 53 into the upper compartment interior portion 70 within the upper compartment track 71 and lower and upper compartment first divider groove 52 as desired; inserting a desired amount of doll accessories 12 into the upper compartment interior portion 70 as desired; latching the lid latch 68 back upon the lid protrusion 69 ; inserting a desired amount of middle compartment dividers 36 , 38 into the middle compartment interior portion 24 within the middle compartment track 30 and middle compartment first divider groove 37 as desired; inserting a desired amount of dolls 11 into the middle compartment interior portion 24 as desired; inserting a desired amount of lower and upper compartment dividers 51 , 53 into the lower compartment interior portion 47 within the lower compartment track 48 and lower and upper compartment first divider groove 52 as desired; inserting a desired amount of doll accessories 12 into the lower compartment interior portion 47 as desired; positioning the underside of the middle compartment bottom panel 34 onto the lower compartment upper edge 50 and latching the lower compartment front and rear latches 45 , 46 onto the respective middle compartment front and rear protrusions 28 , 29 ; positioning the under of the upper compartment bottom panel 64 upon the middle compartment upper edge 25 and latching the middle compartment front and rear latches 26 , 27 upon the upper compartments front and rear protrusions 73 , 74 ; angling the apparatus 10 via the handle 31 and transporting via the wheels 55 as desired; resting in an upright position via the stabilizing fingers 54 as desired; and, providing a means to keep dolls 11 clean and organized. The method of installing and utilizing the apparatus 10 with the alternate handle assembly 80 may be achieved by performing the following steps: sliding the sliding member 83 upwardly from the alternate handle casing 81 and grasping the alternate handle grasping member 82 ; directing the apparatus 10 to a desired location via pushing or pulling the alternate handle grasping member 82 in a desired direction and enabling the apparatus 10 to travel about the wheels 55 upon a desired level surface; resting the apparatus 10 at a desired location, supported by the wheels 55 and fingers 54 ; unlatching the middle compartment front and rear latches 26 , 26 and removing the upper compartment 60 from the middle compartment 20 ; unlatching the lower compartment front and rear latches 45 , 46 from the middle compartment 20 and removing the middle compartment 20 from the lower compartment 40 ; unlatching the lid latch 68 from the lid protrusion 69 and lifting the lid 66 about the lid hinges 67 to expose the upper compartment interior portion 70 ; inserting a desired amount of lower and upper compartment dividers 51 , 53 into the upper compartment interior portion 70 within the upper compartment track 71 and lower and upper compartment first divider groove 52 as desired; inserting a desired amount of doll accessories 12 into the upper compartment interior portion 70 as desired; latching the lid latch 68 back upon the lid protrusion 69 ; inserting a desired amount of middle compartment dividers 36 , 38 into the middle compartment interior portion 24 within the middle compartment track 30 and middle compartment first divider groove 37 as desired; inserting a desired amount of dolls 11 into the middle compartment interior portion 24 as desired; inserting a desired amount of lower and upper compartment dividers 51 , 53 into the lower compartment interior portion 47 within the lower compartment track 48 and lower and upper compartment first divider groove 52 as desired; inserting a desired amount of doll accessories 12 into the lower compartment interior portion 47 as desired; positioning the underside of the middle compartment bottom panel 34 onto the lower compartment upper edge 50 and latching the lower compartment front and rear latches 45 , 46 onto the respective middle compartment front and rear protrusions 28 , 29 ; positioning the under of the upper compartment bottom panel 64 upon the middle compartment upper edge 25 and latching the middle compartment front and rear latches 26 , 27 upon the upper compartments front and rear protrusions 73 , 74 ; angling the apparatus 10 via the alternate handle grasping member 82 and transporting via the wheels 55 as desired; resting in an upright position via the stabilizing fingers 54 as desired; and, providing a means to keep dolls 11 clean and organized. The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention and method of use to the precise forms disclosed. Obviously many modifications and variations are possible in light of the above teaching. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, and to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions or substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but is intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.	A doll organizer to store particularly suited for carrying dolls or similar items along with associated accessories includes a plurality of removably stackable compartments which includes a pair of rolling wheels at a retractable handle. The various compartments are particularly adapted to organize and retain a variety of common doll toy accessories. Additionally, each compartment includes a plurality of removable dividers for organizing the dolls and accessories in a selectable, modular manner. The individual compartments can be removed during use for ease of access to the various toys.	1
FIELD OF THE INVENTION The present invention relates to an ink set for an ink-jet recording method and a recording method using the same. BACKGROUND OF THE INVENTION Of currently practiced ink-jet recording methods, commonly adopted method is a method employing a pale color ink for printing low density areas and a dark color ink for printing high density areas in order to reproduce smooth gradation of the printed images. When ink-jet ink droplets are ejected onto an image receptive layer, dots are formed. Subsequently, said ink droplets penetrate into the interior of said image receptive layer, and at the same time, said ink droplets spread over the surface of said image receptive layer whereby dots adjacent to each other spread while being partially united. When the added amount of dyes is markedly different between the pale ink and the dark ink, the surface tension of the pale ink is frequently different from that of the dark ink, even though surface active agents in the same amount are added. The surface tension also varies depending on the type of dyes. Further, when colorants penetrate deep into portions of said ink receptive layer, the optical density of images often decreases. Accordingly, the dot diameter of each color ink varies over an elapse of time, and the depth distribution of colorants also varies, whereby color variation occurs. When the spread of colorants of the pale ink becomes different from that of the dark ink over a long period of time, the gradation of high density areas formed employing the dark ink is not allowed to be continuous with that of low density areas formed employing the pale ink after an elapse of time. Namely, when density variation between the low density areas and the high density areas is not balanced, the gradation is deteriorated over an elapse of time, whereby problems occur in which smooth gradation is not assured. When ink comprised of water-soluble dyes is used, said problems are particularly exhibited. Furthermore, when the density of each color varies at an almost equal rate, color variation is not exhibited. However, when the density of each color is not balanced, color variation is further exhibited. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink set capable of maintaining smooth gradation over an elapse of time after printing images, and also capable of maintaining color balance. Said object can be achieved employing the embodiments described below. 1. An ink set for ink-jet recording, comprising: a group of inks exhibiting the same hue and having different color densities and containing a colorant, water-soluble organic solvent and water, wherein among the group of inks, an ink has a largest surface tension σ1 and another ink has a smallest surface tension σ2, and said σ1 and said σ2 satisfy the following conditional formula: σ2/σ1>0.7, and wherein at least one of the inks contains iron ions, magnesium ions, calcium ions such that a total amount of the iron ions, the magnesium ions and the calcium ions is not more than 10 ppm by weight. 2. The ink set of item 1, wherein the inks each contain the iron ions of 0.01 to 3 ppm by weight. 3. The ink set of item 1, wherein the inks each contain the magnesium ions of not more than 2 ppm by weight. 4. The ink set of item 1, wherein the inks each contain the magnesium ions of 0.01 to 2 ppm by weight. 5. The ink set of item 1, wherein the inks each contain the calcium ions of not more than 3 ppm by weight. 6. The ink set of item 1, wherein the inks each contain silicon of not more than 10 ppm by weight. 7. The ink set of item 1, wherein the inks each contain nickel of not more than 2.0 ppm by weight. 8. The ink set of item 1, wherein the ink each contain barium of not more than 2.0 ppm by weight. 9. The ink set of item 1, wherein the inks each contain zinc of not more than 2.0 ppm by weight. 10. The ink set of item 1, wherein the inks each contain chromium of not more than 2.0 ppm by weight. 11. The ink set of item 1, wherein the inks each contain strontium of not more than 1.0 ppm by weight. 12. The ink set of item 1, wherein the inks each contain aluminum of not more than 5.0 ppm by weight. 13. The ink set of item 1, wherein the inks each contain zirconium of not more than 10 ppm by weight. 14. The ink set of item 1, wherein the inks each contain zirconium of not more than 2.0 ppm by weight. 15. The ink set of item 1, wherein the inks each contain manganese of not more than 2.0 ppm by weight. 16. The ink set of item 1, wherein an ink of the group of inks contains sodium ions of not more than 500 ppm by weight. 17. The ink set of item 1, wherein the inks each contain potassium ions of not more than 500 ppm by weight. 18. The ink set of item 1, wherein the inks each contain a complexing agent. 19. The ink set of item 1, wherein said σ1 and said σ2 satisfy the following conditional formula: σ2/σ1>0.85. 20. The ink set of item 1, further comprising: another group of inks exhibiting the same another hue and having different color densities and containing a colorant, water-soluble organic solvent and water, wherein among all groups of inks, an ink has a largest surface tension (max and another ink has a smallest surface tension σmin, and said σmax and said σmin satisfy the following conditional formula: σmin/σmax>0.6. 21. The ink set of item 1, further comprising: a second group of inks each ink of which has a different color density of the same second hue and contains a colorant, water-soluble organic solvent and water, the same second hue different from the same hue of the group of inks, and a third group of inks each ink of which has a different color density of the same third hue and contains a colorant, water-soluble organic solvent and water, the same third hue different from the same hue of the group of inks and the same second hue of the second group of inks, so that the ink set comprises seven different inks or more, wherein among each of the second group of inks and the third group of inks, an ink has a largest surface tension σ1 and another ink has a smallest surface tension σ2, and said σ1 and said σ2 satisfy the following conditional formula: σ2/σ1>0.7. 22. The ink set of item 19, further comprising: a second group of inks each ink of which has a different color density of the same second hue and contains a colorant, water-soluble organic solvent and water, the same second hue different from the same hue of the group of inks, and a third group of inks each ink of which has a different color density of the same third hue and contains a colorant, water-soluble organic solvent and water, the same third hue different from the same hue of the group of inks and the same second hue of the second group of inks, so that the ink set comprises seven different inks or more, wherein among each of the second group of inks and the third group of inks, an ink has a largest surface tension σ1 and another ink has a smallest surface tension σ2, and said σ1 and said σ2 satisfy the following conditional formula: σ2/σ1>0.85. 23. The ink set of item 20, wherein at least two of the inks exhibit black color and have different color densities. 24. The ink set of item 1, wherein the inks each contain a dihydric alcohol of not less than 50% by weight of water-soluble organic solvents contained in said ink. 25. An ink-jet recording method comprising the step of: jetting an ink of the ink set of item 1 from an ink-jet head to an ink-jet recording media; wherein the recording media comprises a support having thereon a porous ink receptive layer containing inorganic particles and a hydrophilic binder. 26. The ink-jet recording method of item 25, wherein the inorganic particles are made of silica. 27. The ink-jet recording method of item 26, wherein the the porous ink receptive layer contains voids having a diameter of 10 to 100 nm. 28. The ink-jet recording method of item 27, wherein the porous ink receptive layer contains a cationic fixing agent. DETAILED DESCRIPTION OF THE INVENTION The present invention will now be detailed. In the present invention, colored inks of the same color with different color density are prepared in such a manner that, for example, dark cyan and pale cyan inks are prepared by varying the concentration of cyan dyes. The concentration of dyes of pale inks is preferably from {fraction (1/10)} to ½ of that of dark inks. Colorants are not particularly limited to, for example, pigments and dyes. However, since dyes are more diffusible, effects of the present invention is more exhibited. Listed as dyes are acidic dyes, direct dyes, basic dyes, reactive dyes, or food dyes. Representative dyes are listed below. However, the present invention is not limited to these dyes. <Direct Dyes> C.I. Direct Yellow 1, 4, 8, 11, 12, 24, 26, 27, 28, 33, 39, 44, 50, 58, 85, 86, 100, 110, 120, 132, 142, and 144 C.I. Direct red 1, 2, 4, 9, 11, 134, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 47, 48, 51, 62, 63, 75, 79, 80, 81, 83, 89, 90, 94, 95, 99, 220, 224, 227 and 343 C.I. Direct Blue 1, 2, 6, 8, 15, 22, 25, 71, 76, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 163, 165, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 236, and 237 C.I. Direct Black 2, 3, 7, 17, 19, 22, 32, 38, 51, 56, 62, 71, 74, 75, 77, 105, 108, 112, 117, and 154 <Acidic Dyes> C.I. Acid Yellow 2, 3, 7, 17, 19, 23, 25, 20, 38, 42, 49, 59, 61, 72, and 99 C.I. Acid Orange 56 and 64 C.I. Acid Red 1, 8, 14, 18, 26, 32, 37, 42, 52, 57, 72, 74, 80, 87, 115, 119, 131, 133, 134, 143, 154, 186, 249, 254, and 256 C.I. Acid Violet 11, 34, and 75 C.I. Acid Blue 1, 7, 9, 29, 87, 126, 138, 171, 175, 183, 234, 236, and 249 C.I. Acid Green 9, 12, 19, 27, and 41 C.I. Acid Black 1, 2, 7, 24, 26. 48, 52, 58, 60, 94, 107, 109, 110, 119, 131, and 155 <Reactive Dyes> C.I. Reactive Yellow 1, 2, 3, 14, 15, 17, 37, 42, 76, 95, 168, and 175 C.I. Reactive Red 2, 6, 11, 21, 22, 23, 24, 33, 45, 111, 112, 114, 180, 218, 226, 228, and 235 C.I. Reactive Blue 7, 14, 15, 18, 19, 21, 25, 38, 49, 72, 77, 176, 203, 220, 230, and 235 C.I. Reactive Orange 5, 12, 13, 35, and 95, C.I. Reactive Brown 7, 11, 33, 37, and 46 C.I. Reactive Green 8 and 19 C.I. Reactive Violet 2, 4, 6, 8, 21, 22, and 25 C.I. Reactive Black 5, 8, 31, and 39 <Basic Dyes> C.I. Basic Yellow 11, 14, 21, and 32 C.I. Basic Red 1, 2, 9, 12, and 13 C.I. Basic Violet 3, 7, and 14 C.I. Basic Blue 3, 9, 24, and 25 Other than those as cited above, listed as dyes capable of being employed in the present invention may be chelate dyes and azo dyes which are employed in so-called silver dye bleach process light-sensitive materials (for example, Cibachrome, manufactured by Ciba-Geigy). Chelate dyes are described, for example, in British Patent No. 1,077,484. Azo dyes of said silver dye bleach method light-sensitive materials are described, for example, in British Patent Nos. 1,039,458, 1,004,957, and 1,077,628, and U.S. Pat. No. 2,612,448. Employed as pigments capable of being used in the present invention may be organic and inorganic pigments, conventionally known in the art. Listed as examples are azo pigments such as azo lakes, insoluble azo pigments, condensation azo pigments, and chelate-azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye lakes such as basic dye lakes and acidic dye lakes, organic pigments such as nitro pigments, nitoroso pigments, aniline black, and daylight fluorescence pigments; and inorganic pigments such as carbon black. Listed as water-soluble organic solvents employed in the present invention are the examples below. It is possible to employ alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, and benzyl alcohol); polyhydric alcohols (for example, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, 1,2-buranediol, 1,4-butanediol, 1,2-pentanediol, thiodiglycol, glycerin, and pentaerythritol); polyhydric alcohol ethers (for example, as ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether); amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, and tatramethylpropylenediamine); amides (for example, formamide, N,N-dimethylformamide, and N,N-dimethylacetamide; heterocycles (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrrolidone, 2-oxazolidone, and 1,3-dimethyl-2-imidazilidinone); sulfoxides (for example, dimethylsulfoxide); sulfones (for example, sulfolane); sulfonate salts (for example, sodium 1-butanesulfonate); urea; acetonitrile; and acetone. Of these, from the viewpoint of improvement of gradation variation during extended storage, dihydric alcohols are preferably incorporated into water-soluble organic solvents in an amount of at least 50 percent of said water-soluble organic solvents. Dihydric alcohols are preferably ethylene glycol, propylene glycol, 1,2-butanediol, 1,4-butanediol, and 1,2-pentanediol. Of these, ethylene glycol, as well as propylene glycol, is particularly preferred. In the present invention, in order to adjust the surface tension of ink, surface active agents may be incorporated. Listed as surface active agents, preferably used in the ink of the present invention, are anionic surface active agents such as dialkyl sulfosuccinates, alkylnaphthalenesulfonates, and higher fatty acid salts; nonionic surface active agents such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers; and cationic surface active agents such as alkylamine salts and quaternary ammonium salts. Of these, it is most preferable to employ anionic surface active agents. A method for preparing each ion of silicon, nickel, barium, zinc, chromium, strontium, aluminum, zirconium, manganese, sodium, potassium, calcium, magnesium, and iron, will now be described. The concentration of an aqueous dye solution at the specified concentrating is determined employing ICP-AES (Inductively Coupled Plasma-Atomic Emmision Spectroscopy). An ion concentration in a state of ink is calculated in terms of the dye concentration employed in said ink. It is possible to estimate the ion concentration during formation of ink, employing water, distilled water, or deionized water. Subsequently, ink is prepared by adding other additives, and said ion concentration of the resulting ink is determined employing ICP-AES. When the resulting ion concentration exceeds the target value, it is possible to decrease the ion concentration by passing said aqueous dye solution through ion exchange resins. It is possible to further decrease said ion concentration by passing said aqueous dye solution a plurality of times. When said ion concentration does not reach the desired value through said operations, additives other than dyes may be subjected to treatments such as ion exchange. Further, if desired, treatments such as an activated carbon treatment and filtration utilizing ultrafiltration membranes may be further carried out. An image receptive sheet will now be described. Said image receptive sheet comprises a support having thereon an ink receptive layer, and further may have a sublayer between said support and said ink receptive layer. Ink Receptive Layer The ink receptive layer, as described herein, refers to the layer which receives ink droplets ejected from an ink-jet head, and is comprised of fillers such as fine organic particles to facilitate ink absorption, and binders. Listed as examples of fine inorganic particles may be white inorganic pigments such as precipitated calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, alumina, colloidal alumina, pseudo boehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide. Silica is particularly preferred. Preferably employed as binders used in said ink receptive layer are hydrophilic binders, and it is possible to employ hydrophilic binders conventionally known in the art in ink-jet recording sheets. For example, listed may be gelatin, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, carboxymethyl cellulose, hydroxyethyl cellulose, agar, and dextrin. Of these, polyvinyl alcohol, which exhibits excellent film forming properties, is particularly preferred. The saponification ratio and average degree of polymerization of used polyvinyl alcohol are preferably from 70 to 100 percent and from 2,000 to 5,000, respectively, and are more preferably from 80 to 99 percent and from 2,200 to 4,500, respectively. In addition to common polyvinyl alcohol which is obtained by hydrolyzing polyvinyl acetate, said polyvinyl alcohol includes modified polyvinyl alcohol which is obtained by being subjected to cationic modification of the terminals, or anionic modification. The content of said fine inorganic particles incorporated into said ink receptive layer is commonly from 5 to 30 g per m 2 of the recording sheet, and is preferably from 10 to 25 g. Further, the weight ratio of said fine inorganic particles to said hydrophilic binders is preferably from 1 to 15, and is more preferably from 1.5 to 8. Cationic fixing agents are preferably incorporated into said ink receptive layer. Listed as said cationic fixing agents are cationic polymers and fine inorganic particles having a cationic surface. Employed as said dationic polymers may be those conventionally known in the art in ink-jet recording sheets. Listed as these are compounds described in said ink-jet printer techniques and materials, and Japanese Patent Publication Open to Public Inspection No. 9-193532. Cationic polymers, particularly preferred in the present invention, are polymers having a quaternary ammonium salt group at the main or side chain of said polymers, and include dimethylamine epihydrin condensation products, polydiallyldimethylammonium salts or copolymers thereof, homopolymers or copolymers of vinylbenzyltrimethylammonium salts, homopolymers or copolymers of N,N,N-trimethyl aminoethyl acrylate chloride, and homopolymers or copolymers of N,N,N-trimethyl aminoethyl methacrylate chloride. Specific examples of cationic polymers having said quaternary ammonium salt group, which are preferably employed in the present invention, are illustrated below. The number average molecular weight of said cationic polymers is preferably from 2,000 to 100,000, and is mast preferably from 3,000 to 80,000. The used amount of said cationic polymers is commonly in the range of 0.1 to 10 g per m 2 of the recording sheet, and is preferably in the range of 0.2 to 5 g. Fine inorganic particles having a cationic surface include, for example, alumina, pseudo boehmite, cation-modified silica, which is subjected to a surface treatment employing aluminum, and silica particles prepared by allowing the silica particle surface having an anionic surface to react with a group (such as a trimethoxysilyl group) capable of reacting with the cationic group as well as silica particles. For the purpose of improvement of film forming properties and an increase in water resistance, organic or inorganic cross-linking agents of said hydrophilic binders may be employed in said ink receptive layer. Listed as said preferable cross-linking agent is boric acid. However, from the viewpoint of the stabilization of gradation in the early stage, it is preferable to employ boric acid together with cross-linking agents other than said boric acid. EXAMPLES The present invention will now be specifically described with reference to examples. However, the embodiments of the present invention are not limited to these examples. Example A Preparation of Image Receptive Layer 1 Preparation of Support Both surfaces of a 200 g/m 2 paper substrate were covered with PE (polyethylene) comprised of a mixture of titanium oxide containing HDPE (high density polyethylene), and LDPE (low density polyethylene), to obtain a coated layer thickness of 31 μm, employing a melt extrusion method. The surface was subjected to corona discharge treatment and subsequently provided with a gelatin sublayer. Onto said gelatin sublayer, the coating composition having the composition described below was applied to obtain a wet layer thickness of 180 μm, employing a slide hopper system, whereby an ink receptive layer at a dried layer thickness of 40 μm was provided. Thus, Image Receptive Layer 1 was prepared. Composition of Coating Composition (per liter): Silica synthesized employing a gas 90 g phase method (QS-20, manufactured by Tokuyama) Cationic polymer P-13 8 g Polyvinyl alcohol (having an average 10 g degree of polymerization of 3,500 and a saponification ratio of 88 percent) Polyvinyl alcohol (having an average 5 g degree of polymerization of 4,500 and a saponification ratio of 88 percent) Boric acid 0.8 g Borax 0.4 g Saponin 0.10 g Betaine type fluorine based surface 0.02 g active agent FS-1 The coating composition was prepared as follows. After dispersing silica powder into deionized water, an aqueous cationic polymer solution, boric acid and borax, an aqueous solution prepared by mixing two types of polyvinyl alcohol, saponin, and FS-1 were successively added. Coating was carried out at 40° C. After said application, the coating was temporarily cooled at 5° C. for 10 seconds. Thereafter, drying was carried out over 20 seconds employing a 20° C. air flow, followed by 1 minute employing a 65° C. air flow, 1 minute employing a 50° C. air flow, and 1 minute employing a 40° C. air flow. The average void diameter was determined at an initial pressure of 0.1 MPa, employing a mercury porosimeter (Shimadzu Pore Analyzer type 9220), resulting in the average void diameter of 20 nm. Preparation of Image Receptive Layer 2 Image Receptive Layer 2 was prepared in the same manner as Image Receptive Layer 1, except that cationic polymer P-13 was not employed. Preparation of Ink Set 1 (Example 1) Ten percent aqueous solution of each of the dyes described below was passed through activated carbon, and subsequently passed three times through ion exchange resins. Further, the resulting solution was subjected to ultrafiltration, and the decreased water amount was supplemented with deionized water. Pale Cyan Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Acid Blue 9 (10 percent aqueous 7.5 weight parts solution) Preventol (manufactured by Bayer Co.) 0.2 weight part Proxel (manufactured by Zeneca 0.04 weight part Pharmaceuticals) Deionized water to make 100 weight parts Dark Cyan Ink Ethylene glycol 15 weight parts Propylene glycol 25 weight parts Acid Blue 9 (10 percent aqueous 36 weight parts solution) Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Preparation of Ink Set 2 (Comparative Example 2) Ink Set 2 was prepared in the same manner as Ink Set 1, except that 10 percent aqueous solution of each of said dyes was not subjected to each of said active carbon treatment, ion exchange treatment, and ultrafiltration, and water was replaced with well water. Preparation of Ink Set 3 (Example 3) A ten percent aqueous solution of each of dyes described below was passed through active carbon, and subsequently passed three times through ion exchange resins. Further the resulting solution was subjected to ultrafiltration, and decreased water was supplemented with deionized water. Pale Magenta Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Acid Red 52 (10 percent aqueous 9.57 weight parts solution) Surface Active Agent (Orufin E1010, 0.05 weight part manufactured by Nisshin Kagaku Co.) Preventol 0.2 weight part Proxel 0.04 weight part 1 mol/L NaOH 0.032 weight part Deionized water to male 100 weight parts Dark Magenta Ink Ethylene glycol 7.5 weight parts Propylene glycol 40 weight parts Acid Red 52 (10 percent aqueous 38.25 weight parts solution) EDTA4Na 0.3 weight part Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Preparation of Ink Set 4 (Example 4) Ink Set 4 was prepared in the same manner as Ink Set 3, except that 10 percent aqueous solution of each of said dyes was passed through active carbon and once through ion exchange resins, and was not subjected to ultrafiltration. Pale Magenta Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Acid Red 52 (10 percent aqueous 9.57 weight parts solution) Surface active agent (Orufin E1010) 0.05 weight part Preventol 0.2 weight part Proxel 0.04 weight part 1 mol/L NaOH 0.032 weight part Deionized water to make 100 weight parts Dark Magenta Ink Ethylene glycol 7.5 weight parts Propylene glycol 40 weight parts Acid Red 52 (10 percent aqueous 38.25 weight parts solution) EDTA4Na 0.3 weight part Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Preparation of Ink Set 5 (Example 5) A ten percent aqueous solution of each of dyes described below was passed through active carbon, and subsequently passed three times through ion exchange resins. Further the resulting solution was subjected to ultrafiltration, and decreased water was supplemented with deionized water. Pale Yellow Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Direct Yellow 86 (10 percent aqueous 1.97 weight parts solution) Acid Yellow 79 (10 percent aqueous 10.24 weight parts solution) Preventol 0.2 weight part Proxel 0.04 weight part 1 mol/L NaOH 0.028 weight part Deionized water to make 100 weight parts Dark Yellow Ink Ethylene glycol 18 weight parts Propylene glycol 27 weight parts Direct Yellow 86 (10 percent aqueous 7.88 weight parts solution) Acid Yellow 79 (10 percent aqueous 40.95 weight parts solution) Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Pale Magenta Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Acid Red 249 (10 percent aqueous 9.57 weight parts solution) Surface active agent (Orufin E1010) 0.05 weight part Preventol 0.2 weight part Proxel 0.04 weight part 1 mol/L NaOH 0.032 weight part Deionized water to make 100 weight parts Dark Magenta Ink Ethylene glycol 7.5 weight parts Propylene glycol 40 weight parts Acid Red 249 (10 percent aqueous 38.25 weight parts solution) EDTA4Na 0.3 weight part Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Pale Cyan Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Direct Blue 199 (10 percent aqueous 9.23 weight parts solution) Surface active agent (Orufin E1010) 0.1 weight part Preventol 0.2 weight part Proxel 0.04 weight part 1 mol/L NaOH 0.032 weight part Deionized water to make 100 weight parts Dark Cyan Ink Ethylene glycol 7.5 weight parts Propylene glycol 40 weight parts Direct Blue 199 (10 percent aqueous 36.9 weight parts solution) Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Each of a pale black ink and a dark black ink was prepared by blending materials described below followed by passing ion exchange resins. Pale Black Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Direct Yellow 86 (10 percent aqueous 4.69 weight parts solution) Direct Red 249 (10 percent aqueous 7.88 weight parts solution) Direct Blue 199 (10 percent aqueous 5.91 weight parts solution) Surface active agent (Orufin E1010) 0.05 weight part Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts Dark Black Ink Ethylene glycol 24 weight parts Propylene glycol 22 weight parts Deionized water 42 weight parts Direct Yellow 86 (powder) 2.94 weight parts Acid. Red 249 (powder) 3.96 weight parts Direct Blue 199 (powder) 2.5 weight parts Surface active agent (Orufin E1010) 0.08 weight part Preventol 0.2 weight part Proxel 0.04 weight part Deionized water to make 100 weight parts The metal ions in each of said inks were determined employing ICP-AES (SPS-4000, manufactured by Seiko Denshi Kogyo). Preparation of Ink Set 6 (Example 6) Ink Set 6 was prepared in the same manner as Ink Set 5, except that Pale Black Ink as well as Pale Yellow Ink was not employed. Preparation of Ink Set 7 (Example 7) Ink Set 7 was prepared in the same manner as Ink Set 5, except that Dark Cyan Ink and Pale Cyan Ink were replaced with those of Ink Set 2. Comparative Set (Comparative Example 2) A Comparative Set was prepared in the same manner as Ink Set 5, except that activated carbon, ion exchange, and ultrafiltration treatments were not carried out. Printing Each ink of said ink sets was ejected at the conditions described below, employing the ink-jet head utilizing a piezo electric ceramic described in Japanese Patent Publication Open to Public Inspection No. 11-99644. Each of Examples 1 through 7 and Comparative Examples 1 and 2 was recorded on Image Receptive Sheet 1. Ejection Conditions Driving frequency: 30 kHz Volume of droplet: 7 pl Recording density: 720 dpi (herein, dpi refers to the number of dots per 2.54 cm) Recording Image: by varying the dot density per unit area, an image having gradation was prepared. Dots formed by a dark ink and a pale ink were arranged so as to result in smooth connection of gradation one minute after image recording Storage Conditions of Images Images were visually observed one minute after printing, and then the resulting images were also visually observed 3 hours, 24 hours, and one week after being stored at 23° C. and 60 percent relative humidity. Method for Measuring Surface Tension The surface tension of each sample was determined at 23° C. and 55 percent relative humidity, employing a Wilhelmie type surface tensiometer. Evaluation Gradation Continuity A: gradation continuity was smooth during one-week storage B: degradation of gradation continuity was noticed when observed after one-week storage C: degradation of gradation continuity was noticed when observed after 24-hour storage D: degradation of gradation continuity was noticed when observed after 3-hour storage. Color Balance in Low Density Area and High Density Area. A: color balance was maintained from the low density area to the high density area during one-week storage B: color balance varied when observed after one-week storage C: color balance varied when observed after 24-hour storage D: color balance varied when observed after 3-hour storage. TABLE 1 Example Comparative Example Example Example Example Example Comparative 1 Example 1 3 4 5 6 7 Example 2 Dark surface tension (mN/m) 45.0 26.0 47.0 47.0 45.0 24.0 Cyan Ca + Mg + Fe (ppm) 5.0 22.0 9.0 9.0 5.0 25.0 Ink Mg (ppm) 1.5 6.5 1.0 1.0 1.5. 6.5 Ca (ppm) 2.5 12.0 1.0 1.0 2.5 16.0 Pale surface tension (mN/m) 43.0 39.0 41.0 41.0 43.0 36.0 Cyan Ca + Mg + Fe (ppm) 2.5 16.0 3.0 or less 3.0 or less 2.5 12.0 Ink Mg (ppm) 0.5 5.0 0.5 or less 0.5 or less 0.5 3.0 Ca (ppm) 1.0 10.0 0.5 or less 0.5 or less 1.0 4.5 Cyan σ2/σ1 0.96 0.67 0.87 0.87 0.96 0.67 Ink Dark surface tension (mN/m) 49.0 32.0 47.0 47.0 47.0 22.0 Magenta Ca + Mg + Fe (ppm) 5.0 11.0 7.0 7.0 7.0 42.0 Ink Mg (ppm) 1.5 3.0 1.5 1.5 1.5 19.0 Ca (ppm) 2.0 2.0 2.0 2.0 2.0 29.0 Na 120 120 120 2700 K 200 200 200 3500 Si 1.0 1.0 1.0 35.0 Ni 1.0 or less 1.0 or less 1.0 or less 11.0 Ba 1.5 1.5 1.5 9.5 Zn 0.8 0.8 0.8 8.0 Cr 1.0 or less 1.0 or less 1.0 or less 5.5 Sr 0.5 or less 0.5 or less 0.5 or less 5.0 Mn 1.7 1.7 1.7 10.5 Al 5.0 or less 5.0 or less 5.0 or less 18.0 Zr 1.3 1.3 1.3 13.0 Pale surface tension (mN/m) 43.0 41.0 43.0 43.0 43.0 40.0 Magenta Ca + Mg + Fe (ppm) 2.5 6.0 3.0 or less 3.0 or less 3.0 or less 16.0 Ink Mg (ppm) 0.5 1.5 0.5 or less 0.5 or less 0.5 or less 6.5 Ca (ppm) 1.0 2.0 1.0 1.0 1.0 9.0 Na 26 26 26 660 K 48 48 48 830 Si 1.0 or less 1.0 or less 1.0 or less 12.0 Ni 1.0 or less 1.0 or less 1.0 or less 3.5 Ba 1.0 or less 1.0 or less 1.0 or less 3.0 Zn 1.0 or less 1.0 or less 1.0 or less 3.0 Cr 1.0 or less 1.0 or less 1.0 or less 2.5 Sr 0.5 or less 0.5 or less 0.5 or less 1.5 Mn 1.0 or less 1.0 or less 1.0 or less 3.0 Al 5.0 or less 5.0 or less 5.0 or less 7.0 Zr 1.0 or less 1.0 or less 1.0 or less 3.0 Magenta σ2/σ1 0.88 0.78 0.91 0.91 0.91 0.55 Ink TABLE 2 Example Comparative Example Example Example Example Example Comparative 1 Example 1 3 4 5 6 7 Example 2 Dark surface tension (mN/m) 47.0 47.0 47.0 28.0 Yellow Ca + Mg + Fe (ppm) 5.0 5.0 5.0 33.0 Ink Mg (ppm) 1.5 1.5 1.5 9.5 Ca (ppm) 1.5 1.5 1.5 13.0 Pale surface tension (mN/m) 49.0 49.0 46.0 Yellow Ca + Mg + Fe (ppm) 3.0 or less 3.0 or less 11.0 Ink Mg (ppm) 0.5 or less 0.5 or less 3.5 Ca (ppm) 0.5 or less 0.5 or less 4.0 Yellow σ2/σ1 0.96 0.96 0.61 Ink Dark surface tension (mN/m) 41.0 41.0 41.0 22.0 Black Ca + Mg + Fe (ppm) 3.5 3.5 3.5 16.0 Ink Mg (ppm) 1.0 1.0 1.0 4.5 Ca (ppm) 1.0 1.0 1.0 6.0 Pale surface tension (mN/m) 41.0 41.0 32.0 Black Ca + Mg + Fe (ppm) 3.0 or less 3.0 or less 11.0 Ink Mg (ppm) 0.5 or less 0.5 or less 2.5 Ca (ppm) 0.5 or less 0.5 or less 3.5 Black σ2/σ1 1.00 1.00 0.69 Ink Entire 0.84 0.87 0.84 0.48 Ink Effects gradation A C A B A A C D continuity during storage color balance in A B C D low density and high density areas Number 8 colors 6 colors 8 colors 8 colors of Colors Example B Printing was carried out in the same manner as Example 5, except that Image Receptive Sheet 2 which does not contain a cationic polymer p-13 was employed, and the same evaluation was conducted. The evaluation results were as follows: gradation continuity was “C” and color balance was “B”. As proved in the examples, the ink set and recording method according to the present invention exhibit excellent effects which make it possible to maintain smooth gradation over a long period of time after printing and, further, to maintain color balance over a long period of time after printing.	An ink set for ink-jet recording comprising a group of inks exhibiting the same hue and having different color densities and containing a colorant, water-soluble organic solvent and water, wherein among the group of inks, an ink has a largest surface tension σ1 and another ink has a smallest surface tension σ2,and said σ1 and said σ2 satisfy the following conditional formula: σ2/σ1>0.7, and wherein at least one of the inks contains iron ions, magnesium ions, calcium ions such that a total amount of the iron ions, the magnesium ions and the calcium ions is not more than 10 ppm by weight.	2
This is a division of co-pending application 08/088,767 filed Jul. 8, 1993, now U.S. Pat. No. b 5,348,078. FIELD OF THE INVENTION This invention relates to a system for controlling heating and air conditioning within a building. BACKGROUND OF THE INVENTION It is known to supply and control heating and ventilation from a centralized source. Buildings are often built with dampers and temperature sensors within air ducts. These dampers can be controlled from a centralized location. Examples of this technology may be found in U.S Pat. No. 4,585,163 (the '163 patent), U.S. Pat. No. 4,732,318 (the '318 patent), U.S. Pat No. 4,406,397 (the '397 patent), and U.S. Pat. No. 4,646,964 (the '964 patent). A common problem of the devices cited in these patents is the difficulty and expense involved in fitting an already constructed building with a heating and air conditioning system. This problem of retrofittability is solved with the present invention. One of the reasons the devices cited in prior art are difficult to fit into existing buildings is that their dampers are located within the air ducts. Most of the these dampers are single blade devices. Single blade dampers need significant amounts of space (about equal to the width or height of a damper, depending on the pivot direction) to reach a fully opened state. The space requirement, therefore, dictates that these single blade dampers be positioned within the actual duct, rather than at the duct outlet or opening. This single blade design can be seen in the '318 patent, the '964 patent, the '397 patent, and the '163 patent. U.S. Pat. No. 4,258,877 (the '877 patent), issued Mar. 31, 1981, to White, discloses an electric, motor driven damper, with thermostatic switch control, for opening and closing air ducts. The actuator also shows the damper position from outside the duct, by the use of an indicator arm on the damper pivot. Like those devices mentioned above, the White damper blade must be located within the actual air conditioning duct. This is because the damper blade is comprised of an L-shaped member having a relatively long leg and a relatively short, slightly curved leg. The relatively long leg is rotatably mounted to a shaft which is mounted perpendicular to the flow of air. Therefore, the relatively long leg of the damper blade would be parallel or at an angle to the sides of the air conditioning duct. This would prevent this damper blade from being used directly behind the duct opening. Since the damper must be located within the air conditioning duct, retrofitting is impractical. U.S. Pat. No. 2,790,372, issued Mar. 30, 1963, to Cooper, discloses an electric, motor driven damper, controlled by a thermostat, to increase the flow of cool/heated air into the individual rooms. There is no provision for controlling the temperature of the incoming air or for controlling the overall system temperature. The damper in this patent only functions in conjunction with an air supply duct which extends horizontally above the ceiling of a room and has a duct opening on its lower side. This single blade damper requires significant amounts of room to swing open. Therefore, like those dampers discussed above, this damper would not be easily retrofittable and, additionally, would be limited to a specific type of duct. There are many methods of regulating individual room air temperature. The invention disclosed in the '318 patent issued Mar. 22, 1988, to Osheroff, regulates individual room air temperature by increasing the velocity of the heated or cold air through the ducts. The invention disclosed in the '397 patent, issued Sep. 27, 1983, to Kamata, regulates air temperature in an individual room by using an air quantity control device in each branched duct of a central heating and air conditioning system. The air quantity delivered to each room is monitored by velocity sensors in each branch duct, and the command sent to the central blower unit for either increased or decreased air volume. The invention disclosed in the '163 patent, issued Apr. 29, 1986, to Cooley, regulates air temperature by monitoring air volume. It also should be noted that most of the prior art systems have sensing devices which are located within the air ducts. This is true in the '318 patent, the '397 patent, the '163 patent, and the '964 patent. This requirement makes retrofitting difficult. The '964 patent, issued Mar. 3, 1987, to Parker, addresses the opening and closing of a duct, and the air temperature in the duct. The room temperature is set by a thermostat in the individual room, and commands the duct to open and close, based on the difference between room temperature and air duct temperature, measured by a sensor in the duct. This system cannot control individual room temperature by commanding the heater/air conditioner to add cooler air or heat, and relies on the main thermostat, for the overall temperature condition. Accordingly, a principal object of the present invention is to provide an improved heating and air conditioning system which is easily retrofittable to a single family dwelling with a single duct system. BRIEF SUMMARY OF THE INVENTION In accordance with the present invention, a heating and air conditioning system for a single family dwelling, preferably includes a heater and air conditioning furnace system, a series of output ducts extending from the furnace system to individual rooms or zones of the dwelling, controllable output register units (often called vent units) at each duct opening into a zone, thermostats for each individual zone, and a central controller for controlling the furnace system and the individual zone registers. The system preferably also includes a master controller for selecting temperature conditions for each zone and for sending signals to a central controller. This heating and air conditioning system is designed to be easily retrofitted into existing homes. One reason for the ease of retrofitting the present invention is its unique register assemblies. Preferably, these register assemblies have specially designed exterior frames made of side and corner units which allow the register to fit almost any duct opening, and an inner register unit. The exterior frame compensates for uneven walls such that the inner register unit remains undistorted. These register assemblies replace existing system dampers which require installation within existing air ducts. The inner register unit of the invention has fully sealing, interlocking inner vanes or blades which are attached to a blade bar that may be electronically controlled by a central controller. Each register unit may be provided with a small motor (or servo) which controls its open/close state. The servo unit may be hardwired to or controlled via radio signals by the central controller. A second set of snap-in, adjustable blades may be provided at the front of the inner unit for directing air as desired within the local room or zone. Thermostat units, preferably in each room, would monitor the room temperature. They would preferably be able to communicate with the central controller over house AC wiring or via a radio type transmitter and receiver. They would also provide the user with a source for controlling for the individual room temperature. Additionally, the system would preferably include a master controller which could include an alternate source of control for the individual zones, a centralized source of control for the zones combined, and a timing means of control. The master controller would preferably communicate with the central controller over existing house AC wiring or via radio signals. In addition to controlling and communicating with the room thermostats, the master controller and the register assemblies, the central controller may control the actual heating and air conditioning furnace. The preferred embodiments of the invention may also include the following additional features: 1. The register assemblies may be either manually controlled or servo controlled. 2. The servo controlled register assemblies may be hardwired to the central controller or controlled via a radio-type receiver. 3. The individual zone thermostat may be mounted in a standard electrical outlet, mounted in a specially designed junction box in the wall, or connected to a table stand. 4. The frame of the inner register unit (interior frame) may be mounted to the exterior frame of the register unit by way of a molded serrated pull tap or a steel spring clip. A major advantage of the present invention is that this system is easily retrofitted into a currently existing building. This is due, in part, to its unique register units or vent covers which can be placed at the opening of the air duct rather than a damper which is fitted within the actual duct. The retrofitability is also due to the ability of the system to communicate over standard building AC wiring or via radio signals. Another major advantage of the present invention is having the temperature of an individual zone measured within the actual zone. The present invention measures the temperature at the individual zone thermostat. This feature provides more accurate temperature control within the zone than those systems which measure the temperature from within the air duct. Other objects, features and advantages of the present invention will become apparent from a consideration of the following detailed description, and from the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a building having individual control zones connected by air ducts, each zone having its own thermostat and register assembly, the building also having a master controller and a central controller; FIG. 2 is a perspective partially exploded view of a servo controlled register assembly incorporating certain features of the present invention; FIG. 3 is a front view of the register assembly; FIG. 4 is a top view of a servo controlled register assembly; FIG. 5 is a cross-sectional top view of the side of the register assembly taken along line 5--5 of FIG. 3; FIG. 6 is a cross-sectional side view of the top of the register assembly taken along line 6--6 of FIG. 3; FIG. 7 is an enlarged perspective view of the corner coupling unit of the exterior register frame taken along line 7--7 of FIG. 3; FIG. 8 is a cross-sectional view taken along lines 8--8 if FIG. 7 including an extruded side unit; FIG. 9 is a perspective partially cutaway view of a manually controlled register assembly; FIG. 10 is perspective view of a self powered, radio frequency controlled unit for the register; FIG. 11a is a front view of an individual zone thermostat; FIG. 11b is a side view of an individual zone thermostat; FIG. 11c is a side view of an individual zone thermostat with a table stand; FIG. 11d is a view of an individual zone thermostat mounted in a junction box; FIG. 12a is a master controller including details of the display screen and the control pad; FIG. 12b is a front view of the master controller with a pivoted panel or door covering the control pad switches; FIG. 12c is a side view of the master controller with the door shut; FIG. 13a is a block circuit diagram of the room thermostat circuit; FIG. 13b is a block circuit diagram of the power/communication circuit of a hardwired room thermostat circuit; FIG. 13c is a block circuit diagram of a radio controlled room thermostat circuit; FIG. 14 is a block circuit diagram of the servo unit at each self powered, radio frequency controlled register; FIG. 15a is a block circuit diagram of a hardwired central controller; FIG. 15b is a block circuit diagram for a radio controlled central controller; FIG. 16 is a block diagram of the program implemented by the Read Only Memory (ROM) of the central controller; FIG. 17a is a diagram of converted digital signals; FIG. 17b represents high frequency signals to be transmitted over AC 120 volt house wiring; FIG. 18 is a depiction of the sequences of control signals transmitted by the central controller, the master controller, and the thermostat units; FIG. 19a is a block circuit diagram of the master controller circuit; FIG. 19b is a block circuit diagram of the power/communication circuit of a hardwired master controller; FIG. 19c is a block circuit diagram of a power/communication circuit of a radio controlled master controller; FIG. 20a is a block diagram of the connection between each of the servoregisters and the central controller; and FIG. 20b is a variable pulse width signal for servo motor control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. General Referring more particularly to the drawings, FIG. 1 is a depiction of a dwelling heating and air conditioning system 26 installed in a building 28. The building 28 in accordance with a preferred embodiment of the invention may be a dwelling 28; however, other types of buildings such as businesses or recreational facilities could employ the same system. The dwelling 28 may contain multiple individual rooms or zones 42. The zones 42 are preferably connected by a series of ducts 40 for supplying heating and air conditioning to the zones 42. In each zone 42 there may be one or more openings of the duct 40. During installation of the system 26, each opening is preferably covered by a register assembly (or vent assembly) 30. Additionally, each zone 42 preferably contains a thermostat 50 which may be connected to a central controller 60. The building 28 may also be equipped with a master controller 70 which may communicate with the central controller 60. The central controller 60 preferably controls the actual heating, air conditioning, and fan unit 44 of the dwelling heating and air conditioning system 26. II. Register Assembly A. Exterior Frame Each zone 42 of a building 28 may contain a register assembly 30 which includes an exterior frame 32. FIG. 2 is a perspective view of a register assembly 30 controlled by a servo motor 80, and detailing the exterior, duct adapting, register frame (exterior frame)32, and an inner register unit 33. The exterior register frame 32 (also shown in FIG. 3) serves to accommodate uneven wall openings; and it is preferably composed of corner members 36 and side members 38. The comer member 36 (as shown FIG. 7) may have a square central portion 46 with two legs 48 extending from the central unit 46 and at right angles to each other. The legs 48 are thinner than the central portion 46, of the corner members 36 and extend outwardly from it. The legs 48 may then be inserted into the L-shaped extruded side members 38 (as shown in both FIG. 7 and FIG. 8). The exterior, duct-adapting, register frame 32 is uniquely suited to the retrofitting feature of the present invention. The corner members 36 may be made of a standard size. The side members 38 are preferably made by an extrusion process involving forcing heated plastic through a die. The extruded side unit 38 can be made in a continuous process, and then cut to fit any size duct opening. An alternative embodiment of the exterior frame 32, albeit less economical, would be to use a molded frame or molded side units. Extruding, however, is more economical than the expensive process of molding an entire frame or four side units. Additionally, if a molded frame or side unit was used, many sizes would be needed to fit the various sized duct openings used in residential and commercial buildings. The side members 38 may be cemented or otherwise bonded to the corner units 36 to form complete exterior frames 32. Finally, as shown in FIG. 2, one or more fastening holes 35 can be included on the exterior register frame 32. These holes 35 can be used to secure the register assembly 30 to the wall or surface surrounding the duct opening, or to the outwardly ranged ends of the duct. B. Inner Register Unit The inner register unit 33 (as shown in FIG. 2) is preferably comprised in part of a frame (interior frame) 34, outer directional vanes or blades 180, and inner sealing vanes or blades 182. The outer blades 180 have been removed at the left in FIG. 2 to show the inner vanes 182. FIG. 2 shows one embodiment of the present invention including air directional blades (air deflectors) 180 in the foreground and the surface-engaging, interlocking, sealing blades 182 in the background (discussed below in connection with FIG. 5). FIG. 3 is a front view of the register unit 30. In this view the frame of the inner register unit (interior frame) 34 is positioned within the exterior, wall compensating and duct-adapting, register frame 32. FIG. 5 and FIG. 6 further detail the interface between the exterior frame 32 and the interior frame 34. These frames are preferably sealed together by way of interior/exterior rubber compliant sealing strips 37 which may be bonded to the outer wall of the interior frame 34. The exterior frame 32 is sealed to a wall or other surface by way of a compliant rubber strip 39 which is bonded within a recess of the extruded side units 38 exterior frame 32 (as seen in FIG. 5 and 6). These seals are necessary to prevent passage of air through gaps between the register unit frames (34 and 32) and the exterior frame 32 and the surface to which the register unit is mounted. As shown in FIG. 2, the interior frame 34 may be held securely within the exterior frame 32 by a molded serrated pull tab 31. An alternative embodiment could include a spring steel clip to position the interior frame 34 within the exterior frame 32. Other fastening devices and seals known in the art would allow the interior frame 34 to be secured and sealed within the exterior frame 32 and the register to control air flow even if the wall or structure that the exterior frame 32 rests against is not flat. FIG. 4 shows a top view of a servo controlled register assembly 30. (The actual mechanics of the servo unit 80 will be discussed in more detail in connection with FIG. 10 and FIG. 14.) The servo unit 80 may be used to control the position of the servo lever 189. In the preferred embodiment of the invention the lever 189 has only two positions, open and closed, corresponding to the signals represented in FIG. 20b; however, other embodiments could include three or more positions or a continuous spectrum of positions. The servo lever 189 is preferably pivotally attached to each end of a stiff wire or thin connecting rod 192. The other end of the stiff wire 192 may be pivotally attached to the blade bar extension 194 which preferably extends perpendicularly from the blade bar 190. An alternative embodiment of the invention could have the wire 192 attached directly to the blade bar 190. Another alternative embodiment of the invention could use a manual lever 188 (as detailed in FIG. 9). The manual lever 188 would preferably include a handle or knob 187 extending into the room. Further, the manual lever 188 would preferably be pivotally connected to the blade bar extension 194. 1. Inner Interlocking Vanes The blade bar 190 preferably has pivotally attached to it an array of inner, interlocking vanes or blades 182 for selectively shutting off the air flow through the register assembly 30. The inner vanes 182 are preferably attached to the blade bar 190 on the outer edge by way of blade pivot extensions 185 (as shown in FIG. 4 and FIG. 6) which may extend perpendicularly from the upper edges of the blades 182. The blade pivot extensions 185 are pivotally attached to the blade bar 190 by the pivot screw 196. FIG. 5 details a horizontal cross section of the frame of the inner register unit (interior frame) 34 including the inner, interlocking vanes 182. These vanes 182 are preferably pivotally attached to the interior frame 34 by pivot means 183. In one embodiment of the invention the pivot means includes a small cylindrical pivot disk 183 which is attached to one end of an interlocking inner vane 182. The cylindrical pivot disk 183 would then fit into a receiving notch 205 of a receiver bar 204. A receiver bar cover strip 206 may be used to cover the receiving notches 205 with the cylindrical pivot disks 183 "snapped in" so that the disks 183 are held in place. Alternatively, the notches may be configured so that the pivot disks snap into the notches so that the receiver bar cover strip is not needed. Other pivot means 183 such as pivot screws and other known pivot arrangements may be employed. The interlocking vanes 182 are preferably rectangular-shaped and may have dimensions, for example, of 41/2" high and 11/4" wide. The dimensions are preferably such that the blades extend past the opening 200 defined by the interior frame blade ridge 198. The interior frame blade ridge 198 preferably has affixed to it a rubber or foam blade compliant seal 199. When the blades 182 are in the closed position, they rest against the blade complaint seal 199 so that no air can pass. The horizontal cross sections of the interlocking vanes 182 preferably have an essentially rectangular with cut-out rectangular portions at opposite diagonal comers (184 and 186). This cross section may be achieved by specifically extruding or molding the individual inner vanes 182, by molding a rectangular unit and "cutting out" the corner sections, or by combining two flat sections. If two flat sections were combined, each section, for example, be 41/2" long, 7/8" wide, and approximately 1/16" thick. The flat sections would then be coupled in a offset fashion so that about 1/4" of the width of each section overlaps the other flat section. At the edge of the inner vane 182 by the cylindrical pivot disk 183, the cut-out portion forms an "under-engaging" surface 186. At the other end of the vane 182, the cut-out portion forms an "over-engaging" surface 184. When the vanes 182 are in the closed position, the over-engaging surface 184 rests on the nearest underengaging vane surface 186. In combination with the vanes `overextension` of the perimeter onto the compliant seal, this produces a fully sealing engagement which effectively shuts off the flow of air through the register assembly 30. 2. Outer Air-deflecting Blades Also shown in FIG. 5 and FIG. 6 is an array of air-deflecting, outer vanes or blades 180 which may be pivotally attached to the interior frame 34. These blades 180 may be manually set to direct the flow of air to the desired location within the room 42 in which the register assembly 30 is located. The air-deflecting outer blades 180 may be molded or extruded in either a bent or a straight configuration. These blades 180 should to fit in the interior frame 34 of the inner register unit 33, for example, 5" in length At both ends of each blade 180, the blades are pivotally mounted to the frame 30 by pivot pins 181 mounted either on the blades 180 or the frame 30, which snap into mating C-shaped "snap in" receiver 179 mounted on the frame 30 or the blade 180, respectively. This allows for easy assembly and replacement of broken vanes 180. Further, it allows the vanes 180 to be positioned so that the air deflects left or right. C. Control of the Register Unit As discussed in connection with FIG. 4, the interlocking vanes 182 are pivotally connected to a blade bar 190. The blade bar 190 may be controlled by a manual lever 188 (as detailed in FIG. 9), or it may be controlled electronically by a servo unit 80. If the blade bar 190 is controlled by a servo unit 80, the servo unit may be connected directly or indirectly via a power assembly 81 and receiving circuit 86, see FIG. 10, to the central controller 60. 1. Hardwired As shown in FIG. 10, the servo unit 80 has three input wires: a ground wire 95, a power wire 96, and a pulse width wire 97 for receiving a variable signal. In the directly connected electronic embodiment, these wires may be directly "hardwired" to the central controller 60 (at 413,414, and 415 in FIG. 15a). The wires may run through or alongside the ducts 40. 2. Radio Controlled Alternatively, the indirect or radio controlled electronic embodiment would include a self-contained power source 81 and a receiving circuit 86 to the servo 80. The receiving circuit 86 preferably receives signals emitted from a radio-type transmitter located in the central controller 60, as discussed below in connection with FIG. 15b. This embodiment would not require "hardwiring" and therefore would add to the ease of retrofitability. The servo unit 80, as shown in FIG. 10 is preferably fixed to a motor bracket 82. Under or behind the bracket 82, and electronically connected to the servo 80, is the power source 81 which would be used in the self-contained power embodiment. The power source includes batteries 88, the charge of which is maintained by an impeller 94 which is connected to a motor generator 92. The impeller 94 rotates as air passes which causes the generator 92 to charge the rechargeable lithium cells or other batteries such as sealed lead acid cells 88. The lithium cells 88 need to be trickle-charged. However, they are preferable to nicad batteries which have shorter shelf lives than the lithium batteries. The lithium cells 88 are connected to circuit 84 which selectively supplies power to the servo 80 and includes a battery sensor 362 of FIG. 14. FIG. 14 is a block diagram of the control circuit for a servo equipped register 30. When the battery sensor 362 senses that the batteries 88 need to be charged, a signal is sent to the servo logic 356. The servo 80 then opens the register assembly 30. As air passes through the assembly 30, the impeller 94 turns. This causes the generator 92 to charge the batteries 88. FIG. 14 further shows the communication means between the register assembly 30 and the central controller 60 in the wireless embodiment. Each servo unit 80 may be equipped with a modular "phone-type" pigtail (approximately one foot long) connected to a female jack. This pigtail may be hardwired directly to the central controller 60 (wires 413,414 and 415 of FIG. 15a). Alternatively, the pigtail wires (95, 96 and 97) of the servo unit 80 may be connected to the power assembly wires (93, 98 and 94). These wires are preferably connected to a receiving circuit 86 (as seen in FIG. 10), which includes an antenna 366 and a 900 Mhz receiver 350 (as seen in FIG. 14). The receiving circuit 86 picks up signals emitted by the receiver/transmitter 424 of the central controller of FIG. 15b. When the central controller 60 transmits signals to the servo equipped register 30, the signal may then be sent to a wake up unit 358 within the processor 360 and to a spread spectrum logic device 352. The wake up unit 358 signals the spread spectrum logic unit 352, a decoder 354, and a servo logic unit 356. This spread spectrum logic 352 passes the signal to the decoder 354 within the processor 360 which in turn extracts or decodes the original information from the transmitted signal. The signal is sent to the servo logic unit 356 which in turn signals the servo unit 80 to either open or close the appropriate register unit 30. FIG. 20a shows the hardwire connection (or implied radio signal connection) between the servo 80 which controls the register unit 30 (as shown in FIG. 2) and the central controller 60. The register servo signal from the central controller 60 sends a variable pulse signal 204 (as detailed in FIG. 20b). For example, if the pulse width is approximately 1 millisecond (Ms), the servo is closed. When the signal from the central controller to the servo 80 is 2 Ms, the register unit 30 is opened. Alternate embodiments could include additional, intermediate settings of the servo in which the register unit 30 is partially opened. III. Individual Zone Thermostat Each zone 42 which contains a register unit 30 preferably includes an individual zone thermostat 50. Each individual zone thermostat 50 has preferred physical embodiments which are discussed below in connection with FIGS. 11a through 11d. The preferred control scheme of the individual zone thermostat circuit 301 is discussed below in connection with FIG. 13a. If the system 26 is hardwired, the power/communication circuit 348 of FIG. 13a is depicted as 348' of FIG. 13b. If the system is radio controlled, the power/communication circuit 348 of FIG. 13a is depicted as 348" of FIG. 13c. FIGS. 13a, 13b, and 13c will be discussed below. A. Physical Characteristics FIG. 11a details a preferred embodiment of the individual zone thermostat 50. The thermostat unit, as shown, may have a digital display screen 100 which could be, for example, approximately 1 inch by 2 inches. The display screen would preferably display information about the current status of the dwelling heating and air conditioning system 26 and the local zone 42. More specifically the display screen 100 of the thermostat unit 50 would highlight information pertinent to the individual room or zone 42. By way of example, information which could be displayed includes: the mode of operation of the system (heat, A/C, "auto" or fan) 102; the status of the system (on or off) 104; the temperature to which the room is set 106; whether the switch actuation is locked 107; the status of the room (on or off) 108; and the actual temperature of the room 109. Also included in the thermostat unit 50 are switch controls for setting the individual zone thermostat 50. By way of example, a mode button 56, an up button 58, and a down button 59 are included in the preferred embodiment of the invention. There is also a hole 57 to provide access to an inner switch for locking the switch actuation. This locking feature is advantageous for use in zones or rooms 42 which small children frequent. As best shown in FIG. 11b, the individual zone thermostat 50 is equipped with a 110 volt blades or plug prongs 52 for coupling with the standard house receptacle. An alternative means of connecting the thermostat unit 100 to the main system would be the use of a table stand 54 (as best shown in FIG. 11c) into which the plug prongs 52 could be coupled. FIG. 11d depicts another embodiment of the present invention in which the thermostat 50' may be mounted in a junction box 51 and covered with a faceplate 53. B. Control Circuit FIG. 13a is a block diagram of the preferred embodiment of the room thermostat circuit 301. The room thermostat 50 is preferably controlled by a microprocessor 300 which may include 4K ROM (four thousand bytes of Read Only Memory). This microprocessor 300 receives information about the zone 42 in which the thermostat 50 is located including the temperature of the room as indicated by a circuit 328, the temperature at which the zone 42 is set, and information on the house and unit (or zone) codes supplied by circuits 322 and 304. The user uses buttons (56, 58, 59 of FIG. 11a), controlled by the switches 320, to set temperature and otherwise communicate with the room thermostat circuit 50. The buzzer 306 provides an audible "beep" to indicate when a button has been depressed. The microprocessor 300 is connected to a display driver 316 which controls the LCD display 318 of the thermostat 50 (as best shown in FIG. 11a). Finally, the room thermostat 50 has a circuit 348 for power and communication. Information regarding the temperature of the zone 42 is supplied by a thermistor 328. The thermistor 328 changes resistance according to the temperature of the zone 42. A constant current 330 is supplied to the thermistor, and the varying output voltage is then converted from analog to digital form by a serial A/D converter 324. The reference circuit 326 emits a constant 2.5 V as a frame of reference for the system to calibrate the circuit and reliably determine the temperature of a zone 42. Other information relevant to the microprocessor 300 is obtained from the house code switch 322, the unit or room code switch 304, and the push button switches 320. There is also a power up reset 334 for resetting the thermostat 50, an EEPROM 332, and a LCD display 318 and driver 316 to communicate information to the user. Any time there is a change, i.e. in set temperature or a mode change, this information is stored in the non-volatile EEPROM. If there is a power outage causing the power-up reset to "reset", the EEPROM stored information is utilized when power is restored to place the unit in the last commanded state. The power communication circuit 348 of the room thermostat circuit 301 is depicted in its hardwired embodiment as 348' of FIG. 13b. In this embodiment, the room thermostat circuit 301 uses the standard house AC wiring 314 for power and for communicating with the central controller 60. Power from the house AC wiring 314 enters the power supply 310. The power supply 310 supplies 5 volts to the room thermostat circuit 301 through a regulator 312. The power supply 310 also supplies 12 volts to the modem 308. The 12 volts are regulated by a zener diode 340. Communication signals may also be sent through the house wiring 314 to and from the modem 308. The modem is controlled by a timing crystal 338 to send and receive messages at 120 KHz. The modem 308 then transfers the message to the room thermostat circuit 301. In a radio controlled system 26 the power communication circuit 348 of FIG. 13a is depicted as 348" of FIG. 13c. Like the hardwired system 26, the radio controlled system 26 is plugged into standard AC house wiring 314 for power. This power is fed into a power supply 310 which sends a regulated 5 volts to the room thermostat circuit 301. The power supply 310 also supplies 12 volts to a receiver/transmitter 344. The 12 volts are regulated by a zener diode 340. Communication is accomplished via an antenna 342 and a 900 MHz receiver/transmitter 344. The receiver 344 using spread spectrum logic, communicates the information to the room thermostat circuit 301. Information may also be sent from the room thermostat circuit 301 to the central controller 60 via the receiver/transmitter 344 and the antenna 342. IV. Master Controller FIG. 12a shows the master controller 70 of the system 26. The primary functions of the master controller 70 is to assist in the programmability of system operation and to change a zone's parameters remotely. Like the room thermostats 50, the master controller 70 may control the temperature of each individual room. The master controller 70, in its preferred embodiment, controls the set temperature of all the rooms to provide separate temperature environments, if desired. The master controller 70 may also control the set temperature in one or all of the zones 42 according to date and time. A. Physical Characteristics In the preferred embodiment, the master controller 70 has a display screen 72 and a control pad 74. As seen in FIG. 12b the control pad 74, when not in use, would be covered by door 76. As seen in FIG. 12c the door 76 will be connected by hinging means 79 at the bottom of the master controller 70. The door 76 would be held closed by pull tabs 78 which secure the door to the control pad 74. The display screen 72 of the master controller 70 (as best seen in FIG. 12a) would include information regarding the status of the dwelling heating and air conditioning system. In FIG. 12a the door 76 is deleted for clarity. Such status information might include various zones 120, current temperatures 122, set temperatures 124, the register status 126, the time at which the system is set to turn on in a particular room 128, the time at which the system is set to turn off in a particular room 130, the days on which the timer is set to turn on 132, and the temperature to which the timer is set to adjust the system 134. The master control switch pad 74 (as best seen in FIG. 12a) provides various controls for setting and adjusting the dwelling heating and air conditioning system. By way of example, the control pad 74 would include controls for the zone 140, the timer 142, and the clock 144. Other controls could be provided for turning the system on or off 150, for displaying various groups of zones 148, and for labeling the zones 146. The zone controls 140 would include up and down buttons (151 and 152) for the zone under consideration, up and down buttons (153 and 154) for setting the system temperature, and a mode button (155). The timer controls 142 would include up and down buttons (156 and 157) for the "turn on" time, up and down buttons (158 and 159) for the "turn off" time, and up and down buttons (160 and 161) for the timer temperature. Also preferably included in the timer controls 142 would be a button (162) for setting the day, a button (163) to enter the day, a button (164) to clear the timer, and a button (165) to copy the timer information to all zones. The clock set controls 144 would include up and down buttons (166 and 167) for the hour, up and down buttons (168 and 169) for the minute, and a button (170) to set the day. The zone label controls 146 would include left and right buttons (171 and 172) for the cursor, left and fight buttons (173 and 174) for the character, a button (175) to restore, and a button (176) to set the memory. The controls for the zone display 148 might include a button (137) for displaying zones 1 through 8 and a button (138) for displaying zones 9 through 15. There would also be a button (150) for turning the system off. B. Control Circuit FIG. 19a shows a block circuit diagram of the master controller 70. The master controller circuit 530 is controlled by a microcontroller 534 with timing set by a quartz timing crystal 536. The microcontroller sends out and receives local information over the data bus 552 and address bus 554. The microcontroller circuit may also include 8K RAM 540 which the microcontroller 534 may access. Preferably them is also a PAL switch interface 542 which connects to the buttons on the master controller key pad 74 via switches 550. A timer clock 544 may be included to allow the user to control temperature at specific times of the day. A PAL LCD driver 546 and an LCD 548 make up the components for driving the display screen 72. Finally, a power communication circuit 532 is included to communicate with the central controller 60. The power communications circuit 532 of FIG. 19a is detailed in its hardwired embodiment as 532' of FIG. 19b. The power communication circuit 532 is detailed in its radio controlled embodiment as 532" of FIG. 19c. The hardwired embodiment of the power communication circuit 532 of the master controller circuit 530 is shown as 532' of FIG. 19b. In this embodiment, the master controller 70 communicates with the central controller 60 via standard house AC wiring 564. Power, also is supplied by the house wiring 564, enters the power supply 560 which sends a regulated 562 5 volts to the master controller circuit 530 and 12 volts to the power line modem 556. The 12 volts are regulated by a zener diode 566. Communication is achieved as signals are sent through the house wiring 564 to and from the modem 556. The modem 556 is controlled by a timing crystal 558 to send and receive messages at 120 KHz. The modem 556 then transfers the signal to the master controller circuit 530. In a system 26, operated by radio control, the power communication circuit 532 of FIG. 19a is represented as 532" of FIG. 19c. Like the hardwired system 26, the radio controlled system 26 is plugged into standard AC house wiring 564. The AC wiring 564 feeds power into a power supply 560. The power supply 560 provides 5 volts to the master controller circuit 530 and 12 volts to a receiver/transmitter 570. The 5 volts are regulated by the regulating circuit 562 and the 12 volts are regulated by a zener diode 566. Communication is achieved as an antenna 568 picks up signals which are received by a 900 MHz receiver/transmitter 570. The receiver 570 using spread spectrum logic, communicates the information to the master controller circuit 530. Information is also sent from the master controller circuit 530 to the central controller 60 via the receiver transmitter 570 and the antenna 568. V. Central Controller The central controller 60 preferably provides the central point of communication and control for the heating and air conditioning system 26. The central controller 60 may communicate with the individual zones 42 by sending out "instructions" to each thermostat 50. It may also receive "responses" as to the "temperature state" of each thermostat 50. The central controller 60 communicates with the master controller 70 by sending out "instructions" and receiving "responses." Another important function of the central controller 60 is to control the servo controlled room registers 30. Finally, the central controller 60 turns on and off the heater, air conditioning system, and fan 44 as needed, based on the "in condition" of the individual thermostats 50. FIG. 15a shows the preferred embodiment of the central controller 60 in a hardwired system 26. FIG. 15b details the preferred embodiment of the central controller 60 in a radio controlled system 26. FIG. 16 shows the preferred embodiment of a sequence of steps that the central controller 60 takes to accomplish its functions. The steps may be dictated by a program in the memory (390 and 400) of the central controller 60. FIG. 18 details the communication "instructions" and "responses" used by the central controller 60. A. Control Circuit As shown in FIG. 15a and 15b, the central controller 60 is equipped with a microprocessor 400 which has its timing controlled by a quartz timing crystal 416. Extra non-volatile memory is provided by an EEPROM 390, for back-up purposes as disclosed hereinabove. The preferred program stored in ROM is discussed below in connection with FIG. 16. Information regarding the temperature is supplied by a thermistor 394. The thermistor 394 changes resistance according to temperature. A constant current 392 is supplied to the thermistor, and the varying output voltage is then converted from analog to digital form by a serial A/D convertor 398. The reference circuit 396 emits a constant 2.5 volts as a frame of reference for the system to calibrate the circuit and reliably determine the proper temperature. Other information relevant to the microprocessor includes a power up reset 386, and a house code switch 388. The microprocessor 400, based on information it receives from the room thermostats 50 and the master controller 70, controls the furnace and air conditioner 44. This is done by three triac units 404 which control the heat, air, and fan (406, 408, and 410). The microprocessor 400 can also control the speed of the fan by using a motor speed control unit 402 to control the HVAC 426. FIG. 15a specifically embodies the configuration of a central controller 60 which is hardwired to the system 26. The register servos 80 are hardwired (414 to 96, 415 to 97, and 413 to 95 as shown in FIG. 15a and FIG. 10) in queue fashion 412 to the microprocessor 400. This enables the central controller 60 to poll the register servos one at a time. The microprocessor 400 communicates to the room thermostats 50 via a quartz crystal 418 controlled modem 384 which sends out signals via standard AC wiring 420. The AC wiring 420 is also connected to a transformer 382 which in turn is connected to a power supply 380 which supplies power to the central controller 60. FIG. 15b shows the radio controlled embodiment of the central controller 60. Communication to the master controller 70, the room thermostats 50, and the servo controlled registers 30 is done using radio signals. The microprocessor 400 sends and receives signals to and from a 900 MHz receiver/transmitter 424 which uses spread spectrum logic and over an antenna 422 to an appropriate device. Signals from these devices are received through the antenna 422 and the 900 MHz receiver/transmitter 424 and return to the microprocessor 400 for processing. This radio controlled central controller 60 is powered by standard house AC wiring 420. The power goes through a transformer 382 to a power supply 380 which supplies power to the central controller 60. B. Control Steps FIG. 16 is a block diagram of a preferred embodiment of the program contained in the ROM of the central controller 60. Once the power has been turned on 430 the compressor timer is preferably set to five minutes 432. This five minute period allows the pressure in the compressor to equalize and thereby prevents damage to the compressor. A check may then be done on the data integrity and the backup EEPROM 434. If the check comes out "bad," the HVAC is turned off 450. If, however, the check comes out "good," then the temperature setting and status is sent to all the remote register units 436. A signal is then sent out to the servo controlled registers 30 so that all the vents are closed 438. The timer is then set for a 3.5 minute countdown 440. After the countdown, a loop is preferably begun which requests the status, the temperature setting, and the current temperature from the zone (1-16) at which the loop is working 442. If there is no reply from the current zone, the program looks at the integrator of the current zone 444. Each of the 16 zones has an integrator which resets to 5 after each reply on the zone. If, however, there is no reply, the integrator is decremented by 1. Each time there is no reply from the current zone remote thermostat, and the integrator is greater than zero, the program may assume the status quo. If, however, the integrator is zero, the program may assume the room is off status. The program may then check to see if the current status of the system equals the remote status 446. If the current status does not equal the remote status, then the system status may be changed to the remote status 448, the change may be broadcasted to all of the remotes 456, and the next zone (1-16) may receive a request for status, setting, and current temperature 442 from the system. If, however, the current status equals the remote status 446 then the program reacts based on that status (458, 460, 462, 464, and 466). If the status of the system is the heating mode 458 then the program preferably looks to see if the temperature is less than or equal to the set temperature by 2° or more 468. If it is less than the set temperature by 2° or more and the heat is on, then the system may open the vent 478. If it is not less than the set temperature by 2°, the vent may be closed 476. However, if this is the last active heat zone, the heat may be turned off 476. If the status of the system is the air conditioning mode 460, then the program may compare to see if the temperature is greater than or equal to the set temperature by more than 2° 470. If the temperature is greater than the set temperature by more than 2°, the vent may be opened and the air conditioning may be turned on if the compressor timer is equal to zero 482. If the temperature is not greater than or equal to the temperature by 2°or more, then the vent may be closed. If this is the last active air conditioning zone, the air conditioning may be turned off and the compression timer is preferably started at five minutes 480. If the status is set to the fan mode 462, then the fan may be turned on and the vent may be opened 472. If the status is set so that the room is turned off 464, then the vent may be closed, unless it is the last vent polled 474. If the status of the system is that the system is turned off 466, then the entire heating, ventilation, and air conditioning (HVAC) may be turned off 450. If this is not the last zone to be polled 484, then the next zone may be looked at 442. However, if this is the last zone to be polled 484 and the number of active vents is less than 50% of the total vents, then the slow blower motor may be turned on if the system is in the air conditioning mode 486. The system may then look to see if there is a master controller 488 included in the system. If there is a master controller, the program may look to see if the data in the master controller matches the data in the central controller 490. If it does not match, then the remotes that differ are updated 492 and the next (first) zone is examined 442. If the data in the master controller matches the data in the central controller 490, the program may then look to see that the plenum temperature is below 34° 452. If there is no master controller 488, the system immediately checks the plenum temperature 452. If the plenum temperature is not below 34°, then the timer countdown may be started at 3.5 minutes 440. If the plenum temperature is below 34° 452, if the air conditioning is on, then it is turned off and the compressor timer may be set 454. If, however, the air conditioner is not on, then this step may be ignored. Either way, the timer countdown is preferably set to 3.5 minutes. C. Control Communications As mentioned above, the central controller 60 may communicate with the thermostats 50, the master controller 70 and the register units 30 via radio signals or through house AC wiring and hardwiring run through the air ducts. The actual signals would preferably be analog signals. For example, FIG. 17b represents an analog high frequency signals transmitted over AC 120 volts house wiring. The figure shows a signal which represents a one 508 and a signal which represents zero 510. FIG. 17a represents the analog signals converted to digital one 504 and digital zero 506 which corresponding to the analog signals. Digital ones 504 and zeros 506 are strung together to form 8 bit hex words which, in turn, are strung together to form instructions and responses. The instructions are detailed in FIG. 18. The central controller 60 sends out various instructions. Each instruction preferably has a standard 8 bit starting word, for example, AA. Each instruction transmission preferably has a standard 8 bit ending word, for example, BB. The instruction preferably includes an 8 bit word indicating the instruction type. Other 8 bit words which may be included in an instruction are the house code, a vent or register code, a status code, an offset code, a parity or check sum (cksum) code, a new temperature setting code, and a master controller code. Instruction types may include a request status, an update status, a broadcast command (to all thermostats), a temperature set offset (which would be done at the factory to calibrate the variation found in silicon chips), a query for the master controller, and instructions to the master controller. This list is meant to be exemplary, and is not meant to be limiting. The thermostat 50 may send responses to the central controller 60 by a similar string of 8 bit hex words. The response may begin with a standard 8 bit hex word different from the starting word of the central controller instruction, for example, 55. The transmission may end with a standard 8 bit word, for example, BB. Other 8 bit words in a thermostat response may include a house code, a thermostat code, a status code, a temperature set code, a current temperature code, and a parity or check sum code. If there was more than one type of thermostat response, a response "type code" may also be included. The master controller 50 may send responses to the central controller 60 by a similar string of 8 bit hex words. The response may begin with a standard 8 bit hex word different from the starting words of the central controller instruction or the thermostat response, for example, CC. The transmission may end with a standard 8 bit word, for example, BB. Other 8 bit words in a master controller response may include a house code, a thermostat count code, a status code, a temperature set code, and a parity or check sum code. If there was more than one type of master controller response, a response "type code" may also be included. VI. Conclusion In conclusion, it is to be understood that the present invention is not to be limited to that precisely as described hereinabove and as shown in the accompanying drawings. More specifically, the exterior frame 32 may be a molded unit, the side units 38 of the exterior frame 32 may be made of extruded metal, the power assembly 81 may be replaced by alkaline or nicad batteries, the thermostat units 50 may be hardwired to the central controller 60, the central controller 60 may have a programmable key pad, or the buttons in the thermostat 50 and master controller 70 could be replaced by other known forms of display and control. A simplified system could combine the master 70 and central 60 controllers. Further, the electrical circuits show preferred implementations, but the described functions may be accomplished by other equivalent circuity. The system may also be operated in an "AUTO" mode in which the system recognizes needs for heating and cooling and automatically may switch between heating and cooling modes of operation. Also a master controller may be combined with a zone thermostat. Accordingly, the present invention is not limited to the arrangements precisely as shown and described hereinabove.	A retrofittable heating and air conditioning system for a single family dwelling including a heater and air conditioning furnace system connected to individual zones of a building by a series of output ducts. Each opening of a duct to an individual zone may have a unique, fully sealing, controllable output register assembly. Also, in each zone is a thermostat for sensing the zone temperature and for providing a means for the user to control the temperature of that zone. The system further includes a master controller with such temperature controlling features as a universal zone controller, individual zone controllers, and a timer. Finally, the system includes a central controller for controlling the register assemblies and the air conditioning, heating, and fan with respect to instructions set by the individual zone registers and the master controller.	4
BACKGROUND OF THE INVENTION The present invention pertains to a device for positioning and applying tension to a workpiece, such as trouser fabric during advancement thereof to the stitching instrumentalities of a sewing unit. A well known and common form of sewing unit is that of table-like structure having a sewing or work surface with a sewing machine mounted adjacent one end of said surface. The sewing machine includes the usual stitching and feeding elements, and the unit is provided with one or more tensioning devices defining traveling grippers having movable jaws for gripping and releasing the workpiece in timed sequence with the sewing cycle. The grippers are attached to cable-like elements that are effective in holding the workpiece taut and for returning said grippers to their starting position upon completion of the sewing cycle. The grippers also include adjustable positioning members mounted on the work surface for locating said grippers in their starting positions. The cable-like elements connected to the grippers are adapted to extend through central openings in the positioning members and their opposite ends are attached to counter-weights which serve to return said grippers to their starting positions upon release from the workpiece. The tension device is operatively associated with a feeder device of known type, and is adapted to locate a workpiece in a predetermined location for attachment of the grippers thereto upon their return to their respective positioning members located in starting position. The ability to continuously locate a gripper or grippers in the same starting position relative to the length of a workpiece to be gripped thereby presents a serious problem with tension devices that are adapted to move unrestricted with a workpiece along the work surface. Locating devices are available for the known types of sewing units and are effective in orienting the traveling grippers, upon return to their positioning members, to a position for engaging the next workpiece prior to commencement of another stitching cycle. These locating devices are considered rather complex, require a large number of interconnected elements to accomplish their intended function, and require separate and costly electro-pneumatic control circuits for their operation. In the case of an additional tensioning device for gripping the workpiece intermediate the ends thereof, utilization of the available locating devices would be practically impossible due to the great number of additional interconnected elements that would be required. Additionally, difficulty would be encountered in attempting to interconnect its operating circuit with that of the end tensioning device for the sequence of operation of both devices differ within the range of the total operating cycle of the sewing unit. An object of the present invention is to provide a traveling gripper positioning device for sewing units which is of simplified construction, inexpensive to manufacture and which will consistently and accurately perform its intended function. A more specific object is that of providing a positioning device for an intermediate traveling gripper which is capable of functioning independently of and without operatively interfering with the positioning device for the gripper which holds the end of a workpiece. The technical problem to be solved in order to achieve the above-mentioned objects is that of eliminating the electropneumatic controls for the locating devices. The solution to this technical problem is accomplished by means of gripper return devices which upon return of a gripper to its starting position, is effective in causing pivotal movement of said gripper which orients it to a predetermined position and in readiness for attachment to the next workpiece. SUMMARY OF THE INVENTION Specifically, the present invention pertains to traveling type grippers for applying tension to a workpiece, such as trouser fabric as the latter is caused to move along the work surface to a sewing machine of a sewing unit. Return devices connected to the grippers are effective in maintaining the workpiece taut as it is advanced to the stitching instrumentalities and upon completion of the stitching cycle are effective in returning said grippers to positioning devices in their starting positions. The gripper is interconnected to the return device by means of a cable which is adapted to slide freely through a central opening provided in said gripper's positioning device. The positioning device includes a pair of divergent tongues for receiving the gripper therebetween upon its return to starting position. The cable is attached to the gripper adjacent one end thereof and at a point that is displaced, relative to the longitudinal axis of the gripper, and that portion of the fabric adapted to be held by said gripper. This displacement of the point of attachment of the cable relative to the longitudinal axis of the gripper is effective in causing pivotal movement of the latter, after entering its positioning device, which is generated by the force of the return device that is transmitted through the cable when returning said gripper to starting position. These and other features of the present invention will be made apparent from the following detailed description thereof which is provided with reference to the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sewing unit showing the workpiece tensioning device according to the invention applied thereto; FIGS. 2 and 3 are top views of an end tension device and an intermediate tension device respectively, and FIG. 4 is a view in side elevation of a traveling gripper. DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, a fabric sewing unit suitable, for example, for trouser fabrics and the like consists, in general, of a work surface 10 on which a sewing machine 11 is mounted having a conventional type of work guide 12, a presser foot 13, and a needle 14 all of which function in a known manner with well known stitching and feed elements (not shown). Adjacent the end of the work surface 10 opposite that where the sewing machine 11 is mounted an end tension device generally indicated by numeral 15 is provided (FIGS. 1 and 2) which includes a gripper 16, an adjustable positioning member 17, and a cable element 18 that is slidable and threaded through a central opening provided in the adjustable positioning member 17. One end of the cable element 18 is attached adjacent to one side of the gripper 16 and extending through the positioning member 17 the opposite end is operatively associated with a return device 19 that consists of interchangeable counter-weights that are located beneath the work surface 10. The work surface 10 is provided with an opening 20 through which the cable 18 passes and being in vertical alignment with the counter-weights it serves to facilitate movement of said cable. The gripper 16 serves to grip the trailing end of two superimposed lengths of fabric that form the workpiece 21 to be stitched and must be maintained in alignment one with the other so as to be properly joined during the stitching cycle. The gripper 16, as best shown in FIG. 4 is provided with a lower planar surface 22 which engages the work surfaces 10 and on which it is adapted to slide unrestricted during the performance of said gripper's intended function. The gripper also includes a pivotable jaw 23 that has a pin 24 which is adapted to penetrate the workpiece 21 which when held by said gripper is located intermediate the planar surface 22 and said jaw 23. In order to maintain a firm grip on the workpiece the jaw 23 is provided with a resilient plate 25, the function of which is to press said fabric against the upper side of the planar surface 22. The pivotable jaw 23 is closed by manually pushing downwardly on a knob 26 that forms a part of said jaw so as to engage a locking device (not shown). To automatically open the jaw, the latter includes a generally vertically extending level 27 which is adapted to be engaged and pivoted by a horizontal rod 28 that is disposed adjacent the sewing machine 11. When the gripper 16, drawn by the workpiece 21 approaches the sewing machine 11, the lever 27 is pivoted by the horizontal rod 28 and causes release of the above-mentioned locking device and the opening of the pivotable jaw 23 so as to release the workpiece held thereby. Under the action of the return device 19, the gripper 16 is drawn by the cable 18 toward the positioning member 17. The positioning member 17 is adjustably mounted on a rod 29 that is mounted in and extends from a support block 30. This support block is adjustably mounted on a side rail 31 which is attached to and extends along one side of the work surface 10. The side rail 31 serves to locate the support block 30 and consequently the positioning member 17 relative to the location of the sewing machine 11 and the length of the layers of fabric placed therebetween at the start of a stitching cycle. The positioning member 17 includes a pair of divergent tongues 32 and 33 which are disposed so as to receive the gripper 16 when it returns after having released the workpiece 21. Specifically, the tongue identified by numeral 32 extends generally in the same direction of movement as the fabric, whereas the tongue identified by numeral 33 extends in the direction of a feeder device 34 that is positioned on the work surface 10 by means of a rod 29. The feeder device 34 is of a well known type and enables an operator to consistently locate the layers of fabric to be joined in the same predetermined position for permitting attachment of the gripper thereto and serves to substantially reduce the time required for preparing fabrics for stitching. To attach the gripper to the layers of fabric positioned by the feeder device, the gripper on return to the positoning member must be pivoted toward said feeder device and into a recess 35 provided therein so as to locate the pin 24 of said gripper in vertical alignment with that portion of said layers of fabric it will be caused to penetrate. The gripper 16 is pivoted by means of the cable element 18 which is attached to the planar surface 22 at a location identified by numeral 36 in FIG. 2 and which is displaced from the longitudinal axis 37 of said gripper on that side of the latter adjacent the feeder device 34. Pivotal movement of the gripper 16 is accomplished by means of a shock absorber 38 located intermediate the inner ends of the divergent tongues 32 and 33 which is adapted to be engaged by the rearward end of said gripper on its return to starting position and provides a surface about which said gripper is caused to pivot under the influence of the forces developed by the cable element 18 when acted upon by the return device 19. A cessation of pivotal movement of the gripper 16 is had when it engages the tongue 33 which is effective in locating said gripper in the required position for attachment to the next workpiece. When layers of fabric are joined that are very long and that have irregular outlines that extend outwardly beyond the imaginary line that interconnects the end tension device 15 with the presser foot 13, along which line maximum tension is developed on the fabric, an intermediate tension device generally indicated by numeral 39 (FIGS. 1 and 3) is provided. This device serves to grip the workpiece 21 intermediate the ends thereof and maintains the areas having irregular outlines flat on the work surface which without said device would bunch up during movement along said work surface due to the tension applied by the end tension device 15. The intermediate tension device 39, as shown in FIG. 3, includes a gripper 40 that is identical to the gripper 16 and an adjustable positioning member 41 having a pair of divergent tongues 42 and 43 that extend in directions substantially 90° one from the other. More precisely, the tongue identified by numeral 42 is directed toward the sewing machine 11 so that it extends substantially parallel to the direction of movement 44 of the material, whereas the tongue 43 is disposed substantially perpendicular to said direction 44 and to the workpiece 21 to be held by the gripper 40. The gripper 40 is also attached to a cable element that is depicted by numeral 45 and at a location identified by numeral 46 which as with the gripper 16 is displaced from the longitudinal axis 50 of said gripper 40. The gripper 40 also includes a return device which is in the form of counter weights 47 and are effective through cable element 45 in returning said gripper 40 to its positioning member 41 that is provided with a shock absorber 48 disposed intermediate the inner ends of the divergent tongues 42 and 43. As soon as the trailing end of the gripper 40 engages the shock absorber 48 on its return movement, it immediately is caused to pivot in the direction of the tongue 43. Upon engagement of the gripper 40 with the tongue 43 said gripper is automatically located in the desired position for attachment to the next workpiece. The positioning member 41 also includes a support block that is depicted by numeral 49 which like support block 30 is adjustably mounted on the side rail 31 so as to permit selective positioning of said positioning member 41 on the work surface 10. Although the present invention has been described in connection with a preferred embodiment, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and the appended claims.	A positioning device for a traveling gripper in a sewing unit having a cable element interconnecting the gripper with a return device for applying tension to a workpiece being advanced to the sewing machine and returning the gripper to its starting position upon release of the workpiece therefrom. The positioning device defines the grippers starting position and includes a pair of divergent tongues for receiving the gripper therebetween. The cable element is attached to the gripper at a location displaced from its longitudinal axis and is effective through its pulling force, in pivoting the gripper when entering the positioning device to a location in readiness for the next stitching cycle.	3
CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of PCT/PL2009/000081, filed on Aug. 13, 2009, which claims priority to PL Application No. PL385908, filed on Aug. 19, 2008, the contents of each being incorporated herein by reference. FIELD OF THE INVENTION The invention relates to a process for the preparation of conductive carbon layers on powdered supports, suitable in particular for electrode layers in lithium batteries. BACKGROUND OF THE INVENTION A process for the preparation of carbon layers by pyrolysis of organic compounds or polymers on powdered ceramic supports is known. “ A new method of coating powdered supports with conductive carbon films” (M. Molenda, R. Dziembaj, Z. Piwowarska, M. Drozdek, J. Therm. Anal. Cal., 88, 2007, 503-506) discloses a process for the preparation of conductive carbon layers by pyrolysis of polyacrylonitrile deposited on Al 2 O 3 grains. According to the process, radical polymerization of acrylonitrile in an aqueous Al 2 O 3 suspension was carried out, followed by controlled pyrolysis of the such-obtained precursor, under argon atmosphere, at 400-800° C. for 12 h. Similarly, pyrolysis of poly(N-vinylformamide) (PNVF) deposited on powdered Al 2 O 3 by wet impregnation from an aqueous solution was performed in “ Direct Preparation of Conductive Carbon Layer ( CCL ) on Alumina as a Model System for Direct Preparation of Carbon Coated Particles of the Composite Li - Ion Electrodes” (M. Molenda, R. Dziembaj, M. Drozdek, E. Podstawka, L. M. Proniewicz, Solid State Ionics 179, 2008, 197-201). In the case of conductive carbon layers intended for lithium batteries, the layers should be characterized by sufficient electrical conductivity, as well as easy transport of lithium ions through the layer during charging and discharging. At the same time, they should exhibit possibly low contact surface area with an electrolyte to suppress formation of a SEI (Solid-Electrolite Interphase) layer. Electrical properties of a carbon layer are improved with increase of pyrolysis temperature, however given limited thermal stability of electrode materials in reductive conditions it is required that the pyrolysis process is carried out at the lowest temperature possible. Carbon layers obtained by pyrolysis of a PNVF precursor did not exhibit sufficiently high electrical conductivity and possessed a high specific surface area. The process for the preparation of carbon layers on powdered supports comprises dissolving hydrophilic polymer (PH) at a level of 85 to 99.9% by weight in water, adding pyromellitic acid (PMA) or pyromellitic dianhydride (PMDA) at a level of 0.1-15% by weight, followed by adding to the mixture a powdered support at a level of 1-99% by weight. The suspension is concentrated and dried, and then the prepared composite precursor is subjected to pyrolysis at 300-1500° C. Preferably, the hydrophilic polymer is poly(N-vinylformamide), polyacrylamide or N-vinylformamide-acrylamide copolymers Preferably, the powdered support comprises metal oxides, lithium and transition metal silicates and polysilicates, lithium and transition metal phosphates and polyphosphates, germanates, vanadates, metals and metal alloys, metal nitrides and silicon. Most preferably, the powdered support comprises Al 2 O 3 , LiMn 2 O 4 , Li 1-x Mn 2-2x O 4 (0≦x≦0.33), LiMn 2 O 4-y S y (0≦y≦0.25), LiFePO 4 , LiM x Fe 1-x PO 4 (M=V, Mn, Co, Ni, Cu; 0≦x≦1), Li 2 MSiO 4 (M=V, Mn, Fe, Co, Ni, Cu), LiMSiO 4 (M=V, Mn, Fe, Co, Ni, Cu), LiCoO 2 , LiM x CO 1-x O 2 (M=V, Fe, Co, Ni, Cu; 0≦x≦1), LiMn 1/3 CO 1/3 Ni 1/3 O 2 , Sn, SnO, SnO 2 , tin alloys, Si. Preferably, the pyrolysis is carried out in inert conditions, preferably under inert gas atmosphere, most preferably argon, nitrogen or helium atmosphere. Preferably, the pyrolysis is carried out in weakly reducing conditions. Preferably, the pyrolysis is carried out under vacuum. In the process of the invention, it was unexpectedly found that adding pyromellitic acid (PMA) or pyromellitic dianhydride (PMDA) to the hydrophilic polymer composition significantly enhances electrical properties of prepared carbon layers and at the same time allows decreasing temperature of the pyrolysis process. DESCRIPTION OF THE INVENTION In the process of the invention, pyromellitic acid or the anhydride thereof takes the role of a promoter which structuralizes graphitization of the polymer during pyrolysis, rather than being a layer-making factor—its pyrolysis does not lead to obtaining a carbonizate, but decomposition is complete. The planar structure of the molecule of pyromellitic acid or an anhydride thereof accelerates seeding and forming graphene layers, which facilitate two-dimensional crystallization of a graphite-like material. Additionally, pyromellitic acid or the anhydride thereof is thought to facilitate organization of hydrophilic polymer on the surface of the powdered support already at the impregnation step. It was unexpectedly found that the carbon layers originating from pyrolysis of the hydrophilic polymer composition with PMA or PMDA are closely adjacent and tightly cover grains of the support. At the same time the layers are not continuous by nature, having mesopores of a mean size of about 32-35 Å. Such modification of the carbon layer of the composite is particularly beneficial when employed as electrode layers in lithium batteries, since it protects well cathode material against reaction with the electrolyte and simultaneously secures unhampered diffusion of lithium ions through mesopores of the carbon layer. In the process of the invention the composition of a carbon precursor (the water-soluble hydrophilic polymer) with a promoter which structuralizes graphitization of the polymer (PMA or PMDA) allows obtaining of the carbon layer with very good dispersion of carbon material and expected physicochemical properties, such as thickness, tightness and porosity. In particular, suitable electrical conductivity (>10 −4 Scm −1 ) of the carbon layer prepared at above 400° C. can be obtained in the process. Preferably the process proceeds entirely in aqueous environment and the precursors employed are non-toxic, which makes the technology safe and environmentally friendly. The process of the invention can be employed for obtaining electrode composites (both cathodes and anodes) for lithium batteries. Electrode composites produced by the process of the invention are characterized by better electrical properties and increased chemical stability, that improves operational safety of lithium batteries. The process of the invention can also be employed for preparing composite adsorbents of defined surface morphology obtained from suitable inorganic supports. The subject-matter of the invention is described in more detail in the following working examples. EXAMPLE 1 10 g of freshly distilled N-vinylformamide (98%) was dissolved in 66 g of deionized water pre-treated with argon for about 30 minutes. The reaction was placed on a water bath and warmed to 35° C. under argon atmosphere. 1.9092 g of AIBA initiator (2,2′-azobis(2-methylpropionamidinyl) dichloride) was then added and the reaction was kept at 60° C. for 2 h. Poly(N-vinylformamide) thus obtained was air-dried for 24 h at 110° C. 0.625 g of dry poly-N-vinylformamide and 0.0329 g pyromellitic acid was dissolved in 12.5 cm 3 of deionized water. 0.375 g LiMn 2 O 3.95 S 0.05 was then added and the contents stirred for 15 minutes. The homogenous mixture formed was kept at 90° C. with continuous stirring for about 2 h to evaporate and concentrate it to a viscosity precluding sedimentation of the suspension. The composite precursor formed was transferred to a teflon container and air-dried for 24 h at 90° C. The dried precursor was crumbled and pyrolyzed at 400° C. under argon atmosphere (99.999%), for 12 h. This yielded a carbon layer characterized by electrical conductivity of 7.4·10 −6 S/cm at 25° C. and electrical conductivity activation energy E a =0.34 eV. Carbon content in the composite determined by TPO method was 27.6%. EXAMPLE 2 0.7 g of dry poly(N-vinylformamide) and 0.04 g of pyromellitic acid were dissolved in 14.1 cm 3 of deionized water. 1.0 g of LiMn 2 O 4 spinel was then added and the mixture stirred for 15 minutes. The homogenous mixture formed was kept at 90° C. with continuous stirring for about 2 h to evaporate and concentrate it to the viscosity precluding sedimentation of the suspension. The composite precursor formed was transferred to a teflon container and air-dried for 24 h at 90° C. The dried precursor was crumbled and pyrolyzed at 400° C., under argon atmosphere (99.999%) for 12 h. This yielded a composite comprised of the LiMn 2 O 4 support coated by a carbon layer, characterized by the electrical conductivity of 3.3·10 −6 S/cm at 25° C. and the electrical conductivity activation energy E a =0.37 eV. Specific surface area of the composite as determined by BET isotherm method was 5.5 m 2 /g, and carbon content in the composite was 20.3% (determined by TPO method). EXAMPLE 3 Comparative 1.87045 g of dry (175° C./24 h) lithium nitrate (V) LiNO 3 was dissolved in 70 cm 3 of deionized water in a sealed glass vessel under the stream of argon (99.999%, 20 dm 3 /h). 13.25465 g of manganese (II) acetate hydrate Mn(CH 3 COO) 2 ·4H 2 O (Aldrich 99.99%) was added to the solution. Once the substrates dissolved, 10 ml of 25% NH 3 aq was added dropwise until pH=10 was reached. The salmon-colored mixture (a sol) was left to condense for 24 h with continuous stirring and heating at about 100° C. in argon atmosphere (99.999%, 20 dm 3 /h). The gel formed was transferred to a melting pot and air-dried at 90° C. for 48 h. The dried xerogel precursor was crumbled and air-calcined at 300° C. (with heating rate of 1° C./min) for 24 h, followed by 6 h at 650° C. (with heating rate of 5° C./min). The LiMn 2 O 4 spinel obtained was characterized by electrical conductivity of 1.2·10 −4 S/cm at 25° C. and electrical conductivity activation energy E a =0.34 eV. Specific surface area of the spinel as determined by BET isotherm method was 6.1 m 2 /g. EXAMPLE 4 0.8084 g of dry poly(N-vinylformamide) prepared as in Example 1 and 0.0365 g of pyromellitic dianhydride were dissolved in 10 cm 3 of deionized water. 1 g of Al 2 O 3 was then added and the mixture stirred for 30 minutes. The homogenous mixture formed was kept at 90° C. with continuous stirring for about 3 h to evaporate and concentrate it to a viscosity precluding sedimentation of the suspension. The composite precursor formed was transferred to a teflon container and air-dried for 24 h at 90° C. The dried precursor was crumbled and pyrolyzed at 550° C. in argon atmosphere (99.999%), for 6 h. This yielded a carbon layer characterized by electrical conductivity of 8.1·10 −4 S/cm at 25° C. Carbon content in the composite determined by TPO method was 13.5%. EXAMPLE 5 Example 1 was followed, with corresponding change of parameters for the following samples: 5/1—1.002 g of the LiMn 2 O 4 support, 0.9 g of PNVF, 0.0475 of PMA, 18 cm 3 of H 2 O, 6 h pyrolysis time 5/2—1.001 g of the LiMn 2 O 4 support 1.001 of g PNVF, 0.0527 of PMA, 20 cm 3 of H 2 O, 6 h pyrolysis time 5/3—0.75 g of the LiMn 2 O 4 support, 1,2501 g of PNVF, 0,0658 of PMA, 25 cm 3 of H 2 O, 6 h pyrolysis time 5/4—0.5 g of the LiMn 2 O 3.97 S 0.03 support, 0.45 g of PNVF, 0.02375 of PMA, 9 cm 3 of H 2 O, 12 h pyrolysis time 5/5—0.375 g of the LiMn 2 O 3.97 S 0.03 support, 0.62505 g of PNVF, 0.0329 of PMA, 12.5 cm 3 of H 2 O, 6 h pyrolysis time 5/6—0.5 g of the LiMn 2 O 3.95 S 0.05 support, 0.45 g of PNVF, 0.02375 of PMA, 9 cm 3 of H 2 O, 12 h pyrolysis time 5/7—0.5 g of the LiMn 2 O 39 S o1 support, 0.45 g of PNVF, 0.02375 of PMA, 9 cm 3 of H 2 O, 12 h pyrolysis time 5/8—0.375 g of the LiMn 2 O 3.9 S 0.1 support, 0.625 g of PNVF, 0.03289 of PMA, 12.5 cm 3 of H 2 O, 12 h pyrolysis time For materials of the C/Li—Mn—O—S type prepared according to Example 1 and Example 4, carbon content and surface morphology were estimated and studied. The estimated carbon content was determined based on pyrolysis of a 11% PMA and 89% PNVF precursor not deposited on a support. The actual carbon content was determined by temperature-programmed TPO oxidation, as disclosed in “ A new method of coating powdered supports with conductive carbon films” (M. Molenda, R. Dziembaj, Z. Piwowarska, M. Drozdek, J. Therm. Anal. Cal., 88, 2007, 503-506). The determination was made with EGA-TGA/DTG/SDTA techniques on Mettler-Toledo 851 e thermoanalyzer coupled with Thermostar Balzers quadrupole spectrometer. The measurements were performed in the air stream of 80 ml/min at the temperature range of 30-1000° C. with a heating rate of 5° C./min. The surface morphology was studied by BET isotherm method. Specific surface area measurements were carried out under the pressure of 5.7·10 −7 Pa on Micrometrics ASAP 2010 sorptiometer. The samples were degassed at 200-250° C. for 2 h under the pressure of 0.260.4 Pa. The results obtained are presented in Table 1. TABLE 1 Sample Estimated Actual BET max. Pore distribution according carbon carbon surface pore mean pore to content content area diameter size Example [%] [%] [m 2 /g] [Å] [Å] 2 14.3 20.3 5.5 123 34.1 and 51 5/1 18.7 23.4 8.5 140 32.7 5/2 27.1 24.2 8.9 120 35.0 5/3 30.4 33.9 7.4 130 34.8 5/4 19.4 18.6 10.2 100 33.5 5/5 28.0 32.5 12.5 89 32.9 5/6 19.0 21.1 9.1 127 33.1 5/7 20.2 19.8 9.6 105 33.8 5/8 28.4 30.5 8.4 112 33.9 3 — — 6.1 174 200 The actual carbon content was greater than the estimated amount for all composites. This can prove a beneficial influence of pyromellitic acid or pyromellitic dianhydride on pyrolysis mechanism of the precursor deposited on support grains. The increase of carbon percentage on the support surface enhances its dispersion without local aggregation. Characteristics of the obtained adsorption isotherms suggests the presence of pores in the form of microcracks and inter-grain splits. At the same time, pore size indicates the presence of mesopores of the very narrow and uniform diameter distribution in the range of 32-35 Å.	A process for the preparation of carbon layers on powdered supports comprising dissolving a hydrophilic polymer (PH) at the level of 85 do 99.9% by weight in water, adding pyromellitic acid (PMA) or pyromellitic dianhydride (PMDA) at the level of 0.1-15% by weight, then introducing to the mixture the powdered support at a level of 1-99% by weight. The suspension is concentrated and dried, and the composite precursor formed is subjected to a pyrolysis process at 300-1500° C.	2
FIELD OF THE INVENTION This invention relates to pharmaceutical compositions with increased hypotensive effects as well as to a process for the preparation thereof. BACKGROUND OF THE INVENTION Compounds which exert a blocking effect on β-adrenergic receptors are have found increasingly widespread acceptance in the treatment of hypertension (Knoll J.: Gyogyszertan, Medicina, p. 282, 1971); S. Wolfson: Drugs in Cardiology Vol. I, pp. 165-179, (Stratton Intercont. Med. Book Corp., New York, 1975; R. P. Ahlquist: Progress in Drug Research 20, pp. 27-42, (Birkhauser Verlag, Basel, 1976). Their use is, however, restricted by several contraindications, such as respiratory disease (bronchial asthma), cardiovascular disease (bradycardia, heart block), renal inflammation and metabolic disorder, e.g. diabetes mellitus and liver disease (R. P. Ahlquist: Beta-Adrenergic Blocking Agents in the Management of Hypertension and Angina Pectoris, pp. 1-81, Raven Press, New York, 1974). The dosages required in the treatment of hypertension are 4 to 8 times higher than those provoking antiarrhythmic effects (A. Ablad: Drugs, 11, Suppl. 1, pp. 127-134, 1976), which may give rise to the appearance of more severe side effects, such as bronchial spasms, cardiac disorders, central nervous-system effects (hallucinations, insomnia, depression), Raynaud-syndrome and gastrointestinal disorders (D. J. Greenblatt: Drugs, 7, 118, 1974; S. A. Stephen: Am. J. Cardiol. 18, 463, 1966). A further characteristic feature of β-receptor blocking agents is that, beyond a certain limit, their therapeutic effect cannot be incresed by increasing the dosage (P. Kincaid-Smith: Beta-Adrenergic Blocking Agents in the Management of Hypertension and Angina Pectoris, pp. 9-19 (Raven Press, New York, (1974). OBJECT OF THE INVENTION The invention has the object of providing a novel pharmaceutical composition, free from the disadvantages discussed above, which exerts beneficial therapeutic effects in much lower dosages than the hitherto known ones and causes much weaker undesired side effects, if any, than conventional β-receptor blocking agents. DESCRIPTION OF THE INVENTION The invention is based on the surprising discovery that compounds of formula (I), below, which, when applied alone, exert a blocking effect on the biosynthesis of noradrenaline (decarboxylase, tyrosine hydroxylase and dopamine-β-hydroxylase blocking effects, see Zs. Huszti: Biochem. Pharm. 22, 2253 (1973) and Belgian Pat. No. 868,027), considerably potentiate the hypotensive effect of the β-adrenergic receptor blocking agents having formula (V), infra. Based on the above, the invention provides pharmaceutical compositions with increased hypotensive effects, comprising a compound of formula (I), ##STR6## wherein R 1 is a group of formula (II), ##STR7## (wherein R 4 and R 5 each can be hydrogen, hydroxy, nitro or C 1-4 alkoxycarbonyl), and at the same time R 2 and R 3 are each hydrogen, or R 1 is 3-chloro-6-pyridazinylamino, 3-methyl-6-pyridazinylamino or 3-carbamoyl-6-pyridazinylamino group, and at the same time R 2 and R 3 form together a group of formula (III), ##STR8## wherein R 6 is C 1-4 alkyl, R 7 is hydrogen or C 1-4 alkyl, and n is an integer of 1 to 3, or R 2 and R 3 form together a group of formula (IV), =Q-R.sup.8 (IV) wherein Q is C 5-7 cycloaliphatic group, and R 8 is hydrogen, C 1-4 alkoxycarbonyl or C 2-4 alkyl, and a compound of formula (V) or a salt thereof, ##STR9## wherein R 9 is naphthyl, 4-indolyl or 4-morpholino-1,2,5-thiadiazol-3-yl group or a group of formula (VI), ##STR10## wherein R 11 , R 12 and R 13 are the same or different and represent hydrogen, halogen, hydroxy, C 1-4 alkyl, C 1-4 alkoxy, C 2-4 alkenyloxy, 2-methoxyethyl or acetic amide, with the proviso that when two of R 11 , R 12 and R 13 are hydrogen, the third substituent is other than hydrogen, and when two of R 11 , R 12 and R 13 are acetic amide, the third substituent is other than acetic amide, and R 10 stands for C 1-4 alkyl, in admixture with one or more conventional pharmaceutical additives. The invention relates further to a process for the preparation of novel pharmaceutical compositions with increased hypotensive effects. According to the invention a compoun of formula (I) is admixed with a compound of formula (V) and the mixture is converted into pharmaceutical dosage forms, such as tablets, suppositories, etc., utilizing conventional pharmaceutical additives. A preferred pharmaceutical composition according to the invention comprises 1 part by weight of 1-(4-indolyloxy)-3-isopropylamino-2-propanol hydrochloride (further: pindolol) in admixture with 20 parts by weight of 3-hydroxy-4-nitro-benzyloxyamine hydrochloride (further: compound 11,130). Another preferred composition comprises 1 part by weight of pindolol in admixture with 40 parts by weight of 2-hydroxy-5-carbomethoxy-benzyloxyamine hydrochloride (further: compound 11,121). Other preferred compositions according to the invention contain as β-adrenergic receptor blocking agent a compound listed in Table 1, together with a noradrenaline biosynthesis blocking compound as listed in Table 2 or a salt thereof. TABLE 1______________________________________ International nameChemical name or protected name______________________________________1-(1-Naphthyloxy)-3-isopropylamino- Propranolol2-propanol hydrochloride1-(2,5-Dichlorophenoxy)-3-tert.-butyl- Tobanumamino-2-propanol hydrochloride1-(4-[2-Methoxyethyl]-phenoxy)-3-iso- Metoprololpropylamino-2-propanol hydrochloride1-(4-Aminocarbonylmethyl-phenoxy)-3-iso- Atenololpropylamino-2-propanol hydrochloride1-(2-Allyloxy-phenoxy)-3-isopropyl- Oxprenololamino-2-propanol hydrochloride______________________________________ TABLE 2______________________________________ Code No.Chemical name (Compound)______________________________________N.sup.1 -(3-Chloro-6-pyridazinyl)-N.sup.2 -(1-carbethoxy- 11,4732-propylidene)-hydrazineN.sup.1 -(3-Chloro-6-pyridazinyl)-N.sup.2 -(1-carbethoxy- 11,5112-cyclohexylidene)-hydrazineN.sup.1 -(3-Chloro-6-pyridazinyl)-N.sup.2 -(2,2-methyl- 11,5881-cyclohexylidene)-hydrazineN.sup.1 -(3-chloro-6-pyridazinyl)-N.sup.2 -(1-tert.- 11,653carbobutoxy-2-propylidene)-hydrazineN.sup.1 -(3-Carbamoyl-6-pyridazinyl)N.sup.2 -(1-tert.- 11,702carbobutoxy-2-propylidene)-hydrazineN.sup.1 -(3-Methyl-6-pyridazinyl)-N.sup.2 -(1-tert.- 11,741carbobutoxy-2-propylidene)-hydrazine______________________________________ The compositions according to the invention contain the β-receptor blocking agents in lower dosages than the conventional dosage, thus the undesired side effects of these compounds can be suppressed considerably. Another advantage of the new compositions is that the noradrenaline biosynthesis blocking compounds applied potentiate the hypotensive effects of the β-receptor blocking agents, i.e. the hypotensive effect of the composition greatly exceeds the algebraic sum of the activities of the individual constituents. The favorable effects of the new hypotensive compositions according to the invention are demonostrated by the pharmaceutical test results described below. (1) Determination of the hypotensive effect on awake rats suffering from genetic hypertension The tests were performed according to the method of Eaton (J. C. R. Eaton: Brit. J. Pharm. 54, 282 (1975) with the modification that the blood pressure and cardiac frequency of Wistar-Okamoto rats were measured with an automatic five-channel instrument. The compounds and dosages applied, as well as the test results are listed in Tables 3 to 6. The data of Tables 3 to 5 demonstrate the beneficial results obtained by administering pindolol in combination with a noradrenaline biosynthesis blocking agent. TABLE 3______________________________________Effect of pindolol, compound 11,130 and combinations thereof onthe blood pressure of genetically hypertensive awake rats Blood pressure (mm Hg) Dosage AfterCom- mg/kg No. of Basal After After 24pound p.o. animals value 2 hours 5 hours hours______________________________________Pindolol 0.25 10 182.2 180.8 164.9 183.4 ±23.4 ±48.2 ±28.7 ±46.2Pindolol 0.25 5 161.0 140.0* 146.0 153.011,130 20 ±10.8 ±11.7 ±12.4 ±20.8Pindolol 0.5 15 165.0 161.4 160.5 150.5 ±14.2 ±18.6 ±22.2 ±22.4Pindolol 0.5 15 173.2 128.2** 123.6 159.311,130 20 ±17.6 ±34.7 ±24.1 ±26.2Pindolol 1.0 10 164.4 135.0* 135.0* 151.1 ±13.8 ±20.5 ±16.9 ±22.2Pindolol 5.0 10 172.5 154.5* 124.5**** 161.0 ±14.4 ±8.0 ±15.0 ±20.511,130 20 5 174.0 183.0 176.0 172.0 ±12.9 ±18.2 ±10.2 ±14.4______________________________________ * = 0.05 > p > 0.02 = 0.02 > p > 0.01 * = 0.01 > p > 0.001 ** = 0.001 > p p = statistical significance (R.A. Fisher: "Statistical Methods for Research Workers", Oliver and Boyd, London, 1950) ED.sub.30% p.o. ˜ 5 mg/kg of pindolol ED.sub.30% p.o. ˜ 0.5 mg/kg of pindolol + 20 mg/kg of 11,130 (ED.sub.30% is the dosage which decreases the blood pressure by 30% related to the value before treatment) The test results listed in Table 3 indicate that the ED 30% of pindolol (5 mg/kg) can be decreased to one-tenth upon combining this compound with 11,130. TABLE 4______________________________________Effect of pindolol, 11,121 and combinations thereof on theblood pressure of genetically hypertensive awake rats Blood pressure (mmHg) Dosage AfterCom- mg/kg No. of Basal After After 24pound p.o. animals value 2 hours 5 hours hours______________________________________Pindolol 0.25 10 184.4 181.6 168.8 188.8 ±29.4 ±28.8 ±18.9 ±46.8Pindolol 0.25 10 199.4 151.7 178.8 183.311,121 5 ±41.7 ±26.3 ±49.2 ±40.3Pindolol 0.25 10 182.2 165.0 138.9*** 175.011,121 10 ±26 ±28.3 ±23.2 ±9.7Pindolol 0.5 10 200.0 191.2 188.3 188.9 ±31.8 ±7.9 ±36.4 ±38.4Pindolol 0.5 10 208.7 156.7* 150.4 192.911,121 5 ±40.1 ±48.8 ±44.0 ±51.7Pindolol 0.5 10 160.5 112.2* 112.7* 146.711,121 20 ±21.1 ±32.1 ±23.7 ±24.4Pindolol 1 10 164.4 135.0* 135.0* 151.1 ±13.8 ±20.5 ±16.9 ±22.2Pindolol 5 10 172.5 154.5* 124.5**** 161.0 ±14.4 ±8.0 ±15.0 ±20.511,121 50 5 168.2 170.0 163.0 169.0 ±10.4 ±11.2 ±17.8 ±13.4______________________________________ * = 0.05 > p > 0.02 = 0.02 > p > 0.01 * = 0.01 > p > 0.001 **** = 0.001 > p ED.sub.30% p.o. ˜ 5 mg/kg of pindolol ED.sub.30% p.o. ˜ 0.5 mg/kg of pindolol + 20 mg/kg of 11,121 The test results listed in Table 4 indicate that the combined administration of 11,121 and pindolol causes an approximately tenfold increase in the activity of pindolol. Thus the combinations of these compounds can be applied to advantage in therapy. TABLE 5______________________________________Effect of pindolol, 11,473 and combinations thereof on theblood pressure of genetically hypertensive awake rats Blood pressure (mmHg) Dosage AfterCom- mg/kg No. of Basal After After 24pound p.o. animals value 2 hours 5 hours hours______________________________________Pindolol 0.5 15 200.3 172.1* 160.8* 188.6 ±30.5 ±36.9 ±46.9 ±30.2Pindolol 0.5 15 196.0 159.6 141.3 179.911,473 5 ±35.3 ±33.5 ±48.3 ±28.1Pindolol 0.5 15 205.3 149.3* 138.2 191.311,473 10 ±23.3 ±40.1 ±32.9 ±42Pindolol 1 10 164.4 135.0* 135.0* 151.1 ±13.8 ±20.5 ±16.9 ±22.2Pindolol 5 10 172.5 154.5* 124.5**** 161.0 ±14.4 ±8.0 ±15.0 ±20.511,473 10 5 195.0 194.0 197.0 198.0 ±11.2 ±8.2 ±7.6 ±9.1______________________________________ * = 0.05 > p > 0.02 = 0.02 > p > 0.01 * = 0.01 > p > 0.001 **** = 0.001 > p ED.sub.30% p.o. ˜ 5 mg/kg of pindolol ED.sub.30% p.o. ˜ 0.5 mg/kg of pindolol + 10 mg/kg of 11,473 The test results listed in Table 5 indicate that the required dosage of pindolol can be decreased to about one tenth by administering it in combination with 11,473. Thus the combinations of these compounds can be applied to advantage in therapy. The hypotensive effect of propranolol can also be increased by combining it with a noradrenaline biosynthesis blocking agent, such as 11,130. The test results are given in Table 6. TABLE 6______________________________________Effect of propranolol, 11,130 and combinations thereof onthe blood pressure of genetically hypertensive awake rats Blood pressure (mmHg) Dosage After mg/kg No. of Basal After After 24Compound p.o. animals value 2 hours 5 hours hours______________________________________Propranolol 1 5 167.5 170.0 168.7 157.5 ±12.6 ±12.9 ±13.8 ±8.7Propranolol 1 15 169.5 161.9 146.1* 163.911,130 20 ±21.0 ±26.0 ±19.7 ±23.1Propranolol 5 10 186.4 178.6 175.9 181.8 ±13.6 ±13.4 ±24.3 ±16.8Propranolol 10 15 178.0 170.0 148.3* 163.7 ±16.1 ±15.2 ±18.6 ±24.711,130 20 5 174.0 183.0 176.0 172.0 ±12.9 ±18.2 ±10.2 ±14.4______________________________________ * = 0.001 > p ED.sub.15% p.o. ˜ 10 mg/kg of propranolol ED.sub.15% p.o. ˜ 1 mg/kg of propranolol + 20 mg/kg of 11,130 The test results listed in Table 6 indicate that the combined administration of propranolol and 11,130 causes an about tenfold increase in the activity of the β-receptor blocking component. (2) Determination of the hypotensive effect on awake dogs suffering from renal hypertension The tests were performed on dogs suffering from renal hypertension, subjected to operation as described by Grollman (A. Grollman: Proc. Soc. Exp. Biol. Med. 57, 102 (1944). The effects were determined by measuring the blood pressure on the caudal artery and the pulse rate. The test results obtained with pindolol, 11,121 and a combination thereof are listed in Table 7. The data of Table 7 indicate that the hypotensive character of pindolol also changes favorably when using dogs as test animals. TABLE 7__________________________________________________________________________Effect of pindolol, 11,121 and a combination thereof on the bloodpressure of awake dogswith renal hypertensionDosage Blood pressure (mmHg) mg/kg No. of Basal After After After After After AfterCompound p.o. animals value 1 hour 2 hours 3 hours 4 hours 5 hours 24 hours__________________________________________________________________________Pindolol 0.1 3 156.7 133.3 133.3 153.0 156.7 160.0 153.3 ±15.3 ±11.5 ±17.6 ±5.8 ±2.9 ±5.0 ±11.511,121 5 3 165.0 170.0 167.5 175.0 165.0 172.5 165.0 ±5.8 ±7.6 ±10.4 ±5.0 ±5.0 ±7.6 ±2.9Pindolol 0.1 4 160.0 130.0 111.2* 143.7 148.7 160.0 157.511,121 5 ±20.9 ±30.8 ±16.5 ±21.4 ±13.1 ±8.2 ±15.5__________________________________________________________________________ * = 0.05 > p > 0.02 (3) Toxicity tests Based on the data given in points 1 and 2 above it can be stated that a considerable potentiating synergism appears with respect to the hypotensive effect when applying the compounds of formula (I) in combination with those of formula (V). In the following it was investigated whether this synergism also appears with respect to the toxicity. In the first test series the LD 50 values of the individual components were determined on CFLP-mice. The compounds were administered orally, and the animals were kept under observation for one week. The LD 50 values of the individual compounds are as follows: Pindolol: LD 50 =300 mg/kg p.o. 11,121: LD 50 =2900 mg/kg p.o. 11,473: LD 50 =360 mg/kg p.o. To determine the toxicity values of the combinations dosages calculated on the basis of the isobole construction principle were applied. The animals were pre-treated for one hour with various dosages of 11,473 or 11,121, and then varying dosages of pindolol were administered. The results are listed in Table 8. The data of Table 8 indicate that a pre-treatment with 100 or 200 mg/kg of 11,473, or with 100 or 1000 mg/kg of 11,121 hardly influences the toxicity of pindolol, thus there is no undesired potentiation of toxicity. TABLE 8______________________________________Toxicity values of pindolol + 11,473 and pindolol + 11,121Mortality (%) 11,121 p.o.Pindolol Pindo- 11,473 p.o. 1000 2000mg/kg lol 100 200 300 100 mg/ mg/p.o. alone mg/kg mg/kg mg/kg mg/kg kg kg______________________________________ 60 0 0 0 50 0 0 30 90 0 0 0 50 0 0 40135 8 0 0 70 0 0 40200 16 20 20 -- 0 10 30300 46 40 70 -- 50 30 40450 75 70 -- -- 80 45 80______________________________________ The test results prove unambiguously that the new combinations according to the invention enable one to use the active agents in lower amounts or in more effective forms with a high security. The invention is elucidated in detail by the aid of the following non-limiting Examples. EXAMPLE 1 Preparation of tablets Composition of one tablet: ______________________________________Pindolol 2.5 mg11,121 100.0 mgMicrocrystalline cellulose 88.5 mgMagnesium stearate 2.0 mgTalc 6.0 mgColloidal silicon dioxide 1.0 mg______________________________________ The tablets, weighing 200 mg in average, are provided with film coating. EXAMPLE 2 Preparation of capsules Composition of one capsule: ______________________________________Pindolol 2.5 mg11,473 100.0 mgTalc 3.0 mgMagnesium stearate 2.0 mgColloidal silicon dioxide 0.5 mg______________________________________ The mixture is filled into self-closing hard gelatine capsules. One capsule contains 108 mg of the above mixture in average. EXAMPLE 3 Preparation of tablets Composition of one tablet: ______________________________________Propranolol 3.0 mg11,653 100.0 mgMicrocrystalline cellulose 88.5 mgMagnesium stearate 2.0 mgTalc 6.0 mgColloidal silicon dioxide 1.0 mg______________________________________ EXAMPLE 4 Preparation of tablets Composition of one tablet: ______________________________________Atenolol 2.5 mg11,702 80.0 mgMicrocrystalline cellulose 80.0 mgMagnesium stearate 2.0 mgTalc 6.0 mgColloidal silicon dioxide 1.0 mg______________________________________	A pharmaceutical compositions with hypotensive effects which comprise a compound of formula (I) or a pharmaceutically acceptable acid addition salt thereof, ##STR1## wherein R 1 is formula (II) ##STR2## wherein R 4 and R 5 each represent hydrogen, hydroxy, nitro at the same time R 2 and R 3 are hydrogen, or R 1 are 3-chloro-6-pyridazinylamino, 3-methyl-6-pyridazinylamino or 3-carbamoyl-6-pyridazinylamino, and at the same time R 2 and R 3 form together formula (III), ##STR3## wherein R 6 is C 1-4 alkyl group, R 7 is hydrogen or a C 1-4 alkyl group, and n is an integer of 1 to 3, or R 2 and R 3 form together a group of the general formula (IV), =Q-R.sup.8 (IV) wherein Q is C 5-7 cycloaliphatic, and R 8 is hydrogen, a C 1-4 alkoxycarbonyl or a C 2-4 alkyl, and a compound of formula (V) or a pharmaceutically acceptable acid addition salt thereof, ##STR4## wherein R 9 is naphthyl, 4-indolyl or 4-morpholino-1,2,5-thiadiazol-3-yl group or ##STR5## .	0
U.S. GOVERNMENT RIGHTS The invention was made with U.S. Government support under contract F33615-95-C-2503 awarded by the U.S. Air Force. The U.S. Government has certain rights in the invention. BACKGROUND OF THE INVENTION This invention relates to engines, and more particularly to hybrid pulse combustion turbine engines. In a conventional gas turbine engine, combustion occurs in a continuous, near constant pressure (Brayton cycle), mode. Although present gas turbine engine combustors are relatively efficient, the thermodynamic benefit to cycle efficiency associated with performing the combustion operation at a higher time-averaged pressure has led to many efforts to improve combustion. It has been proposed to improve thermodynamic efficiency by applying the more efficient combustion of near constant volume combustion pulse detonation engines (PDEs) to turbine engine combustors. In a generalized PDE, fuel and oxidizer (e.g., oxygen-containing gas such as air) are admitted to an elongate combustion chamber at an upstream inlet end, typically through an inlet valve as a mixture. Upon introduction of this charge, the valve is closed and an igniter is utilized to detonate the charge (either directly or through a deflagration to detonation transition). A detonation wave propagates toward the outlet at supersonic speed causing substantial combustion of the fuel/air mixture before the mixture can be substantially driven from the outlet. The result of the combustion is to rapidly elevate pressure within the chamber before substantial gas can escape inertially through the outlet. The effect of this inertial confinement is to produce near constant volume combustion. U.S. Pat. No. 6,442,930, for example, suggests combustor use of PDE technology in addition to use as a thrust augmentor in engines with conventional combustors. Other pulsed combustors are shown in U.S. Pat. Nos. 6,886,325 and 6,901,738. BRIEF SUMMARY OF THE INVENTION One aspect of the invention involves a turbine engine having a case with an axis. A fan is mounted for rotation about the axis. A turbine is mechanically coupled to the fan to drive rotation of the fan about the axis. A number of compressor/turbine units are downstream of the fan and upstream of the turbine along a core flowpath. A number of compressors are coupled to the compressor/turbine units to receive air and deliver combustion gas to drive the turbine. In various implementations, the compressor/turbine units may be centrifugal compressor/radial turbine units, with the turbine coaxially driving the impeller by means of a connecting shaft. There may be a circumferential array of the compressor/turbine units and a circumferential array of the combustors. Each of the compressor/turbine units may be uniquely associated with a single one of the combustors and vice versa. The compressor/turbine units may be coupled to the combustor so that: the compressor of the compressor/turbine unit delivers air to the associated combustor; and the turbine of the compressor/turbine unit receives the combustion gas from the associated combustor. The turbine may be an axial turbine receiving the combustion gas from all of the compressor/turbine units. The axial turbine may be co-spooled with the fan. There may be at least eight of the compressor/turbine units and at least eight of the combustors. The combustors may be non-rotating. Another aspect of the invention involves a method for operating a turbine engine. Air is directed from a fan to a number of compressor/turbine units. The air is compressed in the compressor/turbine units. The air is directed to a number of combustors. The air is combusted with fuel in the combustors to produce combustion gas. Work is extracted from the combustion gas in the compressor/turbine units to drive the compression. The combustion gas is directed from the compressor/turbine units to a turbine. Work is extracted from the combustion gas in the turbine to drive rotation of the fan. In various implementations, the combustion gas may be directed from the turbine to join a bypass flow of air from the fan. A mass flow ratio of the flow of the air delivered to the combustors to the bypass flow may be between 1.1 and 1:3. The combusting may be a pulse combusting. The combusting may comprise detonation. The combusting may comprise operating respective ones of the combustors out of phase with each other. The method may be used in aircraft propulsion. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic partial longitudinal sectional view of a turbofan engine. FIG. 2 is a cutaway view of the engine of FIG. 1 . FIG. 3 is a schematic partial longitudinal sectional view of an alternative engine. FIG. 4 is a front schematic view of a second alternative engine. Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION FIG. 1 shows a turbofan engine 20 having central longitudinal axis 500 , a case 22 , and a core 24 . The case 22 defines a duct 26 extending from an upstream inlet 28 to a downstream outlet 30 . Of an inlet airflow 510 entering the duct, a fan 32 drives a bypass portion 512 and a core portion 514 along respective bypass and core flowpaths through the duct. The exemplary fan 32 has two blade stages and two interspersed vane stages. The blade stages may be supported on a shaft 34 . As is described in further detail below, the exemplary engine 20 also includes a circumferential array of compressor/turbine units 38 , a combustor section 40 (e.g., circumferential array of combustors 41 ), and a turbine section 42 . Other components (e.g., an augmentor and an exhaust nozzle) may also be present. FIG. 2 shows further details of exemplary positions of the exemplary compressor/turbine units 38 and combustors 41 . The core airflow 514 is divided by ducts 44 into branching portions directed to the compressor sections 50 (e.g., centrifugal compressors) of each of the units 38 . Rotation of the impeller of the section 50 is driven by the turbine of the turbine section 52 (e.g., a radial turbine) of the associated unit 38 . The units 38 thus compress the flow 514 into compressed flows 516 directed to the combustor section 40 . In each unit 38 , the compressor section 50 and turbine section 52 are coaxial about an axis non-coincident with the engine axis 500 . In the combustor section 40 , the compressed air is mixed with a fuel flow 518 and combusted to form combustion gas 520 . The gas 520 is directed to the turbine of the turbine section 52 where it is partially expanded to extract the work to compress the flow 514 . From the unit 38 , the partially expanded combustion gas flow 522 is directed to the turbine section 42 . For example, the turbine sections 52 of the various units 38 may be coupled to a common discharge manifold 60 feeding an upstream/inlet end of the turbine section 42 . As the flow 522 passes through the turbine section 42 it is further expanded and discharged as a flow 524 . The exemplary flow 524 is directed via a manifold duct 62 to merge with the bypass flow 512 and form a combined flow 526 . This combined flow may ultimately be discharged from the outlet 30 . In the exemplary engine of FIG. 1 , the blade stages of the turbine section 42 are co-spooled with the fan on the shaft 34 . The positioning of the turbine section 42 forward of the combustor section 40 , along with the generally forward flow through the turbine section 42 facilitates a short shaft 34 and a longitudinally compact engine. The configuration also hides the moving/hot surfaces of the turbine section 42 from line-of-sight exposure through the outlet. This may be advantageous for low observability properties including radar return and infrared signature. FIG. 1 shows further details of the exemplary combustor section 40 . FIG. 1 shows an inner member 80 within an outer member 82 . The airflow 516 is received through an associated conduit 84 to a volume or space 86 between the inner and outer members. There may be a circumferential array of the inner members 80 (one for each combustor 41 ). In some variations, the outer member 82 may be a single outer member containing all or more than one of the inner members (e.g., an annular outer member). In other variations, there may be a circumferential array of the outer members 82 , each containing an associated one of the inner members 80 . The exemplary inner member 80 has an aft end 90 and a fore end 92 . The exemplary inner member 80 has a first frustoconical wall portion 94 diverging forward from the aft end 90 . The wall portion 94 is foraminate allowing the inflow of air. In the exemplary combustor, a fuel injector 100 may be positioned at the aft end to introduce the fuel flow 518 . An igniter 102 (e.g., a sparkplug) may be positioned to ignite the fuel air mixture to cause combustion. The divergence of the wall portion 94 helps facilitate a deflagration-to-detonation transition. The exemplary inner member 80 has a second wall portion 110 forward of the portion 94 . A convergent wall portion 112 is downstream of the portion 110 . An outlet conduit 114 connects the inner member 80 to the associated turbine section 52 . Individual coupling of the combustors to at least the turbine section 52 prevents crosstalk between the discharge ends of the combustors. This is relevant where the combustors are operated out-of-phase so that the combustion gas discharged by one combustor is not ingested by another. Inlet decoupling is less critical. Thus, there may be a common outer member 82 defining a common inlet plenum. In yet other embodiments, each combustor may be coupled to receive air from the compressor section 50 of one unit 38 while discharging gases to the turbine section 52 of another unit. FIG. 3 shows an alternative configuration with a long shaft 34 ′ connecting a turbine section 42 ′ to the fan. The exemplary turbine section 42 ′ is aft of the combustor section and receives combustion gases from the compressor/turbine unit array through a manifold 160 ′ directing the combustion gases generally aftward and radially inboard of the combustors. The discharged combustion gases and bypass air mix relatively downstream. The effects of the pressure pulses from the individual combustors is minimized by operation out-of-phase with each other. Exemplary firing frequency may be in the vicinity of 50-300 Hz and may vary considerably depending on the scale/size of the engine and resulting impact on combustor section geometry and volume. Various phase combinations are possible, including firing in opposed pairs to limit wobble. Exemplary fan spool speeds are 2000-20000 revolutions per minute (RPM), more narrowly 6000-12000 RPM. Exemplary speeds for the units 38 are 5000-50000 RPM, more narrowly 20000-35000 RPM as an approximation for the 6000-12000 RPM fan spool speeds under steady-state conditions. Many variations are possible. For example, the combustors take a variety of forms, including shapes, positions, and orientations. FIG. 4 shows an exemplary configuration wherein eight combustors are grouped in two groups concentrated on respective left and right sides of the engine. This creates a wide but small height package which may be advantageous for integration into the airframe of an aircraft (e.g., a fighter aircraft, unmanned aerial vehicle, or missile). One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the details of any particular application will influence the configuration of the combustor. Various features of the combustor may be fully or partially integrated with features of the turbine or the compressor. If applied in a redesign of an existing turbine engine, details of the existing engine may implement details of the implementation. The combustor may alternatively be used in applications beyond turbine engines. Accordingly, other embodiments are within the scope of the following claims.	A turbine engine has a case with an axis. A fan is mounted for rotation about the axis. A turbine is mechanically coupled to the fan to drive rotation of the fan about the axis. A number of compressor/turbine units are downstream of the fan and upstream of the turbine along a core flowpath. A number of compressors are coupled to the compressor/turbine units to receive air and deliver combustion gas to drive the turbine.	5
BACKGROUND OF THE INVENTION [0001] The present embodiments relate to transport cooling for grocery totes. [0002] Carbon dioxide (CO 2 ) is used to provide refrigeration for home grocery delivery. CO 2 provides reliable and tremendous cooling per unit mass and leaves no moisture as it melts. CO 2 pellets are also readily available, although expensive to use for shipping purposes. Dry ice is usually packed with the food product all around the food product, even in many instances covering same, prior to shipment. The filling of the dry ice results in shipping the container as a “one size fits all” approach with the dry ice. It is also not uncommon for the dry ice to be delivered manually with no understanding as to the correct amount of refrigeration needed for the product being shipped. As a result, the “one size fits all” approach is an inefficient and certainly can be an unnecessarily expensive process when shipping the grocery product. SUMMARY OF THE INVENTION [0003] There is therefore provided a method for allocating a chilling substance to a transport tote for preserving a food product therein, which includes measuring thermal properties of the food product to be transported; calculating environmental conditions for which the transport tote is to be exposed during transport; allocating an amount of the chilling substance to a container for being deposited in the transport tote for the preserving of the food product; and depositing the container in the transport tote. [0004] There is also provided an apparatus for preserving a food product for transport to an end user, which includes a transport tote having an internal space therein sized and shaped to receive the food product; and a sealed container in which CO 2 snow is contained, the sealed container positioned in the transport tote. [0005] Other features of the present embodiments are set forth herein and provided in the present claims. BRIEF DESCRIPTION OF THE DRAWING [0006] For a more complete understanding of the present invention, reference may be had to the following description of exemplary embodiments considered in connection with the accompanying drawing FIGURE, of which: [0007] The FIGURE shows a side view of an automated CO 2 portioning system embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0008] The FIGURE shows products, such as grocery products, shipped in totes or containers, which hold at least one and for many uses a plurality of bags of groceries. The totes can be packaged for the groceries to be shipped in a frozen state, a chilled state, or ambient. [0009] Before explaining the inventive embodiments in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, if any, since the invention is capable of other embodiments and being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. [0010] In the following description, terms such as a horizontal, upright, vertical, above, below, beneath and the like, are to be used solely for the purpose of clarity illustrating the invention and should not be taken as words of limitation. The drawings are for the purpose of illustrating the invention and are not intended to be to scale. [0011] The present embodiments provide a supplier for a shipper of grocery products with a solution for accurately allocating the right amount of CO 2 with each grocery tote depending upon the product being shipped in the tote. The amount of CO 2 to be used for each tote is based upon the products thermal characteristics, delivery time for the tote, the refrigeration necessary for the products being delivered, and environmental conditions to which the tote is subjected during the delivery to the recipient. [0012] Referring to the FIGURE, there is disclosed how the process of the present embodiments works for the automated CO 2 portioning system for grocery totes in the present embodiments. In particular and referring to the FIGURE, a system for a method is shown generally at 10 and includes the following stages. [0013] (1) Empty grocery totes 12 , boxes or containers enter an automatic conveyor line 14 or conveyor belt. The conveyor line 14 includes an inlet 16 and an outlet 18 . The tote 12 has an internal space 20 which can be closed off with a top 22 by way of for example flaps of closure material. The internal space 20 is sized and shaped to receive at least one and for many applications a plurality of groceries 24 or grocery bags containing a food product or products, in addition to a snow box 26 . [0014] (2) The totes 12 are filled with the groceries 24 specific to a customer's order. Thermal characteristics of the groceries 24 are known and uploaded into a database (ie., storage temperature, mass, specific heat, latent heat, etc.). The thermal mass of the groceries 24 in each tote 12 can be calculated. The top 22 of the tote 12 remains in an open position for a purpose to be described hereinafter. [0015] (3) The snow box 26 (insulated box for holding CO 2 snow 28 or CO 2 pellets) is positioned in the internal space 20 near a top of the delivery tote 12 . During this step, the computer system (not shown) calculated the amount of CO 2 snow 28 required for transport based on the following variables, ie. thermal properties of food=thermal mass, desired holding temperature of product, external conditions for the day (outside temperature, humidity over the course of the day), delivery time to customer site, amount of time the tote 12 will remain at the customer site, conditions of a delivery platform transporting the tote 12 such as for example conditions inside a delivery truck (chilled, frozen, ambient). The delivery platform may be intermodal, ie transportable in an intermodal delivery platform where, for purposes herein, “intermodel delivery platform” refers to transport of freight in an intermodal container or vehicle (truck, ship, rail) without any handling of the freight itself when changing modes. With these variables, accurate heat transfer calculations can be made which will result in an estimate of the amount of CO 2 snow 28 required to be deposited in the snow box 26 for use with the groceries 24 in the tote 12 . [0016] (4) The calculated amount of CO 2 snow 28 is automatically dispensed or deposited in the snow box 26 as per stage (3) above. The snow box 26 is sealed to prevent direct contact with the CO 2 pellets in the snow box. [0017] (5) The tote 12 is closed by moving the top 22 , such as the flaps for example, into a position to seal off access to the internal space 20 of the tote. The tote 12 then exits the conveying line 14 for loading into trucks (not shown) and shipment to customer(s) at a remote location. [0018] An alternative embodiment calls for the snow box 26 to be filled separately with the CO 2 snow 28 , possibly at a remote location from the conveyor line 14 shown, after which the snow box is deposited on top of the grocery products 24 in the tote. The top 22 , or open-end of the tote, can have a movable cover or a pair of flaps which overlap to seal the opening of the internal space 20 of the tote after the grocery products 24 and snow box 26 are deposited therein. [0019] The snow box 26 rests on top of the grocery products 24 for chilling or maintaining same in a frozen state. The grocery products 24 do not have to be packaged, but can instead by unwrapped items such as for example apples, pears, IQR (individual quick frozen) shrimp, etc. [0020] It will be understood that the embodiments described herein are merely exemplary, and that a person skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. It should be understood that the embodiments described above are not only in the alternative, but can be combined.	A method for allocating a chilling substance to a transport tote for preserving a food product therein includes measuring thermal properties of the food product to be transported; calculating environmental conditions for which the transport tote is to be exposed during transport; allocating an amount of the chilling substance to a container for being deposited in the transport tote for the preserving of the food product; and depositing the container in the transport tote. A related apparatus is also provided.	5
FIELD OF THE INVENTION This invention relates generally to wireless communications networks and similar electronic systems and, in particular, to microwave filter components for wireless communications networks. BACKGROUND OF THE INVENTION Wideband, high-data-rate wireless communications networks based on cellular technologies are used worldwide for delivering an ever increasing amount of information to a mobile society. According to fundamental principles of cellular technology, a coverage area is divided into multiple cells that are mutually arranged to communicate with mobile stations or devices with minimal interference. Communications from a mobile station crossing the coverage area is handed-off between adjacent cells according to the location of the mobile station within the coverage area. Each of the cells is generally served by a base station having a transceiver that communicates with the mobile device. The frequency spectrums of the communications signals associated with the cells are divided into multiple different frequency bands. Therefore, filters, such as passive microwave filters, are used to perform band pass and band reject functions for separating the different frequency bands. Cell sizes are often reduced as information bandwidth handled by the cells increases. As a consequence, additional cells are required within a coverage area to provide wireless communication service to an increasing number of mobile stations. Increasing numbers of passive microwave filters are included in tower-mounted amplifiers and related equipment to address the bandwidth increases. Conventional microwave filters include a metallic shell or filter body having dividing walls that partition an open interior space into recesses and a cover that closes the recesses to define air-filled filter cavities or resonators. The metalworking process forming the filter body must accommodate precise dimensioning of the recesses to achieve satisfactory filter performance. Typically, the filter body is formed by casting and the cover is formed separately by either casting or stamping. After forming, the filter body may require additional machining for tuning the resonators as desired. The cover and filter body are assembled together to complete the microwave filter. A seam is defined about the contacting circumferences of the filter body and the cover. After assembly, the cover must have a good electrical contact with the filter body along the entire extent of the seam to ensure proper filter operation. If the microwave filter is exposed to an outdoor environment, the seam must be hermetically sealed against the infiltration of water and other elements so that the resonators remain moisture-free. The presence of moisture in the resonators reduces the long-term reliability of the microwave filter. Generally, such conventional microwave filters are relatively expensive to manufacture. In particular, the need to manufacture the precisely dimensioned resonators and a separate cover increases the cost as each component must be individually manufactured and assembled together. The physical size of conventional microwave filters may be reduced by loading inserts of a temperature stable ceramic material characterized by a high dielectric constant and a high quality factor into the recesses previously filled with air. However, despite the reduction in size, the manufacturing cost is not significantly reduced as the microwave filter still includes a filter body and cover, and the ceramic inserts must be loaded into the recesses within the filter body. Additionally, to address the cost issue, certain microwave filters incorporate commercially-available metallized ceramic resonators into a low-precision, low-cost sheet metal filter body. The presence of the ceramic reduces the size of the microwave filter. However, such composite structures lack the relatively-low insertion losses and relatively-high rejection numbers required for tower-mounted amplifiers currently used in wireless communication networks. Therefore, filter performance suffers. Therefore, it would be desirable to provide a microwave filter which addresses the problematic seams and cost issues associated with precision formed filters. It would also be desirable to address the performance disadvantages associated with low-cost conventional microwave filters. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a ceramic insert for a microwave filter in accordance with the principles of the invention; FIGS. 2A-2D are diagrammatic views showing a method for manufacturing the microwave filter of the invention; FIG. 3 is a perspective view of the completed microwave filter; and FIG. 4 is a cross-sectional view in accordance with an alternative embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION With reference to FIG. 1 , a ceramic element or insert 10 is fashioned from a machinable, castable or extrudable ceramic characterized by being easily shaped with standard manufacturing methods, unaffected structurally by high temperatures and high pressures encountered during a die casting process, and a low dissipation factor. An exemplary ceramic material suitable for forming the ceramic insert 10 is boron nitride, which is stable in inert and reducing atmospheres up to about 3000° C. and in oxidizing atmospheres to about 850° C., and is machinable using ordinary machine tools formed of hardened tool steel. Boron nitride has a high thermal conductivity of 20 W/(m−K) at room temperature and an excellent thermal shock resistance exceeding 1500° C. Boron nitride has a dissipation factor (measured according to ASTM D-150) of about 0.0011. The ceramic insert 10 includes a plurality of annular or tubular resonator regions 12 , 14 , 16 , 18 , 20 and 22 and a corresponding plurality of cavities 24 , 26 , 28 , 30 , 32 and 34 each surrounded by a corresponding one of the resonator regions 12 , 14 , 16 , 18 , 20 and 22 . The resonator regions 12 , 14 , 16 , 18 , 20 and 22 are electrically connected in series to form a main coupling path for microwave signals through the microwave filter 65 ( FIGS. 2D , 3 ). The electrical response of the microwave filter 65 , formed using the ceramic insert 10 as described below, may be altered by varying the proximity of adjacent resonator regions 12 , 14 , 16 , 18 , 20 and 22 . The number of resonator regions 12 , 14 , 16 , 18 , 20 and 22 is not limited, although microwave filter 65 will typically have four to eight distinct resonator regions. The cavities 24 , 26 , 28 , 30 , 32 and 34 are aligned parallel to one another and each of the illustrated cavities 24 , 26 , 28 , 30 , 32 and 34 has a generally circular cross-sectional profile. However, the invention is not so limited as the cross-sectional profile of the individual cavities 24 , 26 , 28 , 30 , 32 and 34 may be, among other examples, elliptical, rectangular or square. The resonator regions 12 , 14 , 16 , 18 , 20 and 22 may be dimensioned, shaped, and arranged, as understood by a person of ordinary skill in the art, to provide, for example, a comb-line filter, interdigital filter or a wave guide filter. The ceramic insert 10 may be a monolithic structure in which the resonator regions 12 , 14 , 16 , 18 , 20 and 22 are joined by individual bridging segments 23 of ceramic, as shown in FIG. 1 , or may constitute individual components arranged in a side-by-side, contacting relationship after the microwave filter 65 ( FIGS. 3A , 3 B) is formed. In that latter situation, the individual resonator regions 12 , 14 , 16 , 18 , 20 and 22 may include side flats that assist in maintaining the mutual arrangement among the resonator regions 12 , 14 , 16 , 18 , 20 and 22 during the die casting process that creates the microwave filter 65 . The space between the adjacent pairs of the resonator regions 12 , 14 , 16 , 18 , 20 and 22 normally should not be filled by metal during the die casting operation. The bridging segments 23 fill the inter-resonator spaces. An alternative approach for forming the ceramic insert 10 without the necessity of machining of a ceramic block is ceramic injection molding, which would provide, as an end product, a unitary, monolithic structure of a green ceramic in which the individual resonator regions 12 , 14 , 16 , 18 , 20 , and 22 are interconnected. A slurry of a ceramic powder and a polymeric binder is injected in an injection molding machine into a mold having a shape complementary to the shape of the ceramic insert 10 . The “green” ceramic insert 10 is heated to remove the polymeric binder and then sintered to strengthen the bonds among grains of the ceramic powder. With reference to FIG. 2A , a die casting machine, generally indicated by reference numeral 40 , includes a stationary platen 42 to which a cover die 44 is attached and a movable platen 46 to which an ejector die 48 is attached. A shaped die cavity 50 is defined between the contacting cover die 44 and ejector die 48 . Movement of the movable platen 46 relative to the stationary platen 42 affords access to the die cavity 50 . A plurality of ejectors 52 penetrate through the ejector die 48 and are extendable into the die cavity 50 for ejecting the partially-completed microwave filter 65 from the die cavity 50 when the cover die 44 is spaced apart from the ejector die 48 . A metal reservoir 54 is defined in a shot sleeve 56 having one end communicating with the die cavity 50 and an opposite end having an inlet 58 adapted to receive molten metal 60 provided from a metering device 62 , such as a ladle. A piston 64 of a hydraulic cylinder extends into the shot sleeve 56 . The piston 64 is extendable relative to the shot sleeve 56 for injecting molten metal 60 from the shot sleeve 56 into the die cavity 50 . With reference to FIGS. 2A-2D , the manufacture of the microwave filter 65 using the ceramic insert 10 will be described in accordance with the principles of the invention. As described above with reference to FIG. 1 , the ceramic insert 10 is formed by either casting, extrusion or injection molding. The movable platen 46 is moved relative to the stationary platen 42 to afford access to the die cavity 50 . As shown in FIG. 2A , the ceramic insert 10 is inserted into the die cavity 50 and the movable platen 46 is moved to close the die cavity 50 . A metered volume of molten metal 60 , typically aluminum or an aluminum alloy, is introduced through the inlet 58 into the reservoir 54 of the shot sleeve 56 . As shown in FIG. 2B , the piston 64 is moved within the shot sleeve 56 for introducing the molten metal 60 into the die cavity 50 under high pressure. The molten metal 60 fills the open space within the die cavity 50 not otherwise occupied by the ceramic insert 10 , including the resonator regions 12 , 14 , 16 , 18 , 20 and 22 . After the metal 60 has solidified, the movable platen 46 is moved to again afford access to the die cavity 50 and the ejectors 52 are extended to dislodge and remove a partially-completed microwave filter 65 . With reference to FIG. 2C , after solidification, the microwave filter 65 has an elongated outer casing 66 of metal 60 that encapsulates the ceramic insert 10 . Metal 60 filling the cavities 24 , 26 , 28 , 30 , 32 and 34 of the ceramic insert 10 define individual resonator rods. With reference to FIGS. 2D and 3 , the outer casing 66 may be machined, such as by laser machining or electromachining, to add an input port 68 for introducing an electrical signal into the microwave filter 65 and an output port 70 for extracting a filtered signal. The casing 66 may be further machined to provide threaded openings for tuning adjustment elements 72 that are operative for adjusting the resonant frequency of the cavities 24 , 26 , 28 , 30 , 32 and 34 by adjusting the position of each tuning element relative to the metal 60 to change the volume of a corresponding one of a plurality of air gaps 73 . Although the tuning adjustment elements 72 are depicted as threaded screws, other types of tuning adjustment elements may be added without deparating from the spirit and scope of the invention. The microwave filter 65 is tuned and tested before being deployed for use. The microwave filter 65 is a monolithic unit, generally having the shape of a right parallelepiped, that lacks any seams that would otherwise present entry paths for moisture from the surrounding environment. In addition, the absence of a discrete cover and a discrete filter body, as is conventional, eliminates the need to establish a good electrical contact about the entire mutual line-of-contact. A microwave filter in accordance with the principles of the invention is low cost, high performance, seamless and more compact than conventional microwave filters. The microwave filter 65 may be configured as a comb-line filter, interdigital filter or a wave guide filter. The invention contemplates that other passive microwave components may be formed by the method of the invention. With reference to FIG. 4 in which like reference numerals refer to like features in FIG. 2D , a microwave filter 74 may include a plurality of resonator rods 76 , 78 , and 80 , of which only three resonator rods are shown, each filling one of the corresponding cavities 24 , 26 , and 28 of the dielectric insert 10 . In one embodiment, the resonator rods 76 , 78 , and 80 are shorter than the length of the resonator to create an air gap 79 in the cavities 24 , 26 , 28 , 34 . During the molding, appropriate steps may be taken to keep molten metal out of the cavities 24 , 26 , 28 , 34 . Resonator rods 76 , 78 , and 80 are coaxially positioned within the corresponding one of the cavities 24 , 26 , and 28 and 34 before the ceramic insert 10 is positioned in the die cavity 50 ( FIG. 2A ) and molten metal 60 is injected into the die cavity 50 . The cross-sectional profile of each of the resonator rods 76 , 78 , and 80 closely matches the cross-sectional profile of the corresponding one of the cavities 24 , 26 , and 28 . The resonator rods 76 , 78 , and 80 are formed from a metal that differs in composition from the metal 60 injected during the die casting operation ( FIGS. 3A , 3 B). After the microwave filter 74 is die cast and the metal 60 solidifies, each resonator rod 76 , 78 , and 80 has a strong metallurgical bond with the inwardly-facing cylindrical sidewall of the corresponding one of the cavities 24 , 26 , and 28 in the ceramic insert 10 . The tuning adjustment elements 72 and the input and output ports 68 , 70 are added by machining operations, as described in relation to FIGS. 2C and 2D . Movement of each of the tuning adjustment elements 72 changes the volume of a corresponding one of a plurality of air gaps 79 . While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in considerable detail in order to describe a preferred mode of practicing the invention, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the spirit and scope of the invention will readily appear to those skilled in the art. The invention itself should only be defined by the appended claims, wherein	A simplified method for forming passive microwave components, such as a filter, and passive microwave components formed by the method. The method includes forming a ceramic insert having a plurality of resonator regions and then die casting an outer casing of a conductive material about the ceramic insert. Each resonator region has a cavity that may be filled with the conductive material used to die cast the outer casing or, alternatively, may be filled with a resonator rod made of different materials than the encapsulating metal.	8
FIELD OF THE INVENTION [0001] The invention relates to additives and plating bath compositions for electro-deposition of copper or copper alloys. The plating bath compositions are suitable in the manufacture of printed circuit boards, IC substrates and the like as well as for metallization of semiconducting and glass substrates. BACKGROUND OF THE INVENTION [0002] Aqueous acidic plating baths for electrolytic deposition of copper are used for manufacturing printed circuit boards and IC substrates where fine structures like trenches, through holes (TH), blind micro vias (BMV) and pillar bumps need to be filled or build up with copper. Another application of such electrolytic deposition of copper is filling of recessed structures such as through silicon vias (TSV) and dual damascene plating or forming redistribution layers (RDL) and pillar bumps in and on semiconducting substrates. Still another application which is becoming more demanding is filling through glass vias, i.e. holes and related recessed structures in glass substrates with copper or copper alloys by electroplating. [0003] The patent application EP 1 069 211 A2 discloses aqueous acidic copper plating baths comprising a source of copper ions, an acid, a carrier additive, a brightener additive and a leveler additive which can be poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea (CAS-No. 68555-36-2) which contains an organo-bound halide atom (e.g., covalent C—Cl bonds) in at least one terminus (see comparative preparation example 1). [0004] Such leveler additives in acidic copper plating baths are not suitable to fulfill the current and future requirements in manufacture of advanced printed circuit boards, IC substrates and metallization of semiconducting and glass substrates. Depending on the circuitry layout, BMVs′ in printed circuit boards and IC substrates need to be filled with copper completely and not only conformally. Typical requirements for BMV filling are for example: obtaining a completely filled BMV while depositing no more than 10 to 15 μm of copper onto the neighbouring planar substrate areas and at the same time creating a dimple on the outer surface of the filled BMV of no more than 0 to 10 μm. [0005] In metallization of semiconducting wafers, TSV filling must lead to a complete and void-free filling with copper while creating no more than ⅕ of via diameter of overplated copper onto the neighbouring planar areas. Similar requirements are demanded for filling through glass vias with copper. Objective of the Invention [0006] Thus, it is an objective of the present invention to provide an aqueous acidic copper plating bath for electrolytic deposition of copper or copper alloys which fulfills the requirements for the above mentioned applications in the field of printed circuit board and IC substrate manufacturing as well as metallisation of semiconducting substrates like TSV filling, dual damascene plating, deposition of redistribution layers or pillar bumping and filling of through glass vias. SUMMARY OF THE INVENTION [0007] This objective is solved with an aqueous acidic plating bath composition comprising a source of copper ions, an acid and at least one ureylene polymer having terminal amino groups on both ends (termini) of the polymer chain wherein said aqueous acidic copper electroplating bath is free of intentionally added zinc ions. [0008] Recessed structures such as trenches, blind micro vias (BMVs′), through silicon vias (TSVs′) and through glass vias can be filled with copper deposited from the aqueous acidic copper plating bath according to the present invention. The copper filled recessed structures are void free and have an acceptable dimple, i.e., a planar or almost planar surface. Furthermore, the build-up of pillar bump structures is feasible. BRIEF DESCRIPTION OF THE FIGURES [0009] FIG. 1 shows the 1 H-NMR spectrum of the ureylene polymer obtained in preparation example 1a. [0010] FIG. 2 shows the 1 H-NMR spectrum of the ureylene polymer poly[bis(2-chloroethyl)-ether-alt-1,3-bis[3-(dimethylamino)propyl]urea (comparative preparation example 1). [0011] FIG. 3 shows a copper filled blind micro via obtained in application example 1. [0012] FIG. 4 shows copper filled through-silicon vias obtained in comparative application example 1. [0013] FIG. 5 shows copper filled through-silicon vias obtained in application example 23. DETAILED DESCRIPTION OF THE INVENTION [0014] The aqueous acidic copper plating bath according to the present invention comprises at least one ureylene polymer of the following Formulae (I), (III) and (III) [0000] [0000] wherein A independently represents a unit derived from a diamino compound of one of the following Formulae (IV) and (V) [0000] [0000] R1, R2, R5, and R6 are independently selected from the group consisting of hydrogen, a substituted or unsubstituted hydrocarbon residue with 1 to 10 carbon atoms, preferably methyl, ethyl, hydroxyethyl or —CH 2 CH 2 (OCH 2 CH 2 ) a —OH, wherein a is an integer from 0 to 4, and R3 and R4 are independently selected from the group consisting of (CH 2 ) p , wherein p is an integer from 2 to 12, preferably for an ethylene or propylene group, or for a —[CH 2 CH 2 O] m —CH 2 CH 2 — group, wherein m is an integer from 1 to 40, preferably for a —(CH 2 ) 2 —O—(CH 2 ) 2 — or —(CH 2 ) 2 —O—(CH 2 ) 2 —O—(CH 2 ) 2 — group, Z may be the same or different and represents O or S, preferably, Z is the same, most preferably, Z is O, x and y may be the same or different and are preferably an integer selected from 1, 2 and 3, more preferably x and y are both 2; wherein A′ represents a unit derived from an amine of the Formula (VI) [0000] [0000] wherein R7 and R8 are independently selected from the group consisting of hydrogen, a substituted or unsubstituted hydrocarbon residue preferably with 1 to 16 carbon atoms, more preferably with 1 to 10 carbon atoms, linear or branched, hydroxyethyl or —CH 2 CH 2 (OCH 2 CH 2 ) a —OH, wherein a is an integer from 1 to 4, substituted or unsubstituted alkaryl, alkhetaryl, allyl or propargyl, and wherein L stands for a divalent residue, which is selected from the group consisting of —(CH 2 ) p —, wherein p is an integer from 1 to 12, preferably from 1 to 6, and most preferably from 2 to 4, —CH 2 —CH(OH)—CH 2 —, —[CH 2 O] q —CH 2 CH 2 —, —[CH 2 CH 2 O] q —CH 2 CH 2 —, —CH 2 —CH(SH)—CH 2 —, —[CH 2 S] q —CH 2 CH 2 —, —[CH 2 CH 2 S] q —CH 2 CH 2 —, —CH 2 —CH(OH)—CH 2 —R9-CH 2 —CH(OH)—CH 2 — and —CH 2 CH(OH)CH 2 — wherein q is an integer from 1 to 40, preferably —CH 2 —O—(CH 2 ) 2 —, —(CH 2 ) 2 —O—(CH 2 ) 2 — or —(CH 2 ) 2 —O—(CH 2 ) 2 —O—(CH 2 ) 2 — and wherein R9 is selected from the group consisting of a substituted or unsubstituted hydrocarbon residue preferably with 0 to 10 carbon atoms, more preferably from to 2 carbon atoms, —O—CH 2 CH(OH)—CH 2 O— and —O—[CH 2 CH 2 O] q —CH 2 O—, wherein q is an integer preferably from 1 to 40, more preferably from 1 to 30 and most preferably from 1 to 12; wherein the single units A may be the same or different, wherein the single units A′ may be the same or different, wherein the single units L may be the same or different, wherein n represents an integer and preferably ranges from 1 to 40, more preferably from 3 to 30 and most preferably from 5 to 20, and wherein the polymers according to Formula (I) have units A at both ends of the polymer chain, the polymers according to Formula (II) have units A′ at both ends of the polymer chain and the polymers according to Formula (III) have a unit A at one end and a unit A′ at the other end of the polymer chain. [0015] R1, R2, R5 and R6 may represent, as mentioned before, a substituted or unsubstituted hydrocarbon residue having 1 to 10 carbon atoms, preferably methyl, ethyl, hydroxyethyl or —CH 2 CH 2 (OCH 2 CH 2 ) y —OH, wherein y is an integer from 1 to 4. The aforementioned hydrocarbon residues can, in particular, be substituted with C 1 -C 6 alkyl (preferably —CH 3 , —CH 2 CH 3 ), aryl (preferably phenyl) or aralkyl (preferably benzyl). [0016] The term “polymer” has to be understood in a broad sense in connection with the present invention. It comprises any compound which has been formed by reaction of at least two monomer unit A and one divalent residue L (polymers according to Formula (I)), any compound which has been formed by reaction of at least two monomer unit A, one monomer unit A′ and two divalent residues residues L (polymers according to Formula (II)) and any compound which has been formed by reaction of at least one monomer unit A, two monomer unit A′ and two divalent residues L (polymers according to Formula (III) with n=1). The term “polymer” does comprise, in particular, compounds which are typically designated as oligomers. The term “polymer” is, in connection with the present invention also applied to compounds, which are formed by a poly “condensation” reaction. [0017] The ureylene polymer of Formulae (I), (II) and (III) can be obtained by reacting one or more diamino compounds of Formulae (IV) and/or (V) with one or more compounds of the following Formulae (VII), [0000] P-L-Q (VII) [0000] wherein L has the same meaning as in Formulae (I), (II) and (III) and wherein P and Q may each be the same or different and represent halogens such as Cl, Br and I or pseudohalogens such as mesylate, triflate, nonaflate, methanesulfonate, or tosylate. [0018] The ureylene polymers according to Formulae (I), (II) and (III) can also be obtained by reacting one or more diamine compounds according to Formulae (IV) and/or (V) with one or more compounds of the Formula (VIII) which form the divalent residue L. Accordingly, the divalent residue L in a polymer according to Formulae (I), (II) and (III) is a —CH 2 —CH(OH)—CH 2 —R9-CH 2 —CH(OH)—CH 2 — residue. [0000] [0019] The compounds of the Formula (VIII) are diglycidyl or compounds or di-epoxides wherein R9 is selected from the group consisting of a substituted or unsubstituted hydrocarbon residue preferably with 0 to 10 carbon atoms, more preferably from 0 to 2 carbon atoms, —O—CH 2 CH(OH)—CH 2 O— and —O—[CH 2 CH 2 O] q —CH 2 O—, wherein q is an integer preferably from 1 to 40, more preferably from 1 to 30 and most preferably from 1 to 12. [0020] The ureylene polymers according to Formulae (I), (II) and (III) can also be obtained by reacting one or more diamine compounds according to Formulae (IV) and/or (V) with one or more compounds of the Formula (IX) which form the divalent residue L. Accordingly, the divalent residue L in a polymer according to Formulae (I), (II) and (III) is a —CH 2 CH(OH)CH 2 — residue. [0000] [0021] The compounds of the Formula (IX) are epi(pseudo)halohydrines wherein P represents halogens such as Cl, Br and I or pseudohalogens such as OMs (mesylate), OTf (triflate), ONE (nonaflate), methanesulfonate, or OTs (tosylate). [0022] In the case of the compounds of Formulae (VIII) and (IX) the linkages L between the units A occur via quaternary ammonium groups under formation of betainic structure moieties which are formed by opening the epoxide-structure by the tertiary amino groups from compounds according to Formulae (IV) and (V). The resulting polymers can be acidified by an appropriate mineral acid, such as hydrohalide acid, alkylsulfonic acid, arylsulfonic acid or sulfuric acid. [0023] The molar ratio (n A :n B ) of the total amount of substance used of the compound(s) of Formulae (IV) and/or (V) (n A ) to the total amount of substance of the compound(s) of Formulae (VII), (VIII) and (IX) (n B ) is preferably at least 1.1:1, more preferably 1.3:1, and most preferably at least 1.5:1. [0024] Thereby, the ureylene polymers according to Formula (I) are obtained with units A having amino groups at both ends of the polymer chain and which do not comprise organically bound halogen such as a C—Cl moiety. [0025] The ureylene polymers of Formula (II) can be obtained by reacting one or more diamino compounds of Formulae (IV) and/or (V) with one or more compounds of Formulae (VII), (VIII) and (IX) wherein the molar ratio (n A :n B ) of the total amount of substance used of the compound(s) of Formulae (IV) and/or (V) (n A ) to the total amount of substance of the compound(s) of Formulae (VII), (VIII) and (IX) (n B ) is 1:1 The intermediate polymers obtained have the Formula (X) [0000] [0026] The ureylene polymers according to Formula (III) are obtained by reacting one or more diamino compounds of Formulae (IV) and/or (V) with one or more compounds of Formulae (VII), (VIII) and (IX) wherein the molar ratio (n A :n B ) of the total amount of substance used of the compound(s) of Formulae (IV) and/or (V) (n A ) to the total amount of substance of the compound(s) of Formulae (VII), (VIII) and (IX) (n B ) is at least 1:1.1, more preferably at least 1:1.3, and most preferably at least 1:1.5. The intermediate polymers obtained have the Formula (XI) [0000] [0027] Both intermediate ureylene polymers according to Formulae (X) and (XI) are further reacted with a compound according to Formula (VI) in order to obtain an ureylene polymer according to Formula (II) or (III). The ureylene polymers according to Formulae (II) or (III) then comprise units A′ having amino groups at both ends (polymer according to Formula (III)) or a unit A′ at one end and a unit A at the other end of the polymer chain (polymer according to Formula (II)) and no organically bound halogens such as a C—Cl moiety. [0028] The linkages between units A (and A′) and residues L occur via quaternary ammonium groups, which are formed linking the divalent residue L with the tertiary amino groups of the compounds of the Formulae (IV) and/or (V). [0029] These terminal tertiary amino groups may be quaternized in accordance with the desired properties by using an organic (pseudo)monohalide, such as benzyl chloride, allyl chloride, alkyl chloride, such as 1-chloro-hexane or their corresponding bromides and mesylates, or by using an appropriate mineral acid, such as hydrochloric acid, hydrobromic acid, hydroiodic acid or sulfuric acid. [0030] The ureylene polymers of the Formulae (I), (II) and (III) preferably have a weight average molecular mass M W of 1000 to 20000 Da, more preferably of 2000 to 15000 Da. [0031] The reaction of diamino compounds of the Formulae (IV) and (V) with the compounds of the Formulae (VII), (VIII) and (IX) may preferably be carried out in aqueous or aqueous-alcoholic solutions or solvent-free substances at temperatures of preferably 20 to 100° C. [0032] The ureylene polymers of the Formulae (I), (II) and (III) do not contain any organically bound halogen, such as a covalent C—Cl moiety. [0033] In another embodiment of the present invention, halide ions serving as the counter ions of the positively charged ureylene polymers according to Formulae (I), (II) and (III) are replaced after preparation of the polymer by anions such as methane sulfonate, hydroxide, sulfate, hydrogensulfate, carbonate, hydrogencarbonate, alkylsulfonate such as methane sulfonate, alkarylsulfonate, arylsulfonate, al kylcarboxylate, al karylcarboxylate, arylcarboxylate, phosphate, hydrogenphosphate, dihydrogenphosphate, and phosphonate. The halide ions can be for example replaced by ion exchange over a suitable ion exchange resin. The most suitable ion exchange resins are basic ion exchange resins such as Amberlyst® A21. Halide ions can then be replaced by adding an inorganic acid and/or an organic acid containing the desired anions to the ion exchange resin. The enrichment of halide ions in the aqueous acidic copper plating bath during use can be avoided if the polymers according to Formulae (I), (II) and (III) contain anions other than halide ions. [0034] The concentration of the at least one ureylene polymer according to Formulae (I), (II) and (III) in the aqueous acidic copper plating bath preferably ranges from 0.001 mg/l to 200 mg/l, more preferably from 0.005 mg/l to 100 mg/l and most preferably from 0.01 mg/l to 50 mg/l. [0035] The aqueous acidic copper plating bath composition preferably has a pH value of ≦2, more preferably of ≦1. [0036] The aqueous acidic copper plating bath further contains at least one source of copper ions which is preferably selected from the group comprising copper sulfate and copper alkyl sulfonates such as copper methane sulfonate. The copper ion concentration in the aqueous acidic copper plating bath preferably ranges from 4 g/l to 90 g/l. [0037] The aqueous acidic copper plating bath further contains at least one source of acid which is preferably selected from the group comprising sulfuric acid, fluoroboric acid, phosphoric acid and methane sulfonic acid and is preferably added in a concentration of 10 g/l to 400 g/l, more preferably from 20 g/l to 300 g/l. [0038] The aqueous acidic copper plating bath preferably further contains at least one accelerator-brightener additive which is selected from the group consisting of organic thiol-, sulfide-, disulfide- and polysulfide-compounds. Preferred accelerator-brightener additives are selected from the group comprising 3-(benzthiazolyl-2-thio)-propylsulfonic-acid, 3-mercaptopropan-1-sulfonic-acid, ethylendithiodipropylsulfonic-acid, bis-(p-sulfophenyl)-disulfide, bis-(ω-sulfobutyl)-disulfide, bis-(ω-sulfohydroxypropyl)-disulfide, bis-(ω-sulfopropyl)-disulfide, bis-(ω-sulfopropyl)-sulfide, methyl-(ω-sulfopropyl)-disulfide, methyl-(ω-sulfopropyl)-trisulfide, O-ethyl-dithiocarbonic-acid-S-(ω-sulfopropyl)-ester, thioglycol-acid, thiophosphoric-acid-O-ethyl-bis-(ω-sulfopropyl)-ester, thiophosphoric-acid-tris-(ω-sulfopropyl)-ester and their corresponding salts. The concentration of all accelerator-brightener additives optionally present in the aqueous acidic copper bath compositions preferably ranges from 0.01 mg/l to 100 mg/l, more preferably from 0.05 mg/l to 10 mg/l. [0039] The aqueous acidic copper plating bath optionally further contains at least one carrier-suppressor additive which is preferably selected from the group comprising polyvinylalcohol, carboxymethylcellulose, polyethyleneglycol, polypropyleneglycol, stearic acid polyglycolester, alkoxylated naphthols, oleic acid polyglycolester, stearylalcoholpolyglycolether, nonylphenolpolyglycolether, octanolpolyalkylenglycolether, octanediol-bis-(polyalkylenglycolether), poly(ethylenglycol-ran-propyleneglycol), poly(ethylenglycol)-block-poly(propylenglycol)-block-poly(ethylenglycol), and poly(propylenglycol)-block-poly(ethylenglycol)-block-poly(propylenglycol). More preferably, the optional carrier-suppressor additive is selected from the group comprising polyethylenglycol, polypropylenglycol, poly(ethylenglycol-ran-propylenglycol), poly(ethylenglycol)-block-poly(propylenglycol)-block-poly(ethylenglycol), and poly(propylenglycol)-block-poly(ethylenglycol)-block-poly(propylenglycol). The concentration of said optional carrier-suppressor additive preferably ranges from 0.005 g/l to 20 g/l, more preferably from 0.01 g/l to 5 g/l. [0040] Optionally, the aqueous acidic copper plating bath contains in addition to the ureylene polymer according to Formulae (I), (II) or (III) at least one further leveler additive selected from the group comprising nitrogen containing organic compounds such as polyethyleneimine, alkoxylated polyethyleneimine, alkoxylated lactams and polymers thereof, diethylenetriamine and hexamethylenetetramine, organic dyes such as Janus Green B, Bismarck Brown Y and Acid Violet 7, sulphur containing amino acids such as cysteine, phenazinium salts and derivatives thereof. The preferred further leveler additive is selected from nitrogen containing organic compounds. Said optional leveler additive is added to the aqueous acidic copper plating bath in amounts of 0.1 mg/l to 100 mg/l. [0041] The aqueous acidic copper plating bath optionally further contains at least one source of halogenide ions, preferably chloride ions in a quantity of 20 mg/l to 200 mg/l, more preferably from 30 mg/l to 60 mg/l. Suitable sources for halogenide ions are for example alkali halogenides such as sodium chloride. [0042] The optional halogenide ions may be provided solely or partly by the ureylene polymer according to Formulae (I), (II) or (III) when the counter ions are halogenide ions. [0043] The aqueous acidic copper plating bath is preferably operated in the method according to the present invention in a temperature range of 15° C. to 50° C., more preferably in a temperature range of 25° C. to 40° C. by applying an electrical current to the substrate and at least one anode. Preferably, a cathodic current density range of 0.0005 A/dm 2 to 12 A/dm 2 , more preferably 0.001 A/dm 2 to 7 A/dm 2 is applied. [0044] The plating bath according to the present invention can be used for DC plating and reverse pulse plating. Both inert and soluble anodes can be utilised when depositing copper from the plating bath according to the present invention. [0045] In one embodiment of the present invention, a redox couple, such as Fe 2+/3+ ions is added to the plating bath. Such a redox couple is particularly useful, if reverse pulse plating is used combination with inert anodes for copper deposition. Suitable processes for copper plating using a redox couple in combination with reverse pulse plating and inert anodes are for example disclosed in U.S. Pat. No. 5,976,341 and U.S. Pat. No. 6,099,711. [0046] The aqueous acidic copper plating bath can be either used in conventional vertical or horizontal plating equipment. [0047] The aqueous acidic copper plating bath according to the present invention is essentially free of zinc ions. “Essentially free” is defined herein as “not intentionally added”. Hence, the aqueous acidic copper plating bath according to the present invention does not contain intentionally added zinc ions. [0048] The metal layer obtained by electroplating from said aqueous acidic copper plating bath is a copper or copper alloy layer. Accordingly, zinc and zinc alloy layers are not obtainable from said aqueous acidic copper plating bath because the bath does not contain intentionally added zinc ions. [0049] The invention will now be illustrated by reference to the following non-limiting examples. Examples [0050] 1 H-NMR spectra of the ureylene polymer obtained in preparation example 1a and comparative preparation example 1 were recorded at 500 MHz with a spectrum offset of 4300 Hz, a sweep width of 9542 Hz at 25° C. (Varian, NMR System 500). The solvent used was D 2 O. [0051] The weight average molecular mass M W of the ureylene polymers was determined by gel permeation chromatography (GPC) using a GPC apparatus from WGE-Dr. Bures equipped with a molecular weight analyzer BI-MwA from Brookhaven, a TSK Oligo+3000 column, and Pullulan and PEG standards with M W =400 to 22000 g/mol. The solvent used was Millipore water with 0.5 acetic acid and 0.1 M Na 2 SO 4 . Preparation of Ureylene Polymers According to Formula (I) Preparation Example 1a [0052] A polymer according to Formula (I) with a monomer A of Formula (IV) with R 1 and R2=methyl, R3 and R4=propyl and a monomer L with L=(CH 2 ) 2 O(CH 2 ) 2 was prepared according to preparation example 12 in WO 2011/029781 A1. [0053] The weight average molecular mass M W of the ureylene polymer obtained was 5380 Da. [0054] The 1 H-NMR spectrum of said polymer is shown in FIG. 1 . The 1 H-NMR spectrum shows a signal at 2.27 ppm which is characteristic of terminal N,N-dimethylamino groups. Further signals are observed at 1.67 ppm and 2.44 ppm which are characteristic for methyl residues bond to the terminal nitrogen atoms of the ureylene polymer. Preparation Example 1b [0055] The terminal amino residues of the ureylene polymer according to Formula (I) obtained by a similar procedure as preparation example 1 were quaternised with 1-chloro-hexane (80° C. for 29 h while stirring and then held at 90° C. for 60 h). The resulting ureylene polymer had a weight average molecular mass M W of 7303 Da. Preparation Example 2 [0056] A polymer with a monomer A of Formula (IV) with R1 and R2=methyl, R3 and R4=propyl and a monomer L with L=(CH 2 ) 2 O(CH 2 ) 2 O(CH 2 ) 2 was prepared according to preparation example 13 in WO 2011/029781 A1. [0057] The ureylene polymer obtained had a weight average molecular mass M W of 6306 Da. Preparation Example 3 [0058] 50 g (217.1 mmol) 1,3-bis(3-(dimethylamino)propyl-urea and 26.88 g (186.1 mmol) 1-chloro-2-(2-chloroethoxy)-ethane were together dissolved in 76.34 g water. The solution was then held at 90° C. for 12 h. 153.22 g of an aqueous polymer solution containing 50 wt.-% of the ureylene polymer (M W =11280 Da) were obtained. Preparation Example 4 [0059] 26.6 g (115 mmol) 1,3-bis-(3-(dimethylamino)-propyl)-urea were dissolved in 52.5 g water. 22.87 g (99 mmol) 1-chloro-2-(2-(2-chloroethoxy)-ethoxy)-ethane were added to this solution within 2 min at 80° C. while stirring. The resulting solution was further stirred at 80° C. for 24 h. 101.97 g of an aqueous polymer solution containing 48.51 wt.-% of the ureylene polymer (A=monomer according to Formula (IV) with R 1 and R 2 =methyl, R 3 and R 4 =propyl; L=(CH 2 ) 2 O (CH 2 ) 2 O (CH 2 ) 2 ; M W =13430 Da) were obtained. Preparation Example 5 [0060] 23.6 g (74.9 mmol) N,N′-bis(morpholinopropyl)-urea (monomer A according to Formula (V)) were dissolved in 58.3 g water and heated to 80° C. 15.3 g (64.2 mmol) 1-chloro-2-(2-(2-chloroethoxy)-ethoxy)-ethane were added to this solution within 1 min while stirring. The solution was then held at 80° C. for 10 h while stirring and then 24 h at 95° C. and finally refluxed for 48 h. 97.125 g of an aqueous polymer solution containing 40 wt.-% of the ureylene polymer (A=monomer according to Formula (V) with R 3 and R 4 =propyl and Z═O; L=(CH 2 ) 2 O (CH 2 ) 2 O (CH 2 ) 2 ; M W =2689 Da). Preparation Example 6 [0061] A polymer according to Formula (I) with a monomer A of Formula (IV) with R 1 and R 2 =methyl, R 3 and R 4 =propyl and a monomer L with L=(CH 2 ) 3 was prepared according to preparation example 10 in WO 2011/029781 A1. The weight average molecular mass M W of the ureylene polymer was 5380 Da. Preparation Example 7 [0062] The ureylene polymer obtained in preparation example 1a was ion exchanged with a basic ion exchanger III/OH − form (Amberlyst A21) and then mixed with methane sulfonic acid. [0063] The ureylene polymer obtained comprised then methane sulfonate anions instead of chloride ions. Preparation Example 8 [0064] 25 g 1,3-bis-(3-(dimethylamino)-propyl)-urea were dissolved in 50 g water. 21.36 g oxybis-(ethane-2,1-diyl)-dimethanesulfonate were added to this solution. The resulting solution was further stirred at 80° C. for 5.5 h. 92.72 g of an aqueous polymer solution containing 50 wt.-% of the ureylene polymer (A=monomer according to Formula (IV) with R 1 and R 2 =methyl, R 3 and R 4 =propyl; L=(CH 2 ) 2 O (CH 2 ) 2 O (CH 2 ) 2 ; M W =9461 Da) were obtained. Preparation Example 9 [0065] 25 g oxybis-(ethane-2,1-diyl)dimethansulfonate were dissolved in 39.10 g water. 14.10 g 1,3-bis[3-(dimethylamino)propyl]urea were added to this solution. The resulting solution was further stirred at 80° C. for 17 hours. Afterwards, 2.99 g butylamine were added and the resulting reaction mixture was stirred for additional 20 hours at 80° C. 81.2 g of an aqueous polymer solution containing 50 wt-% of the ureylene polymer according to Formula (II) were obtained (A=monomer according to Formula (IV) with R1 and R2=methyl; R3 and R4=propyl; L=(CH 2 ) 2 O (CH 2 ) 2 O (CH 2 ) 2 and A′ monomer according to Formula (VI) with R7=butyl and R8=hydrogen; M W =4600 Da. Comparative Preparation Example 1 [0066] Poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea (CAS-No. 68555-36-2), a leveler additive disclosed in EP 1 069 211 A2 was purchased from Sigma-Aldrich. [0067] The 1 H-NMR spectrum of said ureylene polymer (shown in FIG. 2 ) contains no signal at 2.27 ppm and thus contains no such terminal N,N-dimethylamino groups ( FIG. 1 ). Hence, poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)-propyl]urea contains no (detectable amount of) terminal amino groups and does not have amino groups at both ends of the polymer chain. Moreover, the signals at 1.67 ppm and 2.44 ppm observed in the 1H-NMR spectrum of the ureylene polymer according to Formula (I) obtained in preparation sample 1a ( FIG. 1 ) and the signal at 2.87 ppm observed in the 1H-NMR spectrum of poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea ( FIG. 2 ) show that both ureylene polymers are structurally different. [0000] Copper Deposition into BMVs′: [0068] The electrolyte baths containing the ureylene polymers prepared according to preparation examples 1a to 6 were used as additives for deposition of copper into recessed structures and then subjected to the following test method. [0069] A sufficient BMV filling with copper means that the copper deposit has no or almost no so-called dimple (depression of the copper surface at the point of the BMV). Hence, the copper surface of a sufficiently filled BMV is as even as possible. [0070] An insufficient BMV filling is characterised by a concave structure of the copper deposit, i.e. by a dimple. Voids in a copper filled via are also not desired. [0071] The cross sections of recessed structures filled with copper were investigated with an optical microscope after depositing a protection layer of nickel onto the copper deposit and applying conventional grinding and polishing methods. A copper filled BMV obtained in application example 1 is shown in FIG. 3 . [0072] The values for “dimple” were recorded with a chromatic sensor (Nanofocus μ-scan with sensor CRT5). Methods for Application Examples 1 to 16 [0073] Equipment: Gornall cell with 1.8 l volume, bath agitation with a pump, no air injection, soluble copper anodes. [0074] A copper plating bath stock solution comprising 45 g/l Cu 2+ ions (added as copper sulfate), 50 g/l sulfuric acid, 45 mg/l Cl − ions, 300 mg/l polyethyleneglycol as a carrier-suppressor additive and 1.0 ml/l of a solution containing an organic brightener additive was used. The ureylene polymers according to Formula (I) were added to said stock solution (application examples 1 to 16). [0075] A current density of 1.2 A/dm 2 was applied throughout application examples 1 to 16. The thickness of copper plated onto the top surface of the substrate was in average 12 μm. The plating time was 67 min. The test panels were cleaned, microetched and rinsed prior to electroplating of copper. [0076] The test panels used throughout application examples 1 to 16 comprised BMVs′ (depth×diameter: 80×30 μm and 100×30 μm). The size of the test panels was 12×15 mm. [0000] TABLE 1 Application examples 1 to 16 (BMV filling capability). Leveler Dimple [μm] in Dimple [μm] in Application conc. 80 × 30 μm 100 × 30 μm example Leveler additive (mg/l) BMVs{acute over ( )} BMVs{acute over ( )} 1 Preparation example 1a 3 0 3.5 2 (Preparation example 1a) 10 0 4.5 3 (Preparation example 1a) 20 0 9 4 Preparation example 1b 5 0 3 5 (Preparation example 1b) 30 0 6 6 Preparation example 2 3 0 2 7 (Preparation example 2) 10 0 3 8 (Preparation example 2) 30 0 3 9 Preparation example 3 3 0 5.5 10 (Preparation example 3) 10 0 3.5 11 (Preparation example 3) 20 0 5 12 Preparation example 4 5 0 4 13 (Preparation example 4) 30 4 8.5 14 Preparation example 5 3 0 3.5 15 (Preparation example 5) 30 0 5.5 16 Preparation example 6 3 2.5 — 17 Preparation example 7 20 7 2.4 18 Preparation example 8 10 0 3 19 (Preparation example 8) 30 0 4 20 (Preparation example 8) 50 0 2 21 Preparation example 9 5 0.3 4.8 22 (Preparation example 9) 10 0 3.8 [0077] The values observed for dimples in both 80×30 μm and 100×30 μm BMVs′ are sufficiently low. Hence, all the tested leveler additives are suitable for filling of BMVs′ with copper. [0000] Copper Deposition into TSVs′ [0078] Through-silicon vias (TSVs′) in silicon wafer substrates having a width of 6 μm and a depth of 27 μm were filled with copper using an aqueous acidic copper electrolyte comprising 55 g/l copper ions, 50 g/l sulfuric acid, 50 mg/l chloride ions, 3 ml/l of a solution containing an organic brightener additive. Soluble anodes and a Nafion® membrane separating anolyte and catholyte were used. A current density of 3 mA/cm 2 was applied to the silicon wafer substrates for 25 min in order to fill the TSVs′ with copper. [0079] A given amount of a leveler additive was added to said electrolyte in comparative application example 1 and application example 23. Comparative Application Example 1 [0080] 30 mg/l of poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea (disclosed in EP 1 069 211 A2) were added to the electrolyte prior to copper deposition. [0081] The copper filled TSVs′ obtained from this electrolyte show undesired voids in the copper deposit ( FIG. 4 ). Application example 23 [0082] 30 mg/l of the ureylene polymer according to Formula (I) obtained in preparation example 4 were added to the electrolyte prior to copper deposition. [0083] A void free filling of TSVs′ was achieved ( FIG. 5 ). The surface of the copper deposit was semi-bright and defect free.	The present invention relates to aqueous acidic plating baths for copper and copper alloy deposition in the manufacture of printed circuit boards, IC substrates, semiconducting and glass devices for electronic applications. The plating bath according to the present invention comprises copper ions, at least one acid and an ureylene polymer comprising amino residues on both termini and which is free of organically bound halogen. The plating bath is particularly useful for filling recessed structures with copper and build-up of pillar bump structures.	2
CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application Nos. 61/794,064 entitled “Heated Liquid Tapered Line Production Device and Method” filed Mar. 15, 2013, and 61/793,712 entitled “Tapered Line Production Device and Method” filed Mar. 15, 2013, the entire disclosures of which are incorporated by reference herein. FIELD Embodiments of the present invention are generally related to a tapered line production device and method and, in particular, to a device and method for efficient production of tapered fishing line through the use of heat transfer media. BACKGROUND Drawing Polyethylene (PE) fiber (a process where a thermoplastic yarn is heated and elongated to result in a stronger but thinner yarn) is a well-known process, and has been used to increase strength of fibrous materials. Drawing PE fiber allows tremendous flexibility in final product sizing, oftentimes producing different products from the same feeder stock. By changing the draw ratio during a production run, it is possible to create a tapered line that has a thick section (lower draw ratio, e.g. 1.1×) and a thinner section (higher draw ratio, e.g. 2.0×). In one example, the thick portion of the taper is 50% stronger than the thin portion. The purpose of the thicker, stronger section is to have enough strength to offset the reduction due to making a knot. A good knot in 80 lb line breaks around 50 lbs. By creating a line with 80 lbs in a thicker section (designated for knot tying), and then tapering down to 50 lbs in the thinner section, one creates a line that has the same load carrying performance as an all 80 lb line, yet with increased capacity on the reel (and reduced drag in the water) because the line is not all at the thicker diameter. The thick/thin section may repeat, for example, every 25 feet to allow anglers to cut off only 25 feet each time they exhaust the thicker knot section of the line. Production rates are affected by dwell time in heat transfer media. For example, if it takes 20 seconds to heat and draw braid to a desired ratio, the longer the “oven” (or heat transfer device) the faster the output. Here, the word “oven” indicates an intuitive concept of any heat transfer media. A double length of oven will allow double output speed at a given temperature. However, the draw happens throughout the length of the oven, so as long as one is making a constant diameter product there is no production penalty. In the specific case of a tapered line of the invention, it is desired to taper from the thin portion to the thicker portion of the line within a short period or length. This requires a short oven to localize the taper. However, the throughput cost of such a short oven may be 10× slower than the regular process due to long dwell time, thus resulting in a cost-prohibitive process. With the invention herein disclosed, a reduced processing time to between 2× to 3× is achieved. Therefore, there is a long-felt need for a production device and method that can efficiently and effectively yield a tapered line of varying thickness. The present device and method of operation addresses and solves these needs. The present invention relates to a device and method for efficient production of tapered fishing line through the use of heat transfer media. The device and method allow, among other things, a means to create tapered fishing line with minimal transitional distances between tapered sections and may operate at higher rates of production than conventionally provided. By way of providing additional background and context, the following reference is incorporated by reference in its entirety for the purpose of explaining various methods of tapering fishing lines: U.S. Pat. No. 7,081,298 to Nakanishi. SUMMARY It is one aspect of the present invention to provide a programmable, movable trolley assembly that allows for relatively quick and drastic draw ratio changes in line, such as braided superline, without negatively impacting processing speeds is disclosed. The trolley interfaces with the line at the point of entry into the heat transfer media. Nominal thickness line is produced at a nominal draw ratio by passing line through a heat transfer media. The line enters the upper portion of a trolley device positioned proximal the heat transfer media. The line then is routed to a lower portion of the trolley where it is immersed in the heat transfer media. The line exits the heat transfer media having been stretched or drawn to a thinner diameter. During this process, the trolley is stationary at a first or entry end of the heat transfer media. To produce a line portion which is relatively thicker than the nominal thickness line, the trolley moves with the line from the first or entry end of the heat transfer media toward the second or exit end of the heat transfer media. The trolley travels down all or some of the length of the heat transfer media with the line at the desired point of draw ratio decrease to delay entry of any new length of braid into the heat transfer media. The trolley also allows the length of braid already in the tank to continue to be drawn to its maximum length. The trolley then stops at a pre-determined point along the heat transfer media length (which may include the second or exit end of the heat transfer media) to allow un-drawn material to enter a shorter length of heat transfer media, thus experiencing a shorter draw rate (and thus produce a relatively thicker diameter line). The trolley then returns to its original location to repeat the process. In this way, a line with variable thickness is produced. Stated another way: Step 1: The braided line running on the machine is run through the full length of heat transfer media and stretched to the maximum desired elongation ratio at the maximum preferred input speed. Step 2: When the point of the braid where the desired decreased draw ratio length is located begins to pass through the trolley device and into the heat transfer media (located at the input end of the heat transfer media), the trolley begins to move through the heat transfer media at the exact input speed of the braid until it reaches the desired location along the heat transfer media length. At the same time, the output speed of the rollers retrieving the braid out of the heat transfer media begins to decrease to the desired low-draw ratio speed at a rate equal to that of the travel time of the interface device. Step 3: A length of braid enters the heat transfer media and is exposed to a shorter length of heat transfer media and drawn to its desired smaller draw ratio using the same preferred input speed as in Step 1. Step 4: When the point of the braid where the desired draw ratio increase is located begins to pass through the trolley (now located toward the output side of the heat transfer media), the trolley begins to move through the heat transfer media at the maximum speed possible to its original position at the input end of the heat transfer media. At the same time, the output speed of the rollers retrieving the braid out of the heat transfer media begins to increase up to the original maximum-draw speed at a rate equal to that of the travel time of the interface device. Step 5: Repeat, i.e. return to Step 1. In one embodiment of the invention, a tapered line production device is disclosed, the tapered line production device comprising: a body having a first side, a second side, and a heat transfer assembly positioned therein, the heat transfer assembly adapted to selectively provide thermal energy to a line passing through the heat transfer assembly from the first side to the second side; an input roller operating at a first rate that delivers line to the first side; an output roller operating at a nominal second rate that receives line from the second side; and a moveable trolley assembly engaged with the body, the trolley assembly configured to controllably position the line to selectively engage or not engage with the heat transfer assembly. In another embodiment of the invention, a method of producing tapered line is disclosed, the method comprising: providing a device having a body with a first side, a second side, and a heat transfer assembly positioned therein, the heat transfer assembly adapted to selectively provide thermal energy to a line passing through the heat transfer assembly between the first side to the second side; providing a moveable trolley assembly engaged with the body, the trolley assembly configured to controllably position the line to selectively engage or not engage with the heat transfer assembly; receiving the line at the first side by an input roller operating at a first rate; passing the line through the heat transfer assembly so as to elongate the line; outputting a first portion of the line from the second side by an output roller operating at a nominal second rate wherein the first portion of the line has a first diameter; moving the trolley assembly from the first side to the second side at a first speed approximately equal to the first rate wherein the line does not pass through the heat transfer assembly; operating the output roller at a decreasing rate from the nominal second rate to approximately the first rate as the trolley traverses the length of the body from the first side to the second side; outputting a second portion of the line from the second side wherein the second portion of the line has a second diameter larger than the first diameter; wherein a tapered line is produced. In one aspect of the invention, the device and/or method further comprises a controller, which may comprise a Programmable Logic Controller, which controls at least one of the input roller, output roller and trolley. In one embodiment of the invention, the nominal second rate of the output roller is greater than the first rate of the first roller. In another aspect of the invention, the trolley is configured to traverse at least a portion of the length of the body from the first side to the second side at a first speed, and/or wherein the first speed may be approximately the speed of the line delivered to the first side, and/or wherein as the trolley traverses the length of the body from the first side to the second side, the output roller decreases from the nominal second rate to approximately the first rate and/or wherein the trolley is configured to traverse the length of the body from the second side to the first side at a second speed, and/or a plurality of lines are delivered to the first side. In another aspect of the invention, the line comprises polyethylene, and/or the heat transfer media is a resin bath, and/or the first speed is selectable by a user. In one embodiment of the invention, as the trolley traverses the length of the body from the first side to the second side, the nominal second rate of the output roller remains constant while the first rate of the input roller varies. In another embodiment of the invention, as the trolley traverses the length of the body from the first side to the second side, the nominal second rate of the output roller varies and the first rate of the input roller varies. In another embodiment of the invention, a tapered line production system is disclosed, the method comprising: a body having a first side, a second side, and a heat transfer assembly positioned therein, the heat transfer assembly adapted to selectively provide thermal energy to a line passing through the heat transfer assembly from the first side to the second side; an input roller operating at a first rate that delivers line to the first side; an output roller operating at a nominal second rate that receives line from the second side, the nominal second rate greater than the first rate; a moveable trolley assembly engaged with the body, the trolley assembly configured to controllably position the line to selectively engage or not engage with the heat transfer assembly while the trolley traverses at least a portion of the body from the first side to the second side at a first speed; and a controller which controls at least one of the input roller, output roller and trolley; wherein the first speed is approximately the speed of the line delivered to the first side; wherein as the trolley traverses the length of the body from the first side to the second side, the output roller decreases from the nominal second rate to approximately the first rate; wherein the line comprises polyethylene, fluorocarbon, nylon, olefins, polyester, and thermoplastic and is configured as at least one of monofilament, co-filament, multi-filament, twisted, braided, thermally-fused and chemically-fused line; and wherein the heat transfer media is a resin bath. The term “automatic” and variations thereof, as used herein, refers to any process or operation done without material human input when the process or operation is performed. However, a process or operation can be automatic, even though performance of the process or operation uses material or immaterial human input, if the input is received before performance of the process or operation. Human input is deemed to be material if such input influences how the process or operation will be performed. Human input that consents to the performance of the process or operation is not deemed to be “material.” The terms “determine”, “calculate” and “compute,” and variations thereof, as used herein, are used interchangeably and include any type of methodology, process, mathematical operation or technique. The term “line” or “braided line” shall mean any cord that has elastic properties and may be stretched, without breaking, such as by a source of thermal energy. Line shall include, without limitation, fishing lines and lines comprising polyethylene, fluorocarbon, nylon, olefins, polyester, and other thermoplastic materials in multi-filament or monofilament forms. Line shall include, without limitation, twisted, braided, co-filament, monofilament and thermally-fused or chemically-fused lines (also known as “superlines”). The term “resin” shall mean any liquid substance that will set into a solid substance, to include, without limitation, synthetic or natural or organic resins. It shall be understood that the term “means” as used herein shall be given its broadest possible interpretation in accordance with 35 U.S.C., Section 112, Paragraph 6. Accordingly, a claim incorporating the term “means” shall cover all structures, materials, or acts set forth herein, and all of the equivalents thereof. Further, the structures, materials or acts and the equivalents thereof shall include all those described in the summary of the invention, brief description of the drawings, detailed description, abstract, and claims themselves. It is important to note that the transition length from long draw ratio to short draw ratio or short draw ratio to long draw ratio is directly related to the length of braid in the heat transfer media at the time of draw ratio transition. To achieve a short transition length the braid length exposed in the heat transfer media must be short. Alternately, the shorter the braid length in the heat transfer media, the lower the processing speed. The movable trolley allows one to maximize processing speed and minimize the transition lengths by adjusting the braid length in the heat transfer media depending on process step. One of ordinary skill in the art will appreciate that embodiments of the present disclosure may be constructed of materials known to provide, or predictably manufactured to provide the various aspects of the present disclosure. These materials may include, for example, stainless steel, titanium alloy, aluminum alloy, chromium alloy, and other metals or metal alloys. These materials may also include, for example, carbon fiber, ABS plastic, polyurethane, and other fiber-encased resinous materials, synthetic materials, polymers, and natural materials. This Summary of the Invention is neither intended nor should it be construed as being representative of the full extent and scope of the present disclosure. The present disclosure is set forth in various levels of detail in the Summary of the Invention as well as in the attached drawings and the Detailed Description of the Invention, and no limitation as to the scope of the present disclosure is intended by either the inclusion or non-inclusion of elements, components, etc. in this Summary of the Invention. Additional aspects of the present disclosure will become more readily apparent from the Detailed Description, particularly when taken together with the drawings. The above-described benefits, embodiments, and/or characterizations are not necessarily complete or exhaustive, and in particular, as to the patentable subject matter disclosed herein. Other benefits, embodiments, and/or characterizations of the present disclosure are possible utilizing, alone or in combination, as set forth above and/or described in the accompanying figures and/or in the description herein below. However, the Detailed Description of the Invention, the drawing figures, and the exemplary claims set forth herein, taken in conjunction with this Summary, define the invention. As used herein, “at least one”, “one or more”, and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the general description of the invention given above, and the detailed description of the drawings given below, serve to explain the principals of this invention. FIG. 1 depicts a schematic representation of the device of the invention in one preferred embodiment; FIG. 2 is a cut-away side-view of a representation of a portion of the device in one preferred embodiment; FIGS. 3A-H are schematic representations of various states of the device in one embodiment; FIGS. 4A-C are an example construction of a portion of the device in one preferred embodiment; and FIG. 5 is an example construction of a portion of the device in one preferred embodiment. This figure is to scale. It should be understood that the drawings are not necessarily to scale. In certain instances, details that are not necessary for an understanding of the invention or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein. DETAILED DESCRIPTION FIGS. 1-5 show various embodiments of the Device 100 of the present invention. FIGS. 1 and 2 depict schematic representations of the Device 100 of the invention in one preferred embodiment. Generally, the Device 100 comprises a Feeder Stock Spool 110 , which provides raw braid Line 102 to the Device 100 . The Line 102 unwinds and travels along the direction of the arrows shown, i.e. generally right to left. The Line 102 travels through two consecutive Loop One 112 and Loop Two 114 . In other embodiments of the invention, no such loops are employed, or a different number of such loops are employed, such as one or a plurality of loops. The Line 102 then travels to Input Roller 120 which is in communication with Controller 200 . The Controller 200 also may be in communication with one or more of the Output Roller 180 , Trolley 160 , and Heat Transfer Assembly 140 . The Controller 200 may be a Programmable Logic Control (PLC) or any controller known to those skilled in the art. For example, any digital or analog control that may, among other things, comprise controlling the speed (RPM) of the Input Roller 120 , the speed (RPM) of the Output Roller 180 , positioning (to include speed) of the Trolley 160 , and thermal parameters (such as temperature) of the Heat Transfer Assembly 140 . After engaging the Input Roller 120 , the Line 102 engages Roller One 122 , Roller Two 124 and Roller Three 126 . In other embodiments of the invention, no such rollers are employed, or a different number of such rollers are employed, such as one or a plurality of rollers. Line 102 continues in a generally right to left direction to optionally engage one or more inking stations. FIG. 1 depicts Line 102 engaging a sequence of Inking Station One 132 , Inking Station Two 134 and Inking Station 136 . The Line 102 is colored or inked during engagement with the one or more inking stations. The Line 102 then enters the Heat Transfer Assembly 140 , comprising a Heat Transfer Assembly First End 141 with Heat Transfer Assembly Line Input End 142 (where Line 102 enters the Heat Transfer Assembly 140 ), and Heat Transfer Assembly Second End 143 with Heat Transfer Assembly Line Output End 144 (where Line 102 exits the Heat Transfer Assembly 140 ). Within the Heat Transfer Assembly 140 the Line 102 engages the Trolley 160 and may pass through a portion of the Heat Transfer Volume 150 comprising a Heat Transfer Volume Upper End 152 . Upon exiting the Heat Transfer Assembly 140 , the former Line 102 , having passed through the Heat Transfer Assembly 140 , is deemed Finished Line 104 . The Finished Line 104 optionally engages Roller Four 174 before engaging Output Roller 180 . Output Roller 180 , by adjusting its rotational speed (that is RPM), generally determines the amount of time a particular portion of Line 102 will remain within Heat Transfer Assembly 140 , which determines the diametrical thickness of Finished Line 104 . A tapered product will have Finished Line 104 of varying thickness, e.g. thick to thin to thick. After engaging Output Roller 180 , Finished Line 104 may optionally engage one or more of Roller Five 182 , Roller Six 184 and Loop Three 186 before engaging Take-up Reel or Spool 190 . The Finished Line 104 is gathered at Take-up Reel 190 . In one embodiment, the Take-up Reel 190 comprises a clutch mechanism. In one embodiment, the Input Roller 120 and Roller One 122 are an integrated assembly in which Line 102 winds around both elements before continuing downstream of the Device 100 (i.e. generally right to left and toward the Heat Transfer Assembly 140 ). More specifically, the Input Roller 120 and Roller One 122 are an integrated assembly commonly called a Godet Roller by one skilled in the art. A Godet Roller enables, among other things, tension to be applied to the assembly of Input Roller 120 and Roller One 122 without imparting tension upstream, e.g. to the Stock Spool 110 . Similarly, in one embodiment, the Output Roller 180 and Roller Five 182 are an integrated assembly in which Line 104 winds around both elements before continuing downstream of the Device 100 (i.e. generally right to left and toward the Take-up Reel 190 ). More specifically, the Output Roller 180 and Roller Five 182 are an integrated assembly such as a Godet Roller. The device 100 comprises a Controller Display 210 and a Motor 220 . In one embodiment, the Motor 220 is a DC motor, although any means of driving one or more of the Input Roller 120 , Output Roller 180 , and Trolley 160 may be employed. Specifically as depicted in FIG. 2 , Trolley 160 comprises a Trolley Upper Wheel 162 which receives Line 102 through Heat Transfer Assembly Line Input End 142 and routes the line to Trolley Lower Wheel 164 before directing the line out of Heat Transfer Assembly 140 via Heat Transfer Assembly Line Output End 144 . Note that the line leaving Trolley Lower Wheel 164 is below the Heat Transfer Volume Upper End 152 and therefore is contained within the Heat Transfer Volume 150 . Trolley 160 may be driven within the Heat Transfer Assembly 140 by any means known to those skilled in the art, to include one or more rails. For example, two linear rails may be employed as shown in FIG. 2 as Trolley Lower Rail Assembly 166 and Trolley Lower Rail Assembly 167 . The Heat Transfer Assembly 140 may be any means known to those skilled in the art to provide thermal transfer, to include ovens such as convection ovens, liquids, and gases to include heated air. In one embodiment, the Heat Transfer Assembly 140 may comprise heated surfaces, such as heated rollers, which engage the line. In one preferred embodiment, the Heat Transfer Assembly 140 operates between approximately 120 degree and 180 degree Celsius. In a more preferred embodiment, Heat Transfer Assembly 140 operates between approximately 130 degree and 170 degree Celsius. In another preferred embodiment, the Heat Transfer Assembly 140 operates at approximately 150 degree Celsius. In one embodiment, the Heat Transfer Assembly 140 comprises a plurality of individually-controlled heat or temperature zones. The temperature zones may be any combination of multiple horizontally-spaced or separated temperature zones or vertically-spaced or separated temperature zones. Such zones, among other things, create different draw ratios for line immersed therein, thereby creating different relative line thicknesses. In one embodiment, the Heat Transfer Assembly 140 is a resin bath, such as a wax bath or wax resin bath. Referring to FIGS. 3A-H , a schematic representation of various states of the Device 100 is provided. Generally, Line 102 travels from Input Roller 120 into Heat Transfer Assembly 140 and to Output Roller 180 . Within the Heat Transfer Assembly 140 , Line 102 engages Trolley 160 and may engage (i.e. pass through) a portion of Heat Transfer Volume 150 . The amount of time a given portion of Line 102 engages the Heat Transfer Volume 150 (i.e. the “dwell time) determines the potential relative thickness of the diameter of Line 102 . A portion of Line 102 engaging a greater amount of Heat Transfer Volume 150 (i.e. a Line 102 with a relatively longer or greater dwell time) may become more elongated (drawn farther) and thus thinner than a portion of Line 102 that engages the same Heat Transfer Volume 150 for a shorter amount of time (ie. a shorter or smaller dwell time with less draw potential). The device 100 allows a given input Line 102 to receive differing dwell times and therefore result in a Line 102 of differing elongation or diametrical thickness. A sequence of sequential states D N of the Device 100 is provided in FIGS. 3A-H , where N=1 through 8. Also shown in FIGS. 3A-H are states T N of the Trolley 160 and states O N of the Output Roller 180 . Input Roller 120 typically operates at a constant speed. Device State D 1 ( FIG. 3A ) T 1 : Trolley 160 stationary at Heat Transfer Assembly First End 141 O 1 : Output Roller 180 operating at a constant, maximum preferred speed (e.g. O MAX ) Line Engaged with Heat Transfer Assembly 102 ′ being elongated to maximum elongation (thus becoming thinner relative to input Line 102 upstream of Heat Transfer Assembly 140 ) Device State D 2 ( FIG. 3B ) T 2 : Trolley 160 departs from Heat Transfer Assembly First End 141 at speed T SET (i.e. begins to move from right to left) O 2 : Output Roller 180 begins to decrease in rotational speed (i.e. RPM) from the maximum preferred speed (i.e. O MAX ); rate of speed decrease is approximately determined by Trolley travel time from Heat Transfer Assembly First End 141 to Heat Transfer Assembly Second End 143 Line Engaged with Heat Transfer Assembly 102 ′ being elongated to maximum elongation (thus becoming relatively thinner) Device State D 3 ( FIG. 3C ) T 3 : Trolley 160 continues away from Heat Transfer Assembly First End 141 at speed T SET O 3 : Output Roller 180 continues to decrease in speed from the maximum preferred speed (i.e. O MAX ); rate of speed decrease is approximately determined by Trolley travel time from Heat Transfer Assembly First End 141 to Heat Transfer Assembly Second End 143 Line Engaged with Heat Transfer Assembly 102 ′ being elongated to maximum elongation (thus becoming relatively thinner) Line Affixed Atop Trolley 102 ″ is not engaged with Heat Transfer Assembly 140 and thus is not undergoing elongation (thus remaining at its nominal diameter and thus relatively thicker with respect to Line Engaged with Heat Transfer Assembly 102 ′) Device State D 4 ( FIG. 3D ) T 4 : Trolley 160 reaches Heat Transfer Assembly Second End 143 O 4 : Output Roller 180 reaches minimum preferred speed (i.e. O MIN ) All of Line Affixed Atop Trolley 102 ″, spanning length of Heat Transfer Assembly 140 , remains atop Trolley 160 and none of Line Atop Trolley 102 ″ has engaged with Heat Transfer Assembly 140 and thus is not elongated (thus remaining at its nominal diameter and thus relatively thicker with respect to Line Engaged with Heat Transfer Assembly 102 ′) Device State D 5 ( FIG. 3E ) T 5 : Trolley 160 momentarily stops at Heat Transfer Assembly Second End 143 O 5 : Output Roller 180 now operating at steady minimum preferred speed (i.e. O MIN ) All of Line Affixed Atop Trolley 102 ″, spanning length of Heat Transfer Assembly 140 , remains atop Trolley 150 and none of Line Atop Trolley 102 ″ has engaged with Heat Transfer Assembly 140 and thus is not elongated (thus remaining at its nominal diameter and thus relatively thicker with respect to Line Engaged with Heat Transfer Assembly 102 ′) Device State D 6 ( FIG. 3F ) T 6 : Trolley 160 departs Heat Transfer Assembly Second End 143 at speed T RETURN toward Heat Transfer Assembly First End 141 (i.e. begins to move left to right) O 6 : Output Roller 180 begins to accelerate from minimum preferred speed (i.e. O MIN ) Former Line Affixed Atop Trolley 102 ′″ begins to engage with Heat Transfer Assembly 140 and thus begins to undergo elongation proportional to dwell time of particular portion of Former Line Atop Trolley 102 ′″ Device State D 7 ( FIG. 3G ) T 7 : Trolley 160 continues toward Heat Transfer Assembly First End 141 at speed T RETURN O 7 : Output Roller 180 continues to accelerate from minimum preferred speed (i.e. O MIN ) to maximum preferred speed (i.e. O MAX ) Former Line Atop Trolley 102 ′″ continues to engage with Heat Transfer Assembly 140 and continues to undergo elongation proportional to dwell time of particular portion of Former Line Atop Trolley 102 ′″ Device State D 8 ( FIG. 3H ) T 8 : Trolley 160 arrives at Heat Transfer Assembly First End 141 O 8 : Output Roller 180 reaches maximum preferred speed (i.e. O MAX ) End of Former Line Atop Trolley 102 ′″ reaches Heat Transfer Assembly Second End 143 ; all line upstream (i.e. to the right) of Former Line Affixed Atop Trolley 102 ′″ will be Line Engaged with Heat Transfer Assembly 102 ′ (Trolley 160 idles, i.e. remains stationary, at Heat Transfer Assembly First End 141 for Trolley Idle Time T IDLE —this is Device State 1—thus beginning a new cycle of Device States D 1 → 8 ) FIGS. 4A-C are an example construction of a portion of the device in one preferred embodiment. This figure is to scale; all dimensions are in inches. FIG. 5 is an example construction of a portion of the device in one preferred embodiment. This figure is to scale. The invention may use other than polyethylene (PE) fiber as a line. For example, any linearly oriented polymeric structure, braided, twisted or otherwise constructed linear fibrous assembly, thermally fused line, monofilament and those lines known to one skilled in the art that may be manipulated through application of thermal energy, to include manipulation such as tapering, may be used. In another embodiment, rather than decreasing the rate of the output roller from the nominal second rate to approximately the first rate as the trolley traverses the length of the body from the first side to the second side, the same relative change in rate (and thus yielding the same tapered effect) between the input and output rollers is achieved by varying one or both of the input and output rollers. That is, in one embodiment of the invention, when the Trolley 160 traverses the length of the Heat Transfer Assembly 140 from the first side to the second side, the second rate of the Output Roller 180 remains constant while the first rate of the Input Roller 120 varies. In another embodiment of the invention, when the Trolley 160 traverses the length of the Heat Transfer Assembly 140 from the first side to the second side, the second rate of the Output Roller 180 varies and the first rate of the Input Roller 120 also varies. In one embodiment, one or more computers are used to control, among other things, the RPM (rate) of the input roller, the RPM (rate) of the output roller, the movement and positioning of the trolley, the temperature of the heat transfer assembly, and the RPM (rate) of the stock spool. In one embodiment, a user selectively inputs one or more of the RPM of the input roller, the RPM of the output roller, the movement and positioning of the trolley, the temperature of the heat transfer assembly, and the RPM of the stock spool. The user may engage with device and/or controller through a display. The term “display” refers to a portion of one or more screens used to display the output of a computer to a user. A display may be a single-screen display or a multi-screen display, referred to as a composite display. A composite display can encompass the touch sensitive display of one or more screens. A single physical screen can include multiple displays that are managed as separate logical displays. Thus, different content can be displayed on the separate displays although part of the same physical screen. A display may have the capability to record and/or print display presentations and display content, such as reports. In one embodiment, the user interacts with the computer through any means known to those skilled in the art, to include a keyboard and/or display to include a touch-screen display. The term “computer-readable medium” as used herein refers to any tangible storage and/or transmission medium that participate in providing instructions to a processor for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, NVRAM, or magnetic or optical disks. Volatile media includes dynamic memory, such as main memory. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, magneto-optical medium, a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, a solid state medium like a memory card, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. A digital file attachment to e-mail or other self-contained information archive or set of archives is considered a distribution medium equivalent to a tangible storage medium. When the computer-readable media is configured as a database, it is to be understood that the database may be any type of database, such as relational, hierarchical, object-oriented, and/or the like. Accordingly, the disclosure is considered to include a tangible storage medium or distribution medium and prior art-recognized equivalents and successor media, in which the software implementations of the present disclosure are stored. Computer processing may include any known to those skilled in the art, to include desktop personal computers, laptops, mainframe computers, mobile devices and other computational devices. In yet another embodiment, the disclosed systems and methods may be partially implemented in software that can be stored on a storage medium to include a computer-readable medium, executed on programmed general-purpose computer with the cooperation of a controller and memory, a special purpose computer, a microprocessor, or the like. In these instances, the systems and methods of this disclosure can be implemented as program embedded on personal computer such as an applet, JAVA® or CGI script, as a resource residing on a server or computer workstation, as a routine embedded in a dedicated measurement system, system component, or the like. The system can also be implemented by physically incorporating the system and/or method into a software and/or hardware system. Communications means and protocols, such as those used to communicate between a user display and controller, may include any known to those skilled in the art, to include cellular telephony, internet and other data network means such as satellite communications and local area networks. As examples, the cellular telephony can comprise a GSM, CDMA, FDMA and/or analog cellular telephony transceiver capable of supporting voice, multimedia and/or data transfers over a cellular network. Alternatively or in addition, other wireless communications means may comprise a Wi-Fi, BLUETOOTH™, WiMax, infrared, or other wireless communications link. Cellular telephony and the other wireless communications can each be associated with a shared or a dedicated antenna. Data input/output and associated ports may be included to support communications over wired networks or links, for example with other communication devices, server devices, and/or peripheral devices. Examples of input/output means include an Ethernet port, a Universal Serial Bus (USB) port, Institute of Electrical and Electronics Engineers (IEEE) 1394, or other interface. Communications between various components can be carried by one or more buses. As will be appreciated, it would be possible to provide for some features of the inventions without providing others. The present invention, in various embodiments, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, sub-combinations, and subsets thereof. Those of skill in the art will understand how to make and use the present invention after understanding the present disclosure. The present invention, in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, for example for improving performance, achieving ease and/or reducing cost of implementation. The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention. Moreover though the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter. For example, the steps may be performed in any order and are not limited to the particular ordering discussed herein. Reference No. Component 100 Device 102 Line 102′ Line Engaged with Heat Transfer Assembly 102″ Line Affixed Atop Trolley 102′″ Former Line Affixed Atop Trolley 104 Finished Line 110 Feeder Stock Spool 112 Loop One 114 Loop Two 120 Input Roller 122 Roller One 124 Roller Two 126 Roller Three 132 Inking Station One 134 Inking Station Two 136 Inking Station Three 140 Heat Transfer Assembly 141 Heat Transfer Assembly First End 142 Heat Transfer Assembly Line Input End 143 Heat Transfer Assembly Second End 144 Heat Transfer Assembly Line Output End 150 Heat Transfer Volume 152 Heat Transfer Volume Upper End 160 Trolley 162 Trolley Upper Wheel 164 Trolley Lower Wheel 166 Trolley Upper Rail Assembly 167 Trolley Lower Rail Assembly 174 Roller Four 180 Output Roller 182 Roller Five 184 Roller Six 186 Loop Three 190 Take-up Reel 200 Controller 210 Controller Display 220 Motor D N Device State N T IDLE Trolley Idle Time T N Trolley State N T RETURN Trolley Return Speed T SET Trolley Set Speed O N Output Roller State N O MIN Output Roller Minimum Speed O MAX Output Roller Maximum Speed	The present invention provides a tapered line production device and method for efficiently producing line of varying thickness. An additional aspect of the present invention is to employ a heat transfer media to provide a tapered fishing line production device and method that operates at high rates of production. Further, the device may be configured to create tapered fishing line with minimal transitional distances between tapered sections.	3
BACKGROUND [0001] The present invention generally relates to the field of particulate filtration assemblies and, more particularly, to systems for cleaning filters within such assemblies. [0002] Particulate filtration assemblies function to remove contaminates from the air or other fluid medium. One type of particulate filtration assembly is a dust collector for filtering dust particles out of the air. Dust collectors mainly use a filter media, such as a filter bag, to trap dust particles and allow cleaned air to pass through the filter. Over time the trapped dust particles build up a dust cake on the upstream side (e.g, outside) of the filter media, greatly reducing the efficiency of the dust collector. [0003] Dust collectors typically include a system for cleaning the filter media when it gets clogged with particulate. Such cleaning systems commonly are designed to shoot or force pressurized pulses of air into the opening of the filter media from downstream (e.g., inside) of the media. The air is often forced through a cleaning nozzle that accelerates the air to supersonic speeds prior to being forced toward the filter media. The cleaning air momentarily flows through and agitates the filter media by reversing the oncoming fan air, resulting in particulate dislodging and falling into a particulate removal system, such as a hopper. [0004] Cleaning systems for dust collectors commonly utilize a single blowpipe for providing compressed air to multiple (e.g., as many as sixteen) nozzles. Each nozzle is positioned to provide high-velocity air to a corresponding filter media. As pressurized air is provided to one end of the blowpipe from a manifold, all nozzles attached to the blowpipe will function to direct air to all corresponding filter media. SUMMARY [0005] When pressurized air is provided from the manifold to one end of the blowpipe, the pressure pulse travels the length of the blowpipe until it contacts the opposing, closed end of the blowpipe. At that time, the pressure in the blowpipe quickly builds, starting at the closed end of the blowpipe and progressing back toward the manifold. As the pressurized air travels the length of the blowpipe and sequentially provides pressurized air to the nozzles, the pressure of the air reduces slightly. As a result, the pressure provided to the nozzle closest to the manifold is slightly less than the pressure provided to the nozzle farthest from the manifold. This results in a difference in performance of the various nozzles positioned on the same blowpipe. This phenomenon is illustrated in FIG. 7 , which shows the pressure at three different nozzles after providing 100 psig air from the manifold to the blow pipe. After an initial period of time of about 0.074 seconds, the pressure at the nozzle farthest from the manifold is higher than the pressure of the nozzle closest to the manifold, and remains that way until the pressures have subsided. These test results show that there is a pressure differential of about 9.5% between the nearest and farthest nozzles. [0006] The present invention recognizes this phenomenon and modifies the nozzles accordingly in order to reduce the difference in performance of nozzles positioned on the same blowpipe. More specifically, the present invention provides a particulate filtration device comprising filter media having an upstream surface and a downstream surface, a gas-moving device for moving gas through the filter media from the upstream surface toward the downstream surface, and a cleaning assembly including a blow pipe having a plurality of cleaning nozzles for directing a flow of cleaning gas toward the filter media. A first one (e.g., a plurality) of the cleaning nozzles comprises a structural characteristic (e.g., throat size, exit angle, exit size) that is different than a second one (e.g., a plurality) of the cleaning nozzles. [0007] In one embodiment, the filter media comprises a filter bag corresponding with each nozzle, and both the first one and the second one of the cleaning nozzles are spaced substantially the same distance from the corresponding filter bag. The cleaning assembly can also include a plurality of blow pipes (e.g., each having a plurality of cleaning nozzles) coupled to a gas-pressurized manifold, and a valve positioned between the manifold and each blow pipe to control gas flowing from the manifold to the blow pipes. In this configuration, it is preferred that the nozzle nearer the manifold has a larger throat size, smaller exit angle, and larger exit size than the nozzle farther from the manifold. [0008] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a cut-away perspective view of a particulate filtration device embodying the present invention. [0010] FIG. 2 is an enlarged partial view of the device of FIG. 1 during a cleaning operation. [0011] FIG. 3 is a partially cut-away end view of another particulate filtration device embodying the present invention and having more filter bags. [0012] FIG. 4 is a section view taken along line 4 - 4 in FIG. 3 . [0013] FIG. 5 is a section view taken along line 5 - 5 in FIG. 4 . [0014] FIG. 6 is an enlarged section view of a nozzle used in the embodiment of FIG. 5 . [0015] FIG. 7 is a chart that illustrates the phenomenon described in the Summary. DETAILED DESCRIPTION [0016] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. [0017] FIGS. 1 and 2 illustrate a particulate filtration system, which in the preferred embodiment is a dust collector 10 designed to remove particulates 14 , such as dust, from the air. The illustrated dust collector 10 includes a support assembly 18 , a particulate removal assembly 22 positioned within the support assembly 18 , a filtering assembly 26 positioned on top of the support assembly 18 , and a cleaning assembly 30 positioned on top of the filtering assembly 26 . [0018] The illustrated support assembly 18 includes support members 34 that provide a rigid frame to which the remaining assemblies may be mounted. The illustrated support assembly 18 is generally square-shaped, and the support members 34 include four legs positioned at the four corners of the square and diagonal braces that provide extra rigidity to the frame. In other constructions, the support assembly 18 may be different shapes and may have more or less support members 34 of the same or different shape. In addition, more than four or less than four legs are conceivable. [0019] The illustrated particulate removal assembly 22 is positioned within the support assembly 18 and is attached to the filter assembly 26 such that the particulate removal assembly 22 receives the particulates 14 that are removed from the air by the filter assembly 26 . The particulate removal assembly 22 includes a door (not shown) and a hopper 36 with a generally conical shape that funnels the particulates 14 into a container (not shown). The door is positioned in the hopper 36 and is movable between an open position and a closed position. While in the closed position, the particulate removal assembly 22 inhibits air flow out of the particulate removal assembly 22 and collects the particulates 14 that are removed from the air by the filter assembly 26 . In the open position, the particulate removal assembly 22 allows the collected particulates 14 to escape the hopper 36 and be emptied into a container for disposal. In other constructions, the particulate removal assembly may have other arrangements. For example, the hopper 36 may have a different profile and the door may be replaced with a powered louver. Other arrangements are also conceivable and are known by those skilled in the art. [0020] The illustrated filter assembly 26 is positioned above the particulate removal assembly 22 and mounted on top of the support assembly 18 . The filter assembly 26 includes an intake 38 , a screen 40 covering the intake 38 and promoting an equal distribution of airflow in the filter and preventing large objects from entering the filter assembly 26 , a classifier section 42 , filter media 43 (e.g. filter bags), and a filter assembly enclosure 44 , which includes four vertical walls, and a top 46 , commonly referred to as a “tubesheet”. The bottom of the filter assembly 26 is open to provide access to the particulate removal assembly 22 such that the particulates 14 collected in the filter assembly 26 are allowed to fall into the particulate removal assembly 22 . The classifier section 42 is a space between the filter assembly enclosure 44 adjacent the screen 40 and the filter media 43 closest to the screen 40 . The classifier section 42 is illustrated as an empty space and provides an area for larger particulates 14 to drop out of the air thereby reducing the load on the filter media 43 . In addition, baffles could be added to the classifier section 42 to further remove particulates 14 . The top 46 defines one or more openings 54 aligned with the filter media 43 and through which filtered air can flow out of the filter assembly 26 and into the cleaning assembly 30 . To escape the filter assembly 26 , the air must pass through the filter media 43 to gain access to the openings 54 and pass into the cleaning assembly 30 . A fan 56 moves air through the dust collector 10 . In other constructions, different filter media 43 may be used and the filter assembly may be arranged differently as is known by those skilled in the art. For example, the classifier section may have a different arrangement or may be removed. [0021] The illustrated cleaning assembly 30 is positioned on top of the filter assembly 26 and includes a cleaning assembly enclosure 58 , an exhaust 62 , and an advanced cleaning system 66 . The cleaning assembly enclosure 58 includes four vertical walls and a top. The illustrated exhaust 62 is attached to the side of the cleaning assembly enclosure 58 and directs cleaned air out of the dust collector 10 . In other constructions, the exhaust 62 may be arranged differently and may be attached to a different side of the cleaning assembly enclosure 58 . [0022] As is best seen in FIG. 2 , the advanced cleaning system 66 includes a primary distribution member 70 , one or more secondary distribution members in the form of blowpipes 74 attached to the primary distribution member 70 , and one or more nozzles 110 coupled to the blowpipes 74 . The primary distribution member 70 distributes bursts of pressurized air to the blowpipes 74 , which in turn supply the nozzles 110 with bursts of pressurized air. As the pressurized air passes through the nozzles 110 , it is directed into a stream of cleaning air 114 which is directed into the openings 54 and downward though the filter media 43 . [0023] In operation, air including particulates 14 enters the filtration assembly 26 of the dust collector 10 through the intake 38 where the screen 40 inhibits large particulates 14 from entering the filter assembly enclosure 44 . Once inside the filter assembly enclosure 44 the air moves in a “downflow” air pattern toward the filter media 43 . First, the air will pass through the classifier section 42 where more particulates 14 will drop out. After the classifier section 42 , the air enters into contact with the filter media 43 , and the remaining particulates 14 are trapped on the filter media 43 before the clean air exits through the openings 54 and enters the cleaning assembly 30 and exits the dust collector 10 . [0024] The filtering assembly 26 provides several advantages due to the “downflow” air pattern, the geometry of the openings 54 , and other features not mentioned. The “downflow” air pattern guides the particulates 14 down to the bottom of the filter assembly 26 and into the particulate removal assembly 22 . This causes more particulates 14 to fall out in the classifier section 42 and fewer particulates 14 to be deposited on the filter media 43 . Due to the geometry of the openings 54 , the particulates 14 that are trapped by the filter media 43 tend to build up a more even dust cake along the entire length of the filter media 43 . This even dust cake promotes a better filtering efficiency and allows for more thorough cleaning with lower bag wear. In addition, the resulting dust cake produces a lower pressure drop between the filtering assembly 26 and the cleaning assembly 30 because there is no restriction (venturi) at the top of the bag opening. The lower pressure drop and higher filter efficiency allow the dust collector 10 to function at high efficiency and volume with significantly less filter media 43 . [0025] When a significant amount of particulate 14 covers the filter surface 32 , the filter media 43 should be cleaned. During the cleaning operation (as is best seen in FIG. 2 ), the cleaning assembly 30 uses bursts of high velocity air to clean the filter media 43 thus increasing efficiency and prolonging the life of the filter media 43 . In the illustrated embodiment, the pressurized air is provided to each blowpipe 74 and directed to each nozzle 110 on the blowpipe 74 . Each nozzle 110 directs bursts of high velocity air into the mouth of the filter media 43 through the opening 54 . The high velocity air is slowed before entering the opening 54 by a pluming effect, such that the air reaches the mouth of the filter media 43 at ideal cleaning velocities. In one embodiment, the ideal cleaning velocity is between about one-hundred-fifty and two-hundred-fifty feet per second at the opening 54 . In other embodiments, different velocities may be ideal as is known by those skilled in the art. [0026] The illustrated dust collector 10 does not need to stop operation to perform a cleaning operation. The low pressure drop created between the filtering assembly 26 and the cleaning assembly 30 is easily overcome by the stream of cleaning air 114 even while the filtering assembly 26 is running. The cleaning operation forces high pressure air through the primary distribution member 70 where the high pressure air is distributed to the blowpipes 74 , and forced thorough the nozzles 110 and directed into streams of cleaning air 114 that are directed into the mouth of the filter media 43 through the openings 54 . The streams of cleaning air 114 are shot into the filter media 43 in bursts so as to rapidly inflate the filter media 43 and produce a shock or upset that causes the particulates 14 that are trapped on the filter media 43 to dislodge and fall to the filter assembly floor 50 and then down to the particulate removal assembly 22 . [0027] The nozzles 110 are high velocity supersonic nozzles designed to provide a greater volume of induced cleaning air and a more even bag inflation. The greater volume of induced cleaning air produces a larger stream of cleaning air 114 and increases cleaning potential. The even bag inflation allows the filter media 43 to be cleaned more thoroughly, with less shock to the filter media 43 . This results in lower wear and longer life for the filter media 43 . [0028] FIGS. 3 and 4 illustrate a much larger dust collector 200 having two-hundred-fifty-six filter bags 202 . The duct collector 200 includes an upper bin 204 defining a clean air chamber, a lower bin 206 defining a dirty air chamber, and a hopper 208 for directing particulate removed from the bags 202 . A rotary air lock 210 ( FIG. 3 only) is mounted to the bottom of the hopper 208 for the discharge of collected particulate. [0029] The duct collector 200 further includes a manifold 212 for providing compressed air to a series of diaphragm valves 214 . Each diaphragm valve 214 is controlled to selectively provide compressed air to a series of blow pipes 216 . [0030] Referring to specifically to FIG. 4 , each blow pipe 216 extends substantially the full width of the upper bin 204 and includes sixteen cleaning nozzles 218 , 220 . Each cleaning nozzle 218 , 220 is aligned with the opening 222 of a corresponding filter bag 202 . Due to the phenomenon described above in the Summary of the Invention, the pressure of the air provided to the nozzles 218 , 220 on a particular blow pipe 216 is not consistent along the length of the blow pipe 216 . That is, the pressure experienced by the nozzles on the end of the blow pipe 216 nearest the manifold 212 (“nearest nozzles 218 ”) is typically lower than the pressure experienced by the nozzles farthest from the manifold 212 (“farthest nozzles 220 ”). In order to account for this difference in pressure, the configuration of the nearest nozzles 218 is different than the configuration of the farthest nozzles 220 . [0031] In the illustrated embodiment, the goal was to modify the configuration of the nearest nozzles 218 so that they achieve a flow rate (i.e., weight flow rate of air) that is closer to that of the flow rate of the farthest nozzles 220 , even though the pressure of the air provided to the nearest nozzles 218 is less than the pressure of the air provided to the farthest nozzles 220 . In order to achieve this, three nozzle characteristics were modified: throat size A, exit angle α, and exit size B. In the illustrated embodiment, two different nozzle configurations were used, one for the eight nearest nozzles 218 , and the other for the eight farthest nozzles 220 . It should be understood that a larger number of different nozzle configurations could be used. For example, 16 different nozzle configurations could be used along the length of the blow pipe 216 to achieve a more uniform flow rate through the different nozzles. [0032] Referring to FIG. 5 , in the illustrated embodiment, each filter bag 202 is cylindrical in shape and the opening 222 of each bag 202 has a diameter C of about 4.7906 inches. The center of each blow pipe 216 is positioned a distance D of about 18.0 inches from the open end of the corresponding filter bag 202 . Each nozzle includes a converging section 230 , a throat 232 , and a diverging section 234 . The throat 230 is positioned a distance E of about 16.9638 inches from the open end of the corresponding filter bag 202 . [0033] The throat size A is defined as the size of the narrowest portion of the nozzle between the converging section 230 and the diverging section 234 . The exit angle α is defined as an angle at which the air exits the nozzle, and is commonly referenced as a half angle. The exit size B is the size of the nozzle at the nozzle exit. The nozzles also include an inlet length F, an outlet length G, and an overall length H. In the illustrated embodiment, because a cross-section of the nozzles at any location along the length of the nozzle produces a circular interior configuration, the throat size A and exit size B are commonly given as a diameter. [0034] Referring to FIG. 6 , in the illustrated embodiment, the eight nearest nozzles 218 have a throat size/diameter A of about 0.324 inches, an exit angle α of about 7.5 degrees, an exit size/diameter B of about 0.382 inches, an inlet length F of about 0.180 inches, an outlet length G of about 0.220 inches, and an overall length H of about 0.400 inches. The eight farthest nozzles 220 have a throat size/diameter A of about 0.3125 inches, an exit angle α of about 7.5191 degrees, an exit size/diameter B of about 0.3750 inches, an inlet length F of about 0.180 inches, an outlet length G of about 0.237 inches, and an overall length H of about 0.417 inches. It should be understood that the present invention is not limited to the specific dimensions listed above. In fact, depending on the parameters that one is trying to achieve, the dimensions listed above could be quite different and/or other dimensions could be modified to achieve the desired goal. [0035] Thus, the invention provides, among other things, a unique combination of nozzles on a blowpipe that achieves a more equalized flaw rate between the nozzles. Various features and advantages of the invention are set forth in the following claims.	A particulate filtration device comprising filter media having upstream and downstream surfaces, a gas-moving device for moving gas through the filter media from the upstream surface toward the downstream surface, and a cleaning assembly including a blow pipe having a plurality of cleaning nozzles for directing a flow of cleaning gas toward the filter media. A first one of the cleaning nozzles comprises a structural characteristic (e.g., throat size, exit angle, exit size) that is different than a second one of the cleaning nozzles. In one embodiment, the filter media comprises a filter bag corresponding with each nozzle, and both the first one and the second one of the cleaning nozzles are spaced substantially the same distance from the corresponding filter bag. The cleaning assembly can also include a plurality of blow pipes (e.g., each having a plurality of cleaning nozzles) coupled to a gas-pressurized manifold, and a valve positioned between the manifold and each blow pipe to control gas flowing from the manifold to the blow pipes. In this configuration, it is preferred that the nozzle nearer the manifold has a larger throat size, smaller exit angle, and larger exit size than the nozzle farther from the manifold.	1
This application is a continuation of application Ser. No. 07/970,645, filed Nov. 2, 1992, now abandoned, which is a continuation of Ser. No. 07/281,706, filed Nov. 29, 1988, now abandoned. TECHNICAL FIELD The invention relates to the identification in follicular fluid of proteins with FSH-suppressing activity. These proteins can be distinguished from another class of molecules with FSH-suppressing activity, the inhibins, by their lack of reactivity in a specific radioimmunoassay, by their different molecular weight, NH 2 terminal amino acid sequence and absence of subunit structure. BACKGROUND ART The pituitary glycoprotein hormones, follitropin (FSH) and lutropin (LH), are known to be secreted in response to the hypothalamic releasing hormone GnRH. They act on the gonads which in turn product hormones that act as feedback inhibitors. The feedback inhibition of LH is almost entirely due to the action of gonadal steroids, whereas that of FSH is though to be due in part to the action of the gonadal glycoprotein hormone, inhibin, and in part to gonadal steroids. Inhibin has recently been purified to homogeneity and its primary structure determined from gene sequencing. It is a member of a gene family which includes Mullerian inhibiting substance (MIS) and transforming growth factor-β (TGF-β). Inhibin is a heterodimer composed of an A or α subunit and a B or β subunit and in certain species, there are two types of β subunit designated β A and β B giving rise to αβ A and αβ B forms of inhibin. Surprisingly, β A homodimers and β A β B heterodimers were found to exist in follicular fluid and to have an effect opposite to that of inhibin. That is, they act to stimulate FSH synthesis and release and have been termed "activin" [Ling et al (1986) Nature 321 779-782] or "FRP" (FSH-releasing peptide) [Vale et al (1986) Nature 321 776-779]. An overview of the field is given by Tsonis and Sharpe (1986) Nature 321, 724-725. The current invention provides the isolation of a second proteinaceous molecule with FSH-suppressing activity termed FSH-suppressing protein (FSP). Since FSP can suppress FSH levels, FSP will be useful as a contraceptive agent in both sexes; in promoting fertility either by immunisation or by using the rebound effect in FSH levels following FSP administration; or as a diagnostic aid in monitoring gonadal function. However, it is to be noted that whilst this protein has been purified on the basis of its suppression of pituitary FSH production and named FSP, it does not exclude the fact that it may also have major activities (including those of growth factor/differentiation factor) other than that implied by its name. For example, MIS also acts as an oocyte meiosis inhibitor and TGF-β has an FRP/activin-like activity. DESCRIPTION OF THE INVENTION In a first embodiment the invention provides the isolation and characterisation of a unique series of proteins from follicular fluid having FSH suppressing activity termed FSP. They range from 30-60 kD as estimated from SDS-PAGE in the absence of reducing agents. On isolation from bovine follicular fluid they have been further characterized as having identical NH 2 -terminal amino acid sequences. They are distinct from inhibin based on NH 2 -terminal amino acid sequence, molecular mass, absence of subunit structure, absence of inhibin immunoactivity and the failure of neutralizing inhibin anti-sera to neutralize their bioactivity in vitro. Their "inhibin-like" biological activities based on their ability to suppress FSH cell content of pituitary cells in culture are 5-10% that of bovine 31 kD inhibin, upon purification by the method herein described. In one preferred form, the invention provides single chain proteins isolated from bovine follicular fluid (bFF) which have the capacity to suppress FSH secretion in vitro. The single chain proteins have apparent molecular weights of about 31 kD, about 35 kD and about39 kD as determined by SDS-PAGE in the absence of reducing agents. In a second preferred form, the invention provides single chain (glyco) proteins isolated from human follicular fluid (hFF) which have the capacity to suppress FSH secretion in vitro having molecular weights of between about 40 kD and about 60 kD and preferably of about 46 kD or about 55 kD as determined by SDS-PAGE in the absence of reducing agents. It is recognized that it is possible to provide cleavage products, and synthetic equivalents thereof, of proteins of the invention which will maintain the biological or immunological activity of FSP. These cleavage products and synthetic equivalents will also be useful as contraceptive agents or as diagnostic aids in monitoring function. It is also recognized that characterization of FSP including determination of its NH 2 -terminal amino acid sequence provides the possibility of producing FSP by means other than purification from natural sources, as herein described. Such means include utilization of recombinant DNA techniques including cDNA techniques and/or other purification schemes. The invention also provides a composition comprising at least one protein of the invention and a non-toxic carrier or diluent. Compositions of the invention include those suitable for oral administration or in injectable form and preferably include a medically or veterinarily acceptable adjuvant. Also included in the compositions of the present invention are those in sustained release form, particularly suited for implantation and sustained release in a vertebrate. In such a form the composition can be implanted into a vertebrate to affect gonadal function and removed when the desired effect is obtained. The invention also includes a method of affecting gonadal function in a vertebrate comprising administering to said vertebrate an effective amount of a composition of the present invention. In a further form the invention embraces antibody preparations prepared as a result of immunological challenge to a vertebrate by administration of one or more proteins of the present invention or compositions of the present invention. Such antibody preparations include polyclonal and monoclonal antibody preparations. Such antibody preparations can be made as a result of administering proteins or compositions of the invention to a mammalian host by an appropriate route of immunication after emulsification with an appropriate diluent or adjuvant such as Freund's-type adjuvants or Marcol type adjuvants, and utilizing standard vaccination regimes. The antibodies so raised may be polyclonal or monoclonal in nature, this of course being dependent on the method of preparation used. Such antibodies may be used as diagnostic tools or used for passive administration to a host. Throughout this specification and claims use of the term "FSP" is non-species specific and accordingly embraces related species of FSP such as bovine, human, ovine, porcine, equine, chicken and fish and particularly human and bovine FSP. Also the term embraces non-glycosylated and glycosylated FSP species. The term "vertebrate" embraces species of fish, amphibians, reptiles, birds and mammals including humans. The uses described in International patent application No. PCT/AU85/00119 for inhibin will also apply for FSP to the extent that inhibin and FSP have been shown to share biological activity. The invention includes uses of FSP including: a method for suppressing FSH levels in a mammal; a method of raising FSH levels in a mammal; a method of increasing the ovulation rate of a female mammal; a method of increasing spermatogenesis in a male mammal; a method of reducing fertility in a male or female mammal; a method of advancing the onset of puberty in sexually immature male or female mammal; a method of delaying the onset of puberty or suppressing puberty in a male or female mammal; a method for treatment of precocious puberty; a method for the determination of the fertility status of a mammal; and a method for suppressing ovulation in a mammal, each of these methods comprising administration of a protein, composition, or antibody of the invention to the mammal as appropriate and at appropriate dosage. For instance suppression of ovulation will require administration of sufficiently high doses of FSP to suppress LH secretion. The invention also encompasses methods for assaying FSP characterized by use of antibodies of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Notwithstanding the above forms which fall within the broad form of the present invention, preferred forms of the invention will be further described with reference to the following experimental methodology and accompanying drawings wherein: FIG. 1 depicts an RP-HPLC chromatogram showing RP-HPLC of bFF FSP containing fractions following gel permeation fractionation. FSP-containing fractions obtained from two successive gel permeation steps under neutral and acidic conditions were fractionated on an Ultrapore RPSC column using a 30 min linear gradient of 0-50% acetonitrile in 0.1% TFA. In the second panel, dashed lines refer to inhibin immunological activity determined with #749 anti-serum and the solid line with #474 anti-serum. (See text for details). FIG. 2 depicts silver-stained analytical SDS-PAGs of purified preparations of 31, 35 and 39 kD FSP and bovine 31 kD inhibin. Samples were electrophoresed on 12.5% polyacrylamide gels and silver stained. Samples were reduced with β-mercaptoethanol. Molecular wt standards (S) bovine serum albumin 67000, ovalbumin 43000, carbonic anhydrase 29000, goose eggs lysozyme 20800, chick egg lysozyme 14300. I=bovine 31 kD inhibin. FIG. 3 illustrates the effect of FSP and inhibin on basal FSH and LH (media) release and cell content of cultured rat pituitary cells in vitro. The FSH media dose response lines for FSP and inhibin were non parallel. The corresponding dose response lines with FSH cell content were parallel. FIG. 4 illustrates RP-HPLC separation of hFSP bioactivity from hFF. See FIG. 1 for further details. FIG. 5 preparative PAGE of human FSP. FSP-containing fractions obtained after RP-HPLC (See FIG. 4) were further fractionated on 10% PAGs followed by an electroelution step. FSH suppressing activity was determined in each fraction. In relation to protein standard markers (See FIG. 2). FSH suppressing activity was identified in the 40-60 kD region of the gel with peak activities found at 46 and 55 kD. BEST MODES OF CARRYING OUT THE INVENTION The following abbreviations are used in the text. bFF : bovine follicular fluid bFSP : bovine FSH suppressing protein CG : chorionic gonadotropin D : Dalton DTT : dithiothreitol EDTA : ethylenediaminetetraacetic acid ELISA : enzyme-linked immunosorbent assay FRP : FSH releasing peptide FSH : Follitropin or follicle stimulating hormone FSP : FSH suppressing protein x G : times the force due to gravity g : gram GnRH : Gonadotropin releasing hormone or LHRH hFF : Human follicular fluid hFSP : Human FSH suppressing protein HPLC : high performance liquid chromatography k : (prefix) kilo l : litre LH : Lutropin or luteinising hormone LHRH : luteinising hormone releasing hormone M : molar concentration m : (prefix) milli MIS : Mullerian inhibiting substance mol : mole MW : molecular weight p : (prefix) pico n : (prefix) nano PAG : polyacrylamide gel PAGE : polyacrylamide gel electrophoresis PCMB : parachloromercuribenzoic acid PMS : post-menopausal serum PMSF : phenylmetnylsulfonylfluoride PMSG : pregnant mares serum gonadotropin RIA : radioimmunoassay RP-HPLC : reversed phase HPLC SDS : sodium dodecylsulfate SS : steer serum Tris : tris(hydroxymethyl)aminomethane μ: (prefix)micro wt : weight EXAMPLE 1 THE ISOLATION AND CHARACTERISATION OF A PROTEIN FROM BOVINE FOLLICULAR FLUID (bFF) CALLED FSH SUPPRESSING PROTEIN(FSP) General Methods The protein separation methods employed were based on those previously described for the isolation of bovine 31 kD inhibin ]Robertson et al. (1986) Mol. Cell Endocrinol. 44 271-277]. Bovine follicular fluid was fractionated by gel permeation chromatography on Sephacryl S200HR (Pharmacia) in 0.05M ammonium acetate pH 7.0. Following a pH precipitation step, the void volume fractions were fractionated by gel permeation on Sephadex G100 (Pharmacia) in 4M acetic acid. The 31 kD inhibin-containing fractions were then separated by reversed phase HPLC (FIG. 1). FSH-suppressing activity located in fractions 52-60 eluted earlier than 31 kD inhibin (fractions 61-68). The FSP-containing fractions were rerun using a shallow 20-40% acetonitrile gradient in 0.1% TFA under similar reversed phase HPLC conditions based on change in gradient steepness factor. Samples were then fractionated on a 10% acrylamide SDS-PAGE system [Laemmli U.K. Nature (1970) 227 680-685] and the samples recovered from the gel by an electroelution step [Hunkapiller et al. Methods Enzymol. (1983) 91 227-236]. To remove SDS from the electroeluted samples, they (containing ca. 3% SDS) were diluted to a final concentration of 0.2% SDS with 0.1% TFA and applied to a Brownlee RP300 column (30×2.1 mm, Applied Biosystems Inc.) and fractionated on a 30 min 0-70% acetonitrile gradient in 0.1% TFA at 0.4 ml/min. Eluted samples were collected in siliconised tubes in the presence of 20 μl 0.02% SDS and lyophilized. The amino acid sequence determination was performed using a gas/liquid phase model 470A sequencer (Applied Biosystems Inc.) and PTH-amino acids identified by HPLC [Zimmerman et al., Anal Biochem. (1977) 77 pp 569-573]. The protein sequence data base from Protein Identification Resource, NBRF, Georgetown University Medical Center was employed for assessment of sequence identities. Pituitary cell cultures from adult male Spraque-Dawley rats were prepared as previously described [Scott et al., Endocrinology (1980) 107 pp 1536-1542]. Inhibin and FSP fractions were added on day two of culture and the media and cells separated on day five. FSH and LH were determined in media and cell lysates by RIA. Inhibin activity was determined by an in vitro bioassay method [Scott et al., (1980)] utilizing the above culture conditions with a bFF preparation as standard previously calibrated in terms of an ovine testicular lymph preparation. The in vitro neutralization procedure [McLachlan et al., Mol. Cell Endocrinol. (1986) 46 pp 175-185] consisted of the incubation of a volume of an inhibin anti-serum with graded doses of inhibin or FSH-suppressing activity for 2 hours at 20° C. The samples were then added to the pituitary cell culture wells and the degree of neutralization calculated by comparing the dose-response lines in the presence or absence of various anti-sera concentrations. Inhibin immunoactivity was determined using a second antibody radio immunassay [McLachlan et al., (1986)] employing idoinated 31 kD inhibin as tracer and either an anti-serum (#474) raised against bovine 58 kD inhibin [McLachlan et al., (1986)] or an anti-serum (#749) raised against bovine 31 kD inhibin [McLachlan et al., J. Clin. Endocr. Metab. (1987)]. These methods showed minimal or non-detectable cross-reaction against bovine inhibin α and β subunits and a large range of growth factors [McLachlan et al., (1987)]. The standard employed was a partially purified 31 kD bovine inhibin preparation. Isolation and Characterization bFF was fractionated by sequential gel permeation chromatography under neutral and acidic pH conditions followed by reversed-phase HPLC and preparative SDS-PAGE. FSH-suppressing activity associated with non-detectable inhibin immunological activity was identified in fractions eluting earlier than inhibin on reversed phase HPLC (FIG. 1). The combined FSP-containing fractions were separated by preparative SDS-PAGE and the activity electroeluted from the gel. Bioactivity was identified in varying proportions according to the batch, in the 31, 35 and 39 kD regions of the gel. Three bioactive polypeptides were isolated with molecular masses of 31, 35 and 39 kD as determined on SDS-PAGE (FIG. 2). Under reducing conditions, molecular masses of 45 kD, 42 and 39 kD, and 41 and 38 kD respectively, for the 31, 35 and 39 kD forms of FSP were obtained indicating that these polypeptides were probably a single chain structure with microheterogeneity arising from COOH-terminal truncation and/or glycosylation. All three polypeptides had identical NH 2 -terminal amino acid sequences (Table 1) as deduced from automated Edman degradation. TABLE 1__________________________________________________________________________Residues identified (Cycle Number)FSP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18__________________________________________________________________________31kD G N S/C T L R Q A K N G -- -- Q V L Y K35kD G N S/C T/W* L R Q A K N G R -- Q V L Y K39kD (G) N S/C -- L (R) Q A K N G (R) S/C Q V L Y K__________________________________________________________________________ *The assignment of threonine was ambiguous because the signal was lower than expected for the amount of protein sequenced. Initial yields were 24, 160 and 20 pmol respectively. Bracketed amino acids were identified with less certainty. The major signal detected at cycle 3, 13 was in the position of the dithiothreitol adducts of PTH-serine and PTH-cystine. This signal, in the absence of an authentic PTH-serine signal suggested either a modified serine or a cysteine residue. The only contaminating sequences detected gave signals of 5 pmol or less in the case of the 35 and 31 kD analyses. The inhibin-like biological activity of FSP was examined in a rat pituitary cell culture assay (FIG. 3). FSP suppressed basal FSH release (50% inhibitory concentration IC 50 =0.18 nM) and FSH cell content (IC 50 =0.22 nM) in a similar manner to inhibin although the FSH release dose-response lines were non-parallel. No dose related effects of FSP and inhibin was observed on basal LH release and LH cell content. Using the FSH cell content as a basis for a bioassay, FSP exhibited the following inhibin biological activities: 31 kD FSP, 89 U/μg protein; 35 kD FSP, 72 U/μg protein and 39 kD FSP, 35 U/μg protein. These specific activities are 5-10% that of bovine 31 kD inhibin (750 U/μg). Accordingly, the protein has an inhibin-like bioactivity based on the ability to suppress FSH cell content of pituitary cells taking into account confidence limits within the methodology of Scott et al. (1980) between 27 U/μg and 114 U/μg. The range of bioactivities for the entire range of 30 kD to 60 kD proteins is between 27 U/μg and 300 U/μg. The reactivity of bFSP in a previously described inhibin RIA system [McLachlan et al (1986) Mol. Cell. Endocr. 47, 175] was negligible. Consequently, the calculated biological:immunological ratio of bFSP is >320 whilst it is 0.35 for 31 kD bovine inhibin as determined using an anti-inhibin antiserum. FSP inhibin like bioactivity was not significantly neutralized by an inhibin anti-serum in the in vitro neutralization assay in contrast to the neutralization of a maximally suppressed dose of 31 kD inhibin bioactivity. The observation that some 39 kD FSP preparations contained a 35 kD protein suggest that 35 kD and perhaps 31 kD FSP are processed forms of 39 kD FSP. FSP is not inhibin, nor contaminated inhibin, based on its different sequence, its molecular weight, absence of subunit structure, non-detectable inhibin immunological activity and the failure of inhibin anti-serum to neutralize FSP biological activity in vitro. [Robertson et al., (1986)]. The available amino acid sequence data for FSP shows no homology to inhibin but partial (40%) identity to a number of diverse proteins including phosphoenolpyruvate carboxylase, bovine intestinal calcium binding protein and human interferon α-1 precursor, of which only the latter protein demonstrated growth regulating activity. Although inhibin itself has not been shown to exhibit growth regulatory activity, other proteins structurally similar to inhibin [e.g. activin (inhibin β subunit dimer [McLachlan et al., Bailliere's Clin. Endocrinol. and Metab. (1987) 1 pp 89-112]), TGF-β [Roberts et al., Cancer Surveys (1985) 4 pp 683-705], Mullerian Inhibitory Substance [Cate et al., Cell (1986) 45 pp 685-698]] do so. Further, due to the homology between FSP and human α interferon, it is interesting to note that it has been suggested that human α interferon interacts in vivo with the function of both FSH and LH. In a study involving normally cycling healthy women [Kauppila K. et al., Int. J. Cancer (1982) 29, 291-294] circulating concentrations of FSH and LH were not affected by interferon administration in contrast to serum sex steroids indicating that diminished serum steroid concentrations were not due to a decreased release and/or synthesis of FSH and LH. The results of the study suggest that interferon modulates the function of both FSH and LH by partially blocking their stimulatory action on ovarian steroidogenesis. Human leukocyte-derived interferon has also been shown to exert an inhibitory effect on Leydig cell steroidogenesis in vitro [Grava et al (1985) Biochem. Biophys. Res. Commun. 127 809-815]. The inhibin-like in vitro biological activity of FSP showed a number of similarities with inhibin. For example, the FSH, but not LH, basal release and cell content were inhibited indicating the FSP can exhibit at least two actions, namely the ability to inhibit FSH release and to promote FSH degradation, activities which previously have been demonstrated with inhibin [Farnwork P. G. et al., Endocrinology (1987) in Press]. Using FSH cell content as an in vitro bioassay end point FSP is 5-10% as active as inhibin. Nonetheless it is still highly potent in vitro (IC 50 =0.2 nM) suggesting that it may play an alternative physiological role in suppressing FSH. EXAMPLE 2 a. Human FSP (hFSP) The presence of FSP in hFF was investigated using a similar approach to that used for the characterisation of FSP from bFF. In vitro bioactivity was located in fractions earlier eluting than inhibin in the reversed phase HPLC step used in fractionation of inhibin from hFF (FIG. 4). No detectable immunological activity was found associated with this region of FSH suppressing activity using inhibin radioimmunoassays which were used in identifying human inhibin in its purification from hFF. Fractionation of the bioactive fractions on preparative-PAGE resulted in the recovery of bioactivity in the 40-60 kD region of the gel with peaks of activity at 46 and 55 kD (FIG. 5). The molecular weight range of hFSP (40-60 kD) was in the upper range of that observed with bFSP (30-52 kD) but lower MW forms may also exist in low abundance and not be detected here. Alternatively, differences in glycosylation may account for some alterations in MW. INDUSTRIAL APPLICATION Uses of FSP In International patent application No. PCT/AU85/00119 uses of inhibin were described. As discussed in this application FSP demonstrates similar biological activity to inhibin. It should be readily recognised that uses described in that application for inhibin will also apply to FSP. FSP or parts thereof in accordance with the invention provide antigens which may be used as immunogens to immunise man or animals against endogenous FSP. One possible application is to elevate FSH titres and/or increase fertility. FSP or derivatives thereof may be used as bioactive or therapeutic agents in man and in animals. One possible application is to depress circulating FSH titres and thus act as a contraceptive. Removal of FSP following administration may result in a rebound in FSH titres and thus increase fertility. FSP may be used in the treatment and diagnosis of cancers and may have applications as a growth factor or cell differentiation factor. FSP or derivatives thereof may also be used in the diagnosis and treatment of fertility disorders.	Polypeptides exhibiting an inhibitory action over follitropin are disclosed. These polypeptides are designated follitropin suppressing proteins, or "FSP's," and range in size from 30 to 60 kD as determined by SDS-PAGE. Uses for FSP's, including regulation of fertility and as immunogens, are disclosed.	0
PRIORITY DOCUMENT The present invention is a continuation of U.S. patent application Ser. No. 11/235,742, filed Sep. 27, 2005, the content of which is incorporation herein by reference in its entirety. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to spoken dialog systems and more specifically to a system and method of disambiguating multiple intents in a user utterance. 2. Introduction Conversational natural language interactive voice response (IVR) systems encourage callers to speak naturally and express their intent to a speech application without any constraints on how they can speak or what they can say. For example, the IVR systems indicate to the user that it is their turn to speak by saying “How may I help you?” This is an open-ended question in which the user can then simply ask a question. Within that question the user may indicate multiple questions, such as desiring both a cost and an availability of a product. One problem that arises from caller's speech when it contains multiple intents. The problem relates to how the IVR system decides what intent to process first or which intent the caller actually wants processed. An additional problem relates to the current approach in resolving such ambiguity. If the IVR system is looking for specific intents of the user, such as defining one “intent” as the desire to know the price of something, the IVR system may categorize an input as having a confidence score associated with that intent. An example of this may be that the system assigns a 0.6 confidence score to an utterance that it believes is a price request. The current approach uses just the confidence score whereby the intent classified by the spoken language understanding (SLU) model with a higher confidence is selected for processing. However, empirical evidence shows that using confidence scores often leads to an incorrect choice because of other factors affecting the data that is used to train the language understanding module. For example, the unequal distribution of utterances representing the various caller intents can sway the confidence associated with each intent. When the natural language IVR makes an incorrect choice, three negative consequences arise: (a) a caller may be sent to the wrong termination point leading to caller frustration; (b) when such termination is a separate IVR there is loss of revenue because not only will the caller not complete their call, but the network minutes used increases affecting the average handle time for the call; and (c) callers sent to the incorrect termination point are likely to drop out and call back leading to increased costs. What is needed in the art is an improved manner of managing the spoken dialog where a user includes multiple intents in a user utterance. SUMMARY OF THE INVENTION Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth herein. The present invention addresses the deficiencies in the prior art by providing an improved dialog for disambiguating a user utterance containing more than one intent. The invention comprises methods, computer-readable media, and systems for engaging in a dialog. The method embodiment of the invention relates to a method of disambiguating a user utterance containing at least two user intents. The method comprises establishing a confidence threshold for spoken language understanding to encourage that multiple intents are returned, determining whether a received utterance comprises a first intent and a second intent and, if the received utterance contains the first intent and the second intent, disambiguating the first intent and the second intent by presenting a disambiguation sub-dialog wherein the user is offered a choice of which intent to process first, wherein the user is first presented with the intent of the first or second intents having the lowest confidence score. BRIEF DESCRIPTION OF THE DRAWINGS In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: FIG. 1 illustrates an exemplary spoken dialog system; FIG. 2 illustrates an example computing device for use with the invention; FIG. 3 illustrates a method embodiment of the invention; FIG. 4A illustrates a call flow associated with an aspect of the invention; and FIG. 4B illustrates a continuation of the call flow of FIG. 4A . DETAILED DESCRIPTION OF THE INVENTION Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the invention. Spoken dialog systems aim to identify intents of humans, expressed in natural language, and take actions accordingly, to satisfy their requests. FIG. 1 is a functional block diagram of an exemplary natural language spoken dialog system 100 . Natural language spoken dialog system 100 may include an automatic speech recognition (ASR) module 102 , a spoken language understanding (SLU) module 104 , a dialog management (DM) module 106 , a spoken language generation (SLG) module 108 , and a text-to-speech (TTS) module 110 . The present invention focuses on innovations related to the dialog management module 106 and may also relate to other components of the dialog system. ASR module 102 may analyze speech input and may provide a transcription of the speech input as output SLU module 104 may receive the transcribed input and may use a natural language understanding model to analyze the group of words that are included in the transcribed input to derive a meaning from the input. The role of DM module 106 is to interact in a natural way and help the user to achieve the task that the system is designed to support. DM module 106 may receive the meaning of the speech input from SLU module 104 and may determine an action, such as, for example, providing a response, based on the input. SLG module 108 may generate a transcription of one or more words in response to the action provided by DM 106 . TTS module 110 may receive the transcription as input and may provide generated audible speech as output based on the transcribed speech. Thus, the modules of system 100 may recognize speech input, such as speech utterances, may transcribe the speech input, may identify (or understand) the meaning of the transcribed speech, may determine an appropriate response to the speech input, may generate text of the appropriate response and from that text, may generate audible “speech” from system 100 , which the user then hears. In this manner, the user can carry on a natural language dialog with system 100 . Those of ordinary skill in the art will understand the programming languages and means for generating and training ASR module 102 or any of the other modules in the spoken dialog system. Further, the modules of system 100 may operate independent of a full dialog system. For example, a computing device such as a smartphone (or any processing device having a phone capability) may have an ASR module wherein a user may say “call mom” and the smartphone may act on the instruction without a “spoken dialog.” FIG. 2 illustrates an exemplary processing system 200 in which one or more of the modules of system 100 may be implemented. Thus, system 100 may include at least one processing system, such as, for example, exemplary processing system 200 . System 200 may include a bus 210 , a processor 220 , a memory 230 , a read only memory (ROM) 240 , a storage device 250 , an input device 260 , an output device 270 , and a communication interface 280 . Bus 210 may permit communication among the components of system 200 . Where the inventions disclosed herein relate to the TTS voice, the output device may include a speaker that generates the audible sound representing the computer-synthesized speech. Processor 220 may include at least one conventional processor or microprocessor that interprets and executes instructions. Memory 230 may be a random access memory (RAM) or another type of dynamic storage device that stores information and instructions for execution by processor 220 . Memory 230 may also store temporary variables or other intermediate information used during execution of instructions by processor 220 . ROM 240 may include a conventional ROM device or another type of static storage device that stores static information and instructions for processor 220 . Storage device 250 may include any type of media, such as, for example, magnetic or optical recording media and its corresponding drive. Input device 260 may include one or more conventional mechanisms that permit a user to input information to system 200 , such as a keyboard, a mouse, a pen, motion input, a voice recognition device, etc. Output device 270 may include one or more conventional mechanisms that output information to the user, including a display, a printer, one or more speakers, or a medium, such as a memory, or a magnetic or optical disk and a corresponding disk drive. Communication interface 280 may include any transceiver-like mechanism that enables system 200 to communicate via a network. For example, communication interface 280 may include a modem, or an Ethernet interface for communicating via a local area network (LAN). Alternatively, communication interface 280 may include other mechanisms for communicating with other devices and/or systems via wired, wireless or optical connections. In some implementations of natural spoken dialog system 100 , communication interface 280 may not be included in processing system 200 when natural spoken dialog system 100 is implemented completely within a single processing system 200 . System 200 may perform such functions in response to processor 220 executing sequences of instructions contained in a computer-readable medium, such as, for example, memory 230 , a magnetic disk, or an optical disk. Such instructions may be read into memory 230 from another computer-readable medium, such as storage device 250 , or from a separate device via communication interface 280 . FIG. 3 illustrates a method embodiment of the invention. Using dialog design to disambiguate multiple intents in a natural language application comprises in one aspect three steps. First step is to set the confidence threshold for the spoken language understanding to ensure or encourage that multiple intents are returned ( 302 ). As an example of this, a threshold of 0.1 may be set in order to include both intents with lots of utterances as well as those with not so many. This is important since, almost always, those intents with lots of utterances will be returned by the SLU. The threshold may insure that two intents are provided in return or may encourage or prompts the return of multiple intents. For example, a 0.3 threshold may encourage multiple intents but not as many as a 0.1 threshold. The next step is to determine whether an utterance contains single or multiple intents ( 304 ). This can be accomplished at the DM module. Finally, all utterances with multiple intents are sent to a disambiguation sub-dialog where they are offered the choice to select (decide) the intent they want processed ( 306 ). These options improve the dialog in a number of ways, for example, by giving the user control, saving system resources, and increasing call completion rate. The disambiguation sub-dialog will present to the user the first option of the multiple user intents with the lowest confidence score and end the sub-dialog prompt with the intent having the highest confidence score. FIGS. 4A and 4B illustrate a flow chart of example steps according to an aspect of the invention. In natural language conversational IVR, as a call is initiated ( 400 ) and after introductory notices such as the call may be recorded ( 402 ) and a welcome prompt ( 404 ), callers hear an open-ended opening prompt that does not constrain the user response in any way. For example “Welcome to AT&T. I am an automated assistant. How may I help you?” ( 406 ). A user responds with a caller utterance that is applied to a spoken language understanding (SLU) grammar ( 408 ). The process next determines whether multiple intents above a threshold (such as, for example, 0.1) from the list are in the utterance ( 412 ). If yes, the process comprises obtaining disambiguation from the multiple intents ( 414 ). As an example, in response to the initial prompt a caller can say “I would like the price of a refill”. This caller utterance is processed by the SLU and may return two caller intents: (a) caller is asking for price with a confidence score of 0.3; and (b) caller is asking for a refill with a confidence score of 0.8. This difference in confidence scores arises when some intents have more utterances instantiating those categories in the data used to train the SLU, as a result such intents receive higher confidence score than intents with fewer utterances. If the SLU confidence threshold is set low, such as to 0.1, multiple intents may be processed in the disambiguation sub-dialog of the dialog manager (or call flow). In this disambiguation sub-dialog, the IVR plays a prompt of the following nature that is tailored to suit the particular multiple intents under consideration. The system says “I heard more than one request and I would like to clarify exactly what you want to handle first. If you are calling to get the price of your medication, say I need the price of medication” or “If you are calling to order a refill on an existing prescription, say ‘I need a refill’, please say the one you want now”. Given these prompts from the system, the caller decides what they want the IVR to handle thus avoiding all of the problems discussed above. Table 1 illustrates examples of how disambiguation prompts may be concatenated together for multiple automated intents. Using this table requires the concatenation of an initial, middle and closing prompt. Example steps for concatenating the prompts may include step 1: Play the relevant prompt from the queue of 5195 to 5207 that matches the lower score from the two ambiguous call types. Thus, if there are two intents or two call types in the utterance, the system will pick the one with the lower confidence score to “discuss” first. Step 2 involves inserting a conjunctive phrase [5194]; step 3 involves playing the relevant prompt from the queue of 5195 to 5207 that matches the higher score from the two ambiguous call types. Finally, step 4 involves playing a closing prompt 5208. TABLE 1 Call Type Tag Tag Name Spoken Text For any utterance with 2 automated intents 5197 Call type Or conjunction Refill 5195 Middle prompt If you are calling to order a refill on an existing prescription that you receive through the mail from ACME Health Solutions, say, “I need a refill” When Refill 5196 Middle prompt If you are calling to know when you can order your next refill, say, “next refill date” Refills 5197 Middle prompt If you are calling to know how many refills you have left, say, Remaining “How many refills left” Vacation Fill 5198 Middle prompt If you are calling to refill your medication before going away on vacation, say, “vacation advance” Order status 5199 Middle prompt If you are calling to find out the current status of an ongoing order you've sent in, say, “I need an order status” Pharmacy Loc 5200 Middle prompt If you are calling to locate retail participating pharmacies in your area, say, “I need to locate a retail pharmacy” Explain 5201 Middle prompt If you are calling to find out the instructions for getting Procedure prescriptions by mail, say, “How do I get started?” Pay Bill 5202 Middle prompt If you are calling to make a payment, say, “I need to make a payment” Eligibility 5203 Middle prompt If you are calling to check the eligibility status for an individual, say, “I need to check eligibility” Pricing 5204 Middle prompt If you are calling to get the price of your medication, say, “I need the price of medication” Forms and 5205 Middle prompt If you are calling to order materials such as forms, envelopes, or Brochures brochures, say, “I need forms” Enter/Update 5206 Middle prompt If you are calling to enter information for a credit card on file, CC say, “Update my credit card” SOBA 5207 Middle prompt If you are calling to order a summary of all the prescriptions you have received in the past year from ACME Health Solutions, say, “Account printout” 5208 Closing prompt Please say the one you want. Table 1 also shows the steps to disambiguate user input where there is a request for a customer service representative (CSR) plus one or more automated intents. For example, the person asks to speak to a customer representative but included in the utterance is at least one intent that may be handled automatically. This requires the concatenation of initial, middle and closing parts of the dialog. Using this table 1, an example of how the system would concatenate the prompts where there is a disambiguation need for a CSR request plus at least one automated intent. Example steps may include step 1: play the initial prompt [5209]; step 2: select the relevant phrase from 5210-5219 that matches the highest confidence score for the automated call type(s); step 3: play initial prompt 2 [5220]; step 4: insert the conjunctive phrase [5194]; step 5: play the relevant prompt from the queue of 5221 to 5233 that matches the lowest score from two ambiguous call types (irrelevant if there is only CSR_1 automated intent.). The last few steps may comprise step 6: insert the conjunctive phrase [5194] (irrelevant if there is only CSR+1 automated intent); step 7: play the relevant prompt from the queue of 5221 to 5233 that matches the highest score from two ambiguous call types; and step 8: play the closing prompt [5208]. INSERT TABLE 2 Call type Tag Tag Name Spoken Text CSR Request by Special DNIS CSR + 5209 Initial prompt 1 If you're calling to ask a customer service representative a question about Select relevant one 5210 [refill] 5211 [order status] 5212 [retail pharmacy location] 5213 [home delivery instructions] 5214 [payment] 5215 [eligibility] 5216 [pricing] 5217 [forms and brochures] 5218 [statement of benefits] 5219 [Updating of credit card information] 5220 Initial prompt 2 Say, “I need customer service” 5194 Call type Or conjunction Refill 5221 Middle prompt If you want to quickly use our automated system to process the refill of an existing medication that you receive through the mail from ACME Health Solutions, say, “I need a refill” When Refill 5222 Middle prompt If you want to quickly find out from our automated system when you can order your next refill, say, “Next refill date” Refills 5223 Middle prompt If you want to quickly find out from our automated system how Remaining many refills you have left, say, “How many refills left?” Vacation Fill 5224 Middle prompt If you want to quickly use our automated system to process the refill of your medication before going a3way on vacation, say, “vacation advance” Order status 5225 Middle prompt If you want to directly find out from our automated system the current status of an ongoing order you've sent in, say, “I need an order status” Pharmacy Loc 5226 Middle prompt If you want to quickly use our automated system to locate retail participating pharmacies in your area, say, “I need to locate a retail pharmacy” Explain 5227 Middle prompt If you want to quickly hear from our automated system instructions Procedure for getting prescriptions by mail, say, “How do I get started” Pay Bill 5228 Middle prompt If you want to quickly use our automated system to make a payment, say, “I need to make a payment” Eligibility 5229 Middle prompt If you want to quickly use our automated system to check the eligibility status for an individual, say, “I need to check eligibility” Pricing 5230 Middle prompt If you want to quickly use our automated system to get the price of your medication, say, “I need the price of medication” Forms and 5231 Middle prompt If you want to quickly use our automated system to order materials Brochures such as forms, envelopes, or brochures, say, “I need forms” Enter/Update 5232 Middle prompt If you want to quickly use our automated system to enter CC information for a credit card in file, say, “Update my credit card” SOBA 5233 Middle prompt If you want to directly use our automated system to order a summary of al the prescriptions you have received in the past year from ACME Health Solutions, say, “account printout” 5208 Closing prompt Please say the one you want. Returning to FIG. 4A , if the list does not have multiple intents above the threshold ( 412 ), then the method comprises applying precedent rules, such as, if an utterance contains a specific call type (such as Request (Call_Transfer) and (any other calltype), then return ONLY the other calltype or if an utterance contains a calltype (Yes, Hello) and (any other calltype), then return ONLY the other calltype ( 418 ). The call may be finished at this point if ONLY the other calltype is returned and everything is finished. In one aspect of the invention, the call flow receives the input from ( 420 ) which is the result of the disambiguation of multiple intents ( 414 ). A dialog counter counts the dialog turns ( 420 ) and determines if the dialog counter is above a threshold such as 3 ( 422 ). Any threshold will suffice. If the dialog threshold has been met, then the system will provide input indicating that a customer service representative will be contacted for the question ( 424 ) and the call is transferred ( 428 ). If the dialog counter is not above the threshold ( 422 ), then the call flow proceeds to FIG. 4B . In this figure, the first step is to get information associated with the disambiguation of the multiple intents above the threshold ( 430 ). The system provides a prompt, such as “I heard more than one request and I would like to clarify what you want to handle first” ( 432 ). The system then provides the disambiguation prompt taken from table 1 or table 2. Step 434 in FIG. 4B involves providing the disambiguation prompt according to table 1 or table 2. The user provides another utterance. If the utterance is another type of response, a counter is triggered ( 436 ) and a determination is made about whether the counter is above a threshold ( 438 ). If the threshold is met, the system prompts for a re-iteration of the input ( 440 ) and the process returns to provide the disambiguation prompt again ( 434 ). An option for if the threshold is not met is to send the caller to a customer representative ( 428 ). If the utterance in response to the disambiguation prompt is a valid response (typically identified as only one of the two call types being confirmed), then the system returns to the normal dialog with an answer ( 442 ). If the utterance includes a new request, where, for example, the caller requests a CSR ( 444 ). If the request is a CSR request ( 444 ) then the system sends the caller to the CSR ( 428 ). If the new request is something else, a counter is triggered ( 446 ) and a threshold is determined ( 448 ). If the counter is above a threshold value, then the system presents a prompt telling the caller that they will be transferred to a customer representative ( 456 ) and the call is routed ( 428 ). If the counter indicates that the count is less than a threshold ( 448 ), then a dialog counter threshold is checked ( 450 ) and the caller is either sent to step A ( 452 in FIG. 4B to 410 in FIG. 4A ) to process the user utterance with the SLU grammar or the caller is routed to step L ( 454 in FIG. 4B to 426 in FIG. 4A ) to provide a prompt indicating that the caller will be routed to a customer service representative. There are several unique features associated with this invention. First, it provides intelligent constraints in an unconstrained system by offering the user complete control in making a decision about their intent instead of the machine in a participatory manner. Another benefit is the sequence of how the choices are presented to the caller is guided by established psycho-linguistic principle called the “end-focus principle”. This principle says that a dialog should put the more salient questions or concepts at edges (i.e., beginning or end) where native speakers of the language can “naturally” retrieve them cognitively and auditorily. Based on this principle, an aspect of the invention is to handle the intent with the lower confidence first and the one with the higher confidence last. Assuming that the preponderance of certain intent classes indicates user preference, then playing those higher confidence intents last allows the user to make effective choices. This invention is heavily needed to build trust in natural language conversational systems and succeeds in getting an unconstrained system to function effectively. This innovation is significant because it takes away one of the negatives against natural language IVRs, the allegation that “anything goes” and so it does not work. This innovation provides a participatory user interface for caller and system to collaborate for a successful call completion, with the attendant revenue benefits. Embodiments within the scope of the present invention may also include non-transitory computer-readable storage media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or combination thereof) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of the computer-readable media. Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, objects, components, and data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps. Those of skill in the art will appreciate that other embodiments of the invention may be practiced in network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. Embodiments may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination thereof) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. Although the above description may contain specific details, they should not be construed as limiting the claims in any way. Other configurations of the described embodiments of the invention are part of the scope of this invention. For example, the call flow can certainly vary from that shown in FIGS. 4A and 4B inasmuch as the primary focus of the invention is the disambiguation prompts and not the overall call flow. Accordingly, the appended claims and their legal equivalents should only define the invention, rather than any specific examples given.	The present invention addresses the deficiencies in the prior art by providing an improved dialog for disambiguating a user utterance containing more than one intent. The invention comprises methods, computer-readable media, and systems for engaging in a dialog. The method embodiment of the invention relates to a method of disambiguating a user utterance containing at least two user intents. The method comprises establishing a confidence threshold for spoken language understanding to encourage that multiple intents are returned, determining whether a received utterance comprises a first intent and a second intent and, if the received utterance contains the first intent and the second intent, disambiguating the first intent and the second intent by presenting a disambiguation sub-dialog wherein the user is offered a choice of which intent to process first, wherein the user is first presented with the intent of the first or second intents having the lowest confidence score.	6
BACKGROUND AND GENERAL DESCRIPTION OF THE INVENTION Nomenclature The present invention provides composition of matter for novel mitosene analogues funtionalized at the N-2 nitrogen. The term mitosene is an abbreviation of the chemical name 2,3-dihydro-9-hydroxymethyl-6-methyl-1-H-pyrrolo[1,2a]indole-5,8-dione, carbamate (Webb, et. al. J. Am. Chem. Soc. 84, 3185 (1962)). The common name 2,7-diaminomitosene, for example, has amino groups at the 2 and 7 carbon positions of the mitosene structure as follows: ##STR1## General Description of the Invention Rationale for designing compounds of the present invention is an extension of the finding that the mitomycin C reductive activation product 2,7-diaminomitosene forms noncovalent bonds with deoxyribonucleic acid (DNA) (D. M. Peterson, Diss-Abstr-Int-B. 48, 2331 (1987)). The ideas of the actual conception were to create 2,7-diaminomitosene analogues which have the general structure: ##STR2## and are: A) are prodrugs that release the cytotoxic 2,7-diaminomitosene, and/or B) target release of the prodrug by glutathione cleavage of a disulfide bond or aminosulfenyl bond, or C) target release of the prodrug through hydrolysis of an amide, ester or thiolester, or D) take advantage of selective uptake of the mitosene analogue or prodrug through a polyamine, peptide, oligosaccharide or nucleotide transport system, or E) have a functional group that enhances the binding of the agent to DNA such as an oligonuclotide, polypeptide, oligosaccharide or polyamine, or F) have a functional group such as ethanethiol which could produce an additional toxic species (ethylene sulfide) upon prodrug activation by glutathione. Since mechanisms of action are difficult to prove, utility of these compounds is based on their own empirical antitumor, antimicrobial and/or antiviral activity and not on whether or not the agents act by these particular mechanisms. Advantages of the Present Invention One advantage of these mitosenes versus mitomycin analogues is reduced general toxicity. Agents currently used to treat cancer like mitomycin C can be limited by their serious toxic side effects. Compounds which deliver 2,7-diaminomitosene without producing the quinone methide (see scheme below)--a potent alkylating species which results from reductive activation of mitomycin C--are expected to be less toxic. Attack by the quinone methide on various biological macromolecules within a cell (e.g. Nu1=an enzyme) can be toxic. Delivering 2,7-diaminomitosene without the requirement of going through the quinone methide intermediate should reduce prodrug toxicity. ##STR3## Another potential advantage of the new mitosenes is reduced cell resistance. Current cancer drugs like mitomycin C can be limited by resistance. Drug resistance can occur when high levels of reduced glutathione are present. A proposed mechanism for resistance is nucleophilic trapping of the quinone methide agent (Nu1=glutathione) before 2,7-diaminomitosene and/or crosslinks can form. Properly selecting analogues that would release 2,7-diaminomitosene in the presence of high glutathione levels would avoid the mechanism for mitomycin resistance and actually take advantage of this property of resistant cells for targeted delivery of the agent. ##STR4## Shown above is the potential to form two toxins which could be employed to adjust toxicity. Comparison of Present Invention to Mitomvcin Analogues ##STR5## A clear distinction of the present invention from mitomycin analogues is the presence of a double bond in the 9-9a position for the mitosene. Mitomycin analogues do not possess this double bond and are commonly known in the literature as mitosanes. An even more important distinction is a methylene group at C-1 of the 2,7-diaminomitosene analogues in contrast to an aziridine ring in the mitomycin analogues. Since the mitosene has a methylene, it does not have a suitable leaving group to generate the quinone methide. This inability to form the quinone methide is what gives the mitosene analogues their advantages of reduced toxicity and reduced resistance. Certain compounds of the present invention contain the general moiety R═CH 2 CH 2 SSR' (ethyldisulfide groups) which the prior art teaches to attach to an oxygen or nitrogen in the C7 position of the mitosane structure (e.g. U.S. Pat. Nos. 4,866,180 and 5,103,018). In the present invention, the ethyldisulfide groups are attached to the N2 position instead of the N7 position and the resulting composition of matter is a mitosene structure instead of a mitosane structure. The mitosene structure will not form DNA crosslinks and hence is proposed to work by a unique mechanism from the mitosane which is not dependent on the R group. Comparison of Present Invention to Mitosenes in Prior Art Since 2,7-diaminomitosene, N-2 R═H, is disclosed in the open literature, it is not a patentable entity (M. Tomasz & R. Lipman, Biochemistry 20, 5056 (1981)). It (2,7-diaminomitosene) has also been shown to possess antimicrobial activity albeit less toxic than mitomycin C under the conditions it was tested (B. Iynegar, R. Dorr, N. Shipp & W. Remers, J. Med. Chem. 33, 253 (1990)). This result, however, could have been influenced by the positively charged amine on 2,7-diaminomitosene which would retard its bioavailability via decreased solubility across a hydrophobic membrane. Attachment of appropriate R groups described in the summary of the invention could increase hydrophobicity by masking the positively charged N-2 amine or facilitate uptake through a cellular transport system and hence increase bioavailability. Other known 2,7-diaminomitosene derivatives of the general structure are the N-2 R═COCH 3 (D. M. Peterson and J. Fisher, Biochemistry 25, 4077 (1986); M. Tomasz & R. Lipman, Biochemistry 20, 5056 (1981)) and N-2 R═CH 3 , SO 2 CH 3 or SO 2 C 6 H 4 pCH 3 (I. Han, D. J. Russell & H. Kohn, J. Org. Chem. 57, 1799 (1992)). These compounds (R═COCH 3 , CH 3 , SO 2 CH 3 , and SO 2 C 6 H 4 pCH 3 ) were produced for chemical studies and are not implicated in their ability to act as antitumor agents. Since these structures are known, however, they are specifically excluded from the mitosene analogue descriptions below. The general structure is also distinguished from the mitosene analogues which do not possess an amino group at N-2, and/or have an oxygen attached to the analogous C-1 position (M. Maliepaard, et. al., Anti-Cancer Drug Design, 7, 415-425 (1992) and U.S. Pat. No. 3,429,894 "Acetylated Mitosenes"). Moreover, these structures do not have the essential embodiment of a methylene group at C-1 which prevents the formation of a quinone methide. ##STR6## DETAILED DESCRIPTION OF THE INVENTION Appropriate Choice of R Group The present invention relates to N-2 functionalized analogues of 2,7-diaminomitosene of the general structure above wherein R is not H, COCH 3 , CH 3 , SO 2 CH 3 , or SO 2 C 6 H 4 pCH 3 but is appropriately chosen from: A straight or branched alkylene group and/or aromatic group of 1-30 carbons. A straight or branched alkylene group of 1-30 carbons, which contains 1-20 heteroatoms (e.g. O, N, P or S). A polyamine with 2-10 amines containing at least 2 carbon atoms but less than 30. Substitutions of amines can be done with other heteroatoms (e.g. O or S). Compounds of specific mention are those structures which have putrescine, spermine or spermidine attached directly to the mitosene (i.e. 2putrescine, 7-aminomitosene; 2-spermidine,7aminomitosene 2-spermidine,7-aminomitosene). Linkers containing 1-30 carbon atoms and 0-10 heteroatoms can also be used to attach the polyamine to N-2 (e.g. 2-aminocarbonyl-spermine, 7-aminomitosene). An amino acid, or peptide with 2-30 aminoacids, attached directly through an amide bond to N-2 (e.g. 2aminoarginine, 7-aminomitosene, or 2-aminolysine, 7aminomitosene). An amino acid, or peptide with 2-30 aminoacids, attached to N-2 through a linker which contains 0-30 carbons and 1-10 heteroatoms (e.g. N, O, or S). In these compounds the amino acid/peptide is attached to the linker by an aminoacid's carbonyl, amino or functional group (e.g. 2-amino-ethanethiol-arginine, 7-aminomitosene which attaches the ethanethiol linker to the carbonyl group of the amino acid via a thioester bond). A nucleoside, nucleotide or oligonucleotide with 2-30 nucleotides. This group can be attached to N-2 through a phosphoamide bond, through a C--N bond with C5' of a nucleotide ribose (or deoxyribose), a sulfenylbond with a C5' thioribose (or deoxyribose), or through a linker described for the aminoacid analogues. An oligosaccharide consisting of 1-30 sugar moieties attached through the anomeric carbon to N2 of the mitosene or through a linker (described above for the peptides) to any of the heteroatoms on the oligosaccharide, or An analogue which is functionalized with a known amino acid protecting group (e.g. o-nitrophenylsulfenyl chloride or 2-nitrobenzyl chloroformate). A metabolite or catabolite from the fatty acid, citric acid cycle, urea or nucleotide pathways. In the case of compounds containing several functional groups like citrulline, the compound could be be attached via a carbamate, amide, linker or other suitable means of bonding to an amine. A heteroatom containing branched or straight chained alkylene group of 0-10 carbons. In the case of zero carbons, the heteroatom, such as sulfur, is attached directly to the N-2 amino group. These compounds can be esterified with a carbonyl compound, be attached to an organic compound through a disulfide bond or attached directly to an alkyl, alkylene, or aromatic group. Specific examples of mention are 2-aminosulfenylphenyl-(ortho or para) NO 2 , 7aminomitosene and 2-aminoethyldisulfidebenzene(ortho or para)NO 2 , 7-aminomitosene and 2-aminoethylthiobenzoyl, 7-aminomitosene). Replacement of the the nitrophenyl group can be done with an alkyl group or other organic functional group. Glutathione would be one possible functional group. A compound where N2 forms an azo, aziridino or hydrazine bond with an organic amine. A compound where N2 is replaced with another heteroatom. Enablement, Best Mode and Forseeable Variations Forseeable variations at C-7, C-6 and/or C-10 which are known for mitosane analogues are also expected to be possible for the 2,7-diaminomitosene analogues. Some specific examples of compounds within the described invention are shown below with their common mitosene names for clarification. This list is not intended to be comprehensive but comprises the envisioned best mode of practice. Chemistry for modifying primary amines is well known in the art. The present invention relates to attaching functional groups to the primary amine at N2 on 2,7-diaminomitosene using appropriately modified procedures. It is forseeable that improvements to these current techniques will continue to be made, making it possible to produce the mitosene compounds in greater yield although high yield is not considered to be a necessary embodiment for this composition of matter invention. There are two important considerations which must be taken into account when modifying the literature procedures of primary amines to 2,7-diaminomitosene which may be necessary to improve yields. First, the possibility of modifying N7 exists in addition to the desired N2 modification. The N2 position is the most reactive due to the electron withdrawing effects of the quinone ring on the N7 amine and it should be possible to create conditions which enhance the selectivity (e.g. solvent, order and rate of addition, temperature, stoichiometry of the reagents, etc.) without undue experimentation. For example, formation of amides on 2,7-diaminomitosene with acetic anhydride results in substantially quantitative modification at N2 (D. M. Peterson & J. Fisher, Biochemistry 25, 4077 (1986)). Should the N7 position also react, however, the multifunctionalized compound would be a forseeable modification also having the desired utility within the scope of the invention. Second, mild conditions are desired when adapting literature procedures of amine reactions due to the lability of certain portions of the mitosene compound--especially the carbamate. If the carbamate is removed in the modification of N2, it is reasonable to assume that standard procedures for adding a carbamate group could be employed to help increase yield. The decarbamoyl mitosene, however, is also considered to be covered under the scope of the present invention since the carbamate is a desired but not necessary feature of the compounds. Should the C10 oxygen of the decarbamoyl mitosene also react with the functionalizing agent used to react with N2, the resulting compound with R attached at C-10 decarbamoyl O and N2 would be a forseeable variation which would retain utility. As an intermediate starting material, 2,7-diaminomitosene can be prepared from a variety of literature procedures where mitomycin C is reduced under slightly acidic conditions (e.g. M. Tomasz & R. Lipman, Biochemistry, 20, 5056 (1981)). It is forseeable that one well trained in the art could produce the 2,7-diaminomitosene using organic synthesis by appropriately adapting the references contained in Maliepaard et. al. and other mitosene synthetic procedures and thus avoid the need for mitomycin C as a starting material. The R-stereochemistry at C-2 is potentially achievable using serine as a reactant starting material. Mitosene carbons C1 through C3 are added to an indole after OH-->Cl and CO 2 H-->CHO conversions on serine. The CHO group is attached to indole nitrogen via schiff base formation and NaBH 3 CN reduction. The alternative S-stereochemistry is a forseeable variation which would also have activity. EXAMPLE ##STR7## For the title compound, o-nitrophenysulfenylchloride (oNPSCl) is added using the General procedures for protection of amino acids (e.g. Zervas et. al., J. Am. Chem. Soc. 85, 3660 (1963)). Generally, approximately one equivalent of o-nitrophenylsulfenylchloride is dissolved in THF and added to a mitosene solution in THF and 2N NaOH. The compound of interest is extracted with CH 2 Cl 2 and is purified on silica Gel using 5:1 CH 2 Cl 2 :EtOAc. High purity is verified by reverse phase C-18 HPLC using an isocratic eluting system of 60:40 MeOH:0.01M KH 2 PO 4 , pH 6.5 buffer. NMR (d 6 -DMSO, 300 MHz) δ8.27 (d, 1H, J=8 Hz, NPS-H), 7.8 (pseudo dd, 2H, J=8,8 Hz, NPS-H), 7.39 (pseudo t, 1H, J=7, 8 Hz, NPS-H), 6.52 (broad s, 4, C7-NH 2 , C10-OCONH 2 ), 5.51 (s, 1H, N2-H), 4.98 (dd, 2H, J=12, 17 Hz, C10-H 2 ), 4.16-4.23 (m, 3H, C2-H & C3-H 2 ), 3.03 (dd, 1H, C1-H, J=6, 17 Hz), 2.86 (apparent d, 1H, C1-H, J=16 Hz), 1.71 (s, 3H, C6-CH 3 ). EXAMPLE ##STR8## The title compound can be synthesized with standard carbamate producing reagents. A common reaction to form carbamates is reaction of an amine with sodium cyanate (NaOCN) in an acetic acid:water solution. EXAMPLE ##STR9## 2,7-diaminomitosene can potentially be modified with an in situ mixture of oNPSCl and ethylene sulfide. Typically, the oNPSCl and ethylene sulfide are mixed just prior to addition to 2,7-diaminomitosene. While there is not an appropriate indication of this chemistry in the literature, the possible mechanism of this reaction is shown below which seems reasonable to assume will work when the appropriate conditions to reduce ethylene sulfide polymerization are worked out. ##STR10## If this reaction turns out to require undo experimentation, there are many other reactions which are possible to make the title compound and are too numerous to efficiently list here. EXAMPLE ##STR11## Amides such as this compound can be obtained by reacting a pyridine solution of 2,7-diaminomitosene with the appropriate anhydride or acid chloride. EXAMPLE ##STR12## The 2,7-diaminomitosene starting material can be modified by 2-nitrobenzyl chloroformate, a known amino acid protecting group. Since UV light can be used to remove this protecting group, targeted release of 2,7-diaminomitosene could be achieved using a light energy source (e.g. lamp or lazer) directed at the area of existing or excised tumor tissue. EXAMPLE Peptide/Amino acid analogues ##STR13## The N2 amine position is modified using standard peptide synthesis methodologies which are well known in the art. A mild protecting group strategy is preferable as the 2,7aminomitosene moiety can be sensitive to strong acids, bases and reducing agents. The oNPSCl and DTS protecting groups are suggested because they can be removed with sulfhydryl reagents. The protected amino acids (e.g. oNPS-arginine, oNPS-lysine or any amino acid with a suitable protecting group) are coupled to 2,7-diaminomitosene using dicyclohexylcarbodiimide (DCC). N-hydroxylsuccinimide is routinely used to help the condensation reaction. The oNPS protecting group is removed with a sulfhydryl reagent such as β-mercaptoethanol. EXAMPLE polyamine adducts ##STR14## A polyamine such as spermine can be coupled to 2,7-diaminomitosene using carbodiimidazole via a carbonyl linker or by direct displacement of a triazine formed with one of the spermine nitrogens by the N-2 mitosene nitrogen. To increase yields, a suitable protecting group, such as trifluoroacetic anhydride (or chloride), can be used to block one of spermine's primary nitrogens prior to the reaction. Removal of the trifluoracetic acid protecting group can be done with methanolic ammonia. EXAMPLE nucleotide adducts ##STR15## Standard oligonucleotide synthesis methodologies which are well known in the art can be used to react the 2-amino group or 2 aminoethanethiol group with an activated phosphate group. Mild protection strategies should be employed to avoid degradation of the mitosene moiety during deprotection. ##STR16## Compounds such as these can be obtained by dissulfide exchange resulting in displacement of a labile thiol such as o-NPS from 2-aminoethyldissulfide-o-nitrobenzene by 5' thiol or 5' thiophosphate nucleotides, respectively. EXAMPLE Diazo and hydrazine bond linkages ##STR17## Diazo derivatives of 2,7-diaminomitosene can be made by reaction with the appropriate nitroso compound formed by reacting a primary amine with K 2 S 2 O 8 (potassium persulfate). Hydrazine species can be formed by mild reduction of the diazo compounds although a significant degradation of the 2,7-diaminomitosene compound could occur. Other suitable methods of preparing hydrazines are well known in the art. EXAMPLE R groups with more than one way of attachment to an amine ##STR18## Multifunctional R groups such as citrulline can be attached in a variety of ways. In general, the following funtional groups can be attached to the N2 primary amine. The suggested generalized procedures can be replaced with other reactions well known in the art. ______________________________________FunctionalGroup Attachment______________________________________Carboxylic Amide bondacid Use anhydride or acyl chloride in pyridine or condesation with appropriate agent such as DCC.Amine Carbonyl or other suitable linker Use carbodiimidazole or other reagent for desired linker. Diazo or hydrazine Preform nitroso amine with K.sub.2 S.sub.2 O.sub.8 and react with N2. Reduce diazo to form hydrazine. Replace an amine in structure with N2 (i.e. minus one nitrogen-- amine of structure is attached directly to the mitosene backbone). Form triazine from amine and displace with N2.Thiol Sulfenyl bond Use appropriate sulfenyl chloride Dissulfide bond with thiol linker Dissulfide exchange of a mitosene dissulfide such as 2-aminoethyldisulfide-o-nitrobenzene.Carbamate Replace a carmamate amine with N2 as decribed for amine (terminal NH.sub.2 of carbamate is attached directly to the mitosene backbone) React N2 with appropriate cyanate reagent.Sulfate Sulfonamide bond React N2 with appropriate sulfonyl chloride.Phosphate Phosphoamide bond React N2 with appropriate activated phophate. Choose an appropriate linkerAlcohol Choose an appropriate linker (e.g. a dicarboxylic acid forming an amide bond to the mitosene and ester bond to the alcohol). One option: React alcohol with cyclic anhydride and condense with N2 using DCC.______________________________________	The present invention relates to analogues of 2,7-diaminomitosene, a mitomycin C metabolite, useful as antitumor, antimicrobial and/or antiviral agents. These analogues involve functionalization of the N-2 nitrogen with organic groups.	2
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the priority of U.S. Provisional Application No. 60/643,701 entitled “Rocket Propelled Grenade, Variant II” filed Jan. 13, 2005, the contents of which are incorporated herein by reference in their entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0002] This invention was made with Government support under Contract N61339-00-D-0001 with the Department of the Navy. The Government has certain rights in this invention. FIELD OF THE INVENTION [0003] Embodiments of the invention generally relate to devices, systems, and methods for simulating the operation and effect of various weapons, especially explosive weapons, during military training exercises. More particularly, the invention relates to devices, systems and methods for simulating the operation and effect of weapons such as rocket propelled grenades (RPG's) in a laser-based battle simulation environment BACKGROUND OF THE INVENTION [0004] At present, in live battlefield military operations in areas such as the Middle East, opposing forces using weapons such as the rocket-propelled-grenade (RPG) are presenting a significant threat to U.S. military forces stationed there. In an RPG weapon, a relatively small rocket charge is mounted in a tube, together with a grenade, which can then be aimed and launched at a target. One example of a commercially available RPG device is the RPG-7, which has been manufactured in a number of countries, including Russia and various Eastern European countries such as Romania, over its forty-plus year history. FIG. 1 is an illustration showing a prior art Russian-made RPG-7 antitank grenade launcher 2 (“RPG 2 ”). The RPG 2 is a recoilless, shoulder-fired, muzzle-loaded, reloadable weapon, capable of firing an 85-mm (PG-7) or 70-mm (PG-7M) rocket-assisted High Explosive Anti Tank (HEAT) grenade from a 40-mm smoothbore launcher tube. Features of the RPG 2 include a flared blast shield 3 (which also serves as the breech through which the charge can be loaded). The charge is provided to initially launch the grenade assembly from the firing tube. 3 , a telescope optical sight 4 , an iron sight 5 , a heat shield 6 (which in this illustration is made of an insulating material such as wood), a trigger 7 , a grenade 8 , such as the PG-7VM grenade, and include a pair of hand grips 9 A, 9 B. The RPG 2 is light enough (around 15 pounds) to be carried and fired by one person. [0005] With the RPG 2 , launch of the grenade 8 is typically via a gunpowder booster charge (not visible in FIG. 1 ) at about 115 m/s, and this launch creates a cloud of light bluish grey smoke (which typically puffs out in the vicinity of the blast shield 3 . It is the sight of this smoke that is often the only warning (i.e., a visual indicator) that a potential target has alerting the target that the RPG 2 has been fired. After the grenade 8 such as the 70 mm PG-7M is fired from the RPG 2 , the PG-7M's internal rocket motor will ignite after the grenade 8 has traveled about 10-11 meters, giving the grenade 8 higher velocity, a relatively flat trajectory, and better accuracy. In addition, when the grenade round exits the tube of the RPG 2 , several sets of fins 8 A at the rear of the grenade round 8 unfold, to maintain direction and induce rotation. The maximum effective range of the RPG 2 is about 500 meters for stationary targets and 300 meters for moving targets, with a maximum overall range of about 920-1100 meters, at which point the grenade 8 will self destruct (typically about 4-5 seconds after it was launched). The fuse sets the maximum range of the grenade 8 . One way the timed detonation of the RPG 2 has been used is to create rough proximity airbursts against targets such as helicopters once the targets have passed the preferred 100 meter “head-on attack” zone. In addition, some grenades used with the RPG 2 can penetrate armor up to 330 millimeters. [0006] Although the RPG 2 generally won't travel as far as a larger rocket, the RPG 2 is far more portable (it can be held over a shoulder), lightweight, simple to use (literally “point and shoot”) and, unlike indirect weapons such as mortar, can be more directly aimed at a target, to produce damage essentially equivalent to a stick of dynamite detonated at the target location. Further, because the blast radius of anti-armor round fired by an RPG 2 is around 4 to 8 meters, personnel and/or equipment in proximity to an RPG blast will still experience significant negative effects from it. For example, personnel may experience effects such as temporary deafness and blindness from an RPG blast even if such persons are not permanently harmed or killed by the blast. [0007] Because the RPG 2 is so simple to use, effective, damaging, and widely available, it has become the weapon of choice for many forces around the world, including many guerilla armies and insurgents hostile to U.S. interests. Consequently, the U.S. military has great interest in training its personnel to deal with military combat situations in which RPGs may be used. [0008] One way that the U.S. military trains its forces to deal with various military combat situations is using laser-based combat simulation systems. Such laser-based systems have been developed to simulate military combat situations without actually having to fire live ammunition. These systems use relatively low power lasers and matched detectors for indicating when a “hit” has occurred. One such system is the Multiple Integrated Laser Engagement Systems, referred to as the MILES system. Military forces in the U.S. and around the world have found MILES to be an important tool to help soldiers and others learn combat survival skills and evaluate battle outcomes, and MILES training has been proven to dramatically increase the combat readiness and fighting effectiveness of military forces. [0009] An illustrative implementation of MILES uses so-called eye-safe “laser bullets,” combined with the use of laser sensitive detectors, to simulate battlefield situations. Each individual and vehicle in the training exercise has a detection system to sense hits and perform casualty assessment. For example, as part of an exemplary MILES event, some soldiers are equipped with one or more laser detectors (e.g., an optical detector) capable of receiving a coded laser signal or pulse that has been fired, and these laser detectors can be attached to the soldier himself, to a vehicle the solder is riding on or in, or to any other location proximate to a target of interest. Other soldiers are equipped with laser transmitters capable of “shooting” coded laser signals and/or pulses of infrared energy. These laser transmitters can be readily attached to and detached from any location, person, or thing (e.g., vehicle mounted weapons, hand carried weapons, vehicles, tanks, etc.). In some implementations, one or more of the coded laser signals and/or pulses are modulated to indicate the type of weapon that is the source of the laser beam; and a soldier identification number may also be included in the transmitted signal. [0010] When the laser sensitive detectors receive the coded laser signal/pulse(s), one or more MILES decoders determine whether the target was hit and, if so, whether the “laser bullet” was accurate enough to cause damage (e.g., a casualty). This determination can be made in various ways, such as by whether the coded signals/pulses exceed a threshold, whether the coded signals/pulses actually hit its intended target, and the like. In some implementations, the target (and/or the shooter) can be made aware almost instantly of the accuracy of a simulated shot, such as by audible alarms, visible displays, pyrotechnics, and the like, where these indicators can designate a hit or near miss and also help to provide realism for the soldiers. [0011] In more recent implementations of MILES, all action by shooters and targets (deemed “players”) is recorded during a simulated event, so that a so-called After Action Review (AAR) can occur later, to review the effectiveness of the weapons and/or of the defenses against them. For example, one implementation of AAR allows commanders to process, format and view engagement data collected during an exercise, for review after the exercise. In addition, exercise data can be archived for future use, such as to provide additional training for military forces. SUMMARY OF THE INVENTION [0012] The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. [0013] In one embodiment, to help mitigate the threat of devices such as RPGs, the invention provides a surrogate training device simulating an RPG, where the training device is usable with a laser-based system such as the MILES system. The surrogate training device, which simulates the RPG (minus the launch of an actual grenade at a target) provides a simulation of predetermined characteristics of the RPG, such as the aesthetics (e.g., “look and feel”), weight, appearance, and physical features, such as the muzzle flash (e.g., an incandescent flash at a weapon muzzle following departure of the arms being used, which can be caused be the ignition of oxygen, the expulsion of burning powder grains and the expansion of powder gasses), smoke trail and sounds that occur when a grenade is launched from an actual RPG. [0014] In one embodiment, the invention provides a rocket propelled grenade (RPG) simulation device usable with a laser detector, the RPG simulation device comprising a laser transmitter, a switch, a controller, and a housing. The laser transmitter is capable of directing a laser signal to the laser detector, the laser signal comprising information readable by the laser detector, to simulate a launch of a rocket propelled grenade from the RPG simulation device to the laser detector. The switch permits a user to trigger a laser signal from the laser transmitter. The controller is in operable communication with the laser transmitter and the switch, and the controller is operable to respond to triggering of the switch and to simulate the launch of a rocket propelled grenade by directing the laser transmitter to generate and transmit a laser signal. The housing simulates at least one predetermined characteristic of an actual RPG device. The housing is constructed and arranged to house at least one element selected from the group consisting of the laser transmitter, the switch, and the controller. [0015] The laser signal can comprise a pulse of laser energy. The RPG simulation device can further comprise an anti-tank weapons effect systems simulator (ATWESS) in operable communication with the controller, the ATWESS generating an indicator replicating a physical effect that occurs when an RPG launches a grenade. When the switch is triggered, the controller can command the ATWESS to generate the indicator replicating the physical effect. For example, the indicator can comprise at least one physical effect selected from the group consisting of a noise, a visual effect, a gaseous effect, muzzle flash, smoke, an audible effect, and a blast sound. [0016] The RPG simulation device can further comprise a display in communication with the controller, wherein the display is constructed and arranged to display information related to operation of the RPG to an operator of the RPG. For example, the displayed information can comprise at least one piece of information selected from the group consisting of round count, player identification number, laser power level, rounds remaining, weapon type, and battery level. In addition, the RPG simulation device can include indicators capable of indicating to a user that a laser signal has been transmitted and/or capable of enabling alignment of the laser transmitter. [0017] In one embodiment, the laser transmitter can transmit a laser signal encoded with a MILES code, such as a code recognizable by a MILES-type detector. In one embodiment, the controller can perform additional operations, such as one or more of tracking number of rounds fired; tracking a player identification number, tracking a power level of a laser signal emitted by the laser transmitter; tracking a battery level; generating a programmable hit and near miss word, adjusting a power level of the laser signal emitted by the laser transmitter; adjusting an alignment of the laser signal emitted by the laser transmitter; generating a signal to control the laser signal where the laser signal further comprises a MILES code; tracking MILES code related information in a laser signal that comprises a MILES code; receiving an instruction from an external system via a USB port; providing data to an external system via a USB port; providing information to a display; providing reverse voltage protection; responding to a controller key; responding to a push to read switch; responding to a magnetic switch; responding to a trigger switch; and responding to a safety switch. [0018] In another embodiment, the invention provides a method for simulating operation of a rocket propelled grenade (RPG). A physical structure having at least one predetermined characteristic in common with an actual RPG is provided. A laser transmitter is coupled to the physical structure, the laser transmitter operable to direct a laser signal to a laser detector. A user-accessible control is provided on the physical structure. The laser transmitter is coupled to the user-accessible control so as to enable a user to transmit a laser signal towards a target to simulate launching an RPG at that target. In a further aspect, an anti-tank weapons effect system simulator (ATWESS) is provided, where the ATWESS is capable of generating an indicator simulating a physical effect that occurs when an actual RPG launches a grenade. In still a further aspect, the laser signal can be encoded with a MILES code. [0019] In one aspect, a physical effect is generated when the laser signal is transmitted, the physical effect comprising at least one physical effect selected from the group consisting of sound, muzzle flash, smoke, visual effect, audio effect, and gaseous effect. [0020] In another embodiment, the invention provides a system usable with a detector responsive to a laser signal for simulating the operation of a rocket propelled grenade (RPG) device. The system comprises means for enabling a user to trigger a simulated launch of a grenade from the RPG device; means for directing a laser signal to the detector in response to the simulated launch trigger; and means for generating a physical indicator of the launch. In a further embodiment, the system further comprises means for simulating at least one predetermined characteristic associated with the operation of the RPG device, the at least one predetermined characteristic selected from the group consisting of sound, muzzle flash, smoke, weight, color, shape, housing material, length, range, visual effect occurring when weapon is fired, audio effect occurring when weapon is fired, and gaseous effect occurring when the weapon is fired. [0021] Details relating to this and other embodiments of the invention are described more fully herein. BRIEF DESCRIPTION OF THE DRAWINGS [0022] The advantages and aspects of the present invention will be more fully understood in conjunction with the following detailed description and accompanying drawings, wherein: [0023] FIG. 1 is a prior art image of a rocket-propelled grenade (RPG) launcher and its grenade, as viewed from the right side; [0024] FIG. 2 is a perspective view of a rocket propelled grenade (RPG) simulation device, without the sighting attachment, as viewed from the left side, in accordance with one embodiment of the invention; [0025] FIG. 3A is a left side view of the RPG simulation device of FIG. 2 ; [0026] FIG. 3B is a bottom side view of the RPG simulation device of FIG. 2 ; [0027] FIG. 4 is a first exploded perspective view of the RPG simulation device of FIG. 2 , as viewed from the right side; [0028] FIG. 5 is a second exploded perspective view of the RPG simulation device of FIG. 2 , as viewed from the left side and also including the sighting attachment; [0029] FIG. 6A is an enlarged perspective view of the grenade portion of the RPG simulation device of FIG. 2 ; [0030] FIG. 6B is an enlarged exploded view of the grenade portion of the RPG simulation device of FIG. 2 ; [0031] FIG. 7 is partial cross-sectional enlarged view of the grenade portion of the RPG simulation device of FIG. 2 , showing the grenade mounting and circuit card assembly (CCA) housing cover; [0032] FIG. 8 is an enlarged view of the CCC housing assembly of the RPG simulation device of FIG. 2 ; [0033] FIG. 9A is a first enlarged view showing the mounting of the CCA housing to the front tube, for the RPG simulation device of FIG. 2 ; [0034] FIG. 9B is a second enlarged view showing the mounting of the CCA housing to the front tube, for the RPG simulation device of FIG. 2 ; [0035] FIG. 10 is a perspective view showing the front and rear tubes of the RPG simulation device of FIG. 2 ; [0036] FIG. 11A is an enlarged perspective view showing the rear tube and its blast shield mounting holes, for the RPG simulation device of FIG. 2 ; [0037] FIG. 11B is an enlarged perspective view showing the ATWESS assembly and blast shield mounted to the rear tube, for the RPG simulation device of FIG. 2 ; [0038] FIG. 12A is an enlarged perspective view showing the front grip assembly, including finger guard, for the RGP simulation device of FIG. 2 ; [0039] FIG. 12B is an enlarged side view of the front grip assembly of FIG. 11A , without the finger guard; [0040] FIG. 13 is an enlarged perspective view of the rear grip assembly of the RPG simulation device of FIG. 2 ; [0041] FIG. 14A is an enlarged exploded perspective view of the liquid crystal display (LCD) housing assembly for the RPG simulation device of FIG. 2 ; [0042] FIG. 14B is an enlarged cross-sectional view of the controller key receptacle switch for the RPG simulation device of FIG. 2 ; [0043] FIG. 15 is a wiring harness interconnection diagram for the RPG simulation device of FIG. 2 ; [0044] FIG. 16 is a functional block diagram of the CCA inputs and outputs, used with the RPG simulation device of FIG. 2 ; [0045] FIGS. 17A and 17B are front and side views, respectively, of the dual function laser tube used with the RPG simulation device of FIG. 2 ; and [0046] FIGS. 17C and 17D are front and side views, respectively of a the first laser tube used with the dual function laser tube of FIGS. 17A and 17B ; and [0047] FIGS. 17E and 17F are front and side views, respectively, of the second laser tube used with the dual function laser tube of FIGS. 17A and 17B . [0048] In the drawings, like reference numbers indicate like elements. The drawings are not to scale, emphasis instead being on illustrating the principles of the invention. DETAILED DESCRIPTION [0049] Throughout this document, the term “rocket propelled grenade” (RPG) is used to describe a particular type of weapon being simulated. However, those of skill in the art will recognize that at least some embodiments of the invention are equally applicable to weapons such as rifle-propelled grenades, light anti-tank weapons (LAWs), artillery, mortar, grenades, and rockets. For example, the physical appearance of the RPG simulation device can readily be adapted to match the physical appearance of a weapon such as rifle propelled grenade, light anti-tank weapon, etc., and the physical effects (e.g., sights and sounds) that occur when the respective weapon is used can also be incorporated as part of the simulation device. In addition, note that the term “rocket propelled grenade” is a term of art that refers at least to a weapon that launches a grenade using a rocket, and not merely to the grenade itself that is being launched. [0050] FIG. 2 is a perspective view of a rocket propelled grenade (RPG) simulation device 10 as viewed from the left side, in accordance with one embodiment of the invention. FIGS. 3A-5 provide additional views of the RPG simulation device 10 , including a left side view ( FIG. 3A ), a bottom side view ( FIG. 3B ), a first, exploded, right perspective view ( FIG. 4 ), and a second, exploded, left perspective view ( FIG. 5 ), the latter of which also shows an optional field viewing scope 19 . In one embodiment, the field viewing scope 19 is a Model Red Dot 30, from BSA Optics, Inc. of Ft. Lauderdale, Fla. Because the Picatinny mounting rail 70 (described further herein) is used as the mounting bracket for the field viewing scope 19 , a variety of different scopes may be mounted, if desired. [0051] Referring now to FIGS. 2-5 , the RPG simulation device 10 has aesthetics (e.g., the look and feel) designed to closely simulate an actual RPG, such as the RPG 2 of FIG. 1 . The RPG simulation device 10 also includes MILES technology that enables it to produce a MILES signal 11 usable in a MILES environment to enable, for example, instrumented training events for After Action Review (AAR) training at both military home stations and at combat training centers. The RPG simulation device 10 , in one embodiment, weighs approximately fifteen (15) pounds and has a length of about fifty-one (51) inches. The RPG simulation device 10 is constructed to be water-resistant and has an effective range of 300 to 1000 meters. The RPG simulation device 10 is capable of firing signals that include one or more of selectable MILES codes, a word count, and a player identification number or code. In addition, the RPG simulation device 10 provides a programmable rounds count. [0052] The RPG simulation device 10 includes a simulated grenade 12 , a circuit card assembly (CCA) housing assembly 14 (which itself contains the CCA 80 , described further herein), and a trigger switch 34 . The embodiment of the RPG simulation device 10 as shown in FIGS. 2-5 also includes a housing implemented via a CCA housing assembly 14 , a rear tube assembly 20 , a front tube assembly 16 , a front grip assembly 18 , rear grip assembly 30 , an LCD assembly 32 , field viewing scope 19 and sighting attachment mounting rail 70 , safety switch 53 , an anti-tank weapons effect system simulator (ATWESS) assembly 24 , a blast shield 26 , and a shoulder stop bracket 22 . Each of these elements is described further herein. [0053] As those of skill in the art will appreciate, a housing for the RPG simulation device 10 can be implemented in many different ways. For example, it could be made using a single tube, rather than front and back tubes, with multiple tubes, in fewer or more pieces than illustrated, etc. [0054] FIG. 6A is an enlarged perspective view of the simulated grenade 12 of the RPG simulation device 10 of FIG. 2 , and FIG. 6B is an enlarged exploded view of the simulated grenade 12 , showing where the CCA 80 is disposed (the CCA 80 is disposed within the tubular housing shown in the figure). In one embodiment, the simulated grenade 12 is formed from two symmetrical pieces 12 A, 12 B of a substantially rigid and rugged material, such as polypropylene thermal plastic, and has a color (e.g., olive drab) to mimic the color of an actual grenade. As those of skill in the art will appreciate, however, the simulated grenade 12 can be formed of virtually any material (e.g., metals, composite, plastics, etc.), in any color, which is able to be formed into a grenade-like shape (or the shape of any other warhead being simulated) and able to withstand the rigors of the application and environment where the RPG simulation device 10 is being used, such as operation in an environment with temperatures that can range from 35° C. (−31° F.) to 62° C. (144° F.) [0055] The simulated grenade 12 includes one or more ribs 12 C that help to strengthen the structure of the simulated grenade 12 and to also conform around the CCA housing assembly 14 portion of the RPG simulation device of FIG. 6B . In addition, the simulated grenade 12 includes a plurality of fins 12 D to help mimic the appearance of the actual grenade. [0056] FIG. 7 is partial cross-sectional enlarged view of the simulated grenade 12 of the RPG simulation device 10 of FIG. 2 , showing the simulated grenade mounting and circuit card assembly (CCA) housing cover 18 . In this embodiment, the CCA housing cover 18 is mounted to the CCA housing 14 using four hex socket head screws 17 , and the simulated grenade 12 is secured to the CCA housing assembly 14 using eight Philips screws 21 . The method of mounting, as well as the particular configuration and arrangement of mounting screws is merely illustrative and not intended as limiting. Using screws helps to enable the simulated grenade 12 and/or the CCA 80 (contained within the CCA housing 14 ) to be more easily serviceable. [0057] FIG. 8 is an enlarged view of the CCC housing assembly 14 of the RPG simulation device 10 of FIG. 2 , FIG. 9A is a first enlarged view showing the mounting of the CCA housing to the front tube, for the RPG simulation device of FIG. 2 , and FIG. 9B is a second enlarged view showing the mounting of the CCA housing 14 to the front tube 16 , for the RPG simulation device 10 of FIG. 2 . Referring to FIGS. 8-9 , the CCA housing assembly 14 is constructed of a substantially rigid material, such as aluminum 6061-T6 material, and has an appearance and color (e.g., anodized olive drab) to further mimic the appearance of an actual RPG. The CCA housing assembly 14 is shaped so as to house the CCA 80 ( FIG. 16 ) and also a laser tube assembly 120 ( FIG. 17 ), and includes an opening 15 in which the CCA 80 is mounted, as well as a CCA housing cover 18 . The CCA housing assembly 14 is secured to the front tube 16 with six screws 21 . In addition, an alignment screw 23 (which helps serve as an alignment indicator) is used for orientation and helps to ensure that the CCA housing assembly 14 is installed into the front tube 16 in the same orientation both during production and in later follow on field repairs. [0058] FIG. 10 is a perspective view showing the front and rear tubes 16 , 20 , respectively, of the RPG simulation device 10 of FIG. 2 , coupled together. The front tube 16 and rear tube 20 are each made of a substantially rigid material, such as aluminum 6061-T6. The front tube 16 is inserted into the rear tube 20 and secured by six screws. To simulate the appearance of an actual RPG, the front tube 16 is anodized black and the rear tube 20 is anodized brown. The shoulder stop bracket 22 can be provided in various ways. In one embodiment, the shoulder stop bracket 22 is molded out of a substantially rigid material, such as brown polycarbonate plastic or anodized brown metal and secured to the rear tube 20 , such as by screws, welding, soldering, adhesives, or any other attachment method. In another embodiment, the shoulder stop bracket 22 can be formed integrally with the rear tube 20 . [0059] FIG. 11A is an enlarged perspective view showing the rear tube 20 and its blast shield mounting holes 25 , for the RPG simulation device 10 of FIG. 2 , and FIG. 11B is an enlarged perspective view showing the ATWESS assembly 24 and blast shield 26 mounted to the rear tube 20 , for the RPG simulation device of FIG. 2 . The ATWESS assembly 24 uses an ATWESS cartridge (not shown) and is able to provide on or more indicators or physical effects, such as a realistic weapon signature, including muzzle flash, noise, and backblast smoke, appropriate for the simulation of a grenade launched from an RPG. The ATWESS breech lock lever 49 locks the ATWESS cartridge into place. [0060] ATWESS simulation devices are available from various vendors, including Cubic Defense Systems of San Diego, Calif. In one embodiment, the ATWESS assembly 24 and blast shield 26 are substantially the same as those used on the simulated VIPER device used with the MILES system. [0061] The ATWESS assembly 24 includes an ATWESS breech lock lever 49 (to lock the ATWESS cartridge cover) and an ATWESS safety lever 46 that must be pulled to arm the ATWESS. The blast shield 26 is provided to protect the operator and to collimate the blast from the ATWESS assembly 24 to reduce the likelihood injury to nearby personnel. [0062] FIG. 12A is an enlarged perspective view showing the front grip assembly 28 for the RPG simulation device 10 of FIG. 2 , with the finger guard 50 , and FIG. 12B is an enlarged side view of the front grip assembly 28 of FIG. 11A , without the finger guard 50 . The front grip assembly 28 includes several user accessible controls, including a trigger switch 34 , as well as an internal magnetic switch 47 (not visible in the figures). The magnetic switch 47 communicates with the CCA 80 to activate a Helium Neon Laser Tube located within a so-called dual function laser tube 120 ( FIG. 15 ) that also is in communication with the CCA 80 for alignment purposes. Placing a magnet near the bottom of the front grip assembly 28 can trigger the magnetic switch 47 . The front grip assembly 28 can include a removable finger guard 50 and a cover 51 . To help simulate the appearance of an actual RPG, the front grip assembly 28 is anodized black and the cover 51 is anodized brown and mounted to the rest of the front grip assembly 28 via four counter-sunk screws. The front grip assembly 28 couples to the front tube 16 via screws mounted through a plurality of screw holes 53 . [0063] FIG. 13 is an enlarged perspective view of the rear grip assembly 30 of the RPG simulation device of FIG. 2 . The rear grip assembly 30 houses a battery 65 (e.g., a 9 volt battery) (not visible in this Figure) that is held in place via battery door 64 and battery door knob 66 , which advantageously has a low profile. The rear grip assembly 30 includes a user accessible control, such as the safety switch 42 . During operation, in one embodiment, the safety switch 42 must be engaged prior to engaging the trigger switch 34 . The rear grip assembly 30 , like the front grip assembly 28 , is anodized black, with a brown cover 60 , to simulate the appearance of an actual RPG. The cover 60 is mounted to the rear grip assembly 30 using four counter-sunk screws, and the rear grip assembly couples to the front tube 16 via screws mounted through a plurality of screw holes 63 . [0064] Although the functions of the front grip assembly 28 and rear grip assembly 30 could be implemented in a single grip, it is advantageous if they are provided as part two separate grips to ensure that an operator has both hands on the RPG simulation device 10 when using it, to improve safe use of the RPG simulation device 10 . [0065] FIG. 14A is an enlarged exploded perspective view of the liquid crystal display (LCD) housing assembly 32 for the RPG simulation device of FIG. 2 . The LCD housing assembly 32 includes a liquid crystal display (LCD) 78 , an indicator LED 81 (which illuminates when the RPG simulation device 10 is fired), a reset push button switch 82 (used to reset the RPG simulation device 10 , reset round count, etc.), an LCD housing assembly cover 74 , and LCD cover 76 , and a controller key receptacle switch 36 (also referred to herein as a weapon switch), which is usable with a controller key switch, explained further herein. [0066] In at least some embodiments, the LCD housing assembly 32 includes a so-called Picatinny mounting rail 70 (i.e., a bracket used on some firearms to provide a standardized mounting for accessories such as the field viewing scope 19 ; such a bracket can be provided in accordance with MIL-STD-1913, first published by the U.S. Picatinny Arsenal). Picatinny rails are available from numerous suppliers, including Centurion Tactical Systems of Layton Utah. [0067] FIG. 14B is a cross sectional view of the controller key receptacle switch 36 . As FIG. 14B illustrates, the controller key receptacle switch 36 has four positions and is used to set the RPG simulation device 10 in one of several operating modes. In at least one embodiment, a controlling operator has a first key (i.e., a so-called “green” master key) capable of putting the RPG simulation device 10 into either a so-called “Dry Fire” mode (a mode with no ATWESS, e.g., no smoke) or an ATWESS mode (a mode in which an ATWESS cartridge is used as part of the simulation), and the RPG simulation device operator has a second key (i.e., a so-called “yellow” weapon key). [0068] The following modes of operation are provided by way of example and are not limiting. [0069] To put the RPG simulation device 10 in “Dry Fire” mode, assuming a battery 65 is installed into the rear grip 30 , the green master key is then inserted into the controller key receptacle switch 36 and turned to the “set” position 36 A, and then the green master key is then turned to position 3 ( 36 B in FIG. 14B ). The green master key is then removed from controller key receptacle switch 36 , and the RPG simulation device 10 will be in “Dry Fire mode”. The operator of the RPG simulation device 10 can then press the push to read switch 82 to see an indication of the “Rounds Remaining” on the LCD display 78 (e.g., four rounds remaining). To fire the RPG simulation device 10 , an operator inserts his yellow operator key into the controller key receptacle switch 36 , presses the safety switch 42 ( FIG. 13 ), then the trigger switch 34 ( FIG. 12 ), and the LED 81 illuminates when the laser signal 11 is emitted, when the laser transmitter 206 ( FIG. 16 ) is fired by the trigger switch 34 . The laser transmitter 206 sends a laser signal, such as a pulse of laser energy and/or eye-safe, invisible laser (light) beams, toward the target. If the laser beam hits the target, detector assemblies on the target sense the beam and cause an alarm to sound. In addition, if the target is a vehicle, an externally-mounted light on the vehicle will flash. [0070] Optionally, the operator of the RPG simulator device 10 may wear a harness or vest equipped with a laser detector assembly and alarm and which also includes a similar controller key receptacle switch 36 . The laser detector can, for example, be a detector usable with a MILES-type of system. If a MILES-equipped weapon fires a laser signal at the operator of the RPG simulator device 10 , one of two results may occur: if it is a “near miss” the alarm on the harness sounds for one second; if it is a “hit”, the alarm sounds continuously and the operator has been “killed”. The operator's yellow weapon key can be removed from the RPG simulator device 10 and inserted into the controller key receptacle switch 36 (on the harness) to shut off the alarm. In one embodiment, only the green master key can perform a system reset on the RPG simulator device 10 (which provides for a new set of rounds). [0071] To put the RPG simulation device 10 in “ATWESS” mode, assuming a battery 65 is installed in the rear grip 30 , the green master key is then inserted into the controller key receptacle switch 36 and turned to the “set” position 36 A, and then the green master key is then turned to position 4 ( 36 C in FIG. 14B ). The green master key is then removed from controller key receptacle switch 36 , and the RPG simulation device 10 will be in “ATWESS Mode.” The operator of the RPG simulation device 10 can then press the push to read switch 82 to see an indication of the “Rounds Remaining” on the LCD display 78 (e.g., four rounds remaining). [0072] Operation of the RPG simulator device 10 in ATWESS mode is similar to operation in DRY FIRE mode, except that in ATWESS mode, an operator cannot fire the laser transmitter unless an ATWESS cartridge is loaded and the ATWESS safety lever 46 is in the ARMED position. The operator ensures that the backblast area near the blast shield 26 is clear, and centers the target (e.g. via field viewing scope 19 ). The target is tracked, and the operator then fires at the target, pressing and holding the safety switch 42 first and then the pressing the trigger switch 34 . In one embodiment, the operator can fire a round every 10 seconds, for up to four rounds, with each round using its own ATWESS cartridge. After the firing, an operator can check the “Rounds Remaining” by depressing the push to read switch 82 , and a displayed rounds counter will show rounds remaining. When the round is fired, the ATWESS provides an audible sound equivalent to the sound a real round would make, as well as a blast of smoke similar to that produced during the firing of a “real” rocket propelled grenade. [0073] FIG. 15 is a wiring harness interconnection diagram for the RPG simulation device 10 , of FIG. 2 , showing internal interconnections amongst some of the elements shown in FIGS. 2-14 . All of the components shown in FIG. 15 are interconnected to at least the CCA 80 . In at least one embodiment, the CCA 80 acts as a controller for one or more functions of the RPG simulation device 10 . The CCA 80 couples to a laser tube 120 (which contains one or more lasers, such as a 904 nm Infrared wavelength laser tube, to generate, direct, and control the MILES laser signals that are emitted by the RPG simulation device 10 and to also control the laser alignment signal 11 B (which helps serve as an alignment indicator) used to align the MILES laser signals 11 ( FIG. 2 ) emitted by the RPG simulation device 10 . The laser alignment signal 11 B is activated via a magnetic switch (not visible in FIG. 15 ) that is switched when a magnet is placed in proximity to the bottom 28 A of the front grip assembly 28 . [0074] The CCA 80 is further interconnected with (and responsive to) the trigger switch 34 on the front grip assembly 28 , as well as to a safety switch 42 on the rear grip assembly 30 . The trigger switch 34 and safety switch 42 can be used independently of each other or in conjunction with each other, depending on the mode of operation of the RPG simulation device 10 , as described above. In one embodiment, the RPG simulation device 10 will only fire (in either mode) if the safety switch 42 is pressed and held first and then the trigger switch 34 is pressed. The mode of operation of the RPG simulation device 10 is set via the weapon switch 36 , which, in one embodiment, can be controlled or set via a removable weapon switch key 36 A (e.g., the controller green key described previously). The CCA 80 communicates with and controls the ATWESS assembly 24 , in response to inputs at the trigger switch 34 and safety switch 42 . [0075] The CCA 80 monitors the terminals 44 of battery 65 , to monitor the battery voltage and provide a “low battery” indicator on LCD display 78 of the LCD assembly 32 . The CCA 80 is responsive to the push to read switch 82 and provides a signal to the LED indicator 81 . [0076] FIG. 16 is functional block diagram of the CCA 80 and its inputs and outputs, as used with the RPG simulation device 10 of FIG. 2 . In one embodiment, the CCA 80 is sized to fit in the opening 15 on the CCA housing assembly 14 and is about 3.5 inches by 1 inch in size. The inputs to the CCA 80 include the settings of/signals from the safety switch 42 and main trigger switch 34 , signals monitoring the power/voltage level of the battery 65 , the setting of the controller key receptacle switch 36 , the setting of the push to read switch 82 , the setting of the magnetic switch 47 , the setting of the ATWESS safety arming switch 46 , and inputs from a USB programming interface 55 (USB port). [0077] The outputs of the CCA 80 include a signal controlling the ATWESS 24 , signals to the display 80 and the LED fire indicator 81 , data to the USB port 55 , and the signals directed to the dual function laser tube 120 to energize a laser diode (not visible in the Figure) in the dual function laser tube 120 , so as to cause the RPG simulation device 10 to emit a laser beam (either the MILES laser 106 or an alignment laser 114 ) towards a given target. [0078] The CCA 80 itself includes functionality providing weapons effect simulation control 200 (to control the ATWESS 24 ), weapon round count 202 (where the round count can relate to a specific weapon type via the weapon type control 204 ), signals to control the laser diode 206 , signals to control the laser power level adjustment 208 (including hit and near miss laser power level adjustment), signals to control alignment 210 , signals to control the display 212 (including display of PID, rounds remaining, weapon type, and battery low indicators), capability to track up to 5280 player identification codes (PID) (e.g., Enhanced MILES PID), encoding all existing MILES codes 216 , providing reverse voltage protection 216 , monitoring battery power 220 , and tracking player identification (PID) (e.g., via a 5280 Enhanced PID). [0079] FIGS. 17A and 17B are front and side views, respectively, of the dual function laser tube 120 used with the RPG simulation device of FIG. 2 . FIGS. 17C and 17D are front and side views, respectively of a first laser tube 100 used with the dual function laser tube of FIGS. 17A and 17B . FIGS. 17E and 17F are front and side views, respectively, of the second laser tube 110 used with the dual function laser tube of FIGS. 17A and 17B . As FIG. 17 illustrates, both the MILES laser tube 110 and the alignment laser tube 110 are disposed within the dual function laser tube 120 . [0080] The first laser tube 100 is the MILES laser tube and includes laser transmitter/laser diode that emits a laser beam when energized (such as when an operator presses the trigger switch 34 to cause the CCA 80 to generate a signal to energize the laser transmitter). In one embodiment, the laser transmitter uses a so-called MOCVD (metal organic chemical vapor deposition) type of laser, which is an infra-red, non-visible laser, available from Laser Diode, Inc., of Edison, N.J. [0081] The second laser tube 110 includes a laser transmitter (not visible in FIG. 18 ) capable of generating a read laser “pointer” type beam for alignment purposes. [0082] FIGS. 19A and 19B are front and side views, respectively, of the dual function laser tube 120 used with the RPG simulation device of FIG. 2 , FIGS. 19C and 19D are front and side views, respectively, showing connection of the first laser tube 100 of FIGS. 17A-17C and the second laser tube 110 of FIGS. 18A-18C to the dual function laser tube 120 of FIGS. 19A and 19B . As FIGS. 19A-19D [0083] In describing the embodiments of the invention illustrated in the figures, specific terminology (e.g., language, phrases, product brands names, etc.) is used for the sake of clarity. These names are provided by way of example only and are not limiting. The invention is not limited to the specific terminology so selected, and each specific term at least includes all grammatical, literal, scientific, technical, and functional equivalents, as well as anything else that operates in a similar manner to accomplish a similar purpose. For example, although particular materials (e.g., aluminum, polycarbonate, etc.) are described as being used in various embodiments to construct aspects of the RPG simulation device, those of skill in the art will recognize that numerous other materials could work equally well. Furthermore, in the illustrations, Figures, and text, specific names may be given to specific features, processes, military programs, etc. Such terminology used herein, however, is for the purpose of description and not limitation. [0084] Although the invention has been described and pictured in a preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form, has been made only by way of example, and that numerous changes in the details of construction and combination and arrangement of parts may be made without departing from the spirit and scope of the invention. [0085] In the Figures of this application, in some instances, a plurality of system elements may be shown as illustrative of a particular system element, and a single system element or may be shown as illustrative of a plurality of a particular system elements. It should be understood that showing a plurality of a particular element is not intended to imply that a system or method implemented in accordance with the invention must comprise more than one of that element, nor is it intended by illustrating a single element that the invention is limited to embodiments having only a single one of that respective elements. In addition, the total number of elements shown for a particular system element is not intended to be limiting; those skilled in the art can recognize that the number of a particular system element can, in some instances, be selected to accommodate the particular user needs. [0086] In addition, those of ordinary skill in the art will appreciate that the embodiments of the invention described herein can be modified to accommodate and/or comply with changes and improvements in the applicable technology and standards referred to herein. Variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. [0087] The particular combinations of elements and features in the above-detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the referenced patents/applications are also expressly contemplated. As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention's scope is defined in the following claims and the equivalents thereto. [0088] Having described and illustrated the principles of the technology with reference to specific implementations, it will be recognized that the technology can be implemented in many other, different, forms, and in many different environments. The technology disclosed herein can be used in combination with other technologies. Having described the preferred embodiments of the invention, it will now become apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may be used. These embodiments should not be limited to the disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims.	A rocket propelled grenade (RPG) simulation device usable with a laser detector is provided. The RPG simulation device comprises a laser transmitter, a switch, a controller, and a housing. The laser transmitter is capable of directing a laser signal to the laser detector, the laser signal comprising information readable by the laser detector, to simulate a launch of a rocket propelled grenade from the RPG simulation device to the laser detector. The switch permits a user to trigger a laser signal from the laser transmitter. The controller is in operable communication with the laser transmitter and the switch, and the controller is operable to respond to triggering of the switch and to simulate the launch of a rocket propelled grenade by directing the laser transmitter to generate and transmit a laser signal. The RPG simulation device can further comprise an anti-tank weapons effect systems simulator (ATWESS) in operable communication with the controller, the ATWESS generating an indicator replicating a physical effect (such as noise, a visual effect, a gaseous effect, muzzle flash, smoke, an audible effect, and/or a blast sound) that occurs when an RPG launches a grenade	5
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming process for a metal layer serving as the base of a bump, which process constitutes a part of a process for manufacturing a flip chip IC, in which a metal bump formed on the surface of a semiconductor base is surface-joined to an electrode formed on the surface of a printed circuit board. 2. Description of the Related Art For further progression of the miniaturization of electronic devices, an improvement in parts mounting density is a key factor. In connection with semiconductor ICs, the development of high-density mounting techniques based on flip chips is being actively carried forward as a replacement for the conventional package mounting. There are several types of flip chip mounting methods, such as an Au stud bump method and a solder ball bump method. In any of these methods, a barrier metal is provided between the electrode pad of the semiconductor IC and the bump material for the purpose of achieving an improvement in closeness of contact, preventing mutual diffusion, etc. In the case of the solder ball bump method, this barrier metal determines the finish configuration of the bump, so that it is also called BLM (ball limiting metal). The most typical structure of the BLM layer in the solder bump method is a three-layered structure consisting of Cr, Cu and Au layers. Of these, the Cr layer, which is the lowest layer, serves as the layer which comes into close contact with the electrode pad; the Cu layer serves as the layer for preventing diffusion of the solder; and the top layer, that is, the Au layer, serves as the layer for preventing oxidation of the Cu. The patterning of the BLM layer might be performed by a wet etching method using a liquid agent. In that case, however, various problems would be involved, including poor operability, environmental problems due to the waste liquid, poor accuracy in machining, etc. In view of this, use of a lift-off process as the patterning method for the BLM layer is being considered, in which process a photoresist layer is formed and then separated. In this case, the formation of the BLM layer is usually conducted by using a sputtering apparatus, which leads to a problem in that the formation of the BLM layer tends to extend to the side wall surfaces of the background resist pattern, with the result that the resist separation liquid does not penetrate when the lift-off is to be effected, thereby making it difficult to remove the unnecessary portion of the BLM layer. In view of this, it is necessary to control the configuration of the edge surface of the opening of the photoresist such that it has an overhang-like configuration for the purpose of attaining an improvement in separability in the lift-off operation. This control of the resist configuration might be realized by a lithography process. However, that would involve an increase in the number of steps to be taken. It would be ideal if the control of the resist pattern configuration could be effected during the plasma irradiation, which is usually performed in the process prior to the formation of the BLM layer by sputtering. Conventionally, a plane parallel plate type plasma processing apparatus as shown in FIG. 3 has been used for the purpose of executing the plasma irradiation prior to the formation of the metal layer. The plasma processing apparatus 1 of FIG. 3 includes a plasma processing chamber 2 in which a vacuum is created; a stage 4 (cathode plate) on which a substrate to be processed 3 is placed; and an anode plate 5 that is opposed to the stage 4, which is connected to a high-frequency power source 6 through the intermediation of a coupling capacitor 7. When performing the patterning of the metal by the lift-off of the photoresist, the background resist pattern is deformed into an overhang-like configuration by thermal transformation and ion irradiation, and a break is formed at an edge of the BLM layer formed thereon (Any portion where the step coverage of the sputtering layer is rather poor is utilized for this purpose). Then, a resist separation liquid is caused to penetrate through this break to remove the unnecessary portion of the BLM layer to thereby complete the patterning. However, to perform the control of the background resist pattern through this plasma irradiation in a stable manner, selection of the thickness of the resist layer is also an important factor to be taken into consideration. When a resist pattern of a conventional thickness of approximately 1 μm is used, the region which undergoes thermal transformation by the plasma irradiation will not remain in the resist surface layer but be allowed to reach the interface between that and the background. As a result, the resist layer is bonded to the background, thereby making it difficult to remove the resist pattern by the lift-off in the post-process. This might be avoided by reducing the plasma irradiation amount. However, a reduction in the plasma irradiation amount would result in an in sufficient deformation in the opening edge of the resist pattern, so that the BLM layer formed will be allowed to reach the side wall of the resist pattern, thereby making it completely impossible for the resist separation liquid to penetrate. Thus, the patterning by lift-off will not be completed (See FIG. 1). Further, in the conventional pre-metal-layer-formation process, no special attention is paid to the increase in the temperature of the wafer during the process, so that the maximum temperature of the wafer surface when the plasma processing is performed under the normal conditions will generally reach 200° C. to 250° C. When such a processing is conducted on a specimen wafer on which pattern formation has been performed, the opening edge of the resist pattern will be deformed so as to protrude obliquely upward (See FIG. 2B). It is to be assumed that this is due to the fact that the original molecular structure of the resist layer surface is destroyed by the excessive heat energy applied rapidly thereto, with the result that it undergoes contraction, this surface stress overcoming the force due to thermal expansion with which the resist end portions would expand laterally. In this case, the overhang of the resist opening is insufficient, so that sputter particles are allowed to reach the pattern side walls to form a BLM layer. Thus, in the post process of lift-off, the penetration of the separation liquid does not proceed, so that the patterning is not completed. Further, the resist portion which has undergone excessive thermal transformation is carbonized and bonded to the background (See FIG. 2D). It is accordingly an object of the present invention to provide a metal layer pattern forming method which makes it possible for the configuration of the resist layer to be easily controlled in the pre-processing step prior to the step of forming a BLM (ball limiting metal) layer serving as the multiple metal layer in the formation of a ball bump in a flip chip IC or the like and which does not affect the lower layer. SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a metal layer pattern forming method including a pre-processing step of the BLM-layer-forming step, in which plasma irradiation, the formation of a metal layer, and a lift-off process are effected on a substrate to be processed consisting of a semiconductor base on which an electrode pad, a surface protecting layer and a photoresist layer are successively stacked, wherein the thickness of the photoresist layer is double the thickness of the metal layer or more. In a second aspect of the present invention, in the pre-processing step of the BLM-layer-forming step, the processing condition is set such that the maximum temperature that the surface of the substrate to be processed attains is 100° C. to 150° C. Further, in the plasma processing, it is desirable to use a plasma processing apparatus having a high-density plasma source capable of obtaining a plasma density of not less than 1×10 14 cm 3 but less than 1×10 cm -3 , such as ICP (Inductively Coupled Plasma), TCP (Transfer Coupled Plasma), ECR (Electron Coupled Resonance) or helicon wave plasma. In the present invention, the photoresist layer is sufficiently thicker than the metal layer, so that there is substantially no formation of the metal layer on the side wall of the photoresist layer. Further, the region affected by the thermal transformation does not reach the interface leading to the lower layer, so that the unnecessary portion of the metal layer can be easily separated in the lift-off process. In the second aspect of the present invention, the surface quality of the photoresist layer can be appropriately improved, so that no excessive thermal transformation takes place. Further, by using a plasma processing apparatus having a high-density plasma source that is capable of obtaining a plasma density of not less than 1×10 11 cm -3 but less than 1×10 14 cm 3 , such as ICP (Inductively Coupled Plasma), TCP (Transfer Coupled Plasma), ECR (Electron Coupled Resonance) or helicon wave plasma, the substrate bias voltage and the plasma power can be independently controlled. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A through 1D are sectional views showing how the state of a substrate to be processed changes as the conventional manufacturing process using a thin-film resist pattern proceeds, of which FIG. 1A shows the state in which a photoresist layer has been formed around the connection hole of a passivation layer facing the electrode pad; FIG. 1B shows the state in which the opening configuration of the photoresist layer has been slightly changed by a pre-film-formation process; FIG. 1C shows the state in which a BLM layer has been formed; and FIG. 1D shows the state in which resist separation does not proceed, with the patterning by lift-off not being completed; FIGS. 2A through 2D are sectional views showing how the state of a substrate to be processed on which the metal layer has been formed under the conventional condition of a high rise in wafer temperature changes as the manufacturing process proceeds, of which FIG. 2A shows the state in which a thick photoresist layer has been formed around the connection hole of a passivation layer facing the electrode pad; FIG. 2B shows the state in which the opening edge configuration of the photoresist layer has been slightly hanged by a pre-film-formation process; FIG. 2C shows the state in which a BLM layer has been formed; and FIG. 2D shows the state in which resist separation does not proceed, with the patterning by lift-off not being completed; FIG. 3 is a schematic sectional view of a plane parallel plate type plasma processing apparatus; FIGS. 4A through 4D are sectional views showing how the state of a substrate to be processed changes as a manufacturing process according to the present invention proceeds, of which FIG. 4A shows the state in which a photoresist layer has been formed around the connection hole of a passivation layer facing the electrode pad; FIG. 4B shows the state in which the opening configuration of the photoresist layer has been slightly changed by a pre-film-formation process; FIG. 4C shows the state in which a BLM layer has been formed; and FIG. 4D shows the state in which resist separation does not proceed, with the patterning of the BLM layer by lift-being off being completed; FIG. 5 is a schematic sectional view of a plasma processing apparatus on which an ICP (inductively coupled plasma) is mounted; and FIG. 6 is a schematic sectional view of a substrate stage that is equipped with a temperature control mechanism. DESCRIPTION OF THE PREFERRED EMBODIMENTS Metal layer pattern forming methods according to the present invention will now be described with reference to FIGS. 4 through 6. First Embodiment In this embodiment, the present invention is applied to the patterning of a BLM (ball limiting metal) layer consisting of a metal layer when a solder ball bump is formed. As shown in FIG. 4A, in the substrate to be processed 3 (wafer) used as a sample in this embodiment, a passivation layer (a surface protecting layer) 10 of polyimide, silicon nitride film or the like is formed on an aluminum electrode pad 9 of a semiconductor base 8, and a connection hole 11 of a predetermined size is formed, and further, a photoresist layer 12 is formed thereon and patterned so as to have an opening diameter larger than that of the passivation layer 10. Here, the patterning of the photoresist layer 12 is performed in a thickness of 3 μm, which is not less than double the thickness of the BLM layer (1.2 μm) to be formed next. Then, this wafer is conveyed to a plane parallel plate type RF plasma processing apparatus as shown in FIG. 3, which is connected to a metal layer forming apparatus under high vacuum condition. By way of example, a premetal-layer-formation process was conducted under the following conditions: Argon gas flow rate: 30 sccm Argon gas pressure: 5 mTorr (0.67 Pa) High-frequency electric power: 300 w (13.56 MHz) Processing time: 6 minutes As a result of this plasma processing, the surface layer of the photoresist layer 12 of the substrate to be processed 3 was subjected to Ar + ion irradiation, and the upper portion thereof protruded due to thermal expansion, with the cross section of the resist pattern being deformed into a protruding section 12a having an overhang configuration as shown in FIG. 4B. The maximum temperature of the wafer surface in the processing under these conditions was approximately 115° to 135° C. Next, this substrate to be processed 3, which had undergone pre-film-formation process, was conveyed to a metal film formation apparatus such as a sputtering apparatus which is connected through a gate valve under a high vacuum condition, and, for example, a chrome layer having a thickness of 0.1 μm, a copper layer having a thickness of 1.0 μm, and a gold layer having a thickness of 0.1 μm were successively stacked one upon the other by sputtering to thereby form a BLM layer 13. This state is shown in FIG. 4C. No metal layer was formed on the side wall surface of the background resist pattern whose configuration was controlled so as to be an overhanging one by the above-described pre-metal-film-formation process, and the BLM layer 13 was divided between the opening portion on the electrode pad 9 and the resist layer 12. Then, the substrate to be processed 3 in this condition was immersed, for example, in a resist separation liquid composed of dimethyl sulfoxide (CH 3 ) 2 S O and N-methyl-2-pyrrolidone CH 3 NC 4 H 6 O (stirred in the solution heated to approximately 95° C. with the result that the unnecessary portion of the BLM layer that had been formed on the photoresist 12 was lifted off simultaneously with the separation of the resist, as shown in FIG. 4D, and, as shown in FIG. 4D, the BLM layer pattern 13a was completed in the predetermined place of the connection hole 11. Second Embodiment In this embodiment, the present invention is similarly applied to the BLM layer patterning when a solder ball bump is formed, the present invention being executed by applying a plasma processing apparatus using ICP (inductively coupled plasma) as the plasma generation source to the pre-film-formation process of the metal layer sputtering process. The substrate to be processed in this embodiment is the same as the one used in the first embodiment, which is shown in FIG. 4A. A description of the components which are the same as those of the first embodiment will be omitted. As in the case of the first embodiment, the patterning of the photoresist layer 12 is effected in a film thickness of 3 μm, which is not less than double the thickness of the BLM layer 13 to be formed next (1.2 μm). An example of the construction of the ICP processing apparatus to be used in the pre-metal-layer-formation process of this embodiment will be schematically described with reference to FIGS. 5 and 6. This apparatus includes a plasma processing chamber 2 formed of a dielectric material like quartz and an inductive coupling coil 14 that is wound a number of turns around the side wall thereof. The power of the plasma power source 15 is supplied to the plasma processing chamber 2 by the inductive coupling coil 14, where a high-density plasma 16 is generated. The substrate to be processed 3 is placed on the substrate stage 4, to which the power of a substrate bias power source 17 is supplied. Further, though not shown, the apparatus is naturally equipped with various other requisite components, such as a processing gas inlet hole, a vacuum discharge system, a gate valve, and a conveying system for the substrate to be processed. This apparatus is characterized in that it is capable of plasma excitation with great electric power by means of the large-sized multi-turn inductive coupling coil 14, making it possible to perform high-density plasma processing of in the order of 10 12 /cm 3 . Further, it has an advantage in that it allows control of the incident ion energy independently of the plasma generation due to the substrate bias power source 17. Further, in this embodiment, in order to improve the temperature control characteristics of the substrate to be processed 3, the substrate stage 4 is temperature-controlled by a refrigerant circulating inside the stage 4, as shown in FIG. 6, and the stage surface allows a satisfactory heat transfer between it and the substrate to be processed 3 by virtue of the electrostatic adsorption due to the electrostatic chuck 18 and gas cooling. Due to this arrangement, it is possible to accurately control the wafer temperature during the pre-metal-layer-formation process even when continuous processing is performed. As an apparatus equivalent to the ICP used in this embodiment, it also is possible to use TCP (transfer-coupled plasma), ECR (electron coupled resonance), helicon wave plasma, etc. By using these apparatuses, it is possible to obtain a plasma density of not less than 1×10 11 cm -3 but less than 1×10 14 cm 3 . Next, the substrate to be processed 3 shown in FIG. 4A is set on the stage 4, and, by way of example, pre-metal-layer-formation processing was conducted under the following conditions: Argon gas flow rate: 25 sccm Gas pressure: 1 mTorr Plasma power source: 1000 W (2 MHz) Substrate bias power: 200 V (13.56 MHz) Processing time: 45 seconds In the case of the plane parallel plate type plasma processing apparatus of the first embodiment described above, the application of RF power that is high to some degree or more in order to stably continue the discharge and secure the uniformity in the processing speed. This inevitably causes the substrate bias voltage (cathode fall voltage) to be set at a relatively high level. In this embodiment, in contrast, a plasma processing apparatus having two high-frequency power sources that are capable of independently controlling the substrate bias voltage and the plasma generation are used, so that the incident ion energy can be optimized without adversely affecting the discharge plasma. Thus, bonding to the background due to an excessive thermal transformation of the interior of the resist is not caused, making it possible to accurately set the substrate bias voltage so that the resist can be processed into an optimum configuration for lift-off. Further, since a high-density plasma source is used, the absolute amount of ions generated increases, and the condition setting under low pressure is possible, thereby making it possible to restrain the scattering of the incident ions. Thus, a reduction in processing time can be achieved even if the substrate bias voltage is reduced. Thus, in this embodiment, a substantial reduction in processing time can be achieved as compared to the first embodiment. As a result of this plasma processing, the surface layer of the photoresist layer 12 of the substrate to be processed 3 was subjected to Ar + ion irradiation as shown in FIG. 4B, as in the first embodiment, and the upper portion thereof was protruded due to thermal expansion, with the cross section of the resist pattern being deformed into an overhang-like configuration. The maximum temperature of the wafer surface attained in the processing under the conditions of this embodiment was approximately 115° C. to 135° C. After that, the metal layer formation was effected and lift-off was performed, with the result that a satisfactory pattern formation of the metal layer (BLM layer) was eventually realized as in the first embodiment. While the present invention has been described with reference to two embodiments, the present invention is in no way restricted to these embodiments, and it goes without saying that the sample structure, the processing apparatus, the processing conditions, etc. can be appropriately selected without departing from the scope of the present invention. By adopting the present invention, in the pre-metal-layer-formation process to be performed when patterning the metal layer by the lift-off (separation) of the photoresist, bonding to the background due to an excessive thermal transformation imparted to the resist can be prevented, and the resist can be processed to an optimum condition for lift-off, thereby realizing a satisfactory BLM layer pattern formation for solder ball bump formation. Thus, in accordance with the present invention, designing can be conducted on the basis of a further refined design rule, which is very effective in the production of a semiconductor device which is required to exhibit a high integration, high performance and high reliability.	Disclosed is a metal layer pattern forming method which easily allows lift-off. The thickness of the photoresist layer is not less than double the thickness of the metal layer, and the maximum temperature that the surface of the substrate to be processed attains ranges from 100° C. to 150° C. Through appropriate improvement of the quality of the photoresist layer, bonding to the background is prevented and the lift-off is facilitated.	8
RELATED APPLICATIONS [Not Applicable] FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [Not Applicable] MICROFICHE/COPYRIGHT REFERENCE [Not Applicable] BACKGROUND OF THE INVENTION The present invention generally relates to context management in a healthcare environment. In particular, the present invention relates to use of rules-based context management to improve diagnostic reading and workflow in a healthcare environment. A clinical or healthcare environment is a crowded, demanding environment that would benefit from organization and improved ease of use of imaging systems, data storage systems, and other equipment used in the healthcare environment. A healthcare environment, such as a hospital or clinic, encompasses a large array of professionals, patients, and equipment. Personnel in a healthcare facility must manage a plurality of patients, systems, and tasks to provide quality service to patients. Healthcare personnel may encounter many difficulties or obstacles in their workflow. A variety of distractions in a clinical environment may frequently interrupt medical personnel or interfere with their job performance. Furthermore, workspaces, such as a radiology workspace, may become cluttered with a variety of monitors, data input devices, data storage devices, and communication device, for example. Cluttered workspaces may result in efficient workflow and service to clients, which may impact a patient's health and safety or result in liability for a healthcare facility. Data entry and access is also complicated in a typical healthcare facility. Thus, management of multiple and disparate devices, positioned within an already crowded environment, that are used to perform daily tasks is difficult for medical or healthcare personnel. Additionally, a lack of interoperability between the devices increases delay and inconvenience associated with the use of multiple devices in a healthcare workflow. The use of multiple devices may also involve managing multiple logons within the same environment. A system and method for improving ease of use and interoperability between multiple devices in a healthcare environment would be highly desirable. In a healthcare environment involving extensive interaction with a plurality of devices, such as keyboards, computer mousing devices, imaging probes, and surgical equipment, repetitive motion disorders often occur. A system and method that eliminate some of the repetitive motion in order to minimize repetitive motion injuries would be highly desirable. Healthcare environments, such as hospitals or clinics, include clinical information systems, such as hospital information systems (HIS) and radiology information systems (RIS), and storage systems, such as picture archiving and communication systems (PACS). Information stored may include patient medical histories, imaging data, test results, diagnosis information, management information, and/or scheduling information, for example. The information may be centrally stored or divided at a plurality of locations. Healthcare practitioners may desire to access patient information or other information at various points in a healthcare workflow. For example, during surgery, medical personnel may access patient information, such as images of a patient's anatomy, that are stored in a medical information system. Alternatively, medical personnel may enter new information, such as history, diagnostic, or treatment information, into a medical information system during an ongoing medical procedure. In current information systems, such as PACS, information is entered or retrieved using a local computer terminal with a keyboard and/or mouse. During a medical procedure or at other times in a medical workflow, physical use of a keyboard, mouse or similar device may be impractical (e.g., in a different room) and/or unsanitary (i.e., a violation of the integrity of an individual's sterile field). Re-sterilizing after using a local computer terminal is often impractical for medical personnel in an operating room, for example, and may discourage medical personnel from accessing medical information systems. Thus, a system and method providing access to a medical information system without physical contact would be highly desirable to improve workflow and maintain a sterile field. Imaging systems are complicated to configure and to operate. Often, healthcare personnel may be trying to obtain an image of a patient, reference or update patient records or diagnosis, and ordering additional tests or consultation. Thus, there is a need for a system and method that facilitate operation and interoperability of an imaging system and related devices by an operator. In many situations, an operator of an imaging system may experience difficulty when scanning a patient or other object using an imaging system console. For example, using an imaging system, such as an ultrasound imaging system, for upper and lower extremity exams, compression exams, carotid exams, neo-natal head exams, and portable exams may be difficult with a typical system control console. An operator may not be able to physically reach both the console and a location to be scanned. Additionally, an operator may not be able to adjust a patient being scanned and operate the system at the console simultaneously. An operator may be unable to reach a telephone or a computer terminal to access information or order tests or consultation. Providing an additional operator or assistant to assist with examination may increase cost of the examination and may produce errors or unusable data due to miscommunication between the operator and the assistant. Thus, a method and system that facilitate operation of an imaging system and related services by an individual operator would be highly desirable. A reading, such as a radiology or cardiology procedure reading, is a process of a healthcare practitioner, such as a radiologist or a cardiologist, viewing digital images of a patient. The practitioner performs a diagnosis based on a content of the diagnostic images and reports on results electronically (e.g., using dictation or otherwise) or on paper. The practitioner, such as a radiologist or cardiologist, typically uses other tools to perform diagnosis. Some examples of other tools are prior and related prior (historical) exams and their results, laboratory exams (such as blood work), allergies, pathology results, medication, alerts, document images, and other tools. For example, a radiologist or cardiologist typically looks into other systems such as laboratory information, electronic medical records, and healthcare information when reading examination results. Currently, a practitioner must log on to different systems and search for a patient to retrieve information from the system on that patient. For example, if a patient complains of chest pain, a chest x-ray is taken. Then the radiologist logs on to other systems to search for the patient and look for specific conditions and symptoms for the patient. Thus, the radiologist may be presented with a large amount of information to review. Depending upon vendors and systems used by a practitioner, practitioners, such as radiologists or cardiologists, have only a few options to reference the tools available. First, a request for information from the available tools may be made in paper form. Second, a practitioner may use different applications, such as a radiologist information system (RIS), picture archiving and communication system (PACS), electronic medical record (EMR), healthcare information system (HIS), and laboratory information system (LIS), to search for patients and examine the information electronically. In the first case, the practitioner shifts his or her focus away from a reading workstation to search and browse through the paper, which in most cases includes many pieces of paper per patient. This slows down the practitioner and introduces a potential for errors due to the sheer volume of paper. Thus, a system and method that reduce the amount of paper being viewed and arranged by a practitioner would be highly desirable. In the second case, electronic information systems often do not communicate well across different systems. Therefore, the practitioner must log on to each system separately and search for the patients and exams on each system. Such a tedious task results in significant delays and potential errors. Thus, a system and method that improve communication and interaction between multiple electronic information systems would be highly desirable. Additionally, even if systems are integrated using mechanisms such as Clinical Context Object Workgroup (CCOW) to provide a practitioner with a uniform patient context in several systems, the practitioner is still provided with too much information to browse through. Too much information from different applications is provided at the same time and slows down the reading and analysis process. There is a need to filter out application components that a user will not need in a routine workflow. Thus, a system and method which manage information provided by multiple systems would be highly desirable. Furthermore, if a technologist is performing a radiology or cardiology procedure, for example, the technologist typically accesses multiple applications to obtain information prior to the procedure. In a digital environment, information resides in a plurality of disparate systems, such as a RIS and a PACS. Currently, the technologist must access each system and search for the information by clicking many tabs and buttons before having access to all of the information needed to start the procedure. Often, such an effort by a technologist to obtain information for a procedure results in a decrease in productivity due to the time involve and/or a decrease in information quality due to the time involved to do a thorough search. Thus, a system and method which improve searchability and access to data would be highly desirable. Additionally, referring physicians use many computerized applications for patient care. In radiology, a physician may look at information from RIS, PACS, EMR, and Computer Physician Order Entry (CPOE), for example. The referring physician typically accesses multiple applications to get all of the information needed before, during and/or after the patient consult and follow-up. For example, in a digital environment, the referring doctor refers to a RIS for results from a current procedure, prior procedures, and/or a web-based image viewer, such as a PACS, for viewing any current and prior images. The doctor may access a CPOE to order any follow-up exams. The referring physician opens the RIS, PACS, and CPOE to search for the information by clicking many tabs and buttons before having access to the information. Thus, there is a need for a system and method which improve searchability and access to data. Thus, there is a need for a system and method to improve diagnostic reading and workflow in a healthcare environment BRIEF SUMMARY OF THE INVENTION Certain embodiments of the present invention provide a method and system for improved diagnostic reading and workflow in a healthcare environment using rules-based context management. In an embodiment, the system includes a plurality of information sources, wherein each of the plurality of information sources includes information. The system also includes a rules engine including at least one rule governing at least one of availability and presentation of information. In addition, the system includes a context manager for obtaining information from the plurality of information sources based on a query and filtering the information based on the at least one rule. In an embodiment, the information sources include an information system and/or an imaging system, for example. The system may also include an authentication module for authenticating access to at least one of the context manager and at least one of the plurality of information sources. In an embodiment, the system also includes a plurality of perspectives, where each perspective saves a relation with at least one of the plurality of information sources. A medical perspectives manager associates at least one information source with a perspective and allows a user to access the at least one associated information source using the perspective. In an embodiment, the rules engine includes a plurality of sets of rules for a plurality of groups. The rules engine may adapt the rule(s) based on a prior observation and/or user input, for example. In an embodiment, the context manager includes a plurality of rules-based contexts for a plurality of groups. Certain embodiments of a method for rules-based context management in a healthcare environment include sharing a context between information systems to connect a plurality of disparate information systems, retrieving information from at least one of the information systems based on a request, and filtering the information based on at least one rule. The method may also include defining a set of rules for filtering information from the information systems. Also, the method may include adapting the set of rules based on a prior observation and/or user input, for example. Additionally, the method may include selecting a context for retrieving the information. The method may include selecting a perspective for retrieving the information. In an embodiment, the method includes authenticating access to the information. Certain embodiments of a method for providing rules-based context management in a healthcare environment include creating at least one context for retrieving information from at least one information source, defining set of at least one rule for processing information, and allowing retrieval of information in the context(s) using the rule(s). The method may further include selecting a context from a plurality of contexts for retrieving information. Also, the method may include selecting a set of rules from a plurality of rules for processing information. The method may include adapting at least one rule based on a prior observation and/or user input, for example. The method may also include selecting a perspective for organizing retrieved information. In an embodiment, a computer-readable storage medium includes a set of instructions for a computer. The set of instructions includes a context management routine for defining a context coordinating a plurality of information sources, a rules engine routine for defining rules for processing information, and an information retrieval routine for forming an information query in the context and filtering the information based on the rules. The set of instructions may also include a perspectives routine for organizing the information for a user. BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS FIG. 1 illustrates a rules-based context management system used in accordance with an embodiment of the present invention. FIG. 2 illustrates a flow diagram for a method for improved diagnostic reading and workflow using rules-based context management in accordance with an embodiment of the present invention. The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, certain embodiments are shown in the drawings. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates a rules-based context management system 100 used in accordance with an embodiment of the present invention. The system 100 includes a rules engine 110 , a context manager 120 , and a plurality of information systems 130 , 131 , 132 , 133 . Information systems 130 - 133 may include a radiology information system (RIS) 130 , a picture archiving and communication system (PACS) 131 , a laboratory information system (LIS) 132 , and/or an electronic medical record (EMR) 133 , for example. The context manager 120 may be a clinical context object workgroup (CCOW) context manager, for example. The components of the system 100 may communicate via wired and/or wireless connections on one or more processing units, such as computers, medical systems, storage devices, custom processors, and/or other processing units. In an embodiment, the components of the system 100 are integrated into a single unit. The system 100 may be used to provide an integrated solution for application execution and/or information retrieval based on rules and context sharing. For example, context sharing allows information and/or configuration options/settings, for example, to be shared between system environments. Rules, for example, may be defined dynamically and/or loaded from a library to filter and/or process information generated from an information system and/or an application. The context manager 120 may be used to create patient and/or examination context sharing between information systems 130 - 133 . The context manager 120 may be an integrated or standalone software and/or hardware manager for context sharing between information systems 130 - 133 . The manager 120 may also provide relevant information within a patient and/or examination context based on rules. The context manager 120 may be a context manager such as CCOW, which uses an HL7 standard to support user and patient context sharing, or other context management system. Context sharing allows information from a plurality of systems to be combined in a single context or setting. For example, information on a particular patient may be extracted from a RIS, a PACS, and an EMR. The manager 120 works in conjunction with the rules engine 110 to extract information from systems 130 - 133 using extensible markup language (XML), simple object access protocol (SOAP), and/or other protocol, for example. The manager 120 and/or rules engine 110 may include a user interface, such as a graphical or voice command user interface, to allow a user to access components and features of the system 100 . In an embodiment, the context manager 120 includes and/or communicates with an authentication unit. The authentication unit may include software and/or hardware to verify a user's right to access one or more of the manager 120 , information systems 130 - 133 , and/or rules engine 110 . In an embodiment, authentication via the context manager 120 allows access to relevant information systems 130 - 133 and other applications for a user. If a user logs on to a system running the context manager 120 , a rule may be created and saved to log onto certain information systems 130 - 133 to access the user's preferred information. For example, a physician may prefer to look at labs, allergies and medication. Thus, a rule is created to log on to an LIS and HIS for labs, allergies and medication when the physician logs onto the system 100 . Applications, such as LIS and HIS, are moved to a correct patient context. Along with the context and based on rules, the LIS and HIS display pertinent information for a patient. For example, the applications display all lab results for the patient for a specific date. The applications also display all complete blood count (CBC) data for the patient for the date. As another example, rules may filter patient alert data for a specific date range and/or specific disease type. Thus, from the same workstation using the system 100 , a user may look at a RIS for relevant prior reports, search a PACS for relevant prior images, and/or examine a LIS and/or HIS for specific information, all based on context sharing and rules. As a result, diagnosis and diagnostic reports may be reached more quickly and more accurately. Rules for the context manager 120 may be created in a variety of ways. Rules may be generated automatically by the rules engine 110 based on preset parameters and/or observed data, for example. Rules may also be created by a system administrator or other user. Rules may be changed to provide different information for diagnosis. Rules also may be manually and/or automatically adapted based on experiences. Applicable rules from the rules engine 110 are transmitted to the context manager 120 . A user may log on any one of the connected systems and access information found on all of the connected systems through context sharing. The information may be filtered for easier, more effective viewing. Thus, a user may access desired information from a plurality of systems with unwanted information removed. In operation, a user, such as a radiologist or cardiologist, accesses the context manager 120 via a RIS/PACS system, for example. RIS and PACS systems may be integrated into a single system, for example, with shared patient and exam contexts. Thus, the user access relevant prior history for a patient (e.g., images and reports). For example, the radiologist may log on to the RIS/PACS system which retrieves and integrates information from different systems based on an EMR number. Automatic login to one or more systems/applications may be accomplished via context management. However, a large quantity of information may result from such context sharing. All of the information may be linked at the patient level, for example. The context manager 120 provides relevant prior history and other information, for example, based on rules from the rules engine 110 . Rules may be applied to images, reports, and other data. Rules-based context management allows information to be provided to a practitioner for a patient based on certain rules. Rules may be used by a practitioner and/or system to define a context for information. For example, if a radiologist only wishes to see lab results for two months, a rule may be created in the rules engine 110 to only provide the previous two months of lab results to the radiologist. Rules may be created based on time period, examination type, disease type, system type, etc. Rules may be predefined and/or created on the fly by the practitioner. Rules may also be automatically generated and/or modified by the rules engine 110 based on practitioner usage patterns and/or preferences, for example. For example, a referring physician preparing for a patient looks at a requested procedure, prior clinical conditions of the patient, protocols from a radiologist, and relevant prior images, current reports and current images. The rules engine 110 allows the physician to set up a rule for exams to provide procedure and report information from an RIS, clinical conditions from an EMR, protocols from the RIS, and current images and relevant prior images from a PACS, for example. When the physician meets with the patient, the rules engine 110 may trigger the context manager 120 with information that determines a context. The context is driven by the context manager 120 to connected applications and relayed to the physician's desktop. Thus, by selecting an exam, the referring physician sees a variety of information. For example, a computed tomography (CT) technologist preparing to scan a patient reviews at a requested procedure, prior clinical conditions of the patient, protocols from a radiologist, and relevant prior images. The technologist may use the rules engine 110 to define a rule for CT exams to provide procedure information from a RIS, clinical conditions from an EMR, protocols from the RIS, and relevant prior images from a PACS. When the technologist selects to begin the procedure, the rules engine 110 triggers the context manager 120 with information deciding the context for the exam. The context is driven by the context manager 120 to connected applications and related to the technologist's desktop to enable the technologist to have access to relevant information by selecting an exam. In an embodiment, the manager 120 may work together with a perspectives management system for handling multiple applications and workflow. The perspectives management system allows various perspectives to be defined which save workflow steps and other information for a particular user. Perspectives may be used to save visual component positioning information and interactions based on workflow, for example. Perspectives allow relevant information to be presented to a user. One example of a perspectives management system is described in a U.S. patent application filed on Oct. 1, 2004, entitled “System and Method for Handling Multiple Radiology Applications and Workflows”, with inventors Prakash Mahesh and Mark Ricard, which is herein incorporated by reference in its entirety. FIG. 2 illustrates a flow diagram for a method 200 for improved diagnostic reading and workflow using rules-based context management in accordance with an embodiment of the present invention. First, at step 210 , one or more rules are defined. Rules may be defined for a particular user or group of users (e.g., surgeons, radiologists, cardiologists, etc.), for a particular use or group of uses (e.g., image-guided surgery, radiology reading, structured reporting, examination, etc.), for a particular modality (e.g., x-ray, ultrasound, magnetic resonance imaging, etc.), and/or for a particular platform (e.g., a PACS, an integrated RIS/PACS, an imaging system, etc.), for example. Rules may be defined by software, by a user, and/or by a system administrator, for example. New rules may be created, and/or existing rules may be modified. Then, at step 220 , a user initiates access to a system, such as an information system or clinical workstation. Access to a system may include authentication at the system and/or authentication at additional connected systems. Authentication may occur manually and/or automatically based on input or stored information. Next, at step 230 , a user queries the system for information. For example, the user queries the system regarding a patient. At step 240 , context sharing is used to obtain information regarding the query from a variety of connected systems. For example, context sharing is used to obtain patient information from an EMR, PAC, RIS, HIS, and LIS. Then, at step 250 , the queried information is filtered based on the defined rules applicable to the user. That is, rules defined for the user, group of users, modality, and/or platform, for example, are used to refine and customize the data delivered to the user. The information may be filtered with rules before and/or after the information is obtained from the plurality of information sources. Thus, the user is presented with relevant, requested information. The filtered information may be displayed for the user, stored, and/or routed to another program, for example. In an embodiment, the user may organize the information presented based on perspectives which save visual component positioning and interactions based on workflow, for example. At step 260 , rules may be modified based on commands executed at the system and/or manual modification by the user. For example, rules may automatically be refined by the context manager 120 and rules engine 110 based on observed requests and options selected by the user. Additionally, for example, the user may manually add, delete, and/or modify rules stored in the rules engine 110 . Thus, certain embodiments unify a variety of information systems and other applications. Certain embodiments filter information available to a user based on rules. Certain embodiments provide rules-based context sharing among a plurality of systems including RIS, PACS, CVIS (Cardiovascular Information System), EMR, LIS, HIS, and/or other applications. Certain embodiments facilitate increased productivity of a radiologist, cardiologist, or other user reading exams that use relevant information from other information systems. Increased productivity includes a speed in which a diagnosis may be performed and an accuracy of reports produced based on the diagnosis. In certain embodiments, rules allow information and workflow to be filtered. A user may store and toggle between contexts and sets of rules. In certain embodiments, a user may toggle between sets of rules without touching a keyboard or mouse using a technique such as voice command and/or gaze tracking. Alternatively, a user may toggle between rules using a single click from a mousing device or a button. Thus, certain embodiments allow a user to view only the information he or she wants in the workflow he or she wants. Certain embodiments allow a user to manage the number of applications being accessed at a given time. Certain embodiments provide a rules and context based integration between information systems and applications. While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.	Certain embodiments of the present invention provide a method and system for improved diagnostic reading and workflow in a healthcare environment using rules-based context management. In an embodiment, the system includes a plurality of information sources, wherein each of the plurality of information sources includes information. The system also includes a rules engine including at least one rule governing at least one of availability and presentation of information. In addition, the system includes a context manager for obtaining information from the plurality of information sources based on a query and filtering the information based on the at least one rule. In an embodiment, the information sources include an information system and/or an imaging system, for example.	6
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for producing purine-arabinosides, particularly by an enzymatic process. 2. Description of the Prior Art Purine-arabinosides (9-(β-D-arabinofuranosyl)-purines) have potential utility as agricultural chemicals or medicinal agents. For example, it has been reported that adenine arabinoside, one of the purine arabinosides has been used successfully to treat several diseases caused by the herpes virus including chickenpox and shingles. As to known methods for producing the purine arabinosides, several chemically synthetic methods have been proposed, (J. Org. Chem. 27, 3274, (1962); J. Org. Chem. 28, 3004 (1963); J. Org. Chem, 32, (1976); Tetrahedron Letters 1970, 4673; and Japanese Published Exmined Patent Application No. 7271/1972). It is further reported that adenine arabinoside is produced when Streptomyces antibioticus is cultured in conventional culture media (Japanese Published Examined Patent Application No. 41558/1972). SUMMARY OF THE INVENTION It has been found that purine arabinosides are produced in aqueous reaction media from an arabinose donor such as uracil arabinoside or D-arabinofuranose-1-phosphate and a purine-source such as adenine, hypoxanthine, adenosine and adenosine-5'-monophosphate by the action of an enzyme produced by various bacteria. A commercially applicable method for producing purine arabinosides has now been provided by (a) holding at a temperature in the range from 40° to 70° C. in an aqueous medium an arabinose donor selected from the group consisting of D-arabinofuranose-1-phosphate, and the compound having Formula I on a nucleotide thereof; and a purine source selected from the group consisting of unsubstituted or 2,6 and/or 8-substituted purine and its ribofuranoside, ribofuranotide, deoxyribofuranoside or deoxyribofuranotide, in the presence of an effective amount of an enzyme produced by a bacterium and capable of transarabinosylation from the arabinose donor to the unsubstituted or 2,6 and/or 8-substituted purine of the purine source, whereby the β-D-arabinofuranosyl radical is attached to the 9-position of the unsubstituted or 2,6 and/or 8-substituted purine; and (b) recovering the produced 9-(β-D-arabinofuranosyl)-unsubstituted or 2,6 and/or 8-substituted purine. ##STR1## X represents O, S or NH; Y represents OH, NH 2 , SH or SR(R is a lower alkyl group); and Z represents H, halogen, NO 2 , CH 3 or CH 2 OH. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: FIG. 1 is the NMR spectrum of the crystalline product obtained in Example 5. FIG. 2 is the ultra-violet spectrum of the product obtained in Example 5. FIG. 3 is the IR spectrum of the product obtained in Example 5. FIG. 4 is the NMR spectrum of the crystalline product obtained from Example 6. FIG. 5 is the UV spectrum of the product obtained from Example 6. FIG. 6 is the IR spectrum of the product obtained from Example 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The arabinose donors of this invention are D-arabinofuranose-1-phosphates of, the compounds of formula I, or the phosphate of the compound showing formula I. The specimens of the arabinose donors are shown in the Examples of this invention. The purine sources of this invention are unsubstituted or 2,6 and/or 8-substituted purine and its ribofuranoside, deoxyribofuranoside or deoxyribofuranotide. The 2,6 and/or 8-substituted purine used in this invention as the purine source can be prepared by the following method: the Ribofuranoside of a 2,6 and/or 8-substituted purine is held with the enzyme of this invention in an aqueous medium containing 0.1 M KH 2 PO 4 at 60° C. for 24 hours. When the 2,6 and/or 8 substituted purine of the originally used 2,6 and/or 8-substituted purine ribofuranoside, and D-ribofuranose-1-phosphate or D-ribose derived from the above ribofuranoside are produced in the aqueous medium, the 2,6 and/or 8-substituted purine can then be used as the purine source. The substituents of the 2,6 and/or 8-substituted purines are, for example, halogen, hydroxyl, amino, lower alkyl, alkoxyl, aryl, aralkyl, mercapto, alkylamino, alkylmercapto, alkylsulfonyl, alkylsulfenyl, carboxyl, alkoxycarbonyl, cyano, and nitro radicals. The D-arabinofuranose of the arabinose donor is enzymatically transferred to and attached to 9-position of the unsubstituted or 2,6/or 8-substituted purine of the purine source. Thus, the product of this invention is 9-(β-D-arabinofuranosyl)-unsubstituted or 2,6 and/or 8-substituted purine. The bacterial enzyme capable of transarabinosylation from the arabinose donor to unsubstituted or 2,6 and/or 8-substituted purine of the purine source is produced mainly in the bacterial cells and is present to a small extent in the supernatant of the culture liquids. The bacteria capable of producing the enzyme belong, as found so far, to the genera Pseudomonas, Flavobacterium, Achromobacter, Salmonella, Citrobacter, Escherichia, Klebsiella, Enterobacter, Aeromonas, Serratia, Erwinia, Proteus, Xanthomonas, and Bacterium. Specimens of the bacteria are: ______________________________________Pseudomonas stutzeri NRRL B-11346 (FERM-P 4170),Flavobacterium rhenanum NRRL B-11343 (CCM 298),Flavobacterium acidoficum ATCC 8366,Flavobacterium proteus ATCC 12841,Achromobacter lacticum NRRL B-11340 (CCM 69),Salmonella typhimirim NRRL B-11347 (FERM-P3735),Citrobacter freundii ATCC 8090,Citrobacter freundii ATCC 6750,(Citrobacter intermedium)Escherichia coli ATCC 9637,Escherichia aurescens ATCC 12814,Klebsiella pneumoniae ATCC 9621,(Enterobacter aerogenes)Serratia liquefaciens ATCC 14460,(Enterobacter liquefaciens)Enterobacter aerogenes ATCC 13048,Aeromonas punctata ATCC 11163,Aeromonas salmonicida ATCC 14174,Serratia marcescens IFO 3048,Erwinia carotovora NRRL B-11342 (CCM 872),Erwinia amylovara NRRL B-11341 (CCM 1017),Erwinia herbicola ATCC 14537,Proteus vulgaris NRRL B-11345 (FERM-P3394),Proteus rettgeri NRRL B-11344 (FERM-P3395),Bacterium cadaveris IFO 3731, andXanthomonas citri NRRL B-11348 (FERM-P3396).______________________________________ In order to produce the enzyme using the bacteria as mentioned above, the bacteria are cultured in or on conventional culture media. The culture media contain conventional carbon sources, nitrogen sources, inorganic ions, and when required minor organic nutrients such as vitamins and amino acid. Usual manner can be applied to culture the bacteria in the conventional media, that is, the bacteria are cultured aerobically preferably at a pH of a range from 4 to 9 and a temperature of a range from 25° to 40° C. As the enzyme source, intact cells, culture liquids containing the cells are used preferably. Additionally, cells dried with acetone, freeze-dried cells, homogenized cells, cells treated with supersonic waves, cells treated with toluene, surfactants or lysozyme are employed giving desirable results. Moreover protein fractions having the enzyme activity capable of transarabinosylation from the arabinose donor to unsubstituted or 2,6 and/or 8-substituted purine of the purine source can be used preferably as the enzyme source. It is expected that there is more than one enzyme participating in the production of the purine arabinosides. The production of the purine arabinosides can be carried out by holding in the culture media of the bacteria the purine source and the arabinose donor. In this case, the arabinose donor and purine source are added into the culture media after the bacteria has grown sufficiently, and thereafter the temperature is maintained at 40° C. to 70° C. The production of the purine arabinoside can be also carried out by contacting the purine source and arabinose-donor with the cells or the enzyme sources as mentioned above in aqueous reaction media other than culture media. Thus, in this invention, "aqueous medium" means culture medium or reaction medium (reaction mixture). The reaction media are maintained preferably at a temperature from 40° C. to 70° C., and at a pH of 4 to 10 for 5 to 100 hours. The reaction temperature (40° C. to 70° C.) of this invention is specific in the point that the temperature is higher than the ordinarily enzyme reaction temperature, and it is critical. The purine arabinosides produced in the culture media or the reaction media can be recovered by conventional manners such as ion exchange method or crystallization technique. Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. EXAMPLE 1 An aqueous culture medium of pH 7.2 was prepared which contained, per deciliter, 0.5 g yeast extract, 1.0 g peptone, 0.5 g bouillon, and 0.5 g NaCl. Five ml batches of the aqueous culture medium were placed in test tubes, and heated to sterilize. Each one loopful inocculum of the bacteria listed in Table 1 was transferred into each batch of the aqueous culture medium. Cultivation was carried out at 30° C. for 36 hours with shaking. The cells produced in the culture liquid were collected by centrifugation and washed with physiological saline. The cells thus obtained (50 mg(wet)/ml) were suspended in samples of 0.05 M phosphate buffer of pH 7.0, and 0.5 ml of the suspension of the cells was mixed with 0.5 ml of reaction mixture of pH 7.5 containing 0.5 g/dl uracil arabinoside, 0.2 g/dl hypoxanthine and 50 mg/dl KH 2 PO 4 . Each mixture was held at 60° C. for 15 hours, and thereafter heated to 100° C. for 5 minutes. Each product in the reaction mixture was identified as 9-β-D-arabinofuranosylhypoxanthine (hypoxanthine arabinoside) by high speed liquid chromatography, and the amounts of the hypoxanthine arabinoside in the reaction mixture were determined by high speed liquid chromatography, and are shown in Table 1. TABLE 1______________________________________microorganism hypoxanthine arabinosideused accumulated mg/dl______________________________________NRRL B-11343 3.7ATCC 8366 6.6ATCC 12841 6.7NRRL B-11340 5.7NRRL B-11347 7.5ATCC 8090 11.3ATCC 6750 13.2ATCC 9637 10.5ATCC 12814 17.0ATCC 9621 126.0ATCC 14460 17.0ATCC 14174 36.0ATCC 11163 4.1IFO 3048 23.0NRRL B-11342 14.0NRRL B-11341 18.0ATCC 14537 21.0NRRL B-11345 9.6NRRL B-11344 2.4NRRL B-11348 11.0IFO 3731 12.0NRRL B-11346 7.5ATCC 13048 55.7______________________________________ EXAMPLE 2 In the method shown in Example 1, adenine was substituted for hypoxanthine, and the amounts of adenine arabinoside shown in Table 2 were produced in the reaction mixture. EXAMPLE 3 In the method shown in Example 1, cytosine arabinoside was substituted for uracil arabinoside, and the amounts of hypoxanthine arabinoside shown in Table 3 were produced in the reaction mixture. EXAMPLE 4 In the method shown in Example 1, adenine riboside-5'-monophosphate was substituted for hypoxanthine, and the amounts of adenine arabinoside shown in Table 4 were accumulated in the reaction mixture. TABLE 2______________________________________microorganism adenine arabinosideused accumulated mg/dl______________________________________ NRRL B-11343 4.5ATCC 8366 8.2ATCC 12841 8.0NRRL B-11340 6.5NRRL B-11347 8.6ATCC 8090 13.3ATCC 6750 15.0ATCC 9637 10.6ATCC 12814 18.8ATCC 9621 132.0ATCC 14460 26.0ATCC 14174 41.0ATCC 11163 18.5IFO 3048 32.6NRRL B-11342 20.5NRRL B-11341 22.5ATCC 14537 31.5NRRL B-11345 26.3NRRL B-11344 28.6NRRL B-11348 13.5IFO 3731 21.2NRRL B-11346 8.6ATCC 13048 71.8______________________________________ TABLE 3______________________________________microorganism hypoxanthine arabinosideused accumulated mg/dl______________________________________NRRL B-11343 4.2ATCC 8366 5.5ATCC 12841 8.2NRRL B-11340 2.6NRRL B-11347 4.8ATCC 8090 6.5ATCC 6750 10.3ATCC 9637 6.3ATCC 12814 3.6ATCC 9621 82.1ATCC 14460 15.0ATCC 14174 20.5ATCC 11163 0.8IFO 3048 13.6NRRL B-11342 2.6NRRL B-11341 8.7ATCC 14537 15.0NRRL B-11345 8.1NRRL B-11344 0.5NRRL B-11348 0.8IFO 3731 10.6NRRL B-11346 3.2ATCC 13048 40.2______________________________________ TABLE 4______________________________________microorganism adenine arabinosideused accumulated mg/dl______________________________________NRRL B-11343 3.8ATCC 8366 5.6ATCC 12841 7.2NRRL B-11340 3.5NRRL B-11347 8.3ATCC 8090 10.2ATCC 6750 8.6ATCC 9637 5.5ATCC 12814 6.9ATCC 9621 82.3ATCC 14460 13.5ATCC 14174 25.5ATCC 11163 9.6IFO 3048 21.5NRRL B-11342 15.5NRRL B-11341 11.5ATCC 14537 18.3NRRL B-11345 12.6NRRL B-11344 15.8NRRL B-11348 8.3IFO 3731 14.5NRRL B-11346 8.5ATCC 13048 49.6______________________________________ EXAMPLE 5 A hundred ml batches of the aqueous culture medium shown in Example 1 were placed in a 500 ml shaking flask and heated to sterilize. Klebsiella pneumoniae ATCC 9621 was inocculated in the aqueous culture medium and cultured at 30° C. for 36 hours with shaking. Cells produced in the resultant culture liquid were collected by centrifugation, and 30 g (wet) of the cells was put into 1 l of the reaction mixture of pH 7.0 containing 1.5 g 2-methylhypoxanthine, 7.3 g uracil arabinoside and 3.4 g KH 2 PO 4 . The reaction mixture was held at 60° C. for 36 hours. Cells were removed from the reaction mixture by centrifugation, the supernatant was passed through cation exchange resin ("Amberlite CG-120"), and the resin was washed with 0.1 N ammonium acetate (pH 6.8). After eluting with 0.1 N ammonium hydroxide, the eluate was evaporated and cooled, and 710 mg crystals were obtained. The crystalline product was determined as 9-(β-D-arabinofuranosyl)-2-methylhypoxanthine(2-methylhypoxanthine arabinoside) by its NMR spectrum, UV spectrum, IR spectrum, and elemental analysis. Elemental analysis: Calculated; C:46.8%, H:5.0%, N:19.8%. Found; C:46.5%, H:5.1%, N:19.5%. NMR spectrum: shown in FIG. 1. UV spectrum: shown in FIG. 2. IR spectrum: shown in FIG. 3. EXAMPLE 6 Thirty grams of the cells obtained in Example 4 were put into 1 l of reaction mixture containing 1.7 g 2-chloro-hypoxanthine, 7.3 g uracil arabinoside, and 3.4 g KH 2 PO 4 , and the reaction mixture was held at 60° C. for 36 hours. After removing the cells from the reaction mixture, the supernatant was passed through anion exchange resin ("Dowex IX4"), and the resin was washed with 0.1 N ammonium acetate of pH 6.8. After eluting with 0.1 N ammonium acetate of pH 4.0, the eluate was evaporated, and charged on "Sephadex G-10", and developed with water. The eluate portions showing the first of two peaks peak of UV absorption of the two was collected, evaporated and cooled. Then, 326 mg crystals were obtained. The crystalline product was determined as 9-(β-D-arabinofuranosy)-2-chlorohypoxanthine(2-chlorohypoxanthine arabinoside) by its NMR spectrum, UV spectrum, IR spectrum, elemental analysis and Beilstein test. Elemental analysis: Calculated; C:39.68, H:3.66, N:18.51. Found; C:39.42, H:3.72, N:18.25. NMR spectrum: shown in FIG. 4 UV spectrum: shown in FIG. 5 IR spectrum: shown in FIG. 6 Beilstein test: positive (green) EXAMPLE 7 In the method shown in Example 1, 2-methylhypoxanthine or 2-chlorohypoxanthine was substituted for hypoxanthine, and the amounts of 2-methylhypoxanthine arabinoside or 2-chlorohypoxanthine arabinoside shown in Table 5 were accumulated in the reaction mixture. EXAMPLE 8 In the method shown in Example 1, 0.2 g/dl hypoxanthine was replaced with 0.4 g/dl inosine, and the amounts of hypoxanthine arabinoside shown in Table 6 were produced in the reaction mixture. EXAMPLE 9 A hundred ml of the aqueous culture medium shown in Example 1 was placed in a 500 ml shaking flask, heated to sterilize, and inoculated with Aeromonas salmonicida ATCC 14174. Cultivation was carried out at 30° C. for 36 hours with shaking. Cells produced in the resultant culture liquid were collected by centrifiguation, and 2.0 g (wet weight) of the cells were put into 100 ml reaction mixture of pH 7.5 containing 100 mg hypoxanthine, 300 mg uracil arabinoside and 50 mg KH 2 PO 4 . The reaction mixture was then held at 60° C. for 15 hours. Twenty five mg of crystals of hypoxanthine arabinoside were obtained from the reaction mixture. TABLE 5______________________________________ 2-chlorohypo- 2-methylhypoxan- xanthine thine arabinoside arabinoside accumulated accumulatedmicroorganism mg/dl mg/dl______________________________________NRRL B-11343 2.1 0.5ATCC 8366 3.4 0.8ATCC 12841 4.0 2.1NRRL B-11340 5.5 2.5NRRL B-11347 4.8 2.8ATCC 8090 8.7 3.6ATCC 6750 9.5 8.2ATCC 9637 4.7 5.1ATCC 12814 12.0 10.5ATCC 9621 80.5 51.6ATCC 14460 18.5 11.3ATCC 14174 21.6 10.0ATCC 11163 0.8 0.05IFO 3048 15.4 10.8NRRL B-11342 2.5 0.1NRRL B-11341 12.0 10.5ATCC 14537 15.5 12.1NRRL B-11345 0.6 0.05NRRL B-11344 8.2 0.5NRRL B-11348 12.5 0.8IFO 3731 21.6 2.1NRRL B-11346 15.3 10.3ATCC 13048 40.2 28.7______________________________________ TABLE 6______________________________________ hypoxanthine arabinosidemicroorganism used accumulated mg/dl______________________________________NRRL B-11343 2.8ATCC 8366 3.6ATCC 12841 5.5NRRL B-11340 4.3NRRL B-11347 6.2ATCC 8090 8.8ATCC 6750 7.4ATCC 9637 1.6ATCC 12814 13.6ATCC 9621 83.3ATCC 14460 6.2ATCC 14174 16.8ATCC 11163 0.9IFO 3048 15.3NRRL B-11342 6.8NRRL B-11341 10.2ATCC 14537 8.9NRRL B-11345 8.5NRRL B-11344 0.8NRRL B-11348 7.2IFO 3731 5.8NRRL B-11346 3.3ATCC 13048 40.4______________________________________ EXAMPLE 10 Klebsiella pneumoniae ATCC 9621 was cultured in the manner shown in Example 9. Cells in the resultant culture liquid were collected by centrifugation, and 2 g (wet weight) of the cells were suspended in 100 ml reaction mixture of pH 7.5 containing 100 mg hypoxanthine, 300 mg cytosine arabinoside, 50 mg KH 2 PO 4 , and the reaction mixture was held at 60° C. for 15 hours. The cells in the reaction mixture were removed by centrifugation, and a concentrate of the supernatant was passed through anion exchange resin ("Dowex-1" OH form, pH 6.8). After eluting with 0.1 N formic acid of pH 4.0, the eluate was passed through "Sephadex G-10". Eluate (250 ml) obtained by eluting with water was concentrated and the concentrate was added with methanol and cooled to form crystals of the product. After re-crystallization with water, 35 mg purified crystals were obtained. The crystalline product was identified with authentic hypoxanthine arabinoside by its NMR spectrum, IR spectrum and UV spectrum. EXAMPLE 11 Klebsiella pneumoniae ATCC 9621 was cultured by the same manner as in Example 9, and cells were collected by centrifugation. Hypoxanthine in the reaction mixture in Example 9 was replaced with adenine, and the reaction mixture was held at 60° C. for 15 hours. The supernatant of the reaction mixture was concentrated to 20 ml. Upon cooling the concentrate, 80 mg crystals were obtained. The crystalline product was identified with authentic adenine arabinoside by its NMR spectrum, IR spectrum, and UV spectrum. EXAMPLE 12 Erwinia hervicola ATCC 14537 was cultured by the same manner as in Example 9, and the cells produced were collected by centrifugation. The cells thus obtained (2 g (wet weight)/dl) were suspended in 100 ml of a reaction mixture of pH 7.5 containing 100 mg/dl adenine, 300 mg/dl cytosine arabinoside and 50 mg KH 2 PO 4 , and held at 60° C. for 15 hours. After removing the cells from the reaction mixture, the reaction mixture was concentrated to 20 ml, and cooled. The crystals thus obtained were recrystallized with water and 55 mg purified crystals were obtained. The crystalline product was identified with adenine arabinoside by its NMR spectrum, IR spectrum and UV spectrum. EXAMPLE 13 Cells (5 g (wet)/dl) of Aeromonas salmonicida ATCC 14174 were suspended in 100 ml batches of a reaction mixture containing 30 mM cytosine arabinoside, 25 mM KH 2 PO 4 , and 10 mM of one of the purines shown in Table 7. The reaction mixtures were placed in test tubes and held at 60° C. for 15 hours. Newly formed product having UV absorption in the resultant reaction mixture was separated by liquid chromatography. The eluate of the chromatography was concentrated and added with ethanol, whereby crystals were formed in the eluate. From NMR spectra and UV spectra of the purified crystalline products, the products were ascertained as the arabinosides of the respective purines used as the starting materials. Conversion ratio of the purine arabinosides from purine source were determined by measuring molecular extinction coefficient, and are shown in Table 7. TABLE 7______________________________________ Conversion ratioStarting material Product (%)______________________________________xanthine xanthine arabinoside 15guanine guanine arabinoside 8purine purine arabinoside 236-mercaptopurine 6-mercaptopurine arabinoside 82,6-diaminopurine 2,6-diaminopurine arabino- 38 side6-mercaptoguanine 6-mereaptoguanine arabino- 7 side2-methylhypoxanthine 2-methylhypoxanthine 35 arabinoside2-chlorohypoxanthine 2-chlorohypoxanthine 18 arabinoside______________________________________ EXAMPLE 14 Cells (5 g (wet)/dl) of Klebsiella pneumoniae ATCC 9621 were suspended in 100 ml batches of a reaction mixture placed in test tubes, containing 30 mM uracil arabinoside, 25 mM KH 2 PO 4 , and one of the purine sources (10 mM) listed in Table 8, and the reaction mixture was held at 60° C. for 15 hours. Newly formed product having UV-absorption in the resultant reaction mixture was separated by liquid chromatography. The eluate of the chromatography was concentrated and added to ethanol, whereby crystals were formed in the eluate. From NMR spectra of the purified crystalline products, the products were ascertained as the arabinoside of the respective purine sources used as starting materials. Conversion rate of purine arabinosides from the purine sources used was determined by measuring the molecular extinction, coefficient, and are shown in Table 8. TABLE 8______________________________________ Conversion ratioStarting material Product (%)______________________________________xanthine xanthine arabinoside 65guanine guanine arabinoside 20purine purine arabinoside 366-mercaptopurine 6-mercaptopurine arabinoside 82,6-diaminopurine 2,6-diaminopurine arabino- 52 side6-mercaptoguanine 6-mercaptoguanine arabino- 5 side______________________________________ EXAMPLE 15 In the method shown in Example 5, 2-methylhypoxanthine was replaced with 2-ethylhypoxanthine. The resultant reaction mixture was charged on thin-layer silica-gel, and the chromatogram was developed with water-saturated butanol. The part of Rf 0.4 having absorption at 260 nm on the thin-layer was collected, and suspended in 0.1 NHCl, and silica-gel was removed from the suspension. When the supernatant of the suspension was made 6 N with HCl and boiled for 10 minutes, orcinol-ferric chloride reaction of the boiled suspension became positive, and 2-ethylhypoxanthine was found in the boiled suspension by paper-chromatography. Thus, it is suggested that 2-ethylhypoxanthine arabinoside was produced in the reaction mixture. EXAMPLE 16 Cells of Klebsiella pneumoniae ATCC 9621 were obtained by the same manner as in Example 9, suspended in 0.5 M phosphate buffer of pH 7.5 to obtain 100 g (wet)/l, and treated with super supersonic. A hundred ml of a reaction mixture, of pH 7.5 containing 50 ml/dl the supernatant, 500 mg/dl uracil arabinoside-5-monophosphate, 100 mg/dl hypoxanthine and 30 mg/dl KH 2 PO 4 , was held at 60° C. for 15 hours. Then the reaction mixture was centrifuged to remove precipitates, and the supernatant was passed through cation exchange resin ("Chromobead C-2"). Elution was made with 0.3 N formic acid, and the eluate was charged on anion exchange resin ("Dowex 1×4"). Hypoxanthine arabinoside was eluted by gradient elution with ammonium formate of pH 9 to 3 and 8 mg of crystals were obtained from the eluate. EXAMPLE 17 One ml of a reaction mixture containing, per milliliter, 0.2 ml of the supernatant shown in Example 16. 10 mg uracil arabinoside, 2 mg KH 2 PO 4 , 2 mg of one of the purine sources shown below was held at 60° C. in a test tube for 15 hours, and heated at 100° C. for 5 minutes. After removing precipitates in the reaction mixture, the reaction mixture was subjected to paper chromatography, and the spot having UV-absorption and having a Rf value different from that of the purine sources used as the starting material was cut, and put into 0.1 N HCl. Then the 0.1 N HCl was made 6 N by adding concentrated HCl after removing filter paper, and boiled for 10 minutes, arabinose was found by an ferric chloride reaction in the boiled 6 NHCl. Thus, it is expected that arabinosides of the following sources used as the starting materials were produced in the reaction mixtures: 6-chloropurine 2-chlorohypoxanthine 2-aminopurine 2-methylthiohypoxanthine 8-chloroadenine 6-mercaptopurine 6-methylthiopurine 2-amino-6-mercaptopurine 6-carboxypurine 8-bromoadenine EXAMPLE 18 In the method shown in Example 16, uracil arabinoside-5'-monophosphate was replaced with cytocine arabinoside-5'-monophosphate. In the resultant reaction mixture, hypoxanthine arabinoside was found. TABLE 9______________________________________microorganism hypoxanthine arabinosideused accumulated mg/dl______________________________________NRRL B-11343 2.8ATCC 8366 5.5ATCC 12841 6.3NRRL B-11340 6.0NRRL B-11347 5.2ATCC 8090 8.8ATCC 6750 10.6ATCC 9637 8.5ATCC 12814 12.3ATCC 9621 103.6ATCC 14460 12.5ATCC 14174 29.3ATCC 11163 4.0IFO 3048 24.0NRRL B-11342 15.2NRRL B-11341 17.6ATCC 14537 22.3NRRL B-11345 15.6NRRL B-11344 3.2NRRL B-11348 10.6IFO 3731 18.3NRRL B-11346 8.2ATCC 13048 48.5______________________________________ EXAMPLE 19 In the method shown in Example 1, D-arabinofuranose-1-phosphate was substituted for uracil arabinoside, and the amounts of hypoxanthine arabinoside shown in Table 9 were accumlated in the reaction mixture. EXAMPLE 20 In the method shown in Example 19, one of the purine sources listed in Table 10 was substituted for hypoxanthine, and newly formed product having UV-absorption in the resultant reaction mixture was separated by preparative high speed liquid chromatography. The eluate of the chromatography was concentrated and added to ethanol, whereby crystals were formed in the eluate. From NMR spectra and UV spectra of the crystalline products, the products were ascertained as the arabinosides of the respective purine sources used as the starting materials. The conversion ratio of the purine sources used to the purine arabinosides was determined by measuring the molecular extention coefficient and shown in Table 10. TABLE 10______________________________________ Conversion ratioStarting material product (%)______________________________________xanthine xanthine arabinoside 15guanine guanine arabinoside 8purine purine arabinoside 236-mercaptopurine 6-mercaptopurine arabinoside 82,6-diaminopurine 2,6-diaminopurine arabino- 38 side6-mercaptoguanine 6-mercaptoguanine 7 arabinoside2-methylhypoxanthine 2-methylhypoxanthine 35 arabinoside2-chlorohypoxanthine 2-chlorohypoxanthine 18 arabinoside______________________________________ EXAMPLE 21 Klebsiella pneumoniae ATCC 9621 was cultured by the same manner as in Example 9, and the cells produced were collected by centrifugation. 20 mg of the cells obtained were suspended in 1 ml of a reaction mixture of pH 7.0 containing 1.5 mg of adenine. 10 mg of one of the pyrimidine arabinosides listed in Table 11, and 3.4 mg of KH 2 PO 4 , and the reaction mixture was held at 60° C. for 15 hours. Cells were removed from the reaction mixture by centrifugation. Adenine arabinoside accumulated was identified by high speed liquid chromatography. TABLE 11______________________________________ arabinose donor______________________________________4-thiouracil arabinofuranoside4-(S-methyl-)thiouracil arabinofuranoside2-thiouracil arabinofuranoside5-nitrouracil arabinofuranoside5-hydroxymethyluracil arabinofuranosideisocytosine arabinofuranoside5-fluorouracil arabinofuranoside5-bromouracil arabinofuranoside5-Iodouracil arabinofuranosidethymine arabinofuranoside______________________________________ EXAMPLE 22 In the method shown in Example 11, adenine in the reaction mixture was replaced with 200 mg adenylic acid, and the reaction mixture was held at 60° C. for 15 hours. The supernatant of the reaction mixture was concentrated to 30 ml. Upon cooling the concentrate, 48 mg crystals were obtained. The crystalline product was identified with authentic adenine arabinoside by its NMR spectrum IR spectrum, and UV spectrum. EXAMPLE 23 In the method shown in Example 11, adenine in the reaction mixture was replaced with 150 mg guanosine, and the reaction mixture was held at 60° C. for 15 hours. The crystals of 2-(β-D-arabinofuranosyl)guanine (guanine arabinoside) (28 mg) were obtained from the supernatant of the resulted reaction mixture. EXAMPLE 24 In the method shown in Example 13, adenosine, deoxyadenosine, deoxyadenylic acid, guanylic acid, deoxyguanylic acid, xanthosine, deoxyxanthosine, deoxyinosine or deoxyinosinic acid were used in place of hypoxanthine as the purine source. From the above adenine source, adenine arabinoside was formed in the reaction mixture and separated by the usual manner. From the above guanine source, guanine arabinoside was formed. From the above xanthine source, the xanthine arabinoside was formed. From the hypoxanthine source, hypoxanthine arabinoside was formed. Having now fully described this invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention set forth herein.	Purine-arabinosides and a method for making purine-arabinosides are disclosed. The method comprises contacting an arabinose donor and a purine source in the presence of an effective amount of enzyme produced by a bacterium and capable of transarabinosylation from the arabinose donor to the purine source, whereby a 9-(β-D-arabinofuranosyl)-purine is produced.	2
CROSS-REFERENCE TO RELATED APPLICATIONS This is a divisional application of U.S. application Ser. No. 14/311,474, filed 23 Jun. 2014, entitled METHOD OF CREATING A SPRING BRASSICA NAPUS and issued 12 May 2015 as U.S. Pat. No. 9,029,630; which is a continuation application of U.S. application Ser. No. 13/375,358, filed 30 Nov. 2011, entitled METHOD OF CREATING A SPRING BRASSICA NAPUS and issued 24 Jun. 2014 as U.S. Pat. No. 8,759,608; which is a national phase entry of International Application No. PCT/US2010/036911, filed 1 Jun. 2010, entitled METHOD OF CREATING A SPRING BRASSICA NAPUS ; Which claims the benefit of U.S. Provisional Application No. 61/217,513, filed 31 May 2009, entitled METHOD OF CREATING A SPRING BRASSICA NAPUS . Each of the foregoing applications is incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates generally to breeding of Brassica napus . The invention has particular utility in creating spring B. napus lines from winter B. napus lines. BACKGROUND Brassica napus is grown commercially to produce edible oil that is low in saturated fat. In Europe, B. napus is commonly referred to as rapeseed or rape. Most B. napus commercially produced in North America is canola, which by definition must produce seed that yields oil having less than 2% erucic acid and meal that contains no more than 30 micromoles of the following glucosinolates per gram of air-dry, oil-free solid: 3-butenyl glucosinolate, 4-pentenyl glucosinolate, 2-hydroxy-3 butenyl glucosinolate, and 2-hydroxy-4-pentenyl glucosinolate. As used herein, a “non-canola” B. napus line is one which does not meet this definition, e.g., because the seeds produce oil with too much erucic acid or have too high a glucosinolate level. Most B. napus lines are typically classified as either spring lines or winter lines. Winter lines are commonly planted in the autumn and flower in the spring after a period of vernalization over the winter. Spring lines do not require vernalization to flower and are commonly planted and harvested in the same growing season. Winter lines are common in Europe, but most winter lines fare poorly in the colder winters of Canada and the northern United States. As a consequence, most B. napus grown commercially in North America are spring lines. Although open-pollinated B. napus lines remain quite common, commercial production of spring B. napus increasingly employs hybrid lines. Hybrid lines tend to have higher yields due to heterosis or “hybrid vigor”. This heterosis is more pronounced the more distant the genetic relationship between the parent B. napus lines. For this reason, several researchers have suggested crossing winter and spring B. napus lines to produce higher-yielding hybrids. For example, U.S. Pat. No. 6,069,302 (“Osborn”, the entirety of which is incorporated herein by reference) proposes crossing a spring B. napus line with a B. napus line that is itself derived from at least one winter line. DETAILED DESCRIPTION Definitions As used herein, a “winter B. napus ” is a B. napus that has a winter flowering habit, i.e., that does not germinate, initiate vegetative growth, undergo gametogenesis and flower in less than 77 days when subjected to the following conditions, which are referred to below as “standardized growing conditions” or simply “SGCs”: the seeds are planted in 4-inch plastic pots in a general growth medium (e.g., Premier Pro-Mix BX potting soil from Permier Horticulture of Quebec, Canada) in an environmentally controlled growth cabinet (e.g., Conviron ATC60 from Controlled Environments Limited of Winnipeg, Manitoba) with a 16 hour photoperiod, a day time temperature of 20 degrees Celsius and night time temperature of 17 degrees Celsius, watered daily as needed and a 20:20:20 (NPK) liquid fertilizer added three times weekly. As used herein, a “spring B. napus ” is a B. napus that has a spring flowering habit, i.e., that will germinate, initiate vegetative growth, undergo gametogenesis and flower in no more than 55 days when subjected to the aforementioned standardized growing conditions. A “rapid-cycle Brassica rapa ”, as that term is used herein, is a B. rapa that has a rapid-cycle flowering habit, i.e., that will germinate, initiate vegetative growth, undergo gametogenesis and flower in no more than 20 days when subjected to the standardized growing conditions detailed above. As it flowers in less than 55 days, a “rapid-cycle Brassica rapa ” may also be said to have a spring flowering habit. Overview Specific details of several embodiments of the disclosure are described below. One aspect of the present disclosure is directed toward a method for producing a modified Brassica napus . In accordance with this method, a first winter B. napus line is crossed with a rapid-cycle B. rapa line in a first cross, thereby producing an F1 modified B. napus plant that has a spring flowering habit. The rapid-cycle B. rapa line has a mean flowering time under standardized growing conditions of no greater than 20 days. After the first cross, seed from the F1 modified B. napus plant (or progeny thereof) is crossed with a second winter B. napus line in a second cross to produce a plant, which may be referred to as a first backcross (BC1) plant, that has a spring flowering habit. Another embodiment of the invention provides a method for producing a modified Brassica napus having a winter flowering habit. In this method, a first winter B. napus line is crossed with a rapid-cycle B. rapa line in a first cross, thereby producing an F1 modified B. napus plant that has a spring flowering habit. The rapid-cycle B. napus line has a mean flowering time under standardized growing conditions of no greater than 20 days. After the first cross, the F1 modified B. napus plant (or progeny thereof) is crossed with a second winter B. napus line in a second cross to produce a first backcross population. From the first backcross population, at least one first backcross (BC1) plant that has a spring flowering habit is selected. Thereafter, the BC1 plant or progeny thereof is crossed with a third winter B. napus line in a third cross to produce a second backcross plant population. From the second backcross plant population, at least one second backcross (BC-W) plant that has a winter flowering habit is selected. Producing F1 Spring B. napus Aspects of the invention are directed to the production of a spring modified B. napus line by crossing a winter B. napus line with a rapid-cycle Brassica rapa line. In a preferred embodiment, the winter B. napus line used in the cross will not germinate, initiate vegetative growth, undergo gametogenesis and flower at all unless subjected to vernalization. Although this is no guarantee, a line that is less prone to flower without vernalization may have a more distant genetic relationship to most common spring B. napus lines (defined below). As a consequence, one might predict that crossing such a winter B. napus line with a common spring a B. napus line would yield a hybrid with greater heterosis than would a winter line that flowers more readily. Several restriction fragmentation length polymorphisms (RFLPs) have been linked to specific vernalization-responsive flowering time loci. See, e.g., Ferreira, M. E., et al., “Mapping Loci Controlling Vernalization Requirement and Flowering Time in Brassica napus,” Theor. Appl. Genet. 98:727-732 (1995); see also Osborn, T. C. et al, “Comparison of Flowering Time Genes in Brassica rapa, B. napus , and Arabadopsis thaliana,” Genetics 146:1123-1129 (1997). These include vfn1, which was mapped as a quantitative trait locus (QTL) of Linkage Group (LG) 9; vfn2, which was mapped as a QTL of LG12; and vfn3, which was mapped to LG16. Osborn identifies suitable RFLP loci to distinguish winter and spring vfn1 and vfn2 alleles and provides sequences that may be used for PCR probes to screen for winter vfn1 and vfn2 alleles. Winter B. napus lines suitable for use in the present method may (but need not have winter alleles for one, two, or three of the vfn1, vfn2, and vfn3 loci. In one useful implementation, the winter a B. napus line used in the present method has a homozygotic winter vfn1 allele. A wide variety of suitable winter B. napus lines are known and available to breeders from a variety of sources. A non-limiting, partial list of winter B. napus lines that are expected to work well in connection with the disclosed process would include Columbus, Jetton, Darmor, Campala, Casino, Bristol, Plainsman, Jet Neuf, Wichita, Major, Samourai, and Ceres. Some of these winter lines are European B. napus lines while others are North American winter lines. As explained below, spring modified B. napus lines of the present disclosure may be useful in creating hybrid spring B. napus lines. If such hybrid B. napus lines employ a parent line derived primarily from North American sources, using European winter B. napus lines in the present method may provide a rich source for diverse genetics that may further enhance heterosis. In one embodiment, the winter B. napus line is a canola-quality line, i.e., it produces seed with oil having no more than 2% erucic acid and meal that contains no more than 30 micromoles of the previously identified glucosinolates per gram of meal. This can help quickly produce a canola-quality modified B. napus in accordance with the invention. In another useful approach, however, the winter B. napus line is not a canola line, e.g., because the glucosinolate level in its meal is too high. Many European varieties of B. napus do not meet the definition of canola. As explained below, using such varieties in this first cross can improve heterosis in further hybrid breeding. Suitable rapid-cycle B. rapa lines are available under the trade name Wisconsin Fast Plants and available from multiple sources, including Carolina Biological Supply Company of Burlington, N.C., US (“Carolina”). The Fast Plant Standard seed from Carolina is expected to work well, though the other seed types offered by Carolina may be useful for specific breeding goals. In one implementation, this cross employs a female winter B. napus line and a male rapid-cycle B. rapa line. The female line may exhibit cytoplasmic male sterility or may be emasculated manually. The pollen from the B. rapa line would then be available to pollinate the B. napus line. In other embodiments, the B. rapa may be the female line (e.g., by manual emasculation) and the B. napus may be the male line. As noted above, the present disclosure provides a method in which a winter B. napus line is crossed with a rapid-cycle B. rapa line to produce at least one F1 plant that is a modified B. napus line. B. napus is commonly understood to be an allopolyploid with an “A” genome traceable to B. rapa and a “C” genome traceable to Brassica oleracea . Crossing B. napus and B. rapa in accordance with embodiments of the present invention, therefore, is believed to modify the A genome of the winter B. napus line while leaving the C genome largely intact. Those skilled in the field may refer to the F1 plant as a B. napus or as a “modified” B. napus , with “modified” possibly being further characterized as a “partially reconstituted” or “species interspecific”. For purposes of clarity, the term “modified B. napus ” shall be deemed to encompass plants that result from a cross of a B. napus line and a B. rapa line, as well as progeny of such a cross. Furthermore, the term B. napus as used herein shall encompass both conventional and modified B. napus. A surprisingly high percentage of the F1 plants that come from the described a B. napus×B. rapa cross are spring B. napus . It is worth noting that the scope of a spring flowering habit encompasses a rapid-cycle flowering habit, as well. Spring F1 plants of the present invention could, but certainly need not, have a rapid-cycle flowering habit. Many commercially desirable F1 plants will have a spring flowering habit, but not a rapid-cycle flowering habit, i.e., will germinate, initiate vegetative growth, undergo gametogenesis and flower in 21-55 days under SGCs. Although rapid flowering is a desirable characteristic, rapid-cycle a B. rapa may have a rather short time from planting to full maturity. The Wisconsin Fast Plant Program indicates that the Wisconsin Fast Plants, for example, mature within about 40 days after planting. Shorter growing seasons for B. napus are typically associated with reduced yield and/or lower oil quality, so a very short time to maturity may be expected to adversely impact yield and/or oil quality. Aspects of the present invention, however, yield spring B. napus lines that are expected to have very good agronomic and oil quality characteristics. The resultant F1 hybrid may or may not produce canola-quality seed. If a non-canola B. napus is used as the winter line in making the F1, there is a good chance that some or all of the resultant F1 plants will produce seed that fail to meet the canola definition stated above. In one implementation, the F1 plants may be screened to identify seed that both has a spring flowering habit and produces canola-quality seed. As noted above. Osborn and others have proposed crossing winter and spring B. napus lines and selecting spring B. napus plants from the resultant F1 population. Unfortunately, many of the plants in the F1 population are not spring B. B. napus . Osborn suggests using genetic screening of vfn1, vfn2, and/or vfn3 loci to identify plants that are expected to have a spring growth habit (as that term is used in the Osborn patent). Such screening may be less expensive than growing all of the F1 population to see which plants will have a spring flowering habit, but it adds complexity to a breeding program. Aspects of the present invention provide a surprisingly high spring conversion efficiency, where “spring conversion efficiency” is the percentage of the F1 population resulting from the winter B. napus ×rapid-cycle B. rapa cross that has a spring flowering habit. In certain implementations, this spring conversion efficiency is at least 80%, desirably 85% or more, and preferably at least 90%. As explained in connection with the examples below, winter B. napus ×rapid-cycle B. rapa crosses have yielded an astounding 100% spring conversion rate in this first cross, i.e., all of the F1 plants have a spring flowering habit. Backcrossing Spring B. napus with Winter B. napus In accordance with a further embodiment, the F1 seeds produced by the winter B. napus ×rapid-cycle B. rapa cross outlined above (or progeny of the F1 seed) are crossed again with a second winter B. napus line to yield a first backcross plant (BC1). The F1 seed used in this second cross desirably has a spring flowering habit. At least a significant percentage, if not all or substantially all, of the BC1 plants may have a spring flowering habit. In one embodiment, this second cross is a true backcross, i.e., the same winter B. napus used in the first cross is used in the second cross with the F1 seed. In other embodiments, the first winter B. napus line used in the first cross is different from the second winter B. napus line used in the second cross. This may not be considered a true “backcross” as that term is conventionally used, but the term backcross as used herein in connection with producing the present BC1 plant (and subsequent BCn plants) is intended to encompass a cross of a spring modified B. napus F1 (or BCn) plant as described above with any suitable winter B. napus line. Even if there is no recurrent parent in the cross pollination, the term “backcross” is intended to reflect the cross a spring modified B. napus or its progeny “back” with any winter line. The resultant BC1 seed may be subjected to any number of additional “backcrosses” with winter B. napus . Preferably, the BC1 seed used in such an additional backcross has a spring flowering habit; if the BC1 population includes some plants that do not have a spring flowering habit, one can test the BC1 seed and select only those plants that have a spring flowering habit. In some embodiments, each of these backcrosses is a true backcross, i.e., the winter line is the same in the first cross to produce the F1 seed and in each of the subsequent crosses. In other embodiments, the winter line used in a subsequent cross may differ from one or more of the winter line(s) used in the previous crosses. For example, the BC1 seed may be crossed with a third winter B. napus line to produce a second backcross plant (BC2) and the third winter B. napus line may be different from one or both of the first and second B. napus lines used to produce the F1 and BC1 plants, respectively. This process may be repeated to create a whole series of backcross generations, BC1, BC2, BC3, . . . BCn. In each backcross, the winter parent may be a recurring parent from the preceding cross (a true backcross). Alternatively, two or more different winter lines may be used in the backcrosses. In each such backcross, a backcross population may be created and plants having a spring flowering habit may be selected from that population. Further Hybrid Breeding—Spring In another further embodiment, seed produced by crossing the winter B. napus line and rapid-cycle B. rapa line as noted above can be crossed in a second hybrid cross with another spring B. napus to produced a second hybrid B. napus, referred to herein as a F′1 hybrid, with a spring flowering habit. In this embodiment, the F1, BC1, BC2, . . . BCn seed described above, or progeny of such seed, may be used in the second hybrid crossing step. If so desired, seed from a suitable F1 or BCn plant having a spring flowering habit may be selfed one or more times to increase the amount of available seed. The selected seed (whether a selected F1 or BCn plant or the higher volume of seed from selfing) may be crossed with an existing spring B. napus line to form F′1 plants and plants having a spring flowering habit may be selected from the F′1 population. Such an approach can be particularly advantageous in breeding a commercial canola line, for example. As noted above, the winter B. napus line selected for the initial cross to form the F1 hybrid may be a non-canola line. The genetic differences of such lines from most commercial spring canola lines will tend to be greater than such differences from most winter canola lines. At least some of this genetic difference is expected to be found in the F1 seed and in backcrosses and other progeny thereof. When the F1 seed is crossed with an existing spring B. napus line, the genetic differences between the two parent lines may enhance heterosis, producing F′1 plants that have better yield and/or vigor. In one specific embodiment, therefore, the F1 line (or its progeny) selected for the second hybrid cross is a non-canola line. This non-canola F1 line is then crossed with a spring B. napus line that meets the canola definition and the resultant F′1 plants may be screened to select those that are canola quality. As explained above, crossing B. napus and B. rapa in accordance with the present invention is believed to modify the A genome of the winter B. napus line while leaving the winter line's C genome largely intact. This means that a significant majority of the winter line's genetics will be carried forward into the modified B. napus F1 plants that result from B. napus×B. rapa cross. In contrast, crossing spring×winter B. napus as proposed by Osborn results in modification of both the A and C genomes. Osborn teaches selecting a F1 plant from such a cross that has a spring growth habit and crossing that F1 plant with another spring line. This further dilutes the winter germplasm in the spring-stable line. Creating a spring modified B. napus and “backcrossing” that F1 plant (or its progeny) with another winter line, however, reinforces the winter genetics in the A genome while retaining a winter-derived C genome. Methods in accordance with embodiments of the invention thus introduce significant new germplasm from winter lines' C genome into a spring B. napus breeding program. This largely untapped pool of germplasm is expected to increase heterosis in spring B. napus hybrids such as the F1 plants noted above. As heterosis is associated with increased yield, this is expected to enable higher-yielding B. napus varieties. Further Hybrid Breeding—Winter Aspects of the invention can also be used to substantially speed up a winter B. napus breeding program. In accordance with one such method, a spring BC1 B. napus such as that described above is crossed with a winter line to form a backcross population. At least one second backcross plant that has a winter flowering habit is selected from that backcross population; this winter plant is referred to below as a BC-W to note its winter flowering habit. As a result, the breeding program takes a winter B. napus , creates a spring B. napus in which much of the winter C genome is believed to be intact, and then converts that spring B. napus back into a winter B. napus . Particularly if the first and second backcrosses are true backcrosses employing the same winter line used in the first cross with the rapid cycle B. rapa , this can leave some key genetics in the winter line intact through the complete cycle. This embodiment process has particular commercial significance if multiple crosses are conducted using plants with a spring flowering habit before selecting the BC-W line with the winter flowering habit. As noted above, a series of backcross generations—BC1, BC2, . . . BCn—may be created. The spring conversion efficiency of these backcrosses remains fairly high even through multiple generations, so one can continue to select a plant from the backcross population that has a spring flowering habit. Because most winter B. napus lines require vernalization, the time from planting to maturity for a winter B. napus is significantly longer than that for a spring B. napus . This means that spring breeding programs can take advantage of more greenhouse cycles per year than a similar winter breeding program, reducing the total time to develop a desired trait. Employing the present embodiment, however, a winter breeder can achieve much the same greenhouse cycle times as a spring breeding program by using the BC1-BCn spring B. napus generations described above. As each of these “backcrosses” permits the introduction of another winter B. napus line, the development time of the winter B. napus traits is greatly reduced. Once the breeder has developed such a spring B. napus with the desired traits, that spring B. napus can be crossed with another winter B. napus to create a backcross population and a resultant plant having a winter flowering habit may be selected from that population. This new winter B. napus line can then be used in the breeder's standard winter breeding program. Because the rapid-cycle B. rapa appears to impact only the A genome in the F1 generation and the C genome from the winter parent(s) appears to be largely intact, a winter breeder can carry many of the traits of interest from his or her winter lines through multiple generations of spring breeding. When the breeder selects a plant with a winter flowering habit (referred to as BC-W above) from a backcross population, therefore, there appears to be a good likelihood of successfully carrying forward the developed trait from the spring backcross generations into the BC-W plant and its progeny. EXAMPLES Aspects of certain methods in accordance with embodiments of the invention are illustrated in the following examples. Example 1 F1 Hybrid Cross Seeds of three winter B. napus lines—Columbus, Jetton, and Darmor—were planted and stored in cold conditions for three months for vernalization before being moved to a greenhouse. Fast Plant Standard seed from Carolina, identified below as FPS, was found to flower in 18 days at SGCs so it was determined to have a rapid-cycle flowering habit. Another B. rapa line. AcBoreal, was found to flower at 27 days at SGCs, so it has a spring flowering habit and is not a rapid-cycle B. rapa line. Each of the three winter B. napus lines were crossed with each of the B. rapa lines to make 5 plants of each cross. The winter B. napus lines were male sterile (they were emasculated or exhibited genetic cytoplasmic male sterility) and served as the female parent; the B. rapa lines were used as the male parent. The resultant F1 populations of each cross were grown under SGCs to determine their time to flowering. The time to the earliest flowering was noted for those plants that did flower; if no flowers were seen within 4 months at SGCs, the plant as noted as non-flowering. The results are shown in Table 1. TABLE 1 Female Days of Parent Male Flowering Earliest (winter Parent Total Plants Flower Flowering B. napus ) ( B. rapa ) Plant ID Plants (%) (SGCs) Habit Columbus FPS F1-C 5 5 (100%) ~30-35 Spring AcBoreal 5 0 Non-flowering Winter Jetton FPS F1-J 5 5 (100%) ~35-40 Spring AcBoreal 5 0 Non-flowering Winter Darmor FPS F1-D 5 5 (100%) ~30-35 Spring AcBoreal 5 0 Non-flowering Winter The spring conversion efficiency results for these crosses are remarkable. Crossing the winter B. napus lines with AcBoreal, a B. rapa with a spring flowering habit, produced an F1 population in which every single plant had a winter flowering habit, demonstrating a spring conversion efficiency of 0% (0 of 5 plants). Every F1 plant produced by crossing the rapid-cycle B. rapa FPS line with the same winter B. napus lines had a spring flowering habit, showing a remarkable 100% spring conversion efficiency (5 of 5 plants). This 100% spring conversion efficiency is impressive in its own right, but is made even more remarkable in comparison to the cross with AcBoreal, which itself has a spring flowering habit but did not yield a single F1 plant with a spring flowering habit. Example 2 Backcross 1 (BC1) Seed from one of the F1-C plants (Columbus×FPS cross) and one of the F1-J plants (Jetton×FPS cross) were then backcrossed to the original parent line, i.e., the F1-C was backcrossed with Columbus and the F1-J was crossed with Jetton. Twenty plants of each cross were produced. In each instance the winter B. napus line was used as the male and the F1 seed produced in Example 1 was used as the female. The resultant backcrossed seed (BC1) was planted and grown at SGCs and the time to the earliest flowering was noted for those plants that did flower; if no flowers were seen within 4 months at SGCs, the plant as noted as non-flowering. The results are shown in Table 2. TABLE 2 Female Parent Days of (Winter Male Plant Total Flowering Earliest B. napus ) Parent ID Plants Plants (%) Flower (SGCs) Columbus F1-C BC1-C 20 8 (40%) ~30-43 Jetton F1-J BC1-J 20 1 (5%) ~40 Example 3 Backcross 2 (BC2) Seed from the plant with the shortest flowering time for each backcross in Example 2 was then used as the male line in a cross with a female winter line. The Jetton backcross (BC1-J) was backcrossed to Jetton and the Columbus backcross (BC1-C) was “backcrossed” with a variety of different winter lines, as noted in Table 3. Ten to twenty-five plants of each cross were produced, also as noted in Table 3. The resultant backcrossed seed (BC1) was grown at SGCs and the time to the earliest flowering was noted for those plants that did flower; if no flowers were seen within 4 months at SGCs, the plant was noted as non-flowering. TABLE 3 Female Days of Parent Flowering Spring Plants Earliest (Winter Male Total Plants (percentage of Flower B. napus ) Parent Plant ID Plants (%) total plants) (SGCs) Columbus BC1-C BC2-C 20 15 (75%) 12 (60%) 30 Jetton BC1-J BC2-J 25 20 (80%) 18 (72%) 31 Campala BC1-C F1(BC2)-A 20 18 (90%) 17 (85%) 32 Casino BC1-C F1(BC2)-B 20 18 (90%) 13 (65%) 34 Bristol BC1-C F1(BC2)-C 20 19 (95%) 16 (80%) 33 Plainsman BC1-C F1(BC2)-D 10 9 (90%) 8 (80%) 32 Jet Neuf BC1-C F1(BC2)-E 20 20 (100%) 20 (100%) 28 Wichita BC1-C F1(BC2)-F 20 20 (100%) 20 (100%) 27 The results of this experiment show that the spring conversion efficiency remains quite high even though the male parent is already a backcross. All of the backcrosses had a spring conversion efficiency of at least 60%, with the entire population resulting from two of the crosses having a spring flowering habit. This suggests that a substantial majority of the winter genetics can be retained in a BC2 generation seed that has a spring flowering habit. Example 4 Backcross 3 (BC3) Seed that flowered in Example 2 was used as the male parent in a cross with a winter line. In each case, a true backcross was made, e.g., BC2-C was crossed with Columbus. In addition, the earliest-flowering plant of the Wichita cross in Example 2 (designated F1(BC2)-F) was backcrossed with different winter varieties, as noted below in Table 4. Twenty plants of each such cross were grown at SGCs and the time to the earliest flowering was noted for those plants that did flower; if no flowers were seen within 4 months at SGCs, the plant as noted as non-flowering. For purposes of comparison, a known spring B. napus , Westar, was also planted under SGCs and the days to flower were noted. TABLE 4 Days of Female parent Total Earliest (Winter B. napus ) Male Parent Plant ID Plants Flower (SGCs) Columbus BC2-C BC3-C 20 46 Jetton BC2-J BC3-J 20 50 Campala F1(BC2)-A BC1(BC3)-A 20 ~80 Casino F1(BC2)-B BC1(BC3)-B 20 56 Bristol F1(BC2)-C BC1(BC3)-C 20 47 Plainsman F1(BC2)-D BC1(BC3)-D 20 52 Jet Neuf F1(BC2)-E BC1(BC3)-E 20 52 Wichita F1(BC2)-F BC1(BC3)-F 20 37 Eric F1(BC2)-F F1(BC3)-G 20 48 Navajo F1(BC2)-F F1(BC3)-H 20 48 Contact F1(BC2)-F F1(BC3)-I 20 55 Mohican F1(BC2)-F F1(BC3)-J 20 46 Westar (spring) — — 5 37 Ten of the twelve backcrosses produced in accordance with an embodiment of the invention had a spring flowering habit. Of the two exceptions—the Campala backcross, BC1(BC3)-A, and the Casino backcross, BC1(BC3)-B—one had a flowering time of 56 days and very nearly qualifies as having a spring flowering habit. This suggests that even after 3 backcrosses to winter B. napus , the progeny of the winter B. napus ×rapid-cycle B. rapa cross disclosed herein can yield B. napus with a spring flowering habit. Although not shown in Table 4, the earliest-flowering plant of the Wichita backcross, F1(BC2)-F, population was also crossed with Westar and another spring B. napus line. The resultant F1 hybrid had improved vigor and appeared to have better yield, based on leaf size, larger pod size, and more seeds, when compared to either parent line. Example 5 Comparison to Spring×Winter B. napus Crosses A first spring×winter B. napus population was created by crossing a spring B. napus line with Columbus; as in Example 1, Columbus was male sterile and served as the female parent. The process used in Example 1 to produce F1-C, i.e., crossing the FPS rapid-cycle B. rapa and Columbus, was repeated. Five plants of each cross were produced and the resultant seed was grown at SGCs for at least 100 days. The plant with the earliest flowering time for the spring×Columbus cross (designated here as SW-F1) flowered in 43 days. The plant with the earliest flowering time for the FPS×Columbus cross (designated here as FPSC-F1) flowered in 31 days. SW-F1 and FPSC-F1 were each backcrossed with Columbus. Thirty plants of each cross were produced and the resultant seed was grown at SGCs for at least 100 days. The time to the earliest flowering was noted for those plants that did flower; if no flowers were seen in that time, the plant was noted as non-flowering. The results, including for each cross the shortest first flowering time for any of the 30 plants and the average first flowering time for those plants that did flower, are set forth in Table 5. TABLE 5 Shortest Days Average Flowering of Earliest Days of No. of Female Male Total Plants Flowering Earliest Spring Parent Parent Plants (%) (Under SGCs) Flowering Plants Columbus SW-F1 30 3 (10%) 83 89 0 Columbus FPSC-F1 30 18 (60%) 35 59 9 These results again highlight the surprising utility achieved by crossing rapid-cycle B. rapa with winter B. napus in accordance with aspects of the invention. The SWC-F1 parent in the backcross of Table 5 had a spring flowering habit that was reinforced through multiple generations of spring backcrosses and selection for spring flowering habit. All thirty of the backcrosses of that plant with a winter line had a winter flowering habit, i.e., the spring conversion efficiency of the cross was 0%, and the average number of days to earliest flowering of the three lines that did flower in the time allotted was almost 90 days. In contrast, the FPSC-F1 backcross yielded 18 plants that flowered in the same time, with one reaching first flower in just 35 days. Of those 18 plants, 9 had a spring flowering habit, representing a 30% spring conversion efficiency (9 of the 30 total plants), with an average among those 9 plants of 47 days to earliest flowering. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in a sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number respectively. When the claims use the word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. The above detailed descriptions of embodiments of the invention are not intended to be exhaustive or to limit the invention to the precise form disclosed above. Although specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein can also be combined to provide further embodiments. Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, percentages, reaction conditions, and so forth used in the specification and claims are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth are approximations that may depend upon the desired properties sought. In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless the above detailed description explicitly defines such terms. Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, percentages, reaction conditions, and so forth used in the specification and claims are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth are approximations that may depend upon the desired properties sought.	Crossing a winter B. napus line with a rapid-cycle B. rapa line has been discovered to provide an unexpectedly simple and efficient way to create a modified B. napus with a spring flowering habit. In one implementation, such a modified B. napus or its progeny is crossed with a second winter B. napus line to produce at plant having a winter flowering habit. This allows one to significantly shorten the development cycle for winter-flowering B. napus lines by conducting part of the breeding program with spring-flowering time cycles, then migrating the resultant germplasm back into a winter-flowering line.	0
FIELD OF THE INVENTION [0001] The present invention relates to plastic fences, and in particular, relates to molded plastic fence sections having reduced components for ease of assembly. BACKGROUND OF THE INVENTION [0002] Individual plastic extruded components for use as fence components are widely known and have had varying degrees of success in the market place. Plastic fence systems generally are lightweight, have good structural strength, can be reinforced, and are low maintenance. In today's busy environment, there is a desire to provide the end customer with a fence product which is easy to install and convenient to transport. To partially satisfy this demand, it is known to produce wood and/or plastic fence sections where various pieces of the fence section have been preassembled in the factory or at the distribution outlet to provide large complete fence sections. [0003] Unfortunately, due to the significant labour content required to assemble the fence sections, the cost is relatively high. In some cases, as a cost saving measure, the assembly can be done by the end purchaser, however, the extruded plastic fence sections, in particular, are relatively complicated and have a number of different extruded products which must be preassembled in a particular manner. [0004] There remains a need for a fence system which is more practical and which can be assembled in a relatively straightforward manner. SUMMARY OF THE INVENTION [0005] A plastic fence section for securement between two posts according to the present invention comprises two identical panels with each panel including a post engaging edge and a panel joining edge. The panels are reversible such that the post engaging end can be positioned at the right edge or at the left edge as required. Each panel includes at least two parallel horizontal chambers extending across the panels and joining with the respective horizontal chambers of the other panel. At least two reinforcing members extend through the horizontal channels and extend the length of the fence section. These horizontal reinforcing members are concealed within the fence section and allow suspension of the fence section between the end posts. [0006] According to an aspect of the invention, the fence section includes three horizontal chambers and three reinforcing members extending the length of the fence section and concealed within the fence section. [0007] According to a further aspect of the invention, the panel joining edge of each panel includes interlocking surfaces which interfit with the interlocking surfaces of the joining panel section. [0008] According to yet a further aspect of the invention, the panel joining edge is divided vertically to provide a male connecting portion to one side of the vertical division and a corresponding female connecting portion to the opposite side of the vertical division. [0009] A plastic privacy fence panel according to the present invention, comprises at least an upper hollow horizontal member and a lower horizontal member with both of these members extending the length of the fence panel and forming hollow cavities for receipt of a reinforcing member. The privacy fence panel comprises an upper top finished portion, a middle portion between the horizontal members and a bottom portion extending below the lower horizontal member. Each of the portions comprise a series of hollow chambers separated by pinch off regions of additional thickness relative to the thickness of the walls of the hollow chambers. The portions of the privacy fence panel cooperate with the horizontal members to provide a visual block across the width and height of the privacy fence panel. [0010] According to yet a further aspect of the invention, each panel is a single integral piece. [0011] According to yet a further aspect of the invention, each panel is manufactured by a blow molding technique. [0012] In yet a further aspect of the invention, each panel is symmetrical between opposed vertical edges of the panel relative to a vertical plane extending along the panel. [0013] According to yet a further aspect of the invention, each panel includes a post joining panel edge at one vertical edge of the panel and a slip joint edge on an opposite vertical edge of the panel. BRIEF DESCRIPTION OF THE DRAWINGS [0014] Preferred embodiments of the invention are shown in the drawings wherein: [0015] [0015]FIG. 1 is an exploded front perspective view showing two panels for securement between two posts; [0016] [0016]FIG. 2 is a partial front view of two panels; [0017] [0017]FIG. 3 is an exploded partial perspective view showing securement of a panel to a post; [0018] [0018]FIG. 4 is a partial horizontal section through a fence panel; [0019] [0019]FIG. 5 is a partial vertical section through one of the chambers for receiving a reinforcing member and through one of said vertically extending chambers; [0020] [0020]FIG. 6 is a vertical section similar to FIG. 5 but through a vertically extending pinch off region; [0021] [0021]FIG. 7 is an exploded partial perspective view of two panels being joined in the center of the fence section; [0022] [0022]FIG. 8 is a horizontal section through one of the horizontal reinforcing members; [0023] [0023]FIG. 9 is a partial perspective view of the fence panel showing the edge of the panel adjacent a post; [0024] [0024]FIG. 10 is a partial perspective view of the C-shaped channel; [0025] [0025]FIG. 11 is a sectional view of a fence panel and a C-shaped member allowing air to pass therebetween; [0026] [0026]FIG. 12 is a partial front view of the C-shaped connector and its spring relationship with the panel edge; [0027] [0027]FIG. 13 is a partial perspective view showing the connection of panels at the center between posts; [0028] [0028]FIG. 14 is a sectional view through two overlapping panels and the contact pads; [0029] [0029]FIG. 15 is a section similar to FIG. 13 but below abutment pads defining an air passage gap; [0030] [0030]FIG. 16 shows an alternate top detail; and [0031] [0031]FIG. 17 is a perspective view of an alternate embodiment; and [0032] [0032]FIG. 18 is a partial front view of an alternate partition panel connected to a post. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0033] The plastic fence section 2 of FIG. 1 includes two fence panels 4 which are interconnected and supported between two spaced posts 6 having blow molded single piece post covers 7 . Each of the fence panels include three horizontal rails per panel and these rails 10 are effectively cavities shaped for receiving a reinforcing member such as a wooden two-by-four. The fence panels are manufactured by blow molding and are of a size of approximately four feet by six feet. Each fence panel 4 is a single piece blow molded plastic component. [0034] The fence section includes six connectors 20 , and eight C-shaped channels 40 for engaging the post edge 120 of each panel, and provides a visual block between the panel and post. [0035] As shown in FIG. 3, the post cover 7 and the underlying four by four wooden post receive and secure the connector 20 . The connector includes an open center port 63 for receiving the two by four reinforcing member extending out of the chamber 10 . The post cover and cap are a single integral piece made by blow molding. The corners of the post cover are U-shaped expansion beads which accommodate tolerance variations common with wooden four by fours. [0036] The C-shaped channel 40 is trapped between the post cover and the panel edge 120 . Edge 120 includes raised pads 122 which have opposed center recesses 124 . C-shaped channel 40 includes inwardly set wedge members 126 which are received in recesses 124 and form an interference fit therewith. This creates a spring bias pushing the C-shaped channel against the post. With thermal expansion of the panel, the panel moves against the spring bias deeper in the channel as shown in FIG. 12. In addition to forming a visual block at the post, the channel also allows wind to flow through the fence as shown in FIG. 11. [0037] A typical section through the fence panel is shown in FIG. 4. As can be seen, the blow molding technique defines a number of chambers 30 with each chamber providing an outer configuration resembling a board. In between the chambers 30 are pinch off areas 32 which are of a double wall thickness and provide vertical stiffening. The individual boards 31 are interrupted by the horizontal reinforcing cavities 10 . These cavities extend across the width of the fence panel and join with like cavities of the adjoining fence panel. [0038] Each fence panel includes a post engaging edge 120 and a panel engaging edge 121 . The panels are reversed such that the panel engaging edge of one panel meets and cooperates with the panel engaging edge of the adjoining panel and collectively form a fence section. The horizontal members interconnect by means of a slip joint generally shown as 16 (see FIGS. 7 and 8). The panel engaging edge 121 includes an offset lap type joint (see FIGS. 14 and 15) which provides visual privacy through the fence but allows for air to move between the lap joints of the two respective panels. The panel edge 16 also includes contact pads 18 at space points along the panel edge 121 to provide abutting contact surfaces between the two fence panels. [0039] Connectors 20 serve to connect the fence panels to the post 6 . These connectors slide over the projecting ends of the horizontal members 10 and the wood reinforcing members 131 . These reinforcing members extend across the length of the plastic fence section between two spaced posts 6 . Basically, the reinforcing members act as horizontal supports and the fence panel section is hung on these reinforcing members. [0040] The lap joint is shown in FIGS. 7 and 8. Basically end 133 overlies inset end 135 . This overlap joint also serves to center the two by four 133 . Each panel can be mechanically fastened by screws on the lower surface of member 10 to the two by four. With this arrangement, expansion movement occurs at the post edge 120 and is accommodated by the C-shaped channels 40 . Any contraction at the slip joint 16 does not reveal the two by four. [0041] [0041]FIG. 7 also shows an overlap plug fit provided at the center joint between two panels. The top rail 200 interfits with the opposed panel to maintain alignment of the rails. The projection 202 has an adjacent recess 204 and projection 206 has an adjacent recess 208 . Half piller 210 abuts and overlaps with half piller 210 of the adjacent panel. [0042] There is a requirement in a plastic fence section to allow for thermal expansion. To accommodate this, the post engaging edge 120 includes a number of raised blocks 122 with centre slots 124 which cooperate with C-shaped members 40 to provide a visual block between the post and the panel edge. The C-shaped members include on the sidewalls, opposed wedge members 126 which are received in the slots 124 of the raised blocks 122 . The raised blocks 122 cooperate with the C-shaped members to provide a spring bias forcing the C-shaped member against the post. The C-shaped members are effectively trapped by the post and the panel, and the legs of the C-shaped member extend over the panel edge. During thermal expansion of the panel, some outward spreading of the C-shaped member, and some inward compression of the raised blocks will occur, and provides a returnable spring bias forcing the C-shaped members 40 against the respective post. In this way, the panel can move relative to the C-shaped member while the C-shaped member continues to provide a spring bias, urging it against the post. This arrangement allows for thermal expansion of the fence panels while continuing to provide a visual block along the length of the fence. The C-shaped channels cannot slide up or down as they are trapped by the horizontal members and are also held in place by recess 124 engaging members 126 . [0043] The horizontal rails 10 include at the post engaging edge, inwardly directed ribs to center the two by four reinforcement member 133 . [0044] [0044]FIG. 5 is a partial sectional view through one of the horizontal members showing the plank extending above and below the horizontal member with the planks being interrupted by the horizontal member 10 . [0045] In contrast, FIG. 6 is a sectional view through one of the pinch offs 32 and in this case, it can be seen how the pinch offs define a double wall thickness as in blow molding, the pinch off is the result of both plastic layers being brought together. [0046] The partial exploded perspective view of FIG. 7 illustrates two spaced fence panels 4 about to be joined with reinforcing members 131 extending out of the horizontal chambers 10 of each panel section. [0047] [0047]FIG. 4 is a partial sectional view showing one fence panel 4 in combination with a length of the C-shaped channel which is also formed as part of the blow molding process and is attached to the fence panel 4 . The blow mold product is cut or trimmed at line A-A leaving the C-shaped channel outwardly facing. The end user cuts the C-shaped channel from the panel along line B-B. The channel is then reversed for securement. Each edge includes four channels. In this way, the produced product includes the C-shaped channel and is shipped to the retailer as a single component. This will reduce stocking problems and will also ensure that each panel section is sold with a C-shaped channel for providing privacy adjacent the post. The shipped product is stackable on a four foot by six foot pallet and therefore, is easily warehoused and shipped through the distribution chain. The panel section is approximately four foot by six foot and is relatively light and easily transported. [0048] [0048]FIG. 3 shows a perspective view of the connector 20 for attachment to a post. The connector includes an open centre port 63 for sliding over the end of a horizontal reinforcing member 131 and this arrangement simplifies the installation of the fence section to the post. Typically, two panels are interconnected by inserting the various horizontal reinforcing members into the panels and then this combined unit is secured by the connectors between two posts (see FIG. 1). The connectors are slipped on the ends of the reinforcing members. The connectors include ports 23 and slots 25 for attaching the connector to a post. The slots are on the lower flanged edge of the connector and the ports 23 are on an upper flanged edge of the connector. The posts can have screws already secured for receipt in the slots 25 of the connector. In this way, the fence section with the two panels, and the reinforcing members, and the connectors, can be assembled on the ground and lifted into place between the posts. The connectors slide onto the previously positioned screws and approximately position the fence section. The fence section can then be adjusted and secured in its final position. [0049] In yet a further alternate design, the top portion of the fence section can continue to have rail 200 , however, a lattice screen is provided between the rail and the uppermost rail 10 and between the uprights 15 of FIG. 1. The lattice could also generally fill this upper area. [0050] The fence panel provides a finished surface to both sides thereof and is considered a good neighbour fence. [0051] [0051]FIG. 16 shows an alternate top detail 215 which can be used. In this case, the planks extend above the upper horizontal member and provides the finished upper detail. This fence panel design is preferrably manufactured using blow mold techniques and the material is preferrably high density polyethylene. The fence panel section of FIG. 1 requires the removal of flashing between the upright members 15 . Flashing can be removed by manual cutting or in an automated manner. The cutting or removal of the flashing is carried out at the time the product is manufactured and is simplified due to the fact the plastic material is still somewhat warm. [0052] [0052]FIG. 17 and FIG. 18 show an alternate system 300 where the C-shaped members provided between a post cover and the partition panel have been removed. [0053] [0053]FIG. 17 shows the alternate system 300 having one fence section 302 defined by the two fence partitions 304 supported between opposed posts. Three two-by-fours 306 are received within the channels of the fence partitions 304 and extend between the opposed posts. Connectors 308 are positioned on the two-by-fours and are then connected to the posts through the post cover and cap 310 . As in the earlier embodiments, the fence partitions are abutted at the center of the fence section and are preferrably mechanically fastened to the two-by-fours by a screw connector such that the two fence partitions are joined at the center of the fence section. The fence sections are of a blow molded plastic and there will be some thermal expansion of these partitions. The partitions are basically free to expand towards the adjacent post. [0054] The embodiment shown in FIG. 17 has very few sku's. The fence system requires the connectors 306 and the fence partition 304 and preferrably, the post cover and cap 310 . The four by fours that are used for the post are already available at lumber stores, and this is also true of the two by fours used as horizontal connectors. [0055] [0055]FIG. 18 shows a gap 330 between the edge of the fence section 304 and the post cover and cap 310 . This gap reduces the visual privacy of the fence system, however, in most cases, this is acceptable. The gap also assists in reducing the wind load that the fence section 302 must withstand. The reduction in the visual privacy is not as substantial as might be initially considered in that the four-by-four post extends either side of the fence partition and thus, the maximum visual gap is when one is directly in front of the gap. The edge of the fence partition 304 is merely a straight bead section centered on the fence section. [0056] Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention of the scope of the appended claims.	A plastic fence section comprises a series of connected hollow chambers with at least upper and lower horizontal chambers extending the length of the fence section for receiving reinforcing members. The fence section is made of plastic material. The hollow chambers are separated by pinch off regions. The fence section provides a visual block and has a similar appearance on either side of the fence section. The fence section has a post edge and a panel joining edge. The panel joining edge is adapted to engage and overlap with a second fence panel section.	4
CROSS-REFERENCE TO RELATED APPLICATION This application is a file wrapper continuation of U.S. patent application Ser. No. 08/355,409, filed Dec. 13, 1994, now abandoned. TECHNICAL FIELD The present invention relates to computer networks and more particularly to the control of access permissions for resources such as files and folders (or directories) in client-server computer networks. BACKGROUND OF THE INVENTION A computer network links together two or more computers by a communication pathway or pathways, allowing the computers to share resources and information. Networks are fast becoming a standard feature of the modern workplace. Local-area networks of personal computers and workstations are practically a necessity in large offices where many individuals must share and exchange computerized information on a daily basis. Wide-area networks connect users and computers at distant locations across the country and around the world. In a network, a server computer is one that provides a resource to a client computer. The same computer can be client in one context and server in another. For example, suppose that computer A has a large hard disk for storing files for an entire office, but lacks its own printer. Elsewhere on the office network, computer B has a printer but no hard disk. If a user of computer B wishes to access a file stored remotely on the disk of computer A, then computer B is the client and computer A is the (file) server. If a user of computer A wishes to print a locally stored file using the printer of computer B, then computer A becomes the client and computer B is the (print) server. A computer that can act as both client and server according to the context is called a peer server. Resource sharing implies issues of resource security. In general, the user of a client computer cannot be trusted with unlimited access to all server resources. Accordingly, the user is required to supply a password in order to log onto the network. Additional mechanisms are used to limit access to particular resources. One such mechanism is a simple share/no-share switch, which can be set either to allow remote access to a given resource from client computers or to restrict remote access so that the resource can be accessed only locally from the server computer. More sophisticated mechanisms used to limit access to particular resources include access control lists, which specify the privileges of particular users with respect to particular resources or collections of resources. Unfortunately, known operating systems for networking personal computers and workstations, such as Microsoft® Windows™ NT by Microsoft Corp. (Redmond, Wash.), employ resource security models that are complex and difficult for users, especially new users, to understand. Compounding the difficulty are highly nonintuitive user interfaces that frustrate users' attempts to understand the security models and to manipulate resource protections within the models, for example, to manipulate user access permissions for file folders or directories stored in a persistent information store such as a hard disk. SUMMARY OF THE INVENTION The system and method of the invention provide a unified and straightforward approach to managing file and other resource security in a networked computing environment. In one aspect, the invention is embodied in a multi-user computer network that includes a client computer, a server computer that controls a resource sharable among users of the network, such as a shared file folder or directory, and a communications pathway between the client computer and the server computer. The resource is organized as a hierarchy of elements with a root element at the top of the hierarchy and additional elements below the root element. According to the invention, a request is received to change a protection, such as an access permission, of an element of the resource hierarchy (other than the root) with respect to a particular network user. If the element in question lacks an associated access control list, a nearest ancestor element of the hierarchy is located that has an associated access control list. The first (descendant) element inherits the access control list of the second (ancestor) element. This inheritance is done by generating a copy of the access control list of the second element and associating the generated copy with the first element. The requested change in protection is then incorporated into the generated copy that has been associated with the first element so as to establish an updated access control list for the first element. Further, the requested change can be propagated downwards in the hierarchy from the first element to its descendants having access control lists. The invention will be better understood with reference to the drawings and detailed description below. In the drawings, like reference numerals indicate like components. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a multi-user network system suitable for providing a shared resource according to the invention; FIG. 2A illustrates the components of a peer server node; FIG. 2B illustrates client and server software components of a peer server node; FIG. 3 illustrates an example of software components of different network nodes; FIG. 4 is an example of a file system hierarchy having folders for which access permissions can be set; FIG. 5 is a high-level flowchart of the steps of setting access permissions for a shareable resource; FIG. 6A is a more detailed flowchart of the steps for receiving from a user interface a command to change resource access permissions; FIG. 6B is an example of a user interface dialog box for changing access permissions for a selected folder of a file system hierarchy; FIG. 7 is a more detailed flowchart of the steps for changing access permissions responsively to a received command; FIG. 8A is a more detailed flowchart of the steps for propagating access permission changes from a folder to its descendants in the file system hierarchy; FIG. 8B is an example of a user interface dialog box for controlling the propagation of access permission changes; and FIG. 9 is a flowchart of the steps for accessing from a client a folder having access permissions. DETAILED DESCRIPTION Overview The invention provides a method and system for establishing or manipulating access controls for particular network resources, such as files and file folders or directories in a hierarchical file storage system associated with a server computer. In a specific embodiment, the invention supports both explicit access controls associated with a node of a file system hierarchy, and implicit access controls inherited from ancestor nodes of the hierarchy and propagated to descendant nodes in the hierarchy. Put differently, if the file system hierarchy is imagined as a tree structure, the invention concerns how changes made to access restrictions at one point in the tree affect and are affected by access restrictions elsewhere in the tree. Further, the invention provides a streamlined user interface that insulates the user from the complexities involved in making these changes. In particular, the invention performs access control inheritance automatically. The user need not be concerned with distinctions between explicit and implicit access controls or the intricacies of the inheritance and propagation logic. Instead, the user perceives a unified, seamless interface. System Components FIG. 1 provides an overview of the system of the invention in a specific embodiment. System 100 includes a network 110 that links multiple computing nodes. Among the nodes of network 110 are peer server 120, which controls persistent storage medium 121; client 130; peer server 140, which controls printer 141; and security provider 190, which acts as an authentication server for the network. Peer server 120, client 130, peer server 140 and security provider 190 all are computers, such as personal computers or workstations. Network 110 can be, for example, a local-area network. Persistent storage medium 121 can include any persistent storage device suitable for reading and writing computer files and organized structures of computer files, such as a magnetic hard disk or writeable optical disk. In the specific embodiment to be described, persistent storage medium 121 is assumed to be a magnetic hard disk, and will hereinafter be referred to as hard disk 121. Printer 141 can be a laser printer, ink-jet printer, or other device for producing hard copy output of computer files. Security provider 190 includes hardware and software used to provide pass-through authentication of users of system 100. In particular, security provider 190 has access to a database of valid users, so that system 100 can screen out users who lack authorization to use the system. Network 110 can include additional computing nodes and support additional file storage, printing, modem, and other resources (not shown). FIG. 1 shows system 100 at the network level. FIGS. 2A-2B provide more detailed views of a node in the network, in particular, of peer server 120. FIG. 2A illustrates the hardware, operating system, and registry of peer server 120. The hardware includes hard disk 121, a processor (CPU) 122, a memory 123, a network interface 124, and hardware for a graphical user interface (GUI) 125, coupled by a local bus or interface 129. Hard disk 121 can be closely coupled to processor 122, for example mounted in the same chassis as processor 122, or can be an external or outboard unit. Network interface 124 connects peer server 120 with network 110. GUI 125 includes a keyboard 126 and a pointing device 127 from which peer server 120 can receive inputs, and a visual display 128 through which peer server 120 can deliver graphical and textual output. Peer server 120 can further include additional hardware and software (not shown). Processor 122 can be, for example, a microprocessor, such as the 80386, 80486 or Pentium™ microprocessor, made by Intel Corp. (Santa Clara, Calif.). Memory 123 can include, for example, random-access memory (RAM), read-only memory (ROM), virtual memory, or any other working storage medium or media accessible by processor 122. GUI 125 facilitates communications between a user and peer server 120, and in particular provides a mechanism for a user to manipulate files and file structures and user access permissions associated therewith. Keyboard 126 is a computer keyboard that includes alphanumeric keys for entering text such as file names and system commands. Pointing device 127 can be, for example, a device such as a mouse, a trackball, a stylus, the user's finger, or any other two- or three-dimensional pointing device. Visual display 128 can include, for example, a cathode-ray tube (CRT) or flat-panel display. Persons of skill in the art will appreciate that a wide range of hardware configurations can support the system and method of the present invention in various specific embodiments. Operating system 150 governs the execution of tasks and the run-time allocation of resources in peer server 120, and includes software which can be loaded from hard disk 121 or other persistent storage into memory 123 and executed by processor 122 as will be understood by those of skill in the art. In the specific embodiment, operating system 150 is the Microsoft® Windows™ 95 operating system f eor IBM PC and compatible computers having or emulating Intel 80386, 80486, or Pentium™ processors. (The invention is also adaptable to other computers and operating systems.) Windows™ 95 supports a hierarchical file system having files and folders. Files can store data, programs, and other computer information, and can be manipulated as objects using the graphical user interface functionality provided by Windows™ 95. Folders, sometimes referred to as "directories," are used to collect related files together and thus provide a convenient way for users to organize their information. Windows™ 95 provides file system security on a per-folder and per-user basis. Access permissions can be determined with respect to a given network user for all files in a given folder. Also, the permissions assigned to the folders at a given point in the file system hierarchy can, but need not, be applied to folders at points lower in the file system hierarchy. Access permissions in Windows™ 95 can include, for example, permissions to read files in a folder, write files in a folder, create files and folders, delete files in a folder, change the attributes of files in a folder (such as the file's read-only flag or the most recent modification date of the file), list the names of files in a folder, and remotely change access permissions of a folder. Access permissions affect remote but not local users. For example, a given user logged into system 100 at peer server 120 can access all the files of peer server 120 stored on hard disk 121, even though the same user lacks permission to access those files remotely from client 130. In particular, the user can always change the access permissions of a folder locally, even though most users (other than system administrators with special access privileges) lack the ability to change permissions remotely. Registry 167 is a configuration database used by operating system 150 to maintain various kinds of system information. In particular, file security component 166 of operating system 150 (see FIG. 2B below) uses registry 167 to store access permissions (access control lists) for resources of peer server 120, such as file folders, that are to be shared with other nodes of network 110. Registry 167 can be stored as shown on hard disk 121. Additionally, portions of registry 167 can be cached in memory 123 for efficient access by processor 122. Because peer server 120 can act variously as either a client or a server, its operating system 150 incorporates server components 151 and client components 152. These software components support the networking capabilities of peer server 120 and more particularly support manipulation, inheritance, and propagation of resource protections according to the invention. FIG. 2B illustrates the client and server software of peer server 120. This software is part of operating system 150. It is used in particular for manipulating user access permissions of folders or directories of files stored on hard disk 121. The individual server components 151 will be described in greater detail momentarily. The individual client components 152 include, in particular, a user interface component 180, which is used in accessing a file or folder on hard disk 121 remotely from another node of network 110. Certain components, in particular components 169 and 170, are considered to be both client and server components because they are used by peer server 120 in both its client and its server capacities. Component 169 is a redirector used in formatting network messages sent and received across network 110. Component 170 supports low-level protocols that processor 122 uses in driving network interface hardware 124 when communicating across network 110. The individual server components 151 will now be described. Component 160 (named MSSHRUI) controls the user interface for establishing and changing access permissions for file folders. Component 161 (CHOOSUSR) controls the aspects of the user interface involved in choosing which users will have access to a folder by adding and removing users from a display list. Component 162 (SVRAPI) is a generic application program interface (API) that is used regardless of the particular networking system being used and the particular protocols and security or permissions model of that system. Component 163 (MSNET32, NWNET32) is an application program interface specific to a particular networking system. For example, the MSNET32 software of component 163 is used in conjunction with Microsoft® Windows™ NT networking, and the NWNET32 software of component 163 is used in conjunction with the NetWare® networking system by Novell, Inc. Provo, Utah). The system-specific application program interface provided by component 163 provides compatibility with pre-existing networks, for example, networks based on Windows™ NT or NetWare® protocols. The generic API of component 162 can automatically select the proper protocol from among the available network protocols supported by component 163. Component 164 (MSAB, NWAB) accesses an address book of users that can be provided to other server components in a format specific to the particular networking system and protocols being used. Component 165 (VSERVER, NWSERVER) is the principal component used to receive and transmit messages across network 110. Component 166 (FILESEC) checks file folder access permissions. Component 168 (MSSP, NWSP) checks user validity by communicating with security provider 190. In particular, component 168 can obtain from security provider 190 a list of user groups (collections of users all of whom are subject to the same access permissions with respect to a particular resource or resources) and store this list locally on hard disk 121. Like components 163 and 164, components 165 and 168, as well as redirector component 169 (VREDIR, NWREDIR), can provide software to support two or more different networking systems and their respective protocols and security models. Registry 167, which was previously described with reference to FIG. 2A, is used by file security component 166 to store access permissions. Because registry 167 is not executable software, it is not, strictly speaking, a part of operating system 150. It is included in FIG. 2B to illustrate its relationship to file security component 166 according to the invention in this embodiment. Other nodes of network 110 of system 100 will now be described. The hardware of client 130 and peer server 140 is similar to the hardware of peer server 120 described with reference to FIG. 2A. However, client 130 differs from peer server 120 in that it can, for example, lack a hard disk analogous to hard disk 121 and lack other shareable resources that would make it suitable for use as a peer server. (Alternatively or additionally, client 130 can be unsuitable for use as a peer server because it has a relatively slow CPU or relatively little memory, or is otherwise unsuitable for managing a significant volume of resource requests from other nodes of network 110.) Client 130 can include a floppy disk drive or other persistent storage device not well-suited for file sharing across a network. Peer server 140 differs from peer server 120 in that it has a printer (specifically, printer 141); it can have a hard disk analogous to hard disk 121 or other persistent storage. The operating system of client 130 is similar to a subset of the operating system 150 of peer server 120 previously described with reference to FIG. 2B. The operating system software of client 130 can be used to control its local resources including, for example, a floppy disk drive. Because client 130 does not act as a server in this embodiment, its operating system software includes client components but need not include server components. The client components of client 130 are analogous to client components 152 of operating system 150 in peer server 120. Client 130 can maintain a registry to store its system information, but because client 130 does not share resources across the network, its registry need not contain access permissions. The software of peer server 140 is similar to the software of peer server 120 described with reference to FIG. 2B. It includes operating system software, analogous to operating system 150, that can be used to control its local and shareable resources including printer 141. Because peer server 140 can act variously as either a client or a server, its operating system software includes both client and server components. These components are analogous, respectively, to server components 151 and client components 152 of peer server 120. Also, peer server 140 maintains in its persistent storage a registry analogous to registry 167 for storing user access permissions for printer 141. FIG. 3 shows an example of software components in use on different nodes of network 110. Peer server 120, which controls hard disk 121, executes server components 151 while client 130 executes client components 152'. Security provider 190 is also shown executing authentication software 191. FIG. 4 provides a concrete example of a file system hierarchy 400 having folders whose access permissions can be set. The folders and files of hierarchy 400 are stored on hard disk 121 in this embodiment. Folder 401 is the root of the hierarchy for device D:\, which is hard disk 121. Folder 401 contains folders including a folder 410 named "Public" and a folder 420 named "Private," and can contain additional files and folders (not shown). Folder 410, in turn, contains folder 411 ("FY '94") and folder 412 ("FY '95") and a file 413 ("Office Party Memo"). Folder 411 contains file 414 ("1994 Q&A") and file 415 ("1994 Review"). Folder 412 contains file 416 ("1995 Q&A") and file 417 ("1995 Outlook"). Folder 420 ("Private") contains folder 421 ("Secret Projects") which contains file 423 ("Project X"), and further contains folder 422 ("Payroll") which contains file 424 ("Pay Spreadsheet Oct '94") and file 425 ("Pay Spreadsheet Nov '94"). Each folder of hierarchy 400 can, but need not, have an associated permissions list called an access control list (ACL). An ACL for a given folder contains a list of users (and user groups) and their respective access permissions for that folder. The folder's ACL is checked each time that any remote user attempts to access the folder or its contents. ACLs are stored in registry 167 and are managed by file security component 166. A folder's access permissions can be inherited by its descendants in hierarchy 400. For example, if folder 420 has an ACL that denies all access permissions to a given user, and folders 421 and 422 lack ACLs of their own, then folders 421 and 422 inherit the permissions of the parent folder 420 and so cannot be accessed by that user. As another example, if folder 401 has an ACL that provides read access for a given user, folder 410 lacks an ACL, folder 411 lacks an ACL, and folder 412 has its own ACL, then folders 410 and 411 inherit the permissions of their ancestor folder 401 with respect to that user, but folder 412 uses its own ACL. Thus the ACL of folder 412 overrides the ACL that would otherwise be inherited from folder 401 in this example. (The root folder 401 has no ancestors and therefore does not inherit in this embodiment.) In this embodiment, inheritance does not proceed beyond the nearest ancestor having an ACL. For example, if folder 411 has no ACL of its own and folders 401 and 410 each have an ACL, folder 411 inherits its ACL from folder 410 but not from folder 401. Thus if the ACL of folder 410 lacks an entry for a particular user, no attempt is made to determine whether that user is listed in the ACL of folder 401 when checking the user's access permissions for folder 411. Similarly, if folder 412 has an ACL and the ACL lacks an entry for a particular user, that user is denied access to folder 412, regardless of the contents of any ACLs that may be associated with ancestor folders 410 and 401. Method Steps FIG. 5 is a high-level flowchart of the steps of setting access permissions of a shareable resource of peer server 120. The shareable resource is stored on hard disk 121 and is part of a resource hierarchy. For concreteness the resource is assumed to be a folder of hierarchy 400, for example folder 410. Commands for manipulating resource access permissions are assumed to be received from user interface 125 of peer server 120. It will be appreciated that the commands could also come from other sources, such as a script file executed by processor 122 or, in some circumstances, from another node of network 110, for example client 130, if the user of the remote node (e.g., a system administrator) has the necessary permissions to change permissions remotely. Initially, the resource for which permissions are to be established or modified is selected (step A). Peer server 120 receives a command to change the permissions for the selected resource (step B). If the command is null, so that there are no changes to be made (step C), the remaining steps of FIG. 5 are skipped. Otherwise, peer server 120 alters the resource access permissions responsively to the received command (step D), propagates changes to the descendants of the resource in the hierarchy (step E), and records the updated permissions in registry 167 (step F). FIG. 6A illustrates step B of FIG. 5 in more detail. Initially, peer server 120 determines whether the selected folder has its own ACL (step AA). If so, the display list that will be presented in user interface 125 and used to set the updated access permissions is simply the folder's ACL (step AB). If not, peer server 120 determines the nearest ancestor having an ACL by searching upwards in the resource hierarchy (step AC) until a folder having an ACL is found or the root of the hierarchy is reached (step AD). If a nearest ancestor having an ACL is found, the display list is the ACL of the ancestor (step AE); otherwise, it is the empty list (step AF). Once the display list is determined, peer server 120 displays in user interface 125 a dialog box that can be used to set permissions for the selected folder (step AG). FIG. 6B illustrates an example of a dialog box 600 suitable for changing the permissions of the folder whose name is "Public," that is, folder 410. Dialog box 600 includes a display list 610 that contains names of user 611 and user groups 612 and 613. A user group identifies a collection of users all of whom are subject to the same access permissions with respect to a particular resource or resources. Associated with each listed user or user group are the access permissions for that user or group. In the example, user 611 ("Annmc") has full access to folder 410. Members of user group 612 ("Chinetui") have limited access to folder 410, with particular access permissions (read, write, create, delete, etc.) specified individually. Members of user group 613 ("The World") have read-only access to folder 410. Dialog box 600 also includes control buttons 615 which, when selected with pointing device 127, cause additional dialog boxes (not shown) to be displayed for use in changing access permissions for the selected resource. Button 616 (labeled "Add") allows a user not in display list 610 to be added to the set of users who can access folder 410. Button 617 ("Remove") allows a user in display list 610 to be removed from the set of users who can access folder 410. Button 618 ("Edit") allows the access permissions for a user in display list 610 to be altered. Dialog box 600 further includes a command button 620 ("OK") that, when selected, issues a command that causes peer server 120 to process all changes made in dialog box 600. According to the invention, the user cannot tell from looking at dialog box 600 whether folder 410 has its own ACL or inherits the ACL of an ancestor. The user sees the same interface either way and is insulated from the details of inheritance, which happens automatically "behind the scenes." Thus the invention provides an easy to-use, intuitive interface for setting access permissions. Returning to FIG. 6A, when the command button 620 is selected, peer server 120 receives a command to process the input from dialog box 600, that is, the changes made to the display list users and their associated permissions with respect to the selected resource. Peer server 120 generates a list of changes (step AI). This is the list of changes that is tested in step C to determine whether anything further needs to be done. Assuming that the list of changes is not empty, processing continues at step D of FIG. 5, whose details are shown in the flowchart of FIG. 7. Processing depends on whether the selected folder already has an ACL of its own or is inheriting from an ancestor, in which case a new ACL will be created for the folder. If the selected folder already has its own ACL (step BA), the changes made to the display list are merged with the previous contents of the ACL to form the updated ACL (step BB). Otherwise, the modified display list itself (minus any users marked as being removed, if these users are still being displayed in dialog box 600) becomes the folder's new ACL. Put another way, in the case where the folder inherits from an ancestor, a copy of the ancestor's ACL is made, the changes to the inherited ACL that were specified in dialog box 600 are applied, and the modified copy becomes the folder's new ACL. Once the selected resource's ACL has been created (if necessary) and updated, the changes made in dialog box 600 can be propagated to its descendants in the resource hierarchy in step E of FIG. 5, whose details are shown in the flowchart of FIG. 8A. Peer server 120 searches the resource hierarchy to determine which descendants of the selected resource, if any, have ACLs of their own (step CA). For example, if the selected resource is folder 410 in hierarchy 400, and if folder 411 has an ACL but folder 412 does not, the search returns folder 411 but not folder 412. If both folders 411 and 412 have ACLs, the search returns both folders 411 and 412. If any descendants having ACLs are found (step CB), the changes made with respect to the selected resource can be propagated to these descendants; otherwise, no propagation is performed and the remaining steps of FIG. 8A are skipped. Because changes are propagated only to those descendant folders already having ACLs, descendant folders whose access permissions have previously been specified as being different from those of the selected folder continue to have different access permissions, while descendant folders whose access permissions are inherited continue to be inherited. If one or more descendants having ACLs were found, peer server 120 displays in user interface 125 a dialog box that can be used to control which of these descendants will be subject to the permissions changes (step CC). FIG. 8B illustrates an example of a dialog box 800 suitable for selecting descendants for propagation of changes. Dialog box 800 include buttons 810, 811, and 812, any one of which can be selected with pointing device 127. Buttons 810, 811, and 812 are used, respectively, to choose all, none, or selected ones of the descendants having ACLs for propagation. If button 812 is selected, an additional dialog box (not shown) can be displayed to permit selection of individual descendant folders. Dialog box 800 further includes a command button 820 that, when selected, issues a command that causes peer server 120 to process the selection made among in dialog box 800. Returning to FIG. 8A, when the command button 620 is selected, peer server 120 receives a command to process the input from dialog box 800. Peer server 120 generates a list of which descendants are subject to propagation of changes (step CE). This can be all the descendants having ACLs, none of them, or a selection of them, according to which of buttons 810, 811, or 812 was selected in dialog box 800. If no descendants in the list (step CF), there is no propagation and the remaining steps of FIG. 8A are skipped. Otherwise, a loop is performed over the descendants in the list (step CG). Peer server propagates to each listed descendant in turn the changes that were made to the selected folder. More particularly, the changes made to the display list of dialog box 600 are merged with the previous contents of each descendant's ACL to form the updated ACL for that descendant. FIG. 9 is a flowchart of the steps for accessing from client 130 a selected folder in a resource hierarchy having associated ACLs. At the outset, a user is assumed to be logged into system 100 from client 130. Responsively to a command issued by the user, client 130 requests peer server 120 to access the folder or a file in the folder (step DA). For example, client 130 can request to open for reading or writing or otherwise access folder 410 or file 415. Peer server 120 receives this request (step DB) and, using components 165 and 168, checks with security provider 190 to authenticate the remote user, that is, to determine whether the user is a valid user of system 100 (step DC). If the user is invalid (step DD), access is denied (step DM). If the user is valid, peer server 120 determines whether the folder has its own ACL (step DE). If so, peer server 120 uses this ACL (step DF); otherwise, peer server 120 searches the resource hierarchy (for example, hierarchy 400) to find the nearest ancestor having an ACL (step DG). If an ancestor is found (step DH), its ACL is inherited (step DI); otherwise, if no ancestor of the folder (including the root of the hierarchy) has an ACL, access is denied (step DM). Peer server 120 performs steps DE through DI using file security component 166, and performs step DM using component 165. Once the appropriate ACL has been determined, peer server 120 uses file security component 166 in conjunction with component 168 to compute the user's permissions for the selected folder in the ACL (step DJ). If the user is not listed by name in the ACL, but the ACL contains one or more group names, a list of user groups previously stored by component 168 can be used to determine the user's group membership; if the user is not among the locally stored groups, a further check can be made with security provider 190 to see whether the user has recently been added to any groups. If the user has permission for the requested access (step DK), access is granted (step DL); otherwise, access is denied (step DM). Peer server 120 can perform step DK using either or both of components 165 and 168, and performs steps DL and DM using component 165. The system and method of the invention are readily adaptable to use in systems, such as system 100, that contain nonhierarchical shareable resources such as printer 141. For nonhierarchical resources, no inheritance or propagation are performed. However, the user interface for setting resource permissions, in particular dialog box 600, remains substantially the same. This is a further advantage of insulating the user from the details of inheritance according to the invention. Further Embodiments Some further illustrative examples of specific embodiments of the invention will now be described. The system and method of the invention are adaptable to different networking systems and their particular protocols and security models, and to hybrid networks that combine different protocols and security models. The invention provides a uniform and consistent user interface regardless of the networking system or systems being used. As another example, the remote administration aspect of the invention wherein resource access permissions stored by the server can be modified remotely from a client node as well as locally at the server, can readily be extended to embodiments in which the permissions list is stored by yet another node of the network. In such embodiments, the user interface for manipulating and administering resource access permissions, the stored permissions themselves, the resource, and the list of users (which is stored by the security provider) can all be on different nodes of the network. Moreover, even the resource and the server can be decoupled, as in the case of a pooled resource such as a distributed collection of printers each capable of producing the same kinds of output and each capable of being driven by any one of a distributed collection of server nodes. Still further, the invention can be used to administer access permissions for many different kinds of resources besides file systems and printers. One such resource is a modem controlled by a dial-up server and used by off-site users to establish access to the network. Another possible resource is the registry of any computer in the network. A system administrator can be given the necessary permissions to provide remote access to the registry of any or all nodes in the system, whereas other users can be denied such access. In this example, even a node that is ordinarily considered a client can act for limited purposes as a server with respect to a resource that it controls, namely the configuration database of its registry. A registry, like a file system, can be a hierarchical resource, so that the inheritance and propagation aspects of the invention come into play in this example. Conclusion The foregoing specific embodiments represent just some of the ways of practicing the present invention. Many others embodiments are possible within the spirit of the invention. Accordingly, the scope of the invention is not limited to the foregoing specification, but instead is given by the appended claims along with their full range of equivalents.	A unified and straightforward approach to managing file and other resource security in a networked computing environment is disclosed. The invention can be implemented in a multi-user computer network that includes a client computer, a server computer that controls a resource sharable among users of the network, such as a shared file folder or directory, and a communications pathway between the client computer and the server computer. The resource is organized as a hierarchy of elements with a root element at the top of the hierarchy and additional elements below the root element. According to the invention, a request is received to change a protection, such as an access permission, of an element of the resource hierarchy (other than the root) with respect to a particular network user. If the element in question lacks an associated access control list, a nearest ancestor element of the hierarchy is located that has an associated access control list. The first (descendant) element inherits the access control list of the second (ancestor) element. This inheritance is done by generating a copy of the access control list of the second element and associating the generated copy with the first element. The requested change in protection is then incorporated into the generated copy that has been associated with the first element so as to establish an updated access control list for the first element. Further, the requested change can be propagated downwards in the hierarchy from the first element to its descendants having access control lists.	8
TECHNICAL FIELD [0001] The present invention relates generally to wall framing assemblies, and more particularly, to header assemblies that support a downwardly directed load above an opening in the framing of a load-bearing wall, as well as to related methods. BACKGROUND OF INVENTION [0002] Metal framing assemblies used to construct commercial and residential buildings are common in the building construction arts. These metal framing assemblies are generally constructed from a plurality of metal framing members including studs, joist, trusses, and other metal posts and beams formed from sheet metal and frequently fabricated to have the same general cross-sectional dimensions as standard wood members used for similar purposes. Metal framing members are typically constructed by roll-forming 12 to 24 gauge galvanized sheet steel. Although many cross-sectional shapes are available, the primary shapes used in residential construction are C-shaped studs and U-shaped tracks. [0003] C-shaped metal studs are typically formed of galvanized sheet-metal bent to encompass a cross-sectional area having nominal dimensions of two inches by four inches. To conform to modern architectural plans and building code requirements, metal studs are formed of sheet-metal bent into a generally C-shaped cross-section in which a relatively broad central base is flanked by a pair of narrower sides that are bent at right angles relative to the base. The central base typically has a uniform nominal width of either four inches or 3⅝ inches and is commonly referred to as the web. The sides of the C-shaped stud typically extend outwardly from the base a nominal distance of two inches and are commonly referred to as flanges. Flanges extending 1¼ or 1½ inches are also common in the trade. To enhance the structural rigidity of the flanges, the ends of flanges are typically bent over into a plane parallel to and spaced apart from the plane of the web. The turned over edges of the flanges define marginal lips that are typically ¼ to ½ inch in width. These lips are also commonly referred to as returns. [0004] In an alternate embodiment of a C-shaped metal stud, instead of lips, a second flange is located along the peripheral edges of the first flange. Like the lips, the second flanges are typically parallel to and spaced apart from the plane of the web. To increase the strength of the studs, the peripheral edges of the second flanges may be bent inwardly to form a pair of confronting lips (or returns) that are parallel to the first flanges. Studs including this C-shaped configuration can be purchased under the trade name HDS Framing Systems manufactured by Dietrich Metal Framing. HDS studs with 3⅝ inches wide webs typically have a pair of second flanges that are 1 1/16 inches wide and a pair of lips that are ¾ inches wide. HDS jamb members are also commercially available with a web that is 6 inches, a pair of first flanges that are 3 inches, a pair of second flanges that are 2¼ inches, and a pair of lips that are ¾ inches wide. [0005] U-shaped tracks generally include a planar web section flanked along both longitudinally extending edges by a perpendicular flange or sidewall. The sidewalls confront each other and extend approximately the same distance from the web. U-shaped tracks perform many framing functions and are available in many standard sizes. In many applications, C-shaped studs or other framing members are received between the sidewalls and within the opening of a U-shaped track. [0006] Steel framing can be used to build wall sections in a manner similar to that employed in conventional wooden wall framing. Steel framed wall sections are typically formed from a U-shaped top and a U-shaped bottom runner (also referred to as an upper and lower track) with a plurality of spaced apart C-shaped studs arranged at predetermined intervals between the top and bottom runners. For example, it is common practice to vertically position wall studs at 16 inch from center intervals. [0007] Many architectural building plans include wall configurations, fixtures, and other architectural elements that interfere with the wall studs preventing them from traversing the full distance between the top and bottom runners. For example, at the location of openings in a load-bearing wall such as doors, windows, fireplaces, and the like, the studs, which are generally placed closer together than the width of the opening, interfere with the opening. Further, other aspects of building construction such as heating ducts, plumbing fixtures and piping, electrical components, and the like conflict with the framing studs and sometimes prevent the studs from traversing the full distance between the top and bottom runners. [0008] If for some reason the studs are prevented from extending the full distance between the top and bottom runners, a header assembly must be installed to bear the load that would have been born by the studs. A typical header assembly includes a pair of spaced apart vertical jamb members defining an opening therebetween and at least one horizontal header member bridging the opening between the vertical jamb members. Generally, the jamb members are positioned so that their webs confront each other along opposite sides of the opening defined between the jamb members. The header member receives the load above the opening and transfers a portion of that load to the vertical jamb members. If the top of the opening is directly below the top runner, the header assembly may abut the underside of the top runner. Otherwise, one or more shortened studs (often referred to as cripple or kicker studs) span the distance between the top runner and the top surface of the header assembly. Typically, the kicker studs are located at the same center spacing as the other wall framing studs. [0009] For many applications, specially constructed jamb members are required. Jamb members are typically capable of supporting a larger load than a wall stud and for this reason, may be constructed from a heavier gauge sheet metal or have a larger cross-sectional area than a wall stud. While jamb members can be distinguished from wall studs, jamb members may be constructed with C-shaped cross-sections and cross-sectional areas similar to those of wall studs. [0010] The construction of a header assembly requires either the purchase of a specialized header member (and/or related clips) or the costly and inefficient modification of standard framing members such as studs. Specialized header members specially constructed to couple with jamb members are common in the trade. Many of these specialized header members are configured to interface with one or more clips or other coupling assemblies that couple the header member to the jamb members. For example, the ProX header manufactured by Brady Construction Innovations, Inc. includes a generally W-shaped header member (and optionally an M-shaped insert) that is attached at both ends to the jamb members by clips mounted to the jamb members. ProX headers are available in 2½, 3⅝, 4, 6, and 8 inch widths and 40, 60, and 80 inch lengths. Similarly, the following patents disclose header assemblies that use specialized header members and/or clips in their construction: U.S. Pat. No. 5,802,782 to Jewell (discloses an assembly for performing a header connection that includes a header member with a pair of longitudinally projecting flanges disposed on each end which are fastened to a corresponding set of flanges disposed on the jamb members), and U.S. Pat. No. 5,689,922 to Daudet (discloses a metal structural framing for building construction, including a one-piece jamb member and a one-piece load-bearing header member connected to the jamb member). [0011] Many header assemblies including the costly and inefficient modification of standard framing members such as studs can be found in the prior art. For example, one method of constructing a header assembly from two standard C-shaped framing members, such as studs, involves removing a portion of the flanges and lips attached thereto from the ends of two framing members. The portion removed extends from each end of the framing member for a distance less than or approximately equal to the width of the sides of the jamb members formed by the outside surface of the flanges perpendicular to the web. In this manner, only a section of the web projects from both ends of the C-shaped framing members. The projecting web sections located at the ends of the C-shaped framing members are bent outwardly slightly away from the flanges. Then, the header members are mounted one at a time to the pair of spaced apart jamb members by placing the projecting web sections flush against the sides of the jamb members and attaching the projecting web sections thereto with a plurality of fasteners such as screws. Typically, the header members are mounted at approximately the same height along opposite sides of the jamb members. In this manner, two header members may span one pair of jamb members in a substantially parallel and horizontal load-bearing arrangement. [0012] This method has several drawbacks. First, mounting the web of the C-shaped member to the sides of the jamb members creates an undesirable mound of metal and/or fasteners that extends above the planar surface of the side of the jamb members and may be difficult to disguise within the finished wall. Second, the load transferred to the header members is transferred first to the fasteners, such as screws, bolts, or rivets, connecting the header members to the jamb members before the load is transferred to the jamb members. Therefore, the load-bearing capacity of the header assembly is dependent upon the type and quantity of fasteners used. Finally, this method requires the modification of standard building materials at the work site and renders the construction of each header assembly a time consuming and costly custom framing project. [0013] One method of reducing the labor involved in constructing a header assembly using header members constructed from two standard C-shaped framing members, such as studs, is to use clips to attach the header members to the jamb members. For example, Curtain Wall manufactures a clip under the trademark STIFFCLIP® that removes the need to modify the header members. These clips include a substantially planar plate and a single bottom flange perpendicular to and formed along a portion of the bottom edge of the plate. The plate of the clip is positioned immediately adjacent to both the web of one of the header members and the side of one of the jamb members and spans the gap between the header member and the jamb member. The plate includes a plurality of pre-punched holes into which a plurality of fasteners such as screws are received. The underside of the header member abuts and is cradled by the bottom flange of the clip for additional support. Because one clip attaches the web of only one of the header members to the side of one of the jamb members, a total of four clips are required to construct a single header assembly. Dietrich Metal Framing manufactures a similar clip, also referred to as a hanger, under the trade name H-Series Universal Header Hanger. While clips such as those described above may reduce the time required to construct the header assembly, they do not address the other drawbacks of the previously described method. [0014] Therefore, a need exists for header assemblies that incorporate standard metal framing components. A need also exists for header assembly designs that do not depend upon the quality and quantity of fasteners used to attach the header member(s) to the jamb members to achieve the desired load-bearing capability. Further, a need exists for header assemblies that can be assembled and installed more efficiently. A need also exists for header assemblies that avoid the creation of an undesirable mound of metal and/or fasteners at the intersection of the header members and jamb members that must be disguised within the finished wall. The present invention fulfills these needs and provides for further related advantages. SUMMARY OF THE INVENTION [0015] In one embodiment, the present invention is directed to a load-bearing framing assembly that comprises: a pair of horizontally positioned header members for receiving a downwardly directed load, each header member being spaced apart and parallel to the other, each header member having first and second end sections; a pair of parallel and vertically positioned sheet-metal jamb members, each jamb member being spaced apart and confronting the other so as to define an opening, each jamb member being c-shaped and having an inwardly facing planar web flanked along its opposing vertical edges by confronting and outwardly directed flanges, with each flange being perpendicular to the web and having outer lips parallel to the web and confronting each other, each web having first and second apertures positioned a selected distance away from the bottom of the opening and spaced apart from each other, thereby defining a spacer section of the web, each of the first and second apertures being sized and configured to receive in an operative arrangement the respective first and second end sections of the pair of header members; and wherein the load-bearing framing assembly is characterized in that the respective first and second end sections of the pair of header members are received into the first and second apertures of each web of the pair of jamb members such that the outer lips of each flange abut or nearly abut the respective first and second end sections of the pair of header members. [0016] In another embodiment, the present invention is directed to a method for making a load-bearing wall assembly, wherein the method comprises at least the following steps: providing and positioning onto a floor and a ceiling respective bottom and top tracks such that the top and bottom tracks are spaced apart and confronting each other; providing and vertically positioning within the top and bottom tracks a pair of jamb members such that each jamb member is spaced apart and confronting the other so as to define an opening, each jamb member being C-shaped or U-shaped and having an inwardly facing planar web flanked along its opposing vertical edges by confronting and outwardly directed flanges, with each flange being perpendicular to the web and having outer lips parallel to the web and confronting each other, each web having first and second apertures positioned a selected distance away from the bottom of the opening and spaced apart from each other, thereby defining a spacer section of the web, each of the first and second apertures being sized and configured to receive in an operative arrangement respective first and second end sections of a pair of header members; and providing and horizontally positioning the first and second end sections of the pair of header members within the first and second apertures such that each header member is spaced apart and parallel to the other and such that the outer lips of each flange abut or nearly abut the respective first and second end sections of the pair of header members. [0017] These and other aspects of the present invention will become more evident upon reference to the following detailed description and attached drawings. It is to be understood, however, that various changes, alterations, and substitutions may be made to the specific embodiments disclosed herein without departing from their essential spirit and scope. Finally, it is expressly provided that all of the various references cited herein are incorporated herein by reference in their entireties for all purposes. BRIEF DESCRIPTION OF THE DRAWINGS [0018] The drawings are intended to be illustrative and symbolic representations of certain exemplary embodiments of the present invention and as such they are not necessarily drawn to scale. In addition, and for purposes of clarity, like reference numerals have been used to designate like features throughout the several views of the drawings. [0019] FIG. 1 illustrates a side perspective view of a load-bearing framing assembly adapted for use as a header assembly for supporting the load above an opening in the framing of a wall. [0020] FIG. 2 illustrates a partial side perspective sectional view of one embodiment of the load-bearing framing assembly illustrated in FIG. 1 with one of the header members removed to better illustrate aspects of the invention taken at the sectioning plane and in the direction indicated by line a-a defined in FIG. 1 . [0021] FIG. 3 illustrates a partial side perspective view of one embodiment of a jamb member of the load-bearing framing assembly of FIG. 1 . [0022] FIG. 4 illustrates a partial side perspective view of a first alternate embodiment of a jamb member of the load-bearing framing assembly of FIG. 1 . [0023] FIG. 5 illustrates a partial side perspective sectional view of a second alternate embodiment of a jamb member of the load-bearing framing assembly of FIG. 1 . [0024] FIG. 6 illustrates a side view of the load-bearing frame assembly of FIG. 1 installed within an exemplary wall framing assembly that includes a top runner, bottom runner, and studs extending vertically between the top runner and bottom runner. [0025] FIG. 7 illustrates a partial side perspective sectional view of one embodiment of the header members of the load-bearing framing assembly installed within the exemplary wall illustrated in FIG. 6 taken at the sectioning plane and in the direction indicated by line b-b defined in FIG. 6 . [0026] FIG. 8 illustrates a side view of an alternate embodiment of the load-bearing frame assembly incorporating the jamb member of FIG. 5 wherein the top surfaces of the header members of the load-bearing frame assembly abut the inside surface of the web of the top runner of the exemplary wall framing assembly. DETAILED DESCRIPTION OF THE INVENTION [0027] Referring now to the drawings wherein like reference numerals designate identical or corresponding elements, and more particularly to FIGS. 1 , 6 , and 8 , the present invention is directed to a load-bearing framing assembly 10 adapted for use as a header assembly for supporting the load above an opening in the framing of a wall. Load-bearing framing assembly 10 includes a pair of substantially parallel horizontal spaced apart header members 100 a and 100 b . Each of the header members 100 a and 100 b includes a first end 140 a and 140 b , respectively, and second end 160 a and 160 b , respectively. [0028] Load-bearing framing assembly 10 also includes a pair of spaced apart vertical jamb members 200 a and 200 b , each with a C-shaped cross-section 202 a and 202 b , respectively. The spaced apart jamb members 200 a and 200 b define an opening 300 therebetween with bottom 302 . As appreciated by those of ordinary skill in the art, the vertical jamb members 200 a and 200 b may be disposed within a U-shaped bottom track or bottom runner 400 . In this manner, the bottom 302 of the opening 300 occurs along the inside surface 404 of the web 402 of the bottom runner 400 . [0029] Each of the vertical jamb members 200 a and 200 b includes a pair of apertures 240 and 242 (best seen in FIGS. 2 and 3 ) located a distance d from the bottom 302 of the opening 300 . The first end sections 140 a and 140 b of the header members 100 a and 100 b are received into the apertures 240 and 242 of the first jamb member 200 a . Similarly, the second end sections 160 a and 160 b of the header members 100 a and 100 b are received into the apertures 240 and 242 of the second jamb member 200 b . In this manner, the top of opening 300 is defined by the underside of header members 100 a and 100 b . Fasteners 280 may be used to affix the ends of the header members 100 a and 100 b to the vertical jamb members 200 a and 200 b. [0030] Referring to FIG. 2 , the structure of the header members 100 a and 100 b will be discussed in detail. FIG. 2 is a sectional view of one embodiment of the present invention illustrated in FIG. 1 taken at the sectioning plane and in the direction indicated by line a-a defined in FIG. 1 . Header member 100 a has been removed from FIG. 2 to provide a better view of aspects of the invention. While the structure of the header members 100 a and 100 b will be discussed with reference to header member 100 b , it is understood by those of ordinary skill in the art that header member 100 a includes structural components identical or substantially similar to those of header member 100 b. [0031] Header members 100 a and 100 b may include a generally C-shaped cross-section 102 . The C-shaped cross-section 102 may include a planar web 104 flanked along its opposing horizontal edges 106 and 108 by flanges 110 and 112 , respectively. Flanges 110 and 112 extend perpendicularly from the web 104 in substantially the same direction and for substantially the same distance from the web 104 . Optionally, flanges 110 and 112 may be bent along edges 114 and 116 to form a pair of lips 118 and 120 that are perpendicular to the flange from which they extend. The lips 118 and 120 are generally parallel to the web 104 and extend from edges 114 and 116 toward each other. In one embodiment, header members 100 a and 100 b are constructed from a section of a standard C-shaped metal stud. [0032] Referring to FIG. 3 , one embodiment of the structure of the jamb members 200 a and 200 b will be discussed in detail. Typically, jamb members 200 a and 200 b will be constructed and configured to exhibit substantially identical structural features. One embodiment of jamb member 200 b suitable for use with the present invention can be best viewed in FIG. 3 . Jamb member 200 b may include a C-shaped cross-section 202 b . C-shaped cross-section 202 b may include a planar web 204 flanked along its opposing horizontal edges 206 and 208 by flanges 210 and 212 , respectively. For typical residential constructions, the width of the web 204 between the flanges 210 and 212 may be about 3½ or 5½ inches, and for ordinary commercial/industrial constructions about 3⅝, 6, 8, or 10 inches. However, as is appreciated by those of ordinary skill in the art, the width of the web 204 may be increased or decreased as desired for customized installations. Flanges 210 and 212 extend perpendicularly from the web 204 in substantially the same direction and for substantially the same distance from the web 204 . Typically, the flanges 210 and 212 extend about 1⅜, 1⅝, 2, or 2½ inches from the web 204 . Optionally, flanges 210 and 212 may be bent along edges 214 and 216 to form a pair of confronting lips 218 and 220 that are substantially parallel to the web 204 and extend from edges 214 and 216 toward each other. Each lip 218 and 220 extends about ⅜ to ⅝ inches. [0033] Web 204 includes two apertures 240 and 242 located distance d from the bottom 302 of the opening 300 . Referring to FIG. 2 , the header members 100 a and 100 b may include a C-shaped cross-section 102 that resides within a predetermined spatial envelope. The shape and size of apertures 240 and 242 are configured to accommodate the spatial envelope occupied by the C-shaped cross-section 102 of the header members 100 a and 100 b . In this manner, each of the apertures 240 and 242 may be suitably shaped and sized to receive one end section 140 a , 140 b , 160 a , or 160 b of header member 100 a or 100 b . Apertures 240 and 242 may be formed using any suitable method known in the art for forming apertures in the sheet metal of metal framing members. [0034] In one embodiment, the vertical height of the apertures 240 and 242 is larger than the vertical height of the C-shaped cross-section 102 of the header member 100 a or 100 b received therein allowing vertical movement of the header member 100 a or 100 b within the aperture 240 or 242 . In this manner, the header members 100 a and 100 b can be positioned vertically to achieve a square and plumb load-bearing framing assembly 10 . Additionally, the width of the apertures 240 and 242 may be larger than the width of the C-shaped cross-section 102 of header member 100 a or 100 b allowing lateral movement of the header member 100 a or 100 b within aperture 240 or 242 . In this manner, the header members 100 a and 100 b can be rotated within the apertures 240 and 242 and/or positioned laterally to achieve a square and plumb load-bearing framing assembly 10 . As will be appreciated by one of ordinary skill in the art, spacers and shims (not shown) may be used to limit or prevent movement of the header members 100 a and 100 b within the apertures 240 and 242 . [0035] Apertures 240 and 242 define a spacer section 260 therebetween. Spacer section 260 determines the lateral spacing of the horizontal header members 100 a and 100 b . In embodiments including C-shaped jamb members 200 a and 200 b each including a longitudinal opening occurring opposite the web 204 , the spacer section 260 may act as a guide that directs the end sections 140 a , 140 b , 160 a , and 160 b of the header members 100 a and 100 b into lips 118 and 120 . In this manner, the end sections 140 a , 140 b , 160 a , and 160 b of the header members 100 a and 100 b abut the lips 118 and 120 of each jamb member 200 a and 200 b instead of passing through the longitudinal opening in the jamb member 200 a and 200 b . The spacer section 260 may also limit the lateral movement of the header members 100 a and 100 b and provide opposition to inwardly directed lateral forces. In particular, the spacer section 260 may limit the lateral movement of the header members 100 a and 100 b during the attachment of fasteners 280 that provide an inwardly directed lateral force on the portion of the web 104 occurring along the first end sections 140 a and 140 b and second end sections 160 a and 160 b. [0036] Referring to FIG. 4 , the structure of jamb member 500 , an alternate embodiment of the C-shaped cross-section structure of the jamb members 200 a and 200 b , will be described. The two least significant digits of the reference numbers of jamb member 200 b and jamb member 500 identify identical or corresponding structures of the two embodiments. For this reason, only the structures of jamb member 500 that differ from those of jamb members 200 b and structures related thereto will be described. [0037] Jamb member 500 includes a C-shaped cross-section 502 including a planar web 504 flanked along its opposing horizontal edges 506 and 508 by flanges 510 and 512 , respectively. Flanges 510 and 512 extend perpendicularly from the web 504 in substantially the same direction and for substantially the same distance from the web 504 . The flanges 510 and 512 may be bent along edges 514 and 516 to form a second pair of flanges 519 and 521 that extend from edges 514 and 516 toward each other for a predetermined distance. The second pair of flanges 519 and 521 may be bent along edges 523 and 525 to form a pair of lips 527 and 529 . In this embodiment, the lips 527 and 529 extend from edges 523 and 525 toward the web 504 . As will be appreciated by one of ordinary skill in the art, while the cross-sectional shape of jamb member 500 varies from the cross-sectional shape of jamb member 200 b , apertures 540 and 542 may be shaped, sized, located, and constructed in the same manner as apertures 240 and 242 of jamb member 200 b. [0038] Referring to FIG. 5 , the structure of jamb member 600 , an alternate embodiment of the structure of the jamb members 200 a and 200 b , will be described. The two least significant digits of the reference numbers of jamb member 200 b and jamb member 600 identify identical or corresponding structures of the two embodiments. For this reason, only the structures of jamb member 600 that differ from those of jamb members 200 b and structures related thereto will be described. Jamb member 600 is adapted to form a load-bearing framing assembly 10 ′ that abuts the top runner 420 (please refer to FIG. 8 to view one embodiment of such a configuration). Jamb member 600 differs from jamb member 200 b only with respect to apertures 640 and 642 . Specifically, unlike apertures 240 and 242 which are completely defined by the web 204 , apertures 640 and 642 are open along the top edge. In this manner, the top surfaces of header members 100 a and 100 b formed by the outside surfaces of the flanges 112 may abut the inside surface 424 ( FIG. 7 ) of the top runner 420 . While the C-shaped cross-section 602 of jamb member 600 has been described as generally consistent with that of the embodiment described with reference to FIG. 3 , it is appreciated by those of ordinary skill that alternate and equivalent C-shaped cross-sectional shapes including the cross-sectional shape described with reference to FIG. 4 may be used to construct jamb member 600 . [0039] Referring to FIGS. 6 and 7 , load-bearing framing assembly 10 may include an optional U-shaped top track 700 disposed upon and affixed to the top surfaces formed by the outside surfaces of flanges 112 of the header members 100 a and 100 b . Top track 700 may include a horizontal web 702 flanked by two vertical flanges or sidewalls 704 and 706 . In one embodiment, the outside surface of the horizontal web 702 of the top track 700 is attached to the top surfaces of the header members 100 a and 100 b with the vertical sidewalls 704 and 706 extending upwardly. The top track 700 may be affixed to the header members 100 a and 100 b by fasteners 708 such as screws extending from the inside surface of the horizontal web 702 of the top track 700 through the flanges 112 of the header member 100 a and 100 b . Kicker studs 910 may be affixed to the top track 700 between the sidewalls 704 and 706 by any method known in the art for effecting such an attachment including but not limited to fastening the flanges of the kicker studs 910 to the sidewalls 704 and 706 of the top track 700 with fasteners 710 and fastening the web 912 of the kicker studs 910 to the top track 700 with clips (not shown). [0040] Load-bearing framing assembly 10 may include an optional U-shaped bottom track 720 . Bottom track 720 may include a horizontal web 722 flanked by two vertical flanges or sidewalls 724 and 726 . The inside surface of the web 722 of the bottom track 720 may be positioned adjacent to the bottom surfaces formed by the outside surfaces of flanges 110 of the header members 100 a and 100 b . In one embodiment, the inside surface of the horizontal web 722 of the bottom track 720 is attached to the header members 100 a and 100 b with the vertical sidewalls 724 and 726 of the bottom track 720 extending upwardly. In this configuration, the bottom track 720 cradles the bottom surfaces of the header members 100 a and 100 b , sandwiching the header members 100 a and 100 b between the vertical sidewalls 724 and 726 of the bottom track 720 . The positioning of the bottom track 720 along the bottom surfaces of the header members 100 a and 100 b may be adjusted to achieve a square and plumb opening 300 . The bottom track 720 may be affixed to the header members 100 a and 100 b by any method known in the art including fastening the sidewalls 724 and 726 of the bottom track 720 to the webs 104 of the header members 100 a and 100 b with fasteners 730 such as screws. [0041] Insulation 180 may be installed in the cavities of the C-shaped header members 100 a and 100 b and into the longitudinal separation between the parallel horizontal header members 100 a and 100 b . In one embodiment, insulation 180 includes a generally rectilinear insulating element 182 configured for insertion into the ends of the header members 100 a and 100 b . Rectilinear insulating element 182 may include a pair of parallel longitudinal channels or grooves 184 located along both its top and bottom surfaces for receiving the lips 118 and 120 of each header member 100 a and 100 b . Alternatively, insulation 180 may include loose insulating material capable of being packed into the cavities of and longitudinal separation between the C-shaped header members 100 a and 100 b . Insulation 180 may be constructed from any suitable insulating material including Styrofoam, fiberglass, glass wool, and the like. [0042] With reference to FIGS. 1 , 6 , and 7 , a method of constructing an embodiment of load-bearing framing assembly 10 of the present invention will now be described. FIG. 6 depicts a load-bearing framing assembly 10 constructed in accordance with the present invention installed within an exemplary wall framing assembly 900 . Exemplary wall framing assembly 900 includes top runner 420 , bottom runner 400 , and studs 902 extending vertically between the top runner 420 and bottom runner 400 . Load-bearing framing assembly 10 may be constructed by affixing the top end of first vertical jamb member 200 a to the top runner 420 and the bottom end of the first jamb member 200 a to the bottom runner 400 . In this manner, the first jamb member 200 a traverses the vertical distance between the top and bottom runners 420 and 400 and supports a portion of the downwardly directed load applied to the top runner 420 . The first jamb member 200 a may be affixed to the top and bottom runners 420 and 400 by any method known in the art including but not limited to fastening the flanges 210 and 212 of the first jamb member 200 a to the sidewalls 426 and 428 of the top runner 420 and the sidewalls 406 and 408 of the bottom runner 400 . Alternatively, the first jamb member 200 a may be affixed to the top and bottom runners 420 and 400 by fastening the web 204 of the first jamb member 200 a to the top and bottom runners 420 and 400 with clips (not shown). [0043] The first end sections 140 a and 140 b of the header members 100 a and 100 b are inserted into the apertures 240 and 242 of the first jamb member 200 a until the first end sections 140 a and 140 b abut the lips 218 and 220 of the first jamb member 200 a . Alternatively, in embodiments where jamb member 200 a is constructed with the C-shaped profile consistent with that of jamb member 500 , the first end sections 140 a and 140 b are inserted until they abut the lips 527 and 529 . Optionally, insulation 180 may be inserted into the cavities of the C-shaped header members 100 a and 100 b and into the longitudinal separation between the parallel horizontal header members 100 a and 100 b . With respect to embodiments of insulation 180 including a rectilinear insulating element 182 , rectilinear insulating element 182 may be inserted into the end of end sections 160 a and 160 b passing through the cavities of the C-shaped header members 100 a and 100 b and/or longitudinal separation between the parallel horizontal header members 100 a and 100 b until the inserted end of rectilinear insulating element 182 abuts the web 204 of jamb member 200 a. [0044] Next, the second end sections 160 a and 160 b of the header members 100 a and 100 b are inserted into the apertures 240 and 242 of the second jamb member 200 b until the second end sections 160 a and 160 b abut the lips 218 and 220 of the second jamb member 200 b . Alternatively, in embodiments where jamb member 200 a is constructed with the C-shaped profile consistent with that of jamb member 500 , the first end sections 140 a and 140 b are inserted until they abut the lips 527 and 529 . Then, the second vertical jamb member 200 b is affixed to the top and bottom runner 420 and 400 using any of the methods suitable for affixing the first jamb member 200 a therebetween. The portions of the web 104 of the first end sections 140 a and 140 b and second end sections 160 a and 160 b of the header members 100 a and 100 b adjacent to the flanges 210 and 212 of the jamb members 200 a and 200 b may be affixed thereto with fasteners 280 that extend inwardly through the flanges 210 and 212 of the jamb members 200 a and 200 b into the portion of the web 104 of the header members 100 a and 100 b adjacent thereto. [0045] Optional U-shaped top track 700 may be installed along to the top surfaces of the header members 100 a and 100 b by inserting fasteners 708 such as screws into the inside surface of the horizontal web 702 of the top track 700 through the flanges 112 of the header member 100 a and 100 b . A portion of the load applied to the top runner 420 may be transferred to the header members 100 a and 100 b by installing kicker studs 910 between the top runner 420 and top track 700 . As described above, the kicker studs 910 may be affixed to the top track 700 between the sidewalls 704 and 706 by any method known in the art for effecting such an attachment. Optional bottom track 720 may be installed along the bottom surfaces of the header members 100 a and 100 b by inserting fasteners 730 such as screws into the sidewalls 724 and 726 of the bottom track 720 and into the webs 104 of the header members 100 a and 100 b . The attachment of optional bottom track 720 to header members 100 a and 100 b may be adjusted to achieve a square and plumb opening 300 . [0046] With reference to FIGS. 5 and 8 , a method of constructing an alternate embodiment of load-bearing framing assembly 10 of the present invention will now be described. FIG. 8 depicts load-bearing framing assembly 10 ′ constructed in accordance with the present invention installed within a second exemplary wall framing assembly 900 ′. Second exemplary wall framing assembly 900 ′ includes top runner 420 , bottom runner 400 , and studs 902 extending vertically between the top runner 420 and bottom runner 400 . In this embodiment, first vertical jamb member 600 a , constructed in accordance with jamb member 600 depicted in FIG. 5 , is affixed to the bottom runner 400 in the same manner that first vertical jamb member 200 a of the previous embodiment was similarly affixed. [0047] The open edges of the apertures 640 and 642 are disposed within the U-shaped top runner 420 and are immediately adjacent to the inside surface 424 of the web 422 of the top runner 420 . The first end sections 140 a and 140 b of the header members 100 a and 100 b are inserted into the apertures 640 and 642 of the first jamb member 600 a until the first end sections 140 a and 140 b abut the lips 618 and 620 of the first jamb member 600 a . The top surface of the header members 100 a and 100 b formed by the outer surfaces of flanges 112 is positioned against the inside surface 424 of the web 422 of the top runner 420 . In this manner, a portion of the downwardly directed load applied to the top runner 420 may be transferred to the header members 100 a and 100 b . As described above, optional insulation 180 may be inserted into the cavities of the C-shaped header members 100 a and 100 b and into the longitudinal separation between the parallel horizontal header members 100 a and 100 b. [0048] Next, the second end sections 160 a and 160 b of the header members 100 a and 100 b are inserted into the apertures 640 and 642 of the second jamb member 600 b until the second end sections 160 a and 160 b abut the lips 618 and 620 of the second jamb member 600 b . The portions of the web 104 of the first end sections 140 a and 140 b and second end sections 160 a and 160 b of the header members 100 a and 100 b adjacent to the flanges 610 and 612 of the jamb members 200 a and 200 b may be affixed thereto with fasteners 280 that extend inwardly through the flanges 610 and 612 of the jamb members 600 a and 600 b into the portion of the web 104 of the header members 100 a and 100 b adjacent thereto. Similarly, fasteners 280 may be used to attach the jamb members 600 a and 600 b to the top runner 420 . In this configuration, fasteners 280 extend inwardly through three layers metal including one of the sidewalls 426 or 428 of the top runner 420 , one of the flanges 610 or 612 of jamb member 600 a or 600 b , and portion of the web 104 of header member 100 a or 100 b . The web 104 of the header members 100 a and 100 b may be fastened to the sidewall 426 or 428 of the top runner 420 with fasteners 430 . An optional bottom track 720 of the same type described with reference to FIG. 6 may be positioned along the bottom surfaces formed by the outside surfaces of flanges 110 and attached to the header members 100 a and 100 b. [0049] While the present invention has been described in the context of the embodiments illustrated and described herein, the invention may be embodied in other specific ways or in other specific forms without departing from its spirit or essential characteristics. Therefore, the described embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing descriptions, and all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.	The present invention relates to header assemblies that support a downwardly directed load above an opening in the framing of a load-bearing wall, as well as to related methods. In one embodiment, a load-bearing framing assembly is disclosed. The load-bearing header assembly comprises: a pair of horizontally positioned header members for receiving a downwardly directed load; and a pair of parallel and vertically positioned sheet-metal jamb members. The header members are disposed within the jamb members. In another embodiment, a method for making a load-bearing wall assembly is disclosed. The method comprises at least the following steps: providing and positioning onto a floor and a ceiling respective bottom and top tracks; providing and vertically positioning within the top and bottom tracks a pair of jamb members; and providing and horizontally positioning within the pair of jamb members a pair of header members.	4
TECHNICAL FIELD This invention relates generally to transdermal drug delivery, and more particularly relates to methods and drug delivery systems for administering olanzapine transdermally. The invention additionally relates to pharmaceutical compositions formulated for transdermal administration of olanzapine. BACKGROUND The delivery of drugs through the skin provides many advantages; primarily, such a means of delivery is a comfortable, convenient and noninvasive way of administering drugs. The variable rates of absorption and metabolism encountered in oral treatment are avoided, and other inherent inconveniences--e.g., gastro-intestinal irritation and the like--are eliminated as well. Transdermal drug delivery also makes possible a high degree of control over blood concentrations of any particular drug. Skin is a structurally complex, relatively thick membrane. Molecules moving from the environment into and through intact skin must first penetrate the stratum corneum. They must then penetrate the viable epidermis, the papillary dermis, and the capillary walls into the blood stream or lymph channels. To be so absorbed, molecules must overcome a different resistance to penetration in each type of tissue. Transport across the skin membrane is thus a complex phenomenon. However, it is the cells of the stratum corneum which present the primary barrier to absorption of topical compositions or transdermally administered drugs. The stratum corneum is a thin layer of dense, highly keratinized cells approximately 10-15 microns thick over most of the body. It is believed to be the high degree of keratinization within these cells as well as their dense packing which creates in most cases a substantially impermeable barrier to drug penetration. Relatively recent advances in transdermal drug delivery have enabled effective administration of a variety of drugs through the skin. These advances include the development of a number of skin penetration enhancing agents, or "permeation enhancers," to increase skin permeability, as well as non-chemical modes for facilitating transdermal delivery, e.g., the use of iontophoresis, electroporation or ultrasound. Nevertheless, the number of drugs that can be safely and effectively administered through the skin, without concomitant problems such as irritation or sensitization, remains limited. The present invention is directed to the transdermal administration of 2-methyl-10-(4-methyl-1-piperazinyl)-4H-thieno 2,3-b! 1,5!benzodiazepine, also known as "olanzapine." The drug is described in U.S. Pat. No. 5,229,382 to Chakrabarti et al., issued Jul. 20, 1993, and assigned to Lilly Industries Limited. Reference may be had thereto for any information concerning methods for synthesizing or using olanzapine not explicitly included herein. ##STR1## Olanzapine Olanzapine is a novel antagonist of dopamine at the D-1 and D-2 receptors, and in addition has antimuscarinic anticholinergic properties and antagonist activity at 5HT-2 receptor sites and at noradrenergic α-receptors (Moore et al., J. Pharmacol. Exp. Ther. 262(2):545-551 (1992)). The drug has relaxant, anxiolytic and anti-emetic properties, and, as explained in the Chakrabarti et al. patent referenced above, is useful in the treatment of psychosis, acute mania and mild anxiety states, and is particularly useful in the treatment of schizophrenia and schizophreniform illnesses. Earlier methods for treating schizophrenia typically involved the use of the antipsychotic agents haloperidol, clozapine and flumezapine (7-fluoro-2-methyl-10-(4-methyl-1-piperazinyl)-4H-thieno 2,3-b! 1,5!benzodiazepine). However, as explained in U.S. Pat. No. 5,229,382 to Chakrabarti et al., these drugs were problematic in a number of ways. Haloperidol was found to cause a high incidence of extra pyramidal symptoms, e.g., Parkinsonism, acute dystonic reactions, akathisia, tardive dyskinesia and tardive dystonia. While clozapine was claimed to be substantially free of such extra pyramidal symptoms, it was found to cause agranulocytosis in some patients, a condition resulting in a lowered white blood cell count to a potentially life-threatening degree. Flumazepine was found to result in still additional problems, leading to termination of clinical trials before commercialization, the problems primarily related to an unacceptably high levels of certain enzymes, e.g., creatinine phosphokinase, serum glutamate oxalacetic transaminase and serum glutamate pyruvate transaminase. A related drug, chlorpromazine, has also been found to give rise to a number of problems. Olanzapine has been developed as a drug which is highly effective in the treatment of psychosis, acute mania and mild anxiety states. Olanzapine has been found to be a very safe and effective antipsychotic agent which does not appear to give rise to extra pyramidal symptoms, agranulocytosis, or unacceptably high enzyme levels. Olanzapine has been established to be more potent than clozapine in blocking 5HT2 and dopamine-D2 in studies in rodents (Fuller et al., Research Communications in Chemical and Pathology and Pharmacology 77:1187-1193 (1992)). Additionally, in Phase II, double-blind, randomized, placebo controlled clinical trials, it was concluded that olanzapine is effective in treating both the positive and negative symptoms of schizophrenia and is well-tolerated (P.V. Tran et al., Neuropsychopharmacology 10(3):267S, suppl., pt. 2 (1994)). Currently, olanzapine is administered orally or by injection. While, as alluded to above, the drug is an extremely effective antipsychotic agent, drug non-compliance is a serious problem, and is believed to account for approximately one-third of all short-stay hospital costs. Transdermal administration of olanzapine, as disclosed and claimed herein, significantly enhances patient compliance by providing an advanced delivery system useful for administering the drug over an approximately three- to seven-day period. There are a number of other advantages to administering olanzapine transdermally as well: gastrointestinal and other side effects associated with oral administration are substantially avoided; continuous delivery provides for sustained blood levels; the transdermal patch is easily removable if any side effects do occur; and the likelihood of patient acceptance is significantly improved. In general, steady-state, transdermal delivery of the drug seems to provide a far better side effect profile overall than is associated with oral administration. None of the art of which applicants are aware describes a transdermal drug delivery system for administering olanzapine. Nor does the art set forth data on skin permeability or therapeutic administration rates with respect to such compounds. To the best of applicants' knowledge, then, the transdermal administration of olanzapine is unknown and completely unsuggested by the art. SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to address the above-mentioned need in the art by providing methods, pharmaceutical formulations and systems for the transdermal administration of olanzapine or a pharmaceutically acceptable acid addition salt thereof. It is another object of the invention to provide a method for treating psychosis, acute mania or mild anxiety states, particularly schizophrenia or schizophreniform illnesses, by administering olanzapine or a pharmaceutically acceptable acid addition salt thereof through a predetermined area of intact skin or mucosal tissue for a time period and at an administration rate effective to alleviate the symptoms at issue. It is still another object of the invention to provide such a method which involves the transdermal administration of a pharmaceutically acceptable acid addition salt of olanzapine. It is a further object of the invention to provide such a method in which olanzapine or a pharmaceutically acceptable acid addition salt thereof is administered in conjunction with a skin permeation enhancer. It is a further object of the invention to provide olanzapine-containing compositions formulated for transdermal delivery. It is still a further object of the invention to provide a "solid matrix" type transdermal system for administering olanzapine as provided herein which comprises a laminated composite of a backing layer and a contact adhesive layer which contains the drug and serves as the basal surface which contacts the skin or mucosal tissue during use. It is yet a further object of the invention to provide a transdermal system for administering olanzapine as provided herein which comprises a laminated composite of a backing layer, a contact adhesive layer which serves as the basal surface and contacts the skin or mucosal tissue during use, and, incorporated therebetween, a polymeric matrix which contains the drug and serves as the drug reservoir. It is still a further object of the invention to provide a transdermal system for administering olanzapine as provided herein, in the form of a patch having an internal reservoir of a liquid, gel or foam with the drug dispersed or adsorbed therein. Still further objects of the invention are to provide transdermal systems for administering olanzapine, containing high capacity polyurethane hydrogel drug reservoirs or reservoirs of superabsorbent material as will be described elsewhere herein. Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. In one aspect of the invention, a method is provided for treating an individual suffering from or susceptible to psychosis, acute mania or mild anxiety states, particularly schizophrenia and schizophreniform illnesses, by transdermally administering a therapeutically effective amount of olanzapine or a pharmaceutically acceptable acid addition salt thereof, for a time period and at an administration rate effective to alleviate the symptoms at issue. The method is premised on the discovery that olanzapine and pharmaceutically acceptable salts thereof may be administered through the skin or mucosal tissue to achieve desired systemic effects. In a preferred embodiment, a skin permeation enhancer is coadministered with the drug so as to increase permeability thereto and achieve more rapid delivery. It should be noted that while the present invention is directed to the treatment of individuals suffering from or susceptible to psychosis, acute mania or mild anxiety states, and is particularly useful in the treatment of schizophrenia or schizophreniform illnesses, the present method may extend to any use of olanzapine deriving from its activity an antagonist of dopamine at the D-1 and D-2 receptors, its antimuscarinic anti-cholinergic properties, and/or its antagonist activity at 5HT-2 receptor cites and noradrenergic α-receptors. In another aspect of the invention, a therapeutic system for transdermal administration of olanzapine is provided. The system is a laminated composite comprising a backing layer, a drug reservoir, and a means for affixing the composite to the skin. The drug reservoir and the affixing means may be distinct, such that a separate contact adhesive layer is provided which serves as the basal surface of the device, or the drug reservoir may itself be comprised of an adhesive layer which is suitable for contacting and adhering to the skin. Such therapeutic systems are in the nature of "solid matrix" type transdermal patches. Alternative systems, containing the drug in a liquid, gel or foam reservoir, may, however, be used as well. The transdermal system is preferably constructed such that an effective dose of olanzapine or a pharmaceutically acceptable acid addition salt thereof will be delivered for a period in the range of about three to seven days. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates in schematic form one embodiment of a solid matrix-type transdermal delivery system which may be used in conjunction with the present invention. FIG. 2 illustrates in schematic form an alternative embodiment of a solid matrix-type transdermal delivery system which may be used in conjunction with the present invention. FIG. 3 illustrates in schematic form a liquid reservoir-type transdermal delivery system which may be used in conjunction with the present invention. FIGS. 4-13 are graphs illustrating olanzapine flux obtained using various vehicles and prototypes, as described in the Examples herein. DETAILED DESCRIPTION OF THE INVENTION Before describing the present invention in detail, it is to be understood that this invention is not limited to particular formulations or transdermal systems as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It must be noted that, as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to "a permeation enhancer" includes a mixture of two or more permeation enhancers, reference to "an excipient" or "a vehicle" includes mixtures of excipients or vehicles, reference to "an adhesive layer" includes reference to two or more such layers, and the like. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present invention, the preferred materials and methods are described herein. In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. By "transdermal" delivery, applicants intend to include both transdermal (or "percutaneous") and transmucosal administration, i.e., delivery by passage of a drug through the skin or mucosal tissue and into the bloodstream. By "therapeutically effective" amount is meant a nontoxic but sufficient amount of a compound to provide the desired therapeutic effect, in the present case, that dose of olanzapine which will be effective in relieving or preventing symptoms of psychosis, acute mania, mild anxiety, or the like. An "effective" amount of a permeation enhancer as used herein means an amount that will provide the desired increase in skin permeability and, correspondingly, the desired depth of penetration, rate of administration, and amount of drug delivered. By "predetermined area of skin" is intended a defined area of intact unbroken living skin or mucosal tissue. That area will usually be in the range of about 1 cm 2 to about 100 cm 2 , more usually in the range of about 20 cm 2 to about 60 cm 2 . However, it will be appreciated by those skilled in the art of transdermal drug delivery that the area of skin or mucosal tissue through which drug is administered may vary significantly, depending on patch configuration, dose, and the like. When transdermal administration of "olanzapine" per se is indicated herein, it is to be understood that the described method, formulation or system extends to pharmaceutically acceptable acid addition salts as well. "Penetration enhancement" or "permeation enhancement" as used herein relates to an increase in the permeability of skin to a pharmacologically active agent, i.e., so as to increase the rate at which the drug permeates through the skin and enters the bloodstream. The enhanced permeation effected through the use of such enhancers can be observed by measuring the rate of diffusion of drug through animal or human skin using a diffusion cell apparatus as described in the Examples herein. "Carriers" or "vehicles" as used herein refer to carrier materials suitable for transdermal drug administration, and include any such materials known in the art, e.g., any liquid, gel, solvent, liquid diluent, solubilizer, or the like, which is nontoxic and which does not interact with other components of the composition in a deleterious manner. Examples of suitable carriers for use herein include water, silicone, liquid sugars, waxes, petroleum jelly, and a variety of other materials. The term "carrier" or "vehicle" as used herein may also refer to stabilizers, crystallization inhibitors, or other types of additives useful for facilitating transdermal drug delivery. The present method of transdermally delivering olanzapine may vary, but necessarily involves application of a composition containing olanzapine or a pharmaceutically acceptable acid addition salt thereof to a predetermined area of the skin or mucosal tissue for a period of time sufficient to provide an effective blood level of drug for a desired period of time. The method may involve direct application of the composition as an ointment, gel, cream, or the like, or may involve use of a drug delivery device as taught in the art, e.g., in commonly assigned U.S. Pat. Nos. 4,915,950, 4,906,463, 5,091,186 or 5,246,705, or as described below. As noted above, olanzapine may be administered as the base or in the form of a pharmaceutically acceptable acid addition salt. As will be appreciated by those skilled in the art, the base form of the drug can be converted to an acid addition salt by treatment with a stoichiometric excess of a selected acid. Such acid addition salts may be formed, for example, with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like, or with organic acids such as acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, malic acid, malonic acid, succinic acid, maleic acid, hydroxymaleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, naphthalene-2-sulfonic acid, salicylic acid and the like. It will generally be necessary to administer olanzapine or an acid addition salt thereof in conjunction with a permeation enhancer. Suitable enhancers include, but are not limited to, dimethylsulfoxide (DMSO), dimethyl formamide (DMF), N,N-dimethylacetamide (DMA), decylmethylsulfoxide (C 10 MSO), polyethylene glycol monolaurate (PEGML), propylene glycol (PG), propylene glycol monolaurate (PGML), glycerol monolaurate (GML), methyl laurate (ML), lauryl lactate (LL), isopropyl myristate (IPM), terpenes such as menthone, C 2 -C 6 alkanediols, particularly 1,2-butanediol, lecithin, the 1-substituted azacycloheptan-2-ones, particularly 1-n-dodecylcyclazacycloheptan-2-one (available under the trademark Azone® from Whitby Research Incorporated, Richmond, Va.), alcohols, and the like. Vegetable oil permeation enhancers, as described in commonly assigned U.S. Pat. No. 5,229,130 to Sharma, may also be used. Such oils include, for example, safflower oil, cotton seed oil and corn oil. One group of preferred enhancers for use in conjunction with the transdermal administration of olanzapine and acid addition salts thereof are esters given by the formula CH 3 (CH 2 ) m COO! n R in which m is an integer in the range of 8 to 16, n is 1 or 2, and R is a lower alkyl (C 1 -C 3 ) residue that is either unsubstituted or substituted with one or two hydroxyl groups. In the preferred embodiment herein, the ester component is a lower alkyl (C 1 -C 3 ) laurate (i.e., m is 10 and n is 1), and in a particularly preferred case is "PGML." It will be appreciated by those skilled in the art that the commercially available material sold as "PGML" is typically a mixture of propylene glycol monolaurate itself, propylene glycol dilaurate, and either propylene glycol, methyl laurate, or both. Thus, the terms "PGML" or "propylene glycol monolaurate" as used herein are intended to encompass both the pure compound as well as the mixture that is typically obtained commercially. Also preferred are fatty acids and fatty alcohols corresponding to the above-defined fatty esters. Thus, fatty acids useful as permeation enhancers herein will generally have the formula CH 3 (CH 2 ) m COOH, where m is as above, while the fatty alcohols will have the formula CH 3 (CH 2 ) m CH 2 OH Other preferred enhancer compositions are wherein a fatty ester as described above is combined with an ether component selected from the group consisting of diethylene glycol monoethyl ether and diethylene glycol monomethylether. Such enhancer compositions are described in detail in U.S. Pat. Nos. 5,053,227 and 5,059,426 to Chiang et al., both of common assignment herewith. Particularly preferred permeation enhancers are selected from the group consisting of C 2 -C 6 alkanediols, fatty esters having the structural formula CH 3 (CH 2 ) m COO! n R, fatty acids having the structural formula CH 3 (CH 2 ) m COOH, fatty alcohols having the structural formula CH 3 (CH 2 ) m CH 2 OH, and mixtures thereof. The amount of enhancer present in the composition will similarly depend on a number of factors, e.g., the strength of the particular enhancer, the desired increase in skin permeability, rate of administration, and amount of drug delivered. The drug reservoir used in a transdermal system for administering olanzapine will generally comprise on the order of 20 wt. % to 80 wt. % reservoir material (e.g., adhesive polymer, hydrogel, or the like), with the remainder of the reservoir comprised of drug formulation, i.e., olanzapine, enhancer, and any carriers or vehicles which may be used. Typically, although not necessarily, the drug formulation will contain on the order of 1 wt. % to 20 wt. % olanzapine and, correspondingly, 80 wt. % to 99 wt. % enhancer and other vehicles. In this way, the composition may be optimized to produce a transdermal system capable of delivering olanzapine over an approximately three- to seven-day period (with patches worn for longer periods generally corresponding to lower dose systems). One type of transdermal system for transdermally administering an indolone compound of Formula (I) is "solid matrix" type system shown in FIG. 1. The composite, generally designated 10, comprises a backing layer 11, a reservoir layer 12 containing drug 12a either dispersed therein, or adsorbed or absorbed by a particulate hydrophilic material, and a release liner 13. The backing layer 11 functions as the primary structural element of the device and provides the device with much of its flexibility, drape and, preferably, occlusivity. The material used for the backing layer should be inert and incapable of absorbing drug, enhancer or other components of the pharmaceutical composition contained within the device. The backing is preferably made of one or more sheets or films of a flexible elastomeric material that serves as a protective covering to prevent loss of drug and/or vehicle via transmission through the upper surface of the device, and will preferably impart a degree of occlusivity to the device, such that the area of the skin covered on application becomes hydrated. The material used for the backing layer should permit the device to follow the contours of the skin and be worn comfortably on areas of skin such as at joints or other points of flexure, that are normally subjected to mechanical strain with little or no likelihood of the device disengaging from the skin due to differences in the flexibility or resiliency of the skin and the device. Examples of materials useful for the backing layer are polyesters, polyethylene, polypropylene, polyurethanes and polyether amides. The layer is preferably in the range of about 15 microns to about 250 microns in thickness, and may, if desired, be pigmented, metallized, or provided with a matte finish suitable for writing. The reservoir layer 12 in FIG. 1 doubles as the means for containing drug and as an adhesive for securing the device to the skin during use. That is, as release liner 13 is removed prior to application of the device to the skin, reservoir layer 12 serves as the basal surface of the device which adheres to the skin. Reservoir layer 12 is comprised of a pressure-sensitive adhesive suitable for long-term skin contact. It must also be physically and chemically compatible with olanzapine or the acid addition salt thereof, and the carriers and vehicles employed. The reservoir layer will generally range in thickness from about 1 to about 100 microns, preferably in the range of approximately 20 to 75 microns. Suitable materials for this layer include, for example, polysiloxanes, polyisobutylenes, polyacrylates, polyurethanes, plasticized ethylene-vinyl acetate copolymers, low molecular weight polyether amide block polymers (e.g., PEBAX), tacky rubbers such as polyisobutene, polystyrene-isoprene copolymers, polystyrene-butadiene copolymers, and mixtures thereof. Presently preferred adhesive materials for use as reservoir layer 12 are acrylates, silicones and polyurethanes. Release liner 13 is a disposable element which serves to protect the device prior to application. Typically, the release liner is formed from a material impermeable to the drug, vehicle and adhesive, and which is easily stripped from the contact adhesive. Release liners are typically treated with silicone or fluorocarbons. Silicone-coated polyester is presently preferred. In a variation on this embodiment, reservoir layer 12 comprises a matrix of a continuous hydrophobic polymer phase, with a particulate phase of a hydrated inorganic silicate and drug adsorbed or absorbed thereby. Such a system is described, for example, in co-pending, commonly assigned U.S. Patent application Ser. No. 08/056,076, filed Apr. 30, 1993, and entitled "Two-Phase Matrix for Sustained Release Drug Delivery Device" (published internationally as W094/07468 on Apr. 14, 1994). As explained in that application, polymers which may be used as the continuous hydrophobic phase are polysiloxanes, polyisobutylene, solvent-based hydrophobic polyacrylates, polyurethanes, plasticized ethylene-vinyl acetate copolymers, low molecular weight polyether block amide copolymers, styrene-butadiene polymers, and vinyl acetate-based adhesives, with the hydrophobic polymer normally constituting about 30 wt. % to 95 wt. %, more typically 40 wt. % to 60 wt. %, of the matrix. The dispersed inorganic silicate is in the form of particulates that are typically in the non-colloidal size range of 0.001 to 0.1 mm, more usually 0.01 to 0.05 mm. Preferably, the matrix in this embodiment additionally contains a dispersing agent which aids in maintaining the particulate phase dispersed in the continuous phase. Anionic, cationic, amphoteric or nonionic dispersing agents may be used. Preferably, the dispersing agent is a non-ionic surfactant such as a polyethylene-polyoxypropylene glycol copolymer (e.g., that sold under the "Pluronic" trademark) or a polyoxyethylene sorbitan ester (e.g., that sold under the "Tween" trademark); the dispersing agent will normally constitute about 0.5 wt. % to 10 wt. % of the matrix, more usually 3 wt. % to 6 wt. % of the matrix. These matrices are prepared by dissolving the drug in water (with, optionally, additional hydrophilic polar solvents) and contacting the hydrophilic particulate material with the resulting solution to permit the aqueous solution to be absorbed by the particulate material. The mixture will typically have the texture of a paste. The hydrophobic components of the matrix and the dispersing agent, preferably in admixture, are added to the paste with vigorous mixing to form a viscous dispersion. This dispersion may be formed into appropriate shapes and excess solvent removed therefrom. FIG. 2 illustrates a different type of laminated composite that may serve as the transdermal delivery system herein. That system is shown generally at 14, with backing layer 15, drug reservoir 16, contact adhesive layer 17, and release liner 18. The backing layer and release liner are as described above with respect to the structure of FIG. 1. With regard to drug reservoir 16 and contact adhesive layer 17, suitable materials are as described above, e.g., polysiloxanes, polyisobutylenes, polyacrylates, polyurethanes, plasticized ethylene-vinyl acetate copolymers, low molecular weight polyether amide block polymers, tacky rubbers, and mixtures thereof. FIG. 3 depicts an alternative device structure for administering olanzapine or a salt thereof transdermally. The device is a "liquid reservoir" type and is generally designated 18. It comprises a top, impermeable backing layer 19, an underlying liquid, gel (e.g., a hydrogel as described below) or foam layer 20, generally a liquid layer, containing the drug and any associated materials, e.g., enhancers or the like, that is sealed at its edge to the overlying backing layer to form a pouch between the backing and the underlying modulator layer 21, and a pressure-sensitive adhesive layer 22 that serves as the basal surface of the device and affixes the device to the skin during use. The modulator layer is generally a thin, flexible layer of a highly porous material such as polyester, polyethylene, polypropylene, or the like. As with the above embodiments, the device of FIG. 3 is provided with a release liner (not shown) to protect adhesive layer 22 prior to use. Such devices are described, for example, in commonly assigned U.S. Pat. No. 5,124,157 to Colley et al. Such transdermal drug delivery systems for use in conjunction with the administration of olanzapine or salts thereof can be fabricated using conventional techniques which are within the skill of the art, and/or explained in the literature. In general, devices of the invention are fabricated by solvent evaporation film casting, thin film lamination, die cutting, or the like. Particularly preferred transdermal systems for administering olanzapine are those containing high capacity polyurethane hydrogel drug reservoirs, as described in commonly assigned U.S. patent application Ser. No. 08/528,105, entitled "TRANSDERMAL DRUG DELIVERY SYSTEMS HAVING POLYURETHANE HYDROGEL DRUG RESERVOIRS, AND ASSOCIATED METHODS OF MANUFACTURE AND USE," as well as those containing drug reservoirs fabricated from "superabsorbent" materials, such as described in commonly assigned U.S. patent application Ser. No. 08/528,655 entitled "TRANSDERMAL DRUG DELIVERY SYSTEMS HAVING SUPERABSORBENT DRUG RESERVOIRS, AND ASSOCIATED METHODS OF MANUFACTURE AND USE," now abandoned. Briefly, transdermal systems containing high capacity, polyurethane hydrogel reservoirs are fabricated by crosslinking a polyurethane with a catalyst in the presence of water, or by photocuring in the presence of photoinitiator, in the presence of water. Drug formulation is incorporated into the hydrogel so formed, either during or after manufacture. As explained in the above-cited commonly assigned U.S. patent application, it is preferred that the hydrogel be fabricated such that the polyurethane starting material is crosslinked with an aliphatic, cycloaliphatic or aromatic diisocyanate in the presence of water, and that the drug formulation be absorbed therein following hydrogel formation. A laminated composite, containing the drug-containing hydrogel reservoir, a backing layer, optional additional layers such as a contact adhesive layer and a rate-controlling membrane, is then prepared, to serve as the delivery system to be affixed to the skin or mucosal tissue. Drug reservoirs fabricated from superabsorbent materials are typically comprised of crosslinked polymers capable of absorbing at minimum 15 g drug formulation per g superabsorbent material (although polymers capable of absorbing far greater quantitites of drug formulation may be used as well). Examples of such superabsorbent materials, as explained in the above-identified patent application, are olefin/alkyl carboxylate copolymers, e.g., maleic anhydride-isobutylene copolymer, although other superabsorbent materials may also be used. As with the hydrogel-based system, a laminated composite may be prepared using conventional techniques, and serves as the transdermal drug delivery system. In any of these transdermal systems, it may be desirable to include a rate-controlling membrane between the drug reservoir and a contact adhesive layer, when one is present. The materials used to form such a membrane are selected to limit the flux of non-drug components, i.e., enhancers, vehicles, and the like, from the drug reservoir, while not limiting the flux of drug. Representative materials useful for forming rate-controlling membranes include polyolefins such as polyethylene and polypropylene, polyamides, polyesters, ethylene-ethacrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl methylacetate copolymer, ethylene-vinyl ethylacetate copolymer, ethylene-vinyl propylacetate copolymer, polyisoprene, polyacrylonitrile, ethylene-propylene copolymer, and the like. A particularly preferred material useful to form the rate controlling membrane is ethylene-vinyl acetate copolymer. It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, that the description above as well as the examples which follow are intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains. In the following examples, efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperature, etc.) but some experimental error and deviation should be accounted for. Unless indicated otherwise, temperature is in degrees C. and pressure is at or near atmospheric. All patents, patent applications, and publications mentioned herein, both supra and infra, are hereby incorporated by reference. Experimental Materials and Methods Olanzapine free base was provided by Eli Lilly. All chemicals were reagent grade. In Vitro Skin Permeation of Olanzapine Skin Preparation: Human cadaver skin was used for the permeation studies. The frozen skins were thawed and the epidermal layers (stratum corneum and viable epidermis) were separated from the full-thickness skin by immersing it in water at 60° C. for two min. This epidermis was either used immediately for flux studies or stored at -20° C. for later studies. Skin permeation from vehicles: Modified Franz diffusion cells were used for evaluating the performance of vehicles for olanzapine delivery. The receiver compartment was filled with 7.5 ml of pH 7.4 buffer. Quantites ranging from 200 to 500 μl of the selected vehicles saturated with olanzapine were then placed into the donor compartment to initiate the skin flux experiments. The temperature of the diffusion cell contents was maintained at 32° C.±1° C. At predetermined times, the entire receiver content was withdrawn and replaced with fresh buffer. Samples were assays by HPLC. Skin permeation from prototypes: Modified Franz cells were used for evaluating the prototype systems for delivery of olanzapine. The prototype systems were peeled off the polyester release liner and placed on top of the epidermis with the drug adhesive layer facing the stratum corneum. Gentle pressure was applied to insure full contact between the drug adhesive layer and the stratum corneum. The skin membrane with the olanzapine prototype system was then mounted carefully between the donor and the receiver compartments. The receiver compartment was filled with pH 7 buffer and the temperature was maintained at 32° C.±1° C. throughout the experimental period. The entire receiver content was withdrawn and replaced with fresh buffer. Samples were assayed by HPLC. Flux determination: Skin flux (μg/cm 2 /hr) was determined from the steady-state slope of the plot of the cumulative amount of olanzapine permeated through the skin versus time. After steady state had been established, the linear portion of the plot was used to calculate the flux from the slope. For some formulations, the steady state was not achieved, and the data were plotted as flux (μg/cm 2 /hr) at each time point (dividing the quantity penetrating the skin during each time period, corrected for surface area by the time of penetration through the skin). Each formulation was run in triplicate, and the values reported represent the mean and standard deviation for three cells. Skin Irritation Studies The primary skin irritation potential of olanzapine formulations were determined. A Draize irritation protocol was used, as follows. The backs of six rabbits were clipped free of hair, and six different test materials were applied in small Hilltop chambers (0.2 ml) to the skin and worn for 24 hours. For the preliminary prototype, the system was applied to the rabbit skin, occluded using a release liner, and kept in place by means of an adhesive tape. The skin sites were scored according to the Draize scale at 24, 48 and 72 hours after application of the test materials. Mean primary irritation scores are as follows. Range of values: 0, non-irritating; 0-1.9, mildly irritating; 2-5.9, moderately irritating; and 6-8.0, severely irritating EXAMPLE 1 Olanzapine was dissolved in a combination of two vehicles (as indicated in Table 1) and applied to human cadaver skin using a Franz diffusion cell. At predetermined time intervals, as shown in FIGS. 4-8, the whole receiver fluid was replaced with fresh fluid and analyzed for olanzapine using HPLC method. The formulations are listed in Table 1 and the flux data are illustrated in graph form in FIGS. 4-8. TABLE 1______________________________________Formulation______________________________________1. 90% 1,2-butanediol + 10% PGML2. 10% 1,2-butanediol + 90% PGML3. 25% 1,2-butanediol + 75% PGML4. 75% 1,2-butanediol + 25% PGML5. 90% 1,2-butanediol + 10% LL6. 10% 1,2-butanediol + 90% LL7. 25% 1,2-butanediol + 75% LL8. 75% 1,2-butanediol + 25% LL9. 10% 1,2-butanediol + 90% LL10. 90% 1,2-butanediol + 10% IPM11. 25% 1,2-butanediol + 75% IPM12. 75% 1,2-butanediol + 25% IPM13. 100% ML14. 10% 1,2-butanediol + 90% ML15. 90% 1,2-butanediol + 10% ML16. 25% 1,2-butanediol + 75% ML17. 90% 1,2-butanediol + 10% Menthone18. 10% 1,2-butanediol + 90% Menthone19. 25% 1,2-butanediol + 75% Menthone20. 50% 1,2-butanediol + 50% Menthone______________________________________ ML: Methyl Laurate, LL: Lauryl lactate, IPM: Isopropyl myristate. EXAMPLE 2 Olanzapine was dissolved in a combination of three vehicles (as indicated in Table 2). The procedure of Example 1 was followed to evaluate in vitro flux. The formulations are listed in Table 2 and the results are shown in FIG. 9. TABLE 2______________________________________Formulation______________________________________1. 10% Oleic acid + 45% PGML + 45% 1,2-butanediol2. 10% Oleyl alcohol + 45% PGML + 45% 1,2-butanediol3. 10% Methyl laurate + 45% Lauryl lactate + 45% 1,2-butanediol4. 10% Lauric acid + 45% PGML + 45% 1,2-butanediol5. 10% Lauric acid + 45% Methyl Laurate + 45% 1,2- butanediol6. 10% Capric acid + 45% Lauryl lactate + 45% 1,2- butanediol7. 10% Benzyl alcohol + 45% PGML + 45% 1,2- butanediol8. 10% Oleic acid + 45% Methyl decanoate + 45% 1,2- butanediol 1109. 10% Capric acid + 90% Methyl Laurate______________________________________ ML: Methyl laurate; LL: Laurolactate; OA: Oleic acid; TG: Thioglycerol; PG: Propylene glycol EXAMPLE 3 Olanzapine was dissolved in a combination of vehicles (as indicated in Table 3) and absorbed onto a highly absorbent maleic anhydride-isobutylene copolymeric film, obtained from Concert Industries Limited, Thurso, Quebec, Canada. The systems were cut into 1.25 cm 2 circles and applied onto the skin as in Example 1. The formulations are listed in Table 3 and the results are shown in FIG. 10. TABLE 3______________________________________Formulation______________________________________1. Saturated olanzapine in vehicle of 10% lauric acid + 45% Methyl laurate + 45% 1,2-butanediol adsorbed on two pieces 1.25 cm.sup.2 each of superabsorbent film (Concert 100136 #95068)2. Saturated olanzapine in vehicle of 10% Oleyl alcohol + 45% PGML + 45% 1,2-butanediol adsorbed on two pieces 1.25 cm.sup.2 each of superabsorbent film (Concert 100136 #95068)3. Saturated olanzapine in vehicle of 10% Oleic acid + 45% Methyl caprate + 45% 1,2-butanediol adsorbed on two pieces 1.25 cm.sup.2 each of superabsorbent film (Concert 100136 #95068)______________________________________ EXAMPLE 4 Olanzapine was dissolved in a combination of vehicles (see Table 4) and absorbed on a superabsorbent material as in Example 3. At the same time, a an ethylene vinyl acetate membrane was cut into 2 cm 2 circles and mounted onto the skin. Following this procedure, the polymeric film having drug absorbed thereon was applied and the procedure of Example 1 was followed. The formulations are listed in Table 4 and the results are shown in FIG. 11. TABLE 4______________________________________Formulation______________________________________1. Olanzapine saturated in 10% Lauric acid + 45% methyl Laurate + 45% 1,2-butanediol and absorbed on superabsorbent film (Concert 100136 with EVA 19%, 4 mil membrane).2. Olanzapine saturated in 10% Oleic acid + 45% methyl caprate + 45% 1,2-butanediol and absorbed on superabsorbent film (Concert 100136 with EVA 19%, 4 mil membrane).______________________________________ EXAMPLE 5 Olanzapine was dissolved in a combination of vehicles (see Table 5) and was added with water to Hypol® PreMA G-50 polymer (Hampshire Chemical Corporation) (ratio of water:polymer was approximately 2:1) and mixed together until a hydrogel was formed. The gel was cut into 2 cm 2 area circles and applied onto the skin as in Example 1. The formulations are listed in Table 5 and the results are shown in FIG. 12. TABLE 5______________________________________Formulation______________________________________1. Hydrogel G-50 contains 25% Solution of saturated olanzapine in (10% Methyl Laurate + 45% Lauryl lactate + 45% 1,2-butanediol)2. Hydrogel G-50 contains 25% Solution of saturated olanzapine in (10% Lauric acid + 45% Lauryl lactate + 45% 1,2-butanediol)______________________________________ EXAMPLE 6 Olanzapine was dissolved in a combination of vehicles (as indicated in Table 6). Water was added to Hypol® PreMA G-50 polymer (Hampshire Chemical Corporation) (ratio of water:polymer was approximately 2:1) and mixed together until a hydrogel was formed. The gel was cut into 2 cm 2 circles which were then soaked with the olanzapine-vehicles combination overnight. The final product was applied onto the skin as in Example 1. The formulations are listed in Table 6 and the results are shown in FIG. 13. TABLE 6______________________________________Formulation______________________________________1. Olanzapine saturated in 10% Lauric acid + 45% methyl Laurate + 45% 1,2-butanediol and left overnight with Hypol PreMA gel.2. Olanzapirie saturated in 10% Oieic acid + 45% methyl Caprate + 45% 1,2-butanediol and left overnight with Hypol PreMA gel.______________________________________ EXAMPLE 7 Results of the irritation studies conducted as explained above were as follows: TABLE 7______________________________________Primary Irritation Score (Draize Score)Formulation Draize Score______________________________________1. Olanzapine saturated in PGML 2.32. Olanzapine saturated in 10% Oleyl 1.4 alcohol + 45% Methyl Caprate + 45% 1,2-butanediol and absorbed on the superabsorbent and a membrane (EVA 19%) was put in between the skin and the superabsorbent3. Olanzapine saturated in 10% Oleic 1.4 acid + 45% Methyl Caprate + 45% 1,2-butanediol and absorbed on the superabsorbent and a membrane (EVA 19%) was put in between the skin and the superabsorbent4. Olanzapine saturated in 10% Lauric 1.4 acid + 45% Methyl laurate + 45% 1,2-butanediol and absorbed on the superabsorbent and a membrane (EVA 19%) was put in between the skin and the superabsorbent5. Olanzapine saturated in 10% oleyl 1.7 alcohol + 45% Methyl Caprate + 45% 1,2-butanediol in a Hypol PreMA G- 50 Hydrogel6. Olanzapine saturated in 10% Lauric 2.2 acid + 45% Methyl Laurate + 45% 1,2-butanediol in a Hypol PreMA G- 50 Hydrogel______________________________________ As may be concluded from the results set forth in Table 7, irritation resulting from the formulations tested was minimal. It may be concluded from these examples that sufficient skin fluxes of olanzapine can be achieved using any of a variety of enhancers, vehicles and prototypes, such that effective drug doses may be delivered using relatively small transdermal patches.	Transdermal administration of olanzapine and pharmaceutically acceptable acid addition salts thereof is described. The method involves treating an individual suffering from or susceptible to psychosis, acute mania or mild anxiety states, particularly those afflicted with schizophrenia or schizophreniform illnesses, by administering olanzapine or a salt thereof through the skin or mucosal tissue, for a time period and at an administration rate effective to alleviate the symptoms of the disease. Pharmaceutical formulations and drug delivery systems for administering olanzapine are provided as well.	0
CROSS-REFERENCE TO RELATED APPLICATION This is a continuation of application Ser. No. 616,517 filed Sept. 25, 1975 now abandoned. BACKGROUND OF THE INVENTION This invention relates to a process for the recovery of sulfuryl fluoride and sulfuryl chlorofluoride substantially free of undesired chlorine contaminant. In accordance with another aspect, this invention relates to a method of preparing sulfuryl chlorofluoride from a reaction mixture of sulfur dioxide, chlorine and hydrogen fluoride. The preparation of sulfuryl fluoride (SO 2 F 2 ) from an anhydrous gaseous mixture of sulfur dioxide (SO 2 ), chlorine (Cl 2 ) and hydrogen fluoride (HF) in the presence of a catalyst at temperatures of from about 150 to about 450° C., preferably above about 200° C., is conventional in the art. U.S. Pat. Nos. 2,772,144, 3,092,458, and 3,320,030 all relate to such manufacture of SO 2 F 2 while U.S. Pat. No. 2,875,127 relates to the use of SO 2 F 2 as a fumigant. It is the usual prior art practice to pass the SO 2 F 2 product reaction mixture exiting from a reactor through an aqueous scrubber system to recover many of the undesired by-products or unused reactants, e.g., Cl 2 , SO 2 , HCl and SO 2 ClF, before recovering the final product. The presence of free chlorine in the final product is undesired in view of its highly corrosive nature; such free chlorine cannot readily be distilled from the desired product in view of the azeotrope mixture that Applicants believe forms with sulfuryl fluoride and the use of aqueous scrubbers taught in the art is unsatisfactory as they do not completely remove the free chlorine content. Moreover, these methods suffer other disadvantages on account of numerous attendant pollution problems associated with such aqueous effluent waste streams, as well as the economic loss of valuable unused reactants and hydrogen chloride by-product. The production of SO 2 ClF by reacting SO 2 , HF and Cl 2 in the presence of activated carbon catalyst and an alkali metal bifluoride at 100°-200° C. is also taught by the U.S. Pat. No. 3,320,030 mentioned above. Various other processes utilizing different reactants, e.g., KSO 2 F and Cl 2 , SO 2 Cl 2 and SbF 3 , CoF 3 , AgF 2 , MnF 3 , NH 4 F, NH 4 HF 2 and the like are also taught in the art but are not considered as pertinent as the teachings of the U.S. Pat. No. 3,320,030. Accordingly, an object of this invention is to provide an improved process whereby SO 2 F 2 substantially free of chlorine can be obtained without the employment of aqueous scrubbing systems. Another object of the present invention is to provide a method whereby SO 2 ClF can be produced from excess chlorine contained in an SO 2 F 2 product reaction mixture. Other objects and aspects, as well as several advantages of the invention, will become apparent upon consideration of the accompanying disclosure and the appended claims. SUMMARY OF THE INVENTION Unexpectedly, it has been found that if a product reaction mixture resulting from the contacting of sulfur dioxide, chlorine and hydrogen fluoride in the presence of an activated charcoal catalyst is subjected to further reaction, undesired free chlorine present in the product reaction mixture and in the desired final product, SO 2 F 2 , can be substantially eliminated. Thus, in accordance with one embodiment of the invention, a process is provided wherein a product mixture, comprising sulfuryl fluoride and resulting from the reaction of an anhydrous gaseous mixture of sulfur dioxide, chlorine and hydrogen fluoride in the presence of a catalyst comprising activated carbon, is reacted at a reaction temperature of at least about 35° C. and reaction pressures of from atmospheric to about 65 psi in the presence of a catalyst comprising activated carbon, thereby reducing the free chlorine content of said mixture by converting the same to sulfuryl chlorofluoride. In accordance with another embodiment of the invention, the resulting SO 2 ClF is recovered from the SO 2 F 2 product mixture. In still another embodiment, SO 2 F 2 substantially free of chlorine is separated from the product mixture. In another embodiment of the invention, it has unexpectedly been found that an anhydrous gaseous mixture of SO 2 , Cl 2 and HF can be reacted, in the presence of a catalyst comprising activated carbon, directly to a substantially chlorine free SO 2 ClF product under the conditions of the present invention with little or no formation of SO 2 F 2 . Advantageously, the present invention provides a completely anhydrous process by which SO 2 F 2 and SO 2 ClF can be continuously produced substantially free of Cl 2 , thus obviating the steps of product purification by conventional aqueous recovery methods. DESCRIPTION OF PREFERRED EMBODIMENTS The invention is not dependent upon specific reaction conditions concerning the initial formation of the SO 2 F 2 containing product reaction mixture from which undesired free chlorine is to be removed. These conditions are generally well known in the art as set forth in the Background herein. Generally, the product reaction mixture comprising SO 2 F 2 as prepared by the prior art methods also contains SO 2 , HF, HCl and undesired free Cl 2 . A typical such product reaction mixture is prepared by reacting an anhydrous mixture of about 1.0 mole Cl 2 , about 1.35 mole SO 2 and from 2.5 to about 4.5 mole HF. The product reaction mixture thus obtained usually comprises 1.0 mole SO 2 F 2 , 0.35 mole SO 2 , up to about 2.5 mole HF and varying amounts, e.g., from 50 to about 10,000 ppm or more of free Cl 2 . The amount of undesired free Cl 2 may vary considerably depending upon the condition of the carbon catalyst and the amount of Cl 2 initially used. As used herein, the term "Cl 2 removal" is understood to be synonymous with "Cl 2 conversion to SO 2 ClF". Such undesired excess chlorine is substantially, if not completely, reduced by the method of the present invention wherein the SO 2 F 2 product reaction mixture containing free Cl 2 is further reacted over a catalyst comprising activated carbon. Whether or not the excess Cl 2 exists as free excess chlorine per se in the product reaction mixture or as SO 2 Cl 2 is not definitely known. However, SO 2 Cl 2 readily disassociates to SO 2 and Cl 2 or reacts in analysis methods as SO 2 Cl 2 and substantially all of the Cl 2 can, within the limits of detection, irrespectively be removed. The minimum reaction temperature employed to obtain substantial Cl 2 removal may range from about 35° to about 145° C., the exact reaction temperature being dependent upon the reaction pressures and feed rates employed. Reaction pressures of from atmospheric to about 65 psi are typically employed. Usually, a pressure of at least about 1-2 psi is employed to move the reaction mixture through the reactor. It has also been observed that, as the reaction pressure is increased, the reaction temperature must likewise be increased in order to maintain substantial conversion of the free Cl 2 to SO 2 ClF. Thus, at reaction pressures near atmospheric and a reaction temperature of about 35° C., the minimum reaction temperature must generally be increased about 10° C. for every increase of from about 6 to 8 psi in order to maintain the recovery of SO 2 F 2 and/or SO 2 ClF products substantially free of Cl 2 . Thus, for example, at pressures slightly above atmospheric, e.g., 1-2 psi, the minimum temperature required to maintain substantial, if not complete, removal of Cl 2 is about 35-40° C. Temperatures of from about 35 to about as high as 100° C. at this pressure range can be employed and substantial removal of Cl 2 obtained. However, at such pressures, the removal of Cl 2 begins to decrease as the temperature is increased to above about 100° C. The maximum temperature which can be employed to accomplish substantial removal of Cl 2 may thus be higher than the minimum required temperature at a given pressure. Generally, however, the range between the minimum and maximum temperatures wherein substantial Cl 2 removal is obtained will decrease due to reaction kinetics as the operating pressures are increased, the maximum temperature being limited to approximately 145° C. at about 65 psi. The exact minimum and maximum temperatures can, of course, be readily determined by test runs using the Cl 2 analysis methods as hereinafter set forth. Temperatures above or below the maximum or minimum temperatures can, of course, be utilized where the presence of free Cl 2 in the SO 2 F 2 or SO 2 ClF products can be tolerated. For the purposes of the present invention wherein substantial Cl 2 removal by conversion thereof to SO 2 ClF is desired, and where SO 2 F 2 and/or SO 2 ClF products free of Cl 2 are desired, minimum temperatures of from about 35 to about 145° C. and pressures of from about atmospheric to about 65 psi can be employed. Economic considerations in plant construction, etc., dictate that lower pressures ordinarily be utilized. In a preferred embodiment, minimum reaction temperatures of from 40 to about 120° C. at pressures of from atmospheric to about 50 psi are employed. In another preferred embodiment, minimum reaction temperatures of from about 40° to about 100° C. at pressures of from about 2 to about 37 psi are employed. Any of the commercially available activated carbons may be employed as catalysts in the present invention. Advantageously, the process of the present invention effectively converts excess Cl 2 to SO 2 ClF with little apparent effect on the catalyst employed. Another consideration involved in the practice of the present invention is residence or contact time. Those skilled in the art recognize that this element is highly variable depending upon such other factors as reaction temperature, type of apparatus, overall size of a specific operation and the like. For any particular operation with given apparatus equipment, determination of process variables such as optimum reaction temperature, pressure and contact time is within the skill of the art, and may be determined by test run. Generally, the contact time can be from about 1 to 10 or more seconds. Preferably, the contact time of the claimed process is about one-half the contact time of the initial reactants used to prepare the SO 2 F 2 containing reaction mixture. A preferred contact time is from about 1 to about 4 seconds. Apparatus constituting the reactor and related accessories are simple and, along with the product recovery systems following the reactor, may be along the lines described in the appended examples. Those skilled in the art will readily recognize such equipment, as well as other conventional equipment set forth in the references cited in the Background herein which can be employed for the purposes of the present invention. While a second reactor, essentially the same as the first reactor used to react SO 2 , Cl 2 and HF to a product reaction mixture containing SO 2 F 2 , is conveniently employed, the use of a single reactor to accomplish both the formation of SO 2 F 2 and the removal of Cl 2 from such product mixture containing SO 2 F 2 to form SO 2 ClF is within the scope of the present invention. The process of the present invention can be monitored with respect to the removal of Cl 2 and the production of SO 2 ClF by analysis of the gaseous mixture obtained from the reaction. In such operations, a sample of the gaseous mixture is reacted with a propylene and nitrogen mixture and the resulting mixture analyzed by gas phase chromatography for propylene dichloride, which will be formed by reaction with excess Cl 2 or SO 2 Cl 2 present. Amounts as low as about 50 ppm Cl 2 can be detected by such analysis method. The following examples illustrate practice of the invention. EXAMPLE 1 A 10 inch long, three-fourth inch diameter Hastelloy C reactor tube was packed with 9 × 10 mesh PCB coconut charcoal and maintained at a temperature of about 180° C. An anhydrous gaseous mixture comprising about 1.0 mole Cl 2 , about 1.35 moles SO 2 and about 4.5 moles HF was metered thereto at about 12 psi with an average contact time of the mixture in the reactor of about 5 seconds. The product reaction mixture comprising SO 2 F 2 , SO 2 , HF and HCl in mole ratios of about 1.0: .35 : 2.5 : 2.0 and containing detectable amounts of Cl 2 and/or SO 2 Cl 2 was fed into a second similar 5" × 3/4" packed reactor. The temperature of the second reactor was about 65° C. and the pressure was about 12 psi. The product reaction mixture contact time in the second reactor was about 2.5 seconds. Analysis of the mixture exiting the second reactor indicated the presence of SO 2 F 2 , HCl, SO 2 , HF and SO 2 ClF. Reaction of the mixture exiting the second reactor with propylene diluted with nitrogen and analysis of the resulting mixture for propylene dichloride content by means of gas phase chromatography was carried out. Within the limits of detection of the analytical method, no propylene dichloride was found, indicating the absence of Cl 2 or SO 2 Cl 2 in the product mixture. EXAMPLE 2 Utilizing equipment and procedures as in Example 1, the product reaction mixture exiting the first reactor was reacted at about 43° C. and about 2 psi for a period of about 2.5 seconds. The gaseous product mixture exiting the second was similarly analyzed with no detectable Cl 2 being found. In similar operations, it was found that SO 2 F 2 products having no detectable Cl 2 levels could be obtained at temperatures of from about 43 to about 100° C. at a pressure of about 2 psi. EXAMPLE 3 In other operations utilizing a 20 foot long, 2-inch diameter Hastelloy C reactor tube packed with 4 × 10 mesh PCB coconut charcoal catalyst, typical SO 2 F 2 containing reaction mixtures therefrom having from 2000 to 3000 or more ppm Cl 2 have been found to have no detectable Cl 2 or SO 2 Cl 2 levels after treatment in a second similar reactor of 10 feet in length and being operated at about 100° C. and about 35 psi. EXAMPLE 4 A first reactor similar to that described in Example 1 above but having an inactive catalyst producing little or no SO 2 F 2 from the reaction of Cl 2 , SO 2 and HF and producing a product reaction mixture containing some SO 2 ClF and high amounts, i.e., about 20,000 ppm of Cl 2 at about 180° C. and 2 psi was utilized to determine the effect of temperature and catalyst conditions on the removal of Cl 2 . In such operations, the reactor was operated at lower temperatures of about 100° C. at 2 psi and a similar gaseous mixture of about 1.0 mole Cl 2 , 1.35 mole SO 2 and about 4.5 mole HF being fed thereto. The gaseous mixture exiting therefrom was analyzed and found to have no detectable Cl 2 or SO 2 Cl 2 and full conversion to SO 2 ClF. Such results clearly indicate the effectiveness of the present process for preparing a substantially Cl 2 free SO 2 ClF product from SO 2 , HF and Cl 2 and demonstrate that a long catalyst life for the process could be expected. Data from various other runs with other similar equipment confirm the effectiveness of the process in Cl 2 removal and conversion to SO 2 ClF. Various modifications may be made in the process of the present invention without departing from the spirit or scope thereof and it is to be understood that we limit ourselves only as defined in the appended claims.	A product mixture resulting from the reaction of an anhydrous gaseous mixture of sulfur dioxide, chlorine and hydrogen fluoride in the presence of a catalyst is heated at a temperature of at least about 35° C. under pressures up to about 65 psi to effect substantial conversion of undesired free chlorine in the resulting product mixture to sulfuryl chlorofluoride. The conversion of free chlorine to sulfuryl chlorofluoride allows the use of a completely anhydrous process from which uncontaminated sulfuryl fluoride and sulfuryl chlorofluoride products can readily be obtained. A method for the production of sulfuryl chlorofluoride from said gaseous mixture is also provided.	2
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a reset circuit and a reset method. Especially, the present invention relates to a reset circuit and a reset method for a communication device installed in an inaccessible place such as a remote place or a dangerous place like a high-altitude place. [0003] 2. Description of the Prior Art [0004] Generally, for example, a reset circuit is applied to a communication processing circuit. FIG. 1 is a diagram showing a conventional reset circuit. Referring to FIG. 1 , a communication processing circuit 13 is reset by a reset circuit 12 . For resetting, software reset by a switch, software reset by software, power reset by a switch and the like are employed. The communication processing circuit 13 is reset by a system reset pulse 4 and a power reset pulse 6 output from the reset circuit 12 . [0005] The prior art described above is disclosed in the Japanese Patent application laid open No. 2000-276260 and in the Japanese Patent application laid open No. 10-11324. [0006] The conventional reset circuit and the reset method have problems as below. [0007] The first problem is that, in a communication device installed in an inaccessible place such as a remote place or a dangerous place like a high-altitude place where it is difficult to visit, it is difficult to operate the power switch of the main body of the device. [0008] The second problem is that, in a communication device remotely installed, resetting by pressing a switch or resetting by software is impossible when there are problems with firmware or software. [0009] Generally, for resetting a communication device, a switch or a multiplexed control signal has been used for resetting a power source or a system. Especially, in a communication device remotely installed, a power switch cannot be easily operated and the control signal cannot be used for resetting when there are problems with firmware or software of a communication device. SUMMARY OF THE INVENTION [0010] It is therefore an object of the present invention to provide a remote installed communication device with a reset circuit and a reset method for easily operating a system reset or a power reset from distant place. [0011] The present invention, in a reset circuit for a communication device, wherein the device is reset by using link information, from an external interface signal, which indicates whether an external interface is connected or disconnected to a physical layer. [0012] The present invention, in a reset circuit for a communication device, resets a device by judging whether or not a communication is disconnected based on the link information input from an interface circuit connected to an external interface. [0013] It is desirable that the reset circuit have a reset function for judging, based on the link information input by an interface circuit connected to an external interface, whether a communication is connected or disconnected and resetting the communication device if the communication judged to be disconnected. It is desirable that the reset circuit comprise: a link disconnection judging circuit for judging whether or not link is disconnected based on the link information; a system reset circuit for resetting system based on a reset signal from the link disconnection judging circuit; and a power reset circuit for a power disconnection based on a reset signal from the link disconnection judging circuit. [0014] A reset method for a communication device in accordance with the present invention, comprises the steps of judging whether or not a communication is disconnected based on link information which indicates whether a physical layer is connected or disconnected to an external interface; measuring the time from when a communication is judged to be disconnected by the judging step; resetting system when the time measured in the previous step is over the first predetermined time; and/or resetting power when the measured time is over the second predetermined time. Or otherwise, a reset method for a communication device in accordance with the present invention comprises the steps of judging whether or not a communication is disconnected based on link information which indicates whether a physical layer is connected or disconnected to an external interface; measuring the time from when a communication is judged to be disconnected by the judging step; resetting system when the measured time in the previous step is over the first predetermined time; judging whether or not the system up and running correctly after the resetting step; resetting power when the system is not judged to be correctly up and running by the previous step. [0015] It is desirable that the first and the second predetermined times be reconfigured after once having been configured. [0016] In the present invention, a link disconnection judging circuit judges, based on link information input by an interface circuit, whether or not a communication is disconnected. In the previous judgement, when a communication is judged to be disconnected, the link disconnection judging circuit outputs system reset pulse to a system reset circuit and a power reset pulse to a power disconnection circuit, respectively. The system reset circuit, in the case of disconnection of communication, sends reset signals to each section of the device. The power disconnection circuit, based on the reset pulse, stops supplying second power to each section of the device. According to the structure described above, the present invention provides a reset circuit and a reset method for especially a communication device remotely installed. BRIEF DESCRIPTION OF THE DRAWINGS [0017] The above and further objects and novel features of the invention will be more fully understood from the following detailed description when the same is read in connection with the accompanying drawings in which: [0018] FIG. 1 is a block diagram showing a communication device having a conventional reset circuit; [0019] FIG. 2 is a block diagram showing the structure of a principal part including a reset circuit of the present invention; [0020] FIG. 3 is a block diagram showing a communication processing circuit including a reset circuit of the present invention; [0021] FIG. 4 is a timing chart according to the embodiment of the present invention; and [0022] FIG. 5 is a flowchart showing an example of a resetting method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] Referring now to the drawings, a description of preferred embodiments of the present invention will be given in detail. [0024] FIG. 2 is a diagram showing the structure of a reset circuit of the present invention. Referring to FIG. 2 , a link disconnection judging circuit 1 judges, based on link information 3 input by an interface circuit 2 , whether or not a communication is disconnected. In the previous judgement, when a communication is judged to be disconnected, the link disconnection judging circuit 1 outputs a system reset pulse 4 to a system reset circuit 5 and a power reset pulse 6 to a power disconnection circuit 7 , respectively. The system reset circuit 5 sends a reset signal 8 to each section of the device. The power disconnection circuit 7 , based on the power reset pulse 6 , stops supplying a secondary power 10 to each section of the device. [0025] In the structure described above, the present invention provides a reset circuit and a reset method, based on the link information 3 input by the interface circuit 2 , for judging whether or not a communication is disconnected. According to the present invention, in a communication device remotely installed, even in the case of neither being able to be operated easily by a power switch of the main body of a device nor being able to be reset by pressing a switch or by software when there are problems with firmware or software, a system reset or a power reset of a device is surely operated by link disconnected state (stopping inputting an external interface signal) of an external interface signal. [0026] FIG. 3 shows the structure of a radio communication device employing a reset circuit according to the first embodiment. As shown in FIGS. 2 and 3 , a reset circuit 12 in accordance with the present invention comprises the link disconnection judging circuit 1 , the system reset circuit 5 and a power disconnection circuit (power reset circuit) 7 . According to the present invention, a communication processing circuit 13 may comprise the system reset circuit 5 and the power disconnection circuit (power reset circuit) 7 to form a reset circuit of the present invention. [0027] Referring to FIG. 3 , an interface circuit 2 terminates an interface 11 . An ethernet® or an optical interface, for example, may serve as an external interface, but the external interface is not limited to them unless departing from the spirit and the scope of the present invention. The interface 2 is a terminal section for an ethernet® or an optical interface. Signals output by the interface circuit 2 are sent to the communication processing circuit 13 in which modulation or demodulation is conducted and are output from an antenna 14 . [0028] The interface circuit 2 is comprised of a dead end of a physical layer and that of a MAC (Media Access Control) layer of IEEE 802.11. The dead end of the physical layer establishes a connection (link) without interventions such as a control by a CPU (Central Processing Unit). The signal indicating the state of the link is the link information 3 . [0029] FIG. 2 shows the structure of a reset circuit in this embodiment. In FIG. 2 , the link disconnection judging circuit 1 judges, based on the link information 3 input by the interface circuit 2 , whether or not communication is disconnected. In the previous judgement, when a communication is judged to be disconnected, the link disconnection judging circuit 1 outputs the system reset pulse 4 to the system reset circuit 5 and the power reset pulse 6 to the power disconnection circuit 7 , respectively. [0030] In the system reset circuit 5 , the system reset pulse 4 is input from the link disconnection judging circuit 1 to produce the reset signal 8 for resetting each section of the device. In the power disconnection circuit 7 , the power reset pulse 6 is input from the link disconnection judging circuit 1 to stop supplying the secondary power 10 . [0031] As set forth hereinbefore described is the structure and operation of a circuit of the present invention. Since the interface circuit 2 and the communication processing circuit 13 in FIG. 3 are well known to those skilled in the art and are not directly concerned to the present invention, the detailed structures of them are left out. [0032] Next, a description will be given of the operation of the reset circuit shown in FIG. 2 referring to the time chart shown in FIG. 4 . [0033] In FIG. 3 , the link disconnection judging circuit 1 judges whether or not the communication is disconnected. As shown in FIG. 4 , the level “H” indicates that the link is made, and the level “L” indicates that the link is not made. [0034] In the link disconnection judging circuit 1 , the system reset pulse 4 is output at the moment where the period of time has passed from when the link information became “L” level from the “H” level until it lasts for Time 1 . At the moment where the period of time has passed from when the link information became “L” level from “H” level until it lasts for Time 2 , the power reset pulse 6 is output. As shown in the time chart in FIG. 4 , Time 1 is a predetermined time for resetting a system and Time 2 is a predetermined time for resetting a power source. It is agreeable that Time 2 is longer than Time 1 , but it is not limited to that. For instance, Time 1 may be longer than Time 2 . Further, for example, before/after a period of time (one month, three months, six months or one year for example), it is possible to change a relation between Time 1 and Time 2 from Time 2 >Time 1 to Time 2 <Time 1 , and it may be reconfigured that Time 2 is longer than Time 1 after a power reset. With this operation, for example, it is possible to prevent, by the periodical resetting a timed destruction of software caused by viruses or a sudden freeze caused by bugs. Installations of these operations are described in the following embodiment. [0035] As shown in FIG. 5 , the link disconnection judging circuit 1 judges whether or not the communication is disconnected based on the link information (step S 1 ). [0036] When the communication is judged to be disconnected in the link disconnection judging circuit 1 , a disconnected time is measured from when the communication is disconnected and the disconnected time is monitored if it gets to be longer than Time 1 . [0037] In the step S 2 , in the case of Yes, a reset pulse is output for resetting the system (step S 3 ). [0038] In the present invention, as shown in FIG. 4 , it is possible to reset the system when the disconnected time comes to Time 1 , and reset the power when the disconnected time comes to Time 2 . Further, as shown in FIG. 5 , when Time 2 is longer than Time 1 , for example, after the system reset (step S 3 ), the communication processing circuit detects if troubles such as freezing are swept away (step S 4 ). When the system is judged to be abnormal (step S 4 , No), the power source may be reset (step S 5 ). [0039] Referring to FIG. 2 , the system reset circuit 5 resets the system by transmitting the reset signal 8 to each section of the device based on the system reset pulse 4 . The power disconnection circuit 7 resets the power source by stopping supplying the secondary power 10 to each section of the device based on the power reset pulse 6 . [0040] With this operation, a disconnected time is decided by disconnecting a cable of an ethernet® on the opposite side of its radio device for a while or by stopping outputs from an optical cable on the opposite side of its radio device. Depending on the length of the disconnected time of the operation described above, it is possible to reset the system of device or the power. [0041] As a result, it is possible to easily reset a device that cannot be power reset by turning off its power switch, or system reset by software because of its trouble. [0042] A description will be given of another embodiment of the present invention of which the structure is the same as the embodiment described above, but is further characterized by timer setting. In this structure, the timer setting for a system reset and a power reset can be changed programmatically. In this case, after being installed and used, the reset condition can be changed. [0043] For example, it is possible to decide with software the configuration of link disconnection to each external device at respective external devices by storing the history of the link disconnection. Accordingly, a plurality of values of Time 1 (system resetting time) can be configured on software or firmware. Further, the values of Time 1 (system resetting time) for respective external devices can be configured based on each history of link disconnection on software or firmware. For example, it is possible to reconfigure Time 1 as Time 1 n , where Time 1 n is an average of Time 1 , under the condition: Time ⁢ ⁢ 1 n - Time ⁢ ⁢ 1 σ1 / n 1 / 2 > K where n indicates the number of disconnections, vindicates the standard deviation of a system resetting time, and K indicates a predetermined time. Further, as described in the first embodiment, the periodical resetting by a power switch can be made by changing the length of Time 1 and Time 2 . As described above, it is possible to reconfigure Time 1 as Time ln, and then use Time ln and Time 2 respectively, in the same way as the first embodiment. [0044] The present invention allows for resetting from a distant place a communication device remotely installed because the structure enables a system to be reset by link disconnection of an external interface. Accordingly, it is also possible to execute a reset from a distant place by using the link disconnection of an external interface even if a communication device has problems with firmware or software. Further, an agreeable resetting method can be chosen at respective devices because the employment of a system reset and a power reset can be chosen depending on the length of the time of the link disconnection. [0045] While preferred embodiments of the invention have been described using specific terms, the description has been for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.	A reset circuit and a reset method are provided in order to operate a power switch of the main body of a communication device installed in an inaccessible place such as a remote place or a high-altitude place and to execute a reset by software in the case of having problems with firmware or software of a communication device installed in a remote place. In a reset circuit for a communication device, the device is reset by using link information, which indicates whether a physical layer is connected or disconnected to an external interface.	7
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of, and claims priority under 35 U.S.C. §120 on, U.S. application Ser. No. 14/828,270, filed Aug. 17, 2015, which is a continuation of U.S. application Ser. No. 14/580,051, filed Dec. 22, 2014, now U.S. Pat. No. 9,139,015, which is a continuation of U.S. application Ser. No. 14/070,933, filed Nov. 4, 2013, now U.S. Pat. No. 9,033,466, which is a division of U.S. application Ser. No. 13/025,727, filed Feb. 11, 2011, now U.S. Pat. No. 8,602,520, which claims priority under 35 U.S.C. §119 on Japanese patent application nos. 2010-030432 and 2010-233746, filed Feb. 15, 2010 and Oct. 18, 2010 respectively. The content of each such related application is incorporated by reference herein in its entirety. BACKGROUND [0002] 1. Technical Field [0003] The present invention relates to a liquid ejecting apparatus and a maintenance method of the liquid ejecting apparatus. [0004] 2. Related Art [0005] An ink jet printer (hereinafter referred to as a “printer”) capable of ejecting ink (liquid) droplets onto a printing medium from ejection orifices (nozzles) of a printing head (liquid ejection head) is known as a liquid ejecting apparatus. [0006] Such a printer includes a tank for containing ink therein, and supplies the ink inside the tank to the printing head and ejects the ink from the printing head. The ink is generally made of a dispersion liquid containing solid content, such as pigment or the like, and a dispersion medium such as solvent. [0007] In a case where the printer uses the ink, in particular, if the printer is powered-off and is maintained in a disused state, the solid content contained in the ink contained in the tank is separated and settled (sunken), so that the concentration of the solid content in the ink becomes uneven. If the solid content is settled and thus the concentration of the solid content becomes uneven, when the ink is ejected by again turning the power on after the power is turned off when the printing is carried out, the solid content settled in the tank is supplied to an ink jet head side as it is, such that the nozzles of the printing head are clogged or unevenness defects are produced in the printing quality. [0008] In order to prevent such a problem, there is known a printing apparatus (printer) including two supply passages which are provided to communicate with the tank for storing (containing) the ink with the printing head, to circulate the ink between the printing head and the tank (for example, refer to JP-A-2007-331281). [0009] However, there is a concern that the circulation of the ink may cause inflow of gas from an ejection head in the above-described configuration. SUMMARY [0010] An advantage of some aspects of the invention is that it provides a liquid ejecting apparatus which can suppress inflow of gas from an ejection head at a maintenance operation. [0011] According to an aspect of the invention, there is provided a liquid ejecting apparatus comprising a liquid ejection head that ejects a liquid via nozzles; a first passage that communicates with the liquid ejection head, the first passage being configured to supply the liquid to the liquid ejection head; a second passage that communicates with the first passage in the liquid ejection head, the second passage forming, in cooperation with the first passage, a circulation passage; and a liquid driving unit provided in the circulation passage, the liquid driving unit being configured to move the liquid in the circulation passage when driven. The liquid is moved, by the driven liquid driving unit, at a first flow rate that maintains a meniscus of the liquid inside the nozzles after the liquid is moved at a second flow rate that is faster than the first flow rate. [0012] The liquid ejecting apparatus may further include the feature that movement of the liquid at the second flow rate is capable of breaking the meniscus of the liquid inside the nozzles. [0013] Preferably, the liquid ejecting apparatus further comprises a cap configured to cover an area that includes the nozzles of the liquid ejection head, where the liquid is moved at the second flow rate in a state in which the liquid ejection head is covered by the cap. [0014] Preferably, the liquid ejecting apparatus further comprises a flexible member that constitutes part of an inner wall of the circulation passage, the flexible member deforming in accordance with a change of liquid pressure in the circulation passage. [0015] The liquid ejecting apparatus preferably further comprises a valve provided in the first passage to allow and restrict flow of the liquid, which, in embodiments including the flexible member, may be in accordance with deformation of the flexible member. [0016] The liquid ejecting apparatus may further include the feature of the valve allowing the flow of the liquid in the first passage to the liquid ejection head when pressure in the first passage between the valve and the liquid ejection head decreases and reaches a predetermined pressure higher than a first pressure at which the liquid is moved at the first flow rate. [0017] Other objectives and attainments will become apparent from the following description taken in conjunction with drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0018] The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. [0019] FIG. 1 is a perspective view schematically illustrating the configuration of a printer apparatus according to an embodiment of the invention. [0020] FIG. 2 is a plan view of main parts in the vicinity of an ejection head. [0021] FIG. 3 is a plan view illustrating a nozzle orifice forming surface of an ejection head. [0022] FIG. 4 is a view illustrating the cross-sectional configuration of an ejection head. [0023] FIG. 5 is a diagram illustrating the schematic configuration of a maintenance mechanism. [0024] FIG. 6 is a block diagram illustrating the configuration of a printer apparatus. [0025] FIG. 7 is a view illustrating the operation of a printer apparatus. [0026] FIG. 8 is a view illustrating the operation of a printer apparatus. [0027] FIG. 9 is a view illustrating the operation of a printer apparatus. [0028] FIGS. 10A and 10B are perspective views schematically illustrating the configuration of a printer apparatus according to another embodiment of the invention. DESCRIPTION OF EXEMPLARY EMBODIMENTS [0029] A liquid ejecting apparatus according to an embodiment of the invention will now be described with reference to the accompanying drawings. In this instance, in the various drawings used in the following description, the scales of the various constituents of the liquid ejecting apparatus are appropriately modified in order to allow the respective constituents to have recognizable sizes. In this embodiment, an ink jet printer is exemplified as the liquid ejecting apparatus. [0030] FIG. 1 is a perspective view schematically illustrating the configuration of the ink jet printer (hereinafter, simply referred to as a printer apparatus PRT) according to an embodiment of the invention. FIG. 2 is a plan view of main parts in the vicinity of an ejection head. FIG. 3 is a plan view illustrating a nozzle orifice forming surface of the ejection head. [0031] In FIG. 1 , there is a case where a Cartesian coordinate system is set, and then a positional relationship of each component is described with reference to the Cartesian coordinate system. In such a case, a transport direction of a printing medium M is set to an X direction (horizontal direction in FIG. 1 ), a direction perpendicular to a nozzle forming region 15 of an ejection head 11 is set to a Z direction (vertical direction in FIG. 1 ), and a direction perpendicular to an X-Z plane formed by an X-axis and a Y-axis is set to a Y direction (depth direction of paper in FIG. 1 ). [0032] As shown in these drawings, the printer apparatus PRT is an apparatus capable of printing images, characters or the like on a printing medium M. Paper, plastic or the like can be used as the printing medium M. The printing apparatus PRT includes an ink ejection mechanism IJ, a transport mechanism CR, a maintenance mechanism MN, and a control device CONT. [0033] The ink ejection mechanism IJ is a unit capable of ejecting ink droplets (liquid) on the printing medium M. The ink ejection mechanism IJ includes an ejection head (liquid ejection head) 11 and an ink supply unit 12 . The ink used in this embodiment contains dye or pigment, and solvent for dissolving or dispersing it, as basic components, and uses a liquid material added with various additives, if necessary. [0034] The ejection head 11 is a head capable of ejecting ink droplets of plural colors on the printing medium M. The ejection head 11 is an ejection head of a line type having a nozzle forming region 15 along the length (maximum printing sheet width W) exceeding at least one side of the printing medium M of the maximum size which is a target of the printer apparatus PRT, as shown in FIG. 2 . The ejection head 11 is provided in such a manner that it is able to move in the Z direction. The ejection head 11 has nozzles 13 and common ink chambers 14 shown in FIG. 4 . [0035] The common ink chamber 14 is one chamber (common ink chambers 14 Y, 14 M, 14 C, and 14 K) for retaining each ink corresponding to, for example, four colors (yellow: Y, magenta: M, cyan: C, and black: K). The nozzle forming regions 15 is provided at a portion corresponding to the common ink chamber 14 of each color (nozzle forming regions 15 Y, 15 M, 15 C and 15 K). [0036] The nozzles 13 are orifice portions which are discretely installed in the nozzle forming regions 15 Y, 15 M, 15 C, and 15 K respectively of the injection head 11 to discharge the ink droplets of four colors. The plurality of nozzles 13 respectively communicate with one common ink chamber 14 . The nozzles 13 are discretely arranged in the Y direction (nozzle row L), as shown in FIG. 3 . One row or plural rows of the nozzle row L are provided in parallel with respect to the nozzle forming regions 15 Y, 15 M, 15 C, and 15 K of each color. The number of the nozzles 13 or the number of the nozzle rows L is appropriately set. The surface of the injection head 11 , in which the nozzles 13 are installed, becomes an injection surface 11 A. The injection surface 11 A is provided at the −Z side of the injection head 11 . The injection head 11 is adapted to inject the ink droplets in the −Z side. [0037] FIG. 4 is a cross-sectional view illustrating the configuration of the injection head 11 . [0038] As shown in FIG. 4 , the injection head 11 includes a head body 18 , and a liquid passage forming unit 22 which is connected to the head body 18 . The liquid passage forming unit 22 has a vibration plate 19 , a liquid passage substrate 20 , and a nozzle substrate 21 . [0039] The head body 18 is provided with a plurality of piezoelectric elements 25 , and each of the piezoelectric elements 25 is provided corresponding to each of the plurality of nozzles 13 . [0040] The liquid passage forming unit 22 has the common ink chambers 14 , an ink supply orifice 30 connected to the corresponding common ink chamber 14 , and a pressurized chamber 31 connected to the ink supply orifice 30 . The pressurized chamber 31 is provided corresponding to each nozzle 13 . Each of the pressurized chambers 31 is connected to the nozzle 13 at an end opposite to the common ink chamber 14 . [0041] The nozzle substrate 21 has a plurality of nozzles 13 formed at a predetermined interval (pitch) in a predetermined direction. An outer surface of the nozzle substrate 21 is an injection surface 11 A. [0042] According to the injection head 11 having the above-described configuration, when a driving signal is input to the piezoelectric element 25 , the piezoelectric element 25 expands or contracts. The expansion or contraction of the piezoelectric element 25 is transmitted as deformation of the vibration plate 19 . Due to the deformation of the vibration plate 19 , the volume of the pressurized chamber 31 is changed, and thus the pressure of the pressurized chamber 31 receiving the ink therein is varied. The variation in pressure causes the ink to eject from the nozzles 13 . [0043] The transport mechanism CR includes a sheet transfer roller 35 , a discharge roller 36 , and the like. The sheet transfer roller 35 and the discharge roller 36 are adapted to be rotated by a motor mechanism (not illustrated). The transport mechanism CR transports the printing medium M along a transport path MR in connection with ejection operation of the ink droplets by the ink ejection mechanism IJ. [0044] Returning to FIG. 1 , the ink supply section (liquid storage unit) 12 is placed at one side of the ink ejection mechanism IJ, and is connected to each of the common ink chambers 14 Y, 14 M, 14 C, and 14 K of the ejection head 11 . The ink supply unit 12 has ink tanks 12 Y, 12 M, 12 C, and 12 K for storing the ink of four colors. [0045] The ink supply unit 12 is connected to the ejection head 11 via a first supply tube SR 1 and a second supply tube SR 2 . The first supply tube SR 1 is a passage (first supply passage) for supplying the ink from the ink supply unit 12 to the ejection head 11 . The first supply tube SR 1 is provided with a valve unit VU. The second supply tube SR 2 is a passage (second supply passage) communicating with the ink supply unit 12 and the ejection head 11 . The second supply tube SR 2 is provided with a supply pump (liquid driving unit) RP. A flow of the ink supplied from the ink supply unit 12 to the ejection head 11 and a flow of the ink supplied from the ejection head 11 to the ink supply unit 12 are produced in accordance with a driving direction of the supply pump RP. [0046] FIG. 5 is a cross-sectional view schematically illustrating the configuration of the valve unit VU. [0047] An ink receiving chamber RM is formed in a receiving chamber forming member 50 . The receiving chamber forming member 50 has a partition portion 51 at a center portion of the horizontal direction in the drawing. The ink receiving chamber RM is divided into a first chamber (recessed portion) R 1 and a second chamber R 2 by the partition portion 51 . The partition portion 51 is formed with a communication portion 52 . The first chamber R 1 of the ink receiving chamber RM is connected to the ink supply unit 12 via the first supply tube SR 1 . The second chamber R 2 is connected to the ejection head 11 via the first supply tube SR 1 . The first chamber R 1 and the second chamber R 2 communicate with each other via the communication portion 52 . In this way, the path from the ink supply unit 12 to the ejection head 11 is communicated in the order of the ink supply unit 12 , the first supply tube SR 1 (ink supply unit 12 side), the first chamber R 1 , the communication portion 52 , the second chamber R 2 , the first supply tube SR 1 (injection head 11 side) and the ejection head 11 . [0048] A portion (a left end in the drawing), which is different from the partition portion 51 , of the wall portion enclosing the first chamber R 1 of the receiving chamber forming member 50 is formed with an opening. The opening is formed so as to communicate with the exterior of the first chamber R 1 and the ink receiving chamber RM. A flexible member F is attached to the opening, and the opening is constantly closed by the flexible member F. [0049] The valve VB is formed to extend the first chamber R 1 and the second chamber R 2 . The valve VB has a plate-shaped portion V 1 , a flange portion V 2 , and a shaft portion V 3 . The plate-shaped portion V 1 is adhered to the flexible member F. The flange portion V 2 is provided in the second chamber R 2 , and the flange portion V 2 is provided in the second chamber R 2 . The flange portion V 2 is formed with a sealing portion V 4 for closing the communication portion 52 . The communication portion 52 is interrupted by bringing the sealing portion V 4 into contact with the partition portion 51 . [0050] The shaft portion V 3 is placed to penetrate through the communication portion 52 . The plate-shaped portion V 1 and the flange portion V 2 are connected to each other by the shaft portion V 3 . The valve VB is configured in such a way that, as the flexible member F is bent in the direction to decrease the internal volume of the ink receiving chamber RM, the sealing portion V 4 is spaced apart from the partition portion 51 to open the communication portion 52 . [0051] A biasing mechanism SP is interposed between the plate-shaped portion V 1 and the partition portion 51 . A spring member or the like is preferably used as the biasing mechanism SP. The biasing mechanism SP bends the flexible member F in a direction of increasing an internal volume of the first chamber R 1 , thereby biasing the plate-shaped portion V 1 toward a left side (direction spaced apart from the partition portion 51 ) of the drawing. The biasing force of the biasing mechanism SP is set in such a way that when the ink receiving chamber RM is lower than the predetermined pressure, the sealing portion V 4 opens the communication portion 52 , and for the rest, the sealing portion V 4 interrupts the communication portion 52 . [0052] In the case where the ink is ejected from the ejection head 11 , since the communication portion 52 is interrupted by the sealing portion V 4 , negative pressure is generated in the liquid passage from the first chamber R 1 to the ejection head 11 . If the force of bending the flexible member F due to the negative pressure is stronger than the biasing force of the biasing mechanism SP, the flexible member F is bent and thus the communication portion 52 is opened. [0053] Since the first chamber R 1 communicates with the ejection head 11 and the second chamber R 2 communicates with the ink supply unit 12 , the ink is supplied from the second chamber R 2 to the first chamber R 1 side via the communication portion 52 . If the negative pressure from the first chamber R 1 to the ejection head 11 by the supply of the ink is decreased, the biasing force of the biasing mechanism SP is higher than the corresponding negative pressure, the communication portion 52 is interrupted by the sealing portion V 4 . [0054] In this way, since the negative pressure is generated in the passage from the first chamber R 1 to the ejection head 11 , the valve unit VU has an action of adjusting an ink meniscus of the nozzles, and an action of a check valve (one-way valve) through which the ink flows only in the direction from the second chamber R 2 to the first chamber R 1 . [0055] Returning to FIG. 1 , the supply pump RP adjusts a flow direction and flow velocity (supply speed) of the ink flowing in the second supply tube SR 2 . According to the flow direction of the ink, the ink can be switched and supplied in either of a forward direction from the ejection head 11 to the ink supply unit 12 or a backward direction from the ink supply unit 12 to the ejection head 11 . In this instance, when the flow of the ink in the second supply tube SR 2 is the forward direction, the flow of the ink in the first supply tube SR 1 is set to a flow direction from the ink supply unit 12 to the ejection head 11 . In addition, when the flow velocity is adjusted, the supply pump RP is adapted to vary the flow velocity of at least ink supplied in the forward direction, depending upon whether or not the ejection surface 11 A is covered by a cap member 42 which will be described below. In this instance, the variation in flow velocity is controlled by the control device CONT. [0056] The maintenance mechanism MN performs a maintenance for the ejection head 11 . The maintenance mechanism MN includes the cap member 42 and an actuation mechanism ACT. The cap member 42 is formed in the shape of a plate by using a material, for example, rubber, elastomer or the like. The cap member 42 has a close contact surface 42 a which is brought into close contact with the ejection surface 11 A of the ejection head 11 . The close contact surface 42 a is provided to be opposite to the ejection surface 11 A of the ejection head 11 . The cap member 42 is formed to have a dimension large enough to be able to cover at least a range, in which the nozzle NZ is formed, of the ejection surface 11 A. For this reason, the cap member 42 is formed so as to bring it into close contact with and over the surface, in which the nozzle NZ is formed, of the ejection surface 11 A, so that the surface is covered. [0057] In this embodiment, an absorbing member (not illustrated) for receiving the ink ejected from each nozzle 13 of the ejection head 11 is provided separately from the cap member 42 . The absorbing member is able to be placed on a flying path in a state where the cap member 42 is retracted from the flying path of the ink ejected from each nozzle 13 . In this instance, the absorbing member placed on the flying path of the ink receives the ink from the head. [0058] The actuation mechanism ACT moves the cap member 42 between the ejection head 11 and the actuation mechanism. An actuator such as cam mechanism, a motor mechanism, air cylinder mechanism or the like may be used as the actuation mechanism ACT. Of course, other actuator can be used. [0059] FIG. 6 is a block diagram illustrating the electrical configuration of the printer apparatus PRT. [0060] The printer apparatus PRT according to the embodiment includes the control device CONT for controlling the whole operation. The control device CONT is connected to an input device 59 for inputting various information about the operation of the printer apparatus PRT, and a memory device 60 for storing various information about the operation of the printer apparatus PRT. [0061] The control device CONT is connected to each section of the printer apparatus PRT, such as the ink ejection mechanism IJ, the transport mechanism CR, the maintenance mechanism MN, or the like. The printer apparatus PRT includes a driving signal generator 62 for generating a driving signal which is input to the driving unit having the piezoelectric element 25 . The driving signal generator 62 is connected to the control device CONT. [0062] The driving signal generator 62 is input with data indicative of a variation in voltage value of a discharge pulse which is input to the piezoelectric element 25 of the ejection head 11 , and a timing signal defining a timing changing a voltage of the discharge pulse. The driving signal generator 62 generates a driving signal, such as discharge pulse, based on the input data and the timing signal. [0063] Next, the operation of the printer apparatus PRT including the above-described configuration will be described. [0064] In a case where the ejection head 11 carries out the printing operation, the control device CONT places the printing medium M on a support surface (not illustrated) by using the transport mechanism CR. After the printing medium M is placed, the control device CONT inputs the driving signal to the piezoelectric element 25 from the driving signal generator 62 based on the image data of an image to be printed. [0065] If the driving signal is input to the piezoelectric element 25 , the piezoelectric element 25 is expanded or contracted to eject the ink from the nozzles 13 . The desired image is formed on the printing medium M by the ink ejected from the nozzles 13 . [0066] A capping operation is carried out as the maintenance operation of the ejection head 11 . In the case of carrying out the capping operation, the control device CONT presses the cap member 42 towards the ejection head 11 side by using the driving mechanism ACT. The gap between the cap member 42 and the ejection head 11 is sealed by the operation. [0067] If the power source of the printer apparatus PRT is turned off and thus is maintained in a disused state, a solid content contained in the ink which is received in the ink supply unit 12 is separated and settled (sunken), so that the concentration of the solid content in the ink becomes uneven. If the solid content is settled and thus the concentration of the solid content becomes uneven, when the ink is ejected to carry out the printing by again turning the power on after the power is turned off, the settled solid content is supplied to the ejection head 11 side as it is. As a result, there is problem in that the nozzles of the ejection head 11 may be clogged or unevenness may occur in the printing quality. [0068] Accordingly, in order to prevent such a problem, the ink should be circulated between the ink supply unit 12 and the ejection head 11 . The control device CONT operates the supply pump RP to cause the ink in the second supply tube SR 2 to flow in the forward direction (direction from the ejection head 11 to the ink supply unit 12 ) or the backward direction (direction from the ink supply unit 12 to the ejection head 11 ). [0069] As a specific example, the control device CONT operates the supply pump RP to cause the ink to flow in the forward direction in the state where the ejection surface 11 A of the ejection head 11 is covered by the cap member 42 , as shown in FIG. 7 . The negative pressure is generated in the first chamber R 1 by the operation, and thus the sealing portion V 4 of the valve VB opens the communication portion 52 , and the valve unit VU comes to be is in the opened state, so that the passage is communicated from the ink supply unit 12 to the ejection head 11 . For this reason, the ink is supplied from the ink supply unit 12 to the ejection head 11 via the first supply tube SR 1 . At this time, although the negative pressure is generated in the ejection head 11 which is positioned at the upstream side of the supply pump RP, since the ejection surface 11 A is covered by the cap member 42 , the air does not flow in the nozzles 13 , so that the ink does not leak from the nozzles 13 . For this reason, it is easy to stir the settled solid content components by increasing the flow velocity (supply speed) of the ink. Since the operation is carried out in the state in which the power source of the printer device PRT is turned on, it is possible to shorten the time needed to supply the ink in a short time. [0070] In addition, as another aspect, the control device CONT may operate the supply pump RP so that the ink flows in the forward direction, as shown in FIG. 8 , in the state where the ejection surface 11 A of the ejection head 11 is not covered by the cap member 42 . In this instance, since the ink does not flow in from the nozzles 13 , the control device CONT operates the supply pump RP so that the pressure P I of the ink becomes a pressure maintaining the meniscus of the ink in the corresponding nozzle 13 . [0071] In a case where the pressure P O in the first supply tube SR 1 which is required to allow the ink to pass the valve unit VU from the ink supply unit 12 is −100 Pa, and the pressure P M of maintaining the meniscus in the nozzle 13 is −200 Pa, the supply speed of the ink by the supply pump RP is adjusted in a liquid driving process so that the pressure P I of the ink is set to a value (for example, −150 Pa or the like) therebetween. In this instance, if a case where the flow pressure P I of the ink is higher than the pressure P O , since the valve unit VU is in the closed state, the ink does not flow. In addition, in a case where the pressure P M of maintaining the meniscus in the nozzle 13 is less than −200 Pa, the flow pressure P I of the ink does not maintain the meniscus of the ink in the nozzle 13 , such that the discharge amount of the ink cannot be accurately controlled. Accordingly, it is preferable that P M <P I <P O . The above-mentioned values are merely one example, and the invention is not limited thereto. [0072] The operation of supplying the ink according to the embodiment shown in FIG. 8 can be carried out for the period in which the power source of the printer apparatus PRT is turned on, and is carried out for the period different from the period in which the ink is ejected onto the printing medium M by the ejection head 11 . In addition, it is preferable that after the settlement of the ink is solved by performing the operation of supplying the ink according to the embodiment shown in FIG. 7 , the operation of supplying the ink according to the embodiment shown in FIG. 8 is carried out at the flow velocity not settling the ink. [0073] In addition, as another aspect, the control device CONT may drive the supply pump RP so that the ink flows in the backward direction, as shown in FIG. 9 , in the state where the ejection surface 11 A of the ejection head 11 is not covered by the cap member 42 . In this instance, since the first chamber R 1 is pressurized and the flexible member F is bent in the direction of increasing the volume of the first chamber R 1 , the communication portion 52 is interrupted by the sealing portion V 4 . For this reason, in the state where the valve unit VU is in the closed state, the flow of the ink does not occur in the first supply tube SR 1 . [0074] Further, the ink flowing into the ejection head 11 via the second supply tube SR 2 is discharged outwardly to the ejection head 11 from the nozzle 13 . Here, since the cap member 42 is retracted from the ejection path of the ejection head 11 , the discharged ink is received by the absorbing member (not illustrated) or the like. The flushing (cleaning) operation can be performed by the ink supplied from the second supply tube SR 2 side. [0075] When the printing is carried out by using the ejection head 11 , there is a case where alien substances are adhered to the nozzles 13 or the ink with increased viscosity is adhered to the nozzles 13 . In this instance, at least one of the nozzles 13 provided in the ejection head 11 is clogged, thereby leading to a defective ejection state. The operation of supplying the sink, as shown in FIG. 9 , can be performed for the purpose of addressing the above-described defective ejection state of the nozzles 13 . Since the nozzles 13 with the defective ejection state can be cleaned through the ink supply operation, a suction mechanism for the cap member 42 is not necessary. Of course, the operation of supplying the ink may be performed for other purposes or in other cases. [0076] As described above, according to this embodiment, since the printer apparatus includes the first supply tube SR 1 for supplying the ink from the ink supply unit 12 to the ejection head 11 , and the second supply tube SR 2 which is provided separately from the first supply tube SR 1 , and communicates with the ejection head 11 and the ink supply unit 12 , in which the ink is supplied in the forward direction by the supply pump RP provided in the second supply tube SR 2 in the state where the cap member 42 comes into close contact with the ejection head 11 , the ink is supplied in the state where the nozzles 13 are sealed. For this reason, it is possible to prevent inflow of the air from the nozzles at an interval of the ink supply. In addition, it is possible to prevent the ink from leaking from the nozzles. [0077] It should be noted that the technical scope of the invention is not limited to the above-described embodiment, and proper modifications can be undergone within the scope without deviating from the aspects of the invention. [0078] For example, in the above-described embodiment, a configuration is described in which the invention is applied to the printer employing the line type head. However, the invention is not limited thereto, and may be applied to the printer apparatus PRT 2 employing a serial type head, as shown in FIG. 10A . [0079] In this instance, the configuration of the printer apparatus PRT 2 will be described in brief. The printer apparatus PRT 2 includes a printer body 105 , and a carriage 104 on which a sub tank 102 and an ejection head 103 are mounted. The printer body 105 is provided with a carriage moving mechanism 154 for reciprocating the carriage 104 , a capping device 150 for use in the cleaning operation or the like which suctions the ink with increased viscosity from each nozzle of the ejection head 103 , and an ink cartridge 106 for storing the ink which is supplied to the ejection head 103 via an ink supply tube 134 . The printer body 105 is provided with a sheet transport mechanism (not illustrated) for transporting a printing sheet. The sheet transport mechanism includes a sheet transport motor (not illustrated) or a sheet transport roller (not illustrated) which is rotated by the sheet transport motor, and is adapted to sequentially feed the printing sheets onto a platen 113 in connection with recording (printing) operation. [0080] The carriage moving mechanism 154 includes a guide shaft 108 installed in a width direction of the printer body 105 , a motor 109 , a driving pulley 110 which is connected to a rotation shaft of the motor 109 and is rotated by the motor 109 , an idle pulley 111 installed opposite to the driving pulley 110 in the width direction of the printer body 105 , and a timing belt 112 suspended between the driving pulley 110 and the idle pulley 111 and is connected to the carriage 104 . The carriage moving mechanism 154 drives the motor 109 , so that the carriage 104 reciprocates along the guide shaft 108 in a main scanning direction. [0081] The capping device 150 is placed at a home position in the printer body 105 . The home position is an end area more outside than a printing region in the moving region of the carriage 104 , and is set to a place in which the carriage 104 is positioned in a case where a power source is turned off or the recording is not performed for a long time. The printer apparatus PRT 2 includes the configuration as described above. [0082] In addition, although the configuration in which the ejection head 11 is directly connected to the ink supply unit 12 is exemplified in this embodiment, the invention is not limited thereto. As shown in FIGS. 10A and 10B , a configuration may be provided, in which the ink cartridge (main tank) 106 and the sub tank 102 are provided as a tank for storing the ink, and the ink is circulated between the sub tank 102 and the ejection head 103 respective. In this instance, the invention can be applied by installing the first supply tube SR 1 and the second supply tube SR 2 as a flow passage for circulating the ink, placing the valve unit VU in the first supply tube SR 1 , and placing the supply pump RP in the second supply tube SR 2 . [0083] In the above description, the ink jet printer and ink cartridge are employed, but a liquid ejecting apparatus for ejecting or discharging a liquid other than ink, and a liquid container for receiving the liquid may be employed. It may be applied to various liquid ejecting apparatuses including a liquid ejection head for discharging a minute number of liquid droplets. In this instance, the expression “liquid droplets” means the liquid ejected from the liquid ejecting apparatus, and includes a liquid having a particle shape, a tear shape, or a linear shape. Further, here, the liquid may be a material which can be ejected from the liquid ejecting apparatus. [0084] For example, a liquid-state material may be used, and includes a liquid-state material such as sol or gel water having a high or low viscosity, a liquid-state material such as an inorganic solvent, an organic solvent, a liquid, a liquid-state resin, or liquid-state metal (metallic melt), and a material in which particles of a functional material having a solid material such as pigment or metal particles is dissolved, dispersed, or mixed with solvent in addition to a liquid, as one state of a substance. In addition, ink described in the embodiments may be exemplified as a typical example of the liquid, liquid crystal and the like. Here, the ink indicates general water-based ink, oil-based ink, gel ink, or hot-melt ink which contains various liquid compositions. [0085] As a detailed example of the liquid ejecting apparatus, for example, a liquid crystal display, an EL (electro-luminance) display, a plane-emission display, a liquid ejecting apparatus for ejecting a liquid containing dispersed or melted materials such as an electrode material or a color material used to manufacture a color filter, a liquid ejecting apparatus for ejecting a biological organic material used to manufacture a biochip, a liquid ejecting apparatus for ejecting a liquid as a sample used as a precision pipette, a printing apparatus, or a micro dispenser may be used. [0086] In addition, a liquid ejecting apparatus for ejecting lubricant from a pinpoint to a precision machine such as a watch or a camera, a liquid ejecting apparatus for ejecting a transparent resin liquid such as a UV-curing resin onto a substrate in order to form a minute hemispherical lens used for an optical transmission element or the like, or a liquid ejecting apparatus for ejecting an etching liquid such as an acid liquid or an alkali liquid in order to perform etching on a substrate or the like may be adopted. The invention may be applied to at least one kind of the above-described ejection apparatuses and the liquid container.	A liquid ejecting apparatus comprising a liquid ejection head that ejects a liquid via nozzles; a first passage that communicates with the liquid ejection head, the first passage being configured to supply the liquid to the liquid ejection head; a second passage that communicates with the first passage in the liquid ejection head, the second passage forming, in cooperation with the first passage, a circulation passage; and a liquid driving unit provided in the circulation passage, the liquid driving unit being configured to move the liquid in the circulation passage when driven. The liquid is moved, by the driven liquid driving unit, at a first flow rate that maintains a meniscus of the liquid inside the nozzles after the liquid is moved at a second flow rate that is faster than the first flow rate.	1
FIELD OF THE INVENTION This invention relates to a method and apparatus for displaying angiographic data in a topographic format, and more specifically to a method and apparatus for displaying an image based on Ultrasound Anglo data which enhances the visibility of blood vessel boundaries. BACKGROUND OF THE INVENTION Ultrasound Angio data represents the amount of blood flowing in a scanned region of interest ("ROI"). The greater the number of reflectors in a particular section of the ROI, the larger the amplitude of the Doppler signal received from the particular section. For example, FIG. 3a illustrates the blood vessels near the edge of a kidney. The Ultrasound Angio signal generated by scanning the blood vessels across line 5--5 is illustrated in FIG. 3b, where the horizontal axis represents lateral position and the vertical axis represents the amplitude of the Angio data. As expected, the amplitude of the Angio region 8 for a larger vessel 10 is relatively large, and the Angio region 14 for smaller vessels 12 is relatively small. In the past, blood flow displays have been produced by mapping the Angio data to a color hue. For example, in a typical image, sections with higher Angio values may be displayed with brighter colors and sections with lower Angio values may be displayed with dimmer colors. One problem with displaying and interpreting Ultrasound Angio data in this manner is that small vessels are difficult to detect. The large vessels with high amplitude signals dominate the display, while the small vessels with lower amplitudes can fade into the background. Specifically, the large, high amplitude vessels will be displayed in the brightest colors and will therefore be easiest to see, while the smallest vessels will be dim and difficult to detect. In light of the foregoing, it is clearly desirable to provide an apparatus and method for displaying blood flow which increases the visibility of smaller vessels. Further, it is clearly desirable to provide an apparatus and method for increasing the visibility of edges in an image illustrating blood flow. SUMMARY AND OBJECTS OF THE INVENTION According to one aspect of the invention, an apparatus for generating an image that represents a flow of a substance in a scanned area is provided. The scanned area may be, for example, an Ultrasound Angio region of interest. The image has a plurality of image subregions. The apparatus includes a scanner, a processing circuit and a display unit. The scanner scans the region of interest to produce a plurality of scanned values. The scanner may be, for example, an ultrasound Angio scanner and the plurality of scanned values may be ultrasound Angio data. The scanned value for each scanned section has an amplitude which represents the flow of the substance in the scanned section. The processing circuit may be, for example, a digital processor or an analog circuit. The processing circuit receives the plurality of scanned values from the scanner. The processing circuit determines a color index for each image subregion and develops a second set of indices based on spatial derivatives derived from the first set of indices. The display unit receives these new indices and displays an RGB color value corresponding to each index. The image displayed by the apparatus displays blood vessels as edge-enhanced regions lending the appearance of three dimensions. According to another aspect of the invention, a method for determining color hues for a plurality of image subregions in an image is provided. The scanned area may be, for example, an Ultrasound Angio region of interest and the substance may be blood. The image is an image of a scanned area which has a plurality of scanned sections. According to the method, a correlation is established between a plurality of color values and a range of composite values. This may be performed, for example, by mapping gray scale shades to the range of composite values. For each given image subregion, a selected set of scanned sections, including a first scanned section, is selected. This may be performed, for example, by selecting the first scanned section and one or more scanned sections laterally aligned with the first scanned section. Angio values that represent the flow of blood in the selected set of scanned sections is received. The Angio values include a first value that represents the flow of the substance in the first scanned section. A derivative value is generated based on the Angio values. The derivative value is a spatial derivative of the Angio values. A composite value is generated based on the derivative value. This may be performed, for example, by adding a fraction of the first value to the derivative value. More specifically, this may be performed, by multiplying the first value by a first coefficient to generate a first product, multiplying the derivative value by a second coefficient to generate a second product, and adding the first product and the second product to a predetermined constant. In addition, a bias value is added to the aforementioned sum. A color value for each region is selected based on the composite value according to the established RGB lookup table. According to one aspect of the invention, the image appears to display three dimensional ridges illuminated by a light source. Optionally, the method includes a step in which a user selects an orientation of the light source. BRIEF DESCRIPTION OF THE DRAWINGS The invention may best be understood by referring to the following description and accompanying drawings which illustrate the invention. In the drawings: FIG. 1 is a block diagram of a device for displaying images representing the flow of blood in an Ultrasound Angio region of interest according to one embodiment of the invention; FIG. 2 is a block diagram which illustrates the relationship between a scanned area and a displayed image according to an embodiment of the invention; FIG. 3a illustrates blood vessels in an exemplary scanned area; FIG. 3b is a graph illustrating the amplitude of Angio values produced by scanning the blood vessels of FIG. 3a; FIG. 3c is a graph illustrating the amplitude of derivative values generated based on the Angio values of FIG. 3b; FIG. 3d is a graph illustrating the amplitude of composite values generated based on the Angio values of FIG. 3b and the derivative values of FIG. 3c; and FIG. 4 is a flow chart of a method for generating color values for a scanned image according to an embodiment of the present invention. DETAILED DESCRIPTION FIG. 1 illustrates a functional block diagram of an imaging device 100 for displaying ultrasound Angio images according to one embodiment of the present invention. As explained above, Angio images represent the flow of blood in a scanned region of interest. However, while embodiments of the present invention shall be described with respect to blood flow in a scanned region of interest, imaging device 100 is not limited to any specific type of flow measurements. Thus, imaging device 100 may alternatively display images of the flow of any substance in any type scanned area. Imaging device 100 generally includes a scanner 102, a user input device 104, a storage device 105, a processing circuit 106, and a display unit 108. Scanner 102 is preferably an ultrasound Angio scanner. Scanner 102 scans a region of the body and produces signals representative of the amount of blood flow in the region of interest. The processing circuit 106 is connected to the scanner 102. The processing circuit 106 may be, for example, a general purpose digital processor, a digital signal processor, or an analog circuit. The processing circuit 106 receives the signals from the scanner 102 and generates a plurality of color values based on the signals. As shall now be explained, processing circuit 106 is configured to generate color values in which values representing smaller vessels have approximately the same amplitude as those representing larger vessels. As mentioned above, when Angio data is mapped directly to a color value to produce an image, the vessels represented by smaller amplitude data are difficult to discern. Processing circuit 106 overcomes this obstacle by processing the raw Angio data to produce color values in which smaller vessels and larger vessels are represented by values of similar amplitude. Specifically, processing circuit 106 equalizes the amplitude of the larger and smaller vessels by taking the spatial derivative of the Angio data. For example, assume that the Angio amplitude from a vessel is roughly proportional to the vessel's width. If the functional form of the response of one vessel is f(x), then a vessel that is larger by a factor "a" would have a spatial Angio response of a[f(x/a)]. The derivative of the smaller vessel would be f(x), while the derivative of the larger vessel is f(x/a). Consequently, the derivative of the larger vessel is still longer spatially than the small vessel, but they both have the same magnitude. The spatial derivative of the Angio signal illustrated in FIG. 3b is shown in FIG. 3c. Specifically, the spatial derivative of Angio region 8 results in curve 300, and the spatial derivative of Angio regions 14 results in curves 302. As is evident, the geometric sizes of the Angio regions are preserved in the derivative operation, but the amplitudes of the data corresponding to the larger and smaller vessels have been equalized. According to one embodiment, a blood flow image is produced by mapping the spatial derivative values to colors or shades of gray. In such an image, the visibility of the smaller vessels is significantly enhanced. However, one problem with an image colored solely based on the spatial derivative values is that zero is no longer the minimum possible amplitude value. Therefore, a bias is preferably added to the derivative values before a color or grayscale value is assigned. Another disadvantage of using only the derivative values to generate an image is that the derivative values corresponding to vessels which flow perpendicular to the direction of the spatial derivative are much greater than the derivative values corresponding to vessels with the same flow that are not perpendicular to the direction of the spatial derivative. For example, a large vessel with a high but constant flow that runs parallel to the direction of the spatial derivative may have no corresponding derivative curve at all. Therefore, the vessel may not appear in an image based solely on the derivative values. Preferably, evidence of such parallel vessels is retained by adding back to the derivative values a fraction of the original Angio values. FIG. 3d illustrates a graph of the curves created by adding a bias value and a fraction of the Angio regions of FIG. 3b to the derivative curves of FIG. 3c. The processing required to transform the derivative data to produce the values shown in FIG. 3d may be implemented using a constant plus a two tap FIR filter. The exact values of the parameters are preferably based on the range and spacing of the original Angio data. For example, assume that the amplitudes of the original Angio data range from 0 to 255 and that the resolution of the scan is such that the largest change from one Angio value to its nearest neighbor is usually less than 1/6 of this range. Under these conditions, a composite value for each scanned section may be generated by summing a bias constant of 128 with three times the derivative value corresponding to the section and half of the original Angio value corresponding to the section. The resulting composite values will generally fall within the original range of 0 to 255. The mechanism used by processing circuit 106 to generate the plurality of color values based on the plurality of composite values shall be described in greater detail below. The display unit 108 is operatively coupled to the processing circuit 106. The display unit 108 generally represents one or more devices capable of displaying an image with a varying color characteristic. The color characteristic which varies is preferably brightness. Therefore, the display unit need not be capable of rendering color images. Display unit 108 may therefore include a grayscale or color printer, or a grayscale or color video display device. The display unit 108 receives the color values from the processing circuit 106 and generates an image of the scanned area which is colored based on the color values. It has been discovered that images representing three-dimensional topographic maps are produced when brighter colors are assigned to image subregions corresponding to higher color values and darker colors are assigned to image subregions corresponding to lower color values. Specifically, blood flows faster in the center of a blood vessel. Therefore, the Angio values representing a blood vessel will increase as the scan approaches the center of the vessel and decrease as the scan moves away from the center of the vessel. Consequently, the derivative values will be positive on one side of a blood vessel, zero at the center of a blood vessel, and negative on the other side of the blood vessel. This characteristic of the derivative values is retained in the color values. Thus, when an image is colored based on the color values, blood vessels appear as ridges having one bright side and one dark side. The bright side appears as if illuminated by a light source, while the dark side appears to be in shadow. Referring now to FIG. 2, it illustrates the relationship between a scanned region of interest 200 and an image 204 representing the scanned area. When scanner 102 scans area 200, the resulting signals produce a matrix of Angio values 206 representing the blood flow within area 200. Each Angio value in the Angio value matrix 206 has an amplitude representing the flow of blood within a specific section of area 200. For example, the amplitude of an Angio value 208 corresponds to the flow of blood within a first section 210, and the amplitude of an Angio value 212 represents the flow of blood within a second section 214. The size of each section depends on the resolution of scanner 102. The processing circuit 106 processes the values contained in Angio value matrix 206 to generate a color characteristic matrix 216. Each color value in the color characteristic matrix corresponds to a section of area 200. For example, a color value 218 may correspond to section 210, and a color value 220 may correspond to section 214. As explained above, the color values are based in part on the spatial derivative of the Angio values. Display unit 108 generates image 204 based on the values contained in color characteristic matrix 216. Specifically, the image 204 generated by display unit 108 has a plurality of image subregions. Depending on the resolution of the image 204 and the resolution of scanner 102, each image subregion may correspond, for example, to one or more pixels on a video display device. Each image subregion has a corresponding color value in color characteristic matrix 216. Display unit 108 renders each image subregion with the color characteristic represented by its corresponding color value. Each image subregion of image 204 represents a section of area 200. For example, color value 218 may correspond to a first image subregion 222, and color value 220 may correspond to a second image subregion 224. Since color value 218 corresponds to section 210, image subregion 222 represents section 210. Likewise, since color value 220 corresponds to section 214, image subregion 224 represents section 214. Referring again to FIG. 1, processing circuit 106 shall now be described in greater detail. The processing circuit 106 includes an input circuit 110, a selecting circuit 112, a derivative circuit 114, a composite value generation circuit 116 and a mapping circuit 118. The input circuit 110 is operatively coupled to the scanner 102 and receives the plurality of Angio values. Input circuit 110 is a mechanism for storing the information from scanner 102. For example, input circuit 110 may be random access memory. To determine the color value for a given image subregion, the selecting circuit 112 selects certain Angio values from the Angio value matrix 206. For example, to determine the color value 220 for the image subregion 224, selecting circuit 112 may select Angio data value 208 and Angio data value 212. The selected Angio values represent the flow of the blood in the scanned sections corresponding to the Angio values. For example, Angio value 208 represents blood flow in section 210 and Angio value 212 represents blood flow in section 214. Preferably, the Angio values selected by selecting circuit 112 to determine a color value for a given image subregion include the Angio value of the scanned section which corresponds to the given image subregion (the "corresponding section"). The Angio value representing the flow of blood in the corresponding section is referred to herein as the corresponding Anglo value. The scanned section corresponding to image subregion 224 is section 214. Therefore, the Angio value 212 which represents section 214 is selected by selecting circuit 112. In addition, selecting circuit 112 also selects the Angio values of one or more scanned sections adjacent to the corresponding section. For example, selecting circuit 112 may select the Angio value 208 which represents section 210, which is adjacent to section 214. The derivative circuit 114 is coupled to the selecting circuit 112. The derivative circuit 114 receives the selected Angio values from the selecting circuit 112 and generates a spatial derivative value based on the selected Angio values. In the present example, the selected Angio values are Angio values 208 and 212. Therefore, the spatial derivative of these values will simply be the difference between Angio value 208 and Angio value 212. The composite value generation circuit 116 is operatively coupled to the derivative circuit 114. The composite value generation circuit 116 receives spatial derivative values from the derivative circuit 114, and the corresponding Angio value from the selecting circuit 112 from each region and generates a composite value within the range of composite values based on these inputs, a constant bias value, and two coefficients. Preferably, the composite value generation circuit 116 includes two multiplier units 122 and 123. The multiplier unit 122 multiplies the corresponding Angio value by a first coefficient to generate a first product. The multiplier unit 123 multiplies the spatial derivative value by a second coefficient to generate a second product. As described above, the first coefficient may be 0.5 and the second coefficient may be 3.0. The composite value generation circuit 116 further includes an adding unit 120 for summing the first product, the second product and a predetermined constant. As explained above, the predetermined constant is a bias value used to minimize the likelihood that the resulting color value will be negative. The first and second coefficients and the bias value may be initially stored on storage device 105. Storage device 105 may be any device for storing information. For example, storage device may be a magnetic storage device, an optical storage device, random access memory or read only memory. Processing circuit 106 retrieves the coefficient and bias values from storage device 105 prior to performing the calculations described above. The mapping circuit 118 is operatively coupled to the composite value generation circuit 116 and the display unit. The mapping circuit 118 receives each composite value from the composite value generation circuit 116. The mapping circuit 118 maps each composite value to a color value responsive to a predetermined correlation. For example, the color characteristic may be brightness. The predetermined correlation may therefore be a mapping of the composite values to shades of gray, such that the higher the composite value, the lighter the corresponding shade of gray. An image based on color values generated as described above depicts each vessel as a three dimensional ridge illuminated by a light source. The three dimensional appearance is due to the fact that each "vessel ridge" has a light side and a dark side. By reversing the direction in which the spatial derivative is taken, the shading of the ridges will be reversed (i.e. the light side will become dark and the dark side will become light). To a viewer, this has the affect of changing the orientation of the hypothetical light source which is illuminating the ridges. The spatial derivative operation may also be performed on vertically adjacent Angio values to produce an image which appears to be illuminated by a light source at the top of the image or at the bottom of the image. Likewise, the spatial derivative operation may be performed on diagonally adjacent Angio values to produce an image which appears to be illuminated by a light source in a comer of the image. Preferably, a user may operate user input device 104 to select the desired orientation of the hypothetical light source which illuminates the "vessel ridges" displayed in the image. Based on input from user input device 104, selecting circuit 112 determines the selection criteria for selecting the Angio values to generate derivative values. If the user desires the ridges to be illuminated from the left, the spatial derivative is taken from left to right. To take the spatial derivative from left to right, selecting circuit 112 selects the corresponding Angio value and an Angio value adjacent to and to the left of the corresponding Angio value. For example, to determine the spatial derivative corresponding to image subregion 224, selecting circuit 112 may select Angio value 2 12 (the corresponding Angio value) and Angio value 208 (the Angio value to the left of the corresponding Angio value). Derivative circuit 114 generates a derivative value based on the Angio values by subtracting the left Angio value from the right Angio value. Similarly, if the user desires the ridges to be illuminated from the upper left, the spatial derivative is taken diagonally from upper left to lower fight. To take the spatial derivative from upper left to lower fight, selecting circuit 112 selects the corresponding Anglo value and an Angio value adjacent to and to the upper left of the corresponding Angio value. For example, to determine the spatial derivative corresponding to an image subregion 230, selecting circuit 112 may select an Angio value 232 (the corresponding Angio value) and Angio value 208 (the Angio value to the upper left of the corresponding Angio value). Derivative circuit 114 generates a derivative value based on the Angio values by subtracting the upper left Angio value from the lower right Angio value. Referring now to FIG. 4, it illustrates the steps for determining color characteristics for the plurality of image subregions in image 204. At step 400, a correlation is established between a range of composite values and a plurality of color values. This may be performed, for example, by mapping the range of composite values to gray scale brightness. The higher the composite value, the lighter the corresponding shade of gray. Conversely, the lower the composite value, the darker the corresponding shade of gray. Steps 402 to 412 are performed for each image subregion in the image 204. At step 402 an image subregion for which a color value has not yet been determined is selected. For the purposes of this example, it shall be assumed that image subregion 224 is initially selected. At step 404, a set of scanned sections, including the scanned section corresponding to the selected image subregion, is selected. Preferably the set of scanned section includes one or more scanned sections adjacent to the corresponding scanned sections. In the present example, the selected image subregion is image subregion 224. The scanned section corresponding to image subregion 224 is scanned section 214. Therefore, scanned section 214 and scanned section 210, which is adjacent to section 214, are selected. At step 406, the Angio values corresponding to the selected scanned sections are selected. In the present example, the selected scanned sections include scanned sections 210 and 214. Angio value 208 corresponds to scanned section 210, and Angio value 212 corresponds to scanned section 214. Therefore, Angio values 208 and 212 are selected. At step 408, a derivative value is generated based on the selected Angio values. The derivative value is a spatial derivative of the selected Angio values. In the present example, the derivative value is simply the difference between Angio values 208 and 212. At step 410, a composite value is generated based on the derivative value, the corresponding Anglo value, and a predetermined constant. More specifically, a composite value may be generated by multiplying the corresponding Angio value by a first coefficient to generate a first product, multiplying the derivative value by a second coefficient to generate a second product, and adding the first product and the second product to a predetermined constant. At step 412, a color value for the selected image subregion is determined based on the composite value according to the established correlation. In the present example, a shade of gray would be determined for image subregion 224 based on the composite value generated at step 410 according to the correlation established in step 400. At step 414, it is determined whether all of the image subregions of the image 204 have been processed. If all of the image subregions have been processed, a color value has been determined for each region of the image 204, and the image 204 may be displayed. If all of the image subregions have not been processed, control passes back to step 402 and an unprocessed image subregion is selected. This process continues until a color value has been determined for each region of the image 204. While specific embodiments of the present invention have been described, various modifications and substitutions will become apparent to one skilled in the art by this disclosure. Such modifications and substitutions are within the scope of the present invention, and are intended to be covered by the following claims.	A method and apparatus for displaying an image representing the flow of a substance in a scanned area. An Angio scanner scans a region of tissue and generates Ultrasound Angio data representing the flow of blood in the region of tissue. Relatively small blood flows are difficult to detect in images based solely on Angio data. To enhance the visibility of small blood flows, spatial derivative values are calculated from the Angio data. A fraction of the original Angio data plus a bias is summed with the spatial derivative values to generate composite values. An image of the scanned region is displayed with colors or grayscale shades based on the composite values. The resulting image depicts blood vessels in an edge-enhanced format, giving a three-dimensional appearance.	6
[0001] This application is a Continuation of co-pending application Ser. No. 11/062,429 filed Feb. 23, 2005, which is a Continuation of application Ser. No. 09/760,840, filed on Jan. 17, 2001, now U.S. Pat. No. 6,918,133, issued Jul. 12, 2005, and for which priority is claimed under 35 U.S.C. § 120; and this application claims priority of Application No. P2000-2065 filed in Republic of Korea on Jan. 17, 2000 under 35 U.S.C. § 119; the entire contents of all are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a digital broadcasting, and more particularly, to a method for identifying extender text tables of an electronic program guide in a digital television. [0004] 2. Description of the Related Art [0005] Generally, video and audio streams are compressed as digital information while system and program information are compressed in accordance with a program and system information protocol (PSIP) to provide digital broadcasting. Here, program information is decoded from data other than the video and audio information, and displayed on a screen for a user through an electronic program guide (EPG). The EPG and system information are combined into the PSIP and as the ATSC standard for ground wave and cable digital broadcasting, the PSIP provides a variety of information on programs by parsing messages encoded through a moving picture experts group (MPEG-2, ISO/IEC 13818-1 system) method (1997 DEC. document A/65). [0006] The PSIP includes a plurality of tables to transmit and receive A/V data generated in MPEG-2 video and AC-3 audio formats, and to transmit information and programs on channels of broadcasting stations. Accordingly, the PSIP enables a primary function of providing A/V services for broadcast programs of selected channels as well as a secondary function of providing guide services, i.e. EPG, for the broadcast programs. Particularly, information such as information on channels for channel-selecting and packet identification digits (PID) for A/V reception is transmitted through a virtual channel table (VCT), while EPG information on broadcast programs for the channels is transmitted through an event information table (EIT). [0007] The EIT is information regarding the events of virtual channels and includes a title and start time of each event. Here, an event is typically a TV program. Also, the PSIP can transmit at least four and at most one hundred twenty eight EITs in the format of EIT-k, where each EIT provides an event information of a specific time band. [0008] The PSIP further includes a system time table (STT) which provides time information; a rating region table (RRT) which transmits information on regions and rating organizations, i.e. ranking programs; an extender text table (ETT) which further explains channels and broadcast programs; and a master guide table (MGT) which manages the version and PID of each table. These tables are transmitted by data structures called sections. Namely, a section is the elementary unit of each table and one or more section(s) are combined to form a complete table. Accordingly, to facilitate user interface, the EPG representing information on programs to be broadcasted on a digital television (DTV) has a variety of formats depending on the section(s) defining a table. [0009] A widely used format of the EPG is by using a Gemstar table. In such format, an ETT which contains detailed information on an event, i.e. a broadcast program, can have event information corresponding to a unit of three hours. Also, each event information is represented and identified by an index based on a chronological order of EIT-1, EIT-1, . . . , EIT-127. Thus, an ETT is mapped with each corresponding EIT, i.e. event information corresponding to EIT-0 is mapped with ETT-0, event information corresponding to EIT-1 is mapped with ETT-1, . . . , and event information corresponding to EIT-127 is mapped with ETT-127. Here, an EIT can also represent information on events of up to three hours in a single section, where each event has an event_id field for identifying the event and an ETM_location field for displaying whether an ETT which contains detailed information on the event is present. [0010] Furthermore, each section of the ETT comprises an ETM_id representing an event or a channel as well as detailed text information on the event or channel. The sections of tables used in PSIP have syntax types as follows. table_id 8 bits section_syntax indicator 1 bits private_indicator 1 bits reserved 2 bits section_length 12 bits table_id_extension 16 bits reserved 2 bits version_number 5 bits current_next_indicator 1 bits section_number 8 bits last_section_number 8 bits protocol_number 8 bits actual_table_data * CRC_32 32 bits [0011] The table sections, as listed above, can be for section headers of tables which have common rules of composition or for section bodies of tables which have different contents depending on the objective of a table. Here, a section header has basic information such as table_id, table_id_extension, version_number, and section_number, which identifies a section in the section header. Specific field value(s) based on such basic information which identify section(s) within the section header can be used to extract certain section(s). Namely, the section(s) with basic information which match the specific field value(s) can be extracted. This process is known as section filtering. [0012] General formats of EIT and ETT are shown in FIG. 1 . As shown, a section EIT-0 within an EIT includes a plurality of events, where each event is distinguished or identified by the event_id and the ETM_location indicates whether an ETT exists for the identified event. Also, an ETM_id within each ETT section is represented by a source_id+event_id+1sb and indicates the event to which the ETT section corresponds. For example, in the ETM_id of ‘XX . . . X00000000000011XX’ shown in FIG. 1 , the underlined portion represents an event mapped with a corresponding event_id. In other words, an ETT-0 has a link with a corresponding event through the ETM_id in the section body. [0013] However, information in the section header of the ETT-0 such as the table_id, the table_id_extension, the section_number, and the last_section_number includes the same value of ‘00000000000011’ regardless of the section. Namely, each section has the same section header, excluding the version field. Thus, to process an ETT, required contents of the ETT are randomly extracted through a section header filtering according to a sequential process as shown in FIG. 2 . [0014] Referring to FIG. 2 , an ETT section filter is first set (S 1 ) and the ETT section-outs, which have been received, are detected (S 2 ). All received ETT sections are then input (S 3 ) and the input ETT sections are parsed (S 4 ). Next, an ETM_id is detected depending on the result obtained from parsing the ETT sections (S 5 ) and the detected ETM_id is compared with an event_id to determine if the values are identical (S 6 ). If the detected ETM_id is identical to the event_id, the ETM_id is stored as a text message (S 8 ) and the processing of the ETT ends. Otherwise, the corresponding section is dumped (S 7 ) and a next ETM_id is detected and compared to the event_id by repeating the above process. [0015] However, a method for identifying ETTs of an EPG of a DTV according to the related art has the following problems. [0016] First, because the section headers of ETT sections are basically identical, a general section filtering cannot be conducted. Thus, all sections of, for example, ETT-0 corresponding to an EIT-0 are received and parsed to select a required ETT-0 section, resulting in a repeated processing of an ETT section. Second, upon receiving a command to identify whether the contents of an ETT-0 section has been changed when a version number is altered, the entire ETT-0 sections must be parsed to detect an ETM_id. Third, if ETT sections are not the same version, a section filtering based on the version cannot be performed. In other words, the method, in which different sections of the ETT-0 have the same section header, fails to meet the system standard of the moving picture experts group (MPEG) as well as to perform a section filtering of sections using the header. SUMMARY OF THE INVENTION [0017] Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art. [0018] An object of the present invention is to provide a more efficient digital broadcasting. [0019] Another object of the present invention is to provide a more efficient method for identifying ETTs. [0020] A further object of the present invention is to provide a method for processing ETT section header to identify ETTs. [0021] A still further object of the present invention is to identify ETTs by processing ETT sections in the same manner as other tables of PSIP. [0022] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. [0023] To achieve the objects and in accordance with the purposes of the invention, as embodied and broadly described herein, a method for identifying ETTs of an EPG in a DTV according to an aspect of the present invention includes inputting an event_id in a table_id_extension within ETT sections such that the ETT sections are identified at a receiving or a transmitting party without parsing the ETT sections. Preferably, the ETM_location values within the ETT sections are distinguishably represented such that it is possible to determine whether the ETT is transmitted from a same channel or from another channel being broadcasted. Also, ETT section headers among the ETT sections is preferably represented to determine whether the ETT section includes detailed information for channels or for events. BRIEF DESCRIPTION OF THE DRAWINGS [0024] The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: [0025] FIG. 1 shows an EIT and ETT in the related art; [0026] FIG. 2 is a flowchart of a method for processing ETT sections in the related art; and [0027] FIG. 3 is a flowchart of a method for processing ETT sections according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0028] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail. [0029] According to the present invention, ETT sections are generally identified by a section header through a table_id_extension. Namely, an event_id is input into the table_id_extension to represent a corresponding event. Thus, a general section filtering method can be used to process only the section(s) necessary at a receiver. [0030] A method for identifying ETTs of an EPG in a DTV according to the present invention will next be described in detail, where Table 1 below shows the syntax types of table sections used in the PSIP. TABLE 1 Bit stream syntax for the ETT in A/65(PSIP document) extended_text_table_section ( ) { table_id 8 0xC7 section_syntax_indicator 1 ‘1’ private_indicator 1 ‘1’ reserved 2 ‘11’ section_length 12 uimsbf table_id_extension 16 0x0000 uimsbf reserved 2 ‘11’ version_number 5 uimsbf current_next_indicator 1 ‘1’ section_number 8 0x00 last_section_number 8 0x00 protocol_version 8 uimsbf ETM_id 32 uimsbf extended_text_message( ) var CRC_32 32 rpchof } [0031] The present invention distinguishes and identifies the ETT sections by inserting an event_id into a table_id_extension, where the table_id_extention is commonly used in ETT header sections with a fixed value of 0x00. Particularly, a table_id_extension is composed of 16 bits and according to the present invention, 14 bits of the 16 bits represent an event_id and residual 2 bits remain. One of the residual 2 bits may be used for identifying whether a value of an ETM_location is 0x01 or 0x02, and the other residual bit may be used for identifying whether the ETT section is related to channels or to events. [0032] For example, an ETM_location value of 0x01 may indicate that the ETT is transmitted from the same channel as the EIT. In such case, an ETM_location value of 0x02 would indicate that the ETT is transmitted from a channel actually being broadcasted. Accordingly, whether an ETT section is related to channels, which are currently being transmitted, or related to events can be determined by values of 0x01 or 0x02 represented in the table_id_extension. Also, the other bit contains information on whether an ETT section has detailed information on channels or on events, and can be distinguished through the ETT section header. [0033] For example, a table_id_extension may be composed as shown in Table 2 below. TABLE 2 table_id_extension (16 bits) event/ value corresponding channel to ETM-location event-id 0/1 0/1 XX XXXX XXXX XXXX [0034] By inputting a value, which can distinguish and identify an ETT section, into the table_id_extension as shown in Table 2, a section filtering can be executed and thus, required ETT section(s) can be selectively received. For example, if an event_id requires detailed information on events represented in ‘00 0000 0000 1111,’ the event_id selectively receives ETT section(s) having a table_id of 0xCC and table_id-extension having values corresponding to ‘ 00 0000 0000 1111 .’ [0035] Referring to FIG. 3 , in processing an ETT according to the present invention, an ETT section filter is initially set (S 10 ). The ETT section-outs are then detected (S 20 ), and pertinent ETT section(s) is(are) filtered and detected (S 30 ) using the event_id inserted in the table_id_extension of the ETT sections. Next, the detected ETT section(s) is(are) parsed (S 40 ) and the parsed section(s) is(are) stored as a text message (S 50 ). [0036] Accordingly, in the present invention, an ETT of EPG is generated by inserting an event_id in a table_id_extension of each ETT section header to identifies an event to which an ETT section corresponds. Also, an ETM_location value may be inserted in the table_id_extension to distinguish whether an ETT section is transmitted from the same channel as EIT, and/or a value may be inserted in the table_id_extension to distinguish whether detailed information in an ETT section is for channels or for events. [0037] Similarly, a method for identifying ETTs of an EPG comprises inserting an event_id in a table_id_extension of each ETT sections before transmitting the ETT sections to a receiver; and section filtering, at the receiver, the received ETT sections based upon the event_id to identify an ETT section. Namely, an ETT section can be identified by setting an ETT section filter; detecting ETT section-outs; section filtering and detecting at least one pertinent ETT section using the event_id in the table_id_extension of each ETT sections; parsing the detected at least one ETT section; and storing each parsed ETT section as a text message. [0038] Furthermore, if the table_id_extension is available for section identification, a version processing according to the section can be performed. Specifically, when contents of a section changes, a version_number is accordingly altered to represent the change. As a result, a transmitter can determine which ETT section is to be transmitted with changed contents by referring to a section header, and can produce and use a section filter. Thus, if the contents of a section among the ETT sections are changed, a transmitter can change the version of section(s) for section(s) with changed contents because the sections are distinguishable. Similarly, a receiver can filter and receive the section(s) with values corresponding to the changed version. Namely, ETT sections can be filtered at the receiver by detecting ETT sections with values corresponding to a specific version. [0039] As described above, a method for identifying ETTs of an EPG in a DTV according to the present invention has the following advantages. First, the method can filter ETT sections without receiving all sections and/or repeatedly filtering the unnecessary sections. Second, the method may use a value which can identify each ETT section and allow a control of the version. Third, the method maintains an existing section header while employs a table_id_extension field of 0x00, i.e. the same value as in the section header, thereby being compatible with existing receivers. [0040] The foregoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.	A method for identifying extender text tables of an electronic program guide in a DTV is disclosed. In the present invention, the extender text tables are identified by processing an ETT section in the same manner as other tables using a value capable of identifying the extender text table sections. Particularly, an event_id is input in a table_id_extension within ETT sections, so that the ETT sections can be identified at a receiving or a transmitting party without parsing the ETT sections.	7
BACKGROUND OF THE INVENTION [0001] This invention relates generally to circuits known as charge pumps and, more particularly, to charge pumps as used in conjunction with phase-locked loops (PLLs). Phase-locked loops are widely used in a variety of applications in which a time-varying signal must be synchronized (locked) with a reference signal. Typical applications include frequency synthesizers for radio receivers and transmitters, demodulation of radio signals, and recovery of clock timing information from received radio signals or from digital storage devices. A common PLL configuration includes a phase detector, a charge pump, a loop filter, and a voltage controlled oscillator, the output of which is fed back as an input to the phase detector. The theory of operation of PLL circuits that include a charge pump is well known in the art. Basically, the phase detector generates signals indicative of the phase difference between a time-varying signal and a reference signal. Then the charge pump, controlled by output signals generated by the phase detector, adds (or subtracts) a controllable amount of charge, i.e., current, to (or from) an output signal that it generates. This output signal is smoothed by the loop filter and then used to provide a voltage that controls the voltage controlled oscillator. [0002] A conventional charge pump in the context of a PLL consists of a number of current switches, which are turned on and off under control of signals generated by the phase detector. Conceptually, the charge pump is sometimes described as being part of the phase detector, but for purposes of the present invention the charge pump is best considered a separate device. Charge pump circuits for PLL applications are extremely critical if low noise operation is desired. Conventional charge pump circuits contain multiple current sources that are switched on or off depending upon the desired pump output current. These switching operations necessarily result in abrupt changes in total current drawn by the charge pump circuit, and these abrupt current changes result in noise components that can modulate onto the power supply itself and adversely affect other sensitive components of the PLL. [0003] Accordingly, there is a need for an improved charge pump circuit, or an adjunct to an existing charge pump circuit, which eliminates these switching noise components and enhances the overall performance of the PLL in which the charge pump circuit is employed. The present invention is directed to this end. SUMMARY OF THE INVENTION [0004] The present invention resides in a charge pump bias network that can be coupled to any of a variety of differently configured charge pump circuits, to reduce or eliminate unwanted noise components that would otherwise be introduced by switching operations of the charge pump circuit. Briefly, and in general terms, the charge pump bias network of the present invention comprises a power supply; a first circuit for drawing a desired current from the power supply to a charge pump circuit, based on a digital control signal indicative of a currently desired current setting for the charge pump circuit; and a second circuit, interconnected with the first circuit, for drawing a complementary current from the power supply to a replica charge pump circuit. A practically constant total current is drawn from the power supply, regardless of fluctuations in the desired current setting for the charge pump circuit, as reflected in the digital control signal. Therefore, abrupt changes in power supply current are avoided and resultant switching noise effects are minimized. The terms “replica charge pump circuit” and “electrical replica of the charge pump circuit” as used in this description are intended to mean either a circuit that duplicates all the components of the charge pump circuit, or a circuit or load that has essentially the same electrical characteristics as the charge pump circuit. In many instances, the replica charge pump circuit may be simply a “dummy” electrical load with impedance characteristics that mimic those of the charge pump circuit. [0005] The charge pump bias network further comprises means for converting the digital control signal to a first current indicative of the desired current setting for the charge pump circuit, and simultaneously converting the digital control signal to a second current complementary to the first current. The first circuit further comprises a first current mirror, for mirroring the first current to the charge pump circuit, and the second circuit further comprises a second current mirror, for mirroring the second current to the replica charge pump circuit. [0006] More specifically, the means for converting the digital control signal to the first and second currents comprises a plurality of current sources, weighted in accordance with the binary weights of respective bits in the digital control signal; and an equal plurality of two-position switches coupled to the respective current sources and having first and second output terminals. All of the first output terminals of the switches are coupled together to the first current mirror, all of the second output terminals are coupled together to the second current mirror, and the digital control signal is coupled to the plurality of switches to control their positions. [0007] Using alternative wording, the charge pump bias network may also be defined as comprising a plurality (N) of binary-weighted current sources; an equal plurality (N) of two-position switches coupled to respective binary-weighted current sources, wherein each switch is controllable to connect a current source to a first output terminal or a second output terminal; a first common line connecting all the first output terminals of the switches to a first current mirror; a second common line connecting all the second output terminals of the switches to a second current mirror; and a power supply connected to supply current to the first and second current mirrors. The first current mirror is configured to mirror the current in the first common line to charge pump circuit, and the second current mirror is configured to mirror the current in the second common line to a replica charge pump circuit. An N-bit word that digitally defines a charge pump current setting at any given time is coupled to the switches to provide the desired charge pump current through the first common line, which is mirrored to the charge pump circuit. Simultaneously, a complementary current is provided to the second common line and mirrored to the replica charge pump circuit. This current is complementary in the sense that the total current drawn from the power supply remains constant, regardless of the charge pump current demand. [0008] The invention may also be defined as a method for minimizing current switching effects in a charge pump circuit. The method comprises the steps of representing a desired charge pump current setting as digital word; generating a set of current signals proportional to binary-weighted components corresponding to the digital word; applying the set of current signals to a set of two-position switches, each with first and second output terminals; applying the digital word as a set of binary signals to control the set of two-position switches and thereby switching each of the binary-weighted current signals to the first or second output terminal of each corresponding switch; combining output currents from the first output terminals of the switches and applying the result as a first common current signal to a first current mirror; and combining output currents from the second output terminals of the switches and applying the result as a second common current signal to a second current mirror. The method further comprises mirroring, in the first current mirror, the first common current signal to the charge pump circuit; and mirroring, in the second current mirror, the second common current signal to a replica of the charge pump circuit. The current mirrored to the replica of the charge pump circuit is complementary to the current mirrored to the charge pump circuit, in the sense that the two currents always sum to a constant current drawn from a common power supply. [0009] It will be appreciated from the foregoing that the present invention represents a significant advance in charge pump circuits, as used in conjunction with phase-locked loops (PLLs). In particular, the charge pump bias network of the invention minimizes or eliminates noise effects resulting from current switching operations of a charge pump circuit. Other aspects and advantages of the invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. 1 is a block diagram of a phase-locked loop of the prior art. [0011] FIG. 2 is a block diagram showing in more detail how a charge pump circuit of the prior art operates in a phase-locked loop. [0012] FIG. 3 is a functional schematic diagram of a charge pump bias network in accordance with the present invention. [0013] FIG. 4 is a block diagram showing how the charge pump bias network of the invention interfaces with a charge pump circuit. DETAILED DESCRIPTION OF THE INVENTION [0014] As shown in the drawings for purposes of illustration, the present invention is concerned with charge pump circuits as used in phase-locked loops (PLLs). FIG. 1 shows the basic components of a PLL, including a phase detector 10 , a charge pump 12 , a loop filter 14 and a voltage-controlled oscillator (VCO) 16 . The VCO 16 generates an output signal at a desired frequency and also feeds back this signal to the phase detector 10 . If, for example, the phase of the oscillator output signal falls behind the phase of a reference signal applied to the phase detector 10 , the phase detector causes the charge pump to increase its output, which is used to control the VCO to speed up the output signal. Similarly, if the output signal from the VCO 16 leads the phase of the reference signal, the phase detector 10 causes the charge pump circuit 12 to slow the VCO 16 . The loop filter 14 is basically a low-pass filter that smoothes out the abrupt control signals from the charge pump 12 . This feedback control system tends to converge on a state in which the phase detector 10 makes only very few small corrections. Many PLLs also include an N: 1 frequency divider (not shown) between the VCO 16 and the phase detector 10 . The effect of the divider is that when the PLL locks, the VCO 16 generates an output of N times the frequency of the reference signal. [0015] The principle of operation of the conventional charge pump circuit 12 is illustrated in FIG. 2 . In its simplest form, a charge pump circuit 12 comprises two current sources 20 and 22 and two switches: an UP switch 24 and a DOWN switch 26 . When the phase detector 10 determines that the oscillator frequency should be increased, it generates an output pulse on line U (up), and when the phase detector determines that the oscillator frequency should be decreased, it generates an output pulse on line D (down). A pulse on line U or D results in closure of either the UP switch 24 or the DOWN switch 26 . Moreover, it will be apparent from FIG. 2 that closure of the UP switch results in output of a positive output pulse of current from the charge pump 12 , and closure of the DOWN switch 26 results in a negative output pulse of current from the charge pump, i.e., current flows into the charge pump from the loop filter 14 . The filter 14 is shown as including a resistor R and capacitor C connected in series between the charge pump output and ground. Thus, a positive output current pulse from the charge pump 12 results in charging of the capacitor C and an increase in the voltage output from the loop filter, and a negative current pulse results in discharge of the capacitor C and a decrease in the voltage output from the loop filter. In effect, the charge pump 12 illustrated has three possible switching states. Either both switches 24 and 26 are off (and no charge is added to or removed from the loop filter 14 ), or only the UP switch 24 is closed (resulting in adding charge to the loop filter), or only the DOWN switch 26 is closed (resulting in removal of charge from the loop filter). Normally, the phase detector 10 would not close both switches 24 and 26 at the same time. [0016] Different design configurations of charge pumps may include more than just two switches but charge pumps all operate in principle the same way. That is to say, they all contain multiple current switches that are controlled to add charge to or remove charge from a downstream circuit, which as a consequence generates an appropriate output voltage to control the VCO 16 and to move the PLL toward a phase-locked state. Therefore, conventional charge pumps in PLLs contain current switches that necessarily and abruptly change the current drawn from the charge pump power supply. As noted above, these abruptly operated current switches may introduce noise components that affect operation of the PLL, especially at higher frequencies. [0017] In accordance with the present invention, a charge pump includes a bias network that ensures that the current drawn from the charge pump power supply remains constant. The principle of the bias network of the invention is shown in FIG. 3 . The bias network includes multiple current sources 30 , of which four are shown, and an equal number of binary switches 31 . The current sources 30 generate currents that are binary fractions of each other. That is to say, the first source 30 generates a current I 1 , the second one a current ½ I 1 , the third one ¼ I 1 and the fourth one ⅛ I 1 . Each source 30 draws current through one of the switches 31 , which are controlled by four binary signals A, B, C, and D, respectively. Each switch 31 in its first position draws current along a common path 32 and through a first current mirror 33 . Each switch in its second position draws current along a second common path 34 and through a second current mirror 35 . [0018] A current mirror is a conventional circuit having first and second current paths, in which current in the first path is closely duplicated, or mirrored, in the second path. Some current mirrors are designed to produce an amplified current in the second path. In the present application of current mirrors, current in the first common path 32 , to which some combination of the currents through sources 30 contributes, is mirrored in a current path 36 extending to a charge pump, shown for convenience as a resistor 37 . Similarly, current in the second common path 34 is mirrored by the second current mirror 35 in a current path 38 connected to a replica charge pump 39 . The replica charge pump may be a circuit that exactly duplicates every component of the charge pump or it may be simply an electrical replica of the charge pump, such as a “dummy” load. [0019] The switches 31 are at any instant in time positioned in accordance with the binary word ABCD, which also represents the charge pump current setting at that instant. Each current source 30 is connected either to current mirror 33 or current mirror 34 , depending on the position of the corresponding switch 31 . If all the switches 31 are “on,” meaning that all the current sources 30 contribute to current through common line 32 , the total of the current contributions is mirrored in the charge pump current and virtually no current flows to the other current mirror 35 . More generally, any current contribution from the sources 30 that does not contribute to path 32 through current mirror 33 , goes instead to path 34 through current mirror 35 . Stated another way, because the total current through sources 30 remains constant, the total of the currents in lines 36 and 39 is always constant, and this is the total current drawn from the power supply by the charge pump 37 and the replica charge pump 39 . If the charge pump current is I cp , then the replica charge pump current is I cp(max) −I cp , where I cp(max) is the maximum charge pump current. Note, however, that I cp(max) in this relationship does not include the current drawn from the power supply through common lines 32 and 34 by the current sources 30 . If the current mirrors 33 and 35 are without current amplification, the total current drawn from the power supply would be 2 I cp(max) . [0020] The pump bias circuit of FIG. 3 may be implemented in a variety of ways. For example, the current sources 30 may be NPN bipolar transistors with appropriately selected resistors in the emitter circuits to provide the binary relationship between adjacent current sources. Each of the switches 31 may be a differential pair of NPN bipolar transistors with the collectors connected in common and with complementary control signals applied to the bases of the pair. The current mirrors 33 and 35 may also be implemented in various ways. For example, each may include a PFET (p-channel field-effect transistor) connected between one of the common lines 32 and 34 to the power supply, and configured to mirror the current in the PFET to another current source, located in line 36 to the charge pump circuit or in line 39 to the replica charge pump circuit. [0021] FIG. 4 depicts how the charge pump bias network of FIG. 3 is typically interfaced with the charge pump 37 . The illustrative charge pump 37 includes two current generators 40 and 41 , which generate positive and negative charge, respectively to be coupled to the loop filter 14 . The current generators 40 and 41 are shown as generating source and sink currents I p and I n , respectively. Ideally, these currents should be identical to I cp or a multiple of I cp supplied by the pump bias network of FIG. 3 . The phase detector 10 generates UP or DOWN switching signals, which are used to control the charge pump switches 42 . A source/sink current generator 44 receives the current I cp from the charge pump bias network over line 36 , and mirrors this current onto the current generators 40 and 41 through the two output lines 46 and 48 . Other charge pump configurations are, of course, possible and would necessitate modifications to this interface circuitry. [0022] The present invention maintains the overall power supply current at a substantially uniform level, even while current drawn by the charge pump circuit is abruptly switched to different levels as the charge pump operates to synchronize time-varying signals in a PLL. Therefore, the invention minimizes or eliminates the effects of abruptly varying the current consumed by the charge pump circuit. The only significant drawback to the invention is that maintaining the power supply current at a constant level comes at the expense of having a higher average power consumption than a circuit in which the power supply current varies in accordance with the needs of the charge pump. [0023] It will also be appreciated that although a specific embodiment of the invention has been described in detail for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited except as by the appended claims.	A circuit for supplying selected currents to a charge pump without harmful effects arising from operation of current switches in the charge pump. A charge pump current setting is applied in digital form to a set of two-position switches coupled to binary-weighted current sources. Currents from the sources selected by the switches are combined, and the total current is mirrored to the charge pump. Simultaneously, those of the binary-weighted current sources not selected by the switches to contribute to the charge pump current are separately combined, and this total current is mirrored to an electrical replica of the charge pump. Thus the currents supplied to the charge pump and to the replica charge pump are complementary in the sense that they always add to a constant total current drawn from a common power supply. Therefore, abrupt changes in current load are avoided and switching noise effects are minimized.	7
BACKGROUND OF THE INVENTION [0001] This invention relates to an air charging device, particularly to one used as a children's amusement swimming pool, an aquatic amusement boat, a temporary water-stopping wall, an amusement course or the like, able to endure bumping and prevent leaking. [0002] A conventional air charged appliance, as shown in FIG. 1, is made of single-layer PVC plastic cloth 110 . An air charged appliance made of such a plastic cloth 110 is likely to leak quickly after it is filled in air and used for a short time, therefore it is not suitable for being used as a children's toy swimming pool, an aquatic raft, a temporary water-stopping wall, a guiding obstacle for an amusement course or the like. [0003] For instance, as shown in FIG. 2, in case the conventional air charged appliance is used as solid obstacles 11 of an amusement course or a training course, it has to be continually pumped in air by means of a pump 1 so as to provided adequate air for the solid obstacles 11 respectively connected with the air-transporting pipes 10 , otherwise the obstacles 11 may become softened resulting from quick leaking of its interior air because they are made of single-layer PVC. Further, the air transporting pipes 10 connecting the obstacles 11 are exposed on the ground so they are liable to trip those who are playing around and hurt them. [0004] In addition, the pump 1 has to operate incessantly in order to pump air into the obstacles 11 , not only wasting electricity, but making noises as well. SUMMARY OF THE INVENTION [0005] The objective of this invention is to offer an air charged appliance used as a children's toy swimming pool, an aquatic raft, a temporary water-stopping wall, a guiding obstacle for an amusement course or the like, capable of enduring bumping and preventing leaking. [0006] The feature of the invention is an air charged appliance made to have any shape for the purpose, consisting of one or more than one air chambers and one or more than one air sacs placed in the air chamber(s). The air chamber and the air sac are made separately. Then the air sac is inflated or deflated to inflate or deflate the air chamber together at the same time. BRIEF DESCRIPTION OF DRAWINGS [0007] This invention will be better understood by referring to the accompanying drawings, wherein: [0008] [0008]FIG. 1 is a partially magnified side cross-sectional view of a conventional air-filled obstacle: [0009] [0009]FIG. 2 is a top view of an amusement course with conventional air-filled obstacles: [0010] [0010]FIG. 3 is a perspective view of an air charged appliance in the present invention: [0011] [0011]FIG. 4 is a cross-sectional view of the air charged appliance in the present invention: [0012] [0012]FIG. 5 is a perspective view of a first embodiment of the air charged appliance used as an obstacle in the present invention: [0013] [0013]FIG. 6 is a perspective view of the first embodiment of the air charged appliance used as an obstacle not filled with air in the present invention: [0014] [0014]FIG. 7 is a perspective view of a second embodiment of the air charged appliance used as an obstacle not filled with air in the present invention: [0015] [0015]FIG. 8 is a perspective view of a third embodiment of the air charged appliance used as an obstacle not filled with air in the present invention: [0016] [0016]FIG. 9 is a perspective view of a fourth embodiment of the air charged appliance used as an obstacle not filled with air in the present invention: [0017] FIGS. 10 (A), 10 (B) and 10 (C) are cross-sectional views of the air charged appliance in various shapes in the present invention: [0018] [0018]FIG. 11 is a cross-sectional view of a fifth embodiment of the air charged appliance used as an obstacle in the present invention: [0019] [0019]FIG. 12 is an upper view of the fifth embodiment of the air charged appliance used as an obstacle in the present invention: [0020] [0020]FIG. 13 is a perspective view of a sixth embodiment of the air charged appliance used as an obstacle in the present invention: [0021] [0021]FIG. 14 is a perspective view of a first embodiment of an air charged appliance used as a swimming pool in the present invention: [0022] [0022]FIG. 15 is an exploded perspective view of the first embodiment of the air charged appliance used as a swimming pool in the present invention: [0023] [0023]FIG. 16 is a cross-sectional view of the first embodiment of the air charged appliance used as a swimming pool in the present invention: [0024] [0024]FIG. 17 is a perspective view of the first embodiment of the air charged appliances to be connected and used as a toy swimming pool in the present invention: [0025] FIGS. 18 (A) and 18 (B) are upper views of the first embodiment of the air charged appliances in different shapes in the present invention: [0026] [0026]FIG. 19 is a perspective view of an air charged appliance used as an aquatic raft in the present invention: [0027] [0027]FIG. 20 is a perspective view of a first embodiment of an expanded frame with a plurality of air charged appliances used as a water-stopping wall in the present invention: [0028] [0028]FIG. 21 is a cross-sectional view of the first embodiment of the collapsed frame in the present invention: [0029] [0029]FIG. 22 is an exploded perspective view of the first embodiment of the air charged appliance used as a water-stopping wall in the present invention: [0030] [0030]FIG. 23 is a perspective view of the first embodiment of the air charged appliance in a deflated condition assembled with the expanded frame to be used as a water-stopping wall in the present invention: [0031] [0031]FIG. 24 is a perspective view of the first embodiment of the air charged appliances in an inflated condition assembled with the expanded frame used as a wall-stopping wall in the present invention: [0032] [0032]FIG. 25 is a front view of the air charged appliances assembled with the expanded frame used as water-stopping wall positioned at the entrance of a basement in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0033] A preferred embodiment of an air charged appliance in the present invention, as shown in FIGS. 3 and 4, includes an air chamber 2 and an air sac 3 combined together. [0034] The air chamber 2 has an interior space for receiving the air sac 3 . The air chamber 2 is made of special nylon of high danier uneasy to break and able to endure bumping. The air chamber 2 has a fill opening 21 for the air sac 3 to be pushed in therethrough, and the fill opening 21 is provided with a fastening member 22 such as a velcro band or a zipper. Before filled with air, the air sac 3 is put into the air chamber 2 and then pumped in with air to become inflated together with the gas chamber 2 . Separated from the air chamber 2 , which is able to endure bumping, the air sac 3 itself can prevent leaking. [0035] Each air chamber 2 can receive one air sac 3 , as shown in FIGS. 3 and 4, or one or more air sacs 3 , and each air sac 3 is provided with an air valve 30 for filling in air independently. Thus, when the air charged appliance is used as a toy swimming pool or a raft, and should one of the air sacs 3 be broken, the circumferential wall of the toy swimming pool or the raft would not collapse, keeping the toy swimming pool or the raft functioning normally and ensuring the users' safety. [0036] In addition, the size of the interior space of the air chamber 2 may be made a little smaller than the air sac 3 so that the inflating size of the air sac 3 can be limited to prevent pump too much air so as to keep the air sac 3 elastic. [0037] Another preferred embodiment of the air charging device used as the obstacle (A) of an amusement course in the present invention, as shown in FIGS. 5 - 13 , includes an air chamber 2 and an air sac 3 . The air chamber 2 is provided with a plurality of nail-fastening rings 4 at the lower ends for fixing nails 40 to pass therethrough respectively and then nailed tightly into soft ground to stabilize the obstacle (A). [0038] In case the obstacles (A) for an amusement course is to be positioned on a hard ground such as a concrete ground, the air chamber 2 can be additionally provided with a receiving space 23 in the bottom to be filled in with heavy matter 24 such as liquid shown in FIG. 7, wooden planks shown in FIG. 8, stones shown in FIG. 9, or the like so long as it (they) can secure the obstacle (A) in position, regardless of the heavy matter made of any material. [0039] Furthermore, the air-filled obstacles (A) can be made in any solid shapes such as a solid square shown in FIG. 10(A), or a solid triangle shown in FIG. 10(B), or a solid arch shown in FIG. 10(C), or a safety obstacle with a net surface 25 shown in FIGS. 11 and 12, or a golf ball-receiving net 26 or a volley ball net, as shown in FIG. 13. If the air-filled obstacle (A) together with a net surface 25 is used as a safety obstacle or as a ball-receiving net 26 , it can be fixed on the ground by means of a plurality of bases 250 , 260 . [0040] Evidently, the air charging device of the invention has its air sac 3 filled in with air to become inflated together with the air chamber 2 , and the air inside the air sac 3 can hardly leak out, enabling the obstacle (A) maintain its shape and function normally. [0041] One more preferred embodiment of an air charging device used as a children's swimming pool (B) or a raft in the present invention, as shown in FIGS. 14 - 19 , includes a body 5 and air chambers 2 . The body 5 can be employed as the bottom of a swimming or a playing pool to be filled with a large amount of water, or as a receiving groove of a no-power raft for carrying persons to move on the water by paddling, as shown in FIG. 19, with the raft also possible to be provided with power. The body 5 is provided with a plurality of fastening members 51 (Velcro bands preferably), as shown in FIGS. 14 - 16 . [0042] Then, the body 5 may be provided inside with air chambers 2 , and each air chamber 2 has a fastening member 6 at a proper position, as shown in FIG. 17. After the body 5 receives the air chambers 2 and covers up part of them, the fastening members 51 of the body 5 and the fastening members 6 of the air chambers 2 are combined together to make up a toy swimming pool or a raft. Besides, the air chamber 2 can be composed of several air chambers 2 A and 2 B, which are connected together by means of the connecting members 2 AO and 2 BO provided at the opposite ends of each air chamber 2 A or 2 B to make up the wall of a pool or a yacht. The plural air chambers 2 A and 2 B can be arranged in any shapes. [0043] Moreover, the toy swimming pool or the raft in this invention can be made in various shapes, as shown in FIGS. 18A, 18B and 19 , therefore the body 5 is not necessarily to be made in a definite shape. [0044] Still one more preferred embodiment of an air charging device used as a water-stopping wall in the present invention, as shown in FIGS. 20 - 25 , includes an air chamber 2 and a frame 7 . [0045] The frame 7 is formed with an upper side 70 , a front side 70 and a rear side 70 respectively having a large number of ribs 700 arranged crosswise. Whether the ribs 700 are arranged densely or thinly depends on practical needs, and they are provided to confine the inflation direction of the air chamber 2 so as to fix it at a definite location. Then, the adjacent sides of the frame 7 are movably connected together by means of binding members 71 to make the frame 7 collapsible, as shown in FIG. 21. [0046] Additionally, the frame 7 has an open side 72 at opposite ends for the inflated air chamber 2 to expand out therethrough. The frame 7 is provided with a plurality of hooks 73 at the bottom to engage with the hook rings 74 , which are fixed and somewhat hidden on the ground so as to stably keep the frame 7 in place, with the hook rings 74 not protruding out of the ground. The frame 7 is further formed with an air chamber space 75 in the interior for receiving the air chamber 2 . [0047] In using, as shown in FIG. 23, the air chamber 2 is deposited in the air chamber space 75 of the frame 7 and then the air chamber 2 is filled up with air to become inflated and forced to move toward the opposite open sides 72 of the frame 7 . As the size of the inflated air chamber 2 is a little larger than the air chamber space 75 , the inflated air chamber 2 will expand outward and closely push against the ground 8 and the opposite walls 9 . Besides, the air chamber 2 is filled with air or air and liquid so it can completely and tightly push against the ground or the walls even if they are uneven, thus able to prevent water from getting into a basement or a room. [0048] While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications that may fall within the spirit and scope of the invention.	An air charged appliance includes an air chamber and an air sac, made in various shapes for different uses. The air sac is placed in the air chamber and filled up with air to become inflated together with the air chamber, but the both are made separately from each other. The air chamber is not easy to break and able to endure bumping so the air charged appliance can be used for a long period of time.	4
FIELD OF THE INVENTION The present invention relates to an image comparison apparatus for photographing, for example, a face of a person and making a comparison and a check, and more particularly to an apparatus and method for acquiring images and comparing them with previously memorized registration images and outputting a match if one exists. DESCRIPTION OF THE RELATED ART In general, in this kind of image comparison apparatus, an image of a person, acquired by using a camera, is checked against previously registered registration images so that the identity of the person in question is confirmed. For example, in the case where the image comparison apparatus is applied to a gate function for managing those entering and exiting a room, as shown in FIG. 7 , an image comparison apparatus 71 comprise an illumination device 72 , a camera 73 , a person detection sensor 74 , and a photograph start check button 75 , the apparatus 71 , is typically attached to a door 76 or a wall surface in the vicinity of the door. In the case where a person 77 enters or exits a room, the image comparison apparatus 71 , when the person 77 stops at a check position and presses down the check button 75 , photographs the face of the person 77 approaching the camera 73 , and the photographed face image is compared with previously registered face images to check and confirm consistence/inconsistence, and provides the basis for the entrance and exit being permitted or the entrance and exit being restricted of the person. In this case, as shown by the image information acquisition curve 81 of FIG. 8 , at the time when the person stops at the check position suitable for photographing by the camera and presses down the check button, the face image of the person can be obtained most accurately. On the other hand, there is known that as the person goes away from the position of the check button it becomes more difficult to accurately capture the face image of the person, and there is a tendency that the accuracy and stability of image information is lowered. When the check button is pressed down, if the person closes the eyes, opens the mouth, or looks away, causing the face image to appear different from the registered image, even if the person is the person in question, it is judged that the face image is a poor image and a recheck operation will check the image again. This recheck operation is repeated until the number of operations reaches the number of predetermined retry times, and if check confirmation can not be made, an input operation using a personal identification key or readout using a check card will be carried out. However, the number of retry operations are increased due to the recheck, it is inconvenient to the person attempting to enter or exit a room, and, a smooth use cannot be realized. Additionally, there is an increased processing time and delay at the entrance and exit. There also is an increased amount of labor to execute a check operation. SUMMARY OF THE INVENTION The present invention is to provide an image comparison apparatus and method, which has a high check function in which when an acquired image is obtained when a button for check confirmation is pressed down, and a plurality of images prior to the check button being pressed and are checked and confirmed. According to an aspect of the present invention, an image comparison apparatus in which an image of a photograph object is acquired by using photograph means, and in a case where a button for check confirmation is pressed down, the acquired image is compared with information concerning previously memorized registration images, and a comparison result is outputted, the image comparison apparatus characterized in that an object detection sensor for detecting existence of the photograph object is provided, the photograph means acquires a plurality of images of the photograph object during a period from detection of the photograph object by the object detection sensor to a press of the button, and in a case where the button is pressed, at least one of the plurality of acquired images is compared with the information concerning the previously memorized registration image. As a result, even if a check poor image is produced at the time of check of the photograph object when the button for check confirmation is pressed down, since the check can be made by using a complementary image obtained at the timing before that, the image suitable for check judgment of the photograph object can always be ensured at the time of check, a recheck operation is omitted, and a check processing can be carried out in a short time. According to another aspect of the present invention, an image comparison method comprises the steps of detecting existence of a photograph object, capturing a plurality of images of the photograph object in a case where the photograph object is detected, detecting a press of a button for check confirmation, comparing at least one of the plurality of captured images with information concerning previously memorized registration images when the press of the button is detected, and outputting a comparison result. If the photograph object is checked by the procedure of such comparison and check steps, even if a suitable check image is not obtained at the point of time when the button for check confirmation is pressed down, the check confirmation can be made by using another image, so that it becomes unnecessary to repeatedly press down the button, and the check process can be completed by one operation. According to another aspect of the present invention, an image comparison center apparatus compares a captured image with information concerning registration images previously memorized in memory means, and outputs a comparison result, in which the image comparison center apparatus is characterized in that a plurality of captured images of a same object are successively compared with the registration images memorized in the memory means, and as a result of the comparison a proper judgment result is outputted in a case where there is a similar image satisfying a check judgment threshold, and an improper judgment result is outputted in a case where there is no similar image satisfying the check judgment threshold in the plurality of images. If there is a similar image satisfying the check judgment threshold in the plurality of photographed images, the proper judgment result is outputted, and if there is no similar image satisfying the check judgment threshold, the improper judgment result is outputted, so that the plurality of images concerning the same object are used on a screen for check judgment, and check confirmation with high accuracy can be made. According to still another aspect of the present invention, an image comparison system captures an image of a photograph object by use of a photograph means, compares the captured image with registration images previously memorized in memory means, and outputs a comparison result, in which the image comparison system is characterized in that a plurality of captured images of a same object are successively compared with the information concerning the registration images memorized in the memory means, and as a result of the comparison, a proper judgment result is outputted in a case where there is a similar image satisfying a check judgment threshold, and an improper judgment result is outputted in a case where there is no similar image satisfying the check judgment threshold in the plurality of images. Since the check properness can be confirmed by successively comparing the plurality of photographed images with the the registration images memorized in the memory means, an image coincident with the registered image can be obtained without fail. According to still another aspect of the present invention, where an image acquired at the point of time when the button for check confirmation is pressed down is a check poor image, a check is made by using the image acquired nearest in time to the time the button is pressed from the plurality of images acquired prior to the press of the button. According to still another aspect of the present invention, a display means for displaying a check state at the time of check is provided. In this invention the check state, such as check success and check failure is displayed and guided at the time of the check, a photographed person can look at the display guide and can immediately determine confirmation, and the check processing can be executed while a sense of security is given to the photographed person. In the present invention the photograph object includes the face of a check person, and the whole and specific portions of various objects. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing an image comparison apparatus of the present invention; FIG. 2 is a diagram showing an image information acquisition curve and a photograph state of a camera; FIG. 3 is an explanatory view showing a lean angle state of a check object person who uses the image comparison apparatus of the present invention; FIG. 4 is a control circuit block diagram of an image comparison system of the present invention; FIG. 5 is a flowchart showing a check processing operation using the image comparison system of the present invention; FIG. 6 is a flowchart subsequent to FIG. 5 ; FIG. 7 is a schematic side view showing a use state of a conventional image comparison apparatus; and FIG. 8 is a diagram showing an image information acquisition curve and a photograph timing of a camera when a photograph is taken by the conventional image comparison apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be hereinafter described in detail with reference to the drawings. The drawings show an image comparison apparatus installed at an image acquisition side of an image comparison system in which a face of a person is photographed and is checked. As shown in FIG. 1 , the image comparison apparatus 11 is constructed by installing an operation panel 12 having a check data acquisition function on a door surface which is used for entrance and exit. The image comparison apparatus comprises an operation panel 12 that is attached at the height of a person's face, an illumination device 13 for illuminating the face is disposed at its upper portion, a camera 14 , a person detection sensor 15 , a check result display LED 16 , a check count display LED 17 , and a check start button 18 are disposed at its intermediate portion, and a personal identification key 19 and a card reader 20 are disposed at its lower portion. In the illumination device 13 , a plurality of illuminating LEDs are arranged, and illumination is made toward the forward position of the face height. The roughness state of a face of a person approaching the camera 14 is clearly illuminated to raise the face image acquisition performance of the camera 14 . The foregoing camera 14 photographs a face image by using a CCD camera or the like, and when a person approaches the front of the camera 14 , the person detection sensor 15 such as a reflection type infrared sensor detects the approach of the person, the camera 14 starts to photograph from the point of time of the detection until the check start button 18 is pressed down. During that period a plurality of face images of the person are photographed. Even if a check poor image is produced in an image acquired at the time when the check start button 18 is pressed down, for the purpose of making a check using a complementary image acquired at a time prior to the plurality of images as the complement are acquired. Thereafter, when the check start button 18 is pressed down, it is judged to be a check request of a person and the check is started. At this time, a check result of consistence or inconsistence of the person who was checked, is displayed on the check result display LED 16 . The check result display LED 16 is designed such that a light of a blue or red judgment result is turned on at one of two LEDs of different colors to enable recognition at a glance. Besides, at the time of the check, a check state, for example, a first check, or a second or third check due to failure of a check, is displayed in real time by the check count display LED 17 including a plurality of LEDs, so that the person being checked is made to clearly recognize it. Like this, it is possible to recognize the check properness by the lighting display of the check result display LED 16 and it is possible to grasp the check state by looking at the display guide of the check count display LED 17 , so that the person being checked can execute the check processing at ease without having a distrust or a sense of unease at the time of the check use. The person detection sensor is used, for example a light emitting diode for irradiating infrared rays as a light source, a reflection type distance detection function to detect the existence of the person being checked by detecting reflected light of the infrared rays. During the comparison process, not only can the check start button 18 be used, but also the personal identification key 19 may be used, or the card reader 20 may be used, and further, these may be used together. The personal identification key 19 and the card reader 20 have an independent check function, and if the person being checked inputs a given personal identification number for identifying the person being checked by using the personal identification key 19 , check confirmation is made based on the personal identification information and, the door being used for entrance or exit is unlocked. If the card reader 20 is used, the ID data of a card in which the ID data for identifying the person being checked is read out and recognized, the door is unlocked. FIG. 2 shows an image information acquisition curve 21 when the camera photographs the face image of the person being checked. The image information acquisition curve 21 shows that at the time when the check start button 18 is pressed down, the face information of the person being checked can be obtained most accurately and the stability of the image is increased. During the period between the detection of the person being checked by the person detection sensor 15 until the pressing of the check start button 18 , the camera 14 photographs the face image of the person being checked plural times and acquires the images, and in the case where the check start button 18 is pressed, at least one of the plurality of acquired images is compared with information concerning previously memorized registration images. At the comparison of the images, a proper judgment result is outputted in the case where there is a similar image satisfying a previously determined check judgment threshold, and an improper judgment result is outputted in the case where there is no similar image satisfying the check judgment threshold in the plurality of images. Thus, if the plurality of images concerning the same person being checked are used on the screen for check judgment, check confirmation with high accuracy can be made, and in the case of the registered person being checked, an image coincident with the registered image can be obtained without fail. As a result, even if the expression of the face at the point of time when the check start button 18 is pressed down is changed as compared with that at the normal time and is judged to be a check poor image, a recheck can be made by using the plurality of images previously taken. Particularly, since the person being checked is photographed plural times and the plurality of face images are obtained, the check confirmation can be made by any of the images, and the check processing can be completed by one button press operation without troubling the person being checked. When the plurality of acquired images of the person being checked are checked, the last image 23 acquired in order of time prior to the button being pressed 22 is used to make the check. The check can be made in order of timing near the image acquired at the point of time of the press of the button, which is most suitable for the check. Accordingly, as shown in FIG. 3A , in the case where the face of the person 31 being checked is directed toward the front, an image suitable for the check can be obtained. On the other hand, in the case where the face of the check object person 31 is directed obliquely upward as shown in FIG. 3B , or in the case where it is directed obliquely downward as shown in FIG. 3C , a slight lean angle θis produced in the eyes with respect to a front camera 32 . When the lean angle is θ=0°, the image becomes more stable, and when it exceeds θ=15°, a feature amount of the face cannot be accurately calculated, and the image becomes unstable. Accordingly, when only one image at the time of the press of the button is used, limitation occurs in the check processing. Therefore, the check is complemented by an after-mentioned control processing. FIG. 4 is a control circuit block diagram of an image comparison system, which is constructed by an image comparison center apparatus 41 for controlling the respective instruments provided on the operation panel 12 of the image comparison apparatus 11 , and a CPU 42 . The CPU 42 controls respective circuit devices along a program stored in a memory 43 , and the control data is memorized in the memory 43 . An image capture device 44 acquires an image photographed by the camera 14 , and causes it to be memorized in the memory 43 . The acquired image is displayed on a monitor 46 for monitoring through a display control portion 45 . A first input/output control portion 47 controls respective input/output data of the illumination device 13 , the person detection sensor 15 , the check result display LED 16 , the check count display LED 17 , and the check start button 18 , and a second input/output control portion 48 controls input from a keyboard 49 for an entrance and exit monitor room. An RS232C communication portion 50 has a communication connection function to transmit input data from the card reader 20 and the personal identification key 19 to the CPU 42 . A registration file 51 is provided as a database file at the time of registration of a face image, and the data of the face image feature amount of respective registered persons is stored here. The CPU 42 checks the face image information of the person photographed by the camera 14 against the previously registered registration information, and determines the consistence or inconsistency of the person being checked, and based on the judgment result, permission of entrance and exit or the restriction of entrance and exit is carried out. The entrance and exit state is displayed by the monitor 46 connected to the image comparison center apparatus 41 , and the data input and the opening control of the door by a supervisor are allowed using the keyboard 49 . A processing operation when a check use is made by using the image comparison system constructed by the preferred embodiment will be described with reference to flowcharts of FIGS. 5 and 6 . When a person who makes an entrance and exit use approaches the door of a room provided with the image comparison apparatus 11 , the person detection sensor 15 first detects and confirms the presence of a person (step n 1 ). On the basis of a detection signal of the sensor 15 , the camera 14 starts to photograph (step n 2 ), and the image obtained by the camera 14 is stored in the memory 43 of the image comparison center apparatus 41 (step n 3 ). At the time of the image acquisition, after one face image is acquired, a next face image is photographed for grasping a change in the eyes and direction of a face elapses (step n 4 ). A photograph is repeatedly taken until the person being checked presses down the check start button 18 . It is preferable that an upper limit of the number of acquired photographs is fixed, so that a photograph is not unnecessarily taken. When the person being checked presses down the check start button 18 (step n 5 ), the CPU 42 acquires an image of the person being checked immediately (step n 6 ). The CPU 42 compares and checks the acquired face image with previously registered face images, and determines the degree of similarity. At the judgment, the face feature amount of eyes, a nose, a mouth or the like which becomes features at the check time is extracted and are checked (steps n 7 to n 10 ). If the check judgment results in consistence, the check result display LED 16 displays the consistence by lighting (steps n 11 to n 12 ), and the check count display LED 17 displays that the check processing is the first and that the check result is the consistence (steps n 13 to n 14 ), and at the same time, the door for entrance and exit is unlocked, and the entrance and exit of the person being checked is permitted (step n 15 ) On the other hand, in the case where the CPU 42 judges that the check is impossible, an automatic check judgment is repeatedly carried out within the limit of the previously determined number of check times (step n 16 ). For example, when the image acquired immediately after the press of the check start button 18 is checked, and is judged to be a check poor image since the person being checked closes the eyes, opens the mouth or looks away, so that the CPU 42 makes a judgment of improper judgment result, the check result display LED 16 displays check processing failure by lighting (step n 17 ), and at the same time, the check count display LED 17 displays and guides how many times the check processing has been repeated (step n 18 ). At the time of the recheck, after the lights of the check result display LED 16 are put out (step n 19 ), the CPU 42 extracts an image at a time prior to the point of time of the press of the button among the plurality of acquired images of the person being checked and starts to recheck (step n 20 ). If the consistence is not obtained though the recheck is made, the recheck is further made by using the acquired image in order of time prior to the press of the button. If consistence is not obtained, a similar recheck operation is repeatedly carried out, and when the number of operations reaches the previously determined check limit number of times, another check means is shown, and if the person being checked inputs a personal identification number by using the personal identification key 19 , or the card reader 20 is used to read the card data and check confirmation can be made, an entrance and exit gate is unlocked and the entrance and exit is permitted (steps n 21 to n 22 ). However, in the case where the check confirmation cannot be made even if the number reaches the previously determined check limit number of times, or in the case where the improper judgment result is obtained even if the personal identification key 19 or the card reader 20 is used, the improper judgment result is displayed on the check result display LED 16 and the restriction of entrance and exit is made (steps n 23 to n 24 ). In the correspondence of the present invention and the foregoing embodiment, the photograph means of the present invention corresponds to the camera 14 , 32 of the embodiment, and similarly in the following, the photograph object corresponds to the person being checked 31 , the button for check confirmation corresponds to the check start button 18 , the object detection sensor corresponds to the person detection sensor 15 , the memory means corresponds to the memory 43 or the registration file 51 and the display means corresponds to the check result display LED 16 and the check count display LED 17 . However, the present invention can be applied on the basis of the technical concept recited in the claims, and is not limited only to the structure of the foregoing embodiment. According to the present invention, even if a proper check image can not be obtained at the point of time when a button for check confirmation is pressed down, check confirmation can be made by using another image, so that it becomes unnecessary to repeatedly press down the button, and a check processing can be completed by one button press operation. It is appreciated that the image comparison apparatus is not limited to only checking a person, but include any object that is identifiable by photograph.	The present invention relates to an image comparison apparatus and method in which images are acquired using a photograph unit and comparing them with a registration of memorized images. The photograph unit acquires a plurality of images of the photograph object during a period from detection of the photograph object by the object detection sensor until a press of a button. After which, the acquired image is compared with previously memorized registration images and a comparison result indicating whether or not a match exists is outputted.	6
BACKGROUND OF THE INVENTION It has been conventional practice to support mine roofs with spaced support plates in order to prevent roof falls and roof fall accidents. Such support plates are generally held flush against the roof of the mine by long bolts or anchors that are inserted into bore holes drilled into the mine roof and fixed therein by mechanical or resin anchoring means. Where resin anchoring means are used to fix a bolt or rod that supports a mine roof support plate, usually a sleeve is inserted into the bore hole and a threaded bolt is threadedly engaged with the sleeve to support the plate. This has led to the use of various stop members on the bolts or anchors to enable initial rotation of the anchor to burst a resin cartridge previously inserted into the bore hole and enable mixing and setting of the resin to adhesively secure the anchor and a subsequent rotation of the rod to overcome the affect of the stop member, and thread the bolt into the anchor and pull the support plate flush against the mine roof. Such systems, where an anchor sleeve and bolt are both provided, require the formation and machining of dual complex parts and close tolerances between the coacting parts in order to effectively provide for meshing of the various parts and application of the correct torque to the bolt in order to assure safe and secure fixation of the support plate to the roof. Examples of such anchor and bolt systems are shown in U.S. Pat. Nos. 3,877,235, 4,023,373 and 4,122,681 which discuss the coaction of the bolt and anchor as well as the problems associated with, and the need for, strengthening of mine roofs. Some existing anchors comprise a concrete reinforcing bar having a head and flange on one end that is inserted into a bore hole and adhesively secured therein to support a plate. In another type of anchor bolt where no sleeve is required, a problem exists in assuring that the bolt will be firmly secured within a bore hole and also that the support plate will be fixed flush to the roof of the mine. For example, in U.S. Pat No. 3,940,941, a method for reinforcing roofs is disclosed wherein a metallic bolt is threaded at its lower end, and the upper end has a transverse cut at the top to form a pair of teeth to aid in piercing the resin packages. The threaded portion at the lower end of the bolt has a discontinuity therein so as to enable counterclockwise rotation of the bolt to advance the same into the bore hole and disperse the resin and fix the bolt in the bore hole, and clockwise rotation of a nut on the bolt to thread the nut upwardly and pull a washer carried thereon flush with the roof structure. A dual step operation is required to affix the washer flush with the mine roof, using counterclockwise and then clockwise rotation, and a depending portion of the threaded section remains exposed and extending downwardly from the roof, which could present a safety hazard in low roof areas of a mine. It is an object of the present invention to provide a unitary mine roof support plate bolt that does not require coaction or relative movement between parts of the bolt system. It is another object of the present invention to provide a mine roof support plate bolt that requires only a single operation to adhesively fix the bolt into a bore hole and fix a support plate flush with the roof surface. It is a further object of the present invention to provide a mine roof suppport plate bolt that assures adhesion of the upper section of the bolt within a bore hole by retention of resin adjacent that upper section during insertion and rotation of the bolt into the bore hole. It is an even further object of the present invention to provide a mine roof support plate bolt which will enable the use of the bolt in bore holes that may be slightly less in depth than that required to accept the bolt and enable pulling of the support plate flush with the mine roof. SUMMARY OF THE INVENTION A mine roof support plate bolt for use in resin anchoring of the bolt and cooperating support plate comprises an elongated metallic rod, such as a rebar, having a head at one end and a flange adjacent the head, and a groove formed in the other end of the rod, the groove forming opposed cutting edges at the end of the rod. A counterclockwise helical channel is formed in the rod at the section of the rod adjacent the groove, with the channel terminating in cooperative relationship with the groove. The cutting edges are formed by beveling the ends to the rod on opposite sides of the groove, and preferably the surface of the cutting edges so formed are at an acute angle to the plane normal to the axis of the rod. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view shown in elevation, illustrating the mine roof support plate bolt of the present invention upon insertion into a bore hole in a mine roof; FIG. 2 is a cross-sectional view as in FIG. 1 upon fixation of the mine roof support bolt in the bore hole by resin, showing the support plate in supporting position; and FIG. 3 is a cross-sectional view of the upper portion of a mine roof support bolt of the present assembly upon fixation of the bolt in a short bore hole. DETAILED DESCRIPTION The mine roof support plate bolt of the present invention provides for efficient and safe fixation of a support plate to a mine roof structure to provide support therefor. As illustrated in FIG. 1, the support bolt 1 comprises an elongated metallic rod 3 having surface irregularities such as ridges 5 about the surface of the rod. The rod is preferably the type of rod or bar used commercially in the reinforcement of concrete structures and is conventionally known as a "rebar." The rod has a head 7 at one end which may be in a square or other shape that is to be engaged with a tool for insertion of the rod into the bore hole, the head 7 preferably having a flange portion 9. At the other end of the rod from the head 7 there is a groove 11 formed in the rod, the groove leaving at the end of the rod two cutting edges 13. Formed in the rod, at the section thereof adjacent the groove, is a counterclockwise, helical channel 15. As illustrated, the channel 15, which is preferably an arcuate channel, terminates at the end of the rod in communication with the groove 11, the purpose of which is hereinafter explained, as shown at 17. In the use of the mine roof support plate bolt of the present invention, a bore hole 19 is first formed in the mine roof structure 21. As an example of the type of bore hole for use with a 7/8" rod, the hole would have a diameter of about 1', leaving a 1/16" clearance between the rod and wall of the bore hole. The length of the rod may vary but will generally be on the order of about 5 feet. The bore hole 19 has an end wall 23. The rod 3 is passed through an aperture in a support plate 25, such that the plate will rest on the flange 9 adjacent the head 7 of the bolt. Generally, such support plates are in the shape of a rectangle having a size of about 6" by 16", although the size may vary. A cartridge or capsule 27 of resin, commercially available, which may contain known epoxy or other resin material that requires mixing of two or more components in order to activate the resin and form an adhesive, is first inserted into the bore hole 19, followed by the end of the rod 3 having groove 11 therein. The support plate 25 is supported by the flange 9 at the outer end of the bolt carrying the head 7. Upon insertion of the cartridge 27 of resin to the end wall 23 of the bore hole 19, the rod is rotated in a clockwise direction, as indicated by the arrow in FIG. 1, and torque applied to the rod by a conventional tool (not shown). Upon application of the torque to the rod and forcing the rod further into the bore hole 19, the cutting edges 13 on the end of the rod will shred the cartridge, intimately mixing the adhesive components therein. As the adhesive 29 tends to run out of the bore hole 19 through the clearance between the rod 3 and the wall of the bore hole, the counterclockwise, helical channel 15 will partially restrain the downward flow of the adhesive and drive the same back towards the end of the bore hole, assuring good adhesive contact between the section adjacent the end of the rod 3 and the wall of the bore hole. When the support plate 25 is flush with the surface of the roof structure 21, the adhesive 29 will set, such adhesives generally setting in about a 15 to 20 second time period, with the head 7 and flange 9 of the rod fixing the support plate 25 to the surface to support the mine roof, as shown in FIG. 2. The cutting edges 13, formed by cutting the groove 11 in the end of the rod 3, are beveled as at 31, with a beveled surface of about 15°, from the surface of the rod to the groove, being preferred. A preferred embodiment for use with a 7/8" diameter rebar provides that the groove 11 be about 1/2" wide and between 1/2" to 3/4" deep in the end of the rod. The use of the groove 11 and cutting edges 13 on the end of the rod 3 enables the use of the rod even where the bore hole is of a slightly less depth than that required to bring the support plate carried by the rod flush with the roof surface of the roof structure. As illustrated in FIG. 3, the cutting edges 13 on the end of the rod will act as a drill to deepen the hole by forming a supplemental bore hole 33 in the end wall 23 of initial bore hole 19, the supplemental bore hole 33 having its own end wall 35. To assist in the drilling of the supplemental hole 33 when required, the surface 37 of the cutting edge 13 is angled, with an acute angle indicated as angle α in FIG. 3 provided. Preferably, an acute angle of about 2° to the plane normal to the axis of the rod is provided. Each cutting surface has such an angle with the slope of the angle on one such surface opposite the slope on the other surface. The grindings from formation of the supplemental hole 33 will thus be concentrated in the groove 11 and will not interfere with setup of the resin 29 and good adhesion between the adhesive, rod and bore hole wall. The present mine roof support plate bolt is also usable where some breakage or separation of the roof structure has occurred due to the ability of the grooved and channeled end of the rod to pump resin upwardly into the bore hole. In such instances, a plurality of cartridges of resin may be inserted into the bore hole and the grooved section of the rod, upon rotation of the rod, will disperse the adhesive formed from the resin upwardly into the bore hole and throughout the upper region thereof to provide adhesion through the structure. The present mine roof support plate bolt provides an efficient and economical means for supporting the roof support plate flush with the surface of the mine roof while enabling the use of the bolt with bore holes which may be slightly shorter than necessary to accept the bolt. Previously, if the bore hole was slightly short and the plate could not be pulled flush against the roof surface, the operation had to be repeated. The cutting edges and groove of the present bolt enable drilling of a supplementary bore hole the width of the rod with grindings or cuttings from the end wall of the initial bore hole directed into the groove so as not to interfere with good adhesion of the rod with the wall of the roof structure.	A mine roof support plate bolt formed from a concrete reinforcing rod has a head and flange at one end and a groove at the other end thereof, the groove forming opposed cutting edges at that end of the rod, and a counterclockwise, arcuate, helical channel in the section of the rod adjacent said other end, the counterclockwise, helical channel communicating with the groove, such that good mixing of resin adapted to secure the bolt in a bore hole is effected, while the cutting edges enable lengthening of the bore hole in instances where the rod would otherwise not pull the support plate flush with the roof structure.	4
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a ceramics material (or member) and a method of producing it, and more particularly to a ceramics material that shows an excellent plasma-resistant property in an atmosphere of a halogen corrosive gas and also excellent mechanical property, and a method of producing it. 2. Description of the Related Art Generally, a process of manufacturing a semiconductor device uses an etching apparatus or sputtering apparatus for subjecting a semiconductor wafer to micromachining, or a CVD apparatus for depositing a film on the semiconductor wafer. These apparatus are provided with a plasma generating mechanism for the purpose of high integration. For example, a helicon wave plasma etching device whose schematic is shown in FIG. 2 is known. In FIG. 2, reference numeral 1 denotes a processing chamber which is provided with an antenna 2 , an electromagnet 3 and a permanent magnet 4 on the periphery. The processing chamber 1 includes an etching gas supplying inlet 5 and a vacuum discharge outlet 6 , and also a lower electrode 8 for supporting a semiconductor wafer, which is installed within the chamber. The antenna 2 is connected to a first high frequency power source 10 through a first matching network 9 and connected to a second high frequency power source 12 through a matching network. Etching by the etching apparatus described above will be carried out as follows. First, with the semiconductor wafer 7 placed on the lower electrode 8 , after the interior of the processing chamber 1 has been evacuated, an etching gas is supplied. Next, the antenna 2 and lower electrode 8 are supplied with high-frequency currents at a frequency of 13.56 MHz from the high frequency power sources 10 and 12 through the corresponding matching networks 9 and 11 . On the other hand, the electromagnet 3 is also supplied with a current so that a high density plasma is generated within the processing chamber. The plasma energy thus formed decomposes the above etching gas in an atomic state. Thus, the film formed on the upper surface of the semiconductor wafer is etched. Meanwhile, these apparatus uses as an etching gas a corrosive gas such as a chloric gas inclusive of boron chloride (BCl 3 ) or carbon fluoride (CF 4 ). Therefore, the members exposed to plasma in the atmosphere of the corrosive gas, such as an inner wall of the processing chamber 1 , a monitoring window, a microwave introducing window and a lower electrode 8 are required to have a plasma-resistant property. In order to satisfy the above requirement, a ceramics material such as a sintered body of alumina, of sodium nitride, of aluminum nitride, etc. has been used as the plasma resistant material. However, the ceramics material such as the sintered body of alumina, of sodium nitride, of aluminum nitride, etc. gradually corrodes when it is exposed to the plasma in the atmosphere of the corrosive gas. As a result, the crystal particles constituting the surface are separated so that “particle pollution” is produced. Specifically, the separated particles deposited on the semiconductor wafer 7 and the lower electrode 8 adversely affect the quality and accuracy of the deposited film. This presents a problem of deteriorating the performance and reliability of the semiconductor device. In the CVD apparatus also, since the above ceramics material is exposed to a fluorine gas such as fluorine nitride (NF 3 ) under the plasma during the cleaning, it is required to have corrosion resistance. In order to obviate the problem of corrosion resistance, a ceramics material containing a sintered body of yttrium-aluminum-garnet (YAG) as a raw material has been proposed (JP-A- 10-236871 ). Namely, the proposed ceramics material is a material in which the surface exposed to the plasma in the atmosphere of a halogenic corrosive gas is formed of the sintered body of YAG and has a center line average height (Ra) of 1 μm or less. However, the sintered body of YAG is excellent in the plasma resistance, but inferior in the mechanical property such as bending strength and breakage toughness. The inferior mechanical property (e.g. fragileness) means that the material is apt to be damaged or broken during a process of cleaning. Being coupled with relative high cost of the material itself, this leads to an increase in the production cost of the manufacturing apparatus or semiconductor. SUMMARY OF THE INVENTION This invention has been accomplished under the above circumstance, and intends to provide a low-cost ceramics material which has high plasma resistance and is also excellent in the mechanical property such as bending strength and breakage toughness, and a method of producing it. The first aspect of this invention is a ceramics material characterized by comprising a base material substantially made of a sintered body of alumina and a yttrium-aluminum-garnet(YAG) layer having a thickness of 2 μm or more which is formed on a surface of the base material. A ceramics material according to the second aspect of this invention, is characterized in that the surface of the base material is covered with the YAG layer so that alumina crystalline particles in the sintered body of alumina are not exposed. A ceramics material according to the third aspect of this invention is characterized in that the YAG layer has a thickness of 150 μm or less. A ceramics material according to the fourth aspect of this invention is characterized in that the base material is a sintered body of alumina with an amount of YAG which increases gradually from the interior to the surface. A ceramics material according to the fifth aspect of this invention is characterized in that an amount of YAG within the sintered body of alumina is 5 weight % or less. A ceramics material according to the sixth aspect of this invention is characterized in that the alumina crystalline particles in the sintered body of alumina have an average crystalline diameter of 200 μm. The seventh aspect of this invention is a method of producing a ceramics material comprising the steps of: preparing a raw powder in which alumina particles having an average particle diameter of 0.1-1.0 μm are mixed with at least a magnesium compound of 0.01-1 weight % in magnesia and an yttrium compound of 0.1-15 weight % in yttria; molding the raw powder and calcining a molding thus formed; and heating the molding in an atmosphere containing a hydrogen gas to form YAG which is exuded to the surface to deposit YAG on the surface and sintering the molding. The eighth aspect of this invention is characterized in that a solution of yttrium is added as a component of the raw powder after the molding has been calcined. The ninth aspect of this invention is characterized in that a layer of YAG exuded to and deposited on the surface of the sintered molding is heated so that it is densified. The tenth aspect of this invention producingis characterized in that a layer of YAG exuded to and deposited on the surface of the sintered molding is heated so that it is molten, and solidified again. The eleventh aspect of this invention is a method of producing a ceramics material, characterized in that a powder layer, molding or a calcined body of YAG is laminated on a molding or a calcined body of alumina containing magnesium and yttrium and is heated in an atmosphere of a hydrogen gas. The twelfth aspect of this invention is a method of producing a ceramics material, characterized in that a powder layer, molding or a calcined body of YAG is laminated on the surface of a sintered body with a YAG layer deposited thereon and is heated in an atmosphere of a hydrogen gas so that it is sintered. In these aspects of this invention, it seems that the surface of the base material of alumina substantially made of a sintered body of alumina is covered with the YAG layer through its exuding for the following matters. The yttrium component which resides on the surface of the alumina raw particle is deformed into YAG through heating, and the boundary among the alumina particles is decreased owing to the growth of the alumina particle. As a result, the YAG cannot reside at the center of the sintered body of alumina so that the major amount of it gradually move to the surface of the sintered body. In this inventions, the YAG layer covering the surface of the base material of alumina is required to have a thickness of 2 μm or more. Specifically, where the thickness is shorter than 2 μm required plasma resistance cannot be given. Further, the surface of the base material of alumina is preferably covered with the YAG layer so that the base material of alumina is not exposed to the surface. Where the base material of alumina is exposed, when the YAG layer is exposed to plasma in an atmosphere of a corrosive gas, the exposed portion of the base material will partially corrode so that fine particles are apt to occur. Furthermore, the thickness of the YAG layer is preferably not greater than 150 μm. The thickness exceeding 150 μm does not provide an improvement of the effect, but is a hindrance of low production cost. The base material substantially made of a sintered body of alumina means that the main component of the base material is the sintered body of alumina. Particularly, it is preferably the sintered body in which the composition of alumina is 85 weight % or more. Further, where the YAG layer is formed as a coating through breaching when the alumina is sintered, the ceramics material can exhibit plasma resistance and a mechanical property. In the structure in which the surface of the base material of alumina is covered with the YAG layer, where the base material of alumina is a sintered body of alumina with an amount of YAG which increases gradually from the interior to the surface, a difference in the thermal expansion coefficient between the base material of alumina and YAG layer is reduced. Therefore, a ceramics material with improved separation resistance during the heating cycle is provided. The amount of YAG in the interior of the sintered body of alumina is preferably 5 weight % or less in order to provide the ceramics material with higher breakage toughness, more preferably 3 weight % or less. In the case of the ceramics material of which the entire outer surface is covered with the YAG layer, the interior of the base material of alumina refers to the vicinity of center of gravity. Incidentally, the member which is obtained by optionally cutting the ceramics material with the entire outer surface covered with the YAG layer in order to give plasma resistance to a specific plane of the base material should be also included in the category of the ceramics material herein referred to. The average particle diameter of the sintered crystal in the base material of alumina (sintered body of alumina) is preferably 200 μm or less, more preferably 5-200 μm, and much preferably 10-40μm. If the average particle diameter exceeds 200 μm, it is difficult to disperse uniformly gradually the amount of YAG which increases gradually from the interior of the sintered body of alumina to the surface. Namely, YAG is apt to reside locally. This make it difficult to provide higher separation resistance during the heating cycle of the YAG layer. The particle diameter is a value measured by the planimetric technique. In the sintering step of the ceramics material, where the YAG layer is formed through exuding on the surface of the base material of alumina, magnesia (which can be replaced by the hydrate of magnesium sulfate and magnesium nitrate) of 0.01-1 weight % is preferably added to control the growth of crystalline particles. The ceramics material in this invention can be produced by the method defined in this invention. Generally, a raw powder is prepared in which alumina particles having an average particle diameter of 0.1-1.0 μm are mixed with at least a magnesium compound of 0.01-1 weight % in magnesia and an yttrium compound of 0.1-15 weight % in yttria. After the raw powder has been granulated, it is molded by e.g. hydrostatic pressure press, and the molding thus formed is subjected to calcination processing. The molding thus obtained is heated in an atmosphere containing a hydrogen gas to form YAG which is exuded to the surface through the grain growth of alumina to make a YAG film. The molding is further sintered to provide a desired ceramics easily. Incidentally, the granulated raw power may be molded by not the hydrostatic pressure press but may be molded by other molding means such as extrusion, injection molding, casting, etc. Further, when the raw powder may be prepared, in place of making particles as the solution containing yttrium, yttrium or its compound particles (powder) is added/mixed as long as it can be uniformly scattered. The average particle diameter of the alumina particle which is the main component of the raw powder is preferably selected in a range of 0.1-1.0 μm. This is because the crystalline particle of alumina makes abnormal growth during a final sintering step, which may ruin the exuding of YAG to the surface and its deposition. The addition of magnesia is done in order to control appropriately the crystalline particles of the sintered body which is the base material having the alumina as a main component. The composition ratio is selected in a range of 0.01-1 weight %. Incidentally, the composition of magnesia to be added/mixed may be a magnesium compound which is deformed into magnesia by heating such as magnesium sulfate, magnesium nitrate, etc. In this case, its adding/mixing amount should be selected in a range of 0.01-1 weight %. The addition of the solution containing yttrium is efficient to generate required YAG which is exuded to and deposited on the surface of the sintered body of alumina and improve plasma-resistance. It is selected to be 0.1-15 weight % in yttria. It should be noted that the solution containing yttrium is obtained by dissolving one or two or more of yttrium acetate, yttrium chloride, or their hydrate in pure water, alcohol, etc. In this invention, the raw powder containing the alumina particles as a main component is mixed/stirred with magnesia, yttrium composition, binder resin and medium solution to prepare a slurry. This is carried out using e.g. a rotary ball milling. The slurry thus prepared is granulated using e.g. a spray drier. The granulated powder is molded by an ordinary pressuring molding such as hydrostatic press, extrusion, injection molding, or casting. The molding of the granulated powder is calcined at a temperature of 600-1300° C. under an atmospheric pressure. The temperature and time of the calcination is determined according to the shape and size of the molding. The sintering after the calcination is carried out at a temperature of 1700-1850° C. in an atmosphere containing a hydrogen gas such as a hydrogen current. In this case, in order to form YAG more smoothly and advance its exuding to and deposition on the surface while suppressing the abrupt growth of crystal particles, the temperature rising speed is selected and set at a slightly slow speed, or the sintering time is set at a longer time. In this invention, the YAG formed during the calcination and sintering step and exuded and deposited on the surface is heated for the purpose of densifying by the YAG layer. Specifically, where the YAG film exuded to and deposited on the surface of the sintered body is thin or coarse, it is heated at the temperature of e.g. 1700° C.-1850° C. Thus, the YAG exuded to and deposited on the surface is softened and dissolved again, thereby improving plasma-resistance. The ceramics material can be produced in the following process. In this invention, a molding or a calcined body of alumina containing magnesium and yttrium is prepared, and a powder layer, molding or a calcined body of YAG is laminated on the surface of the molding or calcined body thus prepared. The laminated body is heated in an atmosphere of a hydrogen gas so that it is sintered. Otherwise, a powder layer, molding or a calcined body of YAG is laminated on the surface of the sintered body with a YAG layer deposited thereon. The laminated body is heated in an atmosphere of a hydrogen gas so that it is sintered. In this inventions, a structure is adopted in which a base material is substantially made of an sintered body of alumina and the surface thereof is covered with a YAG layer. Specifically, the structure is adopted in which the base material is made of an sintered body of alumina with an excellent mechanical property such as bending strength and breakage toughness while the surface exposed to plasma is covered with the YAG layer with excellent plasma-resistance. Where the base material is an sintered body of alumina with an amount of YAG which increases gradually from the interior to the surface, it exhibits high heat-resistance. The coverage of the YAG layer improves the plasma resistance of the ceramics material, and cancels the occurrence of damage/breakage during the cleaning. Thus, the ceramics material which is free from the fear of particle contamination and has excellent heating-cycle resistance can be acquired. Therefore, this invention suppresses the increase in the production cost of a producing apparatus and semiconductor and also efficiently contributes to the production/processing of the semiconductor with high performance and reliability without adversely affecting the quality and accuracy of the deposited film. This invention can provide, with high yield and in mass production, a ceramics material in which the base material is made of a sintered body of alumina with an excellent mechanical property such as bending strength and breakage toughness while the surface exposed to plasma is covered with the YAG layer with excellent plasma-resistance. Particularly, this invention can easily adopt the structure in which the YAG is exuded to and deposited on the surface of the base material of the sintered body of alumina with an amount of YAG which increases gradually from the interior to the surface, and so can provide a ceramics material with excellent thermal shock resistance. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a reflected electronic image of a cut plane of a plasma-resistant material according to an embodiment of this invention. FIG. 2 shows a sectional view of a schematic configuration of a CVD apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an explanation will be given of various embodiments of this invention. Embodiment 1 An appropriate amount of ion-exchanging water and 2 parts of polyvinyl alcohol were added to a composition system of MgSO 4 .7H 2 O of 750 ppm in magnesia and Y(CH 3 COO) 3 .4H 2 O of 1.5 weight parts in yttria for 100 weight parts of alumina particles having an average particle diameter of 0.3μm. The solution is stirred to mix these components, thereby preparing a slurry. The slurry is granulated using a spray drier. The granulated powder was molded under the pressure of 10 MPa using hydrostatic pressure press (CIP) into a molding having a thickness of 10 mm and a width of 100 mm and a length of 100 mm. The molding was calcined at the temperature of 900° C. in the air and sintered at the temperature of 1790° C. in an atmosphere of a hydrogen gas, thereby making a ceramics material. The ceramics material was identified by the X-ray diffraction (XRD). As a result, YAG other than alumina existed on the surface and in the interior of the sintered body (ceramics material). As a result of observation/image pick-up of a section of the sintered body by an electron microscope, as seen from an inverted electronic image shown in FIG. 1, it was confirmed that the sintered body at issue is the ceramics material with the entire surface of the base material which is substantially made of the sintered body of alumina is covered with the YAG layer. In FIG. 1, a white portion represents a particle layer of YAG crystal, and a black portion represents alumina crystal particles. Section A denotes the YAG layer and section B denotes the base material substantially made of the sintered body of alumina. Incidentally, it was confirmed that the amount of YAG increases gradually from the interior (lower portion) of the base material to the surface (upper portion). It was also confirmed that the surface of the base material is covered with the YAG layer having a thickness of 20-30 μm so that the exposed portion of the alumina crystal particles (sintered body) do exist on the surface. The average particle diameter of the alumina crystal particles measured for the above inverted electronic image by the planimetric technique was 20 μm. Further, the material cut out from the interior of the base material (center portion) was subjected to ICP light emission analysis to measure the amount of YAG. The result was 0 weight %. The sample pieces of 10×10 mm square were cut out from the above sintered body and their breakage toughness were measured by the IF method using a Vickers indenter. The result was 4.0 MPa.m ½ which is approximately equal to the breakage toughness of the sintered body of alumina. The three-point bending strength measured for these samples was 350 MPa. Incidentally, the sintered body of YAG, which has a breakage toughness of 1-2MPa.m ½ and a three-point bending strength of 200-300 MPa, is fragile. The sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 10×l0 mm square were cut out from the above sinter and attached to a parallel plate type RIE apparatus. The sample pieces were subjected to a plasma exposure test under the condition of a frequency of 13.56 MHz, a high frequency source of 500, a high frequency bias of 300 W, CF 4 /O 2 /Ar=30:20:50, and a gas pressure of 0.6665 Pa (5 m Torr). The result of etching rate (nm/Hr) was 1 or less. Ten sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 20×20 mm square were cut out from the above sintered body. These samples were subjected to 100 times of heat cycles in which they are held for ten minutes in an air furnace kept at 400° C. and taken out to the furnace and cooled down to the room temperature. As a result of the heat cycles, it was confirmed that the layer of YAG layer has not been separated. In other words, because the dense YAG layer on the surface and the base material of alumina are integrated through a portion with the amount of YAG which increases gradually from the interior of the base material of alumina to the surface, the above samples exhibit excellent heat cycle resistance. The excellent heat cycle resistance means sufficient endurance to the heat cycle by e.g. plasma radiation. Embodiment 2 An appropriate amount of ion-exchanging water and 2 parts of polyvinyl alcohol were added to a composition system of MgSO 4 .7H 2 O of 750 ppm in magnesia and Y(CH 3 COO) 3 .4H 2 O of 3 weight parts in yttria for 100 weight parts of alumina particles having an average particle diameter of 0.3 μpm. The solution is stirred to mix these components, thereby preparing four kinds of slurries. Each slurry is granulated using a spray drier. The granulated powder is molded under the pressure of 100 MPa using hydrostatic pressure press (CIP) into a molding having a thickness of 10 mm and a width of 100 mm and a length of 100 mm. The molding was calcined at the temperature of 900° C. in the air and sintered at the temperature of 1790° C. in an atmosphere of a hydrogen gas, thereby making a ceramics material. The ceramics material was identified by the X-ray diffraction (XRD). As a result, it was confirmed YAG other than alumina exists on the surface and in the interior of the sintered body(ceramics material). Specifically, as a result of observation/image pick-up of a section of the sintered body by an electron microscope, as in the case of the first embodiment, it was confirmed that the sintered body at issue is the ceramics material with the entire surface of the base material which is substantially made of the sintered body of alumina is covered with the YAG layer. As regards the ceramics material, it is confirmed that the amount of YAG increases gradually from the interior Lower portion) of the base material to the surface (upper portion). It was also confirmed that the surface of the base material is covered with the YAG layer having a thickness of 20-70 μm so that the exposed portion of the alumina crystal particles (sintered body) do exist on the surface. The average particle diameter of the alumina crystal particles measured for the above inverted electronic image by the planimetric technique was 20 μm. Further, the material cut out from the interior of the base material (center portion) was subjected to ICP light emission analysis to measure the amount of YAG. The result was 0.5 weight %. The sample piece of 10×10 mm square was cut out from the above sintered body and its breakage toughness was measured by the IF method using a Vickers indenter. The result was 3.9 MPa.m ½ which is approximately equal to the breakage toughness of the sintered body of alumina. The three-point bending strength measured for these samples was 340 MPa. The sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 10×10 mm square were cut out from the above sintered body and were subjected to a plasma exposure test under the same condition as in the first embodiment. The result of etching rate (nm/Hr) was 1 or less for any sample. Further, ten sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 20×20 mm square were cut out from the above sintered body. These samples were subjected to 100 times of heat cycles in which they are held for ten minutes in an air furnace kept at 400° C. and taken out to the furnace and cooled down to the room temperature. As a result of the heat cycles, it was confirmed that the layer of YAG layer has not been separated. In other words, because the dense YAG layer on the surface and the base material of alumina are integrated through a portion with the amount of YAG which increases gradually from the interior of the base material of alumina to the surface, the above samples exhibited excellent heat cycle resistance. Embodiment 3 An appropriate amount of ion-exchanging water and 2 parts of polyvinyl alcohol were added to a composition system of 0.1 weight part of silica particles having an average particle diameter of 0.3 μm, MgSO 4 .7H 2 O of 750 ppm in magnesia and Y(CH 3 COO) 3 .4H 2 O of 5.0 weight parts in yttria for 100 weight parts of alumina particles having an average particle diameter of 0.3 μm. The solution was stirred to mix these components, thereby preparing a slurry. The slurry was granulated using a spray drier. The granulated powder was molded under the pressure of 100 MPa using hydrostatic pressure press (CIP) into a molding having a thickness of 10 mm and a width of 100 mm and a length of 100 mm. The molding was calcined at the temperature of 900° C. in the air and sintered at the temperature of 1790° C. in an atmosphere of a hydrogen gas, thereby making a ceramics material. The ceramics material was identified by the X-ray diffraction (XRD). As a result, it was confirmed that YAG other than alumina exists on the surface and in the interior of the sintered body (ceramics material). Specifically, as a result of observation/image pick-up of a section of the sintered body by an electron microscope, as in the case of the first embodiment, it was confirmed that the sintered body at issue is the ceramics material with the entire surface of the base material which is substantially made of the sintered body of alumina is covered with the YAG layer. Incidentally, it was confirmed that the amount of YAG increases gradually from the interior (lower portion) of the base material to the surface (upper portion). It was also confirmed that the surface of the base material is covered with the YAG layer having a thickness of 5-50 μm so that the exposed portion of the alumina crystal particles (sintered body) do exist on the surface. The average particle diameter of the alumina crystal particles measured for the above inverted electronic image by the planimetric technique was 20 μm. Further, the material cut out from the interior of the base material (center portion) was subjected to ICP light emission analysis to measure the amount of YAG. The measured amount was 0.8 weight %. The sample pieces of 10×10 mm square were cut out from the above sintered body and their breakage toughness were measured by the IF method using a Vickers indenter. The result was 3.9 MPa.m ½ which is approximately equal to the breakage toughness of the sintered body of alumina. The three-point bending strength measured for these samples was 340 MPa. The sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 10×10 mm square were cut out from the above sintered body, and were subjected to a plasma exposure test under the same condition as in the first embodiment. The result of etching rate (nm/Hr) was 1 or less for any sample. Further, ten sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 20×20 mm square were cut out from the above sintered body and subjected to 100 times of heat cycles under the same condition as in the first embodiment. As a result, it was confirmed that the layer of YAG layer has not been separated. In other words, because the dense YAG layer on the surface and the base material of alumina are integrated through a portion with the amount of YAG which increases gradually from the interior of the base material of alumina to the surface, the above samples exhibit excellent heat cycle resistance. Embodiment 4 An appropriate amount of ion-exchanging water and 2 parts of polyvinyl alcohol were added to a composition system of MgSO 4 .7H 2 O of 750 ppm in magnesia for 100 weight parts of alumina particles having an average particle diameter of 0.03 μm. The solution was stirred to mix these components, thereby perparing a slurry. The slurry is granulated using a spray drier. The granulated powder was molded under the pressure of 10 MPA using hydrostatic pressure press (CIP) into a molding having a thickness of 10 mm and a width of 100 mm and a length of 100 mm. On the other hand, an appropriate amount of ion-exchanging water was added to a composition system of 0.5 weight part of a dispersing agent of polycarboxylic acid ammonium for 100 weight parts of alumina particles having an average particle diameter of 0.8 μm. The solution was stirred to mix the above components, thereby preparing another slurry. The above YAG slurry was applied to the entire surface of the molding of alumina. The molding was dried in a drier at the temperature of 40° C. The molding was calcined at the temperature of 900° C. and sintered at the temperature of 1790° C. in an atmosphere of a hydrogen gas, thereby making a ceramics material. The ceramics material was identified by the X-ray diffraction (XRD). As a result, it was confirmed that YAG other than alumina does not exist on the surface and in the interior of the sintered body (ceramics material). Specifically, as a result of observation/image pick-up of a section of the sintered body by an electron microscope, it was confirmed that the sintered body at issue is the ceramics material with the entire surface of the base material which is substantially made of the sintered body of alumina is covered with the YAG layer having a thickness of 20-30 μm. The average particle diameter of the alumina crystal particles measured for the above inverted electronic image by the planimetric technique was 20 μm. Further, the material cut out from the interior of the base material (center portion) was subjected to ICP light emission analysis to measure the amount of YAG. The result was 0 weight %. The sample pieces of 10×10 mm square were cut out from the above sintered body and their breakage toughness were measured by the IF method using a Vickers indenter. The result was 4.1 MPa.m ½ which is approximately equal to the breakage toughness of the sintered body of alumina. The three-point bending strength measured for these samples was 360 MPa. The sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 10×10 mm square were cut out from the above sintered body and were subjected to a plasma exposure test under the same condition as that in the first embodiment The result of etching rate (nm/Hr) was 1 or less. Further, ten sample pieces with the one side being the surface of the sintered body itself having a thickness of 2 mm and an area of 20×20 mm square were cut out from the above sintered body. These samples were subjected to the heat cycle test under the same condition as in the first embodiment. Before the number of the heat cycles reaches 100 times, the local separation of the YAG layer was confirmed for three of the ten samples. Incidentally, the ceramics material having the same property as described above can be acquired as follows. A molding or calcined body having a composition system of the alumina granulated powder with magnesium and yttrium contained therein. is prepared. Another molding or calcined body is laminated on surface of the prepared molding or calcined body. The laminating structure is sintered in an atmosphere containing hydrogen. Otherwise, the ceramics material according to the first or second embodiment, i.e. the sintered body of alumina with the YAG layer formed on the surface thereof is prepared as a base material. A powder layer, molding or calcined body of YAG is laminated again on the surface of the base material. The laminating structure is sintered in an atmosphere containing hydrogen. Comparative Examples 1 and 2 In the first embodiment, alumina particles having an average particle diameter of 0.2 μm were used in place of the alumina particles having an average particle diameter of 0.3 μm and the calcined body was sintered at the temperature of 1760° C. (Comparative Example 1). The composition of Y(CH 3 COO) 3 .4H 2 O was set for 20 weight parts instead of 1.5 weight parts in yttria, and the calcined body was sintered at the temperature of 1770° C. (Comparative Example 2). Two kinds of ceramics materials were prepared on the same condition as in the first embodiment except the above condition. Under the same condition as in the first embodiment, these ceramics materials were subjected to various tests inclusive of identification of the property and thickness of the YAG layer formed on the surface of the alumina base material by the X-ray diffraction (XRD), measurement of the average particle diameter of the alumina crystal particles, confirmation of the changing tendency of the amount of YAG from the interior (lower portion) of the base material to the surface thereof (upper portion), measurement of the amount of YAG in the interior (central portion) of the base material, measurement of the breakage toughness and three-point bending strength, plasma exposure test, heat cycle test, etc. In the case of the first comparative example, the following matters were confirmed. The YAG layer was not uniformly formed on the surface so that the exposed area of the alumina crystal particles is 60% in a ratio of the entire area. The average particle diameter of the alumina particle was 3 μm. The amount of YAG in the interior (central portion) of the base material was 1 weight %. The amount of YAG was changed gradually from the interior of the base material of alumina to the surface. The breakage toughness of 3.5 MPa.m ½ and the three-point bending strength of 350 MPa were measured. The local presence of portions of the etching rate of 10 by the plasma exposure test was confirmed. The heat cycle test could not be carried out. On the other hand, in the case of the second comparative example, the following matters were confirmed. The surface was covered with the YAG layer having a thickness of 80-120 μm. The average particle diameter of the alumina crystal particles was 20 μm. The amount of YAG in the interior (central portion) of the base material was 8 weight %. The mount of YAG was changed gradually from the interior of the base material of alumina to the surface thereof. The breakage toughness of 3.5 MPa.m ½ and the three-point bending strength of 280 MPa were measured. The etching rate by the plasma exposure test was 1 or less. The heat cycle test of 100 times could be carried out. This invention should not be limited to the embodiments described above, but can be changed in various modifications without departing from the scope and sprit of the invention. For example, the base material of alumina may be a sintered body containing alumina. Further, the kind of sintering aids to be added and its composition ratio can be optionally selected in accordance with the use and using purpose of the ceramics material. In this inventions, a structure is adopted in which the base material is made of a sintered body of alumina with an excellent mechanical property such as bending strength and breakage toughness while the surface is covered with the YAG layer with excellent plasma-resistance. Such a structure cancels the occurrence of damage/breakage during the cleaning, and removes the fear of particle contamination. Namely, this invention can suppress the increase in the production cost of a producing apparatus and semiconductor and also provides a ceramics material which efficiently contributes to the production/processing of the semiconductor with high performance and reliability without adversely affecting the quality and accuracy of the deposited film. Particularly, the structure in which a composite layer is interposed between the base material of alumina and the YAG layer exhibits excellent heat-cycle resistance so that it can be suitably applied to the application in which heating and cooling are repeated. Further, this invention can provide, with high yield and in mass production, a ceramics material which has an excellent mechanical property such as bending strength and breakage toughness and excellent plasma-resistance and suitable to the apparatus for manufacturing semiconductor.	The invention is a method of producing a ceramics material comprising the steps of: preparing a raw powder in which alumina particles having an average particle diameter of 0.1-1.0 μare doped with at least magnesia of 0.01-1 weight % and a solution containing yttrium of 0.1-15 weight % in yttria; molding said raw powder and calcining a molding thus created; and heating the calcined molding in an atmosphere containing a hydrogen gas to create YAG which is leached to the surface to deposit YAG on the surface and sintering the molding.	2
FIELD OF THE INVENTION This invention relates generally to article-holding devices and especially to a carrier for a beverage container or the like. In particular, the carrier of this invention concerns an auxiliary support attachable to the interior of a vehicle. BACKGROUND OF THE INVENTION The prior art is profuse on the subject of cupholders for vehicles. In the advancement of the art, the overriding problem of beverage stability in a moving environment has been addressed in a variety of ways and with a variety of devices, having progressed to door-securable types, adjustable as to interior door thickness accommodation, container-confinement diameters and upright holder positioning. For example, the device of U.S. Pat. No. 4,767,092 used deployment of one or more arm-stiffeners and rather complexly constructed container-confinement means. The device of U.S. Pat. No. 4,727,890 did not deal with diameter adjustability. U.S. Pat. No. 4,655,425 used a resilient pusher element to counter shake, rattle and roll. The device of U.S. Pat. No. 4,634,089 required an adhesively-attached fixture to the vehicle interior. Still absent has been a simple, releasably attachable device, now provided by the instant invention, which device may be clampingly securable to vehicle doors of different interior thicknesses and provide a singly adaptable means for both selective diameter adjustability and selectively adjustable vertical positioning of a container-confining holder. SUMMARY OF THE INVENTION Briefly, the device of this invention generally concerns a carrier for a beverage container for attachment to a vehicle door. The carrier includes an insert portion, a support portion for a container-holder and a holder. A feature of the invention is in the provision of a simply designed support means providing both selective adjustability of the holder diameter for container confinement and selectively adjustable vertical positioning of the holder. The invention also encompasses a carrier that is releasably clampingly attachable to a vehicle door providing taut engagement for enhanced carrier stability. Although the invention visualizes the use of a resilient plastic material for the various embodiments, it should be noted that other materials or combinations of materials may be used, including resiliently deformable sheet metal as shown in a particular embodiment. The invention also provides for the accommodation of door interiors ranging in thickness. Having thus summarized the invention, it will be seen that it is an object of this invention to provide a carrier for a beverage container of the general character described herein, which contains novel features and is not subject to the aforementioned deficiencies. Specifically, it is an object of this invention to provide a carrier for a beverage container for releasable securement to a vehicle door. Another object of the invention is to provide a carrier for a beverage container that has a selectively diameter-adjustable holder for closely conforming container confinement. Another object of the invention is to provide a carrier for a beverage container wherein the holder is vertically selectively adjustably positionable. Still another object of this invention is to provide a carrier for a beverage container that is adaptable for accommodating vehicle doors of ranging interior thicknesses. A further object of this invention is to provide a carrier for a beverage container that is clampingly attachable to a vehicle door for enhancing carrier stability. A still further object of this invention is to provide a carrier for a beverage container which is simple in construction, low in cost, reliable in use and well adapted for mass production and fabrication techniques. Other objects in part will become apparent and in part pointed out hereinafter. With these ends in view, the invention finds embodiments in certain combinations of elements and arrangements of parts which the aforementioned objects and certain other objects are hereinafter attained, all as fully described with reference to the accompanying drawings and the scope of which is more particularly pointed out and indicated in the appended claims. DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a carrier for a beverage container in accordance with the invention. FIG. 2 is an exploded perspective view of FIG. 1. FIG. 3 is a sectional view along line 3--3 of FIG. 1 of the carrier mounted on a vehicle door, showing an insert portion engaged within a window slot opening, an inverted V-shaped portion circumscribing interior weatherstripping, a support portion including interconnected slots and tabs supporting a holder in an upright position. FIG. 3A is an auxiliary sectional view along line 3--3 of FIG. 1 showing the carrier of FIG. 3 with the support portion displaced accommodating a thicker door interior in clamping relationship and the relocation of the holder uprightly positioned in a lower tier of slots. FIG. 4 is a perspective view of an alternate embodiment of the carrier of the invention showing a selectively horizontally and vertically attachable recessed holder snap-interfittingly engaged with the support portion. FIG. 5 is a perspective view of another alternate embodiment of the carrier of the invention showing a horizontally diameter-adjustable two-sectioned longitudinally integrated holder. FIG. 6 is a top view of FIG. 5 showing the horizontally diameter-adjustable feature. FIG. 7 is another embodiment of the invention in perspective view illustrating a corrugated resiliently reformable support portion. FIG. 8 is another embodiment of the invention in a exploded perspective view showing a coin-tray-article holder with a hooked cooperative connecting portion and a support portion including one longitudinal column of interconnection slots. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to the invention, the reference numeral 20 denotes generally a carrier for a beverage container in accordance with the invention. The carrier 20 as shown in FIGS. 1 and 2 is comprised of an insert portion 22, a support portion 24 for a holder and a container-confining holder 26. The carrier 20 may be fabricated of plastic, sheet metal, wire, cardboard or other resilient, deformable or supple materials or in hybrid constructions of combinations of such materials in accordance with the invention. As can be seen in FIGS. 3 and 3A, the carrier 20 is designed to be mounted to the interior portion 28, 56 of a vehicle door 29, the insert portion 22 extending downwardly in wedging frictional contact within the window slot opening 30 between the window 31 and/or contiguous weatherstripping 34. An inverted V-shaped portion 32 is atypically high-rising, intended for providing clearance for unskewed mounting over the high-rise weatherstripping 34, increasingly employed in newer vehicle models. Further, the inverted V-shaped portion 32 also provides for enhanced frictional engagement within the window slot opening 30. Referring still to FIGS. 3 and 3A, the generally curvilinearly resilient support portion 24 extends outwardly from the base 36 of the inverted V-shaped portion 32, thence curvingly turning in a downwardly-inwardly biased direction terminating in spring-urged contact with the door interior panel 38. Said spring-urged contact, being in opposition to the said wedgingly-engaged insert portion 22, provides for clamping engagement of the carrier 20 to the thinner and thicker interior door portions 28, 56. As can be seen in FIGS. 1 and 2, the support portion 24 includes slots 40 aligned in longitudinal columns 42 and in horizontally aligned rows 44, providing interconnection means for selectively releasably adjustable engagement with cooperative connecting means in the form of tab ends 46 of the holder 26. The holder 26 consists of a pair of generally horizontally-disposed resiliently curvilinear arm members 48 having out-turned tab ends 46 providing said cooperative connecting means, a downwardly depending spine member 50 and an L-shaped base member 52 with a downwardly hooked tab end 54 providing a further cooperating connecting means for added carrier 20 stability. As can be seen in FIGS. 1 and 2, the resilient arm members 48 may be pinched inwardly to selectively dimension the holder diameter, so that the tab ends 46 may be inserted into the appropriately cooperative slots 40 in outwardly spring-urged engagement with said slots 40 thus securing the holder 26 to the support portion 24. The tab end 54 of the base member 52 is also hook-engaged to the appropriate slot 40. It should be recognized that the resilient arm members 48 may be alternatively fabricated narrowly so as in use to be resiliently urgeable outwardly, instead of pinched inwardly, whereby the tab ends 46 would be inwardly-turned and said spring-urging would be inwardly biased effecting a clamping engagement with the slots 40. It should thus be seen in FIGS. 1 and 2 that the embodiment provides for removably selective diameter adjustability and, as seen in FIGS. 3 and 3A, selectively removably adjustable vertical positioning of the holder 26. It should also be noted that the selectively vertical positioning adjustability function is not dependent on whether the embodiment is clamping or non-clamping in attachment to the interior door portion 28, 56, the invention encompassing either attachment means. The number, size, shape and location of the slots 40 may vary and, as will be seen in another embodiment, variations in the interconnective means may also be employed instead of slots 40 and slot-cooperative tab ends 46 and hooks 54. FIGS. 3 and 3A demonstrate the carrier 20 in functioning positions in clamping attachment to the interior door portions 28, 56 wherein the carrier 20 resiliently accommodates interior door portions 28, 56 of two different thicknesses. As can be observed in the instance of the narrower interior portion 28, slots 40 on one tier or row are engaged, whereas a lower tier or row of slots 40 are engaged on the thicker interior door portion 56, in both instances, positioning the holder 26 in an upright position. Further, one or more top rows 44 of slots 40 provide an ancillary use in allowing unobstructed air passage through louvers forwardly located on doors of many newer vehicles, where a carrier is advantageously mounted, as will hereinafter be explained. In a modified embodiment shown in FIG. 4 wherein like numerals of the previous embodiment have been used for representing corresponding parts with the suffix "a", a carrier 20a includes an insert portion 22a, a support portion 24a and a holder 26a, which carrier 20a functions similarly as and may be of the same materials of the previous embodiment, except for the type of interconnection-engagement means employed between the support portion 24a and the holder 26a and in that this embodiment need not necessarily be clampingly engageable with an interior door portion 28 (shown in FIG. 3) and in certain other aspects may be particular to the instant embodiment as will be explained. The interconnection-engagement means between the holder 26a and the support means 24a includes bulbous male pins 46a and female perforations 40a providing snap-interfitting means well known in the art for horizontal and vertical positioning functioning similarly as the slots 40 and the connecting tabs 46 and hook 54 of the previous embodiment. The holder 26a is a generally cylindrically walled recess 60, which is sectioned along a longitudinal plane into two sections 58 resiliently hinged on the wall 62 of the recess 60. Reference to the embodiment of FIG. 6, which is similar in this sectionally hinged aspect, shows how the sections 58 of the instant embodiment are similarly transversely displaceable providing for selective diameter adjustability of the holder 26a. The support portion 24a and insert portion 22a in part coextensively form a crimped portion 64 allowing the support portion 24a to function as necessary as an insert means. The thickness of the interior door portion 28 to be accommodated will determine to what depth the crimped portion 64 will be inserted into the window slot opening 30 (shown in FIG. 3). At this point it should be observed, better to explain aspects of this embodiment and, incidentally, the embodiment of FIG. 5, that a preferred mounting location of a carrier generally is on the forward portion of a front door interior, where vent windows heretofore were prevalent and are now increasingly less so, and where a user's arm or shoulder will not accidentally dislodge the carrier. However, in this forward location, typically, there is no window mechanism, nor, as such windows are not squared, is there sufficient window surface present for frictional engagement when the window is partially or fully retracted. In such circumstances, it redounds almost entirely to the weatherstripping for engagement of a carrier. Accordingly, the instant embodiment advantageously frictionally engages the weatherstripping 34 at the forward portion of the window slot opening 30 selectively employing, deeply or shallowly, the crimped portion 64 as the insert means for accommodating doors of ranging interior thicknesses. Another variant form of the invention is shown in FIGS. 5 and 6, wherein like numerals have been used to represent similar elements of the previous embodiments with the addition of the suffix "b". The insert portion 22b, the support portion 24b, the recess wall 62b and the base 52b of this embodiment are sectioned along a longitudinal plane forming two longitudinally associated sections 58b hinged on the recess wall 62b as described in the previous embodiment allowing transverse displacement of the sections 58b including in this embodiment the insert portions 22b, the support portions 24b, the recess wall 62b and the base 52b. Accordingly, the insert portions 22b can be flexibly, adjustably and selectively positioned in wedged frictional engagement within the window slot opening 30 to effect a desired diameter setting and vertical disposition of the holder 26b. Particularly visualized, though not meant to be a restriction for this embodiment, is a paper-thin disposable or quasi-disposable plastic carrier 20b possibly suitable for sales-incentive purposes. It should be seen that the carrier 20b may be fabricated having a longitudinally perforated seam (not shown) allowing the carrier 20b to be separated along the seam into two sections to function as hereinbefore described. FIG. 6 also illustrates the carrier 20b as it would function after separation of the perforation. In another modified embodiment shown in FIG. 7, wherein like numerals of the previous embodiments have been used for representing corresponding parts with the addition of the suffix "c", a resiliently deformable insert portion 22c and a resiliently deformable corrugated support portion 24c are fabricated of sheet metal for allowing radical deformation of the support portion for conformation to particular interior door portions 28 of different thicknesses, the corrugation providing for transverse rigidity, longitudinal displaceability and general shape restorability of the support portion 24c. It should be observed that the resiliently deformable metal allows clamping or non-clamping releasable securement to a vehicle door 29. In other aspects, the instant embodiment is similar to the embodiments previously described. Still another modified embodiment is shown in FIG. 8, wherein like numerals have been used to represent similar elements of the previous embodiments with the addition of the suffix "d". The embodiment is similar in function and construction with previously described embodiments except that a coin-tray-article holder 66 has been substituted for a beverage container holder 26 and the slots 40d are disposed in one longitudinal column 42d and the connecting means of the holder 66 is in the form of a single downwardly hooked portion 54d. The insert portion 22d has a partially crimped portion 64d for frictional intervention into a window slot opening 30 functioning similarly as in previous embodiments. It should be observed that means other than the aforementioned crimping means may be employed alternatively, such as fluting, ribbing, pebbling or other non-smooth surface means for enhancing frictional engagement within a window slot opening. It should thus be seen that the beverage carrier of this invention provides an improved and efficient device for detachable securement to a vehicle door and that it is well adapted to meet the conditions of practical use. Since various possible embodiments may be made of the present invention and further changes may be made in exemplary embodiments set forth herein, it is to be understood that all materials set forth and shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.	A carrier for adjustably encircling and simultaneously positioning, a beverage container or article on a vehicle door, includes an insert portion and a support portion, both preferably resilient, and a receptacle. The insert portion, functioning in conjunction with the support portion, provides for removable, adjustable, and preferably clampable carrier mountability on vehicle doors of different interior thicknesses. The support portion is preferably equipped with horizontally and longitudinally aligned slots and the receptacle is equipped with a pair of resilient, container-encircling arms and a base member, all having hooked tab ends for cooperative releasable, adjustable spring-urged interconnection with the slots. Selection of particular slots for interconnection allows the carrier to accommodate beverage containers or articles of different diameters in close confinement and upright position. In a varient embodiment, a coin-tray-article container is substituted for a beverage container receptacle.	8
This application is a continuation of application Ser. No. 149,980, filed May 15 1980. BACKGROUND OF THE INVENTION This invention relates to a tunnel drive shield, in particular to a knife shield having a rear extension. The conventional tunnel drive shield has a knife shield provided with a rear extension. The knife shield has a plurality of elongate members (or knives) arranged side-by-side on a common support frame. The knives can be advanced relative to the support frame, and define a generally cylindrical shield. The rear extension comprises tail extensions of the knives, the tail extensions being supported by a shield tail hood. The shield tail hood is generally part-cylindrical, and open towards the floor of the tunnel, so that a roof support mounted on the floor can be fitted in a temporary or final position. Thus, the known tunnel drive shield permits the possibility of introducing roof support members into the shield tail hood. The roof support members may be, for example, tubbing rings. The arrangement ensures roof support in the critical region between the hood and the finally positioned roof support, when the shield tail hood is advanced. The use of a shield tail hood is particularly advantageous when providing a sprayed-concrete tunnel lining as described, for example, in U.S. Pat. No. 4,120,165. By using a shield tail hood which is built on to the rear of a knife shield, the total length of the drive shield is considerably increased. Particularly in the case of smaller diameter shields, this results in an extremely unfavourable length/diameter ratio. which hinders the carrying out of vertical and horizontal control movements. SUMMARY OF THE INVENTION The present invention provides a tunnel drive shield having a generally cylindrical front shield, and a generally cylindrical rear shield, wherein the rear shield is connected to the front shield in such a manner as to permit the two shields to be angled relatively to one another to a limited extent in all directions. Advantageously, the front shield is provided with a cutting edge at its front end. Preferably, the front shield has a plurality of elongate members arranged side-by-side parallel to the central longitudinal axis of the front shield, said elongate members being supported on, and movable relative to, a support frame, and said elongate members together forming a generally cylindrical shell. In this case, the rear shield may have a plurality of elongate members arranged side-by-side parallel to the central longitudinal axis of the rear shield, said elongate members being supported by a hood and together forming a generally cylindrical shell, and wherein the two shields are connected together by a connection between the support frame and the hood. With this type of drive shield, it is possible to angle the front shield relative to the rear shield to a limited extent, and in all directions. This relative angling of the front and rear shields reduces the rigid length of the drive shield, and so considerably increases the ability of the shield as a whole to negotiate curves. Conveniently, the elongate members of the front shield are relatively thick, profiled knives, and the elongate members of the rear shield are thin-walled, unprofiled metal sheets. Preferably, the connection between the hood and the support frame includes means for holding the rear shield at a given angle relative to the front shield. Said holding means may comprise a plurality of hydraulic operating rams which are fitted between the support frame and the hood, each of said hydraulic operating rams being pivotably attached to both the support frame and the hood. Said holding means can be used for the active adjustment of the angular position between the front shield and the rear shield and/or for immobilising these parts in a given angular position. Advantageously, said hydraulic rams are equispaced about the circumference of the drive shield. Where each elongate member of the front shield is provided with a hydraulic advance ram, the hydraulic advance rams being attached to their elongate members and to the support frame, the working stroke of the hydraulic operating rams may be less than that of the hydraulic advance rams. However, instead of hydraulic operating rams, use can also be made of other holding means, for example springs which urge the shield tail hood into a central position. Advantageously, the connection between the hood and the support frame is a part-spherical bearing whose centre lies approximately on the central longitudinal axis of the drive shield. Preferably, the part-spherical bearing has a support member attached to the support frame, and bearing means attached to the hood, the support member and the bearing means having mutually-engaging, part-spherical bearing surfaces. In this case, the bearing means may comprise a plurality of equispaced bearing segments. The support member expediently forms a rearward extension of the support frame. When operating rams are used, these can be connected, by way of ball-and-socket joints, both to the support frame and the hood. Preferably, rigid backing members are provided for supporting the thin-walled elongate members of the rear shield in the region between the support frame and the hood. Advantageously, rotation-preventing means are provided for preventing relative rotation between the support frame and the hood about the central longitudinal axis of the shield. Preferably, a plurality of rotation-preventing devices comprise said rotation-preventing means, each of said devices comprising a pair of tubular telescoped members, one member of each pair being attached to the support frame, the other member of each pair being attached to the hood. In another embodiment, the hood comprises a plurality of hood segments which are movable relatively to one another, and each of which is advantageously connected to the support frame by means of a respective joint, the joints comprising said connection between the support frame and the hood. In this arrangement, a respective hydraulic operating ram may be associated with each hood segment. Preferably, each hood segment is provided with an integrally-formed, inwardly-extending radial lever arm, the hydraulic operating rams engaging the lever arms. In this case, the hydraulic operating rams may be connected to their lever arms so as to permit limited articulation therebetween. Conveniently, each hood segment is associated with a respective pair of said elongate members of the rear shield. Advantageously, the rear shield is open towards the floor of the tunnel. The elongate members of the front shield may be relatively thick, profiled knives, and the elongate members of the rear shield may be thin-walled unprofiled sheets which are sufficiently resilient to participate in the angular movements between the two shields. As the hood is so supported that it can execute limited movement in all directions, the elongate members of the rear shield are held on the nominal axis of the tunnel in dependence upon the setting of the operating rams, whereas the front shield (which does the actual cutting of the tunnel profile) can be made shorter, and readily participate in the control movement that is initiated. During this phase, the thin-walled elongate members of the rear shield readily adapt themselves to the control movements. The control of the elongate members of the front (knife) shield can be carried out, in the known manner, by pressurising the hydraulic advance rams which are backed by the support frame. By retracting and extending the hydraulic operating rams to varying degrees, the hood can be pivoted in any direction relative to the support frame, and can be immobilised in each position by hydraulically locking the operating rams. BRIEF DESCRIPTION OF THE DRAWINGS Two forms of tunnel drive shield, each constructed in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a part-sectional side elevation of the first form of shield; FIG. 2 is a view of part of the shield of FIG. 1 looking in the direction of the arrow II of FIG. 1; FIG. 3 is a part-sectional side elevation of part of the second form of shield; FIG. 4 is a view looking in the direction of the arrow IV of FIG. 3; and FIG. 5 is a cross-section taken on the line V--V of FIG. 3. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, FIG. 1 shows a tunnel drive shield having a rigid support frame 10 (only the rear portion of which can be seen in FIG. 1) which supports a plurality of elongate members (or knives) 11. The knives 11 are arranged side-by-side parallel to the axis of the tunnel, and form a generally cylindrical shell. The knives 11 are supported and guided on the frame 10, and have cutting edges at their forward ends to attack and penetrate the working face when thrust forwards (in the direction of the arrow V) by a double-acting hydraulic rams 12. Each ram 12 may serve to advance a single knife 11, as illustrated, or a group of knives. Each ram 12 has its cylinder pivotally attached to the frame 10, and its piston rod pivotally attached to the associated knife 11. Extension of any one ram 12 will advance the associated knife 11 in the direction of the arrow V. During the driving of the tunnel, the rams 12 are extended one after another, the frame 10 and the stationary knives 11 (which are in frictional contact with the tunnel wall) collectively acting as an abutment for the ram being extended. When all the rams 12 have been extended in this way, all the knives 11 (and hence the entire cylindrical shell) are fully advanced. Thereafter, the rams 12 are retracted in unison to draw up the frame 10, the frictional contact between the knives 11 and the tunnel wall acting as an abutment for the advance of the frame. This type of tunnel drive shield is known as a knife shield. The actual cutting of the tunnel is accomplished by means of a cutting machine (not shown) which operates within the shield. In known manner, each of the knives 11 is provided with a tail extension 13 constituted by a thin-walled, unprofiled metal sheet having a wall-thickness of between 3 and 5 millimeters. Thus, the tail extensions 13 have a thickness which is considerably less than that of the profiled knives 11. The tail extensions 13 are supported by a common shield tail hood 14, which is constituted by a part-cylindrical sheet-metal jacket which is open towards the floor of the tunnel. A plurality of bearing segments 15 are secured to the inner wall of the hood 14, the bearing segments lying on a common pitch circle. Each bearing segment 15 has a part-spherical bearing face 16, the bearing faces all lying on a sphere whose centre lies on the central longitudinal axis of the shield. The bearing segments 15 are supported on a part-spherical bearing surface 17 of a support member 18. The support member 18 is secured to, and extends rearwardly of, the support frame 10. Thus, the support member 18 extends into cylindrical shell formed by the tail extensions 13. The centre of the sphere which contains the part-spherical bearing surface 17 also lies on the central longitudinal axis of the shield. Consequently, the shield tail hood 14 is supported on the support member 18 for limited pivotal movement in all directions. This enables the support frame 10 and the shield tail hood 14 to be angled relatively to one another. A plurality of double-acting hydraulic rams 19 are positioned between the support frame 10 and the shield tail hood 14, each ram 19 being pivotally connected, by respective ball-and-socket joints 20 and 21, to the frame 10 and the hood 14. The rams 19 are equispaced around the support member 18, and lie roughly on the pitch circle of the rams 12. The working stroke of the rams 19 is considerably less than that of the rams 12. The rams 19 are used to angle the shield tail hood 14 relative to the support frame 10. The rams 19 can also be used to lock the hood 14 at any desired angle relative to the support frame 10, this being accomplished by hydraulically locking the rams 19. Rigid backing members 22 are secured to, and extend rearwardly from, the support frame 10. The backing members 22 reinforce the thin-walled tail extensions 13 in the zone between the end wall 23 of the shield tail hood 14 and the rear end of the support frame 10. The rams 19 are positioned in the space between the backing members 22 and the shield tail hood 14. Each ram 19 is surrounded by a respective guide tube 24, the guide tubes being attached to, and extending rearwardly from, the support frame 10. Each guide tube 24 forms a guide for a respective tubular backing member 25, the tubular backing members surrounding the rams 19, and being secured to the end wall 23 of the shield tail hood 14. Each of the tubular backing members 25 is provided with part-spherical bearing surfaces 26 which engage the inner cylindrical wall of the associated guide tube 24. The tubular members 24 and 25 thus have adequate radial clearance, and so prevent relative rotation between the hood 14 and the support frame 10 about the axis of the shield. Nevertheless, the relative angling of the support frame 10 and the hood 14 is not impeded. The rams 19 could be replaced by other setting devices, for example springs which bias the hood 14 towards its central position. Because of their inherent resilience, the thin-walled tail extensions 13 readily participate in the relative angular movements between the hood 14 and the support frame 10. The bearing segments 15 are welded to the hood 14 by means of sheet-metal webs 27. The backing members 22 are so formed that they extend axially, in a similar manner to the teeth of a "cylindrical comb", between the vertical webs of the knives 11. Thus, even when the knives 11 are advanced, the thin-walled tail extensions 13 are adequately supported in the zone between the hood 14 and the support frame 10, by the backing members 22, and do not deflect under the weight of the surrounding earth. FIGS. 3 to 5 show a modified form of construction, in which the thin-walled tail extensions 13 are supported by a multi-part shield tail hood, which is constituted by a plurality of hood segments 30. The hood segments 30 define a part-cylindrical jacket which is open towards the floor of the tunnel. Each hood segment 30 has an integrally-formed, inwardly-extending, radial lever arm 31. As shown in FIG. 5, the profile knives 11 are guided in T-shaped grooves 37 formed in the support frame 10. Each lever arm 31 is pivotably attached, at a respective pivot joint 34, to a respective bracket 33 attached to the rear end of the support frame 10. Each pivot joint 34 is such as to permit limited movement in all directions, so that the hood segments 30 and the support frame 10 can be angled relative to one another to a limited extent in all directions. The cylinders of the rams 12 which advance the knives 11 are pivotably attached, at 32, to the support frame 10 in the regions of the brackets 33. The rams 19, which angle the hood segments 30, engage the lever arms 31, the cylinder of each ram 19 being mounted in a swivel bearing 35 attached to the associated bracket 33, and the piston rod of that ram 19 being pivotably attached to the associated lever arm 31 by means of a respective link 36. One hood segment 30 has a width equal to that of two tail extensions 13, so that one hood segment provides support for a pair of adjacent tail extensions. Obviously, it would be possible to design the hood segments 30 so as to provide support for one tail extension 13, or for more than two tail extensions. The embodiment of FIGS. 3 to 5 also incorporates rigid backing members 22, these backing members being similar to those of the embodiment of FIGS. 1 and 2. The multi-part formation of the shield tail hood of the embodiment of FIGS. 3 to 5 (and its multi-directional linkage with the support frame 10), increases the ability of this shield construction to negotiate curves. At the same time, the individual hood segments 30 can be thrust towards the tunnel wall, using the rams 19, to prevent undesirable deposits of earth. FIG. 3 also shows roof-support elements 38 within the shield tail hood. These elements 38 form part of either a temporary or a permanent tunnel lining. The apparatus operates in the following manner: if for example it becomes necessary to negotiate a turn to the right from the direction of arrow V in FIG. 1, then the rams 19 on the left side of arrow V will be extended more than those on the right side, with the result that the shield tail hood 14 carrying the knife tail extensions 13 will be angled relative to the frame 10 carrying the knives 11. Not only will the rams 19 impart this angular relationship, but they will also hold the hood 14 relative to the frame 10 until further adjustments are required.	A tunnel drive shield has a front shield and a rear shield. The front shield is a knife shield, and the rear shield has a hood and a plurality of elongate members. The hood is connected to the front shield so as to be movable in all directions. Between the hood and the front shield (or the support frame for the knives of the front shield) is provided means for holding the two shields at a given angular setting. The connection between the two shields enables them to be angled relatively to each other to a limited extent in all directions, so that the original length of the entire drive shield is shortened, and the ability of the shield to negotiate curves is increased.	4
CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application is a divisional application of Ser. No. 10/691,265 filed Oct. 22, 2003. FIELD OF THE INVENTION [0002] The present invention relates to a business form and/or business form with separable label and magnet combination which is printable though the use of a laser or other non-impact printer. The substrate of the present invention is intended to be provided with advertising indicia, marketing messages, remembrance details and the like, but may include other printing or indicia depending on the requirements of the end user. The form construction of the present invention includes a magnetic layer created through the use of a magnetic coating that is applied to the substrate and which may be then be optionally divided or sectioned to create additional separable magnetic elements which may denote separate offers, advertisers, promotions, pictures, etc. that may be adhered to ferromagnetic surfaces. The construction is unique and designed such that it may be processed through traditional down line equipment as well as, offline folding equipment. In addition, the business form of the present invention may also be folded to produce an outgoing mailer construction suitable for processing through the United States Postal Service. BACKGROUND OF THE INVENTION [0003] Magnetic materials have become increasingly common in the business forms and labels industry. Today's growth of new technology plays a vital role in creating and providing businesses with laser compatible forms, which can be sued in a variety of businesses and industries. This present invention has a desired laser compatible substrate and a magnetic layer affixed thereto, that may be used for advertising and marketing, coupon redemption, message memos, emergency numbers, business and service references, photographs, rebates, etc. [0004] Magnets have been previously attached to materials and used for purposes of marketing and advertising. Some exemplary prior uses of magnets include calendars, business cards, frames for photographs, advertising collateral and the like. One example of such a prior art construction is provided in U.S. Pat. No. 5,458,282. The construction includes a solid magnet that is attached to one end of a substrate and, placed between end edges of the substrate and before the separation line of the adjoining substrate section. The difficulty associated with such prior art constructions is that this construction is often limited in usage to the one advertising arrangement provided with the assembly. That is, the magnet may contain a single business card or reference or contact number and the adjoining substrate may only include printed indicia related to that one event. [0005] Such single purpose forms aren't generally economical for use by small businesses or groups of business as minimum quantities of such products may require the purchase of several hundred or even several thousand, whereas a small business may only need a few dozen for selected customers, and then for those products to be potentially personalized. [0006] In addition, to the foregoing drawback, such a construction also requires a magnetic piece to be physically affixed to a substrate in order to use the product for its intended purpose, that of enabling the substrate to be applied to a metallic surface. Due to the increased thickness of the magnetic material, the substrate with the magnet attached cannot easily pass through a laser or other non-impact printer due to the hump or bump created by the magnet. This hump can distort the printing of the substrate and potentially cause excessive wear and tear to the print head of the printer due to the abrupt contact with the raised area of the magnet. Thus, the substrate must first be printed and then have the magnetic piece attached thereto. As might be expected, this can create alignment problems if the magnetic material is applied to the incorrect area of the substrate. [0007] More importantly however, the foregoing thus eliminates the ability for use of such products by small office/home office (“SOHO”) environments, as such environments would not have the desire to purchase rolls of magnetic material, cut the material to size and then affix the material to the substrate being printed. In addition, this prior art construction then virtually eliminates the ability to individually personalize such magnetic pieces, regardless of the size of the business. [0008] What is needed therefore is an advertising piece that may be produced with variable information in one of a number of preconfigured formats and which does not suffer from the drawbacks enumerated above. In addition, there is a need for a magnetic promotional piece having an integral magnetic portion formed therewith that can be produced on an economical and efficient scale. BRIEF SUMMARY OF THE INVENTION [0009] The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention. [0010] This present invention relates generally to a substrate having a non-impact printer (e.g. laser, ink jet) compatible magnetic layer disposed thereon through use of a coatable magnetic slurry. The present invention further includes the ability to provide a multiple segmented magnetic piece that may lend itself to several applications that has various industrial and business uses, including but not limited discrete warnings or messages, marketing and advertising articles, business and service references, coupons, greeting messages, promotional pieces, participation and attendance souvenirs, important address, phone, and fax number displays such as emergency, medical, etc. as well as personal application such as family photographs, images or personal messages. [0011] The present invention overcomes prior art constructions relating to the “bump” created by the additional supplemental magnetic piece through the use of a magnetic layer that may be applied to a substrate in a single pass operation, while enabling the magnetic coated substrate to be utilized in non-impact printers for subsequent personalization. [0012] In other embodiments of the present invention the construction may contain multiple sections, portions or pieces of non-magnetic substrate that can be used and implemented in a variety of ways to accomplish any number of operations or tasks the end-user may have. In addition, the magnetic coated portion of the substrate may also be partitioned, sectioned, etc. so that cooperating or matching magnetic components may be provided with related components or segments on the appended, printed or imaged substrate. [0013] The present invention can be used in a variety of applications in such areas including, but not limited to, retail, marketing, wholesale, advertising, medical & emergency environments and the like. [0014] The magnetic layer of the present invention may be placed at any pre-determined portion or zone of the substrate thus further lending itself to providing a highly variable construction for the end user or recipient. That is, the magnetic layer and/or layers can be placed in a variety of arrangements with predetermined shapes and sizes of both magnetic and non-magnetic substrate. As the magnetic material is applied in the form of a slurry, various patterns can be produced such as geometric shapes and designs as well as characters, animate and inanimate to create an aesthetically appealing presentation piece for not only the manufacturer by also the end user. It should be understood that the magnetic layer and non-magnetic substrate can be provided in a variety of lengths, widths, shapes, sizea, forms, designs, etc. [0015] In a further explained embodiment of the present invention the non-impact printer compatible magnetic piece is described and includes a substrate that has first and second faces having longitudinally extending sides and transversely extending end edges. One of the first and second faces has a first area that can receive indicia and the other of the faces has a second area capable of being coated with a magnetic slurry. The magnetic slurry and substrate creates a substantially planar arrangement that is generally flat and which can be processed through a non-impact printer, such as an ink jet or laser printer. [0016] In one exemplary embodiment of the present invention, a business form with a magnetic portion is described and includes an elongated substrate having first and second faces and first and second longitudinally extending sides and first and second transversely extending end edges. The substrate is divided into at least first and second sections. A magnetic slurry is also provided in the presently described embodiment and is coated on at least one of the first and second sections on at least one of the first and second faces. The magnetic slurry and one of the first and second sections form a magnetic portion that may be applied to a metal or other surface capable of receiving magnetic material. The magnetic portion with the substrate provides a substantially planar configuration that can be processed through a non-impact printer. [0017] In a yet still further embodiment of the present invention, a magnetic advertising assembly is provided and includes a substrate that has first and second surfaces and at least a first line of weakness that divides the substrate into first and second sections. Each of the first and second sections is provided with indicia representative of a promotional offer, personal message, business communication and combinations thereof. One of the first and second sections has at least one line of weakness that divides the section into first and second message portions, with each of the message portions containing a distinct message or offer. [0018] The presently described embodiment also includes a magnetic slurry that is coated on at least one of the first and second surfaces so as to create a substantially planar advertising assembly that can be processed through a non-impact printer. The magnetic slurry with one of the first and second sections of the substrate forms a magnetic portion of the assembly. [0019] Still continuing with the presently described embodiment of the present invention, the magnetic portion has at least one line of weakness that divides the magnetic portion into first and second sections, with each of the first and second sections having a distinct message or offer provided thereon. One of the first and second magnetic sections with its distinct offer thereon corresponds to the distinct message on one of the first and second message portions and the distinct message or offer on another of the first and second magnetic sections corresponds with another of the first and second message portions. [0020] In a yet still further embodiment of the present invention, a mailer assembly having a magnetic portion, is described and includes a substrate having at least first, second and third panels, with one of the panels having a magnetic slurry applied thereto to create a magnetic portion. The substrate further has first and second surfaces, with one of the first and second surfaces forming an exterior of an outgoing mail piece and another of the first and second surfaces forming an internal portion of the mail piece. Each of the first and second surfaces has indicia applied thereto. The magnetic portion cooperating with the substrate to create a substantially planar surface that may be processed through a non-impact printer. When creating the outgoing mail piece, the magnetic portion is folded over onto the second panel and a remaining panel of the first, second and third panels is then folded or wrapped about the magnetic portion so as to enclose the magnetic portion in the outgoing mail piece. [0021] In a yet still further embodiment of the present invention a ferromagnetic slurry for use in creating indicia for a communication document is described and includes a ferrite power provided in an amount ranging from about 50 to about 90% by weight of the slurry and more preferably from about 50 to about 70% by weight; a stabilizer provided in an amount ranging from about 5 to about 20% by weight of the slurry; a varnish provided in an amount ranging from about 15 to about 30% by weight of the slurry and the slurry is curable. BRIEF DESCRIPTION OF THE DRAWINGS [0022] These, as well as, other objects and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the presently preferred exemplary embodiments of the invention in conjunction with the accompanying drawings, of which: [0023] FIG. 1 depicts a front view of the present invention and provides for the areas of the magnetic coating and non-magnetic portions of the assembly; [0024] FIG. 2 illustrates a further view of the present invention and includes a number of separable sections as well as the magnetic portion; [0025] FIG. 3 shows a further embodiment of the present invention and includes a sectionalized magnetic portion provided with unique indicia in each panel and a non-magnetic sectionalized portion with sectional indicia matching that which is provided in connection with the magnetic portion; [0026] FIG. 4 provides a side view of the present invention and further illustrates the various layers used in the construction of the assembly; [0027] FIG. 5 depicts the present invention configured as an outgoing mailer; and [0028] FIG. 5A illustrates a side view of the present invention showing the panels of the assembly in a folded mailer configuration format. DETAILED DESCRIPTION OF THE INVENTION [0029] The present invention is now illustrated in greater detail by way of the following detailed description, but it should be understood that the present invention is not to be construed as being limited thereto. [0030] The term magnetic or ferromagnetic slurry as used herein, refers to a slurry that is applied in-line during printing operations and undergoes several processing steps prior to reaching its final destination. [0031] Application of the magnetic slurry of the present invention may be accomplished by any suitable means such as flexographic, electrostatic, gravure, ion or electronic charge deposition, electro-coagulation printing and the like. Generally, however, printing of the present invention of an exemplary embodiment is done by applying a charge to an imaging drum which then removes an amount of material from a reservoir and applies a corresponding image to a substrate passing beneath the drum. [0032] In one exemplary embodiment of the present invention, the slurry is curable by ultraviolet energy (UV curable) and includes as an exemplary formulation 410 Ferrite Powder, 30 LI Varnish, and a stabilizer additive which gives the invention its unique capability of being able to bind and adhere to substrates during a printing operation. [0033] In one embodiment of the present invention, and exemplary formula includes the following components. Approximately 50-70% of 410 Ferrite Powder by weight of the slurry with about 60-65% by weight being preferred, and about 61-63% by weight being more preferred. Roughly 5-20% of a stabilizer, such as corn starch, by weight of the slurry with approximately 10-15% being preferred and 11-13% being more preferred. Approximately 15-30% by weight of the slurry of 30 LI Varnish with about 20-27% by weight of the slurry being preferred and about 23-26% by weight being more preferred. The 410 Ferrite powder is available from Hoosier Magnetics, Inc., Holland, Ohio; the 30 LI Varnish is available from North West Coatings, Oak Creek, Wis. and the stabilizer, corn starch is available from any retail outlet, such as grocery stores. [0034] The slurry of the present invention is formulated so that the slurry once coated, applied, printed or imaged on the product is UV curable. Application of the slurry to a substrate, after curing results in a layer of cured ferromagnetic material having a thickness ranging from about 0.5 mil to about 25 mil and more preferably the cured thickness of the ferromagnetic material is in the range of about 1 to about 15 mil thickness and still more preferably in the range of approximately 2 to 12 mil thickness. [0035] UV curing is a technology that regularly evolves and efforts are continually sought out in order to achieve improved curing performance so that the printing operation may proceed at optimum speeds. That is, UV curing typically requires a “dwell time” in which the UV curable substance dries before it can be further processed in any additional equipment. As such, it is preferable to achieve faster curing speeds under a variety of difficult and complex environments so as to minimize if not completely eliminate the need for dwell or drying time. [0036] Exemplary bulbs used in curing the slurry of the present invention are “H” bulbs and Gallium doped bulb suitable for use in the UV curing processes described herein, however, it should be understood that other UV curing may be used in accordance with the present invention and the present invention is not limited hereto. [0037] The “H” bulb is generally known as a mercury vapor bulb and is used typically for top surface curing applications. The Gallium doped bulb is used in connection with a requirement for penetrating deep within the slurry mix. The UV bulbs such as those described above along with reflectors are available from the GEW Company, located in North Royalton, Ohio. The combination of topical and penetration curing result in a combination of curing energies sufficient to carry out the present invention. [0038] The process of applying the magnetic slurry is generally described as follows. The substrate which may either be a supply of cut sheet stock or alternatively, a continuous stock such as provided from a roll of material and is supplied to the coating apparatus. The ferromagnetic material is applied to the substrate through the use of a reservoir or well that has been previously filled with a ferromagnetic material, as described above (ferrite powder, stabilizer and a varnish). An image (geometric shape, animate or inanimate shape or simple block pattern) may be created through use of a cylinder, by means of surface tension, which helps create the image configuration, and picks up the UV curable magnetic or ferromagnetic slurry from reservoir. The magnetic slurry adheres to a roller by a charge, surface tension or other means known in the art. [0039] Next, the roller transfers the magnetic slurry material to a print cylinder which has a magnetic plate affixed to the surface of the print cylinder. The magnetic plate then transfers the magnetic slurry to the desired area of the substrate. [0040] An additional magnetic cylinder may be provided and disposed beneath the substrate and in operative association with the print cylinder. The magnetic cylinder aids in pulling the magnetic slurry to the predetermined position on the substrate. The magnetic cylinder also provides for and maintains a consistent transfer of the UV curable magnetic slurry to the substrate. [0041] Once the magnetic slurry is affixed to the substrate, the substrate with the slurry applied then passes through at least one if not additional UV curing stations which contain UV bulbs for curing purposes. [0042] Turning now to FIG. 1 the present invention is generally represented by reference to 10 . The substrate assembly 10 has first and second longitudinally extending sides 20 and 30 and first and second transversely extending end edges 40 and 50 . Numeral 60 depicts the front face or surface of the present invention. The substrate should be one which is capable of receiving printing on both sides. FIG. 1 however, shows printing in optional pre-determined areas, 80 , 90 , 100 and 110 . Numeral 120 depicts an exemplary predetermined location wherein the magnetic layer or slurry is placed on the substrate as described above. [0043] Reference is now directed to FIG. 2 of the present invention, and an exemplary embodiment of the product produced in accordance therewith is depicted generally by reference to numeral 200 . Of course, any substrate can be used, such as 20 pound bond up to 100 pound tag available from Clayton Papers, Independence, Mo. The assembly 200 has a first area 215 and a second area 225 which is provided with a plurality of perforations 220 extending longitudinal side to longitudinal side. The lines of weakness 220 separate the second area 225 into a series of individual message areas that can be provided with individual or distinct messages, one from another. In addition, one line of weakness is used to divide the top section 215 from the bottom section 225 . [0044] The top section in the exemplary embodiment depicted includes the laser compatible magnetic portion, which is contained within the area designated as 210 (substrate with the cured magnetic slurry applied) and the lower section 225 is also laser compatible. Each of the sections is intended to receive indicia. The message sections created by the plurality of lines of weakness 220 , preferably perforations, may be used to accommodate a variety of different sizes of coupons, advertisements, messages, and the like. The lines of perforations 220 also may be placed in any given arrangement in order to accommodate the end users applications and/or requirements. [0045] Turning now to FIG. 3 . Numeral 300 depicts another exemplary embodiment of the present invention. The first face or surface of the substrate is depicted generally by reference to numeral 305 and 308 appears as the second face on the obverse side (not shown). Numerals 310 , 320 , 330 , and 340 are provided and show individual magnetic sections to which distinct indicia or messages have been applied. Reference numerals 350 , 360 , 370 , and 380 provide for distinct message areas on the second portion of the substrate 395 . [0046] In this embodiment, the magnetic portion 390 is separated by lines of weakness that include a first line of weakness and a second line of weakness running substantially perpendicular to the first line of weakness thus dividing the magnetic portion 390 into four substantially quadrate sections. As is shown by the FIG. 2 , the sections are unequal, but it should be understood that the sections can be of equal size or of any size depending on the user. For example, if the advertising assembly were to be distributed by a series of small business owners (4), each of the sizes of the sections would be proportionate to the contribution made to the purchase of the assembly. Those business owners purchasing or contributing more to the purchase would receive a larger block, whereas those contributing less would receive a smaller block of the magnetic portion 390 , such as is illustrated by reference to the blocks, 310 , 320 , 330 and 340 . [0047] Section 395 of the assembly 300 is provided with indicia that matches the respective blocks in the magnetic portion 390 . That is block 350 matches with block or indicia 310 , 360 corresponds to indicia 330 , 370 relates to indicia 320 and 380 pertains to indicia or block 340 . In this way, each of the advertisers is also provided with a coupon or message section for use with their advertising. [0048] In an alternate embodiment, the sections in the magnetic portion 390 could be used by a single advertiser such as a fast food delivery service and each section would correspond to a different night of the week for a different special. For instance, Monday night may enable the caller to receive a large pizza at a special price. Tuesday night may entitle the user to receive a free drink with an order of Buffalo wings, etc. In this way, after the coupons or message sections in second area 395 have been used up, the recipient still has the separable magnet sections to remind him or her of the specials being offered in the evening. [0049] FIG. 4 , depicts a side view of the present invention. Numeral 400 refers generally to the assembly of the present invention. Numeral 420 is depicted as the first face of the substrate and numeral 425 is depicted as a second face of the substrate. Numeral 410 is depicted as a substrate that can be placed on top of the first face of the primary substrate, such as a further detachable label or the like but 410 may also give additional support to the magnetic layer, 495 . Reference numerals 440 , 450 , 460 , 470 and 480 are depicted as first, second, third, fourth and fifth lines of weakness in the substrate, wherein these lines of weakness can be perforations, score lines or any other suitable means for accomplishing the purpose of folding or separation of the assembly. The lines of weakness can be placed in any position of the form assembly, in order to accommodate a diverse display of coupons, advertisements, messages, and the like. [0050] Now turning back to numeral 410 and 495 , you'll note that these substrates are applied to the first face and second face of the primary substrate. In order to make this happen, an adhesive, 490 may be used to accomplish the attachment of label or supporting structure 410 to the substrate. Also as shown in FIG. 4 , the magnetic material 495 may be provided with an over coating or varnish 498 which may impart certain glossy or printability characteristics to the magnetic material. The varnish may be a UV curable varnish, such as UV30LI available from Northwest Coatings as indicated above. [0051] FIG. 5 of the present invention shows the substrate folded into a mailer assembly for an outgoing mail piece and is depicted by reference to numeral 500 . The mail piece is provided with relevant postal indicia such as outgoing and return address information 530 and 520 , respectively. [0052] In order to create the mailing assembly, first, second and third panels are generally used and created by the lines of weakness in the substrate. Once the magnetic slurry has been applied, for instance to a first panel, looking at FIG. 4 with the magnetic portion to the left, the magnetic portion is folded over on to the second panel or central portion of the assembly using one or more of the lines of weakness (see FIG. 4 ). Next the remaining panel or the third panel is folded over or folded about the first (magnetic panel) so as to enclosed the magnetic portion as shown in FIG. 5A . The magnetic material is generally enclosed within the mailer, except that the side edges may be visible as provide din FIG. 5A . [0053] FIG. 5A shows the side view of the mailer generally as 540 . The magnetic portion or first panel 560 , with the removable label 570 is folded over on to the second panel 580 . Then the third or remaining panel 550 is folded over the first panel 560 with the magnetic portion (and label portion 570 ) and essentially lays over the second panel 580 creating the outgoing mail piece. [0054] It should be understood that the internal portion of the mail piece or mailer assembly is formed from the first face of the substrate and the outgoing or external portion of the mailer is formed from the second face or back side of the substrate. The mailer assembly can be imaged on one or both sides and may include the imaging embodiments of the previously described arrangements where matching or cooperating messages are provided on the magnetic portion and the printed portion of the substrate. [0055] It will thus be seen according to the present invention that a highly advantageous lay flat piece with a laser compatible magnetic material has been provided. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it will be apparent to those of ordinary skill in the art that the invention is not to be limited to the disclosed embodiment and that many modifications and equivalent arrangements may be made thereof within the scope of the invention. The scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and products. [0056] The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of their invention as it pertains to any apparatus, system, method or article not materially departing from but outside the literal scope of the invention, as set out in the following claims.	The present invention relates to a business form assembly containing a laser compatible magnetic layer. The business form assembly can be used for a variety of different industries such as business, marketing, advertising, retail, wholesale, personal, and the like. Through the use of a magnetic slurry, a magnetic portion can be created on the business form assembly enabling the assembly to be processed through a non-impact printer as well as to be attached to appliances and other metal surfaces to provide a convenient medium for conveying business or personalized messages. The present invention also provides for the creation of a plurality of separable magnetic elements that may match or cooperate with one or more separable printed portions on the substrate to create an individualized or specialized communication piece.	1
[0001] The present invention relates to the use of iontophoresis to deliver ophthalmic compositions (in particular collyriums) preferably containing riboflavin, or other cross-linking agents, designed to imbibe the corneal stroma in the practice of the corneal collagen cross-linking (CXL) for the keratoconus treatment, and also relates to the corresponding ophthalmic compositions adapted to be administrated by iontophoresis in the treatment of keratoconus by corneal collagen cross-linking. [0002] According to the present invention it is possible to improve imbibition and penetration of the ophthalmic solution into the corneal stroma also without having to proceed to the removal of the corneal epithelium in the practice of the treatment of keratoconus, or other ectasic corneal disorders and to dramatically reduce the needed treatment time. [0003] Collagen is a fundamental protein of connective tissue in animals, and it is present in the cornea and sclera of the eye. Several eye disorders are related to defect in collagen structure and include keratoconus, keratectasia, progressive, myopia, and possibly glaucoma. [0004] Keratoconus is a degenerative disease of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve. Keratoconus is a genetic disease consisting in a non-inflammatory progressive dystrophy whose evolution may be variable from subject to subject. [0005] Upon onset of this disease, which affects approximately 50 persons in every 100.000 each years, generally young people between 10 and 20 years of age, there appears an irregular curvature that modifies the refractive power of the cornea, producing distortions of images and a confused close and distant vision. By passing of the time, vision continues regressing irreversibly, with a consequent need for frequent change of spectacles, and for this reason it may at first be mistaken for a myopia associated to astigmatism. After some years the cornea progressively tends to wear out and thin out towards the apex. There then occurs an irregular curvature of the cornea, which loses its spherical shape and assumes the characteristic cone shape (keratoconus). If the disease is neglected, the top can ulcerate with consequent perforation of the cornea; there appear pain, lacrimation and spasm of the eyelids. These changes of the cornea produce an alteration in the disposition of the corneal protein, causing micro-scars that further distort the images and in some cases prevent passage of light, thus giving rise to a troublesome dazzling feeling. [0006] On account of the congenital structural weakness of the corneal stroma due to said disease, after some years the cornea progressively tends to wear out and thin out towards the apex. There then occurs an irregular curvature of the cornea, which loses its spherical shape and assumes the characteristic cone shape (keratoconus). [0007] If the disease is neglected, the top can ulcerate with consequent perforation of the cornea; there appear pain, lacrimation and spasm of the eyelids. These changes of the cornea due to keratoconus produce an alteration in the disposition of the corneal protein, causing micro-scars that further distort the images and in some cases prevent passage of light, thus giving rise to a troublesome dazzling feeling, above all at times of the day when the sun is low on the horizon (sunrise and sunset). [0008] Current treatments for keratoconus either tend to mask the eye surface irregularity with contact lenses, or attempt to improve the surface contour with intracorneal ring segments, lamellar keratoplasty, or excimer laser surgery. However, the disease is progressive and none of these options obviates, the need for eventual corneal transplantation. In fact, when the cornea affected by keratoconus undergoes considerable thinning or if cicatrization occurs following upon lacerations of the corneal surface, surgical transplantation of the cornea (keratoplasty) becomes necessary. [0009] However, in the ophthalmic clinic of the Carl Gustaw Carus University of Dresda in 1997, a new safer and less invasive technique was developed, referred to as “corneal cross-linking” (CXL), which uses in particular riboflavin, activated by a UV laser; from then on this technique has been widely and successfully used in various eye clinics. [0010] Corneal cross-linking is a minimally-invasive method, which uses riboflavin activated by a UV laser (365-370 nm); the method is painless and is carried out in day-hospital. Cross-linking enables reinforcement of the structure of the cornea affected by keratoconus through the interweaving and increase in links (cross-linking) between the fibers of the corneal collagen. [0011] Clinical studies have proved CXL being able to reduce the astigmatism associated to keratoconus as well as to slow down or arrest pathology evolution, thus avoiding the need for transplantation of the cornea. Also other disorders characterized by corneal ecstasia benefit from treatment using the cross-linking method. [0012] Corneal cross-linking is carried out by applying a local corneal anaesthesia for making the abrasion of the corneal epithelium (de-epithelization) having a diameter of 8-9 mm. This is followed by a frequent instillation of a 0.1% riboflavin-based ophthalmic solution, during 15 minutes, followed by irradiation with ultraviolet (UV-A) emitter, during 30 minutes with instillation of riboflavin solution throughout the irradiation operation. [0013] Riboflavin (molecular weight 376, poorly soluble in water), more preferably riboflavin sodium phosphate (molecular weight 456, negatively charged), which is commonly used in corneal cross-linking, is a hydrophilic photosensitizing and photopolymerizing molecule with a poor capacity for diffusing through the epithelium and hence reaching the corneal stroma. [0014] Riboflavin, also known as vitamin B 2 , is required for a wide variety of cellular processes, it is an easily absorbed micronutrient with a key role in maintaining health in humans and other animals. Riboflavin plays a key role in energy metabolism, and for the metabolism of fats, ketone bodies, carbohydrates, and proteins. [0015] Riboflavin has been employed in several clinical and therapeutic situations. For over 30 years, riboflavin supplements have been used as part of the phototherapy treatment of neonatal jaundice; it has also been used as a muscle pain reliever, and alone or along with beta-blockers, in the prevention of migraine. [0016] In the practice of the corneal collagen cross-linking (CXL) for the keratoconus treatment, riboflavin drops are applied to the patient's corneal surface. Once the riboflavin has penetrated through the cornea, ultraviolet A light therapy is applied. The UV-A riboflavin induced cross-linking of corneal collagen is consisting in the photo-polimerization of stroma collagen fibrils aimed to increase their rigidity and resistance. [0017] The technique has been shown and described in several studies to stabilize keratoconus. [0018] The application of a photosensitizer such as riboflavin-5-phosphate to a tissue, e.g. cornea, skin, tendon, cartilagin, or bone, followed by photoactivation is the object of the invention disclosed in the U.S. Pat. No. 7,331,350, which can produce a tissue-tissue seal for instance to repair a wound or seal a tissue transplant. Said described method can be applied to different type of surgical procedures such as corneal transplant surgery, cataract surgery, laser surgery, keratoplasty, penetrating keratoplasty, refractive surgery, cornea reshaping, and treatment of corneal laceration is providing a cross-linking tissue method creating tissue seal. [0019] A method for performing oculoplasty for the treatment of corneal dystrophies/keratoconics including applying a riboflavin solution as photosensitizer to a human eye surface and irradiating the treatment region with controlled photoactivating radiation is described in patent application US 2008/0015660. [0020] An ocular solution containing approximatively 0.05-0.25% w/w of riboflavin phosphate and approximatively 20% w/w of dextran for the use in the technique of corneal cross-linking for the treatment of keratoconus is the object of the international patent application WO 2009/001396. The innovative contribution of the dextran to this solution is guaranteeing a good muco-adhesiveness to the ocular surface enabling a better performance of the contact and hence of the impregnation of the corneal stroma by the riboflavin solution. [0021] A very simple formulation relating to a collyrium for the treatment of patients suffering from conical cornea has been recently disclosed by the European patent application EP 2 0253 321. In such formulation, only containing riboflavin-5-phosphate, sodium chloride, benzal chloride and sterile water, the riboflavin photosensitizing substance and the benzal chloride, acting as surface-active agent, assist the penetration of the collyrium in the corneal epithelium; compared to standard collyria for the treatment of conical cornea, the product obtained by this described composition has the advantage of not requiring the removal of the corneal epithelium. [0022] A similar technical solution is obtained through UV-A irradiation of a riboflavin/collagen mixture in the presence of copious oxygen causing rapid cross-linking resulting in adhesion of the mixture in situ effecting its adhesion to underlying ocular structure. Such corneal and scleral tissue seal is disclosed in the International Patent Application WO 2009/073600 in order to obtain a structural augmentation of ocular tissue for better stabilizing progressive corneal diseases. [0023] As demonstrated by the above cited scientific and patent literature, riboflavin (molecular weight 376, poorly soluble in water), and more preferably riboflavin sodium phosphate (molecular weight 456, negatively charged), is the preferred hydrophilic photosensitizing and photopolymerizing molecule mostly used in performing corneal cross-linking; however, it has a poor capacity for diffusing through the epithelium and hence reaching the corneal stroma. [0024] In order to facilitate the absorption thereof and the complete imbibition of the corneal stroma before starting the irradiation with UV-A, it has been introduced the technique of removing the corneal epithelium (de-epithelization). However, this procedure can create, albeit rarely, complications at a corneal level, pain, in addition to being a method that renders the task of the oculist more difficult. [0025] To overcome said problem, the international patent application PCT/IT2009/000392, and relative priority patent application RM2008A00472, disclose an ophthalmic compositions for corneal cross-linking in the treatment of keratoconus or other corneal ectasic, characterized by the association of riboflavin and specific bio-enhancers in order to try to solve the technical problem of the poor capacity of riboflavin for diffusing through the epithelium and hence reaching the corneal stroma. In fact, by the addition of the disclosed bio-enhancers, the riboflavin based compound facilitates epithelial absorption associated to corneal CXL, avoiding the resort to the removal of the corneal epithelium, enabling a non-invasive corneal elimination or reduction of the anaesthesia and consequent fast healing without pain or possible complication for the patients. [0026] However, despite the important advances in the relevant field of riboflavin solutions, there is still the need of more efficient delivery systems for releasing ophthalmic compositions to imbibe corneal stroma in the practice of corneal cross-linking for the treatment of keratoconus, and of suitable ophthalmic compositions for the treatment of keratoconus specifically formulated to be adapted to the more efficient corneal application as well. [0027] It would hence be desirable to further improve the absorption of riboflavin, to reduce riboflavin administration time, without requiring the removal of the corneal epithelium, hence obtaining a noninvasive corneal cross-linking with elimination or reduction of the anesthesia, which does not need particular post treatment therapy, no edema due to the removal of the epithelium, and consequent fast healing without pain or possible complications for the patient. [0028] Iontophoresis is a noninvasive method which allows the penetration of high concentration of ionized molecules, such as drugs, into living tissue driven by an electric current, in fact, applying a current to an ionizable substance increases its mobility across a biological surface. [0029] Three principle forces govern the flux caused by the current. The primary force is electrochemical repulsion, which propels species of the same charge through tissues. When an electric current passes through an aqueous solution containing electrolytes and a charged material (for example, the active pharmaceutical ingredient), several events occur: [0000] (1) the electrode generates ions, (2) the newly generated ions approach/collide with like charged particles (typically the drug being delivered), and (3) the electrorepulsion between the newly generated ions force the dissolved/suspended charged particles into and/or through the surface adjacent (tissue) to the electrode. [0030] Continuous application of electrical current drives the active pharmaceutical ingredients significantly further into the tissues than is achieved with simple topical administration. [0031] The degree of iontophoresis is proportional to the applied current and the treatment time. It occurs in water-based preparations, where ions can be readily generated by electrodes requiring aqueous media containing electrolytes; so iontophoresis is governed by the extent of water hydrolysis that an applied current can produce. The electrolysis reaction yields either hydroxide, OH− (cathodic) or hydronium H3O+ (anodic) ions. Some formulations contain buffers, which can mitigate pH shifts caused by these ions. However the presence of certain buffers introduces like charged ions that can compete with the drug product for ions generated electrolytically, which can decrease delivery of the drug product (and increase application time). [0032] The electrical polarity of the drug delivery electrode is dependent on the chemical nature of the drug product, specifically its pK a (s)/isoelectric point and the initial dosing solution pH. It is primarily the electrochemical repulsion between the ions generated via electrolysis and the drug product charge that drives the drug product into tissues. Thus, iontophoresis offers a significant advantage over topical drug application, in that it increases drug absorption. The rate of drug delivery may be adjusted by varying the applied current by the person skilled in the art. [0033] Due to the highly effective administration way of the iontophoretic process, ophthalmologist have long recognized the value of iontophoresis in the delivery of curative molecules to the eye and in the treatment of ocular pathologies, as not only the iontophoretic process permits a more rapid medicine application, but it also allows a more localized and more highly concentrated application of drugs. [0034] Several iontophoretic devices have been developed and improved to be specifically used in eye medical field, and following the technical advances occurred in the last decades in the iontoforesis field, in particular concerning devices and apparatus, currently research and development mainly focus on several optimized formulations suitable for delivery by ocular iontophoresis and methods of use thereof. [0035] Described herein are riboflavin based formulations to be employed in an innovative way for performing CLX deliverable by iontophoresis to treat structural weakness of the corneal stroma, in particular keratoconus, and uses thereof. [0036] Riboflavin sodium phosphate, commonly used in corneal cross-linking, is a low molecular weight, water soluble, negatively charged molecule; such set of features makes it potentially a suitable target for cathodic iontophoresis as shown below. [0037] More in detail, in iontophoresis the three transport mechanisms, chemical, electrical and electroosmotic fluxes are explicited in the Nernst-Planck equation below: [0000] Flux total =Flux passive +Flux electric +Flux osmotic [0038] According to Prausnitz M. R. and Noonan J. S., “Permeability of Cornea, Sclera, and Conjunctiva: A Literature Analysis for Drug Delivery to the Eye”. 1998. Journal of Pharmaceutical Sciences. 87:1479-88, for simplicity it can be assumed that the passive contribution is negligible. The electrorepulsion flow depends on charge (valence), electrical field and concentration, which are proportional to current density and inversely proportional to ions mobility in fluid. In turn, ion mobility depends upon several factors such as concentration, interaction between ionic species themselves and between the ions and the solvent molecule, size of the charged drug molecule, polarity of the solvent, . . . etc. The electroosmotic flow occurs when an electrical field is applied across a membrane and produces bulk motion of the solvent itself that carries ionic or neutral species with the solvent stream. It is proportional to concentration of both ionic and neutral species of the drug. [0039] The electroosmotic flow is in the direction of the membrane charge's counter-ions. At physiological pH (7.4), skin, like most of the biological membranes including cornea and sclera is negatively charged. Therefore, the electroosmotic flow enhance anodic (+) delivery of positively charged drug while cathodic (−) of negatively charged drug delivery is retarded. [0040] At low pH, over pI, isoelectric value of the cornea and sclera considered to be 4 (see Huang et al, Biophysical journal 1999) and comparable to skin surface's pI values that ranges from 3 to 4, the surface turns positive and electroosmotic flux reverses. That explains the importance of buffering, which besides the fact it protects conjunctival and corneal damage (eye can tolerate a fairly wide pH range and Ophthalmic solutions may range from pH 4.5-11.5, but the useful range to prevent corneal damage is 6.5 to 8.5), but it keeps the relative contribution of each flow at a constant level. It also guaranties a stable number of ionic species in the solution if the duration of applied current is kept short. DESCRIPTION OF THE INVENTION [0041] Described herein are formulations designed to enhance their delivery into and through the eye, adapted to be administered by iontophoresis and relative method thereof. More specifically, the herein described ophthalmic compositions are based on riboflavin or other cross-linking agent having at the same time buffering properties, to be delivered by iontophoresis. In such a way it is possible to improve imbibition and penetration into the corneal stroma without having to proceed to the removal of the corneal epithelium in the practice of the treatment of keratoconus, or other ectasic corneal disorders, by means of corneal cross-linking. Therefore, according to the present invention the ophthalmic solution to be delivered by iontophoresis, preferably has to have an initial pH value in the range comprised between 5-6 in order to act as buffering agent and reach a final pH value not above 9. [0042] The described method for treating keratoconus focuses on developing riboflavin based formulations and use of said formulations to maximize riboflavin delivery through iontophoresis, and patient safety. The application of the described riboflavin based formulations by iontophoresis is novel and suitable for treating corneal ectasia disorders. [0043] Therefore, it is object of the invention to provide a specific product formulation adapted to corneal imbibition associated to CXL to be transferred to the cornea by iontophoresis and to be subsequently irradiated by UV light. [0044] Another object of the invention is to propose an ocular iontophoresis method using a riboflavin solution in a form that is more easily ionizable. [0045] The formulations, which include riboflavin at different concentrations, can be used in presence of different iontophoresis conditions (e.g. current levels and application times). These formulations can, for example, be appropriately buffered to manage initial and terminal pHs, or include other excipients that modulate osmolality. Furthermore, the riboflavin solutions are prepared in a such a way to minimize the presence of competing ions. [0046] This ocular iontophoretic based approach is a novel, non-invasive, and a much more efficient method which can lead to better results than those achieved by classical riboflavin administration ways to introduce riboflavin to the cornea to be treated by CXL. Remarkably, as the administration time is significantly reduced due to increased transfer efficiency, the procedure results much more comfortable for patients. [0047] According to the present invention riboflavin is used in appropriate amounts chosen between 0.001 wt % and 1 wt % with respect to the composition. [0048] In addition, the riboflavin preferably used in the present invention is riboflavin phosphate in appropriate amounts in all the compositions described above; in particular it is preferably present at between 0.05 wt % and 0.4 wt % of the composition of the present invention. [0049] In the preferred embodiment of the invention it has been proven that the riboflavin phosphate solutions used in the achievement of the present invention shows optimal parameters relatively to pH measurements and conducibility making said solutions particularly idoneous to be administered by iontophoresis; in particular, a riboflavin phosphate solution 0.1 wt % of the present invention has a pH value of 5.62 and conducibility of 186.9 μSiemens/cm at room temperature, a riboflavin phosphate solution 0.2 wt % exhibits pH value of 5.79 and conducibility of 350.0 μSiemens/cm, while the pH value is 5.93 and the conducibility is 673.2 μSiemens/cm when the concentration of riboflavin phosphate in the solution raises to 0.4 wt %. [0000] So, the pH value of the solution, formulated with an excess of Rib-P—Na, a minimum of sodium phosphate buffer (or other buffering systems), and a pH adjusted below physiologic pH (5-6), during a 1 to 5 min iontophoresis process at an intensity of 1 mA, will slowly shift to 8-9, which is tolerated by the eye. This feature allows the addition of small amounts of buffer in the solutions which will minimize the competition with Riboflavin being delivered into the eye. [0050] So, in such embodiment, riboflavin monophosphate monosodium salt (Rib-P—Na) used in the formulation will act as a buffer. Upon application of cathodic current, the following reaction will occur at the cathode (water hydrolysis): 2H 2 0+2e- ->2OH − +H 2 . [0051] Another embodiment of the invention envisages compositions based on riboflavin specifically formulated to be delivered by iontophoresis and containing enhancers such as bio-enhancers and photo-enhancers. [0052] Bio-enhancers are substances that promote the passage of riboflavin or other photosensitizing and photopolymerizing substances through the corneal epithelium, enabling absorption by the corneal stroma itself, such as for example: EDTA associated to tromethamine, ophtalmologically acceptable EDTA salts associated to tromethamine, polysorbate 80, tromethamine, azone, benzalkonium chloride, cetylpyridinium chloride, cetyltrimethylammonium chloride, lauric acid, menthol, methoxysalicylate, polyoxyethylene, sodium glycholate, sodium glycodeoxycholate, sodium lauryl sulphate, sodium salicylate, sodium taurocholate, sodium taurodeoxycholate. [0053] Photo-enhancers are photosensitive and photopolymerizing substances that can be readily absorbed by the epithelium and that, like riboflavin, can also be activated by light to form corneal cross-linking, such as for example the dyes acridine yellow, quinidine yellow, methylene blue, and erythrosine. [0054] In another embodiment of the invention, riboflavin formulated with high molecular weight buffers that will not penetrate cornea and will minimize competition with low molecular weight compound. In this variant, the sodium phosphate monobasic buffer has a relatively low molecular weight compared to riboflavin and will compete during iontophoresis. It could be replaced with higher molecular weight buffers such as HEPES, or PIPES or other ones with similar physical and chemical properties. [0055] The ophthalmic compositions of the present invention can be prepared in the technical form of collyriums and eye-drops, gels, and in any case in all the pharmaceutical technical forms that enable a corneal application followed by iontophoresis according to known techniques; given hereinafter are examples provided by way of illustration, without this implying any limit to the present invention. Other aspects, advantages, and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains. [0056] Formulations are reported below, the dosage of the individual components is expressed in weight percentage. Example 1 [0057] [0000] Ingredients % w/w Riboflavin phosphate 0.146 g Dextran T500 20.00 g NaH 2 PO 4 •2H 2 O 0.225 g Na 2 HPO 4 •2H 2 O 0.950 g NaCl 0.116 g H 2 O Up to 100 g Example 2 [0058] [0000] Ingredients % w/w Riboflavin phosphate dehydrated 0.147 g sodium salt Dextran T500 15 g Sodium EDTA 0.1 g Tromethamine 0.1 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g Example 3 [0059] [0000] Ingredients % w/w Dextran T500 15 g Sodium EDTA 0.2 g Tromethamine 0.2 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g Example 4 [0060] [0000] Ingredients % w/w Riboflavin phosphate dehydrated 0.147 g sodium salt Dextran T500 15 g Quinoline Yellow 0.050 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g Example 5 [0061] [0000] Ingredients % w/w Riboflavin phosphate dehydrated 0.147 g sodium salt Dextran T500 15 g Acridine Yellow 0.050 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g Example 6 [0062] [0000] Ingredients % w/w Riboflavin phosphate dehydrated 0.147 g sodium salt Dextran T500 15 g Erythrosin B 0.050 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g Example 7 [0063] [0000] Ingredients % w/w Riboflavin phosphate dihydrated 0.147 g sodium salt Dextran T500 15 g Methylene blue 0.050 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g Example 8 [0064] [0000] Ingredients % w/w Riboflavin phosphate dehydrated 0.147 g sodium salt Dextran T500 15 g Sodium EDTA 0.1 g Tromethamine 0.05 g Dehydrated monobasic sodium phosphate 0.067 g Dehydrated dibasic sodium phosphate 0.285 g Distilled water Up to 100 g In one embodiment particularly preferred of the present invention, formulations according to examples 1 to 8 provide dehydrated monobasic sodium phosphate and/or dehydrated dibasic sodium phosphate, constituting the buffering system, in variable amounts such to reach the final solution pH value of 5.5, as easily available to the person skilled in the art. It is to be considered also every other buffering systems (such as citrate, acetate, tartaric acid) useful to obtain such a value of pH 5.5-6.	Iontophoresis for delivering ophthalmic compositions (in particular. collyriums) preferably containing riboflavin, or other cross-linking agents, designed to imbibe the corneal stroma in the practice of the corneal collagen cross-linking (CXL) for the keratoconus treatment, and the corresponding ophthalmic compositions adapted to be administrated by iontophoresis in the treatment of keratoconus by corneal collagen cross-linking. Additionally, an ophthalmic composition for the treatment of keratoconus by corneal iontophoresis characterized by the fact that it includes cross-linking agents having buffering properties and whose initial pH value is included between 5 and 6, and/or bio-enhancers, and/or photo-enhancers.	0
BACKGROUND OF THE INVENTION The present invention relates to using CCD (charge coupled device) imagers in a television camera, and more particularly, to using such imagers that have defects. Present CCD imagers suffer from low yields due to imperfections and defects in the integrated circuit chips from which they are fabricated. Various schemes have been used to correct for the signal disturbances that result from such defects. For example U.S. Pat. No. 3,904,818 shows a system that in effect does dropout compensation. The system detects when a photosensor provides excessive dark current, and if so, substitutes a signal that is the average of signals provided by photosensors surrounding the defective one. However, an average of signals from surrounding photosensors may not be a close enough approximation to be satisfactory. Also, other photosensors in the area may be affected by the defect and averaging may not produce an acceptable correction. Other schemes, such as shown in U.S. patent application Ser. No. 242,265, filed Mar. 10, 1981, in the names of W. H. Meise and R. A. Dischert, use two imagers and two ROMs (read only memories) programmed with defect locations of the imagers. Normally the output signal is derived from both imagers for best signal-to-noise ratio. When a defective photosensor is about to be read from one imager, the output signal is derived from just the other imager. However, this scheme may require complex and expensive circuitry, e.g. the ROMs and their associated circuits. Still another scheme is shown in Japanese Patent (Kokai) No. 54-56722. As shown therein a flaw detector, which comprises a threshold circuit, receives the output signal from one of two imagers. When the output signal exceeds the peak white level or goes below black level, thereby indicating a defective photosensor, the threshold circuit provides an output signal to perform a switching function so that the video signal output for the entire circuit is now derived from the second imager. However, this circuit cannot detect grey level defects that result in incorrect video signals between the black and white levels. It is therefore desirable to have a defect compensation circuit that has high resolution, low cost, and detects grey level as well as severe defects. SUMMARY OF THE INVENTION An imaging method and apparatus comprising imaging a scene onto a plurality of imagers, said imagers being subject to defects, obtaining signals from said imagers to allow producing a visible image, comparing signals from said imagers to determine which signals are not representative of the scene due to said defects, and adding said signals together to form an output signal except when a signal from a defect is present and otherwise blocking a signal derived from a defect from forming said output signal. DESCRIPTION OF THE DRAWINGS FIG. 1 shows a circuit diagram of a portion of a video camera, and FIG. 2 shows a logic diagram of a driving circuit for switches present in FIG. 1. DETAILED DESCRIPTION FIG. 1 shows an object 10, which reflects ambient light through an infra-red filter 12, which reduces the infra-red pick-up of the imagers, through a focussing lens 14 into a beam splitter 16. Splitter 16 comprises two contiguous triangular cross-section prisms with a half-silvered mirror disposed therebetween. One-half of the light goes to CCD imager 18, which lies in the focal plane of lens 14, while the other half of the light is reflected from inverting mirror 20 to correct for the inversion of the half-silvered mirror, and then goes to CCD imager 22, which also lies in the focal plane of lens 14. Mirror 20 ensures that the image on imagers 18 and 22 are in the same sense. Mirror 20 can be eliminated if imager 22 is clocked in reverse with respect to imager 18. If desired imagers 18 and 22 can be horizontally offset from one another by one-half a photosensor width for improved resolution and reduced aliasing. The initial photosensor of each line of each of imagers 18 and 22 is covered up. Thus the output signal from these photosensors comprises a black level signal. A black level signal derived in this fashion will change with temperature exactly as the black level from the remaining photosensors on the line since they are on the same substrate. A clock generator (not shown) synchronously causes scanning to take place within imagers 18 and 22 so that both imagers are simultaneously providing a signal from corresponding photosensors. The signals from imagers 18 and 22 are respectively applied to clamp circuits illustrated as blocks 23 and 25, which clamp circuits receive a clamping pulse from a generator (not shown) when the covered photosensors are being read out. A clamping voltage from, e.g. a potentiometer (not shown), is also applied to the clamping circuits 23 and 25. Since the time constant of the clamping circuits is a few horizontal line periods, the dark current for the entire line is held constant at the clamping voltage. The clamped signals, from clamping circuits 23 and 25, is then respectively applied to emitter followers comprising transistors 24 and 26 and resistors 28 and 30. Most of the time there will be good signals from both imagers 18 and 22, and therefore it is desired to add the signals from the two imagers together for improved signal-to-noise ratio. To achieve this, the signals from transistors 24 and 26 are applied to FET (field effect transistor) switches 32 and 34 respectively, which switches are normally in the ON (passes signal) state due to the biasing of their gates. The output signals from switches 32 and 34 are applied to an adder including equal value resistors 36 and 38. Resistors 36 and 38 should have equal value so as to obtain a 3 db signal-to-noise ratio improvement when signals from both imagers are present. Further, resistors 36 and 38 can comprise the ON resistance of FETs 32 and 34. The output of the adder is coupled to an emitter follower including transistor 40 and resistor 42. The video output signal is provided at output terminal 44. When one of the imagers has a defective photosensor, the gate bias on the appropriate FET switch can be changed so that the switch is in the OFF (blocks signal) state. The present invention generates FET switching (gate biasing) pulses by comparing the two signals from the imagers without the use of a defect location memory. It is based upon the nature of defects that have been observed in the imagers: either a defective pixel is brighter than it should be (as seen in white lines or spots in the picture) or it is darker (dark or black lines or spots). The following algorithm will correct defects, assuming that only one of the imagers has a defect at any particular location, which condition can be satisfied by careful selection of the imager pairs. If one imager output signal is higher than the other, the one that is higher is assumed to be a bright defect, and only the other imager output signal is used, unless the lesser output signal is black, in which case it is assumed to be a black defect, and the higher output signal is used. FIG. 2 shows the circuitry for implementing the above algorithm. A black reference signal, which comprises the clamping voltage applied to clamps 23 and 25, is received at input terminal 50. The black reference signal is applied to the non-inverting input of comparators 56 and 58. The video signal from the emitter of transistor 24 (video A) is received at input terminal 52 and applied to the inverting inputs of comparators 56 and 62 and to the non-inverting input of comparator 60. The video signal from the emitter of transistor 26 (video B) is received at input terminal 54 and applied to the non-inverting input of comparator 62 and the inverting inputs of comparators 58 and 60. Comparator 56 provides a ONE output signal when video signal A is less than black level, which output signal is called "A is black", to AND gate 64 and to the inverting input of AND gate 66. Similarly comparator 58 provides a ONE output signal when video signal B is less than black level, which output signal is called "B is black", to the inverting input of gate 64 and to gate 66. The output signal from gate 64 is ONE when only A is black and is applied to the inverting input of AND gate 72 and to AND gate 74. Similarly, the output signal from gate 66 is ONE when only B is black and is applied to the inverting input of AND gate 68 and to AND gate 70. Comparator 60 provides a ONE output signal called "A is greater than B" to gates 68 and 70 when signal A exceeds signal B by a threshold amount. Similarly, comparator 62 provides a ONE output signal called "B is greater than A" to gates 72 and 74 when signal B exceeds signal A by a threshold amount, which threshold is determined by an external bias voltage applied to one of the input signals of each comparator. The threshold levels allow for noise always causing slight differences between signals A and B from imagers 18 and 22. The output signal from gate 70 is ONE if A is greater than B and if only B is black. This means that B is a black error. The output signal is applied to OR gate 76. The output signal from gate 68 is ONE if A is greater than B and if not only B is black, i.e. there are no black errors, or A is black, or both A and B are black. This output signal is called "A is a white error", which includes not only A being actually white, but A is black but greater than B. The output signal from gate 68 is applied to OR gate 78. Similarly, the output signal of gate 74 is ONE if B is greater than A and only A is black. This means that A is a black error. The output signal is applied to gate 78. The output signal from gate 72 is ONE if B is greater than A and if not only A is black, i.e. there are no black errors, or B is black, or both A and B are black. This output signal is called "B is a white error", which includes not only B being actually white, but B is black but greater than A. The output signal from AND gate 72 is applied to OR gate 76. The output signal from OR gate 76, called "B error", is ONE if there is either a black or white error in signal B. Similarly, the output signal from OR gate 78, called "A error", is ONE if there is either a black or white error in signal A. The following truth table describes the operation of FIG. 2. ______________________________________Output Output Output Output Output OutputCase of 60 of 62 of 56 of 58 of 78 of 76______________________________________1 0 0 0 0 0 02 0 0 0 1 0 03 0 0 1 0 0 04 0 0 1 1 0 05 0 1 0 0 0 16 0 1 0 1 (Impossible)7 0 1 1 0 1 08 0 1 1 1 0 19 1 0 0 0 1 010 1 0 0 1 0 111 1 0 1 0 (Impossible)12 1 0 1 1 1 013 1 1 0 0 All Impossible14 1 1 0 1 Input15 1 1 1 0 Combinations16 1 1 1 1 to Gates 76 & 78______________________________________ Certain combinations of input signals A and B cannot arise. These are: Case 6: B is greater than A, and B is black, but A is not black, since A cannot be both bigger and smaller than A. Case 11: A is much greater than B, and A is black, but B is not black. This is just the reverse of case 6. Case 13-16: A is much greater than B, and B is much greater than A. Since FET switches 32 and 34 are N-channel devices, the "A error" and "B error" signals are inverted in inverters 82 and 80 respectively in FIG. 2 before going to the FETS, so that when "A error" is ONE, FET 34 is turned off and when "B error" is ONE, FET 32 is turned off. It will be noted that when no defects are present and both FETs are providing signal, the high input impedance of transistor 40 does not load down resistors 36 and 38. When FET 32 or 34 is open due to a defect, transistor 40 still does not load down resistor 36 or 38 respectively. Thus the output voltage at terminal 44 remains a constant for constant illumination of imagers 18 and 22. The delay in the video paths from the two imagers must be matched to the delay in the comparator/logic circuitry.	A TV camera comprises a pair of CCD imagers subject to defects. Defect detection is done by comparing signals from the imagers, thus saving the expense of a defect location memory and also detecting more kinds of defects than one would detect by just comparing one signal to a fixed reference. As a result, CCD imagers with defects can be used thus increasing production yield of such imagers.	7
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates generally to equipment racks. Specifically, the invention relates to equipment racks that are adjustable and capable of holding sports equipment such as bicycles and skis, and that also mount and secure to vehicles for transportation. [0003] 2. General Background and State of the Art [0004] There are many prior art equipment racks that mount on vehicles for the transportation of sports equipment and other articles. One such equipment rack, disclosed in U.S. Pat. No. 5,495,970, includes several structures removably mounted around a shaft. These structures are removable from the shaft and replaceable to create different angular positions relative to the shaft. However, the angles created by repositioning the structures are limited, and the removability of the structures creates a potentially cumbersome apparatus that hinders quick and easy handling. [0005] Another prior art equipment rack, disclosed in U.S. Pat. No. 5,211,323, includes a pair of mounting members for mounting to a vehicle and supporting arms connected to the mounting members. The mounting members are pivotally connected for rotation between a plurality of adjusted positions. Yet another prior art equipment rack is disclosed in U.S. Pat. No. 5,135,145, which discloses a heavy duty bicycle rack having support legs with limited angular movement. The invention also includes support arms for holding bicycles which are adjustable without having to the adjust the position of the legs. Both of these patents feature racks that have structural components which pivot relative to each other, limiting the positions in which the rack can be placed on a vehicle. Furthermore, there is no centralized frame around which all structural and support components move. INVENTION SUMMARY [0006] The present invention improves upon the prior art by providing a mountable equipment rack having a plurality of legs connected to a cross member. The invention includes at least one equipment support bar for placing equipment such as bicycles and skis on the mountable equipment rack. The legs include a pair of front legs and a pair of rear legs. The rear legs and the equipment support bar are rotatable relative to the cross member for storing in a compact position or maneuvering to a desired position, depending on the size of the trunk onto which the equipment rack will be placed. The front legs are fixed relative to the cross member. [0007] Particular embodiments of the invention also include a plurality of strap housing assemblies coupled to the legs that have retractable straps capable of securing the mountable equipment rack to a vehicle. Each strap housing assembly includes a cover, a retractable strap and a securing mechanism. Each retractable strap can be pulled out to couple a leg to the trunk of a vehicle and retracted back into the strap housing assembly. Therefore, the mountable equipment rack is easily placed onto and removable from a trunk of a vehicle. [0008] Accordingly, it is an object of the invention to provide an equipment rack that is easily mountable on vehicles. One embodiment of the invention provides an equipment rack that is adjustable to conform to different types of vehicles, and which has structural members that are adjustable to fit different mounting positions. Other embodiments of the invention may also provide an equipment rack that is easily securable to a vehicle for the transportation of equipment. The equipment rack may also be adjustable for compact storage. Further objects and features of the invention will be apparent from the drawings, the detailed description and the claims. BRIEF DESCRIPTION OF THE DRAWINGS [0009] [0009]FIG. 1 is a perspective view of a mountable equipment rack in a secure position on the trunk of a vehicle; [0010] [0010]FIG. 2 is a side view of the mountable equipment rack with an equipment support bar in an extended position; [0011] [0011]FIG. 3 is a front view of the mountable equipment rack; [0012] [0012]FIG. 4 is an additional front view of the mountable equipment rack; [0013] [0013]FIG. 5 is a rear view of the mountable equipment rack; [0014] [0014]FIG. 6 is an additional rear view of the mountable equipment rack; [0015] [0015]FIG. 7 is a perspective view of the mountable equipment rack in a stored position; [0016] [0016]FIG. 8 is a close-up perspective view of a positioning assembly of the mountable equipment rack; [0017] [0017]FIG. 9 is an additional close-up view perspective of a positioning assembly of the mountable equipment rack; and [0018] [0018]FIG. 10 is an overhead view of a positioning assembly of the mountable equipment rack. DETAILED DESCRIPTION OF THE EMBODIMENTS [0019] [0019]FIG. 1 shows a mountable equipment rack 10 having a cross member 12 disposed between a plurality of arcuately oriented legs, secured to the trunk of a vehicle. The plurality of legs includes a first rear leg 14 , a second rear leg 16 , a first front leg 18 , and a second front leg 20 . Although the legs are shown as arcuately shaped in FIG. 1, they may be straight or curved, and additionally the legs do not all need to be of the same shape. Each leg is coupled at one end to the cross member 12 . The mountable equipment rack 10 also includes at least one strap housing assembly 22 . Each strap housing assembly 22 includes a cover 24 , a retractable strap 26 and a securing piece 28 . As shown in FIG. 1, each retractable strap 26 is extended so that the securing piece 28 attached to each retractable strap 26 releasably secures the mountable equipment rack 10 to a part of the trunk of the vehicle. Each strap housing assembly 22 may also include a knob that can be turned to facilitate the retraction of a retractable strap 26 when not in use. The retractable straps 26 may be made of any material that is of sufficient strength to provide secure support for the equipment rack on a vehicle. The number of strap housing assemblies 22 used to secure the mountable equipment rack 10 to a trunk varies depending on the level of security desired. The invention contemplates that any number of strap housing assemblies 22 may be used to releasably secure the mountable equipment rack 10 to a vehicle. A strap housing assembly 22 is coupled to the mountable equipment rack 10 by either removably attaching to a leg or by fixedly attaching to a leg. A leg on which a strap housing assembly 22 is placed may have one or many of such strap housing assemblies. The invention contemplates that at least one strap housing assembly 22 is used to releasably secure the mountable equipment rack 10 to a vehicle. In one embodiment, each leg includes at least one strap housing assembly 22 . In another embodiment, the invention includes more legs than there are strap housing assemblies 22 , such that not every leg has a strap housing assembly coupled thereto. [0020] The mountable equipment rack 10 also includes a first axially oriented positioning assembly 30 disposed on said cross member 12 and a second axially oriented positioning assembly 32 , also disposed on said cross member 12 . Each of the axially oriented positioning assemblies 30 and 32 include a rotatable member 34 having a first rotatable ring 36 and a fixed member 38 . The rotatable member 34 of the first axially oriented positioning assembly 30 is coupled to the first rear leg 14 . Similarly, the rotating member 34 of the second axially oriented positioning assembly 32 is coupled to the second rear leg 16 . The fixed member 38 of the first axially oriented positioning assembly 30 is coupled to the first front leg 18 , and the fixed member 38 of the second axially oriented positioning assembly 32 is coupled to the second front leg 20 . Thus, each of the fixed members 38 fixedly couple a front leg to the cross member 12 . [0021] Each axially oriented positioning assembly 30 and 32 may also include a support bar member 48 having a second rotatable ring 50 . The mountable equipment rack 10 also includes at least one equipment support bar 46 coupled to the support bar member 48 . In one embodiment, the mountable equipment rack 10 includes two equipment support bars 46 , each equipment support bar 46 coupled to a support bar member 48 having a second rotatable ring 50 . In this embodiment, each support bar member 48 and second rotatable ring 50 are axially coupled to the cross member 12 . Therefore, the support bar members 48 and second rotatable rings 50 to which they are attached rotate together to allow the equipment support bar 46 to rotate relative to the cross member 12 . All first and second rotatable rings 36 and 50 have a plurality of holes. The plurality of holes allow a locking pin to be inserted between said holes to lock the first and second rotatable rings in place so that they can no longer rotate when the mountable equipment rack 10 is in use. Thus, the locking pins prevent the rings from moving, thereby securing the rear legs 14 and 16 as well as the equipment support bar 46 in place. [0022] [0022]FIG. 1 also shows a plurality of traction members 52 coupled to distal ends of each of the front and rear legs. These distal ends are opposite to the ends of the front and rear legs that couple to the cross member. The traction members 52 provide additional support for each of the front and rear legs and prevent movement of the legs when mounted on a vehicle. The traction members 52 also prevent damage to the vehicle on which the mountable equipment rack 10 is placed, such as denting, scratching or the chipping of paint. The plurality of traction members 52 may be spherical in shape and may be made of rubber. However, it is to be understood that the plurality of traction members may be of any shape and may be made of any material suitable for the purposes for which the traction members are used. For example, the traction members may be made of foam and made be square in shape. [0023] [0023]FIG. 2 shows a side view of the mountable equipment rack 10 . In FIG. 2, the retractable straps 26 and securing mechanisms 28 are shown retracted into the strap housing assemblies 22 such that they are not securing the mountable equipment rack 10 to a trunk of a vehicle. FIG. 3 shows a front view of the mountable equipment rack 10 . Both views in FIG. 2 and FIG. 3 show the positioning of the front and rear legs as they would generally be if they were positioned on a vehicle for storage of equipment. FIG. 4 shows a rear view of the mountable equipment rack 10 . FIG. 4 also shows the range of movement over which the equipment support bars 42 can rotate relative to the cross member 12 . FIG. 5 shows a rear view of the mountable equipment rack 10 , in a position similar to that of FIG. 3. [0024] [0024]FIG. 6 shows a front view of the mountable equipment rack 10 with the equipment support bars 46 rotated at a higher angle than that shown in FIGS. 2 and 3. FIG. 6 also shows the ability of the equipment support bars 46 to rotate relative to the cross member 12 . By removing the locking pins that hold the rotatable rings together, the equipment support bars 42 are able to rotate relative to the cross member 12 to a position as desired by a user. FIG. 7 shows the mountable equipment rack 10 in a stored position. In this stored position, the locking pins, when removed from the rotatable rings, allow the rear legs and equipment support bars to rotate to a position in which the front and rear legs are positioned close together and the equipment support bars are positioned close to both the rear and front legs. By placing the locking pins back through the holes in the rotatable rings, the mountable equipment rack 10 can be easily carried in the position shown in FIG. 7 and stored. [0025] The cross member 12 of the mountable equipment rack 10 is made of metal. In one embodiment, the metal used to make the cross member 12 is aluminum. The front and rear legs of the mountable equipment rack 10 are made of any material strong enough to support articles placed on the equipment support bar 46 . In one embodiment, the materials used to make the front and rear legs are a substance comprising 80% polypropylene and 20% glass. The rotatable rings may also be made of a metal, for example aluminum. [0026] [0026]FIG. 8 is a close-up perspective view of a positioning assembly on the cross member 12 of the mountable equipment rack 10 . As described above, each positioning assembly includes a support bar member 48 having a second rotating ring 50 , a rotatable member 34 having a first rotating ring 36 , and a fixed member 38 . The fixed member 38 includes a front leg, while the rotatable member 34 includes a rear leg. The fixed member 38 and front leg are fixedly coupled to the cross member 12 and do not rotate around the cross member 12 . The rotating member 34 and rear leg are rotatably coupled to the cross member 12 . The support bar member 48 couples to an equipment support bar 46 . FIG. 9 is a close-up perspective view of a positioning assembly with the equipment support bar 46 positioned lower than that shown in FIG. 8, and the rear leg also positioned lower than that shown in FIG. 8. [0027] [0027]FIG. 10 is an overhead view of a positioning assembly of the mountable equipment rack 10 . This view shows the equipment support bar 46 and support bar member 48 in a locked position, with a locking pin placed through the second rotating ring 50 of the support bar member 48 and through the first rotating ring 36 of the rotatable member 34 . This secures both the rear leg and the equipment support bar 46 for sturdy use on a vehicle. [0028] The foregoing presents particular embodiments of the invention. However, various alternatives fall within the scope of the invention. For example, the retractable straps of the strap housing assemblies may be elastic bands that stretch from a relaxed position to couple the legs to a vehicle. Also, the securing pieces may include hooks that releasably secure the legs to a vehicle. In another example, the rear legs may fixedly couple to the cross member while the front legs rotatably couple to the cross member. Consequently, the invention is not limited to the specific embodiments described herein.	A trunk-mountable equipment rack includes a frame having a cross member and a plurality of legs. The legs have straps attached that are capable of extending to couple the legs to the trunk of a vehicle. These straps allow the equipment rack to be placed on and secured to different sizes and shapes of trunks of vehicles. The invention also includes support bars for securing equipment to the equipment rack for transportation on a vehicle.	1
FIELD OF THE INVENTION [0001] The present invention relates to concrete forming panels, and in particular, relates to concrete forming panels having a series of interlocking panel sections mechanically secured to adjacent panel sections. BACKGROUND OF THE INVENTION [0002] Concrete forming panels are commonly used in the construction industry to quickly assemble a concrete form. Forming panels have been used for many years, and often have a plywood concrete engaging face with a reinforcing structure secured on a rear side thereof to support the concrete load. [0003] It is also known to use a concrete forming panel fabricated from aluminum extrusions where these extrusions are mechanically connected to define the forming panel. One such example of this structure is illustrated in Canadian Patent 2,141,463 that is owned by the present applicant. In this reference, the concrete forming panel is broken into a number of panel sections where each section is an aluminum extrusion. The aluminum extrusions are connected to an adjacent extrusion by a hook and slot arrangement, and by a curved flange provided adjacent a rear edge beneath the hook and slot arrangement. This curved flange is connected to a structural member of the adjacent panel section to mechanically secure the two sections together and to maintain a predetermined angle of the forward face of each of these panels. With this arrangement, a reinforced box-like structure is provided beneath the mechanical securement (hook and slot) of the two panels at the forward face. [0004] With the structure as disclosed in Canadian Patent 2,141,463 the connected panel sections required additional support and the panel sections were prone to deflection at intermediary positions, even if the rear face of the panel was supported. [0005] It would be desirable to provide a concrete forming panel having the desirable characteristic of being assembled from a series of extrusions while providing a panel that is easy to assemble and is relatively stiff. SUMMARY OF THE INVENTION [0006] A concrete forming panel according to the present invention comprises at least first and second interlocking panel sections having a mechanical hinge connection joining the sections at an intermediate position extending in the length of the forming panel. The mechanical connection comprises a hook portion on the first panel received in a slot portion of a second panel and the mechanical connection includes a stop abutment of the hinge connection that is engaged when the panel sections are joined and aligned to form the forming face of the panel. The panel includes a series of brace members extending across the panel section on a rear surface thereof. Each brace member maintains engagement of any stop abutments and provides a rear support of the mechanical connection opposing deflection of the forming face towards the brace member. [0007] In an aspect of the invention, the second panel below the slot includes a downwardly extending web member having a distal end thereof in engagement with the series of brace members to provide the rear support of the mechanical connection. [0008] In a further aspect of the invention, the downwardly extending web member includes a bead portion at the distal end in engagement with the series of braces. [0009] In a further aspect of the invention, the panel includes on either side of the length thereof, downwardly extending side rails and each of the series of brace members extend between and are secured to the side rails. [0010] In a further aspect of the invention, the side rails include an inwardly extending flange portion, and the inwardly extending flange portion supports the brace members at opposite ends thereof. [0011] In a further aspect of the invention, the brace members have an interference fit between said side rails and any of the bead portions maintaining the panel in an assembled configuration. [0012] In a preferred aspect of the invention, the forming panel includes at least a third panel section connected as an intermediary between the first and second panel sections. [0013] In yet a further aspect of the invention, a pair of end rails close opposed ends of the concrete forming panel and are secured to the at least two panel sections. [0014] In yet a further aspect of the invention, the brace members are tubular extrusion members fixedly secured to the side rails. BRIEF DESCRIPTION OF THE DRAWINGS [0015] Preferred embodiments of the invention are shown in the drawings, wherein: [0016] FIG. 1 is a rear perspective view of the concrete forming panel; [0017] FIG. 2 is an exploded perspective view of the concrete forming panel shown in FIG. 1 ; [0018] FIG. 3 is a partial exploded assembly view of a concrete forming panel having two panel sections; [0019] FIG. 4 is a view similar to FIG. 3 with the concrete forming panel in the assembled condition; [0020] FIGS. 5 , 6 and 7 show details of the particular mechanical hinge and the stop abutment that allows the panel to form a planar front face as shown in FIG. 7 ; [0021] FIG. 8 is a view of a concrete forming panel having first and second outer panel sections and an intermediary panel section; and [0022] FIG. 9 is the panel of FIG. 8 , but in an assembled form. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] The concrete forming panel 2 shown in FIGS. 1 and 2 includes three panel sections; namely side panel section 4 , intermediary panel section 8 and side panel section 6 . In the embodiment shown, the intermediary panel 8 includes a slot 46 adjacent one edge thereof for receiving the hook 40 of the side panel section 6 . The opposite edge of intermediary panel section 8 includes a hook 40 that is received within the slot 46 of the side panel section 4 . Details of the hook and slot and their mechanical connection are shown in FIGS. 3 and 4 . [0024] The concrete forming panel 2 , when the various panel sections are interconnected, has a series of brace members 16 , 18 and 20 that engage a rear face of the panel sections and also extend between the side panel sections 4 and 6 . These brace members have a slight interference fit with the connected panel sections and the braces maintain the mechanical connections at the front face of the panel in locked engagement and maintain alignment of the panel section to define the planar front face of the forming panel. [0025] The side panel sections 4 and 6 as shown in FIGS. 1 and 2 include integral side edges 4 a and 6 a that define the sides of the panel and extend in the length of the panel. The ends of the panel are closed by the end rails 10 and 12 . The concrete forming panel 2 includes a plurality of connecting ports 30 provided in the sides of the panel to allow connection to adjacent panels. Preferably these connecting ports include a reinforcing insert to reduce wear of the ports due to fasteners. [0026] As shown in FIG. 3 , the hook 42 is received in the slot 46 and this generally requires it to be moved to the angular position as shown in FIG. 5 . In this position, the hook is easily received within the slot 46 and will generally be supported by the upper lip 50 at one edge of the side panel 4 . The side panel 6 is rotated in a clockwise direction to the planar configuration of the panel as shown in FIG. 7 . The side panel section 6 and the side panel section 4 have now aligned and form the planar front face of the concrete forming panel 2 . [0027] Beneath the slot 46 , the extrusion includes a downwardly extending web member 52 that terminates in a bottom flange or bead portion 54 . This web and bottom flange support the slot 46 and, when engaged with the bracing member 18 , oppose downward deflection of the top surface of the panel 4 . This can be appreciated from a review of FIG. 4 . [0028] This particular support of the side panel section 4 supports the free end of this panel section and also supports the hook 40 of the side panel section 6 . In the embodiment of FIGS. 3 through 7 , the concrete forming panel has only the two side panel sections 4 and 6 and the one intermediary support provided by the web 52 and the bottom flange or bead 54 is sufficient. [0029] In the embodiment shown in FIGS. 8 and 9 , an additional intermediary panel 8 has been provided having a similar slot 46 adjacent one edge thereof and a hook 42 provided at the opposite longitudinal edge. In this case, the intermediary panel section 8 also includes a central support generally shown as 60 which includes the downwardly extending web 62 and the lower flange 64 . At the edge of the intermediary panel section 8 is the similar web 52 and lower flange 54 for supporting of the slot 46 . [0030] From a review of the assembled panel of FIG. 9 , it can be seen that each hook and slot arrangement is directly supported by a downwardly extending web 52 and a flange 54 . These members, in combination with the structure for forming of the slot 46 , form an I-beam type structure that provides excellent support for the mechanical connection. The intermediary panel section 8 includes the additional support 60 which also engages the bracing member 18 . The mechanical connection of intermediary panel section 8 and side panel section 4 a is also positively supported by a web 52 and a lower flange 54 . The modified side panel section 4 a also includes a downwardly extending web 72 and a bottom flange 74 that provides intermediary support between the side portion 76 and the location of the slot 46 at one edge of the modified panel section 4 a. With this arrangement, a series of downwardly extending webs and associated flanges engage the various bracing members 16 , 18 and 20 as shown in FIGS. 1 and 2 , and thus oppose any downward deflection of the front face of the concrete forming panel 2 . [0031] Additional braces can be added as required. The side panel sections 4 , 4 a and 6 as shown in the drawings have relatively stiff sides at the edges of the concrete forming panel, and the side members 76 and 80 shown in FIG. 9 serve to retain and secure the bracing member 18 . The side member 76 includes an inwardly extending flange 78 that engages and provides support for the base of the bracing member 18 . Member 80 includes inwardly extending flange 82 that supports the opposite end of the bracing member 18 . Bracing member 18 can be forced into the gap at the rear of the panel and preferably has a slight interference fit with the remaining components to maintain the assembled concrete forming panel in a desired assembly for final securement. The bracing members 16 , 18 and 20 are typically welded to the side rails of the panel, namely 76 and 78 , as shown in FIG. 9 . This arrangement positively maintains the trapezoidal bracing members in the interior of the concrete forming panel at the open rear surface thereof. The end rails 10 and 12 are also preferably welded to the panel sections by a series of tack welds. [0032] Other arrangements for securing of the panel sections to each other can be used, however the use of tack welding simplifies the manufacturing steps and also reduces the cost to manufacture the panel. As can be appreciated, the particular design of the concrete forming panel allows convenient assembly of the various components and these components can generally be maintained in their assembled condition in preparation for welding. The insertion of the bracing members maintains the panel sections in preparation for final securement. Typically the end rails are merely located at the ends of the extrusions and are tack welded in place. [0033] The particular hook and slot arrangement does provide a positive stop face that limits angular movement of adjacent panels, and this stop face assists in defining the planar front face of the concrete forming panel. A very small seam may be visible at this stop face, however this seam is under compression and as such any joining line is quite thin. This improves the finished surface of the concrete. The use of aluminum extrusions also results in the concrete forming panel being easily separated from the concrete and a clean finished surface being defined. [0034] When these concrete forming panels are in place and under load, they are connected to adjacent panels using the various ports 30 . Suitable collars can be inserted in the ports, and the panels can be assembled using steel-type connecting pins and wedges. The assembled panels can then be supported by further structural members provided behind the panels. When the panels are loaded due to the concrete load, this load tends to further tighten the mechanical joint and to tighten the securement of the panel sections. The braces positively support the rear surface of the forming face. With this arrangement, the seam at the junction of the hook and slot is under compression and the seam is quite small. [0035] The particular arrangement shown and described allows a series of intermediary panels to be connected between the side panels, and thus panels of different widths are easily produced. The mechanical connection is basically the same, and the number of intermediary supports may be increased. Furthermore, it can be appreciated as shown with respect to the side panel section 4 a, these side panel sections can also be of different widths and therefore the actual width of the concrete forming panel can easily be modified to meet a particular need of a contractor or a client. With wider concrete forming panels, it may be appropriate to also provide some tack welding of the bracing members to the various support members where they engage or pass over the bracing members. [0036] The panel sections as described extend in the length of the panel; however it is also possible to use shorter panel sections extending in the width. This arrangement is less desirable as the number of seams increase and the bracing would then extend in the length. [0037] It has been found that this concrete forming panel, using the mechanical connection of a plurality of sections, provides a structure which is cost effective to produce and provides excellent characteristics with respect to finish and durability. The design allows easy modification for building of concrete forming panels in different widths and lengths as may be required. [0038] It is possible to modify the individual panel sections, the bracing members and end rails to provide appropriate support. For example, where loads are higher, the bracing members may be slightly wider or more bracing members provided to provide proper support. The desired trapezoidal shape of the brace members is also convenient for a worker to grasp and is of assistance in assembly and dismantling. [0039] Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.	Concrete forming panels according to the present invention are formed using a series of interlocking panel sections mechanically connected at a forward face of the panel. The mechanical connection uses a hook portion of one section received in a slot portion of an adjacent section with a pivot and stop relation defining the planar forming face. A series of brace members extend across the panel sections on a rear surface and maintain engagement of the panel sections and reinforce the panel sections against deformation of the forming face during use of the panel. The arrangement is economical to manufacture in many different sizes as may be required by a customer. Some welding is used, however the mechanical connection greatly reduces the amount of welding required. Replacement sections can easily be used to repair damaged panels.	4
FIELD OF INVENTION The present invention relates to air bearings, and in particular to air-bearings used in conjunction with hard disk drive spindle motors. The invention further relates to air bearings used in disk drive spindle motors having an insideout motor design, or alternatively, an underslung motor design. BACKGROUND OF THE INVENTION Disk drive memory systems store digital information on magnetic disks. The information is stored in concentric tracks divided into sectors. The disks themselves are rotatably mounted on a spindle, and information is accessed by means of read/write heads mounted on pivoting arms able to move radially over the surface of the disk. This radial movement of the transducer heads allows different tracks to be accessed. Rotation of the disk allows the read/write head to access different sectors on the disk. In operation, the disk or disks comprising the magnetic media are rotated at very high speeds by means of an electric motor generally located inside the hub that supports the individual disks. Bearings mounted inside the hub allow the hub to rotate about a fixed shaft. These bearings are typically ball bearings or fluid bearings. Bearings having a fluid lubricant are desirable for disk drive applications because of their inherently low, nonrepeatable run out and low acoustic noise. However, these bearings suffer from several shortcomings. For instance, the oil used to provide the fluid bearing has a tendency to leak and outgas. Therefore, such bearings may lead to contamination of the interior of the disk drive. Such contamination may cause a failure of the drive in the form of data errors. Bearing systems incorporating an oil lubricant also have a limited maximum rotational speed due to their large power consumption at high speeds. Alternative designs have utilized air bearings having grooved surfaces to generate areas of increased pressure when the surfaces of the bearing move in opposition to each other. However, such designs have typically had only a unidirectional thrust mechanism, and therefore the disk drive can only be operated when the device is in certain orientations (e.g. upright), or the device cannot withstand shock in certain directions (e.g. the axial direction). Furthermore, previous designs have featured relatively small-diameter radial bearing surfaces, resulting in bearings that have inadequate stiffness. Therefore, conventional air bearing designs result in a bearing that cannot maintain the rotating components in a precise relationship to the stationary components when bearings constructed in accordance with those designs are subjected to external forces. Adequate stiffness is difficult to achieve in an air bearing because air has a viscosity that is much lower than the viscosity of oil or other conventional lubricants. Other bearing designs have utilized pressurized gas as a lubricating fluid. Such designs require an external supply of pressurized air and so would not be suitable for a disk drive application. Air is desirable as a bearing lubricant because its use removes concerns about leakage and outgassing. In addition, the viscosity of air does not vary with changes in temperature as much as does the viscosity of oil or other lubricants. Furthermore, air bearings provide lower acoustical noise characteristics and less non-repeatable run out than ball-bearing designs and lower power consumption due to decreased friction than oil-filled bearings. However, known designs using air as a lubricant have used extremely high rotational speeds or extremely tight internal clearances or both to increase the stiffness of the bearing in order to achieve stiffness levels that are comparable to the stiffness of oil filled bearings. A bearing that lacks stiffness will allow the rotating disks to deviate from the desired alignment when the drive is subjected to external forces. High rotational speeds and tight clearances have been necessary in conventional air bearings because the viscosity of air is approximately 1/700 that of oil. However, increased rotational speeds generally reduce the storage capacity of the disk drive because of limitations in read/write channel data rates. Also, the tight internal clearances typically employed by known air-bearing designs increase manufacturing costs tremendously. Other air bearing designs are physically larger in size than conventional oil filled bearings, and are therefore unsuitable for small form factor drives. Also, these other designs have a relatively large number of parts, increasing manufacturing costs. It would be desirable to provide a bearing system for a disk drive motor assembly that utilized air as the fluid medium between bearing surfaces. In addition, it would be desirable that such a device be easy to manufacture in large volumes and at low cost. Furthermore, it would be advantageous to provide a bearing having adequate stiffness, while providing enhanced performance, lowered power consumption and wear and tear, and having a longer life than conventional bearings. SUMMARY OF THE INVENTION The present invention relates to an air bearing apparatus for use in hard disk drive spindle motors. In particular, the invention provides an air bearing having a large surface area, to increase the stiffness of the bearing, while allowing the bearing to be manufactured with conventional oil filled bearing type tolerances. In a preferred embodiment, the air bearing is used in conjunction with an inside out underslung motor to further increase the area of the bearing. In addition, the present invention includes a method for providing a disk drive device with a bearing having air as its lubricating fluid, and providing adequate levels of stiffness while being capable of manufacture using conventional tolerances. The device includes a computer hard disk drive having a base. Affixed to the base is a stationary shaft having an enlarged bearing portion and a spindle portion. The diameter of the bearing portion of the shaft is approximately four times greater than that of the spindle portion. Enveloping the bearing portion of the stationary shaft is a hub having an internal cylindrical bore that is concentric to the stationary shaft and adjacent to the bearing portion of that shaft. The top portion of the cylindrical bore is adjacent to the top of the bearing. Also interconnected to the hub is a thrust plate, concentric to the stationary shaft and adjacent to a bottom of the bearing. Between the cylindrical bore in the hub and the bearing portion of the stationary shaft, and between the thrust plate and the bottom of the bearing, are fluid filled gaps. In a preferred embodiment, the fluid filling these gaps is air. In a further preferred embodiment of the device, the bearing has a plurality of grooves on the top, side and bottom surfaces of the bearing. In a most preferred embodiment, the device further includes grooves on the top, side, and bottom surfaces of the bearing that are arrayed in a herring bone pattern, and that have a square or semi-circular cross section. In a further embodiment, a disk storage drive is disclosed having a stationary shaft with a bearing portion having a length that is less than about 90% of its diameter. The device further has a hub portion defining an interior volume, and a sleeve interconnected to the hub. The sleeve is concentric to the stationary shaft and adjacent to the bearing, and has an annular top portion concentric to the stationary shaft and adjacent to a top of the bearing. An annular thrust plate is also interconnected to the hub such that it is concentric to the stationary shaft and adjacent to a bottom of the bearing. Between the sleeve and the bearing portion and between the annular thrust plate and the bearing portion are fluid filled gaps. According to this embodiment, the bearing portion of the stationary shaft substantially occupies the internal volume of the hub. In an additional embodiment of the present invention, a motor assembly for use in a magnetic disk drive system is disclosed. The assembly features a base, a cylindrical bearing interconnected to the base, a rotatable hub disposed about and concentric to the bearing, a stator interconnected to the base and disposed radially about an axis of rotation of the hub, and magnetic means interconnected to the hub. The interior of the hub has a surface defining a cylindrical volume that is substantially filled by the bearing. An annular thrust plate is adjacent to a bottom of the bearing. In a preferred embodiment, a cylindrical sleeve member is affixed to the hub and interposed between the cylindrical volume of the hub and the bearing. In a further preferred embodiment of the invention, the motor assembly stator defines an inner diameter, and the magnetic means is disposed about and outside of that diameter. In an alternative preferred embodiment, the stator defines an outer diameter, and the magnetic means is disposed within the diameter of the stator. In a most preferred embodiment, the sleeve member is made from a ferromagnetic material. In another embodiment, the present invention provides an air bearing motor assembly having a base, a stationary shaft affixed to the base, and a stationary annular bearing disposed about the shaft, wherein the bearing has an outer diameter that is at least about four times the diameter of the shaft. The air bearing motor further has a rotatable hub disposed about the shaft, and a sleeve affixed to the inside of the hub. The sleeve has an upper annular portion and a cylindrical side portion, with a diameter that is slightly greater than the diameter of the bearing. The bottom portion of the sleeve extends beyond a bottom portion of the hub. Interconnected to the hub is an annular thrust plate adjacent to a bottom of the sleeve. A stator is affixed to the base such that it can interact with magnetic means interconnected to the hub. In yet another embodiment, a disk storage unit is provided having a cylindrical bearing. The cylindrical bearing has a top, a side, a bottom and a diameter. A hub having a cylindrical inner surface with a diameter that is larger than the diameter of the bearing encloses the top and side of the cylindrical bearing such that a fluid filled gap is formed. The volume defined by the cylindrical inner surface is substantially equal to a second volume defined by the bearing. Furthermore, the volume of the cylindrical inner surface of the hub is substantially equal to a volume described by an outer surface of the hub. An annular thrust plate interconnected to the hub is positioned such that a fluid filled gap is formed between the thrust plate and the bottom of the bearing. In a preferred embodiment, the volume of the cylindrical inner surface of the hub is at least about 80% of the volume described by the outer surface of the hub. In a further embodiment of the present invention, a method is provided for supplying an air filled bearing for use in a disk drive spindle motor. The bearing is enclosed within a closely fitting surface interconnected to a rotatable hub. The volume enclosed by the hub is substantially filled by the bearing to maximize the surface area of the bearing. In a preferred embodiment, the side, top and bottom surfaces of the cylindrical bearing are provided with grooves to increase air pressure in the medial portions of the bearing when the hub is rotating about the stationary shaft. Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cutaway view of a disk drive spindle air bearing having an underslung motor design in accordance with one embodiment of the present invention; FIG. 2 is a side view of a spindle bearing having a grooved surface in accordance with one embodiment of the present invention; FIG. 3 is a top view of a spindle bearing having a grooved surface in accordance with one embodiment of the present invention; FIG. 4 is a detail illustrating the geometry of an individual groove comprising the grooved surface illustrated in FIG. 3 in accordance with one embodiment of the present invention; and FIG. 5 is a cutaway view of a disk drive spindle air bearing having an inside-out underslung motor in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, a disk drive spindle air bearing is provided. With reference to FIG. 1, an air bearing having an underslung motor design constructed in accordance with one embodiment of the present invention is generally identified as air bearing 104 . The air bearing 104 generally comprises a base assembly 108 and a hub assembly 112 . The base assembly 108 generally comprises a base 116 , only the center portion of which is illustrated in FIG. 1, a stator assembly 120 and a spindle 124 . The spindle 124 includes an enlarged bearing portion 128 . The stator assembly 120 generally comprises laminations 132 and coils 136 . The laminations 132 are affixed to the base 116 and arranged radially about the longitudinal axis 140 of the spindle 124 , which is itself affixed to the base 116 . The coils 136 are disposed about the laminations 132 . In a preferred embodiment, the base 116 comprises cast aluminum, the spindle 124 comprises machined steel, the laminations 132 comprise thin sheets of a ferromagnetic material stacked on top of one another, and the coils 136 comprise an electrically conductive wire having an insulating exterior, wound about the laminations 132 . The hub assembly 112 comprises the hub 144 , sleeve 148 , thrust plate 152 , back iron 156 , and magnets 160 . The hub 144 has an internal cavity enclosing the bearing portion 128 of the spindle 124 and the stator assembly 120 . The hub features a flange 164 onto which magnetic storage disks (not shown) may be stacked and supported. The hub 144 also features a clamp 168 to which a retainer (not shown) may be affixed to retain the magnetic disks (not shown). The upper portion of the internal cavity of the hub 144 defines a first cylindrical space having a length and a first diameter. Affixed to this upper portion of the cavity of the hub 144 is the sleeve 148 . The interior of the sleeve 148 has an annular upper surface 172 and a cylindrical side surface 176 . The exterior of the sleeve 148 is sized such that it can be securely mounted within the upper portion of the internal cavity of the hub 144 , while the interior of the sleeve 148 , which generally defines a cylindrical volume, has dimensions that are slightly larger than the length and diameter of the spindle bearing 128 . Thrust plate 152 has an annular shape, and is adjacent to the bottom of the sleeve 148 . The thrust plate 152 may be affixed to the hub 144 , or to the sleeve 148 . A skirt portion 180 of the hub 144 defines a second cylindrical space in the interior of the hub 144 . Affixed to the hub 144 , and located within the skirt portion 180 of the hub 144 is the back iron 156 . The back iron 156 is generally cylindrical in shape and is preferably made from a ferromagnetic material such as iron. Affixed to the back iron 156 are a plurality of magnets 160 . The positioning of the magnets on the interior surface of the back iron 156 and within a circumference generally defined by the skirt portion 180 of the hub 144 positions them radially about the stator assembly 120 . In operation, the hub assembly 112 rotates about the longitudinal axis 140 of the spindle 124 . The impetus for this rotation is provided by the motor 182 , which generally comprises the stator 120 , and the magnets (or rotor) 160 . Energy to impart this motion is provided by an electrical current sent through the coils 136 of the stator assembly 120 , which creates a magnetic field about and through the laminations 132 . The interaction of this magnetic field with the magnetic field of the magnets 160 of the hub assembly 112 causes the hub assembly 112 to rotate relative to the base assembly 108 . While the hub assembly 112 is rotating relative to the base 116 , resistance to forces along the longitudinal axis 140 of the spindle 124 is provided by high pressure air in the upper 184 and the lower 188 annular spaces. These areas of high pressure air are created by a laminar air flow that is created when the upper surface 172 of the sleeve 148 rotates relative to the upper annular surface 192 of the spindle bearing 128 , and the thrust plate 152 rotates relative to the lower annular surface 196 of the spindle bearing 128 . an Resistance to radial forces is provided by high pressure air in the cylindrical gap between the side of the spindle bearing 128 and the cylindrical side surface 176 of the sleeve 148 . This high pressure air is created by a laminar air flow created when the sleeve 148 rotates relative to the spindle bearing 128 . As can be seen from the embodiment illustrated in FIG. 1, the spindle bearing 128 is relatively large, and it substantially fills the enclosed volume defined by the upper interior surfaces of the hub 144 . Furthermore, the spindle bearing 128 has a volume slightly less than the enclosed volume defined by the interior surfaces located between the sleeve 148 and the thrust plate 152 on the one hand, and the spindle bearing 128 on the other hand. This large size is advantageous, because it increases the stiffness of the bearing. The relatively large size of the bearing allows it to have a stiffness that approximates the stiffness of a conventional oil bearing, even when the fluid filling the bearing is air. This is so even though the viscosity of air is approximately 1/700 the viscosity of oil. Furthermore, the disclosed design allows an air bearing having suitable stiffness characteristics to be manufactured using conventional oil-filled bearing tolerances. In addition, the disclosed design provides adequate stiffness even at conventional disk drive rotational speeds (e.g., 7200 rpm). In accordance with one embodiment of the present invention, the side surface 200 of the spindle bearing 128 is grooved. With reference now to FIG. 2, the radial pressure grooves 204 provided according to this embodiment generally comprise parallel rows of grooves having a herring-bone shaped pattern. Preferably, the cross-section of the radial pressure grooves 204 is square, although suitable radial pressure grooves 204 can be constructed using other profiles, such as semi-circular or triangular. In a preferred embodiment, the ratio of the width of the radial pressure grooves 204 to the land 208 between the grooves is 1:1. The radial pressure grooves 204 increase the air pressure in the annular space defined by the gap between the cylindrical side surface 176 of the sleeve 148 and the side surface 200 of the spindle bearing 128 when the hub assembly 112 rotates relative to the base assembly 108 . In the illustrated embodiment, the grooves are designed so that the air pressure in the aforementioned annular space is increased when hub assembly 112 rotates about the spindle bearing 128 in the direction in which the herring-bone pattern points. Specifically, the rotation of the sleeve 148 relative to the spindle bearing 128 creates a flow of air about the spindle bearing 128 in the same direction that the sleeve 148 is rotating. The radial bearing grooves 204 tend to pull air towards the center of each row of grooves 204 , thus creating areas of high pressure. Because of the increased air pressure along the center lines of each row of radial bearing grooves 204 , the radial stiffness of the bearing itself is improved. In addition to the embodiment illustrated in FIG. 2, the present invention encompasses radial bearing grooves 204 having other configurations. Thus, radial bearing grooves could be provided in any pattern generally adapted to drawing air to a center of the side surface 200 of the spindle bearing 128 , so that an area of high pressure air is created. Accordingly, acceptable groove patterns include a single row a of grooves in a herring-bone shaped pattern, opposing arrays of diagonal grooves, a spiraling pattern of grooves, or varying arrangements of arcuate grooves. In addition, the present invention includes within its scope the use of vanes or other raised areas on the side surface 200 of the spindle bearing 128 to perform the same function of pumping air to an intermediate area of the side surface 200 of the spindle bearing 128 as do the grooves in the illustrated embodiment. Any pattern or arrangement of grooves or raised surfaces suitable for increasing air pressure along the side surface 200 of the spindle bearing 128 may be used. Furthermore, grooves and vanes or protrusions may be used in combination. Although the embodiment illustrated in FIG. 2 shows grooves on the side surface 200 of the spindle bearing 128 , the grooves may alternatively be provided on the interior of the side surface 176 of the sleeve 148 . As described above, the function of the grooves is to create high pressure areas in a middle portion or portions of the side surface 200 of the spindle bearing 128 to increase the stiffness of the bearing in a radial direction. Therefore, the shape and pattern of provided grooves may be similar to those that would be provided on the spindle bearing 128 . However, the direction of, for example, a herring-bone pattern, would be opposite that of grooves provided on the spindle bearing 128 . Therefore, the herring-bone pattern would point away from the direction of rotation of the hub assembly 112 about the spindle 124 of the base assembly 108 . Again, this is to draw air to an intermediate portion or portions of the side surface 176 of the sleeve 148 . Furthermore, as described above, the features provided to pump air to the intermediate portions of the sleeve 148 need not be grooves, but may also be vanes or other protrusions. Referring now to FIG. 3, the lower annular surface 196 of spindle bearing 128 according to an embodiment of the present invention is illustrated. According to the illustrated embodiment, a plurality of thrust bearing grooves 304 are provided on the lower annular surface 196 of the spindle bearing to increase the air pressure in the lower annular space 188 when the hub assembly 112 rotates relative to the base assembly 108 . In the illustrated embodiment, the grooves are designed so that the air pressure in the lower 188 annular space is increased when the hub assembly 112 rotates about the spindle bearing 128 in the direction in which the herring-bone pattern points. In a preferred embodiment, similar grooves are also provided on the upper annular surface 192 of the spindle bearing 128 . The grooves 304 described above may be substituted by vanes or other raised areas on the upper 192 and lower 196 annular surfaces of the spindle bearing 128 . As with grooves, the purpose of any such vanes or protrusions is to pump air to an intermediate or inner circumference of the upper 192 and lower 196 annular surfaces of the spindle bearing 128 , thereby increasing the stiffness of the air bearing 104 in a direction along the longitudinal axis 140 of the spindle 124 . In an alternative embodiment, the grooves illustrated in FIG. 3 may be provided on the upper annular surface 172 of the sleeve 148 , adjacent to the upper annular surface 192 of the spindle bearing 128 , and on the surface of the thrust plate 152 that is adjacent to the lower annular surface 196 of the spindle bearing 128 . Suitable groove designs are similar to those used when the grooves are provided on the upper 192 and lower 196 annular surfaces of the spindle bearing 128 , however, the direction of such grooves would be reversed. Therefore, for example, when a herring-bone pattern is used, the herring-bone elements will point in a direction opposite that of the rotation of the sleeve 148 with respect to the spindle bearing 128 of the base assembly 108 . Also, the grooves may be replaced by vanes or protrusions which serve the purpose of pumping air to an intermediate circumference of the upper 184 and lower 188 annular spaces. A detail of one of the thrust bearing grooves 304 is shown in FIG. 4 . As can be seen from that figure, each thrust bearing groove 304 is generally comprised of two arcuate grooves joined at their ends to form one larger groove generally having an arrow-head shape. Radii 404 of the annular surfaces 192 and 196 of the spindle bearing 128 are shown in FIG. 4 for illustration purposes. The radii 404 emanate from the longitudinal axis 140 (or center line) of the spindle 124 . The inner groove portion 408 of the thrust bearing groove 304 can be seen to intersect each radius 404 at an angle a 412 . According to the illustrated embodiment, the angle a 412 is equal at any point along inner groove portion 408 through which a radius 404 of the annular surfaces 192 and 196 of the spindle bearing 128 is drawn. The upper groove portion 416 is also shown with radii 404 of the spindle bearing 128 passing through it for illustration purposes. The angle β 420 between the upper groove portion 416 at the radii 404 is, according to the illustrated embodiment of the invention, the same, regardless of the point along upper groove portion 416 that a radius 404 of the annular surfaces 192 and 196 of the spindle bearing 128 is drawn. Furthermore, in a preferred embodiment of the present invention, the angles α 412 and β 420 are equal. Most preferably, the angles α 412 and β 420 are in a range of from about 20° to about 30°. Although the grooves 204 and 304 or vanes used to draw air to intermediate or inner portions of the bearing surfaces may be positioned on either the spindle bearing 128 or the bearing surfaces of the hub assembly 112 (i.e. the sleeve 148 and the thrust plate 152 ), they generally should not be placed on both the spindle bearing 128 and the bearing surfaces of the hub assembly 112 . If grooves are provided on opposing surfaces, air pressure is not developed properly. In a preferred embodiment, the length of the spindle bearing 128 is about 8 mm, the diameter of the spindle bearing 128 is about 20 mm, and the inside diameter of the sleeve 148 is about 21.5 mm. The spindle 124 has a diameter of about 5 mm. The radial clearance between the upper annular surface 192 of the spindle bearing 128 and the upper annular surface 172 of the sleeve 148 , and between the lower annular surface 196 of the spindle bearing 128 and the thrust plate 152 , is about 9.0 μm. The hub 144 extends vertically from the flange 164 for about 12 mm, and has an outer diameter of about 25 mm over that distance to allow the hub to accept a stack of magnetic storage disks. The inside diameter of the hub 144 between about the flange 164 and the clamp 168 has a diameter of about 23.5 mm and defines an upper inner cylindrical volume. The sleeve 148 fitted within this upper inner cylindrical volume has an inside diameter of about 21.5 mm. In FIG. 5, an air bearing having an inside-out underslung motor design constructed in accordance with another embodiment of the present invention is identified as air bearing 504 . In general terms, the air bearing 504 differs from the embodiment of the present invention illustrated in FIG. 1 in that the bearing area of air bearing 504 is increased. This is because, for a given height of the hub 544 in FIG. 5, as measured from the clamp 564 to the flange 560 , the spindle bearing 528 and the sleeve 548 are about 60% longer than those in the air bearing 104 shown in FIG. 1 having a hub 144 with an equal height, as measured from the clamp 168 to the flange 164 . This increased bearing size is the result of the inside-out underslung motor design of the air bearing 504 , which offers increased radial bearing stiffness over the embodiment of FIG. 1, while maintaining a compact overall size. Indeed, in a preferred embodiment, for a given disk drive size format, the external dimensions of air bearing 504 are no larger than the external dimensions of air bearing 104 . The air bearing 504 is generally comprised of a base assembly 508 and a hub assembly 512 . The base assembly 508 of the present embodiment is similar to the base assembly 108 of the embodiment illustrated in FIG. 1 in that it generally comprises a base 516 , only a portion of which is illustrated in FIG. 5, a stator assembly 520 , and a spindle 524 . The spindle 524 includes an enlarged bearing portion 528 . The stator assembly 520 is comprised of laminations 532 and coils 536 . The laminations 532 are affixed to the base 516 and are arranged radially about the longitudinal axis 540 of the spindle 524 . Being a part of the base assembly 508 , the spindle 524 is affixed to the base portion 516 . The coils 536 of the stator assembly 520 are disposed about the laminations 532 . In a preferred embodiment, the laminations 532 comprise thin sheets of a ferromagnetic material stacked on top of one another, and the coils 536 comprise an electrically conductive wire having an insulating exterior, wound about the laminations 532 . Also in a preferred embodiment, the base 516 comprises cast aluminum, and the spindle 524 comprises machined steel. The hub assembly 512 comprises the hub 544 , sleeve 548 , thrust plate 552 , and magnets 556 . The hub 544 has an internal cavity that is substantially filled by the bearing portion 528 of the spindle 524 . The sleeve 548 according to this embodiment of the present invention extends beyond the lower extreme of the hub 544 . At the lower extreme of the hub 544 is a flange 560 onto which magnetic storage disks (not shown) may be stacked. The hub 544 also features a clamp 564 to which a retainer (not shown) may be affixed to retain the magnetic disks (not shown). The internal cavity of the hub 544 is generally cylindrical in shape. Affixed to this internal cavity of the hub 544 is the sleeve 548 . The interior of the sleeve 548 has an annular upper surface 568 and a cylindrical side surface 572 . The interior of the sleeve 548 is sized such that the inner diameter of the cylindrical side surface 572 is slightly larger than the diameter of the spindle bearing 528 . Thrust plate 552 has an annular shape, and is located adjacent to the lower annular surface 576 of the spindle bearing 528 . The thrust plate 552 is affixed to the lower portion of the sleeve 548 . The cylindrical side surface 572 of the sleeve 548 is slightly longer than the length of the spindle bearing 528 . Therefore, when the thrust plate 552 is affixed to the sleeve 548 , there is a thin upper annular space 580 and a similarly dimensioned lower annular space 584 between the spindle bearing 528 and the interior bearing surfaces 568 , 572 and 552 of the hub assembly 512 . A portion of the cylindrical side surface 572 of the sleeve 548 is adapted to receive a plurality of magnets 556 on its outer circumference. Accordingly, the magnets 556 are located radially about the longitudinal axis of the spindle 540 . Furthermore, the magnets 556 are positioned so that they are within a circumference described by the stator assembly 520 , and adjacent to the laminations 532 of the stator assembly 520 . Therefore, there is no need for a separate back iron component according to this embodiment of the present invention. In addition, the air bearing 504 having an inside-out underslung motor design features greater resistance to radial movement caused by magnetic forces than does the air bearing 104 having an underslung motor of conventional design. This is so because the air bearing 504 has a spindle bearing 528 that extends to at least the center line of the magnets 556 that interact with the stator assembly 520 when the hub assembly 512 is being rotated relative to the base 516 . The motor 588 of this embodiment of the present invention is generally comprised of the laminations 532 , the coils 536 , and the magnets 556 . When the motor 588 is in operation, an electrical current is supplied to the coils 536 , which creates a magnetic field about and through the laminations 532 . This magnetic force causes the hub assembly 512 to rotate relative to the base 516 through its interaction with the magnetic force of the magnets 556 . The rotation of the hub assembly 512 and the associated sleeve 548 and thrust plate 552 , relative to the spindle bearing 528 of the hub assembly 508 , creates a flow of air in the upper annular space 580 , the lower annular space 584 , and the cylindrical space 592 formed between the spindle bearing 528 and the side surface 572 of the sleeve 548 . This air flow creates higher air pressures in the spaces between the spindle bearing 528 , and the sleeve 548 and thrust plate 552 of the hub assembly 512 . This high pressure air then serves to prevent direct contact between the spindle bearing 528 and the bearing surfaces of the hub assembly 512 . Because of the greater spindle bearing 528 length of the air bearing 504 having an inside-out underslung motor design, the radial stiffness (i.e. the resistance of the bearing to forces along a radius of the hub 512 ) of the air bearing 504 assembly is increased. Thus, the embodiment of FIG. 5 offers greater resistance to radial forces, and/or allows lower bearing tolerances while achieving acceptable amounts of bearing stiffness. In a preferred embodiment, the air bearing 504 has grooves on the upper 580 and lower 576 annular surfaces, and on the cylindrical side surface 572 of the sleeve 548 . The general design and arrangement of these grooves may be as discussed above with respect to the air bearing 104 having an underslung motor design. Also, the air bearing 504 may similarly utilize vanes rather than grooves in the bearing surfaces, and the vanes or grooves may be provided on the interior surfaces of the thrust plate 552 and sleeve 548 rather than on the spindle bearing 528 . In a preferred embodiment, the length of the spindle bearing 528 is about 13.5 mm, the diameter of the spindle bearing 528 is about 20 mm, and the inside diameter of the sleeve 548 is about 21.5 mm. The spindle 524 has a diameter of about 5.0 mm. The radial clearance between the lower annular surface 576 and the thrust plate 552 , and between the upper annular surface 580 and the upper surface of the sleeve 568 is about 9.0μm. The upper portion of the hub 544 defines an inner cylindrical volume having a diameter of about 23.5 mm. The sleeve 548 fitted in this inner cylindrical volume has an inside diameter of about 21.5 mm. The foregoing discussion of the invention has been presented for purposes of illustration and description. Further, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, within the skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain the best mode presently known of practicing the invention and to enable others skilled in the art to utilize the invention in such or in other embodiments and with various modifications required by their particular application or use of the invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.	A disk drive spindle air bearing is disclosed having increased bearing stiffness, while being capable of manufacture using conventional tolerances. The invention therefore allows the construction of a disk drive spindle bearing without the need for oil or grease that may potentially contaminate the storage disks. The disclosed disk drive spindle air bearing also provides an air bearing having low acoustical noise and power consumption characteristics.	5
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophone with automatic inhibition when the immersion depth exceeds a certain adjustable threshold. 2. Description of the Prior Art It is well-known to form hydrophones by assembling elements sensitive to pressure variations, such as discs made of a piezoelectric material, associated each with a pair of electrodes arranged on either side. Each disc is stuck onto a flexible support such as a diaphragm, one of the faces thereof being exposed to the pressure variations to be measured. The flexible support has for example the shape of a cup which can be supported by a rigid housing or which can rest against an identical cup, itself carrying one or more sensitive elements, the two cups being in contact with one another at one edge and delimiting a housing. The electrodes of the two sensitive elements are preferably electrically interconnected so as to provide compensation for the parasitic effects due to accelerations. When the outside static pressure increases, the two plates bend until they rest against each other. The space between them is so selected that their maximum deformation, when they are pressed against each other, remains within elastic deformation limits. The detector is thus protected against accidental overpressures. The housing thus formed can be coated with a layer made of a material transparent to acoustic waves. The sensitive elements can be externally fastened to the housing so that their sensitivity does not vary much with the hydrostatic pressure variations (less than 10% for a 10 Map static pressure for example). The sensitive elements are generally covered with a protecting coating (such as a varnished araldite layer) so as to maintain a sufficient electric insulation in relation to the outside environment. This layout allows obtaining of very sensitive detectors at a relatively low cost. According to another well-known layout, the sensitive elements are fastened to the inner faces of the cups and therefore inside the housing, which provides good protection against the outside environment. A stop can be arranged between the two cups so as to limit deformation of the diaphragms towards the inside and to short-circuit the electrodes of the two sensitive elements facing each other. It is also well known to position the housings containing one or two sensitive elements inside a rigid tube by means of a hollowed flat centering element made of a deformable material, and to run an acoustically transparent sealed sheath therein. In subsea seismic listening applications or for seismic prospecting, these tubes are distributed in large numbers inside a supple sheath of often very great length, or streamer, filled with kerosine or mineral oil, which is towed by a boat Various piezoelectric detectors are described for example in French patents 1,556,971, 2,122,675, 2,748,183 or 2,792,802 or U.S. Pat. No. 5,889,731, all filed in the name of one of the applicants or of both, or in U.S. Pat. Nos. 3,970,878, 4,336,639, 4,926,397 or 5,136,549. Piezoelectric hydrophones, such as those mentioned above, are designed to work within a certain depth range. The sensitivity of the piezoelectric elements decreases with the flexion of the diaphragms. Beyond a certain flexion, their response to the pressure variations to be measured stops being reliable, and it can even become zero in case of a short-circuit of the electrodes facing each other (detectors with sensitive elements against the inner faces of the cups). SUMMARY OF THE INVENTION The automatic-inhibition hydrophone according to the invention is suited for use in a well-defined and adjustable depth range and is automatically inhibited when a predetermined depth threshold is exceeded. The hydrophone of the invention comprises at least one detection unit producing an electric signal on electric wires in response to the pressure variations applied. The hydrophone of the invention comprises at least one flexible diaphragm that bends under the action of the pressure exerted externally on the hydrophone and a switch arranged opposite so as to be actuated by the diaphragm for a predetermined outside pressure, at least one of the electrical wires of the detection unit being connected to the switch so that the release of the switch inhibits the response of the sensitive element. According to a first embodiment, the hydrophone comprises a tubular body comprising a fist chamber closed by a flexible diaphragm which bends under the action of the pressure exerted externally on the hydrophone, and a second chamber open onto the outside environment and communicating with the first chamber by a channel. The switch has a push element which is arranged opposite the flexible diaphragm closing the first chamber so as to be actuated thereby for a predetermined outside pressure, the detection unit is arranged in the second chamber, so that at least one of the electrical wires is connected to the switch in the first chamber, so that release of the switch by action of the flexible diaphragm inhibits the response of the sensitive element. The hydrophone comprises for example a block made of an acoustically transparent material in which the detection clement of the second chamber is embedded. According to a first variant, the second chamber is separated from the first chamber by an inner partition including at least one channel allowing passage of at least one electrical wire connecting the switch to the detection unit, and the inner wall of the body on the first chamber side is, for example, designed to limit deformation of the diaphragm towards the inside of the first chamber. According to another variant, the second chamber is separated from the first chamber by an inserted rigid plate made of a dielectric material which is fastened to the inside of the body, this plate carrying the switch and being suited to bring it into electrical contact with at least one electrical wire connecting the switch to the detection unit. This rigid plate is, for example, an insulating plate provided with conducting tracks allowing connection of the terminals of the switch to the electric wires of the detection unit. The hydrophone comprises, for example, a ring made of a plastic or metallic material, arranged in the first chamber between the diaphragm and the rigid plate, which is suited to limit deformation of the diaphragm towards the inside of the first chamber. According to a first embodiment example, the detection element in the second chamber comprises a housing of two cups resting against each other, at least one of the cups being provided with a flexible central part or diaphragm, and at least one sensitive element associated with electrodes, which is fastened to the central part of at least one of the cups, electric conductors connected to the electrodes of each sensitive element, and a protective sheath for protection of the detection unit, the switch being connected to at least one electrical conductor. According to a second embodiment example, the detection element in the second chamber comprises a housing of two cups resting against each other, at least one of the cups being provided with a flexible central part or diaphragm, and at least one sensitive element associated with electrodes, which is fastened to the central part of at least one of the cups, electrical conductors connected to the electrodes of each sensitive element, and a protective sheath for protection of the detection unit, the switch connected to at least one electric conductor being arranged inside the housing so as to be released by at least one diaphragm of the housing bending under the action of the hydrostatic pressure. According to another example, the detection element comprises an intermediate support arranged between the two cups, the switch being fastened to this intermediate support with a push element thereof facing the central part of one of the cups, and a sealed insulating bushing for passage, towards the outside of the housing, of an electric conductor connected to the switch. According to another embodiment example, the switch is of the type provided with flexible blades suited to remain in electric contact with one another as long as the flexion of at least one of the diaphragms remains below a fixed threshold. According to another embodiment, the tubular body of the hydrop hone comprises a fixed part containing the detection unit and the switch, and a moving part closed at a first end by the diaphragm, tightly screwed onto the fixed part, so that the effective space remaining between the diaphragm and the push element allows the switch to be always released at a well-defined pressure. The hydrophone is therefore preferably mounted in such a way that the moving part of the body is first fitted onto the fixed part by screwing, a predetermined nominal pressure applied to the diaphragm causing bending thereof towards the inside of the body, then fitting of the two parts onto each other by continued screwing until the switch is actuated by the bent diaphragm. As the case may be, the switch is normally open or normally closed. The hydrophone, as defined above, is light and compact. Its outer surface is practically free of rough patches likely to disturb fluid flows around the outer surface. The diaphragm provides perfect sealing and insulates the switch electrically. Furthermore, the embodiment and the mounting mode wherein the body is made of two parts that fit into one another allows obtaining a good reproducibility of the hydrophone triggering conditions. BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the hydrophone according to the invention will be clear from reading the description hereafter of non limitative examples, with reference to the accompanying drawings wherein: FIG. 1 diagrammatically shows a first embodiment of the hydrophone with its switch allowing controlled inhibition when a fixed depth value is exceeded, FIG. 2 diagrammatically shows an embodiment of the detection element of the hydrophone, FIG. 3 diagrammatically shows a protective sheath for the detection element, FIG. 4 diagrammatically shows the detection element of FIG. 3 in its tubular housing, FIG. 5 diagrammatically shows a second embodiment of the detection element with an internal switch, FIG. 6 diagrammatically shows a third embodiment of the detection element with an internal switch provided with flexible blades, FIGS. 7 and 8 diagrammatically show two embodiment variants of the hydrophone of FIG. 1 comprising inserted elements inside the body of the hydrophone and two different switches, FIG. 9 diagrammatically shows an improved embodiment allowing obtaining of precise adjustment of the hydrophone triggering threshold, and FIG. 10 diagrammatically shows a hydrophone mounting tool allowing obtaining of fine adjustment of the hydrophone triggering threshold. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hydrophone comprises (FIGS. 1 and 4) a tubular body 1 open at both ends. A partition 2 divides the inside of body 1 into two unequal chambers 1 a and 1 b which communicate with one another through a relatively narrow channel 3 . The end of body 1 , on the small chamber 1 a side, is closed by a diaphragm 4 made for example from a Cu/Be alloy. The terminal part of body 1 is bevelled towards the inside. The small bowl 5 defined by this bevel allows diaphragm 4 to bend towards the inside of body 1 . A switch 6 provided with a push element 7 , on which diaphragm 4 can push and actuate by bending, is fastened (by adhesion for example) to the center of small chamber 1 a . Switch 6 can be normally open or normally closed, as the case may be. A pressure-sensitive reception unit S is arranged in the larger chamber 1 b . The unit S is embedded in a block made of an acoustically transparent plastic material 8 which insulates it from the outside environment. The signal produced by reception unit S in response to the pressure variations of the outside environment is available on electrical conductors 9 a and 9 b . Switch 6 is interposed on at least one of the conductors so that its release inhibits the signal of reception unit S. If switch 6 is normally closed, for example (FIG. 1 ), it is interposed on one of the wires 9 a so that its release opens the circuit. The flexibility of diaphragm 4 and the position of push element 7 are so selected that switch 6 is actuated and the hydrophone is cut off for a predetermined hydrostatic pressure, 3 MPa for example. It has been observed that the hydrostatic triggering pressure remains particularly stable and practically insensitive to aging. Reception unit S can be of any type, with for example having a sensitive element of a tube or a hollow sphere made of a piezoelectric ceramic associated with electrodes. The pressure variations are transmitted thereto creating mechanical stresses that the sensitive element translates into an electric signal. In the embodiment described hereafter by way of example, the flexion of the diaphragms is used to generate stresses in one or more piezoelectric ceramic discs. Each reception unit S comprises (FIG. 2) a housing 10 having two identical cups 10 a and 10 b arranged symmetrically, resting against each other on the periphery thereof, provided for example with a resting edge or rim 11 . The cups can be machined or drawn. A sensitive element 12 , such as a piezoelectric ceramic disc for example associated with two electrodes 12 a and 12 b , adheres to the face of the flexible central part of each cup 10 a and 10 b . Electrode 12 b of each sensitive element is for example a conducting film interposed between sensitive disc 5 and the resting face of cup 10 a and 10 b , or possibly this face itself, if electrode 12 b is electrically conducting. Preferably, according to a conventional connection mode, electrodes 12 a and 12 b of the two sensitive elements 12 are respectively interconnected. When housing 10 is electrically conducting (as it is the case in the embodiment described), it is this housing which provides interconnection of electrodes 12 b in contact with cups 10 a and 10 b . The opposite electrodes 12 a are interconnected by connection of associated conductors 13 a A conducting wire 13 b is electrically connected to housing 10 . The voltage generated by the sensitive elements in response to the pressures applied outside the housing is available between wires 13 a and 13 b . Housing 10 is inserted in protective sheath 14 made of an insulating plastic material. Reception unit 1 in its sheath 14 is in a median plane of the larger chamber 1 b (FIG. 4) and embedded in a block of controlled thickness. According to the embodiment of FIG. 5, the hydrophone comprises a reception unit 1 as shown in FIG. 2, directly associated with a switch 15 arranged inside housing 2 . The switch is fastened to an intermediate support 17 arranged between cups 10 a and 10 b . The switch is normally closed and its terminals are interposed on electric conductor 13 b connected to the housing. This conductor 13 b runs through the wall of housing 10 by means of an insulating sealed bushing 18 (glass bead for example). The voltage V delivered by the hydrophone is available between interconnected conducting wires 13 a and common wire 13 b . Again, in this case, the height of cups 10 a and 10 b and their flexibility are selected according to the dimensions of switch 15 so that push element 16 is actuated for a well-defined boundary hydrostatic pressure, and the hydrophone is disconnected. According to the embodiment of FIG. 6, switch 6 is of the type provided with flexible blades with a first blade 19 electrically connected to one of the cups 10 a and a second blade 20 electrically insulated from housing 10 by a glass bead 16 . Blades 19 and 20 are designed to remain in contact with one another as long as the flexion of at least one of the diaphragms under the action of the outside pressure remains within fixed limits. The absence of contact brings, for example, one of the terminals of the hydrophone into the air. In the embodiment of the hydrophone shown in FIGS. 7 and 8, the elements corresponding to those of FIGS. 1 and 4 have the same reference numbers. The hydrophone also comprises a tubular body 1 with one end closed by a diaphragm 4 made of for example a Cu/Be alloy. A ring 21 made of a plastic material such as nylon and bevelled towards the inside is pressed against diaphragm 4 . The small bowl 5 defined by this bevel allows flexion of diaphragm 4 towards the inside of body 1 . The partition, which separates chambers 1 a and 1 b , is an inserted rigid plate 22 made of a non-conducting material. Switch 6 is provided with a push element 7 fastened to one of the faces, on the small chamber 1 a side. By means of conducting tracks running through plate 22 , the terminals of switch 6 are electrically connected to electrical conductors 9 a and 9 b associated with transducer S. Mounting of the hydrophone is thus simplified. Ring 21 is first fitted into body 1 at the open end thereof until it is in contact with the diaphragm and it is fastened to the inner wall of the body, by adhesion for example. Rigid plate 22 is then engaged until the push element is in contact with the diaphragm and the push element is similarly fastened by adhesion so as to tightly separate the two chambers. Transducer S, which is electrically connected to at least one of the conducting wires connected through rigid plate 22 to the terminals of switch 6 , is then placed in the body and is insulated from the outside environment by filling large cavity 1 b with an acoustically transparent material 8 . Similarly, switch 6 can be normally open or normally closed. According to the embodiment of FIG. 9, which is a variant of the previous embodiment of FIG. 7, body 23 of the hydrophone comprises a part 23 a containing reception unit S and associated elements 6 , 7 and 22 , and a complementary part 23 b forming a cover which can be assembled by screwing onto part 23 a . The inner wall of part 23 a comprises a shoulder 24 against which rigid plate 22 rests and an external thread 25 . Cover 23 b also comprises an inner shoulder on which the bevelled ring forming a stop 21 rests and an external thread suited to the external thread 25 of part 23 a of the body. Diaphragm 4 is welded (laser welding for example) onto the terminal face of cover 23 b . Orifices 26 are provided, preferably through the wall of the body, allowing discharge of the air that may have been trapped during mounting of the hydrophone. During the mounting operation, rigid plate 22 associated with reception unit S is fitted into part 23 a of the body until it rests against shoulder 24 and it is held in position by drawing. Cover 23 b is then screwed onto part 23 a so as to insulate chamber 1 a from the outside environment. Driving in of the cover by screwing is so adjusted that the hydrophone is inhibited for a predetermined pressure. A tubular part 27 (FIG. 10 ), whose inner section is suited to the outer section of cover 23 a and internally provided with a seal 28 , is therefore used. A channel allowing communication with a source delivering a fluid under an adjustable pressure, adjusted to the desired hydrophone inhibition pressure, is connected to part 27 . Tubular part 27 allows cover 23 b of the body to be tightly covered and the predetermined pressure is applied, which causes the diaphragm to bend towards the inside of the housing. By means of a tool, cover 23 b is then screwed onto part 23 a of the body until the bent diaphragm is pressed against push element 7 and releases switch 6 . This adjustment of each hydrophone is particularly simple, fast and convenient because it is suited to the mechanical elements used which cooperate to produce the release. It accounts for the effective flexibility of diaphragm 4 , of the effective dimensions of switch 6 , of the effective travel of push element 7 , considering the manufacturing tolerances of these elements, and obtains release at a constant nominal pressure. For applications to marine seismic prospecting, hydrophones such as those described above can for example be distributed at a distance from one another along a streamer suited to be towed immersed behind a towboat.	A hydrophone which is automatically inhibited when the immersion depth exceeds a predetermined threshold by action, on the push element ( 7 ) of a switch ( 6 ), of a flexible wall that bends under the action of the outside pressure. The hydrophone comprises a tubular body ( 1 ) with two chambers ( 1 a , 1 b ) separated by a partition ( 2 ). One of the chambers is closed by a flexible diaphragm ( 4 ). Switch ( 6 ) is fixed at the center of one of the chambers. Diaphragm ( 4 ) can push down on and actuate push element ( 7 ) by bending. The body can advantageously consist of two parts that can be screwed onto one another, which allows easier adjustment of the inhibition pressure. A pressure-sensitive reception unit (S) is arranged in the other chamber.	6
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the printers used in conjunction with personal computers. More specifically, it involves a way to make such a printer more versatile by providing it with the capability to accommodate more than one paper output medium at any given time. 2. Background Information Within the past decade, the personal computer industry has grown so quickly that these small computers have come to be considered almost an absolute necessity, rather than a luxury, for those operating small businesses, such as pharmacies, medical or dental practices, and the like. Through the use of such computers, and appropriately designed software, businessmen are able to maintain their accounts, budgets and inventories in a form that can be readily accessible, easy to manage, and much less prone to the problems that can befall paper files. It is easy with this technology to maintain lists of current or prospective customers and suppliers on appropriate storage media. Often, drawing from such a list, a small businessman or other personal computer user has occasion to do a mass mailing as a way to conduct, for example, an advertising campaign. A general form letter to be sent to all in the target group is composed with spaces left in the appropriate places for insertion of addressee information. Then, the file of target addresses is accessed and a "personalized" letter to each in that group is printed out. When this job has been completed, the same file of target addressees must again be accessed in order that mailing labels can be printed. While this in itself is a simple matter, the troublesome, intermediate step of changing the output medium must first be performed. In a rather short time, the repeated changing of output media, in order to make full use of the personal computer's capabilities, becomes quite tiresome. Currently, the only alternative open to the personal computer user is to purchase a second printer and to dedicate it to the printing of mailing labels alone. Then, either by selecting the printer desired through a software command or by changing the position of an external switch, output would be directed to one printer or the other. While this option would allow one to avoid the repeated substitution of various paper media in a single printer, it calls for the additional investment in a second printer and associated connecting hardware. In addition, one loses the use of the additional desk or table space required by the second printer. These difficulties would be solved by the availability of a single printer having a carriage wide enough to accommodate more than one output media side-by-side at any given time. For example, with reference to the above discussion, a printer wide enough to handle both 80-column letter stationary and 35-column address labels would present a highly desirable option to a small businessman who wishes to make more efficient use of his personal computer and printer. SUMMARY OF THE INVENTION This invention is a device which incorporates two separate and independently driven means for transporting continuous paper media. Only one of the two means for transporting continuous paper media is operated at any given time as output from a personal computer is being printed on the paper media loaded therein. The device can either be built into a wide carriage printer of the kind commonly used with personal computers, or supplied as an accessory for such a printer. It is also possible, with appropriate design modification, to adapt it for use as an attachment on a typewriter as an accessory. In the present context, the term "tractor" refers to the mechanism which carries out the task of transporting the continuous paper. It does so by means of belts having regularly spaced pins which engage with equally spaced holes along the side edges of the continuous paper. The simultaneously driven belts pull or push the paper through the printer. The so-called twintractor of this invention, therefore, comprises two such tractors arranged in a side-by-side relationship with respect to each other on a single printer. It is contemplated that at any given time, only one of the tractors will actually be in use. However, with this invention, it will no longer be necessary to change paper media as is the case with a narrow 80-column printer, when one wishes to print address labels instead of letters, or vice versa. Instead, by appropriate means, power is delivered only to the tractor carrying the desired paper output medium. At the same time, the print head, which is the component actually printing the output character-by-character and line-by-line, is automatically aligned with the left-hand margin of the paper output medium chosen. These can be done either separately or simultaneously, either by mechanical or electromechanical means, or by an appropriate command from the computer keyboard. Each of the tractors further comprises both a paper sensor and a paper parking detector. The paper sensors are essentially means which determine whether paper is currently loaded in the tractor. If the command is given to direct output to a tractor then not loaded with paper, the printer will be automatically disabled and a warning to that effect given to the operator, either by the printer or through the personal computer. The paper parking detector carries out a different function. In most personal computer printers is included a platen, a rubber-covered roller like that in a typewriter, around which the paper is wrapped during the actual printing. The platen turns in sequential steps as lines of output are printed on the paper. As noted above, only one of the two tractors will actually be in use at any given time. However, the turning action of the platen will tend to pull the paper output medium in the tractor then not in use, because of frictional forces between the surface of the platen and the paper. This, in turn, will tend either to inhibit the free turning of the platen or to tear the paper not in use, especially at the points where the pins on the stationary tractor belts engage with the holes along the paper's side edges. The paper parking detector provides a way to solve this problem without completely unloading the unused paper from the tractor. This solution is as follows. Once the choice of paper output medium to be used has been made, the paper parking detector provides a means to withdraw the other paper output medium from around the platen. When the paper is withdrawn to the location of the paper parking detector, it sends out an appropriate signal to halt the withdrawal and "park" the paper at that point. The paper parking detector can be located, for example, with the paper sensor in the tractor. When the choice of printing on the "parked" paper output medium is made, the other medium is withdrawn, as above, and then the chosen medium is advanced automatically into the printer, around the platen, until the top line of the form aligns with the print head. Stated somewhat differently, the paper parking detector ensures that the paper is advanced by an amount which corresponds to the paper path length between that detector and the point on the platen where printing is actually carried out. With a printer incorporating a twintractor, the user also has the alternative of being able to use the complete width of the printer for standard 136-column paper by sliding one of the tractors to one side of the printer and loading the other with the wider paper. This assumes, however, that the rods on which the tractors are mounted are long enough to allow for this. Alternatively, the rods themselves could be designed to come apart in the middle in order to permit the removal of the temporarily unused tractor. By means of this invention, therefore, the personal computer user is provided with a way to give his printer a much greater flexibility than that possessed by any of those currently available on the market. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts the twintractor of the present invention as it would appear when installed on a typical personal computer printer. FIG. 2 presents the appearance of the twintractor before installation on a personal computer printer. FIG. 3 is a section view taken along the line 3--3 and in the direction indicated in FIG. 1, showing the means whereby the tractors may be alternately driven. FIG. 4 is a section view taken along the line 4--4 and in the direction indicated in FIG. 3. FIG. 5 shows an alternate embodiment of the present invention, where the twintractor is built into a personal computer printer, rather than installed as an accessory. FIG. 6 shows an alternate embodiment of the twintractor, wherein the choice of tractor to be driven is carried out in a different manner, and the rods capable of coming apart to temporarily remove a tractor. FIG. 7 shows the paper sensor and paper parking detector incorporated into the right side of a tractor. DESCRIPTION OF THE PREFERRED EMBODIMENT In the description which follows, any reference to either orientation or direction is intended primarily for the purpose of illustration and is not intended in any way as a limitation of the scope of the present invention. With reference to FIG. 1, the twintractor of the present invention is shown installed as an accessory on a personal computer printer 2. As discussed above, the twintractor 1 is designed to transport in the alternative two separate paper output media. For the purpose of our present discussion, we shall assume that standard 80-column width letter stationery 3 has been loaded into the left-hand tractor of the twintractor 1 and mailing labels 4 have been loaded into the right-hand tractor. Both forms of paper output media are assumed to be in continuous form. In general, any two kinds of paper output media can be loaded simultaneously into the twintractor 1 provided that their combined width can be handled by the printer. Proceeding on to FIG. 2, a closer view of the twintractor 1, it can more clearly be seen that it can simultaneously be loaded with two paper output media, in this case, letter stationery 3 and mailing labels 4, each carried separately by its own independently driven tractor. Each tractor has a left side 5 and a right side 6. Both sides of each tractor include means comprising evenly spaced pins 7 which protrude through equally spaced holes 8 on the side edges of the paper output media. This engagement of pins 7 through holes 8 is the mechanism whereby the paper output media is driven. Defining the width of the twintractor 1 is a clamp rod 9. Suitably attached to the ends of the clamp rod 9 are a left end piece 10 and a right end piece 11. The left side 5 and the right side 6 of both tractors are slideably deployed on the clamp rod 9. All can be locked into fixed positions on the clamp rod 9 by clamping mechanisms 12. By the release of a clamping mechanism 12, the left side 5 or right side 6 of a tractor can be moved in order to accommodate paper output media of various widths. Two other rods, parallel to the clamp rod 9, extend across the width of the twintractor 1. For convenience, they are referred to as a top rod 13 and a bottom rod 14. For reasons to be explained below, these should not be of circular cross-section. The top rod 13, when turned by means of gear 15 at its extreme left end, drives the left side 5 and the right side 6 of the left-hand tractor, thereby transporting the letter stationery 3. The bottom rod 14, when turned by means of gear 16 at its extreme left end, drives the right-hand tractor in the same way, thereby transporting the mailing labels 4. It will be noted in FIG. 2 that the right side 6 of each tractor is supplied with an electrical connecting cable 17. This carries out two functions which will be discussed in connection with a later figure. Turning now to FIG. 3, one is given a section view of the twintractor 1 taken along the line 3--3 and in the direction indicated in FIG. 1. The cross-section of the right side 6 of the left-hand tractor will be first discussed. The pins 7, whose task is to actually move the paper output media, can be seen as evenly spaced projections on the outer surface of a belt 18. The inner surface of the belt 18 is characterized by evenly spaced teeth 19. Cross-sectional views of the clamp rod 9, the top rod 13, and the bottom rod 14 are also included. When the clamping mechanism 12, shown in FIG. 2, is released, there is sufficient clearance at points 20, 21, and 22 to enable the right side 6 of the left-hand tractor to slide along the clamp rod 9, top rod 13, and bottom rod 14. The left sides 5 and rights sides 6 of both tractors share all the characteristics mentioned in this paragraph. It should be recalled that the top rod 13 was said to drive the left-hand tractor, and the bottom rod 14 was said to do so for the right-hand tractor. The manner in which this can be accomplished is also illustrated in FIG. 3. It will be seen there that a gear 23 is deployed on top rod 13, and a wheel 24 is deployed on bottom rod 14. Gear 23 comprises teeth which mesh with the teeth 19 on the inside of the belt 18. By this means, when the top rod 13 is rotated by gear 15, gear 23 will move belt 18. The smooth surface of wheel 24 will ensure that the teeth 19 of belt 18 will encounter little resistance when sliding over that surface. By the same token, when bottom rod 14 is rotated by gear 16, the smooth surface of wheel 24 will not permit it to drive belt 18. The left side 5 and the right side 6 of the left-hand tractor both operate as described in the above paragraph and as illustrated in FIG. 3. That is, the rotation of top rod 13 drives the belts 18 on both left side 5 and right side 6 simultaneously, thereby transporting the paper output media 3 located there. The rotation of the bottom rod 14 has no effect upon the left-hand tractor. The left side 5 and the right side 6 of the right-hand tractor differ from what is shown in FIG. 3 in one important respect, that the positions of gear 23 and wheel 24 are reversed. That is, gear 23 is deployed on the bottom rod 14 and wheel 24 is deployed on the top rod 13. In this way, the rotation of the bottom rod 14 drives the belts 18 of the left side 5 and the right side 6 of the right-hand tractor simultaneously, thereby transporting the paper output media 4 located there. The rotation of top rod 13 has no effect upon the right-hand tractor because of the smooth surface of wheel 24. In either case, the non-circular cross-section of top rod 13 and bottom rod 14 will enable them to rotate gears 23 and wheels 24 even though there is clearance, as mentioned above, at points 20 and 22. In FIG. 3, a detailed view of the left end piece 10 of the twintractor 1 is presented. Gear 15 and gear 16 provide the means for rotating the top rod 13 and the bottom rod 14 respectively. Additional gears are depicted in order to indicate one way in which the top rod 13 and the bottom rod 14 can be driven in the alternative. Gear 25 can be moved slideably between two positions, where it drives in the alternative gear 16 or gear 26, which eventually drives gear 15. In the latter instance, to be more specific, gear 26 drives gear 46, which, in turn, drives gear 15. The change in position of gear 26 can be accomplished by any of a great number of means known to those skilled in the art. In FIG. 3, gear 25 is retained on end piece 10 by pin 50, which passes through slot 52 in end piece 10. Pin 50 acts as an axle for gear 25, which rotates thereabout. Gear 25 and pin 50 may be slid from one end of slot 52 to the other to engage, in the alternative, gear 16 or gear 26. Gear 25 may be moved between the two end positions of slot 52 by hand. Retaining clip 54, attached to pin 50, may be secured between two nubs 56, 58 to retain gear 25, in the position shown in FIG. 3, to drive gear 16. On the other hand, retaining clip 54 may be retained to the right of nub 58 in FIG. 3 to force pin 50 against the opposite end of slot 52, so that gear 25 may engage with gear 26. Gear 27 is designed to engage with a gear 40 in the personal computer printer 2 for which the twintractor 1 is intended as an accessory. More specifically, gear 27 engages with gear 40 at the extreme end of platen 28 when the twintractor 1 is installed in the printer 2. In this way, the twintractor 1 is operated in tandem with the platen 28 of the printer 2 and advances the paper the appropriate amount as the printer 2 provides output line-by-line. It will finally be observed in FIG. 3 that gear 27, driven by gear 40, drives gear 44, which, in turn, drives gear 25. In general, it will be obvious to those skilled in the art that the gear ratios must be chosen to ensure that the twintractor 1 will transport continuous paper media 3, 4 by an amount equivalent to one line whenever the rotation of platen 28 advances it by that amount. Proceeding on to FIG. 4, one can see a section view of the bottom rod 14 at the point and in the direction indicated in FIG. 3. This provides an alternate way to illustrate the feature that the smooth surface of wheel 24, when rotated by bottom rod 14, will not drive belt 18 because of the relative lack of friction between the teeth 19 and the smooth surface of the wheel 24. Similarly, when driven by the top rode 13, the teeth 19 of the belt 18 slide freely over the smooth surface of the wheel 24. FIG. 5 presents an alternative embodiment of the invention, where the twintractor 1 is incorporated within a personal computer printer 2 rather than being supplied as an accessory. Also shown is the platen 28, the print head 29, and the paper 30, which is transported through the printer 2 as indicated by the arrow. FIG. 6 shows a further alternate embodiment of the twintractor 1, wherein the choice of tractor to be driven is carried out in a slightly different manner. The left end piece 10 and the right end piece 11 of the twintractor 1 are again shown, as are the clamp rod 9, top rod 13, and bottom rod 14. The top rod 13 is rotated by gear 15 at its extreme left end; the bottom rod 14 is rotated by gear 16 at its extreme left end. In this embodiment, both the top 13 and the bottom rod 14, in addition to being able to rotate freely within holes through the left end piece 10 and the right end piece 11, are able to slide back and forth along their respective axes. As before, the left side 5 and right side 6 of each tractor have a sufficient degree of clearance with respect to the top rod 13 and the bottom rod 14 to permit this sliding motion as this enables them to be adjusted for different paper output media widths. The clamp bar 9 is fixedly deployed between the left end piece 10 and the right end piece 11 and provides the means whereby the sides of each tractor are kept in fixed relative positions. Note further that, as before, when top rod 13 is rotated, gear 23 drives the belts 18 on the left-hand tractor, while the smooth surface of wheel 24 prevents it from having a similar effect on the right-hand tractor. Similarly, when bottom rod 14 is rotated, gear 23 drives the belts 18 on the right-hand tractor, while the smooth surface of wheel 24 prevents it from having a similar effect on the left-hand tractor. At the extreme right end of each rod 13, 14 is a knob 39. Clamped between each said knob 39 and the right end piece 11 is a spring 31 which exerts a rightward biasing force on each rod 13, 14, tending to maintain or restore them to the positions shown in FIG. 6. In this embodiment, when one makes the choice to use the left-hand tractor, a biasing force acts on the top rod 13 in the direction indicated by arrow 32, sliding it leftward to a point where the teeth of gear 15 engage with those of drive gear 33. Except for rotation, drive gear 33 is stationary, and is operated by means represented by the labelled rectangle and similar in principle to that seen in FIG. 3. When one has finished with the left-hand tractor, the biasing force is removed and the spring 31 restores the top rod 13 to the position shown in FIG. 6. Similarly, when one makes the choice to use the right-hand tractor, a biasing force acts on the bottom rod 14 in the direction indicated by arrow 34, sliding it leftward to a point where the teeth of gear 16 engage with those of drive gear 33. When one has finished with the right-hand tractor, the biasing force is removed and the spring 31 restores the bottom rod 14 to the position shown in FIG. 6. In addition, FIG. 6 illustrates a way in which an unused tractor could be removed from the twintractor 1 in the event the user wishes to load wide paper into the printer. The clamp rod 9, top rod 13, and bottom rod 14, can each be supplied in sections which are joined at points 35. Using this feature, the rods 9, 13, and 14 could be separated and the unused tractor temporarily removed. This can be accomplished in any of a great number of ways known to those skilled in the art. FIG. 7 shows the right side 6 of either of the tractors on the twintractor 1. As illustrated, the cover 36 has been opened in order to show the structure directly thereunder. As noted before in connection with the discussion of FIG. 2, an electrical connecting cable 17 is supplied to each right side 6. In this way, connection is provided for the paper sensor 37 and the paper parking detector 38. Each of these can be electrical switches of the kind that can be easily depressed and closed by the presence of paper in the tractor. While the invention has been particularly shown and described with reference to these preferred embodiments thereto, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the appended claims.	The twintractor is a device designed to be incorporated into a wide carriage personal computer printer, or supplied as an accessory to such a printer or a typewriter, giving it the capability of transporting and printing upon, in the alternative, one of two continuous paper media. The availability of such a device will provide the users of personal computers or typewriters with the flexiblility to print jobs on more than one kind of paper output media without the repeated necessity of changing paper encountered in standard 80-column width printers or carriages. A means for changing the zero position or left margin for the print head when the choice of print media is made is also incorporated in the device, as well as paper sensors, paper parking detectors, and removable tractors.	1
FIELD OF THE INVENTION [0001] The present invention relates to an optical MEMS scanning micro-mirror comprising a movable scanning micro-mirror, a substrate covering a back face of said mirror and a transparent prism substantially covering the reflection side of the micro-mirror. The present invention also relates to a micro-projection system comprising such a micro-mirror, and a corresponding method for reducing speckle. BACKGROUND OF THE INVENTION [0002] Speckle is a phenomenon created with laser light sources, due to the fact that laser light is coherent. Parallels and synchronized wavefronts simultaneously hit the projection surface. When the light hits the surface, it creates constructive and destructive interference. The first category of interference induces an image deterioration that is often visible by human eye and/or by sensors. In addition to a loss of image quality, visual comfort of the viewer may also be affected. [0003] Several techniques are used in order to remove or reduce speckle. In many cases, light coherence reduction techniques are used. For instance, the light hitting the projection surface is provided from various projection angles. Polarized laser light hitting a depolarized film is also used. Otherwise, illumination using various laser wavelengths may also be used. [0004] Another approach consists in using vibration of the projection surface. The resulting systems are complex, expensive, and involve very specific hardware material. [0005] WO2009/077198 describes an optical system comprising a coherent light source and optical elements for directing light from the source to a target. The optical elements include at least one diffusing element arranged to reduce a coherence volume of light from the source and a variable optical property element. A control system controls the variable optical property element such that different speckle patterns are formed over time at the target with a temporal frequency greater than a temporal resolution of an illumination sensor or an eye of an observer so that speckle contrast ratio in the observed illumination is reduced. The variable optical property element may be a deformable mirror with a vibrating thin plate or film. This solution requires modifying the projection system in order to integrate additional components, such as diffusing elements. [0006] WO2007/112259 describes a system and method for reducing or eliminating speckle when using a coherent light source. A refracting device, comprising a birefringent material, is positioned such that the refracting device intercepts the coherent light. The refracting device rotates, thereby causing the ordinary and/or extraordinary beams to move. The human eye integrates the movement of the beams, reducing or eliminating laser speckle. The refracting device may include one or more optical devices formed of a birefringent material. Wave plates, such as a one-half wave plate, may be inserted between optical devices to cause specific patterns to be generated. Multiple optical devices having a different orientation of the horizontal component of the optical axis may also be used to generate other patterns. Furthermore, the refracting device may include an optical device having multiple sections of differing horizontal components of the optical axis. This solution involves a complex and expensive component, the rotating refracting device. Moreover, the integration of such device requires a specific global design. [0007] Optical MEMS (Micro-Electro Mechanical Systems) are moving structures that are adapted to deflect light over time and space. These structures are usually made of silicon and are operated using different actuation principles including magnetic, electrostatic, piezoelectric and/or thermal. [0008] Classically, MEMS mirrors are used in various optical applications and are usually delivered as stand-alone unprotected chips. When used in scanning applications for example, the incoming light is directly reflected on the mirror and usually does not transmit through any other material or media. [0009] However, an unprotected chip makes the mirror surface subject to optical and mechanical degradations due to dust or other material deposition. Fabrication of unpackaged mirrors may also reduce the fabrication yield of such device due to its sensitivity to external handling and tooling processes. Therefore a packaged MEMS mirror is strongly recommended to obtain high quality mirrors and a high fabrication yield. Among packaged MEMS mirror technologies, wafer-level packaging technology is the most suited for high volume high yield manufacturing. [0010] However when a mirror is protected, or encapsulated, with transparent or semi-transparent windows, if light is passing through the window, a light reflection will occur at both air-window interfaces. These reflections are usually considered as parasitic reflections. A standard way to reduce these reflections is the deposition of anti-reflective coatings on both sides of the window, enabling the reduction of the parasitic reflections down to approximately 0.1% of the incoming light intensity 300 ( FIG. 3 ) if the coating is designed for a single wavelength, and down to 0.3% to 0.4% if the coating is designed for a larger wavelength spectrum such as the entire visible light (430-670 nm). [0011] However, when using a high power light source, such values of parasitic reflection may result in a strong degradation of the reflected light homogeneity. Indeed, as an example, for a laser-based MEMS scanning mirror projection system with a resolution of 640×480 pixels, a parasitic reflection as low as 0.3%, for a coated air-window interface, it will result in a fix parasitic pixel-light spot with a light intensity 1000 times stronger than any other pixel on the projected image or video. [0012] A consequence of such parasitic reflection is that the user will experience a brighter fix light spot in the projection field, which is a clear showstopper for standard use of the device and for customer adoption of the device. [0013] U.S. Pat. No. 6,962,419 describes a package for micro-mirror elements having a window that is not parallel to the substrate upon which the micro-mirrors are formed. Such configuration enables the reflected light to be oriented outside from the projection zone. However, this arrangement does not reduce perceived speckle by a user. [0014] Thus, there is a need for a novel micro-projection system with reduced speckle having MEMS micro-mirrors and MEMS components in general, that do not present the above mentioned drawbacks, namely the complexity and costs problems caused by using specific configurations with additional components used only for speckle reduction. There is also a need for a system avoiding undesired parasitic reflection of the light on the protection window. SUMMARY OF THE INVENTION [0015] A general aim of the invention is therefore to provide an improved device and method for reducing or suppressing speckle in a laser micro-projection system and avoiding parasitic reflection of the light on the protection window. [0016] Another aim of the invention is the elimination of the parasitic effect of the light reflection by intermediate media, within an optical scanning or projection field. [0017] Still another aim of the invention is to provide such method and device for reducing or suppressing speckle, providing efficient performances at reasonable cost. [0018] Yet another aim of the invention is to provide such method and device for reducing or suppressing speckle, using components that can be fully integrated into a laser micro-projection device. [0019] These aims are achieved thanks to the optical MEMS scanning micro-mirror and to the micro-projection system defined in the claims. [0020] There is accordingly provided an optical MEMS scanning micro-mirror comprising: a movable scanning micro-mirror pivotally connected to a MEMS body substantially surrounding the lateral sides of the micro-mirror; a transparent prism substantially covering the reflection side of the micro-mirror; said prism having an outer face and an inner face, wherein said outer face is not parallel to said inner face, thereby providing a dual anti-speckle and anti-reflection effect, namely against parasitic light reflection. [0024] The prism is advantageously part of the MEMS packaging. Therefore, no additional component is required to improve anti-speckle performance. [0025] Such functionalized protection system for optical components includes protective transparent or semi-transparent window or prism, leading to a strong reduction of parasitic light reflection. [0026] In such an arrangement, the back face is opposite of reflection face or side. [0027] In an embodiment, the MEMS further comprises a substrate covering a back face of said mirror. [0028] In an advantageous embodiment, the prism outer face is non-parallel to the micro-mirror neutral plane N-N. [0029] In a variant, the anti-speckle prism has its inner face also non-parallel to the micro-mirror neutral plane N-N. [0030] In another variant, the anti-speckle prism is provided with a transparent cover having a substantially flat outer face. In other words, the outer face is parallel to the neutral plane N-N. In such a case, at least a portion of the cover inner face is preferably substantially parallel with the prism outer face. This enables a further variant, in which at least a portion of the prism outer face and the cover inner face are in direct contact, thus avoiding the presence of air between the faces. In a still further variant, the cover inner face is preferably substantially parallel with the micro-mirror neutral plane N-N. [0031] In a preferred embodiment, the scanning mirror pivoting angle and dimensions and the prism dimensions are linked together and determined so that the light emitted from the scanning mirror is oriented to pass through the prism. [0032] In a still further variant, the prism is provided with an absorbent surface to absorb parasitic light. [0033] The prism is advantageously provided with a triangular profile. [0034] The anti-speckle prism is advantageously manufactured using a transparent parallelepiped portion provided with a plurality of successive structures made of rectilinear segments and aligned on the outer face thereof. The successive structures are preferably substantially triangular. Such triangular structures may be made in a single or multiple structures made of plastic injection or made of molded thermoplastic. [0035] In a variant, the triangular shape structures are provided on both sides thereof. Gluing or bonding may be used to attach the components. In a variant, the triangular shape structures are made in a single or multiple structures made of plastic injection. In another variant, the triangular shape structures are made in a single or multiple structures made of molded thermoplastic, such as Poly Methyl Methacrylate (PMMA). In a still further variant, the triangular shape structures are made in a single or multiple structures made of melted glass in the specific shape in a mould. [0036] The invention also provides a micro-projection system for projecting light on a projection surface comprising: at least one coherent light source, and preferably a plurality of light sources with a beam combiner; optical elements, in the optical path between said coherent light source and said projection surface, an optical MEMS scanning micro-mirror as previously described. [0040] The prism configuration involves a thickness varying according to the position. Thus, several parallel light beams crossing the prism have different path lengths to go through. Therefore, the prism is specifically adapted to modify the phase between adjacent light beam, resulting in a reduced coherence, and reduced speckle effect. More preferably, this characteristic of the prism has no impact on other design features. For instance, the prism does not comprise any curved surface, does not modify the direction of the beams, and does not modify the alignment of the light beams crossing the prism. [0041] Such system avoids parasitic light reflection in the desired field of projection and provides an anti-speckle effect. [0042] In an advantageous variant, the prism is made of quarter-wave plate material, thus providing double functionality. [0043] Such a micro-projection system may comprise in addition to the micro-mirror and the light source(s), a quarter-wave plate, a beam splitter, beam combiner, etc. [0044] The invention further provides a method for reducing speckle in a micro-projection system adapted for projecting light on a projection surface, comprising: providing a light with at least one coherent light source; directing light from the light source to the projection surface; providing a scanning micro-mirror for deviating light from said light source so as to scan a projected image onto said projecting surface, said micro-mirror being provided with neutral axis N-N corresponding to a non pivoted position of said micro-mirror, covering the reflection side of the micro-mirror with a transparent prism, said prism having an outer face and an inner face, said outer face being not parallel to said inner face, thereby providing a dual anti-speckle and anti-reflection effect. [0049] The required time for the light beams to pass through the prism depends on the thickness of the crossing zone. Due to its specific profile involving unparallel faces, when parallel light beams cross at different positions of the prism, they have different path lengths to travel through. For instance, if the crossing time increases from left to right, the time difference, though extremely small, is sufficient to reduce the coherence of the emitted light and thereby reduce the perceived speckle by a viewer or a sensor, while not affecting image sharpness. [0050] In other words, the different parallel light beams have different path lengths for passing through the prism, requiring different durations. This reduces the constructive and destructive interferences when the beams reach the screen. BRIEF DESCRIPTION OF THE DRAWINGS [0051] The foregoing and other purposes, features, aspects and advantages of the invention will become apparent from the following detailed description of embodiments, given by way of illustration and not limitation with reference to the accompanying drawings, in which: [0052] FIG. 1 describes a movable micro-mirror; [0053] FIG. 2A and FIG. 2B describe respectively a protected micro-mirror and its cross section; [0054] FIG. 3 presents examples of incoming light reflections on different parts of a MEMS micro-mirror; [0055] FIG. 4A , presents a schematic representation of a 640×480 pixels image with a stronger pixel light spot in the projection field; [0056] FIG. 4B is a schematic representation of a projection or scanning system comprising a light source and a micro-mirror; [0057] FIGS. 5A and 5B show two packaging architectures of a micro-mirror provided with an anti-speckle transparent prism in accordance with the invention, the resulting light reflections and transmission principles; [0058] FIG. 6 presents another packaging architecture of a micro-mirror provided with an anti-speckle transparent prism in accordance with the invention; [0059] FIGS. 7A and 7B are schematic illustrations of an improved manufacturing process for an anti-speckle prism in accordance with the invention; [0060] FIG. 8 shows a packaged micro-mirror with a further example of a micro-mirror provided with an anti-speckle transparent prism in accordance with the invention. DETAILED DESCRIPTION OF THE INVENTION [0061] For clarity, as is generally the case in representation of microsystems, the various figures are not drawn to scale. [0062] The present invention is based on studies performed by the inventors into the origins of parasitic light reflection onto transparent or semi-transparent surfaces for scanning and projection purposes. [0063] The invention proposes to change the geometry of the protection window to avoid parasitic reflection, provide an anti-speckle effect, while keeping the assembly simplicity of such window with other components. [0064] FIG. 1 presents a typical rectangular MEMS moving micro-mirror 101 , anchored to a fix body 102 by two beams 103 , and deflected along its central axis. [0065] An example of known type packaged MEMS mirror is presented in FIG. 2A and FIG. 2B , where the MEMS mirror 101 is protected by transparent or semi-transparent surfaces 201 and 202 as the incoming light can either come from one side or from two sides of the mirror surfaces. [0066] FIG. 3 presents the parasitic reflection of an incoming light 300 at both air-window interfaces of the surface 202 , resulting in 301 and 302 parasitic light reflections, and the light reflection 303 generated by the mirror itself. If the mirror is not actuated, the resulting reflection 303 is parallel to 301 and 302 . When the mirror is actuated, the incoming light beam is deflected and generates a 304 reflected beam. The 304 deflected beam is a single line for a micro-mirror moving along a single rotation axis, and is a two-dimensional pattern if the micro-mirror is moving along two rotational axis. [0067] The encapsulated MEMS micro-mirror is composed of a cap part with an optical window 202 that allows the light to penetrate and reflects on the micro-mirror surface. The cap optical window is typically made of glass, Pyrex or borofloat material and has usually a flat surface. Micro-mirror surface can also be coated with reflective material such as gold, aluminum or silver, deposited in thin film, to obtain strong light reflection in the visible and Infra-Red wavelength. Eventually, the MEMS micro-mirror chip can also be packaged by a transparent or opaque substrate 201 from the other side of the MEMS micro-mirror chip. Ideally, each of the protection substrates made of transparent material should be coated on both sides with anti-reflective coating to avoid any parasitic light reflection. [0068] One aspect of the invention is to avoid that the parasitic light reflects directly onto the projection field in the case of a projection application. FIG. 4A shows a projected image 402 , with a resolution of 640×480 pixels, in which the parasitic light spot 401 is part of the projected image and is light intensity is much larger then the other image pixels 401 a. [0069] The invention proposes a system that allows redirecting the parasitic light spot 401 onto a region which is outside the projection field. FIG. 4B presents a projection or scanning module 404 using such method, where the light beam, coming from the source 400 , is reflected into the optical projection system chip 403 , resulting in a projection image 402 and a parasitic light reflection 401 outside the desired field of projection. [0070] Another aspect of the invention consists in reducing or suppressing speckle and therefore improves image quality. [0071] A further aspect of the invention is to place a highly absorbent surface 405 in the path of the parasitic light in order to absorb its energy. Dark surface for example will considerably limit reflections of the parasitic light in the system. [0072] The solution of the invention enables to deviate the parasitic incoming light source outside the projection field, while not degrading the projection image, and while reducing speckle. The proposed invention uses protection transparent or semi-transparent windows with a specific geometry. [0073] An aspect of the invention is presented in FIG. 5A where the transparent prism or window 500 allows the light to penetrate towards the mirror surface 101 . In this architecture the window has a substantially triangular shape that enables the incoming light 501 to reflect the parasitic light 502 created at the air-window interface outside the desired projection field 402 . Due to the proposed architecture, the parasitic light beam 502 is no longer parallel to the projection beam 503 when the micro-mirror is not actuated. Due to its substantially triangular profile, the required time for the light to pass through the prism 500 depends on the thickness of the crossing zone. For instance, in FIG. 5A , the crossing time increases from left to right. This is clearly seen when comparing the respective lengths of arrows 503 L which is shorter than arrow 503 R. The time difference, though extremely small, is sufficient to reduce the coherence of the emitted light and thereby reduce the perceived speckle by a viewer or a sensor, while not affecting image sharpness. [0074] An improvement of the invention is presented in FIG. 5B , where the transparent prism or window 507 is designed in such a way that not only the parasitic light reflection 502 at the air-window interface 504 but also the parasitic light reflection 505 at the window-air interface 506 , are redirected outside the projection field. In order to achieve such performance, the window 507 has a specific geometry where none of its two faces are parallel to the mirror neutral plane N-N. In order that the architecture depicted in FIG. 5B redirect the parasitic reflected light outside the projection field, the window angle should be larger than the absolute maximum deflection amplitude of the mirror. [0075] Another aspect of the invention is related to the assembly simplicity of a device with such a window, when assembled with other devices having a flat surface. Indeed, a convenient way to assemble different components together, and especially optical components, is when all the components have flat surfaces, ideally made of similar side dimensions. FIG. 6 presents another aspect of the invention where the window has a specific shape 600 in order to provide at least two supports, outside the beam stream, thus providing a surface adapted for assembly with other component 601 having flat surface. With this architecture, oblique windows surfaces can be parallel or not, but the window angle should be larger than the absolute maximum deflection amplitude of the mirror. [0076] All of these architectures presented in FIGS. 5A , 5 B and 6 can be done using different techniques, including plastic injection, PMMA molding or glass molding. Glass molding technique uses a pattern where the glass is melted. A further improvement of the invention in order to simplify the manufacturing of such a structure is to use a standard flat window surface 700 , 703 and glue or attach to it the patterned structure 701 , 702 , 704 and 705 , as presented in FIGS. 7A and 7B . Ideally these structures will have similar refractive index as the windows 700 , 703 and ideally the attached technique is by using glue with also similar refractive index. [0077] Still another aspect of the invention is to make the plate 601 with a geometry enabling this component to adapt to the shape of the window 600 , in such way that there is no air-space between the two layers, such as presented in FIG. 8 . [0078] Another improvement of the invention is to have the protected window or prism directly made of quarter-wave plate material. Indeed such system decreases the number of components of the projection system and minimizes the light energy loss as the number of air-material interfaces is reduces. Standard quarter-wave plates are usually made of quartz material that can be shaped in the desired architecture such as the ones presented in FIGS. 5B and 6 , to replace respectively 507 and 600 components. [0079] As micro-mirrors can be packaged on both sides of the chip, for the applications requiring that the light is applied from both sides of the mirror, the present invention and architecture is also adapted by attaching described window geometries on each side. [0080] In another variant, the prism and/or window is substantially parallelepiped with a gradient of refractive index from one side to the other, thus resulting in a similar phase difference of parallel light beams passing through the prism or window. Such an embodiment may be used with an additional transparent element adequately positioned to avoid parasitic reflection of the light on the protection window. [0081] The prism may be attached to the micro-mirror chip using any techniques, including but not limited to gluing, glass frit bonding, anodic bonding, eutectic bonding, molecular bonding, fusion bonding, low temperature direct bonding, soft soldering, metal thermo compression bonding, bonding with reactive multilayers, laser bonding, polymer attach, etc.	Optical MEMS scanning micro-mirror comprising:—a movable scanning micro-mirror ( 101 ) pivotally connected to a MEMS body ( 102 ) substantially surrounding the lateral sides of the micro-mirror;—an transparent prism ( 500, 600 ) substantially covering the reflection side of the micro-mirror;—wherein said prism has its outer face non-parallel to the micro-mirror neutral plane N-N, thereby providing a dual anti-speckle and anti-reflection effect, namely against parasitic light. The invention also provides the corresponding micro-projection system and method for reducing speckle.	6
FIELD OF THE INVENTION This invention relates generally to the field of downhole pumping systems, and more particularly to gas separators for separating gas from well fluid prior to pumping. BACKGROUND Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, a submersible pumping system includes a number of components, including an electric motor coupled to one or more pump assemblies. Production tubing is connected to the pump assemblies to deliver the petroleum fluids from a production stream in the subterranean reservoir to a storage facility on the surface. Production streams usually contain a combination of liquids and gases, and excessive amounts of gases in the production stream can cause the pump to malfunction or operate inefficiently. In progressive cavity pumps, gas pockets occupy space in the pump that could otherwise be occupied by desirable liquids, thereby lowering the efficiency of the pump. Most pumps work best with a gas concentration in the production stream of less than twenty five percent. Rotary gas separators have been used to remove gas from production streams before entry into the pump. Rotary gas separators take advantage of the difference in specific gravities of gas and liquids by using centrifugal force to separate the gas and liquid components. Rotary mechanisms such as spinning chambers force the liquids to the outside radius of the rotary separator and the gases remain near the inside radius of the rotary separator because liquids are heavier than gases. The radial positions of the liquids and gases after centrifugal separation are disadvantageously located for the desired venting of the gases to the wellbore and the axial pumping of the liquids. To solve this problem, rotary separators often employ crossover mechanisms that transfer the liquids to the center of the separator for entry into the pump and transfer the gases to the outer radius of the separator for venting away from the pump. These mechanisms include passages that route the gases and liquids to the desired location for venting into the wellbore or for pumping to the surface. The rotary and crossover mechanisms add complexity and cost to the separators, and can result in costly downtime for the submersible pumping system when repairs are needed. It would therefore be desirable to separate liquids and gases in a production stream without the use of complex mechanisms that increase manufacturing and maintenance costs. It is to these and other deficiencies in the prior art that the present invention is directed. SUMMARY OF THE INVENTION In a preferred embodiment, the present invention provides a submersible pumping system for producing a fluid from a wellbore. The submersible pumping system includes a pump, a motor that drives the pump and a separator assembly. The separator assembly is for separating gas from the fluid and includes an intake and a vent above the intake. Fluid enters the separator assembly at the intake and the vent returns a portion of the fluid into the wellbore for recirculation into the intake. In alternate preferred embodiments, the separator assembly includes a shaft rotated by the motor, an inducer rotated by the shaft, and an orifice positioned between the vent and the pump. The present invention provides a method for separating gas from a wellbore fluid. The method includes moving the wellbore fluid from an intake through a separator assembly, diverting a portion of the wellbore fluid from the separator assembly into the wellbore, and recirculating the diverted wellbore fluid into the intake. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of an electric submersible pumping system disposed in a wellbore constructed in accordance with a preferred embodiment of the present invention. FIG. 2 is an elevational view of a separator assembly for use with the electrical submersible pumping system FIG. 1 . FIG. 3 is a cross section view of the separator assembly of FIG. 2 . FIG. 4 is a top plan view of a support bearing for use with the separator assembly of FIG. 2 . FIG. 5 is a top plan view of a support bearing for use with the separator assembly of FIG. 2 FIG. 6 is a top view of an orifice plate for use with the separator of FIG. 2 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with a preferred embodiment of the present invention, FIG. 1 shows an elevational view of a pumping system 100 attached to production tubing 102 . The pumping system 100 and production tubing 102 are disposed in a wellbore 104 , which is drilled for the production of a fluid such as water or petroleum. As used herein, the term “petroleum” refers broadly to all mineral hydrocarbons, such as crude oil, gas and combinations of oil and gas. Petroleum enters the wellbore 104 through perforations 105 . The production tubing 102 connects the pumping system 100 to a wellhead 106 located on the surface. Although the pumping system 100 is primarily designed to pump petroleum products, it will be understood that the present invention can also be used to move substances that consist of other fluids. The pumping system 100 preferably includes some combination of a pump assembly 108 , a motor assembly 110 and a separator assembly 112 . Although not shown, the pumping system 100 can also include components such as seal sections, gear boxes and various sensors. The motor assembly 110 is provided with power from the surface by a power cable 114 . The motor assembly 110 preferably drives the pump assembly 108 to move a fluid from the wellbore 104 to the surface through the production tubing 102 . Turning to FIGS. 2 and 3 , shown therein are elevational and cross-sectional views of the separator assembly 112 , respectively. The separator assembly 112 preferably includes an intake 116 , a chamber 118 , a neck 119 , and vents 120 . The intake 116 permits well fluid to enter the separator 112 and is preferably fitted with a screen 117 that blocks large pieces of rock, dirt or other debris that may be present in the wellbore. The chamber 118 acts as a conduit for the flow of fluid through the separator assembly 112 , and is generally defined to be cylindrically shaped by a housing 121 . The neck 119 is preferably situated towards the top of the separator assembly 112 , and in a presently preferred embodiment, is characterized by a narrowing of the housing 121 and includes vents 120 that link the chamber 118 to the wellbore 104 . The vents 120 may optionally include one-way valves 123 that restrict fluid flow by only allowing fluid to exit the chamber 118 . It will be understood that the size and angular disposition of the vents 120 can be varied to control the amount of fluid in the chamber 118 that exits the separator assembly 112 , as discussed in more detail below. The separator assembly 112 can also include a shaft 122 , an inducer 124 , an orifice plate 126 , and support bearings 128 , 130 . The inducer 124 , which is preferably affixed to the rotating shaft 122 by a keyed connection or other known methodology, imparts energy to the fluid as the inducer 124 spins with the rotating shaft 122 . The inducer 124 preferably increases the pressure in the chamber 118 to a level greater than the pressure in the wellbore 104 . The positive head pressure created by the inducer 124 prevents well fluid from flowing into the chamber 118 through vents 120 . For applications in which the separator assembly 112 is located between the pump 108 and the motor 110 , the shaft 122 also transfers rotational energy from the motor 110 to the pump 108 . Turning to FIG. 4 , shown therein is a top plan view of support bearing 128 . The support bearing 128 includes a sleeve 132 and a collar 134 . The sleeve 132 is fixed to the shaft 122 and the collar 134 is fixed to the housing 121 . The sleeve 132 rotates with the shaft 122 while the collar 134 remains stationary. The support bearing 128 is located in the chamber 118 where the fluid flows from the intake 116 to the top of the separator assembly 112 . To permit the flow of fluid through the chamber 118 , the support bearing 128 includes fluid passages 136 . In this way, the support bearing 128 provides axial alignment to the shaft 122 without hindering the flow of fluid through the chamber 118 . Turning now to FIG. 5 , shown therein is a top plan view of support bearing 130 . The support bearing 130 preferably includes a sleeve 132 fixed to the shaft 122 and a collar 134 fixed to the housing 121 . Because the support bearing 130 is positioned below the intake 116 , fluid passages are not necessary. Support bearings such as support bearing 130 do not require fluid passages if they are located in areas where the flow of fluid is not needed or desired. Turning to FIG. 6 , shown therein is a top plan view of the orifice plate 126 . The orifice plate 126 is fixed to the housing 121 of the separator assembly 112 and provides an orifice 138 through which well fluid flows out of the chamber 118 toward the pump 108 . The size of the orifice 138 affects the volumetric flow of fluid from the separator assembly 112 into the pump assembly 108 and recirculation. Various sizes of orifice 138 can be chosen to regulate fluid flow based on factors such as pump capacity and the desired flow of fluid in the separator assembly 112 . It will be understood that the movement of well fluid through the separator assembly 112 is caused by the cooperative operation of the motor 110 and the pump assembly 108 . During operation, well fluid enters the separator assembly 112 at intake 116 . As the well fluid in the chamber 118 reaches the vents 120 , well fluid from an outer diameter of the chamber 118 is diverted into the wellbore 104 through the vents 120 and the remaining portion of the well fluid in the chamber 118 flows toward the pump 108 . As well fluid exits the vents 120 into the wellbore 104 , gas in the vented fluid ascends toward the top of the wellbore and the remaining well fluid (with a higher concentration of liquid) descends toward the intake 116 for recirculation through the separator assembly 112 . As the recirculation continues, well fluid entering the separator assembly 112 becomes less encumbered with gas. The gas level of the well fluid in the separator assembly 112 thereby decreases with continuous recirculation of the vented well fluid. Because untreated well fluid is constantly introduced into the intake 116 from the perforations 105 in the well, the maximum reduction of gas content is limited by the amount of gas in the untreated well fluid. It is thought that the percentage by which the gas content of the well fluid is reduced is approximately equal to the percentage of well fluid vented into the wellbore from the chamber 118 after the system has reached a steady state. For example, well fluid from a formation that produces a gas concentration of twenty percent is expected to be reduced to a gas concentration of about ten percent if half the well fluid is vented back into the wellbore. Likewise, seventy five percent venting should result in a fluid stream of five percent gas content that reaches the pump. In the presently preferred embodiment, the vents 120 direct about fifty percent of the well fluid moving through the separator assembly 112 from the chamber 118 to the wellbore 104 . This amount can be varied by changing the size and angular disposition of the vents 120 , and by adjusting the size of the orifice 138 . If a greater reduction of gas is desired, more fluid should be vented and recirculated. Variations in recirculation rates can be chosen based on characteristics such as the performance of the pump and the gas content of the well. For example, some types of pumps that are sensitive to a high gas content will require more well fluid to be recirculated. Similarly, wells with a high gas content may also require more well fluid to be recirculated. The reduction of gas content is also affected by the amount of time the separator assembly 112 is in operation. The commencement of recirculation of fluid in the separator assembly 112 begins the process of reducing gas content from the level found in untreated well fluid. Only after sufficient time has elapsed will the separator assembly 112 reduce the gas content to the theoretical limit. The efficiency of the recirculation process depends at least in part on the amount of time in which gas is allowed to separate from liquid as it recycles outside the separator assembly 112 . The “separation time” can be controlled by adjusting the velocity of the recycle stream and/or the length of the recycle path. The velocity of the recycle stream can be controlled by varying the outer diameter of the separator assembly 112 with respect to the inner diameter of the wellbore 104 . The length of the recycle path can be controlled by modifying the length of the separator assembly 112 , and more particularly the distance between the vents 120 and the intake 116 . It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.	A submersible pumping system includes a pump, a motor that drives the pump and a separator assembly. The separator assembly is for separating gas from the fluid and includes an intake and a vent above the intake. Fluid enters the separator assembly at the intake and the vent returns a portion of the fluid into wellbore for recirculation into the intake.	4
BACKGROUND OF THE INVENTION The present invention relates to a drive system, more specifically relates to a drive system which is capable of moving a plurality of moving bodies. Conventionally, many types of drive systems have existed. Some of them were disclosed in Japanese Patent Kokai No. 63-191533, U.S. Pat. No. 2,857,032, No. 3,422,538 and No. 4,171,657, German Patent No. DE-36 28 202A, and European Patent No. EP-265-855-A. All of them are capable of moving one moving body to discretionary positions in a plane. Tools for machining, instruments for inspection or measurement, work to be machined, robot-heads, etc. can be attached to the moving body and are moved to prescribed positions for machining, etc. Those conventional drive systems, however, have the following disadvantages. A plurality of, for example, tools cannot be independently moved because each conventional drive system has only one moving body. In the case of moving a tool attached to a moving body along the locus shown in FIG. 12, a control program of a computer for controlling the movement of the moving body must be very complex and difficult to write. Further, the computer must have large memory capacity because of a complex program, so that drive systems must be very expensive. SUMMARY OF THE INVENTION First object of the present invention is to provide a drive system which is capable of moving a plurarilty of moving bodies independently. Second object of the present invention is to provide a drive system which is capable of moving a moving body along complex locus with a simple computer control program. To achieve above objects, the present invention has the following structures. To achieve the first object, a drive system comprises a plurality of two dimensional drive systems connecting each other, each of the two dimensional drive systems being capable of moving a moving body to discretionary positions in a plane by driving means. While, to achieve the second object, a drive system comprises a first two dimensional drive system being capable of moving a first moving body to discretionary positions in a plane by first driving means, and a second two dimensional drive system being capable of moving a second moving body, to which the first two dimensional drive system is provided, to discretionary positions in a plane by second driving means. In the former structure, a plurality of moving bodies are respectively moved by each of the two dimensional drive systems, so that each moving body can be moved independently. Therefore, when tools, robot-heads, etc. are respectively attached to each moving body, a plurality of tools, robot-heads, etc. can be moved independently, and efficient operation can be executed. In the latter structure, the movement of the first moving body and of the second moving body can be composed. Therefore, even if the locus for operating the tools, etc. is complex, the complex locus can be decomposed into the movement of the first and the second moving bodies. Therefore, each movement decomposed can be simpler locus, and the computer control programs also can be simpler. The memory capacity of the control computer may be small. The cost for making the program can be reduced. Further, the mass of the first moving body is smaller than of the second moving body, so that vibration can be suppressed when the first moving body turns because of small inertia. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and in which: FIG. 1 shows a plan view of a drive system of a first embodiment; FIG. 2 shows a front view, with portions broken away for clarity, of First Embodiment; FIG. 3 shows a plan view of one of two dimensional drive systems connected; FIG. 4 shows a plan view of another example of the two dimensional drive system; FIG. 5 shows a front view, with portions broken away for clarity, of an assembling machine using the drive system of the first embodiment; FIG. 6 shows a front view, with portions broken away for clearity, of a transforming machine using the drive system of the first embodiment; FIG. 7 shows a plan view of a drive system of a second embodiment; FIG. 8 shows a perspective view of a drive system of a third embodiment; FIG. 9 shows a perspective view of a drive system of a fourth embodiment; FIG. 10 shows a plan view of a drive system of a fifth embodiment; FIG. 11 shows a front view, with portions broken away for clarity, of a drive system of the fifth embodiment; FIG. 12 shows an explanation view of locus of a tool attached to the drive system of the fifth embodiment; FIGS. 13 and 14 respectively show explanation views of locus of the first and the second moving bodies for composing to make the locus shown in FIG. 12; FIG. 15 shows a plan view of a drive system of a sixth embodiment; and FIG. 16 shows a perspective view of a drive system of a seventh embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to accompanying the drawings. First Embodiment The first embodiment will be explained with reference to FIGS. 1-4. In FIGS. 1 and 2, a first two dimensional drive system 10 and a second two dimensional drive system 12 are connected to each other in a horizontal plane. A slider 14 as a moving body can be moved to discretionary positions in a rectangle plane 16 of the first two dimensional drive system 10; a slider 18 as a moving body can be moved to discretionary positions in a rectangle plane 20 of the second two dimensional drive system 12. The first two dimensional drive system 10 is mounted on a base 22; the second two dimensional drive system 12 is mounted on a base 24. Both bases 22 and 24 are connected by connecting means 26 to substantially form into one body. Next, the two dimensional drive systems 10 and 12 are explained with reference to FIG. 3. The structure of the first two dimensional drive system 10 only will be explained. The explanation of the second two dimensional drive system 12 will be omitted because both drive systems 10 and 12 have the same structure. FIG. 3 shows a plan view of the first two dimensional drive system 10 whose upper covers 30 and gear box covers 32 (see FIG. 1) are detached. The base 22 is formed into a rectangle frame shape and its center part is hollow. X-ball bearing screws 34 and 36 are mutually arranged in parallel in a horizontal plane. The X-ball bearing screw 34 is directly rotated by a motor 38; the rotational torque of the motor 38 is transmitted to the X-ball bearing screw 36 to rotate via a transmitting mechanism including bevel gears 42, a transmitting shaft 44, etc. The end portions of the X-ball bearing screws 34 and 36 are respectively and rotatably supported by gear boxes 56. Y-ball bearing screws 58 and 60 are mutually arranged in parallel in a horizontal plane, which is almost in the same level of the plane in which the X-ball bearing screws 34 and 36 are arranged, and the Y-ball bearing screws 58 and 60 are perpendicularly crossed with the X-ball bearing screws 34 and 36. The Y-ball bearing screw 58 is directly rotated by a motor 62; the rotation torque of the motor 62 is transmitted to the Y-ball bearing screw 60 to rotate via a transmitting mechanism including bevel gears 66, a transmitting shaft 68, etc. The end portions of the Y-ball bearing screws 58 and 60 are respectively and rotatably supported by gear boxes 56. X-travellers 82 and 84 are respectively screwed on the X-ball bearing screws 34 and 36. Both ends of a X-rod 90, which passes through the slider 14, are respectively fixed at the X-travellers 82 and 84. Thus, the X-travellers 82 and 84 are prevented from rotating by the X-rod 90, and both of the travellers 82 and 84 can be moved in the same direction when the X-ball bearing screws 34 and 36 synchronously rotate in the same direction. Y-travellers 86 and 88 are respectively screwed on the Y-ball bearing screws 58 and 60. Both ends of a Y-rod 92, which passes through the slider 14, and which perpendicularly crosses the X-rod 90 therein, are respectively fixed at the Y-travellers 86 and 88. Thus, the Y-travellers 86 and 88 are prevented from rotating by the Y-rod 92, and the both travellers 86 and 88 can be moved in the same direction when the Y-ball ball bearing screws 58 and 60 synchronously rotate in the same direction. The X- and Y-rods 90 and 92 pass through the slider 14 and mutually cross therein at the right angle, so that the slider 14 moves in the X-direction with the movement of the X-travellers 82 and 84; the slider 14 moves in the Y-direction with the movement of the Y-travellers 86 and 88. With this X-Y movement, the slider 14 can be moved to discretionary positions in the plane 16. Note that, the X- and Y-rods 90 and 92 may be made by metal rods having proper hardness and elasticity. In FIG. 3, the motors 38 and 62 are provided to the side faces of the gear box 56. However, the motors 38 and 62 may be provided to upper sections over the upper covers 30 with such connecting mechanisms (not shown) as gears, belt and pulley mechanisms, etc. If the motors 38 and 62 are provided to the upper section, there are no projected portions in all side faces of the first two dimensional drive system 10, so that four two dimensional drive systems can be respectively connected to each side face thereof. Note that, the reason why the second two dimensional drive system shown in FIG. 3 is adopted as the first and the second two dimensional drive systems 10 and 12 is that the positioning accuracy of the sliders 14 and 18 is quite high with above the described structure. Another example of the first and the second two dimensional drive systems 10 and 12 is shown in FIG. 4. Note that, some elements, which are the same as the elements shown in FIG. 3 are assigned the same numerals and the explanation thereof will be omitted. X-travellers 82 and 84 are capable of moving on an X-guide 100, which is spanned between gear boxes 56. The X-travellers 82 and 84 are respectively connected to endless belts 102 and 104, which are arranged in parallel in the X-direction. The endless belts 102 and 104 are driven by a motor 110 and a transmitting mechanism having a shaft 106 and pulleys 108. While, Y-travellers 86 and 88 are capable of moving on a Y-guide 112, which is spanned between gear boxes 56. The Y-travellers 86 and 88 are respectively connected to endless belts 114 and 116, which are arranged in parallel in the Y-direction. The endless belts 114 and 116 are driven by a motor 122 and a transmitting mechanism having a shaft 118 and pulleys 120. The above described structure, a slider 14 is capable of moving in a rectangle plane 16 with the rotation of the motors 110 and 112. Two examples of two dimensional drive system for the drive system of the first embodiment are shown in FIGS. 3 and 4 but other types of two dimensional drive system, e.g. U.S. Pat. No. 4,729,536, can be adopted. Note that, the examples of FIGS. 3 and 4, etc. can be adopted as two dimensional drive systems in the following embodiments. Successively, machines using the drive system of first embodiment will be shown in FIGS. 5 and 6. In FIG. 5, an assembling machine is shown. In the machine, robot-arms 208 and 209 are respectively attached to a slider 202 of a first two dimensional drive system 200 and a slider 206 of a second two dimensional drive system 204. The robot-arm 208 is capable of gripping parts 214 on a parts stage 212 and moving with the movement of the slider 202. While, the robot-arm 210 is capable of gripping parts 218 on a parts stage 216 and moving with the movement of the slider 206. The robot-arms 208 and 210 are able to assemble the parts 214 and 218 in the air or on an assembling stage 220 so as to make a product 222. The assembling process of the product 222 is monitored by a C.C.D.-camera 224. In this assembling machine, the robot-arms 208 and 210 can be mutually and independently operated. The positioning accuracy of the sliders 202 and 206 are quite high, so that high degree complex assembling can be executed. Note that, the movement of the slider 202 and 206 and the robot-arms 208 and 210 are fuzzy controlled by a computer. In FIG. 6, this machine is a transfer machine. A transferring mechanism 302 has a center block 300, whose plane position on the machine is fixed, and a transferring arm 304, which is capable of turning as shown by an arrow A by a motor 306. There is provided a sucker 308 at the front end of the transferring arm 304. The sucker 308 is connected to a vacuum generator (not shown) so as to suck and to release parts 310. There is attached a pallet 316 on which parts 310 have been previously arranged on a slider 314 of a first two dimensional drive system 312. While, there is attached a pallet 322 to which the parts 310 on the slider 314 are transferred on a slider 320 of a second two dimensional drive system 318. In this transfer machine, the sliders 314 and 320 change their plane position for every transferring operation because the locus of the transferring arm 304 cannot be changed. The parts 310 on the pallet 316 are sucked by the sucker 308, and the transferring arm 304 turns to the left. Upon reaching over the pallet 322, the sucker 308 releases the parts 310 so as to transfer the parts 310 to the pallet 322. Note that, a base 324 is not divided but is one body. In the example shown in FIGS. 1 and 2, the two dimensional drive systems 10 and 12 respectively have the bases 22 and 24, and both bases 22 and 24 are connected with each other. While, in the example shown in FIG. 6, the two dimensional drive systems 312 and 318 have a common base 324. In both cases, the two dimensional drive systems are substantially mounted on one base. If two or more two dimensional drive systems are located in one vibration system, mutual discrepancy of sliders can be suppressed. Second Embodiment The second embodiment will be explained with reference to FIG. 7. This drive system has four two dimensional drive systems 400, 402, 404 and 406, which are mutually connected in a plane. Tools, robot-heads, work, etc. can be attached to sliders 408, 410, 412 and 414, and they can be moved independently. Third Embodiment The third embodiment will be explained with reference to FIG. 8. In this embodiment, a couple of two dimensional drive systems 500 and 502 are combined three-dimensionally. The two dimensional drive systems 500 and 502 are connected with the right angle ("θ"). With this structure, for example, a work (not shown), which is located between the two dimensional drive systems 500 and 502, can be machined from two directions by tools 504, which are respectively attached to the two dimensional drive systems 500 and 502. Note that, the angle "θ" is not limited to a right angle. Fourth Embodiment The fourth embodiment will be explained with reference to FIG. 9. In this embodiment, three two dimensional drive systems 600, 602 and 604 are mutually combined with right angles. For example, a work (not shown), which is located among the two dimensional drive systems 600, 602 and 604, can be machined from three directions by tools 606, which are respectively attached to the two dimensional drive systems 600, 602 and 604. The drive system of the fourth embodiment can be combined with the drive system of former embodiments, so four or more two dimensional drive systems can be connected three-dimensionally. Fifth Embodiment The fifth embodiment will be explained with reference to FIGS. 10-14. In FIGS. 10 and 11, numeral 710 is a first two dimensional drive system whose slider 712 is capable of moving to discretionary positions in a rectangle plane 714. The slider 712 is controlled in its positioning by driving motors 716 and 718, which are controlled by a computer (not shown). The structure of the first two dimensional drive system 710 is the same as the two dimensional drive systems 10 and 12 of the first embodiment (see FIGS. 3 and 4), so that explanation is omitted. Numeral 720 is a second two dimensional drive system whose slider 724 is capable of moving to discretionary positions in a rectangle plane 722. The slider 724 is also in its positioning by driving motors 726 and 728, which are controlled by the computer. The first two dimensional drive system 710 is provided in the slider 724. The slider 724 is formed into a rectangle frame shape with hollow center section. The first two dimensional drive system 710 is fixed in the hollow center section by bolts (not shown), etc. The structure of the second two dimensional drive system 720 is almost the same as the first two dimensional drive system 710 except accommodating the first two dimensional drive system 710 in the slider 724 in a through-hole 760 and having a couple of X-rods 730 and a couple of Y-rods 732. In this embodiment, the height of the plane 714 in which the slider 712 moves and the height of the plane 722 in which the slider 724 moves are almost the same but they may not be the same. The first two dimensional drive system 710 may be provided on the upper and/or the lower side of the slider 724 of the second two dimensional drive system 720, and, in this case, the slider 724 need not be in the frame shape. In the double drive system of this embodiment, for example, if locus of tool 734, which is attached to the slider 712, is as shown in FIG. 12, locus of the slider 712 may be as shown in FIG. 13; locus of the slider 724 may be as shown in FIG. 14. Namely, composed movement of the sliders 712 and 724 will be the movement of the tool 734, so that the tool 734 is capable of moving with locus shown in FIG. 12. Each movement of the sliders 712 and 724 may be simple (see FIGS. 13 and 14), so that control program of the computer may be simple and easy to write. If pitch of ball-bearing screws 736 of the second two dimensional drive system 720 is designed to be larger than pitch of ball-bearing screws (not shown) of the first two dimensional drive system 710, the slider 724 can be moved at high speed; the slider 712 can be moved precisely at the same time. Thus, the tool 734, etc. can be precisely moved at high speed. Note that, in case that the sliders 712 and 724 are driven by timing belts as endless belts, the pitch of the timing belts for driving the slider 724 may be larger than the pitch of the timing belts for driving the slider 712, the fucnction will be the same as the system with such ball bearing screws. The slider 712 may be slantingly attached in two- or three-dimensional with respect to the slider 724. Namely, X-and Y-rods 738 and 740 of the first two dimensional drive system 710 may be slanting in two- or three-dimension with respect to X- and Y-rods 730 and 732 of the second two dimensional drive system 720. Further, other types of the first and/or the second two dimensional drive system can be adopted, and the shape of sliders (moving bodies) are also not limited. And two dimensional drive systems can be combined trebly or more. Sixth Embodiment The sixth embodiment will be explained with reference to FIG. 15. This embodiment is a combined embodiment of the first and fifth embodiments. The drive system has a first sub-drive system 800, which includes a first two dimensional drive system 804 and a second two dimensional drive system 806, and a second sub-drive system 802, which includes a first two dimensional drive system 808 and a second two dimensional drive system 810. A couple of sub-drive systems 800 and 802 are connected in a plane. The sliders 812 and 814 can be moved independently, and a computer can control their complex movement with a simpler program. Note that, three or more sub-drive systems can be connected in a plane. Seventh Embodiment The seventh embodiment will be explained with reference to FIG. 16. This embodiment is a combined embodiment of the third and fifth embodiments. A couple of sub-drive systems 900 and 902 are connected in three-dimensions. In this embodiment, for example, complex three-dimensional machining can be executed by tools 904. Note that, three or more sub-drive systems can be connected in three-dimensions. Now, preferred embodiments of the present invention have been described but the present invention is not limited to the above described embodiments. Many modifications can be allowed without deviating from the spirit of the invention.	Combining a plurality of two dimensional drive systems, a plurality of moving bodies can be independently moved by each of the two dimensional drive systems. Therefore, tools, robot-heads, work, etc. attached to the moving bodies can be moved independently. By attaching one of the two dimensional drive systems to another, the movement of both moving bodies are composed, so that the moving body of the one attached to another can be moved compositely. Therefore, the moving body or a tool, etc. attached thereto can be moved in a complex motion.	8
This is a continuation of copending application Ser. No. 07/749,645 filed on Aug. 26, 1991, now abandoned. BACKGROUND OF THE INVENTION The field of the invention is casters and the invention relates more specifically to shopping cart wheels. For more than twenty years, most high quality shopping cart wheels have utilized bearings which include a pair of all steel races and steel ball bearings. Such bearings are satisfactory for many uses but several trends exist which cause such bearings to be unsatisfactory. First, shopping carts are getting larger and are being used for heavier loads. Large hardware and wholesale outlets tend to lead to shoppers placing far more and far heavier goods in the shopping cart than was the case for the typical grocery shopper. Another tendency is the use of high-pressure washing systems to clean shopping carts. The carts are periodically placed in the parking lot of the supermarket and high-pressure detergent streams are used to clean the carts but, unfortunately, such streams often wash grease from within the steel wheel bearings. This often results in a very noisy bearing which makes the cart totally unacceptable to the store customers and employees. SUMMARY OF THE INVENTION It is an object of the present invention to provide a shopping cart with bearings which are capable of withstanding heavy loads and which are not degraded by high-pressure Washing systems. The present invention is for an improved shopping cart wheel of the type having a hub with a central axis of rotation, a central bisecting plane, and having an outer peripheral surface portion which supports a tire member. The hub also has a bearing support cavity surrounding the central axis of rotation. The improvement of the present invention comprises an opening surrounding the central axis of rotation about which first and second bearing supporting cavities are formed. A pair of female members are held by the first and second bearing support cavities, and the female race members are fabricated from a polymer, and each have an outwardly facing bearing race. A plurality of ball bearings are held adjacent the outwardly facing bearing race surfaces. A pair of male race members each has inwardly facing bearing races which are positioned facing the outwardly facing bearing race of the female race members. The male race members have an inner, generally cylindrical support cylinder which extends inwardly past the female race members to about the central bisecting plane of the hub and has a cylindrical inner surface. The bearing race extends away from the generally cylindrical support cylinder to form inwardly facing bearing races, and the male race member is also fabricated from a polymer. A cylindrical metallic inner shaft supporting sleeve supports the male race members along the cylindrical surface of the generally cylindrical support cylinder. Preferably, the female race member is fabricated from an acetal polymer, and the male race member is fabricated from nylon. There is also, preferably, a protrusion along the outer surface of the generally cylindrical support cylinder which holds the female race member in place after the ball bearings have been inserted. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded, perspective view of the improved shopping cart wheel of the present invention. FIG. 2 is a cross-sectional view of the shopping cart wheel of FIG. 1. DESCRIPTION OF THE PREFERRED EMBODIMENTS The improved shopping cart wheel is shown in perspective view in FIG. 1 and in cross-sectional view in FIG. 2 and indicated generally by reference character 10. Wheel 10 has a polymeric hub 11 which has a central bisecting plane 12 shown in FIG. 2 and a central axis of rotation 13 as shown best in FIG. 2. Hub 11 has a first bearing support cavity 14 and a second bearing support cavity 15. Cavity 14 has a vertical portion 16 and a cylindrical portion 17, and cavity 15 has a vertical portion 18 and a cylindrical portion 19. An Opening 20 surrounds the central axis of rotation 13. A tire 34 is cast over the outer peripheral surface 35 in a conventional manner. A pair of female race members comprising female race member 21 and female race member 22 are held in the first and second bearing support cavities 14 and 15, respectively. The construction of the female race member is an important feature of the present invention and it should be made from a polymer with excellent impact resistance and toughness. It has been found that an acetal polymer is satisfactory for this purpose. The female race members include outwardly facing races 23 and 24, respectively. A plurality of ball bearings are adjacent the outwardly facing races 23 and 24. A pair of male race members 26 and 27 also form an important portion of the present invention. Male race member 26 has an inner, generally cylindrical support cylinder 28, and male race member 27 similarly has a support cylinder 29. Male race members 26 and 27 each have an inwardly facing bearing race 40. Preferably, as shown in FIG. 2, these support cylinders 28 and 29 abut one another to provide a stop against overtightening of the races against the ball bearings 25. Male race members 26 and 27 each have a cylindrical inner surface 30 and 31 which snugly fit over the outer surface of a cylindrical, metallic inner sleeve 32. The axle passes through the inner surface of this sleeve. The sleeve tends to align and support the male race members 26 and 27 and likewise prevents the overtightening of the male race members against the female race members. That is, when a yoke is placed over the wheel assembly and riveted in place, both the cylindrical, metallic inner sleeve 32 and assembly in any detrimental way. Male race members 26 and 27 have a thread guard supporting rings 36 and 37 which support thread guards 38 and 39. Another important feature of the present invention is the material of construction of the male race members which should be fabricated from a polymer. The polymer should also be a tough, impact-resistant polymer, and it has been found that nylon is satisfactory for this use. It has also been found preferable that protrusions 33 be positioned on the outer surface of the support cylinders 28 and 29. This assists in the assembly of the unit whereby the female race can be snapped over the protrusions and held in place for later insertion into the bearing support cavities 14 and 15. The ball bearings 25, themselves, may be conventional steel ball bearings, but because the races are both polymeric, there will not be any squeaking as the ball bearings roll along the two polymeric races. The cylindrical, metallic inner sleeve 32 is preferably fabricated from steel so that it can provide maximum linear support and alignment of the male race members in addition to preventing undue pressure as set forth above. It has been found that wheels made according to the present invention will not require lubrication, will not rust, will be free wheeling and quiet and will last the life of the shopping cart wheel. The particular combination of acetal female race members with nylon male race members provides an excellent combination of strength, economy, and grease resistance over a wide range of temperatures. They provide an absence of "slip-stick" together with excellent abrasion resistance. The present embodiments of this invention are thus to be considered in all respects as illustrative and not restrictive; the scope of the invention being indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.	An improved shopping cart wheel which includes a hub which has bearing supporting cavities. The outer bearing is fabricated from a polymer, and the inner bearing is likewise fabricated from a polymer and has a cylindrical portion which extends into the center of the hub. This construction avoids the corrosion heretofore caused by cleaning solutions on the metal races.	1
FIELD OF THE IVENTION The invention relates to a steerable soil penetration system and method. BACKGROUND OF THE INVENTION Such a system is known from U.S. Pat. No. 5,163,520. In the known system a steerable penetration head is pivotally connected to a string of tubulars that are interconnected by screw thread connectors and that are pushed in a substantially horizontal direction through a shallow subsurface soil layer by a hydraulic ram, which is mounted in a trench or pit. The ram pushes the tubing string and associated penetration head through the soil and when the last tubing section has been substantially inserted into the created hole the ram is pulled back whereupon a new tubing section is added to the tubular string which is then pushed into the hole, which sequence of adding a new tubing section to the string and inserting it into the hole is continued until the penetration head has reached its target. US patent specification 2002/0000332, U.S. Pat. No. 4,856,600 and European patent application No. 0395167 disclose steerable rotary drilling systems which produce a large amount of drill cuttings. U.S. Pat. No. 5,850,884 discloses a moling apparatus which is not steerable. U.S. Pat. No. 4,955,439 discloses a steerable fluid jet drilling apparatus which will in use produce a large volume of fluidised drill cuttings. Other steerable soil penetration systems are known from U.S. Pat. Nos. 4,694,913; 5,070,948; 4,945,999; 4,306,626; 5,904,444; 5,878,825 and 4,981,181. The aforementioned U.S. Pat. No. 5,878,825 discloses a steerable penetration head, which is rotatably connected to a chain of short and rigid tubular elements that are interconnected by joints that are rotatable about a single axis. The chain of rigid tubular elements is pushed into the hole pierced by the steerable penetration head by an injector formed by a hydraulic piston assembly at the bottom of an injector pitch. Disadvantages of this known steerable soil penetration system are that the chain of rigid tubular elements interconnected by joints is complex, wear-prone, expensive and prone to buckling into a zig-zag configuration within the pierced hole, thereby significantly increasing the wall friction and inhibiting the penetration process. In addition, it requires a trench or pit. SUMMARY OF THE INVENTION In accordance with the present invention there is provided a steerable soil penetration system comprising a steerable penetration head which is connected to an elongate flexible tubing such that the orientation of the penetration head can be varied relative to the tubing and means for injecting the elongate flexible tubing into the hole pierced by the penetration head and for inducing the penetration head to extend the hole in a desired direction. The steerable penetration head in the system according to the invention is configured to penetrate the soil without the action of rotating cutters which means that the penetration head does not form a rotary drill bit which cuts away the soil ahead of the bit and which then produces drill cuttings that are to be removed from the borehole via an annulus surrounding the drill string. Since no cuttings are produced by the penetration head in the system according to the invention the annulus between the tubular string and borehole wall can be narrow, which is of benefit to the accuracy in which the system is steerable. Preferably the means for injecting the tubing into the pierced hole comprises a tubing injector assembly, which pushes the tubing into the pierced hole to provide thrust to the penetration head. In order to avoid buckling of the elongate flexible tubing when it pushes the penetration head forward the tubing preferably has an outer diameter, which is more than 80%, and more preferably more than 90%, of the largest outer width of the steerable penetration head. In one embodiment the flexible tubing is provided with conduits and/or electric cables for supplying power to the steerable penetration head. Alternatively or additionally, the flexible tubing can be equipped with electrical cables or optical fibres for data communication to and from the steerable penetration head. Suitably, said conduits, cables and fibres can be embedded in the wall of the flexible tubing. A suitable composite flexible tubing with electrical power cables embedded in the wall is disclosed in International patent application WO 0175263. Alternatively the flexible tubing may be a coilable steel tubing which may consist of a pair of coaxial steel tubulars wherein the electrical or other power and or transmission cables extend through the annular space between the inner and outer tubular. The elongate flexible tubing surrounded by a narrow annulus also serves as a hole lining which protects the hole against caving-in throughout and optionally also after completion of the hole piercing process. Optionally the elongate flexible tubing remains in the pierced hole to serve as a permanent hole lining and may be circumferentially expanded by inflation and/or an expansion device such as a mandrel or tractor to increase the internal width of the hole lining and optionally of the hole itself. The elongate flexible tubing may be equipped with a staggered pattern of relatively weak spots and/or openings, which break open and/or widen up to reduce the forces required to circumferentially expand the tubing wall. Suitably, the elongate flexible tubing is a steel tubular in which a staggered array of longitudinal slots is present, which slots traverse at least part of the wall in a radial direction. The slots may be filled with an elastomeric or other plugging agent which remains intact when the hole is being pierced, which agent is configured to break, rip, dissolve or otherwise losses its sealing function by e.g. mechanical and/or chemical disintegration when the tubing is circumferentially and/or radially expanded after completion of the piercing process. The steerable penetration head and/or flexible tubing may be provided with one or more repetitive shock generating, vibration and/or pulsating devices for enhancing the penetration rate of the penetration head through the soil in particular during a final phase of the hole piercing process. Also a vibration and/or shock generating device can be provided to reduce friction of the flexible tubing in the hole. Both these devices can be powered through said conduits or cables. Preferably the steerable penetration head comprises a sensor for detecting obstacles ahead of the penetration head, which sensor is connected to a steering mechanism that is capable of changing the orientation of the penetration head relative to the tubing such that the penetration head follows a curved trajectory to avoid detected obstacles. The steering mechanism preferably allows to steer the penetration head along a predetermined trajectory through the soil and to return to said predetermined trajectory after the penetration head has deviated form said trajectory to avoid a detected obstacle. The steerable penetration head may comprise a sensor and a real time positioning device for detecting the position of the head relative to a known fixed point. The steering system and the positioning system may interact and make it possible to follow the preset trajectory. Suitably, the steerable penetration head comprises a tapered nose section having a central axis that can be pivoted in any direction relative to a longitudinal axis of the tubing by the steering mechanism. To this end the tapered nose section may be connected to the tubing by a bendable tubular steering section, which can be induced by the steering mechanism to alternatingly obtain a straight or a curved shape. Said bendable tubular steering section may comprise memory metal, bimetallic, or technical ceramic (PZT) components which deform in response to temperature variations or to electrical voltage and one or more heating elements or electrical sources that are configured to vary the temperature or voltage of said components such that the bendable tubular section either obtains a straight or a curved shape. The bendable tubular steering section may either bend proportional or in an on/off non-proportional mode. In a suitable embodiment the bendable tubular steering section comprises at least three circumferentially spaced segments that are individually heated or cooled such that the lengths of the segments will vary and that the bendable tubular section either obtains a straight or a curved shape. Alternatively, the bendable tubular steering section is at one side weakened by perforations, slits or otherwise such that it will bend in a predetermined direction under the axial compression force exerted by the elongate flexible tubing and a stiff sleeve is movably arranged adjacent to the bendable tubular section such that the sleeve can be moved within or around the bendable tubular section to force the section into a substantially straight position and which can be retrieved from the bendable tubular to induce the bendable tubular section to bend under the axial compression force exerted by the elongate flexible tubing. In yet another embodiment of the system according to the invention the steerable penetration head may comprise a nose section which holds jetting nozzles which are geared to produce a hole in soft soil, hard soil and rock through which the elongated flexible tube is pushed in. The jetting devices can be actuated independently and produce enough radial trust to bend the head assembly in the desired direction. In this embodiment the elongated flexible tube will also hold tubes through which jetting fluids is moved to the penetration head and the jetting nozzles and cables for controlling the nozzles. The method according to the invention for piercing an at least partially horizontal hole in a subsurface formation with a steerable soil penetration system comprises the step of exerting a thrust force to a steerable penetration head which compacts the surrounding soil substantially in the absence of rotating cutters by an elongate flexible tubing and/or downhole propulsion means thereby inducing the penetration head to extend the hole in a desired direction. Optionally, at least part of the elongate flexible tubing is left behind in the pierced hole to serve as a permanent hole liner and at least part of the elongate flexible tubing may be circumferentially expanded after completion of the piercing process such that the expanding tubing radially expands the pierced hole to a larger internal width. The expansion process may create a predetermined pattern or track in the permanent hole liner, which could be used by the expansion device or tractor to propel itself forward. In some embodiments of the present invention includes a system and method for creating a hole in a subsurface formation, wherein a small diameter pilot hole is pierced into the formation which pilot hole is subsequently expanded to an encased larger diameter hole in which one or more fibre optical, electrical and/or other cables and/or fluid transportation conduits are inserted, or which hole may serve as a subsurface fluid transportation and/or drainage conduit. In some embodiments of the present invention includes is to provide a cost effective system and method for creating a grid of shallow holes in a subsurface formation in urban and other areas, in which holes strings of aeophones and/or fibre optical sensing devices can be permanently inserted for monitoring seismic reflections and/or other geophysical effects during an extensive period of time, with a minimum impact on the environment at the earth surface. In some embodiments of the present invention includes is to provide a system and a method for creating a hole in a subsurface formation to accommodate transmission systems such as tubes, pipes, hoses, cables, rods and bars or hole preservation systems such as conduits, ducts and casings or which can be used as a pilot or guidance hole for reaming or otherwise enlaraing the hole. BRIEF DESCRIPTION OF THE DRAWING The foregoing and other features, objects, applications and effects of the method and system according to the invention will become more apparent from the following more detailed description of preferred embodiments of the invention in which reference is made to the accompanying drawings, in which: FIG. 1 is schematic longitudinal sectional view of a shallow hole, which is being pierced into a subsurface formation by a steerable hole penetration system according to the invention; FIG. 2 is a schematic longitudinal sectional view of the thus pierced hole in which an elongate flexible tubing is circumferentially expanded to increase the internal width of the hole; and FIG. 3 is a more detailed longitudinal sectional view of the penetration head of the steerable hole penetration system shown in FIG. 1 . DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1 , there is shown a steerable hole penetration system comprising a steerable penetration head 1 , which is rotatably and pivotably connected to an elongate flexible tubing 2 by a steering mechanism 3 . The tubing 2 is unreeled from a reeling drum 4 at the earth surface and pushed into the hole pierced by the penetration head 1 by a tubing injector assembly 6 . Adjacent to the tubing injector assembly 6 a tubing guide pipe 7 is screwed in an inclined position into the topsoil. Alternatively said guide pipe 7 may be hammered or drilled into the topsoil. The guide pipe 7 safeguards a stable and pressure tight launch pad for the flexible tubing 2 into the hole. After the soil has been removed from the interior of the tubing guide pipe 7 a wedge 9 is inserted near the bottom of said interior and the penetration head 1 is pushed into the underlying earth formation 8 by the thrust exerted by the tubing injector assembly 6 via the tubing 2 to the penetration head 1 . The steering mechanism 3 is configured to orient the penetration head 1 either in a substantially aligned or in a slightly misaligned direction relative to the elongate flexible tube 2 in which case either substantially straight or slightly curved hole sections will be pierced. FIG. 3 shows in more detail the penetration head 1 and steering mechanism 3 of the steerable hole penetration system of FIG. 1 . The steering mechanism 3 comprises a first tubular section 3 A which is rotatably connected to a proximal end 2 A of the elongate tubing 2 by a first hollow shaft 30 which is at one end connected to a first electrical motor and gear mechanism (not shown) inside the orientation control unit 31 and at another end to the first tubular section 3 A by means of a series of radial spacers 32 . The steering mechanism 3 furthermore comprises a second tubular section 3 B which is rotatably connected to a slant proximal end 3 C of the first tubular section 3 A by a second hollow shaft 33 which co-axially surrounds the first hollow shaft 30 and which is at one end connected to a second electrical motor and gear mechanism (not shown) inside the orientation control unit 31 and at another end to the second tubular section 3 B by means of a series of radial spacers 34 . Rotation of the second tubular section 3 B relative to the first tubular section 3 A of the steering mechanism 3 will as a result of the slant orientation of the proximal end 3 C cause the penetration head 1 to obtain a slightly deviated orientation relative to the central axis 35 of the elongate flexible tubing 2 in which case a slightly curved hole section is pierced. The angular orientation of the curved hole section relative to the central axis 35 is simultaneously controlled by rotating the first tubular section 3 A relative to the proximal end 2 A of the elongate flexible tubing 2 . The steering mechanism 3 may be made of a composite shock absorbing material and/or comprise one or more shock absorbers (not shown). Inside the first hollow shaft 30 and the orientation control unit 31 a central opening 36 is present in which an umbilical electrical cable bundle 37 is secured by means of a series of spacers 38 . The central opening 35 also serves as a fluid injection conduit through which a lubricating and cooling liquid is injected into an annular space 40 between the elongate tubing 2 and the inner wall 41 of the pierced hole as illustrated by arrows 42 . Preferably said liquid is injected at low speed into the annular space 40 in order to inhibit creation of wash outs of the pierced hole by jetting action. The penetration head 1 is at least during an initial stage of the piercing process pushed forward through the subsurface formation 8 by the thrust exerted by the tubing 2 , thereby compacting and/or pushing aside the formation in the immediate vicinity of the penetration head 1 . When a substantial length of tubing 2 has been injected into the hole, friction between the tubing 2 and the inner surface 41 of the hole will reduce the thrust exerted to the penetration head 1 . To stimulate the progress of the penetration process the penetration head 1 is vibrated in an axial and/or radial direction relative to the tubing 2 and steering mechanism 3 by means of a hammer 44 and anvil 45 assembly which are vibrated relative to the second tubular section 3 B and relative to each other by means of an electromagnetic linear motor 46 and which receives electric power from the electric power cable bundle 37 via a inductive coupling 47 . The inductive coupling 47 also provides electric power to an electronic sensing and control unit 48 which senses acoustic reflections of the impacts exerted by the penetration head 1 to the formation 8 in order to identify any obstacles within the formation 8 ahead of the penetration head 1 . The inductive coupling 47 and electrical umbilical cable bundle 37 serves as bi-directional power and signal transmission umbilical between an electrical power and control unit (not shown) at the earth surface and the downhole electronic sensing and control unit 48 within the penetration head 1 . In the embodiment shown in FIGS. 1 and 3 the penetration head 1 comprises a tapered main section in which a cylindrical nose section 1 A is inserted such that the penetration head 1 is substantially rotational symmetrical to the central axis 35 of the penetration system. In an alternative embodiment the penetration head 1 may have a frontal surface that permanently has a slant orientation relative the central axis 35 such that the penetration head 1 will create a curved hole in which case the steering mechanism 3 may comprise a single rotatable section 3 A only, or comprise an array of three circumferentially spaced, for example a bi-metallic, memory or electrically activated metal, or voltage responsive PZT ceramic segments (not shown) which may individually contract away from or expand against the inner wall 41 to steer the penetration head 1 such that it follows a predetermined trajectory or circumvents any subsurface obstacles 50 detected by the downhole sensing and control unit 48 and subsequently returns to said predetermined course as indicated by the dotted line 51 in FIG. 1 . Alternatively the steering system may comprise a set of three hybrid bi-metallic and hydraulic assemblies that are known as smart rams. FIG. 2 . shows how after completion of the piercing process the elongate flexible tubing 2 is circumferentially expanded by an expansion device 55 , which is pulled through the tubing 2 by winding a cable 56 around a drum 57 . An electrical cable 59 and a flexible fluid transportation conduit 58 are simultaneously pulled into the expanded tubing 2 by the expansion device 55 . The expansion device 55 may comprise an expansion mandrel and/or rollers and a traction unit (not shown), which propels the device 55 forward through the tubing 2 . The tubing may comprise a staggered array of weak spots, which open up or expand during the expansion process. The traction unit may comprise spikes, which penetrate through the thus created openings to generate a sufficient thrust to the expansion device 55 such that the tubing is expanded and the borehole width is simultaneously increased by the expanding tubing 2 . While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be readily apparent to, and can be easily made by one skilled in the art without departing from the spirit of the invention. Accordingly, it is not intended that the scope of the following claims be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all features which would be treated as equivalents thereof by those skilled in the art to which this invention pertains.	A steerable soil penetration system having a steerable penetration head, which compacts and does not cut away the surrounding soil and which is connected to an elongate flexible tubing such that the orientation of the penetration head can be varied relative to the tubing. The elongate tubing and/or a downhole hammer or tractor pushes the penetration head through the subsurface formation. Preferably the tubing is surrounded by a narrow annulus so that buckling of the tubing is inhibited and the tubing protects the pierced hole against caving in. Optionally the tubing is circumferentially expanded after completion of the piercing process thereby increasing the width of the pierced hole and providing a permanent hole lining.	4
[0001] This application claims benefit of the 30 Sept. 2008 filing date of U.S. provisional application 61/101,481. FIELD OF THE INVENTION [0002] This invention relates generally to the field of fluid pressure monitors for ambient air conditions for rooms, and to the calibration of such monitors. BACKGROUND OF THE INVENTION [0003] Fluid pressure monitors are used in a large variety of applications over a wide range of pressures and with varying requirements for accuracy. Very low differential ambient air pressures, on the order of a full scale range of 0.1 inch of water or less, must be measured with a high degree of accuracy in applications such as manufacturing clean rooms, medical isolation wards, and various HVAC systems. Periodic calibration of such devices is required to ensure and to document their proper operation. [0004] U.S. Pat. No. 5,693,871, incorporated by reference herein, describes a pressure generator that may be used to calibrate differential pressure transducers that operate at very low differential pressures. [0005] U.S. Pat. No. 6,584,421, also incorporated by reference herein, describes an instrument calibration device that incorporates a portable computer as its user interface in order to simplify the use of the device for calibrating a variety of instruments and for recording the results of such calibrations. BRIEF DESCRIPTION OF THE DRAWINGS [0006] The invention is explained in the following description in view of the drawings that show: [0007] FIG. 1 is a schematic illustration of a room pressure monitoring apparatus in an operational configuration. [0008] FIG. 2 is a schematic illustration of the room pressure monitoring apparatus of FIG. 1 in a calibration configuration including a portable calibration module. [0009] FIG. 3 . is a schematic illustration of the room pressure monitoring apparatus of FIG. 2 in a further calibration configuration. [0010] FIG. 4 is a Starting screen display of the monitoring module of the room pressure monitoring apparatus of FIG. 1 . [0011] FIG. 5 is a Menu screen display of the monitoring module of the room pressure monitoring apparatus of FIG. 1 . [0012] FIG. 6 is a Calibration screen display of the monitoring module of the room pressure monitoring apparatus of FIG. 1 . DETAILED DESCRIPTION OF THE INVENTION [0013] The assignee of the present invention provides calibration equipment for instrument calibration service that satisfies ISO documentation standards requirements, that is performed in compliance with ANSI/NCSL Z540-1-1994, and that is certified per NIST traceable primary standards. For the owners and operators of large numbers of pressure transducers, on-site calibration may be an economically viable alternative to shop-based calibration. Portable calibration devices, such as the Model 869 Micro-Cal™ calibration system sold by the assignee of the present invention, provide the capability to deliver a highly accurate calibration source directly to the location of a pressure monitoring installation. A pressure transducer is removed from its operating position, inserted into the Model 869 Micro-Cal™ calibration system, and then reinstalled immediately following the calibration procedure, thereby avoiding the downtime and expense associated with shipment to a central calibration service location. [0014] FIGS. 1-3 are schematic illustrations of an improved pressure monitoring apparatus 10 in various configurations, such as may be used for low differential pressure applications for example. A monitoring module 12 of the pressure monitoring apparatus 10 is illustrated in FIG. 1 in an operational configuration as it functions as an active transducer in an operating system, such as a room pressure monitoring application. A monitored pressure (room pressure) and a reference pressure are provided to the device by respective room and reference pressure lines 14 , 16 . A differential pressure sensor 18 of any known type, such as capacitive, inductive, strain gauge for example, converts the difference in pressure between the two lines 14 , 16 into an electrical signal 21 , such as a frequency output proportional to measured pressure. An electrical terminal 22 is provided for removable electrical connection of the appropriate monitoring module electrical connections 20 to various external electrical interfaces 24 , such as a power supply, remote display, remote controller, etc. For simplification of the drawings, electrical connections are illustrated in these figures as single lines that may represent a plurality of power, control and/or signal functions as known in the art. A controller 26 , such as any known microprocessor and memory (EPROM), provides the appropriate control, memory and processing functions and operatively interconnects the various components of the monitoring module 12 . User interface may be provided by an input/output device or devices such as touch screen 28 . All of these components may be supported directly or indirectly by a frame 30 that is mountable to a wall, rack or other desired support structure or surface. [0015] The apparatus 10 also includes a monitoring module plug 32 that may be selectively attached or removed from the monitoring module 12 . The monitoring module plug 32 provides a plug-in connect/release fluid connection between the room and reference pressure lines 14 , 16 and respective pressure ports 34 , 36 of the differential pressure sensor 18 . The pressure lines 14 , 16 may be installed over barbed tips to provide a tight fluid seal and strong mechanical connection which need not be disturbed during subsequent calibration procedures. The fluid seal between the monitoring module plug 32 and the monitoring module 12 may include a flexible gasket or O-ring (not shown). Additionally, the plug may be held in place once installed on the monitoring module 12 by friction or by any type of known locking device, such as screws or clips for example (not shown). [0016] The monitoring module plug 32 may also include electrical conductor(s) that provide plug-in connect/release electrical continuity between the electrical terminal 22 and the various other electrical connections 20 of the monitoring module 12 when the plug 32 is installed on the monitoring module 12 . One embodiment of the monitoring module plug 32 was made by modifying a standard D-sub electrical connector to include fluid passages in the location normally occupied by the screw fasteners. Accordingly, when the monitoring module plug 32 is disconnected from the monitoring module 12 /frame 30 , the pressure ports 34 , 36 and the electrical connections 20 are disconnected from the respective pressure lines 14 , 16 and external electrical interfaces 24 . [0017] FIG. 2 illustrates the pressure monitoring apparatus 10 in a calibration configuration where the monitoring module plug 32 has been removed, thereby making the pressure ports 34 , 36 and the electrical connections 20 available for connection to a portable calibration module 42 . The calibration module 42 includes a calibration pressure source 44 such as the pressure generator described in U.S. Pat. No. 5,693,871 discussed above. The calibration pressure source 44 provides precise, controllable and repeatable fluid pressures to pressure outlets 46 , 48 . These pressure outlets are selectively fluidly connected to the monitoring module pressure ports 34 , 36 by an electro-pneumatic interface 49 . The electro-pneumatic interface 49 is connected at its proximate end to the calibration module 42 in any desired manner. At its distal end, the electro-pneumatic interface 49 may include a calibration module plug 50 adapted for selective installation on the monitoring module 12 /frame 30 in place of the monitoring module plug 32 to enable calibration of the pressure sensor 18 . The electro-pneumatic interface 49 includes fluid passages 52 , 54 for interconnecting the monitoring module pressure ports 34 , 36 with the calibration module pressure outlets 46 , 48 , and it also includes electrical conductor(s) 56 for interconnecting calibration module electrical connections 58 with the monitoring module electrical connections 20 . Here again, to simplify the drawings, all power, control and signal conductors are graphically illustrated as a single line. Also, no power supply is illustrated, but one skilled in the art will appreciate that a battery pack or other source of power would be associated with the portable calibration module 42 . The electro-pneumatic interface 49 may be fabricated as a single integrated Electro-pneumatic Interface Cable (EPIC), although one skilled in the art will recognize that multiple cables/plugs may be used in other embodiments to accomplish similar functions. [0018] As can be seen in FIG. 2 , the external electrical interfaces 24 are isolated from the monitoring module in the calibration configuration, and the monitoring module electronic components 26 , 28 are interconnected with the calibration module processor 60 . Interrogation, control and operation of the monitoring module 12 may be accomplished via the calibration module 42 in this configuration. For example, an EPROM of controller 26 may be interrogated by the calibration module 42 to identify the type of monitoring module 12 that is connected to the EPIC, whereupon data related to that identity may be recalled from memory and used by the calibration module 42 , such as for automatically selecting an appropriate full scale pressure for the calibration process, or an accuracy code, or a serial number as examples. The processor 60 may then execute programmed instructions for automatic calibration of the monitoring module 12 , such as: [0019] apply a zero differential pressure across the pressure outlets 46 , 48 (thereby across the pressure ports 34 , 36 via fluid passages 52 , 54 ); [0020] setting a resulting output of the pressure transducer 18 to a desired zero value by responsively programming data in EPROM of controller 26 ; [0021] applying the previously determined full scale pressure across the pressure outlets 46 , 48 ; and [0022] setting a resulting output of the pressure transducer 18 to a desired full scale value by responsively programming data in EPROM of controller 26 . [0023] The zero differential pressure may be accomplished within the calibration module 42 by appropriate control of valves 61 to shunt both sides of the calibration pressure source 44 to atmosphere. [0024] As can be seen in FIG. 2 , the calibration module plug 50 includes monitoring module interface connections 62 for selective connection with the monitoring module 12 . In addition, the calibration module plug 50 may have operating system interface connections 64 on an opposed side for selective connection with the operating system fluid connections via the monitoring module plug 32 , as illustrated in FIG. 3 . In the configuration of FIG. 2 during the above-described calibration steps, the operating system interface connections 64 are closed with a blank plug 66 . After the calibration steps have been completed, the blank plug 66 may be removed and replaced with the monitoring module plug 32 previously described with reference to FIG. 1 . This allows the pressure ports 34 , 36 as well as the calibration module pressure outlets 46 , 48 to be exposed to pressure generated in the monitored operating system and delivered by the room and reference pressure lines 14 , 16 . This configuration is useful for comparing and recording data generated by the pressure sensor 18 /monitoring module 12 and data coincidently generated by the calibration module 42 in response to actual system pressures delivered via the room and reference pressure lines 14 , 16 . In this manner, the monitoring module 12 , the calibration module 42 and the system operator's supervisory monitoring system may be reconciled. [0025] The pressure monitoring apparatus 10 enables calibration of the monitoring module 12 without removing the device from its operational location, and without removing any hard wired connection from the electrical terminal 22 , and without removal of tubing for pressure lines 14 , 16 from the monitoring module 32 . Furthermore, the touch screen user interface device 28 provides further capability for in-situ calibration of the device. Programmed code may be executed by the controller 26 for providing a simplified user interface for calibration via the touch screen 28 . FIG. 4 illustrates a Starting Screen display 68 as may be provided during normal operation of the pressure monitoring apparatus 10 . The real-time measured pressure may be displayed as a numeric value 70 and/or as a graphical presentation 72 showing the location of the real-time actual value in relation to the alarm setpoint limits. The real time display of the entry door status may also be displayed via the touch screen display 28 by a text message or by using color change indication. In addition, Silence and Reset buttons 74 , 76 may be provided for the operator to use in response to an alarm. The alarm may be provided by an auxiliary device, such as a sound generating device and/or a light emitting device, and/or the alarm may be displayed on the touch screen 28 via a color indication, flashing display or other manner. A Menu selection 78 may also be provided on the Starting Screen display 68 . [0026] In response to a touch of the Menu selection 78 , a Menu Screen 80 is displayed as illustrated in FIG. 5 . The Menu Screen 80 includes Setup selections 82 , a Test selection 84 and a Calibration selection 86 . [0027] In response to a touch of the Calibration selection 86 , a Calibration Screen 88 is displayed, as illustrated in FIG. 6 . The Calibration Screen 88 includes a Zero selection 90 and a Span selection 92 . Upon removal of the monitoring module plug 32 from the frame 30 (thereby exposing the pressure ports 34 , 36 to the same atmospheric pressure and a zero pressure differential) and in response to a touch of the Zero selection 90 , the controller 26 may be programmed to set the output of the pressure sensor 18 to a desired zero value (e.g. 0 volts DC or 4 ma, for example) by appropriate data recordation in the controller EPROM. A known full scale pressure may then be applied to the measured room pressure port 34 , and in response to a touch of the Span selection 92 , the controller 26 may similarly set the output of the pressure sensor 18 to a desired full scale value (e.g. 10 volts DC or 20 ma, for example). Thus, calibration of the unit is accomplished in a rapid and convenient manner without the removal of the monitoring module 12 from its operating location. [0028] While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.	A pressure monitoring apparatus ( 10 ) including features that simplify in-situ calibration procedures. A pressure monitoring module ( 12 ) of the apparatus is coupled to external pressure lines ( 14, 16 ) and an external electrical interface ( 24 ) via an easily removable monitoring module plug ( 32 ). The monitoring module can be disconnected from the pressure lines and external interface and then connected to a portable calibration module ( 42 ) by simply replacing the monitoring module plug with a calibration module plug ( 50 ). The calibration module plug provides an electro-pneumatic interface between the monitoring module and the calibration module. The monitoring module may be electronically interrogated and automatically calibrated via a processor of the calibration module. The monitoring module plug may be inserted onto the calibration module plug to provide actual system pressures to the now-calibrated apparatus for final documentation. Touch-screen ( 28 ) interface with the monitoring module provides an one-touch calibration of Zero and Span.	6
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/IB2005/003360 filed on Nov. 9, 2005, which claims the benefit of Italian Patent Application No. TO 2004 A 000776 filed Nov. 9, 2004. The disclosures of the above applications are incorporated herein by reference. FIELD The present disclosure relates to a device for dynamic control of a water flow as it is employed to stabilize the function of a thermostatic mixer. BACKGROUND The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Thermostatic mixers, which are suited to handling a large flow do not function properly if the flow that is demanded from them is much smaller than the maximum flow for which they are designed, which occurs, for example, when a thermostatic mixer intended for supplying a system with multiple shower units is used to supply a single shower unit. Under these circumstances, thermostatic mixers lose their stability and begin to oscillate so that the water flow piped from them is subjected to constant changes in the ratio of cold to warm water and thus sustains temperature fluctuations, which are unpleasant for the user and can even be harmful. This disadvantage can be eliminated by having the flow of cold water supplying the thermostatic mixer opposed by a resistance when small flows of mixed water are demanded, while suppressing or reducing this resistance when large flows of mixed water are demanded. This process is triggered automatically by devices for dynamic control of flow, in which it is provided that the passage cross section made available for the incoming cold water is to be reduced when the admitted flow is reduced and a larger passage cross section is to be restored when a greater flow is demanded. However, the prior art devices for dynamic control of flow generally have the disadvantage of featuring pistons that are acted upon in one direction by the pressure of the incoming water and in the other direction by a return spring. The load of the spring must therefore be adjusted according to the inlet pressure of the cold water. This means that on one hand, the device must be adapted during installation to the pressure conditions present in the system for the sake of correct functioning, while on the other hand, the device no longer functions properly when considerable variations in the inlet pressure of the cold water appear. SUMMARY The main task of the present invention is to produce a device for the dynamic control of a flow, the functioning of which in a broad range of applications must be independent of inlet pressure, so that during installation the device must not require any adjustments and must then not function improperly when considerable variations in inlet pressure appear. An additional task of the present invention is to produce a device of this type for the dynamic regulation of flow that is of simple construction and is economical, while ensuring a high degree of reliability and a long life. An additional task of the present invention is to produce a device of this type that can be fitted into a stopcock, with which thermostatic mixers are often equipped, so that no additional element must be incorporated into the system. According to the invention, these problems are solved with a device for the dynamic control of a flow comprising, in a body, an inlet fitting, an inlet chamber, an outlet chamber, a piston, which is arranged between the inlet chamber and the outlet chamber and can be moved between a first position, which is displaced to the inlet chamber, wherein the piston constricts the flow between the inlet chamber and the outlet chamber when in the first position, and a second position, which is displaced to the outlet chamber, wherein the piston does not constrict the flow between the inlet chamber and the outlet chamber when in the second position, and a return spring, which acts upon the piston to move it to the first position, characterized by the fact that the inlet chamber is at least partly ring-shaped and encloses the piston, that the piston comprises a cylindrical shell section arranged in the area of the inlet chamber and a transverse segment, which defines an intermediate chamber and is crossed by an axially limited passage, that a flow-limiting means is arranged between the inlet fitting and the intermediate chamber, and that the axially limited passage and the return spring are proportional to one another so that the effect of the spring is essentially equal to the force that acts to shift the piston out of the first position and into the second position, when the maximum flow allowed by the flow-limiting means is discharged. In this way, the piston cannot be displaced by the inlet pressure, since this force is exerted radially and this process, whatever its value may be, does not tend to displace the piston out of its first position and into the direction of its second position. The pressure which builds in the intermediate chamber is determined through the drop in pressure sustained by the flow when passing from the inlet fitting to the intermediate chamber via the flow-limiting means. The effect exerted on the piston axially and in the opposite direction such as that of the return spring is based essentially on the difference between the pressure prevailing in the intermediate chamber and the pressure prevailing in the outlet chamber, which, due to the drop in pressure sustained by the flow when passing through the axially limited passage present in the transverse section of the piston is smaller than the former pressure. This pressure differential acts upon the transverse section of the piston and works to overcome the force of the return spring. Suitable dimensions for the cross section of the limited passage present in the transverse section of the piston, the strength of the return spring and the characteristics of the flow-limiting means in turn make it possible for the piston not to shift out of its first position and into its second position, as long as a flow is discharged that is smaller than the maximum flow that can trigger instability in a thermostatic mixer. If, however, a flow is demanded from the outlet chamber that is greater than that defined above, the drop in pressure occurs in the outlet chamber so that the pressure differential acting on the piston exceeds the force of the return spring, and the piston then is displaced into its second position, whereby it allows the flow to pass from the inlet chamber to the intermediate chamber and then to the outlet chamber. Because the displacement of the piston is regulated or controlled not by the absolute pressure prevailing in the chambers of the device, but rather by the pressure differential between the intermediate chamber and the outlet chamber, which depends on the flow and the resistances resisting it, but not on the absolute pressure, the function of the device is to a large extent independent of the inlet pressure, and the device in turn requires absolutely no adjustments during installation and exhibits no irregularities in function, even when the inlet pressure varies considerably. The flow-limiting means used in the inventive device is a widely available, low-cost valve of the prior art and is described for example in various forms in patent documents DE 40 41 116, DE 102 20 287, DE 102 28 490 and WO 01/04714. This valve provides the flow with a passage with reduced resistance as long as the flow volume of the flow does not exceed a limit preset through the construction of the flow-limiting means, while the valve, if the flow shows a tendency to exceed this limit, places a resistance against the flow, thereby limiting the flow to the maximum allowable value. Valves of this type are often fitted in devices, such as showers for example, in which the consumption must be limited—for legal reasons in certain cases. Because these valves are available for many different threshold values for flow, an adequate selection of the flow-limiting means and an appropriate proportioning of the parts of the device in the way described above are thus sufficient for creating an inventive flow-regulating device that can be adapted to the necessities of various specific applications. The intermediate chamber in the body of the device is advantageously limited through the inlet fitting, in which an intake chamber is defined and which features a transverse wall, in which axial circumferential passages are formed, which open into the ring-shaped inlet chamber, which encloses the piston, while the flow-limiting means is installed in the center of the transverse wall. The intake chamber and the axial circumferential passages can be formed from passages that are contained in a supplementary element, which is disposed between the body of the device and the inlet fitting, of which it is a part. This supplementary element can be advantageously manufactured from a synthetic material. In its first closing position, the piston can abut an even surface of the inlet fitting, or it can partly engage a seat formed by the surface. Given the extreme simplicity of the inventive device and its reduced dimensions, it is possible to fit it into a stopcock. Because thermostatic mixers are often provided with a stopcock for the purpose of simplifying maintenance, it is thus possible to install in series to the thermostatic mixer a single supplementary part that contains both the stopcock and the device for the dynamic regulation of flow instead of having to fit two different supplementary parts. It is advantageous, particularly during the process of fitting, if the direction of piston displacement and the axis of a closing element of the stopcock coincide. Furthermore, a stopcock containing the inventive device is also a part of the invention. Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. FIG. 1 represents an axial section of a device for dynamic control of a flow in accordance with a first embodiment of the present invention in a resting state or operating with reduced flow. FIG. 2 represents the same device shown in FIG. 1 in a state of operating with increased flow. FIGS. 3 and 4 represent a second embodiment of the inventive device analogous to FIGS. 1 and 2 . FIGS. 5 and 6 represent a third and fourth, respectively, embodiment of the invention in a resting state. FIGS. 7 and 8 represent a fifth embodiment of the invention in a resting state and a state of operating with increased flow, respectively. FIG. 9 represents how the device as illustrated in FIG. 6 can be fitted into a stopcock shown in a resting state. FIG. 10 represents the stopcock as illustrated in FIG. 9 in a state of operating with heavy flow. DETAILED DESCRIPTION The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. FIGS. 1 and 2 represent an axial section of a device for the dynamic control of a water flow of the type employed for the purpose of stabilizing the function of a thermostatic mixer, which comprises a body 1 , which in this case is completed on top by an inlet fitting 3 and forms an outlet fitting 4 . The inlet fitting 3 forms an intake chamber 5 in its interior, while the outlet fitting 4 forms an outflow passage 6 in its interior that is connected to an outlet chamber 7 that occupies the interior of the body 1 . Displaceably arranged in the outlet chamber 7 is a piston 8 , which features a cylindrical shell section 9 and a transverse section 11 crossed by an axially limited passage 12 . The shell section 9 and the transverse section 11 of the piston 8 define an intermediate chamber 16 . Formed in the body 1 and encircling the shell section 9 of the piston 8 is a ring-shaped inlet chamber 13 , which is defined by a transverse wall 19 of the inlet fitting 3 and is supplied by the intake chamber 5 via axial circumferential passages 2 , which is provided in the transverse wall 19 of the inlet fitting 3 . In the body 1 , the outlet fitting 4 is defined by a transverse wall 14 crossed by a passage 15 . Arranged between this wall 14 and the piston 8 is a spring 17 , which in turn presses the piston 8 with the edge of its shell section 9 against the transverse wall 19 of the inlet fitting 3 , which defines the inlet chamber 13 . This is the resting position of the device illustrated in FIG. 1 . Installed in the central area of the transverse wall 19 of the inlet fitting 3 is a flow-limiting means 10 , which in turn is located between the intake chamber 5 and the intermediate chamber 16 . This permanently prevents the passage of a flow, which however cannot exceed a threshold value that is determined through the characteristics of the flow-limiting means, from the intake chamber 5 to the intermediate chamber 16 and then from there to the outlet chamber 7 and to the outflow passage 6 . Because a thermostatic mixer serves to stabilize, a flow-limiting means 10 is selected so that the flow limit it defines corresponds to the maximum value of the flow that is able to cause the oscillation of the thermostatic mixer concerned. In the resting position illustrated in FIG. 1 , the entire device can be penetrated by a flow, which is limited by the flow-limiting means 10 . If a flow limited in this way is present, the inlet pressure is present in the intake chamber 5 and in the inlet chamber 13 , the pressure in the intermediate chamber 16 is negligibly smaller than the inlet pressure due to the drop in pressure sustained by the flow as a result of crossing through the flow-limiting means 10 , and the pressure in the outlet chamber 7 is further reduced due to the drop in pressure sustained by the flow as a result of crossing through the limited passage 12 . Through the difference between the pressure prevailing in the intermediate chamber 16 and the smaller pressure prevailing in the outlet chamber 7 , the piston is acted upon to the effect that it moves away from the inlet fitting 3 , while the spring 17 works against this process. In contrast to this, the piston is practically not influenced by the inlet pressure present in the inlet chamber, since this pressure acts radially. On the other hand, the drops in pressure sustained by the flow depend only on the intensity of the flow and the resistances placed against it and not on the absolute value of the pressure. The behavior of the piston in turn is not influenced by the inlet pressure value and changes therein. The limited axial passage 12 and the return spring 17 must be proportioned relative to one another so that the effect of the spring 17 is essentially equal to the force acting to displace the piston out of the first position and into the second position, when the maximum flow allowed by the flow-limiting means 10 is discharged. The piston in turn holds its first position illustrated in FIG. 1 as long as the demanded flow remains below the nominal maximum value. If, however, a flow is demanded from the outlet fitting 4 that is greater than the maximum defined above, the pressure in the outlet chamber 7 drops, and the differential pressure acting on the piston 8 exceeds the force of the return spring 17 . The piston 8 is then displaced into its second, opening position illustrated in FIG. 2 . The shell section 9 ceases to interrupt the passage between the inlet chamber 13 and the intermediate chamber 16 , and the passage of the flow from the inlet chamber 13 to the outlet chamber 7 is essentially allowed. If the demanded flow is later reduced once again or completely shut off, the effect of the return spring 17 again exceeds the pressure differential acting on the piston 8 , which moves back into its first closing position illustrated in FIG. 1 . In FIG. 3 through 8 , which show other embodiments of the invention, the parts that are identical to or correspond to the parts of the first embodiment are labeled with the same reference numbers. In the embodiment described until now, the flow still sustains a veritable constriction owing to the reduced passage 12 of the transverse wall 11 of the piston 8 , when the piston 8 moves into its second position as a result of the passage from the inlet chamber 13 to the intermediate chamber 16 being allowed. This constriction can be eliminated in the embodiment illustrated in FIGS. 3 and 4 . In this embodiment all parts are identical to those of the embodiment illustrated in FIGS. 1 and 2 except for the fact that the passage 12 of the transverse wall 11 of the piston 8 features a significantly larger diameter so that it does not cause a damaging constriction and its cross section, when the piston 8 is in its first closed position, is reduced with the aid of a tube-shaped projection 18 , which originates from the transverse wall 19 of the inlet fitting 3 and extends into the passage 12 and in which the flow coming from the flow-limiting means 10 proceeds. As FIG. 4 makes clear, when the piston 8 is displaced into its second position, the projection 18 ceases to reduce the cross section of the passage 12 , which in turn no longer represents a constriction. FIG. 5 illustrates an embodiment that distinguishes itself from the previous embodiments in terms of construction by featuring male instead of female connection parts. This embodiment also distinguishes itself from the previous in the construction of the inlet fitting 3 , which in this example features a supplementary element 19 that is disposed between the fitting 3 and the body 1 of the device and becomes the part of the inlet fitting 3 . By means of radial passages, the supplementary element 19 defines the intake chamber 5 and forms the axial circumferential passages 2 , which open into the inlet chamber 13 . The use of the supplementary element 19 allows the construction of the inlet fitting 3 to be simplified and is especially economical if the supplementary element 19 is made of a synthetic material. FIG. 6 shows a further configuration of the embodiment illustrated in FIG. 5 . In this embodiment, the edge of the end of the shell section 9 of the piston 8 , which in the previous embodiments abuts the level surface of the inlet fitting 3 , partly engages in a seat recessed in this level surface. The advantage of this arrangement is found in the fact that if an abrupt variation of the outlet flow occurs, the piston 8 can coincidentally sustain a limited displacement that can bring it to the second opening position, even when the outlet flow has not exceeded the predetermined value for the suppression of the constriction of the passage cross section of the cold inlet water. In this case, if the piston 8 is closed by simply abutting the edge of the shell section 9 , the passage cross-section automatically opens at least temporarily. If by contrast the arrangement described using FIG. 6 is used, a limited coincidental displacement of the piston 8 is modified so that the edge of the shell section 9 is not brought outside the seat provided in the inlet fitting, the state of constricting the passage cross-section does not appear [MD 1 ] and provides no reason for problems. The same principle, which was explained using FIG. 6 , finds another use in the form of the embodiment illustrated in FIGS. 7 and 8 . In this case, the partial transition between the shell 9 of the piston 8 and a part of the supplementary element 19 that is part of the inlet fitting 3 is accomplished by pressing a projection 29 of the element 19 into the inside of the shell 9 . The projection 29 is provided with a ring seal, which in the state of axial compression is arranged in a seat. This seal slightly slows down the movement of the piston 8 to prevent the accidental displacement thereof, and also compensates the tolerances of the parts with regard to their coaxiality, thus facilitating a simpler and more economical manufacturing process. FIGS. 7 and 8 also show that a smaller gap 28 is provided between the piston 8 and the body 1 of the device. When the piston 8 is in a resting position, this gap facilitates the passage of a reduced flow in addition to the flow allowed by the flow-limiting means 10 without requiring a modification of the function of the device, which is projected taking into consideration this flow as well. The presence of this gap makes it possible to manufacture parts with greater tolerances and thereby at reduced cost. FIGS. 9 and 10 illustrate, in a resting state and in a state with a large flow, respectively, a stopcock containing a device for dynamically controlling the flow as shown in FIG. 6 . In this case, a half of the body 20 [MD 2 ], which is illustrated in the figures above, is essentially equivalent in terms of form and parts contained to the upper portion of the device illustrated in FIG. 6 , while the bottom portion of the body 20 contains a normal closure element 21 of a stopcock, the seal 22 of which acts against the transverse wall 14 intersected by the passage 15 . In this example, a side of the body 20 features the outlet fitting 4 with the outflow passage 6 . This results in a compact component with dimensions that are only slightly greater than those of a normal stopcock and that facilitates a simplification of the system by having only one component, rather than two, installed in series with a thermostatic mixer. Furthermore, in this embodiment the supplementary element 19 , which is a part of the inlet fitting 3 , is elongated, resulting in a cylinder 23 being formed in which the piston 8 runs. The inlet chamber 13 is formed by openings formed in this cylinder 23 . It must be established that the different modifications of parts of the device, which were described in reference to specific embodiments, can in general be used in the other embodiments as well. As the previous paragraphs state, the invention facilitates the realization of a device for the dynamic control of a water flow that is practically immune to variations in the inlet pressure of cold water, the flow of which it regulates for the purpose of sending it to a thermostatic mixer to stabilize the mode of functioning thereof. As a result, it is no longer necessary to adjust the load of the return spring in relation to the inlet pressure present in the system, and absolutely no defect in the functioning of the device is to be observed if, for any reason, this inlet pressure changes to a major degree. Through the simple step of suitably proportioning its parts, it is possible to realize the device so that it satisfies various demands of the installation. Furthermore, the simplicity and limited dimensions of the device allow it to be fitted into a stopcock should it be deemed necessary. It must be established that the invention is not limited to the embodiments described and illustrated as examples. The most diverse modifications have been described with additional being within the realm of the knowledge of a person skilled in the art. These and additional modifications as well as any substitution with technical equivalents can be added to the described and illustrated embodiments without representing a departure from the protective scope of the invention and this patent.	The disclosure relates to a device for dynamic adjustment of a water flow, used to stabilize the operational mode of a thermostatic mixing tap. The inventive device includes a valve consisting of a piston and a return spring forcing the piston into a first position, said piston being displaced into two positions according to the flow. When the flow is lower than a threshold value, the piston is located in the first position and a flow limited means limits the flow. When the flow exceeds the threshold value, the piston is displaced into the second position and the flow limiting means is obviated.	8
CROSS REFERENCE TO RELATED APPLICATIONS This application is related to the commonly owned co-pending U.S. patent applications entitled “System and Method for Locating Documents a User has Previously Accessed,” U.S. patent application Ser. No. 10/910,607, filed Aug. 4, 2004, “System and Method for Utilizing a Desktop Integration Module to Collect User Metrics,” U.S. patent application Ser. No. 10/910,606, filed Aug. 4, 2004; “System and Method for Presenting Multi-Variable Dynamic Search Results Visualizations,” U.S. patent application Ser. No. 10/910,568, filed Aug. 4, 2004; “System and Method for Providing a Result Set Visualization of Chronological Document Use,” U.S. patent application Ser. No. 10/910,641, filed Aug. 4, 2004; “System and Method for Providing Graphical Representations of Search Results in Multiple Related Histograms,” U.S. patent application Ser. No. 10/910,617, filed Aug. 4, 2004; “System and Method for Enhancing Keyword Relevance by User's Interest in the Search Result Document,” U.S. patent application Ser. No. 10/910,577, filed Aug. 4, 2004; “System and Method for Automatically Searching for Documents Related to Calendar and Email Entries,” U.S. patent application Ser. No. 10/910,604, filed Aug. 4, 2004; and “System and Method for Remotely Searching a Local User Index,” U.S. patent application Ser. No. 10/910,640, filed Aug. 4, 2004, each filed herewith and incorporated by reference in its entirety. FIELD OF THE INVENTION The invention relates to an application for searching a document that a user has previously viewed on user terminal device. BACKGROUND OF THE INVENTION Many programs enable a user to search for documents located on the computer device. For example, a user may be able to search for a document by entering search terms believed to reflect the document's title or by entering search terms believed to be included in the document text. However, conventional document management tools are limited in the amount of search criteria that a user may use to locate a particular desired document. Often, users only remember, or have access to, small bits of information related to the document for which they are searching, such as, for example, the day and/or approximate time the document was accessed, a broad overview of what the document was about, and/or other details. Users are generally not good at creating search criteria, particularly based on such limited information, and would be better at modifying a search if they were give clues to form a more effective search. It is an aspect of the invention to assist a user with searching specifically for documents the user has previously accessed by providing criteria that might enable the user to more easily locate a particular desired document. It is another aspect of the invention to provide a graphical user interface with various features and functions to facilitate the user with locating the document once the search has been performed. SUMMARY OF THE INVENTION These and other objects are addressed through various embodiments of the invention. According to one aspect of the invention, a system and method are provided for quickly and efficiently searching for and selectively retrieving one or more documents that a user has previously accessed. The previously accessed documents may or may not be located at the user's local workstation. As used herein, the term documents may refer to files such as, for example, Microsoft Word or Excel documents, email messages, web pages, media files, folders, and/or other files. The system may include a desktop integration module, an index module, a graphical user interface module, and/or other modules. The desktop integration module may monitor documents with which the user interacts for predetermined events and obtain content data and metadata from the monitored documents. The index module may index the content data and metadata received from the desktop integration module. The graphical user interface module may then permit a user to utilize the index module by allowing a user to search for documents. The desktop integration module may monitor documents that the user views, edits, creates, or otherwise accesses for predetermined events. For example, the desktop integration module may track each time a user opens a document and each time the user closes the same document, enabling the duration of document interaction to be determined. The desktop integration module may obtain content data, such as keywords, title of the document, author of the document, and/or other control data and metadata determined from the predetermined events for the monitored documents, and transfer the content data and metadata to the index module. The index module may index parameters that enable the user to search and filter the monitored documents. For each document monitored by the desktop integration module, the index may include parameters such as, for example, the date created, the date opened, the date closed, the date modified, the amount of time spent on a document, the date printed, the date sent, the number of times of document was accessed, and/or other parameters. The index module may also store keywords from the document, the title of the document, and/or the author of the document. These parameters in the index module may be determined from the content data and metadata collected by the desktop integration module. A filter may be provided, enabling user to specify documents that are not to be indexed, such as a default home page or personal email. The graphical user interface module may enable a user to perform searches of the index created by the index module and therefore locate a document which has been previously accessed by the user. The results reflect documents considered relevant in content based on the search terms and other parameters entered by the user such as, for example, dates and selected applications. The user may browse the search results and/or sort the result set by various criteria for ease of viewing. According to one aspect of the invention, desktop integration module may include one or more subsystems, such as, for example, application plug-ins, a communications module, a user interaction module, a document filter module, and/or other modules. The desktop integration module may track each instance in which a user enters a URL to access a web page. In some embodiments, the desktop integration module may track web pages that a user visits by accessing a link on a page for which a URL was entered. In other embodiments, the desktop integration module may track an instance where the user opens a Word document or reads an email. A document filter module may be provided to enable a user to specify documents that should not be monitored or indexed. For example, documents that a user commonly accesses or documents that contain private information such as, for example, online bank account statements or webpages with the “https” protocol may be filtered and not indexed. Application plugins may extract information from documents such as, for example, document type, content, and/or author. Communications module may be used to queue documents being retrieved from application plugins to the index module. Communications module may also convert documents from their native format, such as, for example, .DOC or .XLS, to a common XML format. User interaction module may interact with application plugins to track the amount of time a user spends interacting with a document. According to another aspect of the invention, the graphical user interface module may present a graphical user interface having multiple graphical visualizations of a search results set. A calendar may be displayed indicating when a user has accessed a document in the search results set. A document usage histogram may be displayed illustrating all documents that the user has accessed compared to those documents matching the search query. According to another aspect of the invention, a histogram displayed on a graphical user interface may allow a user to see the context of the result set against their own document usage. Vertical lines may be presented indicating documents that match the search query. The vertical lines may be of varying heights, indicating the relevance of the document to the search query. According to another aspect of the invention, multiple related histograms may be provided. The histograms may represent the relevance of the search results, as well as the number of documents matching the search criteria for a given day. The histogram may have one axis displaying, for example, dates and times, and another axis displaying, for example, the amount of time spent on a particular document. According to another aspect of the invention, better search results for specific users may be returned by enhancing the result set rankings according to a specific user's interest in the document. User metrics may be collected during a user's interaction with other documents to enhance keyword relevance rankings. User metrics may include the time spent on a document, frequency with which the document was viewed, whether the document is printed, and/or other metrics. The amount of time a user has spent on a document may be measured if one or more criteria such as, for example, whether the document is in focus and/or whether some type of input has been received relative to the document within a particular time interval, are met. According to another aspect of the invention, historical data related to a user's interaction with a document may be provided with a search results set. This may allow a user to more readily distinguish between documents in the results set. A user may view metrics obtained by the desktop integration module by performing a triggering action, for example, by right-clicking on a document in the results set or other triggering action. Performing the triggering action may cause the calendar and histogram views to change, reflecting the additional information. According to one aspect of the invention, the search system may be embedded into a user's calendar and/or email application. The user may then generate search queries by performing a triggering action on a selected calendar or email entry. The search query may include, for example, the title of a meeting, meeting attendees, dates, keywords in the body of the calendar or email entry, and/or other query options. According to another aspect of the invention, a system and method may be provided, enabling users to search a local workstation from an enterprise portal. This may enable the user to search their local workstation as well as other document management systems simultaneously. An index control program and a web responder may be downloaded to a user's workstation. Documents may then be indexed at the user workstation and inbound query requests by an enterprise portal server may be accepted. A user may perform a search of their workstation through an enterprise portal. The search query may be processed at the local workstation and results may be returned in a format compatible with the enterprise server. Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. The drawings are designed for purposes of illustration only and the invention is not limited to the particulars shown therein. Various alternatives and modifications within the scope of the invention will be apparent from the description contained herein. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a system for searching for previously accessed documents, according to an embodiment of the invention. FIG. 2 illustrates a graphical user interface, according to an embodiment of the invention. FIG. 3 illustrates a web portal having an embedded search field, according to an embodiment of the invention. FIG. 4 is a flowchart illustrating an operation of a desktop integration module, according to an embodiment of the invention. FIG. 5 illustrates a graphical user interface, according to one embodiment of the invention. FIG. 6 illustrates a chronology histogram, according to an embodiment of the invention. FIG. 7 illustrates another chronology histogram, according to an embodiment of the invention. FIG. 8 illustrates a graphical user interface, according to an embodiment of the invention. FIG. 9 illustrates a graphical user interface, according to an embodiment of the invention. FIG. 10 illustrates a results set listing, according to an embodiment of the invention. FIG. 11 illustrates a calendar view from an email program, according to an embodiment of the invention. FIG. 12 is a block diagram of a system for searching from a remote portal, according to an embodiment of the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS According to one embodiment of the invention, a system 100 may be provided enabling a user to search for and/or selectively retrieve documents that the user has previously accessed. FIG. 1 is a block diagram of system 100 , according to an embodiment of the invention. A search agent 102 may be provided. Search agent 102 may include one or more modules such as, for example, a desktop integration module 104 , an index module 106 , a graphical user interface module 108 , and/or other modules. Search agent 102 may be located at a user terminal 110 . In some embodiments, certain modules such as, for example, index module 104 may be implemented at user terminal 110 , while other modules may be implemented at user terminal 110 or remotely. Other variations may be used, as would be apparent. User terminal 110 may include any one or more of, for example, a desktop computer, a laptop or other portable computer, a hand-held computer device such as a Blackberry, a Personal Digital Assistant (PDA), and/or any other terminal device. User terminal device 110 may be connected to an enterprise portal server 112 over a network 114 via a communications link 116 . Server 112 may enable a user to remotely search for documents the user has accessed, even if these documents are stored at the user's terminal device. Server 112 may be or include, for example, a workstation running Microsoft Windows™ NT™, Unix, Linux, Novell Netware™, and/or other operating systems. Network 114 may include any one or more networks, such as, for example, the Internet, an intranet, a Local Area Network (LAN), and/or other networks. Communications link 116 may include any one or more communications links such as, for example, a copper telephone line, a Digital Subscriber Line (DSL) connection, an Ethernet connection, an Integrated Services Digital Network (ISDN) line, a wireless connection, or other communications link. Desktop integration module 104 may be provided to monitor documents accessed by a user for predetermined events. Desktop integration module 104 may monitor any document that the user views, edits, creates, prints, downloads, or otherwise accesses. These predetermined events may be or include, for example, opening a document, closing a document, printing a document, emailing a document, and/or other predetermined events. Index module 106 may receive data from desktop integration module 104 and put the data into a format that may be searched by a user using a graphical user interface. Index module 106 may enable a user to filter search results by, for example, a date or date range, a document type, and/or other parameters. A user may specify certain documents that should not be indexed, such as, for example, a default homepage or a search index. Graphical user interface module 108 may provide a graphical user interface (GUI) that enables a user to search for a previously accessed document. A user may initiate a query from a search portlet located on the user's portal page by using a traditional keyword search terms. The portal software may then direct the query to index module 106 and search results may be presented to the user in a new graphical user interface. A graphical user interface for displaying search results and modifying a search is described in detail hereinafter. FIG. 2 illustrates an example of a portal page 200 having a search portlet 202 embedded therein. If a user enters a keyword search into search portlet 202 and does not have the system software for searching the local index stores on their workstation, the software may automatically be downloaded from server 112 . The user may be presented with a dialog box where the user may be asked if they would like to install the system. Once the user has consented to install the components, the index and a control program are downloaded and installed. Once installed, the program may begin to create an index of documents the user has accessed by searching well known browser caches for web documents and/or intercepting calls to known productivity applications. A desktop integration module may monitor predetermined events by retrieving content data and metadata from the applications used to access the documents. Metadata may refer to data describing an action taken by the user such as, for example, choosing a “document open” or a “document close” action. Metadata may also indicate the date and/or time a document was accessed. Content data may include data such as, for example, words found in the document, keywords stored with the document, a name of the document, an author of the document, and/or other content data. In some embodiments, keywords may be specified by the user when creating or modifying a document. In some embodiments, keywords may be determined by desktop integration module 104 based on the frequency of occurrence of certain words in the document. According to one embodiment of the invention, desktop integration module may include one or more subsystems. FIG. 3 illustrates desktop integration module 300 , according to an embodiment of the invention. Desktop integration module 300 may include one or more modules such as, for example, an applications plugin module 302 , a communications module 304 , a user interaction module 306 , a document filter module 308 , and/or other modules. Application plugin module 302 may include one or more stand alone modules which may be instantiated when an application matching a specified type is started by the user or an operating system at the user's terminal. Application plugin module 302 may extract information from documents such as, for example, the document type, content as text, author, size, creation date, and/or other document information. Application module 302 may also collect information related to a user's access of or interaction with a document, such as, for example, whether a user forwards an email or other document, edits a document, prints a document, and/or other user access. Application plugin module 302 may be connected to communications module 304 through a standard plugin interface. Communications module 304 may submit documents being retrieved from application plugin module 302 to index module 106 , enabling the documents to later be searched. Communications module 304 may convert documents into a format that can be readily indexed, such as, for example, from a binary .DOC format to a XML format. User interaction module 306 may monitor an amount of time a document is accessed by the user. In some embodiments of the invention, user interaction module 306 may be integrated with the operating system used at the user's terminal to track the duration of a user's access of a document. For example, in a Microsoft Windows operating environment, Windows application programming interfaces, which may register file open and close operation, may be used to track the duration of a user's access of a document. In some embodiments of the invention, some documents need not be tracked and indexed by the system. Document filters module 308 may be used to filter out documents that should not be tracked by the system. A user may define filters based on a number of factors such as, for example, document type, uniform resource identifiers (URIs), and/or other factors. For example, documents in the Microsoft Money application format may have personal financial information, so a user may wish to define a filter for excluding these documents from the index. Documents having URIs known to contain personal information such as, for example, “c:\Document Settings\User\Personal”, or documents having URIs beginning with “https:\\” may be omitted. A user may also define filters for documents that are commonly accessed, such as a default browser homepage, or a search engine such as Google. Plugin specific filters may also be defined for omitting documents, such as emails from certain addresses, from being indexed. FIG. 4 illustrates an example of the operation of desktop integration module 300 . At an operation 402 , an application, such as, for example, Internet Explorer, may be started by a user. The user may click on the Internet Explorer icon to start up the browser. At an operation 404 , an application plugin specific for Internet Explorer may start up. The application plugin may search for a communications module, or start a new singleton process, at an operation 406 . At an operation 408 , the browser may open up to a default homepage. The application plugin would then perform a filter check on the homepage URI to determine if the homepage is one that should not be indexed, as illustrated at an operation 410 . As illustrated at an operation 412 , if a filter has been set up for the current URI, no information is gathered, and no index entry is created. If no filter has been set up for the URI, an application plugin session may be created to track user activity, as illustrated at an operation 414 . At an operation 416 , user activity information may be collected and submitted to an index module. According to one embodiment of the invention, graphical user interface module 108 may provide a graphical user interface for displaying search results and enabling a user to enter additional search criteria. FIG. 5 illustrates a graphical user interface 500 , according to one embodiment of the invention. Following an initial keyword search execution via portlet 202 , GUI 500 may be presented having results set 502 . Results displayed in results set 502 may be sorted in various ways such as, for example, by relevance, document type, alphabetically, chronologically, and/or other sorting methods. Sorting menu 504 may be provided, enabling a user to select a desired sorting method. A user may choose to view only documents of a certain type by selecting one or more document type filters 506 . Additional keywords may be entered or a new search may be executed by entering search terms into query box 508 . Selecting recall button 510 may enable a search to be performed of all documents the user has previously accessed matching the search criteria. In addition to standard search results displayed in search results box 502 , various graphical visualizations may be provided. A calendar 512 may be provided. Calendar 512 may include indicia 514 indicating days on which documents from the search result set have been accessed. Indicia 514 may indicate the first time a user has accessed a document, or in other embodiments may indicate each access by the user. As illustrated in FIG. 5 , indicia 514 may include highlighting a particular calendar day or days. Other visual indicators may be used, as would be apparent. A user may restrict results displayed in search results box 502 by selecting one or more dates from calendar 512 . Results box 502 entries may then be limited to documents which have been accessed on the selected dates. A histogram 516 may be provided for controlling the result set in a similar manner to calendar 512 . A user may select either end of bounding box 518 to dynamically revise the result set, showing only those results within the selected date range. Histogram 516 may illustrate documents matching the search query in addition to all documents accessed by the user, allowing the user to see which documents were used within which sequence. For example, dark colored vertical lines 520 a may indicate documents that match the search criteria, while light colored vertical lines 520 b may indicate all other documents the user has accessed. Other visual indications may be used, as would be apparent. According to an embodiment of the invention, a user may retrieve a chronological display of document usage. FIG. 6 illustrates a chronology histogram 600 , according to this embodiment of the invention. Chronology histogram 600 may be provided wherein both results set documents and other used documents are shown as vertical bars on a horizontal timeline. Horizontal timeline 602 provides a date range for which chronology information may be obtained. This date range may be extended by selecting and dragging the ends of bounding box 604 outward. The date range may also be contracted by dragging the ends of bounding box 604 inward. In addition to the timeline on the horizontal axis, the height of each bar may provide additional information to the user about a document. The height of vertical lines may indicate the relevance of each document to the search query. In an alternative embodiment, the height of the vertical lines may indicate a specific usage pattern such as, for example, the amount of time spent working in a specific document. A user's usage activity may be recorded by Desktop Integration Module (shown in FIG. 1 ) and this information may be normalized to display a usage summary on chronology histogram 600 . Selecting a vertical line may open the selected document directly. In other embodiments, selecting a vertical line may cause a popup window 606 to be displayed. Pop-up window 606 may display a result set summary for the selected document. Summary information displayed in popup window 606 may include, for example, the document name, document location, document type, a summary of the document content, and/or other document related information. According to one aspect of the invention, multiple variables may be characterized on the vertical axis of a chronology histogram. FIG. 7 illustrates a chronology histogram 700 , according to this embodiment of the invention. Displaying multiple variables may enable a user to quickly and efficiently locate a desire document. As illustrated, chronology histogram 700 displays both relevance of search results documents to the entered keywords as well as the amount of time spent accessing or interacting with the document. Other document characteristics may be displayed such as, for example, the number of hits. Vertical axis 701 may provide multiple variables such as, for example, a relevance variable 702 and a duration variable 703 . White boxes 704 may be provided to illustrate the time a user has spent on a document. This time may be illustrated for all documents a user has accessed, whether or not a particular document matches the search criteria. Shaded boxes 706 may indicate the relevance of one or more documents matching the criteria. Horizontal axis 708 may indicate one or more dates a document was accessed. Horizontal axis 708 may also indicate, chronologically, the order in which a document was accessed. In some embodiments of the invention, horizontal axis 708 may provide a time display, indicating the time interval in which a document was accessed. According to one aspect of the invention, relevance calculations for search results are enhanced for a specific user by collecting user metrics during the user's interaction with the document. In addition to ranking documents based on the frequency and location of keyword hits and the proximity of query keyword hits to each other, the invention may collect metadata using desktop integration module 104 (illustrated in FIG. 1 ). Collected metadata may include, for example, the amount of time spent on a document, how often a document has been viewed, or otherwise accessed, whether or not the document was printed or emailed, and/or other document related actions. Certain criteria may be required in order to determine the amount of time a user has spent interacting with a document. For example, it may be a requirement that the user has the document open and in focus. In focus may refer to having the selected document as the active window when multiple documents and/or applications are open. A user may be required to perform some type of input/output operation within a predetermined time interval in order for time calculation to continue. For example, the input/output operation may be a keystroke or mouse movement. Once the criteria have been satisfied, the collected metadata may be entered into the index using index module 106 (illustrated in FIG. 1 ). Opening a document multiple times may cause metadata to be obtained for both frequency and duration of use. For example, a document that has been opened three times may show a frequency of three, and the total amount of time spent among the three accesses may be combined to calculate the amount of time the user has spent on the document. According to another aspect of the invention, metrics regarding a user's interaction with one or more documents may be presented to the user on a graphical user interface. Presenting user metrics to the user may enable the user to more readily distinguish between documents in the result set and simplify the process of finding the desired document. In some embodiments of the invention, a user may trigger the user interface to present user metrics by performing an action such as, for example, right-clicking on the document in the result set. A pop-up window 802 may be provided, as illustrated in FIG. 8 . Pop-up window 802 may display, for example, document name, document location, the number of times the document has been opened by the user, the total amount of time the user has spent on the document, and/or other user metrics. In some embodiments of the invention, user metrics may be displayed when a user hovers over a document in the result set. Hovering over a document may cause a change in the calendar and/or histogram graphical representations. For example, as illustrated in FIG. 9 , calendar 902 may highlight days on which the selected document has been accessed. Histogram 904 may provide additional user metrics. For example, the x-axis of histogram 904 may display the dates in which the user accessed the selected document, while the y-axis illustrates the amount of time the user spent on the document. Small icons, such as icons 906 , may be presented on histogram 904 , indicating the amount of time the user spent on the document. Other icons may also be presented, for example, a printer icon, book icon, and/or envelope icon may be presented to indicate that the user has printed, read, and/or emailed the document, respectively. Other icons may be presented indicating editing of a document, forwarding, replying, and/or other document related actions, as would be apparent. While certain actions have been described above, other actions may be used to present user metrics to the user. For example, a user may single click on a document to change the views of the histogram and calendar, or the user may double click on a document to open a new window providing user statistics. According to an embodiment of the invention, user metrics may be provided directly in the results set without requiring additional actions to be performed. FIG. 10 illustrates a result set 1000 which provides user metrics. User metrics illustrated in result set 1000 may include, for example, the total viewing time for each document, the amount of time the document was viewed, and the date the document was last accessed. Other user metrics may be provided, as would be apparent. According to another aspect of the invention, the system may be integrated into a user's email and calendar application. A user may quickly obtain documents relevant to a particular email message or calendar entry. A user interface for searching based on a user's email and calendar entries may be integrated with the email applications in some embodiments, or may be a standalone application. FIG. 11 illustrates an example of a calendar view 1100 associated with an email program such as, for example, Lotus Notes. As illustrated, several meetings 1110 are listed on calendar 1100 . A user wishing to view documents related to a scheduled meeting may do so by selecting the meeting and choosing an option to search for related documents. Options may be provided by various ways, such as, for example, “right-clicking” on a meeting to bring up a pop-up menu, choosing an option from Actions menu 1112 , or other methods as would be apparent. Search criteria may also be created from an email message. Search criteria may include, for example, the title of the meeting, subject of the email message, keywords from the body of an email message, names of meeting invitees, and/or other criteria. Desktop integration module 102 may obtain content and metadata from calendar 1100 regarding the selected meeting. Indexing module 104 may use the retrieved metadata and content data and compare it to the indexed data for all stored documents. Documents having matching content data and/or metadata may be returned as being related to the selected meeting. In other embodiments, authors of documents may associate the document with certain meetings. In some embodiments of the invention, only documents accessed on the day of the meeting are retrieved while in other embodiments, all accessed documents related to the meeting are returned. Once the user has been presented with search results, the user may modify the search to more quickly find desired documents. For example, the user may input additional keywords, use document type filters to return only documents of certain types, restrict the search to one or more dates, and/or other search modifications. According to another aspect of the invention, a system may be provided, enabling a user to search a local workstation from a remote portal location. As used herein, local workstation may refer to the workstation that is assigned to a particular user and from which the user typically works. A user may have access to documents stored on their local device and may be able to integrate these documents into a portal integration environment. As described above, in some embodiments of the invention, an index and control program may be downloaded to a user's workstation the first time a query is made using the portlet. In addition to the index and control programs, a web responder may also be installed. FIG. 12 illustrates a block diagram 1200 of the system including web responder 1202 . In some embodiments of the invention, web responder 1202 listens for inbound queries from Enterprise Portal Server 1204 over network 1206 . Once web responder 1202 has been installed, queries from Enterprise Portal Server 1204 may be accepted at user terminal 1210 . A user may perform a search from Enterprise Portal Server 1204 in a manner similar to performing a local search. The user may enter a search query into a portal page, such as the portal illustrated in FIG. 2 . The query may then be sent to the local workstation where the web responder has been installed. An index at user terminal 1210 may then process the query and return the results in a format supported by Enterprise Portal Server 1204 , such as, for example, the XML format. Results may then be formatted and presented to the user. According to one embodiment of the invention, searching a local workstation index may be performed as a part of a search from another application. For example, a single search may be used to search a user's workstation, email documents, and/or a corporate document management system using a search engine integrated with the document management system. Search results may be combined into one display. In an alternative embodiment, only the user's own documents are searched using the index at the user's workstation. While particular embodiments of the invention have been described, it is to be understood that modifications will be apparent to those skilled in the art without departing from the spirit of the invention. The scope of the invention is not limited to the specific embodiments described herein. Other embodiments, uses and advantages of the invention will be apparent to those skilled in art from consideration of the specification and practice of the invention disclosed herein. The specification should be considered exemplary only, and the scope of the invention is accordingly intended to be limited by the following claims.	A method is provided for enabling a user to search for documents that the user has previously viewed on its local machine. The method includes maintaining, on a workstation of a user, an index that includes one or more entries for only one or more documents the user has previously accessed; receiving from the user a request to search the index; and presenting a user interface providing a search results listing and one or more graphical visualizations characterizing the search results. In response to an input from the user, usage metrics for a selected documents are displayed.	6
This application is a division of Ser. No. 09/359,311 filed Jul. 23, 1999 U.S. Pat. No. 6,234,275 which is a continuation of PCT/FI98/00056 filed Jan. 22, 1998. BACKGROUND OF THE INVENTION The present invention relates to elevator drive machines and more specifically to an elevator drive machine having a rotating traction sheave between rotors of multiple motors along the axis of rotation. The drive machine of a traction sheave elevator has a traction sheave with grooves for the hoisting ropes of the elevator and an electric motor driving the traction sheave either directly or via a transmission. Traditionally the electric motor used to drive an elevator has been a d.c. motor, but increasingly a.c. motors, such as squirrel-cage motors with electronic control are being used. One of the problems encountered in gearless elevator machines of conventional construction has been their large size and weight. Such motors take up considerable space and are difficult to transport to the site and to install. In elevator groups consisting of large elevators, it has sometimes even been necessary to install the hoisting machines of adjacent elevators on different floors to provide enough room for them above the elevator shafts placed side by side. In large elevator machines, transmitting the torque from the drive motor to the traction sheave can be a problem. For example, large gearless elevators with a conventional drive shaft between the electric motor and the traction sheave are particularly susceptible to develop significant torsional vibrations due to torsion of the shaft. Recently, solutions have been presented in which the elevator motor is a synchronous motor, especially a synchronous motor with permanent magnets. For example, the specification of WO 95/00432 presents a synchronous motor with permanent magnets which has an axial air gap and in which the traction sheave is directly connected to a disc forming the rotor. Such a solution is advantageous in elevator drives with a relatively low torque requirement, e.g. a hoisting load of about 1000 kg, and in which the elevator speed is of the order of 1 m/s. Such a machine provides a special advantage in applications designed to minimize the space required for the elevator drive machine, e.g. in elevator solutions with no machine room. The specification of FI 93340 presents a solution in which the traction sheave is divided into two parts placed on opposite sides of the rotor in the direction of its axis of rotation. Placed on both sides of the rotor are also stator parts shaped in the form of a ring-like sector, separated from the rotor by air gaps. In the machine presented in the specification of FI 95687, the rotor and the stator parts on either side of it with an air gap in between are located inside the traction sheave. In this way, the traction sheave is integrated with the rotor, which is provided with magnetizing elements corresponding to each rotor part. The specification of DE 2115490 A presents a solution designed to drive a cable or rope drum or the like. This solution uses separate linear motor units acting on the rim of the drum flanges. For elevators designed for loads of several thousand kg and speeds of several meters per second, none of the solutions presented in the above-mentioned specifications is capable of developing a sufficient torque and speed of rotation. Further, problems might be encountered in the control of axial forces. In motors with multiple air gaps, further difficulties result from the divergent electrical and functional properties of the air gaps. This imposes special requirements on the electric drive of the motor to allow full-scale utilization of the motor. Special requirements generally result in a complicated system or a high price, or both. The specification of GB 2116512 A presents a geared elevator machine which has several relatively small electric motors driving a single traction sheave. In this way a machine is achieved that needs only a relatively small floor area. The machine presented in GB 2116512 A can be accommodated in a machine room space not larger than the cross-sectional area of the elevator shaft below it. Such an advantageous machine room solution has not been usable in the case of the large gearless elevators because these typically have a machine with one large motor that extends a long way sideways from the traction sheave. The specification of EP 565 893 A2 presents a gearless elevator machine comprising more than one modular motor unit, which are connected together to drive traction sheaves also connected together. In such a solution, the length of the machine increases as its capacity is increased by adding a motor module. The problem in this case is that the length of the machine is increased on one side of the traction sheave, which is why the machine extends beyond the width of the elevator shaft below. Supporting and stiffening such a long machine so that its own weight and the rope suspension will not produce harmful deformations is likely to result in expensive and difficult solutions. For instance, the bending of a long machine requires a special and expensive bearing solution. If bending or other forms of load produce even the slightest flattening of the traction sheave to an elliptical shape, this will probably lead to vibrations that reduce the traveling comfort provided by the elevator. SUMMARY OF THE INVENTION It is an object of the present invention to achieve a new gearless elevator drive machine which develops a torque, power and rotational speed preferably as needed in large and fast elevators. With the solution of the invention, the present torque is developed by means of two motors or motor blocks, the torque being thus doubled as compared with a single motor. The axial forces generated by the two motor blocks compensate each other, thus minimizing the strain on the bearings and motor shaft. With the drive machine of the invention, due to the present good torque characteristics of the machine, a large traction sheave size in relation to the size, performance and weight of the drive machine is achieved. For instance, an axle load of 40000 kg can be handled by a machine weighing below 5000 kg, even if the elevator speed is as high as 9 m/s or considerably higher. As the structure of the drive machine allows large rotor and stator diameters in relation to the traction sheave diameter, a sufficient torque on the traction sheave is easily generated. On the other hand, a short distance between the bearings in the direction of the axis of rotation automatically ensures small radial deflections, so that no heavy structures are needed to prevent such deflections. Especially in the case of elevator drive machines with the highest requirements regarding load capacity, having a single traction sheave driven by at least two motors helps obviate the relatively high costs in relation to load capacity of large individual motors. By placing the traction sheave between two motors, a compact machine structure is achieved, as well as a possibility to transmit the torque, power and forces directly from the machine to the traction sheave without a separate drive shaft. By coupling the rotors of two different electric motors mechanically together with the tractions sheave, these advantages are achieved to a distinct degree. The very close integration of the rotor parts of the motor with the traction sheave results in a machine in which the rotation parts practically function as a single block, allowing improved accuracy in the control of elevator movements. As the frame of the drive machine is used both as a shell of the motor/motors and as a carrier of the bearings of the moving parts, the total weight of and the space required by the machine are relatively low as compared with conventional hoisting machines designed for corresponding use. In principle, bearings are only needed for each rotor, whose bearing boxes are easy to seal. Any lubricant that may pass through the sealing can easily be so guided off that it will cause no harm. Because the traction sheave is attached substantially to the junction between the rotor blocks or because the traction sheave joins the rotor blocks together along a circle of a fairly large radius, the torque developed by the motor is transmitted directly from the rotor to the traction sheave. In the drive machine of the invention, the air gaps can be adjusted in pairs so that they will be of equal size, and the mutual air gap sizes of the two motors/motor blocks can even be adjusted so that the motors/motor blocks will look the same to the electric drive. In this way it is possible to have two motors/motor blocks driven by a single electric drive without incurring differences in the behavior of the motors/motor blocks due to the drive machine being driven by a single electric drive. Due to its small size and light weight with regard to its load capacity, the machine is easy to implement as in terms of both machine room layout and installation. Elevator machines with a high load capacity are often used in elevator groups comprising several elevators. As the hoisting machine can be accommodated in a machine room floor area the size of the cross-section of the elevator shaft below it, this provides a great advantage in respect of utilization of building space. BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention will be described by the aid of an example, which in itself does not constitute a limitation of the range of application of the invention, and by referring to the attached drawings, in which FIG. 1 presents an elevator drive machine as provided by the invention, seen from the present axial direction; FIG. 2 presents the drive machine of FIG. 1 in side view and partially sectioned; FIG. 3 presents a more detailed view of the drive machine shown in FIG. 2; FIG. 4 presents the drive machine of FIG. 1 in top view; FIG. 5 illustrates the placement of the drive machine of the present invention. FIG. 6 presents a cross-section of another drive machine according to the present invention, and FIG. 7 presents a more detailed view of the drive machine as shown in FIG. 6 . DETAILED DESCRIPTION FIG. 1 shows a gearless drive machine 1 as provided by the present invention, seen from the axial direction. The figure shows the outline 2 a of the traction sheave 2 of the drive machine 1 to illustrate the placement of the traction sheave in relation to the frame block 3 forming part of the frame of the machine. The frame block 3 is preferably made by casting, preferably as a cast iron block. The frame block can also be manufactured e.g. by welding from pieces of steel sheet. However, a welded frame block can probably be only used in special cases, e.g. when a very large machine is to be manufactured as an individual case. Even a frame block as high as about 2 m can be advantageously made by casting if a series of several machines is to be produced. The frame block is stiffened by a finning 44 . The finning is partly annular, including one or more rings, and partly radial. The radial parts of the finning are directed from the central part of the frame block 3 towards attachment points 4 , 5 , 6 , 7 , 8 provided along the edge of the frame block and towards the mountings 10 of the operating brakes 9 of the elevator and the legs 11 of the drive machine, by which the drive machine is fixed to its base. The legs 11 are located near the attachment points 6 , 7 in the lower part of the frame block. The frame block has seats for a fan 12 and a tachometer 13 with required openings. The traction sheave bearings are behind a cover 15 . The cover is provided with a duct for the adjusting screw 16 of a device for axial positioning of the traction sheave. The cover 15 is also provided with a filling hole 42 for the addition of lubricant into the bearing space and an inspection hole or window 41 for the inspection of the amount of lubricant. FIG. 2 presents the drive machine 1 in a partially sectioned side view. FIG. 3 presents details of the drive machine shown in FIG. 2, showing the bearing arrangement more clearly. In these figures, the part to the right of the center line of the machine shows section A—A of FIG. 1, while the part to the left shows section R—R of FIG. 1 . It is largely a question of definition whether the figure represents a drive machine in which the traction sheave is placed in a motor which has a rotor and a stator divided into blocks, between the two rotor blocks 17 , 18 of the motor and attached to these or whether the figure represents two motors between which the traction sheave 2 is attached to the rotors 17 , 18 of the motors. The stators/stator blocks 19 , 20 are fixed to the frame of blocks 3 , 3 a. Air gaps are provided between the stators and rotors. The air gaps in the motors shown in the figures are so-called axial air gaps, in which the flux direction is substantially parallel to the motor axis. The stator winding is preferably a so-called slot winding. The rotor magnets 21 are preferably permanent magnets and attached to the rotors 17 , 18 by a suitable method. The magnetic flux of the rotor passes through the rotor disc 17 , 18 . Thus, the part of the rotor disc that lies under the permanent magnets acts both as a part of the magnetic circuit and as a structural member of the rotor. The permanent magnets may be of different shapes and may be divided into component magnets placed side by side or one after the other. The rotor disc is preferably manufactured by casting from cast iron. Both the rotor disc and the frame blocks are preferably shaped so that they fit together with another identical body, so that it will not be necessary to produce a part and a counterpart separately. The rotor 17 , 18 is provided with roller bearings 22 supporting it on the corresponding frame block 3 a, 3 . The roller bearings 22 support the radial forces. In very large elevators, the bearings have to carry a weight of tens of tons, because in many cases almost all of the weight of both the elevator car and the counterweight is applied via the elevator ropes and compensation ropes or chains also significantly increase the weight. Axial net forces are received by an auxiliary bearing 40 . Using an axial adjustment associated with the auxiliary bearing 40 , the rotors 17 , 18 are centered so that each stator-rotor pair will have an equal air gap. The traction sheave and the rotor blocks are attached to each other to form the rotating part of the machine supported by bearings on the frame blocks. The auxiliary bearing 40 , attached by its cage to the rotor, and the screw 16 , which engages the bearing boss and is supported by the cover 15 , act as an adjusting device in the bearing housing, designed to move the motor blocks in the axial direction. When the screw 16 is turned, it pushes or pulls the whole rotating part, depending on the turning direction. Since the rotor magnets in each rotor block tend to pull the rotating part towards the stator corresponding to the rotor in question and since the stators and rotors, respectively, are identical, the center-position can be found by turning the adjusting screw until the pushing and pulling force of the screw is practically nil. A more accurate method of finding the center position is by turning the rotating part and measuring the electromotive force obtained from the stators. When, as the rotating part is revolved, the electromotive force measured from the first stator block and that measured from the second stator block are the same, the rotating part has been successfully centered. Centered in this way, both stator-rotor pairs have very consistent drive characteristics and they can be driven by a single electric drive without one of the stator-rotor pairs being subjected to a higher load than the other. The stator 19 , 20 together with its winding is attached by means of fixing elements to the frame block 3 a, 3 , which, on the one hand, acts as a mounting that holds the stator in position and, on the other hand, as the shell structure of the motor and the drive machine as a whole. The fixing elements are preferably screws. Attached to the rotor 17 , 18 are rotor excitation devices placed opposite to the stators. The excitation devices are formed by fixing a number of permanent magnets 21 in succession to the rotor so that they form a ring. The stator 19 , 20 together with the stator windings is attached with fixing elements to the frame block 3 a, 3 , which acts both as a base for holding the stator in place and as a shell structure for the entire drive machine. The fixing elements are preferably screws. The rotor 17 , 18 is provided with rotor excitation devices have been formed by attaching to the rotor a series of permanent magnets 21 in succession so that they form a circular ring. Between the permanent magnets and the stator there is an air gap which is substantially perpendicular to the axis of rotation of the motor. The air gap may also be somewhat conical in shape, in which case the center line of the cone coincides with the axis of rotation. As seen in the direction of the axis of rotation, the traction sheave 2 and the stator 19 , 20 are placed on opposite sides of the rotor 17 , 18 . Between the frame blocks 3 a, 3 and the rotors 17 , 18 there are ring-like cavities in which the stator and the magnets are placed. The outer edges of the rotors 17 , 18 are provided with braking surfaces 23 , 24 , which are engaged by the brake shoes 25 of the brakes 9 . The rotor blocks are provided with aligning elements by means of which the permanent magnets of the first and second rotors can be positioned. The permanent magnets are mounted in an arrow pattern. The magnets can be aligned either directly opposite to each other or with a slight offset. As the rotors are of identical design, placing them in pairs opposite to each other means that while the first one is rotating forward, the second one is, as it were, rotating backward if the slot windings in the opposite stators are mounted in a mirror image arrangement. This eliminates any possible structural dependence of the operating characteristics of the motor on the direction of rotation. The rotor magnets can also be implemented with the arrow figures pointing to the same direction of rotation. The aligning elements are bolts, the number of which is preferably divisible by the number of poles and whose pitch corresponds to the pole pitch or its multiple. FIG. 4 shows the drive machine 1 in top view. The connecting pieces 5 b, 8 b on the sides of the drive machine which connect the attachment points 5 , 5 a, 8 , 8 a of opposite frame blocks are clearly visible, and so is the connecting piece 4 b on the top side of the drive machine which connects the attachment points 4 , 4 a provided in the top parts of the frame blocks. The top connecting piece 4 b is of a stronger construction than the other connecting pieces. This top connecting piece 4 b is provided with a loop 43 by which the drive machine can be hoisted. In FIG. 5, the outline of the wall of the elevator shaft 39 below the drive machine is depicted with a broken line. The drive machine is clearly inside this outline. This means a space saving in the building. As the machine is completely contained in the space directly above the elevator shaft, the machine room arrangement, the machine room arangements above an elevator bank will be simple. Even when the cross-section of the machine room is the same size and shape as the cross-section of the elevator shaft, there will be enough space left over in the machine room around the drive machine to allow all normal service and maintenance operations to be carried out. By placing the legs 11 near the lower edges of the machine, a maximum stability of the machine when mounted and fixed to its support is achieved. The legs are preferably located substantially outside the planes defined by the stator and rotor blocks. FIG. 5 illustrates the way in which the drive machine 1 is placed in the machine room 45 . The drive machine is mounted on a support 46 constructed of steel beams. Using a diverting pulley 47 , the distance between the hoisting rope 48 portions going to the elevator car and to the counterweight has been somewhat increased from the width corresponding to the diameter of the traction sheave 2 . The machine in FIG. 6 is very much like the one illustrated by FIGS. 1-4. For a practical elevator, the most important differences lie in the manner of mounting the traction sheave and in the consequent possibility of using traction sheaves of different widths (length) in the machine more freely depending on the need defined by each elevator to be installed, and in the manner of implementing the bearings and the outer end of the rotating shaft. FIG. 7 shows a clear illustration of the bearings and the output end of the rotating shaft. In the drive machine in FIG. 6, each end of the traction sheave 102 is attached to a rotor 117 , 118 . Thus, the traction sheave is placed between two rotors. In the case of an axial motor as in the present example, the most essential part of the traction sheave, i.e. the cylinder provided with rope grooves together with the rotor magnet ring attached to the traction sheave, remains entirely between two planes defined by the two air gaps perpendicular to the axis of rotation. Even if the internal structure of the motor should differ from the axial motor of the present example, it will be advantageous to place the traction-sheave between the torque generating parts. The rotors 117 , 118 are rotatably mounted with bearings on the frame blocks 103 , 103 a, in which the stators 119 , 120 are fixed in place, one in each frame block. The permanent. magnets of the rotors are fixed to the rotors 117 , 118 by a suitable method. The magnetic flux of the rotor passes via the rotor disc. Thus, the part of the rotor disc that lies under the permanent magnet acts both as a part of the magnetic circuit and as a structural member of the rotor. The rotor is supported on the frame blocks by relatively large bearing elements 122 . The large bearing size means that the bearing elements 122 can well sustain radial forces. The bearing elements, e.g. roller bearings, are of a design that allows axial motion of the machine. Such bearings are generally cheaper than bearings that prevent axial motion, and they also permit equalization of the air gaps in the stator-rotor pairs on either side of the traction sheave. The equalization adjustment is performed using a separate, relatively small auxiliary bearing 140 mounted on one of the frame blocks. The auxiliary bearing 140 also receives the axial forces between the traction sheave and the machine frame. The other frame block need not be provided with an auxiliary bearing. The auxiliary bearing 140 is fixed to a cover 191 attached to the frame block and covering the bearing space. Mounted on the cover 191 is a resolver 190 or other device for the measurement of angle and/or speed, supported by a supporter 189 . The end 188 of the rotating shaft 199 transmitting the traction sheave motion projects through the central part 192 of the cover 191 , and the resolver axle is attached to this shaft end. At the other end of the shaft of the machine, usually, no output from the rotating shaft is needed, so a simpler cover 187 closing the bearing space is sufficient at that end. On the side facing the traction sheave, the bearing spaces are closed with covers 186 . The traction sheave and the rotor parts are attached to each other to form the rotating part of the machine, supported by bearings on the frame blocks. As the traction sheave is connected to the rotor parts 117 , 118 by its rim or at least by a fixing circle of a large diameter, the rotating part can be regarded as forming the drive shaft of the machine in itself. As for practical design, the deflection of such a shaft is almost nil, so the design of the bearings of the drive shaft and its suspension on the frame blocks is a fairly simple task. The auxiliary bearing 140 and the larger bearing 122 supporting the radial forces are placed one after the other in the axial direction, which is a different solution as compared with the relative positions of the auxiliary bearing 40 and the larger bearing 22 in the machine illustrated by FIGS. 1-4, in which the auxiliary bearing 40 is located inside the larger bearing 22 . The successive placement of the bearings 122 and 140 allows a larger radial clearance in the bearing 122 supporting the radial load than the radial clearance of the auxiliary bearing 140 , because a sufficient radial flexibility can easily be achieved in the coupling between the bearings 122 and 140 . The flexibility can be increased by extending the auxiliary shaft 199 connecting the auxiliary bearing 140 to the rotor part 118 by using a mounting collar 197 to move the supporting point 198 of the auxiliary shaft inwards in the machine. Additional flexibility is achieved by providing the auxiliary shaft 199 with a waist to allow easier bending of the shaft. In this way, the smaller play of the smaller auxiliary bearing 140 can be fully utilized. Thus, the auxiliary bearing makes it possible to achieve an accurate axial position adjustment. Because of the small radial clearance, the shaft is accurately centered, which has a favorable effect on the accuracy of the resolver signal. The auxiliary bearing 140 is connected by its cage to the frame of the machine and by its center via the auxiliary shaft 199 to the rotating part formed by the traction sheave and the rotors. By adjusting the mutual positions of the auxiliary shaft and the auxiliary bearing in the axial direction of the machine, it is possible to adjust the positions of the rotors relative to the frame. The axial adjustment may be implemented e.g. by providing the auxiliary bearing and auxiliary shaft with screw threads engaging each other. It will be advantageous to adjust the air gaps between the rotors and stators of the drive machine to the same size. On the other hand, the air gaps can be adjusted until both motors/motor blocks look the same to the electric drive. In this way, the two motors/motor blocks can be driven by a single electric drive without incurring differences in the behavior of the motors/motor blocks due to the drive machine being driven by a single electric drive. The symmetrization of the motors/motor blocks across different air gaps can also be influenced by the mutual positions of the stators and rotors, especially by the angles of rotation between the stators and rotors. Several alternative methods can be used to match the motors of the double motor drive machine. When matching the motors for operation in the drive machine, the optimization can be effected by one of the following methods: i) With the motors idling, the source voltages are measured and adjusted to the same value by adjusting the air gaps and possibly also the stator angles. There are different levels in this: adjusting the amplitude of the fundamental wave, its amplitude and phase, additionally harmonics, and combinations of these. ii) With no load connected to the motors, the motors are coupled together and the air gap and possibly also the angle of the stator packets is adjusted so as to minimize the polyphase current. Here, too, it is possible to consider the fundamental wave and the harmonic wave separately. iii) With a load connected to the motors, the motors are measured and the air gaps and possibly also the stator angles are adjusted, until the currents in the two motors are equal. This is an advantageous alternative because any differences between the longitudinal impedances can also be taken into account. iv) The load is increased to the maximum and the motor currents are then equalized by adjusting the air gaps and possibly also the stator angles. Both motors will now deliver a maximum torque and the load capacity of the combination is at a maximum. In methods i) and ii), the measurements are carried out with the motor idling, thus also minimizing the energy consumption and temperature rise. Items i)-iv) can be suitably combined, e.g. by developing a cost function using suitable weighting coefficients for the compensation of maximum load capacity, energy consumption and harmonics. It is obvious to a person skilled in the art that, the embodiments of the invention are not restricted to the example described above, but that they can be varied within the scope of the following claims.	An elevator drive machine includes multiple electric motors and a traction sheave. The traction sheave is placed between the motors. With this arrangement, a higher torque is generated by the drive machine as compared to conventional solutions. Furthermore, an elevator arrangement in which such a drive is utilized exhibits efficient space utilization.	7
BACKGROUND OF INVENTION [0001] 1. Field of Invention [0002] The present invention relates to crack sealant packaging and methods of packaging crack sealant and using the same. [0003] 2. Description of Related Art [0004] “Crack sealant” is general term for materials which are used to fill and thereby seal cracks and joints in asphalt and cement pavement surfaces. Crack sealant materials are sometimes also referred to in the art by terms such as, for example: hot pour; crack seal; crack sealer; crack sealant; crack fill; crack filler; joint seal; joint sealer; joint sealant; joint fill; joint filler; rubberized asphalt; tar; polymer-modified asphalt; thermoplastic-modified asphalt; para-plastic materials; rubber-modified asphalt; traffic loop detector sealant; waterproofing membrane asphalt; modified asphalt; roofing asphalt; cold joint adhesives; marker adhesives; and other asphalt/resin/polymer compositions. Throughout the present specification and in the appended claims, the term “crack sealant” will be used exclusively, but the term should be understood to encompass all materials having the same general composition, use and/or properties. Crack sealant is widely used to fill and thereby seal cracks and joints in highways, streets, parking lots and driveways from water penetration. The use of crack sealants prolongs the service life of such pavement surfaces. [0005] Crack sealant formulations vary widely depending upon manufacturer and depending upon the particular end use application for which they are intended. In general, crack sealants are composed of base asphalt (bitumen), polymer/rubber copolymers (e.g., styrene-butadiene-styrene copolymers), extenders and reinforcing fillers. At most ambient storage and transportation temperatures, crack sealant compositions tend to be in solid form. At the time of use, crack sealants are heated to temperatures whereby they become a molten liquid and are then applied in a heated liquid form by pouring and/or pumping. The molten liquid seeps into and fills the cracks and joints and then, upon cooling, re-solidifies within the cracks and joints thereby sealing/filling same. [0006] Most crack sealant material is supplied to end users in poly bag-lined, rectangular corrugated boxes. At the time of manufacture, the corrugated box is lined with the poly bag. Molten crack sealant material is poured into the poly bag-lined corrugated box. Once the desired amount of crack sealant (e.g., 20-60 lbs.) has been poured into the poly bag lining the corrugated box, the crack sealant composition is permitted to cool, whereupon it solidifies and takes the rectangular shape defined by the interior space of the corrugated box. [0007] Packaging of this type provides certain advantages and disadvantages. Advantageously, the rectangular corrugated packages can be stacked on pallets and shipped to job sites. The corrugated packages provide a flat surface, which can bear identification information. At the time of use, the poly bags containing the crack sealant can be withdrawn from the corrugated box and inserted into the melting equipment together with the crack sealant material, with the poly bag melting and becoming part of the molten end use material. The corrugated boxes can be recycled. [0008] Disadvantageously, the corrugated boxes must be collected at the job site for recycling. In blustery conditions, the empty corrugated boxes can be blown away from their intended staging location. In wet conditions, the corrugated boxes can break down before or after the crack sealant has been used. And, the corrugated boxes are susceptible to damage (e.g., deformation) due to compression (e.g., from the weight of the material itself, when stacked). [0009] Alternative crack sealant packaging is available in the marketplace. For example, Maxwell Products Incorporated of Salt Lake City, Utah supplies crack sealant packaged within a thermoplastic container that comprises an expanded polymer (expanded polystyrene). Upon information and belief, applicant believes such packaging is described in U.S. Pat. No. 8,017,681 to Guymon et al. Packaging of this type provides certain advantages and disadvantages. The principal advantage is that the expanded polymer “shell” surrounding the crack sealant material can be inserted into the melting equipment together with the crack sealant material, with the expanded polymer melting and becoming part of the molten end use material. This means that it is no longer necessary to stage corrugated boxes at the job site for later recycling. Another advantage is that the expanded polymer “shell” is somewhat water resistant, which allows it to be stored in wet environments for short periods of time. Disadvantageously, containers of this type are relatively expensive as compared to corrugated boxes, require much more storage and transportation space (i.e., the packaging has much thicker bottom, top and sidewalls as compared to a corrugated box), and can become damaged if mishandled due to the inherent fragility of expanded polystyrene. Furthermore, due to the thickness of the containers, less crack sealant can be delivered to the melting equipment per charge. [0010] Crafco Inc. of Chandler, Ariz. markets crack sealant in meltable packaging under the PLEXI-MELT™ brand. Upon information and belief, such product consists of a rectangular block of solidified crack sealant disposed in a poly bag, which is overwrapped with and thereby enveloped within a non-woven fiber packaging film material that is the same as or similar to the non-woven polyethylene packaging material available from DuPont Industrial Packaging under the TYVEK® brand. Advantageously, the non-woven packaging film material surrounding the crack sealant material can be inserted into the melting equipment together with the crack sealant material, with the non-woven packaging film material melting and becoming part of the molten end use material. Again, this prevents the need to stage corrugated boxes at the job site. Another advantage is that the non-woven packaging film material is somewhat water resistant, which allows the product to be stored in wet environments with less concern that water will damage the container as compared to conventional corrugated box packaging. Furthermore, the wrapping is substantially thinner, by comparison, than meltable expanded polymer packaging. Disadvantageously, containers of this type are relatively expensive as compared to corrugated boxes, are somewhat difficult to handle (they are more slippery than cardboard boxes) and, the packaging material can become brittle after prolonged exposure to sunlight. [0011] There is a substantial need for improved meltable crack sealant packaging. BRIEF SUMMARY OF THE INVENTION [0012] In view of the foregoing, the present invention is directed toward meltable crack sealant packaging and methods of packaging crack sealant and using the same that overcome the limitations of the prior art. Meltable crack sealant packaging according to the present invention comprises a polymer container, which is preferably made of polypropylene, and a polymer lid, which is also preferably made of polypropylene, and which is secured to the polymer container after the polymer container has been filled with meltable crack sealant. In a preferred embodiment, the container also comprises a carry handle, which pivots from a non-operational position where the handle is disposed proximal to a sidewall of the container to an operational position where the handle is disposed above the lid. [0013] Packaging according to the invention can be melted together with the crack sealant composition contained within using conventional crack sealant heating equipment, and once melted becomes an accessory component of the applied crack sealant composition that imparts desirable properties including, but not limited to, lower surface tack, higher softening point and lower penetration. Packaging according to the invention is very rugged and can be handled during transit and/or on the job site in a rough manner without concern that the packaging will become damaged. The packaging is watertight, and can be stored outside in all weather conditions without damage to the packaging or to the crack sealant stored within. The packaging according to the invention does not take up significant volume, and provides sufficient rigidity to be self-supporting and stackable. In one embodiment, the bottom of the container is received within a depression or recess formed in the lid of the container. In another embodiment, the sidewalls preferably taper from the opening that engages with the lid toward the base, which allows the base of one container to rest within a recess formed in the lid of another container. Both configurations permit the containers to be stacked on pallets in a very stable manner, without concern that the individual containers will slide away from each other during transit or storage. [0014] The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed. BRIEF DESCRIPTION OF THE DRAWINGS [0015] FIG. 1 is a perspective view showing an upper portion of an exemplary crack sealant package according to the invention. [0016] FIG. 2 is a perspective view showing a lower portion of another exemplary crack sealant package. [0017] FIG. 3 is a section view taken vertically through the center of the exemplary crack sealant package shown in FIG. 2 . [0018] FIG. 4 is a perspective view showing fifty (50) exemplary crack sealant packages as shown in FIG. 1 disposed on a pallet. DETAILED DESCRIPTION OF THE INVENTION [0019] As noted above, FIGS. 1 and 2 are perspective views showing upper and lower portions, respectively, of exemplary crack sealant packages 10 according to the invention. In each illustrated embodiment, the meltable crack sealant package comprises a polymeric container 20 that defines a receptacle 30 having an internal volume, and a polymeric lid 40 that engages with and closes off the polymeric container to seal the volume of the receptacle in an air-tight and water-tight manner. The polymeric container preferably comprises a base portion 50 , which is preferably substantially horizontal. Sidewalls 60 extend generally upwardly from a periphery of the base portion and terminate in a rim 70 , which defines an opening. The sidewalls are preferably continuous, meaning that they do not meet in sharp corners. In both of the illustrated embodiments, the container is circular in horizontal cross section. However, it is contemplated that other shapes could be utilized, such as rectangular shapes, which preferably transition from one side of the container to another on a continuous radius (i.e., without sharp corners). Preferably, the polymeric container and the polymeric lid have a wall thickness sufficient to impart enough rigidity to allow the meltable crack sealant package to be self-supporting, and also to allow a plurality of packages of crack sealant (e.g., from about 2 to about 12, and preferably about 5 up to about 10) to be stacked atop each other without causing deformation. A wall thickness of about 100 mils or so is generally regarded as being sufficient, when the container is made of polypropylene homopolymer. [0020] With reference to FIG. 3 , a crack sealant material 80 is contained within the sealed volume of the container. The crack sealant material is a solid at temperatures up to at least 100° F., but is capable of being heated together with the container within which it is contained to an application temperature to form a molten liquid material for application to pavement surfaces to seal joints and cracks therein. [0021] In the preferred embodiment, the polymeric container comprises non-expanded polypropylene homopolymer, which provides sufficient rigidity and also impact resistance, which makes it durable. In the preferred embodiment, the reservoir is capable of containing approximately 20-40 lbs. of crack sealant material, although containers of larger or smaller size could be utilized within the scope of the invention, if desired. [0022] The crack sealant material, which generally comprises a mixture of base asphalt (bitumen), polymer/rubber copolymers (e.g., styrene-butadiene-styrene copolymers), extenders and reinforcing fillers is heated to a temperature within the range of about 200° F. to about 400° F. and mixed until all components are dissolved and/or uniformly dispersed and are in the form of a molten liquid. The temperature of the crack sealant material is reduced to a temperature below about 300° F. and then the desired quantity is poured into the reservoir. The polypropylene lid is then secured to the rim portion of the container to seal the crack sealant material therein. As illustrated in FIG. 4 , filled, sealed containers can then be stacked on a pallet for cooling, stocking and shipping. Labels can be applied to the containers before or after they are filled with the crack sealant material. Alternatively, the polymeric containers and/or the polymeric lids can be printed or otherwise marked before or after the container is filled with crack sealant material. The use of printed shrink-films and other polymeric markings is also contemplated. [0023] Preferably, the meltable crack sealant package comprises a handle 90 that is pivotally secured to the lid portion or to the polymeric container. In a preferred embodiment, the handle is selectively movable between a non-operational position (see FIG. 2 ), wherein the handle is adjacent to one of said plurality of upwardly extending rigid sidewalls, and an operational position (see FIG. 1 ), wherein said handle is above said lid portion. A handle makes it easy for an end user to lift and carry the meltable crack sealant package to the heating equipment. And the use of a handle that can be moved between a non-operational position and an operational position allows for the presence of a handle without interfering with the stackability of the packages. Alternatively, the rim of the polymeric container extends outwardly from the sidewall of the polymeric container to form a side lip 100 , which can be used to help lift and carry the packaged crack sealant material. [0024] In another preferred embodiment, an area of the opening in the polymeric container is larger than the periphery of the base portion, and the polymeric lid includes a recess 110 that is dimensioned to receive the base portion of an identical meltable crack sealant package. To facilitate this arrangement, it is possible for the sidewalls to be tapered from the opening to the base (see, e.g. FIGS. 2 and 3 ). The presence of a base-sized recess in the lid further facilitates stacking of the packages, and helps prevent individual packages from sliding off of other packages on pallets 120 during transit and/or storage (see FIG. 4 ). [0025] Meltable crack sealant packages according to the invention can be stored outdoors in the elements for at least one year in direct sunlight. During this period of exposure to the elements, the containers will not become brittle, and there is no possibility of water infiltration into the containers during this period of time. [0026] Meltable crack sealant packages can be transported to the job site on pallets (e.g., as shown in FIG. 4 ) or as individual packages. The polymeric containers are very durable, and can withstand rough treatment and other abuse. They can be hauled in an unsecured manner in the beds of pickup trucks, for example. [0027] The packages can be inserted, container and all, into conventional crack sealing application equipment such as, for example, direct fire kettles and oil jacketed applicators, which are known in the art. At the time of use, the heating equipment is turned on, and a package according to the invention is placed into the unit. The package is heated to a temperature within the range of about 350° F. to about 450° F. until the container and the crack sealant material both become molten and form a mixed molten liquid. The melted container serves as an additive that provides desirable characteristics to the crack sealant (e.g., low tack, high softening point, low penetration). The liquefied container and crack sealant material in the heating unit can then be applied to seal a joint or crack in a pavement surface by pouring or pumping in the conventional manner. [0028] Advantageously, meltable crack sealant packages according to the invention eliminate debris at the job site. There are no more corrugated boxes to be removed, collected and recycled. Furthermore, because the entire package (container and material contained therein) is placed into the heating equipment, there is a time savings because the material does not need to be removed from the packaging before use. The rugged protective polymeric packaging can be handled roughly during transit and at the job site without product loss or damage to the containers. Prior art packages are not as durable, and thus if a package is broken/pierced, the crack sealant will escape from its container and readily adhere to anything it contacts. Prior art containers that are not as durable can be damaged, which leads to a time and material expense to clean the leaked material off of surfaces where the material should not have been applied, which is difficult and messy. [0029] As noted above, the package is watertight, which means that it can be stored outside without worry of sunlight damage, molten material escaping package, water damaging the packaging etc. With reference to FIG. 3 , the inner portion of the container defines a volume that contains the crack sealant, and which cannot be infiltrated by water or other foreign material from an outer portion of the container. [0030] Corrugated containers cannot be stored where they are exposed to the elements. Containers made of expanded polystyrene are believed to exhibit some porosity, which allows for the absorption/accumulation of rainwater. And packages made of non-woven packaging materials are not watertight, require the use of adhesives, have non-rigid sidewalls that do not retain their shape in the event the product stored within becomes soft due to heat exposure, and can become brittle upon long-term exposure to ultraviolet radiation. Containers according to the present invention overcome all of these limitations. [0031] The following examples are intended only to illustrate the invention and should not be construed as imposing limitations upon the claims. EXAMPLE 1 [0032] 800 grams of an all-climate hot pour crack sealant (Dura-Fill HS available from P&T Products, Inc. of Sandusky, Ohio) was melted and then tested in accordance with ASTM Tests D 5239-09, D 36 and modified D 3121. The modifications to D 3121, which is a Standard Test for Tack of Pressure-Sensitive Adhesives by Rolling Ball, involved pouring the molten crack sealant material at a temperature of 345° F. into a metal tack test mold (3″ wide×10″ long×0.125″ deep) lined with release paper. After the crack sealant material was allowed to cool at room temperature (˜72° F.) for two hours, the track was inclined at an angle of 10°. A 7/16″ steel ball was placed atop the test track, the ball released, and allowed to roll down the track onto the solidified material. The distance of travel by the ball was measured and recorded in millimeters. Throughout the instant specification and in the appended claims the term “modified ASTM D 3121” shall refer to the ASTM D 3121 test as modified above. The testing results are reported in Table I. EXAMPLE 2 [0033] 850.8 grams of the same crack sealant used in Example 1 and 1.80 grams of poly bag material were melted together and tested using the same testing procedures as indicated in Example 1. The ratio of crack sealant material and poly bag material was intended to approximate as closely as possible the amount of poly bag material melted into the crack sealant material when the same is packaged using a conventional poly-bag lined cardboard box. The testing results are reported in Table I. EXAMPLE 3 [0034] 804.4 grams of the same crack sealant used in Example 1 and 44 grams of expanded polystyrene were melted together and tested using the same testing procedures as indicated in Example 1. The ratio of crack sealant material and expanded polystyrene was intended to approximate as closely as possible the amount of expanded polystyrene melted into the crack sealant material when the same is packaged as described in U.S. Pat. No. 8,017,681 to Guymon et al. The testing results are reported in Table I. EXAMPLE 4 [0035] 832.6 grams of the same crack sealant used in Example 1, 2.00 grams of poly bag material and 2.00 grams of Tyvek® packaging material were melted together and tested using the same testing procedures as indicated in Example 1. The ratio of crack sealant material, poly bag material and Tyvek® packaging material was intended to approximate as closely as possible the amount of such materials melted into the crack sealant material when the same is packaged as sold by Crafco Inc. of Chandler, Ariz. under the PLEXI-MELT™ brand. The testing results are reported in Table I. EXAMPLE 5 [0036] 850.0 grams of the same crack sealant used in Example 1 and 34.0 grams of polypropylene homopolymer were melted together and tested using the same testing procedures as indicated in Example 1. The ratio of crack sealant material and polypropylene homopolymer was intended to approximate as closely as possible the amount of polypropylene homopolymer that would be melted into the crack sealant material when the same is packaged according to the invention. The testing results are reported in Table I. [0000] TABLE I Ex- Ex- Ex- Ex- Ex- Typical ample ample ample ample ample ASTM Test Range 1 2 3 4 5 Pene- D 5329 28-38 34 29 31 29 16 tration dmm Softening D36 200-208 205.4 203.9 205.8 205.4 213.9 Point, ° F. Tack, D3121 140-190 140 185 160 180 >250 mm (modified) [0037] The data reported in Table 1 shows that only Example 5, which is a crack sealant packaged in accordance with the invention, achieves an improvement in penetration that is better than the typical range observed for such material. The improvement is significant (a ˜52.9% reduction in penetration) as compared with the base material alone (Example 1). This is significant because the higher the penetration test result, the “softer” the crack sealant. For many applications, it is best to have a low penetration test in order to withstand the elements of foot traffic, power steering, and shopping carts. [0038] The data reported in Table 1 also shows that only Example 5, which is a crack sealant packaged in accordance with the invention, achieves an improvement in softening point that is better than the typical range observed for such material. Again, the improvement is significant (a 4.1% increase in softening temperature) as compared with the base material alone (Example 1). This test generally measures the temperature at which the material becomes soft. Areas with warmer climates need to pay close attention to this property because pavement temperatures can exceed 150° F. when the ambient air temperature is only 90° F. A higher softening point is a significant improvement in the performance of the material. [0039] The data reported in Table 1 also shows that only Example 5, which is a crack sealant packaged in accordance with the invention, achieves an improvement in tack. The improvement is greater than >44% (the length of the test surface was 250 mm, and the ball would have continued beyond 250 mm if the test surface was longer), which is significant. It is desirable to have a less tacky surface quickly, so that crews can continue to work sooner. Furthermore, the quick reduction in tack allows crews to apply sealcoat or open the work to traffic sooner than if the crack sealant used was contained within packaging according to the prior art. [0040] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and illustrative examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.	A meltable crack sealant package that includes a polymeric container and a crack sealant material contained therein. The polymeric container includes a bottom portion including a rigid base and an upwardly extending rigid sidewall that terminates in and define an opening. The rigid base and upwardly extending rigid sidewall cooperate to define a reservoir. A rigid lid portion operatively engages with the bottom portion to close off the opening and thereby seal the crack sealant material within the reservoir in a watertight manner. Methods of making and using the meltable crack sealant package are also disclosed.	1
FIELD OF THE INVENTION This invention relates to improvements in and relating to contrast media, and in particular iodinated X-ray contrast media. BACKGROUND OF THE INVENTION Contrast media may be administered in medical imaging procedures, for example X-ray, magnetic resonance and ultrasound imaging, to enhance the image contrast in images of a subject, generally a human or non-human animal body. The resulting enhanced contrast enables different organs, tissue types or body compartments to be more clearly observed or identified. In X-ray imaging, the contrast media function by modifying the X-ray absorption characteristics of the body sites into which they distribute. Clearly however the utility of a material as a contrast medium is governed largely by its toxicity, by its diagnostic efficacy, by other adverse effects it may have on the subject to which it is administered, and by its ease of storage and ease of administration. Since such media are conventionally used for diagnostic purposes rather than to achieve a direct therapeutic effect, when developing new contrast media there is a general desire to develop media having as little as possible an effect on the various biological mechanisms of the cells or the body as this will generally lead to lower animal toxicity and lower adverse clinical effects. The toxicity and adverse biological effects of a contrast medium are contributed to by the components of the medium, e.g. the solvent or carrier as well as the contrast agent and its components (e.g. ions where it is ionic) and metabolites. The following major contributing factors to contrast media toxicity and adverse effects have been identified: the chemotoxicity of the contrast agent, the osmolality of the contrast medium, and the ionic composition (or lack thereof) of the contrast medium. In coronary angiography, for example, injection into the circulatory system of contrast media has been associated with several serious effects on cardiac function. These effects are sufficiently severe as to place limitations on the use in angiography of certain contrast media. In this procedure, for a short period of time a bolus of contrast medium rather than blood flows through the circulatory system and differences in the chemical and physicochemical nature of the contrast medium and the blood that it temporarily replaces can give rise to undesirable effects, e.g. arrhythmias, QT-prolongation, and, especially, reduction in cardiac contractile force and occurrence of ventricular fibrillation. There have been many investigations into these negative effects on cardiac function of infusion of contrast media into the circulatory system, e.g. during angiography, and means for reducing or eliminating these effects have been widely sought. Early injectable ionic X-ray contrast agents, based on triiodophenylcarboxylate salts, were particularly associated with osmotoxic effects deriving from the hypertonicity of the contrast media injected. This hypertonicity causes osmotic effects such as the draining out of water from red-blood cells, endothelial cells, and heart and blood vessel muscle cells. Loss of water makes red blood cells stiff and hypertonicity, chemotoxicity and non-optimal ionic make-up separately or together reduce the contractile force of the muscle cells and cause dilation of small blood vessels and a resultant decrease in blood pressure. The osmotoxicity problem was addressed by the development of the non-ionic triiodophenyl monomers, such as iohexol, which allowed the same contrast effective iodine concentrations to be attained with greatly reduced attendant osmotoxicity effects. The drive towards reduced osmotoxicity led in due course to the development of the non-ionic bis(triiodophenyl) dimers, such as iodixanol, which reduce osmotoxicity associated problems still further allowing contrast effective iodine concentrations to be achieved with hypotonic solutions. This ability to achieve contrast effective iodine concentrations without taking solution osmolality up to isotonic levels (about 300 mOsm/kg H 2 O) further enabled the contribution to toxicity of ionic imbalance to be addressed by the inclusion of various plasma cations, as discussed for example in WO-90/01194 and WO-91/13636 of Nycomed Imaging AS. However X-ray contrast media, at commercial high iodine concentrations of about 300 mgI/ml, have relatively high viscosities, ranging from about 15 to about 60 mPas at ambient temperature with the dimeric media generally being more viscous than the monomeric media. Such viscosities pose problems to the administrator of the contrast medium, requiring relatively large bore needles or high applied pressure, and are particularly pronounced in paediatric radiography and in radiographic techniques which require rapid, bolus administration, e.g. in angiography. SUMMARY OF THE INVENTION The present invention addresses the viscosity problem encountered with the prior art materials and thus viewed from one aspect the invention provides iodinated aryl compounds, useful as X-ray contrast agents, of formula I ##STR2## (wherein n is 0 or 1, and where n is 1 each C 6 R 5 moiety may be the same or different; each group R is a hydrogen atom, an iodine atom or a hydrophilic moiety M or M 1 , two or three non-adjacent R groups in each C 6 R 5 moiety being iodine and at least one, and preferably two or three, R groups in each C 6 R 5 moiety being M or M 1 moieties; X denotes a bond or a group providing a 1 to 7, for example 1, 2, 3 or 4 atom chain linking two C 6 R 5 moieties or, where n is 0, X denotes a group R; each M independently is a non-ionic hydrophilic moiety; and each M 1 independently represents a C 1-4 alkyl group substituted by at least one hydroxyl group and optionally linked to the phenyl ring via a carbonyl, sulphone or sulphoxide group, at least one R group, preferably at least two R groups and especially preferably at least one R group in each C 6 R 5 moeity, being an M 1 moiety; with the proviso that where n is zero either at least one M 1 group other than a hydroxymethyl or 1,2-dihydroxyethyl (and optionally other than any hydroxyethyl) group is present or then if one hydroxymethyl or 1,2-dihydroxyethyl M 1 group (and optionally any hydroxyethyl group) is present at least one nitrogen-attached hydroxylated alkyl (preferably C 1-4 -alkyl) moiety-containing M group is also present) and isomers, especially stereoisomers and rotamers, thereof. DETAILED DESCRIPTION OF THE INVENTION It is found that the compounds of the invention exhibit advantageously low viscosity in aqueous solution; this is thought to derive from the presence of M 1 groups on the phenyl groups, from compound asymmetry and, in the dimer compounds, from the nature of the linker X (especially where X provides a linkage less than 5 atoms in length). Thus for example all of the water-soluble monomer compounds according to the invention that have been tested have exhibited viscosities lower than that of iohexol. The compounds of formula I are preferably asymmetric. For the monomer compounds (where n=0) this may be achieved by asymmetric substitution of the phenyl ring. For the dimers this can be achieved by the use of an asymmetric 2 or more atom chain-forming group X and/or by selection of non-identical C 6 R 5 groups, i.e. by non-identical substitution of the iodophenyl end groups. Asymmetric molecules are preferred as they have been found to have better water-solubility. Such non-identical substitution of the phenyl end groups, the C 6 R 5 moieties, may be achieved by having different numbers or positions of iodine substitution and/or by different numbers, positions or identities of M or M 1 substitution. To maximize iodine loading, triodophenyl end groups, i.e. groups of formula ##STR3## are preferred, and in these the two R groups may be the same or different, although preferably both represent M or M 1 groups. Where a phenyl end group is disubstituted by iodine, it is preferably of formula ##STR4## (where each M 2 may be the same or different and represents an M 1 or M group, at least one on each ring preferably representing an M 1 group). Generally, diiodophenyl-diiodophenyl dimers will be less preferred than the diiodophenyl-triiodophenyl or triiodophenyl-triiodophenyl dimers, due primarily to their reduced iodine loading, i.e. 4 rather than 5 or 6 iodines per dimer molecule. Indeed the triiodophenyl-triiodophenyl dimers are generally preferred due to their higher iodine loading. For the monomers, the triiodophenyl compounds are again preferred. The solubilizing groups M may be any of the non-ionizing groups conventionally used to enhance water solubility. Suitable groups include for example straight chain or branched C 1-10 -alkyl groups, preferably C 1-5 groups, optionally with one or more CH 2 or CH moieties replaced by oxygen or nitrogen atoms and optionally substituted by one or more groups selected from oxo, hydroxy, amino, carboxyl derivative, and oxo substituted sulphur and phosphorus atoms. Particular examples include polyhydroxyalkyl, hydroxyalkoxyalkyl and hydroxypolyalkoxyalkyl and such groups attached to the phenyl group via an amide linkage such as hydroxyalkylaminocarbonyl, N-alkylhydroxyalkylaminocarbonyl and bishydroxyalkylaminocarbonyl groups. Preferred among such groups are those containing 1, 2, 3, 4, 5 or 6, especially 1, 2 or 3, hydroxy groups, e.g. --CONH--CH 2 CH 2 OH --CONH--CH 2 CHOHCH 2 OH --CONH--CH(CH 2 OH) 2 --CON(CH 2 CH 2 OH) 2 as well as other groups such as --CONH 2 --CONHCH 3 --OCOCH 3 --N(COCH 3 )H --N(COCH 3 )C 1-3 -alkyl --N(COCH 3 )-mono, bis or tris-hydroxy C 1-4 -alkyl --N(COCH 2 OH)-mono, bis or tris-hydroxy C 1-4 -alkyl --N(COCH 2 OH) 2 --CON(CH 2 CHOHCH 2 OH) (CH 2 CH 2 OH) --CONH--C(CH 2 OH) 3 and --CONH--CH(CH 2 OH) (CHOHCH 2 OH). In general, the M groups will preferably each comprise a polyhydroxy C 1-4 -alkyl group, such as 1,3-dihydroxyprop-2-yl or 2,3-dihydroxyprop-l-yl. Other such M groups as are conventional within the field of triiodophenyl X-ray contrast agents may also be used and the introduction of M groups onto iodophenyl structures may be achieved by conventional techniques. In general, M 1 groups preferably comprise C 1-4 -alkyl groups substituted by 1, 2, 3 or 4 hydroxy groups (e.g. hydroxymethyl, 2-hydroxyethyl, 2,3-bishydroxypropyl, 1,3-bishydroxyprop-2-yl, 2,3,4-trihydroxybutyl, and 1,2,4-trihydroxybut-2-yl) optionally connected to the phenyl ring via a CO, SO or SO 2 group (e.g. COCH 2 OH or SO 2 CH 2 OH). In the dimeric compounds of the invention, the linker group X is conveniently a bond or a 1 to 7, eg 1, 2, 3 or 4, membered chain comprising carbon, nitrogen, oxygen or sulphur atoms, e.g. a bond, a O, S, N or C one atom chain, a NN, NC, NS, CC or CO two atom chain, or a NCN, OCN, CNC, OCO, NSN, CSN, COC, OCC or CCC three atom chain, for example: an oxygen atom or a group NR 1 , CO, SO 2 or CR 2 1 ; a group COCO, CONR 1 , COCR 2 1 , SOCR 2 1 , SO 2 NR 1 , CR 2 1 CR 2 1 , CR 2 1 NR 1 or CR 1 2 O; a group NR 1 CONR 1 , OCONR 1 , CONR 1 CO, CONR 1 CR 1 2 , OCOO, CR 1 2 OCR 1 2 , OCR 1 2 CO, CR 1 2 CONR 1 , CR 1 2 CR 1 2 CR 1 2 , COCR 1 R 1 CO, CR 1 2 NR 1 CR 1 2 , CR 1 2 SO 2 NR 1 , CR 1 2 OCO or NR 1 SO 2 NR 1 ; where R 1 is hydrogen or a C 1-6 -alkyl or alkoxy group optionally substituted by hydroxy, alkoxy, oxa or oxo (e.g. a polyhydroxyalkyl, formyl, acetyl, hydroxyl, alkoxy or hydroxyalkoxy group) and where it is attached to a carbon atom R 1 may also be a hydroxyl group. When X provides a 4-7 atom linkage, conventional linker groups, such as for example those suggested by Justesa in WO-93/10078 or Bracco in U.S. Pat. No. 4,348,377 and WO-94/14478 may be used. In general such linkages will comprise optionally aza or oxa substituted alkylene chains optionally carring R 1 substituents, especially such groups terminating with imine nitrogen or, more preferably, carbonyl carbon atoms, preferbly belonging to iminocarbonyl functional units within the chain. Hydroxylated chains, such as are found in iodixanol are particularly preferred. Examples of such chains are NCCN, NCCCN, CNCCCNC, and CNCCN, eg. --NR 1 COCONR 1 -- --NR 1 COCR 1 2 CONR 1 -- --NR 1 CR 1 2 CR 1 OHCR 1 2 NR 1 -- --CONR 1 CR 1 2 CONR 1 -- and --N(COR 1 )CR 1 2 CR 1 OHN(COR 1 )--, eg as found in iotrolan, iofratol, ioxaglic acid and iodixanol, or as otherwise indicated in WO-94/14478. Advantageously, in the dimer compounds the X group is not symmetrical. This may be achieved for example by asymmetrical substitution of a symmetrical chain (e.g. N--C--N substituted as NHCONR 1 ) or by selection of an asymmetric chain (e.g. OCN substituted as OCONR 1 ). In particular, it is preferred that the linker group X should be polar and also that it should be hydrophilic. Thus examples of preferred structures according to the invention include: ##STR5## where each M 2 is M 1 or M, at least one in each compound (and preferably on each ring) being M 1 , especially where at least one M 2 is a C 1-4 -alkyl group substituted by 1, 2, 3 or 4 hydroxy groups (e.g. hydroxymethyl, 2-hydroxyethyl, 2,3-bishydroxy-propyl, 1,3-bishydroxyprop-2-yl, 2,3,4-trihydroxybutyl, and 1,2,4-trihydroxybut-2-yl) optionally connected to the phenyl ring via a CO, SO or SO 2 group (e.g. COCH 2 OH or SO 2 CH 2 OH), e.g. a hydroxyalkyl or hydroxyalkylcarbonyl group, in particular a hydroxymethyl, hydroxymethylcarbonyl, 2-hydroxyethyl or 2-hydroxyethylcarbonyl group, and where R 1 is hydrogen, hydroxyl, hydroxyalkyl (e.g. 2-hydroxyethyl), acetyl or hydroxyalkylcarbonyl. Particular preferred compounds are those of formula ##STR6## The compounds of the invention may in general be prepared in two or three stages: (a) dimer formation (where necessary), (b) iodination of phenyl groups and (c) substitution of phenyl groups and/or optionally linker moieties by solubilizing moieties. While, in theory, stages (a), (b) and (c) can be performed in any order, it will generally be preferred to perform the dimer formation step before the iodination step and, for reasons of economy, it will be preferred to perform the iodination step at as late a stage in the synthesis as is feasible so as to reduce iodine wastage. The dimer formation stage may itself be a multi-step procedure with an appropriate activated linker first being attached to one monomer before the resulting linker-monomer conjugate is reacted with a second monomer. Alternatively, dimer formation may be by way of reaction of similarly or cooperatively substituted monomers with the conjugation of the monomers leading to dimer formation. Where desired the linker group X may be produced by modification, e.g. substitution, oxidation or reduction, of a precursor linker, e.g. in a precursor monomer. For the monomer compounds, especially those where ring substitution is asymmetric, iodine loading will generally be effected before or after partial substitution of the phenyl ring with R groups. In all cases, conventional synthetic routes wellknown in the literature (eg methods analogous to those used and described for the production of the compounds referred to in WO-94/14478) may be used. The compounds of the invention may be used as X-ray contrast agents and to this end they may be formulated with conventional carriers and excipients to produce diagnostic contrast media. Thus viewed from a further aspect the invention provides a diagnostic composition comprising a compound of formula I (as defined above) together with at least one physiologically tolerable carrier or excipient, e.g. in aqueous solution in water for injections optionally together with added plasma ions or dissolved oxygen. The contrast agent compositions of the invention may be at ready-to-use concentrations or may be formulated in concentrate form for dilution prior to administration. Generally compositions in ready-to-use form will have iodine concentrations of at least 100 mgI/ml, preferably at least 150 mgI/ml, with concentrations of at least 300 mgI/ml, e.g. 320 to 400 mgI/ml being generally preferred. The higher the iodine concentration the higher the diagnostic value but equally the higher the solution's viscosity and osmolality. Normally the maximum iodine concentration for a given compound will be determined by its solubility, and by the upper tolerable limits for viscosity and osmolality. For contrast media which are administered by injection, the desirable upper limit for solution viscosity at ambient temperature (20° C.) is 30 mPas; however viscosities of up to 50 or even up to 60 mPas can be tolerated although their use in paediatric radiography will then generally be contraindicated. For contrast media which are to be given by bolus injection, e.g. in angiographic procedures, osmotoxic effects must be considered and preferably osmolality should be below 1 Osm/kg H 2 O, especially below 850 mOsm/kg H 2 O, in particular within 50 or less, preferably within 10, mOsm of isotonicity (about 300 mOsm/kg H 2 O). With the compounds of the invention, such viscosity, osmolality and iodine concentration targets can readily be met. Indeed effective iodine concentrations may be reached with hypotonic solutions. It may thus be desirable to make up solution tonicity by the addition of plasma cations so as to reduce the toxicity contribution which derives from ionic imbalance effects following bolus injection. Such cations will desirably be included in the ranges suggested in WO-90/01194 and WO-91/13636. Preferred plasma cation contents for the contrast media of the invention, especially contrast media for angiography, are as follows: ______________________________________sodium 2 to 100, especially 15 to 75, particularly 20 to 70, more particularly 25 to 35 mMcalcium up to 3.0, preferably 0.05 to 1.6, especially 0.1 to 1.2, particularly 0.15 to 0.7 mMpotassium up to 2, preferably 0.2 to 1.5, especially 0.3 to 1.2, particularly 0.4 to 0.9 mMmagnesium up to 0.8, preferably 0.05 to 0.6, especially 0.1 to 0.5, particularly 0.1 to 0.25 mM______________________________________ The plasma cations may be presented, in whole or in part, as counterions in ionic contrast agents. Otherwise they will generally be provided in the form of salts with physiologically tolerable counteranions, e.g. chloride, sulphate, phosphate, hydrogen carbonate, etc., with plasma anions especially preferably being used. Besides plasma cations, the contrast media may contain other counterions where the dimer is ionic and such counterions will of course preferably be physiologically tolerable. Examples of such ions include alkali and alkaline earth metal ions, ammonium, meglumine, ethanolamine, diethanolamine, chloride, phosphate, and hydrogen carbonate. Other counterions conventional in pharmaceutical formulation may also be used. The compositions moreover may contain further components conventional in X-ray contrast media, e.g. buffers, etc. Publications referred to herein are incorporated herein by reference. The invention will now be described further with reference to the following non-limiting Examples. EXAMPLE 1 1,3,5-Triiodo-2,4-di(1,2,3-trihydroxy-1-propyl)-6-(3-hydroxy-1-propen-1-yl)benzene. a. 1,3,5-Triiodo-2,4,6-trimethylbenzene Iodine (19.0 g, 75 mmol) was dissolved in carbon tetrachloride (75 ml). Mesitylene (7.0 ml, 50 mmol) and bis(trifluoroacetoxy)phenyl iodide (35.5 g, 82 mmol) were added and the solution was stirred at ambient temperature for 2 hours. The precipitate, which was collected by filtration, was washed with cold carbon tetrachloride and dried. Yield: 20.5 g (82%). 1 H NMR (CDCl 3 ): 3.31 (s). b. 1,3,5-Triiodo-2,4,6-triacetoxymethylbenzene Triiodomesitylene (19.5 g, 39 mmol) was added to glacial acetic acid (200 ml) containing acetic anhydride (400 ml) and concentrated sulfuric acid (40 ml). Solid potassium permanganate (24.6 g, 156 mmol) was then added in small portions over a period of 3 h. After stirring for 16 h, the solvent was evaporated and water (200 ml) was added. The aqueous suspension was extracted with dichloromethane (250 ml) and the organic phase was washed with water (3×50 ml), dried (MgSO 4 ) and evaporated. The solid residue was suspended in acetone and the white crystalline product was collected by filtration. Yield: 9.3 g (35%). 1 H NMR (CDCl 3 ): 5.66 (s, 6H), 2.20 (s, 9H). c. 1,3,5-Triiodo-2,4,6-trihydroxymethylbenzene 1,3,5-Triiodo-2,4,6-triacetoxymethylbenzene (9.3 g, 13.8 mmol) was suspended in methanol (120 ml) and K 2 CO 3 (0.32 g, 2.3 mmol) was added. The mixture was stirred at ambient temperature for 16 h, and , after neutralization of the solution with 2M aqueous HCl, the organic solvent was evaporated. The residue was suspended in water and the white solid was collected by filtration and washed with water, methanol and ether. Yield: 7.1 g (94%). 1 H NMR (DMSO-d 6 ): 5.08 (s, 6H), 3.35 (br s, 3H) d. 1,3,5-Triiodobenzene-2,4,6-trialdehyde 1,3,5-Triiodo-2,4,6-trihydroxymethylbenzene (4.5 g, 8.2 mmol) was dissolved in DMSO (80 ml). Triethylamine (51.7 ml, 371 mmol) and pyridine.SO 3 (11.8 g, 74.2 mmol) were added and the mixture was stirred for two hours. The two phases were separated and the lower phase was cooled to 0° C., poured into water (150 ml) and stirred for 30 min at 0° C. The white solid was collected by filtration, washed with water and dried. Yield: 3.0 g (67%). 1 H NMR (DMSO-d 6 ): 9.64 (s). e. 1,3,5-Triiodo-2,4,6-tris(2-prop-1-enoic acid)benzene methyl ester Sodium hydride (194 mg 80% in mineral oil, 6.5 mmol) was dissolved in DMSO (13 ml) and triethylphosphonoacetate (1.16 ml, 5.80 mmol) was added. After stirring the solution for 30 min, 1,3,5-triiodobenzene-2,4,6-trialdehyde (700 mg, 1.30 mmol) was added and the reaction mixture was stirred for 16 h. Water (200 ml) was then added and the pH was adjusted to 1 with 2M aqueous HCl. The slurry was extracted with dichloromethane (2×200 ml) and the combined organic phases were washed with water (3×50 ml), dried (MgSO 4 ) and evaporated. Purification by column chromatography (silica gel CH 2 Cl 2 -methanol 99:1) gave the pure product as a white solid. Yield: 426 mg (44%). 1 H NMR (CDCl 3 ): 7.48 (d, 3H, J 16.2 Hz), 5.95 (d, 3H, J 16.2 Hz), 4.30 (q, 6H, J 7.2 Hz), 1.36 (t, 9H, J 7.2 Hz). f. 1,3,5-Triiodo-2,4,6-tris(1-hydroxyprop-en-3-yl)benzene 1,3,5-Triiodo-2,4,6-tris(2-prop-1-enoic acid)benzene methyl ester (650 mg, 0.87 mmol) was dissolved in toluene (10 ml) and diisobutylaluminium hydride (5.44 ml of a 1.2M solution in toluene) was added at 0° C. After stirring for 40 min at 0° C., the solution was poured into methanol (50 ml) and the resulting slurry was stirred for another 45 min. The solids were filtered off and the solution was evaporated giving a white solid residue which was purified by trituration with diethyl ether. Yield: 510 mg (94%). 1 H NMR (CD 3 OD): 6.44 (d, 3H, J 16.0 Hz), 5.57 (dt, 3H, J d 16.0 Hz, J t 5.8 Hz), 4.23 (m, 6H). g. 1,3,5-Triiodo-2,4,6-tris(1-acetoxyprop-en-3-yl)benzene 1,3,5-Triiodo-2,4,6-tris(1-hydroxyprop-en-3-yl)benzene (560 mg, 0.90 mmol) was dissolved in a mixture of pyridine (8 ml) and acetic anhydride (8 ml). After stirring at ambient temperature for 16 hours, the solvent was evaporated and the residue was purified by preparative HPLC (RP-18, CH 3 CN: H 2 O 80:20). Yield 310 mg (46%). 1 H NMR (CDCl 3 ): 6.46 (dt, 3H, J d 16.2 Hz, J t 1.6 Hz), 5.68 (dt, 3H, J d 16.2 Hz, J t 5.6 Hz), 4.83 (dd, 6H, J 1 5.6 Hz, J 2 1.6 Hz), 2.12 (s, 9H). 13 CNMR (CDCl 3 ): 170.6, 146.3, 140.9, 131.5, 98.7, 63.5, 20.9. h. 1,3,5-Triiodo-2,4-di(1,2,3-trihydroxy-1-propyl)-6-(3-hydroxy-1-propen-1-yl)benzene 1,3,5-Triiodo-2,4,6-tris(1-acetoxyprop-en-3-yl)benzene (100 mg, 0.133 mmol) was dissolved in formic acid (5 ml) containing hydrogen peroxide (0.054 ml). The mixture was stirred at ambient temperature for 21 hours and the solvent was evaporated. Methanol (5 ml) was added followed by solid K 2 CO 3 (195 mg), and, after stirring for 1 hour, the solvent was evaporated. The product was purified by preparative HPLC (CH 3 CN: H 2 O 3:97). 1 H NMR (D 2 O): 6.45 (d, 1H, J 16.0 Hz), 5.40-5.55 (m, 1H), 4.54-4.90 (m, 11H), 4.23-4.31 (m, 2H), 3.62-3.91 (m, 4H). MS (ESP): 692 (M + ). EXAMPLE 2 1,3,5-Triiodo-2,4,6-tri(1,2,3-trihydroxy-1-propyl)benzene. 1,3,5-Triiodo-2,4,6-tris(1-acetoxyprop-en-3-yl)benzene (100 mg, 0.133 mmol, from Example 1g) was dissolved in formic acid (5 ml) containing hydrogen peroxide (0.081 ml). The mixture was stirred at room temperature for 40 hours and the solvent was evaporated. Methanol (5 ml) was added followed by solid K 2 CO 3 (195 mg), an, after stirring for 1 h, the solvent was evaporated. The product was purified by preparative HPLC (CH 3 CN:H 2 O 3:97). 1 H NMR (CD 3 OD): 4.57-4.94 (m, 15H), 3.62-3.99 (m, 6H). MS (ESP): 744 (M+18). EXAMPLE 3 N-Acetyl-3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-N-(2,3-dihydroxypropyl)-2,4,6-triiodoaniline a. 1-Hydroxymethyl-3-nitro-5-benzoic acid methyl ester 1-Nitroisophthalic acid monomethyl ester (22.5 g, 100 mmol) was dissolved in dry THF (675 ml) and BF 3 •Et 2 O (25.2 ml, 200 mmol) was added. NaBH 4 (5.1 g, 135 mmol) was then added portionwise during 1 h. After stirring for 2 additional h, ethanol (20 ml) was added slowly followed by water (200 ml) and diethyl ether (400 ml). The phases were separated and the aqueous phase was extracted once with diethyl ether (100 ml). The combined organic phases were washed with a saturated aqueous solution of NaHCO 3 , dried (Na 2 SO 4 ) and evaporated. Yield: 20 g (96%). HPLC analysis indicated >95% purity of the product. 1 H NMR (CDCl 3 ): 8.72 (s, 1H), 8.42 (s, 1H), 8.32 (s, 1H), 4.86 (s, 2H), 3.97 (s, 3H), 2.37 (br s, 1H). b. 1-Hydroxymethyl-3-nitro-5-(2,3-dihydroxypropylaminocarbonyl)benzene The methyl ester from Example 3a (20.5 g, 97 mmol) was mixed with 2,3-dihydroxypropylamine (9.6 g, 106 mmol) and the mixture was heated to 90° C. After 45 min, the pressure was reduced to 200 mm Hg and heating was continued for 2 h. The crude product , which was >95% pure according to HPLC analysis, was used without further purification in the next step. Yield: 22.8 g (87%). 1 H NMR (CD 3 OD): 8.57 (s, 1H), 8.38 (s, 1H), 8.19 (s, 1H), 4.77 (s, 2H), 3.81-3.88 (m, 1H), 3.39-3.63 (m, 4H). c. 3-Hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)aniline 1-Hydroxymethyl-3-nitro-5-(2,3-dihydroxypropylaminocarbonyl)benzene (12.0 g, 44.4 mmol) was hydrogenated in methanol (150 ml) at 60 psi H 2 using Pd/C (10%, 100 mg) as the catalyst. The catalyst was removed by filtration and the residue was evaporated. Addition of methanol (10 ml) precipitated the product as a white solid which was filtered off and dried. Yield: 6.6 g (62%). 1 H NMR (CD 3 OD): 7.05-7.09 (m, 1H), 6.98-7.03 (m, 1H), 6.83-6.87 (m, 1H), 4.53 (s, 2H), 3.77-3.85 (m, 1H), 3.8-3.59 (m, 4H), 3.32-3.42 (m, 1H). MS (ESP, m/e): 241 ( M+1! + , 100%). d. 3-Hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodoaniline 3-Hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)aniline (500 mg, 2.1 mmol) was dissolved in water (175 ml) and an aqueous solution of KICl 2 (70%, w/w) was added in portions of 0.1 ml during 8 h. A total amount of 1.0 ml KICl 2 solution was added. After a total reaction time of 6 h, the solution was extracted with ethyl acetate (1000 ml) which was separated and washed with an aqueous solution of Na 2 S 2 O 3 (0.2M, 100 ml). Evaporation followed by purification by preparative HPLC gave 432 mg (33%) of the pure product. 1 H NMR (CD 3 OD): 5.10 (s, 2H), 3.90-3.98 (m, 1H), 3.72 (ddd, J 1 =0.7 Hz, J 2 =4.2 Hz, J 3 =11.4 Hz), 1H), 3.60 (dd, J 1 =6.0 Hz, J 2 =11.4 Hz, 1H), 3.49 (ddd, J 1 =1.2 Hz, J 2 =6.0 Hz, J 3 =13.5 Hz, 1H), 3.37 (ddd, J 1 =1.2 Hz, J 2 =6.1 Hz, J 3 =13.2 Hz, 1H), 2.62 (s, 1H), 2.28 and 2.34 (2s, 2H). MS (ESP, m/e): 618 (M + , 100%), 640 ( M+Na! + , 55%). e. N-acetyl-3-acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline 3-Hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodoaniline (3.3 g, 5.3 mmol) was suspended in glacial acetic acid (12 ml) containing acetic anhydride (48 ml) and concentrated sulfuric acid (0.08 ml). The mixture was stirred at 60° C. for 3 h, allowed to cool to room temperature, and CH 2 Cl 2 (100 ml) and water (100 ml) were added. The organic phase was washed with water (3×50 ml) and a saturated aqueous solution of NaHCO 3 (2×50 ml). After drying (MgSO 4 ) and evaporation, the residue was dissolved in a mixture of CH 2 Cl 2 and methanol (9:1) and filtered through a short silica pad and evaporated. Yield: 3.0 g (71%). 1 H NMR (CDCl 3 ): 8.27-8.32 (m, 1H), 5.51 (s, 2H), 5.18-5.22 (m, 1H), 4.17-4.42 (m, 2H), 3.67-3.84 (m, 1H), 3.41-3.60 (m, 1H), 2.56 (s, 3H), 2.04-2.14 (8s, 12H). MS (ESP, m/e): 786 (M + , 100%), 809 ( M+Na! + , 81%). f. N-Acetyl-3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-N-(2,3-dihydroxypropyl)-2,4,6-triiodoaniline N-acetyl-3-acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline (1.0 g, 1.27 mmol) was suspended in a mixture of methanol (6 ml) and water (30 ml) and pH was adjusted to 12.0 using a 2M aqueous solution of NaOH. After stirring for 1 h, 1-bromo-2,3-propanediol (0.99 g, 6.4 mmol) was added and the pH was adjusted to 11.6 using a 2M aqueous solution of HCl. 1-Bromo-2,3-propanediol (0.99 g, 6.4 mmol) was again added after 16 and 18 h and after 24 h, pH was adjusted to 6.5 using a 2M aqueous solution of HCl. After evaporation, the residue was purified by preparative HPLC. Yield: 0.373 g (40%). 1 H NMR (D 2 O): 5.20 (s, 2H), 3.23-3.99 (m, 12H), 1.79 (2s, 3H). MS (ESP, m/e): 734 (M + , 60%), 756 ( M+Na! + , 100%). EXAMPLE 4 N,N'-bis(hydroxyacetyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. 3,5-Diaminobenzylalcohol A solution of 3,5-dinitrobenzylalcohol (2.20 g, 11.1 mmol) in methanol (90 ml) and a Pd/C catalyst (10%, 100 mg) was hydrogenated in a Parr apparatus at 60 psi. The solution was filtered and the solvent was removed by evaporation. The crude product was used without purification in the next step. 1 H NMR (CDCl 3 ): 6.12-6.14 (m, 2H), 5.96-5.98 (m, 1H), 4.51 (s, 2H), 3.60 (br s, 4H). b. 3,5-Diamino-2,4,6-triiodobenzylalcohol The crude product from the previous example dissolved in a mixture of methanol (310 ml) and water (60 ml) and pH was adjusted to 1.5 using a 4M aqueous solution of HCl. A solution of KICl 2 (70%, 11.2 g) was added dropwise at such a rate, that the color disappeared between each addition. After stirring for 5 additional min, the precipitate was filtered off and washed with water (3×50 ml), ether (3×50 ml) and dried. Yield: 4.50 g (80%). 1 H NMR (DMSO-d 6 ): 5.20 (s, 4H), 4.81-4.94 (m, 3H). c. 3,5-Diamino-2,4,6-triiodobenzylacetate 3,5-Diamino-2,4,6-triiodobenzylalcohol (4.42 g, 8.56 mmol) was dissolved in a mixture of pyridine (50 ml) and acetic anhydride (2.5 ml) and the mixture was stirred at room temperature for 16 h. The solvents were evaporated and the residue was washed with ether (3×50 ml), water (3×50 ml) and dried. Yield: 4.52 g (95%). 1 H NMR (DMSO-d 6 ): 5.35 (s, 2H), 5.28 (s, 4H), 2.04 (s, 3H). 13 C NMR (DMSO-d 6 ): 170.5, 148.1, 139.0, 78.0, 73.6, 70.0, 20.8. d. 3,5-Bis(acetoxyacetylamino)-2,4,6-triiodobenzylacetate 3,5-Diamino-2,4,6-triiodobenzylacetate (5.58 g, 10 mmol) was mixed with acetoxyacetyl chloride (3.22 ml, 30 mmol) and dimethylacetamide (50 ml) and the mixture was stirred for 17 h. Ether (600 ml) was added, and after 20 min, the precipitate was collected, washed with water (3×50 ml) and dried. Recrystallization from acetonitrile gave 3.3 g (44%) of the pure product. 1 H NMR (DMSO-d 6 ): 10.27 and 10.19 (2s, 2:1, 2H), 5.51 (s, 2H), 4.66 (s, 4H), 2.13 (s, 3H), 2.12 (s, 3H), 2.06 (s, 3H). e. N,N'-bis(hydroxyacetyl)-3,5-diamino-2,4,6-triiodobenzylalcohol 3,5-Bis(acetoxyacetylamino)-2,4,6-triiodobenzylacetate (152 mg, 0.2 mmol) was dissolved in a mixture of methanol (6 ml) and 1M aqueous NaOH (2 ml) and the solution was stirred for 2 h at room temperature. After neutralization with 1M HCl, the solvents were removed by evaporation and the product was purified by preparative HPLC. Yield: 105 mg (83%). MS (ESP, m/e): 655 ( M+Na! + , 100%). EXAMPLE 5 N,N'-Bis(hydroxyacetyl)-N-(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(acetoxyacetyl)-N-(2-acetoxyethyl)-3,5-diamino-2,4,6-triiodobenzylacetate 3,5-Bis(acetoxyacetylamino)-2,4,6-triiodobenzylacetate (2.15 g, 2.84 mmol) was dissolved in a mixture of DMSO (5 ml) and dimethylacetamide (5 ml) containing Cs 2 CO 3 (1.0 g, 3.07 mmol) and 2-bromoethyl acetate (0.31 ml, 2.84 ml). The mixture was stirred at room temperature for 48 h, ether (100 ml) and aqueous NaH 2 PO 4 buffer were added and the organic phase was washed with water and dried. Purification by preparative HPLC gave 520 mg (22%) of the product. 1 H NMR (CDCl 3 ): 7.86 (s, 1H), 5.66 (s, 2H), 4.80 (s, 2H), 3.81-4.44 (m, 6H), 2.13-2.27 (m, 12H). MS (ESP, m/e): 845 ( M+1! + , 100%), 866 ( M+Na! + , 24%). b. N,N'-Bis(hydroxyacetyl)-N-(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(acetoxyacetyl)-N-(2-acetoxyethyl)-3,5-diamino-2,4,6-triiodobenzylacetate (0.50 g, 0.59 mmol) was dissolved in a mixture of methanol (5 ml), water (5 ml) and aqueous 1M NaOH (1 ml). The solution was stirred for 2 h, pH was adjusted to 2 using aqueous HCl and the product was purified by preparative HPLC. Yield: 240 mg (67%). 1 H NMR DMSO-d 6 ): 9.85 (br s, 1H), 5.77 (br s, 1H), 4.79-5.26 (m, 3H), 3.20-3.71 (m, 6H). MS (ESP, m/e): 676 (M + , 57%), 698 ( M+Na! + , 100%). EXAMPLE 6 N,N'-Bis(hydroxyacetyl)-N,N'-bis(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol 3,5-Bis(acetoxyacetylamino)-2,4,6-triiodobenzylacetate (190 mg, 0.25 mmol), prepared according to Example 4, was dissolved in dimethylacetamide (5 ml) under an argon atmosphere. 2-Bromoethyl acetate (0.22 ml, 2.0 mmol) and K 2 CO 3 (138 mg, 1.0 mmol) were added. After 16 h, DMSO (1.5 ml), 2-bromoethyl acetate (0.22 ml, 2.0 mmol) and K 2 CO 3 (138 mg, 1.0 mmol) were added and the suspension was stirred for another 24 h. Aqueous NaH 2 PO 4 was added and the resulting solution was extracted with ether (3×25 ml). The combined organic phases were washed with water (4×20 ml) and then dried (MgSO 4 ). The solvent was removed by evaporation and the residue, a colorless oil, was dissolved in a mixture of methanol (3 ml) an 1M aqueous NaOH (3 ml). The solution was stirred for 1 h, pH was adjusted to 6 using aqueous HCl and the solvents were removed by evaporation. Purification by preparative HPLC gave 60 mg (33%) of the product. MS (ESP, m/e): 720 (M + , 100%), 742 ( M+Na! + , 36%). EXAMPLE 7 N,N'-Bis(hydroxyacetyl)-N-(2,3-dihydroxypropyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(acetoxyacetyl)-N- (2,2-dimethyl-1,3-dioxolane-4-yl)-methyl!-3,5-diamino-2,4,6-triiodobenzylacetate 3,5-Bis(acetoxyacetylamino)-2,4,6-triiodobenzylacetate (90 mg, 0.12 mmol), prepared according to Example 4, was dissolved in a mixture of dimethylacetamide (3 ml) and DMSO (3 ml). 4-Bromomethyl-2,2-dimethyl-1,3-dioxolane (0.097 g, 0.5 mmol) and Cs 2 CO 3 (0.10 g, 0.3 mmol) were added and the solution was stirred at room temperature for 48 h. Aqueous NaH 2 PO 4 was added and the solution was extracted with ether (3×25 ml). The combined organic phases were washed with water (3×15 ml), dried (MgSO 4 ) and evaporated. Purification by preparative HPLC gave 36 mg (35%) of the pure product. 1 H NMR (DMSO-d 6 ): 10.30 (br s, 1H), 5.53 (s, 2H), 3.61-4.68 (m, 9H), 2.13 (s, 3H), 2.07 (s, 3H), 2.06 (s, 3H), 1.17-1.34 (m, 6H). MS (ESP, m/e): 894 ( M+Na! + , 100%), 910 ( M+K! + , 11%). b. N,N'-Bis(hydroxyacetyl)-N-(2,3-dihydroxypropyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(acetoxyacetyl)-N- (2,2-dimethyl-1,3-dioxolane-4-yl)-methyl!-3,5-diamino-2,4,6-triiodobenzylacetate (36 mg, 0.042 mmol) was dissolved in a mixture of methanol (3 ml) and water (4 ml) and the pH was adjusted to 12 using a 1M aqueous solution of NaOH. After stirring for 2 h, pH was adjusted to 1 using 1M aqueous HCl and stirring was continued for 16 h. The solution was neutralized with an aqueous NaH 2 PO 4 buffer, the solvents were removed by evaporation and the residue was purified by preparative HPLC to give 24 mg (81%) of the pure product. MS (ESP, m/e): 704 (M + , 100%), 726 ( M+Na! + , 34%). EXAMPLE 8 N,N'-Bis(2-hydroxypropionyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(2-acetoxypropionyl)-3,5-diamino-2,4,6-triiodobenzylacetate 3,5-Diamino-2,4,6-triiodobenzylacetate (2.79 g, 5.0 mmol) was dissolved in dimethylacetamide (25 ml) and cooled to 0° C. 2-Acetoxypropionyl chloride (3.73 g, 25 mmol) was added dropwise and the mixture was stirred at room temperature for 17 h. The solvents were evaporated and the residue was triturated with diethyl ether. The solid residue was then purified by flash chromatography on silica gel using a mixture of CH 2 Cl 2 and acetonitrile (5:1) as the eluent. Yield: 2.21 g (56%). 1 H NMR (DMSO-d 6 ): 10.20-10.23 (m, 2H), 5.52 (s, 2H), 5.21-5.24 (m, 2H), 2.06-2.13 (m, 9H), 1.51 (d, J=6.9 Hz, 6H). b. N,N'-Bis(2-hydroxypropionyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2-acetoxypropionyl)-3,5-diamino-2,4,6-triiodobenzylacetate (0.16 g, 0.2 mmol) was dissolved in a mixture of methanol (5 ml) and water (5 ml) and the pH was adjusted to 12 using a 1M aqueous solution of NaOH. After stirring for 15 h, the solution was neutralized with 1M HCl and the solvents were removed by evaporation. Purification by preparative HPLC gave 61 mg (46%) of the pure product. MS (ESP, m/e): 660 (M + , 5%), 682 ( M+Na! + , 100%), 698 ( M+K! + , 17%). EXAMPLE 9 N,N'-Bis(2-hydroxypropionyl)-N-(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(2-acetoxypropionyl)-N-(2-acetoxyethyl)-3,5-diamino-2,4,6-triiodobenzylacetate N,N'-Bis(2-acetoxypropionyl)-3,5-diamino-2,4,6-triiodobenzylacetate (393 mg, 0.50 mmol) was dissolved in a mixture of dimethylacetamide (4 ml) and DMSO (4 ml) containing 2-bromoethyl acetate (0.083 g, 0.50 mmol) and Cs 2 CO 3 (244 mg, 0.75 mmol). The mixture was stirred for 17 h, water (20 ml) was added and the mixture was extracted with ether (3×25 ml). The combined organic phases were washed with water (3×20 ml), dried (MgSO 4 ) and evaporated. The residue was purified by preparative HPLC to give 80 mg (18%) of pure product. 1 H NMR (CD 3 OD): 5.72-5.82 (m, 2H), 5.20-5.42 (m, 2H), 3.55-4.48 (m, 4H), 1.90-2.24 (m, 12H), 1.66 (d, J=7.1 Hz, 6H). MS (ESP, m/e): 1004 ( M+Cs! + , 100%). b. N,N'-Bis(2-hydroxypropionyl)-N-(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2-acetoxypropionyl)-N-(2-acetoxyethyl)-3,5-diamino-2,4,6-triiodobenzylacetate (120 mg, 0.14 mmol) was dissolved in a mixture of water (7 ml) and methanol (7 ml) and pH was adjusted to 12 using an 1M aqueous solution of NaOH. The mixture was stirred for 2 h, pH was adjusted to 7 with aqueous HCl and the solvents were evaporated. The product was purified by preparative HPLC. Yield: 70 mg (72%). 1 H NMR (CD 3 OD): 5.27-5.34 (m, 2H), 4.31-4.41 (m, 1H), 3.82-4.12 (m, 4H), 3.55-3.73 (m, 1H), 1.51-1.60 (m, 3H), 1.23-1.32 (m, 3H). MS (ESP, m/e): 726 ( M+Na! + , 100%). EXAMPLE 10 N,N'-Bis(2-hydroxypropionyl)-N,N'-bis(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(2-acetoxypropionyl)-N,N'-bis(2-acetoxyethyl)-3,5-diamino-2,4,6-triiodobenzylacetate N,N'-Bis(2-acetoxypropionyl)-3,5-diamino-2,4,6-triiodobenzylacetate (197 mg, 0.25 mmol) was dissolved in a mixture of dimethylacetamide (5 ml) and DMSO (1.5 ml) containing 2-bromoethyl acetate (0.11 ml, 1.0 mmol) and Cs 2 CO 3 (162 mg, 0.50 mmol). The mixture was stirred for 67 h, water (20 ml) was added and the mixture was extracted with ether (2×75 ml). The combined organic phases were washed with water (5×75 ml), dried (Na 2 SO 4 ) and evaporated. The residue was purified by preparative HPLC to give 35 mg (15%) of pure product. 1 H NMR (DMSO-d 6 ): 5.49-5.73 (m, 2H), 4.97-5.22 (m, 2H), 3.49-4.00 (m, 6H), 1.86-12.08 (m, 15H), 1.09-1.58 (m, 6H). b. N,N'-Bis(2-hydroxypropionyl)-N,N'-bis(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2-acetoxypropionyl)-N,N'-bis(2-acetoxyethyl)-3,5-diamino-2,4,6-triiodobenzylacetate (175 mg, 0.18 mmol) was dissolved in a mixture of methanol (8 ml) and water (8 ml) and pH was adjusted to 12 with 1M aqueous NaOH. After stirring for 3 h, the solution was neutralized with aqueous HCl. Purification by preparative HPLC gave 50 mg (37%) of the pure product. 1 H NMR (CD 3 OD): 5.26-5.38 (m, 2H), 3.44-4.08 (m, 6H), 1.32-1.59 (m, 6H). MS (ESP, m/e): 770 ( M+Na! + , 100%). EXAMPLE 11 N,N'-Bis(2-hydroxypropionyl)-N-(2,3-dihydroxypropyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(acetoxypropionyl)-N- (2,2-dimethyl-1,3-dioxolane-4-yl)-methyl!-3,5-diamino-2,4,6-triiodobenzylacetate N,N'-Bis(2-acetoxypropionyl)-3,5-diamino-2,4,6-triiodobenzylacetate (393 mg, 0.50 mmol) was dissolved in a mixture of DMSO (4 ml) and dimethylacetamide (4 ml) containing Cs 2 CO 3 (1.80 g, 5.52 mmol) and 4-bromomethyl-2,2-dimethyl-1,3-dioxolane (1.0 ml). The mixture was stirred for 7 days and was then worked up analogous to Example 7a. Purification by preparative HPLC gave 115 mg (26%) of the pure product. 1 H NMR (CD 3 OD): 5.61-5.5.75 (m, 2H), 5.03-5.44 (m, 2H), 3.47-4.55 (m, 6H), 1.98-2.23 (m, 9H), 1.30-1.71 (m, 12H). MS (ESP, m/e): 922 ( M+Na! + , 100%). b. N,N'-Bis(2-hydroxypropionyl)-N-(2,3-dihydroxypropyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(acetoxypropionyl)-N- (2,2-dimethyl-1,3-dioxolane-4-yl)-methyl!-3,5-diamino-2,4,6-triiodobenzylacetate (115 mg, 0.13 mmol) was dissolved in a mixture of methanol (8 ml) and water (8 ml) and pH was adjusted to 12 with aqueous 1M NaOH. After 2.5 h, pH was adjusted to 1 with 2M aqueous HCl. After stirring for 17 h, the solution was neutralized with an aqueous NaH 2 PO 4 buffer and the solvents were removed evaporation. Purification by preparative HPLC gave 65 mg (69%) of the pure product. MS (ESP, m/e): 756 ( M+Na! + , 100%) EXAMPLE 12 N,N'-Bis(2,3-dihydroxypropionyl)-3,5-diamino-2,4,6-triiodobenzylalcohol a. N,N'-Bis(2,2-dimethyl-1,3-dioxolane-4-carbonyl)-3,5-diamino-2,4,6-triiodobenzylacetate 3,5-Diamino-2,4,6-triiodobenzylacetate (3.54 g, 6.3 mmol) and 2,2-dimethyl-1,3-dioxolane-4-carboxylic acid chloride (3.13 g, 19 mmol) were dissolved in dimethylacetamide (40 ml) and the solution was stirred for 3.5 h. The solvent was removed by evaporation and the residue was treated with an aqueous solution of NaHCO 3 . The crystalline residue was filtered off, washed with water and dried. Purification by flash chromatography using a mixture of CH 2 Cl 2 and CH 3 CN (3:1) as the eluent gave 1.90 g (37%) of the pure product. 1 H NMR (DMSO-d 6 ): 9.93-10.02 (m, 2H), 5.30 (s, 2H), 4.58 (t, J=6.2 Hz, 1H), 4.29 (t, J=7.3 Hz, 1H), 4.10 (t, J=6.1 Hz, 1H), 2.06 (s, 3H), 1.54 (s, 3H), 1.38 (s, 3H). MS (ESP, m/e): 902 ( M+dimethylacetamide! + , 100%). b. N,N'-Bis(2,3-dihydroxypropionyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2,2-dimethyl-1,3-dioxolane-4-carbonyl)-3,5-diamino-2,4,6-triiodobenzylacetate (1.25 g, 1.55 mol) was dissolved in a mixture of water (50 ml), methanol (25 ml) and concentrated HCl (0.5 ml). After stirring for 4 h, the solution was neutralized with aqueous NaH 2 PO 4 and the solvents were removed by evaporation. The residue was dissolved in water (10 ml) and the pH was adjusted to 12 with aqueous NaOH. After 30 min, the solution was again neutralized and the solvent was evaporated. The product was purified by preparative HPLC. Yield: 483 mg (45%). 1 H NMR (9.65-9.83 (m, 2H), 5.77 (s, 2H), 5.20 (s, 1H), 4.95-5.03 (m, 2H), 4.81 (s, 2H), 4.00-4.08 (m, 2H), 3.72-3.82 (m, 2H), 3.50-3.63 (m, 2H). MS (ESP, m/e): 692 (M + , 62%), 714 ( M+Na! + , 100%). EXAMPLE 13 N,N'-Bis(2,3-dihydroxypropionyl)-N-(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2,2-dimethyl-1,3-dioxolane-4-carbonyl)-3,5-diamino-2,4,6-triiodobenzylacetate (204 mg, 0.25 mmol) was dissolved in a mixture of dimethylacetamide (4 ml) and DMSO (2.5 ml) containing Cs 2 CO 3 (650 mg, 2.0 mmol) and 2-bromoethyl acetate (0.035 ml, 0.31 mmol). After stirring for 1 week, ether (150 ml) and a NaH 2 PO 4 buffer (100 ml) were added, the organic phase was separated and the aqueous phase was extracted with ether (150 ml). The combined organic phases were then washed with water (6×100 ml), dried (Na 2 SO 4 ) and evaporated. The residue was dissolved in a mixture of methanol (20 ml) and water (20 ml) and pH was adjusted to 12 with aqueous NaOH. After stirring for 1 h, the pH was adjusted to 1.5 with concentrated HCl and stirred for another 16 h. The solution was neutralized with aqueous NaH 2 PO 4 and the solvents were evaporated. Preparative HPLC gave 55 mg (30%) of the pure product. MS (ESP, m/e): 736 (M + , 28%), 758 ( M+Na! + , 100%). EXAMPLE 14 N,N'-Bis(2,3-dihydroxypropionyl)-N,N'-bis(2-hydroxyethyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2,2-dimethyl-1,3-dioxolane-4-carbonyl)-3,5-diamino-2,4,6-triiodobenzylacetate (204 mg, 0.25 mmol) was dissolved in a mixture of dimethylacetamide (5 ml) and DMSO (1.5 ml) containing K 2 CO 3 (276 mg, 2.0 mmol) and 2-bromoethyl acetate (0.44 ml, 4.0 mmol). After stirring for 48 h, an aqueous NaH 2 PO 4 buffer was added and the mixture was extracted with ether (2×150 ml). The combined organic phases were washed with water (6×100 ml), dried (Na 2 SO 4 ) and evaporated. The solid residue was dissolved in a mixture of methanol (12 ml) and water (12 ml) and the pH was adjusted to 12 with aqueous NaOH. After stirring for 18 h, the solution was acidified with concentrated HCl (0.70 ml) and stirring was continued for 3 h. The solution was neutralized and the solvents were removed by evaporation. The product was purified by preparative HPLC. Yield: 98 mg (50%). MS (ESP, m/e): 802 ( M+Na! + n 100%). EXAMPLE 15 N,N'-Bis(2,3-dihydroxypropionyl)-N-(2,3-dihydroxypropyl)-3,5-diamino-2,4,6-triiodobenzylalcohol N,N'-Bis(2,2-dimethyl-1,3-dioxolane-4-carbonyl)-3,5-diamino-2,4,6-triiodobenzylacetate (408 mg, 0.50 mmol) was dissolved in a mixture of dimethylacetamide (4 ml) and DMSO (4 ml) containing Cs 2 CO 3 (1.80 g, 5.52 mmol) and 2,2-dimethyl-1,3-dioxolane-4-carboxylic acid chloride (2.0 ml). After stirring for 8 days, aqueous NaH 2 PO 4 (100 ml) was added and the mixture was extracted with diethyl ether (2×150 ml). The combined organic phases were washed with water (6×100 ml), dried (Na 2 SO 4 ) and evaporated. The residue was dissolved in a mixture of methanol (10 ml) and water (10 ml) and pH was adjusted to 12 with aqueous NaOH. After stirring for 2 h, concentrated HCl (1.0 ml) was added and stirring was continued for 16 h. After neutralization, the solvents were evaporated and the residue was purified by preparative HPLC. Yield: 149 mg (39%). MS (ESP, m/e): 766 (M + , 60%), 788 ( M+Na! + , 100%). EXAMPLE 16 Oxalic bis 3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodobenzeneamide! a. 3-Acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline 3-Hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodoaniline (1.89 g, 3.06 mmol) prepared according to Example 3d, was dissolved in a mixture of acetic anhydride (5 ml) and pyridine (5 ml). The mixture was stirred at room temperature for 24 h, CH 2 Cl 2 (100 ml) was added and the solution was washed with water (3×25 ml), with a saturated aqueous solution of NaHCO 3 , dried (Na 2 SO 4 ) and evaporated. The product was purified by flash chromatography on silica gel using a mixture of CH 2 Cl 2 and methanol (98:2) as the eluent. Yield: 1.30 g (57%). 1 H NMR (CDCl 3 ): 6.10-6.25 (m, 1H), 5.48 (s, 2H), 5.20-528 (m, 1H), 4.22-4.43 (m, 2H), 3.53-3.89 (m, 2H), 2.06-2.13 (m, 9H). MS (ESP, m/e): 744 (M + , 100%). b. Oxalic bis 3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodobenzeneamide! 3-Acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline (100 mg, 0.134 mmol) was dissolved in dioxane (1.0 ml) and the solution was heated to 90° C. Oxalyl chloride (0.096 mmol) was added and the mixture was stirred at 78° C. for 17 h. After cooling to room temperature, water (1.0 ml) was added and pH was adjusted to 12 with aqueous NaOH. After stirring for 4 h, the solution was neutralized, the solvents were evaporated and the residue was purified by preparative HPLC. Yield: 14 mg (16%). 1 H NMR (CD 3 OD): 5.24 (s, 2H), 3.38-4.03 (m, 10H). MS (ESP. m/e): 1290 (M + , 33%), 1312 ( M+Na! + , 100%). EXAMPLE 17 Malonic bis 3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodobenzeneamide! 3-Acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline (100 mg, 0.134 mmol) prepared according to Example 16a, was dissolved in dioxane (1.0 ml) and malonyl chloride (0.097 mmol) was added. The mixture was stirred at 90° C. for 2 h and the solution was allowed to cool to room temperature. Water (1 ml) was added and pH was adjusted to 12 with aqueous NaOH. After stirring at 60° C. for 18 h, the solution was neutralized and the solvents were evaporated. The product was purified by preparative HPLC. Yield: 34 mg (39%). MS (ESP, m/e): 1304 (M + , 68%), 1326 ( M+Na! + , 100%). EXAMPLE 18 N,N'-diacetyl-N,N'-bis 3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodophenyl!-1,3-diamino-2-hydroxypropane N-acetyl-3-acetoxymethyl-5-(2,3-acetoxypropylaminocarbonyl)-2,4,6-triiodoaniline (300 mg, 0.38 mmol) prepared according to Example 3e was dissolved in a mixture of water (1.2 ml) and methanol (0.2 ml) and pH was adjusted to 12 with aqueous NaOH. Epichorohydrine (0.28 mmol) was added and the mixture was stirred at room temperature for 65 h. The solution was neutralized and the product was isolated by preparative HPLC. Yield: 60 mg (20%). MS (ESP, m/e): 1398 ( M+Na! + , 100%). EXAMPLE 19 N- 3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodophenyl!-N' 3,5-bis(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodophenyl!urea a. N- 3-acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodophenyl!-N' 3,5-bis(2,3-dihacetoxypropylaminocarbonyl)-2,4,6-triiodophenyl!urea 3,5-Bis(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline (260 mg, 0.30 mmol) was dissolved in dioxane (1.0 ml) and a solution of phosgene in toluene (1.93M, 1.8 ml) was added. The flask was tightly sealed and then heated to 60° C. for 17 h. After cooling to room temperature, the solvent was distilled off at reduced pressure. Dioxane (3 ml) was added and distilled off again. This procedure was repeated twice. Dioxane (1 ml) was added followed by 3-acetoxymethyl-5-(2,3-diacetoxypropylaminocarbonyl)-2,4,6-triiodoaniline (0.245 g, 0.31 mmol), prepared according to Example 16a, and Hg(OCOCF 3 ) 2 (20 mg). The mixture was stirred for 16 h at room temperature, the solvent was evaporated and the residue was purified by preparative HPLC. Yield: 0.192 g (39%). MS (ESP, m/e): 1643 (M + , 100%), 1665 ( M+Na! + , 34%). b. N- 3-hydroxymethyl-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodophenyl!-N' 3,5-bis(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodophenyl!urea The product from Example 19a was dissolved in a mixture of methanol (5 ml) and water (5 ml) and the pH was adjusted to 12 using a 2M aqueous solution of NaOH. After stirring for 2 h, the pH was adjusted to 6.5 using aqueous HCl and the solvents were evaporated. The product was purified using preparative HPLC. Yield: 68 mg (44%). MS (ESP, m/e): 1349 (M + , 15%), 1372 ( M+Na! + , 100%). EXAMPLE 20 N-Hydroxyacetyl-3-(1,2-dihydroxyethyl)-5-(2,3-dihydroxypropylaminocarbonyl)-2,4,6-triiodoaniline a. 3-Nitro-5-(2-trimethylsilylvinyl)benzoic acid methyl ester A mixture of 3-iodo-5-nitrobenzoic acid methyl ester (307 mg, 1.0 mmol), Pd(OAc) 2 (67 mg, 0.30 mmol), triphenylphosphine (0.032 g, 0.60 mmol), AgNO 3 (170 mg, 1.0 mmol), triethylamine (0.167 ml, 1.2 mmol) and vinyltrimethylsilane (0.309 ml, 2.0 mmol) was dissolved in acetonitrile (10 ml) and the solution was heated to 60° C. in a closed vessel for 48 h. The precipitated salts were filtered off and the filtrate was evaporated. The residue was chromatographed on silica gel using a mixture of ethyl acetate and heptane (1:11) as the eluent. Yield: 210 mg (75%). 1 H NMR (CDCl 3 ): 8.70-8.73 (m, 1H), 8.36-8.47 (m, 2H), 6.93 (d, J=19.2 Hz, 1H), 6.75 (d, J=19.2 Hz, 1H), 3.99 (s, 3H), 0.20 (s, 9H). MS (APci, m/e): 279 (M + , 100%). b. 3-Nitro-5-vinylbenzoic acid methyl ester 3-Nitro-5-(2-trimethylsilylvinyl)benzoic acid methyl ester (2.44 g, 8.71 mmol) was dissolved in acetonitrile (150 ml), the solution was heated to reflux temperature and HCl gas was bubbled through the solution until the starting material had disappeared according to HPLC analysis. The solution was allowed to cool and the solvent was removed by evaporation. The residue was >95% pure according to HPLC and was used without further purification. Yield: 2.02 g (89%). 1 H NMR (CD 3 CN): 8.64 (s, 1H), 8.54 (s, 1H), 8.45 (s, 1H), 6.96 (dd, J 1 =10.8 Hz, J 2 =17.4 Hz, 1H), 6.11 (d, J=17.4 Hz, 1H), 5.59 (d, J=10.8 Hz, 1H), 4.00 (s, 3H). c. 3-Nitro-5-(1,2-dihydroxyethyl)benzoic acid methyl ester 3-Nitro-5-vinylbenzoic acid methyl ester (2.02 g, 9.76 mmol) was dissolved in a mixture of acetone and water (200 ml, 9:1), and, after cooling to 0° C., OsO 4 (60 mg, 0.24 mmol) was added followed by N-methylmorpholine-N-oxide (2.34 g, 20.0 mmol). After stirring for 46 h at room temperature, an aqueous solution of Na 2 S 2 O 5 (3.7 g) in water (150 ml) was added and the solution was acidified with dilute aqueous HCl. The volume of the solution was reduced to 150 ml by evaporation and the residue was extracted with ethyl acetate (3×100 ml). The combined organic phases were evaporated and the residue was purified by column chromatography on silica gel using ethyl acetate as the eluent. Yield: 1.60 g (60%). 1 H NMR (CD 3 CN): 8.62-8.66 (m, 1H), 8.44-8.48 (m, 1H), 8.36-8.40 (m, 1H), 4.88-4.94 (m, 1H), 3.98 (s, 3H), 3.60-3.79 (m, 4H). d. 1-(2,3-Dihydroxypropylaminocarbonyl)-3-nitro-5-(1,2-dihydroxyethyl)benzene 3-Nitro-5-(1,2-dihydroxyethyl)benzoic acid methyl ester (0.40 g, 1.69 mmol) and 2,3-dihydroxypropylamine (0.17 g, 1.86 mmol) were dissolved in methanol (2 ml) and the solution was stirred at 75° C. for 1 h. The pressure was then reduced to 200 mm Hg and stirring was continued at 95° C. for 2 h. The crude reaction mixture was purified by preparative HPLC. Yield: 0.40 g (78%). MS (ESP. m/e): 299 ( M-1! + , 100%). e. 3-(2,3-Dihydroxypropylaminocarbonyl)-5-(1,2-dihydroxyethyl)aniline 1-(2,3-Dihydroxypropylaminocarbonyl)-3-nitro-5-(1,2-dihydroxyethyl)benzene (0.40 g, 1.32 mmol) was dissolved in a mixture of methanol (40 ml) and water (20 ml). The solution was hydrogenated at 60 psi using a Pd/C catalyst (10%, 50 mg). The solution was filtered through celite and the solvents were removed by evaporation. The product was >95% pure by HPLC analysis and was used without further purification. MS (ESP, m/e): 271 ( M+1! + , 100%), 293 ( M+Na! + , 45%). f. 3-(2,3-Dihydroxypropylaminocarbonyl)-5-(1,2-dihydroxyethyl)-2,4,6-triodoaniline 3-(2,3-Dihydroxypropylaminocarbonyl)-5-(1,2-dihydroxyethyl)aniline (0.37 g, 1.35 mmol) was dissolved in a mixture of methanol (30 ml) and water (90 ml). KICl 2 (1.37 g, 4.05 mmol) was added and the solution was stirred at 35° C. for 24 h. Additional KICl 2 (1.0 mmol) was added, and stirring was continued at 60° C. for 72 h. An aqueous solution of Na 2 S 2 O 5 (1.0 g in 50 ml) was added and the solvents were removed by evaporation. Purification by preparative HPLC gave 87 mg (10%) of the pure product. 1 H NMR (CD 3 OD): 8.60 (m, 1H), 5.38-5.47 (m, 1H), 3.96-4.26 (m, 3H), 3.30-3.84 (m, 10H). MS (ESP, m/e): 648 (M + , 15%), 670 ( M+Na! + , 100%). g. N-Hydroxyacetyl-3-(2,3-dihydroxypropylaminocarbonyl)-5-(1,2-dihydroxyethyl)-2,4,6-triodoaniline 3-(2,3-Dihydroxypropylaminocarbonyl)-5-(1,2-dihydroxyethyl)-2,4,6-triodoaniline (0.059 d, 0.091 mmol) was mixed with acetoxyacetyl chloride (1.0 ml) containing N,N-dimethylacetamide (0.4 ml) and the mixture was stirred at 60° C. for 48 h. The mixture was allowed to cool to room temperature, water was added and the solvents were removed by evaporation. The residue was dissolved in a mixture of methanol (10 ml) and water (5 ml) and an aqueous solution of NaOH (5M, 1 ml) was added. The solution was stirred at room temperature for 1 h, the solution was neutralized with aqueous HCl and the solvents were evaporated. Purification by HPLC gave the pure product. MS (ESP, m/e): 706 (M + , 100%). EXAMPLE 21 3,5-Di(hydroxyacetylamino)-2,4,6-triiodoacetophenone a. 1,3-Diamino-5-(1-hydroxyethyl)benzene 3,5-Dinitroacetophenone (2.02 g, 9.5 mmol) which had been prepared according to the literature procedure (Y. Nagase et al., Macromol. Chem. Rapid Comm. (1990) 11, 185-191) was dissolved in methanol (100 ml) and hydrogenated at 60 psi using a Pd/C catalyst (5%, 100 mg). The catalyst was filtered off and the solvent was removed by evaporation. The product was used without purification in the next step. Yield: 1.22 g (84%). 1 H NMR (CDCl 3 ): 6.20 (d, J=2.0 Hz, 2H), 6.08 (t, J=2.0 Hz, 1H), 4.90 (br s, 4H), 4.62 (q, J=7.0 Hz, 1H), 3.37 (d, J=7.0 Hz, 3H). MS (ESP, m/e): 151 ( M-1! + , 100%). b. 1,3-Diamino-2,4,6-triiodoacetophenone 1,3-Diamino-5-(1-hydroxyethyl)benzene (1.18 g, 7.72 mmol) was dissolved in a mixture of methanol and water (5:1, 168 ml) containing 1M aqueous HCl (16 ml). An aqueous solution of KICl 2 (7.31 g, 30.9 mmol) was added quickly, and, after stirring for 50 min, the solid was filtered off, washed with water and dried. The product was pure by TLC and 1 H NMR analysis. Yield: 3.62 g (89%). 1 H NMR CDCl 3 ): 4.86 (br s, 4H), 2.62 (s, 3H). 13 C NMR (CDCl 3 ): 204.7, 151.1, 146.8, 28.7. MS (APci, m/e): 528 (M + , 100%). c. 1,3-Di(acetoxyacetylamino)-2,4,6-triiodoacetophenone 1,3-Diamino-2,4,6-triiodoacetophenone (1.8 g, 3.41 mmol) was dissolved in dimethylacetamide (15 ml) containing acetoxyacetyl chloride (1.1 ml, 10.2 mmol) and the solution was stirred for 65 h at room temperature. The solvents were removed by evaporation and the residue was purified by preparative HPLC. Yield: 1.69 g (68%). 1 H NMR DMSO-d 6 ): 10.13-10.27 (m, 2H), 4.65 (s, 4H), 2.56 (s, 3H), 2.12 (s, 6H). MS (ESP, m/e): 750 ( M+Na! + , 100%), 766 ( M+K! + , 26%). d. 1,3-Di(hydroxyacetylamino)-2,4,6-triiodoacetophenone 1,3-Di(acetoxyacetylamino)-2,4,6-triiodoacetophenone (0.171 g, 0.23 mmol) was dissolved in a mixture of methanol (30 ml) and water (5 ml) containing 2M aqueous NaOH (3 ml). The solution was stirred for 90 min and was then neutralized using a strongly acidic cation exchange resin. The solvents were removed by evaporation and the residue was purified by preparative HPLC. Yield: 98 mg (54%). MS (ESP, m/e): 644 (M + , 100%), 666 ( M+Na! + , 95%). EXAMPLE 22 3,5-Di(hydroxyacetylamino)-1-hydroxyacetyl-2,4,6-triiodobenzene a. 3,5-Di(acetoxyacetylamino)-1-bromoacetyl-2,4,6-triiodobenzene 1,3-Di(acetoxyacetylamino)-2,4,6-triiodoacetophenone (0.20 g, 0.279 mmol) was dissolved in glacial acetic acid and bromine (0.044 g, 0.28 mmol) was added. The reaction was stirred at 2.5 h at 75° C. and then allowed to cool. The solvents were removed by evaporation and the residue was used directly in the next step. MS (ESP, m/e): 806 (M + , 100%), 808 (M + , 98%). b. 3,5-Di(acetoxyacetylamino)-1-acetoxyacetyl-2,4,6-triiodobenzene 3,5-Di(acetoxyacetylamino)-1-bromoacetyl-2,4,6-triiodobenzene (10 mg, 0.12 mmol) was converted into the corresponding acetate by heating to 110° C. in glacial acetic acid (5 ml) containing sodium acetate (1 mmol) and AgOCOCF 3 (0.11 g, 0.5 mmol) for 16 h. The product was purified by preparative HPLC. The yield was not determined. MS (ESP, m/e): 786 (M + , 100%). c. 3,5-Di(hydroxyacetylamino)-1-hydroxyacetyl-2,4,6-triiodobenzene Hydrolysis of 3,5-di(acetoxyacetylamino)-1-acetoxyacetyl-2,4,6-triiodobenzene was carried out analogous to Example 4e. The crude product was purified by preparative HPLC. The yield was not determined. MS (ESP, m/e): 687 ( M+HCOOH! + , 100%). EXAMPLE 23 3,5-Di(hydroxyacetylamino)-1-(1,2-dihydroxyethyl)-2,4,6-triiodobenzene a. 3,5-Dinitrophenylethanol 3,5-Dinitroacetophenone (3.27 g, 0.0156 mol) was dissolved in a mixture of absolute ethanol (75 ml) and THF (37.5 ml) and the mixture was cooled to -10° C. NaBH 4 (0.30 g, 7.9 mmol) was added and the mixture was stirred for 1 h at -10° C. Water (80 ml) and ethyl acetate were added, the phases were separated and the organic phase was washed with water (80 ml) and dried (Na 2 SO 4 ). The solvents were removed by evaporation and the residue was purified by chromatography on neutral alumina using a is mixture of pentane and ethyl acetate (1:1) as the eluent. Yield: 2.52 g (76%). 1 H NMR (CDCl 3 ): 8.95 (t, J=2.0 Hz, 1H), 8.60 (d, J=2.0 Hz, 1H), 8.59 (d, J=2.0 Hz, 1H), 5.15 (q, J=7.5 Hz, 1H), 1.61 (d, J=7.5 Hz, 3H). b. 3,5-Dinitrostyrene 3,5-Dinitrophenylethanol (1.0 g, 4.7 mmol) was mixed with P 2 O 5 (1.0 g, 0.71 mmol) and the stirred mixture was heated to 100° C. After 3 h, the mixture was allowed to cool to room temperature and water (0.4 ml) was added. The pH was adjusted to 9 using 1M aqueous NaOH and extracted with diethyl ether (2×25 ml). The combined organic phases were dried (Na 2 SO 4 ) and evaporated. The crude product was used without further purification in the next step. 1 H NMR CDCl 3 ): 8.92 (t, J=2.0 Hz, 1H), 8.56 (d, J=2.0 Hz, 2H), 6.86 (dd, J 1 =18.4 Hz, J 2 =10.9 Hz, 1H), 6.08 (d, J=18.0 Hz, 1H), 5.67 (d, J=10.9 Hz, 1H). c. 1-(1,2-Dihydroxyethyl)-3,5-dinitrobenzene 3,5-Dinitrostyrene (0.50 g, 2.58 mmol) was dissolved in a mixture of acetone and water (8:1, 70 ml) and the solution was cooled to 0° C. OsO 4 (0.046 g, 0.18 mmol) and NMO (0.60 g, 5.15 mmol) were added and the solution was stirred at room temperature for 16 h. A solution of Na 2 S 2 O 5 (1.5 g) in water (120 ml) was added and the organic solvent removed by evaporation. The aqueous phase was extracted with ethyl acetate (2×70 ml) and the combined organic phases were dried (Na 2 SO 4 ) and evaporated. The product was purified by preparative HPLC. Yield: 0.44 g (75%). 1 H NMR (CD 3 CN): 8.87 (t, J=2.0 Hz, 1H), 8.63 (t, J=2.0 Hz, 2H), 4.98 (t, J=6.0 Hz, 1H), 3.64-3.79 (m, 2H), 2.34 (s, 2H). MS (ESP - , m/e): 227 (M - , 50%), 197 ( M-CH 2 O! - , 100%). d. 1-(1,2-Dihydroxyethyl)-3,5-diaminobenzene 1-(1,2-Dihydroxyethyl)-3,5-dinitrobenzene (0.10 g, 0.44 mmol) was dissolved in methanol (35 ml) and hydrogenation was carried out at 60 psi using a Pd/C catalyst (10%, 50 mg). The catalyst was filtered off and the solution was evaporated. Yield: 0.074 g (100%). 1 H NMR (CD 3 OD): 6.14 (d, J=2.0 Hz, 2H), 6.06 (t, J=2.0 Hz, 1H), 4.98 (br s, 6H), 4.43-4.50 (m, 1H), 3.52-3.57 (m, 2H). MS (ESP, m/e): 170 (M + , 100%), 210 ( M+K! + , 18%). e. 1-(1,2-Dihydroxyethyl)-3,5-diamino-2,4,6-triiodobenzene 1-(1,2-Dihydroxyethyl)-3,5-diaminobenzene (0.0584 g, 0.242 mmol) was dissolved in a mixture of methanol (5 ml) and aqueous 2M HCl (1.2 ml) and a solution of KICl 2 (70% in water, 0.97 mmol) was added in one portion. After stirring for 20 min at room temperature, a 10% aqueous NaHSO 3 solution (0.2 ml) was added, the solvents were removed by evaporation and the residue was purified by preparative HPLC. Yield: 31.4 mg (24%). 1 H NMR (CD 3 OD): 5.56-5.63 (m, 1H), 4.03-4.12 (m, 1H), 3.79-3.87 (m, 1H), 5.06 (br s, 4H). f. 1-(1,2-Dihydroxyethyl)-3,5-di(hydroxyacetylamino)-2,4,6-triiodobenzene 1-(1,2-Dihydroxyethyl)-3,5-diamino-2,4,6-triiodobenzene is acylated with acetoxyacetyl chloride using for example such a procedure as described in Example 4d. The crude product is then hydrolyzed analogous to Example 4e to give the final product. Purification of the crude product is carried out using preparative HPLC.	The invention provides low viscosity iodinated aryl compounds, useful as X-ray contrast agents, of formula I ##STR1## (wherein n is 0 or 1, and where n is 1 each C 6 R 5 moeity may be the same or different; each group R is a hydrogen atom, an iodine atom or a hydrophilic moiety M or M 1 , two or three non-adjacent R groups in each C 6 R 5 moiety being iodine and at least one, and preferably two or three, R groups in each C 6 R 5 moiety being M or M 1 moieties; X denotes a bond or a group providing a 1 to 7 atom chain linking two C 6 R 5 moieties or, where n is 0, X denotes a group R; each M independently is a non-ionic hydrophilic moiety; and each M 1 independently represents a C 1-4 alkyl group substituted by at least one hydroxyl group and optionally linked to the phenyl ring via a carbonyl, sulphone or sulphoxide group, at least one R group being an M 1 moiety; with the proviso that where n is zero either at least one M 1 group other than a hydroxymethyl or 1,2-dihydroxyethyl group is present or then if one hydroxymethyl or 1,2-dihydroxyethyl M 1 group is present at least one nitrogen-attached or hydroxylated-C 3-4 alkyl moiety-containing M group is also present) and isomers thereof.	2
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved endless power transmission belt construction and to a transverse belt element therefor as well as to a method of making such a belt construction. 2. Prior Art Statement It is known to provide an endless power transmission belt construction comprising an endless flexible carrier means and a plurality of transverse belt elements assembled on the carrier means, each belt element comprising a plurality of parts secured together to define opening means passing transversely therethrough and receiving the carrier means therein. For example, see the U.S. patent to Vollers, No. 4,080,841; the U.S. patent to Russ, Sr., No. 4,177,687; the U.S. patent to Cole, Jr., et al, No. 4,313,730; the Swiss Pat. No. 256,918 and the copending U.S. patent application of Carl A. Stiles, Ser. No. 562,551, filed Dec. 19, 1983. It is also known to provide a metal clip that surrounds a toothed belt construction so as to form a plurality of transverse belt elements thereon. For example, see the U.S. patent to Cicognani, No. 4,193,312. SUMMARY OF THE INVENTION It is one feature of this invention to provide an improved endless power transmission belt construction which is particularly adapted to be utilized for continuously variable transmission purposes and the like. In particular, it is believed according to the teachings of this invention that each transverse belt element for such an endless power transmission belt construction can have a plurality of parts which can be assembled on the flexible carrier means of the belt construction in such a unique manner that one of the parts of each belt element can be snap-fitted over the remaining parts thereof to hold all of the parts of that belt element in their assembled relation on the carrier means. For example, one embodiment of this invention provides an endless power transmission belt construction comprising an endless flexible carrier means that has a longitudinal axis, and a plurality of transverse belt elements assembled on the carrier means, each belt element comprising a plurality of parts secured together to define opening means passing transversely therethrough and receiving the carrier means therein. One of the parts of each belt element comprises a generally C-shaped clip that in a direction substantially transverse to the longitudinal axis of the carrier means snaps over and substantially encircles and holds the remaining parts of the respective belt element in their assembled relation. Accordingly, it is an object of this invention to provide an improved power transmission belt construction having one or more of the novel features of this invention as set forth above or hereinafter shown or described. Another object of this invention is to provide an improved method of making such a power transmission belt construction, the method of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described. Another object of this invention is to provide an improved transverse belt element for such a power transmission belt construction or the like, the transverse belt element of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described. Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side view of a transmission means that includes the improved endless power transmission belt construction of this invention. FIG. 2 is an enlarged cross-sectional view of a portion of the endless ower transmission belt construction of FIG. 1. FIG. 3 is a fragmentary top perspective view of part of the belt construction of FIG. 2. FIG. 4 is an enlarged side view of one of the belt elements of this invention and is taken on line 4--4 of FIG. 3 with the carrier means removed therefrom. FIG. 5 is a cross-sectional view taken on line 5--5 of FIG. 4. FIG. 6 is a reduced exploded perspective view of the parts of the belt element of FIG. 4. FIG. 7 is an enlarged cross-sectional view of one of the carrier means of the belt construction of FIGS. 1-4. FIG. 8 is a fragmentary top perspective view of part of another belt construction of this invention. FIG. 9 is an enlarged side view of one of the belt elements of the belt construction of FIG. 8 and is taken in the direction of the line 9--9 thereof with the carrier means removed. FIG. 10 is a cross-sectional view taken on line 10--10 of FIG. 9. FIG. 11 is an enlarged cross-sectional view of the carrier means of the belt construction of FIG. 8. DESCRIPTION OF THE PREFERRED EMBODIMENTS While the various features of this invention are hereinafter illustrated and described as providing an endless power transmission belt construction particularly adapted to be utilized for continuously variable transmission purposes, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide a belt construction for other uses as desired. Therefore, this invention is not to be limited to only the embodiments illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention. Referring now to FIG. 1, a conventional continuously variable transmission arrangement is generally indicated by the reference numeral 20 and comprises a pair of rotatable pulleys 21 and 22, one of which is to be driven by the other thereof by means of an endless power transmission belt construction of this invention that is generally indicated by the reference numeral 23 and which operates in a manner conventional in the art. The pulleys 21 and 22 have variable diameters in a manner well known in the art whereby a continuously variable transmission is provided by the arrangement 20 in a manner well known in the art and as set forth in the U.S. patent to Vollers, No. 4,080,841; the U.S. patent to Cole, Jr., et al, No. 4,313,730 and the Swiss Pat. No. 256,918 whereby these two U.S. patents and this Swiss patent are being incorporated into this disclosure by this reference thereto. Since the operation of a continuously variable power transmission arrangement is well known in the art, a further description of the arrangement 20 need not be set forth as the features of this invention are directed to the endless power transmission belt 23 and will now be described. The endless power transmission belt construction 23 of this invention comprises an endless carrier means that is generally indicated by the reference numeral 24 and a plurality of transverse belt elements that are generally indicated by the reference numeral 25 and are carried by the carrier means 24 in a manner hereinafter set forth, the carrier means 24 comprising a plurality of substantially cylindrical bands 26 formed in a manner hereinafter set forth. Each transverse belt element 25 of this invention defines a substantially trapezoidal configuration when viewed in the manner illustrated in FIG. 4, each belt element 25 comprising three parts 27, 28 and 29 adapted to be assembled together on the carrier means 24 in a manner hereinafter set forth by the part 27 snap-fitting around the parts 28 and 29 to hold the parts 27, 28 and 29 in their assembled relation on the carrier means 27. In particular, the part 27 comprises a generally C-shaped clip or shell having opposed hooking ends 30 for a purpose hereinafter set forth. The clip 27 can be formed of any suitable material, such as metallic material and can be coated on the exterior thereof with a durable polymeric mateial as the opposed sides 31 thereof will engage against the faces of the pulleys 21 and 22 whereby the clip 27 for each belt element 25 performs a dual function, namely, fastens the parts 27, 28 and 29 together and provides the wear surface means 31 for the resulting belt element 25. The clip or shell 27 has opposed side edges 32 extending along the same for a purpose hereinafter set forth, the side edge 32 being suitably slit at the elbows of the clip to permit the legs 31 and hooking ends to perform a snap-fit function as hereinafter described. The parts 28 and 29 of each belt element 25 respectively comprise an outer block 28 and an inner block 29 formed from any suitable material, such as polymeric material, metallic material or combinations of material as desired, each block 28 and 29 having a peripheral edge surface 33 and opposed substantially flat front and rear surfaces 34 and 35 or 35 and 34 depending upon the direction of movement of the belt construction 23 as will be apparent hereinafter. The front and rear surfaces 34 and 35 of the outer block 28 of each belt element 25 are disposed substantially parallel to each other while the front and rear surfaces 34 and 35 of the inner block 29 of the respective belt element converge toward each other as the surfaces 34 and 35 extend away from the other block 28 as illustrated in FIG. 5. The peripheral edge surface 33 of the outer block 28 of each belt element 25 has a substantially flat outer surface section 36 joining with angled substantially flat side surface sections 37 by arcuate surface sections 36' as illustrated, the surface sections 37 converging toward each other as the surfaces 37 join with a substantially flat inner surface section 38 that is interrupted by a plurality of recesses 39 which define substantially semi-circular channels for a purpose hereinafter described. The lower block 29 of each belt element 25 has the peripheral surface 33 provided with a substantially flat top surface section 40 that is interrupted by a plurality of recesses 41 which are generally semi-circular in cross section and are adapted to mate with the recesses 39 in the upper part 28 when the two are placed together in the manner illustrated in FIG. 4 with the surface section 40 against the surface section 38 to define a plurality of openings 42 between the assembled parts 28 and 29 as illustrated in FIG. 5. However, the recesses 41 in the lower block 29 also define inner surfaces 43 in the lower block 29 which are substantially arcuate as illustrated in FIG. 5 to accommodate the bending of the carrier means 24 around the minimum effective diameter of the pulleys 21 and 22 for a purpose well known in the art. The peripheral edge surface means 33 of each lower block 29 of each belt element 25 has opposed substantially flat side surface sections 44 that converge toward each other as they extend away from the surface section 40 and join with a lower substantially flat surface section 45 that is interrupted by a pair of recesses 46 that respectively define arcuate surface sections 47 adjacent the side surface sections 44 and recesses 46 as illustrated in FIG. 4 to respectively receive the hooking ends 30 of the respective clip 27 when the parts 27, 28 and 29 are assembled together in a manner hereinafter set forth. The side surface sections 44 of the lower block 29 complement the side surface sections 37 of an upper block 28 so as to be covered by the sides 31 of the clip 27 in the manner illustrated in FIG. 4 while the clip 27 has an upper substantially flat surface section 48 mating with the surface section 36 of the upper block 28 in the manner illustrated in FIG. 4. While each recess 46 in the end surface section 45 of the lower block 29 of each belt element 25 defines a substantially smooth concave surface 48', each recess 46 also defines a small side opening 49 for a purpose hereinafter set forth. Therefore, it can be seen that the parts 27, 28 and 29 of each belt element 25 of this invention can be formed in a relatively simple manner from desired materials to make the belt construction 23 of this invention in a manner now to be described. Each belt element 25 is assembled to the cylindrical bands 26 of the carrier means 24 by first disposing the outer and inner blocks 28 and 29 around the bands 26 so that the bands 26 will be respectively received in the resulting openings 42 as the surface sections 40 and 38 are brought together. Thereafter, the part or clip 27 is disposed over the part 28 and the hooking ends 30 thereof are spread apart and uncurled so as to cause the hooking ends 30 to pass over the opposed sides 37, 44 of the assembled blocks 28 and 29 until the ends 30 hook in snap-fitting manner around the rounded parts 47 of the lower block 29 to be received into the recesses 46 as illustrated in FIGS. 3 and 4. In this manner, it is believed that the clips 27 can be utilized to snap-fit the parts 28 and 29 together onto the carrier means 24 to complete the belt construction 23 in the manner illustrated in FIGS. 1-3. However, should it be necessary to replace a belt element 25 on the carrier means 24 or one or more parts 27, 28 and 29 thereof, it can be seen that a suitable tool could be inserted in the uncovered part of the openings 49 in the lower block 29 as illustrated in FIG. 4 to pry the hooking ends 30 of the clip 27 out of the recesses 46 to remove the clip 27 and, thus, the parts 28 and 29 from the carrier means 24. The removed clip 27 can then be utilized to form a new belt element 25 if the removed clip 27 was not the reason for changing the removed belt element 25. When the C-shaped clip 27 is snap-fit over the parts 28 and 29 in the manner previously described, it can be seen that the small side edges 32 of the clip 27 engage against the front and rear faces 34 and 35 of the blocks 28 and 29 so as to hold the same in the configuration as illustrated in FIG. 5 and thereby prevent sliding movement between the blocks 28 and 29 in a direction along the carrier means 24. While each belt element 25 of this invention can have any suitable size and configuration, it is believed that the same can be a bidirectional pusher type transverse belt element as the front and rear sides 34 and 35 of the blocks 28, and 29 are substantially the same so that it can be seen in FIG. 2 that the belt construction 23 can move in either a clockwise direction or counterclockwise direction as the belt elements 25 will function in the same manner on the carrier means 24. The blocks 28 and 29 of the belt elements 25 can be formed of a relative size so that the carrier means 24 is located approximately one-third of the distance from the outside surface of each belt element 25 whereby the blocks 28 would each have a height of approximately one-half of the height of each of the lower blocks 29. Also, the overall size of each belt element 25 could be approximately 1.0 inch high, 0.50 of an inch thick and 1.0 to 2.0 inches wide with the angled faces 34 and 35 on each lower block 29 defining an included angle to allow contact for pushing of the belt elements 25 as the belt construction 23 travels around the pulley as illustrated in FIG. 2. As previously stated, to reduce bending stresses in the carrier means 24, the surfaces 43 in the respective openings 42 are radiused below the center lines of the openings 42 to conform to the minimum operating bending radius as illustrated in FIG. 2. While the substantially cylindrical bands 26 of the carrier means 24 could be formed of any suitable structure and in any suitable manner, the same can comprise a round metallic wire rope that has been coated with polymeric material to minimize chafing and abrasion of mating surfaces of the carrier means 24 with the belt elements 25. For example, reference is now made to FIG. 7 wherein one of the bands 26 is illustrated in cross section and comprises a central core member 50 formed of fiber, metal or other suitable material and having six strands 51 of seven metal wires 52 each laid in left Lang lay over the core 50 together with an outer layer of twelve strands 53 of seven metal wires 54 each laid in a right regular lay whereby the resulting band 26 is of the non-rotating type. When making the band 26 to be endless, the opposed ends of the band 26 could be woven or welded together by conduction in a manner to minimize a "stiff" section in the resulting rope or band 26. As previously stated, the band 26 could have the wires 52 and 54 impregnated with a suitable polymeric material that is indicated by the reference numeral 55 in FIG. 7 so as to form a generally circular outer peripheral surface 56 that would minimize chafing and abrasion of the band 26 against the belt elements 25 as is well known in the art. The number of bands 26 for the belt construction 23 as well as the diameter of each band 26 would depend on the tensile strength required for the carrier means 24 for the particular application of the belt construction 23. While the carrier means 24 for the belt construction 23 has been illustrated as comprising a plurality of bands 26, it is to be understood that the same could comprise a single flat band member or a plurality of flat band members disposed in stacked relation in a manner conventional in the art. For example, reference is now made to FIG. 11 wherein another carrier means of this invention is generally indicated by the reference numeral 57 and has a substantially rectangular cross-sectional configuration and is formed from a flat wire rope 58 that is impregnated with a polymeric material 59 to form the substantially rectangular configuration. For example, the flat wire rope 58 can comprise a number of four-strand rope units 60 place side-by-side and stitched together with soft steel sewing wire (not shown), each wire unit 60 comprising a plurality of metal wires 61 as illustrated. In any event, the recess means 39 and 41 respectively for the blocks 28 and 29 could be changed from the multiple arrangement illustrated in FIGS. 1-6 to form a single elongated flat opening that is generally indicated by the reference numeral 62 in FIGS. 8, 9 and 10 to accommodate the substantially flat carrier band 57 illustrated in FIGS. 8 and 11 or other carrier means as desired. Thus, since the parts of the belt elements illustrated in FIGS. 8, 9 and 10 are substantially the same as the belt elements 25 previously described, like reference numerals are being utilized for the belt construction and belt elements illustrated in FIGS. 8, 9 and 10 as the same functions and is formed in the same manner as the belt construction 23 previously described except for the resulting shape of the opening means thereof for the carrier means 57. Accordingly, it can be seen that the blocks 28 and 29 can be modified in a simple manner to permit the use of various types of carrier means as desired. In fact, it is believed that the belt elements 25 of this invention could be fixed in any suitable manner to any suitable carrier means so as to be carried thereby rather than be of the pusher type previously described. In view of the above, it can be seen that this invention not only provides an improved endless power transmission belt construction and method of making the same, but also this invention provides an improved transverse belt element for such an endless power transmission belt construction. While the forms and methods of this invention now preferred have been illustrated and described as required by the Patent Statute, it is to be understood that other forms and method steps can be utilized and still fall within the scope of the appended claims.	An endless power transmission belt construction and a transverse belt element therefor as well as a method of making the same are provided, the belt construction comprising an endless flexible carrier that has a longitudinal axis and a plurality of transverse belt elements assembled on the carrier. Each belt element comprises a plurality of parts secured together to define an opening passing transversely therethrough and receiving the carrier therein. One of the parts of each belt element comprise a generally C-shaped clip that in a direction substantially transverse to the longitudinal axis of the carrier snaps over and substantially encircles and holds the remaining parts of the respective belt element in their assembled relation.	5
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the end of a cloth-overlap. 2. Description of the Background Conventionally, in a case where an upper cloth is sewn on a lower cloth by a sewing machine, the machine has to be stopped upon detection of the end of a cloth-overlap or a stepped portion formed at a terminus of the upper cloth on the lower cloth. For detecting the end of the cloth-overlap or the stepped portion, a sensor is employed. That is to say, the sensor includes a light emitting portion, a light receiving portion opposing the light emitting portion and a controller which drives the sewing machine. The sensor is provided at an upstream side of a needle and is set on a path along which the cloths are fed by a feed-dog. When the end of the cloth-overlap or the stepped portion is brought into opposition to the light emitting portion during the feeding of both of the cloths, the amount of light is decreased, with the controller then stopping the sewing machine. However, when both cloths are of thin thickness, a sufficient change in the amount of light sometimes cannot be received by the light receiving portion. Therefore, it is feared that the sewing machine is not stopped despite non-existence of the upper cloth on the lower cloth. SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to provide an apparatus for detecting the end of a cloth-overlap without the aforementioned drawback. The above and other objects are achieved in accordance with the present invention by providing a new and improved apparatus for detecting the end of a cloth-overlap, including a light emitter for emitting light, a light-receiver for receiving light from the light-emitter, adjusting means for adjusting the amount of light to be emitted from the light-emitter, storing means for storing plural data each of which includes a transmissivity of the lower cloth and a transmissivity of the upper cloth and the lower cloth arranged in a layered configuration, and selecting means for selecting optimum data from the plural stored data and controlling the adjusting means to adjust the amount of light to be emitted from the light-emitter to be optimum based on the selected optimum data. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: FIG. 1 is a side view of a sewing machine to which an apparatus according to the present invention is installed; FIG. 2 is a portion of a front view of the sewing machine shown in FIG. 1; FIG. 3 is a block diagram of a circuit of the apparatus according to the present invention; FIG. 4 is a front view of an operating panel of the apparatus of the present invention; FIG. 5 is a flow chart which shows a main-routine for operating the apparatus of the present invention; FIG. 6 is a flow-chart showing a sub-routine for checking the transmissivity of a lower cloth; FIG. 7 is a flow-chart showing a sub-routine for checking the transmissivity of an upper cloth and the lower cloth in a layered configuration; FIG. 8 is a flow-chart showing a sub-routine for setting optimal sensitivity; FIG. 9 is a side view of a sewing machine including an apparatus according to a second embodiment of the present invention; FIG. 10 is a pattern of a front view of a sewing machine to which the second embodiment of the present invention is applied; and FIG. 11 is a block diagram of a circuit of the apparatus according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1, 2 and 3, thereof, a bracket 2 is secured to a side plate of a sewing machine S. A sensor device includes a casing 3 which is swingably connected to the bracket 2. In the casing 3, an emitter 5 from which light is emitted to a throat plate 4 is accommodated. In the throat plate 4, there is provided a receiver 6 opposing the emitter 5 for receiving light therefrom. A controller 10 in the form of a microprocessor CPU is electrically connected to the emitter 5 and the receiver 6 so as to operate in such a manner that the sewing machine is stopped upon a change in the amount of light detected by the receiver 6. It should be noted that this function of the controller 10 is well-known. As shown in FIGS. 3 and 4, ports P3 and P4 are electrically connected to the emitter 5 via a light-amount adjusting means including a control voltage setting circuit 11, a current setting circuit 12, and LED driving circuit 13 and pulse-generating circuit 14. Thus, according to the outputs of the ports P3 and P4, a number of pulses corresponding to the amount of light to be emitted from the emitter 5 is supplied to the LED driving circuit 13 from the pulse-generating circuit 14. The receiver 6 is electrically connected to differential-amplifier circuit 16 via signal generating circuit 15. Ports P5 through P7 are connected to the differential-amplifier circuit 16 via a comparative-voltage generating circuit 17. From the differential-amplifier circuit 16 to a port P8, an output VO is supplied which is a deviation between an output VR of circuitry and an output VS of the signal generating circuit 15. The output VS represents the sum or the brightness of light detected by the receiver 5 and the brightness of ambient light. The output VR represents the outputs from the ports P5 through P7 as the brightness of ambient light. Further, an operating panel 18 is connected to ports P1 and P2 so that an output indicative of a closure of a transmissivity setting switch 19 is transmitted to the port P1 and a lamp 20 is turned on or off by an output of the port P2. A port P9 is connected to a RAM 21. Before operation of the present invention is described in detail hereinafter with reference to FIGS. 1 through 8, an outline thereof is described. In order to obtain an optimum amount of light to be emitted from the light-emitter 5 during a sewing operation, the following operation is first performed. That is to say, the transmissivity of the lower cloth and the transmissivity of the upper and lower cloths arranged in a layered configuration are first each calculated 32 times using different amounts of light. Thereafter, a deviation between each transmissivity of the lower cloth and each transmissivity of the upper and lower cloths arranged in a layered configuration at the same amount of light is calculated and the optimum amount of light resulting in a maximum deviation is obtained. Detailed operation of the apparatus according to the present invention next described referring to FIGS. 5-8. When the switch 19 is closed (step S1), a routine for detecting the transmissivity of the lower cloth is executed (step S2). In step S3, a 5-bit flag VSEL to be inputted to the ports P3 through P7 is initialized at 0 and the contents of a register MADR is set to an address VLDAR at which is initially stored the transmissivity of the lower cloth. Thus, initialization is completed. In step S4, the content of the flag VSEL is supplied to ports P3 through P7. In step S5, the transmissivity VO corresponding to the content of the flag VSEL is inputted to a flag A. In step S6, the transmissivity VO is stored in the address VLADR in the resister MA. In step S7, a check is performed whether the flag VSEL is `11111` or not. If not, the flag VSEL is replaced with a next value and an address next to the address VLADR is established in the register MADR. Thereafter, control is returned to step S4. By repeating this operation, at each address in the register MADR, a transmissivity corresponding to a respective value of the flag VSEL is stored. If the contents of the flag is `11111`, the control is returned to the main routine after lighting the lamp 20 in step S9. Thus, all sensitivities VO corresponding to the received lights at the receiver 6 are obtained when the lower cloth is disposed between the emitter 5 and the receiver 6 and are stored in the RAM 21. When the switch 19 is closed in step S10, a routine for detecting the transmissivity of the upper cloth and the lower cloth arranged in layered configuration is performed. In step S12, 5-bit flag VSEL to be inputted to the ports P3 through P7 is initialized at 0 and the contents of the register MADR is set to an address VHADR at which is initially to be stored the transmissivity of the upper cloth arranged in layered configuration with the lower cloth. Thus, initialization is completed. In step S13, the contents of the flag VSEL is supplied to ports P3 through P7. In step S14, the transmissivity VO corresponding to the contents of the flag VSEL is inputted to the flag A. In step S15, the transmissivity VO is stored at the address VHADR in the register MADR. In step S16, a check is performed whether the flag VSEL is `11111` or not. If not, the flag VSEL is replaced with a next value and an address next to the address VHADR is established in the register MADR. Thereafter, the control is returned to step S13. By repeating this operation, in each address in the register MADR, each transmissivity corresponding to each value of the flag VSEL is stored. If the flag is `11111`, the control is returned to main routine. Thus, all sensitivities VO corresponding to the received light at the receiver 6 are obtained when the upper cloth arranged in a layered configuration with the lower cloth is also disposed between the emitter 5 and the receiver 6 and are stored in the RAM 21. At step S18, a routine for setting the sensitivity begins. In step 19, a minimum differential-sensitivity is set. In step S20, the 5-bit flag VSEL is initialized at 0, the first address VHADR of the memory at which the transmissivity of the layered upper cloth is stored is moved to the register MHADR and the first address VLADR of the memory at which the transmissivity of the lower cloth is stored is moved to the register MLADR. Thus, the initialization is completed. In step S21, a differential-transmissivity between the transmissivity of the layered upper cloth and the transmissivity of the lower cloth is calculated and is stored in the flag A. In step S22, a check is performed whether or not the resulting differential-transmissivity in the flag A is greater than the contents of the flag B. If so, in step S23, the contents of the flag B is replaced with that of the flag A and the contents of the flag VSEL is inputted in the flag C. Step S24 is performed when the result of step S22 is negative or the performance of step S23 is completed in such a manner that the flag VSEL is checked to be `1111` or not. If not, step S25, the flag VSEL is replaced with the next value, a new address next to VHADR (VLADR) is established in the register MHADR (MLADR) and the control is returned to step S21. By repeating this operation, a maximum differential-transmissivity is obtained and is inputted into the flag B. In the case where the flag VSEL is `11111`, a check is performed in step S26 to determine whether or not the value of the flag B is greater than the minimum-transmissivity VMIN. If not, an error indication is established in step S27. If so, the mid value of the differential-transmissivity calculated in step S28 is stored in the flag VTH. In step S29, the lamp 20 is lit. As apparent from the above-mentioned description, the sensing ability of the sensor means 3 can be set at an optimum condition wherein the differential-transmissivity is at a maximum condition and the sensor means 3 can operate regardless of the thickness or color of each cloth. In a case where the sewing machine S is provided with a light-emitter 5A and a light-receiver 6A in addition to the light-emitter 5 and the receiver 6 as shown in FIGS. 9 through 11, the above-mentioned procedure is performed for each light-emitter. That is to say, when a switch 22 connects the light-emitter 5 (the light-emitter 5A) to the circuit 13 and the light-receiver 6 (light-emitter 6A) to the circuit 15 according to a signal in the form of `0` (`1`) from a port 10, the above-mentioned procedure is performed for the light-emitter 5 (the light-emitter 5A). The change of the signal from the port 10 is a result of the operation of a switch 90. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings, it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.	An apparatus for detecting a stepped portion between an upper cloth and a lower cloth on which the upper cloth is mounted, including a light-emitter for transmitting light to a light receiver. The stepped portion is detected based on a decrease in light received by the light receiver. In order to assure detection of the stepped portion, an optimum amount of light to be emitted from the light-emitter is determined so that a deviation between a transmissivity of the lower cloth and a transmissivity of both cloths arranged in a layered configuration may be maximized.	3
CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation of U.S. application Ser. No. 12/564,807, filed Sep. 22, 2009, now abandoned which is a continuation of U.S. application Ser. No. 12/114,416, filed May 2, 2008, now abandoned which is a continuation of U.S. application Ser. No. 11/314,630, filed Dec. 21, 2005, now U.S. Pat. No. 7,398,665, which is a continuation of U.S. application Ser. No. 10/182,643, filed Sep. 30, 2002, now U.S. Pat. No. 7,003,999, all of which are related to PCT Application No. PCT/GB01/00526, filed Feb. 9, 2001, G.B. Application No. 0003033.8, filed Feb. 10, 2000, and G.B. Application No. 0026325.1, filed Oct. 27, 2000, all of which are incorporated herein by reference in their entireties. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to deformation of generally thin walled bodies, particularly thin walled containers or tube-form bodies which may be of cylindrical or other form. The invention is particularly suited to embossing of thin walled metallic bodies (particularly aluminium containers) by embossing or the like. More specifically the invention may be used in processes such as registered embossing of thin walled bodies, particularly registered embossing of containers having pre-applied (pre-printed) surface decoration. 2. State of the Art It is known to be desirable to deform by embossing or the like the external cylindrical walls of metallic containers such as aluminium containers. In particular attempts have been made to emboss the walls of containers at predetermined locations to complement a printed design on the external surface of such a container. In such techniques it is important to coordinate the embossing tooling with the preprinted design on the container wall. Prior art proposals disclose the use of a scanning system to identify the position of the container relative to a datum position and reorientation of the container to conform to the datum position. Prior art embossing techniques and apparatus are disclosed in, for example, WO-A-9803280, WO-A-9803279, WO-A-9721505 and WO-A-9515227. Commonly in such techniques the container is loaded into an internal tool which acts to support the container and also co-operate with an external tool in order to effect embossing. Such systems have disadvantages, as will become apparent from the following. SUMMARY OF THE INVENTION An improved technique has now been devised. According to a first aspect, the present invention provides a method of deforming a thin walled body, the method comprising: i) holding the body gripped securely at a holding station; ii) engaging tooling to deform the wall of the body at a predetermined wall zone, the tooling being provided at a tooling station which is adjacent the holding station during deformation; wherein the predetermined wall zone is co-aligned with the tooling by means of co-ordinated movement of the tooling prior to deforming engagement with the wall of the body. According to a further aspect, the invention provides apparatus for deforming a thin walled body, the apparatus including: i) a holding station for holding the body gripped securely; ii) a tooling station including tooling to deform the body at a predetermined wall zone of the body, the tooling station being positioned at a location adjacent the holding station during deformation; iii) determination means for determining the orientation of the cylindrical body relative to a reference (datum) situation; iv) means for co-ordinated movement to reconfigure the tooling to co-align with the predetermined wall zone prior to deforming engagement of the tooling with the body. Co-alignment of the tooling and the wall zone of the body is typically required in order to ensure that embossing deformation accurately lines up with pre-printed decoration on the body. In the technique of the present invention, the body is not passed from being supported at a holding station to being supported by the tooling but, by contrast, remains supported at the holding station throughout the deforming process. Re-configuration of the tooling avoids the requirement for the or each holding or clamping station to have the facility to re-orientate a respective body. The technique is particularly suited to embossing containers having wall thicknesses (t) in the range 0.25 mm to 0.8 mm (particularly in the range 0.35 mm to 0.6 mm). The technique is applicable to containers of aluminium including alloys, steel, tinplate steel, internally polymer laminated or lacquered metallic containers, or containers of other materials. Typically the containers will be cylindrical and the deformed embossed zone will be co-ordinated with a pre-printed/pre-applied design on the circumferential walls. Typical diameters of containers with which the invention is concerned will be in the range 35 mm to 74 mm although containers of diameters outside this range are also susceptible to the invention. Beneficially the tooling will be re-configurable by rotation of the tooling about a rotational tooling axis to co-align with the predetermined wall zone. The determination means preferably dictates the operation of the tooling rotation means to move/rotate the tooling to the datum position. The determination means preferably determines a shortest rotational path (clockwise or anti-clockwise) to the datum position and triggers rotation of the tooling in the appropriate sense. The length of time available to perform the steps of re-orientation and deformation is relatively short for typical production runs which may process bodies at speeds of up to 200 containers per minute. Re-orientation of the tooling (particularly by rotation of the tooling about an axis) enables the desired re-orientation to be achieved in the limited time available. The facility to re-orientate clockwise or anti-clockwise following sensing of the container orientation and shortest route to the datum position is particularly advantageous in achieving the process duration times required. According to a further aspect, the invention provides apparatus for use in deforming a wall zone of a thin walled container, the apparatus comprising internal tooling to be positioned internally of the container, and external tooling to be positioned externally of the container, the external and internal tooling co-operating in a forming operation to deform the wall zone of the container, the internal tooling being moveable toward and away from the centreline or axis of the container between a retraction/insertion tooling configuration in which the internal tool can be inserted or retracted from the interior of the container, to a wall engaging configuration for effecting deforming of the wall zone. Correspondingly a further aspect of the invention provides a method of deforming a thin walled container, the method comprising: inserting internal tooling into the interior of the container, the internal tooling being in a first, insertion configuration for insertion; moving the tooling to a second, (preferably expanded) position or configuration closely adjacent or engaging the internal container wall so as to facilitate deformation of a wall zone of the container; returning the tooling from the second position toward the first tooling configuration thereby to permit retraction of the internal tooling from the container. Because the internal tooling is movable toward and away from the container wall (preferably toward and away from the axis/centreline of the container), embossed relief features of greater depth/height can be produced. This is because prior art techniques generally use an internal tool which also serves to hold the container during deformation (embossing) and therefore typically only slight clearance between the internal tool diameter and the internal diameter of the container has been the standard practice. In accordance with the broadest aspect of the invention, the relief pattern for embossing may be carried on cam portions of internal and/or external tools, the eccentric rotation causing the cam portions to matingly emboss the relevant portion of the container wall. A particular benefit of the present invention is that it enables a greater area of the container wall (greater dimension in the circumferential direction) to be embossed than is possible with prior art techniques where the emboss design would need to be present on a smaller area of the tool. Rotating/cam-form tooling, for example, has the disadvantage of having only a small potential area for design embossing. Re-configurable, particularly collapsible/expandable internal tooling provides that greater depth/height embossing formations can be provided, the internal tooling being collapsed from engagement with the embossed zone and subsequently retracted axially from the interior of the container. Embossed feature depth/height dimensions in the range 0.5 mm and above (even 0.6 mm to 1.2 mm and above) are possible which have not been achievable with prior art techniques. According to a further aspect, the invention provides apparatus for use in deforming the cylindrical wall of a thin walled cylindrical container, the apparatus comprising an internal tooling part to be positioned internally of the container, and an external tooling part to be positioned externally of the container, the external and internal tools co-operating in a forming operation to deform a portion of the cylindrical container wall therebetween; wherein tooling actuation means is provided such that: (a) the external and internal tools are movable independently of one another to deform the container wall; and/or (b) deforming force applied to the external and internal tools is positioned at force action zones spaced at opposed sides of the zone of the container wall to be deformed. As described above, the technique of the invention is particularly suited to embossing containers having relatively thick wall thickness dimensions (for example in the range 0.35 mm to 0.8 mm). Such thick walled cans are suitable for containing pressurised aerosol consumable products stored at relatively high pressures. Prior art techniques have not been found to be suitable to successfully emboss such thicker containers, nor to produce the aesthetically pleasing larger dimensioned emboss features as is capable with the present invention (typically in the range 0.3 mm to 1.2 mm depth/height). The technique has also made it possible to emboss containers (such as seamless monobloc aluminium containers) provided with protective/anti-corrosive internal coatings or layers without damage to the internal coating or layer. According to a further aspect, the invention therefore provides an embossed container or tube-form product, the product comprising a product side-wall having a thickness substantially in the range 0.25 mm to 0.8 mm and a registered embossed wall zone, the embossed deformation having an emboss form depth/height dimension substantially in the range 0.3 mm to 1.2 mm or above. Preferred features of the invention are defined in the appended claims and readily apparent from the following description. The various features identified and defined as separate aspects herein are also mutually beneficial and may be beneficially included in combination with one another. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described in a specific embodiment, by way of example only, and with reference to the accompanying drawings, in which: FIG. 1 is a flow diagram of a process according to the invention; FIG. 2 is a view of a container to be operated upon in accordance with the invention; FIG. 3 is a side view of the container of FIG. 2 in a finish formed state; FIG. 4 is a 360 degree view of a positional code in accordance with the invention; FIG. 5 is a schematic side view of apparatus in accordance with the invention; FIGS. 6 and 7 are half plan views of apparatus components of FIG. 5 ; FIGS. 8 , 9 and 10 correspond to the views of FIGS. 5 , 6 and 7 with components in a different operational orientation; FIG. 11 is a schematic close up sectional view of the apparatus of the preceding figures in a first stage of the forming process; FIG. 11 a is a detail view of the forming tools and the container wall in the stage of operation of FIG. 11 ; FIGS. 12 , 12 a to 16 , 16 a correspond to the views of FIGS. 11 and 11 a ; and FIG. 17 is a schematic sectional view of an embossed zone of a container wall in accordance with the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings the apparatus and technique is directed to plastically deforming (embossing or debossing) the circumferential wall of an aluminium container 1 at a predetermined position relative to a preprinted decorative design on the external container wall. Where the embossing deformation is intended to coincide with the printed decorative design, this is referred to in the art as Registered Embossing. In the embodiment shown in the drawings, a design 50 comprising a series of three axially spaced arc grooves is to be embossed at 180 degree opposed locations on the container wall (see FIG. 16 a ). For aesthetic reasons it is important that the location at which the design 50 is embossed is coordinated with the printed design on the container 1 wall. Coordination of the container 1 axial orientation with the tooling to effect deformation is therefore crucial. Referring to FIGS. 5 to 7 the forming apparatus 2 comprises a vertically orientated rotary table 3 operated to rotate (about a horizontal axis) in an indexed fashion to successively rotationally advanced locations. Spaced around the periphery of table 3 are a series of container holding stations comprising clamping chucks 4 . Containers are delivered in sequence to the table in random axial orientations, each being received in a respective chuck 4 , securely clamped about the container base 5 . A vertically orientated forming table 6 faces the rotary table 3 and carries a series of deformation tools at spaced tooling stations 7 . Following successive rotary index movements of rotary table 3 , table 6 is advanced from a retracted position ( FIG. 5 ) to an advanced position ( FIG. 8 ). In moving to the advanced position the respective tools at tooling stations 7 perform forming operations on the container circumferential walls proximate their respective open ends 8 . Successive tooling stations 7 perform successive degrees of deformation in the process. This process is well known and used in the prior art and is frequently known as necking. Necked designs of various neck/shoulder profiles such as that shown in FIG. 3 can be produced. Necking apparatus typically operates at speeds of up to 200 containers per minute giving a typical working time duration at each forming station in the order of 0.3 seconds. In this time, it is required that the tooling table 6 moves axially to the advanced position, the tooling at a respective station contacts a respective container and deforms one stage in the necking process, and the tooling table 6 is retracted. In accordance with the invention, in addition to the necking/shoulder-forming tooling at stations 7 , the tooling table carries embossing tooling 10 at an embossing station 9 . The embossing tooling (shown most clearly in FIGS. 11 to 16 ) comprises inner forming tool parts 11 a , 11 b of respective arms 11 of an expandible internal tool mandrel 15 . Tool parts 11 a , 11 b carry respective female embossing formations 12 . The embossing tooling 10 also includes a respective outer tool arrangement including respective arms 13 carrying tooling parts 13 a , 13 b having complementary male embossing formations 14 . In moving to the table 7 advanced position the respective internal tool parts 11 a , 11 b are positioned internally of the container spaced adjacently the container 1 wall; the respective external tool parts 13 a , 13 b are positioned externally of the container spaced adjacently the container 1 wall. The internal mandrel 15 is expandible to move the tooling parts 11 a , 11 b to a relatively spaced apart position in which they abut the internal wall of the container 1 (see FIG. 12 ) from the collapsed position shown in FIG. 11 (tools 11 a , 11 b spaced from the internal wall of the container 1 ). An elongate actuator rod 16 is movable in a longitudinal direction to effect expansion and contraction of the mandrel 15 and consequent movement apart and toward one another of the tool parts 11 a , 11 b . A the cam head portion 17 of the actuator rod 16 effects expansion of the mandrel 15 as the actuator rod 16 moves in the direction of arrow A. The cam head portion 17 acts against sloping wedge surfaces 65 of the tool parts 11 a , 11 b to cause expansion (moving apart) of the tool parts 11 a , 11 b . The resilience of arms 11 biases the mandrel 15 to the closed position as the rod 16 moves in the direction of arrow B. Outer tool arms 13 are movable toward and away from one another under the influence of closing cam arms 20 of actuator 21 acting on a cam shoulder 13 c of respective arms 13 . Movement of actuator 21 in the direction of arrow D causes the external tooling parts 13 a to be drawn toward one another. Movement of actuator 21 in the direction of arrow E causes the external tool parts 13 a to relatively separate. Arms 13 and 11 of the outer tool arrangement and the inner mandrel are retained by cam support ring 22 . The arms 11 , 13 resiliently flex relative to the support ring 22 as the actuators 21 , 16 operate. As an alternative to the cam/wedge actuation arrangement, other actuators may be used such as hydraulic/pneumatic, electromagnetic (e.g. solenoid actuators) electrical (servo/stepping) motors. The operation of the embossing tooling is such that the internal mandrel 15 is operable to expand and contract independently of the operation of the external tool parts 13 a. The internal mandrel 15 (comprising arms 11 ) and the external tooling (comprising arms 13 ) connected at cam support ring 22 , are rotatable relative to table 6 , in unison about the axis of mandrel 15 . Bearings 25 are provided for this purpose. A servo-motor (or stepping motor) 26 is connected via appropriate gearing to effect controlled rotation of the tooling 10 relative to table 6 in a manner that will be explained in detail later. With the tooling 10 in the position shown in FIG. 11 , the mandrel 15 is expanded by moving actuator rod 16 in the direction of arrow A causing the internal tooling parts 11 a to lie against the internal circumferential wall of cylinder 1 , adopting the configuration shown in FIGS. 12 , 12 a . Next actuator 21 moves in the direction of arrow D causing cam arms 20 to act on cam shoulder 13 c and flexing arms 13 toward one another. In so doing the external tooling parts 13 a engage the cylindrical wall of container 1 , projections 14 deforming the material of the container 1 wall into respective complementary receiving formations 12 on the internal tooling parts 11 a. The deforming tooling parts 11 a , 13 a , can be hard, tool steel components or formed of other materials. In certain embodiments one or other of the tooling parts may comprise a conformable material such as plastics, polymeric material or the like. An important feature is that the internal tooling parts 11 a support the non deforming parts of the container wall during deformation to form the embossed pattern 50 . At this stage in the procedure, the situation is as shown in FIGS. 13 , 13 a . The configuration and arrangement of the cam arms 20 , cam shoulders 13 c of the external embossing tooling and the sloping (or wedge) cam surface of internal tooling parts 11 a (cooperating with the cam head 17 of rod 16 ) provide that the embossing force characteristics of the arrangement can be controlled to ensure even embossing over the entire area of the embossed pattern 50 . The external cam force action on the outer tool parts 13 a is rearward of the embossing formations 14 ; the internal cam force action on the inner tool parts 11 a is forward of the embossing formations 12 . The forces balance out to provide a final embossed pattern of consistent depth formations over the entire zone of the embossed pattern 50 . Next actuator 21 returns to its start position (arrow E) permitting the arms 13 of the external tooling to flex outwardly to their normal position. In so doing tooling parts 13 a disengage from embossing engagement with the container 1 external surface. At this stage in the procedure, the situation is as shown in FIGS. 14 , 14 a. The next stage in the procedure is for the internal mandrel to collapse moving tooling parts 11 a out of abutment with the internal wall of the cylinder 1 . At this stage in the procedure, the situation is as shown in FIGS. 15 , 15 a. Finally the tooling table 6 is retracted away from the rotatable table 3 withdrawing the tooling 10 from the container. At this stage in the procedure, the situation is as shown in FIGS. 16 , 16 a. In the embodiment described, the movement of the tools to effect embossing is translational only. It is however feasible to utilise rotational external/internal embossing tooling as is known generally in the prior art. The rotary table is then indexed rotationally moving the embossed container to adjacent with the next tooling station 7 , and bringing a fresh container into alignment with the embossing tooling 10 at station 9 . The embossing stages described correspond to stages 106 to 112 in the flow diagram of FIG. 1 . Prior to the approachment of the embossing tooling 10 to a container 1 clamped at table 3 ( FIG. 11 and stage 106 of FIG. 1 ) it is important that the container 1 and tooling 10 are accurately rotationally oriented to ensure that the embossed pattern 50 is accurately positioned with respect to the printed design on the exterior of the container. According to the present invention this is conveniently achieved by reviewing the position of a respective container 1 whilst already securely clamped in a chuck 4 of the rotary table 3 , and rotationally reorientating the embossing tooling 10 to the required position. This technique is particularly convenient and advantageous because a rotational drive of one arrangement (the embossing tooling 10 ) only is required. Chucks 4 can be fixed relative to the table 3 and receive containers in random axial rotational orientations. Moving parts for the apparatus are therefore minimised in number, and reliability of the apparatus is optimised. The open ends 8 of undeformed containers 1 approaching the apparatus 2 have margins 30 printed with a coded marking band 31 comprising a series of spaced code blocks or strings 32 (shown most clearly in FIG. 4 ). Each code block/string 32 comprises a column of six data point zones coloured dark or light according to a predetermined sequence. With the container 1 clamped in random orientation in a respective chuck 4 a charge coupled device (CCD) camera 60 views a portion of the code in its field of view. The data corresponding to the viewed code is compared with the data stored in a memory (of controller 70 ) for the coded band and the position of the can relative to a datum position is ascertained. The degree of rotational realignment required for the embossing tooling 10 to conform to the datum for the respective container is stored in the memory of main apparatus controller 70 . When the respective container 10 is indexed to face the embossing tooling 10 the controller instigates rotational repositioning of the tooling 10 to ensure that embossing occurs at the correct zone on the circumferential surface of the container 1 . The controller 70 when assessing the angular position of the tooling relative to the angular position to be embossed on the container utilises a decision making routine to decide whether clockwise or counterclockwise rotation of the tooling 10 provides the shortest route to the datum position, and initiates the required sense of rotation of servo-motor 26 accordingly. This is an important feature of the system in enabling rotation of the tooling to be effected in a short enough time-frame to be accommodated within the indexing interval of the rotating table 3 . The coding block 32 system is in effect a binary code and provides that the CCD camera device can accurately and clearly read the code and determine the position of the container relative to the tooling 10 datum by viewing a small proportion of the code only (for example two adjacent blocks 32 can have a large number of unique coded configurations). The coding blocks 32 are made up of vertical data point strings (perpendicular to the direction of extent of the coding band 31 ) in each of which there are dark and light data point zones (squares). Each vertical block 32 contains six data point zones. This arrangement has benefits over a conventional bar code arrangement, particularly in an industrial environment where there may be variation in light intensity, mechanical vibrations and like. As can be seen in FIG. 4 , because the tooling 10 in the exemplary embodiment is arranged to emboss the same pattern at 180 degree spacing, the coding band 31 includes a coding block pattern that repeats over 180 degree spans. The position determination system and control of rotation of the tooling 10 are represented in blocks 102 to 105 of the flow diagram of FIG. 1 . The coding band 31 can be conveniently printed contemporaneously with the printing of the design on the exterior of the container. Forming of the neck to produce, for example a valve seat 39 ( FIG. 3 ) obscures the coding band from view in the finished product. As an alternative to the optical, panoramic visual sensing of the coding band 31 , a less preferred technique could be to use an alternative visual mark, or a physical mark (e.g. a deformation in the container wall) to be physically sensed. Referring to FIG. 17 , the technique is particularly switched to forming aesthetically pleasing embossed formations 50 of a greater height/depth dimension (d) (typically in the range 0.3 mm to 1.2 mm) than has been possible with prior art techniques. Additionally, this is possible with containers of greater wall thickness (t) than have been successfully embossed in the past. Prior art techniques have been successful in embossing aluminium material containers of wall thickness 0.075 mm to 0.15 mm. The present technique is capable of embossing aluminium containers of wall thickness above 0.15 mm, for example even in the range 0.25 mm to 0.8 mm. The technique is therefore capable of producing embossed containers for pressurised aerosol dispensed consumer products which has not been possible with prior art techniques. Embossed monobloc seamless aluminium material containers are particularly preferred for such pressurised aerosol dispensed products (typically having a delicate internal anti-corrosive coating or layer protecting the container material from the consumer product). The present invention enables such containers to be embossed (particularly registered embossed). As an alternative to the technique described above in which the embossing tooling is rotated to conform to the datum situation, immediately prior to the container being placed in the chuck 4 and secured, the position of the container may be optically viewed to determine its orientation relative to the datum situation. If the orientation of the container 1 differs from the desired datum pre-set situation programmed into the system, then the container is rotated automatically about its longitudinal axis to bring the container 1 into the pre-set datum position. With the container in the required datum position, the container is inserted automatically into the clamp 4 of the holding station, and clamped securely. In this way the relative circumferential position of the printed design on the container wall, and the position of the tooling is co-ordinated. There is, thereafter, no requirement to adjust the relative position of the container and tooling. This technique is however less preferred than the technique primarily described herein in which the embossing tooling 10 is re-orientated. The invention has primarily been described with respect to embossing aluminium containers of relatively thin wall thicknesses (typically substantially in the range 0.25 mm to 0.8 mm. It will however be readily apparent to those skilled in the art that the essence of the invention will be applicable to embossing thin walled containers/bodies of other material such as steel, steel tinplate, lacquered plasticised metallic container materials an other non-ferrous or non-metallic materials.	A thin walled body is deformed in a process in which the body is gripped securely in a holding station and, while gripped in the holding station, tooling engages to deform the peripheral wall of the body at a predetermined wall zone. The tooling is provided at a tooling station which is adjacent the holding station during deformation. The predetermined wall zone is co-aligned with the tooling by rotation of the body about an axis prior to securing at the holding station.	8
PRIORITY CLAIM This application claims priority to U.S. Utility patent application Ser. No. 11/155,951, filed Jun. 15, 2005, and U.S. Provisional Application No. 60/580,428 filed Jun. 17, 2004. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to construction templates. More specifically, the present invention relates to a mobile construction template for creating large segments of structural lattice framework that is used in warehouses that store barrels. 2. Background Support frames have long been used for supporting barrels of distilled spirits that are aged at wineries and distilleries. The interconnected lattice-work creates support racks on which rows of barrels are placed. This lattice-work has to be exceptionally strong as often several stories of racks are contained in each warehouse for housing thousands of barrels, each barrel weighing hundreds of pounds. The barrel racks must enable the barrels to be stored in an organized fashion, due to the need periodic relocation of each barrel during the ageing period, and to provide ultimately for removal of the barrels from the warehouse. It is well-known in the art that a certain amount of airflow is necessary between the barrels to promote proper maturation of the spirits and that uniformity of the racks will aid in maintenance of the desired airflow. Also, the supporting framework of these barrel racks is constructed using a series of almost identical segments of post and beam frames, that run parallel and that are stacked one frame upon another inside a warehouse. A common method of constructing lattice-work is through the use of skilled carpenters inside the barrel warehouse. Each piece of the lumber used to make barrel support structures would be cut and assembled piece by piece inside the warehouse. To accelerate the construction, a need exists for a mobile construction template. The prior art methods for hand-assembling the lattice-work did result in the racks being constructed in proper form, but the costs were high due to the wasted materials, hours of labor, and the need for carpenters with the requisite skills in the method. Wasted materials result from the individual construction of each element of the lattice-work, from sawing off the vertical support members, to fit and provide attachment to the horizontal barrel support members. Hours of hand labor were spent to orient and manually assemble the components of the lattice-work. Furthermore, skilled construction laborers are required since proper sizing and fit of each rack is necessary to achieve a level rack with the desired rack spacing, which allows for the periodic rotation and relocation of the barrels. In addition, when expansion of an existing warehouse is desired, the skilled labor force would have to work within the temperature and humidity conditions within the warehouse. The present invention provides a construction template system designed to create full lattice segments on a mobile unit, which enables the construction of support frame and their placement for use in barrel warehouses, thereby reducing the production inefficiencies experienced through manual construction, and assembly inside a barrel warehouse. BRIEF SUMMARY OF THE INVENTION The present invention is directed toward a system for the efficient production of lattice-work for storing barrels in a barrel warehouse. The construction template of the present invention comprises a combination different components used together in an effective manner. The lattice construction system is based off of a mobile trailer allowing for relocation of the system near the work site, such as where a warehouse is being built or expanded. On the main bed are a multitude of near vertical members extending upward and along the length of the main bed, spaced parallel and equidistant. Each vertical member has a series of tabs extending near horizontally, which function in both stabilizing the vertical beams of the lattice segment and also in correctly positioning the barrel support beams for proper attachment of the vertical beams to the horizontal barrel support beams. The described invention alleviates many of the problems associated with construction of lattice-work for supporting barrels full of spirits. One of the largest advantages of the lattice construction system is the correct orientation of each beam; the vertical members and extending tabs mandate proper height, spread, and angle of the lattice. This template system minimizes common construction errors by individual laborers working on a barrel warehouse. Additionally, in the case of a barrel warehouse expansion, less disruption is caused to the preexisting storage areas. Finally, the lattice construction system is mobile; the system can be also be used directly outside the barrel warehouse or in a remote location where construction may be more practical. BRIEF DESCRIPTION OF THE DRAWINGS The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: FIG. 1 is a detailed front view of one embodiment of a lattice construction system; FIG. 2 is a side view of one embodiment of a lattice construction system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS While the present invention will be described more fully hereinafter with reference to the accompanying drawings in which particular embodiments and methods are shown, it is to be understood from the outset that persons of ordinary skill in the art may modify the mobile construction template herein described and achieve the functions and results of this invention. Accordingly, the description is to be understood as illustrative and exemplary of workable embodiments within the broad scope of the invention, and not as limiting its scope. In the following descriptions, like numbers refer to similar features or like elements throughout. Referring now to FIG. 1 , a front total view of an embodiment of a lattice construction system is shown. Affixed on a typical truck-drawn trailer 100 , or equivalent mobile unit, is the main horizontal bed 110 . The horizontal bed 110 provides structural integrity to the lattice construction system, and also offers an ideal walkway for laborers using the system. A plurality of vertical beam positioning members commonly designated at 120 are mounted onto the main horizontal bed 110 and extend upward. The vertical support beams of the lattice structure are positioned in contact with each vertical beam positioning member 120 . In the preferred embodiment, these vertical beam positioning members are not mounted vertically on the bed, but rather are in a tilted position. The tilting of these members 120 allows the workpiece beam to be laid against the positioning member so that the beam rests back against the member 120 and remains in that location while the further steps and parts are being worked with. The vertical beams may be cut to the desired length while in place against the positioning member, or precut to a predetermined length before being placed against the vertical positioning member. In that manner, the positioning member serves as a template for the vertical beam to be cut to the predetermined length, and as a template to locate the point at which the vertical beams will be joined to the horizontal beams to form a segment of the barrel support lattice. Extending, perpendicularly outward, from the vertical beam positioning members 120 are position maintenance tabs 130 . The purpose of these tabs is to provide a support or rest for the horizontal beam members that will be joined to the vertical beams. The position maintenance tabs 130 maintain the position of the vertical support beams that form the lattice structure, and the tabs minimize lateral movement. In one preferred embodiment, the tabs are connected along the side of the vertical positioning member, and in other embodiments, the tabs are adjacent to those members. The position maintenance tabs 130 are positioned in an identical vertical arrangement on each respective vertical beam positioning member 120 so that the lowest position maintenance tab 130 of each vertical beam positioning member 120 is the exact distance above the main horizontal bed 110 as are each of the other lowest position maintenance tabs 130 on the other vertical beam positioning members 120 . So too, the distance between each of the vertical beam positioning members 120 is the same, across the bed. In the preferred embodiment, each vertical positioning member has a pair of maintenance tabs, starting with a first pair near the lower end of the member, and the desired number of pairs placed above that first pair. In that manner, the tabs are located at an equal, predetermined distance on the vertical beam positioning members 120 . The horizontal beams may be cut to the desired length while in place on the maintenance tabs, or precut to a predetermined length before being placed on the tabs. These elements provide a template for joining the horizontal beam resting on the tabs to the vertical beam on the positioning member. Post clamps 140 secure each vertical support beam and square the beam in tight contact with each vertical beam positioning member. The claims may be adjustable so that they can be used to hold the horizontal beams in place as well. The post clamps may be clamps that are manually tighten, or in other embodiments, the securing hardware may secure using friction against the beam or may gouge the wooden beam. In one preferred embodiment, the clamp mechanism slides along the vertical positioning member such that it is moved up or down to contact the beam or beam near the point where the vertical beam and horizontal beam are to be joined. A further utilitarian feature of the mobile unit provide electrical power along the bed of the platform, with the preferred embodiment having an electrical conduit 160 that runs behind the vertical beam positioning members 130 in a zig-zag fashion. Finally, stability beams 170 run horizontally, attached to the rear side of the vertical support position members 120 providing strength and stability to the lattice construction system. By this method of joining upright members to cross beams, to form a matrix of beams joined at its interstices with hardware typical of such construction, results in large frames to support barrels being made more efficiently. FIG. 2 . illustrates a side view of the same embodiment of the lattice construction system. From this angle, the fold-down walkway 200 is visible, providing an area behind the vertical beam positioning members 120 for laborers to traverse. Further disclosed is an embodiment of the lattice construction system with containment bins 300 . These bins can be used to store tools, attachment materials, and other various supplies for operation of the lattice construction system. The electrical connections 160 provide easy accessibility for any tools that require electrical power. The mobile apparatus is taken to the desired location, and the components of the construction template are erected on the bed of the trailer, which has prepositioning footings in the bed or slots 112 therethrough, which accept the lower end of the vertical positioning member. With this embodiment, vertical support beams of the lattice structure are placed in contact with each respective vertical beam positioning member 120 , and in between the sets of position maintenance tabs 130 , which in the preferred embodiment extend from each vertical beam positioning member 120 . Also, in one preferred embodiment, each vertical beam positioning member 120 is comprised of two, parallel metal struts 120 A and 120 B, and the distance between those struts is adequate for the vertical beam to be placed between them. In this embodiment, the struts act as a template to align the vertical beam in perpendicular relation to the barrel support beams to which the vertical beams are joined to form a segment of the support frame for the barrels. In the working arrangement, the lower end of the vertical beam is placed in a footing 121 at the base of the vertical beam positioning member 120 , on the trailer-mounted bed, and laid back in alignment with the struts on that member. As the work progresses, vertical beams are placed against each of the vertical beam positioning members. The barrel support beams are positioned horizontally, resting up the position maintenance tabs 130 . In this manner, the barrel support beams extend across the construction template, at an uniform height, and in contact with each vertical support beam. Once the beams are in place, the post clamps are secured over, to, or around the beams, which minimizes movement of the beams as they are joined. The barrel support beams and vertical support beams can then be fixed together at their various intersections by either brackets, long nails or other suitable joining hardware, or suitable construction adhesives. Thus, the lattice construction system created a segment of a lattice-work with beams meeting perfectly at perpendicular angles with each beam in a position and with spacing predetermined by the template of the lattice construction system. For the installation of the lattice segments in the barrel warehouse, the completed support segments are either carried off the trailer 100 to the barrel warehouse site, or when assembled at the construction site, the lattice segments are lifted directly off the trailer by crane slings and lowered into place in the proper orientation within the warehouse being built or expanded. In a typical circumstance, the completed frame is lifted from the trailer-mounted template, and placed on footings in the warehouse, then another frame is lifted onto the frame on the footing, and so forth, until the desired number of levels for barrel storage is reached. The entire lattice construction system is relatively simple but yet highly efficient, requiring few laborers and little maintenance, providing a number of advantages over the manual construction of barrel racks. The lattice construction system can be operated by semi-skilled workers since the system orients the beams at the proper angles and height. The mobile unit provides a work area on the bed 110 , and additionally, the preferred embodiment includes a walkway 200 that extends off the bed. This walkway enables workers to work from both sides of the template, which is useful to placing and joining the beams. In working arrangement, workers on one side of the bed will pass the beams to workers on the bed, who will place those on the template, and then workers on the bed and the walkway will affix the joining hardware. The support segments can be constructed outside of the warehouse and subsequently installed, allowing for much less construction time inside the warehouse. All that is necessary is the proper securing of the segment in the warehouse. The mobile lattice construction system can be utilized away from the warehouses in hilly or confined places, at a better construction location. With those barrel warehouses located on hilltops, the lattice construction system eliminates the need to construct barrel racks in non-ideal locations. One preferred embodiment of the invention is a construction template comprising: a movable platform, a plurality of positioning members mounted generally upright on said platform, each said member being mounted parallel to, and equidistant from the adjacent members, each said positioning member having an upper and a lower end, a plurality of position maintenance tabs on each said positioning member, said tabs extending outwardly from said member, with a first tab near the lower end of said member, then a second tab above said first tab and equidistant therefrom, a plurality of beam clamps attached to each said positioning member, to releasably secure a beam in horizontal relation to said upright positioning members. In a variation of the construction template based on that preferred embodiment, the movable platform comprises a flat bed trailer for being moved by a motorized vehicle. Further, in another variation of the construction template based on that preferred embodiment, each positioning member is mounted approximately ten degrees off of vertically upright on said platform. In another variation of the construction template based on that preferred embodiment, each positioning member comprises two parallel struts set apart at a distance predetermined to accept a beam. With another variation of the construction template based on that preferred embodiment, each positioning member comprises two parallel struts set apart at a distance predetermined to accept a beam, and at predetermined points, a pair of said maintenance position tabs are attached to the pair of struts. In another variation of the construction template based on that preferred embodiment, each beam clamp comprises an extendable beam gripper and adjustable securing hardware for the gripper. Another preferred embodiment of the invention is a construction template comprising: a movable platform, a plurality of lateral positioning members or means mounted generally upright on said platform, each said member being mounted parallel to, and equidistant laterally from the adjacent members, each said positioning member having an upper and a lower end, a plurality of position maintenance tabs on each said positioning member, said tabs extending outwardly from said member, with a first tab near the lower end of said member, then a second tab above said first tab and equidistant therefrom, a plurality of beam clamps attached to each said positioning member, to support a beam releasably in horizontal relation to said upright positioning members. In a variation of the construction template based on that preferred embodiment, each lateral positioning member is mounted at a predetermined angle off of vertically upright on the platform. Further, in another variation of the construction template based on that preferred embodiment, each lateral positioning member comprises two parallel struts set apart at a distance predetermined to accept a beam, and the distance is predetermined by the length of the beam. In another variation of the construction template based on that preferred embodiment, each lateral positioning member comprises two parallel struts set apart at a distance predetermined to accept a beam, and at predetermined points, a pair of the position maintenance tabs are attached to the pair of struts. With another variation of the construction template based on that preferred embodiment, each beam clamp comprises an extendable beam gripper and adjustable support hardware. The preferred embodiments are useful when the structural elements are utilized as a construction template, and the steps preferred provide a method of assembling barrel support segments using a construction template, comprising: positioning a vertical beam against a vertical beam positioning member of said construction template, placing a horizontal beam upon position maintenance tabs of said construction template, clamping said beams securely for joining, joining said horizontal beam to said vertical beam at a predetermined point, lifting said joined beams from said construction template. Persons of ordinary skill would understand not to practice these steps by another and materially different apparatus or by hand, and would not use the claimed apparatus to practice another and materially different method. A variation of the present invention is a preferred embodiment of a construction template comprising: a movable platform, a plurality of lateral positioning members mounted generally upright on said platform, each said member being mounted parallel to adjacent members to mandate lateral positions and spread between a plurality of beams, each said positioning member having an upper and a lower end, a plurality of position maintenance tabs on each said positioning member, said tabs extending outwardly from said member, with a first tab near the lower end of said member, then a second tab above said first tab and equidistant therefrom, a plurality of beam clamps attached to each said positioning member, to support a beam releasably in horizontal relation to said lateral positioning members.	A construction template mounted on a mobile platform. The template is useful in the assembly of racks made for storing barrels, typically barrels of distilled spirits in a warehouse. Beams that will be joined to form a rack are placed alongside upright positioning elements of the construction template. Beams are placed horizontally held by tabs on the construction template. Then the upright and horizontal beams are joined to form a rack assembly that is lifted and moved off the platform.	1
BACKGROUND OF THE INVENTION The present invention relates to a device for carrying articles with handles and more particularly to a handle assembly capable of carrying a plurality of shopping bags that is fully operable with a single hand. DESCRIPTION OF THE PRIOR ART Supermarkets and retailers use a number of different types of bags to assist the consumer in transporting the purchased goods from the store to the consumer's home. Many of these shopping bags are provided with handle members at the top of the bag for ease in carrying the same. The shopping bags tend to be small in nature, which promotes the desire for the consumer to carry several shopping bags in each hand when traveling from the store to the consumer's car or from the consumer's car into their home. However, as the number of bags carried within one hand increases, along with the varied weight of the goods within the bags, the load becomes increasingly uncomfortable and difficult to carry by the consumer. This typically necessitates multiple trips. Several devices have been developed to assist the consumers in transporting their bagged goods. U.S. Pat. No. 5,855,403 discloses a bag carrying device having elongated, spaced-apart upper and lower portions and a separate carrying handle extending from the upper portion. A resiliently deformable tab member extends between the upper and lower portions of the device in an attempt to retain the articles in the carrying device. While such a device is certainly beneficial in overcoming a number of the difficulties encountered in carrying a plurality of shopping bags, such a design suffers from the inconvenience of being incapable of single-handed operation. The prior art patent discloses no apparent manner of carrying the device by its handle while simultaneously actuating the resilient tab member to engage and release the articles. Accordingly, the user must use both hands to load the articles onto the device and then use both hands to unload the articles. When an individual is using two devices, these additional steps double. Moreover, the resiliently deflectable tab is dependent upon the flexibility from which the handle is formed to provide its available movement. This limits the range of movement of the tab, limits the usable life of the tab's deflection points, and fails to provide any manner of stably securing the tab in a closed or open position. U.S. Pat. No. 5,904,388 discloses another bag carrying device having elongated upper and lower members that are spaced apart from one another. The device is further provided with a latch and hook assembly to retain the articles within the device. The lower portion of the device is provided with a plurality of recesses to receive the handles extending from the articles. However, this device, while adding numerous bells and whistles, suffers from the same deficiencies as the other prior art devices. Nowhere is the device described as being capable of being carried while simultaneously actuating the latch and hook mechanism with the hand that is carrying the device. Moreover, the arrangement of the articles among the various recesses also necessitates the use of a second hand to properly arrange the same. Similarly, U.S. Pat. No. 5,263,755 discloses a bag carrying device that is generally D-shaped, having a hinged lower receiving member that supports the bags in the carrying position. To secure the lower receiving member in position, a pin member extends through the handle and is selectively engageable with the free hand of the lower member. Again, however, this system is incapable of single-handed operation. Moreover, if the lower retaining member were disengaged while the articles were being carried, the entire carrying device would open up and release all of the articles indiscriminately. The curved nature of the lower retaining member further provides for a difficult distribution of the weight of the articles when they are loaded into the device. U.S. Pat. No. 5,433,494 discloses a handle device having recesses disposed at the opposite ends of a gripping member. The recesses are selectively closed using a slidable, horizontally disposed pin member. However, such a device is plagued with the problem of even weight distribution, much like the common teeter-totter. Moreover, due to the fact that the sliding retaining members are positioned at the opposite ends of the handle, the device is not conveniently operable with a single hand while the device is being carried. Accordingly, what is needed is a novel device for carrying articles that is simultaneously operable and carryable with a single hand. SUMMARY OF THE INVENTION The device for carrying articles of the present invention is provided with elongated upper and lower members that are positioned in a generally parallel spaced-apart relationship with one another. The space between the upper and lower members provides a recess in which the handles of shopping bags or other articles can be received. A retaining member is pivotably coupled to the forward end of the upper member and selectively moves between open and closed positions with respect to the lower member. In use, the device can be carried by the upper member while the user simultaneously pivots the retaining member into its open position to receive the shopping bag handles. The user then, with the same hand, closes the retaining member and transports the shopping bags accordingly. At the user's final destination, the retaining member can be pivoted to its open position with the same hand that is carrying the device so that the shopping bags can be selectively released from the device. Accordingly, the device enables a user to use separate devices in the user's right and left hand to quickly and efficiently collect, transport, and release a plurality of shopping bags. A ratchet and pawl system is provided adjacent the pivot connection between the retaining member and the upper member to selectively retain the retaining member in its closed or open positions. A spring member is optionally coupled to the ratchet and pawl assembly to conveniently bias the retaining member to its open position when the user actuates the pawl. A retaining lip is optionally provided at the free end of the retaining member to operatively engage a recess formed in the free end of the lower member to secure the retaining member in its closed position. The lip and recess assembly can be used in conjunction with or apart from the ratchet and pawl assembly. It is therefore a principal objection of the present invention to provide a device for carrying articles having an article retaining assembly that can be actuated while the device is being carried by the same hand carrying the device. A further object of the present invention is to provide a device for carrying articles having a retaining assembly that is selectively lockable in open and/or closed positions. Still another object of the present invention is to provide a device for carrying articles having an article retaining assembly that is easily operable with a single hand. Yet another object of the present invention is to provide a device for carrying articles having an article retaining assembly that is provided with multiple methods of securing the retaining assembly in a closed position. Still another object of the present invention is to provide a device for carrying articles that is durable yet simple to manufacture. These and other objects will be apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of the device of the present invention as the same might be used to carry articles; FIG. 2 is a perspective view of the device for carrying articles of the present invention; FIG. 3 is a side elevation view of the device of FIG. 1 further depicting an embodiment of the article retaining assembly; and FIG. 4 is a partial cutaway view of one embodiment of a method of securing the retaining assembly of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT The numeral 10 refers generally to the shopping bag handle of the present invention, as depicted in FIGS. 1–3 . The shopping bag handle is generally provided with an elongated gripping member 12 having a forward end portion 14 and a rearward end portion 16 . The gripping member 12 is further preferably provided with a lower surface portion 18 having a shape that substantially conforms to the hand of a user. It is contemplated that the shape of the lower surface 18 could be curved or generally parabolic-shaped, as shown in FIG. 1 . It is further contemplated that individual recesses could be formed in the lower surface 18 for the proper location of the user's fingers. To further provide for the comfort of the user, the gripping member 12 could be provided with a layer of deformably resilient material, such as rubber, foam rubber, or other synthetic version thereof, such as Neoprene. The shopping bag handle 10 is further provided with an elongated support member 20 having a forward end portion 22 and a rearward end portion 24 . The support member 20 is preferably positioned in a spaced relationship to the gripping member 12 , as shown in FIG. 1 . It is preferred, although not crucial, that the support member 20 be generally parallel to the gripping member 18 . The rearward end portion 24 preferably extends upwardly towards and connects with the rearward end portion 16 of the gripping member 12 to form a rearward side member 26 of the shopping bag handle 10 . However, it is contemplated that a separate structure could be provided for coupling the gripping member 12 to the support member 20 at their respective rearward end portions 16 and 24 . It is contemplated that the gripping member 12 and support member 20 could be formed from nearly any material such as wood, metal or plastic. However, it is preferred for the cost and practicality of manufacture that the component parts be manufactured from plastic. As can be seen in FIG. 1 , support member 20 may be optionally formed to have an I-shaped cross section to provide an improved strength to weight ratio over other comparable designs. However, it is contemplated that the support member 20 could be formed as a hollow tube-shaped member or from a solid material in nearly any shape that is commercially feasible. A retaining assembly is preferably provided to the shopping bag handle 10 , comprising at least a retaining member 28 having an upper end portion 30 and a lower end portion 32 . The upper end portion 30 of the retaining member 28 is preferably pivotably coupled to the forward end portion 14 of the gripping member 12 so that the retaining member 28 is selectively movable between open and closed positions, as shown in FIG. 2 . The retaining member 28 preferably has a length sufficient to position its lower end 32 closely adjacent the forward end portion 22 of the support member 20 . Optionally, the lower end portion 32 of the retaining member 28 can be provided with a lip 34 that extends rearwardly from the lower end portion 32 . In that instance, the forward end portion 22 of the support member 20 should be shaped with a recess portion 36 to closely engage the lip 34 when the retaining member 28 is in its closed position. The lip 34 and recess 36 can provide frictional engagement between one another to provide a method of selectively securing the retaining member 28 in its closed position when the shopping bag handle 10 is in use. Although virtually any shape of lip and recess would function for this purpose, the rounded lip 34 and cove-shaped recess 36 allow retaining member 28 to provide an element of structural support to the shopping bag handle 10 when a heavy load is secured on the support member 20 . Another method of securing the retaining member 28 in a particular open or closed position is provided by a ratchet 38 and pawl 40 , which are shown in greater detail in FIG. 3 . Although the ratchet 38 is depicted as having individual teeth 42 extending radially therefrom, it is contemplated that a plurality of recesses or grooves could also be formed within the ratchet 38 . The pawl 40 is preferably provided with an engagement end 44 and an actuation end 46 . The engagement end 44 is preferably shaped to securely engage the surface features of the ratchet 38 . The actuation end 46 is preferably positioned to extend outwardly from and slightly above the gripping member 12 in a position conveniently adjacent the user's thumb. The pawl 40 is pivotably coupled to the forward end 14 of the gripping member 12 closely adjacent the ratchet 38 , located on the upper end portion 30 of the retaining member 28 . Accordingly, the user is able to disengage the pawl 40 from the ratchet 38 to position the retaining member 28 in an open or closed position, as desired. The user may then engage the pawl member 40 to secure the retaining member 28 in that position. A spring member 48 can optionally be secured coaxially with the pivot point of the retaining member 28 to bias the retaining member 28 toward its open position. Accordingly, when the spring member 28 is used, the user is able to selectively disengage the pawl 40 from the ratchet 38 so that the retaining member 28 extends automatically from a closed position to an open position. In the open position, the handles of the articles or shopping bags can be “threaded” onto the support member 20 . The retaining member 28 can then be moved to its closed position through forward engagement of the upper end portion 30 of the retaining member 28 by the user's thumb until the desired closed position is achieved. It is further contemplated that the user's index finger could be engaged with the side of the retaining member 28 and pulled rearwardly and downwardly in a trigger-pulling fashion. Once the user has reached the delivery destination for the shopping bags or articles being carried, the user simply disengages the pawl 40 from the ratchet 38 to raise the retaining member 28 and slide the shopping bag handle 10 in a rearward direction until the handles of the shopping bags or articles are free of the support member 20 . Where the ratchet and pawl system is not used, the user would engage the retaining member 28 with the user's thumb or finger in the reverse fashion to that described hereinabove. The simple actuation of the retaining assembly using the thumb or fingers of the user's hand that is carrying the shopping bag handle 10 allows the system to be simply used in a one-handed fashion. This permits the user to use a shopping bag handle 10 in each of the user's right and left hands to carry twice the load at the same time. The ability to capture and release shopping bags or articles with a single hand provides a greatly improved convenience and efficiency to the prior art. In the drawings and in the specification, there have been set forth preferred embodiments of the invention; and although specific items are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and proportion of parts, as well as substitution of equivalents, are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims. Thus it can be seen that the invention accomplishes at least all of its stated objectives.	A device for carrying articles having handles is provided with generally elongated gripping and handle supporting members that are positioned in spaced-apart relationship with one another. A retaining assembly is pivotably coupled to the gripping member which can be moved between open and closed positions using the same hand that carries the device. Multiple embodiments are provided for the selective securement of the retaining assembly in its closed and/or open positions. The design of the device lends itself to durable but simple construction.	0
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to a printed loop antenna with introducing a L shape portion to its arms for Ultra Wideband (UWB) signal radiation. [0003] 2. Description of the Related Art [0004] The main difference between UWB communication system and conventional narrowband communication systems is that the UWB system transmits tremendously short pulses without any carrier and occupies bandwidth of more than a few GHz. As a result, the antenna plays an important role in the UWB systems than it in any other system. [0005] Compare to traditional antennas it is more complicated to provide the typical parameters like bandwidth and gain within the limited antenna volume. An antenna design becomes even more critical with respect to the UWB system with high data rate and low power density. Moreover, antennas for the UWB system should have linear phase over the entire frequency, omni-directional patterns, and constant gain. Therefore, UWB antenna should be designed carefully to avoid unnecessary distortions. That's why the UWB antenna design is going to be one of the main challenges for UWB system. [0006] Printed monopole and dipole antennas are extensively used in different wireless applications due to their many advantages, such as low profile, light weight, easy to fabricate and low cost, some of them are references [1]-[2]. [0007] The loop antennas also can be used for wireless communications (references [3]-[5]). [0008] FIG. 11 shows a loop antenna of a prior art. On the top of a substrate 1 , a single metallic layer, which is copper, is printed. However, a conventional wire loop antenna shows less than 10% bandwidth for a 2:1 VSWR. Therefore, conventional loop antenna went under different modifications to increase the bandwidth. A broadband loop antenna has been introduced by reference [3], which have a small gap in the wire loop. This small gap increased the impedance bandwidth to more than 24%. [0009] In this invention we present a loop antenna whose left and upper arms together introduce an L-shape. However, the L-shape antenna itself is a class of broadband planar antenna, which allows the broad impedance bandwidth and less cross-polarization radiation (references [6], [7]). REFERENCES [0000] [1] K. L. Wong, G. Y. Lee, T. W. Chiou, “A low-profile planar monopole antenna for multiband operation of mobile handsets,” IEEE Transactions on Antennas and Propagation, vol. 51, pp. 121-125, January 2003. [2] J. Perruisseau-Carrier, T. W. Hee, P. S. Hall, “Dual-polarized broadband dipole,” IEEE Antennas and Wireless Propagation Letters., Vol. 2, pp. 310-312, 2003. [3] R. L. Li, E. M. Tentzeris, J. Laskar, V. F. Fusco, and R. Cahill, “Broadband Loop Antenna for DCS-1800/IMT-2000 Mobile Phone Handsets,” IEEE Microwave and Wireless Components Letters, vol. 12, pp. 305-707, August 2002. [4] K. D. Katsibas, C. A. Balanis, P. A. Tirkas, and C. R. Birtcher, “Folded Loop Antenna for Mobile Hand-Held Units,” IEEE Transaction on Antennas and Propagation, vol. 46, pp. 260-266, February 1998. [5] R. L. Li, V. F. Fusco, “Circularly Polarized Twisted Loop Antenna,” IEEE Transaction on Antennas and Propagation, vol. 50, pp. 1377-1381, October 2002. [6] Z. N. Chen and M. Y. W. Chia, “Broadband planar inverted-L antennas,” Microwaves, Antennas and Propagation, IEE Proceedings, vol. 148, pp. 339-342, October 2001. [7] Z. N. Chen, M. Y. W. Chia, “Suspended plate antenna with a pair of L-shaped strips,” IEEE APS Symposium, vol. 3, pp. 64-67, June 2002. [8] S. Yamamoto, T. Azakami, and K. Itakura, “Coupled nonuniform transmission line and its applications,” IEEE Transactions on Microwave Theory and Techniques, vol. 15, pp. 220-231, April 1967. [9]. P. Rustogi, “Linearly Tapered Transmission Line and Its Application in Microwaves,” IEEE Transactions on Microwave Theory and Techniques, vol. 17, pp. 166-168, March 1969. [10] N. M. Martin and D. W. Griffin, “A tapered transmission line model for the feed-probe of a microstrip patch antenna,” IEEE APS Symposium, vol. 21, pp. 154-157, May 1983. [11] I. Smith, “Principles of the design of lossless tapered transmission line transformers,” 7 th Pulsed Power Conference, pp. 103-107, June 1989. [12] Y. Wang, “New method for tapered transmission line design,” Electronics Letters, vol. 27, pp. 2396-2398, December 1991. [13] K. Murakami and J. Ishii, “Time-domain analysis for reflection characteristics of tapered and stepped nonuniform transmission lines,” Proceedings of IEEE International Symposium on Circuits and Systems, vol. 3, pp. 518-521, June 1998. SUMMARY OF THE INVENTION 1. Object of the Invention [0023] There are antennas with good impulsive behavior at the cost of poor matching and large reflections. Also there are antennas with resistive loading, which give lower radiation efficiency, but a good matching and high impedance bandwidth. [0024] The large size parabolic antennas with good performance can be used for UWB system, however, make them less suitable for most commercial (with respect to price) and handheld or portable (with respect to size) applications. [0025] The antenna design for Ultra Wideband (UWB) signal radiation is one of the main challenges of the UWB system, especially when low-cost, geometrically small and radio efficient structures are required for typical applications. [0026] In this invention, we propose a novel Loop antenna with very compact size that could be use as an on-chip or stand-alone antenna for UWB system. 2. Means for Achieving the Object [0027] This invention presents a novel printed loop antenna with introducing a L shape portion to its arms. The antenna offers excellent performance for lower-band frequency of UWB system, ranging from 3.1 (GHz) to 5.1 (GHz). The antenna exhibits a −10 (dB) return loss over the entire bandwidth. [0028] The antenna is designed on FR4 substrate and fed with 50 ohms coupled tapered transmission line. It is found that the lower frequency band depends on the L portion of the loop antenna, however the upper frequency limit was decided by the taper transmission line. The proposed antenna is very easy to design and inexpensive. 3. Advantages of the Invention [0029] The wideband L-loop antenna is presented in this invention. It has excellent performance for lower band of UWB system and has the attractive features of small size, inexpensive, and easy to design. A VSWR≦1.6 was shown to be achievable over the entire bandwidth, 3.1-5.1 (GHz). The return loss of −10 dB is achieved over the frequency band. The gain in the whole range of frequency band is more than 1 dBi. Two analysis techniques, Moment Method and Finite Element Method, are applied to design this novel antenna, which could be concluded that, the results are trustable. A good impedance matching has been achieved in the simplest way. BRIEF DESCRIPTION OF THE DRAWINGS [0030] FIG. 1 shows a plane view and cross-sectional views of the L-loop antenna of an embodiment of the present invention. [0031] FIG. 2 shows an example of the L-loop antenna of the present invention. [0032] FIG. 3 shows an example of taper transmission line applying to the L-loop antenna of the present invention. [0033] FIG. 4 shows frequency characteristic of VSWR of the L-loop antenna of the present invention. [0034] FIG. 5 shows frequency characteristic of return loss of the L-loop dipole antenna of the present invention. [0035] FIG. 6 shows frequency characteristic of gain of the L-loop antenna of the present invention. [0036] FIG. 7 shows current distribution of the L-loop antenna of the present invention. [0037] FIG. 8 shows radiation pattern at 3.1 GHz of the L-loop antenna of the present invention. [0038] FIG. 9 shows radiation pattern at 4.1 GHz of the L-loop antenna of the present invention. [0039] FIG. 10 shows radiation pattern at 5.1 GHz of the L-loop antenna of the present invention. [0040] FIG. 11 shows a loop antenna of the a prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0041] FIG. 1 and FIG. 2 show the novel low profile planar L-loop antenna. FIG. 1 shows an embodiment of the present invention. FIG. 1A is a plane view of the L-loop antenna, FIG. 1B is a cross-sectional view at X-X′, and FIG. 1C is a cross-sectional view at Y-Y′. FIG. 2 shows an example of the L-loop antenna as shown in FIG. 1 . In FIG. 1 a substrate 1 is made of insulation material such as FR-4, Teflon (Registered Trademark), or silicon, and on the substrate 1 , a L-loop antenna is made of metal such as copper, silver, platinum, gold or aluminuim. [0042] In FIG. 1 , a novel printed loop antenna with introducing a L shape portion- to its arms is shown. The antenna is formed into a square or rectangular loop configuration having four arms. A first arm is cut off at the center and the both cut ends are connected respectively to a couple of tapered transmission lines 4 , 5 . Second and third side arms are connected respectively with the outer ends of the first arm. Each of the other ends of the second and third arms are connected to both ends of a fourth arm opposing to the first arm thereby to form a square or rectangular loop. [0043] The L shape portion is formed by widening the width of one of the side arms and the fourth arm in comparison with the other side arm and the first arm which is connected with the coupled tapered transmission line 4 , 5 . However, it is not necessarily required that the width over the whole length of the one side arm and the fourth arm is widened. The width may be widened over the partial length of each of the one side arm and the fourth arm. [0044] To have a linearly polarized radiation the total length of outer limits of the square (or rectangular) loop antenna should be in substantially one wavelength. Designing an antenna for 3.1 GHz will give the wavelength of λ 0 =96.77 mm. The proposed antenna is composed of a single metallic layer, which is copper, with thickness of h m , and printed on the top of a substrate 1 of thickness h s and relative permittivity ε r . A coupled tapered transmission line 4 , 5 is printed on the top of same substrate 1 . [0045] The metallic layer has thickness of h m =0.018 mm. The patch is on a substrate with ε r =4.4, loss tangent of tan θ=0.02, and thickness of h s =1 mm. The size of the proposed antenna is 24×25×1 mm, which is quite appropriate for wireless system. The square loop has 98 mm length, which is fairly close to one wavelength of antenna design. The reference plane is at the center of antenna. [0046] The transmission lines 4 and 5 are connected to an external circuit device (not shown). The transmission lines shown in FIG. 1 is a linear taper type of which outer side configuration is linear. The tapered transmission lines are gradually widened from its connected portion to the antenna elements, and is formed one body with the antenna elements on the substrate. [0047] The tapered transmission lines have shown good impedance matching over a wide frequency range (references [8]-[13]). The antenna is fed from a 50 Ohms coaxial cable through a coupled tapered transmission line. The geometry of the taper is chosen to minimize the reflection and optimize impedance matching and bandwidth. [0048] The proposed antenna can be made from a plate composed of a substrate of FR 4 and a copper plate stick on the substrate. The antenna patterns composed of the antenna elements and the impedance matching portions are made by photo-etching the copper plate, for example. A layer of photo-resist film is formed on the copper plate by painting photo-resist. Next the painted photo-resist layer is exposed through a photo-mask, which has the pattern of the antenna elements and the impedance matching portion. The photo-resist film is soaked in solution to dissolve the not lighted portion. The lighted portion of the photo-resist layer is left on the copper plate. The left portion of the exposed photo-resist layer on the copper is used as an etching musk. Further the whole is soaked in etching liquid and etches the copper plate with the etching musk of photo-resist. Thus the L-loop antenna to which the taper transmission line 4 and 5 are united is formed on the substrate. [0049] FIG. 2 shows an example of detail size of the L-loop antenna. [0050] FIG. 3A-3C shows some examples of taper transmission lines of the present invention. FIG. 3A is a taper line type transmission line. FIG. 3B is a curved type transmission line of which outer side configuration is curved. FIG. 3C shows a step type transmission line. [0051] FIG. 4-FIG . 10 show various characteristics of the embodiment. The characteristics are obtained from the L-loop antenna having transmission lines of the size of FIG. 2 and FIG. 3A . [0052] The designed antenna can operate in the frequency range of 3.1-5.1 GHz. The proposed design is described in detail, and simulation results of the antenna are presented. The simulation results have been obtained from two different softwares, Ansoft Designer® 1.1 and Ansoft High Frequency Structure Simulator, HFSS® 9.1, to make sure that the obtained results are trustable. [0053] FIG. 4 shows frequency characteristic of VSWR (Voltage Standing Wave Ratio) of the antenna. FIG. 4 is showing that, the designed antenna has VSWR≧1.6 from frequency of 3.1 to 5.1 GHz. [0054] FIG. 5 shows the return loss of invented antenna. The return loss is less than −10 dB in the entire frequency range. It is clearly seen that a wide operating bandwidth is obtained. [0055] FIG. 6 shows the frequency characteristic of antenna gain of the antenna of the present invention. As shown in the Figure, the designed antenna is achieved more than 1 dBi gain in the entire frequency. [0056] FIG. 7 shows current distribution of the L-loop antenna of the present invention. In the figure, the lighter the portion is, the stronger the current. FIG. 8-10 plots the radiation pattern at 3.1, 4.1, and 5.1 GHz. The x-y coordinates are defined as shown in FIG. 1 that the origin is set at the center of the antenna plane and x-axis and y-axis are defined. The z axis is defined as perpendicular to the antenna plain and passing through the origin on the antenna plane. [0057] In FIG. 8-FIG . 10 , the pattern of real line is the radiation pattern of φ=0 degree, and the dotted line is φ=90 degree. The characteristics shows the antenna of the present invention has good radiation patterns. It can be seen that, the radiation pattern almost remain same for all the frequency, which is very important for the wireless system with high data rate.	The wideband L-loop antenna is presented in this invention. It has excellent performance for lower band of UWB system and has the attractive features of small size, inexpensive, and easy to design. The antenna composed of a single metallic layer is printed on the top of a substrate and a coupled tapered transmission line is printed on the top of the same substrate. A L shape portion is formed by widening partially or wholly the width of a part of antenna elements in comparison with the other part.	7
BACKGROUND OF THE INVENTION 1 Field of the Invention. The field of the invention is protective covers for swimming pools. 2. Description of Related Art. Swimming pool covers are utilized by owners of swimming pools for many reasons such as safety, i.e., to provide a cover for the pool during periods of non-use which will prevent a child who has fallen into the pool from going under water or drowning. In most of these cases, the pool cover is usually supported on the sides of the pool. In addition, there are health reasons for such a protective cover, such as preventing dust or other materials from falling into the water surface and then either being dissolved in the water or sinking to the bottom. Further, the pool covers may be used to keep a pool warmer by effecting retention of heat in the water such as that a wind passing over the water surface will not remove the heat as fast as it would on an unprotected pool. In this regard, pool covers may also be made of dark materials which absorb heat from the sun and transfer that heat into the water and thus provide a means for heating the pool. Lastly, a pool cover may be utilized to prevent the rapid dissipation of chlorine from the water which the operator has added to keep the pool sanitized. Numerous pool type blankets have been patented by various and different persons, such as the blanket shown in U.S. Pat. No. 4,109,325 to Shuff wherein a buoyant cover floats on the top of the pool with ballast weights added at the edges of the cover to keep it in position upon the pool. In addition, other variations have been disclosed such as the swimming pool cover shown in U.S. Pat. No. 4,094,021 to Rapp wherein a blanket is held in place by tie anchoring members secured to the pool side walls. Pusey, in U.S. Pat. No. 3,600,721 shows a variation of Shuff's device wherein the plenum between the pool blanket and the water surface may be inflated to cause the blanket to rise substantially above the water surface, sufficient for a person to enter the plenum. Lof details a swimming pool cover in U.S. Pat. No. 4,251,889 having a rigid framework attached to a plastic cover where the cover floats on the water and the framework is tied to the pool decking at spaced apart positions. However, none of the prior art illustrates a pool blanket which provides all of the safety, health, and heat retention features and in addition, is constructed such as to be easily and neatly removed and stacked or set off from the pool and then replaced with minimum effort. Accordingly, it is apparent that there is a need for a flotation pool blanket which provides all of the above features and in addition, provides easy methods of removal of the blanket from the swimming pool and easy methods of replacing the blanket when desired. SUMMARY OF THE INVENTION This invention relates to apparatus for a flotation pool blanket adapted to cover a swimming pool at the water level as a barrier between the water and the surrounding environment to provide health, safety, and heat retention features and yet is easily removable and replaceable on and off the pool water surface. Briefly, the subject inventive flotation pool blanket comprises a plastic flotatable blanket which extends over the complete surface of the water in the pool and which has parallel spaced ribs underlying the blanket and attached to the blanket. The ribs extend over the sides of the pool to provide means to hold the blanket in place against lateral shifting due to wind or the like and additionally provide handles by which the blanket may be lifted up. By traversing the length of the pool and gathering in turn each of the ribs, the entire blanket is lifted and carried off the water and away from the pool for storage until the blanket is replaced upon the pool. The invention is characterized by having reinforced end ribs at opposite ends of the pool with a plurality of central ribs equally spaced between the ends. All ribs have an elongated horizontal member with an upright member at each end adapted to be proximate each side of the pool, the upright member then having a right angle ear member which laps over the pool decking to hold the rib in place, and thus also hold the blanket in place. Each rib underlies the blanket and is attached to the blanket by a plurality of spaced apart rivets which penetrate the blanket to the ribs. The ribs are constructed of PVC pipe and PVC pipe couplings or fittings. It is an object of the subject invention to provide a flotation pool blanket which provides health, safety, and heat retention features while at the same time providing means for easy removal and replacement. It is further an object of the subject invention to provide a flotation pool blanket that may be lifted from the pool surface by handles which rise up above the pool surface to engage the top of the pool decking. It is still further an object of the subject invention to provide a flotation pool blanket that may be gathered for removal such that persons may start at one end of the pool and while proceeding the length of the pool, gather up each part of the blanket, lifting it above the water until the total blanket has been lifted out, and then stow the blanket away. Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus comprising the construction, combination of elements, and arrangement of parts which are exemplified in the following detailed disclosure and the scope of the Application which will be indicated in the claims. BRIEF DESCRIPTION OF THE DRAWINGS For further understanding of the nature and object of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein: FIG. 1 is a sectioned perspective view of the subject invention in place on a swimming pool. FIG. 2 is a top view of a swimming pool with the subject invention in place; FIG. 3 is a side view of an end rib; FIG. 4 is a side view of a central rib; FIG. 5 is an end side view of a central rib with blanket at the edge of the pool; FIG. 6 is an alternate embodiment of a central rib at the edge of the swimming pool where the swimming pool has an overhanging coping; FIG. 7 is an alternate embodiment of a portion of a central rib utilizing wheels on the ear of the rib; and FIG. 8 is an alternate embodiment of a top view of an oval shaped pool with the invention in place. In various views, like index numbers refer to like elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a perspective sectioned view of the inventive flotation pool blanket 10 installed on a swimming pool is shown. Flotation pool blanket 10 is so positioned to float upon the surface of the water 26 in the swimming pool while supported against lateral movement by the central ribs 12 positionally spaced between the ends of the blanket 14 and the end rib 16. End rib 16 comprises similar construction as central ribs 12 except that it has additional lengthwise reinforcement. The blanket 14 which is preferably constructed of sheet plastic, is attached to the central ribs 12 and the end rib 16 at various spaced points, the preferable method of attachment being rivets with an oversized head which will be shown in later drawings. The central ribs 12 and end ribs 16 are supported by means of attached ears situated at opposite ends of each rib, the ears adapted to lay upon the deck 18 of the swimming pool. The upright members of the central ribs 12 and end ribs 16 which rise perpendicularly from the horizontal members of the rib have such a length as to reach down to the surface of the water 26 in order to lay the blanket upon the surface of the water, with the ribs horizontal member 22 (shown in dotted form in FIG. 1) lying just underneath blanket 14 and therefore just immediately below the surface of the water 26. The horizontal reinforcing member 24 of end rib 16 is shown above blanket 14 and attaches at the point where the ear of the end rib 16 also attaches. Referring now to FIG. 2, a top view of the inventive flotation pool blanket 10 is shown in place in a rectangular shaped pool 30. As seen in FIG. 2, the various central ribs 12 are generally equally spaced throughout the length of pool 30 and end ribs 16 are situated at opposite ends. Blanket 14 is shown covering the ribs and also covering the water of the pool. It is anticipated that the blanket should join the sides of the pool with minimal space between the end of the blanket and the side of the pool as it is desired that the pool be completely covered. As can be seen in FIG. 2, the ribs extend from one side to the other and overlap the pool deck 18 on both sides. It is realized of course that while the choice has been to place the ribs across the width of the pool rather than the length of the pool, it is always possible that the ribs can extend the longer length of the pool rather than its shorter width. FIG. 3 is a side view of the complete end rib 16 showing in this view the rib lower horizontal member 22, the upper reinforcing member 24, and the upright strengthening members 20 at each end and situated at spaced positions between the two ends. At each end and in line with the upper reinforcing member 24 is rib ear 28, rib ear 28 adapted to rest upon the deck of the pool. Rib ear 28 is connected by means of an appropriate "T" pipe fitting or coupling to upright member 20 and upper reinforcing member 24. All connections between upper reinforcing member 24 and upright member 20 as well as the connection between lower reinforcing member 22 and upright member 20 are effected with appropriate "T" or right angle pipe fittings. FIG. 4 shows a side view of central rib 12, the usual type adapted to be positioned in the central portion between the ends of the pool. Rib 12 shown in FIG. 4 comprises the rib horizontal member 22, upright member 20, and rib ear 28, all identical to their respective similar element in the end rib 16. All rib members are connected by appropriate right angle pipe fittings. There is interchangeability between the end rib 16 and centrally located ribs 12 so long as the length to be spanned is not too great. Since the ribs will be picked up and carried along by two members walking on opposite sides of the pool, weight of the blanket and weight of the PVC pipe utilized will be the factors determining whether or not a strengthening upper reinforcing member is necessary. Obviously for extended lengths, the upper reinforcing member 24 will be necessary, and in those cases it is advised that all ribs, including central ribs, be of the same construction as the end rib 16. Similarly, for short widths to be spanned, all ribs, including the end ribs, can be of the simpler construction shown in the central rib of FIG. 4. Continuing, FIG. 5 is a side view of the end of a typical centrally located rib 12 with a partial cutaway view of pool deck 18. In this Figure is illustrated the relationship of blanket 14 to the horizontal member 22 and the water 26. Blanket 14 floats upon the top level of water 26 with the rib horizontal member 22 just below the surface of the water. Blanket 14 is attached to the rib horizontal member 22 by means of a large headed rivets 32 which, in the preferred embodiment, are constructed of aluminum or non-rusting metal such as stainless steel, copper, or the like. Shown as a solid plug in rib horizontal member 22 is weight 34 which may comprise a heavy metal such as lead or the like, or other heavy material which are employed to add weight to the combined blanket and ribs in order to make the combination more stable in the event of wind or the like. Weights 34 may be spaced at various intervals in the hollow center of the PVC pipe making up the rib or may be substantially filling in the center for the total length. The weights may also comprise round pellets 35 which may be fixed in place or freely moving within the rib horizontal member. An opening in blanket 14 has been cut in order to encircle upright member 20 so that the blanket extends to the wall of the pool, or if desired, the blanket may terminate in the vicinity of upright 20 and thereby be slightly spaced away from the pool wall. Connected to upright 20 by means of right angle pipe fitting 36 is rib ear 28 which in turn is terminated with end cap 38. Another right angle pipe fitting 36 is shown joining upright member 20 with rib horizontal member 22. Referring now to FIG. 6, a variation of central rib 12 is shown to accommodate a pool constructed with an overhanging edge or coping. By the manner of construction shown in FIG. 6, the blanket may still extend to the edge of the wall, however, the upright member 20 is recessed back from the wall sufficiently so as not to interfere with the edge of the deck 19 having the extended coping. Here again, as in FIG. 5, blanket 14 is shown encircling upright member 20 and a portion of "T" pipe fitting 40, and then proceeds over to the wall of the pool. Extending beyond "T" pipe fitting 40 and in line with the rib horizontal member 22 is the rib horizontal member extension 42 which extends to the wall or nearly to the wall of the pool. The blanket 14 is riveted in place to the rib horizontal member 22 and rib horizontal extension member 42 by means of rivets 32, which are the same type of rivets utilized and shown in FIG. 5. Rib horizontal member extension 42 is similarly capped with end cap 38 as is the ear 28 which also is connected to right angle pipe fitting 36, as is also upright member 20. Here, as in the illustration in FIG. 5, blanket 14 lays on top of water 26 with the rib horizontal member 22 immediately below the surface of the water. While rivets have been shown as the means of attachment of the plastic sheet to the ribs, it is possible that different types of attachment may be made, such as using an appropriate water-proof adhesive. Also shown in dotted form in FIG. 6 is the construction utilized to produce an end rib for the alternate embodiment, and more particularly, the addition of upper reinforcing member 24. A "T" pipe fitting, such as that shown as numeral 40 in FIG. 6, is utilized rather than the right angle pipe fitting 36 shown in order to receive the horizontal upper reinforcing member 24. It is realized of course that the same construction for a standard end rib 16 is utilized for the preferred standard central rib 12 shown in FIG. 5, i.e., the upper right 20 angle pipe fitting 36 shown in FIG. 5 would be replaced by a "T" pipe fitting in order to receive the upper reinforcing member 24. FIG. 7 shows an alternate embodiment of the invention in a side view where a wheel 44 is shown rotationally attached to rib ear 28. It is suggested that a straight fitting, such as shown by numeral 43, be added to rib ear 28 in order to limit sidewise movement of wheel 44. Secondly, in this alternate embodiment, the relative positions of blanket 14 and rib 22 have been reversed inasmuch as here the rib 22 lies atop blanket 14, blanket 14 still lying on the surface of water 26. Again, as before, rivets 32 attach blanket 14 to rib 22. Lastly, FIG. 8 shows a top view of an oval shaped pool 50 with the inventive flotation pool blanket 10 in place. Here all of the ribs 52 are of different lengths, however, their construction is the same as has been detailed in FIGS. 1 through 6. Again, the choice of type of ribs to utilize in the oval pool shown in FIG. 8, i.e., whether using a central type rib or an end type rib with the added upper strengthening member, is a matter of choice depending upon the length to be spanned, the size and strength of the parts of the ribs, the weight of the blanket, and whether additional weights has been added. In the preferred construction, the centrally located ribs and end ribs were preferably constructed from PVC pipe, schedule 40, and the various couplings or fittings, i.e., "T" fittings, right angle fittings, straight fittings, and end caps, also from the PVC molded plastic adapted to be used with the PVC pipe. The wheel shown in FIG. 7 may also be made of a rigid plastic for convenience. The blanket 14 which has been utilized in the preferred embodiment was the type of blanket which entrains air bubbles and is manufactured by the Sealed Air Corporation. It is realized that any type of blanket material may be utilized since if the blanket is not sufficiently light enough to float, the ribs themselves will hold the blanket on or above the water. In utilizing the invention, and when the flotation pool blanket is lying on the surface of the water, the preferred method of removal is for two persons to start at one end on opposite sides of the pool, to reach down and simultaneously pick up the end rib. Then, walking together towards the other end of the pool, proceed to the next central rib, reach down, and pick it up and carry it above the water to the next central rib. The blanket begins to adopt a serpentine type appearance when viewed at the sides. This process is repeated until both parties have reached the other end and then the sole remaining rib is the end rib which is also picked up in the same manner. Since each party is now carrying the total flotation blanket by each of the ears, the blanket may then be carried off to a remote place and then set upon the ground for storage until the pool is to be re-covered. In applying the inventive flotation pool blanket to the pool, a number of different methods may be utilized. Firstly, opposite ends of all of the ribs are picked up by two persons, one on each side, and then the flotation pool blanket carried to one end of the pool and one end rib set down in the pool. Thereafter, each party proceeds along the edge of the pool, dropping off one of each sequential rib as the blanket, which was folded up in a serpentine type fashion, is let down, until the whole pool is covered. A second method which may be utilized is to bring the flotation pool blanket to the end of the pool and then place one end rib and all the central ribs into the pool, retaining only the other end rib which is to be placed at the opposite end of the pool. Then the parties walk along the sides of the pool causing the flotation pool blanket to unfold and slide across the water, pulling the ribs sequentially with it. The flotation pool blanket will then be completely unfolded on the surface of the water as the two parties reach the opposite end of the pool at which time, the last end rib may be dropped into place. After the blanket is in place, it may be necessary to ensure that the flotation pool blanket does fully cover the water in the pool and to achieve that, the persons the other side of the pool, and perform the same operation after stationing themselves at each of the pool's ends. It is not anticipated that the same procedure will be necessary to ensure that the pool blanket comes up fully to the sides of the width of the pool since the ribs' position ensures that the blanket is up against the sides of the width. In the alternate embodiment, it is apparent that the ribs may overlay the blanket and be on top, although it is equally apparent that such an embodiment would place added stress upon the blanket, and may result in tearing of the blanket. While a preferred embodiment of the invention has been shown and described, together with alternate embodiments, it will be understood that there is no intent to limit the invention by such disclosure, but rather it is intended to cover all modifications of the apparatus and alternate constructions falling within the spirit and the scope of the invention as defined in the appended claims.	A flotation pool blanket for covering a swimming pool adapted to be gathered when removed, said flotation pool blanket defining a blanket covering the water of the pool having at spaced intervals, parallel ribs underlying the blanket, the ribs at each end rising up to form ears which overlap and engage the top of the pool decking surrounding and defining the pool. Further, the ears provide means by which the flotation pool blanket may be gathered up for removal by starting at one end, picking up the rib, proceeding to the next rib and repeating the step until all the ribs have been picked up at which time the blanket and the ribs carried to a position away from the pool. Emplacement of the invention pool blanket is just the opposite of removal, the operators dropping one end of the flotation pool blanket in the pool and then proceeding to let out a rib as they traverse the length of the pool.	4
CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of application Ser. No. 08/367,516, filed Dec. 30, 1994 now abandoned. This application is related to application Ser. No. 08/367,027, filed on Dec. 30, 1994, which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION This invention relates to current switching MOSFETs having a gate formed in a trench and in particular to a trench MOSFET (metal-oxide-silicon field-effect transistor) having a lower resistance when the device is turned on. BACKGROUND OF THE INVENTION Power MOSFETs are widely used in numerous applications, including automotive electronics, disk drives and power supplies. Generally, these devices function as switches, and they are used to connect a power supply to a load. It is important that the resistance of the device be as low as possible when the switch is closed. Otherwise, power is wasted and excessive heat may be generated. A common type of power MOSFET currently in use is a planar, double-diffused (DMOS) device, illustrated in the cross-sectional view of FIG. 1. An electron current flows laterally from source regions 12 through channel regions formed within P-body regions 14 into an N-epitaxial layer 16. Current flow in the channel regions is controlled by a gate 18. After the current leaves the channel regions, it flows downward through N-epitaxial layer 16 into an substrate 20, which forms the drain of the device. A parasitic junction field effect transistor (JFET) is formed by the existence of P-body regions 14 on either side of an intervening region of N-epitaxial layer 16. A depletion zone 22 adjacent the junction between each of P-body regions 14 and N-epitaxial layer 16 tends to squeeze the current and thereby increase the resistance in this area. As the current proceeds downward through N-epitaxial layer 16 it spreads out and the resistance decreases. In an alternative form of vertical current flow device, the gate is formed in a "trench". Such a device is illustrated in FIG. 2A, which is a cross-sectional view of a single cell of a MOSFET 100, and in FIG. 2B, which is a plan view of the cell. Gates 102 and 104 are formed in trenches and surrounded by gate oxide layers 106 and 108, respectively. The trench gate is often formed in a grid pattern including an array of polygonal shapes (one section of which is shown in FIG. 2B), the grid representing a single interconnected gate (gates 102 and 104 being the same), but a trench gate may also be formed as a series of distinct parallel stripes. MOSFET 100 is a double-diffused device which is formed in an N-epitaxial layer 110. A N+ source region 112 is formed at the surface of epitaxial layer 110, as is a P+ contact region 114. A P-body region 116 is located below N+ source region 112 and P+ contact region 114. A metal source contact 118 makes contact with the source region 112 and shorts the source region 112 to the P+ contact region 114 and P body region 116. The N-epitaxial layer 110 is formed on a substrate 120, and a drain contact (not shown) is located at the bottom of the substrate 120. The contact for the gates 102 and 104 is likewise not shown, but it is generally made by extending the conductive gate material outside of the trench and forming a metal contact at a location remote from the individual cells. The gate is typically made of phosphorus or boron doped polysilicon. A region 111 of N-epitaxial layer 110 between the substrate 120 and the P body 116 is generally more lightly doped with N-type impurities than substrate 120. This increases the ability of MOSFET 100 to withstand high voltages. Region 111 is sometimes referred to as a "lightly doped" or "drift" region ("drift" referring to the movement of carriers in an electric field). Drift region 111 and substrate 120 constitute the drain of MOSFET 100. MOSFET 100 is an N-channel MOSFET. When a positive voltage is applied to gate 102, a channel region within P-body region 116 adjacent the gate oxide 106 becomes inverted and, provided there is a voltage difference between the source region 112 and the substrate 120, an electron current will flow from the source region through the channel region into drift region 111. In drift region 111, some of the electron current spreads diagonally at an angle until it hits the substrate 120, and then it flows vertically to the drain. Other portions of the current flow straight down through drift region 111, and some of the current flows underneath the gate 102 and then downward through drift region 111. The gate 102 is doped with a conductive material. Since MOSFET 100 is an N-channel MOSFET, gate 102 could be polysilicon doped with phosphorus. Gate 102 is insulated from the remainder of MOSFET 100 by the gate oxide 106. The thickness of gate oxide 106 is chosen to set the threshold voltage of MOSFET 100 and may also influence the breakdown voltage of MOSFET 100. The breakdown voltage of a power MOSFET such as MOSFET 100 would typically be no greater than 200 volts and more likely 60 volts or less. One feature that makes the trench configuration attractive is that, as described above, the current flows vertically through the channel of the MOSFET. This permits a higher packing density than MOSFETs such as the planar DMOS device shown in FIG. 1 in which the current flows horizontally through the channel and then vertically through the drain. Greater cell density generally means more MOSFETs per unit area of the substrate and, since the MOSFETs are connected in parallel, the on-resistance of the device is reduced. In MOSFET 100 shown in FIG. 2A, the P+ contact region 114 is quite shallow and does not extend to the lower junction of the P-body region 116. This helps ensure that P-type dopant does not get into the channel region, where it would tend to increase the threshold voltage of the device and cause the turn-on characteristics of the device to vary from one run to another depending on the alignment of the P+ contact region 114. However, with a shallow P+ region 114, the device can withstand only relatively low voltages (e.g., 10 volts) when it is turned off. This is because the depletion spreading around the junction between P-body region 116 and drift region 111 does not adequately protect the corners of the trench (e.g., corner 122 shown in FIG. 2A). As a result, avalanche breakdown may occur in the vicinity of the trench, leading to a high generation rate of carriers which can charge or degrade the gate oxide 106 or even, in an extreme case, cause a rupture in the gate oxide 106. Thus the MOSFET 100 shown in FIG. 2B is at best a low voltage device. FIG. 2C illustrates a modification of MOSFET 100 in which the P+ body contact region 114 is extended downward slightly beyond the lower junction of P-body region 116. The higher concentration of P ions in this region increases the size of the depletion area, and this provides some additional shielding around the corner 122 of the trench. However, if this device is pushed into breakdown, the generation of carriers will still most likely occur near gate oxide layer 106, and this could lead to the impairment of the gate oxide as described above. The breakdown situation was significantly improved in the arrangement shown in FIGS. 3A-3C, which was described in U.S. Pat. No. 5,072,266 to Bulucea et al. In MOSFET 300, the P+ region 114 is extended downward below the bottom of the trench to form a deep, heavily-doped P region at the center of the cell. While this provides additional shielding at corner 122, the primary advantage is that carrier generation occurs primarily at the bottom tip 302 of the P+ region 114. This occurs because the electric field is strengthened beneath the tip 302, thereby causing carriers to be generated at that point or along the curvature of the junction rather than adjacent the gate oxide 106. This reduces the stress on gate oxide 106 and improves the reliability of MOSFET 300 under high voltage conditions, even though it may reduce the actual junction breakdown of the device. FIG. 3B illustrates a perspective cross-sectional view of the left half of the cell shown in FIG. 3A, as well as portions of the adjoining cells. FIG. 3C shows a comparable P-channel device. FIG. 3D illustrates how a gate metal 121 may be used to form a connection with gates 102 and 104. The deep central P+ region 114 in MOSFET 300, while greatly reducing the adverse consequences of breakdown, also has some unfavorable effects. First, an upward limit on cell density is created, because with increasing cell density boron ions-may be introduced into the channel region. As described above, this tends to increase the threshold voltage of the MOSFET. Second, the presence of a deep P+ region 114 tends to pinch the electron current as it leaves the channel and enters the drift region 111. In an embodiment which does not include a deep P+ region (as shown in, for example, FIG. 2A), the electron current spreads out when it reaches drift region 111. This current spreading reduces the average current per unit area in the N epitaxial layer 110 and therefore reduces the on-resistance of the MOSFET. The presence of a deep central P+ region limits this current spreading and increases the on-resistance. What is needed, therefore, is a MOSFET which combines the breakdown advantages of a deep central P+ region with a low on-resistance and a good current distribution in the epitaxial layer. SUMMARY OF THE INVENTION The trench MOSFET of this invention includes a gate formed in a trench, a source region of a first conductivity type, a body region of a second conductivity type located under the source region, a drain region of first conductivity type located under the body region, and a "lightly doped" or "drift" region within the drain region, the dopant concentration of the drift region being lower than the dopant concentration of the drain region generally. The drain may include a substrate or, in "quasi-vertical" embodiments, the drain may include a buried layer of first conductivity which is connected to the top surface of the semiconductor material via, for example, a "sinker" region. The drift region may be formed in an epitaxial layer or a substrate. When the MOSFET is turned on, an electron current flows vertically through a channel within the body region adjacent the trench. In accordance with the invention, the drift region includes regions of differing resistivity. A region of relatively high resistivity is formed in the drift region generally below and adjacent to the trench. The region of high resistivity is doped with ions of the first conductivity type at a concentration which is lower than the concentration of ions of the first conductivity type in other parts of the drift region. There are numerous variants of this arrangement. For example, the region of high resistivity may have a substantially uniform dopant concentration (and resistivity); or the dopant concentration may vary (e.g., linearly or according to some other function) in the region of high resistivity. The region of high resistivity should encompass the point on the trench boundary (e.g., a corner) where the electric field reaches a maximum when the MOSFET is subjected to a source-to-drain voltage while the MOSFET is in an off condition. In a preferred embodiment, the drift region also includes a "delta" layer, which has a lower resistivity than the region of high resistivity, since the delta layer is doped with ions of the first conductivity type at a concentration higher than the concentration of such ions in the region of high resistivity. The delta layer is typically formed at a central location of the MOSFET cell, away from the trench, although in some embodiments the delta region may extend to or under the trench. The delta layer has a resistivity that is higher than the resistivity of regions of the drain surrounding the delta layer. The region of high resistivity adjacent the trench limits the strength of the electric field along the boundary of the trench, particularly at sharp corners, and thereby helps to prevent voltage breakdown near gate oxide layer. The "delta" layer helps insure that any voltage breakdown will occur near the center of the MOSFET cell rather than at the surface of the gate oxide. Moreover, the delta layer improves the distribution of the current and reduces the on-resistance of the MOSFET. This technique reduces the electric field at the trench without limiting increases in cell density in the manner of the deep central region of second conductivity described above. Moreover, the electron current is not crowded in the region of the trench, and hence the on-resistance of the MOSFET is improved as compared with embodiments having a deep central diffusion. Alternatively, particularly where cell density is not a paramount concern, a region of second conductivity type may be formed at the center of the MOSFET cell to help control the electric field strength at the edge of the trench. The central region of second conductivity type may be used alone or in conjunction with a delta layer. As used herein, terms which define physical direction or relationships, such as "below", "higher" or "lateral", are intended to refer to a MOSFET oriented as shown in FIGS. 3A-3C and 4, with the trench at the top surface of the device. It is understood that the MOSFET itself may be oriented in any manner. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a cross-sectional view of a conventional planar double-diffused MOSFET. FIGS. 2A and 2B illustrate cross-sectional and plan views, respectively, of a cell of a typical vertical trench N-channel MOSFET having a relatively shallow central P+ contact region. FIG. 2C illustrates a cross-sectional view of a similar N-channel MOSFET in which the central P+ contact region has been extended below the bottom edge of the P body region. FIG. 3A illustrates a cross-sectional view of a similar N-channel MOSFET in which the central P+ contact region has been extended to a location below the bottom of the trench. FIG. 3B illustrates a perspective cross-sectional view of the N-channel MOSFET shown in FIG. 3A. FIG. 3C illustrates a perspective cross-sectional view of a similar P-channel MOSFET. FIG. 3D illustrates a cross-sectional view showing a gate metal contact formed on the top surface of the device. FIG. 4 illustrates a cross-sectional view of a MOSFET in accordance with this invention. FIG. 5A illustrates a graph showing the concentration of dopant through a cross-section taken through the gate of the MOSFET shown in FIG. 4. FIG. 5B illustrates a graph showing the concentration of dopant at a cross-section taken near the channel of the MOSFET shown in FIG. 4. FIG. 5C illustrates a graph showing the concentration of dopant at a cross-section taken at the center of the cell of the MOSFET shown in FIG. 4. FIGS. 6A-6J illustrate steps in a process of fabricating a MOSFET in accordance with the invention. FIG. 6K illustrates profiles of the dopant concentration in the drift region in various embodiments of the invention. FIGS. 7A and 7B illustrate cross-sectional views of a MOSFET including an delta layer in conjunction with a central P+ region. FIGS. 8A and 8B illustrate cross-sectional views of a MOSFET including a delta layer which extends to the side walls of the trench. FIG. 9A illustrates the distribution of current in a 5 μm cell MOSFET in accordance with this invention. FIG. 9B illustrates the current distribution in a conventional 9 μm cell MOSFET. FIG. 10A illustrates the equipotential lines in the 9 μm cell MOSFET. FIG. 10B illustrates the electric field contours in the 9 μm cell MOSFET. FIG. 11A illustrates the equipotential lines in the 5 μm cell MOSFET in accordance with this invention. FIG. 11B illustrates the electric field contours in the 5 μm cell MOSFET in accordance with this invention. FIG. 12A illustrates the ionization rates in the conventional 9 μm cell MOSFET. FIG. 12B illustrates the ionization rates in the 5 μm cell MOSFET in accordance with this invention. FIG. 13 illustrates a cross-sectional view of an embodiment in the form of a quasi-vertical MOSFET. In the various figures of the drawing, like reference numerals are used to designate similar elements. DESCRIPTION OF THE INVENTION A cross-sectional view of a MOSFET 40 in accordance with the invention is illustrated in FIG. 4. MOSFET 40 includes an N+ source region 41, a P-body region 42 and an N drain region 43. A gate 44 is formed in a trench 48 and is insulated from the active regions of the device by an oxide layer 45. A P+ contact region 46 is formed adjacent source region 41, and regions 41 and 46 are shorted together by a metal contact 46M. N drain region 43 includes four different regions in this embodiment: an substrate 43S; a "drift" region 43D; a region of high resistivity 43HR adjacent a portion of trench 48; and a central "delta" layer 43LR, which has a low resistivity compared to region 43HR. As used herein, the term "delta layer" means a layer beneath the body region in a trenched vertical MOSFET in which the dopant concentration is greater than the dopant concentration in a region immediately below the delta layer. The boundaries of the delta layer are located where the dopant concentration ceases to decrease (i.e., either remains the same or increases) or where the delta layer abuts the body region. (Some of the dopant used to form the delta layer may extend into the body region, although in this event the dopant used to form the body region will compensate for and counterdope the delta layer dopant in the area of the overlap.) The lower boundary of the delta layer may be located at a level which is either above or below the bottom of the trench, and which is either above or below the bottom of a region of opposite conductivity at the center of the cell. The upper boundary of the delta layer may coincide with the lower junction of the body region, or the upper boundary of the delta layer may be below the lower junction of the body region. Drift region 43D and all of the overlying semiconductor layers are formed in an epitaxial layer 47, which is formed on the top surface of substrate 43S. The trench 48 is also formed in epitaxial layer 47. In other embodiments, the drift region may be formed in a substrate. Moreover, while trench 48 is rectangular in cross section, the trench may alternatively be U- or V-shaped or some other shape. FIG. 4 illustrates a cross-sectional view of a half-cell of MOSFET 40. Thus, the left hand edge of the drawing is located approximately at the center of gate 44, and the cross-section designated 5C--5C is at the center of the cell. Gate 44 could be formed in a rectilinear, hexagonal or other type of grid pattern (see FIGS. 3B and 3C), in which case a "cell" would include an area bounded on all sides by a portion of gate 44. Alternatively, gate 44 could be in a series of parallel gate "stripes". The structure of MOSFET 40 will be better understood by reference to FIGS. 5A, 5B and 5C, which show the concentration of N- or P-type dopant at three vertical cross-sections. FIG. 5A shows the dopant concentration at the cross-section designated 5A--5A in FIG. 4, which extends through a central portion of gate 44. The horizontal axis of FIG. 5A is the distance (in μm) below the top surface of epitaxial layer 47, and the vertical axis is the log 10 of the dopant concentration (in cm -3 ). The substrate 43S is doped with N-type dopant to a resistivity of approximately 3.0 mΩ-cm. The concentration of N-type dopant falls to a concentration in the range 5×10 14 to 5×10 16 cm -3 (e.g., 6×10 15 cm -3 ) in drift region 43D and to a concentration in the range 3×10 14 to 3×10 15 cm -3 (e.g., 3×10 15 cm -3 ) in region of high resistivity 43HR. The dopant concentration of 6×10 15 cm -3 and 3×10 15 cm -3 in drift region 43D and region of high resistivity 43HR yield resistivities of 0.8 Ω-cm and 1.5 Ω-cm, respectively, for an N-channel device. The dopant concentration of region of high resistivity 43HR should be lower than the dopant concentration of delta layer 43LR. Gate 44 is doped with phosphorus ions at a concentration of 5×10 19 cm -3 (typically 20 Ω/sq.). (In a P-channel device, the gate may be doped with boron.)The bottom of the trench 48 is approximately 1.6 μm (alternatively in the range 1-3 μm) below the top surface, and the boundary between region 43HR and drift region 43D is approximately 2.6 μm (alternatively in the range 2-5 μm) below the surface. Epitaxial layer 47 is approximately 5.0 μm thick. FIG. 5B shows the dopant concentrations of MOSFET 40 at cross-section 5B--5B shown in FIG. 4. The dopant levels in substrate 43S and drift region 43D are the same as those shown in FIG. 5A. Similarly, the concentration of N-type dopant in region 43HR remains at 3×10 15 cm -3 , but region 43HR extends upward to within 1.2 μm of the top surface, or above the bottom of the trench. The concentration of dopant in P-body 42 increases from 6×10 14 cm -3 at the junction with region 43HR to approximately 1×10 17 cm -3 at the junction with source region 41. The concentration of N-type dopant in source region 41 increases from approximately 1×10 17 cm -3 at that level to 2×10 20 cm -3 at the top surface of the structure. It is apparent from FIGS. 5A and 5B that region of high resistivity 43HR extends around the bottom and side of trench 48 and includes the corner of trench 48 where the electric field normally reaches a maximum. FIG. 5C shows the dopant concentrations in MOSFET 40 at the cross-section designated 5C--5C in FIG. 4, which represents the center of the cell. Again, the dopant concentrations in substrate 43S and drift region 43D remain the same. P+ contact region 46 has a dopant concentration which reaches a maximum of approximately 5×10 18 cm -3 at the top surface of the device. Immediately below P+ region 46 is a portion of P-body region 42 which has a dopant concentration in the neighborhood of 2×10 16 cm -3 . Immediately below the P-body region 42 in the center of the cell is the delta layer 43LR, which may extend to the ordinary portions of drift region 43D, as indicated by the solid line in FIG. 4. Alternatively, a portion of region 43HR may separate delta layer 43LR from the ordinary portions of drift region 43D at the center of the cell. This is indicated by the dashed line in FIG. 4, and the dopant concentrations for this alternative embodiment are illustrated by the dashed line in FIG. 5C. Delta layer 43LR helps to ensure that the device breaks down in the region of the center of the cell rather than at a location adjacent to the trench, where breakdown may damage or destroy the gate oxide 45. Moreover, delta layer 43LR represents an area of low resistivity and therefore compensates to some extent for the higher resistivity of the region 43HR. Thus, the combination of region 43HR and delta layer 43LR provides an area of relatively high resistivity surrounding the trench and an area of relatively low resistivity at the center of the cell. FIGS. 6A-6J illustrate a process for fabricating a MOSFET in accordance with this invention. As shown in FIG. 6A, the process begins with an substrate 150, which may be 500 μm thick and have a resistivity of 3 mΩ-cm. A first N-epitaxial layer 151 and then a second N-epitaxial layer 152 are grown on the top surface of substrate 150 in succession. First N-epitaxial layer 151 is doped to a concentration of, for example, 6×10 15 cm -3 , and second N-epitaxial layer 152 is doped to a concentration of, for example, 3×10 15 cm -3 . Preferably, substrate 150 is not removed from the epi reactor in the course of growing epitaxial layers 151 and 152. Alternatively, instead of growing two epitaxial layers having different uniform concentrations of dopant, respectively, the concentration of N-type dopant can be reduced gradually and monotonically while at least a portion of the epitaxial layer is being grown, so as to form a region of high resistivity. For example, the concentration of dopant could be reduced gradually from the concentration in the substrate to a concentration of about 3×10 15 cm -3 near the surface (e.g., at a depth of 3 μm). The reduction can be performed according to a linear or some other function. A field oxide layer 153 is then grown on the top surface of N-epitaxial layer 152 by heating the structure in an oxidizing ambient such as oxygen or steam at 900-1100° C. As shown in FIG. 6B, field oxide layer 153 is patterned and etched from the active areas of the device. Field oxide layer 153 remains in the high-voltage termination at the outer edge of the die, and in regions to be used for busing the polysilicon gate. As shown in FIG. 6C, an oxide layer 154 400 Å thick is grown to prevent contamination, and the trench area is then patterned with photoresist. The trench is then etched to an appropriate depth, leaving a desired thickness of second N-epitaxial layer 152 below the bottom of the trench. As shown in FIG. 6D, oxide layer 154 and the photoresist are then removed. A gate oxide layer 155 is then grown on the top surface of the structure, including the trench. Gate oxide layer 155 is grown in dry oxygen including a chloride such as TCA (tricholoroethane). The thickness of gate oxide layer ranges from 80-2000 Å. As shown in FIG. 6E, a polysilicon gate 156 is deposited to fill and overflow the trench. This is preferably performed using a chemical vapor deposition process. Polysilicon gate 156 is then etched back to produce a planar surface. The die is masked to protect areas where the polysilicon gate 156 comes out of the trench to form a gate contact. Polysilicon gate 156 is doped with phosphorus to a sheet resistance of 20 Ω/sq. This doping may occur prior to or after the etchback. One method is to dope polysilicon gate 156 by "pre-depping" with POCl 3 before the trench is etched. Alternatively, the gate may be doped in situ while it is being formed. As shown in FIG. 6F, P-body 157 is implanted through gate oxide 155 using a blanket implant of boron at a dose of 5×10 13 cm -2 and an energy of 30-150 keV. P-body 157 is then driven in to 1.2 μm by heating 1-6 hours at 900-1100° C. in a nitrogen atmosphere. Alternatively, a mask can be used to limit the P-body implant to the active areas of the device. As shown in FIG. 6G, the top surface of oxide layer 155 is masked, and source region 158 is implanted at a dose of 4×10 15 to 1×10 16 cm -2 at an energy of 40-80 keV. Source region 158 is driven in at 900-1100° C. for 15-60 minutes. A BPSG layer 159 is then deposited on the top surface of the structure to a thickness of 3,000-10,000 Å. As shown in FIG. 6H, BPSG layer 159 and the underlying oxide are then patterned and etched using photoresist to form a contact mask. N delta layer 160 is then implanted through the contact mask. N delta layer 160 is implanted with phosphorus at a dose of 1×10 12 to 5×10 13 cm -2 and an energy of 60-250 keV. As shown in FIG. 6I, P+ contact region 161 is implanted through the same mask, using boron at a dose of 8×10 14 to 5×10 15 cm -2 and an energy of 20-80 keV. The structure is then subjected to a thermal treatment at 900-1000° C. for 15-30 minutes. This process activates the N delta layer 160 and flows the BPSG layer 159. As shown in FIG. 6J, a metal layer 162 is deposited by sputtering to a thickness of 1-4 μm. Metal layer 162 is preferably aluminum with 2% copper and 2% silicon. Metal layer 162 is then appropriately etched, and the structure is covered with a passivation layer (not shown) of Si 3 N 4 or BPSG. In the above-described process, the contact mask is used as a mask for implanting N delta layer 160 and P+ contact region 161. Alternatively, N delta layer 160 and P+ contact region 161 could each be implanted through its own mask. Also, the sequence of the implants may be altered. For example, N delta layer 160 may be implanted immediately following the implanting of P-body 157 (FIG. 6F) and before the implanting of source region 158). The delta layer may be implanted prior to the implanting and diffusion of the P-body region. If this is done, the delta layer diffuses during the body drive-in diffusion, increasing the depth of the lower boundary of the delta layer and the lateral spreading of the delta layer. If the delta layer is not to extend laterally to the trench, then its feature size at the time it is implanted must be reduced appropriately. As previously described, the delta layer may be introduced prior to or after the formation of the P-body or prior to or after the formation of the source. Regardless of the sequence in which the delta layer, P-body and source are formed, the trench etching and gate formation may take place at any point in the sequence, including after all of the implantations have been completed. For example, the P-body, source, shallow P+ and delta layer could be formed prior to the etching of the trench, and then the trench, gate oxide and gate could be fabricated. Alteratively, the etching of the trench could follow the source diffusion but precede the delta layer implant. By changing the sequence of these process steps, the basic structure of the MOSFET remains the same but the risk of cumulative misalignments among various features may increase, thereby restricting the cell density. Instead of forming the delta layer by implantation, the delta layer may be formed by increasing the concentration of dopant for a relatively short period of time while the epitaxial layer is being grown (e.g., by applying a short "pulse" of dopant. FIG. 6K illustrates several of these possibilities, the horizontal axis representing the distance from the substrate/epitaxial layer interface and the vertical axis representing dopant concentration during the growth of the epitaxial layer. The solid line-represents the "step function" embodiment illustrated in FIG. 6A, and the dashed line represents the gradual reduction of dopant described above. The cross-hatched figure represents a delta layer that is formed by applying a "pulse" of dopant while the epitaxial layer is being grown. Whether the delta layer is formed by implantation or during the growth of the epitaxial layer, it may extend laterally across the surface of a wafer, except where it may be interrupted by the gate trenches. This is shown in FIGS. 8A and 8B, for example, where delta layer 184 extends into the adjoining MOSFET cells on a die. Alternatively, a central P+ region, such as is shown in FIG. 2C and FIGS. 3A-3C may be substituted for or may be included with delta layer 43LP. In another alternative embodiment, both delta layer 43LP and the central P+ region are omitted. FIG. 7A shows an embodiment which includes a region of high resistivity 180 in conjunction with a delta layer 181 and a relatively deep central P+ region 182. The embodiment of FIG. 7B is similar except that central P+ region 183 is shallower than P+ region of FIG. 7A. In FIGS. 8A and 8B, a delta layer 184 extends to the side wall of the trench. FIG. 8A includes deep central P+ region 182; FIG. 8B includes shallower P+ region 183. To examine the performance of MOSFETs constructed in accordance with this invention, several simulated tests were performed using the two-dimensional device simulator Medici. The first device analyzed was a conventional 60 V device in the form of MOSFET 300 in FIG. 3A having a cell width of 9 μm (i.e., the distance from the center of the gate to the center of the cell was 4.5 μm). With a gate-to-source voltage V GS =10 V and with a drain-to-source voltage V DS =0.1 V, the drain current per unit of channel width I DS was 2.0×10 -6 A/μm. For a similar 7 μm cell MOSFET having the same V GS and V DS , the drain current per unit width I DS /W was 2.1×10 -6 A/μm. (I DS /W is the current per unit width measured parallel to the surface of the gate. Thus, for a square cell having a cell width Y cell and a gate width G, the total current that flows through the cell is equal to 4 I DS /W (Y cell -G).) Because of the increased packing density in the 7 μm device, the total current flowing through the 7 μm device was greater and represented approximately an 18% improvement in the specific on-resistance (i.e., the resistance per unit area of the device). Both the 7 μm and 9 μm cell width devices tested had a deep central P+ region (see FIG. 3A). This structure is impossible in a 5 μm cell device because the P+ region would touch the edge of the trench. As noted above, this leads to an unacceptably high threshold voltage and a severely "pinched" drift region of very high on-resistance. For this reason, a 5 μm cell device of the structure illustrated in FIG. 4 was tested. With V GS =10 V and V DS =0.1 V, the drain current I DS /W was equal to 1.8×10 -6 A/μm. Again, because of the increased packing density in a 5 μm cell device, this current corresponds to a 20% reduction in on-resistance per unit area as compared with the 7 μm cell device and a 40% reduction in on-resistance as compared with the 9 μm cell device. FIG. 9A illustrates the distribution of current in the 5 μm cell device in accordance with this invention. The location of P-body region 42 and gate 44 are shown in FIG. 9A. FIG. 9B illustrates the current distribution in the 9 μm cell device analyzed. The spaces between the flow lines in FIGS. 9A and 9B represent similar percentages of the total current. A comparison of FIGS. 9A and 9B indicates that the MOSFET fabricated in accordance with the invention had a more uniform current distribution. This tends to reduce the on-resistance of the device. The breakdown voltage of the 5 μm cell device was analyzed to see how it compared with the breakdown voltage of the 9 μm cell device. Again, the two-dimensional device simulator Medici was used. FIGS. 10A and 10B show the equipotential lines and the electric field contours, respectively, of the 9 μm cell device in the off state with V DS =60 V. Referring to FIG. 10B, the electric field at the bottom center of the trench (point A) and the corner of the trench (point B) were 26 V/μm and 36.2 V/μm, respectively. The equipotential lines and electric field contours for the 5 μm cell device are shown in FIGS. 11A and 11B, respectively. It is particularly important to note that the electric field at points A and B were 29.1 V/μm and 35.8 V/μm, respectively. A comparison with the corresponding values for the 9 μm cell device suggests that the breakdown potential of the 5 μm cell device is about the same. FIGS. 12A and 12B show the ionization rates for the 9 μm cell and 5 μm cell devices, respectively. The ionization rate shown for the 9 μm cell device in FIG. 12A yields an ionization integral of 0.78 at the junction between the deep central P+ region and the drift region. The data shown in FIG. 12B yield an ionization integral of 0.73 at the junction between the P-body and the drift region in the 5 μm cell device. Again, these data imply similar breakdown voltages for the two MOSFETs. Accordingly, the data shown in FIGS. 10A, 10B, 11A, 11B, 12A and 12B show that a 5 μm cell device fabricated in accordance with this invention has breakdown characteristics comparable to those of a conventional 9 μm cell device, and thus the improved on-resistance described above is not achieved at the cost of a reduced breakdown voltage. The embodiments described above are vertical trench MOSFETs, in which the substrate forms the drain and the drain contact is typically located at the bottom surface of the die. The principles of this invention are also applicable to so-called "quasi-vertical" MOSFETs wherein the drain contact is made at the top surface of the die. FIG. 13 illustrates a quasi-vertical MOSFET, similar to the MOSFET shown in FIG. 7B, which includes a drift region 312, a region of high resistivity 314 and a delta layer 316. The drain, however, is formed by an buried layer 318, which is located at the interface of P substrate 320 and drift region 312. A drain contact 306 at the top surface of the die is tied to buried layer 318 by means of an sinker 304. While the embodiments described above are N-channel MOSFETs, it will be apparent that the principles of the invention are also applicable to the P-channel MOSFETs. The specific embodiments described above are only illustrative of the broad principles of this invention and are not to be considered as limiting. The scope of this invention is defined only in the following claims.	A MOSFET switch with a gate formed in a trench has a drain which includes a region of relatively high resistivity adjacent the trench and a region of relatively low resistivity further away from the trench. The drain may also include a "delta" layer having even lower resistivity in a central region of the MOSFET cell. The high resistivity region limits the strength of the electric field at the edge of the trench (particularly where there are any sharp corners) and thereby avoids damage to the gate oxide layer. The central "delta" layer helps to insure that any breakdown will occur near the center of the MOSFET cell, away from the gate oxide, and to lower the resistance of the MOSFET when it is in an on condition.	7
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates to a solar cell apparatus, particularly to a solar cell apparatus having the transparent conducting layer with the structure as a plurality of nano-level well-arranged arrays. [0003] 2. Description of the Prior Art [0004] After the financial tsunami of 2008, a lot of global countries realize that it is necessary to develop the green energy industry, in order to become the important response of future national development and the promoting goal of industry. Therefore, the green energy industry has already become the global main motive source of economic development, and even become the prior industry developed by every advanced country at present. Taiwan also promotes the green energy industry in a more cost-effective manner at present, particularly regards the solar energy industry as the main green energy industry for the development in the future. [0005] The polysilicon solar cell is the main product of solar energy industry at present. However, the polysilicon material is very expensive, it is difficulty to make large-area product, thus it is unfavorable to be used in industry. In addition, its current conversion efficiency is very low, thus present academic research and industry turn to more research and development and use of thin film solar cell. The main consideration is to make the material with the larger area and bigger efficiency quickly. However, due to the thin film solar cell is too thin, the optical absorption path become too short, the efficiency of thin film solar cell produced by present technique is generally not high. Thus, there is a great improvement space for the research and development. [0006] In the U.S. Pat. No. 6,750,393, the three-dimensional photonic crystal is made at the back of solar cell, in order to obtain the effect of light trapping. However, its design and manufacturing is very difficult. When the photonic crystal is placed inside the solar cell, the photonic current is apt to be trapped inside, thus as to reduce the cell efficiency instead. [0007] The U.S. Pat. No. 7,482,532 providing the textured distributed Bragg reflector (DBR) is made at the back of solar cell, in order to obtain the effect of light trapping and high reflection rate. Its purpose is to substitute the metal reflection layer. However, this DBR structure is unable to provide the anti-reflection effect actually. Moreover, this DBR structure includes an insulation layer, thus it is apt to increase the resistance value instead. [0008] In the prior art of the U.S. Pat. No. 6,858,462, the etching periodic structure of silicon substrate surface is used. Although the light trapping effect can be achieved, the surface defect is apt to be produced because of etching process. The electron and electric hole are extremely easy to be trapped onto the surface, so that the current is unable to be extracted effectively, and the cell efficiency will be reduced. [0009] Therefore, in order to produce better solar cell, and offer better solar cell production technology to the industry, it is necessary to develop innovative solar cell production process technology, so as to improve the cell efficiency of solar cell, and reduce the manufacturing cost of solar cell. SUMMARY OF THE INVENTION [0010] The invention relates to a solar cell apparatus having the transparent conducting layer with the structure as a plurality of nano-level well-arranged arrays with a plurality of certain defect areas, wherein the plurality of nano-level well-arranged arrays is a periodic or a quasi-periodic. The invention comprises a transparent substrate. A transparent conducting electrode is formed on the transparent substrate, and a photoactive layer is formed on the transparent conducting electrode. The transparent conducting electrode has the structure as a plurality of nano-level well-arranged arrays with a plurality of certain defect areas, wherein the plurality of nano-level well-arranged arrays is a periodic or a quasi-periodic, including the types of rod-shaped, trapezium-shaped, cone-shaped, tapered-cone-shaped, and nipple-shaped and so on. [0011] The invention can solve the problem that due to the thickness of thin film solar cell and photodetector is too thin, thus the effective absorption length is unable to be provided. [0012] The invention uses the structure as a plurality of nano-level well-arranged arrays, wherein the plurality of nano-level well-arranged arrays is a periodic or a quasi-periodic with a plurality of certain defect areas, to trap the light in the limited thickness of thin film solar cell, and increase the contact area of photoactive layer and electrode. [0013] The nano-structure of the invention can provide the anti-reflection effect, and increase the photons entering into the photoactive layer. [0014] The invention uses the transparent conducting electrode to form the nano-structure, thus the electron-hole pair generated from the photoactive layer is easier to be collected by the electrode, and finally can increase the internal quantum efficiency. [0015] The invention can increase the contact area of solar cell material and transparent conducting electrode, and the electrical current can be extracted more efficiently due to the increase for the contact area of electrode and photoactive layer. [0016] The invention can be used in the photonic crystal of large-area process, and use the light trapping feature and anti-reflection effect of photonic crystal to various thin film solar cells and photodetectors, in order to increase the photon absorption rate and reach higher photovoltaic conversion efficiency. [0017] Therefore, the advantage and spirit of the invention can be understood further by the following detail description of invention and attached figures. BRIEF DESCRIPTION OF THE DRAWINGS [0018] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: [0019] FIG. 1A is a graph illustrating the first embodiment of the invention. [0020] FIG. 1B is a graph illustrating the structure of transparent conducting electrode for the first embodiment of the invention. [0021] FIG. 2A is a graph illustrating the second embodiment of the invention. [0022] FIG. 2B is a graph illustrating the structure of transparent conducting electrode for the second embodiment of the invention. [0023] FIG. 3A is a graph illustrating the third embodiment of the invention. [0024] FIG. 3B is a graph illustrating the structure of transparent conducting electrode for the third embodiment of the invention. [0025] FIG. 4A is a graph illustrating the fourth embodiment of the invention. [0026] FIG. 4B is a graph illustrating the structure of transparent conducting electrode for the fourth embodiment of the invention. [0027] FIG. 5A is a graph illustrating the fifth embodiment of the invention. [0028] FIG. 5B is a graph illustrating the structure of transparent conducting electrode for the fifth embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT [0029] The invention relates to a solar cell apparatus having the transparent conducting layer with the structure as a plurality of nano-level well-arranged arrays with a plurality of certain defect areas, wherein the plurality of nano-level well-arranged arrays is a periodic or a quasi-periodic. The first embodiment is shown in FIG. 1A . A transparent substrate 101 is provided at first. The glass or sapphire is selected as the transparent substrate 101 . [0030] As shown in FIG. 1A , the chemical vapor deposition (CVD) is used to form a transparent conducting electrode (TCO) 102 on the transparent substrate 101 . The material of transparent conducting electrode 102 includes the indium tin oxide (ITO) and aluminum zinc oxide (AZO), which has the conduction and light penetration property. The polystyrene spheres colloidal lithography and physical or chemical etching method are used to form the rod-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 102 . [0031] As shown in FIG. 1A again, the chemical vapor deposition (CVD) is used to form a photoactive layer 103 on the transparent conducting electrode 102 . The photoactive layer 103 is mainly a material which can form the electron and electric hole, including solar cell material. The crystalline silicon and amorphous silicon can be formed on the transparent conducting electrode 102 by the chemical vapor deposition. [0032] FIG. 1B is a graph illustrating the rod-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 102 , which has symmetrical arrangement and asymmetrical arrangement, thus it has the shape of cyclic arrangement. [0033] The second embodiment of the invention is shown in FIG. 2A . A transparent substrate 201 is provided at first. The glass or sapphire is selected as the transparent substrate 201 . [0034] As shown in FIG. 2A , the chemical vapor deposition is used to form a transparent conducting electrode 202 on the transparent substrate 201 . The material of transparent conducting electrode 202 includes the indium tin oxide (ITO) and aluminum zinc oxide (AZO), which has the conduction and light penetration property. The polystyrene spheres colloidal lithography and physical or chemical etching method are used to form the trapezium-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 202 . [0035] As shown in FIG. 2A again, the chemical vapor deposition is used to form a photoactive layer 203 on the transparent conducting electrode 202 . The photoactive layer 203 is mainly a material which can form the electron and electric hole, including solar cell material. The crystalline silicon and amorphous silicon can be formed on the transparent conducting electrode 202 by the chemical vapor deposition. [0036] FIG. 2B is a graph illustrating the trapezium-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 202 , which has symmetrical arrangement and asymmetrical arrangement, thus it has the shape of cyclic arrangement. [0037] The third embodiment of the invention is shown in FIG. 3A . A transparent substrate 301 is provided at first. The glass or sapphire is selected as the transparent substrate 301 . [0038] As shown in FIG. 3A , the chemical vapor deposition is used to form a transparent conducting electrode 303 on the transparent substrate 301 . The material of transparent conducting electrode 303 includes the indium tin oxide (ITO) and aluminum zinc oxide (AZO), which has the conduction and light penetration property. The polystyrene spheres colloidal lithography and physical or chemical etching method are used to form the cone-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 303 . [0039] As shown in FIG. 3A again, the chemical vapor deposition is used to form a photoactive layer 303 on the transparent conducting electrode 303 . The photoactive layer 303 is mainly a material which can form the electron and electric hole, including solar cell material. The crystalline silicon and amorphous silicon can be formed on the transparent conducting electrode 303 by the chemical vapor deposition. [0040] FIG. 3B is a graph illustrating the cone-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 303 , which has symmetrical arrangement and asymmetrical arrangement, thus it has the shape of cyclic arrangement. [0041] The fourth embodiment of the invention is shown in FIG. 4A . A transparent substrate 401 is provided at first. The glass or sapphire is selected as the transparent substrate 401 . [0042] As shown in FIG. 4A , the chemical vapor deposition is used to form a transparent conducting electrode 404 on the transparent substrate 401 . The material of transparent conducting electrode 404 includes the indium tin oxide (ITO) and aluminum zinc oxide (AZO), which has the conduction and light penetration property. The polystyrene spheres colloidal lithography and physical or chemical etching method are used to form the tapered-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 404 . [0043] As shown in FIG. 4A again, the chemical vapor deposition is used to form a photoactive layer 403 on the transparent conducting electrode 404 . The photoactive layer 403 is mainly a material which can form the electron and electric hole, including solar cell material. The crystalline silicon and amorphous silicon can be formed on the transparent conducting electrode 404 by the chemical vapor deposition. [0044] FIG. 4B is a graph illustrating the tapered-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 404 , which has symmetrical arrangement and asymmetrical arrangement, thus it has the shape of cyclic arrangement. [0045] The fifth embodiment of the invention is shown in FIG. 5A . A transparent substrate 501 is provided at first. The glass or sapphire is selected as the transparent substrate 501 . [0046] As shown in FIG. 5A , the chemical vapor deposition is used to form a transparent conducting electrode 505 on the transparent substrate 501 . The material of transparent conducting electrode 505 includes the indium tin oxide (ITO) and aluminum zinc oxide (AZO), which has the conduction and light penetration property. The polystyrene spheres colloidal lithography and physical or chemical etching method are used to form the nipple-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 505 . [0047] As shown in FIG. 5A again, the chemical vapor deposition is used to form a photoactive layer 503 on the transparent conducting electrode 505 . The photoactive layer 503 is mainly a material which can form the electron and electric hole, including solar cell material. The crystalline silicon and amorphous silicon can be formed on the transparent conducting electrode 505 by the chemical vapor deposition. [0048] FIG. 5B is a graph illustrating the nipple-shaped photonic crystal or quasi-photonic crystal on the transparent conducting electrode 505 , which has symmetrical arrangement and asymmetrical arrangement, thus it has the shape of cyclic arrangement. [0049] The invention makes the photonic crystal or quasi-photonic crystal with cyclic structure on the transparent conducting electrode of solar cell, in order to produce the light diffraction and the light scattering. The incident light can diffract and scatter in the solar cell, increase the light path and increase its absorption, and obtain the light trapping effect in the photoactive layer. This structure has the anti-reflection effect on the surface, which causes the increase of incident light. The invention uses the transparent conducting electrode to form the structure as the plurality of nano-level well-arranged arrays with a plurality of certain defect areas, wherein the plurality of nano-level well-arranged arrays is a periodic or a quasi-periodic, thus the electron-hole pair generated from the photoactive layer is easier to be collected by the electrode. The invention can increase the contact area of electrode and photoactive layer, and the electrical current can be extracted more efficiently and the internal quantum efficiency can be increased effectively. Summarized from the above-mentioned description, the invention can be applied to and designed in various solar cell materials and photodetectors, in order to increase the absorption efficiency of solar light. [0050] The invention uses the nano-level well-arranged arrays to trap the light in the limited thickness of thin film solar cell, and increase the contact area of photoactive layer and electrode. The invention can solve the problem that due to the thickness of thin film solar cell and photodetector is too thin, thus the effective absorption length is unable to be provided. [0051] It is understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be construed as encompassing all the features of patentable novelty that reside in the present invention, including all features that would be treated as equivalents thereof by those skilled in the art to which this invention pertains.	The invention discloses an apparatus for enhancing light absorption of solar cells and photodetectors by diffraction. The invention comprises the structure as the plurality of nano-level well-arranged arrays with a plurality of certain defect areas including the shapes of rod, tapered-cone, and cone, which diffracts incident light to oblique angles for light trapping. Surface reflection can also be reduced for either broadband or narrow band spectral absorption. The increased contact area between the transparent conducting layer and photoactive layer is beneficial for current extraction, which increases the internal quantum efficiency (IQE).	8
FIELD OF THE INVENTION [0001] The invention relates to devices and methods for converting thermal energy into kinetic energy especially for the production and/or storage of electrical energy. BACKGROUND OF THE INVENTION [0002] Given society's ever increasing energy consumption, there is a resultant high demand for energy. Since the earth's natural energy reserves are becoming depleted and prices of oil and natural gas are relatively high, there is a demand for new sources of energy. [0003] There have been attempts to convert existing forms of energy into forms of energy that can be used to satisfy our energy needs. Many of these processes harness energy sources that are replenished by natural processes. These energy sources are referred to as renewable energy sources. An example is solar energy where energy from the sun in the form of heat energy and light energy is converted into electrical energy. However, sunlight is a weak energy source compared to traditional energy sources such as fossil fuels. It is very difficult to harness sunlight efficiently for conversion into useful forms of energy. It is particularly difficult to use sunlight effectively for home energy needs. Energy requirements are usually highest when it is dark and cold. This is precisely when solar energy is least effective. Solar energy becomes much more useful when we change it to another form. Sunlight can be converted to electricity by photovoltaic cells. However, this conversion is inefficient and high in cost. Also, some types of photovoltaic solar cells contain mercury that is highly toxic. [0004] Other renewable energy sources have the drawback of being environmentally unfriendly. For example, wind power plants can damage local animal populations. Also, hydroelectric dams can cause problems such as the creation of large reservoirs. This can upset the ecological balance of the surrounding environment. This has the consequences of disrupting local animal populations and their migration patterns. Dams also affect fish populations. [0005] It would therefore be desirable to be able to harness existing forms of energy in an effective and environmentally friendly manner. It has been recognized that it would be desirable to convert naturally occurring heat sources into useable forms of energy. There have been a number of attempts to convert low-level heat sources into mechanical energy. These methods employ the principle of expansion and contraction of a working fluid, utilizing a heat source to add and remove heat from the working fluid. These methods have the drawback of failing to obtain a sufficient concentration of heat to activate the process in an efficient manner. Such methods to date have failed to produce an economically viable energy generation process. [0006] U.S. Pat. No. 4,134,265 provides an example of such a prior art process. This patent discloses a method for developing gas pressure to drive an engine. The method involves the use of a plurality of separate containers in a closed circuit. The tanks communicate with heat exchangers that are arranged in combination with certain controls to create pressure variations on a given volume of gas by varying the gas temperatures. The tanks are used in pairs with the gas in one tank being cooled while the other gas in the other tank is heated to develop a pressure differential therebetween. Controlled communication between the tanks produces flow to one of the tanks with an increase in mass of gas therein and followed by a second development of gas differential pressure. The gas is released for communication with a piston to produce a work stroke. [0007] U.S. Pat. No. 3,995,429 provides another example of a prior art process that fails to produce an economically viable energy generation system. The. patent discloses a system of generating electric power derived from the energy of the sun, the atmosphere, the ground or the heat stored in ground water, whichever provides the greatest temperature differential with another adjacent source of energy. The apparatus generates a fluid vapour pressure for the operation of a vapour engine and includes at least three heat sources. One of the sources is a solar absorber for absorbing the heat from the sun. A second source is a heat exchanger which dissipates the heat of the fluid to the atmosphere. A third source is a radiator positioned in the ground water. A fourth source for transforming ground or geothermal heat to the fluid also for transferring the heat of the ground water to the fluid is provided. Other well-known heat sources may be substituted where available. Valve connecting means are operated to connect any two of the four heat sources in a closed cycle system for the transfer of heat from one source to another. Pumping means are provided for forcing fluid through the system to a source where the fluid is vaporized. A transducer such as a turbine or piston engine connected to the heat source vaporizes the fluid that produces the mechanical power. [0008] There have been attempts to harness naturally occurring temperature gradients. An example is Ocean Thermal Energy Conversion. A significant amount of financial resources have been invested in pilot plants to harness the surface heat of the world's oceans by making use of temperature gradients between the warm surface and cold depths. This has not yielded an economically viable method for energy production. [0009] There is therefore a need for an apparatus and method for converting thermal energy into mechanical and electrical energy in an environmentally friendly efficient, and economically viable manner. There is a need for such an apparatus and method that can utilize a very low temperature differential to produce energy efficiently. SUMMARY OF THE INVENTION [0010] The invention provides a method of extracting a differential in thermal energy between a first thermal source and a second thermal source and converting this energy into mechanical energy that can be used to generate electrical energy for energy storage or direct use or to feed into a power grid. The thermal sources are put in fluid communication with two vessels containing a gas under pressure. The thermal sources have thermal values that are different than the thermal values of the vessels. The thermal sources are used to alternately increase the temperature and pressure in one of the vessels and decrease the temperature and pressure in the other vessel. A pressure driven actuator is moved in a single direction by the resultant pressure released by the first vessel and suction from the second vessel. [0011] According to another aspect of the invention, there is provided an apparatus for extracting a differential in thermal energy between a first thermal source and a second thermal source and converting this energy into mechanical energy is provided. The apparatus has first and second vessels that include a gas under pressure. The thermal sources are in fluid communication with the two vessels. The thermal sources have thermal values that are different than the thermal values of the vessels. The thermal sources are adapted to alternately increase the temperature and pressure in one of the vessels while decreasing the temperature and pressure in the other vessel. A pressure driven actuator coupled to the vessels and is moved in a single direction by pressure released by the first vessel and suction from the second vessel. The pressure driven actuator may be coupled to a piston and cylinder assembly or a rotary actuator in order to transfer mechanical energy thereto. [0012] An apparatus for converting a differential in thermal energy between a first thermal source having a thermal conducting fluid and a second thermal source having a thermal conducting fluid, the apparatus comprising: a first vessel for containing a gas under pressure, the first vessel being in fluid communication with said first and second thermal sources; a second vessel for containing a gas under pressure, the second vessel being in fluid communication with said first and second thermal sources; a plurality of cooperating valves for alternately regulating a flow of thermal conducting fluid from the first and second thermal sources to the first and second vessels, the plurality of cooperating valves alternating between first and second operating positions, the plurality of cooperating valves permitting a flow of thermal conducting fluid from the first thermal source to the first vessel and from the second thermal source to the second vessel in first operating position, the plurality of cooperating valves preventing a flow of thermal conducting fluid from the first thermal source to the second vessel and from the second thermal source to the first vessel in the first operating position, the plurality of cooperating valves permitting a flow of thermal conducting fluid from the first thermal source to the second vessel and from the second thermal source to the first vessel in the second operating position, the plurality of cooperating valves preventing a flow of thermal conducting fluid from the first thermal source to the first vessel and from the second thermal source to the second vessel in the second operating position; a pressure driven actuator in fluid communication with the first and second vessels whereby the actuator is driven into reciprocating motion between a first position and a second position by alternating positive pressure and negative pressure from the first and second vessels wherein positive pressure from the first vessel coupled with negative pressure from the second vessel when the plurality of cooperating valves is in the first operating position drives the actuator to the first position and negative pressure from the first vessel coupled with positive pressure form the second vessel when the plurality of cooperating valves is in the second operating position drives the actuator to the second position. [0017] According to another aspect of the present invention there is provided a method for converting a differential in thermal energy to kinetic energy comprising the following steps: providing first and second vessels containing a gas under pressure, the gas under pressure being of a temperature T; providing a first thermal source and a second thermal source, the first thermal source housing a thermal transfer fluid of a temperature above T and the second thermal source housing a thermal transfer fluid of a temperature below T. delivering the thermal transfer fluid from the first thermal source to the first vessel thereby raising the pressure of the gas in the first vessel; delivering the thermal transfer fluid from the second thermal source to the second vessel thereby lowering the pressure of the gas in the second vessel; delivering gas under pressure from the first vessel to a pressure activated actuator and applying suction from the second vessel to the pressure activated actuator thereby causing the pressure activated actuator to move in a first direction. BRIEF DESCRIPTION OF THE DRAWINGS [0023] In drawings which illustrate by way of example only a preferred embodiment of the invention, [0024] FIG. 1 is a schematic illustration of a preferred embodiment of the present invention; [0025] FIG. 2 is a longitudinal cross-sectional view taken along lines 2 - 2 of FIG. 1 of a first vessel of the present invention; [0026] FIG. 3 is a longitudinal cross-sectional view taken along lines 3 - 3 of FIG. 1 of a second vessel of the present invention; [0027] FIG. 4 is a front view of a first thermal source of the present invention; [0028] FIG. 5 is a front view of a second thermal source of the present invention; [0029] FIG. 6 is a front view with portions cut away showing a pneumatic cylinder of the present invention; [0030] FIG. 7 is a schematic illustration of a first side of reversing transmission of the present invention; [0031] FIG. 8 is a schematic illustration of a second side of a reversing transmission of the present invention; and [0032] FIG. 9 is a schematic illustration of an alternate embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0033] The present invention provides an apparatus for converting a differential in thermal energy between two thermal sources into mechanical energy that can be used for a wide range of applications known to a person skilled in the art including the generation and storage of electrical energy. The invention also relates to a method of converting a differential in thermal energy between two thermal sources into mechanical energy. The method can be carried out with the apparatus of the present invention. [0034] A preferred embodiment of the present is shown in FIG. 1 . Apparatus 1 includes a first vessel 2 and a second vessel 4 . Each of the two vessels is preferably a sealed container that defines a chamber therein for containing a gas under pressure. As shown in FIGS. 2 and 3 , the first vessel 2 defines a chamber 3 and the second vessel 4 defines a chamber 5 . The vessels contain the gas under pressure in the chambers. The vessels are shown in lateral cross section in FIG. 1 and in longitudinal cross-section in FIGS. 2 and 3 . Each of the vessels preferably has an insulating jacket 72 for preventing thermal exchange with the ambient environment. [0035] The first vessel 2 has heat exchange conduit 10 located in the chamber 3 . The conduit 10 is preferably coiled copper tubing that is adapted to conduct a fluid. Other conduits known in the art to have favourable heat exchanging properties may also be employed in alternate embodiments. The conduit 10 has a first end 30 that communicates with the exterior of the vessel 2 through an opening 31 defined by the vessel 2 . The conduit 10 has a second end 32 that communicates with the exterior of the vessel 2 through an opening 33 defined by the vessel 2 . Similarly, the second vessel 4 has heat exchange conduit 12 located in the chamber 5 . The conduit 12 is also preferably coiled copper tubing that is adapted to conduct a fluid. Again, other conduits known in the art to have favourable heat exchanging properties may also be employed in alternate embodiments. The conduit 12 has a first end 34 that communicates with the exterior of the vessel 4 through an opening 35 defined by the vessel 4 . The conduit 12 has a second end 36 that communicates with the exterior of the vessel 4 through an opening 37 defined by the vessel 12 . Vessel 2 has a pressure sensor 102 . Vessel 4 has a pressure sensor 104 . [0036] The apparatus 1 further includes a first thermal unit 6 and a second thermal unit 8 . The thermal units are shown in FIGS. 1, 4 and 5 . Each of the thermal units is preferably a container that can receive a thermal delivery fluid. Preferably, the container is an insulated container that is of metal, plastic or fibreglass construction. Preferably, each of the thermal units defines a channel running therethrough for passage of the thermal conducting fluid. The thermal delivery fluid is preferably an environmentally suitable fluid of the type required in ground source closed loop heat pumps. However, other fluids with good thermal conductivity properties known in the art may also be used in other embodiments. [0037] The thermal units 6 , 8 preferably have a heat exchanger that is in thermal communication with the thermal fluid in order to transfer the temperature of the thermal unit to the thermal fluid. The thermal source can be any medium that is capable of storing or transferring thermal energy. Examples of acceptable thermal sources for the purposes of the present invention include ambient outside air, outside soil, water heated by energy produced by natural gas combustion, wood combustion, solar energy or energy provided by a thermal heat pump. The first thermal unit preferably has a plurality of thermal sources 77 , 78 , 79 while the second thermal unit thermal unit preferably has a plurality of thermal sources 82 , 83 , 84 . As shown in FIG. 4 , the thermal source 77 can be outside air with a heat exchanger coil in direct contact with the air. The thermal source 78 in such a case could be a hot water tank heated by natural gas, wood combustion, solar energy or a geothermal heat pump. In this case, there would be two heat exchangers in the tank. [0038] A first heat exchanger would transfer heat to the thermal fluid and a second heat exchanger would be connected to the heat source. Thermal source 79 could be direct contact heat exchanger embedded in soil or a body of water. As shown in FIG. 5 , thermal source 82 can be outside air with a heat exchanger coil in direct contact with the ambient air. The thermal source 83 could be a cool water tank cooled by a geothermal heat pump operating in reverse by extracting heat from the thermal fluid, The thermal source 84 could be a direct contact heat exchanger thermal source embedded in soil or a body of water. [0039] Preferably, the first thermal unit 6 uses thermal sources that provide a warm thermal source while the second thermal unit 8 preferably uses thermal sources that provide a cold thermal source. In other embodiments, it is possible that the thermal unit 8 contains the warm thermal sources while thermal unit 6 contains the cold thermal sources. A controller 70 controls from which of the compartments thermal conducting fluid will be dispensed. [0040] A thermal fluid conducting conduit 42 communicates between the thermal source 6 and the first vessel 2 . The conduit 42 further communicates between thermal unit 6 and the second vessel 4 . A fork 43 in the conduit 42 separates the conduit into a first branch leading to the first vessel 2 and a second branch leading to the second vessel 4 . The conduit 42 is received by in-pipe 86 that leads into the first end 30 of the thermal exchange conduit 10 . The conduit 42 is also received by in-pipe 94 that leads into the first end 34 of the heat exchange conduit 12 . A thermal fluid-conducting conduit 44 communicates between the thermal source 8 and the second vessel 4 . The conduit 44 further communicates between thermal unit 8 and the first vessel 2 . A fork 45 in the conduit 44 separates the conduit into a first branch leading to the first vessel 2 and a second branch leading to the second vessel 4 . The conduit 44 is received by in-pipe 96 that leads into the first end 34 of the heat exchange conduit 12 . The conduit 44 is also received by in-pipe 88 that leads into the first end 30 of the heat exchange conduit 10 . [0041] A thermal fluid-conducting conduit 38 communicates between the first vessel 2 and the thermal source 8 . The conduit 38 further communicates between the second vessel 4 and the thermal source 8 . A fork 39 in the conduit 38 separates the conduit into a branch leading from the first vessel 2 and another branch leading from the second vessel 4 . The conduit 38 is received by out-pipe 92 that leads from the second end 32 of the heat exchange conduit 10 . The conduit 38 is also received by out-pipe 100 that leads from the second end 36 of the heat exchange conduit 12 . A thermal fluid-conducting conduit 40 communicates between the first vessel 2 and the thermal source 6 . The conduit 40 further communicates between the second vessel 4 and the thermal source 6 . A fork 41 in the conduit 40 separates the conduit into a branch leading from the first vessel 2 and another branch leading from the second vessel 4 . The conduit 40 is received by out-pipe 90 that leads from the second end 32 of the heat exchange conduit 10 . The conduit 40 is also received by out-pipe 98 that leads from the second end 36 of the heat exchange conduit 12 . [0042] The thermal fluid conducting conduits are preferably made of insulated synthetic polymer or metal tubing which meets the standards of local building codes. [0043] A first valve 14 controls the flow of fluid from the thermal unit 6 to the conduit 10 . A second valve 26 controls the flow of fluid from the thermal unit 6 to the conduit 12 . A third valve 22 controls the flow of fluid from the thermal unit 8 to the conduit 10 . A fourth valve 18 controls the flow of fluid from the thermal unit 8 to the conduit 12 . A fifth valve 16 controls the flow of fluid from the conduit 10 to the thermal unit 6 . A sixth valve 24 controls the flow of fluid from the conduit 10 to the thermal unit 8 . A seventh valve 28 controls the flow of fluid from the conduit 12 to the thermal unit 6 . An eighth valve 20 controls the flow of fluid from the conduit 12 to the thermal unit 8 . Preferably the valves are solenoid valves although other valves known in the art may also be employed. Controller 70 is operatively connected to the valves for opening and closing the valves as required to carry out the method of the present invention. The eight valves described herein together with the controller comprise a plurality of cooperating valves for alternately regulating a flow of thermal energy from the first and second thermal sources to the first and second vessels. [0044] Preferably, pump 46 and pump 48 pump the thermal fluid through the thermal fluid conducting conduits. The pumps 46 , 48 are preferably circulating pumps of the type used in solar or geothermal applications. [0045] Vessel 2 further defines an opening 53 . A pressure conduit 54 is received in the opening 53 and communicates between the chamber 3 and the exterior of the vessel 2 for delivering gas from the chamber 3 to the exterior and vice versa. Similarly vessel 4 further defines an opening 55 . A pressure conduit 56 communicates between the chamber 5 and the exterior of the vessel 4 for delivering gas from the chamber to the exterior and vice versa. [0046] As shown in FIG. 6 , each of the pressure conduits 54 , 56 preferably communicates with pneumatic cylinder 58 and pneumatic cylinder 60 . The pneumatic cylinder 58 has a piston 74 moveably received therein while the pneumatic cylinder 60 has a piston 76 moveably disposed therein. The pneumatic cylinder 58 defines a first chamber 106 and a second chamber 108 . Similarly, the pneumatic cylinder 60 defines a first chamber 110 and a second chamber 112 . The piston 74 has a piston rod 73 while the piston 76 has a piston rod 75 . Both piston rods are attached to a connecting member 80 as shown in FIG. 5 . A valve 50 is located in the pressure conduit 54 between the vessel 2 and the pneumatic cylinders for regulating gas flow. Similarly, valve 52 is located in the pressure conduit 56 between the vessel 4 and the pneumatic cylinders for regulating gas flow. [0047] Connecting member 80 is preferably coupled to a reversing transmission known in the art. The reversing transmission can be coupled to a generator according to methods well known in the art. [0048] An example of a basic reversing transmission is shown in FIGS. 7 and 8 . These Figures show opposite sides of a flywheel 64 coupled to sprockets 116 and 126 respectively. The transmission includes sprocket pulleys 118 and 128 . Transmission chains 120 and 130 are attached to the sprockets 116 and 146 and to the pulleys 118 and 128 respectively. The flywheel 64 is coupled to drive pulley 122 of a generator 124 by way of drive belt 126 . [0049] An alternate embodiment of the invention is shown in FIG. 9 . Vessel 2 is connected to the pressure conduit 54 . Pressure conduit 54 feeds into pressure conduits 130 and 132 . Valve 50 is located between conduit 54 and the conduits 130 and 132 . Similarly, vessel 4 is connected to the pressure conduit 56 . Pressure conduit 56 feeds into pressure conduits 134 and 136 . Valve 52 is located between conduit 56 and the conduits 134 and 136 . Valve 138 is located at a junction between conduit 130 and conduit 134 . Similarly, valve 140 is located at a junction between conduit 132 and conduit 136 . Conduit 130 and conduit 134 join to form conduit 152 that preferably leads to the ports of a double rack rotary actuator. Similarly, conduit 132 and conduit 136 join to form conduit 150 that preferably leads to the ports of the double rack rotary actuator. [0050] In its operation, the apparatus reciprocates between a first operating position and a second operating position thereby driving the pressure-activated actuator into reciprocal motion. This reciprocal motion can be translated into various forms of energy. For example, when the pressure-activated actuator is a pneumatic cylinder the motion can be converted into mechanical or kinetic energy that can in turn be converted into electric potential energy by way of coupling the pneumatic cylinder to a generator. [0051] The controller 70 controls the opening and closing of the valves of the plurality of cooperating valves. To begin the cycle whereby the apparatus moves to the first operating position, the controller opens valve 14 and closes valve 26 so that warm thermal fluid from the thermal unit 6 flows through thermal fluid conduit 42 to in-pipe 86 and into the heat exchange conduit 10 of the vessel 2 . As the warm thermal fluid flows through the conduit 10 in the chamber 3 , heat is transferred from the conduit to the surrounding gas in the chamber 3 . This causes the pressure of the gas to increase. An acceptable pressure range for the purposes of the invention of the gases is approximately 10 p.s.i to 500 p.s.i. The controller opens valve 16 and closes valve 24 so that the thermal fluid can flow through the out-pipe 90 through the thermal fluid conduit 42 and back to the thermal unit 6 where the thermal fluid is re-heated. [0052] In addition to opening valve 14 and closing valve 26 , the controller simultaneously opens valve 18 and closes valve 22 so that cool thermal fluid from the thermal unit 8 flows through thermal fluid conduit 44 to in-pipe 96 and into the heat exchange conduit 12 of the vessel 4 . As the cool thermal fluid flows through the conduit 12 in the chamber 5 , heat is transferred from the surrounding gas in the chamber 5 to the conduit. This causes the pressure of the gas to decrease. The controller opens valve 20 and closes valve 28 so that the thermal fluid can flow through the out-pipe 100 . The thermal fluid flows through thermal fluid conduit 38 and back to the thermal unit 8 where the thermal fluid is re-cooled. [0053] When maximum thermal transfer has occurred, in the two vessels after about three seconds, the controller 70 will open the pressure valve 50 . The increased pressure in the vessel 2 will cause the gas from the chamber 3 to flow through the pressure conduit 54 and into the first chamber 106 of the pneumatic cylinder 58 and the first chamber 110 of the pneumatic cylinder 60 . At the same time, the controller opens the pressure valve 52 . The decreased pressure in the vessel 4 will cause the gas from the second chamber 112 of the pneumatic cylinder 60 and the second chamber 108 of the pneumatic cylinder 58 to flow through the pressure conduit 56 and into the chamber 5 of the vessel 4 . [0054] In both cases, the gas flow will be in the same direction thereby causing the pistons 74 , 76 to move in the same direction. The movement of the pistons causes the piston rods and the connecting member 80 to move in the same lateral direction. The movement of the connecting member 80 causes the transmission chain 120 to move. The transmission chain 120 in turn drives the sprocket 116 and the flywheel 64 . Energy from the turning of the flywheel can be transferred to the generator 124 . [0055] When the pistons 74 , 76 have reached their maximum travel, a sensor at the front of the cylinder 58 will cause the valves 50 , 52 to close. The pressure conduits have large enough diameters so as not to restrict the flow to and from the vessels 2 , 4 which would reduce efficiency. For example, in an embodiment that has a diameter of 1.5 inches for cylinders 58 , 60 , the pressure conduits would preferably have a minimum diameter of about 0.75 inch. [0056] The cycle whereby the apparatus moves to the second operating position is the direct reverse of the cycle whereby the apparatus moves to the first operating position. To begin the cycle whereby the apparatus moves to the second operating position, the controller opens valve 26 and closes valve 14 is so that warm thermal fluid from the thermal unit 6 flows through thermal fluid conduit 42 to in-pipe 94 and into the heat exchange conduit 12 of the vessel 4 . As the warm thermal fluid flows through the conduit 12 in the chamber 5 , heat is transferred from the conduit to the surrounding gas in the chamber 5 . This causes the pressure of the gas to increase. The controller opens valve 28 and closes valve 20 so that the thermal fluid can flow through the out-pipe 98 . The thermal fluid flows through thermal fluid conduit 40 and back to the thermal unit 6 where the thermal fluid is re-heated. [0057] In addition to opening valve 26 and closing valve 14 , the controller simultaneously opens valve 22 and closes valve 18 so that that cool thermal fluid from the thermal unit 8 flows through thermal fluid conduit 44 to in-pipe 88 and into the heat exchange conduit 10 of the vessel 2 . As the cool thermal fluid flows through the conduit 10 in the chamber 3 , heat is transferred from the surrounding gas in the chamber 3 to the conduit 10 . This causes the pressure of the gas to decrease. The controller opens valve 24 and closes valve 16 so that the thermal fluid can flow through the out-pipe 92 . The thermal fluid flows through thermal fluid conduit 38 and back to the thermal unit 8 where the thermal fluid is re-cooled. [0058] When maximum thermal transfer has occurred, in the two vessels after about three seconds, the controller 70 will open the pressure valve 52 . The increased pressure in the vessel 4 will cause the gas from the chamber 5 to flow through the pressure conduit 56 and into the second chamber 112 of the pneumatic cylinder 60 and the second chamber 108 of the pneumatic cylinder 58 . At the same time, the controller opens the pressure valve 50 . The decreased pressure in the vessel 2 will cause the gas from the first chamber 110 of the pneumatic cylinder 60 and the first chamber 106 of the pneumatic cylinder 58 to flow through the pressure conduit 54 and into the chamber 3 of the vessel 2 . [0059] Once again, in both cases, the gas flow will be in the same direction thereby causing the pistons 74 , 76 to move in the same direction. In this case the pistons will move in the opposite direction to the direction of their motion in the previous cycle. The movement of the pistons again causes the piston rods and the connecting member 80 to move in the same lateral direction as the direction of the gas flow. The movement of the connecting member 80 causes the transmission chain 120 to move. This drives the sprockets 116 and 126 and the flywheel 64 . Energy from the turning of the flywheel can be transferred to the generator 124 . [0060] When the pistons 74 , 76 have reached their maximum travel, a sensor at the front of the cylinder 56 will cause the valves 50 , 52 to close. This cycle continues continuously to cause continuous reciprocation of the pistons. [0061] In an alternate embodiment, the pressure-activated actuator can be a rotary actuator. Other pressure activated actuators known to a person skilled in the art can be used for the purposes of the present invention. [0062] In an alternate embodiment where several pressurized vessels are used, the time for maximum thermal transfer among the vessels to occur can be significantly minimized to the point that this occurs almost instantaneously. [0063] While various embodiments and particular applications of this invention have been shown and described, it is apparent to those skilled in the art that many other modifications and applications of this invention are possible without departing from the inventive concepts herein. It is, therefore, to be understood that, within the scope of the appended claims, this invention may be practiced otherwise than as specifically described, and the invention is not to be restricted except by the scope of the claims.	An apparatus and method for converting a differential in thermal energy between a first thermal source having a thermal conducting fluid and a second thermal source having a thermal conducting fluid is provided. The apparatus emplys a first vessel and a second vessel. Each of the vessels contain a gas under pressure The vessels contain heat exchanging coils that are connected to the thermal sources by fluid lines. A plurality of cooperating valves regulate the flow of the thermal conducting fluid from the first and second thermal sources to the first and second vessels. The valves alternate between first and second operating positions. In the first position, the valves permit a flow of thermal conducting fluid from the first thermal source to the first vessel and from the second thermal source to the second vessel and prevent a flow of thermal conducting fluid from the first thermal source to the second vessel and from the second thermal source to the first vessel. In the second position, the valves permit a flow of thermal conducting fluid from the first thermal source to the second vessel and from the second thermal source to the first vessel and prevent a flow of thermal energy from the first thermal source to the first vessel and from the second thermal source to the second vessel. A pressure driven actuator in fluid communication with the first and second vessels is driven into reciprocating motion between a first position and a second position by alternating positive pressure and negative pressure from the first and second vessels.	5
RELATED APPLICATIONS This application is a Continuation of PCT application Ser. No. PCT/EP03/02811 filed on Mar. 19, 2003 (which was published in German under PCT Article 21(2) as International Publication No. WO 03/105033) which claims priority to German Application No. DE 102 25 711.6, filed on Jun. 10, 2002, both of which are incorporated herein by reference in their entirety. BACKGROUND PRIOR ART The purchaser uses the systems offered to carry out transactions in electronic networks, the internet or mobile phone, only on a very restricted basis. Although there is a multitude of existing payment systems on the internet, they are clearly not used to an adequate extent. All systems operate with already existing and specified procedures for use of a means of payment. The systems prescribe how the customer must pay. Examples are: 1. credit card; 2. virtual wallet; 3. intermediary or cash collector (e.g. Firstgate); 4. dialler software (e.g. 0190 numbers); 5. linked through hardware (e.g. Paybox); 6. account systems; and 7. electronic cash/cheque. Payment by credit card is widespread. Here it is to some extent impossible for the customer to transmit his credit card details unencrypted. The disclosure of such data is not in the interest of the customer, and also not in the interest of the credit card companies. An especially high level of misuse is observed in connection with payments by credit card over the internet. The virtual wallet involves a simple, non-configurable system which is implemented by a main program on a server. Patent specification EP 0 917 120 A2 describes such a system comprised of several distributed parts of a wallet. With the aid of the wallet, a purchase may be made that is anonymous as far as the seller is concerned. Due to the distribution of the parts, data remains on site. Dialler software undertakes the function of the virtual wallet. Payments via this system are not at all transparent for the customer. He is completely reliant on the information supplied by the seller. Hardware-linked systems such as e.g. from Paybox are based on fixed procedures and can be implemented only on certain hardware. There are also account systems for settling reciprocal claims between dealer and purchaser through fixed procedures. Laid-open patent application DE 100 35 581 describes a two-account system. The purchaser fills up an account and processes the payment through this account by means of a mobile phone and the internet. This involves use of the security features of the mobile phone. SUMMARY OF THE INVENTION Electronic cash can as yet be generated and used only in accordance with software specifications. At present there are no means of generating electronic cash to match the needs of the customer for use as a means of payment as in this invention. The problem now is to provide an electronic means of payment which the purchaser can equip with his own security features. The purchaser or user of the means of payment should be able to determine for themselves the security features of the means of payment, procedures of payment transactions, parties involved in the payment transactions, terms and conditions of business, etc. In addition the system must be easy to use. The invention relates to a payment system for cashless payment in electronic networks, in particular the internet and mobile phone networks. The payment system allows a purchaser to use a means of payment personally formulated by him and provided with individual security features. The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings: FIG. 1 is a diagram illustrating theist process that covers the generation of the means of payment according to the present invention; FIG. 2 is a diagram illustrating a 2nd process showing the use of the means of payment according to the present invention; and FIG. 3 is a diagram illustrating the generation and use of the means of payment over unsecured networks (internet) according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method is comprised of two processes, separable from one another, which are harmonized with one another. The 1st process covers the generation of the means of payment ( FIG. 1 ), the 2nd process provides for the use of the means of payment ( FIG. 2 ). The method is operated over unsecured networks with the aid of electronic equipment ( FIG. 3 ). Process 1/Generation of the Means of Payment The customer applies to a bank or similar financial institution (e.g. also a mail order company) for his electronic means of payment (step 1 ). This is effected by means of a suitable secure connection over open networks or in person. After the personal data of the customer have been checked (step 2 ) and confirmed (step 3 ), the customer requests an electronic means of payment (step 4 ). Once the creditworthiness of the customer has been established (step 5 ) and the result communicated to the customer (step 6 ), the customer is able to specify his security features (step 7 ). Alongside those of the bank, the customer can set his individual security features and characterize the course of the payment transactions. The customer thus has the possibility of specifying: the maximum amount of payment; the validity of the means of payment (limited by time, specific transactions or business sectors, categories of goods, particular persons, etc.); the course of the payment transaction; necessary security questions/actions before the transaction; restriction of usability of the means of payment to certain media; possible multiple use of the means of payment; his own passwords to release the means of payment; release only by his SmartCard; and signing with the signature of the customer. After these individual security features have been verified by the bank (step 8 ), this data (data relating to the transaction process in readable form) is packaged into an electronic means of payment. At the same time the means of payment may be given a reference to a virtual and anonymous account to be set up by the bank or by another control system, or to the specific account details of the customer. By setting up an anonymous account it is possible for all subsequent payments by this means of payment to be made anonymously, since the subsequent seller is unable to obtain any personal data. In this case, however, the customer must make a payment into the virtual account or else receive from the bank an agreed credit framework (similar to a credit card). If this payment is made in cash, e.g. at a machine, then the customer is also anonymous to the bank. Finally this electronic means of payment is signed by the bank and transmitted to the customer (step 9 ). Transmission may take place by e-mail, data storage medium (floppy disc), infrared (wireless) connection between two electronic devices, etc. The signature enables a subsequent seller to verify the validity and the usability of the means of payment for a specific transaction. Process 2/Use of the Means of Payment The customer now has an electronic means of payment on his medium (hard disc of his computer, mobile phone, organizer or other electronic device). The means of payment is assigned a program which makes it possible to use the means of payment. If it is intended that this means of payment will be used several times by the customer, then this program requires additional functions to administer, e.g. the residual amount, recipients of payment, etc. The program may be available e.g. in the form of a so-called browser plug-in or as an independent application or as part of the means of payment. The inputs required before a payment (amount details, recipient of payment, invoice number) are then facilitated by this program. To enhance security, the means of payment may be signed and/or encoded by the customer. Open connections may also be encrypted, and the program is able to access a device-side security mechanism such as a SmartCard device, an SIM card in the mobile phone or a stored code. After the seller has transmitted his price offer for the selected goods (steps 11 and 12 ), the means of payment is transmitted to the seller (step 13 ). The seller requires a program which accepts the means of payment and verifies the security features provided (step 14 ). The program decodes the received means of payment, if encrypted, and is able to carry out the following further tasks: check the signature of the bank; check the validity of the means of payment; check the amount entered; check the cover; establish the usability of the means of payment for this transaction; and implement the payment procedure determined by the customer. The program determines the validity and cover of the means of payment by dialling or accessing the computer of the checking authority named in the means of payment. For this purpose the means of payment is transmitted to the checking computer (step 15 ), which confirms the cover and if necessary the usability of the means of payment for this transaction. In addition to the confirmation, the other information is transmitted to the seller (step 16 ). This is evaluated by the seller (step 17 ), who then decides whether or not to supply the goods or services under the conditions stated in the means of payment (terms and conditions of the customer) (step 18 ). The financial transaction may take place at the same time as delivery of the goods or only after release of the means of payment (step 19 ) by the customer. This avoids payment without an actual delivery of the goods, since as a rule the customer will instigate payment only following receipt of the goods. After optional release by the customer, the amount is transmitted to the seller. Embodiments Payment for Services Over the Internet (Micro-Payment) The customer dials in to the bank computer of his bank over a secure connection (SSL). There he requests the issuing of an anonymous, electronic means of payment for multiple use. For this he or she specifies the following security features: maximum value of the means of payment; period of validity of the means of payment; specification of the products to be paid for by the means of payment (e.g. purchasable information sheets from establishments); specification that use is possible only from his own PC (personal computer); and signature of customer necessary before any payment. These security features are now checked by the bank computer (e.g. maximum amount and period of validity). These security features are packaged into the electronic means of payment in readable form, together with bank-specific details (reference to the virtual account to be set up, bank sort code, access data for the bank computer). After transfer of the desired amount from the giro account of the customer, the means of payment is sent to the customer. The customer also receives the necessary code information, for subsequent signing of payment instructions. The customer now selects the service, obtains a price quotation from the seller, and must specify his mode of payment. After selecting the mode of payment by electronic means of payment, a suitable browser plug-in is started. By means of the plug-in, the customer confirms the amount and the recipient. The means of payment with this payment information is then signed, and transmitted to the internet server of the seller. The seller's program determines from the means of payment the access data to the bank computer, where it checks that the means of payment is covered. The bank computer is able to make this check on the basis of the readable information regarding the virtual account, and the customer signature. After receiving positive confirmation from the bank computer, the seller releases access to the desired information. At the same time, by transmitting his bank account details to the bank computer, the seller activates the corresponding transmission from the virtual account to the account of the seller. The virtual account is reduced by the corresponding amount. The same electronic means of payment may be used repeatedly in the same manner until the virtual account of the customer is exhausted. Benefits The main benefit of this novel solution is that the customer or purchaser may themselves determine the security features of the means of payment, and at the same time expand the functions of the means of payment. The customer can define transaction procedures which restrict the validity of the means of payment, thereby matching the security requirement to the ideas of the customer. So for example the customer may request a means of payment for his children which can not be used for example to pay for cigarettes and for literature liable to corrupt the young. The hardware cost of this solution is very low, and is limited in the simplified version to a computer authority on the part of the bank or checking system. For the expanded version, the customer needs to have a card reader. The need for the customer and the seller to have a PC may be regarded as given, since no excessive demands are made on the PCs concerned. Nor does it matter what operating system is used, since the very simple procedures can be run on all operating systems. The solution presented is not limited to certain media or hardware systems. This means of payment may be used in all data transmission systems (internet, mobile phone networks). The facilities on the part of the seller also include an internet connection, so that the connection to the checking authority can be made. The system presented is very easy to use for all concerned. The necessary steps are prescribed by the system and may be understood by average PC users. On the part of the purchaser, no software needs to be installed for the simplified version. In the expanded version, a program is installed to support the administration of means of payment. The program on the seller's side implements the processing of simple procedures, which can be dealt with by an average PC user. With this system it is possible to define means of payment which the customer may define for different purposes, but without having to learn the processes afresh during definition or implementation. For example the customer may define means of payment for a friend, which this person alone may use in a particular business or sector (gift voucher). Equally he may define a means of payment with a high maximum value, e.g. to purchase a car. As a third means of payment he may define a means of payment for multiple use for payments over the internet (small amounts). These means of payment will differ mainly in the individually defined security features, which also correspond to the security requirements of the customer. Where the means of payment have a high value, the customer will be more likely to take a high administrative cost into account. In the micro-payment segment, on the other hand, he will aim for the simplest possible use. The processes involved in creation and use are the same for all means of payment. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.	Electronic means of payment require specific procedures concerning the use thereof as well as set security features. Disclosed is a means of payment allowing the user to add individual security features, comprising the use of specific devices that are available to the user, the purchasing procedure, and additional general conditions pertaining to purchasing goods and services. The electronic means of payment can combine existing payment systems by making the payment systems selectable and allowing individual security features to be adjusted. The popular credit card can become far more secure when purchasing goods and services by combining the credit card with devices providing increased security, for a mobile phone, and adequate general conditions. The user of the means of payment can make payments in an individual manner according to the individual merchandise or service that he/she would like to purchase.	6
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a Continuation-in-Part of copending application Ser. No. 11/397,631 filed on Apr. 5, 2006; which is a Continuation-in-Part of application Ser. No. 10/111,900 filed on Sep. 25, 2002; which is the 35 U.S.C. 371 national stage of international application PCT/FR02/00218 filed on Jan. 18, 2002, which claimed priority of French application No.: 01 00771 filed on Jan. 19, 2001. The entire contents of each of the above-identified applications are hereby incorporated b reference. FIELD OF THE INVENTION [0002] The present invention relates to an expert system of biological analysis. [0003] In the field of biological analysis, there are already methods of determining the biological profile of a person from a set of measurements of characteristic physiological parameters. Starting from these biological profiles and data relating to the person concerned such as his age, his sex, his physical condition, the practitioner can then produce a set of conclusions or outputs leading to a diagnosis. A biological profile is comprised in practice of a set of specific profiles, such as a protein profile or lymphocyte typing. [0004] The increase in the number of parameters involved in the determination of a biological profile makes it more and more difficult to establish consistent conclusions or outputs. In order to satisfy the expectations of practitioners who prescribe biological analyses, expert systems of biological analysis have been developed. These expert systems procure for users the processing of a set of items corresponding to biological measurements data and to personal data, and provide conclusions which can be used directly by the prescribing practitioner. [0005] The methods of processing biological data that are used in these expert systems require a set of rules each applied to a determined combination of items among a global set of items corresponding to a set of measurements, examinations, dosages carried out on a patient or personal data. These rules lead to a set of conclusions which are drafted beforehand by one or more expert practitioners. [0006] It has been shown in practice that the number of possible theoretical conclusions in an expert system of biological analysis, intended to integrate as complete as possible a biological profile in the current state of the techniques available in biological analysis, is so high that the feasibility of such an expert system and its implementation on conventional data-processing equipment other than large-capacity calculation and storage machines could be implicated. BACKGROUND OF THE INVENTION [0007] Buchanon et al. (WO 00/42487) disclose a computer-implemented interactive expert system and method of using it for real time decision support in the medical field. The expert system disclosed in Buchanon et al. contains rules that can be created and modified. Pertinent subsets of rules can be selected to reduce response times by limiting the number of conclusions. However, selecting subsets of rules in order to limit the number of conclusions, may on the one hand be very time wasting and on the second affect the accuracy and rigour of the conclusions supplied to the user SUMMARY OF THE INVENTION [0008] The aim of the present invention is to propose an expert system of processing biological analysis data which on the one hand resolves effectively the question of the volume of data to be processed and consequently render such an expert system realisable, and which on the other hand procures for the practitioner using it a better relevance of the conclusions for interpretation of the analysis results. [0009] This aim is achieved with an expert system of biological analysis, comprising: a collecting engine to collect and represent, in the form of a set of groups of items, data resulting from biological measurements carried out on a human or animal subject and defining a biological profile, and personal data relating to the said human or animal subject, a set of several groups of pre-established rules; an inference engine to issue a set of conclusions by applying at least one group of the said set of groups of rules to: at least one group of items selected from the said set of groups of items; and/or at least one former set of conclusions issued by said inference engine, wherein it also comprises a gathering engine to minimize the number of conclusions in the said set of conclusions issued by the said inference engine. [0015] Such gathering engine accomplishing gathering operations have the effect of making possible the implementation of an expert system of biological analysis on a personal office-based or portable data-processing apparatus, without affecting the accuracy and rigour of the conclusions supplied to the user. [0016] It is to be noted that in the present invention gathering operations relates to gathering the number of conclusions in a set of conclusions and not to the fusion of chained rules as taught in the pending U.S. Pat. No. 5,442,792 which discloses a compiling method for an expert system. [0017] It is also to be noted that an “engine” can be a computer program, one or more software run by a computer or made of computer executable instructions run by a computer, a processor or the like. Many structures of “engine” are well known in the expert systems known in the art, such as those described in the U.S. Pat. No. 5,263,126. [0018] It is still to be noted that a “conclusion” means the output of a rule executed by an engine and more particularly by an inference engine. A “conclusion” can, for example, be a numerical value, a word, a sentence or the like, and is well known in the art. [0019] Another aim of the method of data processing according to the invention is to permit the realisation of an expert system of biological analysis which integrates genetic profile data, knowledge of which is henceforth regarded as essential for the diagnosis and treatment of an increasing number of affections and pathologies. [0020] This aim is achieved by an expert system comprising a genetic data collecting engine collecting data relating to the genetic profile of the said human or animal subject in the form of genetic items, said genetic data collecting engine also comprising a set of rules for the interpretation of the said genetic data. [0021] The genetic data collecting engine can also comprise a processing of genetic data relating to this patient in the form of a set of genetic items associated with a set of genes studied in this patient, this processing comprising the application of rules of genetic interpretation applied at the same time to biological items and to genetic items. [0022] With this expert system combining interpretation of a biological profile and interpretation of a genetic profile, it becomes possible to propose more accurate and more relevant conclusions due to the taking into account of affections linked with the genes. [0023] It is to be noted that document WO 01/16860 discloses artificial intelligence system for a genetic analysis, which does not involve a gathering operation of a set of conclusions that have resulted from a group of rules, as proposed by the method according to the invention. [0024] Said collecting engine, said set of several groups of pre-established rules, said inference engine and said gathering engine can also be integrated into an automated system including operations determining a biological and a genetic profile of a patient. [0025] The expert system according to the present invention can further comprise a coupled knowledge base, so that it can reach all the information present in the knowledge base. Thus, with the expert system according to the present invention the interpretation of a biological profile and interpretation of a genetic profile, it becomes possible to propose more accurate and more relevant conclusions due to the taking into account of information present I the coupled knowledge base. [0026] The biological profile taken into account in the expert system according to the present invention also includes a protein profile. [0027] The biological profile taken into account in the expert system according to the present invention also includes a lymphocyte typing. [0028] According to another aspect of the invention it is proposed an expert system of biological analysis, comprising computer executable instructions defining: a collecting engine to collect and represent, in the form of a set of groups of items, data resulting from biological measurements carried out on a human or animal subject and defining a biological profile, and personal data relating to the said human or animal subject, a set of several groups of pre-established rules; an inference engine to issue a set of conclusions by applying at least one group of the said set of groups of rules to: at least one group of items selected from the said set of groups of items; and/or at least one former set of conclusions issued by said inference engine, wherein it also comprises a gathering engine to minimize the number of conclusions in the said set of conclusions issued by the said inference engine. [0034] According to another aspect of the invention it is proposed a method for processing biological analysis data, comprising: collecting and representing, in the form of a set of groups of items, data resulting from biological measurements carried out on a human or animal subject and defining a biological profile, and personal data relating to the said human or animal subject, issuing a set of conclusions by applying at least one group of a set of several groups of pre-established rules to: at least one group of items selected from the said set of groups of items; and/or at least one former set of conclusions issued by said inference engine, wherein it also comprises gathering at least two conclusions from the said set of conclusions to minimize the number of conclusions in the said set of conclusions. BRIEF DESCRIPTION OF THE DRAWINGS [0039] Other advantages and characteristics of the invention will appear upon examination of the detailed description of an embodiment, which is no way limitative, and of the attached drawings in which: [0040] FIG. 1 is a functional diagram of an expert system of biological analysis according to the invention, [0041] FIG. 2A illustrates an example of internal structure of the engine of an expert system according to the invention, relating more particularly to rules of the inflammatory reaction, and [0042] FIG. 2B illustrates an example of internal structure of the engine of an expert system according to the invention, relating more particularly to rules of interpretation of immunoglobulin. DETAILED DESCRIPTION OF THE INVENTION [0043] An expert system according to the invention of biological analysis according to the invention can in practice be implemented within a computer such as an office computer or a portable computer, and accessed locally or remotely. Its internal architecture, which can conform to current standards applying to expert systems, includes, with reference to FIG. 1 , a module for collecting data determining profiles, respectively biological (protein in particular) and genetic profiles, of a patient, a module for collecting personal information specific to the patient, rules of interpretation applied to a processing of the biological profile realised with a genetic interpretation, and an editing of conclusions or outputs that can be used by a practitioner user. [0044] The set of rules contained in this expert system according to the invention is organised into groups of rules each group corresponding to a group of specific analysis among several groups of analysis. For example, one may consider the group of rules of the inflammatory reaction or the group of rules interpreting immunoglobulins. [0045] An embodiment of an expert system according to the invention will now be described, with reference to FIGS. 2A and 2B , being limited, for reasons of fullness of the description and clarity, only to the protein profile of a patient, it being understood that other specific biological profiles could be processed in an equivalent manner within the scope of the present invention. [0046] In this expert system, a protein profile comprises optional items such as Item 43=ROP or Item 45=C4 and a set of obligatory items such as the following items: [0000] Item 2 = Age Item 3 = Sex Item 35 = ORO 35.1 = Normal 35.2 = Increased 35.3 = Much increased 35.4 = Reduced Item 36 = HAPTO 36.1 = Normal 36.2 = Increased 36.3 = Much increased 36.4 = Reduced 36.5 = Much reduced Item 37 = CRP 37.1 = Normal < 33% 37.2 = Normal increased 37.3 = Increased 37.4 = Much increased 37.5 = Very much increased . . . Item 39 = TRF 39.1 = Normal 39.2 = Increased (obligatorily > 119, not below) 39.3 = Reduced Item 40 = ALB 40.1 = Normal or increased (>89%) 40.2 = Reduced (<89%) Item 41 = TRF/ALB 41.1 = Normal 41.2 = Increased Item 42 = PAB 42.1 = Normal or increased (>84%) 42.2 = Reduced (<84%) Item 44 = Electrophoresis of the proteins effected NO IgM IgG IgA Monoclonal peak not M, not G, not A Double monoclonal peak Absence of monoclonal protein [0047] The expert system according to the invention includes rules of the inflammatory reaction such as the following rules: RINF1=35.1+36.1+37.1=CINF1 RINF2=35.1+36.1+37.2=CINF2 . . . RINF100=35.4+36.5+37.5=CINF100 The conclusions associated with these rules of the inflammatory reaction are for example written up in the following way: CINF1=No inflammatory reaction as the proteins of the inflammation (CRP, Alpha-1-glycoprotein or orosomucoid, haptoglobin) are normal. CINF2=The proteins of the inflammatory reaction are all in normal values. However, the level of CRP, although normal, may suggest the presence of microinflammations (to be taken into consideration in the assessment of the cardiovascular risk after formal elimination of any other potentially phlogogenic spot). CINF100=The results lean towards an inflammatory process based solely on the strong increase in the CRP. This may be the start of an inflammatory process since the CRP, a protein of acute inflammation, increases more quickly than the other proteins of the inflammation. Such an induction leans towards an infectious and/or inflammatory spot that is at the present time recent and very active, kept in an active state or in re-induction phase. The low level of haptoglobin is favourable for a hemolysis. Any haptoglobin result below 50% can be considered pathological. It may thus be of benefit to seek the cause of this hemolysis. Here, the reduced level of alpha-1-glycoprotein need not suggest a medicament treatment in the first place, but rather a protein leak, or a hepatocytic insufficiency. [0055] Some of the conclusions CINF1 to CINF100 are impossible. There are 60 different conclusions left. Although there are actually only 60 different conclusions, this would lead to far too great a number of rules and conclusions. It is thus proposed to gather these 60 conclusions to obtain 6 new conclusions as represented in FIG. 2A . This gathering operation is made by grouping the conclusions by meaning. The new conclusions are built in the following way: RINF301=CINF1 or CINF2 or CINF3 or CINF6 or . . . or CINF83=CINF301 [0056] The 6 new conclusions are: 1) CINF301: no, or very slight, inflammatory reaction 2) CINF302: inflammatory reaction based solely on the increase in CRP 3) CINF303: inflammatory reaction with increase in only one protein of the chronic reaction 4) CINF304: clear inflammatory reaction with normal CRP 5) CINF305: clear inflammatory reaction with increased CRP 6) CINF306: reduction in the proteins of the chronic inflammation If 6 conclusions CINF301 to CINF306 are considered, linked with items 39 (TRF), 40 (ALB), 41 (TRF/ALB), 42 (PAB), 6×3×2×2×2, i.e. 144 gathering rules must be provided. The 144 possible different rules include: RINF307=CINF301+39.1+40.1+41.1+42.1=CINF307 . . . RINF450=CINF306+39.3+40.2+41.2+42.2=CINF450 144 different conclusions are obtained. A gathering step is then performed to link the 144 conclusions obtained. The conclusions CINF307 to CINF450 are linked together to obtain a reduced number of conclusions. [0066] The interpretation of the Ig (immunoglobulins) in the protein profile will now be considered. The items concerned are 31 (IgM), 32 (IgG) and 33 (IgA). The interpretation of the inflammatory conclusions CINF1 to CINF100 is different. There be a different gathering of the inflammatory conclusions CINF1 to CINF100 to obtain 5 new conclusions. These 5 new conclusions will be then linked to the items 31 to 33. [0067] The interpretation of the Ig (immunoglobulins) in the protein profile is different depending on whether there is or not a monoclonal protein. Now, the presence of a monoclonal protein is not visible in the protein profile but in another analysis which is electrophoresis of the proteins. When a monoclonal protein is found, the interpretation stops there, and this finding is not linked with an inflammatory reaction. Thus, the interpretation of the Ig starts with the processing of item 44 “Electrophoresis of the proteins”. [0068] The reply may be: 44.1: no (1 st finding), 44.2: yes with presence of a monoclonal protein (new 1 st finding), 44.3: yes with absence of monoclonal protein (new 1 st finding), The first finding can be established in the following way: RIG1=44.2+12.1=CIG1 . . . RIG13=17.2=CIG13 CIG1=The electrophoresis and the immunoelectrophoresis revealed a monoclonal IgM. Given the patient's age, one must think first of a sub-acute or chronic severe infection or viral or bacterial origin. This suggests an associated immunodeficiency. CIG13=The values of the Ig reflect all of the defences acquired during life as a function of encounters with the different pathogens. At adult age, in a healthy person, this level does not vary much. It is thus perfectly possible that a level outside the normal values has no pathological connotation, but be a perfectly physiological level for the patient. What is interesting is the assessment of the variation over two samples several months apart. Not having any prior history for this patient, the different etiologies proposed enjoy only indicative status, as the interpretation must be carried out above all in relation to the clinical context. [0077] Any individual can present Ig levels outside the standard values without this being pathological. What is pathological is the variation in this level of Ig over two taking, hence the processing of item 7 “previous histories”. If the reply is no, this means a 2 nd finding of a general order before the actual processing of the Ig. [0000] Items 31, 32, 33 must then be linked with the inflammatory reaction. As précised above, we create 5 new inflammatory conclusions which summarize inflammatory reactions by meaning in the immunoglobulin interpretation context. These conclusions are: CIG101: no inflammatory reaction CIG102: slight inflammatory reaction CIG103: inflammatory reaction due solely to CRP CIG104: inflammatory reaction present (1, 2 or 3 proteins) CIG105: reduction of the proteins of the inflammatory reaction. The 3 rd finding will thus be chosen from among the following rules: RIG101=CINF1 or CINF18 or . . . or CINF78=CIG101 [0084] The new inflammatory conclusions CIG101 to CIG105 are obtained by a different gathering of the conclusions CINF to CINF100. [0085] We now combine items such as I31×I32×I33 with the new 5 inflammatory conclusions (CIG101 to CIG105) and we obtain: 5×3×5×5=375 new rules. [0086] The 375 rules for the 3 rd finding are then established, such as by way of example: RIG106=CIG101+31.1+32.1+33.1=CIG106 . . . RIG480=CIG105+31.5+32.3+33.5=CIG480 . . . [0091] By combining items I31 to I33 with the new 5 inflammatory conclusions we obtain 375 conclusions CIG106 to CIG480 [0092] Complementary rules as a function of age are added to take account of the situations where each time there will be an inflammatory reaction (CIG104) without any increase in the Ig, or with a reduction in the IgM. In order to create these complementary rules, a gathering of certain of the CIGxxx conclusions mentioned above is carried out in order to end up with 5 conclusions CIG1200, CIG1201, CIG1202, CIG1203, CIG1204 which are used in the establishment of these complementary rules. RIG1200=CIG152 or CIG153 or . . . or CIG180=CIG1200 RIG1205=CIG1200+750.2=CIG1205 [0095] Moreover, many conclusions CIG106 to CIG480 have a similar text, only some words are different depending on the rule input. For example we have these 2 rules: RIG167=CIG102+31.4+32.2+33.3+MOL.746 (item for drug intake Corticoid therapy)=CIG167 RIG168=CIG102+31.4+32.2+33.3+MOL.753 (item for drug intake Methotrexate)=CIG168 And the corresponding conclusions are: CIG167=“In this patient case, use of corticoid therapy may explain such immunoglobulin values.” CIG168=“In this patient case, use of methotrexat may explain such immunoglobulin values.” [0100] In order to avoid writing 2 rules and 2 conclusions we create only one rule and conclusion use the principle of “a magic hole”: RIG167N=CIG102+31.4+32.2+33.3+(MOL.746 or MOL.753)=CIG167N [0102] The rule combines the conclusion CIG102, items 31, 32, 33 and one of the drugs among MOL.746 and MOL.753. [0103] We then create the following conclusion: CIG167N=“In this patient case, use of [[MOL]] may explain such immunoglobulin values.” [0105] When the algorithm will find the specific characters “[[MOL]]” (which we named “the magic hole”), it will replace it by a human readable text of the item which activates that rule. If the item MOL.746 is selected in the patient profile, the rule will be activated and the content of the conclusion will be replaced by “In this patient case, use of corticoid therapy may explain such immunoglobulin values.” [0106] An embodiment of the method of processing data according to the invention will now be described, for a combined interpretation of the genetic profile and cardiovascular risk. [0107] Firstly, a non-exhaustive list of genes that can be interpreted within the scope of the expert system of biological analysis according to the invention is provided in table I below. For each gene, a + symbol in a column indicates that this gene plays a part in the characteristic corresponding to this column, and conversely a − symbol in another column indicates that the same gene does not play a part in the characteristic corresponding to this other column. Thus, by way of example, the gene CYP1A1 plays a part in the case of smoker and as regards nutrigenetics, but not as regards pharmacogenetics, immunogenetics and for oxidative stress. Thus, each + symbol in this table corresponds to links and rules which must be written and integrated into the expert system. [0108] There follow, by way of non-limitative example, extracts of biological interpretation supplied by an expert system according to the invention, regarding cardiovascular risk: [0000] “in the light of the biological results, there is no atherogenic risk. The other risk factors must therefore be explored, as nearly 20% of patients who have cardiovascular problems present a normal or sub-normal biology.” [ . . . ] “Hyperhomocystinemia caused by congenital deficiency of the enzymes involved in its biosynthesis is much more rare. For example, cystathionine-beta-synthase deficiency is estimated at 1/20000 subjects who, in addition to cardiovascular risk, also have mental backwardness, and a dislocation of the crystalline lens, osseous deformations. On the other hand, 5-10 methylinetetrahydrofolate reductase deficiency is more frequent, being estimated at 5% of the general population, and is the major cause of genetic predisposition to moderate hyperhomocystinemia. These patients often present cardiovascular disorders in the first years of life [ . . . ]” This constitutes an indication for conducting genetic tests in order to know whether the increase in homocysteine is genetic in origin or not. “Although the E2 allele seems to play a part in type III hyperlipoproteinemias, the E4 allele is also more involved in cardiovascular diseases. The E2/E4 genotype, although infrequent, thus substantially increases the risks of cardiovascular problems. Generally speaking, the average cholesterolemia of E4/E3 subjects is greater than that of E3/E3 subjects, which is itself greater than that of E3/E2 subjects. In the same way, the average concentration of LDL cholesterol in E4/E3 subjects is greater than that of E3/E3 subjects, which is itself greater than that of E2/E2 subjects. On the other hand, the triglycerides are significantly higher in E2/E2; E3/E2; E4/E2 subjects than in E3/E3; E4/E3 subjects.” [0109] This finding reflects a direct relationship between interpretation of a genetic profile and interpretation of a biological profile (cholesterol, triglycerides). [0110] There is presented below an example of a finding reflecting a direct relationship between genetics and diet: [0000] “Subjects carrying the E4 allele are more sensitive to hypolipemic and hypocholesterolemic diets. In the same subjects, the return to a diet rich in fats, in particular in saturated fatty acids, leads to a greater increase in plasmatic cholesterol.” [0111] The expert system according to the invention can also take account, in the conclusions supplied to the user, of a direct relationship between the interpretation of the genetic profile and data relating to the medicament treatment that are obtained from personal information specific to the patient, as illustrated by the finding presented below: [0000] “Subjects carrying the E2 allele and affected by hyperlipoproteinemia of lib type respond well to treatment by gemfibrozil and by statins (simvastatin and lovastatin). Among subjects affected by hyperlipoproteinemia of lia type, carriers of the E2 or E3 allele respond well to treatment by statins. Subjects carrying the E4 allele would on the other hand respond less well to hypolipidemic medicamentous treatments, with the exception, perhaps, of probucol.” [0112] The invention is, of course, not limited to the examples which have just been described and numerous modifications can be made to these examples without exceeding the scope of the invention. In particular, provision can be made for complete automation of the operations for determining the biological profile and the genetic profile of a patient, and the combined treatment of these profiles. Moreover, it will easily be understood that an expert system of biological analysis according to the invention can also be coupled with databases and knowledge bases. In addition, within the framework of the present invention, the biological profile not only includes several families of determinations and biological analysis which are henceforth well established such as protein profiling or lymphocyte typing, but also other profiles in the process of being developed or which will be proposed in the future. In the same way, the expert system according to the invention is intended to take account of increasingly complex genetic profiles as scientific and technological advances occur in this field. [0000] TABLE I Predisposition to Genes disease Pharmacogenetic Immunogenetic Smoker Stress O. Nutrigenetic Phase I of bio- transformation CYP1A1 + − − + − + CYP1A2 + + − + − − CYP2A6 + + − + − − CYP3A4 + + − − − + CYP2B6 + + − − − + CYP1B1 + + − − − + CYP2D6 + + − − − − CYP2E1 + − − − − + CYP2C19 + + − − − − CYP2C9 − + − − − − MEH + − − + − − ALDH + − − + − − ADH2 + − − + − − Phase II of bio- transformation GSTM1 + + + + + + GSTM3 + − − − + + GSTT1 + − − + + + GSTP1 + + − − + + NAT2 + + + + − + NAT1 + + + + − + Trigger genes Osteoporosis Vit D3 + − − − − − Col1A1 + − − − − − ER + − − − − − CTR + − − − − − AIDS CCR5 + − − − − − SDF1 + − − − − − CCR2 + − − − − − CXCR4 + − − − − − Breast cancer BRCA1 + − − − − − BRCA2 + − − − − − Prostate cancer AR + − − − − − Hereditary trombophilia Factor V + − − − − − Hemochromatosis HFE + − − − − − Bronchial and allergic asthma CC16 + − − − − − AAT-locus + − − + − − HNMT + − − + − − PAFAH + − − + − − AACT + − − + − − Primary Hypercholesteremia LDLR + − − − − − APOB + − − − − − Cardiovascular risk MTHFR + − − − − − ACE + − − − − − Efflux genes MDR1 − + − − − − MDR3 − + − − − − LRP − + − − − − MRP1 − + − − − − Other metabolizing genes NQO1 + − − − + − Cytokine genes IL-1a + − + − − − IL-1b + − + − − − ILRN + − + − − − IL-2 + − + − − − IL-4 + − + − − − IL-6 + − + − − − IL-9 + − + − − −−	An expert system of biological analysis includes a collecting engine to collect and represent data resulting from biological measurements carried out on a human or animal subject and defining a biological profile, and personal data relating to the human or animal subject.	6
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is the U.S. national phase, under 35 U.S.C. 371, of PCT/EP2009/060651, filed Aug. 18, 2009, published as WO 2010/026041 A1 on Mar. 11, 2010, and claiming priority to DE 10 2008 041 847.1, filed Sep. 5, 2008, the disclosures of which are expressly incorporated herein by reference. FIELD OF THE INVENTION [0002] The invention relates to a printing unit of a printing press comprising at least two frame parts, the position of which relative to one another can be changed. Interacting frame parts are placed against each other along a shared joining surface in a first operating position and are moved away from each other in a second operating position. Between the frame parts, that are moved away from each other in the printing unit, an intermediate space is formed. This intermediate space is delimited, in part, by the frame parts. At least one of the frame parts is movable along an adjustment path. BACKGROUND OF THE INVENTION [0003] WO 95/24314 A1 and WO 2005/037 553 A1 each describe a printing unit of a printing press comprising at least two frame parts, the position of which relative to one another can be changed, wherein interacting frame parts are placed against one another in a first operating position, and are moved away from one another in a second operating position, wherein between frame parts that have been moved away from one another, an intermediate space, delimited in part by said frame parts, is formed in the printing unit, wherein at least one printing couple cylinder is mounted in each of the respectively interacting frame parts. [0004] EP 1 790 474 A1 describes a printing press comprising a printing unit with one stationary frame part and at least one frame part that is movable along a linear adjustment path, wherein the stationary frame part has at least one printing couple, wherein at least one inking unit is arranged in the movable frame part, wherein in a first operating position interacting frame parts are placed against one another and in a second operating position said parts are moved away from one another, wherein between frame parts that have been moved away from one another, an intermediate space, delimited in part by said frame parts, is formed, wherein a safety apparatus is provided, which uses a detection device disposed on the movable frame part to detect the presence of an obstacle in the adjustment path of said movable frame part. [0005] EP 0 444 227 A1 describes a printing press comprising a printing unit having at least two frame parts, the position of which relative to one another can be changed, wherein printing couple cylinders are arranged in a stationary frame part, and at least one inking unit is arranged in the at least one movable frame part, wherein in a first operating position, interacting frame parts are placed against one another and in a second operating position said frame parts are moved away from one another, wherein between frame parts that have been moved away from one another, an intermediate space, delimited in part by said frame parts, is formed in the printing unit, wherein mat switches are provided, which prevent the printing couple cylinders from rotating, for example, when a person steps on one of said mat switches while the frame parts are in the operating position in which they are moved away from one another. [0006] DE 102 24 031 B3 describes a device for monitoring a scanning zone of a working apparatus, said device comprising at least one redundant camera system consisting of two cameras and a beam splitter positioned upstream thereof, via which images of the scanning zone can be displayed on both cameras for detecting objects that may pose a safety risk within at least one safety zone, and comprising two computer units, wherein each computer unit is connected to one of the cameras for evaluating the image data acquired there, and wherein the two computer units are coupled to one another for the purpose of mutual verification, and comprising at least one switch output actuated by the computer units, via which output the working apparatus is placed in operation only if no object that may pose a safety risk is found within the safety zone. [0007] DE 10 2004 037 888 A1 describes a printing unit of a web-fed rotary printing press, which comprises two frame sections, mounted so as to be movable in relation to one another, each having at least one printing couple with at least two interacting printing couple cylinders, wherein the printing couple cylinders are mounted with each cylinder end disposed in a bearing unit having at least one actuator, wherein each printing couple cylinder can be radially displaced in its respective bearing unit by means of the actuator, wherein the actuator is embodied as an adjustment means which is actuable via a pressurized medium, such as oil. [0008] DE 200 11 699 U1 describes a printing press with an impression cylinder and at least one printing couple assigned to said cylinder, which printing couple comprises at least two bearings with socket-type supports for the interchangeable installation of tubular printing equipment parts, and an inking unit, wherein the bearing and the inking unit are supported so as to be displaceable with respect to their distance from the impression cylinder along at least one guide rail, and wherein the socket-type supports of the bearing can optionally be loaded with a selection of equipment parts on the basis of the printing technique and/or printing format, wherein the bearing and the inking unit are displaceable between an operational position, a switching position and an off-line position, wherein the bearing and the inking unit are displaceable on the guide rails, embodied as toothed racks, by means of an allocated servo motor, for displacement to the respective operational position, switching position and off-line position. [0009] U.S. Pat. No. 5,025,726 A describes a printing unit of a rotary printing press having two frame sections, one of which is movable in relation to the other, wherein a locking system is provided. [0010] FR 2 648 506 A1 describes a variable-width safety barrier for blocking off a hazardous area. [0011] The documentation of the SICK AG company in D-79183 Waldkirch, Germany, describes safety laser scanners, product number 8010739, and the use thereof, wherein the publication date of said documentation is listed as 1 Apr. 2006. SUMMARY OF THE INVENTION [0012] The problem addressed by the invention is that of devising a printing unit for a printing press, comprising at least two frame parts, the position of which relative to one another can be changed, wherein a hazard posed by at least one moved frame part of said printing unit to a press operator working in the hazardous area of said printing unit is prevented. [0013] The problem is solved according to the invention by a printing unit having at least one sensor that is usable for monitoring the intermediate space between the frame parts. This sensor has a directional characteristic effective along the joining surface or has a sensing zone effective along the joining surface. A field width of a first angular field of the directional characteristic or of the sensing zone, and which width is oriented parallel to the adjustment path of a movable frame part, is smaller than a respective field width of a second or third angular field of the directional characteristic or sensing zone. The field width of the second angular field of the directional characteristic or the sensing zone is oriented in the axial direction of at least one printed couple cylinder that is mounted in the movable frame part. The field width of the third angular field of the directional characteristic or the sensing zone is oriented in the direction of a height of the movable frame part. [0014] The benefits to be achieved by the invention consist particularly in that the printing unit offers a high level of operational safety. In particular, the printing unit has a safety device which helps to prevent a hazard posed by at least one moved frame part of said printing unit to a press operator working in a hazardous area of said printing unit. BRIEF DESCRIPTION OF THE DRAWINGS [0015] Embodiment examples of the invention are illustrated in the drawings and are described in greater detail in what follows. [0016] The drawings show: [0017] FIG. 1 a printing unit comprising two frame parts, the position of which relative to one another can be changed, in a first operating position; [0018] FIG. 2 the printing unit of FIG. 1 , with its frame parts in a second operating position; [0019] FIG. 3 a block diagram; [0020] FIG. 4 variants for monitoring the intermediate space formed between frame parts of the printing unit, and variants of an access control device; [0021] FIG. 5 another variant of the access control device. DESCRIPTION OF THE PREFERRED EMBODIMENT [0022] FIGS. 1 and 2 each illustrate, by way of example, a printing unit 01 , embodied as a tower, particularly as an eight-couple tower, enclosed inside a frame 12 embodied, for example, as a structural framework, for a rotary printing press, which is preferably usable for color newspaper printing, wherein the printing unit 01 is highly compact in configuration, i.e., particularly having a low structural height. Two eight-couple towers of this type may also be placed one on top of the other to form a printing unit 01 embodied as a 16-couple tower. A preferably web-type print substrate 02 , for example, a paper web 02 , to be imprinted in the printing unit 01 is preferably guided substantially vertically through the printing unit 01 . Preferably a plurality of printing couples 03 are arranged preferably on each side of the paper web 02 , wherein each of said printing couples 03 has at least one printing couple cylinder 04 , particularly transfer cylinder 04 , and preferably one forme cylinder 06 , which interacts with the transfer cylinder 04 . Each printing couple 03 is also equipped with a preferably keyless inking unit 07 having multiple rollers, for example, an anilox inking unit 07 having a screen roller, wherein the rollers of the inking unit 07 draw ink from an ink reservoir 09 and form it into a thin ink film, evening out the thickness of said ink film, and transport said film to the respective forme cylinder 06 for the purpose of applying it to at least one printing forme arranged on the forme cylinder 06 . The respective forme cylinder 06 of each of the printing couples 03 has an axial length of between 1,000 mm and 4,000 mm, for example, preferably between 1,200 mm and 2,600 mm, particularly between 1,600 mm and 2,100 mm, and preferably holds a plurality of printing formes, for example, four or six, side by side in its axial direction, wherein the respective subject of each printing forme is assigned to a specific page of the printed product to be produced by the rotary printing press, for example, a newspaper. The axial length of the transfer cylinder 04 is adapted to the respective forme cylinder 06 that interacts with it. The transfer cylinder 04 and the respective forme cylinder 06 can have the same circumference ( FIGS. 1 and 2 ), or the circumferential length of the forme cylinder 06 is about one-half the size of the assigned transfer cylinder 04 . The rotary printing press illustrated by way of example in FIGS. 1 and 2 prints, for example, in an offset printing process, preferably in a dry offset printing process, i.e., in an offset printing process that does not use a dampening agent, therefore the printing couples 03 depicted in FIGS. 1 and 2 do not have dampening units. [0023] In the preferred embodiment, at least one, and particularly each, of the printing couples 03 of the printing unit 01 has a printing forme magazine 08 , wherein each respective printing forme magazine 08 is assigned to the forme cylinder 06 of the respective printing couple 03 . Each printing forme magazine 08 has at least one storage position for storing at least one printing forme, wherein each storage position is preferably embodied in a chute or as a chute, wherein said chute preferably has a transport device, for example, remotely actuable, for supplying at least one new printing forme to the forme cylinder 06 . Each printing forme magazine 08 preferably also has a chute with an also preferably remotely actuable transport device for removing at least one used printing forme from the forme cylinder 06 . [0024] The printing formes are each fastened to the respective forme cylinder 06 by means of a retaining device, for example, a clamping device, preferably remotely actuable, arranged in the respective forme cylinder 06 . The retaining device is embodied as pneumatically actuable, for example, and is arranged in a groove 11 in the respective forme cylinder 06 , wherein said groove 11 extends in the axial direction of the relevant forme cylinder 06 . [0025] The frame 12 of the printing unit 01 consists, for example, of one lower and one upper support, each arranged horizontally, and, for example, two side frames, preferably arranged vertically between these two supports, wherein supports and side frames together form a frame, for example, which holds the printing unit 01 , preferably encompassing it. The lower support can be embodied to act as the preferably substantially rectangular base plate of the printing unit 01 , whereas the upper support forms a cover plate for the printing unit 01 , for example. The printing unit 01 encompassed by said frame 12 has at least two frame parts 13 ; 14 , the position of which relative to one another can be changed, wherein one of said frame parts 13 is preferably embodied as stationary in the shared frame 12 (in FIGS. 1 and 2 , the left frame part 13 , for example), whereas at least one other frame part 14 that interacts with the stationary frame part 13 (in FIGS. 1 and 2 , the right frame part 14 , for example) is arranged in the shared frame 12 so as to be movable, particularly positionable, bidirectionally, for example, parallel to the lower and upper supports, along a preferably linear adjustment path S between two end points that delimit the adjustment path. Because at least one of the interacting frame parts 13 ; 14 , which have a substantially rectangular base surface, is movable, the frame parts 13 ; 14 have two different operating positions, wherein in a first operating position the frame parts 13 ; 14 are placed against one another along a shared joining surface 16 which extends across the height H and width B of the printing unit 01 ( FIGS. 1 , 2 and 4 ), and in a second operating position, the frame parts are moved away from one another ( FIG. 2 ). The second operating position of the movable frame part 14 is indicated by dashed lines in FIG. 2 . The shared joining surface 16 between the interacting frame parts 13 ; 14 is illustrated in FIG. 1 by way of example as two cut-outs. In a first operating position, the frame parts 13 ; 14 , the position of which relative to one another can be changed, are placed directly against one another, with no intermediate space 17 , wherein in this first operating position, the at least one movable frame part 14 can be locked in position, at least at the relevant end point of the adjustment path S, preferably via remote actuation, to prevent it from moving unintentionally. The joining surface 16 between frame parts 13 ; 14 placed against one another, formed in the first operating position, coincides, for example, with a transport plane of the paper web 02 , which is preferably guided vertically through the printing unit 01 . In the second operating position, the interacting frame parts 13 ; 14 , the position of which relative to one another can be changed, are moved away from one another such that their respective sides that face the paper web 02 being guided through the printing unit 01 are opposite one another in parallel. During the changeover from the first operating position to the second operating position, the width of the preferably rectangular-shaped intermediate space 17 present between the interacting frame parts 13 ; 14 can be changed between a minimal value, preferably zero, and a maximum value of 1 m to 2 m, for example. [0026] At least one printing couple cylinder 04 , particularly embodied as transfer cylinder 04 , is mounted in each of the interacting frame parts 13 ; 14 , wherein when the interacting frame parts 13 ; 14 are in the first operating position, the at least one printing couple cylinder 04 , mounted in the frame part 13 which is stationarily positioned in the frame 12 , for example, can be placed against the at least one printing couple cylinder 04 mounted in the other frame part 14 which is movably positioned in the frame 12 , for example, thereby forming a shared print position that imprints the paper web 02 particularly on both sides. In the second operating position, in which the two frame parts 13 ; 14 , the position of which relative to one another can be changed, are moved away from one another, an intermediate space 17 , delimited in part by the frame parts 13 ; 14 , is formed between these two frame parts 13 ; 14 in the printing unit 01 , particularly within the structural frame thereof, wherein said intermediate space 17 is then freely accessible and passable to press operators of the printing unit 01 , at least when the frame part 14 which is movably arranged in the frame 12 has reached the end point at which it is the maximum distance from the joining surface 16 formed with the stationary frame part 13 ( FIG. 2 ). The at least one movable frame part 14 can also be locked in place in its second operating position, particularly at the relevant end point of the adjustment path S, to prevent it from moving unintentionally. In the preferred embodiment, a plurality of printing couples 03 , particularly four, are arranged in each of the interacting frame parts 13 ; 14 . Each of the interacting frame parts 13 ; 14 , particularly movable frame part 14 , has a mass of 30 tons or more, for example. [0027] On one operating side 21 of at least one of the frame parts 13 ; 14 , a height-adjustable operator's platform 22 is arranged, for example, to facilitate access by press operators working on the printing unit 01 to the upper printing couples 03 of the printing unit 01 . The operating side 21 of the respective frame part 13 ; 14 is located on the side thereof that faces away from the transport plane of the paper web 02 being guided through the printing unit 01 . Additionally or alternatively, a height-adjustable operator's platform 22 that can also be lowered into the base plate is also arranged, for example, in the intermediate space 17 which is delimited in part by the interacting frame parts 13 ; 14 . [0028] To allow the movable frame part 14 to be moved, said part is mounted, for example, in a linear bearing and/or is guided in such a bearing as it is being moved. For implementing the movement of the frame parts 13 ; 14 , the position of which relative to one another can be changed, at least one drive unit 23 is provided, which is assigned to at least one of the interacting frame parts 13 ; 14 to change it from one operating position to the other operating position. As was described above, at least one printing couple cylinder 04 is mounted in each of the interacting frame parts 13 ; 14 , wherein at least a second drive unit 24 is provided for implementing a radial movement of the respective printing couple cylinder 04 , wherein the radial movement of the respective printing couple cylinder 04 particularly has an orthogonal component relative to the joining surface 16 of the frame parts 13 ; 14 . The printing couple cylinders 04 arranged in the same frame part 13 ; 14 can be moved radially by the respective second drive unit 24 , all together, or each selected individually. [0029] Each of the drive units 23 ; 24 has, for example, at least one operating cylinder that can be acted on by a pressurized medium, wherein to reduce energy costs, both drive units 23 ; 24 and preferably also a locking system 26 for latching or locking the relevant movable frame parts 13 ; 14 in place in their respective operating positions, i.e., particularly at the respective end points of the relevant adjustment path S, are preferably supplied with power, for example pressurized hydraulic fluid, from a shared energy storage device 27 , particularly from the same hydraulic unit 27 , so that only a single conduit system 19 is required for supplying power to the two drive units 23 ; 24 , and if applicable to the locking system 26 , in the printing unit 01 ( FIG. 3 ). The hydraulic unit 27 has, for example, a compressor or a pump. The supply of power to at least one of the two drive units 23 ; 24 and to the locking system 26 can preferably be remotely actuated, for example, from a preferably electronic control unit 28 , particularly from a control center 28 belonging to the printing unit 01 , wherein the two drive units 23 ; 24 and the locking system 26 can each be actuated individually and independently of one another. The hydraulic unit 27 pressurizes the operating cylinder of the drive units 23 ; 24 with a pressure of, for example, 100 bar to 500 bar. The functional units connected to the same hydraulic unit 27 as the two drive units 23 ; 24 and the locking system 26 are switched to pressureless or pressurized, for example, by means of the same controllable control element 34 , for example, valve 34 , which is particularly controlled by the control unit 28 , wherein said valve 34 is assigned directly to the output of the hydraulic unit 27 and is arranged upstream of a branch of the conduit system 19 that distributes the pressure to connected functional units, so that the respective functional position of the control element 34 affects all elements supplied with pressure from the hydraulic unit 27 ( FIG. 3 ). [0030] Because the intermediate space 17 that is formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed, in the second operating position thereof allows access, preferably even full-body access, to press operators working with the printing unit 01 , in order to protect a press operator who might enter the intermediate space 17 or might reach into the intermediate space 17 with one of his body parts, a safety device 18 is provided in or on the printing unit 01 ( FIG. 3 ), to prevent bodily injury, particularly crushing injuries, that could occur when the movable frame part 14 is placed in motion by the first drive unit 23 , which is activated by the control unit 28 , for example, particularly automatically, i.e., in a program-controlled system. The safety device 18 has, for example, at least one additional control element 29 , for example, valve 29 , also arranged in the system for supplying power for actuating the first drive unit 23 , and controlled separately by the control unit 28 , for example, with said valve having a functional position that can be selected by the control unit 28 , in which position, for example, in the event of a malfunction occurring in the conduit system 19 for supplying power, for example, in the case of a circuit malfunction, relative movement between the frame parts 13 ; 14 is prevented, i.e., the movable frame part 14 is prevented from moving, for example, toward the stationary frame part 13 , which could endanger a press operator working in the intermediate space 17 between the frame parts 13 ; 14 , the position of which relative to one another can be changed. The selected functional position of this control element 29 , which is particularly controlled by the control unit 28 separately and independently from the control of the first drive unit 23 , affects only the operability of the first drive unit 23 . In order for the first drive unit 23 to be operable, the supply of pressurized medium to it must be enabled by the control element 29 , which is preferably controlled directly by the control unit 28 . If this supply of pressurized medium is prevented or withdrawn by the control element 29 , the first drive unit 23 is not operable, irrespective of the commands from its selection. [0031] The safety device 18 preferably also has at least one detection device 31 , particularly a sensor 31 , for example, attached to the movable frame part 14 , which sensor detects and monitors, in a contactless manner, the presence and/or movement of a body that does not belong to the printing unit 01 , i.e., particularly the presence and/or movement of a person, in the intermediate space 17 , preferably embodied as rectangular-shaped and having a variable width, between the frame parts 13 ; 14 , the position of which relative to one another can be changed. The sensor 31 preferably works with electromagnetic waves, for example, with light or microwaves (radar system), or ultrasonic waves, and is embodied, for example, as a video camera suitable for monitoring a room, or as a motion detector, wherein the motion detector is embodied, for example, as a passive infrared detector. The sensor 31 , embodied as a camera or as a motion detector, can be attached, for example, in or on the upper support of the frame 12 , which is embodied as a cover plate. Another variant provides that particularly the sensor 31 , embodied as a camera or as a motion detector, is preferably permanently affixed to the movable frame part 14 , for example, by means of a support arm 36 that is attached to said frame part 14 and supports the sensor 31 , wherein the sensing zone 37 of the sensor 31 is directed into the intermediate space 17 ( FIG. 2 ). The sensor 31 is connected to the control unit 28 , particularly to the control center 28 belonging to the printing unit 01 , at least for purposes of data transfer. As soon as the sensor 31 detects the presence and/or movement of a person in the intermediate space 17 , while the first drive unit 23 that drives the movable frame part 14 is actuated, the movement of the first drive unit 23 is immediately halted via the control element 29 acting on said drive unit 23 , and the direction of movement of the frame part is optionally reversed. When a person is detected in the hazardous area, for example, the movable frame part 14 can be brought to a halt almost instantaneously, within an adjustment path S of fewer than 5 mm, for example, by an actuation of at least one of the control elements 29 ; 34 by switching off the first drive unit 23 , i.e., switching it to pressureless, and/or by activating a brake device actuated by the control unit 28 . [0032] FIG. 3 illustrates, by way of example in a block diagram, the interaction of the at least one sensor 31 , the control unit 28 , the control elements 29 ; 34 , the energy storage device 27 , the drive units 23 ; 24 and the locking system 26 , wherein the respective direction of action is indicated in each case by an arrow, wherein particularly the sensor 31 and the control element 29 arranged in the conduit system 19 to the first drive unit 23 are assigned to the safety device 18 . The control unit 28 verifies the functional readiness and/or functionality of the sensor 31 , preferably on a continuous basis. If the sensor 31 is not functionally ready and/or functional, the control unit 28 will prevent a release for initiating a movement of the movable frame part 14 , or the control unit 28 will stop the first drive unit 23 that drives the movable frame part 14 by issuing a corresponding control command, for example, to the valve 34 assigned to the energy storage unit 27 and/or to the energy storage unit 27 itself, wherein the latter variant is indicated in FIG. 3 by a dashed directional arrow. If the sensor 31 is not functionally ready and/or functional, alternatively or in addition to controlling the first drive unit 23 and/or at least one of the control elements 29 ; 34 , the control unit 28 can then actuate the locking system 26 that locks the movable frame part 14 in place. [0033] FIGS. 4 and 5 each show, in a simplified illustration, a plan view of the printing unit 01 depicted in FIGS. 1 and 2 , with the frame parts 13 ; 14 , the position of which relative to one another can be changed within the frame 12 . [0034] In one advantageous embodiment, the at least one sensor 31 , which monitors the intermediate space 17 between the frame parts 13 ; 14 , the position of which relative to one another can be changed, has a directional characteristic 32 along the joining surface 16 of said frame parts, for example, which characteristic extends like a curtain within the intermediate space 17 , preferably a very short distance a, in the range of a few millimeters to at most a few centimeters, for example, particularly in front of the movable frame part 14 , wherein a field width w of a first angular field of the directional characteristic 32 or of the sensing zone 37 of the sensor 31 , said width being directed parallel to the adjustment path S of the movable frame part 14 , is preferably much smaller than a field width u; v, orthogonal thereto, of a second and/or third angular field of said directional characteristic 32 or said sensing zone 37 , wherein the field width u of the second angular field of the directional characteristic 32 is oriented in the axial direction of the at least one printing couple cylinder 04 mounted in the movable frame part 14 ( FIG. 4 ), and the field width v of the third angular field of the directional characteristic 32 or the sensing zone 37 is oriented in the direction of a height H of the movable frame part 14 ( FIG. 2 ). The directional characteristic 32 or the sensing zone 37 are therefore heavily concentrated at least in a direction in space which is opposite at least one of the two other orthogonal directions in space, and therefore the directional characteristic 32 or the sensing zone 37 preferably extends flat along the joining surface 16 of the movable frame part 14 . The field width u of the second angular field of the directional characteristic 32 or the sensing zone 37 , which width is oriented in the axial direction of the at least one printing couple cylinder 04 , and/or the field width v of the third angular field of the directional characteristic 32 or the sensing zone 37 , which width is oriented in the direction of the height H of the movable frame part 14 , can each be widened using an optical system, for example, particularly a system of lenses. The second angular field of the directional characteristic 32 or of the sensing zone 37 , which angle is oriented in the axial direction of the at least one printing couple cylinder 04 mounted in the movable frame part 14 , can be opened up to the height H of said frame part 14 , and the third angular field of the directional characteristic 32 or of the sensing zone 37 , oriented in the direction of the height H of the movable frame part 14 , can be opened over an entire width B of the movable frame part 14 , said width extending in the axial direction of the printing couple cylinder 04 mounted in the movable frame part 14 ( FIG. 4 ). In FIG. 4 , which provides a plan view of the printing unit 01 , in the interest of clarity, the at least one printing couple cylinder 04 with its rotational axis indicated is shown in only one frame part, namely the stationary frame part 13 , even though at least one printing couple cylinder 04 is also mounted in the movable frame part 14 (see FIG. 2 ). [0035] In another variant, the at least one sensor 31 that monitors the intermediate space 17 is arranged so as to pivot, so that the sensing zone 37 of the sensor 31 , which in this variant is preferably embodied as beam-shaped and therefore narrow, extends along the joining surface 16 formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed, as a result of a preferably periodic pivoting movement of said sensor 31 , wherein in this variant, the sensor 31 is preferably embodied as at least one laser, wherein the laser emits a beam having a narrow diameter of, for example, fewer than 2 mm, and scans a scanning zone defined by the pivoting movement of said sensor 31 . Therefore, irrespective of the practical embodiment of the sensor 31 , the sensing zone 37 of said sensor 31 can execute a pivoting movement, wherein the sensing zone 37 extends along the joining surface 16 formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed. [0036] It is also advantageous to provide that the control unit 28 which is connected to the sensor 31 activates and/or evaluates the signals from the at least one sensor 31 that monitors the intermediate space 17 , which is preferably embodied as rectangular in shape and particularly having a variable width, on the basis of the operating positions of the interacting frame parts 13 ; 14 . In this case it is particularly provided that, when the frame parts 13 ; 14 , the position of which relative to one another can be changed, are moving toward one another, the control unit 28 switches the sensor 31 to mute once a predefined distance x between said frame parts 13 ; 14 is reached, i.e., that the control unit 28 does not evaluate the sensor's signal elicited by the detection of a frame part 13 ; 14 as a malfunction, and therefore also does not halt the movement of the frame parts 13 ; 14 , the position of which relative to one another can be changed. The distance x at which the control unit 28 switches the sensor 31 to mute is selected to be greater than a field width w of the directional characteristic 32 or of the sensing zone 37 of the sensor 31 , wherein said field width w is oriented parallel to the adjustment path S of the frame parts 13 ; 14 , the position of which relative to one another can be changed. Switching the sensor 31 to mute can alternatively or additionally be time-dependent, particularly dependent on a duration of the movement carried out by at least one of the frame parts 13 ; 14 , the position of which relative to one another can be changed. In its active time, during which it is switched on, the sensor 31 monitors the intermediate space 17 preferably continuously, with its directional characteristic 32 or its sensing zone 37 . [0037] Because once the sensor 31 has been switched to mute there is a danger that the movement of the frame parts 13 ; 14 , the position of which relative to one another can be changed, toward one another in the intermediate space 17 might cause injury to a press operator, for example, to his limbs if these are reaching into the intermediate space 17 , the safety device 18 is preferably expanded to include additional components, wherein the control device 28 activates these additional components either no earlier than the start of movement of the frame parts 13 ; 14 , the position of which relative to one another can be changed, and/or no later than simultaneously with the switching of the sensor 31 to mute. These additional components connected to the control unit 28 consist preferably of an access control device 33 ( FIG. 3 ), which controls at least one access point, for example, formed on a longitudinal side of the printing unit 01 , to the intermediate space 17 that remains once the sensor 31 has been switched to mute. [0038] The access control device 33 can have one or more photoelectric beam detectors or one or more infrared beam barriers, for example, wherein the respective beam paths of the photoelectric beam detectors or infrared beam barriers are oriented horizontally or vertically, for example. The access control device 33 can perform a control function, for example, over the entire height H of at least the movable frame part 14 , or over only one or more portions of this height H. [0039] The access control device 33 can have a scanner 38 , arranged, for example, near the base plate, for example, at a height h of up to 200 mm, preferably about 100 mm, which therefore acts in the floor area of the intermediate space 17 , wherein the sensing zone 37 of said scanner 38 is oriented substantially parallel to the longitudinal side of the printing unit 01 , wherein at least one length l of said sensing zone 37 , oriented parallel to the longitudinal side of the printing unit 01 , can preferably be adjusted to variable lengths in the control unit 28 , wherein said variable length l is adjustable and adjusted particularly on the basis of the distance x formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed ( FIG. 2 ). The distance x ranges, for example, up to 2,000 mm. The base plate of the intermediate space 17 formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed, can also be covered by a pressure sensor mat (not shown), which sends a signal to the control unit 28 when the pressure sensor mat detects the presence of a person in the intermediate space 17 on the basis of the contact of that person with the base. [0040] An additional or alternative embodiment of the access control device 33 can consist, for example, of at least one sensor strip 39 , consisting of multiple sensors 41 arranged in a row, and particularly attached to the upper support of the frame 12 , with each such strip monitoring one of the access points, formed on a longitudinal side of the printing unit 01 , to the intermediate space 17 that is formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed, with said monitoring involving sensing by means of a barrier, for example, a multiple infrared beam barrier, preferably of narrow mesh, and generated, for example, by the sensors 41 in the respective sensor strip 39 . The individual sensors 41 of the respective sensor strip 39 can preferably be activated and/or deactivated on the basis of the distance x that is formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed, such that the control unit 28 will evaluate only the signal of those sensors 41 of the sensor strip 39 which are active at a given point in time for the variable-width access point to the intermediate space 17 . All the sensors 41 of the respective sensor strip 39 are switched off, for example, only when the printing unit 01 is in a printing process. As described above, each of the sensors 41 can be embodied as a camera or as a motion detector or as a laser or as a radar system. [0041] As shown in FIG. 5 , additionally or alternatively to one of the aforementioned variants, the access control device 33 can also have a mechanical safety barrier 42 on at least one of the longitudinal sides of the printing unit 01 , wherein said safety barrier 42 is embodied, for example, in the form of a sliding door, wherein said sliding door, attached to one of the frame parts 13 ; 14 , for example, mounted in a rail, can be displaced lengthwise along the longitudinal side of the printing unit 01 , at least on the basis of the movement of the frame parts 13 ; 14 , the position of which relative to one another can be changed, wherein the direction of movement of the safety barrier is indicated in FIG. 5 by a double arrow. Thus the safety barrier 42 , in its operating state in which it blocks access to the intermediate space 17 , is embodied as having a variable width between the frame parts 13 ; 14 , the position of which relative to one another can be changed. When access to the intermediate space 17 between the frame parts 13 ; 14 , the position of which relative to one another can be changed, and which have been moved away from one another is to be blocked, the sliding door attached to one of the frame parts 13 ; 14 is connected to the respectively other frame part 13 ; 14 , in that the sliding door is suspended from said part in a lock 43 . The lock 43 has an electrical contact switch, for example, which sends a signal to the control unit 28 reporting the blocking of the relevant access to the intermediate space 17 between the frame parts 13 ; 14 , the position of which relative to one another can be changed, and which have been moved away from one another. Then, a probing device 44 , for example, a sliding element 44 , which can preferably be lowered into and raised out of the base plate of the printing unit 01 , can be erected at least in the floor area of the intermediate space 17 and moved through the intermediate space 17 along the width B of the printing unit 01 , as indicated in FIG. 5 by a motion arrow, in order to verify that no person or other object, such as a tool or similar object that may have been left behind, is still present in the intermediate space 17 after the safety barrier 42 has been activated. On the side of the sliding element 44 that is directed into the intermediate space 17 at least one contact switch 46 is provided, for example, which is capable of detecting contact with a person or with an object still present in the intermediate space 17 . Alternatively, this verification can also be performed in a contactless manner, for example, using optical means, for example, with the sensor 31 embodied as a camera. Once it has been verified that no persons or objects are present in the intermediate space 17 , a release signal is sent to the control unit 28 , whereupon the control unit 28 actuates the first drive unit 23 , whereby the frame parts 13 ; 14 , the position of which relative to one another can be changed, and which have been moved away from one another, are moved toward one another along their adjustment path S, thereby reducing the width of the intermediate space 17 to its minimal value, preferably to zero. The control element 29 arranged in the conduit system 19 for supplying power to the first drive unit 23 can also be controlled by the control unit 28 on the basis of the signal from the probing device 44 that monitors the intermediate space 17 and/or from the safety barrier 42 . [0042] The access control device 33 can be permanently or only temporarily present at the respective access point to the intermediate space 17 . At least a part of the access control device 33 can have an off-line position and an operational position, wherein in the off-line position, the corresponding part of the access control device 33 is mechanically covered or moved into a protected position, in order to protect it against soiling or damage. The at least one sensor 31 for monitoring the intermediate space 17 and the access control device 33 are activated by the control unit 28 , for example, alternatingly, on the basis of the respective operating position of at least the movable frame part 14 . As was described above, the control unit 28 immediately halts the movement of the movable frame part 14 when the sensor 31 and/or the access control device 33 detect the presence and/or movement of a body not belonging to the printing unit 01 , particularly a press operator, present in a hazardous area of the printing unit 01 which has been created by a movement of the movable frame part 14 . [0043] A further improvement of the safety device 18 consists in locating a warning area 47 in front of the intermediate space 17 formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed, which space is monitored by the at least one sensor 31 , wherein the warning area 47 , which extends particularly along the longitudinal side of the printing unit 01 , is scanned either by a sensor 48 provided especially for this purpose ( FIG. 4 ) and/or by the sensor 31 that monitors the intermediate space 17 , wherein in this case the scanning zone 37 of the sensor 31 that monitors the intermediate space 17 overlaps with the intermediate space 17 . On the basis of the presence and/or movement within the warning area 47 of a body not belonging to the printing unit 01 while the frame parts 13 ; 14 are interacting, the control unit 28 , which is connected to at least one of the sensors 31 ; 48 , will activate a switchover from one operating position of the frame parts to the other, or will halt a movement that has already begun, in the event of a potential hazard. Monitoring the warning area 47 allows the control unit 28 to cause the safety device 18 and/or the drive units 23 ; 24 and/or the locking system 26 to react quickly when a person approaches the printing unit 01 or at least one of the moving frame parts 13 ; 14 in a manner that could cause harm to that person. Like the sensor 31 that monitors the intermediate space 17 , the sensor 48 specifically for monitoring the warning area 47 is embodied, for example, as a camera or as a motion detector or as a laser or as a radar system, and works, for example, with electromagnetic waves, for example, light or radar, or ultrasonic waves. The sensor 48 that monitors the warning area 47 can have a directional characteristic 32 or a sensing zone 37 having a substantially oval or elliptical cross-section, with which it monitors the warning area 47 in front of the intermediate space 17 formed between the frame parts 13 ; 14 , the position of which relative to one another can be changed. [0044] A further embodiment of the sensor 48 that monitors the warning area 47 can consist of an arrangement of at least one of the sensors 48 that projects into the warning area 47 , wherein preferably a plurality of said sensors 48 are arranged particularly close to one another in a row. The sensor 48 is preferably arranged on the movable frame part 14 , for example, in the area of the cover plate belonging to said frame part 14 , wherein the directional characteristic 32 or the sensing zone 37 of this sensor 48 is oriented particularly vertically downward, such that said sensor 48 will detect a person or an object moving on the side of the movable frame part 14 that faces the intermediate space 17 , through the access point to said intermediate space 17 that extends longitudinally along the printing unit 01 , and into said space ( FIG. 4 ). A mesh width m between the respective directional characteristic 32 or the respective sensing zone 37 of sensors 48 that monitor the same warning area 47 is only a few millimeters, for example, particularly fewer than 20 mm, preferably from 8 mm to 15 mm. The sensor 48 for monitoring a warning area 47 is positioned at a distance y of fewer than 20 mm, for example, preferably from 8 mm to 15 mm, from an edge 49 of the movable frame part 14 , which edge extends vertically, for example, and is formed on the joining surface 16 . The depth t of the warning area 47 , referred to the longitudinal side of the printing unit 01 , and extending in the direction of its width B, is 500 mm to 1,000 mm, for example. [0045] The aforementioned embodiments for monitoring the intermediate space 17 and/or the warning area 47 can also be combined with one another. For example, at least on one side of one of the interacting frame parts 13 ; 14 , a barrier 51 (indicated by dashed lines in FIG. 4 ) can be permanently or temporarily attached, extending widthwise from said frame part, to which barrier, in turn, a mechanical or contactless safety barrier 42 , according to the above-described examples, is arranged, at a lateral distance z from the relevant longitudinal side of the printing unit 01 . The distance z corresponds, for example, to the depth t of the warning area 47 . [0046] While a preferred embodiment of a printing unit of a printing press comprising at least two frame parts, the position of which relative to one another can be changed, has been described fully and completely hereinabove, it will be apparent to one of skill in the art that various changes, for example, in the specific structure of the printing unit components, the types of materials being printed on, the drives for the printing unit components, and the like could be made without deviating from the spirit and scope of the present invention which is accordingly to be limited only by the appended claims.	A printing unit of a printing press is comprised of at least two frame parts, the position of at least one of which, relative to the other, can be changed. Cooperating ones of these frame parts are placed against each other along a common joining surface, in a first operational position. These frame parts are separated from each other in a second operational position. An interstice, that is partly defined by these frame parts, is formed between the separated frame parts in the printing unit. At least one of the cooperating frame parts is supported so that it is movable along an adjustment path. At least one sensor is provided and is usable to monitor the interstice. The sensor has orientation characteristics or a sensory range along the joining surface. An aperture width of a first angular aperture of the orientation characteristics or of the sensory range is smaller than a respective aperture width of a second or third angular aperture of the orientation characteristic or sensory range. The aperture width of the first angular aperture of the orientation characteristic or the sensory range is oriented parallel to the adjustment path of the movable frame path. The aperture width of the second angular aperture of the orientation characteristic or the sensory range is oriented in an axial direction of at least one printing group cylinder which is mounted on the movable frame panel. An aperture width of the third angular aperture of the orientation characteristic or the sensory range is oriented in the direction of a height of the movable frame panel.	1

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