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BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention involves a fuel composition that includes a combination of detergents and methods that utilize the fuel composition to operate and to control deposits in an internal combustion engine. [0003] 2. Description of the Related Art [0004] Hydrocarbon fuels generally contain substances that tend to form deposits in the fuel delivery system of an internal combustion engine such as the fuel injectors in diesel engines and the intake valves in gasoline engines. These deposits, if allowed to build up, can significantly reduce engine performance in terms of power output, fuel economy and exhaust emissions. It is highly desirable to incorporate detergents into hydrocarbon fuels that are effective in controlling deposits by inhibiting their formation and facilitating their removal so that engine performance is maintained or improved. [0005] Graiff et al. in European Publication No. EP 534551A1 published on Mar. 31, 1993 disclose a gasoline composition that comprises a gasoline and a mixture of a) a polyamine selected from the group consisting of an aliphatic alkylene polyamine containing at least one olefinic polymer, a Mannich polyamine, and mixtures of the aliphatic alkylene polyamine and the Mannich polyamine and b) a hydrocarbyl poly(oxyalkylene) aminocarbamate. [0006] Cunningham et al. in U.S. Pat. No. 5,679,116 issued Oct. 21, 1997 disclose fuel additive compositions comprising a) at least one detergent/dispersant which is a derivative of a hydrocarbon-substituted dicarboxylic acid or anhydride, a hydrocarbon having a polyamine attached, and/or a Mannich condensation product, b) a cyclopentadienyl complex of a transition metal and c) a liquid carrier or additive induction aid. [0007] Croudace et al. in International Publication No. WO 90/10051 published Sep. 7, 1990 disclose a fuel composition comprising a gasoline and an additive combination comprising one or more C 6 + primary amines, one or more gasoline dispersants selected from the group consisting of polyalkylamines and Mannich bases, and a fluidizer oil. [0008] Daly in U.S. Pat. No. 5,873,917 issued Feb. 23, 1999 discloses a fuel composition comprising a gasoline, a polyether alcohol, a hydrocarbylphenol, and optionally a third component comprising a nitrogen-containing dispersant to include hydrocarbyl-substituted amines, Mannich dispersants, and polyetheramines. [0009] Wright in U.S. Pat. No. 5,169,410 issued Dec. 8, 1992 discloses a method to stabilize gasoline mixtures comprising adding to the gasoline a combination of a phenylenediamine having at least one N—H group and a strongly basic organo-amine comprising a Mannich reaction product. [0010] The present invention is directed to a fuel composition that includes a combination of two nitrogen-containing detergents and that is unexpectedly much more effective and efficient in controlling deposits in a hydrocarbon fueled internal combustion engine compared to fuel compositions that include a combination of either nitrogen-containing detergent with a fluidizer. SUMMARY OF THE INVENTION [0011] It is an object of the present invention to control deposits in an internal combustion engine so that engine performance is maintained or improved. [0012] An additional object of this invention is to control deposits in a gasoline engine. [0013] Another object of this invention is to control deposits in a diesel engine. [0014] The objects, advantages and embodiments of the present invention are in part described in the specification and in part are obvious from the specification or from the practice of this invention. Therefore, it is understood that the invention is claimed as described or obvious as falls within the scope of the appended claims. [0015] To achieve the foregoing objects in accordance with the invention as described and claimed herein, a fuel composition of this invention useful for a spark or a compression ignition internal combustion engine comprises a hydrocarbon fuel, a combination of nitrogen-containing detergents comprising a hydrocarbyl-substituted polyamine and a Mannich reaction product of an alkyl-substituted hydroxyaromatic compound with an aldehyde and a polyamine having at least one reactive N—H group, and optionally a fluidizer comprising a polyether, a polyetheramine, or mixtures thereof where the weight ratio of the hydrocarbyl-substituted polyamine to the Mannich reaction product is about 0.2:1 to 1:0.2, where each of the nitrogen-containing detergents is present at about 20-100 ppm by weight, and where the weight ratio of the fluidizer to the combination of nitrogen-containing detergents is less than 0.5 [0016] Another embodiment of this invention is a method of operating an internal combustion engine which comprises fueling the engine with the fuel composition of this invention where the hydrocarbon fuel is a gasoline or a diesel fuel, and where the gasoline or diesel fuel optionally contains an oxygenate comprising methanol, ethanol, methyl tert-butyl ether, ethyl tert-butyl ether, methyl tert-amyl ether, or mixtures thereof. [0017] A further embodiment of this invention is a method of controlling deposits in an internal combustion engine which comprises fueling the engine with the fuel composition of this invention where the hydrocarbon fuel is a gasoline or a diesel fuel, and where the gasoline or diesel fuel optionally contains an oxygenate comprising methanol, ethanol, methyl tert-butyl ether, ethyl tert-butyl ether, methyl tert-amyl ether, or mixtures thereof. DETAILED DESCRIPTION OF THE INVENTION [0018] A fuel composition of the present invention useful for a spark or a compression ignition internal combustion engine comprises a hydrocarbon fuel; a combination of nitrogen-containing detergents comprising a hydrocarbyl-substituted polyamine and a Mannich reaction product of an alkyl-substituted hydroxyaromatic compound, an aldehyde and a polyamine having at least one reactive N—H group; and optionally a fluidizer comprising a polyether, a polyetheramine, or mixtures thereof where the weight ratio of the hydrocarbyl-substituted polyamine to the Mannich reaction product is about 0.2:1 to 1:0.2, each of the nitrogen-containing detergents is present at about 20-100 ppm by weight, and the weight ratio of the fluidizer to the combination of nitrogen-containing detergents is less than 0.5 [0019] The hydrocarbon fuel of the present invention is well known to those skilled in the art. Hydrocarbon fuels are generally derived from petroleum by various refinery processes. The hydrocarbon fuel can be a gasoline or a diesel fuel. The gasoline or diesel fuel optionally can contain an oxygenate or oxygen-containing molecule up to a level of about 25% by weight of oxygenate. Oxygenates include alcohols, ethers, ketones, esters, nitroalkanes, or mixtures thereof. Commonly used oxygenates include methanol, ethanol, methyl tert-butyl ether, ethyl tert-butyl ether, methyl tert-amyl ether, or mixtures thereof. Gasoline, suitable for use in spark ignition engines, generally boils in the range from 30 to 230° C. and has a research octane number typically in the range of about 90 to 100. Diesel fuel, suitable for use in compression ignition engines, generally boils in the range from 140 to 400° C. and has a cetane number in the range from 25 to 60. [0020] The hydrocarbyl-substituted polyamine of the present invention has a hydrocarbyl substituent with a number average molecular weight of about 500 to 5000, preferably about 700 to 2000, and more preferably about 900 to 1500. The hydrocarbyl substituent is a univalent radical of carbon atoms that is predominantly hydrocarbon in nature but can have nonhydrocarbon substituent groups to include hydroxy groups and can contain heteroatoms. The hydrocarbon substituent can be derived from a polyolefin having a number average molecular weight as described above for the hydrocarbyl substituent. The polyolefin can be a homopolymer derived from one olefin or a copolymer derived from two or more olefins. The olefin can have 2 to about 10 carbon atoms and includes ethylene, propylene, butene isomers, decene isomers, and mixtures of two or more thereof. The polyolefin includes polyethylenes, polypropylenes, polybutenes and copolymers of ethylene and propylene. A preferred polyolefin is a polyisobutylene prepared by polymerization of a refinery stream containing about 30 to 60% by weight isobutylene using a Lewis acid catalyst such as aluminum trichloride or boron trifluoride. The polyolefin can be a polyisobutylene having at least 70% of its olefin double bonds at a terminal position on the carbon chain as the highly reactive vinylidene isomer which is also described below for the Mannich reaction product. [0021] The polyamine portion of the hydrocarbyl-substituted polyamine of the present invention is derived from a polyamine containing two or more amine nitrogen atoms and having at least one reactive N—H group. The polyamine can be aliphatic, cycloaliphatic, heterocyclic or aromatic and includes alkylenediamines, polyalkylenepolyamines, and hydroxy-containing polyamines. Polyamines that can be used in preparing the hydrocarbyl-substituted polyamine include ethylenediamine, 1,3-propylenediamine, N,N-di-methyl-1,3-propanediamine, N-aminoethylpiperazine, N-aminopropylmorpholine, N,N′-di-butyl-para-phenylenediamine, diethylenetriamine, triethylenetetramine, 2-(2-aminoethylamino)ethanol, and mixtures thereof. In another instance the hydrocarbyl-substituted polyamine is derived from the group consisting of ethylenediamine, diethylenetriamine, N,N-dimethyl-1,3-propanediamine, 2-(2-aminoethylamino)ethanol, and mixtures thereof. [0022] The hydrocarbyl-substituted polyamine can be prepared from the polyolefin and the polyamine as detailed above by several methods as described in U.S. Pat. No. 6,193,767 to include 1) halogenating a polyolefin followed by reaction with a polyamine, 2) hydroformulating a polyolefin followed by reaction with a polyamine and finally hydrogenation of the aldehyde-polyamine reaction intermediate, and 3) epoxidizing a polyolefin followed by reductive amination or amination with a polyamine to form a polyamine or hydroxy-containing polyamine derivative respectively. A preferred method of preparation involves chlorinating a polyisobutylene so that it contains at least one chlorine atom. The chlorinated polyisobutylene is then reacted with the polyamine generally at elevated temperatures of about 120° C. or higher. A solvent can be used to facilitate the reaction. Excess polyamine can be used to avoid cross-linking to include dimer formation as well as aid in hydrogen chloride removal although an inorganic base such as sodium hydroxide or sodium carbonate is usually employed to remove the hydrogen chloride. U.S. Pat. No. 5,407,453 describes the method of halogenating a polyolefin followed by reaction with a polyamine. [0023] The Mannich reaction product of the present invention is derived from the reaction of an alkyl-substituted hydroxyaromatic compound, an aldehyde, and a polyamine having at least one reactive N—H group. The hydroxyaromatic portion of the alkyl-substituted hydroxyaromatic compound comprises phenol, ortho-cresol, or mixtures thereof. The alkyl-substituent of the alkyl-substituted hydroxyaromatic compound can be derived from a polyolefin which can be a homopolymer, copolymer, or mixtures thereof. The polyolefin can have a number average molecular weight of about 200 to 5000, preferably about 300 to 3000, and more preferably about 400 to 1500. In one instance the polyolefin can have a number average molecular weight of about 400 to 700 and in another instance about 900 to 1500. These polyolefins can be prepared from olefin monomers of 2 to about 10 carbon atoms to include ethylene, propylene, isomers of butene, isomers of decene and mixtures of two or more thereof. The polyolefins include polyethylenes, polypropylenes, polybutenes and copolymers of ethylene and propylene. A preferred polyolefin is a polyisobutylene derived from a refinery stream having an isobutylene content of about 30 to 60% by weight. A more preferred polyolefin is a polyisobutylene having at least 70% of its olefinic double bonds at a terminal position on the carbon chain as the vinylidene type. Highly reactive polyisobutylenes having a high vinylidene isomer content include Glissopal® marketed by BASF. The alkyl-substituted hydroxyaromatic compound can be prepared by well known methods including alkylating a hydroxyaromatic compound such as phenol with a polyolefin such as polyisobutylene using a Lewis acid catalyst like boron trifluoride. [0024] The aldehyde used to prepare the Mannich reaction product of the present invention can be an aldehyde having 1 to about 6 carbon atoms. Formaldehyde is preferred and can be used in one of its reagent forms such as paraformaldehyde and formalin. [0025] The polyamine used to prepare the Mannich reaction product of the present invention contains at least two or more amine nitrogen atoms and has at least one reactive N—H group capable of undergoing the Mannich reaction. The polyamine includes alkylenediamines, polyalkylenepolyamines, polyamines containing hydroxy groups and cyclic polyamines. The Mannich reaction product can be derived from the group consisting of ethylenediamine, propylenediamine, N,N-dimethylethylenediamine, N,N′-dimethylethylenediamine, N,N,N′-trimethylethylenediamine, N,N-dimethylpropylenediamine, N,N′-dimethylpropylenediamine, diethylenetriamine, triethylenetetramine, 2-(2-aminoethylamino)ethanol, 4-(3-aminopropyl)morpholine, and mixtures thereof. [0026] The Mannich reaction product of the present invention can be prepared by reacting the alkyl-substituted hydroxyaromatic compound, aldehyde and polyamine by well known methods including the method described in U.S. Pat. No. 5,876,468. [0027] The fluidizer of the present invention comprises a polyether, a polyetheramine, or mixtures thereof. The polyether of the present invention can be represented by the formula RO[CH 2 CH(R 1 )O] x H where R is a hydrocarbyl group; R 1 is selected from the group consisting of hydrogen, alkyl groups of 1 to about 14 carbon atoms, and mixtures thereof; and x is a number from 2 to about 50. The hydrocarbyl group R is a univalent hydrocarbon group as described above for the hydrocarbyl-substituted polyamine, has one or more carbon atoms, and includes alkyl and alkylphenyl groups having about 7 to 30 total carbon atoms, preferably about 9 to 25 total carbon atoms, and more preferably about 11 to 20 total carbon atoms. The repeating oxyalkylene units are preferably derived from ethylene oxide, propylene oxide, and butylene oxide. The number of oxyalkylene units x is preferably about 10 to 35, and more preferably about 18 to 27. The polyether of the present invention can be prepared by various well known methods including condensing one mole of an alcohol or alkylphenol with two or more moles of an alkylene oxide, mixture of alkylene oxides, or with several alkylene oxides in sequential fashion usually in the presence of a base catalyst. U.S. Pat. No. 5,094,667 provides reaction conditions for preparing a polyether. Suitable polyethers are commercially available from Dow Chemicals, Huntsman, ICI and include the Actaclear® series from Bayer. [0028] The polyetheramine of the present invention can be represented by the formula R[OCH 2 CH(R 1 )] n A where R is a hydrocarbyl group as described above for polyethers; R 1 is selected from the group consisting of hydrogen, alkyl groups of 1 to 14 carbon atoms, and mixtures thereof; n is a number from 2 to about 50; and A is selected from the group consisting of —OCH 2 CH 2 CH 2 NR 2 R 2 and —NR 3 R 3 where each R 2 is independently hydrogen or a hydrocarbyl group of one or more carbon atoms, and each R 3 is independently hydrogen, a hydrocarbyl group of one or more carbon atoms, or —[R 4 N(R 5 )] p R 6 where R 4 is C 2 -C 10 alkylene, R 5 and R 6 are independently hydrogen or a hydrocarbyl group of one or more carbon atoms, and p is a number from 1 to about 7. The polyetheramine is preferably derived from ethylene oxide, propylene oxide, or butylene oxide. The number of oxyalkylene units n in the polyetheramine is preferably about 10 to 35, and more preferably about 18 to 27. The polyetheramine of the present invention can be prepared by various well know methods. A polyether derived from an alcohol or alkylphenol as described above can be condensed with ammonia, an amine or a polyamine in a reductive amination to form a polyetheramine as described in European Publication No. EP 310875. Alternatively, the polyether can be condensed with acrylonitrile and the nitrile intermediate hydrogenated to form a polyetheramine as described in U.S. Pat. No. 5,094,667. Polyetheramines where A is —OCH 2 CH 2 CH 2 NH 2 are preferred. Polyetheramines are commercially available in the Techron® series from Chevron and in the Jeffamine® series from Huntsman. [0029] The fuel composition of the present invention includes a combination of nitrogen-containing detergents comprising a hydrocarbyl-substituted polyamine and a Mannich reaction product as described above which can be in a weight ratio of the polyamine to the Mannich reaction product of about 0.2:1 to 1:0.2 and in other embodiments of about 0.5:1 to 1:0.5, of about 0.75:1 to 1:0.75, and of about 1:1. Each of the nitrogen-containing detergents can be present in the fuel composition at about 20-100 ppm by weight, preferably at about 22-80 ppm by weight, and more preferably at about 24-60 ppm by weight. The fuel composition optionally includes a fluidizer comprising a polyether, a polyetheramine, or mixtures thereof as described above where the weight ratio of the fluidizer to the combination of the nitrogen-containing detergents is less than 0.5, in another embodiment less than 0.3, and in a further embodiment less than 0.2 [0030] In another embodiment of the present invention the fuel composition comprises the combination of nitrogen-containing detergents, the hydrocarbyl-substituted polyamine and Mannich reaction product, at or greater than about 60 ppm by weight as illustrated in the examples of Table 1 and 2 hereinbelow. [0031] A method of the present invention of operating an internal combustion engine comprises fueling the engine with the fuel composition of the present invention which comprises the hydrocarbon fuel, the combination of nitrogen-containing detergents, and optionally the fluidizer as described in this application. In another embodiment of the present invention, a method of controlling deposits in an internal combustion engine comprises fueling the engine with the fuel composition of the present invention as described in this application. The benefits of the methods of the present invention are illustrated in the examples of Table 1 and 2 hereinbelow. [0032] The fuel composition of the present invention can include a solvent to facilitate handling and transfer of fuel additives and fuel additive concentrates and to provide homogeneous fuel additive concentrates and fuel compositions. The solvent can be an aliphatic hydrocarbon, aromatic hydrocarbon, glycol ether, alcohol, or mixtures thereof. Examples of suitable solvents include various naphthas, various kerosenes, benzene, toluene, xylenes, aliphatic alcohols having 2 to 10 carbon atoms, or mixtures thereof. [0033] The fuel composition of the present invention can include additional fuel additives depending on the requirements of the engine it is used in. In general the fuel composition can include antioxidants such as hindered phenols, supplemental detergents like succinimides, corrosion inhibitors such as alkenylsuccinic acids, antistatic agents, biocides, demulsifiers, and additional fluidizers such as mineral oils and poly(alpha-olefins). Gasoline fuel compositions can contain antiknock additives such as methylcyclopentadienyl manganese tricarbonyl, haloalkane lead scavengers, and anti-valve seat recession additives such as alkali metal sulphosuccinate salts. Diesel fuel compositions can contain organo nitrite or nitrate cetane improvers, cold flow improvers such as copolymers of ethylene and vinyl acetate, smoke suppressants, antifoam agents like silicone fluids, and lubricity agents such as tall oil fatty acids. [0034] The fuel composition of the present invention is generally prepared by mixing the components which can include the hydrocarbon fuel, the nitrogen-containing detergents, fluidizer, solvent, and additional fuel additives at ambient temperature or at an elevated temperature of about 40 to 60° C. until the mixture is homogeneous. The various fuel additive and solvent components can be added to the hydrocarbon fuel separately but are usually added as a mixture or fuel additive concentrate which is prepared in the same way as the fuel composition. [0035] The patent documents cited in this application regarding methods of preparation are incorporated herein by reference for their disclosure of these methods of preparation. [0036] The advantages of the present invention in controlling deposits in an internal combustion engine are illustrated in the following examples in Table 1 and 2. TABLE 1 BMW a 2,500 Miles with Unleaded Gasoline Containing Ethanol A Hydrocarbyl B Ratio of Polyamine b , Mannich c , Fluidizer, Fluidizer to Intake Valve Example ppm actives ppm actives Ppm actives A + B Deposits mg 1 61.6 — 31.6 d 0.51 282 (comparative) 2 68.4 — 35.1 d 0.51 85 (comparative) 3 30.2 — 46.4 e 1.54 172 (comparative) 4 31.7 32.7 3.9 e 0.06 48 5 36.0 37.1 — — 43 [0037] [0037] TABLE 2 BMW a 2,500 Miles with Unleaded Gasoline A Hydrocarbyl B Ratio of Polyamine b , Mannich c , Polyether d , Polyether to Intake Valve Example ppm actives ppm actives ppm actives A + B Deposits, mg 6 68.4 — 35.1 0.51 25.4 (compar- ative) 7 — 57.5 28.3 0.49 23.0 (compar- ative) 8 40.0 41.2 — — 8.6	A fuel composition comprises a hydrocarbon fuel, a combination of nitrogen-containing detergents that includes a hydrocarbyl-substituted polyamine and a Mannich reaction product, and optionally a fluidizer. Methods of operating and of controlling deposits in an internal combustion engine involve fueling the engine with the fuel composition which results in unexpectedly effective and efficient control of deposits in the fuel induction system.	2
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 09/965,489 filed Sep. 27, 2001, the contents of which are incorporated by reference herein in their entirety. BACKGROUND [0002] In nearly every sector of the electronics industry, electronic circuitry involves the interconnection of an integrated chip (hereinafter “chip”) and a surface or device upon which the chip is supported. During operation of the circuitry, heat is generated and a heat flux is established between the chip and its environment. In order to remove heat more effectively to ensure the proper functioning of the circuitry, the heat flux is disseminated across a surface area larger than the surface area of the chip and transferred to an attached heat sink device. Once the heat is transferred to the heat sink device, it can be removed by a forced convection of air or other cooling means. [0003] In some applications, multiple processors and their associated control and support circuitry are arranged on a single chip. Such arrangements may result not only in a further increase in the heat flux, but also in a non-uniform distribution of the heat flux across the surface of the chip. The non-uniformity of the distribution of the heat flux is generally such that a higher heat flux is realized in the processor core region and a significantly lower heat flux is realized in the region of the chip at which the control and support circuitry is disposed. The high heat flux in the processor core region may cause devices in this region to exceed their allowable operating temperatures. The resulting disparity in temperature between the two regions, which may be significant, may contribute to the stressing and fatigue of the chip. [0004] A thermally conductive heat spreading device is oftentimes disposed between the chip and the heat sink device to facilitate the dissemination of heat from the chip. Such heat spreading devices are generally plate-like in structure and homogenous in composition and fabricated from materials such as copper, aluminum nitride, or silicon carbide. Newer carbon fiber composites exhibit even higher thermal conductivities than these traditional thermal spreader materials; however, they tend to be anisotropic in nature, exhibiting wide variations in thermal conductivity between a major axis normal to the face of the structure (in the Z direction) and the axes orthogonal to the major axis (in the X and Y directions). Moreover, the lower thermal conductivity in the direction along the major axis tends to have the effect of increasing the thermal resistance of the heat spreading device, thereby inhibiting the dissemination of heat from the device. SUMMARY [0005] A thermal spreading device disposable between electronic circuitry and a heat sink is disclosed. The device includes a substrate having a first face and a second face and a plurality of conduits extending through the substrate from the first face to the second face. The two faces of the substrate are disposed in a parallel relationship. The material of which the substrate is fabricated has a first thermal conductivity value in a direction parallel to the faces and a second thermal conductivity value in a direction normal to the faces, with the second thermal conductivity value being less than the first thermal conductivity value. The material of which each conduit is fabricated has a thermal conductivity value associated with it, with the thermal conductivity value of each conduit being greater than the second thermal conductivity value of the substrate. [0006] One method of fabricating the thermal spreading device includes arranging a plurality of thermally conductive rods such that the rods extend longitudinally in a common direction, disposing a molding material radially about the longitudinally extending rods, hardening the molding material around the plurality of thermally conductive rods, and cutting the hardened molding material into slices in a direction perpendicular to the direction in which the rods longitudinally extend. Other methods of fabrication include press fitting or shrink fitting the thermally conductive rods into holes in the substrate. BRIEF DESCRIPTION OF THE DRAWINGS [0007] The present disclosure will be better understood by those skilled in the pertinent art by referencing the accompanying drawings, where like elements are numbered alike in the several FIGURES, in which: [0008] FIG. 1 is a perspective cutaway view of a thermal spreading device; [0009] FIGS. 2A through 2C are perspective views of a batch process of the fabrication of a thermal spreading device; [0010] FIGS. 3A and 3B are perspective views of a batch process of the fabrication of a thermal spreading device in which conduits are press fitted into the substrate; [0011] FIG. 4 is a sectional view of a step in a batch process of the fabrication of a thermal spreading device in which conduits are shrink fitted into the substrate; [0012] FIG. 5 is a sectional view of the engagement of a thermal spreading device with a chip and a heat sink; [0013] FIGS. 6 and 7 are plan and cross sectional views of an alternate exemplary embodiment of a thermal spreading device; and [0014] FIG. 8 is an exploded perspective view of the engagement of the thermal spreading device of FIGS. 6 and 7 with a chip. DETAILED DESCRIPTION [0015] Referring now to FIG. 1 , an exemplary embodiment of a thermal spreading device is shown generally at 10 and is hereinafter referred to as “thermal spreader 10 .” Thermal spreader 10 is a conduction medium that provides for thermal communication between electronic circuitry (e.g., a chip) and an environment to which thermal spreader 10 is exposed. The thermal communication is effectuated by the conduction of heat across a substrate 12 to a heat sink (shown with reference to FIG. 5 ). Because the materials from which substrate 12 are fabricated are generally of an anisotropic nature, substrate 12 is oftentimes characterized by a marked disparity in thermal conductivities in orthogonal directions. In particular, the thermal conductivity of substrate 12 in a direction shown by an arrow 16 (Z direction), which is normal to the interface of thermal spreader 10 and the circuitry (not shown), may be substantially less than thermal conductivities in the directions shown by an arrow 18 (X direction) and an arrow 19 (Y direction) along the same interface of thermal spreader 10 and the circuitry. Due to such disparities, the thermal resistance across substrate 12 (in the direction of arrow 16 ) is increased, and the rate of heat transfer (flux) across thermal spreader 10 varies dramatically from the flux in the direction (as shown by arrows 18 and 19 ) that the interface extends. [0016] In order to enhance the thermal communication across thermal spreader 10 , substrate 12 is configured to include thermal conduits 14 . The materials from which thermal conduits 14 are fabricated generally have thermal conductivity values that are substantially higher than the thermal conductivity values in the Z direction of the material from which substrate 12 is fabricated. Because the flux through conduits 14 is greater than the flux in the same direction across the surrounding substrate 12 , heat conduction is enhanced across substrate 12 in the direction shown by arrow 16 (Z direction), viz., in the direction in which conduits 14 extend. Heat transfer is thereby optimized through substrate 12 via conduits 14 . [0017] Conduits 14 are defined by rods or wires having substantially circular cross sectional geometries, as is shown. Rods or wires having substantially circular cross sectional geometries enable a substantially uniform transfer of heat to be maintained in the directions radial to the circular cross section. Other cross sectional geometries that may be used include, but are not limited to, elliptical, square, flat, multi-faced, and configurations incorporating combinations of the foregoing geometries. Regardless of the cross sectional geometry, conduits 14 are formed from materials having high thermal conductivities. Such materials include, but are not limited to, copper, aluminum, carbon, carbon composites, and similar materials that exhibit a high thermal conductivity along the conduit axis. The carbon materials may be fibrous or particulate in structure. [0018] Substrate 12 provides an anchor into which conduits 14 are disposed while further providing a medium for the transfer of heat in directions along and parallel to the interface defined by the positioning of thermal spreader 10 on the chip. Exemplary materials from which substrate 12 can be fabricated include, but are not limited to, carbon and carbon composites. As noted above with respect to conduits 14 , the carbon materials may be fibrous or particulate in structure. [0019] The configuration of thermal spreader 10 is generally such that conduits 14 are arranged to be parallel to each other, as is shown in FIG. 1 . Furthermore, conduits 14 generally extend linearly between opposing surfaces of substrate 12 . As shown, the architecture of thermal spreader 10 is further defined by a substantially uniform spatial positioning of conduits 14 over any randomly selected section of substrate 12 . The even distribution of conduits 14 facilitates and improves the conduction of heat from a first face 20 disposed adjacent the chip and an opposingly-positioned second face 24 disposed adjacent the heat sink. Such a distribution provides for the effective transfer of heat longitudinally through conduits 14 while maintaining the substantially uniform transfer of the heat in the directions radial to the surfaces of conduits 14 . [0020] When thermal spreader 10 is mounted between a chip (shown with reference to FIG. 5 ) and a heat sink (also shown with reference to FIG. 5 ), conduits 14 enable heat generated during the operation of the chip to be communicated from first face 20 of thermal spreader 10 through conduits 14 across substrate 12 to second face 24 of thermal spreader 10 . Although the material of which substrate 12 is fabricated allows for some degree of thermal conduction between faces 20 , 24 , the anisotropic nature of the material causes heat generated by the chip and transferred to thermal spreader 10 to be more substantially dissipated through substrate 12 in the directions shown by arrows 18 and 19 . Dissipation of heat in the directions shown by arrows 18 and 19 allows for the heat to be conducted to a larger number of conduits 14 , which further allows for the more effective transfer of heat from the chip to the heat sink. [0021] Referring now to FIGS. 2A through 2C , an exemplary batch process illustrating the fabrication of the thermal spreader is illustrated. The process comprises arranging the rods or wires by which conduits 14 are defined into an array, which is shown generally at 30 in FIG. 2A . The rods are arranged such that the longitudinal axes of the rods are parallel to each other and held fast by a jig (not shown) or other device configured to maintain the rods in their proper alignment. Molding material of which the substrate is formed is then disposed around the rods, hardened, and cured, as is shown in FIG. 2B . The hardened and cured molding material forms a block, shown generally at 32 , having thermal conduits 14 extending between first face 20 and opposing second face 24 thereof. Block 32 is then sawed or otherwise made into sheets 34 , as is illustrated in FIG. 2C . Each sheet 34 is of a thickness t S , which is slightly in excess of the desired thickness of the finished thermal dissipating device. Sheets 34 are then polished on at least one face thereof to bring thicknesses t S within the allowable tolerances of final product. Polishing of the sheets on both sides further provides sheets 34 with surface textures conducive to a more effective transfer of heat between the chip and the heat sink. Finally, sheets 34 are cut into individual thermal spreaders 10 of the desired length and width. [0022] In another exemplary process of the fabrication of the thermal spreader, thermal conduits 14 may be press-fitted into substrate 12 , as is shown in FIGS. 3A and 3B . Referring to FIG. 3A , holes 28 are drilled, punched, or otherwise formed in block 32 . The cross sectional geometries of holes 28 correspond with the cross sectional geometries of conduits 14 insertable into holes 28 . Referring now to FIG. 3B , conduits 14 are inserted into holes 28 under a compressive force C f effectuated by a press (not shown) or a similar apparatus. The mechanical tolerances of conduits 14 are such that when conduits 14 are received in holes 28 , a tight fit is maintained between the inner surfaces of holes 28 and the outer surfaces of each conduit 14 , thereby allowing effective thermal communication to be maintained between the material of block 32 and conduits 14 . Block 32 may then be sawed or otherwise formed into sheets and polished and cut to the desired lengths and widths. [0023] In yet another exemplary process of the fabrication of the thermal spreader, thermal conduits 14 may be shrink-fitted into substrate 12 , as is shown in FIG. 4 . In the shrink-fitting process, holes 28 are again drilled, punched, or otherwise formed in block 32 , as was described above. Block 32 is heated to a temperature that causes block 32 (and subsequently holes 28 ) to expand. Upon expansion, conduits 14 are inserted into holes 28 with little effort such that space is defined by inner surfaces 34 of holes and outer surfaces 36 of conduits 14 . Block 32 is then cooled to cause the material of fabrication of block 32 to contract, thereby constricting holes 28 and eliminating the spaces defined between the inner surfaces of holes 28 and the outer surfaces of conduits 14 . Once constricted, conduits 14 are securely retained within block 28 . Block 32 may then be sawed or otherwise formed into sheets and polished and cut to the desired dimensions in manners similar to those described above to form the final product. [0024] Referring now to FIG. 5 , a thermal conduction package is shown generally at 38 . In thermal conduction package 38 , thermal spreader 10 is shown as it would be disposed between the chip 40 disposed in electronic communication with its associated circuitry through substrate 42 and the heat sink 44 . Thermal spreader 10 is adhered to chip 40 with an adhesive 48 , which may be a solder or an epoxy material applied to chip 40 as a thin layer upon which thermal spreader 10 is placed. A layer of thermal paste 50 , which is typically a natural or synthetic oil-based compound with thermally conductive particle filler, is applied to the exposed surface of thermal spreader 10 upon which heat sink 44 is mounted. Both adhesive 48 and thermal paste 50 facilitate the transfer of heat between chip 40 and thermal spreader 10 and thermal spreader 10 and heat sink 44 respectively, thereby enhancing the conduction of heat across thermal spreader 10 . [0025] As is shown with reference to FIGS. 6 and 7 , another exemplary embodiment of a thermal dissipating device is shown generally at 110 . Thermal spreader 110 is substantially similar to thermal spreader 10 as illustrated above with reference to FIGS. 1 through 5 . Thermal spreader 110 , however, includes an arrangement of variably spaced conduits 114 disposed within a dissipating substrate 112 . The arrangement of variably spaced conduits 114 is configured to define regions 150 in which the density of conduits 114 is greater than the density of conduits 114 in adjacently positioned regions 152 of the same substrate 112 . The high-density regions 150 are positioned on substrate 112 to register with areas of high heat flux on a chip upon assembly of the thermal conduction package. [0026] Referring now to FIG. 8 , the engagement of the thermal spreader with the chip is illustrated generally at 138 . When thermal spreader 110 is placed in communication with chip 140 , the high-density regions 150 register with the areas of high flux 160 on chip 140 . Such a placement allows for the increased transfer of heat from the areas of high flux 160 on chip 140 to high-density regions 150 of thermal spreader 110 while simultaneously providing a thermally adequate transfer of heat from the areas of chip 140 from which lower heat flux is realized. The disparities in the densities of the conduits in each region 150 , 152 are engineered to provide for the removal of heat from each portion of chip 140 and the transfer of heat to the heat sink to minimize disparity in heat build up at the interface of chip 140 and thermal spreader 110 . Minimization of such disparity may provide improved operability of chip 140 and increase the useful life thereof. Fabrication of thermal spreader 110 is effectuated in a batch process substantially similar to that illustrated in FIGS. 2A through 4 for thermal spreader 10 . [0027] While the disclosure has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.	A thermal spreading device disposable between electronic circuitry and a heat sink includes a substrate having parallel first and second faces and conduits extending through the substrate between the faces. The substrate material has a first thermal conductivity value in a direction parallel to the faces and a second thermal conductivity value in a direction normal to the faces, with the second thermal conductivity value being less than the first thermal conductivity value. The conduit material has a thermal conductivity value associated with it, with the thermal conductivity value being greater than the second thermal conductivity value of the substrate. One method of fabricating the thermal spreading device includes disposing a molding material radially about the rods and hardening the material. Other methods include press fitting and shrink fitting the rods into a substrate material.	8
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to bonding of breathable films as functional layers to substrates of woven or knitted fabrics by means of copolyesters. [0003] In particular, the invention relates to a method for production of a wash-resistant lamination between a film which is waterproof and permeable to water vapour on basis of copolyetherester and at least one substrate on basis of polyester as a woven fabric or knitted fabric to achieve a bonded fabric of single polymer construction. [0004] 2. Background and Prior Art [0005] The invention deals with bonding waterproof ultra light, extremely tight, but permeable to water vapour, i. e. breathable non-porous membranes or films, respectively, on basis of copolyetheresters (such as e. g. Sympatex®, mark of the Sympatex-Technologies) and textile substrates of polyester by the production of a laminate, especially a 2-layered film, consisting of the breathable film and a film of a special copolyester. The invention also relates to the bonding of this laminate (as a functional layer) by means of a copolyester hot-melt adhesive applied to the substrate and especially to the textile polyester substrate to achieve a bonded fabric of single polymer construction which consists of polyester continuously, which is completely recyclable as well as resistant to washing at 60° C., and thus which does not delaminate after multiple washings. [0006] Non-porous membranes which are waterproof but permeable to water vapour are already described variously in the literature and in patent documents. Special materials waterproof and permeable to water vapour made from copolyetheresters were described in U.S. Pat. No. 4,493,870 in 1983. Today, these materials are used worldwide under the term Sympatex®, a mark of the Sympatex-Technologies. Sympatex® is a monolithic membrane assuring that the mentioned properties remain intact with regard to impermeability to water and that the climate-favorable properties of the outer material are not reduced. For example, Sympatex® can be drawn up to 300% in each direction. The Sympatex® membrane has to have only a thickness of {fraction (1/100)} mm to be effective. [0007] The principle of the breathing-activity can be explained in that there is on the inside and the outside of the membrane a different climate characterized by different water vapour concentrations and temperatures. Thereby, a pressure difference forming the driving force for the transport of water vapour is developed. Hydrophilic components are incorporated in the membrane. The water vapour molecules are attracted by them and are transported across the membrane into direction of the lower vapour pressure by component to component transfer such as in a human hand. [0008] DE 38 83 948 T2 describes a moisture-stable film of a hydrophilic copolyester elastomer layer and a hydrophobic copolyester elastomer layer linked to each other. If the hydrophobic layer has a sufficiently low melting point in relation to the melting point of the hydrophilic layer, it can be used to bond to textile materials such as polyamide, polyethyleneterephthalate, cotton and cellulose triacetate. However, the aforesaid single polymer construction is not present. [0009] Further, it has been known for a long time that polyetherester films having textile interlinings or face fabric of polyester can be bonded only by means of reactive polyurethane systems (see EP 0 382 801 B1, column 3, 1.32-42). Also, the laminates of the breathable film and a polyester textile can be produced by means of a hot-melt adhesive using polyesters or copolyesters. But these laminates are not resistant to multiple washing at 60° C. Hitherto the latter property can thus only be reached by a bond having a reactive polyurethane system. But, by using a polyurethane adhesive the single polymer construction of the whole laminate and thus, the complete recyclability of a single polymer construction is lost. In the year 2000 a novel standard was developed from the textile industry, the so-called bluesign®—standard and related bluesign® label. [0010] The basis for this standard is the highest possible zero-emission and the saving of resources from the textile fibre up to the button and throughout the whole production process of a clothing. An important aspect of this concept is the (chemical) recycling by using polymeric fibres which is only achievable by a single polymer construction of the materials used for clothing. [0011] In relation to the use of a breathable film or membrane, respectively, in the clothing, this means, that all parts have to consist of polyester, but also all materials required for bonded structure also have to consist of polyester. Hitherto, these requirements are not fulfillable, since the wash resistance of a copolyester adhesive for bonding breathing-active films of copolyetherester and polyester textile is not present when a reactive polyurethane adhesive is used the single polymer construction is no longer present and the requirements of the bluesign®—label are not fulfilled. [0012] The technique of bonding by use of a hot-melt adhesive is well known. The hot-melt adhesive is applied on a substrate part in a known manner and subsequently fused and linked to the second substrate under pressure. The coating of the hot-melt adhesive can made either from the granule type by a “hotmelt”-coating or from the powder type by the known methods of scatter coating, double dot coating, paste coating or paste dot coating. [0013] A further method is the coating by a converted type of the hot-melt adhesive such as e.g. as film or as web. [0014] Further, woven fabrics or knitted fabrics can comprise hot-melt binding fibres. For example, DE 38 26 089 A1 describes a non-woven fabric enriched with bonding binding fibres making a hot-melt adhesive contact to the film which is waterproof and permeable to water vapour. However, in the binding which is disclosed the fibres can melt together into larger areas [0015] Only the technique of forming the bond in a dot matrix pattern is considered to bond a film permeable to water vapour, since the special properties of the film are not enabled any more by a full-area type lamination. [0016] However, despite the coating method, all bonds made between a copolyetherester film and a textile of polyester by means of a hot-melt adhesive of copolyester show a good original adhesion, but an insufficient adhesion after several washings without exception. [0017] Thus, it is object of the present invention to provide a wash-resistant bond to film on basis of copolyetherester and a textile fabric on basis of polyester using a hot-melt adhesive which is a copolyester. This object is achieved by a method for the production of a wash-resistant bond between a film on basis of copolyetherester which is waterproof and water vapour permeable and at least one woven or knitted fabric as a substrate on basis of polyester wherein said film on basis of copolyetherester is manufactured with at least one film of a hot-melt adhesive on basis of hydrophilic copolyetherester to a laminate previously before being bonded to said substrate by means of a hot-melt adhesive on basis of copolyester and wherein said film of a hot melt adhesive comprising hydrophilic copolyetheresters is formed from terephthalic acid and a combination of alcohols selected from the group consisting of butanediol, diethylene glycol, triethylene glycol and polyethylene glycols having a molecular weight of 600 to 400 g/mol, as well as by the bonded fabric made by the method; [0018] by a fabric according to the method which conforms to the bluesign® standard; and [0019] by a fabric wherein said waterproof and water vapour permeable layers is a copolyetherester comprising multiple recurring long-chain and short-chain units linked head to tail, said long chain units corresponding to formula (I). [0020] and said short claim units correspond to formula (II) [0021] wherein [0022] G represents a bivalent residue derived by removal of terminal hydroxyl groups, from at least one long-chain glycol having an average molecular weight of 600 to 6000 and an atomic ratio of carbon to oxygen between 2.0 and 4.3, wherein at least 20 wt.-% of said long-chain glycol have an atomic ratio of carbon to oxygen between 2.0 and 2.4 and are 15 to 50 wt.-% of said copolyetherester, [0023] R represents a bivalent residue derived by removal of carboxyl groups from at least one dicarboxylic acid of a molecular weight of less than 300, and [0024] D represents a bivalent residue derived by removal of hydroxyl groups from at least one diol of a molecular weight of less than 250, wherein at least 80 mol-% of used dicarboxylic acid consist of terephthalic acid or ester-forming equivalents thereof and at least 80 mol-% of said diol have said small molecular weight consisting of 1,4-butanediol or ester-forming equivalents therefore, the sum of mole percents of said dicarboxylic acid which does not represent terephthalic acid or ester-forming equivalents thereof and of said diol having a small molecular weight which does not represent 1,4-butanediol or ester-forming equivalents thereof being not more than 20% and wherein said short-chain units of ester can be 40 to 80 wt.-% of said copolyetherester. BRIEF SUMMARY OF THE INVENTION [0025] the inventors of the present application have found a method to ensure the single polymer construction of a bonded fabric, while simultaneously achieving a very good wash resistance. [0026] It has been discovered that instead of using a pure breathing-active film, e. g. of Sympatex® etc., a two-layered film consisting of the breathable film can be bonded by means of known bonding techniques to a polyester substrate which can be for example, a textile interlining or face fabric or face fabric and lining fabric using a chemically related copolyester hot meat adhesive. The very good original adhesion does not decrease upon several washings. [0027] The production of a two-layered film of the breathing-active film and the layer of the copolyetherester hot-melt adhesive (laminate) is possible by coextruding two materials as blown film or also as flat film. Alternatively, it may be from the lamination of a hot-melt adhesive film on the breathable film. DETAILED DESCRIPTION OF THE INVENTION [0028] The laminate used in the method according to the present invention can be formed as a two layered laminate or a three-layered laminate. In particular, the two-layered laminate is a face fabric laminate, an insert laminate and/or a lining laminate. In the face fabric laminate one side of the face fabric is connected directly to the membrane by means of the chemically related hot-melt adhesive film on basis of hydrophilic copolyetheresters by means of a hot-melt adhesive. The lining fabric underlies loosely. [0029] In insert laminates, the Sympatex® membrane is laminated to a textile backing such as a non-woven fabric or a knitted fabric with an added chemically related copolyester hot-melt adhesive layer and clings loosely between face fabric and lining fabric. This variant is used predominantly for fashionable clothing due to the freedom of choices allowed for the selection and construction of face fabric. [0030] In lining laminates, the lining fabric (woven fabric, knitted fabric, non-woven fabric) is connected on the first side to the membrane by means of the chemically related copolyester hot-melt adhesive layer by means of dot matrix pattern of hot-melt adhesive. The face fabric overlies it loosely. This laminate is especially preferred for extremely light and soft-textured jackets. [0031] In the three layered laminate according to the present invention the Sympatex® membrane is connected firmly to the face fabric and lining fabric over the hydrophilic copolyetherester. Three layered laminates are robust and long-lived and thus, are used especially for particularly longwearing clothing. [0032] While the thickness of the film which is waterproof and permeable to water vapour is between 5 and 50 μm, the laminated copolyester film using a hot-melt adhesive on basis of hydrophilic copolyetheresters has a thickness of 5 to 80 μm, preferably 5 to 35 μm. [0033] The hot-melt adhesive material which shall be used for the laminated film has to be closely related chemically to the used breathable film on basis of polyetherester to ensure the permeability to water vapour of the final bonded fabric. These hot-melt adhesives of hydrophilic copolyetheresters consist of terephathlic acid as a single dicarboxylic acid component and a diol mixture of butanediol, diethylene glycol and/or triethyleneglycol. In addition 2 to 10 mol-% (based on the whole amount of acid and diol) of a higher molecular polyethylene glycol component having a molecular weight of 600-4000 g/mol is added. The melting points of such copolyetheresters are between 90 and 190° C. The amount of butanediol is less than 75 mol-%. The amount of diethylene glycol is between 5 and 60 mol-%. The amount of triethyleneglycol is between 0 and 40 mol-%. Preferably the molecular amount of butanediol is between 40 and 70 mol-% based on the total amount of diol as 100 mol-%. In an especially preferred embodiment the molecular amount of diethylene glycol is between 10 and 50 mol-% and the molecular amount of triethyleneglycol is preferably between 0 and 35 mol-% based on the total amount of diol as 100 mol-%. If diethylene glycol and triethyleneglycol are used simultaneously the molecular ratio of diethylene glycol to triethyleneglycol is preferably between 5:1 and 1:3. To increase the melt viscosity of the copolyetherester hot-melt adhesive masses, a trivalent or multivalent diol of not more than 2 mol-% based on the whole amount of diol can be used. The melt viscosity of the copolyetheresters, as measured at 190° C. and load of 2.16 kg according to ISO/DIN 1133, is not below 100 Pa.s, preferably it is not below 200 Pa.s. In particular, a molecular amount of butanediol of 45-70 mol-%, an amount of diethylene glycol of 26-50 mol-% and an amount of a higher molecular polyethylene glycol component having a molecular weight of 600-4000 g/mol of 4 to 8 mol-% are considered as diol component for the hydrophilic copolyetheresters. [0034] As copolyetherester for the film or membrane waterproof and permeable to water vapour are selected copolyetheresters consisting of a multitude of recurring interlinear long-chain and short-chain units of ester being statistically linked by ester linkages head to tail, the long-chain units of ester corresponding to formula (I) [0035] and the short-chain units of ester corresponding to formula (II) [0036] wherein [0037] G represents a bivalent residue derived by removal of terminal hydroxyl groups, from at least one long-chain glycol having an average molecular weight of 600 to 6000 and an atomic ratio of carbon to oxygen between 2.0 and 4.3, at least 20 wt.-% of the long-chain glycol having an atomic ratio of carbon to oxygen between 2.0 and 2.4 and being 15 to 50 wt.-% of the copolyetherester, [0038] R represents a bivalent residue derived by removal of carboxyl groups from at least one dicarboxylic acid of a molecular weight of less than 300, and [0039] D represents a bivalent residue derived by removal of hydroxyl groups from at least one diol of a molecular weight of less than 250, at least 80 mol-% of dicarboxylic acid consisting of terephthalic acid or ester-forming equivalents thereof and at least 80 mol-% of the diol having said small molecular weight consisting of 1,4-butanediol or ester-forming equivalents therefore, the sum of mole percents of the dicarboxylic acid which does not represent terephthalic acid or ester-forming equivalents thereof and of the diol having a small molecular weight which does not represents 1,4-butanediol or ester-forming equivalents thereof being not more than 20% and wherein the short-chain units of ester can be 40 to 80 wt.-% of the copolyetherester. [0040] Appropriate copolyetheresters are described in EP 0 382 801 B1 which is incorporated by reference herein. [0041] In addition, the second layer of the composite film or the laminated hot-melt adhesive film, respectively has to be relatively high melting to avoid a fusion of the two-layered film or the laminate, respectively during bonding to the polyester face fabric. This bonding does not occur over the full area so that there is no reduction of the permeability to water vapour. Therefore, the technique of the paste dot coating is selected preferably, but also the powder dot coating or scatter coating are possible. Thereby, a copolyester powder having melting point of maximum 140° C., preferably of about 120° C. serves as hot-melt adhesive to hold the processing temperature below the melting temperature of the two-layered film or bonded film. Griltex® 9E, a produce of EMS-Griltech, Domat/Ems, Switzerland can be considered as a preferred copolyester hot-melt adhesive. [0042] The substrate, especially a face fabric, need not be compulsorily polyester. In case of such composition the single polymer construction is not present, but the present method according to the present invention has the advantage that the lamination between copolyetherester film and substrate does not have to occur directly, as required by the use of a reactive polyurethane adhesive, but that the coated substrate can be bonded in a later operating cycle to the two layered film or to the film laminate. [0043] In the following examples, the method according to the invention is explained in detail. Original adhesion and the adhesion after washing for 5 times at 60° C. were determined according to DIN 53920 as the criterion for the bond quality. Additionally, the permeability to water vapour was determined before and after washing at 60° C. according ASTM E-96-66. EXAMPLE 1 [0044] In a 101 esterification reactor provided with temperature probe, stirrer, reflux column and distillation tube 1.37 kg (1.52 mol) of butanediol, 0.98 kg (0.93 mol) of diethylene glycol and 0.89 kg (0.15 mol) of polyethylene glycol having an average molecular weight of 600 are added and fused at 140° C. under an atmosphere of nitrogen maintained during the whole reaction. Terephthalic acid 3.08 kg (1.85 mol) and 3 g of esterification catalyst are added while stirring. Upon stepwise increase of the internal temperature to 235° C. the reaction is continued until no distillate arises. Subsequently, 6 g of esterification catalyst and 3 g of heat stabilizer are added. The temperature is increased to 250° C. and vacuum is applied stepwisely until a terminal vacuum of <1 mbar is achieved. The condensation is continued for at least 2 hours until the desired viscosity is achieved. [0045] The obtained copolyetherester hot-melt adhesive has, after drying for 12 hours at 60° C. a melting point of about 157° C., a glass transition temperature Tg of about 0° C. and a melting viscosity of 400 Pa.s, as measured at 190° C. and load of 2.16 kg. EXAMPLE 2 [0046] On a flat film installation (manufacturer: Company Collin, Ebersberg, Germany) a two-layered film was produced from Sympatex® (mark of the Sympatex-Technologies) and the hot-melt adhesive of Example 1. Each layer has a thickness of about 25 μm. EXAMPLE 3 [0047] A film from Sympatex® (mark of the Sympatex-Technologies) was laminated to a film of the hot-melt adhesive of Example 1. The hot-melt adhesive film was produced on a flat film installation (manufacturer: Company Collin, Ebersberg, Germany) with a thickness of 25 μm. The Sympatex® film was pressed with the hot-melt adhesive film according to the present invention on a Meyer press at 155° C. under a pressure of 5 N/cm 2 for 8 seconds. EXAMPLE 4 [0048] A commercial polyester face fabric and the two-layered film of Example 2 were bonded with a copolyester hot-melt adhesive (Griltex® 9E from EMS-Griltech) on basis of modified polybutyleneterephthalate having a melting point of 119° C. by means of a powder dot coating. Thereby, the polyester face fabric was bonded to the hot-melt adhesive side of the two-layered film. The copolyester hot-melt adhesive was applied in the powder fraction 80-200 μm and with a coating weight of 12 g/m 2 on the face fabric and sintered. The bond to the two-layered film was carried out on a Meyer press at 135° C., a pressure of 5 N/cm 2 and a residence time of 12 seconds. EXAMPLE 5 [0049] A commercial polyester face fabric and the film laminate of Example 3 were bonded with a copolyester hot-melt adhesive (Griltex® 9E from Company EMS-Griltech, Domat/Ems, Switzerland) on basis of modified polybutyleneterephthalate having a melting point of 119° C. by means of a powder dot coating. Thereby, the polyester face fabric was bonded to the hot-melt adhesive side of the film laminate. The copolyester hot-melt adhesive was applied in the powder fraction 80-200 μM and with a coating weight of 12 g/m 2 on the face fabric and sintered. The bond to the film laminate was carried out on a Meyer press at 135° C., a pressure of 5 N/cm 2 and a residence time of 12 seconds. EXAMPLE 6 [0050] For comparison, a commercial polyester face fabric and a commercial film Sympatex® (mark of the Sympatex-Technologies) were bonded with a copolyester hot-melt adhesive (Griltex® 9E from Company EMS-Griltech, Domat/Ems, Switzerland) by means of a powder dot coating. The copolyester hot-melt adhesive was applied in the powder fraction 80-200 μm and with a coating weight of 12 g/m 2 on the face fabric and sintered. The bond was carried out on a Meyer press at 135° C., a pressure of 5 N/cm 2 and a residence time of 12 seconds. EXAMPLE 7 [0051] The original adhesion of the laminated fabric of the Examples 4-6 as well as the adhesion upon washing for 5 times at 60° C. were measured. Additionally, the permeability to water vapour according to ASTM E-96-66 was determined before and after washing. [0052] Five cm wide textile laminates were clamped in a draw machine to measure the adhesive force. The test parameter was constant for all measurements. test velocity 100 mm/min width of specimen 50 mm test length 80 mm preload ON test temperature 25° C. [0053] The results are represented in Table 1. TABLE 1 comparison Example 4 Example 5 example 6 Original adhesion >12 >12 >12 [N/5 cm] (tear of (tear of (tear of substrate) substrate) substrate) Adhesion after >12 >12 delamination washing for 5× at 60° C. (tear of (tear of [N/5 cm] substrate) substrate) permeability 2731 2699 2745 to water vapour [g/m 2 in 24 h] permeability 2517 2509 delamination to water vapour after washing for 5× at 60° C. [g/m 2 in 24 h] [0054] While the invention has been disclosed in the patent application by reference to the details of preferred embodiments of the invention, it is to be understood that the disclosure is intended in an illustrative rather than a limiting sense as it is contemplated that modifications will readily occur to those skilled in the art within the spirit of the invention and the scope of the appended claims.	The invention relates to a method for production of a wash-resistant bond between a film on basis of copolyetherester waterproof and permeable to water vapor and at least one substrate on basis of polyester which is a woven or knitted fabric to achieve a pure bonded fabric having good wash resistance at 60° C., wherein said film on basis of copolyetherester which is waterproof and permeable to water vapor is manufactured with at least one film of a hot-melt adhesive on basis of a hydrophilic copolyetherester to a laminate previously before being bonded to said substrate by means of a hot-melt adhesive on basis of copolyester.	8
CROSS-REFERENCE TO RELATED APPLICATION This invention was made with Government support under contract No. DASG60-C-0038 awarded by the Department of the Army, Ballistic Missile Defense Systems Command. The Government has certain rights in this invention. This application is closely related to a commonly assigned application, Ser. No. 536,466, filed on Sept. 27, 1983 Syed Akbar and entitled "Multi-Master Communication Bus." BACKGROUND OF THE INVENTION This invention relates generally to communication networks comprising interconnected computers and other devices. More particularly, the invention relates to local-area networks in which a number of communication stations or nodes are connected to a common communication bus. Networks of this general type for the interconnection of computers and other devices are becoming increasingly common. The principal objective in designing such a network is to provde a convenient way for the separate devices or nodes to transmit messages and information from one to another. Instead of having to provide costly interconnections between all possible pairs of the devices, a single communication bus is employed. When one device has information to send to another, a message is transmitted onto the bus, and is read by the device to which the message is intended to be transmitted. One major task in designing a network of this type is to establish a scheme for resolving conflicts for the use of the bus. In this regard, there are two main types of network designs. One is what is commonly referred to as a contention scheme, in which conflicts for use of the bus are resolved at the time they arise, in accordance with a fixed set of priorities. If two nodes on the bus attempt to transmit at practically the same time, priority may be determined, for example, by the physical locations of the nodes, such that the node nearest one end of the bus is the first to transmit. One well known network system of the contention type is known by the name Ethernet, and is described in U.S. Pat. No. 4,063,220 to Metcalfe et al. The other major type of network uses some form of time slot allocation scheme, wherein each of the nodes is assigned a time slot in which it may transmit on the bus. These are all basically time-division multiplexing schemes. In the simplest form of time slot allocation scheme, the node allocations are fixed, and the system may be very inefficient when not all of the nodes are equally busy. If the time slots are dynamically allocated, there is still a priority problem to be resolved. In the past, a system of fixed priorities based on some physical parameter has been the usual approach to resolving this difficulty. Another important factor that has often dictated against the choice of a time slot allocation scheme is that some form of synchronization of the nodes is required, to make sure that each node can determine its proper time slot for transmission of data. This has necessitated the use of a master station at some location on the bus, to generate appropriate timing signals for use by the other nodes, which become, in effect, "slave" units. Reliance on a master station poses obvious reliability problems, since the integrity of the entire network then depends on a single master station. It will be appreciated from the foregoing that there is a need for a local-area network that both avoids the use of fixed priorities for bus access, and avoids the use of a single master station for purposes of synchronization. The present invention fulfills this need. SUMMARY OF THE INVENTION The present invention resides in a multimaster communication bus system in which none of the connected nodes functions as a single master station, and arbitration among multiple requests for bus access is performed prior to message transmission by a novel parallel arbitration scheme. As in the invention described and claimed in the cross-referenced application, timing and sequencing of message transmissions is a function that is distributed among all of the active nodes connected to the bus, so that one may consider all of the nodes to be master stations. In simple terms, the bus system of the invention employs a data bus and an arbitration bus, and includes, at each node, multi-master bus control logic for performing all timing functions, and for determining priority of bus access in a parallel fashion, i.e. at the same time as all of the nodes on the bus. More specifically, the multi-master bus control logic includes means for transmitting synchronization signals over the arbitration bus to maintain system synchronization, means for determining and transmitting a relative node priority if bus access has been requested, means for receiving from the arbitration bus a composite node number that is a logical combination of all of the transmitted relative node priorities, and means for comparing the composite node number with the transmitted relative node number to determine whether this node will be the next to transmit a message. The basic inventive concept is independent of the nature of the source and destination of the data messages. There may, for example, be a computing device located at each node. When the computing device has a message to transmit, it makes a bus request to the multi-master bus control logic, which then obtains access to the bus and signals the computing device that transmission may begin, or that it may begin as soon as a current transmission has ended. Access to the bus is granted on a round-robin basis, with each node having equal chance to transmit as soon as its turn comes up. In the round-robin scheme, a node that has just completed transmission has the lowest priority for the next message transmission. The nodes are each given an access opportunity in turn, beginning with one adjacent to the one that was last granted bus access, and ending with the one that was last granted bus access. If a node has a number of message transmissions to make, it may obtain repeated access to the bus, until such time as another node requests the bus. Then, the first node will have to relinquish the bus, at least temporarily. If the message traffic is relatively heavy and is generated uniformly by all the nodes, the nodes will share access to the bus on a round-robin basis, without preference for any particular bus. In the illustrative embodiment of the invention, the means for determining and transmitting the relative node priority includes means for computing the difference between the node number of the last node to send a message and the node number of the local node, and means for transmitting the resultant difference onto the arbitration bus, which includes means for logically ORing all of the the transmitted relative node priorities to obtain the composite node number. The means for comparing the composite node number with the locally generated relative node priority includes a bit-by-bit ripple comparison circuit, having means for successively comparing corresponding bits in the two node numbers, means for withdrawing the node from contention if there is no match between any compared bits, and means for generating a bus grant signal if all of the bits are found to match. The arbitration control logic also includes timing means for generating timing signals to control the arbitration sequence. In accordance with the method of the invention, arbitration among conflicting requests are resolved in a parallel fashion at all of the nodes. More specifically, the method comprises the steps of storing the number of the last node to send a data transmission; computing, in response to a bus request signal, a relative node priority, by determining the difference between the number of the last node to transmit and the the local node number; asserting the relative node priority onto the arbitration bus; generating on the bus a composite node number from all of the asserted relative node priorities; and detecting the composite node number on the bus. The next and most important step in determining priority is to perform a bit-by-bit comparison between the detected composite node number and the locally computed relative node priority. If there is a non-match at any bit stage, the relative node priority is no longer asserted onto the bus and the node is withdrawn from contention for bus access. The composite node number is then regenerated. If all bits are found to match, a bus grant signal is generated and a message transmission may begin. Additional steps in the method include asserting onto the arbitration bus the physical node number of the node being granted bus access, then latching this node number into a register at each node, to store the number of the last node to transmit. This latched node number is periodically asserted and relatched by all nodes, to ensure that all nodes are registering the correct last node number. It will be appreciated from the foregoing that the present invention represents a significant advance in the field of communication buses for local-area networks. In particular, the invention provides a single-bus communication system in which multiple nodes have equal access to the bus without the need for a central or master station to maintain synchronism, and in which arbitration between contenders for access to the bus is performed in a reliable and rapid parallel fashion prior to data transmission, again without a central or master control station. These and other aspects of the invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified block diagram of a multi-master bus communication system embodying the present invention; FIG. 2 is block diagram of the multi-master bus control logic of the invention; FIG. 3 is a timing diagram showing typical relationships between various signals on the arbitration bus and the information or data bus; FIG. 4 is a schematic diagram including the bit-by-bit ripple comparison circuit employed in the multi-master bus control logic of FIG. 2; and FIG. 5 is a flowchart illustrating the functions performed by the arbitration control logic of FIG. 2. DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the present invention is concerned with communication networks or computer networks in which multiple communication nodes are connected to a single data communication bus, indicated by reference numeral 10 in FIG. 1. A typical network includes a plurality of host devices, two of which are shown at 12 in FIG. 1, each having associated with it transmit/receive logic 14. Each host device 12 may be a computer, for example, but in general may be any source or destination of data. Each host device 12 communicates with its transmit/receive logic 14 over lines 16 and 18, and the transmit/receive logic 14 communicates with the data bus 10 over the bidirectional line 20. The specific design of the transmit/receive logic 14 will depend largely upon the nature of the host device 12, and does not form part of the invention. Ideally, in most applications a communication network should provide each node with an equal opportunity to access the bus 10. In the past, equality of access opportunity has been provided only at the expense of a master timing unit to ensure that the nodes are properly synchronized. In accordance with the invention, the system includes an arbitration bus 22 parallel to the data bus 10, and each host device 12 has associated with it multi-master bus control logic 24, whose function is to arbitrate in a parallel fashion among contending users of the bus 10 prior to each message transmission, and to synchronize bus operations without the use of a master station or central controller. The multi-master bus control logic 24 communicates with the arbitration bus 22 over bidirectional lines 26. When the transmit/receive logic 14 is ready to transmit a message on the data bus 10, a bus request is sent to the multi-master bus (MMB) control logic 24, as indicated by line 28. When access to the data bus 10 has been obtained, the transmit/receive logic 14 is informed by a signal on line 30. The MMB control logic 24 also receives a power-up reset signal from the transmit/receive logic 14, over line 32, to indicate that the node has just been powered up or reset for some other reason. FIG. 2 illustrates the MMB control logic 24 in more detail. Its principal components are a state sequencer circuit 40, an arbitration sync generator 42, an adder 44, a bit-by-bit ripple comparison circuit 46, a register 48 for storing the local or "my" node number, and a latch 50 for storing a reference node number that indicates the number of the last node to be granted access to the data bus 10. The state sequencer 40 is basically a timer or counter that is driven by high-frequency clock signals over line 52 from a clock signal generator (not shown), and is synchronized to arbitration sync signals generated by the synch generator 42 and coupled to the state sequencer over line 54. The sequence 40 generates a sequence of timing signals indicated by E1 through E5. These signals control initiation of an arbitration sequence, and related activity on the arbitration bus 22. The arbitration sync generator 42 detects a sync signal on one line 22a of the arbitration bus 22, receiving the signals through an inverter 56, and generates arbitration sync signals for transmission through another inverter 58 onto the line 22a. The sync signal is basically a square wave like the one shown at 60 in FIG. 3, and is generated continuously if there is at least one active node on the bus. The sync generator 42 may be of any conventional design, and may, for example, include a digital phase-locked loop. When power is first applied to the node, a signal on line 32 initiates operation of the sync generator, which monitors the bus sync line 22a for a composite sync signal, and synchronizes a generated sync signal with the composite sync signal on the bus line. Operation of the state sequencer 40 is keyed to the falling edge of the sync signal, as conveyed to the sequencer over line 54. The falling edge of the sync signal corresponds to the timing signal E5. The signal E1 is generated a predetermined time interval later, but only if a bus request signal has been received over line 28, and E1 initiates the arbitration sequence, to be described in detail. The signal E2 is generated at the same time as the next rising edge of the sync signal, but only if E1 was generated and if this node was selected to be the next one to acceess the bus, i.e. a bus grant signal was generated on line 30. Likewise, timing signal E3 is generated subsequently to E2 only if a bus grant signal has been generated. Timing signal E4 is generated close after E3, and E5 follows when the sync signal 60 falls again. Signals E4 and E5 are generated in every sync pulse cycle, regardless of whether a bus request is made or granted. The hardware that performs the arbitration sequence will first be described with reference to FIG. 2, although its mode of operation may not beome clear until a specific example, involving multiple nodes, has been considered. Arbitration comprises three distinct but closely related operations. First, if a bus request has been made, a relative node priority is computed and asserted on the arbitration priority bus 22b, which consists of enough binary signal lines to code the largest node number in the system. Next, the priority bus 22b generates a composite node number derived from all of the relative node priorities asserted on it. In logical terms the composite node number is the logical OR of the asserted relative node priorities. The final operation is a bit-by-bit comparison between the composite node on the bus 22b and the locally generated relative node priority. When a non-matching bit is found, the node is automatically withdrawn from contention for bus access and the composite node number may change accordingly. Ultimately, only one of the contending nodes will survive the bit-by-bit comparison, and a pass signal will be generated by the comparison circuit 46, on line 62. It will be appreciated from the more detailed description that follows that the three operations described are very closely related, and in some respects overlap. However, the simplified block diagram of FIG. 2 will facilitate a basic understanding of the arbitration sequence. More specifically, the relative node priority is determined by computing the difference between the local node number stored in register 48 and the number of the last node to transmit, stored in latch 50. As illustrated in FIG. 2, the last node number, or reference node number, is subtracted from the local node number. However, the subtraction may be performed in the opposite sense without affecting the inventive concept. The only effect of the opposite subtraction would be that priority would be rotated in the opposite cyclic direction. The subtraction is performed by complementing or inverting the reference node number in inverter 64 and applying the local node number as a non-inverted input to the adder 44. To provide subtraction in a two's complement sense, a logical "1" carry bit is input to the adder, as shown at 66. As will become apparent from a specific example, the output of the adder 44 provides a direct measure of relative priority on a round-robin basis. The highest priority will be given to a node immediately adjacent in number to the one that most recently gained bus access. The next highest priority will be adjacent in node number to the highest, and so forth. The lowest priority node will be the one that has most recently gained bus access. The relative node priority is transferred to the bit-by-bit comparison circuit 46 over line 68, and is coupled through the comparison circuit and over line 70 to an inverting gate 72, and thence to the arbitration priority lines 22b. The gate 72 is enabled by the presence of two signals, which are ANDed together in AND gate 74. One is the E1 timing signal from the state sequencer 40, and the other is an inverted FAIL signal derived from a non-inverted FAIL signal on line 76 from the comparison circuit 46. Thus, when the E1 timing signal is supplied to initiate argitration, and so long as there has been no failed bit comparison in the comparison circuit 46, the relatively node priority will be asserted on the bus 22b in inverted form. Each line of the priority bus 22b employs negative logic, in which a high signal represents a logical "0" and a now signal level represents a logical "1". Basically, each line of the bus 22b operates as a wired logical OR device. If a logical "1" is asserted on a line of the bus 22b by any node, the bus will stay at its low, logical "1" level regardless of the assertion of any logical "0" signals by other nodes on the bus. In effect, then, the bus will carry a composite node number that is the logical OR of all of the asserted relative node priorities. The inverted form of the composite node number is read back into the comparison circuit 46 through amplifier 78 and over line 80, for comparison with the locally generated relative node priority on line 68. Operation of the comparison circuit 46 will be described in detail with reference to FIG. 4. For present purposes, it need only be understood that the comparison circuit 46 will either generate a FAIL signal on line 76 or a PASS signal on line 62. If a FAIL signal is generated, the inverted form of this signal no longer enables AND gate 74, and the relative node priority is no longer asserted on the arbitration bus 22b. In effect, the node has dropped itself from contention for bus access. On the other hand, if a PASS signal is generated, the state sequencer 40 responds by generating a bus grant signal on line 30 and by generating an E2 timing signal. The E2 timing signal enables a gate 82, through which the local node number stored in register 48 is gated onto the arbitration priority bus. The purpose of this step is to provide to every node the identity of the "winning" node in the arbitration sequence. At a subsequent time in the sync signal cycle, an E3 signal is generated, to clock the latch 50 used to store the reference node number. Thus, upon the occurrence of timing signal E3, a new reference node number is clocked into the latch 50. Almost immediately after E3, timing signal E4 is generated. This enables another gate 84, through which the reference node number stored in latch 50 is gated onto the priority bus 22b. Still later, when the sync signal falls, timing signal E5 is generated to clock the latch 50 again, and load it with the node number presently asserted on the bus. The foregoing timing relationships are illustrated diagrammatically in FIG. 3. As indicated at 90, a message is being transmitted on the information bus 10 prior to the exemplary arbitration sequence. Then, as indicated at 92, the current reference node is "echoed" to all nodes on the bus. Timing signal E4 asserts the reference node number on the bus at each node, and timing signal E5 clocks the asserted reference node number into the latch 50 at each node. The next significant event is the generation of an E1 timing signal, resulting from a bus request. During the period indicated at 94, arbitration among competing nodes is performed in the manner described above. In the winning node, E2 and E3 timing signals are generated after the arbitration sequence, and the number of the winning node is transmitted to the bus and latched at each node. This activity is indicated by reference numeral 96. At this point, a new message transmission can begin, as indicated at 100. Then, timing signals E4 and E5 again result in the echoing of the reference node number by and to all nodes, as indicated at 102. As indicated in the timing diagram of FIG. 3, arbitration in the presently preferred embodiment of the invention is not started until the completion of a prior message. Since arbitration is so fast, less than a microsecond, no significant inefficiency is introduced by performing arbitration during an inter-message gap. However, there is nothing inherent to the invention that imposes this limitation. Since the arbitration bus 22 is completely separate from the data bus 10, the arbitration could be performed while a message was still being transmitted, and the bus grant signal then made conditional on there being a cessation of bus activity. Before proceeding to a further description of the arbitration sequence, it is appropriate to consider a specific example of arbitration. The example in Table 1 assumes that the reference node number is 3 (00011 binary), and that the arbitration priority bus 22b has five lines, to accommodate five-bit node numbers. TABLE 1______________________________________ Bit 4 Bit 3 Bit 2 Bit 1Rel. com- com- com- com- Bit 0Prty. pare pare pare pare compare______________________________________Node #4 00001 Fail -- -- -- --3 00000 Fail -- -- -- --1 11110 Pass Pass Pass Pass Win bus0 11101 Pass Pass Pass Fail --29 11010 Pass Pass Fail -- --Compos.Node # 11111 11111 11111 11111 11110 11110______________________________________ The computation of the relative node priorities is made using two's complement arithmetic. For example, the result for node #4 is obtained by inverting the reference node number, giving 11100, then adding the local node number 00100 and the constant carry of 00001. The result, ignoring overflow, is 00001, which might have been expected from he decimal equivalent: 4-3=1. By a similar process, the relative priority for node #3 is zero. For node numbers less than the reference node number, the result is not always so obvious. For the winning node, node #1, the relative priority is determined by adding the complement of three, or 11100, to 00001 and the carry input of 00001. The result is 11110, or 30 in decimal terms. If one were to consider all the nodes from #0 to #31, the relative priorities would start at #0 for the reference node, #1 for the node number one greater than the reference node, and so forth up to node #31, whose relative priority is (31--reference node #). Then, node #0 has a relative priority one greater than that of node #31, and so forth up to a relative priority of #31 for the node with a number one less than that of the reference node. The effect of the bit-by-bit comparison is to choose the contending node with the greatest relative node number. In the example of Table 1, if node #2 had requested the bus it would have received the grant, since its relative node number is the sum of 00010, 11100 and 00001, which is 11111, or 31 decimal. FIG. 5 shows operation of the MMB control logic at each node in flowchart form. When power is first applied to the node, as shown at 110, the state sequencer is free-running and not yet synchronized to anything, as indicated at 112. As described in blocks 114 and 116, the sync generator 42 monitors the bus for any composite sync signals that are already present, and asserts its own sync signal onto the bus in synchronism with the composite signals. The next step, in block 118, is to sychronize the state sequencer 40 with the composite sync signals on the bus. The remaining initialization step, shown in block 120, is to read the arbitration bus into the reference node number latch 50, using timing signal E5. Then, if there is a bus request at this node, as determined in block 122, the relative node priority is calculated, as indicated in block 124, and asserted onto the bus, as shown in block 126. In block 128, the composite node number is read from the bus, and in block 130 is compared with the locally generated relative node priority. If there is a complete match, the local node number is asserted on the bus, as shown in block 132, and message transmission is started, as indicated in block 134. If there is no match in the comparison of block 130, the next two steps in blocks 132 and 134 are skipped, and in block 136 the number of the acquiring node is latched. Finally, as indicated in blocks 138 and 140, the number of the reference node, or the last acquiring node, is echoed onto the bus by all nodes, and subsequently latched again at all nodes. Then a return is made to block 122 to determine if there is a bus request. In the present embodiment of the invention, node arbitration is conditioned not only on receiving a bus request, but also on there being no present activity on the data bus 10. If the test for a bus request in block 122 has a negative result, there is an additional test to determine if the arbitration bus is active, as indicated in block 142. If it is, the arbitration steps are skipped, and control is transferred to the step of latching the acquiring node number, in block 136. If the arbitration bus is not active, no node is currently requesting the bus, and control is transferred to block 138, to echo the reference node onto the bus. The bit-by-bit ripple comparison circuit 46 is shown in more detail in FIG. 4. The circuit includes five identical comparison blocks 150-154 and five corresponding NAND gates 155-159. Each of the comparison blocks has a relative node input (RI), a relative node output (RO), an inverted bus input (BI), an enable input (EN), and a pass/fail output (P/F). As shown, each comparison block 150-154 includes an OR gate 160, and two AND gates 162 and 164. The OR gate 160 has as inputs the signals RI and BI, and provides its output as one input to AND gate 162. The other input to AND gate 162 is the enable signal EN, and the output is the pass/fail signal P/F. The relative node priority input RI is also applied to the other AND gate 164, which also receives as its second input the enable signal EN. The output of AND gate 164 is the relative node priority output signal RO. The relative node priority output signals RO from each of the comparison blocks 150-154 is applied as an input to a respective one of the NAND gates 155-159. The other input of each NAND gate 155-159 is the timing signal E1 employed to enable the arbitration sequence. The outputs of the NAND gates 155-159 are applied to the arbitration priority bus 22b. The five bus signals are also fed back through respective amplifiers 166-170 to the BI inputs of the comparison blocks 150-154/ In each of the comparison blocks 150-154, there are only three possible logical combinations: (a) the relative node priority is a "1" and the bus also supplies a "1", (b) the relative node priority is a "0" and the bus supplies a "0" because no other node has asserted a "1", and (c) the relative node priority is a "0" and the bus supplies a "1" because another node has asserted a "1". Because of the logical OR action of the bus, it is impossible for the bus to supply a "0" if the relative node priority asserts a "1". Case (a) is the simplest. In the first-stage comparison block 150, if RI is a "1" OR gate 160 has its output enabled, and if there is a bus request signal to enable AND gate 162, there will be a "1" signal on the P/F line from the comparison block. This line is fed to the enable line EN of the next comparison block 151, which enables the next stage of the comparison. In case (b), a "0" is input on line RI, which will therefore not enable an output from OR gate 160. However, the "0" level on output RO is inverted in NAND gate 155 and is encoded as a "1" in the bus's negative logic. Thus, input BI is a "1", which is propagated through OR gate 160 and AND gate 162 to the P/F output line to the next stage. Finally, in case (c) a "1" asserted onto the bus by another node's relative priority shows up as a "0" at the BI input to the comparison block. If the RI input is also a "0", the output of OR gate T60 and AND gate 162 will also be "0" and an enable signal will not be propagated to the next stage. If a pass signal is not generated at any stage, the next stage is not enabled and the node is effectively removed from contention. The enable lines EN of all but the first comparison block 150 are, therefore, equivalent in function to the FAIL line 76 in FIG. 2. If the final stage comparison block 154 passes the test, a "1" is output on the PASS signal line 62 to the state sequencer 40, which is thereby conditioned to output an E2 timing signal and a subsequent E3 timing signal, to transmit the acquiring node number to all nodes. It will be appreciated from the foregoing that the present invention represents a significant advance in the field of communication networks having multiple nodes connected to a common bus. In particular, the invention provides a novel technique for arbitrating among competing requests for bus access, without any central or master node unit. 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 is not to be limited except as by the appended claims.	Apparatus and a related method for regulating access to a communication bus to which multiple communication nodes are connected. Control logic at each of the nodes determines which of them has priority to access the bus, by means of a parallel arbitration sequence in which all nodes contending for bus access participate. Specifically, each contending node generates a relative priority node number and asserts it onto an arbitration bus. All of the asserted node numbers are logically combined into a composite node number on the bus, and the winning node is determined in a bit-by-bit ripple comparison circuit at each node, the composite node number being compared with the locally generated relative priority node number. Priority is determined in advance of data transmission, and synchronization and arbitration take place without any central or master control unit.	6
This application is a continuation of application Ser. No. 08/504,897, filed on Jul. 20, 1995, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to methods for installing barge bumper systems, otherwise known as fendering systems, on offshore platforms, and in particular to a method for retrofitting a fendering system to an offshore platform wherein the fendering system is installed as a one piece unit without the need for construction of a cofferdam. 2. Description of the Related Art During their construction and throughout their working lifetimes, offshore platforms require a certain level of sea traffic. Service vessels and barges routinely ferry equipment, supplies, and other necessities to and from the platforms. Depending upon the sea and weather conditions, and the skill of the vessel pilot, the docking of these vessels can result in potentially damaging collisions to the platform legs. There is also the ongoing risk of accidental collisions. Accordingly, protecting offshore platforms from potentially damaging collisions is desirable. For a number of years fendering system systems have been used on offshore platforms to dampen the impact energy transmitted from a vessel to the platform legs during collisions. The fendering system systems have historically consisted of some type of vertically disposed elongated contact post or bumper that is coupled to the platform leg by one or more load cells. The load cells typically contain some type of elastomeric member that acts as a shock absorber. The vertically disposed bumper prevents an approaching vessel from directly impacting the platform leg and will absorb the impact energy of a collision with the vessel, transmitting the energy therefrom into the load cells where the majority of the energy is transformed from kinetic energy to, and stored as, potential energy. The transformation of kinetic energy to potential energy reduces the reaction force on the platform leg and impacting vessel thereby minimizing damage to both. For a variety of reasons, offshore fendering system systems have historically had finite life spans. Accidental collisions, ordinary impacts, wave action, metal corrosion, and degradation of the elastomeric components in the load cells lead to an eventual failure of the offshore fendering system. When the fendering system systems fail, the platform cannot be towed to land for installation of new fendering systems. Consequently, the replacement must be done at sea. Historically, the replacement of an offshore boat fender system has required sophisticated and costly retrofit procedures. A number of factors contribute to the cost and complexity of current retrofit procedures. First, most offshore fendering systems are ordinarily installed on the platform legs component by component before the platform is transported to its final destination offshore. As a consequence, the current methods of replacing an existing fendering system typically calls for the construction of a cofferdam around the submerged fendering system to facilitate the installation of numerous components in a relatively water and wave free environment. A cofferdam may also be necessary if undersea welding operations are necessary. Second, the configuration of most offshore platforms makes most offshore fendering systems inaccessible to cranes positioned on the platform deck. Consequently, the cofferdam construction, existing fendering system demolition, and new fendering system installation depend almost exclusively on a support vessel crane for lifting capability. In high seas, the ability of the support vessel to facilitate the cofferdam installation and fendering system demolition and installation may be hampered, and large swells may wash water into the cofferdam making it difficult to maintain a dry work environment. The present invention is intended to overcome or minimize one or more of the foregoing disadvantages. SUMMARY OF THE INVENTION In one aspect of the present invention, a method is provided for removing an existing fendering system from a leg of an offshore platform and replacing it with a new fendering system with the assistance of a support vessel equipped with a crane. According to the method, a jib crane is coupled to the leg above the existing fendering system. The jib crane has a lifting cable. A first upper load cell of the existing fendering system is detached from the leg. The first upper load cell is attached to the leg at a first preselected position. A first lower load cell of the existing fendering system is detached from the leg. The first lower load cell is attached to the leg at a second preselected position. By means of the crane, the existing fendering is removed. By means of the crane, the new fendering system is placed proximate the leg. The new fendering system includes an elongated cylindrical bumper, a second upper load cell coupled to the bumper, and a second lower load cell coupled to the bumper in spaced relation to the second upper load cell. By means of the jib crane, the new fendering system is raised to position the second upper load cell at the first preselected position and to position the second lower load cell at the second preselected position. The second upper load cell and the second lower load cell are then coupled to the leg. In another aspect of the present invention, a jib crane adapted to be coupled to a leg of an offshore platform for replacement or maintenance of an existing fendering system is provided. The jib crane includes a generally horizontally disposed boom pivotally coupled to the leg such that the boom is operable to selectively pivot in a horizontal plane. A hoist is rollably coupled to the boom. The hoist has a vertically moveable hook that is operable to lift objects. The hoist is operable to translate along the boom. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: FIG. 1 illustrates a side view of an existing fendering system; FIG. 1A illustrates a top view of the arrangement of FIG. 1; FIG. 2 illustrates a side view of an existing fendering system, showing the installation of a jib crane; FIG. 3 illustrates a pictorial view of the jib crane; FIG. 4 illustrates a partial sectional view of the jib crane of FIG. 3, taken at A--A; FIG. 5 illustrates an alternate embodiment of the jib crane of FIG. 3; FIG. 6 illustrates a side view of an existing fendering system upon removal from the platform leg; FIG. 7 illustrates a pictorial view of the stub and a portion of the platform leg following preparation of the stub for installation of a new fendering system; FIG. 8 illustrates a side view of the initial positioning of a new fendering system; FIG. 9 illustrates a side view of a new fendering system installed on a platform leg; FIG. 10 illustrates a sectional view of FIG. 9, taken at section A--A; FIG. 11 illustrates a sectional of FIG. 9, taken at section B--B; FIG. 12 illustrates a side view of the coupling of the upper and lower load cells of the new fendering system to the platform leg; and FIG. 13 illustrates a side view of completed installation of the new fendering system. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and, in particular to FIG. 1, there is shown an existing fendering system 10 that is coupled to one leg 12 of an offshore platform 13. It should be understood that a typical offshore platform has four or more of such legs 12 and, accordingly, a complimentary number of existing fendering systems 10. However, for simplicity of illustration replacement of only one existing fendering system 10 is discussed. The leg has a relatively vertically disposed upper portion 14 and an angularly disposed lower section 16. The upper end of the lower section 16 is connected to a spider deck 18 on the platform (not shown). In FIG. 1 and where applicable in the other figures, the mean water line is indicated at 17. The existing fendering system includes an upper load cell 20 coupled to the upper end of the lower leg 16 and a lower load cell 22 coupled to the lower end of the lower section 16. The upper load cell 20 is typically an elongated cylindrical member that is typically welded to the upper end of the lower section 16 at 24. The lower load cell 22 is also a generally cylindrical member that may be either welded to the lower end of the lower section 16 or, as shown in FIG. 1, or attached to the lower end of the lower section 16 by a bolted clamp 26. The structure and function of the upper and lower load cells 20 and 22 will be described in more detail below. A relatively vertically disposed bumper 28 is coupled at its upper end 30 to the upper load cell 20 and at its lower end 32 to the lower load cell 22. The bumper 28 is a generally cylindrical elongated tubular member that may or may not contain an elongated cylindrical elastomeric member (not shown) as discussed more fully below. FIG. 1 shows a partial stern view of a typical support vessel 34 and a support barge 36 anchored next to the existing fendering system 10. FIG. 1A shows a top view of the arrangement of FIG. 1. The support vessel 34 has a lifting crane 38 fixed to its deck. A jib crane 40, the structure and function of which will be described more fully below, is temporarily disposed on the support barge 36. It should be understood that the retrofit operation may be carried out with a single vessel that is equipped with a crane and that is large enough to transport the existing fendering system 10. The removal of the existing fendering system is illustrated in FIGS. 2-6, inclusive. FIG. 2 depicts the leg 12 and existing fendering system 10 disposed below a typical upper deck 42 of the platform 13. The first step in retrofitting the platform 13 with a new fendering system is to remove the existing fendering system 10. The portable jib crane 40 is lifted from the deck of the support barge 36 by the crane 38 to an elevated position where it is coupled to a winch 44 that is disposed on the upper deck 42. The jib crane 40 is attached to the winch 44 by a cable 46 that extends down through the upper deck 42. The jib crane 40 is temporarily held in an elevated position proximate the upper end of the upper section 14. A tag line 48 is slung around the cable 46 to provide for azimuth adjustments of the jib crane 40. A lower stop 50 for the jib crane 40 is weld or otherwise coupled to the exterior of the upper section 14 of the leg 12. The stop 50, depicted in FIG. 2 as a pair of lugs welded to the exterior of the upper section 14 of the leg 12, is designed to define the lower limit of vertical movement of the jib crane 40, and accordingly may be any of a variety of shaped members that protrude outward from the exterior of the upper section 14 of the leg 12. The jib crane 40 provides a significant lifting capability that is independent of the platform cranes and the effects of wave action that may hamper the support vessel crane 38. Referring now also to FIGS. 3 and 4, which are, respectively, a pictorial view of the jib crane 40 just prior to installation on the upper section 14 of the leg 12 (shown in phantom) and a partial sectional view of FIG. 3 taken at section A--A, the jib crane 40 includes a horizontally disposed boom 52, a motorized hoist 54 rollably disposed on the boom 52, and a three piece cylindrical clamp 56 that is designed to secure about the upper section 14 of the leg 12. The inboard end 58 of the boom 52 is pivotally coupled to a cantilever member 60, that is, in turn, coupled to the three piece clamp 56. The pivotal coupling between the cantilever member 60 and the inboard end 58 of the boom 52 consists of a tongue and fork connection. A fork 62 is welded or otherwise connected to the boom 52. A tongue 64 is welded or otherwise connected to the cantilever member 60. The tongue 64 is disposed within the fork and pivotally held in place therein by a vertically disposed pivot pin 66 that is journaled through concentric openings 68 and 70 in the fork 62 and 72 in the tongue 64. The pivot pin 66 has at its upper end a circular flange 74 that is larger in diameter than the opening 70 to prevent the pivot pin 66 from falling therethrough. A locking ring 76 is peripherally disposed around the lower end of the pivot pin 66 to prevent the pivot pin 66 from popping up through the openings 68, 70, and 72. When the jib crane 40 is in operation, the boom 52 will ordinarily be locked in the position shown in FIG. 3 by a locking pin 78 that is journaled through the tongue 64 and the pivot pin 66 and/or by a vertically disposed locking pin 80 that is journaled through the fork 62 and the cantilever member 60. Two or more triangular gussets 82 are welded into the end of the fork 62 that is coupled to the boom 52. The cantilevered member 60 is welded or otherwise connected to the three piece clamp 56 and supported thereon by one or more circumferentially spaced triangular gussets 84. The outboard end 86 of the boom 52 is connected to the upper section 14 of the leg 12 by a support chain 88. The support chain 88 is put into position and coupled to the upper section 14 and the outboard end 86 of the boom 52 after the jib crane 40 is clamped to the upper section 14. The boom 52 preferably has an I-beam construction such that the rollers 90 of the hoist 54 are rollably disposed in parallel channels 92 and 94. The hoist 54 is operable to both translate back and forth along the boom 52 as well as raise and lower a lifting cable 96. The rollers 90 and winch 44 may be powered either pneumatically, electrically, or hydraulically, or some combination thereof. A preferred hoist is an HA1 series manufactured by Ingersoll-Rand, or a similar hoist. FIG. 5 depicts an alternate preferred embodiment of the cantilevered member 60. In this preferred embodiment, the cantilevered member 60 is divided into an inboard portion 98 and an outboard portion 100. The inboard portion 98 is welded or otherwise connected at one end to the three piece clamp 56 and the other end terminates in a flange 102 adapted for bolt connection to an identical flange 104 on one end of the outboard portion 100. The inboard and outboard portions 98 and 100 are intended to be joined in a stabbing movement. To facilitate that stabbing movement, the flange 102 has a central inwardly tapering female opening 106 that is adapted to receive a tapered nipple 108 projecting away from the flange 104. Once the stabbing movement has occurred, the flanges 102 and 104 are bolt connected. In all other respects, the cantilevered member 60 is identical to the aforementioned embodiment. Referring now also to FIG. 6, which illustrates the removal of the existing fendering system 10, following installation of the jib crane 40, the hoist 54 is actuated to lower the lifting cable 96 down to the upper load cell 20. The lifting cable 96 is coupled to the upper load cell 20. In addition, the crane 38 on the support vessel 34 is coupled to the bumper 28 at one or more contact points 110. The lower load cell 22 is then disconnected from the lower section 16 of the leg 12. If the lower load cell 22 was coupled to the lower section 16 by a bolt clamp, this step will entail simply removing the bolts. If, however, the lower load cell 22 was welded to the lower section 16, the lower load cell 22 would have to be cut from the lower section 16. After the lower load cell 22 is removed from the lower section 16, the upper load cell is severed, by cutting torch or other cutting methods, from the upper end of the lower portion 16, leaving a portion of the upper load cell 20 as a generally hollow and cylindrical stub 112. To prepare the stub 112 for reception of a new fendering system, a fastening lug 114 is coupled to the outboard side edge of the stub 112. The lug 114 is typically a flange 116 with a hole 118 bored therethrough as shown in FIG. 7, which is a pictorial view of the stub 112. To facilitate coupling with the upper load cell of the new bumper system, a circular tapered surface 120 is cut in the interior of the rim 122 of the stub 112. The tapered surface 120 is shown highly exaggerated in FIG. 7. Referring now to FIGS. 8 and 9, following preparation of the stub 112, a new fendering system 124 is readied for installation. The new fendering system 124 is structurally similar to the existing fendering system 10 in that it includes a vertically disposed bumper 126 that has an upper load cell 128 coupled to its upper end and a lower load cell 130 coupled to its lower end. As discussed more fully below, the upper load cell 128 is adapted to be coupled to the stub 112, and the lower load cell 130 is adapted to be coupled directly to the lower section 16 of the leg 12 by a three piece bolt clamp 132. Because the upper and lower load cells 128 and 130 contain an elastomeric joint, there is the possibility that the upper and lower load cells may deflect downwards prior to coupling to the stub 112 and leg 12. This deflection may cause the misalignment of the load cells 128 and 130. To obviate the potential difficulty, a vertically disposed elongated stabilizer 133 is coupled to the lower side of the upper load cell 128 and the upper side of the lower load cell 130. Alternatively, the upper load cell 128 may be stabilized prior to coupling by one or more angularly disposed elongated members (not shown) that are coupled to the lower side of the upper load cell 128 and to the bumper 126. Similarly, the lower load cell 130 may be stabilized prior to coupling by one or more angularly disposed elongated members (not shown) that are coupled to the upper side of the lower load cell 130 and to the bumper 126. The exterior of all components of the new fendering system 124 are preferably coated with an epoxy coating system, such as the epoxy high system, manufactured by Ameron Protective Coatings, Inc. The detailed structure of the upper load cell 128 may be understand by reference to FIG. 10, which is a sectional view of the new fendering system 124 taken at section A--A. The upper load cell 128 includes a generally cylindrical housing 134 that encases an annularly shaped elastomeric member 136, the exterior of which is bonded to the interior of the cylindrical housing 134. A generally cylindrical plunger 138 is bonded at one end to the annular elastomeric member 136 and at its other end to a generally cylindrical elongated elastomeric member 140 disposed within the bumper 126. A bevelled annular attachment guide 142 is weld or otherwise coupled to the cylindrical housing 134. The bevelled annular attachment guide 142 is preferably formed from a portion of cylindrical pipe of a diameter slightly smaller than the interior diameter of the cylindrical housing 134 that is cut at an angle, not unlike the end of a hypodermic needle. The bevelled annular attachment guide 142 is coupled to the cylindrical housing 134 so that the bevelled end protrudes therefrom a sufficient amount to slide easily into the stub 112 to facilitate coupling between the upper load cell 128 and the stub 112. The precise angular orientation of the bevelled annular attachment guide 142 is not critical. The structure of the lower load cell 130 may be understood by reference to FIG. 11, which is a sectional view of FIG. 9 taken at section B--B. The lower load cell 130 includes a cylindrical housing 144 that is coupled at one end to the three piece clamp 132 and at its other end to a plunger 146 by an annular elastomeric member 148 that is encased within and bonded to the interior of the cylindrical housing 144. The plunger 146 is journaled through, and bonded to, the annular elastomeric member 148. The other end of the plunger 146 is bonded to another elastomeric member 149 that is substantially identical to the elastomeric member 140. After the new fendering system 124 and the stub 112 have been prepared for installation, the new fendering system is coupled to the jib crane 40 at the upper load cell 128 and to the support vessel crane 38 at the contact points 150. The jib crane 40 and the support vessel crane 38 are both lowered to lower the new fendering system 124 into the water. Once the new fendering system 124 is partially submerged, the support vessel crane 38 is detached from the contact points 150. The hoist 54 on the jib crane 40 then raises the new fendering system 124. Lateral adjustments to the new fendering system 124 may be made via tag lines 152 and 154, which are coupled to the bumper 126. The support vessel crane 138 may be used to aid azimuth positioning of the bumper 126. The hoist 54 on the jib crane 40 lifts the new fendering system 124 until the bevelled annular attachment guide 142 assumes a position that is nearly concentric with the stub 112. When a relatively concentric alignment is achieved, the jib crane 40 is moved laterally to stab the bevelled annular attachment guide 142 into the stub 112. The bevelled character of the bevelled annular attachment guide 142 combined with the circular tapered surface 120 on the stub 112 facilitates the stabbing movement. When the stabbing movement is complete, the end surfaces of the stub 112 and the cylindrical housing 134 should abut. After the stabbing movement, the flange 116 on the stub 112 should align with a substantially identical matching flange 156 on the cylindrical housing such that a pin 158 may be passed through both to temporarily secure the upper load cell 128 to the stub 112. Referring now also to FIG. 12, which illustrates the final securing of the new fendering system 124, after the pin 158 has been inserted, the tag line 154 is tensioned to draw the bolted clamp 132 into contact with the lower section 16. The three piece clamp 132 may then be clamped around the lower section 16 and securely bolted into position. After the lower load cell 130 is clamped to the lower section 16, a support chain 160 is coupled to the upper section 14 and the upper end of the bumper 26. The upper load cell 128 is then welded or otherwise permanently coupled to the stub 112. The stabilizer 133 is removed. The installation of the new fendering system 124 is now complete. The jib crane 40 is uncoupled from the upper load cell 128 and removed from the upper section 14 by reversing the steps described above for its installation. By means of the support vessel crane 38, the jib crane 40 and the stabilizer 133 are returned to the support barge 36 as shown in FIG. 13. Although a particular detailed embodiment of the apparatus has been described herein, it should be understood that the invention is not restricted to the details of the preferred embodiment, and many changes in design, configuration, and dimensions are possible without departing from the spirit and scope of the invention. For example, jib crane may be left on the leg 12 following installation of the new fender system 124.	A method of retrofitting an offshore platform fendering system includes the steps of installing a jib crane on a platform leg above the existing fendering system, detaching the upper and lower load cells from the leg, and removing the existing fendering system using the jib crane in concert with a support vessel crane. The upper load cell of the existing fendering system is detached to leave a protruding cylindrical stub. Using the jib crane and vessel crane, a new unitary fendering system is then positioned next to the leg. The upper load cell is coupled to the stub and the lower load cell is clamped to the leg. The new fendering system is installed as a unitary piece, that is, an elongated bumper with the upper and lower load cells already attached.	5
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a Continuation-in-Part Application of U.S. Ser. No. 11/254,844 filed Oct. 20, 2005 which is a Continuation-in-Part Application of U.S. Ser. No. 11/053,087 filed Feb. 8, 2005, which application is a non-provisional U.S. application, all of which are herein incorporated by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to heating and cooling. More particularly, but without limitation, the present invention relates to a complete plastic HVAC component system for distributing air and method for installing the same. [0003] A problem of common interest in heating and cooling is efficiency. Increasing the efficiency of a heating and cooling system results in decreased costs of operating the heating and cooling system. A key aspect contributing to the efficiency or inefficiency of a heating and cooling system is the heat and cooling losses incurred as air travels from the furnace through the ductwork and ultimately to the distribution points. [0004] Conventionally, the ductwork between the furnace and the distribution points have been formed of sheet metal. Ducts or pipes as well as fittings such as elbows, angles, couplers and boots are formed of riveted or welded sheet metal. Due to the nature in which these various parts are made there are often cracks in the ductwork and between the associated fittings that result in heating or cooling loss. Cracks can result in an undesirable whistling sound and provide an opening for insects to access the inside of the ductwork. [0005] In more recent times, flex pipe is replacing sheet metal ducts. Flex pipe is generally associated with less heat loss and is easier to handle than conventional sheet metal ductwork. [0006] Another problem relates to installation of ductwork. Metal ductwork often presents sharp edges and corners to work around to prevent injuries from resulting. [0007] A further problem relating to sheet metal ductwork is that it inherently collects dust and dirt on it's surface. In high humidity environments the surface of the sheet metal sweats collecting dust and dirt. A thin film of oil on the sheet metal's surface that is developed during manufacturing also collects unwanted dust and dirt particles during assembly and use. [0008] Another problem relating to installation and repair is inventory. Ductwork can be of various sizes, including ducts being of 6 inch diameter or 7 inch diameter. Corresponding fittings come in 6 inch or 7 inch diameter, although reducers are available. The difference in diameters of ductwork requires that those who stock ductwork to carry inventory for both dimensions. This can be of particular concern to those who install or replace ductwork as they either need to maintain a full inventory of parts. [0009] An additional problem relating to the use of sheet metal to form the ductwork and various components is the probability of incurring damage when dropped. Sheet metal components, ductwork and their connections risk becoming increasingly inefficient if dropped or subjected to excessive force during handling or installation. [0010] Therefore, it is a primary object, feature, or advantage of the present invention to improve upon the state of the art. [0011] It is a further object, feature, or advantage of the present invention to provide a complete plastic HVAC component system capable of efficiently delivering air from a furnace to distribution points having a limited number of fittings. [0012] It is a further object, feature, or advantage of the present invention to provide for a complete plastic HVAC component system having individual fittings capable of use with square and round ductwork. [0013] It is a further object, feature, or advantage of the present invention to provide for improved connections between a furnace, the ductwork and the registers to reduce losses and improve efficiency. [0014] Another object, feature, or advantage of the present invention is to provide plastic fittings that can be adapted to accommodate ductwork having different diameters. [0015] A further object, feature, or advantage of the present invention is to provide plastic fittings that reduce the amount of inventory needed. [0016] A still further object, feature, or advantage of the present invention is to eliminate sharp metal edges which can result in injury. [0017] Yet another object, feature, or advantage of the present invention is to provide fittings suitable for use with flex pipe. [0018] A still further object, feature, or advantage of the present invention is to provide fittings that are seamless and without cracks that leak air and allow insects access. [0019] Another object, feature, or advantage of the present invention is to provide fittings that are quiet and do not generate a whistling sound. [0020] Yet another object, feature, or advantage of the present invention is to provide fittings with a flange or lip to stabilize the fittings during installation. [0021] A further object, feature, or advantage of the present invention is to provide rigid fitting and/or flexible fittings that do not require an adapter to couple to different size piping. [0022] A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors resistant against damage during storing, handling and connecting. [0023] A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors resistant to sweating in high humidity environments. [0024] A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors resistant against dust, dirt and pollen collection during storing, handling and use. [0025] A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors and a method for installing the same. [0026] One or more of these and/or other objects, features, or advantages of the present invention become apparent from the specification and claims that follow. SUMMARY OF THE INVENTION [0027] The present invention provides a complete plastic HVAC component system for distributing air and method for installing the same. According to one aspect of the present invention, individual plastic components, of complimentary shapes and sizes, provide a system for creating ductwork to channel air from a central air unit to multiple distribution points. The individual plastic components include torpedo boots, register boots, straight boots, flexible joints, solid pipes, duct runners and end caps, couplers, 90-degree takeoffs and straight takeoffs. The boots, flexible joint, coupler, solid pipe, 90-degree and straight takeoffs are formed of a unitary body of plastic. The boots have a unitary body with a substantially circular first opening for connecting to a flexible joint, solid pipe or flexible pipe and a substantially rectangular second opening for connecting to a register. The unitary body of the boot defines an air pathway between the first opening and the second opening. The unitary body can be adapted for connection to either a flexible joint, solid pipe, coupler or flexible duct each having a first diameter or a second diameter. The solid pipe, coupler, flexible joint and flexible pipe each have a unitary body with a substantially circular first opening and second opening for connecting to each other, a boot or a duct runner. The unitary body of the solid pipe, coupler, flexible joint and flexible pipe defines an air pathway between the first opening and the second opening. The unitary body can be adapted for connection to each other, a boot, a top and a side takeoff each having a first diameter or a second diameter. The 90-degree takeoffs and straight takeoffs are formed of a unitary body of plastic. The takeoffs have a unitary body with a substantially circular first opening for connecting to a flexible joint, solid pipe or flexible pipe and a substantially rectangular second opening for connecting to a duct runner. The unitary body of the takeoffs defines an air pathway between the first opening and the second opening. The first opening can be adapted for connection to either a flexible joint, solid pipe, coupler or flexible duct of a first diameter or a second diameter. The duct runner is formed of a sheet of plastic with sufficient thickness to resist damage during assembly, storing or installation. The plastic sheet is scored along the length of the sheet to create a hinged profile and allow for folding. A preferable method of assembling the duct runner is completed by folding the plastic sheet along the scorings, creating a rectangle shape and siliconing and screwing the raised flange to the second connecting edge. Once assemble, the duct runner is a unitary body of plastic having a substantially rectangular first and second opening for connecting to another duct runner, plenum chamber or end cap. The duct runner can also be adapted for connection to a 90-degree takeoff and a straight takeoff. Preferrably, the torpedo boots, register boots, straight boots, flexible joints, solid pipes, duct runners and end caps, couplers, 90-degree takeoffs and straight takeoffs are made of a plastic material. [0028] According to another aspect of the present invention, a complete plastic HVAC component system for distributing air and providing a tight connection between ductwork and a ducted heating or cooling system and a register to prevent loss of air while providing for ease of installation is provided. The register, straight and torpedo boots include a unitary body formed of plastic for preventing the loss of air. The unitary body has a first opening for receiving air from the pipe. The unitary body has a second opening for passing air to the register. The second opening is of a substantially rectangular shape and adapted for connection to the register. The boots are adapted to be configured to fit pipe, whether 6 inch or 7 inch in diameter. The pipe is a unitary body having a raised flange on each end and form a tight connection when connected to each other, a coupler, a straight or a 90-degree takeoff. The pipe, whether flexible or rigid, can be connected to each other by removing one of the coupling collars from an end and inserting into the end of another pipe still having the coupling collars. The 6 and 7-inch pipe connect tightly with the 6 and 7-inch collar on any of the boots, couplers or takeoffs. The takeoffs are tightly secured to the duct over top of the opening formed in the duct wall for air passage. When assembled, the components provide an efficient guide for directing air from a central unit to multiple distribution points while preventing cooling and heating efficiency losses. BRIEF DESCRIPTION OF THE DRAWINGS [0029] FIG. 1 is a perspective view of a system for distributing air from a central air unit to various distribution points using complimentary plastic HVAC components. [0030] FIG. 2 illustrates a perspective view of one embodiment of a register boot of the present invention. [0031] FIG. 3 illustrates a perspective view of one embodiment of a torpedo boot of the present invention. [0032] FIG. 4 illustrates a perspective view of one embodiment of a register boot with flanges of the present invention. [0033] FIG. 5 illustrates a perspective view of one embodiment of a flexible coupler of the present invention. [0034] FIG. 6 illustrates a perspective view of one embodiment of a 90-degree takeoff of the present invention. [0035] FIG. 7 illustrates a perspective view of one embodiment of a straight takeoff of the present invention. [0036] FIG. 8 illustrates a perspective view of one embodiment of a rigid pipe of the present invention. [0037] FIG. 9 illustrates a perspective view of one embodiment of a straight boot of the present invention. [0038] FIG. 10 illustrates a perspective view of one embodiment of a rigid coupler of the present invention. [0039] FIG. 11A illustrates a front view of one embodiment of a duct runner of the present invention prior to assembly. [0040] FIG. 11B illustrates a front view of one embodiment of a duct runner of the present invention after assembly and forming a rectangular duct. [0041] FIG. 11C illustrates a perspective view of one embodiment of a duct runner of the present invention after assembly and forming a duct. [0042] FIG. 11D illustrates a front view of the scoring of one embodiment of the duct runner in FIG. 11A taken along line 11 D of the present invention. [0043] FIG. 12 illustrates a perspective view of one embodiment of a duct runner end cap of the present invention. [0044] FIGS. 13A-13C illustrate another embodiment of a rigid pipe. [0045] FIGS. 14A-14C illustrate another embodiment of a register duct. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0046] The present invention provides a complete plastic HVAC component system for distributing air and method for installing the same. FIG. 1 illustrates one embodiment of a heating and cooling system that uses various embodiments of the present invention. In FIG. 1 a furnace 1 is shown. The furnace 1 has a plenum 2 with duct 3 extending outwardly from the plenum 2 . The duct 3 is capped using an end cap 4 . Duct openings 50 are created on the duct wall 51 . The first opening 23 of the 90-degree takeoff 6 and straight takeoff 5 are lined up flush with the duct opening 50 . The flange 27 extending perpendicularly and outwardly from the first opening 23 of the takeoffs 5 , 6 is used to secure the takeoffs to the duct wall 51 . The tight connection between the flange 27 and the duct wall 51 prevents air from passing between the flange 27 and the duct wall 51 . A 6-inch diameter pipe, whether flexible 10 or rigid 7 , is connected to the 6-inch integrated collar 16 . A rib 22 along the collar 16 retentively engages the pipes 7 , 10 and secures the pipes against air leakage and falling off. If 7-inch diameter pipes 7 , 10 are used, the 6-inch integrated collar 16 is removed and the pipe is connected to the 7-inch integrated collar 17 having a rib 21 for retentively engaging the pipe. A coupler, whether rigid 9 or flexible 8 , can be used to secure pipes 7 , 10 to each other. The couplers 8 , 9 have integrated collars 16 , 17 for securing to both 6 or 7-inch pipes 7 , 10 . Additionally, ribs 21 and 22 secure the connection between the pipes 7 , 10 and the collars 16 , 17 from coming apart and prevent air from leaking from the connection. Torpedo 11 , register 13 and straight 14 boots have integrated collars 16 , 17 for connecting to both 6 and 7-inch pipes, whether flexible 10 or rigid 7 type of pipe. Both integrated collars 16 , 17 have ribs 21 , 22 for retentively engaging the pipe and sealing against air leakage from the first opening 23 . The torpedo 11 , register 13 and straight 14 boots each have a rectangular opening 25 and provide a means for attaching the boots to a register 52 . Thus, air is efficiently delivered from the furnace 1 to each register 52 by traveling through the duct 3 , duct opening 50 , straight 5 or 90-degree 6 takeoffs, flexible 10 or rigid 7 pipes and into a torpedo 11 , register 13 or straight 14 boot attached to the register 52 . [0047] FIG. 2 illustrates the 90 degree regular plastic register boot 13 in greater detail. The regular plastic register boot 13 includes a unitary body 15 of plastic. The plastic is preferably an injection molded thermoplastic. The unitary body 15 has a substantially circular first opening 23 for connecting to a flexible 10 or rigid 7 pipe. The unitary body 15 also has a substantially rectangular second opening 20 for connection to a register 52 . Thus air travels from the flexible 10 or rigid 7 pipe and through the first opening 23 , the unitary body 15 , the second opening 20 and to the register 52 . Due to the unitary plastic construction, the register boot is seamless thereby preventing loss of air within the register boot itself. Thus, the unitary plastic is generally advantageous over a multi-piece construction. A multi-piece construction would also tend to increase the labor required in installing the register boot. [0048] The unitary body 15 has integrated collars 16 and 17 for fitting the plastic register boot 13 to different sizes of diameter flexible 10 and rigid 7 pipe. For example, the collar 16 is preferably adapted to fit 6-inch diameter flexible 10 or rigid 7 pipe while the collar 17 is preferably adapted to fit 7-inch diameter flexible 10 or rigid 7 pipe. Because the unitary body is of a plastic material, the second collar 16 can be cut away from the first collar 17 as needed. This is advantageous because only one plastic register boot needs to be stocked as opposed to two plastic register boots. This same type of connection can also be used in other types of fittings as well. The first collar 16 has a first rib 22 and the second collar 17 has a second rib 21 . The ribs 22 , 21 , assist in holding ductwork, preferably flexible 10 and rigid 7 pipe, in place. [0049] The unitary body 15 includes a central member 18 with a rectangular mouth 19 for connection to the register 52 . The central member 18 shown provides a 90 degree angle between the register 52 and the pipe 7 , 10 . The present invention, however, contemplates that the central member 18 can be configured differently for other angles. [0050] FIG. 3 illustrate a torpedo boot embodiment of the present invention. In FIG. 3 , the torpedo boot plastic register boot 11 is shown. Note that the torpedo boot is similar to the regular plastic register boot shown in FIG. 2 , however, the torpedo register boot has a torpedo boot central member 24 of a different configuration. The torpedo boot 11 has a substantially rectangular opening 25 in a rectangular mouth 26 for connection to a register 52 . Note that the torpedo register boot 11 is configured for a different type of connection than the register boot shown in FIG. 2 as the rectangular opening 25 is oriented differently with respect to the pipe. Also, the torpedo boot plastic register boot has a first rib 22 and a second rib 21 for assisting in the connection of pipe, preferably flexible 10 or rigid 7 pipe. [0051] FIG. 4 illustrates another embodiment of a plastic register boot with a flange or lip. The plastic register boot 12 has a flange or lip 27 with a first end 28 and a second end 30 extending outwardly from the central member 33 of the plastic register boot 12 . One advantage of the flange 27 is that in floor applications the flange can be used to support the plastic register boot 12 in place during the installation process. This configuration is advantageous as it allows a single person to install the plastic register boot as opposed to requiring one person to hold the register boot in place from above with a second person working from below. Thus the flange or lip 27 provides a significant savings in the labor cost associated with installation. The flange 27 also has a plurality of tabs ( 29 , 31 and 32 ) to assist in holding the plastic register boot in place, particularly during the installation process. Each of the tabs ( 29 , 31 and 32 ) extend outwardly from the flange 27 . [0052] FIG. 5 illustrates a flexible coupler of the present invention. As shown in FIG. 5 , the flexible coupler 8 includes a first opening 23 and a second opening 20 on opposite ends of the flexible coupler 8 . As the flexible coupler 8 is flexible, the flexible coupler 8 can be configured and bent at different angles to replace numerous types of angled joints associated with sheet metal ductwork pipes. The flexible coupler 8 is made of a plastic material and is adapted for fitting either different sizes of flexible 10 or rigid 7 pipe. Because the integral collars 16 and 17 are of different diameters, the flexible coupler can fit flexible 10 pipe and rigid 7 pipe of different diameters. For example, flexible pipe can fit a 6-inch diameter flexible 10 or rigid 7 pipe when the first collar 16 is in place. The first collar 16 can be cut away from the second collar 17 which can fit a 7-inch diameter flexible 10 or rigid 7 pipe. Due to the use of plastic material, the flexible coupler can be easily cut. [0053] It should also be apparent that the flexible coupler 11 can fit one size of flexible 10 or rigid 7 pipe on one hand and a different size of flexible 10 or rigid 7 pipe on the other end. Thus, a single flexible coupler 11 replaces numerous types of connectors used with sheet metal. The flexible coupler 11 includes a first rib 22 and a second rib 21 to assist in connection to ductwork, especially flexible 10 or rigid 7 pipe. When connecting to flexible 10 or rigid 7 pipe, the first rib 22 or second rib 21 helps maintain a secure connection. [0054] FIG. 6 illustrates the 90-degree takeoff 6 in greater detail. The 90-degree takeoff 6 includes a unitary body 15 of plastic. The plastic is preferably an injection molded thermoplastic. The unitary body 15 has a substantially circular first opening 23 with a flange 27 extending perpendicularly and outwardly therefrom for securing the first opening 23 over top of the duct opening 50 in the duct wall 51 of the duct 3 . The unitary body 15 also has a substantially circular second opening 20 for connection to a flexible 10 or rigid 7 pipe. Thus air travels from the duct 3 and through the duct opening 50 and the first opening 23 , the unitary body 15 , the second opening 20 and to the flexible 10 or rigid 7 pipe. Due to the unitary plastic construction, the 90-degree takeoff is seamless thereby preventing loss of air within the takeoff itself. Thus, the unitary plastic is generally advantageous over a multi-piece construction. A multi-piece construction would also tend to increase the labor required in installing the 90-degree takeoff. [0055] On the side of the second opening 20 , the unitary body 15 has integrated collars 16 and 17 for fitting the 90-degree takeoff 6 to different sizes of diameter flexible 10 and rigid 7 pipe. Note that the integrated collars are identical in feature, function and dimensions as the integrated collars used on the individual register boots in FIGS. 2-4 . [0056] The 90-degree takeoff 6 insures seamless distribution of air from within a duct to the connecting pipe, whether flexible 10 and rigid 7 pipe. Because the plastic duct 3 is easily cut and does not present a sharp edge after cutting, duct openings 50 are safe to work in and around with one's bare hands. With sheet metal, duct openings create potential work hazard spots. However, the plastic duct wall 51 allows seamless implementation of takeoffs. Additionally, flange 27 insures that the first opening 23 lies flush and securely fastened to the duct wall 51 without risking injury or loss of air between the two surfaces. The 90-degree takeoff 6 a unitary body 15 includes a central member 18 . The central member 18 shown provides a 90 degree angle between the duct wall 51 and the pipe 7 , 10 . The present invention, however, contemplates that the central member 18 can be configured differently for other angles. [0057] FIG. 7 illustrates the straight takeoff 5 in greater detail. The straight takeoff 5 incorporates the identical features, functions, advantages and dimensions as the 90-degree takeoff except that the unitary body 15 is straight thereby providing a straight connection between the duct wall 51 and the pipe 7 , 10 . [0058] FIG. 8 illustrates a rigid pipe of the present invention. As shown in FIG. 8 , the rigid pipe 7 includes a first opening 35 and a second opening 36 on opposite ends of the pipe 7 . Attached to the first 35 and second 36 opening is a coupling collar 34 for connecting to a boot, takeoff, coupler or pipe. It is preferred that the rigid pipe 7 have a 6 or 7-inch diameter. The rigid pipe 7 can be connected to another section of rigid pipe 7 having the same diameter by cutting away the coupling collar 34 on the one end of a pipe and inserting into the coupling collar 34 of another section of pipe. The rigid pipe 7 having a 6-inch diameter can be connected to the integrated collar 16 of the boot, takeoff or coupler having a similar 6-inch diameter. Additionally, the rigid pipe 7 having a 7-inch diameter can be connected to the integrated collar 17 of the boot, takeoff or coupler having a similar 7-inch diameter. The rib 22 on the integrated collar 16 and the rib 21 on the integrated collar 17 help to secure the boot, takeoff or coupler to the pipe and create a seal against air leakage. [0059] FIG. 9 illustrates the straight plastic register boot 14 in greater detail. The straight plastic register boot 14 includes a unitary body 15 of plastic. The plastic is preferably an injection molded thermoplastic. The unitary body 15 has a substantially circular first opening 23 for connecting to a flexible 10 or rigid 7 pipe. The unitary body 15 also has a substantially rectangular second opening 20 for connection to a register 52 . Thus air travels from the flexible 10 or rigid 7 pipe and through the first opening 23 , the unitary body 15 , the second opening 20 and to the register 52 . Due to the unitary plastic construction, the register boot is seamless thereby preventing loss of air within the register boot itself. Thus, the unitary plastic is generally advantageous over a multi-piece construction. A multi-piece construction would also tend to increase the labor required in installing the register boot. [0060] The unitary body 15 has integrated collars 16 and 17 for fitting the straight boot 14 to different sizes of diameter flexible 10 and rigid 7 pipe. For example, the collar 16 is preferably adapted to fit 6-inch diameter flexible 10 or rigid 7 pipe while the collar 17 is preferably adapted to fit 7-inch diameter flexible 10 or rigid 7 pipe. Because the unitary body is of a plastic material, the second collar 16 can be cut away from the first collar 17 as needed. This is advantageous because only one plastic register boot needs to be stocked as opposed to two plastic register boots. This same type of connection can also be used in other types of fittings as well. The first collar 16 has a first rib 22 and the second collar 17 has a second rib 21 . The ribs 22 , 21 , assist in holding ductwork, preferably flexible 10 and rigid 7 pipe, in place. [0061] The unitary body 15 includes a central member 18 with a rectangular mouth 26 for connection to the register 52 . The central member 18 provides a straight connection between the register 52 and the pipe 7 , 10 . [0062] FIG. 10 illustrates a rigid coupler of the present invention. The rigid coupler 9 is similar to the flexible coupler 8 shown in FIG. 5 . Note that the difference between the flexible coupler 8 and the rigid coupler 9 is a unitary body 15 that is flexible. Particularly, the rigid coupler 9 has a rigid unitary body, whereas the flexible coupler 8 has a flexible unitary body. The rigid coupler 9 offers the benefits of rigid member. The rigid coupler 9 can also be used in situations where it supports the weight of the pipes connected thereto. [0063] FIGS. 11A-D illustrates a duct of the present invention. The duct 3 is assembled from a sheet of plastic having sufficient wall thickness to support its own weight after assembled and resist damage during storing, assembly and installation. Particularly, FIG. 11A shows the plastic sheet 38 having a first 44 and second 43 connecting edge. The first connecting edge 44 has a raised flange 40 connected thereto. The plastic sheet 38 has scorings 39 running parallel and the length of the sheet 38 . The scorings 39 have a separation distance such that a rectangular duct shown in FIG. 11B is formed when folded along the scorings 39 . The rectangular shape of the duct 3 is retained by overlapping and connecting the raised flange 37 to the second connecting edge 43 . FIG. 11C illustrates the duct 3 after being constructed. The duct 3 has a rectangular body 41 connecting the first opening 35 and second opening 36 . FIG. 11D illustrates the scoring 39 in the plastic sheet 38 along lines 11 D as shown in FIG. 11A . The duct 3 is easy to cut to a desired length and being plastic, is also easily cut to create openings within the duct wall 51 for securing a takeoff 5 , 6 thereto. [0064] FIG. 12 illustrates an end cap of the present invention. The end cap is constructed of a rectangular surface 47 having an edge 48 and a wall 46 . The wall 46 is connected to the edge 48 of the rectangular surface 47 . The wall 46 extends perpendicularly and outwardly from the rectangular surface 47 forming a cap for closing off the end of a duct. [0065] FIGS. 13A-13C illustrates another embodiment of a duct of the present invention. The duct 60 has a first open end 62 and a second opposite open end 64 . The first open end 64 is configured for coupling to another tube or duct. As shown in FIG. 13B , an outer portion 66 is shown which slightly angles inwardly such as at a 20 degree angle. The prior art invention contemplates that the angle may vary, such as in a preferred range of 10 degrees to 30 degrees. [0066] An annular lip 68 is provided to assist in securing the connection of the duct 60 to another item or duct work. The annular lip 68 protrudes outwardly from the outer most portion 66 . After the annular lip 68 , a portion 70 , the outermost portion 66 continues to be angled slightly inwardly. The portion 70 is operatively connected to a transition portion 72 which gradually transitions to the inner portion 74 . In operation, the end 64 assists in providing a secure attachment. [0067] The duct 60 may be sized for standard sizes of duct work such as 6 inch or 7 inch. For example, the diameter of the second end may be approximately 7 inches with the diameter of the first end being slightly greater. Similarly, the diameter of the second end may be approximately 6 inches with the diameter of the first end being slightly greater. The substantially cylindrical body of the duct may have an average wall thickness of about 0.08 inches. [0068] FIGS. 14A-14D illustrates another embodiment of a plastic register boot. The plastic register boot 80 is formed of a heat resistant plastic. There is a first opening 82 which is substantially circular and a second opening 84 which is substantially rectangular. A first collar 86 and a second collar 88 are shown. A first rib 90 is shown, a second rib 92 , and a third rib 94 are shown. Each of the ribs 90 , 92 , 94 are annular ribs protruding outwardly. A transition portion 96 is also shown. The transition portion 96 has a circular cross section which expands into a rectangular cross section. [0069] One skilled in the art having the benefit of this disclosure will appreciate that the present invention extends beyond the specific embodiments shown in. The present invention contemplates numerous variations in the particular type of plastic used, the manner in which the plastic if formed, the shape or configuration of the register boots, joints, or other fittings, the type of flex pipe or diameter of flex pipe that can be used, and other variations. These and other variations of the present invention are well within the spirit and scope of the invention. The present invention is not to be limited to the specific embodiments shown herein.	A complete plastic HVAC system assembled using individual plastic components for ensuring the efficient and quiet distribution of air from a central air unit to multiple distribution points and preventing heating and cooling losses, the need for installers to stock multiple sized and shaped components, the accumulation of dust, dirt and pollens during storing, installing and use on the surfaces of the individual components. The fittings have a collar sizable to fit both 6 and 7-inch pipe, whether flexible or rigid. The use of plastic fittings, duct and pipe removes the potential of injury commonly associated with conventional metal ductwork, while providing seamless components that can be configured for any type of installation and insure an air tight connection between adjoining surfaces. The individual fittings include a register boot, torpedo boot, straight boot, rigid and flexible pipe and couplers, straight and 90-degree takeoffs, a plastic duct and duct end cap.	5
[0001] Priority is claimed to provisional application Ser. No. 60/860,570, filed Nov. 21, 2006, entitled: A Two-Wheeled Human-Powered Vehicle Propelled by an Elliptical Drive Train, which is referred to and incorporated herein in its entirety by this reference. FIELD OF THE INVENTION [0002] The present invention generally relates to bicycles. More particularly, the invention concerns a bicycle having an elliptical drive train. BACKGROUND OF THE INVENTION [0003] The most common human-powered vehicle is the bicycle. Use of the bicycle for exercise, recreation, and transportation is well-known. Operators of conventional bicycles are in a seated position and pedal in an essentially circular motion to perform the mechanical work necessary to propel the vehicle. During operation, the operator's upper body is typically bent forward at the waist and held in place by the muscles of the arms, shoulders, abdomen, and lower back. This most common riding position is relatively stressful. Bicycle riders often experience pain, discomfort, and/or numbness in the pelvic region from sitting on the bicycle seat or “saddle”, and discomfort in the lower back, arms, and shoulders from the bent-over riding position. [0004] To alleviate the discomfort associated with prolonged use of conventional bicycles, recumbent bicycles in which the operator propels the bicycle from a reclined position are known. Although recumbent bicycles alleviate much of the discomfort associated with conventional bicycles, the reclined riding position makes these vehicles less stable and more difficult to ride. The recumbent bicycle is also limited as a commuter vehicle because the low-to-the-ground configuration allows obstacles to easily obstruct the operator's line of sight and makes him or her less visible to other vehicles, cyclists, and pedestrians. In addition, because operators of conventional and recumbent bicycles are seated, they do not receive the musculoskeletal benefits of weight-bearing exercise when operating these vehicles. [0005] Therefore, there remains a need to overcome one or more of the limitations in the above-described, existing art. BRIEF DESCRIPTION OF THE DRAWINGS [0006] FIG. 1 shows a perspective view of one embodiment of the bicycle; [0007] FIG. 2 shows a side elevation view of the bicycle of FIG. 1 , depicting schematically the elliptical pedaling profile; [0008] FIG. 3 shows a side elevation view of the bicycle of FIG. 1 , depicting schematically an operator's zone; [0009] FIG. 4 shows a perspective view of another embodiment of the bicycle; [0010] FIG. 5 shows a perspective view of yet another embodiment of the bicycle; [0011] FIG. 6 shows a perspective view of yet another embodiment of the bicycle; [0012] FIG. 7 shows a perspective view of yet another embodiment of the bicycle that includes an adjustable guide track; [0013] FIG. 8 shows a close-up perspective view of adjustable crank arms that may be coupled to the bicycle; [0014] FIG. 9A shows a perspective view of one embodiment of an adjustable foot platform that may be coupled to the bicycle; [0015] FIG. 9B shows a perspective view of another embodiment of an adjustable foot platform that may be coupled to the bicycle; [0016] FIGS. 10A-L show side elevation views of different embodiments of load wheel retention devices that may be coupled to the bicycle; [0017] FIG. 11 shows a perspective view of one embodiment of an adjustable steering tube that may be coupled to the bicycle; [0018] FIG. 12 shows a perspective view of one embodiment of a direct drive system that may be coupled to the bicycle; [0019] FIG. 13A shows a perspective view of another embodiment of the bicycle that includes a foldable frame; [0020] FIG. 13B shows a perspective view of the bicycle depicted in FIG. 13A after it has been folded; and [0021] FIG. 14 shows a perspective view of yet another embodiment of the bicycle. [0022] It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. The Figures are provided for the purpose of illustrating one or more embodiments of the bicycle with the explicit understanding that they will not be used to limit the scope or the meaning of the claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the bicycle of the present invention. It will be apparent, however, to one skilled in the art that the bicycle may be practiced without some of these specific details. For example, a variety of load wheel retention devices may be employed. Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than as limitations on the bicycle. That is, the following description provides examples, and the accompanying drawings show various examples for the purposes of illustration. However, these examples should not be construed in a limiting sense as they are merely intended to provide examples of the bicycle rather than to provide an exhaustive list of all possible implementations of the bicycle. [0024] The present disclosure relates generally to human-powered transportation, and more specifically to transport, exercise, and recreational vehicles powered by an elliptical pedaling motion that generally mimics the kinematics of walking or running. The apparatus, of which one embodiment is a bicycle, described herein provides an improved means of human-powered transportation that has advantages over conventional bicycles, scooters, upright step-cycles, and other human-powered vehicles. [0025] As defined herein, a “bicycle” is every vehicle propelled, at least in part, by human power in the form of feet, or hands, acting upon pedals, having at least two wheels, except scooters and similar devices (which are defined as vehicles operated by a foot contacting the ground). The term “bicycle” also includes three and four-wheeled human-powered vehicles. [0026] More specifically, disclosed herein is a low cross-over height bicycle powered by an elliptical pedaling motion that generally mimics the kinematics of running or walking and provides a means of human-powered transportation that has advantages over conventional upright step-cycles, bicycles, and scooters. Also disclosed herein are methods for enabling the operator to adjust the pedaling profile of such a vehicle. [0027] An upright step-cycle is known in the art, but has several drawbacks. For example, the length of the wheelbase of several upright step-cycles described limits the means by which they can be transported in another vehicle, such as a passenger car, and prevents them from being turned around on narrow bike paths or streets without the operator dismounting the vehicles. Conventional upright step-cycles also have sprockets and a chain positioned near the operator. If contacted, these moving parts can damage the operator's clothing and/or injure the operator. Furthermore, conventional upright step-cycles have frames that position support structures in the operator's zone, discussed in detail below. Frame members located in the operator's zone are likely to injure the operator if he or she contacts them while riding or during a fall. Frame members located in the operator's zone also make mounting and dismounting the vehicle more difficult. [0028] In addition, conventional upright step-cycles lack several features that could enable the operator to easily modify the vehicle's pedaling profile and thereby allow a single vehicle to be adjusted to accommodate a wide range of different sized riders. As discussed above, the path of motion through which the operator's foot travels while pedaling these vehicles is generally elliptical. Some people prefer this generally elliptical motion to the generally circular motion used to propel a conventional or recumbent bicycle because the generally elliptical motion more closely mimics walking, running, or climbing and has been shown to be a more effective means for strengthening the leg muscles than cycling while avoiding much of the stress and impact generated by running. However, because the pedaling motion mimics human movement, operators with different anatomical dimensions will generally require different pedaling profiles. Specifically, a taller operator would likely require a pedaling profile with a longer stride length than a shorter operator would. In addition, a more aggressive operator might prefer a steeper foot platform take-off angle so that he or she could generate more low-end torque, while a less aggressive rider might prefer a flatter pedaling profile to reduce foot and knee flexion during the pedal stroke. [0029] As discussed below, the shape of the pedal stroke is generally determined by the length of the crank arms, the length of the foot links, the location of the foot platforms on the foot links, and the angle of the foot link guide tracks. Conventional upright step-cycles lack easy methods for adjusting the length of the crank arms and the location of the foot platforms. Enabling operators to easily optimize the pedaling profile by adjusting these aspects of the propulsion system would enhance the functionality of an upright step-cycle. [0030] Another form of human-powered transportation is the scooter. Conventional scooters are operated in a standing position. The operator propels a scooter forward by pushing one leg against the ground in a rearward direction. Scooters have the advantage of being more comfortable to ride than conventional bicycles without many of the drawbacks of recumbent bicycles. Because the operator of a scooter rides in an upright position, he or she does not experience the numbness and pain caused by sitting on a seat or saddle. In addition, the operator is less susceptible to shoulder and lower back pain because he or she is not hunched over the handlebars. As compared to a recumbent bicycle, the operator's standing position reduces the likelihood that his or her line of sight will be obstructed and makes him or her more visible to other vehicles and pedestrians. A scooter is also more stable and easier to ride than a recumbent bicycle, thereby reducing the frequency of falling for unskilled operators. Moreover, riding a scooter is a weight-bearing exercise that provides the operator with a means of strengthening the leg muscles and bones that is not available to operators of conventional and recumbent bicycles. [0031] However, the scooter does have disadvantages. Although an operator can travel longer distances at higher speeds on a scooter than he or she generally could by walking or running, a scooter's propulsion mechanism is not very efficient, especially when compared to that of a conventional bicycle. As a result, scooters are generally not used for business commuting, sustained exercise, or for other applications that require long-distance or high-speed travel. [0032] Mechanical devices that improve the efficiency of conventional scooters are known. A typical pedal-driven scooter is propelled forward by the operator pumping one or two platforms up and down. Although this mechanism can be a more efficient means of propulsion than pushing backwards against the ground, it is not ideal because it must be translated into rotational motion to propel the vehicle forward. These mechanisms can also cause knee injuries because of the operator's need to reverse his or her leg's direction of motion at the top and bottom of each pedal stroke. Therefore, the introduction of a more efficient and lower impact scooter propulsion system would enhance the utility of pedal driven scooters. [0033] With reference now to the Figures, disclosed herein is an operator-propelled vehicle in which rotation of left and right crank arms causes the respective left and right foot platforms to move along an elliptical path. The term “elliptical” with regard to “elliptical pedaling motion” or “elliptical pedaling profile” or “elliptical path” or “elliptical motion” is intended in a broad sense to describe a closed path of motion having a relatively longer first axis and a relatively shorter second axis (which extends perpendicular to the first axis as in an ellipse). [0034] The embodiments shown and described herein are generally symmetrical about a vertical plane extending lengthwise. Reference numerals are generally used to designate both the “right-hand” and “left-hand” parts, and when reference is made to one or more parts on only one side of the apparatus, it is to be understood that corresponding part(s) may be disposed on the opposite side of the apparatus. The portions of the frame that are intersected by the plane of symmetry exist individually and thus, may not have any “opposite side” counterparts. Also, to the extent that reference is made to forward or rearward portions of the apparatus, it is to be understood that the drive arm assembly is movable in either of two opposite directions. [0035] FIG. 1 shows a general embodiment of the apparatus, or bicycle 100 . The apparatus 100 generally includes a foot link assembly 105 movably mounted on a frame, or frame structure 110 , on which a pair of wheels (front wheel 115 , rear wheel 117 ) are mounted. Generally, each foot link assembly 105 is moveably mounted to the frame 110 at its forward end where it is slideably coupled to a foot link guide track 255 and at its rearward end where it is rotatably coupled to the crank assembly 215 . [0036] Generally, each foot link assembly 105 includes a foot link 205 , each with a foot platform 210 , and a load wheel 250 . The foot platforms 210 on which the operator stands are mounted on an upper surface of each foot link 205 near a forward end of each foot link 205 . Below each foot platform 210 near the frontal section of each foot link is a load wheel 250 that contacts a sloping foot link guide track 255 . In the embodiment depicted in FIG. 1 , two foot link guide tracks 255 run parallel to each other on either side of the longitudinal axis of the apparatus 100 and are integral with the frame 110 . The load wheel 250 and bearings are mounted to a fixed axle to allow nearly frictionless linear motion of the foot links 205 along the foot link guide tracks 255 and provide rotational freedom of the foot links 205 with respect to the foot link guide tracks 255 . [0037] As shown in FIG. 2 , during pedaling, the operator (not shown) uses his mass in a generally downward and rearward motion as in walking or jogging to exert a force on the foot platforms 210 and thereby, the foot links 205 . This force causes the load wheel to roll down the slope of the foot link guide track 255 towards the rear of the apparatus 100 and rotate the crank arms 235 about the crank arm bearing 245 , turning the drive sprocket 240 . As with conventional bicycles, rotating the drive sprocket 240 causes the rear wheel sprocket 135 to rotate because they are linked by a chain or belt 130 . It will be appreciated that the chain or belt 130 may also comprise a rotating shaft or other drive means. Rotating the rear wheel sprocket 135 causes the rear wheel 117 to rotate because the rear wheel sprocket is attached to the rear wheel hub 145 . Rotating the rear wheel 117 provides motive force that enables the apparatus 100 to move along a surface. The apparatus 100 can employ a “fixed” or “free” rear wheel, as is known in the art. The apparatus 100 can also employ a planetary gear hub having different gear ratios, as manufactured by Shimano, Sturmey-Archer and others. [0038] One feature of the apparatus, or bicycle 100 is that the pedaling motion described above results in the operator's foot traveling in a shape that can be described as generally elliptical. Propulsion using an elliptical pedaling motion, as opposed to an up and down pedaling motion or a circular pedaling motion, has the advantage of substantially emulating a natural human running or walking motion. Further, an elliptical pedaling motion is a simpler and more efficient means to rotate the rear wheel 117 than is, for example, a vertical pumping motion. Moreover, the major axis of the ellipse in an elliptical pedaling motion can be much longer than the stroke length of a circular or vertical pumping pedaling motion, allowing the operator to employ a larger number of muscle groups over a longer range of motion during the pedal stroke than he or she could employ in a circular or up and down pedaling motion. [0039] As shown in FIG. 2 , dashed line E depicts the generally elliptical path that the ball of the operator's foot would take throughout the pedaling motion. The region where the ball of the operator's foot contacts the foot platform 210 is labeled as item F. The power stroke during forward motion is from front-to-back and follows the lower half of the elliptical path E. As the operator's foot moves rearward through the power stroke of the described elliptical pedaling motion, the heel portion falls more quickly than does the toe portion. The return stroke during forward motion is from back-to-front and follows the upper half of the elliptical path E. As the operator's foot moves forward through the return stroke of the described elliptical pedaling motion, the heel portion of the foot rises more quickly than does the toe portion. [0040] As illustrated in FIG. 2 , the shape of the elliptical path E is generally defined by the following parameters: (1) the length of the major axis A; (2) the length of the minor axis B; and (3) the major axis angle γ. The length of the major axis A is generally equal to the stride length of the pedaling motion. The length of the minor axis B relative to the length of major axis A generally determines the vertical lift of the operator's foot and angular foot plantar-flexion throughout the pedaling motion. Decreasing the ratio of A to B increases the vertical lift of the operator's foot and increases the angular foot plantar-flexion. Conversely, increasing the ratio of A to B reduces the vertical lift of the operator's foot and decreases the angular foot plantar-flexion. As the ratio of A to B approaches infinity, the elliptical path E collapses into a straight line of length A and eliminates the vertical lift altogether. [0041] The major axis angle γ of the ellipse reflects the incline angle of the pedaling motion. A major axis angle γ of zero degrees emulates natural walking or running motion on flat ground. Increasing the major axis angle γ emulates natural walking or running motion on an incline. Foot link guide track angle θ is the angle of the foot link guide track 255 from horizontal and is generally parallel with the major axis angle γ. [0042] The three parameters that govern the shape of the generally elliptical pedaling path E (major axis A, minor axis B, and major axis angle γ, discussed above) are generally a function of the following frame and drive mechanism dimensions: crank arm length C, foot link length D, crank pivot offset P, operator foot offset J, and foot link guide track angle θ. Crank arm length C is the distance between the center of the crank arm bearing 245 to the foot link bearing 220 . Foot link length D is the distance between the center of the load wheel 250 and the foot link bearing 220 . Operator foot offset J is the distance from the center of the load wheel 250 to the region where the ball of the operator's foot contacts the foot platform, point F. Foot link guide track angle θ is the angle of the foot link guide track 255 from horizontal and is generally parallel with the major axis angle γ. As discussed below, modifying these parameters will change the elliptical pedaling profile experienced by the operator. [0043] As illustrated in FIGS. 1-7 , the frame, or frame structure 110 of the apparatus 100 can be comprised of a variety of materials. FIG. 1 depicts one embodiment of the apparatus 100 in which the frame 110 is comprised of a rigid tubular metal, such as aluminum, steel, or titanium. As illustrated in FIG. 1 , the frame structure 110 includes a lower frame member and two foot link guide tracks 255 that, in this embodiment, also act as structural frame members. FIG. 5 depicts an embodiment of the apparatus 100 in which the frame 110 is comprised of sheet metal, and in this embodiment, one frame member may be the lower portion of the frame 110 (nearest the ground) and a second frame member may be the foot link guide track 255 that comprises an upper portion of the frame 110 . FIG. 6 depicts an embodiment of the apparatus 100 in which the frame 110 is comprised of a graphite composite, and in this embodiment, similar to the embodiment illustrated in FIG. 5 , one frame member may be the lower portion of the frame 110 (nearest the ground) and a second frame member may be the foot link guide track 255 that comprises an upper portion of the frame 110 , even though the two frame members may be formed together. [0044] Other materials may also be used to construct the frame for the apparatus, such as plastics, alloys, other metals, etc. The frame 110 provides the structural rigidity necessary to support the rider while he or she is operating the apparatus 100 . The frame 110 also connects the movable portions of the apparatus 100 together into a complete system. [0045] One of the features common to all of the proposed embodiments of apparatus 100 is a low cross-over height frame. As defined herein, a frame has a low cross-over height if there are no structural frame members positioned in the operator's zone. Generally, the operator's zone is the area of space occupied by the operator when riding the apparatus. For example, one embodiment of the operator's zone is illustrated in FIG. 3 , and comprises an area defined by points K and L, and line N. Point K is the aft-most position of the load wheel 250 , point L is the mid-point of travel of the load wheel 250 , and line N is formed by a line that extends between the tops of the front wheel 115 and rear wheel 117 . During operation, the load wheel 250 travels from a forward-most position 103 to a rear-most, or aft-most position K. As shown in FIG. 3 , the mid-point of travel for the load wheel 250 is point L, which is half the distance of the load wheel total distance of travel 107 . Put differently, the load wheel total distance of travel 107 is the maximum stride length that an operator would be able to achieve, and may range from about 14 inches to about 26 inches. As shown in FIG. 3 , the operator's zone extends from line N upwards, and is bounded by two substantially vertical lines that extend from points K and L. [0046] It will be appreciated that the operator's zone may extend further forward or backward depending on the amount of forward and rearward movement the operator must undertake when operating a specific embodiment of the apparatus. For example, for some embodiments, point L may be defined as the location of the ball of the operator's foot when it is located at the forward extreme of the pedal stroke (point 103 ) on the foot platform 210 , and point K may be defined as the heel of the operator's foot when it is on the foot platform 210 and the load wheel 250 is at its aft-most position. Similarly, it may be appreciated that for embodiments where the front wheel 115 and the rear wheel 117 are small (have diameters less than 20 inches), line N may be set at a given distance off of the ground (approximately 26 inches) rather than formed by a line that extends between the tops of the front wheel 115 and rear wheel 117 . [0047] FIGS. 1 , 4 , 5 , 6 , 7 , 12 , 13 , and 14 depict several different proposed embodiments, all of which have low cross-over height frames 110 . As shown in FIG. 3 , generally, the frame 110 includes truss members 112 and two foot link guide tracks 255 . However, some frame 110 embodiments, like those shown in FIGS. 5 and 6 , do not include truss members 112 . Moreover, the foot link guide tracks 255 may be an integral component of the frame, as shown, for example, in FIGS. 4-6 . The individual guide tracks may also be integrated together to form a single guide track, as depicted in FIG. 14 . [0048] Low cross-over height frames 110 are safer and more convenient to use than conventional upright step-cycle or bicycle frames. The low cross-over height design is safer because there are no support structures in the operator's zone that could cause injury during a fall or during riding. These frames are also more stable to ride because they have a lower center of gravity. The low cross-over height design also makes the apparatus 100 easier and safer to mount and dismount because there are no support structures in the operator's zone to step over or around when mounting or dismounting. In addition, the low cross-over height makes the apparatus 100 easier to maneuver in tight spaces because it enables the operator to easily step across the apparatus 100 , which facilitates moving the apparatus 100 into and out of storage areas, trains, buildings, and the like. [0049] One consideration when designing low crossover-height frames 110 is stiffness in bending. Unlike conventional frames, a low cross-over height frame 110 does not include a structural member above the plane of the top of the wheels to provide stiffness in bending. Because the frame 110 must support the dynamic weight of the operator during riding, stiffness in bending is important not only to prevent frame member failure, but also to improve pedaling efficiency and handling. [0050] The proposed embodiments have been designed to provide sufficient frame 110 stiffness in bending. For example, the frame 100 design in FIG. 4 has a stiffness of approximately 2500 lbf/in. When the embodiment depicted in FIG. 4 is subjected to a 200 pound load in the center of the foot link guide tracks 255 , the frame 110 will deflect no more than about 0.08 inches, thereby minimizing the negative effects of frame flexing discussed above. This improved stiffness in bending is achieved by several features contained in the low cross-over height frame 110 , including incorporation of the foot link guide tracks 255 into the frame 110 as frame members, and the use of truss members 112 to enhance stiffness. [0051] As shown in several of the Figures, embodiments of the apparatus 100 include a steering mechanism 120 that may comprise handlebars 119 , a steering wheel (not shown), or other steering means. The steering mechanism 120 can be mounted upon a fixed or adjustable steering extender 125 that extends upward from the frame 110 . The steering mechanism 120 can be telescopically adjustable, as well as adjustable forward and backward, and can incorporate a pivot to provide rotational adjustability. One feature is that an adjustable steering mechanism will permit easy and safe use by a variety of operators having different heights and arm dimensions. [0052] FIG. 11 depicts a detailed view of one embodiment of a telescoping steering mechanism. In this embodiment, the steering extender 125 is held by a steering extender sleeve 126 . The inside diameter of the steering extender sleeve 126 is larger than the outside diameter of both the front fork steer tube 127 and the steering extender 125 . In this embodiment, the front fork steer tube 127 has been inserted into the bottom of the steering extender sleeve 126 and is clamped to it by means of one or more fasteners 128 , such as a bolt and nut, pin, clip or other means. In addition, the steering extender 125 is inserted into the top of the steering extender sleeve 126 and is clamped to it by means of another fastener 128 . The height of the steering mechanism 120 can be adjusted by varying the position where the steering extender sleeve 126 clamps to the steering extender 125 . FIGS. 13A-B depict a steering tube assembly with both translational and rotational adjustability. [0053] As shown in FIGS. 1 , 4 , and 6 , embodiments of the apparatus 100 can also incorporate a rear wheel cover 190 . The purpose of the rear wheel cover 190 is to prevent the operator's legs, feet, clothing, and other objects from contacting the rear wheel 117 . The cover 190 can be made from metal, plastic, graphite composite, fiberglass, or other materials. It can be attached to the frame by bolts, welds, brazes, or other methods, or it can be an integrated part of the frame 110 as shown in FIG. 6 . To facilitate transporting and maneuvering the apparatus 100 while walking, a handle 191 can be attached to, or incorporated into, the rear wheel cover 190 , or a handle 191 can be attached to, or incorporated into, the frame 110 and protrude through an opening in the rear wheel cover 190 . [0054] FIG. 1 depicts a rear wheel cover 190 with a handle 191 . The handle 191 is integrated into the rear wheel cover 190 and the rear wheel cover 190 is bolted to the frame 110 . FIG. 4 depicts a rear wheel cover 190 without a handle that is bolted to the frame 110 . FIG. 6 depicts a rear wheel cover 190 without a handle that is integrated into a carbon fiber frame 110 . [0055] Referring now to FIGS. 10A-B , each foot link 205 can be laterally constrained onto its respective foot link guide track 255 in a variety of ways. FIGS. 10A and 10B , which is a sectional view about section M-M shown in FIG. 10A , and FIGS. 10C and 10F depict one method of laterally constraining the foot link 205 . In this method, the load wheel 250 has a V-groove 305 that mates to the counterpart geometry of a substantially diamond-shaped foot link guide track 255 . The top of the foot link guide track 255 fits into the center of the groove of the load wheel 305 , thereby laterally constraining the foot link 205 . [0056] FIGS. 10D , 10 i , 10 J, and 10 K depict a similar mechanism for laterally constraining a foot link 205 onto a round or tubular-shaped foot link guide track 255 . In these embodiments, the contact surface of the load wheel 250 has a concave shape that mates with the counterpart geometry of the round foot link guide track 255 . The top of the foot link guide track 255 aligns with the center of the load wheel 250 and the foot link 205 is laterally constrained onto the foot link guide track 255 by the interface of the concave load wheel 205 and the round tube comprising the foot link guide track 255 . [0057] FIG. 10E depicts another method of laterally constraining a foot link 205 onto a foot link guide track 255 . This embodiment uses a load wheel carrier 271 that is attached to each foot link 205 . In the depicted embodiment, the load wheel carrier 271 holds two load wheels 250 . The load wheels 250 are set into the load wheel carrier 271 at opposing angles. The interaction of each load wheel 250 with the foot link guide track 255 results in the lateral constraint of the attached foot link 205 . Although a diamond shaped foot link guide track 255 is depicted in FIG. 10E , this method could also be used with round, tubular, or similarly shaped foot link guide tracks 255 . [0058] The lateral constraining methods discussed above are intended to prevent the foot link assembly from laterally disengaging with, or “falling off” of, the foot link guide track 255 . The list is not intended to be exhaustive. Its purpose is only to illustrate a few of the many methods of restraining the foot links 205 in the lateral direction. [0059] In addition to lateral constraint, each foot link 205 may also be retained in the normal direction (i.e., a direction generally perpendicular to the foot link guide track 255 ). That is, each foot link 205 may be restrained from “jumping off” the foot link guide track 255 . The foot links 205 could be subject to disengaging in the normal direction whenever, for instance, the apparatus 100 travels over sharply undulating or rough terrain, or strikes an obstacle. The retention methods discussed below are intended to prevent the foot link assembly from disengaging with the foot link guide track 255 in the normal direction during operation of the apparatus 100 . The list is not intended to be exhaustive. Its purpose is only to illustrate a few of the many methods of restraining the foot links 205 in the normal direction. [0060] FIGS. 10A , 10 B, 10 C, 10 D, 10 E, 10 F, and 10 i depict a method of normal retention in which one or more retaining links 605 holds a retaining member 610 underneath a feature of the foot link guide track 255 , or the foot link guide track 255 itself. The interaction of the retaining member 610 with the foot link guide track 255 or a feature on the foot link guide track 255 prevents the load wheel 250 from disconnecting with the foot link guide track 255 . [0061] There are many ways to vary this method of retention, including changing the shape, size, number or other characteristic of the retaining links 605 , changing the shape, size, number, or other characteristic of the retaining member 610 , changing the shape, size, or number of foot link guide tracks 255 , or changing the shape, size, number, or other characteristics of features connected to the foot link guide track 255 or frame 110 . For example, FIGS. 10F and 10 i depict just two kinds of the many features that could be attached to the foot link guide tracks 255 to facilitate retention. FIG. 10F depicts an eave-like structure, and FIG. 10 i depicts a rail-like structure. A variety of other features could be employed for this purpose. Similarly, FIGS. 10A and 10D depict different shapes of the retaining member 610 . FIG. 10A shows a round member and FIG. 10D shows a cylindrical member. In fact, the retaining member 610 could be any manner of bar, pin, wheel, cable, or other mechanism that could serve to prevent the load wheel 250 from disengaging with the guide track 255 . [0062] Moreover, the retaining link 605 or links can be designed to either hold the retaining member 610 at a fixed distance from the load wheel, or to allow for adjustment of that distance. FIGS. 10C , 10 D and 10 E depict retaining links 605 that hold the retaining member 610 at a fixed distance. FIG. 10B depicts one embodiment of a retaining link 605 in which a preloaded spring mechanism 630 holds the retaining member 610 in contact with the guide track 255 throughout the pedal stroke. The preloaded force can be adjusted by rotating the set screws 615 and 620 . This same system could also be used to establish and then adjust a gap between the retaining member 610 and the guide track 255 , thereby preventing the retaining member from contacting the guide track 255 except when needed to prevent the load wheel from disengaging with the guide track 255 . Such a gap can be set by rotating the set screws 615 and 620 . The gap can then be adjusted over time in the same manner to compensate for wear of the load wheel 250 . Again, the depictions described herein are meant to be illustrative only, and the apparatus 100 may include any number of variations and embodiments relating to retention of the load wheel 250 to the foot link guide track 255 . [0063] FIGS. 10G , 10 H, 10 J and 10 K illustrate several embodiments of an axle bar retention system. In this system, a retention member is passed through the axle of the load wheel such that it protrudes from one or both ends of the axle. The load wheel is constrained in the normal direction by the interface of this retention member and a structure attached to the frame 110 . The retention member can be any manner of pin, bolt, bar, or the like. [0064] For example, as shown in FIGS. 10G and 10H , the axle retention member 1010 protrudes from both sides of the load wheel 250 . In FIG. 10G , each end of the axle retention member 1010 passes through a slot 285 formed in the foot link guide track 255 . The interaction between the axle retention member 1010 and the slot 285 prevents the foot link 205 from disengaging with the foot link guide track 255 in the normal direction. Similarly, in FIG. 10H , each end of the axle retention member 1010 is positioned below a ledge 280 included in the foot link guide track 255 . The interaction between the axle retention member 1010 and the ledge 280 prevents the foot link 205 from disengaging with the foot link guide track 255 in the normal direction. [0065] In FIGS. 10J and 10K , only one end of the axle retention member 1010 protrudes from the load wheel 250 . In FIG. 10J , the protruding end of the axle retention member 1010 has a hole drilled through it. The hole captures a securing member 287 that is connected to the foot link guide tracks 255 or another part of the frame 110 . The securing member 287 can be any manner of rod, cable, bar, or similar item. Similarly, in FIG. 10K , the axle retention member 1010 is slotted to capture a securing member 287 that is connected to the foot link guide tracks 255 or another part of the frame 110 . In both embodiments, the interaction between the retention member 1010 and the securing member 287 prevents the foot link 205 from disengaging with the foot link guide track 255 in the normal direction. [0066] FIG. 10L depicts an alternative embodiment that provides both lateral and normal constraint. In this embodiment, the load wheel 250 has been replaced by a linear bearing 1030 . The linear bearing 1030 is free to slide along the foot link guide track 255 , however the lower portion 1020 of the linear bearing 1030 captures the foot link guide track 255 , thereby preventing the foot link 205 from disengaging from the foot link guide track 255 in the lateral or normal direction. [0067] As discussed above, there are several ways to modify the elliptical pedaling profile of the apparatus 100 . One method is to change the location of the ball of the operator's foot (identified as location F in FIGS. 2 , and 9 A-B) with respect to the load wheel 250 or the first end of each foot link 205 . Referring now to FIGS. 9A-B , the first end of the foot link 205 is the end of the foot link 205 that is directly adjacent to the load wheel 250 , and the second end of the foot link 205 is the end of the foot link 205 that is directly adjacent to the foot link bearing 220 (shown in FIG. 1 ). Modifying the location of the operator's foot 121 relative to the load wheel 250 or the first end of the foot link 205 changes the operator foot offset (identified as distance J in FIGS. 2 and 9 A-B). To achieve a flatter and more eccentric pedaling profile, the operator can position his or her foot closer to the first end of each foot link 205 . Alternatively, by positioning his or her foot further away from the first end of the foot link 205 , the operator can create a more circular and less eccentric pedaling profile. Because the distance between the operator's foot 121 and the load wheel 250 or first end of each foot link 205 influences the pedaling profile, the repeatability of adjustments to this distance ensures that the operator can experience the desired pedaling profile. [0068] There are a variety of ways to enable the operator to repeatably modify the position of his or her foot relative to the first end of the foot link 205 . FIG. 9A depicts one method. In this embodiment, each foot platform designates a single position for an operator's foot 121 . The interface between each foot platform 210 and its respective foot link 205 is adjustable such that the foot platforms 210 can be attached onto the foot links 205 at different distances from the first ends of the foot links 205 . The attachment method in this embodiment is a pair of releasable clamps 905 that connect each foot platform 210 to its respective foot link 205 . This mechanism enables the operator to adjust each foot platform to achieve a repeatable placement of his or her foot relative to the first end of each foot link. In addition, each foot platform 210 could also include one or more securing elements 910 such as ridges or straps to prevent the operator's foot 121 from unintentionally disengaging from the foot platform 210 . It will be appreciated that the securing elements 910 can take many equivalent forms, such as baskets, clips, bumps, cleats, or the like. In addition, index lines (not shown) could be incorporated into the foot link 205 to facilitate more accurate and repeatable positioning of the foot platforms 210 relative to the first end of the foot link 205 . [0069] There are additional ways to create a repeatable adjustable interface between the foot platforms 210 and foot links 205 . For example, a repeatable interface could also be created by a series of mounting holes in the foot links 205 and/or the foot platforms 210 that allow for different mounting positions of the foot platform 210 along the foot link 205 . [0070] FIG. 9B depicts an alternative method for enabling the operator to repeatably change the position of his or her foot relative to the first end of each foot link 205 . In this embodiment, the foot platform 210 is large enough to permit the operator to change the position of his or her foot relative to the first end of the foot link 205 without moving the foot platform 210 . The foot platform 210 includes one or more foot locators 920 to enable the repeatable use of the various foot positions on the foot platform 210 . The foot locators 920 could include features such as cleats, bumps, ridges, or the like. Each foot platform 210 could also include securing elements 910 as discussed in connection with FIG. 9A . [0071] As discussed above, another method for adjusting the pedaling profile is modifying the length of the crank arms 235 . As shown in FIGS. 1 and 8 , the crank assembly 215 includes a crank extender 230 rotatably connected to the second end of the foot link 205 at the foot link bearing 220 . The crank assembly 215 also includes a crank drive arm 235 rotatably connected at the crank arm bearing 245 to a drive sprocket 240 . As shown in FIG. 2 , Circle R, shown as a dashed line, is generated by rotating the crank assembly 215 around the crank arm bearing 245 . The distance between the center of the crank arm bearing 245 and the center of the foot link bearing 220 is crank arm length C. Shortening crank arm length C will shorten the stride length A. Correspondingly, increasing crank arm length C will increase stride length A. Therefore, adjustments in crank arm length C can be made to modify stride length A to allow operators of different stature to adjust the apparatus 100 to suit their individual dimensions. [0072] There are many ways to modify the length of the crank arms 235 . FIG. 8 depicts one method for making the crank assembly 215 adjustable. This method employs a slot-bolt assembly 810 where the crank extender 230 includes a slot 270 and the crank drive arm 235 includes apertures configured to receive crank fasteners 275 that can locate the crank drive arm 235 at any position along slot 270 . The crank extender 230 can thereby telescope, or adjust its length with respect to the crank drive arm 235 . [0073] There are additional ways to make the crank assembly 215 adjustable. For example, the slot-bolt assembly 810 discussed above can be replaced by a clamp with pins that can clamp the crank extender 230 to the crank drive arm 235 at various positions. Another embodiment may make the crank assembly 215 adjustable by incorporating a series of holes in the crank extender 230 or the crank drive arm 235 , or both. In such an embodiment, the length of the crank drive 235 arms may be modified by changing which holes are used to fasten the crank extender 230 to the crank drive arm 235 . [0074] As discussed above, and again with reference to FIG. 2 , crank arm length C is a significant factor that determines major axis length A, which approximately equals the stride length of a given pedaling profile. For a rider of average height and body dimensions, as the stride length shrinks below approximately 17 inches, the rider's ability to transfer power to the apparatus 100 for purposes of acceleration and climbing becomes reduced. As a result, while embodiments with stride lengths generally less than about 17 inches may be appropriate for a small percentage of operators, the vast majority of riders will desire stride lengths longer than 17 inches to achieve sufficient pedaling efficiency. Embodiments of the apparatus 100 presented herein can accommodate stride lengths in excess of 23 inches. [0075] As the stride length increases, it may be desirable to increase the wheelbase W as shown in FIG. 2 . For a low cross-over height frame 110 , the longer the wheelbase W, the more difficult it is to maintain an appropriate level of bending stiffness, yet a wheelbase W that is significantly longer than conventional bicycles is desirable. For example, a conventional bicycle may have a wheelbase of about 40 inches, but embodiments of the present invention may have a wheelbase W that may range from about 55 inches to about 65 inches. As discussed above, embodiments of the apparatus 100 include a frame 110 having a sufficient bending stiffness to accommodate a stride length beyond 23 inches. [0076] Alternative embodiments of the apparatus 100 can incorporate additional features, such as a direct drive propulsion mechanism, adjustable guide tracks, and/or foldability. FIG. 12 depicts an embodiment of the apparatus that employs a direct drive propulsion system. In this embodiment, the crank arms 235 are connected directly to the hub 1210 by means of bearings (not shown) mounted in the frame 110 , through which passes a linkage from each crank arm 235 to the hub 1210 . This alternative embodiment alleviates the need for a chain and sprockets. This embodiment could incorporate a gearing system in the crank-to-hub-wheel linkage that could allow the rear wheel to rotate more quickly than the crank arms. Such a gearing system could provide a fixed input-output ratio, or could allow for one of a series of gears to be selected by the operator. In addition, the rear wheel 117 could be enlarged to allow the operator to achieve a greater rate of speed for each completed pedal stroke. [0077] FIG. 7 depicts a low cross-over height frame 110 with adjustable foot link guide tracks 255 . The forward end of each foot link guide track 255 is attached to a foot link guide track support 705 by the use of a rotary bearing 710 , so that the forward end of the foot link guide track 255 can rotate about the foot link guide track support 705 . Each foot link guide track support 705 is attached to its respective side of a collar 715 by the use of a bolt and low friction washers, or other suitable means. The collar 715 can be clamped to the downtube 725 at various locations by means of bolts or other fasteners. The low friction washers allow each foot link guide track support 705 to rotate about the bolt. The rearward or second end of each foot link guide track 255 is attached to the frame by the use of a rotary bearing 720 . Unclamping the collar 715 allows the operator to slide the collar 715 along the downtube 725 , thereby adjusting the angle of the foot link guide tracks 255 . As discussed below, changing the angle of the foot link guide tracks 255 modifies the elliptical pedaling profile experienced by the operator. [0078] FIGS. 13A and 13B depict an embodiment of the apparatus 100 that can be folded to facilitate transport or storage in small spaces. In this embodiment of a foldable apparatus 100 , the apparatus 100 is folded according to following procedure. First, the foot link retainer 610 on each foot link assembly 105 is released from the guide track 255 by removing a pin (not shown). Next, each foot link assembly 105 is rotated about its respective foot link bearing 220 towards the rear wheel 117 approximately one hundred eighty (180) degrees. Next, the coupling 1340 on each side of the apparatus is released. Each foot link guide track 255 is then rotated downwards about guide track pivot 1330 . Next, the crank assembly 215 is rotated forward about pivot 1320 until the rear wheel 117 passes through the frame 110 . Next, each guide track 255 is rotated upwards about guide track pivot 1330 . Then the crank assembly 215 is rotated until the right crank arm 235 points to the rear, as depicted in FIG. 13B . At that point, each foot link 205 may be strapped to the adjacent crank arm extender 230 . The right foot link assembly 105 is then positioned on top of the front fork 127 and the left foot link assembly 105 is positioned on top of the axle of the rear wheel 117 . Next, the steering assembly pivot 1310 is released and the steering extender sleeve 126 is rotated rearward. The steering extender sleeve 126 is then locked in place at steering assembly pivot 1310 as depicted in FIG. 13B . Once locked, the steering extender sleeve 126 may be used as a handle to carry or help direct the path of travel for the folded apparatus 100 . FIG. 13B depicts the results of following the folding procedure described above. [0079] In addition, the apparatus 100 can include gearing. Gearing can be implemented through techniques known in the art, including a series of different sized sprockets attached to the rear wheel 117 and selected by a derailleur, or a single rear sprocket connected to a hub that contains a series of gears inside of it which enable the hub to produce a variety of input-to-output ratios. This embodiment could incorporate techniques known in the art to permit the operator to select gears. This could include mounting a shift lever on the steering mechanism 120 as is known in the art. The apparatus 100 can also include a fixed gear system with no freewheel on the rear wheel 117 . [0080] The apparatus can also include mechanisms to retard motion, such as rim or disc braking systems known in the art. These mechanisms can be located on the front and/or rear wheels. The braking mechanisms can be actuated by, for example, a hinged handle or other structure mounted on the handlebars to which the brake cables or some other mechanism are connected, as is known in the art. In addition, the apparatus can include other attributes that are commonly incorporated onto other human powered vehicles, such as reflectors, lights, bottle cages, etc. [0081] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being limitative to the means listed thereafter. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B. Moreover, the components A and B should not be limited to a specific relationship or form; instead, they can be integrated together into a single structure or can operate independently. [0082] Similarly, it is to be noticed that the term “coupled”, also used in the claims, should not be interpreted as being limitative to direct connections only. Thus, the scope of the expression “a device A coupled to a device B” should not be limited to devices or systems wherein device A is directly connected to device B. It means that there exists a path between A and B which may be a path including other devices or means. In addition, “coupled” does not necessarily mean “in a fixed position or relationship” as “coupled” may include a moveable, rotatable or other type of connection that allows relative movement between A and B. Finally, “coupled” may also include “integral” where device A and device B are fabricated as an integral component or single structure. [0083] Thus, it is seen that a bicycle is provided. One skilled in the art will appreciate that the bicycle of the present invention can be practiced by other than the above-described embodiments, which are presented in this description for purposes of illustration and not of limitation. The specification and drawings are not intended to limit the exclusionary scope of this patent document. It is noted that various equivalents for the particular embodiments discussed in this description may practice the invention as well. That is, while the bicycle has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. Accordingly, it is intended that the bicycle embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.	A bicycle that includes an elliptical pedaling motion is provided. The bicycle includes a frame, having a front wheel and a rear wheel, and a first and a second foot link guide track. A first and a second foot link, each including a foot platform and a guide track coupler that slideably couples each foot link to a respective foot link guide track and a crank assembly that is coupled to the first and second foot links and to a sprocket that is rotatably coupled to the frame. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.	1
TECHNICAL FIELD The present invention is concerned with compositions and uses of amine surfactants incorporated into crop oil concentrate (COC) adjuvants for use with various herbicides, especially glyphosate. BACKGROUND INFORMATION It is known in the art that surfactants are included in COCs. They function to emulsify the oil when diluted into water in the spray tank and can also be incorporated as wetters to help the spray solution spread on the target once it is applied. BRIEF DESCRIPTION OF THE DRAWINGS In the annexed drawings, FIG. 1 shows a 10-day field trial using materials according to the present invention; FIG. 2 shows a 10-day field trial using materials according to the present invention; FIG. 3 shows a 21-day field trial using materials according to the present invention; and FIG. 4 shows a 21-day field trial using materials according to the present invention. SUMMARY OF THE INVENTION The present invention is concerned with incorporation of surfactants with amine chemistries as both emulsifier and wetter. Surfactants with amine chemistries are known to maximize the efficacy of several herbicides, especially glyphosate. By using amine chemistry surfactants in COCs that are tank mixed with pesticides that benefit from the presence of amine chemistry surfactants, the surfactants in the COCs provide dual roles in the final spray solution. They will emulsify and wet the crop oil, and they will also increase the efficacy of the active ingredient. DETAILED DESCRIPTION The specific surfactants used include alkyl amine ethoxylates and alkyl ether amine ethoxylates. Other amine chemistry surfactants such as polyetheramine and ethylenediamine based chemistries are useful in accordance with the present invention. The aforesaid compounds have been successfully formulated in crop oil concentrates with various paraffinic oils. In addition, formulations with EXXSOL® D130 and ester solvents EXXATE® series solvents also available from Exxon are useful. A composition according to the invention can include other surfactant chemistries, other crop oils, and optionally additional formulation components known in the art. Huntsman COC-1 Component w/w % EXXSOL ® D-130 60.0 PEL 24-3 28.0 SURFONIC ® C-2 4.5 SURFONIC ® T-10 5.5 Water 2.0 Huntsman COC-2 Component w/w % EXXSOL ® D-130 60.0 PEL 24-3 30.0 SURFONIC ® PEA-25 8.0 Water 2.0 EXXSOL® D-130 is a dearomatized hydrocarbon fluid available from ExxonMobil Chemical. PE L24-3 is a phosphate ester of SURFONIC® L24-3 surfactant available from Huntsman LLC of Austin, Tex. Any phosphate esters thereof are suitable for use in the present invention. SURFONIC® C-2 is a 2-mole ethoxylate of cocoamine available from Huntsman LLC of Austin, Tex. SURFONIC® T-10 is a 10-mole ethoxylate of Tallowamine available from Huntsman LLC of Austin, Tex. SURFONIC® PEA-25 is an alkyl polyetheramine ethoxylate available from Huntsman LLC of Austin, Tex. Unexpected results of the invention include the fact that the efficacy of active ingredient is improved by choice of adjuvant surfactant chemistry formulated into companion crop oil concentrate. Efficacy is improved past expectations from crop oil alone. A field trial was performed with blinded sample numbers. A protocol summary of the field trial is given below: Evaluation of Huntsman COC's with Assure® and Roundup® Original Objective: Evaluate the performance of Huntsman crop oil concentrates compared to Agriliance HI-PER-OIL with Assure II and Roundup Original® in Roundup Ready® soybeans. Target Weeds Code Common Name Scientific Name IPOSS Morningglory Ipomoea spp. ABUTH Velvetleaf Abutilon theophrasti AMASS Pigweed Amaranthus spp. SIDSP Teaweed Sida spinosa SORVU Shattercane Sorghum bicolor SETFA Giant foxtail Setaria faberi ZEAMX Volunteer RR corn Zea mays Target Crop Code Crop Common Name GLXMA Roundup Ready ® soybean Glycine max Geographic Area/Environmental Considerations and General Comments: Overhead irrigation is not required, but should be supplied if drought conditions threaten loss of data. Insure adequate broadleaf weed distribution and density by broadcasting Roundup Ready® corn seed, morning glory, velvetleaf, pigweed and prickly sida weed seeds just before the final seedbed preparation (field cultivator and/or harrow). Plant Roundup Ready® soybeans in 30″ rows. Traditional (30″) row width is requested to allow maximum opportunity for emergence and aggressive growth of indigenous broadleaf weeds. Plot size is 4 rows by 30 feet. Arrange in RCB design with 4 replications. Apply treatments in 20 gal/A spray volume. Apply experimental treatments when most broadleaf weeds are in the 3- to 6-leaf stage. At the time of application; record the stage (number of leaves), height and density (#/sq ft or sq meter) of each broadleaf weed species that is present in sufficient density and distribution for good assessment. This data should be taken from the two center row-centers of each non-treated control plot. Assess phytotoxicity to the crop at 2, 10, and 21 days after treatment. Include a description of the injury symptom and scale used for the assessment, i.e., necrotic leaf spots assessed as percent of leaf surface afflicted, percent crop height reduction, etc. Assess percent (%) control of each weed species at 10 and 21 days after treatment. Crop yield is not measured. Treatments to be Evaluated: TABLE I Sample No. Name Form Type Rate Unit 1 Control 2 Assure II 0.88 EC 4 fl oz/A 3 Assure II 0.88 EC 4 fl oz/A HI-PER-OIL 0.5 % V/V 4 Assure II 0.88 EC 2 fl oz/A HI-PER-OIL 0.5 % V/V 5 Assure II 0.88 EC 4 fl oz/A Huntsman COC 1 0.5 % V/V 6 Assure II 0.88 EC 2 fl oz/A Huntsman COC 1 0.5 % V/V 7 Assure II 0.88 EC 4 fl oz/A Huntsman COC 2 0.5 % V/V 8 Assure II 0.88 EC 2 fl oz/A Huntsman COC 2 0.5 % V/V 9 Assure II 0.88 EC 4 fl oz/A Roundup Original 4 EC 16 fl oz/A 10 Assure II 0.88 EC 4 fl oz/A Roundup Original 4 EC 16 fl oz/A HI-PER-OIL 0.5 % V/V 11 Assure II 0.88 EC 2 fl oz/A Roundup Original 4 EC 8 fl oz/A HI-PER-OIL 0.5 % V/V 12 Assure II 0.88 EC 4 fl oz/A Roundup Original 4 EC 16 fl oz/A Huntsman COC 1 0.5 % V/V 13 Assure II 0.88 EC 2 fl oz/A Roundup Original 4 EC 8 fl oz/A Huntsman COC 1 0.5 % V/V 14 Assure II 0.88 EC 4 fl oz/A Roundup Original 4 EC 16 fl oz/A Huntsman COC 2 0.5 % V/V 15 Assure II 0.88 EC 2 fl oz/A Roundup ® Original 4 EC 8 fl oz/A Huntsman COC 2 0.5 % V/V Product quantities required for listed treatments and applications in one trial: TABLE II Amount Unit Product 44.0 ml Assure ® II 0.88 EC 51.2 ml HI-PER-OIL 51.2 ml Huntsman COC 1 51.2 ml Huntsman COC 2 88.0 ml Roundup Original ® 4 EC Calculations based on 20 gal/A spray volume, mix size=2.565 liters. Evaluation of Huntsman COCs with Assure and Roundup Original—continued Protocol Spry Sheet Reps: 4; Plots: 10 by 30 feet Spray Vol: 20 gal/ac Mix Size: 2.565 liters TABLE III Sample No. Name Form Type Rate Unit to Measure 1 Control 2 Assure II 0.88 EC 4 fl oz/A 4.0 ml 3 Assure II 0.88 EC 4 fl oz/A 4.0 ml HI-PER-OIL 0.5 % V/V 12.8 ml 4 Assure II 0.88 EC 2 fl oz/A 2.0 ml HI-PER-OIL 0.5 % V/V 12.8 ml 5 Assure II 0.88 EC 4 fl oz/A 4.0 ml Huntsman COC 1 0.5 % V/V 12.8 ml 6 Assure II 0.88 EC 2 fl oz/A 2.0 ml Huntsman COC 1 0.5 % V/V 12.8 ml 7 Assure II 0.88 EC 4 fl oz/A 4.0 ml Huntsman COC 2 0.5 % V/V 12.8 ml 8 Assure II 0.88 EC 2 fl oz/A 2.0 ml Huntsman COC 2 0.5 % V/V 12.8 ml 9 Assure II 0.88 EC 4 fl oz/A 4.0 ml Roundup 4 EC 16 fl oz/A 16.0 ml Original 10 Assure II 0.88 EC 4 fl oz/A 4.0 ml Roundup 4 EC 16 fl oz/A 16.0 ml Original HI-PER-OIL 0.5 % V/V 12.8 ml 11 Assure II 0.88 EC 2 fl oz/A 2.0 ml Roundup 4 EC 8 fl oz/A 8.0 ml Original HI-PER-OIL 0.5 % V/V 12.8 ml 12 Assure II 0.88 EC 4 fl oz/A 4.0 ml Roundup 4 EC 16 fl oz/A 16.0 ml Original Huntsman COC 1 0.5 % V/V 12.8 ml 13 Assure II 0.88 EC 2 fl oz/A 2.0 ml Roundup 4 EC 8 fl oz/A 8.0 ml Original Huntsman COC 1 0.5 % V/V 12.8 ml 14 Assure II 0.88 EC 4 fl oz/A 4.0 ml Roundup 4 EC 16 fl oz/A 16.0 ml Original Huntsman COC 2 0.5 % V/V 12.8 ml 15 Assure II 0.88 EC 2 fl oz/A 2.0 ml Roundup 4 EC 8 fl oz/A 8.0 ml Original Huntsman COC 2 0.5 % V/V 12.8 ml Assure II and Roundup Original® were the active ingredients tested. TABLE IV Weed Species Studied ZEAMX = Volunteer Roundup Ready ® field corn SORVU = shattercane ( Sorghum bicolor ) IPOSS = morningglory ( Ipomoea spp.) ABUTH = velvetleaf ( Abutilon theophrasti ) AMATU = tall waterhemp ( Amaranthus tuberculatus ) SIDSP = prickly sida [a.k.a. teaweed] ( Sida spinosa ) Results of the field trial are in the attached 10-Day and 21-Day tables: TABLE V 10 DAY Evaluation of Huntsman Surfactants with Assure on Roundup Ready Soybeans Weed Code ZEAMX SORVU IPOSS ABUTH AMATU SIDSP Crop Code GLXMA Rating Data Type PHYGEN CONTRO CONTRO CONTRO CONTRO CONTRO CONTRO Rating Unit % % % % % % % Weed Stage 7 leaf 6 leaf 9 leaf 9 leaf 9 leaf 9 leaf Trt-Eval Interval 10 DA-A 10 DA-A 10 DA-A 10 DA-A 10 DA-A 10 DA-A 10 DA-A Treatment Rate Plot Control 101 0 0 0 0 0 0 0 206 0 0 0 0 0 0 0 310 0 0 0 0 0 0 0 404 0 0 0 0 0 0 0 avg 0 0 0 0 0 0 0 Assure II 4 102 0 60 70 0 0 0 0 204 0 70 85 0 0 0 0 312 0 70 80 0 0 0 0 408 0 75 80 0 0 0 0 avg 0 69 79 0 0 0 0 Assure II 4 105 0 80 90 0 0 0 0 Huntsman 0.5 208 0 85 85 0 0 0 0 COC-1 313 0 85 90 0 0 0 0 412 0 80 85 0 0 0 0 avg 0 83 88 0 0 0 0 Assure II 2 106 0 60 80 0 0 0 0 Huntsman 0.5 207 0 80 80 0 0 0 0 COC-1 309 0 85 90 0 0 0 0 414 0 85 90 0 0 0 0 avg 0 78 85 0 0 0 0 Assure II 4 107 0 80 90 0 0 0 0 Huntsman 0.5 211 0 80 85 0 0 0 0 COC-2 308 0 85 85 0 0 0 0 415 0 80 85 0 0 0 0 avg 0 81 86 0 0 0 0 Assure II 2 108 0 70 80 0 0 0 0 Huntsman 0.5 212 0 80 90 0 0 0 0 COC-2 305 0 70 90 0 0 0 0 401 0 60 90 0 0 0 0 avg 0 70 88 0 0 0 0 Assure II 4 109 0 80 90 20 20 95 40 Roundup 16 202 0 60 90 20 20 95 70 Original ® 301 0 80 85 40 20 95 50 410 0 80 85 30 20 98 60 avg 0 75 88 28 20 96 55 Assure II 4 112 0 80 90 30 20 95 60 Roundup 16 214 0 85 85 30 30 95 40 Original ® Huntsman 0.5 311 0 80 90 20 30 95 60 406 0 75 90 25 25 95 60 avg 0 80 89 26 26 95 55 Assure II 2 113 0 80 85 20 20 95 60 Roundup 8 203 0 70 90 30 20 90 50 Original ® Huntsman 0.5 304 0 80 80 20 20 70 50 COC-1 402 0 75 90 20 20 80 30 avg 0 76 86 23 20 84 48 Assure II 4 114 0 85 90 20 20 95 50 Roundup 16 213 0 85 90 40 40 95 60 Original Huntsman 0.5 307 0 85 90 20 30 85 60 COC-2 405 0 80 90 35 30 90 60 avg 0 84 90 29 30 91 58 Assure II 2 115 0 70 90 30 20 95 40 Roundup 8 209 0 80 90 20 20 90 40 Original Huntsman 0.5 315 0 60 90 20 10 90 50 COC-2 411 0 85 85 20 20 95 50 avg 0 74 89 23 18 93 45 TABLE VI 21 DAY Evaluation of Huntsman Surfactants with Assure on Roundup Ready ® Soybeans Weed Code ZEAMX SORVU IPOSS ABUTH AMATU SIDSP Crop Code GLXMA Rating Data Type PHYGEN CONTRO CONTRO CONTRO CONTRO CONTRO CONTRO Rating Unit % % % % % % % Weed Stage 8 leaf 8 leaf 9+ leaf 9+ leaf 9+ leaf 9+ leaf Trt-Eval Interval 21 DA-A 21 DA-A 21 DA-A 21 DA-A 21 DA-A 21 DA-A 21 DA-A Treatment Rate Plot Control 101 0 0 0 0 0 0 0 206 0 0 0 0 0 0 0 310 0 0 0 0 0 0 0 404 0 0 0 0 0 0 0 avg 0 0 0 0 0 0 0 Assure II 4 102 0 90 95 0 0 0 0 204 0 100 100 0 0 0 0 312 0 92 100 0 0 0 0 408 0 100 95 0 0 0 0 avg 0 95.5 97.5 0 0 0 0 Assure II 4 105 0 100 100 0 0 0 0 Huntsman 0.5 208 0 100 100 0 0 0 0 COC-1 313 0 100 100 0 0 0 0 412 0 100 100 0 0 0 0 avg 0 100 100 0 0 0 0 Assure II 2 106 0 100 95 0 0 0 0 Huntsman 0.5 207 0 100 100 0 0 0 0 COC-1 309 0 100 100 0 0 0 0 414 0 100 100 0 0 0 0 avg 0 100 98.75 0 0 0 0 Assure II 4 107 0 100 100 0 0 0 0 Huntsman 0.5 211 0 100 100 0 0 0 0 COC-2 308 0 100 100 0 0 0 0 415 0 100 100 0 0 0 0 avg 0 100 100 0 0 0 0 Assure II 2 108 0 99 100 0 0 0 0 Huntsman 0.5 212 0 100 100 0 0 0 0 COC-2 305 0 92 100 0 0 0 0 401 0 96 99 0 0 0 0 avg 0 96.75 99.75 0 0 0 0 Assure II 4 109 0 100 100 50 50 95 60 Roundup 16 202 0 100 100 60 50 95 60 Original ® 301 0 100 100 60 40 95 50 410 0 100 100 50 40 95 50 avg 0 100 100 55 45 95 55 Assure II 4 112 0 100 100 60 60 95 50 Roundup 16 214 0 100 100 60 60 92 50 Original ® Huntsman 0.5 311 0 100 100 60 60 95 60 COC-1 406 0 100 100 60 60 90 60 avg 0 100 100 60 60 93 55 Assure II 2 113 0 100 100 50 50 90 50 Roundup 8 203 0 100 100 50 40 90 50 Original ® Huntsman 0.5 304 0 100 100 40 50 85 40 COC-1 402 0 100 100 50 50 85 50 avg 0 100 100 47.5 47.5 87.5 47.5 Assure II 4 114 0 100 100 40 40 92 60 Roundup 16 213 0 100 100 60 60 95 60 Original ® Huntsman 0.5 307 0 100 100 60 70 95 60 COC-2 405 0 100 100 65 70 85 60 avg 0 100 100 56.25 60 91.75 60 Assure II 2 115 0 100 99 50 30 95 50 Roundup 8 209 0 100 100 40 60 90 50 Original ® Huntsman 0.5 315 0 100 100 40 40 92 60 COC-2 411 0 100 100 60 50 95 50 avg 0 100 99.75 47.5 45 93 52.5 Ten-Day Conclusions for Assure w/o glyphosate: Efficacy of Assure II at full rates was improved by using COCs COC1 and COC2 on both ZEAMX and SORVU. After cutting Assure rates in half, efficacy on both ZEAMX and SORVU using COC-1 was almost retained at the full rate with COC, and was significantly above full rate w/o COC. After cutting Assure rates in half, efficacy on ZEAMX using COC-2 was slightly lower than full rate with COC, but was still above full rate w/o COC. Efficacy on SORVU using COC-2 was retained at the full rate with COC, and was significantly above full rate w/o COC. Ten-Day Conclusions for Assure with glyphosate: Data is not significantly different within individual weed species. Twenty-one-Day Conclusions for Assure w/o glyphosate: Efficacy of Assure II at full rates was improved by using both COCs on both ZEAMX and SORVU. After cutting Assure rates in half, efficacy on both ZEAMX and SORVU using both COCs was almost retained at the full rate with COC, and was above the full rate w/o COC. Twenty-one-Day Conclusions for Assure with glyphosate: On IPOSS, efficacy was slightly improved with COCs at full glyphosate rate, and only slightly less than full rate when glyphosate rate was cut in half. For ABUTH, efficacy was improved with COCs at full glyphosate rate, and equal to the full rate when glyphosate rate was cut in half. For AMATU, efficacies were not significantly different for glyphosate at full rate, glyphosate plus COCs at full rate, and COC-2 with glyphosate at half rate. Efficacy was only slightly reduced with COC-1 and glyphosate at half rate. For SIDSP, COC-2 improved efficacy over glyphosate at full rate, and matched efficacy of glyphosate at full rate w/o COC when glyphosate rate was cut in half. COC-1 matched full glyphosate efficacy at full glyphosate rate, but COC-1 efficacy at half glyphosate rate was slightly reduced. Thus, the present invention provides blend compositions comprising: a) a first surfactant which comprises an alkoxylated amine; b) a second surfactant which comprises a phosphate ester; and c) and oil phase. The invention further comprises an emulsion which comprises a blend composition as just described, in combination with water and a herbicidally-active or pesticidal ingredient. An amine surfactant according to the present invention is one or more materials selected from the group consisting of: a) one or more materials represented by the structure: in which R 1 is any C 8 -C 30 saturated, unsaturated, linear, or branched alkyl group and/or any C 8 -C 30 alkyl, alkaryl (linear or branched); R 2 is any C 2 -C 6 alkyl (linear or branched) or combinations thereof; x+y is in the range of between about 2 and 50; and Z is in the range of 0 to 10; b) one or more materials represented by the structure: in which R 1 is any C 2 to C 6 alkyl (linear or branched) group; R 2 is any C 2 to C 6 alkyl (linear or branched) or combinations thereof; and w+x+y+z is in the range of 4 to 50; c) one or more materials represented by the structure: in which R 1 is a C 8 to C 30 alkyl (saturated, unsaturated, linear or branched), and/or C 8 to C 30 alkyl, alkylaryl (linear or branched); R 2 is any C 2 to C 6 alkyl (linear or branched); and R 3 is any C 1 to C 6 alkyl (linear or branched) group; d) one or more materials represented by the structure: in which R 1 is a C 8 to C 30 alkyl (saturated, unsaturated, linear or branched), and/or C 8 to C 30 alkyl, alkylaryl (linear or branched); R 2 is any C 2 to C 6 alkyl (linear or branched); and R 3 is any C 2 to C 6 alkyl (linear or branched) or combinations thereof; and x+y is in the range of 2-50, including mixtures of any of the foregoing four. A phosphate ester surfactant according to the present invention comprises one or more materials represented by the structural formula: in which R 1 and R 2 are each independently selected from the group consisting of H, and any C 9 to C 30 alkyl (linear, branched, saturated, unsaturated or combinations thereof) condensed with 0 to 30 moles of one or more of C 2 -C 6 alkylene oxides, and/or C 8 -C 30 alkyl, alkaryl (alkyl is linear and/or branched) condensed with 0-30 moles of one or more of C 2 to C 6 alkylene oxides and/or combination of aforementioned alkoxylated alkyl and alkyl, alkaryl, subject to the proviso that both R 1 and R 2 are not both simultaneously H. Agriculturally-Active Materials As used in this specification and the appended claims, the words “agriculturally active material” means any chemical substance that: 1) when applied to a given foliage that is generally regarded as undesirable adversely affects the longevity and/or reproductive capability of such foliage; or 2) when applied to a vicinity where insects dwell adversely affects the longevity and/or reproductive capability of such insects; 3) is regarded by those skilled in the art as possessing agriculturally-beneficial properties, including insecticidal, herbicidal, fungicidal, and growth-enhancing properties. Include within this definition, without limitation, are those chemical materials such as: 2,4,5-T, Acephate, Acetamiprid, Acrinathrin, Aldicarb, Amitraz, Amitrole, Arsenic and its compounds, Bendiocarb, Benfuresate, Bensulfuron methyl, Bentazone, BHC, 2,4-D Bitertanol, Butamifos, Butylate, Cadusafos, Captafol (Difolatan), Captan, Carbaryl, Chinomethionat, Chlorfenvinphos, Chlorfluazuron, Chlorimuron ethyl, Chlormequat, Chlorobenzilate, Chlorpropham, Chlorpyrifos, Chlorthalonil, Cinmethylin, Clofentezine, Copper terephthalate trihydrate, Cyanide compounds, Cyfluthrin, Cyhalothlin, Cyhexatin, Cypermethrin, Cyproconazole, Cyromazine, Daminozide, DCIP, DDT (including DDD, DDE), Deltamethrin, Demeton, Diazinon, Dicamba, Dichlofluanid, Dichlorvos, Diclomezine, Dicofol (Kelthane), Dieldrin (including Aldrin), Diethofencarb, Difenoconazole, Difenzoquat, Diflubenzuron, Dimethipin, Dimethoate, Dimethylvinphos, Edifenphos, Endrin, EPN, EPTC, Esprocarb, Ethiofencarb, Ethofenprox, Ethoprophos, Ethoxyquin, Etobenzanide, Etrimfos, Fenarimol, Fenbutatin oxide, Fenitrothion, Fenobucarb, Fenpyroximate, Fensulfothion, Fenthion, Fenvalerate, Flucythrinate, Flufenoxuron, Fluoroimide, Flusilazole, Flusulfamide, Flutolanil, Fluvalinate, Fosetyl, Fosthiazate, Glufosinate, Glyphosate, Guthion, Halfenprox, Heptachlor (including Heptachlor epoxide), Hexaflumuron, Hexythiazox, Imazalil, Imazosulfuron, Imibenconazole, Iminoctadine, Inabenfide, Inorganic bromide, Iprodione, Isophenphos, Isoprocarb, Lead & its compounds, Lenacil, Malathion, Maleic hydrazide, MCPA (including Phenothiol), Mepanipyrim, Mephenacet, Mepronil, Methamidophos, Methiocarb, Methoprene, Methoxychlor, Metolachlor, Metribuzin, Mirex, Myclobutanil, Nitenpyram, Oxamyl, Paclobutrazol, Parathion, Parathion-methyl, Pencycuron, Pendimethalin, Permethrin, Phenthoate, Phosalone (Rubitox), Phoxim, Picloram, Pirimicarb, Pirimiphos-methyl, Pretilachlor, Prohexadione, Propamocarb, Propiconazole, Prothiofos, Pyraclofos, Pyrazoxyfen, Pyrethrins, Pyridaben, Pyridate, Pyrifenox, Pyrimidifen, Pyriproxyfen, Quinalphos, Quinclorac, Sethoxydim, Silafluofen, Tebuconazole, Tebufenozide, Tebufenpyrad, Tecloftalam, Tefluthrin, Terbufos, Thenylchlor, Thiobencarb, Thiometon, Tralomethrin, Triadimenol, Tribenuron methyl, Trichlamide, Trichlorfon, Triclofos-methyl, Tricyclazole, Triflumizole, and Vamidothion. Agricultural Adjuvants Adjuvants are chemical materials which are often employed as a component of an formulation containing one or more agriculturally active materials and which are designed to perform specific functions, including wetting, spreading, sticking, reducing evaporation, reducing volatilization, buffering, emulsifying, dispersing, reducing spray drift, and reducing foaming. No single adjuvant can perform all these functions, but different compatible adjuvants often can be combined to perform multiple functions simultaneously; thus, adjuvants are a diverse group of chemical materials. Within the meaning of the term “Adjuvants” is included any substance added to the spray tank to modify a pesticide's performance, the physical properties of the spray mixture, or both. Spray application is perhaps the weakest link in the chain of events a pesticide follows through its development process. Some researchers claim that up to 70 percent of the effectiveness of a pesticide depends on the effectiveness of the spray application. Selection of a proper adjuvant may reduce or even eliminate spray application problems associated with pesticide stability, solubility, incompatibility, suspension, foaming, drift, evaporation, volatilization, degradation, adherence, penetration, surface tension, and coverage, thereby improving overall pesticide efficiency and efficacy. Surfactant adjuvants physically alter the surface tension of a spray droplet. For a pesticide to perform its function properly, a spray droplet must be able to wet the foliage and spread out evenly over a leaf. Surfactants enlarge the area of pesticide coverage, thereby increasing the pest's exposure to the chemical. Without proper wetting and spreading, spray droplets often run off or fail to adequately cover these surfaces. Such materials enhance the absorbing, emulsifying, dispersing, spreading, sticking, wetting or penetrating properties of pesticides. Surfactants are most often used with herbicides to help a pesticide spread over and penetrate the waxy outer layer of a leaf or to penetrate through the small hairs present on a leaf surface. While surfactant adjuvants may be anionic, cationic, or non-ionic, the non-ionic surfactants are in most common usage. The “multi-purpose” non-ionic surfactants are composed of alcohols and fatty acids, have no electrical charge and are compatible with most pesticides. Certain other surfactants may be cationic (+ charge) or anionic (− charge) and are specialty adjuvants that are used in certain situations and with certain products. Anionic surfactants are mostly used with acids or salts, and are more specialized and used as dispersants and compatibility agents. Cationic surfactants are used less frequently but one group, the ethoxylated fatty amines, sometimes are used with the herbicide glyphosate. Silicone-based surfactants are increasing in popularity due to their superior spreading ability. Some of these surfactants are a blend of non-ionic surfactants (NIS) and silicone while others are entirely a silicone. The combination of a NIS and a silicone surfactant can increase absorption into a plant so that the time between application and rainfall can be shortened. There are generally two types of organo-silicone surfactants: the polyether-silicones that are soluble in water and the alkyl-silicones that are soluble in oil. Unlike polyether-silicone types, alkyl-silicone surfactants work well with oil-based sprays, such as dormant and summer oil sprays used in insect control. Alkyl-silicone-enhanced oil sprays can maximize insecticidal activity and even allow significantly lower pesticide use rates that reduce residue levels on crops. Sticker adjuvants increase the adhesion of solid particles to target surfaces. These adjuvants can decrease the amount of pesticide that washes off during irrigation or rain. Stickers also can reduce evaporation of the pesticide and some slow ultraviolet (UV) degradation of pesticides. Many adjuvants are formulated as spreader-stickers to make a general purpose product that includes a wetting agent and an adhesive. Extender adjuvants function like sticker surfactants by retaining pesticides longer on the target area, slowing volatilization, and inhibiting UV degradation. Plant penetrant surfactants have a molecular configuration that enhances penetration of some pesticides into plants. A surfactant of this type may increase penetration of a pesticide on one species of plant but not another. Systemic herbicides, auxin-type herbicides, and some translocatable fungicides can have their activity increased as a result of enhanced penetration. Compatibility agent adjuvants are especially useful when pesticides are combined with liquid fertilizers or other pesticides, particularly when the combinations are physically or chemically incompatible, such as in cases when clumps and/or uneven distribution occurs in the spray tank. A compatibility agent may eliminate problems associated with such situations. Buffers or pH modifier adjuvants are generally employed to prevent problems associated with alkaline hydrolysis of pesticides that are encountered when the pH of a pesticide exceeds about 7.0 by stabilizing the pH at a relatively constant level. Extreme pH levels in the spray mixture can cause some pesticides to break down prematurely. This is particularly true for the organophosphate insecticides but some herbicides can break down into inactive compounds in a matter of hours or minutes in alkaline situations (pH>7). For example, the insecticide Cygon (dimethoate) loses 50 percent of its pest control power in just 48 minutes when mixed in water of pH 9. At a pH of 6, however, it takes 12 hours for degradation to progress to that extent. On the other hand, sulfonyl urea (SU) herbicides tend to break down more rapidly where the pH is below 7. At low pHs, the herbicide 2,4-D is an uncharged molecule. At higher pH, 2,4-D tends to become more anionic or negatively charged which can affect its movement in the environment. Leaf coatings often have a high pH that can contribute to poor performance with certain herbicides. The use of a buffering or acidifying adjuvant can stabilize or lower the pH of a spray solution thereby improving the stability of the pesticide being used. Mineral control adjuvants are used to mask the problems associated with water hardness minerals in spray water which can diminish the effectiveness of many pesticides. Mineral ions such as calcium, magnesium, salts and carbonates are commonly found in hard water. These ions can bind with the active ingredients of some pesticides, especially the salt-formulation herbicides such as Roundup™ (glyphosate), Poast™ (sethoxydim), Pursuit™ (imazethapyr), and Liberty™ (glufosinate) resulting in poor weed control. The use of water-conditioning adjuvants gives hard water minerals something to bind with other than the herbicide. In addition, some ammonium sulfate-based adjuvants can be used to offset hard water problems. Drift retardant adjuvants improve on-target placement of pesticide spray by increasing the average droplet size, since drift is a function of droplet size with drops with diameters of 100 microns or less tending to drift away from targeted areas. Defoaming agent adjuvants are used to control the foam or frothy head often present in some spray tanks that results from the surfactant used and the type of spray tank agitation system can often can be reduced or eliminated by adding a small amount of foam inhibitor. Thickener adjuvants increase the viscosity of spray mixtures which afford control over drift or slow evaporation after the spray has been deposited on the target area. Oil-based adjuvants have been gaining in popularity especially for the control of grassy weeds. There are three types of oil-based adjuvants: crop oils, crop oil concentrates (COC) and the vegetable oils. Crop Oil adjuvants are derivative of paraffin-based petroleum oil. Crop oils are generally 95-98% oil with 1 to 2% surfactant/emulsifier. Crop oils promote the penetration of a pesticide spray either through a waxy plant cuticle or through the tough chitinous shell of insects. Crop oils may also be important in helping solubilize less water-soluble herbicides such as Poast™ (sethoxydim), Fusilade™ (fluaziprop-butyl) and atrazine. Traditional crop oils are more commonly used in insect and disease control than with herbicides. Crop oil concentrates (COC) are a blend of crop oils (80-85%) and the non-ionic surfactants (15-20%). The purpose of the non-ionic surfactant in this mixture is to emulsify the oil in the spray solution and lower the surface tension of the overall spray solution. Vegetable oils work best when their lipophilic characteristics are enhanced, and one common method of achieving this is by esterification of common seed oils such as rapeseed, soybean, and cotton. The methylated seed oils (MSO) are comparable in performance to the crop oil concentrates, in that they increase penetration of the pesticide. In addition, silicone-based MSOs are also available that take advantage of the spreading ability of the silicones and the penetrating characteristics of the MSOs. The special purpose or utility adjuvants are used to offset or correct certain conditions associated with mixing and application such as impurities in the spray solution, extreme pH levels, drift, and compatibility problems between pesticides and liquid fertilizers. These adjuvants include acidifiers, buffering agents, water conditioners, anti-foaming agents, compatibility agents, and drift control agents. Fertilizer-based adjuvants, particularly nitrogen-based liquid fertilizers, have been frequently added to spray solutions to increase herbicide activity. Research has shown that the addition of ammonium sulfate to spray mixtures enhances herbicidal activity on a number of hard-to-kill broadleaf weeds. Fertilizers containing ammonium nitrogen have increased the effectiveness of the certain polar, weak acid herbicides such as Accent™ (nicosulfuron), Banvel™ (dicamba), Blazer™ (acifluorfen-sodium), Roundup™ (glyphosate), Basagran™ (bentazon), Poast™ (sethoxydim), Pursuit™ (imazethapyr), and 2,4-D amine. Early fertilizer-based adjuvants consisted of dry (spray-grade) ammonium sulfate (AMS) at 17 lbs per 100 gallons of spray volume (2%). Studies of these adjuvants has shown that Roundup™ uptake was most pronounced when spray water contained relatively large quantities of certain hard water ions, such as calcium, sodium, and magnesium. It is thought that the ions in the fertilizer tied up the hard water ions thereby enhancing herbicidal action. Consideration must be given to the fact that although this invention has been described and disclosed in relation to certain preferred embodiments, obvious equivalent modifications and alterations thereof will become apparent to one of ordinary skill in this art upon reading and understanding this specification and the claims appended hereto. The present disclosure includes the subject matter defined by any combination of any one of the various claims appended hereto with any one or more of the remaining claims, including the incorporation of the features and/or limitations of any dependent claim, singly or in combination with features and/or limitations of any one or more of the other dependent claims, with features and/or limitations of any one or more of the independent claims, with the remaining dependent claims in their original text being read and applied to any independent claim so modified. This also includes combination of the features and/or limitations of one or more of the independent claims with the features and/or limitations of another independent claim to arrive at a modified independent claim, with the remaining dependent claims in their original text being read and applied to any independent claim so modified. Accordingly, the presently disclosed invention is intended to cover all such modifications and alterations, and is limited only by the scope of the claims which follow, in view of the foregoing and other contents of this specification.	In agricultural practice it is known to use emulsifiable oils (commonly referred to a Crop Oil Concentrates, COC) as bioefficacy enhancers for pesticides, especially herbicides. Cationic surfactants are widely known to be particularly effective bio-active enhancers for herbicides, especially for glyphosate-type herbicides. The present invention includes two novel aspects: 1) While the vast majority of COCs are petroleum-based paraffinic oils or esterified seed oils, this invention embodies a new oil phase, a hydrocarbon oil such exemplified by EXXON-MOBIL'S D-130, which when combined with the surfactants described herein, exhibits surprising enhancement of herbicidal activity in field tests; and 2) COC's are designed to form stable emulsions in water. The combination of cationic surfactants and phosphate esters in this invention not only form very stable emulsions in water, but, surprisingly, also form extremely stable emulsions in concentrated liquid fertilizers, including 32-0-0 fertilizer.	0
FIELD OF THE INVENTION The invention provides a process for preparing (4-nitrosophenyl)-phenylhydroxylamine which, as an intermediate in the preparation of 4-aminodiphenylamine (4-ADPA), can be used as an important feedstock for the synthesis of antioxidants and stabilizers in the rubber and polymer industry (Kirk-Othmer, Encyclopedia of Chemical Technology, 4th edition, 1992, vol. 3, pages 424-456; Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, vol. A3, 1985, pages 91-111). BACKGROUND OF THE INVENTION Syntheses for (4-nitrosophenyl)phenylhydroxylamine, which have been previously described, have started only from nitrosobenzene. Nitrosobenzene is dimerized in strongly acid medium to give (4-nitrosophenyl)phenylhydroxylamine when the following acids are used, such as sulfuric acid (Bamberger et al., Chem. Ber., 31 (1898), 1513; DE 2020043), peroxytrifluoroacetic acid (Boyer, J. Org. Chem. 24 (1959) 2038), hydrofluoric acid (Wiechert, Z. Chem. 15 (1955) 21; DE 1147237), sulfonic acids, perchloric acid, trifluoroacetic acid (DE 2703919) and Lewis acids such as, for example, BF 3 xOEt 2 (EP 9267). (4-nitrosophenyl)phenylhydroxylamine is also formed as a secondary product when reacting nitrosobenzene with alcoholates as bases, (Aurich et al., Liebigs Ann. Chem. (1981), 1271-1281; Hutton, Waters, J. Chem. Soc. (B) (1968) 191). A serious disadvantage of the processes described is that they use nitrosobenzene as a starting material and this cannot be prepared in an economically viable manner, in particular, from inexpensive nitrobenzene, on an industrial scale (Kochetova, Klyuyev, Petroleum Chemistry, vol. 37, (1997), 414-421). It was, therefore, desirable to develop a process for preparing (4-nitrosophenyl)phenylhydroxylamine which uses a more cost-effective and less expensive starting material than nitrosobenzene. SUMMARY OF THE INVENTION The present invention provides a process for preparing (4-nitrpsophenyl)phenylhydroxylamine which is characterized in that nitrobenzene is reacted with hydroxide and/or oxide group-containing bases, optionally in the presence of a solvent, at temperatures of 20 to 180° C. and pressures of 0.1 to 10 bar. DETAILED DESCRIPTION OF THE INVENTION Hydroxide and/or oxide group-containing bases which are suitable for use in the process according to the present invention are inorganic bases such as alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides and the corresponding hydroxides and oxides of the elements 58 to 71 in the Periodic System of the Elements (according to IUPAC, new). The following may be mentioned by way of example: the oxides and hydroxides of sodium, potassium, lithium, cesium, magnesium, calcium, barium, lanthanum and/or cerium, preferably the oxides and hydroxides of lithium, sodium, potassium cesium, most preferably, cesium hydroxide. Furthermore, organic bases such as, for example, quaternary alkylammonium hydroxides (NR 4 + OH - with R representing, independently of each other, alkyl, aryl or aralkyl groups with 1 to 7 carbon atoms) are also suitable. The following examples may be mentioned: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltributylammonium hydroxide, methyltripropylammonium hydroxide, methyltriethylammonium hydroxide, trimethylbenzylammonium hydroxide. Tetrapropylammonium hydroxide and tetrabutylammonium hydroxide are preferred. Tetramethylammonium hydroxide is most preferred. Obviously, it is also possible to use the bases as mixtures with each other. The most beneficial mixing ratio can easily be determined each time in appropriate preliminary trials. Furthermore, it is possible to use the inorganic bases in combination with phase transfer catalysts. Suitable phase transfer catalysts are described, for example, in W. E. Keller, Fluka-Kompendium, vol. 1,2,3, Georg Thieme Verlag, Stuttgart 1986, 1987, 1992. For example, the previously mentioned bases may be used together with a crown ether such as 18-crown-6 or quaternary ammonium compounds. The bases to be used according to the present invention may have a water content of up to 6 mol of water; in a preferred embodiment, up to 3 mol of water; and in a most preferred embodiment, up to 2.5 mol of water, with respect to one mol of base. A higher water content generally impairs the yields. According to the present invention, bases may be added in the solid form, as molten materials or as a solution or mixture in a solvent or solvent mixture. According to the present invention, the bases are used in amounts of 0.01 to 3, preferably 0.1 to 2 equivalents per mol of nitrobenzene. Suitable solvents are aromatic hydrocarbons with 6 to 20 carbon atoms, linear or cyclic ethers with up to 5 oxygen atoms and 2 to 16 carbon atoms, aromatic halogenated hydrocarbons with 6 to 20 carbon atoms and amides with 1 to 10 carbon atoms. Obviously, the solvents mentioned may be used as mixtures with each other. The following may be mentioned, in particular, as suitable solvents: benzene, toluene, xylene, tert.-butyl methyl ether, tert.-amyl methyl ether, diisopropyl ether, diethylene glycol dimethyl ether, glycol dimethyl ether, dioxan, tetrahydrofuran, diamyl ether, chlorobenzene, dichlorobenzene, dimethylformamide, dimethylacetamide and N-methylpyrrolidinone. The following are preferably used: toluene, xylene, glycol dimethyl ether, tert.-butyl methyl ether, diisopropyl ether, diethylene glycol dimethyl ether, most preferably tert.-butyl methyl ether and toluene. The amount of solvent is not a critical factor in the process according to the present invention. The most appropriate amount can also easily be determined in appropriate preliminary tests. The amount of solvent depends, in particular, on the reaction temperature and on the type and amounts of bases and catalysts used. Generally, the solvent is used in amounts of 1 to 99 wt. %, preferably 5 to 95 wt. %, and most preferably 15 to 90 wt. %, with respect to the total amount of reaction mixture. The reaction temperatures for the process according to the present invention are preferably 20 to 180° C., and most preferably from 50 to 150° C. It is an advantage to control the concentration of protic material, such as e.g. water, which is achieved by using water-bonding reagents such as molecular sieves, KOH, P 2 O 5 , but also by stripping with an inert gas, by distilling off water under e.g. reduced pressure and preferably by azeotropic distillation. It is also an advantage to minimize the concentration of oxygen in the reaction solution, which can be achieved by degassing the solutions and by a conventional protective gas technique using e.g. nitrogen and/or argon. Isolation of the desired (4-nitrosophenyl)phenylhydroxylamine from the reaction mixture takes place by crystallization, optionally after previous filtration or neutralization. However, it is also possible to use the reaction mixture obtained for further reaction without any further working-up procedures. The reaction mixture obtained is suitable, in particular, for preparing 4-ADPA in the presence of hydrogen and hydrogenation catalysts. 4-ADPA can be used in the usual manner for the preparation of anti-ageing compounds, useful preferably in the rubber industry. The invention is further illustrated but is not intended to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified. EXAMPLES Example 1 123 g of nitrobenzene in 300 g of di-n-butyl ether are initially introduced. 140 g of tetramethylammonium hydroxide dihydrate are added to this solution. The reaction mixture is heated at 75-80° C. for four hours under an inert gas atmosphere. Using GC (internal standard) and HPLC (external standard), a selectivity of 16% for (4-nitrosophenyl)phenyl-hydroxylamine is determined at a conversion of 78%. After adding 50 ml of water, the phases separate. The aqueous phase is adjusted to pH=1 by adding 25% strength sulfuric acid and is extracted several times with methylene chloride. After concentrating by evaporation under vacuum, a residue of 85 g remains with a (4-nitrosophenyl)phenylhydroxylamine content of 14% (HPLC; external standard). This corresponds to a selectivity of 16%. Example 2 7.4 g of tetramethylammonium hydroxide dihydrate and 10 g of molecular sieve were initially introduced into 50 ml of di-n-butyl ether. This mixture was heated to 80° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 5 hours at this temperature. After adding 50 ml of water, 17% of (4-nitrosophenyl)phenyl-hydroxylamine was determined in the polar phase at 98% conversion, using HPLC. Example 3 7.4 g of tetramethylammonium hydroxide dihydrate were initially introduced into 50 ml of triethylamine. This mixture was heated to 80° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 5 hours at this temperature. After adding 50 ml of water, 14% of (4-nitrosophenyl)phenylhydroxylamine was determined in the polar phase at 84% conversion, using HPLC. Example 4 22.2 g of tetramethylammonium hydroxide dihydrate were initially introduced into 50 ml of tert.-amyl methyl ether. This mixture was heated to 80° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 2 hours at this temperature. After adding 50 ml of water, 9% of (4-nitrosophenyl)-phenylhydroxylamine was determined in the polar phase at 100% conversion, using HPLC. Example 5 7.4 g of tetramethylammonium hydroxide dihydrate and 10 g of molecular sieve were initially introduced into 50 ml of tetrahydrofuran. This mixture was heated to reflux point under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was boiled under reflux for 5 hours. After adding 50 ml of water, 8% of (4-nitrosophenyl)phenylhydroxyl-amine was determined in the polar phase at 77% conversion, using HPLC. Example 6 3.7 g of tetramethylammonium hydroxide dihydrate and 10 g of molecular sieve were initially introduced into 50 ml of di-n-butyl ether. This mixture was heated to 80° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 3 hours at this temperature. After adding 50 ml of water, 5% of (4-nitrosophenyl)phenyl-hydroxylamine was determined in the polar phase at 75% conversion, using HPLC. Example 7 7.4 g of tetramethylammonium hydroxide dihydrate and 10 g of molecular sieve were initially introduced into 50 ml of tert.-butyl methyl ether. This mixture was heated to reflux point under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was boiled under reflux for 3 hours. After adding 50 ml of water, 7% of (4-nitroso-phenyl)phenylhydroxylamine was determined in the polar phase at 65% conversion, using HPLC. Example 8 7.4 g of tetramethylammonium hydroxide dihydrate and 10 g of molecular sieve were initially introduced into 50 ml of toluene. This mixture was heated to 80° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 5 hours at this temperature. After adding 50 ml of water, 8% of (4-nitrpsophenyl)phenylhydroxylamine was determined in the polar phase at 95% conversion, using HPLC. Example 9 7.4 g of tetramethylammonium hydroxide dihydrate and 10 g of molecular sieve were initially introduced into 50 ml of di-n-butyl ether. This mixture was heated to 65° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 2 hours at this temperature. After adding 50 ml of water, 12% of (4-nitrosophenyl)phenyl-hydroxylamine was determined in the polar phase at 88% conversion, using HPLC. Example 10 7.2 g of tetramethylammonium hydroxide dihydrate were initially introduced into 50 ml of tert.-amyl methyl ether. This mixture was heated to 80° C. under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 3 hours at this temperature. After adding 50 ml of water, 12% of (4-nitrosophenyl)phenylhydroxylamine was determined in the polar phase at 76% conversion, using HPLC. Example 11 7.5 g of tetramethylammonium hydroxide dihydrate were initially introduced into a mixture of 50 ml of di-n-butyl ether and 10 ml of triethylamine. This mixture was heated to 80° C. (bath temperature) under an inert gas atmosphere, 6.2 g of nitrobenzene were added and the mixture was stirred for 5 hours at this temperature. After adding 25 ml of water, 15% of (4-nitrosophenyl)phenylhydroxylamine was determined in the polar phase at 79% conversion, using HPLC. Example 12 61.6 g of tetramethylammonium hydroxide dihydrate were initially introduced into 48 ml of tert.-amyl methyl ether. This mixture was heated to 80° C. under an inert gas atmosphere, 63.6 g of nitrobenzene were added and the mixture was stirred for 4.5 hours at this temperature. 6% of (4-nitrosophenyl)-phenylhydroxylamine was determined in the polar phase at 67% conversion, using HPLC. Example 13 85 g of the residue from example 1 are dissolved in 200 g of isopropanol and hydrogenated at 50° C. under 30 bar of H 2 until no more hydrogen is taken up, after adding 5 g of Pd/C (5% strength). After filtering off the catalyst, 0.055 mol of 4-ADPA are detected in the filtrate (GC, internal standard). This corresponds to a selectivity of 92% with respect to (4-nitrosophenyl)phenylhydroxylamine. Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.	The present invention provides a process for preparing (4-nitroso-phenyl)phenyl-hydroxylamine which is characterized in that nitrobenzene is reacted in the presence of hydroxide and/or oxide-containing bases, optionally in the presence of solvents, at temperatures of 20 to 180° C. and pressures of 0.1 to 10 bar. The process according to the invention has the particular advantage that it uses inexpensive and cost-effective nitrobenzene as starting material instead of the nitrosobenzene conventionally used hitherto.	2
CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. provisional patent application Ser. No. 60/790,802, filed Apr. 11, 2006, which is incorporated herein by reference. FIELD The present invention relates to telemetry apparatus and methods, and more particularly to acoustic telemetry apparatus and methods used in the oil and gas industry. BACKGROUND There are numerous methods, techniques and innovations designed to improve the oil and gas drilling process. Many of these involve feedback of various measured downhole parameters that are communicated to the surface to enable the driller to more efficiently, safely or economically drill the well. For example, U.S. Pat. No. 6,968,909 to Aldred et al. teaches a control system that combines measurement of downhole conditions with certain aspects of the operation of the drillstring. These downhole measurements are conveyed to the surface by well-known standard telemetry methods where they are used to update a surface equipment control system that then changes operation parameters. Closed loop two-way communication techniques like this, however, rely on the adequate detection at the surface of the telemetered parameters. It is standard in the drilling industry to control certain parameters of the downhole telemetry transmitter by downlinking appropriate commands from the surface. For example, changing the downhole drilling fluid pressure in a prescribed manner by changing the flow rate of the drilling fluid and subsequently monitoring this by a downhole pressure gauge is a common technique. Problems associated with this and similar downlinking techniques include false detection, slowing of the drilling process and the need to include human intervention in the process. There are at present two standard telemetry techniques in common use—data conveyed via pressure waves in the drilling fluid and data conveyed via very low frequency electromagnetic waves, both originating at a downhole transmitter. Another telemetry technique beginning to emerge in the drilling arena is to convey the data via acoustic waves travelling along the drillpipe. All three technologies suffer from noise associated with the drilling operation, and all three similarly suffer signal attenuation at the surface as the well bore increases in length. These problems are illustrated herein by discussing some of the issues associated with the utilization of acoustic transmissions to transfer data from downhole to an acoustic receiver rig at the surface. The design of acoustic systems for static production wells has been reasonably successful, as each system can be modified within economic constraints to suit these relatively long-lived applications. The application of acoustic telemetry in the plethora of individually differing real-time drilling situations, however, is less widespread. This is primarily due to it presently being an emerging technology and because of specific problems related to the increased in-band noise due to certain drilling operations, and unwanted acoustic wave reflections associated with downhole components such as the bottom-hole assembly (or “BHA”), typically attached to the end of the drillstring. The problem of communication through drillpipe is further complicated by the fact that drillpipe has heavier tool joints than production tubing, resulting in broader stopbands; this entails relatively less available acoustic passband spectrum, making the problems of noise and signal distortion even more severe. As the well is drilled and the amount of drillpipe increases there is a general degradation of the available acoustic passband properties, primarily through two effects: the non-identical dimensions of the drillpipes due to manufacturing tolerances and recuts of tool joints will narrow and distort the acoustic passband; the acoustic signal attenuation increase is directly related to the number of drillpipes. The amount of drillpipe in the well is directly related to the ‘measured depth’ (MD), in contrast to the ‘true vertical depth’ (TVD), i.e. the vertical depth used in calculating the hydrostatic pressure in a well. Attenuation is also a function of the amount of wall contact with the drillpipe because this contact provides a means of extracting energy from acoustic waves travelling along the pipe. Typical attenuation values may range from 12 dB to 35 dB per kilometer. Noise from many sources must be dealt with. For example, the drill bit, mud motor and the BHA and pipe all create acoustic noise, particularly when drilling. The downhole noise amplitude generally increases as rotation speed and/or the drilling rate of penetration increases. On the surface, noise originates from virtually all moving parts of the rig. Dominant noise sources include diesel generators, rotary tables, top drives, pumps and centrifuges. Thus it is evident that channel issues and noise problems will increase with the measured depth, drilling rate and rotary speed. In summary, the challenges to be met for acoustic telemetry in drilling wells include: Restricted channel bandwidth due to the drillstring passband structure (see U.S. Pat. No. 5,128,901 to Drumheller) Channel centre shifts Dynamically changing channel properties Downhole noise due to drillpipe movements Downhole noise due to mud motor and/or drill bit activity Surface noise due to rig components such as diesel generators, rotating tables, and top drives Channel impairments generally degrade the signal's amplitude and/or phase integrity, while noise impedes the receiver's ability to detect what signal there is. A very simple metric that is used in these circumstances is the signal-to-noise ratio (SNR). Maximizing the SNR is a telemetry objective. Certain embodiments of the present invention teach a novel means of enabling the automatic control of various transmitter parameters so as to maintain the SNR available at surface at or above a minimum achievable and predetermined threshold in the acoustic drilling telemetry environment. It can equally be applied to the other major telemetry means indicated herein as they have similar SNR issues resulting from their own associated telemetry channel impairments. SUMMARY It is an object of certain embodiments of the present invention to optimize the telemetry performance of a simple one-way (subsurface to surface) telemetry link from the downhole transmitter through the appropriate channel to a receiver located on the rig at surface. For convenience the telemetry performance is defined simply as the ability of the surface receiver to decode the telemetered parameters detected at surface in the presence of noise. It is evident that the noise sources as discussed are present to an extent that depends on the immediate needs of the rig crew actually drilling and steering the well. It is also evident that the signal attenuation will increase as the well is drilled, bringing more drillpipe and more wall contact. The present invention is directed to enhancing the received signal in order to offset the reduction in SNR as the MD increases by implementing one or more of the following exemplary actions, which are for illustrative purposes only: signal repetition reduced data rate increased signal length increase the signal's frequency span increase the transmitter's output level Undertaking these actions is not novel in itself; it is the means by which these techniques are employed, as explained below. If the transmitter module had access to the MD of the drillpipe it could be programmed to undertake certain of the SNR improvements at specified MDs. In the case of acoustic telemetry for instance, at each 500 m increment a combination of signal increase and chirp length could be implemented. Because the telemetry system to which the present invention beneficially but not exclusively applies is for one-way systems, the downhole tool may not be in receipt of this information from the surface, and thus an inferential method would be utilized. The basis for the present invention is to infer the approximate measured depth (i.e. the total length of the drill pipe) by measuring downhole pressure. Pressure values are readily available by the use of one or more pressure sensors that can sample bore pressure, annular pressure or both. The majority of downhole telemetry tools incorporate at least one pressure sensor as this is an important parameter in safely drilling a well. Once the pressure is determined the most straightforward inferential method is to utilize a look-up table that is configured around particular parameters of the well being drilled. According to one aspect, there is provided a method and apparatus for enhancing downhole telemetry performance. The method comprises: measuring downhole pressure at a specified location; inferring a measured depth from the measured downhole pressure; and modifying a downhole telemetry signal at one or more measured depths in order to offset the estimated signal-to-noise ratio reduction with increasing measured depth. The apparatus comprises: a pressure sensor for measuring downhole pressure at a specified location; a telemetry signal transmitter; and a processor with a memory having recorded thereon steps and instructions for carrying out the method. The measured depth calculation becomes more complicated when the well deviates from vertical. This deviation can be assessed by the use of a ‘direction and inclination’ sensor (D&I) commonly deployed downhole. The issue is that even though the angle in the hole is known, prior to this invention the downhole tool is not able to assess its distance along the deviated section(s) of the well without information being relayed from the surface. Our invention provides an inferential method of estimating MD for all sections of the well. The step of inferring can be performed even when the specified location is in a horizontal section of a well bore, comprising measured downhole pressure(s) with a form of a previously-calculated equivalent circulating density estimate for specified locations, with preferably, although necessarily a correlation of D&I angle of well trajectory measurements. The pressure sensor can usually be configured to measure annulus pressure or bore pressure or both. The step of inferring a measured depth can comprise associating a measured annulus pressure to a predicted annulus pressure then selecting a measured depth corresponding to the associated predicted annulus pressure. The method can be performed in a drill string having a bottom hole assembly with no repeater. In such case the specified location is the location of the bottom hole assembly in a well bore. Alternatively, the method can be performed in a drill string having a bottom hole assembly and at least one repeater; in such case the specified location is the location of the repeater closest to the surface, and the step of inferring measured depth comprises inferring a first measured depth between the specified location and the surface, incorporating a predetermined second measured depth between the specified location and the bottom hole assembly, then combining the first and second measured depths. BRIEF DESCRIPTION OF THE DRAWINGS The following drawings illustrate the principles of the present invention and an exemplary embodiment thereof: FIG. 1 is schematic representation of a rig 1 and the profile 2 of a vertical well. FIG. 2 further shows the profile 3 of a deviated well. FIG. 3 further shows the profile 4 of a typical horizontal well. FIG. 4 further shows the profile 5 of a typical extended reach well. FIG. 5 is a graph showing a consolidation of the overall drilling industry preferences when drilling wells that incorporate non-vertical sections. FIG. 6 a is a schematic representation of a rig with a depiction of a downhole telemetry tool. FIG. 6 b is a schematic representation of a rig with a depiction of a downhole telemetry tool with the addition of a repeater telemetry tool. FIG. 6 c is a schematic representation of the representation depicted in FIG. 6 b but indicating a situation where drilling has progressed. DETAILED DESCRIPTION It is apparent from FIG. 1 that the MD is readily predicted by the downhole tool by measuring the downhole hydrostatic pressure P hs once the fluid density is known or assumed, as predicted by equation 1: P hs =ρgh [1] where ρ=drilling fluid density g=acceleration due to gravity h=vertical height of the fluid column It is normal that during the course of drilling a well the density ρ is deliberately changed. Furthermore ρ can change depending on whether the fluid is being pumped or is stationary. It can also change depending on the volume and type of cuttings and how they are held in suspension. This effect leads to consideration of an equivalent circulating density calculation (ECD, equation 2, following) that is utilized for the control and safety of modern wells. The present invention as applied to reasonably vertical wells is to utilize the pressure readings when the flow is static. At the well planning stage it will be known to an adequate degree of accuracy how the well profile and the addition of materials to the drilling fluid will affect the downhole pressure P hs . It does not matter whether the sampled pressure is that in the bore or in the annulus—they are almost the same under static conditions. Thus a look-up table that equates pressure P hs to MD can be constructed, where it is assumed that h is equivalent to MD. It is then apparent that relatively coarse changes in MD (for example, increments of 500 m) can be inferred by assessing P hs that in turn can implement changes in the transmitted signal in a way that increases SNR and thus will improve detection and decoding ability of the surface equipment. Such a look-up table or similar can be readily built by incorporating appropriate features of the planned well such as drilling fluid flow rate, drilling fluid density, drilling fluid viscosity, well profile, bottom hole assembly component geometry, drillpipe geometry, and indications as to whether the fluid is flowing or stationary. If the value of ρ is changed, as noted above, this effect can easily be accommodated by planned incremental changes for ρ in the look-up table that are applied to the successively deeper sections of the well. For instance if the static pressure changes in excess of a given threshold between one predetermined pressure in the table and the next, the inference is that the increase is due primarily to a planned increase in mud density and not simply an increase in TVD. FIG. 2 adds a minor complication in that once a given depth is encountered the well is steered away from vertical at some predetermined angle, as could conveniently be assessed by the D&I package, although our invention does not require this as the angular deviation may be also inferred from simple static pressure changes. The correspondence of pressure to MD is modified in an obvious manner using simple geometry. It is now apparent that the look-up table as described is a viable method of determining MD in deviated wells. However it is known that in the art that FIG. 2 is an oversimplification of practical wells because it is not usually possible to drill a well in a perfectly straight line for any significant distance. The driller's job includes the need to continually correct the profile by making relatively small steering adjustments. In most instances these corrections are small enough that the method as described herein will remain substantially valid. FIG. 3 adds an apparently major obstacle to inference of MD because the profile 4 contains a section of horizontal well, thus rendering equation 1 inappropriate for this section. In practical drilling applications horizontal sections are included in a class of wells called ‘extended reach drilling’ (ERD) wells, as depicted in FIG. 4 . The profile 5 can be typical of a directional well containing not only horizontal sections but also generally positive sloped sections and generally negative sloped sections. This is because in many circumstances it is necessary to follow a target formation that undulates in TVD. In a proportion of these wells the generally horizontal section is relatively short compared to the vertical section. In these cases it would be adequate to use the look-up table to maximize the SNR improvements for the whole of the horizontal section. In many ERD wells, however, the generally horizontal drilled section is equal to or greater than the length of the vertical section. This is indicated in FIG. 5 , where the X-axis 6 depicts TVD in meters and the Y-axis 7 depicts the horizontal displacement (departure) from vertical in meters. The hatched section 8 in this figure consolidates and presents the industry well drilling practice for these parameters over the last 40 years. Although it is not obvious from FIG. 5 , roughly 67% of ERD wells have a departure from vertical greater than their TVD. Because the well types typified by FIGS. 3 and 4 are a very significant fraction of the total number of wells drilled, incorporating another technique is necessary for the MD estimation procedure. According to the present invention, the pressure can also be measured under flow (dynamic) conditions and use is then made of a prediction of ECD versus MD. A greatly simplified explanation of this and its relevance to the present invention is as follows. The annular pressure AP due to dynamic flow increases with flow rate and pipe length (i.e. MD) because of factors such as the increase in friction both inside and outside the drillpipe. AP also usually increases to a relatively small extent (a few percent) with cuttings in the annulus because they restrict flow (particularly at the tool joint sections) and also increase in net fluid density when the cuttings are in suspension. Because of the generally small effect of cutting, they will be neglected hereon as they do not modify the principles embodied in this invention. As the AP value changes it also equally changes the bore (internal pipe) pressure because the drilling fluid flows continuously from bore to annulus. Therefore we could equivalently measure the bore pressure if that happened to be more convenient, or indeed, as necessitated by the type of pressure gauge in the BHA. The simplest form of the calculation of ECD is (for instance see Formulas and Calculations for Drilling, Production and Workover, 2'nd edition; publisher: Butterworth-Heinemann; 2002, ISBN: 0750674520): ECD=MW+(AP/(0.052×TVD) [2] where MW=drilling fluid (mud) weight (pounds per gallon) AP=annulus pressure drop (psi) between surface and the depth at TVD TVD=true vertical depth (feet) Sophisticated algorithms are readily available to quantify AP in the well planning stage and thus predict ECD at any position along the planned well trajectory by taking into account the many variables that modify the predicted value of ECD. The present state of the art is that predicted ECD compared to actual ECD can be accurate to within ˜5% for a calibrated model, or ˜10% or more for a non-calibrated model. We take advantage of this standard calculation to incorporate the pressure drop in excess of the hydrostatic drop (equation 1) and incorporate the total pressure drop expected at each stage of the well's progress into the look-up table, the ECD-related calculations being particularly pertinent for the stages where deviations from vertical are significant. This procedure merely complicates the table (or similar) entries, and requires that certain drillstring parameters are taken into the flow condition calculations. We point out that we do not actually need to calculate ECD; we need only to compute the relationship of AP to MD, this forming a part of the derived ECD calculations commonly utilized in the drilling industry. The AP value we use is directly associated with length of drillpipe along the whole length of the well bore (i.e. MD) and the BHA geometry. We are assuming in these cases that the planned flow rate is followed in practice. If it is not, an error proportional to the square of the flow velocity is introduced in the pressure p calculation, as would be given in the simplest form (laminar flow) by Daniel Bernoulli's hydrodynamic equation (see for instance H. Lamb, Hydrodynamics, 6th ed., Cambridge University Press, 1953, pp. 20-25): p+ ½ ρv 2 +ρgΔh =constant [3] where v=fluid velocity Δh=vertical height change over which pressure p is measured If the BHA pressure gauge has both bore and annulus pressure measuring capabilities, one can make use of equation 3 by measuring the differential pressure (i.e. bore—annulus) that is normally sensed across the mud motor and drill bit, thereby estimating the velocity v. Either a calculation or a calibration can be used to link v to p. This value of v can be used to modify the tabular entries to a specific set of flow velocities, and thereby obtain a more accurate estimate of MD, as indicated below. Once v is calculated in this manner (or assumed from preset table entries) then the appropriate annular pressure AP (equation 2) can be associated with a specific flow velocity. The next step is to recognise that the total dynamic annular or bore pressure P tool as measured by the downhole BHA tool in these types of wells is given by: P tool =P hs +AP [4] where we have separated the hydrostatic head component of pressure (P hs ) and the hydrodynamic pressure drop associated only with flow in equation 4. Thus in a well with significant horizontal sections a combined measure of static and a dynamic pressures can be used to isolate AP. AP has already been calculated and is in tabular form in a look-up table (or similar) in the downhole tool. Because AP is a function of v and if v is known, it is now obvious that a reasonable estimate of AP can be mapped directly to MD. If v is not measured the assumed value of v is utilized in a simpler table, with a somewhat lesser degree of accuracy in MD. Either way, because we use MD in a coarse incremental fashion (e.g. increments of ˜500 m) the changes to transmission parameters that modify SNR will not be significantly suboptimal. The methods described herein can also beneficially apply to drilling circumstances where downlinking to the telemetry tool is possible. This is because the automatic nature of the telemetry changes associated with sampling downhole pressure makes it unnecessary for surface control or intervention to be applied to the task of ensuring adequate received SNR under most drilling conditions. Furthermore, the methods described herein can also beneficially apply to drilling circumstances where a telemetry repeater tool is also included in the drillstring. FIG. 6 a depicts the conventional start of a deviated well where the BHA 10 (including drilling means and telemetry tool) is separated from the rig 1 by a length (MD) of drillpipe 9 . The invention as previously discussed applies to this stage. The next stage is to insert a repeater 11 as shown in FIG. 6 b . The amount of drillpipe between repeater 11 and BHA has now a planned increase 12 that is intended to enable communications over approximately twice the distance that limits a non-repeater circumstance. Because it is known in the well planning stage that a repeater would be inserted at a specific MD, the look-up table or similar means would now fix the appropriate telemetry parameters to values suitable for adequate communications from the BHA telemetry device 10 to the repeater 11 . The invention now applies to control of the appropriate telemetry parameters associated with the repeater 11 , as shown in FIG. 6 c . As the well progresses the drillpipe length 13 between the repeater and the rig increases, and SNR communication to the rig is modified by the look-up table or similar within the repeater, enabling efficient communication as before. In summary, it is possible for the tool to make an approximate inferred estimate of its MD by making use of standard downhole sensors and assessing the downhole pressure. Thus, the tool could be programmed to automatically adjust certain of its acoustic transmitted parameters such that it could compensate for the surface reduction in SNR caused by increasing attenuation due to increasing MD. The present invention therefore provides a method by which tool telemetry decoding performance may be maintained at or above a specified threshold with increasing well length without the need to communicate to the tool from the surface. This method also includes the circumstances where one or more repeaters are incorporated, as would now be understood by one skilled in the art.	A method whereby a downhole drilling transmission device that communicates to the surface automatically modifies its transmission parameters in order that it substantially improves its ability to adequately communicate with a surface receiver despite increasing signal attenuation between the two as the length of drillpipe increases. This utilizes a simple measure of localized downhole pressure that then relies upon a look-up table or similar that provides a correspondence between said pressure and measured depth. Such a look-up table or similar can be readily built by incorporating appropriate features of the planned well such as drilling fluid flow rate, drilling fluid density, drilling fluid viscosity, well profile, bottom hole assembly component geometry, drillpipe geometry, and indications as to whether the fluid is flowing or stationary. Upon determining the measured depth the tool then can attempt to modify or augment appropriate telemetry parameters in order to keep the signal received at surface within required parameters, thus offsetting the degradation due to increasing attenuation.	4
[0001] This application claims the benefit of U.S. Provisional Application No. 60/602,741, filed Aug. 17, 2004. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to endoscopy, and more particularly to hysteroscope sheaths with improved flow characteristics. [0004] 2. Discussion of Prior Art [0005] Endoscope sheaths or tubes having a visual channel for optics, possibly an instrument channel, and inflow and outflow channels for irrigating or other liquids are well-known. Diagnostic applications include Dysfunctional Uterine Bleeding (DUB) and Post-Menopausal Bleeding (PMB). Interventional (operative) applications include polypectomy, sterilization, synechiolysis, and foreign object removal. On the one hand, it is desirable to minimize the diameter of the sheath to reduce the invasive effect of its use in patients. On the other hand minimizing the diameter also reduces the capacity of the sheath to deliver and remove liquids. FIG. 1 is a cross-section of a conventional concentric-channel sheath for a diagnostic probe. Concentric sheaths cause a significant resistance to flow due to the large contact surface between the sheath and the fluid. [0006] There remains therefore a need for an endoscopic sheath having an improved capacity for transporting liquids, while remaining of a small diameter. SUMMARY OF THE INVENTION [0007] The present invention enables transporting distention medium efficiently through a single sheath surrounding a telescope used for endoscopy in bodily cavities. The invention also provides an automatic flow of medium, while maintaining distention of the cavity to be examined. This is achieved by having a higher hydraulic diameter for the inflow channel as opposed to the outflow channel. This implies that at any given time less fluid will be running out of than into the cavity. The retained fluid distends the cavity to be examined until resistance to distention is encountered, which then reduces the inflow and creates an equilibrium between flows. This automatic outflow set-up reduces the need for complicated pump systems and simplifies routine diagnostic procedures. [0008] A preferred embodiment of a single sheath continuous flow system for endoscopy according to the invention includes a single oval to round tubular structure which conforms to the outside of a telescope, with or without an instrument alongside it. The sheath has internal ridges which, when touching the outside of the telescope, create compartments of unequal hydraulic diameter between the endoscope and the sheath. The inflow area is larger than the outflow area. Under certain circumstances for a passive outflow, a slit is formed along the sheath at a distance from the tip which is introduced in the bodily cavity. This slit is located along the compartment which carries the outflow fluid. This allows a constant leakage of fluid, thus creating a continuous flow of medium through the system of endoscope and cavity. The continuous flow is an advantage as it allows blood and other bodily fluids which obscure the view to be eliminated. [0009] Among the advantages of the invention are that: reducing the number of sheaths from two to one potentially reduces their diameter; a single sheath system is easier to assemble; unequal compartments allow for automatic distention of bodily cavity; and the structure of the channels increases the hydraulic diameter and thus rheologic properties of the system. These and other advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments as shown in the several figures of the drawing. BRIEF DESCRIPTION OF THE DRAWING [0010] FIG. 1 is a cross-section of a conventional concentric-channel diagnostic probe; [0011] FIG. 2 is a cross-section showing example dimensions of an off-center-channel diagnostic probe according to the invention having ridges on the inside of a single sheath to create two unequal compartments when in contact with a telescope; [0012] FIGS. 3A, 3B and 3 C are cross-sections of a diagnostic endoscope sheath using one ridge to create two fluid channels according to the invention; [0013] FIGS. 4A, 4B and 4 C are cross-sections of an operative endoscope sheath according to the invention using two ridges to create three channels, the third for the introduction of an instrument; [0014] FIG. 5 is a side view of a Storz® endoscope of the type to be inserted through a sheath; [0015] FIG. 6 shows a side view of a sheath having a passive outflow slit in the sheath along the outflow channel; [0016] FIG. 7 shows a side view of a sheath having an active outflow which can be connected to suction; and [0017] FIG. 8 shows a side view of a sheath having an active outflow and an instrument channel. DETAILED DESCRIPTION OF THE INVENTION [0018] The present invention uses radial ridges along the inside of a sheath surrounding the telescope. Contact between the ridges and the telescope creates compartments or channels within the sheath, which carry the distention medium. FIG. 2 is a cross-section showing example dimensions of an off-center-channel diagnostic probe according to the invention. The ridges mounted on the inside of the single sheath create two unequal compartments when in contact with the telescope. These compartments are used as channels for in- and out-flow of distention medium. Comparing FIGS. 1 and 2 , it is evident that the invention's use of transverse ‘ribs’ increases the area available for inflow and outflow of distention medium. [0019] The replacement of conventional co-axial tubes system of irrigation by the present invention using a longitudinal ridge segmented system offers the following advantages: [0020] First, less volume of sheath wall material is used to separate channels, preserving more cross-sectional area for fluid flow. More area means less friction between the fluids and the channel wall surfaces. [0021] Second, the cross-sectional shape of the flow channel is changed to consolidate its area and shorten its perimeter, again resulting in less friction. Less contact between surface and liquid means less friction and therefore greater flow. [0022] The increase and consolidation of flow area combine to produce a significantly better flow characteristic for the segmented system. In calculating the so-called hydraulic diameter, the segmented system allows a diameter which is three times that of the co-axial system. This translates into a flow which is 3×3=9 times higher, as flow is relative to the square of the diameter. Hence, re-arranging the available space around the optic increases flow characteristics by a full order of magnitude. [0000] Using as an example the dimensions of the FIG. 1 conventional concentric-channel probe: [0000] Inflow (the Duct Nearest the Optic): [0000] Cross-sectional area=2.21 mmˆ2, wetted perimeter=19.63 mm Hydraulic diameter (Dh)=0.45 mm Outflow: Cross-sectional area=2.95 mmˆ2, wetted perimeter=26.23 mm Hydraulic diameter (Dh)=0.45 mm Using as an example the dimensions of the FIG. 2 off-center channel probe according to the invention: Inflow (the Larger of the Two Spaces): Cross-sectional area=4.96 mmˆ2, wetted perimeter=11.07 mm Hydraulic diameter (Dh)=1.79 mm Outflow: Cross-sectional area=2.86 mmˆ2, wetted perimeter=8.18 mm Hydraulic diameter (Dh)=1.39 mm [0031] As shown in FIG. 2 , the channels form a sharp angle with the optic, which in this design is reduced by creating an inner ridge on the sheath which hugs the optic. This angle is critical to flow. Narrow angles create turbulence in the flow of distention medium, depending on a number of issues relating to the medium which can not be anticipated when constructing a sheath for the scope. The bottom of the opening between the sheath's inner wall surface and the outer surface of the optic member could be a curve tangent to both surfaces. Based upon current commonly-used distention media, an optimum shape of the ridges on the inside of the sheath can be calculated to blunt these sharp angles. [0032] FIGS. 3A, 3B and 3 C are cross-sections of a diagnostic endoscope sheath according to the invention using one ridge to create two channels. The sharp edges with the endoscope are blunted to reduce troublesome turbulence. FIG. 3A shows the sheath without a telescope element installed. FIG. 3B shows the sheath with a telescope element installed. FIG. 3C is a cutaway perspective view of a sheath holding a telescope element. [0033] FIGS. 4A, 4B and 4 C are cross-sections of an operative endoscope sheath according to the invention, in an alternate embodiment using two ridges to create three channels. FIG. 4A shows the sheath empty. In addition to the two fluid channels, a third channel allows for the introduction of an instrument. FIG. 4B shows the sheath with a telescope element and an operative element both installed. FIG. 4C is a cutaway perspective view of a sheath holding a telescope element and an operative element. [0034] FIG. 5 is a side view of a Storz® endoscope of the type to be inserted through the diagnostic element channel of sheaths according to the invention. The segmented system having two components (sheath and telescope) rather than three makes the system of the invention friendly to assemble in an operating theatre. [0035] FIG. 6 is a side view of a sheath having a passive outflow slit in the sheath along the outflow channel at a distance from the tip of the endoscope. This allows a small volume of fluid to escape, thus creating a continuous flow. [0036] FIG. 7 is a side view of a sheath having an active outflow which can be connected to a source of suction to increase the amount of fluid flowing through the system. [0037] FIG. 8 is a side view of a sheath having an active outflow as well as an instrument channel. [0038] While the present invention is described in terms of several preferred embodiments, it will be appreciated by those skilled in the art that these embodiments may be modified without departing from the essence of the invention. It is therefore intended that the following claims be interpreted as covering any modifications falling within the true spirit and scope of the invention.	An endoscopy sheath has an inside surface with longitudinally extending, inwardly projecting ridges which will surround a telescope. Contact between the ridges and the telescope creates compartments or channels within the sheath, which carry a distention medium.	0
This application is a continuation of application Ser. No. 10/097,510, filed on Mar. 14, 2002 now abandoned. BACKGROUND OF THE INVENTION (1) Field of the Invention The present invention pertains to a lubricant retention assembly employed with an electric motor that has a self-contained lubricant reservoir. More specifically, the present invention pertains to a thrust collar mounted on the motor shaft and a bearing cap surrounding the thrust collar, where the thrust collar has an annular flange that throws lubricant leaking along the shaft radially outwardly toward the bearing cap and the bearing cap has an angled interior surface that deflects the lubricant thrown by the annular flange into the motor interior and toward the lubricant reservoir. In addition, a thrust washer is provided on the shaft adjacent the thrust collar for preventing lubricant leakage along the shaft between the interface of the shaft and thrust collar. The thrust washer and thrust collar have complementary configurations that maintain the thrust washer in position on the shaft adjacent the thrust collar. (2) Description of the Related Art In most motor constructions having rotating drive shafts, proper lubrication of the drive shaft and the bearing surfaces or bearing assemblies supporting the shaft is essential for insuring a prolonged operating life and quiet operation of the motor. Some larger motors are constructed with their own lubrication circuits where a pump pumps lubricant from a reservoir to the shaft bearing assemblies and the lubricant is then directed back to the reservoir. The internal combustion motors of automobiles are examples of these types of motors. Any lubricant lost from the motor over time due to leakage past the bearing assemblies supporting the motor shaft can be replenished by supplying additional lubricant to the motor reservoir from a separate source. Because the lubricant can be replenished with periodic maintenance of the motor, the occasional loss of lubricant or loss of lubricant over time does not significantly detract from the operating life of the motor. However, this is not the case with smaller motors, for example electric motors used in electric household appliances like dishwashers, clothes washers and clothes dryers. These types of motors are contained in the enclosures of the appliance and are inaccessible for replenishing lubricant lost due to leakage. The lubrication reservoir of these types of motors is self-contained and cannot be replenished. The motor shafts for small motor constructions are usually not supported for rotation by ball bearing or roller bearing assemblies, but by sleeve bearings or porous sintered metal bearings where bearing surfaces support the shafts for rotation. Loss of lubricant from these types of motors can cause the bearings to fail and can have serious consequences on the motor's operational life. One of the major causes for sleeve bearing failures is loss of oil out of the bearing/lubrication system. An example of a conventional bearing/lubrication system used in appliance motor designs is shown in FIG. 1 . The system shown in FIG. 1 is known in the prior art, and therefore only a partial view of the motor is shown. FIG. 1 shows a porous powdered metal or babbitt metal type bearing ( 10 ) supporting the motor shaft ( 12 ) for rotation in an end shield ( 14 ) of the motor. The center axis A—A of the shaft ( 12 ) defines mutually perpendicular axial and radial directions. A cooling fan ( 16 ) is shown mounted on the shaft ( 12 ) to the right of the bearing assembly shown in FIG. 1 . The interior of the motor is to the right of the end shield in FIG. 1 . The shaft ( 12 ) extends through a cylindrical collar ( 18 ) of the motor end shield that surrounds the end shield shaft opening ( 20 ). The bearing ( 10 ) is held in the shaft opening ( 20 ) by its engagement with bearing seat surfaces ( 22 ) of the end shield on one side of the bearing and a bearing retainer ( 24 ) on the opposite side of the bearing. The typical bearing retainer ( 24 ) is constructed as a stamped metal disc ( 26 ) with a peripheral rim ( 28 ) that is press-fit into the end shield collar ( 18 ). A plurality of resilient fingers ( 30 ) project radially inwardly from the disk ( 26 ) and engage against the bearing ( 10 ) and hold the bearing to the bearing seat surfaces ( 22 ). The typical bearing lubricant feeding and return system comprises a lubricating oil, felt or other fibrous material ( 32 ) injected with the oil, a thrust collar/oil slinger ( 34 ) and a bearing cap ( 36 ). As seen in FIG. 1 , the thrust collar/oil slinger ( 34 ) is mounted in a press-fit engagement on the shaft ( 12 ). A rubber washer ( 38 ) and a metal washer ( 40 ) are positioned between the collar ( 34 ) and the bearing ( 10 ). The engagement of the rubber washer ( 38 ) around the shaft provides a seal around the shaft surface that minimizes oil from leaking out of the motor interior along the interface between the shaft and the interior bore of the thrust collar ( 34 ). The metal washer ( 40 ) provides a sliding surface between the rubber washer ( 38 ) and the bearing ( 10 ) that prevents wear of the rubber washer on rotation of the shaft. The bearing cap ( 36 ) is typically stamped from sheet metal and is formed with a resilient annular outer wall ( 42 ) that is press-fit into the end shield collar ( 18 ) surrounding the shaft opening ( 20 ). A cylindrical side wall ( 44 ) extends axially from the bearing cap outer wall ( 42 ) to a circular end wall ( 46 ) of the bearing cap. The bearing cap end wall ( 46 ) extends radially inwardly from the bearing cap side wall ( 44 ) toward the motor shaft ( 12 ) and terminates at an axially inwardly projecting lip ( 48 ) of the cap. The cap lip ( 48 ) is spaced radially outwardly from the fan ( 16 ) and shaft ( 12 ) leaving a clearance area ( 50 ) between the cap lip ( 48 ) and the fan ( 16 ) and shaft ( 12 ). The area axially between the bearing retainer disk ( 26 ) and the bearing cap end wall ( 46 ) and radially outside the dashed line B—B shown in FIG. 1 is typically occupied by the lubricant-permeated fibrous material. This material is not shown in FIG. 1 to avoid obscuring other component parts of the bearing lubrication system. In the intended operation of the prior art bearing lubrication system shown in FIG. 1 , any lubricant advancing along the shaft ( 12 ) would be restricted from passing through the interface of the thrust collar/oil slinger ( 34 ) and the shaft by the rubber washer ( 38 ). The washer ( 38 ) is typically stretched as it is mounted on the shaft ( 12 ) and is in a tight engagement around the shaft, preventing any lubricant from advancing beyond the washer out of the motor. However, rotation of the shaft ( 12 ) also causes lubricant that is advanced along the shaft to move radially outwardly over the metal washer ( 40 ) and the thrust collar/oil slinger ( 34 ). Any lubricant that travels radially outwardly over the surfaces of the metal washer ( 40 ) is thrown from the peripheral edge of the metal washer into the fibrous material ( 32 ) that absorbs the lubricant. The material ( 32 ) wicks the lubricant back to the bearing ( 10 ). The lubricant soaks through the porous bearing to its center bore, re-lubricating the rotating engagement of the shaft ( 12 ) with the bearing ( 10 ). Any lubricant that travels radially outwardly along the rubber washer ( 38 ) is transferred to either the metal washer ( 40 ) or the thrust collar/oil slinger ( 34 ) which have greater radial dimensions than the rubber washer. Any lubricant that travels radially outwardly along the thrust collar/oil slinger ( 34 ) is thrown radially off of an annular rim ( 54 ) on the side of the thrust collar or off of the outer peripheral edge ( 56 ) of the thrust collar to the fibrous material ( 32 ). This lubricant is then wicked through the material ( 32 ) back to the porous bearing ( 10 ) that absorbs the lubricant and again transfers the lubricant to the rotating engagement of the shaft ( 12 ) with the bearing ( 10 ). The bearing lubrication system described above and shown in FIG. 1 has been found to be disadvantaged in that lubricant thrown radially off the spinning thrust collar will at times impact against the interior surface of the fibrous material ( 32 ) represented by the dashed lines B—B and splash back onto the surface of the thrust collar ( 58 ) outside of or to the right of the thrust collar peripheral edge ( 56 ). When the motor is stopped or running, oil that has splashed onto the thrust collar outer surface ( 58 ) can advance along the surface of the fan hub ( 60 ) reaching the fan blades ( 62 ). The next time the motor is activated, the lubricant that reaches the fan hub ( 60 ) and fan blades ( 62 ) will fly off the blades, resulting in a loss of lubricant from the lubricant reservoir of the motor. In addition, when motors having a bearing lubrication system such as that shown in FIG. 1 are employed in a clothes dryer, lint can collect in the opening or clearance ( 50 ) between the bearing cap lip ( 48 ) and the fan ( 16 ) and soak up oil, causing additional loss of lubricant from the motor lubricant reservoir. Over time, the loss of oil can result in failing of the motor bearings requiring repair of the motor and the appliance. What is needed to overcome the above shortcomings of the prior art bearing lubrication system is a system that reliably retains lubricant in the self-contained lubricant reservoir of an electric motor. SUMMARY OF THE INVENTION The lubricant retention assembly of the invention overcomes the shortcomings of the prior art bearing lubrication system by providing a thrust collar and a bearing cap that are designed to function together to reliably return any lubricant that reaches the thrust collar to the oil-permeated fibrous material of the self-contained lubricant reservoir of the motor. In addition to the novel constructions of the thrust collar and bearing cap, the bearing lubrication system of the invention also comprises a rubber washer of novel construction that is complementary to the construction of the thrust collar and a novel application of the fibrous material impregnated with the lubricant that forms the lubricant reservoir of the invention. The thrust collar and thrust washer of the invention are mounted on the motor shaft in basically the same positions as the thrust collar and thrust washer of the prior art, and the bearing cap of the invention is mounted in the end shield collar surrounding the shaft opening of the end shield in basically the same position as the bearing cap of the prior art. The thrust collar has a cylindrical hub that is mounted on the shaft. The collar hub has a center bore surrounded by a cylindrical interior surface of the hub. The hub interior surface is dimensioned so that the thrust collar will fit in a friction engagement on the exterior surface of the shaft for rotation of the collar with the shaft. The thrust collar hub also has a cylindrical exterior surface that extends between axially opposite first and second annular end surfaces of the thrust collar. The first annular end surface of the collar hub faces toward the bearing of the motor shaft. This first end surface of the collar hub is beveled so that it extends axially over the shaft as it extends from the interior surface of the collar hub to the exterior surface of the collar hub. The opposite, second annular end surface of the hub has an annular flange that extends radially outwardly from the hub. As the annular flange extends radially away from the collar hub, it also extends axially over the hub exterior surface, giving the flange a conical shape. The flange extends radially outwardly to a peripheral end surface of the flange that is parallel to the center axis of the motor shaft and extends around the hub exterior surface. The bearing cap is mounted to the end shield collar surrounding the shaft opening of the end shield. The bearing cap has an annular side wall that extends axially away from the end shield collar and the bearing and radially toward the thrust collar mounted on the shaft. The cap side wall extends radially inwardly to an inner edge of the cap that extends around the annular flange of the thrust collar on an axially opposite side of the flange peripheral end surface from the bearing. In the bearing lubrication system of the invention, the fibrous material permeated with the lubricant is packed in the end shield collar against the bearing retainer and surrounding the bearing. However, the fibrous material does not extend axially beyond the end of the bearing and does not enter into the area surrounded by the bearing cap as was done in the prior art. The conventional rubber washer of the prior art is replaced in the bearing lubrication system of the invention with a resilient o-ring. The o-ring is slightly stretched as it is positioned on the shaft in the same position as the prior art rubber washer, between the metal washer and the first annular end surface of the thrust collar. The circular cross section of the o-ring thrust washer provides an improved lubricant seal that prevents lubricant from passing along the shaft exterior surface and between the interface of the shaft and the interior surface of the o-ring thrust washer. In addition, with the reduced exterior diameter dimension of the thrust collar hub, a conventional rubber washer would be prone to stretching away from the shaft and moving onto the thrust collar hub due to any relative rotation between the thrust collar and metal washer and/or due to a high thrust impact or a high thrust load on the shaft. With the rubber washer moved onto the thrust collar hub, it is ineffective in stopping lubricant leakage along the shaft and also creates axial end play of the shaft. The circular cross section of the o-ring thrust washer seats inside a conical or frustum shaped recess formed by the beveled first annular end surface of the thrust collar hub. Because the first annular end surface of the thrust collar hub extends over a portion of the o-ring as the end surface extends from the interior bore surface of the hub to the exterior surface of the hub, the annular end surface prevents the o-ring from expanding or stretching outwardly from the shaft surface due to any relative rotation between the thrust collar and the bearing and/or due to a high thrust impact or a high thrust load on the shaft, and thereby prevents the o-ring thrust washer from leaving the shaft surface and moving onto the hub of the thrust collar. Thus, with the thrust collar of the invention mounted on the motor shaft and the bearing cap of the invention surrounding the thrust collar, any lubricant that leaks along the shaft to the thrust collar will be thrown from the thrust collar flange toward the angled interior surface of the cap side wall and will be deflected by the cap side wall back into the motor interior toward the fibrous material of the lubricant reservoir. In addition, with the o-ring thrust washer of the invention mounted on the shaft preventing lubricant leakage between the interface of the shaft and the thrust collar, the beveled annular end surface of the thrust collar hub will prevent the o-ring thrust washer from moving from its position on the shaft onto the hub of the thrust collar. BRIEF DESCRIPTION OF THE DRAWINGS Further features of the invention are revealed in the following detailed description of the preferred embodiment of the invention and in the drawing figures wherein: FIG. 1 is a partial sectioned view of a motor end shield and shaft of the prior art bearing lubrication system; and FIG. 2 is a partial sectioned view of the same motor end shield and shaft of FIG. 1 and also showing the bearing lubrication system of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As stated earlier, the lubricant retention assembly of the invention overcomes the shortcomings of the prior art bearing lubrication system by providing a thrust collar ( 70 ) and a bearing cap ( 72 ) that are designed to function together to reliably return any lubricant that reaches the thrust collar to the oil permeated fibrous material of the self contained lubricant reservoir of the motor. In addition to the novel constructions of the thrust collar ( 70 ) and bearing cap ( 72 ), the bearing lubrication system of the invention also comprises a rubber washer ( 76 ) of novel construction that is complementary to the construction of the thrust collar as well as a novel application of the lubricant permeated fibrous material that forms the lubricant reservoir of the invention. Because the lubricant retention assembly of the invention is an improvement over the prior art bearing lubrication system described earlier, the assembly of the invention will be described and explained using the same operative environment of FIG. 1 that was employed in describing the prior art bearing lubrication system. The component parts of the motor referred to in describing the prior art bearing lubrication system shown in FIG. 1 make up the illustrated environment of the lubrication retention assembly of the invention shown in FIG. 2 and are identified by the same reference numbers shown in FIG. 1 . The thrust collar ( 70 ) of the invention is preferably constructed of a plastic material, but may be constructed of other types of materials. The thrust collar ( 70 ) is basically comprised of a cylindrical hub ( 80 ) and an annular flange ( 82 ) projecting radially outwardly from one end of the hub. The collar hub ( 80 ) has a cylindrical exterior surface ( 84 ) and a cylindrical interior surface ( 86 ). The hub interior surface ( 86 ) surrounds a center bore ( 88 ) of the hub and has an interior diameter dimension that allows the hub to be slipped on the shaft ( 12 ) in an interference fit or friction fit between the hub ( 80 ) and shaft ( 12 ) that causes the thrust collar ( 70 ) to rotate with the shaft ( 12 ). The thrust collar hub ( 80 ) has an axial length between opposite first ( 88 ) and second ( 90 ) annular end surfaces of the thrust collar. The first annular end surface ( 88 ) faces toward the bearing ( 10 ) and the motor end shield ( 14 ) and the opposite second annular end surface ( 90 ) faces away from the bearing and end shield. The first annular end surface ( 88 ) of the hub is beveled so that it extends radially away from the shaft ( 12 ) and axially over the shaft ( 12 ) as it extends from the thrust collar hub interior surface ( 86 ) to the thrust collar hub exterior surface ( 84 ). The beveled configuration of the first annular end surface ( 88 ) defines a conical or frustum shaped recessed area ( 92 ) within the first annular end surface ( 88 ). The opposite, second annular end surface ( 90 ) of the hub is a flat surface that is perpendicular to the shaft center axis and extends radially outwardly and merges with the thrust collar annular flange ( 82 ). As the annular flange ( 82 ) extends radially outwardly from the thrust collar hub exterior surface ( 84 ) it gradually angles over the hub exterior surface ( 84 ), giving the flange ( 82 ) a conical shape. The flange has opposite interior ( 94 ) and exterior ( 96 ) surfaces that both extend axially over the thrust collar hub exterior surface ( 84 ) as they extend radially away from the thrust collar hub ( 80 ). The flange interior ( 94 ) and exterior ( 96 ) surfaces extend radially away from the thrust collar hub ( 80 ) to a peripheral end surface ( 98 ) of the flange. The flange peripheral end surface ( 98 ) is parallel to the center axis of the motor shaft and extends around the hub exterior surface ( 84 ). The flat peripheral end surface ( 98 ) of the flange merges with the angled interior surface ( 94 ) of the flange and forms a sharp annular corner or edge ( 100 ) on the flange that promotes oil droplet formation. The bearing cap ( 72 ) is stamped from metal as is the bearing cap ( 36 ) of the prior art. Other types of materials could also be used in constructing the bearing cap. The bearing cap ( 72 ) of the invention is formed with a rim ( 102 ) at its outer perimeter that is dimensioned to be press fit into the end shield collar ( 18 ) in attaching the bearing cap ( 72 ) over the shaft opening ( 20 ) of the end shield collar ( 18 ). An annular bend ( 104 ) formed in the bearing cap connects the outer rim ( 102 ) of the cap with an annular side wall ( 106 ) of the bearing cap. The bearing cap side wall ( 106 ) has opposite exterior ( 108 ) and interior ( 110 ) surfaces that both extend radially inwardly as the side wall extends from the cap outer rim ( 102 ) toward the shaft ( 12 ). As seen in FIG. 2 , the bearing cap side wall ( 106 ) extends axially away from the end shield collar ( 18 ) and axially away from the bearing ( 10 ) as it extends radially inwardly toward the thrust collar ( 34 ) mounted on the motor shaft ( 12 ). This gives the side wall ( 106 ) a conical shape. The bearing cap side wall ( 106 ) extends radially inwardly to an inner annular bend ( 112 ) formed in the cap that curves inside the side wall interior surface ( 110 ) to an inner annular edge ( 114 ) of the cap. The inner edge ( 114 ) of the cap side wall extends completely around the thrust collar flange ( 82 ) on an axially opposite side of the flange peripheral end surface ( 98 ) from the shaft bearing ( 10 ). As seen in FIG. 2 , the side wall inner edge ( 114 ) is dimensioned to provide only a minimum amount of clearance for passage of the thrust collar annular flange ( 82 ) through the opening defined by the bearing cap sidewall inner edge ( 114 ). In the bearing lubrication system of the invention, the fibrous material permeated with the lubricant ( 116 ) is packed in the end shield collar ( 18 ) against the bearing retainer ( 24 ) and surrounding the bearing ( 10 ), but does not extend into the area surrounded by the bearing cap side wall ( 106 ) as was done in the prior art bearing lubrication system. Instead, the lubricant permeated fibrous material ( 116 ) is packed into the end shield collar ( 18 ) surrounding the bearing ( 10 ) and does not extend axially beyond the bearing or beyond the dashed line C—C shown in FIG. 2 in the preferred embodiment of the invention. In the bearing lubrication system of the invention, the conventional rubber washer of the prior art is replaced with a resilient washer having at least a portion dimensioned to fit into the recess at the thrust collar first end surface, preferably an o-ring ( 76 ). The o-ring thrust washer ( 76 ) has an interior diameter dimension that is slightly smaller than the exterior diameter dimension of the shaft ( 12 ), resulting in the o-ring being stretched slightly as it is positioned on the shaft in the same position as the prior art rubber washer, i.e. between the metal washer ( 40 ) and the first annular end surface ( 88 ) of the thrust collar. The o-ring ( 76 ) also has an exterior diameter dimension that is slightly smaller than the exterior diameter dimension of the thrust collar hub exterior surface ( 84 ). The circular cross section of the o-ring thrust washer ( 76 ) provides an improved lubricant seal that prevents lubricant from passing along the exterior surface of the shaft ( 12 ) and between the interface of the shaft ( 12 ) and the interior of the o-ring thrust washer ( 76 ). The dimensioning of the o-ring thrust washer ( 76 ) also allows it to be received at least partially in the frustum shaped recessed area ( 92 ) surrounded by the first annular surface ( 88 ) of the thrust collar. As explained earlier, the reduced exterior diameter dimension of the thrust collar hub ( 80 ) could lead to the conventional rubber washer stretching away from the shaft ( 12 ) and moving onto the thrust collar hub due to any relative rotation between the thrust collar and the metal washer and/or due to a high thrust impact or a high thrust load on the shaft. With the rubber washer moved onto the thrust collar hub, it would be ineffective in stopping lubricant leakage along the shaft. The circular cross section of the o-ring thrust washer ( 76 ) and its dimensioning seat the o-ring inside the conical or frustum shaped recess ( 92 ) formed by the beveled first annular end surface ( 88 ) of the thrust collar hub. A portion of the hub first annular end surface ( 88 ) extends axially over the o-ring thrust washer ( 76 ) and thereby prevents the thrust washer from stretching away from the shaft ( 12 ) and moving onto the thrust collar hub ( 80 ). In operation of the lubricant retention assembly of the invention, as the shaft ( 12 ) rotates, the tight, stretched engagement of the o-ring thrust washer ( 76 ) around the shaft prevents any leakage of lubricant along the shaft beyond the o-ring ( 76 ) where it could potentially pass through the interface between the thrust collar ( 70 ) and the shaft and reach the fan ( 16 ) where the lubricant would be thrown from the motor. Any lubricant that reaches the exterior surface ( 84 ) of the thrust collar hub and moves away from the motor interior to the thrust collar annular flange ( 82 ) will be cause to move across the flange interior surface ( 86 ) by rotation of the thrust collar. The lubricant moving over the flange interior surface ( 86 ) will reach the flange peripheral edge corner ( 100 ). The sharp annular corner ( 100 ) between the flange interior surface ( 86 ) and the flange peripheral end surface ( 98 ) causes lubricant droplets to be thrown radially off of the edge corner ( 100 ) toward the interior surface ( 110 ) of the bearing cap annular side wall ( 106 ). The lubricant droplets thrown from the thrust collar ( 80 ) impact against the bearing cap side wall interior surface ( 110 ) and are deflected axially inwardly toward the fibrous material ( 116 ) packed around the bearing ( 10 ). Thus, the problem of splashing lubricant impacting with the fibrous material being deflected outside the bearing cap of the prior art is eliminated. The close tolerance between the bearing cap side wall inner edge ( 114 ) and the thrust collar flange peripheral surface ( 98 ) ensures that no lubricant is deflected from the bearing cap ( 72 ) outside the bearing cap and the thrust collar flange ( 82 ) where it would be lost from the lubricant reservoir. While the present invention has been described by reference to a specific embodiment, it should be understood that modifications and variations of the invention may be constructed without departing from the scope of the invention defined in the following claims.	A lubricant retention assembly is employed with an electric motor to prevent the loss of lubricant from a self contained lubricant reservoir of the motor. The lubricant retention assembly includes a thrust collar mounted on the motor shaft and a bearing cap surrounding the thrust collar, where the thrust collar has an annular flange that throws lubricant leaking along the shaft radially outwardly toward the bearing cap. The bearing cap has an angled interior surface that deflects the lubricant thrown from the annular flange of the thrust collar back into the motor interior and toward the lubricant reservoir. A thrust washer is also provided on the shaft adjacent the thrust collar and prevents lubricant leakage along the shaft between the interface of the shaft and the thrust collar. The thrust washer and thrust collar have complementary configurations that maintain the thrust washer in position on the shaft adjacent the thrust collar.	5
CROSS-REFERENCE TO RELATED APPLICATION(S) This application is a continuation-in-part of, and claims the benefit of, U.S. patent application Ser. No. 13/447,733, filed Apr. 16, 2012, which is a continuation of U.S. patent application Ser. No. 12/622,832, filed Nov. 20, 2009, which issued on Apr. 17, 2012 as U.S. Pat. No. 8,157,991 the entirety of each of which is hereby incorporated herein by reference. This application also claims the benefit of U.S. Provisional Patent Application Ser. No. 61/674,327, filed on Apr. 16, 2012, the entirety of which is hereby incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to utility systems and, more specifically, to a prefabricated segmented system for building bio-retention system enclosures. 2. Description of the Prior Art Storm water runoff places a substantial economic burden on public water treatment facilities. As open land comes under development and is paved over, storm water that would otherwise be absorbed by soil flows into local storm sewer systems. Such water often suspends solids and other pollutants as it flows over paved surfaces. Once in the storm sewer system, the water flows to a water treatment facility where it must be treated to remove the solids and pollutants. Not only is such water treatment expensive, but so is the cost of infrastructure improvements necessary to convey the storm water. Local bio-retention basins are increasingly used to catch storm water and allow it to settle solids locally before transfer to a storm sewer system. Many such basins also allow storm water to be infiltrated into the surrounding soil, thereby reducing the demands placed on the local storm sewer system. A bio-retention system can be configured as a rain garden. A rain garden is a garden that diverts storm water for storm water filtration and groundwater recharge. Typically, a rain garden includes an area that retains storm water that would otherwise flow into the storm sewer system. Rain gardens mitigate the effects of runoff in urban areas by allowing storm water to seep into the water table, thereby filtering the water by the surface soil and preventing flow of the storm water into the storm sewer system. Also, some rain gardens use storm water to grow aesthetically pleasing plants, thereby making urban areas more attractive. Use of rain gardens in medians and next to sidewalks that would otherwise be paved over results in less stress on the municipality's drainage systems, improved groundwater quality and a more pleasing urban environment. Most bio-retention basins include a surrounding curb or retaining wall used to form an enclosure that keeps water local to the basin. Water inlets are included to allow water to flow into the basin and water outlets are provided to allow overflow to exit the basin. Unfortunately, in an urban environment, construction of bio-retention basins can be difficult to construct and expensive. One method of constructing such a basin includes setting concrete forms in the configuration of the basin, placing concrete in the forms, allowing the concrete to cure, removing the forms and then placing gravel and soil in the basin. This method is costly, labor intensive and may be difficult to perform in a limited urban environment. Another method includes pre-casting an entire unitary retention system designed to fit into a specific site. The unitary system is then transported to the site on a truck and then installed. Such a unitary system can be bulky and costly to transport. This method may also be difficult to use in limited urban environments and it is inflexible because once installed, it cannot be easily modified. Therefore, there is a need for a segmental bio-retention enclosure system that is prefabricated, easily transported, inexpensive and that can be arranged in various layouts to accommodate given site conditions. SUMMARY OF THE INVENTION The disadvantages of the prior art are overcome by the present invention which, in one aspect, is a bio-retention basin enclosure system that includes a plurality of prefabricated vertical wall segments and a baffle unit. Each of the plurality of wall segments includes a horizontal top end that defines a notch, an opposite horizontal and substantially flat bottom end, a first vertical edge, a second opposite vertical edge, a front vertical surface and an opposite back vertical surface. Each of the first vertical edge and the second vertical edge defines at least one cylindrical bore configured to receive a connecting dowel therein. The baffle unit is configured to be coupled to at least one of the plurality of prefabricated vertical wall segments and to be held in alignment therewith by at least one connecting dowel. The baffle unit includes a water velocity reduction member that is configured to reduce a velocity of water flowing into the baffle unit. At least one connecting dowel has dimensions complimentary to the bore defined by the plurality of prefabricated vertical wall segments and the bore defined by the baffle unit so as to be configured to hold the baffle unit in alignment with at least one of the plurality of prefabricated vertical wall segments. In another aspect, the invention is a system for constructing bio-retention basin enclosures system that includes a plurality of prefabricated vertical wall segments, at least one prefabricated baffle segment, a planar grate segment, and at least two prefabricated baffle vertical wall members. Each of the plurality of wall segments includes a horizontal top end that defines a notch, an opposite horizontal bottom end, a first vertical edge, a second opposite vertical edge, a front vertical surface and an opposite second vertical surface. Each of the first vertical edge and the second vertical edge defines at least one cylindrical bore configured to receive a connecting dowel therein. The at least one prefabricated baffle segment includes a vertical edge surface, defining a plurality of cylindrical bores, each of which is configured to receive a connecting dowel therein, and a planar member from which a plurality of protrusions extend upwardly therefrom so that the baffle segment is configured to reduce water flow velocity. The planar grate segment defines a plurality of holes passing there through. The at least two prefabricated baffle vertical wall members each have a planar vertical surface that defines a plurality of cylindrical bores disposed so that at least one of the cylindrical bores defined by the vertical edge surface of the prefabricated concrete baffle segment is configured to be placed in alignment therewith. The two baffle vertical wall members are configured to support the prefabricated concrete baffle segment and the planar grate segment so as to form a baffle unit. In another aspect, the invention is a retention basin enclosure that includes a plurality of prefabricated concrete vertical wall segments, a baffle unit and at least one steel connecting dowel. Each of the plurality of wall segments includes a horizontal top end that defines a notch, an opposite horizontal bottom end, a first vertical edge, a second opposite vertical edge, a front vertical surface and an opposite second vertical surface, each of the first vertical edge and the second vertical edge defining at least one cylindrical bore. The at least one prefabricated concrete baffle segment includes a vertical edge surface that defines a plurality of cylindrical bores and a horizontal planar member from which a plurality of protrusions extend upwardly therefrom so that the baffle segment is configured to reduce water flow velocity. A planar grate segment defines a plurality of holes passing there through. At least two prefabricated concrete baffle vertical wall members each have a planar vertical surface that defines a plurality of cylindrical bores disposed so that at least one of the cylindrical bores defined by the vertical edge surface of the prefabricated concrete baffle segment is configured to be placed in alignment with at least one of the cylindrical bores defined by the planar vertical surface. At least one steel connecting dowel has a first portion of which that is disposed in the bore defined by a selected one of the plurality of prefabricated concrete vertical wall segments and a second portion of which that is disposed in the bore defined by one of the vertical edge surface of the baffle unit so as to couple the at least one of the plurality of prefabricated vertical wall segments to the baffle unit. In another aspect, the invention is a retention basin for making an enclosure in soil that includes a plurality of interlocking concrete vertical wall segments. Each segment is engaged with an adjacent segment so as to form an enclosed basin. Each segment has a vertical wall and a top edge that defines a lifting bore that is complimentary in shape to a removable lifting bolt that is configured to provide a lifting attachment point for a lifting cable. Each segment includes an internal bore configured to be in linear alignment with the internal bore of the adjacent segment. A metal pin is disposed in the internal bores of two adjacent segments and is configured to maintain the two adjacent segments in alignment. An elongated eyebolt includes an eye portion disposed around the metal pin. A plate is bolted to the elongated eyebolt and driven against the vertical walls of two adjacent segments and is secured to the eyebolt with a nut. The nut is torqued so as to apply a predetermined tension to the eyebolt and a predetermined force to the plate so that the plate and the metal pin maintain the two segments in a substantially fixed spatial relationship. An earth anchor has a first end attached to the eyebolt and a second end, spaced apart from the first end, that includes an anchoring shape that is buried in the soil so as to provide lateral support to the two segments bolted to the plate. A post-installation attachment is affixed to the lifting bore of at least one segment. In another aspect, the invention is a retention basin segment pair that includes a first concrete wall segment having a first side edge. The first side edge includes a first vertical edge portion having a bottom, a step edge portion extending laterally from the bottom of the first vertical edge portion and having a distal end, and a second vertical edge portion extending downwardly from the distal end of the step edge portion. The step edge portion defines a first internal bore. A second concrete wall segment has a second side edge that is complimentary in shape to the first side edge of the first concrete wall segment. The second side edge includes a first vertical edge portion having a bottom, a step edge portion extending laterally from the bottom of the first vertical edge portion and having a distal end, and a second vertical edge portion extending downwardly from the distal end of the step edge portion. The step edge portion defines a second internal bore. The second concrete wall segment is disposed next to the first concrete wall segment so that the first internal bore is in alignment with the second internal bore. A metal pin is disposed in both the first internal bore and the second internal bore. An elongated bolt is secured to the metal pin. A plate is bolted to the elongated bolt and is driven against both the first concrete segment and the second concrete segment and is secured to the eyebolt with a nut. The nut is torqued so as to apply a predetermined tension to the eyebolt and a predetermined force to the plate so that the plate and the metal pin maintain the first concrete segment in a substantially fixed spatial relationship with the second concrete segment. An earth anchor has a first end attached to the eyebolt and a second end, spaced apart from the first end, that includes an anchoring shape that is configured to be buried in soil so as to provide lateral support to the first concrete segment and to the second concrete segment. In yet another aspect, the invention is a method of constructing a retention basin, in which a first concrete wall segment is placed into an excavation. The first concrete wall segment has a first side edge, the first side edge including a first vertical edge portion having a bottom, a step edge portion extending laterally from the bottom of the first vertical edge portion and having a distal end, and a second vertical edge portion extending downwardly from the distal end of the step edge portion, the step edge portion defining a first internal bore. A second concrete wall segment is placed into the excavation. The second concrete wall segment has a second side edge that is complimentary in shape to the first side edge of the first concrete wall segment. The second side edge includes a first vertical edge portion having a bottom, a step edge portion extending laterally from the bottom of the first vertical edge portion and having a distal end, and a second vertical edge portion extending downwardly from the distal end of the step edge portion. The step edge portion defines a second internal bore. The second concrete wall segment is disposed next to the first concrete wall segment so that the first internal bore is in alignment with the second internal bore. A metal pin is placed in both the first internal bore and the second internal bore so as to hold the first concrete wall segment in alignment with the second concrete wall segment. An elongated bolt is secured to the metal pin. A plate is passed around a portion of the elongated bolt and the plate is driven against both the first concrete segment and the second concrete segment. The plate is then secured to the eyebolt with a nut. The nut is torqued sufficiently so as to apply a predetermined tension to the eyebolt and a predetermined force to the plate so that the plate and the metal pin maintain the first concrete segment in a substantially fixed spatial relationship with the second concrete segment. An earth anchor is driven into soil to provide lateral support to the first concrete segment and to the second concrete segment. The earth anchor has a first end attached to the eyebolt and a second end, spaced apart from the first end. The second end includes an anchoring shape that is driven into the soil. These and other aspects of the invention will become apparent from the following description of the preferred embodiments taken in conjunction with the following drawings. As would be obvious to one skilled in the art, many variations and modifications of the invention may be effected without departing from the spirit and scope of the novel concepts of the disclosure. BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS FIGS. 1-5 are schematic diagrams of different modular components of a retention basin system. FIGS. 6A-6C are top plan views showing the coupling of a first segment and a second segment. FIGS. 7A and 7B are schematic diagrams of an inflow baffle unit constructed from components shown in FIGS. 3-5 . FIG. 8 is an elevational view of one configuration for a retention basin wall using modular components shown in FIGS. 1 and 5 . FIGS. 9A-9C are top plan views of different configurations of retention basins that can be constructed using the modular components shown in FIGS. 1-5 . FIG. 10 is a drawing of one embodiment employed in a rain garden. FIGS. 11A-11B are schematic drawings of a T-shaped segment. FIGS. 12A-12B are schematic drawings of an S-shaped segment. FIGS. 13A-13B are schematic drawings of an inverted T-shaped segment. FIGS. 14A-14B are schematic drawings of a wall constructed with T-shaped and S-shaped segments. FIGS. 15A-15B are schematic drawings of a curved S-shaped segment. FIGS. 16A-16B are schematic drawings of a curved inverted T-shaped segment. FIG. 17 is a schematic drawing of a semicircular basin. FIG. 18A is a schematic drawing of two basin segments and an anchoring device. FIG. 18B is a schematic cross sectional drawing of the drawing shown in FIG. 18A , taken along line 18 B- 18 B. FIG. 18C is a schematic cross sectional drawing of a portion of the drawing shown in FIG. 18 Bm taken along line 18 C- 18 C. FIG. 18D is a schematic diagram of an anchoring shape. FIG. 19A is a schematic drawing of two basin segments during installation. FIG. 19B is a schematic drawing of the two basin segments shown in FIG. 19A after installation. DETAILED DESCRIPTION OF THE INVENTION A preferred embodiment of the invention is now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. Unless otherwise specifically indicated in the disclosure that follows, the drawings are not necessarily drawn to scale. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” As shown in FIGS. 1-5 , one embodiment employs a kit of modular segments that are typically constructed from precast concrete. The segments may be put together to form the structure of an enclosure for a retention basin (which, in one representative embodiment can include a rain garden). For example, FIG. 1 shows a main wall segment 100 having a top end 102 a bottom end 104 , two side ends 106 , a front vertical surface 114 and an opposite back vertical surface 115 . Typically, the top end 102 has a rectangular notch 110 formed therein for allowing storm water to drain into or out of the retention basin. The notch 110 includes a substantially flat bottom surface 116 and two vertical surfaces 118 . When the bottom surface 116 is placed at ground level, the notch 110 provides a drain for water flowing into or out of the basin. The ends 106 of the segments 100 include a mechanism to maintain the segments in alignment. For example, bores 112 (which could be cylindrical or, as those of skill in the construction art would readily recognize, of another shape such as prismatic) are be formed therein to receive connecting dowels. When aesthetics require a top surface without a notch 110 , the segment may be inverted so that the bottom end 104 is on top and the notch 110 is buried. A shortened segment 200 is shown in FIG. 2 . This segment 200 may be used to allow different geometric configurations that would not be possible using only the main segment 100 . As will be readily appreciated by those of skill in the construction arts, the specific dimensions of the segments and the materials from which they are constructed can vary depending on the specific application. A drain grate segment 300 is shown in FIG. 3 . This segment 300 is used to allow storm water to drain into the retention basin while allowing people to walk on the grate. The drain grate segment 300 includes a plurality of holes 310 passing therethrough. Typically, this segment 300 is used with a water baffle segment 400 and a vertical wall segment 500 to form a baffle unit. The water baffle segment 400 includes an edge surface 402 that defines several bores 112 and a horizontal surface 410 from which plurality of protrusions 420 extend upwardly therefrom (and possibly indentations). The baffle segment 400 is used to reduce the velocity of incoming water and to disperse the water over a wider area so as to reduce local erosion in the retention basin. As shown in FIGS. 6A-6C , the segments 100 (and similar segments disclosed above) include bores 112 that allow them to be held in alignment with each other when a dowel 120 (such as a steel rod, a stainless steel rod, or a rod made of another material having a suitable shear strength for the specific application) is placed therein. A corner configuration is shown in FIGS. 6A-6B , wherein FIG. 6A shows the segments 100 prior to coupling and FIG. 6B shows the segments 100 after coupling. An end-to-end configuration is shown in FIG. 6C . An example of a baffle unit 600 constructed from the segments discussed above is shown in FIG. 7A . Such a structure includes two vertical wall segments 500 that are coupled to a baffle segment 400 with four dowels 120 . A drain grate segment 300 coupled to the vertical wall segments 500 with several metal corner brackets 610 (or other types of fasteners as would be readily appreciated by those of skill in the art). As water drains in through the holes 310 defined by the drain grate segment 310 , it is dispersed by the protrusions 420 extending from the horizontal surface 410 of the baffle segment 400 , there by reducing its velocity and its erosive impact on the contents of the basin. An example of a double-tiered baffle unit 610 is shown in FIG. 7B . This configuration provides an additional level of baffling to incoming storm water. An example of a retention basin wall 700 is shown in FIG. 8 . The segments employed in such a wall 700 are placed relative to ground surface 12 so that the notches 110 are at a level where storm water can flow from the surrounding ground surface 12 into the basin through the notches 110 (or out of the basin through the notches 110 when the basin is full). If it is desired not to have an exposed notch 110 on every segment 100 , selected segments 100 a can be inverted so that their notches 110 face downwardly. Several different configurations of the many different configurations of retention basins made possible with the present invention are shown in FIGS. 9A-9C . A substantially linear basin enclosure 900 is shown in FIG. 9A ; a substantially linear basin enclosure 910 including two oppositely-disposed baffle units 610 is shown in FIG. 9B ; and a cornered basin enclosure 920 is shown in FIG. 9C . A drawing of a rain garden 150 employing a representative embodiment is shown in FIG. 10 . As shown in FIGS. 11A-11B , in one embodiment, a T-shaped segment 1000 is used. The T-shaped segment 1000 includes a top edge 1002 and an opposite bottom edge 1004 . (However, as will be seen in FIG. 19A , the segment 1000 can be used in an inverted position.) Both the top edge 1002 and the bottom edge 1004 define a lifting bore 1250 . Each segment includes an internal bore 1016 that is used to maintain adjacent segments in linear alignment with each other. FIGS. 12A-12B show an S-shaped segment 1020 and FIGS. 13A-13B show an alternate T-shaped segment 1030 . As shown in FIGS. 14A-14B , shows one method of connecting segments to form a wall. In this embodiment, a bottom segment 1000 is placed in a desired location and then pins 1040 , such as a steel dowel, are placed in the internal bores 1016 of the bottom segment 1000 a . The pins 1040 maintain the alignment of the segments 1000 . Top segments 1000 b and 1020 are then lowered into place so that the pins 1040 fit in their internal bores 1016 . Curved S-shaped segments 1050 are shown in FIGS. 15A-15B and FIGS. 16A-16B show curved T-shaped segments 1060 (in an inverted position). A basin 1060 that is made from both curved segments 1050 and straight segments 1020 is shown in FIG. 17 . One method of stabilizing a wall of a bio-retention basin is shown in FIGS. 18A-C . In this method, each segment 1000 includes a side edge that includes a first vertical edge portion 1248 having a bottom from which a step edge portion 1240 extends laterally to a distal end. A second vertical edge portion 1246 extends downwardly from the distal end of the step edge portion 1240 . The internal bore 1016 opens to the step edge portion 1240 . A lateral groove 1242 may also run across the step edge portion 1240 . The segments 1000 are held in alignment with each other and are stabilized in the soil with an anchoring system 1210 . The anchoring system 1210 includes an elongated eyebolt 1224 that includes an eye portion 1225 that is disposed about the about the metal pin 1040 and that fits in the lateral groove 1242 . A metal plate 1226 is bolted to the eyebolt 1224 with a nut 1228 . Sufficient torque is applied to the nut 1228 so that the eyebolt 1224 applies sufficient tension to the metal pin 1040 and so that the plate 1226 applies sufficient force to the segments 1000 to keep them in a substantially fixed spatial relationship. An earth anchor 1210 is used to provide lateral support to the segments 1000 . The earth anchor 1210 includes a chain 1230 (or a cable) with one end coupled to the eyebolt 1224 (e.g., with a second nut). An anchoring shape 1236 is coupled to the opposite end of the chain 1230 . The anchoring shape 1236 is driven into the soil and provides a surface that resists movement within the soil. As shown in FIG. 20 , the anchoring shape 1236 can include a rod portion 1280 and a transverse portion 1282 that is hingedly attached to the rod portion 1280 . The transverse portion 1282 is initially in lateral alignment with the rod portion 1280 while the anchoring shape 1236 is driven into the soil and then is in a second position that is aligned transversely relative to the rod portion so as to provide resistance to slippage once the anchoring shape is disposed in soil. Typically, the anchoring shape 1236 is pounded into the soil with a steel rod and then the transverse portion 1282 moves into the second position as a result of soil resistance resulting from backwards movement of the anchoring shape 1236 . Once the anchoring shape 1236 is securely in place, the chain 1230 can be tightened to maintain strain on both the eyebolt 1224 and the anchoring shape 1236 . In one example of an alternative embodiment, an anchoring auger (which is screwed into place rather than pounded) can be used as an anchoring shape. As shown in FIGS. 19A-19B , segments 1000 can be installed by screwing lifting bolts 1252 into the lifting bores 1250 , attaching cables 16 to the lifting bolts 1252 and lifting the segment 1000 from a truck with a crane 14 and lowering it into an excavation 10 . Once the segments 1000 are installed, the lifting bolts 1252 are removed and the excavation 10 is backfilled to the ground surface 12 . While the lifting bores 1250 can be filled in with a material such as patching cement or silicone, they can be used to anchor post installation attachments 1260 , which can be bolted to the segments 1000 with bolts 1262 . A few examples of post-installation attachments, commonly found in the urban environment, that can be bolted to the segments 1000 include: a bench; a sign; a waste receptacle; a shelter; an enclosure; a streetlight; a traffic light; a bicycle rack; a newspaper vending box; a bollard; a fence; and many other types of attachments. The embodiments disclosed herein have the advantages of being easy to transport, inexpensive and they can be arranged in many different layouts to accommodate the available geometry of a specific site. They also have the advantage of being easily modified to allow for changes in design. The above described embodiments, while including the preferred embodiment and the best mode of the invention known to the inventor at the time of filing, are given as illustrative examples only. It will be readily appreciated that many deviations may be made from the specific embodiments disclosed in this specification without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is to be determined by the claims below rather than being limited to the specifically described embodiments above.	A retention basin includes interlocking concrete vertical wall segments engaged with adjacent segments. Each segment has a vertical wall and a top edge that defines a lifting bore that is complimentary in shape to a removable lifting bolt that is configured to provide a lifting attachment point for a lifting cable and an internal bore in alignment with the internal bore of an adjacent segment. A pin is disposed in the internal bores to maintain the segments in alignment. An eyebolt includes an eye portion disposed around the pin. A plate is bolted to the eyebolt and against the vertical walls of two adjacent segments to maintain the two segments in a spatial relationship. An earth anchor is buried in the soil to provide lateral support to the segments. A post-installation attachment is affixed to the lifting bore of at least one segment.	8
This is a continuation of application Ser. No. 732,360, filed May 8, 1985 now abandoned. TECHNICAL FIELD The present invention relates to a method and apparatus for constructing structures, and more particularly to a method and apparatus for utilizing substantially identical structural cells and interconnecting the same to form resilient structures of changeable buoyancy. BACKGROUND ART In the past, structures for use on or in bodies of water have typically been cast in place on dry land, and then floated to the resident site and then sunk into position. Typical of these structures is that shown in the booklet published by the Prescon Corporation of San Antonio, Tex. and entitled Freyssinet Offshore, 1976. This reference discloses a number of offshore drilling platforms which are constructed of prestressed, cast in place arrays of columns which are surrounded by a perforated breakwater wall. A significant disadvantage of such a structure is the requirement that the structure be cast in place and floated as a whole to the eventual resting site. Further, the overall shape of the platform requires complex configurations of posttensioning tendons. The large size of the finished platform presents a multitude of logistical problems in transporting the platform to its eventual resting site. Further, because such platforms are essentially a single structure, they are typically custom designed for the particular site. Finally, the customized nature of each of these platforms tends to maintain the cost of the platforms at a high level. In known platforms with or without undersea storage tanks, such platforms are built of steel or posttensioned prestressed concrete. In such structures the tendons are primarily circular or curvilinear and of medium size. The tendons are forced, by the circumvolutions of the concrete, into many lengths and diameters and complicated intersections. SUMMARY OF THE INVENTION These and other problems and disadvantages of previous waterborn structures are overcome by the present invention of a method and apparatus comprising a structure which includes a plurality of substantially identical structural cells, each comprising a parallelepiped, such as a cube having concrete walls of a specified thickness which enclose a hollow interior. As such, each cube is floatable in water when the interior is filled with air. In the structure, a plurality of walls of each cube are juxtaposed into registration with the walls of adjacent cubes. Means are provided for maintaining the juxtaposed walls in contact with each other. Means are also provided which communicate with each cube for controllably filling liquid into or evacuating liquid from the cubes so as to modify the buoyancy of the concrete structure. In a preferred embodiment of the present invention each of the walls of the cube are constructed so as to accommodate posttensioning tendons therethrough so that appropriate posttensioning tendons can be extended through each of the walls of the cubes which are positioned in common planes, said tendons being placed under tension to posttension each of the walls of each cube in at least two dimensions. A three-dimensional posttensioning is thus provided by this structure. Structures constructed out of these structural cells and with multidimensional posttensioning by way of tendons passing inside and through the cell walls provide a resilient structure of high strength. A feature and advantage of the invention is its lower first cost. Another advantage is zero or low maintenance of the tendons if the tendons are oil filled. Further, there is excellent response of the structure to forces supplied by the elements or seismic loads. It is to be understood that the present invention permits the building of structures from standard cells which cells permit the application of three-dimensional posttensioning to the structure. The present invention provides hollow parallelepiped-like elements, such as cubes, that can be safely connected together in any medium, to construct a myriad of differently shaped megastructures. In addition, such structures can be added to or subtracted from to provide overall structures of different sizes and shapes. It is therefore an object of the present invention to provide a method and apparatus for constructing structures of substantially identical structural cells. It is another object of the present invention to provide a method and apparatus for constructing structures of substantially identical structural cells wherein the structural cells are posttensioned against one another through common tendons which extend within the walls of each of the structural cells. It is another object of the present invention to provide a method and apparatus for constructing a structure which can be easily expanded or reduced in size by the addition or subtraction of substantially identical structural cells. It is a further object of the present invention to provide a method and apparatus for constructing a structure of identical structural cells which are posttensioned against one another so as to provide a resilient structure of high strength. These and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates two structural cells in accordance with the present invention. FIG. 2 illustrates a horizontal cross-sectional view of an undersea tank constructed in accordance with the present invention. FIG. 3 is an elevational view of a petroleum drilling platform and an undersea tank constructed in accordance with the present invention. FIG. 4 illustrates three structural cells of the present invention with tendons contained through tubing that couple with each other along their length. FIG. 5 illustrates the structural cells of the present invention joined to form a floating platform. FIG. 6 illustrates the structural cells of the present invention joined to form an atoll. FIG. 7 illustrates the structural cells of the present invention which are joined to form a fence anchored to the bottom of a body of water for deflecting floating objects, such as icebergs. FIG. 8 shows a top view of the structural cells of the present invention joined together to form a fender for deflecting floating objects, such as icebergs. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, substantially identical structural cells are coupled to one another to form larger structures. These structural cells are rhombic or parallelepipedic elements. These include right-angled parallelepipeds, namely parallelepipeds which have right-angled corners, such as cubes. Preferably these elements are cubic and have walls which enclose a hollow interior. Preferably the cubes are constructed of concrete and are 60 feet on a side. The walls of the cubes are of uniform thickness and preferably 4 feet thick. A cube of this structure will float even in fresh water. It is to be understood that hollow concrete elements of dimensions proportional to those discussed above will also satisfy the requirements of the present invention. The cubes or elements are connected together by tendons inserted into tubing or threaded oil pipes, of the type used for oil drilling, which tubing or pipe extend within the walls of the cubes. Referring to FIG. 1, two cubes are shown juxtaposed to one another in accordance with the present invention. The solid lines in the figures represent the external edges of the cube, while the dotted lines illustrate the hollow portion of each cube. In order to simplify the description, only a single tendon is shown extending through a particular wall for a particular dimension, it being understood that in practice a multiplicity of tendons will extend through each of the walls of a cube for each dimension of the wall. Thus, for cube 10, and upper wall 12, tendon 14 extends through wall 12 along one dimension of the wall, while tendon 16 extends through wall 12 in an orthogonal dimension of the wall. Note that tendon 14 also extends through upper wall 18 of cube 20. Likewise, for bottom wall 25 of cube 10 and bottom wall 24 of cube 20 tendon 26 extends therethrough along one dimension. For side wall 22 of cube 10 tendon 28 extends therethrough in an orthogonal direction. Similarly, with respect to side wall 27, tendon 30 extends therethrough in an orthogonal direction to that of tendon 26. It is to be understood that, in practice, each of the walls of a structural cell will have tendons extending therethrough in two orthogonal dimensions. While such a structure requires a large number of cables, for any particular structure the number of different lengths and size of cables requires will be limited. Further, the tendons extend along straight lines as opposed to curves. This makes the tensioning and securing of the tendons much simpler than in previous designs. As can be seen from FIG. 1, tendons 14 and 16 posttension those walls which lie in a common plane. Further, tendon 28 and the unlabelled tendon, both of which extend through wall 22, posttension walls in a common plane which is different from the common plane to which tendons 14 and 16 are parallel. Further, it can be seen that the posttensioning of these various common planes provides a posttensioning of the structure in three dimensions. In the preferred embodiment of the present invention concrete is the material from which the walls of each structural cell is constructed. Concrete has excellent strength under compression. When prestressed, concrete also provides excellent bending characteristics. Preferably, steel is utilized in the tendon to take advantage of its favorable tensile strength. Tendons suitable for use in the present invention are of the type described in U.S. Pat. No. 3,225,499. The structure shown therein permits anchor plates to be installed after the tendons have been placed in the structure or after the concrete is cured. Preferably, the tendons are not bonded with cement grout, but enveloped and coated with oil or grease. This permits the tendons to be removed for inspection in the future. Hollowness gives lightness and flexibility to the structural cells. Prestressing gives flexibility to the concrete of the cells. The cells should be smooth and leveled at their surface of contact with other cells. In the preferred embodiment of the present invention, in addition to the joining of the cells by the posttensioning tendons, the outer periphery of each wall surface is bonded to the adjoining wall surface periphery. Preferably the width of this perimeter is 4 feet. The tendons are disposed inside the walls of the cells in both directions and uniformly. The tendons are preferably arranged in the middle of the width dimension of the 4 foot thick walls and extend straight through the walls. In the same wall, they are also at 90° from one another. The cross each other by being displaced, preferably, one-half cable diameter on each side of the C.G.C., i.e. center of gravity of concrete, of the concrete slab or wall. A number of cells are connected together by threading the tendons into and through their preassigned holes. The tubes can be tubing or pipe steel. By providing posttensioning tendons in each of the walls of each cell, a posttensioning in three dimensions can be achieved. FIG. 2 illustrates a plan section of an undersea tank constructed in accordance with the present invention. The double solid lines represent the junction between structural cells, while the single solid lines represent the tendons extending through the walls of the cells. Thus, the tank of FIG. 2 is preferably constructed to have eight structural cells along each dimension of the tank. For example, a structural cell 32 occupies the upper left-hand corner of the plan view of the second shown in FIG. 2. Tendon 34 passes through the upper walls of cells 32, 36, 38, 40, 42, 44, 46 and 48. The other tendon which passes in an orthogonal direction through the upper wall of cell 32 is tendon 50. This tendon extends through the upper wall of the cells lying along the left-hand edge of the horizontal plan section shown in FIG. 2. Steel piers, piping, or drilling conductors are provided in the position of the structural cells located towards the corners of the platform. For example, steel piers 52 and 54 provide space for drilling conductors to extend through the storage tank down into the floor of the body of water. Steel piers 56 and 58 can provide passageways for piping which access the different levels of the storage tank. While not specifically shown in FIG. 2, it is to be understood that posttensioning is provided in the walls of each cell in the vertical dimension of the storage tank. Referring to FIG. 3, an elevation of the storage tank constructed in conjunction with an oil drilling platform is shown. The steel piers 54 and 58 are shown extending from above the surface of the body of water where they support the drilling platform 60, down and extending through the storage tank 62, and into the seabed 64. As with FIG. 2, the double solid lines indicate the junctions between adjacent structural cells, while the single solid lines indicate the tendons through the walls of each of the cells. As can be seen from FIG. 3, the storage tank showing the vertical dimension is formed from eight layers of structural cells. This provides a storage tank, in the preferred embodiment, of a height of 480 feet, a width of 480 feet, and a depth of 480 feet. With such a structure as in FIG. 3, certain of the cells can be used at times as ballast, while other of the cells can be used as storage for oil, water, or air. In the preferred embodiment to the present invention, all cells can be communicated with to selectively fill or empty each of the cells. Referring to FIG. 4, the intercommunication of each of the structural cells, and the routing of the tendons through the walls of the cells, will be described in greater detail. FIG. 4 illustrates the use of tubing 65 or piping which are positioned in the walls of each of the structural cells. The positions of the tubing in any particular wall is selected so that when the cell in which the wall is located is positioned adjacent another cell, the tubing in that particular wall will come into registration with a corresponding tubing in the corresponding wall of the adjacent cell. Thus, a tendon, for example 66, can pass via the tubing through each of the walls of the adjacent cells, for example cells 68 and 70, and tubing portions 72 and 74, respectively, or the tendons can be passed through preformed holes. Pipes for water or crude oil are extended through vertical columns of the structural cells. A pump at the bottom of the column provides the motive force for moving liquid into or out of each of the cells. In one embodiment to the present invention, the piping for passing liquid extends between adjacent cells by way of ports which have a diameter larger than the pipe. Thus, liquid in a particular cell can flow to the next cell below through the ports. In FIG. 4, liquid is drawn out of the cells through the pipe, e.g., 76, and to the top of the column. Pump 78 pumps liquid from the bottommost cell into pipe 76. Liquid in the cells above the bottommost cells flow through the ports 80 and into the bottommost cell. When such an arrangement is used, the outer periphery of adjoining walls for each cell are bonded together to form a fluid-tight cell. Thus, even though a port 80 has been opened between adjacent cells, the presence of the bonded outer periphery 82 of adjoining cells prevents liquid from being expelled from between the adjacent cells. In one embodiment to the present invention, each stem of the liquid transporting pipes is threaded and connected at the joint of the cells. The oil and water pipes can also be disposed at the center of the square surfaces of the cubes, or at other points. Further, the bonding of the wall of the cubes at the outer periphery thereof can be performed by way of epoxy concrete. The tremie technique can be used to control water tightness completely. In practice, the cells are formed individually and assembled into a structure either on land or at the drilling site. The cells can be placed floating in the water and transported out to the site. There the entire structure can be assembled. For implantation, the placement is controlled by filling certain interconnected cells with water. The assembly can also be relocated when it is desired to change location of the structure by pumping liquid out of the structure. The basic cell can be fashioned into megastructures such as iceberg fences, iceberg fenders, atolls, flat floating cellular platforms for supporting airports, cities, nuclear plants, and the like, and artificial lagoons or toys. The toys can be of a type similar to erector sets and constructed of wood or plastic with a small number of holes to thread the wire tendons through and to consolidate any shape or structure. Such structures can include bridges, vessels, and other models. Prestressing/posttensioning strengthens the nuclear concrete intrinsically and extrinsically. Water pressure applied when the cell is submerged also provides posttensioning to the cell. The cells are thus made water proof more easily. The compressive strength of concrete increases by 1,000 psi per 500 feet of depth. A solid concrete piece at 3,000 feet depth is completely unbreakable in compression under hydrostatic or triaxial pressure. The triaxial pressures do not have to be equal in each dimension. For hollow concrete elements, the prestressing force needed increases to 600 feet, then decreases to zero below 3,000 feet. There is a fundamental difference between posttensioning in two dimensions (biaxial) and posttensioning in three dimensions (triaxial), as is used in the structures of this invention. One easy way to apply three-way prestressing is by immersion deep into sea water. Another is through the use of expansive cement and properly placed reinforcements. In this invention, the three-way dimensional prestressing is applied by tendons similar to those in the other two dimensions. At great depth, advantage may be taken of the water hydrostatic pressure. Under triaxial pressure or prestressing, an element of concrete acquires fine tensile properties and behaves as if it could resist tension and higher compressive strength. If f c is the allowable unrestrained compressive stress, p M =maximum principal stress p m =minimum principal stress x=p M /f c y=p m /f c then the concrete is stable if: ##EQU1## If the concrete element is placed in a biaxial or triaxial tension field, it behaves as under simple tension. In accordance with the present invention, the above relationship permits posttensioning in the third dimension to be easily determined. Thus posttensioning in the third dimension becomes possible by becoming thus calculable. Also the total pressure over a side area of the cells is transmitted by mullions to girders of the cells. In the cubic toys, each cube is held by 12 wires not necessarily under tension or by rubber bands. It is to be understood that in accordance with the present invention, the amount of compressive forces supplied by the tendons can be selected so that a part of the total force requires to stabilize the structure and so that the water pressure supplied by the surrounding water can supply the remainder of the forces. Referring to FIG. 5, a floating platform 84 is shown. Here, the structural cells are formed into a planar layer, with posttensioning in the orthogonal directions within the planar layer. As such, a floating platform is formed which resists buckling and deformation by the changing surface characteristics. Referring to FIG. 6, an atoll 86 is shown. The atoll deflects currents 88 and 90 within the body of water. The cells of the atoll 86 are partially filled with water so that the atoll is partially submerged. In turn, the atoll 86 provides a calm internal body of water in comparison to the external body of water. FIG. 7 illustrates an iceberg fence constructed from cells of the present invention. The iceberg fence if formed from a planar layer of the structural cells. One edge of the layer is anchored in the seabed 64. Due to the resilience of the structure provided by the posttensioning, the iceberg 94 is permitted to deform the planar layer 92 as opposed to destroying it. Finally, referring to FIG. 8, an iceberg fender 96 is illustrated. The fender is formed by forming two planar layers of the structural cells and joining the layers at a common edge. The layers are angled with respect to one another so that a "V" is formed. The "V" structure is turned on its side and faced into the current 98 so as to create a wedge which deflects the current to either side of the fender 96. As such, iceberg 94 will be deflected in like manner. The terms and expressions which have been employed here are used as terms of description and not as limitations, and there is no intention, in the use of such terms and expressions, of excluding equivalents of features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the invention claimed.	An improved method and apparatus for structures comprising a plurality of substantially identical structural cells, each comprising a cube having concrete walls of selected or calculated thickness. The walls enclose a hollow interior so that each cube is floatable. The walls are constructed so that tendons can be passed inside the walls in orthogonal directions. The tendons are tensioned after the structure has been assembled so as to prestress all walls along at least two dimensions so as to provide a three dimensional posttensioning effect on the concrete in the structure. Means are also provided which communicate with each of the cells for selectively filling or emptying each cell with liquid. The cells can be joined together at a drydock on land or at sea to form the structure.	4
This is a continuation of application Ser. No. 928,412, filed July 16, 1978, now abandoned. BACKGROUND OF THE INVENTION This invention relates generally to a device for controlling hydraulic working circuits and, more specifically, it relates to a control device that is applicable as a travel regulating valve for controlling a hydraulic power lift unit in a tractor. The device is of the type where a mechanically actuated slide of a preselector valve cooperates with a slide of a main selector valve that in response to the position of the preselector slide resumes a neutral position or an operative position. In the neutral position the main selector valve brings the supplied pressure fluid into a non-pressurized circulation whereas in the operative position the flow resistance in the non-pressurized circuit is increased and the pressure is applied to the load. Hydraulic control devices of this type are known, for example from the German Pat. No. 1,928,896 and include besides the preselector valve slide and the main valve slide an auxiliary slide that is arranged in an axial boring of the main valve slide. In this known control device the auxiliary slide contributes to the pressure relief of a control chamber arranged in the main control slide. This prior art device is supposed to prevent by means of jumping movement of the auxiliary slider the occurrence of such a choking action in which an amount of pressure oil delivered by the pump is capable of leaking over the pressure relieving openings when pressure conditions have correspondingly increased so that the pump has to operate at an unduly increased pressure. This choking action or process, called "tight choking", may very quickly result in breakdown of the pump. However, in the prior art control devices the tight-choking is avoided during the pressure building phase that means during the displacement of the slider of the preselector valve from the neutral position to a lifting position, but there still remains the possibility that during the displacement of the preselector slider from working or lifting position to the neutral position pressure conditions may result that can induce the tight choking effect. Moreover, the known control device has the disadvantage that the tolerances and mutual arrangement of ports and control edges in the borings and on the slides of the valve, are critical. Above all, the prior art control device has the disadvantage that it is very expensive because in addition to the auxiliary slide there are necessary additional control shoulders, ports and control openings for diminishing the danger of tight choking. SUMMARY OF THE INVENTION It is therefore an object of this invention to avoid the disadvantages of prior art control devices of this type. More particularly, it is an object of the invention to provide an improved control device for hydraulic power circuits that are simple and compact in structure. Another object of the invention is to provide an improved control device that eliminates the additional auxiliary slider with corresponding opening, ports and control shoulders that hitherto had been necessary for preventing the tight choking effect. A further object of the invention is to provide means that make it possible to improve existing control devices without difficulties and with minimum cost. An additional object of this invention is to provide such an improved control device that prevents the tight choking effect not only during the movement from the neutral position to the operative position but also during the movement of the preselector slide from lifting or working position in the direction to neutral position. Furthermore, an object of this invention is to provide an improved control device in which the tolerances and complexity of control edges and ports is relatively easy to be mastered from the production point of view. In keeping with these objects, and others which will become apparent hereafter, one feature of the invention resides, in a control device of the aforementioned type, in a combination which comprises means for avoiding the tight choking effect resulting from pressure changes in a control chamber when changing the position of a preselector valve, the means including a recessed section provided on the preselector slide in the range of the control chamber and defining lateral end faces that are subject to pressure changes in the control chamber and a bottom portion the cross section of which is reduced to such an extent as to exert elastic extension in longitudinal direction when the end faces are subject to increased pressure, thereby completing the closing of the passage between the control chamber and a pressure chamber of the main selector valve. In a preferred embodiment, the end faces in the recess on the preselector slide that are subject to effective pressure changes, have equal surfaces. The slide of the main selector valve is arranged for movement within a blind boring in the slide of the preselector valve whereby the pressure chamber for the main valve results between the end surface of the blind bore and the end surface of the main slide. The bottom portion in the recess of the preselector slide is arranged in the range of movement of the main selector slide and is provided with openings that connect the control chamber with pressure relief spaces. The preselector slide is coupled to a mechanical control linkage by means of which either the neutral or the working position of the selector valve system can be adjusted. Preferably, the preselector slide is provided with a second recess extending between the first mentioned control edge and a second control edge that provides an adjustable passage between the pressure chamber for the main selector valve and a pressure relief space. In the coaxial arrangement of the preselector slide and main selector slide, the length of the elastically extensible bottom portion of the recess in the preselector slide equals preferably to the diameter of this recessed portion and the wall thickness of the bottom portion equals preferably one-third of the wall thickness of the remaining portions of the preselector slide. The second recessed part of the preselector slide is dimensioned so as to register with an opposite shoulder in the valve boring when the preselected slide is brought to a working position of the device. The device of this invention is applicable as a regulating device for controlling a servo motor in an agricultural machine such as a tractor or a harvester thresher. The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section of a schematic representation of a control device in its neutral position; FIG. 2 is a sectional cut-away view of a part of the device of FIG. 1 showing the preselector slide in the beginning of its lift position; and FIG. 3 is a sectional cut-away view of a part of the device of FIG. 1 showing the preselector slide in the end of its lift position. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a control device 10 having a housing 11, a boring 12 for accommodating a preselector slide 25. The end portions of the boring 12 communicate respectively with pressure relieving spaces 15 and 16 connected to pressure oil tank 14 and the central part of the boring 12 is extended in diameter to form an annular chamber 13. The chamber 13 communicates with pressure fluid supply pipe 17 through which a pressure medium from pump 18 is delivered into the chamber and further it communicates via working pipe line and via a non-return valve 21 with a hydraulic power lift unit 22 that can be relieved through a return pipe line 23 connected through lowering control valve 24 to a pressure relief space 16. The preliminary control or preselector slide 25 is urged by means of a pressure spring 26 arranged in the pressure relieving space 15 into slidable contact with a setting member 27 that at the other side is in slidable contact with a lever 28 controlled by a regulating rod 29. The position of the setting member 27 and thus the position of the slide 25 is mechanically adjustable by means of lever 31. As shown in more detail in FIG. 2, the preselector slide 25 is provided with two annular grooves 32 and 33 dividing the slide surface into three separate sections 34, 35 and 36. The preselector slide 25 has an axial blind boring 37 which accommodates for sliding movement a main selector slide 39 that is also provided with an axial blind boring 55. The main selector slide 39 extends approximately between the second sector 35 and the third sector 36 and the remainder of the blind boring 37 between the first sector 34 and the end surface of the main selector slide 39 defines a control chamber 41. The control chamber 41 communicates through a port 42 with the first annular groove 32 of the preselector slide. The end surfaces of the first annular groove 32 define with respective sectors 34 and 35 control edges 43 and 45 that cooperate with correspondingly spaced control edges resulting in the boring 12 between pressure relief space 15 and pressure chamber 13. If the preselector slide 25 is moved to the left, the first control edge 43 is out of register with the wall of pressure relief space 15 and creates an adjustable passage connecting the control chamber 41 through the port 42, the first annular groove 32 to the pressure relieving space 15. The movement of the preselector slide 25 is transmitted to the control valve 24 for lowering the lift unit 22 by means of a pin 44 connecting the slide 25 to the valve 24. The second sector 35 of the slide 25 defines as mentioned above a second control edge 45 that provides for an adjustable passage connecting the first annular groove 32 with the pressure chamber 13. The second sector of the slide 25 is relatively narrow so that the second annular groove 33 in the preselector slide 25 extends over the major part of the pressure chamber 13. The second annular groove 33 is deeper than the first annular groove and the thickness of its bottom wall 46 extending between lateral end surfaces 47 and 48 is selected so as to be extendable within elastic limits of the material of the preselector piston 25. In other words, the second groove 33 reduces the diameter of the slide 25 to such an extent that the narrow wall portion between the bottom 46 of the groove 33 and the inner wall formed by the axial boring 37 exhibits perceptible changes in its longitudinal direction when pressure changes take place in the pressure chamber 13 during the operation of the device. These changes in longitudinal direction remain however within the elastic limits of the material of the slide 25. In order to still increase these elastic changes in longitudinal direction, an opening is made in the bottom wall 46 so that the mass of the bottom wall is additionally reduced. The opening 52 and the passage 49 is controlled by the main selector slide 39 as it will be explained below. The main selector 39 is provided with an opening 53 communicating with the interior blind boring 55 and the upper part of the opening 53 is increased in diameter and provided with a sloping control edge 54. The inner blind boring 55 in which the pressure spring 38 partially projects, communicates with the pressure relieving space 16 so that it relieves pressure from the pressure chamber 13. Since the second surface sector 35 of the slide 25 is made relatively narrow, the length of the bottom section 46 of the groove 33 is relatively long and exceeds the diameter of the preselector slide 25 in the range of this section. As it has been explained above, the first control edge 43 and the second control edge 45 formed by end walls of the first annular groove 32 are designed so as to register with corresponding end surfaces of the flange in the housing 11. The operation of the control device is as follows: The position of the preselector slide 25 as illustrated in FIG. 1 corresponds to neutral position of the control device 10 during which pressure fluid supplied by the pump 18 flows through supply conduit 17, pressure chamber 13, passage 49 in the preselector valve 25 and the opening 53 in the main selector valve 39 into the blind boring 55 and therefrom through the pressure relieving space 16 into the tank 14. During this neutral circulation the control edge 54 in the upper part of the opening 53 in the main selector valve 39 chokes the relatively small pressure in the chamber 13 resulting from the neutral circulation of the pressure fluid. Through the open passage between the control edge 45 and the end surface of the pressure chamber 13, the pressure fluid enters through port 42 into control chamber 41 where it acts against the force of the spring 38 and keeps the main selector slide 39 in its open position as illustrated in FIG. 2. In this open position the pump 18 provides an almost unloaded circulation of the pressure fluid. If it is desired to lift the power lift unit 22, the lever 31 is operated counterclockwise so that the preselector slide 25 is moved to the left to the position as shown in FIG. 3. This position is attained also in the case of a lowering load (for example due to oil leakage) so that the control rod 29 is mechanically moved to the left and via lever 28 moves the slide 25 also to the left. In this position, the control edges 43 and 45 close the communication to the first annular groove 32 since they are in register with the assigned end surfaces of the opposite flange in the housing 11. In this aligned position of the control edges, the danger of the so-called tight choking exists. The tight choking means an equilibrium condition at which the main selector valve 39 chokes the otherwise nonpressurized circulation of the pressure fluid with a more or less increased effect so that the pump 18 has to deliver the entire stream of fluid against the correspondingly increased pressure in the return circuit and this overloading may cause a fast breakdown of the pump. In the event of the tight choking, pressure fluid leaks over the closed control edges 43 and 45 in such a quantity that the main valve 39 may resume a position at which it completely chokes up the circulation of the pressure fluid. In the device of this invention, the pressure increase resulting in the pressure chamber 13 at the beginning of the tight choking condition acts against the end surfaces 47 and 48 in the annular groove 33 in the slide 25 and causes, within the limits of elastic deformability of the material of the slide 25, the axial extension of the thin wall bottom section in the groove 33. It is important that this axial extension takes place only then when the controlling process has been initiated. The extension brings about only a further displacement of the first control edge 43 in the opening direction relative to the registering end face of the shoulder in the housing 11 and the displacement of the second controlling edge 45 in the closing direction relative to the assigned stationary end surfaces of the housing. In this manner a relatively large improvement of the operation of the selector valve system is attained and the occurrence of the tight choking is reliably eliminated. By designing a relatively long bottom part 46 of the second annular groove 33, a correspondingly increased extension of the thin wall bottom 46 can be achieved. The elastic extension can be increased by making additional material cutouts 51 thus increasing the stretchability of the material within its limits of elastic deformability. The same result, namely the elimination of the tight choking is achieved when the preselector slide 25 is moved from the lifting or working position in the direction to the neutral position whereby it moves past the position as illustrated in FIG. 2. In doing so, the decreasing pressure in the pressure chamber 13 causes the contraction of the section 46 in the second annular groove 33 and in a reversed order the control edge 43 more firmly closes the passage between the first annular groove 32 and the pressure relieving space 15 and the second control edge 45 is moved in the direction of the neutral position so that the neutral position is reached without the occurrence of the tight choking effect. For lowering the hydraulic power lift unit 22 is relieved in usual manner by means of the lowering valve 24. The invention as described above in the preferred embodiment makes it possible to construct a simple and compact hydraulic control device that eliminates the danger of the tight choking effect. It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. While the invention has been illustrated and described as embodied in a control device employing a coaxial arrangement of the preselector slide and the main selector slide, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. For example, the inventive idea is applicable in a construction using spatially separate preselector slide and main selector slide. In another possible modification instead of the second control edge 45 it is possible to use a choking passage for limiting the pressure fluid flow into the control chamber 41.	The control device is applicable as a hydraulic regulating valve for controlling a power lift unit of a tractor and comprises a mechanically actuated preliminary selector valve operable for reciprocal movement to close or open pressure fluid supply into a control chamber counteracting a reciprocal main pressure control valve that is spring loaded against the control chamber. To avoid permanent choking resulting from pressure changes due to the movement of the control edges, a section of the preliminary control slide is recessed to such an extent as to exert elastic extension when subject to increased pressure, the extension being within the limits of elasticity of the material of the slide.	5
BACKGROUND OF THE INVENTION The present invention relates to an automatic focusing camera. FIELD OF THE INVENTION Numerous compact cameras are equipped with automatic focusing devices. An automatic focusing device comprises a subject distance detecting device which is caused to operate as a result of depressing a shutter releasing button so as automatically to detect a subject distance and a lens positioning mechanism for moving and positioning an objective lens at a suitable focusing position according to the detected subject distance before a shutter is actuated. There are well known in the art various types of automatic subject distance detecting devices, for example active type or passive type automatic distance detecting devices. Active type automatic distance detecting devices which various compact cameras are equipped with are based on the principle of trigonometric range finding. For incorporating such an active type automatic distance detecting device in a compact camera, light projecting and light receiving means are provided which are spaced apart a distance equal to the base length of the automatic distance detecting device. Light projected from the light projecting means is partly reflected by a remote subject and received by the light receiving means through a lens. The optical axes of the light projecting means and the light receiving means are parallel to the optical axis of the objective lens of the camera. As the angle of incidence of light from the remote object on the light receiving means depends on the subject distance, the subject distance can be found by detecting on which one of a plurality of divisions of the light receiving means the light reflected from the object impinges. If a subject is at an infinite distance, the reflected light incident on the light receiving means is too weak in intensity and has a very small incidence angle. For example, if it were attempted to distinguish between two subjects one at an infinite distance and the other at a finite distance greater than 10 m from the camera, the light projecting means would have to have a very strong light emission and the light receiving means would have to consist of minute divisions of light receiving elements, resulting in an expensive automatic distance detecting device. In attempting to overcome this problem heretofore, the greatest focusing distance to which the focus of an objective lens could be automatically adjusted was for example 12 m from the objective lens, since the objective lens would be in focus on a subject at a distance between that limited finite distance, for example 12 m, and infinity, thanks to the depth of field of the objective lens. A problem associated with the above-described automatic distance detection device is that it is unfavorable to subjects such as landscapes whose subject distances generally are infinite. This is true because, although the objective lens could focus on a subject at infinity, the farthest automatically settable focusing distance is a finite distance, for example 12 m, and so an enlarged image of the landscape at an infinite distance will be produced which will be blurred. Another problem, which is peculiar to the active type subject distance detecting devices, is wrong distance detection. For example, when photographing a landscape at an infinite distance, from behind a transparent window glass, the automatic distance detecting device sometimes makes a wrong decision on subject distance because of reflected light from the window glass. In general, because the depth of field of an objective lens becomes wider with distance, it is hard to detect a precise subject distance of a subject at infinity even by a focusing device rather than by an active type distance detecting device or a range finding device such as a device of the type which detects the sharpness of an image of the subject. OBJECT OF THE INVENTION It is, therefore, an object of the present invention to provide an automatic focusing camera in which an objective lens is reliably adjusted to infinity when photographing a subject at infinity such as a landscape. SUMMARY OF THE INVENTION The above and other objects of the invention can be accomplished by providing an automatic focusing camera equipped with lens positioning means for positioning an objective lens at an infinity position independently from a subject distance detected by an automatic subject distance detecting means. The lens positioning means is caused to operate by means of an externally operable member which is operated when photographing a subject at infinity such as a landscape. According to a preferred embodiment of the present invention, when the externally operable lens positioning means is operated, the objective lens is adjusted to an infinity position to focus on a subject at infinity. Because the positioning of the objective lens to infinity is effected independently from the automatic subject distance detecting device, the objective lens can be correctly positioned at infinity without any influence of noise from the automatic subject distance detecting device, thereby providing a well focused sharp image of the subject at infinity. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the present invention will become apparent to those skilled in the art from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which: FIG. 1 is a perspective view showing an automatic focusing compact camera embodying the present invention; FIG. 2 is a block diagram showing the circuit used in the camera of FIG. 1; and FIG. 3 is an explanatory illustration showing the relationship between suitable focusing lens position and the depth of field of an objective lens. DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, there is shown a compact camera equipped with the automatic focusing device of the present invention. As shown, a camera body 1 has in its front wall an objective lens 2 centrally positioned, a finder frame window 3 above the objective lens 2, and a strobe light emitting window 4. Provided in the top wall of the camera body 1 is a shutter release button 5. All these elements are well known in the art. Above the objective lens 2 there are two lenses, namely light projecting and light detecting lenses 11 and 14, disposed on opposite sides of the objective lens 2, these lenses 11 and 14 being separated a distance equal to the base length L of an automatic range finding device which will be described in detail later. The camera body 1 is further provided on its back wall with a pushbutton 8 for setting the objective lens 2 to an infinity mode in which the objective lens 2 is focused at infinity. Reference is now had to FIG. 2 illustrating the principle of the automatic focusing system according to the present invention. As shown, the automatic focusing device mainly comprises an automatic range finding device and a focusing device. The automatic range finding device includes light projecting means 6 and light detecting means 7. The light projecting device 6 has a light emitting element 12 such as an infrared light emitting diode disposed behind the light projecting lens 11 for projecting light toward a remote subject 23 to be photographed through the projecting lens 11. The optical axis 11a of the light projection lens 11 is parallel to the optical axis 2a of the objective lens 2. On the other hand, the light detecting means 7 has a color filter 15 for passing infrared light having a wavelength, for example, longer than abut 700 nm and a light sensing element 13, both of filter 15 and light sensing element 13 being disposed behind a light detecting lens 14. The optical axis 14a of lens 14 is parallel to the optical axis 11a of the light projecting lens 11, and hence the axis 2a of the objective lens 2. The light sensing element 13, which is placed in the focal plane of the objective lens 2, comprises a plurality, for example in this embodiment five, of smaller divisions of light receiving elements 13a to 13e arranged in the direction of the base length L. An operation circuit 16 connected to the light detecting element 13 executes an operation based on a distance signal provided any one on the smaller divisions of light receiving elements 13a to 13e of the light detecting element 13 to provide a controller 17 comprising a micro- processor unit with a position signal. Upon receiving the position signal from the operation circuit 16, the controller 17 actuates a driver 18 to control the rotation of a motor 19, so as to move the objective lens 2 spirally back or forth to place it in a focused position according to the position signal. A light measuring circuit 25 is connected to the controller 17 through an A/D converter 26. This light measuring circuit 25, which may take the form of any of known circuits including a light detecting element for effecting an automatic exposure control (AE), detects the brightness of the remote subject 23 to provide a brightness signal which in turn is sent to the controller 17 after being converted into a digital signal by the A/D converter 26. In the controller 17 the brightness signal in a digital form is subjected to a programmed operation and then sent as a light emission signal for a strobe to an AND circuit 28 through a line 27. This light emission signal has a signal level of high (H) when the brightness of the remote subject is lower than a predetermined level and artificial illumination light is needed or a signal level of low (L) when the remote subject is bright enough. Connected to the AND circuit 28 are an infinity signal generating circuit 21 through an inverter 29 and a shutter release signal generating circuit 22. The shutter release signal generating circuit 22 generates a shutter release signal of a level high (H) when the shutter release button 5 is depressed and a signal of a level low (L) when the shutter release button 5 is not depressed. The infinity signal generating circuit 21 generates an infinity mode signal of a level high (H) when the pushbutton 8 is pushed to set the camera to the infinity mode or a signal of a level low (L) rather than the infinity mode. Therefore, the AND circuit 28 provides a signal of a level high (H) as a result of the depression of the shutter release button 5 only when the camera is set to a normal focusing mode and the remote subject is judged to have a brightness greater than the predetermined brightness by the controller 17. The high level signal from the AND circuit 28 triggers a strobe circuit 30 to deliver a flash. As is shown in FIG. 3, the objective lens 2 has five focus positions S1 to S5 corresponding to the respective light sensing elements 13a to 13e of the light detecting element 13 in the normal focusing mode and one special or infinity focus position S6 in the infinity mode. When the camera is set to the normal focusing mode, the operation circuit 16 provides the controller 17 with a position signal according to the output signal from the light detecting element 13; the controller 17 actuates the driver 19 to cause the motor 19 to rotate, so as to move the objective lens 2 to a selected one of the focus positions S1 to S5. When the pushbutton 8 is operated to set the camera to the infinity mode, the infinity signal generating circuit 21 provides the controller 17 with an infinity focusing signal; the controller 17 actuates the driver 19 to cause the motor 19 to rotate, so as to move the objective lens 2 to the infinity focus position S6. As is shown in FIG. 3, the objective lens 2 can be selectively adjustable to the focusing positions S1 to S5 according to the light sensing elements which receive light from the remote subject. For example, if the light receiving element 13d receives light, the objective lens 2 is adjusted to the focusing position S4, for example a subject distance of 3.14 m., When the objective lens 2 is adjusted to the focusing position S4, the objective lens 2 is in focus for any subject in a distance range between about 2.3 and 5.0 m when the aperture is fully open, owing to the depth of field of the objective lens 2. Taking an example for easier understanding, when reflected light from the remote subject 23 is detected by the divisional light sensing element 13d of the light detecting element 13, an output from the divisional light sensing element 13d is operated by the operation circuit 16 so as to provide the controller 17 with a position signal representative of the fourth zone of the finite subject field. Correspondingly to the fourth zone position signal, the controller 17 causes the driver 18 to rotate the motor 19 so as to move the objective lens 2 to the position S4. The position S4 is, for example, the lens position in which an object 3.14 m from the camera is in focus. If in fact the objective lens 2 is focused on a subject at the distance corresponding to the position S4, the depth of field of the objective lens 2 is between 2.3 and 5 m when the aperture is fully opened. Owing to the depth of field of the objective lens 2, by positioning the objective lens in any one of the positions S1 to S5, the objective lens 2 can be well focused on a subject at any distance between the closest distance and infinity. When the objective lens 2 is adjusted to the position S6 which is selected independently of the outputs from the light sensing elements 13a to 13e, the objective lens 2 is focused on infinity. When the objective lens 2 is adjusted to the position S6, the near end of the depth of field of the objective lens 2 is about 12 m. In operation of the automatic focusing camera constructed and described above, the shutter button 5 is depressed half way. As is described above, as a result of the halfway depression of the shutter release button 5, a release signal is generated by the shutter release signal generating circuit 22 and sent to the controller 17. If the pushbutton 8 is not pushed, the light projecting means 6, specifically the light emitting element 12, projects light toward the subject 23 to be photographed through the projecting lens. The light reflected from the remote subject 23 is received by a light detecting element 13 of the light detecting means 7. If the remote subject is for example 3 m from the camera 1, the reflected light is received by the light sensor element 13d. The output from the light sensing element 13d is received by the operation circuit 16 and then sent as a lens positioning signal to the controller 17. According to the lens positioning signal, the controller 17 causes the driver 18 to rotate the motor 19, moving spirally and thus axially the objective lens 2 to the lens position S4 (3.14 m). As is shown in FIG. 3 and described previously, the objective lens 2 positioned at the lens position S4 can correctly focus on a subject in a distance range between 2.32 m and 4.95 m because of the depth of field thereof. Therefore, the object lens 2 can well focus the remote subject 23 at a subject distance 3.0 m. After the objective lens 2 has automatically been adjusted to focus on the remote subject 23, the shutter button 5 can be fully depressed. For an actual exposure, the shutter button 5 is depressed fully to cause first the light measuring circuit 25 and the A/D converter 26 to detect the brightness of the subject 23. If a brightness level higher than a predetermined level is detected, the shutter is actuated under the control of an automatic exposure control system which is well known in the art and, therefore, a description is not needed. In such a way, an exposure is completed. On the other hand, if the detected brightness level is lower than the predetermined level, the controller 17 provides the connecting line 27 with an H level signal. As a result, the AND circuit 28 receives three H level signals from the controller 17, the infinity signal generating circuit 21 through the inverter 29, and the shutter release signal generating circuit 5, thereby actuating the strobe trigger circuit 30 when the shutter release button is fully depressed so as to trigger the strobe. In this way, a flash exposure is made. When photographing a landscape as a subject of which the subject distance is generally infinity, the shutter button 5 is depressed half way while the push button 8 is pushed. Consequently, the controller 17 receives an infinity signal from the infinity signal generating circuit 21 upon receiving a shutter release signal from the shutter release signal generating circuit 22. Upon receipt of the shutter release signal and the infinity signal, the controller 17 causes the driver 18 to rotate the motor 19 so as automatically to move the objective lens 2 to the lens position S6, without detecting the distance of the subject. At the end of movement of the objective lens 2, the shutter button 5 is allowed to be fully depressed. If in fact the shutter button 5 is fully depressed, the light measuring circuit 25 and the a/D converter are actuated to detect the brightness of the subject. When a brightness level higher than the predetermined level is detected, the shutter is automatically actuated under the control of the automatic exposure control system so as to make a sharp image of the subject at infinity. When the shutter button 5 is depressed while the pushbutton 8 is pushed, the infinity signal generating circuit 21 generates an H level signal which is reversed to an L level signal by the inverter 29. Therefore, the AND circuit 28, when receiving an H level signal representative of high brightness from the controller 17, acts so as not to actuate the strobe trigger circuit 30. Thus, when photographing a subject at infinity, a flash exposure is prevented regardless of the brightness of the subject. This prevention of flash exposure by the pushbutton is effectively realized not only in automatic strobes of the type which flash depending on the brightness of the subject but also in strobes of the type which always flash independently of the brightness of the subject. Therefore, a flash exposure which is of no use for subjects at infinity is automatically avoided. In the case of an objective lens having an initial lens position to which the objective lens is always returned after every exposure at the infinity lens position S6, no movement of the objective lens takes place when photographing a remote subject at infinity while pushing the pushbutton 8. In this case, a full depression of the shutter release button 5 is allowed by pushing the pushbutton 8. It may be desirable to provide a pre-setting button which is operated before a half depression of the shutter release button, in place of the pushbutton which is operated simultaneously with the shutter release button. It may also be desirable to detect whether the pushbutton has been operated or not in the distance measurement operation. In this case, the controller could produce a pseudo-infinity signal. Although the present invention has been fully described by way of a preferred embodiment thereof with reference to the accompanying drawings, it is to be understood that other variations and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the true scope of the present invention, they should be construed as included therein.	An automatic focusing camera is equipped with an automatic subject distance detecting device for detecting which of a plurality of predetermined distances is nearest to that at which the subject lies. A lens positioning member adjusts an objective lens to a suitable focusing position in which the objective lens has a depth of field straddling that nearest predetermined distance detected by the automatic subject distance detecting device. Another lens positioning member adjusts the objective lens to a focusing position in which the objective lens will be focused on a subject, such as a landscape, at infinity, independently of the distances detected by the automatic subject distance detecting device. The latter objective lens positioning member is externally operable when it is intended to photograph a subject at infinity, before depressing the shutter button.	6
The invention herein described relates generally to systems and methods for thermally treating solid, granular and aggregate materials and, more particularly, to a system and method for reclaiming spent chemically bonded and/or clay bonded foundry sands. Because the invention was conceived and developed for thermal reclamation of spent foundry sands containing organic or clay binders, and is particularly useful for such, it will be described herein chiefly in this context. However, the invention in its broader aspects could be adapted to thermal treatment of a variety of solid, granular and aggregate materials including, for example, thermal remediation of soils containing organic contaminates, calcining in general, ore roasting, etc. BACKGROUND Various prior art attempts have been made to treat material by thermal reclamation and, in particular, foundry sand. The advantages of reclaiming foundry sand are well known. One advantage is the reduction in the need for virgin foundry sand. In addition, the ability to reclaim used foundry sand obviates the problem associated with the need to find a suitable disposal site for the used foundry sand. A need exists for a foundry sand reclamation system and method that overcome drawbacks and limitations or prior art foundry sand reclamation systems and methods. Principally, there is a need for such a system and method that provides high production output at low cost with high reliability and efficiency. SUMMARY OF THE INVENTION The present invention provides a thermal treatment system and method which satisfies the aforesaid need and which may have more general application in the thermal treatment of solid, granular and aggregate materials. Briefly, the system and method are characterized by a base; an outer drum mounted on the base for rotation about a rotational axis and having an inlet end, a heater end and an annular wall extending between the inlet and heater ends; an inner drum mounted coaxially within the outer drum closer to the heater end than the inlet end of the outer drum, the inner drum having an inlet end, a heater end and an annular wall extending between the inlet and heater ends, the annular wall being spaced radially inwardly from the annular wall of the outer drum to form an annular flow passage surrounding the inner drum, the annular flow passage surrounding the inner drum having an inlet end and an outlet end; passage means at the heater end of the inner drum for allowing material to drop from the inner drum into the outer drum for flow through the annular flow passage from its inlet end to its outer end; means for rotating the outer and inner drums with respect to the base; material conveying means for conveying material from the inlet end of the outer drum to the inner drum for deposit within the interior of the inner drum at its inlet end, the material conveying means including a feed tube through which the material is fed, the feed tube being mounted coaxially within the outer drum and extending from the inlet end of the outer drum to the inlet end of the inner drum, the feed tube being spaced radially inwardly from the annular wall of the outer drum to form an annular flow passage surrounding the feed tube, the annular flow passage surrounding the feed tube having an inlet end connected to the outlet end of the annular passage surrounding the inner drum, an outlet end, and a cross-sectional area greater than the cross-sectional area of the annular passage surrounding the inner drum; means for generating and feeding hot gases into the inner drum for contacting with material fed into the inner drum by the material conveying means thereby to thermally treat the material, the hot gases flowing through the inner drum, then through the annular passage surrounding the inner drum and then through the annular passage surrounding the feed tube; and outlet means for exhausting the hot gases and discharging thermally treated material from the outlet end of the annular passage surrounding the feed tube. According to a preferred embodiment of the invention, the material conveying means includes a feed screw extending through the feed tube substantially along the length of the feed tube, and the feed screw and feed tube are coupled for rotation with the outer and inner drums. The system also preferably comprises a hopper having a discharge chamber at its bottom end located at an inlet end of the feed tube, and the feed screw extends into the discharge chamber for capturing material for transport along the feed tube to the inner drum. Preferably, the feed screw has a first section axially coextensive with the discharge chamber and a second section axially coextensive with the feed screw. the second section has a fixed pitch length and an outer diameter substantially the same as the inner diameter of the feed tube which preferably is of circular cross-section, and the first section has a pitch length less than the pitch length of the second section and an outer diameter less than the outer diameter of the second section. Also preferably, the inner drum has at its inlet end an inlet end wall having a center opening, and the feed tube extends through and has a fit within the center opening that permits at least limited relative axial movement. Further in accordance with a preferred embodiment of the invention, the means for generating and feeding hot gases into the inner drum includes a hot gas tube extending coaxially into the inner drum from the heater end of the drum for directing the hot gases into the inner drum. The hot gas tube preferably extends at least halfway into the inner drum. According to another aspect of the invention, the feed tube is coupled for rotation with the outer and inner drums and has attached thereto a plurality of circumferentially and axially spaced apart, radially outwardly extending flights or blades having material engaging surfaces for contacting the material flowing through the annular passage surrounding the feed tube as the flights rotate around the axis of the feed tube. The blades have material engaging surfaces thereof sloped relative to a plane perpendicular to the axis of the feed tube. The blades and feed tube function to extract heat from the hot gases and material flowing through the annular passage surrounding the feed tube and transfer it to material being fed through the feed tube to the inner drum. A plurality of blades also are provided on the inner drum both interiorly and exteriorly, although in the former instance the blades extend radially inwardly for contacting the material flowing through the inner drum as the blades rotate around the axis of the inner drum. Some of the blades function as paddles having material engaging surfaces oriented parallel to the axis of the feed tube whereas others function as vanes having material engaging surfaces sloped relative to a plane perpendicular to the axis of the inner drum. The paddles and/or vanes preferably have at their radially outer ends lips projecting forwardly of the material engaging surfaces for capturing material as the paddles and/or vanes rotate. The paddles and vanes preferably are circumferentially spaced apart in respective circumferential rows axially spaced apart along the axis of the feed tube, and more preferably at least one circumferential row of paddles is axially disposed between relatively adjacent rows of vanes with the vanes sloped to retard flow of material through the annular space surrounding the feed tube during rotation of the outer and inner drums. A preferred embodiment of the invention also is characterized by the outlet means including a plurality of circumferentially spaced apart outlet openings in an outlet section of the outer drum, and an exhaust hood surrounding the outlet section and within which the outlet section relatively rotates. The exhaust hood includes a gas discharge port and a bottom material discharge port. Provision also is made for transfer of waste heat from hot gases exiting the outlet means to air being supplied to the heater means which preferably is a gas burner which produces hot gases in the heater tube. The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B (together herein referred to as FIG. 1) are broken continuations of a cross-sectional view of a thermal treatment system according to the invention. FIG. 2 is a cross-sectional view showing the interior of the inner drum of the system. FIG. 3 is a cross-sectional view of the inner drum taken substantially along the line 3--3 of FIG. 2. FIG. 4 is a cross-sectional view of the inner drum taken substantially along the line 4--4 of FIG. 2. FIG. 5 is an end elevational view of the system taken from the line 5--5 of FIG. 1B. FIG. 6 is a plan view of a representative blade used in the system. FIG. 7 is an edge view of the blade of FIG. 6. FIG. 8 is a fragmentary cross-sectional view taken along the line 8--8 of FIG. 1A. FIG. 9 is a cross-sectional view of the material conveyor used in the system. FIG. 10 is a cross-sectional view taken along the line 10--10 of FIG. 9. FIG. 11 is a cross-sectional view taken along the line 11--11 of FIG. 9. FIG. 12 is a thermal sand reclamation process flow diagram according to the invention. DETAILED DESCRIPTION Referring now in detail to the drawings and initially to FIG. 1, a system constructed in accordance with the invention is designated generally by reference numeral 10. The system 10 is primarily designed to be utilized for purposes of effecting thermal reclamation of used foundry sand of the kind which contains organic matter or other material that may be broken down through thermal treatment thereby to render the foundry sand reusable. The system 10, herein also referred to as the thermal treatment or reclamation system, comprises an outer containment vessel or drum 12. In the illustrated preferred embodiment, the outer drum is fabricated from a pair of axially juxtaposed cylinders 13 and 14 preferably of the same diameter. At their axially juxtaposed ends, the cylinders 13 and 14 have respective flanges 15 and 16 that are joined together by circumferentially spaced apart bolts (not shown) and corresponding nuts (not shown), or other suitable fasteners that preferably are removable to permit disassembly of the drum 12 for maintenance and/or repair purposes. For heat retention purposes, each cylinder 13, 14 has wrapped therearound one or more layers of insulation material 17, 18 which may be suitably anchored by conventional means to the cylinders and surrounded by an outer protective skin 19, 20. The cylinders 13 and 14 have at their outer ends flanges 23 and 24. The flanges 23 and 24 are mounted to riding rings 25 and 26 respectively. The riding rings are supported in cradle-like fashion by respective pairs 27 and 28 of transversely spaced apart rollers as is further illustrated in FIG. 5. In this manner the outer drum is supported for rotation about its longitudinal axis 29. One pair 27 of the rollers is grooved to receive an annular rib 30 on the corresponding riding ring 25 to prevent axial shifting of the outer drum at one end thereof, herein termed the heater end. The rollers of the other pair 28 and corresponding riding ring 26 are otherwise configured to accommodate limited axial shifting of the opposite end of the outer drum, herein termed the feed or inlet end, to accommodate thermal expansion and contraction of the outer drum relative to the fixed axial spacing between the two sets of rollers. The rollers may be mounted to a suitable base or framework structure schematically indicated at 31 in FIG. 5 to which the various other components of the system may directly or indirectly mounted to provide an overall system unit. The outer drum 12 is rotated by an electric motor 32, although other suitable drive means may be employed as well. The motor 32 is coupled through a speed reducer 33 to a drive sprocket 34 by a drive chain. The drive sprocket 34 is bolted to a heater drum end assembly 35 which in turn is removably attached to the heater end flange 23 by suitable fasteners such as bolts (not shown) and corresponding nuts (not shown). In a manner described in further detail below, the heater drum end assembly 35 has fixedly mounted thereto the heater end of an inner drum 38. Accordingly, the inner drum will be rotated along with the outer drum. As shown, the inner drum preferably is concentric with the outer drum and is housed within the left hand cylinder 13 of the outer drum, as viewed in FIG. 1A. At its opposite or inlet end, to the right in FIGS. 1A and 2, the inner drum 38 is closed by an end wall 39. The end wall 39 has a center opening into which the end of a center feed tube 40 is slip fitted. The feed tube, as well as the opening in the end wall 39, preferably is circular in cross-section and has a diameter considerably less than the diameter of the inner drum. In this manner, the inner drum 38 supports the outlet end of the feed tube 40 which, as shown at the right in FIG. 1B, is fixedly mounted near its inlet end an end outlet section flange 41 at the expansion end of the outer drum in the hereinafter described manner. The slip fit provided between the inner drum end wall 39 and the outlet end of the feed tube 40 accommodates relative thermal expansion and contraction of the inner drum and feed tube as may occur during heat up and cool down of the system. The outlet end of the feed tube may be tapered as shown in FIG. 2 to facilitate insertion of the feed tube into the opening in the end wall of the inner drum during assembly of the system. The feed tube 40 functions as the outer housing of a screw conveyor 42. The screw conveyor 42 further includes a ribbon screw 43 which is fixedly attached to the feed tube for rotation therewith during rotation of the outer and inner drums. That is, the screw, feed tube, inner drum and outer drum together rotate as a unit. At its inlet end, the feed tube 40 extends into an outlet port 46 of a discharge chamber 47 at the bottom of a hopper 48 which is used to hold a supply of unreclaimed sand or other material to be thermally treated. The feed tube is free to rotate in the outlet port and preferably a close fit or suitable seal is provided to prevent sand from escaping through any gap between the tube and surrounding structure of the outlet port. As seen at the right in FIG. 1B, the screw extends beyond the end of the feed tube 40 and into the bottom discharge chamber 47 of the hopper 48 which has a semicircular bottom wall concentric with the longitudinal axis of the screw as further illustrated in FIG. 5. As is preferred, the section 50 of the screw 43 axially coextensive with the feed tube is of uniform pitch and has a diameter closely corresponding to the inner diameter of the feed tube. The screw also has a smaller radius double pitched section 51 which protrudes from the end of the feed tube into the bottom discharge chamber 47. This latter section 51 functions to slowly pull the sand into the feed tube thereby to avoid excessive pressure from being generated in the feed tube. The feed screw 43 supports internally thereof an axially extending temperature probe 55 which protrudes beyond the end of the feed tube and into the interior of the inner drum 38. At its terminal end there is provided a thermocouple 56 (FIG. 1A) or other suitable sensing device for sensing the temperature of hot gases at a point proximate the feed end of the inner drum and coaxially aligned with the heater tube 57 (FIG. 2) of a gas heater assembly 58. The thermocouple leads extend from the thermocouple through a relatively small diameter tube 59 which is attached by attachment lugs 60 to the inner edges of the screw flights at axially spaced apart locations along the length of the screw. The tube 58 protrudes axially beyond the feed end of the feed screw and out through an end wall of the bottom hopper discharge chamber 47, wherefrom the thermocouple leads may be appropriately routed to a system control unit for use in monitoring and controlling system operation. The heater tube 57 protrudes from the heater end of the outer drum 12 and has coupled thereto a gas burner 63 of any suitable type, but it will be appreciated that other types of heating devices may be employed although presently a natural gas burner is generally the most economical. Conventional means are provided for controlling the supply of air to the burner so as to maintain an oxidizing atmosphere and minimum free oxygen in the hot gases generated thereby for maximum thermal efficiency. The hot gases from the burner flow through the heater tube 57 and into the interior of the inner drum 38. The heater tube preferably projects into the drum more than halfway so as to direct the hot gases to the inlet end of the inner drum thereby to maximize the time of exposure of sand to the high temperature gases exiting from the heater tube. The heater tube also provides heat transfer by radiating energy to the sand at a high rate to heat the sand quickly. Typical process temperatures will range from 800° F. (425° C.) to 1500° F. (815° C.) depending on system requirements. As shown in FIG. 2, the inner drum 38 has attached to the interior wall surface thereof a plurality of flights or blades which extend radially inwardly from the drum wall for engaging material fed into the inner drum by the screw conveyor 42. In the illustrated embodiment there are two different types of blades herein designated paddles 66 and vanes 67. The paddles 66 and vanes 67 are essentially the same except that the paddles 66 have generally planar material engaging surfaces oriented perpendicular to the axis of the inner drum. On the other hand, the vanes 67 have generally planar material engaging surfaces sloped in relation to a plane perpendicular to the axis of said inner drum. As shown, the paddles and vanes are arranged in respective circumferential rows that are axially spaced apart along the inner drum. The circumferential arrangement of the blades is illustrated further in FIGS. 3 and 4. As further shown in FIG. 4, the inlet end of the inner drum is supported by radially extending ears 68 on struts 70 extending radially inwardly from the outer drum. The ears 68 rest on the struts so that the inner drum may be easily axially withdrawn from the outer drum upon detachment of the end wall assembly 35 from the outer drum flange 23. The paddles and vanes 66 and 67 preferably extend radially inwardly to a point just short of contacting the heater tube 57. At their radially inner ends, the paddles and vanes preferably are each provided with a lip 69 which functions, during rotation of the inner drum, to capture and lift sand as the blade rotates upwardly. As the blades rotate upwardly after passing through sand in the bottom of the inner drum, the sand will fall back away from the lips and cascade down through the gas stream. This lifting function is primarily performed by the paddles whereas the vanes primarily function, because of their orientation, to retard flow of material through the inner drum to increase the residence time of the material flowing in the inner drum from right to left in FIG. 1. In FIGS. 6 and 7, a representative blade is designated generally by reference numeral 71. The blade 71 is representative of both the paddles 66 and vanes 67, which primarily differ by reason of their orientation relative to the axis of the inner drum as above described. As shown, the blade 71 has a material engaging surface 72 and a forwardly protruding lip 73 at its radially outer end. The radially inner edge 74 of the blade is suitably configured for welding to the surface of the inner drum 38. For the paddles 66 a straight radially inner edge is sufficient. For the vanes, however, it is preferable to provide a slightly convex radially inner edge 74 to better match the radius of the inner wall surface of the inner drum 38. As is discussed further below, the same type of blade is attached to the outer diameter wall surface of the inner drum, in which case the radially inner edge of the blade may be slightly convex to facilitate welding of the blade to the drum. Also, similar but radially longer blades are attached as by welding to the outer diameter surface of the feed tube 40, in which case the radially inner edge of the vanes can again be slightly concave to facilitate welding whereas again the radially inner edge of the paddles may be straight. At the heater end of the inner drum 38, as shown at the left in FIG. 2, there is provided an annular outlet passage 76 for allowing material to drop from the inner drum 38 into the outer drum 12 for counterflow through an annular flow passage 77 formed between the larger diameter inner surface of the outer drum and the smaller diameter outer surface of the inner drum. In the illustrated preferred embodiment, the annular outlet passage is formed between the heater end of the inner drum and an end wall 78 closing the heater end of the outer drum. The inner drum is mounted to the end wall by a circumferential arrangement of brackets 79 which hold the inner drum axially spaced away from the end wall to form the annular outlet passage 76. As shown in FIG. 1A, the inner drum 38 has attached to the exterior wall surface thereof a plurality of flights or blades 82 and 83 which extend radially outwardly from the drum wall for engaging material flowing through the annular flow passage surrounding the inner drum. Again there preferably are two different types of blades herein designated paddles 82 and vanes 83 that are similar in shape and function to the paddles and vanes 66 and 67 within the inner drum. The paddles 82 have generally planar material engaging surfaces oriented perpendicular to the axis of the inner drum. On the other hand, the vanes 83 have the generally planar material engaging surfaces sloped in relation to a plane perpendicular to the axis of the inner drum. As shown, the paddles and vanes are arranged in respective circumferential rows that are axially spaced apart along the inner drum. The blades preferably extend radially outwardly to a point just short of contacting inner diameter wall surface of the outer drum 12. At their radially outer ends, the blades and especially the paddles preferably are provided with lips which function during rotation of the inner drum to capture and lift sand as the blades rotate upwardly after passage through material in the lower region of the annular passage 77. As the paddle continues to rotate upwardly the sand will fall back away from the lips and cascade down over the inner drum. Because of their orientation, the vanes function to retard flow of sand moving through the annular passage 77 surrounding the inner drum from left to right in FIG. 1A. As shown in FIG. 1B, the feed tube 40 has attached to the exterior wall surface thereof a plurality of flights or blades 86. The blades 86 extend radially outwardly from the tube wall for engaging material flowing through an annular flow passage 87 formed between the feed tube and outer drum 12. Because the feed tube is substantially smaller in diameter than the inner drum 38, the annular flow passage 87 has a cross-sectional area considerably larger than the cross-sectional area of the annular flow passage 77 surrounding the inner drum 38. Consequently, the blades 86, which extend radially outwardly from the feed tube to a point closely adjacent the interior wall surface of the outer drum 12, have substantially greater surface area exposed to hot gases passing through the annular chamber 87 than the blades 82 and 83. This promotes efficient extraction of heat from the hot gases passing through the annular chamber 87 for conduction along the blades 86 to the inner tube for preheating the sand being fed through the inner tube. Also, the blades 86 extract heat from sand flowing through the annular chamber 87 when they engage the sand. As shown, the blades 86 preferably are sloped in relation to a plane perpendicular to the axis of the outer drum 12 and are oriented such that they function to retard flow of the sand through the annular passage 87. Blade 86 also retards flow of gas through annular passage 87 which increases gas flow turbulence and this aids in achieving complete combustion of organic compounds in the gas. Hence, the blades may be designated herein as vanes which are configured similar to the blade shown in FIGS. 6 and 7, although of relatively longer radial length. As viewed in FIG. 1B, sand flows through the annular passage 87 from left to right. As heat is extracted from the hot gases and sand passing through the flow passage 87, the hot gases and sand is correspondingly cooled. The hot gases and sand flow from the annular passage 87 into an outlet section of the outer drum indicated generally at 90 in FIG. 1B. The outlet section 90 has a flange 91 mounted by suitable fasteners to the flange 24 on the outer drum cylinder 14 and at its opposite end the flange 41 to which a flange 92 of an end wall assembly 93 is mounted by suitable fasteners. The outlet section 90 includes a plurality of circumferentially spaced apart outlet ports 96. The portion of the outlet section 90 containing the outlet ports 96 is surrounded by a hood 97 which also is illustrated in FIG. 5 as well as in FIG. 1B. The hood 97 has a bottom discharge outlet 98 through which the thermally processed sand exits the system. The hood 97 also has at its upper end a gas discharge outlet 99 through which the hot gases are exhausted. The exhaust gases preferably are passed through an indirect heat exchanger 102 for heating supply air that is directed via duct 103 to the gas burner 63. In this manner the supply air is preheated and the exhaust gases are further cooled prior to passage to the atmosphere preferably via a bag house which includes a draft fan for creating negative pressure in the interior of the system 10. Referring now to FIG. 8, the manner in which the riding ring 25 is mounted to the outer drum 12 is illustrated, such illustration and the following description being equally applicable to the riding ring 26. The riding ring 25 is mounted to the outer drum by a plurality of circumferentially spaced apart pivoting strut assemblies, a representative one of which is designated generally by reference numeral 105 in FIG. 8. In the region of the outer drum 12 that is circumscribed by the riding ring 25 there is attached as by welding to the adjacent flange 23 an outer mounting ring 106. Each pivoting strut assembly 105 has an L-shape strut 107 having a short leg attached as by welding to the outer ring 106 at a point reinforced by radial rib plates 108. The long leg of the strut 107 is pivotally attached at its distal end by a pin 109 to a lug 110 attached as by welding to the interior surface of the riding ring 25. With this arrangement, the strut assemblies 105 mount the riding ring 25 to the outer drum 12 while permitting thermal expansion and contraction of the outer drum 12 relative to the riding ring 25 as may occur during heat up and cool down of the system. Referring now to FIGS. 9-11, the material conveyor 42 is further illustrated. The conveyor assembly 42 includes the end plate 92 which is attached to the feed tube 40 and reinforced by triangular gussets 114. On the outer side of the end plate 92 there is provided one or more layers of insulation 115. Similarly, one or more layers of insulation 116 is provided on the outer side of the end wall 78 closing the opposite end of the outer drum 12 as seen at the left in FIG. 2. The insulations 115 and 116 provided at the end of the outer drum and the insulations 17 and 18 surrounding the outer drum function as an insulating jacket for minimizing the escape of heat from the system to the atmosphere. The end wall 92 is preferably removably attached by suitable fasteners to the flange 41. As further seen in FIG. 9 and with additional reference to FIGS. 10 and 11, the last two turns of the feed screw 43 have associated therewith semi-circular flow retarding plates 118 and 119. The plates 118 and 119 are provided to increase the residence time of the material being fed through the feed tube particularly in the area surrounded by the annular chamber 87 thereby to enhance the preheating of the incoming sand. Preferably, the feed screw 43 is slightly smaller in diameter than the inner diameter of the feed tube 40 so that the feed screw can be inserted axially into the feed tube. The feed screw may then be tack welded at its accessible inlet end to the feed tube so that it will rotate with the feed tube during the rotation of the inner and outer drums. In the event there is a need to remove the feed screw from the feed tuve such as for repair purposes, the accessible welds may be broken and the feed screw removed from the feed tube. It also is noted that the conveyor assembly 42 may be easily removed from the outer drum by demounting the end wall 92 from the flange 41, followed by axially withdrawal of the conveyor assembly from within the outer drum 12. The operation and methodology of the invention will now be described chiefly with reference to FIG. 12 which is a process flow diagram. In operation, the outer drum is rotated as are the inner drum, feed tube and feed screw with the outer drum. During such rotation, spent foundry sand will be fed from the hopper 48 through the feed tube 40 and into the inner drum 38. The sand exiting the feed tube will fall on to the bottom of the inner drum where it will build up and be engaged initially by the first circumferential rows of paddles 66 (FIG. 2). As the inner drum turns the paddles lift the sand upwardly. As the paddles continue to rotate upwardly the sand will fall off and flow downwardly through the hot gases being injected towards the inlet end of the inner drum by the heater tube 57. As sand builds up at the inlet end of the inner drum it will tend to flow to the left in FIG. 12 and progressively into engagement with the following circumferential rows of vanes and paddles. The vanes function to retard the flow while the paddles primarily function to lift the sand and allow it to flow downwardly through the hot gases in the inner drum. As illustrated in FIG. 2, there are two adjacent rows of paddles located axially adjacent the outlet end of the heater tube 57 thereby to maximize the contact of the sand with the hot gases entering the inner drum. This heating and mixing action will operate to calcine the sand thereby to rid the sand of organic binders and the like. As sand continues to be fed into the inner drum, sand will flow from right to left in FIG. 12 as it continues to be subjected to the agitation action of the paddles and vanes. When the sand is axially coextensive with the heater tube 57, the sand falling from the paddles will cascade over the heater tube which will be at a relatively high temperature in view of the hot gases being passed therethrough. As the hot gases exit the burner tube, they will reverse direction in the inlet end of the heater drum and flow from right to left in FIG. 12 further making contact with the sand that also is moving from right to left in FIG. 12. As the sand reaches the heater end of the inner drum it will drop through the annular outlet passage 76 for counterflow through the annular flow passage 77. As the sand moves through the annular flow passage 77 it will lift the sand up and it cascade it down over the inner drum to continue uniform heating of the sand and burn off of carbonaceous material. Also, the vanes moving through the annular flow passage 77 will operate to further agitate the sand and retard its flow to increase the residence time of the sand in the high temperature region of the system. The hot gases also will flow out of the inner drum through the annular outlet passage 76 and then through the annular flow passage 77. The hot gases then flow into the annular flow passage 87 where the hot gases come into contact with the blades attached to the feed tube 40. The blades, being at an angle, require the exhaust gases to work their way around them and thereby generates turbulence within the annular flow passage 87 to ensure complete combustion. The blades also function to extract heat from the exhaust gases which heat is conducted to the feed tube 40 for preheating the incoming sand being fed through the feed tube 40. The blades also function to retard flow of sand through the annular flow passage 87 and to extract heat flowing through the annular flow passage 87 from left to right in FIG. 12. After traversing the annular flow passage 87 the sand moves to the outlet section where it exits through the then downwardly disposed outlet port for discharge to a bottom outlet of the hood 97. The exhaust gases will also move into the outlet section and exit through the outlet port for passage through the heat exchanger 102 for preheating air supplied to the gas burner 63 (FIG. 1). The exhaust gases may then be exhausted to the atmosphere preferably via a bag house for removing any particulate material that may be entrained in the exhaust gas. By way of specific example, the outer drum may have an overall length of about 19 feet and a diameter of about five feet. More particularly, each cylindrical section of the outer drum may have a length of about 90 inches and the outlet section may have a length of about 36 inches. The inner drum may have a diameter of about 40 inches and a length of about 80 inches. As for the feed tube, it may have a diameter of about 17 inches and a length of about 176 inches. A system having components of the aforedescribed size may be operated at a drum rotation speed of from two to four revolutions per minutes. Also, the gas burner may be operated to generate hot gases at a temperature preferably ranging from 800° to 1500° F. For recycling spent foundry sand, preferably the hot gases are entering the inner drum at a temperature of at least 1300° F. to ensure complete combustion of volatile organic compounds contained in the spent foundry sand. The sand may have an overall residence time of about 55 minutes of which about 20-25 minutes is in the inner drum and the rest is in the outer drum or being fed through the feed tube. The various components of the system may be made of any suitable material. For example, the major components may be fabricated from an alloyed carbon steel such as, for example, ASTM 387, grade 11 material which is suitable for use in gas fired equipment. Also, the outer drum may be jacketed with about six inches thick insulation. Although the invention has been shown and described with respect to a preferred embodiment, it is obvious that equivalent alternations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the following claims.	A thermal treatment system and method characterized by an outer drum mounted on the base for rotation about a rotational axis; an inner drum mounted coaxially within the outer drum closer to a heater end thereof than an inlet end of the outer drum, the inner and outer drums forming therebetween an annular flow passage surrounding the inner drum; a passage at a heater end of the inner drum for allowing material to drop from the inner drum into the outer drum for flow through the annular flow passage from its inlet end to its outer end; material conveying structure for conveying material within a feed tube from the inlet end of the outer drum to the inner drum for deposit within the interior of the inner drum at its inlet end, the feed tube being mounted coaxially within the outer drum and being spaced radially inwardly from the annular wall of the outer drum to form an annular flow passage surrounding the feed tube that has an inlet end connected to the outlet end of the annular passage surrounding the inner drum and a cross-sectional area greater than the cross-sectional area of the annular passage surrounding the inner drum; a burner for generating and feeding hot gases into the inner drum for contacting with material fed into the inner drum by the material conveying structure thereby to thermally treat the material, the hot gases flowing through the inner drum, then through the annular passage surrounding the inner drum and then through the annular passage surrounding the feed tube; and an outlet for exhausting the hot gases and discharging thermally treated material from the outlet end of the annular passage surrounding the feed tube.	1
TECHNICAL FIELD The present invention relates generally to rotary electric machines, for motor operation as well as for generator operation, and specifically relates to a method of optimizing the performance utilization of electric machines, a rotary electric machine, a use of such a machine and a rotor for such a rotary electric machine. BACKGROUND The development within this area is presently directed towards an ever higher output in terms of power and torque, for given machine sizes. This means that manufacturers of such machines are pressed, primarily by the current tough price competition, to increase the performance of the machines so that smaller machines that are less expensive to manufacture may be employed for a given range of power output. In conventionally designed machines such a development towards electric machines having higher and higher performance utilization, that is an increased output of power and torque, has led to increased dimensions for the rotor winding conductors and to the coherent increased dimensions for the rotor winding grooves, especially with reference to the radial depth of the grooves. To a great extent this depends upon the fact that in such machines it has not been possible to obtain a cooling that is so efficient that the size of the rotor winding grooves can be kept down. To exemplify this it can be mentioned that in direct current machines the conventional cooling is based on axial cooling channels 5 , 6 provided in accordance with a standardized hole configuration in the rotor 1 , i.a. such as it is illustrated in the enclosed FIG. 1 . In the normal case the same hole configuration is employed for all of the different numbers of winding grooves 4 used for a given rotor diameter in a particular series of motors. Thereby the number of cooling holes or channels being positioned at the same radial distance from the centre C of the shaft is normally an integer multiple of the pole number of the machine, in order to provide a relatively constant summated flow in the magnetic circuit through the rotor, irrespective of the polar position of the rotor. Expressed in an other way, the number of outer cooling channels as well as the number of inner cooling channels are each an integer multiple of the pole number. Since the number of winding grooves varies and is normally not divisible with the pole number, the distances between the rotor winding grooves and the rotor cooling channels will not be the same anywhere around the circumference of the rotor. This in turn leads to the fact that the magnetic circuit will have an unequal flow distribution at the respective winding grooves around the circumference of the rotor. In order to minimize the negative effects thereof upon the electrical properties of the machine, the distance between the winding grooves and the cooling channels must be designed relatively large, with the accompanying poor cooling and greatly limited power and torque output. In order to increase the power and torque output from such a direct current machine having a conventional cooling hole configuration in the rotor, in accordance with the above, the rotor conductor area and thereby the dimensions of the winding grooves must be increased, as stated above. Simultaneously the distances between the winding grooves and the cooling channels must be made smaller. However, due to the above described unequal flow distribution, said measures impair the electric properties of the machine, which in particular results in a considerably decreased commutation capacity at high power outputs. Thereby, it is not unusual for rotary electric direct current machines having a conventional cooling, to be impaired by such substantially increased electrical strain or stress that the contact function between the brush and commutator reaches an upper limit. In the absence of any margin for this contact function, the direct current motor becomes very sensitive to external disturbance. To sum up, it may therefore be established that the conventional design in itself has performed well, with the above discussed limitations. However, it is based on the unfortunate compromise between on the one hand a desire to achieve an efficient cooling and, on the other hand the aim towards providing a machine having good electrical properties. SUMMARY OF THE INVENTION In the light of the above discussion, a basic object of the invention is to provide a simple method of combining high performance in a rotary electric machine with an improvement of the electrical properties thereof. Expressed otherwise, the aim is to eliminate the need to compromise between efficient cooling and good electrical properties. To be precise, this object is obtained specifically for a direct current machine by providing wide black bands, that is low commutation strain for the electric machine in order to thereby obtain a functionally stable operation with low maintenance. The invention is based on the understanding that the need for said compromise can be eliminated and that, instead, the cooling and the electrical properties can both be optimized simultaneously by creating symmetry in the magnetic circuit of the motor. According to the invention this is achieved by providing at least the mainly effective, outer axial cooling channels in the rotor of the machine essentially symmetrically with reference to the magnetic flow paths in the rotor. Thereby a symmetrical design of the magnetic circuit of the machine is obtained, whereby a good electromechanical motor function is obtained with, for a direct current machine, low maintenance of brushes and commutator. Simultaneously wide shunt regions can be obtained without reduction of the rated output. In one embodiment of the invention the symmetrical design of the magnetic circuit, according to the basic object of the invention, is combined with the provision of a great number of outer cooling channels in the rotor, positioned near the rotor winding grooves, that is at a large radial distance from the centre of the rotor shaft. By combining the symmetry of the magnetic circuit and the large number of outer cooling channels a very good possibility is provided for improving the performance utilization of a rotary electric machine. In particular this improvement is achieved by the fact that the good electrical properties provided in accordance with the basic object of the invention can be maintained and even improved further by means of the increased cooling capacity that in turn permits the reduction of the size of the winding grooves. Through the symmetrical positioning of the cooling channels they can be provided in a large number and at the same time they can be moved up close to the winding grooves and thereby close to the source of the power loss in the form of resistive loss in rotor conductors in rotor winding grooves and magnetic or iron loss in rotor groove teeth. In accordance with further preferred embodiments of the invention the outer cooling channels are provided in a number corresponding to half of the number of rotor winding grooves when the latter is even, or alternatively in a number that is an integer multiple of the number of rotor winding grooves. In accordance with a further embodiment the cooling channels are provided with an enlarged inner peripheral surface and/or cross section area. This is obtained partly by the positioning of the cooling channels further out from the centre of the shaft of the machine, which allows for cooling channels having a larger cross section area, and partly by giving the cooling channels an elongated form, as seen in the radial direction, and/or forming them with a profiled, for instance polygonal or wavy surface. Hereby a further improved cooling capacity is obtained, which permits raising the current density in the rotor winding. This in turn contributes further to the reduction of the dimensions of the rotor winding grooves. For a direct current machine this means that the commutation strain can be reduced. Other advantages that are obtained by means of the invention are that the temperature gradient radially through the rotor plate can be reduced. This means that, compared to plates having a conventional cooling configuration, larger rotor plates can be cold-pressed on the rotor shaft since the shaft hole of the rotor plate does not expand so much in the operating temperature condition, that the grip between the shaft and the rotor plate is lost. In these embodiments the cooling surfaces are increased and provided closer to the heat source/power loss source, which means that temperature peaks in the winding grooves can be reduced at temporary overloads. According to another aspect of the invention a rotor for a rotary electric machine is provided, which employs the principles of the present invention. A further aspect of the invention relates to the use of a rotary electric machine designed in accordance with the basic principles of the invention, for motor operation. Further objects, features and advantages of the invention are indicated in the dependent claims and in the following description of exemplifying embodiments thereof. BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which: FIG. 1 very schematically illustrates a partial plan view of a rotor plate of a rotary electric machine, said rotor plate being provided with a cooling hole configuration in accordance with the prior art, FIG. 2 in a view corresponding to that of FIG. 1 illustrates a first embodiment of a cooling hole configuration in accordance with the invention, FIG. 3 illustrates an alternative embodiment of the cooling hole configuration according to the invention, FIGS. 4-7 illustrate further variants of the inventive cooling hole configuration, FIG. 8 is a diagram illustrating differences in field weakening area for direct current machines having high and low, respectively, commutation strain, FIG. 9 is a diagram illustrating differences in black bands between conventionally designed direct current motors and a machine according to the invention, FIG. 10 illustrates a further alternative embodiment of the cooling hole configuration according to the present invention, and FIGS. 11 a-c illustrate examples of alternative embodiments of cooling channels. DETAILED DESCRIPTION With reference primarily to FIGS. 1-3 the basic principles of the invention shall now be described with the aid of two embodiments (FIGS. 2-3) of the application thereof to direct current machines. At the same time the differences in comparison with conventionally designed direct current machines (FIG. 1) shall be explained. In all of these figures, as well as in FIGS. 4-7 and 10 the invention is illustrated by means of a very schematically shown radial portion of a rotor plate in a laminated rotor of a direct current machine. It is understood that the rotor plates of a plate stack are provided with the same cooling hole configuration and with the cooling holes aligned with each other for forming axial cooling medium channels. As is stated in the introduction the basic object of the invention is to provide symmetry in the magnetic circuit of the electric machine. In the first embodiment of the present invention (illustrated in FIG. 2) this is achieved by providing those cooling channels 15 of the rotor plate 10 that are mainly active in cooling the machine, symmetrically in relation to the rotor winding grooves 14 . It shall be explained, in this connection, that the cooling channels 15 that are mainly active in the cooling are the outer cooling channels, that is those positioned closest to the rotor winding grooves 14 . In order to achieve the objects of the invention it is therefore essential that in particular the cooling channels 15 that are mainly active in the cooling, are positioned symmetrically. Consequently the invention also covers embodiments where other cooling channels, that are of secondary importance for the cooling, are positioned in a non-symmetrical manner, at a smaller radial distance from the centre C of the rotor shaft 12 and/or are provided with another spacing or pitch than the main cooling channels 15 . For achieving the symmetry provided in accordance with the invention, the cooling channels 15 are, in the embodiment illustrated in FIG. 2, provided in a number corresponding to the number of rotor winding grooves 14 , and thus corresponding to the number of groove teeth 13 . This allows for symmetry, whether the number of rotor winding grooves 14 is odd or even. With the cooling hole configuration designed in accordance with the invention the cooling channels can be provided in a greater number in comparison with the conventional technique, and they can be positioned further outwardly from the centre C of the rotor shaft 12 , which in itself provides space for larger cooling channels. Through the enlarged surface on one hand and by being positioned closer to the source of the power loss, that is the heat source, on the other hand, the cooling channels can therefore provide an essentially improved cooling, without disturbing or impairing the electrical properties. In the embodiment of FIG. 2 the cooling channels 15 are formed having a radially elongated shape for providing a further increased cooling surface. However, said enlargement of the surface can also be obtained in other ways, as is exemplified in FIGS. 11 b and 11 c by means of the polygonal and wavy shapes of the inner surface of the cooling channels illustrated therein. In contrast to the above described embodiment of the present invention, the conventionally punched rotor plate 1 illustrated in FIG. 1 has relatively few outer cooling channels 5 positioned comparatively far from the rotor winding grooves 14 and from the groove teeth 3 lying therebetween. Moreover, an array of inner cooling channels 6 is provided at a smaller radial distance from the centre C of the rotor shaft. The cooling hole configuration illustrated in FIG. 1 is conventional in today's direct current motors which, as mentioned, are normally formed having the same standardized hole configuration for all of the different number of winding grooves used for a given rotor diameter in a certain series of motors. In the normal case, the number of outer cooling holes 5 as well as the number of inner cooling holes 6 are each an integer multiple of the number of poles of the machine. The purpose thereof is to provide a relatively constant summated flow in the magnetic circuit through the rotor, irrespective of the polar position of the rotor. This means that the number of outer cooling channels 5 as well as the number of inner cooling channels are each an integer multiple of the number of poles. In consequence thereof, the distances between the rotor winding grooves 4 and the rotor cooling channels 5 , 6 will not be equal anywhere around the circumference of the rotor. As was mentioned above, in order to avoid an uneven flow distribution in direct current machines having a conventional cooling hole configuration, it must be seen to that the distance between the winding grooves 4 and the cooling channels 5 , 6 is relatively large, with the resulting poor cooling and limited output of power and torque. The improvements in the form of enhanced electrical properties that are achieved by means of the principles of the invention are illustrated more clearly in FIG. 8 and 9. FIG. 8 illustrates a comparison between the performance of a direct current motor designed in accordance with the principles of the present invention (curve A) and a direct current motor produced in accordance with the conventional technique (curve B). FIG. 9 illustrates a comparison between the black bands of a direct current motor designed in accordance with the principles of the present invention (curve A) and of a direct current motor of the conventional design (curve B). Initially it should be stated, with reference to FIG. 8, that generally, high commutation strain greatly restricts the possibility to provide speed control for direct current motors through “field weakening”, and that when a wider field weakening area is required for a direct current motor having high commutation strain, the rated power must be reduced. This means that the motor must have a higher original power rating than a motor having such low commutation strain that its output does not have to be reduced in order to provide for a speed control through field weakening. FIG. 8 specifically indicates the differences in the field weakening area of the conventional motor having high commutation strain according to curve B, compared to a motor according to the invention, having low commutation strain. There are indeed direct current motors available on the market, which have relatively high performance in relation to the size of the motor, but in most cases these motors are characterized by a small shunt area corresponding to FIG. 8 . Only a small number of direct current motors available on the market present field weakening areas like the one of curve A, for the motor according to the invention, but in such cases they usually have significantly lower performance relative to the size of the motor. One the other hand, a distinguishing feature of a direct current motor designed in accordance with the principles of the present invention is that very high rated output and very high torque at rated load may be taken out at the same time as the field weakening area, that is the range of speed with constant power, is wide. For direct current motors with speed control through voltage control or direct current motors operated with a relatively constant speed low commutation strain is also desirable, since this is a basic condition for obtaining a functionally stable operation with low maintenance. With a conventional design and at high performance the result is often small, narrow black bands, that is the result is a small area within which the direct current motor operates sparkless when a certain disturbance in the form of an applied or tapped current (boost, buck, see FIG. 9) is introduced over the commutation circuit. In connection with high performance utilization it may even come to the situation where the black bands nearly disappear. It has been stated above, that curve B in FIG. 9 specifically illustrates typical black bands for such a conventional direct current motor and these should be compared to curve E that shows the black bands required for obtaining a functionally stable operation with low maintenance. The black bands according to curve B are sufficient for obtaining a sparkless operation in a laboratory environment, but a higher level according to curve E is required to avoid sparking or arcing in practical operation where disturbance in the form of current ripple, environmental influence upon the patina, mechanical vibration from the operation etc. are added. Otherwise sparking will occur, causing wear on both brushes and commutator and thereby requiring increased maintenance. On the contrary, stable and wide black bands within the entire operating range are characteristic of rotary electric motors produced in accordance with the principles of the present invention. This is illustrated in curve A, and it is clearly visible that the black bands are definitely better for the motor according to the invention than for the conventional motor. This applies even if only the conventional motor would be provided with a compensating winding in the stator, with the additional cost involved. To sum up, the wide black bands obtained with a rotary electric direct current motor designed in accordance with the principles of the invention provide the following advantages in relation to a typical conventional direct current motor: Eliminated sparking and thereby reduced brush wear, reduced commutator wear and reduced need for cleaning from coal dust caused by brush wear Reduced need for inspection during operation Increased availability through extended intervals between shutdowns for maintenance and service Increased ability to withstand the additional disturbance in the form of black band reduction, that is caused by the current pulsation of the converter, ripple, in both the armature circuit and the field circuit Increased ability to withstand the additional disturbance in the form of black band reduction, that is caused by mechanical vibration Makes it possible to maintain a sparkless operation even in the case where brushes having inferior black bands must be used as a result of current operational conditions. FIG. 3 illustrates an alternative embodiment of the cooling hole configuration according to the invention, whereby the outer cooling channels 25 in this case are provided at the same radial distance from the centre C of the rotor shaft 22 and in a number corresponding to half the number of rotor winding grooves 24 . In this case positioning the cooling channels on a radius passing centrally through every other groove tooth 23 provides the symmetry in relation to the flow paths. FIG. 4-7 illustrate further alternative embodiments of the cooling hole configuration according to the invention, whereby the embodiment according to FIG. 4 corresponds to that of FIG. 2 in the respect that the outer cooling channels 35 are provided in a number corresponding to the number of rotor winding grooves 34 , whether the number of grooves is even or odd. However, the outer cooling channels 35 are displaced in relation thereto, such that they are positioned on a radius from the centre C of the rotor shaft 32 and through the centre of each groove tooth 33 . The embodiment according to FIG. 5 corresponds to that of FIG. 3 in the respect that here too the number of cooling channels 45 corresponds to half the number of rotor winding grooves 44 in the rotor plate 40 . The difference is that the cooling channels 45 are here positioned on a radius from the centre C of the rotor shaft 42 through the centre of every other rotor winding groove 44 . According to the principles of the invention the number of outer cooling channels can be another integer multiple of the number of rotor grooves, for instance three, four, five, six and so forth, times the number of rotor winding grooves, and this is generally illustrated in FIGS. 6 and 7. Said figures illustrate two different embodiments having double the number of cooling channels as the number of rotor winding grooves, but with the cooling channels positioned either in line with each rotor winding groove and in line with each groove tooth (FIG. 6 ), or with one cooling channel provided at each transition from a groove to a groove tooth. In the embodiments of the invention illustrated in FIGS. 2-7 those outer cooling channels 15 of the rotor plate 10 that are mainly active in the cooling, and that are positioned closest to the rotor winding grooves are all provided at the same radial distance from the center of the rotor shaft. However, the invention is not restricted to such a design. In order to illustrate this FIG. 10 shows an embodiment where the cooling channels 85 , 85 ′, which in this example are provided in the same manner as those in FIG. 4 with respect to their number and polar position, are provided displaced in relation to each other in the radial direction of the rotor. Expressed otherwise, they are provided at two different radial distances R 1 and R 2 from the center of the rotor shaft. In this specification these distances are calculated starting from the point on the cooling channel wall being closest to the outer circumference of the rotor plate. It shall be emphasized that the principles of the embodiment in FIG. 10 may as well be applied to designs where the number and polar position of the cooling channels correspond to those according to any of the other embodiments of FIGS. 2, 3 , 5 , 6 or 7 , and/or where they are of another shape than that illustrated in FIGS. 2-7 and for instance correspond to that of FIGS. 11 a-c. Therefore, the embodiment of FIG. 10 generally exemplifies that in accordance with the invention the expressions “outer cooling channels that are mainly active” or “cooling channels closest to the rotor winding grooves” comprise all cooling channels positioned between the two radiuses R 1 and R 2 when these lie in the area R 2 −R 1 ≦8+D·0.03, where R 2 and R 1 denote radiuses from the center C of the shaft in mm and D is the diameter of the rotor plate in mm and where R 2 is always the larger of the two radiuses. Especially in the cases where high demands are made on the cooling of the rotor it is particularly advantageous if all “outer cooling channels that are mainly active” or “cooling channels closest to the rotor winding grooves”, in a variant of the embodiment in FIG. 10, are positioned between the two radiuses R 2 and R 1 when these lie in the narrower area R 1 ≦5∓D·0.02 mm. Another variant of the invention is illustrated in FIG. 11 a , where the separate outer cooling channels of FIG. 2-7 have been replaced by a group of cooling channels 55 of which each may be asymmetrically positioned, but which when looked upon as a group, fall within the basic inventive idea. In this figure is illustrated a group 55 consisting of three channels, but the number can be from two and upwards, with the upper limit being determined by practical restrictions. In the embodiments of FIGS. 2-7 the separate cooling channels have been illustrated having a radially elongated shape, in addition to the surface enlargement obtained by the positioning at a comparatively large radial distance from the center of the rotor shaft. FIG. 11 b and 11 c illustrate alternative embodiments for obtaining this further surface enlargement by providing a polygonal shape, the cooling channel 65 according to FIG. 11 b , or a wavy shape, the cooling channel 75 of FIG. 11 c , for the inner peripheral surface of the outer cooling channels. It is obvious that the invention covers also other shapes than those specifically illustrated. The invention is presently regarded as having its major field of application in connection with a machine intended for motor operation, and for which the aim is high performance and at the same time a minimum of maintenance for brushes and commutator and/or a wide range of speeds. An example thereof is an application in a coiler motor. It shall be obvious though, that the principles of the invention are likewise applicable to a machine for generator operation A further variant, not illustrated in the drawings, that falls within the basic principles of the invention, is a design in which the outer cooling channels are positioned asymmetrically with reference to the rotor winding grooves, adapted to specific applications, for providing or compensating for different electromagnetic properties in different directions of rotation. Furthermore, it shall be emphasized that even if the invention has been explained in the above specification with specific reference to an application of its principles in a direct current machine, it also covers an application in alternating current machines. An example of such a use of the invention is in asynchronous machines, and more specifically, preferably in such machines having a forced cooling. In alternating current machines the inventive principles can be employed for a strictly axial cooling as well as in combination with conventional radial cooling channels. The invention shall therefore also comprise such applications. It will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departure from the scope thereof, which is defined by the appended claims.	The invention relates to a method of improving the performance of a rotary electric machine through improved cooling, whereby a cooling fluid is conducted through axial cooling channels ( 15 ) in the rotor, radially inwardly of the rotor winding grooves ( 14 ), whereby the cooling fluid being mainly active in cooling the machine is conducted through axial cooling channels ( 15 ), or alternatively groups of cooling channels, that are provided essentially symmetrically with reference to the magnetic flow paths in the rotor, for achieving a symmetry in the magnetic circuit and thereby good electrical properties for the machine. The invention is also directed to a rotary electric machine, a rotor therefor and a use thereof.	7
CROSS-REFERENCE TO RELATED APPLICATION This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-58583, filed on Mar. 16, 2011, the entire contents of which are incorporated herein by reference. FIELD The embodiments discussed herein are related to a support program, a support apparatus, and a support method. BACKGROUND Up to now, an apparatus configured to support a circuit design by a user is proposed. For example, at a stage of the circuit design on a printed circuit board, the apparatus in related art stores a changed part and an unchanged part in a storage apparatus while being distinguished from each other. Then, the apparatus in related art performs a physical design on the unchanged part by using already designed data. Also, according to the technology in related art, a circuit such as a printed circuit board is produced through a process including a conceptual design by a designer or the like, the circuit design, the physical design, and a fabrication. Also, the produced circuit may be revised through a carryover design in some cases because of various reasons such as an addition of a function, a component revision, and a reduction in size of a casing that accommodates the circuit. In this case, the designer converts physical design data into conceptual design data and examines a wiring, an arrangement, and the like again from the conceptual design. See Japanese Laid-open Patent Publication No. 3-88071. SUMMARY According to an aspect of the invention, a computer-readable medium storing a support program that causes a computer to execute operations, the operations including reading out, from a memory that stores arrangement information on a component on a circuit and analysis information indicating a result of an analysis on the component, the arrangement information on the component and generating image information, reading out the analysis information that is information related to whether or not an examination is to be carried out with respect to the component from the memory, and changing a display attribute of the component which is included in the image information in accordance with the analysis information. The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 illustrates a configuration of a support apparatus according to a first embodiment; FIG. 2 illustrates an example of respective components on a circuit indicated by arrangement information on the components; FIG. 3 illustrates an example of an analysis information DB; FIG. 4 illustrates an example of a result of a signal analysis; FIG. 5 illustrates an example of revised edition information; FIG. 6 illustrates an example of the revised edition information; FIG. 7 illustrates an example of an image before and after a change indicated by image information; FIG. 8 illustrates an example of the image before and after the change indicated by the image information; FIG. 9 illustrates an example of the image before and after the change indicated by the image information; FIG. 10 is a flow chart illustrating a procedure of a support process according to the first embodiment; and FIG. 11 illustrates a computer that executes a support program. DESCRIPTION OF EMBODIMENTS However, according to the above-mentioned technology in related art, in a case where the examination is to be carried out again on the wiring, the arrangement, and the like from the conceptual design, it is not simple for a user to determine which parts are parts subjected to a review in the conceptual design, parts where a review is not recommended, parts where a review can be carried out, and the like. For that reason, according to the technology in related art, a problem occurs that an operation in the carryover design is not efficient. A disclosed technology has been made in view of the above-mentioned circumstances, and an embodiment of the present disclosure provides a support program, a support apparatus, and a support method with which the carryover design can be supported more efficiently. Hereinafter, respective embodiments of a support apparatus, a support program, and a support method disclosed in the present application will be described in detail on the basis of the drawings. It is noted that this embodiment does not limit the disclosed technology. Then, the respective embodiments can be appropriately combined with each other as long as process contents do not become inconsistent. First Embodiment Configuration of Support Apparatus A support apparatus according to a first embodiment will be described. FIG. 1 illustrates a configuration of the support apparatus according to the first embodiment. From a storage unit that stores arrangement information on components and analysis information indicating a result of an analysis carried out on the components, a support apparatus 10 according to the present embodiment first reads out the arrangement information on the components and generates image information. Then, the support apparatus 10 according to the present embodiment reads out the analysis information corresponding to the components from the storage unit. Then, the support apparatus 10 according to the present embodiment changes a display attribution on the component included in the image information in accordance with the analysis information. As illustrated in FIG. 1 , the support apparatus 10 has an input unit 11 , an output unit 12 , a storage unit 13 , and a control unit 14 . The input unit 11 inputs various pieces of information to the control unit 14 . For example, the input unit 11 accepts an instruction for executing a support process which will be described below from a user and inputs the accepted instruction to the control unit 14 . Also, the input unit 11 accepts the arrangement information on the component on the circuit for supporting the circuit design or the like by the designer and inputs the accepted arrangement information on the component to the control unit 14 . As an example of the arrangement information on the component, for example, CAD (Computer Aided Design) data is exemplified. Also, the input unit 11 accepts the analysis information indicating the result of the analysis carried out on the components from a signal analysis apparatus 30 which will be described below and inputs the accepted analysis information to the control unit 14 . Also, the input unit 11 accepts revised edition information indicating a revision on the component and inputs the accepted revised edition information to the control unit 14 . Also, the input unit 11 accepts casing size information which is information related to a size of a casing that is a containment unit containing the circuit and inputs the accepted casing size information to the control unit 14 . As an example of a device of the input unit 11 , an operation accepting device such as a mouse or a key board is exemplified. The output unit 12 outputs various pieces of information. As an example of a device of the output unit 12 , a display device such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube) is exemplified. For example, in a case where the output unit 12 is the display device, the output unit 12 displays an image indicated by image information that is transmitted from a display unit 14 d which will be described below. The storage unit 13 stores various pieces of information. For example, the storage unit 13 stores arrangement information 13 a on the components, an analysis information DB (Data Base) 13 b , revised edition information 13 c , and casing size information 13 d. The arrangement information 13 a on the components is data indicating an arrangement of the respective components on the circuit. The arrangement information 13 a on the components is used by a generation unit 14 a which will be described below when image information on the image displayed on the output unit 12 is generated. It is noted that the arrangement information 13 a on the components also includes shapes of the respective components. FIG. 2 illustrates an example of respective components on a circuit indicated by arrangement information on the components. According to the example of FIG. 2 , a case is illustrated in which on a circuit 20 indicated by the arrangement information 13 a on the components, respective components including a component A 21 , a component B 22 , a component C 23 , a component D 24 , a resistance component 25 , a wiring component E 26 , a wiring component F 27 , and a wiring component G 28 are arranged. According to the example of FIG. 2 , the component A 21 transmits a signal via the wiring component E 26 , the resistance component 25 , and the wiring component F 27 to the component B 22 . Also, in the example of FIG. 2 , the component C 23 transmits a signal via the wiring component G 28 to the component D 24 . Herein, the component A 21 , the component B 22 , the component C 23 , and the component D 24 are components including, for example, an IC (Integrated Circuit) chip and the like. Also, the wiring component E 26 , the wiring component F 27 , and the wiring component G 28 are components that transmit a signal. The arrangement information 13 a on the components is stored by a registration unit 14 e which will be described below in the storage unit 13 . In the analysis information DB 13 b , the analysis information on the result of the analysis carried out on the components on the circuit is registered. For example, in the analysis information DB 13 b , a “net name” that is a name of a wiring (net) where a signal analysis is carried out, the number of times when the signal analysis is carried out, and a variation component model used for the signal analysis are registered by the registration unit 14 e for each wiring where the signal analysis is carried out. FIG. 3 illustrates an example of the analysis information DB. According to the example of FIG. 3 , a case is illustrated in which the signal analysis is carried out by 3 times on a wiring having a name of “NET A”, that is, the result of the signal analysis in the third time satisfies a predetermined criterion, and the variation component models used for the signal analysis are “Typ”, “Min”, and “Max”. It is noted that in the example of FIG. 3 , “O” indicates that the relevant variation component model is used for the signal analysis. On the other hand, in the example of FIG. 3 , “-” indicates that the relevant variation component model is not used for the signal analysis. Also, in the example of FIG. 3 , a case is illustrated in which the signal analysis is carried out by 2 times on a wiring having a name of “NET B”, that is, the result of the signal analysis in the second time satisfies the predetermined criterion, and the variation component model used for the signal analysis is “Typ”. Also, in the example of FIG. 3 , a case is illustrated in which the signal analysis is carried out by 2 times on a wiring having a name of “NET C”, that is, the result of the signal analysis in the second time satisfies the predetermined criterion, and the variation component models used for the signal analysis are “Typ” and “Min”. FIG. 4 illustrates an example of the result of the signal analysis. According to the example of FIG. 4 , the analysis result on the signal flowing through a wiring of signal analysis target which is analyzed by the signal analysis apparatus 30 that determines whether or not the signal of the analysis target is normal is illustrated. According to the example of FIG. 4 , a signal of the analysis result 31 illustrates a case in which a higher peak exceeds a threshold VIH and a lower peak is below a threshold VIL. In the above-mentioned case, the signal analysis apparatus 30 can perform the analysis in which the signal of the analysis target is normal. The revised edition information 13 c is revised edition information on the respective components. For example, the revised edition information 13 c indicates a release number of the respective components. The release number of the respective components is obtained via the input unit 11 from a component library that manages the release number of the components by a change unit 14 c and the registration unit 14 e which will be described below. The component library is, for example, an external apparatus and is configured to hold the latest release number of the respective components. Then, the registration unit 14 e stores the revised edition information 13 c in the storage unit 13 . FIG. 5 and FIG. 6 illustrate examples of the revised edition information. According to the example of FIG. 5 , a case is illustrated in which a release number of a component B is 1. FIG. 6 illustrates a case in which through a function addition or the like, a revised edition occurs in the component B and the release number of the component B becomes 2. The casing size information 13 d is information indicating a size of a casing storing a circuit. For example, in the casing size information 13 d , a region where the respective components on the circuit indicated by the arrangement information 13 a on the components can be stored is represented by three-dimensional positional coordinates. In a case where a component exists in the region indicated by the casing size information 13 d , it is determined that the component is contained in the casing. On the other hand, in a case where a component is out of the region indicated by the casing size information 13 d , it is determined that the component is not contained in the casing. The casing size information 13 d is obtained by the registration unit 14 e and stored in the storage unit 13 . The storage unit 13 is, for example, a semiconductor memory element such as a flash memory or a storage apparatus such as a hard disc or an optical disc. It is noted that the storage unit 13 is not limited by the above-mentioned type of the storage apparatus and may also be a RAM (Random Access Memory) or a ROM (Read Only Memory). The control unit 14 has an internal memory for storing a program that prescribes various process procedures and control data and executes various processes by using the program and the control data. As illustrated in FIG. 1 , the control unit 14 has the generation unit 14 a , a read section 14 b , the change unit 14 c , the display unit 14 d , and the registration unit 14 e. The generation unit 14 a reads out the arrangement information 13 a on the components from the storage unit 13 that stores the analysis information DB 13 b in which the arrangement information 13 a on the components on the circuit and the analysis information indicating the result of the analysis on the components are registered and generates image information. For example, the generation unit 14 a reads out the arrangement information 13 a on the components stored in the storage unit 13 . Then, the generation unit 14 a generates image information of the image displayed on the output unit 12 on the basis of the locations and the shapes of the respective components indicated by the read arrangement information 13 a on the components. The read section 14 b reads out various pieces of information. For example, the read section 14 b reads out the analysis information corresponding to the respective components the locations of which are indicated by the arrangement information 13 a on the components from the analysis information DB 13 b . The read of the analysis information will be described by way of a specific example. The read section 14 b searches the analysis information DB 13 b while names of the respective components the locations of which are indicated by the arrangement information 13 a on the components are used as keys. Then, in a case where a corresponding record is searched for from the analysis information DB 13 b , by obtaining a content of the record as the analysis information, the analysis information is read out. Also, the read section 14 b reads out the revised edition information 13 c stored in the storage unit 13 . Also, the read section 14 b reads out the casing size information 13 d stored in the storage unit 13 . The change unit 14 c changes display attributes of the components included in the image information in accordance with the analysis information. For example, among the respective components the locations of which are indicated by the arrangement information 13 a on the components, when the carryover design is carried out, the change unit 14 c determines the component where the corresponding analysis information is read out as the component where the review is not carried out because the signal analysis is already carried out and the components normally operate. In view of the above, the change unit 14 c changes the image information so that a display is made informing that the component where the corresponding analysis information is read out are the component where the review is not recommended, for example, a display is made in a manner that the component is displayed in gray which is less conspicuous than other colors. It is noted that the change unit 14 c can also change the display attribute so that the component where the corresponding analysis information is read out is displayed in a color having a lower brightness or saturation as compared with a display of the component where the corresponding analysis information is not read out, that is, the component where the signal analysis is not carried out. FIG. 7 illustrates examples of the image before and after the change indicated by the image information. According to the example on the left side in FIG. 7 , the respective components 21 to 27 of the circuit 20 indicated by the image information 13 a before the change by the change unit 14 c are illustrated. In the case of the example on the left side in FIG. 7 , when the analysis information corresponding to the wiring component G 28 is read out from the analysis information DB 13 b , the change unit 14 c performs the following process as illustrated in the example on the right side in FIG. 7 . That is, the change unit 14 c changes the image information so that a display is made informing that all the components existing in a section from the component C 23 that transmits the signal flowing through the wiring component G 28 where the signal analysis is carried out until the component D 24 that receives this signal are the components where the review is not recommended. According to the example on the right side in FIG. 7 , the change unit 14 c changes the image information so that a display is made in a manner that the component C 23 , the wiring component G 28 , are the component D 24 are displayed in gray which is less conspicuous than other colors. The image information changed in the above-mentioned manner is used as the image information on the image displayed on the output unit 12 at the time of the conceptual design in the carryover design. Therefore, at the time of the carryover design, the designer who designs the circuit or the like can figure out which component is the component where the review is not recommended. With this configuration, it is possible to more efficiently support the carryover design. It is noted that the change unit 14 c may perform a display indicating that the component where the corresponding analysis information is read out and also where the number of times when the signal analysis is carried out which is indicated by the analysis information exceeds a predetermined value is the component where the review is not recommended. For example, the change unit 14 c may change the image information so that the component where the number of times when the signal analysis is carried out exceeds two is displayed in gray which is less conspicuous than other colors. With this configuration, the designer or the like can figure out that the component where the designer or the like experiences hardships in the signal analysis while the number of times when the signal analysis is carried out exceeds the predetermined value is the component where the review is not recommended at the time of the carryover design. It is noted that the change unit 14 c can also change the display attribute so that a display of the component where the number of times when the signal analysis is carried out exceeds the predetermined value is made in a color having a lower brightness or saturation as compared with a display of the component where the number of times when the signal analysis is carried out does not exceed the predetermined value. Also, the change unit 14 c changes the display attribute of the image information on the basis of the revised edition information 13 c so that a display is made informing that the component the revised edition of which is generated is the component where the review is recommended. This is because a function may be changed in the component the revised edition of which is generated, and therefore the review is preferably recommended in many cases in the carryover design. For example, the change unit 14 c obtains the latest release numbers of the respective components on the circuit 20 indicated by the arrangement information 13 a on the components via the input unit 11 from the component library. Then, the change unit 14 c compares the release numbers of the respective components on the circuit 20 indicated by the arrangement information 13 a on the components which are the release numbers of the respective components indicated by the revised edition information 13 c with the obtained latest release numbers of the respective components on the circuit 20 and identifies the component the revised edition of which is generated. Subsequently, the change unit 14 c changes the image information so that a display is made informing that the component the revised edition of which is generated is the component where the review is recommended, for example, the component is displayed in red which is more conspicuous than other colors. It is noted that the change unit 14 c can also change the display attribute so that a display of the component the revised edition of which is generated is made in a color having a higher brightness or saturation as compared with a display of the component with no revised edition. FIG. 8 illustrates an example of the image before and after the change indicated by the image information. According to the example on the left side in FIG. 8 , the respective components 21 to 27 of the circuit 20 indicated by the image information 13 a before the change by the change unit 14 c are illustrated. In the case of the example on the left side in FIG. 8 , when the components A 21 , B 22 , 25 , E 26 , and F 27 are subjected to the revised edition, the change unit 14 c performs the following process as illustrated in the example on the right side in FIG. 8 . That is, the change unit 14 c changes the image information so that a display is made informing that the respective components of the components A 21 , B 22 , 25 , E 26 , and F 27 are the components where the review is recommended. According to the example on the right side in FIG. 8 , the change unit 14 c changes the image information so that the components A 21 , B 22 , 25 , E 26 , and F 27 are displayed in red which is more conspicuous than other colors. The image information changed in the above-mentioned manner is used as the image information on the image displayed on the output unit 12 at the time of the conceptual design in the carryover design. Therefore, at the time of the carryover design, the designer who designs the circuit or the like can figure out which component is the component where the review is recommended. With this configuration, it is possible to more efficiently support the carryover design. Also, the change unit 14 c changes the display attribute of the image information on the basis of the casing size information 13 d so that a display is made informing that the component which is not to be contained in the casing is the component where the review is recommended. This is because the component which is not to be contained in the casing is subjected to the review at the time of the carryover: design. For example, the change unit 14 c obtains the casing size information 13 d via the input unit 11 . Then, the change unit 14 c identifies the component out of the region indicated by the casing size information 13 d among the components on the circuit 20 indicated by the arrangement information 13 a on the components. Then, the change unit 14 c identifies all the components existing in a section from the component that transmits the signal flowing through the identified component until the component that receives this signal. Subsequently, the change unit 14 c changes the image information so that a display is made informing that the identified component is the component where the review is recommended, for example, the component is displayed in red which is more conspicuous than other colors. It is noted that the change unit 14 c can also change the display attribute so that the component which is not to be contained in the casing is displayed in a color having a lower brightness or saturation as compared with a display of the component which can be contained in the casing. FIG. 9 illustrates an example of the image before and after the change indicated by the image information. According to the example on the left side in FIG. 9 , the respective components 21 to 27 of the circuit 20 indicated by the image information 13 a before the change by the change unit 14 c are illustrated. According to the example on the left side in FIG. 9 , in a case where the component out of a region 40 indicated by the casing size information 13 d is the component C 23 , the change unit 14 c performs the following process as illustrated in the example on the right side in FIG. 9 . That is, the change unit 14 c identifies the component C 23 out of the region 40 . Then, the change unit 14 c changes the image information so that a display is made informing that all the components existing in a section from the component C 23 itself that transmits the signal flowing through the identified component C 23 until the component D 24 that receives this signal are the components where the review is recommended. According to the example on the right side in FIG. 9 , the change unit 14 c changes the image information so that the components C 23 , D 24 , and G 28 are displayed in red which is more conspicuous than other colors. The image information changed in the above-mentioned manner is used as the image information on the image displayed on the output unit 12 at the time of the conceptual design in the carryover design. Therefore, at the time of the carryover design, the designer who designs the circuit or the like can figure out which component is the component where the review is recommended. With this configuration, it is possible to more efficiently support the carryover design. It is noted that in a case where the change unit 14 c receives an instruction by the user such as the component where the review is recommended via the input unit 11 , with regard to the component where the review is recommended, the image information may be changed so that a display is made informing that the review is recommended. Similarly, in a case where the change unit 14 c receives an instruction by the user such as the component where the review is not recommended via the input unit 11 , with regard to the component where the review is not recommended, the image information may be changed so that a display is made informing that the review is not recommended. The display unit 14 d performs a control so as to display the image indicated by the image information that is changed by the change unit 14 c . For example, the display unit 14 d outputs the image information changed by the change unit 14 c to the output unit 12 . With this configuration, by the output unit 12 , the image indicated by the image information changed by the change unit 14 c is displayed. The registration unit 14 e registers or stores information. For example, the registration unit 14 e obtains the arrangement information 13 a on the components via the input unit 11 and stores the obtained arrangement information 13 a on the components in the storage unit 13 . Also, the registration unit 14 e obtains the analysis information via the input unit 11 and registers the obtained analysis information in the analysis information DB 13 b . Also, the registration unit 14 e obtains the revised edition information 13 c on the respective components indicated by the arrangement information 13 a on the components via the input unit 11 from the component library at predetermined temporal intervals, for example, at intervals of one week and stores the obtained revised edition information 13 c in the storage unit 13 . Also, the registration unit 14 e obtains the casing size information 13 d via the input unit 11 and stores the obtained casing size information 13 d in the storage unit 13 . The control unit 14 is an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array) or an electronic circuit such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Flow of Process Next, a flow of a process by the support apparatus 10 according to the present embodiment will be described. FIG. 10 is a flow chart illustrating a procedure of a support process according to the first embodiment. This support process is executed in a case where an instruction for executing the support process is input from the input unit 11 to the control unit 14 . As illustrated in FIG. 10 , the generation unit 14 a reads out the arrangement information 13 a on the components from the storage unit 13 that stores the analysis information DB 13 b in which the arrangement information 13 a on the components on the circuit and the analysis information indicating the result of the analysis on the components are registered and generates image information (step S 101 ). The read section 14 b reads out the analysis information corresponding to the respective components from the analysis information DB 13 b the arrangement of which is indicated by the arrangement information 13 a on the components (step S 102 ). The read section 14 b reads out the revised edition information 13 c stored in the storage unit 13 (step S 103 ). The read section 14 b reads out the casing size information 13 d stored in the storage unit 13 (step S 104 ). The change unit 14 c changes the display attribute of the image information in accordance with the analysis information, the revised edition information 13 c , and the casing size information 13 d (step S 105 ). Effect of First Embodiment As described above, the support apparatus 10 according to the present embodiment reads out the arrangement information 13 a on the components from the storage unit 13 that stores the arrangement information 13 a on the components and the analysis information indicating the result of the analysis on the components and generates the image information. Then, the support apparatus 10 according to the present embodiment reads out the analysis information corresponding to the components from the storage unit 13 . Then, the support apparatus 10 according to the present embodiment changes the display attribute of the image information in accordance with the analysis information, the revised edition information 13 c , and the casing size information 13 d . Therefore, with the support apparatus 10 according to the present embodiment, it is possible to more efficiently support the carryover design. Also, in a case where the analysis information indicates that the signal analysis is carried out, the support apparatus 10 according to the present embodiment changes the display attribute of the image information so that a display is made informing that the component corresponding to the analysis information is the component where the review is not recommended. Therefore, with the support apparatus 10 according to the present embodiment, at the time of the carryover design, the designer who designs the circuit or the like can figure out which component is the component where the review is not recommended. Also, in a case where the analysis information indicates that the signal analysis is carried out and the number of times when the signal analysis is carried out exceeds a predetermined threshold, the support apparatus 10 according to the present embodiment can change the display attribute of the image information so that a display is made informing that the component corresponding to the analysis information is the component where the review is not recommended. With this configuration, the designer or the like can figure out that the component where the designer or the like experiences hardships in the signal analysis while the number of times when the signal analysis is carried out exceeds the predetermined value is the component where the review is not recommended at the time of the carryover design. Also, the support apparatus 10 according to the present embodiment changes the display attribute of the image information on the basis of the revised edition information 13 c of the component so that a display is made informing that the component the revised edition of which is generated is the component where the review is recommended. Therefore, with the support apparatus 10 according to the present embodiment, at the time of the carryover design, the designer who designs the circuit or the like can figure out which component is the component where the review is recommended. Also, the support apparatus 10 according to the present embodiment changes the display attribute of the image information on the basis of the casing size information 13 d on the casing that is the containment unit containing the components so that a display is made informing that the component which is not to be contained in the casing is the component where the review is recommended. Therefore, with the support apparatus 10 according to the present embodiment, at the time of the carryover design, the designer who designs the circuit or the like can figure out which component is the component where the review is recommended. Incidentally, the embodiment related to the disclosed apparatus has been described in the above, but the present disclosure may also be implemented in various different modes other than the above-mentioned embodiment. In view of the above, other embodiments included in the present disclosure will be described hereinafter. For example, all or a part of the processes described as being automatically carried out among the processes described according to the first embodiment can also be manually carried out. Also, all or a part of the processes described as being manually carried out among the respective processes described according to the present embodiment can be automatically carried out through a method in related art. Also, the processes in the respective steps of the respective processes described according to the respective embodiments can be arbitrarily divided or integrated in accordance with various loads, use situations, or the like. Also, a step can be omitted. For example, steps S 102 , S 103 , and S 104 illustrated in FIG. 10 can be integrated. Also, the order of the processes in the respective steps of the respective processes described according to the respective embodiments can be changed in accordance with the various loads, the use situations, or the like. Also, the respective constituent elements of the illustrated respective apparatus are conceptual in terms of functions and may not be configured physically as illustrated in the drawings. That is, specific states of the dispersion and the integration of the respective apparatus are not limited to the illustrated examples, and all or a part of the constituent elements can be configured dispersed or integrated functionally or physically in an arbitrary unit in accordance with the various loads, the use situations, or the like. For example, the generation unit 14 a and the read section 14 b illustrated in FIG. 1 may be integrated with each other. Second Embodiment Support Program Also, the various processes by the support apparatus 10 described according to the above-mentioned first embodiment can be realized while a previously prepared program is executed by a computer system such as a personal computer or a work station. In view of the above, hereinafter, by using FIG. 11 , an example of a computer that executes a support program having a function similar to the support apparatus described according to the above-mentioned embodiment will be described. FIG. 11 illustrates a computer that executes a support program. As illustrated in FIG. 11 , a computer according to a second embodiment has a CPU (Central Processing Unit) 310 , a ROM (Read Only Memory) 320 , an HDD (Hard Disk Drive) 330 , and a RAM (Random Access Memory) 340 . The respective units 310 to 340 are connected via a bus 350 . The ROM 320 previously stores a support program 320 a exhibiting a function similar to the generation unit 14 a , the read section 14 b , and the change unit 14 c illustrated according to the above-mentioned embodiment. It is noted that the support program 320 a may appropriately be separated. Then, the CPU 310 reads out the support program 320 a from the ROM 320 for execution. Then, the HDD 330 is provided with arrangement information on components, an analysis information DB, revised edition information, and casing size information. The arrangement information on the components, the analysis information DB, the revised edition information, and the casing size information corresponds to the arrangement information 13 a on the components, the analysis information DB 13 b , the revised edition information 13 c , and the casing size information 13 d , respectively. Then, the CPU 310 reads out the arrangement information on the components, the analysis information DB, the revised edition information, and the casing size information to be stored in the RAM 340 . Furthermore, the CPU 310 executes the support program by using the arrangement information on the components, the analysis information DB, the revised edition information, and the casing size information stored in the RAM 340 . It is noted that all of the respective pieces of data stored in the RAM 340 may not be stored in the RAM 340 , and it suffices that only data used for the process may be stored in the RAM 340 . It is noted that the above-mentioned support program may not be stored in the ROM 320 from the beginning. For example, the program is stored in “portable physical media” such as a flexible disc (FD), a CD-ROM, a DVD disc, an opto-magnetic disc, and an IC card to be inserted into a computer 300 . Then, the computer 300 may read out the program from the media for execution. Furthermore, the program is stored in “another computer (or a server)” and the like that are connected to the computer 300 via a public line, the internet, a LAN, a WAN, or the like. Then, the computer 300 may read out the program from the other computer and the like for execution. All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and changes could be made hereto without departing from the spirit and scope of the invention.	A computer-readable medium storing a support program that causes a computer to execute operations, the operations including reading out, from a memory that stores arrangement information on a component on a circuit and analysis information indicating a result of an analysis on the component, the arrangement information on the component and generating image information, reading out the analysis information that is information related to whether or not an examination is to be carried out with respect to the component from the memory, and changing a display attribute of the component which is included in the image information in accordance with the analysis information.	6
TECHNICAL FIELD This invention relates to tractor vehicles having a retractable king pin to which a trailer vehicle may be connected and has particular reference to a vertically moveable king pin that is operated from a remote part of the vehicle. BACKGROUND OF THE INVENTION Tractor and trailer combinations are increasingly being used for transportation of livestock and other commodities. The tractor vehicles are generally of a specialized nature, especially for highway use. There is, however, a need for a generalized type of tractor vehicle that can be used for general truck purposes. This need has led to the widespread use of pickup trucks and general utility trucks as tractor vehicles wherein the trailer hitch or king pin is mounted on the bed of the truck rather than at the tailgate or rear end of the truck. These tractor-trailer combinations are generally referred to as fifth wheel tractor-trailer combinations. When, however the trailer is disconnected and the tractor-truck is used for general hauling, means must be provided to remove the king pin from the bed of the truck so that a flat uninterrupted bed can be formed. Various mechanisms have been used to move the king pin including gearing arrangements, spring loaded pins, and hinged pins. Most such arrangements heretofore required the operator to mount the bed of the truck to manipulate the mechanisms. BRIEF DESCRIPTION OF THE INVENTION The king pin of the present invention is vertically moveable from a position below the bed of a tractor truck to a position projecting above the bed of the truck. A manually rotatable shaft extends from the king pin to the exterior of the bed of the truck and the rear edge of the truck is presently preferred as the exterior location for the outer end of the shaft. A crank or other rotating mechanism is provided for manually rotating the shaft. A rack and gear arrangement is presently preferred as the mechanism for vertically moving the king pin. The king pin is mechanically secured in its elevated position by means of a sliding bolt that is spring biased to maintain the bolt in a hole in the king pin. The sliding bolt locks the pin to a structurally strong housing including support beams permanently built into the frame structure of the tractor truck. A sliding rod extends from the sliding bolt to the exterior of the bed of the truck, and its outer end is preferably located adjacent to the outer end of the rotary shaft. The sliding rod is manually pulled to release the bolt from the king pin so that the king pin can be retracted by rotating the rotatable shaft. The apparatus is operated from the exterior of the truck bed. No tools are needed to remove or retract the projecting king pin. Two manual controls extend to the exterior of the truck bed, one to pull the bolt out of engagement with the king pin and the other to retract the king pin. In this fashion the driver of the vehicle can readily convert the truck from a fifth wheel tractor to a cargo carrying flatbed truck with no protrusions in the flatbed. When it is desired to project the king pin, the gear is manually rotated and engages the rack to elevate the king pin. When the hole of the king pin is opposite the bolt, the spring biased bolt snaps into the king pin hole. This ease of manual conversion is accompanied by great mechanical security against the king pin retracting while in use. BRIEF DESCRIPTION OF THE DRAWINGS Various objects, advantages and features of the invention will be apparent in the following description and claims considered together with the drawings forming an integral part of the application, in which: FIG. 1 is a three dimensional view of the bed of a tractor truck above which the king pin projects and showing the rotatable shaft and sliding rod extending to the rear edge of the bed. FIG. 2 is an exploded three dimensional view on an enlarged scale of the mechanical parts of the invention of FIG. 1 including a rack and gear elevating and depressing mechanism for the king pin and the sliding bolt structure, but with the upper horizontal plate removed. FIG. 3 is a three dimensional view of a modified form of king pin having a generally rectangular cross section and vertically slideable in a rectangular guide. DETAILED DESCRIPTION Referring to FIG. 1, there is illustrated a bed 10 of a tractor vehicle having side edges 11, a rear edge 12 and a top surface 13. Cut within the top surface 13 is a rectangular opening 14 which is preferably closed by hinged covers 16 which form a flat surface when closed. Projecting upwardly above the bed 13 is a king pin 17 preferably equally distant from each side edge 11. The king pin 17 is disposed in the housing 15 which includes transverse frame members 19, a guide 18 and a horizontal plate 20 welded or otherwise secured to the transverse frame members 19. Illustrated in more detail in FIG. 2 is the housing 15 and other mechanical parts of the invention. It will be noted that the vertical guide 18 may be welded or otherwise secured to the transverse frame members 19. The housing 15 has a vertical bore 21 and a horizontal bore 22. The king pin 17 reciprocates within the bore 21 and the king pin may have various shapes of its upper end of which the round ball type is the most common and is illustrated at 23. The king pin 17 has a vertical rack 24 which has teeth formed by cutting into the periphery of the king pin. The king pin 17 also has a transverse or horizontal hole 26 of the same general diameter as the transverse bore 22 in the housing 20. The king pin 17 is elevated and retracted by means of a spur gear 27 engaging the teeth of the rack 24. For this purpose, a slot 28 is formed in the sidewall of the guide 18, and the spur gear 27 projects into that slot 28 to engage the rack 24. The gear 27 is mounted on a rotary shaft 29, one end of which fits in a bearing hole 31, and the other end is provided with a crank 30. This crank is the same as that illustrated in FIG. 1 and preferably projects out the rear of the vehicle bed 10. Also illustrated in FIG. 2 is the bolt that locks the king pin 17 in an extended position, as shown in FIG. 1. A cylindrical bolt 32 is of a diameter to fit in the horizontal bore 22 of the housing 20 and into also the horizontal bore 26 in the king pin 17. Therefore, when the king pin 17 is disposed within the guide 18 shown in FIG. 1, then the bolt 32 passes through the king pin 17 by means of its hole 26, thereby securely locking the king pin 17 to its housing 15. The bolt 32 is maintained in its locking position by means of a compression spring 33, bearing against one end of the bolt 32 and the other end against an apertured plate 34 forming part of the bed structure of the truck. The bolt moved is to the rear of the bed 10, as viewed in FIG. 1, and to the left as viewed in FIG. 2, by means of a mechanical pull rod 36 connected to the bolt 32, and the other end passes through a bearing 37 in the rear edge 12 of the truck and terminates in an enlargement or ball 38 that may be easily manually grasped by an operator. The spring 33 normally urges the bolt to the right to pass it through the horizontal housing bore 22 and the horizontal bore 26 in the king pin 17. When it is desired, however, to retract the ball, the pin is pulled to the left, as viewed in FIG. 2, by manually pulling on the knob or ball 38 of the rod 36. Referring to FIG. 3, there is illustrated a modified form of the invention wherein a king pin 41 has a square cross section and fits within a guide 42 which is also of a square cross section and may have a horizontal bore (not shown) through which a pin can act to contact a horizontal hole 43 in the king in 41. This construction prevents rotation of the king pin about its longitudinal axis. It will be appreciated by those in the art that king pins do not all terminate in an upper ball, but they may have various shapes such as a T-shaped profile which is also commonly used. OPERATION The device is shown in its extended or upward position in FIG. 1 and in that position the bolt 32 of FIG. 2 passes through the housing horizontal bore 22 and through the hole 26 in the king pin 17 and through a second housing bore 22 (not shown) to lock the king pin in its upward position shown in FIG. 1. The bolt is maintained in its locking position by means of the compression spring 33. When it is desired to lower the king pin 17, then the operator manually pulls on the knob 38 to the left, and this pulls the pin 32 to the left against the compression of spring 33. The operator then rotates the spur gear 27 in a counterclockwise direction, and this causes the pin to reciprocate downwardly in the guide 18 because of the contact of the teeth of the spur 27 with the teeth of the rack 24 formed in the king pin 17. The downward movement of the king pin 17 is halted by means of a mechanical stop 39 secured to the housing 15. When it is desired to elevate the king pin 17, as shown in FIG. 1, then the spur gear 27 is rotated clockwise and its teeth engaging the rack 24 cause the king pin to move upwardly. During this upward movement, the bolt 32 will be urged by spring 33 against the pin 17, and when the pin hole 26 is in alignment with the bolt 32, then the bolt will move into the hole 26 to lock the pin. The horizontal bore 22 and the housing 15 is preferably duplicated on the far side of the guide 18 and through the metal of the transverse frame member 19. It will be appreciated that the round king pin 17 fitting in round guide 18 might be subject to rotation, in which case the bolt 32 would not be able to pass through the hole 26 in the king pin. The king pin 17 is elongated, and rotation would take place about its longitudinal axis. The correct alignment, however, from a rotational standpoint, is maintained by the interfitting of the teeth of the gear 27 with the recesses between the teeth of the rack 24. This problem does not arise, however, with the king pin of FIG. 3, inasmuch as the square or rectangular cross section of the king pin 41 and the bore in the guide 42 are both rectangular cross sections, preventing any rotation. The invention has been described with respect to its presently preferred embodiment as required by the statues. Variations and modifications of the disclosed structure will occur to those skilled in the art. For example, the hole 26 in the king pin 17 need not be a through hole, but the through hole and double support of the bolt on the housing is preferable. All such variations and modificatins that fall within the true spirit and scope of the invention are included within the scope of the following claims:	A flat bed vehicle has a king pin mounted in the flat bed for connection to a trailer to create a fifth wheel tractor-trailer combination. The king pin is vertically reciprocated above the flat bed and below the flat bed by a hand crank located at an outside edge of the flat bed. The king pin is held in its upward position by means of a horizontal bolt passing through a hole in the king pin. The bolt is manually removed from the king pin, for lowering the king pin, by a manual pull rod extending to the exterior of the vehicle bed, preferably adjacent to the hand crank.	1
BACKGROUND OF INVENTION [0001] 1 . Field of the Invention [0002] This invention relates to apparatus for placing tubulars in a well using a drilling rig. More particularly, apparatus is provided for remotely controlling alignment of joints of tubulars before joining. [0003] 2 . Description of Related Art [0004] The placement of tubulars in wells is normally carried out by hoisting a single joint of tubular (normally 30-45 ft. in length) into a vertical position over an assembly of tubulars (string) already placed in the well, aligning the hoisted joint of tubular with the string of tubulars, which is hanging in the well and supported by slips, rotating the hoisted tubular to thread the tubular into the string, raising the extended string to release the slips and lowering the extended string into the well. The process is repeated to make up a tubular string of the required length. [0005] Tubulars having an outside diameter from about 2⅜ inches to about 36 inches are placed in wells. Tubulars placed in a well after the hole is drilled are called “casing,” and the diameter is normally more than 5 inches. Smaller tubulars, used as conduits for fluid flow in the well, are called “tubing.” Tubing is usually placed in a well using a “work over” rig, but it has the same type apparatus for running tubulars as a drilling rig, and is included in the designation “drilling rig” herein. A variety of automated equipment has been developed for placing both tubing and casing in wells. In most wells, where automated equipment is not available or is not economically justified, the placement of tubulars is still a “hands on” operation. The pipe tongs used to rotate tubulars during a placement operation are often hydraulically powered. Slips are usually handled manually, but may be hydraulic. The hoisting of each joint of tubular into a vertical position is performed with a small hoist in a mast over the well. The lowering of the entire string in the well is performed with the block-and-cable apparatus common to drilling rigs. The required lifting capacity of the mast is usually determined by the weight of the casing. [0006] When a joint of tubular is in the vertical position, it must be aligned so that threading into the string of tubulars will not damage threads in the tubular. Generally, the joint being added has the male connection and the process of bringing the joints into position for threading is called “stabbing” the upper joint. When casing is being placed in a well each joint is much heavier than tubing joints, so aligning and stabbing casing are more difficult operations. The alignment operation is normally performed by a man standing on a platform in the mast (“derrick man”), which may be 30-50 ft. above the rig floor. Safety considerations arise when a man is required to stand above the level of the rig floor, because of the danger of falling. At the same time, it is necessary to thread the joints together without damaging threads in the tubular, which, with casing, can cause fluid to leak from the well and require expensive remediation steps to prevent an environmental risk. [0007] U.S. Pat. App. No. 2012/0085550 discloses method and apparatus for stabbing tubular goods using an assembly attached to an elevator in a conventional drilling rig or a casing-running tool used in top drive drilling rigs. U.S. Pat. No. 7,770,654 discloses a pipe handling device for use with a top drive rig. [0008] What is needed is apparatus for aligning tubulars for joining, without the need for a person positioned above the rig floor, that is economical to build and operate and that easily adapts for use with the variety of drilling rigs widely used in industry. BRIEF SUMMARY OF THE INVENTION [0009] Apparatus is provided to be placed on the floor of a drilling rig, either conventional or top drive, which can be remotely operated to align tubulars, such as casing, for making threaded connections at the drill floor. Hydraulic or pneumatic cylinders or electrically-driven sources of force operate plates and fingers to control the location and orientation of a tubular as it hangs in an elevator and align the tubular with a connector on a mating second tubular, such that lowering and rotation of the first tubular with low torque makes a threaded connection. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) [0010] FIG. 1 shows an isometric view of the tubular aligning assembly. [0011] FIG. 2 shows an isometric front view of the finger assembly of the tubular arm assembly. [0012] FIG. 3 shows an isometric rear view of the finger assembly of the tubular arm assembly. [0013] FIG. 4 shows an isometric detail view of one embodiment of a driving mechanism for fingers of the tubular arm assembly. [0014] FIG. 5 shows a plan view of fingers of the assembly in an open position. [0015] FIG. 6 shows a plan view of fingers of the assembly in a closed position. [0016] FIG. 7 shows an isometric detail view of a second embodiment of a driving mechanism for fingers of the tubular arm assembly. [0017] FIG. 8 shows a plan view of fingers of the assembly in an open position. DETAILED DESCRIPTION OF THE INVENTION [0018] Referring to FIG. 1 , one embodiment of a tubular aligning assembly 10 is shown. Assembly 10 is adapted to be placed on the drilling floor of a top drive drilling rig or to be placed on the rotary table of a conventional rotary rig. Base plate 11 , which may be 2-inch thick steel, forms the base of the assembly. Attached plate 11 a contains slot 11 b and is preferably removable from base plate 11 by operation of fasteners 11 c. The size of slot 11 b is determined by the size of the tubulars being placed in a well. Attached plate 11 a may have pad eyes 11 c that are adapted to receive slots on the bottom of slips. Post base assembly 12 a supports gear 12 having teeth that mesh with a motor attached to 12 a such that post 13 may be rotated by operation of the motor. Post base assembly 12 a may have supports 12 b. Post 13 may be adjustable in height by a movable pin passing through holes in two concentric sections of the post and post support 13 a, or, in another embodiment, height may be remotely controlled by a hydraulic or pneumatic cylinder inside post 13 (not shown). Extendable box assembly 15 supports finger assembly 20 . Fixed box member 14 may be attached to support member 14 a and post 13 . Movable box member 15 may be extended and retracted within fixed box member 14 by operation of cylinder 16 , which is attached to member 14 and member 15 . Finger assembly 20 is attached to movable box member 15 . Fixed box member 14 may include slot 14 b, which allows retraction of finger assembly 20 nearer post 13 . [0019] Alternatively, in another embodiment, fixed box member 14 may be attached to a fixed structure of a drilling rig, such as one or more vertical members of the mast of the rig. In this embodiment, base 11 and post 13 are not used, and operations of the apparatus may be performed with other elements as if base 11 and post 13 were supporting fixed box member 14 . [0020] FIG. 2 illustrates an isometric front view of finger assembly 20 . Finger base plate 21 supports upper pair of fingers 22 , having distal pasts 22 a and 22 b, and lower pair of fingers 23 , having distal parts 23 a and 23 b . Pair of fingers 22 and 23 may include roller bearings or ball bearings (not shown) inside each finger to decrease resistance to rotation of a tubular confined by and being aligned by the fingers. Distal parts 22 a and 22 b of upper fingers 22 are preferably in different horizontal planes, such that the distal parts of the fingers overlap when the fingers close. The same feature may be used for distal parts 23 a and 23 b of lower fingers 23 . Distal parts of all fingers may not be necessary and may be omitted for some pipe sizes and applications. Rotary bearing 25 provides for rotation of finger base plate 21 around box member 15 . [0021] In another embodiment, only one pair of pairs of fingers 22 or 23 may be present in finger assembly 20 , but not both. It may not be necessary to have two pairs of fingers, as shown in FIG. 2 and FIG. 3 , in some applications. The thickness of the fingers in one pair of fingers may be increased to provide an adequate source of torque transverse to the axis of a tubular. The driving mechanism for only one pair of fingers is required in this embodiment. [0022] FIG. 3 illustrates an isometric rear view of finger assembly 20 having two pairs of fingers. Finger support plate 30 is attached to finger base plate 21 and the extended end of box member 15 by horizontal pin 34 , disposed so as to allow tilting of support plate 30 by rotation around the pin. Force for control of tilting is supplied by cylinder 31 . Rotation of finger base plate 21 with respect to finger support plate 30 is provided by rotary bearing 25 ( FIG. 2 ). Force for rotation is supplied by cylinder 32 . Alternatively, the force may be supplied by an electric motor. Cylinders 37 and 38 supply the forces to operate the finger assembly, as described below. [0023] Referring to FIG. 4 , one embodiment of a driving mechanism 40 for upper and lower pairs of fingers is illustrated. The same driving mechanism is used for upper and lower pairs of fingers. The position of piston 41 of cylinder 37 , extending through a hole in finger base 18 controls the position of fingers 22 . H-member 43 is rigidly attached to piston 41 . The proximate ends of links 45 are pivotally and moveably attached to H-member 43 by bushings 44 . The distal ends of links 45 are pivotally and moveably attached to fingers 22 by bushings 46 . Fingers 22 are pivotally and rigidly attached to horizontal U-member 42 by bushings 47 . Therefore, bushings 44 and 46 move linearly (hence, are “movably attached”) in response to linear movement of piston 41 , while bushings 47 remain fixed (hence, pivotally and rigidly attached). Driving mechanism 40 converts linear movement of the piston into angular movement of the fingers. In another embodiment, opening and closing of fingers may be achieved by a rack and pinion mechanism, described below. It should be understood that, although hydraulic or pneumatic cylinders are illustrated and described herein to provide driving forces, in other embodiments, driving forces provided by any or all of the cylinders can be provided by electric motors and associated gears. [0024] FIG. 5 illustrates fingers 22 in an open position, to be used for placing the fingers around a tubular and beginning to grasp the tubular. FIG. 6 illustrates fingers 22 in a closed position. Contour 22 c may be adapted for different diameters or ranges of diameters of tubulars. [0025] Referring to FIG. 7 , another embodiment of a driving mechanism for a pair of fingers is shown. Driving mechanism 70 operates as a rack and pinion. Finger base plate 78 supports horizontal U-member 72 . Fingers 79 are pivotally and rigidly attached to member 72 by bushings 77 . Movement of piston 71 (or other source of force) causes member 74 , having teeth 73 , to move linearly. Teeth 75 in fingers 79 translate linear movement into angular movement of fingers 79 . [0026] All embodiments of a tubular aligning assembly disclosed herein may be used for placing any tubulars in a well with a rig; only casing will be discussed here. Assembly 10 may be placed on the floor of a drilling or completion rig. In another embodiment, post base assembly may be rigidly attached to one or more rigid members of the rig, such as a vertical member of the mast or the drill floor or substructure. Finger assembly 20 may then be operated to align the tubular being added to the tubulars in the well. A joint of casing, normally with male threads, is suspended in the mast by elevators. Slips support a string of casing that has been placed in a well, with a female connector above the slips. Normally, the position of elevators in a horizontal plane does not allow a joint to align with the connector such that the joint can be rotated at low torque, which is necessary to insure that threads on the joint and connector are properly mated. Preferably, some threads are engaged by manual force before tongs are applied to torque the connection to the recommended level. This minimizes the risk of cross-threading the connection, which is especially important in placing casing in a well. Operation of the cylinders or other apparatus to supply a driving force in the apparatus from a control panel allows alignment of a joint such that it can be joined to a connector by pipe threads at low torque even if the elevator is not vertically above the joint. The control panel may be on or off the drill floor. Observation of tubular alignment may be by visual observation and communication to an operator of the control panel, by a video camera and viewing screen for the panel operator or other sensors and communication channels for detecting the location of a joint with respect to a connector and communicating data to the panel operator. [0027] Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.	Apparatus is provided for aligning tubulars when a drilling rig is used to lower a string of tubulars into a well. A joint of tubular can be moved to a vertical position above a connector to which it is to be joined and placed at the angle where threads on the joint and connector can be joined at low torque without damage to the threads. The apparatus can be used on a variety of drilling rigs and provides a safer environment for workers on the rig.	4
RELATED INVENTIONS [0001] This application is a Continuation-in-Part of my co-pending application Ser. No. 12/022,051 filed on Jan. 29, 2008, for Resin Mixing and Cable Tensioning Device and Assembly For Cable Bolts. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a device and assembly for cable bolt systems. In particular, the present invention relates to cable bolt apparatus which can be used to both mix associated cable resin and to tension the cable bolt assembly against a bearing plate. [0004] 2. Background and Related Art [0005] Steel bolts and cable bolts are commonly used in underground mines to stabilize geologic layers adjacent mine openings. For example, cable bolt assemblies are used to secure the geologic layers of the roof of a mine tunnel or drift to prevent roof strata from falling and causing obstructions or injury to persons or equipment in the tunnel. [0006] Rigid members such as steel rods or rebar have long been used in anchoring systems in construction applications and as rock bolts in mining applications. For example, threaded rebar manufactured and sold by DYWIDAG under the brand name Threadbar has been used for rock bolts for years. Anchoring such rods or rebar at one end or at both ends allows the rod to bear a tension load. Steel rods have been particularly useful in anchoring applications because threads can be formed on the outer surface of the rods to receive desired bolts with corresponding threads or to receive other fastening devices such as a Frazer-Jones D9 expansion shell assembly. Rigid steel rods are, however, not always ideal because they are manufactured in finite, fixed lengths and long rods are often difficult to work with in confined spaces such as construction and mining sites. Rigid rods can also be subject to shearing stresses if, for example, there is ground movement adjacent the rod in a mining application. [0007] Steel cables comprising multiple strands of steel have also been used as anchoring systems. Unlike rigid, steel rods, cables provide some flexibility along their length. That is, a cable can bent around an object or deflect when subject to ground movement adjacent the cable. In some instances, steel cable is easier to use in confined spaces. Historically, anchoring a cable at one or both ends is more difficult because the cable does not bear threads to receive bolts. A number of cable anchoring methods have been used. One example is a multistrand anchorage device which separates strands of the cable and anchors each strand individually or in groups such as the DYWIDAG Multistrand Posttensioning System. Another example comprises positioning a thread-bearing sleeve along the length of the cable at the desired locations to receive a desired bolt or Frazer-Jones D9 expansion shell assembly. [0008] Another example includes unraveling the cable and sliding a ring over and down along the center or king wire of the cable to a desired location and then rewinding the cable. In this way, a bulge or ‘bird cage’ is formed in the cable due to a spreading of the wires in the area of the ring. The bulge or spreading of the wires permits resin used with the cable to permeate into the cable to enhance anchorage of the cable upon the setting of the resin. If mechanical anchorage is also desired, an additional thread-bearing or thread-like-bearing apparatus must still be added if a desired bolt or Frazer-Jones D9 expansion shell assembly is to be used. [0009] A number of devices rely upon a thread-bearing sleeve being disposed about the cable or other threaded systems to tension a cable. The sleeve is positioned relative to the cable or other threaded systems which are used to tension the cable including: [0010] (1) placing a threaded tube and clamping it on the cable; [0011] (2) threading the cable itself; [0012] (3) placing and securing the cable inside a threaded bar such as a DYWIDAG threadbar® with a hole in it; and [0013] (4) using a threaded insert which is placed over the king wire and then threaded inside a Frazer-Jones D9 expansion shell assembly. [0014] A number of cable and other bolt assemblies are known, including those taught by U.S. Pat. Nos. 2,667,037, 3,077,809, 4,509,889, 4,954,017, 4,984,937, 5,015,125, 5,026,517, 5,215,411, 5,230,589, 5,259,703, 5,375,946, 5,378,087, 5,441,372, 5,458,442, 5,525,013 and others. [0015] These techniques include drilling a long hole into the earthen geology which is to be stabilized. A requisite amount of multi-component epoxy resin is placed in the hole at the desired location. The steel cable is also placed in the hole. A machine is used to spin the cable thereby mixing the multi-component epoxy to cause the chemical reaction between the multi-components. The epoxy sets and anchors the cable in the hole. [0016] Known techniques for mixing multi-component epoxy include mechanical devices designed to spin the cable at a relatively low torque to mix the epoxy components followed by tensioning the cable using increased torque after the cable is cemented in place. The mechanical devices include known and available domed nuts, crimped bolts, perpendicular roll pins, shear pins, weld beads, and keys ways which permit spinning a nut or other structure on a threaded sleeve at a low torque without compromising or defeating the ability of the domed nuts, crimped bolts, perpendicular roll pins, shear pins, weld beads, and keys ways to at least temporarily fix the relative position of the nut and threaded sleeve affixed to the cable. In this way, the spinning of the cable mixes the epoxy resin components. After the cable is cemented in place, a higher torque is then applied, typically in the same direction as the low torque, to tension the cable which use of higher torque does compromise or defeat the ability of the domed nuts, crimped bolts, perpendicular roll pins, shear pins, weld beads, and keys ways to fix the relative position of the nut and threaded sleeve. [0017] When tensioning a steel cable, it is not uncommon for the cable itself to twist somewhat between the point of application of torque for tensioning and the point at which the cable is cemented in place. This can cause a slight decrease in the length of the cable. Upon release of the torquing device the cable can untwist thereby returning to its longer repose length and causing an undesirable decrease in the tension on the cable. [0018] Accordingly, it would be an improvement in the art to augment or even replace current techniques with simpler devices and devices which permit the use of power tools which apply torque in opposing directions and avoid unwanted decrease in tensioning of the cable after removal of the torquing tool. SUMMARY OF THE INVENTION [0019] The present invention relates to an integral wedge barrel and threaded sleeve which can be used for both spinning to mix epoxy resin and used to tension a cable bolt. [0020] The present invention contemplates a unitary or integral wedge barrel and threaded sleeve with a rotatable nut about the threaded sleeve. The threaded sleeve is disposed in an aperture of a bearing plate. A cable is disposed through the threaded sleeve and through the wedge barrel. The cable is fixed in place relative to the wedge barrel by common barrel wedges. When assembled the cable is fixed relative to the wedge barrel. The threaded sleeve is fixed relative to the barrel because the threaded sleeve and wedge barrel are either manufactured as one integral unit or are joined together in a fixed relationship by means of welding or some other common joining practice. [0021] In use, the device permits reliable mixing of epoxy resin components by rotating the nut until it abuts the wedge barrel whereupon the cable will spin in the direction the nut is being turned. This turning or spinning action can be used to mix the epoxy resins. [0022] In some applications, after the epoxy resin is set and the cable cemented in place, the nut may be turned or spun in the opposite direction causing the nut to move away from the wedge barrel and move toward the opposing bearing plate against which the nut can be forced by applying high torque to the nut whereby the cable is put under tension. In other applications it may be necessary to use known techniques thereby turning the cable in the same direction for both mixing and tensioning. [0023] The bearing plate may comprise one or more projections or protrusions from the face or edge of the bearing place toward the surface against which the bearing place is disposed. This provides points of contacts between the bearing plate and for example an earthen or rock surface to reduce or prevent the bearing place resting against a surface from spinning when the cable is being tensioned. [0024] The structure of the aperture of the bearing plate and the threaded sleeve disposed in the aperture permit the threaded sleeve to slide through the bearing plate to permit tensioning while at the same time reducing or preventing any twisting of the cable-bearing threaded sleeve within the aperture. [0025] While the methods and processes of the present invention have proven to be particularly useful in the area of cable bolt tensioning, those skilled in the art can appreciate that the methods and processes can be used in a variety of different applications and in a variety of different areas of manufacture to yield an equivalent device. [0026] These and other features and advantages of the present invention will be set forth or will become more fully apparent in the description that follows and in the appended claims. The features and advantages may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Furthermore, the features and advantages of the invention may be learned by the practice of the invention or will be obvious from the description, as set forth hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS [0027] In order that the manner in which the above recited and other features and advantages of the present invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that the drawings depict only typical embodiments of the present invention and are not, therefore, to be considered as limiting the scope of the invention, the present invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: [0028] FIG. 1 illustrates a perspective view of one embodiment of the device and system that provides a suitable structure and function for the present invention; [0029] FIG. 2 illustrates a cross-sectional view of an embodiment of the present invention; [0030] FIG. 3 illustrates a cross-sectional view of an embodiment of the present invention; [0031] FIG. 4 illustrates use of the present invention with a breakaway view of a cable cemented into a geological formation. [0032] FIG. 5 illustrates a perspective view of another embodiment of the bearing plate; [0033] FIG. 6 illustrates a perspective view of another embodiment of the a threaded sleeve with at least one flatten side; [0034] FIG. 7 illustrates a cross-sectional view of another embodiment; [0035] FIG. 8 illustrates a cross-sectional view of another embodiment; [0036] FIG. 9A illustrates a partial cross-sectional view along line A of FIG. 8 depicting the relationship between a bearing plate and a threaded sleeve; [0037] FIGS. 9B , 9 C and 9 D illustrate partial cross-sectional views of alternative embodiments of FIG. 9A ; [0038] FIG. 10 illustrates use of another embodiment of the present invention with a breakaway view of a cable cemented into a geological formation. DETAILED DESCRIPTION OF THE INVENTION [0039] The present invention relates to a device for use in anchoring and tensioning cables or cable bolts to stabilize walls or ceilings in earthen bodies such a mines or other underground openings. In particular, the present invention is directed to a integral device which both facilitates mixing the epoxy resins used to anchor the cable bolt in the earthen body and tensioning the cable bolt after it is anchored in place. The present invention contemplates an integral wedge barrel used to capture a cable bolt and a threaded sleeve about the cable bolt. [0040] FIG. 1 and the corresponding discussion are intended to provide a general description of one embodiment of the present invention. One skilled in the art will appreciate that the invention may be practiced by one or more embodiments in a variety of configurations. Mixing and tensioning assembly 10 is shown in perspective view. Assembly 10 comprises cable or cable bolt 20 , an integral body 30 of a wedge barrel and threaded sleeve disposed about cable bolt 20 , nut 40 disposed along integral body 30 and bearing plate 50 . Cable bolt 20 , nut 40 and bearing plate 50 are all commonly known, used and available cable bolt components. [0041] As depicted in FIG. 2 , device or integral body 30 comprises a wedge barrel end 32 defining sloped interior surface 34 to receive a plurality of wedges 36 . Integral body 30 further comprises a threaded sleeve portion 38 . While the preferred embodiment contemplates integral body 30 being a continual unitary member, a person of skill in the art would recognize that other embodiments would contemplate an interface between a wedge barrel and a threaded sleeve achieved via a weld between a wedge barrel and a threaded sleeve, via a recessed barrel with a mating surface corresponding to a mating end of a threaded sleeve, via screwing the threaded sleeve into the wedge barrel, or via prongs on one end of the threaded sleeve engaging apertures in the wedge barrel, all to fix the interrelationship between the wedge barrel and the threaded sleeve. The result in all embodiments being a interdependent wedge barrel and threaded sleeve which when either part is acted upon by a force the same or substantially similar force is also transmitted to the other part of the integral body 30 . [0042] Cable bolt 20 is disposed within integral body 30 . As is commonly known in the art, wedges 36 disposed between cable bolt 20 and wedge barrel 32 act by friction and/or other forces to fix cable bolt 20 within integral body 30 such that force along bolt 20 is transmitted to integral member 30 and vice versa. [0043] Nut 40 is disposed along a length of body 30 between wedge barrel portion 32 and bearing plate 50 . Nut 40 can be turned in both directions. As shown in FIG. 2 , when nut 40 is turned until it abuts wedge barrel 32 , then upon abutting wedge barrel portion 32 , further turning of nut 40 will cause both body 30 and bolt 20 to turn or spin in the same direction. This spinning can be used to spin cable bolt 20 to mix epoxy resins as discussed below. [0044] As shown in FIG. 3 , nut 40 can also be turned in the opposite direction until it abuts bearing plate 50 , or one or more optional washers 60 constructed of metal and/or HDEP, Teflon, nylon, or similar materials to reduce friction. As known in the art, plate 50 may be dome-shaped. Bearing plate 50 defines a plate aperture 52 to permit plate 50 to move independent of body 30 . Similarly, optional washer 60 defines a washer aperture 62 to permit washer 60 to move independent of body 30 . Upon abutting plate 50 or washer 60 , continued turning or spinning of nut 40 in the same direction puts a force upon plate 50 thereby putting cable bolt 20 in tension as plate 50 is forced against a geologic formation such as rock, dirt or mineral. It will be appreciated that threaded sleeve portion 38 is of a sufficient length to permit tensioning and, as needed, retensioning of cable bolt 20 . Threaded sleeve portion 38 may be about twelve inches or longer or shorter depending on the geologic conditions of use. [0045] The present invention permits universal use of assembly 10 . For example, when sleeve threads are right-handed threads as is typical in coal mines, tools are used that are able to turn nut 40 in either direction as depicted in FIGS. 2 and 3 . [0046] When sleeve threads are left-handed threads as is typical in hard rock mines, jack-legs are typical tools used to turn nuts 40 but are able to turn nut 40 in only one direction to force nuts 40 against bearing plates 50 . When tools such as unidirection jack-legs are used, the present invention further comprises means for providing a temporary, fixed interface between nut 40 and threaded sleeve portion 38 . The temporary, fixed interface between nut 40 and threaded sleeve portion 38 can be accomplished by known techniques previously discussed including but not limited to known frictional interfaces, weld beads, roll pins, keyway with keys, buggered threads, domed nuts, or crimped sleeves. As a result, turning of nut 40 also turns sleeve portion 38 which turns cable 20 . This commonly known unidirection turning of nut 40 can be used to both mix epoxy resins at a lower torque and then at higher torque to overcome, break or shear the temporary, fixed interface to place bolt 20 under tension. [0047] An optional sleeve cover, not shown, extends along the length of threaded portion 39 from nut 40 through plate aperture 52 towards the end of portion 38 to protect the threads of portion 38 from being damaged or compromised prior to use. The sleeve cover is disposed about threaded portion 38 and can comprise plastic, soft metal, rubber, cardboard or any other suitable material capable of protecting the threads of sleeve portion 38 from damage prior to use. [0048] Embodiments of the present invention may comprise other structural features. Bearing plate 50 may comprise one or more projections or protrusion toward the bearing surface. For example, FIGS. 5 and 7 depict projections 54 which may imbed into or catch onto the bearing surface or onto or into appliances such as metal mesh upon a bearing surface. In place, projections 54 reduce or prevent bearing plate 50 from spinning when torque is applied to tension the cable. As depicted in FIG. 8 , alternative projections or protrusions 56 may be employed. Projections 56 could be prepared by casting, machining or by adding material to plate 50 such as by welding. FIG. 8 also depicts other alternative projections 57 which may be formed by a punching or stamping process during manufacture of plate 50 . In all cases, projections 54 , 56 or 57 act to engage the surface or surfaces against which bearing plate 50 is positioned to reduce or prevent movement or spinning of plate 50 . [0049] Threaded member 38 may comprise one or more exterior shapes with a corresponding, opposing and mating shape in the aperture 52 of bearing plate 50 , all designed to permit threaded member 38 to slide through aperture 52 of plate 50 but also reduce or prevent threaded member 38 from spinning within aperture 52 . For example, FIG. 6 depicts threaded member 38 with flattened side 39 . FIG. 9A depicts a corresponding, opposing flattened aperture wall 58 of plate 50 which mates with surface 39 . FIG. 9B depicts another illustrative embodiment comprising threaded member 38 with two flattened side walls 39 within two corresponding, opposing flattened aperture walls 58 which mate with surfaces 39 . FIG. 9C depicts another illustrative embodiment comprising threaded member 38 with keyway 39 with a corresponding, opposing key projection 58 of plate 50 projecting into keyway 39 which mates with surface 39 . FIG. 9D depict another illustrative embodiment comprising an alternative threaded member 38 with keyway 39 with a corresponding, opposing key projection 58 of plate 50 projecting into keyway 39 which mates with surface 39 . These embodiments are merely illustrative of one or more opposing surfaces 39 and 58 which permit member 38 to pass through plate 50 but reduce or prevent member 38 from turning or spinning independent of member 38 's relationship to or position in plate 50 . One skilled in the art may recognize other such structures. The structure and function of embodiments illustrated in FIGS. 9A-D are examples of means for substantially preventing the rotation of threaded member 38 and cable 20 when disposed through plate 50 . [0050] The structure and function of embodiments illustrated in FIGS. 9A-D combined with projections 54 , 56 , or 57 are examples of means for substantially preventing the twisting of cable 20 during tensioning. That is, the means for substantially preventing the twisting of cable 20 during tensioning reduces or prevents the undesirable twisting, shortening and/or lengthening of cable 20 during or after tensioning. The present invention reduces or prevents back-spin of the cable after release from the torquing tool. These devices and techniques may also be used in certain mining operations that use cement grouting systems which require no mixing but utilize similar tensioning of a cable. [0051] As depicted in FIGS. 4 and 10 , the subject wall, roof, or floor of a geologic structure 70 is drilled to create drill hole 72 . Epoxy resin components are placed in hole 72 at the desired location. Assembly 10 , preassembled and comprising cable 20 , body 30 , nut 40 and bearing plate 50 is placed such that cable 20 is inserted into hole 72 to a depth so a portion of cable 20 is inserted through or adjacent the epoxy resin components in hole 72 . Nut 40 is turned in the desired direction causing cable 20 to spin in hole 72 to mix the epoxy components to create a epoxy resin or cement 80 which acts to anchor cable 20 in hole 72 . Cable 20 is thrust into hole 72 to the desired depth with the entire device 10 thrust against wall 70 and held in place until the resin sets. After the resin or cement is set and cable 20 is anchored in hole 72 , nut 40 is again turned in the desired direction to further force nut 40 against bearing plate 50 , or washer 60 . This pushes plate 50 against wall 70 putting cable 20 under tension. The appropriate tension is placed upon cable 20 to help stabilize wall 70 . After tensioning, the preferred installation contemplates removing the thrust force by withdrawing the tensioning tool about one quarter inch away from the washer 60 or plate 50 to ensure that the tool is not experiencing friction loss against the washer 60 or plate 50 and nut 40 is again turned for further tensioning. A plurality of assemblies 10 are used over an area to prevent geologic structures 70 from caving in and causing injury to persons or equipment. [0052] The devices depicted in FIGS. 5-10 provided the added advantage of having bearing plate 50 affirmatively engage wall 70 or any appliance thereon via projections 54 , 56 , or 57 to reduce or prevent movement of plate 50 vis-à-vis wall 70 . When torque is applied to tension cable 20 , member 38 may move laterally through plate 50 in the direction of the cable as needed for tensioning. However, because of surfaces 39 and 58 member 38 is not permitted to spin or rotate within aperture 52 of plate 50 . As a result, cable 20 is held in a relatively fixed orientation to wall 70 thereby reducing or preventing twisting of cable 20 between the point of application of torque for tensioning and the point of cementation or anchorage in wall 70 during or after tensioning. [0053] While the Figures only depict a single cable comprising a plurality of wound or twisted wires, the present invention also contemplates assembly 10 being capable of receiving and securing a number of cables 20 as illustrated in U.S. Pat. No. 5,525,013. [0054] Thus, as discussed herein, the embodiments of the present invention embrace an assembly 10 comprising a device which can be turned to facilitate both mixing resin or cement to anchor cable 20 and to put cable 20 under the desired tension to secure the adjacent surface. [0055] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.	The present invention is directed to a device and assembly for the anchoring and tensioning of cable bolts used in earthen formations to stabilize the earthen structures to prevent or minimize the caving in or sluffing-off of the earthen structure. The new invention presents an integral wedge barrel and threaded sleeve which can be turned to facilitate both the mixture of cementing resins and the physical tensioning of an anchored cable and which can reduce or prevent undesirable twisting of the cable during tensioning.	4
[0001] This application claims priority from U.S. Provisional Application Ser. No. 60/252,610, filed Nov. 22, 2000. BACKGROUND OF THE INVENTION [0002] The present invention relates to a bottom rail for a covering for an architectural opening such as Venetian blinds, pleated shades, and other blinds and shades. Typically, a blind transport system will have a top head rail which both supports the blind and hides the mechanisms used to raise and lower or open and close the blind. The raising and lowering is done by lift cords which support the bottom rail (or bottom slat). This bottom rail is normally heavier and larger in cross-section, or more rigid, than any of the slats that are intermediate between it and the head rail. The blind may be tilted in the forward direction and in the rear direction. The tilting is typically accomplished with ladder tapes (and/or tilt cables) which run along the front and back of the blind and are also attached to the bottom rail. By shortening one of the tilt cables relative to the other, the corresponding edge of the blind is lifted up, causing the blind to tilt upwardly in the direction of the shortened tilt cable and downwardly in the direction of the extended tilt cable. The lift cords (in contrast to the tilt cables) may run along the front and back of the stack of slats or through slits in the middle of the slats, and are connected to the bottom rail. [0003] In these constructions, the closure of the blinds (tilting closed) tends to become less effective toward the bottom of the blind. When the blind is fully lowered, all the weight has been lifted off of the lift cords and transferred to the ladder tapes containing the tilt cables. This enables the ladder tapes to have the maximum influence on tilting the bottom rail, which tends to maximize the closure at the bottom of the opening. However, even then, while the shortened cable adjacent to the edge of the blind which is tilted upwardly is under tension, the edge of the blind which is tilting downwardly is under no tension except what little tension gravity can afford, since the tilt cables can only function under tension, but not under compression (you cannot push on a rope). This gravitational influence on the downwardly tilting edge of the blind is partially offset by the ladder tapes, which take some of the weight of each slat away from the extended tilt cable and transfer it to the shortened tilt cable. Thus, the shortened tilt cables support more of the weight and, as a result, tend to stretch more, while the extended cables support less of the weight and thus tend to stretch less. This often results in incomplete closure of the blind. [0004] This situation is aggravated for a product in which the lift cords run along the front and back of the stack of slats. In this instance, when the blind is fully lowered, once again all the weight has been lifted off of the lift cords and transferred to the ladder tapes. However, as soon as the tilting action is started, the edge of the blind which is tilted upwardly is free to rise, but the opposite edge is not free to go downwardly, because, as soon as it starts to do so, it encounters interference from the lift cable. This stops the downward movement of that tilting edge, and the bottom rail stops pivoting around its center and instead begins to pivot about its now fixed, downwardly tilting edge, therefore lifting the center of gravity of this bottom rail and causing poor closure. Thus, in this type of product, the poor closure is due both to a lack of tension on the ladder tapes on the downwardly tilting edge of the bottom rail, and to the interference by the lift cords with the downward motion of the downwardly tilting edge. [0005] The Swedish Patent application SE 15427/64 (filed on Dec. 19, 1964) attempts to address this incomplete closure problem by installing a free rolling weight in the bottom rail. As the bottom rail is tilted, the free rolling weight shifts to one edge of the bottom rail, thus putting the extended tilt cable under increased tension caused by the shifting weight. However, this solution does nothing to alleviate the problem caused by the interference by the lift cords with the downward motion of the downwardly tilting edge in the situation where the lift cords run along the front and back of the stack of slats. SUMMARY OF THE INVENTION [0006] One example of an embodiment of the present invention provides a bottom rail with a shifting weight and lift cords which support the bottom rail while being free to move in the forward-to-rear direction relative to the bottom rail. In this arrangement, the shifting weight in the bottom rail moves to whatever edge is the downwardly tilting edge of the bottom rail and thus, by increasing the weight at that edge, aids in putting the extended tilt cables under tension, enhancing the closure of the blind. Furthermore, because the bottom rail is free to move in the front-to-back direction relative to the lift cords, the lift cords do not interfere with the tilting of the blind. Thus, the blind closes properly, even at the bottom. BRIEF DESCRIPTION OF THE DRAWINGS [0007] [0007]FIG. 1 is a partially broken away perspective view of a blind made in accordance with the present invention; [0008] [0008]FIG. 2 is a schematic broken away side view of a conventional prior art bottom rail when in the untilted position; [0009] [0009]FIG. 3 is a schematic broken away side view of the conventional prior art bottom rail of FIG. 2 but tilted closed in one direction; [0010] [0010]FIG. 4 is a schematic broken away side view of the conventional prior art bottom rail of FIG. 3 but tilted closed in the other direction; [0011] [0011]FIG. 5 is a schematic broken away side view of the shifting weight bottom rail of FIG. 1 when in the untilted position; [0012] [0012]FIG. 6 is a schematic broken away side view of the shifting weight bottom rail of FIG. 5 but tilted closed in one direction; [0013] [0013]FIG. 7 is a schematic broken away side view of the shifting weight bottom rail of FIG. 6 but tilted closed in the other direction; [0014] [0014]FIG. 8 is a perspective view of a tie off ring used to secure a lift cord to the rod of FIG. 1; [0015] [0015]FIG. 9 is a partially broken away perspective view of the bottom rail of FIG. 1 before the tie off ring is inserted through a slot at one edge; [0016] [0016]FIG. 10 is a schematic broken-away front view of the bottom rail of FIG. 1 showing the slot used to feed the tie off ring of FIG. 8 into the bottom rail; [0017] [0017]FIG. 11 is the same view as FIG. 9, except the tie off ring has been inserted through the slot of FIG. 10; [0018] [0018]FIG. 12 is the same view as FIG. 11, except the tie off ring has been rotated 90 degrees to align the hole in the ring in readiness to receive the rod; [0019] [0019]FIG. 13 is the same view as FIG. 12, except it shows the rod being inserted at one end of the bottom rail; [0020] [0020]FIG. 14 is the same view as FIG. 13, except it shows the rod threaded through the hole in the tie off ring inside the bottom rail; [0021] [0021]FIG. 15 is the same view as FIG. 14, except it shows the rod totally inserted within the bottom rail, and the ring insertion tab broken off from the tie off ring; [0022] [0022]FIG. 16 is the same view as FIG. 5, showing a schematic broken away side view of the shifting weight bottom rail of FIG. 1 when in the untilted position; [0023] [0023]FIG. 17 is similar to FIG. 16, but a plurality of individual balls is used as the shifting weight instead of using a rod; [0024] [0024]FIG. 18 is similar to FIG. 16, showing a schematic broken away side view of a shifting weight bottom rail when in the untilted position, but the bottom rail is a U-shaped open top bottom rail; [0025] [0025]FIG. 19 is similar to FIG. 18, showing a schematic broken away side view of the shifting weight bottom rail but using individual balls as a weight instead of a rod; [0026] [0026]FIG. 20 is similar to FIG. 16, showing a schematic broken away side view of a shifting weight bottom rail when in the untilted position, where the bottom rail is a U-shaped (open bottom) bottom rail with an optional cover; [0027] [0027]FIG. 21 is similar to FIG. 20, showing a schematic broken away side view of the shifting weight bottom rail but using individual balls as a weight instead of a rod; [0028] [0028]FIG. 22 is a view similar to the view of FIG. 5, but showing an embodiment in which the lift cord extends around the bottom of the bottom rail and is not fastened to the weight; and [0029] [0029]FIG. 23 is a view similar to the view of FIG. 5, but showing an embodiment in which the lift cord extends through an eyelet opening in the bottom rail and is not fastened to the weight. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0030] Referring now to FIG. 1, the blind 10 includes a head rail 12 , and a plurality of slats 14 suspended from the head rail 12 by means of tilt cables 18 and the associated cross cords 19 which together comprise the ladder tapes 21 . (The cross cords 19 are shown in FIGS. 5 - 7 .) Lift cords 16 extend through the head rail and along the front and back of the stack of slats, and are fastened at the bottom slat (or bottom rail) 20 , which is heavier and larger in cross-section, or more rigid, than the other slats 14 . Inside the head rail 12 there are one or more drives or mechanisms to raise and lower the lift cords 16 , in order to raise and lower the blind, and mechanisms to raise and lower the tilt cables 18 to tilt the blind open or closed, as is known in the art. [0031] [0031]FIG. 2 shows a typical prior art bottom rail 20 A. In this instance, both the lift cords 16 and the tilt cables 18 are fastened to the front and rear edges of the bottom rail 20 A. Since the lift cords 16 do not pass through holes in the slats 14 , there are no holes through which light can pass when the blind is closed, which is an advantage. However, as can be appreciated in FIGS. 3 and 4, as the blind is tilted closed, the downwardly tilting edge 22 A of the bottom rail 20 A is held up by the lift cord 16 , which has a fixed length from the head rail 12 to the edge of the bottom rail 20 A. Since this edge of the bottom rail 20 A is not allowed to drop, but the opposite edge of the bottom rail 20 A is being pulled up, the bottom rail 20 A begins to pivot around its downwardly tilting edge 22 A instead of pivoting around its center. This action tends to raise the center of gravity of the bottom rail 20 A, resulting in poor closure of the blind and an arcing of the bottom of the blind. [0032] [0032]FIGS. 5, 6, and 7 show one embodiment of a shifting weight bottom rail 20 made in accordance with the present invention. An elongated rod 24 , which acts as the shifting weight, is inserted lengthwise along the central portion of the hollow bottom rail 20 . The lift cords 16 pass through small slotted openings 26 (See FIGS. 10 and 11), which are present at both the front and rear edges of the bottom rail 20 , as will be explained in more detail later, and are attached to the rod 24 . The front and rear lift cords 16 may be directly opposite each other, essentially forming a continuous cord, or they may be longitudinally-spaced from each other. By extending through the slots 26 , the lift cords 16 extend below at least a portion of the bottom rail 20 , in order to support the weight of the bottom rail 20 . As the blind is tilted closed (See FIGS. 6 and 7), the lift cords 16 are brought closer together to each other. The lift cords 16 which are on the upwardly tilting edge of the bottom rail 20 are free to slide through the slotted openings 26 , allowing the rod 24 to fall toward the downwardly tilting edge 22 of the bottom rail 20 . As the rod 24 falls to the downwardly tilting edge 22 of the bottom rail 20 , it allows more lift cord 16 to feed out through the slotted openings 26 at the downwardly tilting edge 22 of the bottom rail 20 , effectively lengthening the lift cords 16 on the side of the bottom rail 20 adjacent to this downwardly tilting edge 22 of the bottom rail 20 . Thus, the bottom rail 20 is allowed to pivot around its center of gravity without being held up by the lift cords 16 , and the rod 24 provides an added weight to put increased tension on the ladder tapes 18 on the downwardly tilting edge 22 of the bottom rail 20 to result in a complete closure of the blind. [0033] [0033]FIG. 8 shows a tie off ring 28 when it is outside the bottom rail 20 . The tie off ring 28 may be used to secure the lift cord 16 to the weight 24 . The tie off ring 28 includes a head 29 having a substantially annular opening 30 with an inside surface that has a diameter and profile closely matching the outside of the rod 24 , so that the rod 24 can be fed through the annular opening 30 . A small slotted recess 32 extends from the annular opening 30 and is used to secure the lift cord 16 to the tie off ring 28 . In order to secure the lift cord 16 to the tie off ring 28 an enlargement (not shown) such as a knot is secured to the lift cord 16 , and then the lift cord 16 is slid through the slot 32 , with the enlargement trapped behind the slot 32 . Once the rod 24 is fed through the opening 30 of the tie off ring 28 , the lift cord 16 will be secured to the tie off ring 28 , since the enlargement on the cord 16 will not allow the lift cord 16 to be pulled out. The tie off ring 28 also has a handle 34 which has a narrow neck 36 at the point where the handle 34 joins with the head 29 . The neck 36 is a weak link, designed to break away in order to readily separate the head 29 from the handle 34 . [0034] [0034]FIG. 9 shows the tie off ring 28 with the lift cord 16 attached to it just as it is readied to be inserted into the bottom rail 20 via one of the slotted openings 26 on the front edge of the rail 20 . The thickness of the head 29 of the tie off ring 28 is relatively small in relation to its diameter, so that it may be inserted into the bottom rail 20 using a slender slotted opening 26 (See FIG. 10) in the edge of the bottom rail 20 . The dimensions of the slender slotted opening 26 are such that it is just slightly wider than the thickness of the head 29 and it is just lightly longer than the diameter of the head 29 . The slotted openings 26 are oriented with the long direction in line with the longitudinal axis of the bottom rail 20 and centered vertically in the edge of the bottom rail 20 because this minimizes the adverse effect on the strength of the bottom rail 20 by making such slotted openings 26 . When the bottom rail 20 is in a vertical position, it has a very strong beam strength, but when it is in a horizontal position the beam strength is minimized. The slotted openings 26 preferably are located in its neutral web in order to minimize the impact on the beam strength. [0035] [0035]FIG. 11 shows the tie off ring 28 inserted into the bottom rail 20 , with the head 29 having passed through the slotted opening 26 , but the handle 34 still extending out of the slotted opening 26 at the front edge of the bottom rail 20 . The lift cord 16 , which is secured to the head 29 of the tie off ring 28 , is also extending out of the front edge of the bottom rail 20 through the slotted opening 26 . [0036] [0036]FIG. 12 shows the tie off ring 28 rotated 90 degrees, by rotating the handle 34 about its longitudinal axis. This is done to line up the annular opening 30 with the rod 24 which is inserted from one end of the bottom rail 20 as shown in FIG. 13. FIG. 14 shows the rod 24 after it has been inserted through the annular opening 30 of the tie off ring 28 . [0037] Once the tie off ring 28 is secure around the rod 24 , the handle 34 is twisted until it snaps off at the weakened point 36 . The handle 34 then is removed through the slotted opening 26 . The head 29 remains attached to the rod 24 , and the lift cord 16 remains attached to the head 29 (and thus now also attached to the rod 24 ). The lift cord 16 then extends out of the bottom rail 20 via the slotted opening 26 . This same process is repeated for as many lift cords 16 as are deemed necessary for a particular blind, and these lift cords may be attached from either edge of the bottom rail 20 , either the front edge facing the room or the rear edge facing the wall. End caps (not shown) may be installed at the ends of the bottom rail to hide and confine the rod 24 within the bottom rail 20 . After the ladder tapes 18 are connected to the edges of the bottom rail 20 , the assembly is ready to operate in the manner which was described earlier. As the blind is tilted closed, the bottom rail 20 pivots around its center of gravity. The bottom rail 20 is not impeded by the lift cords 16 , since the lift cords 16 are freely movable in the front-to-rear direction relative to the bottom rail and move with the weight 24 . The rod 24 provides an added weight to put increased tension on the ladder tapes 18 on the downwardly tilting edge 22 of the bottom rail 20 to result in a complete closure of the blind as shown in FIGS. 6 and 7. When the blind is tilted open, the action is reversed. The bottom rail 20 once again pivots around its center of gravity, and the rod 24 moves to a position midway between the two edges of the bottom rail 20 as shown in FIG. 5. ALTERNATE EMBODIMENTS [0038] [0038]FIG. 16 depicts the first embodiment of the present invention, with a rod 24 inserted longitudinally inside the bottom rail 20 , and the lift cords 16 attached to the rod 24 by means of the tie-off ring 28 , as already described above. FIG. 17 depicts the same bottom rail 20 but, in this instance, the shifting bottom weight is made up of a plurality of discrete short rods or spheres 24 A. Thus, at each location where lift cords 16 enter the bottom rail 20 , a single short rod or sphere 24 A may be placed, and the lift cords 16 are secured to these short rods or spheres 24 A. These short rods or spheres 24 A will likely be of larger diameter than the single rod 24 of the preferred embodiment in order to have sufficient weight to aid in the proper closing of the blind 10 . [0039] Since the previously described means for tying off the lift cords 16 to the rod 24 using the tie-off ring 28 will not work for individual spheres 24 A, an alternate method for tying the lift cords 16 is employed. If the bottom rail 20 is a “one-piece”, enclosed design, as in FIG. 17 (this one-piece design does not count the optional end caps at the ends of the bottom rail 20 as additional pieces), then the lift cords 16 may be “fished” through to the end caps of the bottom rail 20 , where they are secured to the spheres 24 A before being inserted back into the bottom rail 20 . Alternately, the spheres 24 A may be modified so that a tie-off hook (instead of the tie-off ring 28 ) may be latched onto the sphere 24 A through an opening in the bottom rail 20 . [0040] Other solutions to the problem of tying off the lift cords 16 to the rod 24 or to the spheres 24 A are offered in FIGS. 18 - 21 . FIG. 18 depicts a “one-piece” hollow bottom rail 20 A which is a U-shaped “open top” bottom rail. Using this open top bottom rail 20 A eliminates the need for using the tie-off ring 28 , since the bottom rail 20 A is now open, and thus the rod 24 or spheres 24 A (See FIG. 19) are readily accessible for securing the lift cords 16 to them. FIG. 20 depicts a “one-piece” hollow bottom rail 20 B which is U-shaped and is open on the bottom (instead of on the top as was the case in FIGS. 18 and 19 with bottom rail 20 A). This new “open bottom” bottom rail 20 B offers the same accessibility for securing the single rod 24 or plurality of individual weight elements 24 A to the lift cords 16 without the need for the tie-off ring 28 . An optional cover 20 C (See FIGS. 20 and 21) may be snapped onto the rail 20 B in order to enclose the bottom rail so that it resembles the one-piece, enclosed design bottom rail 20 of the first embodiment while still allowing easy accessibility to its interior space. FIG. 21 shows the same arrangement as FIG. 20 but using a plurality of individual weight elements 24 A instead of the rod 24 . [0041] [0041]FIG. 22 shows an alternate embodiment, in which the lift cords 16 extend around the bottom of the bottom rail 20 in order to support the bottom rail 20 while permitting freedom of movement of the lift cords 16 relative to the bottom rail 20 . In this embodiment, the rod 24 moves freely in the bottom rail 20 as the tilt cables 18 tilt the blind. The lift cords 16 in this embodiment are not secured to the weight 24 . [0042] [0042]FIG. 23 shows another alternate embodiment, in which the lift cords 16 extend through respective openings in eyelets 25 , which project upwardly from the top surface of the hollow bottom rail 20 D. The lift cords 16 thus extend below a portion of the bottom rail 20 D in order to support the weight of the bottom rail 20 D, while being freely movable relative to the bottom rail in the front-to-rear direction. The weight 24 is freely movable within the rail 20 D and is not secured to the lift cords 16 . [0043] The embodiments described above are intended for illustration purposes only. They are not intended to show every possible embodiment of the present invention but rather are intended to show some illustrative examples of the present invention. It will be obvious to those skilled in the art that modifications may be made to the embodiments described above without departing from the scope of the present invention.	A covering for an architectural opening is made for better closure, especially adjacent to the bottom rail. A movable weight is mounted on the bottom rail, so that the weight shifts to the lower side of the bottom rail when the bottom rail is tilted. A lift cord is mounted to support the bottom rail while being freely movable relative to the bottom rail at least in the front-to-back direction. The weight helps shift the bottom rail into the desired position, and, by being freely movable in the front-to-back direction, the lift cord does not interfere with the motion of the bottom rail.	4
CROSS-REFEREENCE TO RELATED APPLICATIONS This patent application claims priority to provisional patent application 61/339,999 filed on Mar. 11, 2010 which is incorporated by reference herein. FIELD OF THE INVENTION The engine disclosed herein operates using accelerated compression ignition in the range from volumetric compression ratio of 20 and above, without knock or associated high NO x production. This engine is applicable to a wide range of fuels. BACKGROUND OF THE INVENTION This patent application claims priority to provisional patent application 61/339,999 filed on Mar. 11, 2010 which is incorporated by reference herein. There are many different engine cycles based on a piston/cylinder configuration. Each such engine is designed for a specific application. They differ widely in mode of operation, maximum size, engine speed, power output per unit mass, most suitable fuel and method of ignition. Engine fuel efficiency increases with: 1) compression ratio (CR) used; 2) ignition timing control; and 3) fuel combustion rate. A high rate of combustion maximizes combustion compression and minimizes piston ring and valve seat leakage. Many gasoline fueled piston engines are only able to ignite near stoichiometric mixtures and then at limited compression ratio. For decades automotive engineers have made improvements in Diesel fuel injected engines, Homogeneous Charge Spark Ignited Engines, and Homogeneous Charge Compression Ignition (HCCI) engines. HCCI technology eliminates the need for spark plugs and high pressure fuel injectors. However, ignition timing control has been successfully accomplished only over a narrow range in engine speed and load, and this only with the aid of complex computer control over the air/fuel mixture, exhaust gas recirculation (EGR), engine load, and engine speed. In 2009, Ford Motor Company and Mercedes Benz both incorporated a limited utilization of HCCI in their gasoline fueled automotive fleet which resulted in increased combustion rate and thus combustion compression, to improve fuel efficiency. Those computer controlled engines are able to take advantage of HCCI high combustion compression over a limited range of engine speed and power settings. Recently, new accelerated compression cranking mechanisms have become available, which are capable of producing rapid piston movement near top dead center (TDC). This increases the rate of compression to auto-ignition, to reduce heat loss to the walls and the likelihood of engine knock. Stratifying the charge has been found to be effective but, unfortunately, has been difficult to accomplish at all loads. Accelerated compression ignition can be accomplished even without air inlet throttle valve, and ignite mixtures near TDC under various engine speeds and loads, as required for maximum combustion compression. High compression ratio enables rapid combustion of lean mixtures as needed to limit NO x formation, but this requires high work and torque input during compression to a high compression ratio. It is well known that reducing the combustion volume and flattening the geometry of the combustion chamber during compression ignition significantly reduces the number of independent ignition centers which lead to engine knock and also minimizes the combustion volume and likelihood of engine knock. This invention avoids a complex cranking mechanism. It requires only a conventional reciprocating engine, with near sinusoidal piston motion. In one embodiment, upper cylinder wall cavities are made by machining a shallow tapered groove, beyond the cylinder wall and connecting this groove by multiple ports to the cylinder inside. In one embodiment, those cavities are sized to equal about half the clearance volume above the piston, at the time the upper two piston rings seal off those wall cavities. The result is doubling the compression ratio from 10:1 to 20:1 when piston reached TDC. This results in timed compression ignition as needed for HCCI use. The air/fuel mixture sealed off inside those cavities is ignited when the piston enters its expansion stroke and exposes those cavities. The slope of the cavity groove facilitates cleaning when the head is removed. SUMMARY OF THE INVENTION Slowly burning air-fuel mixtures in the Otto cycle is caused by low compression temperature, low spark energy, even when a near stoichiometric mixture is used. Slow fuel burning in a Diesel cycle is due to time required for fuel injection, droplet vaporization and mixing with air. Complex engines, including those with accelerated cranking mechanisms, are capable of controlling ignition timing in HCCI mixtures. But their mechanical complexity, high cost and limited engine speed prevents widespread usage. This invention requires only a simple and entirely mechanically control over ignition timing. It is based on a two-stage-compression process, with about half the air-fuel mixture being compression-ignited when the piston reached TDC. Soon after expansion the remaining air fuel mixture is ignited by the combustion products when the upper piston opens the cylinder wall cavities. As compression is doubled near TDC, the compression work and torque required are no more than that needed to reach half the final compression ratio. It is exactly this feature of this invention, which control compression ignition timing, at any engine speeds and load and is the reason that knock is avoided. Soon after TDC, during the power stroke, the upper piston ring opens the cylinder wall cavities to allow rapid ignition of remaining air-fuel mixture, by the now available combustion products. The advantage of using compression ignition energy near TDC is the ability to ignite very lean air-fuel mixtures. This reduces NOx formation and eliminates the need for an air intake throttle valve. However, near idle speed, a throttle valve may still be needed to slow the engine speed. The advantage of using a fuel injector, in one embodiment, is that it enables enriching only that small amount of charge, involved in compression ignition, while not affecting the combustible mixture which is temporarily sealed inside the cylinder wall cavities, thereby providing charge stratification with a conventional steady flow injector. The cylinder wall cavities make a non-sinusoidal relationship possible between compression ratio and crank-angle, with second stage (or greater number of stages) compression/ignition possible. The sinusoidal relationship between compression ratio and crank angle in a conventional diesel engine with CR =20 to 30, peaks at 19° BTDC, with a required torque 187% to 270% higher than for a spark ignition engine at CR=10. Such high cranking torque makes it difficult to warm-up a diesel engine by cranking, unless a valve lifter is used. The high torque associated with cranking/starting a Diesel engine requires the engine to be much stronger and heavier than a spark ignition engine or the cylinder wall cavity engine claimed herein. Cranking torque required during near sinusoidal compression of a CR=10 spark ignition engine is similar to that of the herein claimed second stage compression ignition engine operating at CR 20. Thus, structure and weight will be about the same as a conventional spark ignition engine. Without need for a Diesel type fuel injector, this cycle can be scaled down to a fraction of a cubic inch displacement, for use in UAV's, chain saws, lawnmowers, string trimmers, etc. Current small two-cycle engines have both inlet and exhaust ports located near the bottom of the piston stroke, and therefore, often use a domed piston to improve scavenging. However, when using cylinder wall cavities as in this invention, an exhaust valve can be added inside the cylinder wall cavity in one embodiment, as shown in FIG. 2 , to provide unidirectional scavenging while using a flat piston. In four-cycle applications, the narrow piston to head clearance may delay intake valve opening. The herein claimed engine configuration with cylinder wall cavities requires fewer parts than a spark ignition engine, has no need for spark plugs in at least one embodiment, can be operated on various fuels with lean mixtures to minimize NO x , and if used with Diesel fuel, may require some pre-heating of the combustible mixture, It extends engine life and miles per gallon due to the high lubricity and the heating value of diesel fuel. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-section of a four-cycle (four stroke cycle) engine designed for operation as described herein. FIG. 2 is a schematic cross-section of a two-cycle (two stroke cycle) engine designed for operation as described herein. FIG. 3 is a graphical presentation of how the Compression Ratio (CR) increases during the compression stroke in the final 60 degrees of crank angle before TDC. FIG. 4 is a graphical presentation of how the Compression Torque (CT) varies during the compression stroke in the final 60 degrees of crank angle before TDC. FIG. 5 is a graphical presentation of how the required Compression Work WC in N−m, increases during the compression stroke in the final 60 degrees of crank angle before TDC. FIG. 6 is a graphical presentation of how the temperature in degree K increases during the compression stroke in the final 60 degrees of crank angle before TDC. DETAILED DESCRIPTION The configurations in the description and drawings in no way are meant to limit the physical configuration of the possible embodiments of internal combustion engines that may operate as described herein. A spreadsheet calculation was used to quantify and graph typical compression performance parameters of a 500 cc displacement engine, operating on four different ideal cycles listed below. 1) Otto spark ignition at compression ratio CR=10, 2) Diesel compression ignition at CR=20 3) ACIE-20/12 is an abbreviation for: Accelerated Compression Ignition Engine in a spreadsheet with CR=20 at TDC and cylinder wall cavities closing at 12° before TDC. 4) ACIE-20/18 an abbreviation for: Engine with Cylinder-Wall-Cavities (CWC) in a spreadsheet with CR=20 at TDC and cylinder wall cavities closing at 18° before TDC. A spreadsheet calculation was used to calculate and graph the ideal performance during the compression stroke of four cycles shown in FIG. 3 though FIG. 6 . It assumed operation with a homogeneous mixture of regular gasoline and air, where an ideal spark ignition Otto cycle is limited to operation with a compression ratio CR=10 and air inlet temperature T at bottom dead center (BDC) equals 300 degree Kelvin and pressure p=100,000 Pa. Those numbers were used to be able to compare important parameters like: required cranking torque and work done in units of N−m. The following non-limiting example cylinder and stroke dimensions were used for those calculations: Piston stroke=10 cm, with an infinitely long piston connecting rod. Piston area=50 square cm. This correlates to a piston displacement of 0.5 liter. For ACIE-20/12, cylinder wall cavities volume was made 0.09 times piston displacement. Minimum above piston clearance volume was made 0.0107 times piston displacement. For ACIE-20/18, cylinder wall cavities volume was made 0.0946 times piston displacement Minimum above piston clearance volume to piston displacement ratio=0.0054 FIG. 1 is a schematic cross section of a four-cycle engine designed for operation in the herein claimed cycle. Thickened cylinder wall 10 is needed to install insulated cylinder wall cavities 12 . For adjustment of the cavity volume, externally accessible cavity volume adjustment bolts 14 can be used in one embodiment. Adjustment of volume adjustment bolts 14 can be performed prior to engine operation or during engine operation. Due to the high compression ratio needed, the inlet and outlet valve clearance between the nearly flat cylinder head 36 and piston 30 at TDC is limited. Therefore exhaust valve 18 above piston 30 may have to delay opening until the piston clearance has increased sufficiently. Then it may be advantageous to add an additional exhaust valve 16 inside one or more of cavities 12 . A similar situation applies to intake valve 20 positioned above the piston 30 and optional intake valve 22 located inside cylinder wall cavity 12 . To minimize engine knock the clearance between the flat-top piston 30 , with rounded edges, and the nearly flat cylinder head 36 should be minimized. To minimize engine knock, compression ignition is induced to originate on the centerline of piston 30 . Therefore, a nearly hemispherical insulated cavity 24 is installed inside the middle of the nearly flat cylinder head 36 on the bottom of a removable plug 26 which can be used to provide transducer access to the combustible mixture for pressure monitoring, gas sampling or for spark ignition if desired in one embodiment. The upper piston ring 28 is shown with piston 30 in position to just close off cylinder wall cavities 12 during a compression stroke. The lower piston ring 29 seals the cylinder wall cavity 12 on the opposite side of the cavity opening in relation to the upper piston ring 28 . Intermediate piston rings may be positioned between the upper piston ring 28 and the lower piston ring 29 . The piston is shown in the bottom dead center position 32 with piston wrist pin 34 used to connect to the crankshaft connecting rod (not shown). A cylinder bounded by a cylinder wall and a nearly flat cylinder head 36 forming a cylinder volume of variable size is fitted with a moveable piston 30 within the cylinder. The piston 30 is fitted with at least an upper piston ring 28 and a lower piston ring 29 . At least one cylinder wall cavity 12 located within the cylinder wall, the cylinder wall cavity 12 is in pneumatic communication with the cylinder volume unless the cylinder wall cavity 12 is sealed by at least the upper piston ring 28 . First stage compression of a fuel-air mixture within the cylinder occurs as the compression stroke begins. A portion of a fuel and air mixture within the cylinder volume is captured within the cylinder wall cavity 12 as the piston 30 moves in the cylinder compressing the mixture whereby the captured portion of the mixture is sealed within the wall cavity and separated from the cylinder volume by at least the upper piston ring 28 . The piston 30 moves further in the compression stroke resulting in second stage, accelerated compression of the remaining mixture in the cylinder volume to a higher pressure than the captured mixture within the cylinder wall cavity 12 whereby ignition of the remaining mixture in the cylinder volume occurs at the higher pressure. The second stage compression is accelerated compared to the first stage compression since a portion of the cylinder volume is partitioned from the original cylinder volume when the cylinder wall cavity 12 is sealed by at least the upper piston ring 28 . The piston reverses direction after reaching top dead center and the captured mixture in the cylinder wall cavity 12 is ignited as the upper piston ring 28 unseals the cylinder wall cavity 12 thereby adding energy to expanding gas within the cylinder. It is noted that the term “upper piston ring” used herein refers to the piston ring most closely located to the surface of the piston which experiences combustion of the fuel/air mixture and the term “lower piston ring” used herein refers to the piston ring located the furthest from the upper piston ring. The terms “upper piston ring” and “lower piston ring” are not meant to teach directly or indirectly a preferential orientation of the engine or piston therein. FIG. 2 is a schematic cross-section of a two-cycle engine designed for operation in the herein claimed cycle. Thickened cylinder wall 110 is needed to install insulated cavities 112 . For adjustment of the cavity volume, externally accessible cavity volume adjustment bolts 114 can be used. Adjustment of volume adjustment bolts 114 can be performed prior to engine operation or during engine operation. Due to the high compression ratio needed, the inlet and outlet valve clearance between cylinder head and piston at TDC is limited. Therefore, exhaust valve 118 above piston may have to delay opening until the piston clearance has increased sufficiently. Then it may be advantageous to add an additional exhaust valve 116 inside one or more of cavities 112 . When the crank case compressed inlet air/fuel mixture enters through intake port 138 , with piston 132 at bottom dead center, cylinder scavenging is greatly improved using the now open exhaust valves 116 and 118 , by providing unidirectional scavenging. To minimize engine knock, the clearance between the flat top piston 130 , with rounded edges, and the near flat cylinder head 136 should be minimized. To minimize engine knock, compression ignition is induced to originate on the centerline of piston 130 . Therefore a nearly hemispherical insulated cavity 124 is installed inside the middle of the nearly flat cylinder head 136 on the bottom of a removable plug 126 which can be used to provide transducer access to the combustible mixture for pressure monitoring, gas sampling or for spark ignition if desired. Upper piston ring 128 is shown with piston 130 in position to just close off cylinder wall cavities 112 . The lower piston ring 129 seals the cylinder wall cavity 112 on the opposite side of the cavity opening in relation to the upper piston ring 128 . Intermediate piston rings may be positioned between the upper piston ring 128 and the lower piston ring 129 . The piston 130 is shown in the bottom dead center position by 132 with piston pin 134 used to connect to the crankshaft connecting rod (not shown). It is noted that the term “upper piston ring” used herein refers to the piston ring most closely located to the surface of the piston which experiences combustion of the fuel/air mixture and the term “lower piston ring” used herein refers to the piston ring located the furthest from the upper piston ring. The terms “upper piston ring” and “lower piston ring” are not meant to teach directly or indirectly a preferential orientation of the engine or piston therein. FIG. 3 is a graphical presentation of how the Compression Ratio (CR) increases during the compression stroke, in the final 60 degrees of crank angle before TDC. The line referring to each engine is identified by the nomenclature on each graph. The upper line refers to the diesel engine and the lower line to the spark ignition engine. The two lines in between belong to the ACIE engines. The upper of those two lines starts to rise at 18° BTDC and the lower of those lines starts to rise at 12° BTDC. This plot line configuration applies to all FIGS. 3-6 . FIG. 4 is a graphical presentation of how the required compression torque in N−m, increases during the compression stroke in the final 60 degrees of crank angle before TDC. FIG. 5 is a graphical presentation of how the required compression work in N−m, increases during the compression stroke in the final 60 degrees of crank angle before TDC. FIG. 6 is a graphical presentation of how the combustible mixture temperature increases during the compression stroke in the final 60 degrees of crank angle before TDC. It is understood that the ideal calculation results shown in FIGS. 3-6 are for illustration purposes for one specific engine size and geometry. The calculations and results are merely intended to demonstrate the benefits of the instant invention compared to conventional engines cycles and are in no way intended to limit the application of the teachings herein. The various embodiments described herein are merely descriptive of the present invention and are in no way intended to limit the scope of the invention. Modifications of the present invention will become obvious to those having skill in the art in light of the detailed description herein, and such modifications are intended to fall within the scope of the appended claims.	An internal combustion engine has cylinder wall cavities located near the top dead center stroke end to allow optimizing the compression ratio in first stage compression, as function of fuel octane number used. The volume of the cylinder wall cavities is designed to be adjustable, even when the engine is operating. Using a conventional piston motion, the second stage compression becomes accelerated as soon the upper piston ring seals-off the cylinder wall cavities. This is due to the sudden significant reduction in volume. During the power stroke, after the upper piston ring opens the cylinder wall cavities; their fuel content is ignited by second stage combustion products. Because the torque required during accelerated compression is no greater than during first stage compression, stresses in the crankshaft are no more than in conventional spark ignition engines. This allows small displacement engines to be of light weight and to be hand cranked.	5
BACKGROUND OF THE INVENTION [0001] The present invention relates generally to chewing gum compositions and methods for making same. More specifically, the present invention relates to plasticizers for chewing gums as well as gum bases and gums including same. [0002] Conventional chewing gums usually contain synthetic elastomers, resins, fats, waxes, minerals, emulsifiers, plasticizers and antioxidants as well as sweeteners and flavors. Each ingredient contributes a particular feature toward the overall properties of the chewing gums. Due to the chemical composition of conventional chewing gums, such gums are not suitable for ingestion by humans. More specifically, the synthetic elastomers used in conventional chewing gums are neither ingestible nor readily degradable. Conventional chewing gums must therefore be removed from the mouth and discarded after chewing. Typically, chewed gum is properly discarded by wrapping it in its wrapper or other substrate and disposing of same. [0003] Chewing gums that contain synthetic elastomers readily adhere to almost any dry surface, such as skin, wood, concrete, paper, and cloth. Once adhered to a surface, they can be difficult to remove and typically undergo a very slow degradation process. Therefore, improperly disposed of chewed gum can potentially raise environmental concerns. Therefore, an environmentally-friendly chewing gum, which is ingestible and/or easily removable/degradable, is highly desirable. [0004] Unlike the synthetic flexible elastomers used in conventional chewing gums, the pure forms of most ingestible polymers such as proteins and polysaccharides are rigid and not suitable as chewing elastomers without plasticizers. In the presence of large amounts of plasticizers, such as water, alcohol and glycerin or polyols, some proteins and polysaccharides can become elastic at body temperature. However, due to their polar structures, typical digestible polymers such as starches, albumins and globulins have a tendency to be dissolved or dispersed in the mouth quickly and thus cannot withstand prolonged chewing. Therefore, water-insoluble digestible polymers, such as prolamines and glutelins, both of which are proteins, may be selected for formulating environmentally-friendly chewing gums. [0005] Prolamines, which are water-insoluble proteins found in the seeds of cereals, have been used in some consumer applications. Prolamines have been considered for use in chewing gum products. Prolamines can be plasticized by agents such as propylene glycol, ethylene glycol, acetic acid, lactic acid, polypropylene glycol, polyethylene glycol, glycerol and ethanol. The difficulty with such plasticizers, however, is that they are water-soluble, resulting in a proteinaceous gum product that cannot withstand a long period of chewing when compared to conventional chewing gums. [0006] Zein is a water insoluble prolamine obtained from corn gluten. Zein is a nutritious and readily biodegradable substance. Zein has been discussed as a potential chewing gum material. See for example U.S. Pat. Nos. 2,154,482; 2,489,147; 4,474,749; 4,931,295; 5,112,625; 5,164,210; 5,482,722; 5,882,702; 6,020,008 and non-U.S. Patents and Published Applications JP07163300, JP02211828, JP04079846, and JP06133735. Common plasticizers for zein include water, aqueous ethanol, glycerin, and polyols, but again, such water-soluble substances do not result in gums that provide adequate chew times. [0007] Despite ongoing research involving corn protein plasticizing agents suitable for the production of chewing gums, the chemical interactions between corn proteins and potential plasticizers are still not clearly understood. Selection of an effective plasticizer for corn protein therefore remains a challenging task. SUMMARY OF THE INVENTION [0008] The present invention relates to improved plasticizers and methods of selecting plasticizers to be incorporated into chewing gums. The present invention further provides improved chewing gum bases and finished chewing gum products as well as improved methods for making same. [0009] To this end, the present invention provides, in an embodiment, a method for selecting a plasticizer for corn proteins for the purpose of forming chewing gum comprising the steps of calculating the ratio of electron acceptors to the total number of carbon atoms (EA/C) of a plasticizer, calculating the ratio of electron donors to the total number of carbon atoms (ED/C) of the plasticizer, and selecting the plasticizer based on the EA/C and ED/C ratios. [0010] In an embodiment, the preferred EA/C is in the range of approximately 0.05 to about 1.5, and the ED/C is in the range of approximately 0.05 to about 2.0. [0011] In an embodiment, the EA/C is approximately 0.08 to about 1.0 and the ED/C is approximately 0.1 to about 1.1. [0012] In an embodiment, the corn protein to be plasticized is at least one selected from the group consisting of α-zein, β-zein, γ-zein, δ-zein, glutelins, other corn proteins, and combinations thereof. [0013] In an embodiment, the plasticizer comprises at least one electron acceptor and at least one electron donor. [0014] In an embodiment, the plasticizer is a single component that comprises at least one electron acceptor and at least one electron donor. [0015] In an embodiment, the plasticizer comprises a mixture of two or more components such that the mixture possesses at least one electron acceptor and at least one electron donor. [0016] In an embodiment, the electron acceptors are selected from the group consisting of hydrogen from hydroxyl, carboxylic acid, amino, imine, sulfhydryl, and aldehyde functional groups and combinations thereof. [0017] In an embodiment, the electron donors are selected from the group consisting of oxygen, sulfur, and nitrogen in hydroxyl, carbonyl, ether, amino, imine and sulfhydryl functional groups, and non-conjugated carbon-carbon double bonds and combinations thereof. [0018] In an embodiment, the plasticizer is selected from the group consisting of hydroxyl acids/hydroxyl acid esters/polyhydroxy acids including dibutyl tartrate, dipropyl tartrate, diethyl tartrate, ethyl lactate, propyl lactate, butyl lactate, malic acid, hydroxybutyric acid, glycolic acid, malic acid dibutylester, malic acid dipropylester, malic acid diethylester, hydroxybutyric acid butylester, hydroxybutyric acid propylester, hydroxybutyric acid ethylester, glycolic acid butylester, glycolic acid propylester, glycolic acid ethylester, polylactic acids, polyhydroxybutyric acid, polyglycolic acid or hydroxyl acid copolymers, mono-/di-glycerides, organic acid consisting of propanoic acid, butyric acid, oleic acid, linoleic acid, linolenic acid, abietic acid, dihydroabietic acid, dehydroabietic acid, rosin, butyl citrate, ethyl citrate, and combinations thereof. [0019] In a further embodiment, the present invention provides for a method of producing a gum base comprising the steps of combining a corn protein and a plasticizer. The plasticizer is selected by calculating the EA/C of the plasticizer, calculating the ED/C of the plasticizer, and selecting the plasticizer whose EA/C is in the range of approximately 0.05 to about 1.5, and whose ED/C is in the range of approximately 0.05 to about 2.0. [0020] In an embodiment, the temperature during the gum base-making process is in the range of approximately 20 to about 80° C. [0021] In a further embodiment, the present invention provides for a chewing gum base that comprises corn protein and a plasticizer. The plasticizer is selected by calculating the EA/C of the plasticizer, calculating the ED/C of the plasticizer, and selecting the plasticizer whose EA/C is in the range of approximately 0.05 to about 1.5, and whose ED/C is in the range of approximately 0.05 to about 2.0. [0022] In an embodiment, the gum base can have a corn protein content of approximately 10 to about 90%, preferably approximately 20 to about 70%, and most preferably approximately 30 to about 60% by weight based on the total weight of the base. [0023] In an embodiment, the gum base can have a plasticizer content of approximately 5 to about 50%, preferably approximately 10 to about 40%, and most preferably approximately 20 to about 30% by weight based on the total weight of the base. [0024] In an embodiment, the gum base further comprises at least one component selected from the group consisting of protein/protein hydrolysate and polysaccharide and combinations thereof [0025] In an embodiment, the protein/protein hydrolysate component is selected from the group consisting of zein, gelatin, hydrolyzed gelatin, collagen, hydrolyzed collagen, casein, caseinate, gliadin, wheat gluten, glutenin and hordein and combinations thereof. [0026] In an embodiment, the polysaccharide is selected from the group consisting of starch, modified starch, dextrin, maltodextrin, hydroxypropylmethylcellulose, dietary fiber, pectin, alginate, natural gum and combinations thereof. [0027] In another embodiment, the present invention provides for a method of manufacturing a chewing gum comprising the step of combining corn protein, a flavoring, and a plasticizer. The plasticizer is selected by calculating the EA/C of the plasticizer, calculating the ED/C of the plasticizer, and selecting the plasticizer whose EA/C is in the range of approximately 0.05 to about 1.5, and whose ED/C is in the range of approximately 0.05 to about 2.0. [0028] In an embodiment, the temperature during the chewing gum-making process is in the range of approximately 25 to about 60° C. [0029] In a further embodiment, the present invention provides for a chewing gum comprising corn protein, a flavoring, and a plasticizer. The plasticizer is selected by calculating the EA/C of the plasticizer, calculating the ED/C of the plasticizer, and selecting the plasticizer whose EA/C is in the range of approximately 0.05 to about 1.5, and whose ED/C is in the range of approximately 0.05 to about 2.0. [0030] In an embodiment, the present invention provides for a chewing gum that is sugar free. [0031] In an embodiment, the present invention provides for a chewing gum that is environmentally friendly. [0032] In an embodiment, the present invention provide for a chewing gum that displays reduced adhesion to environmental surfaces after being chewed. [0033] It is an advantage of the present invention to provide an improved method for selecting plasticizers for chewing gum. [0034] It is an advantage of the present invention to provide a method for predicting effective plasticizers for corn protein by computationally analyzing the chemical structure of a candidate plasticizer, thus reducing trial and error mixing in the laboratory of candidate plasticizers with corn protein. [0035] Still a further advantage of the present invention is to provide an improved chewing gum base. [0036] Another advantage of the present invention is to provide an improved method for making gum base. [0037] Still further an advantage of the present invention is to provide an improved chewing gum. [0038] Another advantage of the present invention is to provide an improved method for making chewing gum. [0039] Moreover, an advantage of the present invention is that the gum base is biodegradable. [0040] Furthermore, an advantage of the present invention is to provide an environmentally-friendly chewing gum. [0041] Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures. DETAILED DESCRIPTION OF THE INVENTION [0042] The present invention provides improved plasticizing agents that can be used in producing gum bases and chewing gum compositions. The present invention additionally provides gum bases and chewing gum compositions, including the plasticizers. By using the plasticizer selection method of the present invention, chewing gum cuds can be ingestible and more environmentally friendly than conventional chewing gum cuds. In this regard, the gum cuds resulting from the present invention have less adhesive characteristics, resulting in reduced adhesion of improperly discarded gum cuds to environmental surfaces such as wood, concrete, fabric, carpet, metal, and other sources. [0043] Zein is a protein of the prolamine class present in maize. While zein has polar amino acid groups in its main chain, its side chains are composed of more than 50% nonpolar amino acid residues such as leucine, isoleucine, valine, alanine, phenylalanine and glycine. This kind of structure makes zein insoluble in water at neutral pH but highly swellable. Its amphiphilic nature makes zein incompatible with most common plasticizers. Currently, few effective plasticizers of zein are known. Such plasticizers include propylene glycol, ethylene glycol, acetic acid, lactic acid, poly(propylene glycol), poly(ethylene glycol), glycerol, ethanol and fatty acids. [0044] A plasticizer varies the firmness of gum base by interposing itself between the macromolecular chains of a target compound. This is best accomplished when the attractive forces between the molecules of both components are similar. If the attractive forces are sufficiently dissimilar, immiscibility will result. Attraction forces between molecules typically include dispersion force, polar forces, hydrogen bonding forces and ionic forces. It is well known that ionic forces and hydrogen-bonding typically play important roles in protein dissolution in aqueous solution. In non-aqueous media, the hydrogen-bonding tends to become the major driving force to form miscible blends between zein and plasticizers. Plasticizers are required to possess sufficient electron donors and electron acceptors in their molecular structures in order to form effective hydrogen bonding with zein macromolecules. In this regard, due to the amphiphilic nature of zein, the most effective plasticizers for zein are those that possess a balance of hydrophobic and hydrophilic portions in their molecular structures similar to zein. [0045] It has been surprisingly found that effective plasticizers of zein can be predicted by assessing the composition of electron acceptors and electron donors within a given candidate plasticizer. One must first calculate the ratio of electron acceptors to the total number of carbon atoms (EA/C) of the candidate plasticizer. The next step is to calculate the ratio of electron donors to the total number of carbon atoms (ED/C) of the candidate plasticizer. The most effective plasticizers of zein appear to be those whose EA/C is in the range of approximately 0.05 to about 1.5, preferably approximately 0.08 to about 1.0, most preferably approximately 0.15 to about 0.67; and whose ED/C is in the range of approximately 0.05 to about 2.0, preferably approximately 0.1 to about 1.1, and most preferably approximately 0.3 to about 0.9. [0046] The most preferential ranges stated above are those that most closely encompass the EA/C and ED/C values (using the same ratio calculation process) of zein, which are approximately 0.30 to about 0.37 and approximately 0.57 to about 0.59, respectively. It is well known in chemical parlance that “like dissolves like,” which is why the most effective plasticizers for zein are those compounds that possess amphiphilic properties similar to zein. [0047] With regard to selecting candidate plasticizers, electron acceptors can include hydrogen in hydroxyl (—OH), carboxylic (—COOH), amino (—NH—), imine (═NH), and sulfhydryl (—SH) groups. The electron donors can include oxygen, sulfur, nitrogen in hydroxyl, carboxylic, ester, ketone, ether, amino, imine, sulfhydryl functional groups and non-conjugated carbon-carbon double bonds. [0048] Compounds suitable as candidate plasticizers may include hydroxyl acid/hydroxyl acid ester/polyhydroxy acid groups consisting of dibutyl tartrate, dipropyl tartrate, diethyl tartrate, ethyl lactate, propyl lactate, butyl lactate, hydroxybutyric acid, glycolic acid, malic acid dibutylester, malic acid dipropylester, malic acid diethylester, hydroxybutyric acid butylester, hydroxybutyric acid propylester, hydroxybutyric acid ethylester, glycolic acid butylester, glycolic acid propylester, glycolic acid ethylester, polylactic acids, polyhydroxybutyric acid, polyglycolic acid or hydroxyl acid copolymers, mono-/di-glycerides organic acid consisting of propanoic acid, oleic acid, linoleic acid, linolenic acid, abietic acid, dihydroabietic acid, dehydroabietic acid, rosin and the mixtures. [0049] Chewing gum generally consists of a water soluble gum base, a water soluble sweetener, and flavors. The insoluble gum base generally comprises elastomers, resins, fats and oils, softeners, and inorganic fillers. The elastomers of the present invention can include ingestible polymers such as various forms of zein, including α-zein, β-zein, γ-zein, δ-zein, as well as other corn proteins. [0050] Selected plasticizers can be blended with zein or other corn proteins to form ingestible elastomer substances. This can be done at approximately 20 to about 65° C., preferably at approximately 35 to about 55° C. In order to produce an environmentally-friendly gum base, the plasticized zein elastomer can be further combined with other ingestible ingredients that may include polysaccharides, proteins or their hydrolysates, ingestible acids emulsifiers, and lipids. Polysaccharides may include native starches, modified starches, dextrins, maltodextrin, hydroxypropylmethylcellulose, dietary fibers, pectins, alginates, carrageenan, gellan gum, xanthan gum, gum arabic, guar gum or other natural gums. The preferred polysaccharides are maltodextrin and high-conversion dextrins. Preferably, the chewing gum bases comprise about approximately 5 to about 10% by weight polysaccharides. Among digestible proteins, hydrolyzed collagens or gelatins are preferred; the preferred content is approximately 10 to about 20% by weight in the base. [0051] The chewing gum bases of the present invention can have a corn protein content of approximately 10 to about 90%, preferably approximately 20 to about 70%, and most preferably approximately 30 to about 60% by weight based on the total weight of the base. Furthermore, the gum base can have a plasticizer content of approximately 5 to about 50%, preferably approximately 10 to about 40%, and most preferably approximately 20 to about 30% by weight based on the total weight of the base. [0052] The gum base can also include fillers and optional minor amounts of ingredients such as colorants, antioxidants, etc. [0053] Fillers/texturizers may include magnesium and calcium carbonate, ground limestone, silicate types such as magnesium and aluminum silicate, clay, alumina, talc, titanium oxide, mono-, di- and tri-calcium phosphate, cellulose polymers, such as wood, and combinations thereof. [0054] Colorants and whiteners may include FD&C-type dyes and lakes, fruit and vegetable extracts, titanium dioxide, and combinations thereof. [0055] The base may or may not include wax. An example of a wax-free gum base is disclosed in U.S. Pat. No. 5,286,500, the disclosure of which is incorporated herein by reference. [0056] In addition to a water insoluble gum base portion, a typical chewing gum composition includes a water soluble bulk portion and one or more flavoring agents. The water soluble portion can include bulk sweeteners, high intensity sweeteners, flavoring agents, emulsifiers, colors acidulants, fillers, antioxidants, and other components that provide desired attributes. [0057] Bulk sweeteners include both sugar and sugarless components. Bulk sweeteners typically constitute 5 to about 95% by weight of the chewing gum, more typically, 20 to 80% by weight, and more commonly, 30 to 60% by weight of the gum. [0058] Sugar sweeteners generally include saccharide-containing components commonly known in the chewing gum art, including, but not limited to, sucrose, dextrose, maltose, dextrin, dried invert sugar, fructose, levulose, galactose, corn syrup solids, and the like, alone or in combination. [0059] Sorbitol can be used as a sugarless sweetener. Additionally, sugarless sweeteners can include, but are not limited to, other sugar alcohols such as mannitol, xylitol, hydrogenated starch hydrolysates, maltitol, lactitol, and the like, alone or in combination. [0060] High intensity artificial sweeteners can also be used in combination with the above. Preferred sweeteners include, but are not limited to sucralose, aspartame, salts of acesulfame, alitame, saccharin and its salts, cyclamic acid and its salts, glycyrrhizin, dihydrochalcones, thaumatin, monellin, and the like, alone or in combination. In order to provide longer lasting sweetness and flavor perception, it may be desirable to encapsulate or otherwise control the release of at least a portion of the artificial sweetener. Such techniques as wet granulation, wax granulation, spray drying, spray chilling, fluid bed coating, coacervation, and fiber extension may be used to achieve the desired release characteristics. [0061] Usage level of the artificial sweeteners will vary greatly and will depend on such factors as potency of the sweetener, rate of release, desired sweetness of the product, level and type of flavor used and cost considerations. Thus, the active level of artificial sweetener may vary from 0.02 to about 8%. When carriers used for encapsulation are included, the usage level of the encapsulated sweetener will be proportionately higher. [0062] Combinations of sugar and/or sugarless sweeteners may be used in chewing gum. Additionally, the softener may also provide additional sweetness such as with aqueous sugar or alditol solutions. [0063] If a low calorie gum is desired, a low caloric bulking agent can be used. Example of low caloric bulking agents include: polydextrose; Raftilose, Raftilin; Fructooligosaccarides (NutraFlora); Palatinose oligosaccharide; Guar Gum Hydrolysate (Sun Fiber); or indegestible dextrin (Fibersol). However, other low calorie bulking agents can be used. [0064] A variety of flavoring agents can be used. The flavor can be used in amounts of approximately 0.1 to about 15 weight percent of the gum and, preferably, about 0.2 to about 5%. Flavoring agents may include essential oils, synthetic flavors or mixtures thereof including, but not limited to, oils derived from plants and fruits such as citrus oils, fruit essences, peppermint oil, spearmint oil, other mint oils, clove oil, oil of wintergreen, anise and the like. Artificial flavoring agents and components may also be used. Natural and artificial flavoring agents may be combined in any sensorially acceptable fashion. [0065] By way of example and not limitation, examples of the present invention will now be given. EXAMPLE 1 [0066] The ratios of electron acceptors to carbon number (EA/C) and electron donors to carbon number (ED/C) values of various materials have been calculated and are shown in Table 1. In order to determine the calculations the following materials were used. Propanoic acid, ethyl propionate and propylene glycol were obtained from Spectrum Chemical Mfg. Corp. (New Brunswick, N.J.). Ethyl lactate, n-propyl lactate, isopropyl lactate, butyl lactate, ethylhexylester of lactic acid were obtained from PURAC America Inc. (Lincolnshire, Ill.). Lactic acid was obtained from Archer Daniels Midland Co. Polylactic acid oligomers were synthesized by L. A. Dreyfus Co. (Edison, N.J.). Dibutyl tartrate was obtained from Aldrich Chemical Co. (Milwaukee, Wis.). All other samples were obtained from Mallinckrodt Baker, Inc. (Phillipsburg, N.J.). [0067] The following procedure was followed: 10 g of liquid samples were added to individual vials containing Ig zein powder (Freeman Industries, L.L.C., Tuckahoe, N.Y.). The vials were vigorously shaken on a Wrist Action Shaker for 30 minutes and set aside for 24 hours at room temperature. The contents of the vials were then examined to determine their miscibility. [0068] It was found that when the EA/C value of a given plasticizer was within approximately 0.10 to about 0.67, and the ED/C value of that plasticizer was in the range of approximately 0.3 to about 1.0, the zein/plasticizer mixture displayed complete miscibility. If either the ED/C or the EA/C of a given plasticizer was out of these ranges, no true solution was observed. TABLE 1 zein/plasticizer EA/C ED/C mixture (1:10) zein 0.30-0.37 0.57-0.59 Propanoic acid 0.33 0.67 Clear, one phase Diethyl tartrate 0.25 0.75 Clear, one phase Dibutyl tartrate 0.17 0.5 Clear, one phase Propylene glycol 0.67 0.67 Clear, one phase Ethyl lactate 0.20 0.6 Clear, one phase n-Propyl lactate 0.17 0.5 Clear, one phase Isopropyl lactate 0.17 0.5 Clear, one phase Butyl lactate 0.14 0.4 Clear, one phase Butandiol 0.5 0.5 Clear, one phase Lactic acid 0.67 1 Clear, one phase Acetic acid 0.5 1 Clear, one phase Ethylene glycol 0.33 0.67 Clear, one phase monomethyl ether PLA dimer 0.33 0.83 PLA trimer 0.22 0.78 PLA tetramer 0.17 0.67 PLA oligomer Mixture of di- tri-, tetra- mers Clear, one phase ethyl propionate 0 0.4 insoluble ethylhexylester of 0 0.27 insoluble lactic acid methanol 1 1 Cloudy, two phase butanol 0.25 0.25 Cloudy, two phase Good miscibility 0.10-0.67 0.3-1.0 range EXAMPLE 2 [0069] As seen above in Example 1, the best plasticizers of zein are those compounds whose EA/C is from approximately 0.10 to about 0.67 and whose ED/C is from approximately 0.3 to about 1.0. Nevertheless, compounds whose EA/C and ED/C ratios fall within the broader ranges of approximately 0.05 to about 1.5 and approximately 0.1 to about 2.0, respectively (but outside the ideal ranges shown in Example 1), can still be effective plasticizers of zein in the presence of an additional plasticizing component (See Table 2). [0070] For example, as shown below, oleic acid and linoleic acid cannot individually dissolve zein directly as the method shown in Example 1. However, miscibility did occur when 10 g of 10% zein/aqueous isopropanol solution were mixed with 0.3 g oleic acid (Spectrum Chemical Mfg. Corp., New Brunswick, N.J.). After the solvent evaporated at ambient temperature overnight, a clear and soft film was formed. This method can also be used for the test of solid plasticizers such as rosin (a mixture of the isomers of abietic acid, dehydroabietic acid, dihydroabietic acid), malic acid and tartaric acid. TABLE 2 zein /plasticizer EA/C ED/C mixture (10:3) rosin 0.05 0.20 Clear, brittle film Oleic acid 0.06 0.17 Clear, soft film Conjugated 0.06 0.22 Clear, soft film Linoleic acid Linolenic acid 0.06 0.28 Polypolyene glycol 0.02 0.66 Cloudy, oily (2 phase) (PPG2000) PPG1200 0.04 0.65 Cloudy, oily (2 phase) Malic acid 0.75 1.25 Slight cloudy film, no macro phase separation Tartaric acid 1 1.5 Opaque film, no macro phase separation Miscible Range 0.05-1.5 0.1-2 EXAMPLE 3 [0071] In this example, a gum base containing zein and dibutyl tartrate was prepared. Thirty-six grams of zein were added to a C. W. Brabender mixer (Model DDRV501, Brabender Corp., South Hackensack, N.J.), followed by the addition of 15 g dibutyl tartrate and 21 g distilled water during agitation. The mixture became pasty and translucent after 30 minute at 50° C./32 rpm. The mixture was then discharged. The base was soft and elastic. EXAMPLE 4 [0072] In this example, a gum base containing zein and butyl lactate was prepared. Thirty-six grams of zein were added to a Brabender mixer followed by 20 g butyl lactate and 10 g distilled water during agitation. The mixture became pasty and translucent after 30 minute at 50° C./32 rpm. Subsequently, 6 g gelatin (Leiner Davis Gelatin) and 6 g maltodextrin (Grain Processing Corp., Muscatine, Iowa) were added into the mixer. After 30 minutes of further mixing, the mixture was discharged. The base was soft and elastic at room temperature. EXAMPLE 5 [0073] In this example, a gum base containing zein and propyl lactate was prepared. Thirty-six grams of zein were added to a Brabender mixer followed by 20 g propyl lactate and 10 g distilled water during agitation. The mixture became pasty and translucent after 30 minute at 50° C./32 rpm. Subsequently, 6 g gelatin and 6 g maltodextrin was added into the mixer. After 30 minutes of further mixing, the mixture was discharged. The base was soft and elastic at room temperature. EXAMPLE 6 [0074] In this example, a gum base containing zein and ethyl lactate was prepared. Thirty-six grams of zein were added to a Brabender mixer, followed by 20 g ethyl lactate and 10 g distilled water during agitation. The mixture became pasty and translucent after 30 minute at 50° C./32 rpm. Subsequently, 6 g gelatin and 6 g maltodextrin were added into the mixer. After 30 minutes of further mixing, the mixture was discharged. The base was soft and elastic at room temperature. EXAMPLE 7 [0075] In this example, a gum base containing zein and propanoic acid was prepared. Thirty-six grams of zein were added to a Brabender mixer followed by 20 g propanoic acid and 10 g distilled water during agitation. The mixture became pasty and translucent after 30 minute at 50° C./32 rpm. Subsequently, 6 g gelatin and 6 g maltodextrin were added into the mixer. After 30 minutes of further mixing, the mixture was discharged. The base was soft and elastic at room temperature. EXAMPLE 8 [0076] In this example, a gum base containing zein and malic acid was prepared. Fifteen grams of malic acid were added to a beaker with 15 ml water and stirred until a clear solution was obtained. Thirty-six grams of zein were added to a Brabender mixer along with the malic acid/water solution described above. The mixture became homogenous and paste-like after 30 minute at 50° C./32 rpm. Subsequently, 6 g gelatin and 6 g maltodextrin were added into the mixer. After 30 minutes of further mixing, the mixture was discharged. EXAMPLE 9 [0077] In this example, a gum base containing zein and polylactic acid oligomers was prepared. Thirty-six grams of zein were added to a Brabender mixer and 20 g polylactic acid oligomers (L. A. Dreyfus Co., Edison, N.J.) was added during agitation. The mixture became pasty and translucent after 60 minute at 80° C./32 rpm. The mixture was then discharged. The base was soft and elastic. EXAMPLE 10 [0078] In this example, a gum base containing zein, lactic acid, and oleic acid was prepared. Thirty-six grams of zein were added to a Brabender mixer followed by 20 g 88% food grade lactic acid (Archer Daniels Midland Co., Decatur, Ill.) and 10 g oleic acid during agitation. The mixture became pasty and translucent after 60 minute at 80° C./32 rpm. The mixture was then discharged. The base was soft and elastic. EXAMPLE 11 [0079] In this example, a gum base containing zein, propanoic acid, and conjugated linoleic acid was prepared. Thirty grams of zein were added to a Brabender mixer and then 20 g food grade propanoic acid and 10 g conjugated linoleic acid (Stepan Co., Maywood, N.J.) were added during agitation. The mixture became pasty and translucent after 60 minute at 80° C./32 rpm. Subsequently, 6 g gelatin and 6 g maltodextrin were added into the mixer. After 30 minutes of further mixing, the mixture was discharged. The base was soft and elastic. EXAMPLE 12 [0080] In this example, a sugarless gum containing zein and polylactic acid oligomers was prepared. To a Brabender mixer (setting at 60° C. and 30 rpm), 50 g of the gum base prepared in Example 9 was added and agitated for 10 minutes. 6 g mannitol and 0.5 g acesulfame K were then added. After 10 minutes of further mixing, 0.5 ml fruit flavor was added and mixed for another 10 minutes. After discharge, the gum dough was rolled and pressed into a thin sheet and cut into gum cubes. EXAMPLE 13 [0081] In this example, a sugarless gum containing zein and dibutyl tartrate was prepared. To a Brabender mixer (setting at 60° C. and 30 rpm), 50 g of the gum base prepared in Example 3 was added and agitated for 10 minutes. 6 g gelatin and 6 g maltodextrin were then added into the mixer. After 30 minutes of further mixing, 6 g mannitol and 0.5 g acesulfame K were added. After 10 minutes of further mixing, 0.5 ml fruit flavor was added and mixed for an additional 10 minutes. After discharge, the gum dough was rolled and pressed into a thin sheet and cut into gum cubes. EXAMPLE 14 [0082] In this example, a sugarless gum containing zein, lactic acid, and oleic acid was prepared. To a Brabender mixer (setting at 60° C. and 60 rpm), 50 g of the gum base prepared in Example 10 along with 25 g sugar and 0.5 g acesulfame K were added and mixed for 10 minutes. 0.5 ml fruit flavor was added and mixed for an additional 10 minutes. After discharge, the gum dough was rolled and pressed into a thin sheet and cut into gum cubes. EXAMPLE 15 [0083] In this example the removeabililty of gum prepared pursuant to the present invention was examined. Three pieces of gum made in Examples 12 and 13, respectively, were washed in a water bath overnight and finger-kneaded in lukewarm water for 2 minutes. The gum cuds were then pressed onto a concrete block and heated in an oven at 40° C. for 3 days. The gum cuds were then aged at room temperature for 1 week. The gum cuds were found cracked and easily removable by a common broom. [0084] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.	Methods of making gum base and chewing gums and products so produced are provided. To this end, methods for selecting effective plasticizers for corn protein are provided. The plasticizer selection methods are based on a calculation of the ratio of electron acceptors to the total number of carbon atoms of the plasticizer, and a calculation of the ratio of electron donors to the total number of carbon atoms of the plasticizer.	0
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to magnetic tape recording apparatus and more particularly to storage bins for storing an endless loop of magnetic recording tape which is folded back and forth in serpentine configuration. 2. Description of the Prior Art In high speed magnetic tape duplicating and recording systems as well as in data processing equipment utilizing magnetic tape, it is now common practice to utilize loop storage bins in which a long length of tape is folded back and forth in serpentine fashion in a generally rectangular shaped storage bin having front and back walls which are separated only slightly more than the width of the tape to be stored. In such apparatus, the tape is normally loaded from the top and caused to loop back and forth upon itself as the other end is withdrawn from the bottom of the loop pile. The tape's own weight is used to compact the serpentine loops within the bin. Prior art U.S. Pat. Nos., which may be of interest by way of general background, are Gibson 2,542,506, MacDonald 2,889,491, Fritzinger 2,908,767 and Boyden 3,201,525. One of the problems associated with prior art loop bin constructions has been overcoming the friction between the bottom surface of the bin and the portions of the tape being withdrawn from the bottom of the loop pack. One prior art attempt to overcome this problem has been to use a plurality of closely spaced rollers to form the bottom and partial side portions of the bin. Another solution has been to utilize a plurality of short, belt conveyers such as is shown in the U.S. Pat. No. 4,000,516 of Kazuo Watanabe et al. However, such solutions are mechanically complex and quite expensive in that the rollers are conveyers must be provided with expensive low friction bearings and smoothly polished surfaces. Another prior art problem is associated with the perturbations in speed of the portion of the tape being withdrawn from the bottom of the stack due to differing frictional forces on various portions of the folded loops at the bottom of the bin. The primary prior art solution to the problem has been to utilize a heavy flywheel controlled damping roller in the tape transport mechanism. Although such means are successful in reducing tape speed fluctuations at the recording or playback head with a measure of success, there is definitely room for improvement. Still another problem with prior art storage bin designs relates to the ability of the device to store a large quantity of folded tape within a particular bin volume. It has been found that the amount of tape which can be stored in a particular bin volume is directly related to the manner in which the tape is folded within the bin, i.e., it appears that the more folds there are, the larger the quantity of tape that can be stored within a given volume and the more mobile the tape is at the bottom of the stack. SUMMARY OF THE PRESENT INVENTION A primary objective of the present invention is to provide a tape storage bin for tape transport apparatus and the like which is simple in construction and inexpensive to manufacture. Another objective of the present invention is to provide a loop bin for tape transports and the like which enables a large quantity of tape to be stored within a particular bin volume. Another objective of the present invention is to provide a loop bin for tape transport apparatus and the like having means for aiding the removal of the tape from the bin bottom and for assisting in the damping of perturbations in the tension of the tape portion being withdrawn from the bin. Still another objective of the present invention is to provide a loop bin for tape transport apparatus and the like having means for improving the distribution and compaction of tape within the bin. In accordance with a presently preferred embodiment of the present invention, a loop bin is provided which includes a front and rear wall separated slightly more than the width of the tape to be stored, entry and exit openings at the top, a resilient distributing arm located proximate the entry opening, a compliant length of flexible material suspended from each side of the bin and forming a cantenary configured bin bottom, and a compliant damper loop disposed midway down the bin and adjacent the exit side thereof for damping exiting tape tension fluctuations and assisting in the stacking of tape within the bin. An important advantage of the present invention is that it utilizes inexpensive materials, is simple is construction and is highly effective in operation. Another advantage of the present invention is that it enables tape to be packed more densely into the same bin volume as compared to prior art devices. These and other objects and advantages of the present invention will no doubt become apparent to those of ordinary skill in the art after having read the following detailed disclosure of a preferred embodiment. IN THE DRAWING FIG. 1 is a partially broken perspective view schematically illustrating a tape transport and loop bin in accordance with the present invention; and FIG. 2 is a cross-sectional view of the bin taken along the line 2--2 of FIG. 1 to more clearly illustrate the various components thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 of the drawing, there is shown at 10 a representation of a tape transport apparatus including a guide roller 12, a flywheel damping roller 14, a pair of drive capstans 16 and 18, a pair of pinch rollers 20 and 22, a record/playback head 24 and a pair of exit guide rollers 26 and 28. Also carried by the transport housing are a pair of guide straps 27 and 29. Disposed in front of and beneath the transport 10 is a loop storage bin 30 in accordance with the present invention and including a rectangular body 32 forming an internal chamber for receiving a loop of tape 33, a distributor arm 34, a compliant bottom strap 36 and a damper mechanism 38. The entry aperture for the bin is defined by the guide strips 27 and 29 and the exit aperture is defined by a partition 40 which extends from the top of the bin downwardly for about one third the vertical length thereof. Body 32 is comprised of a pair of planar sheets of smooth surfaced material such as metal, glass or plastic and which form the front and rear walls 50 and 52 respectively of the bin. In the preferred embodiment, the rear wall 52 is made of an aluminum sheet and the front wall 50 is made of a transparent glass sheet which permits observation of the loop stack during operation. In order to discharge the static electric charge which accumulates on the tape, strips of conductive ribbon 53 are adhesively affixed to the inside surface of wall 50 and grounded to the unit chassis at top and bottom. The front and rear walls are separated by a distance slightly wider than the width of the tape to be stored and are affixed together by means of side walls 54 and 56, bottom wall 58 and the partition 40. Referring now additionally to FIG. 2, the distributor arm 34 is comprised of a bowed length of flexible metal or plastic which is affixed at one end to the guide member 27 by means of suitable fastening means and has its distal end rolled back upon itself as illustrated at 60. In addition, an adjustable weight 62 is affixed to a portion of the distal end of the distributor arm. In the preferred embodiment, the arm 34 is comppised of a 10 inch length of 0.005 inch thick SST shim stock and has a width of 1/2 inch. Arm 34 is designed so as to resiliently engage the tape in oscillatory fashion at a frequency determined by its own resonance characteristics. It is free to fall to a tape engaging position shown by the dashed lines 34', bounce therefrom into an upper position shown by the dashed lines 34", and then return to the tape engaging position. Each time the arm strikes the tape 33 which is being fed into the bin at high speed, typically 240 inches per sec., it causes a wave action to be set up therein as illustrated at 35 which causes the moving tape to distribute itself rather short folds as it falls into the bin. The bottom strap 36 in the preferred embodiment is comprised of a length of 0.005 thick shim stock, one end 70 of which is affixed to wall 56, and then other end 72 of which is affixed to wall 54. The strap is freely hung within the bin chamber and is allowed to assume a cantenary configuration. Because it is a compliant length of material which is free swinging, it will move and deform slightly as the tape 33 is drawn from the bottom of the stack, and the motion and deformations thereof will aid both the packing of the loop and the removal of the tape from the bottom of the stack. Damper member 38 is also comprised of a length of 0.005 thick shim stock having both ends affixed to the lower end of the partition 40 and serves to provide a means for drawing lateral motion of tape 33 as its tension increases and decreases during its withdrawal from the bottom of the bin. In addition, since the tape stack extends above its lower extremity, the movement of damper member 38 also tends to aid in compacting the tape within the bin. In operation, the loop is initially deposited within the bin and is threaded through the various guide rollers and capstans of the transport 10. Arm 34 is then lifted and the transport is energized to begin motion of the tape. As the tape accelerates into the bin, it will follow the upper surface of guide 28 and enter bin 30 in a straight line and form rather large loops as it folds into the bin. Arm 34 is then released and allowed to strike the incoming tape as illustrated. Upon striking the tape, arm 34 will be driven upwardly and as a result of the strike, a wave action will be induced in the tape as depicted. The net result of the wave action is that it causes the tape to fold back upon itself in short loops instead of the longer loops which would otherwise occur. Arm 34 then returns and strikes the tape again and again at a rate determined by its stiffness and the mass of the weight 62 affixed to its distal end. It has been found that a weight of approximately 2.5 grams causes an arm of the type described to oscillate at about 180 swings per minute and to create tape loops of approximately four inches between folds. By operating the device with arm 34 held out of engagement with the tape and allowing the bin to be fully filled with free formed loops, the stack will assume a particular stack heighth within the bin. However, by releasing the arm 34 and allowing it to perform its function, the stack heighth will be reduced by approximately 25% indicating a substantial compaction of the stack as a result of the action of arm 34. The vibratory distortion and motion of strap 36 and member 38 can also be readily observed during operation of the device and a substantial improvement in damping of tape speed perturbations at the output of the damping roller 14 can be observed. Although a single preferred embodiment of the present invention has been disclosed herein, it will be appreciated that various alterations and modifications of the various components will become apparent to those skilled in the art after having read this disclosure. For example, the configuration of arm 34 and damper member 34 might be modified somewhat for ease of manufacture or other reasons while still performing the same function. Moreover, the length of strap 36 may be increased or decreased to achieve optimum operation for a particular weight of tape. It is therefore intended that the appended claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.	A loop bin for use with tape transport apparatus including a front wall 50 and rear wall 52 separated by slightly more than the width of the tape to be stored, a pair of entry and exit openings at the top, a resilient distributing arm 34 located proximate the entry opening a compliant length of flexible material 36 suspended from each side of the bin and forming a catenary configured bin bottom, and a compliant damper loop 38 disposed midway down the bin and adjacent the exit side thereof for damping exiting tape tension fluctuations and assisting in the stacking of tape within the bin.	1
BACKGROUND OF THE INVENTION The present invention is directed toward a movable roof structure and more particularly toward a telescoping movable roof structure for a patio, swimming pool, building or the like. Numerous types of facilities such as swimming pools, tennis courts and patios are frequently used in the open air during fair weather. During inclement weather, however, it would be desirable to provide such facilities with a cover or roof. In order to fulfill both desires, roofs have been proposed in the past which are collapsible or movable so that a closed top can be provided if desired or the same can be opened. Such movable roofs are also sometimes desirable with various other types of buildings. The proposed prior art movable roof structures known to Applicant are not believed to have been satisfactory. They have either been too complex and, therefore, too difficult and expensive to construct or have been capable of opening only a small portion of the roof. For example, while the structures shown in U.S. Pat. Nos. 3,566,555; 3,589,084 and 4,073,098 are not very complex, they provide for the movement of only a single panel member or section and accordingly only a portion of the roof can be opened. The structure shown in U.S. Pat. No. 4,283,889 is capable of opening the entire roof but only because the roof is relatively small as only one roof panel is also moved in this structure. U.S. Pat. Nos. 1,006,374 and 2,094,801 show movable roof structures comprised of a plurality of panels which are adapted to telescope with respect to each other so that a larger portion of the roof can be opened. This is a similar concept to Applicant's invention. However, the structure shown in these two latter patents can be used only on a particular predetermined structure. They can be adapted to other structures only by making changes to the roof system itself or the supporting structure or both. This, of course, increases the cost of the roofing system since each must be specially designed. SUMMARY OF THE INVENTION The present invention is capable of substantially opening the entire roof and also reduces the cost of movable roofs since the operative components of the invention can be prefabricated in standard sizes and are easily adaptable to substantially any support structure. The telescoping movable roof structure of the present invention is comprised of a plurality of roofing units which are in an overlapping shinglelike arrangement. The roofing units are telescopically movable with respect to each other between a closed position where they partially overlap each other and an open position where they are substantially stacked one on top of the other. Each roofing unit includes a pair of end extrusions and an elongated intermediate extrusion. Each extrusion carries roof panels on the side edges thereof so that said panels are joined end to end in the direction of the width of the roof. The extrusions also carry wheel and track members which cooperate with the extrusion immediately above and below so that the roofing units are movable. A power driven chain or the like moves the roofing units between their closed and open positions. BRIEF DESCRIPTION OF THE DRAWINGS For the purpose of illustrating the invention, there is shown in the accompanying drawings one form which is presently preferred; it being understood that the invention is not intended to be limited to the precise arrangements and instrumentalities shown. FIG. 1 is a perspective view of a telescoping roof structure constructed in accordance with the principles of the present invention and showing the roof in its closed position; FIG. 2 is a cross-sectional view taken through the line 2--2 of FIG. 1; FIG. 3 is a view similar to FIG. 2 but showing the roof structure in its open position; FIG. 4 is a cross-sectional view taken through the line 4--4 of FIG. 3; FIG. 5 is a perspective view of a plurality of extrusion members which carry the roof panels and which allow for movement thereof with respect to each other; FIG. 6 is a perspective view of the uppermost extrusion member shown in FIG. 5; FIG. 7 is a cross-sectional view taken through the line 7--7 of FIG. 6; FIG. 8 is a perspective view of one of the intermediate extrusion members shown in FIG. 5; FIG. 9 is a perspective view of the lowermost extrusion member shown in FIG. 5, and FIG. 10 is a perspective view of a part of a pair of cooperating extrusion members showing a locking detent feature thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail wherein like reference numerals have been used throughout the various figures to designate like elements, there is shown in FIG. 1 a perspective view of a telescoping roof structure constructed in accordance with the principles of the present invention and designated generally as 10. Roof 10 is comprised of a plurality of roofing units 12, 14, 16, 18 and 20. While five such roofing units are shown in the application, it should be noted that this is by way of example only, any number of units could be used depending on the dimensions of the roof or area being covered. The roofing units are movable between a closed position as shown in FIG. 2 wherein the lower edge of each roofing unit overlies the upper edge of the roofing unit immediately below it on the incline and an open position as shown in FIG. 3 wherein the roofing units are stacked substantially one on top of the other. Movement is provided by a driven chain 22 which extends through the height of the roof and passes around sprockets or pulleys 24 and 26. The driving means is substantially identical to a standard electric garage door opener. Each of the roofing units is comprised essentially of two major components: a plurality of roofing panels and a plurality of extrusion members which not only support and carry the roofing panels but also provide a means for allowing the roofing units to be telescopically movable. In the embodiment of the invention shown in FIG. 1, each of the roofing units includes three roofing panels, a pair of intermediate extrusion members and an end extrusion member at each remote side edge of the unit. For illustration purposes, the roofing panels of unit 18 have been identified as 28, 30 and 32; the intermediate extrusion members as elements 34 and 36 and the end extrusion members as elements 38 and 40. Similarly, the roofing panels of the lowermost roofing unit 20 have been identified as elements 42, 44 and 46 and the intermediate extrusion members of roofing unit 20 are identified as elements 48 and 50. The foregoing is, of course, by way of example only as a system could be built having a greater number or a smaller number of roofing units and a greater number or smaller number of roofing panels within each unit. Each of the intermediate extrusion members has an upper portion and a lower portion. The upper portions of all of the intermediate extrusion members are substantially identical to each other. It should be understood, therefore, that the following description of one of the intermediate extrusion members applies equally to all of the other members. While not specifically described, any elements identified by prime reference numerals will be understood to be substantially identical to the element being described. As shown most clearly in FIGS. 5-9, each of the upper portions of the intermediate extrusion members is elongated in shape and is substantially box-shaped in cross section. It includes a lower wall 52, side walls 54 and 56 and partial top walls 58 and 60. An elongated opening 62 remains between the ends of the partial top walls 58 and 60. The side walls 54 and 56 include flanges 64 and 66 at the top and bottom thereof. As shown in FIG. 4, the purpose of these flanges is to allow for attachment of the roofing panels thereto. A pair of roofing panels are secured to each of the intermediate extrusion members so that the panels are in a substantially end to end relationship. Each panel may be comprised of wood, composite board, plastic or any other suitable material such as shown at 68 and is preferably covered by a thin sheet metal or plastic skin 70 or the like. The skin 70 is used to secure the panels to the flanges 64 and 66 of the side walls 54 and 56 through the use of a plurality of rivets or screws or the like 72. Carried on the bottom wall 52 of the extrusion member and running the length thereof is a bottom track 74. Bottom track 74 faces upwardly and lies directly under the opening 62. Each of the partial upper walls 58 and 60 also carry a track 76 and 78, respectively. Top tracks 76 and 78 also run substantially the length of the extrusion and face downwardly. The side wall 56 carries an inwardly extending tab 80 which functions as a stop member. As shown most clearly in FIGS. 8 and 9, a portion of the partial upper wall 58 is cut out as shown at 82 to function as part of a detent member which will be described more fully hereinafter. The lower portion of each extrusion member includes a pair of downwardly extending and spaced apart walls 84 and 86. A pair of wheels 88 and 90 are carried by and between the walls 84 and 86 through axles 92 and 94, respectively, passing through apertures in the walls. Mounted on the outside of walls 84 and 86 are pairs of wheels 94 and 96. There may be two or more pairs of such wheels. Wheels 94 and 96 are mounted to the walls 84 and 86 through the use of leaf springs such as shown at 98 in FIG. 10. The wheels 94 and 96 are normally located in a position above the wheels 88 and 90 and are also spring biased upwardly by the leaf spring 98. The extrusion member 102 shown in FIG. 6 represents the intermediate extrusion member of the uppermost roofing unit 12 and is constructed substantially as described above. As can be seen from FIG. 5, however, the remaining extrusion members include a forward extension of the walls 84 and 86. FIG. 9 represents the lowermost intermediate extrusion member 48 and includes the forward extensions 84' and 84'. A rail or track 174 is located on top of the extensions 84' and 86' and is substantially identical to and a continuation of the bottom track of the extrusion member 48. The extensions 84' and 86' also carry a wheel 188 and a wheel 196 which are mounted in substantially the same manner as the wheels 88 and 96 described above. A second side wheel similar to wheel 94 is also located on the wall of the extension 84' although the same cannot be seen in FIG. 9. FIG. 8 illustrates an intermediate extrusion member 34 from the roofing unit 18. This extrusion member 34 is substantially identical to the extrusion member 48 except that it includes a downwardly extending leg 100 at the forward end of the extensions 84" and 86". This leg 100 carries wheels 288, 294 and 296 adjacent the lower end thereof which are again substantially identical to wheels 88, 94 and 96 and are mounted in substantially the same manner. Extending outwardly from the side wall of the extension 86" is a tab 102 which will cooperate with the tabs similar to tab 80 located within the inner wall of the extrusion members to act as a stop means. As can be seen from FIGS. 2, 3 and 5, there are essentially three types of intermediate extrusion members. Extrusion member 102 shown in FIG. 6 is used in the top roofing unit 12; extrusion member 48 shown in FIG. 9 is used in the bottom roofing unit 20 and the extrusion members utilized in the other roofing units 14, 16 and 18 are similar to the extrusion member 34 shown in FIG. 8. The only difference between these extrusion members is the length of the leg 100. The length of the leg increases going upwardly toward the top of the roof. Thus, it can be seen that leg 104 is longer than leg 102 which is longer than leg 100. Although the end extrusion members such as 38 and 40 have not been specifically described, these members can be constructed to be substantially identical to the intermediate extrusion members which have been described. Alternately, these end extrusion members can be modified somewhat since only one side edge is being used to support a panel. For example, the flanges 64 and 66 can be removed from one side edge to leave a flat outer wall and to thereby give a neater appearance. In addition, various types of trim or finishing material can be utilized with the end extrusions or the intermediate extrusions for appearance purposes. The telescoping roof structure of the invention cooperates with the building or other substructure to which it is applied through a track member 106 shown most clearly in FIGS. 4 and 5. A plurality of track members 106 will be employed, one underlying each of the line of extrusion members. The track member 106 may be mounted on a beam or rafter of the building or, if constructed of heavy enough material, may itself function as a beam or rafter. Track member 106 includes a centrally located upwardly facing track 108 and two downwardly facing tracks 110 and 112. The cooperation between the various extrusion members and the track 106 can best be seen from FIGS. 2-5. From FIG. 4, it can be seen that the lowermost part of extrusion 48 extends downwardly into the track member 106 so that the wheel 88' rides on the track 108. At the same time, wheels 94' and 96' are biased upwardly and ride on tracks 110 and 112. The spring biased mounting of these wheels keeps the various interconnecting members under some tension to prevent unwanted shaking and movement. In a like manner, wheel 88" from the lower portion of extrusion member 34 rides on the track 74' located within the extrusion member 48. Likewise, wheels 94" and 96" ride on the downwardly facing tracks 76' and 76". It should be readily apparent to those skilled in the art that the same cooperation and interconnection between the track and wheel means of the various extrusions are substantially identical throughout. As stated above, the roofing units are moved by way of the driven chain 22. A rigid bar 114 or the like extends upwardly from the chain 22 to one of the panels of the uppermost roofing unit 12. When the roof is in its closed position as shown in FIG. 2, the roofing units are interlocked with each other by the detent means shown in FIG. 10. The detent means is comprised of at least one of the wheels 94 or 96 from each of the extrusion members entering the opening or cut out portion 82 from the extrusion member below. The wheel 94 is moved upwardly into the opening by the force of the leaf spring 98. The wheels 94 and openings 82 are arranged on each of the extrusion members so that each locks into the member above and below it when the roof is in its totally closed position as shown in FIG. 2. When it is desired to open the roof, the chain 22 is moved so that rod 114 begins to move downwardly. The downward force will eventually overcome the force of the leaf spring so that the wheel 94 will roll out of the opening 82 and resume its proper position on the track 78. As the uppermost roofing unit 12 moves downwardly and overlies the roofing unit 14, eventually one of the stop members 102 will engage the stop member 80 so that both roofing units 12 and 14 will then be moved in unison. In a like manner, the force of the spring loaded detent means of the extrusion members of roofing unit 14 will eventually be overcome and roofing units 12, 14 and 16 will be moved in unison. This will continue until all of the roofing units are stacked in the position shown in FIG. 3. To close the roof, the opposite procedure is followed. The chain is moved upwardly and the bar 114 begins to pull the roofing unit 12 upwardly. Eventually the detent means will engage and a second set of stop members 80 and 102 will engage. At this point, the roofing unit 12 will then carry the roofing unit 14 along with it and this procedure will repeat itself until the roof is closed. It should be readily apparent to those skilled in the art that the various extrusion members function not only to carry the roofing panels but also serve as the wheel and track means allowing for movement. The extrusion members can be prefabricated in standard sizes to cover substantially any size roof. For wider roofs, one merely needs to use wider roof panels or add further extrusion members in each roofing unit. For higher roofs, one need merely add an additional roofing unit. If needed, the stop members 80 and 102 and the openings 82 forming the detent means can be relocated so that the roofing units will be evenly spaced when in the closed position. The term "extrusion" has been used to refer to the various extrusion members since it is intended that these elements be made by an extrusion process. The extrusion members can be made of aluminum or other light metal or substantially any other suitable material. It is not absolutely necessary that these elements be made by an extrusion process. It is possible within the scope of the present invention that they be made by any process and the term "extrusion member" will apply equally thereto. The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and accordingly reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.	A movable roof structure for a patio, building, swimming pool or the like is comprised of a plurality of roofing units which are in an overlapping shingle-like arrangement. The roofing units are telescopically movable with respect to each other between a closed position where they partially overlap each other and an open position where they are substantially stacked one on top of the other. Each roofing unit includes a pair of end extrusions and an elongated intermediate extrusion. Each extrusion carries roof panels on the side edges thereof so that said panels are joined end to end in the direction of the width of the roof. The extrusions also carry wheel and track members which cooperate with the extrusion immediately above and below so that the roofing units are movable. A power driven chain or the like moves the roofing units between their closed and open positions.	4
BACKGROUND [0001] This disclosure relates to suspended ceiling systems and more particularly to a novel and improved system using perforated metal ceiling panels that include a non-woven fibrous facing material on the lower exposed surface of the panel creating an aesthetically pleasing and durable with fire safety qualities in a sound absorbing paneled ceiling system. [0002] By way of background but not limitation, suspended-ceiling systems typically include grid members that provide for oppositely extending ceiling panel support flanges. In these systems, the edges of the ceiling panels are installed by laying them in the panel opening created by the grid members. There are also suspended-ceiling systems that have grid members, which include channels designed to grip the vertically extending edges of metal ceiling panels. These ceiling panels are typically installed by snapping the flanges up into the grid member channel, and are generally referred to as “snap-up ceiling panels.” Typical lay-in grid panels are manufactured from slag wool fiber and/or recycled paper and expanded perlite or fiberglass to create light weight aesthetic ceiling panels. Some of these grid panels do not provide durability or sound absorption qualities that are desired for use in commercial, residential and industrial space. [0003] In view of the above, it should be appreciated that there is a need for a ceiling panel that provides for increased durabilty and sound absorption. The present disclosure satisfies these and other needs and provides further related advantages. SUMMARY [0004] The disclosure may be described as a novel and improved suspension ceiling panel that includes enhanced sound deadening qualities and increased durability. In the preferred embodiment the panel comprises a metallic panel substrate including a plurality of apertures of varying sizes. The body is further adapted to be connected to the ceiling grid members. The outer exposed surface of the metallic panel substrate is covered by a non-woven fibrous material that is adhered thereto. The multi-dimensioned apertures formed in the panel substrate in combination with the non-woven fibrous fabric on the lower exposed surface of the panel not only provides the appearance of a traditional acoustical panel but provides desirable sound absorption and resistance to flame spread and smoke generation. [0005] Other features and advantages of the disclosure will be set forth in part in the description which follows and the accompanying drawings, wherein the embodiments of the disclosure are described and shown, and in part will become apparent upon examination of the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0006] The above mentioned and other features of this disclosure and the manner of obtaining them will become more apparent and the disclosure will be best understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings in which: [0007] FIG. 1 is a perspective view of one type of ceiling system illustrating fibrous faced ceiling panels; [0008] FIG. 2 is a sectional view of the ceiling system, taken along lines 2 - 2 , illustrating the fibrous faced ceiling panels connected to a grid system; [0009] FIG. 3 is a top view of the ceiling panel illustrating the spacing and sizes of the perforations; [0010] FIG. 4 is a top view of the ceiling panel illustrating an alternate perforation pattern; [0011] FIG. 5 is a perspective view of a ceiling system illustrating the fibrous faced ceiling panels transitioning from a first elevation to a second elevation; [0012] FIG. 6 is another perspective view of a ceiling system illustrating the fibrous faced ceiling panels transitioning from a first elevation to a second elevation; [0013] FIG. 7 is a perspective view of a ceiling system illustrating the transition from the fibrous faced ceiling panels to other types of ceiling panels; and [0014] FIG. 8 is a perspective view of a ceiling system illustrating curved fibrous faced ceiling panels. DETAILED DESCRIPTION [0015] While the present disclosure will be described fully hereinafter with reference to the accompanying drawings, in which a particular embodiment is shown, it is to be understood at the outset that persons skilled in the art may modify the disclosure herein described while still achieving the desired result. Accordingly, the description that follows is to be understood as a broad informative disclosure directed to persons skilled in the appropriate art and not as limitations on the present disclosure. [0016] As illustrated in the drawings, FIG. 1 illustrates a portion of an assembled suspension ceiling incorporating snap-up fibrous faced ceiling panels 10 in accordance with the present disclosure. In such a ceiling panel system, grid members 12 are interconnected to form a grid structure 13 . The grid members 12 are arranged to form openings 14 sized to receive the ceiling panels 10 . The grid members 12 are suspended from the building structure by wire hangers 16 or other supporting structures. [0017] To create the grid structure 13 , a row of parallel evenly spaced grid members 12 are suspended by wire hangers 16 . Each row of the grid members 12 are spaced apart to accommodate the size of the fibrous faced ceiling panels 10 . To accommodate a 2 foot by 2 foot ceiling panel, the grid members 12 would be spaced apart 2 feet on-center. The grid structure 13 also includes a second set of grid members 18 that are perpendicularly oriented in relation to the first set of grid members 12 to create the opening required for hanging the panels 10 . [0018] The fibrous faced ceiling panels 10 are normally rectangular, usually square in shape, and are preferably made out of metal. The panels 10 are durable in that they are impact resistant, self-supporting do not sag or fracture when perforated. Depending upon the ceiling design used, it may be desirable to shape the panels 10 into a square or curved shape, as shown in FIG. 8 , but other shapes may be utilized. Other shapes would include transition panels, as shown in FIGS. 5 and 6 , which allow the transition from a first elevation to a second elevation. FIG. 7 illustrates a decorative transition panel 55 without the facer material, which can be a low gloss or high gloss, reflective panel. While the preferred material used in fabricating the fibrous faced ceiling panels 10 is metal, other materials may be used including gypsum, wood, wood fiber, plastic and other substrate materials that allows perforation while retaining the basic shape and stiffness of the fibrous faced ceiling panels 10 . Metal and plastic material, such as polycarbonate, are preferred since panels can be molded or stamped to include a desired shape or to form various edge configurations for connection to the grid structure 13 . The fibrous faced ceiling panels 10 include an interior face 20 and an exterior face 22 . The panels 10 may also include a hinge 24 along a first corner 25 of the panel 10 to permit the panel to be pivoted to an open position with respect to the grid system 13 . The panel 10 preferably includes flanges 26 along the edges 58 of the panel 10 . While a flanged edge and a hinged edge are disclosed, other edge configurations may be used to secure the panels 10 to the grid system. [0019] The fibrous faced ceiling panels 10 , as shown in FIG. 1 , illustrates the panels 10 connected to the grid structure 13 by use of flanges 26 . It is beneficial to use the hinge 24 to support the ceiling panel 10 when all metal ceiling panels become as large as 4 feet by 4 feet, because the panels become awkward to install and remove due to their relatively large size and weight. Further illustrations of the use of a hinge can be found in U.S. Pat. No. 6,467,228, incorporated herein by reference. When working with a piece of sheet metal with such a large surface, any improper handling may result in damage to the overall finish of the ceiling panel 10 . Also, by using the hinge 24 that spans the length of the ceiling panel 10 , the weight of the panel is evenly distributed across the entire corner 25 of the panel 10 , preventing rippling that would be apparent in the bottom surface 20 of the panel 10 . Furthermore, once the ceiling panel 10 is connected to the grid members 12 , the ceiling panel 10 will automatically be in alignment to allow for easy closure by pivoting the ceiling panel 10 upward and snapping in the flanges 26 into the grid. [0020] FIG. 2 is a cross section of FIG. 1 taken along line 2 - 2 looking in the direction of the arrows and shows the grid member 12 and the hinge 24 along an corner 25 of a first ceiling panel 10 and the flanged edge 26 of a second ceiling panel 10 . The grid member in this example 12 is fabricated out of a single piece of die-formed sheet metal. The grid member 12 after fabrication includes a bulb portion 34 , a channel 36 and a double layer bridge portion 38 that connects the bulb portion 34 and the channel 36 . The overall shape of the grid member 12 is to give the member 12 strength to prevent flexing. Typically, apertures (not shown) are placed along the length of the bridge portion 38 so that wire hangers 16 can be threaded through and wrapped around the bulb portion 34 . Once the wire hanger 16 , as shown in FIG. 1 , which can be in the form of a wire, is threaded through an aperture (not shown) and around the bulb portion 34 , the wire hanger 16 is wrapped around itself several times to prevent it from unraveling. [0021] The bridge portion 38 typically includes slots (not shown) that allow one grid member 12 to be connected to the second grid member 18 to form the grid structure 13 . The channel 36 , as shown in FIG. 2 is formed by bending the double layers of the bridge portion 38 , 90 degrees outward, 90 degrees downward and 90 degrees inward to form a boxed channel 36 . Bottom edges 42 are folded over to act as an engagement edge for the flange 26 and a retaining surface for the hinge 24 . The hinge 24 is formed in the ceiling panel 10 by die-forming the hinge 24 90 degrees upward to create an upwardly extending leg 43 and then die-forming the edge 90 degrees inward to create an inward lip 44 . The inward lip 44 of the hinge 24 rests upon the bottom edge 42 in the channel 36 of the grid member 12 . The flange 26 , shown in FIG. 2 , is formed by die-forming or molding the edge 26 of the ceiling panel 10 upward 90 degrees to form a vertical member 45 and by forming a rib 48 . The ceiling panel 10 is retained to the grid structure 13 by forcing rib 48 past the bottom edge 42 . The rib 48 is properly positioned within the channel 36 when the rib 48 is resting upon the bottom edge 42 . The vertical member 45 biases the rib 48 to prevent the ceiling panel 10 from moving out of position. While use of an edge with a rib 48 is preferred, other grid engagement mechanisms may be used including a lay-in arrangement wherein the edges 26 do not include a flange. [0022] FIG. 2 also illustrates a fibrous facer material 54 adhered to the exterior face 22 of the panel substrate 11 viewable from the environmental area of a building structure. The environmental area of the building structure is defined as the space within a building used by occupants to work or conduct other activities. It is the inhabitable space within a structure. From the environmental area, the fibrous facer material 54 is substantially exposed and viewable by the occupants below. The interior face 20 of the panel 10 is substantially concealed from the environmental area and is not viewable by the occupants below. The fibrous facer material 54 creates an aesthetically pleasing surface that gives the ceiling a soft appearance as opposed to a painted metallic ceiling panel, which has an undesirable shiny appearance. [0023] FIG. 3 is a top view of the fibrous faced ceiling panel 10 that illustrates the positioning of apertures 52 of a first diameter and apertures 53 of a second diameter across the panel 10 . The non-woven fibrous facer material 54 on the exterior face 22 of the panel 10 is adapted to cover the entire face 22 of the panel 10 including the apertures 52 , 53 . When the fibrous facer material 54 is applied to the panel 10 , only the fibrous facer material 54 is visible from below. The panel substrate 11 or the apertures 52 , 53 are not viewable from below. The sound absorption mechanism of the fibrous faced ceiling panels 10 is a combination of resonant absorber sound attenuation due to the resistance in air flow through the pores of the non-woven fibrous facer material 54 and the perforation of the panel 10 . In order to maximize sound absorption at varying frequencies, three main parameters need to be optimized. This includes the extent of perforation of the panel 10 with apertures 52 , the airflow resistance of the fibrous facer material 54 and the plenum height, i.e. the distance between the structure and the ceiling. [0024] FIG. 4 illustrates a top view of an alternate aperture arrangement wherein the panel 10 includes apertures 52 of a first diameter apertures 53 of a second diameter and apertures 55 of a third diameter. The combination of the three aperture sizes enhances the resistance of sound waves of varying frequency. The apertures 52 shown in FIG. 1 are all of a uniform size. [0025] The extent of the perforation of the panel 10 is partially dependent upon the strength of the selected substrate material and its resistance to mechanical impact and to excessive panel flex. Substrates such as metal and plastic can be extensively perforated, while gypsum board is limited to no more than about 20% of its surface area in order to maintain strength. In order to achieve the proper sound deadening qualities, the substrate is perforated from about 10% to about 35% open area. Optimally, the percentage of the open area of the face 50 of the panel 10 should be about 30% to about 33%. [0026] Sound is made up of various frequencies. A cymbal for instance would emit a high frequency whereas a base drum would emit a low frequency. The varying amplitude of the frequencies renders it difficult to provide a medium that is sufficient at deadening sound. A particular media may be efficient at capturing low frequency noise but is incapable of capturing high frequency noise. In order to enhance sound absorption at different frequencies the substrate panel 11 is perforated with apertures of different diameters. More specifically, two or three different aperture sizes are preferred. For the panel 10 to achieve the desired sound deadening qualities, the diameter of the apertures in the panel are from about 0.039 inches to about 0.117 inches to achieve the desired sound deadening qualities. Preferably, the perforated pattern is a combination of 15/128 of an inch apertures and 3/32 of an inch apertures. While circular apertures are preferred, oval triangular, polygonal, square or elliptical shaped apertures can also be used. Apertures with large diameters permit the passage of low frequency sounds with large amplitudes whereas apertures with smaller diameters permit the passage of high frequency sounds with smaller amplitudes. [0027] Spacing between the panels 10 is important in order to gain the maximum benefits from the panels. In order to maximize the sound absorption qualities of the panels, it is sufficient that the gap tolerance between panels is in the range from about zero gap to about ⅜ of an inch and preferably from about a zero gap to a gap of about ¼ of an inch. Spacing between the panels larger than ⅜ of an inch permits excessive sound to be deflected off of the grids 12 and back into the room, reducing the effectiveness of the ceiling system. [0028] In testing of the panel 10 of the present disclosure smoke development and flame spread by the panel resulted in values substantially lower than industry standards. Limiting smoke development in a building fire is essential in order to increase the ability for occupants in the build to escape without being subjected to smoke inhalation. Typically in a fire, smoke inhalation, and not the fire itself cause death to the occupants. [0029] The non-woven fibrous facer material 54 is applied to the panel substrate with use of an adhesive. The adhesive utilized to adhere the non-woven fibrous facer material 54 to the ceiling panel 10 is preferably a hot melt adhesive that is substrate compatible. The adhesive must also be compatible with the type of facer material 54 applied to the panel 10 . While hot melt adhesive is preferred, it is foreseeable that other types of adhesives, such as spray, brush or roll-on adhesives may be used. The sound absorption qualities of the panel are also varied by the type and amount of the glue used on the fibrous facer material 54 . [0030] The panel substrate 11 and fibrous facer material 54 are designed to permit molding or stamping of the panel 10 into desired configurations to create flanges 26 . Transition panels 57 , as shown in FIGS. 5 and 6 or curved ceiling panels, as shown in FIG. 8 may also be created by molding or stamping the panel. Transition panels 57 are used to transition from a first ceiling elevation to a second ceiling elevation and can be formed by bending or curving the panels 10 . In order to permit the panel 10 to be formed into the desired configuration, the panel substrate 11 is preferably made from steel, aluminum or polymer. The fibrous facer material 54 used to cover the exterior face 51 of the panel substrate 11 can be of various materials so long as the material does not rip or tear when formed with the panel. Certain materials when tested such as fiberglass tear or crack when the panel 10 is molded to create flanges 26 or other desired shapes. Preferred materials for use as a fibrous face material 54 include polymer mixtures having polyster fibers. Another such usable material is a combination of NYLON6 and Polyethylene. Polymer mixtures of fibrous materials, permit the passage of airflow through the material 54 and allow the panel 10 to be shaped after the fibrous material 54 has been adhered to the panel 10 without tearing the fibrous face material 54 . [0031] To achieve the desired sound deadening qualities, the panel substrate 11 , in combination with the fibrous facer material 54 should have an airflow resistance from about 900 mks rayls to about 1050 mks rayls. Specific airflow resistance is the product of the airflow resistance of a specimen and its area. This is equivalent to the air pressure difference across the panel 10 divided by the linear velocity of airflow measured outside the panel 10 . The airflow resistance of the fibrous facer material 54 in combination with the perforated panel substrate is critical to the efficiency of the acoustic attenuation process. If the airflow resistance is too high, the material reflects the sound wave as if it were a solid wall. If it is too low, the sound wave freely travels through the material. In either case the sound attenuation is less than optimum. The preferred airflow resistance of the facer material 54 should be about 100 mks rayls to about 600 mks rayls. [0032] Airflow resistance of a panel 10 is defined as the ratio of the pressure drop across the material to the velocity of the gas passing through it and can be expressed in cgs rayls (dyne/cm 2 per cm/sec). Determination of flow resistivity is the main property in describing the acoustical performance of any porous material. Every fibrous material has specific flow resistance characteristics based on its manufacturing process or inherent nature. In the case of composite materials, such as the present panel 10 , which is a combination of the fibrous facer material 54 and the perforated panel 10 , it is important to understand the individual flow resistance of each component. However, for optimum performance of the resultant panel 10 , it is vital to tune the flow resistance of the entire system fibrous facer material 54 and panel substrate 11 to maximize sound absorption. As previously stated, this optimum airflow resistance is about 900 mgs rayls to about 950 mks rayls. [0033] In most cases, plenum height 64 behind the panel 10 is limited and therefore the sound absorption performance of the panel 10 is restricted by the short plenum gap, as shown in FIG. 2 . In order to further enhance the sound absorption of the panel 10 with a short plenum height a second layer of porous insulation material 56 such as glass fiber, mineral fiber, thermoplastic polymeric fiber, thermosetting polymeric fiber, carbonaceous fiber, milkweed fiber, or foam insulation, (with preference to polyolefin microfiber melt blow products) can be applied to the interior face 20 of the panel 10 . [0034] The panels 10 are designed with four edges 58 that are adapted to be connected to the grid structure 13 . The panels 10 can be connected to the grid structure 13 using various edge configurations. The edges 58 of the panel 10 can include the vertical member 45 and a rib member 48 . This allows the panel to be snapped into the bottom edges 42 of the grid members 12 and 18 . In yet another alternative, the panel 10 does not include edges 25 and simply lays into the openings 14 created by the grid structure 13 . [0035] While the concepts of the present disclosure have been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired and protected. [0036] There are a plurality of advantages that may be inferred from the present disclosure arising from the various features of the apparatus, systems and methods described herein. It will be noted that alternative embodiments of each of the apparatus, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the inferred advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of an apparatus, system, and method that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the invention as defined by the appended claims.	A suspension ceiling panel that includes enhanced durability, sound absorption and increased fire safety qualities. The panel comprises a body substrate including a plurality of apertures. The body is further adapted to be connected to the ceiling grid members. The outer exposed surface of the body substrate is covered by a non-woven fibrous material. Apertures in the body substrate in combination with the non-woven fibrous material on the lower exposed surface of the panel provides the appearance of a traditional acoustical panel but provides desirable sound absorption and fire resistive qualities.	4
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of rayon fibres, filaments or films with a viscose process. More particularly, it relates to an improved process for spinning a viscose solution into an acidic spinbath containing no zinc salt. 2. Description of the Related Art The production of regenerated cellulosic products like rayon fibre, films and filaments by viscose process, involves an initial step the conversion of a cellulosic material to alkali cellulose by treatment with caustic soda solution. The alkali cellulose is then shredded, aged and further converted into cellulose xanthate by treatment with carbon disulphide. The xanthated cellulose is then dissolved in dilute sodium hydroxide solution to obtain desired content of cellulose and alkali. The solution so obtained is called viscose which is further filtered, ripened, deaerated and then extruded through a spinnerette into a spin bath mainly comprising of sulphuric acid, zinc sulphate and sodium sulphate. The spinbath of conventional process essentially contains zinc sulphate or some other soluble zinc salts which acts as a regeneration retardant. Zinc salts present in either viscose or in spinbath forms zinc xanthate salts in the filament, which is a more stable compound than sodium cellulose xanthate and thereby allows the stretching phenomenon of filaments. Zinc is known to be highly toxic chemical and the presence of even in ppm range in effluent is objectionable specially for drinking purposes and marine lives. Other than pollution problem, the high use of zinc sulphate in viscose process has certain other notable disadvantages. It is expensive and it has also, to a certain degree, the tendency to form encrusting deposits on spinning equipments. In addition to zinc sulphate in spin bath, the other viscose modifiers are also used like polyethylene glycols, polyethylene oxides, certain amines, formaldehyde, etc. as auxiliary regeneration retardants, specially when high strength fibres are required. All these viscose organic modifiers not only cause processing difficulties but also pose a serious problem of air and stream pollution. They are also associated with adverse physiological effects. It was, therefore, thought desirable at least in certain commercial applications like production of regular rayon to develop a process which is completely zinc free. SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to develop a completely zinc-free viscose process to manufacture regenerated cellulosic fibre. It is therefore, another object of the present invention to provide a process and spinbath system with reduced stream and air pollution. It is a further object of this invention to propose a novel process which eliminate zinc or zinc salts in the viscose solution and the spin bath but still provides satisfactory regeneration retardation such that necessary strength can be imparted to the fiber being extruded through the spin bath. It is yet another object of this invention to propose such a process which will employ readily available chemicals in the spin bath which will be cheap and thereby make the process economical and also reliable. A further object of the invention is to provide a viscose rayon manufacturing process and a spin bath solution in a said process which promotes the filament hydration and xanthate stability in a manner similar to that of zinc but without the disadvantages associated with zinc namely generation of pollutant stream and encrustation format on spinnerettes or spin bath pipings. Yet another object of this invention is to provide a process to produce fibres of improved characteristics with respect to lustre, softness and handle. It is also an object of this invention to eliminate zinc salt in existing viscose industries without adversely affecting the production. Yet another object of the present invention is to provide a zinc free viscose process to produce normal rayon of variety of quality like fibres of different deniers, length, dope dyed (pigmented) and other ranges of regular rayon. Yet another important object of this invention is to provide a process to produce fibres with improved dye absorption characteristics. A still further object of the invention is to propose such an improved process in which there is no additive used in the preparation of the viscose solution. Thus, it is yet another object of this invention to propose an improved process for the production of viscose rayon in which no additive is used in the preparation of the viscose solution and use of zinc or zinc salts is totally eliminated in the spin bath as regeneration retardants. Other objects and advantages of the present invention will be apparent from the following description. In achieving our goal, we have tried many bivalent and trivalent metal ions such as magnesium sulphate, ferrous sulphate, aluminium sulphate (alum), etc. and also some organic compound such as urea and the decomposition rate constant of cellulose xanthate was studied. As a result of extensive experiments carried out to replace a toxic zinc compound from the spin bath with a non-toxic compound, we found that aluminium sulphate (alum) as the best suited chemical which is also found economical and environmentally compatible over zinc sulphate. Effluent pollution is also appreciably reduced. The regular rayon fibre cross section is serrated and non-uniform. The geometry of the cross section of the filament has a great influence on quite a few important characteristics e.g. lustre, cover, handle and feel. It is known that uniform and non-serrated cross section with `C` shaped or flat produces fibres of high lustrous appearance. It has been observed that the process developed by us has enabled us to achieve one goal and convinced us that zinc sulphate can easily be replaced by alum in the spin bath solution without facing any problem in the running plant by stopping the make up addition of zinc salt and gradual addition of aluminium sulphate in the spin bath. We have further observed that we are able to produce fibres with uniform `C` shaped cross-section thus ensuring improved optical properties. We have still further observed that the dye affinity of the fibres of present invention is greater than fibres of zinc process and requires less amount of dye to get similar dyeing effect as regular rayon of zinc process. In conventional process of producing viscose rayon fibre, the presence of zinc salts in viscose or spin bath is essential, as the formation of the skin structure of the filament depends upon the formation of zinc cellulose xanthate. It is also claimed that the zinc compound causes substantial increase in the plasticity of zinc cellulose xanthate gel so it can be stretched much more rapidly than sodium-cellulose-xanthate. Although many theories have been proposed to explain the importance of zinc and zinc-cellulose-xanthate in the structural formation of filaments in viscose process, but however, it is still an open question whet her or not zinc-cellulose-xanthate plays any vital role in subsequent structure formation. There are mentions that in some cases the acidic spin bath does not contain zinc salt, but to compensate the effect of zinc, many tertiary mono-amine such as methylol, dimethylamine, methylol metha methyl amine, methylol diethylamine or other amines like dimethylamines, aldehydes like formaldehyde are used either in viscose or in spin bath as a regeneration retardant or additives in spin bath. All these modifiers are associates either in one way or other with high cost or air or stream pollution. No practical method has been devised for the recovery of these additives from the spin bath and accordingly, there is a gradual build up of the additives or their reaction products in the spin bath and thereby these are present in effluent wash water routed to the waste treatment. This is highly undesirable because they add appreciably to the biological oxygen demand (B.O.D.) which must be lowered to a level to meet standards established by Central and State agencies. There are also some mentions where aluminium compounds are suggested for use in the spin bath with or without zinc sulphate, but none of these approaches have reached upto commercialization stage. Briefly stated our invention provides a process for the production of regenerated cellulose fibre having increased lustre and softness and having substantially `C` cross section with well developed skin which comprises soaking a rayon grade pulp in caustic soda solution of 17.5 to 18.5% to produce alkali cellulose having 33-34% cellulose and 15.55 to 16.00% sodium hydroxide, shredding the alkali cellulose, ageing same to get a viscous solution having viscosity of 35-75 ball fall seconds, converting the alkali cellulose into cellulose xanthate by reaction with 28 to 33% carbon di-sulphide, preparing a viscose solution from the xanthate by dissolving same in dilute caustic soda solution, said viscose solution having 6-11% cellulose and 52-60% caustic soda/cellulose ratio, allowing the viscose solution to ripen and thereafter subjecting the ripened solution to spinning in a spin bath characterized in that the spin bath is zinc free spin bath containing 6.5-12% sulphuric acid, 0.3-2.0% aluminium sulphate [Al 2 (SO 4 ) 3 ] and 16-26% sodium sulphate followed by stretching the spun filament and thereafter, regenerating, desulphurizing, bleaching, finishing and drying the filament. Still more particularly the following steps are followed in our process. A rayon grade pulp is steeped in 17.5-18.5% caustic soda solution. Excess alkali is removed by pressing to a suitable extent to get alkali cellulose having 33-34% cellulose and 15.5-16% sodium hydroxide. Alkali cellulose is shredded and aged to get desired viscosity of 35-75 ball fall sec. Alkali cellulose is then treated with 28-33% carbon disulphide. The cellulose xanthate so formed is dissolved in dilute caustic soda solution to prepare a viscose containing 6-11% cellulose and 52-60% caustic soda/cellulose ratio. The viscose prepared is filtered, deaerated, and ripened to get 7-12 Hottonroth number. It is spun in a spin bath containing 6.5-12% sulphuric acid, 0.3-2.0% aluminium sulphate (Al 2 (SO 4 ) 3 ) and 18-26% sodium sulphate. Other metal salts such as magnesium sulphate, ferrous sulphate may also be used. In the spinning process zinc salt is totally eliminated. Spin bath temperature from 35°-60° C. and spinning speed of 30 to 75 m/min can be kept. Filaments so formed can be stretched to 35-70% in air. Fibre/filaments are then completely regenerated desulphurised, bleached, finished and dried in a usual manner. The cross section of the fibres prepared by the process of present invention (i.e. alum process) is shown in FIG. 1 of the accompanying drawings compared with regular rayon of zinc process and HWM zinc process fibre. From the figures, it is clear evidence that the fibres of present process have uniform `C` shaped cross section with well developed skin and some folded section in between. Such cross section also showed increased lustre and soft feel. There are a few paper suggestions in the prior art where the use of zinc or zinc salts has sought to be replaced by aluminium salts. One such prior art suggests the use of high concentrations of aluminium sulphate which can be about half of or equal to the amount of sulphuric acid present in the spin bath. This prior art further suggests the use of additives like aluminium hydroxide in the viscose solution. This combination of aluminium salts has not enabled a commercially viable process. Moreover, the properties of the rayon fibre are not as enhanced as those of the invented process. Another prior art suggests use of a specially prepared viscose base alkali solution which involves special neutralization techniques using sodium carbonate and sodium hydroxide. The spin bath suggested aluminium sulphate. The viscose base solution is thus to be specially prepared as otherwise the precipitation of the fibres in the spin bath can not be achieved. This process is also not commercially viable and renders the process very costly because of the requirement of special equipments centrifuge and chemicals in the preparation of the viscose base solution. A third prior art process suggests the use of an aqueous precipitating bath which employs equal amounts of sulphuric acid and aluminium sulphate. There is a possibility of using aluminium sulphate in amounts upto double that of sulphuric acid. In addition to the above the process proposes to use organic compounds like naphthalene sulfonic acid in substantial amounts. This makes the process very complicated and expensive. In a fourth prior art (C.A.-99-1983-5 4949d) the effect of ions of polyvalent metals on the decomposition rate of cellulose xanthate in a coagulating bath has been studied. It suggests the replacement of zinc salts in the spin bath with equal amounts of aluminium sulphate. Thus, the amounts of aluminium sulphate is about 20% of the amount of sulphuric acid which is very high percentage. The study shown reduction in hydrolysis of the xanthate. Obviously, there is nothing on fibre properties and obtaining C-cross section fibre. A fifth prior art process recommends the use of a spinning bath having usual sulphuric acid, sodium sulphate and zinc sulphate and in addition substantial amounts of aluminium sulphate which is triple the amount of zinc sulphate. Such a process does not avoid zinc salts and hence the fibre properties are influenced by the presence of zinc salts. A sixth prior art however recommends use of zinc free coagulation bath containing polyvalent metal ions. The bath composition has very high concentrations of polyvalent metal ions like Aluminium. However because of the use of such high concentrations of polyvalent metal ions, the ultimate properties of the spun fiber obtained are far from satisfactory and the prior art fibers do not combine all the properties of the fiber obtained by the process of the present invention. Yet another seventh prior art is again a paper work which suggests the replacement of zinc sulphate in the spinning bath by aluminium sulphate. No details are available. However if aluminium sulphate is used to replace zinc sulphate, the amount ought to be substantial. We have, by conducting experiments have found that high lustrous fiber "C" character cannot be obtained by any of the prior art suggestions. It is also not possible to combine other beneficial properties like high strength, crimp and slowing of retardation of regeneration and high stretchability and dye affinity. Quite unexpectedly and surprisingly it has been discovered by us by extensive research that a unique process can be achieved producing a fiber having all the beneficial properties and particularly "C" character in addition to reducing environmental pollution if the spinning bath composition is correlated to its components and the aluminium sulphate amount kept as low as possible. We have further discovered that the mere optimisation of amount of aluminium sulphate will not work and that its amount should be co-related to the amounts of the other ingredients so as to give a balanced spinning bath capable of ensuring quick precipitation of the fiber, retarded regeneration of viscose, easy and efficient solidification of precipitated viscose, high spinnability and stretchability high lustour, smooth fiber surface characteristics, soft feel of fiber on handling, less use of chemicals and repeatability. There is no process to our knowledge anywhere practiced or anywhere published or even suggestive which will combine all the above properties and on top of its produce "C" character fiber. This is borne out by the Examples given herein. Use of aluminium sulphate in amounts less than 0.3% will not ensure sat is factory regeneration retardation. Use of aluminium Sulphate in amount more than 2.0% will hamper with the production of "C" cross section fiber thereby affecting the lustrous character. Further the amount of aluminium sulphate should be as low as 1/10th to 1/90th of Sodium Sulphate and 1/5th to 1/50th of Sulphuric acid. Such low amounts of aluminium Sulphate only help in obtaining a commercially viable, highly dependable and repeatable process. In searching leas expensive and non toxic chemicals, we found aluminium sulphate (alum) as the best suited compound to replace zinc totally from the spin bath. The alkali soluble aluminium compounds like aluminium sulphate, aluminium hydroxide or sodium aluminate in small quantities can further be added in the viscose to serve as a dispersing agent and act as an auxiliary supporter to slow down the decomposition rate constant of xanthate in spinning process. In course of our experimental investigations, we have discovered a method for commercial production of regular rayon where zinc compound is eliminated completely from the process with the use of aluminium sulphate in the spin bath. Viscose may or may not contain any additives. The invention is carried out by the spinning of viscose in zinc free spin bath containing alum under conditions which result in filament having appreciable amount of skin equivalent to or even more than that of produced by the presence of zinc sulphate. The stretchability of the newly formed tow does not suppress when alum is present in the spinbath. The viscose filaments are spun into an acidic spinbath containing sulphuric acid, sodium sulphate and aluminium sulphate and subjected to air stretching to an extent of 35 to 70%. The filaments or staples are then completely regenerated in dilute acidic aqueous bath at 80°-100° C. The further refining stages like desulphurization, bleaching, finishing are done in a conventional manner. In carrying out the viscose spinning of present invention, we may use any suitable viscose composition of the well known procedure for forming rayon filaments. It is preferred in preparing the viscose to use cellulose having uniform D.P. distribution of from 300 to 1000 DP made by kraft, sulphite, cotton linter or cold caustic refined pulps. The process may be carried out with conventional or modified viscose composition comprising about 6-11% cellulose and 52-60% caustic soda/cellulose ratio. The viscose solution may be prepared according to the usual practice to have a ripening index 7°-12° H. by xanthating the alkali cellulose with desired amount of Carbon disulphide, say 28 to 33%. It is also preferred to spin the viscose into a zinc free spinbath containing 6.5 to 12% sulphuric acid, 18 to 28% sodium sulphate and 0.3-2.0% aluminium sulphate at temperature 35° to 60° C. The filaments so formed are stretched in air to a desirable extent, say 35 to 70%. The presence of aluminium sulphate in spinbath of alum process does not exhibit any problem in CS 2 or salt recovery system, on the contrary it increases the release of CS 2 and H 2 S gases compared with the spinbath containing zinc sulphate. Al 2 (SO 4 ) 3 in spinbath is also found to be economic and environmentally beneficial over zinc sulphate. The effluent pollution is appreciably reduced. The invention will be further described by means of following specific examples which are given for illustration only and are not to be taken as, in any way, limiting to the invention. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying photomicrograph FIG. 1 is enlarged (about 1000×) cross sectional view of the fibres of present invention (alum process). FIG. 2 is an enlarged (about 1000×) cross sectional view of the regular rayon fibres prepared by zinc process (i.e. ZnSO 4 in spinbath. FIG. 3 is an enlarged (about 1000×) cross sectional photomicrograph of commercial HWM fibres. DESCRIPTION OF THE PREFERRED EMBODIMENT EXAMPLE 1 Normal rayon grade pulp was steeped in 17.5% sodium hydroxide solution, the excess alkali was removed by pressing. The alkali cellulose so obtained was shredded and aged. The aged alkali cellulose was treated with 30% Carbon disulphide on the basis of alpha cellulose present in the alkali cellulose. The sodium cellulose xanthate so formed was then dissolved in dilute caustic soda solution to form viscose. The viscose contained 10% cellulose and 5.8% sodium hydroxide having ball fall 55 sec. It was then filtered, deaerated and ripened to 10° H. Ripened viscose was extruded into a spinbath containing 8% sulphuric acid, 23% sodium sulphate and 0.46% aluminium sulphate at temperature 50° C. The spinbath was free from zinc salt. The filaments were stretched 40-60% in air and cut into staples. The fibres were then completely regenerated in acidic aqueous bath 95° C., desulphurized, bleached and finished and dried in a conventional way. The fibre so obtained has following properties in addition to having C-crossed section ______________________________________Denier 1.51Cond. tenacity gpd 2.63Wet tenacity gpd 1.35Wet/Cond. ratio % 51.4Cond. elongation % 20.8Wet elongation % 23.6______________________________________ EXAMPLE 2 Viscose was prepared in the same manner as described in Example 1 excepting that NaOH was % and CS 2 was %. The cellulose content in the viscose was 9.5% and alkali 5.4%. Viscose viscosity at the time of spinning was 48 ball fall sec. at 20° C. Viscose was extruded into a spinbath containing 95 gpl sulphuric acid, 6 gpl aluminium sulphate and 290 gpl sodium sulphate at 48° C. The newly formed filaments of 1.2 denier were stretched to 48% in air and given usual refining and finishing treatments. The fibres have good lustre, soft hand and feel with `C` shaped cross section. The fibres have following physical properties: ______________________________________Denier 1.17Cond. tenacity gpd 2.50Wet tenacity gpd 1.24Wet/Cond. ratio % 49.7Cond. elongation % 17.5Wet elongation % 22.0______________________________________ EXAMPLE 3 A viscose solution as described in Example 1 using indigenous pulp having ripening index 9.6° H. was spun for 3 denier fibre by extrusion into a spinbath containing 8.5% sulphuric acid, 0.46% Al 2 (SO 4 ) 3 and 23% sodium sulphate. Spinbath was maintained at 50° C. and spinning machine speed was 45 m/min. Filaments were stretched to abut 47% in air, cut into staples and usual fibre refinings were carried out. The fibres have smooth almost non-serrated surface with `C` shaped cross section. Other physical characteristics are given below: ______________________________________Denier 3.30Cond. tenacity gpd 2.35Wet tenacity gpd 1.22Wet/Cond. ratio % 51.9Cond. elongation % 20.0Wet elongation % 23.3______________________________________ EXAMPLE 4 viscose solution with 10.3% cellulose and 5.7% alkali was prepared with 30% Carbon disulphide having viscosity of 57 ball fall sec. It was filtered, deaerated and ripened to 10.3° H. This viscose was extruded into a spinbath containing 7.7% sulphuric acid, 1.1% aluminium sulphate and 22.5% sodium sulphate at temperature 47° C. Filaments were stretched to 52% in air. Normal refining treatment as described in Example 1, was given to fibres. The fibres have following properties in addition to having C-shaped cross section. ______________________________________Denier 1.53Cond. Tenacity gpd 2.60Wet Tenacity gpd 1.31Wet/cond. ratio % 50.5Cond. elongation % 20.0Wet elongation % 23.5______________________________________ EXAMPLE 5 Viscose A and B were prepared as in Example 1 and 2 and spun in a spinbath containing 95-100 gpl sulphuric acid, 6 gpl aluminium sulphate and 290 gpl sodium sulphate through a spinnerette having 19000 holes 70 micron orifice dia. Spinning conditions were set for 1.15 D and 1.5 Denier fibre, stretched 50% in air and cut into staples A and B of 44 mm length. The cut fibres A and B were separately regenerated completely, desulphurized, bleached, finished and dried in usual manner. The fibres were tested for dye affinity and yarn strength. ______________________________________ FIBER A FIBER B______________________________________Fiber quality 1.15 D × 44 mm 1.5 D × 44 mmDenier 1.13 1.41Cond. tenacity gpd 2.67 2.38Wet tenacity gpd 1.32 1.18Wet/Cond. ratio % 49.3 49.4Cond. elongation % 19.0 18.8Wet elongation % 23.8 22.0Yarn Strength:Spinning count 40 40Lea test (lbs) 57.6 53.4C.S.P. 2304 2136Dye affinity Greater than Greater than regular rayon regular rayon of Zinc process of Zinc process Good fastness Good fastness bright shade bright shadeHandle/feel pleasant hand/ pleasant hand/ soft feel soft feel.______________________________________ The action of acid salts is to reduce the speed of regeneration. The most important, however, is the dehydrating and salting out action, which is common to all melts. The ammonium salts have greater coagulating power than sodium salts, whereas the coagulating power of Mg ++ is of the same order as Na + . The heavy metals like Zn ++ , Fe ++ are more effective than Na + or Mg ++ . The regeneration retardation of these cations is about the same order as their coagulating power. Further a very significant effect along these lines is obtained with aluminium salts especially aluminium sulphate. Invented processes have been successfully tried for commercial production of various quality of fibres with denier ranging from 0.8 to 12. EXAMPLE 6 Viscose prepared as described in Example 1, having salt index 10° H. was spun in two different spinbaths. Sample A was spun in a bath containing 8.5% sulphuric acid 0.5% Magnesium sulphate and 23% sodium sulphate at 49° C. The filaments were stretched to 42%. Sample B was spun in a spinbath containing 8.5% sulphuric acid 0.5% ferrous sulphate and 22.5% sodium sulphate at 49° C. Filaments stretched to 45%. The tow stretchability in case of MgSO 4 has been reduced to some extent whereas the reduction in fibre brightness was observed, in case of FeSO 4 in spinbath. Fibre cross-section in both cases were irregular with some folds in one or two sides. Fibre properties are mentioned below: ______________________________________ Sample A Sample B______________________________________Denier 1.57 1.45Tenacity gpd conditioned 2.54 2.52wet 1.22 1.24W/C Ratio % 48.0 49.2Elongation %Conditioned 19.5 18.7Wet 22.6 23.8______________________________________ EXAMPLE 7 Successful commercial trial has been taken with a viscose prepared as described in Example 1, and spun in a spinbath containing 7.8-10% sulphuric acid, 0.4-0.6% aluminium sulphate and 22-24% sodium sulphate at 46°-49° C. Fibres have been given normal desulphurization, bleaching and finish treatments. Remarkable improvement in brightness, lustre and soft feel was observed over normal fibre of zinc-process. Fibre properties are given below: ______________________________________ A B C D 1.5 D × 57 1.2 D × 51 0.8 D × 51 12 D × 51Fiber quality mm BB mm mm mm______________________________________Denier 1.51 1.16 0.9 11.7Tenacity gpdConditioned 2.54 2.57 2.59 1.75Wet 1.31 1.37 1.32 0.71W/C ratio % 51.7 53.0 51.0 40.6Elongation %Conditioned 19.1 18.1 18.4 28.5Wet 23.2 19.3 18.9 34.6Crimp % 12 12 16 12Yarn strength 1836 2076 2100 --(of 40's) CSP______________________________________ All fibers had C-shaped cross section. Though we have discussed the details of use of aluminium sulphate to replace the zinc salt, it is possible to use other bivalent and trivalent metal ions, such as magnesium sulphate or ferrous sulphate instead of aluminium sulphate. Other suitable similar compounds can also be used under necessary conditions. These compounds can be used either alone or with suitable mixtures thereof of.	A process for the production of rayon fibers. The viscose solution is spun into a spinbath which is acidic in character but has no zinc salt like conventional baths. The spin bath contains sulphuric acid, aluminum sulphate and sodium sulphate. The spinning is at temperatures of 35°-60° C. Usual stretching and post spinning operations are carried out as necessary. The regenerated cellulose fibers obtained are of novel cross-sections, namely of `c` cross section not achieved ever before. The fibers exhibit increased luster and softness.	3
BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a process for the production of a thin-layer system with a transparent silver layer by means of magnetron cathode sputtering, to a glass pane with transparent thin-layer system including a silver layer applied by magnetron cathode sputtering, and to a double glazing pane or unit (insulating unit) comprising such a pane. 2. Description of the Related Art Glass panes with thin-layer systems for the purpose of influencing their transmission and reflection properties are being employed in increasing numbers for the glazing of buildings and vehicles. Here, in practice, in addition to pyrolytically applied layer systems based on semi-conductive metal oxides, primarily layer systems with at least one transparent silver layer are of significance. These layer systems typically possess the following structure: glass/lower antireflection layer/silver layer/outer antireflection layer. They are applied widely on a major industrial scale by means of magnetron cathode sputtering (U.S. Pat. No. 4,166,018). In layer systems of this type, the silver layer serves mainly as an IR reflection layer, whilst the antireflection layers are employed specifically, through suitable selection of material and thickness, to influence the transmission and reflection properties in the visible region of the spectrum, according to application. It is generally endeavoured to provide the coated glass pane with a high light transmission factor, as well as maximum neutrality of colour in respect of transmission and external appearance. A development of this layer system consists of employing more than one silver layer, where between the individual silver layers, additional transparent spacing layers are provided. The silver layers and the spacing layers then form a type of Fabry and Pŕot interference filter. These multiple-silver-layer systems allow the specialist further improved “fine tuning” of the optical data of glass panes coated in this way. Layer systems with two or more silver layers are employed primarily as solar control coatings, where especially high selectivity is involved. Selectivity denotes the ratio of light transmission factor to total energy transmission factor. Thin-layer systems with only one silver layer are employed in practice primarily as large-area thermal insulation coatings which can be produced at relatively low cost, where importance is placed primarily on a high light transmission factor and a high reflection factor in the long-wave IR region, corresponding to low emissivity. From glass panes with such thin-layer systems it is possible, by combination with a normally uncoated second glass pane, to produce a thermal insulation glass which can be used primarily in the construction field, whose k value is 1.3 W/m 2 K or less. As materials for the antireflection layers, in the case of common market products, primarily metal oxides such as SnO 2 , ZnO and Bi 2 O 3 are used; these can be applied especially cost-effectively by means of magnetron cathode sputtering. Numerous other materials have already been designated for this purpose. When selecting the materials for the individual component layers of the thin-layer system, the coating specialist must take account of a considerable number of conditions. Thus, for the properties of the thin-layer system, not only the refractive indices of the individual component layers and their thickness play a significant part in selective regulation of the optical properties in respect of interference. The component layers also possess different properties in respect of refractive index, crystalline structure, crystallite size, roughness, porosity, surface energy, etc., according to the process with which they are applied and which component layer had been applied beforehand. As is known, the properties of thin layers, which frequently consist of only a few atomic layers, are determined very pronouncedly by the conditions of epitaxy and on their boundary areas. In the past, the specialist world has devoted special attention to improving the properties of silver layers. Silver layers are sensitive to a whole series of chemical and physical influences during the production of thin-layer systems, then during further processing and transportation of the coated glass panes, and finally during their use for the intended purpose. It is already known practice to protect the silver layer from the corrosive coating atmosphere during application of the outer antireflection layer of a Low-E thin-layer system by reactive cathode sputtering through application of thin metal or metal oxide layers (EP 0 104 870, EP 0 120 408). It is also known practice to protect silver layers from the influence of oxygen during heat treatment, for example during bending or tempering of glass panes by applying special auxiliary layers of greater thickness than that of the above-mentioned protective layers to the silver layer, which inhibit the diffusion of oxygen to the silver layer (EP 0 233 003). Both the first-mentioned protective layers and the last-mentioned auxiliary layers are preferably designed such that they are oxidised to the maximum extent in the finished product, so that they reduce the light transmission factor as little as possible and, as transparent dielectric layers, become component parts of the outer antireflection layers on the silver layers. It is also known that the corrosion resistance of the silver layer can be improved by suitable selection of the materials for the lower antireflection layer. DE 39 41 027 A1, from which the invention is derived as generic state-of-the-art, teaches in this connection that the lower antireflection layer be configured as a sandwich coating, where the component layer contiguous to the silver layer will have an zinc oxide layer with a maximum thickness of 15 nm. The lower antireflection layer should according to this publication possess at least one further component layer, for which tin oxide, titanium oxide, aluminium oxide and bismuth oxide are named. Preferred, and dealt with exclusively in the embodiments, is a layer structure, where the lower antireflection layer possesses three component layers, that is to say, a first 2-14 nm thick layer of titanium oxide, a second 15-25 nm thick layer of tin oxide, and as third, the zinc oxide layer mentioned, with a maximum thickness of 15 nm. Onto the contiguous silver layer is applied, according to this publication, an outer antireflection layer, which consists of a metal layer of specially selected metals, permitting bending or tempering while being oxidized during the course of heat treatment, as well as of one or more additional metal oxide layer(s). A similar structure is shown by EP 0 773 197, where the teaching is to be taken from this publication that to achieve a high level of light transmission and reduced emissivity, the zinc oxide layer contiguous to the silver layer is to be applied with a minimum thickness of 16 nm. As materials for at least one further layer of the lower antireflection layer, metal oxides, such as bismuth oxide, tin oxide or silicon nitride, are named. Both publications teach the application of the single layers required by means of conventional magnetron cathode sputtering, where metal targets are sputtered by application of a DC voltage (DC cathode sputtering). SUMMARY OF THE INVENTION The inventors have thoroughly investigated these and other previously known thin-layer systems and have found that they may be further improved in respect of the properties attainable. They have concerned themselves particularly with the problem that the transparent silver layers according to the state-of-the-art possess specific conductivity which is far below that which should be achievable for a defect-free silver layer of corresponding uniform thickness. This reduction in specific conductivity is especially apparent in the case of relatively thin silver layers. Thus, it was observed that in the case of thin-layer systems produced and constructed according to the state-of-the-art, measurable electrical conductivity only occurred at silver layer thicknesses of 4 nm or more, conductivity increasing with increasing layer thickness, but still remaining below the theoretically attainable value. For silver layers in the thickness range of 10-15 nm of especial interest for thermal insulation and solar control applications, it was possible at best to achieve specific conductivity values of approximately 2·10 5 S/cm with the known and conventionally produced layer structures. In order to obtain a specified electrical surface resistance or specified emissivity, the specialist had to employ significantly thicker silver layers than theoretically necessary. This led to problems in regulating the colour in external appearance and reduced the light transmission factor of the thin-layer system in an undesirable fashion. Of course, the state-of-the-art is acquainted with processes for subsequent improvement in the conductivity of silver layers, for example by means of heat treatment or irradiation (DE 42 39 355, DE 43 23 654, DE 44 12 318, EP 0 585 166). The use of these processes however increases the production costs for such products significantly and should if possible be avoided. The invention is based on the technical problem of improving the known thin-layer systems with at least one silver layer and their manufacture such that such silver layer possesses especially high specific conductivity and/or low emissivity. We have found that this may be achieved by sputtering the silver layer over a layer of titanium oxide deposited by medium frequency sputtering. According to one aspect of the present invention, there is provided a process for the production of a thin-layer system with a transparent silver layer by means of magnetron cathode sputtering, where between the substrate and the silver layer is arranged a multiple lower antireflection layer, which comprises a titanium oxide layer applied directly onto the substrate, as well as a zinc oxide layer contiguous to the silver layer, characterized by the fact that the 15-50 nm thick titanium oxide layer is applied by means of medium-frequency sputtering from two titanium cathodes in an oxygen-containing atmosphere onto the substrate and that the 2-18 nm thick zinc oxide layer is applied directly onto the titanium oxide layer. According to a further aspect of the invention, there is provided a glass pane with a transparent thin-layer system applied by means of magnetron cathode sputtering, the system consisting of a multiple lower antireflection layer, which comprises a titanium oxide layer directly on the glass pane, as well as a zinc oxide layer contiguous to the silver layer, a transparent silver layer, optionally at least one pair of layers consisting of a spacing layer and a further transparent silver layer, as well as an outer antireflection layer, characterized by the fact that the titanium oxide layer is a titanium oxide layer with a thickness of 15-50 nm applied by means of medium-frequency sputtering from two titanium cathodes in an oxygen-containing atmosphere, that the titanium oxide layer is directly contiguous to a zinc oxide layer with a thickness of 2-18 nm, and that the silver layer contiguous to the lower antireflection layer possesses a thickness of 7-20 nm. The invention further provides a process for coating glass with a coating comprising at least one silver layer and inner and outer antireflection layers by magnetron sputtering characterized in that the inner antireflection layer comprises a layer of titanium oxide applied by medium frequency sputtering. Using the present invention, it is possible to achieve a specific conductivity of at least 2.1×10 5 S/cm, and, in general, silver layers having a high electrical conductivity and hence low emissivity may be deposited. The invention further makes possible, as described hereafter, the deposition of as far as possible colour-neutral thin-layer systems for double-glazing panes with, in the case of thermal insulation applications, a high light transmission factor at specified emissivity or in the case of solar control applications with especially high selectivity, preferably a selectivity value of 2 or more. By appropriate use of the invention, such properties may be achieved without the use of subsequent heat treatment processes or other costly and time-consuming processes for aftertreatment of the thin-layer system Surprisingly, it is possible to provide silver layers with extremely high specific conductivity by using on the one hand, with the series of layers glass/titanium oxide/zinc oxide, a special twin lower antireflection layer and on the other hand the first of these component layers being produced by the use of the medium-frequency sputtering process. The specialist who was acquainted with the above-mentioned state-of-the-art could not expect that in fact this series of layers leads to such outstanding results in respect of the silver layer properties. As trials of the inventors showed, it is possible to achieve the most favourable values for specific conductivity of the silver layer with a multiple lower anti-reflection comprising a titanium oxide layer and a zinc oxide layer. Less favourable values are achieved with single lower antireflection layers of for example titanium oxide, tin oxide, zinc oxide or bismuth oxide, or other twin-layer structures. The use according to the invention of the medium-frequency sputtering process for production of the first component layer of titanium oxide leads to a further significant improvement in the silver-layer quality over conventionally applied titanium oxide layers. This is all the more surprising in that, in the case of the preferred layer structure according to the invention, between the titanium oxide layer and the silver layer thus applied, there is also a zinc oxide layer up to 18 nm thick, so that such a clear effect on the silver layer quality of the production technique for the first layer of titanium oxide applied to the glass pane could not be expected. It is surprising not only that the nature of the sputtering process used to deposit the titanium oxide has such an effect on the subsequently deposited silver layer, but that it does so even when an intervening metal oxide layer is used, and indeed the use of a zinc oxide layer over the titanium oxide layer leads to even better silver layer properties than operating with the titanium oxide layer deposited by the medium frequency sputtering process alone. The medium-frequency sputtering process is described for example in DD 252 205 and J.Vac.Sci.Technol. A 10(4), July/August 1992. It may be operated using a pair of magnetron cathodes with targets arranged in front, which generally both consist of the same material to be sputtered, the polarity of the cathodes changing periodically at a frequency in the kilohertz range. Within the scope of the invention, it is preferable to operate at a frequency of approximately 5-100 kHz, in particular 10-40 kHz. The medium-frequency sputtering process permits reactive application of the titanium oxide layer from two titanium targets at high coating rate, the use of this process evidently leading to a special microscopic structure and/or surface characteristic of the titanium oxide layer, which also finally affects the properties of the silver layer in the manner striven for. A zinc oxide layer over the titanium oxide layer is also produced preferably by medium-frequency sputtering, although it does however lie within the scope of this aspect of the invention to produce the zinc oxide layer by means of conventional DC cathode sputtering. Particularly favourable silver layer properties can be achieved by, instead of a pure titanium oxide layer, a nitrogenous titanium oxide layer (sometime also called titanium oxide nitride layer), with a nitrogen content N/(N+O) in the layer of 5-50 atomic percent being applied in an coating atmosphere containing argon, nitrogen and oxygen. It is preferable to proceed such that the nitrogenous titanium oxide layer is applied in an atmosphere containing argon and nitrogen in the quantitative proportion of 3:1 to 1:5, as well as oxygen. The addition of nitrogen to the coating atmosphere during application of the titanium oxide layer permits not only operation at an increased coating rate, but also improves the quality of the subsequently applied silver layer. The nitrogen content of the coating atmosphere is preferably limited upwards such that the nitrogenous titanium oxide layer produced not yet possesses any significant absorption in the visible region of the spectrum, as can be observed in the case of pure titanium nitride layers. The oxygen content of the coating atmosphere is adjusted such that adequate oxygen is available for oxidation of the titanium and that the coating rate is as high as possible. Where, in connection with the invention, in order to simplify the terminology titanium oxide layers are mentioned, regularly nitrogenous titanium oxide layers will be included, unless pure titanium oxide layers are expressly referred to. The process for application of the titanium oxide layer should be conducted such that a coating rate of at least 30 nm/min, preferably over 50 nm/min is reached. By coating rate is meant the epitaxial rate on the glass substrate. The level of the coating rate clearly has an effect on the microscopic properties of the titanium oxide layer, higher coating rates for the titanium oxide tending to lead to improved properties of the silver layer. Especially preferred glass panes according to the invention are distinguished by the fact that the first layer of the lower antireflection layer is a preferably nitrogenous titanium oxide layer with a thickness of 15-50 nm, applied to the glass pane by the use of the medium-frequency sputtering process, that directly contiguous to the titanium oxide layer is a zinc oxide layer with a thickness of 2-18 nm, and that the silver layer possesses a thickness of 7-20 nm. The thickness of the titanium oxide layer is preferably between 18 and 40 nm, the thickness of the zinc oxide layer is preferably between 4 and 12 nm, and the thickness of the silver layer is preferably between 8 and 15 nm. It has been found advantageous for provision of the complete thin-layer system if the outer antireflection layer consists of a 2-5 nm thick protective layer of an oxide of one of the metals In, Sn, Cr, Ni, Zn, Ta, Nb, Zr, Hf, in particular of In(90)Sn(10)-oxide, as well as of an outer layer of a material selected from the oxides of Sn, Zn, Ti, Nb, Zr and/or Hf and silicon nitride, in particular of SnO 2 with an optical thickness of 60-120 nm, preferably 80-100 nm. It can be preferable, especially for solar control layer systems if, between the silver layer contiguous to the lower antireflection layer and the outer antireflection layer, at least one pair of layers is provided, consisting of a spacing layer and a further silver layer. With such layer systems, it is possible by optimizing the layer thicknesses of the individual layers, to achieve combinations not previously considered possible of the values for light transmission factor, emissivity and neutrality of external appearance. Of course, application of the invention is not restricted to the use of inorganic glass panes, in particular float glass panes. By glass panes within the scope of the invention are meant all transparent panes of inorganic or organic vitreous material. It lies within the scope of the invention to add to the individual layers of the thin-layer system small quantities of other materials in order to improve their chemical or physical properties, as long as no significant decrease in the specific conductivity of the silver layer is caused thereby. In particular, it lies within the scope of the invention to use, instead of pure metal oxides, nitrogenous metal oxide layers for the oxide component layers used. The invention includes double-glazing panes with a glass pane coated according to the invention, especially thermal insulation double-glazing panes which, with a glass thickness of 4 mm of the two single glass panes, an argon gas filling, an interspace of 16 mm, as well as in the case of arrangement of the thin-layer system on the surface of the interior glass pane facing the interspace, a light transmission factor of at least 76%, a k value of maximum 1.1 W/m 2 K, an emissivity of maximum 0.04, and as colour coordinates of external appearance values of a* between −2 and +1, and b* of between −6 and −2. BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in detail below with the aid of Figures and examples. These show the following: FIG. 1 a graphical representation of the characteristic of the specific conductivity of a layer system of titanium oxide, zinc oxide and silver as a function of the thickness of the silver layer, FIG. 2 a graphical representation of the characteristic of the electrical resistance of a layer system in accordance with FIG. 1 with constant silver layer thickness as a function of the thickness of the zinc oxide layer, FIG. 3 a graphical representation of the characteristic of reflection and transmission factor between 400 and 2500 nm for a glass pane with a thermal insulation layer system according to the invention, FIG. 4 a graphical representation in accordance with FIG. 3 for a glass pane with a solar control layer system according to the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 reproduces the characteristic of specific conductivity of a silver layer for various layer thicknesses for arrangement of the silver layer on two differently produced lower antireflection layers. The continuous curve shows the characteristic of specific conductivity for the lower antireflection layer consisting of a titanium oxide layer produced according to the invention which has been applied to the glass pane by means of the medium-frequency sputtering process, as well as of a layer of zinc oxide contiguous to the silver layer and to the titanium oxide layer. Even from a thickness of approximately 3.5 nm, measurable conductivity is evident. For thicker silver layers, the value of specific conductivity approaches a limit value of approximately 3.5·10 5 S/cm. The broken line FIG. 1 reproduces the characteristic of specific conductivity for a comparative example where the titanium oxide layer has been produced by means of the conventional technology of DC cathode sputtering. In this case, a measurable conductivity only commences from a layer thickness of more than 4.0 nm. For thicker silver layers, a limit value of only 2.5·10 5 S/cm is obtained, that is to say one third below the value which is achieved according to the invention. The cause of this surprisingly high specific conductivity of the silver layer produced according to the invention presumably lies in the especially favourable epitaxy conditions for the silver which have been created by the lower antireflection layer produced according to the invention. The trials of the inventor indicate that best results may be achieved by appropriate selection of the materials for the two component layers of the lower antireflection layer, as well as the special production process for the titanium oxide layer. In the case of the medium-frequency sputtering process using double-cathodes, the rate of coating for titanium oxide can be significantly higher that with the conventional DC cathode sputtering. Presumably, as a result of the increased rate of coating and altered coating conditions associated with the use of this special sputtering process, the layer structure of the titanium oxide layer, and thus indirectly the silver layer, is influenced in the desired manner. The fact that not only the process of production of the titanium oxide layer according to the invention is important if the highest quality silver layers are to be produced, is illustrated by FIG. 2 . This Figure reproduces the characteristic of electrical resistance (in arbitrary units) of a silver layer with a thickness of 12.5 nm deposited on a lower antireflection layer consisting of a 25 nm thick titanium oxide layer and a zinc oxide layer. The representation of this Figure is based on a series of trials, where the thickness of the silver layer and the thickness of the titanium oxide layer have each been kept constant whilst the thickness of the zinc oxide layer has been varied. The continuous curve reproduces the values of electrical resistance for a lower antireflection layer with a titanium oxide layer which had been created by the medium-frequency sputtering process. The broken line shows the values for a titanium oxide layer which had been produced by the conventional DC cathode sputtering process. It can be seen first of all that the values for the titanium oxide layer produced according to the invention are clearly, that is to say by up to 10%, below those for a titanium oxide layer applied conventionally. In addition, it becomes clear that for the electrical resistance, a distinct minimum is obtained with a thickness of the zinc oxide layer of approximately 8 nm in the case of the layer according to the invention, the resistance being between approximately 2 nm and 18 nm below the values attainable with conventional technology. The production process according to the invention and the coated glass panes producible with it are illustrated below with the aid of examples. EXAMPLE 1 Onto a 4 mm thick float glass pane of soda lime silicate glass with the dimensions 40×40 cm 2 , a 25 nm thick titanium oxide layer was applied initially in a vacuum chamber with a medium-frequency double-cathode arrangement. For this purpose, an Ar/N 2 /O 2 mixture in a volume ratio of 12:8:3 was introduced into the chamber, so that a pressure of 2.2·10 −3 mbar was obtained. The output of the double-cathode was 8.4 kW, the alternating frequency of the voltage was 25 kHz. Onto the titanium oxide layer was subsequently applied with the aid of a DC cathode an 8 nm thick zinc oxide layer. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 2.4·10 −3 mbar was obtained. The output of the cathode was 4.1 kW. Finally, a 12.5 nm thick silver layer was applied. For this purpose, argon was introduced into the chamber, so that a pressure of 1.4·10 −3 mbar was obtained. The output of the cathode was 1.4 kW. The glass pane coated thus had on the coated side a surface resistance of 2.9Ω and an IR reflection factor of 97% at 8 μm. The specific conductivity of the silver layer was 2.75·10 5 S/cm. COMPARATIVE EXAMPLE 2 Onto a glass pane according to Example 1, a 25 nm thick titanium oxide layer was applied initially with a medium-frequency double-cathode in a vacuum chamber. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 2.1·10 −3 mbar was obtained. The output of the cathode was 8.8 kW, the alternating frequency of the voltage was 25 kHz. Onto the titanium oxide layer—at variance from Example 1—a silver layer was applied directly. For this purpose, argon was introduced into the chamber, so that a pressure of 1.4·10 −3 mbar was obtained. The output of the cathode was 1.4 kW. The thickness of the silver layer was, as in the first Example, 12.5 nm. The glass pane coated thus had on the coated side a surface resistance of 3.9Ω and an IR reflection factor of 96.2% at 8 μm. The specific conductivity of the silver layer was 2.0·10 5 S/cm, and was thus nearly 30% below that of the layer produced according to the invention according to Example 1. COMPARATIVE EXAMPLE 3 Onto a glass pane according to Example 1, a 20 nm thick zinc oxide layer was applied initially, directly, in a vacuum chamber. For this purpose, an Ar/O 2 mixture was introduced into the chamber, so that a pressure of 2.4·10 −3 mbar was obtained. The output, of the cathode was 4.1 kW. Onto the zinc oxide layer was directly applied a 13.0 nm thick silver layer. For this purpose, argon was introduced into the chamber, so that a pressure of 1.4·10 −3 mbar was obtained. The output of the cathode was 1.4 kW. The glass pane coated thus had on the coated side a surface resistance of 3.6Ω and an IR reflection factor of 96.6% at 8 μm. The specific conductivity of the silver layer was 2.1·10 5 S/cm, and was thus nearly one quarter below that of the layer according to Example 1 produced according to the invention. COMPARATIVE EXAMPLE 4 Onto a glass pane according to Example 1, a 25 nm thick titanium oxide layer was applied by means of a conventional DC cathode. For this purpose, an Ar/N 2 /O 2 gas mixture in the proportions of 3:10:2 was introduced into the chamber, so that a pressure of 5.0·10 −3 mbar was obtained. The output of the cathode was 10.0 kW. Onto the titanium oxide layer was subsequently applied an 8 nm thick zinc oxide layer. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 6.8·10 −3 mbar was obtained. The output of the cathode was 8.3 kW. Finally, a 12.6 nm thick silver layer was applied. For this purpose, argon was introduced into the chamber, so that a pressure of 1.4·10 −3 mbar was obtained. The output of the cathode was 1.8 kW. The glass pane coated thus had on the coated side a surface resistance of 3.8Ω and an IR reflection factor of 96% at 8 μm. The specific conductivity of the silver layer was 2.1·10 5 S/cm, and was thus nearly one quarter below that of the silver layer according to the first Example. Examples 1-4 show that by using the antireflection layer constructed and produced according to the invention, it was possible to achieve a surface resistance of the silver layer of less than 3Ω with a layer thickness of approximately 12.5-13 nn. The specific conductivity) of the silver layer was in all three Comparative Examples clearly below that of the layer produced according to the invention. This means, on account of the known relationships between electrical conductivity of the silver layer and its emissivity or IR reflection factor, that with a silver layer of specified thickness and thus upwardly limited light transmission, it is possible with the invention to achieve an especially high IR reflection factor and thus an especially low emissivity. The advantageous effects of the invention for practical applications become especially clear in connection with the description of the following two examples of production of glass panes with complete thin-layer systems. These possess, in addition to the basic structure according to Example 1, at least one outer antireflection layer, as well as optionally at least one further silver layer, separated from the first by means of a spacing layer. The data for emissivity and for the k value are based on the calculation methods of ISO Standard 10292. For determination of the light transmission factor and the total energy transmission factor, reference was made to ISO Standard 9050, whilst the coordinates a* and b* were determined according to DIN 6174. EXAMPLE 5 In order to obtain a thermal insulation coating with high reflectance in the long-wave IR region suitable for the production of a high-efficiency, highly light-transmitting thermal insulation double-glazing pane, a magnetron cathode sputtering system was used initially to apply onto a 4 mm thick glass pane with the dimensions 40×40 cm 2 , a 22.9 nm thick titanium oxide layer with the aid of a medium-frequency double-cathode. For this purpose, an Ar/N 2 /O 2 gas mixture in the proportion of 6:20:3 was introduced into the chamber, so that a pressure of 2.6·10 −3 mbar was obtained. The cathode output was 8.4 kW, the alternating frequency of the voltage was 25 kHz. The rate of coating for the titanium oxide layer was 50 nm/in. Subsequently, a 5 nm thick zinc oxide layer was applied onto the titanium oxide layer by means of a DC cathode. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 2.4·10 −3 mbar was obtained. The output of the cathode was 4.1 kW. Subsequently, an 11.8 nm thick silver layer was applied. For this purpose, the argon was introduced into the chamber, so that a pressure of 1.4·10 −3 mbar was obtained. The output of the cathode was 1.4 kW. Onto the silver layer was first applied a 3 nm thick In(90)Sn(10) layer as protective layer for the subsequent reactive application of the outer antireflection layer. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 2.4·10 −3 was obtained. The output of the cathode was 0.7 kW. As principal layer of the outer antireflection layer, a 44.8 nm thick tin oxide layer was finally applied. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 4.4·10 −3 mbar was obtained. The output of the cathode was 4.7 kW. The glass pane coated thus had as single pane a light transmission factor of 84.8%. The emissivity on the coated side was 0.04. The coated glass pane was with the coated side facing the interspace assembled with a second 4 mm thick uncoated float glass pane to form a thermal insulation double-glazing pane with an interspace distance of 16 mm and an argon gas filling. In the case of the arrangement of the coated glass pane on the inside (thin-layer system at Position 3), the double-glazing pane had a light transmission factor of 76.3% and a k value of 1.1 W/m 2 K. The spectrum locus of external reflection was defined by the colour coordinates a=−0.1 and b=−4.4. The external appearance of the thermal insulation double-glazing pane was thus almost neutral in colour. The spectral characteristic of the transmission factor of the coated single glass pane in the spectral range and in the near IR region is shown in FIG. 3 as a continuous curve. The characteristic of the reflection factor of the coating on the coated side is reproduced in broken line. EXAMPLE 6 In order to obtain a protective coating suitable for production of a solar control double-glazing pane with high selectivity (ratio of light transmission factor to total energy transmission factor), a magnetron cathode sputtering system was used first of all to deposit on a 6 mm thick float glass pane with the dimensions 40×40 cm 2 , 31.8 nm thick titanium oxide layer with the aid of a medium-frequency double-cathode. For this purpose, an Ar/N 2 /O 2 gas mixture in the proportions of 12:8:3 was introduced into the chamber, so that a pressure of 2.2·10 −3 mbar was obtained. The output of the cathode was 8.4 kW, the frequency of the voltage being 25 kHz. Subsequently, a 5 nm thick zinc oxide layer was applied. For this. purpose, an Ar/O 2 mixture was introduced into the chamber, so that a pressure of 2.4·10 −3 was obtained. The output of the cathode was 4.1 kW. There followed an 11 nm thick first silver layer. For this purpose, argon was introduced into the chamber, so that a pressure of 1.4·10 −3 mbar was obtained. The output of the cathode was 1.4 kW. Onto the first silver layer was applied a 3 nm thick In(90)Sn(10) layer as protective layer. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 2.4·10 −3 was obtained. The output of the cathode was 0.7 kW. Then, an 84.9 nm thick tin oxide layer serving as spacing layer for the subsequent second silver layer was applied. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure of 4.4·10 −3 was obtained. The output of the cathode was 4.7 kW. Onto this SnO 2 spacing layer was applied a second 14 nm thick silver layer. For this purpose, argon was introduced into the chamber, so that a pressure of 1.4·10 −3 was obtained. The output of the cathode was 1.4 kW. Onto the second silver layer was applied, as onto the first silver layer, and with the same process parameters, a 3 nm thick In(90)Sn(10) oxide layer. Finally, as principal layer of the outer antireflection layer, a 37.8 nm thick tin oxide layer was applied. For this purpose, an Ar/O 2 gas mixture was introduced into the chamber, so that a pressure 4.4·10 −3 mbar was obtained. The output of the cathode was 4.7 kW. The glass pane coated thus had as single pane a light transmission factor of 79.6%. It was assembled with another, uncoated float glass pane of thickness 6 mm to form a solar control double-glazing pane with an interspace distance of 16 mm and an argon gas filling. With arrangement of the thin-layer system on the inside of the outer pane (Position 2), a light transmission factor of 71.0% and a total energy transmission factor (g value) of 35.2% were obtained. Thus, an unusually high selectivity value of 2.02 was obtained for this solar control double-glazing pane. The external appearance, with the reflection colour coordinates of a=−0.3 and b=−1.15, was extremely colour neutral. The spectral characteristic of the transmission factor of the coated single glass pane in the visible spectral range and in the near IR region is represented in FIG. 4 as a continuous curve. The characteristic of the reflection factor in respect of the coated side is represented in broken line. The use of the invention is not restricted to constructions of Examples 5 and 6. These serve rather as examples of what properties of end products can be achieved by applying the teaching of the invention.	A glass sheet includes a coating comprising at least one silver layer and inner and outer antireflection layers. The glass sheet is formed by a magnetron sputtering process. The inner antireflection layer is a multiple layer comprising a layer of a titanium oxide applied by medium frequency magnetron sputtering and a layer of a metal oxide between the titanium oxide layer and a silver layer.	8
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit and priority of Great Britain Patent Application No. 1210974.0 filed Jun. 20, 2012. The entire disclosure of the above application is incorporated herein by reference. FIELD [0002] This invention relates to a method and system for managing recovery of control in an electrical system. The invention is particularly, though not exclusively, applicable to an inverter and a method and system for recovery of control in the event of an electrical transient in a renewable energy system. BACKGROUND [0003] An inverter is a form of converter of electrical energy. For example, the inverter can be arranged as part of a system for controlling the flow of power between a d.c. power supply and an a.c. power system. An inverter will typically comprise a bank of power switching devices, such as insulated gate bipolar transistors (IGBT's) and their anti-parallel diodes. The inverter is controlled by a microprocessor-based control unit which implements a control algorithm for the inverter. For example, power supplied from photovoltaic (PV) panels is fed to an a.c. power system such as an electrical grid network through an inverter that converts the d.c. output of the PV panels into a.c. power for the grid. In a particular application where the d.c. connections of an additional inverter supplying a motor are connected to create a drive that allows bidirectional power flow. [0004] Inductors are arranged between the inverter phase outputs and the a.c. power system to limit the harmonic currents that would be created due to the switching operation of the inverter. An additional switching frequency filter is often present as well to limit the harmonic voltage distortion to an acceptable level at the point of connection with the a.c. power network. [0005] Transient voltage changes can occur in an a.c. power system for various reasons, such as faults or the sudden connection of addition of equipment to the system. The inductors serve to limit the resulting transient current flowing between the a.c. power system and the inverter. An over-current protection system is usually provided to disable the switching devices in the inverter if the current flowing through the inverter exceeds a specific level above which the inverter may be damaged. A sufficiently large voltage transient in the a.c. power system may produce a current transient that is large enough to trigger the over-current protection system. However, disabling an inverter is seen as a last resort due to the time taken for the inverter to resynchronise itself to the supply and then undergo a restart procedure. It is not usually practicable to significantly increase the control bandwidth of the inverter control system to limit current transients so that the over-current trip is not activated with all possible voltage transients, and so the method conventionally used to ensure that the inverter remains active during a voltage transient in the a.c. supply is to increase the inductance between the a.c. supply and the inverter. In this way the transient current between the a.c. supply and the inverter can be limited, even with the worst case supply voltage transient, so that the over-current protection system is not activated except in the most severe of circumstances, such as a fault within the inverter system . Nevertheless, the impedance required to achieve this is larger than would be required for normal inverter operation. Large inductances are both bulky and expensive, and to be avoided if at all possible. SUMMARY [0006] An invention is set out in the claims. [0007] A method of managing recovery from an event in an electrical circuit leading to a loss of control of an inverter in the electrical circuit, the method comprising: sampling a parameter of operation before the event; monitoring for occurrence of the event; calculating an estimated value of the parameter at a time after the event based on an extrapolation of the monitored parameter; and controlling the inverter using the estimated value of the parameter. [0008] There is also disclosed a system for managing recovery from an event in an electrical circuit leading to a loss of control of an inverter in the electrical circuit, the system comprising: means for sampling a parameter of operation before the event; means monitoring for occurrence of the event; means for calculating an estimated value of the parameter at a time after the event based on an extrapolation of the monitored parameter; and means for controlling the inverter using the estimated value of the parameter. [0009] The monitored event may be a transient in the current in the circuit which is sufficient to trigger the over-current protection system. It has been recognised by the inventor that disabling an inverter temporarily is not necessarily a bad thing as long as the negative consequences of the disablement (e.g. downtime) can be addressed. While certain regulatory bodies permit an inverter system to trip out in normal operation, the disablement should be limited to a short period, such as 20 ms. Hence the preferred option has in the past been to avoid disabling the inverter by the use of large inductors. [0010] The parameter may be sampled and stored for multiple sample periods before the event. [0011] The estimated value of the parameter may be based on the parameter from one or more sample periods. [0012] In the particular form the sampled parameter is related to the phase angle of the alternating supply voltages of the circuit. In this case the estimated value of the parameter may be derived from an estimate of a reference frame angle controlling a three phase alternating current from the inverter. For example, the parameter in a first sample period may be used to produce the estimated value as an angle of the voltages, and the parameter in a second sample period used with the parameter from the first sample period to derive an estimate of the frequency of the voltages for synchronising the control of the inverter to the supply. [0013] In a particular application the circuit may comprise a d.c. source connected to one side of the inverter, for example a renewable energy source such as a photovoltaic array. The circuit may further comprise an additional inverter connected to a motor to create a drive that allows bi-directional power flow with the a.c. supply. [0014] In order to minimise the effect of possible transients in the resumption of control of the inverter the voltage demand to the inverter coincident with the estimated value of the parameter can be set at a non-zero value less than the voltage before the event, for example half the voltage before the event, thereby limiting the effect of any mismatch the voltage at resumption. [0015] The disclosed embodiments enable the use of inductors for normal inverter operation in an inverter power system by enabling the system to be restored to normal operation from a fault condition more quickly by having monitored the supply conditions before the disablement is required and using this information after the inverter has been disabled to predict the operating conditions that will prevail when the inverter is restarted. This saves time in the restart process. Thus, temporarily shutting down the inverter when an a.c. supply transient occurs can be accommodated within the operating function of the control system. DRAWINGS [0016] Embodiments will now be described by way of example with reference to the accompanying drawings in which: [0017] FIG. 1 illustrates an inverter; [0018] FIG. 2 illustrates an inverter system; [0019] FIG. 3 illustrates a reference frame based current controller for an inverter system; [0020] FIG. 4 illustrates a frame reference extrapolation time line; and [0021] FIG. 5 is a flow chart of the operation of part of the disclosed embodiment. DETAILED DESCRIPTION [0022] FIG. 1 is a typical arrangement of IGBT switching devices and anti-parallel diodes in an inverter. FIG. 2 is a typical arrangement of an inverter 10 used to connect a d.c. power source, such as a PV array 12 , connected to an a.c. power system, such as a grid network. The three phase a.c. side of the inverter is connected to the a.c. power system through an inductor 14 in each phase and a switching frequency filter 16 . [0023] FIG. 3 illustrates a system for controlling the currents and providing over-current protection in an electrical system such as that illustrated in FIG. 2 . The system is typically implemented with digital electronics including a microprocessor programmed to implement a suitable control strategy. The implementation of the disclosed embodiments is described in terms of functional block diagrams of the digital electronics and controlling software provided by the microprocessor. In this particular example the control strategy is based on PI controllers. Other control algorithms are also utilisable. The disclosed methods and systems can be implemented in other hardware control systems. [0024] The system comprises an inverter 10 providing a three phase output through the inductors 14 and filter 16 . The system is based on PI functions 17 / 18 providing orthogonal d.c. voltage signal components V x and V y to a rectangular-to-polar converter 20 having an output of voltage magnitude V and voltage angle θ v . The normalised voltage signal is then used as one input to a space vector modulator (SVM) 22 which implements an algorithm for control of the inverter to create a three-phase a.c. output. The other input to the SVM 22 is a modulation angle signal O. The system also comprises a phase locked loop (PLL) 24 which defines the reference frame angle, and in the steady state ties the voltage angle signal O to the y axis of the controller reference frame by a imposing a 90° displacement between the required voltage vector and the reference frame. The reference frame angle θ REF is summed with the voltage angle signal O to produce the modulation angle θ m . To ensure that the current controllers have consistent loop gains for different levels of d.c. voltage on the inverter terminals the voltage magnitude V is normalised with d.c. voltage level in normaliser 26 to give the modulation depth m for the SVM. The output of the SVM 22 is a set of control signals for the switching devices in each of the three phases of the inverter 10 . The function of the PLL 24 is well known to the skilled person. A full description of its function in the context of a voltage source pulse width modulated converter can be found in the paper “PWM rectifier using indirect voltage sensing” by P. Barrass and M. Cade, IEE Proc. Part B—Electrical Power Applications., Vol. 146, No. 5, September 1999, the entirety of which is incorporated herein by reference. [0025] Signals indicative of the three phase a.c. currents i u , i v , i w at the a.c. side of the inverter are produced by current transducers 28 - 32 and are fed back to a three phase/two phase converter 34 to produce two phase current signals i D and i Q , which are in turn transformed in transformer 35 into current components i x and i y in the reference frame defined by the reference frame angle θ REF . The current feedback signals of i x and i y are compared with the corresponding current demand signals i x * and i y * in comparators 36 and 38 and the difference signals are supplied to the PI functions 17 / 18 . Hence the system is designed to produce current components i x and i y to follow the reference values of current i x * and i y . [0026] The PI functions 17 / 18 include proportional and integral components. The integral components are more suited to the steady state control of the currents, whereas the proportional components provide transient control. In addition, the current transient limiting effect of the inductors between the a.c. power system and the inverter 10 is supplemented by the proportional components of the PI functions. The higher the gain of the proportional functions, the smaller the resulting current transient produced as a result of voltage transients in the a.c. power system. The inverter 10 has an over-current disabling system 40 which is not reliant on the control system processor for operation. The disabling over-current protection system 40 comprises threshold detectors 42 - 46 which monitor the current signals i u , i v , i w from the transducers 28 - 32 . In the event that a current in one or more of the phases reaches a threshold that is of a magnitude (either positive or negative) just below that which would damage the inverter, one or more of the detectors sends a signal to control logic 48 that rapidly disables the switching devices of the inverter to a non-conducting state. [0027] If disabling of the inverter according to previous practice is to be avoided then the combination of the inductors between the a.c. supply and the inverter, and the proportional gains of the PI functions, have to be such that any voltage transient could not cause the current to reach the threshold level set in the control logic 48 . In a known system this is compromised for two reasons. Firstly, there is a limit on the maximum gain of the proportional components above which the current control system will become unstable. The maximum gain is usually limited to a level by the presence of the switching frequency filter 14 . Secondly, for a given level of proportional gain the current transient could be limited by using a large inductance between the a.c. power system and the inverter. However, as explained this cannot be achieved without increasing the inductance to a value that is significantly larger than that normally required to limit the current harmonics due to the inverter switching action. Increasing the inductance to the required level is not commercially acceptable. [0028] It has been found that shutting down the inverter may be part of an acceptable solution to managing recovery from a transient or other event potentially damaging to the control system, and there are applications where it would be acceptable for the inverter actually to be disabled for a short period, provided it begins to operate again within this period. One example is in renewable energy applications, such as the PV application already mentioned. Typically, it can be a requirement that within 20 ms of a fault occurring in the a.c. power system that causes the a.c. voltage to fall to a low level, the inverter must deliver controlled active and reactive current again. According to the disclosed embodiments herein, the inverter over-current protection system is arranged to disable the inverter when a significant voltage transient occurs, but the system recovers within the required amount of time to enable both active and reactive current to be delivered even if the a.c. power system voltage is close to zero immediately after the fault. [0029] It is desirable that the control system ensures that the required fundamental levels of active and reactive current flow between the a.c. power system and the inverter. To do this the instantaneous phase of the a.c. power system voltages is used to provide the reference frame angle θ REF . The value of the voltage angle O is compared in the PLL 24 with 90° so that it will be 90° in normal operation. Hence the supply voltage is aligned with the y axis of the reference frame. The PLL 24 includes a PI function 50 giving an output of the required reference frame frequency F REF , and this output is integrated by integrator 52 to produce the reference frame angle θ REF . If the supply voltage is at or close to zero, or the inverter has been disabled because of an over-current event, the phase of the a.c. power system voltages cannot be obtained. However, the instantaneous phase and the steady state frequency of the a.c. power system voltages are available before the voltage transient occurred. This information can be extrapolated to estimate the phase angle of the a.c. power system voltages present after the fault, so that the correct active and reactive power can be delivered to the a.c. power system while the voltages are too low to be used to obtain the refrence frame angle θ REF . [0030] Operation of the circuit of FIG. 3 according to one form is as follows. [0031] Before the transient—in addition to the functions of the control system, the reference frame angle θ REF is sampled and stored by sample and store function 54 at a sample rate slower than that of the control system (e.g. once every second) to be used after the voltage transient to extrapolate the reference frame angle for the control system. The sampling system before, during and after a voltage transient is shown in FIG. 4 . It will be seen that the information available in the sample N is corrupted as a result of the voltage transient. [0032] Immediately after the transient at time t, if the over-current system 48 becomes active due to the detection of a current transient in one of the phases then the inverter 10 is disabled. For a short period the current that was flowing in the inductors will decay via the anti-parallel diodes_in the inverter. There will be no net power flow through the inverter during this period and the reference frame angle θ REF can no longer be obtained by monitoring the voltage angle θ v . [0033] Therefore, it is necessary to derive a value for the reference frame angle θ REF that is not available after N due to the voltage transient at time t. The integrator 52 that normally provides the reference frame angle θ REF is set up after the event at time t based on information taken before the voltage transient and is loaded with θ REF (N−2)+([θ REF (N− 2 )−θ REF (N−1)]×(2T+T N +t)/T), where t is the time since the voltage transient. This has used the available uncorrupted information to estimate the present reference frame angle that would still be substantially synchronised to the angle of the a.c. power system voltages assuming that the a.c. power system frequency has not changed significantly. Because the data used was obtained at least one sample period (T) before the voltage transient occurred, it is unaffected by the transient itself. From this point onwards the integrator 52 is fed with a derived value that will cause the estimated reference frame angle to continue to follow the angle of the a.c. power system voltages based on the change of reference frame angle between θ REF (N−2) and θ REF (N−1) again avoiding any data that could be affected by the voltage transient. [0034] Having derived an estimate of the value for θ REF and when the current in the inductors has decayed due to being disabled, the inverter is re-enabled and in this embodiment the values for the current references i x and i y * are set to zero. At this point the a.c. power system voltages are unknown. Any attempt to impose arbitrary values of voltages could result in a further voltage transient of an unacceptable magnitude. To minimise the consequent transient current that could occur due to a mismatch between the inverter voltages and the a.c. power system voltages when the inverter is re-enabled, the integrators in the current PI functions 17 / 18 are preset to a value equivalent to half the level likely to be present during normal operation. This value can be derived from the previous values based on monitoring previous power system activity. As the y component of the reference frame is normally aligned with the voltage vector produced by the a.c. power system voltages, the integrator for the y axis PI function 18 is set to half the likely supply voltage and the integrator for the x axis PI function 17 is set to zero. If this operation is successful then a short time later the inverter will be active and matching the a.c. power system voltages due to the control function based on the PI functions and so a minimal fundamental current will be flowing between the inverter and the a.c. power system. This form of the procedure is set out in the flow chart of FIG. 5 . [0035] The re-established current is detected in the transducers 28 - 32 and passed to the processor of the system. The current references can now be adjusted to demand the required amount of active and reactive current flow i x and i y between the a.c. power system and the inverter. The level of active power may be limited if the a.c. power system voltages are low otherwise excessive current will then be required to deliver any significant amount of power. [0036] Finally, the system reverts to normal reference frame measurement operation. [0037] Once the inverter is active again, the phase angle of the a.c. power system voltages can be obtained again by monitoring the voltage angle O at the output of the current PI functions 17 / 18 . This information can only be considered to be reliable if the a.c. power system voltages are reasonably balanced (ie. the three phase voltages are substantially equal) and above a defined threshold where the supply voltages are large enough to give reliable phase information. If the information is considered acceptable, the reference frame angle is obtained under the normal control conditions and the reference frame angle is again sampled at sample rate T to be used in the event of a subsequent voltage transient. [0038] If a voltage transient occurs in the system that does not cause the over-current protection system 48 to become active and the a.c. power system voltages remain above the level where the reference frame angle θ REF can be obtained by monitoring the voltage angle θ v then the above protection system is not used. However, if the over-current protection system does not become active, but the a.c. power system voltages are considered too low to be used to obtain the reference frame angle, then the reference frame angle information obtained before the voltage became too low can be used in a similar way to extrapolate the reference frame angle until the voltage is recovered sufficiently to be used again. Thus, the disclosed embodiments are applicable to situations where an inverter has been disabled and also when the voltage is insufficient to derive values for reliable control of the power. [0039] The disclosed embodiments are applicable to the control of an electrical system such as the delivery of electrical power from a renewable energy source, such as a PV array, to an electrical power network.	A method of managing recovery from an event in an electrical circuit leading to a loss of control of an inverter in the electrical circuit is disclosed, the method comprising sampling a parameter of operation before the event, monitoring for occurrence of the event, calculating an estimated value of the parameter at a time after the event based on an extrapolation of the monitored parameter and controlling the inverter using the estimated value of the parameter.	8
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates generally to heat transfer systems for co-generation units; and, more particularly, to heat transfer and cooling systems for internal combustion engine driven co-generation units. [0003] 2. Description of Related Art [0004] Electric energy generation in this country has lagged behind demand. There are a number of reasons for this, but chief among them is failure of traditional energy producers to replace spent units and capitalize new plants. This has been, in part, due to increased air quality regulations. In addition new challenges face electric generation security. Events of Sep. 11, 2001 showed this nation its vulnerability to terrorist attack. Vital operations, such as police, medical and civil defense that relied upon the electric power “grid” for service, realized that their needs were susceptible to disruption and viewed stand-alone units as well as micro grids as a possible solution. These alternatives are fraught with their own problems. Chief among the reasons is a drastic increase in demand. Thus, while energy demand has increased, generating capabilities have not. [0005] One reason for the growth in demand is the increased use of computers and other technology for industrial and business purposes, as well as personal use. As computer usage continues to grow, the use of power-consuming peripheral technologies, such as printers, cameras, copiers, photo processors, servers, and the like, keep pace and even expand. As business use of computer based equipment continues to rise, as do the number of in-house data servers, outsourced data storage facilities, financial systems, and Internet-related companies requiring constant electrical uptime and somewhat reducing traditional peak demand times, requirement for reliable, cheap, environmentally compliant electrical power continues to grow. [0006] Other technological advances have also increased electrical energy demand. Increased use of power consuming devices in every aspect of life from medical to industrial manufacturing robots, as well as innovations in almost every-research and industrial field are supported by increasingly complex technology, which requires more electrical power to function. CAT scans, NMRs, side looking X-rays, MRIs and the like all take electrical power. [0007] As a result, the Federal Government deregulated power generation, and a number of states have begun to establish competitive retail energy markets. Unfortunately, the deregulation process has not provided adequate incentives for industry entities to construct generating facilities, upgrade the transmission grid, or provide consumers with price signals to enable intelligent demand-side management of energy consumption. With the deregulation in the utility market, energy (kWh) has become a commodity item that can be bought or sold. However, swings in supply and demand leave end users open to fluctuations in the cost of electricity. [0008] According to the ETA, to meet projected increases in demand over the next 20 years, at least 393 GW of additional generating capacity must be added. In some areas, the growth in demand is much higher than the projected two percent average (e.g., California's peak electricity demand grew by 18 percent between 1993 and 1999, while generating capacity increased by only 0.3 percent.) Despite California's highly publicized energy situation, a similar problem exists for other states as well; the New York Independent System Operator recently stated that 8600 MW of additional generating capacity (a 25 percent increase) must be added by 2005 to avoid widespread shortages that may lead to blackouts. [0009] In addition to the mismatch between demand and generating capacity, the physical transmission infrastructure necessary to deliver power from geographically remote generating facilities to the consumer's location is unable to support the increased load. Even under today's operating conditions, the transmission grid is subject to stress and occasional failure. [0010] Additionally, security and reliability of source has become of increasing concern. Vulnerability of grid systems and blackouts have become more commonplace. Strategic industries are looking to cut energy costs, increase reliability, and assure security. This has lead to an interest in distributed market technologies. The potential market for distributed generation has become vast without adequate means for fulfilling this need. Again, inefficiency, reliability, and environmental concerns are major barriers. The compelling economics are made on engine efficiency without the financial benefit of waste heat usage, yet with all of the same customer reluctance to accept hassles. Industry estimates indicate that the existing market for distributed generation is $300 billion in the United States and $800 billion worldwide. [0011] The need to leverage existing technology while transitioning to alternative energy sources is an important driver for meeting this challenge. Although most existing distributed generation sites use small gas turbine or reciprocating engines for generation, there are many alternatives that are being considered over the longer term. Technologies, such as micro turbines, are currently available, but only used at a relatively small number of sites. These newer generators offer some inherent advantages, including built-in communications capabilities. It is anticipated that fuel cells will be available in the next five years, which will provide some highly appealing, environmentally friendly options. [0012] As it stands today however, small gas turbine and reciprocating engines comprise a substantial proportion of existing generator technology in the market and will for some time to come for a number of reasons. Engines provide the best conversion efficiency (40%), and they can operate using non-pressurized gas. Micro turbines, on the other hand, require compressed gas and conversion efficiency is lower (approximately 30%). These latter generators tend to be used in wastewater and landfill and other specialty sites, where a conventional prime mover is unable to stand up to poor fuel quality. Therefore, for utilities to truly benefit from a distributed generation scheme over the short term, they must look to the existing generator technology to provide a sustainable and affordable solution. [0013] Waste heat utilization or co-generation is one way to meet this challenge. In the case of power generation, the waste heat is not used, and the economics are based largely on the cost of the electricity produced (i.e. heat rate is paramount), with little consideration for improved reliability or independence from the electric grid. The anticipated fluctuation in energy costs, reduced reliability, and increasing demand has led end users to consider maximizing efficiency through use of heat from generation of on-site generating-heat capture systems, i.e. co-generation, or “Combined Heating and Power” (CHP). [0014] Co-generation of electricity and client process/utility service heat to provide space heating and/or hot water from the same unit is one solution. Co-generation provides both electricity and usable process or utility heat from the formerly wasted energy inherent in the electricity generating process. With co-generation, two problems are solved for the price of one. In either case, the electricity generation must meet stringent local air quality standards, which are typically much tougher than EPA (nation wide) standards. [0015] On-site co-generation represents a potentially valuable resource for utilities by way of distributed generation. A utility can increase capacity by turning to a “host” site (e.g. industrial user) with an existing generator, and allow them to parallel with the grid and use their generator capacity to handle peak volumes. From the utility's point of view, the key advantages to a distributed generation solution are twofold: improved system reliability and quality; and the ability to defer capital costs for a new transformer station. [0016] For customers who can use the process/utility waste heat, the economics of co-generation are compelling. The impediment to widespread use is reliability, convenience, and trouble-free operation. Co-generation products empower industrial and commercial entities to provide their own energy supply, thus meeting their demand requirements without relying on an increasingly inadequate public supply and infrastructure. [0017] Unfortunately, to date, the most widespread and cost-effective technologies for producing distributed generation and heat require burning hydrocarbon-based fuel. Other generating technologies are in use, including nuclear and hydroelectric energy, as well as alternative technologies such as solar, wind, and geothermal energy. However, burning hydrocarbon-based fuel remains the primary method of producing electricity. Unfortunately, the emissions associated with burning hydrocarbon fuels are generally considered damaging to the environment, and the Environmental Protection Agency has consistently tightened emissions standards for new power plants. Green house gases, as well as entrained and other combustion product pollutants, are environmental challenges faced by hydrocarbon-based units. [0018] Of the fossil fuels, natural gas is the least environmentally harmful. Most natural gas is primarily composed of methane and combinations of Carbon Dioxide, Nitrogen, Ethane, Propane, Iso-Butane, N-Butane, Iso-Pentane, N-Pentane, and Hexanes Plus. Natural gas has an extremely high octane number, approximately 130, thus allowing higher compression ratios and broad flammability limits. A problem with using natural gas is reduced power output when compared to gasoline, due mostly to the loss in volumetric efficiency with gaseous fuels. Another problem area is the emissions produced by these natural gas engines. Although, the emissions are potentially less than that of gasoline engines, these engines generally require some types of emissions controls such as exhaust gas re-circulation (EGR), positive crankcase ventilation (PCV), and/or unique three-way catalyst. A still another problem with using natural gas is the slow flame speed, which requires that the fuel be ignited substantially before top dead center (BTDC). In general, most internal combustion engines, running on gasoline, operate with a spark advance of approximately 35° F. BTDC; where as, the same engine operating on natural gas will require an approximate advance of 50° F. BTDC. The slower burn rate of the fuel results in reduced thermal efficiency and poor burns characteristics. Never the less natural gas fueled engines provide a valuable power source for distributed generation. [0019] Internal combustion engines utilized for combined heat and power are designed so that engine coolant from the radiator passes through a process/utility heat exchanger so the heat from combustion can be transferred to a co-generation client. Prior art co-generation systems employing internal combustion engines, and specifically, natural gas fueled engines have suffered from the myriad of problems including elevated head temperatures and inability to deliver large quantities of process and/or utility heat to the co-generation client. Excessive head temperatures lead to inefficient operation and unacceptable environmental conditions, which include excessive use of fuel as well as significant thermal NO x production. [0020] It is well known that emission reduction for natural gas engines can be accomplished by recycling of exhaust gases to make the engines “run lean.” Numerous systems have been devised to recycle exhaust gas into the fuel-air induction system of an internal combustion engine for the purposes of pre-heating the air-fuel mixture to facilitate its complete combustion in the combustion zone, for re-using the unignited or partially burned portions of the fuel which would otherwise pass to exhaust and into the atmosphere, and for reducing the oxides of nitrogen emitted from the exhaust system into the atmosphere. It has been found that approximately 15 to 20 percent exhaust gas recycling is required at moderate engine loads to substantially reduce the nitrogen oxide content of the exhaust gases discharged in the atmosphere, that is, to below about 1,000 parts per million. [0021] Although the prior art systems have had the desired effect of reducing nitrogen oxides in the exhaust by reducing the maximum combustion temperature as a consequence of diluting the fuel-air mixture with recycled exhaust gases during certain operating conditions of the engine, these systems have not been commercially acceptable from the standpoints of both cost and operating efficiency and have been complicated by the accumulation of gummy deposits which tend to clog the restricted bypass conduit provided for recycling the exhaust, and have also been complicated by the desirability of reducing the recycling during conditions of both engine idling when nitrogen oxide emission is a minor problem and wide open throttle when maximum power is required, while progressively increasing the recycling of exhaust gases with increasing engine load at part open throttle. [0022] The nitrogen oxide emission is a direct function of combustion temperature, and for that reason is less critical during engine idling when the rate of fuel combustion and the consequent combustion temperature are minimal but tends to be problematic during throttle up and extended full speed operation. In the usual hydrocarbon fuel type engine, fuel combustion can take place at about 1,200° F. The formation of nitrogen oxides does not become particularly objectionable until the combustion temperature exceeds about 2,200° F., but the usual engine combustion temperature, which increases with engine load or the rate of acceleration at any given speed frequently, rises to about 2,500° F. It is known that the recycling of at least one-twentieth and not more than one-fourth of the total exhaust gases through the engine, depending on the load or power demand, will reduce the combustion temperature to less than 2,200° F. Contaminants in the exhaust resulting from fuel additives desired for improved combustion characteristics normally exist in a gaseous state at combustion temperatures exceeding about 1,700° F., but tend to condense and leave a gummy residue that is particularly objectionable at the location of metering orifices and valve seats in the exhaust recycling or bypass conduit. [0023] Thus, natural gas fired internal combustion driven co-generation systems have previously suffered from one or more disadvantages. Specifically, the EGR system did not recycle exhaust gas to the intake engine manifold at sufficiently low temperature to foster low cylinder head temperatures. Simultaneously, turbo charged fuel systems, because of the compression, increased intake fuel manifold temperatures causing the same affect. Additionally, engine-cooling systems were not efficient enough to remove substantial engine heat from the cooling fluid while maintaining an inlet temperature of the coolant sufficient to reduce head temperatures to an acceptable level. This in turn reduced the heat, which was transferred to the co-generation client. However, increasing coolant flow through the engine increases parasitic load decreasing efficiency. The result was a rich burning engine, i.e. inefficient, with substantial thermal NO x production, violating air emission standards, while not providing sufficient heat transfer to the process/heat co-generation loop to be worthwhile. [0024] A further drawback was that recycling exhaust gas increased the intake air temperature and, therefore, increased the head temperature. This is particularly true when the inlet gas is supercharged. This combination of disadvantages made natural gas fueled, internal combustion driven co-generation systems an unacceptable candidate for client based distributed generation complexes. [0025] It would be, therefore, advantageous to have a system, which reduced fuel consumption, as well as NO x production while delivering substantial heat to the process/utility heat co-generation system. In addition, it would be advantageous to run a lean burning engine using recycled exhaust gas, which results in not only a lean burn but also reduced head temperatures leading to reduces thermal emissions and greater efficiency. SUMMARY OF THE INVENTION [0026] It has now been unexpectedly discovered that a system for engine cooling and effective heat transfer to a co-generation client, reduces engine head temperature thereby reducing fuel consumption and reducing pollutants, as well as delivering substantially increased heat to a co-generation process/utility heat facility. The cooling cycles and process/utility heat radiation configurations of the inventive system maintain cylinder inlet temperature resulting in improved efficiency, reduced thermal NO x and longer engine life. This allows operation of the engine at optimum inlet and outlet temperatures regardless of co-generation process/utility heat system requirements, without excessive parasitic pump loads. [0027] In accordance with the invention, a split flow engine cooling system includes a first coolant loop which directs coolant through the engine block, and a second loop which directs coolant through the at least one exhaust manifold in cooperation with the first loop, such that the coolant inlet temperature of the first loop is substantially reduced to maintain appropriate engine head temperatures to reduce thermal NO x while maintaining efficiency. The two loops then merge at a process heat exchanger such that the combined output heat contained in the liquid of the two loops is effective to deliver increased heat to the co-generation process/utility heat system without an increase in parasitic load, i.e. using the engine internal pump only. [0028] Advantageously, the coolant loops each carry different quantities of coolant to assure engine performance. In one embodiment, the loops can be balanced by means of a dynamic feed back valveing to assure head temperatures within a specified range. [0029] In accordance with another aspect of the instant invention, a turbo intercooler heat exchanger is used to reduce the temperature of compressed engine intake gas, emerging from the turbocharger, prior to its entry into the intake manifold of the engine such that the inlet gas temperature is reduced to retard the formation of thermal NO x . Thus the engine driven coolant pump can be utilized exclusively for the coolant loop, reducing the parasitic load, while drastically reducing cylinder inlet temperature resulting in improved efficiency, lower thermal NO x and longer engine life. [0030] In another aspect an EGR cooling circuit using air finned heat exchangers is used to reduce the temperature of the recycled exhaust gas, prior to its mixing with the intake gases for combustion. This further reduces cylinder inlet temperature resulting in improved efficiency, lower thermal NO x and longer engine life. [0031] In accordance with the invention a dump/balance radiator is used to remove heat not transferred to the co-generation process/utility heat system such that engine efficiency is maintained even in the absence of the co-generation process/utility heat system load. BRIEF DESCRIPTION OF THE DRAWINGS [0032] The following drawings form part of the present specification and are included to further demonstrate certain embodiments. These embodiments may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein. [0033] [0033]FIG. 1 is a flow chart of the heat transfer systems for co-generation of the instant invention; [0034] [0034]FIG. 2 is a flow chart of the engine cooling loop of the heat transfer systems for co-generation of the instant invention; [0035] [0035]FIG. 3 is a flow chart of the co-generation process/utility heat delivery loop of the instant invention; [0036] [0036]FIG. 4 is a flow chart of the turbocharger intercooler loop with turbo charged intake gas interface in accordance with the instant invention; and, [0037] [0037]FIG. 5 is a flow chart detail of the interface of the turbocharger intercooler radiator loop interface with the engine intake gas system and the engine exhaust system including the exhaust recycle in accordance with the instant invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0038] In accordance with the instant invention a natural gas fueled, internal combustion engine, employing exhaust gas recycle (EGR), delivers power to spin a coupled electric turbine, as well as heat of combustion, through a heat exchanger, to a co-generation process/utility heat loop for on site use as heat for process water, utility heat, space heat, potable hot water and the like. This is accomplished with the instant system by increasing the transfer of engine heat to the co-generation process/utility heat loop while maintaining the engine, and especially the head temperature low enough to increase efficiency and reduce thermal NO x to acceptable levels, even in the presence of the recycled exhaust gas. This is accomplished with substantially no increase in parasitic power requirements, such as adding external pumps to increase the flow through the heat exchanger. [0039] In accordance with the invention an engine coolant loop flow is split so that a first portion flows through the engine block, by way of the engine oil cooler, and through a thermal valve control to the fluid process heat exchanger. A second portion flows to at least one fluid cooled exhaust manifold by way of the engine oil cooler, for example, through the inlet ports of the left and right liquid cooled exhaust manifolds and then the inlet port of the fluid cooled turbocharger where it merges with the liquid from the first loop prior to going through the fluid process heat exchanger, which delivers heat to the co-generation process/utility heat system. [0040] Thus, in accordance with one embodiment, the coolant flows through a cooling loop by way of an engine driven pump through the oil heat exchanger. Exiting the oil heat exchanger it splits into two parallel loops. One loop follows a path through the engine block and the other through the coolant manifold, and then the coolant cooled turbo-charger. Both coolant flow loops converge at the thermal control valve where they blend back together to form a single stream prior to flowing through the fluid process heat exchanger. The thermal control valve senses the blended stream temperature and by-passes the fluid process heat exchanger if the temperature is below the threshold engine block inlet tempeture of, for example, 175° F. This closed loop prohibits flow through the fluid/process heat exchanger and dump/balance radiator to retard heat loss until optimum engine block inlet temperature is achieved. When the temperature is greater than, for example, 175° F., flow through the control valve is first diverted partially to the fluid/process heat exchanger and then fully to the fluid/process heat exchanger as operating temperatures are reached. [0041] The combined flow is, thus, through the coolant/process heat exchanger for use in heat exchange with the co-generation process/utility heat system. This parallel cooling loop increases the engine cooling loop heat available to the process/utility heat system, significantly, while maintaining favorable engine operating conditions. For example, the system of instant invention can maintain engine block outlet temperature of 198° F. instead of the typical 210° F. of comparable engine designs, while heat delivered to the process/utility co-generation system increased from a typical 780 , 000 BTU/hour to 1,100,000 BTU/hour. Flow through system is nominally 106 GPM with a differential of 20° F. across the engine block. In this manner the coolant through the second loop is at a higher tempeture, but a lower flow rate, while the coolant through the first is at a slightly lower tempeture, but a higher flow rate to keep the cylinder heads cooler, thus, increasing efficiency and reducing thermal NO x emissions. [0042] In accordance with a further aspect, the system employs a separate loop to cool supercharged engine inlet feed. This separation of the intercooler liquid coolant loop from the engine coolant loop provides a separate heat exchanger upstream of the engine intake manifold to reduce engine intake temperatures, drastically reducing head temperatures within the engine. Likewise, in a further aspect the exhaust recycle gas is cooled by at least one air cooled radiator prior to admixing it with air and fuel which is then compressed in the supercharger. [0043] The power source compatible with the instant invention is a natural gas fueled, internal combustion liquid cooled engine, wherein at least a portion of the exhaust gas is recycled to reduce NO x . For example a Deutz brand Engine Model BE 8 M 1015 GC engine manufactured by Deutz. The natural gas fired internal combustion engine is the prime mover of the electrical generation system, having liquid coolant flow system required return coolant at a temperature to the engine to reduce head temperature to less than about 1800° F. The internal engine pump moves the coolant through the various engine components and then through the process heat exchanger to transfer heat to the co-generation process/utility the system. [0044] Turning to the drawing, there is shown in FIG. 1, the system 10 , in accordance with the instant invention. An engine block 12 contains fluid cooling ports through which cooling fluid travels by means of internal fluid pump 14 located upstream of oil heat exchanger 16 , which is ideally housed within the engine. As shown, oil heat exchanger 16 is in fluid communication with the inlet port of engine block 12 by means of conduit 18 and with inlet of fluid cooled manifold 20 by means of conduit 22 . Preferably, oil heat exchanger 16 is contained within engine block 12 and is an integral part thereof. The outlet of engine block 12 communicates with the inlet of thermal control valve 24 by means of conduit 26 . [0045] The outlet of fluid cooled manifold 20 communicates with the inlet of fluid cooled turbocharger manifold 28 by means of conduit 30 . The outlet of fluid cooled turbocharger manifold 28 communicates with a second inlet of thermal control 24 through conduit 22 . In a bypass circuit for engine warm up, the outlet of thermal control valve 24 communicates through internal fluid pump 14 with oil heat exchanger 16 through conduit 34 . Alternately, during operation thermal control valve 24 communicates through internal fluid pump 14 with oil heat exchanger 16 by way of fluid process/heat exchanger 36 via conduit 38 and dump/balance radiator 40 via conduit 42 and then a T connect of conduit 44 with conduit 34 . [0046] As better seen in FIG. 2, this fluid loop comprises the coolant system 11 of the present invention. In operation, internal fluid pump 14 is driven by engine block 12 to flow coolant at a tempeture of about 175° F. and a flow rate of about 106 GPM through oil heat exchanger 16 and simultaneously through conduit 18 to the inlet of engine block 12 at a tempeture of about 182° F. and a flow rate of about 91 GPM and conduit 22 at a tempeture of about 182° F. and a flow rate of about 26 GPM to inlet of exhaust-cooled manifolds 21 . [0047] The exhaust-cooled manifolds 21 comprise the initial fluid cooled manifold 20 and the fluid cooled turbocharged manifold 28 as shown in FIG. 1., but can consist of one or more liquid cooled manifolds for removing heat from the engine exhaust. In accordance with the invention, these manifolds may comprise a single unit as shown in FIG. 2 or separate units shown in FIG. 1. The function of these manifolds is to cool exhaust and generate heat to the cooling fluid, which will be transferred to the co-generation client as described below. [0048] Coolant exiting from exhaust-cooled manifold 21 at a tempeture of about 210° F. and a flow rate of about 26 GPM, flows to thermal control valve 24 , which functions to limit fluid circulation back to inlet of the engine block 12 until operating temperature of the system is attained, and thereafter through conduit 38 to fluid process/heat exchanger 36 . Coolant exiting from engine block 12 at a tempeture of about 198° F. and a flow rate of about 91 GPM, flows to thermal control valve 24 where is merges with the coolant from exhaust-cooled manifold 21 . Dump/balance radiator 40 serves as a cooling radiator for the system to balance coolant inlet temperature to the oil heat exchanger 16 if fluid process/heat exchanger 36 removes insufficient heat or is turned off. [0049] Returning to FIG. 1, fluid process/heat exchanger 36 is a radiator which allows heat transfer from coolant system 11 (see FIG. 2) to co-generation process/utility heat system 13 , as seen in detail in FIG. 3. Co-generation process/utility system comprises a closed loop to circulate fluid, which is heated in fluid process/heat exchanger 36 , by means of pump 46 . Fluid process/heat exchanger 36 communicates with primary facility load 48 and secondary facility load 50 by means of conduit 52 and return conduit 54 . [0050] In operation, fluid process/heat exchanger 36 which contains coolant fluid at a tempeture of about 206° F. at a flow rate of about 106 GPM, provides heat exchange between coolant system 11 and co-generation process/utility heat system 13 , which provides heated liquid to the client in a co-generation configuration. Thus, the co-generation client receives transferred heat from the coolant system 11 by way of fluid process/heat exchanger 36 to the co-generation process/utility heat system 13 . The coolant in coolant system 11 is then heat balanced, if necessary, in the dump/balance radiator 40 to return through internal fluid pump 14 to oil heat exchanger 16 to loop at a tempeture of about 175° F. at a flow rate of about 106 GPM. [0051] Thus, for example heat in coolant flow, through the coolant/process heat exchanger, is captured for the co-generation client use by counter flowing process/utility water flowing through the coolant/process heat exchanger. Thermal regulating valves can be used to regulate process/utility water temperature to insure appropriate water temperature delivery to the co-generation use. [0052] In accordance with one aspect of the invention, an exhaust heat recovery silencer 56 , further cools the exhaust from the engine block 12 and communicates through client absorption chiller 58 by means of conduit 60 and return conduit 62 , as will be further described below in reference to FIG. 5. [0053] Turning to FIG. 4, a turbo intercooler cooling circuit is shown and its interface with recycled exhaust gas, fuel, and air. Turbo intercooler cooling circuit comprises a turbo intercooler 68 , which is cooled by coolant loop separate from coolant system 11 or process/utility heat system 13 and includes an intercooler radiator 70 fluidly communicating, via conduit 72 and pump 74 , in a continuous closed circuit, through intercooler coil 76 of turbo intercooler 68 . This fluid cooling system is dedicated to further reducing the inlet tempeture of the compressed fuel/air/exhaust gas mixture from the turbocharger 78 as further explained below. [0054] As better seen in FIG. 5, there are three operating systems associated with the intercooler radiator in accordance with the instant invention. FIG. 5 shows the interfaces between the turbo intercooler cooling circuit, the turbocharged, or compressed inlet gas mixture to the engine intake manifold and the recycled exhaust gas. This interaction is important in that head temperatures, gas inlet temperatures, and exhaust gas recycle temperatures can be tuned. [0055] As seen in FIG. 5, intercooler radiator 70 , pump 74 , and conduit 72 continually circulate coolant, in a closed loop, through coil 76 of turbo intercooler 68 as previously described and shown in FIG. 4. Ambient outside air passes through air filter 100 and intake conduit 102 to EGR venturi 104 , where air mixed with recycled exhaust gas from conduit 180 as will be more fully described. Mixed air and exhaust gas exists EGR venturi 104 through intake conduit 106 into fuel/air venturi 108 where the air exhaust gas mixture entrains fuel from a regulator (not shown). The fuel/air/exhaust gas mixture is compressed in turbocharger 78 via intake conduit 110 . The compressed fuel/air/recycled exhaust gas mixture exists turbocharger 78 through intake conduit 80 into turbo cooler 68 where it is cooled from 400° F. to 165° F. The cooled intake gas exists turbo intercooler 68 into engine intake manifold 112 and into engine cylinders 82 via conduit 84 . Exhaust gas from engine cylinders 82 exits into fluid cooled manifold 21 as previously described in FIG. 2 and enters turbocharger 78 through exhaust conduit 114 to power the turbocharger 78 , thus compressing the fuel/air/recycled exhaust gas mixture entering turbocharger 78 by means of intake conduit 110 as previously described. [0056] As can be seen, exhaust gas exiting turbocharger 78 is split into a recycled stream and an exhaust stream. The exhaust stream 116 enters three-way catalyst 118 and then exhaust heat recovery silencer 56 as previously described in connection with the description of FIG. 1. It will be realized, by one skilled in the art, that the exhaust heat recovery silencer 56 is on the co-generation process/utility heat system 13 and provides additional heat recovery for that system. [0057] A portion of the exhaust gas to be recycled passes through conduit 120 to primary air cooled EGR cooler 122 ; and, if necessary, secondary air cooled EGR cooler 124 by means of conduit 126 and then passes into EGR venturi 104 through conduit 180 as previously described. [0058] Thus, in accordance with the invention, ambient air (70° F.) flows through air filter to EGR venturi where it is mixed with up to 20% cooled exhaust gas (140° F.) at 100% load. The percent of recycled exhaust gas utilized is a function of engine load. This mixture (120° F.) then passes through the fuel/air venturi where fuel is drawn from a zero pressure gas regulator and mixed with the ambient air & exhaust gas to be flowed to the ambient side of the turbocharger. The fuel/air/recycle exhaust gas mixture is then pressurized by an exhaust gas-powered turbine to a pressure of 15 psig of at a temperature of (400° F.) This pressurized mixture passes through the turbocharger intercooler which reduces the pressurized and high temperature mixture to about 165° F. to be introduced into the intake manifold and then to the engine cylinders. [0059] Following combustion, exhaust gas from the cylinders (1100° F.) passes through the coolant-cooled manifolds to recover heat, which reduces the exhaust gas tempeture to about 940° F. The exit exhaust gas enters the exhaust (turbine driving section) of the turbocharger and, upon exiting, passes through a “T” with about 80% of the gas being flowed through a catalyst and a heat recovery silencer or muffler as previously described, and exhausted to atmosphere. A second portion comprising about 20% of the exhaust gas is passed through air coolers as previously described to the EGR venturi for introduction to the air/fuel intake system. The recycled exhaust gas is cooled by the air coolers to about 140° F. prior to admixing with air in the EGR venturi. [0060] The foregoing discussions, and examples, describe only specific embodiments of the present invention. It should be understood that a number of changes might be made, without departing from its essence. In this regard, it is intended that such changes—to the extent that they achieve substantially the same result, in substantially the same way —would still fall within the scope and spirit of the present invention.	A heat exchange cooling system for an internal combustion engine co-generation plant, which allows exhaust recycled gas combustion while maintaining lower head temperatures to reduce thermal NO x emissions while delivering increased process/utility heat to a proximate co-generation client, is provided. The cooling system has two cooling loops with different flow rates: one through the engine and the second through exhaust manifolds, such that higher engine block flow resulting in cooler head temperatures is provided, while allowing higher temperature coolant to flow through exhaust exchangers, such that when the two coolant flows converge at a process/utility heat exchanger for heating co-generation client liquid, the combined flows substantially increase the transferred heat. In another embodiment, a separate intercooler circuit is used to cool the compressed intake charge containing the recycled gas prior to entry into the intake engine manifold to further reduce head temperatures and control thermal NO x emissions.	5
BACKGROUND OF THE INVENTION This invention resides in the field of tools which use a magnet to position a workpiece such as a nut or bolt. More particularly, the present invention is a device which utilizes a spring in a socket to position and hold a nut or the like before assembly or after disassembly. The problem of positioning and retaining a fastening member such as a nut, bolt or the like is well known and has been present since the advent of the workpieces themselves, and particularly has been a problem with the socket type wrench. Fastening operations in most environments using a socket often necessitate manual placement of the nut or the like on the mating member such as the bolt stem, where such is possible, slowing assembly. In long-reach or constrained environments, manual placement may be difficult and may even expose the operators to hazards in some circumstances. Devices previous to my present invention which are directed to ejecting or holding a nut or the like are costly to machine and assemble, and do not easily and inexpensively afford the ability to adapt an existing deep-well socket to a nut-ejecting and positioning socket. U.S. Pat. No. 2,488,894, issued Nov. 22, 1949 to Barrett describes a magnetless device having a spring inside a machined retainer cage and mated plunger to eject a nut. U. S. Pat. No. 2,651,229, issued Sep. 8, 1953 to Lenz is directed to a magnetless two-piece driving tool having an internal spring bias. U.S. Pat. No. 2,676,506, issued Apr. 27, 1954 to Shultz describes a magnetless socket wrench comprising a mechanical bolt retaining mechanism. U.S. Pat. No. 2,720,804, issued Oct. 18, 1955 to Brown describes a tool having an elongated hollow member with a movable magnet having a bore therethrough within the hollow member. U.S. Patent No. 4,919,020, issued Apr. 24, 1990 to Huebachen describes a socket tool having a spring biased magnet assembly inside a hollow bore, wherein the spring is embedded in adhesive. None of the devices prior to my present invention meet the need for a functional, low cost assembly which may adapt a conventional socket to a magnetic nut ejecting socket. Such a tool is much desired. SUMMARY OF THE INVENTION It is the general object of my invention to provide an improved driving tool and socket which avoids the disadvantages and shortcomings of previously described tools, and which offers structural and operational advantages. It is an object of my invention to provide an insertable assembly for placement in a socket well which accomplishes the task of holding a nut, bolt or the like in position ready for fastening or following disconnection near the edge of the socket well. It is a further object of my invention to provide such a tool in a form that is economical to manufacture and assemble. In accordance with my present invention, I have overcome the deficiencies in prior devices and met the objectives described above. The device of my invention comprises a socket head coupled to a driving shank at one end of the socket head and a socket Well opening away from the shank cooperating therewith to receive a corresponding rotatable fastening member; a base disk having a top face and a bottom face; a flexible stem permanently attached to the base disk at a bottom stem-end and having an opposite top stem-end; a top disk having a stem face and a nut face concentrically positioned with and retained to the top stem-end; a magnet permanently affixed to the top disk on the nut face, and; a helical compression spring concentric with the stem abutting the top face of the base disk on one end and abutting the stem face of the top disk at the other end. In a preferred embodiment, the base disk and flexible stem assembly is molded from plastic, and has at the top end extending from the base disk a tip which is insertable through the top disk from the stem face through a central hole, retaining the top disk against the compression spring. Preferably, the tip is molded from plastic and is generally in the shape of a cone, but may be any shape which allows the tip to be inserted through and centrally positioned on the top disk. Preferably, the top disk is provided with a depression concentric with the central hole, for receiving the tip and avoiding the tip obstructing the flush mounting of a flat surfaced magnet. The preferred embodiment comprises holding means to detachably affix the base disk centrally in the base of the socket well. The magnet, stem and spring are selected in size and strength so as to consistently place the nut, bolthead or the like near the end of the socket for ease of removal from the driving tool. In the preferred embodiment, it is desirable to place the spring in compression during normal assembly to urge the straightening and full extension of the stem and further to maintain such position after repeated use of the driving tool. The tool of my present invention finds particular usefulness in manufacturing operations involving robotics. The unique design features result in the consistent placement of the workpiece at a known position following disassembly and consistent positioning of the magnet retaining means within the socket well, a necessity for robotic assembly. Among other factors, I have found the device of my invention to be substantially easier to manufacture and assemble than the spring and magnet devices described in the art. The cageless travel limiting stem, internal within the spring, provides a lighter and simpler device to brine and hold a workpiece at the socket edge. Surprisingly, I found the socket insert assembly of the driving tool of my invention to be easily adaptable to and easy to use with various sized commercially available sockets, and the cost of materials used in manufacturing the insert assembly to be surprisingly low. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts assembled socket insert in the normal position. FIG. 2 is an exploded view of a preferred deep-well embodiment of the socket insert, exposing the elements thereof. FIG. 3 shows in side cross-section the deep-well embodiment in operating position with magnetically-engaged nut in the normal position. FIG. 4 shows the deep-well socket and insert in the nut-driving position. DETAILED DESCRIPTION OF THE INVENTION By the term "socket", it is meant any form of generally cylindrical machined elements having a bore therethrough with one end machined on the interior to receive and impart a rotational driving force to a nut, bolt or the like with a nut-engaging portion; the other socket end adapted to receive a shank from a rachet or other driving mechanism. "Socket well" refers to the bore portion of the socket consisting of the nut-engaging portion and any portion of the bore between the nut engaging portion and the shank mating portion of the socket. By the term "fastening member", it is meant a nut, bolt or other rotatable element having a machine head or the like capable of being driven by a socket. FIG. 1 shows the assembled insert outside of the socket. Referring now to FIG. 2, where specific elements and features of my invention may be seen, the deep-well embodiment is depicted comprising a socket 1 with the top edge in view. In the exploded view diagram, the socket insert base disk 16 is sized in diameter to fit within the socket well abutting the base of the well. Base disk 16 is preferably completely circular. Flexible stem 5 is permanently affixed at the center of the top side of base disk 16 perpendicular thereto. Preferably, base disk 16 and flexible stem 5 are formed from a thermoplastic in an injection molding process of the kind well known in the art. Stem 5 is sized in diameter to allow the stem to deform in response to a force exerted upon top stem-end in the direction of the base disk 16, as will be further detailed below with reference to FIG. 3 and FIG. 4. Still referring to FIG. 2, compression spring 4 is positioned concentric with flexible stem 5. Preferably, spring 4 is a metal helical compression spring which maintains a substantially constant diameter during compression. Physical properties of commonly used spring materials useful in my invention are given in Handbook of Mechanical Spring Design, published by the Associated Spring Corporation. I have had the best results, in the preferred embodiment of my invention, using helical clock or flat steel springs having a circular cross-section. Spring 4 abuts the top side of base disk 16 at the spring bottom end. Top disk 6 has about the same, or preferably slightly less diameter as base disk 16 and is attachably affixed to the top stem-end. Top disk 6 is preferably metallic as it is known that magnetic strength of a magnet is increased on one face if a metal mass is magnetically engaged near the opposite pole. In the preferred embodiment, top disk 6 is metallic and is provided with a central disk bore s therethrough. Also in the preferred embodiment, top disk 6 is provided with depression 7 concentric with the central hole in the direction toward the base disk when the top disk is installed on flexible stem 5. The preferred means of attaching top disk 6 to stem 5 is provided in a tip 13, preferably substantially cone-shaped, which is permanently affixed to and preferably molded integral with stem 5 and base disk 16. The diameter of disk bore 8 and the dimensions of the tip 13 are selected in light of the ability of tip to yield to allow insertion through the central hole from stem side of the top disk. Top disk 6 having disk bore s should preferably be locatable upon stem cone 13 and when a moderate force is applied to the nut face of top disk 6. In such assembly, stem tip 13 diameter yields, allowing the disk to pass over the base of stem tip 13. In an alternate preferred embodiment of FIG. 2, the top disk incorporates a slot 7, radially extending the central bore 8 to the edge. In this embodiment, the slot allows for the assembly of the top disk at the top stem-end by passing the stem along the slot to the central bore 8. The above preferred and alternate top disk assembly step is carried out with compression spring 4 in place around stem 5, the spring preferably being placed in compression, or "pre-stressed", as a result of assembly of the top disk, such that spring 4 firmly abuts the stem face of top disk 6, further firmly urging outward to force the top disk to positively abut the underside of stem tip 13 about the top rim of central bore 8. The outward bias of spring 4 in the normal assembled position should not however, be so great as to result in a yielding of the stem tip 13. With the top disk in place following the above preferred assembly method, permanent magnet 9 may be permanently affixed to the top side thereof. The magnet should preferably have a high retentivity, a high remanence, and a high coercive force. These properties are generally found in magnets made from hardened steel and its alloys, and also in ceramic material magnets. Magnet 9 is preferably a round ceramic-type magnet, and affixed to the top disk 6 with an epoxy or other well-known strong bonding composition. In doing so, stem tip 13 is preferably also bonded to the top disk 6. Magnet 9 may alternatively be ring shaped; however, I have found it preferable that the top side of the magnet be solid to avoid accumulation of dirt and grease and the like during repeated operation of the tool. The driving bore 2 of the socket may be hexagonal in shape, or alternatively may have any other multiply-ridqed edge to engage a nut, bolt or the like. Further, the nut-engaging shape of the socket driving bore may continue from the top edge for any length toward the shank end of the socket. As is typical with many deep-well type sockets presently commercially available, the driving bore extends partially down the socket well in the direction of the shank end, where the socket well transitions to a smooth faced bore for some length between the driving bore and the shank mating bore. My invention is useful with sockets of both types, although I have found it somewhat more advantageous when such a smooth transition bore is present between the driving bore and the shank mating bore. In the preferred embodiment of my invention, I have found it particularly advantageous to provide the base disk 16 with sidewall 3 integral therewith. The sidewall is preferably molded from plastic with the base disk and stem, and extends around the outer rim of the base disk in a plurality of sections. If such a sidewall is provided, I have further found it advantageous to form the sidewall extending upward from the base disk with a slight angle outward from the base disk, preferably at an angle of from between about 95 degrees to about 100 degrees relative to the face of the base disk, depending upon the height of the sidewall and the rigidity of the material from which it is formed. The purpose of such preferably outwardly extending sidewalls is to provide a holding force for retaining the base disk in the bottom of the socket well. In order to accomplish such a result, the diameter of the upper rim of the plurality of sidewalls 3 is sized to be normally slightly larger than the inside diameter of the bore section in which it is to be located. Referring now to FIG. 2, the socket insert is assembled and placed in normal position within the socket well. In the preferred embodiment the top of magnet 9 is normally positioned somewhat below the top edge of the driving bore, such that the driving bore may engage the fastening member, while still allowing for exposure of the fastening member above the socket edge to enable easy removal of the fastening member from the magnet. It is particularly desirable and suggested that when the nut-ejecting insert is to be used with power tools the top of magnet 9 is placed below the top edge of the socket well to avoid the possibility of the nut inadvertently being thrown from the driving tool and endangering the operator or by-standers. Still referring to FIG. 3, the preferred embodiment of the driving tool is depicted in the normal ready position to drive fastening member 11 onto threaded stem 12. It will be readily apparent to those familiar with sockets and driving tools that the same operation occurs, but in reverse, during disassembly or removal of the fastening member from the stem or the like. To drive the fastening member onto stem 12, shank 10 imparts a driving force to socket 1 through the shank bore 15. The shank 10 at the other end may be connected to a rachet, hand driver or power tool of the well known type. Shank bore 15 may be of various geometry, but is typically square and provided with well-known means for retaining the socket on the shank. Fastening member 11 is in this diagram a nut, and is preferably magnetically engaged and within the socket well at least a portion of the nut length such that the driving bore is effective to cause the threaded nut to rotate and positively engage the threaded portion on the mated threaded stem 12. Referring now to FIG. 4, the driving tool in the same cross-section view as shown in FIG. 3 is depicted in the driving position, which is the same position as would occur in the case of disassembly, of course rotating the driving tool and shank in the opposite direction. Among other key features, when force is applied through the shank in the direction of the fastening member, the magnet and top disk move into the socket well in the direction of the shank end, compressing the spring. As depicted in FIG. 4, flexible stem 5 deforms out of its normal and fully extended position substantially in the axis of the socket rotation to a non-linear shape, as the distance between the base disk and top disk is lessened. I have found the plastic material from which the base disk and stem preferably formed to be adequately flexible and capable of the intended deformation in the practice of my invention when the stem diameter is between about 1/32 and about 1/8 inches. The optimum diameter selected is a matter of choice and also dependant upon the size of the socket bore and rigidity of the plastic material selected. Further, I have found the operation of my invention to be best when the maximum compression of the spring is limited and thus the distance between the base and top disk is limited to about one-half, preferably one-third of the distance between the base and top disks in the normal position; however, my invention is not confined to such preferable conditions. When the driving operation is completed, the socket is retracted in the direction of the shank away from the fastening member, and the fastening member or corresponding stem is magnetically disengaged from the magnet, with the socket insert assembly remaining in place within the socket well. It will be apparent to one skilled in the art that various modifications to and variations of the socket insert and driving tool of my invention are possible without departing from the true scope and spirit of my invention. Such variations and modifications to the above specification and attached drawings referenced therein are intended to be within the scope of the appended Claims presented below.	A driving tool comprising a magnet and compression spring assembly insertable into a socket is disclosed. The insertable assembly comprises a flexible stem internal to the spring in the axis of rotation allowing the spring to compress and proving a straightening and travel limiting function. The nut or bolt is conveniently placed at the top edge of the socket for easy removal following disassembly, or positioning prior to a driving operation.	1
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in-part of the following U.S. patent applications: U.S. patent application Ser. No. 10/300,504, which is a division of U.S. patent application Ser. No. 09/833,902, now U.S. Pat. No. 6,512,814; U.S. patent application Ser. No. 10/313,280; and U.S. patent application Ser. No. 10/364,883. These related applications are assigned to the assignee of the present patent application, and their disclosures are incorporated herein by reference. FIELD OF THE INVENTION [0002] The present invention relates generally to analytical instruments, and specifically to instruments and methods for thin film analysis using X-rays. BACKGROUND OF THE INVENTION [0003] X-ray reflectometry (XRR) is a well-known technique for measuring the thickness, density and surface quality of thin film layers deposited on a substrate. Conventional X-ray reflectometers are sold by a number of companies, among them Technos (Osaka, Japan), Siemens (Munich, Germany) and Bede Scientific Instrument (Durham, UK). Such reflectometers typically operate by irradiating a sample with a beam of X-rays at grazing incidence, i.e., at a small angle relative to the surface of the sample, near the total external reflection angle of the sample material. Measurement of X-ray intensity reflected from the sample as a function of angle gives a pattern of interference fringes, which is analyzed to determine the properties of the film layers responsible for creating the fringe pattern. The X-ray intensity measurements are commonly made using a position-sensitive detector, such as a proportional counter or an array detector, typically a photodiode array or charge-coupled device (CCD). [0004] A method for analyzing the X-ray data to determine film thickness is described, for example, in U.S. Pat. No. 5,740,226, to Komiya et al., whose disclosure is incorporated herein by reference. After measuring X-ray reflectance as a function of angle, an average reflectance curve is fitted to the fringe spectrum. The average curve is based on a formula that expresses attenuation, background and surface roughness of the film. The fitted average reflectance curve is then used in extracting the oscillatory component of the fringe spectrum. This component is Fourier transformed to find the film thickness. [0005] U.S. Pat. No. 5,619,548, to Koppel, whose disclosure is incorporated herein by reference, describes an X-ray thickness gauge based on reflectometric measurement. A curved, reflective X-ray monochromator is used to focus X-rays onto the surface of a sample. A position-sensitive detector, such as a photodiode detector array, senses the X-rays reflected from the surface and produces an intensity signal as a function of reflection angle. The angle-dependent signal is analyzed to determine properties of the structure of a thin film layer on the sample, including thickness, density and surface roughness. [0006] U.S. Pat. No. 5,923,720, to Barton et al., whose disclosure is incorporated herein by reference, also describes an X-ray spectrometer based on a curved crystal monochromator. The monochromator has the shape of a tapered logarithmic spiral, which is described as achieving a finer focal spot on a sample surface than prior art monochromators. X-rays reflected or diffracted from the sample surface are received by a position-sensitive detector. [0007] Another common method of X-ray reflectometric measurement is described, for example, in an article by Naudon et al., entitled “New Apparatus for Grazing X-ray Reflectometry in the Angle-Resolved Dispersive Mode,” in Journal of Applied Crystallography 22 (1989), p. 460, which is incorporated herein by reference. A divergent beam of X-rays is directed toward the surface of a sample at grazing incidence, and a detector opposite the X-ray beam source collects reflected X-rays. A knife edge is placed close to the sample surface immediately above a measurement location in order to cut off the primary X-ray beam. A monochromator between the sample and the detector (rather than between the source and sample, as in U.S. Pat. No. 5,619,548) selects the wavelength of the reflected X-ray beam that is to reach the detector. [0008] XRR may also be used in situ, within a deposition furnace, to inspect thin film layers in production on a semiconductor wafer, as described, for example, by Hayashi et al., in U.S. Patent Application Publication U.S. 2001/0043668 A1, whose disclosure is incorporated herein by reference. The furnace is provided with X-ray incidence and extraction windows in its side walls. The substrate upon which the thin film has been deposited is irradiated through the incidence window, and the X-rays reflected from the substrate are sensed through the X-ray extraction window. SUMMARY OF THE INVENTION [0009] Embodiments of the present invention provide methods and systems for performing XRR measurements with enhanced accuracy. These methods and systems are advantageous in analyzing thin film layers, and particularly in characterizing low-density materials, such as low-k porous dielectrics, that are deposited on a higher-density underlying layer, such as a silicon wafer. [0010] In some embodiments of the present invention, the angular scale of an XRR fringe pattern generated by a thin film layer is calibrated based on the known reflectance properties of the underlying layer. The structure of the fringe pattern depends on the density, thickness and other properties of the thin film, but the pattern may also include a distinct shoulder at the critical angle for total external reflection from the underlying layer, particularly when the density of the thin film layer is lower than that of the underlying layer. This critical angle, in turn, is determined by the composition and density of the underlying layer. If the parameters of the underlying layer are known (as they are, for example, when the underlying layer is a silicon wafer substrate), the angular scale of the XRR fringe pattern can then be calibrated precisely based on the location of the shoulder. [0011] In further embodiments of the present invention, an array of X-ray detector elements is used to measure XRR fringe patterns with sub-pixel resolution. For this purpose, the sample is irradiated by a converging X-ray beam. The array is positioned and oriented so that the elements of the array resolve the radiation reflected from the sample along an axis perpendicular to the plane of the sample. The array is then translated along the axis by an increment that is less than the pitch of the array, and the measurement is repeated. Preferably, the increment is equal an integer fraction of the pitch of the array (pitch/n, wherein n is an integer), and the measurement is repeated at n different positions of the array along the axis. The XRR measurements made at the different positions are combined, typically by interleaving the measurements taken at the different increments, in order to obtain a fringe spectrum with enhanced resolution. [0012] Although the embodiments of the present invention described herein are directly mainly toward enhancing X-ray measurements on thin films, and particularly on films formed on semiconductor wafers, the principles of the present invention can similarly be used in other applications of X-ray reflectometry and scattering, as well as in other types of radiation-based analysis. [0013] There is therefore provided, in accordance with an embodiment of the present invention, a method for inspection of a sample that includes a first layer having a known reflectance property and a second layer formed over the first layer, the method including: [0014] directing radiation toward a surface of the sample; [0015] sensing the radiation reflected from the surface so as to generate a reflectance signal as a function of elevation angle relative to the surface; [0016] identifying a feature in the reflectance signal due to reflection of the radiation from the first layer; [0017] calibrating the reflectance signal responsively to the identified feature and to the known reflectance property of the first layer; and [0018] analyzing the calibrated reflectance signal to determine a characteristic of the second layer. [0019] Typically, the radiation includes X-rays, and sensing the radiation includes receiving the radiation at an array of detector elements having an array axis perpendicular to the surface. [0020] In disclosed embodiments, identifying the feature includes finding a location of a shoulder in the reflectance signal corresponding to a critical angle for total external reflection from the first layer. Typically, calibrating the reflectance signal includes comparing the location of the shoulder to a known value of the critical angle, which is determined by a known density of the first layer. Calibrating the reflectance signal typically includes finding a zero angle in an angular scale of the reflectance signal based on the location of the shoulder and the known value of the critical angle. [0021] In some embodiments, when the critical angle for total external reflection from the first layer is a first critical angle, analyzing the calibrated reflectance signal includes determining a calibrated value of a second critical angle for total external reflection from the second layer. Typically, the first and second layers have respective first and second densities, and analyzing the calibrated reflectance signal includes estimating the second density based on the calibrated value of the second critical angle, wherein the second density may be substantially less than the first density. In one embodiment, the first layer includes silicon, and the second layer includes a porous dielectric material. [0022] There is also provided, in accordance with an embodiment of the present invention, apparatus for inspection of a sample that includes a first layer having a known reflectance property and a second layer formed over the first layer, the apparatus including: [0023] a radiation source, which is adapted to direct X-rays toward a surface of the sample; [0024] a detector assembly, which is arranged to sense the radiation reflected from the surface so as to generate a reflectance signal as a function of elevation angle relative to the surface; and [0025] a signal processor, which is coupled to receive and process the reflectance signal by identifying a feature in the reflectance signal due to reflection of the radiation from the first layer and calibrating the reflectance signal responsively to the identified feature and to the known reflectance property of the first layer, and to analyze the calibrated reflectance signal to determine a characteristic of the second layer. [0026] There is additionally provided, in accordance with an embodiment of the present invention, apparatus for inspection of a sample, including: [0027] a radiation source, which is adapted to direct X-rays toward a surface of the sample; [0028] a detector assembly, which includes: [0029] an array of detector elements, which are arranged along an array axis substantially perpendicular to the surface and are mutually separated by a predetermined pitch, and which are operative to receive the X-rays reflected from the surface and to generate signals responsively to the received radiation; and [0030] a motion element, which is coupled to shift the array of detector elements in a direction parallel to the array axis between at least first and second positions, which positions are separated one from another by an increment that is not an integer multiple of the pitch; and [0031] a signal processor, which is coupled to combine the signals generated by the detector assembly in at least the first and second positions so as to determine an X-ray reflectance of the surface as a function of elevation angle relative to the surface. [0032] Typically, the signal processor is adapted to interleave the signals generated by the detector assembly in at least the first and second positions in order to determine the X-ray reflectance of the surface. [0033] In disclosed embodiments, the increment is less than or equal to one half of the pitch. [0034] Typically, the array includes a linear array, and the detector elements have a transverse dimension, perpendicular to the array axis, that is substantially greater than a pitch of the array. Alternatively, the array includes a two-dimensional matrix of the detector elements, and the detector assembly is adapted to bin the detector elements in respective rows of the array along a direction perpendicular to the array axis. [0035] There is further provided, in accordance with an embodiment of the present invention, a method for inspection of a sample, including: [0036] directing X-rays toward a surface of the sample; [0037] configuring an array of detector elements, which are mutually separated by a predetermined pitch, to receive the X-rays reflected from the surface while resolving the received radiation along an array axis substantially perpendicular to the surface; [0038] shifting the array of detector elements in a direction parallel to the array axis between at least first and second positions, which positions are separated one from another by an increment that is not an integer multiple of the pitch; [0039] receiving at least first and second signals generated by the detector elements responsively to the X-rays received thereby in at least the first and second positions, respectively; and [0040] combining at least the first and second signals so as to determine an X-ray reflectance of the surface as a function of elevation angle relative to the surface. [0041] There is moreover provided, in accordance with an embodiment of the present invention, a cluster tool for producing microelectronic devices, including: [0042] a deposition station, which is adapted to deposit a thin-film layer over an underlying layer on a surface of a semiconductor wafer, the underlying layer having a known reflectance property; and [0043] an inspection station, including: [0044] a radiation source, which is adapted to direct X-rays toward the surface of the wafer; [0045] a detector assembly, which is arranged to sense the radiation reflected from the surface so as to generate a reflectance signal as a function of elevation angle relative to the surface; and [0046] a signal processor, which is coupled to receive and process the reflectance signal by identifying a feature in the reflectance signal due to reflection of the radiation from the underlying layer and calibrating the reflectance signal responsively to the identified feature and to the known reflectance property of the underlying layer, and to analyze the calibrated reflectance signal to determine a characteristic of the thin-film layer deposited by the deposition station. [0047] There is furthermore provided, in accordance with an embodiment of the present invention, apparatus for producing microelectronic devices, including: [0048] a production chamber, which is adapted to receive a semiconductor wafer; [0049] a deposition device, which is adapted to deposit a thin-film layer over an underlying layer on a surface of the semiconductor wafer within the chamber, the underlying layer having a known reflectance property; [0050] a radiation source, which is adapted to direct X-rays toward the surface of the semiconductor wafer in the chamber; [0051] a detector assembly, which is arranged to sense the radiation reflected from the surface so as to generate a reflectance signal as a function of elevation angle relative to the surface; and [0052] a signal processor, which is coupled to receive and process the reflectance signal by identifying a feature in the reflectance signal due to reflection of the radiation from the underlying layer and calibrating the reflectance signal responsively to the identified feature and to the known reflectance property of the underlying layer, and to analyze the calibrated reflectance signal to determine a characteristic of the thin-film layer deposited by the deposition device. [0053] There is also provided, in accordance with an embodiment of the present invention, a cluster tool for producing microelectronic devices, including: [0054] a deposition station, which is adapted to deposit a thin-film layer on a surface of a semiconductor wafer; and [0055] an inspection station, including: [0056] a radiation source, which is adapted to direct X-rays toward the surface of the wafer; [0057] a detector assembly, which includes: [0058] an array of detector elements, which are arranged along an array axis substantially perpendicular to the surface and are mutually separated by a predetermined pitch, and which are operative to receive the X-rays reflected from the surface and to generate signals responsively to the received radiation; and [0059] a motion element, which is coupled to shift the array of detector elements in a direction parallel to the array axis between at least first and second positions, which positions are separated one from another by an increment that is not an integer multiple of the pitch; and [0060] a signal processor, which is coupled to combine the signals generated by the detector assembly in at least the first and second positions so as to determine an X-ray reflectance of the thin-film layer as a function of elevation angle relative to the surface. [0061] There is additionally provided, in accordance with an embodiment of the present invention, apparatus for producing microelectronic devices, including: [0062] a production chamber, which is adapted to receive a semiconductor wafer; [0063] a deposition device, which is adapted to deposit a thin-film layer on a surface of the semiconductor wafer within the chamber; [0064] a radiation source, which is adapted to direct X-rays toward the surface of the semiconductor wafer in the chamber; [0065] a detector assembly, which includes: [0066] an array of detector elements, which are arranged along an array axis substantially perpendicular to the surface and are mutually separated by a predetermined pitch, and which are operative to receive the X-rays reflected from the surface and to generate signals responsively to the received radiation; and [0067] a motion element, which is coupled to shift the array of detector elements in a direction parallel to the array axis between at least first and second positions, which positions are separated one from another by an increment that is not an integer multiple of the pitch; and [0068] a signal processor, which is coupled to combine the signals generated by the detector assembly in at least the first and second positions so as to determine an X-ray reflectance of thin-film layer as a function of elevation angle relative to the surface. [0069] There is further provided, in accordance with an embodiment of the present invention, a method for inspection of a sample, including: [0070] directing radiation from a radiation source in a first predetermined position toward a radiation sensor in the second predetermined position; [0071] sensing the radiation that is directly incident on the radiation sensor from the radiation source so as to generate a first direct signal as a function of elevation angle, while a shutter is positioned so as to cut off the radiation at a predetermined cutoff angle; [0072] sensing the radiation that is directly incident on the radiation sensor from the radiation source so as to generate a second direct signal as a function of the elevation angle, while the shutter is positioned so as not to cut off the radiation at the predetermined cutoff angle; [0073] introducing a sample between the radiation source in the first predetermined position and the radiation sensor in the second predetermined position, so that the radiation is incident on a surface of the sample; [0074] sensing the radiation reflected from the surface of the sample onto the radiation sensor so as to generate a first reflectance signal as a function of the elevation angle, while the shutter is positioned so as to cut off the radiation at the predetermined cutoff angle; [0075] sensing the radiation reflected from the surface of the sample onto the radiation sensor so as to generate a second reflectance signal as a function of the elevation angle, while the shutter is positioned so as not to cut off the radiation at the predetermined cutoff angle; and [0076] comparing a first ratio between the first direct signal and the second direct signal with a second ratio between the first reflectance signal and the second reflectance signal in order to find the elevation angle of a tangent to the surface. [0077] Typically, the method includes analyzing the first and second reflectance signals so as to determine a property of a thin film layer at the surface of the sample. [0078] In a disclosed embodiment, comparing the first ratio with the second ratio includes finding a first elevation angle at which the first ratio has a given value and a second elevation angle at which the second ratio has the given value, and determining the elevation angle of the tangent to the surface to be an average of the first and second elevation angles. Additionally or alternatively, the method includes taking a difference between the first and second elevation angles so as to determine a minimum elevation angle below which the shutter cuts off the radiation. [0079] There is moreover provided, in accordance with an embodiment of the present invention, apparatus for inspection of a sample, including: [0080] a radiation source in a first predetermined position, which is adapted to generate radiation; [0081] a shutter, which is positionable so as to cut off the radiation at a predetermined cutoff angle; [0082] a motion stage, which is configured to position a sample so that the radiation generated by the radiation source is incident on a surface of the sample; [0083] a radiation sensor in a second predetermined position, which is adapted to sense the radiation so as to generate signals responsive to the radiation incident on the radiation sensor as a function of elevation angle, the signals including: [0084] a first direct signal responsive to the radiation that is directly incident on the radiation sensor from the radiation source while the shutter is positioned so as to cut off the radiation at the predetermined cutoff angle; [0085] a second direct signal responsive to the radiation that is directly incident on the radiation sensor from the radiation source while the shutter is positioned so as not to cut off the radiation at the predetermined cutoff angle; [0086] a first reflectance signal responsive to the radiation reflected from the surface of the sample onto the radiation sensor while the shutter is positioned so as to cut off the radiation at the predetermined cutoff angle; and [0087] a second reflectance signal responsive to the radiation reflected from the surface of the sample onto the radiation sensor while the shutter is positioned so as not to cut off the radiation at the predetermined cutoff angle; and [0088] a signal processor, which is coupled to compare a first ratio between the first direct signal and the second direct signal with a second ratio between the first reflectance signal and the second reflectance signal in order to find the elevation angle of a tangent to the surface. [0089] It should be understood that the terms “first” and “second” are used above and in the claims arbitrarily. Thus, for example, these terms do not necessarily reflect the actual order in which the signals described above are received. [0090] The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS [0091] [0091]FIG. 1 is a schematic side view of a system for X-ray reflectometry (XRR) measurements, in accordance with an embodiment of the present invention; [0092] [0092]FIG. 2 is a schematic, frontal view of a detector array, configured for XRR, in accordance with an embodiment of the present invention; [0093] [0093]FIG. 3 is a schematic plot of XRR measurements, in accordance with an embodiment of the present invention; [0094] [0094]FIG. 4 is a schematic plot of XRR measurements, illustrating a method for acquiring XRR spectra with sub-pixel resolution, in accordance with an embodiment of the present invention; [0095] [0095]FIG. 5A is a schematic side view of the system of FIG. 1, showing the angles subtended by an X-ray beam in different configurations of a shutter and sample in the system, in accordance with an embodiment of the present invention; [0096] [0096]FIG. 5B is a schematic plot of X-ray measurement results used in determining a zero angle for incidence of X-rays on the sample in the system shown in FIG. 5A, in accordance with an embodiment of the present invention; [0097] [0097]FIG. 6 is a schematic top view of a cluster tool for semiconductor device fabrication, including an inspection station in accordance with an embodiment of the present invention; and [0098] [0098]FIG. 7 is a schematic side view of a semiconductor processing chamber with X-ray inspection capability, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS [0099] Reference is now made to FIG. 1, which is a schematic side view of a system 20 for X-ray reflectometry (XRR), in accordance with an embodiment of the present invention. System 20 is similar to the XRR system described in the above-mentioned U.S. Pat. No. 6,512,814, with the addition of features and capabilities described herein. [0100] A sample 22 , such as a semiconductor wafer, to be evaluated by system 20 is mounted on a motion stage 24 , allowing accurate adjustment of its position and orientation. An X-ray source 26 , typically an X-ray tube with suitable monochromatizing optics (not shown), irradiates a small area 28 on sample 22 . For example, the XTF5011 X-ray tube, produced by Oxford Instruments (Scotts Valley, Calif.), may be used for this purpose. The optics focus the radiation from the X-ray tube onto area 28 in a converging beam 27 . A number of different optical configurations that may be used in source 26 are described in U.S. Pat. No. 6,381,303, whose disclosure is incorporated herein by reference. For example, the optics may comprise a curved crystal monochromator, such as the Doubly-Bent Focusing Crystal Optic, produced by XOS Inc., of Albany, N.Y. Other suitable optics are described in the above-mentioned U.S. Pat. Nos. 5,619,548 and 5,923,720. Further possible optical configurations will be apparent to those skilled in the art. A typical X-ray energy for reflectometric and scattering measurements in system 20 is about 8.05 keV (CuKa1). Alternatively, other energies may be used, such as 5.4 keV (CrKa1). [0101] A dynamic knife edge 36 and shutter 38 are used to limit the angular extent of incident beam 27 of the X-rays in the vertical direction (i.e., perpendicular to the plane of sample 22 ), while a slit 39 may be used to limit the beam horizontally. The knife edge, shutter and slit together serve as a shutter assembly, for adjusting the transverse dimensions of beam 27 . The configuration of the shutter assembly in FIG. 1 is shown by way of example, and alternative arrangements of X-ray optics for controlling the transverse dimensions of beam 27 in the manner described hereinbelow will be apparent to those skilled in the art and are considered to be within the scope of the present invention. [0102] The use of knife edge 36 and shutter 38 in XRR measurements is described in detail in the above-mentioned U.S. Pat. No. 6,512,814. Briefly, for optimal detection of low-angle reflections, near 0°, shutter 38 is withdrawn outside the extent of incident beam 27 , while knife edge 36 is positioned over area 28 and is lowered to reduce the effective vertical cross-section of the beam. As a result, the lateral dimension of the X-ray spot incident on area 28 is reduced. On the other hand, for effective detection of weaker, high-angle reflection, knife edge 36 is withdrawn from beam 27 , while shutter 38 is positioned to cut off the low-angle portion of the beam. (Alternatively, the shutter may be positioned to cut off the low-angle portion of reflected beam 29 .) In this manner, only the high-angle reflections from sample 22 reach the detector array, and not the strong low-angle reflections, thus enhancing the signal/background ratio of the high-angle measurement. During XRR measurements, slit 39 is typically wide open, in order to admit the full cone of converging rays and thus increase the signal/noise ratio of the reflectivity measurement. [0103] A reflected beam 29 of X-rays from sample 22 is collected by a detector assembly 30 . Typically, for XRR, assembly 30 collects reflected X-rays over a range of reflection angles in the vertical (elevation—φ) direction between about 0° and 3°, both below and above the critical angle of the sample for total external reflection. (For clarity of illustration, the angles shown in the figures are exaggerated, as is the elevation of source 26 and detector assembly 30 above the plane of sample 22 in FIG. 1.) [0104] Assembly 30 comprises a detector array 32 , such as a CCD array, as described hereinbelow. Although for simplicity of illustration, only a single row of detectors elements is shown in the figures, with a relatively small number of detector elements, array 32 generally includes a greater number of elements, arranged as either a linear array or a matrix (two-dimensional) array. Assembly 30 may comprise a translation element 33 , of any suitable type known in the art, for shifting and aligning array 32 relative to sample 22 . Assembly 30 further comprises a window 34 made of a suitable X-ray transparent material, such as beryllium, spaced in front of the detector array, between the array and the sample. Further details of the operation of array 32 are described below with reference to FIG. 2. [0105] A signal processor 40 analyzes the output of assembly 30 , so as to determine a distribution 42 of the flux of X-ray photons reflected from sample 22 as a function of angle at a given energy or over a range of energies. Typically, sample 22 has one or more thin surface layers, such as thin films, at area 28 , so that distribution 42 as a function of elevation angle exhibits an oscillatory structure due to interference effects among reflected X-ray waves from the interfaces between the layers. Processor 40 analyzes characteristics of the angular distribution in order to determine characteristics of one or more of the surface layers of the sample, such as the thickness, density and surface quality of the layer, using methods of analysis described hereinbelow. [0106] [0106]FIG. 2 is a schematic frontal view of array 32 , in accordance with an embodiment of the present invention. Array 32 is shown in this figure as comprising a single row of detector elements 46 , with an array axis that is aligned along an axis perpendicular to the plane of sample 22 . Elements 46 have a high aspect ratio, i.e., their width, in the direction transverse to the array axis, is substantially greater than their pitch along the axes. The high aspect ratio is useful in enhancing the signal/noise ratio of system 20 , since array 32 is thus able to collect X-ray photons over a relatively wide area for each angular increment along the array axis. The dimensions of elements 46 are shown in the figures solely by way of example, however, and the principles of the present invention may be applied using elements of smaller or larger aspect ratio, depending on application needs and availability of suitable detector devices. [0107] As noted above, array 32 may comprise either a linear CCD array or a matrix array, such as the model S7032-1008 array produced by Hamamatsu, of Hamamatsu City, Japan. This latter array comprises 1044×256 pixels, with an overall size of 25.4×6 mm. It is capable of being operated in a line-binning mode, using special hardware supplied for this purpose by Hamamatsu, so that multiple detector elements in each row of the array function effectively as a single element with high aspect ratio. In this case, although array 32 physically comprises a two-dimensional matrix of detector elements, functionally the array takes the form of a single line of detector elements, as shown in FIG. 2. [0108] Alternatively, array 32 may comprise an array of PIN diodes with suitable readout circuits, possibly including integrated processing electronics, as described in U.S. Pat. No. 6,389,102, whose disclosure is incorporated herein by reference. This patent also describes alternative features of the array, including various geometrical configurations of the array (both one- and two-dimensional) and masking that may be applied to enhance the array's detection properties. These features are applicable to assembly 30 of the present patent application, as well. In any event, it will be understood that these detector types are described here by way of example, and detectors of any suitable type, dimension and number can be used. [0109] In one aspect of the present invention, illustrated in FIG. 2, array 32 is shifted by small increments in the Z-direction, using translation element 33 (FIG. 1), for example. Two vertical positions 45 and 47 of array 32 are shown, separated by an increment in the Z-direction of one-half the pitch of the array, i.e., one-half the center-to-center separation of detector elements 46 . (Although positions 45 and 47 are shown in FIG. 2 as being horizontally offset, as well, the horizontal offset is used solely for the purpose of clarity of illustration in this figure and is not necessary or desirable in XRR measurements.) In each position 45 and 47 , source 26 is actuated, and assembly 30 captures the X-rays reflected from sample 22 as a function of the elevation angle. Assembly 30 may be operated in this manner to capture X-rays at more than two different vertical positions, typically with a smaller Z-direction increment between the positions. For example, three different positions separated by ⅓ the array pitch may be used. [0110] The signals generated by assembly 30 in each different vertical position are input to processor 40 , which combines the readings made at the different positions into a single spectrum. Essentially, the processor creates a “virtual array,” with finer resolution than the actual, physical array 32 . The signals in the virtual array can be derived, for example, simply by interleaving the readings made in the different array positions. Thus, for each “virtual pixel” in the virtual array, processor 40 selects the measurement value of a real pixel at the corresponding position in one of the actual measurements, alternating from one virtual pixel to the next among the readings made in the different measurement positions. In other words, assume the following read pixel readings were made in three successive positions of the array: [0111] Position 1: R11, R21, R31, R41, . . . [0112] Position 2: R12, R22, R32, R42, . . . [0113] Position 3: R13, R23, R33, R43, . . . [0114] The resultant virtual array will then contain the following values, at virtual pixels separated by ⅓ the actual array pitch: R11, R12, R13, R21, R22, R23, R31, R32, R33, R41, . . . [0115] Alternatively, other methods, such as signal differentiation or summing of the readings in the different array positions, may be used to extract XRR information from the individual, actual measurements before combining them, or to select the actual measurement result to be used in each pixel of the virtual array. [0116] The resolution-enhancement techniques described hereinabove are useful particularly when the XRR spectrum has a fine structure with high spatial frequency, so that the fringe separation is comparable to or smaller than the array pitch. Alternatively, when the XRR spectrum is sufficiently strong and the fringes are well separated, it may be sufficient to measure the XRR signal at a single vertical position, such as position 45 , in order to extract an acceptable spectrum. [0117] [0117]FIGS. 3 and 4 are schematic plots of XRR measurements made using system 20 , in accordance with an embodiment of the present invention. Plots of this sort may be generated using signals received at a single vertical position of array 32 or by combining signals from two or more different vertical positions, as described above. The plot in FIG. 3 shows the intensity of reflected X-rays received by array 32 in a single vertical position, as a function of the elevation angle φ, using Cu Kα (8.05 keV) radiation from source 26 . FIG. 4 , described below, shows the result of combining signals captured at multiple different vertical positions of array 32 . [0118] An upper curve 50 shows the reflection measured from a bare silicon wafer, while a lower curve 52 shows the reflection from a wafer on which a low-k porous dielectric film has been formed. Both curves have a shoulder at an angle marked in the figure as φ 2 , slightly greater than 0.2°. This angle corresponds to the critical angle for total external reflection from silicon. More precisely, for a standard silicon wafer with density 2.33 g/cm 3 , the critical angle at 8.05 keV is 0.227°. Therefore, once the location of the shoulder at φ 2 is found, the zero point in the angular (horizontal) scale in the spectrum of FIG. 3 can be determined precisely, simply by going back 0.227° to the left of φ 2 . The scaling factor of the angular scale, in degrees per detector element 46 , is given by 180 ° π  arctan  ( array   pitch focal   dist ) ≅ 180  ° π  ( array   pitch focal   dist ) , [0119] wherein the focal distance is the distance from focal area 28 to array 32 . Alternatively or additionally, the angular scale can be calibrated absolutely, based on the shoulder at φ 2 but without reference to the array pitch and focal distance, using the method described in the above-mentioned U.S. patent application Ser. No. 10/313,280. [0120] Above the critical angle, curve 52 shows an oscillatory structure, due mainly to reflections from the upper and lower surfaces of the low-k film. The period and amplitude of this oscillation may be analyzed to determine the thickness and surface quality of the low-k film and possibly other thin film layers below it on the wafer. A Fast Fourier Transform (FFT), for example, may be used to extract the relevant characteristics of the oscillation. Alternatively, a parametric curve fitting method may be used to give a more accurate determination of the film parameters. Methods for analyzing XRR signals such as curve 52 are described in greater detail in the above-mentioned U.S. Pat. No. 6,512,814. [0121] The critical angle, and hence the location of the shoulder in the reflectance curve, is determined mainly by the density of the material from which the X-rays reflect. Since the porous, low-k dielectric layer that is deposited on the wafer has a substantially lower density than the silicon substrate, the critical angle of the porous layer is substantially smaller than that of the underlying silicon. Therefore, another shoulder is seen in curve 52 , at a smaller angle marked in the figure as φ 1 , corresponding to the critical angle of the porous layer. The exact value of φ 1 can be determined from the calibration of the angular scale described above, using the known value of φ 2 . Processor 40 is then able to determine the overall density of the porous material with high precision, based on the calibrated value of φ 1 . Since the intrinsic density of the dielectric material (in the absence of pores) is typically known, the total volume of pores, per unit volume of the porous layer, may be deduced as the difference between the known, intrinsic density of the dielectric material and the estimated overall density of the porous layer, based on the measured value of φ 1 . [0122] [0122]FIG. 4 shows the intensity of reflected X-rays received by array 32 as a function of the elevation angle φ, showing the result of combining multiple measurements made at different vertical positions of the array. The angular scale in this figure is expanded relative to that of FIG. 3. A raw curve 54 shows a typical measurement made at a single vertical position of array 32 . A combined curve 56 shows the result obtained by combining five measurements taken at different vertical positions of the array, which are offset one from the other in Z-direction increments of ⅕ of the array pitch. The pitch of the array is such that the angular separation between successive detector elements 46 is about 0.004°. [0123] The period of the oscillatory pattern of the reflected radiation, as seen in curve 56 , varies between about 0.007° and about 0.010°, which is near the Nyquist limit of array 32 . Therefore, curve 54 fails to capture a portion of the true oscillatory structure, which appears in curve 56 , and reproduces other portions of the structure with poor fidelity. On the other hand, when multiple measurements are combined, the portions of the oscillatory structure that are lost in curve 54 are captured successfully in other measurements. As a result, the effective resolution of array 32 is enhanced, as illustrated by curve 56 . The enhancement gained in this manner may provide resolution that is effectively finer than the resolution of the X-ray optics that are used to cast the oscillatory pattern on array 32 . As noted above, a theoretical model is fitted to curve 56 in order to determine parameters such as the thickness and surface quality of the surface layer on sample 22 . Since the XRR signal is by nature complex and exhibits non-linear frequency variation as a function of angle, the added data points that are gained by shifting the array in the manner described above are useful in improving the fit and hence extracting more accurate values of the surface layer parameters. [0124] Reference is now made to FIGS. 5A and 5B, which schematically illustrate a method for determining the zero angle of sample 22 , in accordance with an embodiment of the present invention. FIG. 5A is a schematic side view of system 20 , showing the angular spread of the X-ray beam generated by source 26 and incident on array 32 under different system conditions. The angular characteristics of the beam detected by array 32 under these different conditions are used in determining the zero angle of sample 22 . The term “zero angle” in this context is used to refer to the elevation angle of a tangent to the surface of sample 22 at the point of incidence of the X-ray beam on the sample. This zero angle is equivalent to the zero point noted above in the spectra shown in FIG. 3. Unlike the method described above for finding the zero point in these spectra, however, the method illustrated by FIGS. 5A and 5B does not rely on any particular sort of layer structure on sample 22 . The zero angle is found in the present context by identifying the detector element of array 32 that is aligned with the tangent to sample 22 (or in a virtual array created by the resolution enhancement technique described above, by finding the virtual pixel that is aligned with this tangent). [0125] [0125]FIG. 5A shows four different beam configurations: [0126] A narrow reflected beam 55 , which is incident on array 32 when sample 22 is in place and shutter 38 is positioned to cut off the low-angle portion of the beam, as shown in the figure. [0127] A broad reflected beam 57 , extending roughly down to the zero angle of sample 22 , when shutter 38 is withdrawn from the beam. [0128] A narrow direct beam 58 , which is incident on array 32 when sample 22 is removed from the X-ray beam path (so that there is no reflected beam), while shutter 38 is once again positioned to cut off the low-angle portion of the beam. [0129] A broad direct beam 59 , extending up to the zero angle of beam 57 , and typically even beyond this zero angle, when both the shutter and the sample are removed from the X-ray beam. [0130] Note that near the zero angle, the signal captured by array 32 due to beam 57 does not have a sharp cutoff, but rather increases gradually and not entirely smoothly. (For simplicity, this gradual increase is not shown in FIG. 3.) Therefore, it is difficult to determine the zero angle based on this signal alone. [0131] [0131]FIG. 5B is a schematic plot of the results of measurements made by array 32 under irradiation by beams 55 , 57 , 58 and 59 . The results are computed for each pixel on the horizontal (angular) axis as the ratio of the intensity value of the pixel due to one of the narrow beams to the value due to the corresponding one of the broad beams, i.e., RATIO=I NARROW /I BROAD . A left branch 61 of the plot, for elevation angles below the zero angle, is generated by computing the ratio of each pixel value measured when beam 58 is incident on array 32 to the value measured when beam 59 is incident. A right branch 63 , for elevation angles above the zero angle, is given by the ratio of each pixel value measured when beam 55 is incident on the array to the value measured when beam 57 is incident. [0132] As shown in FIG. 5B, the ratios for both positive and negative angles are typically zero in the vicinity of the zero angle, since shutter 38 cuts off beams 55 and 58 in this angular range. The ratios increase above zero at a cut-on angle, corresponding roughly to the angle at which shutter 38 intercepts the X-ray beam, growing gradually to a value of about one an angles away from the shutter edge. Branches 61 and 63 tend to be smooth curves, since local variations in the intensity values due to the narrow beam are typically canceled out by corresponding variations in the intensity values due to the broad beam. Therefore, the zero angle can be found accurately by taking the average angle between fifty-percent points 65 (at which the intensity ratio is 0.5). Alternatively, a curve fitting procedure may be applied to branches 61 and 63 , and the fit parameters may be used to find the zero angle. The angular position of shutter 38 is given by half the angular distance between points 65 . As a further alternative, curve 63 may be mirrored about a point on the horizontal axis so that it overlaps with curve 61 . The mirroring point that gives the best overlap between the two curves is identified as the zero angle. [0133] The method exemplified by FIGS. 5A and 5B can be used to find the zero angle at substantially any point on the surface of sample 22 , independently of the nature of the sample and of the presence or absence of certain types of surface layers on the sample. This method for finding the zero angle is particularly useful, for example, in X-ray reflectometry of semiconductor wafers, which tend to warp, so that the zero angle varies over the surface of the wafer. The method remains valid even if the incident X-ray beam is not uniform, and regardless of any angular variation in the reflected beam (as long as the reflectivity varies continuously as a function of angle). This method may be combined with the resolution enhancement method described above with reference to FIGS. 2 - 4 (in which signals are acquired at different positions of array 32 ) in order to determine the zero angle with even greater accuracy. [0134] Another advantage of the present method is that it can be carried out in concert with the actual XRR measurements, substantially without interrupting the measurement procedure. The measurements of direct beams 58 and 59 can be made whenever sample 22 is absent from system 20 , typically in between measurements of different samples. The measurements of reflected beams 55 and 57 can be made in parallel to the XRR measurements. For example, when the surface layer density of the sample is greater than about 1.5 g/cm 3 , the angular range between about 0.15° and 4° is used for XRR analysis, while the range between 0° and 0.15° can be used for zero angle calibration. [0135] To acquire the data used to create branch 63 , for example, shutter 38 is advanced to cut off the low-angle portion of the X-ray beam, below about 0.1°, and a reflection signal is acquired from array 32 over an exposure time of about 1-2 sec. The shutter is then retracted, and a further reflection signal is acquired from the array. The signals may be normalized in proportion to the ratio of exposure duration in the two shutter positions. The ratio of the normalized curves is calculated to find branch 63 . A similar procedure is used to create branch 61 . [0136] [0136]FIG. 6 is a schematic top view of a cluster tool 70 for use in semiconductor device fabrication, in accordance with an embodiment of the present invention. The cluster tool comprises multiple stations, including a deposition station 72 , for depositing thin films on a semiconductor wafer 77 , an inspection station 74 , and other stations 76 , as are known in the art, such as a cleaning station. Inspection station 74 is constructed and operates in a manner similar to system 20 , as described hereinabove. A robot 78 transfers wafer 77 among stations 72 , 74 , 76 , . . . , under the control of a system controller 80 . Operation of tool 70 may be controlled and monitored by an operator using a workstation 82 , coupled to controller 80 . [0137] Inspection station 74 is used to perform X-ray inspection of wafers by XRR before and after selected steps in production processes carried out by deposition station 72 and other stations in tool 70 . In an exemplary embodiment, deposition station 72 is used to create porous thin films, such as porous low-k dielectric layers, on wafer 77 , and inspection station 74 performs XRR evaluation, as described above. This arrangement allows early detection of process deviations and convenient adjustment and evaluation of process parameters on production wafers, using controller 80 and possibly workstation 82 . The techniques described above for finding zero angles and enhancing detection resolution may also be used in station 74 . [0138] [0138]FIG. 7 is a schematic side view of a system 90 for semiconductor wafer fabrication and in situ inspection, in accordance with another embodiment of the present invention. System 90 comprises a vacuum chamber 92 , containing deposition apparatus 94 , for creating thin films on wafer 77 , as is known in the art. The wafer is mounted on motion stage 24 within chamber 92 . The chamber typically comprises X-ray windows 96 , which may be of the type described in the above-mentioned Patent Application Publication U.S. 2001/0043668 A1. X-ray source 26 irradiates area 28 on wafer 77 via one of windows 96 , in the manner described above. The shutter, knife edge and slit shown in FIG. 1 are omitted from FIG. 7 for the sake of simplicity, but typically, elements of this sort are integrated into source 26 or within chamber 92 . [0139] X-rays reflected from area 28 are received by array 32 in detector assembly 30 via another one of windows 96 . Processor 40 receives signals from detector assembly 30 , and processes the signals in order to assess characteristics of thin-film layers in production within chamber 92 . The results of this assessment may be used in controlling deposition apparatus 94 so that the films produced by system 90 have desired characteristics, such as thickness, density and porosity. The techniques described above for finding zero angles and enhancing detection resolution may also be used in chamber 92 . [0140] Although the embodiments described above deal mainly with determining porosity characteristics of low-k dielectric layers on semiconductor wafers, the principles of the present invention can similarly be used in other X-ray reflectometry applications, as well as in other types of radiation-based analysis, using not only X-rays, but also other ionizing radiation bands. It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.	A method for inspection of a sample that includes a first layer having a known reflectance property and a second layer formed over the first layer. The method includes directing radiation toward a surface of the sample and sensing the radiation reflected from the surface so as to generate a reflectance signal as a function of elevation angle relative to the surface. A feature due to reflection of the radiation from the first layer is identified in the reflectance signal. The reflectance signal is calibrated responsively to the identified feature and to the known reflectance property of the first layer. The calibrated reflectance signal is analyzed to determine a characteristic of the second layer. Other enhanced inspection methods are disclosed, as well.	6
RELATED APPLICATION [0001] This application is a continuation of U.S. application Ser. No. 09/393,910, filed Sep. 10, 1999, which is incorporated herein by reference. BACKGROUND [0002] 1. Field of the Invention [0003] The present invention relates to enhanced control of a wafer processing facility. More specifically, the present invention relates to a system, method and medium for the accurate and highly responsive implementation of one or more instructions/functions relating to the production of wafers in a wafer processing facility, and particularly for controlling one or more wafer processing chambers within a wafer processing facility. The present invention accomplishes this by utilizing two or more processors, which may reside in separate computer processor systems, wherein each processor and/or computer processor system is assigned to control, and sample information relating to, one or more designated functions (e.g., temperature, pressure, etc.). [0004] 2. Related Art [0005] With each passing year, engineers continue to attempt to squeeze more and more circuits into a smaller and smaller space on integrated circuit chips. As a result, the various films deposited or grown atop the “wafer” (or substrate), from which these circuits are designed, also need to become thinner and thinner, allowing smaller and smaller elements (e.g., gates) to be squeezed into a given space. In particular, current designs are moving into the 0.15 to 0.1 micron range (i.e., the minimum horizontal width for an element). At the same time, the industry standard diameters of the semiconductor wafers are expanding from 200 mm to 300 mm. (These wafers are then typically cut into smaller pieces for use in the actual chips). [0006] In general, it has been conventionally important to accurately and expediently control the parameters used in the manufacture of wafers. For example, with regard to temperature, it is desirable to obtain temperature uniformity in the wafer during temperature cycling. Temperature uniformity provides for uniformity of aspects of the end-product wafer, such as layer thickness, resistivity, and etch depth. In addition, temperature uniformity in a wafer is necessary to prevent thermal stress-induced wafer damage such as warpage, defect generation and slip. Such control of temperature also becomes increasingly important as one attempts to increase the rate of wafer production (e.g., wafers per hour), since that requires the duration that the wafer is heated and cooled to be reduced (and, thus, the rates of temperature changes become more extreme). Also, it is often the case that the rapid temperature changes yield better results in the quality of the end-product wafer, as well. Other functions that may also require such control include pressure and the positioning of the wafer within the wafer processing chamber. [0007] Prior wafer processing facilities such as the RTP XEplus Centura and the HTF Centura (with, e.g., LPCVD Polysilicon chambers) from Applied Materials of Santa Clara, Calif. do provide some control of the various functions mentioned above in the course of controlling their wafer processing chambers. However, as critical dimmensions continue to shrink, it becomes increasingly important to more and more accurately and expediently control the functions used in their manufacture. With regard to temperature, for example, the smaller elements will not be created properly, and the wafer itself will be more prone to warpage, if the temperature is not uniformly and expediently controlled. [0008] In practice, it has been found that the control mechanisms of the prior wafer processing facilities mentioned above are unable to adequately fulfill the demands necessary to effectively manufacture the thinner films having greater diameters at the throughput required. For example, it has been found that the amount of information coming in from numerous sensors which must be analyzed and responded to quickly causes significant congestion on the various conduits (e.g., busses) of the computer processing system of the wafer processing facility, and that the constant interruptions that are placed upon the processor (due to, e.g., receipt of sensor information) tend to degrade from the performance of the computer processing system in its attempt to control the parameters of the wafer processing chamber. [0009] Consequently, what is needed is a scheme for responding to the increasing demands arising from the manufacture of the wafers described above such that the necessary functions can be observed and adjusted quickly and in accordance with a set of instructions (i.e., a “recipe”) dictating the requirements for the manufacture of such wafers. SUMMARY OF THE INVENTION [0010] The present invention solves the problems mentioned above by providing a system, method and medium for controlling a wafer processing chamber using two or more processors (within one or more computer processing systems), wherein specified functions are assigned to each processor. More specifically, some embodiments of the present invention contemplate that each processor has its own communications conduit (e.g., central bus), and that each may reside within its own computer processor system (each computer processor system being in communication with the other), wherein each computer processor system implements specified functions to control and maintain certain parameters involved in the manufacture of the wafer. This allows the present invention to react quickly to maintain rapidly-changing desired conditions within a wafer processing chamber and to maintain a greater degree of uniformity of those conditions throughout the wafer. [0011] Embodiments of the present invention contemplate that the wafer (referring hereafter to the end product wafer plus film) is manufactured in accordance with a recipe (which contains instructions and/or individual functions to be implemented within the wafer processing chamber). Consequently, a focus of at least some aspects of the present invention relates to ensuring that the instructions/functions in the recipe that are followed accurately and expediently. [0012] As indicated above, embodiments of the present invention contemplate that each processor within the one or more computer processor systems is assigned to oversee a particular function (e.g., temperature or pressure). Various embodiments of the present invention further contemplate situations where each instruction step contains multiple functions such as temperature and pressure (or some other situation where multiple functions can run concurrently), and that one of those functions is designated as “controlling.” For example, a given instruction step might indicate that both the temperature and pressure in a wafer processing chamber need to be increased, and also indicate that “temperature” is to be “controlling.” Then, the processor which is assigned to oversee temperature will be in control such that when the temperature reaches the goal indicated by the instruction step, the controlling processor will indicate to the other processors that the next instruction should be implemented, and will itself implement that next step. In this way, critical functions can be selected and implemented quickly and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS [0013] Various objects, features, and attendant advantages of the present invention can be more fully appreciated as the same become better understood with reference to the following detailed description of the present invention when considered in connection with the accompanying drawings, in which: [0014] [0014]FIG. 1 is a high-level flow diagram depicting the utilization of two processors to implement the wafer control functions contemplated by embodiments of the present invention. [0015] [0015]FIGS. 2 and 3 are flow diagrams depicting embodiments of the present invention where control during the implementation of an instruction is given to a selected processor. [0016] [0016]FIG. 4 is a high-level block diagram of functional modules as contemplated by embodiments of the present invention. [0017] [0017]FIG. 5 a is a block diagram of functional modules of an exemplary chamber controller. [0018] [0018]FIG. 5 b is a block diagram depicting a temperature measurement system as contemplated by embodiments of the present invention. [0019] [0019]FIG. 6 is a diagram depicting an exemplary wafer processing facility having four wafer processing chambers and five computer processing systems, as contemplated by embodiments of the present invention. [0020] [0020]FIG. 7 is a high-level block diagram depicting aspects of a computer processor system as contemplated by embodiments of the present invention. DETAILED DESCRIPTION [0021] The present invention relates to enhanced control of a wafer processing facility. More specifically, the present invention relates to a system, method and medium for the accurate and highly responsive implementation of one or more instructions/functions relating to the production of wafers in a wafer processing facility, and particularly for controlling one or more wafer processing chambers within a wafer processing facility. The present invention accomplishes this by utilizing two or more processors, which may reside in separate computer processor systems, wherein each processor and/or computer processor system is assigned to control, and sample information relating to, one or more designated functions (e.g., temperature, pressure, etc.). [0022] A process contemplated by embodiments of the present invention will now be discussed with regard to FIG. 1. Referring now to FIG. 1, the first step is that a given set of instructions (i.e., a “recipe”) that one or more wafer processing chambers within a wafer processing facility are to follow is accessed/loaded by the processors of one or more computer processing systems, generally, as indicated by a Block 102 . Embodiments of the present invention contemplate that the identical recipe can be loaded by all processors which will be used to implement the various specified functions of the recipe, though it is also contemplated in other embodiments that different related recipes may be accessed/loaded by each processor, where each recipe has information pertinent to the particular function that the processor as been assigned to perform. [0023] The next step is to wait for some indication that a wafer processing chamber has been (or will be) loaded, as indicated by a Block 104 . Thus, a signal is received that a wafer processing chamber has actually been loaded, or that one will be loaded in due course and to commence the recipe sequence. [0024] The next step is to obtain a next instruction/function in the recipe, as indicated by a Block 106 . In particular, the present invention envisions that instructions can contain multiple functions to be implemented and/or contain a single function. An example of a multi-function instruction might be, e.g., “lower the temperature to 600 degrees at 50 degrees per second and raise pressure to 780 Torr at 20 Torr per second.” (While the term “function” is used herein to denote both the general concept (e.g., “temperature control”) and a specific implementation (e.g., “raise the temperature 50 degrees), specific implementations can also be referred to as “commands.”) [0025] Once it has been determined which function(s) is to be implemented next, the next step is to determine which processor is to perform that function, as indicated by a case Block 108 . If the requested function to be performed has been assigned to the first processor, as indicated by a Block 110 , then performance of the requested function will commence using that first processor, as indicated by a Block 114 . Conversely, if the requested function to be performed is one assigned to the second processor, as indicated by a Block 112 , then performance of the requested function will commence using that second processor, as indicated by a Block 116 . [0026] It should be understood that FIG. 1's mention of the use of two processors is by way of example, and that the present invention also contemplates the use of more than two processors (within any number of computer processor systems) to implement (and be assigned) any number of different functions. Also, the present invention envisions that there are any number of ways for determining which processor should perform (or be assigned to) a given function. [0027] The present invention contemplates any number of embodiments (and combinations thereof) for determining when to discontinue implementing the current function(s)/instruction and obtain/implement the next one. In one exemplary embodiment, multiple functions (within, e.g., a multi-function instruction) are implemented using the different processors substantially simultaneously, and one or more (or all) of the functions can be selected as the “controlling” function, such that when the controlling function(s) reaches its stated goal, the next instruction is implemented regardless of whether any non-controlling functions have reached their goals. Thus, for example, if each instruction contains a temperature and a pressure function and only temperature is chosen as the controlling function, then when the desired temperature is reached, the next instruction is obtained and implemented even if the desired pressure stated in the previous instruction has not been reached. However, it may also be the case that each instruction contains only some of the possible functions which can be implemented, and thus if a subsequent instruction does not contain a function that would preempt a previously implemented function, at least some embodiments contemplate that the previously implemented function would be allowed to continue toward its set goal. Also, straight time limits can be set within an instruction (e.g., maintain the current temperature for 10 seconds). Of course, various other schemes are also contemplated, such as those involving sequentially implementing a stream of individual functions with various time limits associated with them, and the like. [0028] After the desired function(s)/instruction have been implemented (or commenced) as indicated above, the next step is to determine whether there are any more instructions/functions in the recipe to be implemented, as indicated by a decision Block 118 . If so, the next step is to obtain the next instruction/function in the recipe, as indicated by Block 106 . Otherwise, the recipe sequence ends, as indicated by a Block 120 . [0029] [0029]FIGS. 2 and 3 disclose a process contemplated by embodiments of the present invention where two computer processor systems (each having at least one processor) are used, and where one of the processors is given control during the implementation of an instruction, so that when the function being implemented by the controlling processor has terminated, the next instruction/function(s) of the recipe will then be implemented (with possibly the same or a different processor then being in control). In general, it is contemplated that more than one function is initiated at substantially the same time (via, e.g., a multi-function instruction), though other implementations are contemplated, as well (e.g., the functions are implemented at staggered time periods). [0030] Referring first to FIG. 2, this figure discloses the implementation of a recipe from the perspective of the first computer processor system. In FIG. 2, the first step is that the first processor system accesses or loads the recipe to be implemented, as indicated by a Block 202 . Before commencing implementation of the recipe, the present invention waits for the chamber to be loaded, or at least waits for to some indication that it will be loaded, as indicated by a Block 204 . This, in turn, signals the first processor to generate a “start” message (e.g., some indication that the recipe should now be implemented) as indicated by a Block 205 . Embodiments of the present invention, in accordance with FIGS. 2 and 3, contemplate that the first processor and second processor step through the same recipe instructions substantially simultaneously, and that it is the first processor that initially sends a signal to the second processor to commence implementation of the recipe upon the indication that the chamber has been loaded (or will be loaded). [0031] The next step is that the next instruction or function(s) in the recipe are obtained, as indicated by a Block 206 . Also indicated by a Block 206 is a determination as to which function is to cause the current instruction (or group of currently-implemented functions) to end once its set goal has been reached. [0032] The next step is to determine whether the end step function (determined in accordance with Block 206 ) is one that has been assigned to be performed by the first processor or the second processor, as indicated by a Case Block 208 . If it is determined that the end step function is to be performed by the first processor (e.g., the end step function is temperature, and the first processor has been assigned to control the temperature) then the first processor is given control (e.g., it determines when the current instruction ends and when the next one should be implemented) as indicated by Blocks 210 and 214 . Also as indicated by Block 214 , the first processor will perform the requested function, while the second processor may also be executing a function (where, e.g., the current instruction contains more than one function to be implemented). [0033] Once the function that is performed by the first processor has been completed, the first processor will indicate to the second processor that the next instruction/function is to be implemented by sending an “advanced step” message to the second processor, as indicated by a Block 222 . The first processor system, itself, will then determine whether there are more instructions/functions in the recipe that need to be implemented, as indicated by a Decision Block 218 , and if so, will obtain (and implement) the next instruction as indicated by Blocks 206 (and by the subsequent Blocks in the Figure). Otherwise, the recipe will end, as indicated by a Block 220 . [0034] Returning to Case Block 208 , if it is determined that the end step function is to be performed by the second processor, as indicated by a Block 212 , then the second processor is given control, as indicated by a Block 216 . Then, from the first processor's perspective, the first processor will wait for an “advanced step” message from the second processor (which will be received once the function performed by the second processor has terminated), also as indicated by Block 216 . Again, depending upon the instruction, the first processor may also execute a function. [0035] Referring now to FIG. 3, this figure is essentially a mirror image of FIG. 2, in that it is from the perspective of the second processor system. It should be noted, however, with regard to Block 305 , that it is contemplated that the recipe will be initiated by the first processor. [0036] With regard to FIGS. 1, 2, and 3 , it should be understood that the steps and the order of the steps are by way of example, and that the present invention contemplates that additional steps could be added, and/or certain ones omitted and/or the order of steps changed to implement aspects envisioned by embodiments of the present invention. Also, with regard to FIGS. 2 and 3, many of the embodiments discussed with regard to FIG. 1 are also applicable to FIGS. 2 and 3. [0037] An exemplary recipe that can be used with embodiments of the present invention is shown below, where the temperature is envisioned to be controlled by a second processor and all other functions are controlled by a first processor. Here, the recipe explicitly indicates which processor is in control, although it can also be determined by the step end condition: [0038] Step 1. [0039] Temperature Control: Open Loop, apply 25% power [0040] Pressure Control: Servo at 780 Torr [0041] Gas Flow: N2 5 Standard Liters per Minute [0042] Step End Condition: Temperature above 550 Degree C. [0043] Master (i.e., processor in control): Second Processor [0044] Step 2. [0045] Temperature Control: Stabilize Temperature at 550 Degree C. [0046] Pressure Control: Ramp Down to 700 Torr, 20 Torr per second [0047] Gas Flow: N2 5 Standard Liters per Minute [0048] Step End Condition: Pressure below 700 Torr [0049] Master: First Processor [0050] Step 3. [0051] Temperature Control: Ramp temperature to 1000 degrees C. at 180 degrees per second [0052] Pressure Control: Servo at 700 Torr [0053] Gas Flow: N2 5 Standard Liters per Minute [0054] N2 Bottom Purge 20 Standard Liters per Minute [0055] Step End Condition: Temperature above 1000 degrees C. [0056] Master: Second Processor [0057] Step 4. [0058] Temperature Control: Constant temperature at 1000 Degrees [0059] Pressure Control: Servo at 700 Torr [0060] Gas Flow: N2 5 Standard Liters per Minute [0061] N2 Bottom Purge 20 Standard Liters per Minute [0062] Step End Condition: By time: 10 sec [0063] Master: Second Processor [0064] Step 5. [0065] Temperature Control: Ramp temperature down to 800 Degree at 50 Degrees per Second [0066] Pressure Control: Servo at 700 Torr [0067] Gas Flow: N2 5 Standard Liters per Minute [0068] N2 Bottom Purge 20 Standard Liters per Minute [0069] Step End Condition: Temperature below 800 [0070] Master: Second Processor [0071] Step 6. [0072] Temperature Control: Ramp temperature down to 600 Degrees at 50 Degrees per Second [0073] Pressure Control: Ramp up to 780 Torr at 20 Torr per Second [0074] Gas Flow: N2 5 Standard Liters per Minute [0075] He 20 Standard Liters per Minute [0076] Step End Condition: Pressure at 780 Torr [0077] Master: First Processor [0078] END RECIPE [0079] [0079]FIG. 4 is a high-level diagram of functional modules utilized in a wafer processing facility (contemplated to be implemented primarily in software, but which can also be in whole or part implemented in hardware) used in embodiments of the present invention. It is envisioned that each of these functional modules is utilized (in some form) in conjunction with each of the processors, and thus the modules are part of (or at least accessible by) each computer processor system. (Thus, each of the modules is envisioned to be associated with each of the computer processor systems such that, e.g., each module may actually exist as separate entities, where each entity resides on one of the various computer processor systems.) Consequently, while the high-level functionality of each module may be used by the various processors, the actual lower-level implementation may differ with each processor (as will be seen in the example of FIG. 5 a ). [0080] For purposes of discussion, FIG. 4 contemplates the use of a first and second processor residing on a first and second computer processing system, respectively, for use in controlling four different chambers (chambers A-D). However, more than two computer processing systems (and processors per computer processing system) are also contemplated, each of which can control one or more assigned functions and/or be assigned to one or more chambers. [0081] Referring now to FIG. 4, each computer processor system is contemplated to have its own operating system, as indicated by Block 402 . Recipe/wafer Control Information 404 contains the recipe itself, as well as other information pertinent to the control of a wafer within a wafer processing chamber. [0082] As indicated above, embodiments of the present invention contemplate that the overall wafer processing facility can contain any number of wafer processing chambers, and FIG. 4 contemplates the existence of four wafer processing chambers (A-D), each of which is controlled by a chamber controller ( 406 , 408 , 410 , and 412 ). Again, like all of the functional modules depicted in the Figure, each chamber controller ( 406 - 412 ) is envisioned to exist, in some form, with regard to each computer processor system (and thus with regard to first and second processor). Embodiments of the present invention contemplate that each of these chamber controllers could access/be loaded with the same recipe, or they can each have a different recipe obtained from recipe/wafer control information 404 . [0083] Load lock controllers 414 and 416 are envisioned to control the loading and unloading of the physical wafer into and out of each of the wafer processing chambers (only A and B are shown for convenient reference). Also shown is a hardware interface 420 and user interface 418 . The hardware interface connects the computer processor systems with the actual wafer processing chambers for manufacturing the wafers. As will be appreciated by those skilled in the art, the specifics of the hardware interface will depend upon the particular interface characteristics of the wafer processing chamber being used. [0084] A more detailed diagram of each of the chamber controllers (e.g., 406 ), as envisioned by embodiments of the present invention, is now shown and described with regard to FIG. 5 a. Referring to FIG. 5 a, Block 502 depicts an exemplary embodiment of the chamber controller as it may exist on the first computer processor system, while a Block 518 depicts the chamber controller for a second processor system. In particular, and by way of example, it can be seen that the first computer processor system contains the recipe information (Block 504 ) and is in control of the safety tasks (Block 510 ) (e.g., checking to see if doors and covers are closed, whether any dangerous conditions exist, etc.), pressure control tasks (Block 512 ) gas flow tasks (Block 514 ) and magnetic levitation tasks (Block 516 ). The second processor system 518 , in this embodiment, is in control only of the temperature control tasks (as indicated by a Block 522 ). Embodiments of the present invention contemplate that the temperature control tasks 522 contain certain control algorithms, including taking a reading of the current temperatures within a wafer processing chamber (which was computed by Temperature Measurement System 520 , described below), comparing them to the current set point temperatures as well as future set point temperatures, and from that calculating the necessary voltages to send to the heat lamps (mentioned below) to heat the wafer. [0085] The chamber controller of the second processor system 518 is in communication with the chamber controller of the first processor system 502 via a communication link such as an RS 232 link. It could of course be any type of link, such as via Ethernet, or the like. In any event, it is contemplated that, through that link, the two processor systems interact as described above, and the second processor system receives recipe information. [0086] The chamber controllers of both the first and second processor systems each have a user interface ( 508 and 524 , respectively) and a hardware interface ( 506 and 526 , respectively). By having the temperature controlled by a separate computer processor system, as indicated in the Figure, the temperature can be more accurately and quickly responded to, maintained and manipulated. In this way, a temperature measurement system 520 , for example, can be more effectively utilized in order to accurately and quickly measure the temperature at various portions of the chamber, so that desired changes to the temperature of the chamber can be implemented quickly and uniformly. Thus, the heat lamps 528 can be controlled more effectively to quickly and precisely react so that very thin film layers (and elements) can be successfully manufactured. In particular, embodiments of the present invention contemplate that, within a given wafer processing chamber, heat lamps 528 are made up of multiple individual lamps, each for heating a particular portion of a given wafer, and each of which is individually adjustable to fine-tune the temperature of that particular portion, and thus collectively across the entire wafer. [0087] It should be understood that the division of functions as shown in FIG. 5 a is by way of example, and that, for example, any number of different schemes and scenarios could be implemented whereby more than two processor systems (and more than two processors) are utilized, each controlling one or more separate functions. [0088] A more detailed depiction of temperature measurement system 520 is described with regard to FIG. 5 b. Referring now to FIG. 5 b, embodiments of the present invention envision the use of (and/or use in environments with) optical systems 550 as part of (or used in conjunction with) a wafer processing chamber controlled by the present invention. Specifically, embodiments of the present invention contemplate that the temperature of the wafer is detected as a function of the light emitted due to being heated. To more accurately detect the emitted light (and thus, the heat) over different portions of the wafer, multiple optical systems (in this example, eight) are used. In this way, the present invention can detect variances in temperature at different portions of the wafer. The present invention can then cause the intensity of certain heat lamps affecting different portions of the wafer to increase or decrease (and/or cause the flow of cooling gases to vary in amount and/or type and/or flow to different portions of the wafer). It is also envisioned that the optical systems 550 serve to allow only selected wavelengths to enter, so that a more accurate reading of the temperature can be ascertained. [0089] Of course, it should be understood that any number of other different types of schemes for detecting temperature are also contemplated by embodiments of the present invention, in addition to those that detect light. [0090] Preamplifiers 552 serve to convert the current that are received by the optical systems 550 into voltage (on a scale of 0 to 5 volts) while the probes 554 , which are digital signal processing filters, remove noise and also serve as A to D converters (One example of probes 554 is the T320C2xLP chip from Texas Instruments). [0091] From the probes 554 , the voltage is applied through a temperature interface block 556 , and the measurement of the voltage is then analyzed by a linearization algorithm 558 which, depending upon the received voltage, determines the temperatures of each portion of the wafer observed by one the optical systems 550 . Embodiments of the present invention contemplate that the linearization algorithm 558 utilizes a look-up table using some interpolation, wherein the values of the look-up table are implemented based upon the particular material used in the wafer. That is, different substances will give off different amounts of light when heated, and thus the values in the look-up table must be set accordingly. [0092] [0092]FIG. 6 depicts an exemplary wafer processing facility disclosing features of, and/or environments encompassing, embodiments of the present invention. In this example, four wafer processing chambers and five different computer processor systems are utilized. Referring now to FIG. 6, a first computer processor system 601 is shown having a user interface 602 as well as a communications mechanism 603 and 604 for communicating with chambers 609 . In addition, serial communications 605 and 606 are shown to be in communication with the second computer processor systems 607 . Here, there are shown to be four separate second computer processor systems 607 . While one second computer processor system is shown for each wafer processing chamber, it should be understood that the present invention also contemplates that, instead of four, less (or more) than four could also have been used to control the four chambers 609 (and, in fact, embodiments of the present invention event contemplate that a single computer processing system having at least two processors could be used in lieu of the five computer processing systems shown in the Figure). Lastly, the second computer processor systems 607 are shown to be in communication with the wafer processing chambers 609 via communication links 608 . [0093] An exemplary combination of computer processor systems and chambers can be found in the Radiance Centura device from Applied Materials. [0094] Exemplary components of a computer processing system used in conjunction with the present invention is now shown with regard to FIG. 7. Referring now to FIG. 7, a recipe executor 708 (representing software or the like having the functionality described herein) is shown to reside in a memory/storage device 706 . It is also contemplated that instructions/functions can be stored as part of recipe executor 708 and/or as part of memory/storage device 706 and/or can originate from communications I/O 712 (mentioned below). Embodiments of the present invention contemplate that the memory/storage device 706 could be any number of different types of computer-readable mediums for storing information, including RAM memory, magnetic, electronic, atomic or optical (including holographic) storage, some combination thereof, etc. [0095] Memory/storage 407 is shown as being in communication, via communication link 702 (e.g., a bus), with one or more processor(s) 704 . Embodiments of the present invention contemplate that the processor(s) 704 can be those typically found in the computers mentioned below, or they can be any number of other types of processor(s). [0096] In addition, display device and user interface 710 (e.g., a mouse, keyboard, and/or modem) are shown. Communications I/O 712 serves to communicate with wafer processing chambers and other computer processing systems, and in FIG. 7 is shown to be in communication with processor(s) 704 and memory/storage 706 . [0097] The present invention further contemplates that communications I/O 712 can serve to receive various transmission schemes such as those relating to telecommunications, cable or other transmission mechanisms, and that at least some of the aspects of recipe executor 708 can, in whole or part, be a transmission. Thus, for example, at least some aspects of recipe executor 708 that would otherwise originate from memory/storage 706 could instead originate from communications I/O 712 (e.g., the medium from which the recipe executor 708 originates can be a transmission). [0098] It should be understood that the configuration of the various aspects of the present invention depicted by FIG. 7 are by way of example, and at the present invention contemplates any number of different configurations and/or different components. [0099] With regard to the various specific components contemplated for use with regard to aspects of present invention as depicted by FIG. 7, one exemplary embodiment includes the use of a Motorola 68000 series processor such as the 68040 processor (from Motorola of Schaumberg, Ill.) for use with a first computer processor system (where e.g., the functions described with regard to Block 502 of FIG. 5 a are being controlled) using the “Boss” operating system from Applied Materials or the VRTX operating system from Mentor Graphics Corporation, of San Jose, Calif. For the second computer processor system where, e.g., temperature is being controlled (described with regard to Block 518 if FIG. 5 a ), an exemplary operating system is also the VRTX operating system using any number of different types of Pentium processors from Intel Corporation of Santa Clara, Calif. Of course, it should be understood that any number of different types and combinations of processors and operating systems could also be used with either of the computer processor systems. [0100] In general, it should be emphasized that the various components of embodiments of the present invention can be implemented in hardware, software or a combination thereof. In such embodiments, the various components and steps would be implemented in hardware and/or software to perform the functions of the present invention. Any presently available or future developed computer software language and/or hardware components can be employed in such embodiments of the present invention. For example, at least some of the functionality mentioned above could be implemented using the C, C++, or Pascal or any assembly language appropriate in view of the processor(s) being used. It could also be written in an interpretive environment such as Java and transported to multiple destinations to various users. [0101] It is also to be appreciated and understood that the specific embodiments of the invention described hereinbefore are merely illustrative of the general principles of the invention. Various modifications may be made by those skilled in the art consistent with the principles set forth hereinbefore.	A system, method and medium for controlling a wafer processing chamber using two or more processors (within one or more computer processing systems), wherein specified functions are assigned to each processor. Some embodiments contemplate that each processor may reside within its own computer processor system (each computer processor system being in communication with the other), wherein each computer processor system implements specified functions to control and maintain certain parameters involved in the manufacture of the wafer. This allows the present invention to react quickly to maintain rapidly-changing desired conditions within a wafer processing chamber and to maintain a greater degree of uniformity of those conditions throughout the wafer.	6
BACKGROUND OF THE INVENTION The invention concerns an improved self-retaining roof bolt. Roof bolts are used in underground mining operations to help support tunnel roofs. Present practice is to drill an approximately 1-inch diameter hole 4 to 6 feet into the tunnel roof. Holes are usually drilled about every 2 feet. The hole is first filled by inserting a rod into the hole and then the face is sealed with a plate. The space between the rod and the wall of the hole is then filled with a cement or resin securing the rod and plate. The need to support the bolt in the hole until the rod is secured by the cement or resin significantly slows the installation of new bolts and increases the cost of each bolt. For instance, the total in-place cost in a typical mining operation has been estimated at about $12 per bolt, approximately 25% of the total mining cost. Accordingly, a system which might reduce the cost of in-place roof bolts would provide significant savings. One means of reducing the cost of installing roof bolts would be to provide a bolt which does not require external support during the cementing process. SUMMARY OF THE INVENTION This invention provides an self-retaining roof bolt and method of installation. The roof bolt, described in detail hereinafter, comprises: (1) an elongated U-shaped member having a pair of spaced leg sections depending from the connected portion of said U-shaped member, said leg sections being formed to support a flat plate fitted over said U-shaped member; (2) a coat of grouting on said U-shaped member which maintains said leg sections under transverse tension at ambient temperature, said grouting being malleable at elevated temperature; (3) a flat plate member having an opening therein positioned over said U-shaped member and supported by said leg sections, said opening being large enough to permit said leg sections to move transversely on release of said transverse tension to maintain said U-shaped member in place of a roof hole; and (4) a gasket member abutting said flat plate member and in sealing engagement with said U-shaped member to prevent flow of said grouting below said plate member at elevated temperature. In its method embodiment, this invention provides a method for installing the above-summarized roof bolts by inserting a bolt in a roof hole, and momentarily heating the leg sections. This elevates the temperature of the grouting which becomes malleable releasing the tension on the legs and allowing them to separate and wedge against the roof hole walls. BRIEF DESCRIPTION OF THE FIGURES The Figures show preferred embodiments of the roof bolt of this invention in partially cut-away perspective view. DETAILED DESCRIPTION OF THE INVENTION The present invention concerns a self-retaining roof bolt comprising four members. Each member of the bolt serves a necessary function, but none of the members is restricted by its function to a particular material or configuration. Accordingly, there are numerous embodiments of the invention which will become apparent from the following detailed description. The first member of the roof bolt is an elonaged U-shaped member having a pair of spaced leg sections depending from the connected portion of the U-shaped member. The leg sections are formed to support a flat plate fitted over the U-shaped member. Referring to the embodiment illustrated in FIG. 1, elongated U-shaped member 1 has depending leg sections 5 with their free ends 6 bent in opposing directions at an angle of approximately 90° to the longitudinal centerline of the U-shaped member to support plate 3. The member is U-shaped by virtue of connection 7, at the closed end of the bolt. Alternative suitable configurations for the U-shaped member are readily apparent. For example, referring to FIG. 2, elongated U-shaped member 1 has depending leg sections 5 with spurs 6 to support plate 3. The configuration can be varied so long as the member has at least two leg sections which can be maintained under transverse tension, and are formed to support a flat plate fitted over the member. The closed end can be, for example, connected by a spot weld as in FIG. 1 or by a continuous bend as in FIG. 2. The material chosen for use in the construction of the U-shaped member should be capable of withstanding both shear forces and compression forces. The strength of the bolt will depend primarily upon the strength of this member. The material should also be one which can be formed in a U-shape and placed under tension by compressing the leg sections. In addition, the material should have a heat-transfer coefficient which insures that the leg sections can be readily heated and will transfer sufficient heat to readily elevate the temperature of the grouting, causing it to become malleable, thereby releasing the tension on the leg sections. Suitable materials include metallics such as steel rebar or aluminum rod. Fiberglass rods can be used in conjunction with the heat-conducting metal to reduce weight. Steel rebar is a preferred material due to its availability and superior shear resistance. The second member of the roof bolt is a grouting coat which is applied to the leg sections of the U-shaped member and maintains the leg sections of the U-shaped member under transverse tension at ambient temperature. Referring to the Figures, grouting coat 2 must be sufficiently firm at ambient temperature to maintain tension on the U-shaped member, but must also become malleable when heated to allow installation by releasing the tension on the leg sections of the U-shaped member. It is also desirable for the grouting to have some adhesive properties. Such groutings serve to cement the roof bolt in position. Thus, when the grouting is heated and becomes malleable, the leg sections of the U-shaped member wedge against the wall of the roof hole retaining the bolt in position; and then, as the grouting cools it forms to the hole cementing the bolt in place. A variety of suitable grouting materials are known in the art. The sulfur-based coating compositions and foams described in U.S. Pat. No. 4,026,719, which issued from application Ser. No. 631,781, and U.S. Pat. No. 3,892,686, which issued from application Ser. No. 344,694, respectively, (the disclosures of which are incorporateed herein by reference) are particularly useful. Other suitable groutings include, for example, thermoplastics such as the polyethylenes, polypropylene, acrylic resins, nylons, acetal resins, polyurethane resins, and the like. The properties of these and other suitable thermoplastics are thoroughly described in "Polymer Handbook", Brandrup and Immergut (Eds.), Interscience Publishers, 1966, at pages IX-1 through IX-7. The U-shaped member can be coated in any number of ways. In general, the free ends of the leg sections of the U-shaped member are compressed to put the leg sections under transverse tension; and the leg sections are then sufficiently coated to maintain them under tension at ambient temperature. The grouting can be applied as a liquid by melting it and pouring or spraying it around the U-shaped member, which is being held in a suitable mold. When a sufficient thickness is obtained, the coating is allowed to cool and solidify. Alternatively, the coat can be pre-cast as a sleeve, and then slipped over the U-shaped member while it is under tension. This latter method requires care to insure that the hollow core of the pre-cast sleeve of coating is correctly sized to hold the leg sections of the U-shaped member under tension. The coating is preferably not applied to the portion of the U-shaped member which is formed to support the flat plate since it will extend beyond the roof hole. The viscosity of the coating when heated is preferably adjusted to prevent the coating from running into openings or cracks in the roof hole so far as to consume too much of the coating to permit filling as much of the hole as possible. On the other hand, the coating must not be so viscous when heated to prevent flow to obtain adequate contact with the hole surfaces. The final members of the roof bolt are the plate member and flexible gasket member. The gasket member and plate member abutt to form a seal which prevents the grouting from flowing out of the roof hole when heated. Referring to the Figures, plate 3 and gasket 4 have centrally located holes and are positioned over the coated U-shaped member resting on the leg sections of the U-shaped member. The gasket engages both the plate and the coated U-shaped member to seal the gaps between the plate and the U-shaped member. In a typical embodiment of the roof bolt, the plate and gasket members are positioned to complete the bolt after the U-shaped member is coated and its leg sections are under transverse tension. Alternatively, the gasket and plate members can be positioned around the U-shaped member prior to coating. The hole in the plate must be large enough for the leg sections of the U-shaped member to separate when the restraining force is released, i.e., grouting is heated, and wedge against the walls of the roof hole. The gasket, obviously, seals the hole. The shape and relative size of the plate are not critical. Similarly, the plate, while typically steel, might also be wood, plastic or other metallic alloy. As an alternative embodiment, several flexible strips might be attached at or near the top of the U-shaped member, somewhat like an umbrella frame. These strips would further secure the bolt. Similarly, the U-shaped member could be fashioned with barbs or bends, as in FIG. 2, to aid in securing the bolt. Such embodiments would reduce the burden on the leg sections of the U-shaped member to initially secure the bolt. The roof bolt is installed in a roof hole by inserting it in the hole and heating the exposed portion of the leg sections of the U-shaped member long enough to elevate the temperature of the grouting causing it to flow. Where the free ends of the U-shaped member are exposed, heating can be done by passing a high amperage, low voltage current through the U-shaped member of the bolt. Alternatively, heating can be accomplished by a direct flame. When heated, the grouting will flow by gravity to fill voids between the hole and the bolt. At the same time the restraining force exerted by the grouting on the leg sections of the U-shaped member will be released and the leg sections will separate and wedge against the sides of the hole. Thus, the roof bolt is held in the hole without the use of a support until the grouting cools and resolidifies cementing the bolt in place. It can be seen that during installation of the bolt, the grouting coat will drain downwardly in order to fill the cavity. Depending upon the volume of the void spaces to be filled, the portion of the U-shaped member which is exposed at the inserted end will vary. In order to minimize this exposure, it is preferable to have a close tolerance between the bolt size and the hole size.	A self-retaining roof bolt comprising an elongated U-shaped member having a pair of spaced legs which support a flat plate fitted over the U-shaped member and are held under transverse tension at ambient temperature by a grouting which becomes malleable at elevated temperatures. The roof bolt is installed in a roof hole by momentarily heating the leg sections, which causes the grouting to soften, releasing the tension on the legs and allowing them to separate and wedge against the roof hole walls. Thus, the bolt retains itself in the roof hole while the grouting cools. Upon cooling, the grouting re-solidifies, firmly securing the bolt.	4
This application is a division of application Ser. No. 06/792,745, filed 10-30-85 now U.S. Pat. No. 4,796,782. BACKGROUND OF THE INVENTION The present invention relates in general to an ink monitor system and pertains, more particularly, to an improved system for monitoring the weight of ink consumed, particularly as it relates to a high-speed, web-fed printing operation. Continuous high-speed web-fed printing presses produce printed product at a very high rate. They also consume materials, primarily ink and paper, at a very high rate. While the gross consumption of ink can be determined after the fact by examining the amount of ink purchased less that remaining in inventory or the number of cans, barrels, etc. consumed in the course of a week or a month, there is no effective way of measuring ink consumption and allocating that consumption accurately to the various points in the printing process at which ink is consumed. To understand the problem, one can consider a typical ink-consuming machine, a web offset printing press. The press comprises a paper supply, usually in the form of a roll stand and automatic splicing device that provides paper to the press continuously from a sequence of paper supply rolls. A web tensioning device and a sequence of printing units, usually not less than four nor more than eight, print images of different colors on the web in succession. At the end of the printing units is equipment for causing the ink to set and for either rewinding the product or dividing the web into individual products through a combination of folding and cutting processes. Each printing unit has two lithographic plate cylinders, each of which is coupled with a blanket cylinder for the purpose of transferring an inked image from the plate to the paper. The two blanket cylinders have surfaces of a resilient rubber-like characteristic and engage each other along a nip, through which the paper passes and, in so doing, have the inked images from both blanket cylinders transferred to its surface. The plate cylinders carry plates having the image information on their surface in the form of differentiated wetting properties for oil and water. In rotating from one engagement with the blanket cylinder to the next, an element of the plate cylinder first moves under the dampening system which places a thin, uniform film of water on all parts of the plate cylinder that are susceptible to being wetted. It then passes under the ink system. A second series of rollers delivers a uniform, thin film of ink to those areas of the plate that have been sensitized to receive ink and reject water. The source of ink is a tray disposed crosswise of the web, one side of which is formed by or supports a roller. The bottom of the tray has a thin plate or a blade, having an adjustable clearance with the roller, so that as the roller turns, it has deposited upon it a film of ink whose thickness is controllable by adjusting the blade clearance. The blade may be flexible, or formed of segments, to print differential control of ink film thickness across the web. The ink, so supplied to the roller, is delivered through a series of contacting rollers to the plate. The quantity of ink delivered to the plate may be varied by adjusting the ink film delivered to the fountain roller. In the printing process, the fountain blade is adjusted so that the ideal amount of ink is delivered by the fountain to produce the correct color density in the printed image. In practice, however, the amount of ink delivered may vary from the ideal. And while a deficiency of ink is usually readily apparent, an appreciable excess can be delivered without greatly affecting the image quality. Thus, it is desirable to measure directly the quantity of ink being applied at each fountain. In setting prices for printing work, it is necessary to estimate total quantities of paper, ink, labor, and press time to be consumed in completing the job. In the performance of the work, it is also desirable to measure the actual quantities used in order to compare with the estimate, to determine the profitability of the particular job and the accuracy of the estimating procedure. While means exist for the measuring of time, labor, and paper consumption, the measurement of ink consumption is a much less satisfactory procedure, especially when ink is supplied continuously to a multiplicity of jobs by pumping from large tanks. Ink is bought by the pound and has a variable density so volumetric flow meters offer a poor approximation to the ink used. Accordingly, it is an object of the present invention to measure accurately the total quantity of ink delivered to each job, for each color used, and to indicate the rate of pounds of ink consumption at each consuming point associated with the press. Existing systems for the measurement of ink consumption typically rely on metering devices in the ink lines supplying a whole press. When displacement-type meters are used, it is necessary to convert the volume of ink used to weight, using the density of the ink. However, ink densities vary widely, not only from color-to-color, brand-to-brand, and lot-to-lot within a brand, but also the ink drawn from a given container may vary in density, so that even if each ink container is sampled, the method is still inaccurate. A true mass rate flowmeter would overcome this, and attempts have been made to employ so-called mass sensing meters but without success. Even if a mass rate meter compatible with inks were to be developed, it would suffer from the drawback of all feed line metering systems; the inability to attribute the ink to the individual consuming points to know how much was used at each fountain. While this could theoretically be overcome by use of a mass rate flowmeter at the line feeding each individual fountain, the number of meters so required would be large, and the system uneconomic as a result. Accordingly, it is a further object of the present invention to provide indication of the weight of ink consumed at each fountain of a web offset press having many such fountains and to provide the indication of weight, independent of density variations in the ink, and without requiring that sensors be installed at each fountain. A further object of the present invention is to provide an ink monitor system for indicating the rate of ink consumption in weight of ink per thousand printed products at each ink consuming position in the press. Still another object of the present invention is to provide an ink monitor system that provides a remote indication of the amount of ink in each tank in use for supplying ink to the press. Another object of the present invention is to provide an ink monitoring system having alarms when the ink has reached a predetermined low level so that provision of a replacement tank can take place. SUMMARY OF THE INVENTION To accomplish the foregoing, other objects, features and advantages of the invention there is provided a system for monitoring an ink flow from an ink storage tank to at least one ink consumption point which is typically an ink fountain of a high-speed, web-fed printing press. The system typically includes at least one press with each press comprised of a number of press units and with there typically being a plurality of storage tanks, each containing a different color ink. In accordance with the invention, a scale means is provided for measuring the weight of the ink storage tank with the stored ink therein, and for providing a continuous signal representative of measured weight. There is a pump means associated with the storage tank for pumping the ink to the fountain including coupling lines to the fountain. Each pump may actually service one or more tanks and in accordance with the invention has associated therewith, a means for sensing a volume flow of ink delivered. An ink sensor means is provided for detecting the level of ink in the fountain and for providing an ink demand signal when the level of ink in the fountain falls below a predetermined level. Valve means are provided in ink coupling means for controlling ink flow to the fountain. Control means is responsive to this demand signal for operating the valve means to cause ink flow to the fountain. Thus, in accordance with the invention, it can be seen that rather than trying to provide some type of weight flow meter in the coupling lines, a scale means is provided for measuring the tank and ink therein. Means are then provided for comparing the weight signals from the scale at successive times to determine the weight of ink consumed over the interval between readings. This thus readily provides a weight indication of weight consumed in a particular tank. The associated scale means can be of conventional design and can be of relatively simple construction, yet providing an effective reading. By taking an initial reading when the tank is first disposed on the scale, then any subsequent readings will indicate only ink consumption as the other weights on the scale do not change. In accordance with the invention there is also provided a means for measuring volume flow in the ink coupling line. This is provided primarily in connection with now determining, not only total ink consumption, but also ink consumption on the basis of each individual ink consuming point which in the illustrated example, is an ink fountain associated with the printing press unit. In this regard, there is thus provided a means for controlling delivery to only one fountain at a time. This means is described herein as being provided in alternate embodiments. In one embodiment, the means for controlling delivery to the fountain is on the basis of time slot allocation. In an alternate embodiment to the invention, it is accomplished on the basis of demand priority queue. By now, limiting flow at any particular time to only one fountain, the electronics can thus detect the volume flow only during this single fountain delivery. Means are provided for cumulatively counting the volume measurements associated with a particular fountain to thus determine total ink consumption allocated to that fountain. In accordance with the invention, the means for measuring volume may comprise a pump stroke position sensor that measures pump strokes or fractions thereof. This is used in association with means for determining the sensor incremental weight delivery per stroke. Means are provided for totaling the number of pump strokes to provide a volume reading, and furthermore means are provided for establishing an estimated pump constant in pounds per stroke to provide a density reading. These two readings are multiplied in order to determine the weight consumed at a fountain. Because of changes in pump calibration, ink density, and other factors, the total ink consumption as measured by pump strokes (volume) probably differs from the total weight loss from the ink tank as measured by the scale. When the system is operated long enough, so that the uncertainty of weight measurement is a small fractional percentage of the total ink weight pump, then a reconciliation is performed by determining the difference between pump stroke summation weight estimate and weight lost from the tank. The difference is distributed proportionately among the ink consumption estimates. Thus while the system accuracy may be relatively low over short periods of operation, it becomes more and more accurate as operation continues. Such reconciliations may occur at different points in the system measurement. BRIEF DESCRIPTION OF THE DRAWINGS Numerous other objects, features and advantages of the invention should now become apparent upon a reading of the following detailed description taken in conjunction with the accompanying drawing, in which: FIG. 1 is a block diagram of a preferred embodiment of the ink monitor system of the present invention; FIG. 2 is a schematic diagram of the ink monitor system shown in association with two presses each comprised of eight units; FIG. 3 is an electronic block diagram of the ink monitor system; FIG. 4 is a schematic cross-sectional diagram illustrating the fountain arrangement and associated components; FIG. 5 is a schematic block diagram illustrating control in accordance with the electronics of the invention; FIG. 6 is a further block diagram illustrating a time slot allocation technique for fountain enabling; FIGS. 7 and 8 are block diagrams illustrating a demand priority system for fountain enabling; and FIG. 9 is a block diagram showing cumulative counters that are employed in providing total consumptions on a per fountain basis. DETAILED DESCRIPTION Reference is now made to the drawings and in particular FIG. 1 which is a schematic diagram of the ink monitor system of the invention. Reference may also be made to the associated schematic diagram of FIG. 2 which illustrates the use of eight separate ink tanks for servicing two presses identified in FIG. 2 as press A and press B, each of which may comprise eight press units. In the ink monitor system, ink is supplied to the press from large tanks 10, one for each color in use. In the schematic diagram of FIG. 2 it is noted that there are eight separate tanks. The ink is moved from the tanks to the press by the use of ink pumps which are normally pneumatically operated and that pump ink on demand. FIGS. 1 and 2 show these pneumatically operated pumps 12. The pumps 12 maintain the ink under pressure for delivery to the delivery lines of the press. In this regard, note in FIGS. 1 and 2 the ink delivery lines 14. In FIG. 1 note the press units 16 to which are coupled the ink delivery or feed lines 14. Whenever a delivery point is opened so that ink can flow, the pressure causes ink to flow and the ink pump 12 strokes so as to feed ink into the lines 14 to the consuming point for long as the delivery point is open. In this regard, note in FIG. 1 the ink delivery valve 18 in the feed line 17. The ink valve 18 controls ink delivery to each of the respective fountains 20. FIG. 1 also shows associated with each pump 12, a pump sensor 13 which senses the volume flow of ink delivered. Connected from each pump 12 and between the pump and tank are associated hoses 11. Individual valves may be provided in each of the hoses 11. The ink pump 12 may be mounted on the floor adjacent to the ink tank 10, being connected to the ink tank by the suction hoses 11. In an alternate embodiment, the ink pump 12 may be physically mounted to the top of the ink tank with the pump inlet immersed in the tank interior. Ink from the ink pump is delivered by a flexible line to the ink distribution piping or lines 14 supplying the fountains 20 of one color on one or more presses. An air hose not described in the drawings, supplies pressure to the top of each tank for the purpose of causing a follower plate (not shown) to move down the tank as ink is consumed to prevent formation of voids and to prevent ingestion of air into the ink system. To attain the object of measuring the weight of ink delivered, the ink tank is placed on a scale 24 that continuously monitors the total weight of tank, ink, and any part of the pump and delivery system that is mounted on the tank. As ink is consumed from an initially full tank, the weight on the scale decreases. The total decrease in weight is the total ink consumption to a very high degree of accuracy. Thus, to determine the total ink consumed from any tank during the course of a job, a shift, a day, or any other period of time, it is necessary only to take the difference between the starting and ending tank weights. When a tank of ink empties, the valves at the output of the tank are shut off. The empty tank is removed and a full tank placed on the scale and connected with the pump. The ink consumption measuring system requires no operator intervention at a tank change, because the system detects the events connected with the tank exchange as follows. When the tank is to be changed, the first event is the disturbances of the weight resulting from operators uncoupling the ink supply and air hoses. The system requires that a succession of scale readings be equal within a narrow preset tolerance range before a reading is accepted for purposes of computation of ink consumption. The disturbances associated with disconnecting one tank and reconnecting another prevent the system from accepting as valid any indications of ink consumption and any readings during the period of such disturbances. Furthermore, when the ink tank is removed usually by a fork truck, the weight of the scale decreases rapidly to a value near zero. When this indication has fallen below a preselected value intermediate the weight of an empty ink tank and an empty scale, the system recognizes that an ink tank has been removed. When a new ink tank has been placed on the scale, and a number of successive weight readings within the established tolerance range have been obtained, then the system registers the full total weight. The act of coupling air and ink hoses disturbs the scale reading again, and during the period of disturbance, no further weight indications are recorded by the system. However, when the attachment process is complete, again, a succession of substantially equal readings is obtained, and the system records the weight of the full tank as modified by the attached air and ink hoses. In connection with the foregoing discussion, reference is now made to FIG. 5 which is a block diagram illustrating the manner in which automatic weight registration of ink consumption occurs. FIG. 5 shows the scale 24 which may be considered as having an analog signal output with the level of the signal corresponding to the weight that is being sensed. FIG. 5 also shows in the block diagram, a timer 26, a sample and hold circuit 28, store 30, and comparator 32. There is also included a threshold detector 34 along with two further sample and hold circuits 36 and 38. There is also provided a comparator 40 and a second comparator 42. It is noted that the analog output from the scale 24 is coupled to a number of circuits for providing some of the detection features previously set forth. The idea is to have an output reading only of ink consumption not effected by other weight changes that occur by virtue primarily of removal and replacement of the tank. For this purpose, the system detects first, a full weight indication when the tank is first placed on the scale and then at the time that the tank is removed, or just before it is removed, a minimum weight reading is taken with the difference in these two weights indicating ink consumption associated with that particular tank. As indicated previously, when the tank is on the scale and is undisturbed, there will be a series of readings that can be taken that will fall within a narrow preset tolerance range. This assumes that the tank is not being disturbed. The circuitry for detecting this includes the sample and hold circuit 28, timer 26, store 30, and comparator 32. The sample and hold circuit 28 looks at the readings from the scale 24 and the holding of the signal occurs by virtue of the output of the timer 26. The timer 26 operates at some predetermined rate so that successive readings can be taken, stored and held, and then subsequently stored in the store 30. The store 30 may be a register that stores the successive weight readings in either analog or digital form. The series of readings are illustrated as multiple outputs at the output of the store coupled to the comparator 32. The comparator 32 examines each of these successive readings and then determines whether the tank is being disturbed or not. This is indicated at the output of the comparator 32 by the signals STABLE or UNSTABLE. The STABLE signal in FIG. 5 indicates that the readings are all within a preset tolerance range. If any of the readings fall outside of this range, then the signal is unstable. FIG. 5 also shows the threshold detector 34 which couples from the signal line 25 and also has a threshold input identified as input TH. The detector 34 basically has two outputs, one indicating a tank removed and the other indicating a tank on the scale. These are indicated as outputs TR and TO, respectively. The line 25 also couples to the sample and hold circuit 36. The hold or latch input to the circuit 36 is from the AND gate 31 which receives the tank on signal and also the stable signal. Thus, when the full tank is replaced on the scale, the signal TO is generated and after all of the couplings and lines have been connected, the signal STABLE occurs. This causes a latching of the weight signal indicated as a full weight signal at the output of the circuit 36. This signal couples to the comparator 40 at one input thereof. Also, there is a coupling of the signal on line 25 to the other sample and hold circuit 38. This circuit is latched by virtue of a signal from the AND gate 33. This receives two signals, one which is the signal TO and the other the signal UNSTABLE. This circuit is meant to indicate that when the tank is still on the scale, but there is an indication of instability, then the sample and hold circuit 38 is latched to indicate a minimum weight. It is noted also that the analog weight on line 25 is continuously monitored by the comparator 42 which may also receive the full weight signal. Thus, the output of the comparator 42 provides a continuous weight differential indicating continuous readings of ink consumption. In this regard, it is noted that in another arrangement, the output of the gate 33 may also be used to set a circuit that would then look at the just previous analog weight to determine minimum weight. The assignment of ink consumption to the individual fountains occurs as follows. The basic ink distribution system operates on demand. Ink flows at any fountain level controller when it is called for and the ink pump operates as required to supply the various ink consuming points. If several of the multiple ink consuming points are drawing ink at any given moment, it is not possible to tell how much ink is actually being consumed at any one point. Because the actual rate of ink consumption at any fountain is only a small fraction of the delivery rate of the pumping system, however, it is possible to limit delivery to one fountain at a time. Enabling one fountain at a time may be accomplished by either of two methods: by time slot allocation or by demand priority queue. In time slot allocation, each fountain is enabled for a certain period, say 30 seconds, in sequence. If its level controller is calling for ink at that time, the fountain will be replenished. If it is not, the time slot will pass with no ink flow occurring. This system has the virtue of great simplicity and requires no information from the fountains to the ink weighing system in order to function. It has the drawback that it does not make efficient use of the capacity of the ink supply system to deliver ink in that several fountains may be demanding ink at a point when the system has enabled another fountain that does not require any ink during that time slot. With regard to the delivery of ink to the fountain, reference may now be made to FIGS. 4 and 6. FIG. 4 shows the fountain 20 with associated roller 21 and aforementioned blade 19. FIG. 4 also shows the level sensor 45 and the control valve 18. The level sensor 45 may be of conventional design and simply provides a demand signal to the computer 50 requesting pumping of ink to the associated fountain. Now, on a time slot allocation basis, reference may be made to FIG. 6 which shows signals T1, T2, T3, down to TN. These signals may each be of the aforementioned 30 second duration and may be separated from each other. FIG. 6 also shows a series of detectors 47 each receiving the timing signals and also a level sensor signal identified in FIG. 6 as the signals L1, L2, L3, and LN. This indicates that during time slot Tl, if the level sensor L1 is making a demand because the fountain has to be filled, then the detector 47 associated therewith gives an output that essentially operates the valve 18 at the fountain. FIG. 6 shows these valves F1, F2, F3, and FN. Thus, if during a particular time slot the level controller is calling for ink at that time, the fountain is replenished. As mentioned previously, the time slot allocation technique has the drawback of inefficiency. The demand priority system overcomes this problem. To effect it, a signal is brought from each fountain to the ink weighing system to indicate to the ink weighing system when each fountain is demanding ink. In this regard, refer to FIG. 7 which shows the input request signals from the level sensors identified as signals L1-L4. These couple to a priority controller 50 with the outputs thereof being coupled to the individual control valves associated with each fountain identified by the reference characters F1-F4. Reference is also made to FIG. 1 which shows the level sensor signals from the ink fountains as lines 52 coupling from each of the sensors to the computer 50. FIG. 1 also shows the signals from the computer 50 coupling by way of lines 54 to the respective valves 18. Finally, FIG. 1 shows the connection of the scale weights at lines 56 coupling from each of the scales 24 to the computer 50. Much of the control associated with the computer 50 has previously been discussed in connection with the operation in FIGS. 4-7. In accordance with the demand priority system, the ink weighing system places the requests from each fountain in a queue and enable each fountain in return to receive ink until the fountain level controller of that fountain is satisfied and the ink flow is shut off then at the fountain. This works well in all normal conditions. However, a failure of a fountain controller that causes it to call for ink continuously, a line breakage that would cause the ink to be discharged in some place other than the fountain, or a line blockage that prevents ink delivery, cause the system to hang up at that fountain and prevent further servicing of other fountains. To avoid this condition, a limit is placed on the length of delivery to any fountain. In this regard, refer to FIG. 8 which shows the level control coupling to some type of a gate 60 having a timer 62 associated therewith which represents the limit on time that pumping can occur to a fountain. When a fountain is enabled to receive ink and the fountain controller continues to call for delivery of ink for more than the preset time of timer 62, then service to that fountain is discontinued and the next fountain in the queue is enabled. The unsatisfied fountain is put back at the end of the queue. If the condition of remaining unsatisfied persists for a preset number of enablings, then a fault alarm is given to indicate that some form of fountain malfunction has occurred. In this regard, note the alarm output in FIG. 7. To ensure that the system is in a state of static equilibrium at the start and end of each measurement, a period of time is allowed to elapse from the shut-off of one fountain as indicated by the switching of the fountain demand signal to the OFF state and the enabling of the next fountain in the queue. During the period in which no ink is delivered, the ink pump is stationary and the pressure in the entire ink system from the pump to the respective fountain level controller solenoid valves is equal to the stall pressure of the pump. However, when a fountain valve is open, allowing ink to flow, the pump may stoke quite rapidly, delivering a reduced pressure at that time and the pressure in the downstream part of the system may be further reduced as a consequence of pressure drops in the lines. These changes in pressure in the system result in changes in the volume of the ink stored in the system as a result of the compressibility of ink and lines and also as a result of the compression of any air bubbles in the system. By ensuring that the system is always at the same state at the time of measurement, errors which might arise from these pressure changes in the system are avoided. The system also requires that a series of successive scale readings fall within the established tolerance band to ensure an accurate weight reading, before enabling the next fountain. By use of a pump stroke position sensor on each ink pump, the volume of ink delivered in a given period can be compared with the weight of ink delivered as measured by the scales. To give an incremental weight delivery for each stroke or fractional stroke of the ink pump, this pump calibration is carried out over a relatively large number of pump strokes, such as 1,000. The delivery to any one fountain will generally be a small number, in the range of ten to twenty strokes. However, the incremental weight delivered to the fountain may be precisely determined by counting the number of strokes and fractional strokes. Thus, one can arrive at an indication of weight per pump stroke. This in combination with the enabling of one fountain at a time makes it possible to thus quite accurately obtain an indication of weight of ink pumped, not only from an individual tank, but to each individual fountain. The use of the pumps and the fountain levelers are very convenient for many applications. In one extreme the pumps or the levelers would not be easy to interface. For this configuration, one can use very simple flow meters in the individual ink lines to determine when and how much volume is used by that line. This has the further virtue that many lines can use ink simultaneously from a common tank. The ink consumption is determined in either case as described below. The total ink consumption at any fountain is determined in several steps. As the ink supply system delivers ink to the fountains, the ink monitoring system totalizes the number of pump strokes and fractional strokes (that is: the volume used) during which ink is delivered to each fountain. These totals, multiplied by the last estimated pump constant in pounds per stroke (that is: density) give the estimated total ink weight consumption for each ink consuming point. ##EQU1## Because of changes in pump calibration, ink density, and other factors, the total ink consumption as measured by pump strokes (volume) differs from the total weight loss from the ink tank as measured by the scale. When the system is operated long enough, so that the uncertainty of weight measurement is a small fractional percentage of the total ink weight pumped, then a reconciliation is performed by determining the difference between pump stroke summation weight estimate and weight lost from the tank, and the difference is distributed proportionately among the ink consumption estimates. ##EQU2## Thus, while the system accuracy may be relatively low over short periods of operation, it becomes more and more accurate as operation continues. Such reconciliations are typically performed after just enough weight lost to ensure accuracy (typically 100 lbs.), or at transition points in the production operation, such as change of ink tank, change of the job being run on the press, or end of day or week. This is necessary in order that the production records prepared in those transitions be as accurate as possible. Reference is now made to FIG. 3 which shows a block diagram of the electronics of the ink monitor system of the present invention. In FIG. 3 there is illustrated the pump 12 and associated sensor 13. The pump and sensor couple to a pump sensor interface 65 and the output from the interface 65 couples to an analog-to-digital converter and multiplexer 66. The sensor output also illustrated in FIG. 1 coupling to the computer 50 is now more specifically defined in FIG. 3 as coupling to an analog-to-digital converter and multiplexer 66. The circuit 66 keeps track of the volume flow through the sensor 13 in terms of pump strokes. FIG. 3 also illustrates a scale 24, the output of which couples by way of an analog amplifier 68 to the scale power supply 69. The output of the power supply couples to a scale interface board 70 and the output from circuit 70 couples to a termination board 72. It is noted that the circuit 72 couples to a Z80 CPU counter timer 73, and also timer circuit 74 and 75. Furthermore, there are outputs from the circuit 72 coupled to the input of the I/O circuit 76. Reference is also now made to the aforementioned FIG. 5 and the block diagram set forth therein. Much of the circuitry shown in FIG. 3 relates to the block diagram of FIG. 5. The outputs from the scale are detected in terms of readings that are taken and interpreted in accordance with the previous teachings of FIG. 5. The circuitry described in FIG. 3 provides the aforementioned registration of successive weight outputs for comparison purposes to identify stability or instability at the scale. Inputs to the I/O circuit 76 indicate data being stored in computer memory for the purpose of comparisons. FIG. 3 also illustrates certain modem connections to the circuitry. These connect at the UART 77 and 78. These modem units permit communication externally with the system. In FIG. 3 reference is also made to the electronic interface relative to the ink levelers identified in FIG. 3 as ink levelers 79 and 80. These ink levelers provide the combined function of detection of liquid level (see also the sensor 45 in FIG. 4) as well as the capability of a liquid feed as controlled and illustrated previously in connection with the valve 18 shown in FIG. 4. In this connection it is noted that there is also provided in the circuitry, a second I/O circuit 82 having outputs that couple to a watchdog circuit 83. The circuit 83 may be of conventional design and simply receives periodic signals requesting a watch on the ink levelers. It is noted that the output of the watchdog circuit 83 couples to circuits 84 and 85. Circuits 84 and 85 may be data latch or register that is interrogated from the watchdog circuit to determine if any ink leveler is requesting ink flow. It is noted that the circuits 84 and 85 couple, respectively, to related circuits 86 and 87. These circuits may also be a form of latch or register and the outputs thereof couple to the input of the I/O circuit 82. Thus, as liquid level sensors detect a need for liquid flow, the signal is coupled by the respective storage registers to the computer via the circuit 82 to indicate the need for solenoid control. The solenoid control may also be carried out through an output from the I/O circuitry coupling to operate the respective solenoid valves. In this regard, note the control lines 54 coupled from the computer 50 in FIG. 1. As explained previously, one of the features of the system of the present invention is the advantage of being able to measure, not only total ink consumption from a storage tank, but also ink consumption to the individual consuming points or fountains. Again, in accordance with the invention, this is carried out by virtue of the aforementioned technique of enabling only one fountain at a time. There have been described previously, two different methods for carrying this out, one by time slot allocation and the other by demand priority queue. Now, in this regard, reference may be made to FIG. 9 which shows a series of cumulative counters. Each of these counters is enabled on a selective basis so that they count volume by virtue of pump strokes, but only during the time that the associated fountain is being filled. Therefore, the cumulative counter Fl in FIG. 9 is adapted to provide a count relating to volume detection, but only in the instance in which its associated fountain is receiving the ink. Thus, the output from this cumulative counter provides a total consumption associated with fountain number 1. FIG. 9 also shows by illustration, two other cumulative counters with their associated outputs. Thus, it can be seen from FIG. 9 that what is finally generated, is a series of cumulative counts each providing an indication of total ink weight consumption associated with that fountain. Having now described a limited number of embodiments of the present invention, it should now be apparent to those skilled in the art that numerous other embodiments and modifications thereof are contemplated as falling within the scope of the present invention as defined by the appended claims.	A system for monitoring ink flow from an ink storage tank to at least one ink fountain of a high-speed, web-fed printing press employing a scale for measuring the weight of the ink storage tank and comparing weight signals from the scale at successive times to determine the weight of ink consumed over the interval between readings. A pump is associated with the storage tank for pumping the ink to the fountain via coupling lines. An ink level sensor detects the level of ink in the fountain and provides an ink demand signal for operating a valve means in the ink coupling line to in turn cause ink flow to the fountain so as to provide replenishment of ink thereat. With the use of plural fountains, means are provided for prioritizing delivery to the fountains so that individual ink consumption on a per fountain basis can be determined. In this regard, the system also employs a volume sensor preferably in the form of a pump stroke position sensor for determining incremental weight delivery per stroke.	1
RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60/466,844, filed Apr. 29, 2003. FIELD OF THE INVENTION [0002] The invention relates to methods for preparing as-deposited, low-stress and low resistivity polycrystalline silicon-germanium layers and semiconductor devices utilizing the silicon-germanium layers. These layers can be used in Micro Electro-Mechanical Systems (MEMS) devices or micro-machined structures. BACKGROUND OF THE INVENTION [0003] Micro Electro-Mechanical Systems (MEMS) are used in a wide variety of systems such as accelerometers, gyroscopes, infrared detectors, micro turbines, and the like. For high volume applications, fabrication costs can potentially be reduced by monolithic integration of MEMS with the driving electronics. For 2D imaging applications, such as detectors and displays, monolithic integration of MEMS and CMOS processing is a desirable solution as this simplifies the interconnection issues. The easiest approach for monolithic integration is post-processing MEMS on top of the driving electronics, as this does not introduce any change in the standard fabrication processes used for preparing the driving electronics. It also allows the preparation of a more compact micro-system. This is not possible if the MEMS device is produced prior to the formation of the driving electronics. On the other hand, post processing imposes an upper limit on the fabrication temperature of MEMS to avoid any damage or degradation in the performance of the driving electronics. This upper limit on temperature is typically 450° C. An overview of several approaches for the integration of driving electronics and MEMS devices can be found in ‘Why CMOS-integrated transducers? A review’, Microsystem Technologies, Vol. 6 (5), p 192-199, 2000, by A. Witvrouw et al. [0004] For many micromachined devices, such as transducers and other freestanding structures, the mechanical properties of the applied thin films can be critical to their success. For example, stress or stress gradients can cause freestanding thin-film structures to warp to the point that these structures become useless. Such thin film layers ideally have a low stress and a zero stress gradient. If the stress is compressive (indicated by a minus sign (−)), structures can buckle. If the tensile stress is too high (indicated by a plus sign (+)), structures can break. If the stress gradient is different from zero, microstructures can deform, for example, cantilevers can bow. [0005] Polycrystalline silicon (poly Si) has been widely used for MEMS applications. The main disadvantage of this material is that it requires high processing temperatures, namely, higher than 800° C., to achieve the desired physical properties, especially properties related to stress, as explained in “Strain studies in LPCVD polysilicon for surface micromachined devices,” Sensors and Actuators A (physical), A77 (2), p. 133-8 (1999), by J. Singh et al. Accordingly, poly Si MEMS applications can not be used for integration with CMOS if the CMOS is processed before the MEMS device. [0006] Polycrystalline silicon germanium (poly SiGe) is known in the art as an alternative to poly Si as it has similar properties. The presence of germanium reduces the melting point of the silicon germanium alloy, and hence the desired physical properties can be achieved at lower temperatures, allowing the growth on low-cost substrates such as glass. Depending on the germanium concentration and the deposition pressure, the transition temperature from amorphous to polycrystalline can be reduced to 450° C., or even lower, compared to 580° C. for CVD poly Si. [0007] A functional poly SiGe layer for use in microstructure devices, such as gyroscopes, accelerometers, micro-mirrors, resonators, and the like, which are typically from about 3 μm to about 12 μm thick, requires low-stress (<20 MPa compressive and <100 MPa tensile) and low electrical resistivity. An important factor for industrial applicability is that it is possible to produce these layers at a relatively high deposition rate. A reasonably small variance of characteristics between different points on the wafer is preferably also achieved. [0008] U.S. Appl. No. 10/263,623, filed Oct. 3, 2003, now U.S. Pub. No. 2003-0124761-A1, the contents of which are hereby incorporated by reference in their entirety, deals with the development of low-stress poly-SiGe layers under different deposition parameters. Some deposition parameters studied include, for example, the deposition temperature, the concentration of semiconductors (e.g., the concentration of silicon and germanium in a Si x Ge 1-x layer, with x being the concentration parameter), the concentration of dopants (e.g., the concentration of boron or phosphorous), the amount of pressure, and the use of plasma. [0009] Fast deposition methods such as PACVD (Plasma Assisted Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition) having a typical deposition rate greater than about 100 nm/min typically yield amorphous layers with high stress and high resistivity at temperatures compatible with CMOS (450° C. or lower), at low germanium concentrations. Polycrystalline layers deposited with PECVD with low stress and low resistivity are described in WO01/74708, but are deposited only at high temperatures (above 550° C.). [0010] Slow deposition methods such as CVD, with typical deposition rates of from about 5 to about 15 nm/min, can yield crystalline layers with a low resistivity at 450° C., but this is generally not an economical process in a single wafer tool for, e.g., 10 μm thick layers, since the processing time is long. In WO01/74708 it is indicated that the CVD deposition of in situ boron doped polycrystalline SiGe at lower temperature (about 400° C.) is feasible if the Ge concentration is sufficiently high (above 70%) and if the boron concentration is sufficiently high (above 10 19 /cm 3 ). SUMMARY OF THE INVENTION [0011] A deposition process for preparing polycrystalline-SiGe layers and devices while preferably improving stress and/or resistivity and/or speed of deposition is desirable. [0012] Accordingly, in a first embodiment a method of producing a polycrystalline SiGe layer on a substrate is provided, the method including depositing onto the substrate a first layer including polycrystalline silicon-germanium, wherein the depositing includes non-plasma chemical vapor deposition conducted at a first temperature less than or equal to about 520° C.; and depositing onto the first layer a second layer including polycrystalline silicon-germanium, wherein the depositing includes plasma enhanced chemical vapor deposition or plasma assisted chemical vapor deposition at a second temperature less than or equal to about 520° C., whereby a polycrystalline SiGe layer including the first layer and the second layer is obtained. [0013] In an aspect of the first embodiment, the method further includes depositing a nucleation layer onto the substrate at a third temperature less than or equal to about 520° C., wherein the depositing is conducted before depositing the first layer. [0014] In an aspect of the first embodiment, the nucleation layer includes silicon or Si x Ge 1-x wherein 0.10≦x. [0015] In an aspect of the first embodiment, the first layer includes Si y Ge 1-y wherein 0.10≦y≦1. [0016] In an aspect of the first embodiment, the first layer includes Si y Ge 1-y wherein 0.50≦1-y≦0.70. [0017] In an aspect of the first embodiment, the second layer includes Si z Ge 1-z wherein 0.10≦z≦1. [0018] In an aspect of the first embodiment, the second layer includes Si z Ge 1-z wherein 0.50≦1-z≦0.70. [0019] In an aspect of the first embodiment, the first temperature, the second temperature, and the third temperature are each less than or equal to about 500° C. [0020] In an aspect of the first embodiment, the first temperature, the second temperature, and the third temperature are each less than or equal to about 450° C. [0021] In an aspect of the first embodiment, the first temperature equals the second temperature, and the second temperature equals the third temperature. [0022] In an aspect of the first embodiment, the first temperature equals the second temperature, the second temperature equals the third temperature, and the third temperature equals about 450° C. [0023] In an aspect of the first embodiment, the second layer includes Si z Ge 1-z wherein 0.50≦1-z≦0.70. [0024] In an aspect of the first embodiment, the second layer includes Si z Ge 1-z wherein 0.60≦1-z≦0.70. [0025] In an aspect of the first embodiment, the steps of depositing the first layer and the second layer are performed at a pressure of from about 1 to about 10 Torr. [0026] In an aspect of the first embodiment, a plasma power is from about 10 to about 100 W. [0027] In an aspect of the first embodiment, a plasma power density is from about 20 to about 200 mW/cm 2 . [0028] In an aspect of the first embodiment, the polycrystalline SiGe layer has an electrical resistance of less than about 10 mΩcm. [0029] In an aspect of the first embodiment, the polycrystalline SiGe layer has a compressive stress of less than about 20 MPa and a tensile stress of less than about 100 MPa. [0030] In a second embodiment, a method of producing a SiGe layer on a substrate is provided, the method including depositing onto the substrate a first layer including a polycrystalline silicon-germanium by a non-plasma chemical vapor deposition technique at a temperature of less than or equal to 520° C. and at a rate of less than about 10 nm/min; and depositing onto the first layer a second layer including polycrystalline silicon-germanium by a plasma enhanced chemical vapor deposition technique at a temperature of less than or equal to 520° C. and at a rate of about 50 nm/min or more, whereby a polycrystalline SiGe layer including the first layer and the second layer is obtained. [0031] In an aspect of the second embodiment, the step of depositing the second layer is conducted at a rate of about 100 nm/min or more. BRIEF DESCRIPTION OF THE DRAWINGS [0032] FIG. 1 shows sensor locations, indicated by numbered positions, on a stressmeter for a 6 inch wafer. [0033] FIG. 2 shows a poly SiGe layer stack in accordance with a preferred embodiment. [0034] FIG. 3 shows variation of average stress with deposition temperature for a poly SiGe layer. [0035] FIG. 4 shows variation of average resistivity with deposition temperature for a poly SiGe layer. [0036] FIG. 5 shows variation of average resistivity with silane flow rate for a poly SiGe layer. [0037] FIG. 6 shows variation of average stress with silane flow rate for a poly SiGe layer. [0038] FIG. 7 includes Scanning Electron Microscope (SEM) images of a MEMS cantilever constructed in a SiGe layer in accordance with a preferred embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0039] The following description and examples illustrate a preferred embodiment of the present invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a preferred embodiment should not be deemed to limit the scope of the present invention. [0040] A polycrystalline SiGe (poly SiGe) layer is deposited on top of a substrate, e.g., a substrate comprising a semiconductor material, at a temperature compatible with the underlying material, e.g., at least one semiconductor device made by CMOS processing. In preferred embodiments, the term “substrate” as used herein, is a broad term and is used in its ordinary sense, including, without limitation, to describe any underlying material or materials that can be used, or can contain, or upon which a device such as a MEMS device, a mechanical, electronic, electrical, pneumatic, fluidic or semiconductor component or similar, a circuit or an epitaxial layer can be formed. In various embodiments, the “substrate” can include a semiconductor substrate such as, for example, a doped silicon substrate, a gallium arsenide (GaAs) substrate, a gallium arsenide phosphide (GaAsP) substrate, an indium phosphide (InP) substrate, a germanium (Ge) substrate, or a silicon germanium (SiGe) substrate. The “substrate” can include, for example, an insulating layer such as a SiO 2 or a Si 3 N 4 layer in addition to a semiconductor substrate portion. Thus, the term “substrate” also encompasses substrates such as silicon-on-glass and silicon-on sapphire substrates. The term “substrate” is thus used to define generally the elements for layers that underlie a layer or portions of interest. The “substrate” can be any base on which a layer is formed, for example, a glass substrate or a glass or metal layer. As discussed herein, processing is primarily described with reference to processing silicon substrates, but the skilled person will appreciate that the preferred embodiments can be implemented based on other semiconductor material systems, and that the skilled person can select suitable materials as equivalents, as for example, glass substrates. [0041] The thickness of the SiGe layer is preferably from about 0.5 μm or less to about 25 μm or more, preferably from about 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, .2.9, 3, 3.5 4, 4.5, 5, 5.5, 6, 6.5, or 7 μm to about 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 μm, and more preferably from about 8, 8.5, 9, 9.5 or 10 μm to about 11, 11.5, or 12 μm. It is preferred to maintain a low or controlled stress or a low or controlled stress gradient and a low or controlled resistivity in the deposited SiGe films. In accordance with a preferred embodiment, a polycrystalline SiGe layer is deposited by a combination of Plasma Enhanced Chemical Vapor Deposition (PECVD) or Plasma Assisted Chemical Vapor Deposition (PACVD) and Chemical Vapor Deposition (CVD) processes. The CVD process can be a low pressure up to atmospheric pressure CVD process. The CVD process can be a batch or single wafer process. Preferably, the CVD process is a non-plasma CVD process [0042] The PECVD or PACVD poly SiGe layers are deposited in a suitable deposition system, such as a batch or single wafer system. An example of a suitable system is an Oxford Plasma Technology (OPT) Plasma Lab 100 cold wall system. This system consists of two chambers and a central loadlock system. A SiC-covered graphite plate can be used as a carrier for a substrate or semiconductor wafer to avoid contamination at high temperature. The substrate rests on the chuck, which is the bottom electrode. The reaction gases are fed into the chamber from the top through the top electrode with an integrated shower head gas inlet. A graphite heater heats the chuck to the desired temperature. The calibration for actual wafer temperature can be done in vacuum and at a hydrogen pressure of 2 Torr with a thermocouple wafer, having a number of, e.g. seven, thermocouples. This system provides the advantage that one system can be used for both low pressure CVD and PECVD. The preferred embodiments are not limited to the use of a single system and include use of systems and devices dedicated to one or more of these processing techniques. [0043] For SiGe depositions, the gas flows are preferably fixed at a suitable rate, e.g., 166 sccm 10% GeH 4 in H 2 and 40 sccm 1% B 2 H 6 in H 2 . The SiH 4 flow rate is preferably varied and the chamber pressure is preferably maintained at a suitable pressure, such as 2 Torr. Films are preferably deposited on (100) Silicon wafers covered with an oxide layer, preferably a thermal oxide layer, e.g., a 250 nm thick thermal oxide. In preferred embodiments, a plasma power of from 10W or less to about 100W or more can be used for the PECVD deposition, preferably from about 10, 15, 20, or 25W to about 40, 50, 60, 70, 80, or 90W, more preferably about 30W. For an electrode diameter of about 25 cm, the plasma power density equals about 60 mW/cm 2 . The plasma power density range is preferably from about 20 mW/cm 2 or less to about 200 mW/cm 2 or more, preferably from about 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 mW/cm 2 to about 110, 120, 130, 140, 150, 160, 170, 180, or 190 mW/cm 2 . Preferably no plasma power is used for the pure low pressure to atmospheric pressure CVD deposition. The CVD deposition is optionally done on top of a nucleation layer. The nucleation layer is preferably an amorphous seed layer, e.g., a PECVD deposited seed layer, preferably a PECVD deposited amorphous seed layer. Such layers can be employed to avoid large incubation times. A seed layer is not necessarily preferred when a time budget is not an issue. The incubation time can constitute a certain delay in the SiGe layer production. See, e.g., Lin et al., entitled ‘Effects of SiH 4 , GeH 4 and B 2 H 6 on the Nucleation and Deposition of Polycrystalline Si 1-x GE x Films’, J. Electrochem. Soc., Vol. 141, No. 9, September 1994, pp 2559-2563, which discloses values of incubation times at 550° C. and pressures of 0.94-1.95 mTorr, namely, 36 minutes for undoped poly-Si, 51 minutes for undoped poly-SiGe, 3 minutes for B-doped poly-Si, and 2 minutes for B-doped poly-SiGe. [0044] In King et al., ‘Deposition and Properties of Low-Pressure Chemical-Vapor Deposited Polycrystalline Silicon-Germanium Films’, J. Electrochem. Soc., Vol. 141 (8), August 1994, pp 2235-2240, it is disclosed that the incubation time rises with decreasing temperature. [0045] The stress of the SiGe film can be measured using a suitable device, such as an Eichorn and Hausmann MX 203 stressmeter, as depicted schematically in FIG. 1 . Sensor locations are indicated by numbered positions. The stressmeter gives the average stress of the film by measuring the bow of the wafer before and after the deposition. The stressmeter has 2×33 sensors, from which 16 local stress values can be measured. For the center stress (Ct), measurements are made on triplets consisting of a center point and two points on the diametrically opposite edges. There are four such triplets on a 6 inch wafer (16-1-21, 24-1-33, 6-1-11, 27-1-30). An average of these values gives the center stress. For the average (Av) stress calculation, triplets are composed of three immediate neighboring points on a radial line. An average of all such triplets is taken to determine the average stress value. [0046] The sheet resistance can be measured over the wafer using a suitable probe, e.g., a four-point probe. Rutherford Backscattering (RBS) measurements can be carried out to measure Si and Ge concentrations in the film. [0047] Any deposited SiGe layer in accordance with the preferred embodiments can be processed by any conventional semiconductor or MEMS processing method. For example, photolithography can be carried out to pattern the as-deposited SiGe layers. For example, the SiGe layer can be etched, e.g., in a Surface Technology Systems plc (STS) deep dry etching system, which uses an SF 6 +O 2 /C 4 F 8 alternating plasma. [0048] Film thickness can be measured using a Dektak surface profiler. Any underlying sacrificial SiO 2 can be removed by a vapor HF etch. The results of different conventional methods are described below, followed by the results of a method according to a preferred embodiment. [0049] In a preferred embodiment, a combination of CVD and PECVD or PACVD processes can be used to obtain polycrystalline films at a low temperature compatible with, e.g., CMOS processes. FIG. 2 depicts schematically (not to scale) the resulting layers. A nucleation layer A (e.g., a thin PECVD or PACVD layer approximately 94 nm in thickness) is deposited in order to avoid a large incubation time for the growth of SiGe on SiO 2 . Nucleation layer B preferably has a thickness of 5 nm or less to about 200 nm or more, more preferably from about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 nm to about 110, 120, 130, 140, 150, 160, 170, 180, or 190 nm. The nucleation layer A is believed to be amorphous and acts as a seed layer for the CVD layer B. CVD layer B is deposited on the nucleation layer A. CVD layer B preferably has a thickness of 5 nm or less to about 400 nm or more, more preferably from about 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, or 350 nm to about 360, 370, 380, or 390 rm. The CVD layer B can also act as a crystallization seed layer for a PECVD or PACVD layer C, thus making it possible to obtain a polycrystalline film at low temperatures. The thickness of PECVD or PACVD layer C is preferably from about 50 nm or less to about 700 nm or more, more preferably from about 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390 nm, or 400 nm to about 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, or 675 nm. For example, a layer A of thickness of about 94 nm, a layer B of thickness of about 370 nm, and a layer C of thickness of about 536 nm yields a total thickness of about 1 μm. deposited on top of the CVD layer B, thus making it possible to obtain a polycrystalline film at low temperatures. To reduce processing temperatures it is preferred if the percentage of germanium in the SiGe CVD layer is 10% or more. In preferred embodiments, the percentage of germanium in the the poly SiGe layers is an independently selected value of from about 5% or more, preferably from about 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% to about 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95%, or more. Preferably, the deposition process is conducted at a temperature of about 520° C. or less, more preferably at a temperature of about 515, 510, 505, 500, 495, 490, 485, 480, 475, 470, 465, 460, 455, or 450° C. or less. It is generally preferred that the deposition process is conducted at a temperature of about 300° C. or higher, preferably higher than 305, 310, 315, 320, 325, 330, 335, 340, 345, 350 or higher, more preferably 355, 360, 365, 370, 375, 380, 385, 390, 395, 400, 405, 410, 415, 420, 425, 430, 435, 440, or 445° C. or higher. The growth speed at a temperature of 400° C. is about 4 nm/min. At temperatures lower than 300° C., insufficient growth speeds can be observed, however, in certain embodiments lower temperatures can be acceptable. [0050] Various nucleation layers can be employed, e.g., undoped SiGe, doped silicon (preferably B-doped), or undoped silicon. Each of the layers (nucleation layer, CVD layer, and PECVD or PACVD layer) can independently be optionally doped with the same or different doping or dopants, or can be undoped. Each layer can have a different doping concentration. Comparative Example 1—PECVD or PACVD at 520° C. [0051] A first series of films were deposited at 520° C. Deposition conditions and properties of the films are provided in Table 1. PECVD was used to take advantage of the higher growth rates. At 520° C., growth rates up to 140 nm/min were observed. These films had very low resistivity values (0.6-1.0 mΩcm) and were expected to be polycrystalline. TABLE 1 Measurement Results for PECVD Films Deposited at 520° C. Wafer temp. SiH 4 flow Power T deposit Stress Thick Rsheet sq ρ Ge conc. [° C.] [sccm] [W] [min] [MPa] [μm] [Ω] [mΩcm] [%] 520 30 30 10 Ct = +13 1.0-1.3 4.4-6.6 0.6-0.7 60 Av = +9 520 50 30 10 Ct = −8 1.1-1.5 4.4-6.6 0.6-0.8 53 Av = −12 520 70 30 10 Ct = −26 1.3-1.5 4.2-7.4 0.6-1.0 45 Av = −37 [0052] It is noted that this temperature can be too high for some processes. For CMOS compatibility, lower temperatures (e.g. at 450° C. or lower) are recommended. Comparative Example 2—PECVD 450° C. [0053] Boron and phosphorous doped PECVD SiGe films were deposited at 450° C. For the P-doped films, unacceptably high resistivity values (>10 5 mΩcm) were obtained. Similarly, for B-doped films, a very high compressive stress and large resistivity values were obtained, indicating that the films were not polycrystalline but amorphous in nature. Comparative Example 3—CVD 450° C. [0054] CVD films deposited at 450° C. had low resistivity values. Deposition conditions and properties of the films are provided in Table 2. The long deposition times make the process unsuitable for use in preparing thick films. TABLE 2 Measurement Results for CVD Films Deposited at 450° C. Using an Undoped PECVD Amorphous Si Nucleation Layer Wafer temp. SiH 4 flow Power T deposit Stress Thick Rsheet sq ρ Ge conc. [° C.] [sccm] [W] [minutes] [MPa] [μm] [Ω] [mΩcm] [%] 450 30 0 120 Ct = −28 1.9-2.5 2.7-2.8 0.6 64 Av = −31 450 50 0 120 Ct = −103 2.1-2.4 3.0-3.5 0.7 55 Av = −105 450 70 0 120 Ct = −167 1.8-2.0 3.0-4.0 0.6-0.7 47 Av = −160 Example 4—CVD+PECVD Films at 450° C. [0055] Different variations of the process of preferred embodiments were investigated by varying the silane flow rates and deposition temperatures. A poly SiGe deposition was conducted as follows. A 5 min H 2 anneal is followed by a brief PECVD deposition at the specified plasma power to form a nucleation layer. The plasma power density range was about 60 mW/cm 2 (electrode diameter of approximately 25 cm). The gas flows were fixed at the following rates: 166 sccm 10% GeH 4 in H 2 , 40 sccm 1% B 2 H 6 in H 2 . SiH 4 flow rate was varied and the chamber pressure was maintained at 2 Torr. Next, a 20 minute CVD step was conducted to deposit a CVD layer of about 370 nm in thickness. Finally, a PECVD processing step at the specified plasma power was carried out to deposit a PECVD layer of sufficient thickness to obtain the specified overall thickness of the poly SiGe layer. The deposition rate for this step was approximately 113 nm/min. The nucleation layer was B-doped SiGe. [0056] The method for forming the poly-SiGe layer was performed at, respectively, 420, 435 and 450° C. The data demonstrate that for deposition at 450° C. a low stress, low resistivity layer is obtained at a reasonable deposition rate (39 nm/min for a total thickness of about 1 μm. Such a layer cannot be obtained by the use of PECVD alone. The overall or total deposition rate increases even more for thicker films, wherein the following fraction increases as follows: deposition ⁢ ⁢ time PECVD total ⁢ ⁢ deposition ⁢ ⁢ time [0057] As can be seen in the data of Table 3, the films were more compressive and the resistivity values higher when the deposition temperature was decreased below 450° C. (see FIG. 3 , which shows variation of average stress with deposition temperature for a poly SiGe layer, and FIG. 4 , which shows variation of average resistivity with deposition temperature). While not wishing to be bound by any particular theory, it is believed that lowering the temperature reduces the crystallinity of the films, which is in accordance with the above observations. TABLE 3 CVD + PECVD SiGe Films at Different Deposition Temperatures Deposition time T wafer SiH 4 Power [‘ = minutes Thickness Stress R sheetsq ρ Ge conc. [° C.] [sccm] [W] “ = seconds] [μm] [MPa] [ohm] [mΩcm] [%] ˜420 30 (30+) 50″ PECVD 0.9-1.0 Ct = −72 14-45 1.4-4.0 66 0 + 30 nucleation+ 20′CVD + 6′ Av = −79 PECVD ˜435 30 (30+) 50″ PECVD 0.8-1.0 Ct = −50 13-47 1.3-3.8 66 0 + 30 nucleation+ 20′CVD + 5′30″ Av = −59 PECVD ˜450 30 (30+) 50″ PECVD 0.9-1.1 Ct = −0.6 7-13 0.8-1.2 65 0 + 30 nucleation+ 20′CVD + 5′ Av = −5 PECVD [0058] The method for forming a poly SiGe layer was also performed for different silane flow rates (30, 40 and 50 sccm, respectively) at a deposition temperature of 450° C. Data for the resulting layers is provided in Table 4. As the GeH 4 /SiH 4 ratio increased, the Ge concentration in the film also increased. The RBS data shows a sharp fall in the germanium concentration with the increase in silane concentration. An increase in Ge concentration reduced the amorphous to crystalline transition temperature, thus it is believed that this increase resulted in more crystalline films at lower temperatures. It is expected that more crystalline films have lower resistivity values. This can be clearly observed in FIG. 5 , which provides data regarding variation of average resistivity with silane flow rate. Also, the compressive stresses in films increases as the silane flow increases, as shown in FIG. 6 , which shows variation of average stress with silane flow rate. TABLE 4 CVD + PECVD Films at Silane Flow Rates of 30, 40 and 50 sccm Deposition time Ge T wafer SiH 4 Power [‘ = min Thickness Stress R sheetsq ρ conc. [° C.] [sccm] [W] “ = seconds] [μm] [MPa] [ohm] [mΩcm] [%] ˜450 30 (30+) 0 + 30 50″ PECVD 0.9-1.1 Ct = −0.6 7-13 0.8-1.2 65 nucleation+ 20′ Av = −5 CVD + 5′ PECVD ˜450 40 (30+) 0 + 30 50″ PECVD 0.9-1.1 Ct = −43 9-15 1.0-1.4 60 nucleation+ 20′ Av = −52 CVD + 4′48″ PECVD ˜450 50 (30+) 0 + 30 50″ PECVD 0.9-1.1 Ct = −78 11-28 1.2-2.5 56 nucleation+ 20′ Av = −83 CVD + 4′36″ PECVD [0059] A 1 μm poly SiGe film (450° C.) was deposited as follows. A 5 minute H 2 anneal was conducted to ensure temperature uniformity across the wafer. 50 seconds PECVD flash yielding a thin nucleation SiGe layer of approximately 94 nm thickness, 20 minutes CVD step at 2 Torr with 30 sccm SiH4, 166 sccm 10% GeH 4 in H 2 and 40 sccm 1% B 2 H 6 in H 2 to form a CVD layer of approximately 370 nm thickness. 5 minutes PECVD with the same gas flows and pressure, and 30 W plasma power to form a PECVD layer. The film thus prepared exhibited an average compressive stress of −5 MPa and an average resistivity value of 1.0 mΩcm. The RBS data showed a germanium concentration of 65% in the PECVD layer. [0060] Table 5 illustrates the relationship between the overall or total deposition time and the fraction: deposition ⁢ ⁢ time PECVD total ⁢ ⁢ deposition ⁢ ⁢ time wherein: total deposition time=deposition time nucleation PECVD +deposition time CVD +deposition time PECVD The deposition time nucleation PECVD and the deposition time CVD were fixed at 50 seconds and 20 minutes, respectively. The resulting overall deposition rate increased for thicker films, with the following fraction increasing: deposition ⁢ ⁢ time PECVD total ⁢ ⁢ deposition ⁢ ⁢ time [0063] The deposition process marked with an asterisk () in Table 5 was performed with a PECVD deposited amorphous silicon layer instead of a PECVD SiGe layer. All films had a low resistivity and a low stress, and were suitable for surface micromachining. TABLE 5 PECVD deposition Total deposition time time Deposition [‘ = min [‘ = min Thickness Stress ρ Ge conc. rate “ = seconds] “ = seconds] [μm] [MPa] [mΩ-cm] [%] [nm/min] 5′ 25′ 50″ 0.9-1.1 Ct = −0.6 0.8-1.2 65 39 Av = −5 10′ () 30′ 50″ 1.5-1.7 Av = +20 0.9-1 Not 53 measured 84′ 24″ 105′ 14″ 10-13 Av = +71 0.9 64 109 [0064] In Table 6, data is presented illustrating the superior properties of poly SiGe layers prepared according to the preferred embodiments. TABLE 6 Comparison Between Conventional Methods (Power = 0, 30) and Method of Preferred Embodiment (Power = 0 + 30) T wafer SiH 4 Power Deposition time Stress Thickness ρ [° C.] [sccm] [W] [minutes] [MPa] [μm] [mΩcm] Crystalline? 450 30 0 (CVD) 120 Av = −31 1.9-2.5 0.6 Yes 450 30 30 (PECVD) 10 Av = −104 not >10e 4 No measured 450 30 0 + 30 20 + 10 Av = +20 1.5-1.7 0.9-1 Yes [0065] From the above results certain optimized operation conditions can be determined. For example, the optimum value for x is a function of Tn (the time for preparing the nucleation layer), the optimum value for y is a function of T1 (the time for preparing the CVD layer), and the optimum value for z is a function of T2 (the time for preparing the PECVD or PACVD layer). Preferably, Tn=T1=T2=T. Under such conditions, T is preferably about 450° C. and 0.50≦1-z≦0.70, more preferably 0.60≦1-z≦0.70. [0066] FIG. 7 shows free cantilevers formed in a SiGe layer deposited in accordance with a preferred embodiment. Such microstructures can be formed above layers comprising semiconductor active components, e.g., components as formed by CMOS processing. [0067] The above description discloses several methods and materials of the present invention. This invention is susceptible to modifications in the methods and materials, as well as alterations in the fabrication methods and equipment. Such modifications will become apparent to those skilled in the art from a consideration of this disclosure or practice of the invention disclosed herein. Consequently, it is not intended that this invention be limited to the specific embodiments disclosed herein, but that it cover all modifications and alternatives coming within the true scope and spirit of the invention as embodied in the attached claims. All patents, applications, and other references cited herein are hereby incorporated by reference in their entirety.	The invention relates to methods for preparing as-deposited, low-stress and low resistivity polycrystalline silicon-germanium layers and semiconductor devices utilizing the silicon-germanium layers. These layers can be used in Micro Electro-Mechanical Systems (MEMS) devices or micro-machined structures.	7
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a power supply with a performance display, and particularly relates to a power supply having a control module and a display to show a real time operating status. [0003] 2. Description of Related Art [0004] Most electronic products including computers require direct current for operation, and for the computer, a power converter is generally mounted to transform the external alternating currents to a direct current. As for other electronic products, they often have batteries or adapters to provide direct current. Normally, those power converters or adapters have specifications printed thereon; however, the actual operating characteristics and performance status are not clearly shown from the external appearance. In other words, it is not convenient for users to know the actual operating status especially when more loads are added, such as updating or increasing peripheral equipment. Thus, the safe operation of the devices cannot be definitely protected. [0005] Therefore, the invention provides a computer power supply with a performance display to mitigate or obviate the aforementioned problems. SUMMARY OF THE INVENTION [0006] The main objective of the present invention is to provide a computer power supply with a performance display that shows operating status of the power converter on a display, such as current signals, power signals, total operation time etc. [0007] The computer power supply with a performance display mainly has a power converter to transform external power supplies; a control module performing as an arithmetic and control unit, which is responsible for processing signals from the power converter and then sending those processes signals to a display; the display is an LCD or LED, whereby the operating status of the power converter is shown in a numerical value form. [0008] Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a perspective view of a first embodiment of a computer power supply with a performance display in accordance with this invention; [0010] FIG. 2 is a circuit block diagram of the first embodiment of the computer power supply with a performance display in accordance with this invention; [0011] FIG. 3 is an oscillogram showing a time sequence of the power supply of the power converter and the POWER GOOD signal; [0012] FIG. 4 is a circuit diagram of an alarm generator in accordance with this invention; [0013] FIG. 5 is a circuit diagram of a temperature sensing circuit in the power converter in accordance with this invention. [0014] FIG. 6 is a front view of a second embodiment of the power supply with a performance display in accordance with this invention; and [0015] FIG. 7 is a block diagram of a third embodiment of the power supply with a performance display in accordance with this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0016] With reference to FIG. 1 , a computer power supply with a performance display in a first embodiment has a power converter ( 10 ), a control module ( 20 ) and a display ( 30 ). The power converter is referred to a power supply ( 10 ) mounted in the computer chassis ( 100 ) to transform the external power into at least one direct current power that can be utilized by the computer. The control module ( 20 ), which can be fabricated in the form of a peripheral device, is equipped in the expansion slot ( 101 ) of the computer chassis ( 100 ), which processes various signals collected from the power supply ( 10 ), and then sends those processed signals to the display ( 30 ). The display ( 30 ) is mounted in the computer chassis ( 100 ) to show a real operation status of the power supply ( 10 ). The display ( 30 ) coupled to the control module ( 20 ) is generally an LCD (liquid crystal display) or an LED-based (Light Emitting Diode) display. [0017] The internal structure of the power supply ( 10 ) is of a conventional technique so detailed description is omitted. [0018] With reference to FIG. 2 , the control module ( 20 ) of the computer power supply has a microprocessor ( 21 ), which is an arithmetic and control unit. An analog to digital (A/D) converter ( 22 ) has multiple inputs to receive status signals such as current signals, power signals, temperature signals etc from the power supply ( 10 ). The A/D converter ( 22 ) further has an output connected to the microprocessor ( 21 ) through a first internal bus (not numbered). An external interrupt source ( 23 ), a real time clock ( 24 ) and a memory ( 25 ) are all connected to the microprocessor ( 21 ) through the first internal bus, wherein the microprocessor ( 21 ) gets a warning signal (referred to the POWER GOOD signal hereinafter) from the power supply ( 10 ) through the external interrupt source ( 23 ). The real time clock ( 24 ) counts the total operation time of the power supply ( 10 ). The memory ( 25 ) can be an EEPROM (Electrically Erasable Programmable Read Only Memory) or FLASH RAM, and used for storing data such as alarm setting values or total operation time. [0019] When the computer is working, the power supply ( 10 ) begins to provide direct current to related computer elements. The microprocessor ( 21 ) then gets the current signals, power signals and temperature signals through the A/D converter ( 22 ), and those signals are transformed into numerical value in the microprocessor ( 21 ) and then shown on the display ( 30 ) as reference information for a user who accordingly can handle the status of the power supply ( 10 ). [0020] The external interrupt source ( 23 ) in the control module ( 20 ) is responsible for picking the POWER GOOD signal from the power supply ( 10 ). Once the external power supply breaks down, or the switch is turned off, or the excessive voltage/current protection occurs, the POWER GOOD signal will have a status change. The status change of the POWER GOOD signal informs the microprocessor ( 21 ) via the external interrupt source ( 23 ) that the power supply ( 10 ) will soon stop providing power and the microprocessor ( 21 ) then chooses an appropriate time to store the data in the memory ( 25 ). There is a time space between the status change and the power stop moment as shown in FIG. 3 . With reference to FIG. 3 , the power status V33/V5/V12/IS33/IS5/IS12 of the power supply ( 10 ) is illustrated below the warning signal (PG). Prior to the descent of the power status signal, the warning signal (POWER GOOD, PG) has become a low level. Such a pre-warning function can be achieved by, for example, the WT7515 chip fabricated by Weltrend™ company. Therefore the control module ( 20 ) will get the status change of the POWER GOOD signal in advance, and the microprocessor ( 21 ) stores the related data including the total operation time counted by the real time clock ( 24 ) and the alarm setting value to the memory ( 25 ). [0021] Besides, the control module ( 20 ) further has a digital to analog (D/A) converter ( 26 ), a time/number counter ( 27 ), an alarm generator ( 28 ), a transmission interface ( 29 ) and a control interface ( 201 ). The D/A converter ( 26 ) connects to the microprocessor ( 21 ) through the first internal bus and sends a fan speed control signal to the power supply ( 10 ). The time/number counter ( 27 ) receives a signal representing the rotation speed (RPM) of a cooling fan of the power supply ( 10 ) and has an output connected to the microprocessor ( 21 ) through the first internal bus. The alarm generator ( 28 ) connected to the microprocessor ( 21 ) consists of a buzzer as shown in FIG. 4 . When the temperature is excessively high, the buzzer will sound to alert the user. The transmission interface ( 29 ) is connected to the microprocessor ( 21 ) through the first internal bus. The transmission interface ( 29 ) is a serial communication interface such as UART (Universal Asynchronous Receiver Transmission), USB (Universal Serial Bus), or I2C BUS, which performs the data transmission to the computer. The control interface ( 201 ) is connected to the microprocessor ( 21 ) through a second bus (not numbered). The control interface ( 20 ) can be in the form of an external press key set, where the user can control the fan rotation speed through the control interface ( 20 ). [0022] The bus between the microprocessor ( 21 ) and the display ( 30 ) can be a serial bus or a parallel bus performed by, for example, an LCD controller HT1611 manufactured by Holtek™ company. The serial bus mode requires fewer input/output pins (PIO) for the microprocessor ( 21 ), but the transmission is comparatively slow. The parallel bus mode uses more input/output pins for the microprocessor ( 21 ) and has a comparatively rapid transmission speed. Information about the output current, temperature, fan rotation speed and the total operation time are shown on the display ( 30 ). [0023] The D/A converter ( 26 ), the time/number counter ( 27 ), the alarm generator ( 28 ), the transmission interface ( 29 ) and the control interface ( 201 ) built in the control module ( 20 ) provide more functions: [0024] The power supply ( 10 ) has a temperature sensing circuit ( 11 ) with an output built therein, as shown in FIG. 5 , to detect the internal temperature of the power supply ( 10 ), and output the detected temperature signal to the A/D converter ( 22 ). The temperature signal is transformed to a numerical value, which is sent to be shown on the display ( 30 ). Meanwhile, the microprocessor ( 21 ) will determine if the temperature is excessively higher than normal, and if yes, the buzzer will be instructed to sound to alert the user. [0025] The cooling fan is mounted in the power supply ( 10 ), and generates a fan rotation speed signal send to the time/number counter ( 27 ) in a pulse form. The microprocessor ( 21 ) upon the speed signal determines if the rotation speed of the cooling fan is too fast or too slow. If the fan rotation signal is judged abnormal, the microprocessor ( 21 ) will give out a control signal to the power supply ( 10 ) through the D/A converter ( 26 ) to adjust the fan rotation speed. In addition, the fan rotation speed can also be controlled by the user through the control interface ( 201 ). In a situation that the output voltage of the D/A converter is 0-12V, and the fan control speed signal generated by the microprocessor ( 21 ) is 8 bits, i.e. as many as 2 8 =256 instructions can be made. The quantity of the instructions can be changed by the user, if the quantity of the instructions is set at 2 7 =128, the D/A converter will output a voltage of 6V, i.e. half of the full voltage. The voltage value per bit is calculated by a formula: (12V−0)/256=46.875 mV/bit); the output voltage will control the fan rotation speed. [0026] Data transmission via the transmission interface ( 29 ) between the control module ( 20 ) and the computer chassis ( 100 ) is in a communication protocol. A monitoring application program can be built in the computer operating system and linked with the control module ( 20 ). The monitoring application program can give an operating window shown on a desktop display been already connected to the computer, whereby the user can monitor the operation status of the power supply from the desktop display and make instructions for the control module ( 20 ) through the transmission interface ( 29 ) to determine the fan speed. [0027] Therefore, the control module ( 20 ) picks the signals about the operation status of the power supply ( 10 ), and then the result is shown on the display ( 30 ). [0028] With reference to FIG. 6 , a power supply with a performance display can also be applied in an adapter ( 40 ), which is a second embodiment of this invention. In that case, the adapter ( 40 ) serves as a power converter, and a control module is fixed inside the adapter ( 40 ). The display ( 30 ′) is mounted on a case of the adapter ( 40 ). [0029] FIG. 7 shows a circuit block diagram of the power supply with a performance display in the second embodiment. The control module ( 20 ′) of the power supply includes a microprocessor ( 21 ′), an A/D converter ( 22 ′), an external interrupt source ( 23 ′), a real time clock ( 24 ′), a memory ( 25 ′) and a control interface ( 201 ′). [0030] The microprocessor ( 21 ′) performs as an arithmetic and control unit. The A/D converter ( 22 ′) has multiple inputs that receive current signals, power signals, and temperature signals. The output of the A/D converter ( 22 ′) is connected to the microprocessor ( 21 ′) through a third internal bus. The external interrupt source ( 23 ′) is connected to the microprocessor ( 21 ′) through the third internal bus, by which the microprocessor obtains the POWER GOOD signal from the adapter ( 40 ) through the external interrupt source ( 23 ′). The real time clock ( 24 ′) is connected to the microprocessor ( 21 ′) through the third internal bus to count the total operation time of the adapter ( 40 ). The memory ( 25 ′) is also connected to the microprocessor ( 21 ′) to store some alarm setting value and total operation time. The control interface ( 201 ′) is connected to the microprocessor ( 21 ′) through a fourth internal bus, which can be in the form of a press key set. In this way, the power supply with a performance display is applied on the adapter ( 40 ). [0031] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.	A power supply with performance display is disclosed. The computer power supply mainly has a power converter, a control module, and a display. The control module receives and processes the operating signals from the power converter, and then sends those processed signals to a display in a numerical value form. The power supply can be applied in a computer, an adapter, or other electronic products, which is convenient for users to know the operating status of the power converter.	6
BACKGROUND OF THE INVENTION This invention relates to electromechanical transducers and more particularly to electromechanical transducers comprising microminiature elements and methods for their manufacture. Their principle of operation is the attraction of oppositely charged micro-elements which have been manufactured using high resolution fabrication methods developed for integrated circuit production. This allows the elements to be as small as the order of microns, and it allows the separation between capacitive elements to be of the order of microns. As will be seen, the actuation force is inversely proportional to the square of the separation distance, and it is large enough to be of practical use for the separations of the order of microns. A number of researchers have recently become active in the field of micro-machining. The most pertinent work for this patent is described in Copending application Ser. No. 07/619,183 filed Nov. 27, 1990 by co-inventor Stephen M. Bobbio and entitled "Microelectromechanical Transducer and Fabrication Method," the disclosure of which is incorporated herein by reference. Described is an electromechanical transducer which features a small separation between plates and which avoids the need for individual discrete wiring to each plate. The Bobbio transducer is formed of a plurality of electrically conductive strips arranged in an array, with adjacent portions of the strips being maintained in a closely spaced relation by a series of spacers positioned between the adjacent portions of the strips. The spacers have electrically conductive portions to distribute the electrical signal within the transducer, thereby forming an internal distribution network and obviating the need for discrete electrical connections to made to each conductive strip in the transducer. The strips are preferably made of flexible dielectric material having an electrically conductive layer on selected outer surfaces thereof. The dielectric strips and spacers are preferably formed from a common dielectric layer using microelectronic fabrication techniques to thereby greatly simplify fabrication and avoid the need for assembling a myriad of microscopic elements. The transducer of Bobbio was designed with the following goals in mind. Microelectromechanical transducers must be electrically and mechanically robust, so that they can be fabricated with high manufacturing yields and operated over extended periods of time without breakdown. In particular, because of the large numbers of electrical conductors which must be formed in a microelectromechanical transducer, the transducer should be designed so that electrical shorts do not occur during the manufacturing process and during operation over a normal lifetime. Moreover, the structure must be mechanically robust so that it can withstand the various manufacturing processes which are used to fabricate the structure, and can also withstand operation over an extended operational lifetime. Mechanical robustness is particularly important for microelectromechanical transducers, which by their very nature are required to move during normal operation. The manufacturing processes for the microelectromechanical transducer should also produce high yields for the device. The manufacture of these transducers should also preferably use processes and materials which have heretofore been widely used in the manufacture of similar devices such as integrated circuits. OBJECTIVES It is therefore an object of the present invention to provide an electromechanical transducer called here a microactuator having a large number of conductive plates with a small separation between adjacent plates. It is another object of the present invention to provide a microactuator which requires a small operating voltage and which avoids the need for individual discrete wiring to each component plate. It is yet another object of the present invention to provide a microactuator capable of a large and continuously variable displacement of the order of 20 to 50%, or more. It is yet another object of the present invention to provide a microactuator that is readily and economically fabricated using micro-electronics fabrication techniques. SUMMARY OF THE INVENTION This invention incorporates micro-machining fabrication techniques to achieve practical electrostatic actuation forces over a length change of the order of 20 to 50 percent. It constitutes an improvement over the prior art by virtue of array designs which yield a more versatile and stronger actuator. One basic design utilizes diamond-shaped attractive elements to transmit transverse forces for longitudinal, two-way actuation. Another basic design features interlocking, longitudinally attractive elements to achieve longitudinal, two-way actuation. Other improvements include means for locking the actuator at an arbitrary displacement as well as means for amplification of either the actuation force or length change. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified top view of a microactuator array showing diamond spacers for actuation according to the first embodiment of the invention. FIG. 2 is a top view of the top side of a microactuator array showing the wiring scheme according to the first embodiment of the invention. FIG. 3 is a top view of the bottom side of a microactuator array showing the wiring scheme according to the first embodiment of the invention. FIG. 4 is a silhouette front view of the diamond spacer elements of the microactuator showing only conductive strips according to the first embodiment of the invention. FIG. 5 is a partial schematic of the wiring of the microactuator showing switching configurations for expansion and attraction modes of actuation according to the first embodiment of the invention. FIG. 6 is a top view of the top side of a multi-diamond variation of the microactuator array showing the wiring scheme according to the second embodiment of the invention. FIG. 7 is a top view of the top side of an interlocking-L microactuator showing the wiring scheme according to the third embodiment of the invention. FIG. 8 is a top view of the bottom side of an interlocking-L microactuator showing the wiring scheme according to the third embodiment of the invention. FIG. 9 is a partial schematic of the wiring of the interlocking-L microactuator showing switching configurations for expansion and attraction modes of actuation according to the third embodiment of the invention. FIG. 10 is a top view of the top side of the staggered interlocking-T microactuator showing the wiring scheme according to the fourth embodiment of the invention. FIG. 11 is a top view of the bottom side of the staggered interlocking-T microactuator showing the wiring scheme according to the fourth embodiment of the invention. FIG. 12 is a partial schematic of the wiring of the interlocking-T microactuator showing switching configurations for expansion and attraction modes of actuation according to the fourth embodiment of the invention. FIG. 13 is a simplified top view of a non-staggered interlocking-T microactuator according to the fifth embodiment of the invention. FIG. 14 is a simplified top view of the an L-tree microactuator according to the sixth embodiment of the invention. FIG. 15 is a simplified top view of the a T-tree microactuator according to the seventh embodiment of the invention. FIG. 16 is a front view of an electrostatic-locking feature according to the eighth embodiment of the invention. FIG. 17 is a top view of an electrostatic-locking feature according to the eighth embodiment of the invention. FIG. 18 is a front view of an application of an electrostatic-locking feature according to the eighth embodiment of the invention. FIG. 19 is a top view of an application of an electrostatic-locking feature according to the eighth embodiment of the invention. FIG. 20 is a simplified front view of three layers of a microactuator showing vertical offsets for adjacent array elements according to the ninth embodiment of the invention. FIG. 21 is a schematic representation of two wiring schemes for use of the microactuator as a displacement sensor according to the tenth embodiment of the invention. FIG. 22 is a schematic representation of a first design for telescoping microactuators according to the eleventh embodiment of the invention. FIG. 23 is a schematic representation of a second design for telescoping microactuators according to the twelfth embodiment of the invention. FIG. 24 is a top view of an a levered microactuator in its contracted state according to the thirteenth embodiment of the invention. FIG. 25 is a side view of detail of a fulcrum hinge of the levered microactuator according to the thirteenth embodiment of the invention. DESCRIPTION The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein: rather, applicant provides these embodiments so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The basic idea of this invention is that adjacent rows, forming an array of beams or beam frames each of which has a width and a height, are forced together or apart by force elements, in a longitudinal direction. At the same time this array does not change size in the lateral dimension. Thus, the array changes length but not width. This is distinguished from the prior art of co-inventor Bobbio in which rigid posts connect adjacent rows of beams and in which both lateral and longitudinal dimensions change with actuation. FIG. 1 shows a simplified top view of microactuator array 1 showing force elements 4, also called bending spacers, for actuation according to the first embodiment of the invention. Force elements 4 connect adjacent beams 2; by bending, force elements 4 either pull the adjacent beams 2 together or push them apart, causing the entire microactuator array 1 to contract or to expand. Using current manufacturing methods, the thickness of these array elements can be of the order of several microns, and consequently a single layer of microactuator array 1 is a very thin sheet. This thin sheet may be appropriate for micro-applications, but to make a viable 3-d actuator for larger-scale applications, a number of these microactuator array 1 sheets must be either rolled up or stacked. Alternatively, one could take advantage of high aspect ratio manufacturing methods currently under development; these would extend the thickness of a single sheet to tens or even hundreds of microns, thereby reducing the need for rolling or stacking to achieve greater actuator force. FIG. 2 is a top view of the top side of microactuator array 1, and FIG. 3 is a top view of the bottom side of microactuator array 1, both showing the wiring scheme according to the first embodiment of the invention. Each pair of diamond spacers 3 forms a diamond shape, and each diamond spacer 3 is preferably dimensioned to bend primarily at the vertices of this diamond shape. Force elements 4 are comprised of a pair of diamond spacers 3. Each hammer-head forms the center of a diamond spacer 3. For example, first left hammer-head 28 and first right hammer-head 30 form the centers of one force element 4, and second left hammer-head 32 and second right hammer-head 34 form the centers of an adjacent force element 4. Microactuator array 1 is monolithically comprised of beams 2, diamond spacers 3 and hammer-heads 28-34 by virtue of x-y lithographic fabrication. In this fabrication a resilient material such as polyimide is first deposited on a substrate; subsequently, material is removed from this deposition layer to form the monolithic structure. Other steps in the fabrication lay down conductive layers on the top, the bottom, or the sides of the component layer elements. Attractive electrostatic force is exerted by conductive metal strips which have been deposited, at an angle, onto sides of the array structure, as indicated in FIG. 4, which is a silhouette front view of force element 4, showing only conductive layers according to the first embodiment of the invention. For example, hammer-head conductive strip 36 is fed by top or bottom connective conductive strips 40 or 42. Feeder line 8 connects one of inner conductive strips 38 to top busline 6, while feeder lines 46 and 20 connect both inner conductive strips 38 to bottom busline 5. Referring also to FIGS. 2 and 3, inner conductive strips 38 are located on the inner sides of force element 4. When the inner conductive strip 38 on one diamond spacer 3 is connected to a particular voltage, V, and when the other inner conductive strip 38 of the same diamond spacer 3 is connected to an opposite voltage, -V, an attractive force is exerted between these two inner conductive strips 38. This attractive force acts to push apart adjacent beams 2, to expand microactuator array 1. Hammer-head conductive strips 36 are located on the outer sides of force element 4 for the purpose of exerting maximum contraction forces. For example, when the hammer-head conductive strip 36 on first right hammer-head 30 is connected to a particular voltage, V, and when the hammer-head conductive strip 36 on the second left hammer-head 32 is connected to an opposite voltage, -V, an attractive force is exerted between the hammer-head conductive strip 36 on one force element 4 and the adjacent hammer-head conductive strip 36 on the adjacent force element. This attractive force acts to pull together adjacent beams 2 to contract microactuator array 1. Note that the two closest diamond spacers 3 in two adjacent force elements 4 could be constructed alone or could be considered to be an independent contractive force element. The wiring scheme is depicted in FIGS. 2-4 and in FIG. 5, which is a partial schematic of the wiring of microactuator array 1, showing switching configurations for expansion and attraction modes of actuation according to the first embodiment of the invention. Top busline 6 has been deposited on the top of beams 2, and bottom busline 5 has been deposited on the bottom of beams 2. Also, feeder lines 8, 10, 11, and 12 have been deposited on the top of beams 2 so as to electrically connect top busline 6 with inner conductive strips 38, and feeder lines 46, 20, 22, 26, and 47 have been deposited on the bottom of beams 2 so as to electrically connect bottom busline 5 with inner conductive strips 38. And, top and bottom connective conductive strips 40 and 42 have been deposited on either the top or bottom of hammer-heads 28-34, for the purpose of connecting hammer-head conductive strips 36 to buslines 5 or 6 via inner conductive strips 38. Note that the wiring scheme depicted in FIGS. 2 and 3 is based on pairs of force elements 4, or a left force element 4 and a right force element 4, and the wiring scheme is based on alternating pairs of top buslines 6 labeled A and B or alternating pairs of bottom buslines 5 labeled AA and BB. Finally, microactuator array 1 is comprised of an array of such pairs of elements. Looking at FIG. 2, top busline 6-A is connected to the left inner conductive strip 38 of the left force element 4 via feeder line 8. Top busline 6-B is connected to the right inner conductive strip 38 of the left force element 4 via feeder line 9. Top busline 6-A is connected to the right inner conductive strip 38 of the right force element 4 via feeder line 10. Top busline 6-B is connected to the left inner conductive strip 38 of the right force element 4 via feeder line 11. Also, top connective strips 40 electrically connect the various hammer-head conductive strips 36 to the their neighbors which are the various inner conductive strips 38. Looking at FIG. 3, bottom busline 5-AA is connected to the right inner conductive strip 38 of the left force element 4 via feeder line 20. Bottom busline 5-AA is connected to the left inner conductive strip 38 of the left force element 4 via feeder line 46. Bottom busline 5-BB is connected to the right inner conductive strip 38 of the right force element 4 via feeder line 22. Bottom busline 5-BB is connected to the left inner conductive strip 38 of the right force element 4 via feeder line 48. Also, bottom connective strips 42 electrically connect the various hammer-head conductive strips 36 to the their neighbors which are the various inner conductive strips 38. Careful inspection of FIGS. 2-4 and FIG. 5 reveals that when the various buslines are switched according to the expansion mode, microactuator array 1 expands, and when the various buslines are switched according to the contraction mode, microactuator array 1 contracts. For expansion, the buslines labeled A are connected to +V and the buslines labeled B are connected to -V. For contraction, the buslines labeled AA are connected to +V and the buslines labeled BB are connected to -V. It should be understood that microactuator array 1 could be designed to function only as an expansion actuator or only as a contraction actuator; in the preferred embodiment it is, however, a bi-directional actuator. FIG.6 is a top view of the top side of a multi-diamond variation of microactuator array 1 showing the wiring scheme according to the second embodiment of the invention. FIG.6 is equivalent to FIG. 2 except that the single diamond spacers 3 of FIG. 2 have been replaced by multiple diamond spacers 62. Outer conductive strips 56 are analogous to hammer-head conductive strips 36, and multiple connective conductive strips 68 are analogous to top or bottom connective conductive feeder lines 40 and 42. The second embodiment allows the attractive elements, namely multiple inner conductive strips 60 and multiple outer conductive strips 56, to lie closer together over the entire range of expansion or contraction than is the case for the first embodiment. That is, multiple inner conductive strips 60 are separated by a characteristic distance range of 0 to 2d, whereas inner conductive strips 38 that would be on the single diamond spacer 64, shown in phantom, would be separated by a characteristic distance range of 0 to 2D. The same is true for the attractive forces between multiple outer conductive strips 58. Since the attractive elements are closer together, the forces are greater and the actuator is stronger. FIG. 7 is a top view of the top side of interlocking-L microactuator array 50 showing the wiring scheme according to the third embodiment of the invention. FIG. 8 is a top view of the bottom side of interlocking-L microactuator array 50, and FIG. 9 is a partial schematic of the wiring of interlocking-L microactuator array 50 showing switching configurations for expansion and attraction modes of actuation. Beams 2, first interlocking-L element 70, second interlocking element 72, and extensible positioners 86 are monolithically formed from a solid layer of x-ray lithographically deposited material such as polyimide. Extensible positioners 86 constrain first and second interlocking-L elements 70 and 72 to the plane of interlocking-L microactuator array 50, while, at the same time, they allow these elements to move longitudinally together and apart. Careful inspection of FIG. 7 reveals that when the following conductive elements are connected to voltages of opposite polarity the resulting attractive forces cause interlocking-L microactuator array 50 to expand: first-L lower conductive strip 78 and second-L upper conductive strip 80. In contradistinction, when the following two pairs of conductive elements are connected to voltages of opposite polarity the resulting attractive forces cause interlocking-L microactuator array 50 to contract. The first pair is beam lower conductive strip 74 and first-L upper conductive strip 76; the second pair is second-L lower conductive strip 82 and beam upper conductive strip 84. To achieve these expansion and contraction modes, the following wiring details are made. Looking at FIG. 7, beam lower conductive strip 74 and beam upper conductive strip 84 are electrically connected to bottom busline 5-AA via bottom feeder line 94; first-L upper and lower conductive strips 76 and 78 are electrically connected to top busline 6-B via first-L top feeder line 88; and second-L upper and lower conductive strips 80 and 82 are electrically connected to top busline 6-A via second-L top feeder line 90. FIG. 9 shows the wiring connections between the various buslines and external voltages, ±V, to achieve the expansion and contraction modes indicated above. It should be understood that, as with the first embodiment, the various connective conductive strips or feeder lines have been deposited on the top or bottom sides of the various elements of interlocking-L microactuator array 50, and the various conductive strips used for electrostatic attraction have been deposited at an angle on the sides of these various elements. The fourth embodiment is similar to the third embodiment with interlocking L-shaped members, except that a T-shaped member interlocks within an inverted U-shaped member, to achieve attractive forces. FIG. 10 is a top view of the top side of staggered interlocking-T microactuator array 101 showing the wiring scheme according to the fourth embodiment of the invention. FIG. 11 is a top view of the bottom side of staggered interlocking-T microactuator array 101 and FIG. 12 is a partial schematic of the wiring of staggered interlocking-T microactuator array 101 showing switching configurations for expansion and attraction modes of actuation. T-frame 100, inverted-U frame 102, and extensible positioners 86 are monolithically formed from a solid layer of x-ray lithographically deposited material such as polyimide. Extensible positioners 86 constrain T-frame 100 and inverted U-frame 102 to the plane of interlocking-T microactuator array 101, while, at the same time, they allow these elements to move longitudinally together and apart. Note that the adjacent array elements comprising T-frame 100, inverted-U frame 102, and extensible positioners 86 are staggered with respect to each other. This makes T-stem 116 less likely to break. T-stem 116 interlocks with inverted U-frame bottom section 125. Careful inspection of FIG. 10 reveals that when the following conductive elements are connected to voltages of opposite polarity the resulting attractive forces cause interlocking-T microactuator array 101 to expand: T lower conductive strip 106 and lower T-beam upper conductive strip 112. In contradistinction, when the following two pairs of conductive elements are connected to voltages of opposite polarity the resulting attractive forces cause interlocking-T microactuator array 101 to contract. The first pair is upper T-beam lower conductive strip 110 and T upper conductive strip 104; the second pair is lower T-beam lower conductive strip 114 and upper T-beam upper conductive strip 108. To achieve these expansion and contraction modes, the following wiring details are made. Looking at FIG. 10, T upper and T lower conductive strips 104 and 106 are electrically connected to first top busline 118-A via second top feeder line 127; and lower T-beam upper and lower conductive strips 112 and 114 are electrically connected to top busline 120-B via first T-top feeder line 126 and via third top feeder line 128. Looking at FIG. 11, upper T-beam lower conductive strip 110 is electrically connected to second bottom busline 123-BB via second bottom feeder line 130; and upper T-beam upper conductive strip 108 is electrically connected to first bottom busline 122-AA via first bottom feeder line 129. FIG. 12 shows the wiring connections between the various buslines and external voltages, ±V, to achieve the expansion and contraction modes indicated above. It should be understood that, as with the first embodiment, the various connective conductive strips or feeder lines have been deposited on the top or bottom sides of the various elements of interlocking-T microactuator array 101, and the various conductive strips used for electrostatic attraction have been deposited at an angle on the sides of these various elements. FIG. 13 is a simplified top view of non-staggered interlocking-T microactuator array 103 according to the fifth embodiment of the invention. It shows a given array element comprising T-frame 100, T-top 124, and inverted U-frame bottom section 125 which is not staggered with respect to its adjacent array element. It should be understood that the three primary embodiments, namely those of FIGS. 2-5, of FIGS. 7-9, and of FIGS. 10-12, can be wired to actuate "one-way" with buslines only on the top of the array. For example, each embodiment could only expand, or only contract, with the top-only wiring. This alternative wiring, which is easier to implement, would, however, require conductive strips along the tops of extensible positioners 86 for the second and third of these primary embodiments. FIG. 14 is a simplified top view of the L-tree microactuator array 135 according to the sixth embodiment of the invention. It is similar to the third embodiment of FIGS. 7-9 in terms of the type of interlocking of L-shaped elements and in terms of the wiring scheme; the difference is that each interlocking element is now a tree with multiple branches. That is, lower L-tree 131 comprising multiple L-tree branches 133 interlocks with upper L-tree 132 also comprising multiple L-tree branches 133. Attractive forces between adjacent conductive strips 119 cause contraction or expansion. An alternative configuration is shown on the right side of FIG. 14 where force elements 4 interconnect multiple L-tree branches 133 and either push them apart for expansion or pull them together for contraction. An additional feature utilizes first guide 140 and second guide 142 to prevent lower L-tree 131 and upper L-tree 132 from tilting and binding with respect to each other. Note that the force exerted by L-tree microactuator array 135 is roughly increased by a factor equal to the number of branches, while the displacement is decreased by the same factor. FIG. 15 is a simplified top view of T-tree microactuator array 137 according to the seventh embodiment of the invention. It is similar to the fourth embodiment of FIGS. 10-12 in terms of the type of interlocking of T-shaped elements and in terms of the wiring scheme; the difference is that each interlocking element is now a tree with multiple branches. That is, T-tree 134, comprising T-tree branches 136, interlocks with T-tree frame branches 139, which extend from T-tree frame 138. Attractive forces between adjacent conductive strips 119 cause contraction or expansion. It should be understood that force elements 4 could be used to interconnect multiple T-tree branches 136 and T-tree frame branches 139, as was portrayed in FIG. 14. Note again that the force exert by T-tree microactuator array 137 is roughly increased by a factor equal to the number of branches, while the displacement is decreased by the same factor. FIG. 16 is a front view of electrostatic-locking means 141 according to the eighth embodiment of the invention, and an example from previous embodiments is indicated in FIG. 14. First guide 140 and second guide 142 may be parallel strips of a generic microactuator array. First guide conductive strip 143 and second guide conductive strip 144 have been deposited on the sides facing each other of first guide 140 and second guide 142, respectively. Insulating films 145 have been deposited over first and second guide conductive strips 143 and 144 for electrical insulation in case these should touch. Guide connective conductive strips 148 connect first and second guide conductive strips 143 and 144, with both of these being located on the top side (or bottom side) of electrostatic locking means 141. Arrows 146 show the direction of the attractive electrostatic force when first guide conductive strip 143 is connected to a voltage opposite in polarity to that connected to second guide conductive strip 144. At this time first and second guides 140 and 142 are pulled to bind together, thereby locking a generic microactuator array at a fixed position of length change, irrespective of an external load. Arrows 147 show the direction of the repulsive electrostatic force when first guide conductive strip 143 is connected to a charge source of the same polarity as that connected to second guide conductive strip 144. At this time first and second guides 140 and 142 repel each other, thereby acting as a frictionless bearing which allows generic microactuator array to freely change its length according to external load. FIG. 17 is a top view of an application of electrostatic-locking means 141 according to the eighth embodiment of the invention. First finger guide 150 extends downward from a beam 2, while second finger guide 151 extends upward from the lower adjacent beam 2, parallel to and overlapping with first finger guide 150. Again, the inward sides have been deposited with first and second guide conductive strips 143 and 144. And again, when the beams 2 of a generic microactuator array move either together or apart as shown by arrows 146 or 147, respectively, first and second finger guides 150 and 151 can be caused to act as a lock or as a bearing for this motion. FIGS. 16 and 17 for the eighth embodiment feature conductive strips on the sides of the guide elements. It is also possible to achieve locking by use of offset guide members which have conductive strips on their bottom or top sides. FIG. 18 is a front view of an electrostatic-locking means 141 comprising upper layer guide 162 which is adjacent to and integrally part of first frame finger 160. These move along lower layer guide 163 which is adjacent to and integrally part of second frame finger 161. Upper and lower conductive strips 164 and 165 provide the electrostatic locking. FIG. 19 is a top view of an application of electrostatic-locking means 141 according to the eighth embodiment of the invention. It is similar to the example of FIG. 17 except that it would be located at the end of a row or subsection of microactuator array 1. First frame 154 is comprised of a pair of beams 2, and second frame 155 is comprised of an adjacent pair of beams 2; first and second frames 154 and 155 are rigidly connected by posts 156. The pair of beams 2 comprising first frame 154 are connected at their ends by first frame end post 160; the pair of beams comprising second frame 155 are connected at their ends by second frame end post 161. First end guide 157 is rigidly attached to first frame end post 160, while second end guide 158 is rigidly attached to second end post 161, in such a manner as to run parallel and to overlap with first end guide 158. As with the embodiment of FIG. 16, first guide conductive strip 143, on the inside of first end guide 157, and second guide conductive strip on the inside of second end guide 158, make possible a lock or a bearing for the contractive or expansive motion of a generic microactuator array; this actuator motion is indicated by arrows 159. FIG. 20 is a simplified front view of three stacked layers of a generic microactuator array 1 showing vertical offsets for adjacent array elements according to the ninth embodiment of the invention. Beam element 166, such as beam 2 from FIG. 1, has a greater thickness, d2, than thickness, d2, of adjacent beam element 167 (in the same layer), which moves relative to beam element 166. This difference in thickness ensures that any adjacent beam elements 167 int one layer will not bind on components of other beam elements 166 or adjacent beam elements 167 in the stacked layers above or below. FIG. 21 is a schematic representation of two wiring schemes for use of microactuator array 1 as a displacement sensor according to the tenth embodiment of the invention. Capacitive elements 172 might be any pair of adjacent conductive strips connected to voltages of opposite polarity, such as inner conductive strips 38 or hammer-head conductive strips 36 of FIG. 2. If these are interconnected as shown on the left side of FIG. 21 and probed by a capacitance meter via series leads 173, the inverse of the measured total capacitance is the sum of the inverses of the individual component capacitances. Since each individual component capacitance is approximately proportional to the inverse of the distance between each pair of conductive strips forming a capacitive element, the total measured capacitance is proportional to the inverse of the total distance between individual elements of microactuator array 1. If the total capacitance is probed in parallel as shown in the right side of FIG. 21, via first parallel busline 174 and second parallel busline 175, the total measured capacitance is proportional to the sum of the reciprocals of distances between individual elements of microactuator array 1. If these individual distances are fairly constant over the measured length of microactuator 1, this total measured capacitance can give a good estimate of the length of microactuator array 1. FIG. 22 is a schematic representation of a first design for telescoping microactuator arrays 181 according to the eleventh embodiment of the invention. The purpose of this embodiment is to amplify actuator displacement which may be a consideration in applications where the original length of an actuator is constrained to a small value. Beginning at the left side of telescoping microactuator array 181, each successive expansive element 180 is rigidly attached from its bottom end to the top end of the previous expansive element 180 by first telescopic connector 183. As shown on the right side of FIG. 22, when each expansive element 180 expands according to arrows 179 the displacement of the rightmost expansive element 180 is N times the displacement of a single expansive element 180. FIG. 23 is a schematic representation of a second design for telescoping microactuator array 181 according to the twelfth embodiment of the invention. It is similar to the previous embodiment except that contractive elements 182 form the connection between the top of one expansive element 180, via first telescopic connector 183, and the bottom of its neighbor to the right, via second telescopic connector 184. Now, when expansive elements 180 expand according to expanding arrows 185 and when contractive elements 182 contract, according to contracting arrows 186, the resulting displacement of the rightmost expansive element 180 is the sum of all the displacements of the component expansive elements 180 and contractive elements 182. This is shown on the right side of FIG. 23. It should be understood that the configuration of the various component actuators of a telescoping system could vary from one side to another, from outside to inside, or according to a cylindrical geometry. Also, the telescopic elements could act at the level of an individual force element 4 or at larger modular levels. FIG. 24 is a top view of levered microactuator array 195, according to the thirteenth embodiment of the invention. It is similar in configuration and wiring to the first embodiment of FIG. 1 except that a lever principle is utilized to amplify displacement. The top of force element 4 is monolithically connected to lever 189 via first hinge 187. The other end of lever 189 is attached to beam 2 via second hinge 188. Lever 189 acts about fulcrum 191 via fulcrum hinge 190. The various hinges here are monolithic with their adjoining elements. Detail of fulcrum 191 is shown in FIG. 25, which is a side view fulcrum 191. Fulcrum 191 must be rigidly attached to the lower of the two beams 2 shown. This is accomplished by fulcrum layer 192 which lies at a level indicated by fulcrum layer location 194 which is below actuator layer location 193, which is the level for the components shown in FIG. 24. Fulcrum layer 192 is in turn monolithically attached to the lower of the two beams 2 shown.	This invention incorporates micro-machining fabrication techniques to achieve practical electrostatic actuation forces over a length change of the order of 20 to 50 percent. It constitutes an improvement over the prior art by virtue of array designs which yield a more versatile and stronger actuator. One basic design utilizes diamond-shaped attractive elements to transmit transverse forces for longitudinal, two-way actuation. Another basic design features interlocking, longitudinally attractive elements to achieve longitudinal, two-way actuation. Other improvements include means for locking the actuator at an arbitrary displacement as well as means for amplification of either the actuation force or length change.	7
REFERENCE TO RELATED U.S. APPLICATIONS This application is a continuation-in-part of application Ser. No. 08/146,813, filed Nov. 3, 1993. BACKGROUND OF THE INVENTION The present invention relates to an improved method for installing a resin-grouted anchor bolt in a borehole, and, more particularly, to an improved method of quickly securing an anchor bolt or cable in a borehole using a settable bonding material. The improvement comprises heating the bolt to a temperature at least approximately 40° above ambient temperature prior to contacting the bolt and bonding material during the installation procedure whereby curing is accelerated, and the bolt is placed under tension without mechanical torquing. In the art of bolt anchoring systems, and especially in mine roof support, it is well known how to tension bolts by the use of a shell-type, plastic or metallic-sleeve mechanical expansion system with and without resin. Non-mechanical anchor bolts of the type which are installed with a settable bonding material are normally placed under tension after the bonding material has reached a predetermined initial cure strength by torquing a nut or a bolt on the exposed bolt end. Popular bonding materials; e.g., polyesters, epoxies, and other known commercially available synthetic resins, are typically provided in packages in which the resin and a catalyst for the resin are separated by a package film or reacted zone of the resin. During normal installation when the anchor bolt, or anchor bolt assembly, is forced into a drilled borehole which already contains the resin/catalyst package, the bolt breaks the package and then mixes the resin and catalyst as it is rotated from 30 to about 100 revolutions at a rate of 150 rpm to 1200 rpm. At ambient mine temperatures, which can range from 3° to 35° C., the elapsed time from insertion of the bolt until the resin reaches a satisfactory cure strength and can be torqued into tension can range from 14 seconds up to about 60 seconds. Another method of securing a bolt or cable utilizes cementitious materials. Cementitious materials, packaged for water soaking or pumpable, are used in securing bolts and cables in various geological strata. Packaged cementitious materials are soaked in water prior to inserting into the borehole. The bolt or cable is then installed through the cementitious material. Alternatively, the bolt or cable is installed first followed by pumping the cementitious material into the hole to grout the system. U.S. Pat. No. 4,353,463, issued Oct. 12, 1982 to R. W. Seemann, discloses a cartridge assembly of a multicomponent curable system for use in anchoring bolts into solid structures wherein preheating the cartridge and/or the bolt can reduce reaction time. In such a system, the resin curing time is less than the bolt warming time and, therefore, the bolt goes into compression and the solid structure goes into tension. There is a need to achieve the opposite effect, that is, for the bolt to go into tension and the solid structure to go into compression. To achieve that, there is a need for a system where resin curing time is less than bolt cooling time. SUMMARY OF THE INVENTION The present invention provides an improved method for anchoring a bolt under tension in a borehole comprising the steps of: (a) introducing a curable bonding material into a borehole wherein said material is compartmentalized prior to introduction to prevent curing; (b) heating a bolt to a temperature at least 40° C. above ambient temperature prior to insertion into said borehole; (c) inserting and rotating the heated bolt into the borehole thereby mixing the components of said bonding material; and (d) keeping the bolt stationary for a time sufficient to allow the bonding material to reach minimum cure strength. The improvement according to the present invention comprises heating a bolt either partially or its entire length to a temperature in the range of at least 40° C. above ambient mine temperature prior to insertion into the borehole whereby curing of a resin or cementitious material present in the borehole to a satisfactory initial cure strength is accelerated. Slow cooling of the bolt thereafter places it under tension without the need for a separate torquing step. The elapsed time from bolt insertion until the bonding material reaches its minimum satisfactory initial cure strength is reduced to about 3 to 7 seconds in torque tension and combination bolt applications. The process of this invention substantially reduces overall installation time per bolt and helps to achieve the stress distribution characteristics of a tensioned grouted bolt support system without the need for a separate bolt torquing step. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a typical partially grouted torque tension roof bolt after bolt torquing. FIG. 2 is a sectional view of a resin grouted bolt installed according to the invention. DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement in the method for installing grouted cable or anchor bolts using a bonding material such as a compartmented resin-catalyst package which comprises heating the anchor or bolt to a temperature at least 40° C. above ambient mine temperature. The upper temperature is limited by the deterioration temperature of bonding material prior to inserting it into a borehole. A typical installation procedure of the prior art for installing (roof) anchor bolts or cable bolts in an underground mine comprises the steps of: (a) drilling a borehole of suitable diameter in the range of from 5/8 inch to 13/8 inch (1.6 cm to 5.7 cm) and depth of from about 1 foot up to 20 feet (30.5 cm to 610 cm); (b) introducing a bonding material into the borehole, usually contained in a two-compartment package in which one compartment contains a curable material and the other compartment contains a catalyst; (c) inserting an anchor bolt into the borehole thereby rupturing the divider between the compartments of the package and breaking open the package; (d) spinning the bolt to mix the curable material and catalyst into a substantially homogeneous mass; (e) holding the bolt stationary, e.g., for about 14 to 22 seconds, to achieve partial setting of the grout, thereby reaching an initial minimum cure strength; and (f) torquing the bolt to place it under tension. By heating the bolt according to the present invention prior to insertion into the borehole, the grouting material reaches its satisfactory initial cure strength and places the bolt under tension as it contracts during cooling without the need for a separate bolt torquing step. "Heating the bolt" means that all or a portion of the elongated shank of the bolt is heated to a preselected temperature. This way at least a portion of the heated bolt will come in contact with the bonding material in the borehole. The bonding material must cure sufficiently fast so as to achieve sufficient strength to bond the bolt to the borehole wall prior to substantial cooling of the bolt. It is only this way that the bolt can go into tension and the roof into compression. For example, if the bolt is heated approximately 100° C. above the roof (rock) temperature and it then cools to approximately 50° C. above ambient temperature prior to the curing of the grouting material, approximately one-half of the possible tension would be lost. On the other hand, if the bolt only cools to approximately 98° C. above ambient temperature, then approximately 98% of the tension would be retained. As a general proposition, it is preferable that the bolt cools less than 15% of its temperature above ambient temperature prior to the curing of the grouting material. Anchor bolts of the type contemplated for use according to the invention are typically deformed carbon steel bars (rebars) configured, e.g., threaded, at one end with a detachable nut or other convenient means, for rotation using a machine-driven socket. The configured end of the anchor bolt can also include an enlarged washer or roof plate which can improve distribution of stresses along the mine roof surface. The exact configuration of the bolt or bolt assembly can vary widely depending on the manufacturer and the preference of the mine operator. However, since roof support in an underground mine can account for up to 30% of the total cost of mine operation, the cost of materials and installation time; i.e., bolt "cycle time", are two critical factors which influence which bolt configuration is used and whether installation includes a settable bonding material. Typically, installation time for a resin-grouted bolt tends to exceed installation time for a non-grouted mechanical shell, plastic or metallic-sleeve expansion bolt while a resin-grouted bolt is known for more effective distribution of stress in a given rock formation and for durability. Referring now to the figures, FIG. 1 is a sectional view of a typical partially grouted "torque-tension" roof bolt of the prior art after bolt torquing. Bolt 10 as shown is a deformed carbon steel bar which can vary in diameter from 5/8 inch to 13/8 inch (1.6 cm to 3.5 cm) and from about 1 foot up to 20 feet in length (30.5 cm to 610 cm). A curable bonding material 13 fills the inward portion of the annular space between the bolt and borehole 12. The exposed end of the anchor bolt includes a nut 14, a washer 16, and a roof plate 18. Nut 14 will not spin independently of the nut/bolt assembly until after a shear device is broken by rotating at the nut after the bolt spin time and the hold time. After the hold time, the nut is rotated to break the shear device and tighten it to place the nut/bolt assembly under tension. Typical shear devices can break at 75, 100 or 120 ft-lbs. as desired. The shear device can be a shear pin or a dome on the end of the nut. A fully grouted roof anchor bolt, or the partially grouted bolt as shown, can provide excellent roof support. The tensioned bolt shown in FIG. 1 also includes an exposed thread portion 20. The exposed end of bolt 10 is threaded so that turning nut 14 after grout 13 has reached an initial cure strength will place the bolt under tension. If, however, nut 14 is torqued prematurely; i.e., before grout 13 can reach a satisfactory minimum cure strength, bolt 10 can be pulled out of borehole 12 as nut 14 is turned and advances along threads 20. The exposed threads can become a safety hazard especially in low roof coal mines. FIG. 2 is a sectional view of a fully grouted tensioned anchor bolt which has been installed according to the present invention. The bolt comprises a deformed carbon steel bar 21 with the exposed end configured with a bolt head 24 for rotating the bolt to mix the resin components to a substantially homogeneous bonding material 23. As with the partially grouted bolt shown in FIG. 1, the fully grouted anchor bolt 21 includes a washer or bolt head shoulder 26 and a roof plate 28. The anchor bolt installed and placed under tension according to the invention has no exposed threads and can be partially or fully grouted as shown. Bonding materials useful in practicing the invention can be any of a variety of inorganic or organic curable compositions depending on a number of factors, such as the nature of the rock formation, cost, availability and preference of the mine operator. Such bonding materials include cementitious grout and multicomponent organic systems capable of hardening upon mixing the components or upon exposure to moisture or air. Organic systems generally can include an unsaturated polyester resin, monomers, promoters, inhibitors, thickeners, and catalysts. The resins can be based on anhydrides such as maleic anhydride and phthalic anhydride and glycols such as propylene glycol and ethylene glycol. Promoters include N,N-dimethylaniline and N,N-dimethyltoluidine; inhibitors include hydroquinone, naphthaquinone, t-butylcathecol and t-butylhydroquinone. Catalysts are generally peroxides such as benzoyl peroxide. Often, both the resin and catalyst compartments contain limestone particles as a filler to transmit load. Bonding materials both prior to and subsequent to curing are often referred to as grout. Best results are usually achieved using organic grouting compositions of the type described in U.S. Pat. No. 4,280,943, incorporated herein by reference. In a preferred embodiment the grout is a catalyzed polyester resin available commercially under the name Fasloc® (a registered trademark of E. I. du Pont de Nemours and Company). The resin component occupies one compartment and the catalyst component occupies an adjoining compartment of a two-compartment frangible "chub" cartridge, such as that described in U.S. Pat. Nos. 3,795,081 and 3,861,522. The ratio of resin to catalyst and the presence of additives and other fillers are not critical to the method of this invention and can vary widely over a broad range. The cartridge can be made from various materials such as polyethylene terephthalate film which can break as the anchor bolt is inserted into the borehole, allowing the two components to mix together. Rotation of the bolt immediately upon insertion of the bolt for about 30 to 50 revolutions at a rate of from 300 rpm to 500 rpm insures thorough mixing of the components into a substantially homogeneous quick-curing grout. Once a borehole has been drilled, one or more resin cartridges can be inserted followed immediately by the anchor bolt. Insertion of the bolt can be conveniently accomplished using a bolting machine specially designed with a machine-driven socket for engaging the configured end of the bolt and upwardly thrusting the bolt into the borehole. These machines are widely available in the mining industry. Typically, the time needed for commercially available catalyzed grouting systems to reach a minimum cure strength sufficient for bolt torquing and thereafter to support the bolt when the upward force of the bolting machine is released, measured from the instant the bolt is thrust into the borehole, can range from a low of 12-14 seconds up to 22 seconds. This is referred to as "bolt cycle time". According to the present invention, bolt cycle time can be substantially reduced by heating the bolt along the shank portion to a temperature in the range of from approximately 66° C. to 155° C. prior to inserting it into the borehole. The elevated temperature of the bolt accelerates the curing rate of the catalyzed grouting system so that the grout will reach a satisfactory minimum cure strength in the range of approximately from 4.5 to 9 metric tons substantially sooner than it would utilizing customary installation procedures. Because of this, the bolting machine can be released sooner to install the next bolt. Depending on the type of anchor bolt utilized and the length of the portion of the bolt heated, the bolt can be torqued to develop tension in addition to the tension imparted to the bolt as it cools. Alternatively, as the anchor bolt contracts as it cools, it is thereby placed under tension without the need for a separate bolt torquing step. Although several means are available for heating anchor or cable bolts and/or bonding materials, preferred for use in underground mines is an electric induction heating device. Friction, convective and direct heating systems can also be used. In the Examples which follow, "gel time" of a given resin formulation is the time that elapses between the mixing of the reactive components and the reaching of minimum cure strength. Gel times can be influenced by several factors such as by the use of promoters, inhibitors and by varying the initiator concentration. Cartridges containing different formulations having different gel times in the same cartridge have been developed for long bolt applications. Alternatively, two separate cartridges, one having a fast set gel time and one cartridge having a slower gel time, can be utilized with long bolts. In such cases, the faster fast gel time cartridge is inserted first, followed by the slower one prior to the insertion of the bolt improved bolt cycle time. In the process of this invention, utilizing a heated bolt system, one can achieve the desired results with one standard gel time system by heating the bolt in specific designated areas. The following are commonly accepted definitions and are referred to in the Examples which follow. "Gel time" is a rating test and is correlated to "in-hole" performance. It is a laboratory measurement by physically mixing a ratioed weight of catalyst to resin until the material begins to gel. The material is considered gelled when it becomes hard. The test is conducted at ambient temperatures and extrapolated to 55° F. which is the normal mine temperature. The time from beginning the mixing until the resin reaches a hard state is the gel time. "Borehole gel time" is measured as follows: A resin cartridge is placed in a steel borehole. A rebar bolt is installed into the steel borehole through the resin. The bolt is rotated while the steel borehole is stationary. The rotation is continued until the resin reaches adequate strength to stall out the bolt installation machine which is supplying 400 ft-lbs. of torque. The time from beginning the bolt rotation until stalling the machine (lock-up) is the borehole gel time (BGT). "Bolt-Spin Time" is the time of bolt rotation after it is inserted through the resin to mix the resin and catalyst components. Bolts are rotated at 500 rpm. EXAMPLE 1 In this example, bolt cycle times were compared with and without heating the anchor bolt, for the selected resin of fully grouted bolts to reach a minimum satisfactory cure strength using one-minute and 30-second gel time resins. One inch ID pipe (2.5 cm), four feet long (122 cm) was used as simulated boreholes. The bolts were 3/4 "rebar (1.9 cm) four feet long (122 cm) with a fixed nut on the exposed end. Each bolt had a 2" square (5.1 cm) washer above the nut. One-half of the bolts were heated in an electric furnace to an average temperature of 175° F. (79° C.). In each case, a 11/2 feet (46 cm)-portion of the bolt, the portion coming in contact with the grout, was heated. In each run, first a resin cartridge and then the anchor bolt were inserted upwardly into the simulated borehole. The top of the borehole was fixed against a steel plate, and the head of the bolt was engaged by the socket of a bolt driving machine. The upward force of the machine drove the bolt through the resin cartridge, and rotated the bolt rapidly for about 30 to 50 revolutions (at a rate of about 500 rpm) to mix the resin. Rotation was continued until the resin hardened (cured) sufficiently to stop the machine at a pre-set torque of 400 foot pounds. This time period is referred to as borehole gel time (BGT). Table I gives the results of these tests, each test representing an average of 3 bolt installations; utilizing the process of this insertion reduced total installation time (bolt anchoring) by over 40% (and insertion time by over 20%). This is necessary to insure that the resin cured sufficiently prior to substantial cooling of the bolt. TABLE I______________________________________ Bolt Temperature 72° F. (22° C.) 175° F. (79° C.)______________________________________ 30 Second ResinInsertion Time (sec) 7.7 6Borehole Gel Time (sec) 10.7 5Totals (sec) 18.4 11 1 Minute ResinInsertion Time (sec) 7.7 6Borehole Gel Time (sec) 19.7 8.3Total (sec) 27.4 14.3______________________________________ The data in Table I indicate that the resin reached adequate cure strength prior to the bolt cooling by more than 15% of its elevated temperature thereby providing for the bolt to go into tension. EXAMPLE 2 This example covers tension development upon bolt cooling. Bolts are shown in FIG. 2 were used as follows. The bolts were 4 feet long (122 cm) and 3/4 inch (1.9 cm) in diameter and for each test were inserted into a simulated borehole which was 4 feet long (122 cm) and 1 inch (2.5 cm) in diameter. Each bolt had a forged head on the exposed end for engagement by the socket of a bolt driving machine. The bolts were heated to 200° F. (93° C.) over their entire length. Different bonding materials, 15-sec. and 30-sec. gel time resins, FASLOC B-Fast resins, available from E. I. du Pont de Nemours and Company were inserted into the borehole either into 2-foot or 4-foot portions, immediately followed by a bolt with a hydraulic load cell. After bolt insertion through the resin was completed, each bolt was spun to mix the bonding material. Full up-thrust was applied to the bolts and held to allow adequate resin strength development. "Hold Time" is the time period after mixing (bolt spin time) has stopped, when full upthrust is applied, at 5700 lb, to the bolt head and when full upthrust to the bolt head is stopped. While the initial upthrust is applied at 5700 lb, the initial tension value shown in Table II is the value measured upon release of the upthrust force. Theoretically the applied upthrust and measured upthrust upon release should be identical, in practical applications, however, there can be some diminishing of the force. As the bolts cooled, tension increased in the bolts as indicated by the hydraulic load cell. There was no torque applied to develop tension, tension actually developed by bolt contraction over the entire length of the bolts and was measured 30 min. after installation was complete ("final tension"). Results are tabulated in Table II: TABLE II______________________________________ HoldBonding Material Bolt Spin Time Tension (lb)Gel Time (sec.) Length (ft.) Time (sec.) (sec.) Initial Final______________________________________30 4 2 18 5700 800015 2 2 10 3400 740030 4 3 15 5700 915015 2 3 10 4300 860015 4 4 10 4600 830015 4 4 10 4600 8200______________________________________ As can be seen from the above, tension increased in the bolt system gradually over a 30-min. period utilizing the anchoring method of this invention. The increase was at least approximately 40% under this particular set of conditions and, in general, amounted to approximately 1-2 ton over the initial (base) load. Prior systems do not provide tension increase over time in bolting systems unless the bolt is torqued after curing the bonding material. Such torquing would also require additional threaded parts on the bolt. In contrast, when the resin cartridge was heated to 157° F. (69.4° C.) and the bolt and steel borehole were at ambient temperatures, the data shown in Table III were obtained. Installation procedure was identical to that used above in obtaining data for Table II. TABLE III______________________________________ HoldBonding Material Bolt Spin Time Tension (lb)Gel Time (sec.) Length (ft.) Time (sec.) (sec.) Initial Final______________________________________30 4 5 20 5700 392030 4 5 20 4630 2280______________________________________ As can be seen from the above, heating the resin instead of the bolt, tension does not increase, but actually decreases. This can be explained by the fact that since the resin is warmer than the bolt, the bolt begins to expand as it is heated by the resin and is pushed out of the curing resin, thereby losing its tension.	An improved method of installing tensional anchor bolts or cable bolts into a geological or man made formation by preheating anchor bolts or cables prior to inserting them into a borehole, mixing the bonding material within the borehole by rotating the bolt and allowing curing of the bonding material prior to the cooling of the bolt, thereby placing the bolt under tension and the formation into compression, is provided.	4
TECHNICAL FIELD Embodiments of the invention relate to carabiners, to methods of manufacturing carabiners, and to methods of using carabiners. BACKGROUND Carabiners are ring-like devices that have a gate that can be opened and closed to allow, for example, a bight of rope to be passed through the gate such that the rope extends through the carabiner without having to thread an end of the rope through the carabiner. Carabiners are used in various applications. Carabiners are often used in outdoor recreational activities such as rock climbing, mountaineering, and sailing. Carabiners are also employed, however, in non-recreational applications such as, for example, rescue operations and military applications. Generally, a carabiner has a C-shaped ring body having a first end and a second end with an opening therebetween. A gate is pivotally attached to one end of the ring body and extends across the opening in the ring body to the other end of the ring body, such that the gate may be selectively opened to allow articles to pass through the opening between the ends of the ring body, or closed to prevent articles from passing through the opening between the ends of the ring body. The gate may be biased to the closed position using, for example, a spring positioned and configured to urge the gate to the closed position. To avoid inadvertent opening of the gate of a carabiner, it is known in the art to provide a locking sleeve on the gate. The locking sleeve may be movable between a locked position and an unlocked position. In the locked position, the locking sleeve prevents the gate from moving from the closed position to the open position, but allows the gate to move from the closed position to the open position when the locking sleeve is in the unlocked position. In some carabiners, the locking sleeve is threaded onto the gate, such that the locking sleeve is rotated in a first direction about the gate by a user to move the locking sleeve into the locked position, and rotated in an opposite, second direction about the gate by the user to move the locking sleeve into the unlocked position. In other carabiners, the locking sleeve is configured to slide in a longitudinal direction relative to the gate between the locked and unlocked positions. In such embodiments, the locking sleeve may be biased to the locked position using, for example, a spring positioned and configured to urge the locking sleeve to the locked position. Examples of carabiners that include locking sleeves are disclosed in, for example, U.S. patent application Ser. No. 11/291,493, filed Dec. 1, 2005 (published Jun. 29, 2006 as United States Patent Application Publication No. U.S. 2006/0137151 A1); U.S. patent application Ser. No. 11/827,380, filed Jul. 10, 2007 (published Jan. 31, 2008 as United States Patent Application Publication No. U.S. 2008/0022497 A1); and U.S. Pat. No. 6,588,076 to Choate, which issued Jul. 8, 2003. BRIEF SUMMARY In some embodiments, the present invention includes carabiners having a gate that is pivotally attached to a first end of a body and movable between a closed position and an open position, and a locking sleeve that is movable between a locked position and a retainable unlocked position. In the closed position, the gate extends from the first end to a second end of the body. The locking member is biased to the locked position, and is configured to prevent the gate from opening when the gate is in the closed position and the locking member is in the locked position, and to allow the gate to open when the gate is in the closed position and the locking member is in the retainable unlocked position. The locking sleeve is configured to move out of the retainable unlocked position when the gate is pivoted relative to the body of the carabiner beyond a threshold angle as the gate is opened. In additional embodiments, the present invention includes methods of manufacturing carabiners. A gate is pivotally attached to a first end of a body of a carabiner, and the gate is configured to pivot relative to the body between a closed position and an open position. A locking member is attached to at least one of the gate and the body of the carabiner. The locking member is configured to move relative to the gate between a locked position and a retainable unlocked position, and is biased to the locked position. The locking member is further configured to prevent the gate from opening when the gate is in the closed position and the locking member is in the locked position, and to allow the gate to open when the gate is in the closed position and the locking member is in the retainable unlocked position. The locking sleeve is configured to move out of the retainable unlocked position when the gate is pivoted relative to the body of the carabiner beyond a threshold angle upon opening the gate. In yet further embodiments, the present invention includes methods of using a carabiner in which a locking sleeve of a carabiner is positioned in a retainable unlocked position. A gate of the carabiner is opened while the carabiner is in the retainable unlocked position, the locking sleeve of the carabiner is moved out of the retainable unlocked position by pivoting the gate relative to a body of the carabiner beyond a threshold angle, and the locking sleeve is allowed to at least substantially automatically move to a locked position as the gate is moved to a closed position. These features, advantages, and aspects of particular embodiments of the present invention will be apparent to those in the art from a consideration of the detailed description set forth below when considered together with the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, the advantages of this invention may be more readily ascertained from the description of embodiments of the invention when read in conjunction with the accompanying drawings, in which: FIGS. 1A through 1C illustrate an embodiment of a carabiner of the present invention and shows a gate of the carabiner in a closed position, and a locking sleeve of the carabiner in a retainable unlocked position; FIG. 1A is a side plan view of the carabiner; FIG. 1B is an end plan view of the carabiner; FIG. 1C is a plan view of a side of the carabiner opposite that shown in FIG. 1A ; FIGS. 2A through 2C illustrate the carabiner of FIGS. 1A through 1C , and shows the gate of the carabiner in an open position; FIG. 2A is a side plan view of the carabiner; FIG. 2B is an end plan view of the carabiner; FIG. 2C is a plan view of a side of the carabiner opposite that shown in FIG. 2A ; FIGS. 3A through 3C illustrate the carabiner of FIGS. 1A through 1C and 2 A through 2 C, and show the gate of the carabiner in a closed position, and the locking sleeve of the carabiner in a locked position; FIG. 3A is a side plan view of the carabiner; FIG. 3B is an end plan view of the carabiner; FIG. 3C is a plan view of a side of the carabiner opposite that shown in FIG. 3A ; FIG. 4 is an exploded view of the gate, the locking sleeve, and a spring member of the carabiner shown in FIGS. 1A through 1C , 2 A through 2 C, and 3 A through 3 C; FIGS. 5A through 5C illustrate another embodiment of a carabiner of the present invention; FIG. 5A is a perspective view of the carabiner and shows a gate of the carabiner in a closed position and a locking sleeve of the carabiner in a retainable unlocked position; FIG. 5B is a side plan view of the carabiner showing the gate in an open position and the locking sleeve moving out from the retainable unlocked position; and FIG. 5C is a side plan view like that of FIG. 5B and shows the gate in the closed position and the locking sleeve in a locked position. FIGS. 6A through 6C illustrate another embodiment of a carabiner of the present invention; FIG. 6A is a perspective view of the carabiner and shows a gate of the carabiner in a closed position and a locking sleeve of the carabiner in a retainable unlocked position; FIG. 6B is a side plan view of the carabiner showing the gate in an open position and the locking sleeve moving out from the retainable unlocked position; and FIG. 6C is a side plan view like that of FIG. 6B and shows the gate in the closed position and the locking sleeve in a locked position. DETAILED DESCRIPTION OF THE INVENTION The illustrations presented herein are not meant to be actual views of any particular material, apparatus, system, or method, but are merely idealized representations which are employed to describe the present invention. Additionally, elements common between figures may retain the same numerical designation. The present invention, in a number of embodiments, includes carabiners having a locking sleeve that can be retained in an unlocked position without application of force to the locking sleeve by a user, but that are biased to a locked position such that, as a user urges the locking sleeve out of the unlocked position, the carabiner substantially automatically moves to the locked position. FIGS. 1A through 1C , 2 A through 2 C, and 3 A through 3 C illustrate an embodiment of a carabiner 100 of the present invention. As discussed in further detail below, the carabiner 100 has a generally C-shaped body 102 , a gate 110 that is movable between a closed position and an open position, and a locking sleeve 120 that is movable between a locked position and a retainable unlocked position. FIGS. 1A through 1C illustrate the carabiner 100 with the gate 110 in the closed position and the locking sleeve 120 retained in a retainable unlocked position. FIGS. 2A through 2C illustrate the carabiner 100 with the gate 110 in an open position and the locking sleeve 120 in the process of being urged out from the retainable unlocked position. FIGS. 3A through 3C illustrate the carabiner 100 with the gate 110 in the closed position and the locking sleeve 120 in the locked position. Referring to FIG. 1A , the carabiner 100 includes a generally C-shaped body 102 having a first end 104 and a second end 106 that are separated from one another by an opening that is not visible in FIGS. 1A through 1C , as the opening is closed by the gate 110 in FIGS. 1A through 1C . The generally C-shaped body 102 may be formed from and comprise a metal or metal alloy such as, for example, an aluminum-based alloy, an iron-based alloy, a nickel-based alloy, a cobalt-based alloy, a magnesium-based alloy, a titanium-based alloy, etc. In other embodiments, the generally C-shaped body 102 may be formed from and comprise a polymer material, or a composite material such as, for example, a fiber or whisker (e.g., carbon fiber) reinforced polymer (e.g., epoxy) or metal alloy material. The first end 104 of the body 102 is configured for attachment to an end of the gate 110 (the lower end from the perspectives of FIGS. 1A through 1C ), and the second end 106 of the body 102 is configured to interact with another, opposite end of the gate 110 (the upper end from the perspectives of FIGS. 1A through 1C ). The lower end of the gate 110 may be pivotally attached to the first end 104 of the body 102 using, for example, a pin member 130 (e.g., a rivet) that extends through the first end 104 of the body 102 and through the lower end of the gate 110 . As shown in FIG. 1A , the pin member 130 may include a head 132 that projects laterally outward from the first end 104 of the body 102 on one side thereof (e.g., the side shown in FIG. 1A ). The pin member 130 may be substantially flush with the surface of the first end 104 of the body 102 on an opposite side of the body 102 (e.g., on the side shown in FIG. 1C ). The head 132 of the pin member 130 may interact with features of the locking sleeve 120 , as discussed in further detail herein below. The second end 106 of the body 102 may include what is referred to in the art as a “nose” 108 that is configured to be received within a receptacle 112 ( FIG. 4 ) formed in the upper end of the gate 110 when the gate 110 is in the closed position. An aperture 128 is formed in the upper end of the locking sleeve 120 to allow the nose 108 to be received into the receptacle 112 of the gate 110 as the gate 110 moves from the open position into the closed position, but the upper end of the gate 110 is configured to preclude the nose 108 from passing through the upper end of the gate 110 . For example, the receptacle 112 in the gate 110 does not extend entirely through the gate 110 . As a result, the gate 110 is only capable of pivoting inward into the area enclosed by the C-shaped body 102 and is precluded from pivoting outward relative to the C-shaped body 102 . As shown in FIG. 1A , the locking sleeve 120 is carried by, and positioned concentrically about, the gate 110 . The locking sleeve 120 and the gate 110 are configured such that the locking sleeve 120 can rotate circumferentially about the gate 110 , and such that the locking sleeve 120 can slide longitudinally along the gate 110 . FIG. 4 is an exploded view of the gate 110 , the locking sleeve 120 , and a spring member 138 that is disposed between the gate 110 and the locking sleeve 120 . The spring member 138 is hidden from view in FIGS. 1A through 1C . In the embodiment shown in FIG. 4 , the spring member 138 is a torsion spring that acts on both the gate 110 and the locking sleeve 120 in such a manner as to bias the locking sleeve 120 toward the first end 104 of the body 102 (the downward direction in the perspectives of FIGS. 1A through 1C ), and also to rotationally bias the locking sleeve 120 in a counter-clockwise rotational direction about the gate 110 (when looking at the end surfaces of the gate 110 and locking sleeve 120 proximate the second end 106 of the body 102 ). Referring again to FIG. 1A , in the absence of an applied external force, the spring member 138 forces the locking sleeve 120 toward the first end 104 of the body 102 (in the downward direction in the perspectives of FIGS. 1A through 1C ) to cause a lower surface 121 of the locking sleeve 120 to abut against the head 132 of the pin member 130 , which prevents the locking sleeve 120 from further movement toward the first end 104 of the body 102 . A user, however, can apply an external force to the locking sleeve 120 to cause the locking sleeve 120 to slide toward the second end 106 of the body 102 (in the upward direction in the perspectives of FIGS. 1A through 1C ). Also, in the absence of an applied external force, the spring member 138 ( FIG. 4 ) forces the locking sleeve 120 to rotate in the counter-clockwise direction (when looking at the end surfaces of the gate 110 and locking sleeve 120 proximate the second end 106 of the body 102 ). The lower surface 121 of the locking sleeve 120 is configured with a profile that includes features configured to interact with the head 132 of the pin member 130 in such a manner as to preclude rotation of the locking sleeve 120 about the gate 110 in the absence of an applied external force. For example, the lower surface 121 of the locking sleeve 120 includes a first notch 122 (e.g., an indentation) shown in FIG. 1A . When the locking sleeve 120 is in the retainable unlocked position shown in FIGS. 1A through 1C , the head 132 of the pin member 130 is disposed within the first notch 122 . As the spring member 138 forces the lower surface 121 within the notch 122 of the locking sleeve 120 against the head 132 of the pin member 130 , the notch 122 prevents the locking sleeve 120 from rotating in the counter-clockwise direction responsive to the rotational forces applied to the locking sleeve 120 by the spring member 138 . If, however, the locking sleeve 120 is moved relative to the gate 110 such that the head 132 of the pin member 130 is not disposed within the first notch 122 , the spring member 138 may urge the locking sleeve 120 to rotate in the counter-clockwise direction about the gate 110 until the head 132 of the pin member 130 impinges on another feature of the lower surface 121 of the locking sleeve 120 (e.g., a second notch 124 shown in FIG. 3A ) that precludes further rotation of the locking sleeve 120 in the counter-clockwise direction. Referring to FIG. 1B , an aperture 128 is provided in the end of the locking sleeve 120 proximate the second end 106 of the body 102 (the upper end in the perspectives of FIGS. 1A through 1C ). The aperture 128 is configured to allow the nose 108 at the second end 106 of the body 102 to pass therethrough when the aperture 128 is aligned with the nose 108 as shown in FIG. 1B . The aperture 128 is aligned with the nose 108 when the locking sleeve 120 is in the retainable unlocked position shown in FIGS. 1A through 1C . Thus, when the locking sleeve 120 is in the retainable unlocked position shown in FIGS. 1A through 1C , a user of the carabiner 100 can pull the locking sleeve 120 and the gate 110 into an interior area enclosed by the body 102 of the carabiner 100 . In other words, a user can move the gate 110 into an open position shown in FIGS. 2A through 2C when the locking sleeve 120 is in the retainable unlocked position shown in FIGS. 1A through 1C . Referring to FIGS. 2A through 2C , as long as the locking sleeve 120 is not moved out of the retainable unlocked position shown in FIGS. 1A through 1C relative to the gate 110 (i.e., as long as the head 132 of the pin member 130 remains disposed within the first notch 122 in the surface 121 of the locking sleeve 120 ), the gate 110 can be freely moved back and forth between the closed position shown in FIGS. 1A through 1C and the open position shown in FIGS. 2A through 2C . In some embodiments, the carabiner 100 may be configured such that, as the gate 110 is moved into the open position shown in FIGS. 2A through 2C , the head 132 of the pin member 130 may be urged out from the notch 122 in the surface 121 of the locking sleeve 120 if the gate 110 (and locking sleeve 120 ) is pivoted to or beyond a threshold angle relative to the body 102 of the carabiner 100 . By way of example and not limitation, the locking sleeve 120 and the first end 104 of the body 102 may be sized and configured such that, as the gate 110 (and locking sleeve 120 ) is pivoted to a threshold angle relative to the body 102 of the carabiner 100 , as shown in FIG. 2A , the lower surface 121 of the locking sleeve 120 will abut against the body 102 proximate the first end 104 thereof at a pinch point 140 . If the gate 110 (and locking sleeve 120 ) is further pivoted inward beyond the threshold angle relative to the body 102 , the contact between the body 102 and the locking sleeve 120 at the pinch point 140 will cause the locking sleeve 120 to slide longitudinally along the gate 110 away from the pin member 130 such that the head 132 of the pin member 130 is urged out from the first notch 122 in the lower surface 121 of the locking sleeve 120 . After the head 132 of the pin member 130 is urged out from the first notch 122 in the lower surface 121 of the locking sleeve 120 , the spring member 138 ( FIG. 4 ) between the gate 110 and the locking sleeve 120 will prevent the head 132 of the pin member 130 from returning to the notch 122 in the absence of an applied external force, and will urge the locking sleeve 120 to rotate to the locked position shown in FIGS. 3A through 3C . As shown in FIG. 2C , however, when the gate 110 (and the locking sleeve 120 ) is in the open position shown in FIGS. 2A through 2C , a projection 126 ( FIG. 1C ) of the locking sleeve 120 that extends downward (from the perspective of FIG. 2C ) past the pin member 130 and laterally beside the first end 104 of the body 102 prevents the locking sleeve 120 from rotating about the gate 110 responsive to the forces applied by the spring member 138 ( FIG. 4 ) until the gate 110 (and the locking sleeve 120 ) has pivoted back toward the closed position to an extent that the nose 108 of the second end 106 of the body 102 has passed at least partially through the aperture 128 in the end of the locking sleeve 120 proximate the second end 106 of the body 102 . Stated another way, the projection 126 may be sized and configured to pass over the body 102 only after the gate 110 (and the locking sleeve 120 ) has pivoted back toward the closed position and the nose 108 has passed at least partially through the aperture 128 . Thus, the projection 126 maintains the aperture 128 in the locking sleeve 120 in alignment with the nose 108 until the nose 108 has passed at least partially through the aperture 128 . If the aperture 128 were not maintained in alignment with the nose 108 until the nose 128 had passed at least partially through the aperture 128 , the spring member 138 could cause the locking sleeve 120 to rotate relative to the gate 110 such that the aperture 128 were not aligned with the nose 108 , in which case interference between the nose 108 and the end of the locking sleeve 120 proximate the second end 106 of the body 102 would prevent the gate 110 (and the locking sleeve 120 ) from returning to the closed position. As the projection 126 clears the body 102 , the nose 108 will be partially disposed within the aperture 128 . Interference between the nose 108 and the surfaces of the locking sleeve 120 within the aperture 128 , however, will prevent the locking sleeve 120 from further rotation about the gate 110 response to the forces acting on the locking sleeve 120 until the nose 108 has passed entirely through the aperture 128 in the locking sleeve 120 . As the gate 110 moves from the open position shown in FIGS. 2A through 2C into the closed position shown in FIGS. 3A through 3C , the nose 108 of the second end 106 of the body 102 will pass entirely through the aperture 128 in the locking sleeve 120 , at which point, the spring member 138 ( FIG. 4 ) between the gate 110 and the locking sleeve 120 will cause the locking sleeve 120 to further rotate in the counter-clockwise direction about the gate 110 until the head 132 of the pin member 130 is forced into a second notch 124 in the lower surface 121 of the locking sleeve 120 . The second notch 124 may be disposed adjacent the projection 126 such that the projection 126 prevents further rotation of the locking sleeve 120 about the gate 110 in the counter-clockwise direction. When the head 132 of the pin member 130 is disposed within the second notch 124 , the locking sleeve 120 is in a locked position in which the aperture 128 is not aligned with the nose 108 and the end of the locking sleeve 120 proximate the second end 106 of the body 102 locks the gate 110 to the nose 108 in the closed position. Thus, when the gate 110 is closed and the locking sleeve 120 is in the locked position, as shown in FIGS. 3A through 3C , the locking sleeve 120 prevents the gate 110 from inadvertently being opened. To unlock the locking sleeve 120 and open the gate 110 , a user may apply a force to the locking sleeve 120 to move the locking sleeve 120 out of the locked position shown in FIGS. 3A through 3C and to rotate the locking sleeve 120 about the gate 110 until the aperture 128 in the locking sleeve 120 is aligned with the nose 108 , at which point the gate 110 may be opened. In particular, a user may apply a force to the locking sleeve 120 to cause the locking sleeve 120 to slide longitudinally along the gate 110 toward the second end 106 of the body 102 , and to cause the locking sleeve 120 to rotate in the clockwise direction about the gate 110 in such a manner as to cause the head 132 of the pin member 130 to be dislodged out of the second notch 124 , to align the aperture 128 with the nose 108 , and to open the gate 110 . Optionally, a user may move the locking sleeve 120 from the locked position shown in FIGS. 3A through 3C to the retainable unlocked position shown in FIGS. 1A through 1C , in which the head 132 of the pin member 130 is lodged within the first notch 122 in the locking sleeve 120 . If the user lodges the head 132 of the pin member 130 within the first notch 122 in the locking sleeve 120 before or after moving the gate 110 to the open position, the locking sleeve 120 may be freely opened and closed, as previously described herein, without causing the locking sleeve 120 to move into the locked position (shown in FIGS. 3A through 3C ) until the locking sleeve 120 is pivoted relative to the body 102 beyond the threshold angle. If, however, the user does not lodge the head 132 of the pin member 130 within the first notch 122 in the locking sleeve 120 before or after moving the gate 110 to the open position, the locking sleeve 120 will return to the locked position shown in FIGS. 3A through 3C when the gate 110 returns to the closed position after the user opens the gate 110 . FIGS. 5A through 5C illustrate another embodiment of a carabiner 200 of the present invention. The carabiner 200 is generally similar to the carabiner 100 previously described herein, and has a generally C-shaped body 102 and a gate 110 substantially similar to those of the carabiner 100 . The carabiner 200 also includes a locking sleeve 220 that is movable between a locked position and a retainable unlocked position. In the carabiner 200 , however, the locking sleeve 220 is biased toward the second end 106 of the body 102 , instead of toward the first end 104 of the body 102 , as is the locking sleeve 220 of the carabiner 100 . FIG. 5A illustrates the carabiner 200 with the gate 110 in the closed position and the locking sleeve 220 retained in a retainable unlocked position. FIG. 5B illustrates the carabiner 200 with the gate 110 in an open position and the locking sleeve 220 in the process of being urged out from the retainable unlocked position. FIG. 5C illustrates the carabiner 200 with the gate 110 in the closed position and the locking sleeve 220 in the locked position. Referring to FIG. 5A , the lower end of the gate 110 may be pivotally attached to the first end 104 of the body 102 using, for example, a pin member (e.g., a rivet) (like the pin member 130 of FIGS. 1A through 1C ) that extends through the first end 104 of the body 102 and through the lower end of the gate 110 . As shown in FIG. 5A , the pin member may include a head 132 that projects laterally outward from the first end 104 of the body 102 on one side thereof (e.g., the side shown in FIG. 5A ). The pin member may be substantially flush with the surface of the first end 104 of the body 102 on an opposite side of the body 102 . The head 132 of the pin member may interact with features of the locking sleeve 220 , as discussed in further detail herein below. The second end 106 of the body 102 may include a nose 108 that is configured to be received within a receptacle (not visible in FIGS. 5A through 5C ) (like the receptacle 112 shown in FIG. 4 ) formed in the upper end of the gate 110 when the gate 110 is in the closed position. An aperture 228 is formed in the upper end of the locking sleeve 220 to allow the nose 108 to be received into the receptacle of the gate 110 as the gate 110 moves from the open position into the closed position, but the upper end of the gate 110 is configured to preclude the nose 108 from passing through the upper end of the gate 110 . The locking sleeve 220 is carried by, and positioned concentrically about, the gate 110 . The locking sleeve 220 and the gate 110 are configured such that the locking sleeve 220 can rotate circumferentially about the gate 110 , and such that the locking sleeve 220 can slide longitudinally along the gate 110 . A spring member (like the spring member 138 of FIG. 4 ) is disposed between the gate 110 and the locking sleeve 220 . The spring member is hidden from view in FIGS. 5A through 5C . The spring member may comprise a torsion spring that acts on both the gate 110 and the locking sleeve 220 in such a manner as to bias the locking sleeve 220 toward the second end 106 of the body 102 (the upward direction in the perspectives of FIGS. 5A through 5C ), and also to rotationally bias the locking sleeve 220 in a counter-clockwise rotational direction about the gate 110 (when looking at the end surfaces of the gate 110 and locking sleeve 220 proximate the second end 106 of the body 102 ). With continued reference to FIG. 5A , an elongated aperture 221 (e.g., a slot) is formed through the end of the locking sleeve 220 proximate the first end 104 of the body 102 , and the locking sleeve 220 is assembled with the gate 110 and the pin member such that the head 132 of the pin member is disposed within the elongated aperture 221 . Thus, in the absence of an applied external force, the spring member forces the locking sleeve 220 toward the second end 106 of the body 102 (in the upward direction in the perspectives of FIGS. 5A through 5C ) to cause a lower surface 227 of the locking sleeve 220 within the elongated aperture 221 to abut against the head 132 of the pin member, which prevents the locking sleeve 220 from further movement toward the second end 104 of the body 102 . A user, however, can apply an external force to the locking sleeve 220 to cause the locking sleeve 220 to slide toward the first end 104 of the body 102 (in the downward direction in the perspectives of FIGS. 5A through 5C ). Also, in the absence of an applied external force, the spring member forces the locking sleeve 220 to rotate in the counter-clockwise direction (when looking at the end surfaces of the gate 110 and locking sleeve 220 proximate the second end 106 of the body 102 ). The lower surface 227 of the locking sleeve 220 is configured with a profile that includes features configured to interact with the head 132 of the pin member in such a manner as to preclude rotation of the locking sleeve 220 about the gate 110 in the absence of an applied external force. For example, the lower surface 227 of the locking sleeve 220 within the elongated aperture 221 includes a first notch 222 (e.g., an indentation) shown in FIGS. 5A and 5B . When the locking sleeve 220 is in the retainable unlocked position shown in FIG. 5A , the head 132 of the pin member is disposed within the first notch 222 . As the spring member forces the lower surface 227 of the locking sleeve 220 within the notch 222 against the head 132 of the pin member, the notch 222 prevents the locking sleeve 220 from rotating in the counter-clockwise direction responsive to the rotational forces applied to the locking sleeve 220 by the spring member. If, however, the locking sleeve 220 is moved relative to the gate 110 such that the head 132 of the pin member is not disposed within the first notch 222 , the spring member may urge the locking sleeve 220 to rotate in the counter-clockwise direction about the gate 110 until the head 132 of the pin member impinges on another feature of the lower surface 227 of the locking sleeve 220 within the elongated aperture 221 (e.g., a second notch 224 shown in FIGS. 5A through 5C ) that precludes further rotation of the locking sleeve 220 in the counter-clockwise direction. Referring to FIG. 5B , an aperture 228 is provided in the end of the locking sleeve 220 proximate the second end 106 of the body 102 (the upper end in the perspectives of FIGS. 5A through 5C ). The aperture 228 is configured to allow the nose 108 at the second end 106 of the body 102 to pass therethrough when the aperture 228 is aligned with the nose 108 , as shown in FIG. 5A . The aperture 228 is aligned with the nose 108 when the locking sleeve 220 is in the retainable unlocked position shown in FIG. 5A . Thus, when the locking sleeve 220 is in the retainable unlocked position shown in FIG. 5A , a user of the carabiner 200 can pull the locking sleeve 220 and the gate 110 into an interior area enclosed by the body 102 of the carabiner 200 . In other words, a user can move the gate 110 into the open position shown in FIG. 5B when the locking sleeve 220 is in the retainable unlocked position shown in FIG. 5A . Referring to FIG. 5B , as long as the locking sleeve 220 is not moved out of the retainable unlocked position shown in FIG. 5A relative to the gate 110 (i.e., as long as the head 132 of the pin member 130 remains disposed within the first notch 222 within the aperture 221 of the locking sleeve 220 ), the gate 110 can be freely moved back and forth between the closed position shown in FIG. 5A and an open position as shown in FIG. 5B . In some embodiments, the carabiner 200 may be configured such that, as the gate 110 is moved into the open position shown in FIG. 5B , the head 132 of the pin member may be urged out from the notch 222 in the lower surface 227 of the locking sleeve 220 within the elongated aperture 221 if the gate 110 (and the locking sleeve 220 ) is pivoted to or beyond a threshold angle relative to the body 102 of the carabiner 200 . By way of example and not limitation, the locking sleeve 220 and the body 102 may be sized and configured such that, as the gate 110 and locking sleeve 220 are pivoted to a threshold angle relative to the body 102 of the carabiner 200 , as shown in FIG. 5B , an upper surface 250 of the locking sleeve 220 will abut against the body 102 proximate at a pinch point 240 . If the gate 110 and the locking sleeve 220 are further pivoted inward beyond the threshold angle relative to the body 102 , the contact between the body 102 and the locking sleeve 220 at the pinch point 240 will cause the locking sleeve 220 to slide longitudinally along the gate 110 toward the first end 104 of the body 102 and the pin member such that the head 132 of the pin member is urged out from the first notch 222 within the elongated aperture 221 of the locking sleeve 220 . After the head 132 of the pin member is urged out from the first notch 222 within the elongated aperture 221 of the locking sleeve 220 , the spring member between the gate 110 and the locking sleeve 220 will prevent the head 132 of the pin member from returning to the notch 222 in the absence of an applied external force, and will urge the locking sleeve 220 to rotate to the locked position shown in FIG. 5C . When the gate 110 (and the locking sleeve 220 ) is in the open position shown in FIG. 5B , a projection 226 of the locking sleeve 220 that extends downward (from the perspective of FIG. 5B ) past the pin member 130 and laterally beside the first end 104 of the body 102 , prevents the locking sleeve 220 from rotating about the gate 110 responsive to the forces applied by the spring member until the gate 110 (and the locking sleeve 220 ) has pivoted back toward the closed position to an extent that the nose 108 of the second end 106 of the body 102 has passed at least partially through the aperture 228 in the end of the locking sleeve 220 proximate the second end 106 of the body 102 . Stated another way, the projection 226 may be sized and configured to pass over the body 102 only after the gate 110 (and the locking sleeve 220 ) has pivoted back toward the closed position and the nose 108 has passed at least partially through the aperture 228 in the locking sleeve 220 . Thus, the projection 226 maintains the aperture 228 in the locking sleeve 220 in alignment with the nose 108 until the nose 108 has passed at least partially through the aperture 228 . If the aperture 228 were not maintained in alignment with the nose 108 until the nose 108 had passed at least partially through the aperture 228 , the spring member could cause the locking sleeve 220 to rotate relative to the gate 110 such that the aperture 228 were not aligned with the nose 108 , in which case interference between the nose 108 and the end of the locking sleeve 220 proximate the second end 106 of the body 102 would prevent the gate 110 (and the locking sleeve 220 ) from returning to the closed position. As the projection 226 clears the body 102 , the nose 108 will be partially disposed within the aperture 228 . Interference between the nose 108 and the surfaces of the locking sleeve 220 within the aperture 228 , however, will prevent the locking sleeve 220 from further rotation about the gate 110 response to the forces acting on the locking sleeve 220 until the nose 108 has passed entirely through the aperture 228 in the locking sleeve 220 and into the receptacle in the gate 110 . As the gate 110 moves from the open position shown in FIG. 5B into the closed position shown in FIG. 5C , the nose 108 of the second end 106 of the body 102 will pass entirely through the aperture 228 in the locking sleeve 220 , at which point, the spring member between the gate 110 and the locking sleeve 220 will cause the locking sleeve 220 to further rotate in the counter-clockwise direction about the gate 110 until the head 132 of the pin member is forced into a second notch 224 in the lower surface 227 of the locking sleeve 220 within the elongated aperture 221 . The end of the elongated aperture 221 adjacent the second notch 224 prevents further rotation of the locking sleeve 220 about the gate 110 in the counter-clockwise direction. When the head 132 of the pin member is disposed within the second notch 224 , the locking sleeve 220 is in a locked position in which the aperture 228 is not aligned with the nose 108 and the end of the locking sleeve 220 proximate the second end 106 of the body 102 locks the gate 110 to the nose 108 in the closed position. Thus, when the gate 110 is closed and the locking sleeve 220 is in the locked position, as shown in FIG. 5C , the locking sleeve 220 prevents the gate 110 from inadvertently being opened. To unlock the locking sleeve 220 and open the gate 110 , a user may apply a force to the locking sleeve 220 to move the locking sleeve 220 out of the locked position shown in FIG. 5C and to rotate the locking sleeve 220 about the gate 110 until the aperture 228 in the locking sleeve 220 is aligned with the nose 108 , at which point the gate 110 may be opened. In particular, a user may apply a force to the locking sleeve 220 to cause the locking sleeve 220 to slide longitudinally along the gate 110 toward the first end 104 of the body 102 , and to cause the locking sleeve 220 to rotate in the clockwise direction about the gate 110 in such a manner as to cause the head 132 of the pin member to be dislodged out of the second notch 224 , to align the aperture 228 with the nose 108 , and to open the gate 110 . Optionally, a user may move the locking sleeve 220 from the locked position shown in FIG. 5C to the retainable unlocked position shown in FIG. 5A , in which the head 132 of the pin member is lodged within the first notch 222 in the locking sleeve 220 . If the user lodges the head 132 of the pin member within the first notch 222 in the locking sleeve 220 before or after moving the gate 110 to the open position, the locking sleeve 220 may be freely opened and closed, as previously described herein, without causing the locking sleeve 220 to move into the locked position (shown in FIG. 5C ) until the locking sleeve 220 is pivoted relative to the body 102 beyond the threshold angle. If, however, the user does not lodge the head 132 of the pin member within the first notch 222 in the locking sleeve 220 before or after moving the gate 110 to the open position, the locking sleeve 220 will return to the locked position shown in FIG. 5C when the gate 110 returns to the closed position after the user opens the gate 110 . FIGS. 6A through 6C illustrate another embodiment of a carabiner 300 of the present invention. The carabiner 300 is generally similar to the carabiner 100 previously described with reference to FIGS. 1A-1C , and has a generally C-shaped body 102 and a gate 110 like those of the carabiner 100 . The carabiner 300 also includes a locking sleeve 320 that is movable between a locked position and a retainable unlocked position. Like the locking sleeve 120 of the carabiner 100 , the locking sleeve 320 of the carabiner 300 is biased toward the first end 104 of the body 102 . FIG. 6A illustrates the carabiner 300 with the gate 110 in the closed position and the locking sleeve 320 retained in a retainable unlocked position. FIG. 6B illustrates the carabiner 300 with the gate 110 in an open position and the locking sleeve 320 in the process of being urged out from the retainable unlocked position. FIG. 6C illustrates the carabiner 300 with the gate 110 in the closed position and the locking sleeve 320 in the locked position. Referring to FIG. 6A , the lower end of the gate 110 may be pivotally attached to the first end 104 of the body 102 using, for example, a pin member (e.g., a rivet) (like the pin member 130 of FIGS. 1A through 1C ) that extends through the first end 104 of the body 102 and through the lower end of the gate 110 . The pin member may include a head 132 that projects laterally outward from the first end 104 of the body 102 on one side thereof (e.g., the side shown in FIG. 6A ). The head 132 of the pin member may interact with features of the locking sleeve 320 , as discussed in further detail herein below. The second end 106 of the body 102 may include a nose 108 that is configured to be received within a receptacle (not visible in FIGS. 6A through 6C ) (like the receptacle 112 shown in FIG. 4 ) formed in the upper end of the gate 110 when the gate 110 is in the closed position. An aperture 328 is formed in the upper end of the locking sleeve 320 to allow the nose 108 to be received into the receptacle of the gate 110 as the gate 110 moves from the open position into the closed position, but the upper end of the gate 110 may by configured to preclude the nose 108 from passing entirely through the upper end of the gate 110 . The locking sleeve 320 is carried by, and positioned concentrically about, the gate 110 . The locking sleeve 320 and the gate 110 are configured such that the locking sleeve 320 can rotate circumferentially about the gate 110 , and such that the locking sleeve 320 can slide longitudinally along the gate 110 . A spring member (like the spring member 138 of FIG. 4 ) is disposed between the gate 110 and the locking sleeve 320 . The spring member is hidden from view in FIGS. 6A through 6C . The spring member may comprise a torsion spring that acts on both the gate 110 and the locking sleeve 320 in a similar manner as does the spring member 138 of carabiner 100 , so as to bias the locking sleeve 320 toward the first end 104 of the body 102 (the downward direction from the perspectives of FIGS. 6A through 6C ), and also to rotationally bias the locking sleeve 320 in a counter-clockwise rotational direction about the gate 110 (when looking at the end surfaces of the gate 110 and locking sleeve 320 proximate the second end 106 of the body 102 ). With continued reference to FIG. 6A , an elongated aperture 321 (e.g., a slot) is formed through the locking sleeve 320 near the end thereof proximate the first end 104 of the body 102 , and the locking sleeve 320 is assembled with the gate 110 and the pin member such that the head 132 of the pin member is disposed within the elongated aperture 321 . Thus, in the absence of an applied external force, the spring member forces the locking sleeve 320 toward the first end 104 of the body 102 (in the downward direction in the perspectives of FIGS. 6A through 6C ) to cause an upper surface 327 of the locking sleeve 320 within the elongated aperture 321 to abut against the head 132 of the pin member, which prevents the locking sleeve 320 from further movement toward the second end 104 of the body 102 . A user, however, can apply an external force to the locking sleeve 320 to cause the locking sleeve 320 to slide toward the second end 106 of the body 102 (in the upward direction in the perspectives of FIGS. 6A through 6C ). Also, in the absence of an applied external force, the spring member forces the locking sleeve 320 to rotate in the counter-clockwise direction (when looking at the end surfaces of the gate 110 and locking sleeve 320 proximate the second end 106 of the body 102 ). The upper surface 327 of the locking sleeve 320 is configured with a profile that includes features configured to interact with the head 132 of the pin member in such a manner as to preclude rotation of the locking sleeve 320 about the gate 110 in the absence of an applied external force. For example, the upper surface 327 of the locking sleeve 320 within the elongated aperture 321 includes a first notch 322 (e.g., an indentation) shown in FIGS. 6A and 6B . When the locking sleeve 320 is in the retainable unlocked position shown in FIG. 5A , the head 132 of the pin member is disposed within the first notch 322 . As the spring member forces the upper surface 327 of the locking sleeve 320 within the notch 322 against the head 132 of the pin member, the notch 322 prevents the locking sleeve 320 from rotating in the counter-clockwise direction responsive to the rotational forces applied to the locking sleeve 320 by the spring member. If, however, the locking sleeve 320 is moved relative to the gate 110 such that the head 132 of the pin member is not disposed within the first notch 322 , the spring member may urge the locking sleeve 320 to rotate in the counter-clockwise direction about the gate 110 until the head 132 of the pin member impinges on another feature of the upper surface 327 of the locking sleeve 320 within the elongated aperture 321 (e.g., a second notch 324 shown in FIGS. 6A and 6C ) that precludes further rotation of the locking sleeve 320 in the counter-clockwise direction. Referring to FIG. 6B , an aperture 328 is provided in the end of the locking sleeve 320 proximate the second end 106 of the body 102 (the upper end in the perspectives of FIGS. 6A through 6C ). The aperture 328 is configured to allow the nose 108 at the second end 106 of the body 102 to pass therethrough when the aperture 328 is aligned with the nose 108 , as shown in FIG. 6A . The aperture 328 is aligned with the nose 108 when the locking sleeve 320 is in the retainable unlocked position shown in FIG. 6A . Thus, when the locking sleeve 320 is in the retainable unlocked position shown in FIG. 6A , a user of the carabiner 300 can move the gate 110 into the open position shown in FIG. 6B . Referring to FIG. 6B , as long as the locking sleeve 320 is not moved out of the retainable unlocked position shown in FIG. 6A relative to the gate 110 (i.e., as long as the head 132 of the pin member 130 remains disposed within the first notch 322 within the aperture 321 of the locking sleeve 320 ), the gate 110 can be freely moved back and forth between the closed position shown in FIG. 6A and an open position as shown in FIG. 6B . In some embodiments, the carabiner 300 may be configured such that, as the gate 110 is moved into the open position shown in FIG. 6B , the head 132 of the pin member may be urged out from the notch 322 in the upper surface 327 of the locking sleeve 320 within the elongated aperture 321 if the gate 110 (and the locking sleeve 320 ) is pivoted to or beyond a threshold angle relative to the body 102 of the carabiner 300 . By way of example and not limitation, the locking sleeve 320 and the first end 104 of the body 102 may be sized and configured such that, as the gate 110 (and locking sleeve 320 ) is pivoted to a threshold angle relative to the body 102 of the carabiner 300 , as shown in FIG. 6B , a lower surface of the locking sleeve 320 will abut against the body 102 proximate the first end 104 thereof at a pinch point 340 . If the gate 110 (and locking sleeve 320 ) is further pivoted inward beyond the threshold angle relative to the body 102 , the contact between the body 102 and the locking sleeve 320 at the pinch point 340 will cause the locking sleeve 320 to slide longitudinally along the gate 110 toward the second end 106 of the body 102 and away from the pin member such that the head 132 of the pin member is urged out from the first notch 322 within the elongated aperture 321 of the locking sleeve 320 . After the head 132 of the pin member is urged out from the first notch 322 within the elongated aperture 321 of the locking sleeve 320 , the spring member between the gate 110 and the locking sleeve 320 will prevent the head 132 of the pin member from returning to the notch 322 in the absence of an applied external force, and will urge the locking sleeve 320 to rotate to the locked position shown in FIG. 6C . When the gate 110 (and the locking sleeve 320 ) is in the open position shown in FIG. 6B , a projection 326 of the locking sleeve 320 that extends downward (from the perspective of FIG. 6B ) past the pin member and laterally beside the first end 104 of the body 102 , prevents the locking sleeve 320 from rotating about the gate 110 responsive to the forces applied by the spring member until the gate 110 (and the locking sleeve 320 ) has pivoted back toward the closed position to an extent that the nose 108 of the second end 106 of the body 102 has passed at least partially through the aperture 328 in the end of the locking sleeve 320 proximate the second end 106 of the body 102 . Stated another way, the projection 326 may be sized and configured to pass over the body 102 only after the gate 110 (and the locking sleeve 320 ) has pivoted back toward the closed position and the nose 108 has passed at least partially through the aperture 328 in the locking sleeve 320 . Thus, the projection 326 maintains the aperture 328 in the locking sleeve 320 in alignment with the nose 108 until the nose 108 has passed at least partially through the aperture 328 . If the aperture 328 were not maintained in alignment with the nose 108 until the nose 108 had passed at least partially through the aperture 328 , the spring member could cause the locking sleeve 320 to rotate relative to the gate 110 such that the aperture 328 were not aligned with the nose 108 , in which case interference between the nose 108 and the end of the locking sleeve 320 proximate the second end 106 of the body 102 would prevent the gate 110 (and the locking sleeve 320 ) from returning to the closed position. As the projection 326 clears the body 102 , the nose 108 will be partially disposed within the aperture 328 . Interference between the nose 108 and the surfaces of the locking sleeve 320 within the aperture 328 , however, will prevent the locking sleeve 320 from further rotation about the gate 110 response to the forces acting on the locking sleeve 320 until the nose 108 has passed entirely through the aperture 328 in the locking sleeve 320 and into the receptacle in the gate 110 . As the gate 110 moves from the open position shown in FIG. 6B into the closed position shown in FIG. 6C , the nose 108 of the second end 106 of the body 102 will pass entirely through the aperture 328 in the locking sleeve 320 , at which point, the spring member between the gate 110 and the locking sleeve 320 will cause the locking sleeve 320 to further rotate in the counter-clockwise direction about the gate 110 until the head 132 of the pin member is forced into a second notch 324 in the upper surface 327 of the locking sleeve 320 within the elongated aperture 321 . The end of the elongated aperture 321 adjacent the second notch 324 prevents further rotation of the locking sleeve 320 about the gate 110 in the counter-clockwise direction. When the head 132 of the pin member is disposed within the second notch 324 , the locking sleeve 320 is in a locked position in which the aperture 328 is not aligned with the nose 108 and the end of the locking sleeve 320 proximate the second end 106 of the body 102 locks the gate 110 to the nose 108 in the closed position. Thus, when the gate 110 is closed and the locking sleeve 320 is in the locked position, as shown in FIG. 6C , the locking sleeve 320 prevents the gate 110 from inadvertently being opened. To unlock the locking sleeve 320 and open the gate 110 , a user may apply a force to the locking sleeve 320 to move the locking sleeve 320 out of the locked position shown in FIG. 6C and to rotate the locking sleeve 320 about the gate 110 until the aperture 328 in the locking sleeve 320 is aligned with the nose 108 , at which point the gate 110 may be opened. In particular, a user may apply a force to the locking sleeve 320 to cause the locking sleeve 320 to slide longitudinally along the gate 110 toward the second end 106 of the body 102 , and to cause the locking sleeve 320 to rotate in the clockwise direction about the gate 110 in such a manner as to cause the head 132 of the pin member to be dislodged out of the second notch 324 , to align the aperture 328 with the nose 108 , and to open the gate 110 . Optionally, a user may move the locking sleeve 320 from the locked position shown in FIG. 6C to the retainable unlocked position shown in FIG. 6A , in which the head 132 of the pin member is lodged within the first notch 322 in the locking sleeve 320 . If the user lodges the head 132 of the pin member within the first notch 322 in the locking sleeve 320 before or after moving the gate 110 to the open position, the locking sleeve 320 may be freely opened and closed, as previously described herein, without causing the locking sleeve 320 to move into the locked position (shown in FIG. 6C ) until the locking sleeve 320 is pivoted relative to the body 102 beyond the threshold angle. If, however, the user does not lodge the head 132 of the pin member within the first notch 322 in the locking sleeve 320 before or after moving the gate 110 to the open position, the locking sleeve 320 will return to the locked position shown in FIG. 6C when the gate 110 returns to the closed position after the user opens the gate 110 . Thus described, embodiments of carabiners of the present invention may be said to be operable in each of a “manual” mode and an “automatic” mode. For example, when the locking sleeve 120 , 220 , 320 of the carabiner 100 , 200 , 300 is in the retainable unlocked position relative to the gate 110 (i.e., when the head 132 of the pin member 130 is disposed within the first notch 122 , 222 , 322 of the locking sleeve 120 , 220 , 320 ), the carabiner 100 , 200 , 300 may be said to be operable in a manual mode in which the gate 110 may be manually moved back and forth between the open and closed position, so long as the gate 110 is not pivoted beyond the threshold angle relative to the body 102 of the carabiner 100 , 200 , 300 , and the head 132 of the pin member 130 is not dislodged from the first notch 122 , 222 , 322 . To operate the carabiner 100 , 200 , 300 in the automatic mode, the gate 110 may be opened and pivoted relative to the body 102 of the carabiner 100 , 200 , 300 beyond the threshold angle to urge the head 132 of the pin member 130 out of the first notch 122 , 222 , 322 , or the locking sleeve 120 , 220 , 320 may simply be moved by a user from the retainable unlocked position to the locked position without opening the gate 110 . As a result, the locking sleeve 120 , 220 , 320 will automatically move to the locked position the next time the gate 110 returns to the closed position. Although the foregoing description contains many specifics, these are not to be construed as limiting the scope of the present invention, but merely as providing examples of certain embodiments of the invention. Additional embodiments of the invention may be devised which do not depart from the spirit or scope of the invention. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents, rather than by the foregoing description of certain embodiments of the invention.	Carabiners have a gate that is movable between a closed position and an open position, and a locking member that prevents opening of the gate when the gate is in the closed position and the locking member is in a locked position. The locking member is biased to the locked position. The locking member is also movable to a retainable unlocked position. Methods of manufacturing such carabiners include configuring a locking member of a carabiner to move between a locked position and a retainable unlocked position, and biasing the locking member to the locked position. Methods of using a carabiner include positioning a locking member in a retainable unlocked position, opening a gate of the carabiner, and allowing the locking member to at least substantially automatically move to a locked position as the gate is closed.	8
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a reversible revolving illuminated musical and speaking Christmas tree stand and more specifically to a remotely controlled stand of this type. The stand is adapted to rotatably support an artificial or natural Christmas tree, other decorative trees or other devices for reversible rotational movement about a generally vertical axis. The stand includes a structure for supportingly engaging the tree or other device, structure for illuminating the tree or other device and an audio device for producing a musical rendition, song or the like relating to the tree or other device and a remote control by which all functions of the stand can be independently controlled at a distance from the stand. The stand has a housing shaped and configured to carry out the theme or symbolism of the tree or other device. The remote control includes an infrared transmitter which is preferably hand held and the stand includes an infrared signal receiver to control the functions in accordance with the infrared control device. 2. Description of the Prior Art Various types of rotating and non-rotating Christmas tree stands are well known in the art as well as stands or Christmas trees which incorporate lights, music and manual control apparatus. Also, various remote control devices are provided to enable remote control of various electrically powered appliances or devices. The following U.S. patents generally relate to this field of endeavor. U.S. Pat. Nos. 4,153,860 5,485,068 5,647,569 5,455,750 5,634,622. While the prior art discloses various remotely controlled devices and manually controlled stands supporting a Christmas tree for rotation, the specific arrangement of the components and the remote control characteristics of the present invention are not found in the prior art. SUMMARY OF THE INVENTION The remotely controlled, illuminated, musical and speaking Christmas tree stand of the present invention comprises a hollow housing of generally star shaped configuration. The tree stand includes an upwardly and inwardly tapering peripheral wall having a substantially flat closed and removable bottom which can rest upon a supporting surface. The stand further includes structure at its upper end for clampingly engaging a Christmas tree, a drive mechanism for reversibly rotating the Christmas tree, a mechanism providing electrical energy to decorative light bulbs on the tree and an audio device for producing music, song and/or vocal message traditionally associated with the Christmas season. In accordance with the present invention, the stand is provided with an infrared control signal receiver either on the housing or extended from the housing which receives infrared signals transmitted from a portable battery powered control device. The portable control device is provided with manually controlled switches to selectively and independently energize the lights on the tree, selectively and reversibly rotate the tree and selectively operate the audio device. This enables operation and control of the functional capabilities of the stand from a remote location by utilizing the portable infrared control device in a manner well known in the art of remote controlling various appliances such as television and the like. Accordingly, it is an object of the present invention to provide a stand for a Christmas tree or similar device utilizing components that enable the tree or other device to be reversibly rotated about a vertical axis, that enable decorative lights on the tree or other device to be energized when rotating or when stationary and that actuate an audio device for producing music or songs relating to the Christmas season, or that relate to other decorative devices supported by the stand. All functional operations of the stand are controlled by a remote infrared control device that transmits signals to an infrared signal receiver either on the stand or located adjacent to and connected to the stand to facilitate operation of all functions of the stand from a remote location. Another object of the invention is to provide a remote control for a Christmas tree or other device as set forth in the preceding object in which the remote control device provides an infrared signal to the receiver associated with the stand for independently controlling each of the functions, operating selected multiple functions and simultaneous operation of all functions from a remote location. A further object of the invention is to provide a remotely controlled, illuminated, musical revolving Christmas tree stand which stably supports a natural or artificial Christmas tree and is simple, safe and dependable in operation, and relatively inexpensive to manufacture, maintain and operate. Still another object of the invention is to provide a Christmas tree stand having a star shaped configuration in green or other color or colors to conform with the symbolism of the tree and the Christmas season. These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a Christmas tree with the Christmas tree stand of the present invention supporting the tree. FIG. 2 is a top plan view of the stand of the present invention. FIG. 3 is an enlarged side elevational view of the stand of the present invention. FIG. 4 is a top plan view of the stand of the present invention with the top wall removed in order to illustrate the relationship of the components on the bottom wall. FIG. 5 is a vertical sectional view of the stand of the present invention, on an enlarged scale, taken along section line 5 — 5 on FIG. 4, with the top wall of the stand removed and spaced above the bottom wall. FIG. 6 is a bottom plan view of the top wall of the stand of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Although only one preferred embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, in describing the preferred embodiment, specific terminology will be resorted to for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. As used herein, the term “Christmas sounds” or “sounds” is intended to include music, songs, verbal message, or any combination, of the Christmas season or other circumstances consistent with the supported decoration. Referring to the drawings, the Christmas tree stand of the present invention is generally designated by reference numeral 10 and, as illustrated in FIG. 1, an artificial Christmas tree generally designated by reference numeral 12 is supported vertically by the stand 10 . The Christmas tree 12 will have vertical and circumferential dimensions enabling the stand 10 to stably support the tree 12 . The Christmas tree is also provided with strings of lights, decorative ornaments and other decorative materials, schematically illustrated at 13 , which are normally employed to decorate a Christmas tree. The tree 12 includes a trunk 14 received in the stand 10 and clampingly supported therein by clamp bolts or other clamp structure, generally designated by reference numeral 16 . The stand 10 includes a hollow housing, generally designated by reference numeral 18 , which has a generally star shaped configuration and includes a top wall 19 tapering downwardly and outwardly from its upper end to a lower end. A bottom wall generally designated by reference numeral 20 is attached to and forms a closure for the top wall 19 . FIGS. 2-6 illustrate in more detail the specific structure of the housing 18 including the top wall 19 and the bottom wall 20 , each of which are generally star shaped in configuration. The top wall 19 preferably includes a generally horizontal, planar pentagonal central top member 23 with the sides extending down from the top member 23 forming vertically depending walls 24 . Extending downwardly from each corner of the pentagonal top member 23 is a plurality of downwardly inclined ridges 26 each defined by a pair of inclined walls 28 and 30 . Each vertically depending wall 24 is connected to a ridge 32 which extends downwardly and outwardly in an inclined manner with each ridge 32 joining with a vertical wall 24 at a level below the pentagonal top 23 , as illustrated in FIG. 3 . The ridge 32 is defined by walls 34 and 36 . Adjacent inclined walls 34 and 30 are connected to form a valley 38 and adjacent walls 28 and 36 are connected to form a valley 40 . Thus, alternating ridges 26 and 32 and alternating valleys 38 and 40 define alternating star points 42 and 43 which are located at different radial distances from the vertical center of the housing as illustrated in FIGS. 2-6. The lower edges 27 and 33 of the ridges 26 and 32 are straight and in alignment to form a straight bottom edge on the top wall 19 . The bottom wall 20 includes a planar, horizontal panel or wall 44 provided with a periphery defined by longer and shorter star points 46 and 48 in alternating relation around the periphery of the bottom wall 20 . The tip ends of the star points 46 and 48 are oriented in different radial spaced relation to the center of the stand 10 . The entire periphery of the wall 44 is provided with an upwardly and inwardly inclined narrow flange 50 which extends above and below wall 44 . The upper edge of flange 50 telescopically receives the lower edges of the walls 28 , 30 , 34 , 36 of the top wall 19 with the flange 50 telescoping over the outer surface of the lower edge of the walls which define the star points 42 and 43 on the top wall 19 . The planar pentagonal top member 23 includes a central circular opening 52 (see FIG. 6) and vertical walls 24 extend downwardly to a point spaced a short distance above the lower edges 27 and 33 of the top wall 19 to provide rigidity to the top wall 19 . The bottom wall 44 includes a central short upstanding pentagonal flange 53 aligned with and forming a continuation of walls 24 . When assembled, the lower edges of walls 24 engage the upper edge of flange 53 to rigidify the central portion of top wall 19 together with the bottom wall 20 . The top wall 19 also includes reinforcing walls 54 extending outwardly from each apex of the pentagonal vertical walls 24 along the underside of the ridges 26 . The bottom edges of the reinforcing walls 54 are spaced so as not to protrude below the plane defined by the lower edge of the top wall 19 and are spaced above the bottom of the vertical pentagonal walls 24 . The top wall 19 is of unitary, monolithic construction, preferably of rigid plastic material which may be colored, preferably green or in any other color or colors desired depending upon the decorative device supported by the stand. As shown in FIG. 6, the bottom of the top wall 19 includes screw receiving studs 56 spaced inwardly from the underside of each star point at the outer end of each ridge 26 and 32 . The screw receiving studs 56 on ridges 32 are preferably spaced farther from the star point than the studs 56 on ridges 26 . Also, screw receiving studs 57 are spaced inwardly and upwardly from the lower end of certain of the valleys 40 between inclined walls 30 and 34 or 28 and 36 . These studs 56 and 57 are integral with the top wall 19 and receive fastening screws which extend through apertures 58 in the star points 48 of the bottom wall 44 which are aligned with studs 56 and through upstanding studs 60 on the bottom wall 44 which are aligned with the studs 57 . Mounted centrally in the bottom wall 20 and disposed within the upstanding pentagonal flange 53 is a vertically extending generally cylindrical housing, generally designated by reference numeral 62 , having a plurality of partial peripheral flanges 63 along the base edge thereof which are secured to the bottom wall panel 44 , such as by screw fasteners. The cylindrical housing 62 includes a reversible motor and a rotary electrical contact assembly interiorly thereof, the details of which are not shown and which are of conventional construction. An output clamp ring 64 extends above the housing 62 and is driven by the motor. The clamp ring 64 includes a cylindrical interior 66 in which a Christmas tree trunk can be inserted. A plurality of radial clamp screws 68 are threaded into the clamp ring 64 and the inner ends of screws 68 clampingly engage the Christmas tree trunk inserted into interior 66 in a well known manner. The clamp screws 68 may have a loop shaped outer end to facilitate rotation of the clamp screws. Also, an electrical conductor 70 extends through the clamp ring 64 and terminates in a receptacle 72 at its exposed free end in a manner such that the receptacle 72 is oriented adjacent the upper end of the housing 62 but is movable in relation thereto within the limits of the flexible electrical conductor 70 . This electric receptacle 72 enables a male electrical plug to be inserted therein to supply electrical energy to the lights on a Christmas tree supported by the stand. The lower end of the cylindrical housing 62 includes a plurality of electrical conductors 74 extending from a circuit board 76 that is mounted on the bottom wall panel 44 . The circuit board 76 is provided with electrical components which receive electrical energy from an electric cord 78 having a male plug 80 on the free end thereof. The electric cord 78 extends through a notch 82 in the flange 50 and through a strain relief structure 84 in a recess 86 in the bottom wall panel 44 . The circuit board 76 also includes components of an audio producing device including a speaker 88 mounted in an opening 90 in the bottom wall panel 44 . The speaker 88 includes a perforated cover positioned below the bottom wall panel 44 to facilitate sound emissions from the audio producing device. The electrical components include switches for the reversible electric motor, connecting electrical energy to the female receptacle 72 and operating the audio producing device. These switches are operated by electrical conductors 92 extending to an input jack 94 in the bottom wall panel 44 which opens to the bottom. A male jack component is inserted from the undersurface of the panel 44 from an electrical conductor 96 which extends out through a notch 98 in the flange 60 and has the infrared receiver 98 at the outer end thereof. The infrared receiver 98 can then be positioned so that it is accessible to an infrared transmitter 100 which has multiple switches 102 including a switch for selectively actuating the audio producing device, a switch for selectively energizing the electric lights on the Christmas tree and a switch for selectively rotating the clamp ring 64 and Christmas tree supported thereby in either rotational direction. The foregoing is considered as illustrative only of the principles of the invention. Since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. For example, while infrared signals are the preferred means for remote transmission, other wireless frequencies or signals for remotely controlling the operation of the stand could be used. Further, other possible decorative devices supported by the stand 10 could be controlled remotely by the transmitter 100 , such as blinking lights, lighted color wheels and the like. Accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.	A reversible revolving, illuminated, musical and speaking Christmas tree stand that is remotely controlled. The stand rotatably supports an artificial or natural Christmas tree, other decorative trees or other devices supported for rotational movement about a generally vertical axis. The stand includes a structure for reversibly rotatably, supportingly engaging a tree or other device, a structure for illuminating the tree or other device and a structure for producing musical renditions, songs or the like relating to the tree or other device and an infrared remote control by which all functions of the stand can be independently controlled without approaching the tree. The stand has a housing shaped and configured to carry out the theme or symbolism of the tree or other device.	0
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to antenna diversity receivers, particularly those suitable for use for wideband radio reception and more particularly for multi-carrier systems. [0003] 2. Description of the Prior Art [0004] Antenna diversity receivers use multiple antennas to overcome signal quality degradation caused by multipath fading. If the antennas are arranged such that their outputs fade independently, then the signals from the antennas can be combined to produce a signal with higher quality since it is unlikely that both antennas (branches) will simultaneously be in a deep fade. This allows the receiver to be used in areas with lower signal strengths or to provide higher signal quality and reliability within the normal system coverage area. [0005] A common form of diversity combiner is a switch combiner, in which only one complete receiver is needed. The receiver is switched between the antennas and makes a judgement as to which antenna provides the strongest signal. Numerous schemes for doing this exist, but it is believed that none of them address suitable strategies for wideband channels. In all cases, switch combining performs less well than selection combining, in which two receivers are available so that the performance of both antennas can be simultaneously monitored, but a switch is used to select the signal from only one of them at a time. Maximal ratio combining (MRC) involves using, simultaneously, a plurality of receivers each operating on a signal from a respective antenna, and using signal processing to combine the outputs of the receivers. This gives better performance than either switch combining or selection combining, but is somewhat more expensive. [0006] In a wideband fading channel, the bandwidth of the transmitted signal is wider than the coherence bandwidth of the channel (see S. R. Saunders, “Antennas and Propagation for Wireless Communication Systems”, John Wiley & Sons, ISBN 0471986097, July 1999, for precise definitions). This implies that different parts of the received signal bandwidth will be faded to different extents, so the choice of the best antenna is not clear. A switch combiner could make a decision based on the total power available over the whole signal bandwidth, by performing a vector sum of the respective channel outputs of the receiver filter. However this yields only minor diversity gain when the delay spread is large, i.e. when there are significant delayed versions of the signal arriving at the receiver due to multipath echoes The results when selection combining is used instead of switch combining are not significantly better. [0007] Choosing a single antenna, based on whichever criteria, and using this for the reception of the whole ISDB-T bandwidth can lead to significant degradation in performance. Mostly, this will be due to the fact that somewhere within the signal bandwidth there will be a deep null, so although at some carriers within the bandwidth there may be excellent diversity gain, there is none achieved at other carriers, with the resultant diversity gain essentially an average across the bandwidth. [0008] Given that delay spread has been shown to produce this significant performance degradation, it would be attractive to have a combining technique which avoids this problem, but without the expense of MRC systems, and preferably using only one receiver. [0009] Accordingly, it would be desirable to provide a switch diversity combiner which preserves the low cost of having a single receiver, but has improved performance in high delay-spread environments than available from any conventional single receiver combiner. SUMMARY OF THE INVENTION [0010] Aspects of the present invention are set out in the accompanying claims. [0011] According to a further aspect of the invention, a diversity switch combiner for use in systems for receiving wideband signals is arranged to split the received signal into separate channels each carrying a respective frequency band. Respective switch means are provided for each channel in order to switch the input of each channel between different antennas. A switch control determines the switch settings in accordance with the result of a comparison operation in which the signal qualities for different settings are compared. [0012] The invention is particularly applicable to multi-carrier signals which are transmitted in the form of symbols comprising a guard period followed by a useful part of the symbol, the guard period corresponding to the end of the useful part. In this case, the quality estimation is preferably performed during a guard period, so that the antenna switching can be carried out without causing a significant deterioration of performance. [0013] According to a still further aspect of the invention, a diversity switch combiner forms a path between the antennas and the receiver output, which path includes at least two channels each for carrying a respective frequency band of the received signal. Each channel has an independently operable switch means for selecting which of the signals from the antennas are fed through the channel. The receiver output is based on the combined output of the channels. Accordingly, enhanced performance throughout the frequency range of the received radio signal can be achieved. [0014] The combiner is preferably located between the antennas and the receiver, and thus conveys RF signals to the receiver. Alternatively, the combiner could be located within the receiver, e.g. in the IF section, although in this case separate versions of the circuits prior to the combiner would have to be provided for the respective channels. [0015] The approach can be extended to as many channels as desired, until the resilience against delay spread is sufficient to account for the prevailing channel conditions. Ultimately the performance can be made to approach arbitrarily closely to the performance of switching performed on every carrier independently. At this level diversity gains may be around 9 or 10 dB. BRIEF DESCRIPTION OF THE DRAWINGS [0016] Arrangements embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: [0017] FIG. 1 schematically illustrates a receiver system according to a first embodiment of the invention; [0018] FIG. 2 is a more detailed block diagram of the receiver system of FIG. 1 ; and [0019] FIG. 3 schematically illustrates a receiver system of a second embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0020] In FIG. 1 , a basic embodiment of the invention is shown. The receiver system 2 , which is intended for receiving OFDM (Orthogonal Frequency Division Multiplex) signals, includes an antenna section 4 , a switch combining section 6 and a receiver circuit 8 which includes means for converting the received signal to baseband. [0021] In the antenna section 2 , two antennas, A 1 and A 2 , are arranged so that their outputs fade independently. The outputs are coupled to a switch block 20 of the switch combining section 6 . The block 20 incorporates two switches 22 and 24 and is operable to couple each output to a respective one of two staggered tuned filters 26 , 28 . The filters are arranged to select only one respective half of the received signal band each. The outputs of the filters 26 and 28 are combined in a combiner 30 , the output of which is delivered to the receiver circuit 8 . [0022] The switch combining section 6 also includes switch logic 32 responsive to signals from the receiver circuit 8 for choosing which of the antennas should be routed to each of the filters. This can be based on a comparison of the possible switch states examined during a guard period of the received signal. Thus a deep null in one antenna in one half of the segment can be avoided if it is not present in the other antenna. The system is then resilient to almost twice the delay spread as conventional full-band switching. [0023] FIG. 2 illustrates the system in more detail. The two antennas, A 1 and A 2 , are arranged so as to produce substantially independent fading signals. The signals are split via splitters 40 and 42 and sent to electronically controlled switches 22 and 24 . A control unit 44 selects each of the four possible states of switches 22 and 24 sequentially during an initial phase of operation, typically during a symbol guard interval. The output signal from switch 22 is filtered by a high-pass filter 26 , which outputs only the upper half of its input signal bandwidth, while switch 24 is connected to a low-pass filter 28 which outputs only the lower half of its input signal bandwidth. The two filter outputs are summed by combiner 30 and the result forms the input to a conventional receiver circuit 8 . At its output, the receiver circuit produces individual carriers of the OFDM signal, which are normally demodulated by a demodulator 46 . [0024] The carrier outputs are sent to a quality estimator 48 to estimate the quality of the resulting signal, typically using soft decision information or otherwise. There are various known ways of estimating signal quality. For example, the distances of the carrier outputs from the correct positions for the carrier constellation can be measured. It is not necessary to use all the carriers for quality estimation, although the carriers which are used should be spread throughout the frequency spectrum of the signal. It is possible to base the quality estimation on pilot carriers, by comparing their actual values with the known values they should adopt in a clean, noise-free system. Alternatively, spectrum estimation based on a limited number of samples could be used. [0025] The quality estimates for the four possible switch states are stored in a memory unit 50 . A bank 52 of six comparators forms pairwise comparisons of all four quality estimates. The comparators are connected to a bank of four logical AND gates and associated NOT operations 54 which selects the largest of the four quality estimates. The result selects one of the four switch states within the control unit 44 and sets the switch states to correspond to the highest quality combination of branches. If the quality estimations can be achieved sufficiently quickly, which will depend on the process used, the switch state is preferably set during the current symbol, and more preferably before the beginning of the useful part of the symbol. The state is held for as long as appropriate (typically a symbol duration) before the whole process is repeated. If the quality estimation takes too long to be of value for the current symbol, the switch state could instead be set for the useful part of the next symbol (after first altering the state during the next guard interval for obtaining further quality estimates). It is not necessary to repeat the process regularly. Instead the process could be triggered by a detected deterioration in quality. [0026] The receiver circuit 8 shown in FIG. 2 includes an RF tuner 82 , which receives the signals from the antennas via the switches 22 and 24 and filters 26 and 28 . The output of the tuner 82 is delivered to a down converter and IF amplifier 84 , which supplies its output to an IF-to-baseband converter 86 . The baseband signals from the converter 86 are sent to an FFT and channel estimation block 88 , which generates the OFDM carrier signals for the receiver circuit output. The baseband signals are also delivered to a symbol synchronisation circuit 90 , for synchronising the operation of the FFT and channel estimation block 88 , and to a sample clock and frequency synchronisation circuit 92 which synchronises the operations of the down converter and IF amplifier 84 and the IF-to-baseband converter 86 . [0027] This is merely one example of a number of different types of receiver circuits which could be employed in the system of FIG. 2 . In alternative arrangements, the switches 22 and 24 and filters 26 and 28 could instead be provided within the receiver circuit 8 , for example between the down converter and IF amplifier 84 and the IF-to-baseband converter 86 , with suitable modifications to the filter characteristics and duplication of the circuits preceding the converter 86 . [0028] Another development of the basic approach is shown in FIG. 3 . This embodiment is largely similar to that of FIG. 1 , and like integers have like reference numerals. In the embodiment of FIG. 3 , however, the antenna branches have been combined in a weighted combiner 60 , with a fixed weighting to form another branch. This may be regarded as a fixed beam-steering network, which will have less fading in some parts of the band than either of the antennas alone. Again this can be extended to multiple combining networks and multiple sub-band filters. In the limit of having enough combining networks and sub-band filters, this approach will be capable of the same performance as maximal ratio diversity combining performed on every carrier. This approach will thus only produce a small extra performance gain over the previous case. [0029] In all cases two basic front ends (each comprising a splitter, a switch and a filter) are required in order to have simultaneous access to signals from both antennas. This may not necessarily be more economical than performing MRC at the receiver IF, but the choice will depend on the relative costs of the various RF components. [0030] It is envisaged that the receiver circuit which is used to generate the main receiver output is also used for obtaining the measurements for the quality estimates, but this is not essential. [0031] The diversity system proposed is applicable to any wideband radio system, using any number of antennas. It is particularly relevant to applications at user terminals where power consumption, size and cost are particularly critical, whereas base stations will usually implement diversity combiners which use one receiver circuit per branch. [0032] Particular systems which are applicable are: ISDB-T DAB DVB UMTS cdma2000	A diversity switch combiner for use in systems for receiving wideband signals is arranged to split the received signal into separate channels each carrying a respective frequency band. Respective switch means are provided for each channel in order to switch the input of each channel between different antennas. A switch control determines the switch setting in accordance with the result of a comparison operation, preferably performed during a guard period, in which the signal qualities for different settings are compared.	7
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims the benefit of U.S. Provisional Application Ser. No. 61/965,985 entitled “Electric Current Based Device and Method for Mapping Deep Anomalous Zones of Electrical Resistivity” filed Feb. 13, 2014 BACKGROUND OF THE INVENTION [0002] This invention relates to a multi-component system and method for deep well mapping of zones of anomalous electrical resistivity. More particularly, the invention utilizes currently employed coated, corrosion resistant well casings to carry an electric current down to an exposed end of the production tubing portion at depth whereby the strength of the transmitted current is sufficient to generate electric fields. The effect on these fields in anomalous zones proximate the end of the well is a function of the nature of the materials in the zone, which effects can be monitored by appropriately placed sensors. [0003] Electric and electromagnetic geophysical methods are used to map the distribution of electrical resistivity in the subsurface of the earth. Generally known methods employ transmitters that induce electrical currents to flow in the ground. The transmitters can be sources of electric current injected by electrodes implanted in the soil or rock and connected to a power supply or the transmitters can be loops of wire carrying an alternating current which produces an alternating magnetic field that, by Faraday's law of induction, induces an electromotive force in the ground that, in turn, drives currents in the ground. In either case, the currents induced depend on the distribution of resistivity in the ground and these induced currents produce secondary electric and magnetic fields that can be measured by receivers which are usually separated from the transmitter. For instance, the receivers may include two separated electrodes in contact with the ground and across which a voltage is measured that is proportional to the electric field at that point. Receivers may also include a variety of sensors designed to measure the magnetic fields that accompany the induced currents. The transmitters and receivers can be on the surface or in the ground. [0004] These methods can be used to determine the distribution of electrical resistivity in the ground. For example, the methods can be used to characterize the layering of the ground so as to identify a resistive layer that contains oil or gas, a conductive layer containing saline water, or a clay layer that might be an impermeable barrier for hot water in a geothermal setting, or the like. A more specific application of such methods is to determine the size and electrical resistivity of limited regions in the ground. Examples are zones of petroleum rich rock in an oilfield that has not been drained by the existing oil wells in the field (essentially bypassed oil), zones of electrically conducting rocks reflecting the presence of metallic ore minerals, a zone of enhanced conductivity brought about by the injection under pressure of a fluid mixture designed to cause a fracture or a fluid mixed with solid conductive particles intended to keep the fracture open (proppant), or a zone of decreased resistivity caused by the injection of carbon dioxide for sequestration for mapping and monitoring steam or chemicals injected to reduce viscosity and increase production from an oilfield formation. In all of these applications, the goal is to detect and, if possible, delineate a zone whose electrical resistivity is distinctly different from the resistivity of the overall volume of the ground below the surface in a specified region (referred to as the background resistivity). [0005] A specific, known transmitter-receiver configuration that is particularly effective for detecting and delineating finite zones with a resistivity different from the background resistivity is an electric current source in which at least one of the electrodes is located at depth in the vicinity of the target zone. This configuration is shown in FIG. 1 . This traditional surface-based configuration employs two current electrodes on the surface, A-B, that inject current I into the ground. Collectively this structure is usually referred to as the transmitter. Current is carried to each electrode from a power supply (not shown) by an insulated cable. Another pair of two separated electrodes on the surface, usually referred to as a dipole, is used to measure the voltage drop V between two points caused by the injected currents. This measuring dipole is usually referred to as the receiver. The measurement is usually described in terms of an electric field, in volts per meter, obtained by simply dividing the measured voltage by the separation distance L of the electrodes. The receiver dipole usually occupies successive positions on the surface over the target zone. A variant on this configuration, to which this invention is directed, uses a deep electrode B′ to inject the current adjacent to the anomalous zone being investigated. [0006] In either case, the current in the ground is distorted by the presence of the anomalous zone. In the situation where the anomalous zone is less resistive than the surroundings, current is deflected or channeled into the zone and the resulting secondary fields, seen at some distance away such as in a nearby borehole or on the surface, can be represented by an induced current dipole in the zone whose strength is proportional to the size of the anomalous zone and the difference in resistivity. The electric fields measured along the surface are perturbed or offset from the value they would have in the absence of the anomalous zone. The fields on the surface are thus composed of the fields that would be present for the background in the absence of the anomalous zone, plus the secondary or anomalous fields caused by anomalous currents caused by the zone of anomalous resistivity. The measurement of the anomalous fields on the surface permits the determination of the depth, size and resistivity contrast of the particular target zone. [0007] The perturbation in surface electric fields caused by a small zone is itself small and difficult to recognize in practical field data because normal surface field variations due to inhomogeneities in the background, and particularly due to near surface resistivity inhomogeneities, dwarf the anomalies of deep features. However, the goal of many electrical surveys is to detect changes in the zone of interest over time scales appropriate to the subsurface activity. The background resistivity can be assumed invariant over these scales and so small changes in resistivity in small zones at depth can be detected. [0008] The importance of placing an electrode at the depth of the anomalous zone is shown quantitatively in FIG. 2 . The target zone for this illustrative model is a vertical, 100 meter by 200 meter conductive sheet 202 which is oriented in the vertical or x-z plane, while both the transmitter and receiver are on the x axis. The sheet is characterized by the product of its conductivity and thickness (in this model the conductivity thickness product is 10 (note: conductivity is the reciprocal or inverse of resistivity and the units can be Siemens, S, per meter; the conductivity thickness is therefore in Siemens). The background resistivity in this example is 100 Ohm meters (ρ=100 Ωm). The secondary surface electric fields, Ex, are plotted as a function of distance from the well in FIG. 2B for two source current configurations: a surface bipole A-B, and an inverted L-shaped array A′-B′ with the B′ current electrode in the vicinity of the target. [0009] The surface field anomaly from this deeply buried conductive zone is 100 times larger than that produced from the surface array when one of the electrodes is buried. The results in this figure are presented for surface electric fields in Volts per meter (V/m) for a source current of one Ampere (A). In a typical survey, a current of 10 A would be used and the voltage difference between two measuring points 100 m apart would be measured. The voltage measured in the model study shown would therefore be 1000 times the field values in the plot. For example, at a distance of 300 m from the well-head using the deep electrode, the secondary field is 10 −8 Volts per meter so the voltage difference on a receiving dipole would be 10 −5 Volts and easily measured. With this in mind, it becomes clear that a whole new window on subsurface features is opened if the current source can be located close to the desired zone of investigation. [0010] The problem that has kept this deep source configuration from being implemented is that there has been no practical method of placing a current electrode with its attendant insulated current cable at the bottom of a typical drilled well. Almost all wells drilled for hydrocarbons, geothermal fluids or steam, carbon dioxide injection, water etc. are lined with a metallic pipe called a casing. A normal casing plan for a well involves successive casings of varying lengths and progressively smaller diameter. A large diameter hole is drilled through the near surface, usually unconsolidated, formations. A reduced diameter hole is then drilled and cased to greater depth and, finally, an even smaller diameter hole is drilled and cased to the desired maximum depth. The last, smallest diameter casing is referred to as the production casing. In some situations, a continuous length of tubing, referred to as the production tubing, is inserted inside the production casing. At each stage, cement is forced into the annular space between the drilled hole and the casing, with the cement filling the space for a short distance between the casings from the bottom of the larger casing. The space between the innermost casing and the next largest diameter casing in the upper portion of the well is empty. Most important, there needs to be continuous free access to the production casing. However, equipment devices called packers, which seal off certain depths in the well and tubing used to withdraw or inject fluids, occupy the production casing such that there is no room for a heavy current carrying cable or electrode. [0011] With the above in mind, there is seen to be a need for a system and method which will enable a current electrode to be effectively provided at the bottom of a drilled well in order to enhance the ability to map subsurface zones of anomalous electrical resistivity. SUMMARY OF THE INVENTION [0012] The present invention is directed to a system and method for delivering current to a bottom section of a well. More specifically, a source of current is connected to a middle segment of a well casing or a tubing inserted into the well casing (herein generically referred to as a “well conduit”). The middle segment is electrically isolated from a first segment, and is formed or treated, such as by applying an outer coating of an electrically resistive (and perhaps also corrosion resistant) material, oxidizing the outer portion thereof, or the like, so as to be electrically resistive. With this arrangement, sufficient current is transported along and inner wall portion of the middle segment to an uncoated end section to generate an electric field at the bottom section of the well. Changes in the generated electric field resulting from the nature of materials in the ground in surrounding zones can then be detected by surface or below ground monitors or sensors, with the measured results being used for the detection and delineation of subsurface features. [0013] According to certain embodiments of the invention, the segments form a production casing and, in at least one other embodiment, the segments form part of a tube inserted into an existing well casing. In either case, a lowermost segment (or segments) is left bare at the bottom of the well and a current source is connected to the intermediate or middle segment, below an uppermost segment which is electrically isolated from the intermediate segment, such by an insulative coupler, such that the current will flow through the intermediate segment to reach the bare metal segment at the bottom of the well. The outer, insulating layer prevents current from ‘leaking’ off or dissipating from the outer portion intermediate segment into surrounding casings or the ground. With this arrangement, current can now be transmitted to the end of the casing without interfering with any equipment or operations within the intermediate segment during well production or operation. [0014] Additional objects, features and advantages of the invention will become more readily apparent from the following detailed description when taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The present invention is described with respect to particular exemplary embodiments thereof and reference is accordingly made to the drawings in which: [0016] FIG. 1 is a schematic illustration of a prior art method for current mapping of anomalous underground zones. [0017] FIG. 2A is a schematic representation of a vertical fracture zone used here to represent a typical zone of anomalous resistivity. [0018] FIG. 2B is a graphical logarithmic plot of surface anomalous fields caused by a deep zone of anomalous resistivity vs. distance from a well. [0019] FIG. 3 is a schematic view of a well illustrating an embodiment constructed in accordance with the present invention. [0020] FIG. 4 is a detailed view of an insulating coupler illustrated in FIG. 3 . DETAILED DESCRIPTION OF THE INVENTION [0021] As will become fully apparent below, the invention relies on an insulated casing to play the role of the insulated current cable conducting current to the downhole electrode, B′ of FIG. 1 . More specifically, with reference to FIG. 3 , a well 100 is depicted including a surface casing 102 , an intermediate casing 104 and an innermost or production casing 106 . Depending on the depth and purpose of well 100 , there may be one or more intermediate casings 104 (herein collectively referred to as the intermediate casing). The depth of surface casing 102 is limited in the figure as the surface casing 102 would typically extend to just below the near surface, unconsolidated sediments or zones of surface ground water. As just shown on the left portion of surface casing 102 , cement would be pumped into the annulus between the surface casing 102 and the surrounding ground. The depth to which surface casing 102 extends down into the ground will vary from well to well and generally depends on the near surface ground. In typical oil wells, outer or surface casing 102 would extend down anywhere from 10 feet to a hundred feet or so. Within surface casing 102 , intermediate casing 104 extends a distance usually in the range of up to half the final depth of well 100 . The space between the lower part (not separately labeled) of each successive casing and the next is filled with cement 108 , as illustrated on the left portion of FIG. 3 . In this arrangement, the intermediate casing 104 serves to keep the upper reaches of well 100 relatively open to facilitate easy entrance and withdrawal of a drill bit (not shown) needed for extending production casing 106 to a depth of the target zone. [0022] The innermost or production casing 106 can serves to inject fluids into a production zone or extract fluids from that same zone. As detailed below, at least part of production casing 106 is coated with a corrosion resistant or prevention layer 112 which, by reason of its corrosion prevention properties, is an electrical insulator. This corrosion prevention coating 112 thus prevents current from passing or dissipating from casing 106 to the surroundings (note some leakage could occur but it is minimal). In the embodiments of this invention, corrosion prevention coating 112 thus permits the transmission of an electric current from the surface to the end of production casing 106 . In the illustrated embodiment, the end of production casing 106 is represented by last segment 110 which is bare metal or a metal that is electrically insulated. Typically, production casing 106 will extend a significant distance into the ground from a well head 128 at the surface, oftentimes going down anywhere from two thousand to fifteen thousand or more feet. [0023] It is common practice in the drilling industry to use a production casing coated with a tough corrosion resistant, insulating layer to prevent casing corrosion. Utilizing a corrosion prevention layer which is also an electrical insulator, i.e., a coating which is electrically resistive, has until now not been of interest in installing casing for conventional applications. To achieve the goal of using the casing for the transmission of current to lower end 110 of the production casing 106 in accordance with the invention, it is necessary to specify the coating for production casing 106 and to further specify that the lowest segment or segments 110 be left uncoated or otherwise not insulated electrically so that they act as a bare metal electrode. [0024] Various different coating options are available, with the pipe coating options including, but not limited to, tape, tar, epoxy and polyurethane coatings. One available corrosion preventing layer includes a coating material supplied by Bond-Coat Inc. of Odessa Tex., USA, www.bondcoat.com. More specifically, this company currently produces an overall coating which can be used on a casing or tubing that consists of a first coat of epoxy resin, a second coat of ground flint aggregate and then a top coat of more resin. The coating thickness is 40-50 mils and exhibits a temperature resistance to 200 F. The resin and ground flint are both electrical insulators. Another source is Tenaris Global Services Corp. of Houston Tex., USA, which at http://www.tenaris.com/en/Products/OffshoreLinePipe/Coating/ExternalAnticorros ion.aspx discusses various anticorrosion coatings, usually applied to pipelines, either for land or sub-sea applications. These coatings are of two types, either epoxy or epoxy with a bonding transition layer and an overlay of extruded polythene or polypropylene. A three layer coating is said to have “high dielectric resistance”. By way of a further example, Liberty Coatings of Morrisville, Pa., USA, www.libertycoating.com, produces two-layer coatings involving butyl rubber overlaid with polyethylene. [0025] In any case, with the insulating coating 112 exhibiting the electrical resistive characteristic, when a current connection is provided at the upper end of the production tubing 106 , the current will be transmitted along the entire length of the casing to its exposed end 110 without current, or at least with minimal current, leaking off casing 106 to the surroundings. The electrical current conducted down an inner wall portion of casing 106 is sufficient at end 110 to create the electric fields used in the mapping of the anomalous zones. In a preferred embodiment, the electrical signal is provided to inner casing 106 through an insulated cable 114 which is connected to a current source 116 that is grounded through electrode 117 . At its other end, cable 114 is attached to insulated production casing 106 through a connector 118 . In one embodiment, connector 118 is a bolt such that cable 14 is bolted directly to the metal casing 106 of well 100 . [0026] In an exemplary embodiment, the current source 116 is constituted by a power supply with a voltage range of up to a few hundred volts and capable of supplying 10 to 30 Amps or more of current. The currents are driven at one or multiple frequencies in the range of 0.01 Hz to several thousand Hz. Examples of such power supplies are the GGT-3, GGT-10 and GGT-30 transmitter power supplies from Zonge Engineering and Research, Tucson, Ariz., USA (zonge.com). [0027] If the cable 114 from current supply source 116 located near the distant grounded electrode 117 were simply connected to the metallic casing at the well head 128 , it would then also be connected to the surface equipment which holds the casing in place and which connects production casing 106 to the surface valves and piping required to convey the fluids produced or injected to or from the well 100 . To avoid this problem, the insulated current supply cable 114 is connected to the inner portion of insulated, production casing 106 below a casing coupler segment 120 that is electrically non-conducting, thus electrically isolating top casing segment 128 (which may be uncoated or otherwise not insulated) as illustrated in FIG. 3 . In one embodiment of the invention, coupler segment 120 comprises a commercially available section of fiberglass casing. However, other coupler materials can be employed, including, but not limited to, non-conductive high strength materials such as Kevlar® fabric impregnated with high strength resins such as epoxy. By way of example, coupler segment has a length of approximately 30-40 feet. [0028] In this embodiment, current provided by source 116 can safely be carried to an inner portion of coated inner production casing 106 below, typically located at shallow depth, about 40-50 feet, while remaining fully, or at least substantially entirely, insulated from the surface equipment, valves, piping etc. by the insulative segment 120 . With this arrangement, even with conducting fluid filling innermost production casing 106 , negligible current will flow back up to an upper metallic segment at well head 128 . At this point, it should be noted that various arrangements could be employed to establish the desired electrical connection between the power source and the inner portion of the second or intermediate segment of production casing 106 . In fact, it is even possible to utilize existing well structure, such as a push rod, for this purpose. [0029] Certainly, if insulative coupler segment 120 must support the weight of a heavy well, such as a steel cased well, from the near surface to full well depth, insulated coupler segment 120 may be customized. For instance, as detailed in FIG. 4 , insulative coupler 120 may have a thickened fiberglass body, and incorporate an inner threaded steel ring 122 which threads coupler 120 to the end of casing segment 106 ′. In the illustrated embodiment, female threads 123 of ring 122 are dimensioned to mate with male threads 124 of casing 106 ′. Of course, the arrangement of the threads could be reversed and other known mechanical couplings could be employed. [0030] At this point, it should also be recognized that the present invention can be employed in connection with both a new well and in retrofitting an existing well. In the case of a new well, it will be appreciated that both a coated intermediate production casing and an uncoated bottom end section would be specified, along with the inclusion of the insulative coupler 120 of the invention, such as illustrated in FIGS. 3 and 4 . On the other hand, for use with existing, uncoated steel cased wells, another approach is required for delivery of a current to the bottom of the well. In this additional embodiment, a smaller diameter, production casing (or tubing) coated with an electrically insulating material can be lowered into the existing well, with the bottom end segment of the tubing left uncoated. The upper coated end would be similarly attached to an insulative coupler like coupler 120 illustrated at FIG. 4 . Therefore, this embodiment includes corresponding first, second and third interconnected segments, and the current is again supplied to the second or intermediate segment for transmission to the third segment at the bottom section of the well and into nearby geological zones adjacent the well, while being prevented from dissipating to around the well along the second segment by the outer electrically resistive coating. [0031] Notably, in this scenario, the bare tubing electrode may be close to, or touching the uninsulated production casing. Should the exposed end section make contact with or short to the existing, uncoated metal casing, charge will leak off as well, specifically exponentially in the direction moving upwardly along the length of the production casing. However, such leakage will dissipate to near zero within a few hundred meters of the casing bottom, thus creating a more distributive, rather than point, type of source. On this point, reference is made to Schenkel and Morrison (Schenkel, C. J. and Morrison, H. F., 1990, Effects of well casing on potential field measurements using downhole current sources: Geophys. Prosp., 38, no. 6, 663-686, and Schenkel, C. J. and Morrison, H. F., 1994, Electrical resistivity measurement through metal casing: Geophysics, 59, no. 7, 1072-1082), where the authors have shown that, although current does flow axially along the casing, current also leaks off radially into the surrounding conducting ground so the casing acts to distribute current flowing into the ground over a finite length of the casing at the bottom of the well. Far from causing a problem, this spreading of the deep current source can actually increase the secondary fields from a nearby zone of anomalous resistivity. [0032] In any case, based on the above, the system and method of the invention provides for transmitting an electric current from a bottom section of a well utilizing a well conduit, such as a well casing or a tube inserted into a well casing, including a first segment proximate a well head, a second segment including an inner portion which is electrically conductive and an outer portion which is electrically resistive (i.e., substantially entirely or at least mostly insulated electrically), and a third segment which is located at or near the bottom section of the well and is electrically conductive. A power source provides the electric current through an electrical connection to the inner portion of the second segment for transmitting the electric current from the power source to the second segment, through the second segment to the third segment which establishes a downhole electrode. From the third segment, the electric current is transmitted into nearby geological zones adjacent the well, particularly for mapping purposes. [0033] Although described with reference to particular embodiments of the invention, it should be understood that the foregoing detailed description of the invention is provided for purposes of illustration and is not intended to be exhaustive or to limit the invention to the embodiments disclosed. Therefore, additional embodiments of the invention can be employed without departing from the spirit of the invention. For instance, very often, producing or injecting fluids from or to the zone of the bottom of the well is carried out by means of a small continuous tube which is inserted in the well and has a diameter smaller than the inner diameter of the production casing. This tube can be inserted at any time after the well is completed. In further accordance with the invention, this insulated production tubing (not shown) can actually be used to convey current to the bottom of the well. Like the insulated inner production casing, this tube can be coated or otherwise treated with an insulating layer and, by leaving a section uncoated or otherwise not insulated at the bottom, the tube can now play the role of the desired insulated cable and electrode. An insulating section of the tubing, similar to that shown in FIG. 3 for the inner casing, would likewise need to be employed. In any case, it should be readily apparent that the invention can be applied to vertical wells, angled wells, horizontal wells, or any combination thereof. Also, although described with reference to a production well, the invention can be employed for use other types of wells including, by not limited to, pilot wells, observation wells, and wells dedicated to injecting fluids into a production zone.	A system and method are provided for delivering current to a lower exposed end of a well in which a source of current is connected to a middle section of a well casing or tubing inserted in the casing with the middle section being electrically isolated from a first or upper section by an insulative coupler and treated to be electrically resistive. A cable is attached to the middle section and used to deliver current along the wall of the middle section to the lower exposed end such that the lower exposed end is used to generate an electric field in nearby geological zones. Changes in the generated electric field resulting from the nature of materials in the geological zones can be detected by surface or below ground monitors or sensors.	4
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source apparatus. For example, the surface light source apparatus according to the present invention is used as a backlight for a liquid crystal display device. 2. Description of the Related Art FIG. 1 shows an enlarged cross-sectional view, partially broken away, of schematic structure near a light source of a conventional surface light source apparatus. In a light source 12 used in a surface light source apparatus 11 , vertical and horizontal surfaces and a rear surface of a transparent resin 14 sealing a LED 13 are covered with a case 15 made of a white resin, and only a front face of the transparent resin 14 is exposed from the case 15 . The light source 12 is mounted on a flexible printed board 16 . The light source 12 is vertically inverted such that the flexible printed board 16 is faced up, and the front face of the light source 12 faces an end face (light incident plane 18 ) of a light guide plate 17 . A diffusing sheet 20 is disposed while facing a light outgoing plane 19 of the light guide plate 17 , and a reflector plate 21 is disposed while facing a back side of the light guide plate 17 . For example, Japanese Patent Application Laid-Open No. 2003-215584 discloses the surface light source apparatus having the above configuration. In order to achieve a low profile of the light guide plate 17 or enhancement of light use efficiency, as shown in FIG. 1 , a height of the front face of the transparent resin 14 in the light source 12 is equal to a thickness of the light guide plate 17 , and the light source 12 is disposed such that a center in a height direction of the transparent resin 14 coincides with a center in a thickness direction of the light guide plate 17 . Therefore, a gap is generated between the light outgoing plane 19 of the light guide plate 17 and the flexible printed board 16 , and light L leaking from a gap between the light source 12 and the light incident plane 18 of the light guide plate 17 passes to the outside through the gap between the light outgoing plane 19 and the flexible printed board 16 without passing through the light guide plate 17 as shown by an arrow of FIG. 1 . As a result, although the gap between the light source 12 and the light incident plane 18 of the light guide plate 17 is covered with the flexible printed board 16 , an eye-shaped high-brightness region is generated near (portion designated by the letter P of FIG. 1 ) an edge of the flexible printed board 16 in front of the light source 12 , and the region glitters like an eye when the surface light source apparatus 11 is obliquely observed, which remarkably impairs evenness in a light emission surface of the surface light source apparatus 11 . Because a rim sheet (frame material) is overlapped on the flexible printed board 16 , when an opening of the rim sheet is decreased to extend an edge on an inner peripheral side of the opening of the rim sheet to the inside from an end on a light guide plate side of the flexible printed board 16 , the eye-shaped high-brightness region is hardly viewed. However, when the opening of the rim sheet is excessively decreased, because an effective region of the surface light source apparatus becomes small compared with an outer shape size of the surface light source apparatus, from a practical standpoint, it is difficult to excessively decrease the opening of the rim sheet. In a backlight disclosed in Japanese Patent Application Laid-Open No. 2002-357823, gap between the light source and the light guide plate is covered with a light blocking tape. At this point, when the whole surface of the light blocking tape is bonded to the light outgoing plane of the light guide plate, an adhesive agent constitutes a light guide, the light leaks from between the light guide plate and the light blocking tape, and the edge of the light blocking tape also glitters like an eye. Therefore, in the backlight disclosed in Japanese Patent Application Laid-Open No. 2002-357823, only both ends of the light blocking tape are bonded to the light outgoing plane with an adhesive agent, and the light blocking tape is not bonded in at least the light source portion. However, in the backlight disclosed in Japanese Patent Application Laid-Open No. 2002-357823, because the light blocking tape is not bonded to the light guide plate in the light source portion, the gap between the light blocking tape and the light guide plate is generated in that portion. Therefore, as with the surface light source apparatus shown in FIG. 1 , the light leaks from the gap between the light guide plate and the light blocking tape, and the phenomenon in which the edge of the light blocking tape glitters like an eye cannot sufficiently be solved. In a surface light source apparatus disclosed in Japanese Patent Application Laid-Open No. 2005-321586, the flexible printed board adheres to the light guide plate with a double-sided adhesive tape. In the double-sided adhesive tape, a reflecting layer is formed on one of surfaces of a tape substrate, and a tackiness agent having a high light transmission property is provided on a surface of the reflecting layer. A colored layer is formed on the other surface of the tape substrate, and the tackiness agent having a high light transmission property is provided on a surface of the colored layer. The tackiness agent on the reflecting surface side of the double-sided adhesive tape adheres to the light guide plate, and the tackiness agent on the colored layer side adheres to the flexible printed board. Therefore, the light leaking from between the flexible printed board and the light guide plate is reflected by the reflecting layer, whereby the light is incident on the light guide plate. However, in the surface light source apparatus disclosed in Japanese Patent Application Laid-Open No. 2005-321586, the light passes through the tackiness agent of the double-sided adhesive tape adhering to the light guide plate, and the light leaks from the gap between the flexible printed board and the light guide plate. Even if the leaking light is reflected by the reflecting layer of the double-sided adhesive tape, at least part of the reflected light is transmitted through the light guide plate and reflected by the reflector plate on the back side, and the light is transmitted through the light guide plate again and outputted from the light outgoing plane. Therefore, even though the gap between the flexible printed board and the light guide plate is closed by the double-sided adhesive tape, there is no effect of eliminating the eye-shaped high-brightness region. In a surface light source apparatus disclosed in Japanese Patent No. 3371052, end portions of the light guide plate and diffusing sheet are inserted into a recess provided in a front face of the light source, an end portion of the light outgoing plane of the light guide plate is covered with a case of the light source, and the end face of the diffusing sheet is covered with a light blocking wall provided in the case of the light source, a reflecting sheet in the light source and the like, thereby preventing the leakage of the light from the gap between the light guide plate and the case of the light source. However, because a cold-cathode tube is used in the surface light source apparatus disclosed in Japanese Patent No. 3371052, the surface light source apparatus disclosed in Japanese Patent No. 3371052 cannot be applied to the surface light source apparatus having the light source in which a LED is used. That is, because the light source in which a LED is used is a micro component having a depth of several millimeters, a width of several millimeters, and a thickness not more than 1 mm, it is actually difficult that the end portions of the light guide plate and diffusing sheet are inserted into the recess of the light source, and the it is difficult to realize the practical application of the surface light source apparatus disclosed in Japanese Patent No. 3371052 for the light source in which a LED is used. SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a surface light source apparatus which can prevent the generation of the eye-shaped high-brightness region, caused by the light leaking from the flexible printed board covering the gap between the light guide plate and the light source or from the gap between the light blocking member and the light guide plate, around the edge of the flexible printed board or light blocking member near the light source. A surface light source apparatus according to a first aspect of the present invention includes a point light source; a light guide plate which spreads light introduced from the point light source into a planar shape to output the light from a light outgoing plane; and a light blocking member which covers parts of the point light source and the light outgoing plane of the light guide plate, wherein a gap shielding member is projected toward the light outgoing plane from a surface on a side facing the light outgoing plane of the light blocking member, and at least a portion facing the light outgoing plane in the gap shielding member is made of a material having a light blocking property. As used herein, the point light source shall mean a light source in which a micro light emitting element such as a LED is used. In the surface light source apparatus according to the first aspect of the present invention, the gap between the light blocking member and the light outgoing plane of the light guide plate is closed by the gap shielding member, and at least the portion on which the light having relatively large luminosity is incident in the gap, i.e., the portion facing at least the light outgoing plane in the gap shielding member is made of the material having a light blocking property. Therefore, the phenomenon in which the light of the point light source leaks from the gap and glitters like an eye can be prevented to improve the evenness of the light emission surface. A surface light source apparatus according to a second aspect of the present invention includes a point light source; a light guide plate which spreads light introduced from the point light source into a planar shape to output the light from a light outgoing plane; and a point light source mounting wiring board which is disposed to cover parts of the point light source and the light outgoing plane of the light guide plate, wherein a gap shielding member is projected toward the light outgoing plane from a surface on a side facing the light outgoing plane of the wiring board, and at least a portion facing the light outgoing plane in the gap shielding member is made of a material having a light blocking property. In the surface light source apparatus according to the second aspect of the present invention, the gap between the wiring board and the light outgoing plane of the light guide plate is closed by the gap shielding member, and at least the portion on which the light having relatively large luminosity is incident in the gap, i.e., the portion facing at least the light outgoing plane in the gap shielding member is made of the material having a light blocking property. Therefore, the phenomenon in which the light of the point light source leaks from the gap and glitters like an eye can be prevented to improve the evenness of the light emission surface. In the surface light source apparatus according to the second aspect of the present invention, preferably the gap shielding member is not projected toward a side of the point light source from an end face facing the point light source of the light guide plate, and the gap shielding member is not projected from an end on a side of the light outgoing plane of the wiring board. Accordingly, the wiring board is exposed between the point light source and the end face (light incident plane) of the light guide plate while the wiring board is not covered with the gap shielding member. Therefore, at least part of the light outputted onto the wiring board side between the point light source and the end face of the light guide plate is reflected by the wiring board and is incident on the light guide plate, which enables enhancement of the light use efficiency. Because the gap shielding member is not projected from the end on the light outgoing plane side of the wiring board, it is not necessary that the gap shielding member projected from the wiring board be hidden by the rim sheet, and the opening of the rim sheet can be widened to increase the effective area of the surface light source apparatus. In the surface light source apparatus according to the first or second aspect of the present invention, preferably the whole of the gap shielding member is made of the material having the light blocking property. Accordingly, the light does not pass through the gap, which further improves the effect of preventing the eye-shaped high-brightness region. In the surface light source apparatus according to the first or second aspect of the present invention, preferably the material having the light blocking property is a black material or a light absorbing material. Accordingly, because the light is not reflected by the gap shielding member, the stray light is hardly generated. In the surface light source apparatus according to the first or second aspect of the present invention, preferably the gap shielding member is located in front of the point light source in a light outgoing direction. Accordingly, the gap shielding member can be provided to the necessity minimum. In the surface light source apparatus according to the first or second aspect of the present invention, preferably the gap shielding member is located at least in front of the point light source in a light outgoing direction or both sides of the point light source when viewed from a direction perpendicular to the light outgoing plane of the light guide plate. Accordingly, because the light source is surrounded by the gap shielding member, the light of the light source hardly leaks in any direction, and the light emission surface of the surface light source apparatus can further be uniformalized. A surface light source apparatus according to a third aspect of the present invention includes a point light source; a light guide plate which spreads light introduced from the point light source into a planar shape to output the light from a light outgoing plane; a diffusing sheet which is disposed while facing the light outgoing plane of the light guide plate; and a light blocking member which covers parts of the point light source, the light outgoing plane of the light guide plate, and the diffusing sheet, wherein a light absorbing layer is formed in a surface on a side facing the light outgoing plane of the light blocking member, and the light absorbing layer is brought into contact with a surface of the diffusing sheet. In the surface light source apparatus according to the third aspect of the present invention, the light absorbing layer provided in the light blocking member is brought into contact with the diffusing sheet, the light of the point light source which enters the gap between the light blocking member and the light guide plate is diffused by the diffusing sheet, and the light is incident on the light absorbing layer of the light blocking member and absorbed by the light absorbing layer. Therefore, the phenomenon in which the light of the point light source leaks from the gap and glitters like an eye can be prevented to improve the evenness of the light emission surface. In the surface light source apparatus according to the third aspect of the present invention, preferably a gap shielding member is projected toward a surface facing the light outgoing plane of the light blocking member at a position withdrawn from a front end of the light blocking member. At this point, the gap shielding member may be in contact with the surface light source apparatus, or may have a micro gap. Accordingly, the gap between the light blocking member and the light guide plate is closed to hardly pass the light by the gap shielding member. Even when the gap exists between the gap shielding member and the light guide plate, the light of the point light source which enters the gap between the gap shielding member and the light guide plate is diffused by the diffusing sheet, and the light is incident on the light absorbing layer of the light blocking member and absorbed by the light absorbing layer. Therefore, the phenomenon in which the light of the point light source leaks from the gap and glitters like an eye can be prevented to improve the evenness of the light emission surface. In the surface light source apparatus according to the third aspect of the present invention, preferably a prism pattern is formed in a surface facing the light outgoing plane of the diffusing sheet. Accordingly, because the course of the light can be bent by the prism pattern, the course of the light passing through the gap between the light blocking member and the light guide plate or the light passing between the gap shielding member and light guide plate can be bent and absorbed more surely by the light absorbing surface of the light blocking member. The means for solving the problem in the present invention has the feature in which the above-described constituent components are appropriately combined, and various variations of the present invention can be made by the combination of the components. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross-sectional view, partially broken away, of a schematic structure of a conventional surface light source apparatus; FIG. 2 shows a cross-sectional view, partially broken away, of a schematic structure of a surface light source apparatus according to a first embodiment of the present invention; FIG. 3A shows a perspective view of a flexible printed board on which a light source is mounted, and FIG. 3B shows a plan view of the flexible printed board; FIG. 4 shows a plan view of an enlarged light source portion of FIG. 3B ; FIG. 5A shows a cross-sectional view taken along a line X-X of FIG. 4 , and FIG. 5B shows a cross-sectional view taken along a line Y-Y of FIG. 4 ; FIG. 6 shows a schematic cross-sectional view for explaining action of the surface light source apparatus according to the first embodiment; FIG. 7 shows a relationship between a radiation angle and a relative luminosity of a LED; FIG. 8 shows a plan view of a flexible printed board in which a gap shielding member is provided in a different region; FIG. 9 shows a cross-sectional view, partially broken away, of a schematic structure of a surface light source apparatus according to a second embodiment of the present invention; and FIG. 10 shows a cross-sectional view, partially broken away, of a schematic structure of a surface light source apparatus according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 2 shows a cross-sectional view, partially broken away, of schematic structure of a surface light source apparatus according to a first embodiment of the present invention. A surface light source apparatus 31 is used as a backlight for a liquid crystal display device. The surface light source apparatus 31 mainly includes a light source 33 , a light guide plate 34 , a reflector plate 35 , a diffusing sheet 36 , and a rim sheet 37 which are mounted on a flexible printed board 32 . The light guide plate 34 is molded in a thin plate made of a transparent resin material having a high refractive index such as polycarbonate resin and polymethyl methacrylate (PMMA). Although a light outgoing plane 38 of the light guide plate 34 is formed in a substantially smooth surface, the light outgoing plane 38 is formed in a finely coarse surface when viewed closely. A number of fine deflection patterns 34 a are formed in a surface (hereinafter referred to as back side) opposite the light outgoing plane 38 of the light guide plate 34 . The fine deflection pattern 34 a totally reflects the light guided through the light guide plate 34 to output the light to the outside from the light outgoing plane 38 . There is no particularly limitation on the shape and the arrangement of the deflection patterns 34 a. For example, a number of deflection patterns 34 a which are recessed in the form of triangular grooves in the back side of the light guide plate 34 are coaxially arranged while substantially centered on the light source 33 . The light emitted from the light source 33 is incident on the light guide plate 34 from a light incident plane 39 of the light guide plate 34 , and the light is totally reflected repeatedly between the back side and the light outgoing plane 38 of the light guide plate 34 . The light incident on the deflection pattern 34 a during the total reflection between the back side and the light outgoing plane 38 is total-reflected from the deflection pattern 34 a and outputted to the outside from the light outgoing plane 38 . Because the reflector plate 35 faces the back side of the light guide plate 34 , the reflector plate 35 reflects the light leaking from the back side of the light guide plate 34 and returns the light into the light guide plate 34 , thereby improving the light use efficiency. The diffusing sheet 36 is disposed on the light outgoing plane 38 , and a periphery on an upper surface side of the diffusing sheet 36 is covered with the frame-shape rim sheet 37 . Therefore, the light outgoing from the light outgoing plane 38 is diffused by the diffusing sheet 36 and outputted toward a front face. The light source 33 is a light source (point light source) in which a LED 40 (chip) is used. The one light source 33 may be used in the surface light source apparatus 31 or a plurality of the light sources 33 may be used in the surface light source apparatus 31 . The LED 40 is sealed in a transparent resin 41 . An upper surface, a lower surface, right and left side faces, and a rear surface of the transparent resin 41 are covered with a case 42 made of a white resin. Therefore, the front face of the transparent resin 41 is exposed from a front opening of the case 42 . When the LED 40 emits the light, the light from the LED 40 travels through the transparent resin 41 and outputted to the outside from the front face of the light source 33 , or the light is reflected one or a plurality of times at a boundary between the transparent resin 41 and case 42 and outputted to the outside from the front face of the light source 33 . As shown in FIGS. 3A and 3B , the light source 33 is mounted on the flexible printed board 32 along with an electronic component 43 such as a Zener diode. A gap shielding member 44 is formed in front of the light source 33 in the surface of the flexible printed board 32 . FIG. 4 shows a plan view of the enlarged light source of FIG. 3B , FIG. 5A shows a cross-sectional view taken along a line X-X of FIG. 4 , and FIG. 5B shows a cross-sectional view taken along a line Y-Y of FIG. 4 . As shown in FIG. 5A , in the flexible printed board 32 , a conductor layer 47 (pattern wiring) formed by a rolled copper foil having a thickness of 35 μm is laminated on a base film 45 made of polyimide having a thickness of 12.5 μm by an adhesive agent layer 46 having a thickness of 20 μm, and a cover film 49 made of polyimide having a thickness of 12.5 μm is further laminated on the conductor layer 47 by an adhesive agent layer 48 having a thickness of 25 μm. As shown in FIG. 5B , in a portion where the light source 33 is mounted, the cover film 49 and the adhesive agent layer 48 are partially removed to expose the conductor layer 47 , the light source 33 is placed on the flexible printed board 32 , and an electrode provided on the lower surface of the light source 33 is soldered to the respective conductor layer 47 of the flexible printed board 32 with a solder 50 . Therefore, the lower surface of the case 42 of the light source 33 is aligned with the same height as the upper surface of the flexible printed board 32 . As shown in FIG. 4 , the gap shielding member 44 adheres to a front region of the light source 33 while being separated by a distance of a=0.25 mm from the front face of the light source 33 . In a longitudinal direction, the gap shielding member 44 is formed in symmetric in relation to a center line C passing through the center of the light source 33 , and an end of the gap shielding member 44 is withdrawn by b=0.6 mm from an end of the flexible printed board 32 . As shown in FIGS. 5A and 5B , the gap shielding member 44 is bonded onto a cover film 49 of the flexible printed board 32 . The gap shielding member 44 is formed by a light blocking layer 51 , a reinforcing plate 52 , and an adhesive agent layer 53 in order from the upper layer. The reinforcing plate 52 is formed by a thin plate made of polyimide. In the light blocking layer 51 , a surface treatment layer is formed on the surface of the reinforcing plate 52 , and silk-screen printing of a black coating material (for example, CR-18C-KT1 produced by Asahi Chemical Research Laboratory Co., Ltd.) is performed onto the surface treatment layer. The surface treatment layer includes an underlying layer made of Ni and an upper layer made of Au, and the surface treatment layer is formed by NiAu electrolytic plating. The surface of the black coating material is roughened and delustered. The adhesive agent layer 53 is a transparent thermosetting epoxy adhesive agent, and the gap shielding member 44 is adhesively bonded onto the flexible printed board 32 by the adhesive agent layer 53 . As shown in FIG. 6 , the thickness of the gap shielding member 44 is equal to a thickness e of the face on the mounting side of the case 42 . For example, in the present embodiment, the face on the mounting side of the case 42 has the thickness of 72.5 μm. Therefore, the gap shielding member 44 has the total thickness of 72.5 μm in which the light blocking layer 51 has the thickness of 12.5 μm, the reinforcing plate 52 has the thickness of 25 μm, and the adhesive agent layer 53 has the thickness of 35 μm. The light source 33 thus mounted on the flexible printed board 32 is vertically inverted while the flexible printed board 32 is faced up, and the light source 33 is arranged to face the light incident plane 39 of the light guide plate 34 . The gap shielding member 44 provided in the flexible printed board 32 is brought into surface contact with an end portion in the light outgoing plane 38 of the light guide plate 34 . A height f of the transparent resin 41 of the light source 33 is equal to the thickness of the light guide plate 34 , and the light source 33 is disposed such that the center in the height direction of the transparent resin 41 coincides with the center in the thickness direction of the light guide plate 34 . Furthermore, because the thickness of the gap shielding member 44 is equal to the thickness e of the face on the mounting side of the case 42 , a gap is not generated between the surface of the light blocking layer 51 of the gap shielding member 44 and the light outgoing plane 38 of the light guide plate 34 . Therefore, in front of the light source 33 , the gap between the flexible printed board 32 and the light outgoing plane 38 is closed by the gap shielding member 44 . Particularly, in the gap, the region adjacent to the light outgoing plane 38 is closed by the light blocking layer 51 and the reinforcing plate 52 which are of a light blocking material. As a result, the light emitted from the light source 33 hardly passes between the flexible printed board 32 and light outgoing plane 38 , and the eye-shaped high-brightness region is hardly generated at an edge of the flexible printed board 32 or rim sheet 37 to uniformize the light emission surface. Because the gap shielding member 44 has the transparent adhesive agent layer 53 , the light incident on the gap shielding member 44 from the light source 33 is transmitted through the adhesive agent layer 53 . However, the light transmitted through the adhesive agent layer 53 has little influence due to a directivity characteristic as described below. As shown in FIG. 6 , it is assumed that the height f of the transparent resin 41 is set to 650 μm, the distance d between the front face of the light source 33 and the light incident plane 39 is set to 250 μm, the thickness e on the mounting side of the case 42 is set to 72.5 μm, the thickness of the light blocking layer 51 is set to 12.5 μm, the thickness of the reinforcing plate 52 is set to 25 μm, and the thickness of the adhesive agent layer 53 is set to 35 μm. The light emitted to the direction ranging from 55° (θ 1 ) to 58° (θ 2 ) relative to an optical axis direction (perpendicular to the front face of the light source 33 and the light incident plane 39 ) is incident from the center of the front face of the light source 33 on an end face of the transparent resin 41 . On the other hand, referring to a LED directivity characteristic curve of FIG. 7 , in the case of the radiation angle θ 1 =58°, the relative luminosity becomes K of about 42% in FIG. 7 . When the radiation angle ranges from 55° to 58°, the luminosity becomes only about 42 to 47% relative to a front-face luminosity (luminosity in the 0° direction), so that it does not matter because of the small luminosity. The fact can also be confirmed through experiments. FIG. 7 shows a directivity characteristic of a LED (model name: NESW008C) presented by Nichia Corporation (http://www.nichia.co.jp/specification/jp/led_smd/NESW008CT.pdf). Obviously, because the adhesive agent layer 53 desirably does not transmit the light, the (e.g. black) adhesive agent or tackiness agent having the light blocking property may be used as the adhesive agent layer 53 . The end of the gap shielding member 44 on the side of the light source 33 is configured so as not to be projected toward the side of the light source 33 from the light incident plane 39 . When the gap shielding member 44 is projected from the light incident plane 39 , the light traveling upward in the gap between the light source 33 and the light incident plane 39 is absorbed by the gap shielding member 44 . On the contrary, when the gap shielding member 44 is not projected from the light incident plane 39 , the flexible printed board 32 is exposed in the upper portion of the gap between the light source 33 and the light incident plane 39 . Therefore, like a light beam L 1 shown in FIG. 6 , the light traveling upward in the gap between the light source 33 and the light incident plane 39 is reflected by the flexible printed board 32 is incident on the light guide plate 34 , so that the light use efficiency can be enhanced. The end of the gap shielding member 44 on the side opposite the light source 33 is configured so as not to be projected from the end of the flexible printed board 32 . When the gap shielding member 44 is projected from the end of the flexible printed board 32 , in order to hide the gap shielding member 44 projected from the flexible printed board 32 , it is necessary to further reduce the opening of the rim sheet 37 . Therefore, the effective region of the surface light source apparatus 31 is reduced by the reduced opening of the rim sheet 37 . In the case where the light blocking layer 51 of the gap shielding member 44 has a light absorbing property, when the light blocking layer 51 comes into optically close contact with the light outgoing plane 38 of the light guide plate 34 , the light guided through the light guide plate 34 is absorbed by the light blocking layer 51 when entering the region where the light blocking layer 51 comes into close contact with the light outgoing plane 38 , which possibly causes loss. Therefore, in the surface light source apparatus 31 , the light outgoing plane 38 of the light guide plate 34 and/or the surface of the light blocking layer 51 are roughened such that the optically close contact is hardly established between the light outgoing plane 38 and the surface of the light blocking layer 51 . As shown in FIG. 8 , the gap shielding member 44 may be provided in the region surrounding the light source 33 in the surface of the flexible printed board 32 . Alternatively, the gap shielding member 44 may be provided in the form of a U-shape so as to surround the front face and side faces of the light source 33 . Desirably the gap shielding member 44 is brought into contact with the light outgoing plane 38 of the light guide plate 34 to the extent where the gap shielding member 44 is not brought into close contact with the light outgoing plane 38 . However, a micro gap may be generated between the gap shielding member 44 and the light outgoing plane 38 . Second Embodiment FIG. 9 shows a cross-sectional view, partially broken away, of a schematic structure of a surface light source apparatus according to a second embodiment of the present invention. The rim sheet 37 whose surface constitutes a light absorbing tackiness agent layer is used in a surface light source apparatus 61 . That is, the rim sheet 37 is formed by a double-sided adhesive tape (for example, NITTO DENKO No. 532 black produced by NITTO DENKO CORPORATION), and the rim sheet 37 has the total thickness of 125 μm. In the double-sided adhesive tape, black tackiness agents 62 and 64 are applied onto both surfaces of a core material 63 made of transparent polyethylene terephthalate (PET). An end portion of a diffusing sheet 65 disposed above the light outgoing plane 38 of the light guide plate 34 is extended to a position below the rim sheet 37 , and the tackiness agent 64 in the lower surface of the rim sheet 37 is bonded to the upper surface of the diffusing sheet 65 . A fine diffusing pattern is formed in the upper surface of the diffusing sheet 65 to diffuse the light, and a prism pattern is formed in the lower surface of the diffusing sheet 65 to refract the light outputted from the light outgoing plane 38 in the direction perpendicular to the diffusing sheet 65 . According to the surface light source apparatus 61 having the above structure, the light emitted from the light source 33 enters the gap between the rim sheet 37 and the light outgoing plane 38 of the light guide plate 34 , the light is incident on the lower surface (prism pattern) of the diffusing sheet 65 , a course of the light is bent upward, and the light is diffused by the upper surface of the diffusing sheet 65 . Therefore, the light incident on the diffusing sheet 65 passes through the diffusing sheet 65 , is incident on the lower surface of the rim sheet 37 , and is absorbed by the tackiness agent 64 . As a result, the generation of the eye-shaped high-brightness region can be prevented in front of the light source 33 . Particularly, the eye-shaped light spot viewable when observed from the direction ranging from 60° to 75° relative to the direction perpendicular to the light outgoing plane 38 can be eliminated in the present embodiment. On the other hand, because the transparent tackiness agent is used in the conventional rim sheet, even if the rim sheet 37 is bonded to the diffusing sheet 65 , the light transmitted through the diffusing sheet 65 is guided through the transparent tackiness agent layer, and the light is outputted from the end of the rim sheet 37 . Therefore, there is no effect of eliminating the eye-shaped high-brightness region. Although the flexible printed board 32 is not shown in the present embodiment, the flexible printed board 32 may be provided either on the upper side of the light source 33 or the lower side of the light source 33 . However, in the case where the flexible printed board 32 is disposed on the upper side of the light source 33 , it is necessary that the lower surface of the diffusing sheet 65 shall not be covered with the flexible printed board 32 . The tackiness agent 62 may be omitted. Third Embodiment FIG. 10 shows a cross-sectional view, partially broken away, of a schematic structure of a surface light source apparatus according to a third embodiment of the present invention. In a surface light source apparatus 71 , a light blocking tape is bonded to the lower surface of a light blocking member 72 to project a gap shielding member 73 . The light blocking member 72 is formed by a rim sheet or a light blocking tape. In the case where the light blocking member 72 is formed by a rim sheet, the light blocking tape which is of the gap shielding member 73 is bonded to the lower surface. In the case where the light blocking member 72 is formed by a light blocking tape, after the two layers of the light blocking tape are formed, an unnecessary portion of the lower-layer light blocking tape is removed to form the gap shielding member 73 . A diffusing sheet 74 is disposed on the light outgoing plane 38 of the light guide plate 34 , and a prism pattern 75 is formed in the lower surface of the diffusing sheet 74 . The gap shielding member 73 projected toward the lower surface of the light blocking member 72 such as the rim sheet and the light blocking tape is made to face the light outgoing plane 38 of the light guide plate 34 , and the lower surface of the light blocking member 72 is brought into contact with the upper surface of the diffusing sheet 74 . In the present embodiment, the gap shielding member 73 may be in contact with the light outgoing plane 38 of the light guide plate 34 , and the gap between the fight blocking member 72 and the light outgoing plane 38 may be closed by the gap shielding member 73 . In this case, because the gap between the light blocking member 72 and the light outgoing plane 38 is closed by the gap shielding member 73 , the light never leaks from the gap between the light blocking member 72 and the light outgoing plane 38 , which makes it possible to prevent the generation of the eye-shaped high-brightness region near the end portion of the light blocking member 72 . In the present embodiment, in the case where the light blocking member 72 is formed by a light absorbing material, a micro gap may be formed between the gap shielding member 73 and the light outgoing plane 38 as shown in FIG. 10 . In this case, after the gap between the light blocking member 72 and the light guide plate 34 is shielded by the gap shielding member 73 to make the light hardly pass therethrough, the course of the light passing between the gap shielding member 73 and the light outgoing plane 38 is bent upward by the prism pattern 75 . Then, the light is diffused by the diffusing sheet 74 , is incident on the light blocking member 72 , and is absorbed by the light blocking member 72 . Therefore, the light never leaks from the gap between the light blocking member 72 and the light outgoing plane 38 , and the generation of the eye-shaped high-brightness region can be prevented near the end portion of the light blocking member 72 . Although the flexible printed board 32 is not shown in the present embodiment, the flexible printed board 32 may be provided either on the upper side of the light source 33 or the lower side of the light source 33 .	A surface light source apparatus including a point light source, a light guide plate which spreads light introduced from the point light source into a planar shape to output the light from a light outgoing plane, and a light blocking member which covers parts of the point light source and the light outgoing plane of the light guide plate. A gap shielding member is projected toward the light outgoing plane from a surface on a side facing the light outgoing plane of the light blocking member. At least a portion facing the light outgoing plane in the gap shielding member is made of a material having a light blocking property.	6
BACKGROUND OF THE INVENTION The present invention relates generally to a spot welding method and apparatus and, more particularly, to such method and apparatus specifically adapted to prevent and/or minimize tip sticking, i.e. sticking of the welding tip to the workpieces, during ultrasonic vibratory spot welding. Ultrasonic vibratory spot welding processes for joining together two or more similar or dissimilar materials have been used for a number of years. Until recently, however, such methods were limited to use on thermoplastics, non-woven fabrics and metals where weld strength and integrity were not particularly important. This limitation was due, in large measure, to the problems associated with the ultrasonic welding methods employed, most of which were in prototype stages. In those instances when weld strength and weld integrity were important, i.e., when joining together structural aircraft panels and the like, resistance spot welding procedures were used. Ultrasonic spot welding procedures have recently demonstrated strong potential for improved sheet metal assembly at reduced cost when compared with resistance spot welding and adhesive bonding techniques. Early studies have indicated that welds effected using prototype ultrasonic welding equipment such as, for example, a Sonobond M-8000 ultrasonic spot welder, were superior to welds produced using conventional resistance spot welding procedures. These early trials indicated that for virtually any material combination, an ultrasonically produced spot weld has an ultimate yield strength of more than 2.5 times that of a weld produced using resistance spot welding equipment. Further tests indicated that ultrasonically produced spot welding can be accomplished with a 75% time and cost savings over conventional adhesive bonding techniques. Until now, however, ultrasonic spot welding for large structural metal parts was not possible in a production environment because of the numerous problems associated with the procedures. Ultrasonic vibratory welding is a metallurgical joining technique which utilizes high frequency vibrations to disrupt the surface films and oxides and which, therefore, promotes interatomic diffusion and plastic flow between the surfaces in contact without any melting of the materials. Briefly stated, the ultrasonic welding process consists of clamping or otherwise securing together the workpieces under moderate pressure between the welding tip and a support anvil and then introducing high frequency vibratory energy into the pieces for a relatively short period of time, i.e., from a fraction of a second to a number of seconds. In many instances, the pieces to be welded are also adhesively bonded together by the insertion of an adhesive bonding agent between the juxtaposed pieces before welding which result in a high strength, uniform joint with superior static and fatigue properties. One example of an ultrasonic spot welder particularly adapted for use on structural metal workpieces is the Sonobond Model M-8000 Ultrasonic Spot Welder marketed by Sonobond Corporation of West Chester, PA. This welder includes a transistorized, solid state frequency converter which raises standard 60 Hz electrical line frequency to 15-40 kHz and then amplifies the output. The high frequency electrical power travels through a lightweight cable to a transducer in the welding head where it is converted to vibratory power at the same frequency. The vibratory power is, thereupon, transmitted through an acoustic coupling system to the welding tip and then through the tip into and through the workpieces, with the vibratory energy effecting the weld. The Sonobond M-8000 Ultrasonic Spot Welder includes a wedge-reed, transducer coupling system which transmits lateral vibrations of a perpendicular reed member attached to it so that the welding tip at the upper end of the reed executes shear vibrations on the surface of the workpieces. The transducer includes piezoelectric ceramic elements encased in a tension shell assembly and operates at a nominal frequency of 15 kHz. A solid state frequency converter with a transistorized hybrid junction amplifier powers the welder. The converter operates at a nominal frequency of 15 kHz with a power output variable up to about 4000 RMS RF watts. The welder may be tuned to a precise operating frequency. The frequency converter includes a wide-band RF power measuring circuit which samples output power and detects forward power and load power based on the principle of bi-directional coupling in a transmission line. The signal is processed electronically to provide true RMS values which are selectively displayed on an LED panel meter as either the forward or load power. Forward power is the output of the frequency converter delivered to the transducer in the welding head while load power is the transducer drive power acoustically absorbed in the work zone. The difference between the two readings is the reflected power induced by the load impedance mismatch and is minimized during the welding operation by impedance matching techniques. In early trials using the prototype ultrasonic welding equipment, a serious "tip sticking" problem was encountered. The welding tip of the welder tended to adhere to the workpiece surfaces. The welding tips and anvils used in ultrasonic welding systems are considerably harder than the workpieces being welded and, as a result of both this and the metal flow which is induced by the vibratory power and clamp force application, the hardened welding tip oftentimes became smeared with the softer welded sheet. In early trials using the prototype ultrasonic welding equipment, the welding zones on the workpieces were characterized by torn and beaten aluminum and aluminum particles being transferred from the workpieces to the surface of the welding tip. After five or six welds, the material transfer tended to accelerate and the surface conditions of both the workpieces and welding tips deteriorated. As a result, it was found that the effective radius of the welding tip was enlarged by the build-up of material with a strong bond occurring between the welding tip and the metal sheet. At times, these bonds were as strong as the bonds formed between the metal workpieces being welded together. Tip sticking occurs as a result of local scuffing in the region of the contact area where the contact pressure is minimal. It also appears to be associated with a flexural condition where the sheet at the edge of the spot repeatedly rises up and strikes the welding tip producing a flapping action. The problem is, however, less pronounced when welding thicker sheets, thus confirming this theory. One solution to this "tip sticking" problem is to operate the welder at low power levels. This solution has, however, proved self-defeating since it precludes the generation of strong welds. A second solution is to replace the welding tips every fifth weld and clean them in a sodium hydroxide solution. Obviously, this second solution is not feasible for use in a production environment. The use of welding tips having different configurations and/or fabricated from different materials have also been tried. All of these attempts, however, have proven unsuccessful in overcoming this tip sticking problem. The present invention utilizes the placement of one or more shims between the welding tip and the workpieces and/or between the anvil and the workpieces. The high frequency energy which is emitted from the welding tip then passes through the shim and into the workpieces causing a weld to occur not only between the workpieces but as well between the shim and the workpiece. The bond which occurs between the welding tip and the shim and/or between the anvil and the shim is a weak bond and is easily broken so as to permit a peeling away of the shim from the workpieces when welding is completed. A strong bond, however, occurs between the workpieces. Somewhat similar approaches to this problem have been tried in the past. For example, U.S. Pat. No. b 3,533,155, which issued on Oct. 13, 1970 to A. Coucoulas, teaches the bonding of minute electronic leads using a compliant medium. This technique utilized extremely low energy, i.e. 1 watt, to weld very soft material, i.e. gold. Soft aluminum was used as the compliant medium. In contrast, the method of the subject invention is directed to effecting structural bonds between strong structural alloys capable of carrying in excess of a ton of load in shear and uses 4000 watts to effect the weld. The soft compliant materials taught by Coucoulas are substantially different from the hard, non-compliant shims used in the present invention. Against the foregoing background, it is a primary object other present invention to provide a method for preventing tip sticking during welding operations. It is another object of the present invention to provide a method of maintaining power tips and anvils free of material pick-up from the workpieces. It is yet another object of the present invention to provide such a method particularly adapted for use in association with ultrasonic or vibratory welding equipment. It is still another object of the present invention to provide such a method which may be used in a production environment and which does not deleteriously affect the quality of the resultant weld. It is yet still another object of the present invention to provide such a method which is relatively inexpensive and which may be used in a production environment. It is still yet another object of the present invention to provide apparatus for effecting such methods. BRIEF SUMMARY OF THE INVENTION The present invention, in brief summary, comprises a method for preventing tip sticking during the ultrasonic vibratory spot welding of workpieces. The ultrasonic welder used includes a welding tip and a complimentary anvil which define a throat into which the workpieces to be welded may be inserted. The welding tip is adapted to introduce into and through the workpieces high frequency vibratory energy in order to effect a bond therebetween. Shim material is inserted between the welding tip and the workpieces and/or between the anvil and the workpieces, said shim material having a hardness greater than the hardness of the workpieces. After insertion of the shim material, ultrasonic vibratory energy is then introduced through the shim material and the workpieces and bonds are effected therebetween. The shim material may then be peeled away and discarded. Apparatus for effecting this method is further provided. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and still other objects and advantages of the present invention will be more apparent from the detailed explanation of the preferred embodiment of the invention in connection with the accompanying drawings wherein: FIG. 1 is a perspective view of an ultrasonic vibratory welder which includes the tip sticking preventing apparatus of the subject invention; FIG. 2 is an enlarged front view illustrating the weld zone of FIG. 1 during an actual welding operation; FIG. 3 is a sectional view taken along line 3--3 of FIG. 2; and FIG. 4 is an enlarged front view illustrating the weld zone of an alternative embodiment of the subject invention. DETAILED DESCRIPTION OF THE INVENTION An ultrasonic spot welding machine capable of welding together structural metal sheets, referred to generally by reference numeral 10, is illustrated in side perspective view in FIG. 1. Ultrasonic spot welder 10 includes a generally C-shaped clamping frame 12 pivotably mounted about pivot 14 and supported on a stationary central welder frame 16. Clamping frame 12 includes elongated upper and lower sections 12A and 12B, respectively, which, in combination with the central welder frame 16, define a throat T into which the workpieces to be welded may be inserted for welding. A welding head 20, including a welding tip 21, which forms the end of a vibratory reed 22, is provided and is secured to stationary welder frame 16. A slideably mounted anvil 40 is provided on the opposite side of the throat. Collar clamps 50 and 60 are provided about the anvil 40 and the welding tip 21, respectively. Anvil 40, which is movable toward and away from welding tip 21 along anvil guide 44, is powered by at least one internally contained, hydraulic anvil cylinder contained with cylinder head 46. Movement of anvil 40 is independent of movement of collar clamp 50. When workpieces W1 and W2 to be welded (See FIGS. 2 and 3) are inserted into the throat between the anvil 40 and the welding tip 21, the anvil 40 is lowered in a clamping direction C toward welding tip 21 until, as shown in FIGS. 2-3, the workpieces are clamped together. This clamping action not only serves to clamp the workpieces together but, additionally, causes a compressive force to be applied between them. Spot welding of the workpieces may therefore be accomplished in the manner hereinafter described. Vibratory reed 22, at its end opposite the welding tip 21, is connected to a transducer which is contained within welding frame 16. The transducer transmits lateral vibrations and induces flexural vibration of the reed 22 so that the welding tip 21 at the upper end of the reed 22 may introduce shear vibrations into workpieces W1 and W2. The transducer consists of piezoelectric ceramic elements encased in a tension shell assembly and is operated at a nominal frequency of about 15 kHz. Spot welder 10, which is a modification of the Sonobond Model M-8000 ultrasonic spot welder, includes a frequency converter which incorporates a wide-band RF power measuring circuit for sampling the output power to detect the forward power and the load power based on the principle of directional coupling in a transmission line. The signal is processed electronically by internal circuitry to provide true RMS values which are displayed as either the forward power or the load power. Forward power is the output of the frequency converter delivered to the transducer in the welding tip 21 while load power is the transducer drive power that is acoustically absorbed in the weld zone. The difference between the forward power and the load power represents the reflected power induced by the load impedance mismatch and is minimized during subsequent welding operations by impedance matching techniques. Welding tip 21 and anvil 40 are both fabricated from a generally hard metal such as, for example, steel hardened to about R c 50. The radii of the welding tip 21 may be between about 2" and about 20" and the shape and dimension of anvil 40 generally conforms to that of the welding tip 21. As previously stated, the subject invention resides in a method of inserting shim material between welding tip 21 and one of the workpieces W1 to be welded and/or between anvil 40 and the other workpiece W2. Such a method has been found to substantially reduce or eliminate tip sticking which had, heretofore, resulted in the hardened welding tip 21 becoming smeared with the softer material of the workpiece W1. Workpiece W1 is typically stainless steel or aluminum or titanium alloys. As shown in FIG. 2, shim material 105 is inserted directly between the welding tip 21 and the lower workpiece W1 which is to be ultrasonically welded to upper workpiece W2. During the welding operation, the high frequency energy passes from the welding tip 21 through the shim material 105 and into the workpiece W1 and W2 which are held together by the compressive forces generated between welding tip 21 and anvil 40 as anvil 40 is moved in clamping direction C toward welding tip 21. The high frequency vibratory energy generated from welding tip 21 in combination with these compressive forces causes a spot weld S, as shown in FIG. 3, to be effected therebetween. The shim material 105 used may be any metal, the hardness of which is greater than the hardness of the workpieces W1 and W2 being welded together so as to cause minimal bonding between the shim material 105 and the welding tip 21 or between the shim material 105 and workpiece W1. A strong bond however occurs between the softer workpieces W1 and W2. Optimal choices of shim materials 105 and the respective thicknesses thereof are dictated by cost as well as physical requirements, i.e., having limited deformability, ability to develop a minimal bond with the other elements, fatigue resistance, having no inclination to induce corrosion in the workpiece, etc. Particularly good results have been obtained when the shim material used is nichrome, brass, hardened beryllium copper, Inconel, tempered carbon steel, tempered carbon steel having a blue oxide coating and 15-5 pH alloy. Similarly, thickness of the shim material may vary widely depending on application although it is preferred that the thickness of the shim material be between about 0.002" and 0.010" and, most preferably, between about 0.003" and about 0.005". As shown in FIG. 2, the shim material 105 is inserted directly between the welding tip 21 and the lower of the workpieces being welded together which results in a weld being effected between the shim material 105 and the two workpieces W1 and W2. After completion of welding because the shim material 105 is a relatively hard material, there tends to be little or no smearing or adherence of the shim material 105 on the welding tip 21. Additionally, because the shim material 105 is generally harder than the workpieces being welded, the bond between the shim material 105 and workpiece W1 has a very low tensile strength and is peel sensitive. Power transmission, which is in a shear mode, is not inhibited by the shim material 105 while peel strength, which is tensile mode dependent, is very low. As such, the shim material 105 tends to be easily separated from the workpieces W thus leaving the workpieces strongly bonded together. FIG. 4 is illustrative of an alternative embodiment of the subject invention in which shim material is inserted both between the welding tip 21 and lower workpiece W1 and between the anvil 40 and the upper workiece W2. Such an arrangement prevents tip sticking between both the anvil 40 and the workpieces as well as between the welding tip 21 and the workpieces. The manner in which the shim material 105 is inserted between the welding tip 21 and the lower workpiece W1, as in FIG. 2 or between both the welding tip 21 and the lower workpiece W1 and between the anvil 40 and the upper workpiece W2, as in FIG. 4, may vary depending upon the specific applications desired. A particularly preferred method of inserting the shim material 105 between the lower workpiece W1 and the welding tip 21 is illustrated in FIG. 1 wherein a continuous feed roll of shim material 105 is mounted on a rotatable bracket horizontally positioned on one side of the clamping frame 12 of the welder 10 (not shown). The shim material 105, which comes off this feed roll, is directed over welding tip 21, guided around guide 52 and is then wound around and collected by take-up roll 54 mounted on bracket 55. Take-up roll 54 is adapted to rotate in a clockwise direction, and is driven by motor 56. As take-up roll 54 rotates, it causes shim material 105 drawn from feed roll (not shown) to pass across the welding tip 21 and be collected on take-up roll 54. In this manner, motor 56 may be coordinated with the welding sequence of welder 10 so as to sequentially index shim material only after a weld is effected rather than continuously draw shim material 105 over the welding tip 21. This insures that fresh shim material 105 will always be positioned between the welding tip 21 and the workpieces W1 but none will be wasted. Use of fresh shim material is important to the objective of obtaining welds with repeatable properties; repeated use of shims spots on different welds would lead to the accumulation of welding debris and thereby cause progressive alteration of weld properties. Feed roll (not shown) is mounted on the clamping frame 12 of the welder 10 in the same manner as take-up roll 54 and a complimentary guide (not shown) may also be provided, if desired, on the feed side of the welder 10 in order to guide the shim material 105 from the feed roll (not shown). It will, of course, be appreciated that the subject method and apparatus are not limited exclusively for use in association with ultrasonic vibratory welding equipment but may also be used in association with resistance spot welding procedures wherein thermal energy is emitted from its welding tip to effect welding of the workpieces. Periodically, resistance spot welds in a production environment must be shut down for cleaning and reshaping of the welding tips. Depending upon the particular parts being welded and the permissible quality of the resultant welds, tip cleaning must be done after between 5 and about 25 welds. Under certain conditions and where certain agents are applied to exterior surfaces, up to 50 or 60 welds may be effected before cleaning is required. The method and apparatus of the subject invention may therefore be utilized in that environment. To demonstrate the effectiveness of the subject method and apparatus, trials were conducted using shims of 0.005" thick beryllium/copper when welding together using a resistance spot welder sheets of 2024-T3 alclad which were 0.025" thick. Copper based shim material was used since it acts as a conductor similar in character to the welder tip material and would have no deleterious affect relative to current flow. These trials demonstrated that welding occurred in a natural way with some aluminum being transferred to the shim material where it was carried away before subsequent welding. Subsequent trials on sheets of 2024-T3 alclad, which were 0.050" thick, resulted in good repeatable welds with no build-up or alteration of the welding tip surface. These trials demonstrate that such method and apparatus can similarly be used with resistance spot welding apparatus which would eliminate the necessity for repeated cleaning of the welding tip which can result in a savings of from one-half to three-quarters of the time required to make resistance welded assemblies. Having thus described the invention with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made thereon without departing from the spirit and scope of the invention as defined by the appended claims.	A method is provided for preventing tip sticking during the spot welding of workpieces including ultrasonic vibratory spot welding. The welding apparatus includes a welding tip and a complimentary anvil between which the workpieces to be welded may be inserted. The welding tip is adapted to introduce into and through the workpieces sufficient amounts of energy to effect a weld between the workpieces. Shim material is inserted between the welding tip and the workpieces and/or between the anvil and the workpieces, said shim material having a hardness greater than the hardness of the workpieces. After insertion of the shim material, welding energy is then introduced through the shim material and the workpieces and welds are effected therebetween. The shim material is then torn away and discarded. Apparatus for effecting this method is further provided.	1
This application is a Continuation of prior application No.: Ser. No. 10/100,960 filed on Mar. 18, 2002, now U.S. Pat. No. 6,771,458. TECHNICAL FIELD This invention relates to enclosures in a disk drive providing a reduced air gap around disk drive media surfaces within the enclosure. BACKGROUND ART Disk drives are an important data storage technology, which include several crucial components. Disk drive read-write heads directly communicate with a disk surface containing the data storage medium over a track on the disk surface. This invention involves improving the ability to position at least one read-write head over the track on the disk surface. FIG. 1A illustrates a typical prior art high capacity disk drive 10 including actuator arm 30 with voice coil 32 , actuator axis 40 , suspension or head arms 50 – 58 with slider/head unit 60 placed among the disks 12 . FIG. 1B illustrates a typical prior art high capacity disk drive 10 with actuator 20 including actuator arm 30 with voice coil 32 , actuator axis 40 , head arms 50 – 56 and slider/head units 60 – 66 with all but one disk 12 removed as well as including spindle motor 80 . Since the 1980's, high capacity disk drives 10 have used voice coil actuators 20 – 66 to position their read-write heads over specific tracks. The heads are mounted on head sliders 60 – 66 , which float a small distance off the disk drive surface when in operation. Often there is one head per head slider for a given disk drive surface. There are usually multiple heads in a single disk drive, but for economic reasons, usually only one voice coil actuator. Voice coil actuators are further composed of a fixed magnet actuator 20 interacting with a time varying electromagnetic field induced by voice coil 32 to provide a lever action via actuator axis 40 . The lever action acts to move head arms 50 – 56 positioning head slider units 60 – 66 over specific tracks with speed and accuracy. Actuator arms 30 are often considered to include voice coil 32 , actuator axis 40 , head arms 50 – 56 and head sliders 60 – 66 . Note that actuator arms 30 may have as few as a single head arm 50 . Note also that a single head arm 52 may connect with two head sliders 62 and 64 . Today, read-write head positioning errors are a significant point of failure and performance degradation. These positioning errors are caused in part by disk fluttering. Some fluttering problems for disks can be attributed to instabilities in the motor turning the disk, which are being addressed by the motor manufacturers. The disk drive industry faces some significant challenges. As either recording densities or spindle speed increases, both head positioning accuracy and head-flying stability must increase. Note that competitiveness in the disk drive industry requires both requires both increased recording density and increased spindle speeds. Note that head-flying is the motion of the read-write head over the disk surface, which flies a short distance off that surface. In order to achieve an even higher track density essential for meeting the higher recording density requirements, the allowable position error of the heads relative to registered data tracks is required to be less than 0.05 μm for the next few years. New ways to improve head positioning and stabilize head-flying are needed to meet these challenges, as well as improve the reliability of existing disk drives. SUMMARY OF THE INVENTION The inventors have found that the above needs can be achieved through further reduction of disk fluttering and flow-induced vibration around actuator arms. High-speed rotation results in large amplitude vibration of the head-slider suspension and the arms. Thus the reduction of flow-induced vibration is essential to current and future disk drive to protect head-positioning failures. Aerodynamics has been an area of active and continuing research since at least the nineteenth century. Prandtl defined boundary layers early in the twentieth century. The boundary layer concept was directly applicable to fluid flows involving air, water and other low viscosity fluids. The boundary layer is a fluid region near a surface with essentially no relative velocity with regards to that surface. This region is caused by the effect of friction between the solid surface and the fluid. The depth of this region is roughly proportional to the square root of the viscosity divided by the velocity of the surface. The inventors have discovered that aerodynamic forces contribute to disk fluttering. If the flow of air about these disk surfaces is unstable, the resulting aerodynamic forces can mechanically excite the disk surfaces, causing fluttering. These aerodynamic forces act upon disk surfaces with respect to the air cavity in which the disk surfaces rotate. A rotating disk surface will tend to create a rotating boundary layer of air. This boundary layer will tend to rotate in parallel to the motion of the disk surface. The stationary surface of the disk drive cavity facing the disk surface will also tend to generate a boundary layer. The inventors discovered that when there is enough distance between the stationary surface and the disk surface for more than the boundary layer of the rotating disk surface, there is a back flow created against the direction of flow from the rotating disk surface. The inventors have discovered that a significant reduction in disk surface mechanical fluttering results from reducing the air gap between stationary surfaces facing the disk surface to about the boundary layer thickness. The inventors have found that when the air gaps are approximately the boundary layer thickness, there is improved head positioning. When the air gaps are smaller fractions of the boundary layer thickness, there are further improvements in head positioning. These improvements are summarized for an operational rotating velocity of 5400 Revolutions Per Minute (RPM) in FIG. 3 . Similar improvements are expected for other operating rotational velocities such as 7200 RPM, 10,000 RPM and over 14,000 RPM. The invention includes not only the mechanical enclosures housing disk surfaces within a disk drive, but also the manufacturing methods, and the resulting disk drives. The disk drives may further be at most 13 millimeters in height. These and other advantages of the present invention will become apparent upon reading the following detailed descriptions and studying the various figures of the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A illustrates a typical prior art high capacity disk drive 10 including actuator arm 30 with voice coil 32 , actuator axis 40 , suspension or head arms 50 – 58 with slider/head unit 60 placed among the disks 12 ; FIG. 1B illustrates a typical prior art high capacity disk drive 10 with actuator 20 including actuator arm 30 with voice coil 32 , actuator axis 40 , head arms 50 – 56 and slider/head units 60 – 66 with all but one disk 12 removed as well as including spindle motor 80 ; FIG. 2A illustrates a cross section view of spindle motor 80 and one disk 12 with air flow between the upper disk surface 12 and top disk cavity face, as well as air flow between the lower disk surface 12 and bottom disk cavity face; FIG. 2B illustrates the air flow situation between the upper disk surface 12 and top disk cavity face of FIG. 2A showing the formation of two separate boundary layers; FIG. 2C illustrates the air flow situation between the lower disk surface 12 and bottom disk cavity face of FIG. 2A showing the formation of only one boundary layer; FIG. 3 illustrates the relationship between the gap measured in millimeters along the horizontal axis and head positioning errors as a function of the gap for a disk surface rotating at 5400 RPM; FIG. 4 illustrates an exploded schematic view of a thin disk drive 10 using a single head and supporting various aspects of the invention; FIG. 5 illustrates a top schematic view of the thin disk drive 10 using the single head as illustrated in FIG. 4 ; FIG. 6A illustrates a perspective view of voice coil actuator components 32 , 40 , 50 , and 60 , assembled with respect to the disk drive base 110 as illustrated in FIGS. 4 and 5 ; and FIG. 6B illustrates a perspective view the assembled disk base 100 , spindle motor 80 , disk 12 , disk clamp 82 , and disk drive cover 110 , of FIGS. 4 and 5 . DETAILED DESCRIPTION OF THE INVENTION FIG. 2A illustrates a cross section view of spindle motor 80 and one disk 12 with air flow between the upper disk surface 12 and top disk cavity face, as well as air flow between the lower disk surface 12 and bottom disk cavity face. A qualitative description of air flow about a disk surface 12 is as follows. Because of the no-slip condition, fluid in contact with the surface rotates with the same angular velocity as the surface and experiences the same centripetal acceleration. At the start of motion, a boundary layer begins to form in the circumferential direction. Fluid in the boundary layer begins to spin but cannot maintain the same centripetal acceleration as the surface. It acquires an outward radial component. As the radial component increases in magnitude, a secondary layer develops in the radial direction with stresses centrally directed. These stresses exert an excitation force on rotating disk leading to the disk fluttering which impairs head-flying over that disk surface. FIG. 2B illustrates the air flow situation between the upper disk surface 12 and top disk cavity face of FIG. 2A showing the formation of two separate boundary layers. In a conventional hard disk drive, the flow pattern has secondary flows, radially outward near the disk 202 and inward at the housing 200 , which dominate the air flow. They are connected by axial flows near the periphery and near the axle. When the gap 190 between disk and cover/base is even larger than that of boundary layer thickness, a significant quantity of fluid in the interior region is essentially isolated from the main flow. It rotates approximately as a rigid body at one-half the angular velocity of the disk. These flow characteristics make large vortex and accelerate disk-tilting effect, which results in a severe Position Error Signal (PES) problem. It should be noted that in situations involving radial surface motion, the boundary layer is often formulated as proportional to the square root of the viscosity divided by radial velocity in radians per sec. TABLE 1 illustrates the boundary layer thickness to Revolutions Per Minute (RPM). RPM Boundary Layer Thickness (mm) 5400 0.7 7200 0.55 10,000 0.45 FIG. 2B reveals a large vortex over the area of the top disk of a disk stack, which may have just one disk. This vortex provides a mechanical force acting to excite disk fluttering. This is the situation found in all hard disk drives the inventors are aware of. The inventors found that removing this large vortex in the area of top disk improves the mechanical situation. Near the rotating disk surface, toward its rim, air flow velocities close nearing 10 meters (m) per second (sec) have been found in simulations. At the edge of the boundary layer, about one boundary layer thickness from the disk surface, air velocity is about 0. Further from the disk surface, a back flow forms due to the friction with the stationary surface. FIG. 2C illustrates the air flow situation between the lower disk surface 12 and bottom disk cavity face of FIG. 2A showing the formation of only one boundary layer. By making the gap 190 too narrow for secondary flows to exist as illustrated in FIG. 2C , the fluid adopts a Couette flow pattern 204 with a nearly straight-line, tangential velocity profile between the housing and the disk. FIG. 3 illustrates the relationship between the gap measured in millimeters along the horizontal axis and head positioning errors as a function of the gap for a disk surface rotating at 5400 RPM. The vertical axis is a percentage scale, with 100% being the current head position error rates with contemporary gaps of about 1.2 mm. When the gap is made less than the boundary layer thickness of 0.7 mm, errors in head positioning are about 75% compared to conventional error rates. Note that when the gap is about 0.4 mm, the head positioning errors are 50% of conventional rates. FIGS. 4 to 6B illustrate various schematic views a thin disk drive 10 using a single head and supporting various aspects of the invention. Note that a thin disk drive may be preferred in certain applications, such as multi-media entertainment centers and set-top boxes. Note that the thin disk drive using only a single head may further be preferred, allowing further reduction in the gap between the base 100 and the disk surface 12 . The use of a single head in the thin disk drive aids in reducing manufacturing costs and increasing manufacturing reliability. FIG. 4 illustrates an exploded schematic view of a thin disk drive 10 using a single head and supporting various aspects of the invention. Disk drive 10 includes a printed circuit board assembly 120 , a disk drive base 100 , a spindle motor 80 , a disk 12 , a voice coil actuator 30 , a disk clamp 82 and a disk drive cover 110 . Voice coil actuator 30 may further include a single read-write head on a head/slider 60 . Disk drive cover 110 may further include at least one region 112 providing a top stationary surface close to disk 12 upper surface. FIG. 5 illustrates a top schematic view of the thin disk drive 10 using the single head as illustrated in FIG. 4 . Note that region 112 may be essentially outside the region traveled by the actuator arm(s) 50 and head sliders 60 of voice coil actuator 30 when assembled and in normal operation. FIG. 6A illustrates a perspective view of voice coil actuator components 32 , 40 , 50 , and 60 , assembled with respect to the disk drive base 110 as illustrated in FIGS. 4 and 5 . FIG. 6B illustrates a perspective view the assembled disk base 100 , spindle motor 80 , disk 12 , disk clamp 82 , and disk drive cover 110 , of FIGS. 4 and 5 . The preceding embodiments have been provided by way of example and are not meant to constrain the scope of the following claims.	The inventors have discovered that aerodynamic forces contribute to disk fluttering. If the flow of air about these disk surfaces is unstable, the resulting aerodynamic forces can mechanically excite the disk surfaces, causing fluttering. The invention includes media enclosures constraining such aerodynamic effects, methods of making disk drives with these enclosures, the disk drives. This includes disk drives of at most 13 millimeters in height.	6
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is the national stage commencement under 35 U.S.C. 371 of international application number PCT/GB02/04050 filed 6 Sep. 2002, claiming priority to application number GB 0121655.5 filed 7 Sep. 2001. BACKGROUND OF INVENTION [0002] This invention relates to a resilient elastomeric structure. In particular, but not exclusively, it relates to a resilient elastomeric structure for use as a component of a playground toy or an amusement ride. [0003] In children's playgrounds, it is common to find rides that take the form of a ride body upon which a child can sit, the ride body being connected through a helical spring to a plate secured on the ground. This means that a child can sit upon the body and bounce or rock, causing the spring to flex. The resilient nature of the spring is such that it tends always to urge the ride body back to a neutral, upright position. To add interest to the ride, the ride body is typically shaped to resemble an animal, a motorcycle, or some other shape intended to please a child. [0004] These rides are popular with children, and are very safe, there being no instances known to the applicant of a child being harmed when playing on them, other than in the type of minor falls that will happen inevitably. However, the presence of a strong steel spring can give the ride an “engineered” appearance and the impression, even if incorrect, that the spring could injure a child, perhaps by trapping a hand or foot. [0005] It has been proposed in U.S. Pat. No. 5,415,590 to replace the spring in such a ride with a dome-shaped construction of natural and neoprene rubber, into which is moulded a steel support post, the body of the ride being carried on the support post. While such a ride may perform well when it is first manufactured, experience has shown that rubber will, over time, become brittle when exposed to the weather. When this happens, it looses its elastomeric properties, and may eventually become brittle. It is also possible that the supporting post will become loose or may even detach, this being highly undesirable and risky for a child using the ride. SUMMARY OF INVENTION [0006] An aim of this invention is to provide a replacement for the spring in a playground ride or other amusement apparatus that does not suffer from the disadvantages of the arrangement shown in U.S. Pat. No. 5,415,590. [0007] From a first aspect, this invention provides a resilient elastomeric support structure for use in a ride comprising an elastomeric body that includes a first connection formation for connection with a supporting foundation, a second connection formation for connection with a ride body, and a connection region interconnecting the first and second connection formations, the elastomeric structure being formed of polyurethane. [0008] It has been found that polyurethane exhibits particularly advantageous elastomeric properties while having greater durability and predictability of properties than can be obtained from rubber. These can be further enhanced by addition of an ultraviolet stabilising formulation. The resilient properties of polyurethane are exploited for some applications, such as bushes for use in vehicle suspension systems, where the main mode of deflection of the material is torsional. However, it has not recognised as being generally applicable in circumstances in which an elastomer is required. In particular, its use as a bulk material to be loaded as a strut, with a mode of deflection in compression and in flexion is not usual. [0009] In preferred embodiments, the elastomeric body may be formed as a one-piece moulding. [0010] A connection formation of preferred embodiments of the invention may include a securing region, such as a flange formed in the elastomeric body. The securing region typically includes one or more securing formations that can interact with fasteners to secure the elastomeric structure to a supporting foundation or to a ride body, as the case may be. For example, the securing formations may include holes, through each of which a fastener, such as a bolt, can be passed. [0011] It has been found that the resilient properties of polyurethane can present difficulties when a body of it is to be secured, for example by means of bolts. The material can deform to such an extent that the head of the bolt can be pulled through a hole made for the shaft of the bolt, in many cases, without causing any damage to the structure of the body. Most preferably, the securing region is disposed such that material of the elastomeric body is held substantially in compression by a fastener. This can help to resist undesirable distortion or tearing of the elastomeric material. Additionally, in preferred embodiments of this invention, the elastomeric structure includes a respective reinforcement member provided as part of each connection formation. For example, a reinforcement member may include an annular element, typically of metal, that lies on or adjacent to a flange that is formed integrally with the elastomeric body, and which, in use, can hold the flange in compression. For example, the annular element may be placed upon the flange or moulded within it. [0012] The elastomeric body may advantageously be covered with a defensive cover to protect it against damage or attack. A cover of chain mail has been found to be highly effective yet sufficiently flexible to move with the elastomeric body. [0013] In embodiments of the invention, the elastomeric body may be formed integrally with a ride body. For example, the elastomeric body and the ride body may be formed as a single moulding. [0014] From a second aspect, this invention provides an amusement ride comprising a ride body and one or more elastomeric structures, each embodying the first aspect of the invention, upon which the ride body can be supported. [0015] A first, and most usual type of amusement ride has a body that is supported on a single support structure such that it can rock laterally and/or bounce vertically (so-called “rock and ride”). Such a ride is most normally configured such that a rider or riders can sit upon the ride body. [0016] Alternatively, the ride body can be supported upon two spaced supporting members. This can allow a designer to control the axes about which the body can rock. In one configuration of such an embodiment, the ride body may be configured to allow one or more riders to stand upon it. [0017] In embodiments of this aspect of the invention, the ride body and the elastomeric body may conveniently be formed as a single moulding of polyurethane. This avoids the need to make and connect separate components for the elastomeric body and the ride body. Regions of the ride body with which a rider makes direct contact may be integrally skin foamed. This provides a soft, spongy and grippy surface in the foamed region. The foamed regions can be formed in one moulding with non-foamed regions, yet their surface appearance is similar to that of the regions that are not foamed. Alternatively, the elastomeric body can be formed from several mouldings interconnected, for example, by adhesives. It has been found that the mouldings can be interconnected by cyanoacrylate adhesive (particularly suitable in regions of comparatively low flexure) or by solvent welding, which allows for greater flexibility in the region of the joint. [0018] An amusement ride may have components formed as additional mouldings or rigid or flexible material. These may be co-moulded with the polyurethane moulding of the ride body. This has the effect of covering the additional components with a coating of polyurethane. Components of other materials can also be provided. For example, the ride body may be provided with components of metal. Such components can also be co-moulded with the polyurethane ride body so that they appear to be integral with the ride body. It may be particularly advantageous to foam the polyurethane in the region of the additional components to cushion and protect them. [0019] There is almost an unlimited range of shapes that can be selected by a designer for the ride body. These will typically be selected as to appeal to children of an age by which the ride is intended to be used. For example, they may include representations of animals, birds, plants, machinery such as cars or rockets, amongst many other possibilities. These designs may be anthropomorphised, for example by the addition of features that resemble facial features. BRIEF DESCRIPTION OF DRAWINGS [0020] [0020]FIG. 1 shows an amusement ride being a first embodiment of the invention; [0021] [0021]FIG. 2 shows an elastomeric structure for use in the embodiment of FIG. 1; [0022] FIGS. 3 to 8 respectively show rides being second to seventh embodiments of the invention; [0023] [0023]FIG. 9 shows the embodiment of FIG. 7 in use; [0024] [0024]FIG. 10 is a sectional view of an embodiment of the invention showing means by which it may be fixed upon a supporting surface; and [0025] [0025]FIG. 11 shows an alternative fixing arrangement of the embodiment of FIG. 1. DETAILED DESCRIPTION [0026] Embodiments of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings. [0027] With reference first to FIG. 1, an amusement ride embodying the second aspect of the invention comprises a ride body 10 , and a support structure 12 . [0028] The ride body 10 is formed as a moulding of hard plastic, shaped, in this embodiment, to resemble a motorcycle. The body 10 has a seat portion 14 upon which an individual (typically, a child) can sit. (Alternative embodiments may have space to carry more than one person.) The ride body can be substantially conventional in construction. Indeed, it may be a ride body primarily intended for use with a conventional steel coil spring support, in this embodiment, used instead with an elastomeric support in accordance with the invention. [0029] The support structure 12 is in constructed as an embodiment of the first aspect of the invention. The support structure comprises an elastomeric body 20 that is formed as a one-piece moulding of polyurethane to which an ultraviolet stabilising formation has been added. The elastomeric body is rotationally symmetrical about an axis A that is vertical in normal use, and symmetrical about a middle plane B that is normal to the axis A. [0030] The elastomeric body has upper and lower regions 22 that are mirror images of one another, disposed about the middle plane B. A generally cylindrical trunk portion 24 interconnects the upper and lower regions 22 ; the trunk portion 24 being coaxial with the axis A, and having an axial bore 26 . The upper and lower regions 22 are of diameter greater than that of the trunk portion, and extend form it in a bell-like shape. Within each of the upper and lower end regions 22 a void 28 is formed, the size and shape of which is selected to confer required elastic properties upon the end region, and to reduce the amount of material required to mould the elastomeric body 20 . [0031] The axial bore 26 serves to control the elastomeric properties of the elastomeric body 20 . Increasing the diameter of the bore increases the flexibility of the body. Moreover, the bore 26 need not be of circular cross-section; that is to say, it may be of non-constant diameter. In this case, the flexibility of the body can be controlled such that its flexibility is different in different directions. The bore 26 may be omitted altogether to maximise the stiffness of the body 20 . [0032] In an alternative configuration, a tension element, such as a metal tube or a bolt, can pass through the bore to connect upper and lower regions of the support structure. This can limit movement of the support structure and/or strengthen it. Such a tension element will normally be mounted at its lower end to permit some pivotal movement. [0033] Note also that the elastomeric body need not be of circular diameter. Again, this can be used to control the stiffness of the elastomeric body in different directions. [0034] Each of the end regions 22 carries a flange 30 extending around its periphery, and projecting radially. The flange 30 of the lower and upper end regions is part, respectively, of a first and second connection region of the support structure. The flange has a plurality of holes 32 formed though it, the holes 32 being parallel to the axis A and spaced regularly about the flange 30 . These holes 32 act as securing formations, each for receiving a fastener, as will be described below. [0035] Each connection region further includes a reinforcement member. The reinforcement member in this embodiment is an annular metal ring 42 that lies in contact with the flange 30 . The ring 42 has a mean diameter substantially the same as that of the flange 30 and has through holes 44 that align with the holes 32 in the flange 30 . [0036] The first connection region serves to anchor the support structure 12 to a foundation, in this case, a concrete base 46 . To this end, the first connection region comprises an anchor plate 50 that is secured within the base 46 . The anchor plate 50 has a plurality of tapped holes 52 that are positioned to correspond with the holes in the flange 30 and the ring 42 . The support structure 12 is connected to the anchor plate 50 by bolts 54 that pass through the holes 44 in the ring 42 and the holes 32 in the flange 30 to be threaded into the tapped holes 52 in the anchor plate 50 . A tubular spacer (not shown) may be provided surrounding the bolt to limit the extent to which the bolts 54 can be driven into the concrete base 46 . The length of the spacer can be selected such that the flange 30 is securely fastened but the material of the flange cannot be compressed excessively. The spacer may be implemented as part of the ring 42 , within the flange 30 or as separate components. [0037] Alternatively, the ring can be omitted, and each bolt may be surrounded by a spacer 60 component as shown in FIG. 11. The spacer component comprises a metal tube that passes through the holes 44 in the flange 39 . Secured to (or separate from) an upper end of the tube is a washer. The shaft of the bolt 54 passes through the tube into the base 46 . The head of the bolt bears against the washer to clamp the flange to the base 46 . The length of the tube may be substantially equal to the thickness of the flange 30 , or it may be shorter to apply a clamping force to the flange while preventing excessive distortion of the flange. [0038] The second connection region is similarly constructed, except that the anchor plate 50 ′ is, in this case, moulded within the ride body 10 . The ride body 10 is secured to the support structure 12 by bolts 54 ′ that pass through the corresponding ring 42 ′ and flange 30 ′. [0039] When a child sits on the seat portion 14 , his or her weight causes the elastomeric body 20 of the support structure 12 to compress resiliently, the trunk portion 24 acting as a springy compressive strut, allowing the child to bounce up and down. When the child rocks side-to-side, or forwards and backwards, the trunk portion 24 flexes resiliently, for example, by up to as much as 125 always tending to restore itself to a straight configuration. Therefore, from the point of view of the child, the support structure has much the same properties as a metal spring. However, the external appearance of the support structure 12 is almost smooth, and has no formation or structure that might actually present a risk or even give the impression of presenting a risk to a child. [0040] As an enhancement to this embodiment, it is possible to cover the elastomeric body with a protective cover. One particularly advantageous type of cover is formed of a metal mesh, having an appearance much like chain mail. This can provide a very strong cover that is resistant to damage and malicious attack, yet which is sufficiently flexible to accommodate movement of the elastomeric body 20 . [0041] In further embodiments of the invention, the use of polyurethane can be extended to the ride body 10 . [0042] In the embodiments of FIGS. 3 and 4, the rides are formed, respectively, to resemble an anthropomorphised toadstool and drinking cup. The ride bodies 310 , 410 are constituted by portions formed to resemble a toadstool cap and a teacup. In each case, the ride body is supported on an elastomeric body 320 , 420 that operates and is constructed in accordance with the principled described above, but which has an outer surface decorated to provide an appearance that fits in with the design of the ride as a whole. So, in the case of the embodiment of FIG. 3, the elastomeric body 320 is naturally formed to resemble a toadstool stem. In the embodiment of FIG. 4, as will be seen, the shape of the elastomeric body 410 is more fanciful. [0043] Both of these embodiments can conveniently be formed from a single moulding of polyurethane to make up both the ride body and the elastomeric body. In the region of the ride body 310 , 410 , the polyurethane may be integrally skin foamed or solid, as required. [0044] As can be seen in cross-section in FIG. 10, the ride body 310 is secured to a foundation, such as a concrete base 346 , at a flange portion 330 by a metal ring 344 and bolts 354 . [0045] The embodiment of FIG. 5 also has a ride body 510 and an elastomeric body. In this case, the ride body 510 is shaped to resemble an anthropomorphised rocket, with the elastomeric body being constituted by a portion that represents the rocket's exhaust. The ride body 10 is formed with an elongate cylindrical portion that has an axis at approximately 45° to the horizontal. The elastomeric body 520 connects a lower end portion of cylindrical portion to a base flange 530 secured to a support surface, such as the ground. Between the base flange 530 and the ride body 510 , the elastomeric body has a curved section that acts in flexion as a spring, whereby the ride body can move in a vertical plane, above and below its natural 45° position and side-to-side as the rider shifts his or her body weight. [0046] A metal loop 512 is moulded into the ride body 510 to form a loop that projects from the cylindrical portion. The metal loop 512 is covered by foamed polyurethane during the moulding process. A seat position 514 is defined upon the cylindrical portion of the ride body 510 to provide a safe and comfortable grip. A child sitting upon the seat portion can cause the ride body 510 to bounce in a vertical plane as permitted by flexure of the resilient body. [0047] The embodiments of FIGS. 6 and 7 are constructed upon principles similar to those of FIG. 5 in that the elastomeric body operates primarily in flexion. In the embodiment of FIG. 6, the ride body 610 is shaped to resemble a swan and the elastomeric body 620 is shaped to resemble the swan's legs. A seat portion 614 is formed by the swan's wings. The portion of the body the corresponds to the swan's wing may be elastomeric or substantially rigid. In FIG. 7, the ride body 710 is shaped as the body of a dolphin, and the elastomeric body 710 is its tail. Fins 716 of the dolphin serve as a grip and footrests around a seat portion 714 on the dolphin's back. Both of these embodiments are formed with the elastomeric body and the ride body as polyurethane mouldings, optionally being integrally foamed in regions of the body portion. Components may be moulded separately. For example, in the embodiment of FIG. 6, the swan's wings may be separate mouldings, and in FIG. 7, the dolphin's fins may be separate mouldings. These components can be co-moulded with the polyurethane or be of another plastic material. The rigidity of components such as the wings and fins in the above embodiment can be selected for a particular effect. They may be rigid to provide a firm grip, or may be flexible to add to the challenge of the ride. The embodiment of FIG. 7 is shown in use in FIG. 9. [0048] The embodiment of FIG. 8 provides a ride that can be used by several children at once. In this embodiment, the ride body 810 comprises a core with four radially projecting arms 816 , shaped to resemble the branches of a tree. Each of the arms 816 carries a polyurethane covered metal loop 812 to serve as a grip. A seat portion 814 is formed on each arm so that four children can be carried on the ride body 810 . The elastomeric body 820 is formed by the generally vertical trunk of the tree. Therefore, the children can cause the ride body 810 to rock from side to side, causing the elastomeric body 820 to flex along its length. [0049] In each case, the cross-sectional area of the elastomeric body varies along its length, having a greater area close to the ride body and to the portion at which it is connected to the ground, and an intermediate region of lesser cross-section. This allows a designer to select the amount of flexibility and the effective spring rate of the elastomeric body. It has been found that it is not essential to make the outer surface of the elastomeric body smooth in order to achieve the desired spring characteristics. Several different colours of material can be moulded together or other aesthetic elements such as metallic glitter can be added to the mould to enhance the appearance of the ride. Therefore, it is possible to incorporate decoration and components of the aesthetic design of the ride into the outer surface of the elastomeric body as part of the moulding process. [0050] Embodiments of the invention can be applied to replace a steel spring in many examples of “rock-and-ride” or “seesaw” rides, in a ride specifically designed for use with the invention, or to substitute a steel spring in an existing ride.	A resilient elastomeric support structure for use in a ride such as a playground rock and ride or a see-saw is disclosed. The support structure comprises an elastomeric body that includes a first connection formation for connection with a supporting foundation, a second connection formation for connection with a ride body, and a connection region interconnecting the first and second connection formations. The elastomeric structure is formed of polyurethane, preferably with an ultraviolet stabiliser, which has advantageous mechanical and elastic properties and which is durable.	0
FIELD OF THE INVENTION [0001] The present invention relates to a method and a device for evaluating and rearranging a cluster map of voxels in an image. BACKGROUND OF THE INVENTION [0002] Clustering algorithms allow the grouping of similar regions in an image. Clustering is usually achieved by defining regions, in which neighboring voxels have similar values. These voxels are then combined, forming a cluster, see D. L. Pham et al.: “Current Methods in Medical Imaging”, Annu. Rev. Biomed. Eng. 2000. 02:315-37. A cluster map therefore reduces the quasi-continuous values of the original image to a smaller number of levels, forming a cluster map. This is depicted in FIG. 1 showing an example of three cluster levels, cluster level A, B and C. The resulting maps can be displayed alone or overlaid over the original topographic data, see A. T. Agoston et al.: “Intensity-modulated parametric mapping for simultaneous display of rapid dynamic and high-spatial-resolution breast MR imaging data”, Imaging and Therapeutic Technology 21, 217, 2001. Cluster maps are used for various applications, one prominent and important example being radio therapy planning (RTP), see L. Xing et al.: “Inverse planning for functional image-guided intensity modulated radiation therapy”, Phys. Med. Biol. 47, 3567, 2002. [0003] Achieving a cluster map by a simple and basic clustering algorithm such as K-means algorithm usually results in fragmented clusters marked by the dotted circle in FIG. 1 101 , and isolated clusters 102 - 104 . [0004] In applications such as RTP, segmentation and isolation is a major problem. For effective dose planning it is necessary to reduce the number of cluster areas to a minimum, avoiding both segmented and isolated clusters. Several morphological segmentation algorithms exist to achieve this goal, such as “erosion” and “dilation”, distance transformation, see Milan Sonka and J. Michael Fitzpatrick: Handbook of Medical Imaging, Volume 2. FIG. 2 shows a “reduced cluster map”, resulting from the cluster map in FIG. 1 after appliance of suitable clustering algorithms. FIG. 2 contains only one single cluster level C resulting after merging of fragmented clusters 101 from FIG. 1 into a single cluster, and erasing the isolated clusters. [0005] Various approaches and algorithms exist to accomplish the described reduction of a cluster map, and therefore different results can be achieved. Since such a reduction of the cluster map always results in loss of initial image information, it is important to evaluate the executed modifications. Especially in the medical environment it is crucial to have access to a powerful and yet simple evaluation tool. On one side, therapy planning must not be based on misarranged cluster data, on the other side complicated methods will not find acceptance in a clinical environment. BRIEF DESCRIPTION OF THE INVENTION [0006] The object of the present invention is to improve prior art cluster reduction methods with regard to sub-cluster scatter by means of providing a method that enables influencing the clustering either manually or automatically. [0007] According to one aspect the present invention relates to a method of rearranging a cluster map of voxels in an image, the cluster map resulting from applying a clustering algorithm on the image, where the cluster map includes at least two cluster levels, the clustering algorithm further being arranged to determine the distribution of the voxels within the cluster map and to determine at least one boundary parameter that separates the distribution into at least two distribution domains, wherein each respective distribution domain reflects the distribution of the voxels of a single cluster level, the method comprising: providing an input value indicating at least one updated boundary parameter where the boundary parameter indicates an updated population of the distribution domains, and re-calculating the cluster levels in accordance to the updated population of the distribution domains. [0010] By varying the boundary parameter in that way the cluster boundary will also be changed and thereby it is possible to rearrange the cluster map. As an example, if 25% of the voxel distribution belongs to distribution domain A, 45% to distribution domain B and 30% to distribution domain C, and the result of these input values do not result in an acceptable cluster map, new input values can be provided. These input value can e.g. be 30% belonging to A, 40% belonging to B and 30% to C. Based on the updated population, the cluster levels are then re-calculated. This can be considered as an iteration method, since if the updated cluster map is still not acceptable, a new input value can be provided and the updated cluster map will be re-updated until the quality of the cluster map is acceptable. [0011] In an embodiment, the input value is provided by a user after evaluating the cluster map, where the evaluation is based on viewing the cluster map and the distribution of the voxels simultaneously. This enables the user to interactively monitor and influence the clustering and therefore easily evaluate whether the obtained cluster map is acceptable or not. [0012] In an embodiment, the input value is provided automatically after evaluating the cluster map. It follows that the sub-cluster scatter, i.e. the variance of e.g. the sub-cluster centers weighed with their size, will be minimized. This may possible include the morphological (growing/shrinking) operations. Such an automatic process can also be used in a combination with the interactive monitoring of the user. [0013] In an embodiment, the at least two cluster levels and distribution domains are characterized by different color components, wherein the same color component is used for a cluster level and the distribution domain reflecting the distribution of the voxels within the cluster level. Such a visualization allows easy and user friendly evaluation of the achieved clustering. [0014] In one embodiment, the distribution of the voxels within the cluster maps is a histogram. [0015] In another embodiment, the histogram bars further contain color components from the neighboring domains, and thereby voxels from the neighboring domains, such that a partial overlap between adjacent domains is obtained. It follows that a better clustering may be obtained since the histogram will not become as stepwise. [0016] In an embodiment, the applied clustering algorithm is a K-means algorithm, and wherein the updated population of the distribution domains results in updated cluster centers for each respective cluster level. When cluster algorithm such as K-means algorithm is implemented for computing the cluster map, the movement of the boundaries will cause a shift in the cluster center belonging to the clusters. Accordingly, the subsequent rearrangement of the cluster levels may in one embodiment comprise recalculating the cluster map based on the updated cluster centers. Typically, K-means algorithm runs in two steps, the first step being the step of estimating the cluster centers for each cluster level, where the cluster center is the average of all the voxels in the cluster, and the second step being the step where the actual cluster calculation is performed. In this second step the distance to the neighboring voxels is determined and based thereon it is evaluated which voxels belong to the same cluster level. Accordingly, in an embodiment, the step of rearranging the cluster levels in accordance to the updated population of the distribution domains comprises determining an updated cluster map based on the updated cluster centers, i.e. the second step includes an iteration of re-calculating the cluster levels. [0017] According to another aspect, the present invention relates to a computer program product for instructing a processing unit to execute the above method steps when the product is run on a computer. [0018] According to still another aspect, the present invention relates to a device for rearranging a cluster map of voxels in an image, the cluster map resulting from applying a clustering algorithm on the image, where the cluster map includes at least two cluster levels, the clustering algorithm further being arranged to determine the distribution of the voxels within the cluster map and to determine at least one boundary parameter that separates the distribution into at least two distribution domains, wherein each respective distribution domain reflects the distribution of the voxels of a single cluster level, the device comprising: an input means for receiving an input value indicating at least one updated boundary parameter where the boundary parameter indicates an updated population of the distribution domains, and a processor for re-calculating the cluster levels in accordance to the updated population of the distribution domains. [0021] The aspects of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS [0022] Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which [0023] FIG. 1 shows a typical cluster map with three cluster levels, [0024] FIG. 2 shows a reduced cluster resulting from FIG. 1 , [0025] FIG. 3 shows a flowchart illustrating an embodiment of a method according to the present invention, [0026] FIGS. 4 and 5 show an example of cluster map and a distribution of voxels, [0027] FIG. 6 shows an embodiment of applying a clustering algorithm, where the histogram bars in distribution of the domains can partly overlap, [0028] FIG. 7 shows an embodiment of a device according to the present invention for interactively evaluating and rearranging a cluster map of voxels in an image. DESCRIPTION OF EMBODIMENTS [0029] FIG. 3 shows a flowchart illustrating an embodiment of a method according to the present invention of interactively evaluating and rearranging a cluster map of voxels in an image. [0030] Such a cluster map is achieved by clustering algorithm such as K-means algorithm, QT Clust algorithm, Fuzzy c-means clustering algorithm, and other types of algorithms that have been reported in the literature, see Milan Sonka and J. Michael Fitzpatrick: Handbook of Medical Imaging, Volume 2. As mentioned previously in the background, achieving a cluster map by such algorithms usually results in fragmented clusters 105 shown within area 101 depicted in FIG. 1 , and isolated clusters 102 - 104 . The clusters shown in FIG. 1 are voxels that share some common trait, which typically is based on the proximity, i.e. a pre-defined distance measure. The areas marked as A, B and C are the cluster levels, where each cluster level is assigned to a particular color, e.g. A could be black, B could be blue and C could be red. [0031] As an example, if the K-means algorithm is applied on the image, the computation is divided into two steps. In the first step the voxels in the image are initially scanned and based thereon the centers for each cluster is calculated. In the second step the cluster centers are determined and based on a clustering parameter, in this case a distance parameter, the algorithm assigns each point to the cluster whose center is nearest. The cluster centers are then re computed, i.e. iteration is performed, until some convergence criterion is met. Typically, this is repeated until the assignment hasn't changed. [0032] As mentioned in the background, it is of great importance to reduce the number of cluster areas to a minimum for avoiding both segmented and isolated clusters and to solve this several morphological segmentation algorithms have been developed, as described in Milan Sonka and J. Michael Fitzpatrick: Handbook of Medical Imaging, Volume 2. FIG. 2 illustrates a result achieved by such segmentation algorithms, where only one single cluster level is obtained 201 , i.e. the segmented areas 105 belonging to the same cluster level have been combined together into one large cluster level, and the isolated clusters 102 - 104 have been eliminated. [0033] Referring to the flow chart in FIG. 3 , in the first step (S1) 301 the clustering algorithm is applied on the image. If the K-means algorithm is applied, it initially scans all the voxels in the image, determines the cluster centers and assigns each point to the cluster whose center is nearest, then re-computes the centers until the assignment hasn't changed. The result of the computation is accordingly the cluster map (e.g. as shown in FIG. 1 ) comprising two or more cluster levels. In the following, it will be assumed that the number of cluster levels is three, marked as A, B and C. Also, the result of the computation is a distribution of the voxels within each respective cluster level. An example of such a distribution is e.g. shown in FIG. 4 , where the distribution is divided into corresponding distribution domains 401 - 403 that are separated by boundary parameters 404 - 405 , where each distribution domains illustrated the distribution of the voxels for each respective cluster level. This will be discussed in more details later. [0034] In an embodiment, the resulting cluster map and the distribution of the voxels within the cluster levels are visualized simultaneously. This enables a user, which can e.g. be a technician or a doctor, to evaluate the quality of the clustering (S2) 303 . The result of such an evaluation could be that the user sees that the distribution is not reasonable. As an example, the result of the initial distribution could be that 20% of the voxels belong to cluster level A, 55% to cluster level B and 25% to cluster level C. [0035] The user can influence the distribution domains 401 - 403 by shifting the boundary parameters 404 - 405 (S3) 305 , and thereby affect the population of the voxels in the cluster levels, e.g. to 45% to cluster level B and 35% to cluster level C. This change in the boundary parameters may result in that new cluster centers (in the case a K-means algorithm is applied) are created. Therefore, new cluster centers are calculated and based thereon a new updated cluster mapping is determined (S4) 307 . [0036] In an embodiment, the cluster levels and the associated distribution domains 401 - 403 are displayed in the same color, which makes the evaluation step simpler and more user friendly. [0037] In another embodiment, the quality of the clustering is evaluated automatically by e.g. considering the variance in the clustering, wherein based on the automatic evaluation new boundary parameters or parameters are defined. This is preferable performed as an iteration unit e.g. so that the variance is below a pre-defined threshold value. [0038] FIGS. 4 and 5 show an example of cluster map 400 and a distribution of the voxels, which in this embodiment is a histogram 406 . In an embodiment, the cluster map 400 consists of three cluster levels, cluster level A 407 (that is e.g. associated with a black color), cluster level B 409 (that is e.g. associated with a blue color), and cluster level C 408 (that is e.g. associated with a red color). The histogram 406 shows the distribution for each cluster level, distribution domain 401 shows the distribution of the voxels in cluster level A, distribution domain 402 shows the distribution of the voxels in cluster level B and distribution domain 403 shows the distribution of the voxels in cluster level C. The boundary parameters 404 - 405 mark the threshold values for the clustering algorithm that is applied. Each histogram bar represents e.g. a certain color information value of the original image and its height indicates the number of voxels belonging to this grey value. [0039] In another embodiment, a cross wire 410 is used to provide a link between the cluster map 400 and the distribution 406 of the voxels within the cluster map 400 . Therefore, by moving the cross wire vie e.g. mouse function to cluster level C the arrow 411 will follow and simultaneously point to the histogram bar that has the same color information value. [0040] Accordingly, by e.g. displaying the cluster map and simultaneously the distribution of the voxels for a user, the user can easily evaluate whether the cluster map is acceptable or not. This would typically be based on the experience of the user. [0041] FIG. 5 illustrates a possible effect by moving boundary parameter 405 towards the right, e.g. via mouse click or selecting a new horizontal coordinate value, thereby enhancing the population of the voxels belonging to cluster level B 409 and reducing the population of the voxels belonging to cluster level C 408 . Since such a change in population results in a change in a cluster parameter, the cluster map 400 will be re-calculated. As mentioned previously, the change in the population typically results in a change in the cluster level centers in case the K-means cluster algorithm is applied. Therefore, the centers must be re-calculated. In case the cluster level centers are different the cluster levels will inherently change, e.g. in a way as shown in FIG. 5 . Accordingly, by moving the boundary parameter 405 in that way, the cluster centers are indirectly re-defined. [0042] FIG. 6 shows an embodiment of applying a clustering algorithm where the histogram bars in distribution of the domains 401 - 403 can partly overlap 601 . This means that a single histogram bar e.g. at the boundary between cluster level B 409 and C represent voxels from cluster level B and C, i.e. contains blue and red color. This results in that the boundaries between two adjacent distributions are not as abrupt as shown in FIG. 4 . This can result in a better clustering when changing the boundary parameter 405 . As shown in FIG. 5 the result of changing the boundary parameters in FIG. 4 could result in a very good clustering where a single cluster level C 408 is formed. [0043] FIG. 7 shows an embodiment of a device 700 according to the present invention for interactively evaluating and rearranging a cluster map of voxels in an image, wherein the device 700 comprises a monitor 704 , an input means (I_M) 702 , a processor (P) 703 and in an embodiment a memory 706 . The monitor 704 is adapted to display the cluster map and the distribution of the voxels in the cluster map simultaneously to a user 701 . The input means (I_M) 702 is adapted to receive an input from the user indicting an updated boundary parameter. The input means can according comprise a keyboard, a mouse, a speech recognition system, or the like, that enables the user 701 to change the boundaries between the distribution domains (see 404 and 405 in FIG. 4 ). The received input is then converted into a boundary parameter. As an example, the boundary parameters 404 , 405 shown in FIG. 4 could show 35% and 65%, respectively (i.e. <35% belong to cluster level A, <65% belong to cluster level B and >65% to the cluster level C). The user could accordingly change it via a keyboard command to 45% and 60%, or only change one of the boundary parameters. The memory 706 stores the cluster algorithm applied, wherein based on the received boundary parameter 705 the processor (P) 703 notifies the clustering algorithm of the updated boundary parameter 705 . The result is that the clustering algorithm is at least partly re-run based on the updated parameter. [0044] In case the boundary parameter(s) are determined automatically, the processor (P) 703 is further adapted to evaluate the quality of the cluster map by e.g. calculate the variance within each respective cluster level and based thereon determine whether a new boundary parameter(s) should be defined. [0045] Certain specific details of the disclosed embodiment are set forth for purposes of explanation rather than limitation, so as to provide a clear and thorough understanding of the present invention. However, it should be understood by those skilled in this art, that the present invention might be practiced in other embodiments that do not conform exactly to the details set forth herein, without departing significantly from the spirit and scope of this disclosure. Further, in this context, and for the purposes of brevity and clarity, detailed descriptions of well-known apparatuses, circuits and methodologies have been omitted so as to avoid unnecessary detail and possible confusion. [0046] Reference signs are included in the claims, however the inclusion of the reference signs is only for clarity reasons and should not be construed as limiting the scope of the claims.	This invention relates to rearranging a cluster map of voxels in an image aiming at the reduction of sub-cluster scatter. The cluster map that includes two or more cluster levels is displayed to the user along with the distribution of the voxels within each respective cluster levels. The aim is to enable the user to evaluate the quality of the cluster map and based on the evaluation to change the distribution of the voxels. Such a change in the distribution will result in an update of the cluster map.	6
BACKGROUND OF THE INVENTION This invention relates to a method for pressurizing containers by means of dispensing liquefied nitrogen into metal cans made of relatively thin aluminum or steel material, sealing the cans and then causing the liquefied nitrogen to gassify in the cans so as to preserve the contents of the cans and to create pressure therein to impart to them sufficient strength. The invention is suitable for preparing cans filled with liquid beverages or drinks not containing carbon dioxide. A drawing and ironing method is now being widely used to manufacture what are referred to as two-piece cans made of steel or aluminum sheets having a wall thickness of about 0.15 mm. These two-piece cans as they are called are used for containing beverages because they are strong, efficient, lightweight and can be quickly heated or cooled. Aluminum cans also have the advantage that most liquids contained therein will not deteriorate or degrade in taste even though the inner surface of the cans is not subjected to any special treatment. In addition, since aluminum has an excellent workability, it is possible to integrally form its body or cylindrical portion and bottom portion, thereby reducing the manufacturing cost. When the thin walled aluminum or steel cans are charged with such liquid beverages as beer or beverage containing carbon dioxide, the carbon dioxide liberated creates an internal pressure sufficient to increase the mechanical strength of the cans. However, when the cans are filled with liquid beverages not containing carbon dioxide, for example, coffee, fruit juice, plain water and wine, the internal pressure is not created. Accordingly, for use in such liquid beverages not containing carbon dioxide, one alternative has been to increase the wall thickness for the purpose of increasing the mechanical strength of the cans, and thin sheets manufactured by the drawing and ironing method cannot be used. The general concept of adding liquid nitrogen to thin-walled containers has been broadly disclosed in U.K. Pat. No. 1,455,652; however, in that instance, the details of the apparatus are very sketchy. German OLS No. 3,141,465 published July 15, 1982, includes additional apparatus; however, this is concerned with specific details unrelated to the method herein. Japanese published applications Nos. 56-4521, 49-4389 and 145686/76, U.S. Pat. No. 2,978,336 and Canadian Pat. No. 1,062,671 also disclose use of liquid nitrogen in packaging but are not considered relevant to the present invention. SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a method for injecting into and sealing liquefied nitrogen in containers having a thin wall thickness, for example less than 0.2 mm, and partially filled with various types of liquid beverages or plain water so as to create an internal pressure which increases the mechanical strength of the thin-walled containers. According to one aspect of the invention there is provided a method for sealing nitrogen in a metal can wherein a liquefied nitrogen is injected into a metal can by means of a gun, the operation of the gun being controlled by a sensor detecting the metal can at a predetermined position and by an injection time regulator, and wherein the pressure of the liquefied nitrogen supplied to the gun is made constant, whereby the liquefied nitrogen is sealed off in the metal can while partially remaining in a liquid state. The method is additionally characterized in that the liquefied nitrogen is prepared in a container with a top portion thereof being filled with a gassified nitrogen, a pressure detector is connected to the top portion of said container for detecting the pressure of the gassified nitrogen contained therein, a signal produced by said pressure detector is supplied to a pressure control mechanism which makes constant the pressure of the liquefied nitrogen contained in said container by means of shut-off arrangements connected thereto, the liquefied nitrogen of a constant pressure is supplied to said gun through a conduit, and the operation of said gun is controlled by a sensor detecting said metal can being in a predetermined position and by an injection time regulator, whereby the liquefied nitrogen is sealed off in said metal can while partially remaining in a liquid state. A further feature of the method is that the liquefied nitrogen is supplied from a liquefied nitrogen cylinder to said gun through an intermediate tank, the operation of said gun is controlled by a sensor detecting said container being in a predetermined position and by an injection time regulator, a pressure of the liquefied nitrogen supplied to said gun is made constant, and the surplus liquefied nitrogen is returned back to said intermediate tank from said gun. The conduit supplying the liquefied nitrogen of a constant pressure to said gun is provided with a gas/liquid separator so that only the liquefied nitrogen is supplied to said gun. According to another aspect of the invention, the liquid beverage not containing carbon dioxide contained in the metal cans is preheated to a temperature of 60°-95° C. for sterilization. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings; FIG. 1 is a diagrammatic representation of apparatus utilized to carry out the invention; and FIG. 2 is a diagrammatic representation showing a modification of the apparatus shown in FIG. 1. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIG. 1, a nitrogen gas cylinder 1 and a liquefied nitrogen cylinder 2 are provided. The nitrogen gas cylinder 1 is communicated with the liquefied nitrogen cylinder 2 through a conduit 22 including a pressure regulator 3 and a motor operated valve 4. At the top portion 2a of the cylinder 2 containing nitrogen gas are provided a motor operated gas release valve 5 and a pressure detector 6. A pressure level signal produced by the pressure detector 6 is supplied to a pressure control unit 7, which may take the form of a computer or a back pressure regulator, and the output signal of the pressure control unit 7 is applied to the motor operated valves 4 and 5 to actuate them to either respectively increase or decrease pressure so as to maintain the pressure of the liquefied nitrogen in cylinder 2 at a substantially constant pressure. A conduit 17 extending into the body 2b of the cylinder 2 is in communication with a motor operated gun or injector 8 through a gas/liquid separator 11. The gun 8 injects liquified nitrogen into a metal can 20 successively brought to a position beneath the gun 8. Adjacent the can 20 is disposed a can sensor 10, and the output signal thereof is supplied to the motor operated gun 8 through a timer 9 for ejecting the liquefied nitrogen into the can 20 for a predetermined interval of time. The method of controlling the feed speed of cans and the method of sealing cans are well known in the art. Usually, the cans are continuously fed at a speed of from 600 to 1800 cans per minute and on average, at a speed of 1200 cans per minute. After injection of the liquified nitrogen the opening at the top of the can is immediately sealed off. In the modification shown in FIG. 2, the nitrogen gas cylinder 1 is omitted and an intermediate liquefied nitrogen tank 12 is connected to the liquefied nitrogen cylinder 2 via a motor operated valve 15 which is controlled by a liquid level controller 16 to maintain the level of the liquefied nitrogen in the intermediate tank 12 at a constant level. The liquefied nitrogen in the intermediate tank 12 is sent to the motor operated gun 8 via a pump 13 and a pressure regulator 14. Nitrogen gas generated while the liquefied nitrogen is conveyed to the gun 8 and surplus liquefied nitrogen are returned to the intermediate tank 12 via conduit 18. A pressurized air operated gun may be substituted for the motor operated gun. However, since liquefied nitrogen should be maintained at an extremely low temperature a motor operated gun is preferred in view of temperature difference and response speed. Following examples are given for explaining the embodiments of the method of this invention where apparatus shown in FIGS. 1 and 2 are used. EXAMPLE 1 This example uses the apparatus shown in FIG. 1. As is well known in the art, nitrogen is maintained in a liquid state when the temperature is below -196° C., and when the temperature rises above this temperature the liquefied nitrogen gassifies so that cylinders 1 and 2 and conduit 22 interconnecting them and the conduit 17 interconnecting the cylinder 2 and the gun 8 are coated with suitable heat insulating material. Under these conditions, liquefied nitrogen was injected into aluminum cans 20 each having a capacity of 267 cc and a wall thickness of 0.1 mm and manufactured by the drawn and iron method. Each can was filled beforehand with 256-258 cc of warm water preheated to 85° C. After injecting the liquefied nitrogen the opening at the top of the can is sealed off so that the liquefied nitrogen is filled in the can with a space therein of about 15-17 cc. The cans 20 were fed at a speed of 1200 cans per minute. The time of opening the gun 8 controlled by the can sensor 10 was set to 0.015 sec., and the gauge pressure at the top portion 2a in the cylinder 2 as 0.5 kg/cm 2 . Under these conditions, 0.2 cc of liquefied nitrogen was injected into each can 20 at a speed of 1200 cans/min. The opening into which the liquid nitrogen was injected was sealed off by applying a lid thereto in a time of about 1 second after injection of the liquefied nitrogen. Sealing was effected by double seaming the lid on. After sealing, the liquefied nitrogen gassified at a room temperature of 20° C. to increase the pressure in the sealed can to a gauge pressure of 0.8-1.2 kg/cm 2 which is sufficient to increase the mechanical strength of the can. EXAMPLE 2 In this example, the apparatus shown in FIG. 2 was used and the same aluminum can as used in Example 1 was used. The quantity of the liquefied nitrogen sent to the pump 13 was 5000 cc/min. The injection gun 8 had an inner diameter of 2.4 mm and the liquefied nitrogen was supplied at a pressure of 0.3 kg/cm 2 by the action of the pressure regulator 14. Surplus liquefied nitrogen was returned to the intermediate tank 12 via conduit 18. Each can 20 made of an aluminum sheet having a thickness of 0.1 mm had a capacity of 267 ml and was prefilled with 256 -258 ml of warm water preheated to about 85° C. Immediately thereafter, 0.25 cc of the liquefied nitrogen was injected into each can, and less than two seconds later a lid was applied to the can which sealed the same. After sealing, the internal pressure of the can was found to be at a gauge pressure of 0.8-1.2 kg/cm 2 at a temperature of 20° C. The results of Examples 1 and 2 show that the method of this invention are suitable for producing cans containing coffee, fruit juice, various drinks, etc. As above described, according to this invention, it is possible to manufacture strong cans filled with liquid beverages not containing carbon dioxide, and to inject liquefied nitrogen at high efficiencies. Although the teachings of the invention have been discussed with reference to certain specific disclosured embodiments, it is to be understood that these are by way of illustration only and that variations may be made in the methods and apparatus without departing from the spirit and scope of the invention, as defined by the appended claims.	Pressurization of containers with liquid nitrogen to impart container strength and content protection is effected by injecting a small quantity of liquid nitrogen before sealing the container by the methods and apparatus including a gas pressure system wherein liquid nitrogen is maintained by control means at a constant pressure with nitrogen gas being separated from liquid nitrogen before dispensing and a recirculating pump pressure system wherein liquid nitrogen from a second of two supplies is pumped through a conduit to a dispensing gun and surplus liquid and gas is returned to the supply.	1
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a miniature stacked microstrip antenna of wide band in radio communication apparatus. 2. Description of the Prior Art Conventionally, a standard microstrip antenna consists of a ground plane, a radiating element and a dielectric layer sandwiched between them. When a high-frequency voltage is supplied between the ground plane and the radiating element, the antenna has a resonance frequency decided by an effective wavelength (λ) in the dielectric layer. In this case, the radiating element is formed by a square having a side of λ/2. Furthermore, a microstrip antenna which short-circuits one whole edge of the radiating element with the ground plane in the standard microstrip antenna is known. The microstrip antenna can get the same resonance frequency as that of the standard microstrip antenna with an open area which is 1/2 or less. With the antennas as stated above, the resonance frequencies are determined by the dimensions of the radiating elements and the dimentions between the ground plane and the radiating elements. Therefore, the antennas have the disadvantage that it is difficult of being made still smaller in size as may be needed. Specially, the antennas become a large open area when they need a low resonance frequency. As another disadvantage, in a case where deviations have occurred between designed resonance frequency and the resonance frequency of the fabricated antenna, the dimension of the radiating element must be changed, and the correction of the resonance frequency is difficult. SUMMARY OF THE INVENTION An object of the present invention is to provide a stacked microstrip antenna having two resonance frequencies and being a miniature size. Another object of the present invention is to provide a stacked microstrip antenna capable of controlling resonance frequencies easy. To realize above objects, the stacked microstrip antenna of the present invention has a ground plane, a first dielectric layer formed on the ground plane, a first radiating element formed on the first dielectric layer, a second dielectric layer formed on the first radiating element, a second radiating element formed on the second dielectric layer, a short-circuiting conductor which short-circuits the first and second radiating elements with the ground plane, and a feeder for feeding power to one of the first and second radiating elements. The stacked microstrip antenna can attain double-channel duplex characteristics in utilizing a coupling between the first and second radiating elements. The short-circuiting conductor is equivalent to loading with an inductance, so that the short-circuiting conductor leads to lowering in the resonance frequencies. Therefore, the stacked microstrip antenna can achieve the miniaturization of the antenna. Further, the stacked microstrip antenna can control the resonance frequencies with changing the widthwise dimension of the short-circuiting conductor. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating an embodiment of the present invention; FIG. 2 is an exploded view of FIG. 1 to better illustrate the construction; FIG. 3 is a perspective view illustrating an alternate embodiment of the present invention; FIG. 4 is a perspective view illustrating an alternate embodiment of the present invention; FIG. 5 is a diagram illustrating the variation of a resonance frequency corresponding to changing the widthwise dimension of a short-circuiting conductor; FIG. 6 is a diagram illustrating return loss characteristics of a stacked microstrip antenna shown in FIG. 1; FIG. 7 is a diagram illustrating radiation pattern characteristics of a stacked microstrip antenna shown in FIG. 1; and FIG. 8 is a perspective view illustrating an alternate embodiment of the present inventions. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will now be described with reference to the accompanying drawings representing and embodiment thereof. FIG. 1 is a perspective view illustrating an embodiment of the present invention, and FIG. 2 is an exploded view of FIG. 1 to better illustrate the construction thereof. A first radiating element 3 is mounted on a ground plane 6 through a first dielectric layer 1. And a second radiating element 4 is mounted on the first radiating element 3 through a second dielectric layer 2. They are brought into completely close contact or are placed in close proximity. By way of example, as a method for obtaining the close contact, one can use pressed bonding with a binder on an insulator, or clamping with a screw which penetrates the first and second dielectric layers 1, 2 somewhat spaced from the edges of the first and second radiating elements 3, 4 and that do not contribute to antenna characteristics, while as a method for obtaining a close proximity, the use of air layer spacers of low permittivity can be considered. The first radiating element 3 is short-circuited to the ground plane 6 through a copper plate (or copper foil) 5b by soldering. And the second radiating element 4 is short-circuited to the first radiating element 3 through a copper plate (or copper foil) 5a by soldering. Further, a feeding unit having a coaxial line 7 and a connector pin 8 are mounted. In this case, the first radiating element 3 is provided with a hole 3a so that the connector pin 8 may become out of electrical contact. In this stacked microstrip antenna, since power is fed to a feeding point F by the feeding unit, a coupling arises between the first and second radiating elements 3, 4. So that double-channel duplex is realized. By the way, a dimension from the end of the radiating element to the end of the dielectric layer can be reduced down to a dimension which is nearly equal to the combined thickness h of the first and second dielectric layer 1, 2. Besides, although the copper plates 5a, 5b are depicted as separate members in FIG. 2 they may well be formed as being unitary with corresponding the first and second radiating elements 3, 4 or the ground plane 6. As a practical example, the stacked microstrip antenna which has two resonance frequencies of 3.68 [GHz] and 4.61 [GHz] is obtained under the fabricating conditions of a 1 ×b 1 =7.2(mm)×14.4(mm), a 2 ×b 2 =6.5(mm)×13.0(mm), h=1.2(mm), l 1 =l 2 and l 1 /b 2 =0.3 with the first and second dielectric layers 1,2 of εr=2.55. FIG. 3 is a perspective view illustrating an alternate embodiment of the present invention. The stacked microstrip antenna shown in FIG. 3 is an example in which the widthwise dimension l 11 of the copper plate 5b is smaller, while the widthwise dimension l 21 of the copper plate 5a is larger. When the antenna is thus constructed, the resonance frequency f 2 of the second radiating element 4 becomes higher than the resonance frequency f 1 of the first radiating element 3. With such a construction, even when the dimensions of the first and second radiating elements 3, 4 are equal as a 1 =a 2 and b 1 =b 2 by way of example, the resonance frequencies f 1 , f 2 take unequal values, and the double-channel duplex of the antenna is realized. FIG. 4 is a perspective view illustrating an alternate embodiment of the present invention. The stacked microstrip antenna shown in FIG. 4 is an example in which the widthwise dimension l 12 of the copper plate 5b is larger, while the widthwise dimension l 22 of the copper plate 5a is smaller. When the antenna is thus constructed, the resonance frequency f 1 of the first radiating element 3 becomes higher than the resonance frequency f 2 of the second radiating element 4. With such a construction, even when the dimensions of the first and second radiating elements 3, 4 are equal as a 1 =a 2 and b 1 =b 2 by way of example, the resonance frequencies f 1 , f 2 take unequal values, and the double-channel duplex of the antenna is realized. In this manner, by changing the individual widthwise dimensions of the short-circuiting conductors, the resonance frequencies f 1 , f 2 can be controlled, and the double-channel duplex of the antenna is permitted. In addition, it is effective adjustment means for attaining desired resonance frequencies. FIG. 5 illustrates the variation of a resonance frequency in the case where the widthwise dimension of a short-circuiting conductor was changed in a stacked microstrip antenna shown in FIG. 1 which had the first and second dielectric layers 1, 2 of a relative dielectric constant εr=2.55 and the original frequency to corresponding to the whole edge short-circuiting and in which, letting h denote the combined thickness of the first and second dielectric layers 1, 2 and λo denote the wavelength in the free space, h/λo=approximately 0.01 held. It is understood from FIG. 5 that, letting S denote the widthwise dimension of the short-circuiting conductor and b denote the dimension of the edges of the first and second radiating elements 3,4 in tough with the short-circuiting conductors, the resonance frequency for s/b=0.3 becomes at least about 30% lower than the resonance frequency for s/b=1.0 corresponding to the whole edge short-circuiting. Usually, the size of the radiating element is proportional to the wavelength, and it enlarges more as the resonance frequency becomes lower. In view of the above result, however, the resonance frequency could be lowered in spite of the radiating element size of higher resonance frequency. That is, reduction in the size of the radiating element was achieved. FIG. 6 is a diagram illustrating return loss characteristics of the stacked microstrip antenna shown in FIG. 1. FIG. 6 was measured on condition that the widthwise dimensions l 1 , l 2 of the short-circuiting conductors were equalized, l 1 /b 2 =0.3 was held, and h/λo=at least 0.01 was held. A frequency interval f 1 -f 2 is substantially constant and the resonance frequencies shift into a lower frequency region, when the widthwise dimensions of the short-circuiting conductors are reduced. FIG. 7 is a diagram illustrating radiation pattern characteristics of the stacked microstrip antenna shown in FIG. 1. The radiation pattern characteristics shown in FIG. 7 indicate that the antenna can put to practical use. FIG. 8 is a perspective view illustrating an alternate embodiment of the present invention. A ground plane 60 and a first radiating element 30 are opposed with a predetermined space defined therebetween, a second radiating element 40 is further opposed over the first radiating element 30 with a predetermined space defined therebetween, and the ground plane 60 and the first and second radiating elements 30, 40 are short-circuited by a short-circuiting conductor 50. A coaxial line 70 is connected to the ground plane 60, and the second radiating element 40 is fed with power by a connector pin 80. On this occasion, the first radiating element 30 and the connector pin 80 are held in an electrically non-contacting state. Even the stacked microstrip antenna in which the dielectric layers are replaced with the air layers in this manner, achieves the effect of the present invention. The gain of the miniature microstrip antenna of the present invention is proportional to an open area likewise to that of the conventional microstrip antenna. Although the shape of each radiating element has been square in the present invention, it may well be another shape, for example, a circular or elliptical shape. As described above, according to a construction based on the present invention, an antenna of lower frequencies can be realized with dimensions equal to those of an antenna of higher frequencies. That is, the antenna becomes smaller in size, so it can be readily built in the casing of a radio communication apparatus.	The stacked microstrip antenna has a ground plane, a first dielectrical layer, a first radiating element, a second dielectric layer, a second radiating element and a short-circuiting conductor for short-circuiting between the first and second radiating elements and the ground plane. The stacked microstrip antenna attains double-channel duplex characteristics with utilizing the coupling between the first radiating element and the second radiating element, when a power is fed to the antenna. Further, the widthwise dimension of the short-circuiting conductor is controlled, whereby the antenna leads to the miniaturization of the radiating elements, namely, the miniaturization of an antenna proper, and it is permitted to be tuned to two desired frequencies with ease.	7
BACKGROUND OF THE INVENTION [0001] 1. Technical Field [0002] This invention relates to a device to enable an adult to efficiently attend to an infant by providing a folding, rotatable, adjustable surface on which to place an infant to change the diaper of said infant in an automobile. [0003] 2. Description of Prior Art [0004] A search of prior art revealed: [0005] U.S. Pat. No. 4,876,970 sets forth a coin operated, wall mounted fold down child diaper changing table that is placed in public lavatories for parents with an infant, who are just out and about, or traveling. [0006] U.S. Pat. No. 2,735,737 describes a diapering support comprising a wall mounted housing supporting a roll of disposable paper to be drawn downward from the housing. The housing itself contains a multi-hinged flat surface secured at one end and two folding arms on the other. [0007] U.S. Pat. No. 2,817,571 sets forth a wall mounted folding table secured by means of a plurality of articulating arms and springs provided for locking said table in the down or extended position during non-use to be folded back against the support wall. [0008] U.S. Pat. No. 4,613,996 sets forth a folding child support secured to a wall surface in a rectangular enclosure. The enclosure contains a plurality of compartments and shelves as well as utility features mounted therein. The enclosure includes a hingeably secured pivotable outer surface in the closed position and an extended position forming a child care surface. [0009] Other practitioners have provided examples of folding table mechanisms included in: U.S. Pat. Nos. 2,815,700, 2,857,222, 3,232,663 and 3,689,344. [0010] The foregoing examples provided various mechanisms for wall mounted infant care fold down tables and some during traveling, but none provided an in car folding, adjustable table, should the traveler not be near a public facility when needed. SUMMARY OF THE INVENTION [0011] The object of this invention is to present an on board, in car, folding adjustable infant care station for the traveler to be utilized whether or not a public facility is available by merely pulling off the road and attending to the needs of the child without leaving the automobile. DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 depicts a right oblique view of the Portable Infant Auto Changing Table affixed to the rear surface of an automobile front seat in the folded, or travel position. [0013] FIG. 2 shows a left side view of the front seat of an automobile with the Portable Infant Auto Changing Table components in the folded, or traveling position. [0014] FIG. 3 illustrates another side view of the table of the invention in the folded position to accept an infant for care. [0015] FIG. 4 shows a front view of the invention, while FIG. 5 reveals a side view of the component parts comprising all the adjustment mechanisms. All adjustment mechanisms are typical. DESCRIPTION OF THE PREFERRED EMBODIMENT [0016] FIG. 1 sets forth a right oblique view of the front seat of an automobile affixed with the Portable Infant Auto Changing Table in the folded, or travel mode. The automobile seat 11 supports the head rest 12 with the Portable Infant Auto Changing Table frame 13 resting on the top of the back support 11 and forward of the head rest 12 . The frame 13 , extends vertically downward on each side of the seat back support 11 , to the bottom of said seat back support and horizontally rearward to the vertical adjustment mechanism 14 . The vertical adjustment mechanism 14 is adjustably affixed to the vertical support bar 15 and extends upward from the horizontal frame 13 to the center of the changing table 16 . The changing table 16 is folded vertically against the rear surface of the back support portion of the seat 11 , by activating both the table vertical adjustment mechanisms 14 and 17 , located at each end of the vertical support bar 15 . The utility trays 19 are affixed to the two descending portions of the frame 13 . The Portable Infant Auto Changing Table can be affixed to the head rest 22 by simply holding said table components in the horizontal position above the head rest, lowering the frame 23 in front of the head rest 22 until coming to rest on the top portion of the seat support 21 and rotating the Portable Infant Changing Table downward until it comes to rest on the rear surface of the seat back support 21 . To remove the Portable Infant Auto Changing Table, simply reverse the procedure. [0017] FIG. 2 shows a left view of the front seat 21 , of an automobile and the head rest 22 , with the frame 23 resting around the front bottom portion of the head rest 22 , affixing it to the seat back support 21 . The utility tray 24 is affixed to the descending portions of the frame 23 . The table 25 is folded and resting on the rear surface of the back support portion of the seat 21 . The vertical support bar 28 has two adjustment mechanisms 27 and 29 , located at each end. The horizontal rotation control mechanism 26 allows the operator to adjust the table to the desired position when folding the table 25 for travel, or not in use. [0018] FIG. 3 depicts also the left view of the front seat of an automobile 31 , head rest 32 , supporting frame 33 and utility tray 34 with the Portable Infant Auto Changing Table 35 -A in the horizontal position to receive an infant placed on the foam pad 35 -B, rotated horizontally for convenience by activating the horizontal rotation mechanism 36 . The desired position is attained by pulling the knob 36 downward far enough to clear the table for rotation and moving the table 35 -A to that position. The table 35 -A is supported by the vertical support bar 38 , with vertical adjustment mechanisms 37 and 38 located at each end. [0019] FIG. 4 shows a front view of the adjustment mechanisms. The fixed disc 41 is affixed to the frame portion 42 and contains a plurality of holes 46 , strategically placed to accept the rotationally adjustable peg 45 attached to the pull knob 44 affixed to the spring bar 43 which is further attached to the rotational bar 42 . [0020] FIG. 5 describes a side view of the adjustment mechanism. 51 is the stationary disc containing a plurality of strategically spaced holes 56 , so when the adjustment knob 54 is pulled, the adjustment peg 55 is dislodged from the adjustment hole 56 and can be rotated to the desired position. By releasing the knob 54 , the locking peg 55 is forced into an adjustment hole 56 by the spring action of the spring bar 53 , that is rotationally attached to the rotational bar 52 .	A removable, adjustable, portable apparatus positioned on the rear surface of a front seat of an automobile, secured around the seat head rest, providing a surface when positioned to aupport an infant to change a diaper in an automobile.	1
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion adaptive frequency folding method and circuit suitable to a system having a restricted frequency band, such as a television, video tape recorder, laser disc player or the like for folding a signal component having a predetermined frequency over a signal component below the frequency. 2. Description of the Prior Art In general, it is well-known that a conventional VHS video tape recorder is incapable of recording a signal having a high frequency above 2.5 MHz from the view point due to the limited characteristics of the magnetic video tape which contributes to a deterioration of a picture image upon reproduction by the video tape recorder because only 60% of a television signal band is utilized in the system. Meanwhile, a super-VHS video tape recorder can send a signal beyond a television signal band so as to provide an excellent picture image, but it is not compatible with the existing VHS video tape recorder. That is, when a signal recorded by a standard VHS video tape recorder is reproduced by means of the super-VHS video tape recorder system, the resolution of the reproduced signal is deteriorated considerably. Further, the super-VHS video tape recorder requires a magnetic tape of a high standard as well as a recording/replaying apparatus of superior quality. To address this deficiency, a video signal recording/replaying apparatus which can record a video signal having a bandwidth wider than that of a video signal to be recorded by the standard VHS video cassette recorder onto the standard magnetic tape and is compatible with the standard-VHS video cassette recorder has been proposed in, for example, U.S. Pat. No. 5,113,202. With the patent, a motion signal indicating a movement of the video image to be reproduced is appropriately extracted and then the extracted motion signal is modified and recorded into a color signal. The motion signal is used to control a transmission of a full band-width signal arears to be unfolded in an original frequency band during reproduction by the system, wherein a high frequency component of a brightness signal is folded over a low frequency component thereof. According to the construction, however, when the motion signal is not correctly detected upon reproduction of a picture image, the picture image is deteriorated in quality because of artifacts such as dot crawl patterns or the likes occurred owing to frequency interleaving between the to motion signal and a folding carrier. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a motion adaptive frequency folding method and circuit for differently folding a signal having a restricted frequency band by using a motion signal indicating a motion video image and recording the signal of full bandwidth so as to prevent deterioration of the quality of the video image due to artifacts upon reproduction the motion. That is, the object of the present invention is to provide a method of folding the signal component above a predetermined frequency over the signal component below the frequency in order to record a video signal of full bandwidth on the recording medium having a restricted bandwidth. To achieve the above object, a motion adaptive frequency folding method comprising the steps of: separately filtering high frequency and low frequency brightness signals, each having a bandwidth above and below the bandwidth of a recording medium, from a brightness signal with a full bandwidth; detecting a motion signal from the brightness signal with a full bandwidth; controlling gain of the high-frequency brightness signal; limiting an output level of the high-frequency brightness signal controlled in the the motion signal; detecting step and folding the high-frequency brightness signal at the time of detection of a still image over the low-frequency brightness signal. Also, the present invention provides a motion adaptive frequency folding circuit comprising: a first horizontal low pass filter means for filtering a low-frequency brightness signal having a bandwidth below a recording medium bandwidth from a brightness signal having a full bandwidth; horizontal high pass filter means for separating a high-frequency brightness signal having a bandwidth above the recording medium bandwidth from the brightness signal; a motion signal detector means for producing a factor corresponding to a motion signal from the brightness signal; a gain controller means for controlling gain of the high-frequency signal output from the horizontal high pass filter; a signal limiter for limiting of the high-frequency brightness signal output from the gain controller in dependence upon the motion signal factor produced by the motion signal detector; an adder for adding the high-frequency brightness signal limited by the signal limiter and the low-frequency brightness signal output from the first horizontal filter; a subsampling device for folding the high-frequency brightness signal above a bandwidth of a transfer medium of the brightness signal outputted from the adder over the low-frequency brightness signal of the brightness signal; and, a second horizontal low pass filter for passing only the signal component below the bandwidth of the recording medium in the folded brightness signal. The above and other objects, features and advantages will be apparent from the following description taken with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a motion adaptive frequency folding circuit according to a preferred embodiment of the present invention; FIG. 2 is a detailed block diagram of a motion signal detector in FIG. 1; FIG. 3 is a graph showing gain of an adaptive emphasis/de-emphasis in FIG. 1; and, FIG. 4 is a view showing a field offset subsample pattern of the motion adaptive frequency folding circuit in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Thereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 1, there is shown a block diagram of a motion adaptive frequency folding circuit according to the preferred embodiment of the present invention. In the drawing, a first horizontal low pass filter 10 receives a brightness signal Y and passes a signal component below a predetermined cutoff frequency, for example, 2.5 to 3 MHz. A horizontal high pass filter 20 also receives the brightness signal Y and passes a signal component above the cutoff frequency. A motion signal detector 30, detects a motion signal from the brightness signal Y and produces a motion factor K corresponding to the motion signal. Further, an adaptive emphasis/de-emphasis portion 40 which is referred as a gain controller, serves to increase or decrease of the signal level from the horizontal high pass filter 20. A signal limiting portion 50 limits the signal supplied from the adaptive emphasis/de-emphasis portion 40 on the basis of the motion factor K produced by the motion signal detector 30. An adder 60 adds the low-frequency brightness component signal outputted from the horizontal low pass filter 10 and the high-frequency brightness component signal from the signal limiting portion 50. The added signal is input to a subsampling portion 70 which executes a field offset subsampling so as to fold the signal component above a predetermined reference frequency band over the signal component below the reference frequency band of the adder signal. In the drawing, 80 denotes a second horizontal low pass filter which extracts the signal below the reference frequency in the folded signal from the subsampling portion 70. FIG. 2 shows a detailed block diagram of the motion signal detector in FIG. 1. As shown in FIG. 2, the motion signal detector 30 comprises a temporal high pass filter 31 for detecting the motion signal from the brightness signal, a rectifier/absolute value producer portion 32 for rectifying the motion signal from the temporal high pass filter 31 and obtaining an absolute value of the rectified signal, a signal spreader 33 for spreading the absolute-valued motion signal in horizontal, vertical and time, and softening an abrupt change of the motion signal, and a motion signal factor producer 34 for producing a motion factor K corresponding to the motion signal output from the signal spreader 33. Now, the construction of the present invention will be described in detail with reference to FIGS. 3 and 4, in which FIG. 3 shows a gain characteristic view of the adaptive emphasis/de-emphasis and FIG. 4 shows a field offset subsample. In accordance with the conventional VHS video tape recorder as previously described, a signal having a high frequency above 2.5 to 5.0 MHz or 3.0 to 5.0 MHz cannot be recorded on the recording medium on the view point of the property of the medium. For this reason, a cut-off frequency is preferably set to be 2.5 to 3.0 MHz. When the cut-off frequency is set to be 2.5 MHz, the first horizontal low pass filter 10 extracts the brightness component having a frequency below 2.5 MHz, while the horizontal high pass filter 20 extracts the brightness signal component having a frequency above 2.5 MHz. Further, the motion signal detector 30 detects the motion signal from the brightness signal Y so as to produce the motion factor K corresponding to the motion signal. Consequently, in the motion signal detector 30 shown in FIG. 2, the temporal high pass filter 31 detects the motion signal of the brightness signal Y and the rectifier/absolute value producer portion 32 rectifies the motion signal applied from the temporal high pass filter 31 and produces the absolute value of the rectified motion signal. The motion signal thus substituted by the absolute value is spreaded by means of the signal spreader 33 in horizontal, vertical and time. Upon spreading the motion signal, artifacts such as blurring to be occurred in switching an abruptly changed portion of the motion signal by the signal limiting portion 50 shown in FIG. 1 can be effectively prevented. More particularly, the picture may be deteriorated at an edge due to the transition from a still video image to a motion video image. In this connection, the spreading is executed to extend the range of the motion signal so as to gradually change the motion signal. Next, the motion signal factor producer 34 produces the motion signal factor K on the basis of the output value of the signal spreader 33 and inputs the motion factor K to the signal limiting portion 50 shown in FIG. 1 so that the high-frequency signal component to be folded is limited effectively. Meanwhile, the brightness signal with a frequency above 2.5 MHz passed through the horizontal high pass filter 20 is provided to the adaptive emphasis/de-emphasis portion 40 having a gain characteristic as shown in FIG. 3. Accordingly, the brightness signal is limited in level by the adaptive emphasis/de-emphasis portion 40. For example, assuming that the gain characteristic of the emphasis/de-emphasis portion 40 is set to be 6*A (where, A is an absolute value of the horizontal high pass filter 20, when the output value of the horizontal high pass filter 20 is set to be 4, the output value of the adaptive emphasis/de-emphasis portion 40 becomes √4. As a result, the adaptive emphasis/de-emphasis portion 40 produces the output value larger than that of the horizontal high pass filter 20. Alternatively, when the output value of the horizontal high pass filter 20 is set to be -9 or +9, the output level of the adaptive emphasis/de-emphasis portion 40 becomes √-54 or °+54 lower than the input value of the horizontal high pass filter 20. Accordingly, as the output value of the horizontal high pass filter 20 is increased, the output value of the adaptive emphasis/de-emphasis portion 40 is decreased to 1/4 from the original value depending upon the gain characteristic shown in FIG. 3. Hence, it should be noticed that when the output value of the adaptive emphasis/de-emphasis portion 40 is decreased to 1/4, even if the folded component is unpleasantly displayed on a screen when the signal recorded on the magnetic video tape by means of the video tape recorder employed with the present invention is replayed by the existing video tape recorder, a magnitude of the high frequency signal component is controlled to thereby prevent a folding of the signal. As a result, it improves the compatibility between the recorders. Moreover, when the gain characteristic of the adaptive emphasis/de-emphasis portion 40 is set to be 1 or more, if a minute signal in level is recorded onto or reproduced from the recording medium such as the video tape, it is possible to prevent the signal from being deteriorated and to improve a signal resolution even if noise is induced thereto upon reproduction of the signal. The output signal of the adaptive emphasis/de-emphasis portion 40 thus controlled in gain is transferred to the signal limiting portion 50 which limits the output signal on the basis of the motion factor K output from the motion signal detector 30. More particularly, when the brightness signal Y is detected as a signal of a still picture image, the motion factor K of the motion signal detector 30 is set to be "zero". In this case, the signal limiting portion 50 passes the output value of the adaptive emphasis/de-emphasis portion 40 toward the adder 60. Alternatively, when the input composite video signal is detected as a signal of a semi-motion picture image, the motion factor K of the motion detector 30 is set to be 0.125, for example. Therefore, the output, 1-K of the signal limiting portion 50 is set to 0.875 in rate so that the 0.875 in rate of the output value of the adaptive emphasis/de-emphasis 40 is folded by passing through the signal limiting portion 50. When the brightness signal Y indicates the motion picture image, the motion factor K of the motion signal detector 30 becomes 1 and, hence, the signal limiting portion 50 cuts off the output value of the adaptive emphasis/de-emphasis 40. In other words, when the motion factor K from the motion signal detector 30 is set under a predeterminded reference level, the signal limiting portion 50 outputs the high-frequency brightness signal controlled in gain by the adaptive emphasis/de-emphasis portion 40. That is, when a magnitude of the motion factor K is under a predetermined level which indicates a still picture image signal, the signal limiting portion 50 outputs the gain-controlled high frequency brightness component. Further, the reference level can be arbitrarly set to determine the still picture image. Accordingly, when the still picture image is determined, the adder 60 adds the high-frequency component passed through the signal limiting portion 50 and the low-frequency component passed through the first horizontal low pass filter 10. Alternatively, when the motion picture is determined, the adder 60 outputs only the low-frequency component passed through the first horizontal low pass filter 10. Further, when the semi-motion picture is determined, the adder 60 adds the high-passed signal component according to the presently set value of the motion factor K and the output signal of the first horizontal low pass filter 10. Consequently, the subsampling portion 70 performs a field offset subsampling with respect to output signal of the adder 60 to fold the high-frequency signal component over the low-frequency component. The folded signal is then entered to the second horizontal low pass filter 80 which cuts off the signal having a frequency above 2.5 MHz. Thereafter, the output signal of the second horizontal low pass filter 80 is supplied to an output terminal OUT through which the signal is recorded on a predetermined recording medium. As described above, even if the folded signal component above 2.5 MHz in frequency, it has no effect on the video image to be reproduced. Furthermore, under consideration of the compatibility with the existing VHS video tape recorder, limitation of the signal band is carried out to prevent the deterioration of the picture due to the folded signal contained in the component above 2.5 MHz. Additionally, a detailed description will be made with relation to the frequency filding performed by the subsampling portion 70. Firstly, the composite video signal having a bandwidth of 5.0 MHz is sampled with sampling rate of 10 MHz satisfying a Nyquist theory by an analog to digital (A/D) converter (not shown). The sampled composite video signal is passed through a brightness/color signal separating circuit (not shown) and the low-frequency component of the video signal is passed through the first low pass filter 10 while high-frequency component is passed through the horizontal high pass filter 20, adaptive emphasis/de-emphasis portion 40 and signal limiting portion 50. The low and high frequency components are added by the added 60 and then entered to the subsampling portion 70. Accordingly, the subsampling portion 70 subsamples the video signal having a frequency of 5.0 MHz to fold the high frequency component above 2.5 MHz over the low frequency component under 2.5 MHz on the basis of a reference frequency of 2.5 MHz. In the sampling method performed by the subsampling portion 70, the signal sampled with the sampling frequency of 10 MHz is further sampled on alternative samples in a horizontal direction. More particularly, the samples on the first line are alternatively sampled and the sampling between the lines is executed in a manner opposed to the upper line, as shown in FIG. 4. In addition, each of the first to fourth fields, for example, is sampled in a manner shown in FIG. 4 so that the high frequency is folded over the low frequency band as described above, and a spectrum of the folded signal is positioned in the vicinity of a Funkinuki hole. The folded signal from the subsampling portion 70 is entered to the horizontal low pass filter 80 which cuts off the signal above 2.5 MHz, and then output outwardly. As described above, according to the motion adaptive frequency folding method and circuit, the high-frequency component of the brightness signal is increased or decreased on the basis of the gain to be controlled according to the magnitude thereof and is folded depending upon an amount of the motion signal so that the brightness signal is recorded in full band on the recording medium having a restricted bandwidth, whereby the video signal is successfully reproduced in good quality.	A motion adaptive frequency folding method and circuits thereof for folding high-frequency components over low-frequency components of a brightness signal for enabling recording of a video signal having a full bandwidth onto a recording medium having a restricted bandwidth in order to improve resolution of a video image by preventing deterioration of the video image due to artifacts and noise. The motion adaptive frequency folding method comprises the steps of detecting high-frequency components above a reference frequency band and low-frequency components below the reference frequency band of the brightness signal, detecting a motion coefficient indicative of motion of an image from the brightness signal, controlling a magnitude of the high-frequency components and limiting transmission of the high-frequency components of the brightness signal in dependence upon said motion coefficient, and folding the high-frequency components above said reference frequency band having relative magnitudes controlled and limited by said motion coefficient over the low-frequency components below the reference frequency band of the brightness signal to produce a folded brightness signal.	7
FIELD OF INVENTION The invention concerns anchoring means for intervertebral implants, as well as an intervertebral implant with two anchoring parts and a method to fasten an intervertebral implant on adjacent bodies of the vertebra. BACKGROUND OF THE INVENTION Intervertebral implants, that may be constructed, for example, as intervertebral disc prosthesis and are introduced into the intervertebral space between two adjacent intervertebral discs after the removal of a damaged, natural intervertebral disc or of a damaged nucleus of an intervertebral disc, have to be fixed on the end surfaces of the adjacent bodies of the vertebra, so that the implant could not move with the passage of time. In the fixing of the implant on the end plates of the bodies of the vertebra one differentiates between primary and secondary stabilization. The primary stabilization is necessary immediately following the operation and is preferably carried out by introducing anchoring means, fitted to the implant, into the end plates on the adjacent bodies of the vertebra. The secondary stabilization is achieved by the bone growing on the implant, but one has to reckon with a period of approx. 6 weeks until an adequate fixing of the implant. From U.S. Pat. No. 5,683,465 Shinn an intervertebral disc prosthesis is known, that in one embodiment is fixed on the end plates of the adjacent bodies of the vertebra by means of pins that can pass through the cover plates fitted to the exterior of the implant. It is a disadvantage of this fixing when using these pins, that the pins have to be fastened on the end plates either prior to the introduction of the intervertebral disc prosthesis into the intervertebral space, what during the introduction of the implant into the intervertebral space demands an increased traction of both bodies of the vertebra, or that after the introduction of the implant into the intervertebral space the pins have to be individually pressed into the end plates of the adjacent bodies of the vertebra, resulting in a prolonged operating time. From U.S. Pat. No. 5,683,465 Shinn an intervertebral disc prosthesis is known, that in one embodiment is fixed on the end plates of the adjacent bodies of the vertebra by means of pins that can pass through the cover plates fitted to the exterior of the implant. It is a disadvantage of this fixing when using these pins, that the pins have to be fastened on the end plates either prior to the introduction of the intervertebral disc prosthesis into the intervertebral space, what during the introduction of the implant into the intervertebral space demands an increased traction of both bodies of the vertebra, or that after the introduction of the implant into the intervertebral space the pins have to be individually pressed into the end plates of the adjacent bodies of the vertebra, resulting in a prolonged operating time. SUMMARY OF THE INVENTION This is where the invention wants to provide remedy. The object of the invention is to produce anchoring means for intervertebral implants, that can be brought into a first position for the purpose of introducing the implant in the scraped out intervertebral space, where they do not project with their end past the cover plates and after the introduction of the implant can be brought in a simple manner into a second, lockable position, where the anchoring means are pressed into the end plates of the adjacent bodies of the vertebra and serve the purpose of primary stabilization of the implant. The invention achieves this objective with anchoring means for intervertebral implants having an anchoring part comprising a central axis and two end faces transverse to the central axis, each anchoring means comprises at least two spikes that protrude past the end faces, are parallel to the central axis and can be pressed into an end plate of a body of the vertebra, characterized in that the anchoring part comprises a hollow space passing through parallel to the central axis, the anchoring part comprises fastening means by means of which the anchoring part can be detachably locked on an intervertebral implant, the intervertebral implant comprises a closing plate each that intersects the central axis, and the closing plates can pass through the hollow spaces in the anchoring parts, as well as a method to fix an intervertebral implant comprising the steps a) enabling the access to the intervertebral space by means of an antero-lateral, ventral lateral, transperitonial or retroperitonial surgical procedure, b) tractioning both bodies of the vertebra adjacent to the intervertebral space, c) scraping out the intervertebral space, d) introducing the intervertebral implant with the anchoring means pushed together, e) moving the anchoring parts axially away from one another until the spikes are adequately pressed into the base plate or the cover plate of the adjacent bodies of the vertebra, and f) fixing the fastening means on the intervertebral implant. The anchoring means according to the invention serve the purpose of fixing an intervertebral implant on the end plates of bodies of the vertebra and basically comprise an anchoring part with a central axis, a hollow space passing through the anchoring part in the direction of the central axis and two end faces provided transverse to the central axis, at least two spikes that protrude past the end faces and can be pressed into the end plate of a body of the vertebra, and fastening means, by means of which the anchoring means, together with the spikes, can be detachably locked on an intervertebral implant. The basic advantages, achieved by the invention, are that with the anchoring means according to the invention only a minimal traction of two adjacent bodies of the vertebra is necessary when implanting an intervertebral implant into the intervertebral space, and by means of the anchoring means according to the invention an intervertebral implant can be simply fixed on the bodies of the vertebra adjacent to the intervertebral implant. The fastening means can be, for example, snapped in on an intervertebral implant transversely to the central axis of the anchoring means and be elastically deformed, can be pressed or screwed into the anchoring part transversely to the central axis, or executed by a taper joint between the wall of the hollow space and the intervertebral implant. In a preferred form the fastening means can be elastically deformed transversely to the central axis of the anchoring means and in the non-deformed state protrude into the hollow space in the anchoring part. Elastically deformable fastening means have the advantage, that the anchoring part can be produced in one piece and the danger of losing a component can be avoided. These fastening means are preferably constructed as hooks with lugs directed towards the central axis. In another embodiment the fastening means are provided in the hollow space of the anchoring part. This will bring with it the advantage that the anchoring part can be produced without parts axially protruding past the end faces and, for example, the pressing of the spikes into the base plate or cover plate of an adjacent body of the vertebra by means of a suitable surgical instrument will not be hindered by projecting parts. In yet another embodiment the hooks are so let into the recesses in the wall of the hollow space that is parallel to the central axis, that in the case of the hooks not being deformed transversely to the central axis the lugs of the hooks protrude into the hollow space and in the case of the hooks being deformed transversely to the central axis the hooks, together with their lugs facing the central axis, can be accommodated in the recess, so that an intervertebral implant can be introduced into the hollow space. In a further embodiment the anchoring part has an annular construction, while the cross-sectional surface of the hollow space at right angles to the central axis and/or the cross-sectional surface of the anchoring part bordered by the external sheathing surface and at right angles to the central axis may be circular surfaces, elliptical surfaces, oval surfaces or polygonal surfaces. In a preferred embodiment of the intervertebral implant according to the invention it comprises two closing plates at the axial ends, the external surfaces of the closing plates serving the purpose of resting on the cover plate or the base plate of the two adjacent bodies of the vertebra and two anchoring means. The closing plates can be passed through the hollow spaces in the anchoring parts, so that the anchoring parts can be axially displaced relative to the closing plates. The following advantages will be achieved by this: prior to the introduction of the intervertebral implant into the intervertebral space the anchoring parts can be axially displaced until the spikes do not project past the end faces of the closing plates and thus during the introduction of the intervertebral implant into the intervertebral space the adjacent bodies of the vertebra need only a minimal spreading apart, and after the introduction of the intervertebral implant into the intervertebral space both anchoring parts can be displaced with a simple instrument until the spikes are pressed into the base plate or cover plate of the adjacent bodies of the vertebra. In a further embodiment the closing plates are mounted without clearance in the hollow spaces of the anchoring parts and can be displaced relative to the closing plates parallel to the central axis. The advantage of this is that after fixing the anchoring means in the base plate or the cover plate of the adjacent bodies of the vertebra the intervertebral implant does not have any radial clearance. In another embodiment the closing plates comprise second fastening means, in which the fastening means can be engaged on the anchoring parts. These second fastening means can be, for example, that the closing plates of the intervertebral implant have on their sheathing surfaces depressions parallel to the central axis, these depressions serving the purpose of accommodating the lugs of the hooks. The construction with the depressions has the advantage, that by virtue of the lugs snapped into the depressions, the closing plates can be secured against rotation relative to the anchoring parts. In yet another embodiment the fastening means on the anchoring parts have a clearance relative to the second fastening means on the intervertebral implant, in such a manner that in the case of fixed fastening means small rotations of the anchoring parts about the central axis relative to the closing plates are allowed. This will bring with it the advantage, that torsional movements of the adjacent bodies of the vertebra, that are allowed with a certain range, will be allowed by the connection between the anchoring parts and the intervertebral implant. In yet another embodiment the second fastening means are such, that the closing plates have axially projecting segments with reduced diameters, so that the lugs of the hooks can snap in. The method according the invention to fasten an implant, in particular an intervertebral implant on the end plates of both adjacent bodies of the vertebra, basically comprises the following steps: a) enabling the access to the intervertebral space by means of an anterolateral, ventral lateral, transperitonial or retroperitonial surgical procedure, b) tractioning both bodies of the vertebra adjacent to the intervertebral space, c) scraping out the intervertebral space, d) introducing the intervertebral implant with the anchoring means pushed together. On this occasion both anchoring parts are pushed together until the spikes no longer project past the external surfaces of the closing plates, e) moving the anchoring parts axially away from one another until the spikes are adequately pressed into the base plate or the cover plate of the adjacent bodies of the vertebra, and f) fixing the fastening means on the intervertebral implant. In that case when the fastening means are elastically executed, their fixing is carried out automatically without any action by the surgeon as soon as the anchoring parts are moved apart up to their axial end positions. When the fastening means are, however, constructed as screws or similar means, they have to be fixed with a suitable instrument. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The invention and developments of the invention are explained in detail in the following based on schematic illustrations of several embodiments. They show in: FIG. 1 —a section through an embodiment of the anchoring means according to the invention, FIG. 2 —a top view on the embodiment of the anchoring means illustrated in FIG. 1 , FIG. 3 —a section through two anchoring means according to the embodiment illustrated in FIGS. 1 and 2 , provided on an intervertebral implant, FIG. 4 —a detail of a spinal column with an intervertebral implant implanted and two anchoring means according to the embodiment illustrated in FIGS. 1 and 2 , and FIG. 5 —a longitudinal section through an intervertebral implant with two anchoring means according to the embodiment illustrated in FIGS. 1 and 2 . DETAILED DESCRIPTION OF THE INVENTION FIGS. 1 and 2 illustrate a preferred embodiment of the anchoring means 21 according to the invention, that basically comprise an anchoring part 1 with a central axis 6 and a hollow space 3 passing through the anchoring part 1 parallel to the central axis 6 , a plurality, for example four, spikes 7 parallel to the central axis 6 and fastening means 9 . In this case the cross-section of the anchoring part 1 is constructed with a circular cross-section in a plane at right angles to the central axis 6 , but it can have an external and/or internal elliptical, oval, reniform or polygonal design, and has a first end face 4 and parallel to it a second end face 5 . Both end faces 4 , 5 are transversely to the central axis 6 . The four spikes 7 are integral with the anchoring part 1 and are perpendicular to the first end face 4 . The spikes 7 can be, for example, so constructed, that, as it is illustrated here, they taper towards their free end in the axial direction or they can have a point at their free ends or a convex design, so that during the implantation they can be pressed into the end plate of an adjacent body of the vertebra by displacing the anchoring part 1 parallel to the central axis 6 . As fastening means 9 four elastically deformable hooks 10 are provided on the wall 12 of the hollow space parallel to the central axis 6 evenly distributed on the circumference, the lugs 11 of said hooks provided near to the first end face 4 of the anchoring part 3 and protrude into the hollow space 3 . With their lugs 11 the hooks 10 can be detachably snapped into an intervertebral implant 15 , introduced into the hollow space 3 ( FIG. 3 ). The hooks 10 are so arranged in recesses 8 in the wall 12 of the hollow space, that in the case of non-deformed hooks 10 only the lugs 11 protrude transversely to the central axis 6 into the hollow space 3 . Measured perpendicularly to the central axis 6 , the recesses 8 have a depth T, whereas the length of the lugs 11 , also measured perpendicularly to the central axis 6 , is L, while L<T. FIG. 3 shows two identical anchoring means 21 ′, 21 ″, corresponding to the embodiment described in FIGS. 1 and 2 , each of them provided at one end each of an intervertebral implant 15 , whereby the spikes 7 , arranged on the anchoring parts 1 ′, 1 ″, protrude at the end past the end faces 17 of the intervertebral implant 15 . The end faces 17 of the intervertebral implant 15 can be plane, as illustrated here, but they may also dome-shaped. At the same time one anchoring means 21 ′ is illustrated in its second, locked position, while the other anchoring means 21 ″ is in the first position, in which it is pushed parallel to the central axis 6 so far over the intervertebral implant 15 , that the spikes 7 do not protrude past the end face 17 of the intervertebral implant 15 . When introducing an intervertebral implant 15 into the hollow space 3 , the hooks 10 can bend into the recesses 8 , so that the intervertebral implant 15 can be pushed through the hollow space 3 parallel to the central axis 6 and past the lugs 11 . This is illustrated in the form of an example on the anchoring part 1 ″. In the axial direction the closing plates 13 , 14 of the intervertebral implant 15 have at their ends segments 22 with reduced diameters, so that the lugs 11 of the hooks 10 can snap into the shoulder formed by the reduced segments 22 on the closing plates 13 , 14 . This will achieve that the external end faces 17 of the closing plates 13 , 14 will abut against the base plate or the cover plate of the adjacent bodies of the vertebra. Therefore, because the end face 4 of the anchoring part 1 does not abut against the adjacent bodies of the vertebra, it will be ensured that only the intervertebral implant 15 carries the axial load and the load will be transferred to the entire end face 17 . FIG. 4 shows a detail of a spinal column together with an intervertebral implant 15 introduced between two adjacent bodies 19 , 20 of the vertebra. The intervertebral implant 15 is fixed on the end plates of the adjacent bodies 1 , 20 of the vertebra by anchoring means 21 ′, 21 ″, respectively. For fixing the anchoring means 21 ′, 21 ″ on the bodies 19 , 20 of the vertebra the spikes 7 ′, 7 ″ on the anchoring parts 1 ′, 1 ″ are pressed into the end plates of the bodies 19 , 20 of the vertebra. When implanting the intervertebral implant 15 into the scraped out intervertebral space, the anchoring parts 1 ′, 1 ″ are pushed over the intervertebral implant 15 so far, that the spikes 7 will not protrude past the end face 17 of the intervertebral implant 15 ( FIG. 3 ). Only after the intervertebral implant 15 together with two anchoring parts 1 ′, 1 ″ are pushed into the scraped out intervertebral space, will the lower and upper anchoring parts 1 ″, 1 ′ be pushed with an expander against the bodies 19 , 20 of the vertebra adjacent to the intervertebral implant 15 and the spikes 7 pressed into the end plates of the adjacent bodies 19 , 20 of the vertebra. After the spikes 7 had been completely pressed into the end plates and the anchoring parts 1 ′, 1 ″ have reached their end positions, will both hooks 10 ( FIG. 2 ) snap in with their lugs 11 , for example, into the end faces 17 of the intervertebral implant, or into the depressions 18 ( FIG. 5 ), complementing the lugs 11 , on the sheathing surface 16 of the intervertebral implant 15 that is parallel to the central axis 6 . FIG. 5 illustrates an embodiment of an intervertebral implant 15 with anchoring means 21 ′, 21 ″ provided at each axial end. The anchoring means 21 ′, 21 ″ correspond to those described in FIGS. 1 and 2 and comprise an anchoring part 1 ′, 1 ″, respectively, and spikes 7 ′, 7 ″ on the end faces 4 at the axial ends of the anchoring parts 1 ′, 1 ″. The intervertebral implant 15 has at each axial end a closing plate 13 , 14 , while in their cross-section, that is at right angles to the central axis 6 , the construction of the closing plates 13 , 14 is complementary to the hollow spaces 3 of the anchoring parts 1 ′, 1 ″. On the external sheathing surface 16 the closing plates 13 , 14 are provided with depressions 18 , that similarly to the fastening means 9 , are distributed on the circumference of the anchoring parts 1 ′, 1 ″ and have a construction to complement the lugs 11 on the fastening means 9 . Furthermore, the length of the depressions 18 , measured parallel to the central axis 6 , is l, and they open at the axial end into the end surfaces 17 of the closing plates 13 , 14 , that are part of the intervertebral implant 15 . The length l is so dimensioned, that in the case of an axial displacement of the anchoring part 21 ′ 21 ″ relative to the end faces 17 of the intervertebral implant 15 , the lugs 11 of the hooks 10 will snap into the depressions 18 . The externally situated end faces 17 of the intervertebral implant 15 project axially past the end faces 4 of the anchoring parts 1 ′, 1 ″, thus ensuring that the load from both adjacent bodies of the vertebra will be transferred to the intervertebral implant 15 via the end faces 17 . The upper anchoring means 21 ′ is illustrated in this case with snapped in fastening means 9 , whereas the lower anchoring means 21 ″ on the closing plate 14 is pushed so far on the opposite facing closing plate 14 , that the spikes 7 ″ do not protrude past the end face 17 of the intervertebral implant 15 . Similarly to FIG. 3 , the fastening means 9 of the lower anchoring means 21 ″ are deformed transversely to the central axis 6 and pressed into the depressions 8 in the hollow space 3 of the anchoring part 1 ″.	The invention relates to an anchor piece for fixing an intervertebral implant ( 15 ) to the end plate of a vertebra body ( 19;20 ), comprising A) an anchor piece ( 1 ), with a central axis ( 6 ) and two end faces ( 4, 5 ) transverse to the central axis ( 6 ), B) at least two spikes ( 7 ) extending from one of the end faces ( 4;5 ), parallel to the central axis ( 6 ) and which may be pushed into an end plate of a vertebral body ( 19;20 ), whereby B) the anchor piece ( 1 ) has a cavity ( 3 ) extending through the anchor piece ( 1 ) in the direction of the central axis ( 6 ) and C) the anchor piece ( 1 ) comprises fixing means ( 9 ), by means of which the anchor piece may be detachably locked to an intervertebral implant ( 15 ).	5
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to the cleaning of fabrics used in papermaking, and, more particularly, to cleaning fabrics with a low air permeability (i.e., semipermeable membranes). [0003] 2. Description of the Related Art [0004] The need to clean fabrics of papermaking machines is well known. Since the flow of air and/or water through such fabrics is relied upon during the paper forming process, it is desirable that a maximum number of the fluid pathways available in such fabrics remain open. However, during transport of a paper web using such fabrics, various debris that is a by-product of the papermaking process can and does manage to get caught within the fluid pathways of such fabrics. This ongoing collection of debris in a fabric can reduce fluid flow rates therethrough to unacceptable levels and, if collecting near the surface of the fabric, can directly affect the surface quality of the paper being produced. Consequently, the need to effectively clean such fabrics exists. [0005] A variety of methods and devices have already been developed for cleaning fabrics of papermaking machines. It has been disclosed to use different kinds of brushes, air jets and ultrasound spray bars. A rotatable needle jet has also been employed for cleaning fabrics. It has further been suggested to use water spray devices in combination with blowing air to clean a forming wire or screen. [0006] However, these solutions have all been found suitable for cleaning forming wires, press belts and drying fabrics with a high air permeability. These solutions have not been found effective for cleaning low air permeability (i.e., semipermeable) fabrics. In fabrics with high air permeability, the fluid pathways tend to be both numerous and relatively large. As such, debris can be dislodged relatively easily from most such pathways, and there are enough fluid pathways available that it may not always be critical to achieve a high degree of cleanliness for the fabric to operate sufficiently. [0007] However, in semipermeable fabrics, in order to obtain the desired low air permeability therethrough, the number of fluid pathways tend to be limited and/or relatively small, in comparison to high air permeability fabrics. Thus, removal of debris from pathways of semipermeable membranes tends to be much more difficult to achieve, and the margin for error in the number of pathways that can remain blocked and still maintain an acceptable permeability level is much smaller than it is for high air permeability fabrics. [0008] What is needed in the art is an effective method and apparatus for cleaning semipermeable fabrics used in papermaking machines. Specifically, the method and apparatus needs to be vigorous enough to remove a high percentage of debris from a set of openings from which the removal thereof tends to be difficult. SUMMARY OF THE INVENTION [0009] The present invention provides a method and apparatus for cleaning a semipermeable membrane in which a cleaning fluid is applied thereto and then flushed therethrough using an air press to thereby clean the semipermeable membrane. [0010] The invention comprises, in one form thereof, an apparatus for cleaning a semipermeable membrane, the semipermeable membrane being configured for carrying a fiber web. The apparatus includes a source of a cleaning fluid and an applicator configured for applying the cleaning fluid to the semipermeable membrane. The apparatus also includes an air press configured for carrying the semipermeable membrane therethrough. The air press having pressurized air therein is thereby configured for flushing the cleaning fluid through the semipermeable membrane. [0011] The invention comprises, in another form thereof, a method of cleaning a semipermeable membrane, the semipermeable membrane being configured for carrying a fiber web. The method includes the steps of providing a cleaning fluid and applying the cleaning fluid on the semipermeable membrane. Further, an air press configured for carrying the semipermeable membrane therethrough is provided, and the air press has pressurized air therein. The semipermeable membrane is conveyed through the air press and is subjected to the pressurized air within the air press. The pressurized air thereby flushes the cleaning fluid through the semipermeable membrane. [0012] An advantage of the present invention is that it provides an effective way of cleaning a semipermeable membrane having a low air permeability. [0013] Another advantage is that it provides an effective way of cleaning a semipermeable membrane without disturbing paper quality. [0014] Yet another advantage is that the cleaning press of the present invention can be combined with an air press used for dewatering and/or can be used for impregnating/coating the paper web. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: [0016] [0016]FIG. 1 is a side view of a first embodiment of a papermaking machine including an apparatus for cleaning a semipermeable membrane; [0017] [0017]FIG. 2 is a side view of a second embodiment of a papermaking machine including an apparatus for cleaning a semipermeable membrane; [0018] [0018]FIG. 3 is a side view of a third embodiment of a papermaking machine including an apparatus for cleaning a semipermeable membrane; [0019] [0019]FIG. 4 is a side view of a fourth embodiment of a papermaking machine including an apparatus for cleaning a semipermeable membrane; and [0020] [0020]FIG. 5 is a side view of a fifth embodiment of a papermaking machine including an apparatus for cleaning a semipermeable membrane in combination with an air press used for dewatering. [0021] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. DETAILED DESCRIPTION OF THE INVENTION [0022] Referring now to the drawings, and more particularly to FIG. 1, there is shown a papermaking machine 10 configured for cleaning a semipermeable membrane 12 used in a papermaking process. Papermaking machine 10 generally includes a cleaning fluid source 14 , a cleaning fluid applicator 16 , a press 18 and at least one transfer roll 19 . [0023] The cleaning fluid provided by cleaning fluid source 14 is preferably an anionic detergent, a cationic detergent, a surfactant, a soap, a solvent and/or a solvent mixture. The cleaning fluid may include water admixed therewith. [0024] Cleaning fluid applicator 16 is fluidly connected to cleaning fluid source 14 and is positioned adjacent to semipermeable membrane 12 . Cleaning fluid applicator 16 , shown schematically, is preferably a blade coater, a spray device or a transfer coater. Preferably, cleaning fluid applicator 16 is a spray device configured for applying the cleaning fluid under a high gas pressure, most preferably over a region of semipermeable membrane 12 which is greater than the space between adjacent holes therein (not shown). As such, cleaning fluid applicator 16 preferably produces a diverging spray, not a needle jet. [0025] Press 18 is configured both for conveying and pressing semipermeable membrane 12 . The pressing action provided thereby flushes the cleaning fluid through and out of semipermeable membrane 12 . Press 18 includes at least one press roll 20 , one of which is illustrated in FIG. 1. In this embodiment, press roll 20 has positioned thereagainst a doctor blade 22 for removing debris and used cleaning fluid after pressing and cleaning occurs. A trough 26 is positioned below doctor blade 22 for collecting the removed debris and used cleaning fluid. [0026] A second embodiment of the invention, as shown in FIG. 2, discloses a papermaking machine 30 which is capable of both cleaning semipermeable membrane 32 and pressing paper web 34 . Papermaking machine 30 , in addition to semipermeable membrane 32 , includes a permeable layer 36 , a plurality of conveyor rolls 38 , air press 40 and at least one of cleaning fluid sprayers 42 a - 42 d . Papermaking machine 30 may be used solely for cleaning semipermeable membrane 32 or may be used for pressing, coating and/or impregnating paper web 34 , in addition to cleaning of semipermeable membrane 32 and permeable layer 36 . [0027] Semipermeable membrane 32 and permeable membrane 36 are provided for carrying paper web 34 . Semipermeable membrane 32 has a low air permeability specially designed for displacement dewatering. Permeable membrane 36 has a high air permeability and may be a felt, a wire, a press belt, drying fabric or an anti-rewet layer. [0028] Air press 40 includes a first main roll 44 , a second main roll 46 , a first cap roll 48 and a second cap roll 50 , which conjunctively define a pressurized air chamber 52 . The pressure of the air in pressurized air chamber 52 serves to flush the cleaning fluid through semipermeable membrane 32 . The pressure of the air therein is greater than atmospheric pressure (about 1 bar), advantageously more than about 2 bar and preferably greater than approximately 5 bar. First main roll 44 is vented (e.g., blind-drilled, grooved, etc.) so as to promote removal of water, used cleaning fluid and debris from semipermeable membrane 32 . [0029] At least one of cleaning fluid sprayers 42 a - 42 d is provided as part of papermaking machine 30 . Cleaning fluid sprayer 42 a is directed toward semipermeable membrane 32 from a position just upstream of air press 40 , relative to web travel direction 35 . Cleaning fluid sprayer 42 b extends into pressurized air chamber 52 and is configured to deliver cleaning fluid onto semipermeable membrane 32 from within pressurized air chamber 52 . Cleaning fluid sprayer 42 c is located adjacent to second cap roll 50 . Cleaning fluid sprayer 42 c and second cap roll 50 together are configured to act as a transfer coater for indirectly delivering cleaning fluid onto semipermeable membrane 32 . Similarly, cleaning fluid sprayer 42 d and first cap roll 48 together also function as a transfer coater. [0030] In yet another embodiment, papermaking machine 60 (FIG. 3) includes a semipermeable membrane 62 and a permeable membrane 64 for carrying a paper web 66 , an air press 68 , a cleaning fluid applicator 70 and conveyor rolls 72 . [0031] Air press 68 includes a box arrangement 74 mounted adjacent a suction roll 76 . Box arrangement 74 and suction roll 76 coact to form an entrance nip 78 and an exit nip 80 therebetween, respectively through which semipermeable membrane 62 , permeable membrane 64 and paper web 66 are fed into and out of air press 68 . Box arrangement 74 and suction roll 76 together define an air pressure chamber 82 . Box arrangement 74 has an air inlet line 84 associated therewith for introducing air under pressure into air pressure chamber 82 . Conversely, suction roll 76 is provided with a vacuum line 86 for creating a negative pressure therein. [0032] Cleaning fluid applicator 70 is positioned prior to entrance nip 78 , relative to a web travel direction 87 , and adjacent semipermeable membrane 62 . Cleaning fluid applicator 70 includes a sprayer 88 and an applicator roll 90 . Sprayer 88 delivers cleaning fluid 92 onto applicator roll 90 which, in turn, transfers cleaning fluid 92 to semipermeable membrane 62 . Alternatively or additionally to cleaning fluid applicator 70 , a cleaning fluid dispenser (not shown) could be provided within air pressure chamber 122 , in a manner similar to cleaning fluid sprayer 42 b in FIG. 2. [0033] A further embodiment of the invention is shown in FIG. 4. Specifically, papermaking machine 100 includes a semipermeable membrane 102 and a permeable membrane 104 for carrying a paper web 106 , an air press 108 , a cleaning fluid sprayer 110 and conveyor rolls 112 . [0034] Air press 108 includes a box arrangement 114 mounted adjacent a press shoe 116 . Box arrangement 114 and press shoe 116 coact to form an entrance nip 118 and an exit nip 120 therebetween, respectively through which semipermeable membrane 102 , permeable membrane 104 and paper web 106 are fed into and out of air press 108 . Box arrangement 114 and press shoe 116 together define an air pressure chamber 122 . Box arrangement 114 has an air inlet line 124 associated therewith for introducing air under pressure into air pressure chamber 122 . Conversely, press shoe 116 is provided with a vacuum line 126 for creating a negative pressure therein. Additionally or alternatively to cleaning fluid sprayer 110 , a cleaning fluid dispenser (not shown) could be provided within air pressure chamber 122 in a manner similar to cleaning fluid sprayer 42 b in FIG. 2. [0035] A yet another embodiment is set forth in FIG. 5. Papermaking machine 130 includes a semipermeable membrane 132 and a permeable membrane 134 for carrying a paper web 136 , a two-stage air press 138 and conveyor rolls 140 . [0036] Two-stage air press 138 is a cluster press that includes a first main roll 142 , a second main roll 144 , a third main roll 146 and four cap rolls 148 . Preferably, first main roll 142 and second main roll 144 are vented in order to promote removal of water, used cleaning fluid (initially applied in a manner shown in FIGS. 1 - 4 ) and/or debris. Stage one 150 of two-stage air press 138 is defined by first main roll 142 , second main roll 144 and a pair of cap rolls 148 . Stage one 150 has a first air chamber 152 associated therewith. In the embodiment illustrated, semipermeable membrane 132 is fed into first air chamber 152 adjacent first main roll 142 to maximize the time spent thereby in first air chamber 152 . Conversely, permeable membrane 134 and paper web 136 are fed in later, adjacent to second main roll 144 . [0037] Stage two 154 is defined by second main roll 144 , third main roll 146 and a pair of cap rolls 148 . Stage two 154 has a second air chamber 156 associated therewith. In two-stage air press 138 , first air chamber 152 is for cleaning, and second air chamber 156 is for dewatering. [0038] Stage one 150 has at least one of a first flushing direction 158 and a second flushing direction 160 associated therewith, and stage two 154 has an associated dewatering direction 162 . First flushing direction 158 and second flushing direction 160 are directed at first main roll 142 and second main roll 144 , respectively, within first air chamber 152 . Dewatering direction 162 extends toward second main roll 144 from inside second air chamber 156 . First flushing direction 158 is substantially the same as dewatering direction 162 (relative to the orientation of papermaking machine 130 ) but is substantially diametrical to second flushing direction 160 . Each direction 158 , 160 and 162 signifies movement of fluid from a high pressure chamber side toward one of vented main rolls 142 and 144 . Stage one 150 may be chosen to be operated in first flushing direction 158 and/or second flushing direction 160 in order to achieve high cleanliness, especially if there are stickies in the pulp. [0039] In cleaning semipermeable membrane 32 , a cleaning fluid is provided and is applied on semipermeable membrane 32 . Air press 40 is provided and has pressurized air therein. Semipermeable membrane 32 is conveyed into air press 40 and is subjected to the pressurized air therein. The pressurized air flushes the cleaning fluid through semipermeable membrane 32 , thereby cleaning semipermeable membrane 32 . [0040] While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.	A method of cleaning a semipermeable membrane, the semipermeable membrane being configured for carrying a fiber web, includes the steps of providing a cleaning fluid and applying the cleaning fluid on the semipermeable membrane. Further, an air press configured for carrying the semipermeable membrane therethrough is provided, and the air press has pressurized air therein. The semipermeable membrane is conveyed through the air press and is subjected to the pressurized air within the air press. The pressurized air thereby flushes the cleaning fluid through the semipermeable membrane.	3
BACKGROUND OF THE INVENTION This invention relates generally to an apparatus for conveying railroad tie plates placed thereon from the bed of a railroad track mounted highway truck or railroad car to the bed of a railroad track in a predetermined and spaced apart sequence as the apparatus and the truck or car move in unison along the track. Machines which apply or drive tie plates to or on railroad ties have long been known in the prior art. See, for example, U.S. Pat. No. 567,232 granted to W. H. Greenshield on Sep. 8, 1896, U.S. Pat. No. 594,731 granted to G. W. Dowe on Nov. 30, 1897 and U.S. Pat. No. 636,702 granted to G. R. Wilton on Nov. 7, 1899. These and other such patents relate to machines which affix or secure tie plates to railroad ties. But there has been a long felt need in the railroad art for an apparatus which can deposit tie plates, one at a time, on and along the bed of a railroad track at convenient spaced apart positions so that, later, as old railroad rails and tie plates are removed, the previously deposited new tie plates can be readily handled and substituted in place of the old tie plates, preparatory to laying new rails. Since each railroad tie requires a pair of such tie plates, one under each rail, it would be convenient to deposit one of such pair of replacement tie plates on a tie, centered between the rails, and the other, so as to be approximately centered between that tie and the next succeeding tie and also centered between the rails. According to the present custom, ties are located on successive longitudinal centerlines which are about 22 inches apart on a straight course of track in the United States. Thus, it would be desirable to provide an apparatus for depositing such replacement plates about eleven inches apart along the centerline of a railroad track. This will readily permit a worker to reach any two successively deposited tie plates for replacement of the two old tie plates on a nearest one of the railroad ties, preparatory to replacing the rails thereon. By means of my invention, this particular long felt need in the prior art can now be met. SUMMARY OF THE INVENTION It is an object of my invention to provide an apparatus and method for conveying railroad tie plates from storage on a railroad track mounted carrier to the bed of a railroad track in a predetermined, spaced apart sequence as the apparatus and carrier move in unison along the track. Briefly, in accordance with this object, a method for depositing tie plates in a spaced apart sequence along a bed of a railroad track from a mobile tie plate carrier mounted on the track is provided. The steps of the method include providing a gravity feed roller conveyor, an upper end portion of which is mounted in a tie plate receiving position on the carrier. A lower tie plate discharging end portion of the roller conveyor is attached to support structure carried by a pair of railroad wheels mounted on the track for movement with the carrier. The method further includes loading the plates, one after another, on the upper end portion of the roller conveyor such that the tie plates gravitate toward the lower end portion. The method also includes capturing each of the tie plates separately and in sequence as it gravitates down the roller conveyor to a preselected position on the roller conveyor near a discharge end of the lower end portion. The method additionally includes releasing each of the tie plates, following the step of capturing it, at a predetermined rate which depends on the distance traveled along the track by the pair of wheels since release of an immesiately preceding one of the tie plates such that successive ones of the tie plates can gravitate off of the discharge end onto the track bed at predetermined spaced apart positions as the carrier and conveyor move along the track. These and other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and attached drawings which, by way of example, only a preferred embodiment of my invention is explained and illustrated. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a side elevation view of a conventional railroad track mounted highway truck containing and towing a novel apparatus for unloading tie plates from the truck along a railroad track, thus illustrating a preferred embodiment of my invention. FIG.2 shows a side elevation view of a conventional open top railroad car containing and towing the same tie plate unloading apparatus as shown in FIG. 1 . FIG. 3 shows a top plan view of a tie plate unloading end portion of the apparatus of FIGS. 1-2. FIG. 4 shows a cross-sectional view of a portion of the apparatus of FIGS. 1-3, as viewed along cross-section lines 4 — 4 of the latter-mentioned figure. FIG. 5 shows a cross-sectional view of another portion of the apparatus of FIGS. 1-4, as viewed along cross-section lines 5 — 5 of FIG. 3 . FIG. 6 shows a cross-sectional view of yet another portion of the apparatus of FIGS. 1-5, as view along cross-section lines 6 — 6 of FIG. 3 . FIG. 7 shows a cross-sectional view of still another portion of the apparatus of FIGS. 1-6, as viewed along cross-section lines 7 — 7 of the latter mentioned figure. FIG. 8 . shows a peripheral view of a railroad wheel and portions of the support structure of the apparatus of FIGS. 1-7, as viewed along viewing lines 8 — 8 of FIG. 6, with a certain part torn away for viewing internal structure. FIG. 9 shows a side elevation view of a tie loading end portion of the apparatus of FIGS. 1-8 projecting from a rear end portion of the truck of FIG. 1 . FIG. 10 shows a top plan view of a tie loading end portion of the apparatus of FIGS. 1-9 mounted on a bed of the truck of FIG. 1 . DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing figures, there is shown in a preferred embodiment of my invention, a conveyor apparatus, generally designated 12 , for sequentially unloading railroad tie plates 14 from a suitable tie plate carrier, such as a railroad track mounted truck 16 , as shown in FIG. 1, or a modified box car 18 as shown in FIG. 2 . As best shown in FIG. 3, the. apparatus 12 is adapted to deposit the plates 14 along a railroad track 20 . More specifically, I prefer to adapt the apparatus 12 to deposit one of the plates 14 every eleven inches along a centerline of the track 20 . Conventionally, a straight portion of the track 20 will have cross ties 22 laid on longitudinal centerlines which are about twenty two inches apart, as measured along track rails 24 . The apparatus 12 will then deposit every other one of the plates 14 on each of the cross-ties 22 , as at 14 a in FIG. 3, and the remaining plates mid-way between each of the ties, as at 14 b in FIG. 3 . An individual workman who follows behind the apparatus 12 will then find it easy to reach any adjacent pairs of the plates 14 to replace old tie plates on each individual tie 22 after the old rails 24 have been removed, preparatory to placement of new rails on the newly placed tie plates. The conveyor apparatus 12 includes a tie loading end portion, which is mounted on the bed 26 of the truck 16 , for example, as is shown best in FIGS. 9-10, and a tie unloading end portion which is supported on railroad wheels 28 , as best shown in FIGS. 1, 2 and 3 . The tie loading end portion of the apparatus 12 can include a conventional motorized endless belt conveyor, generally designated 30 , for transporting the plates 14 rearwardly (from right to left, as viewed) from a front and mid-portion to a rear portion of the truck bed 26 . The conveyor 30 can be positioned at a convenient height above the bed 26 so that one or, perhaps, two workers 31 (FIG. 10) standing on opposite sides of the conveyor 30 , can readily pick up the tie plates 14 from storage along each side of the bed 26 (See FIG. 10 ), place them on the moving belt conveyor 30 and, preferably, orient them for disposition on the track 20 as shown in FIG. 3. A drive motor 32 for the belt conveyor 30 can be of the usual 12 vdc electric type so as to be energized by an engine driven electrical system of the truck 16 . But, in order to avoid overtaxing a battery of the truck 16 , it is preferred to use a separate gasoline powered motor/generator set 33 (See FIG. 10) to power a 120 vac drive motor 32 of the belt conveyor 30 . Where the box car 18 of FIG. 2 is used for carrying the loading end portion of the apparatus 12 , a suitable gasoline powered motor/generator set, can also be used as a satisfactory energy source for the drive motor of the conveyor 30 . The belt conveyor 30 delivers the tie plates 14 onto an upper input end 34 of a diagonally downwardly and rearwardly sloping gravity feed, roller conveyor, generally designated 36 . The slope of the gravity feed roller conveyor 36 is suitable at about 10 to 15 degrees from horizontal. The roller conveyor 36 includes a series of parallel and closely spaced apart cylindrically shaped rollers 38 of conventional type which are freely rotatable about their longitudinal axes, as for example, on conventional bearings. The rollers 38 are suitably journaled in opposing and parallel extending side beams 39 , which may be angle irons. The tie plates 14 thus are conveyed by gravity along the rollers 38 until intercepted by a device such as, for example, an inflatable pneumatic tire 40 . The tire 40 is mounted above a central part of several of the rollers 38 and is connected by a gear chain 42 to an axle 44 of the railroad wheels 28 for rotation as a function of rotation of the railroad wheels. In the present example, the tire 40 can be a standard inflatable go cart slick, having 5½ inches in tread width and 6 inches in radius. In the alternative, an inclined chute with a metal base could be substituted in place of the roller conveyor 36 provided it is operatively inclined at a sufficient angle to assure that the tie plates 14 placed on an upper input end thereof will readily slide downwardly along the base for individual capture by the tire 40 and subsequent release to the track bed. Clearly, the angle of incline in such a chute would need to be greater than that of the roller conveyor 36 . The tire 40 rotates with the railroad wheels 28 but in an angular direction which is opposite that of the rollers 38 when transporting the tie plates 14 thereon. As the tie plates 14 are gravity fed down the rollers 38 , a tread of the tire 40 engages and bears downwardly on one of the plates at a time, thus pinning or capturing that plate against the underlying rollers. Upon initial engagement of the tire 40 with a given one of the plates 14 , the tire must rotate a full 360 degrees on its axle 46 each time the railroad wheels 28 move the desired tie plate drop distance, i.e. every eleven inches in the present example, along the rails 24 where the tie plates are to be replaced under both of the rails 24 or every twenty two inches where the tie plates under only one of the rails are to be replaced. In this way, a different one of the tie plates 14 will pass completely under and become released from contact with the tire 40 each time the wheels 28 have moved eleven or twenty two inches along the tracks 24 , as the particular case requires. After release of each of the plates 14 by the tire 40 , the plate freely gravitates off of a lower output end of the roller conveyor 36 for disposition along a centerline of the tracks 24 . 1 recommend that a discharge end of the roller conveyor 36 be positioned at a height of about 3 - 4 inches above the track bed such that the plates will not flip over or bounce out of the alignment as shown (FIG. 3 ). Accordingly, once the apparatus 12 is indexed so as to drop one of the plates 14 , either on one of the ties 22 , or mid-way between two adjacent ties, and the tire 40 is adjusted to make one full rotation while the wheels 28 are traveling a desired plate drop distance along the rails 24 the plates will thereafter be discharged with the desired spacing. The apparatus 12 will deposit all other ones of the plates 14 at the desired locations and with the desired spacing. As shown in FIG. 3, the plates 14 gravitating down the roller conveyor 36 will usually back up in front of the tire 40 , one next to another, depending on how rapidly such plates are loaded onto the belt conveyor 30 and how rapidly the belt conveyor is moving to discharge them onto the roller conveyor. It may be necessary to adjust the speed of travel of the belt conveyor 30 to synchronize closer to the speed of rotation of the tire 40 , and, hence, the speed of rotation of the wheels 28 in order to prevent the plates 14 from backing up along the roller conveyor 36 in front of the tire all the way to the input end 34 . A back-up of, say, about four of the plates 14 in front of the tire 40 at all times should assure even spacing between the plates being deposited along the track 20 . Of course, sometimes the back-up might grow to seven or eight of the tie plates 14 while at other times the back-up might drop as low as two or three. A visual inspection of the back-up by workers standing in the bed 26 of the truck 16 will readily determine whether their rate of loading the tie plates 14 on the belt conveyor 30 is too great or too small or whether the speed of the belt conveyor 30 or, for that matter, the speed of the truck 16 along the track 20 should be increased or decreased. In many cases, merely reducing the rate at which the tie plates 14 are being placed on the conveyor 30 by the workman will prevent back up of the plates behind the tire 40 from becoming too great. The side beams 39 at the upper end 34 of roller conveyor 36 are welded to a pair of angles 48 which are, in turn, bolted to an upper end portion of a pair of parallel and spaced apart support rails 50 . See FIGS. 9-10. The beams 50 are welded on the upper end of support beams 52 which are, in turn, bolted to a rear end portion of a frame 54 of the truck 16 upon which a rear fender 56 is mounted. The belt conveyor 30 includes metal side panels 58 . A series of support beams 60 are welded to the side panels 58 for supporting the belt conveyor at a convenient height above the truck bed 26 . Parallel side walls 62 extending above and being welded to the side panels 58 assure that the tie plates 14 being placed on the belt conveyor 30 will not fall over the sides thereof and will be fed to the output end thereof for disposition on the rollers 38 at the upper input end of the roller conveyor 36 . A plywood sidewall 64 secured to a series of spaced apart upright metal posts 66 encloses the truck bed 26 and extends along opposite sides, across a front end and under an output end of the belt conveyor 30 . The posts 66 are of conventional type having metal plates at the base to accommodate bolts for fastening them to the truck bed 26 in any suitable manner. Referring now specifically to FIGS. 3-4, the chain 42 can be of the endless bicycle type and is strung between a follower sprocket 65 , mounted for rotation on and with the axle 46 , and a drive sprocket 67 , mounted for rotation on and with the drive axle 44 of the wheels 28 . Tension in the chain 42 can be increased or decreased by movement of a suitable tension gear 68 along an elongated slot 70 formed through a plate 71 and an opposing side of a channel member 72 . The plate 71 is welded to the opposing side of the channel 72 and the latter is, in turn, seated upon and welded to an upper surface of one of the side beams 39 nearest the chain 42 . As best seen in FIG. 3, a portion of the channel 72 and the attached plate 71 project outwardly away from a side of the beam 39 to which they are connected to assure clearance of the chain 42 and sprockets 65 , 67 from that beam. A bolt 73 extends through the tension gear 68 and the slot 70 in the plate 71 and opposing side of the channel 72 . By loosening the bolt 73 , it and the tension gear 68 can be moved along the slot 70 to increase or decrease tension in the chain 42 . By removing the effect of the tension gear 68 on the chain 42 , as by loosening its bolt 73 and sliding it and tension gear along the slot 70 , fully to the right as viewed, the chain 42 can be loosened and removed from the sprockets 65 and 67 . By moving the bolt 73 and the tension gear 68 toward the left, as viewed, the chain 42 can be tightened to render it operative on the sprockets 65 and 67 , as in the position shown in FIG. 4 . The bolt 73 is then tightened to secure it and the tension gear 68 in the desired operative position against the chain 42 . Referring now to FIGS. 3 and 5 - 8 , a support structure, generally designated 75 , for supporting a lower output end portion of the roller conveyor 36 over the railroad wheels 28 and axle 44 is shown. A lower surface of the roller conveyor side beams 39 rests essentially flush on an upper side of an elongated channel member or cross beam 76 . The cross beam 76 is welded, bolted or otherwise suitably secured to the underside of the two side beams 39 at their intersections. Opposite ends of the cross beam 76 are welded to opposing sides 78 of a pair of channel elements 80 , each of which elements is located partially within a different one of the wells of the wheels 28 (See FIG. 8 ). The cross beam 76 thus extends parallel to and spaced apart from the axle 44 of the wheels 28 . Upper and lower end portions of each of the channel elements 80 are, in turn, removably connected, as by bolts 82 , to a pair of angle brackets 84 . See FIGS. 5-7. Each of the angle brackets 84 have a triangularly shaped side plate 86 , located in planes parallel to the tracks 24 , and a rectangular shaped front plate 88 extending at a right angle to the side plate 86 . The front plates 88 mount flush against upper and lower rear surfaces of the channel elements 80 and are adjoined thereto by the bolts 82 as previously indicated. The side plates 86 are welded to opposing edges of a rectangular plate 90 (See FIGS. 5 - 7 ), each of the rectangular plates thus lying in the same plane between pairs of the adjoining side plates. A bearing housing 92 , through which the wheel axle 44 extends, is welded to each of the plates 90 and its translational position along the axle 44 , together with that of the remaining attached support structure 75 , is held in fixed position by bolted ring clamps 93 (See FIG. 6 ). While the axle 44 rotates with the wheels 28 , the support structure 75 remains fixed in the position shown with the wheel axle rotating therethrough on bearings 96 . Although the present invention has been shown and described with respect to specific details of a certain preferred embodiment thereof, it is not intended that such details limit the scope and coverage of this patent other than as expressly set forth in the following claims, taking into consideration modifications which are equivalent thereto.	An apparatus partially carried on and partially towed behind a railroad track mounted highway truck or box car for conveying tie plates from the truck or car for deposit in a predetermined spaced apart sequence along the bed of a railroad track as the truck or car and the apparatus move in unison along the track. A method executed by this apparatus is also disclosed.	4
BACKGROUND OF THE INVENTION Two pipe ends can be joined easily when the pipes are very flexible in bending. Some pipe materials are more flexible than others, e.g., rubber hoses are more flexible than steel pipe, and small diameter pipes are more flexible than larger diameter pipes. Generally, for a given material, the flexibility of the pipe is proportional to the cube of the diameter of the pipe. Large pipes, for example 18-60 inches in diameter, are so stiff that field bends usually are not feasible, and bends are made in these pipes in special plants designed for this purpose. In the case of submarine pipeline joints made on-bottom, it is difficult to both manipulate and align the ends of large diameter pipes for joining because such pipes are stiff axially as well in bending. Remote control operations and handling of massive equipment from surface vessels also add substantially to the difficulties of these problems. Accordingly, the present invention provides a new and useful flexible element which substantially alleviates or overcomes the above noted problems of the prior art and provides further advantages as will be more apparent hereinafter. SUMMARY OF THE INVENTION The present invention pertains to a flexible element useful for joining pipelines, which element can be used to make a length of pipe more flexible axially, as well as in bending. The flexible element can be used in submarine pipelaying (where pipe alignment is difficult) to add flexibility to the line at discrete locations along the length thereof. This would assist, for example, in joining two strings of pipe together by welding or by using mechanical connectors. One specific use is in bringing two flanges together. If there is a rotational (bending) misalignment between the flanges, the flexible element can make it easier to achieve the required rotation thereby permitting clamping of the flanges. If there is an axial gap between flanges, the flexible element can reduce the force required to close this gap. More specifically, the present invention pertains to a flexible length of pipe composed of at least two pipe sections joined by a flexible element disposed between the ends of the two pipe sections. The flexible element may have somewhat open configurations such as that of a toroid with a semi-circular cross section or other forms of a cylindrical shell with at least one convolution around the circumference attached to the pipe ends to form a pressure-tight joint. The flexible element can thus be thought of as a ring-like section approximating a short joint of pipe, attached between two pipe ends. If the flexible element (ring) were, in fact, a short joint of pipe it would be no more flexible than the pipe. If the ring cross section is curved or convoluted, then the ring becomes more flexible in the pipe axis direction. This is because the element flexes in bending in addition to stretching. And, the bending flexure is much greater than stretching alone. Also, the flexible ring element may have an open-sided rectangular cross section and join the pipe sections so that the innermost parts of the ring connect with the pipe ends. A solid insert such as a solid ring or other inserts which are lined up like a ring may be utilized adjacent to the convolutions (inside or outside of the flexible element) to prevent the deformation of the element beyond a prescribed amount. Other features of the invention will be apparent from the following description. DESCRIPTION OF THE DRAWING FIG. 1 shows a profile of two pipe ends connected by a circular toroidal element. The reduced pipe diameter of this basic concept makes it less preferred than some of the embodiments following. FIG. 2 depicts an exaggerated deformation of the toroidal element due to bending moment in the pipe. FIG. 3 shows a toroid made of larger mean diameter so that its minimum diameter is at least equal to the pipe inside diameter. FIG. 4 discloses other more preferred forms of the flexible element such as a semi-circular shape in FIG. 4(a) and a straight line version in FIG. 4(b). FIG. 5 shows a version of the element using a wide interior shell-like ring with ridges on each end to limit deformations. FIG. 6 provides an embodiment wherein flexible elements are incorporated as part of a three-point bending frame. FIGS. 7 and 8 show a ring insert of varying cross-sectional area around the circumference thereof. FIGS. 9 and 10 provide views of an insert which is multiple straight rods. FIGS. 11 and 12 depict an insert which is multiple pipe segments. FIGS 13 and 14 show an insert of multiple balls. DESCRIPTION OF PREFERRED EMBODIMENTS The present invention pertains to a flexible element for joining pipelines, useful for making a length of pipe more flexible axially as well as in bending, depending upon the exact design of the pipeline. It is useful particularly in submarine pipelaying to add flexibility to the line at discrete locations along the length thereof to assist, for instance, in the joining of two strings of pipe together by mechanical connectors or by welding. It also can be used to bring flanges together, or in the event that there is a rotational misalignment, the element can make it easier to achieve rotation to permit clamping of the pipes. Similarly, if there is an axial gap between flanges, a flexible element reduces the force required to close the gap. In addition, another application of the flexible element of the invention is to compensate for thermal effects on pipelines, thereby acting as an axial contraction or expansion joint. Internal inserts and/or external and internal clamps can be used to limit the rotation and axial elongation occurring. Referring to the drawings, FIG. 1 provides a profile of two pipe ends connected by a circular toroidal element of diameter equal to that of the pipe. Thus, toroid 1 is placed between pipe end 2 and pipe end 3. A solid insert 4 is placed inside the toroid 1. Such inserts, frequently solid rod segments, limit the deformation of the toroid produced by axial or bending loads in the pipe. Exaggerated deformation of the toroidal flexible element 1 is shown in FIG. 2. This deformation is due to a bending moment in the pipeline. Inserts 4 stop the ovalling of the toroid once the prescribed amount occurs. The inserts preclude buckling of the toroid and produce a stiffness condition similar to that of a bent pipe without a flexible element. In a similar manner, a toroidal flexible element can be used to flex due to axial loads. Of course, flexing may be due to the combined effects of axial and bending loads as well. In normal pipeline operations, it frequently is desirable to pass a cleaning ball or cylindrical "pig" through the line without obstruction. For this operation to be effected with the present invention, the toroid must be of larger mean diameter so that its minimum diameter is at least equal to the pipe diameter. The eccentric toroid of FIG. 3 accomplishes this purpose. It will be noted that pipeline 30 has a bell shaped end 31 which allows the toroidal element 1 and insert 4 to be placed outside of the diameter of the pipe which, of course, allows pigs or other cleaning elements to be passed through the pipe without obstruction. Insert 4 can be a ring-shaped rod or a thick-walled pipe. Alternatively, the insert can be multiple straight rod or pipe elements, of short enough lengths to minimize curvature effects, or even multiple balls. If it is desired to prevent axial deformation while permitting bending deformation in a predetermined plane, the multiple balls, rods, pipes, etc. may be of varying diameters. In yet another embodiment, a previously flexed joint can be rigidized by filling the flexible toroid with a grouting medium such as epoxy or concrete. Buckling or deformation of the toroid can also be controlled by fluid filling and/or by pre-pressurization. If, however, rigid inserts are used, the toroid can be vented to the inside of the pipe or to the outside of the pipe, depending on the ratio of internal and external pressures, in order to minimize principal stresses and thus minimize fatigue damage due to fluctuations in internal pressure. FIGS. 4(a) and 4(b) show other more flexible and potentially more useful versions of the flexible element other than the eccentric toroid of FIG. 3, which may be employed in order to permit passing of a pig or cleaning ball through a pipeline. In FIG. 4(a) the flexible element 40 has a semi-circular convoluted shape and the insert 41 has a shape similar to that of the toroid. The diameter of pipeline 42 is thus the same as the minimum diameter of the semi-circular shape and insert. An alternative embodiment is shown in FIG. 4(b) which employs a flexible element having a flat-sided rectangular cross section 43 and has a solid insert ring 44 which is similar in shape to the rectangular flexible element. FIG. 5 shows a version of the flexible element using a wide internal retaining ring 50 instead of the narrower inserts previously described. Ring 50 has ridged ends which fit into grooves 51 and 52 inside the pipe on both sides of the flexible element 53. Thus, the ring replaces previously dedcribed inserts which would not be effective in tension. External mechanical ring clamps, not shown, fitting around and outside the convolution or convolutions may be employed to limit deformations. Flexible elements as shown in the above described figures can also be incorporated as part of a three point bending frame as shown in FIG. 6 so that bending energy can be applied to achieve rotation. The distortion can be limited and then locked in by the loading means. Pipe 60 extends through three point frame 61, and flex element 62 is held in place by loading means 63 such as a pair of hydraulic jacks. The jacks can be self-locking or otherwise locked to prevent subsequent movements of the joint. The flexible elements or convolutions of the present invention can be utilized in series, using any of the previously described variations in order to solve any problem connected with laying pipelines in the event that a single flexible element is insufficient to produce the required bending or axial flexing of the line. Other combinations of the above described elements will be evident to those skilled in the art without exercise of invention beyond that above described.	A flexible length of pipe is formed from at least two pipe sections joined by a flexible element such as a closed toroidal shell or open convoluted forms.	5
RELATED APPLICATIONS [0001] This application derives benefit from provisional application No. 60/909,473, filed Apr. 1, 2007, the entirety of which is incorporated by reference. FIELD [0002] The described devices are spinal implants that may be surgically implanted into the spine to replace damaged or diseased discs using a posterior approach. The discs are prosthetic devices that approach or mimic the physiological motion and reaction of the natural disc. BACKGROUND [0003] The intervertebral disc is an anatomically and functionally complex joint. The intervertebral disc is composed of three component structures: (1) the nucleus pulposus; (2) the annulus fibrosus; and (3) the vertebral end plates. The biomedical composition and anatomical arrangements within these component structures are related to the biomechanical function of the disc. [0004] The spinal disc may be displaced or damaged due to trauma or a disease process. If displacement or damage occurs, the nucleus pulposus may herniate and protrude into the vertebral canal or intervertebral foramen. Such deformation is known as herniated or slipped disc. A herniated or slipped disc may press upon the spinal nerve that exits the vertebral canal through the partially obstructed foramen, causing pain or paralysis in the area of its distribution. [0005] To alleviate this condition, it may be necessary to remove the involved disc surgically and fuse the two adjacent vertebrae. In this procedure, a spacer is inserted in the place originally occupied by the disc and the spacer is secured between the neighboring vertebrae by the screws and plates or rods attached to the vertebrae. Despite the excellent short-term results of such a “spinal fusion” for traumatic and degenerative spinal disorders, long-term studies have shown that alteration of the biomechanical environment leads to degenerative changes particularly at adjacent mobile segments. The adjacent discs have increased motion and stress due to the increased stiffness of the fused segment. In the long term, this change in the mechanics of the motion of the spine causes these adjacent discs to degenerate. [0006] Artificial intervertebral replacement discs may be used as an alternative to spinal fusion. SUMMARY [0007] Prosthetic intervertebral discs and methods for using such discs are described. The subject prosthetic discs include an upper end plate, a lower end plate, and a compressible core member disposed between the two end plates. The compressible core may be extendible, in place, by twisting the core to achieve a desired height. The described prosthetic discs have shapes, sizes, and other features that are particularly suited for implantation using minimally invasive surgical procedures, particularly from a posterior approach. [0008] In one variation, the described prosthetic discs include top and bottom end plates separated by one or more compressible core members. The two plates may be held together by at least one fiber wound around at least one region of the top end plate and at least one region of the bottom end plate. The described discs may include integrated vertebral body fixation elements. When considering a lumbar disc replacement from the posterior access, the two plates are preferably elongated, having a length that is substantially greater than its width. Typically, the dimensions of the prosthetic discs range in height from 8 mm to 15 mm; the width ranges from 6 mm to 13 mm. The height of the prosthetic discs ranges from 9 mm to 11 mm. The widths of the disc may be 10 mm to 12 mm. The length of the prosthetic discs may range from 18 mm to 30 mm, perhaps 24 mm to 28 mm. Typical shapes include oblong, bullet-shaped, lozenge-shaped, rectangular, or the like [0009] The described disc structures may be held together by at least one fiber wound around at least one region of the upper end plate and at least one region of the lower end plate. The fibers are generally high tenacity fibers with a high modulus of elasticity. The elastic properties of the fibers, as well as factors such as the number of fibers used, the thickness of the fibers, the number of layers of fiber windings in the disc, the tension applied to each layer, and the crossing pattern of the fiber windings enable the prosthetic disc structure to mimic the functional characteristics and biomechanics of a normal-functioning, natural disc. [0010] A number of conventional surgical approaches may be used to place a pair of prosthetic discs. Those approaches include a modified posterior lumbar interbody fusion (PLIF) and a modified transforaminal lumbar interbody fusion (TLIF) procedures. We also describe apparatus and methods for implanting prosthetic intervertebral discs using minimally invasive surgical procedures. In one variation, the apparatus includes a pair of cannulae that are inserted posteriorly, side-by-side, to gain access to the spinal column at the disc space. A pair of prosthetic discs may then be implanted by way of the cannulae to be located between two vertebral bodies in the spinal column. [0011] The prosthetic discs may be configured by selection of sizes and structures suitable for implantation by minimally invasive procedures. [0012] Other and additional devices, apparatus, structures, and methods are described by reference to the drawings and detailed descriptions below. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The Figures contained herein are not necessarily drawn to scale. Some components and features may be exaggerated for clarity. [0014] FIG. 1 shows a method for placement of prosthetic intervertebral discs using a posterior approach. [0015] FIG. 2 is a perspective view of a variation of my prosthetic disc. [0016] FIG. 3 is a cross-sectional side view of an end plate used in the FIG. 2 variation of my prosthetic disc. [0017] FIG. 4A is a side view of one variation of a compressible core for use with my disclosed disc. [0018] FIG. 4B is a top view of the FIG. 4A compressible core. [0019] FIG. 5 is a side view of another variation of a compressible core for use with my disclosed disc. [0020] FIG. 6 is a cross-sectional side view of another end plate variation. [0021] FIG. 7 is a side view of another variation of a compressible core for use with my disclosed disc. [0022] FIG. 8 is a cross-sectional side view of another end plate variation. [0023] FIG. 9 is a side view of another variation of a compressible core for use with the end plates of FIG. 8 . [0024] FIG. 10 is a cross-sectional side view of another end plate variation. [0025] FIG. 11 is a side view of another variation of a compressible core for use with the end plates of FIG. 10 . [0026] FIG. 12A is a side, partial, cross-sectional view of another variation of my prosthetic disc. [0027] FIG. 12B is a top view of the disc shown in FIG. 12A . [0028] FIG. 12C is a side view of the disc shown in FIG. 12A . [0029] FIG. 13 schematically illustrates a method for implanting the described prosthetic discs. DETAILED DESCRIPTION [0030] Described below are prosthetic intervertebral discs, methods of using such discs, apparatus for implanting such discs, and methods for implanting such discs. It is to be understood that the prosthetic intervertebral discs, implantation apparatus, and methods are not limited to the particular embodiments described, as these may, of course, vary. It is also to be understood that the terminology used here is only for the purpose of describing particular embodiments, and is not intended to be limiting in any way. [0031] Insertion of the prosthetic discs may be approached using modified conventional procedures, such as a posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion (TLIF). In the modified PLIF procedure, the spine is approached via midline incision in the back. The erector spinae muscles are stripped bilaterally from the vertebral lamina at the required levels. A laminectomy is then performed to further allow visualization of the nerve roots. A partial facetectomy may also be performed to facilitate exposure. The nerve roots are retracted to one side and a discectomy is performed. Optionally, a chisel may then used to cut one or more grooves in the vertebral end plates to accept the fixation components on the prostheses. Appropriately-sized prostheses may then be inserted into the intervertebral space on either side of the vertebral canal. [0032] In a modified TLIF procedure, the approach is also posterior, but differs from the PLIF procedure in that an entire facet joint is removed and the access is only on one side of the vertebral body. After the facetectomy, the discectomy is performed. Again, a chisel may be used to create on or more grooves in the vertebral end plates to cooperatively accept the fixation components located on each prosthesis. The prosthetic discs may then be inserted into the intervertebral space. One prosthesis may be moved to the contralateral side of the access and then a second prosthesis then inserted on the access side. [0033] It should be apparent that we refer to these procedures as “modified” in that neither procedure is used to “fuse” the two adjacent vertebrae. [0034] FIG. 1 shows a top, cross section view of a spine ( 100 ), sectioned across an intervertebral disc ( 102 ). This Figure depicts a minimally invasive surgical procedure for implanting a pair of intervertebral discs in an intervertebral region formed by the removal of a natural disc. This minimally invasive surgical implantation method is performed using a posterior approach, rather than the conventional anterior lumbar disc replacement surgery or the modified PLIF and TLIF procedures described above. [0035] In FIG. 1 , two cannulae ( 104 ) are inserted posteriorly, through the skin ( 107 ), to provide access to the spinal column. More particularly, a small incision is made and a pair of access windows created through the lamina ( 106 ) of one of the vertebrae ( 108 ) on each side of the vertebral canal ( 110 ) to access the natural vertebral disc. The spinal cord ( 112 ) and nerve roots are avoided or moved to provide access. Once access is obtained, the two cannulae ( 104 ) are inserted. The cannulae ( 104 ) may be used as access passageways in removing the natural disc with conventional surgical tools. Alternatively, the natural disc may be removed prior to insertion of the cannulae. The cannulae are also used to introduce the prosthetic intervertebral discs ( 114 ) to the intervertebral region. [0036] The described prosthetic discs are of a design and capability that they may be employed at more than one level, i.e., disc location, in the spine. Specifically, several natural discs may be replaced with my discs. As will be described in greater detail below, each such level will be implanted with at least two of my discs. Kits, containing two of my discs for a single disc replacement or four of my discs for replacement of discs at two levels in the spine, perhaps with sterile packaging are contemplated. Such kits may also contain one or more cannulae having a central opening allowing passage and implantation of my discs. [0037] Once the natural disc has been removed and the cannulae ( 104 ) located in place, a pair of prosthetic discs ( 114 ) is implanted between adjacent vertebral bodies. The prosthetic discs have a shape and size suitable making them suitable for use with (or adapted for) various minimally invasive procedures. The discs may have a shape such as the elongated one-piece prosthetic discs described below. [0038] A prosthetic disc ( 114 ) is guided through each of the cannula such that each of the prosthetic discs ( 114 ) is implanted between the two adjacent vertebral bodies. The two prosthetic discs ( 114 ) may be located side-by-side and spaced slightly apart, as viewed from above. Optionally, prior to implantation, grooves may be formed on the internal surfaces of one or both of the vertebral bodies in order to engage anchoring components or features located on or integral with the prosthetic discs ( 114 ). The grooves may be formed using a chisel tool adapted for use with the minimally invasive procedure, i.e., adapted to extend through a relatively small access space (such as the tunnel-like opening found in through the cannulae) and to chisel the noted grooves within the intervertebral space present after removal of the natural disc. [0039] These discs may be used as shown in FIG. 1 or, optionally, they may be implanted with an additional prosthetic disc or discs, perhaps in the position shown for auxiliary disc ( 116 ). [0040] Additional prosthetic discs may also be implanted in order to obtain desired performance characteristics, and the implanted discs may be implanted in a variety of different relative orientations within the intervertebral space. In addition, the multiple prosthetic discs may each have different performance characteristics. For example, a prosthetic disc to be implanted in the central portion of the intervertebral space may be configured to be more resistant to compression than one or more prosthetic discs that are implanted nearer the outer edge of the intervertebral space. For instance, the stiffness of the outer discs (e.g., 114 ) may each be configured such that those outer discs exhibit approximately 5% to 80% of the stiffness of the central disc ( 116 ), perhaps in the range of about 30% to 60% of the central disc ( 116 ) stiffness. Other performance characteristics may be varied as well. [0041] This description may describe a number of variations of prosthetic intervertebral discs. By “prosthetic intervertebral disc” is meant an artificial or manmade device that is so configured or shaped that it may be employed as a total or partial replacement of an intervertebral disc in the spine of a vertebrate organism, e.g., a mammal, such as a human. The described prosthetic intervertebral discs have dimensions that permit them, either alone or in combination with one or more other prosthetic discs, to substantially occupy the space between two adjacent vertebral bodies that is present when the naturally occurring disc between the two adjacent bodies is removed, i.e., a void disc space. By “substantially occupy” is meant that, in the aggregate, the discs occupy at least about 30% by surface area, perhaps at least about 80% by surface area or more. The subject discs may have a roughly bullet or lozenge shaped structure adapted to facilitate implantation by minimally invasive surgical procedures. [0042] The discs may include both an upper (or top) and lower (or bottom) end plate, where the upper and lower end plates are separated from each other by a compressible element such as one or more core members, where the combination structure of the end plates and compressible element provides a prosthetic disc that functionally approaches or closely mimics a natural disc. The top and bottom end plates may be held together by at least one fiber attached to or wound around at least one portion of each of the top and bottom end plates. As such, the two end plates (or planar substrates) are held to each other by one or more fibers that are attached to or wrapped around at least one domain, portion, or area of the upper end plate and lower end plate such that the plates are joined to each other. [0043] FIG. 2 shows a variation of my prosthetic intervertebral disc ( 200 ). This variation comprises an upper end plate ( 202 ) and a lower end plate ( 204 ) separated by a compressible core assembly ( 206 ). As discussed below in more detail, the compressible core assembly ( 206 ) may be bounded by one or more fibers ( 207 ) extending between the upper end of the compressible core assembly ( 206 ) and the lower end of the compressible core assembly ( 206 ). The compressible core assembly ( 206 ) includes first and second (upper and lower) members comprising first and second threaded sections ( 208 , 210 ) that mate with and turn in matching threads in the upper end plate ( 202 ) and in the lower end plate ( 204 ). The compressible core assembly ( 206 ) may include apertures ( 210 in FIG. 4B ), through which the fibers ( 207 ) may pass. Other components (woven or nonwoven fabrics, wires, etc.) may be used in functional substitution for the fibers ( 207 ). [0044] FIG. 3 is a side view, cutaway view of the end plates ( 202 , 204 ) used in the FIG. 2 device ( 200 ). The threaded regions ( 212 ) may be clearly seen. [0045] FIG. 4A shows the complementary compressible core assembly ( 206 ) with threaded portions. The fibers ( 207 ) may also be seen. FIG. 4B is a top view of the FIG. 4A compressible core assembly ( 206 ) showing apertures ( 210 ) through which the fibers ( 207 ) pass. This variation of the compressible core assembly ( 206 ) is raised from its low profile place in the end plates by twisting the body of the compressible core assembly ( 206 ). [0046] As may be apparent, the oppositely positioned threaded regions must have opposite “handedness” for operation of my device. Said another way: one threaded region must have left handed threads, the other threaded region must have right handed threads. [0047] FIG. 5 shows a side view of another variation of the compressible core assembly ( 220 ) having first and second members ( 221 , 225 ) comprising threaded areas ( 222 , 223 ) that screw into the female threaded areas in upper and lower end plates ( 202 , 204 ). In this variation of the compressible core assembly ( 206 ) the first and second members ( 221 , 225 ) further include a circumferential ring ( 224 ) having a series of openings ( 226 ) that mesh with tools, e.g., tang wrenches, fitting those openings to allow rotation of the compressible core assembly ( 206 ) and raise it from its low profile position. [0048] FIG. 6 shows another variation of first and second end plates ( 230 , 232 ) with having a much smaller threaded area ( 234 ). FIG. 7 shows a side view of a compressible core assembly ( 236 ) with smaller threaded posts ( 238 ) and a circumferential ring ( 240 ) with openings ( 242 ) for rotation of the compressible core assembly ( 206 ). [0049] FIG. 8 shows, in cross section, another variation of the end plates, in this case configured to cooperatively engage the core assembly ( 260 ) shown in FIG. 9 . Specifically, in FIG. 8 , the upper or first end plate ( 250 ) includes a threaded area ( 254 ) in an opening that passes from one face of the end plate ( 250 ) to the other. Lower or second end plate ( 252 ) includes a closed-end, thread-free cavity ( 256 ) configured to allow the stub ( 258 ) on the lower end of compressible core assembly ( 260 ) as seen in FIG. 9 to rotate therein during implantation of the disc assembly. A passageway ( 262 ) at least partially through the lower end plate ( 252 ) and cavity ( 256 ) may be used to accommodate a through-pin that, by also passing through a passageway ( 264 ) in stub ( 258 ), secures the core assembly ( 260 ) to second end plate ( 252 ). Such a pin would be installed after the core assembly ( 260 ) is finally positioned with regard to the first end plate ( 250 ) and second end plate ( 252 ) during implantation of the disc assembly. [0050] FIG. 9 shows a side view of a compressible core assembly ( 260 ) having a first core member comprising a threaded post ( 266 ), a second core member ( 258 ) comprising a smooth post ( 258 ), and circumferential rings or plates ( 268 ) with openings ( 270 ) for rotation of the compressible core assembly ( 260 ). The smooth post ( 258 ) may include an opening ( 264 ) for the pin noted above. [0051] FIG. 10 shows a variation in which the depicted end plates may be used with the core assembly shown in FIG. 11 . [0052] FIG. 10 shows a first end plate ( 272 ) includes a threaded stub or post ( 276 ) and a second end plate ( 274 ) having a cavity ( 278 ). The cavity ( 278 ) allows rotation of post ( 282 ) associated with core assembly ( 284 in FIG. 11 ) during the implantation step. A passageway ( 280 ) in second end plate ( 274 ) corresponding to the passageway ( 290 ) may be used to immobilize the core assembly ( 284 ) with respect to the second end plate ( 274 ) by inserting a pin through both. [0053] FIG. 10 shows second end plate ( 274 ) having a cavity ( 278 ) with a smooth wall. [0054] FIG. 11 shows a side view of the compressible core assembly ( 284 ) having a first core member ( 285 ) with a set of circumferentially located openings ( 286 ) for rotation of the compressible core assembly ( 284 ). The first core member ( 284 ) also includes a threaded passageway ( 288 ), that mates with the threaded post ( 276 ) associated with first end plate ( 272 ), so that when they are rotated with respect to each other in a specific direction, the first end plate ( 272 ) moves away from the second end plate ( 274 ). [0055] As noted elsewhere, the shape of my prosthetic intervertebral disc may be oblong, round, kidney shaped, or other convenient shape. The core assemblies exemplified above are conveniently round to allow ease of installation, by rotating the core member. Rotating the core member from the edge in the prepared narrow intervertebral space, as must be done with the device described here, is easiest if the upper member and the lower member are circular. Non-circular core members may be rotated, of course, but typically with a greater level of difficulty. Posterior introduction of prosthetic discs into the spine may require solution of a number of geometric considerations. For instance, the device shown in FIG. 2 has is quite narrow with respect to its width. Depending upon the design of the prosthetic disc, it may de desirable to utilize a non-circular core member. For the device shown in FIG. 2 , for instance, the core member might be narrow and long. Rotating such a core member in the intervertebral space might even be impossible. The variation described below is an example of my prosthetic disc, but in which the core member does not rotate in expanding the disc to the desired size. [0056] FIGS. 12A-12C show a partial cross-section, end view of a prosthetic disc ( 300 ) in which the compressible core assembly ( 318 ) remains relatively stationary as the disc is axially expanded, i.e., the distance between the end plates is increased, by rotating one or more rotatable members. [0057] In particular, FIG. 12A shows in partial cross-section, side view, a first end plate ( 304 ) and a second end plate ( 306 ). A first threaded post ( 308 ) is screwed into a threaded passageway in first end plate ( 304 ) and a second threaded post ( 310 ) is screwed into a threaded passageway in second end plate ( 306 ). The threaded posts ( 308 , 311 ) form a portion or subcomponent, respectively, of the first rotatable member ( 310 ) and of the second rotatable member ( 312 ). In the variation shown in FIGS. 12A-12C , both the first rotatable member ( 310 ) and second rotatable member ( 312 ) are rotatable with respect to the central compressible core assembly ( 302 ). The central compressible core assembly ( 302 ), in turn, is comprised of first core component ( 314 ), second core component ( 316 ), and a resilient core ( 318 )—here shown with at least one fiber passing between and connecting first core component ( 314 ) and second core component ( 316 ). The first core component ( 314 ) and second core component ( 316 ) may be substantially flat, having openings for the noted fiber, and provide for axial retention of, and rotatability of the first rotatable member ( 310 ) and of the second rotatable member ( 312 ). First rotatable member ( 310 ) and second rotatable member ( 312 ) may have openings ( 313 , 315 ) into which tools for preventing the twisting of the central compressible core assembly ( 302 ) during rotation of the first rotatable member ( 310 ) and of the second rotatable member ( 312 ) using, e.g., wrench openings ( 317 ). [0058] FIG. 12B shows a top view of the device ( 300 ) with the threaded post ( 308 ) and first end plate ( 304 ) in view. The outline of the substantially circular first rotatable member ( 310 ) and the long and thin first core component ( 314 ). [0059] FIG. 12C shows a side-view of the device ( 300 ) with first end plate ( 304 ) and second end plate ( 306 ). Threaded posts ( 308 , 311 ) may be seen separating the first rotatable member ( 310 ) and of the second rotatable member ( 312 ), respectively, from the first end plate ( 304 ) and second end plate ( 306 ). The central compressible core assembly ( 302 ) is held in position as the first rotatable member ( 310 ) and of the second rotatable member ( 312 ) are rotated to expand the device ( 300 ). Pins may be inserted into openings ( 320 , 322 ) to prevent the movable portions of the device ( 300 ) from rotating after implantation. [0060] The variously depicted end plates may be planar substrates having a length of from about 12 mm to about 45 mm, such as from about 13 mm to about 44 mm, a width of from about 11 mm to about 28 mm, such as from about 12 mm to about 25 mm, and a thickness of from about 0.5 mm to about 5 mm, such as from about 1 mm to about 3 mm. The top and bottom end plates are fabricated or formed from a physiologically acceptable material that provides for the requisite mechanical properties, primarily structural rigidity and durability. Representative materials from which the end plates may be fabricated are known to those of skill in the art and include: metals such as titanium, titanium alloys, stainless steel, cobalt/chromium, etc.; plastics such as polyethylene with ultra high molar mass (molecular weight) (UHMW-PE), polyether ether ketone (PEEK), etc.; ceramics; graphite; etc. [0061] As mentioned above, the various compressible core assemblies (e.g., 206 , 220 , 236 , 260 , 286 , 306 ) may also include fibers ( 207 ) wound between and connecting the upper and lower ends (e.g., 210 , 222 , 238 ) and (e.g., 208 , 223 , 238 ) having threaded areas. These fibers ( 207 ) may extend through a plurality of openings or apertures ( 211 shown in FIG. 4B ) formed on portions of each of the upper and lower threaded ends. Thus, as an example for each of the variations disclosed here, in the variation shown in FIGS. 4A and 4B , a fiber ( 207 ) extends between the pair of threaded areas ( 208 , 210 ), and extends up through a first aperture ( 211 ) in the upper threaded area ( 210 ) and back down through an adjacent aperture ( 211 ) in the upper threaded area ( 210 ). The fibers ( 207 ) may not be tightly wound, thereby allowing a degree of axial rotation, bending, flexion, and extension by and between the end plates. The amount of axial rotation generally is in the range from about 0° to about 15°, perhaps from about 2° to 10°. The amount of bending generally has a range from about 0° to about 18°, perhaps from about 2° to 15°. The amount of flexion and extension generally has a range from about 0° to about 25°, perhaps from about 3° to 15°. Of course, the fibers ( 207 ) may be more or less tightly wound to vary the resultant values of these rotational values. [0062] The lateral, or horizontal, surface area of each of the end plates ( 202 , 204 )—i.e., the area of the disc surfaces that engage the vertebral bodies—is substantially larger than the cross-sectional surface area of the core member or members. The cross-sectional surface area of the core member or members may be from about 5% to about 80% of the cross-sectional area of a given end plate ( 202 , 204 ), perhaps from about 10% to about 60%, or from about 15% to about 50%. In this way, for a given compressible core ( 206 ) having sufficient compression, flexion, extension, rotation, and other performance characteristics but having a relatively small cross-sectional size, the core member may be used to support end plates having a relatively larger cross-sectional size in order to help prevent subsidence into the vertebral body surfaces. In the variations described here, the compressible core ( 206 ) and end plates ( 202 , 204 ) also have a size that is appropriate for or adapted for implantation by way of posterior access or minimally invasive surgical procedures, such as those described above. [0063] The variations otherwise shown in the Figures may be wound in the same fashion. [0064] FIG. 13 , step (a), shows placement of a low profile disc ( 400 ) into the intervertebral space ( 402 ) between an upper vertebra ( 404 ) and the adjacent lower vertebra ( 406 ). The low profile disc ( 400 ) has been passed through the cannula ( 410 ) to the implantation site. [0065] FIG. 13 , step (b) shows the disc ( 402 ) after the core has been twisted to separate the two end plates and achieve the high profile. The cannula ( 410 ) is being removed. [0066] Many of the described prosthetic discs depicted in the Figures have a greater length than width. The aspect ratio (length:width) of the discs may be about 1.5:1 to 5.0:1, perhaps about 2.0:1 to 4.0:1, or about 2.5: to 3.5:1. Exemplary shapes to provide these relative dimensions include circular, rectangular, oval, bullet-shaped, lozenge-shaped, kidney-shaped and others. These shapes facilitate implantation of the discs by the minimally invasive procedures described above. [0067] The surfaces of the upper and lower end plates, those surfaces in contact with and eventually adherent to the respective opposed bony surfaces of the upper and lower vertebral bodies, may have one or more anchoring or fixation components or mechanism for securing those end plates to the vertebral bodies. For example, the anchoring feature may be one or more “keels,” a fin-like extension often having a substantially triangular cross-section and having a sequence of exterior barbs or serrations. This anchoring component is intended to cooperatively engage a mating groove that is formed on the surface of the vertebral body and to thereby secure the end plate to its respective vertebral body. The serrations enhance the ability of the anchoring feature to engage the vertebral body. [0068] Further, this variation of the anchoring component may include one or more holes, slots, ridges, grooves, indentations, or raised surfaces to further assist in anchoring the disc to the associated vertebra. These physical features will so assist by allowing for bony ingrowth. Each end plate may have a different number of anchoring components, and those anchoring features may have a different orientation on each end plate. The number of anchoring features generally ranges in number from about 0 to about 500, perhaps from about 1 to 10. Alternatively, another fixation or anchoring mechanism may be used, such as ridges, knurled surfaces, serrations, or the like. In some variations, the discs will have no external fixation mechanism. In such variations, the discs are held in place laterally by the friction forces between the disc and the vertebral bodies. [0069] Further, each of the described variations may additionally include a porous covering or layer (e.g., sprayed Ti metal) allowing boney ingrowth and may include some osteogenic materials. [0070] As noted above, in the variations shown herein, the upper and lower threaded portions of the compressible core assembly may each contain a plurality of apertures through which the fibers may be passed through or wound, as shown. The actual number of apertures contained on a threaded portion is variable. Increasing the number of apertures allows an increase in the circumferential density of the fibers holding the threaded portions together. The number of apertures may range from about 3 to 100, perhaps in the range of 10 to 30. In addition, the shape of the apertures may be selected so as to provide a variable width along the length of the aperture. For example, the width of the apertures may taper from a wider inner end to a narrow outer end, or visa versa. Additionally, the fibers may be wound multiple times within the same aperture, thereby increasing the radial density of the fibers. In each case, this improves the wear resistance and increases the torsional and flexural stiffness of the prosthetic disc, thereby further approximating natural disc stiffness. In addition, the fibers may be passed through or wound on each aperture, or only on selected apertures, as needed. The fibers may be wound in a uni-directional manner, where the fibers are wound in the same direction, e.g., clockwise, which closely mimics natural annular fibers found in a natural disc, or the fibers may be wound bi-directionally. Other winding patterns, both single and multi-directional, may also be used. [0071] The apertures provided in the various threaded portions discussed here, may be of a number of shapes. Such aperture shapes include slots with constant width, slots with varying width, openings that are substantially round, oval, square, rectangular, etc. Elongated apertures may be radially situated, circumferentially situated, spirally located, or combinations of these shapes. More than one shape may be utilized in a single end plate. [0072] One purpose of the fibers is to hold the upper and lower threaded portions together and to limit the range-of-motion to mimic or at least to approach the range-of-motion of a natural disc. The fibers may comprise high tenacity fibers having a high modulus of elasticity, for example, at least about 100 MPa, perhaps at least about 500 MPa. By high tenacity fibers is meant fibers able to withstand a longitudinal stress of at least 50 MPa, and perhaps at least 250 MPa, without tearing. The fibers ( 207 ) are generally elongate fibers having a diameter that ranges from about 100 μm to about 1000 μm, and preferably about 200 μm to about 400 μm. The fibrous components may be single strands or, more typically, multi-strand assemblages. Optionally, the fibers may be injection molded or otherwise coated with an elastomer to encapsulate the fibers, thereby providing protection from tissue ingrowth and improving torsional and flexural stiffness. The fibers may be coated with one or more other materials to improve fiber stiffness and wear. Additionally, the core may be injected with a wetting agent such as saline to wet the fibers and facilitate the mimicking of the viscoelastic properties of a natural disc. The fibers may comprise a single or multiple component fibers. [0073] The fibers may be fabricated from any suitable material. Examples of suitable materials include polyesters (e.g., Dacron® or the Nylons), polyolefins such as polyethylene, polypropylene, low-density and high density polyethylenes, linear low-density polyethylene, polybutene, and mixtures and alloys of these polymers. HDPE and UHMWPE are especially suitable. Also suitable are various polyaramids, poly-paraphenylene terephthalamide (e.g., Kevlar®), carbon or glass fibers, various stainless steels and superelastic alloys (such as nitinol), polyethylene terephthalate (PET), acrylic polymers, methacrylic polymers, polyurethanes, polyureas, other polyolefins (such as polypropylene and other blends and olefinic copolymers), halogenated polyolefins, polysaccharides, vinylic polymers, polyphosphazene, polysiloxanes, liquid crystal polymers (LCP) such as those available under the tradename VECTRA, polyfluorocarbons such as polytetrafluoroethylene and e-PTFE, and the like. [0074] The fibers may be terminated on an end plate in a variety of ways. For instance, the fiber may be terminated by tying a knot in the fiber on the superior or inferior surface of an end plate. Alternatively, the fibers may be terminated on an end plate by slipping the terminal end of the fiber into an aperture on an edge of an end plate, similar to the manner in which thread is retained on a thread spool. The aperture may hold the fiber with a crimp of the aperture structure itself, or by an additional retainer such as a ferrule crimp. As a further alternative, tab-like crimps may be machined into or welded onto the threaded portion structure to secure the terminal end of the fiber. The fiber may then be closed within the crimp to secure it. As a still further alternative, a polymer may be used to secure the fiber to the threaded portions by welding, including adhesives or thermal bonding. That terminating polymer may be of the same material as the fiber (e.g., UHMWPE, PE, PET, or the other materials listed above). Still further, the fiber may be retained on the threaded portions by crimping a cross-member to the fiber creating a T-joint, or by crimping a ball to the fiber to create a ball joint. [0075] The core members provide support to and maintain the relative spacing between the upper and lower end plates. The core members may comprise one or more relatively compliant materials. In particular, the compressible core members in this variation and the others discussed herein, may comprise a thermoplastic elastomer (TPE) such as a polycarbonate-urethane TPE having, e.g., a Shore value of 50 D to 60 D, e.g. 55 D. An example of such a material is the commercially available TPE, BIONATE. Shore hardness is often used to specify flexibility or flexural modulus for elastomers. [0076] We have had success with core members comprising TPE that are compression molded at a moderate temperature from an extruded plug of the material. For instance, with the polycarbonate-urethane TPE mentioned above, a selected amount of the polymer is introduced into a closed mold upon which a substantial pressure may be applied, while heat is applied. The TPE amount is selected to produce a compression member having a specific height. The pressure is applied for 8-15 hours at a temperature of 70°-90° C., typically about 12 hours at 80° C. [0077] Other examples of suitable representative elastomeric materials include silicone, polyurethanes, or polyester (e.g., Hytrel®). [0078] Compliant polyurethane elastomers are discussed generally in, M. Szycher, J. Biomater. Appl. “Biostability of polyurethane elastomers: a critical review”, 3(2):297 402 (1988); A. Coury, et al., “Factors and interactions affecting the performance of polyurethane elastomers in medical devices”, J. Biomater. Appl. 3(2):130 179 (1988); and Pavlova M, et al., “Biocompatible and biodegradable polyurethane polymers”, Biomaterials 14(13):1024 1029 (1993). Examples of suitable polyurethane elastomers include aliphatic polyurethanes, segmented polyurethanes, hydrophilic polyurethanes, polyether-urethane, polycarbonate-urethane, and silicone-polyether-urethane. [0079] Other suitable elastomers include various polysiloxanes (or silicones), copolymers of silicone and polyurethane, polyolefins, thermoplastic elastomers (TPE's) such as atactic polypropylene, block copolymers of styrene and butadiene (e.g., SBS rubbers), polyisobutylene, and polyisoprene, neoprene, polynitriles, artificial rubbers such as produced from copolymers produced of 1-hexene and 5-methyl-1,4-hexadiene. [0080] One variant of the construction for the core member comprises a nucleus formed of a hydrogel and an elastomer reinforced fiber annulus. [0081] For example, the nucleus, the central portion of the core member, may comprise a hydrogel material. Hydrogels are water-swellable or water-swollen polymeric materials typically having structures defined either by a crosslinked or an interpenetrating network of hydrophilic homopolymers or copolymers. In the case of physical crosslinking, the linkages may take the form of entanglements, crystallites, or hydrogen-bonded structures to provide structure and physical integrity to the polymeric network. [0082] Suitable hydrogels may be formulated from a variety of hydrophilic polymers and copolymers including polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyethylene oxide, polyacrylamide, polyurethane, polyethylene oxide-based polyurethane, and polyhydroxyethyl methacrylate, and copolymers and mixtures of the foregoing. [0083] Silicone-base hydrogels are also suitable. Silicone hydrogels may be prepared by polymerizing a mixture of monomers including at least one silicone-containing monomer and or oligomer and at least one hydrophilic co-monomer such as N-vinyl pyrrolidone (NVP), N-vinylacetamide, N-vinyl-N-methyl acetamide, N-vinyl-N-ethyl acetamide, N-vinylformamide, N-vinyl-N-ethyl formamide, N-vinylformamide, 2 -hydroxyethyl-vinyl carbonate, and 2-hydroxyethyl-vinyl carbamate (beta-alanine). [0084] The annulus may comprise an elastomer, such as those discussed just above, reinforced with a fiber. [0085] The fiber may be wrapped around the core member in a variety of different configurations, e.g., wrapping the core member in a random pattern, circumferential wrapping, radial wrapping, progressive polar (or near-polar) wrapping moving around the core, and combinations of these patterns and with other patterns. [0086] The shape of each of the core members may be cylindrical, although the shape (as well as the materials making up the core member and the core member size) may be varied to obtain desired physical or performance properties. For example, the core member's shape, size, and materials will directly affect the degree of flexion, extension, lateral bending, and axial rotation of the prosthetic disc. [0087] Where a range of values is provided, it is understood that each intervening value within the range, to the tenth of the unit of the lower limit (unless the context clearly dictates otherwise), between the upper and lower limit of that range and any other stated or intervening value in that stated range is described. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges is also described, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also described. [0088] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the medical devices art. Although methods and materials similar or equivalent to those described here may also be used in the practice or testing of the described devices and methods, the preferred methods and materials are described in this document. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. [0089] It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. [0090] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual variations described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of this disclosure. For example, and without limitation, several of the variations described here include descriptions of anchoring features, protective capsules, fiber windings, and protective covers covering exposed fibers for integrated end plates. It is expressly contemplated that these features may be incorporated (or not) into those variations in which they are not shown or described. [0091] All patents, patent applications, and other publications mentioned herein are hereby incorporated herein by reference in their entireties. The patents, applications, and publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that contents of those patents, applications, and publications are “prior” as that term is used in the Patent Law. [0092] The preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles otherwise described here and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the described principles of my devices and methods. Moreover, all statements herein reciting principles, aspects, and variation as well as specific examples thereof, are intended to encompass both structural and functional equivalents. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.	The described devices are spinal implants that may be surgically implanted into the spine to replace damaged or diseased discs using a posterior approach. The discs are prosthetic devices that approach or mimic the physiological motion and reaction of the natural disc.	0
This application is a conversion from and claims benefit of a provisional application 61/195,499, filed on Oct. 7, 2008. BACKGROUND OF THE INVENTION The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. The invention is related in general to equipment for servicing subterranean wells. The invention relates to a deepsea cement head that is intended to drop a combination of darts, balls, bombs and canisters in order to activate downhole equipment, launch cementing plugs, deliver chemical products, or the like. Existing tools implement a modular design with darts that are preloaded in baskets within the modules. The modules are connected to one another using clamps. The darts are held in place mechanically and released by removing the mechanical obstruction and redirecting the flow of the pumped fluid through the dart basket. The darts are then pumped through the tool by the fluid. The first dart to be launched is placed in the lowest module, with subsequent darts passing through the baskets vacated by the earlier darts. Darts in prior designs are launched by blocking the bypass flow of the process fluid and forcing the fluid through the dart chamber. The dart forms an initial seal when placed into the basket. When fluid enters the dart chamber, pressure builds and breaks the seal, forcing the dart out of the basket, through the tool and into the main process-fluid stream. Some prior art designs consist of modules similar to those described in U.S. Pat. Nos. 4,624,312 and 4,890,357. The darts are loaded from the topmost module, through the swivel if necessary, and pushed down to their respective baskets with a long rod. The modules have valves that are used to select between the dart and the bypass flow. The valve itself serves as the mechanical obstruction that prevents the dart from prematurely launching. When the valve is turned, it simultaneously opens a passage for the dart while closing the passage of the bypass flow. It remains desirable to provide improvements in wellsite surface equipment in efficiency, flexibility, and reliability. SUMMARY OF THE INVENTION The present invention allows such improvement. In a first aspect, the present invention relates to a multiple activation-device launching system for a cementing head, comprising a launcher body comprising at least one launching chamber, the launching chamber sized to receive one or more activation devices therein, the launching chamber in fluid communication with a power source for launching the activation device into the principal process-fluid stream. In another aspect, the present invention aims at a method for deploying one or more activation devices into a process-fluid system into a process-fluid system utilizing an angled launching system for a cementing head comprising a launcher body comprising a primary valve and at least one launching chamber, the launching chamber equipped with a secondary valve and sized to receive one or more activation devices therein, the launching chamber in fluid communication with a power source for launching one or more activation devices into the principal process-fluid stream. In a further aspect, the present invention pertains to a method for deploying one or more activation devices into a process-fluid system utilizing an angled launching system for a cementing head comprising a launcher body comprising at least one launching chamber and a device chamber, the launching chamber sized to receive one or more activation devices therein, the launching chamber in fluid communication with an external power source for launching one or more activation devices into the principal process-fluid stream. An embodiment of the invention comprises a single activation-device launcher module that contains multiple launching chambers arranged at an angle relative to the main axis of the tool. The activation devices may be darts, balls, bombs or canisters. The devices are loaded into their respective chambers directly or in a cartridge, but directly from the open air rather than through the length of the tool. A variety of methods can be used to launch the activation devices. The activation devices may also contain chemical substances that, upon exiting the launching chamber, are released into the well. The advantages of the general implementation of the embodiment is that more activation devices may be fit into a shorter length tool, simplifying the loading process, and making the baskets more accessible for maintenance purposes. This allows to easily maintaining the tool on the rig when the system from the art can only be serviced at the district. In another embodiment of the invention, the system may comprise any number of launching chambers (at least one, but preferably two, three, four or more), each with an axis at an angle relative to the main axis of the tool. The chamber(s) may be positioned at the same level, or a different level (e.g. in spiral, or stages). When the activation devices are forced out of the chamber(s), they enter the main body of the tool in the correct orientation and are swept away by the pumped fluid (hereafter called process fluid) to serve their intended purpose. The exact number of chambers is not essential, indeed, multiple unique launching methods that will work independently from the arrangement of the launching chambers are contemplated. In a preferred embodiment, the activation devices are launched with process-fluid power as the motive power. Each launching chamber is preferably linked to the main flow of process fluid using a small pipe, hose, or integral manifold. A valve (primary valve) blocks the main flow on command, diverting the fluid into the launching chambers. Each launching chamber would comprise a valve (secondary valve) that alternately allows or blocks the flow of fluid into the corresponding launching chamber. All valves may be manually or remotely actuated. In a launch procedure, all secondary valves are initially closed, the primary valve is initially open. To launch an activation device, the operator opens the secondary valve corresponding to the activation device's chamber and then closes the primary valve. Once the activation device is successfully ejected from the launching chamber, the primary valve is reopened and the launch procedure is repeated for launching additional activation devices. In another embodiment, external fluid power is used to launch the activation devices from their chambers. The external fluid power employed to force the activation device from its chamber may comprise water or fluid connected directly behind the activation device; a hydraulic cylinder with a rod that forces the dart out of its chamber, a hydraulic piston without a rod that seals within the launching chamber (activation device on one side, external fluid on the other), a bladder behind the activation device that fills from an external fluid source pushing the activation device out of the chamber, or a similar type of fluid power as will be appreciated by those skilled in the art. Although the disclosed launching system is mainly being presented in the context of well cementing, it will be appreciated that the process-fluid stream could comprise other well fluids including, but not limited to, drilling fluids, cement slurries, spacer fluids, chemical washes, acidizing fluids, gravel-packing fluids and scale-removal fluids. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1D are conceptual views of a multiple activation-device launcher that employs valves to divert process-fluid flow to the launching chamber, forcing an activation device to exit the launching chamber. FIGS. 1A-1D depict a dart, a ball, a canister and a bomb, respectively, occupying the launching chamber. FIG. 2 is a conceptual view of a multiple activation-device launcher featuring an external power source that, when energized, forces the activation device to exit the launching chamber. FIG. 3 is a conceptual view of a multiple activation-device launcher employing a fluid as the external power source. FIG. 4 is a conceptual view of a multiple activation-device launcher employing a piston as the external power source. FIG. 5 is a conceptual view of a multiple activation-device launcher employing an inflatable bladder as the external power source. FIG. 6 is a conceptual view of a multiple activation-device launcher employing a rod and piston as the external power source. FIG. 7 is an external view of the invention featuring multiple launching chambers. DETAILED DESCRIPTION According to a preferred embodiment, the invention involves the diversion of process-fluid flow from the principal flow stream through the launcher body to one of the launching chambers. Referring to FIGS. 1A-1D , the launcher module comprises two principal elements—the launcher body 1 which is the primary conduit through which the process fluid flows; and one or more launching chambers 2 containing one or more activation devices 7 and connected to the primary conduit. Activation devices are launched by closing the primary valve 5 , which diverts process-fluid flow from the principal flow direction 3 into the conduit 4 connecting the main body to the launching chambers. Each launching chamber shall be equipped with a secondary valve 6 that allows or blocks process-fluid flow into the chamber. When the secondary valve is opened, and process fluid flows into the launching chamber, the activation device is pushed out of the launching chamber and into the principal process-fluid stream. The activation device 7 may be a dart ( FIG. 1A ), a ball ( FIG. 1B ), a canister ( FIG. 1C ) or a bomb ( FIG. 1D ). The primary valve preferably needs only to withstand enough differential pressure to force the activation device from the launching chamber. The primary valve may be a plug valve, a butterfly valve, a balloon-shaped bladder that inflates from the center to seal the main fluid passage, a doughnut-shaped bladder that inflates from the edges to seal the main fluid passage, a pressure-operated rubber component similar to those used in BOPs or inflatable packers or similar type valve, as will be appreciated by those skilled in the art. The secondary valves may be any variety of on-off valves, but are preferably designed to be easily removed and cleaned after repeated exposure to particle-laden fluids such as cement slurry. The secondary valve may be a plug valve, a butterfly valve, a balloon-shaped bladder that inflates from the center to seal the main fluid passage, a doughnut-shaped bladder that inflates from the edges to seal the main fluid passage, a pressure-operated rubber component similar to those used in BOPs or inflatable packers, or similar type valve as will be appreciated by those skilled in the art. In another embodiment, shown in FIG. 2 , an external device 8 forces the one or more activation devices from the launching chamber 7 . Several types of external power are envisioned. As shown in FIG. 3 , water or fluid connected directly behind the activation device may be used to expel the device from its chamber. The fluid is not directly connected to the main process fluid. A hydraulic line 9 conveys the fluid to the launching chamber 2 . The operator opens a one-way valve 10 , allowing the fluid to flow into the launching chamber and carry the activation device 7 out of the launching chamber and into the main process-fluid flow. As shown in FIG. 4 , a hydraulic line 9 conveys fluid to the launching chamber 2 . After the operator actuates the one-way valve 10 , the fluid enters the launching chamber and forces a piston 11 to move and push the activation device 7 out of the launching chamber and into the main process-fluid flow. As shown in FIG. 5 , a hydraulic line 9 conveys fluid to the launching chamber 2 . After the operator actuates the one-way valve 10 , the fluid enters the launching chamber and inflates a bladder 12 . As the bladder inflates, it pushes the activation device 7 out of the launching chamber and into the main process-fluid flow. As shown in FIG. 6 , a hydraulic rod 13 extends out of the upper portion of the launching chamber 2 , and is connected to a piston 14 inside the launching chamber. A hydraulic seal 15 isolates the inner and outer portions of the launching chamber. The operator pushes the rod further into the launching chamber, causing the piston to force the activation device 7 out of the launching chamber and into the main process-fluid flow. FIG. 7 is an external view of the present invention with multiple launching chambers. The activation device depicted in FIGS. 2-7 is a dart; however, as shown in FIGS. 1A-1D , activation devices may also include balls, bombs and canisters. The activation devices may be filled with a chemical substance that, upon release from the launching chamber, is dispensed from the activation device into the process fluid. The chemical release may occur at any time after the activation device is launched-from the moment of launching to any time thereafter. Delayed chemical release may be performed for a number of reasons including, but not limited to, avoiding fluid rheological problems that the chemical would cause if added during initial fluid mixing at surface, and triggering the initiation of chemical reactions in the fluid (e.g., cement-slurry setting and fracturing-fluid crosslinking) at strategic locations in the well. The process fluid may comprise one or more fluids employed in well-service operations. Such fluids include, but are not limited to, drilling fluids, cement slurries, spacer fluids, chemical washes, acidizing fluids, gravel-packing fluids and scale-removal fluids. The present invention also comprises a method of operating the multiple activation-device launcher depicted in FIG. 1 comprising inserting one or more activation devices 7 in at least one of the launching chambers 2 , and closing the secondary valves 6 in each of the launching chambers. Process fluid is then pumped through the launcher body 1 . When it is time to release an activation device 7 , the primary valve 5 is closed and the secondary valve 6 is opened in the launching chamber of choice. This diverts process-fluid flow through the launching chamber 2 , forcing the activation device 7 to exit into the launcher body 1 . After the activation device 7 is launched, the secondary valve 6 is closed, the primary valve 5 is reopened to restore process-fluid flow through the launcher body 1 , and the activation device 7 is carried to its destination. This process is then repeated until a sufficient number of activation devices have been deployed to complete the treatment. One or more activation devices may contain a chemical substance that is released to the process fluid after deployment into the process fluid. In another embodiment, the present invention pertains to a method of operating the multiple activation-device launcher depicted in FIG. 2 comprising inserting one or more activation devices 7 in at least one of the launching chambers 2 , and connecting the chambers to an external power source 8 . Power sources include, but are not limited to, a fluid connected directly behind the activation device 7 ( FIG. 3 ), a hydraulic cylinder 14 with a rod 13 ( FIG. 6 ), a hydraulic piston 11 without a rod ( FIG. 4 ), and an inflatable bladder 12 ( FIG. 5 ). Process fluid is pumped through the launcher body 1 . When it is time to release an activation device 7 , the external power source 8 is activated, forcing the activation device 7 to exit into the launcher body 1 . This process is then repeated until a sufficient number of activation devices have been deployed to complete the treatment. One or more activation devices may contain a chemical substance that is released to the process fluid after deployment into the process fluid. The methods of operating the multiple activation-device launcher depicted in FIGS. 1 and 2 may further comprise activation devices containing a chemical substance that is released after the activation device exits the launching chamber. The activation device may begin dispensing the chemical substance immediately upon launching, or at any time thereafter. In the methods of operating the multiple activation-device launcher depicted in FIGS. 1 and 2 , the process fluid may comprise one or more fluids employed in well-service operations. Such fluids include, but are not limited to, drilling fluids, cement slurries, spacer fluids, chemical washes, acidizing fluids, gravel-packing fluids, scale-removal fluids. In addition, the activation devices may comprise darts, balls, bombs and canisters. The preceding description has been presented with reference to presently preferred embodiments of the invention. Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, and scope of this invention. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.	A multiple activation-device launching system for a cementing head comprises a launcher body and at least one launching chamber that are sized to receive one or more activation devices therein. The activation devices are launched into the principal process-fluid stream inside the cementing head, and may be darts, balls, bombs, canisters and combinations thereof. The launching chambers are in fluid communication with an external power source for launching the activation device into the principal process-fluid stream.	4
BACKGROUND OF THE INVENTION This invention relates generally to apparatus for producing a scent within a designated area and, more particularly, pertains to apparatus for introducing desired scents into the air entering an area. In many instances, it is highly desirable to introduce a pleasing scent throughout an entire enclosure such as a house or the like. For example, the cooking of various foods cause unwanted odors to permeate throughout the house and annoy the occupants. Other times, an odor referred to as "house odor" may arise if the house is sealed for a period of time. Alternatively, an occupant may simply desire that a fresh scent permeate the house in view of his particular feelings at that time. In the past, scents have usually been introduced on a per unit basis (i.e., on a room-to-room basis) by uncovering a container having a scent producing liquid therein and placing a wick into the liquid. This is obviously an extremely inefficient way of introducing a scent into the area since it is dependent upon air flow and the rate of evaporation. Additionally, the range of the device is extremely limited. Other techniques for introducing an airborne scent include the use of spray canisters that the occupant operates by depressing a valve button to permit the fluid carrying the scent to escape. This is a more efficient manner than the former method for quickly introducing a scent into the environment but suffers from the drawbacks that it is extremely expensive and the scent only lasts a relatively short period of time. Accordingly, an object of the present invention is to provide improved scent producing apparatus. A more specific object of the invention is to provide scent producing apparatus that quickly and easily introduces a scent throughout an entire enclosure such as a house. Another object of the invention is the provision of scent producing apparatus that is relatively inexpensive to fabricate. A further object of the invention is to provide scent producing apparatus wherein respective different scents may be introduced into an enclosure in a simple and effective manner. Another object of the invention resides in the novel details of construction that provide a scent producing apparatus that is compatible for use with existing forced air heating or cooling systems. SUMMARY OF THE INVENTION Accordingly, apparatus for introducing a scent into a forced air system is provided for use in conjunction with a temperature changing system of the type having a blower and an air filter positioned upstream of the blower. The apparatus comprises a container for retaining a fluid having a desired scent. Spray means is adapted to be connected to the system adjacent the filter whereby fluid exiting through the spray means is sprayed on to the filter. A conduit connects the container with the spray means to provide a passage for the flow of the fluid from the container to the spray means. Additionally, control means is serially connected in the conduit between the container and the spray means and is operable to control the flow of fluid to the spray means thereby to control the scent in the air flowing through the filter. BRIEF DESCRIPTION OF THE DRAWING Other features and advantages of the present invention will become more apparent from a consideration of the following detailed description when taken in conjunction with the accompanying drawing, in which: FIG. 1 is a perspective view of the container and the control device of the apparatus of the present invention; FIG. 2 is a vertical sectional view of a portion of a furnace illustrating the relationship between the apparatus of the present invention and the blower arrangement; FIG. 3 is a detailed view illustrating the relationship between the spray of the apparatus of the present invention and the furnace filter; and FIG. 4 is a schematic circuit wiring diagram of the control portion of the apparatus of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Accordingly, apparatus for introducing a scent into a forced air heating or cooling system is designated generally by the reference character 10 in the FIGS. and comprises a cabinet 12 that is adapted to be mounted on a portion of the forced air system. To be more specific, the forced air system, which is conventional, may comprise a furnace 14 having an upper chamber 16 and a lower chamber 18. Burners 20 are received in the upper chamber 16 and are adapted to heat the air flowing past the burners. Since the present invention does not reside in the burners per se, the burners are not shown in detail. A duct (not shown) connects the upper chamber 16 with registers and the like which control the flow of air from the upper chamber to the various rooms of a house, for example. Positioned within the lower chamber 18 is a blower 22. The blowers are usually of the squirrel cage type and are operated by a motor 24 (FIG. 4) which rotates a fan 26. The fan or impeller 26 forces the air within the lower chamber through a conduit which connects with the upper chamber 16 and distributes the air so that the air flows past the burners 20. (As used herein, the term "blower" includes both the impeller and the motor.) An air return duct 30 provides a path for the flow of air from the rooms in the house to the lower chamber of the furnace 14. To be more specific, an opening 32 is provided in the lower portion of the air return duct and communicates with the lower chamber 18. A bracket 34 is positioned adjacent the opening 32 and receives a filter 36 thereon. The filter may comprise fiberglass wool, interwoven metal straps, etc. which are set within a frame that is supported on the brackets. When the furnace is energized, the blower 22 is operated and the impeller 26 begins to rotate. Air is drawn through the return duct 30 and the filter 36 by means of the blower. The blower then blows this air past the burners and through the room ducts to the various rooms of the house. Although the above description related to a forced air heating system, it is to be understood that it is also applicable to a cooling system. In other words, the burners may be replaced by the coil of an air conditioning system so that the air is cooled rather than heated. In practice, as is conventional in systems of the type under consideration, an air conditioning unit is located in the plenum chamber of the furnace 14 so that air from the blower must traverse the coils of the air conditioning system. When the system is set for cooling, the air conditioner is operated and the air which is forced past the coil will be cooled by the air conditioning unit before it is forced into the rooms. On the other hand, when heating is called for, the air conditioning portion of the system is disabled and the burners 20 are ignited so that the system forces hot air into the rooms. In accordance with the present invention, the cabinet 12 is mounted on the return duct 30 by any conventional means such as sheet metal screws or the like. The cabinet is provided with a door 34 that is hingedly connected to the remainder of the cabinet along its rear edge to facilitate opening and closing of the cabinet. Provided within the cabinet are respective vertically spaced shelves 36 and 38. Received on the shelf 36 are respective containers 40A-40C. The containers have removable closures at the tops thereof so that a fluid may be introduced into the respective containers. Each of the fluids associated with a respective container may comprise a fluid that produces a different scent. Each of the containers is connected by a respective tube 42A-42C to an associated pump 44A-44C. Similarly, a short tube 46A-46C connects each one of the pumps to a respective solenoid operated valve 48A-48C. The pumps are supported on the shelf 38 and the valves are supported on the bottom wall of the cabinet. Each one of the valves 48A-48C is connected with a respective flexible conduit or tube 50A-50C that extends through the wider walls of the air return duct 30 and terminates within the lower chamber 18 adjacent the filter 36. When installing the apparatus 10, appropriate holes for the conduits 50A-50C may be made in the two opposed faces of the duct 30 and grommets 52 are placed in each one of the openings or holes. The grommets serve two purposes. In the first place, they protect the conduits 50A-50C from the sharp edges of the sheet metal forming the return duct 30. Additionally, the grommets seal the openings around the conduits to prevent air leaks around the respective conduits. The conduits or tubes 50A-50C extend through an appropriate opening in a bracket 54 (FIGS. 2 and 3) that extends longitudinally within the lower chamber 18. The bracket 54 forms a portion of the apparatus of the present invention and is adapted to be connected to the upper wall of the lower chamber 18 adjacent the filter 36. Depending from the bracket 54 in facing relationship with the filter 36 are respective tubes 56A-56C which are provided with a plurality of through bores on the side of the tube facing the filter. The upper ends of the tubes are connected to the respective conduits 50A-50C. Fluids flowing through the tubes 56A-56C will exit through the through openings and be sprayed upon the filter 36. The tubes effectively, therefore, operate as spray devices which permit the fluids to be sprayed upon the filter. As shown in FIG. 4, the motor 24 that operates the impeller 26 is connected across power lines L 1 and L 2 . As is conventional, power is not applied to the lines L 1 and L 2 until the thermostat switch closes to call for heating or cooling, as the case may be. In other words, assuming that the area is to be heated, a thermostatic switch is located in the room or area. When the temperature begins to drop and reaches the set point of the thermostat, a circuit is closed whereby the burners 20 are energized and power is applied to the leads L 1 and L 2 to energize the motor 24 and cause the blower to blow air past the burners into the area to be heated. As the temperature in the area rises due to hot air, the thermostatic switch opens thereby deenergizing the burners and removing power from leads L 1 and L 2 . Since the circuit connections between the thermostatic switch and the motor are conventional, they are not shown in detail. In accordance with the present invention, a low voltage transformer 25 is provided which has a primary winding 25P connected across the lines L 1 and L 2 . The respective ends of the secondary winding 25S are connected to respective leads 27 and 29. The pump 44A and the associated solenoid operated valve 48A are serially connected between the leads 27 and 29 through a serially connected single-pole single-throw switch 56A. Similarly, the pump 44B and the valve 48B are connected across the leads 27 and 29 through a switch 56B. In a like manner, the pump 44C and the pump 48C are serially connected between the leads 27 and 29 through a serially connected single-pole single-throw switch 56C. In practice the transformer 25 may be a low voltage twelve volt transformer thereby permitting use of miniature valves and pumps. Additionally, the smaller components make for an extremely economical system with low power drain. Although an ac system has been shown herein, it is to be understood that this is for illustrative purposes only and is not to be interpreted as being a limitation of the present invention. That is, a rectifier may be connected in series with the secondary winding 25S and the components may be changed to dc components. For heavy industrial uses, larger pumps and valves may be used which may necessitate use at line voltages. In operation, the respective switches 58A-58C may be located in the same area as the thermostat (i.e., in the living area) for easy accessability. When it is desired to operate the system, the switches 58A-58C are closed depending upon which scent is desired. Assuming that the scents produced by the fluids in all three containers 40A-40C are desired, all three of the switches 58A-58C are closed so that the pumps 44A-44C and the associated valves 48B-48C are connected across the leads 27 and 29. When the thermostatic switch closes to energize the motor 24 by applying power to the leads L 1 and L 2 , each one of the pumps and associated valve will likewise be operated. Thus, when the blower is energized, the valve 48A will open (since the valves are in the normally closed position) and the pump 44A will pump fluid within the container 40A through the valve to the tube 56A. The fluid will exit from the openings in the tube and be sprayed on the filter 36. Similar comments apply with respect to the remainder of the valves and pumps so that fluid will also be sprayed on the filter 36 via the tubes 56B and 56C. Accordingly, the air being drawn through the filter 36 by the blower 22 will pick up the scents from the fluid sprayed on the filter and, as the air is blown through the various duct comprising the air system, the scents will be distributed throughout the house. If less than all of the scents in the containers are desired, the appropriate switches 58A-58C may be opened to disable the associated valve as desired by the operator. Additionally, the fluids within the containers 40A-40C may be changed in accordance with the desires of the operator so that different scents may be interchanged at different times. Accordingly, scent producing apparatus has been disclosed which is easily adapted to be connected with existing forced air systems so that scents may be distributed quickly throughout an area in a minimum period of time. While a preferred embodiment has been shown and disclosed herein, it will become obvious that numerous omissions, changes and additions may be made in such embodiment without departing from the spirit and scope of the present invention. For example, the pumps 40A-40C may be completely eliminated so that the apparatus is of the gravity-fed type. In other words, the fluid would simply pass through the tubes 56A-56C under the influence gravity and pass from the tubes to the filter. Alternatively, the system filter need not be used but some member may be placed in the air system so that the scent carrying fluid can be sprayed on the device.	Apparatus is provided for introducing a scent into a forced air temperature changing system of the type having a blower and an air filter positioned upstream of the blower. The apparatus comprises a container for retaining a fluid having the desired scent. A spray device is positioned adjacent the filter and is connected to the system so that the scent containing fluid exiting through the spray device is sprayed onto the filter. A conduit connects the container with the spray device to provide a passage for the flow of the fluid from the container to the spray device. Control means serially connected in the conduit between the container and the spray device controls the flow of the fluid to the spray device. Hence, by operating the control means, the fluid is selectively sprayed on to the filter. The air flowing through the filter picks up the scent and brings the scent to the desired area.	5
TECHNICAL FIELD [0001] The present invention relates to a permeation device for permeating a wetting agent to fabric, for insulation, waterproofing, antifouling, antibacterial, flame retardant, and other properties, and specifically to a permeation system for permeating a supplied wetting agent to fabric with a rotary permeation paddle device and a method for manufacturing fabrics using the same. BACKGROUND [0002] Generally, clothing has been means for protecting human bodies from external environments and, in modern days, has become means of fashion for expressing oneself to others. Recently, functional clothing having insulation, waterproofing, antifouling, antibacterial, flame retardant, and other advantageous properties, in addition to being means of fashion, is drawing attention. To manufacture such clothing, special processing is performed on fabrics. [0003] As an example, fabric having insulation functionality is permeated with aerogel, which is used as an insulation material due to its very low thermal conductivity. The aerogel has been recognized as a novel material, made of silicon oxide (SiO2), which has drawn attention, since its discovery in the 1930s, as an insulation material, an impact absorbing material, and a soundproofing material, etc. as it is resistant to heat, electricity, sound, and impact, etc., and is only three times as heavy as air of the same volume. Further, aerogel is formed of silicon oxide threads having a diameter of one ten-thousandth of human hair, tangled extremely sparsely, and air molecules occupy the space between threads, and air accounts for 98% of the total volume. [0004] A system and method of processing fabric using aerogel as a wetting agent is disclosed in Korean Patent No. 01255631, which was granted from a patent application filed by the present applicant. In short, the patented system includes a mixture supply part, a non-woven fabric supply roll, an insulation processing and transporting part permeating a mixture into a non-woven fabric using a blade, a drying part, and an insulation padding collecting roll. SUMMARY OF THE INVENTION [0005] However, when using a blade, a mixture is permeated slowly, the permeation takes a long time, and thus a lengthy permeation process is required. Accordingly, the processing time of the overall process is long, which is disadvantageous. [0006] The present invention resolves the above problems, and aims to provide (i) a fabric permeation system by permeating into fabric a wetting agent which provides functionality, using a rotary permeation paddle device, thereby significantly shortening the time spent on permeation process and continuously and quickly performing the permeation process, which shortens the processing time of the overall process, and (ii) a method of manufacturing fabric using the same. [0007] As described above, according to the present invention, a rotary permeation paddle device permeates into fabric the wetting agent transported to the rotary permeation paddle device by evenly spreading the supplied wetting agent with a permeation paddle and uniformly applying it to the fabric, thereby obtaining homogeneous functional fabric. [0008] Also, the described embodiments provide a simplified permeation process with a reduced processing time, which has an effect of increasing the productivity of manufacturing fabric permeated with the wetting agent. BRIEF DESCRIPTION OF DRAWINGS [0009] The accompanying drawings attached to the specification illustrate embodiments of the present invention, which, when viewed in conjunction with the detailed description of the invention, assist better understanding of the technical aspects of the present invention. However, the drawings should not be construed to limit the scope of the present invention. [0010] FIG. 1 is a front view schematically illustrating a fabric permeation system according to an embodiment of the present invention. [0011] FIG. 2 is a perspective view illustrating major components of the permeation system illustrated in FIG. 1 . [0012] FIG. 3 is a front view illustrating part of a rotary permeation paddle device illustrated in FIG. 1 . [0013] FIG. 4 is a front view schematically illustrating the operation of the rotary permeation paddle device of FIG. 3 . [0014] FIG. 5 is a flow chart illustrating a method of manufacturing fabric using the permeation system of FIG. 1 . EXPLANATION ON REFERENCE NUMERALS [0000] 100 : Body 101 : Frame 110 : Fabric supply part 111 : Supply roll 112 : Tension plate 113 : Supply roller 120 : Permeation part 121 : Permeation device 122 : Permeation roller 123 : Permeation paddle 124 : Support member 125 : Height adjustment device 126 : Handle 127 : Wetting agent supply device 128 : Supply hopper 129 : Supply tube 130 : Drying part DETAILED DESCRIPTION [0032] In order to achieve the objects described above, a fabric permeation system according to the present invention, the system for permeating a wetting agent into fabric, is characterized by including a fabric supply part including a supply roll around which the fabric is wound; a permeation part 120 including a wetting agent supply device configured to accommodate and supply a wetting agent to the fabric supplied from the supply roll, at a supply hopper, a permeation device with multiple permeation paddles installed in a permeation roller at predetermined intervals for permeating the wetting agent supplied from the supply hopper into the fabric, and a height adjustment device adjusting a permeation pressure by adjusting a distance between the permeation paddle and the fabric; a drying part drying the fabric into which the wetting agent is permeated by the permeation paddle; and a collecting part winding the fabric, which passes through the drying part, around a collecting roll. [0033] In some embodiments, the permeation roller and the permeation paddle are characterized by being installed to rotate in a reverse direction with respect to a movement direction of the fabric. [0034] In some embodiments, the permeation system is characterized by further including a supply tube formed in a lower part of the supply hopper, wherein the supply tube is bent towards the permeation paddle, being located farther backward than the permeation paddle with respect to the movement direction of the fabric, such that the wetting agent is smeared on the permeation paddle and applied to the fabric. [0035] In some embodiments, an end of the supply tube is characterized by forming an inclined angle, such that the wetting agent is evenly smeared while the permeation paddle is rotating. [0036] In some embodiments, the permeation system is characterized by further including a supply tube formed in a lower part of the supply hopper, wherein the supply tube is located farther forward than the permeation paddle with respect to the movement direction, such that when the supply tube drops the wetting agent to the fabric, the permeation paddle permeates the wetting agent, being rotated. [0037] Meanwhile, a method of manufacturing fabric using the fabric permeation system according to the present invention is characterized by including step 1 of adjusting the height of a permeation paddle contacting the fabric (S 10 ); step 2 of supplying the fabric (S 20 ); step 3 of supplying a wetting agent to be permeated into the fabric (S 30 ); step 4 of rotating the permeation roller and the permeation paddle to permeate the wetting agent into the fabric (S 40 ); step 5 of drying the fabric into which the wetting agent is permeated (S 50 ); and step 6 of collecting the fabric (S 60 ). [0038] In some embodiments, it is characterized in that in step 1 (S 10 ), a contact area and a contact pressure between the permeation paddle and the fabric are adjusted by adjusting the height of the permeation paddle. [0039] In some embodiments, it is characterized in that in step 3 (S 30 ), the wetting agent is supplied to the permeation paddle through a supply tube of a supply hopper, such that the wetting agent is smeared on the paddle and then applied to the fabric. [0040] Hereinafter, with reference to the accompanying drawings, the present invention is described in detail with preferred embodiments so that a person having ordinary knowledge in the art to which the present invention pertains can easily carry out the present invention. However, in describing in detail the operation principle of the preferred embodiments of the present invention, the detailed descriptions on the disclosed functions or constitutions, are determined to make the gist of the present invention unclear unnecessarily, they are omitted. Construction of the Permeation System [0041] FIG. 1 is a front view schematically illustrating a fabric permeation system according to a preferred embodiment of the present invention, FIG. 2 is a perspective view illustrating the main constitution of the permeation system illustrated in FIG. 1 , FIG. 3 is a front view illustrating the operation principle of a rotary permeation paddle device illustrated in FIG. 1 , and FIG. 4 is a front view schematically illustrating the operation of the rotary permeation paddle device of FIG. 3 . The permeation system of the present invention is for permeating a functional wetting agent to fabric, and may be used for producing all kinds of products including clothing, shoes, bags, and hats, etc., which can be manufactured with fabric into which the wetting agent is permeated. Hereinafter, for the sake of convenience, the description is limited to clothing. [0042] The fabric permeation system according to the present invention is formed by including a body 100 , a fabric supply part 110 , a permeation part 120 , a drying part 130 , and a fabric collecting part, as shown in FIG. 1 to FIG. 4 . Here, the fabric is for manufacturing padding with excellent insulation function by being permeated with an aerogel powder, and may be used for manufacturing clothing with insulation function, in addition to padding. Also, wetting agents with heating, moisture permeation, waterproofing, antifouling, antibacterial, and flame retardant, etc. properties, in addition to insulation property, may be used for manufacturing various kinds of clothing. [0043] First, the body 100 is formed by fastening multiple frames 101 to each other, and fixes the fabric supply part 100 , the permeation part 120 , the drying part 130 , and the fabric collecting part to positions where each of them can perform their functions. The body 100 may be configured to close an inter space and include the above constituents in the inter space. [0044] The fabric supply part 110 , which is for supplying fabric requiring permeation, includes a supply roll 111 installed in a side part of the body 100 , around which fabric is wound, a tension plate 112 adjusting the fabric tight, which passes through the permeation part 120 from the supply roll 111 and is wound again around a collect roll, and a supply roller 113 installed such that the fabric which moves through the tension plate 112 is converted to an angle (for example, horizontal) optimal for permeation, while consistently maintaining a tight state. [0045] Here, as shown in FIG. 2 , the tension plate 112 is installed to contact the surface of the outermost fabric wound around the supply roll 111 at a constant tension, to supply the fabric unrolled and supplied from the supply roll 111 in a tight state. [0046] Further, as shown in FIG. 1 and FIG. 2 , the supply roller 113 , which is a member allowing the fabric wound around the supply roll 111 to be smoothly converted to a horizontal state while unrolling and moving, is installed between the supply roll 111 and the permeation part 120 . [0047] The permeation part 120 is formed by including a permeation device 121 , a height adjustment device 125 , and a wetting agent supply device 127 . [0048] First, as shown in FIG. 3 and FIG. 4 , the permeation device 121 , which is a device for permeating the wetting agent supplied from the wetting agent supply device 127 to fabric, is formed by including a permeation roller 122 , a permeation paddle 123 , and a support member 124 . [0049] First, the permeation roller 122 is installed to rotate by a supply source (not shown) such as a motor, etc., in the body 100 . Further, in one permeation roller 122 , multiple permeation paddles 123 are mounted. One or multiple permeation roller 122 may be installed as needed, in an upper part or a lower part of the fabric, or in the upper part and the lower part alternately. Of course, the same number of the wetting agent supply device 127 , which supplies the wetting agent to the permeation device 121 , as that of the permeation device 121 is installed. [0050] Also, multiple permeation paddles 123 are installed in one permeation roller 122 at predetermined intervals, and are manufactured using urethane or teflon having elasticity, so as for a contact region to be bent when contacting the fabric. Further, the permeation paddle 123 may be manufactured with a thin free end side and a thick basal end side, so as to increase contact force according to the contact region between the permeation paddle 123 and the fabric. In addition, the permeation paddle 123 is manufactured to have a width identical at least or greater than that of fabric, so as to permeate the wetting agent with respect to the full width of the fabric, and the permeation roller 122 , onto which the permeation paddle 123 is mounted, is manufactured to have a width identical or greater than that of the permeation paddle 123 . [0051] Further, the support member 124 is a member installed at a side of the fabric for preventing the fabric from being loosened when the permeation paddle 123 permeates the wetting agent by pressing the fabric. The support member 124 may be a fixed plate or a conveyor belt moving with the fabric. At this time, the belt may have a flat plane so as to be in uniform contact with the fabric. Also, the same number of the support member 124 as that of the permeation roller 122 is installed. When the permeation roller 122 is installed in the upper part and the lower part of the fabric alternately, the support member 124 is installed to arrange the fabric in a gap with the permeation roller 122 . [0052] Thus, a large amount of the wetting agent can be quickly permeated into the fabric with a constant thickness, and by adjusting the contact area and the contact pressure between the permeation paddle 123 and the fabric according to cases by adjusting the height of the permeation paddle 123 , by the support member 124 preventing the fabric from being loosened while multiple permeation paddles 123 contact the fabric and permeate the wetting agent in one rotation of the permeation roller 122 . Therefore, the permeation process time can be significantly shortened and the permeation efficiency can be increased by controlling the moving speed of the fabric and the rotating speed of the permeation roller 122 . [0053] The height adjustment device 125 , which is a device adjusting the height of the permeation device 121 , is installed to adjust the contact area and contact force between the permeation paddle 123 and the fabric, to adjust the height of the wetting agent permeated into the fabric or the height of the fabric into which the wetting agent is permeated. The height adjustment device 125 includes a handle 126 , as shown in FIG. 1 , and is installed to adjust the height of the permeation device 121 by turning the handle 126 . As another manner, a driving source such as a motor may be included to change the height of the permeation device 121 with operation of the driving source by pressing an ascending or descending button. [0054] The wetting agent supply device 127 includes a hopper to store and supply a wetting agent for providing functionality to the fabric. The wetting agent supply device 127 is formed, for example, by including a storage hopper (not shown) storing each of multiple raw materials constituting a wetting agent, and a supply hopper 128 mixing the raw materials supplied from the storage hopper at a predetermined ratio and supplying the mixture. As another example of the wetting agent supply device 127 , as shown in FIG. 2 , the wetting agent supply device may be formed with the supply hopper 128 alone, which accommodates and supplies a wetting agent where the raw materials are premixed. [0055] A supply tube 129 , which is located in the lower part of the supply hopper 128 , is located in back of the permeation paddle 123 of the permeation device 121 with respect to the transporting direction of the fabric and is bent towards the permeation paddle 123 , as shown in FIG. 4 , such that the rotating permeation paddle 123 is smeared with the wetting agent to coat it on the fabric. [0056] Also, an end of the supply tube 129 is formed to have a predetermined inclined angle, such that the wetting agent is smeared well according to a rotation angle of the permeation paddle 123 . The supply hopper 128 , specifically the supply tube 129 of the supply hopper 128 , has a width identical or similar to that of the permeation paddle 123 , such that the permeation paddle 123 applies the wetting agent evenly with respect to the full width of the fabric. Of course, an amount of the wetting agent supplied from the supply tube 129 is provided uniformly with respect to the full width of the supply tube 129 . [0057] Also, the supply tube 129 may not be bent, so as to drop the wetting agent directly to the fabric. In this case, the wetting agent supply device 127 is located farther forward than the permeation device 121 with respect to the movement direction of the fabric and may permeate the wetting agent dropped from the supply tube 129 to the fabric, while the permeation roller 122 and the permeation paddle 123 rotate in a reverse direction with respect to the movement direction of the fabric. [0058] Here, the wetting agent is for providing the fabric with insulation, heating, moisture permeation, waterproofing, antifouling, antibacterial, and flame retardant, etc. functions. Hereinafter, for the sake of convenience, the description is limited to a wetting agent for insulation including aerogel for insulation. Thus, the wetting agent includes an aerogel power and an adhesive binder, and further includes an additive, as needed. [0059] Here, aerogel is a novel material, which is light, and draws attention as an insulation material, an impact absorbing material, and a soundproofing material, etc., as described in the background art above. In the present invention, an aerogel powder is used for permeating aerogel into fabric. Further, the adhesive binder includes at least one of cellulose-based, starch-based, epoxy-based, polyvinyl alcohol-based, and urethane-based materials. In addition, the additive includes at least one of a filler or a foaming agent. The filler refers to at least one of plaster, a silica powder, and a perlite particle, and the foaming agent refers to at least one of polyacrylate polymers, sodium hydrogen carbonate, an aluminum magnesium carbonate powder, a zinc powder, calcium carbonate, and a CAS blowing agent. [0060] Meanwhile, the drying part 130 is installed in back of the permeation part 120 , so as to emit hot or warm air for drying an organic solvent and residual moisture remaining in fabric, with respect to the moving fabric into which the wetting agent is permeated. [0061] Also, the fabric collecting part includes a discharge roller 140 for moving the fabric of the supply roll 111 and a collecting roll (not shown) winding the dried fabric again. Here, the discharge roller 140 is located between the drying part 130 and the collecting roll with respect to the movement direction of the fabric, as shown in FIG. 1 , and guides the original fabric of the supply roll 111 to pass through the permeation part 120 and the drying part 130 to move horizontally, and then have a predetermined angle to be wound smoothly around the collecting roll. [0062] Also, the collecting roll provides an external force allowing movement of the fabric of the supply roll 111 . Thus, the moving speed of the fabric is controlled by the collecting roll. Of course, the moving speed of the fabric by the collecting roll is associated with the rotating speed of the permeation roller 122 and the permeation paddle 123 of the permeation device 121 . Method [0063] FIG. 5 is a flow chart illustrating a method of manufacturing fabric using the permeation system of FIG. 1 . [0064] The method of manufacturing fabric using the permeation system according to the present invention first adjusts the height of the permeation paddle 123 contacting the fabric, with the height adjustment device 125 , for adjusting the permeation thickness of a wetting agent (S 10 ). At this time, when the permeation paddle 123 is located close to the fabric and the contact area between the permeation paddle 123 and the fabric is larger, a permeation pressure permeating the wetting agent is higher, and when the permeation paddle 123 is located far from the fabric and the contact area between the permeation paddle 123 and the fabric is smaller, a permeation pressure permeating the wetting agent is lower. Thus, a distance between the permeation paddle 123 and the fabric is properly adjusted according to elasticity of the permeation paddle 123 or the properties of the wetting agent, such as degree of watery property, etc. [0065] Next, the fabric is supplied (S 20 ). To this end, a side part of the fabric which is wound around the supply roll 111 passes through the supply roller 113 and the discharge roller 140 , and is wound around the collecting roll. Thereafter, the fabric is pulled while the collecting roll is rotating, and the fabric unrolled from the supply roll 111 passes through the permeation part 120 and the drying part 130 and moves. [0066] Next, the wetting agent is supplied (S 30 ). Here, the wetting agent mixing a variety of raw materials provided at a predetermined ratio from the storage hopper storing each of the variety of raw materials, is discharged outside through the supply tube 129 of the supply hopper 128 . [0067] Next, the wetting agent is permeated into the fabric by rotating the permeation roller 122 and the permeation paddle 123 (S 40 ). Here, the wetting agent discharged from the supply tube 129 may be permeated by being smeared on the permeation paddle 123 while the permeation paddle is rotating and applied to the fabric, or may be permeated by rotating the permeation paddle 123 in a state where the wetting agent is directly dropped to the fabric. [0068] Of course, when the wetting agent is applied to the fabric using the permeation paddle 123 , the supply tube 129 is located farther backward than the permeation paddle 123 with respect to the fabric transporting direction. When the wetting agent dropped to the fabric is permeated by the permeation paddle 123 , the supply tube 129 is located farther forward than the permeation paddle 123 with respect to the fabric transporting direction. [0069] Next, the fabric into which the wetting agent is permeated is dried (S 50 ). Here, the fabric passes through the drying part 130 emitting hot or warm air, and at this time, an organic solvent and residual moisture remaining in the fabric are dried. [0070] Finally, the fabric is collected (S 60 ). The fabric dried by passing through the drying part 130 is wound again around the collecting roll. [0071] As described above, a person skilled in the art to which the present invention pertains can understand that the present invention can be carried out in different embodiments without modifying the technical sprit or essential characteristics. Thus, it should be understood that the above-described embodiments are by way of example only in every aspect, and are not intended to limit the present invention. The scope of the present invention is defined by the following claims, rather than by the detailed description. Further, it should be appreciated that all modifications or modified forms derived from the definition, scope, and equivalents of the claims fall under the scope of the present invention.	The present invention relates to a permeation system for fabric and a method for manufacturing fabric using the same, and the permeation system for permeating a wetting agent into fabric comprises: a fabric supply part; a permeation part provided with a permeation device and a height adjustment device; a drying part; and a collecting part for winding the fabric, which has passed through the drying part, around a collecting roll, thereby obtaining functional fabric of uniform quality and increasing productivity of the fabric into which the wetting agent is permeated.	3
FIELD OF THE INVENTION [0001] The field of the invention relates to processes for the preparation of carbapenems. More particularly, it relates to a process for the preparation of meropenem. BACKGROUND OF THE INVENTION [0002] (4R,5S,6S)-3-[[(3S,5S)-5-(Dimethylcarbamoyl)-3-pyrrolidinyl]thio]-6-[(1R)-1-hydroxy-ethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, commonly known as meropenem of Formula I is a synthetic, broad-spectrum, carbapenem antibiotic. [0003] U.S. Pat. No 4,943,569 discloses a process for the preparation of meropenem, by reaction of enolphosphate of Formula II, with a thiol side chain of Formula III in the presence of diisopropylethylamine, to provide a protected meropenem of Formula IV. [0004] The compound of Formula IV is then deprotected by using palladium catalyst to get meropenem. [0005] The thiol side chain of Formula III is prepared by S-deacylation of the compound of Formula V in the presence of aqueous sodium hydroxide and hydrochloric acid. [0006] Similar processes for preparing meropenem have also been disclosed in U.S. Pat. Nos. 4,888,344 and 5,122,604; Sunagawa M., et al., J. Antibiot. (Tokyo), 1990, 43(5), 519-532 and Haruki M., et al., Heterocycles, 1995, 36, 145-159. [0007] All the reported processes for the preparation of meropenem involve the isolation of the thiol side chain of Formula III, which in turn reacts with enol phosphate. Further, the preparation of thiol side chain of Formula III by S-deacylation involves a strong base such as sodium hydroxide. These processes also involve the isolation of the protected meropenem of Formula IV prior to deprotection. SUMMARY OF THE INVENTION [0008] In one general aspect there is provided a process for the preparation of compound of Formula Ia, wherein P 1 represents hydrogen or an amino protecting group, P 2 represents hydrogen or a carboxyl protecting group and P 3 represents hydrogen or a hydroxyl protecting group. The process includes: [0009] a) deprotecting thiol group of the compound of Formula Va, [0010] wherein P 1 is as defined above, R 1 is a thiol protecting group, to get a compound of formula IIIa, [0011] wherein P 1 is as defined above; [0012] b) reacting the compound of Formula IIIa with a compound of Formula IIa, [0013] wherein P 2 and P 3 are as defined above and X represents OP(O)(OR) 2 or OSO 2 R, wherein R represents substituted or unsubstituted C 1-6 alkyl, aralkyl or aryl, to get the compound of Formula Ia; and [0014] c) isolating the compound of Formula Ia from the reaction mass thereof, [0015] wherein the compound of formula IIIa is not isolated from the reaction mixture. [0016] In another general aspect there is provided a process for the preparation of compound of Formula Ia, wherein P 1 represents hydrogen or an amino protecting group, P 2 represents hydrogen or a carboxyl protecting group and P 3 represents hydrogen or a hydroxyl protecting group. The process includes: [0017] a) treating compound of Formula Va with pyrrolidine, [0018] wherein P 1 is as defined above and R 1 is a thiol protecting group, to get compound of formula IIIa [0019] wherein P 1 is as defined above; [0020] b) reacting the compound of Formula IIIa with a compound of Formula IIa, [0021] wherein P 2 and P 3 are as defined above and X represents OP(O)(OR) 2 or OSO 2 R, wherein R represents substituted or unsubstituted C 1-6 alkyl, aralkyl or aryl, to get the compound of Formula Ia; and [0022] c) isolating the compound of Formula Ia from the reaction mass thereof. [0023] In another general aspect there is provided a process for the preparation of meropenem of Formula I. The process includes: [0024] a) deprotecting thiol group of compound of Formula Vb, [0025] wherein P 1 is an amino protecting group and R 1 is a thiol protecting group, to get compound of formula IIIb, [0026] wherein P 1 is as defined above; [0027] b) reacting the compound of Formula IIIb with a compound of Formula IIb, [0028] wherein P 2 is a carboxyl protecting group, P 3 is hydrogen or a hydroxyl protecting group and X represents OP(O)(OR) 2 or OSO 2 R, wherein R represents substituted or unsubstituted C 1-6 alkyl, aralkyl or aryl, to get compound of Formula Ib, [0029] wherein P 1 , P 2 and P 3 are as defined above; [0030] c) deprotecting the compound of Formula Ib to get meropenem of Formula I; and [0031] d) isolating the meropenem of Formula I from the reaction mass thereof, [0032] wherein the compound of Formula Ib is not isolated from the reaction mixture. [0033] The details of one or more embodiments of the inventions are set forth in the description below. Other features, objects and advantages of the inventions will be apparent from the description and claims. DETAILED DESCRIPTION OF THE INVENTION [0034] The present inventors have developed a process for the preparation of meropenem and its analogues. The process does not involve the isolation of S-deprotected thiol side chain and the protected meropenem intermediate, thereby reducing the work-up time as well as the cost of production. The present inventors have also found that the S-deprotection of the thiol side chain can be carried out in the presence of pyrrolidine and eliminates the need of strong basic conditions. By following the present process, the yield and purity of the final product, meropenem, is also considerably improved. [0035] The term “protecting group” in the present invention refers to those used in the art and serve the function of blocking the carboxyl, amino or hydroxyl groups while the reactions are carried out at other sites of the molecule. Examples of a carboxyl protecting group include, but not limited to, optionally substituted C 1 -C 8 alkyl, optionally substituted C 3 -C 8 alkenyl, optionally substituted C 7 -C 19 aralkyl, optionally substituted C 6 -C 12 aryl, optionally substituted C 1 -C 12 amino, optionally substituted C 3 -C 12 hydrocarbonated silyl, optionally substituted C 3 -C 12 hydrocarbonated stannyl, and a pharmaceutically active ester forming group. Examples of hydroxyl and amino protecting groups include, but not limited to, lower alkylsilyl groups, lower alkoxymethyl groups, aralkyl groups, acyl groups, lower alkoxycarbonyl groups, alkenyloxycarbonyl groups and aralkyloxycarbonyl groups. [0036] A first aspect of the present invention provides a process for the preparation of compound of Formula Ia, wherein P 1 represents hydrogen or an amino protecting group, P 2 represents hydrogen or a carboxyl protecting group and P 3 represents hydrogen or a hydroxyl protecting group, which comprises [0037] a) deprotecting thiol group of compound of Formula Va, [0038] wherein P 1 is as defined above and R 1 is a thiol protecting group, to get compound of formula IIIa, [0039] wherein P 1 is as defined above; [0040] b) reacting the compound of Formula IIIa with a compound of Formula IIa, [0041] wherein P 2 and P 3 are as defined above and X represents OP(O)(OR) 2 or OSO 2 R, wherein R represents substituted or unsubstituted C 1-6 alkyl, aralkyl or aryl, to get the compound of Formula Ia; and [0042] c) isolating the compound of Formula Ia from the reaction mass thereof, [0043] wherein the compound of formula IIIa is not isolated from the reaction mixture. [0044] A second aspect of the present invention provides a process for the preparation of compound of Formula Ia, wherein P 1 represents hydrogen or an amino protecting group, P 2 represents hydrogen or a carboxyl protecting group and P 3 represents hydrogen or a hydroxyl protecting group, which comprises [0045] a) treating compound of Formula Va with pyrrolidine, [0046] wherein P 1 is as defined above and R 1 is a thiol protecting group, to get compound of formula IIIa, [0047] wherein P 1 is as defined above; [0048] b) reacting the compound of Formula IIIa with a compound of Formula IIa, [0049] wherein P 2 and P 3 are as defined above and X represents OP(O)(OR) 2 or OSO 2 R, wherein R represents substituted or unsubstituted C 1-6 alkyl, aralkyl or aryl, to get the compound of Formula Ia; and [0050] c) isolating the compound of Formula Ia from the reaction mass thereof. [0051] A third aspect of the present invention provides a process for the preparation of meropenem of Formula I, [0052] which comprises [0053] a) deprotecting thiol group of compound of Formula Vb, [0054] wherein P 1 is an amino protecting group and R 1 is a thiol protecting group, to get compound of formula IIIb, [0055] wherein P 1 is as defined above; [0056] b) reacting the compound of Formula IIIb with a compound of Formula IIb, [0057] wherein P 2 is a carboxyl protecting group, P 3 is hydrogen or a hydroxyl protecting group and X represents OP(O)(OR) 2 or OSO 2 R, wherein R represents substituted or unsubstituted C 1-6 alkyl, aralkyl or aryl, to get compound of Formula Ib, [0058] wherein P 1 , P 2 and P 3 are as defined above; [0059] c) deprotecting the compound of Formula Ib to get meropenem of Formula I; and [0060] d) isolating the meropenem of Formula I from the reaction mass thereof, [0061] wherein the compound of Formula Ib is not isolated from the reaction mixture. [0062] Enol-phosphate of Formula Ia and thiol side chain of Formula Va can be prepared by processes reported in the prior-art as mentioned earlier. Thiol side chain is dissolved in an organic solvent and cooled to a temperature of about 25° C. or less. Pyrrolidine is added to the reaction mixture and stirred for a sufficient time to effect deprotection of the thiol group. The reaction mixture so obtained can optionally be treated with an aqueous mineral acid solution. Enolphosphate is added to the organic layer of the reaction mixture at a temperature of about 0° C. or less. The reaction mixture is stirred in the presence of a base for a sufficient time at the same temperature to effect the coupling reaction. The reaction mixture is subsequently hydrogenated using a palladium catalyst in the presence of a non nucleophilic buffer. Examples of buffers include morpholinopropanesulphonic acid and morpholinoethanesulphonic acid. An aqueous buffer comprising N-methylmorpholine mat also be used. [0063] After completion of the reaction, the solid product is isolated from the aqueous layer, washed with an organic solvent and dried to get meropenem. [0064] While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention. EXAMPLE 1 Preparation of Meropenem [0000] 4-Nitrobenzyl (2S,4S)-4-(acetylthio)-2-[(dimethylamino)carbonyl]pyrrolidine-1-carboxylate (50 g) was dissolved in N,N-dimethylformamide (500 ml) and cooled to −5° to 0° C., followed by drop-wise addition of pyrrolidine (13.5 g) at the same temperature. The reaction mixture was stirred at −5° to 0° C. for 30 minutes and cooled to −40° to −35° C. 4-Nitrobenzyl (4R,5R,6S)-3-[(diphenoxyphosphoryl)oxy]-6-[(1R)-1-hydroxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (Enolphosphate; 50 g) was added to the reaction mixture, followed by the addition of diisopropylethylamine (14.0 g) and stirring for 60 minutes at the same temperature. The reaction mixture was then poured into a mixture of ethyl acetate (500 ml) and water (500 ml). The ethyl acetate layer was separated and mixed with buffer containing N-methylmorpholine in water (500 ml) at a pH of 7.0. The hydrogenation of the reaction mixture so obtained was carried out at ambient temperature over palladium-carbon and the aqueous layer was separated after hydrogenation. Acetone (2 L) was added at 0°-5° C. to the aqueous layer of the reaction mixture to obtain the title compound in crystalline form. Yield: 20 g HPLC Purity: 98% EXAMPLE 2 Preparation of Meropenem [0000] 4-Nitrobenzyl (2S,4S)-4-(acetylthio)-2-[(dimethylamino)carbonyl]pyrrolidine-1-carboxylate (30 g) was dissolved in dichloromethane (90 ml) and cooled to -10° to 0° C., followed by drop-wise addition of pyrrolidine (8.0 g) at the same temperature. The reaction mixture was stirred at −5° to 0° C. for 30 minutes and poured into 5% hydrochloric acid (150 ml), followed by separation of the organic layer. 4-Nitrobenzyl (4R,5R,6S)-3-[(diphenoxyphosphoryl)oxy]-6-[(1R)-1-hydroxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (Enolphosphate; 30 g) was dissolved in dimethylformamide (150 ml) and cooled to −40° to −50° C., followed by the addition of dichloromethane solution containing 4-nitrobenzyl (2S,4S)-2-[(dimethylamino)carbonyl]-4-mercaptopyrrolidine-1-carboxylate. Diisopropylethylamine (8.4 g) was added drop-wise to the reaction mixture so obtained and stirred for 60 minutes at −40° to −30° C. The reaction mixture was then poured into a mixture of ethyl acetate (300 ml) and water (300 ml). The ethyl acetate layer was separated and hydrogenated at pH 7.0 over palladium-carbon and the aqueous layer was separated after hydrogenation, followed by treatment with activated carbon. The solution so obtained was filtered and acetone (2 L) was added at 0°-5° C. and stirred for 3 h at the same temperature. The reaction mixture was filtered, washed with acetone and dried to obtain the title compound. Yield: 11 g HPLC Purity: 98% [0071] While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.	The invention relates to processes for the preparation of carbapenems. More particularly, it relates to a process for the preparation of meropenem.	2
TECHNICAL FIELD The present disclosure provides a combination of a fixing element and a support element for a hob in a worktop into which the hob is to be installed. BACKGROUND EP 1 977 169 B1 discloses a combination of a fixing element with a support element in which the fixing element comprises a spring and is made up of a substantially planar and linear resilient element, the first end of which is free while the second end is constrained to the support element. The linear arrangement of the spring exhibits the disadvantage of reducing the compression force which the spring is capable of exerting against the structural element in the installed configuration of the hob. This reduced compression force does not effectively prevent the installed hob from lifting from the contact surface of the worktop, which results in infiltration of liquids accidentally spilled on the worktop or used for example during cleaning of the worktop. Moreover, the elongate arrangement of the spring means that the constrained end thereof must be fixed at a level sufficiently below the surface of the worktop to enable the spring to engage effectively and exert its resilient action. This type of limitation entails modifications to the structure of the hobs, especially for those which are of a thinner design, if it is to be possible to use the same fixing element with a variety of models of hob. Furthermore, unlatching of the spring from the wall of the cut surface in the worktop with which the latter is engaged may only be effected from beneath the installed hob. As a consequence, in the event of repair or maintenance of the hob, anything located beneath it (for example an oven built into the same cabinet or drawers) must be removed to provide access. U.S. Pat. No. 3,386,108 discloses a combination of a support element and a fixing element in which the fixing element is engaged beneath the support element and the installed hob is held in place in the worktop by means of a tie rod which is screwed in under the worktop. Said solution is highly complex and difficult to adapt to the various depths of hobs and work surfaces which are currently distributed commercially. Finally, GB 2 241 980 A discloses a combination of a fixing element and a support element according to the preamble of the main claim. The fixing element described therein is a resilient element removably fixed to a profile of the hob structure by welding, riveting or by means of screws, so making the solution costly in terms of assembly. Said solution provides a V-shaped resilient element in which one end is constrained and the second is free. A tab-like surface extends from the latter in a substantially orthogonal direction for the purpose of creating a surface which engages with the lower edge of the worktop with the aim of providing resistance to lifting of the hob installed in the worktop. Said known solution cannot be adapted to the various depths of worktop into which a hob may be installed. It is thus not a “universal” solution. Furthermore, for this hob too, unlatching of the fixing means may only be effected by working from the underside of the worktop. SUMMARY The object of the present disclosure is therefore to provide a combination of a fixing element and support element for a hob which overcomes the above-stated disadvantages and is simple and economical to manufacture. According to the disclosure, said object is achieved thanks to the features set out in the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS Further advantages and features of the device according to the disclosure will emerge from the following detailed description, which is provided purely by way of non-limiting example, with reference to the attached drawings, in which: FIGS. 1 , 2 and 3 respectively show a perspective view, a side view and a plan view of a preferred configuration of the fixing device of the present disclosure; FIG. 4 shows a preferred configuration of the support according to the disclosure with which the fixing device is coupled; FIGS. 5 and 6 show the operations of connecting the fixing element and the support element described in the preceding figures; FIG. 7 describes the compression of the resilient element of the fixing device of the preceding figures carried out with a tool which acts on the free end of the fixing element; FIGS. 8 and 9 describe the sequence for uninstalling a hob using a tool with a portion having a flat profile. DETAILED DESCRIPTION With reference to the above-stated figures, a hob H is described, in particular an electric hob, comprising a sheet G of vitreous ceramic material fixed in known manner to a housing C located therebeneath, the latter being capable of containing both the heating elements and the power supply and control means for said elements. The sheet G has an upper surface on which the pans are normally placed when foodstuffs are being cooked, and a lower surface L joined to the housing C and concealed from view when the hob is installed in a carrier element W, such as for example a worktop. A sealing gasket (not shown) may be arranged around the periphery of the frame or between the carrier element W of the worktop and the sheet G, to prevent water from getting inside housing C therebeneath. It is known from the prior art that a worktop W in which the hob H is to be installed has an opening, usually rectangular in shape, into which the hob H is to be inserted and fixed for subsequent use. The worktop is usually of wood or marble, but may be of synthetic material or be made from a plurality of materials. The housing C of the hob H is preferably made of metal or plastics material or and has peripheral vertical walls in which are located support elements or portions. According to the disclosure, the housing C is coupled to the carrier element W in which it is installed, by means of at least one support element S, which is in turn coupled to at least one fixing element F. Advantageously, each support element S is a pocket-like seat P, wherein each pocket is provided with a central strip B for the fixing element F and with two slots HI and LO located at the opposite ends of said central strip B. Advantageously, the central strip B protrudes towards the outside of the housing C relative to the vertical plane of the peripheral wall. In the case of a sheet metal housing, said strip is a region of sheet metal obtained by means of two parallel cuts in the sheet metal and necessarily plastically deformed outwards. According to a preferred embodiment, the fixing element F comprises a resilient device (EE, X, FE), preferably a V-shaped hook which, when assembled with the support element S, has a free end FE opposite to a constrained end EE and capable of coupling to said support means S. The V-shaped hook preferably comprises a fold X located between said constrained end EE and said free end FE, in which the vertex is in a portion opposite to said ends. In alternative embodiments (not shown), the resilient element E comprises further concertina-like central folds XC (illustrated generally in FIG. 5 ) in an odd number so that the both free end FE and the constrained end EE are always on the same side relative to the central fold X. The presence of one or more folds between the free end FE and the constrained end EE increases the resilient force which the spring is capable of exerting, in particular against the vertical wall of the incision in the worktop when the support of the component, in particular a hob, is installed therein. This increased force opposes lifting of the hob installed in the worktop, so improving the resistance of the assembly to infiltration by liquids, such as for example those used for cleaning and liquids which overflow accidentally during use of the hob H. Unlatching of the fixing element F assembled with the support S from the carrier element W, i.e. in the assembled configuration of the combination, is effected by compressing the free end FE of the fixing element F. Compression CX of the free end of the fixing element, shown in FIG. 8 , releases the resilient element from engagement against the vertical wall of the incision in the worktop so enabling extraction of the hob from the seat. According to the disclosure, the free end FE of the fixing element comprises a tab-like portion L which extends substantially in a direction Y parallel to the constrained end. In a preferred embodiment, the tab-like portion L is capable of permitting unlatching of the fixing element F assembled with the support element S of the component from the carrier element W by means of a compression action exerted on said portion L, in particular when the hob is installed in a worktop. The extent and shape thereof are such as to permit latching and compression thereof by bringing the end portion LE thereof closer to the lower surface of the sheet G, during the unlatching operation, but without interfering with said sheet. This arrangement makes it possible to unlatch the fixing element F with access being gained from the upper side U of the carrier element W, the worktop, without there being any need to work from the underside thereof. Advantageously, a tool T may be provided for unlatching the fixing element F assembled with the support element S of a component H, in particular for unlatching a hob H from a carrier element W, the latter in particular being a frame which supports or surrounds the hob. Advantageously, the tool T is configured for unlatching a plurality of fixing elements F, in particular being configured so as to be capable of exerting virtually simultaneous compression on a plurality of tabs, preferably arranged in a rectilinear direction Z, as shown in the sequence of FIGS. 7 , 8 and 9 . Said tool T preferably has a portion having a flat profile LL, for example a blade, capable of being inserted between the support element of the component S and/or G and/or FR and the worktop W in which it is installed, and is configured for substantially simultaneously compressing a plurality of tabs of said fixing elements. In a preferred embodiment, the free end furthermore comprises means SW for countering lifting of the support element from the carrier element, in the assembled configuration, preferably with a saw-toothed profile, as shown in FIGS. 1 and 3 . Advantageously, coupling between said fixing means F and said support means S may be implemented by applying one or more hooks F to the described pockets P as described below. In a preferred configuration of the fixing element, the constrained end thereof incorporates resilient snap-on latching means to said support element S, in particular to the pocket P. Preferably, a protruding element SLG is located in the constrained end EE, which protruding element is capable of being inserted in a slot of the pocket-like seat P, preferably the lower slot LO, and, for latching at the level of a region opposite the pocket P (the upper slot HI in the case shown), a resilient latching element with said central strip B comprising a deformable resilient portion EL. The resilient latching element is opposite to said protruding element SLG and is capable of releasing the hook F, at least on a portion of the central strip, by rotation of the hook around the slide element SLG and by snap-on deformation of a resilient portion EL thereof during coupling with the central strip B. The latching sequence is shown in FIGS. 4 , 5 and 6 . The fixing element F may preferably be fixed reversibly. In this described configuration, the width W 1 of the resilient latching element EL is greater than the width W 2 of said tab-like portion L and identical to the width of the free end FE. Other equivalent arrangements are applicable for the same purpose, as are, however, other known reversible coupling methods between the fixing element and the support, such as for example those described in EP 1 977 169, or by means of screws or rivets. In one preferred variant, the hook is made from spring steel treated against oxidation processes, for example by means of a passivation process such as a burnishing process. The same device is also applicable to other types of hobs and other built-in household electrical appliances, for example ovens or refrigerators. Further variants of the present disclosure may be obtained by combining the individually described features. For instance, the combination of a fixing element with a support element in which the fixing element F comprises a resilient fixing element EE, X FE, wherein the fixing element may exert a greater force for countering extraction of the hob H installed in a worktop W, and wherein uninstallation of the installed hob is a rapid procedure for the operator who may work from the upper side U of the hob, without there being any need for further operations to gain access to the lower portion of said hob. Furthermore, the combination according to the disclosure makes it possible to install and fix said hob of a known depth in any currently commercially available worktop. The combination according to the disclosure thus assumes the nature of an economical and universal fixing system. More generally, a description has been provided of a combination of a fixing element and a support element which is economical and versatile for wider use.	A universal cooking hob fixing system for the installation of the cooking hob in a worktop is disclosed. The fixing element has a hooking snap element to the cooking hob support and presents elastic means for keeping the hob into the installed position, suitable to prevent its lifting. The configuration of the hooking snap elements allows the release of the hob by acting from the top side of the installed hob, with a specially shaped tool.	5
[0001] The invention relates to improvements on MOS logic circuits working in current mode, and optimization of speed and power consumption of source coupled logic. BACKGROUND [0002] MOS Current Mode Logic (MCML) is a differential logic family. MCML is beneficial for high speed mixed signal integrated circuits (ICs). It has been shown to provide a number of advantages over static CMOS including less power consumption at higher frequencies, less sensitivity to switching noise, and increased process voltage temperature (PVT) immunity. [0003] Subthreshold Source Coupled Logic (STSCL) is also a differential logic family with similar circuit topology as MCML. However, STSCL is most beneficial for ultra-low power and low frequency applications. Depending on the leakage current, activity factor, and operation frequency, STSCL can have advantages (e.g. power reduction, tunability) over static CMOS. [0004] Prior art current mode CMOS logic circuits are described for example in patent publication “CURRENT MODE LOGIC DIGITAL CIRCUITS”, US2009219054 (A1), Toumazou Christofer [GB], and Cannillo Francesco [GB]. It describes biasing and general design of MOS current more logic (MCML) including STSCL. THE INVENTION [0005] Switched Bulk Source Coupled Logic (sbSCL) according to the invention is a differential logic circuit variant that is able to configure itself as either MCML or STSCL. The configuration is done by switching the bulk connection of a PMOS load as is further described below. sbSCL has the advantages of both MCML and STSCL. [0006] The object of the invention is to produce a more versatile logic circuit that can operate properly with either very high frequencies or with extremely low power consumption with good PVT immunity. This object is achieved by an insulated gate field effect transistor current mode logic circuit that comprises differential source coupled circuitry as input, and load transistors for transforming the current signal to voltage output. According to the invention the load transistor or transistors for each leg of current mode output leg are configurable so that the bulk of an operational load transistor in use is connected to drain of the same transistor, when the circuit is used in subthreshold mode as STSCL. The bulk of the load transistor in use is connected to source of the same load transistor in use or the bulk may be connected to a voltage source, when the logic circuit is used as MCML circuit. The voltage source is typically positive operation voltage of the circuit for PMOS load transistor bulk, it may be different circuit node than the source, as can be seen later. [0007] The configuration of the load transistors may be done by switches that connect the bulk contact to either drain of the same transistor or to constant voltage, typically to source contact that is connected to the power rail of the circuit. Then each leg of the circuit needs one load transistor and two switches for selecting the bulk connection to source or to drain. [0008] In following this embodiment is described with reference to figures. The other embodiments include use of two load transistors for each differential circuit output leg. One of the two transistors is used in STSCL mode only, and its drain and bulk terminals are connected together, the other one has its bulk connected to source or to other voltage, that allows the MCML operation. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a conceptual schematic diagram of an embodiment of sbSCL according to the invention. [0010] FIG. 2 is a conceptual schematic diagram of an embodiment of sbSCL according to the invention. The diagram includes CMOS transistors ( 202 , 203 ) in replace of conceptual switches. These transistors may be substituted with any suitable switching means. [0011] FIG. 3 presents alternative ways to replace transistor M 6 of FIG. 1 using two transistors with different bulk configurations. DETAILED DESCRIPTION [0012] An embodiment of our invention, a block diagram of a generic n-input sbSCL gate is shown in FIG. 1 . The sbSCL gate consists of a NMOS network ( 104 ), a Bulk Switching Unit ( 102 , 103 ), and a Voltage Swing Control VSC ( 105 ). sbSCL, which is described in more detail below, is able to switch the bulk connection of the PMOS load depending on the operation frequency or required V SWING ; the V SWING is equal to \|V out,1 −V out,1′ \|. When the bulk is connected to the source, the sbSCL logic operates as MCML. If the bulk is connected to the drain, the sbSCL logic behaves the same as STSCL. Thus, sbSCL gives the benefits of both MCML and STSCL. [0013] The switching between two operation modes may be done also by using two transistors like in FIG. 3 embodiments A to D. The first transistor has its bulk connected to drain and the second has its bulk connected to source or to a suitable other voltage, for example to power rail Vdd as in FIG. 3 embodiment B. This configuration can be made most advantageously connecting the two PMOS load transistors in series. They may have common bulk connected to upper transistor drain and the lower transistors source and bulk is connected to the same node, so that the bulk of lower transistor is connected to its source, as in FIG. 3A . For STSCL operation the lower transistor is turned on and the upper transistor works essentially as controllable load resistor that is controlled by Voltage Swing Control (VSC). Drawback is that two large size (long channel) load transistors are needed, and both load transistors need a swing control that can also output low output voltage for turning the transistor on. If the bulk of the two transistors are electrically separated, the lower transistors bulk may be connected to the power rail instead of the source of the same transistor as in FIG. 3 embodiment B. The transistor that is not used as controlled load transistor can be considered as an additional small series resistor. [0014] If two parallel transistors are used with same principle like in FIG. 3 embodiments C and D, the transistor with bulk connected permanently to drain would need an additional switch to disable the source-bulk diode in MCML mode, in order to prevent the diode turn on. The switch may be connected in series with the other load transistor as in 3 C, or it may be a transistor, that can disconnect the bulk only as in 3 D. There seems to be no obvious benefit for these configurations compared to other embodiments of the invention, especially FIGS. 2 and 3A . The two bulk connections need to be electrically separated, unlike in FIG. 2 and FIG. 3 embodiment A. [0015] The NMOS network ( 104 ) within the sbSCL of FIG. 1 consists of stacked source-coupled differential pairs. The NMOS network is used to steer the bias current I SS to one of the two output nodes (V out,1 or V out,1′ ) based on the differential input signals V in,1 =V in,1 −V in,1 ′ to V in,n=V in,n −V in,n ′. The bias current I SS can be generated by any type of current source. The output resistance of the M 5 and M 6 is called R p , and it converts the steered bias current I SS back to the voltage domain in order to drive subsequent sbSCL gates. Thus, the V SWING is equal to R p *I SS .This topology allows for both combination and sequential gates whose logic depends on the connection of the NMOS source-coupled pairs. [0016] The Bulk Switching Unit ( 102 , 103 ) in FIG. 1 is used to switch the bulk connection of the PMOS load depending on the operation frequency or required V SWING . For high operation frequencies, it is desirable to have a larger V SWING that can exceed the source-to-bulk diode turn on voltage of M 5 or M 6 . To prevent this diode from turning on, S 1 is switched on (and S 2 off). S 1 connects the bulk to source of the PMOS load as in MCML. For operation at lower operation frequencies (i.e. subthreshold voltage levels), the bulk is connected to the drain by having S 2 on (and S 1 off). This provides a bulk-to-drain connection of the PMOS load as in STSCL. In STSCL, VSWING must not exceed the source-to-bulk diode turn-on voltage in M 5 and M 6 . [0017] The implementation of the Bulk Switching Unit ( 202 , 203 ) is made using NMOS and PMOS transistors as shown in FIG. 2 . The voltage applied to node/determines the bulk connection of the PMOS load ( 201 ). When the voltage at/is low enough to turn on M 1 and M 3 transistors (and M 2 and M 4 off), there is a bulk-to-source connection. When the voltage at/is large enough to turn on the M 2 and M 4 transistors (and M 1 and M 3 off), there is a bulk-to-drain connection. The location of the M 1 and M 2 (and M 3 and M 4 ) may be interchanged. [0018] The Voltage Swing Controller (VSC) is the same as implemented in MCML and STSCL systems. It is used to ensure the desired V SWING is attained despite global variations (e.g. temperature, process corners). One VSC can be used for multiple sbSCL gates. The desired V SWING can be programmed within the VSC. The VSC sets the V SWING by adjusting the V p and V N . [0019] Note that term “transistor” can include bipolar-junction transistors and other types of transistors not yet know or developed. The bulk switches may be any suitable controllable switching devices. MOS transistor as load transistor can be replaced with any suitable field effect transistor, not limiting to metal gate and silicon substrate or channel. The word MOS is used in the description as synonym to any insulated gate field effect transistor in general. The word MOS transistor means therefore also polysilicon gated transistors that have other insulator than oxide, as they are generally referred as “MOS”, even they are not metal gated oxide insulated. Other semiconductor materials than silicon may be used as channel material. There may be also bipolar or other type transistors used as part of the circuit.	A field effect transistor current mode differential logic circuit comprising load transistors for converting the current output of each differential leg current to voltage output, and means for configuring the bulk of each differential leg's load transistor to be connected to the drain of the load transistor for use the logic circuit in Subthreshold Source Coupled Logic (STSCL) mode, and means for configuring the bulk of each leg load transistor to be connected to a voltage or to source of the same transistor for use in MOS current more logic (MCML) operation.	7
STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon. BACKGROUND OF THE INVENTION Many different modulation techniques are available for the transmission of digital data. Among these are differential phase shifted keyed modulation techniques. This invention relates to an improvement in differential phase shift keyed transmission of digital data signals by utilizing three different phases of a carrier frequency signal. It is an object of this invention to show how both data and data synchronization information may be carried simultaneously in a single signal transmission. It is also an object of this invention to permit the carrying of uniquely identifiable character or frame synchronization information within the transmitted data stream. Other objects and advantages of the invention will become apparent from the following description. It is noted that the invention may be utilized in a digital data modem which provides the interface to a coaxial transmission media of a time division multiple access bus communication system. The modem serves to transmit and receive information by modulating and demodulating the digital data. The tri-phase shift keyed modulation technique incorporated in the modem permits both data and data synchronization signals to be transmitted at a single frequency which are then differentiated by phase as opposed to encryption of the synchronization word. SUMMARY OF THE INVENTION A differential tri-phase shift keyed modulation system is provided. A phase splitter is used to obtain three equally spaced phases of an oscillator signal. Switch means responsive to an input data signal selects one of the three phases and applies it to an amplifier for transmission. A receiver/demodulator is utilized and it is comprised of a delay line and phase shifter connected to a phase demodulator for developing a clock synchronizing signal at the data rate. There is also another delay line and a second phase demodulator for detecting the signal data content. Finally, there is utilized a third phase shifter and phase demodulator for detecting a shift of transmission signal phase. DESCRIPTION OF THE DRAWINGS FIG. 1 shows in block form the tri-phase transmission system of the present invention; FIG. 2 shows in block diagram form a receiver/demodulator for the tri-phase transmitter; FIG. 3 illustrates the phase splitter utilized in the tri-phase transmission system of FIG. 1; and FIG. 4 shows a vector diagram representation of the three outputs of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the tri-phase transmitter system, shown in FIG. 1, oscillator source 101 preferably sinusoidal in nature, is utilized as an input to phase splitter 104. Phase splitter 104 has transmitter on/off control 103 comprising switchable connections means. FIG. 3 details phase splitter 104. Switchable amplifier 120 under control 103 selects either oscillator 101 of FIG. 1 for transmission or ground reference 102, when no transmission is required. Amplifier outputs 114 and 115 are, by design, in phase opposition, one to the other. Amplifier 120 may be a commercially available integrated circuit type such as the MC 1545. Three phase splitter outputs A, B, and C are derived from the outputs 104 and 105 through phase shifting means 121 and 122 for signal A, 123 and 124 for signal B and 125 with 126 for signal C. FIG. 4 is a vector diagram representation of these three outputs arbitrarily relabeled 00, 01 and 10. By proper adjustment of resistors 121, 123 and 126 the phase relationship of the three output vectors can be caused to be shifted by 120° for any one vector with respect to any other vector. Two of said signals may then be used as inputs to switchable amplifier 105 (FIG. 1) and the third as an input to switchable amplifier 106. The output of amplifier 105 may be used as the other input to amplifier 106. Switchable control means consisting of three state up/down counter 111 may then be utilized for selection of the three different signals available from the phase splitter. Three state counter 111 may be formed from a four state counter with appropriate double count up, or double count down gating means causing an immediate count through the 11 state of a four state counter. Counter 111 would operate under the timing control of an input clock pulse which in turn may be inhibited by gate 110. If data input 112 is held in the positive data state the counter will proceed through the sequence 00, 01, 10, 00, 01, etc. If input 112 is held in the negative data state, counter 111 will proceed in the sequence 00, 10, 01, 00, 10, etc. Switchable amplifier 105 will pass input 00 whenever counter 111 outputs is of this value. Likewise, amplifier 105 will pass input signals 01 when counter 111 outputs is of that value. Amplifier 106 will pass input 10 when counter 111 output is of that value. The output of amplifier 105 will be selected and passed by amplifier 106 except when counter 111 is in the 10 state. Thus, amplifier 106 will pass onto a coax cable or radio antenna, or other transmission means, a signal which is selected from the three available signal phases in accordance with the changes of state of data input 112. Amplifier 106 may contain or drive bandpass filter means which is desired to limit the spread of transmission energy outside of what is required for proper reception. Additionally, if data input 112 is interrupted and gate 110 simultaneously interrupts the counter clock input then no change of selected signal phase will occur. In the normal mode of operation each data bit input at 112 will correspond with a phase advance selection or a phase decrement selection depending on whether the input bit is a 1 or 0 state. Periodic frame synchronization indications can be introduced by stopping the data input and inhibiting the clock at gate 110. Amplifier 105 and 106 may be the same as used for amplifier 120. A receiver/demodulator for the tri-phase transmitter of FIG. 1 is shown in FIG. 2. Input bandpass amplifier 201 may be optionally utilized to improve signal amplitude and to reject unwanted signals from the transmission media. Amplifier 201 drives signal storage means 202 comprising a delay line capable of storing one full bit duration of the transmitted signal modulation. Storage means 202 is centered tapped 212 as shown. Bandpass amplifier 201 is also used to drive phase shifters 203, 206 and 209. Phase demodulator 204 is connected to the output of phase shifter 203 and delay line center tap 212. Phase shift 203 is initially adjusted so that no relative phase shift exists between phase shifter 203's output and input 212 when a continuous unmodulated signal at the frequency of oscillator 101 (FIG. 1) is used to drive the receiver. Comparator 205 is used to amplify and restore an on/off nature to the incident signals. Recalling that in the normal mode the transmitter will advance or retard the selected signal transmission phase by 120° for each input data bit. The operation of demodulator 204 can be seen to be the vector product of each selected signal against each prior signal for the first half bit of the signal duration and then the demodulator product will be vector multiplication of the transmitted signal against itself. These products will first be a negative signal and after the half bit delay will be a positive signal. Comparator 205, with appropriate low pass input filtering, if desired, will convert this phase modulator product sequence into a 50% duty cycle bit rate clock. Demodulator 207 is fed with phase shifter 206 output and the fully delayed output of delay line 202. Initial adjustment of phase shifter 206 is such as to create a 90° relative phase shift of the modulator inputs when a continuous unmodulated signal at the frequency of oscillator 101 is fed into the receiver. Operation of this demodulator can be visualized from the vector diagram of FIG. 4. Arbitrarily assuming that any previous transmission was a signal with the vector representation 00 then the current bit transmission could be either 01, or 10, in the normal mode of operation. If the present transmission were vector state 01 s then the demodulator 207 would output a positive vector product. If, on the other hand, the current transmission were signal 10 phase shifter 206 would present dashed line vector 10 s , to the demodulator, which would in turn create a negative vector product. By inspection it can be seen that successive transmission selections corresponding to clockwise vector selections will always produce positive demodulator 207 outputs. In a similar fashion successive counter-clockwise selection vector transmission will always produce negative demodulator products. These operations are consistent with the up/down counter 111 (FIG. 1) transmitter phase selection under the control of data input 112. Comparator 208, with appropriate low pass input filtering, if desired, will then convert the output of 207 to an on/off digital signal of approprate amplitude. The fully delayed output of delay line 202 is also utilized as an input to demodulator 210 along with the output from phase shifter 209. Phase shifter 209 is initially adjusted for 0° relative demodulator input phase shift when the receiver is fed from a continuous unmodulated input at the frequency of oscillator 101. In the normal mode of operation 210 will output the vector product of the current signal transmission and the previous bit period transmission. Inasmuch as these signals will always be in a 120° phase relationship this product will always be negative, in the normal mode of operation. In the unusual mode, where the data and the clock input to counter 111 is interrupted, for a bit period, the continuation of the previous phase of signal transmission will permit the demodulation of the current signal and the previous signal to be in phase and the demodulated product to be positive. Thus, demodulator 210 uniquely detects the frame synchronization signal caused by an interruption in the data transmission process. The invention is not limited to particular amplifiers, phase shifters or other elements but may be built with different well known elements in accord with these descriptions, in order to fit particular needs, without departing from the scope of the invention.	A differential tri-phase shift keyed modulation system permits both data and data synchronization signals to be transmitted at a single frequency which are then differentiated by phase.	7
BACKGROUND OF INVENTION An apparatus designed to obtain mechanical energy from the atmosphere or water. 1. Field of the Invention The Atmospheric/Aqua Turbine is most closely related to the Wind-Charger, the Windmill and the Hydroelectric Water Turbine. The Atmospheric/Aqua Turbine is an apparatus that can be incorporated into a vehicle for the purpose of extracting mechanical energy from the resistance of the atmosphere or water when the vehicle or boat it is installed on is in motion. 2. Description of Prior Art The Wind-Charger, the Windmill and the Hydroelectric Water Turbine all three convert wind or water velocity into mechanical energy at fixed locations. They all depend on the wind blowing or water flowing in order to produce mechanical energy which is used to produce electricity or to pump water. The Atmospheric/Aqua Turbine is designed to extract mechanical energy from the atmosphere or water by being incorporated into the configuration of a vehicle. The Atmospheric/Aqua Turbine has a scoop which scoops up atmospheric pressure or water and passes it through two fan chambers in order to extract mechanical energy from the atmosphere or water. The Atmospheric/Aqua Turbine will operate when the vehicle it is installed on is moving and depends on that movement instead of depending on the wind to blow or water to flow. SUMMARY OF THE INVENTION It is the object of this invention to harness the resistance the atmospheric pressure, 14.7 psi at sea level, presents to an automobile, train, airplane or boat being moved from one location to another and turning it into mechanical energy that can be used to perform a task. This theory can be applied to water pressure. BRIEF DESCRIPTION They are many ways the Atmospheric/Aqua Turbine can be constructed as long as the theory of using the resistance atmosphere pressure or water presents to a moving vehicle of any type on land the air or in water and turning it, resistance, into mechanical energy is employed. Three of the most feasible ways the Atmospheric/Aqua Turbine can be constructed follow: 1. Air or water is caught in two scoops and is delivered to the fan chamber where the pressure turns the fans which are attached to a common shaft that extends the entire length of the fan chamber with a gear box in the center of the shaft to transfer power produced. 2. Air or water is passed though a single fan chamber to produce power. 3. Using a single air scoop and two fan chambers which are connected together with a shaft which has a pulley attached to the middle of the shaft, a V type belt for connecting the Atmospheric/Aqua Turbine to the task to be preformed. The size of the Atmospheric/Aqua Turbine determines the maximum mechanical energy it can produced. Therefore, the Atmospheric/Aqua Turbine need not be a certain size as long as enough mechanical energy is produced to perform the assigned task. FIG. No. 1 and 2 pertain to the Preferred Embodiment. FIG. No. 1 is a diagonal side view of the Atmospheric/Aqua Turbine with the half cone covers closed. FIG. No. 2 is diagonal side view of the Air Scoop with the two Half Cone Covers open. DESCRIPTION OF PREFERRED EMBODIMENT The Atmospheric/Aqua Turbine can be manufactured using metal or plastic. Mechanical energy is produced by air being caught in the air intake scoop 1 where the air pressure is increased due to the fact that it is being pushed into the intake scoop 1 at the rate of speed the vehicle on which it is installed is traveling. The air under pressure passes from the air scoop 1 into a pre-fan tube adapter 2 then into two pre-fan chamber tubes 3 escaping through two fan chambers 4 where a fan 5 in each fan chamber is turned. The two fans 5 are mounted at each end of a common shaft 7 which extends from one fan chamber 4 to the other fan chamber 4 . The air after passing through the fan chamber 4 then returns to the atmosphere by way of two exhaust tubes 6. A pulley 8 mounted on the common shaft 7 half way between the two fans 5 is connected to a generator 11 using a V type belt 9. The pulley 8 in the center of shaft 7 is ten times the size of the pulley 10 on the generator 11 thus increasing the rotation of the generator 11 to ten times that of the shaft 7. The power generated by the generator 11 is sent by two electrical lines 12 to the control box 13 then by electrical lines 14 to the battery pack 20. The control box 13 also regulates the air let into the air scoop 1 to assure constant rpm. This is accomplished by the control box 13 sensing the rpm of the common shaft 7 on which the fans 5 are mounted. A monitor 21 is located near the right end of shaft 7. The monitor monitors the rpm of shaft 7 and sends a signal to the control box 13 to adjust the two half cone covers 17 which are attached to the forward end of the air intake scoop 1. If the rpm of shaft 7 is less than the desired rpm the control box 13 sends DC current thorough the two electrical lines 28 to the open limit switches 19. The DC current flows from the open limit switches 19 through the electrical lines 31 to the DC motors 15 to cause the DC motors 15 to rotate the worm screw 16 in a counter clockwise direction thereby causing the half cone covers 17 to move toward the open position. The opening action of the two half cone covers 17 allows more air to enter the air intake scoop which increases the rpm of shaft 7 until the desired rpm of shaft 7 is reached. At the time the desired rpm is reached the control box 13 interrupts the flow of DC current through electrical lines 29 to the open limit switch 19. If the desired rpm is not reached by the time the two half cone covers. are opened to 25 degrees the stop lug on the stop lug guide 25 engages the open limit switches 18 preventing the two half cone covers 17 from opening beyond that point by interrupting the flow of DC current through electrical lines 31 to the DC motors 15. If the rpm is greater than the desired rpm the control box 13 sends DC current through the two electrical lines 28 to the closed limit switches 18. The DC current then flows from the closed limit switches 18 through the electrical lines 30 to the DC motors 15 which causes the DC motors 15 to rotate the worm screw 16 in a clockwise direction thereby causing the half cone covers 17 to move toward the closed position. The closing action of the two half cone covers allows less air to enter the air intake scoop 1 and decreases the rpm of shaft 7 until the desired rpm is reached. At the time the desired rpm is reached the control box 13 interrupts the flow of DC current through electrical lines 28. If the desired rpm is not reached by the time the two half cone covers are closed to 0 degrees the stop lug 25 on the stop lug guide engages the closed limit switches 18 to prevent the two half cone covers 17 from closing beyond that point by interrupting the flow of DC current through electrical lines 30 to the DC motors 15. The design of the Atmospheric/Aqua Turbine is such that it causes minimal drag on the vehicle it is installed on. It was found that air tends to form an inverted cone over the air intake scoop 1 with the more compressed air entering the air intake scoop 1. The air that is unable to enter the air intake scoop 1 is sloughed off all the way around the cone of highly compressed air, very much as if the vehicle had a needle nose instead of a gaping hole for a nose. The vacuum created at the rear of the vehicle by the speed the vehicle is traveling tends to pull air through the Atmospheric/Wind Turbine further reducing the drag on the vehicle by eliminating the vacuum at the rear of the vehicle. Although one form of this form of this invention has been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims.	The Atmospheric/Aqua Turbine is an apparatus for producing energy by allowing air or water to be metered by controls through an adjustable air or water scoop into twin turbines to produce electricity when the atmospheric/Aqua Turbine is installed on vehicle or a boat and the vehicle is travelling at 30 mph or more or in the case of the boat the boat is travelling at 8 to 10 mph or more.	5
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser generator, and, specifically, to a gas laser generator which gives a uniform and stable discharge in the discharge region. 2. Description of the Related Art Conventionally, a triaxial transverse type of gas laser generator for example, is known. In this gas laser generator the gas flows in the predetermined direction (Z-axis direction) of the discharge region, while a mirror system for an optical resonator and positive and negative discharge electrodes are respectively positioned in opposition in two directions at right angles (X-axis direction, Y-axis direction), interposing the gas flow. The mirror system is usually the so-called folded type of optical resonator for improving the gain of the optical resonator. In the optical resonator, for example, a rear folding mirror and a front folding mirror are positioned, as a pair, in opposition on both the right and left sides, interposing the gas flow. A primary mirror is positioned adjacent to the downstream side of the rear folding mirror with reference to the gas flow. In addition, an output mirror is positioned adjacent to the upstream side of the front folding mirror with reference to the gas flow. Accordingly, the optical cavity of the optical resonator, which is interposed by the mirror system, has a uniform width parallel to the gas flow, and the laser beam is uniformly amplified within the upstream gas flow and the downstream gas flow in this cavity. The discharge electrodes are positioned in multiple locations in a two-dimensional expanse on both the top and bottom sides of the optical cavity in order to uniformly excite the gas flowing in the optical cavity. The ions generated at a uniform excitation discharge of the upstream electrodes in this type of discharge device stream to the vicinity of the electrode on the downstream side, so that the resistance in the electrode gap on the downstream side declines tremendously, and the discharge deviates toward the downstream side. The downstream discharge proceeds in a localized arc, giving rise to the problem that instability could be produced in the excitation discharge. In addition, even if the arc discharge does not shift, there is also the problem that irregularities are produced in the discharge, and various inconveniences are produced in the laser output and mode pattern. Ballast resistances (stable resistances) are connected to a plurality of electrodes which are positioned in a two-dimensional expanse to provide stability of discharge. The power consumed by this ballast resistance during laser generation amounts to several KW and a large amount of heat is generated. Accordingly, the ballast resistances which are connected to each of the electrodes are housed in a cooling receptacle filled with insulating oil which cools them. The number of ballast resistances must be the same as the number of electrodes, and, for a unit provided with simmer resistances, the same number of resistances are added. In addition, there are also units in which the same number of diodes are provided. Accordingly, the wiring between the resistances and elements in the cooling receptacle becomes extremely complex, and, also, it is difficult to cool the individual ballast resistances uniformly so that the stability of the discharge is a problem area. SUMMARY OF THE INVENTION A first object of the present invention is to provide, with due consideration to the drawbacks of such conventional devices, a gas laser generator which gives a uniform and stable discharge in the discharge region. A second object of the present invention is to provide a gas laser generator in which no irregularities are produced in the discharge and which is able to produce a laser beam with a high output and suitable mode pattern. A third object of the present invention is to provide a gas laser generator in which the wiring and the like of a plurality of ballast resistances is easily performed, and in which the ballast resistances are uniformly cooled to provide a stable discharge. In order to accomplish these objects of the present invention, in the gas laser of the present invention a plurality of electrodes are positioned in the direction of flow of the gas which is the laser medium, and the electric field on the downstream side of the gas flow is smaller than the electric field on the upstream side, so that when ions are generated by the discharge, the discharge in the gas flow of the upstream side and the discharge in the gas flow of the downstream side are substantially the same. In addition, in the gas laser generator of the present invention, a plurality of ballast resistances which are connected to a plurality of electrodes are arranged on a printed board, and the ballast resistances and this printed board are immersed in a cooling receptacle filled with insulating oil. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional drawing showing an outline of the gas laser generator of the present invention. FIG. 2 is an explanatory drawing showing the concept of the discharge region and the circuit of the electrical source of the gas laser generator of the present invention. FIG. 3 is a graph showing the relationship between the ion density and the resistance between the electrodes in the discharge region. FIG. 4 is an explanatory drawing equivalent to FIG. 2, showing a second embodiment of the present invention. FIG. 5 is a sectional drawing showing enlarged details of the section indicated by the arrow V in FIG. 1. FIG. 6 is an explanatory drawing equivalent to a front elevational view of the printed board indicated by the arrow VI in FIG. 5. FIG. 7 is an explanatory drawing of the discharge circuit showing the relationship of the connections of the main resistances and the simmer resistances for reference. DETAILED DESCRIPTION OF THE INVENTION Now referring to FIG. 1, a gas laser generator 1 comprises a box-shaped frame body 3 which is open on both the left and right side sections, and a pair of semicircular tubular gas flow guide members 5 and 7 which are mounted on the frame body 3. The inside section of the frame body 3 is divided into an upper space section 9 and a lower space section 11. Inside the upper space section 9, a gas channel 13 is formed to guide the gas flow in the left to right direction in FIG. 1. A block 15 is positioned in the lower space section 11 to produce the gas G of the laser gas. A plurality of flow adjustment members 17, which guide the laser gas which is sent out from the block 15 to the gas channel 13, is positioned inside one of the gas flow guide member 5. In addition, a plurality of flow adjustment members 19, which guide the laser gas to the block 15 from the gas channel 13, and a heat exchanger 21 for cooling the laser gas, are positioned inside the other part of the gas flow guide member 7. As a result of this configuration, when the block 15 is driven rotationally in a suitable manner, the laser gas is circulated in the gas laser generator 1 and is cooled in the heat exchanger 21. In order to carry out laser oscillation, a plurality of mirrors of an optical resonator are mounted on the left and right sidewalls of the gas channel 13 along the gas flow. Specifically, a rear folding mirror 23 and a primary mirror (rear mirror) 25 are provided on the back sidewall surface of the gas channel 13 (the wall surface on the back side of the sheet in FIG. 1), with the same configuration as the usual triaxial transverse type of gas laser generator. A front folding mirror and an output mirror of the optical resonator (neither of which is shown on the drawing) are provided on the front sidewall surface (also not shown on the drawing) of the gas channel 13. Accordingly, an optical cavity 27 is formed as a region interposed between a plurality of mirrors in the gas channel 13. An anode 29, which is the positive discharge electrode for performing the discharge in the gas flow, is provided on the bottom side of the optical cavity 27. In addition, a row of upstream cathodes 31 and a row of downstream cathodes 33, which are the negative discharge electrodes, are provided on the upper side of the optical cavity 27 so that a discharge region 35 is formed between these positive and negative electrodes. The row of upstream cathodes 31 and the row of downstream cathodes 33 are formed from a plurality of needle-shaped electrodes arranged side by side in the direction perpendicular to the surface of the drawing in FIG. 1. The plurality of needle-shaped electrodes of the cathode row 31 and the cathode row 33, which will be described in detail later, are mounted in the lower section of a cooling receptacle 37 which is mounted on the top of the frame body 3. Now referring to FIG. 2, the anode 29 is positioned to cover the entire lower surface of the optical cavity 27 in order to cause uniform discharge in the gas flow passing through the optical cavity 27. As opposed to this, the row of upstream cathodes 31 (hereinafter a row of cathodes will be simply referred to as a cathode) is provided over the end of the upstream side of the anode 29 in order to provide a discharge into the gas flowing through the upstream side of the optical cavity 27. In addition, the downstream cathode 33 is provided at a distance L downstream from the upstream cathode 31 above the anode 29 in order to discharge into the gas flowing through the downstream side of the optical cavity 27. In order to perform the discharge between the anode 29 and the cathodes 31, 33, a high voltage DC power source Eo is provided in the discharge circuit. The upstream cathode 31 is connected to this DC power source Eo through a switch SW and an upstream ballast resistance R1 of a predetermined value. In addition, the downstream cathode 33 is connected to the DC power source Eo through the switch SW and a downstream ballast resistance R2 which has a larger resistance value than the upstream ballast resistance R1. The value of the resistance of the downstream ballast resistance R2 may be, for example, three times the value of the resistance of the upstream ballast resistance R1. In the configuration mentioned above, when the gas laser generator 1 is started up, the blower 15 rotates and the laser gas which is the laser medium is supplied to flow into the gas channel 13. In this way, when the gas flow is introduced into the gas channel 13, and when the discharge switch SW is turned ON, an excitation discharge is commenced between the anode 29 and the cathodes 31, 33. As a result, an excitation discharge from the upstream cathode 31 in the region as indicated by the dotted lines C1, C2 in FIG. 2 is carried out in the gas flowing into the upstream side within the optical resonator 27. Also, an excitation discharge from the downstream cathode 33 in the region as indicated by the dotted line C3 in FIG. 2 is carried out in the gas flowing into the downstream side within the optical resonator 27. Then, a stimulated emission is carried out within the laser gas which is converted to a population inversion status as a result of the excitation discharge. The rays are emitted, amplified and output as a laser beam. However, a large number of ions are produced from this discharge in the gas flow, and particularly the ions produced in the upstream cathode 31 stream to the space between the downstream cathode 33 and the anode 29. The value of the resistance between the electrodes is suddenly reduced. This status is displayed graphically in FIG. 3. The abscissa Z shows the position of the coordinates of the shows the ion density, the resistance between the electrodes, and the magnitude of the electrical field. In FIG. 3, n(Z) and Ro(Z) are respectively the ion density and the resistance between the electrodes. In addition, Z=0 and Z=L give the coordinates of the positions of the upstream cathode 31 and the downstream cathode 33 respectively. As can be understood from FIG. 3, at a position close to the downstream cathode 33 (Z≈L), compared to a position close to the upstream cathode 31 (Z≈0), the resistance between the electrodes has undergone an extreme drop and the excitation discharge status becomes unstable, so that there is a tendency for easy shift into arc discharge. However, in this embodiment of the present invention, the downstream ballast resistance R2 is set at a value which is larger in comparison to the value of the upstream ballast resistance. Accordingly, in this case, as shown in the electric field intensity curve E(Z), the strength of the electrical field close to the downstream cathode 33 is smaller in comparison with that of the upstream side. In other words, the resistances of the circuits which pass through the upstream cathode 31 and the downstream cathode 33 are almost equal, and the current in the upstream electrical field is almost equal to the current in the downstream electrical field. For this reason, the excitation discharge in the entire discharge region 35 becomes uniform. There is a uniform transition in the upstream and downstream sides of the laser gas flow to a class of higher energy, and an almost uniform population inversion distribution is obtained. Next, from this uniform population inversion distribution, when an laser beam is emitted by means of a stimulated emission, the emitted rays are amplified by the optical resonator including the primary mirror 25 and the rear folding mirror 23, and a suitable laser beam pattern at high output is output from the output mirror. Therefore, a laser beam of high output and suitable mode pattern can be easily output by means of this embodiment of the present invention. In addition, with this embodiment of the present invention, there is no worry about shifting to arc discharge because of the uniformly developed discharge in the discharge region 35. Further, the sputtering also becomes uniform and the deterioration of the electrodes becomes uniform. Further, the ratio of the resistance value of the upstream ballast resistance R1 to the resistance value of the downstream ballast resistance R2 is about 1 to 3 in the present embodiment, but is not restricted to this value. It can change according to conditions such as the components of the gas, the distance between the electrodes, the gas flow rate, the voltage between the electrodes, and the like, and a uniform discharge can be uniformly set experimentally as required. In a further embodiment of the present invention, the upstream or downstream ballast resistances R1 or R2 can be variable resistances. In this case, the resistance can be adjusted and the optimum resistance value selected in correspondence with the gas flow pressure, temperature, flow rate and the like. Accordingly, an even more stable discharge can be realized. In addition, when this variable resistance is used, the value of the electrical current flowing through the variable resistance can be detected, while the value of the resistance per se can be changed in correspondence with the value of this current. By this means, the value of the ballast resistance can be adjusted occasionally or by the minute to conform to the change of the ion concentration with time, making it possible to obtain an even smoother discharge. Further, as shown in FIG. 4, a second power source E1 may be provided from which the output voltage is lower than that from the power source Eo. The power source Eo may be connected to the upstream cathode 31 and the power source E1 to the downstream cathode 33. In this way, the same type of stability as above can be obtained along with a uniform discharge, while the values of a pair of ballast resistances R3 may be always uniform so that installation is extremely easy. In this embodiment of the present invention there are two rows of upstream and downstream cathodes, but three rows, or even more, are acceptable. In particular, in this case as well, the ballast resistance values of each row may be set to the optimum, and the values of the resistances of the circuits for the cathodes may be almost equal. Also, in this embodiment of the present invention, it is possible to apply an AC type discharge device, not just the DC type. In this case, each of the electrodes may have different impedence values. Now referring to FIG. 5, a cooling receptacle 37 for the ballast resistances which is mounted on the top of the frame body 3 is constructed in the form of a hermetically sealed box to which a lower plate 39 and a top cover 41 are secured by means of a plurality of bolts. Each electrode of the cathode rows 31 and 33 penetrates and is supported by the lower plate 39. A printed board 43 used for the upstream cathode row 31 and a printed board 45 used for the downstream cathode row 33 are positioned in the cooling receptacle 37. The lower edges of both the printed boards 43 and 45 are engaged with and maintained by a plurality of slots 39S which are formed in the upper surface of the lower plate 39. In addition, the side edges of the printed boards 43, 45 are engaged with and maintained by a plurality of slots 47S which are formed in a pair of maintaining members 47 opposingly mounted inside the cooling receptacle 37. Accordingly, when the top cover 41 is removed from the cooling receptacle 37 the installation or removal of the printed boards 43, 45 relative to the cooling receptacle can be easily performed. On the printed boards 43, 45, as shown in FIG. 5 and FIG. 6, a main resistance MR and a simmer resistance SR, equivalent to the ballast resistances R1 and R2, are systematically mounted on both surfaces, and a diode D is mounted. The number of main resistances MR, simmer resistances SR, and diodes D provided are equivalent in number to the plurality of electrodes of the cathode rows 31, 33, and, as shown in FIG. 7, are connected within the discharge circuit. In addition, a pair of terminal blocks 49 and 51 are provided on the upper edges of the printed boards 43, 45 respectively. The electrodes and resistances of the cathode rows 31, 33 are connected through the terminal blocks 49, 51 to each other and are then connected to a main power source ME and a simmer power source SE. Accordingly, the wiring for the resistances MR, SR and the diode D, and the wiring for the electrodes of the cathode rows 31, 33 can be installed with extreme ease. In addition, each of the printed boards can be exchanged as a package so that maintenance is simplified. In order to cool the resistances MR, SR and the like, the resistances MR, SR and the like are fully immersed in a cooling medium 53 within the cooling receptacle 37. The cooling medium 53 can be, for example, an insulating oil which can be suitably circulated through a heat exchanger or a cooling device and maintained at a uniform temperature. From this configuration, the resistances MR, SR, and the like are uniformly cooled by the cooling medium 53. Accordingly, any changes in the values of the resistances MR, SR, and the like are small so that the discharge is stable. The circuit shown in FIG. 7 is essentially the same as the configuration described in U.S. patent application Ser. No. 737,468 so details will be omitted here. The U.S. Patent application is incorporated herein by reference. As can be understood from the above explanation of this embodiment of the present invention, as a result of the present invention no irregularities are produced in the status of the discharge between the anode and the cathode rows, and a uniform and stable discharge is obtained in the discharge region so that a laser beam with a high output and suitable mode pattern is obtained. By means of the present invention, the wiring for a plurality of ballast resistances and the like can be performed with extreme ease, the maintenance of the ballast resistances and the like is simplified, and the ballast resistances can be uniformly cooled. Accordingly, a stable discharge is possible.	A gas laser generator comprises a frame, a gas channel through which a gas flows, a mirror for obtaining a laser beam, defining a resonant cavity, an anode electrode and at least two first and at least two second cathode electrodes arranged in the lower and the upper portions of the resonant cavity, respectively, and a power source, in which a first voltage of a first electric field between the first cathode electrodes connected to the power source through a first ballast resistance and the anode electrode and a second voltage of a second electric field between the second cathode electrodes connected to the power source through a second ballast resistance and the anode electrode are so determined that the former is smaller than the latter so that the current flowing in the first electric field may be substantially equal to the current flowing in the second electric field during the electric discharges between the electrodes.	7
FIELD OF INVENTION This invention relates to cardiac stimulators which use indicators of patient activity and body position to determine the type and intensity of cardiac stimulation. BACKGROUND OF THE INVENTION The class of medical devices known as cardiac stimulation devices can deliver and/or receive electrical energy from the cardiac tissue in order to prevent or end life debilitating and life threatening cardiac arrhythmias. Pacing delivers relatively low electrical stimulation pulses to cardiac tissue to relieve symptoms associated with a slow heart rate, an inconsistent heart rate, an ineffective heart beat, etc. Defibrillation delivers higher electrical stimulation pulses to cardiac tissue to prevent or end potentially life threatening cardiac arrhythmias such as ventricular fibrillation, ventricular tachycardia, etc. Early advances in pacing technology have led to a better quality of life and a longer life span. The development of demand pacing, in which the stimulator detects the patient's natural cardiac rhythm to prevent stimulation during times which the patient's heart naturally contracts, led to a more natural heart rate as well as a longer battery life. Another major advance was rate responsive pacing in which the stimulator determines the stimulation rate based upon the patients metabolic demand to mimic a more natural heart rate. The metabolic demand typically is indicated by the patient's activity level via a dedicated activity sensor, minute ventilation sensor, etc. The stimulator analyzes the sensor output to determine the corresponding stimulation rate. A variety of signal processing techniques have been used to process the raw activity sensor output. In one approach, the raw signals are rectified and filtered. Also, the frequency of the highest signal peaks can be monitored. Typically, the end result is a digital signal indicative of the level of sensed activity at a given time. The activity level is then applied to a transfer function that defines the pacing rate (also known as the sensor indicated rate) for each possible activity level. Attention is drawn to U.S. Pat. No. 5,074,302 to Poore, et al., entitled “Self-Adjusting Rate-Responsive Pacemaker and Method Thereof”, issued Dec. 24, 1991. This patent has a controller that relates the patient activity level signal to a corresponding stimulation rate. In addition, the controller uses the activity signal over a long time period to determine the adjustment of the corresponding stimulation rates. The activity signal can also indicate when a patient is sleeping to modify the pacing rate as set forth in U.S. Pat. No. 5,476,483 to Bornzin, et al, entitled “System and Method for Modulating the Base Rate during Sleep for a Rate-Responsive Cardiac Pacemaker”, issued Dec. 19, 1995, which is hereby incorporated by reference in its entirety. Another method of determining the stimulation rate based upon metabolic need is based upon the body position of a patient. Studies have shown that a patient being upright indicates a higher stimulation rate than for a patient lying down. An example is U.S. Pat. No. 5,354,317 to Alt, entitled “Apparatus and Method of Cardiac Pacing Responsive to Patient Position”, issued Oct. 11, 1994. In this patent, the controller monitors a motion sensor to produce a static output which represents the position of the patient, i.e., lying down or upright. This static output is used to determine whether a sleep indicated rate or an awake base rate should be used. However, this system is completely dependent upon the proper orientation of the stimulator housing during implantation for consistent and reliable results. To further improve the stimulator's ability to mimic the heart's natural rhythm, a combination of monitoring both the patient's activity level and the body position has been envisioned. U.S. Pat. No. 5,593,431 to Sheldon, entitled “Medical Service Employing Multiple DC Accelerometers for Patient Activity and Posture Sensing and Method”, issued Jan. 14, 1997, sets forth a system which monitors both parameters. This patent sets forth a cardiac stimulator which uses a multi-axis DC accelerometer system to monitor both patient position and patient activity. Unfortunately, this accelerometer also depends upon a known orientation during implant and repeated postoperative calibrations for proper operation due to shifting of the stimulator within the implant pocket. The ability to accurately determine both the patient's activity level and the patient's body posture would greatly benefit many patients by providing a more metabolically correct stimulation rate. As well, this combination of sensors could be used to determine the accuracy of other sensors such as PDI, O 2 saturation, etc. This enables the controller of the stimulator to blend the outputs of the various sensors to provide the benefit of the each individual sensor. Also, in the case of implantable cardioverter/defibrillators (ICDs), these two outputs would allow modification of the defibrillator thresholds based upon time of day and posture of the patient. Accordingly, it would be desirable to develop an implantable cardiac stimulator which adjusts the stimulation level based upon the patient activity and the patient body position via sensors that are not device implant orientation sensitive. SUMMARY OF THE INVENTION The present invention is directed towards an implantable cardiac stimulation device which determines cardiac stimulation levels based upon the patient's current body position and activity level while eliminating special implantation or calibration procedures. To determine the body position and the activity level, the stimulator monitors the output of a multi-axis DC accelerometer or a combination of sensors to include oxygen saturation, PDI, minute ventilation sensors, etc. To determine the patient's current body position, the controller establishes the output of at least two DC accelerometers during times of high activity as the patient's standing position. Lower activity levels associated with the other body orientations while lying down are also deduced in a similar manner. Then, the stimulator correlates the current outputs of the DC accelerometers with the standing position to determine the current body position and uses the previous and current body positions and the activity level (preferably calculated from the AC acceleration in the anterior-posterior axis, the axis which has the best correlation with the patient activity), to determine the instantaneous stimulation needed. Because this stimulator depends upon the combination of activity signals and position signals from the multi-axis accelerometer, this device is not dependent upon a predetermined implant orientation or repeated calibration of the accelerometer after implant. If the device should shift within the patient after implant, the controller will accommodate this change during the patient's next high activity period. As such, this device monitors the activity and position signals from the multi-axis accelerometer to determine the indicated activity level of the patient and the current body position and then determines the type and intensity of cardiac stimulation the patient needs. In a further aspect of a preferred embodiment of the present invention, the calculated standing position is monitored to detect changes that may indicate the presence of twiddler's syndrome. BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects, features, and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: FIG. 1 is a block diagram of an implantable stimulation device as set forth in the present invention; FIG. 2 is an example of an exemplary three-axis accelerometer within a stimulator housing, suitable for use with the present invention; FIG. 3 sets forth a two-dimensional cluster plot as outputted by the accelerometer; FIG. 4 sets forth a flow chart for a method of determining the variables (x c , y c ) in accordance with the present invention; FIGS. 5A-5B set forth a flow chart for a method for determining the current position of the patient in accordance with the present invention; FIG. 6 sets forth a transfer function for determining the activity indicated rate; FIG. 7 sets forth a transfer function for determining the circadian base rate; FIG. 8 sets forth a normal heart rate response when a patient stands after a prolonged period of lying down; FIG. 9 sets forth a time table of an example of an orthostatic compensation stimulation regime; FIG. 10 sets forth a flow chart for a method of determining an instantaneous stimulation rate in accordance with the present invention; and FIG. 11 set forth a flow chart of an exemplary supplement to the flow chart of FIG. 4 for detecting twiddler's syndrome. DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, an implantable cardiac stimulation device in accordance with the present invention is shown as a dual sensor rate responsive pacemaker 10 . It is well within the scope of this invention to operate this stimulation device in a demand mode as is well known within the art. Also, the principles of this invention would be easily applied to defibrillation theory by one of ordinary skill in the art. While the preferred embodiment is directed towards a stimulation device which uses a multi-axis (two or more axis) accelerometer for determining the pacing rate and stimulation intensity, it is well within the scope of this invention to apply the principles of this invention for use with other physiologic sensors that also indicate patient position and activity. FIG. 1 sets forth a simplified block diagram of the stimulation device 10 . The stimulation device 10 is coupled to a heart 5 by way of two leads 12 , 14 . The first lead 12 has at least one electrode 18 in contact with the atrium of the heart 5 , and the second lead has at least one electrode 20 in contact with the ventricle of the heart 5 . The leads 12 , 14 are electrically and physically connected to the stimulation device 10 through a connector 16 which forms an integral part of the housing (not shown) in which the circuits of the stimulation device 10 are housed. The connector 16 electrically protects circuits within the stimulation device 10 via protection network 17 from excessive shocks or voltages that could appear on electrodes 18 , 20 in the event of contact with a high voltage signal, e.g., from a defibrillator shock. The leads 12 , 14 carry the stimulating pulses to the electrodes 18 , 20 from the atrial pulse generator (A-PG) 22 and a ventricular pulse generator (V-PG) 24 , respectively. Further, the electrical signals from the atrium are carried from the electrode 18 through the lead 12 to the input terminal of the atrial channel sense amplifier (P-AMP) 26 . The electrical signals from the ventricle are carried from the electrode 20 through the lead 14 to the input terminal of the ventricular channel sense amplifier (R-AMP) 28 . Similarly, electrical signals from both the atrium and the ventricle are applied to the inputs of the IEGM (intracardiac electrogram) amplifier 30 . The stimulation device 10 detects an evoked response from the heart to an applied stimulus, allowing the detection of the capture with a suitable broad bandpass filter. The IEGM amplifier 30 is also used during the transmission to an external programmer 60 . The stimulation device 10 uses a controller (microprocessor control and timing circuits) 32 that typically includes a microprocessor to carry out the control and timing functions. The controller 32 receives output signals from the atrial amplifier 26 , the ventricular amplifier 28 , and the IEGM amplifier 30 over the signal lines 34 , 36 , 38 , respectively. The controller 32 then generates trigger signals that are sent to the atrial pulse generator 22 and the ventricular pulse generator 24 over the signal lines 40 , 42 , respectively. The stimulation device 10 also includes a memory 48 that is coupled-to the controller 32 over a suitable data/address bus 50 . This memory 48 stores customized control parameters for the stimulation device's operation for each individual patient. Further, the data sensed by the IEGM amplifier 30 may be stored in the memory 48 for later retrieval and analysis. A clock circuit 52 directs appropriate clock signal(s) to the controller 32 as well as any other circuits throughout the stimulation device 10 , e.g., to the memory 48 by a clock bus 54 . The stimulation device 10 also has a telemetry communications circuit 56 which is connected to the controller 32 by way of a suitable command/data bus 58 . In turn, the telemetry communications circuit 56 is selectively coupled to the external programmer 60 by an appropriate communications link 62 , such as an electromagnetic link. Through the external programmer 60 and the communications link 62 , desired commands may be sent to the controller 32 . Other data measured within or by the stimulation device 10 such as IEGM data, etc., may be sorted and uploaded to the external programmer 60 . The stimulation device 10 derives its electrical power from a battery 64 (or other appropriate power source) which provides all operating power to all the circuits of the stimulation device 10 via a POWER signal line 66 . The stimulation device 10 also includes a sensor 68 that is connected to the controller 32 over a suitable connection line 72 . In the preferred embodiment, this sensor detects patient activity and indicates the patient's position via a multi-axis (i.e., two or more axis) DC accelerometer. However, any appropriate sensor or combination of sensors which indicate levels of patient activity and indicate the patient's position could be used. Other such sensors, such as a minute ventilation sensor, blood pressure sensor, PDI sensor, etc., can be used to in lieu of or supplemental to the activity signal from the accelerometer. In the case of some of these alternative sensors, the sensor could be placed on the lead 14 as shown by an alternative sensor 69 . The above described stimulation device 10 generally operates in a conventional manner to provide pacing pulses at a rate that comfortably meets the patient's metabolic demands. In a typical case, the controller 32 uses the signals generated by the sensor 68 (or other alternative sensors 69 ) to determine both the activity level and the body position of the patient, both indicators of metabolic need. Many methods of determining the activity level of the patient are well known within the art. Attention is drawn to the '483 patent, which is hereby incorporated by reference. To regulate the pacing rate, the controller 32 provides a trigger signal to the atrial pulse generator 22 and/or the ventricular pulse generator 24 . The timing of this signal (to a large extent) is determined by the activity level of the patient, body position, and the individualized control parameters. In embodiments of the present invention, each multi-axis DC accelerometer consists of at least two DC accelerometers (hereafter known as DC sensors), preferably mounted essentially orthogonal to each other. FIG. 2 sets forth an exemplary embodiment with three DC sensors attached to the inside of a stimulator housing 205 . In the example of FIG. 2, these three DC sensors are labeled superior-inferior 210 , anterior-posterior 215 , and lateral-medial 220 , respectively. Each DC sensor can also generate the activity level of the patient, i.e., AC acceleration. Each of the DC sensors 210 , 215 , 220 is preferably a surface micromachined integrated circuit with signal conditioning as is well known in the art. Employing surface micromachining, a set of movable capacitor plates are formed extending in a pattern from a shaped polysilicon proof mass suspended by tethers with respect to a further set of fixed polysilicon capacitor plates. The proof mass has a sensitive axis along which a force between 0 G and +50 G effects the physical movement of the proof mass and a change in the measured capacitance between the fixed and moveable plates. The measured capacitance is transformed by the on-chip signal conditioning circuits into a low voltage signal. Further information regarding the physical construction of the DC sensors can be found in the '431 patent, hereby incorporated by reference in its entirety. However, many other types of accelerometers are commercially available, and it would be obvious to one of ordinary skill in the art to use other types of accelerometers in place of the above described multi-axis DC accelerometer. While, three or more DC sensors are preferred, systems of the present invention can be formed from two DC sensors, as described further below. To determine both the activity level and the body position of the patient, the controller 32 monitors the output of each of the DC sensors. Preferably using standard analog to digital conversion techniques, the output of each of the DC sensors is filtered to separate an AC signal component (representing the activity level) and a DC signal component (representing the body position). Then, the two resultant signals are further processed to determine two corresponding digital outputs which represent the instantaneous signal level of each signal. The resulting activity digital signals are then further processed to determine the activity level of the patient by methods well known within the art. One example is contained in the '302 patent, hereby incorporated by reference in its entirety. The resulting two position signals are processed to determine the indicated body position as discussed below. Knowing the activity level, the activity variance measurements can be determined. Activity variance is the long term variance in the patient's activity as derived by the controller 32 and gives a further indication of the patient's activity. For example, a high variance measurement indicates the patient has been quite active and a low variance measurement indicates that a patient has been resting or sleeping. Preferably, these activity and activity variance signals are calculated from the accelerometer output in the anterior-posterior axis which has the best correlation with the patient physical activity. For further information regarding the determination of the activity variance, attention is drawn to the '483 patent, hereby incorporated by reference in its entirety. Once the activity level of the patient is determined, the controller 32 then determines the instantaneous position of the stimulator housing 205 within the patient. By using the digital outputs of the lateral-medial 220 and superior-inferior 210 DC sensors shown in FIG. 2, a two dimensional plot can be created to show the clusters in the different graph positions which represent different body postures of the patient. When the stimulator housing 205 shifts within the patient's body, the clusters on the two dimensional plot will rotate correspondingly, but the relative positions of the clusters will not change. The graph of FIG. 3 is defined as follows: x is the current indicated position in the lateral-medial axis, y is the current indicated position in the superior-inferior axis, and (x c , y c ) represents the average of the digital outputs that have correlated to the patient being oriented in a standing position. To determine the orientation of the accelerometer indicating that the patient is standing, attention is drawn to FIG. 4 which shows an exemplary flowchart. First, at step 405 , the activity level (LastAV) and the activity variance (Act_Var) measurements are monitored as well as the current digital outputs from the DC sensors, e.g., 210 , 220 . The digital outputs are used to determine an initial (x, y) value. Then, at step 410 , both the activity level (LastAV) and the activity variance (Act_Var) measurements are compared to corresponding standing thresholds, respectively Activity Standing Threshold and AV Standing Threshold. If both variables are above their corresponding standing thresholds, the controller 32 continues to step 415 , where the controller 32 increments a counter and adds the current digital outputs indicative of (x, y) to an accumulated (x, y) value. Then, at step 420 , the controller 32 determines if the counter has reached its threshold value (e.g., 120 counts). If the controller 32 has not reached its threshold value, the controller 32 returns to step 405 . If the controller 32 has reached its threshold value, the controller 32 continues to step 425 where the controller 32 determines (x c , y c ) by averaging the accumulated (x, y) value over the counter period. Afterwards, in step 435 , the controller 32 resets the counter to zero to prepare for another update. The controller then returns to step 405 . As shown in step 430 , if one of these variables is not above the corresponding standing threshold, then the counter and the accumulated (x, y) values are reset to 0, and the controller 32 returns to step 405 . Once the controller 32 has determined what position (x c , y c ) corresponds to the patient standing, the controller 32 then determines the current body position. FIGS. 5A-5B sets forth an exemplary flow chart to determine the current body position of the patient. To begin the process, the controller 32 sets the current position code (Current Position) equal to 1. The current position code is a binary code of 1 or 0 which indicates whether the patient is standing (1) or lying down (0). Additionally, the controller 32 sets the time the patient has been at rest, T REST , equal to 0, and stores T REST into memory 48 at step 501 . At step 505 , the controller 32 reads the current position code and the activity level (LastAV) out of the memory 48 . The activity level (LastAV) is determined from the digital output of the AC portion of the DC sensor output as discussed above. The controller 32 then determines the projection value (P). The projection value (P) is a numerical indication of the correlation between the current body position (x, y) to the determined standing position (x c , y c ) as calculated below: P = ( x * x c + y * y c ) ( x c 2 + y c 2 ) If the projection value (P) indicates a correlation value of greater than a standing threshold, e.g., at least 0.65, the current body position (x, y) is considered to be standing. For example, using the values referenced in the discussion of FIG. 3, a projection value (P) of 0.968 is calculated. Accordingly, the current (x, y) value shown in the example of FIG. 3 would be considered to correspond to the patient being in a standing position. Once the controller 32 has determined these three values (i.e., T REST , activity level (LastAV), and the projection value (P)), it proceeds to step 510 . At step 510 , the controller 32 determines if the current position code indicates that the patient was standing. If the current position code=1, the controller 32 proceeds to step 515 . Then, at step 515 , the controller 32 determines if the current projection value (P) is less than a standing threshold (Standing_Threshold), e.g., 0.65, and if the activity level (LastAV) is below an activity threshold (Act_Avg). If either of these conditions is not true at step 515 , the controller 32 proceeds to step 520 where the controller 32 stores the current position code as the last position code (Last Position) and sets the current position code equal to 1, indicating that the patient is still standing. The controller 32 then returns to step 505 . If both of these conditions are true at step 515 , the controller 32 proceeds to step 525 where the controller 32 compares the current value of T REST with a resting threshold (Rest_Enough). If T REST is not equal to a resting threshold (Rest_Enough), then T REST is incremented at step 530 . At step 535 , the controller 32 stores the current position code as the last position code and sets the current position code equal to 1, indicating that the patient is standing since the patient has not been at rest for a sufficient period of time. The controller 32 then returns to step 505 . If T REST is equal to the resting threshold at step 525 , then, at step 540 , the last position code is set equal to the current position code and the current position code is set to 0, indicating that the patient is no longer standing. Then, the controller 32 returns to step 505 . Returning to step 510 , if the current position code was not equal to 1, the controller 32 proceeds to step 545 , where the controller 32 determines if the projection value (P) is greater than the standing threshold (e.g., 0.65) and if the activity level (LastAV) is greater than the activity threshold (Act_Avg), e.g., indicating that the patient is exercising. If these conditions are both true at step 545 , the controller 32 proceeds to step 550 where T REST is set to 0. The controller 32 then proceeds to step 555 where the last position code is set equal to the current position code and the current position code is set to 1 to indicate that the patient is now standing. The controller 32 then returns to step 505 . If either condition is not met at step 545 , then the controller 32 proceeds to step 560 where the last position code is set equal to the current position code and the current position code is set to 0 to indicate that the patient is still at rest. The controller 32 then returns to step 505 . While a two dimensional calculation has been described, one of ordinary skill would appreciate that this calculation could be expanded to a three dimensional case with the use of three DC sensors, e.g., 220 , 210 , 215 of FIG. 2, respectively indicating the (x, y, z) positions of the patient's body. In such a case the projection value (P) would be calculated as: P = ( x * x c + y * y c + z * z c ) ( x c 2 + y c 2 + z c 2 ) One application of this method of determining body position is in orthostatic compensation pacing. Patients who suffer from long term diabetes tend to develop neuropathy from the long term exposure of their nerves to excessive blood sugar levels. This condition erodes the body's ability to adequately control the heart rate. In particular, this condition renders the patient unable to compensate for the dramatic drop in blood pressure upon standing after sitting or lying down for an extended period of time due to an inability of the body to increase the heart rate and constrict the system resistance and capacitance of its blood vessels. To overcome this condition, the controller 32 compensates for the change in the patient position by triggering an orthostatic compensation rate when the body position, the activity level signal, and the activity variance indicate a sudden change in the patient's activity after a prolonged period of inactivity. This pacing regime is blended into a traditional transfer function indicated by the activity level and activity variance measurements as discussed below. In FIG. 6, the activity indicated rate (AIR) is illustrated. The transfer function is used by the controller 32 to correlate the activity level measurements shown along the horizontal axis to the activity indicated pacing rates shown along the vertical axis. The controller 32 then triggers the appropriate pulse generator 22 , 24 at the activity indicated rate. It should be noted that an appropriate transfer function can be used based upon individual need. In addition, different modes of pacing (e.g., DDD, VVI, etc.) can be accommodated by this method. Two activity levels are noted on the horizontal axis of the transfer function: a low activity threshold 602 and a high activity threshold 604 . For activity level measurements above the high activity threshold 604 , the pacing rate is maintained at a maximum pacing rate 606 as determined by the physician. For activity level measurements between the low activity threshold 602 and the high activity threshold 606 , the activity indicated pacing rate varies according to a programmed transfer function 608 . In this case, the activity indicated pacing rate varies linearly between a base rate 610 and a maximum pacing rate 606 . However, this transition can be programmed to meet the patient's need by the physician in many different ways as is well known in the art or periodically adjusted by the controller 32 as set forth in U.S. Pat. No. 5,514,162 to Bornzin, et al., entitled “System and Method for Automatically Determining the Slope of a Transfer Function for a Rate-Responsive Cardiac Pacemaker”, issued May 7, 1996, hereby incorporated by reference. The circadian base rate (CBR), illustrated in FIG. 7, is established by monitoring the activity variance measurements (also known as the long term variance in activity) as described more fully in the '483 patent, hereby incorporated by reference in its entirety. The transfer function is used by the control system to correlate the activity variance level shown along the horizontal axis to the CBR shown along the vertical axis. The controller 32 then triggers the appropriate pulse generator 22 , 24 at the activity indicated rate. Preferably, an appropriate transfer function can be used based upon individual need. In addition, different modes of pacing, i.e., DDD, VVI, etc.) can be accommodated by this method. Two activity variance levels are noted on the horizontal axis of the transfer function: a low activity variance threshold 652 and a high activity variance threshold 654 . For activity variance level measurements above the high activity variance threshold 654 , the CBR is maintained at a maximum pacing rate 656 as determined by the physician. For activity level measurements between the low activity variance threshold 652 and the high activity variance threshold 654 , the CBR varies according to a programmed transfer function 658 . In this case, the CBR varies linearly between a minimum CBR 660 and a maximum CBR 656 . For activity variance level measurements below the low activity variance threshold 652 , the controller 32 sets the CBR as defined by the minimum CBR 660 . A patient's activity level is monitored and activity variance measurements are calculated to determine when and how long a patient typically rests or sleeps. These two terms define a stimulation rate which is below the programmed base rate such that the controller 32 triggers pacing pulses at a lower pacing rate during sleep. This lower pacing rate more closely mimics the natural cardiac rhythm exhibited during rest or sleep. FIG. 8 sets forth one sample of an experimentally observed orthostatic response of a normal healthy person. Upon standing after a prolonged period of sitting or lying down, the normal sinus rate quickly increases to a peak 702 of approximately 80 to 120 bpm within 10 seconds. Then, the rate slowly decreases to the base rate, typically 70 bpm, in about 10 to 20 seconds. FIG. 9 shows an exemplary orthostatic compensation pacing regime that can be delivered to the pacemaker patient upon the detection of a posture change from standing up to lying down. The controller 32 increases the orthostatic compensation rate (OSCR) from a base rate 800 to a peak 802 in seven cardiac cycles. After the OSCR reaches the maximum, it is maintained at the maximum level for another 7 cardiac cycles. The rate then slowly decreases down to the base rate in about 12 cardiac cycles. Preferably, the specific orthostatic compensation pacing regime, including the maximum OSCR, the slopes and the duration, can be varied and is typically determined by the physician. As such, the regime set forth in FIG. 9 is only an example. FIG. 10 sets forth an exemplary flow chart describing how the controller 32 determines the immediate pacing rate. Upon initiation at step 900 , the controller 32 sets the value of the T OSC counter equal to 0. The T OSC counter represents the cycle pointer of the orthostatic compensation pacing regime as set forth on the x-axis of FIG. 9 . The controller 32 then proceeds to step 905 where the controller 32 determines if the T OSC counter is equal to 0. If this condition is not true at step 905 , then the controller 32 is already within the orthostatic compensation (OSC) pacing regime and proceeds to step 910 . The controller 32 then sets the stimulation rate (SIR) to be the maximum of an activity indicated rate (AIR), a circadian base rate (CBR), or an orthostatic compensation rate (OSCR(T OSC )). Preferably, this function OSCR(T OSC ) is performed as a look-up function of data within an orthostatic compensation table 916 within the memory 48 . The controller 32 then proceeds to step 915 , where the controller 32 increments the T OSC counter. If at step 920 , the T OSC counter has reached the end of the orthostatic compensation table 916 , the controller 32 resets the T OSC counter to 0 at step 925 because the orthostatic compensation regime has been completed. The controller 32 then returns to step 905 to continue the orthostatic compensation regime. If at step 920 , the T OSC counter has not reached the end of the orthostatic compensation table, then the controller 32 proceeds directly to step 905 . Returning to step 905 , if the T OSC counter is equal to 0, the controller 32 proceeds to step 930 . This condition represents that the patient is not currently receiving the orthostatic compensation regime. The controller 32 then reads the last position and the current position codes from the memory 48 . The controller 32 then, at step 935 , determines if the last position code is equal to 0 and if the current position code is equal to 1. If these conditions are not met at step 930 , then, at step 940 , the controller 32 sets the stimulation rate (SIR) to the maximum of the activity indicated rate (AIR) and the circadian base rate (CBR) as discussed above. If these conditions are met at step 935 , then the patient has just stood up after a period of lying down. In this case, the controller 32 triggers the orthostatic compensation regime. To this end, the controller 32 proceeds to step 945 where the controller 32 sets the T OSC counter to 1 and sets the stimulation rate (SIR) to be equal to the maximum of the activity indicated rate (AIR), the circadian base rate (CBR), and the orthostatic compensation rate (OSCR(T OSC )) as set forth above. The controller 32 then returns to step 905 where the orthostatic compensation routine will continue through step 910 as previously described. Once the controller 32 determines the instantaneous stimulation rate (SIR), the controller 32 returns to the posture detection mode (see FIGS. 4 and 5) to determine the new current patient position. Once the controller 32 updates the last position code with the current position code and determines the current patient position, the controller 32 then returns to update the instantaneous stimulation rate (SIR). Also, any time the controller 32 detects that the activity level exceeds the standing threshold, the controller 32 returns to update the standing center (x c , y c ) Other applications of this invention include adjustment of stimulation parameters such as the AV delay, the PVARP, the stimulation level, and timing. For example, the AV delay could be shortened when the patient is known to be standing. Also, the base rate can be adjusted for a patient being in a standing position versus lying down. Also, knowing the position and the activity level of the patient can allow the triggering of monitoring functions under known conditions. For instance, when a patient is reliably known to be sleeping (i.e., inactive and lying down), monitoring functions such as heart sounds, respirations, intrinsic heart sounds, etc., can be measured for long-term monitoring of cardiovascular function. As an additional feature, embodiments of the present invention may include the capability to detect twiddler's syndrome. Twiddler's syndrome refers to the condition where an implanted cardiac stimulation device sits loosely in the pocket in the patient's chest. Consequently, the cardiac stimulation device may rotate in the pocket due to purposeful or inadvertent activity by the patient, eventually causing lead dislodgment or fracture. By comparing the currently calculated standing position (x c , y c ) to an initial calculation of the standing position (i.e., its implantation position (x ci , y ci )), embodiments of the present invention can recognize movements of the cardiac stimulation device that may correspond to twiddler's syndrome. FIG. 11 shows a flow chart of an exemplary supplement to the flow chart of FIG. 4 that may be used for detecting twiddler's syndrome. This supplement is placed following block 425 of FIG. 4 where the current standing position value (x c , y c ) is calculated. In step 950 , it is determined whether this is the first calculation of (x c , y c ). If this is the first calculation, an initial, e.g., an implantation, standing position value (x ci , y ci ) is stored in memory 48 and the process continues in step 435 . Following subsequent calculations of the standing position, the process continues in step 954 where the currently calculated standing position (x c , y c ) is compared to the initial calculated standing position (x ci , y ci ) This calculation may be done by a linear comparison by separately determining the amount of change in the x and y components of the standing position value. Then, in step 956 these x and y values are compared to a twiddler's threshold value to determine if the change in the standing position may indicate twiddler's syndrome. Preferably, a calculation may be performed as shown below: P t = ( x c * x ci + y c * y ci ) ( x ci 2 + y ci 2 ) to determine the correlation between the initial standing position value and the current standing position value. (Of course, while a two axes calculation is shown, the calculation can be expanded as previously described for a three axes embodiment.) A value of less than a predetermined Twiddler's Threshold value, e.g., 0.85, may indicate twiddler's syndrome. Accordingly, the process continues in step 958 where a Twiddler's Flag is set. The process then continues at step 435 . The status of the Twiddler's Flag may be sent to the external programmer 60 during a follow up visit of the patient to the physician. Preferably, the setting of the Twiddler's Flag can alert a physician of the potential prescience of twiddler's syndrome before damage to the lead has occurred. The flow chart of FIG. 11 is only an exemplary method of monitoring for twiddler's syndrome. One of ordinary skill in the art would recognize that other methods could be used to monitor for trends in the calculated standing position. For example, one could monitor for changes in the calculated standing position between calculations or groups of calculations without actually storing the first post implantation value. All such methods are considered to be within the scope of the present invention. Although the invention has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the application of the principles of the invention. For instance, this method can also be used to alter the defibrillation parameters in an implantable cardioverter/defibrillator unit. Accordingly, the embodiments described in particular should be considered exemplary, not limiting, with respect to the following claims.	An implantable cardiac stimulation device which determines stimulation based upon the patient's body position and activity level while eliminating special implantation or calibration procedures. To eliminate such special implantation and calibration procedures, the stimulation device correlates the patient's body position using a multi-axis DC accelerometer or other sensor during times of high activity and determines a patient's standing position value. During other times, the stimulation device compares the signals from the accelerometer to the standing position value to determine the patient's current body position. Based upon the current body position and the activity level, the stimulation device determines the necessary stimulation to deliver to the patient.	0
FIELD OF THE DISCLOSURE Embodiments of the present disclosure are related to compositions and methods for inhibiting the growth of potato pathogens under post-harvest storage conditions. BACKGROUND OF THE DISCLOSURE Currently, pesticides are the primary means of controlling postharvest diseases of fruits and vegetables. However, synthetic pesticides have considerable side effects. As well as the phytotoxic and off-odour effects of some prevalent pesticides, high and acute residual toxicity, and long degradation periods, have limited their use. As a result, there has been considerable interest in the use of natural alternatives as food additives to prevent bacterial or fungal growth and to extend the shelf life of foods. Many naturally occurring compounds such as phenols, aldehydes, and organic acids, present in spices and herb extracts, are known to have antimicrobial activity. Postharvest potato pathogens such as Erwinia carotovora, Colletotrichum coccodes and Helminthosporium solani have become economically important in the table stock market because disease affected potatoes are rejected by processors due to higher tuber health standards demanded by supermarkets and consumers. At present, management of these diseases relies exclusively on frequent applications of foliar fungicides, rather than protecting tubers directly. No effective fungicides (as resistance to thiabendazole is common) are registered for direct application to tubers for control of these important pathogens in storage. Throughout this description, including the foregoing description of related art, any and all publicly available documents described herein, including any and all U.S. patents, are specifically incorporated by reference herein in their entirety. The foregoing description of related art is not intended in any way as an admission that any of the documents described therein, including pending United States patent applications, are prior art to embodiments of the present disclosure. Moreover, the description herein of any disadvantages associated with the described products, methods, and/or apparatus, is not intended to limit the disclosed embodiments. Indeed, embodiments of the present disclosure may include certain features of the described products, methods, and/or apparatus without suffering from their described disadvantages. SUMMARY OF THE DISCLOSURE The present application provides compositions comprising one or more naturally occurring volatiles for use in the prevention, inhibition, or control of postharvest potato pathogens. According to some embodiments, the one or more naturally occurring volatiles may be selected from the group consisting of acetaldehyde, 2-(E)-hexenal, or combinations thereof. In some embodiments, the one or more naturally occurring volatiles may be encapsulated (e.g., micro-encapsulated) in a cyclodextrin (e.g., β-cyclodextrin). See U.S. Publication No. 2009/0060860 and 2007/0207981, incorporated herein by reference in their entireties. The concentration of volatile is between about 0.5 to 50 μL/L (e.g., about 0.5 to 50 μL/L, about 0.5 to 40 μL/L, about 0.5 to 30 μL/L, about 0.5 to 20 μL/L, about 0.5 to 10 μL/L, about 0.5 to 5 μL/L, about 0.5 to 4 μL/L, about 0.5 to 3 μL/L, about 0.5 to 2 μL/L, about 5 to 50 μL/L, about 5 to 40 μL/L, about 5 to 30 μL/L, about 1 to 10 μL/L, about 2 to 10 μL/L, about 3 to 10 μL/L, about 5 to 20 μL/L, or about 5 to 10 μL/L). According to some embodiments, methods are provided for treating harvested potatoes with one or more naturally occurring volatiles. In some embodiments, methods are provided for treating harvested, unwashed potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for inhibiting the growth of postharvest potato pathogens on stored harvested potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for inhibiting the growth of postharvest potato pathogens on stored harvested potatoes comprising treating harvested, stored, and/or shipped potatoes with one or more naturally occurring volatiles. In some embodiments, the pathogens may be Erwinia carotovora, Colletotrichum coccodes and Helminthosporium solani. According to some embodiments, methods are provided for controlling or preventing postharvest disease in stored harvested potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for controlling or preventing postharvest disease in harvested, stored, and/or shipped potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for extending the storability and shelf-life of potatoes comprising treating harvested, stored, and/or shipped potatoes with one or more naturally occurring volatiles. According to some embodiments, there is provided a polymeric plastic container or packaging containing one or more naturally occurring volatiles for use in the storage and/or shipping of harvested potatoes. The volatile may be contained in a controlled release mechanism. In some embodiments, the concentration of volatile is between about 0.5 to 50 μL/L (e.g., about 0.5 to 50 μL/L, about 0.5 to 40 μL/L, about 0.5 to 30 μL/L, about 0.5 to 20 μL/L, about 0.5 to 10 μL/L, about 0.5 to 5 μL/L, about 0.5 to 4 μL/L, about 0.5 to 3 μL/L, about 0.5 to 2 μL/L, about 5 to 50 μL/L, about 5 to 40 μL/L, about 5 to 30 μL/L, about 1 to 10 μL/L, about 2 to 10 μL/L, about 3 to 10 μL/L, about 5 to 20 μL/L, or about 5 to 10 μL/L). In some embodiments, the size of the container may be between about 0.1 to 1 L. In some embodiments, the size of the container may be between about 1 to 1,000,000 L (e.g., about 1,000 to 10,000 L; about 10 to 1,000 L; about 50 to 1,000 L; about 100 to 1,000 L; about 10 to 1,000 L; or about 500 to 1,000 L; about 10,000 to 100,000 L; about 100,000 to 1,000,000 L; or about 1 to 10 L). According to some embodiments, methods are provided for storing harvested potatoes in the presence of one or more naturally occurring volatiles. According to some embodiments, methods are provided for storing harvested potatoes in the presence 2-(E)-hexenal. The concentration of volatile may be between about 0.5 to 50 μL/L (e.g., about 0.5 to 50 μL/L, about 0.5 to 40 μL/L, about 0.5 to 30 μL/L, about 0.5 to 20 μL/L, about 0.5 to 10 μL/L, about 0.5 to 5 μL/L, about 0.5 to 4 μL/L, about 0.5 to 3 μL/L, about 0.5 to 2 μL/L, about 5 to 50 μL/L, about 5 to 40 μL/L, about 5 to 30 μL/L, about 1 to 10 μL/L, about 2 to 10 μL/L, about 3 to 10 μL/L, about 5 to 20 μL/L, or about 5 to 10 μL/L). In some embodiments, the size of the container may be between about 0.1 to 1 L. In some embodiments, potatoes may be stored in a room or container may be between about 1 to 1,000,000 L, or more (e.g., about 1,000 to 10,000 L; about 10 to 1,000 L; about 50 to 1,000 L; about 100 to 1,000 L; about 10 to 1,000 L; or about 500 to 1,000 L; about 10,000 to 100,000 L; about 100,000 to 1,000,000 L; or about 1 to 10 L). DETAILED DESCRIPTION OF THE INVENTION For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It should nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. According to some embodiments, methods are provided for treating harvested potatoes with one or more naturally occurring volatiles. In some embodiments, methods are provided for treating harvested, unwashed potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for inhibiting the growth of postharvest potato pathogens on stored harvested potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for inhibiting the growth of postharvest potato pathogens on stored harvested potatoes comprising treating harvested, stored, and/or shipped potatoes with one or more naturally occurring volatiles. In some embodiments, the pathogens may be Erwinia carotovora, Colletotrichum coccodes and Helminthosporium solani. According to some embodiments, methods are provided for controlling or preventing postharvest disease in stored harvested potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles. According to some embodiments, methods are provided for controlling or preventing postharvest disease in harvested, stored, and/or shipped potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles. Postharvest pathogens and diseases include the following: Disease Causal Agent Symptoms Dry rot Fusarium spp. brown, firm, sunken flesh; sunken and wrinkled surfaces with blue or white protuberances Soft rot Erwinia carotovora soft, water cavities in flesh, foul smell; in non-russeted varieties, shallow, round lesions around lenticels Leak Pythium oozing tubers; well defined areas between healthy and diseased flesh; pink then black flesh with granular, mushy rot Late Phytophthora small, shrunken, dark spots in flesh; foul smell blight infestans Ring rot Cornybacterium vascular ring yellow sepedonicum Pink rot Phytophthora erythroseptic Silver Helminthosporium The appearance of silver scurf lesions often changes Scurf solani during the storage period. Severe browning of the surface layers of tubers may occur, followed by sloughing-off of the outer layers of the periderm, so that the tuber is protected only by the inner periderm. Lesions have definite margins and are circular, but individual lesions may coalesce as the disease progresses. The silvery appearance of older lesions, for which the disease is named, is most obvious when the tubers are wet and results from air pockets in dead periderm cells. After some time in storage, the surface of the infected tubers may become shriveled and wrinkled due to excessive water loss from the silver scurf lesions. According to some embodiments, methods are provided for extend the storability and shelf-life of potatoes comprising treating harvested, stored, and/or shipped potatoes with one or more naturally occurring volatiles. According to some embodiments, there is provided methods of treating harvested potatoes with one or more naturally occurring volatiles, wherein the one or more naturally occurring volatile is 2-(E)-hexenal. According to some embodiments, there is provided methods for inhibiting the growth of postharvest potato pathogens on stored harvested potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles, wherein the one or more naturally occurring volatile is 2-(E)-hexenal. In some embodiments, the pathogen is Erwinia carotovora, Colletotrichum coccodes and/or Helminthosporium solani. According to some embodiments, there is provided methods of controlling or preventing postharvest disease in stored harvested potatoes comprising treating harvested potatoes with one or more naturally occurring volatiles, wherein the one or more naturally occurring volatile is 2-(E)-hexenal. In some embodiments, the disease is selected from the group consisting of dry rot, soft rot, leak, late blight, ring rot, pink rot, and silver scurf. According to some embodiments, there is provided methods of extending the storability and shelf-life of potatoes comprising treating harvested, stored, and/or shipped potatoes with one or more naturally occurring volatiles, wherein the one or more naturally occurring volatile is 2-(E)-hexenal. According to some embodiments, there is provided methods of storing harvested potatoes comprising storing harvested potatoes in the presence of one or more naturally occurring volatiles, wherein the one or more naturally occurring volatile is 2-(E)-hexenal. In some embodiments, the concentration of the one or more naturally occurring volatile is between about 0.5 to 50 μL/L. In some embodiments, the naturally occurring volatile is contained in a controlled release mechanism. In some embodiments, the naturally occurring volatile is encapsulated. In some embodiments, the naturally occurring volatile is encapsulated in a cyclodextrin. In some embodiments, the naturally occurring volatile is encapsulated in a β-cyclodextrin. According to some embodiments, there is provided a polymeric plastic container or packaging containing harvested potatoes and one or more naturally occurring volatiles, wherein the one or more naturally occurring volatile is 2-(E)-hexenal. In some embodiments, the concentration of the one or more naturally occurring volatile is between about 0.5 to 50 μL/L. In some embodiments, the naturally occurring volatile is contained in a controlled release mechanism. In some embodiments, the naturally occurring volatile is encapsulated. In some embodiments, the naturally occurring volatile is encapsulated in a cyclodextrin. In some embodiments, the naturally occurring volatile is encapsulated in a β-cyclodextrin. STORAGE Before storage, potatoes should be culled and cured. Cull and discard any damaged, diseased or frozen tubers. Curing potatoes heals the skin, making it less susceptible to damage and disease. Cure potatoes by exposing them to temperatures between 50 and 60 degrees F. and 95% relative humidity for 10 to 14 days. Potatoes may be either stored in refrigerated warehouses or non refrigerated bulk bins up to 20 feet deep. In the bulk bins, air should be forced from the floor through corrugated metal ducts up through the pile. This ensures good distribution of cool, humid air, which decreases shrinkage, sprouting, and decay. For table stock, ventilate at 0.6 to 0.7 cubic meters per minute per ton. For chipping stock, use 0.8 to 1 cubic meter per minute per ton. If airflow is too high, the relative humidity surrounding the potatoes may drop, causing weight loss. Air-cooled storage rooms may also be used, but you must ensure that night temperatures are low enough to keep your storage room cool and high enough to prevent freezing. Hold table potatoes at 38 to 40 degrees F., decreasing field temperature 5 degrees per week to the desired storage temperature. Store processing potatoes at 50 to 55 degrees F., although Russet Burbank for processing can be stored at 45 degrees F. Cool processing potatoes to the final storage temperature at a rate of 3 to 4 degrees per week. Processing potatoes stored below 40 degrees F. will build up sugars that will cause the flesh to turn brown or black when fried. Once the desired holding temperature is reached, keep the temperature differential about 2 degrees F. between the top and bottom of the pile. Do not allow potatoes to remain at temperatures below 30 degrees F., or freezing injury will occur, leading to rot. For all types of potatoes, storage humidity should be 95%, but avoid moisture condensation on tubers and storage walls and ceilings. When diseases such as late blight and Pythium leak are severe, maintain lower humidity during storage and ensure good air circulation. EXAMPLE 1 In this study, acetaldehyde and 2-(E)-hexenal were chosen as prototype volatiles in order to investigate the use of plant volatiles for the control of potato blemish pathogens in fresh-pack potato packaging. The two main potato blemish disease pathogens, Colletotrichum coccodes (black dot) and Helminthosporium solani (silver scurf) were used in the study. Cultures of the two pathogens, grown on PDA, were exposed to the pure volatiles in sealed mason jars for 7 days at 23° C. Radial fungal growth and the concentration of the volatile were measured daily and the concentration required to inhibit fungal growth was determined. The objectives of this study were to determine the optimal concentrations of plant volatiles required to inhibit fungal growth, which volatile was more effective, and to determine whether the volatiles are fungistatic and fungitoxic or both. Preliminary results demonstrate that the use of these volatile compounds in active packaging systems for the control of potato blemish diseases. 2-(E)-hexenal showed nearly complete inhibition of three postharvest potato pathogens, Erwinia carotovora, Colletotrichum coccodes and Helminthosporium solani. 2-(E)-hexenal could be used to control these and other pathogens and extend the storability and shelf-life of potatoes. EXAMPLE 2 Acetylaldehyde and 2-(E)-hexenal were chosen as prototype volatiles to investigate the use of plant volatiles for the control of potato blemish pathogens. Three main potato blemish pathogens were used in the study: Erwinia carotovora, Colletotrichum coccodes and Helminthosporium solani. The objectives of this study were to determine the optimal concentration plant volatiles required to inhibit pathogenic growth, which volatile was more effective and whether the volatiles were toxic and static. 1 L jars were used. Pure volatile (2.5-10 μL/L) was inserted into the jars onto the side of the jar above 6 cm plates containing the pathogens. Controls and treatments were incubated at 23 degree C. until the control filled the plate. Diameter of the colony (mm) from control and treatments were evaluated daily using calipers. 2-E-Hexenal shows nearly complete inhibition for the tested postharvest pathogens at a low concentration of 2.5 μL/L.	This application relates to compositions and methods for inhibiting the growth of potato pathogens preventing disease during post-harvest storage and processing conditions.	0
FIELD OF THE INVENTION The present invention relates generally to Internet security and more specifically to the detection of computer attacks by an Internet “bot” (which is short for a program robot) or a network of related bots called a “botnet”. BACKGROUND OF THE INVENTION The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies. Computer and network systems are subject to a variety of attacks such as viruses, worms, trojans, unauthorized users, an individual bot or a botnet. A botnet is a collection of internet-connected programs communicating with other similar programs in order to perform tasks. These can be as mundane as keeping control of an Internet Relay Chat (IRC) channel, or malicious, as in the case of sending spam email, participating in distributed denial of service (DDoS) attacks, or other malicious activity. Typically a botnet refers to any group of computers, often referred to as zombie computers or bots, that have been recruited by executing malicious software. A botnet's originator, typically known as a “botherder” or “botmaster,” can control the group remotely, usually through an IRC channel, and often for criminal purposes. The botnet originator can communicate through the IRC channel via a server, known as the command-and-control (C&C) server. The means for communication in a centralized architecture is either IRC protocol or Hypertext Transfer Protocol (HTTP). The IRC protocol allows the botmaster to have real time communication with the bots. In the HTTP protocol, the botmaster does not communicate directly with the bots but rather, the bots periodically contact the C&C server to obtain their instructions. Some newer botnets communicate using a decentralized architecture by employing peer-to-peer (P2P) communication, with command-and-control embedded into the botnet rather than relying on C&C servers, thus avoiding any single point of failure. A firewall is a set of related programs used to help keep a network secure. Its primary objective is to monitor and control the incoming and outgoing network traffic by analyzing the data packets and determining whether each packet should be allowed through or not, based on a predetermined rule set. Features of a firewall may include logging, reporting, and a graphical user interface for controlling the firewall. SUMMARY Embodiments of the present invention provide for a program product, system, and method for detecting malicious intrusions (or bots) into a computer. The computer receives firewall log data that includes communication records containing the source and destination of the communication as well as the time of the communication. The source or destination of the communication may be on a list of suspicious servers known to contain malicious software. The computer identifies a sequence of communications between a common source address and a common destination address. The computer further identifies substantially fixed intervals between the communications, and generates an alert indicating a suspected bot intrusion. The computer also identifies from the sequence of communication, patterns in the communication intervals, similarly generating an alert indicating a suspected bot intrusion. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is a block diagram illustrating a botnet detection system in accordance with an embodiment of the present invention. FIG. 2 is a flowchart showing the operational steps of a monitoring program within the botnet detection system of FIG. 1 , in accordance with an embodiment of the present invention FIG. 3 is a block diagram of internal and external components of a computing device of FIG. 1 in accordance with an embodiment of the present invention. DETAILED DESCRIPTION The present invention will now be described in detail with reference to the Figures. FIG. 1 is a block diagram illustrating botnet detection system 100 , in accordance with one embodiment of the present invention. In an exemplary embodiment, botnet detection system 100 includes computing device 120 , client device 160 , computing device 130 , trusted server 140 , and untrusted server 150 , all interconnected via internal network 112 and external network 110 . Computing device 120 , trusted server 140 and untrusted server 150 are all interconnected via external network 110 , while computing device 120 , client device 160 and computing device 130 are all interconnected via internal network 112 . Computing device 120 includes firewall program 122 and firewall log 124 . In an exemplary embodiment, firewall program 122 is a program that monitors and controls the incoming and outgoing network communication between external network 110 and internal network 112 in order to protect internal network 112 from malicious activity. The network communication is typically in the form of data packets, which include at least a header and a payload. The header contains information including the source and destination of the communication, and the size of the data packet. Firewall program 122 saves a record of each network communication in firewall log 124 . Each record of firewall log 124 includes at least the source of a communication, the destination of a communication, and the time a communication was observed by firewall program 122 . Computing device 130 , connected to internal network 112 , includes monitoring program 132 and monitoring log 134 . Monitoring program 132 is capable of accessing firewall log 124 and operates to detect botnets as discussed in detail below. External network 110 may include one or more networks of any kind that provide communication links between various devices and computers. External network 110 may include connections, such as wired communication links, wireless communication links, or fiber optic cables. In one example, external network 110 is the Internet, a worldwide collection of networks and gateways that use the Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, governmental, educational and other computer systems that route data and messages. External network 110 may also be implemented as a number of different types of networks, such as for example, an intranet, a local area network (LAN), or a wide area network (WAN). In the depicted embodiment, trusted server 140 and untrusted server 150 are connected to external network 110 . Internal network 112 can be, for example, a local area network (LAN), a wide area network (WAN) such as the Internet, or a combination of the two, and can include wired, wireless, or fiber optic connections. Internal network 112 is separated from external network 110 by firewall program 122 of computing device 120 . In the depicted embodiment, client device 160 and computing device 130 are connected to internal network 112 . In general, external network 110 and internal network 112 can be any combination of connections and protocols that will support communications amongst client device 160 , computing device 130 , computing device 120 , trusted server 140 , and untrusted server 150 . In various embodiments of the present invention, each one of computing device 120 and computing device 130 can include a laptop, tablet, or netbook personal computer (PC), a desktop computer, a smart phone, a mainframe computer, or a networked server computer. Further, each one of computing device 120 and computing device 130 can include computing systems utilizing clustered computers and components to act as single pools of seamless resources, or can represent or exist within one or more cloud computing datacenters. Computing device 130 can be any programmable electronic device, which may include internal components 800 and external components 900 as described in further detail with respect to FIG. 3 , and which is capable of executing monitoring program 132 , creating monitoring log 134 , and accessing firewall log 124 . Monitoring program 132 operates to detect an individual bot or a plurality of bots of a botnet connected to, or within, internal network 112 . A botnet is a group of computers controlled by a botnet originator, usually to achieve a malicious purpose. The creation of a botnet begins with the download of a software program called a bot by an unsuspecting user to the user's computer. This can happen when the user clicks an infected e-mail attachment or Trojan Horse, or downloads infected files from peer to peer (“P2P”) networks or from malicious websites. Once the bot has been installed on the unsuspecting user's computing device (thereby creating an “infected device”), communication will be established between the bot and a command and control (“C&C”) server, or other bots in the case of P2P communication. This communication allows the botnet originator (the “botmaster”) to send commands to the bot and allows the bot to send the status about the infected device to the botmaster. Typically this communication uses public Internet Chat Relay (IRC) servers, but can also use Hypertext Transfer Protocol (HTTP), simple mail transfer protocol (SMTP), transmission control protocol (TCP), or user datagram protocol (UDP) communication. Monitoring program 132 analyzes the records in firewall log 124 to identify communication between a C&C server and a bot within a botnet. For example, monitoring program 132 can identify communication from a C&C server to a bot, or from a bot to a C&C server, or both. Communication between a C&C server and an infected device will often occur periodically, i.e. at a fixed interval such as every minute, or according to a more complex but repeating pattern of intervals. One example of a more complex pattern is alternating intervals of one minute and one hour. A further example of a more complex pattern is the insertion of one or more communications between the fixed interval communications. As such, the fixed interval is not necessarily between sequential communications or between sequential intervals. Monitoring program 132 examines the communication records stored in firewall log 124 to look for such similar or patterned communication between, for example, client device 160 and untrusted server 150 . In particular, monitoring program 132 maintains a collection of monitoring log records in monitoring log 134 , where each monitoring log record includes a collection of timestamp records for a common source address and destination address. Client device 160 can be, for instance, a desktop computing workstation, laptop, or mobile device within internal network 112 . Untrusted server 150 may be categorized as untrusted based on, but not limited to, factors such as its inclusion on a list of suspect servers, previous experience of malicious activity, or non-inclusion on a list of trusted servers. In one embodiment, monitoring program 132 compares the source address and the destination address to a list of suspect servers. Conversely, trusted server 140 may be categorized as trusted based on, but not limited to, factors such as its inclusion on a list of trusted servers, no history of malicious activity, or non-inclusion on a list of untrusted servers. If similar or patterned communication is detected, an alert is generated as to the possible existence of a botnet. FIG. 2 is a flowchart showing the operational steps of monitoring program 132 within botnet detection system 100 of FIG. 1 , in accordance with an embodiment of the present invention. After discussing the operational steps of monitoring program 132 in the context of steps 200 through 218 generally, a specific example of monitoring program 132 in operation will follow. Monitoring program 132 receives a record from firewall log 124 (step 200 ). In one embodiment, the log record identifies one or more prior communications through the firewall, including the source IP address, destination IP address, destination port, date and time of each communication. In an exemplary embodiment, a single monitoring log record is a collection of identities of communications with a common source IP address and destination IP address, each with its own timestamp. Monitoring program 132 then checks the firewall log record to determine if the source of a communication is an untrusted server and the destination is internal (decision 202 ). If the source of a communication is a trusted server, such as trusted server 140 , or the destination of a communication is not within internal network 112 (decision 202 , “NO” branch), the firewall log record requires no further evaluation by monitoring program 132 , and monitoring program 132 returns to step 200 to receive the next firewall log record. If the source of a communication is from an untrusted server, such as untrusted server 150 , and the destination is within internal network 112 , such as client device 160 , (decision 202 , “YES” branch) monitoring program 132 determines if a monitoring log record exists in monitoring log 134 for the particular source address and destination address of the communication of the received firewall log record (decision 204 ). The monitoring log record is also used to evaluate the time intervals between communications that take place between the common source address and destination address. As such, a monitoring log record includes a source address, a destination address, and potentially numerous timestamp records. In one embodiment, the monitoring log record includes communication that occurs in both directions. As such, the destination of a first communication is the source of a second communication, and the source of the first communication is the destination of the second communication. In a further embodiment, a state machine is used in place of the monitoring log record. Monitoring program 132 can create a monitoring log record for each unique pair of source address and destination address that have been included in a received firewall log record. If the monitoring log record does not exist for the current address pair of the communication (e.g., because no prior communication had occurred between the current address pair, etc.) (decision 204 , “NO” branch), monitoring program 132 creates a new monitoring log record using the current firewall log record (step 206 ). Monitoring program 132 then returns to step 200 to receive the next firewall log record. If the monitoring log record does exist for the current address pair (decision 204 , “YES” branch), then the monitoring log record is updated with the new timestamp record from the current firewall log record (step 208 ). Monitoring program 132 then determines if at least three timestamp records are present in the monitoring log record (decision 210 ). If at least three timestamp records are not present in the monitoring log record (decision 210 , “NO” branch), then monitoring program 132 returns to step 200 to receive the next firewall log record. If at least three timestamp records are present in the monitoring log record (decision 210 , “YES” branch), then monitoring program 132 determines if the time intervals are similar by checking the intervals between the timestamp records and calculating the difference between each pair of the timestamp records (decision 212 ). As such, monitoring program 132 determines whether two or more time intervals of the monitoring log record are similar. In determining that the time intervals are similar, in one embodiment monitoring program 132 does not require that the time intervals be precisely the same. In particular, monitoring program 132 may allow a level of variability to exist between the time intervals by, for example, requiring that the differences between the lengths of the intervals not exceed a threshold. For example, the threshold is a percentage of the interval, for instance, 10%. In a further example, the threshold is a fixed value, for instance, 5 minutes. Increasing the variability allowed by monitoring program 132 may increase the number of false positive results generated. A false positive result occurs when a legitimate communication is miscategorized as a communication to a botnet. Decreasing the variability allowed by monitoring program 132 may increase the number of false negative results generated. A false negative result is when a botnet communication is not identified, leaving internal network 112 vulnerable to malicious activity. The variability can also be based on recent statistical data for known bots and botnets that is collected and indicates how periodic, on the average, are communications between C&C servers and their bots. If monitoring program 132 determines that the time intervals are not sufficiently similar, (decision 212 , “NO” branch), then monitoring program 132 removes the monitoring log record from monitoring log 134 (step 214 ) and returns to step 200 to receive the next firewall log record. As such, in some circumstances monitoring program 132 may remove a given monitoring log record if only its first two intervals are not similar. Monitoring program 132 thus takes a conservative approach to detecting botnet communication at similar intervals, and avoids the complexity of detecting botnet communication according to a more complex pattern of intervals. In another embodiment, monitoring program 132 can defer removal of the monitoring log record and can attempt to detect a more complex pattern of intervals, as discussed below. If monitoring program 132 determines that the time intervals are sufficiently similar (decision 212 , “YES” branch), monitoring program 132 then determines if there are enough occurrences at similar intervals (decision 216 ). Factors that determine if enough occurrences exist include, but are not limited to; the number of timestamp records, the magnitude of the time intervals, the variability of the time intervals, the source address of the communication, and the destination address of the communication. For example, in one embodiment determining if enough occurrences exist includes determining that there have been at least two similar intervals. If monitoring program 132 determines that there are not enough occurrences at similar intervals (decision 216 , “NO” branch), then monitoring program 132 returns to step 200 to receive the next firewall log record. If monitoring program 132 determines that there are enough occurrences at similar intervals (decision 216 , “YES” branch), then monitoring program 132 generates an alert (step 218 ). In an exemplary embodiment, an alert is an email sent to a system analyst or other responsible person indicating the detection of a suspicious communication pattern. Having discussed the operational steps of monitoring program 132 in the context of steps 200 through 218 generally above, a specific example of monitoring program 132 in operation follows here. For example, monitoring program 132 receives a first firewall log record from firewall log 124 for a communication between untrusted server 150 and client device 160 at 13:58 on Feb. 25, 2013. Monitoring program 132 determines that untrusted server 150 is an untrusted server and that client device 160 is a client device of internal network 112 (step 202 ). Monitoring program 132 determines that a monitoring log record does not exist in monitoring log 134 for the pairing of untrusted server 150 and client device 160 (step 204 ), and creates a monitoring log record in monitoring log 134 for untrusted server 150 and client device 160 , such that the monitoring log record includes 13:58 on Feb. 25, 2013 as the first timestamp record (step 206 ) and returns to receive the next firewall log record. Monitoring program 132 receives a second firewall log record from firewall log 124 for another communication between untrusted server 150 and client device 160 at 15:00 on Feb. 25, 2013 (a number of additional firewall log records for communications between different pairs of devices may have been separately received by monitoring program 132 after receiving the first firewall log record of the current example, but prior to receiving this second firewall log record). Monitoring program 132 determines that untrusted server 150 is an untrusted server and that client device 160 is a client device of internal network 112 (step 202 ). Monitoring program 132 determines that a monitoring log record exists in monitoring log 134 for the pairing of untrusted server 150 and client device 160 (step 204 ), and updates the monitoring log record with the new timestamp record (step 208 ). Monitoring program 132 determines that there are not at least three timestamp records in the monitoring log record (step 210 ) and returns to receive the next firewall log record. Monitoring program 132 receives a third firewall log record from firewall log 124 for a communication between untrusted server 150 and client device 160 at 15:58 on Feb. 25, 2013. Monitoring program 132 determines that untrusted server 150 is an untrusted server and that client device 160 is a client device of internal network 112 (step 202 ). Monitoring program 132 determines that a monitoring log record exists in monitoring log 134 for the pairing of untrusted server 150 and client device 160 (step 204 ), and updates the monitoring log record with the new timestamp record (step 208 ). Monitoring program 132 determines that there are at least three timestamp records in the monitoring log record (step 210 ) and calculates the time intervals as 62 minutes and 58 minutes, respectively, and determines that the intervals are similar (step 212 ). Further, the monitoring program 132 determines that there are not enough occurrences at similar intervals, given a variability or four minutes and only two intervals, to create an alert (step 216 ) and returns to receive the next firewall log record. Monitoring program 132 receives a fourth firewall log record from firewall log 124 between untrusted server 150 and client device 160 at 16:58 on Feb. 25, 2013. After completing steps 202 , 204 , 208 and 210 as described above, monitoring program 132 calculates the time intervals as 62 minutes, 58 minutes, and 60 minutes, respectively, and determines that the intervals are similar (step 212 ). Further, the monitoring program 132 determines that there are enough occurrences at similar intervals, given a variability or four minutes and three intervals (step 216 ). Monitoring program 132 creates an alert (step 218 ). Having discussed the operational steps of monitoring program 132 in the context of steps 200 through 218 generally above, and having discussed a specific example of monitoring program 132 in operation above, a further embodiment of the present invention will now be discussed. In a further embodiment, monitoring program 132 detects botnet communication according to a more complex pattern of intervals. A C&C server may attempt to avoid detection by altering the time intervals for communication with a bot by using a repeating pattern. For example, the C&C server may communicate with a bot in a pattern of alternating time intervals (i.e., one hour, then four hours, then one hour, then four hours). Further, the C&C server may communicate with a bot using incremental time intervals (i.e., one hour, then two hours, then three hours, then two hours, then one hour). The presented patterns are illustrative examples and are not meant to be limiting. Monitoring program 132 can detect such patterns by allowing a number of non-similar time intervals at step 212 prior to removing the monitoring log at step 214 . The number of allowable non-similar intervals is set by the user based on factors that may include, but are not limited to, volume of network traffic, available memory, and sophistication of C&C communication. Repeating patterns can be further detected by checking for similarity in non-adjacent time intervals at step 212 . FIG. 3 is a block diagram of internal and external components of computing device 130 of FIG. 1 in accordance with an embodiment of the present invention. In particular, computing/processing device 130 includes respective sets of internal components 800 and external components 900 . Each of the sets of internal components 800 includes one or more processors 820 , one or more computer-readable RAMs 822 and one or more computer-readable ROMs 824 on one or more buses 826 , one or more operating systems 828 and one or more computer-readable tangible storage devices 830 . The one or more operating systems 828 and monitoring program 132 are stored on one or more of the respective computer-readable tangible storage devices 830 for execution by one or more of the respective processors 820 via one or more of the respective RAMs 822 (which typically include cache memory). In the illustrated embodiment, each of the computer-readable tangible storage devices 830 is a magnetic disk storage device of an internal hard drive. Alternatively, each of the computer-readable tangible storage devices 830 is a semiconductor storage device such as ROM 824 , EPROM, flash memory or any other computer-readable tangible storage device that can store but does not transmit a computer program and digital information. Each set of internal components 800 also includes a R/W drive or interface 832 to read from and write to one or more portable computer-readable tangible storage devices 936 that can store but do not transmit a computer program, such as a CD-ROM, DVD, memory stick, magnetic tape, magnetic disk, optical disk or semiconductor storage device. Monitoring program 132 can be stored on one or more of the respective portable computer-readable tangible storage devices 936 , read via the respective R/W drive or interface 832 and loaded into the respective hard drive or semiconductor storage device 830 . Each set of internal components 800 also includes a network adapter or interface 836 such as a TCP/IP adapter card or wireless communication adapter (such as a 4G wireless communication adapter using OFDMA technology). The program 132 can be downloaded to the respective computing/processing devices from an external computer or external storage device via a network (for example, the Internet, a local area network or other, wide area network or wireless network) and network adapter or interface 836 . From the network adapter or interface 836 , the programs are loaded into the respective hard drive or semiconductor storage device 830 . The network may comprise copper wires, optical fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. Each of the sets of external components 900 includes a display screen 920 , a keyboard or keypad 930 , and a computer mouse or touchpad 934 . Each of the sets of internal components 800 also includes device drivers 840 to interface to display screen 920 for imaging, to keyboard or keypad 930 , to computer mouse or touchpad 934 , and/or to display screen for pressure sensing of alphanumeric character entry and user selections. The device drivers 840 , R/W drive or interface 832 and network adapter or interface 836 comprise hardware and software (stored in storage device 830 and/or ROM 824 ). The programs can be written in various programming languages (such as Java, C+) including low-level, high-level, object-oriented or non object-oriented languages. Alternatively, the functions of the programs can be implemented in whole or in part by computer circuits and other hardware (not shown). Based on the foregoing, a computer system, method and program product have been disclosed for a method to analyzing internet communication using log data. However, numerous modifications and substitutions can be made without deviating from the scope of the present invention. Therefore, the present invention has been disclosed by way of example and not limitation.	A computer detects malicious intrusions (or bots) into a computer. The computer receives firewall log data that includes communication records containing the source and destination of the communication, as well as, the time of the communication. The source or destination of the communication may be on a list of suspicious servers known to contain malicious software. The computer identifies a sequence of communications between a common source address and a common destination address. The computer further identifies substantially fixed intervals between the communications, and generates an alert indicating a suspected bot intrusion. The computer also identifies from the sequence of communication, patterns in the communication intervals, similarly generating an alert indicating a suspected bot intrusion.	7
This application is a Continuation of application Ser. No. 08/030,138, filed Mar. 12, 1993, abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to processes for the treatment of nucleic acid material in order to effect a complete or partial change from double stranded form to single stranded form and to processes of amplifying or detecting nucleic acids involving such denaturation processes. 2. Description of the Prior Art Double stranded DNA (deoxyribonucleic acid) and DNA/RNA (ribonucleic acid) and RNA/RNA complexes in the familiar double helical configuration are stable molecules that, in vitro, require aggressive conditions to separate the complementary strands of the nucleic acid. Known methods that are commonly employed for strand separation require the use of high temperatures of at least 60° celsius and often 100° celsius for extended periods of ten minutes or more or use an alkaline pH of 11 or higher. Other methods include the use of helicase enzymes such as Rep protein of E. coli that can catalyse the unwinding of the DNA in an unknown way, or binding proteins such as 32-protein of E. coli phage T4 that act to stabilise the single stranded form of DNA. The denatured single stranded DNA produced by the known processes of heat or alkali is used commonly for hybridisation studies or is subjected to amplification cycles. U.S. Pat. No. 4,683,202 (Kary B Mullis et al, assigned to Cetus Corporation) discloses a process for amplifying and detecting a target nucleic acid sequence contained in a nucleic acid or mixture thereof by separating the complementary strands of the nucleic acid, hybridising with specific oligonucleotide primers, extending the primers with a polymerase to form complementary primer extension products and then using those extension products for the further synthesis of the desired nucleic acid sequence by allowing hybridisation with the specific oligonucleotides primers to take place again. The process can be carried out repetitively to generate large quantities of the required nucleic acid sequence from even a single molecule of the starting material. Separation of the complementary strands of the nucleic acid is achieved preferably by thermal denaturation in successive cycles, since only the thermal process offers simple reversibility of the denaturation process to reform the double stranded nucleic acid, in order to continue the amplification cycle. However the need for thermal cycling of the reaction mixture limits the speed at which the multiplication process can be carried out owing to the slowness of typical heating and cooling systems. It also requires the use of special heat resistant polymerase enzymes from thermophilic organisms for the primer extension step if the continuous addition of heat labile enzyme is to be avoided. It limits the design of new diagnostic formats that use the amplification process because heat is difficult to apply in selective regions of a diagnostic device and it also can be destructive to the structure of the DNA itself because the phosphodiester bonds may be broken at high temperatures leading to a collection of broken single strands. It is generally believed that the thermophilic polymerases in use today have a lower fidelity i.e. make more errors in copying DNA than do enzymes from mesophiles. It is also the case that thermophilic enzymes such as TAQ polymerase have a lower turnover number than heat labile enzymes such as the Klenow polymerase from E. coli. In addition, the need to heat to high temperatures, usually 90° celsius or higher to denature the nucleic acid leads to complications when small volumes are used as the evaporation of the liquid is difficult to control. These limitations have so far placed some restrictions on the use of the Mullis et al process in applications requiring very low reagent volumes to provide reagent economy, in applications where the greatest accuracy of copy is required such as in the Human Genome sequencing project and in the routine diagnostics industry where reagent economy, the design of the assay format and the speed of the DNA denaturation/renaturation process are important. Denaturation/renaturation cycles are also required in order to perform the so-called ligase chain reaction described in EP-A-0320308 in which amplification is obtained by ligation of primers hybridised to template sequences rather than by extending them. It is known that DNA has electrochemical properties. For example, N. L. Palacek (in "Electrochemical Behaviour of Biological Macromolecules", Bioelectrochemistry and Bioenergetics, 15, (1986), 275-295) discloses the electrochemical reduction of adenine and cytosine in thermally denatured single stranded DNA at about -(minus) 1.5 V on the surface of a mercury electrode. This reduction process also requires a prior protonation and therefore takes place at a pH below 7.0. The primary reduction sites of adenine and cytosine form part of the hydrogen bonds in the Watson-Crick base pairs. Palacek was unable to demonstrate reduction of adenine and cytosine in intact, native double stranded DNA at the mercury electrode. Palacek has further demonstrated that to a very limited extent the DNA double helix is opened on the surface of the mercury electrode at a narrow range of potentials centred at -(minus) 1.2 V in a slow process involving an appreciable part of the DNA molecule. This change in the helical structure of the DNA is thought to be due to prolonged interaction with the electrode charged to certain potentials and is not thought to be a process involving electron transfer to the DNA. No accumulation of single stranded DNA in the working solution was obtained and no practical utility for the phenomenon was suggested. Palacek also reports that the guanine residues in DNA can be reduced at -(minus) 1.8 V to dihydroguanine which can be oxidised back to guanine at around -(minus) 0.3 V. The reducible guanine double bond is not part of the hydrogen bonds in the Watson-Crick base pairs and this electrochemical process involving guanine does not affect the structure of the DNA double helix. In an earlier paper F. Jelen and E. Palacek (in "Nucleotide Sequence-Dependent Opening of Double-Stranded DNA at an Electrically Charged Surface", Gen. Physiol. Biophys., (1985), 4, pp 219-237), describe in more detail the opening of the DNA double helix on prolonged contact of the DNA molecules with the surface of a mercury electrode. The mechanism of opening of the helix is postulated to be anchoring of the polynucleotide chain via the hydrophobic bases to the electrode surface after which the negatively charged phosphate residues of the DNA are strongly repelled from the electrode surface at an applied potential close to -(minus) 1.2 V, the strand separation being brought about as a result of the electric field provided by the cathode. There is no disclosure of separating the strands of the DNA double helix while the DNA is in solution (rather than adsorbed onto the electrode) and there is no disclosure of useful amounts of single strand DNA in solution. Furthermore, there is no disclosure that the nucleotide base sequence of the DNA on the electrode is accessible from solution. The bases themselves are tightly bound to the mercury surface. A mercury electrode is a complex system and the electrode can only be operated in the research laboratory with trained technical staff. H. W. Nurnberg ("Applications of Advanced Voltammetric Methods in Electrochemistry" in "Bioelectrochemistry", Plenum Inc (New York), 1983, pp. 183-225) discloses partial helix opening of adsorbed regions of native DNA to a mercury electrode surface to form a so-called ladder structure. However, the DNA is effectively inseparably bound to or adsorbed onto the electrode surface. In this condition, it is believed that the denatured DNA is of no use for any subsequent process of amplification or hybridisation analysis. To be of any use, the denatured DNA must be accessible to subsequent processes and this is conveniently achieved if the single stranded DNA is available in free solution or is associated with the electrode in some way but remains accessible to further processes. Nurnberg has not demonstrated the ability of the mercury electrode to provide useful quantities of single stranded DNA. V. Brabec and K. Niki ("Raman scattering from nucleic acids adsorbed at a silver electrode" in Biophysical Chemistry (1985), 23, pp 63-70) have provided a useful summary of the differing views from several workers on DNA denaturation at the surface of both mercury and graphite electrodes charged to negative potentials. There has emerged a consensus amongst the research workers in this field that the denaturation process only takes place in DNA that is strongly adsorbed to the electrode surface and only over prolonged periods of treatment with the appropriate negative voltage, a positive voltage having no effect on the double helix. Brabec and Palacek (J. Electroanal. Chem., 88 (1978) 373-385) disclose that sonicated DNA damaged by gamma radiation is transiently partially denatured on the surface of a mercury pool electrode, the process being detectable by reacting the single stranded products with formaldehyde so as to accumulate methylated DNA products in solution. Intact DNA did not show any observable denaturation. SUMMARY OF THE INVENTION The present invention provides a process for denaturing double-stranded nucleic acid which comprises operating on solution containing nucleic acid with an electrode under conditions such as to convert a substantial portion of said nucleic acid to a wholly or partially single stranded form. It has been found that it is possible to produce the denaturation of undamaged (i.e. non-irradiated) DNA at ambient temperature by applying a suitable voltage to a solution in which the DNA is present under suitable conditions. The mechanism for the process has not yet been fully elucidated. It is believed that the process is one in which the electric field at the electrode surface produces the denaturation of the double helix when the DNA is in close proximity to the electrode but not bound irreversibly to it. The process is found to be readily reversible. In polymerase chain reaction processes exemplified hereafter, it is shown that the denatured DNA produced by the denaturing process of the invention is immediately in a suitable state for primer hybridisation and extension. On a larger scale, it is found that samples of denatured DNA produced using a negative voltage electrode can be caused or encouraged to renature by reversal of the voltage or by incubation at a higher temperature to encourage reannealing. Preferably, according to the invention, the single stranded nucleic acid produced is free from the electrode, e.g. in solution. Preferably, a potential of from -0.5 to -1.5 V is applied to said working electrode with respect to the solution, more preferably from -0.8 to -1.1 V, e.g. about -1.0 V. Working electrode voltages are Given throughout as if measured or as actually measured relative to a calomel reference electrode (BDH No. 309.1030.02). In addition to said electrode and a counter-electrode, a reference electrode may be contacted with said solution and a voltage may be applied between said electrode and said counter-electrode so as to achieve a desired controlled voltage between said electrode and said reference electrode. The electrodes may be connected by a potentiostat circuit as is known in the electrochemical art. The ionic strength of said solution is preferably no more than 250 mM, more preferably no more than 100 mM. As it has been found that the rate of denaturation increases as the ionic strength is decreased, the said ionic strength is still more preferably no more than 50 mM, e.g. no more than 25 mM or even no more than 5 mM. Generally, the lower the ionic strength, the more rapid is the denaturation. However, in calculating ionic strength for these purposes it may be appropriate to ignore the contribution to ionic strength of any component which acts as a promoter as described below. The solution may contain or the electrode may have on its surface a promoter compound which assists said denaturation. Although the invented process can take place in a solution containing only the electrode and the nucleic acid dissolved in water optionally containing a suitable buffer, the process can be facilitated by the presence in the solution containing the nucleic acid of such a promoter compound. The compound may act as a promoter serving either to destabilise the double-stranded nucleic acid, for instance by intercalation into the double helix, or to stabilise the single-stranded form, or else to facilitate interaction between the electrode surface and the nucleic acid. By way of analogy, it has been found that 4,4'-bipyridyl promotes the reduction of cytochrome C at a gold electrode even though bipyridyl is in itself electroinactive at the voltages used. (M. J. Eddowes and H. A. Hill, J. Chem. Soc. Chem. Commun. (1977), 771). The promotor may be any inorganic or organic molecule which increases the rate or extent of denaturation of the DNA double helix. It should be soluble in the chosen solvent. It preferably does not affect or interfere with DNA or other materials (such as enzymes or oligonucleotide probes) which may be present in the solution. Alternatively the promoter may be immobilised to or included in the material from which the electrode is constructed. In experiments, it has been found that the promoter may be a water soluble compound of the bipyridyl series, especially a viologen such as methyl viologen or a salt thereof. It is believed that the positively charged viologen molecules interact between the negatively charged DNA and the negatively charged cathode to reduce electrostatic repulsion therebetween and hence to promote the approach of the DNA to the electrode surface where the electrical field is at its strongest. Accordingly, we prefer to employ as promoters compounds having spaced positively charged centres, e.g. bipolar positively charged compounds. Preferably, the spacing between the positively charged centres is similar to that in viologens. Other suitable viologens include ethyl viologen isopropyl viologen and benzyl viologen. The process may be carried out in an electrochemical cell of the type described by C. J. Stanley, M. Cardosi and A. P. F. Turner "Amperometric Enzyme Amplified Immunoassays" J. Immunol. Meth (1988) 112, 153-161 in which there is a working electrode, a counter electrode and optionally a reference electrode. The working electrode at or by which the denaturing nucleic acid is effected may be of any convenient material e.g. a noble metal such as gold or platinum, or a glassy carbon electrode. The electrode may be a so called "modified electrode" in which the denaturing is promoted by a compound coated onto, or adsorbed onto, or incorporated into the structure of the electrode which is otherwise of an inert but conducting material. In an alternative electrochemical cell configuration the working, counter and reference electrodes may be formed on a single surface e.g. a flat surface by any printing method such as thick film screen printing, ink jet printing, or by using a photo-resist followed by etching. It is also possible that the working and reference electrodes can be combined on the flat surface leading to a two electrode configuration where the reference also acts as the counter. Alternatively the electrodes may be formed on the inside surface of a well which is adapted to hold liquid. Such a well could be the well known 96 well or Microtitre plate, it may also be a test tube or other vessel. Electrode arrays in Microtitre plates or other moulded or thermoformed plastic materials may be provided for multiple nucleic acid denaturation experiments. The strand separation may be carried out in an aqueous medium or in a mixture of water with an organic solvent such as dimethylformamide. The use of polar solvents other than water or non-polar solvents is also acceptable but is not preferred. The process may be carried out at ambient temperatures or if desired temperatures up to adjacent the pre-melting temperature of the nucleic acid. The process may be carried out at pH's of from 3 to 10 conveniently about 7. Generally, more rapid denaturation is obtained at lower pH. For some purposes therefore a pH somewhat below neutral, e.g. about pH 5.5 may be preferred. The nucleic acid may be dissolved in an aqueous solution containing a buffer whose nature and ionic strength are such as not to interfere with the strand separation process. The denaturing process according to the invention may be incorporated as a step in a number of more complex processes, e.g. procedures involving the analysis and or the amplification of nucleic acid. Some examples of such applications are described below. The invention includes a process for detecting the presence or absence of a predetermined nucleic acid sequence in a sample which comprises: denaturing a sample double-stranded nucleic acid by means of a voltage applied to the sample in a solution by means of an electrode; hybridising the denatured nucleic acid with an oligonucleotide probe for the sequence; and determining whether the said hybridisation has occurred. Thus, the invented process has application in DNA and RNA hybridisation where a specific gene sequence is to be identified e.g. specific to a particular organism or specific to a particular hereditary disease of which sickle cell anaemia is an example. To detect a specific sequence it is first necessary to prepare a sample of DNA, preferably of purified DNA, means for which are known, which is in native double stranded form. It is then necessary to convert the double stranded DNA to single stranded form before a hybridisation step with a labelled nucleotide probe which has a complementary sequence to the DNA sample can take place. The denaturation process of the invention can be used for this purpose in a preferred manner by carrying out the following steps: denaturing a sample of DNA by applying a voltage by means of an electrode to the sample DNA with optionally a promoter in solution or bound to or part of the structure of the electrode; hybridising the denatured DNA with a directly labelled or indirectly labelled nucleotide probe complementary to the sequence of interest; and determining whether the hybridisation has occurred, which determination may be by detecting the presence of the probe, the probe being directly radio-labelled, fluorescent labelled, chemiluminescent labelled or enzyme-labelled or being an indirectly labelled probe which carries biotin for example to which a labelled avidin or avidin type molecule can be bound later. In a typical DNA probe assay it is customary to immobilise the sample DNA to a membrane surface which may be composed of neutral or charged nylon or nitrocellulose. The immobilisation is achieved by charge interactions or by baking he membrane containing DNA in an oven. The sample DNA can be heated to high temperature to ensure conversion to single stranded form before binding to the membrane or it can be treated with alkali once on the membrane to ensure conversion to the single stranded form. The disadvantages of the present methods are: heating to high temperatures to create single stranded DNA can cause damage to the sample DNA itself. the use of alkali requires an additional step of neutralisation before hybridisation with the labelled probe can take place. One improved method for carrying out DNA probe hybridisation assays is the so called "sandwich" technique where a specific oligonucleotide is immobilised on a surface. The surface having the specific oligonucleotide thereon is then hybridised with a solution containing the target DNA in a single-stranded form, after which a second labelled oligonucleotide is then added which also hybridises to the target DNA. The surface is then washed to remove unbound labelled oligonucleotide, after which any label which has become bound to target DNA on the surface can be detected later. This procedure can be simplified by using the denaturing process of the invention to denature the double-stranded DNA into the required single-stranded DNA. The working electrode, counter electrode and optionally a reference electrode and/or a promoter can be incorporated into a test tube or a well in which the DNA probe assay is to be carried out. The DNA sample and oligonucieotide probes can then be added and the voltage applied to denature the DNA. The resulting single-stranded DNA is hybridised with the specific oligonucleotide immobilised on the surface after which the remaining stages of a sandwich assay are carried out. All the above steps can take place without a need for high temperatures or addition of alkali reagents as in the conventional process. The electrochemical denaturation of DNA can be used in the amplification of nucleic acids, e.g. in a polymerase chain reaction or ligase chain reaction amplification procedure. Thus the present invention provides a process for replicating a nucleic acid which comprises: separating the strands of a sample double stranded nucleic acid in solution under the influence of an electrical voltage applied to the solution from an electrode; hybridising the separated strands of the nucleic acid with at least one oligonucleotide primer that hybridises with at least one of the strands of the denatured nucleic acid; synthesising an extension product of the or each primer which is sufficiently complementary to the respective strand of the nucleic acid to hybridise therewith; and separating the or each extension product from the nucleic acid strand with which it is hybridised to obtain the extension product. In such a polymerase mediated replication procedure, e.g. a polymerase chain reaction procedure, it may not be necessary in all cases to carry out denaturation to the point of producing wholly single-stranded molecules of nucleic acid. It may be sufficient to produce a sufficient local and/or temporary weakening or separation of the double helix in the primer hybridisation site to allow the primer to bind to its target. Once the primer is in position on a first of the target strands, rehybridisation of the target strands in the primer region will be prevented and the other target strand may be progressively displaced by extension of the primer or by further temporary weakening or separation processes. Preferably, the said amplification process further comprises repeating the procedure defined above cyclicly, e.g. for more than 10 cycles, e.g. up to 20 or 30 cycles. In the amplification process the hybridisation step is preferably carried out using two primers which are complementary to different strands of the nucleic acid. The denaturation to obtain the extension products as well as the original denaturing of the target nucleic acid is preferably carried out by applying to the solution of the nucleic acid a voltage from an electrode. The process may be a standard or classical PCR process for amplifying at least one specific nucleic acid sequence contained in a nucleic acid or a mixture of nucleic acids wherein each nucleic acid consists of two Separate complementary strands, of equal or unequal length, which process comprises: (a) treating the strands with two oligonucleotide primers, for each different specific sequence being applied, under conditions such that for each different sequence being amplified an extension product of each primer is synthesised which is complementary to each nucleic acid strand, wherein said primers are selected so as to be substantially complementary to different strands of each specific sequence such that the extension product synthesised from one primer, when it is separated from its complement, can serve as a template for synthesis of the extension product of the other primer: (b) separating the primer extension products from the templates on which they were synthesised to produce single-stranded molecules by,applying a voltage from an electrode to the reaction mixture: and (c) treating the single-stranded molecules generated from step (b) with the primers of step (a) under conditions such that a primer extension product is synthesised using each of the single strands produced in step (b) as a template. Alternatively, the process may be any variant of the classical or standard PCR process, e.g. the so-called "inverted" or "inverse" PCR process or the "anchored" PCR process. The invention therefore includes an amplification process as described above in which a primer is hybridised to a circular nucleic acid and is extended to form a duplex which is denatured by the denaturing process of the invention, the amplification process optionally being repeated through one or more additional cycles. More generally, the invention includes a process for amplifying a target sequence of nucleic acid comprising hybridisation, amplification and denaturation of nucleic acid (e.g. cycles of hybridising and denaturing) wherein said denaturation is produced by operating on a solution containing said nucleic acid with an electrode. The process of the invention is applicable to the ligase chain reaction. Accordingly, the invention includes a process for amplifying a target nucleic acid comprising the steps of: (a) providing nucleic acid of a sample as single-stranded nucleic acid; (b) providing in the sample at least four nucleic acid probes, wherein: i) the first and second of said probes are primary probes, and the third and fourth of said probes are secondary nucleic acid probes; ii) the first probe is a single strand capable of hybridising to a first segment of a primary strand of the target nucleic acid; iii) the second probe is a single strand capable of hybridising to a second segment of said primary strand of the target nucleic acid; iv) the 5' end of the first segment of said primary strand of the target is positioned relative to the 3' end of the second segment of said primary strand of the target to enable joining of the 3' end of the first probe to the 5' end of the second probe, when said probes are hybridised to said primary strand of said target nucleic acid; v) the third probe is capable of hybridising to the first probe; and iv) the fourth probe is capable of hybridising to the second probe: and (c) repeatedly or continuously: i) hybridising said probes with nucleic acid in said sample; ii) ligating hybridised probes to form reorganised fused probe sequences; and iii) denaturing DNA in said sample by applying a voltage from an electrode to the reaction mixture. In all of the amplification procedures described above the denaturation of the DNA to allow subsequent hybridisation with the primers can be carried out by the application of an appropriate potential to the electrode. The process may be carried out stepwise involving successive cycles of denaturation or renaturation as in the existing thermal methods of PCR and LCR, but it is also possible for it to be carried out continuously since the process of chain extension or ligation by the enzyme and subsequent strand separation by the electrochemical process can continue in the same reaction as nucleic acid molecules in single-stranded form will be free to hybridise with primers once they leave the denaturing influence of the electrode. Thus, provided that the primer will hybridise with the DNA an extension or ligation product will be synthesised. The electrochemical DNA amplification technique can be used analytically to detect and analyse a very small sample of DNA e.g. a single copy gene in an animal cell or a single cell of a bacterium. The invention includes a kit for use in a process of detecting the presence or absence of a predetermined nucleic acid sequence in a sample which kit comprises, an electrode, a counter electrode and optionally a reference electrode, and an oligonucleotide probe for said sequence. The probe may be labelled in any of the ways discussed above. The invention also includes a kit for use in a process of nucleic acid amplification comprising an electrode, a counter electrode and optionally a reference electrode, and at least one primer for use in a PCR procedure, or at least one primer for use in an LCR procedure, and/or a polymerase or a ligase, and/or nucleotides suitable for use in a PCR process. Preferably, such kits includes a cell containing the electrodes. Preferably the kits include a suitable buffer for use in the detection or amplification procedure. The invention will now be described with reference to the following drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram of an electrochemical cell used for denaturation of DNA; FIG. 2 is a drawing of an electrophoresis gel showing the movement of single and double stranded DNA; FIG. 3 is a diagram of a electrophoresis gel showing the electrical denaturation of calf thymus DNA in the absence of any promoter such as methyl viologen; FIG. 4 is a diagram of a electrophoresis gel'showing the renaturation of denatured calf thymus DNA; FIG. 5 is a drawing of an electrophoresis gel showing the time course of the thermal denaturation of linear double stranded DNA from the bacteriophage M13 ; FIG. 6 is a drawing of an electrophoresis gel showing the time course of the electrical denaturation of linear M13 DNA; FIG. 7 is a drawing of an electrophoresis gel showing a comparison of a thermally amplified segment of M13 with an equivalent electrically amplified segment of M13 in the presence of methyl viologen; FIG. 8 is a drawing of an electrophoresis gel showing a comparison of a thermally amplified segment of M13 with an equivalent electrically amplified segment in the absence of methyl viologen. FIG. 9 is a drawing of an electrophoresis gel showing a fragment of `bluescript` DNA amplified using electrical PCR in the presence of methyl viologen; and FIG. 10 is a drawing of an electrophoresis gel showing amplified fragments of two `bluescript` DNA's produced by electrical PCR in the absence of methyl viologen. DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is shown a cell structure 10 comprising a working compartment 12 in which there is a body of DNA-containing solution, a working electrode 14, a counter electrode 16, a FiVac seal 19, a Kwik fit adaptor 21 and a magnetic stirrer 18. A reference electrode 20 in a separate side arm is connected via a "luggin" capillary 23 to the solution in the sample 12. The working electrode, counter electrode and reference electrode are connected together in a potentiostat arrangement so that a constant voltage is maintained between the working electrode 14 and the reference electrode 20. Such potentiostat arrangements are well known (see for example "Instrumental Methods in Electrochemistry" by the Southampton Electrochemistry Group, 1985, John Wiley and Sons, p 19). The electrode 14 is a circular glassy carbon rod of diameter 0.5 cm, narrowing to 0.25 cm at a height of 10 mM, and having an overall length of 9 cm inside a teflon sleeve of outside diameter 0.8 cm (supplied by Oxford Electrodes, 18 Alexander Place, Abingdon, Oxon), and the reference electrode 16 is a 2 mm pin calomel (supplied by BDH No 309/1030/02). The counter electrode is supported by a wire which is soldered to a brass sleeve 25 above the adaptor and passes down and exits the teflon sleeve 20 mm from the base of the working electrode. The wire attaches to a cylindrical platinum mesh counter-electrode supplied by Oxford Electrodes which annularly surrounds the working electrode. This cell is used in the following examples. EXAMPLE 1 In this example of DNA denaturation, the two methods of thermal and electrical denaturation have been compared. To achieve electrical denaturation, 1.60 ml of a solution of methyl viologen dichloride at 1 mg/ml in distilled water (adjusted to pH 7 by titration with 0.1M sodium hydroxide) was added to the working compartment of the electrochemical cell described above. The reference arm of the cell in which the reference electrode 20 resides contained 0.4 ml of this solution. A sample of 120 μl of a stock solution of calf thymus DNA (Sigma Chemical Company catalogue number: D4522, average fragment size 5,000 bases) at 1 mg/ml in distilled water (the pH was not adjusted) was added to the working chamber of the electrochemical cell to give a 70 μg/ml final DNA concentration. The total ionic strength of the solution was calculated to be approximately 5 mM. A voltage of -(minus) 1.0 V was applied between the working electrode and the reference electrode. The electrochemical cell was left for 16 hours at room temperature (22° C.) with continuous gentle stirring. On applying the potential to the working electrode 14 the blue colour of reduced methyl viologen was observed in the immediate vicinity of the working electrode. A 100 μl sample from the working compartment of the electrochemical cell was taken at the end of the experiment and prepared for gel electrophoresis analysis by mixing with 20 μof gel loading buffer which was the same as is described below for the gel itself which also contained 0.25% (w/v) bromophenol blue (BDH Indicators 200170), 0.25% (w/v) xylene cyanol (Sigma X2751), and 30% (v/v) glycerol (BDH AnalaR 100118). The mixtures were stored on ice prior to loading 10 μl samples in the wells cast in an agarose electrophoresis gel. For the thermal denaturation experiment the DNA solution at 1 mg/ml in distilled water (the pH was not adjusted) was heated to 100° C. for 10 minutes in a boiling water bath. The tube containing the thermally denatured DNA was then removed from the water bath and placed immediately into a beaker containing an ice/water mix to ensure rapid cooling to prevent renaturation of the Sample back to the double stranded form. A 100 μl sample of the thermally denatured DNA solution was prepared for gel electrophoresis by mixture with 20 μl of gel loading buffer which contained 0.25% (w/v) bromophenol blue, 0.25% (w/v) xylene cyanol and 30% (w/v) glycerol. Native intact calf thymus DNA was also prepared for gel electrophoresis by mixing 100 μl of the starting solution of DNA (before thermal or denaturation) with 20 μl of gel loading buffer and stored on ice until required. The gel (a section of which is shown in FIG. 2) had a number of wells 30 into which the samples could be loaded, and 10 μl samples were placed into individual wells. The gel had a total volume of 50 ml and was 10 cm wide and 75 cm long; it was 0.5% (w/v) agarose in 0.089M tris buffer pH 8.0 containing 0.1M borate and 0.01M sodium EDTA. The gel was run for 85 minutes at an applied constant voltage of 55 volts using a power supply from Pharmacia No 500/400. The gel was then removed from the electrophoresis apparatus and stained by addition of 0.75 ml of ethidium bromide (Pharmacia No 1840-501, lot 9503860E) at 20 μg/ml in distilled water. After staining for 30 minutes the gel was washed in distilled water. The stained gel was trans-illuminated with ultraviolet light and then photographed with a Polaroid instant camera system using a red filter to reduce background from the UV source. The gel shown in FIG. 1 has samples A, B and C. Sample A was the starting material used in the test (calf thymus DNA). Sample B was a sample of calf thymus DNA which had been electrically denatured according to the invention and sample C was a sample of thermally denatured DNA. The DNA stain ethidium bromide becomes fluorescent when it intercalates into the double helical structure of intact native DNA. Hence it can be used to identify the double stranded DNA in FIG. 1. As the DNA is denatured it becomes progressively single stranded and the efficiency of staining with ethidium bromide decreases. However, there is still some residual staining of single stranded calf thymus DNA, probably because there is still some ordering of the bases or even some regions which remain double stranded to which ethidium bromide can bind. Therefore the stain is still useful in detecting denatured DNA as well as intact DNA. In FIG. 1 it will be noted that the samples B and C are of much higher mobility than sample A through the gel indicating that the DNA after thermal denaturation and after electrical reduction has similar physical characteristics, showing a denaturation to the single stranded form which runs faster in this gel system. Similar results have been obtained using gold and platinum working electrodes. EXAMPLE 2 Example 1 was repeated as before, but DNA samples were taken after 15 minutes, 3 hours and 22 hours treatment in the electrochemical cell in order to provide a time course of the denaturation of the DNA. During sampling from the cell the potentiostat was switched to a dummy cell represented by a resistor. A gradual progressive denaturation of the DNA into the faster migrating form on the gel was observed. The gel pattern after 15 minutes (not shown) is interpreted to represent a mixture of partially and fully denatured DNA but no evidence of wholly native DNA was seen, and in later samples the proportion of fully denatured DNA continued to increase. EXAMPLE 3 In a number of runs at varying promotor concentrations and at a fixed DNA concentration of 20 μg/ml in the electrochemical cell and at an ionic strength of 15 mM to 150 mM the rate of DNA denaturation was found to be greatly accelerated by increasing the promoter concentration from 3 to 30 mg/ml. At the higher concentration denaturation of the DNA was almost complete in 15 minutes only. In this example, the overwhelmingly predominant source of ionic strength is the promotor itself. EXAMPLE 4 At a fixed promoter concentration of 3 mg/ml and at an ionic strength of 15 mM (derived essentially from the promoter) the rate of denaturation at various DNA concentrations was assessed. The results show that at 4 μg/ml DNA the denaturation time was reduced to under 0.5 hours (as assessed by the disappearance of the double stranded DNA band on the electrophoresis gel). The foregoing Examples demonstrate that the ratio of DNA to the promoter methyl viologen affects the rapidity and completeness of the denaturation of the DNA. These Examples were carried out at low ionic strength in distilled water. Repeating these Examples at higher ionic strength, i.e. 10 to 250 mM NaCl, lengthened the denaturation time of the DNA in solution by electrical means. This is attributed to the additional stabilisation that salt provides to the double helical structure of DNA. The foregoing Examples have also been repeated following exactly the procedure described above for calf thymus DNA with other whole genomic DNA samples from salmon testes DNA (Sigma No D1626) and with human placental DNA (Sigma No D7011). Exactly the same results were obtained on the agarose electrophoresis gel with these alternative DNA sources. EXAMPLE 5 FIG. 3 shows the results of an electrical DNA denaturation carried out according to the methods described above but without the inclusion of the methyl viologen promoter. The ionic strength was less than 1 mM and the calf thymus DNA concentration was 70 μg/ml. The electrochemical cell was left for a total of 20 hours at ambient temperature (22° C.) with continuous gentle stirring at a potential of -(minus) 1.0 V on the working electrode. Samples were taken from the cell at 1 hour, 3 hours and 4 hours as well as at the end of the procedure. During the sampling of the DNA solution from the cell the potentiostat was switched to a dummy cell represented by a resistor in order to avoid current surges. The gel in FIG. 3 shows that denaturation of the calf thymus DNA to the single stranded form does indeed occur in the absence of promoter, but the rate of the process was much slower than that observed with methyl viologen present. Track A is the starting material, Track B is after 1 hour, Track C after 3 hours, Track D after 4 hours and Track E after a total of 20 hours at -(minus) 1 V. Some limited denaturation of the DNA was observed within 1 hour but considerable amounts of intact double stranded DNA were still visible after 4 hours and only disappeared after overnight incubation. EXAMPLE 6 FIG. 4 shows the results from a renaturation procedure in which electrically denatured DNA has been treated under the appropriate thermal and electrical condition to recover the original double stranded DNA. To an electrochemical cell of the type shown in FIG. 1, 2.45 ml of distilled water was added to the working compartment and 0.2 ml of distilled water was added to the reference compartment. To the working compartment were added 250 [2l of calf thymus DNA at 1 mg/ml in distilled water (pH not adjusted) and 100 μl of a solution of methyl viologen at 100 mg/ml in distilled water (pH adjusted to pH 7 with 0.1M sodium hydroxide). The final DNA concentration in the solution was 90 μg/ml and the promoter 3.5 mg/ml. The ionic strength was approximately 15 mM derived essentially from the promoter. After gentle stirring of the contents of the cell with the magnetic stirring bar, a 100 μl sample was taken and stored on ice or frozen at -(minus) 20° C. The electrodes were positioned in the cell, as illustrated in FIG. 1, and a voltage of -(minus) 1 V was applied to the working electrode. The contents of the cell were stirred gently with the magnetic stirring bar and the conversion of the DNA to the single stranded form continued for 90 minutes at ambient temperature (22° C.). After 90 minutes the cell was switched to dummy and two 100 μl samples were taken, one sample was stored on ice the second was incubated at 55° C. in a water bath after addition of 2 μl of 10 times concentrated "reannealing buffer" (final concentration 20 mM NaCl, 2 mM Tris HCl pH 8.7, 0.2 mM EDTA) for 25 hours. The voltage at the working electrode was reversed to +(plus) 1 V and treatment of the DNA solution in the electrochemical cell proceeded for a further 25 hours. After this second time period 100 μl of the DNA solution was removed from the cell and stored on ice. Each of the 4 100 μl samples was mixed with 20 μl of gel loading buffer described above and stored on ice until required for electrophoresis. FIG. 4 is an agarose gel run exactly as described above showing the four DNA samples; A is the starting intact calf thymus material, B is the electrically denatured material, C is the electrically denatured and subsequently electrically renatured material, D is the electrically denatured material which was subsequently thermally renatured. It can be seen from the gel that both the electrically denatured thermally renatured and electrically denatured electrically renatured DNA returns to the original mobility of the double stranded starting material. EXAMPLE 7 This example illustrates that a bacteriophage genome can be electrically denatured to a single stranded form in a manner analogous to the thermal method. Bacteriophage M13 (M13mp18RF1 Double stranded form supplied by CP Laboratories, PO Box 22, Bishop's Stortford, Herts, UK) was employed. M13 is in circular form which can adopt a number of different coiled and supercoiled configurations. This leads to a complex set of bands on the agarose electrophoresis gel. Therefore the gel pattern was simplified to a single band by subjecting M13 to a restriction digest with the enzyme BgL I, which has only one restriction site on the M13 genome. To one vial of M13 as supplied by CP Laboratories (containing 10 μg of M13 in 100 μl of buffer 10 mM Tris HCl pH 7.5 1 mM EDTA) 10 μl of `restriction buffer` was added (0.1M Tris HCl pH 7.9, 0.01M Magnesium Chloride, 0.05M Sodium Chloride) and 6 μl of restriction enzyme (a stock at 8,000 U/ml supplied by CP Laboratories No 143S). The solution was incubated at 37° C. in a water bath for 16 hours. To ensure the linearisation was complete 1 μof the treated DNA was mixed with 3 μl of distilled water and 1 μl of gel loading buffer (described earlier) was run on a 1% agarose gel. If more than one band was seen after electrophoresis at 100 mA for 1 hour and subsequent staining, the DNA was redigested. Once linearity was determined the M13 was precipitated by adding 125 μl of 1M magnesium chloride, 25 μl of 3M sodium acetate and 125 μl of absolute ethanol (AnalaR grade from BDH Ltd, Poole, UK). The mixture was frozen in dry ice for 20 minutes for 16 hours and the precipitate was collected by 15 minute centrifugation after thawing. The pellet was washed with 0.15 ml of 70% (v/v) ethanol and collected again by centrifugation. Finally the pellet was dried under vacuum for 15 minutes and resuspended in 100 μl of distilled water. The linearised M13 DNA was then subjected to both thermal and electrical denaturation. A series of tubes was set up. The series of 6 tubes contained 1 μl M13 DNA with 4 μl of distilled water. One tube was placed on ice, and the other tubes were heated for 2,4,6,8,10 minutes in a boiling water bath. After a brief period of centrifugation the tubes were placed on ice (to prevent renaturation of the thermally denatured DNA). To each tube 1 μl of gel loading buffer was added. Before being loaded and subsequently run on a 1% agarose gel at 100 mA for 1 hour each tube was briefly vortexed. FIG. 5 shows the results from this thermal denaturation. Track A is the starting material (0 minutes at 100° C.), Track B is 2 minutes at 100° C., Track C is 6 minutes at 100° C. It can be clearly seen from the gel that the intact double stranded M13 rapidly disappears (within 4 minutes) from the gel as it denatures to single stranded form which does not bind ethidium bromide stain with high efficiency. A faint smear remains on the gel with a higher mobility Than native double stranded DNA and this may be the very faintly stained single stranded material. For the electrical denaturation experiment. 920 μl of distilled water was added to an electrochemical cell as illustrated in FIG. 1. 30 μl of a 100 mg/ml solution of methyl viologen indistilled water was added along with 50 μl of linearised M13 to the electrochemical cell. The solution was then mixed gently using the stirring bar. A potential of -(minus) 1.0 V was applied to the working electrode. Samples (50 μl) were taken at timed intervals, and stored on ice until required. The DNA was precipitated by adding 5 μl of 1M Magnesium Chloride, 25 μl of 3M Ammonium Acetate and 125 μl of absolute (100%) Ethanol to each sample. The precipitate was collected by freezing on dry ice and centrifuging as described above. The pellet was resuspended in 10 μl of distilled water and subjected to gel electrophoresis. FIG. 6 shows the time course of the electrical denaturation of M13 . Track A is the starting material, Track B is after 5 minutes, Track C is after 15 minutes. The gel shows the loss of the double stranded DNA structure which has disappeared by 15 minutes and the appearance of the faintly stained single stranded smear. EXAMPLE 8 FIG. 7 shows the results from an electrochemical cell polymerase chain reaction (PCR) carried out in the presence of the promoter methyl viologen. 30 μl of a methyl viologen stock at 100 mg/ml (so the working concentration of methyl viologen was 3 mg/ml) and 50 μl of stock linear M13 were added to 920 μl distilled water (pH not adjusted) in the working compartment of the cell and gentle stirring achieved by a stirring bar. 200 μl of a 3 mg/ml solution of methyl viologen was added To the reference electrode compartment of the cell. All parts of this procedure were carried out at ambient temperature (22° C.). For the initial cycle of the polymerase chain reaction a voltage of -(minus) 1 V was applied for 7 minutes and it was observed that the reduced form of the promoter methyl viologen was produced and accumulated such that all the liquid became blue. Then the potentiostat was switched to dummy. The working/counter electrode was removed from the cell and the solution left stirring for 3 minutes and it was observed that the blue colour rapidly disappeared during this period. Reagents were then added To the cell, with the stirrer bar still stirring, namely 6 μl of primer (M13 Sequencing primer (-47) 24 mer 5'(CGCCAGGGTTTTCCCAGTCACGAC)3' (SEQ ID NO: 1) supplied by ALTA Biosciences, University of Birmingham, UK as a 5 μg lyophilised powder) at a final concentration of 78 pmol, 6 μl of reverse primer M13 Reverse Sequencing primer (-24) 16 mer 5'd(AACAGTCATGACCATTG)3' (SEQ ID NO: 2) supplied as a 5 μg lyophilised powder) at a final concentration of 78 pmol, 13 μl of deoxynucleotide triphosphate mix (each dNTP present at a final concentration of 26 μm, supplied by Pharmacia Ltd., Midsummer Boulevard, Milton Keynes, UK), 4 μ, buffer mix (at final concentration of 6.6 mM Tris HCl pH 8, 1 mM MgCl 2 ) and then 10 μl of Klenow DNA polymerase (supplied by CP Laboratories, as 5,000 U/ml, and Northumbrian Biologicals Ltd, Cramlington Northumberland, as 5,000 U/ml). Excluding the promotor the ionic strength was therefore about 20 mM. There was then a 7 minute incubation, with gentle stirring for The first 1 minute and no stirring for the next 6 minutes. Then the working/counter electrode was replaced and the second cycle of the polymerase chain reaction started by -(minus) 1 V being applied for 5 minutes and it was observed that the reduced form of the promoter methyl viologen was produced and accumulated such that all the liquid became blue. Then the potentiostat was switched to dummy. The working/counter electrode was removed from the cell and the solution left stirring for 3 minutes and it was observed that the blue colour rapidly disappeared during this period. Reagents were then added to the cell, with the stirrer bar still stirring, i.e. 13 μl of deoxynucleotide triphosphate mix (details as above) and then 2.5 μl of Klenow DNA polymerase (details as above). There was then a 7 minute incubation, with gentle stirring for the first 1 minute and no stirring for the next 6 minutes. The second cycle was repeated as third to tenth cycles, omitting the adding of reagents at the end of the tenth cycle. A sample was taken from the working compartment of the cell (750 μ) and it was split into sub-samples for ease of processing (3×250 μl), Then to each tube was added 50 μl 1M Magnesium Chloride, 98 μl 3M Sodium Acetate and 500 μl 100% Ethanol. The samples were frozen on dry ice for 20 minutes and then after thawing centrifuged for 15 minutes to obtain a pellet. The pellet was washed with 250 μl of 70% ethanol and centrifuged as described before. The pellet was dried under vacuum for 15 minutes and then the pellet in each tube was resuspended in 7 μl distilled water (pH not adjusted) and after extensive vortexing and leaving on ice, the contents of the 3 tubes pooled before running on a gel. 4 μl of gel loading buffer was added to the sample prior to running on a 12% polyacryamide electrophoresis gel (made according to the following recipe for three mini gels: 42 ml distilled H 2 O, 8 ml TBE buffer (a stock of 500 ml distilled water containing 54 g Trizma Base (Sigma T1503) 25 g Boric acid (Sigma B0252) 20 ml 0.5M EDTA pH 8 (BDH 10093)), 24 ml 40% Acrylamide solution (BDH 44354), 6 ml of 2% N'N' methylene bis acrylamide solution (BDH 44355), 400 μl 15% Ammonium persulphate solution in distilled water (Sigma A7262), 100 μl TEMED (BDH 44308)). In FIG. 7, lane A contains primers, these run faster on the gel than the thermally amplified 119 base pair fragment in lane B. Lanes C and D contain 5 μl and 15 μl, respectively, of electrically amplified product. In lanes C and D high molecular weight M13 DNA is contained in the well, there is some smearing of DNA in the upper part of the gel, this is more pronounced in lane D. In both lanes, primers can be seen at the same mobility as in lane A, however in lane D extensive "flaring" of the primers is observed. The amplified product can be seen in both lanes C and D at the same mobility as the thermally amplified sample in lane B. EXAMPLE 9 FIG. 8 shows the results from an electrochemical cell polymerase chain reaction (PCR) experiment carried out in the absence of promoter. The method used was essentially the same as for Example 8 with promoter described above except that no promoter is added to the cell and all additions of primer and reverse primer were of 3 μl each (not 6 μl as described above) and the experiment ran for 15 cycles. In FIG. 8 lane A contains a thermally amplified 119 bp product, lane B primers, and lane E stock M13 that is confined to the well due to its high molecular weight. Lanes C and D contain the product of electrical amplification. The 119 base pair amplified region is clearly visible at the same mobility on the gel as the thermally amplified product. The primers in lanes C and D run at the same mobility as lane B. The reduction of the amount of primers added in this experiment in comparison to the experiment illustrated in FIG. 7 reduces the flaring effect in the gel. EXAMPLE 10 SK `Blue script` (Stratagene) is a circular 2,964 base pair vector. It contains a polylinker region which contains the M13 primer binding sites between which the target region of DNA amplified in Examples 8 and 9 is located. Before use in this Example the blue script was linearised using restriction enzyme Xmn 1; this cuts at site 2645. Thus To 80 μmoles of blue script, approximately 50 ug of DNA, 2.5 μl of -0.13M-Tris buffer pH 7.9 containing 0.13M magnesium chloride and 0.3M sodium chloride and 8 μl of Xmn 1 restriction enzyme (Stratagene) was added. The mixture was incubated at 37° C. overnight. After phenol chloroform extraction and ethanol precipitation the sample was resuspended to 50 μl in distilled water. To the working compartment of the cell of FIG. 1 was added 1.2 ml of distilled water, and 30 μl of 100 mg/ml stock methyl viologen. 200 μof this mixture was pipetted into the reference compartment. 50 μl (approximately 45 μg) of restriction digested SK blue script was added to the working compartment of the cell and the electrodes were placed in their respective compartments. Denaturing was conducted for 7 minutes at -1 V, and the working and counter-electrodes were removed from the cell. After 3 minutes stirring, to allow the reoxidation of the methyl viologen (a lagphase), the reagents listed below were added. The nucleic acid was allowed to anneal and extend for 5 minutes, the first minute with stirring the subsequent 4 minutes in the absence of stirring. The denaturing, lag phase and reagent addition, annealing and extending step were repeated for 10 cycles, but in cycles 2-10 the denaturation step was for 5 minutes. Addition of reagents: Cycle 1 4 μl of 1.65M Tris buffer pH 8.7 containing 330 mM magnesium chloride 13 μl of dATP, dGTP, dTTP and dCTP at 10 mM each in distilled water (CHASE) 10 μl of Klenow DNA polymerase--as in Example B 3 μl of each of concentrated primer (2) Cycle 2-4 and 6-10 5 μl of CHASE 2.5 μl of Klenow DNA polymerase After the 10 cycles were completed, the sample was divided into three and ethanol precipitated, dried and resuspended in 15 μl of distilled water. The sample was run on a 12% polyacrylamide gel at a constant current of 100 mA for 1 hour. The gel was stained with ethidium bromide. The gel is shown in FIG. 9. Both the thermally amplified product of M13, a 119 bp band, (run as a standard) and the primers can be clearly seen in lanes B and C respectively. Due to the high concentration of DNA loaded on to lane A, the lane had high background but a band of greater than 119 bp could be clearly seen. This band is the 200 bp amplified region of SK blue script. EXAMPLE 11 The procedure of Example 10 was repeated except that further restriction digests were performed to produce 20 μg of linear 3000 base pair bluescript DNA using Xmn 1, and 15 μg of 450 base pair blue script DNA using Pvu 2 (Stratagene). The electrical PCR amplification process was performed in the absence of methyl viologen. A lag phase was not necessary and was omitted. The polyacrylamide gel is shown in FIG. 10. Lane A contains a `ladder marker`, a set of known DNA sizes, which is used to gauge the molecular weight of experimental samples. Lane B contains the 450 base pair electrically amplified `blue script` DNA. The template 450 base pair band can be clearly seen, as can an amplified band of 200 base pairs. Lane C contains the 3000 base pair linear electrically amplified `blue script` DNA. The template DNA is confined to the well (as might be expected due to its 3000 base pair size) and an amplified band of 200 base pairs can clearly be seen. Many modifications and variations of the invention as specifically described above are possible within the scope of the invention. __________________________________________________________________________SEQUENCE LISTING(1) GENERAL INFORMATION:(iii) NUMBER OF SEQUENCES: 2(2) INFORMATION FOR SEQ ID NO: 1:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 24 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iii) ANTI-SENSE: NO(vi) ORIGINAL SOURCE:(A) ORGANISM: none(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1:CGCCAGGGTTTTCCCAGTCACGAC24(2) INFORMATION FOR SEQ ID NO: 2:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 17 base pairs( B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iii) ANTI-SENSE: NO(vi) ORIGINAL SOURCE:(A) ORGANISM: none(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 2:AACAGTCATGACCATTG 17__________________________________________________________________________	A process is described for denaturing native double-stranded nucleic acid material into its individual strands in an electrochemical cell. The process disclosed is an electrical treatment of the nucleic acid with a voltage applied to the nucleic acid material by an electrode. The process may also employ a promotor compound such as methyl viologen to speed denaturation. The process may be used in the detection of nucleic acid by hybridizing with a labelled probe or in the amplification of DNA by a polymerase chain reaction or ligase chain reaction.	2
FIELD OF THE INVENTION The present application provides methods and compositions for using polymorphisms in the STAT6 gene that are associated with economically important feedlot and carcass traits in livestock animals. BACKGROUND OF THE INVENTION The cost of feeding is the single largest variable cost in beef production systems, accounting for approximately 70% of the total production cost (Perry and Cecava, 1995, Beef Cattle Feeding and Nutrition, 2nd Ed., Academic Press, San Diego, Calif.). Generally, about 70-75% of the total dietary energy consumed in a beef production system is used for maintenance (Ferrell and Jenkins 1984, J. Anim. Sci. 58:234-243; NRC (National Research Council) 1996, Nutrient Requirements of Beef Cattle , Seventh Reviewed Edition, Washington, D.C.: National Academy Press). This means higher beef production costs, especially in large-sized breeding animals due to presumably higher maintenance energy needs, lower overall production system efficiency, and therefore lower profits. Indeed, compared to swine and poultry, which are able to convert about 14 and 22%, respectively, of the total energy intake into protein deposition, only 5% of the total energy intake in beef cattle is converted into deposited protein. Improvements in the efficiency of feed utilization by beef cattle would therefore lead to better economic returns from both beef cattle breeding operations and feedlots (Gibb and McAllister, 1999, “The impact of feed intake and feeding behaviour of cattle on feedlot and feedbunk management,” Pages 101-116. D. Korver and J. Morrison (ed). Proc. 20th Western Nutr. Conf. Canada; Liu et al., 2000, Can. J. Anim. Sci. 80:435-441; Herd et al., 2003, J. Anim. Sci. 81(E. Suppl. 1):E9-E17). According to Johnson et al. (2003) J. Anim. Sci. 2003. 81:E27-E38, the reasons for the lack of change in beef cattle energetic efficiency, despite several years of intensive production, include the lack of a consistent selection goal, loose and inconsistent definitions of efficiency, concentration on output traits, and emphasis on population similarities rather than individual variation. Efficient beef cattle production involves a complex summation of appropriate levels of available feed inputs and product outputs over a range of different production systems involving animals at different developmental stages. Thus, several indices have been proposed for determining the energetic efficiency of beef production, as comprehensively reviewed by Archer, et al. (1999) Australian Journal of Agricultural Research 50:147-161. These include feed conversion ratio (FCR), maintenance efficiency, partial efficiency of growth (PEG), cow-calf efficiency, and residual feed intake (RFI). Two other indices are relative growth rate (growth relative to instantaneous body size) and Kleiber ratio (weight gain per unit metabolic body size). Traditionally, feed efficiency has been expressed in terms of FCR, or its inverse (gross feed efficiency, GFE). This is usually measured as the ratio of feed consumed to gain in weight. It reflects the efficiency of use of the energy consumed for maintenance and growth and captures the relationship between input of feed and output of product (Herd et al., 2003, supra). Though FCR has been in existence for many years, it is difficult to improve through direct selection because it is difficult to measure on the individual and its genetic correlation with growth rate implies that selection for it can lead to an increase in body weight (BW) and feed intake, which is not always desirable (Gunsett, 1984, J. Anim. Sci. 59: 1185-1193; Archer et al., 1999, supra; Crews, 2005, Genet. Mol. Res. 4 (2): 152-165). On the other hand, several studies in different species have demonstrated considerable phenotypic and genetic variations among individual animals in feed intake above and below the predicted requirements for maintenance and growth (Foster et al., 1983, Anim. Prod. 37:387-393; Luiting and Urff, 1991, Poult. Sci. 70:1663-1672; Archer et al., 1998, Anim. Sci. 67:171-182; Archer et al., 1999, supra). This variation in intake is usually measured as RFI, and was first proposed for use in cattle by Koch et al. (1963) J. Anim. Sci. 22:486-494. Ultimately, the resulting phenotypic information collected using automated feed intake monitoring systems could be employed to dissect the molecular architecture of several economically relevant, but complex traits (ERT) in beef cattle. Molecular techniques can be employed to detect and map the chromosomal locations of genes contributing to variation in growth, feed intake, energetic efficiency, feeding behavior, and carcass merit. Several molecular tools and approaches, as well as statistical and computational techniques, are available that can be employed to quantify the number(s), location(s) and effect(s) of quantitative trait loci (QTL) through the use of genotypic information from genetic markers that are evenly spaced along chromosomes in the genome. A QTL is defined as the chromosomal location of individual or groups of genes, of unknown primary function, that show(s) significant association with a complex trait of interest (Lander and Kruglyuak, 1995, Natural Genet 11: 241-247). In beef cattle, QTL have been detected for disease tolerance (Hanotte et al., 2003, PNAS Agricultural Sciences 100:7443-7448), fertility and reproductive performance (Kirkpatrick et al., 2000, Mammalian Genome 11:136-139), body conformation (Grobet et al., 1998, Mammalian Genome 9: 210-213), birth weight and growth performance (Davis et al., 1998, Proc. 6 th World Congr. Genet. Appl. Livest. Prod. 23: 441-444; Casas et al., 2003, J. Anim. Sci. 81, 2976-83; Li et al., 2002, J. Anim. Sci. 80:1187-1194; Kim et al., 2003, J. Anim. Sci 81, 1933-42), and carcass and meat quality (Keele et al., 1999, J. Anim. Sci 77, 1364-1371; Casas et al., 2000, J. Anim. Sci. 78:560-569; MacNeil and Grosz, 2002, J. Anim. Sci. 80:2316-2324; Casas et al., 2003, supra; Kim et al., 2003, supra; Moore et al., 2003, J. Anim. Sci. 81:1919-1925; and Li et al., 2004, J. Anim Sci. 2004 82: 967-972). It is possible to search for and identify associations between polymorphisms in specific candidate genes and measures of variation in feed intake, feed efficiency and feeding behavior. A candidate gene may be selected based on previously known biochemical or physiological information or may be chosen because it maps to or close to the location of a QTL (positional candidate gene). Of interest among these candidates are genes shown to affect feed intake, behavior, energy balance, and body composition, such as the appetite regulating gene leptin. Several polymorphisms in candidate genes have been shown to be associated with economically relevant traits in cattle (Chrenek et al., 1998, Czech Journal of Animal Science 43, 541-544; Barendse et al., 2001, “The TG5 DNA marker test for marbling capacity in Australian feedlot cattle,” on the worldwide web at beef.crc.org.au/Publications/MarblingSym/Day1/Tg5DNA; Ge et al., 2001, J. Anim. Sci. 79:1757-1762; Grisart et al., 2002, Genome Research 12:222-231; Buchanan et al., 2002; Genet. Sel. Evol. 34:105-116; Moore et al., 2003, J. Anim. Sci. 81:1919-1925; Li et al., 2004, supra; and Nkrumah et al., 2005, J. Anim. Sci. 83:20-28). The bovine microsatellite ETH10, located on bovine chromosome 5, has recently been associated with marbling (deposition of intramuscular fat) in Asian breeds of cattle (Smith et al. 2001, J. Animal Sci 79:3041-51; and U.S. Pat. No. 6,383,751 (“the '751 patent”)). The '751 patent suggests that differences in marbling score, between related cattle with different ETH10 genotypes, is likely due to a closely linked gene. The '751 patent proposes that retinol dehydrogenase (11-cis and 9-cis) (RDH5), which maps 1.01 centi-rads (cR) from ETH10 on the bovine radiation hybrid map (Womack et al. 1997, Mamm Genome 8:854-6), was the responsible gene. The association between ETH10 and marbling was highly significant with a P-value of <0.00015. Even though strong linkage disequilibrium would exist in the population tested, a P-value of this magnitude suggests that the gene responsible might be more closely linked to ETH 10 than RDH5. Using a bioinformatics-based method to identify sequence homologies between bovine microsatellites and gene sequences from other species, it was demonstrated that ETH10 was putatively located within the 5′ UTR of the bovine STAT6 gene (Farber and Medrano, 2003, Animal Genetics 34:11-18). To support the location of ETH10, a bovine sequence tagged site (STS) in the 3′ UTR of bovine STAT6 was designed from available EST sequences. STAT6 is the principal transcription factor involved in interlukin-4 (IL-4) and IL-13 signaling (Takeda et al. 1997, J Mol Med 75:317-326). In this context, a polymorphic microsatellite (homologous to ETH10) in the first exon of human STAT6 has been associated with predisposition to allergic diseases, due to altered IL-4 and IL-13 signal transduction (Tamura et al. 2001, Clinical and Experimental Allergy 31:1509-1514). More importantly, STAT6 has been shown to be activated by the full length form and not the truncated form of the leptin receptor in cell culture, implicating it as a potential mediator of the anti-obesity effects of leptin (Ghilardi et al. 1996, Proc Natl Acad Sci USA 93:6231-6235). As a mediator of leptin signaling, different allelic forms of STAT6 could impact the level of circulating leptin, which would have a direct impact on the mass of adipocytes (Maffei et al. 1995, Nature Med 1:1155-61). The present invention provides SNPs within the STAT6 gene that are correlated with economically important feedlot and carcass traits in livestock animals. BRIEF SUMMARY OF THE INVENTION A variety of characteristics of livestock animals are considered important in determining the overall value of the finished product. Some factors are involved in the palatability of the meat produced, which is important to consumers, and which is reflected in the grading system used to classify meat. Still other factors affect the cost of producing an animal of given size and therefore affect the cost of meat that the consumer will ultimately pay, and which will result in improved profitability for producers of livestock as well as the operators of feedlots. As a result, methods of production that can improve the quality, or reduce the cost of production are desirable for all concerned in the production and consumption of meat from livestock. The present invention is based in part on the discovery of SNPs that are associated with a variety of parameters related to carcass and feedlot traits of livestock animals. Knowledge of the STAT6 genotype of livestock animals permits the development of genetic testing methods such that animals with the most desirable characteristics with regard to carcass weight and fat distribution, average daily weight gain and rib eye area can be identified and selected. This in turn leads to the development of methods of livestock management, wherein a higher degree of predictability about the eventual development of livestock animals becomes possible, once the genotype of animals with regard to the STAT6 gene is determined. Accordingly, the present inventions provides compositions and methods for using SNPs in the STAT6 gene to identify livestock animals (e.g., Bos , bovines) with desirable feedlot and carcass traits. In one aspect, the invention provides methods of selecting individual livestock animals, e.g., bovines, with desirable traits based on the knowledge of the animal's STAT6 genotype. In some embodiments, the methods comprise the steps of: determining the STAT6 alleles of the animal, e.g., bovine, at one or more SNP IDs selected from the group consisting of 14636, 16084 and 19597 of a gene encoding STAT6; wherein the traits are selected from the group consisting of back fat, calculated yield grade, cutability, hot carcass weight, dry matter intake, days on feed, back fat rate and average daily gain, wherein: i) a “CC” genotype at SNP ID 16084 is indicative of decreased back fat, a lower calculated yield grade, and increased cutability in comparison to an “AC” or “AA” genotype; ii) an “AA” genotype at SNP ID 19597 is indicative of increased hot carcass weight, increased dry matter intake and fewer days on feed in comparison to a “AG” or “GG” genotype; iii) a “CC” genotype at SNP ID 14636 is indicative of increased back fat rate, fewer days on feed, and increased average daily gain in comparison to a “CG” or “GG” genotype. In some embodiments, the methods further comprise the step of selecting the livestock animal with the desirable trait based on the animal's STAT6 genotype. In another aspect, the invention provides methods for distinguishing bovines having one or more STAT6 gene polymorphisms. In some embodiments, the methods comprise a) amplifying one or more regions or alleles of the bovine STAT6 gene using an oligonucleotide pair to form nucleic acid amplification products comprising amplified STAT6 gene polymorphism sequences; b) detecting one or more polymorphisms present in the bovine STAT6 gene at a SNP ID selected from the group consisting of 14636; 16084 and 19597; and c) analyzing the one or more polymorphisms, wherein i) a “CC” genotype at SNP ID 16084 is indicative of decreased back fat, a lower calculated yield grade, and increased cutability in comparison to an “AC” or “AA” genotype; ii) an “AA” genotype at SNP ID 19597 is indicative of increased hot carcass weight, increased dry matter intake and fewer days on feed in comparison to a “AG” or “GG” genotype; and iii) a “CC” genotype at SNP ID 14636 is indicative of increased back fat rate, fewer days on feed, and increased average daily gain in comparison to a “CG” or “GG” genotype. With respect to the methods for identifying animals with desirable feedlot or carcass traits based on their STAT6 genotype, in some embodiments, the step of determining or analyzing comprises determining the STAT6 allele of the animal at SNP ID 14636, wherein a “CC” genotype at SNP ID 14636 is indicative of increased back fat rate, fewer days on feed, and increased average daily gain in comparison to a “CG” or “GG” genotype. In some embodiments, the step of determining or analyzing comprises determining the STAT6 allele of the animal at SNP ID 16084, wherein a “CC” genotype at SNP ID 16084 is indicative of decreased back fat, a lower calculated yield grade, and increased cutability in comparison to an “AC” or “AA” genotype. In some embodiments, the step of determining or analyzing comprises determining the STAT6 allele of the animal at SNP ID 19597, wherein an “AA” genotype at SNP ID 19597 is indicative of increased hot carcass weight, increased dry matter intake and fewer days on feed in comparison to a “AG” or “GG” genotype. In some embodiments, the livestock animal is from the genus Bos . In some embodiments, the livestock animal is a bovine. In some embodiments, the livestock animal is a Bos taurus . In some embodiments, the livestock animal is a Bos indicus. In some embodiments, two or more polymorphisms are determined, e.g., are amplified. In some embodiments, one, two or three polymorphisms are determined, e.g., are amplified. In some embodiments, the gene encoding bovine STAT6 shares at least 95% sequence identity to SEQ ID NO:1 or the complement thereof. In some embodiments, the SNP ID 14636 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:2. In some embodiments, the SNP ID 16084 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:3. In some embodiments, the SNP ID 19597 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:4. In some embodiments, the STAT6 alleles are independently detected by an amplification reaction using polynucleotides that distinguish between alleles at SNP IDs 14636, 16084 or 19597. In some embodiments, the amplification reaction is selected from the group consisting of polymerase chain reaction (PCR), strand displacement amplification (SDA), nucleic acid sequence based amplification (NASBA), rolling circle amplification (RCA), T7 polymerase mediated amplification, T3 polymerase mediated amplification and SP6 polymerase mediated amplification. In some embodiments, the STAT6 alleles are independently detected by hybridization using polynucleotides that distinguish between alleles at SNP IDs 14636, 16084 or 19597. In some embodiments, the STAT6 alleles are independently detected by sequencing a subsequence of a gene encoding STAT6, the subsequence comprising SNP IDs 14636, 16084 or 19597. In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 14636, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-GCTGGTCACTCTTCCTAATC-3′ (SEQ ID NO:11) and 5′-TCTGACTTAGGGATCACCTC-3′ (SEQ ID NO:12); and a reverse primer comprising a nucleic acid sequence selected from 5′-GACCTCTATCTCTACCCTAC-3′ (SEQ ID NO:13); 5′-ACCTCTATCTCTACCCTACG-3′ (SEQ ID NO:14) and 5′-CTCTACCCTACGGGGAC-3′ (SEQ ID NO:15). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 16084, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-TTTCCCTACTGCCCCATTGC-3′ (SEQ ID NO:16); 5′-TCAGAGAGCTTTCCCTACTG-3′ (SEQ ID NO:17); and 5′-CCTGTCTCTTACCCTCT-3′ (SEQ ID NO:18); and a reverse primer comprising the nucleic acid sequence 5′-TAATGGAGTGGGAAGAGCTG-3′ (SEQ ID NO:19). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 19597, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-CACACTCGTCACCAGGTATG-3′ (SEQ ID NO:20) and 5′-GAGCCCCCCTGCCTG-3′ (SEQ ID NO:21); and a reverse primer comprising a nucleic acid sequence selected from 5′-AACTCTGACCCTCCTGTTTC-3′ (SEQ ID NO:22) and 5′-GGGGTCTGCTCTCCA-3′ (SEQ ID NO:23). In a related aspect, the invention provides methods of distinguishing a Bos taurus from a Bos indicus based on one or more polymorphisms in a bovine STAT6 gene. In some embodiments, the methods comprise: determining one or more STAT6 alleles of a bovine at one or more SNP IDs selected from the group consisting of 10922, 14257, 24000 and 25999 of a bovine gene encoding STAT6, wherein: i) an “AA” genotype at SNP ID 10922 indicates that the bovine is a Bos taurus , and a “GG” genotype at SNP ID 10922 indicates that the bovine is a Bos indicus; ii) a “CC” genotype at SNP ID 14257 indicates that the bovine is a Bos taurus , and a “AA” genotype at SNP ID 14257 indicates that the bovine is a Bos indicus; iii) a “TT” genotype at SNP ID 24000 indicates that the bovine is a Bos taurus , and a “CC” genotype at SNP ID 24000 indicates that the bovine is a Bos indicus ; and iv) a “TT” genotype at SNP ID 25999 indicates that the bovine is a Bos taurus , and an “CC” genotype at SNP ID 25999 indicates that the bovine is a Bos indicus. In some embodiments, the methods of distinguishing a Bos taurus from a Bos indicus based on one or more polymorphisms in a bovine STAT6 gene comprise: a) amplifying one or more alleles of the bovine STAT6 gene using an oligonucleotide pair to form nucleic acid amplification products comprising amplified STAT6 gene polymorphism sequences; b) detecting one or more polymorphisms present in the bovine STAT6 gene at a SNP ID selected from the group consisting of 10922, 14257, 24000 and 25999; and c) analyzing the one or more polymorphisms, wherein i) an “AA” genotype at SNP ID 10922 indicates that the bovine is a Bos taurus , and a “GG” genotype at SNP ID 10922 indicates that the bovine is a Bos indicus; ii) a “CC” genotype at SNP ID 14257 indicates that the bovine is a Bos taurus , and a “AA” genotype at SNP ID 14257 indicates that the bovine is a Bos indicus; iii) a “TT” genotype at SNP ID 24000 indicates that the bovine is a Bos taurus , and a “CC” genotype at SNP ID 24000 indicates that the bovine is a Bos indicus ; and iv) a “TT” genotype at SNP ID 25999 indicates that the bovine is a Bos taurus , and an “CC” genotype at SNP ID 25999 indicates that the bovine is a Bos indicus. With respect to the embodiments of the methods of distinguishing a Bos taurus from a Bos indicus based on polymorphisms in the STAT6 gene, in some embodiments two or more polymorphisms are determined, e.g., are amplified. In some embodiments, two, three, or four polymorphisms are determined, e.g., are amplified. In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 10922, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-TGTGATGGGTTGAACTCTGC-3′ (SEQ ID NO:24) and 5′-CTGCCTCTCAAAAATTTATATATTA-3′ (SEQ ID NO:25); and a reverse primer comprising a nucleic acid sequence selected from 5′-GGGTACCTCCTATGAATATG-3′ (SEQ ID NO:26) and 5′-GGGATATGTGATTTCAACATA-3′ (SEQ ID NO:27). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 14257, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-GGGCCTCTGACTACCAATGT-3′ (SEQ ID NO:9); 5′-TTTTTCCACACACCCCATCC-3′ (SEQ ID NO:28); and 5′-GGGACGTGTTAAGGC-3′ (SEQ ID NO:29); and a reverse primer comprising a nucleic acid sequence selected from 5′-CCACACCCTTGAAGAGGAAC-3′ (SEQ ID NO:10); 5′-ACTTCCCCCCAACCCAGAG-3′ (SEQ ID NO:30) and 5′-TTGCCCTCCTTCCCC-3′ (SEQ ID NO:31). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 14257, and the oligonucleotide pair comprises forward primer 5′-GGGCCTCTGACTACCAATGT-3′ (SEQ ID NO:9) and reverse primer 5′-CCACACCCTTGAAGAGGAAC-3′ (SEQ ID NO:10). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 24000, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-TCATTTCCCTGCTTCTGGAC-3′ (SEQ ID NO:32) and 5′-CCATCATCCATGCTCACCTTTTC-3′ (SEQ ID NO:33); and a reverse primer comprising a nucleic acid sequence selected from 5′-ATGGAATGCTTCCGGGTTAG-3′ (SEQ ID NO:34) and 5′-AGGGAGGAAGGGAGCT-3′ (SEQ ID NO:35). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 25999, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-CCTCAGGATCATGCTGTGTC-3′ (SEQ ID NO:36) and 5′-CCCTTGCTCTGCTCAGA-3′ (SEQ ID NO:37); and a reverse primer comprising a nucleic acid sequence selected from 5′-TGGTTCAGGCAGCTGTCTTC-3′ (SEQ ID NO:38) and 5′-TTCTGCCATGGTCAC-3′ (SEQ ID NO:39). In some embodiments, the polymorphism detected is a restriction fragment length polymorphism. In some embodiments, the amplification reaction is selected from the group consisting of polymerase chain reaction (PCR), strand displacement amplification (SDA), nucleic acid sequence based amplification (NASBA), rolling circle amplification (RCA), T7 polymerase mediated amplification, T3 polymerase mediated amplification and SP6 polymerase mediated amplification. In some embodiments, the bovine STAT6 gene shares at least 95% sequence identity to SEQ ID NO:1 or the complement thereof. In some embodiments, the SNP ID 10922 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:5. In some embodiments, the SNP ID 14257 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:6. In some embodiments, the SNP ID 24000 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:7. In some embodiments, SNP ID 25999 of the gene encoding STAT6 is within a nucleic acid sequence having at least 95% sequence identity to a nucleic acid sequence of SEQ ID NO:8. In a related aspect, the invention provides isolated polynucleotides for distinguishing the STAT6 SNP IDs 10922, 14257, 14636, 16084, 19597, 24000 and 25999. In some embodiments, the isolated polynucleotides distinguish STAT6 alleles at SNP ID 14257. In some embodiments, the isolated polynucleotide is SEQ ID NO:9. In some embodiments, the isolated polynucleotide is SEQ ID NO:10. Definitions Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature used herein and the laboratory procedures in cell culture, molecular genetics, organic chemistry and nucleic acid chemistry and hybridization described below are those well known and commonly employed in the art. Standard techniques are used for nucleic acid and peptide synthesis. Generally, enzymatic reactions and purification steps are performed according to the manufacturer's specifications. The techniques and procedures are generally performed according to conventional methods in the art and various general references (see generally, Sambrook et al. MOLECULAR CLONING: A LABORATORY MANUAL, 3rd ed. (2001) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. and Ausubel, ed., Current Protocols in Molecular Biology, 1990-2008, John Wiley Interscience), which are provided throughout this document. The nomenclature used herein and the laboratory procedures in analytical chemistry, and organic synthetic described below are those well known and commonly employed in the art. Standard techniques, or modifications thereof, are used for chemical syntheses and chemical analyses. STAT6 refers to nucleic acids and polypeptide polymorphic variants (including single nucleotide polymorphisms involving displacement, insertion, or deletion of a single nucleotide that may or may not lead to a change in an encoded polypeptide sequence), alleles, mutants, and interspecies homologs that: (1) have an amino acid sequence that has greater than about 90% amino acid sequence identity, for example, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% or greater amino acid sequence identity, preferably over a region of at least about 25, 50, 100, 200, 500, 1000, or more amino acids, or over the full-length, to an amino acid sequence encoded by a STAT6 nucleic acid (see, e.g., SEQ ID NO:1 and GenBank Accession Nos. AB038383 ( Bos taurus ); NC — 009149 ( Equus caballus ); BV726713 ( Sus scrofa ); EU439612.1 ( Canis lupus ); NM — 001012930 ( Gallus gallus )) or to an amino acid sequence of a STAT6 polypeptide (e.g., GenBank Accession Nos. BAA96475 ( Bos taurus ); ACA21821 ( Canis lupus ); and NP — 001012948 ( Gallus gallus ); (2) bind to antibodies, e.g., polyclonal antibodies, raised against an immunogen comprising an amino acid sequence of a STAT6 polypeptide (e.g., encoded by a nucleic acid sequence of SEQ ID NO:1 or a nucleic acid of GenBank Accession Nos. AB038383; NC — 009149; BV726713; EU439612.1; and NM — 001012930; or an amino acid sequence of GenBank Accession Nos. BAA96475; ACA21821; and NP — 001012948), and conservatively modified variants thereof, (3) specifically hybridize under stringent hybridization conditions to an anti-sense strand corresponding to a nucleic acid sequence encoding a STAT6 protein, and conservatively modified variants thereof, (4) have a nucleic acid sequence that has greater than about 95%, preferably greater than about 96%, 97%, 98%, 99%, or higher nucleotide sequence identity, preferably over a region of at least about 25, 50, 100, 200, 500, 1000, or more nucleotides, or over the full-length, to a STAT6 nucleic acid. STAT6 nucleic acids include polynucleotides comprising the SNPs described herein. Positions within the STAT6 genomic nucleic acid sequence can be counted, for example, from nucleotide 1 of SEQ ID NO:1, from position 10801 of the bovine STAT6 sequence in FIG. 1 , in reference to the adenosine nucleotide of the ATG start codon, or alternatively, in reference to the intron or exon in which the SNP resides. A STAT6 polynucleotide or polypeptide sequence is typically from a domesticated livestock animal, for example, a bovine, ovine, equine, porcine or gallus. The nucleic acids and proteins of the invention include both naturally occurring or recombinant molecules. The STAT6 genomic nucleic acid sequence is provided as SEQ ID NO:1, and also published as ENSEMBL accession number ENSBTAG00000006335 (which correlates to positions 17,194-26,693 of the STAT6 gene as defined in FIG. 1 ). As used herein, a “STAT6 gene” will have a nucleic acid sequence that has greater than about 95%, preferably greater than about 96%, 97%, 98%, 99%, or higher nucleotide sequence identity, preferably over a region of at least about 500, 1000, 2000, 3000, 50000 or more nucleotides, or over the full-length, to a STAT6 genomic nucleic acid, for example, SEQ ID NO:1 or ENSBTAG00000006335. The term “livestock animal” refers to any breed or population of animal kept by humans for a useful, commercial purpose. As used herein, a livestock animal can be mammal or avian. Generally, the livestock animal is an agricultural mammal, for example, bovine, equine, ovine, porcine. Livestock animals raised for the production of meat find use with the present invention, for example, beef cattle, pigs, goats, sheep, bison, chickens, turkeys, etc. The livestock animals can be in all stages of development, including embryonic, fetal, neonate, yearling, juvenile and adult stages. The term “bovine” refers to a domesticated (purebred or crossbreeds) or wild mammal that is a Bovinae, for example, of the genera Bos (e.g., cattle or oxen) or Bison (e.g., American buffalo). Exemplary mammals of the genus Bos include without limitation Bos taurus, Bos bovis, Bos frontalis (gayal), Bos gaurus (gaur), Bos grunniens (domestic yak), Bos grunniens x Bos taurus (dzo), Bos indicus (zebu cattle), Bos indicus gudali (Gudali zebu), Bos indicus x Bos taurus (hybrid cattle), Bos javanicus (banteng), Bos primigenius (aurochs), and Bos sauveli (kouprey). Bos species for the production of meat products, e.g., beef cattle are of use in the present invention. Exemplary breeds of Bos without limitation Black Angus, Red Angus, Horned Hereford, Polled Hereford, Charolais, Simmental, Limousine, Chianina, Brahman, Santa Gertrudis, and Wagyu. Other breeds of beef cattle of use are listed in Tables 1 and 2, infra. The term “carcass traits” refers to traits of an animal's carcass determined after the animal has been slaughtered. The term “feedlot traits” refers to traits of a live animal during the time period it is resident in a feedlot. The terms “nucleic acid” and “polynucleotide” are used interchangeably herein to refer to deoxyribonucleotides or ribonucleotides and polymers thereof in either single- or double-stranded form. The term encompasses nucleic acids containing known nucleotide analogs or modified backbone residues or linkages, which are synthetic, naturally occurring, and non-naturally occurring, which have similar binding properties as the reference nucleic acid, and which are metabolized in a manner similar to the reference nucleotides. Examples of such analogs include, without limitation, phosphorothioates, phosphoramidates, methyl phosphonates, chiral-methyl phosphonates, 2-O-methyl ribonucleotides, peptide-nucleic acids (PNAs). Unless otherwise indicated, a particular nucleic acid sequence also encompasses conservatively modified variants thereof (e.g., degenerate codon substitutions) and complementary sequences, as well as the sequence explicitly indicated. Specifically, degenerate codon substitutions may be achieved by generating sequences in which the third position of one or more selected (or all) codons is substituted with mixed-base and/or deoxyinosine residues (Batzer et al., Nucleic Acid Res. 19:5081 (1991); Ohtsuka et al., J. Biol. Chem. 260:2605-2608 (1985); Rossolini et al., Mol. Cell. Probes 8:91-98 (1994)). The term nucleic acid is used interchangeably with gene, cDNA, mRNA, oligonucleotide, and polynucleotide. A “single nucleotide polymorphism” or “SNP” refers to polynucleotide that differs from another polynucleotide by a single nucleotide exchange. For example, without limitation, exchanging one A for one C, G or T in the entire sequence of polynucleotide constitutes a SNP. Of course, it is possible to have more than one SNP in a particular polynucleotide. For example, at one locus in a polynucleotide, a C may be exchanged for a T, at another locus a G may be exchanged for an A and so on. When referring to SNPs, the polynucleotide is most often DNA and the SNP is one that usually results in a change in the genotype that is associated with a corresponding change in phenotype of the organism in which the SNP occurs. A “variant” is a difference in the nucleotide sequence among related polynucleotides. The difference may be the deletion of one or more nucleotides from the sequence of one polynucleotide compared to the sequence of a related polynucleotide, the addition of one or more nucleotides or the substitution of one nucleotide for another. The terms “mutation,” “polymorphism” and “variant” are used interchangeably herein to describe such variants. As used herein, the term “variant” in the singular is to be construed to include multiple variances; i.e., two or more nucleotide additions, deletions and/or substitutions in the same polynucleotide. A “point mutation” refers to a single substitution of one nucleotide for another. A nucleic acid “that distinguishes” as used herein refers to a polynucleotide(s) that (1) specifically hybridizes under stringent hybridization conditions to an anti-sense strand corresponding to a nucleic acid sequence encoding a STAT6 protein, and conservatively modified variants thereof, or (2) has a nucleic acid sequence that has greater than about 80%, 85%, 90%, 95%, preferably greater than about 96%, 97%, 98%, 99%, or higher nucleotide sequence identity, preferably over a region of at least about 25, 50, 100, 200, 500, 1000, or more nucleotides, to a STAT6 nucleic acid (e.g., a sequence as set forth in SEQ ID NO:1, or complements or a subsequences thereof. A nucleic acid that distinguishes a first STAT6 polymorphism from a second STAT6 polymorphism at the same position in the STAT6 sequence will allow for polynucleotide extension and amplification after annealing to a STAT6 polynucleotide comprising the first polymorphism, but will not allow for will not allow for polynucleotide extension or amplification after annealing to a STAT6 polynucleotide comprising the second polymorphism. In other embodiments, a nucleic acid that distinguishes a first STAT6 polymorphism from a second STAT6 polymorphism at the same position in the STAT6 sequence will hybridize to a STAT6 polynucleotide comprising the first polymorphism but will not hybridize to a STAT6 polynucleotide comprising the second polymorphism. The phrase “stringent hybridization conditions” refers to conditions under which a probe will hybridize to its target subsequence, typically in a complex mixture of nucleic acid, but to no other sequences. Stringent conditions are sequence-dependent and will be different in different circumstances. Longer sequences hybridize specifically at higher temperatures. An extensive guide to the hybridization of nucleic acids is found in Tijssen, Techniques in Biochemistry and Molecular Biology—Hybridization with Nucleic Probes, “Overview of principles of hybridization and the strategy of nucleic acid assays” (1993). Generally, stringent conditions are selected to be about 5-10° C. lower than the thermal melting point I for the specific sequence at a defined ionic strength pH. The Tm is the temperature (under defined ionic strength, pH, and nucleic concentration) at which 50% of the probes complementary to the target hybridize to the target sequence at equilibrium (as the target sequences are present in excess, at Tm, 50% of the probes are occupied at equilibrium). Stringent conditions will be those in which the salt concentration is less than about 1.0 M sodium ion, typically about 0.01 to 1.0 M sodium ion concentration (or other salts) at pH 7.0 to 8.3 and the temperature is at least about 30° C. for short probes (e.g., 10 to 50 nucleotides) and at least about 60° C. for long probes (e.g., greater than 50 nucleotides). Stringent conditions may also be achieved with the addition of destabilizing agents such as formamide. For selective or specific hybridization, a positive signal is at least two times background, optionally 10 times background hybridization. Exemplary stringent hybridization conditions can be as following: 50% formamide, 5×SSC, and 1% SDS, incubating at 42° C., or, 5×SSC, 1% SDS, incubating at 65° C., with wash in 0.2×SSC, and 0.1% SDS at 65° C. Nucleic acids that do not hybridize to each other under stringent conditions are still substantially identical if the polypeptides which they encode are substantially identical. This occurs, for example, when a copy of a nucleic acid is created using the maximum codon degeneracy permitted by the genetic code. In such cases, the nucleic acids typically hybridize under moderately stringent hybridization conditions. Exemplary “moderately stringent hybridization conditions” include a hybridization in a buffer of 40% formamide, 1 M NaCl, 1% SDS at 37° C., and a wash in 1×SSC at 45° C. A positive hybridization is at least twice background. Those of ordinary skill will readily recognize that alternative hybridization and wash conditions can be utilized to provide conditions of similar stringency. The phrase “selectively (or specifically) hybridizes to” refers to the binding, duplexing, or hybridizing of a molecule only to a particular nucleotide sequence under stringent hybridization conditions when that sequence is present in a complex mixture (e.g., total cellular or library DNA or RNA). The terms “isolated,” “purified,” or “biologically pure” refer to material that is substantially or essentially free from components that normally accompany it as found in its native state. Purity and homogeneity are typically determined using analytical chemistry techniques such as polyacrylamide gel electrophoresis or high performance liquid chromatography. A protein that is the predominant species present in a preparation is substantially purified. In particular, an isolated STAT6 nucleic acid is separated from open reading frames that flank the STAT6 gene and encode proteins other than STAT6. The term “purified” denotes that a nucleic acid or protein gives rise to essentially one band in an electrophoretic gel. Particularly, it means that the nucleic acid or protein is at least 85% pure, more preferably at least 95% pure, and most preferably at least 99% pure. The terms “polypeptide,” “peptide” and “protein” are used interchangeably herein to refer to a polymer of amino acid residues. The terms apply to amino acid polymers in which one or more amino acid residue is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymer. The term “amino acid” refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those amino acids that are later modified, e.g., hydroxyproline, α-carboxyglutamate, and O-phosphoserine. Amino acid analogs refers to compounds that have the same basic chemical structure as a naturally occurring amino acid, i.e., an a carbon that is bound to a hydrogen, a carboxyl group, an amino group, and an R group, e.g., homoserine, norleucine, methionine sulfoxide, methionine methyl sulfonium. Such analogs have modified R groups (e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as a naturally occurring amino acid. Amino acid mimetics refers to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that functions in a manner similar to a naturally occurring amino acid. Amino acids may be referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Biochemical Nomenclature Commission. Nucleotides, likewise, may be referred to by their commonly accepted single-letter codes. “Conservatively modified variants” applies to both amino acid and nucleic acid sequences. With respect to particular nucleic acid sequences, conservatively modified variants refers to those nucleic acids which encode identical or essentially identical amino acid sequences, or where the nucleic acid does not encode an amino acid sequence, to essentially identical sequences. Because of the degeneracy of the genetic code, a large number of functionally identical nucleic acids encode any given protein. For instance, the codons GCA, GCC, GCG and GCU all encode the amino acid alanine. Thus, at every position where an alanine is specified by a codon, the codon can be altered to any of the corresponding codons described without altering the encoded polypeptide. Such nucleic acid variations are “silent variations,” which are one species of conservatively modified variations. Every nucleic acid sequence herein which encodes a polypeptide also describes every possible silent variation of the nucleic acid. One of skill will recognize that each codon in a nucleic acid (except AUG, which is ordinarily the only codon for methionine, and TGG, which is ordinarily the only codon for tryptophan) can be modified to yield a functionally identical molecule. Accordingly, each silent variation of a nucleic acid which encodes a polypeptide is implicit in each described sequence. As to amino acid sequences, one of skill will recognize that individual substitutions, deletions or additions to a nucleic acid, peptide, polypeptide, or protein sequence which alters, adds or deletes a single amino acid or a small percentage of amino acids in the encoded sequence is a “conservatively modified variant” where the alteration results in the substitution of an amino acid with a chemically similar amino acid. Conservative substitution tables providing functionally similar amino acids are well known in the art. Such conservatively modified variants are in addition to and do not exclude polymorphic variants, interspecies homologs, and alleles of the invention. The following eight groups each contain amino acids that are conservative substitutions for one another: 1) Alanine (A), Glycine (G); 2) Aspartic acid (D), Glutamic acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine I, Lysine (K); 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); 6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W); 7) Serine (S), Threonine (T); and 8) Cysteine (C), Methionine (M) (see, e.g., Creighton, Proteins (1984)). The terms “identical” or percent “identity,” in the context of two or more nucleic acids or polypeptide sequences, refer to two or more sequences or subsequences that are the same or have a specified percentage of amino acid residues or nucleotides that are the same (i.e., share at least about 80% identity, for example, at least about 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identity over a specified region to a reference sequence, e.g., SEQ ID NO:1 or a polypeptide encoded by SEQ ID NO:1), when compared and aligned for maximum correspondence over a comparison window, or designated region as measured using one of the following sequence comparison algorithms or by manual alignment and visual inspection. Such sequences are then said to be “substantially identical.” This definition also refers to the compliment of a test sequence. Preferably, the identity exists over a region that is at least about 25 amino acids or nucleotides in length, for example, over a region that is 50-100 amino acids or nucleotides in length, or over the full-length of a reference sequence. For sequence comparison, typically one sequence acts as a reference sequence, to which test sequences are compared. When using a sequence comparison algorithm, test and reference sequences are entered into a computer, subsequence coordinates are designated, if necessary, and sequence algorithm program parameters are designated. Default program parameters can be used, or alternative parameters can be designated. The sequence comparison algorithm then calculates the percent sequence identities for the test sequences relative to the reference sequence, based on the program parameters. For sequence comparison of nucleic acids and proteins to STAT6 nucleic acids and proteins, the BLAST and BLAST 2.0 algorithms and the default parameters discussed below are used. A “comparison window”, as used herein, includes reference to a segment of any one of the number of contiguous positions selected from the group consisting of from 20 to 600, usually about 50 to about 200, more usually about 100 to about 150 in which a sequence may be compared to a reference sequence of the same number of contiguous positions after the two sequences are optimally aligned. Methods of alignment of sequences for comparison are well-known in the art. Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith & Waterman, Adv. Appl. Math. 2:482 (1981), by the homology alignment algorithm of Needleman & Wunsch, J. Mol. Biol. 48:443 (1970), by the search for similarity method of Pearson & Lipman, Proc. Nat'l. Acad. Sci. USA 85:2444 (1988), by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis.), or by manual alignment and visual inspection (see, e.g., Current Protocols in Molecular Biology (Ausubel et al., eds. 1995 supplement)). Examples of algorithms that are suitable for determining percent sequence identity and sequence similarity are the BLAST and BLAST 2.0 algorithms, which are described in Altschul et al. (1990) J. Mol. Biol. 215: 403-410 and Altschul et al. (1977) Nucleic Acids Res. 25: 3389-3402, respectively. Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information (on the worldwide web at ncbi.nlm.nih.gov/). The algorithm involves first identifying high scoring sequence pairs (HSPs) by identifying short words of length W in the query sequence, which either match or satisfy some positive-valued threshold score T when aligned with a word of the same length in a database sequence. T is referred to as the neighborhood word score threshold (Altschul et al, supra). These initial neighborhood word hits acts as seeds for initiating searches to find longer HSPs containing them. The word hits are then extended in both directions along each sequence for as far as the cumulative alignment score can be increased. Cumulative scores are calculated using, for nucleotide sequences, the parameters M (reward score for a pair of matching residues; always >0) and N (penalty score for mismatching residues; always <0). For amino acid sequences, a scoring matrix is used to calculate the cumulative score. Extension of the word hits in each direction are halted when: the cumulative alignment score falls off by the quantity X from its maximum achieved value; the cumulative score goes to zero or below, due to the accumulation of one or more negative-scoring residue alignments; or the end of either sequence is reached. The BLAST algorithm parameters W, T, and X determine the sensitivity and speed of the alignment. The BLASTN program (for nucleotide sequences) uses as defaults a word size (W) of 28, an expectation (E) of 10, M=1, N=−2, and a comparison of both strands. For amino acid sequences, the BLASTP program uses as defaults a word size (W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (see Henikoff& Henikoff, Proc. Natl. Acad. Sci. USA 89:10915 (1989)). The BLAST algorithm also performs a statistical analysis of the similarity between two sequences (see, e.g., Karlin & Altschul, Proc. Nat'l. Acad. Sci. USA 90:5873-5787 (1993)). One measure of similarity provided by the BLAST algorithm is the smallest sum probability (P(N)), which provides an indication of the probability by which a match between two nucleotide or amino acid sequences would occur by chance. For example, a nucleic acid is considered similar to a reference sequence if the smallest sum probability in a comparison of the test nucleic acid to the reference nucleic acid is less than about 0.2, more preferably less than about 0.01, and most preferably less than about 0.001. An indication that two nucleic acid sequences or polypeptides are substantially identical is that the polypeptide encoded by the first nucleic acid is immunologically cross reactive with the antibodies raised against the polypeptide encoded by the second nucleic acid, as described below. Thus, a polypeptide is typically substantially identical to a second polypeptide, for example, where the two peptides differ only by conservative substitutions. Another indication that two nucleic acid sequences are substantially identical is that the two molecules or their complements hybridize to each other under stringent conditions, as described below. Yet another indication that two nucleic acid sequences are substantially identical is that the same primers can be used to amplify the sequence. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 1I illustrate the annotated sequence of the bovine STAT6 genomic sequence (SEQ ID NO:1). The positions of SNP IDs 10922, 14257, 14636, 16084, 19597, 24000 and 25999 and exons 1-21 are identified. Each exon is labeled with a letter “E” with the number of the exon, and is marked with a line above the corresponding sequence (“˜˜˜˜˜˜”). FIGS. 2A to 2B illustrate a multiple sequence alignment of the STAT6 protein sequence, highlighting the high degree of conservation between bovine (SEQ ID NO:40), equine (SEQ ID NO:41), canine (SEQ ID NO:42), human (SEQ ID NO:43) and murine (SEQ ID NO:44) STAT6 amino acid sequences. FIG. 3 illustrates a representative result of a PCR/RFLP genotyping assay for STAT6 SNP ID 14257. Detecting polymorphisms at SNP ID 14257 differentiates between Bos taurus and Bos indicus species. DETAILED DESCRIPTION 1. Introduction Single nucleotide polymorphisms (SNPs) can provide a useful way in which to distinguish different alleles of a gene. Furthermore, when the presence of a SNP can be associated with a specific phenotype, the SNP operates as a powerful marker and can be used to predict phenotypic outcomes based on an animal's genotypic makeup. The present invention relates to methods of managing livestock animals, for example, cattle, sheep, goats, horses and pigs, and taking advantage of genetic factors that affect an animal's fat distribution and disposition. By identifying animals with a particular genotype, with respect to herein described SNP alleles, it is possible to identify animals that will display phenotypes associated with carcass traits including back fat, carcass weight, and cutability; and feedlot traits including average daily gain, days on feed and dry matter intake, as compared to animals lacking the desired genotype. In particular, the present invention relates to methods for establishing the genetically determined predispositions of individual livestock animals, for example, cattle, sheep, goats, horses and pigs, within a group of such animals, to meet particular desired characteristics with respect to carcass and feedlot traits, based on the association of specific STAT6 alleles with statistically correlated carcass and feedlot phenotypes. The present invention provides methods for analyzing the genotype of animals with respect to the STAT6 gene, and using the genotype information to select animals with desired traits related to carcass and feedlot traits. Such knowledge further permits producers to charge a premium for the more desirable phenotype, and permits breeders to selectively breed animals for genotypes that will result in the most desirable phenotypes. The present invention is based in part on the unexpected discovery that the location of ETH10 is within the first exon of STAT6 (e.g., positions 13,805-13,844 of the bovine STAT6 genomic nucleic acid sequence in FIG. 1 ). Using the bovine whole genome radiation hybrid panel, it was demonstrated that STAT6 mapped 0.3 cR from ETH10 with a LOD score of 20.4. Available EST sequences were assembled and part of the bovine STAT6 gene from cDNA was sequenced, confirming that the location of ETH 10 is indeed within the first exon of STAT6. The present invention provides a biological explanation for the association between the amount of marbling (the size and number of adipocytes within muscle tissue) and genotype at ETH10 and/or STAT6 alleles. In particular, three single nucleotide polymorphisms (SNPs) within the STAT6 gene, i.e., SNP ID 14636, SNP ID 16084 and SNP ID 19597, have been identified that are statistically correlated with economically important feedlot and carcass traits in livestock animals, for example, bovines, for example, Bos taurus . In addition, four SNPS within the STAT6 gene, i.e., SNP ID 10922, SNP ID 14257, SNP ID 24000, and SNP ID 25999, have been identified that are fixed in Bos taurus and Bos indicus , and are useful for genetically distinguishing these two Bos species that are oftentimes phenotypically indistinguishable. 2. Methods of Determining Desirable Traits in Livestock Animals by Determining SNPs in the STAT6 Gene a. Livestock Animals The present invention is useful for identifying desired phenotypes in a livestock animal based on its STAT6 genotype, particularly at SNP IDs 16084, 19597 and 14636. The livestock animal can be any animal that is raised commercially for meat production, for example, beef, pork, mutton, lamb or poultry. Oftentimes the livestock animal is a mammal. In some embodiments, the livestock animal is a bovine, ovine, equine, or porcine. In some embodiments, the livestock animal is a bovine, for example, of the genus Bos , for example, beef cattle. The STAT6 genomic nucleic acid sequence, protein-encoding nucleic acid sequence (i.e., mRNA or cDNA), and amino acid sequence is conserved amongst mammalian species. The amino acid alignment in FIG. 2 shows that the bovine STAT6 protein shares about 93% amino acid sequence identity with the STAT6 protein of horse and dog, and about 92% amino acid sequence identity with the murine STAT6 protein. The bovine STAT6-encoding nucleic acid sequence shares about 95% nucleic acid sequence identity with the STAT6-encoding nucleic acid sequence of horse and about 93% nucleic acid sequence identity with the STAT6-encoding nucleic acid sequence of dog. b. Biological Samples The methods of the present invention involve taking a biological sample comprising genomic DNA from the animal to be tested. The biological sample can be from solid tissue or a biological fluid that contains a nucleic acid comprising a single nucleotide polymorphism (SNP) described herein, e.g., a nucleic acid comprising a STAT6 gene. The biological sample can be tested by the methods described herein and include body fluids including whole blood, serum, plasma, cerebrospinal fluid, urine, lymph fluids, semen, and various external secretions of the respiratory, intestinal and genitourinary tracts, tears, saliva, milk, white blood cells, myelomas, and the like; and biological fluids such as cell extracts, cell culture supernatants; fixed tissue specimens; and fixed cell specimens. Biological samples can also be from solid tissue, including hair bulb, skin, biopsy or autopsy samples or frozen sections taken for histologic purposes. These samples are well known in the art. A biological sample is obtained from any livestock animal to be tested for STAT6 SNPs as described herein, including, e.g., a beef cow. A biological sample can be suspended or dissolved in liquid materials such as buffers, extractants, solvents and the like. c. SNPs in STAT6 Correlated with Desirable Traits Livestock mammals, including bovines, ovines, equines and porcines, are diploid organisms possessing pairs of homologous chromosomes. Thus, at a typical genetic locus, an animal has three possible genotypes that can result from the combining of two different alleles (e.g. A and B). The animal may be homozygous for one or another allele, or heterozygous, possessing one of each of the two possible alleles (e.g. AA, BB or AB). The STAT6 SNP IDs statistically correlated with desirable carcass and feedlot phenotypes include SNP ID 14636, SNP ID 16084 and SNP ID 19597. STAT6 SNP ID 14636 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 14636 is positioned at nucleotide 14989 of the sequence depicted in FIG. 1 , or at position 4189 of SEQ ID NO:1. SNP ID 14636 is also positioned at nucleotide 656 of intron 1 of the STAT6 sequence depicted in FIG. 1 . A homozygous “CC” genotype at STAT6 SNP ID 14636 is statistically correlated with the carcass and feedlot phenotypes of increased back fat rate, fewer days on feed, and increased average daily gain. A homozygous “GG” genotype at STAT6 SNP ID 14636 is statistically correlated with the carcass and feedlot phenotypes of decreased back fat rate, greater number of days on feed, and decreased average daily gain. See, Table 4. STAT6 SNP ID 16084 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 16084 is positioned at nucleotide 16437 of the sequence depicted in FIG. 1 , or at position 5637 of SEQ ID NO:1. SNP ID 16084 is also positioned at nucleotide 2104 of intron 1 of the STAT6 sequence depicted in FIG. 1 . A homozygous “AA” genotype at STAT6 SNP ID 16084 is statistically correlated with the carcass phenotypes of increased back fat, increased calculated yield grade and decreased cutability. A homozygous “CC” genotype at STAT6 SNP ID 16084 is statistically correlated with the carcass phenotypes of decreased back fat, decreased calculated yield grade and increased cutability. See, Table 4. STAT6 SNP ID 19597 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 19597 is positioned at nucleotide 19950 of the sequence depicted in FIG. 1 , or at position 9150 of SEQ ID NO:1. SNP ID 19597 is also positioned at nucleotide 20 of intron 8 of the STAT6 sequence depicted in FIG. 1 . A homozygous “AA” genotype at STAT6 SNP ID 19597 is statistically correlated with the carcass and feedlot phenotypes of increased hot carcass weight, increased dry matter intake and fewer days on feed. A homozygous “GG” genotype at STAT6 SNP ID 19597 is statistically correlated with the carcass and feedlot phenotypes of decreased hot carcass weight, decreased dry matter intake and greater number of days on feed. See, Table 4. d. Carcass Traits Carcass traits statistically correlated with the STAT6 SNPs identified in the present inventions include back fat thickness (BFAT), calculated yield grade (CALYG), cutability (CUT) and hot carcass weight (HCW). Back Fat Thickness (BFAT). Back fat thickness is expressed in tenths of an inch of the fat thickness at the 12th rib (as measured between the 12th and 13th ribs) of an animal's carcass. This is the amount of fat covering the ribeye. Hot Carcass Weight (HCW). Hot carcass weight is the weight expressed in pounds of an animal after slaughter. Hot carcass weight is obtained immediately after dressing (i.e., the viscera and hide are removed) and prior to carcass chilling. Calculated Yield Grade (CALYG) refers to a calculated value that includes back fat thickness (BFAT), ribeye area (REA), hot carcass weight (HCW), and kidney, pelvic, and heart fat percentage (KPH). This value is calculated using any of several known equations. Below are provided the calculated yield grade equations used by the USDA and by Iowa State University. CalYG= 2.46+2.49( B FAT)−0.13( REA )+0.0002(HCW)+0.115( KPH ) (Reference: 2000 Beef Research Report—Iowa State University—A. S. Leaflet R1730). CalYG= 2.5+2.5( B FAT)−0.32( REA )+0.0038(HCW)+0.2( KPH ) (USDA yield equation) Yield grades are used to identify carcasses that differ in yield of boneless, closely trimmed retail cuts from the round, loin, rib, and chuck. Yield grades range from 1 through 5. A yield grade 5 carcass would have the lowest cutability and would be characterized as light muscled and/or excessively fat. Accordingly, a lower calculated yield grade value is more desirable and a higher yield grade value is less desirable. Because current yield grades are too broad to clearly define value differences in retail yield, yield grades 2 and 3 have been divided into 2A and 2B and 3A and 3B respectively. Yield grades 2.0 to 2.5 are classified 2A and 2.5 to 3.0 are classified 2B. Similarly, yield grades 3.0 to 3.5 are classified 3A and 3.5 to 4.0 are classified 3B. Combining quality grade with yield grade more clearly defines carcass value than when quality grade alone is used. See, e.g., the worldwide web at caf.wvu.edu/˜forage/yieldgrd/yieldgrades.htm. Carcass traits considered in a calculated yield grade equation, are described, for example, on the worldwide web at ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=19. As discussed above, external back fat thickness is measured in tenths of an inch and is the amount of fat covering the ribeye at the point of the 12th and 13th ribs. Hot carcass weight and REA work together as an indication of overall muscling of the animal. A heavy carcass is expected to have more total muscle than a lighter weight carcass. If a carcass does not have as much muscling as you would expect from an average carcass of that weight, it makes the yield grade less desirable. If a carcass has more muscling than average for that weight, it improves the yield grade. Percentage of KPH measures the amount of internal fat. All animals have some fat surrounding their internal organs such as the liver or heart. The less of this fat a carcass has, the better for the yield grade. The amount of KPH is expressed as a percentage of carcass weight. For example, an 800 pound carcass with 2.5% KPH has 20 pounds of internal fat. External adjusted fat thickness (more fat=less desirable yield grade) Hot carcass weight (heavier weight=less desirable yield grade) Percentage of kidney, pelvic and heart fat (more fat=less desirable yield grade) Ribeye area (larger ribeye=more desirable yield grade) Cutability. The percent yield of the carcass is also called the cutability of the carcass. The cutability of the carcass is calculated from the following formula: % retail cuts=51.34−(5.78×Adj. Fat thickness)−(0.0088×hot carcass weight)−(0.462 ×KPH )+(0.740×ribeye area) Beef yield grades provide an estimate of how much lean, edible meat the carcass will produce. Yield grades are 1, 2, 3, 4 and 5, with 1 being a lean, heavy muscled carcass that will yield a high percentage of lean meat, and 5 being an overly fat, light muscled carcass. If all the bones and fat are removed from the major portions of the carcass (the rounds, loins, ribs and chucks), roughly 53-55% of a Yield Grade 1 carcass will become saleable, retail meat. From a Yield Grade 1, 800 pound carcass, you would expect approximately 430 lbs of meat. From an 800 pound, Yield Grade 5 carcass, you could expect a 43-45% yield, or about 350 lbs of meat. See, e.g., the worldwide web at ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=19. e. Feedlot Traits Feedlot traits statistically correlated with the STAT6 SNPs identified in the present inventions include dry matter intake (DMI), days on feed (DOF), average daily gain, and back fat rate (BFAT RATE). These are arbitrary measurements from the time animals arrive in the feedlot until they are slaughtered. The measurements are used to recharge owners that subcontract feeding their animals in the feedlot, and or to calculate the economic efficiency of feeding different lots of animals. Days on feed (DOF) is measured in days fed in the feedlot from the time the animals enter the feedlot until they are slaughtered approximately when they have 0.4-0.5 in back fat or close to a Choice grade. Average daily gain (ADG) is the average daily weight gain of the animal in pounds in the feedlot measured from the time of arrival to the feedlot until the animal is slaughtered. Dry matter intake (DMI) is the amount of feed consumed in dry matter basis (pounds) by an animal in the feedlot measured from the time of arrival to the feedlot until the animal is slaughtered. Back Fat Rate (BFAT RATE) is the rate of back fat accumulation on an animal measured on a daily basis. Back fat can be measured on the animal using any method known in the art, including for example, ultrasound techniques. f. Detection of SNPs The STAT6 SNPs can be detected using any methods known in art, including without limitation amplification, sequencing and hybridization techniques. Detection techniques for evaluating nucleic acids for the presence of a single base change involve procedures well known in the field of molecular genetics. Methods for amplifying nucleic acids find use in carrying out the present methods. Ample guidance for performing the methods is provided in the art. Exemplary references include manuals such as PCR Technology: PRINCIPLES AND APPLICATIONS FOR DNA AMPLIFICATION (ed. H. A. Erlich, Freeman Press, NY, N.Y., 1992); PCR PROTOCOLS: A GUIDE TO METHODS AND APPLICATIONS (eds. Innis, et al., Academic Press, San Diego, Calif., 1990); CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, Ausubel, 1990-2008, including supplemental updates; Sambrook & Russell, Molecular Cloning, A Laboratory Manual (3rd Ed, 2001). According to one aspect of the present invention, there is provided a method for distinguishing livestock animals e.g., bovines having a STAT6 gene polymorphism. The method comprises the steps of first isolating a genomic DNA sample from a livestock animal, e.g., bovine, and then detecting, e.g., amplifying a region of the STAT6 gene using an oligonucleotide pair to form nucleic acid amplification products of STAT6 gene polymorphism sequences. Amplification can be by any of a number of methods known to those skilled in the art including PCR, and the invention is intended to encompass any suitable methods of DNA amplification. A number of DNA amplification techniques are suitable for use with the present invention. Conveniently such amplification techniques include methods such as polymerase chain reaction (PCR), strand displacement amplification (SDA), nucleic acid sequence based amplification (NASBA), rolling circle amplification, T7 polymerase mediated amplification, T3 polymerase mediated amplification and SP6 polymerase mediated amplification. The precise method of DNA amplification is not intended to be limiting, and other methods not listed here will be apparent to those skilled in the art and their use is within the scope of the invention. In some embodiments, the polymerase chain reaction (PCR) process is used (see, e.g., U.S. Pat. Nos. 4,683,195 and 4,683,202. PCR involves the use of a thermostable DNA polymerase, known sequences as primers, and heating cycles, which separate the replicating deoxyribonucleic acid (DNA), strands and exponentially amplify a gene of interest. Any type of PCR, including quantitative PCR, RT-PCR, hot start PCR, LA-PCR, multiplex PCR, touchdown PCR, finds use. In some embodiments, real-time PCR is used. The amplification products are then analyzed in order to detect the presence or absence of at least one polymorphism in the STAT6 gene that is associated with the desired phenotypes, as discussed herein. By practicing the methods of the present invention and analyzing the amplification products it is possible to determine the genotype of individual animals with respect to the polymorphism. In some embodiments, analysis may be made by restriction fragment length polymorphism (RFLP) analysis of a PCR amplicon produced by amplification of genomic DNA with the oligonucleotide pair. In order to simplify detection of the amplification products and the restriction fragments, those of skill will appreciate that the amplified DNA will further comprise labeled moieties to permit detection of relatively small amounts of product. A variety of moieties are well known to those skilled in the art and include such labeling tags as fluorescent, bioluminescent, chemiluminescent, and radioactive or colorigenic moieties. A variety of methods of detecting the presence and restriction digestion properties of STAT6 gene amplification products are also suitable for use with the present invention. These can include methods such as gel electrophoresis, mass spectroscopy or the like. The present invention is also adapted to the use of single stranded DNA detection techniques such as fluorescence resonance energy transfer (FRET). For FRET analysis, hybridization anchor and detection probes may be used to hybridize to the amplification products. The probes sequences are selected such that in the presence of the SNP, for example, the resulting hybridization complex is more stable than if there is a G or C residue at a particular nucleotide position. By adjusting the hybridization conditions, it is therefore possible to distinguish between animals with the SNP and those without. A variety of parameters well known to those skilled in the art can be used to affect the ability of a hybridization complex to form. These include changes in temperature, ionic concentration, or the inclusion of chemical constituents like formamide that decrease complex stability. It is further possible to distinguish animals heterozygous for the SNP versus those that are homozygous for the same. The method of FRET analysis is well known to the art, and the conditions under which the presence or absence of the SNP would be detected by FRET are readily determinable. Suitable sequence methods of detection also include e.g., dideoxy sequencing-based methods and Maxam and Gilbert sequence (see, e.g., Sambrook and Russell, supra). Suitable HPLC-based analyses include, e.g., denaturing HPLC (dHPLC) as described in e.g., Premstaller and Oefner, LC-GC Europe 1-9 (July 2002); Bennet et al., BMC Genetics 2:17 (2001); Schrimi et al., Biotechniques 28(4):740 (2000); and Nairz et al., PNAS USA 99(16):10575-10580 (2002); and ion-pair reversed phase HPLC-electrospray ionization mass spectrometry (ICEMS) as described in e.g., Oberacher et al.; Hum. Mutat. 21(1):86 (2003). Other methods for characterizing single base changes in STAT6 alleles include, e.g., single base extensions (see, e.g., Kobayashi et al, Mol. Cell. Probes, 9:175-182, 1995); single-strand conformation polymorphism analysis, as described, e.g, in Orita et al., Proc. Nat. Acad. Sci. 86, 2766-2770 (1989), allele specific oligonucleotide hybridization (ASO) (e.g., Stoneking et al., Am. J. Hum. Genet. 48:70-382, 1991; Saiki et al., Nature 324, 163-166, 1986; EP 235,726; and WO 89/11548); and sequence-specific amplification or primer extension methods as described in, for example, WO 93/22456; U.S. Pat. Nos. 5,137,806; 5,595,890; 5,639,611; and U.S. Pat. No. 4,851,331; 5′-nuclease assays, as described in U.S. Pat. Nos. 5,210,015; 5,487,972; and 5,804,375; and Holland et al., 1988, Proc. Natl. Acad. Sci. USA 88:7276-7280. Methods for detecting single base changes well known in the art often entail one of several general protocols: hybridization using sequence-specific oligonucleotides, primer extension, sequence-specific ligation, sequencing, or electrophoretic separation techniques, e.g., singled-stranded conformational polymorphism (SSCP) and heteroduplex analysis. Exemplary assays include 5′ nuclease assays, template-directed dye-terminator incorporation, molecular beacon allele-specific oligonucleotide assays, single-base extension assays, and SNP scoring by real-time pyrophosphate sequences. Analysis of amplified sequences can be performed using various technologies such as microchips, fluorescence polarization assays, and matrix-assisted laser desorption ionization (MALDI) mass spectrometry. In addition to these frequently used methodologies for analysis of nucleic acid samples to detect single base changes, any method known in the art can be used to detect the presence of the STAT6 SNPs described herein. For example FRET analysis can be used as a method of detection. Conveniently, hybridization probes comprising an anchor and detection probe, the design of which art is well known to those skilled in the art of FRET analysis, are labeled with a detectable moiety, and then under suitable conditions are hybridized a STAT6 amplification product containing the site of interest in order to form a hybridization complex. A variety of parameters well known to those skilled in the art can be used to affect the ability of a hybridization complex to form. These include changes in temperature, ionic concentration, or the inclusion of chemical constituents like formamide that decrease complex stability. The presence or absence of the STAT6 SNP is then determined by the stability of the hybridization complex. The parameters affecting hybridization and FRET analysis are well known to those skilled in the art. The amplification products and hybridization probes described herein are suitable for use with FRET analysis. In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 14636, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-GCTGGTCACTCTTCCTAATC-3′ (SEQ ID NO:11) and 5′-TCTGACTTAGGGATCACCTC-3′ (SEQ ID NO:12); and a reverse primer comprising a nucleic acid sequence selected from 5′-GACCTCTATCTCTACCCTAC-3′ (SEQ ID NO:13); 5′-ACCTCTATCTCTACCCTACG-3′ (SEQ ID NO:14) and 5′-CTCTACCCTACGGGGAC-3′ (SEQ ID NO:15). In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 16084, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-TTTCCCTACTGCCCCATTGC-3′ (SEQ ID NO:16); 5′-TCAGAGAGCTTTCCCTACTG-3′ (SEQ ID NO:17); and 5′-CCTGTCTCTTACCCTCT-3′ (SEQ ID NO:18); and a reverse primer comprising the nucleic acid sequence 5′-TAATGGAGTGGGAAGAGCTG-3′ (SEQ ID NO:19). In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 19597, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-CACACTCGTCACCAGGTATG-3′ (SEQ ID NO:20) and 5′-GAGCCCCCCTGCCTG-3′ (SEQ ID NO:21); and a reverse primer comprising a nucleic acid sequence selected from 5′-AACTCTGACCCTCCTGTTTC-3′ (SEQ ID NO:22) and 5′-GGGGTCTGCTCTCCA-3′ (SEQ ID NO:23). g. Selecting Livestock Animals with Desirable Traits The present invention provides a method of selecting individual livestock animals based on the knowledge of an animal's STAT6 genotype. With respect to the SNPs described in the present invention, livestock animals with alleles at SNP IDs 14636, 16084, 19597 correlated with desirable carcass and feedlot traits can be selected. For example, a “CC” homozygous genotype at SNP ID 16084 is correlated with the carcass phenotypes of decreased back fat, increased cutability and decreased calculated yield grade. An “AA” homozygous genotype at SNP ID 16084 is correlated with the carcass phenotypes of increased back fat, decreased cutability and increased calculated yield grade. Similarly, an “AA” homozygous genotype at SNP ID 19597 is correlated with the carcass and feedlot phenotypes of an increased hot carcass weight, increased dry matter intake and fewer days on feed. A “GG” homozygous genotype at SNP ID 19597 is correlated with the carcass and feedlot phenotypes of a decreased hot carcass weight, decreased dry matter intake and greater number of days on feed. A “CC” homozygous genotype at SNP ID 14636 is correlated with the carcass and feedlot phenotypes of an increased back fat rate, increased average daily gain and fewer days on feed. A “GG” homozygous genotype at SNP ID 14636 is correlated with the carcass and feedlot phenotypes of a decreased back fat rate, decreased average daily gain and greater number of days on feed. See, Table 4. According to the methods of the present invention, a livestock animal can be selected based on its STAT6 genotype at SNP IDs 16084, 19597 and 14636. With the knowledge of the animal's STAT6 genotype one can then identify and sort animals into groups of like phenotype(s), or otherwise use the knowledge of the genotype in order to predict which animals will have the desired phenotypes, for example, decreased back fat, increased cutability, decreased calculated yield grade, increased hot carcass weight, increased dry matter intake, fewer days on feed, increased or decreased back fat rate, and increased average daily gain. Knowledge of the animal's STAT6 genotype allows a breeder to encourage breeding between animals with a desired STAT6 genotype, and to discourage breeding between animals with an undesirable STAT6 genotype. Selecting or sorting can be taken to mean placing animals in physical groupings such as pens, so that animals of like genotype are kept separate from animals of a different genotype. This would be a useful practice in the case of breeding programs where it would be desirable to produce animals of particular genotypes. For example, it may be desirable to establish herds that are homozygous “CC” at SNP ID 16084, homozygous “AA” at SNP ID 19597 and homozygous “CC” at SNP ID 14636 within the STAT6 gene, such that breeding among these animals would only produce animals with a desired STAT6 genotype. On the other hand, it may also be desirable to decrease production of animals with an undesired STAT6 genotype. Separating out animals with the desired STAT6 genotype(s) would prevent animals with an undesired STAT6 genotype from breeding with animals possessing a desired STAT6 genotype, facilitating the reproduction of animals with an increased tendency to display the desired phenotypes associated with the STAT6 alleles. Furthermore, ensuring that at least one animal in a breeding pair possesses desired STAT6 alleles allows for the frequency of the desired STAT6 alleles to be increased in the next, and subsequent generations. For example, a favorable breed of Bos may not have a desired STAT6 genotype, but the desired STAT6 genotype could be bred into the genepool of the favorable breed of Bos. Sorting may also be of a “virtual” nature, such that an animal's genotype is recorded either in a notebook or computer database. In this case, animals could then be selected based on their known genotype without the need for physical separation. This would allow one to select for animals of desired phenotype where physical separation is not required. 3. Distinguishing Bos taurus from Bos indicus by Determining STAT6 SNPs In a related aspect, the invention provides a method for distinguishing bovines, in particular Bos taurus from Bos indicus , based on STAT6 gene polymorphisms that are fixed in each species. The method comprises the steps of first isolating a genomic DNA sample from the bovine, and then detecting, e.g., amplifying a region of the STAT6 gene using an oligonucleotide pair to form nucleic acid amplification products of STAT6 gene polymorphism sequences. A biological sample comprising genomic DNA is taken from the bovine to be tested, as described above. The methods used to detect the STAT6 polymorphism can be any means of SNP detection known in the art, as discussed above, including without limitation, amplification, sequencing and hybridization techniques. Amplification can be by any of a number of methods known to those skilled in the art, as discussed above. Upon determining the species of the bovine based on genotypic analysis, the bovine is selected or rejected, either physically or virtually, as described above. a. STAT6 SNPs Useful to Distinguish Bos taurus from Bos indicus STAT6 SNP ID 10922 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 10922 is positioned at nucleotide 10922 of the sequence depicted in FIG. 1 , or at position 122 of SEQ ID NO:1. SNP ID 10922 is also positioned at nucleotide 122 within the 5′-UTR of the STAT6 sequence depicted in FIG. 1 . A homozygous “AA” genotype at STAT6 SNP ID 10922 indicates that the bovine is Bos taurus . A homozygous “GG” genotype at STAT6 SNP ID 10922 indicates that the bovine is Bos indicus . See, Table 3. STAT6 SNP ID 14257 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 14257 is positioned at nucleotide 14257 of the sequence depicted in FIG. 1 , or at position 3457 of SEQ ID NO:1. SNP ID 14257 is also positioned at nucleotide 24 of intron 1 of the STAT6 sequence depicted in FIG. 1 . A homozygous “CC” genotype at STAT6 SNP ID 14257 indicates that the bovine is Bos taurus . A homozygous “AA” genotype at STAT6 SNP ID 14257 indicates that the bovine is Bos indicus . See, Table 3. STAT6 SNP ID 24000 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 24000 is positioned at nucleotide 24353 of the sequence depicted in FIG. 1 , or at position 13553 of SEQ ID NO:1. SNP ID 24000 is also positioned at nucleotide 164 of intron 16 of the STAT6 sequence depicted in FIG. 1 . A homozygous “TT” genotype at STAT6 SNP ID 24000 indicates that the bovine is Bos taurus . A homozygous “CC” genotype at STAT6 SNP ID 24000 indicates that the bovine is Bos indicus . See, Table 3. STAT6 SNP ID 25999 is identified in FIG. 1 . As shown in FIG. 1 , SNP ID 25999 is positioned at nucleotide 26352 of the sequence depicted in FIG. 1 , or at position 15552 of SEQ ID NO:1. SNP ID 25999 is also positioned at nucleotide 176 of intron 20 of the STAT6 sequence depicted in FIG. 1 . A homozygous “TT” genotype at STAT6 SNP ID 25999 indicates that the bovine is Bos taurus . A homozygous “CC” genotype at STAT6 SNP ID 25999 indicates that the bovine is Bos indicus . See, Table 3. In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 10922, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-TGTGATGGGTTGAACTCTGC-3′ (SEQ ID NO:24) and 5′-CTGCCTCTCAAAAATTTATATATTA-3′ (SEQ ID NO:25); and a reverse primer comprising a nucleic acid sequence selected from 5′-GGGTACCTCCTATGAATATG-3′ (SEQ ID NO:26) and 5′-GGGATATGTGATTTCAACATA-3′ (SEQ ID NO:27). In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 14257, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-GGGCCTCTGACTACCAATGT-3′ (SEQ ID NO:9); 5′-TTTTTCCACACACCCCATCC-3′ (SEQ ID NO:28); and 5′-GGGACGTGTTAAGGC-3′ (SEQ ID NO:29); and a reverse primer comprising a nucleic acid sequence selected from 5′-CCACACCCTTGAAGAGGAAC-3′ (SEQ ID NO:10); 5′-ACTTCCCCCCAACCCAGAG-3′ (SEQ ID NO:30) and 5′-TTGCCCTCCTTCCCC-3′ (SEQ ID NO:31). In some embodiments, the polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 14257, and the oligonucleotide pair comprises forward primer 5′-GGGCCTCTGACTACCAATGT-3′ (SEQ ID NO:9) and reverse primer 5′-CCACACCCTTGAAGAGGAAC-3′ (SEQ ID NO:10). In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 24000, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-TCATTTCCCTGCTTCTGGAC-3′ (SEQ ID NO:32) and 5′-CCATCATCCATGCTCACCTTTTC-3′ (SEQ ID NO:33); and a reverse primer comprising a nucleic acid sequence selected from 5′-ATGGAATGCTTCCGGGTTAG-3′ (SEQ ID NO:34) and 5′-AGGGAGGAAGGGAGCT-3′ (SEQ ID NO:35). In one embodiment, the detected polymorphism or allele or position of the bovine STAT6 gene is at SNP ID 25999, and the oligonucleotide pair comprises a forward primer comprising a nucleic acid sequence selected from 5′-CCTCAGGATCATGCTGTGTC-3′ (SEQ ID NO:36) and 5′-CCCTTGCTCTGCTCAGA-3′ (SEQ ID NO:37); and a reverse primer comprising a nucleic acid sequence selected from 5′-TGGTTCAGGCAGCTGTCTTC-3′ (SEQ ID NO:38) and 5′-TTCTGCCATGGTCAC-3′ (SEQ ID NO:39). In some embodiments, the amplicon produced can be further subjected to restriction endonuclease digestion. 4. Kits for Genotypic Analysis of STAT6 Polymorphisms The invention further provides diagnostic kits useful for determining the STAT6 genotypes of livestock animals, e.g., bovines. In general, each of the kits comprises one or more oligonucleotide primer pairs as described herein suitable to amplify the portions of the gene comprising the SNPs of the present invention, i.e., SNP IDs 10922, 14257, 14636, 16084, 19597, 24000 and 25999. The kits comprise forward and reverse primers suitable for amplification of a genomic DNA sample taken from an animal. As described above, the biological sample can be from any tissue or fluid in which genomic DNA is present. Conveniently, the sample may be taken from blood, skin or a hair bulb. EXAMPLES The following examples are offered to illustrate, but not to limit the claimed invention. Example 1 Cattle Breed DNA Resource for SNP Discovery The cattle breed DNA resource consists of approximately 6 animals of each of 12 cattle breeds (5 Black Angus, 6 Red Angus, 3 Horned Hereford, 3 Polled Hereford, 4 Charolais, 5 Simmental, 4 Limousine, Chianina, 6 Brahman, Santa Gertrudis, 3 Wagyu). The animals of each breed were selected to be unrelated at least 3 generations back. An effort was made to have the presence of diverse lines or types within each breed. At least 5 straws of semen were obtained from each animal. The semen came from 3 sources: purchased by Merial from semen AI companies, from Charles Farber (University of California at Davis) and from Milton Thomas (New Mexico State). Tables 1 and 2 show the details of the individual samples, source and number of semen straws. High quality DNA was extracted from one semen straw from each animal and four straws kept frozen for future use. DNA was extracted using PureGene DNA extraction kit, quantified on a UV spectrophotometer and tested for integrity on an agarose gel. The DNA panel was used as a SNP discovery resource by resequencing of the STAT6 gene as described below. TABLE 1 DNA resource samples No. Source Breed Short Name Straws 1 Select Sires Black Angus Predestined 2 2 ABS Global Black Angus TRIPLE THREAT 4 3 ABS Global Black Angus EASY FORTUNE 3 4 ABS Global Black Angus CENTER CUT 4 5 Charles Farber Black Angus P S Franco 064 157 1 6 Milton Thomas Black Angus NMSU 302 DNA 7 Select Sires Red Angus Field Day 2 8 Select Sires Red Angus Vigor 2 9 Select Sires Red Angus Ho Ho 2 10 Select Sires Red Angus Heavenly 2 11 Select Sires Red Angus Duke 2 12 Select Sires Red Angus Rambler 2 13 Select Sires Hereford Polled Formula 2 14 ABS Global Hereford Polled JEDI 4 15 ABS Global Hereford Polled MASTER DUTY 4 16 ABS Global Horned HR ROBIN HOOD 4 Hereford 17 ABS Global Horned Star Donald 4 Hereford 18 Charles Farber Horned CL 1 Domino 0144K 1 Hereford 1ET 19 Charles Farber Horned HH Advance 249B 2 Hereford 20 Select Sires Charolais Choice Plus 2 Creme 21 Select Sires Charolais Sir Prime Time 2 Creme 22 ABS Global Charolais SILVER EDGE 4 Polled 23 ABS Global Charolais SENTINAL RULER 4 scurred 24 Select Sires Simmental Red Autobahn 2 25 Bovine Elite Simmental Red ER Americana 537B 4 26 Bovine Elite Simmental Red NLC Good A Nuff 33G 4 27 ABS Global Simmental FUTURE 4 Traditional MODERATOR 28 Universalsemensales Simmental BEL DUTCH 89X 4 Traditional 29 Bovine Elite Simmental Bar 5 Bernheim 405H 4 Traditional 30 ABS Global Gelbvieh Red TOP BRASS 4 31 ABS Global Gelbvieh Red TABASCO 4 32 ABS Global Gelbvieh Red SIR ARNOLD 4 33 ABS Global Gelbvieh Red MODERATOR 4 34 Select Sires Limousin Black Equity 2 35 ABS Global Limousin Red POLLED 4 MANHATTAN 36 ABS Global Limousin Red JUSTICE 4 37 Bovine Elite Limousin Red EXLR Latigo 029M 4 38 Universalsemensales Wagyu “A” BR Fukutsuru 0620 4 39 Universalsemensales Wagyu “B” BR Takazakura 0604 4 40 Universalsemensales Wagyu “C” BR Hirashigotayasu 4 9645 41 Select Sires Brangus Carrarra 2 42 Milton Thomas Brangus NMSU 830 DNA 43 Milton Thomas Brangus NMSU 628 DNA 44 Milton Thomas Brangus CCR INTEGRITY DNA F386F2 45 Milton Thomas Brangus John Wayne 44L DNA 46 Milton Thomas Brangus NIMITZ OF BRINKS DNA 75L12 47 Milton Thomas Brangus Mr 304 (Lucky) 118 DNA 48 Milton Thomas Brahman 6X Sunland 874 DNA 49 Milton Thomas Brahman SRW MR. FLYING W DNA 831 50 Milton Thomas Brahman JDH MR. SALLUTO DNA MANSO 300/2 51 Select Sires Brahman 852/5 2 52 Select Sires Brahman Rojo Bueno 2 53 Bovine Elite Brahman BB Mr Sting-Ray 10/0 4 54 Bovine Elite Shorthorn ALM Tequila 2 55 Bovine Elite Shorthorn SBR Storm Chaser 4 56 Bovine Elite Shorthorn BG Spanky TPII 4 57 Bovine Elite Romagnola Danure Hublo 3 58 Universalsemensales Salers TV Big Red 4 59 Bovine Elite Santa Gertrudis Gambler II 817 4 60 Bovine Elite Senepol HBC 7115 48K 4 61 Select Sires Beefmaster P.D.Q. 2 TABLE 2 DNA Repository (Samples Sequenced for STAT6) ID Source Breed Short Name BA1 Select Sires Black Angus Predestined BA2 ABS Global Black Angus TRIPLE THREAT BA3 ABS Global Black Angus EASY FORTUNE BA4 ABS Global Black Angus CENTER CUT BA5 Charles Farber Black Angus P S Franco 064 157 RA1 Select Sires Red Angus Field Day RA2 Select Sires Red Angus Vigor RA3 Select Sires Red Angus Ho Ho RA4 Select Sires Red Angus Heavenly RA5 Select Sires Red Angus Duke RA6 Select Sires Red Angus Rambler HP1 Select Sires Hereford Polled Formula HP2 ABS Global Hereford Polled JEDI HP3 ABS Global Hereford Polled MASTER DUTY HH1 ABS Global Horned Hereford HR ROBIN HOOD HH3 Charles Farber Horned Hereford CL 1 Domino 0144K 1ET HH4 Charles Farber Horned Hereford HH Advance 249B SR1 Select Sires Simmental Red Autobahn SR2 Bovine Elite Simmental Red ER Americana 537B SR3 Bovine Elite Simmental Red NLC Good A Nuff 33G ST1 ABS Global Simmental FUTURE Traditional MODERATOR ST2 Universalsemensales Simmental BEL DUTCH 89X Traditional ST3 Bovine Elite Simmental Bar 5 Bernheim 405H Traditional CC1 Select Sires Charolais Creme Choice Plus CC2 Select Sires Charolais Creme Sir Prime Time CP1 ABS Global Charolais Polled SILVER EDGE CS1 ABS Global Charolais scurred SENTINAL RULER GR1 ABS Global Gelbvieh Red TOP BRASS GR2 ABS Global Gelbvieh Red TABASCO GR3 ABS Global Gelbvieh Red SIR ARNOLD GR4 ABS Global Gelbvieh Red MODERATOR LB1 Select Sires Limousin Black Equity LR1 ABS Global Limousin Red POLLED MANHATTAN LR2 ABS Global Limousin Red JUSTICE LR3 Bovine Elite Limousin Red EXLR Latigo 029M WG1 Universalsemensales Wagyu “A” BR Fukutsuru 0620 WG2 Universalsemensales Wagyu “B” BR Takazakura 0604 WG3 Universalsemensales Wagyu “C” BR Hirashigotayasu 9645 BR1 Select Sires Brangus Carrarra BR2 Milton Thomas Brangus NMSU 830 BR3 Milton Thomas Brangus CCR INTEGRITY F386F2 BR4 Milton Thomas Brangus John Wayne 44L BH1 Select Sires Brahman 852/5 BH2 Select Sires Brahman Rojo Bueno BH3 Bovine Elite Brahman BB Mr Sting-Ray 10/0 BH4 Milton Thomas Brahman 6X Sunland 874 BH5 Milton Thomas Brahman SRW MR. FLYING W 831 BH6 Milton Thomas Brahman JDH MR. SALLUTO MANSO 300/2 Example 2 SNP Discovery Platform Using Resequencing Strategy A strategy for SNP discovery was developed for this project. SNPs were identified by resequencing candidate genes in panels of 48 animals (9 breeds) from the discovery panel. See, Table 2. A genomic reference sequence was assembled from GenBank sequences (genomic, mRNA and ESTs) and from Ensembl bovine genome sequences. The sequence was annotated to identify exons, introns, 2000 bp of the promoter and 1000 bp of the 3′ untranslated region. Repetitive and low-complexity sequences were masked with RepeatMasker to prevent sequencing repetitive regions of the genes. The sequencing project was outsourced to SeqWright (Houston, Tex.). SeqWright provided a full service of automated sequencing with a brief annotation and SNP discovery. Sequence traces were downloaded from SeqWright and resembled at UCDavis using software CodonCode Aligner to notate and discover SNPs. The genotype of the sequenced animals for each gene were analyzed using haploview software (on the worldwide web at broad.mit.edu/mpg/haploview/) to define haplotypes and to choose a minimal information subset of Tag SNPs for genotyping. In addition, computational algorithms were used, for example, SIFT and PolyPhen, to predict the impact of nucleotide or amino-acid substitutions on protein structure and function. These algorithms were useful to flag unique mutations of interest. Example 3 Identify SNPs in STAT6 Using a bioinformatics-based method to identify sequence homologies between bovine microsatellites (Farber and Medrano 2003, Animal Genetics 34, 11-18), and gene sequencing it was demonstrated that microsatellite ETH10 is located within the first exon of the bovine STAT6 gene. ETH10 has been strongly associated in earlier work with marbling in Wagyu cattle (Barendse, Australia), with a suggestion of RDH5 as being the causative gene. It was proposed that the association between ETH10 and marbling is either due to the repeat itself or polymorphisms with the STAT6 gene, which alter its function. Earlier, 3 SNPs between different breeds of dairy cattle were identified. 39 SNPs across the complete gene have been identified overall, in the 48 animals breed panel. FIG. 1 shows an annotated sequence of the bovine STAT6 gene and the position of Tag SNPs statistically correlated with economically important traits in beef cattle. Table 3 shows flanking sequences of individual SNPs. After defining haplotypes and regions of linkage disequilibrium in the STAT6 genes of the selected animals, identified 15 Tag SNPs were identified. Tag SNPs are a minimal information subset of SNPs that capture all the variation of a gene in defined populations. Three of the SNPs, 14636, 16084 and 19597, are statistically correlated with economically important carcass and feedlot traits in beef cattle. See, Table 4. Four of the SNPs, 10922, 14257, 24000 and 25999, are fixed in Bos taurus and in Bos indicus and therefore find use in genotypically distinguishing these two species. The association analysis was performed using the Golden Helix Regression Analysis Module from Helixtree software. The Golden Helix Regression Module was used to test allelic associations with phenotypic variables. The Regression Module supports both linear and logistic regression. A stepwise regression was used to find confounding phenotypic variables, regressors were fixed, and then a search for significantly associated SNPs was performed. This regression approach is particularly powerful for overcoming the difficult challenges of population stratification. Permutation testing increased the flexibility of the analysis. Table 4 shows the significant results for the association analysis. TABLE 3 Sequences Flanking SNPs in STAT6 Gene PolyID Species Context 14636 Bos taurus GGGTGGGAGTGGGGGAAAGTCTGGCCC SEQ ID CTCGCTGTCGGAGGATGGAGTAGGGGA NO: 2 GATTTGAAGGCAGGGCCATGCCAGGAA GCTGGTCACTCTTCCTAATCTAGGGGA TATGGAGGAAAGGGGAGCTGCCTCTGA CTTAGGGATCACCTC [C/G] GTCCCCG TAGGGTAGAGATAGAGGTCAAAGGTCT GAGCACCCTGAGAAACAGGAGAGAAAG AGGGAAGAGAGGAATGGAGTCCTCCCT TGAGTTTGAAACACAAACCAAAAGGTG CCCCACCCCAAGGTGGGTGTAGAGAAA GGTCTAT 16084 Bos taurus ATTGGCAGCATGGAGTCTTAGCCACTG SEQ ID GATCACCAGAGAAGTTCCGAGGGGAGG NO: 3 TTTCCTGCCAACAGAATCAGAGCTACA ACCCACATTCTCTGCCTTCTCTCAGAG AGCTTTCCCTACTGCCCCATTGCCCCT GTCTCTTACCCTCT [C/A] CCCTCCCC CAACTGGCTGCAGCTCAGCTCTTCCCA CTCCATTACCCCCATGCCTACTGTTGA AGAAAATACCTTGTTTCAGGCTTTGGC CAAAGAGGTTCCTGGTTTGATATAGTC TGRCTGAGAGTTGTGGTGCTGATGGTC TCTGAAA 19597 Bos taurus TGTGAGAGCCTGGTGGACATTTATTCC SEQ ID CAGCTGCAGCAGGAGGTGGGGGCAGCT NO: 4 GGTGGGGAGCTTGATCCCAAGACCCGG GCAGCGCTGATTAGCCGACTGGATGAA GTCCTGCGCACACTCGTCACCAGGTAT GAGCCCCCCTGCCTG [G/A] TGGAGAG CAGACCCCAAGGAAACAGGAGGGTCAG AGTTGTGGTGGGGGGAGGGGCAGTGGC GCCCAGAGGGACCCAGCTGTTCACTTC CCTGTGTCTTCCTTACTCCTCCCAGCT CTTTCCTGGTGGAAAAGCAGCCCCCCC AGGTTCTG 10922 Bos taurus / AAGTGAAACAAATTTCATTAGACACTA SEQ ID indicus CTTATCCTTACTTTGTGTCATGCATTC NO: 5 TGGTATTTTTTATTGTATTCTACTTTG TTTTTAAATACTGGTGGTCAAGGCTCA CTGTGATGGGTTGAACTCTGCCTCTCA AAAATTTATATATTA [A/G] TATGTTG AAATCACATATCCCTCAAAAATTCATA TTCATAGGAGGTACCCTCAGTCCCTCA GAATGTGACCTTATTCAGATATAGGGT CTTTACAGAGGAAATCTTTAGGGTGGG CCCTAATCCAATATGACTGATGTCTTT AGAAAAAG 14257 Bos taurus / GCTGGTGGCTGGTGTTACTGAGTTTCG SEQ ID indicus GCAGTTTCGAAATATCAGAGGAATCTG NO: 6 GAGTGGGTACAGGCCCAGCACTTGCCC CGCTCCTCCCCAACATGGGTCACTTTT TCCACACACCCCATCCCCCGCAATCCA GGGACGTGTTAAGGC [C/A] GGGGAAG GAGGGCAAGGAGGTGCCCCTCTGCCCT CTGGGTTGGGGGGAAGTGGCCGCCCCT CCCTATAGAAAACTGATGGCAGGGGGC AGTGGATCCTCCACAGACCCCTATCCG GGCCCCCCACAAAGGTTCCTCTTCAAG GGTGTGGC 24000 Bos taurus / CGGGGCTGGCAGCTCTGACTCCTTCTG SEQ ID indicus TGGTCCGCCTCCTCCCTGCTCCTGGTT NO: 7 GCCCCCACCCCACCTGCTGTGTGTCAT CCCTGACTTCTTCCTCCATTGTCATTT CCCTGCTTCTGGACCCTGCCCATCATC CATGCTCACCTTTTC [T/C] AGCTCCC TTCCTCCCTAACCCGGAAGCATTCCAT GGCTCTCCTTTCCTCCCCACAATAGCT GAGCAGATGGGTAAGGATGGCAGGGGT TATGTCCCAGCTACAATCAAGATGACT GTGGAAAGGTGAGTGTGCTGGTGTGGA TGGAGGGC 25999 Bos taurus / TGAGCTCAAGCTCCTCATTCATYCCCR SEQ ID indicus GCCTCAACCCCACCCTGACCCCCCCCA NO: 8 CCACCTCATTTACTTCTCTGGGGCTGG CAGGGGCCTGCTGCCGTGCCCACCTCA GGATCATGCTGTGTCCAGCCCTGAGCC CTTGCTCTGCTCAGA [T/C] GTGACCA TGGCAGAAGACAGCTGCCTGAACCAGC CGGTGGGAGGGTTCCCTCAAGGCACCT GGTGAGTGTCAGCCTGGGGGTGGAGGC TGGGTGGGGGGTTGCGGTGTGGGTACC ATGCCTATCCCACTGCTTCTCCACTCC TCTCTGCA TABLE 4 EFFECT OF STAT6 GENOTYPES ON PERFORMANCE AND CARCASS TRAITS IN BEEF CATTLE STAT6 SNP Allele Subs. 16084 AA AC CC P-value b Additive Effect Dominace Effect Effect a Back Fat 0.59 ± 0.07 0.51 ± 0.01 0.47 ± 0.005 0.00030 0.12 ± 0.06 −0.02 ± 0.04 0.08 P = 0.0004 P = 0.001 P = 0.0002 Calculated 3.1 ± 0.2 2.82 ± 0.05 2.66 ± 0.02 0.0031 0.44 ± 0.1 −0.06 ± 0.02 0.32 yield grade P = 0.011 P = 0.013 P = 0.0009 Cutability 49.5 ± 0.6 50.1 ± 0.1 50.46 ± 0.05 0.0029 −0.96 ± 0.3 0.12 ± 0.1 −0.76 P = 0.011 P = 0.013 P = 0.0087 STAT6 SNP Allele Subs. 19597 AA AG GG P-value b Additive Effect Dominace Effect Effect a Hot carcass 762 ± 4 754 ± 3 744 ± 4 0.0019 18 ± 4 1 ± 4 18.26 weight P = 0.002 P = 0.008 P = 0.002 Dry matter 2945 ± 29 2909 ± 19 2825 ± 23 0.0018 120 ± 24 24 ± 22 120.45 intake P = 0.00013 P = 0.0016 P = 0.001 Days on feed 138 ± 1 141.5 ± 1 144 ± 1 0.00088 −6 ± 1 0.5 ± 1 6.12 P = 0.0007 P = 0.003 P = 0.0007 STAT6 SNP Allele Subs. 14636 CC CG GG P-value b Additive Effect Dominace Effect Effect a BFAT RATE 0.0131 ± 0.0004 0.0126 ± 0.0002 0.0117 ± 0.0001 2.34E−07 0.0014 ± 0.0002 0.0002 ± 0.0001 0.0015 P = 0.0032 P = 0.0076 P = 1.6E−6 Days on feed 136 ± 1 139.8 ± 1 144 ± 1 1.51E−05 −8 ± 1 −0.2 ± 1 −8.2 P = 2.6E−5 P = 0.0001 P = 2.6E−5 Average daily 3.83 ± 0.02 3.70 ± 0.03 3.61 ± 0.02 4.52E−05 0.22 ± 0.02 −0.02 ± 0.02 0.19 gain P = 0.002 P = 0.01 P = 0.0001 a Allele substitution effect estimated by regression of phenotype on genotype dummy variables. The effect represents the regression coefficient (equal to the absolute effect) of genotype. b P value from overall F-test. Example 4 Detection of SNP ID 14257 Using PCR-RFLP Protocol This example shows a PCR/RFLP genotyping assay for STAT6 SNP ID 14257. Detecting polymorphisms at SNP ID 14257 differentiates between Bos taurus and Bos indicus species. The nucleotide at SNP ID 14257 of the bovine STAT6 gene is PCR amplified from bovine genomic DNA template using forward primer 5′-GGGCCTCTGACTACCAATGT-3′ (SEQ ID NO:9) and reverse primer 5′-CCACACCCTTGAAGAGGAAC-3′ (SEQ ID NO:10). The PCR amplification conditions are as follows: dH 2 O 17.3 μl 10x PCR buffer 2.5 μl 50 mM MgCl 2 1.5 μl 10 mM dNTPs 0.5 μl 10 pmol/μl Primers 1 μl each Taq polymerase 5U 0.2 μl DNA 50 ng 1 μl Total Volume 25 μl The PCR reaction is run for 35 cycles: 30 sec. at 94° C.; 30 sec. at 60° C.; and 30 sec. at 72° C. The amplified PCR amplicons (397 bp when uncut) are then subject to restriction endonuclease digestion with MspI. If the bovine is a Bos taurus , then the restriction endonuclease digestion produces fragments of 36 bp, 114 bp and 247 bp. If the bovine is a Bos indicus , then the restriction endonuclease digestion produces fragments of 361 bp and 36 bp. A representative result is shown in FIG. 3 . It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes.	The present invention provides for selection of livestock animals, including bovines, whose genotypes based in the STAT6 gene are correlated with phenotypes reflecting desirable carcass and feedlot traits. These phenotypes include back fat (BFAT), calculated yield grade (CALCYG), cutability (CUT), hot carcass weight (HCW), dry matter intake (DMI), days on feed (DOF), back fat rate (BFAT RATE) and average daily gain (ADG), based on the knowledge of the STAT6 genotypes. The predictive value is based in part on the discovery that certain single nucleotide polymorphisms (SNPs) within the STAT6 gene are linked to phenotypes of economically these important carcass and feedlot traits. Also provided are SNPs within the STAT6 gene useful in reliably distinguishing between a Bos taurus and a Bos indicus bovine. The invention provides methods and compositions for determining STAT6 genotypes and for screening livestock animals to predict which animals will have desirable carcass traits and feedlot traits, allowing producers to selectively breed and manage animals based on desired characteristics, thereby maximizing productivity and profitability in commercial meat production operations.	2
TECHNICAL FIELD The present invention relates generally to enclosures for encapsulating electrical transformers and, more particularly, to expandable enclosures for encapsulating various sizes of current transformers. BACKGROUND OF THE INVENTION Transformers are used extensively in electrical and electronic applications. Transformers are useful to step voltages up or down, to couple signal energy from one stage to another, and for impedance matching. Transformers are also useful for sensing current and powering electronic trip units for circuit interrupters such as circuit breakers and other electrical distribution devices. Other applications for transformers include magnetic circuits with solenoids and motor stators. Generally, a transformer consists of two or more windings (primary and secondary, etc . . . ) interlinked by a mutual magnetic field. As such, the transformer is used to transfer electric energy from one circuit to another circuit using magnetic induction. Current transformers are used to monitor current flow in a circuit, such as to detect excessive power consumption and provide a warning signal or disconnect the power supply. The transformer must be protected from potential hazzards in its immediate environment with some type of sealing enclosure. Current transformers, as well as transformers in general, are shape and size specific to the end user's electrical needs and mounting specifications. Accordingly, this presents a unique challenge to designing and manufacturing a transformer and an enclosure therefor which delivers the required electrical performance with the required mounting specifications, all in the confines of a secure enclosure. Various types of sealing enclosures are currently utilized to protect the transformer from the environment. One means for protecting transformers includes entirely sealing the transformer assembly with an epoxy resin. This is accomplished by pouring the epoxy resin into a molded container which houses the transformer to completely surround and encase the transformer coil with the epoxy resin. Epoxy is utilized because it prevents impact or vibrational shock from affecting the function of the transformer. However, several drawbacks are associated with epoxy encapsulated transformers: (1) using epoxy to encapsulate the transformer is a time consuming process, and (2) the use of epoxy prevents subsequent repairs to the transformer since the transformer is permanently encapsulated by the epoxy. Another means for encapsulating transformers includes fastening two separate enclosures together. Typically, the enclosure comprises of two housinghalves which are connected by screws. As with an epoxy enclosure, this type of housing also has several drawbacks. One specific drawback is the increased capital investments in tooling required for each different enclosure. Typically, as the electrical specifications change for a specific transformer, the size of the transformer also changes. Accordingly, the enclosure for the transformer must also be modified. It is very common, however, for the change in transformer size to effect the depth of the transformer, and not the width or height. Thus, modifying the depth of a transformer requires modifying the mounting depth of the enclosure which results in the tooling of a new molded enclosure. The cost of new tooling is very expensive. Accordingly, there is a need for an effective and efficient means for providing a protective enclosure for encapsulating various sizes of transformers, and specifically current transformers. Such an enclosure must not only provide all of the necessary safety features, but should also allow for quick assembly/disassembly of the enclosure and accessibility for repairs of the transformer. Additionally, the enclosure should eliminate the need for new tooling and additional capital expenditures for manufacturing a variety of sizes of transformer enclosures. SUMMARY OF THE INVENTION The transformer enclosure or housing of the present invention allows for the incremental expansion in mounting depth of the enclosure for a transformer without having to invest additional money in new tooling. The transformer enclosure of the present invention also allows for subsequent disassembly of the enclosure for repair of the transformer therein, as required. According to one aspect of the present invention, the housing includes a first housing member, a second housing member, and an exterior insert member between the first and second housing members. The insert member has a first end and a second end. A portion of the first end of the insert member is adapted to engage the first housing member, and a portion of the second end of the insert member is adapted to engage the second housing member. The insert member comprises an exterior shell member which increases the length of the housing, and thus the interior volume of the housing, to allow the housing to accept larger transformers without manufacturing larger housing halves. According to another aspect of the present invention, an aperture is provided through the center of the housing. An interior insert member is provided to bridge the gap adjacent the aperture, i.e., between the first and second housing members, similar to the exterior insert member. Like the exterior insert member, the interior insert member has a first end and a second end. A portion of the first end of the interior insert member is adapted to engage the first housing member adjacent the aperture therethrough, and a portion of the second end of the insert member is adapted to engage the second housing member adjacent the aperture therethrough. Like the exterior insert member, the interior insert member generally comprises an exterior shell member adjacent the aperture which increases the length of the aperture housing, and thus the interior volume of the housing, to allow the housing to accept larger transformers. Generally, the interior and exterior insert members have a height dimension that is substantially equal. According to another aspect of the present invention, the first and second housing members, along with the interior and exterior insert members, have mating members which allow adjacent housing and insert members to engage and mate with one another in a stackable manner. In one of the preferred embodiments of the present invention, the mating members comprise an integral female recess, and an integral male lip or protrusion. Specifically, in a housing having a single interior and exterior insert: (1) the first housing member has an exterior male lip that depends from substantially the perimeter of an outer wall of the first housing member, and an interior male lip that depends from substantially the perimeter of the wall adjacent the aperture thereof; (2) the second housing member has an exterior female recess that depends from substantially the perimeter of an outer wall of the second housing member, and an interior female recess that depends from substantially the perimeter of the wall adjacent the aperture thereof; (3) the exterior insert has a female recess that depends from substantially the perimeter of the first end of the exterior insert, and a male lip that depends from substantially the perimeter of the second end of the exterior insert; and, (4) the interior insert has a female recess that depends from substantially the perimeter of the first end of the interior insert, and a male lip that depends from substantially the perimeter of the second end of the interior insert. As such, the respective male lips of the first housing member engage and mate with the respective female recess of the first end of each of the interior and exterior inserts, and the respective female recesses of the second housing member engage and mate with the respective male lip of the second end of each of the interior and exterior inserts, respectively. According to another aspect of the present invention, a plurality of interior and exterior inserts are provided to sequentially expand the depth of the transformer housing. Each insert member has respective mating members substantially as described above. According to another aspect of the present invention, the first and second housing members, along with the plurality of inserts therebetween, are fixed together to encapsulate the transformer therein. Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings. Brief Description of the Drawings To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which: FIG. 1 is a perspective view showing an expandable enclosure for a transformer housing according to the present invention; FIG. 2 is an exploded perspective view of the expandable transformer enclosure of FIG. 1; FIG. 3 is a cross-sectional view taken along line 3 - 3 of FIG. 1; FIG. 4 is a cross-sectional view taken along line 4 - 4 of FIG. 2; and, FIG. 5 is a cross-sectional view taken along line 5 - 5 of FIG. 2 ; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. Referring now in detail to the Figures, and initially to FIGS. 1 and 2, there is shown an expandable housing 10 for a transformer (not shown). The expandable housing 10 is configured to surround and encase the transformer to protect the transformer from damage from the outside environment. The expandable housing 10 includes a first housing member 12 , a second housing member 14 , two exterior insert members 16 , 16 a and two interior insert members 18 , 18 a . The interior insert members 16 , 16 a and exterior insert members 18 , 18 a are located between the first and second housing members 12 , 14 . Each of the members 12 , 14 , 16 , 16 a , 18 , 18 a are adapted to interconnect and engage or mate with adjacent members via interconnecting means in a stackable manner. Accordingly, if additional insert members ( 16 . . . 16 n ),( 18 . . . 18 n ) are required to expand the transformer housing 10 , such insert members are merely located between the first and second housing members 12 , 14 in an interconnected, engaging, and stacked manner, resulting in more separation between enclosure halves. The stacking of the inserts is only limited by the requirements on the depth of the mounting for the transformers. The embodiment illustrated in the Figures has an aperture 20 extending from the first housing member 12 to the second housing member 14 which allows for current transformers. Specifically, the aperture 20 and the inner insert members 18 , 18 a allow for a bus bar (not shown) or the primary and secondary windings (not shown) to pass through the aperture 20 in the housing members. The aperture 20 in the housing 10 provides insulation between the customer's current source and the secondary windings of the current transformer. As shown in FIGS. 2 and 3, the first housing member 12 has a closed end 22 defined by a back wall 24 with an aperture 20 therethrough, and an open end 26 opposing the closed end 22 . An outer wall 28 depends from the back wall 24 , and a first exterior mating member 30 depends from a perimeter of the outer wall 28 adjacent the open end 26 thereof Additionally, an interior wall 32 depends from the back wall 24 and a first interior or inner mating member 34 depends from a perimeter of the interior wall 32 adjacent the aperture 20 of the first housing member 12 . The combination of the back wall 24 , outer wall 28 , and interior wall 32 defines a hollow cavity 35 in the housing member 12 . Similarly, the second housing member 14 has a closed end 42 defined by a back wall 44 with an aperture 20 therethrough, and an open end 46 opposing the closed end 42 . An outer wall 48 depends from the back wall 44 , and a second exterior mating member 50 depends from a perimeter of the outer wall 48 adjacent the open end 46 thereof. Additionally, an interior wall 52 depends from the back wall 44 and a second interior or inner mating member 54 depends from a perimeter of the interior wall 52 adjacent the aperture 20 of the second housing member 14 . The combination of the back wall 44 , outer wall 48 , and interior wall 52 defines a hollow cavity 55 in the housing member 14 . As illustrated in FIGS. 2-4, the first exterior insert member 16 and the second exterior insert member 16 a are located between the first housing member 12 and the second housing member 14 . In this embodiment, with two exterior insert members 16 , 16 a , the first exterior insert member 16 is specifically located between and adjacent the first housing member 12 and the second exterior insert member 16 a , and the second exterior insert member 16 a is specifically located between and adjacent the first exterior insert member 16 and the second housing member 14 . The first and second exterior insert members 16 , 16 a each have a first end 56 and a second end 58 opposing the first end 56 . As shown in FIG. 4, first mating member 60 is adjacent the first end 56 of the exterior insert members 16 , 16 a , and a second mating member 62 is adjacent the second end 58 of the exterior insert members 16 , 16 a . As illustrated in FIGS. 2 and 3, the first mating member 60 of the first exterior insert member 16 is adapted to and is capable of engaging and mating with the first exterior mating member 30 of the first housing member 12 . The second mating member 62 of the first exterior insert member 16 is adapted to and is capable of engaging and mating with the first mating member 60 of the second exterior insert member 16 a . And, the second mating member 62 of the second exterior insert member 16 a is adapted to and is capable of engaging and mating with the second exterior mating member 50 of the second housing member 14 . Additionally, a first interior insert member 18 and a second interior insert member 18 a are located between the first housing member 12 and the second housing member 14 . The interior insert members 18 , 18 a are generally located within the confines of exterior insert members 16 , 16 a . In this embodiment with two interior insert members 18 , 18 a , best illustrated in FIGS. 2 and 3, the first interior insert member 18 is specifically located between the first housing member 12 and the second interior insert member 18 a , and the second interior insert member 18 a is specifically located between the first interior insert member 18 and the second housing member 14 . As shown in FIG. 5, each of the first and second interior insert members 18 , 18 a , have a first mating member 64 adjacent a first end 66 thereof, and a second mating member 68 adjacent a second end 70 thereof. The first end 66 of each interior insert member 18 , 18 a opposes the second end 70 of each interior insert member 18 , 18 a . As illustrated in FIG. 2, the first mating member 64 of the first interior insert member 18 is adapted to engage and mate with the first interior mating member 34 of the first housing member 12 . The second mating member 68 of the first interior insert member 18 is adapted to engage and mate with the first mating member 64 of the second interior insert member 18 a . And, the second mating member 68 of the second interior insert member 18 a is adapted to engage and mate with the second interior mating member 54 of the second housing member 14 . As such, the first housing member 12 , the first and second exterior and interior mating members 16 , 16 a , 18 , 18 a , and the second housing member 14 are all connectable to form the stackable transformer housing 10 of the present invention. For purposes of mating adjacent members, in the preferred embodiments each housing member 12 , 14 and insert member 16 , 16 a , 18 , 18 a generally has a male mating means or a female mating means at one end thereof. In the preferred embodiments, as best shown in FIGS. 2-5, the first exterior mating member 30 of the first housing member 12 is a male means or a protrusion 30 extending from the perimeter of the outer wall 28 of the first housing member 12 , and the second exterior mating member 50 of the second housing member 14 is a female means or an indentation 50 adjacent the perimeter of the outer wall 48 of the second housing member 14 . Also as shown in FIGS. 2-5, the exterior insert members 16 , 16 a , and the interior insert members 18 , 18 a , have a male means or protrusion extending from one end thereof, generally the second end, and have a female means or indentation adjacent the other end thereof, generally the first end. Further, the male mating member or means in the illustrated embodiment can also be identified as an integral lip about a perimeter of the end thereof, and the female mating member or means can also be identified as an integral recess adjacent the end thereof The male means, protrusion, or lip of any member identified herein is dimensioned to engage the female means, indentation, or recess of any adjacent member identified herein. In general, the male mating member of any component is capable of mating with the female mating member of any other component to form an encapsulating exterior portion of the transformer housing 10 . While the male mating means in the preferred embodiment is identified as a protrusion or lip and the female mating means in the preferred embodiment is identified as an indentation or recess, other mating means are also viable, including threaded means, gasket means, adhesives, mechanical fasteners, etc . . . . As best shown in FIG. 3, (starting from the left most housing member 12 and continuing to the right most housing member 14 in FIG. 2) the male lip of the first exterior mating member 30 engages the female recess of the first mating member 60 of the first exterior insert member 16 ; the male lip of the first interior mating member 34 engages the female recess of the first mating member 64 of the first interior insert member 18 ; the male lip of the second mating member 62 of the first exterior insert member 16 engages the female recess of the first mating member 60 of the second exterior insert member 16 a ; the male lip of the second mating member 68 of the first interior insert member 18 engages the female recess of the first mating member 64 of the second interior insert member 18 a ; the male lip of the second mating member 62 of the second exterior insert member 16 a engages the female recess of the second exterior mating member 50 of the second housing member 14 ; and, the male lip of the second mating member 68 of the second interior insert member 18 a engages the female recess of the second interior mating member 54 of the second housing member 14 . The members are then drawn together, generally with the use of screws, and are then fixed together. Each insert member, both interior and exterior, has a height dimension (H). Generally, the height dimension (H) of the exterior and interior insert members is substantially equal. Accordingly, with current transformers, for each exterior insert member 16 added to the expandable housing 10 an interior insert member 18 will also be required. Also, the height dimension of the first and second housing members 12 , 14 may be greater or less than the height dimension of the insert members 16 , 18 . The above described housing components and mating elements thereof allow for a transformer housing 10 including: (1) a first housing member 12 and a second housing member 14 only, and no insert members; (2) one pair of mating members 16 , 18 between first and second housing members 12 , 14 ; (3) two pair of mating members 16 , 16 a , 18 , 18 a between first and second housing members 12 , 14 ; (4) three pair of mating members 16 , 16 a , 16 b , 18 , 18 a , 18 b between first and second housing members 12 , 14 ; and so on and so forth, etc . . . . Additionally, it is understood that with certain transformers, interior insert members and apertures through the back wall of the housing members are not required. In such instances, if the housing 10 is required to be expanded to contain a larger transformer, additional exterior insert members 16 are merely inserted and mated between the first and second housing members 12 , 14 . In the embodiment wherein no mating members are utilized the first exterior mating member 30 of the first housing member 12 mates with the second exterior mating member 50 of the second housing member 14 , and the first interior mating member 34 of the first housing member 12 mates with the second interior mating member 54 of the second housing member 14 . When all components of the transformer housing 10 have been mated together in the above stated manner, the enclosure 10 is sealed. Generally, screws Is 15 placed in a tapped hole of the housing complete the securement of the housing. Then, wire terminals (not shown) are connected to the housing, fixed in place, and external wire leads are connected to the final transformer enclosure assembly. Finally, the transformer housing 10 is mounted with mounting fixtures placed through the mounting holes 72 in the housing 10 . In the embodiments disclosed the first housing member 12 is shown to have male mating members 30 , 34 , and the second housing member 14 is shown to have female mating members 50 , 54 . It is possible, however, that the mating members of the first housing member 12 may possess female characteristics, and the mating members of the second housing member 14 may possess male characteristics. Additionally, both the first housing member 12 and the second housing member 14 may contain all male mating members or all female mating members as long as the insert members 16 , 18 have the appropriate corresponding mating members. While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.	An expandable transformer housing having a first housing member with a hollow cavity therein, a second housing member with a hollow cavity therein, and at least one exterior insert member therebetween in a stacked formation. The exterior insert member has a first end and a second end. A portion of the first end of the exterior insert member is adapted to engage the first housing member and a portion of the second end of the insert member is adapted to engage the second housing member. An interior insert member is also provided having a first end and a second end. A portion of the first end of the interior insert member is similarly adapted to engage the first housing member and a portion of the second end of the interior insert member is adapted to engage the second housing member. The interior insert provides insulation between the current source and the second windings of the transformer. The exterior and interior inserts are designed to expand the mounting depth of the transformer's enclosure to provide a stacked design in an interlocking manner.	7
FIELD OF THE INVENTION The present invention relates to an automatic speed shifting device which employs a torque feedback device to change the position of a shift gear so as to engage corresponding shifting member in the transmission device. The speed reduction device automatically shifts the transmission device when the load torque increases or reduces. BACKGROUND OF THE INVENTION A conventional power transmission device, especially for electric spinning tools, such as electric drills and electric screwdrivers, includes a multiple-stage power transmission device and a speed reduction device is used to provide multiple speeds or torque. Generally, the speed reduction device is composed of a planetary gear system and clutch or driving members in the speed reduction device are manually controlled such that some parts are fixed or moved in the planetary gear system and the purposes of speed reduction of output or input can be achieved. An operator has to judge the situation of the tool and then decide to operate the manual device to activate proper speed reduction device to obtain desired torque or revolutions of speed. It is difficult to make the efficiency of the driving motor optimized by the manual operation. Therefore, a feedback device for the load torque is needed so as to shift proper steps of the speed reduction device. SUMMARY OF THE INVENTION In accordance with an aspect of the present invention, there is provided an automatic speed shifting device that comprises a frame having a transmission device and a torque feedback device received therein. The frame has a plurality of triangle shaped slots defined through a wall thereof. A radial groove is defined through the wall of the frame. A plurality of protrusions extending from an inside of the frame and ridges are defined on an outer surface of the frame. The transmission device has a shifting gear that has inner teeth that are engaged with first planet gears and second planet gears. The shifting gear has an annular groove with which a plurality of pins on a clamp are engaged so as to retain the shifting gear in a first stage speed position and to engage the shifting gear with the two planet gears, or retain the shifting gear in a second stage speed position and only engage the shifting gear with the second planet gears. The torque feedback device has a pushing wheel, a C-shaped clamp and a compression spring. The pushing wheel has a lever extending from an outer surface thereof and the clamp has a plurality of pin extending through the slots of the frame and engaged with the annular groove of the shifting gear. An elongate hole is defined through the clamp and located corresponding to the radial groove of the frame and the lever of the pushing wheel. The compression spring is mounted to the frame and retained between rides and the ridges on the frame. When the pushing wheel is rotated, the lever is moved in the radial groove of the frame and drives the clamp via the elongate hole in the clamp. The clamp compresses the compression spring by a movement along an inclined surface of the radial groove of the frame so as to generate resistant force. When the torque applied on the pushing wheel from the front speed reduction gear cannot overcome the resistant force from the torsion spring and the compression spring, the shifting gear is in its first stage of speed status and is engaged with the first planet gears and the second planet gears. When the torque applied onto the pushing wheel overcomes the resistant force from the torsion spring and the compression spring, the pushing wheel rotates and drives the clamp to rotate the shifting gear, and the shifting gear is not rotated due to the engagement of the notches and the protrusions. The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of an automatic speed shifting device constructed in accordance with the present invention; FIG. 2 is a cross-sectional view of the automatic speed shifting device in a first stage; FIG. 3 is a cross-sectional view of the automatic speed shifting device in a second stage; FIG. 4A shows a front view of the speed shifting device of the present invention at the first stage of speed, FIG. 4B shows a right side view of the speed shifting device of the present invention in the first stage; and FIG. 4C shows a left side view of the speed shifting device of the present invention in the second stage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, an automatic speed shifting device of the present invention comprises a frame 1 , a torque feedback device 2 and the transmission device 3 . The frame 1 is a cylindrical case and has a hollow chamber 11 . A plurality of protrusions 11 a extends from an inside of the chamber 11 . A plurality of triangle shaped slots 12 is defined through the wall of the frame 1 in the longitudinal direction and each slot 12 includes a peak portion and a base from which two recesses 12 a are defined in communication with two ends of the base. A plurality of ridges 13 extends from an outer surface of the frame 1 and is located close to the base of the slots 12 . A slit 14 is defined in the wall of the open end of the chamber 11 and a radial groove 15 defined through the wall of the frame 1 . The torque feedback device 2 includes a torsion spring 21 , a pushing wheel 22 , a C-shaped clamp 24 and a compression spring 25 . The pushing wheel 22 has a lever 22 a extending from an outer surface thereof, and inner threads 22 b are defined in an inner periphery of the pushing wheel 22 . A surface groove 22 c is defined longitudinally in the outer surface of the pushing wheel 22 . A plurality of lugs 24 a extends from an outer surface of the clamp 24 and a plurality of pin holes 24 b is defined through the clamp 24 and located corresponding to the slots 12 in the frame 1 . Each pin hole 24 b receives a pin 24 c . An elongate hole 24 d is defined through the clamp 24 and located corresponding to the radial groove 15 and the lever 22 a . The compression spring 25 is mounted to the frame and retained between the ridges 13 of the frame 1 and the lugs 24 a of the clamp 24 . The compression spring 25 is deformable by movement of the clamp 24 in the axial direction. The torsion spring 21 has a first end 21 a that is engaged with the surface groove 2 c of the pushing wheel 22 , and a second end 21 b that is engaged with the slit 14 of the frame 1 so as to maintain the pushing wheel 22 to face the frame 1 . The transmission device 3 includes an input gear 31 , a front speed reduction gear 32 , a shifting gear 33 and a rear speed reduction gear 34 . The input gear 31 is connected to an input power source that is not shown. The front speed reduction gear 32 includes a plurality of planet gears 32 a on one side thereof and a driving gear 32 b on the other side of the front speed reduction gear 32 so as to transmit power to the rear speed reduction gear 34 . The planet gears 32 a are engaged with inner teeth 22 b of the pushing wheel 22 and the input gear 31 so as to form a planetary speed reduction mechanism. The shifting gear 33 has an annular groove 33 a in an outer surface thereof and a plurality of notches 33 b are defined in the outer surface of an end of the shifting gear 233 . The pins 24 c extend through the slots 12 in the frame 1 and are engaged with the annular grooves 33 a . The protrusions 11 a of the frame 1 are engaged with the notches 33 b . The rear speed reduction gear 34 is a disk and is connected to a plurality of planet gears 34 a on one end and the other end of the disk is connected to an output gear 34 b so as to transmit power to an output mechanism that is not shown. The planet gears 34 a are engaged with the drive gear 32 b and the inner teeth of the shifting gear 33 . The receiving chamber 11 receives the transmission device 3 and the torque feedback device 2 in sequence. In a first stage of speed, the clamp 24 is retained by the torsion spring 25 and the pins 24 c are located at the peak portion of the slots 12 , and the pins 24 c are engaged with the annular groove 33 a of the shifting gear 33 , so that the shifting gear 33 is located at a top most position. As shown in FIGS. 4A and 4B, the lever 22 a of the pushing wheel 22 is engaged with the radial groove 15 of the frame 1 so that the rotation angle is limited. The angle of the lever 22 a is also limited by the retaining of the torsion spring 21 and the clamp 24 . Referring to FIGS. 3, 4 A, 4 B, and 4 C, when the a large resistant torque is applied, the input gear 31 of the transmission mechanism 3 increases the torque of the front speed reduction gear 32 gradually so that the planet gears 32 a of the front speed reduction gear 32 apply an reaction force in reverse direction to the inner threads 22 b of the pushing wheel 22 so as to rotate the pushing wheel 22 . Nevertheless, the pushing wheel 22 rotates only when the force of the torsion spring 21 and the force of the compressing spring 25 are overcome. When the pushing wheel 22 rotates, the lever 22 a drives the clamp 24 via the elongate hole 24 d . When the clamp 24 rotates, the pins 24 c are lowered along the inclined surface of the radial groove 15 in the frame 1 so that the clamp 24 depresses the compression spring 25 . Under the circumstance, the pins 24 c drive the shifting gear 33 downward till the torque that the front speed reduction gear 32 applies onto the pushing wheel 22 reaches a pre-set value, the pushing wheel 22 rotates a largest angle. The shifting gear 33 reaches the lower most position and the notches 33 b are engaged with the protrusions 11 a of the frame 1 . The torque of the shifting speed reduction mechanism can be decided by choosing proper torsion spring 21 and the compression spring 25 . The automatic shifting device can be used as a power transmission device in electric drills. When drilling, if a small amount of torque is required, the torque applied on the pushing wheel 22 from the front speed reduction gear 32 cannot overcome the resistant force from the torsion spring 21 and the compression spring 25 , so that the pushing wheel 22 does not rotate. The shifting gear 33 is in its first stage and is engaged with the planet gears 34 a of the rear speed reduction gear 34 and the front speed reduction gear 32 . The shifting gear 33 provides a first stage when the front speed reduction gear 32 co-rotates with the rear speed reduction gear 34 . The result is located in the maximum value of the curve of the torque vs. revolution. If a large torque is required, the input gear 31 increases the torque gradually and the torque applied onto the pushing wheel 22 from the front speed reduction gear 32 overcomes the resistant force from the torsion spring 21 and the compression spring 25 . The number of the revolution of the pushing wheel 22 increases when the torque increases and the shifting gear 33 is in its lower most position and disengages from the front speed reduction gear 32 . In the meanwhile, the shifting gear 33 is still engaged with the planet gears 34 a of the rear speed reduction gear 34 . The shifting gear 33 is not rotated due to the engagement of the notches 33 b and the protrusions 11 a . This provides the first stage of speed and the result is located in the maximum value of the curve of the torque vs. revolution. While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.	An automatic speed shifting device includes a frame having a transmission device and a torque feedback device received therein. The torque feedback device has a torque resistant member so that when the load torque is smaller than its resistant torque, the speed reduction mechanism of the transmission device is remained at the first stage speed status. When the load torque is larger than its resistant torque, a pushing wheel devices a clamp to compress a shifting gear so that the speed reduction mechanism is shifted to another stage of speed. The speed reduction mechanism of the transmission device automatically shifts the speed reduction mechanism when the load torque increases or reduces such that the mechanical efficiency of the transmission device can be increased.	5
Botanical/commercial classification: Rosa hybrida /Hybrid Tea Rose Plant. Varietal denomination: cv. ‘Meilabasun’. SUMMARY OF THE INVENTION The new variety of Hybrid Tea rose plant was discovered at Le Cannet des Maures, Var, France, while growing among a group of plants of the ‘Meilambra’ variety (non-patented in the United States). The plant displayed distinctive yellow flowers that are margined and suffused with red unlike those of its parent, and is considered to be a mutation of unknown causation of the ‘Meilambra’ variety. Had the plant of the new variety not been discovered, preserved, and subsequently studied to confirm its characteristics, it would have been lost to mankind. It was found that the Hybrid Tea rose plant of the present invention possesses the following combination of characteristics: (a) exhibits an erect growth habit, (b) forms in abundance on a nearly continuous basis attractive yellow blossoms that are margined and suffused with red, (c) forms attractive dense dark green and glossy foliage that contrasts well with the blossom coloration, and (d) is particularly well suited for cut flower production under greenhouse growing conditions. The tolerance to disease is very good particularly with respect to Oidium and Botrytis. The new variety of the present invention can be readily distinguished from its parental ‘Meliambra’ variety. More specifically, the ‘Meilambra’ variety forms bicolored blossoms that are red on the upper surface and yellow on the under surface of the petals. The new variety performs well under greenhouse growing conditions while producing cut flowers. The new variety has been found to undergo asexual propagation in France by a number of routes, including budding, grafting, and cuttage. Asexual propagation by the above-mentioned techniques in France has confirmed that the characteristics of the new variety are stable and are strictly transmissible by such asexual propagation from one generation to another. The new variety has been named the ‘Meilabasun’. BRIEF DESCRIPTION OF THE PHOTOGRAPH The accompanying photograph shows as nearly true as it is reasonably possible to make the same, in a color illustration of this character, a typical specimen of the new variety. The rose plant of the new variety was one year of age and was observed during June while budded on Rosa indica major understock and growing under greenhouse conditions at Le Cannet des Maures, Var, France. Elegant blossoms in various stages of opening as well as the dark green and glossy foliage are shown. DETAILED DESCRIPTION The chart used in the identification of the colors is that of The Royal Horticultural Society (R.H.S. Colour Chart). The description is based on the observation of one-year-old plants during June while budded on Rosa indica major understock and growing under greenhouse conditions at Le Cannet des Maures, Var, France. Class: Hybrid Tea. Plant: Height. —When pruned to a height of 85 cm, floral stems having lengths of approximately 70 to 80 cm commonly are produced. A typical plant height is approximately 170 cm. Width. —A typical plant width has not been determined since the erect plant is primarily grown in greenhouses for cut flower production. Habit. —Erect. Branches: Color. —Young stems: near Green Group 137A and 137B. Adult wood: near Green Group 137B and 137C. Thorns. —Configuration: rather longish pointed, curved downwards on the upper surface, and concave on the under surface. Size: approximately 0.5 cm in length on average with an ovate base on young stems, and approximately 0.9 cm in length on average with an ovate base on adult stems. Quantity: approximately 4 on average over a young stem length of 15 cm, and approximately 10 on average over an adult stem length of 15 cm. Color: near Green Group 143C on young stems, and near Green Group 143C on adult stems. Prickles. —Size: approximately 0.2 cm in length on average with an ovate base on young stems, and approximately 0.4 cm in length on average with an ovate base on adult stems. Quantity: approximately 10 on average over a stem length of 15 cm on young stems, and approximately 7 on average over a stem length of 15 cm on adult stems. Color: near Green Group 143C on young stems, and near Green Group 143C on adult stems. Leaves: Stipules. —Smooth, adnate, pectinate, broad, approximately 2 cm in length on average, approximately 0.3 cm in width on average, near Yellow-Green Group 147A on the upper surface, and near Yellow-Green Group 147B on the under surface. Petioles. —Upper surface: near Green-Group 137A and 137B. Under surface: near Green-Group 137A and 137B. Length: approximately 3.4 cm on average. Diameter: Approximately 0.2 cm on average. Rachis. —Upper surface: near Green Group 137A and 137B. Under surface: near Green Group 137A and 137B. Length: approximately 5.4 cm on average. Diameter: approximately 0.1 cm on average. Leaflets. —Number: 3, 5 (most often), and 7. Shape: ovate with a symmetrical tip and a cordate base. Apex: sometimes slightly cuspidate and symmetrical. Serration: single and fine (as illustrated). Texture: firm, and glossy. General appearance: dense and dark green. Size: terminal leaflets commonly measure approximately 7.2 cm in length, and approximately 5.3 cm in width. Color (young foliage): Upper surface: near Green Group 139A. Under surface: near Yellow-Green Group 147B. Color (adult foliage): Upper surface: near Yellow-Green Group 147A. Under surface: near Yellow Green Group 147B. Inflorescence: Number of flowers. —Commonly one flower per stem. Peduncle. —Smooth, year Yellow-Green Group 144A in coloration, approximately 2.5 cm in length on average, and approximately 0.5 cm in diameter on average. Sepals. —Upper surface: tomentose, and near Yellow-Green Group 144B in coloration. Under surface: tomentose, and near Yellow-Green Group 144A in coloration. Length: approximately 3 cm on average. Width: approximately 1.5 cm on average. Shape: longish pointed and narrow with a straight base. Extensions: commonly three sepals possess very weak extensions and two sepals commonly possess no extensions. Buds. —Shape: conical. Size: medium. Length: approximately 5 cm on average. Width: approximately 2.8 cm on average. Color as the calyx breaks: Upper surface: near Yellow Group 7A and amply margined and suffused with Red Group 46B. Under surface: near Yellow Group 6A margined with Red Group 46A. Flower. —Shape: high-pointed, and during opening the central petals assume a somewhat pointed configuration and extend above the outer petals. Diameter: approximately 12 cm on average when open. Color (in the course of opening): Upper surface: near Yellow Group 7A margined with Red Group 46C. Under surface: near Yellow Group 8C, amply suffused with Yellow Group 8A, and slightly margined with Red Group 45D. Basal color spot: none. Color (when open): Upper surface: near Yellow Group 4D, amply margined with Red Group 53C and 53D and slightly suffused with Red Group 53D. Under surface: near Yellow Group 4D, suffused with Yellow Group 3D, and slightly margined with Red Group 53D. Basal color spot: near Yellow Group 8A on upper surface only. Lasting quality: very long and commonly approximately 15 days on average on the plant and approximately 12 days on average when out and placed in a vase. Petal number: commonly approximately 25 on average under normal growing conditions. Petal arrangement: imbricated. Petaloids: none observed. Petal shape: oval, broader than length, flattened rounded base, rounded reflexed tip, approximately 4.3 cm in length on average, and approximately 6 cm in width on average. Petal margin: entire, slightly ruffled, and soft. Petal texture: consistent. Petal drop: good, the petals commonly detach cleanly before drying. Fragrance: none. Stamen number: approximately 170 on average. Anthers: near Yellow-Orange Group 18A in coloration, approximately 3 mm in length, and regularly arranged around the styles. Filaments: near Yellow Group 12A in coloration, and approximately 0.4 cm in length. Pistils: approximately 110 on average. Stigmas: near Yellow-Orange Group 15D in coloration, and approximately 0.1 cm in size on average. Styles: near Yellow Group 12C and 12D in coloration, and the length is approximately 0.5 cm on average. Receptacle: Shape: pitched-shaped in longitudinal section. Length: approximately 1 cm on average. Width: approximately 1 cm on average. Texture: smooth. Color: near Yellow-Green Group 144A. Hips: none observed to date under greenhouse growing conditions. Development: Vegetation. —Strong. Blooming. —Early, abundant and nearly continuous. Tolerance to diseases. —Very good with respect to Oidium and Botrytis. Aptitude to forcing. —Very good.	A new and distinct variety of rose plant of the Hybrid Tea Class is provided which abundantly forms on a nearly continuous basis attractive yellow blossoms that are margined and suffused with red. The growth habit is erect. Attractive dense dark green and glossy foliage is formed that contrasts nicely with the blossoms coloration. Tolerance to disease is good particularly with respect to Oidium and Botrytis. The new variety forces well under greenhouse growing conditions and is well suited for cut flower production under such conditions.	0
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a process for bleaching pulp without using organic chlorine compounds but still achieving levels of brightness required by the market e.g. 85-90 ISO. Before bleaching, pulp is continuously digested in a modified continuous cooking (MCC) digester (e.g. that described in U.S. Pat. No. 5,080,755 and U.S. patent application, Ser. No. 08/051,396 each incorporated by reference, herein). Subsequent to MCC digestion, the pulp undergoes oxygen-delignification in a modified continuous (MC) oxygen delignification process (e.g. that described in U.S. Pat. No. 3,963,561, incorporated by reference herein), until a low lignin level is achieved, e.g. low Kappa numbers of 10 or less. The novel process not only achieves good brightness and low lignin levels without using organic chlorides to bleach, but allows for very low levels of bleaching liquid discharge such that total filtrate, from washing of pulp during the bleaching process, that leaves the bleaching plant may be limited to 3 to 10 tons of liquid per ton of 90% pulp. Essentially, the novel process comprises treating the delignified pulp with sulfuric acid and a chelating agent such as EDTA, washing pulp in a single or double-diffuser washing tower (e.g., that described in U.S. Pat. No. 3,348,390 (single diffuser) and U.S. Pat. Nos. 3,563,891, 4,840,047 and 4,971,694 (double-diffusers), each of the foregoing patents' disclosures are incorporated by reference, herein), bleaching the pulp with hydrogen peroxide in a single or double-diffuser washing tower, adding sulfuric acid and ozone with mixing, reacting ozone with the pulp in a reaction vessel, and washing the ozone reacted pulp in a washing tower, wherein liquid filtrates from the aforesaid washing steps are recirculated to earlier washing steps and where single or double-diffuser washing steps have a high efficiency of at least 85%. 2. Description of the Prior Art The environmental protection authorities are making ever more stringent demands on the pulp industry to decrease the use of chlorine gas in bleaching. Permitted discharges of organic halogen compounds (AOX) in the waste water from bleaching plants have been gradually lowered and are now at such a low level that the pulp factories have in many cases stopped using chlorine gas. Instead, only chlorine dioxide is used as a bleaching agent. In achieving the same bleaching effect, chlorine dioxide forms smaller quantities of AOX than does chlorine gas. However, the polluting effects of chlorine dioxide have likewise been questioned. On the one hand, the environmental protection authorities in certain countries require that the discharges of organic chlorine compounds be reduced to such a low level that the requirements can hardly be fulfilled even if only chlorine dioxide is used for bleaching. On the other hand, environmental movements in several countries, in particular in Germany, have persuaded consumers to demand paper products which have been bleached entirely without using either chlorine gas or chlorine dioxide. The pulp industry is therefore searching for methods which permit pulp to be bleached without using these chemicals. One such method has been developed by the Swedish company Eka, which supplies bleaching chemicals to the pulp industry. The bleaching method, which is called LIGNOX (e.g. as described in SE-A-8902058), involves the unbleached pulp being first delignified with oxygen and then, after washing, being treated with EDTA, or other suitable chelating agent, in order to remove heavy metals bound within the pulp. The EDTA treatment stage (denoted as Q state, hereafter) is followed by an intensive bleaching stage with peroxide (denoted as P stage, hereafter), i.e. hydrogen peroxide. The charge of hydrogen peroxide (H 2 O 2 ) employed is relatively high, 15-35 kg per ton of pulp, depending on the brightness required and on the bleachability of the pulp. The time is quite long, 4 hours or longer, and the temperature high, 80°-90° C. However, the LGNOX method only provides a limited increase in brightness. Maximum brightness depends on the bleachability of the pulp and the charge of peroxide. Brightness in the region of 80-82 ISO has been achieved using the LIGNOX method. To achieve higher levels of brightness, further bleaching stages are required over and above the peroxide stage. In this connection, ozone is an interesting bleaching chemical. At least one experiment has shown that if an ozone bleaching stage (denoted Z stage, hereafter) is introduced after a peroxide stage, a significant increase in brightness is achieved while at the same time lignin content of the pulp is decreased. The latter point is important, since a pulp bleached with only peroxide or oxygen/peroxide still contains a relatively high content of lignin, which affects the brightness reversion tendency of the pulp. When high lignin content pulp is warmed or irradiated with sunlight, the pulp yellows. If ozone is used, further lignin is removed, resulting in the brightness of the pulp becoming more stable. A.G. Lenzing (See EP-A-441 113) has demonstrated how an ozone stage after a peroxide stage increases the brightness of sulphite pulp. If a peroxide stage is allowed to follow the ozone stage, a further increase in brightness is obtained. Eka has shown that this is also the case for sulphate pulp. Oxygen-bleached sulphate pulp was treated with EDTA to remove heavy metals and subsequently the pulp was bleached with peroxide and ozone according to the stage sequence QPZ. With this sequence, brightness in the region of 82-87 ISO was achieved, depending on the type of pulp. By extending the bleaching sequence with a further peroxide stage and bleaching according to the stage sequence QPZP, brightness in the region of 87-89 ISO was obtained, depending on the type of pulp, See "Non Chlorine Bleaching," J. Basta, L. Andersson, W. Hermanson; Proceedings Mar. 2-5, 1992--Westin Resort--Hilton Head--South Carolina; Copyright by Miller Freeman, Inc. Thus, it is possible, using process stage sequences QPZ and QPZP, to achieve the levels of brightness which the market requires for paper pulp, i.e., 87 ISO and higher, without using chlorine-containing bleaching agents. This provides interesting perspectives regarding both the effect of cellulose factories on the environment and the possibility of satisfying the demands of consumers for access to chlorine-free bleached pulps. A prerequisite for achieving high levels of brightness while using moderate quantities of bleaching agents is that, prior to bleaching, the pulp should have been delignified to low kappa numbers, at least lower than kappa number 16. Normally, a deterioration in quality, in particular loss of fiber strength, is obtained if the delignification in the digester house and oxygen-delignification are taken too far. However, using the modified digestion methods which have been developed in recent years, it has been found possible to achieve very low kappa numbers without loss of strength. For example, it is possible, using a modification of Kamyr's continuous digestion processor or modified continuous cooking (MCC) as described in U.S. Pat. No. 5,080,755 and U.S. patent application Ser. No. 08/051,396, combined with modified continuous oxygen-delignification, e.g. that described in U.S. Pat. No. 3,963,561, to achieve and go below kappa number 10 with softwood, and kappa number 8 with hardwood, while retaining their strength properties. The modification of the MCC process involves the "Hi-heat" washing zone in the lower part of the continuous digester also being utilized for counter-current digestion (See for example U.S. patent application Ser. No. 07/583,043, incorporated by reference herein). This is achieved by heating to the full digestion temperature in the "Hi-heat" circulation and adding alkaline digestion liquid to this circulation. The total digestion time in countercurrent is thereby extended to 3-4 hours as compared with about 1 hour in conventional MCC. In this way a very low concentration or lignin is achieved by the end of the digestion, which provides improved selectivity in the delignification, i.e. the lignin of the wood is efficiently eliminated without the cellulose being significantly affected. The digestion and oxygen-delignification can thus be carried out to very low kappa numbers without impairing the properties of the pulp. SUMMARY OF THE INVENTION The present invention provides a novel process for bleaching pulp without chlorine containing chemicals and for greatly reducing total washing filtrate discharge from the bleaching plant. The process is carried out in a bleaching plant using washing presses and/or single-diffusers (one-stage diffusers) and/or double-diffusers (two-stage diffusers) washers. The novel process comprises the steps of: 1. sending pulp, that has been subjected to continuous digestion and then oxygen-delignification and then washing in a washing apparatus, through a washing press; 2. treating, with agitation, the delignified washed pulp with sulfuric acid and a chelating agent; 3. washing the pulp in a washing apparatus; 4. bleaching with hydrogen peroxide in a reaction vessel; 5. washing the hydrogen peroxide bleached pulp in a washing apparatus; 6. adding sulfuric acid and ozone with mixing of the pulp; 7. reacting the pulp with ozone in a reaction vessel; 8. washing the ozone reacted pulp in a washing apparatus; wherein the majority of liquid filtrate from the bleaching process that is waste not to be recycled is drawn off from the washing apparatus of step 3, the washings in step 3 and 5 have at least 85% efficiency, filtrate from washing step 5 is recirculated and used as washing liquid for the washing apparatus of step 3, and filtrate from the washing apparatus of step 8 is recirculated and used in the washing apparatus for the washing of pulp after oxygen-delignification. Alternately, the novel process may use an additional bleaching step 9 of bleaching with hydrogen peroxide using a peroxide charge of e.g. 1-3 kg. per ton of pulp and washing the pulp after it receives a second hydrogen peroxide bleaching, in a washing apparatus, e.g. a washing press, a single-diffuser washer, or double-diffuser washer, wherein the majority of liquid filtrate from the bleaching process that is waste not to be recycled is drawn off from the washing apparatus of step 3, the washings in step 3 and 5 have at least 85% efficiency, the filtrate from washing step 5 is recirculated and used as washing liquid for the washing apparatus of step 3, the filtrate from the washing apparatus of step 8 is recirculated and used in the washing apparatus for the washing of pulp after oxygen-delignification, and the filtrate from the step 9 washing is recirculated and used as washing liquid in the ozone washing of step 8. The washing apparatus used in steps 3, 5, 8, and 9, mentioned above may be selected from the group consisting of a washing press, a single-diffuser washer, or a double-diffuser washer. Preferably a single-diffuser is used most preferably a double-diffuser is used. A further alternative bleaching step 9 is bleaching the pulp with hydrogen sulphite and washing in a washing apparatus, e.g. a washing press, a single-diffuser washer, or a double-diffuser washer: preferably a single diffuser, most preferably a double-diffuser. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic of a preferred pulp line for the process of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a plant is shown, which is constructed for the process steps of the present invention. The bleaching plant consists of a transport conduit 1 for pulp which is indicated throughout FIG. 1 as a conduit in solid line, and which at the beginning of the bleaching plant leads to a washing process 2. Subsequently there is a chute and medium consistency (MC) pump (as described in U.S. Pat. Nos. 4,854,819 and 4,976,586 each incorporated by reference, herein) with inlet conduits 4 and 5 for the incorporation of EDTA (Q-stage) and sulfuric acid. Also included in this Q-stage are a storage tower 6 with agitator 6A and a chute with an MC pump 6B. Next there is a washing tower 7 comprising a double-diffuser, which can be a KAMYR washing apparatus as described in U.S. Pat. Nos. 3,563,891, 4,840,047, 4,971,694, each incorporated by reference, herein, or as described in Ullman's, Encyclopedia of Industrial Chemistry, v. A18 p. 573 VCH Publishers 1991 Library Congress No. 84-25-829. From this washing tower 7 the filtrate being voided from the bleaching point is drawn off via conduit 8. After the washing tower 7 there is a chute with an MC pump in which vigorous admixture of peroxide (H 2 O 2 ), for a P-stage, takes place via conduit 10. Usually NaOH is added here, as well, in order to adjust the pH to the desired level. Next comes the reaction vessel 11 for the P-stage, which vessel is fitted at the top with a double-diffuser washer. After the P-stage there is a chute with a medium consistency (MC) pump with a supply conduit 14 for vigorous admixture of sulfuric acid. Then there is a mixer unit 16 for incorporating ozone gas (03), for the Z-stage, via conduit 15. Next there is a reaction vessel 17 for the pulp with the ozone, which vessel is connected by its upper attachment to a chute with a cyclone arrangement 18 in the upper part of which the ozone is drawn off in order to be rendered harmless in an ozone destroyer. The pulp, on the other hand, continues downwards and is pumped onwards to a second washing tower 20. Backwater, at a temperature of about 50° C., is appropriately employed as the washing liquid in the last washing tower 20. Fresh water is taken into the system, e.g., at a temperature of about 45° C., via a conduit 19 which leads to the P-stage bleaching tower 11 and there feeds washing liquid to the double-diffuser, preferably to the double-diffuser's second stage. An additional contribution can, if necessary, also be obtained from the last washing tower 20 via conduit 21A. The filtrate from the second stage of the P-stage bleaching tower 11 double-diffuser is recirculated, as washing liquid, via conduit 13 to the first stage in this double diffuser. The filtrate from this double diffuser, in the P-stage bleaching tower 11, is led away via a conduit 12 which is attached to a heat exchanger, which exchanger is fed with steam 12A so that the filtrate is pre-heated before it is conveyed to the double-diffuser (preferably the second stage) in the first washing tower 7. Here too, recirculation occurs from the second diffuser stage to the first via a conduit 9. For the purpose of pH adjustment, sulfuric acid can be added to said recirculation conduit 9 via a separate conduit 9A. The small amount of waste liquid which is drawn off from the bleaching plant is taken out from the first washing tower 7 double-diffuser via a conduit 8 from the first stage of the diffuser. If required, a separate conduit 8A can be taken from this waste conduit 8 to the washing press 2 for diluting the pulp after the washing press 2. This dilution liquid can also be obtained from the last washing tower 20 via conduit 21 and 2B. The filtrate from the washing tower 20 may be employed as washing liquid in the washing press 2 and in this case is conducted onwards via a separate conduit 2A. The filtrate from the washing press 2 is taken out via conduit 3 in order to be used in the oxygen-delignification stage. An indication of how a supplementary bleaching stage can be added in the event that even greater brightness is required is given in FIG. 1 by the conduit shown as a broken line from X to Y. In the preferred embodiment shown in FIG. 1, the fourth stage comprises an additional P-stage, so that a QPZP bleaching sequence is obtained. Like the P-stage described previously, admixture of hydrogen peroxide (and optionally NaOH as well) occurs in a chute with attached MC pump via a conduit 22, after which the pulp is pumped to the bleaching tower 23, which is at the bottom of a reaction vessel and is fitted at the top with a washing diffuser. The wash water for the washing diffuser is appropriately, as in the above-described case, backwater at about 50° C., which is supplied via conduit 25. The filtrate from the wash is then led away via a heat exchanger, which is attached to the outlet conduit 24, and is led, at the appropriate temperature, into the washing tower 20, where it is used as washing liquid. In a pulp line with a bleaching plant as described above, fully bleached pulp with a brightness of 85-90 ISO can be produced without using chlorine-containing chemicals. The volume of waste water from the bleaching plant can be kept at a very low level, 5 to 10 tons per ton of pulp and possibly as low as about 3 tons of waste water per ton of pulp. Apart from foreign substances, such as metal ions, released in the Q-stage, the waste water only contains organic substances, released in the peroxide and ozone stages, and spent bleaching chemicals supplied to the bleaching plant, i.e. mainly sodium (Na + ) and sulphate ions (SO 4 - ) . The composition of the dry substance of the bleaching plant filtrate is to a large extent the same as that of spent digestion liquid (black liquor) from the digester. It can therefore either be added to the black liquor or in some other way introduced into the chemical recovery system of the factory. For optimal heat economy, the bleaching-plant filtrate should be wholly or partially concentrated, for example by evaporation of freeze-crystallization, before it is introduced into the recovery system. A part of the liquid can, if required, be employed, even without concentration, for dissolving the chemical smelt originating from the soda furnace. Heavy metals released in the bleaching stage are efficiently separated off by precipitation in the green liquor clarification or filtration. Any possible excess of sodium and/or sulphur is removed in a known manner, for example by bleeding off from the chemical cycle, or is employed as alkali (NaOH) in the bleaching plant after complete oxidation of the sodium sulphide (Na 2 S), present in the white liquor, to sodium sulphate (Na 2 SO 4 ). In order to achieve the lowest possible consumption of chemicals and heat energy and the best possible quality of pulp in association with the lowest possible quantity of waste discharge from the bleaching plant, it is important that the bleaching plant system is configured in the correct manner with regard to water management and washing efficiency after the individual bleaching stages. Laboratory experiments have shown that the washing efficiency after the Q-stage should be at least 85%, preferably 90-95%, (determined according to the equation 100(X-Y)/X, where X is the quantity of undesirable substance before washing and Y is the quantity of the said substance remaining after washing, for a given amount of pulp) in order to be able to achieve high brightness and the best possible pulp viscosity in the subsequent peroxide stage(s). The reason for this is that even small quantities of metal ions in the peroxide stage cause decomposition of peroxide, which on the one hand increases consumption of peroxide and on the other lowers pulp viscosity. Additional comments concerning a bleaching plant according to FIG. 1 are given below, as, in some measure, are directions regarding alternatives to the preferred embodiment shown in FIG. 1. FIG. 1 shows a two-stage washing apparatus after the Q-stage, (e.g., A KAMYR, 2-stage double-diffuser). The washing efficiency with this apparatus is most preferred about 95%. In this double-diffuser, the filtrate from the subsequent peroxide bleaching stage is used as the washing liquid. The additional displacement is about 2 tons of liquid per ton of pulp. If the pulp concentration in the Q-stage is 10%, the amount of liquid employed is preferably 9 tons per ton of dry pulp. With the additional displacement, the total discharge from the Q-stage becomes about 11 tons of liquid per ton of dry pulp. This quantity of filtrate is the only filtrate leaving the beaching system. It contains released organic substances from the P- and Z-stages, including spent bleaching chemicals and heavy metals released in the Q-stage. The filtrate can be concentrated by evaporation, for example by mechanical vapor compression at reduced pressure. The filtrate can also be concentrated by freeze-crystallization, in which pure water crystals are formed and are separated off while released dry matter remains in the enriched filtrate, which can be conducted to the recovery system of the factory. The recovery system can vary. For example, a portion of the filtrate can be used for dissolving the soda smelt from the recovery boiler. The remainder of the filtrate can be concentrated and mixed with the black liquor. If required, the whole of the filtrate can be subjected to a limited pre-evaporation or freeze-crystallization to a liquid quantity which is adapted to the maximum quantity which can be fed to the soda dissolvers. Alternatively, the whole of the filtrate can be pre-evaporated to the lowest possible quantity of liquid, which is then mixed with the black liquor, which goes to the usual evaporation system of the factory. In order to limit energy consumption in the pre-evaporation stages or in the freeze-crystallization system, the quantity of filtrate leaving the washing apparatus of the Q-stage can be decreased by reusing a portion of this filtrate as dilution liquid prior to the Q-stage. In this case, to achieve a balance in liquid management, the supply of fresh water to the washing apparatus of the peroxide stage must be decreased to a corresponding degree and replaced with recirculated filtrate from the ozone stage. The degree of closure (recirculation) which is possible will depend on how many metal ions are introduced in the Q-stage together with the oxygen-delignified pulp. As a result of the closure, an enrichment of both metal ions and released organic substances occurs in the filtrate of the Q-stage. Owing to this, the washing losses are increased over to the peroxide stage, which, if excessive, can impair the bleaching result. For pulps which do not have too high a content of heavy metals, and at low kappa numbers, the discharge from the Q-stage can be decreased to about 3 tons per ton of pulp by recirculation. In this way, a substantial decrease is obtained in necessary energy consumption in the pre-evaporation or freeze-crystallization systems. The supply of fresh water to the washing apparatus of the peroxide stage must be decreased to a corresponding degree and replaced with re-circulated filtrate from the Z-stage. The peroxide stage is carried out at high temperature preferably 70°-90° C. while the temperature in the subsequent ozone stage should be about 40°-50° C. and not exceed about 50° C., in order to avoid too great a decrease in the viscosity, and hence the strength, of the bleached pulp. To avoid transfer of hot liquid from the peroxide stage to the ozone stage, the thermal efficiency in the washing apparatus after the peroxide stage should be high, at least 85%, and preferably 90% or as high as 95%. Additionally, it is important that the carryover to the ozone stage of dry material and residual chemicals released in the peroxide stage be as small as possible. Otherwise, ozone is consumed in the oxidation of material already released from the pulp instead of releasing further lignin from the pulp fiber. For this reason, too, the degree of washing after the peroxide stage should be as high as possible and at least 85% but preferably 90% and more preferred 95%. A third basis for efficient washing after the peroxide stage is that unused peroxide, H 2 O 2 , is effectively recirculated to the beginning of the peroxide stage by using filtrate from the washing stage after the peroxide stage as washing liquid for the washing apparatus after the Q-stage. Preferably a KAMYR a single or double-diffuser is used as the washing apparatus after the peroxide stage. Preferably, the washer apparatus provides a total washing efficiency of about 95% and thereby fulfills requirements for washing efficiency. Most preferably a double-diffuser is used. Besides efficient temperature regulation, decreased carryover of released dry material, and recirculation of residual chemicals, there is also achieved improved heat economy by enclosing the peroxide stage between two washing devices of high washing efficiency. By raising the thermal efficiency from 85% to about 95%, the quantity of steam required for the heat exchange for filtrate from the washing apparatus after the peroxide stage, used for the washing apparatus after the Q-stage, can be decreased by more than 30%. When using alkaline filtrate from the peroxide stage as washing liquid for the washing apparatus after the Q-stage, there is a risk of re-precipitation of metal ions which have been chelated with EDTA. To achieve the best result, the pH in the Q-stage should preferably be 5-6. The filtrate from the peroxide stage preferably has a pH of 10-11. The risk of re-precipitation can be substantially decreased by carrying out the wash after the Q-stage in two steps and by limiting the quantity of alkaline liquid which is transferred to the first washing stage to the dilution factor, i.e. about 2 tons. In order completely to eliminate any possible effect of this relatively low input of alkali, the washing liquid from stage P recirculated to stage Q can be neutralized by the addition of sulfuric acid (H 2 SO 4 ). Preferably, pure water at a temperature of 40°-45° C. is used as the washing liquid for the washing apparatus of the peroxide stage. If the thermal efficiency of the wash is sufficiently high, 90-95%, the temperature of the ozone stage is preferably 45°-50° C. A higher temperature should be avoided in order to decrease the risk of impairing the quality of the pulp. The pH of the pulp suspension in the ozone stage is preferably pH 2.0-3.0. This is achieved by adding sulfuric acid, H 2 SO 2 , to the pulp prior to the ozone stage. The filtrate which is drawn off from the wash after the ozone stage thus has a correspondingly low pH. This filtrate is suitable for adding to the last washing apparatus after the oxygen-delignification stage. This apparatus should preferably be a washing press or other apparatus which gives an outgoing pulp consistency in the region of 20-35%. The filtrate of the ozone stage can be used partly as washing liquid for the washing press and partly for diluting the pulp consistency entering the Q-stage from 20-35% to about 10%. That part of the filtrate of the ozone stage which is used as washing liquid is preferably neutralized to about pH 6 in order to avoid lignin re-precipitation in the washing system after the oxygen-delignification stage. As has been pointed out previously, the pH in the Q-stage is preferably pH 5-6. If required, additional sulfuric acid is added to adjust the pH. If, on dilution with the pulp from the last washing stage after oxygen-delignification, the acid filtrate from the ozone stage causes a lower pH than about 5, it may become necessary to add alkali (NaOH) to adjust to a pH of 5-6. If the bleaching is concluded after the ozone stage and is limited to the sequence QPZ, backwater from a drying machine or possibly fresh water at a temperature of 40°-60° C., preferably 45°-55° C., is supplied to the washing apparatus after the ozone stage. This apparatus can have a somewhat lower washing efficiency than the washers of the Q- and P-stages, steps 3 and 5, respectively. In FIG. 1, a one-stage diffuser has been included which gives a washing efficiency of 85-90%. To stabilize the brightness of the pulp and destroy residual ozone after the ozone stage, sulphur dioxide can, if required, be supplied to the pulp suspension after the ozone-stage reactor but before the washing apparatus of this stage. If required, alkali (NaOH) is also added for neutralization to pH 5-6. If the highest brightness, 88-90 ISO, is required, an additional peroxide stage can be introduced after the ozone stage. The bleaching sequence then becomes QPZP. The last peroxide stage preferably has a temperature of 50°-65° C. The charge of peroxide used is preferably low, 1-3 kg H 2 O 2 per ton of pulp. The washing after the P-stage can be carried out, for example, by a one-stage diffuser. The filtrate from this washing apparatus is used as the washing liquid for the washing apparatus after the ozone stage. The washing liquid used can be backwater from the drying machine or pure washing water at a temperature of 45°-55° C. The invention will be more completely understood by reference to the following examples. EXAMPLE 1 A softwood sulphate pulp prepared in a pulp line using modified MCC digestion and subsequently oxygen-delignified to a kappa number of about 12 with a viscosity of 1020 dm 3 /kg, was treated with EDTA at 70° C. for 60 minutes. The charge of EDTA was 2 kg per ton of dry pulp and the pH of the liquid was about 6. After the treatment, the mixture was diluted with pure water and the pulp was pressed to different dry matter contents so that washing efficiencies of 85%, 90% and 95% were obtained. Pulps containing 15%, 10% and 5% of filtrate from the original EDTA-stage were subsequently bleached under conditions which were otherwise identical with 35 kg H 2 O 2 per ton of pulp at 90° C. for 270 minutes and at a pH of about 11. TABLE 1______________________________________Washing H.sub.2 O used Kappa Brightness Viscosityefficiency kg.sup.2 BDMT number % ISO dm.sup.3 /kg______________________________________85 34.5 5.1 74.7 84790 34.3 5.0 75.0 82895 31.0 4.6 77.7 869______________________________________ As is evident from Table 1, the washing efficiency of 95% gives the best result for the process, with the lowest consumption of chemicals and the lowest kappa number, i.e. the most effective delignification and the greatest brightness together with the highest pulp viscosity, i.e. with the least effect on the cellulose. The results indicate that the washing efficiency should be 90-95%. It should be pointed out, however, that pulps with lower initial content of heavy metals may give a good bleaching result even with lower washing efficiencies. Nevertheless, the washing efficiency should not fall below about 85%. In order to achieve this result, the washing equipment after the Q-stage should give at least this efficiency, though 90-95% efficiency is preferred. Bleaching conditions such as chemical charge, reaction temperature, dwell time, etc., will vary depending on that bleachability of the oxygen-bleached pulp. Example 2, below, demonstrates the difference between two different pulps, a pulp produced from Scandinavian softwood and a hardwood pulp produced from eucalyptus wood. EXAMPLE 2 Softwood and Eucalyptus wood were prepared in a pulp line using modified MCC digestion and subsequent oxygen-delignification according to the preferred embodiment of the present invention as noted above and in Table 2 below, where Table 2 reports viscosity, pH, temperatures, amounts of reagents, and brightness results. TABLE 2______________________________________ Softwood Eucalyptus______________________________________kappa number after 12 7.4oxygen stageViscosity dm.sup.3 /kg 1020 998Q-stageEDTA kg/ADMT 2.0 2.0pH 6 5.4P1-stageH.sub.2 O.sub.2 kg/ADMT 35 20NaOH kg/ADMT 25 18Temperature °C. 90 80pH 11.0 11.3Viscosity dm.sup.3 /kg 895 932Brightness, ISO 78.1 81.8Z-stageOzone O.sub.3 kg/ADMT 4.7 3.9pH 2.4 2.8Viscosity dm.sup.3 /kg 791 761Brightness, ISO 86.5 89.4P2-stageH2O2 kg/ADMT 2 --NaOH kg/ADMT 4 0Temperature °C. 70 --pH 10 --Viscosity dm.sup.3 /kg 755 --Brightness, ISO 90.2 --______________________________________ As is evident from Table 2, for softwood pulp four bleaching stages with the sequence QPZP are required in order to achieve a brightness of 90 ISO, while with eucalyptus wood virtually the same brightness is achieved with only three bleaching stages, QPZ. In addition the consumption of bleaching agents is lower for this latter pulp type. This is due partly to the lower initial kappa number, but also to the fact that this type of pulp is easier to bleach even when starting from the same kappa number. For softwood, the amount of COD, Na + and dry matter (DM) in the combined filtrates from the different bleaching stages was Using the described method of water management, and depending on the degree of closure and the quantity of filtrate going to evaporation and hence to chemical recovery, the following concentrations are obtained in the filtrate for 5 tons of filtrate per ton of pulp and 10 tons of filtrate per ton of pulp, respectively ______________________________________Quantity of filtrate COD Na.sup.+ DMton/ADMT % % %______________________________________5.0 1.90 0.77 0.4610.0 0.98 0.39 0.23______________________________________ It is evident that the concentration of dry matter in the filtrate is quite low, about 1% in the case of 10 tons of filtrate per ton of pulp and about 2% if the quantity of filtrate is decreased to 5 tons/ton of pulp. If the quantity of filtrate is decreased by evaporation or freeze-crystallization to 0.5 tons per ton of pulp, the corresponding concentration then becomes about 16%, i.e. about the same concentration as in the black liquor which goes for evaporation. The increased load on the evaporation plant, which 0.5 tons of extra filtrate represents, should in most cases not cause any problems with capacity. The proposed system should thus provide favorable conditions for solving the problem of restricting the effluent systems of the pulp factories and thereby radically decreasing environmental pollution. It will be evident to the person skilled in the art that practice of the invention is not limited to that which has been described above. Thus, it is, for example, possible for the dry matter in the drawn-off filtrate to be concentrated by other methods, e.g. by osmosis, etc. In other respects as well, it is evident that the person skilled in the art can employ various types of apparatus to achieve what is sought by the invention, for example other known washing devices can be used, such as a pressure diffuser, filter, etc., as alternatives to the washing press (before the Q-stage). In addition, washing presses can be used instead of diffusers at certain points, for example, after the Q-stage and/or the P-stage. Furthermore, it is possible to use something other than a P-stage as the fourth bleaching stage, for example a hydrogen sulphite-stage.	A process is disclosed for bleaching pulp without chlorine containing chemicals and for greatly reducing total washing filtrate discharge, comprising the steps of: 1) sending pulp that has been subjected to continuous digestion, oxygen-delignification and then washing, through a washing press; 2) treating, with agitation, the delignified washed pulp with sulfuric acid and a chelating agent; 3) washing the pulp in a washing apparatus; 4) bleaching with hydrogen peroxide in a reaction vessel; 5) washing the hydrogen peroxide bleached pulp; 6) adding sulfuric acid and ozone with mixing of the pulp; 7) reacting the pulp with ozone in a reaction vessel; and 8) washing the ozone reacted pulp, wherein the majority of liquid filtrate from the bleaching process that is waste not to be recycled is drawn off from the washing apparatus of step 3, the washings in step 3 and 5 have at least 85% efficiency, filtrate from washing step 5 is recirculated to the washing apparatus of step 3, and filtrate from the washing apparatus of step 8 is recirculated and used in the washing apparatus for the washing of pulp after oxygen-delignification.	3
[0001] The invention is related to the tempering section of a flat glass tempering furnace, in which the glass is oscillated on rollers. Nozzle boxes, from which jets of air are blown onto the glass are parallel to the rollers. BACKGROUND OF THE INVENTION [0002] It is well known that the tempering machine loading efficiency in average is no more than about 65% of the maximum loading area. The reason for this waste area is, of course, that glass sizes vary and whole tempering section loading area cannot be utilized. That means high waste of energy and also unnecessarily high peak power. [0003] A standard practice is that tempering blower blows air into a so-called pressure equalization tank, which is as long as tempering section. The air pressure is stabilized in the tank essentially onto the static pressure. From the tank air is passed through hoses, nozzle boxes and nozzles onto the glass. The nozzles cover the entire surface area of the tempering section. Tempering section energy consumption and the need for peak power is always according to the whole tempering section area and as required for each glass thickness. All of these devices, the fan, the pressure equalization tank, hoses, and tempering section are generally on floor level. They therefore require quite a wide floor area. A separate pressure equalization tank, hoses and nozzle boxes also cause pressure losses. [0004] Peak power demand is known to be reduced by e.g. in such a way that air is blown only to the first half of the tempering section. In this area especially thin glasses are tempered, because they require a high tempering pressure. Also other more complex peak power reduction methods have been developed, such as e.g. Finnish patent F1 100525 B. However, even for these the problem is that the tempering area is of fixed size. They are not adjustable according to the use of the machine. The waste area of 35 per cent, therefore, remains the same. In particular, the width of the tempering area is not adjustable by known methods. Especially the tempering width should be adjusted, because the tempering length is approximately 2.5 times the width, so the energy saving potential for the width is 2.5 times higher than for the length. IMPROVED INNOVATIVE METHOD [0005] This innovative solution substantially improves the effective loading area percentage reducing the blowing area of the glass tempering and/or the cooling zone when the entire loading area cannot be filled quite completely. The invention reduces the energy consumption and the peak power in the same proportion as the blowing area can be closed. The invention also discloses novel, advantageous and low-cost ways to achieve these objectives. The method according to the invention is characterized by what is presented in the patent claims. BRIEF DESCRIPTION OF THE DRAWINGS [0006] In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which [0007] FIG. 1 is a schematic top (or bottom) view of a glass tempering or tempering and cooling area, [0008] FIG. 2 is a schematic side view of an end part of a tempering section, [0009] FIG. 3 schematically shows a first embodiment relating to FIG. 2 , [0010] FIG. 4 schematically shows a second embodiment relating to FIG. 2 , [0011] FIG. 5 schematically shows a third embodiment relating to FIG. 2 and [0012] FIG. 6 is a schematic side view of a tempering section. DETAILED DESCRIPTION OF THE INVENTION [0013] FIG. 1 illustrates a glass tempering or tempering and cooling area seen from the top (or bottom). Glass enters into the tempering section from direction Ge. The total area is the W×L=A. The air entrances into the nozzle boxes can be closed in the width direction in the area 2×Bd×L thus saving tempering or cooling energy and peak power accordingly. It is also possible to shut down the length of the nozzle boxes from one side only, thus saving half of the energy, in the area of Bd×L. [0014] In the length direction it is possible to build a wall, where the last nozzle boxes of the tempering section are isolated from the rest of tempering section, in which case the glass loading area can be shortened by the length of Ld. [0015] The rest of the drawing describes the multi-purpose way to improve the tempering section. A known method is to make so-called “by pass” tempering section for thin glass, which is a high pressure part about 1.5 m long (Lhp), followed by a cooling section, which is specially designed for glass cooling. They often have their own fans. The patent application FI20030942 describes an alternative where a single fan is used in both sections. However, the tempering section of FI20030942 is not multi-purpose, since the cooling section is specifically designed for cooling only. In contrast, FIG. 1 illustrates a multi-function tempering section, because all nozzle boxes are at the same distance from each other and also nozzles have the same C-C distances. High pressure area is Thp, (Lhp×B or Lhp×Bs). The air from fan B 1 or fans B 1 nd BL 2 is led mainly into the high pressure area Thp by damper/or dampers Sh 1 Sh 2 where it tempers the glass, but part of the air is passed to second section to the length Ls or Lss, where it cools the glass. When the glass load has passed through the Thp section and thus has been tempered, the total air delivery of the fan(s) can be directed into the cooling section lengths Ls or Lss. [0016] When tempering thicker glasses, it is possible to use for tempering and after-cooling lengths L and Lhp+Lss. [0017] The air supply ducts Ad of drawing 1 are attached to the fan(s) B 1 , (BL 2 ), and the feed openings of pressure equalization chamber Ps with flexible joints Aif. Below Ps will simply be referred to as pressure chamber. The joints are also shown in FIG. 2 , section A-A 3 . The design allows the distance adjustment of the top and the bottom nozzles to the glass as required by the thickness of the glass tempered. It also allows the upper and lower portions of the tempering section to “yawn”, that means driving the nozzles up and down for broken glass removal and maintenance. Air supply to the pressure chambers Bs can be taken, except for the side, also from the top and bottom in which case flexible connection Aif should be axial. [0018] FIG. 2 is the tempering section side view, especially its end part. Glass G enters into the tempering section carried by rollers R from Ge direction. Air from the fan(s) is blown through duct(s) and opening(s) Ai into the pressure chambers Ps, from where it proceeds to the nozzle boxes Nb, and further to the nozzles, which are machined nozzle covers, Nc. From the nozzles air jets J discharged onto the glass. The AA-sections 1 , 2 , 3 of drawing 2 show how the tempering and/or cooling zones may be split to areas, into which air flow can be closed ( FIGS. 3, 4 and 5 ). The easiest way to accomplish this is by building air tight dividing walls W into the nozzle boxes. In this way the ends of the nozzle boxes can be separated by the dividing walls from the center of the nozzle boxes. Shut-off device Sh can be used to close the air entering the into the ends of nozzle boxes and nozzles at the length of Bd. In all sections A-A the tempering width is reduced from dimension B to dimension Bs. The number of walls W may be increased, in which case it would be possible increase number of tempering areas and reduce blowing onto unnecessary area. Shutting devices can be various designs, sliding, pivoting, etc. [0019] Item W 1 is a dividing wall which separates the end of the tempering section (pressure chamber Ps and the nozzle boxes Nb) into an independent section. Aia is air inlet opening with shutting device for this section. The shutting device may optionally be in the wall W 1 . [0020] By building pressure chambers Ps together with the nozzle boxes Nb, a separate pressure equalizing tank between the fan/fans and tempering section can be eliminated. Elimination of a separate tank and hoses also reduces pressure losses. [0021] The heights of the nozzle boxes are increased from the center of the tempering section towards the sides. This improves the air escape from the tempering section. Also the glass, which sometimes breaks in the tempering section, is easier to remove move. The air supply openings Ai and Aia and shutter devise Sh may also be located above and below. [0022] Sections A-A 1 and A-A 2 illustrate how the pressure chamber Ps can be divided into separate parts. The access of the air can be prevented into the nozzle boxes in area marked by Nbs by shutting devices Sh. In section A-A 3 pressure chamber is common for all nozzle boxes to the width B and shut-off device Sh closes the air from entering into the nozzle boxes at the width of Bd. [0023] The loading conveyor of the tempering machine must be marked for the areas corresponding to the selection of the smaller tempering areas as used for each case. If desired, there is also possibility to build automation for this part. [0024] The walls W needed are not just a cost burden, because they also bind the nozzle box walls together and prevent nozzle box walls from bulging outwards due to the air pressure. Building the pressure chamber together with the nozzle boxes also saves factory space and reduces manufacturing and transport expenses. [0025] FIG. 6 illustrates a complete tempering section. Pressure chambers Ps are “self-supporting” because of box design. By erecting columns C on the floor it is possible to design guiding devices for upper Lu and lower L 1 tempering sections. Guiding devices can be rolls, slides or similar. Any types of drives, Cw, (screws, chain wheels etc.) can move guiding devices and consequently upper and lower tempering sections up and down. FIG. 6 shows service position. This design would avoid overhead lifting devices and further reduce use of manufacturing material and labor as well as transportation space from the manufacturer to the erection site.	Tempering section of a flat glass tempering machine saves energy and reduces peak power by shutting an area of tempering section in the areas where there is no glass. The tempering section is multipurpose so that the first part can be used as a high pressure section for tempering thin glasses, latter section being after the cooling section. Further, the high pressure section can use air produced by a blower and/or compressor. The tempering section includes rollers transporting glass, upper and lower pressure chambers, nozzle boxes attached to them, nozzle covers with nozzles and necessary shutting devices and internal walls.	2
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of the following provisional application that is hereby incorporated by reference in its entirety: [0002] U.S. Provisional App. No. 60/825,870 filed Sep. 15, 2006. BACKGROUND [0003] 1. Field [0004] This invention generally relates to electronic gaming and particularly relates to tracking the use of electronic games and other digital media. [0005] 2. Description of the Related Art [0006] Handheld electronic game platforms frequently use proprietary platforms that limit the available community of sponsors and in turn limit the number of available games and related media. Due to the proprietary nature of game platforms, many game developers do not have access to the platforms without working out costly and complex business arrangements with the providers of the proprietary electronic game platforms. Game developers and users have found electronic games to by an excellent source of entertainment and skill develop that should be available without the constraints described above. Game developers and users may also desire access to free or low cost games that provide a level of visualization and challenge similar to the proprietary games. Therefore, a need exists for methods and systems that allow the development of games and related media by a wider community of sponsors, while supporting measured distribution and/or use of the games to allow for methods and systems that reward content providers for usage of the games. SUMMARY [0007] An electronic game tracking platform may facilitate deployment, use, and sponsoring of electronic games in a manner that avoids limitations associated with proprietary solutions. The electronic game tracking platform may provide a basis for rewarding game developers, sponsors, and the like. The platform may further provide methods and systems for game assessment, feedback, market research, trial offers, subscription, pay-per-use and the like. An electronic game tracking platform may be embodied as a game console, handheld game, handheld game controller, a USB dongle, electronic components within a standard computing facility, software deployed on a gaming device or computer, and the like. [0008] An electronic game tracking platform may facilitate tracking aspects of a game, such as a count of executions that may include the number of times the game is played, the duration of time a game is played, a count of game events (such as number of laps completed, levels completed, opponents defeated, items captured, property accumulated, goals achieved, items acquired, challenges overcome, lives lost, levels failed, times defeated, items lost, property lost, goals not achieved, and a wide range of other game events), processor time used, or the like. An electronic game tracking platform may facilitate local and on-line gaming, including multi-player games, online interactive games, sample games, downloaded games, uploading games, and the like. Access to games, features of games, and repeated use of a game may be enabled by the methods and systems provided by the electronic game tracking platform. [0009] The electronic game tracking platform may facilitate aspects of social networking, such as determining membership in online clubs, access to individuals' online information associated with a social networking site or page, distribution and tracking of games offered through social networking sites, and the like. [0010] In an aspect of the invention, a method includes providing an electronic game program; providing tracking criteria associated with game activity occurring over a network; tracking one or more game events associated with the tracking criteria to provide a tracking report; and transmitting a tracking report signal over the network. [0011] In the method, the electronic game program includes a tracking program for providing the report. The electronic game program is an open-source program. [0012] In the method, the tracking criteria are transmitted over the network. [0013] In the method, the activity occurring over the network includes one or more of a request for online game play, accessing a network resource, an online participant interacting with the game, downloading a game, uploading a game, sending a tracking report, requesting access to a feature of the game, and downloading a feature of the game. [0014] In the method, the tracking criteria include at least two of a game execution, game time, and a game event. Game time includes one or more of an accumulation of time the game is played, duration of a game execution, and a percent of idle time during a game execution. A game event is selected from the group consisting of downloading a game, uploading a game, starting a game, ending a game, pausing a game, defeating an opponent, capturing a game item, accumulating a game property, attempting a game level, completing a game level, achieving a goal, overcoming a challenge, loosing a game life, defeat, losing items, losing acquired property, reaching a game start count threshold, accessing a game feature, and adding a game participant to a game execution session. [0015] In the method, transmitting the report signal is based on a comparison of the tracked game events with a tracking criteria threshold. The threshold is one or more of a number of game starts, a number of online participants, a number of requests for online participation, completing a game level, and completing a game [0016] The method further includes transmitting the report over the network in response to a request from a network resource. Transmitting the report includes transmitting a request to download a new game. [0017] In the method, the report includes data representing the tracked events. [0018] In another aspect of the invention, a system includes a networked electronic game facility for executing a electronic game program; tracking criteria associated with game activity occurring over the network; a transaction facility for tracking one or more game events associated with the tracking criteria to provide a tracking report; and a report signal associated with an aspect of the report, wherein the electronic game facility transmits the report signal over the network. [0019] In the system, the electronic game program includes a tracking program for providing the report. In the system, the electronic game program is an open-source program. The system further includes a host for transmitting the tracking criteria over the network. [0020] In the system, activity occurring over the network includes one or more of a request for online game play, accessing a network resource, an online participant interacting with the game, downloading a game, uploading a game, sending a tracking report, requesting access to a feature of the game, and downloading a feature of the game. [0021] In the system, the tracking criteria include at least two of a game execution, game time, and a game event. Game time includes one or more of an accumulation of time the game is played, duration of a game execution, and a percent of idle time during a game execution. A game event is selected from the group consisting of downloading a game, uploading a game, starting a game, ending a game, pausing a game, defeating an opponent, capturing a game item, accumulating a game property, attempting a game level, completing a game level, achieving a goal, overcoming a challenge, loosing a game life, defeat, losing items, losing acquired property, reaching a game start count threshold, accessing a game feature, and adding a game participant to a game execution session. [0022] In the system, the aspect of the report is a comparison of the tracked game events with a tracking criteria threshold. The threshold is one or more of a number of game starts, a number of online participants, a number of requests for online participation, completing a game level, and completing a game. [0023] The system further includes a network resource for requesting the game facility to transmit the report. [0024] In the system, the report includes a request to download a new game. [0025] These and other systems, methods, objects, features, and advantages of the present invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings. All documents mentioned herein are hereby incorporated in their entirety by reference. BRIEF DESCRIPTION OF THE FIGURES [0026] The invention and the following detailed description of certain embodiments thereof may be understood by reference to the following figures: [0027] FIG. 1 depicts an architecture of an electronic game platform. [0028] FIG. 2 depicts an aspect of the game platform that is removable. [0029] FIG. 3 depicts an online electronic game tracking embodiment. [0030] FIG. 4 depicts a plurality of electronic game tracking facilities, associated tracking reports, and a relationship between the games and sponsors of the games. DETAILED DESCRIPTION [0031] Referring to FIG. 1 , aspects of an electronic game platform, including a handheld facility 102 for receiving and executing a game program, will be described. Additional aspects may include an external memory device 202 for storing and tracking game program execution, methods and systems for accessing a code associated with a game program, methods and systems for recording execution of a game program, and methods and systems for tracking execution of aspect of a game program, and for controlling execution of a game. These and other aspects provide a foundation for an electronic gaming platform that may facilitate game execution tracking and restriction. [0032] Architecture of an electronic game platform 100 of the invention may include a handheld facility 102 for receiving and executing a game program. The handheld facility 102 may include a CPU 104 , memory 106 , operating system 108 , screen 110 , video out 112 , USB port 114 , input control device 118 (e.g. button, keyboard, mouse, pointer), a wired interface for an input control device 120 , wireless interface for an input control device 122 , a battery 124 , and a power port 128 . The handheld facility 102 may further include a transaction facility 130 . [0033] The handheld facility 102 may receive electronic games through the USB port 114 or a network port 132 for purposes of executing the electronic games. The games may be embodied in the form of a computer program that is stored in the memory 106 and executed by the CPU 104 and O/S 108 . [0034] A user of the handheld facility 102 may interact with the facility 102 through the input control 118 and the screen 110 . Alternative to, or in addition to the input control 118 , the user may interface a wired remote input control 120 or a wireless 122 remote input control to the handheld facility 102 . Alternative to, or in addition to the screen 110 , the user may access the video out 112 for displaying remotely. These interface alternatives provide flexibility and facilitate use of the handheld facility 102 in a variety of environments. [0035] A transaction facility 130 may be associated with the CPU 104 to facilitate tracking the execution of an electronic game by the handheld facility 102 . The transaction facility 130 may facilitate recording each time an electronic game is executed by identifying an aspect of the game during execution. An example of an aspect may include a code which is known to the transaction facility 130 and presented to the transaction facility 130 during execution. The transaction facility 130 may directly record and retain a record of each execution of a game. The transaction facility 130 may directly record a count of the executions of a game. A count of executions may include the number of times the game is played, the duration of time a game is played, a count of game events (such as number of laps completed, levels completed, opponents defeated, items captured, property accumulated, goals achieved, items acquired, challenges overcome, lives lost, levels failed, times defeated, items lost, property lost, goals not achieved, and a wide range of other game events), processor time used, or the like. The count of executions associated with the game by the operating system may be compared to a permitted count, such as stopping play when a particular count level has been reached. The allowed count level may be varied, such as in response to game events, payments, or the like, such as allowing extended game play upon making a payment or completing a level of the game. [0036] The handheld facility 102 may include a transactional facility for making payments, such as credit card payments or other electronic payments, including through the interface with the portable, external memory device. [0037] The transaction facility 130 may provide a response to the CPU 104 upon receiving the code so that the CPU 104 may record either a record of each game execution or a count of game executions or other type of count (or some combination of the same). The memory 106 may maintain the record, perhaps in response to a signal from the CPU 104 . The memory 106 may be non-volatile in that it may retain the record of execution even when power from the power port 128 and the battery 124 is not present. [0038] The transaction facility 130 may further interact with the electronic game program so that uses of aspects of the game may also be tracked. This feature may facilitate tracking when one or more screens of the game are viewed, when more than one user simultaneously interfaces with the handheld facility 102 , and the like, including any of the types of counts described herein. [0039] The transaction facility 130 may further facilitate restricting use of a game on the handheld facility 102 based on an aspect of the game. The transaction facility 130 may provide a signal to the CPU 104 when a predetermined number of executions of the game have been recorded so that the CPU 104 may alert the user. Reaching the predetermined number of executions may result in the user having to take another action, such as and without limitation making a payment, providing information to continue executing the game, and so on. [0040] The transaction facility 130 may facilitate controlled use of a game on the handheld facility 102 by comparing a code associated with the game with a code known to the transaction facility 130 and then signaling the CPU 104 if an aspect of the codes do not match. The code known to the transaction facility 130 may be configured through the handheld facility 102 by receiving the code and/or a program associated with the code through the USB 114 or network 132 ports. In an example, the code and/or program associated with the code may be presented to the handheld facility 102 by a server or other computing facility on the network 132 such as the Internet. In another example, a device connected to the USB port 114 may include the code and/or a program associated with the code. The handheld facility 102 may access the device on the USB port 114 to retrieve the code and/or program. Components of a transaction facility may reside in the operating system of the handheld facility 102 , in the portable, external memory device, or in a remote computer, such as a server with ecommerce capability, or in a combination of the foregoing. [0041] The code may be configured into the transaction facility 130 by the CPU 104 . The transaction facility 130 may include a non-volatile memory for the code so that configuring the code only once is required. Alternatively, the code may be configured into the transaction facility by the CPU 104 at various times such as at power-on of the handheld facility 102 . The code configured by the CPU 104 may be temporary such that the code is erased when power is removed. [0042] The transaction facility 130 may be a physical aspect of the handheld facility 102 or it may be a software aspect such as a program or portion of the OS 108 executing on the handheld facility 102 . The transaction facility may be a software service, such as a web service, deployed in a service oriented architecture, where some component of the transaction facility is accessed via a computer network, such as upon connection of the portable, external memory device to a computer that is connected to a network. [0043] By using a code as herein described, the handheld facility 102 may facilitate use of game programs that enforce digital rights management. Alternatively, the transaction facility 130 may track execution of game programs without digital rights management. The code may facilitate tracking by uniquely identifying the game program being executed. The handheld facility 102 may support game programs such as open source programs. [0044] FIG. 2 depicts another aspect of the electronic game platform 100 in which an external, portable memory device 202 (such as and without limitation an USB device) may be adapted to track if/when a host computing facility such as the handheld facility 102 accesses a code that is stored in the memory device 202 . The external memory device 202 may further include a controller 204 and a memory 208 . The memory 208 may be a non-volatile memory as shown in FIG. 2 . Alternatively, the memory may include volatile and non-volatile portions. The controller 204 may facilitate access to the memory 208 through the host port 210 . [0045] The controller 204 may support functions associated with accessing the memory 208 from the host port 210 . In an example, the controller 204 may monitor access to the memory 208 such that accesses to a code stored in the memory 208 may be detected by the controller 204 . The code may be associated with a game program. The game program may be executed by a host computing facility that may access the device 202 through the host port 210 . [0046] The controller 204 may facilitate tracking the execution of an electronic game by a host computing facility. The controller 204 may facilitate recording each time an electronic game is executed by identifying an aspect of the game during execution. An example of an aspect may include a code which is known to the controller 204 and presented to the controller 204 during execution. The code may be presented to the controller 204 by a host accessing the code in the memory 208 of the device 202 . The controller 204 may directly record and retain a record of each execution of a game in the memory 208 . The controller 204 may directly record a count of the executions of a game in the memory 208 . [0047] The controller 204 may provide a response to a host so that the host may record either a record of each game execution or a count of game executions or both. [0048] The controller 204 may further interact with a host executing an electronic game program so that uses of aspects of the game may also be tracked. This feature may facilitate tracking when one or more screens of the game are viewed, when more than one user plays the game, and the like. The controller 204 may track the use of these and other features when the host accesses the memory device 202 . The game program may be adapted to access the memory device 202 as needed to support tracking use of aspects of the game. [0049] The controller 204 may further facilitate controlling use of a game on the host based on an aspect of the game. The controller 204 may provide a signal to the host when a predetermined number of executions of the game have been recorded so that the host may alert the user. Reaching the predetermined number of executions may result in the user having to take another action, such as making a payment or providing information to continue executing the game. [0050] The controller 204 may facilitate restricting use of a game on the host by comparing a code associated with the game with a code known to the controller 204 and signaling the host if an aspect of the codes does not match. The code known to the controller 204 may be stored in the memory 208 of the memory device 202 . The code associated with the game may be provided by the host over the host port 210 . [0051] The code known to the controller 204 may be configured by the host by writing the code to the memory device 202 . The controller 204 may receive the code and/or a program associated with the code through the host port 210 . In an example, the code and/or program associated with the code may be presented to the memory device 202 by a host adapted to configure the memory device 202 . The host may be capable of executing a game program and configuring the memory device 202 through a USB port 114 as shown in FIG. 1 . [0052] The code may be stored from time to time in the memory device 202 by a host through the host port 210 to enable the memory device 202 to support other game programs. A plurality of codes may be stored in the memory device 202 such that a host accessing any of the codes may facilitate tracking and recording the execution of a game program on a host associated with the code. [0053] The memory device 202 may include a code, a game program, or a game program and a code. The code may be part of the game program. The game program and/or the code may be stored in the non-volatile portion of the memory device 202 . The host may access the game program, code, or both in the memory device 202 for purposes of executing the game program on the host. The controller 204 may record each access to the game program similarly to recording access to the code as herein described. A host may access the memory device 202 to store the game program, code, or both in the memory 208 . The memory device 202 may be removed from the host and connected to another host so that execution of the game program on the other host may be tracked or controlled as herein described. [0054] The memory device 202 may provide a report signal associated with the code or game program to the host through the host port 210 . The report signal may encompass information relating to tracking associated with the game program and/or code stored on the memory device 202 . The report signal may be related to a predetermined number of executions, or to an aspect of the game program as herein described. Alternatively, the signal may be related to a date, such as an expiration date associated with the execution of a game program tracked by the memory device 202 . The report signal may appear as a file in a file system of the memory device 202 . [0055] Each access by a computer program executing on a host (such as an electronic game program) to the code that is stored in the memory device 202 may trigger tracking of the access. In an example the controller 204 may record the access as well as other information such as time and date. The computer program may provide additional information such as a user name, a number of users, a source of the program, and the like that may be recorded by the controller 204 . The record may indicate that the program is running on a host computing facility. [0056] The memory device 202 may automatically send information based at least in part on a configuration of the memory 208 . The information may be associated with if/when a program that is stored in the memory device 202 is executed by a host computing facility. The host and/or the memory device 202 may generate the information. The host may be a handheld facility 102 , a personal computer, a home entertainment system, or any and all other such devices. [0057] It will be appreciated that the information, signals, and the like that may be provided by and/or stored in the memory device 202 , the transaction facility 130 , and so on may be communicated to the handheld facility 102 , the host, or any other such computing facility. Such information, signals, and the like may encompass or be associated with a unique signifier or identifier of a game, host, handheld facility 102 , and so on. Uses of such information, signals, and the like may be directed at preventing a game from be played in certain circumstances, on particular devices, and so on. Such information, signals, and the like may be directed at tracking interactions between a host, a handheld facility 102 , a game, and the like. Information related to the tracking of such interactions may be reported back to a host, a server computer, a website, and the like. Information related to the tracking of such interactions may encompass an indication of how much the game has been used. The information, signals, and the like may be associated with a memory device 202 . The information, signals, and the like may be associated with a transaction facility 130 of a handheld facility 102 . The information, signals, and the like may be associated with both a memory device 202 and a transaction facility 130 . Many other such embodiments will be appreciated and all such embodiments are within the scope of the present disclosure. [0058] Electronic game tracking improvements may be associated with online activity, such as internet activity. Online activity may include interactive game play, multi-user game play, downloading games, uploading games, downloading game updates and access codes, download of information representing game aspects to be tracked, social networking, and the like. [0059] FIG. 3 depicts an online electronic game tracking embodiment of the methods and systems herein described. Handheld facility 102 may connect through network port 132 to a server 310 that may include data storage facilities to store electronic games 314 and tracking reports 312 that may have been retrieved from the handheld facility 102 by the server 310 . The handheld facility 102 may include a transaction facility 130 that may track electronic games based on a tracking criterion 320 and/or a criteria tracking method 318 . Transaction facility 130 may use the criteria 320 and the tracking method 318 to track aspects of a game 302 , such as a first aspect 304 and a second aspect 308 that may be presented through the display 110 . The handheld facility 102 may be in communication with an external memory facility 202 through the USB port 114 . [0060] In embodiments described herein, the server 310 may interact with the handheld facility 102 (or another embodiment of electronic game tracking such as software running on a computing facility) to facilitate determining what criteria 320 and what criteria tracking method 318 to employ for tracking a game 302 . The server 310 may retrieve a tracking report 318 from the handheld facility 102 for storage in the report data facility 312 . The report 318 may include tracking results for game aspects 304 and 308 that relate to the tracking criteria 320 , and tracking data for the game aspects that relate to the tracking method 318 . In the example embodiment of FIG. 3 , game aspects 304 and 308 are defined by criteria 320 and the method of tracking 318 is to track a percent of user access to the tracked aspects. Handheld device may create report 318 and store it locally in memory 106 or external memory 202 so that it can be retrieved by server 310 . [0061] FIG. 4 depicts an embodiment of the methods and systems of electronic game tracking including a plurality of electronic game tracking facilities, associated tracking reports, and a relationship between the games and sponsors of the games. In FIG. 4 , game tracking facilities 402 , 404 , and 408 may be connected, such as through the internet to a server 310 that may store tracking reports 412 , 414 , 418 for one or more of the game tracking facilities in a report data storage facility 312 . Game sponsors 410 and 420 may be in communication with the server so that they can take advantage of the tracking reports related to games they sponsor. In FIG. 4 , game sponsor 410 may sponsor games 402 and 404 , while game sponsor 420 may sponsor game 408 . These sponsorships may be made known to server 310 so that server 310 can facilitate the game sponsors having access to (or receiving) reports associated with the games for which they have responsibility. Each game tracking facility 402 , 404 , and 408 may generate a tracking report ( 412 , 414 , 418 respectively) that may be retrieved by server 310 . Each game report may include game identification information (such as a game name, serial number, revision, and the like) that may be used by the server 310 , by the sponsors 410 , 420 , or by both to associate a tracking report with a sponsor. Game sponsors 410 and 420 may include game developers, promoters, market researchers, investors, individuals (e.g. through a social networking posting), clubs, and the like. [0062] Electronic game tracking improvements may be associated with interactive online game play. Tracking associated with online game play may include tracking requests for online game play, websites or URLs associated with online game play, a count and a record of online users participating in the online game play, features of the game accessed by online participants, time associated with game play sessions of online participants, and the like. A game that may be played through the handheld facility 102 or in association with the portable memory device 202 may be tracked so that online activity associated with the game is tracked. The information tracked may be useful for determining a popularity of the game or features of the game. Interactive online game play may be enabled by electronic game tracking by requiring online participants to provide information, such as demographics or identifying information to be associated with tracking of the online interactions. [0063] Users may request download of games. The request may be honored based on a usage or tracking report that may be generated by electronic game tracking. In an example, an electronic game may be provided in a series of linked downloads that require the gamer to achieve a level of performance or success with a download before being authorized to access a linked download. Electronic game tracking may count and record various game executions, completed levels, and the like and provide a report to a website offering game downloads. Based on, for example, the highest completed level provided in the report, a user may be allowed to access the next linked download of the game. [0064] A game sharing website, such as a site providing games for free may receive a user request to download a game. If the user request includes a game tracking/usage report generated with the electronic game tracking methods and systems herein described, the user may be offered a premium game or another option that may not be available to users that do not include game tracking reports in their download requests. In an example, a user may employ the methods and/or systems for electronic game tracking herein described on the user's home personal computer. The user may access a game website and request a game. During the course of interaction between the user and the website to process the request, the user may provide a game tracking report generated on the user's behalf. Alternatively, the website may download browser code, such as Java code, to the user's computer so that the downloaded code may automatically gather game tracking report information available on or through the user's computer. The downloaded browser code may interact with a game controller 102 or an external memory device 202 that is connected to and in communication with the web browser. [0065] In a similar way, game uploading may be enabled through use of aspects of the game tracking methods and systems herein described. Users may request to upload a game, such as a game the user has created or modified, or a game that has been provided to the user. The electronic game tracker may track and record requests to upload (and/or download) games so that a report of tracked users' game upload (download) activity may be provided to an internet connected server associated with game uploading. The report may also indicate a number of times a user has tested a game to be uploaded, thereby establishing credibility associated with the game upload. Electronic game tracking may record each level within a game that a user has successfully passed or tested, providing additional details about the game to be uploaded. Other information, such as how many online users have used the game to be uploaded may also be provided to the upload website. [0066] Electronic game tracking may be associated with online social networking. Social network participants may establish criteria associated with accessing aspects of their online social network information, such as electronic games, videos, and the like. The criteria may include requiring the game tracking methods and systems herein described to be deployed and executing on a user's computer to allow access. In an example, an online social network participant may post an electronic game in association with their online social network page that is available for download. A user may download a copy of the game if they agree to associate or have already associated the electronic game tracking technology herein described with their computing device to which the game is to be downloaded. In this way, the social network participant may track uses of the downloaded game. In another example of associating social networking with electronic game tracking, a user may establish a members-only online community for sharing games, other digital content, and the like. Membership may be based on presentation of an electronic game tracking report, and may be further based on information within the report. [0067] Aspects of electronic games may be enabled based on an association of the aspect of the game and electronic tracking. Aspects of games that may be enabled include access to characters, scenes, challenges, features such as saving and restoring a game, and the like. Electronic game tracking may include enabling or allowing access to aspects of electronic games based on certain criteria determined in association with electronic game tracking software or hardware. In an example, a game tracking controller 102 may include an access code that enables access the aspects or features. The user may be required to provide the access code to access the aspects or features. The game, or other software associated with the game tracking controller 102 may offer to provide the access code to the user in exchange for compensation, such as a payment, providing information, and the like. The user may receive the access code, or may receive access to the protected aspects or features, upon providing the information or payment. Payment may be a micro payment, a virtual currency payment, a real world payment, and the like. Information provided may include demographics associated with the user, a URL, a friend's email address, the user's email address, a survey response, and the like. [0068] Electronic game tracking may be associated with online identification of aspects of a game to track. While a wide variety of aspects of games may be tracked, identifying which specific aspects, of the many possible, should be tracked may be provided through an online interaction. A game sponsor or provider may incorporate or utilize electronic game tracking as herein described and may, from time to time, adjust the information tracked by providing information, such as in the form of a download, to game tracking software and/or hardware associated with a game that is related to the game web site. A game sponsor may provide aspects of a game that are related to an upcoming event, such as a presidential election. The game sponsor may provide an indication to electronic game tracking functionality to track user access to scenes or aspects of the game associated with the election until the election has occurred. After the election, the sponsor may provide an indication, such as through an online download, to the game tracking functionality to track different information. The game sponsor or other online party interested in game tracking may identify how an aspect is to be tracked. In an example, tracking presidential election scenes may be accumulated over a time frame such as a month when the election is a year away. The same tracking information may be accumulated over a shorter period of time, such as a week or a day as the election approaches. [0069] The electronic game tracking technology, such as embodied as the external memory tracker 202 may essentially provide transaction facility capabilities (such as game tracking) while interacting with a computing facility to which it is logically and/or physically attached. The computing facility may be a personal computer, server, game controller, game console, set-top box, remote control, and the like. The external memory 202 may be used with the game controller 102 so that one or more aspects of a game may be tracked simultaneously. Alternatively, the game controller 102 may not directly include the game tracking technology and may, instead, rely on the external memory 202 to provide tracking capability. [0070] Electronic game tracking may be associated with personal computers, web servers, and the like. In particular, electronic game tracking functionality may be associated with one or more operating systems such as MacOS, Linux, Windows, Vista, and the like. The game tracking technology may be adapted to provide a reliable, robust, easy to use interface that is associated with the operating system running on the computer or electronic device through which the electronic tracking is occurring. [0071] Electronic game tracking, such as embodied in a handheld facility 102 or enabled by external memory facility 202 , may be used for a variety of applications including market research, virtual e-commerce, digital rights management protection, other counting and tracking applications included herein, and the like. Game tracking information, such as may be included in a report described herein may be associated with similar reports from a variety of other electronic game tracking instances by, for example, a server that receives the reports over the internet. The associated reports may be analyzed to determine aspects of a population of electronic game players that may facilitate researching game player preferences, skill levels, and the like. In addition to the game tracking information, other information as may be collected by electronic game tracking, such as game identification information, IP address, and the like may be included in the report and included in market research. [0072] The elements depicted in flow charts and block diagrams throughout the figures imply logical boundaries between the elements. However, according to software or hardware engineering practices, the depicted elements and the functions thereof may be implemented as parts of a monolithic software structure, as standalone software modules, or as modules that employ external routines, code, services, and so forth, or any combination of these, and all such implementations are within the scope of the present disclosure. Thus, while the foregoing drawings and description set forth functional aspects of the disclosed systems, no particular arrangement of software for implementing these functional aspects should be inferred from these descriptions unless explicitly stated or otherwise clear from the context. [0073] Similarly, it will be appreciated that the various steps identified and described above may be varied, and that the order of steps may be adapted to particular applications of the techniques disclosed herein. All such variations and modifications are intended to fall within the scope of this disclosure. As such, the depiction and/or description of an order for various steps should not be understood to require a particular order of execution for those steps, unless required by a particular application, or explicitly stated or otherwise clear from the context. [0074] The methods or processes described above, and steps thereof, may be realized in hardware, software, or any combination of these suitable for a particular application. The hardware may include a general-purpose computer and/or dedicated computing device. The processes may be realized in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable device, along with internal and/or external memory. The processes may also, or instead, be embodied in an application specific integrated circuit, a programmable gate array, programmable array logic, or any other device or combination of devices that may be configured to process electronic signals. It will further be appreciated that one or more of the processes may be realized as computer executable code created using a structured programming language such as C, an object oriented programming language such as C++, or any other high-level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices, as well as heterogeneous combinations of processors, processor architectures, or combinations of different hardware and software. [0075] Thus, in one aspect, each method described above and combinations thereof may be embodied in computer executable code that, when executing on one or more computing devices, performs the steps thereof. In another aspect, the methods may be embodied in systems that perform the steps thereof, and may be distributed across devices in a number of ways, or all of the functionality may be integrated into a dedicated, standalone device or other hardware. In another aspect, means for performing the steps associated with the processes described above may include any of the hardware and/or software described above. All such permutations and combinations are intended to fall within the scope of the present disclosure. [0076] While the invention has been disclosed in connection with the preferred embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is not to be limited by the foregoing examples, but is to be understood in the broadest sense allowable by law. [0077] All documents referenced herein are hereby incorporated by reference.	Electronic game tracking in a networked environment facilitates deployment, use, and sponsoring of electronic games in a manner that avoids limitations associated with proprietary solutions. Networked electronic game tracking provides a basis for rewarding game developers, sponsors, game assessment, feedback, market research, trial offers, subscription, pay-per-use and the like. Networked electronic game tracking facilitates local and on-line gaming, including multi-player games, online interactive games, sample games, downloaded games, uploading games, and the like. Access to games, features of games, and repeated use of a game may be enabled by the methods and systems provided by electronic game tracking. Electronic game tracking facilitates aspects of social networking, such as determining membership in online clubs, access to individuals' online information associated with a social networking site or page, and distribution and tracking of games offered through social networking sites.	6
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application relies for priority upon Korean Patent Application No. 2009-114174 filed on Nov. 24, 2009, the contents of which are herein incorporated by reference in their entirety. BACKGROUND [0002] 1. Field of Disclosure [0003] The present disclosure of disclosure relates generally to light-emitting discharge tubes such as cold cathode fluorescent lamps used for light sources of liquid crystal displays, and more specifically to a lamp driving circuit used to selectively turn on and off the discharge tubes, and to a backlight unit having the lamp driving circuit, and to a liquid crystal display (LCD) using the same. [0004] 2. Description of Related Technology [0005] Conventionally, cold cathode fluorescent lamps (CCFLs) are used as backlighting light source for liquid crystal displays (LCDs), and inverter circuits are used within the LCD electronics to generate high voltage AC power for turning-on the CCFLs. Recently, a scanning control scheme has been proposed for inverter circuits so as to reduce power consumption of the backlight unit. According to the proposed scanning control scheme, a plurality of CCFLs are grouped into block units, and the on/off operation of each CCFL block is controlled through a time division scheme so that light which is not needed is not wastefully generated. [0006] The backlight unit employing the scanning control scheme includes CCFL blocks and a plurality of inverter circuits connected with the CCFL blocks. The high voltage lamps driving circuits are driven through a time division scheme according to control signals provided from an external control circuit to control the timing of turning on and off of lamps in the CCFL block. [0007] However, since the backlight unit employing the conventional scanning scheme requires as many individually controlled inverter circuits as there are in number the individually controllable lamps of the CCFL blocks, the manufacturing cost of the LCD is increased, and a mounting area for The high voltage lamps driving circuits is increased in proportion to the number and complexity of The high voltage lamps driving circuits used. In addition, the backlight unit employing the scanning control scheme requires additional circuits for the synchronization of operating frequencies of the high voltage lamps driving circuits and the phase synchronization of the CCFL blocks. Accordingly, a method of driving the backlight unit in this way becomes complicated and expensive and more prone to break down as complexity of the control circuits increases. SUMMARY [0008] Embodiments in accordance with the disclosure provide a lamp driving circuit capable of simplifying a configuration of a switching circuit. Embodiments in accordance with the disclosure provide an LCD using a backlight unit with the simplified controllable inverter circuit to reduce size, power consumption and price of the backlight unit. [0009] According to embodiments, a lamp driving circuit includes a high frequency isolation transformer and a low voltage switch circuit. A secondary winding of the isolation transformer is connected in series between a high voltage, high frequency power source and a load composed of one or more high voltage discharge tubes. Depending on the AC impedance provided by the secondary winding, a lamps igniting high frequency, high voltage AC signal will be applied or not applied to the discharge tubes and the lamps will light up or not light up accordingly. The switch circuit switches a state of a primary winding of the isolation transformer between first and second different impedance states, for example between an open circuit state and a short circuited state. The switch circuit responds to a low voltage control signal supplied from a controller that determines when and at what duty cycle the lamps will be driven. Since the switch circuit operates at low voltages, it can be made of relatively small and inexpensive circuit components. [0010] According to embodiments disclosed herein, a backlight unit includes a power source, a plurality of discharge tube blocks, a plurality of switch circuits, and a control circuit. Each discharge tube block has a plurality of discharge tubes. The isolation transformers are installed in correspondence with the discharge tube blocks, respectively. Secondary windings of the isolation transformers are connected in series between the high voltage power source and input terminals of the discharge tube blocks. The isolation transformers supply high AC voltage to the discharge tube blocks when the tubes are to be lit. The switch circuits are connected to primary windings of the isolation transformers, respectively, to switch a state of the primary windings for example between an open circuit state and a shorted circuit state according to a control signal. The control circuit generates the control signal to control a switching operation of the switch circuits. [0011] According to embodiments, a liquid crystal display includes a liquid crystal display panel and a backlight. The liquid crystal display panel includes a plurality of liquid crystal devices divided into a plurality of display regions to display an input image. The backlight is provided at a rear of the liquid crystal display panel. The backlight includes a power source, a plurality of discharge tube blocks, a plurality of isolation transformers, a plurality of switch circuits, and a control circuit. The discharge tube blocks include a plurality of discharge tubes and correspond to the display regions. The isolation transformers are installed corresponding to the discharge tube blocks, respectively. Secondary windings of the isolation transformers are connected in series between the power source and input terminals of the discharge tube blocks. The isolation transformers selectively supply high frequency AC voltage signals to the discharge tube blocks. The switch circuits are connected to primary windings of the isolation transformers, respectively, to switch a state of the primary windings to an open state or a short state according a control signal. The control circuit generates the control signal to control a switching operation of the switch circuits. [0012] As described above, the configuration of a circuit used to switch a plurality of CCFL blocks at a high speed is simplified to provide a lighting system driving circuit having small size, low power consumption, and low price and The high voltage lamps driving circuit is employed in the backlight unit and the LCD having a scanning control function for the CCFL blocks or a time control function for turn-on/turn-off operation of each CCFL block such that the size, power consumption and price of the backlight unit and the LCD can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The above and other advantages of the present disclosure will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: [0014] FIG. 1 is a circuit diagram schematically showing a backlight unit according to an embodiment of the present disclosure; [0015] FIG. 2A is a circuit diagram showing an equivalent circuit and its resonant frequency as it appears on the secondary winding side of the isolation transformer of FIG. 1 when the primary winding of the isolation transformer is in the open circuit state; [0016] FIG. 2B is a circuit diagram showing an equivalent circuit and its resonant frequency as it appears on the secondary winding side of the isolation transformer when the primary winding is shorted by an electronically controlled and low voltage switching circuit; [0017] FIG. 2C is a graph showing the variation in resonant frequency and inductance the secondary winding side equivalent circuit when the primary winding is switched from the opened state to the shorted state; [0018] FIG. 3A is a timing and waveforms view showing voltage waveforms at nodes N A and N B of FIG. 1 when the primary side switch is turned off (open circuit state); [0019] FIG. 3B is a timing and waveforms view showing voltage waveforms at the nodes N A and N B of FIG. 1 when the switch is turned on (closed circuit state); [0020] FIG. 4 is a table showing the relation between the variation in impedance values of the primary and secondary windings and the operating state of a CCFL block when the switch of FIG. 1 is turned on or off; [0021] FIG. 5 is a circuit diagram showing a backlight unit using series resonance occurring by an LC series resonant circuit in detail; [0022] FIG. 6A is a view showing the relation between variation in inductance values of the primary and secondary windings of the isolation transformer and the operating state of the CCFL block when FETs of FIG. 5 are turned on or off; [0023] FIG. 6B is a view showing variation in voltage and current when a backlight section of FIG. 5 is turned on/off; [0024] FIG. 7 is a circuit diagram showing a structure in which a TRIAC is connected as the switch of the backlight unit shown in FIG. 1 ; [0025] FIG. 8 is a circuit diagram showing a structure in which a photo-responsive TRIAC is connected as the switch of the backlight unit shown in FIG. 1 ; [0026] FIG. 9 is a circuit diagram showing a structure in which MOSFETs are connected as the switch of the backlight unit shown in FIG. 1 ; [0027] FIG. 10 is a circuit diagram showing a backlight unit according to another embodiment of the present disclosure in detail; [0028] FIG. 11 is a circuit diagram showing a backlight unit according to another embodiment of the present disclosure in detail; [0029] FIG. 12 is a circuit diagram showing a backlight unit according to another embodiment of the present disclosure in detail; [0030] FIG. 13 is a circuit diagram showing a backlight unit according to another embodiment of the present disclosure in detail; [0031] FIG. 14 is a circuit diagram showing a backlight unit according to another embodiment of to the present disclosure in detail; [0032] FIG. 15 is a circuit diagram showing a backlight unit according to another embodiment of the present disclosure in detail; [0033] FIG. 16 is a block diagram showing an LCD according to another embodiment of the present disclosure; and [0034] FIG. 17 is an exploded perspective view showing the structure of the LCD shown in FIG. 16 . DETAILED DESCRIPTION [0035] Hereinafter, embodiments in accordance with the present disclosure of disclosure will be described in more detail with reference to accompanying drawings. [0036] FIG. 1 is a circuit diagram schematically showing a backlight unit 100 according to an embodiment of the present disclosure. [0037] Referring to FIG. 1 , the backlight unit 100 includes a AC power source 101 , an isolation transformer 102 having a primary winding 102 a and a secondary winding 102 b that is DC wise isolated from the primary, an electronically controlled switch SW 1 , a plurality of capacitors (also hereafter, condensers circuit 103 ), and a plurality of cold cathode fluorescent lamps (CCFL) block 104 . The condensers circuit 103 includes a plurality of balancing capacitors (BCs) structured and arranged to uniformly distribute the high voltage AC power which has been output from the AC power source 101 and through the isolation transformer 102 to the plurality of CCFLs in the CCFL block 104 . [0038] In the backlight unit 100 , a secondary winding 102 b (at the side of the applied high voltage AC) of the isolation transformer 102 is connected to an output terminal of the AC power source 101 and is connected in series to the condensers circuit 103 and CCFL block 104 . On the other hand, a primary winding 102 a (at an isolated low voltage side of transformer 102 ) is connected to the switch SW 1 . Since the primary winding 102 a has been isolated from the secondary winding 102 b in the above structure, the switch SW 1 having a low voltage stress characteristic can be used to open or short the primary winding 102 a For this reason, because the relatively low voltage AC signal develops across the secondary 102 b in the open switch state, the switch SW 1 can be realized in a small size and of a design that does not need to feature resistance to breakdown at high voltage values such that the price and/or size of the switch can be reduced relative to switches that need to avoid breakdown at relatively higher voltage values. The isolation transformer 102 of the backlight unit 100 is a magnetic leakage type transformer in which primary and secondary windings are loosely rather than tightly magnetically coupled, and thus opening of the primary winding 102 a acts to reduce the value of the high voltage AC signal applied to the CCFL block 104 because a large AC voltage drop (corresponding to a large impedance or Hi-Z state) develops across the secondary 102 b when the primary 102 a is open. On the other hand, when the primary 102 a is shorted, a very small or essentially zero AC voltage drop develops across the secondary 102 b (corresponding to a low impedance or Low-Z state of the primary) so that driving efficiency is not impaired by the secondary 102 b being disposed in series between the AC source 101 and the load 103 / 104 . [0039] Hereinafter, the operating procedure of using the backlight unit 100 shown in FIG. 1 when the switch SW 1 opens or shorts the primary winding 102 a of the isolation transformer 102 will be briefly described with reference to FIGS. 2A , 2 B, 2 C, and 3 . [0040] FIG. 2A is an equivalent circuit diagram showing how the secondary side impedance (Z 1 ) is a function of a resonant frequency of the equivalent RLC circuit and in the case where a roughly 159 KHz AC signal is sourced in the series circuit of the secondary winding 102 b , when the primary winding 102 a of the isolation transformer 102 is left open (not short circuited), the secondary winding 102 b side has an equivalent resonant frequency at about 46 KHz and thus presents itself as a high impedance (Hi-Z) in the primary series circuit. On the other hand, in FIG. 2B , in the case where the primary winding 102 a is shorted, the equivalent RLC circuit of the secondary winding side 102 b is about 159 KHz and the secondary side winding thus presents itself as a low impedance (Low-Z) in the primary series circuit. FIG. 2C is a graph showing the impedance variation in terms of the effective resonant frequency of the equivalent RLC circuit of the secondary winding side 102 b . In other words, when the switch SW 1 is open, the resonant frequency is low but the equivalent winding inductance (WL) is high. On the other hand, when the switch SW 1 is closed, the resonant frequency is high and the equivalent winding inductance (WL) is low. Referring to FIG. 2A , when the primary winding 102 a of the isolation transformer 102 is opened, an equivalent circuit may be constructed as a RLC parallel resonant circuit. In the RLC parallel resonant circuit, a secondary-side inductance value is about 2.8 [H] (in Henrys), a secondary-side capacitance value is about 4.2 [pF] (in picoFarads), and a secondary-side resistance value is about 7.3 [kΩ] (in kilo ohms) Accordingly, a resonance frequency of about 45.7 [kHz] is calculated based on the values of the RLC equivalent circuit components. [0041] Referring to FIG. 2B , when the primary winding 102 a of the isolation transformer 102 is shorted, an equivalent circuit may be constructed as an RLC parallel resonant circuit. In the RLC parallel resonant circuit of the short circuited case, an inductance value is about 0.47 [H], a capacitance value is about 2.2 [pF], and a resistance value is about 10.2 [kΩ]. Accordingly, a resonance frequency of about 158.5 [kHz] is calculated based on the values of the RLC equivalent circuit components. [0042] In other words, when the switch SW 1 is turned “off” and thus represents an open circuit connected to the primary winding 102 a , the secondary-side equivalent circuit includes a large inductance of about 2.8 [H]. On the other hand, when the switch SW 1 is turned “on” to thus short the primary winding, a substantially smaller inductance of about 0.47 [H] appears as part of the equivalent circuit impedance of the secondary winding. Accordingly, the relation between the resonance frequency of a high frequency AC voltage applied to the CCFL block 104 through the isolation transformer 102 and the equivalent circuit impedance in the secondary winding when the primary winding is opened or shorted varies as is shown in FIG. 2C . [0043] More specifically, and as shown in FIG. 2C , when the primary winding is opened, the equivalent circuit of the secondary winding takes on a relatively low resonant frequency and a relatively large inductance (ωL). On the other hand, when the secondary winding is shorted, the equivalent circuit of the secondary winding takes on a relatively high resonant frequency and a relatively smaller inductance value, where the higher resonant frequency is much nearer to a turn-on frequency of the AC source 101 than is the low resonant frequency. Accordingly, the CCFL 104 is not turned on when the low resonant frequency, high inductance state occurs. Stated otherwise, the high frequency AC voltage of the source is applied to the CCFL block 104 only after having been reduced by a drop across the high inductance presented by the primary-side impedance of the isolation transformer 102 relative to the impedance of the CCFL block 104 . Accordingly, the high frequency AC voltage that develops across to the CCFL block 104 when the switch SW 1 is open, is less than a predetermined high voltage need to turn on the CCFL block 104 (to ignite the gases in the lamps into plasma states), and so that the CCFL block 104 is not turned on. [0044] By contrast, and as also shown in FIG. 2C , when the primary winding 102 a is shorted by a turned “on” state of the switch SW 1 , a resonance frequency of the secondary side equivalent circuit is increased, and the equivalent circuit inductance (ωL) presented by the secondary side of the transformer is decreased at the operating frequency of the CCFL 104 . Accordingly, a large AC voltage drop does not develop across the secondary winding 102 b and the CCFL block 104 is turned on. In other words, since the secondary-side impedance value is reduced in the switch SW 1 closed state, the high frequency AC voltage applied across the CCFL block 104 becomes greater than or equal to the predetermined voltage needed to initiate the turning on of the lamps in the CCFL block 104 , so that the CCFL block 104 is therefore turned on. [0045] FIG. 3A is a view showing voltage waveforms at nodes N A and N B relative to common node Nc in the case when the switch SW 1 is turned off (left open). FIG. 3B is a view showing voltage waveforms at the nodes N A and N B when the switch SW 1 is turned on (placed into a short circuiting state). As shown in FIGS. 3A and 3B , when the switch SW 1 is turned off to leave open the primary winding 102 a , the voltage value of the node N B is decreased due to the voltage drop across the secondary winding and as a result, the CCFL block 104 is not turned on. On the other hand, when the switch SW 1 is turned on to thereby provide a short circuit across the primary winding 102 a , the voltage value of node N B is increased sufficiently so that the CCFL block 104 is turned on. [0046] FIG. 4 is a table showing the relations between the variation in impedance values of the primary and secondary windings of the isolation transformer 102 and the operating state of the CCFL block 104 when the switch SW 1 is turned on or off. [0047] As described above, when the switch SW 1 is turned on or turned off, the inductance value of the secondary winding is changed from about 1.67 [H] to about 224 [mH], so that the CCFL block 104 is changed from a turn-off operation state to a turn-on operation state. The CCFL block 104 can be turned on by matching a resonance frequency of a LC series resonant circuit, which is derived from leakage inductance and capacitance of a balance condenser (BC) when the primary winding is shorted, with an inverter frequency. The CCFLs are driven through series resonance occurring by the LC series resonant circuit, so that a capacitance component and an inductance component are offset with each other in the turn-on state, and only a resistance component serves as a load, thereby reducing the value of the high AC voltage applied to the CCFL block 104 . [0048] Hereinafter, a detailed circuit diagram of a backlight unit 800 using a series of LC resonant circuits will be described with reference to FIG. 5 . [0049] Referring to FIG. 5 , the backlight unit 800 includes a first backlight section 801 , a second backlight section 802 , and a high voltage, high frequency AC power source 803 . The first and second backlight sections 801 and 802 are connected in parallel an out terminal of the AC power source 803 . [0050] The first backlight section 801 includes a first high frequency isolation transformer 811 , a first pair of MOSFETs 812 forming a first low voltage switching element, a first condensers circuit 813 , and a first CCFL block 814 . The second backlight section 802 includes a corresponding second isolation transformer 821 , a second set of MOSFETs 822 serving as a second switch element, a second condensers circuit 823 , and a second CCFL block 824 . As seen, the first and second backlight sections 801 and 802 have substantially the same circuit configuration except that each is controlled by a respective low voltage ON/OFF control signal. [0051] Each BC in the condenser circuits 813 and 823 has a capacitance value of 27 [pF], and each CCFL in the CCFL blocks 814 and 824 has a length of 52 inches. Of course, other values may be used in other variations of the basic circuit concept. The capacitance values of the BC's is a parameter that operates to determine a resonance frequency of an equivalent LC series circuit and the BC value may be set in accordance with consideration of matching impedances based on the inverter operating frequency. Thus, the capacitance values of the BC's and the lengths of the CCFL's are not limited to those disclosed for the present embodiment. [0052] The switch operation of the first FETs 812 is controlled through a first ON/OFF control signal provided from an external operation controller (e.g., a low voltage microcontroller circuit, not shown). Through the switching operation of the first FETs 812 , a primary winding of the first isolation transformer 811 is selectively shorted or opened. The switch operation of the second FETs 822 is similarly controlled through a second ON/OFF control signal provided from the external operation controller. Through the switching operation of the second FETs 822 , a primary winding of the second isolation transformer 821 is selectively shorted or opened. [0053] Hereinafter, the turn-on operation of the first backlight section 801 will be described with reference to FIGS. 6A and 6B . [0054] FIG. 6A is a table view showing the relations between the variation in inductance values of the primary and secondary windings of the first isolation transformer 811 and the corresponding operating state of the first CCFL block 814 when the first pair of MOSFETs 812 are turned off or on by application of a low voltage control signal to their isolated gate electrodes. FIG. 6B is an oscilloscope type view showing high frequency AC voltage waveforms and current waveforms that develop at and through nodes V 0 and VL of FIG. 5 relative to ground. The illustrated variation in load current ILH of the high voltage circuit is that which is applied to an input terminal of the first CCFL block 814 . On the other hand, the illustrated current ILL is that which is output from an output terminal of the first CCFL block 814 . [0055] If the first FETs 812 are turned on to thereby substantially short circuit the terminals of the primary winding of the first isolation transformer 811 , a LC series resonant circuit having leakage inductance in the primary winding of the isolation transformer 811 if formed and the capacitance of the BC performs a resonance operation for coupling the power source energy to the lamps. Through such a matched resonance operation of the LC series circuitry, the voltage VL of the load node, as shown in FIG. 6 , becomes a high frequency AC voltage that is greater than or equal to the voltage needed to initiate the turning-on of the gas lamps in the first CCFL block 814 . [0056] Referring to FIG. 5 , on the assumption that the secondary inverter frequency (f) is about 30 [kHz], a resonance frequency (f 0 ) when the primary winding is shorted is calculated from following Equation 1. [0000] fo = 1 2   π  ( L × C ) 1 2 Equation   1 [0057] In Equation 1, L refers to a secondary-side inductance value, and C refers to a secondary-side capacitance value. In this case, when the primary winding is shorted, the secondary side equivalent circuit inductance, L becomes 551 [milliH] (see FIG. 6A ), and the secondary side equivalent circuit capacitance C becomes 27 [pF]×2 (because the two BC's are basically in parallel with one another once their lamps ignite). The resonance frequency (f 0 ) of the secondary side LC series resonant circuit then becomes about 29.2 [kHz] as shown in following Equation 2 to thereby substantially match the fundamental operating frequency of the power source 803 . [0000] fo = 1 2   π  ( 551   mH × 27   pF × 2 ) 1 2  = 29.2  [ kHz ] Equation   2 [0058] In order to allow the impedance of the first CCFL block 814 , which is loaded as the LC series resonant circuit is operated at the resonance frequency (f 0 ) of about 30 kHz to appear only as resistance component (R), voltage applied to the first CCFL block 814 is obtained based on following Q factor Equation 3. [0000] Q = Z   L R = 1 ZCR = ( 2   π × f × L ) R = 1 2   π × f × C × R Equation   3 [0059] In Equation 3, ‘f’ refers to the high voltage lamps driving frequency, and ‘R’ refers to a resistance component of the CCFL block 814 . In this case, if the resistance component (R) has a value of 92 [kΩ], and the L becomes 551 [mH] (see FIG. 6A ), where the latter is the secondary-side inductance value when the primary winding is shorted, then accordingly, the AC operating voltage applied to the CCFL block 814 becomes 2.14 by the LC series resonant circuit operating at the resonance frequency (f 0 ) as shown in Equation 4. [0000] Q = ( 2   π × 30  [ kHz ] × 551  [ mH ] ( 92   k   Ω 2 )  ≈ 2.14 Equation   4 [0060] When the voltage is applied to the first CCFL block 814 by the LC series resonant circuit operating at the resonance frequency (f 0 ), the voltage V 0 at the node V 0 and the current ILH flowing through the first CCFL block 814 , which are shown in FIG. 5 , are substantially in phase as shown in FIG. 6B , and the high AC voltage applied to the first CCFL block 814 by the LC series resonant circuit can be lowered. Accordingly, the driving efficiency can be improved. Meanwhile, the second backlight section 802 has the same turn-on/turn-off operation as that of the first backlight section 801 . [0061] In addition, according to the present disclosure, time to turn on the first CCFL block 814 can be controlled through the switching operation of the switch SW 1 to open or short the primary winding of the isolation transformer 811 . Hereinafter, detailed possible structures for the switch SW 1 will be described with reference to FIGS. 7 to 9 . Meanwhile, the same reference numerals will designated to elements of FIGS. 7 to 9 identical to those of FIG. 1 . [0062] FIG. 7 is a circuit diagram showing a structure in which an AC triode switch (a TRIAC) 105 is provided as the switch SW 1 . [0063] In this case, an ON/OFF control signal can be input to a trigger terminal of the TRIAC 105 from an external control circuit to turn on/turn off the TRIAC 105 , thereby changing the turn-on/turn-off state of the CCFL block 104 . [0064] In the embodiment of FIG. 8 a photo-coupled TRIAC 106 is provided as the switch SW 1 . The photo-TRIAC 106 includes a light-sensitive TRIAC part 106 a and a light emitting diode (LED) 106 b (e.g., IR emitting diode) that is optically coupled to the TRIAC trigger layers instead of by way of direct trigger electrodes. The optical coupling of the light emitting diode 106 b to the photosensitive part 106 a is understood to be a high voltage isolation coupling. [0065] An ON/OFF signal is input to the LED 106 b from an external control circuit to turn on or off the light-sensitive TRIAC part 106 a , thereby turning on or off the photo-TRIAC 106 such that the turn-on/turn-off state of the CCFL block 104 can be changed. [0066] FIG. 9 is a circuit diagram showing a structure in which two MOSFETs 107 are connected as shown to form the switch SW 1 . Here, each of MOSFETs 107 takes half the voltage stress when the primary side is in the open circuit state. Also, the control voltage applied to the gates of the MOSFETs 107 to switch them into the conductive state can be relatively low. In this case, an ON/OFF signal can be input to gate terminals of the FETs 107 from an external control circuit to turn on or off the FETs 107 , thereby changing the turn-on/turn-off state of the CCFL block 104 . [0067] Each switching operation of the TRIAC 105 , or the photo-TRIAC 106 , or the tandem FETs 107 shown in respective FIGS. 7 to 9 and serving as the switch SW 1 is controlled by the ON/OFF control signal having a relatively low voltage and being well isolated from the high voltage side of the circuitry. In other words, in order to prevent high AC voltage from being applied to the primary winding of the isolation transformer 102 , the backlight unit 100 according to one embodiment of the present disclosure can employ a semiconductor switching device operable at low voltage as the switch SW 1 . [0068] Thus, since the backlight unit 100 can employ the semiconductor switching device operable at low voltage, the switch SW 1 can be realized in a small size, and low-voltage operation can be realized. In addition, a higher-speed switching operation can be realized as compared with a switching operation of a high voltage switch. Accordingly, the backlight unit 100 can perform a switch function (scanning control function or dynamic local dimming function for each block) at a high speed suitable for controlling the luminance of the displayed image portion of that backlighting block upon the turn-on/turn-off operation for each CCFL block. [0069] Hereinafter, a circuit configuration of a backlight unit 200 according to one embodiment of the present disclosure will be described in detail with reference to FIG. 10 . [0070] Referring to FIG. 10 , the backlight unit 200 includes an inverter circuit section 201 , a switch circuits section 202 , and a CCFL block groups section 203 . The inverter circuit section 201 includes a power transformer 211 to provide supply high frequency, high voltage AC signal to the switch circuits section 202 . The CCFL block groups section 203 includes respective CCFL blocks 203 a to 203 f . Each of the CCFL blocks 203 a to 203 f includes three CCFLs. [0071] The switch circuits section 202 includes respective isolation transformers denoted as 221 a to 221 f , corresponding switching transistors (or other switching elements) 222 a to 222 f, and condenser circuits 223 a to 223 f , which correspond to the CCFL blocks 203 a to 203 f in number, and a control circuit 224 operatively coupled to the switching elements 222 a to 222 f. [0072] Secondary windings of the isolation transformers 221 a to 221 f are connected between an output terminal of the power source transformer 211 and input terminals of the condenser circuits 223 a to 223 f , respectively, in series. First ends of primary windings of the isolation transformers 221 a to 221 f are grounded at one end, and second ends of the primary windings of the isolation transformers 221 a to 221 f are connected to the corresponding switching transistors 222 a to 222 f, respectively. A base terminal of each of the illustrated bipolar switching transistors 222 a to 222 f is connected to the control circuit 224 . (But as mentioned, other forms of switching elements may be used for items 222 a to 222 f .) The switching transistors 222 a to 222 f perform a switching operation by an ON/OFF signal input through the base terminal connected to the control circuit 224 so that the primary windings are shorted or opened. [0073] The condenser circuits 223 a to 223 f include a plurality of BCs to uniformly distribute the high frequency AC voltage signals which are output through the isolation transformers 221 a to 221 f , to the plurality of CCFLs provided in the CCFL blocks 203 a to 203 f. [0074] The control circuit 224 generates the ON/OFF signal used to time-division multiplex-wise control the turn-on/turn-off operation modes and phases of the CCFL blocks 203 a to 203 f based on a PWM (pulse width modulated) scan control signal provided from an external operation control circuit (e.g., microcontroller, not shown) for the backlight unit, and outputs the ON/OFF signal to the base terminal of each of the switching transistors 222 a to 222 f. [0075] If the respective switching transistors 222 a to 222 f are in corresponding OFF states, the respective primary windings of the isolation transformers 221 a to 221 f attain an opened circuit state. On the other hand, if the switching transistors 222 a to 222 f are in an ON state, the corresponding primary windings of the isolation transformers 221 a to 221 f become shorted. Accordingly, the control circuit 224 can time-division wise control the ON/Off states of the individual CCFL blocks 203 a to 203 f by controlling ON/OFF operation time of the switching transistors 222 a to 222 f based on the PWM scan signals applied to respective input terminals of control circuit 224 . (In an alternate embodiment, the input terminals of control circuit 224 receive digital control signals indicated duty cycles to be attained for respective ones of the individual CCFL blocks 203 a to 203 f and the control circuit 224 generates corresponding PWM control signals for application to switching elements 222 a to 222 f .) [0076] As described above, in the backlight units 100 and 200 according to one embodiment of the present disclosure, the primary windings (at the side of low-voltage) of the isolation transformers 102 and 221 a to 221 f are opened/shorted through the switching operation of the switches SW 1 and the switching transistors 222 a to 222 f, thereby allowing for duty cycle or other time-division controlling of the turn-on/turn-off operation time of the high frequency driven CCFL blocks 203 a to 203 f and thus controlling the apparent luminance of the respective CCFL blocks 203 a to 203 f . In addition, an LC series resonant circuit is constructed by leakage inductance of the isolation transformers 102 and 221 a to 221 f and capacitance of a BC, and the CCFL blocks 104 and 203 a to 203 f are turned on through the series resonance of the LC series resonant circuit. Accordingly, the value of high AC voltage applied to the CCFL blocks 104 and 203 a to 203 f can be lowered by employing only a resistance component as a load in turning on the CCFL blocks 104 and 203 a to 203 f. [0077] Accordingly, the voltage stress of a switch circuit can be reduced. In addition, the isolation transformers 102 and 221 a to 221 f , the switch SW 1 , and the switching transistors 222 a to 222 f having a low voltage stress characteristic are used, so that small-size and low-price switch circuits having low power consumption can be realized. The cost of a backlight unit employing the switch circuit can be reduced. [0078] In particular, since high AC voltage is not directly applied to the switch SW 1 and more specifically, to the collectors or drains of the switching transistors 222 a to 223 f to open or short the corresponding primary windings of the isolation transformers 221 a to 221 f , then semiconductor switching devices operating at low voltage can be used, a small-size and low-price backlight unit having low power consumption can be realized. [0079] Although the switching transformers 222 a to 222 f are used in the switching circuit 202 shown in FIG. 10 , a semiconductor switching device such as the TRIAC 105 , the photo-TRIAC 106 , or the MOSFETs 107 can be used instead of the bipolar switching transistors 222 a to 222 f as shown in FIGS. 7 to 9 . If the semiconductor switching device is employed when the backlight unit 200 according to one embodiment of the present disclosure is adapted to the LCD which will be described later, a function (scanning control function or dynamic local dimming function for each block) to switch the turn-on/turn-off state of CCFL blocks at a high speed in a block unit can be performed to represent the maximum brightness of a displayed image area according to the brightness of an input image for that area. Accordingly, the image quality and/or power consumption efficiency of the LCD can be improved. [0080] FIG. 11 is a circuit diagram showing a backlight unit 300 according to another embodiment of the present disclosure. [0081] Referring to FIG. 11 , the backlight unit 300 includes an inverter circuit section 301 , a switch circuits section 302 , and a CCFL blocks group 303 . The CCFL blocks group 303 includes CCFL blocks 331 a to 331 f . Each of the CCFL blocks 331 a to 331 f includes three CCFLs. A first phase or “normal”-phase high frequency high voltage AC signal is applied to the odd numbered CCFL blocks 331 a to 331 c (normal-phase CCFL blocks), and a differently phased, for example inverse-phase high frequency, high voltage AC signal is applied to the interdigitated and even numbered CCFL blocks 331 d to 331 f (inverse-phase CCFL blocks). [0082] The inverter circuit section 301 includes a normal-phase power outputting transformer 311 and an inverse-phase power outputting transformer 312 . The normal-phase power transformer 311 supplies the normal-phase high AC voltage signal to the odd-number wise ordered parts of the switch circuit 302 , and the inverse-phase power transformer 312 supplies the inverse-phase high AC voltage signal to the even-number number wise ordered parts of the switch circuit 302 . [0083] The switch circuits section 302 thus includes normal-phase isolation transformers 321 a to 321 c , inverse-phase isolation transformers 321 d to 321 f , normal-phase switching transistors 322 a to 322 c , inverse-phase switching transistors 322 d to 322 f, condenser circuits 323 a to 323 f , and a control circuit 324 . [0084] Secondary windings of the normal-phase isolation transformers 321 a to 321 c are connected between an output terminal of the normal-phase power transformer 311 and input terminals of the condenser circuits 323 a to 323 c , respectively, in series. First ends of primary windings of the normal-phase isolation transformers 321 a to 321 c are grounded, and second ends of the primary windings are connected to the normal-phase switching transistors 322 a to 322 c , respectively. [0085] Secondary windings of the inverse-phase isolation transformers 321 d to 321 f are connected between an output terminal of the inverse-phase power transformer 312 and input terminals of the condenser circuits 323 d to 323 f , respectively, in series. First ends of primary windings of the inverse-phase isolation transformers 321 d to 321 f are grounded, and second ends of the primary windings are connected to the inverse-phase switching transistors 322 d to 322 f, respectively. [0086] A base terminal of each of the normal-phase switching transistors 322 a to 322 c is connected to the control circuit 324 . The normal-phase switching transistors 322 a to 322 c receive an ON/OFF signal for a normal-phase operation from the control circuit 324 through the base terminals (or alternatively gate electrodes) to perform the desired switching operations at appropriate time points, thereby shorting or opening the primary windings of the normal-phase isolation transformers 321 a to 321 c. [0087] A base terminal of each of the inverse-phase switching transistors 322 d to 322 f is connected to the control circuit 324 . The inverse-phase switching transistors 322 d to 322 f receive an ON/OFF signal for an inverse-phase operation from the control circuit 324 through the base terminal to perform a switching operation, thereby shorting or opening the primary windings of the inverse-phase isolation transformers 321 d to 321 f. [0088] The condenser circuits 323 a to 323 f include a plurality of BCs to uniformly distribute normal-phase high AC voltage, which is output from the normal-phase isolation transformers 321 a to 321 c , and inverse-phase high AC voltage, which is output from the inverse-phase isolation transformers 321 d to 321 f , to a plurality of CCFLs in the CCFL blocks 331 a to 331 f. [0089] The control circuit 324 generates the ON/OFF signal used to time-division wise control the duty cycles and the turn on and off times the CCFL blocks 331 a to 331 f based on a PWM scan signal provided from an external operation control circuit (not shown) for a backlight unit, and outputs the ON/OFF signal to the base terminal, and outputs the ON/OFF signal to the base terminals of the normal-phase switching transistors 322 a to 322 c and the inverse-phase switching transistors 322 d to 322 f. [0090] When the normal-phase switching transistors 322 a to 322 c are in an off state, the primary windings of the normal-phase isolation transformers 321 a to 321 c are opened. When the normal-phase switching transistors 322 a to 322 c are in an on state, the primary windings of the normal-phase isolation transformers 321 a to 321 c are shorted. Accordingly, the control circuit 324 controls an on/off operation time of the normal-phase switching transistors 322 a to 322 c based on the PWM scan signal to time-division control the turn-on/turn-off operation time of the CCFL blocks 331 a to 331 c. [0091] When the inverse-phase switching transistors 322 d to 322 f are in the off state, the primary windings of the inverse-phase isolation transformers 321 d to 321 f are opened. When the inverse-phase switching transistors 322 d to 322 f are in the on state, the primary windings of the inverse-phase isolation transformers 321 d to 321 f are shorted. Accordingly, the control circuit 324 controls an on/off operation time of the inverse-phase switching transistors 322 d to 322 f based on the PWM scan signal to time-division control the turn-on/turn-off operation time of the CCFL blocks 331 d to 331 f. [0092] Since the CCFL blocks 331 a to 331 c to receive normal-phase high AC voltage are alternately interposed with the CCFL blocks 331 d to 331 f to receive inverse-phase high AC voltage in the backlight unit 300 shown in FIG. 11 , noise components between adjacent CCFL blocks can be offset with each other because one lamp will be receiving a positive going noise spike, if so present in the high voltage power signal and the next adjacent lamp will be receiving a negative going noise spike, if so present. Accordingly, the quality of a display image can be improved by employing out of phase lamp drive signals. [0093] Since the primary side switches are in the low voltage portions of the isolation transformers, accordingly, in the backlight unit 300 shown in FIG. 11 , the voltage stress of each switch circuit can be reduced, and the normal-phase isolation transformers 321 a to 321 c , the inverse-phase isolation transformers 321 d to 321 f , the normal-phase switching transistors 322 a to 322 c , and the inverse-phase switching transistors 322 d to 322 f having a low voltage stress characteristic can be used, so that small-size and low-price switch circuits having low power consumption can be realized. Accordingly, the power consumption, size, and price of a backlight unit employing the switch circuits can be also reduced. [0094] FIG. 12 is a circuit diagram showing a backlight unit 400 in which CCFLs of receiving normal-phase high AC voltage are alternately aligned with CCFLs of receiving inverse-phase high AC voltage. Moreover, the balancing condensers (BC's) in each lamp block are alternatively connected as shown. [0095] Referring to FIG. 12 , the backlight unit 400 includes an inverter circuit 401 , a switch circuit 402 , and a CCFL block group 403 . The CCFL block group 403 includes CCFL blocks 431 a to 431 f. Each of the CCFL blocks 431 a to 431 includes four CCFLs. In each of the CCFL blocks 431 a to 431 f , half the CCFLs are connected to receive the normal-phase high AC voltage signal and the other half are connected to alternately receive the out of phase (e.g., inverse phase) high AC voltage signal. [0096] The high voltage lamps driving circuit 401 includes a normal-phase power transformer 411 and an inverse-phase power transformer 412 . The normal-phase power transformer 411 supplies normal-phase high AC voltage signal to the switch circuit 402 . [0097] The inverse-phase power transformer 412 supplies differently phased (e.g., inverse-phase) high AC voltage signal to the switch circuit 402 . [0098] The switch circuit 402 includes normal-phase isolation transformers 421 a to 421 f , inverse-phase isolation transformers 423 a to 423 f , normal-phase switching transistors 422 a to 422 f, inverse-phase switching transistors 424 a to 424 f , condenser circuits 425 a to 425 f , and a control circuit 426 . [0099] Secondary windings of the normal-phase isolation transformers 421 a to 421 f are connected between an output terminal of the normal-phase power transformer 411 and input terminals of the condenser circuits 425 a to 425 f , respectively, in series. First ends of primary windings of the normal-phase isolation transformers 421 a to 421 f are grounded, and second ends of the primary windings are connected to the normal-phase switching transistors 422 a to 422 f, respectively. [0100] Secondary windings of the inverse-phase isolation transformers 423 a to 423 f are connected between an output terminal of the inverse-phase power transformer 412 and the input terminals of the condenser circuits 425 a to 425 f , respectively, in series. First ends of primary windings of the inverse-phase isolation transformers 423 a to 423 f are grounded, and second ends of the primary windings are connected to the inverse-phase switching transistors 424 a to 424 f , respectively. [0101] A base terminal of each of the normal-phase switching transistors 422 a to 422 f is connected to the control circuit 426 . The normal-phase switching transistors 422 a to 422 f receive an ON/OFF signal for a normal-phase operation from the control circuit 426 through the base terminal to perform a switching operation, thereby shorting or opening the primary windings of the normal-phase isolation transformers 421 a to 421 f. [0102] A base terminal of each of the inverse-phase switching transistors 424 a to 424 f is connected to the control circuit 426 . The inverse-phase switching transistors 424 a to 424 f receive an ON/OFF signal for an inverse-phase operation from the control circuit 426 through the base terminal and perform a switching operation in response to the ON/OFF signal to short or open the primary windings of the inverse-phase isolation transformers 423 a to 423 f. [0103] The condenser circuits 425 a to 425 f include a plurality of BCs to uniformly distribute normal-phase high AC voltage signal, which is output from the normal-phase isolation transformers 421 a to 421 f , or the inverse-phase high AC voltage signal, which is output from the inverse-phase isolation transformers 423 a to 423 f , to a plurality of CCFLs in the CCFL blocks 431 a to 431 f. [0104] The control circuit 426 generates the ON/OFF signal used to time-division control time to turn on the CCFL blocks 431 a to 431 f based on a PWM scan signal provided from an external operation control circuit (not shown) for a backlight unit, and outputs the ON/OFF signal to the base terminals of the normal-phase switching transistors 422 a to 422 f and the inverse-phase switching transistors 424 a to 424 f. [0105] When the normal-phase switching transistors 422 a to 422 f are in an off state, the primary windings of the normal-phase isolation transformers 421 a to 421 f are opened. When the normal-phase switching transistors 422 a to 422 f are in an on state, the primary windings of the normal-phase isolation transformers 421 a to 421 f are shorted. Accordingly, the control circuit 426 controls an on/off operation time of the normal-phase switching transistors 421 a to 421 f based on the PWM scan signal to time-division control the turn-on/turn-off time of the CCFLs that receive the normal-phase high AC voltage signal and are provided in the CCFL blocks 431 a to 431 f. [0106] When the inverse-phase switching transistors 424 a to 424 f are in the off state, the primary windings of the inverse-phase isolation transformers 423 a to 423 f are opened. When the inverse-phase switching transistors 424 a to 424 f are in the on state, the primary windings of the inverse-phase isolation transformers 423 a to 423 f are shorted. Accordingly, the control circuit 426 controls an on/off operation time of the inverse-phase switching transistors 424 a to 424 f based on the PWM scan signal to time-division control the turn-on/turn-off operation time of the CCFLs that receive the inverse-phase high AC voltage signal and are provided in the CCFL blocks 431 a to 431 f [0107] Since the backlight unit 400 shown in FIG. 12 has a circuit configuration in which an even number of (e.g., four) CCFLs are provided in each of the CCFL blocks 431 a to 431 f and these are alternatively connected to alternately receive the normal-phase high AC voltage signal and the differently phased (e.g., inverse-phase) high AC voltage signal, noise components between adjacent CCFL blocks may be offset with each other. Accordingly, the quality of a display image can be improved. [0108] Accordingly, in the backlight unit 400 shown in FIG. 12 , the voltage stress of a switch circuit can be reduced, and the normal-phase isolation transformers 421 a to 421 f , the inverse-phase isolation transformers 423 a to 423 f , the normal-phase switching transistors 422 a to 422 f, and the inverse-phase switching transistors 424 a to 424 f having a low voltage stress characteristic can be used, so that small-size and low-price switch circuits having low power consumption can be realized. Accordingly, the power consumption, size, and price of a backlight unit employing the switch circuits can be also reduced. [0109] Although the switch circuits 302 and 402 shown in FIGS. 11 and 12 employ the switching transistors 322 a to 322 f, 422 a to 422 f, and 424 a to 424 f , semiconductor switching devices such as the TRIAC 105 , the photo-sensitive TRIAC 106 , and the MOSFET 107 shown in FIGS. 7 to 9 can be used. If backlight units 300 and 400 employing the semiconductor switching device are adapted to the LCD, the turn-on/turn-off state of CCFL blocks can be switched at a high speed in a block unit suitably for the brightness of an input image, thereby improving image quality. [0110] FIG. 13 is a circuit diagram showing a backlight unit 500 according to another embodiment of the present disclosure. [0111] Referring to FIG. 13 , the backlight unit 500 includes an inverter circuit 501 , a switch circuit 502 , and a CCFL block group 503 . [0112] The inverter circuit 501 includes an AC power source 511 to provide supply voltage to the switch circuit 502 . The CCFL block group 503 includes CCFL blocks 531 a to 531 f . Each of the CCFL blocks 531 a to 531 f may include an even number of CCFL's (e.g., two CCFLs). [0113] The switch circuit 502 includes isolation transformers 521 a to 521 f , semiconductor switch circuits 522 a to 522 f, and condenser circuits 523 a to 523 f that correspond to the CCFL blocks 531 a to 531 f in number. [0114] A secondary winding of each of the isolation transformers 521 a to 521 f is connected between an output terminal of the AC power source 511 and an input terminal of each of the condenser circuits 523 a to 523 f , in series. Both ends of a primary winding of each of the isolation transformers 521 a to 521 f are connected to each of the semiconductor switch circuits 522 a to 522 f. Each of the semiconductor switch circuits 522 a to 522 f includes two MOSFETs and two kickback current routing diodes, and base terminals of the two MOSFETs are connected to an input line 524 for a block control signal. The semiconductor switch circuits 522 a to 522 f are provided with the input line 524 connected to an external control circuit (not shown). Each of the semiconductor switch circuits 522 a to 522 f receives a control signal (ON/OFF signal) for each block from the input line 524 through the base terminal to perform a switching operation, so that the primary winding is shorted or opened. [0115] The condenser circuits 523 a to 523 f include a plurality of BCs to uniformly distribute high AC voltage, which is output from the isolation transformers 521 a to 521 f , to a plurality of CCFLs provided in the CCFL blocks 531 a to 531 f. [0116] When the semiconductor switch circuits 522 a to 522 f are in an off state, primary windings of the isolation transformers 521 a to 521 f are opened. When the semiconductor switch circuits 522 a to 522 f are in an on state, the primary windings of the isolation transformers 521 a to 521 f are shorted. The on/off operation time of the semiconductor switch circuits 522 a to 522 f is controlled based on the control signal (ON/OFF signal) for each block, thereby time-division control the turn-on/turn-off operation time of the CCFL blocks 531 a to 531 f. [0117] Accordingly, the voltage stress of a switch circuit can be reduced, and the isolation transformers 521 a to 521 f and the semiconductor switch circuits 522 a to 522 f having a low voltage stress characteristic can be used. Accordingly, the cost of a backlight unit employing the switch circuit can be reduced. In particular, high AC voltage, which is applied to CCFL blocks, is not applied to the semiconductor switch circuits 522 a to 521 f to switch the open/short state of the primary windings of the isolation transformers 521 a to 521 f . Accordingly, since the semiconductor switching device to operate at low voltage can be used, a small-size and low-price backlight unit having low power consumption can be realized. [0118] Meanwhile, although MOSFETs are used in the semiconductor switch circuits 522 a to 522 f of the switch circuit 502 shown in FIG. 13 , semiconductor switching devices such as the TRIAC 105 or the photo-TRIAC 106 may be used as shown in FIGS. 7 and 8 . Such a semiconductor switching device is employed, so that a switching operation (scanning control function or local dimming for each block) to switch the turn-on/turn-off operation state of CCFL blocks at a high speed in a block unit suitably for the brightness of an input image can be adapted to an LCD which will be described later. Accordingly, the image quality can be improved. [0119] FIG. 14 is a circuit diagram showing a backlight unit 600 according to another embodiment of to the present disclosure. The present embodiment is characterized in that a balance coil is used instead of a condenser circuit including a BC. [0120] Referring to FIG. 14 , the backlight unit 600 includes an inverter circuit 601 , a switch circuit 602 , and a CCFL block group 603 . [0121] The inverter circuit 601 includes an AC power source 611 to provide supply voltage to the switch circuit 602 . The CCFL block group 603 includes CCFL blocks 631 a to 631 f. Each of the CCFL blocks 631 to 631 f includes two CCFLs. [0122] The switch circuit 602 includes isolation transformers 621 a to 621 f and semiconductor switch circuits 622 a to 622 f which correspond to the CCFL blocks 631 a to 631 f in number. [0123] A secondary winding of each of the isolation transformers 621 a to 621 f is divided (e.g., center tapped) in each CCFL provided in the CCFL blocks 631 a to 631 f to thereby construct a balanced coil. The central tap point of the secondary winding of each of the isolation transformers 621 a to 621 f is connected to an output terminal of the AC power source 611 , and the opposed non-center ends of the secondary windings are connected to a respective one or more CCFLs. In addition, both ends of a primary winding of each of the isolation transformers 621 a to 621 f are connected to each of the semiconductor switch circuits 622 a to 622 f. Each of the semiconductor circuits 622 a to 622 f includes two FETs and two diodes, and base terminals of the two FETs are connected to an input line 624 through which a control signal for each block is input. The semiconductor switch circuits 622 a to 622 f receive a control signal (ON/OFF signal) for each block through the base terminal connected to the input line 624 to perform a switching operation so that the primary winding is shorted or opened. [0124] When the semiconductor switch circuits 622 a to 622 f are in an off state, the primary windings of the isolation transformers 621 a to 621 f are opened. When the semiconductor switch circuits 622 a to 622 f are in an on state, the primary windings of the isolation transformers 621 a to 621 f are shorted. The on/off operation time of the semiconductor switch circuits 622 a to 622 f is controlled based on the control signal(ON/OFF signal) for each block, so that the turn-on/turn-off operation time of the CCFL blocks 631 a to 631 f can be time-division controlled. [0125] Accordingly, the voltage stress of the switch circuit can be improved, and isolation transformers 621 a to 621 f and the semiconductor switch circuits 622 a to 622 f having a low voltage stress characteristic can be used, so that a small-size and low-price switch circuit having low power consumption can be realized. Accordingly, the power consumption, size, and price of a backlight unit employing the switch circuit can be also reduced. In particular, since high AC voltage, which is applied to CCFL blocks, is not applied to the semiconductor switch circuits 622 a to 622 f to switch the open/short state of the primary winding of the isolation transformers 621 a to 621 f , a semiconductor switching device operating at low voltage can be used, thereby contributing to the reduction of the power consumption, size, and price of the backlight unit. Further, the secondary winding of the isolation transformers 621 a to 621 f is divided to construct a balanced coil structure, so that a distribution-balancing condenser can be omitted, and the price of the inverter driving circuit can be more reduced. Since the resonance frequency is adjusted by using only an inductance component and without concern for the capacitance of balancing condensers (not present), impedance matching with CCFLs can be more easily adjusted so that the turn-on/turn-off operation can be easily controlled. [0126] Although FETs are used in the switching transformers 622 a to 622 f of the switching circuit 602 a shown in FIG. 14 , a semiconductor switching device such as the TRIAC 105 , or the photo-TRIAC 106 can be used as shown in FIGS. 7 to 9 . Such a semiconductor switching device is employed, so that a switching operation (scanning control function or local dimming for each block) to switch the turn-on/turn-off operation state of CCFL blocks at a high speed in a block unit suitably for the brightness of an input image can be adapted to an LCD which will be described later. Accordingly, the image quality can be improved. [0127] FIG. 15 is a circuit diagram showing a backlight unit 700 according to another embodiment of the present disclosure. The illustrated embodiment is again characterized in that a balance coil structure is used instead of a condenser circuit including a BC. Moreover, independent and optionally differently phased signal sources 711 , 712 are used to power each CCFL block (e.g., 731 a ). [0128] Referring to FIG. 15 , the backlight unit 700 includes an inverter circuit 701 , a switch circuit 702 , and a CCFL block group 703 . [0129] The high voltage lamps driving circuit 701 includes a normal-phase AC power source 711 and a differently phased (e.g., inverse-phased) power source 712 , and normal-phase supply voltage and inverse-phase supply voltage signals are supplied to the switch circuit 702 . The CCFL block group 703 includes CCFL blocks 731 a to 731 f . Each of the CCFL blocks 731 a to 731 f includes an even number (e.g., two) of CCFLs. [0130] The switch circuit 702 includes isolation transformers 721 a to 721 f and semiconductor switch circuits 722 a to 722 f that correspond to the CCFL blocks 731 a to 731 f in number. [0131] A secondary windings of the isolation transformers 721 a to 721 f are each divided in each CCFL block among CCFL blocks 731 a to 731 f to thereby construct a balanced coil structure. Inner ends of the divided secondary winding of each of the isolation transformers 721 a to 721 f are connected to output terminals of the normal-phase power source 711 and the inverse-phase power source 712 , respectively. Outer ends of the secondary winding of each of the isolation transformers 721 a to 721 f are connected to the CCFLs. Both ends of a primary winding are connected to each of the semiconductor switch circuits 722 a to 722 f. Each of the semiconductor switch circuits 722 a to 722 f includes two FETs and two diodes, and base terminals of two FETs are connected to an input line 724 through which a control signal for each block is input. The semiconductor switch circuits 722 a to 722 f receive a control signal (ON/OFF signal) for each block through the base terminals connected to the input line 724 to perform a switching operation to short or open the primary windings. [0132] When the semiconductor switch circuits 722 a to 722 f are in an off state, the primary windings of the isolation transformers 721 a to 721 f are opened. When the semiconductor switch circuits 722 a to 722 f are in an on state, the primary windings of the isolation transformers 721 a to 721 f are shorted. Accordingly, an on/off operation time of the semiconductor switch circuit 722 a to 722 f is controlled based on the control signal (ON/OFF signal) for each block, so that the turn-on/turn-off operation time of each of the CCFL blocks 731 a to 731 f can be time-division controlled. [0133] Accordingly, the voltage stress of the switch circuit can be reduced, and isolation transformers 721 a to 721 f and the semiconductor switch circuits 722 a to 722 f having a low voltage stress characteristic can be used, so that a small-size and low-price switch circuit having low power consumption can be realized. Accordingly, the power consumption, size, and price of a backlight circuit employing the above switch circuit can be also reduced. In particular, since high AC voltage, which is applied to CCFL blocks, is not applied to the semiconductor switch circuits 722 a to 722 f to switch the open/short state of the primary windings of the isolation transformers 721 a to 721 f , a semiconductor switching device operating at low voltage can be used, thereby contributing to the reduction of the power consumption, size, and price of the backlight unit. Further, the secondary winding of the isolation transformers 721 a to 721 f is divided to construct a balance coil, so that a corresponding balance condenser (BC) can be omitted. Accordingly, the price of the inverter circuit can be more reduced. Since the resonance frequency is adjusted by using only an inductance component, impedance matching with CCFLs can be easily adjusted so that the turn-on/turn-off operation can be easily controlled. [0134] In the inverter circuit 702 shown in FIG. 15 , although MOSFETs are used in the semiconductor switch circuits 722 a to 722 f, a semiconductor switching device such as the TRIAC 105 or the photo-TRIAC 106 can be used as shown in FIGS. 7 to 9 . Such a semiconductor switching device is employed, so that a switching operation (scanning control function or local dimming for each block) to switch the turn-on/turn-off operation state of CCFL blocks at a high speed in a block unit suitably for the brightness of an input image can be adapted to an LCD. Accordingly, the image quality can be improved. [0135] The secondary winding of the isolation transformers 621 a to 621 f is evenly divided to construct a balance coil as shown in FIG. 14 , so that a JIN type transformer normally used as a conventional balance coil can be removed. Accordingly, an isolation transformer performing both functions of an inverter transformer and a balance coil is used, thereby more reducing the size and the price of the inverter circuit. [0136] FIG. 16 is a block diagram showing an LCD 900 including a backlight unit 930 having the structure similar to that of the backlight unit 200 shown in FIG. 10 . [0137] As shown in FIG. 16 , the LCD 900 includes an AC/DC power supply 910 , an LCD module 920 , and the backlight unit 930 [0138] The AC/DC power supply 910 includes an AC power plug 911 , an AC/DC rectifier 912 , and a first DC-to-DC converter 913 . The AC/DC power supply 910 converts external commercial AC supply voltage ( 100 V or 240 V) into DC supply voltage and outputs the DC supply voltage to the LCD module 920 by way of the first DC-to-DC converter 913 . [0139] The LCD module 920 includes a second DC/DC converter 921 , a common electrode (Vcom) voltage generator 922 , a gamma (γ) voltage generator 923 , an LCD panel 924 , and the backlight unit 930 to display images corresponding to image data provided from an external graphic controller (not shown). The LCD panel 924 includes a plurality of liquid crystal devices connected to each other at a region in which a plurality of data lines and a plurality of gate lines extending from data and gate drivers, respectively, cross each other. The liquid crystal devices are distributed in a plurality of display regions to control the gray scale of each display region. [0140] The Vcom generator 922 generates common electrode voltage Vcom based on level-converted DC voltage supplied from the second DC/DC converter 921 and outputs the common electrode voltage Vcom to the LCD panel 924 . The γ voltage generator 923 generates γ voltage Vdd based on the level-converted DC voltage in the DC/DC converter 921 to supply the γ voltage to the LCD panel 924 . Although, the Vcom generator 922 and the γ voltage generator 923 are separated from the LCD panel 924 as shown in FIG. 16 , the Vcom generator 922 and the γ voltage generator 923 may be embedded in the LCD panel 924 . [0141] The backlight unit 930 includes an inverter section 931 and a backlight section 932 . The inverter section 931 includes the isolation transformers 221 a to 221 f , the switching transistors 222 a to 222 f, and the optional condenser circuits 223 a to 223 f provided in the switch circuit 202 such as shown in FIG. 10 . The backlight section 932 includes the CCFL block group 203 shown in FIG. 10 . A plurality of CCFL blocks in the CCFL block group 203 correspond to the plural display regions, respectively. The turn-on/turn-off operation time of the CCFL blocks is time-division controlled corresponding to the brightness of each display region when an input image is displayed on the LCD panel 924 . [0142] Since the inverter section 931 provided in the backlight unit 930 of the LCD 900 includes the isolation transformers 221 a to 221 f , the switching transistors 222 a to 222 f, and the condenser circuits 223 a to 223 f , the voltage stress of the switch circuit can be reduced, and the isolation transformers 221 a to 221 f and the switching transistors 222 a to 222 f having a low voltage stress characteristic can be used. Therefore, a small-size and low-price switch circuit having low power consumption can be realized. As a result, the power consumption and cost of a backlight circuit employing the above switch circuit can be also reduced. In addition, a switching function (scanning control function or local dimming function for each block) to switch the turn-on/turn-off operation state of the CCFL blocks at a high speed can be used to control the brightness of a display image according to the brightness of an input image, so that the image quality of the LCD 900 can be improved. Meanwhile, the AC/DC power supply 910 may be embedded in the LCD module 920 . [0143] FIG. 17 is an exploded perspective view showing an assembly of LCD 1000 having the structure similar to that of the LCD 900 shown in FIG. 16 . [0144] As shown in FIG. 17 , the LCD 1000 includes a backlight assembly 1010 , a display unit 1070 , and a container 1080 . [0145] The display unit 1070 includes a liquid crystal display panel 1071 to display an image and a data printed circuit 1072 and a gate printed circuit 1073 to output a driving signal used to drive the liquid crystal display panel 1071 . The data and gate printed circuits 1072 and 1073 are electrically connected with the liquid crystal display panel 1071 through a data tape carrier package (TCP) 1074 and a gate TCP 1075 . [0146] The liquid crystal display panel 1071 includes a first substrate 1076 , a second substrate 1077 opposite to the first substrate 1076 , and a liquid crystal 1078 interposed between the first and second substrates 1076 and 1077 . [0147] The first substrate 1076 may be a transparent glass substrate in which TFTs (not shown) serving as a switching device are provided in the form of a matrix. Data and gate lines are connected to source and gate terminals of each TFT, and a transparent electrode (not shown) including transparent conductive material is formed at a drain terminal [0148] The second substrate 1077 may be a substrate in which RGB pixels (not shown) are formed through a thin film process. The second substrate 1077 is provided thereon with a common electrode (not shown) including transparent conductive material. [0149] The container 1080 includes a bottom surface 1081 and a sidewall 1082 formed along the edge of the bottom surface 1081 to form a receiving space. The container 1080 fixes the backlight assembly 1010 and the liquid crystal display panel 1071 to prevent the backlight assembly 1010 and the liquid crystal display panel 1071 from moving. [0150] The bottom surface 1081 has an area sufficient to receive the backlight assembly 1010 and has configuration corresponding to that of the backlight assembly 1010 . According to the present embodiment, the bottom surface 1081 and the backlight assembly 1010 have a rectangular plate shape. The sidewall 1082 approximately perpendicularly extends from the edge of the bottom surface 1081 such that the backlight assembly 1010 does not deviate out of the container 1080 . [0151] According to the present embodiment, the LCD 1000 further includes an inverter circuit 1060 and a top chassis 1090 . [0152] The inverter circuit 1060 is disposed outside of the container 1080 to generate high voltage discharge signals used to drive the lamps of the backlight assembly 1010 . The discharge voltage generated from the inverter circuit 1060 is applied to the backlight assembly 1010 through first and second power lines 1063 and 1064 . The first and second power lines 1063 and 1064 may be connected with first and second electrodes 1040 a and 1040 b , which are formed at both side portions of the backlight assembly 1010 , directly or by using another part (not shown). In addition, the switch circuit 202 including the isolation transformers 221 a to 221 f , the switching transistors 222 a to 222 f, and the condenser circuits 223 a to 223 f may be embedded in the inverter circuit 1060 . [0153] The top chassis 1090 is coupled with the container 1080 while surrounding the edge of the liquid crystal display panel 1071 . The top chassis 1090 can protect the liquid crystal display panel 1071 from external shock, and prevent the liquid crystal display panel 1071 from deviating from the container 1080 . [0154] The LCD 1000 may further include at least one optical sheet 1095 to improve the characteristic of light output from the backlight assembly 1010 . The optical sheet 1095 may include a diffusion sheet to diffuse light or a prism sheet to concentrate light. [0155] Accordingly, when the inverter circuit 1060 , which performs a scanning control function for the turning-on operation of a CCFLA block group or a control function for the turn-on/turn-off operation time of each CCFL block by shorting or opening the primary windings of the isolation transformers through the ON/OFF operation of switching transistors, is adapted for an LCD including a power supplying inverter, the voltage stress of the inverter circuit 1060 can be reduced, and the low power consumption, small-size, and low price of the inverter circuit 1060 can be realized. In addition, the above-described backlight unit 100 , 200 , or 300 is adapted to the LCD 1000 , so that a switching function (scanning control function or local dimming function for each block) to switch the turn-on/turn-off operation state of the CCFL blocks at a high speed in a block unit can be performed in order to control the brightness of a display image according to the brightness of an input image. Accordingly, image quality can be improved. [0156] According to the embodiments of the present disclosure, although the inverter circuit is separated from the switch circuit, the inverter circuit may alternatively be integrated with the switch circuit. [0157] Although exemplary embodiments of the present disclosure have been described, it is understood that the present teachings should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art in view of the foregoing and within the spirit and scope of the present teachings.	A lamp driving circuit is provided for controlling individual block luminances provided by corresponding locally dimmed blocks of a backlight unit of an LCD system where the backlight unit employs high voltage discharge lamps that each need to have an AC excitation signal of at least predetermined minimum high voltage level developed there across in order to generate light. The lamp driving circuit includes a plurality of isolation transformers and corresponding low voltage switch circuits. Each isolation transformer has primary windings and a secondary winding. The secondary winding is interposed between a high voltage AC power source and a corresponding one or more lamps. The equivalent circuit impedance of the secondary winding determines what voltage will develop across its respective lamps. The low voltage switch circuits are operative to alter the equivalent circuit impedances of their respective primary windings, which impedance changes are then reflected by mutual inductance coupling into the secondary windings. Thus control circuits operating at relatively low voltages can be used to control the ON/OFF states of the lamps.	6
[0001] This application claims benefit under 35 U.S.C. 119(e) to Provisional Application No. 60/746,702 filed May 8, 2007. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to a device and the method of using it for the evacuation of papules, pustules, vesicles; dermatological afflictions commonly referred to as pimples, zits, blackheads, whiteheads; as well as to other similar dermatological conditions that result in a collection of puss, blood, other fluid, bacteria, dirt, dead cells or dried or solid matter underneath the skin. [0004] 2. Description of Related Art [0005] The underlying causes of these dermatological conditions are hard to treat and difficult to prevent. The visible, palpable manifestation of pimples, blackheads and other unsightly skin blemishes are often a source of personal discomfiture and even embarrassment. Accordingly, a person so afflicted often may attempt removal of the outward, visible manifestation by expelling their contents and reducing, at least temporarily, the associated swelling, even at the risk of pain and further infection. [0006] While this invention relates to the evacuation and removal of many different forms of matter beneath the skin and other dermatological manifestations, as set forth above, merely for the sake of brevity and convenience, the description that follows will describe the evacuation and removal of pimples and blackheads. [0007] A common, simple method of removing a pimple involves squeezing using fingers or even fingernails, until the pimple pops and the contents can be expelled. The pimple may also be evacuated by squeezing the pimple using some other readily available device, such as tweezers. Another common method involves lancing the pimple to facilitate the expulsion of the internal contents, often performed in combination with some subsequent squeezing to fully expel the contents. [0008] There are many problems associated with squeezing a pimple between fingers and/or fingernails to forcibly expel its contents. For example, fingers are large in comparison to the area of the pimple so that visibility of the target may be impaired by the size and shape of the fingers. Squeezing in this manner becomes a clumsy, painfully inexact process. Sometimes the edges of fingernails are used for more precision and improved visibility, but fingernails are sharp and dirty and may cause lacerations and secondary infections. While the use of tweezers may avoid some of the above-mentioned disadvantages, tweezers have sharp edges, ridges and flat, longitudinal pressure surfaces which are not well suited to compressing pimples and the like. In this respect, tweezers and fingers cannot apply their squeezing force uniformly around the circumference of the pimple. Worse still, the flat gripping surface of the tweezers' face tends to pull the skin on and around the pimple, causing the already-taught, swollen skin to tear or to be cut by the tweezers' edge. SUMMARY OF THE INVENTION [0009] The present invention provides a device and method for the removal of matter beneath the skin comprising: [0010] A squeezing interface adapted to provide a more uniform squeezing force around the circumference of the pimple; [0011] A squeezing interface which is adapted to slide across the surface of the skin while applying squeezing forces inwardly and, optionally, upwardly around the circumference of the pimple, reducing cutting and pulling forces on the skin; [0012] A more easily and uniformly directable squeezing force to expel the contents of the pimple, preferably up and out of the top of the pimple head; [0013] A device which is adapted to fit easily and securely between two fingers and which provides the user with greater control and precision in applying the necessary squeezing force; and [0014] A device which provides a visually unobstructed squeezing interface. [0015] The squeezing interface of the present invention comprises two or more opposing squeezing members comprising concave or convex (curved) squeezing faces between which the pimple may be placed. When the squeezing members are deployed by the user, the squeezing faces are brought together toward a central axis to contact the pimple and apply pressure at approximately symmetrical areas around the circumference of the pimple. [0016] When the device's squeezing members are deployed into a closed or partially closed position, the opposing squeezing faces comprise partial or contiguous boundaries of an approximately round or elliptical lumen. The shape and the size of the lumen may be varied across devices of the present invention so that the user may select a preferred device according to the size and shape of the pimple to be treated. Any single device may treat a range of pimple sizes as the squeezing faces may contact the walls of the pimple through a range of deployed positions, before the squeezing members are fully deployed. [0017] Optionally, the opposing squeezing faces may be angled, concentrically, from a lower, inward portion of the lumen, to an upper, outward portion of the lumen to provide an inward and upward vector of force as the squeezing faces come together, providing a scooping effect. [0018] With the squeezing members in a fully open position, the device is placed against the surface of the skin with the squeezing faces loosely surrounding the target pimple. As the user deploys the squeezing members inward, the opposing concentric squeezing faces apply an inward, and optionally upward, pressure, more or less evenly around the circumference of the target pimple. The user applies a steady pressure to bring the squeezing members together, thereby increasing the pressure against and within the pimple. If the squeezing faces are angled, the force applied against the walls of the pimple is vectored upward and inward as the squeezing faces come together and consequently the pressure produced within the pimple is selectively directed against the upper inside portion of the wall of the pimple and the contents can be expelled out of the head of the pimple. BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1A shows a perspective view of a first preferred embodiment of the device of the present invention. FIGS. 1B and 1C show a front facing view of the same embodiment in an open and a closed configuration, respectively. FIGS. 1D and 1E show a profile view of the same embodiment applied to a skin surface in an open and closed configuration, respectively. FIGS. 1F and 1G show a top perspective view of the same embodiment in an open configuration and FIGS. 1H and 1I show a top perspective view of the embodiment in a closed configuration. [0020] FIGS. 2A and 2B show perspective views of a second preferred embodiment in an open and closed configuration, respectively. FIGS. 2C and 2D show a front face of the same device in an open and closed position; respectively. FIG. 2E shows a profile view of the same device. FIGS. 2F and 2G show a top view of the same device in an open position and FIGS. 2H and 2I show a top view of the same device in a closed position. [0021] FIGS. 3A and 3B show a top view and a side view, respectively, of a third preferred embodiment of the present invention in an open configuration and FIGS. 3C and 3D show a top view and a side view, respectively, of the same device in a closed configuration. [0022] FIGS. 4A and 4B show a top view and a side view, respectively, of a fourth preferred embodiment of the present invention in an open configuration and FIGS. 4C and 4D show a top view and a side view, respectively, of the same device in a closed configuration. [0023] FIGS. 5A and 5B show a top view and a side view, respectively, of a fifth preferred embodiment in an open configuration with FIG. 5C providing an expanded, partial detail view from FIG. 5B . FIGS. 5D and 5E show a top view and a side view, respectively, of the same device in a closed configuration. [0024] FIGS. 6A and 6B show a top view and a side view, respectively, of a sixth preferred embodiment in an open configuration with FIG. 6C providing an expanded, partial detail view from FIG. 6B . FIGS. 6D and 6E show a top view and a side view, respectively, of the same device in a closed configuration. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0025] A preferred embodiment of the present invention, as shown in FIGS. 1A through 1E , comprises a U-shaped device with two lateral arms, a tension bridge connecting the lateral arms and a distal squeezing interface extending from the open end of the arms. The squeezing members in this embodiment comprise two opposing squeezing arms, each of which extends in a forward direction off one of the two lateral arms and two squeezing faces, each comprising a concave recess along an interior side of the opposing squeezing arms. [0026] A section on each of the lateral arms is of a suitable width and length to securely accommodate a user's fingers or knuckles. Optionally, the two lateral arms may comprise approximately thumb-sized round and, optionally concave opposing grasping sections to securely accommodate a user's fingers. These grasping sections may comprise a material which will improve user comfort and grip, such as a textured plastic or soft rubber, or any other material which will be familiar to one skilled in the art. [0027] The device may be grasped using one finger along each arm, preferably at the finger-holds. The device may be closed by squeezing against the outward tension provided by the tension bridge until the opposing squeezing arms are brought together. The lateral arms of this embodiment are bowed outward to provide an optimal grasping and squeezing configuration. When the squeezing arms are pushed together into a closed position, the two opposing squeezing faces form the walls of an approximately elliptically-shaped lumen. [0028] The squeezing arms may be affixed along the entire portion of the bottom of the lateral arms and may extend off the lateral arms at an angle from approximately 0 to approximately 160 degrees, preferably at about 45 to 65 degrees, relative to the front edge of the lateral arm. The bottom portion of the lateral arm also may be angled or sloped from the front edge of the lateral arm to the back edge of the later arm. The angle or angles provided by the juncture of the squeezing arm to the lateral arm and the slope of the bottom of the lateral arm all may be selected to provide optimum visibility of the squeezing interface, to provide the optimum contact between skin and squeezing interface and to minimize contact with the body by portions of the device other than the squeezing interface. [0029] A portion of the squeezing arms may optionally be curved or bowed downward, toward the skin, preferably such that the apex of the curve coincides approximately with the center of the squeezing face. The degree of the curvature across the bowed portion may be variably selected to optimally position the center of the squeezing faces at the deepest, centermost base of the pimple. [0030] The squeezing faces may be angled from approximately 0 degrees to approximately 85 degrees sloping upward and outward, from the inside bottom portion of the squeezing face to the outside top portion of the squeezing face. In this angled configuration, the bottom circumference of the lumen is smaller than the circumference of the top portion of the lumen such that as the squeezing faces come together, the forces against the circumference of the pimple walls are vectored upward. In this way, the contents of the pimple may be expelled preferably out of the top of the pimple. The device in this embodiment is designed to further allow the user to lift the squeezing interface away from the surface of the skin in a closed or partially closed position to use the angled squeezing faces to force or “squeegee” the contents of the pimple from the bottom or base of the pimple, out of the top of the pimple. [0031] The squeezing interface of the present invention optionally may also comprise a pair or pairs of spherical or partially-spherical protruding skin guides located on the squeezing arms approximately adjacent to one or both ends of the squeezing faces. As the opposing squeezing arms come together, the bottom rounded portion of the skin guides pass along the surface of the skin, and the protuberance guides or rolls the skin ahead, above and below the squeezing face. This action is designed to assist in the collection of the body of the pimple into the lumen and to further prevent the pulling and cutting associated with conventional pimple popping methods and devices. [0032] A second preferred embodiment of the present invention, as shown in FIGS. 2A through 2I , comprises an ergonomic knob adapted to allow the user to more securely grasp the device and to provide additional comfort precision during use. The ergonomic knob may be adapted to fit into the user's palm. In this preferred embodiment, an ergonomic rounded bulb-like handle is affixed at the top portion of the device, at or around the juncture of the two opposing lateral arms. The user of this embodiment may grasp the ergonomic knob in the crux of the palm for additional comfort and stability while using fingers to grasp and squeeze the lateral arms, preferably at finger holds provided thereon. Optionally, the ergonomic knob may have a flattened surface, preferably at the top, which provides the knob with the additional ability to function as a stand such that the device may be rested on a surface to avoid having the squeezing faces coming into contact with any contaminating surfaces. [0033] A third preferred embodiment of the present invention, as shown in FIGS. 4A through 4E , comprises an inner mounting ring on which are mounted two or more squeezing members and a deployment interface which transfers forces applied by the user to the squeezing members and ultimately to the pimple. In this embodiment, the squeezing members are moveably affixed to the mounting ring such that the squeezing members may be moved concentrically inward to apply pressure to a pimple via the opposing squeezing faces. Means for affixing the squeezing members to the mounting ring may comprise, among other well-known means, a pivot or a slot in combination with a spring means for returning the squeezing members to an open, pre-deployment position. [0034] The deployment interface comprises an outer, approximately horseshoe-shaped open ring comprising a guide surface for contacting the squeezing members and gripping means for holding the device and actuating the squeezing members. In this embodiment, a handle extends off each bottom end of the open ring such that they the handles may be gripped and brought together by the user, thereby partially closing the open ring and causing the guiding surfaces to contact the squeezing members, pushing them into a closed or partially closed position. When the device is fully deployed, the handles are brought together along their inner faces. [0035] The open ring may be hinged at an apex to allow the ring to partially close, with the hinge being provided in combination with spring means for providing squeezing resistance and a returning force to urge the ring back into an open position. Alternatively, the open ring may comprise an elastic portion which allows the ring to partially close upon application of pressure by the user and to re-open once the pressure is released. [0036] In a fourth preferred embodiment, as shown in FIGS. 3A through 3C , the handles extending off a bottom portion of the open ring are replaced by gripping means located on opposite sides of the open ring. Preferably, the gripping means are adapted to fit two of the user's fingers such that the familiar squeezing motion of the user's fingers will be applied via the device more uniformly and safely around the circumference of the pimple. [0037] A fifth preferred embodiment, as shown in FIGS. 5A through 5E , comprises multiple squeezing members, with some squeezing members affixed to an inner mounting ring, and optionally with some squeezing member affixed directly to a deployment interface. [0038] A sixth preferred embodiment, as shown in FIGS. 6A through 6E , comprises a deployment interface connected directly to squeezing members. Two or more squeezing members are connected directly to one of two opposing gripping means, via squeezing arms, to form a squeezing assembly. The opposing squeezing assemblies are both affixed to a central bracketing means which allows the user to slide the opposing squeezing assemblies together in a guided, controlled manner. As the user deploys the squeezing members inward, through the travel area allowed by the bracketing means, pairs of guiding ridges incorporated into the bracketing means deflect the squeezing arms of a squeezing assembly toward each other, causing the squeezing faces to come together at a concentric point. [0039] The device in these embodiments may also be used as a more traditional comedone extractor. When the squeezing interface is fully closed, the blackhead may be encircled by the lumen provided by the squeezing faces and the user may thereby apply appropriate pressure to the skin surrounding the blackhead to force the trapped contents of the blackhead out and to the surface of the skin. [0040] The materials used in the construction of any of the components of the devices of the present invention can be chosen from among all metals, rubbers, plastics, composite materials and any combination thereof, the various advantages and disadvantages of which will be obvious to one of ordinary skill in the art. [0041] The foregoing descriptions of specific embodiments thereof are provided by way of examples of the present invention. It will be apparent to one skilled in the art that various changes, combinations and modifications thereof can be made without departing from the spirit and scope of the present invention.	A device and method used for the evacuation of matter beneath an area of skin comprising a squeezing interface comprising approximately concentric squeezing surfaces which apply pressure around the area of skin to force said matter from beneath the skin.	0
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a Continuation of U.S. Ser. No. 13/091,890, filed on Apr. 21, 2011, titled “Systems and Methods for Measuring Bearing Endplay”, and published as U.S. Publication No. US20120079893A1 on Apr. 5, 2012. This application also relates to U.S. application Ser. No. 13/019,583, filed Feb. 2, 2011, titled “Systems and Methods for Adjusting Bearing Endplay”, and published as U.S. Publication No. US20120079922A1 on Apr. 5, 2012, U.S. application Ser. No. 12/951,727, filed Nov. 22, 2010, titled “Systems and Methods for Measuring Bearing Endplay”, and published as U.S. Publication No. US20120079892A1 on Apr. 5, 2012, U.S. application Ser. No. 12/492,826, filed Jun. 26, 2009, titled “Systems And Methods For Preloading A Bearing And Aligning A Lock Nut”, issued as U.S. Pat. No. 8,316,530 on Nov. 27, 2012, U.S. application Ser. No. 11/341,948, filed Jan. 27, 2006, and titled “Method And Apparatus For Preloading A Bearing,” issued as U.S. Pat. No. 7,559,135 on Jul. 14, 2009, U.S. application Ser. No. 11/354,513, filed Feb. 15, 2006, and titled “Method, Apparatus, and Nut for Preloading a Bearing”, issued as U.S. Pat. No. 7,389,579 on Jun. 24, 2008, and U.S. Provisional Application No. 61/388,806, filed Oct. 1, 2010, and titled “Systems and Methods for Preloading a Bearing and Aligning Lock Nut”, each of which is incorporated herein by reference. TECHNICAL FIELD The present invention relates, generally, to methods and apparatus for preloading antifriction bearings in drive trains, particularly, to preloading and adjusting bearings while monitoring the preload being applied. BACKGROUND OF THE INVENTION Various means have been devised to simplify the adjustment of axle bearings, specifically, truck axle bearings. It is generally accepted that in some bearing installations, for example, axle bearings, the life of the bearing will be optimized if the adjustment is made for a slight axial compressive deflection, for example, about 0.003 inches (where this amount is the compressive deflection of the two bearings combined), which is often referred to as “a three thousandths preload.” Typical prior art methods of creating these preloads are obtained by applying specified torques to the bearing assembly, for example, by tightening the nut that retains the bearings. However, for several reasons, it is typically extremely difficult to achieve such preload settings under actual in-field conditions, such as in a mechanic shop. For example, the assembly of a heavy truck wheel onto a wheel hub assembly is a relatively cumbersome procedure that hinders the mechanic. Moreover, the wheel hub assembly always includes at least one inner seal, usually a lip type of seal, which can impose a resistive drag torque component to the preload torque, particularly when the seal is new. In one example, a user may tighten a nut holding a bearing on a shaft to a particular torque and then such nut may be loosened to a particular position by referencing an index mark on a face of the nut a particular distance. Such a nut could be turned a particular portion of a rotation by referencing such a marking, e.g., half a turn. Such an adjustment is a particularly inexact procedure given that wheel nut adjustment is desired to have precision of 0.001 of an inch while the degree of rotation of a nut as described is relatively inexact. Lock nut systems using a single nut are often utilized to retain a wheel or hub assembly, including axle bearings, on a shaft. Such lock nut systems may be connected to a shaft and inhibit rotation of a retaining nut relative to such shafts. For example, such systems are often utilized on motor vehicles, such as axles and wheel ends. Typically, a lock nut will be engageable with a locking member or keeper which inhibits movement of the nut relative to the shaft. The locking member may include a protruding portion which extends into a slot or receiving portion of a shaft. The locking member may also engage the nut such that there is little or no movement between the nut and shaft. Thus, a need exists for providing accurate and repeatable procedures and devices for providing and adjusting bearing preload and for adjusting lock nut systems configured to retain preloaded bearings. SUMMARY OF THE INVENTION The present provides, in a first aspect, a system for use in measuring an end play of a bearing of a wheel hub assembly which includes a follower configured to extend through an opening in a cover connected to a wheel hub. The cover covers the wheel hub such that the cover inhibits access to an end of a shaft of the wheel hub assembly, and the follower is configured to contact the end through the opening. The follower is received in a holder engageable with the cover such that the follower is movable relative to the cover and the holder to allow the follower to extend from the holder to contact the end of the shaft. A frame has a cavity receiving a measurement probe extending outwardly from the cavity. The probe contacts the follower and is configured to measure movement of the follower relative to the wheel hub to determine endplay of a bearing of the hub assembly on the shaft. The frame includes a plurality of legs extending from the frame to a hub mounted on the shaft and coupled to the bearing to support the frame relative to the hub. The present invention provides, in a second aspect, a method for determining an endplay of a bearing of a wheel hub assembly mounted on a shaft which includes extending a follower through an opening in a hub cover covering a hub of the wheel hub assembly and extending away from the hub The follower contacts an end of the shaft. A plurality of legs of an endplay measuring apparatus is connected to the hub of the hub assembly mounted on the shaft. A measuring probe is received in a cavity of a frame of the apparatus. The probe contacts the follower. A force is applied to the apparatus to move the hub in a first axial direction until a cessation of movement of the hub. A first measurement of the probe is determined. A force is applied on the apparatus in a second axial direction opposite to the first axial direction until a second cessation of movement of the hub. A second measurement of the probe is determined after the second cessation of movement. A movement of the follower by the probe is determined to determine an endplay of the bearing by comparing the first measurement to the second measurement. BRIEF DESCRIPTION OF THE DRAWINGS The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of aspects of the invention taken in conjunction with the accompanying drawings in which: FIG. 1 is a perspective view of a system for measuring endplay on a bearing of a wheel hub assembly mounted on a shaft in accordance with the present invention; FIG. 2 is a side cross-sectional view of the system of FIG. 1 ; FIG. 3 is a side cross-sectional view of the follower, holder and hub cover of FIG. 1 ; and FIG. 4 is a perspective view of the follower and holder of FIG. 1 . DETAILED DESCRIPTION OF THE INVENTION In accordance with the principals of the present invention, systems and methods for adjusting bearings mounted on a shaft are provided. In an exemplary embodiment depicted in FIG. 1 , a system 10 for measuring end play is mounted on a wheel hub assembly 20 . Wheel hub assembly 20 is an assembly that would typically be found on a front or rear axle of a cab or tractor of a tractor-trailer, or an axle of a trailer. However, aspects of the invention are not limited to use for vehicle bearings. As will generally be understood by those skilled in the art, aspects of the invention may be used to service bearings and bearing assemblies in any machine or device that employs bearings, including, but not limited to: power trains, transmissions, machine components, on and off-road vehicles, aircraft wheels, marine drives, spacecraft, conveyor rolls, and windmills, among others. According to aspects of the present invention, system 10 may be used in these and any other assembly for which bearing preload and/or endplay is desired, for example, any assembly that utilizes thrust and radial load carrying bearings that are indirectly mounted. As shown in FIGS. 1-2 , for example, wheel hub assembly 20 includes a wheel hub or, simply, a hub 12 , a threaded, spindle, axle, or a shaft 14 . As is typical, shaft 14 is mounted on two antifriction bearings and shaft 14 includes an exposed end 13 , which is typically threaded on the outside diameter and is partially hollow at the end. A retaining nut 11 ( FIG. 2 ) may be threaded to exposed end 13 to retain hub 12 thereon. As shown in FIG. 2 , as is typical of bearings, outboard bearing 16 includes an inner race (or cone) 15 , an outer race (or cup) 17 , a plurality of rollers 22 , and a roller cage 24 . Similarly, an inboard bearing 19 includes an inner race (or cone) (not shown), an outer race (or cup) (not shown), a plurality of rollers (not shown), and roller cage (not shown). The details of an inboard bearing and an outboard bearing are described and depicted in co-owned U.S. Pat. No. 7,303,367, issued Dec. 4, 2007 (application Ser. No. 11/029,531 filed Jan. 5, 2005), entitled “Lock Nut System”; U.S. Publication No. 2007/0177829A1, published Aug. 2, 2007, (application Ser. No. 11/341,948 filed Jan. 27, 2006), entitled “Method and Apparatus for Preloading a Bearing”; and U.S. Pat. No. 7,389,579, issued Jun. 24, 2008 (application Ser. No. 11/354,513, filed Feb. 15, 2006), entitled “Method, Apparatus, and Nut for Preloading a Bearing”, the entirety of which are incorporated herein by reference. As depicted in FIGS. 5-8 of co-owned U.S. Provisional Application No. 61/388,806, filed Oct. 1, 2010, entitled “Systems and Methods for Preloading a Bearing and Aligning Lock Nut”, for example, retaining nut 11 may be a locking nut as disclosed in co-owned U.S. Pat. No. 7,303,367 (application Ser. No. 11/029,531 filed Jan. 5, 2005), entitled “Lock Nut System”; U.S. Publication No. 2007/0177829A1 (application Ser. No. 11/341,948 filed Jan. 27, 2006), entitled “Method and Apparatus for Preloading a Bearing”; and U.S. Pat. No. 7,389,579 (application Ser. No. 11/354,513, filed Feb. 15, 2006), entitled “Method, Apparatus, and Nut for Preloading a Bearing”. In another example, a retaining nut could be a locking nut as disclosed in U.S. Pat. No. 3,762,455 to Anderson Jr. In the conventional art, retaining nut 11 typically is used to secure a wheel (e.g., wheel 200 , FIG. 3 ) or hub assembly to non-rotating axle or spindle 14 . However, in aspects of the present invention, retaining nut 11 may be useful in varying the preload and/or endplay of bearing 16 . Bearing 16 may be a tapered roller bearing, or aspects of the invention may be applied to other types of antifriction bearings for which it is desirable to provide preload and/or endplay, for example, spherical roller bearings, deep groove ball bearings, and the like. As described above, it is desirable for an adjustment to be provided to a bearing assembly such that a desired amount of endplay is present. After retaining nut 11 is tightened on the shaft to a particular predetermined torque (e.g., using a torque wrench), the standard procedures call for a loosening of say ¼ turn to create a desirable endplay of bearing 16 on shaft 14 . All typical adjustment procedures require that said endplay be measured with a dial indicator to assure a safe adjustment had been achieved. System 10 may include a frame 30 formed of a plurality of cross members 35 . Frame 30 may be connected to a handle 40 at one end of system 10 by connecting legs 45 . Frame 30 may also be connected to pressing legs 50 which may extend from frame 30 away from handle 40 and to wheel hub 12 as depicted in the figures. Pressing legs 50 may be connected to wheel hub 12 at wheel lugs 60 . Connecting tabs 55 may be connected to, or monolithic relative to, pressing legs 50 and may be aligned in a direction substantially perpendicular to pressing legs 50 , such that connecting tabs 55 may be received under lug nuts 70 threaded onto wheel lugs 60 . Pressing legs 50 may be substantially parallel to each other and may be connected to wheel hub 12 such that the legs are substantially parallel to the axis (i.e., longitudinal axis) of shaft 14 . Connecting legs 45 may also be substantially parallel to the axis of shaft 14 . Each connecting leg and pressing leg on a same side of frame 30 may be monolithic to, or connected to, one another. The cross members (i.e., cross members 35 ) may be connected on each side thereof to at least one of pressing legs 50 and connecting legs 45 . A hubcap 80 may be connected to hub 12 via screws 81 or other connecting mechanisms as is known in the art. A follower 82 may be received in a holder 85 which is received in an opening 83 through hubcap 80 such that holder 85 is connected to, or contacts, hubcap 80 to inhibit movement of holder 85 through opening 83 toward shaft 14 . A resilient member 86 (e.g., a spring) may be connected to follower 82 and holder 85 such that a distal end 84 of follower 82 is biased toward shaft 14 and away from probe 90 . As used herein, follower refers to any structure, or part of a structure, which contacts shaft 14 and extends to holder 85 such that the follower extends through the holder toward handle 40 . A dial indicator or probe 90 may be received in a cavity 95 of frame 30 such that probe 90 is stationary relative to frame 30 and a remainder of system 10 . For example, probe 90 may be connected to cross members 35 in any number of ways, such as by welding or by mechanical fasteners. Frame 30 may include an opening 32 to allow user to view a display 34 of a dial indicator of probe 90 . A probe tip 100 of a probe stem 99 may contact follower 82 when follower 82 is received in holder 85 such that end 83 of follower 82 contacts shaft 14 . Probe tip 100 may be aligned in a direction substantially parallel to an axis of shaft 14 . For example, an axis of probe tip 100 may be substantially aligned with the longitudinal axis of shaft 14 . When a measurement of endplay of hub assembly 20 , including wheel hub 12 and bearing 16 , is desired, a user may grasp handle 40 and push in a first direction toward hub 12 until no further forward motion occurs. Probe 90 may then be reset to a known setting (e.g., ‘zeroed’) to allow a measurement by probe 90 which it is in contact with follower 82 . The user may then pull in a second direction on handle 40 until no further reverse motion of hub 12 occurs. The user may then view display 34 to determine a measurement of the movement of hub 12 relative to the follower as determined by the movement of probe 90 which is in contact with the face of the follower. The movement by the probe signals a distance on the display which indicates the endplay of wheel hub 12 and bearing 16 . The difference between a movement after forward motion of the hub ceases to that after reverse motion of the hub ceases provides an indication of the endplay of bearing 16 . The components of system 10 (e.g., the connecting legs, extending legs, handle, tabs, and frame) may be sufficiently rigid to allow the application of a force (e.g., in a forward and reverse axial direction relative to shaft 14 ) to handle 40 to transfer such force to hub 12 to allow the motion of hub 12 in a forward and reverse direction to allow the measurement of the endplay as described. Further, as described above probe 90 is connected to frame 30 . The connection of probe 90 to frame 30 may be fixed as described above or could be adjustable. For example, probe 90 may be connected to a plate 33 which has screws or other connectors received in slots of frame 35 such that probe 90 may be adjusted to a particular position and tightened by the screws or fasteners to frame 35 if further adjustment is desired. After the measurement of endplay described above (or prior thereto) it may be desirable to tighten nut 11 to adjust such endplay. As depicted in FIG. 1 , openings 52 may be present between connecting legs 50 on opposite sides of system 10 . A user may insert a wrench (not shown) into one of openings 52 to engage the wrench with a nut 11 to adjust an endplay of bearing 16 and hub 12 . Prior to any such adjustment, however, hubcap 80 is removed to allow access of a wrench to nut 11 . As described above and depicted in FIG. 1 , endplay may be measured by system 10 with tabs 55 placed on wheel hub 12 and held in place by wheel lugs 60 . In another example, tabs 55 could be received on top of wheel 200 connected to hub 12 as depicted in FIG. 3 of co-owned U.S. application Ser. No. 12/951,727. In a further unillustrated example, follower 80 could be replaced by a follower of a different axial dimension or thickness to accommodate a height of hubcap from a hub or a dimension of a opening (e.g., opening 83 ) through a hubcap (e.g., hubcap 80 ), or another structure mounted on hub 12 which restricts access to shaft 14 by a system for measuring end play (e.g., system 10 ). As described above, handle 40 may be grasped by a user and a force may be applied thereto to move bearing 16 and hub 12 to a first position followed by a “zeroing” of the probe and then movement to a second position. During the application of force to the first position and movement from the first position to the second position, handle 40 may be utilized to rotate system 10 and thus hub 12 and bearing 16 . This rotation insures roller alignment of the bearing such that the measured endplay is accurate for the circumference of hub 12 and bearing 16 . Also, pressing legs 55 are located on opposite sides of system 10 and are located about 180° apart relative to the axis of shaft 14 . The positioning of such pressing legs substantially equally distant from one another and connected to handle 40 via connecting legs 45 promotes an equidistant application of force to hub 12 and bearing 16 when a force is applied to handle 40 described above such that twisting of the hub is minimized and an accurate measurement of endplay may be achieved and an off-center loading of the bearing may be avoided. Handle 40 may also extend substantially perpendicularly relative to the axis of shaft 14 and may extend through the axis to opposite sides of such axis as depicted in the figures. In particular, handle 40 may connect to connecting legs 45 , and connecting legs 45 may extend substantially parallel to the axis of shaft 45 and pressing legs 50 may also extend substantially parallel to the axis of shaft 45 such that connecting legs 50 may contact hub 12 . As described above, pressing legs 50 may connect to tabs 55 which extend substantially perpendicularly to pressing legs 50 . It will be understood by one skilled in the art that pressing legs 50 could connect to hub 12 in any number of other ways while satisfying the objectives of the invention. Although aspects of the present invention were described above with respect to their application to wheel hub assemblies, for example, truck wheel hub assemblies, it is understood that aspects of the present invention may be applied to any vehicle, machine, or component having at least one bearing. While several aspects of the present invention have been described and depicted herein, alternative aspects may be effected by those skilled in the art to accomplish the same objectives. Accordingly, it is intended by the appended claims to cover all such alternative aspects as fall within the true spirit and scope of the invention.	A system for use in measuring an end play of a wheel hub assembly includes a follower configured to extend through an opening in a cover connected to a wheel hub. The cover covers the wheel hub such that the cover inhibits access to an end of a shaft of the wheel hub assembly, and the follower is configured to contact the end through the opening. The follower is received in a holder engageable with the cover such that the follower is movable relative to the cover and the holder to allow the follower to extend from the holder to contact the end of the shaft. A frame has a cavity receiving a measurement probe extending outwardly from the cavity. The probe contacts the follower and is configured to measure movement of the follower to determine endplay of the bearing assembly on the shaft. The frame includes a plurality of legs extending from the frame to a hub mounted on the shaft and coupled to the bearing to support the frame relative to the hub.	5
RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 14/309,003, filed on Jun. 19, 2014 and issued as U.S. Pat. No. 9,143,037 on Sep. 22, 2015, which is a continuation of PCT/US2012/070555, filed on Dec. 19, 2012 which claims the benefit of the priority date of U.S. Provisional Application No. 61/577,271 filed on Dec. 19, 2011, the contents of which are herein incorporated by reference. FIELD OF DISCLOSURE [0002] This disclosure relates to the control of power converters that utilize capacitors to transfer energy. BACKGROUND [0003] Power converters may generally include switches and one or more capacitors. Such converters can be used, for example, to power portable electronic devices and consumer electronics. [0004] A switch-mode power converter is a specific type of power converter that regulates an output voltage or current by switching energy storage elements (i.e. inductors and capacitors) into different electrical configurations using a switch network. [0005] A switched capacitor converter is a type of switch-mode power converter that primarily utilizes capacitors to transfer energy. In such converters, the number of capacitors and switches increases as the transformation ratio increases. [0006] Typical power converters perform voltage transformation and output regulation. In many power converters, such as buck converters, both functions take place in a single stage. However, it is also possible to split these two functions into two specialized stages. Such two-stage power converter architectures feature a separate transformation stage and a separate regulation stage. The transformation stage transforms one voltage into another voltage, while the regulation stage ensures that the output voltage and/or output current of the power converter maintains desired characteristics. [0007] For example, referring to FIG. 1 , in one known power converter 10 , a switched capacitor element 12 A is electrically connected, at an input end thereof, to a voltage source 14 . An input of a regulating circuit 16 A is electrically connected to an output of the switched capacitor element 12 A. A load 18 A is then electrically connected to an output of the regulating circuit 16 A. Such a converter is described in US Patent Publication 2009/0278520, filed on May 8, 2009, the contents of which are herein incorporated by reference. [0008] Furthermore, a modular multi-stage power converter architecture is described in PCT Application PCT/2012/36455, filed on May 4, 2012, the contents of which are also incorporated herein by reference. The switched capacitor element 12 A and the regulating circuit 16 A can be mixed and matched in a variety of different ways. This provides a transformative integrated power solution (TIPS™) for the assembly of such power converters. As such, the configuration shown in FIG. 1 represents only one of multiple ways to configure one or more switched capacitor elements 12 A with one or more regulating circuits 16 A. [0009] FIG. 2 illustrates a power converter 10 A that receives an input voltage VIN from the voltage source 14 and produces an output voltage VO that is lower than the input voltage VIN. The power converter 10 A is a particular embodiment of the power converter architecture illustrated in FIG. 1 . The switched capacitor element 12 A features a 2:1 dual-phase series-parallel switched capacitor network that includes power switches S 1 -S 8 and pump capacitors C 1 -C 2 . In contrast, the regulating circuit 16 A features a buck converter that includes a low-side switch SL, a high-side switch SH, a filter inductor L 1 , and a driver stage 51 . [0010] In the operation of the switched capacitor element 12 A, the power switches S 1 , S 3 , S 6 , S 8 and the power switches S 2 , S 4 , S 5 , S 7 are always in complementary states. Thus, in a first network state, the power switches S 1 , S 3 , S 6 , S 8 are open and the power switches S 2 , S 4 , S 5 , S 7 are closed. In a second network state, the power switches S 1 , S 3 , S 6 , S 8 are closed and the power switches S 2 , S 4 , S 5 , S 7 are open. The switched capacitor element 12 A cycles through the first network state and the second network state, resulting in an intermediate voltage VX that is one-half of the input voltage VIN. [0011] Referring to FIG. 2 , the switched capacitor element 12 A is in the first network state when a first phase voltage VA is low and a second phase voltage VB is high. In contrast, the switched capacitor element 12 A is in the second network state when the first phase voltage VA is high and the second phase voltage VB is low. The two phase voltages VA, VB are non-overlapping and have approximately a fifty percent duty cycle. [0012] In the operation of the regulating circuit 16 A, the low-side switch SL and the high-side switch SH chop the intermediate voltage VX into a switching voltage VLX. A LC filter receives the switching voltage VLX and generates the output voltage VO that is equal to the average of the switching voltage VLX. To ensure the desired output voltage VO, a regulation control voltage VR controls the duty cycle of the low-side switch SL and the high-side switch SH. Additionally, the driver stage 51 provides the energy to open and close the low-side and high-side switches SL, SH. [0013] Previous disclosures treat the control of the switched capacitor element 12 A and regulating circuit 16 A separately. This has numerous disadvantages, one of which is that the intermediate voltage VX ripple will feed through to the output voltage VO. A possible solution to this problem is to create a feed-back control loop that is fast enough to attenuate the effect of the intermediate voltage VX ripple on the output voltage VO. To achieve this goal, the frequency of the regulating circuit 16 A must be at a significantly higher frequency than the frequency of the switched capacitor element 12 A. [0014] Another possible solution to this problem would be to add a feed-forward control loop to the regulating circuit 16 A. However, as was the case with the fast feed-back solution, the feed-forward solution will only be effective if the frequency of the regulating circuit 16 A is significantly higher than the frequency of the switched capacitor element 12 A. Therefore, both solutions place a severe frequency constraint on the switched capacitor element 12 A and the regulating circuit 16 A. [0015] Furthermore, there is typically a dead-time interval DT between the first network state and the second network state of the switched capacitor element 12 A. During the dead-time interval DT, all of the switches in the switched capacitor element 12 A are open. This ensures a clean transition between the first network state and the second network state of the switched capacitor element 12 A, and vice versa. If the regulating circuit 16 A tries to draw current during the dead-time interval DT, a voltage ‘glitch’ will occur at the node between the switched capacitor element 12 A and the regulating circuit 16 A. [0016] The voltage ‘glitch’ can be reduced through the use of a glitch capacitor CX. Unfortunately, a portion of the energy stored on the glitch capacitor CX is thrown away each time the switched capacitor element 12 A transitions between the first network state and the second network state, and vice versa. The energy loss is a result of the glitch capacitor CX being shorted to capacitors at a different voltage, such as pump capacitors C 1 , C 2 . Therefore, the use of a glitch capacitor CX to supply energy during the dead-time interval DT is an effective solution, but requires one additional capacitor and reduces the efficiency of the power converter 10 A. SUMMARY [0017] In one aspect, the invention features an apparatus for power conversion. Such an apparatus includes a first element configured to accept an input signal having a first voltage and to output an intermediate signal having a second voltage, and a second element configured to receive the intermediate signal from the first element and to output an output signal having a third voltage. The first element is either a voltage transformation or a regulating element. The second element is a regulating element when the first element is a voltage transformation element and a voltage transformation element otherwise. A controller is configured to control a period of the voltage transformation element and a period of the regulating element. The controller is configured to synchronize the period of the voltage transformation element with a product of a coefficient and the period of the regulating element. This coefficient can be either a positive integer or a reciprocal of the integer. [0018] In some embodiments, the coefficient is a positive integer, whereas in others, it is a reciprocal of the positive integer. [0019] Embodiments also include those in which the controller receives the intermediate signal from the first element and the output signal from the second element. Among these are those in which the controller receives the input signal, and also those in which the controller generates a first control signal based on the output signal and sends the first control signal to the regulating element. This embodiment also includes within its scope alternative embodiments in which the controller generates a second control signal based on the intermediate signal and the first control signal, and sends the second control signal to the voltage transformation element. [0020] Also included within the scope of the invention are those embodiments in which the controller provides linear voltage-mode control, and those in which it provides peak current-mode control. [0021] In some embodiments, regulating element passes continuous current therethrough, whereas in others, the regulating element passes discontinuous current therethrough. [0022] In other embodiments, the voltage transformation element includes voltage transformation sub-elements and the regulating element includes regulating sub-elements, and each voltage transformation sub-element is associated with a corresponding one of the regulating sub-elements. [0023] Embodiments also include those in which the first element includes a voltage transformation element and those in which the first element includes a regulating element. [0024] In another aspect, the invention features an apparatus for power conversion, such an apparatus includes a voltage transformation element, a regulating element, and a controller. A period of the voltage transformation element is equal to a product of a coefficient and a period of the regulating circuit. The coefficient is either a positive integer or a reciprocal of the integer. [0025] Embodiments include those in which the regulating element passes continuous current therethrough, and also those in which the regulating element passes discontinuous current therethrough. [0026] In some embodiments, the controller controls multiple phases present in the regulating element and the voltage transformation element. [0027] Other embodiments include a data processing unit and a memory unit, at least one of which is configured to consume power provided by the power converter circuit. [0028] Additional embodiments include data processing unit, a display, and a wireless transmitter and receiver, at least one of which is configured to consume power provided by the power converter circuit. DESCRIPTION OF THE FIGURES [0029] The foregoing features of the circuits and techniques described herein, may be more fully understood from the following description of the figures in which: [0030] FIG. 1 shows a known power converter architecture; [0031] FIG. 2 shows a particular implementation of the power converter architecture in FIG. 1 ; [0032] FIG. 3 shows a controller coupled to the power converter in FIG. 2 ; [0033] FIG. 4 shows a particular implementation of the controller in FIG. 3 ; [0034] FIG. 5 shows a timing diagram of relevant signals from the embodiment in FIG. 4 . [0035] FIG. 6 shows a close-up of selected signals in FIG. 5 ; [0036] FIG. 7 shows a DC model of a switched capacitor element; [0037] FIGS. 8A-8B show the relationship between the load current and the intermediate voltage ripple; [0038] FIG. 9 shows a controller that synchronizes a regulating circuit that precedes a switched capacitor element; [0039] FIG. 10 shows a three-phase controller that synchronizes a three-phase switched capacitor element that precedes a three-phase regulating circuit; [0040] FIG. 11 shows a particular implementation of the three-phase controller in FIG. 10 ; and [0041] FIGS. 12A-12B show timing diagrams of relevant signals from the embodiment in FIG. 11 . DETAILED DESCRIPTION [0042] The apparatus described herein provides a way to control the switched capacitor element 12 A and the regulating circuit 16 A in a modular multi-stage power converter architecture. [0043] Before describing several exemplary embodiments of controllers for power converters that utilize capacitors to transfer energy, it should be appreciated that in an effort to promote clarity in explaining the concepts, references are sometimes made herein to specific controllers for power converters that utilize capacitors to transfer energy. It should be understood that such references are merely exemplary and should not be construed as limiting. After reading the description provided herein, one of ordinary skill in the art will understand how to apply the concepts described herein to provide specific controllers for power converters that utilize capacitors to transfer energy. [0044] It should be appreciated that reference is also sometimes made herein to particular frequencies as well as to particular transformation voltage ratios. It should be understood that such references are merely exemplary and should not be construed as limiting. [0045] Reference may also sometimes be made herein to particular applications. Such references are intended merely as exemplary and should not be taken as limiting the concepts described herein to the particular application. [0046] Thus, although the description provided herein explains the inventive concepts in the context of particular circuits or a particular application or a particular frequency, those of ordinary skill in the art will appreciate that the concepts equally apply to other circuits or applications or frequencies. [0047] Embodiments described herein rely at least in part on the recognition that by synchronizing the switched capacitor element 12 A and the regulating circuit 16 A, the intermediate voltage VX ripple effect on the output voltage VO and the voltage “glitch” can be minimized. [0048] FIG. 3 illustrates a first generic controller 20 that synchronizes the switched capacitor element 12 A and the regulating circuit 16 A within the power converter 10 A shown in FIG. 2 . The first generic controller 20 receives five input signals and provides three output signals. The input signals include the input voltage VIN, the output voltage VO, the intermediate voltage VX, a reference voltage VREF, and a clock voltage VCLK. The output signals include the regulation control voltage VR, the first phase voltage VA, and the second phase voltage VB. The clock voltage VCLK sets the period of the regulation control voltage VR and the reference voltage VREF sets the desired output voltage VO. [0049] Synchronizing the switched capacitor element 12 A with the regulating circuit 16 A causes the intermediate voltage VX ripple to be in phase with the switching voltage VLX. In this scenario, feed-forward control is effective if the frequency of the regulating circuit 16 A is greater than or equal to the frequency of the switched capacitor element 12 A, thereby relieving the severe frequency constraint of separately controlled stages. [0050] Additionally, the glitch capacitor CX, shown in FIG. 2 , can be removed altogether if the dead-time interval DT of the switch capacitor element 12 A occurs when the regulating circuit 16 A is not drawing input current. Synchronizing the switched capacitor element 12 A and the regulating circuit 16 A ensures the proper timing between the dead-time interval DT and the interval during which the regulating circuit 16 A is not drawing input current. [0051] One more benefit of synchronizing the switched capacitor element 12 A and the regulating circuit 16 A is the ability to open and close the power switches S 1 -S 8 in the switched capacitor element 12 A when zero-current is flowing through the power switches S 1 -S 8 . This technique is often referred to as zero-current switching. To achieve zero-current switching, the dead-time interval DT must occur when the regulating circuit 16 A is not drawing input current. [0052] FIG. 4 illustrates a controller 20 A that is a preferred embodiment of the first generic controller 20 . The controller 20 A can be separated into a first control section and a second control section. The control circuitry for the regulating circuit 16 A is in the first control section and includes first, second, third, and fourth control blocks 30 , 31 , 32 , 33 . In contrast, the control circuitry for the switched capacitor element 12 A is in the second control section and includes fifth, sixth, and seventh control blocks 34 , 35 , 36 . The “link” between the fourth control block 33 and the fifth control block 34 enables synchronization of the first and second control sections. [0053] In an effort to promote clarity in explaining the operation of the controller 20 A, FIG. 5 illustrates some relevant signals generated by the controller 20 A. The relevant signals include the clock voltage VCLK, a saw-tooth voltage VSAW, the regulation control voltage VR, the switching voltage VLX, a filter inductor current IL, the intermediate voltage VX, the first phase voltage VA, and the second phase voltage VB. Furthermore, FIG. 6 illustrates a close-up of some of the waveforms in FIG. 5 , where the regulation control voltage period TSW is the inverse of the regulation control voltage VR frequency. [0054] Referring back to FIG. 4 , the first control section within the controller 20 A uses a linear voltage-mode control scheme to control the regulating circuit 16 A. The controller 20 A compares the output voltage VO with the reference voltage VREF, thereby producing a residual voltage that is conditioned by the second control block 31 . A resulting error voltage VERR is then fed into the third control block 32 where it is compared with the saw-tooth voltage VSAW. Lastly, the output of the third control block 32 is further conditioned by the fourth control block 33 , resulting in the regulation control voltage VR. [0055] The first control block 30 sets the frequency of the regulation control voltage VR by generating the saw-tooth voltage VSAW from the clock voltage VCLK. Additionally, the first control block 30 provides feed-forward control of the regulating circuit 16 A by adjusting the peak voltage of the saw-tooth voltage VSAW based upon the intermediate voltage VX. Alternatively, feed-forward control can be implemented by adjusting the error voltage VERR with respect to the input voltage VIN or the intermediate voltage VX in the second control block 31 . [0056] The second control section within the controller 20 A uses a hysteretic control scheme to control the switched capacitor element 12 A. The controller 20 A causes the first and second phase voltages VA, VB to cycle the switched capacitor element 12 A back and forth between the first network state and the second network state based upon a hysteresis band. [0057] During operation, the sixth control block 35 continuously compares the intermediate voltage VX with a trigger voltage VXL. When the intermediate voltage VX drops below the trigger voltage VXL, the fifth control block 34 is triggered and then waits for a confirmation signal. Once the fourth control block 33 sends a signal informing the fifth control block 34 that it is acceptable to make a state change, the dead-time interval DT, shown in FIG. 6 , is initiated. During the dead-time interval DT, the first and second phase voltages VA, VB are set low. Following the dead-time interval DT, either the first phase voltage VA is set high and the second phase voltage VB is left low or the first phase voltage VA is left low and the second phase voltage VB is set high, depending upon the initial state. After the state change, the fifth control block 34 is reset and the sequence repeats. [0058] The controller 20 A thus forces the frequency of the switched capacitor element 12 A to be submultiples of the frequency of the regulating circuit 16 A. This constraint is illustrated in FIG. 5 , where the frequencies of the first phase voltage VA and the second phase voltage VB are much lower than the frequency of the regulation control voltage VR. In some practices, the frequency of the second phase voltage VB is as little as a tenth that of the control voltage VR. [0059] Since the switched capacitor element 12 A is loaded down by a non-capacitive regulating circuit 16 A, the voltage ripple on the intermediate voltage VX is a piecewise linear approximation of a saw-tooth waveform. As used herein, an intermediate peak-peak voltage ripple ΔVX is equal to the maximum intermediate voltage minus the minimum intermediate voltage under steady state conditions. Typically, the intermediate voltage VX comprises a high frequency component from the regulating circuit 16 A superimposed on the lower frequency saw-tooth waveform from the switched capacitor element 12 A. [0060] Unfortunately, while the fifth control block 34 is waiting to change states, the intermediate voltage VX drops a delta voltage ΔVD below the trigger voltage VXL, as shown by the intermediate voltage VX curve in FIG. 5 . Typically, the delta voltage ΔVD is small, especially if the frequency of the switched capacitor element 12 A is much lower than the frequency of the regulating circuit 16 A. The delta voltage ΔVD at most can be equal to one-half of the intermediate peak-peak voltage ripple ΔVX and this occurs when the frequency of the switched capacitor element 12 A is equal to the frequency of the regulating circuit 16 A. [0061] FIG. 7 illustrates a DC model of the switched capacitor element 12 A coupled between the voltage source 14 and the regulating circuit 16 A. The DC model includes a transformer with a finite output resistance RO. Assuming the switched capacitor element 12 A delivers an intermediate current IX, the average of the intermediate voltage VX can be calculated using [0000] V   X _ = V   I   N  N   2 N   1 - I   X × R   O . [0000] The configuration of the switches and capacitors in the switched capacitor element 12 A sets a voltage transformation ratio N 1 :N 2 . Meanwhile, the output resistance RO of the switched capacitor element 12 A accounts for the energy loss in charging/discharging the pump capacitors. [0062] Based upon the waveforms in FIG. 5 , the average of the intermediate voltage VX can be calculated using [0000] VX =VXL−ΔVD+ΔVX/ 2. [0000] By equating the previous two equations, the intermediate peak-peak voltage ripple ΔVX can be expressed as [0000] Δ   V   X = 2  [ V   I   N  N   2 N   1 - I   X × R   O - V   X   L + Δ   V   D ] . [0000] Consequently, the intermediate peak-peak voltage ripple ΔVX is function of operating parameters such as the intermediate current IX and the input voltage VIN. Additionally, due to the synchronization constraint, the intermediate peak-peak voltage ripple ΔVX is also a function of the delta voltage ΔVD. [0063] Unfortunately, large variations in the intermediate peak-peak voltage ripple ΔVX can overstress the regulating circuit 16 A. To minimize variations of the intermediate peak-peak voltage ripple ΔVX, the trigger voltage VXL, shown in FIG. 4 , can be adjusted on the fly. For example, the seventh control block 36 utilizes the input voltage VIN and the intermediate voltage VX to make a decision on the appropriate value of the trigger voltage VXL. Therefore, when the input voltage VIN rises, the trigger voltage VXL rises in step. [0064] One key idea illustrated in FIG. 6 is that the dead-time interval DT occurs during the off state of the high-side power switch SH in FIG. 2 . To ensure this outcome, there is an upper bound on the duty cycle of the regulating circuit 16 A, where a maximum duty cycle DMAX is determined using [0000] D   M   A   X = T   S   W - D   T T   S   W . [0000] As illustrated by the equation above, the dead-time interval DT sets the maximum duty cycle DMAX. It is often desirable to minimize the dead-time interval DT, thereby widening the duty cycle range of the regulating circuit 16 A. [0065] It is not uncommon to have a duty cycle limit, specifically if constant frequency operation of the regulating circuit 16 A is required for electromagnetic compatibility reasons. In these cases, the maximum duty cycle DMAX constraint is not overly burdensome because the feed-back control loop for the regulating circuit 16 A would otherwise have a duty cycle limit. [0066] FIG. 8A illustrates the period of the switched capacitor element 12 A and the intermediate peak-peak voltage ripple ΔVX as a function of the output current. As the output current decreases, the slope of the voltage ripple on the intermediate voltage VX decreases. This reduces the frequency of the first and second phase voltages VA, VB. Due to synchronization, the reduction in frequency occurs abruptly and only at specific output current values. The change in frequency takes place whenever the intermediate peak-peak voltage ripple ΔVX is equal to a maximum peak-peak voltage ripple ΔVMAX divided by two. Consequently, the intermediate peak-peak voltage ripple ΔVX follows a saw-tooth waveform with a fixed valley voltage. Furthermore, as the output current approaches zero, the intermediate peak-peak voltage ripple ΔVX approaches one-half of the maximum peak-peak voltage ripple ΔVMAX. [0067] With a few modifications to the controller 20 A, it is also possible to get the intermediate peak-peak voltage ripple ΔVX to follow a saw-tooth waveform with a fixed peak voltage as illustrated in FIG. 8B . In this scenario, as the output current approaches zero, the intermediate peak-peak voltage ripple ΔVX approaches the maximum peak-peak voltage ripple ΔVMAX. The main difference between the first approach in FIG. 8A and second approach in FIG. 8B is the distribution of frequencies and intermediate peak-peak voltage ripple ΔVX across the output current range. [0068] The controller 20 A depicted in FIG. 4 and described above is one of many possible implementations of the first generic controller 20 that can synchronize the power converter 10 A or any power converter that includes a switched capacitor element 12 A that precedes a regulating circuit 16 A. In the modular multi-stage power converter architecture, the switched capacitor element 12 A and the regulating circuit 16 A can be mixed and matched in a variety of different ways. For example, FIG. 9 illustrates an alternative power converter 10 B, wherein a regulating circuit 16 A precedes a switched capacitor element 12 A. [0069] In FIG. 9 , a second generic controller 21 synchronizes the regulating circuit 16 A and the switched capacitor element 12 A. The input and output signals of the second generic controller 21 are the same as that of the first generic controller 20 . In the power converter 10 B, the regulating circuit 16 A may include various types of switch-mode power converters, such as a boost converter, a resonant converter, and a fly-back converter. Similarly, the switched capacitor element 12 A may include various types of switched capacitor converters, such as a series-parallel charge pump, a voltage doubler, and a cascade multiplier. Regardless of the selection of either the regulating circuit 16 A or the switched capacitor element 12 A, if the two stages are synchronized, the frequency of the switched capacitor element 12 A will change in discrete steps as the output current of the power converter 10 B is varied. [0070] In addition to alternative modular multi-stage power converter architectures, it is also possible to synchronize multi-phase implementations. FIG. 10 illustrates a three-phase power converter 10 C and a generic three phase-controller 22 that synchronizes the various stages. The three-phase power converter 10 C includes three regulating sub-elements: a first regulating circuit 16 A, a second regulating circuit 16 B, a third regulating circuit 16 C and three voltage transformation sub-elements: a first switched capacitor element 12 A, a second switched capacitor element 12 B, and a third switched capacitor element 12 C. The first, second, and third switched capacitor elements 12 A, 12 B, 12 C provide first, second, and third intermediate voltages VX 1 , VX 2 , VX 3 , respectively. [0071] First, second, and third regulation control voltages VR 1 , VR 2 , VR 3 control the first, second, and third regulating circuits 16 A, 16 B, 16 C, respectively. Furthermore, first and second phase voltages VA 1 , VB 1 control the first switched capacitor element 12 A; third and fourth phase voltages VA 2 , VB 2 control the second switched capacitor element 12 B; and fifth and sixth phase voltages VA 3 , VB 3 control the third switched capacitor element 12 C. Additionally, a regulation control bus BVR includes the first, second, and third regulation control voltages VR 1 , VR 2 , VR 3 . A first phase bus BVA includes the first, third, and fifth phase voltages VA 1 , VA 2 , VA 3 . Lastly, a second phase bus BVB includes the second, fourth, and sixth phase voltages VB 1 , VB 2 , VB 3 . [0072] FIG. 11 illustrates a three-phase controller 22 A that is a preferred embodiment of the generic three-phase controller 22 . The three-phase controller 22 A can be separated into a first control section and a second control section. The control circuitry for the first, second, and third regulating circuits 16 A, 16 B, 16 C is in the first control section and includes first, second, third, fourth, fifth, and sixth control blocks 30 , 31 , 32 A, 32 B, 32 C, 33 . In contrast, the control circuitry for the first, second, and third switched capacitor elements 12 A, 12 B, 12 C is in the second control section and includes seventh, eighth, ninth, tenth, and eleventh control blocks 34 , 35 A, 35 B, 35 C, 36 . [0073] The three-phase controller 22 A looks very similar to the controller 20 A in FIG. 4 , but with additional input and output signals. In the three-phase controller 22 A, a linear voltage-mode control scheme is used to control the regulating circuits 16 A- 16 C and a hysteretic control scheme is used to control the switched capacitor elements 12 A- 12 C. Consequently, the operation of the first and second control sections in the three-phase controller 22 A is similar to that described in connection with FIG. 4 . [0074] In the first control section, the first control block 30 sets the frequency and phase of the first, second, and third regulation control voltages VR 1 , VR 2 , VR 3 . The first control block 30 generates first, second, and third saw-tooth voltages VSAW 1 , VSAW 2 , VSAW 3 that are compared to an error voltage VERR by the third, fourth, and fifth control blocks 32 A, 32 B, 32 C, respectively. The resulting three outputs are further conditioned by the sixth control block 33 that produces the regulation control bus BVR. [0075] In the second control section, the first, second, and third intermediate voltages VX 1 , VX 2 , VX 3 are compared to a trigger voltage VXL produced by the eleventh control block 36 . The output of the eighth, ninth, tenth control blocks 35 A, 35 B, 35 C are further conditioned by the seventh control block 34 resulting in the first and second phase buses BVA, BVB. The ‘link’ between the sixth control block 33 and the seventh control block 34 enables synchronization of the first and second control sections. [0076] In an effort to promote clarity, FIG. 12A illustrates some relevant signals generated by the three-phase controller 22 A. The first, second, and third regulation control voltages VR 1 , VR 2 , VR 3 are one hundred and twenty degrees out of phase with each other. Meanwhile, the phase voltages VA 1 , VA 2 , VA 3 are shifted in time with respect to each other the same amount as their corresponding regulation control voltages VR 1 , VR 2 , VR 3 are shifted in time with respect to each other. Furthermore, the second, fourth, and sixth phase voltages VB 1 , VB 2 , VB 3 are one hundred and eighty degrees out of phase with the first, third, and fifth phase voltages VA 1 , VA 2 , VA 3 , respectively. [0077] For example, if the frequency of the first, second, and third regulating circuits 16 A, 16 B, 16 C is one megahertz, then the rising and/or falling edges of the first, second, and third regulation control voltages VR 1 , VR 2 , VR 3 are separated by one-third of a microsecond. Consequently, the rising and/or falling edges of the first, third, and fifth phase voltages VA 1 , VA 2 , VA 3 are separated by one-third of a microsecond and the rising and/or falling edges of the second, fourth, and sixth phase voltages VB 1 , VB 2 , VB 3 are separated by one-third of a microsecond. [0078] With a few modifications to the three-phase controller 22 A, it is possible to further shift the first, third, and fifth phase voltages VA 1 , VA 2 , VA 3 by one or more whole periods of the regulating circuits 16 A- 16 C as illustrated in FIG. 12B . [0079] For example, if the frequency of each of the regulating circuits 16 A- 16 C is one megahertz, then the period of each of the regulating circuits 16 A- 16 C is one microsecond. Assuming a shift of one period, then the rising and/or falling edges of the first, third, and fifth phase voltages VA 1 , VA 2 , VA 3 are separated by one and one-third of a microsecond and the rising and/or falling edges of the second, fourth, and sixth phase voltages VB 1 , VB 2 , VB 3 are separated by one and one-third of a microsecond. Among other benefits, the more uniform spacing of the first intermediate voltage VX 1 ripple, the second intermediate voltage VX 2 ripple, and the third intermediate voltage VX 3 ripple reduces their effect on the output voltage VO. [0080] As in the single-phase case, the glitch capacitor CX can be removed altogether if the dead-time interval DT of each of the switched capacitor elements 12 A, 12 B, 12 C occurs when their corresponding regulating circuits 16 A, 16 B, 16 C are neither sinking nor sourcing current through an inductive element. For example, in a buck converter, the filter inductor is sinking current from the input only a portion of the time, whereas, in a boost converter, the filter inductor is sourcing current to the output only a portion of the time. These power converters have a discontinuous current interval during which current is either sunk or sourced. Therefore, the glitch capacitor CX is unnecessary if the dead-time interval DT of each of the switched capacitor elements 12 A, 12 B, 12 C occurs during the discontinuous input current interval. [0081] Both the controller 20 A in FIG. 4 and the three-phase controller 22 A in FIG. 11 utilize linear voltage-mode control. However, other control techniques such as non-linear voltage-mode control, peak current-mode control, and average current-mode control are applicable as well. [0082] The control circuitry described herein synchronizes the switched capacitor elements 12 A with the regulating circuits 16 A in the modular multi-stage power converter architecture. Among other advantages, the control circuitry described herein provides a way to minimize the effect of the intermediate voltage VX ripple on the output voltage VO and minimize the production of a voltage ‘glitch’ during the dead-time internal DT of the switched capacitor element 12 A. [0083] Various features, aspects, and embodiments of control techniques for power converters that utilize capacitors to transfer energy have been described herein. The features, aspects, and numerous embodiments described are susceptible to combination with one another as well as to variation and modification, as will be understood by those having ordinary skill in the art. The present disclosure should, therefore, be considered to encompass such combinations, variations, and modifications. Additionally, the terms and expression which have been employed herein are used as terms to description and not of limitation, and there is no intention, in the use of such terms and expression, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims are intended to cover all such equivalents.	An apparatus for power conversion comprises a voltage transformation element, a regulating element, and a controller; wherein, a period of the voltage transformation element is equal to a product of a coefficient and a period of the regulating circuit, and wherein the coefficient is selected from a group consisting of a positive integer and a reciprocal of said integer.	7
BACKGROUND OF THE INVENTION (1) Field of the Invention This invention relates to improvements in pneumatic percussion hammers. (2) Prior Art The specification of my Australian Patent Application No. 81767/87 describes and illustrates a pneumatic percussion hammer having a tubular casing with a top sub to receive air under pressure from the outer tube of a double tube drill stem, and with a bit having an anvil head slidable in a bottom sub of the casing. An axial air feed tube directs air under pressure through the bit and air passages therethrough and a piston slidable on a central air outflow tube is caused to reciprocate by air under pressure directed through an arrangement of air passages and chambers to strike the anvil in a rapid succession of blows which are transmitted to the bit for rock drilling. These hammers have proved to be very successful, and the present invention has been devised with the general object of adding certain improvements which will broaden the versatility and range of applications of the hammer, as well as facilitating its repair and maintenance. SUMMARY OF THE PRESENT INVENTION Accordingly, the invention resides broadly in a pneumatic percussion hammer including: a tubular casing, a top sub connected to the top of the casing and adapted to receive air under pressure from the outer tube of a double tube drill stem, a bottom sub connected to the housing, an air feed tube disposed coaxially in the casing to conduct air under pressure by way of non-return valve means from the top sub into the casing, an air outflow tube disposed coaxially within the casing and through the air feed tube means for connecting the air outflow tube to the inner tube of the double tube drill stem, a bit slidable in the bottom sub, having a shank axially apertured for slidable engagement on the air outflow tube and with an anvil at its head, an axially apertured piston slidable on the air outflow tube and at its upper part slidable on the air feed tube, and air passages and ports in the piston and chambers in the inner wall of the casing so to direct air under pressure from the air feed tube as to cause the piston to reciprocate to strike the anvil on its downstroke and to exhaust through passages in the bit leading to the bottom of the air outflow tube, the air outflow tube being slidably removable through the top sub. Other features of the invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention is shown in the accompanying drawings, wherein: FIG. 1 is a sectional view of the upper part of a pneumatic percussion hammer according to the invention, FIG. 1a is a sectional view of the lower part of a pneumatic percussion hammer according to the invention, FIG. 2 is a sectional view, to larger scale, of the upper part of the pneumatic percussion hammer shown in FIG. 1, with its adaptor unscrewed and with its air outflow tube partly withdrawn, FIG. 3 is a sectioned view to the same scale as FIG. 2 of the upper part of the pneumatic percussion hammer, the air outflow tube shown in FIGS. 1, 1a, and 2 being replaced with one of modified type, and FIG. 4 is a sectioned view to the same scale as FIGS. 2 and 3 of the upper part of the hammer fitted with a modified replacement for the air outflow tubes of the other figures, FIG. 4a is a sectional view to the same scale as FIGS. 2 and 3 of the lower part of the hammer fitted with a modified replacement for the air outflow tubes of the other figures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The percussion hammer illustrated in FIGS. 1, 1a, and 2, to which reference is initially made, includes a cylindrical tubular casing 10, of which each end part of the bore is enlarged and threaded. Two further enlargements of the bore define a top pressure chamber 11 and a bottom pressure chamber 12, and a central bore enlargement defines a central chamber 13. The lesser diameter parts between these chambers comprise a top shoulder 14, a bottom shoulder 15 and top and bottom piston bearings 16 and 17. A piston stop ring 18 is seated on, and within, the top shoulder 14 and has a seating for the enlarged or flanged top of an air feed tube 19 located coaxially within the casing 10 and held in place by a bottom flange 20 of an axially bored air inlet fitting 21. This fitting 21 is held in place by a top sub 22 screwed into the threaded upper end of the casing 10, its lower end bearing on an annular seal 23 on the base flange 20 of the air inlet fitting 21. An air outflow tube 24 passes through and is sealed in the air inlet fitting 21 and passes coaxially through the hammer, its enlarged or flanged top seating on the top of the air inlet fitting. The air outflow tube 24 is releasably held in place by an adaptor 25 screwed onto the threaded upper part of the air inlet fitting. The adaptor has a pair of opposed lugs 26 so that, by using a suitable tool it may be easily unscrewed to enable the air outflow tube 24 to be slidably withdrawn from the hammer, as indicated in FIG. 2. The top sub 22 and the adaptor 25 may be engaged by a conventional double-tube drill stem (not shown) of a rock drilling assembly, the outer or air inflow tube being screwed into the top sub 22 in usual manner, the central air outflow tube engaging in the adaptor 25. Air passing under pressure down the outer tube of the drill stem passes, against the action of a spring-loaded annular check valve 27 on the air inlet fitting 21, through air passages 28 in the lower part of this fitting into the top of the air feed tube 19. A piston 29 is slidable in the top and bottom piston bearings 16 and 17 and is axially bored, with a diameter reduction or annular shoulder 30 within the bore. This shoulder 30 divides the piston bore into an upper axial passage 31 and a lower axial passage 32 and fits closely but slidably about the air outflow tube 24. The top part of the upper axial passage 31 receives closely but slidably the air feed tube 19. A bit 33 has its shank 34 slidably engaged in a driver sub 35 which is screwed into the threaded lower part of the casing 10 and thus holds a split anvil stop ring 36 in place against the bottom shoulder 15, this stop ring limiting the downward movement of the enlarged upper end or anvil 37 of the bit shank 34. The lower part of the bit shank is formed with splines for slidable but non-rotatable movement in corresponding grooves 38 in the bore of the driver sub 35. A slidable seal tube 39 has its lower end fixed in the top of an .air passage 40 which is formed axially through the bit shank 34. This passage 40 communicates with oblique air ducts 41 leading into flutes 42 formed in the sides of the bit and leading into channels 43 in the bottom of the bit leading in turn to ducts 44 leading convergently upwards to the bottom of the air outflow tube 24, the lower part of which is engaged closely but slidably in the reduced-diameter lower part of the air passage 40. When the piston 29 is raised so that its top is close to the stop ring 18, air under pressure from the air feed tube 19 enters the upper axial passage 31 of the piston and thence passes through an oblique pressure port 45 into the top pressure chamber 11 to drive the piston down onto the anvil 37, as shown in FIGS. 1 and 1a causing the bit to be driven onto the work face. A top exhaust port 46 in the piston then connects the top pressure chamber 11 to the central chamber 13, so that air under pressure flows into the central chamber and thence, through a central chamber exhaust port 47 in the piston to the piston's lower axial passage 32, through the sliding seal tube 39 and the axial passage 40 of the bit shank and through the bit air ducts 41, flutes 42, channels 43, ducts 44 and up through the air outflow tube 24. When the piston 29 has been driven down onto the anvil 37 as described, air under pressure in the upper axial passage 31 of the piston is conducted through a pressure port 48 in the piston to the bottom pressure chamber 12 to drive the piston upwards until the port 48 is closed upon entering the lower piston bearing 17. The piston rises clear of the sliding seal tube 39 and air under pressure in the bottom pressure chamber 12 expands into the lower axial passage 32 of the piston and thence through the central chamber exhaust port 47 to the central chamber 13. With the upstroke of the piston, air is compressed between it and the piston stop ring 18 to absorb shock and impart reaction air thrust to cause the piston to commence its next downstroke. While the hammer operates the rock fragments produced are carried up through the hammer in a strong up-flow of air and are brought to ground level through the double tube drill stem without contamination from higher levels of the drilled hole. As soon as the casing 10 is lifted to bring the bit clear of the work face, the bit drops relative to the raised casing until the anvil rests on the anvil stop ring 36, the piston coming to rest on the anvil, the hammer then being in a condition of air balance. As soon as the casing is lowered to bring the bit onto the work face, the hammer will be brought into operation again. The air outflow tube 24 is subject to considerable wear and is likely to require replacement from time to time. In pneumatic percussion hammers previously made the removal of an air outflow tube has required the prior removal of the top sub and other parts of the hammer. According to the present invention, it is necessary only to unscrew the adaptor 25 after which the air outflow tube 24 may be easily withdrawn, as indicated in FIG. 2. The quick and easy removal of the air outflow tube 24 permits its replacement, as may from time to time be required, with tubes of modified character to enable the operation of the hammer to be varied to suit particular drilling requirements. Such a modification is shown in FIG. 3, in which the air outflow tube 24 has been replaced by a capped tube 50 of which the upper end is closed by a cap or plug 51, the tube being formed with apertures 52 which are located below the piston stop ring 18 when the tube is installed. The operation of the pneumatic percussion hammer, in this embodiment, is generally similar to that before described except in that the air introduced to the hammer under pressure from the drill stem passes, as before described, through the oblique air ducts 41 of the bit to the flutes 42, and also by way of the air feed tube 19 and the apertures 52 into the capped tube 50 and thence through the bit ducts 44 to the flutes 42 and the bottom of the bit. The hammer, in this mode, is no longer of reverse circulating type, but operates to carry all of the rock fragments up the outside of the hammer. A further, ,modification of the invention is shown in FIGS. 4 and 4a which the air outflow tube 24 shown in FIGS. 1, 1a and 2 is replaced by a modified air outflow tube 53 having a reduced external diameter section 54 which may be varied in length and in location. When the reduced diameter section 54 is as shown in the drawings, of a length and location indicated as "a", clearance remains at all times during the operation of the hammer between the shoulder 30 within the bore of the piston 29 and the air outflow tube 24. Consequently additional air under pressure will be expelled down through the air passage 40 through the bit shank 34 and by way of the air ducts 41 to the flutes 42 formed in the sides of the bit 33. The bit therefore has about it an amplified shroud of air under pressure. This is found to have very considerable advantages in certain circumstances such as when the percussion hammer has passed through a water-bearing stratum, the pressure of air preventing or greatly reducing ingress of water to the air outflow tube. Therefore even though the hammer is worked through water bearing levels, dry rock chips only will be brought up through the hammer. If the reduced diameter section 54 instead extends for the distance indicated by "b" in FIG. 4, the extra air under pressure will be fed to the flutes 42 of the bit only when the bit descends suddenly to full extent, as may happen, for example, on encountering a stratum of sand, offering little resistance to the hammer. The extra air under pressure will act to impel the sand up through the air outflow tube 24. If the reduced diameter section 54 should be located as indicated at "c", then air under pressure will pass to the bit when the hammer is lifted so that the bit drops fully relative to the hammer, and the operation of the hammer ceases. The air under pressure will assist in flushing out the hole.	A pneumatic percussion hammer for attachment to a drill tube is coaxially constructed about an outflow tube which is mounted therein for axial removal and replacement when worn. A cylindrical piston moves axially between a top sub wherein a drill stem is screwed, and an anvil of a bit at the bottom. A casing and the piston are configured to valve the flow of pressurized air therethrough for reciprocating motion of the piston and an outflow that carries debris through the outflow tube and drill stem.	4
CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit, under 35 U.S.C. § 365 of International Application PCT/US03/37768, filed Nov. 26, 2003, which was published in accordance with PCT Article 21(2) on Jun. 17, 2004 in English and which claims the benefit of U.S. provisional patent application No. 60/430,818, filed Dec. 4, 2002. FIELD OF THE INVENTION The invention relates to a light valve system and, more particularly, to a light valve system with a microdisplay for use in a rear projection television. BACKGROUND OF THE INVENTION In a conventional light valve system for, example in displays such as, rear projection televisions (RPTVs), digital cinema, etc., white light output from a lamp is directed to a microdisplay such as a liquid crystal display (LCD), liquid crystal on silicon (LCOS), or digital light processing (DLP) system, through a series of integrating and collimating optics. In the LCD or LCOS systems, white light is separated into its component red, green, and blue (RGB) bands of light, polarized by a polarizing beam splitter (PBS) in the case of LCOS, and directed onto the microdisplay. The microdisplay has a matrix of pixels. The microdisplay operates to modulate each of the pixels of the component RGB bands of incident light by a gray-scale factor control output from a controller based on a video input signal to form a light matrix of discrete modulated light signals or pixels. The light matrix is reflected or output from the microdisplay and directed to a system of projection lenses that projects the modulated light onto a display screen, combining the pixels of light to form a video image. In the DLP system, the white light is separated into its component RGB bands of light, and reflected onto a DLP microdisplay. The microdisplay is a semiconductor device containing an array of hinge-mounted microscopic mirrors. Each of the mirrors corresponds to one pixel in a video image input to the microdisplay. When the semiconductor is driven by the video input signal, the mirrors are tilted or switched on and off to reflect all or some of the incident light. The array of pixels reflected from the mirrors form a light matrix corresponding to the video-input signal. The light matrix is reflected or output from the microdisplay and directed to a projection lens system that projects the modulated light onto a display screen to form a video image. A disadvantage of these display systems is that the video images projected in a dark state scene are inferior in quality to the video images that are projected in a bright state scene. In the LCD or LCOS systems, the difference in quality occurs because the amount of light directed onto the microdisplay remains constant regardless of the brightness of the video image input to the microdisplay. Gray-scale variation from pixel to pixel is thereby limited by the number of bits used to process the video-input signal. Because the video input signal is a fixed number of bits, which corresponds to the full scale of light, there tend to be very few bits available for subtle differences in darker areas of the video image. For example, if the microdisplay is capable of reproducing 1024 gray shades (10-bit output digital to analog converter (DAC)) when the program contains only 0 to 64 gray shades, the net effect is that contrast appears poor and the video image appears to have a severe level of noise and contouring due to quantization effects and truncation effects. The DLP system suffers from more severe contouring effects than the LCOS or LCD systems due to the intrinsically linear response of the semiconductor. To alleviate the differences in quality occurring between the light and dark video images, it is known to increase the contrast of the microdisplay itself. Increasing the contrast of the microdisplay, however, leads to very high data rates, very high resolution DAC's, and very critical optical and liquid crystal performance requirements. It is, therefore, desirable to develop a light valve system that enhances the contrast ratio for the video images, particularly in dark video images, and reduces contouring artifacts. SUMMARY OF THE INVENTION The invention relates to a light valve system that comprises a color selection device configured to temporally attenuate component color bands of light to correspond with a video input signal. A first polarizing beam splitter configured to polarize the component color bands into oppositely polarized components, and a microdisplay configured to receive at least one of the oppositely polarized components for forming a projected light matrix. The invention further relates to a light valve system that comprises a color selection device configured to temporally separate light into its component color bands to correspond with a video input signal. A first polarizing beam splitter configured to polarize the component color bands into a first set of oppositely polarized components. First and second liquid crystal displays. Each of the first and second liquid crystal displays configured to receive one of the first set of oppositely polarized components for forming first and second light matrices, respectively. A second polarizing beam splitter configured to receive the first and second light matrices for separating the first and second light matrices into a second set of oppositely polarized components, and a microdisplay configured to receive at least one of the second set of oppositely polarized components for forming a projected light matrix. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in greater detail with reference to the following figures, wherein: FIG. 1 is block diagram of a light valve system according to a first embodiment of the invention; FIG. 2 is block diagram of a light valve system according to a second embodiment of the invention; and FIG. 3 is a schematic diagram of a polarizing beam splitter arrangement for use in the system of FIG. 2 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a light valve system 1 according to a first embodiment of the invention. The system 1 includes a lamp 10 . The lamp 10 generates white light 4 and projects the white light 4 toward a set of illumination optics 11 . The illumination optics 11 may include, for example, a polarizer and/or an integrator. In this embodiment a polarizer is included to rotate incident light to an s-polarization. The illumination optics 11 directs a telecentric beam of the white s-polarized light 4 toward a color selection device 5 . In the illustrated embodiment, the color selection device 5 is a color switching device, which is an optical device having several layers of liquid crystal displays stacked together. Examples of such a color selection device 5 include the COLORSWITCH® made by ColorLink, Inc. of Boulder, Colo. and the Application Specific Integrated Lens (ASIL) made by DigiLens, Inc. of Sunnyvale, Calif. The white light 4 enters the color selection device 5 , and the color selection device 5 temporally filters the white light 4 incident thereon into sequential component red, green, and blue (RGB) bands of light 12 . A selected band of light is transmitted or reflected depending on a digital control signal voltage applied to the color selection device by a display controller 3 . The color selection device 5 also has an on/off state voltage input for receiving a control signal from the display controller 3 . When the voltage level from the display controller 3 is high, it drives the color selection device 5 to an off state and when the voltage level from the display controller 3 is low, it drives the color selection device 5 to an on state in which light is transmitted therethrough. The display controller 3 , by virtue of its processing of the video-input signal to the microdisplay 7 , performs analysis on the video signal to determine its content. In this analysis, the display controller 3 analyzes the video-input signal on a pixel-by-pixel basis for the frame to be displayed. If none of the pixel input values exceed half of full scale, then the voltage level controlling attenuation in the color selection device 5 is set at 50% of full scale. If on the other hand the input pixel values are all zero thus indicating a full black screen, the voltage level controlling a color selection device is reduced to the full on state voltage. This attenuation control enhances contrast especially in frames containing mostly dark content. Since ultimate contrast is the product of contrast achieved through the optical components in the system, if for example the color selection device 5 has a contrast of 50:1 and the microdisplay 7 has a contrast of 600:1 then the measured sequential contrast is 30000:1 allowing for improved contrast levels especially in the dark state. The display controller 3 is programmed with the transfer function of the microdisplay 7 . To program the display controller 3 the microdisplay 7 may be calibrated at a factory level or auto-calibrated by photosensors in a cabinet or a projection light path, e.g., behind a folding mirror. Because the calibration may be performed in binary steps, the calibration would take no more than a few seconds and may be performed during normal operation after the video-input signal is known. As a result, the dynamic contrast of the system 1 is improved without the cost of any additional hardware, and a customer has the option of reducing the peak brightness of the video image as she chooses without producing undesired contouring effects. The sequential component RGB bands of light 12 exit the color selection device 5 and are directed toward a polarizing beam splitter 8 (PBS). Incident s-polarized components 19 of the incident light 12 are reflected from the polarizing surface 17 to a third surface 15 . A microdisplay 7 is disposed beyond the third surface 15 of the PBS 8 , and the s-polarized component 19 of the light 12 is incident thereon. In the illustrated embodiment, the microdisplay 7 is a liquid crystal on silicon (LCOS) imager. Alternatively, a liquid crystal display (LCD) may be used and the optical system adjusted accordingly. The LCOS microdisplay 7 serves to modulate incident light with video signal coming from the display controller 3 . Each of the pixels of the projected light matrix 18 has an intensity or luminance proportional to the individual gray scale value provided for that pixel in the microdisplay 7 . As a result of the modulation, the LCOS microdisplay 7 reflects a light matrix 18 comprising a matrix of pixels or discreet dots of p-polarized light back through the third surface 15 of the PBS 8 . The p-polarized components of the projected light matrix 18 pass through the polarizing surface 17 and out of the PBS 8 through a fourth surface 16 . The projected light matrix 18 is directed from the fourth surface 16 to a projection lens system 9 . The projection lens system 9 projects the light matrix 18 onto a display screen 6 , combining the pixels of light to form the video image corresponding to the video input signal 2 . FIG. 2 shows a light valve system 20 according to a second embodiment of the invention. The system 20 includes a lamp 35 . The lamp 35 generates white light 23 and projects the white light 23 toward illumination optics 31 . The illumination optics 31 may include, for example, an integrator, such as, a sequential color recapture (SCR) integrator. The integrator 31 directs a telecentric beam of the white light 23 toward a color selection device 24 . In the illustrated embodiment, the color selection device 24 is a color wheel, which has a disc with fan-shaped sectors uniformly disposed along a circumference of the disk. The sectors filter the white light 23 incident thereon into its component RGB bands of light 25 in a timed sequence corresponding to color wheel rotation. The color selection device 24 is rotated by a motor (not shown) and is controlled by a display controller 22 to transmit corresponding component RGB bands of light 25 in synchronization with a video input signal 21 to transmit the respective component RGB bands of light 25 on a frame-by-frame basis. The component RGB bands of light 25 are directed toward a PBS arrangement 50 . The PBS arrangement 50 includes first and second PBSs 46 , 49 , first and second mirror prisms 47 , 48 , and first and second LCDs 26 , 28 . Alternatively, the first and second LCDs 26 , 28 may be arranged before the integrator 31 . As shown in FIG. 3 , the component RGB bands of light 25 enter a first face 42 of the first PBS 46 and are polarized by a first polarizing surface 43 to have an s-polarized component 27 and a p-polarized component 45 . The path of the s-polarized component 27 of the RGB bands of light 25 through the PBS arrangement 50 will first be described in greater detail, and then, the path of the p-polarized 45 component will be described in greater detail. The s-polarized component 27 is reflected through a second face 56 of the first PBS 46 and is received in the first mirror prism 47 . The s-polarized component 27 is reflected by a first mirror surface 59 out of the first mirror prism 47 and toward the first LCD 26 . The first LCD 26 is for example, a single cell panel containing a matrix of liquid cells coupled to an electrical signal from the display controller 22 . The electrical signal controls the LCD 26 to have it either rotate polarization of light passing therethrough or pass the light without rotation. As a result the first LCD 26 transmits a first light matrix 38 comprising a matrix of pixels or discreet dots of light with s-polarized and p-polarized components. The first light matrix 38 enters a first face 44 of the second PBS 49 and is polarized by a second polarizing surface 53 . The s-polarized component (not shown) of the first light matrix 38 is reflected through a second face 57 of the second PBS 49 and is discarded while, the p-polarized component 60 of the first light matrix 38 passes through the second polarizing surface 53 and out of the second PBS 49 through a third face 52 toward illumination lens 33 . The p-polarized component 45 of the component RGB band of light 25 passes through the first polarizing surface 43 and through a third face 51 of the first PBS 46 toward the second LCD 28 . The second LCD 28 is identical to the first LCD 26 in structure and function and, as such, further description thereof has been omitted. The second LCD 26 transmits a second light matrix 55 comprising a matrix of pixels or discreet dots of light with s-polarized and p-polarized components. The second light matrix 55 enters the second mirror prism 48 and is reflected by a second mirror surface 58 out of the second mirror prism 48 and toward the second PBS 49 . The second light matrix 55 enters a fourth face 54 of the second PBS 49 and is polarized by the second polarizing surface 53 . The p-polarized component (not shown) of the second light matrix 55 passes through the second polarizing surface 53 and is discolored through second face 57 of the second PBS 49 . The s-polarized component 61 of the second light matrix 55 is reflected out of the second PBS 49 through the third face 52 and is received in a light stop (not shown) in combination with the s-polarized component 45 , so that there is a fairly low loss of total brightness. As shown in FIG. 2 , the s-polarized component 61 of the second light matrix 55 and the p-polarized component 60 of the first light matrix 38 are simultaneously focused by illumination lenses 33 into a third mirror prism 34 for high-through-put efficiency. The third mirror prism 34 may be, for example, a total internal reflection (TIR) prism or off axis optics. The s-polarized component 61 of the second light matrix 55 and the p-polarized component 60 of the first light matrix 38 pass through a first surface 36 of the third mirror prism 34 . The s-polarized component 61 of the second light matrix 55 and the p-polarized component 60 of the first light matrix 38 are reflected at an angle away from a reflection surface 41 of the third mirror prism 34 and through a third surface 37 the third mirror prism 34 . A DLP microdisplay 30 is disposed beyond the third surface 37 of the mirror prism 37 , and the combined s-polarized and p-polarized components 60 , 61 are incident thereon. The DLP microdisplay 30 may be any suitable digital light processor (DLP), such as the DLP made by Texas Instruments Incorporated of Dallas, Tex. The microdisplay 30 has an optical semiconductor (not shown), such as the DIGITAL MICROMIRROR DEVICE made by Texas Instruments Incorporated of Dallas, Tex. The semiconductor contains an array of hinge-mounted microscopic mirrors. Each of the mirrors corresponds to one pixel in a video image (not shown) of the video-input signal 21 . When the semiconductor is driven by the controller 22 based on video input signal 21 , the mirrors are tilted or switched on or off to reflect all or some of the first and second light matrices 51 , 49 . The array of pixels reflected from the switched mirrors forms a projected light matrix 40 corresponding to the video-input signal 21 from the display controller 22 . Operation of the LED's 26 , 28 serve as attenuation control whereby some p-polarized and some s-polarized light is discarded before recombination. For example, as described above in the first embodiment if none of the video input pixel values exceeds half of full-scale, then the first and second LCDs 26 , 28 control fifty percent of incident light. In an instance where the video input signal 21 indicates a full black screen, the first and second LCDs 26 , 28 are set by the display controller 22 to maximum, and the microdisplay 30 is driven with zeros to achieve very high sequential contrast. Thus, if the first and second LCD's 26 , 28 have a peak attenuation of 50:1, and the microdisplay 30 has a sequential contrast of at least 600:1, then the measured sequential contrast is 30,000:1. The projected light matrix 40 is reflected from the microdisplay 30 back through the third surface 37 of the TIR prism 34 . The projected light matrix 40 passes through the reflecting surface 41 of the TIR prism 34 and out of the TIR prism 34 through a fourth surface 39 . The projected light matrix 40 is directed from the fourth surface 39 to a system of projection lenses 32 . The projection lenses 32 project the projected light matrix 40 onto a display screen 29 , to form the video image corresponding to the video input signal 21 . The system 20 has the benefit of allowing the microdisplay 30 to be illuminated with alternating polarizations of light, which allows for polarization-based stereographic imaging. The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.	The invention relates to a light valve system that enhances the contrast ratio for light and dark video images and reduces contouring artifacts. The light valve system comprises a color selection device configured to temporally attenuate component color bands of light to correspond with a video input signal. A first polarizing beam splitter configured to polarize the component color bands into oppositely polarized components, and a microdisplay configured to receive at least one of the oppositely polarized components for forming a projected light matrix.	7
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/578,656, filed Dec. 21, 2011, which is incorporated by reference herein in its entirety. BACKGROUND [0002] 1. Field of the Invention [0003] The present invention relates to semiconductor chip manufacturing. More particularly, the present invention relates to accommodating defects in the logical structure of semiconductor chips. [0004] 2. Background Art [0005] Defect tolerances can be a critically important consideration in the manufacture of semiconductor chips. These considerations impact performance, yield, and ultimately cost. Thus, an important goal in the semiconductor manufacturing process is to minimize the occurrence of chip defects and reduce the impact of any defects that occur. [0006] Traditional semiconductor manufacturing techniques typically result in the production of a predictable percentage of chips with defects. These defects occur because inherent impurities, such as dust or other particles, contaminate wafers that are used to form the chip during manufacturing. Unfortunately, the introduction of these inherent impurities can never be completely prevented. Consequently, most semiconductor wafer lots will include a small percentage of chips with inherent defects. [0007] Depending on the ultimate function of the chip, some defects can be tolerated depending upon the number and nature of the defects. However, these defects become more problematic when they occur in devices that perform critical processing functions, such as math computations. For example, a single defect occurring in a particular module of some devices will render the device inoperable. Defects occurring in other modules, within that same device, may not necessarily render the entire device inoperable. Therefore, these latter defects could be tolerated within the device, on some scale. [0008] The single instruction multiple data (SIMD) device (module), as understood by those of skill in the art, is a multi-processor architecture in which multiple processors—e.g. processing elements—perform the same operation on multiple data simultaneously. SIMDs are considered to be the computational workhorses, for example, of graphics processing devices. Conventional SIMDs are designed to include a small number of redundant sub-modules in anticipation of manufacturing defects that might occur in other modules. After manufacture, these SIMDs are evaluated to determine the nature and number of manufacturing defects. If the nature and number of defects are below a certain threshold, the device can be still be used, albeit, at perhaps a degraded level of performance. On the other hand, if the nature and number of defects exceeds the threshold, the device is considered unusable. BRIEF SUMMARY OF EMBODIMENTS [0009] What are needed, therefore, are methods and systems to more efficiently test, identify, and compensate for manufacturing defects in logic devices, such as SIMDs. [0010] Embodiments of the present invention, in certain circumstances, provide an apparatus including a scheduler and a plurality of logic devices coupled to the scheduler, each including a defect indicator. The scheduler determines whether one or more of the logic devices is defective based upon its respective defect indicator. [0011] Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES [0012] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. Various embodiments of the present invention are described below with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. [0013] FIG. 1 is an illustration of an exemplary wafer constructed in accordance with an embodiment of the present invention; [0014] FIG. 2 is an exemplary illustration of a modeling layout of the logic structure of an individual IC die in accordance with an embodiment of the present invention; [0015] FIG. 3 is a more detailed view of logic areas within the IC illustrated in FIG. 2 ; [0016] FIG. 4 is an exemplary illustration of an IC modeling of approach in accordance with an embodiment of the present invention; [0017] FIG. 5 is a block diagram illustration of defect tolerance methodology used in accordance with embodiments of the present invention; [0018] FIG. 6 is an illustration of an exemplary defect tolerant design constructed in accordance with an embodiment of the present invention; [0019] FIG. 7 is an exemplary illustration of a render-back SIMD arrangement in accordance with an embodiment of the present invention; [0020] FIG. 8 is an illustration of exemplary test methodology performed in accordance with an embodiment of the present invention; and [0021] FIG. 9 is an illustration of exemplary test equipment constructed and arranged in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS [0022] In the detailed description that follows, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. [0023] The term “embodiments of the invention” does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation. Alternate embodiments may be devised without departing from the scope of the invention, and well-known elements of the invention may not be described in detail or may be omitted so as not to obscure the relevant details of the invention. In addition, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. For example, as used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. [0024] FIG. 1 is an exemplary layout arrangement 100 of a silicon wafer 102 . Wafer 102 includes a plurality of sections 104 , each representing an IC die, such as IC die 106 . In embodiments of the present invention, a single wafer, such as wafer 102 , can produce different qualities of dies that can be used across different product segments. A top-quality (higher quality) product, for example, would use those IC dies with the fewest number of defects. A representative top-quality product, for example, could be a desktop computer or the like. [0025] IC dies that experience a higher number of defects during design and manufacturing, though still usable, may be suitable for use in a lower performance or differently performing product. A representative lower performance product, for example, could be a low end notebook computer. The higher the quality of the individual IC dies within the wafer, the faster those ICs will typically be. The speed of an IC is generally strongly correlated to of the number of compute units provided therein. By way of example, a compute unit can include one or more SIMDs. Faster ICs, those with the fewest defects, are typically more suitable for use in the higher performing (sometimes referred to in the industry as higher quality) products. [0026] FIG. 2 is an exemplary illustration of a modeling layout 200 of the logic structure of an individual IC die, such as the IC die 106 . In FIG. 2 , the modeling layout 200 includes a memory area 202 , a redundant logic area 204 , and a non-redundant logic area 206 . The internal structure of the memory area 202 , the redundant logic area 204 , and the non-redundant logic area 206 , will be explained in greater detail below. [0027] The term redundant, as used herein, represents the incorporation or use of additional or different logic units in the design of an IC so that the function of the IC is not strongly impaired due to the occurrence of one or more defective logic units. In other words, although one or more individual logic units may be defective, the entire IC is not rendered inoperable. Stated another way, there is a predetermined level of defect tolerance (redundant logic area 204 ) built into the IC. This defect tolerance enables the IC to still perform, albeit at a sub-optimal level. This defect tolerance is provided within the redundant logic area 204 . [0028] However, if a defect occurs in the non-redundant logic area 206 , the IC is rendered completely inoperable. A more detailed illustration of the modeling layout 200 is illustrated in FIG. 3 . [0029] In the exemplary illustration of FIG. 3 , the redundant logic area 204 of the IC die 106 includes a repairable area cores 301 and 302 . Each of the cores 301 and 302 is further subdivided into a number of horizontal rows, each representative of an individual SIMD, such as SIMDs 304 ( a ), 304 ( b ), and 312 ( a ). In FIG. 3 , an expanded view of SIMD 312 ( a ) is provided. [0030] SIMD 312 ( a ) includes, for example, a logical data structure (LDS) unit 314 , along with arithmetic (A) units, such as units 316 . Also as illustrated, SIMD 312 ( a ) is further subdivided into logic areas and memory areas. [0031] Redundancy, or defect tolerance, is a function of an analysis of the logic units within the IC to determine which units can be repeated, and how many times, during manufacturing. These repeated units are representative of the built-in defect tolerance, noted above. If any of the logic units within the defect tolerant area (redundant logic) fails, the entire IC is not rendered inoperable since the logic unit was repeated many times. If failures occur in the redundant logic areas of the IC, although the IC can still be used, it is simply used in products with a lower quality profile. [0032] FIG. 4 is an exemplary illustration of a modeling approach 400 constructed in accordance with an embodiment of the present invention. In FIG. 4 , a device such as IC die 106 is modeled and placed under test. In the embodiments, testing occurs in accordance with specific test methodology, such as test methodology 401 . [0033] In the exemplary illustration of FIG. 4 , test methodology 401 includes a scan pattern analysis 402 and use of a redundancy technique 403 , each described in greater detail below. During an actual test, test methodology 401 is performed on a device, such as IC die 106 , using an automated test equipment (ATE) mechanism 404 . By way of example, during testing, redundant logic area 204 and non-redundant logic area 206 , shown in FIG. 2 , are further modeled. More specifically, redundant logic area 204 is further modeled to expose a redundant scan chain section 406 . Non-redundant logic area 206 is further modeled to expose a “must work” scan chain section 412 . As used herein, the term “must work” conveys that if a single scan chain (logic device) within section 412 fails, IC die 106 will be rendered completely inoperable. [0034] In FIG. 4 , a redundant scan chain section 406 includes individual SIMDs within IC die 106 divided into their most basic electrical circuit elements (i.e., flip flops). For example, SIMD 304 ( a ) of FIG. 3 is modeled (characterized) to produce redundant scan chain 406 ( a ), shown as individual flip-flops connected to form a chain, along with redundant scan chain 406 ( b ). Also shown in FIG. 4 is must work scan chain section 412 . Must work scan chain section 412 , among other scan chains not labeled, includes scan chain 412 ( a ). By way of example, scan chain 412 ( a ) corresponds to SIMD 312 ( a ) of FIG. 3 . [0035] In the embodiments, the remainder of IC die 106 can be analyzed with its logic being classified as “must work” or “can be allowed to fail.” A fuse box 414 , illustrated in greater detail below, is used in a multiplexer configuration to facilitate testing, identification, and isolation of specific defective scan chains. [0036] By way of example, after a test has been performed in accordance with test methodology 401 , a user will know whether a defect has occurred in the “must work” part of the IC die 106 . Consequently, the user will know if the defect has rendered the device inoperable. This principle is known as “stop and fail.” If a defect occurs in the “can be allowed to fail” category, these defects can be accumulated under a principle known as “continue and fail.” The inventor of the subject matter of the present application has noted during testing that the stop and fail category typically represents about 5% of a given IC die design. The continue and fail category typically represents about 95% of the IC die design. [0037] The benefit of the foregoing technique is that once test methodology 401 has been performed, the user will know to what extent if at all, a particular IC die such as IC die, such as IC die 106 , can be used if it includes defective SIMDs. This knowledge can ultimately increase IC die manufacturing efficiency and facilitate more realistic pricing models. [0038] In an exemplary embodiment of the present invention, test methodology 401 , ATE 404 , and fuse box 414 cooperatively operate to facilitate a more efficient and secure IC design. In the embodiment, IC chips are designed to include e-fuses burned into the chip such that during subsequent activations, it's known that particular SIMDs are bad. This is also a fail-safe mechanism, preventing the use of devices with defect specifications that exceed approved levels. This technique also enhances security by reducing cyber threats—preventing a computer hacker, for example, writing into particular IC chip registers and causing malfeasance. [0039] Thus, in the illustration 400 of FIG. 4 , arrow 416 is representative of a mechanism for testing the IC die and the embedded e-fuse. More specifically, fuse box 414 includes special pins 418 to facilitate identification of defective SIMDs during testing. The special pins 418 also enable special programming that helps compensates for any identified defective SIMDs. [0040] In an embodiment of the present invention, a flexible scheme is provided for IC design and testing to: (a) determine whether defective SIMDs are present, (b) if defective SIMDs exist, to identify their location; (c) classify whether the defective SIMDs are redundant SIMDs or must work SIMDs, and testing the SIMDs based on this knowledge; and (d) facilitating the proper adjustments in reconfiguring the IC die based upon the defective SIMDs. [0041] FIG. 5 is a high level illustration 500 of various aspects of the embodiments of the present invention. More particularly, FIG. 5 depicts that defect tolerance techniques are provided throughout multiple stages of IC device development. As described and illustrated herein, embodiments of the present invention include aspects of defect tolerance considerations that occur at the register transfer level (RTL) phase 502 of IC chip design. Embodiments also include techniques, such as the defect tolerance techniques noted above, that occur during gate level design phase 504 of IC chip design. Further embodiments of the present invention include defect tolerance considerations that occur during an automated testing phase 506 , and are facilitated through use of various ATE configurations. Each of the phases 502 , 504 , and 506 , need not be performed in their entirety in the order they appear in FIG. 5 . Greater details of each of these stages are provided below. [0042] FIG. 6 is an illustration of an exemplary embodiment of the present invention, including an arrangement 600 designed into the render backend of an IC die. Arrangement 600 is provided to facilitate IC defect tolerant principles in accordance with the present invention. As illustrated in FIG. 6 , arrangement 600 includes a scheduler 602 for scheduling work items 604 for processing within a pipeline of a graphics processing unit (GPU), not shown. Scheduler 602 can be formed from standard GPU pipeline components, such as a shader processor input (SPI). By way of example, a GPU constructed in accordance with the present invention includes a number of SIMDs, such as SIMD group 606 . SIMD group 606 includes SIMD 0 to SIMD N. Arrangement 600 also includes a multiplexing device 608 to facilitate identification and switching in/out defective SIMDs from SIMD group 606 . [0043] In one embodiment of arrangement 600 illustrated in FIG. 6 , one or more spare SIMDs are provided during design that can be swapped out with later identified defective SIMDs, as is more clearly illustrated in FIG. 7 . [0044] FIG. 7 is an exemplary illustration of an embodiment of the present invention implementing render-backend redundancy. In FIG. 7 , for example. SIMI) group 606 of FIG. 6 can include one or more redundant SIMDs, such as SIMD (X). SIMD (X), or any other redundant SIMD, is multiplexed (i.e., swapped in) and activated only when one or more of operational SIMDs 0 -N is identified as being defective. With render-back end, instead of allowing an IC device to continue to operate with a failed logic component, such as a defective SIMD, a redundant or spare SIMD is integrated with the remaining operational SIMDs. This approach is referred to herein as SIMD repair. [0045] Returning back to FIG. 6 , and as noted above, arrangement 600 is configured to facilitate detection and segregation of faulty logic components, such as defective SIMDs, in IC dies. During operation, scheduler 602 receives work items 604 and distributes those work items across SIMDs 0 -N along a communications bus 610 . Communications bus 610 , then forwards the work items across SIMDs 0 -N to the local processing units, such as ALUs 0 -N, respectively. [0046] Each of the SIMDs 0 -N can perform an equal share, or a predetermined percentage, of the distributed work items. Alternatively, each of the SIMDs 0 -N can or can operate under any one of known work distribution schemes, such as round robin, or in accordance with a time quanta. In one exemplary approach, after each SIMD completes its assigned work item (e.g., computations), in serial fashion for example, it forwards the results of its work to an adjacent SIMD within the SIMD group 606 . [0047] Although ALUs 0 -N reside within respective SIMDs 0 -N, ALUs 0 -N also operate as components of multiplexer 608 . Multiplexer 608 also includes respective configuration registers R 0 -RN to indicate whether its respective ALU is defective. Each configuration register R 0 -RN, for example, records the operational status (i.e., determination of defectiveness) of its corresponding SIMD. [0048] In the exemplary illustration of FIG. 6 , when a defect occurs in one of the SIMDs 0 -N, a defect bit is set in its corresponding configuration register R 0 -RN. The setting of the defect bit within the configuration register signals multiplexer 608 that work should not be distributed to the corresponding defective SIMD. Multiplexer 608 and scheduler 602 cooperatively remove the functionality of the defective SIMD from the communications bus 610 . [0049] At the same time, scheduler 602 can simply redistribute work across all remaining available SIMDs, or via multiplexer 608 , can switch in a redundant SIMD, such as SIMD (X) illustrated in FIG. 7 , and switch out the defective SIMD. During an exemplary operation, work that would have been assigned to the defective SIMD can simply be passed through that SIMD to adjacent SIMDs or to the redundant SIMD (X). Although the work (e.g., data) is passed through the defective SIMD, the defective SIMD will not perform any computational work on that data. The functionality or load of the defective device is spread across the other remaining devices. Each SIMD is capable of performing the work of all of the other SIMDs. In this manner, when one SIMD is taken out, the work load is absorbed by the remaining SIMDs. [0050] By way of example, once a SIMD becomes defective, a signal can be transmitted from the defective SIMD, for example, forwarding instructions to the multiplexer. In this manner, scheduler 602 then knows, for example, there are now three operational SIMDs out of the four SIMDs. As a consequence, and as noted above, scheduler 602 then redistributes the work items 604 across the three remaining operational SIMDs instead of the four total SIMDs. Control registers R 0 -RN, local ALUs 0 -N, and communications bus 610 provide a mechanism by which scheduler 602 knows to activate and deactivate specific SIMDs that failed during activation. This information is available to scheduler 602 by virtue of the corresponding control register's defect bit being set and read by scheduler 602 . Stated another way, embodiments of the present invention enable scheduler 602 to know when one of SIMDs 0 -N is defective. [0051] Other aspects of the present invention facilitate segregating logic within a SIMD to discern “must work” logic vs. “can be allowed to fail” logic. To accommodate this feature, there are changes within the RTL aspect of the IC chip design in which segregating logic is provided. This segregating logic aids in distinguishing sections of the SIMD that have failed and render the device inoperable from sections that can still perform work after having experienced some level of failure. Otherwise, a single defect can destroy an entire IC device. Desirably, all defective logic devices have been segregated prior to the wafer testing phase. Aspects and features of the present invention facilitate this process. [0052] As noted above, during the IC device power-up phase, scheduler 602 reads each of the control registers R 0 -RN to determine whether any of the SIMDs 0 -N is defective and identifies the defective SIMDs. During power up, for example, scheduler 602 may know it is scheduled to receive work-items 604 and that work-items 604 must be distributed across all of the computational resources (e.g., SIMDs 0 -N). Scan testing, performed in accordance with embodiments of the present invention, enables the segregation of, and compensation for, defective SIMD logic. [0053] FIG. 8 is an illustration of exemplary scan test methodology 800 provided in accordance with an embodiment of the present invention. Within methodology 800 , logic components within individual SIMDs can be tested to determine whether defective logic components exist and if so, whether they can be segregated from non-defective components. [0054] As understood by those of skill in the art, SIMDs are comprised, among other things, of large numbers of flip-flops. These individual flip-flops can be tested via a special test process referred to herein as “scan in” and “scan out.” During scan in and scan out, a predefined test pattern is shifted in and shifted out of the flip-flop scan chains, such as scan chains 406 ( a ), 406 ( b ), and 412 ( a ) shown in. FIG. 4 . In the embodiments, for example, a known bit stream can be provided as an input to the scan chain. This known bit stream is compared with the bit stream that appears at the output of the scan chain to distinguish “must work” components (e.g., 412 ) from “allowed to fail” components (e.g., 406 ). [0055] In test methodology 800 of FIG. 8 , for example, a SIMD 1 is configured to receive a known bit stream (not shown) at a “scan in” input pin 801 . The test bit stream is then transmitted through the flip-flop scan chain 802 and is provided at a scan out output pin 804 . As depicted in FIG. 8 , scan chain 802 is a “must work” scan chain. The output bit stream is compared (e.g., via use of a comparator) with the input bit stream to determine whether logic defects exist in components of the must work scan chain 802 . [0056] At the same time, another known bit stream is provided to input pin 806 of SIMD 1 to test the “allowed to fail” scan chain 807 . This input bit stream is compared with the output bit stream appearing at an output pin 808 to determine whether logic defects exist in components of the allowed to fail scan chain 807 . [0057] The information gathered from the test methodology 800 of FIG. 8 provides instrumental data for use during the gate level design (GLD) phase (i.e., 504 of FIG. 5 ). For example, if a defect was recorded in the must work scan chain 802 , during the GLD infrastructure design associated with SIMD 1 , the IC chip can be discarded. This precludes the need to perform ATE testing, which can save significant time and costs since testing time is a significant portion of IC device cost. [0058] In the exemplary embodiment of FIG. 8 , the tested bit streams (i.e., test pattern) are representative of the internal logic structure of SIMD 1 . In other words, during high-level RTL design (i.e., 502 of FIG. 5 ), at least two sets of scan chains are designed. One set is the “must work” scan chain and the other set is “an allowed to fail” scan chain. This design is then sent to a GLD development group where it is determined how to test the IC device that has been produced. The high-level IC design is then synthesized and made into gates during the level design. Finally, during the tape out process, the design is made into a chip and is turned into silicon. The silicon IC chip is then tested during ATE testing (i.e., 506 of FIG. 5 ). [0059] FIG. 9 is an exemplary illustration of a test configuration 900 constructed to perform testing methodology 800 illustrated in FIG. 8 in accordance with an embodiment of the present invention. More specifically, in FIG. 9 , test configuration 900 , including an ATE tester mechanism 902 , can be configured to test SIMD 1 in accordance with testing methodology 800 . [0060] In FIG. 9 , ATE tester mechanism 902 is configured to transmit the bit stream (e.g., logical 1s and 0s) through SIMD 1 and read the output bit stream. This technique provides an ability to isolate SIMDs determined have defective logic components during testing. In the embodiment, ATE tester mechanism 902 is coupled to a must work scan in/scan out register 904 , and an allowed to fail scan in/scan out register 906 . A first test pattern is configured for input to the register 904 in order to determine the operational status of logic within the must work scan chain 802 . Similarly, a second test pattern is provided as an input to register 906 in order to determine the operational status of logic within the allowed to fail scan chain 807 . [0061] An e-fuse module 908 is coupled to tester 902 . E-fuse module 908 includes pins, fuses, and other circuitry that facilitate special programming. This special programming facilitates identification, tracking, and compensation for defects that occur within the logic device sub-modules (e.g. flip-flops) of logic devices being tested. [0062] For example, when a user performs an ATE test, e-fuse module 908 enables the user to determine whether logic within one of the SIMDs 0 -N has a defect. In the example, the user will also know the defect has not only occurred in SIMD 1 , of the SIMDs 0 -N, but which sub-modules within SIMD 1 have failed. The information available via e-fuse module 908 also enables the user to know whether the defects within SIMD 1 are “stop and fail” or “continue and fail” type defects. [0063] During the example above, tester 902 can be configured to apply a voltage to fuses associated logic sub-modules within SIMD 1 such that when a user receives IC chip 106 , and places it on a circuit board, the circuit board is powered up, SIMD 1 is automatically de-activated if defects therein are of the “stop and fail” type. E-fuse module 908 also permits writing to one or more of the corresponding control registers R 0 -RN to isolate the identified defective SIMD and compensate for its deactivation. [0064] During an exemplary operational scenario, a tester can load these patterns from a file that specifies timing and voltage levels of signals to be applied to a SIMD under test via tester 902 . Multiple test patterns can be provided in order to test greater numbers of logic components within each SIMD. [0065] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present invention as contemplated by the inventor(s), and thus, are not intended to limit the present invention and the appended claims in any way. [0066] The present invention has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. [0067] The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance. [0068] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.	Provided is an apparatus including a scheduler and a plurality of logic devices coupled to the scheduler, each including a defect indicator. The scheduler determines whether one or more of the logic devices is defective based upon its respective defect indicator. The scheduler intentionally omits sending workloads to the disabled logic units, and thus enables the device to be functional albeit at a lower performance or in a differently performing product.	6
BACKGROUND OF THE INVENTION This invention relates to the marking for identification purposes of sheet articles of non-conductive material, particularly such articles which are in paper sheet form e.g. banknotes, passports and bonds. One method of marking articles of paper sheet material so that the articles can be identified and their authenticity thereby checked involves the incorporation herein of a detectable material which however must not alter too much the appearance and properties of the article. The proportion of detectable material incorporated into the articles must therefore in general be small. Furthermore, it is generally desirable that the detection system by very sensitive, that it be capable of rapid response in order to allow identification of the article at high speeds, and that it should provide a reliable means for repeated identifications of the same articles. Finally, it is also desirable that the detectable material be capable of producing a specific response, which can difficultly be imitated by other materials, in order to avoid successful counterfeiting of the markings. SUMMARY OF THE INVENTION The invention is concerned with a novel method of identifying and checking the authenticity of articles of non-conductive sheet material capable of allowing microwave radiation impinging thereon to pass therethrough (and preferably such articles which are in paper sheet form e.g. banknotes, passports and bonds), which articles are marked for identification purposes by the incorporation therein of a small quantity of very thin conductive fibres which are capable of absorbing and reflecting certain substantial proportions of the energy of microwave radiation impinging thereon. There articles are hereinafter referred to as "marked articles as herein defined". According to one feature of the present invention, there is provided a method for producing an identification signal for marked articles as herein defined and checking their authenticity wherein the part of the article in which the very thin conductive fibres are incorporated is placed in the path of an unguided microwave beam and the excess of microwave radiation energy arrested over the energy reflected is measured, and an output signal is produced which is representative of the presence of such excess. According to a still further feature of the present invention, there is provided apparatus for use in a method according to the invention as hereinbefore defined, which apparatus comprises an emitter of an unguided beam of microwaves; means for positioning the article to be identified with the part of the sheet article in which the very thin conductive fibres are incorporated in the path of an unguided microwave beam from the said emitter; a first receiver positioned so that in use it receives energy from the part of the said beam which passes through the said article and is neither absorbed nor reflected; a second receiver positioned so that in use it receives energy from the part of the said beam which is reflected by the very thin conductive fibres incorporated in the said article; and a comparator connected to the output of both receivers, adapted to deliver an output signal in response to a significant excess of the energy arrested, as measured by the first receiver, over the energy reflected, as measured by the second receiver. The energy arrested is the energy which is neither absorbed nor reflected, and is measured by the reduction of received energy by the first receiver with respect to the energy received in absence of the sheet article. The marked articles as herein defined which are in paper sheet form are themselves novel articles. Thus, according to a still further feature of the present invention, there are provided articles of paper sheet material capable of allowing microwave radiation impinging thereon to pass therethrough, which articles are marked for identification purposes by the incorporation therein of a small quantity of very thin conductive fibres which are capable of absorbing and reflecting certain substantial proportions of the energy of microwave radiation impinging thereon. When using a microwave beam for the detection of metallic material, it is common simply to measure the proportion of the energy of the beam reflected by the metallic material. This would however be unsuitable as a reliable means of identification for use in the method of the present invention because the reflection characteristics of a particular article could too easily be copied e.g. by the use of metal powders or reflecting strips. The property of absorbing a detectable proportion of the energy of a microwave beam is however one which is characteristic of very thin conductive fibres, and for this reason it is important in the method according to the invention to measure the proportion of the energy of the microwave beam which is absorbed. This is characteristic of the very thin conductive fibres in the articles and is not easy to imitate. In the method according to the invention the proportion of the energy of the microwave beam which is absorbed is measured in an indirect way, by measuring the proportion of microwave energy which passes through the article or a selected part thereof (and thus the proportion of microwave energy arrested by the article or part thereof) and separately measuring the proportion of microwave energy reflected. The energy that is arrested but not reflected is then the energy absorbed. The energy arrested by the conductive fibres in the article can be calculated by measuring the reduction in the energy of the beam after passing through the article and comparing this with the reduction observed using a similar reference article but without the conductive fibres. The energy arrested by the reference article can then be set as the reference zero value for direct reading of the energy arrested by the conductive fibres. In a similar way the energy reflected by the conductive fibres in the article can be calculated by comparing the energy reflected by the article with the energy reflected by the reference article. The absorbed energy is then the difference between these two values of energy arrested and energy reflected. In utilising the method according to the invention to check the authenticity of articles, care must be taken in two respects. First, the measured values of energy arrested and energy reflected are in general large as compared with their difference. If these values are not measured in an accurate way, i.e. with only small probabilities of error, their difference proportionally presents too large variations to be significant as a measure of energy absorbed. When the microwaves are guided inside a waveguide which is traversed by the article clamped between two waveguide sections and the energy transmitted through and reflected by the article are measured, the errors in the measurements are in general too large. When the microwaves are emitted by an emitter antenna so as to form an unguided beam (i.e. without surrounding waveguide) which passes through the article towards a first receiver antenna and which is reflected by the article towards a second receiver antenna, however, then it has been found to be possible to measure the proportions of the energy which pass through and are reflected by the article (and thus also the energy which is absorbed by the article) with sufficient accuracy for the purpose of the method according to the invention. The second point which requires care when practising the present invention is the selection of very thin fibres having appropriate resistivity in order to provide the desired capability of absorbing and reflecting substantial proportions of the energy of microwave radiation impinging thereon. The fibres, when under a microwave beam, act as dipole antennae. The absorption improves as the fibres become longer and thinner, but there are practical limits. For example, when very thin metallic fibres are to be incorporated into paper sheet, it appears to be desirable, for ease of mixing of the fibres with the sheet material, that the fibres have a length not greater than 40 mm and, to avoid undue expense in manufacture, a thickness of not less than 2μ. Fibres are in general conveniently used which have a thickness below 50λ, preferably in the range from 2 to 25μ, and a length not greater than 40 mm, preferably not greater than 10 mm. The internal resistivity of these fibres must be such as to provide, when operating in use as dipole antennae, a load impedance which is adapted relative to the entrance impedance so as to give sufficient absorption. For the microwave frequencies of 1 to 50 GHz which are in practice used and fibres with the above-mentioned dimensions, it has been found to be important to use for the fibres a metal having a conductivity of less than 10% of the conductivity of the copper standard (copper resistivity=1.7 μΩcm). Such metals are, for example, nichrome, titanium, silicon steel and stainless steel (73 μΩcm). BRIEF DESCRIPTION OF THE DRAWING The invention will now be further described with reference to the accompanying drawing, which shows a schematic view of an apparatus according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, the apparatus comprises an emitter oscillator 1, a variable attenuator 2, a directional coupler 3, an emitter-receiver antenna 4, a receiver antenna 5, a variable attenuator 6, a sensor 7 for the transmitted waves through the sheet article 10 in the gap between the antennae 4 and 5, and a sensor 8 for the waves which are reflected by the sheet article, re-enter antenna 4 and are directed by directional coupler 3 towards the sensor 8. The apparatus also comprises a comparator 9 which compares the value of the energy arrested P a , as measured by sensor 7, with the value of the energy reflected P r , as measured by sensor 8, and which delivers a signal S in response to a significant excess of P a over P r . In this embodiment, the emitter-oscillator 1 is a klystron, which generates microwaves of 9,500 Megahertz (wavelength about 3 cm). Alternatively, however, the oscillator can also be a Gunn-oscillator with a Gunn-diode in a resonant cavity for producing microwaves of similar wavelength. Oscillators such as the MA-86651C oscillator of Microwave Associates, Inc., are commercially available for burglar alarms, traffic control devices and other applications. The output of the resonant cavity is provided with a variable attenuator 2, which in this case is a small slot in a plate perpendicular to the direction of the waves at the output of the resonant cavity and which is rotatable in its plane for placing the slot approximately parallel with the E-field of these waves. The output of the oscillator with this attenuator is connected to a directional coupler HPX752A of Hewlett Packard, which is of the type where two adjacent waveguide sections have coupling holes in the common wall. One of the waveguides forms the transmission line from the output of the oscillator 1 and its attenuator 2 to the horn-antenna 4, i.e. from port 11 to port 12 of the directional coupler. The other waveguide has its end on the side of port 12 terminated with a matched load, and the other end forms port 13, as well known for this type of directional coupler. The directivity of this directional coupler is more than 40 dB, this being the proportion of the signal received at port 13 in response to an input signal at port 12, as compared with the signal received at the same port when the same input signal is applied at port 11. The coupling factor is about 3 dB, this being the energy loss of an input signal at port 12 travelling to port 13. Other directional circuits can be used, such as a ferrite circulator, commonly used in microwave transceivers for microwave reflection control systems. The output of the directional coupler 3 is provided with a horn antenna 4, which serves for adapting the impedance of the transmitting system to the impedance of the free space in which the antenna 4 emits a nearly parallel unguided beam of microwaves through the sheet article 10. The microwaves reflected by this sheet article enter the horn antenna 4 again in the opposite direction; the horn antenna 4 thus also acts as the antenna for the receiver of the reflected waves. These waves are further transmitted over entrance port 12 to output port 13 of the directional coupler and thence towards the sensor 8 for the reflected waves. The sensor 8 consists of a point contact diode, placed in the direction of the electric field at the end of a short waveguide section and connected to a suitable load resistance (e.g. diode MA-41205 of Microwave Associates Inc. with a load of 600Ω). The waves entering the sensor produce a DC-voltage across the load resistance, and this voltage is representative of the energy reflected. The voltage delivered by the point contact diode varies approximately as the square of the amplitude of the entering waves, and as the energy of these waves is also proportional to the square of the same amplitude, it can be concluded that in this case the voltage measured across the load is practically proportional to the energy of the entering waves. This feature is however not necessary for a sensor for use in apparatus according to the present invention insofar as the output of the sensor delivers a signal, analog or digital, proportional or not, which is representative of the value of the reflected energy i.e. provides a means of determining the magnitude P r of that energy. Schottky diodes can e.g. also be used as sensors for this purpose. At the side of the sheet article 10 which is remote from horn-antenna 4 is located another horn-antenna 5 which acts as the antenna of the receiver of the waves transmitted through the sheet article. This antenna is connected via a variable attenuator 6, of the same type as attenuator 2, to the microwave sensor 7, of the same type as sensor 8, which delivers at its output a signal representative of the energy transmitted through the sheet article 10. For the purpose of concluding whether or not there is absorption of a proportion of the microwaves impinging on sheet article 10, the readings of the output signals at sensors 7 and 8 are sufficient, even without attenuator 6. For this, a reference sheet article is placed between horn antennae 4 and 5, this sheet article being the same as the sheet article to be identified except that it does not have conductive fibres incorporated therein. The attenuator 2 is set so as to make the sensor 7 deliver its full scale voltage, in this case 200 mV. Then, a completely conducting metallic sheet, which reflects all microwave energy impinging thereon, is placed between the horn antennae 4 and 5 in place of the reference sheet article and the reading of the voltage at sensor 8 (in this case 119 mV) is taken as the full scale voltage for all the energy of the microwave beam being reflected. Finally, the sheet article to be identified is placed between the horn antennae 4 and 5 in place of metallic sheet. The output signal at sensor 7 will give a reading of which the percentage voltage drop (with respect to the full scale of 200 mV), is representative of the percentage of energy arrested by the conductive fibres of the sheet article to be identified. The percentage voltage rise above zero (100 percent being the full scale 119 mV voltage for the energy reflected) is representative of the percentage of energy reflected. The difference between percentage arrested and percentage reflected is then percentage absorbed. In order however to detect absorption in an automatic way, the additional attenuator 6 and a comparator 9, connected to the outputs of the sensors 7 and 8 of both receivers, are used. The apparatus is then operated as follows. First the metallic sheet is placed between the horn antennae and the attenuator 2 is set so as to allow sensor 8 to display its full scale reading. Then the reference sheet article is placed between the horn antennae and the attenuator 6 is set to display the same full scale reading. In such a way, for both sensors, a voltage rise or drop corresponds with a same rise or drop of energy received. The voltage drop of sensor 7 is proportional to the power arrested P a , and the voltage rise of sensor 8 is then proportional to P r , the power reflected, with the same proportionality factor. When there is no absorption, P a and P r must be equal to each other, and this comparison is made in comparator 9. The displays of sensors 7 and 8 are preferably made as digital voltmeters, and the comparator 9 is then of the digital type as well known in the art. When there is a significant excess of the reading of P a over P r , the comparator can be arranged to deliver a signal S which means that the sheet article to be checked has been identified as authentic. By significant excess is meant an excess beyond the variations to be expected as a result of the probabilities of error involved in making the measurements. For automatic detection, the attenuator 6 can be omitted if the volumeters of the comparator are made to take into account the difference of scale factors in the voltages produced in both sensors. This can be done e.g. by the use of scale amplifiers at the outputs of the voltage measuring devices, or in a digital way in the comparator. The apparatus according to the invention can also if desired include a comparator 9 wherein the output signal S is not merely a yes or no, but a signal which indicates the value of the difference between P a and P r . In such a way, microwave energy absorbing sheet articles can not only be distinguished from non-absorbing sheet articles, but two microwave energy absorbing articles can be distinguished from one another. Thus for example, one category of article can be provided with conductive fibres giving a certain value of absorption loss and a second category of article can be provided with conductive fibres giving a significantly different value of absorption loss. Alternatively, different categories of article can be made to give the same absorption loss but different reflection losses. In such a way identifiable distinctions can be provided between different categories of sheet articles, identification then being possible by measuring not only the value of the energy absorbed but also the value of the energy reflected and both values in combination giving the means of distinguishing different categories of sheet articles. Apparatus of this kind can then serve as machines for sorting different categories of sheet articles. As microwave signals have a very high speed of response, speeds of more than 10 meters per second are possible for the passage of sheet articles between the horn antennae 4 and 5 without the risk of confusing microwave signals resulting from adjacent paper sheet articles as they pass through the apparatus. The distance between the horn antennae 4 and 5 is preferably a fraction of a wavelength and the sheet article is preferably passed through the apparatus in a direction at right angles to the beam direction. In general, it is not necessary (although preferable) that the receiving antenna of the first receiver be so positioned as to receive substantially the whole of the transmitted beam. Similarly it is not necessary (although preferable) that the receiving antenna of the receiver for the reflected microwaves, which may be an antenna separate from the emitter antenna, be placed in a position to receive substantially the whole of the reflected beam; nor is it necessary (although it is again preferable) that substantially the whole of the microwave beam should impinge on the sheet article when in position for checking. The only necessary thing is that the values of P a and P r which are compared with each other must relate to the same part of the paper sheet article, which part must have conductive fibres incorporated therein. For a good sensitivity, however, the above-mentioned features which are not necessary although preferable are used in carrying out the method according to the invention. When using the method according to the invention, the conductive fibres in the sheet articles act as small dipole antennae with respect to the incident microwave beam. When these are randomly oriented in the plane of the sheet article, there is always a certain proportion of the fibres or fibre parts aligned with the E-field of the incident beam. If the fibres are not randomly oriented, the method will give different readings for different orientations of the sheet article and this must then be taken into account. As explained above, the absorption is greater as the conductive fibres become longer and thinner. For this reason the fibre thickness is always lower than 50μ, and this is the intended meaning of the expression "very thin" as used herein in relation to the fibres. A fibre thickness below 25μ is in general preferred; the absorption is then sufficient to allow sheet articles according to the invention to have less than 5% by weight of fibres. This is what is meant by the expression "small quantity" as used herein in relation to the amount of fibres incorporated into the articles according to the invention. A quantity of less than 0.5% by weight will be preferred. The very thin conductive fibres for use in the present invention can be obtained for example by the technique of bundle drawing as described e.g. in U.S. Pat. Nos. 2,050,298; 2,215,477; 3,029,496; 3,277,564; 3,698,863; and 3,394,213. As explained in these patents a number of fine wires, drawn in a conventional way to a diameter of e.g. 0.2 millimeter, are bundled together with a separation material between them and a metal casing around the bundle. The whole is then drawn in a number of passes through drawing dies of gradually smaller diameter, and the total reduction of the diameter is then equally distributed over the wires of the bundle. After drawing, the bundle is then submitted to a selective etching operation in which the casing and the separation material between the wire are etched off and the fine filaments remain for subsequent cutting into fibres. The separation material serves to avoid cold welds between filaments during drawing. The sheet articles according to the present invention are paper sheet articles. These can be made by conventional methods starting from an aqueous suspension of cellulosic fibres together with other paper ingredients and additives including for example polyvinyl acetate and other synthetic fibres. The conductive fibres are evenly distributed in this aqueous suspension. If difficulties in effecting even distribution arise, the fibres can firstly be introduced in the form of conglomerates of various fibres combined together, preferably in the form of bundles, by means of a water-soluble binder. During mixing, the binder then gradually dissolves and the fibres more readily disperse to provide an even distribution. For different percentages by weight of fibres and different fibre dimensions, the following values were measured (average of 5 measurements: average±spread) ______________________________________Length Diameter Percentage bymm μ weight % % arrested % reflected______________________________________5 12 4 85.4 ± 0.75 71.4 ± 3.25 12 1 32.5 ± 3.25 29.2 ± 35 22 4 19.0 ± 1.7 15.0 ± 1.343 22 4 9.0 ± 0.7 7.9 ± 0.7______________________________________ This table shows how important it is to have a method of measurement giving a low probability of error for the measured values. As absorption becomes less (e.g. due to shorter, thicker or fewer conductive fibres), it becomes increasingly difficult to establish whether there is a significant excess of arrested energy over reflected energy, i.e. whether the difference as between arrested energy and reflected energy is more than could result from errors in measurement. The lower the probability of error in the method of measurement, the fewer, the shorter and the thicker can the conductive fibres be. Fewer fibres are in general desirable in order not to alter the appearance and properties of the paper. Shorter fibres are desirable for better mixability e.g. in aqueous suspension for producing paper sheet articles. Thicker fibres require fewer drawing operations to produce and thus are in general cheaper to manufacture.	A method of producing an identification signal for a sheet article of non-conductive material, which article is marked for identification purposes by the incorporation therein of a small quantity of very thin conductive fibers which are capable of absorbing and reflecting certain substantial proportions of microwave radiation energy impinging thereon, which comprise placing the part of said article in which the very thin conductive fibers are incorporated in the path of an unguided microwave beam, measuring the excess of microwave radiation energy arrested over the energy reflected and producing an output signal which is representative of the presence of such excess.	3
This is a Continuation of application Ser. No. 10/172,003 filed Jun. 17, 2002, which in turn is Continuation of PCT/IE00/0061 filed Dec. 20, 2000. FIELD OF THE INVENTION The invention relates to a display device comprising: a photon source for emitting photons for a source image; the source comprising a plurality of pixels arranged in a surface; an intermediate optical system for direction of the emitted photons; a variable power optical system for modulating photon wavefront curvature from the intermediate optical system; and a final optical system for directing photons from the variable power optical system into a user's eye for viewing the source image with a perception of a changing image scene. PRIOR ART DISCUSSION PCT Patent Specification No. WO99/08145 (Isis Innovation) describes such a display device. Such display devices operate to present source images to a user's eyes so that the user has the perception of each source image pixel at any one of a continuum of distances. Applications of such a display device include investigation of the eye's accommodative response and stereoscopic image display without conflict between accommodation and vergence. A significant problem with optical systems for modulating photon wavefront curvature is due to the frequency and amplitude of optical element motion required. A display resolution of 1024×768 pixels refreshed (non-interlaced) at 60 Hz could require wavefront curvature to change at over 47 MHz. Mechanisms to translate or rotate optical elements at such frequencies by non-trivial amplitudes are bulky, expensive, and unreliable. Optical systems exist which circumvent the problem of high-frequency translation and rotation. For example, they allow high-frequency deformation of reflective surfaces or high-frequency variation of the index of refraction of refractive surfaces. However there are other problems associated with these at present, including: their switching speeds are slow—of the order of kHz; they have relatively small diameters; their modes of wavefront deformation are limited; they have limited optical power; and they can have poor photon transmission. Another problem relates to characteristics of pixels and their wavefronts. In order to realise many applications, some of which have been mentioned, the display should be capable of stimulating optically the eye's accommodative system. This requires not only appropriate wavefront curvature, but also a sufficiency of photons at appropriate wavelengths and a sufficient diameter of exit pupil for each pixel. Another problem is the aberration introduced by the optical system, especially if a wide field of view of the photon sources is required. A “wide angle” lens system can be used to reduce aberration across the field for a single, but not necessarily multiple, configurations of the device. A conventional “zoom” lens system of varying optical power can be used to reduce aberrations for multiple configurations, but increases the mass of optical elements to be moved. A related problem is the overall mass of more complex systems, particularly if the device is to be used as a head-mounted display. Display devices have been proposed which use the aforementioned non-rotating and non-translating optical systems to modulate wavefront curvature. However they do not overcome the problems outlined (especially the limitations of switching speed and diameter) in a practical, reliable, and cost-efficient manner, in order to simulate a wide field of view, high-resolution colour scene, with low aberration, in such a way as to stimulate optically the user's accommodative system. SUMMARY OF THE INVENTION According to the invention, there is a display device comprising: a photon source for emitting photons for a source image, the source comprising a plurality of pixels arranged in a surface; an intermediate optical system for direction of the emitted photons; a variable power optical system for modulating wavefront curvature of photons from the intermediate optical system; and a final optical system for directing photons from the variable power optical system into a user's eye for viewing the source image with a perception of a changing image scene; characterised in that the intermediate optical system comprises means for forming the photons into pencils, each pencil having photons from a single source pixel; the variable power optical system is positioned with respect to the intermediate optical system such that the pencils converge towards one another; the device further comprises a controller comprising means for receiving source image pixel co-ordinate data and intensity data, and data representing required perceived pixel distance, and for generating an output control signal for the variable power optical system, and an output control signal for the photon source, and the variable power optical system comprises means for dynamically altering the wavefront curvature of the pencils in response to the control signal. In one embodiment, the controller comprises means for presenting simultaneously all pixels that can be displayed with acceptable levels of aberration for a given state of the variable power optical system. In another embodiment, the controller comprises means for ordering the sequence of pixel presentation such that the magnitude of variable power optical system state change is minimised. In another embodiment, the intermediate optical system comprises a variable diameter aperture with two translational degrees of freedom, controlled by the controller. In a further embodiment, the final optical system comprises a concave mirror. In one embodiment, at least part of the intermediate optical system is positioned after the variable power optical system to direct the pencils to be parallel such that it is telecentric. In another embodiment, the intermediate optical system has a wide field of view of the photon source, encompassing an area wider than its physical size. In one embodiment, the controller comprises means for receiving inputs from an eye-tracking system for monitoring the look direction and accommodative state of the user, and for using said inputs when generating the control signal. In another embodiment, the controller comprises means for receiving inputs from the scene synthesis system for estimating the look direction and accommodative state of the user, and for using said inputs when generating the control signal. In one embodiment, the controller comprises means for receiving inputs from a wavefront sensor for monitoring the output of the variable power optical system, and for using said inputs when generating the control signal. DETAILED DESCRIPTION OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:— FIG. 1 is a systems-level schematic of a display device of the invention comprising eye-tracking, wavefront-sensing, scene synthesis, image synthesis, and video generation systems connected to an optical system; FIG. 2 is an optical schematic of the display device; FIG. 3 is an optical schematic of pencils from two different pixels in the photon source, converging towards, and filling, an aperture-limiting stop; and FIG. 4 is an optical schematic of the final optical system according to another embodiment of the invention, in which perceived locations of image points are represented. DESCRIPTION OF THE EMBODIMENTS Referring to FIG. 1 a display device 1 comprises the following data processing components and an optical system 2 : an eye tracking system 3 , a scene synthesis system 4 , an image synthesis system 5 , a video generation system 6 , and a wavefront sensing system 7 . These interface with a control system 8 , which in turn interfaces with components of the optical system 2 comprising:— a photon source 20 , having multiple pixels in a 2D surface, an intermediate optical system, in this embodiment a pencil-forming system 21 which forms the photons into pencils, each pencil having photons from a single pixel, and a variable power optical system 22 towards which pencils converge, and a final optical system 23 for directing photons into a user's eye E for viewing the source image. The photon source 20 comprises a conventional cathode-ray tube. The pixels emit photons in near-spherical wavefronts when excited by an electron beam scanned in a raster fashion via electromagnetic control. The pencil-forming (intermediate) optical system 21 comprises an objective subsystem 21 ( a ) and an imaging sub-system 21 ( b ), both of which are achromatic doublets, one on either side of the variable power optical system 22 . The objective sub-system 21 ( a ) is positioned such that its first principal focus lies at the surface of the photon source 20 . Aperture-limiting stops 24 of variable diameter and two degrees of translational freedom are positioned before the pencil-forming optical system 21 . The stops 24 comprise a liquid-crystal optical system, with pixels controllable to be either transparent or opaque. This controls the number, positions, and diameters of pencils passing through the pencil-forming optical system 21 . The variable power optical system 22 is positioned a distance d v before the second principal focus of the objective sub-system 21 ( a ) such that pencils are convergent towards it and fill its entrance pupil, as shown in FIG. 3 . Distance d v is calculated as follows, d v =csd vo /( sd o /f o ). where f o and sd o are the focal length and semi-diameter respectively of the objective sub-system 21 ( a ), sd vo is the semi-diameter of the variable power optical system 22 with respect to the optical axis of the objective sub-system 21 ( a ), sd s is the maximum semi-diameter of the photon source 20 , d o is the distance from the photon source 20 to the objective sub-system 21 ( a ), and c is a function of (sd s /d o ). The variable power optical system 22 comprises a micro-machined deformable mirror (MMDM). It is a reflective-coated elastic membrane under tension. With no force applied the membrane is planar. An electrostatic force, applied via a set of actuators spatially distributed behind the membrane, deforms it into a variety of concave shapes or modes. The variable power optical system 22 is not simply one of variable focal length, it can achieve complex deformation of wavefront curvature which allows it to correct many kinds of aberration introduced by other optical systems of the device. The angles between the optical axis of the variable power optical system 22 and the optical axes of the objective, sub-system 21 ( a ) and the imaging sub-system 21 ( b ) are minimised to reduce astigmatic aberration introduced by the tilt of the variable power optical system 22 . Since it is positioned where pencils converge towards it and diverge after it, a variable power optical system 22 with relatively small diameter does not necessarily limit the field of view in the object and imaging spaces of the pencil-forming optical system 21 . The imaging sub-system 21 ( b ) has positive optical power and brings pencils to points of focus before the final optical system 23 . It is positioned a distance (f i −d i ) after the variable power optical system 22 . Distance d i is calculated as follows, where sd i and f i are the semi-diameter and focal length respectively of the imaging sub-system 21 ( b ), and sd vi is the semi-diameter of the variable power optical system 22 measured with respect to the optical axis of imaging sub-system 21 ( b ): d i =sd vi /( sd i /f i ). This makes the imaging sub-system 21 ( b ) near-telecentric so that irradiance and angular size of field are not changed significantly by the variable power optical system 22 . The final optical system 23 comprises a conventional low-aberration wide field-of-view eyepiece, as used in microscopes, telescopes, and other viewing instruments. It provides a Newtonian view (where light passes through most of the eye's entrance pupil) of the image. The final optical system 23 is positioned such its first principal focus lies at the surface of pencil focus, formed by the imaging sub-system 21 ( b ), when the variable power optical system 22 is in a state of maximum power. This causes pencils exiting the final optical system 23 to have near-planar wavefronts and so corresponding image pixels are perceived by the user to be at near-infinite distances. When the variable power optical system 22 is in a state of minimum power, the surface of pencil focus formed by the imaging sub-system 21 ( b ) lies after the first principal focus of final optical system 23 . This causes pencils exiting the final optical system 23 to have near-spherical wavefronts of high curvature and so corresponding image pixels are perceived by the user to be at small distances. The control system 8 has inputs of pixel co-ordinates and intensities from the image synthesis system 5 and required perceived distance from the scene synthesis system 4 . It generates an output to the video generation system 6 of pixels to display simultaneously, an output to the variable aperture-limiting stop 24 of the position and diameter of pencils to form, and an output to control the variable power optical system 22 to modulate pencil wavefront curvature. Using look-direction and accommodative state inputs from an eye-tracking system 3 , the control system 8 identifies and outputs with least aberration those pixels that are being observed by the user. Using scene synthesis system 4 inputs, the control system 8 identifies and outputs with reduced aberration those pixels that are most-likely being observed by the user. Since switching and stabilising periods of the MMDM membrane of the variable power optical system 22 are proportional to the magnitude of shape change, the control system 8 orders the sequence of pixel output such that the total shape change required for each image has minimum magnitude. A pre-calculated table of aberration values for all pixels at a variety of distances and for a variety of variable power optical system 22 states is used by the control system 8 . Using the table to avoid run-time calculation, and estimating values through interpolation if necessary, the control system 8 identifies and outputs simultaneously all pixels that can be displayed with acceptable levels of aberration given the state of the variable power optical system 22 . A pre-calculated table of variable aperture-limiting stop 24 control signal values for all pixels at a variety of distances and for a variety of variable power optical system 22 states is also used by the control system 8 . Using the table to avoid run-time calculation, and estimating values through interpolation if necessary, the control system 8 outputs variable aperture-limiting stop 24 control signals. A pre-calculated table of a variety of variable power optical system 22 control signal values is available to the control system 8 . Using the table to avoid run-time calculation, and estimating values through interpolation if necessary, the control system 8 outputs variable power optical system 22 control signals. The table values are subsequently modified by the control system 8 if inputs from a wavefront-sensing system 7 indicate that they fail to achieve the required wavefront curvatures. Alternative embodiments of the invention 1 include the following: The photon source 20 can comprise a variety of video display technologies that form a surface of image pixels by emission or reflection of photons with near-spherical wavefronts, including: liquid crystal, plasma, light-emitting diode, and digital micro-mirror devices. The photon source 20 can also comprise a single source of photons with near-planar wavefronts raster-scanned—by mirrors under micro-electro-mechanical system control—through an array of optical elements with the appropriate refractive, diffractive, or diffusive characteristics such that pixels with near-spherical wavefronts are formed. Not all photons entering the eye need pass through all elements of the optical system 2 . Beam-splitters and other refractive or reflective elements may be used to direct photons along alternative optical paths. These photons may originate at a single or multiple photon sources 20 . In this case the controller 8 identifies and outputs the appropriate optical path for each image pixel. The objective 21 ( a ) and imaging 21 ( b ) sub-systems can comprise complex optical systems to minimise aberration over wide fields of view. Multiple variable power optical systems 22 may exist at a variety of positions along the optical path. The variable power optical system 22 can comprise a deformable reflective surface under piezo-electric, pneumatic, or mechanical control. The variable power optical system 22 can comprise an optical system with dynamically controllable indices of refraction across its surface. This facilitates selective spatial retardation and so control of wavefront shape. Electro-optic, acousto-optic, photo-optic and other “solid-state” materials can be used. Such variable power optical systems 22 are positioned as shown in FIG. 2, but since they are not reflective they do not fold the optical path. The imaging sub-system 21 ( b ) and the final optical system 23 can be integrated such that a real image surface is not necessarily formed. The final optical system 23 can comprise an off-axis concave mirror, as illustrated in a final optical system 40 in FIG. 4 . The axis of the concave mirror and the real image surface may be tilted significantly with respect to one-another, see angle A. Tilt is achieved by additional reflective or refractive elements between the image surface and the mirror, or by appropriately tilting the elements of the pencil-forming optical system 21 . Advantages of the invention include: the ability to stimulate accommodation optically through provision of sufficient photons at appropriate wavelengths, with appropriate wavefront curvature, and with a sufficiently large exit pupil; the large exit pupil also facilitates alignment of the eye with the display; the variable power optical system 22 corrects aberration introduced by other optical systems of the device, meaning that less complex optics are required in the other systems; the objective sub-system 21 ( a ) with wide field of view of the photon source 20 allows perception of high-resolution imagery without exceptionally small and densely-packed photon source elements; the telecentric imaging sub-system 21 ( b ) allows change of depth without change of irradiance or angular size of field; the positioning of the variable power optical system 22 does not limit fields of view with its relatively small diameter; the control system 8 compensates for the limited switching-speed of the variable power optical system 22 , allowing high-resolution imagery to be presented at conventional video rates. The invention is not limited to the embodiments described but may be varied in construction and detail.	A display device ( 1 ) has a photon source ( 20 ) that displays an image scene in which the user perceives points at differents distances, resulting in optical stimulation of the eye's accommodative response. This is achieved by an intermediate optical system ( 21 ) forming the photons into pencils and a variable power optical system ( 22 ) positioned for convergence of the pencils. A control system ( 8 ) controls the variable power optical system ( 22 ) to modulate photon wavefront curvature according to image pixel co-ordinate and intensity data and data representing required perceived pixel distance.	6
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to carbon black adsorbents, and further to a method for the formation of said adsorbents by gasification or partial combustion of liquid and/or solid combustibles, said process resulting in the formation of carbon pellets of separable carbon black. 2. Description of the Prior Art Carbon black, formed during the gasification or partial combustion of combustibles, is usually washed from the reaction gas stream with water. The resulting suspension of carbon black in the carbon black water is usually characterized by a large specific surface area and other properties typical of activated charcoal. The recovery of activated charcoal from carbon black has not been previously considered for a number of reasons, among which include: 1. The concentration of the carbon black in the carbon black water represents only about 1 percent by weight. Therefore, recovery of the carbon black by direct methods, such as filtration, is expensive. The separation and drying of the filter cake with a fraction of water of from 80 to 85 percent by weight causes further problems. 2. It is not possible to run a gasification set-up in a way as to guarantee the consistent quality of the carbon black, which is formed as a by-product. As a consequence, it is not possible to use measures which would stabilize the quality of carbon black (such as methods of activation), since, after drying, the carbon black is in the form of a loose powder. Since the direct recovery of carbon black has until now been economically uninteresting, two methods have been used in order to separate the carbon black from the running water containing it. In these methods, the carbon black is either extracted into oil directly or extracted into oil with a previous petroleum wash. The carbon-oil aggregates or the carbon pellets are then separated and burned. The desirable activated charcoal properties of the carbon black are destroyed, however, through contact of the carbon black with the oil, since the free surface area of the carbon black becomes coated. It is not possible to regenerate the carbon black, such as is known to occur with oil-laden activated charcoal or, at best, it is only possible under limited circumstances. The possibility of obtaining from the aforementioned pellets a useable activated charcoal, therefore, was not heretofore considered. SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide a technique for direct utilization of the carbon black pellets, above described, in an economically attractive manner. Another object of the present invention is to enable the use of the said carbon pellets as adsorbents having good activated charcoal properties. These and other objects of this invention as will hereafter become more clear from the following description have been attained by providing a method for the preparation of an adsorbent, which comprises: producing a carbon bearing water, by partial combustion or partial gasification of liquids and/or solid combustibles, separating said carbon black therefrom, aggregating said carbon black to form carbon black pellets, in an aggregation medium selected from the group consisting of oils, fats, waxes, distillation residues or mixtures thereof. and thereafter separating said carbon black pellets from the aggregation medium thereafter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It has now been unexpectedly found that the carbon black pellets can be simply, directly and economically decomposed into two valuable substances - remaining pellets and oil. The remaining carbon black has important advantages in comparison with the carbon black obtained by the direct route. While the filtered carbon black is prepared with up to 80 to 85 percent by weight of water, the remaining pellets of the present invention have only a water content of about maximum 30 percent by weight. Since these remaining pellets can be easily poured, such operations as transportation, storage and delivery afford no great problems. Because of their high porosity, drying can be attained without any problems. Because of the open pore structure of these remaining pellets, they are especially suited for specialized applications as well as for use in purification measures. Surprisingly, the remaining pellets possess a specific surface area of about 600 m 2 /g, so that they can be directly used as adsorbents. Besides, these remaining pellets can, as compared to filtered carbon black, still undergo further improvements in quality (such as activation). Experiments have shown, that through appropriate activation measures, said pellets can reach or even overtake the known parameters of commercial activated charcoal (specific surface area, absorption capacity). Following the aforementioned invention, it is possible, in an ordinary way, to recover a product with specifications which are clearly superior to the carbon black, obtained by direct means. Further it is possible, using the herein proposed technical methods to find a simple and advantageous solution to a variety of problems presented by the, up to now, ordinary methods of recovery of carbon black. The present invention therefore provides an adsorbent consisting of carbon pellets, which are a result of the partial gasification or partial combustion of oils, oil containing wastes or coal extracts, oil shale or sand, followed by the aggregation using oil, of the carbon black/carbon black water resulting from the aforementioned processes and finally from the separation of the carbon black from said oil. The present invention further provides a method to prepare an adsorbent, wherein the carbon black which is produced during the partial combustion/gasification of oils/or oil containing wastes, such as is produced from the extracts of coal, shale and sand, in the distilleries or petrochemical industry, is aggregated with oil with formation of carbon pellets, and said carbon pellets are then separated from their oil containing fraction. The separation of the oil containing fraction of said carbon pellets can be carried out by extraction, distillation, or thermal treatment, or a combination of these particular methods. As a solvent for the extraction, it is possible to use aliphatic, aromatic, or isocyclic hydrocarbons with at least four C-atoms. It is particularly useful to use low boiling petroleum ether. After the extraction, the remaining pellets are dried at a temperature of from 300 to 1100° C. so as to recover the solvent. If the thermal treatment is carried out at temperatures higher than 450° C., a cracking of the still adsorbed oil factions occur, whereby there is produced an enlargement of the specific surface area at the same time as an improvement is obtained in the pore structure of the remaining pellets. It is also possible to attain activation of the remaining pellets -- eventually even a consolidation or granulation -- at temperatures of from 800 to 1100° C. and with addition of CO--CO 2 and H 2 O. Having generally described the invention, a more complete understanding can be obtained by reference to certain specific examples, which are included for purposes of illustration only and are not intended to be limiting unless otherwise specified. EXAMPLE 1 The carbon black produced during the gasification of heavy oil is separated from the gas stream with water. Said water is then mixed and shaken with residue from the distillation, wherein the carbon black is aggregated by said oil in the form of pellets and can be separated as such. These pellets can then be extracted with low boiling petroleum ether (bp 80 to 100° C.) in a continuous extract. If one uses three parts by weight of solvent to one part by weight of pellets, then a three-stage extraction is sufficient to decrease the oil current of the pellets to about 4 to 5 percent by weight. The remaining micelles can be separated by distillation into solvent and oil. The solvent is taken back to the extraction, and the oil can be reused for the formation of new pellets or it can be processed further. The remaining pellets which are, after the extraction loaded with solvent, are then heated in an oven. The still remaining solvent fractions are thereby evaporated. After elimination of the solvent, the remaining pellets have, after the aforementioned extraction, a specific surface area of from 250 to 360 m 2 /g. The ash content of these remaining pellets is -- in comparison with the ash content of marketable, technical activated charcoal -- very low (about 1.6 percent by weight, with respect to the dried pellets). If drying in the oven is carried out at temperatures higher than 450° C., then the still remaining oil factions in the remaining pellets undergo cracking. With condensation of the vapors it is possible to recover the remaining solvent as well as the absorbed oil -- partially in the form of its cracking product in a quantitative fashion. The pellet masses shrink through the toasting by about 22 to 28 percent by weight and the specific surface area enlarges by larger than 600 m 2 /g. The absorbent which is obtained after toasting, is free of water and can be stored and transported without further problems. The toasted remaining pellets can be used as a valuable adsorbent directly or can be worked up further by activation to highly valuable activated charcoal. The data herein presented showed, that with a CO 2 -activation at 900 to 950° C. it was possible to obtain activated charcoal, with a specific surface area of 1,000 to 1,300 m 2 /g. These values are typical for the specific surface area of highly valuable (technical) activated charcoal. The corresponding methylene blue factors which are a measure of the specific decoloration capacity of activated charcoal, gave typical values between 18 and 24 ml of methylene blue solution (0.15 percent)/100 mgs of activated charcoal; these values thus are clearly higher than the corresponding values of a variety of activated charcoals (technical) (10 to 14). EXAMPLE 2 Carbon pellets were, after an intermediate storage further extracted of still remaining water droplets with a C 6 -cut in a Soxhlet extractor. The extraction time was about 1 hour excluding the starting and stopping of the Soxhlet. The at equilibrium still remaining solvent fractions were removed under mild conditions after said extraction. The final balance showed that 98 percent of the extractable oils had been extracted. After elimination of the remaining solvent fractions, the remaining pellets where dried in a nitrogen stream at 500° C. The loss in weight of the remaining pellets through prolysis of the remaining oil fractions yielded a value of 23 percent. The remaining pellets after toasting, had an ash content of 2.2 percent by weight and a specific surface area of 620 m 2 /g. A further fraction of these extracted pellets was activated at 950° C. in a quartz tube with CO 2 (20 1/h). The activation time was about 30 minutes. With a loss of about 55 percent by weight, a specific surface area of 1120 m 2 /g was obtained. The methylene blue test gave for this fraction a value of 21 ml of methylene blue solution (0.15 percent) per 100 mg weight.	An adsorbent consisting of carbon black pellets, which is formed by aggregation with oil/fats/waxes and other distillation residues of the water containing carbon black separated during the partial gasification/partial combustion of solids and/or liquid combustibles and wherein said aggregation medium is then separated.	2
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a motor speed control device, and in particular to a motor speed control device applied to a direct current (DC) fan. [0003] 2. Description of the Related Art [0004] Traditionally, when electronic devices function under heavy load, cooling fans operate at full speed. However, under light loading, fans generally continue to operate at full speed, wasting power, generating unnecessary noise, and reducing fan life. Accordingly, a method to control the rotation speed of the fan has been developed. As shown in FIG. 1 , when an electronic device functions under light loading, its inner temperature remains low. A thermistor RTH detects the temperature variation, adjusts its resistance accordingly, adjusts voltage and current from the power source, and outputs a signal to a driving circuit IC, which outputs a pulse width modulation (PWM) to a transistor TR, the switch frequency of which varies with duty cycle of the PWM signal, adjusting average current to the motor of the fan. Controlled rotation speed of the fan motor is thus achieved. The control theory is shown in FIG. 2 by way of explanation, in which supply voltage Vcc is 12V. The thermistor RTH detects temperature and accordingly generates voltage VTH. Reference voltage V 0 drives the fan at low speed. The duty cycle with the lowest driving voltage is determined by comparing oscillation voltage of the PWM signal and the reference voltage V 0 . The duty cycle modulation is controlled by comparing the oscillation voltage of the PWM signal and the voltage VTH from low speed from full speed. The fan functions at full speed if temperature exceeds a specific value. When the inner temperature increases, thermistor RTH decreases resistance, and the current increases to increase rotation speed, providing suitable heat dissipation. When the temperature decreases again, the thermistor RTH again increases resistance, thus decreasing the rotation speed of the fan. [0005] However, as shown in FIG. 1 , a voltage drop occurs at V CE terminal of the transistor TR in the work area. The transistor consumes much power and generates heat accordingly. Also, when power consumption is too high or input voltage from the power source is too low, the thermistor RTH cannot function normally, thereby generating excess heat and increasing the inner temperature of the computer system. SUMMARY OF THE INVENTION [0006] An object of the present invention is to provide a motor speed control device applied to a fan for controlling its rotation speed in different temperature ranges by a thermistor and a simple external circuit, easily controlling turning points of temperature when the fan functions at a relatively low speed. [0007] Accordingly, the motor speed control device of the present invention includes a thermal sensor detecting an environmental temperature of the fan, a driving element driving the fan to a specific rotation speed according to the detected temperature, and a control element connected electrically between the driving element and the thermal sensor for adjusting the first voltage of the thermal sensor to change the rotation speed and temperature range of the fan, wherein the thermal sensor is preferably a thermistor, and the driving element includes a Hall sensor and a driver IC. [0008] Preferably, the control element is a switch circuit including a comparator, a transistor, and two resistors, wherein one resistor of the switch circuit is electrically connected in parallel with the thermal sensor such that the first voltage rapidly decreases to be less than the reference voltage of the driving element to turn on the transistor and reduce the temperature range of the fan to the full speed. [0009] Alternatively, the control element includes a resistor electrically connected in serial with the thermal sensor and controlling the temperature range of the fan to the full speed by adjusting the resistance of the resistor and reducing the variation of the first voltage. [0010] The control element can be a subtraction circuit including a comparator and at least four resistors, wherein three resistors of the subtraction circuit form a second voltage to adjust a third voltage output to the driving element to reduce the temperature range of the fan to the full speed. [0011] Alternatively, the control element can be constituted by a division circuit, a comparator, and an output circuit, wherein when the first voltage exceeds the reference voltage of the driving element, the output circuit outputs a voltage equal to the reference voltage to be input to the driving element to keep the fan rotate at a low speed, and when the first voltage is smaller than the reference voltage of the driving element, the voltage input to the driving element is divided by N through the division circuit to quickly drive the fan to a full speed. [0012] A detailed description is given in the following embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: [0014] FIG. 1 is a schematic diagram of the control circuit of the conventional fan. [0015] FIG. 2 is a plot of control theory concerning the control circuit of the conventional fan. [0016] FIG. 3A is a schematic diagram of the first embodiment of the motor speed control device of the present invention. [0017] FIG. 3B plots variation between the temperature and rotation speed in the first embodiment of the motor speed control device of the present invention. [0018] FIG. 4A is a schematic diagram of the second embodiment of the motor speed control device of the present invention. [0019] FIG. 4B plots variation between the temperature and rotation speed in the second embodiment of the motor speed control device of the present invention. [0020] FIG. 5A is a schematic diagram of the third embodiment of the motor speed control device of the present invention. [0021] FIG. 5B plots variation between the temperature and rotation speed in the third embodiment of the motor speed control device of the present invention. [0022] FIG. 6 is a schematic diagram of the fourth embodiment of the motor speed control device of the present invention. DETAILED DESCRIPTION OF THE INVENTION [heading-0023] First Embodiment [0024] FIG. 3A is a schematic diagram of the first embodiment of the motor speed control device of the present invention. As shown in FIG. 3 , a power source supplies voltage to start fan rotation by inter-induction between winding coils and magnetic rings of the motor. A Hall induction integration circuit IC 2 detects electric waves induced by magnetic field variation between winding coils and magnetic rings of the fan. After, the Hall induction IC IC 2 outputs two positive and negative voltages to a driving integration circuit IC 1 . Thus, the circuit IC 1 and the circuit IC 2 constitute a driving element to drive the fan and send a feedback periodic pulse signal. [0025] As well, the driving element is connected to a thermal sensor (or a thermistor) RTH and a switch circuit, wherein the switch circuit 31 includes a comparator, a transistor TR 1 , and two resistors R 0 and R 5 (as indicated by the dotted line in FIG. 3A ). The thermal sensor RTH has various resistances at different temperatures, whereby first voltage V 1 from thermal sensor RTH and the resistor R 3 varies with temperature. Second voltage (or reference voltage) V 2 is formed by the resistors R 1 and R 2 . A comparator compares the first voltage V 1 and the second voltage V 2 , and accordingly adjusts the third voltage V 3 output therefrom. Therefore, the current varies when the transistor TR 1 is turned on, and the rotation speed of the fan varies accordingly, thus achieving the goal of speed control by temperature. [0026] FIG. 3B plots variation between the temperature and rotation speed in the first embodiment of the motor speed control device of the present invention. FIG. 3B shows variations in the slope between temperature and rotation speed of the fan before and after the circuit IC 1 is connected with the switch circuit. Without the switch circuit, the slope from temperature T 1 to T 2 is A. With the switch circuit, the resistor R 5 and the thermal sensor RTH are connected in parallel, the first voltage V 1 drops rapidly such that the reference voltage V 2 exceeds the first voltage V 1 , and the transistor TR 1 is turned on, thus reducing temperature range of speed variation (from T 1 to T 3 ). The slope B from temperature T 1 to T 3 exceeds the slope A without the switch circuit, so rotation speed of the fan is raised from low S 1 to high S 2 rapidly and sharply. Temperature range of speed variation is thus reduced by controlling the first voltage V 1 . [heading-0027] Second Embodiment [0028] FIG. 4A is a schematic diagram of the second embodiment of the motor speed control device of the present invention. As shown in FIG. 4A , the detailed circuit and control theory are similar to those in the first embodiment. The difference between these two embodiments lies in a resistor R 4 electrically connected with the thermal sensor RTH in series in this embodiment, unlike the switch circuit of the first embodiment. [0029] FIG. 4B plots variation between the temperature and rotation speed in the second embodiment of the motor speed control device of the present invention. FIG. 4B shows variations in the slope between temperature and rotation speed of the fan before and after the resistor R 4 is connected with the thermal sensor RTH in series. Without the resistor R 4 , the slope from temperature T 1 to T 2 is A. After the resistor R 4 is connected with the thermal sensor RTH in series, variation of the first voltage V 1 decreases. Temperature range from T 2 to T 3 , controlled by the resistance of the resistor R 4 , presents a smaller slope C. [heading-0030] Third Embodiment [0031] FIG. 5A is a schematic diagram of the third embodiment of the motor speed control device of the present invention. As shown in FIG. 5A , the detailed circuit and control theory are similar to those in the first embodiment. The difference between these two embodiments lies in a subtraction circuit 51 of this embodiment replacing the switch circuit of the first embodiment. The subtraction circuit 51 includes a comparator and six resistors R 6 , R 7 , R 8 , R 9 , R 10 , and R 11 , as indicated by the dotted line in FIG. 5A . [0032] FIG. 5B plots variation between the temperature and rotation speed in the third embodiment of the motor speed control device of the present invention. As shown in FIG. 5B , when resistances of the resistors R 6 , R 7 , R 8 , and R 11 are equal, voltage V 5 equals voltage of voltage V 4 taken away from voltage V 1 . Temperature range of the fan at full speed is thus reduced by adjusting fourth voltage V 4 , whereby the slope changes from A to a larger value D. [heading-0033] Fourth Embodiment [0034] FIG. 6 is a schematic diagram of the fourth embodiment of the motor speed control device of the present invention. As shown in FIG. 6 , the detailed circuit and control theory are similar to those in the first embodiment. The difference between these two embodiments lies in the switch circuit of the first embodiment being replaced with a division circuit 61 , a comparison circuit 62 , and an output circuit 63 . [0035] When the second voltage (or the reference voltage) V 2 is smaller than the first voltage V 1 , the output circuit 63 outputs a voltage equal to the second voltage V 2 to the circuit IC 1 so as to keep the fan at a low speed. When the second voltage V 2 exceeds the first voltage V 1 , the voltage input to the circuit IC 1 divided by N (N is a natural number) through the division circuit 61 . Therefore, the desired voltage (Vcc×16%) is rapidly achieved for stably controlling the rotation speed when the fan functions at a low speed. [0036] In conclusion, the motor speed control device is applied to a DC fan for effectively and stably controlling different speeds (from low to full) and the rotation speed in different temperature ranges. [0037] While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.	A motor speed control device. The motor speed control device applied to a direct current (DC) fan includes a driving element constituted by a driving IC and Hall IC, a thermal sensor and a control element electrically connected between the driving element and the thermal sensor. The present invention utilizes a thermal sensor and a simple control element to effectively and stably control the variable speed of the fan within different temperature ranges.	7
BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to improvements in security features in paper, and in particular to a method of making paper and transparentising selected areas of paper to provide enhanced security features. 2. The Prior Art Documents of value and means of identification, such as banknotes, passports, identification cards and the like, are vulnerable to copying or counterfeiting. The increasing popularity of colour photocopiers and other imaging systems, and the improving technical quality of colour photocopiers, has led to an increase in the counterfeiting of such documentation. There is, therefore, a need to improve the security features of such documentation, or paper, to add additional security features or to enhance the perceptions and resistance to simulation of existing features. Steps have already been taken to introduce optically variable features into such documentation which cannot be reproduced by a photo-copier. There is thus a demand to introduce features which are discernible by the naked eye but "invisible" to, or viewed differently by, a photocopier. Since a photo-copying process typically involves reflecting high energy light of an original document containing the image to be copied, one solution is to incorporate one or more features into the document which have a different perception in reflected and transmitted light. Known examples of such security features include watermarks, embedded security threads, fluorescent pigment and the like. EP-A2-0203499 discloses a method of applying a pseudo watermark to paper. This method comprises the preparation of a paper containing thermally sensitive material, the presence of which renders the translucency of the paper variable by temperature change. When heat is subsequently applied to a part of the surface of the paper, a region of the paper becomes semi-translucent. U.S. Pat. No. 2,021,141 discloses a method of applying pseudo watermarks to paper, by applying a resinous composition to finished paper which permeates the paper and causes it to become more transparent, or translucent, than the surrounding area. GB-A-1489084 describes a method of producing a simulated watermark in a sheet of paper. The sheet is impregnated in the desired watermark pattern with a transparentising composition which, when submitted to ultra violet radiation, polymerizes to form a simulated watermark. U.S. Pat. No. 5,118,526 describes a method of producing simulated watermarks by applying heat, in the desired watermark pattern, onto a thin solid matrix of waxy material placed in contact with a sheet of paper. This results in an impression of a durable translucent watermark. U.S. Pat. No. 4,513,056 relates to a process for rendering paper either wholly or partially transparent by impregnation in a special bath of a transparentization resin and subsequent heat cross-linking of the resin. EP-A1-0388090 describes a method of combining a see-through or print-through feature with a region of paper which has a substantially uniform transparency which is more transparent than the majority of the remainder of the sheet. JP 61-41397 discloses a method for making paper transparent and a method for its manufacture for see-through window envelopes. The method utilises the effect of causing ink cross-linked by ultra-violet rays to permeate paper thus causing that part of the paper to become transparent. All of these methods providing enhanced security features are for use with finished paper and for non-currency and non-security papers. They can be applied to wood pulp based papers for high volume commercial applications. Such substances are still quite porous with little inherent oil or grease resistance and the transparentising can be successful. Furthermore, in such applications it is highly desirable to have the transparentization step as a separate process. Web printing processes are very fast, whereas paper making processes are often much slower. Since there is a certain amount of spoilage in paper making, incorporating an additional process in the paper making has generally been avoided to avoid an increase in the spoilage. None of the prior art method are furthermore particularly suitable for low absorbency low porosity papers, such as are used for banknotes (banknote paper typically will exhibit a porosity of up to 25 ml/minute, measured by the Bendtsen method). Such papers have generally been treated so as to minimise the uptake of oily substances and organic solvents. This is generally achieved by using a fibrous substrate designed to reduce the porosity of the paper and by impregnating the paper with any one of a variety of sizing resins such as polyvinylalcohol or gelatine and also by calendering the paper. The sizing and calendering processes help to reduce the porosity of the paper. Finished paper treated in this way does not lend itself to transparentization because its low absorbency inhibits the penetration of the transparentising resin, and, in the case of UV cured resins or those requiring a hot drying process, the moisture content of the paper is disturbed and this is likely to cause print runability problems at the print stage. It is an object of the present invention to provide a method of manufacturing paper, in particular security paper, of which at least a portion is transparentized to provide an enhanced security feature in counterfeiting or copying. SUMMARY OF THE INVENTION According to the invention there is provided a method of making security paper comprising the steps of depositing fibers onto a support surface to form an unfinished porous absorbent sheet, applying a transparentising resin to at least a portion of said porous sheet, subsequently impregnating the porous sheet with a sizing resin, and then further processing it to form a sheet of finished security paper. A preferred embodiment of the present invention will now be described in detail, by way of example only, with references to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic section through apparatus used in a method of manufacturing paper according to the invention; FIG. 2 is a schematic section through alternative paper making apparatus for use in the method of manufacturing paper according to the invention; FIG. 3 is a perspective view of the rotary screen printer of FIG. 1; FIG. 4 is a schematic representation of a security document made from paper according to the invention; and FIG. 5 is a schematic representation of an alternate security document made from paper according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is shown a cylinder mold paper making machine 10 comprises a vat 11 containing paper stock, i.e., a suspension of paper making fibers 12. The major portion of a horizontal cylinder mold 13 dips into the vat 11. The surface of the cylinder 13 is provided by a wire mesh which may be embossed and generally there are several layers of mesh employed, the outermost being the finest. Liquid is drawn through the mesh as the cylinder 13 is rotated causing paper making fibers to deposit on the mesh and form wet paper 14. The wet paper 14 is couched from the cylinder by couch roll 15 and conveyed away on a moving wire mesh 16. The wet paper 14 then passes through a wet press 17 which squeezes the paper 14 to remove excess water therefrom. The paper 14 is then dried over heated cylinders 19. Although the present invention is described with reference to a cylinder mold paper making machine, which is the preferred method, the paper forming process can be achieved in many other ways. The most common alternative is the Fourdrinier system shown in FIG. 2. In this paper making machine fibre stock is deposited from a stock applicator or flow box 30 on to a continuous moving wire mesh 31. Water from the fibre stock drains through the wire mesh 31 leaving a wet de-watered fibre mat 32. The fibre mat 32 passes under a dandy roll 33 which can be used to apply an embossed watermark. The wet paper then passes through a wet press 34 before being dried. In a traditional paper making process the paper is impregnated with any one of a variety of sizing resins such as polyvinylalcohol (PVOH) or gelatin, to minimise the uptake of oily substances or organic solvents. The paper sheet 14 is passed through a size bath 18 so that it becomes saturated with size. The resulting paper is thus resistant to grease and has a lower abosorbency and it is therefore more appropriate for use as banknote paper and the like. The paper sheet 14 is then passed through an air float or spar dryer 20 for further drying before passing to a calendering device 21 to give a smooth surface before reeling 22. In the modified process according to the invention, a screen printing process or other resin applicator is used to apply a transparentising resin to the surface of the partially formed paper sheet 14 before it enters the size bath 18. This is shown in more detail in FIG. 3. The screen printer 23 is a rotary printer comprising a cylindrical screen 23 of flexible wire mesh mounted on a rigid steel rim covered by a stencil 24. The image required to be reproduced on the paper is formed in the stencil by means of an opening 25. As the paper sheet 14 passes the cylinder, the transparentising resin 26 is applied to the inside of the wire mesh and forced through the mesh with a squeegee blade 27 onto the paper sheet 14. At this point the partially formed paper is at its most absorbent, thus allowing good penetration of the transparentising resin. In one embodiment of the invention, no curing process is used, and the sheet 14 is passed directly into the size bath 18. This prevents smudging of the mobile transparentising resin which is effectively frozen in position. This is an unexpected effect. As soon as the sheet 14 enters the size bath 18, the size fills the cells in the paper surrounding those containing the transparentising resin, thus preventing migration of the latter. The transparentising resin can thus be applied to a sharply defined region of the paper so as to create a transparent patch or pattern that is capable of contributing to the overall and counterfeitability of a security document made from the paper. The security document may be a banknote, a cheque, a passport, an identification card, a share certificate or the like. An example of a security document made by this process is illustrated in FIG. 4 which shows a sharply defined translucentized area 28. It should be noted that the transparentized area does not reflect as much light as the non-transparentized paper. Therefore the outline of the transparentized patch can be seen reasonably well in reflected light. This provides a further enhancement of the anticounterfeit ability of a security document as it shows benefits in reflected as well as transmitted light. In an alternative embodiment of the invention, the resin can be "fixed" by using EB or UV radiation cured resins whereby curing takes place shortly after application and prior to entry of the sheet 14 into the size bath 18. These resins have the advantage that, once cured, they are fixed and controlled. Alternatively, the radiation cross-linking could take place between the air float dryer and the calender thereby providing the transparentising resin for a longer period of time to penetrate the paper 14. When paper is produced using the process described, two additional techniques can be applied to the process in order to increase the receptivity of the paper sheet 14 to the transparentising resin. The resin can be applied to a low grammage part of the paper created by the well known processes of mold or dandy roll water marking. This results in a very significant enhancement of the watermark as the contrast between the light and dark areas in the watermark are significantly greater. In the case of mold made watermarks, this also has the advantage of the creating a local area low in opacifying pigment such as titanium dioxide which further increases the transparentising effect of the transparentising resin. Instead of applying a resin to a plain low grammage part of the paper, the transparentising resin can also be applied to a decorative watermark 29, as shown in FIG. 4. This significantly extends the usefulness of the transparentising features as a deterrent to counterfeiters by markedly increasing its visual complexity and by generating within it an easily recognizable yet difficult to copy image. When the translucency is controlled to give an opacity not less than 50%, an unexpected advantage is that the outline definition of the watermark is noticably enhanced. In yet another alternative embodiment of the invention, illustrated in FIG. 5, the resin can be applied as an outline or frame 36 around a watermark 37 or a low grammage patch of the paper which has the effect of drawing attention to the watermark. Alternatively, or in addition to the use in relation to a watermark, the transparentising resin can be applied to a streak in the paper. In the manufacturing of paper using a cylinder mold machine 10, it is possible to use a fibre locator to direct different types of fibers to certain places on the mold thus causing a streaking effect in the resulting paper. These different types of fibers may create a streak of more porous paper structure. Where such a streak is created it has the effect of enabling the transparentising resin to absorb into the area of streak better than the surrounding paper and as such can therefore be used to enhance the transparentising effect. Alternatively, or in addition, a dye may be added to the transparentising resin. This can provide a striking and aesthetically pleasing effect to the transparentised areas. If the dye is fluorescent a very important commercial advantage can be obtained since an ultra-violet lamp can give a transmitted fluorescence which is normally only available in reflected light. Additionally the flourescent transparentising resin may be applied to a decorative watermark. The result of the feature which, when viewed in UV transmitted light, reveals the watermark of the shadows. This is an unexpected effect and because of its striking appearance it is a useful security feature. In yet another embodiment of the invention, the effect of the transparentising resin can be enhanced by the known process of intaglio printing which has the effect of embossing the paper. The combination of heat and pressure used in the intaglio embossing process improves the distribution of resin through the paper, except in the case of non-thermo plastic resins such as the radiation cured type. In order to maximise the transparentising effect of the resin, paper with a minimum of titanium dioxide (TiO 2 ), added to make paper more opaque and even out appearance, or other opacifying pigment needs to be used so as to achieve satisfactory see-through and strike-through in non-transparent areas. In yet another embodiment of the invention, the transparent features applied in register with the watermark in both the machine and cross-direction. Unregistered features have the inherrent advantage of technical simplicity, but by the same token are considered by many to be easier to counterfeit in quantity than registered features. Such a process requires the use of optical detectors that identify the watermark position and feeds this information back to the electronic unit that controls the drive of the printing screen in the case of screen printing. Alternatively, in the case of other printing methods, web tension control may be the mechanism by which register is achieved. Examples of materials and compositions suitable for use in making paper according to the invention will be discussed as follows. Paper-Making Fibers Papers suitable for banknotes and security documentation are made from a variety of fibers such as linen, abaca, wood pulp, cotton and blends thereof. Wood pulp is commonly used in non-banknote security documents, whilst cotton is the preferred fibre for banknotes. These cotton fibresare often from waste materials, such as off-cuts from the textile industry. The processed fibers have a ribbon-like profile which have a high surface-to-surface contact area. However, to produce approprite cotton fibers for manufacturing banknote paper and the like. The fibers must be refined from their original tubular configuration by the mechanical process of defribrillation. In order achieve a high quality base paper, it is necessary to ensure that the preparation of the fibers is carefully carried out and that they are manipulated and defibrillated to the most appropriate length and orientation to achieve a good quality watermark, whilst also maintaining the high strength needed for paper. Such paper generally has a Schopper Riegler value of 45-70. Despite careful processing, the fibers are natural fibers and can vary from batch to batch, resulting in a variation of the porosity of the paper. Further porosity variations result from different specification demanded by different customers. Sizing Resins It should be noted that the sizing resins referred to are surface sizing resins, as opposed to internal sizing resins. Preferably, traditional sizing resins such as polyvinylalcohol (PVOH) or gelatin are used as functionally these are generally the most successful. There are, however, many other chemicals which can be used such as starch or emulsion based polymers. Because of the variation in the quality of the paper fibers, the concentration of the size may also be varied during processing. Transparentising Resins As mentioned above, these may be known ultra violet (UV) curable, non-curable and cross-linkable resins. The process of screen printing the transparentising resin onto the paper sheet 14 and the time taken for the resin to be absorbed into the paper depends, amongst other things, on the viscosity of the resin. As paper making machines run at different speeds and the properties of the base paper fibers can vary, it is necessary to control the viscosity of the resin in order to control the transparency of the paper. It is therefore recommended that two resins are taken from different ends of the viscosity spectrum, which can be blended to form a resin at an appropriate viscosity for the machine speed, the level of transparency to be achieved, the rate of absorbtion, and so on. Another option is also to add different levels of a wetting agent such as FC-430 Fluorad (trade mark) supplied by 3M which is a fluoroaliphatic polymericester. Thus if the base paper is of a lower porosity than ideal, such a wetting agent can be mixed with the resin and added at the screen printing stage. UV-Curable Resins--The preferred resins are 100% resins with no solvent incorporated. They have a Refraction Index in the region of 1.5 and a viscosity in the region of 400-1500 centipoise at 23° C. They should preferably be non-yellowing and transparent. As curable resins harden, it is also necessary that they should have appropriate physical strength requirements. For example, they must not be brittle when they are bent. Examples of such resins are Photomer 4061 (trade mark) which is a tripropylene glycol diacrylate and Photomer 5018 (trade mark) may be used, which is a polyester tetrofunctional acrylate, both supplied by Harcros Chemical (UK) Limited. These resins are generally at the opposite ends of the viscosity spectrum and can be combined to provide a suitable transparentising resin at an appropriate viscosity. Non-curable resins--The physical criteria for a suitable non-curable resin are basically the same as those of the UV curable resins. Suitable materials include polybutene material such as Hyvis 7 (trade mark) which is a polyisobutylene supplied by BP Chemicals or Hyvis 5 (trade mark) which is also a polyisobutylene supplied by BP Chemicals. Hyvis 5 has a higher viscosity than Hyvis 7. It should be noted that the non-curable resins generally stay in the liquid state and have no physical strength requirements. Cross-linkable resins--It is suggested that resins such as epoxy and alkyd resins may also be used. However, it is important that a number of these take some considerable time to cure. If the change has not taken place by the time the paper is reeled, the whole reel of paper is glued together or resin transfer to adjacent sheets can occur. When non-curable and cross-linkable resins are used, it is necessary that the amount added is carefully controlled. Since these resins do not actually cure, it is important that the paper is not saturated, which could mark adjacent paper on the reel.	The invention relates to improvements in security features in paper and in particular to a method of making paper and transparentising selected areas of paper to provide enhanced security features. The invention thus provides a method of making paper comprising the step of depositing fibers (12) onto a support surface (13) to form a porous absorbent sheet (14), applying a transparentising resin to at least portion of said porous sheet and subsequently impregnating the porous sheet with a sizing resin.	3
RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60/692,185, filed on Jun. 20, 2005, the entire teachings of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] Supercritical carbon dioxide (scCO 2 ) has attracted considerable attention in recent years as an alternative to conventional solvents for organic synthesis. This interest has been motivated by environmental and health considerations, as carbon dioxide is relatively nontoxic and nonflammable, inexpensive and widely available, and typically poses minimal problems with regard to waste disposal. The tunable solvent properties of scCO 2 have also attracted interest, as relatively small changes in temperature and pressure can often allow for significant changes in viscosity, density, and self-diffusivity. The successful application of scCO 2 as a reaction solvent for some synthetic transformations is now well documented. The rates and selectivities of Diels-Alder and dipolar cycloadditions in scCO 2 have been reported, as well as the development of protocols for effecting several Pd-catalyzed reactions in carbon dioxide. Other useful transformations that can be achieved in this “green” solvent include a number of oxidation reactions, catalytic hydrogenation, olefin metatheses, and enzyme-catalyzed organic reactions. [0003] To date, however, only a few examples have been reported of carbon-nitrogen bond formation in scCO 2 , principally due to the facility of the reaction of amines with this electrophilic solvent (vide infra). [0004] The Pictet-Spengler reaction is an important method for the synthesis of isoquinoline and indole alkaloids. The valuable medicinal properties associated with tetrahydroisoquinolines and tetrahydro-β-carbolines continues to fuel interest in the synthesis of these classes of heterocycles. In the Pictet-Spengler reaction, these ring systems are produced via the cyclization of iminium ions generated in situ by the condensation of aldehydes with β-arylethylamines. Attempts to achieve Pictet-Spengler reactions in scCO 2 have been unsuccessful. For example, reaction of amine 1 with formaldehyde using scCO 2 led to a mixture of oligomeric products and none of the desired tetrahydroisoquinoline: [0005] This result was not surprising, as it is well-documented that nucleophilic amines react with carbon dioxide to form carbamic acids of type 4 and ammonium carbamate salts of type 5 (eq 2). [0006] In the presence of scCO 2 , amine 1 is thus intercepted prior to reaction with the aldehyde, and subsequent condensation of 4 and 5 with HCHO leads to the formation of the observed oligomeric products. [0007] The reactivity of CO 2 toward basic amines poses a significant challenge that complicates the application of many nitrogen-heterocycle forming reactions in scCO 2 . Thus, there is a need in the art for general strategies for the utilization of amines (and amine derivatives) in scCO 2 , and and for the application of these strategies in C—N bond-forming reactions and the synthesis of nitrogen heterocycles. SUMMARY OF THE INVENTION [0008] Disclosed herein are methods for enabling Pictet-Spengler cyclization in the presence of CO 2 , particularly multiphasic scCO 2 /CO 2 -expanded liquid media. Moreover, these methods for conducting this important reaction in scCO 2 can be applicable to other C—N bond-forming processes as well. [0009] In one embodiment, the invention is directed to a method for preparing a protected amine compound represented by structural formula (I): wherein the dotted line - - - is a covalent bond or no bond. The method includes the step of, in the presence of superatmospheric CO 2 : intermolecularly reacting an iminium compound represented by structural formula (II) with a nucleophile represented as “Nu,” as shown below: or, intramolecularly reacting an iminium group of an iminium compound represented by structural formula (III), the iminium compound having a nucleophile Nu, with the nucleophile Nu of the iminium compound: thereby forming the protected amine compound. [0010] In structural formulas (I)-(III), R 0 is R 3 or R 3 ′; PG is an amine protecting group; R 1 , R 2 , and R 3 are each independently —H or an optionally substituted aliphatic, cycloaliphatic, nonaromatic heterocyclic, aryl, heteroaryl, aralkyl, or heteroaralkyl group, or R 1 and R 2 , taken together with the C═O to which they are bonded, form a cycloaliphatic or nonaromatic heterocyclic ring; and R 3 ′ is an optionally substituted aliphatic, cycloaliphatic, nonaromatic heterocyclic, aryl, heteroaryl, aralkyl, or heteroaralkyl group. [0011] In another embodiment, the invention is directed to a method of forming an iminium intermediate compound represented by structural formula (V): including reacting, in the presence of an acid and superatmospheric CO 2 , a protected amine compound represented by PG—NHR 3 * with a carbonyl compound represented by structural formula (VI): wherein R 1 , R 2 , R 3 , and R 3 ′ and R 3 * each have the values given above, and R 3 * is R 3 or R 3 ′—Nu, wherein Nu is the nucleophile. [0012] The disclosed methods allow the reaction of amines with nucleophiles in green solvents such as CO 2 , including supercritical CO 2 . In particular, the methods can lead to C—N bond formation, for example, the C—N bond formation in the intramolecular cyclization of the Pictet Spengler reaction. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a synthetic scheme for in situ protection of amines and cyclization using the methods of the invention. [0014] FIG. 2 depicts a carbamate synthesis reaction, which is specific embodiment of the invention, and lists various conditions for the carbamate synthesis reaction in Table 1. [0015] FIG. 3 depicts side products from one specific embodiment of the invention, a reaction of amine compound 1 with dimethyl carbonate (DMC) in the presence of scCO 2 (Ar=3,4-dimethoxyphenyl). [0016] FIG. 4 depicts another specific embodiment of the invention, a tetrahydroquinoline synthesis reaction, and lists various conditions for the tetrahydroquinoline synthesis in Table 2. [0017] FIG. 5 is a synthetic scheme for yet another specific embodiment of the invention, synthesis of tetrahydro-β-carbolines at conditions: (a) 5 equiv CO(OBn) 2 , scCO 2 , 130 degrees C., 130 bar, 24 h; (b) add 1.3 equiv aq HCHO, 1.3 equiv 50% aq trifluoracetic acid (TFA), 80 degrees C., 160 bar, 24 h. [0018] FIG. 6 is a picture of a Thar stainless steel view cell reactor that can be employed in the invention. [0019] FIG. 7 is a schematic representation of a reactor that can be employed in the invention. DETAILED DESCRIPTION OF THE INVENTION [0020] The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention. [0021] The claimed reactions of the methods of the invention typically can be conducted in situ in the presence of CO 2 during reactions of the methods of the invention. Typically, the CO 2 is in an amount or partial pressure that is superatmospheric, i.e., an amount or partial pressure greater than that of the atmosphere. Typically, the partial pressure of the CO 2 is greater than 1, 5, 25, 50, or 75 atmospheres (bar). In some embodiments, the partial pressure of CO 2 is between about 80 bar and about 200 bar, more typically between about 90 and 195 bar such as between 95 and 100 bar, between 120 and 130 bar, or between 180 and 190 bar. The temperature can be from about 0 degrees C. to about 300 degrees C., typically from about 50 to about 200 degrees C., more typically from about 100 to about 150 degrees C., or in some embodiments about 130 degrees C. Generally, the CO 2 can be at a temperature and pressure within the supercritical range of its phase diagram. [0022] In some embodiments, the dotted line - - - in the protected amine compound can be a covalent bond, and the protected amine compound and the free amine compound are represented respectively by structural formulas (VII) and (VIII): [0023] In some embodiments, the dotted line - - - in the protected amine compound can be no bond, and the protected amine compound and the free amine compound are represented respectively by structural formulas (IX) and (X): The nucleophile Nu can be any nucleophile that is reactive with an amine, e.g. the protected amine. Typically, Nu can be selected from an optionally substituted alkene, cycloalkene, diene, cyclodiene, aryl, or heteroaryl. [0024] In various embodiments, the iminium compound can be prepared in situ by reacting, in the presence of an acid, a second protected amine compound represented by PG—NHR 3 * with a carbonyl compound represented by structural formulas (VI): [0025] wherein R 3 * is R 3 or R 3 ′—Nu. The acid can be any strong mineral or organic acid that does not otherwise react with the compounds. For example, typical acids include hydrochloric, trifluoroacetic, sulfuric, and the like. [0026] The protecting group PG can be any amine protecting group known to the art, such as a steric protecting group or an electronic protecting group. The protecting group renders the second protected amine less reactive to the CO 2 compared to an unprotected amine represented by H—NHR 3 *. Typically, protecting groups are well known to the art and are given in Greene, Wuts, “Protecting Groups in Organic Synthesis”, the entire teachings of which are incorporated herein by reference. In various embodiments, PG can be selected from optionally substituted alkoxycarbonyl, alkanoyl, aryloxycarbonyl, aroyl, aryl, aralkyl, alkylsilyl, arylsilyl, and aralkylsilyl. [0027] Typically, the second protected amine can be prepared by reacting a precursor of the protecting group with the unprotected amine. In some embodiments, the second protected amine is prepared by reacting an optionally substituted dialkyl carbonate with the unprotected amine. [0028] In various embodiments, the unprotected amine can be represented by R 5 —R 4 —NH 2 , wherein R 4 is an optionally substituted linker selected from one to four membered alkylene or two to four membered heteroalkylene; and R 5 is an optionally substituted ring selected from phenyl, naphthyl, tetrahydronaphthyl, anthracyl, imidazolyl, isoimidazolyl, thienyl, furanyl, pyridyl, pyrimidyl, pyranyl, pyrazolyl, pyrrolyl, pyrazinyl, thiazolyl, isothiazolyl, oxazolyl, isooxazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, tetrazolyl, benzo[1,3]dioxolyl, 2,3-dihydro-benzo[1,4]dioxine, benzopyrimidyl, benzopyrazyl, benzofuranyl, indolyl, benzothienyl, benzoxazolyl, benzoisooxazolyl, benzothiazolyl, benzoisothiazolyl, quinolinyl, isoquinolinyl, benzimidazolyl, tetrahydroquinolinyl, and tetrahydroisoquinolinyl. [0029] In some embodiments, the protected amine compound can be represented by a structural formula selected from: wherein Rings A, B, C, D, E, and F are optionally substituted; R 6 is —H or an optionally substituted aliphatic, cycloaliphatic, nonaromatic heterocyclic, aryl, heteroaryl, aralkyl, or heteroaralkyl group, or an amine protecting group; and PG is an amine protecting group. Examples of PG, R 1 and R 2 are the same as those described above. [0030] In a particular embodiment, PG is alkyloxycarbonyl (e.g. methyloxy carbonyl), aryloxycarbonyl (e.g. benzyloxy carbonyl) or aralkoxycarbonyl. [0031] In another particular embodiment, R 1 is —H. [0032] In yet another particular embodiment, R 2 is —H, phenyl, ethyl, isopropyl, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, or an optionally substituted aliphatic, cycloaliphatic, nonansmatic heterocyclic, aryl, heteroaryl, aralkyl, or heteroaralkyl group. In a more particular embodiment, R 2 is —H, phenyl, C1-C4 alkyl, such as ethyl, propyl (e.g., 2-propyl) or butyl (e.g., n-butyl or 2-butyl), or —CO 2 —C1-C4 alkyl), such as —CO 2 —CH 3 , or —CO 2 —C 2 H 5 [0000] Exemplification [0033] The invention relates to strategies for suppressing reaction between CO 2 and an amine without interfering with the ability of the amine to participate in the desired C—N bond-forming reactions. In some specific embodiments, the disclosed invention is drawn to protecting amines as their less nucleophilic carbamate derivatives are surprisingly inert to CO 2 yet reactive to nucleophiles, e.g., in the Pictet-Spengler heterocyclization reaction (see, for example, J. R. Dunetz, et al. Chem. Comuun., 2005, 4465-4467, the entire teachings of which are incorporated herein by reference). Particularly desirable can be the prospect of converting amine substrates to carbamates in situ, thus utilizing CO 2 as both a reagent and solvent for the reaction. However, alkyl halides and tin reagents can be unattractive from an environmental point of view. It is now found that carbonates such as dimethyl carbonate (DMC) can be employed as a “green methylating agent” for the in situ conversion of amines to methyl carbamates in CO 2 as formulated in eq 3 (R 1 ═Me). [0034] FIG. 1 outlines the application of this synthetic strategy for effecting reactions of amines in CO 2 in the context of the Pictet-Spengler reaction. Reaction of 1 with CO 2 can generate an ammonium carbamate salt, which upon alkylation with DMC can produce the carbamate 7 . Condensation with an aldehyde (in the presence of acid) can then furnish the iminium ion intermediate 8 , which can undergo cyclization to afford the desired Pictet-Spengler product. An added benefit of this approach can be that N-acyliminium ions such as 8 are known to exhibit enhanced reactivity in Pictet-Spengler cyclizations. [0035] Reactions were carried out in a Thar stainless steel view cell reactor (25 mL internal volume) that allows visual inspection via two coaxial sapphire windows. Cell pressure and temperature were monitored with a pressure gauge and internal thermocouple probe. Temperature set-points were achieved using a controller interfaced with insulated heating tape wrapped tightly about the exterior cell wall. Reactor contents were mixed using a magnetic stir bar. [0036] Table 1 of FIG. 2 summarizes the results of optimization of conditions for the in situ generation of carbamates 7 a and 7 b from 1. In a typical reaction, a biphasic system forms consisting of lower density supercritical-like CO 2 phase and a higher density CO 2 -rich liquid phase, the latter containing dialkyl carbonate and the ammonium carbamate salt derived from reaction of 1 with CO 2 . After 24 h at 130° C., complete conversion of 1 was observed leading in quantitative yield to a mixture of 7 a and the side products 10 , 11 , and 12 ( FIG. 3 ). Thus, an issue was to maximize the alkylation of the intermediate carbamate salt 5 (leading to the desired product) relative to the competing N-alkylation of the amine starting material (which was shown to be responsible for the formation of these side products). [0037] The equilibrium formulated in eq 2 is expected to be shifted further toward 5 with an increase in the concentration of CO 2 in the CO 2 -expanded liquid phase, leading to an increase in the selectivity for alkylation of the carbamate salt 5 over alkylation of amine 3. Dimethyl carbonate readily absorbs carbon dioxide, and so an increase in the amount of DMC employed can result in an increase in the amount of CO 2 in the liquid DMC/ammonium carbamate salt phase. This can lead to an increase in selectivity for the desired alkylation, and thus an improved yield of 7 a, as shown in Table 1, entries 1 to 4. The concentration of MeOH byproduct, which was shown to lower the selectivity for carbamate formation, was also reduced when more DMC was employed. Improved yields of 7 a were also observed with increasing CO 2 pressure, which similarly promoted carbamate salt formation via an increase in liquid phase CO 2 concentration (compare entries 2, 5, and 6). It is noteworthy that the selectivity for 7 a decreased at very high pressures (entry 7) where the DMC partitioned from the liquid phase into the blanket scCO 2 phase, resulting in a smaller volume of DMC in the liquid phase (verified visually), and thus a lower concentration of CO 2 in this phase. Selectivity for 7 a over 10 - 12 increased at lower temperatures (entry 8), possibly due to (a) increased absorption of CO 2 into the liquid phase at lower temperatures, and/or (b) slower N-methylation of the amine at temperatures ≦100° C. However, alkylation of the ammonium carbamate salt was also sluggish at 100° C. resulting in incomplete conversion after 24 h. Finally, entry 11 demonstrates that this strategy for the in situ protection of amines in scCO 2 can also be extended to the formation of benzyl carbamates by substituting dibenzyl carbonate (DBC) for DMC. The utility of Cbz derivatives as protective groups for amines is well established. [0038] The in situ generated carbamates were employed as substrates for acyl-Pictet-Spengler reactions in a triphasic system consisting of a supercritical-like CO 2 phase, a CO 2 -rich liquid phase, and a H 2 O-rich liquid phase. Table 2 of FIG. 4 delineates the scope of this two-stage strategy for effecting Pictet-Spengler reactions of β-arylethylamines. Typical conditions involved treating the amine with dialkyl carbonate in scCO 2 at 130° C. (120-130 bar) for 24 h, cooling the resulting reaction mixture to 80° C., and then adding the aldehyde and acid (1.5 equiv) via a pressurized injection loop. Further reaction at 80° C. for 24 h then afforded the desired tetrahydroisoquinolines. Both electron-neutral and electron-rich β-arylethylamines participated in the reaction, which could also be applied to a variety of aliphatic and aromatic aldehydes. Pictet-Spengler reaction with methyl glyoxylate could be achieved by introducing this aldehyde in the form of its dimethyl acetal derivative. Trifluoroacetic acid could be employed in place of H 2 SO 4 to promote iminium ion formation, and its use lead to somewhat improved yields probably due to the sensitivity of some carbamate groups to sulfuric acid under these conditions. Finally it was noted that the overall yield for this two-stage process improves somewhat as the volume of DMC increases from 2.0 to 7.5 equiv relative to amine. It is believed that this effect was attributed to improved selectivity for carbamate formation over N-methylation as discussed above. [0039] FIG. 5 illustrates the extension of the Pictet-Spengler reaction in multiphasic scCO 2 /CO 2 -expanded liquid media to include the synthesis of tetrahydro-β-carbolines. Reaction of tryptamine 22 with CO 2 and DBC afforded 23 which reacted with formaldehyde in the presence of TFA to fumish 24 in 61% overall yield. [0040] In summary, the disclosed methods, employing the in situ conversion of the amine substrate, e.g., β-arylethylamine reactants, to protected derivatives, e.g., carbamate derivatives by reaction with CO 2 and dialkyl carbonates, can effect Pictet-Spengler reactions in multiphasic scCO 2 /CO 2 -expanded liquid media. This general strategy for utilizing amines can be employed in other C—N bond-forming reactions in environmentally-friendly media by employing appropriate substrates and nucleophiles. [0000] General Procedures [0041] All reactions were performed in the 25-mL Thar stainless steel view cell reactor (model 05422-2) shown in FIG. 6 . A schematic flow diagram of the experimental apparatus is in FIG. 7 . This reactor allows visual inspection via two 1-inch coaxial sapphire windows. Cell pressures and temperatures were monitored with a Swagelok industrial pressure gauge (0-350 bar range, accuracy of ±5 bar) and Omega K-type low-noise thermocouple probe (accuracy of ±1° C.). Temperature set-points were attained using an Omega miniature autotune temperature controller in PID mode (series CN9000A) in conjunction with a Powerstat variable autotransformer (type 3PN116B) and Omega insulated heating tape (model# STH051-060) wrapped tightly about the exterior cell wall. The reactor was purged with argon before pressurizing with CO 2 and the reactor contents were mixed using a magnetic stir bar. Reaction product solutions and chromatography fractions were concentrated by rotary evaporation at ca. 20 mmHg and then at ca. 0.1 mmHg (vacuum pump) unless otherwise indicated. Thin layer chromatography was performed on Merck precoated glass-backed silica gel 60 F-254 0.25 mm plates. Column chromatography was performed on EM Science silica gel 60 or Silicycle silica gel 60 (230-400 mesh). [0000] Materials [0042] Commercial grade reagents were used without further purification except as indicated below. Isobutyraldehyde and propionaldehyde were distilled under argon. Carbon dioxide (99.9995%) was purchased from Airgas. Aqueous solutions of H 2 SO4 and TFA were prepared by adding the acid to deionized water. [0000] Instrumentation [0043] The melting points of crystalline products were determined with a Fisher-Johns melting point apparatus and are uncorrected. Infrared spectra were obtained using a Perkin Elmer 2000 FT-IR spectrophotometer. 1 H NMR and 13 C NMR spectra were measured with an Inova 500 spectrometer. 1 H NMR chemical shifts are expressed in parts per million (δ) downfield from tetramethylsilane (with the CHCl 3 peak at 7.27 ppm used as a standard). 13 C NMR chemical shifts are expressed in parts per million (δ) downfield from tetramethylsilane (with the central peak of CHCl 3 at 77.23 ppm used as a standard). Low resolution mass spectra (GC-MS) were measured on a Agilent 6890N series gas chromatograph with Agilent 5973 series mass selective detection. High resolution mass spectra (HRMS) were measured on a Bruker Daltonics APEXII 3 telsa Fourier transform mass spectrometer. [0000] General Procedure A for the Two-Stage Reaction Using Sulfuric Acid to Promote Pictet-Spengler Cyclization. N-(Methoxycarbonyl)-1,2,3,4-Tetrahydroisoquinoline (14) [0044] A 25-mL, stainless steel Thar view cell reactor was charged with phenethylamine (13) (1.6 mL, 1.5 g, 13 mmol) and dimethyl carbonate (2.2 mL, 2.4 g, 26 mmol), pressurized to 50 bar with CO 2 , heated to 130° C., and then pressurized with additional CO 2 to 120 bar. The biphasic reaction mixture was stirred at 130° C. (120-130 bar) for 24 h. The reactor was allowed to cool to 80° C. and formaldehyde (1.5 mL, 13 M in H 2 O, 20 mmol) and H 2 SO 4 (2.0 mL, 9.0 M in H 2 O, 18 mmol) were added sequentially via the 2-mL sample loop (depicted in FIG. 7 as # 9 ). The resulting triphasic reaction mixture was stirred at 80° C. (140-160 bar) for 24 h. The reactor was cooled to room temperature, the CO 2 -phase was sparged into a biphasic mixture containing 15 mL of CH 2 Cl 2 and 15 mL of water, and the remaining reactor contents were dissolved in 100 mL of CH 2 Cl 2 and 100 mL of water. The aqueous layer was separated from the combined organic layers and extracted with three 75-mL portions of CH 2 Cl 2 . The combined organic layers were washed with 150 mL of satd NaCl solution, dried over MgSO 4 , filtered, and concentrated to afford 1.925 g of a dark yellow oil. Column chromatography on 90 g of silica gel (gradient elution with 10-15% EtOAc-hexanes) provided 1.271 g (52%) of tetrahydroisoquinoline 14 as a colorless oil: IR (neat) 2953, 1709, 1605, and 1449 cm −1 ; 1 H NMR ( FIG. 10 ) (500 MHz, CDCl 3 ) δ7.10-7.32 (m, 4H), 4.63 (br s, 2H), 3.76 (s, 3H), 3.70 (m, 2H), and 2.86 (br s, 2H); 13 C NMR (125 MHz, CDCl 3 ) δ156.2, 134.6 (and rotamer 134.8), 133.3 (and rotamer 133.6), 128.8 (and rotamer 129.0), 128.7, 126.5, 126.4 (and rotamer 126.7), 52.9, 45.9, 41.5 (and rotamer 41.7), and 28.9 (and rotamer 29.2); GC-MS m/z: 191 (M + ). [0000] N-(Methoxycarbonyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (15) [0045] Reaction of amine 1 (2.1 mL, 2.3 g, 13 mmol), DMC (2.1 mL, 2.2 g, 25 mmol), formaldehyde (1.5 mL, 13 M in H 2 O, 20 mmol) and H 2 SO 4 (2.0 mL, 9.0 M in H 2 O, 18 mmol) according to General Procedure A afforded 3.291 g of a dark brown oil. Column chromatography on 120 g of silica gel (gradient elution with 5-50% EtOAc-hexanes) provided 1.710 g (54%) of tetrahydroisoquinoline 15 as a colorless oil: IR (neat) 2953, 1710, 1691, 1612, and 1513 cm −1 ; 1 H NMR ( FIG. 11 ) (500 MHz, CDCl 3 ) δ6.61 (s, 1H), 6.58 (m, 1H), 4.54 (br s, 2H), 3.85 (s, 3H), 3.84 (s, 3H), 3.74 (s, 3H), 3.65-3.70 (m, 2H), and 2.76 (br s, 2H); 13 C NMR (125 MHz, CDCl 3 ) δ155.9, 147.53, 147.49, 126.0 (and rotamer 126.3), 124.7 (and rotamer 125.1), 111.3 (and rotamer 111.4), 108.8 (and rotamer 109.0), 55.82, 55.79, 52.5, 45.3, 41.3 (and rotamer 41.5), and 28.1 (and rotamer 28.3); GC-MS m/z: 251 (M + ). [0000] N-(Methoxycarbonyl)-6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydroisoquinoline (16) [0046] Reaction of amine 1 (2.1 mL, 2.3 g, 13 mmol), DMC (2.1 mL, 2.2 g, 25 mmol), benzaldehyde (2.0 mL, 2.1 g, 20 mmol) and H 2 SO 4 (2.0 mL, 9.0 M in H 2 O, 18 mmol) according to General Procedure A afforded 4.150 g of a brown oil. Column chromatography on 140 g of silica gel (elution with 30% EtOAc-hexanes) provided 2.300 g (56%) of tetrahydroisoquinoline 16 as a white solid: mp 98-100° C.; IR (film) 2952, 1703, 1692, 1611, 1515, and 1444 cm −1 ; 1 H NMR ( FIG. 12 ) (500 MHz, CDCl 3 ) δ7.24-7.31 (m, 5H), 6.67 (s, 1H), 6.50 (s, 1H), 6.41 (rotamer, br s, 0.5H), 6.24 (rotamer, br s, 0.5H), 4.15 (rotamer, br s, 0.5H), 4.00 (rotamer, br s, 0.5H), 3.89 (s, 3H), 3.76 (s, 6H), 3.15 (br s, 1H), 2.94 (br s, 1H), 2.69 (rotamer, br s, 0.5H), and 2.66 (rotamer, br s, 0.5H); 13 C NMR (125 MHz, CDCl 3 ) δ156.0, 148.2, 147.6, 142.7, 128.8, 128.7, 128.4, 127.6, 127.1, 111.3, 111.2, 57.3 (and rotamer 57.4), 56.12, 56.06, 52.9, 37.7 (and rotamer 37.9), and 28.0 (and rotamer 28.2); GC-MS m/z: 327 (M + ). [0000] N-(Methoxycarbonyl)-1-isopropyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (17) [0047] Reaction of amine 1(2.1 mL, 2.3 g, 13 mmol), DMC (2.1 mL, 2.2 g, 25 mmol), isobutyraldehyde (1.7 mL, 1.3 g, 19 mmol) and H 2 SO 4 (2.0 mL, 9.0 M in H 2 O, 18 mmol) according to General Procedure A afforded 2.882 g of a dark orange oil. Column chromatography on 160 g of silica gel (gradient elution with 20-30% EtOAc-hexanes) provided 1.975 g (53%) of tetrahydroisoquinoline 17 as a colorless oil: IR (neat) 2958, 1698, 1611, 1518, and 1446 cm −1 ; 1 H NMR ( FIG. 13 ) (500 MHz, CDCl 3 ) δ6.52-6.56 (m, 2H), 4.70 (rotamer, d, J=8.5 Hz, 0.5H), 4.57 (rotamer, d, J=8.5 Hz, 0.5H), 4.02 (rotamer, app quint, J=6.1 Hz, 0.5H), 3.76 (s, 6H), 3.61 (s, 3H), 3.38 (rotamer, dt, J=13.0, 6.9 Hz, 0.5H), 3.29 (rotamer, ddd, J=5.8, 8.9, 13.1 Hz, 0.5H), 2.78 (m, 0.5H), 2.66-2.71 (m, 2H), 1.92 (m, 1H), and 0.84-0.91 (m, 6H); 13 C NMR (125 MHz, CDCl 3 ) δ156.3 (and rotamer 156.6), 147.5 (and rotamer 147.6), 146.49 (and rotamer 146.53), 128.5 (and rotamer 129.0), 126.1 (and rotamer 126.3), 111.3 (and rotamer 111.4), 111.0 (and rotamer 111.1), 60.1 (and rotamer 60.2), 55.79 (and rotamer 55.83), 55.7, 52.3 (and rotamer 52.4), 39.0 (and rotamer 39.5), 33.77 (and rotamer 33.81), 27.1 (and rotamer 27.4), 20.1 (and rotamer 20.2), and 19.5 (and rotamer 19.6); GC-MS m/z: 293 (M + ). [0000] N-(Methoxycarbonyl)-6,7-dimethoxy-1-methoxycarbonyl-1,2,3,4-tetrahydroisoquinoline (18) [0048] Reaction of amine 1 (2.1 mL, 2.3 g, 13 mmol), DMC (2.1 mL, 2.2 g, 25 mmol), methyl dimethoxyacetate (2.3 mL, 2.5 g, 19 mmol) and H 2 SO 4 (2.0 mL, 9.0 M in H 2 O, 18 mmol) according to General Procedure A afforded 2.910 g of a dark red oil. Column chromatography on 140 g of silica gel (gradient elution with 30-35% EtOAc-hexanes) provided 1.901 g (49%) of tetrahydroisoquinoline 18 as a colorless oil: IR (neat) 2954, 1744, 1699, 1611, 1520, and 1447 cm −1 ; 1 H NMR ( FIG. 15 ) (500 MHz, CDCl 3 ) δ6.98 (rotamer, s, 0.5H), 6.96 (rotamer, s, 0.5H), 6.62 (s, 1H), 5.54 (rotamer, s, 0.5H), 5.47 (rotamer, s, 0.5H), 4.00 (rotamer, dt, J=12.5, 5.5 Hz, 0.5H), 3.87 (s, 3H), 3.85 (s, 3H), 3.80 (rotamer, m, 0.5H), 3.76 (rotamer, s, 1.5H), 3.75 (rotamer, m, 0.5H), 3.74 (rotamer, s, 1.5H), 3.72 (rotamer, s, 1.5H), 3.71 (rotamer, s, 1.5H), 3.67 (rotamer, m, 0.5H), and 2.76-2.86 (m, 2H); 13 C NMR (125 MHz, CDCl 3 ) δ171.8, 156.0 (and rotamer 156.6), 148.66 (and rotamer 148.70), 147.66 (and rotamer 147.69), 127.3 (and rotamer 127.5), 121.6 (and rotamer 122.1), 111.0 (and rotamer 111.2), 110.6 (and rotamer 110.8), 57.5 (and rotamer 57.6), 56.1, 55.9, 53.0 (and rotamer 53.1), 52.56 (and rotamer 52.59), 40.2 (and rotamer 40.5), and 28.0 (and 28.2); GC-MS m/z: 309 (M + ). [0000] General Procedure B for the Two-Stage Reaction Using Trifluoroacetic Acid to Promote Pictet-Spengler Cyclization. N-(Carbobenzyloxy)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (19) [0049] A 25-mL, stainless steel Thar view cell reactor was charged with amine 1 (2.1 mL, 2.3 g, 13 mmol) and dibenzyl carbonate (5.3 mL, 6.2 g, 26 mmol), pressurized to 50 bar with CO 2 , heated to 130° C., and then pressurized with additional CO 2 to 120 bar. The biphasic reaction mixture was stirred at 130° C. (120-130 bar) for 24 h. The reactor was allowed to cool to 80° C. and formaldehyde (1.5 mL, 13 M in H 2 O, 20 mmol) and trifluoroacetic acid (3.0 mL, 50% v/v in H 2 O, 19 mmol) were added sequentially via the 3-mL sample loop (depicted in FIG. 7 as # 9 ). The resulting triphasic reaction mixture was stirred at 80° C. (140-160 bar) for 24 h. The reactor was cooled to rt, the CO 2 -phase was sparged into a biphasic mixture containing 15 mL of CH 2 Cl 2 and 15 mL of water, and the remaining reactor contents were dissolved in 100 mL of CH 2 Cl 2 and 100 mL of water. The combined organic and aqueous layers were washed with 100 mL of 1 M NaOH solution, and the aqueous layer was separated and extracted with four 75-mL portions of CH 2 Cl 2 . The combined organic layers were washed with 200 mL of satd NaCl solution, dried over MgSO 4 , filtered, and concentrated to afford 8.528 g of a dark yellow oil. Column chromatography on 160 g of silica gel (gradient elution with 20-30% EtOAc-hexanes) provided 2.755 g (67%) of tetrahydroisoquinoline 19 as a colorless oil: IR (neat) 2935, 1703, 1692, 1611, 1517, and 1427 cm −1 ; 1 H NMR ( FIG. 16 ) (500 MHz, CDCl 3 ) δ7.25-7.36 (m, 5H), 6.58 (s, 1H), 6.56 (rotamer, br s, 0.5H), 6.51 (rotamer, br s, 0.5H), 5.15 (s, 2H), 4.54 (s, 2H), 3.79 (s, 3H), 3.78 (s, 3H), 3.67 (m, 2H), and 2.72 (m, 2 H); 13 C NMR (125 MHz, CDCl 3 ) δ155.1 (and rotamer 155.2), 147.42, 147.37, 136.5, 128.3, 127.8, 127.6, 125.9 (and rotamer 126.1), 124.4 (and rotamer 125.0), 111.2 (and rotamer 111.3), 108.7 (and rotamer 108.9), 66.8 (and rotamer 66.9), 55.64, 55.63, 45.1 (and rotamer 45.3), 41.2 (and rotamer 41.5), and 28.0 (and rotamer 28.2); HRMS-ESI m/z: [M+Na] + calcd for C 19 H 21 NO 4 , 350.1363; found, 350.1360. [0000] N-(Carbobenzyloxy)-1-ethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (20) [0050] Reaction of amine 1 (2.1 mL, 2.3 g, 13 mmol), DBC (5.3 mL, 6.2 g, 26 mmol), propionaldehyde (1.4 mL, 1.1 g, 19 mmol) and TFA (3.0 mL, 50% v/v in H 2 O, 19 mmol) according to General Procedure B afforded 8.890 g of an orange oil. Column chromatography on 140 g of silica gel (gradient elution with 10-30% EtOAc-hexanes) provided 3.173 g (71%) of tetrahydroisoquinoline 20 as a colorless oil: IR (neat) 2963, 1693, 1611, 1519, and 1427 cm −1 ; 1 H NMR ( FIG. 17 ) (500 MHz, CDCl 3 ) δ7.33-7.38 (m, 5H), 6.62 (rotamer, s, 0.5H), 6.60 (rotamer, s, 0.5H), 6.58 (rotamer, s, 0.5H), 6.56 (rotamer, s, 0.5H), 5.23 (rotamer, d,J=12.5 Hz, 0.5H), 5.18 (rotamer, s, 1H), 5.09 (rotamer, d, J=12.5 Hz, 0.5H), 5.07 (rotamer, t, J=7.3 Hz, 0.5H), 4.97 (rotamer, t, J=7.3 Hz, 0.5H), 4.28 (rotamer, m, 0.5H), 4.09 (rotamer, m, 0.5H), 3.86 (s, 6H), 3.33 (rotamer, m, 0.5H), 3.22 (rotamer, m, 0.5H), 2.93 (rotamer, m, 0.5H), 2.85 (rotamer, m, 0.5H), 2.67 (rotamer, m, 0.5H), 2.64 (rotamer, m, 0.5H), 1.80 (m, 2H), 1.00 (rotamer, t, J=7.3 Hz, 1.5H), and 0.96 (rotamer, t, J=7.3 Hz, 1.5H); 13 C NMR (125 MHz, CDCl 3 ) δ155.2, 147.2 (and rotamer 147.3), 147.0, 136.4 (and rotamer 136.6), 129.2 (and rotamer 129.5), 128.0, 127.48 (and rotamer 127.6), 127.3 (and rotamer 127.55), 125.3 (and rotamer 125.5), 111.0 (and rotamer 111.2), 109.5 (and rotamer 109.8), 66.5 (and rotamer 66.8), 55.5, 55.4, 55.3, 37.0 (and rotamer 37.7), 29.2 (and rotamer 29.4), 27.4 (and rotamer 27.8), and 10.68 (and rotamer 10.72); HRMS-ESI m/z: [M+Na] + calcd for C 21 H 25 NO 4 , 378.1676; found, 378.1666. [0000] N-(Carbobenzyloxy)-6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydroisoquinoline (21) [0051] Reaction of amine 1 (2.1 mL, 2.3 g, 13 mmol), DBC (5.3 mL, 6.2 g, 26 mmol), benzaldehyde (2.0 mL, 2.1 g, 18 mmol) and H 2 SO 4 (2.0 mL, 9.0 M in H 2 O, 18 mmol) according to General Procedure A afforded 8.960 g of an orange oil. Column chromatography on 100 g of silica gel (gradient elution with 5-30% EtOAc-hexanes) provided 2.882 g (57%) of tetrahydroisoquinoline 21 as a very pale yellow oil: IR (neat) 2935, 1693, 1611, 1517, and 1425 cm −1 ; 1 H NMR (500 MHz, CDCl 3 ) δ7.17-7.40 (m, 10H), 6.68 (s, 1H), 6.53 (s, 1H), 6.45 (rotamer, br s, 0.5H), 6.26 (rotamer, br s, 0.5H), 5.22-5.30 (m, 1H), 5.18 (rotamer, s, 0.5H), 5.16 (rotamer, s, 0.5H), 4.20 (rotamer, br s, 0.5H), 4.07 (rotamer, br s, 0.5H), 3.90 (s, 3H), 3.76 (s, 3H), 3.19 (br s, 1H), 2.96 (br s, 1H), and 2.69 (br s, 1H); 13 C NMR (125 MHz, CDCl 3 ) δ154.9 (and rotamer 155.3), 147.9, 147.4, 142.4, 136.6, 128.5, 128.4, 128.3, 128.2, 127.7 (and rotamer 127.9), 127.4, 127.0, 126.7 (and rotamer 126.8), 126.6, 110.9 (and rotamer 111.2), 67.1 (and rotamer 67.4), 57.1 (and rotamer 57.3), 55.8, 55.7, 37.6 (and rotamer 37.8), and 27.8 (and rotamer 28.0); HRMS-ESI m/z: [M+Na] + calcd for C 25 H 25 NO 4 , 426.1676; found, 426.1683. [0000] 2 -(Carbobenzyloxy)-9-(p-toluenesulfonyl)-1,2,3,4-tetrahydro-β-carboline (24) [0052] A 25-mL, stainless steel Thar view cell reactor was charged with tryptamine 22 (0.798 g, 2.54 mmol) and DBC (2.7 mL, 3.2 g, 13 mmol), pressurized to 50 bar with CO 2 , heated to 130° C., and then pressurized with additional CO 2 to 130 bar. The biphasic reaction mixture was stirred at 130° C. (130 bar) for 24 h. The reactor was allowed to cool to 80° C. and formaldehyde (0.50 mL, 6.8 M in H 2 O, 3.4 mmol) and TFA (0.50 mL, 50% v/v in H 2 O, 3.2 mmol) were added sequentially via the 0.50-mL sample loop (depicted in FIG. 7 as # 9 ). The resulting triphasic reaction mixture was stirred at 80° C. (160 bar) for 24 h. The reactor was cooled to rt, the CO 2 -phase was sparged into a biphasic mixture containing 15 mL of CH 2 Cl 2 and 15 mL of water, and the remaining reactor contents were dissolved in 100 mL of CH 2 Cl 2 and 50 mL of water. The combined organic and aqueous layers were washed with 50 mL of satd NaHCO 3 solution, and the aqueous layer was separated and extracted with three 50-mL portions of CH 2 Cl 2 . The combined organic layers were dried over MgSO 4 , filtered, and concentrated to afford 4.116 g of a yellow oil. Two successive purifications by column chromatography on 120 g of silica gel (5-20% EtOAc-hexanes) provided 0.715 g (61%) of tetrahydro-β-carboline 24 as a white solid: mp 52-55° C.; IR (film) 2922, 1704, 1597, 1426, 1366, and 1232 cm −1 ; 1 H NMR ( FIG. 18 ) (500 MHz, CDCl 3 ) 58.16 (d, J=8.2 Hz, 1H), 7.79 (m, 1H), 7.64 (m, 1H), 7.32-7.44 (m, 7H), 7.21-7.28 (m, 2H), 7.02 (m, 1H), 5.23 (s, 2H), 5.02 (br s, 2H), 3.81 (br s, 2H), 2.73 (br s, 2H), 2.33 (rotamer, s, 1H), and 2.30 (rotamer, s, 2H); 13 C NMR (125 MHz, CDCl 3 ) δ155.6 (and rotamer 155.7), 145.1, 136.7, 135.5 (and rotamer 136.2), 131.0 (and rotamer 131.6), 130.1, 129.6, 128.7, 128.3, 128.1, 126.5 (and rotamer 126.7), 124.7 (and rotamer 124.8), 123.6 (and rotamer 123.7), 118.4 (and rotamer 118.5), 117.1 (and rotamer 117.8), 114.4, 67.6, 43.5 (and rotamer 43.8), 41.2 (and rotamer 41.4), 21.7, and 21.2; HRMS-ESI m/z: [M+Na] + calcd for C 26 H 24 N 2 O 4 S, 483.1349; found, 483.1355. EQUIVALENTS [0053] 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.	A method includes preparing a protected amine compound represented by the following structural formula: wherein the dotted line - - - is a covalent bond or no bond. The method includes the step of, in the presence of superatmospheric CO 2 : a) intermolecularly reacting an iminium compound with a nucleophile Nu represented by the following structural diagram: or b) intramolecularly reacting an iminium group of an iminium compound represented by the following structural formula, the iminium compound having a nucleophile: with the nucleophile of the iminium compound, thereby forming the protected amine compound.	2
This application claims the benefit of Provisional application Ser. No. 60/225,159, filed Aug. 14, 2000. BACKGROUND OF THE INVENTION A number of potential advantages have led the automotive industry to look with increasing interest toward utilizing common rail (manifold) high pressure direct injection for gasoline engines. A number of design constraints or difficulties seem to stand in the way of fully achieving the advantages. The pressurization of fuel to high levels (e.g., above 100 bar) requires considerable pumping power, which generates considerable heat. Moreover, the industry is looking for even higher rail pressures, above 200 bar. This heat could be dissipated to a large extent, if all the fuel that is pressurized, can be quickly injected into the engine cylinders. This is not possible, however, because the fuel pump flow rate is typically sized for engine cranking, which may be at 20-30 bar pressure at a high quantity discharge flow rate, whereas typical steady state cruising conditions require much lower quantity flow rates at 100 bar. Therefore, in a conventional pumping scheme, the volume of fuel raised to injection pressure during the course of an hour of typical vehicle use, is much greater than the volume of fuel actually injected during that same hour of use. Although pre-metering and various spill control techniques can be used to some advantage in this regard, none of these techniques satisfactorily regulates the power output of the high pressure pump itself. Another difficulty is encountered with high pressure pumps that are driven directly by the engine (e.g., crank shaft, cam shaft, accessory belt). During transients when fuel demand is low (e.g., downhill or during gear shifting), the engine continues to turn and the, pump continues to deliver high pressure fuel to the common rail that may already be at maximum pressure. SUMMARY OF THE INVENTION It is an object of the present invention to provide a high pressure gasoline common rail direct injection fuel supply system, in which the high pressure discharge of the pump for raising and maintaining the rail pressure above 100 bar, is responsive to engine demand. The energy imparted to the discharged fuel (e.g., pressure increase) is over time, significantly reduced relative to conventional systems. According to the invention, a high pressure rotary pump is coupled to the engine with a magnetic clutch which may also serve as a motorized drive. The speed of the pump can be controlled by the degree of slippage of the clutch, which is responsive to the rail pressure. The clutch can quickly increase the pump drive shaft speed by reducing slippage and thus provide high pumping volume during cranking, while reducing speed to a low level by slippage with associated low pumping volume when the vehicle is cruising. Similarly, the clutch can intermittently increase speed as needed to accommodate load demand during acceleration or, in essence, stop the pump drive when the vehicle is coasting. In a particularly noteworthy aspect, the clutch is arranged and controllable so that the clutch can include a “motorizing” feature, which can be used to increase the speed of the pump during cranking when the pump speed would otherwise be slower than desired. The invention also provides for the positive sealing of the pump by an isolation barrier. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partially in cross section of a fuel pump driven by a magnetic clutch attached to a rotating shaft of an engine with the fuel pump discharging into a common fuel injection rail with the clutch controlling the rail pressure. FIG. 2 diagrammatically illustrates a face view of the arrangement of coils and permanent magnets for the version of the invention shown in FIG. 1 . FIG. 3 is a view similar to FIG. 1 showing another embodiment of the clutch arrangement. FIG. 4 diagrammatically illustrates a face view of the arrangement of coils and permanent magnets for the version of the invention shown in FIG. 3 . FIG. 5 is a schematic of the controller and electrical connections to the clutch for controlling the slippage of the clutch. FIGS. 6 and 7 are charts illustrating the on-off cycles for the coils over time to control the slippage with FIG. 6 producing more slippage and low output and FIG. 7 producing less slippage and higher FIG. 8 is a schematic of the controller and electrical connections to the coils for the motorizing function. FIG. 9 is a chart illustrating the on-off cycles for the coils in the motorized operation of the clutch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT According to the invention, as first exemplified in FIG. 1 , an engine mounted fuel injection pump generally designated 10 is driven by any rotating shaft of the engine, for example a camshaft, crank shaft, or engine accessory shaft. However, rather than being transferred directly, the power is transferred from the engine to the pump by a magnetic clutch. Magnetic clutches are used in various industries to control slippage between the input and output shaft at more or less constant torque. The magnetic clutch consists of two rotating members, a drum with magnetic coils mounted on the torque input shaft and a rotor with permanent magnets mounted on the torque output shaft. As shown in FIG. 1 , the torque input shaft 12 is an engine camshaft, whereas the torque output shaft 14 is the pump shaft (usually an eccentric shaft) of a typical radially reciprocating, multi-plunger gasoline direct injection pump of known construction. Again referring to FIG. 1 , a portion 16 of an engine houses the camshaft 12 . Mounted onto the end of the camshaft 12 is a drum 18 with a series of electromagnetic coils 20 each connected to the slip rings 22 , 23 and 24 . The slip rings are contacted by the brushes 26 which are connected into the controller 28 as will be discussed further below. During cranking, the coils 20 produce a rotating magnetic field which is used to drive the output shaft 14 of the pump 10 . Rigidly mounted on the output shaft 14 is a rotor comprising the hub 30 and support disk 32 on which are mounted the permanent magnets 34 . Torque is transmitted from the camshaft 12 by the magnetic coils 20 to the permanent magnets 34 and then to the output shaft 14 . FIG. 2 is a diagram illustrating the relationship of the coils 20 and permanent magnets 34 . Since the energy transmitting components (the magnetic coils and the permanent magnets) are substantially annular and face each other in the axial direction with an air gap separation, some axial forces are generated which are supported by drive shaft bearings 36 and pump bearings 38 . However, this configuration permits the use of a relatively simple isolation barrier 40 between the input side comprising the camshaft 12 , drum 18 and magnetic coils 20 and the output side comprising the pump and including the hub 30 , support disk 32 and permanent magnets 34 . With this arrangement, the isolation barrier 40 is a simple flat plate or diaphragm usually of stainless steel where all radial forces are balanced and mechanical axial forces are absent. There will, however, be an axial force component acting on the positive pressure barrier 40 originating from hydraulic pressure in the pump housing. This axial force needs to be considered in the dimensioning and design of the barrier 40 and especially its minimum thickness. The thickness of the barrier 40 affects the size of the air gap between the coils and magnets, and by that, also the efficiency of the clutch. In order to reduce the hydraulic pressure in the pump housing, it is possible to provide separate inlet and outlet check valves located in the hydraulic head and allow the hydraulic pressure in the housing to be reduced to a lower level. This would require a leak-off line which is not shown. FIGS. 3 and 4 of the drawings illustrate another embodiment of the invention. In this embodiment, the energy-transmitting components are closely spaced apart radially rather than being axially arranged as in FIGS. 1 and 2 . Specifically, the plurality of coils 42 are now mounted around the periphery of a rotor 44 with the rotor 44 also incorporating the slip rings 46 , 48 and 50 contacted by the brushes 51 . Although the minimum of three brushes and three slip rings are illustrated as well as three coils and four permanent magnets, the number of coils and/or permanent magnets can be varied to produce the desired clutch and motorizing functions for any particular situation. The rotor 44 , which is partially enclosed in the housing segment 52 , is both supported and driven by the extension 54 of the driving (cam) shaft 12 which is inserted into the central opening in the rotor 44 . In this embodiment of the invention, the plurality of permanent magnets 56 are mounted on the support member 58 which is attached to the hub 30 much like the support disk 32 in FIG. 1 . The support member 58 has an outer peripheral edge or flange 60 shaped to surround the coils 42 . The permanent magnets 56 are mounted on this peripheral edge 60 such that they are directly radially outward from the coils 42 . Mounted between the input side of the clutch with the drive shaft 12 , rotor 44 and coils 42 and the output side with the pump and including the hub 30 , the support member 58 and the permanent magnets 56 is the isolation barrier 62 . The isolation barrier 62 is now cup shaped such that it extends between the coils 42 and the radially outward permanent magnets 56 . Since the magnetic forces are now radial instead of axial, the bearing 64 supporting the pump shaft 14 does not need to accommodate axial forces. The clutch slippage is regulated by the same controller 28 as in FIG. 1 . Because there is no physical contact between the input and output shafts 12 and 14 , the entire drive portion of the pumping component is hermetically sealed by the isolation barrier 40 or 62 and no shaft seals are needed. The absence of a shaft seal reduces friction losses, reduces heat rejection and drive power requirement, and also assures higher reliability by avoiding wear of the sealing components. It is also very likely that the total cost of such a system is very competitive. As indicated earlier, the fuel injection pump 10 is connected at 66 to the common rail or manifold 68 of the fuel injection system as shown in FIG. 1 . The fuel injectors themselves would be connected into the rail 68 . Mounted on the rail 68 is a pressure transducer 70 which is connected by the line 72 to the previously mentioned controller 28 . In a typical industrial application, the reference feedback for a magnetic clutch is provided by a tachometer mounted on the output shaft. In the present invention, the actual pressure in the rail 68 is used as the reference feedback. The controller 28 modulates the application of power to the coils of the clutch in response to the rail pressure. That is, the current to the coils is turned on and off to vary the pulse width and control the amount of slippage. FIG. 5 is a schematic illustrating the connection of the coils 20 (or 42 ) to the controller 28 for the control of slippage. For this function, the switches 74 in the controller operate simultaneously. In FIG. 5 , they are all shown as being open. The amount of slippage in the clutch is controlled by the ratio of the amount of time the switches are closed (power applied to coils) compared to the amount of time the switches are open. This is illustrated in FIGS. 6 and 7 with FIG. 6 illustrating short applications of power to the coils (short pulse width) resulting in greater slippage and lower output and FIG. 7 illustrating longer applications of power (long pulse width) and less slippage and greater output. This closed loop mode of operation permits regulation accuracy within 0.5% to 1%. Magnetic clutches commonly have a 34:1 speed range and, during a short period of time can transmit up to 250% of the rated torque. The torque transmission is very energy efficient and the power to the coils is only about 10% of the total drive power requirement. A magnetic clutch unit can be purchased commercially, rated for 24V and capable of transmitting 108 Ncm torque at speeds between 50 RPM and 3300 RPM, at a global efficiency of 91% (electric motor and clutch). This compares very favorably with the expected losses of, for example, up to 50% with a solenoid valve demand controlled gasoline pump. Another advantage is that because the clutch can be deliberately overloaded up to 100% for a short time period (for example, during transient operation), the clutch can be relatively undersized. As a result, the heat rejection during the normal operation can be minimized. As the internal magnetic clutch components are very similar to the components of a stepper motor or a brushless electric motor, the clutch can be designed and the driving function can be expanded in such a way as to provide a “motorizing feature” for the clutch output shaft. This means that the clutch output shaft can be forced to rotate by an induced rotating magnetic field even before the engine starter begins to spin. This results in a very rapid pressure build up during cranking, which is a very desirable feature. Even with a modest motorizing capability of, for example, a maximum achievable speed of 1000 RPM, it could be used to enhance transient operation of a generally undersized pump. Referring to FIG. 8 , the switches 74 are now closed and opened sequentially to produce the rotating magnetic field and cause the permanent magnets to rotate even when the input shaft 12 has not yet rotated. The time line application of power to the coils is illustrated in FIG. 9 .	A pump ( 10 ) of high pressure direct injection fuel supply system is connected to the engine through a magnetic clutch which includes a motorizing function. The magnetic clutch comprises rotating electromagnetic coils ( 20 ) attached to and driven by the engine and rotating permanent magnets ( 34 ) attached to and driving the pump. The slippage of the clutch is controlled by the on-off cycle of electrical power which is simultaneously supplied to all of the electromagnetic coils and may be responsive to the pressure in the fuel injections rail. The clutch may be operated as an electrical motor by sequentially activating the electromagnetic coils for the purpose of providing fuel pressure even prior to rotation or cranking of the engine. An isolation barrier hermetically seals the fuel injection pump from the engine.	5
The United States of America may have certain rights to this invention under Management and Operating contract No. DE-AC05-84ER 40150 from the Department of Energy. FIELD OF THE INVENTION This invention relates to beam position detectors and specifically to an apparatus and method for measuring the position, size, shape, and intensity of a particle beam in a particle accelerator or light-generating device. BACKGROUND OF THE INVENTION When studying the behavior of charged particles at relativistic speeds, such as in particle accelerators, it is necessary and advantageous to measure the properties of the charged particle beam, including beam position, size, shape, and intensity. In a particle accelerator, this task becomes extremely challenging in those areas that have poor beam quality, such as in the vicinity of power beam dumps, which absorb the beam after it has been utilized in experimental targets or material treatment facilities. In these areas, as a result of the particle beam being dispersed by the targets or the treated materials, the quality of the beam is typically very poor. The beam is typically degraded in both the transverse direction and in its time radio frequency (RF) structure. In addition, the areas close to the beam dumps typically experience very high ionizing radiation dose rates from the dumps, and any equipment positioned there must be extremely resistant to radiation damage. Several U.S. patents disclose apparatus and methods for measuring various properties of particle beams. However, each of these prior art patents either need good RF quality of the beam and small aperture, or need to implement moving parts and respective control systems that are difficult to maintain in working condition in the high radiation environment. Therefore, what is needed is an apparatus and method for measuring the properties of a charged particle beam in high radiation areas and in areas in which the beam quality is poor. SUMMARY OF THE INVENTION The invention is a beam position detector for measuring the properties of a charged particle beam, including the beam's position, size, shape, and intensity. The beam position detector includes one or more absorbers constructed of thermo-resistive material and positioned to intercept and absorb a portion of the incoming beam power. Absorbing a portion of the incoming beam power causes local heating of each absorber. The local temperature increase distribution across the absorber, or the distribution between different absorbers, will depend on the intensity, size, and position of the beam. By constructing the absorbers of a material having a strong dependence of electrical resistivity on temperature and measuring the electrical resistance distribution across the absorber or between different absorbers, a beam position detector is constructed that is capable of measuring beam properties such as beam position, size, shape, and intensity. The absorbers are preferably in the form of rectangular plates or wires constructed of chemical vapor deposition silicon carbide. OBJECTS AND ADVANTAGES The beam position detector of the present invention provides a method of measuring particle beam properties in areas in which the quality of the beam is very poor, such as in the vicinity of beam dumps. In these areas the beam is dispersed in both the transverse direction and in its time RF structure and present methods of beam property measurement are inadequate to properly monitor the beam. A further advantage of the beam position detector of the present invention is that it is highly resistant to radiation damage, and therefore may be used in areas, which exhibit very high ionizing radiation dose rates. Another advantage of the beam position detector of the present invention is that it does not employ any moving parts, which would be difficult to maintain in an area susceptible to high ionizing radiation dose rates. These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings. DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a preferred embodiment of a Beam Position Detector (BPD) according to the present invention using two resistive absorbers. FIG. 2 is a schematic depicting the wiring connections for a voltage measurement across each of the absorbers of FIG. 1 . FIG. 3 is a schematic depicting the wiring connections for a current measurement at each end of one of the absorbers of FIG. 1 . FIG. 4 is a plot of X BPM , the beam x-coordinate extrapolated from a conventional beam position monitor (BPM) and projected to the position of the BPD, versus time during calibration of the beam position detector of FIG. 1 . FIG. 5 is a plot of X BPD , beam x-coordinate calculated using the balance of currents from the beam position detector (BPD) of FIG. 1 , versus time during calibration. FIG. 6 is a scatter plot of X BPD versus X BPM . FIG. 7 is a plot of Y BPM , the beam y-coordinate extrapolated from a conventional beam position monitor and projected to the position of the BPD, versus time during calibration of the beam position detector of FIG. 1 . FIG. 8 is a plot of Y BPD , beam y-coordinate calculated using the balance of currents from the beam position detector of FIG. 1 , versus time during calibration. FIG. 9 is a scatter plot of Y BPD versus Y BPM . FIG. 10 is a perspective view of an alternate embodiment of a beam position detector according to the present invention using four resistive absorbers. FIG. 11 is a perspective view of another alternate embodiment of a beam position detector for providing more detailed information on the beam size and profile by the use of sets of thin parallel metallic conductors deposited on the plates. TABLE OF NOMENCLATURE The following is a listing of part numbers used in the drawings along with a brief description: Part Number Description 20 beam position detector 22 first absorber 22A first end on first absorber 22B second end on first absorber 24 second absorber 24A first end on second absorber 24B second end on second absorber 26 beam path 30 first current monitor 32 second current monitor 34 third current monitor 36 fourth current monitor 38 first voltage monitor 40 second voltage monitor 42 electrical leads to first absorber 44 electrical leads to second absorber 50 beam position detector (first alternate embodiment) 52 metallic conductor 60 beam position detector (second alternate embodiment) 62 first vertical absorber 64 second vertical absorber 66 first horizontal absorber 68 second horizontal absorber A current monitor or ammeter V voltage monitor or voltmeter DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a beam position detector for measuring the position, size, shape, and intensity of a charged particle beam. With reference to FIG. 1 , the beam position detector 20 includes a first absorber 22 and a second absorber 24 positioned to intercept the incoming beam path 26 . The absorbers 22 , 24 may be in the form of plates, as shown in FIG. 1 , or wires. The first absorber 22 is positioned vertically and orthogonal with respect to the path 26 . The second absorber 24 is placed farther down the beam path 26 and is positioned horizontally and orthogonal with respect to the path 26 . Each absorber 22 , 24 has ends including ends 22 A and 22 B on the first absorber 22 and ends 24 A and 24 B on the second absorber 24 . The beam position detector 20 includes a current monitor A at the ends of each of the absorbers 22 , 24 . A first current monitor 30 measures the current at the first end 22 A of absorber 22 and a second current monitor 32 measures the current at the second end 22 B of absorber 22 . A third current monitor 34 measures the current at the first end 24 A of absorber 24 and a fourth current monitor 36 measures the current at the second end 24 B of absorber 24 . Voltage meters V measure the voltage across each of the absorbers, including a first voltage monitor 38 measuring the voltage across absorber 22 and a second voltage monitor 40 measuring the voltage across absorber 24 . To charge the plates preferably one of the absorbers 22 , 24 is biased with a positive voltage relative to the ground and the other absorbers is biased with a negative voltage relative to the ground to create a low-voltage difference between the plates. For the purposes of calibration and data gathering, a voltage of +3 volts was applied to the electrical leads 42 to the first absorber 22 and a voltage of −3 volts was applied to the electrical leads 44 to the second absorber 24 . In this preferred embodiment, the plates 22 , 24 are immersed in the gas atmosphere, preferably an inert gas such as helium. The intensive particle beam crossing the space between the plates 22 , 24 ionizes the gas, thus producing a conductivity path between the plates. The applied potential difference between the plates causes electric current to flow in the space region between the plates traversed by the beam. Depending on the beam transverse coordinates, the balance of the horizontal and vertical currents read from the plates will correspond to the position of beam center. The beam position detector 20 collects and processes the information from each of the current monitors 30 , 32 , 34 , 36 and each of the voltage monitors 38 , 40 . In an especially preferred method of viewing the output of the beam position detector 20 , a microprocessor is used to convert the outputs of the current and voltage monitors to a representation of the position of the particle beam path 26 on a two-coordinate grid. In an alternate embodiment, the beam position can be determined even if the plates are immersed in a vacuum. Referring to the schematics of FIGS. 2 and 3 , the voltage is measured across the absorbers 22 , 24 and the current is measured at the ends of the absorbers 22 , 24 . The voltage meters 38 , 40 measure the electric potential generated in each plate 22 , 24 in the presence of a temperature gradient caused by the incident particle beam 26 . The voltage readout shows a good correlation with the beam position at each plate 22 , 24 . The balance of the currents are read at the plate corners to characterize the beam position. FIG. 3 depicts the second absorber 24 with current monitors 34 , 36 at the two ends 24 A and 24 B. Electrons are knocked out of the plates at a given rate depending on the beam current. This rate is typically 10 nA per 1 μA beam. The currents are all equal to zero when there is no beam incident upon the plates. The currents are all non-zero and equal if the beam striking the plates is small and symmetrical and hits exactly at the middle of the plates. When the beam moves toward one end of a plate, the current readings increase from that end of the plate and decrease at the opposite end of the plate. By monitoring the balance of currents read at the plate ends, the beam position can be measured. Referring to FIG. 1 , two currents 13 , 14 , are read from the ends 22 A, 22 B of the first or vertical absorber 22 , two currents 11 , 12 , are read from the ends 24 A, 24 B of the second or horizontal absorber 24 , and one voltage across each absorber for a total of 6 readings in all. The vertical 22 and horizontal 24 absorbers are biased plus or minus 3 volts relative to the ground to create a low-voltage difference between the plates. Beam ionization in helium gas creates an electrical “short” between the plates, allowing the coordinate readout. Balances of currents from the ends of the vertical 22 and horizontal 24 plates determine the coordinates. Mathematically, in the first approximation, the x and y coordinates are determined by the following formulas: X=C x ( I 1 −I 2 )/( I 1 +I 2 ) (1) Y=C y ( I 3 −I 4 )/( I 3 +I 4 ) (2) where I 1 , and I 2 are the currents read at the ends of the vertical absorber 22 , I 3 and I 4 are the currents read at the ends of the horizontal absorber 24 , and C x and C y are calibration coefficients that convert current balance readings into coordinates. C x and C y are determined in reference calibration runs with known beam positions. The balance of the currents from the end of the vertical plate 22 determine the Y coordinate and the balance of the currents from the end of the horizontal plate 24 determine the X coordinate. The voltage readouts V are used to check the consistency of the measured currents or can be used to set an alarm signal or to lock the beam in the center position. The absorbers 22 , 24 are preferably formed of thermo-resistive material. An especially preferred thermo-resistive material of construction for the absorbers is chemical vapor deposition (CVD) silicon carbide (SiC). CVD SiC is a chemically inert, extremely radiation-hard, thermo-resistive semiconductor capable of withstanding working temperatures up to 2000 degrees Kelvin, with its electrical resistivity very sensitive to temperature. The good thermoconductivity of CVD SiC enables it to be used in high-current particle beams. The beam position detector 20 of FIG. 1 consists of two CVD SiC plates 22 , 24 positioned orthogonal to the beam direction or path 26 , one vertically 22 and one horizontally 24 . The width of the plates 22 , 24 would correspond to the designed area on the dump where the beam must be directed. The correctly positioned high-energy charged particle beam would cause a measurable temperature increase in both plates and a misdirected beam would be indicated by a missing signal in one or both of the plates. FIGS. 4-9 present the calibration data obtained on the prototype Beam Position Detector (BPD) device corresponding to the preferred embodiment shown in FIG. 1 , set up inside the electron beam line of an electron accelerator at the vicinity of the beam dump. The conventional Beam Position Monitors (BPMs) were installed approximately 30 meters upstream from the BPD and a few meters upstream of the relatively thick experimental target. The BPMs were thus used to measure the position of the beam prior to the thick helium target, where the quality is good and a conventional beam position monitor is adequate. The quality focused electron beam with energies from 1 to 5 GeV and beam currents in the range of 1 to 120 μA, with transverse dimensions of the order of 0.1 mm by 0.1 mm at the target, was dispersed to the transverse size of about 1 cm by 1 cm at the BPM position by scattering in the target. The calibrations were performed at a beam current of 30 μA. The symbols in the plots represent a series of measurements, one measurement every 10 seconds. The resultant BPM data is used to project the beam position to the place where the BPD is installed, assuming there is no non-linear beam deflection by magnetic fields around the beam line. The correlation of BPD and BPM readings is clearly seen. FIG. 4 depicts a plot of the x-coordinate of the conventional beam position monitor (X BPM ) projected to the location of the beam position detector versus time. FIG. 5 is a plot of the x-coordinate output of the beam position detector (X BPD ) of FIG. 1 versus time for the same time frame studied in FIG. 4 . A scatter plot was then made in FIG. 6 plotting X BPD versus X BPM . FIG. 7 is a plot of the y-coordinate output of the conventional beam position monitor (Y BPM ) projected to the location of the beam position detector versus time. FIG. 8 is a plot of the y-coordinate output of the beam position detector (Y BPD ) of FIG. 1 versus time for the same time frame studied in FIG. 7 . FIG. 9 is a scatter plot of Y BPD versus Y BPM . As previously stated, the BPM is used to measure the position of the beam prior to the target, at a point where the quality of the beam is good. X BPM and Y BPM are therefore extrapolated to the BPD position using BPM readings. X BPD is calculated using the balance of currents from the first absorber plate 22 of the BPD of FIG. 1 . Y BPD is calculated using the balance of currents from the second absorber plate 24 of the BPD of FIG. 1 . The plot of X BPD versus X BPM and the plot of Y BPD versus Y BPM show clear correlation. With reference to FIG. 11 , a first alternate embodiment of the beam position monitor 50 includes sets of thin parallel metallic conductors 52 deposited on the plates 22 , 24 to provide more detailed information on the beam size and profile. The electrical resistance of the sets of thin parallel metallic conductors would be much smaller than the resistance of the plate itself between the two conductors 52 . A voltage is applied between the first and the last conductor on a plate to create a voltage distribution across the plate, which is then measured at the ends of the conductors. Directing a high-energy particle beam on the plates 22 , 24 between two conductors will cause local heating of the plate thereby changing the resistance, and, correspondingly, the measured voltage between the conductors, thus locating the position of the beam across the plate. The pattern of changed voltage distribution measured at every conductor can be used to evaluate the beam profile across the plate. Using two orthogonal plates, one can measure the detailed beam distribution in horizontal and vertical directions. Referring to FIG. 10 there is depicted a second alternate embodiment of a particle beam position monitor 60 according to the present invention. The monitor 60 includes four resistive absorbers set across the beam path 26 . Two absorbers 62 , 64 are positioned orthogonal and vertically with respect to the beam path 26 and two absorbers 66 , 68 are positioned orthogonal and horizontally with respect to the beam path 26 . Each absorber provides information about a slice of the beam profile. The full beam profile can be obtained using the combined information from all of the absorbers. Another alternate embodiment of the beam position detector, not depicted herein, would include similar absorbers made of a transparent thermo-resistive glass material and be used to monitor the position of a powerful laser beam. A small fraction of the laser beam power dissipated in the glass absorber will cause local heating and thus a measurable resistance change. The preferred embodiment of the beam position monitor 20 shown in FIG. 1 features a simplified construction, using one vertical 22 and one horizontal 24 plate. The CVD SiC plates are preferably 50 mm width, 200 mm length, and 0.25 mm thick. Using the CVD SiC provides several advantages, including thermoconductivity comparable with copper and beryllium, high stiffness, machinability, stable up to 2000 degrees Kelvin, a resistance of between 200 and 600 kohm measured across the long ends of the rectangular plates, and high resistance response with resistivity falling 100 times in the temperature range of 50 to 500 degrees C. The CVD SiC plates are also resistant to degradation due to plasmas, acids, bases, and radiation. Experimentation with different experimental targets shows that the response from the BPD may depend on the target, and therefore each target must be calibrated separately. Different targets scatter the beam differently, producing different beam spot sizes and generating different numbers of secondary electrons, which go in the line along with the beam, with smaller energies. The magnetic fields along the beamline deviate these lower energy electrons more easily than the main beam, thus producing non-symmetric beam image at the BPD. Effectively, it may shift the BPD readout along the major direction of the deviation. Alternatively, the absorbers could be constructed of wires constructed of CVD SiC. The wires would be strung parallel to one another to form a rectangular shape, with the wires running longitudinally along the rectangular-shaped absorber. Each wire, if hit by a particle beam, would have its temperature elevated, thus allowing it to be detected by measuring its resistance. Having thus described the invention with reference to a preferred embodiment, it is to be understood that the invention is not so limited by the description herein but is defined as follows by the appended claims.	A beam position detector for measuring the properties of a charged particle beam, including the beam's position, size, shape, and intensity. One or more absorbers are constructed of thermo-resistive material and positioned to intercept and absorb a portion of the incoming beam power, thereby causing local heating of each absorber. The local temperature increase distribution across the absorber, or the distribution between different absorbers, will depend on the intensity, size, and position of the beam. The absorbers are constructed of a material having a strong dependence of electrical resistivity on temperature. The beam position detector has no moving parts in the vicinity of the beam and is especially suited to beam areas having high ionizing radiation dose rates or poor beam quality, including beams dispersed in the transverse direction and in their time radio frequency structure.	6
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 62/267,021 filed Dec. 14, 2015 entitled “Slow Illuminating And Customizable Light System”, the contents of which are expressly incorporated herein by reference. STATEMENT REGARDING FEDERALLY FUNDED RESEARCH [0002] None. BACKGROUND [0003] I. Field of the Invention [0004] The present invention relates generally to the fields of outdoor lighting and more particularly to a flexible, slow illuminating light. [0005] II. Description of Related Art [0006] Many external lighting systems may be activated by movement and frequently illuminate immediately upon activation. Moreover, the light is generally bright, white light so as to be readily visible to humans. This facilitates observation and also serves as a deterrent to intruders. SUMMARY [0007] The present disclosure is directed to an illumination system comprising a housing, at least one illumination arm affixed to said housing, wherein the illumination arms are flexible and wherein the distal end of each illumination arm comprises an illumination head, the illumination head comprising at least two bulbs of different colors and a driver system capable of controlling the rate of current to said bulbs. [0008] In addition, the illumination heads of the system further comprise a motion sensor within said head. [0009] It is contemplated that any embodiment of a method or composition described herein can be implemented with respect to any other method or composition described herein. [0010] The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” [0011] The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternative are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” [0012] Throughout this application, the term “about” is used to indicate that a value includes the standard deviation of error for the device or method being employed to determine the value. [0013] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. [0014] Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific 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. DESCRIPTION OF THE DRAWINGS [0015] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of the specification embodiments presented herein. [0016] FIG. 1 is an image showing features of the system outlined in the present disclosure. [0017] FIG. 2 is an image showing exemplary placement of multiple different colored bulbs in an illumination head. [0018] FIG. 3 is an image showing illumination heads capable of independent movement as outlined herein. DESCRIPTION [0019] While current methods of illumination are effective, there exists a need in the art for improved illumination systems that provide flexibility, light interchangeability and control over the rate of illumination. Accordingly, the present disclosure provides an illumination system in which multiple attributes are controlled by a user or factory setting. As described herein, these attributes include but are not limited to direction of illumination color of illumination and rate of illumination Such illumination systems find multiple uses, for instance, in security, wildlife surveillance and/or hunting. [0020] Turning to FIG. 1 , an illumination system 101 of the present disclosure provides a housing unit 102 comprising a lid 103 affixed to a base 104 . The lid 103 and base 104 may be affixed by any of a variety of known methods including at least one, two, three or more hinges or may be affixed with screws. The lid may be closably sealed to the base by one or more latches or 1, 2, 3, 4 or more screws 106 as is known in the art. The latch may comprise one or more locks, including a keyed lock, combination lock and the like. Batteries and other electrical controls including the microprocessor may be found within the housing. [0021] The housing may also be affixed to mounting pieces 107 . These provide for mounting the unit to a post, tree, house or other desired location. [0022] Also attached to the housing is at least one flexible light element 108 . The flexible light element is comprised of a flexible arm that can be bent in any desirable direction. To the distal end of the flexible arm is affixed a lighting head unit 109 . In some embodiments the lighting head unit is rotationally affixed to the flexible arm 110 by any of a variety of methods, such as a ball and socket joint, such as, but not limited to a Loc Line adapter In one embodiment the lighting head unit contains the electronic controls such as a microprocessor, capable of regulating the intensity and rate of illumination of the lights in the head unit. That is the microprocessor circuit allows the light to slowly brighten after the motion is detected. The microprocessor circuit also helps control the balance to the drivers since the different colored lights operate on different currents. In an alternative embodiment, the microprocessor may be in the battery box along with other electronics. There can be 2 drivers, (one for each color) in each head, along with 12 LEDs (6 of each color). The light uses a battery, which may be a 12-volt battery that is optionally charged by a solar panel. [0023] In some embodiments the system includes an on/off switch, a solar panel jack and connectors, such as but not limited to Amphenol connectors. Preferably the system includes an electronics master board comprising a microprocessor configured to control the rate of illumination, balance of the LEDs and the time the light stays active after motion ceases and a battery. The system also includes at least one illumination arm affixed to said housing, wherein said illumination arm is flexible and wherein the distal end of each illumination arm comprises an illumination head. The illumination head comprises at least two bulbs of different color and a driver system, such as but not limited to a pulse width modulation (PWM) driver system, capable of controlling the current to said bulbs. The driver system is configured to regulate the length of time the light is illuminated. The drivers used for each color are, for instance, PWM drivers and the microprocessor controls how long each cycle is. This allows for a situation in which the LED illuminates at maximum brightness or less than maximum brightness to use less power. The PWM allows for control where the “on time” is at the brightest without wasting energy. [0024] In one embodiment the lighting head unit also comprises at least two discrete bulbs 111 . [0025] In general it is preferable for each lighting head to contain at least 3, 4, 5, 6, 7, 8, 9 or more, such as up to 10, up to 20, up to 30, up to 40 bulbs. In some embodiments these bulbs are of a single color, while in some embodiment the bulbs are of at least a first and second different color, such as red and green bulbs. For instance in one non-limiting embodiment 6 red and 6 green bulbs are used. See FIG. 2 . Any number of any color bulbs may find use in the system. Notably, in some embodiment the bulbs are replaceable and can be interchanged with different colored bulbs as desired. [0026] Benefits of using lights of different colors include the use of bright, white bulbs in security lights, and the use of red/green lights for hunting as certain game are unable to detect or only modestly detect the non-white light. In particular it is noted that feral hogs, which represent a significant and growing problem for farmers, ranchers and the like, do not see the color orange or do not see it well. As such, rather than illuminate with white light and startle the game, illumination is accomplished with red/green lights such that the game is not startled. In addition, other bulbs, such as UV or bulbs emitting different wavelengths find use in the illumination system described herein. In some embodiments using bulbs of different colors and wattage specific colors of illumination can be achieved. For instance using a 1 watt red bulb and a 0.5 watt green bulb results in an orange light, a color not detectable by certain game species, such as feral hogs, in some embodiments, the lights, which may be LED lights, are powered by Pulse Width Modulated LED drivers to conserve the battery power. Red lights are outside of many animals' detectable visible wavelength. They also are not necessarily bright enough for the human eye to perceptibly see. Green lights are much more perceptibly bright to the human eye, but green is barely in the visible spectrum of the animals. By using this red/green color combination, and by properly balancing the perceptible brightness of the 2 colors, (i.e. dimming the green and brightening the red), a bright orange light can be achieved and still stay outside of the visible wavelength of some animal such as hogs. [0027] Also included in the lighting head is a motion sensor 112 . Motion sensors are known in the art. However, in the illumination system described herein the motion sensor is found in the flexible lighting unit. This allows for customizable, independently designed monitoring for motion based on a single fixed location of the illumination housing. That is, generally motion sensors are affixed to the housing unit and therefore are capable of monitoring only activity in the direction the housing unit is facing. While these detectors are capable of detecting movement within a particular field of detection of about 160 degrees in one direction, the present illumination system has customizable and independently configurable motion sensors. That is, each illumination arm can be independently moved to a particular direction and optionally independently illuminated. In some embodiments upon activation of a motion detector all heads may illuminate. Alternatively, in some embodiments, the heads are independently regulated by the respective motion detector. See FIG. 3 . Thus, when two lights are pointed 180 degrees apart, each may have a range of detection of potentially 160 degrees each. Using two independent illumination arms, therefore doubles the range of detection. Likewise, adding a third, fourth light or more, increases the range of detection such that a 360-degree coverage is possible. That is, the infinitely adjustable heads allow the user to point the light or lights where it/they will be most effective. [0028] In some embodiments the motion sensors are activated when a certain level of darkness is reached and inactivated when a certain level of light is reached. In some embodiments, when motion is detected, a microprocessor is activated and the microprocessor circuit slowly increases the current to the lights, e.g. LED drivers. These in turn power the lights which increasingly get brighter. The lights remain at this brightness until motion ceases. When the motion is no longer detected the light turns off after a certain factory set time. [0029] The rate of illumination also may be independently controlled for each illumination head or in some embodiments it may be the same for each. In some embodiments maximum illumination occurs instantly upon activation of the motion sensor. However, in alternative embodiments illumination may take 2, 5, 10, 20, 30, 60, 90, 120, 150, 180, 210, 240, 270 or more seconds to reach maximum illumination. In this embodiment the illumination occurs over a period of from 1-4 minutes, more preferably from about 2-3 minutes. [0030] In addition, illumination intensity may be customized within each illumination head. That is, in some instances, maximum illumination is desired. However, in some embodiments, less than maximum illumination is desired, such as 90%, 75%, 50%, 30%, or 10% of maximum illumination is needed or desired. [0031] Illumination controls may be found in the housing unit, or in some embodiments may be found in each of the respective illumination heads. These controllers independently configurable with respect to rate of illumination, duration of illumination, sensitivity of the motion sensor. [0032] The proximal end of the illumination arm is reversibly and flexibly attached to the housing. This allows for interchangeability of each independent arm. In some embodiments the connections is via a LocLine connection. In one embodiment the connections between the head and neck assembly and the housing unit is modular. That is, connections such as but not limited to locking plug, military connection or other type that allows the connections to make or facilitate electrical connections with the battery and programming wires, allowing the assemblies to be removed and/or replaced. Amphenol Connector As described herein, in one embodiment the electronics, including PCT, drivers, motion detector and bulbs (LEDs) are housed within each head. Thus, should one arm or illumination head need to be replaced this can be done without replacing the entire unit. This also provides for a system to which illumination heads/arms can be added or removed according to the desire and need of the user. As such, the housing units are configured to receive at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 independent illumination arms. [0033] Another optional feature of the illumination system is a reversible attachable solar panel. [0034] The panel may be configured to charge the batteries found in housing as is known in the art. Other features of the system include an on/off switch and a solar panel jack. In some embodiments the system is UV resistant and may be optionally colored in camouflage print. In some embodiments the system is waterproof or water resistant. [0035] Once made, the illumination system described herein is applicable to multiple uses. In one embodiment the illumination system finds use as a precisely configurable security system. In this embodiment, the mounted system can be configured to detect motion in multiple desired locations and the illumination independently controlled. In an alternative embodiment the illumination system finds use as a customizable hunting light. In this embodiment, the mounted or affixed system can be configured to detect movement in multiple, distinct or overlapping regions, the lighting color, rate of illumination and intensity can all be independently configured or are optionally factory set [0036] While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the present invention.	The present invention relates generally to the fields of outdoor lighting and more particularly to a flexible, slow illuminating light.	5
This application is a continuation of copending application Ser. No. 10/865,214 in the name of Walter Monroe Hutchins filed Jun. 10, 2004, the contents of which are hereby incorporated by reference as if fully set forth herein. TECHNICAL FIELD The present invention relates generally to fluid retaining mop structures, and more particularly to a mop head incorporating fluid retaining strand elements of contoured, tubular construction incorporating an arrangement of elongate surface channel depressions extending at least partially along the length of such strand elements interposed between raised profile protrusions. A process for forming the mop head is also provided. BACKGROUND OF THE INVENTION Mop heads incorporating tubular strand elements of so-called “edgeless” construction are known. One such construction, which is marketed by Contec Inc. of Spartanburg, S.C., is formed from a skein of circular knit material of tubular construction which is formed on a winding apparatus using a pair of support bars which rotate relative to one another. The skein structure is formed from a single continuous tube of the knit material. Upon removal from the winding apparatus, the skein thus has an interior and two ends formed by the reverse folds in the knit tube where it has been passed around the winder bars. The skein structure is thereafter inserted into a relatively narrow width containment sleeve which is seamed to the interior of the skein structure at a substantially central location to contain the tubular elements in the wound structure. Seams are also applied at slightly inboard positions relative to the folded over ends of the skein structure so as to avoid undue spreading of the individual folded over elements. The mop head so formed is thereafter attached to a handle at the central containment sleeve. Importantly, the prior mop heads formed in this manner have utilized a circular knit, tubular structure in the material forming the skein having a substantially uniform flat exterior surface. SUMMARY OF THE INVENTION The present invention provides advantages and alternatives over the prior art by utilizing a relatively narrow diameter, knit tubular material to form the strands of a mop head substantially in the same manner as described above but wherein the tubular material incorporates an arrangement of elongate depressed channels and raised profile segments or ridges extending along its surface in the length direction rather than using the flat surface structure of the prior constructions. This construction has surprisingly been found to increase the overall fluid retaining or sorbency capacity of the mop relative to the prior flat surface construction even while lowering the overall mass of the mop head. That is, more fluid may be retained even though less fluid retaining material is utilized thus providing a substantial improvement over the prior known construction. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings which are incorporated in and which constitute a part of this specification illustrate potentially preferred embodiments and practices in accordance with the present invention and, together the general description of the invention given above and the detailed description set form below, serve to explain the principles of the invention wherein: FIG. 1 is a simplified illustration of a circular knitting machine as will be well known to those of skill in the art for use in forming the absorptive string elements of a mop head according to the present invention; FIG. 2 illustrates a mop head according to the present invention in attached relation to a handle structure; FIG. 3 is an elevation plan view of the mop head in FIG. 2 ; FIG. 4 is a cross-sectional side view of the mop head in FIG. 3 . FIG. 5 illustrates an exemplary cross-section of an individual strand taken through line 5 - 5 in FIG. 1 . While the invention has been illustrated and generally described above and will hereinafter be described in connection with certain potentially preferred embodiments and procedures, it is to be understood that in no event is the invention to be limited to such illustrated and described embodiments and procedures. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the broad principles of this invention within the true spirit and scope thereof. DESCRIPTION OF THE PREFERRED EMBODIMENT Reference will now be made to the various drawings wherein to the extent possible, like reference numerals are utilized to designate like components throughout the various views. In FIG. 1 , there is illustrated a circular knitting machine 10 such as will be well known to those of skill in the art. By way of example only, and not limitation, one knitting machine 10 which has been identified as suitable for practice of the present invention is a model ST3AH/ZA high speed, single feed, circular knit machine having a cylinder size of 1.5 inches in diameter and 48 needle slots available manufactured by Lamb Knitting Machine Corporation having a place of business in Chicopee, Mass. USA. According to one contemplated practice, in operation a pair of yarns 12 , 12 A is delivered from spools 13 , 13 A to the knitting machine 10 for formation of a tubular knit structure 14 . The yarn 12 is preferably a 150 denier singles textured polyester having either an “S” or “Z” twist construction. The yarn 12 A is preferably a 150 denier two ply textured polyester wherein one ply has an “S” twist and the other ply has a “Z” twist. Thus, the two yarn system incorporates yarn orientations with a combination of opposing twists. This balance in twist permits the knit structure to avoid undue curling when subjected to laundering operations. Of course, the particular yarn system selected may be varied as desired by the user. The tubular knit structure 14 which is formed according to the potentially preferred practice of the invention includes an arrangement of elongate channel depressions 20 running along the length of the tubular knit structure 14 ( FIG. 5 ). The depressions 20 are disposed between raised profile surface protrusions 24 across the surface of the tubular knit structure 14 such that an undulating or corrugated surface profile is provided wherein the elongate channels and surface protrusions extend in alternating substantially parallel relation. According to a potentially preferred practice, the illustrated arrangement of channel depressions 20 and raised profile protrusions 24 is achieved by using a modified needle arrangement in the knitting equipment to create a space between courses formed during the knitting process. According to one exemplary practice, the circular knit machine as described above is modified to incorporate a needle arrangement with four needles in and two needles out in an arrangement which is repeated eight times around the circumference of the cylinder. This produces a profiled surface with eight cooperating channel depressions 20 and eight raised profile protrusions 24 . Of course this number may be greater or lower as desired but will preferably be at least four and will more preferably be about 6 or greater. According to one potentially preferred practice the machinery is set up to produce a tubular knit structure with fourteen courses per inch (relaxed state) and a weight of about 6.1 grams per linear yard (relaxed state). The resulting construction is a modified jersey knit utilizing thirty-two active needles for knitting. It is contemplated that the tubular knit structure as described will form the fluid retaining strands of a mop head 30 attached to a handle 40 to form a mop 50 as illustrated in FIG. 2 . As best illustrated through simultaneous reference to FIGS. 2-4 , the mop head 30 is formed from a skein of the tubular knit material 14 . As previously indicated, such a structure may be formed by winding an extended length of the tubular knit material multiple times around a pair of spaced-apart bars and then removing the formed structure from those spaced-apart bars. As illustrated, the resultant skein structure has an arrangement of folds 32 at either end of the skein structure. As will be appreciated, the folds 32 are formed at the location where the tubular knit material is wrapped around the opposing bars during the winding operation. Of course, it is also contemplated that a similar structure may be formed by hand coiling or other techniques as may be desired. Moreover, while it may be desirable to use a single long piece of tubular knit material 14 folded upon itself multiple times to form the mop head, it is also contemplated that two or more shorter lengths may be used if desired. Thus, it is to be understood that by the term “skein” is meant any structure in which one or more lengths of elongate material are folded upon themselves such that the folds define an edge boundary with discrete strand elements extending away from the edge boundary. According to the illustrated and potentially preferred practice, the skein structure forming the mop head 30 is fitted into a containment sleeve element 34 of fabric or the like which is then seamed in place so as to hold the strands of tubular knit material 14 in adjacent relation to one another at a central location. Moreover, the ends of the tubular knit material where the winding begins and concludes are also held in hidden relation beneath the containment sleeve element 34 . Finally, strips of material 36 are seamed in transverse relation to the strands of tubular knit material 14 at positions inboard of the folds 32 so as to maintain a desired adjacent relation of the strand elements at each end of the mop head 30 . The mop head 30 may thereafter be washed and dried prior to attachment to the handle 40 . As previously indicated, the adjustment of the circular knitting machine 10 to produce the tubular knit material 14 with interspersed elongate channel depressions 20 and raised profile protrusions 24 yields substantially improved moisture retention capacity even when lower weights of material are utilized. This moisture retention capacity is referred to as “sorbent capacity” and may be made up of moisture retention resulting from absorption and/or adsorption at the strands of tubular knit material. In this regard, it is contemplated that the benefits of the present invention will be applicable to both hydrophilic as well as hydrophobic materials of construction although polyester which is hydrophobic may be particularly preferred. In order to evaluate the relative performance of a mop head formed according to the present invention, exemplary mop heads formed with fluid retaining strands having elongate channel depressions and raised profile protrusions were weighed in a dry state and were thereafter immersed in water until fully saturated and then weighed in a wet state once dripping had substantially ceased. The contoured surface mop heads were formed according to the potentially preferred practice as described above on a 1.5 inch diameter circular knitting head with an arrangement of four needles in and two needles out repeated eight times around the circumference. Mop heads of similar construction but incorporating flat surface tubular strands of knit material formed on the same knitting head but with all needles in were tested according to the same procedure. Each of the structures was also tested to measure sorbency in a wet state wherein the wet mop was immersed after wringing excess moisture from the mop head following initial saturation. The results are set forth in Table I below: TABLE 1 Dry mop sorbent Wet mop sorbent Dry mop weight capacity capacity Wet mop weight In In Intrinsic Extrinsic Intrinsic Extrinsic % In In grams ounces (mL/g) mL/mop (mL/g) (mL/mop) wringability grams ounces Flat 1 433 15.3 2.83 1225 0.92 400 32.7% 1258 44.4 Flat 2 431 15.2 2.67 1150 0.93 400 34.8% 1181 41.7 Averages 432 15.2 2.75 1188 0.93 400 33.7% 1220 43.0 Contoured 1 399 14.1 4.39 1750 2.01 800 45.7% 1349 47.6 Contoured 2 399 14.1 4.26 1700 2.13 850 50.0% 1249 44.1 Contoured 3 402 14.2 4.35 1750 1.99 800 45.7% 1352 47.7 Contoured 4 399 14.1 4.26 1700 1.88 750 44.1% 1349 47.6 Contoured 5 400 14.1 4.25 1700 2.13 850 50.0% 1250 44.1 Contoured 6 401 14.1 4.49 1800 2.12 850 47.2% 1351 47.7 Contoured 7 399 14.1 4.39 1750 2.13 850 48.6% 1299 45.8 Averages 400 14.1 4.34 1736 2.05 821 47.3% 1314 46.4 Flat 1 and 2 are the prior structures and contoured 1-6 are specimens of the present invention. As can be seen, the mop structure of the present invention exhibited substantially greater intrinsic sorbent capacity in both the wet and dry states relative the prior structure using flat tube fluid containment strands. While the present invention has been illustrated and described in relation to certain exemplary and potentially preferred embodiments and practices, it is to be understood that such embodiments and practices are illustrative only and that the present invention in no event to be limited thereto. Rather, it is contemplated the modifications and variations will no doubt occur to those of skill in the art upon reading the above description and/or through practice of the invention. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations which may incorporate the broad concepts of the present invention within the full spirit and scope thereof.	An edgeless mop utilizing a relatively narrow diameter, knit tubular material to form the strands of a mop head wherein the tubular material incorporates an arrangement of elongate depressed channels and raised profile segments extending along its surface in the length direction. This construction increases the overall fluid retaining or sorbency capacity of the mop even while lowering the overall mass of the mop head.	3
BACKGROUND OF THE INVENTION The present invention relates generally to a method for separation of an ester such as methyl iso-butyrate or methyl methacrylate from a reaction mixture in which the ester is formed by reaction of an organic acid with an alcohol. In the known industrial method, an ester is generally produced by reacting alcohol with an equimolar amount of organic acid in the presence of a suitable catalyst. The thus produced ester is then purified by fractional distillation. This reaction however suffers from the disadvantage that it is never complete and must be closely controlled in order to avoid formation of by-products. Although the reaction theoretically should be complete, even under ideal conditions, the reaction mixture usually contains a substantial proportion of unreacted alcohol and organic acid which must be separated from the ester. The separation of the ester from the reactants by simple fractional distillation is rendered difficult owing to the formation of alcohol-ester or ester-water azeotropes. As a result of studies on the separation of esters from the reaction mixture, it has now been found that the ester may be readily separated by reacting an alcohol with an excess amount of organic acid based on that of alcohol, and removing the unreacted alcohol from the reaction mixture as an alcohol-ester azeotrope. SUMMARY OF THE INVENTION Broadly the present invention is directed to the separation of an ester particularly methyl iso-butyrate and methyl methacrylate from a reaction mixture comprising ester, alcohol, organic acid and water. More specifically, this invention is directed to a method for the separation of ester from a reaction mixture comprising ester, alcohol, organic acid and water which comprises reacting an alcohol with an excess amount of organic acid based on that of alcohol, removing the unreacted alcohol in the reaction mixture as an alcohol-ester azeotrope and recovering the ester from the mixture which is comprised of ester, organic acid and water and which is substantially free of alcohol. The present invention is based on the following principle. There are four components, i.e. ester, alcohol, organic acid and water in the reaction mixture obtained by reaction of alcohol with organic acid. When the reaction mixture is subjected to distillation, an alcohol-ester azeotrope and an ester-water azeotrope may be formed. Among the four components and two azeotropes for the two esters described above, the alcohol-ester azeotrope has the lowest boiling point, the next is the ester-water azeotrope, the third is the ester, and the fourth is the organic acid. Therefore, when the reaction mixture is subjected to distillation, firstly, alcohol-ester azeotrope is formed and is distilled away. After all of the alcohol is distilled away, an ester-water azeotrope is formed. The ester is readily separated from a mixture which is comprised of ester, water and organic acid and which is substantially free of alcohol. In order to obtain an ester in a high yield according to the above-described method, the amount of the alcohol contained in the reaction mixture must be minimized; and therefore, in the reaction of alcohol with organic acid, an excess amount of organic acid must be used to that of alcohol. DETAILED DESCRIPTION OF THE INVENTION The accompanying drawing is a process flow diagram illustrating a preferred continuous method for carrying out the invention. With reference to the drawing, alcohol and organic acid are fed, by means of connection 1, to reactor 3 packed with a cation exchange resin 2 where an ester is formed by reaction of the organic acid with the alcohol. A reaction mixture from the reactor which consists of ester, alcohol, organic acid and water is fed, by means of connection 4, to a first distillation column 5 where an overhead fraction of alcohol-ester azeotrope is formed and is returned, by means of connection 6, to reactor 3. The base fraction from distillation column 5 which is a mixture of ester, organic acid and water and which is substantially free of alcohol is fed, by means of connection 7, to a second distillation column 8 where an overhead fraction of ester-water azeotrope is formed and is passed, by means of connection 9, to separator 10. The ester layer, separated in separator 10, is refluxed, by means of connection 11, to column 8. The water layer is discharged by means of connection 12. The desired ester is recovered, as a side cut, by means of connection 13 from the second distillation column 8. The base fraction from column 8, which consists of organic acid is returned to reactor 3 by means of connection 14. According to the present invention, the reaction of organic acid with alcohol is carried out in an excess amount of organic acid to that of alcohol in the presence of a suitable catalyst. The more organic acid there is, the smaller the amount of unreacted alcohol. However, if the amount of organic acid is too excessive, the process becomes uneconomical because of the increase of circulation of organic acid. Therefore, the amount of organic acid is usually 1.5-10 moles, preferably 2-4 moles per 1 mole of alcohol. In accordance with the invention, the amount of unreacted alcohol in the reaction mixture should be less than 4.0% (W/W) preferably less than 2.0% (W/W). As the catalyst for esterification, any catalyst may be used so long as it catalyzes the reaction of organic acid with alcohol. Examples of suitable catalysts are mineral acids such as sulfuric acid, phosphoric acid, etc., organic acids such as benzene sulfonic acid, p-toluene sulfonic acid, etc. and cation exchange resin, etc. The reaction is carried out by the known reaction systems according to the type of catalyst. When a homogeneous catalyst such as a solution is utilized, any reactor may be used. When a solid type catalyst is utilized, the reaction is preferably carried out in a fluidized bed or fixed bed. When the reaction temperature is low, the rate of reaction is slow and it takes much time to reach the equiliblium. On the other hand, when it is high, by-products are produced. Therefore, the reaction is carried out at a temperature of 30°-120° C. preferably at 50°-90° C. When raw materials or products are liable to be polymerized in the reaction or distillation steps, a polymerization inhibitor such as hydroquinone, hydroquinone mono-methyl ether, or the like may be added to the reactor or the distillation column. After the completion of the reaction, the reaction mixture is neutralized with an alkaline solution such as sodium hydroxide, etc. and is subjected to filtration for removing the catalyst. When a cation exchange resin is utilized as the catalyst, neutralization is unnecessary. Similarly, when the reaction is carried out in a fixed bed system, filtration is unnecessary. The filtrate is then introduced to the first distillation column which is controlled at atmospheric or reduced pressure and is subjected to distillation to form an alcohol-ester azeotrope. The temperature of the column is automatically determined by the column pressure and the components of the solution in the column. The azeotropic mixture is distilled away and is recycled to the reactor, if desired. In this case, the amount of ester utilized for making the azeotropic mixture with unreacted alcohol in the first distillation column is small because of the small amount of unreacted alcohol. The desired ester is recovered from the base fraction of the column which is a mixture of ester, water and organic acid according to known methods. For example, the base fraction is fed to the second distillation column where an ester-water azeotrope is formed in the column as an overhead fraction. The azeotropic mixture is removed to a separator where an ester layer and a water layer are formed. The ester layer is refluxed to the top of the second distillation column. The desired ester is then recovered and isolated as a side cut flow of the overhead fraction in the second distillation column, in high purity. The base fraction consisting of organic acid is usually recycled to the reactor. Any part or all of the separation and purification system above described can be operated at atmospheric pressure or under a vacuum. The second distillation column can be operated at any convenient reflux ratio and the refux ratio will vary depending on the components of the mixture introduced therein for separation. The proper reflux ratio for various mixtures can be readily determined by those skilled in the art. Usually, a reflux ratio varying from about 2:1 to 10:1 can be employed satisfactory. Certain specific embodiments of the present invention are illustrated by the following representative examples. EXAMPLE 1 In this example, methyl iso-butyrate is synthesized from iso-butyric acid and methanol in a reactor packed with 100 ml of a cation exchange resin, namely PK 220 (trade mark of Mitsubishi Chemical Industries, Ltd.), as the catalyst. Iso-butyric acid, at a rate of 245.8 g/h, methanol at a rate of 40.1 g/h, and a mixture of 70% methanol, 29% methyl iso-butyrate and 1% water at a rate of 6.6 g/h are fed to the reactor. The molar ratio of iso-butyric acid to methanol at the inlet of the reactor is maintained at 2.0. The reaction is carried out at a temperature of 90° C. and at a pressure of 4Kg/cm 2 Gage of nitrogen gas for suppressing vaporization of the reaction product. Under these conditions, the reaction proceeds quantitatively i.e., most of the alcohol is converted to ester, and the yield of methyl iso-butyrate is 89.7% based on methanol supplied. The reaction mixture containing 1.6% methanol, 44.4% methyl iso-butyrate, 7.7% water and 46.3% iso-butyric acid is separated in the manner described above with reference to the drawing. More specifically, the reaction mixture is introduced to a first distillation column which is maintained at atmospheric pressure. An overhead fraction containing 70% methanol, 29% methyl iso-butyrate and 1% water and having a boiling point of 64° C. is recycled to the reactor at a rate of 6.6 g/h. The base fraction of the column, having a temperature of 100° C., is fed to a second distillation column having a side cut outlet, which is maintained at atmospheric pressure. An azeotropic mixture of methyl iso-butyrate and water having a boiling point of 78° C., produced as an overhead fraction in the second column is removed to a separator. The ester layer formed in the separator is refluxed back to the second distillation column; and the water layer, containing 1.4% methyl iso-butyrate, is discharged out of the system at a rate of 22.7 g/h. The fraction of methyl iso-butyrate having a temperature of 92° C. is taken from the side cut outlet at a rate of 127.8 g/h. The purity of the methyl iso-butyrate is 99.8% and the rest is water. Iso-butyric acid having a temperature of 158° C. is taken from the base of the column at a rate of 135.5 g/h and recycled to the reactor. EXAMPLE 2 In this example, methyl methacrylate is synthesized from methanol and methacrylic acid in a manner similar to that described in Example 1. A mixture containing 11% methanol, 0.2% methyl methacrylate, 0.02% water and 88.8% methacrylic acid is fed to the reactor at a rate of 300 g/h. Hydroquinone as a polymerization inhibitor is also fed to the reactor at a ratio of 100 ppm based on the total raw materials. The reaction is carried out at a temperature of 77° C. and at a pressure of 2 Kg/cm 2 Gage with nitrogen gas. The reaction proceeds quantitatively and the yield of methyl methacrylate is 92.9% based on the amount of supplied methanol. The reaction mixture containing 0.8% methanol, 32.2% methyl methacrylate, 5.8% water and 61.2% methacrylic acid is introduced to a first distillation column which is maintained at a pressure of 400 mmHg. An overhead fraction containing 78.0% methanol, 21.0% methyl methacrylate and 1.0% water and having a boiling point of 48° C. is recycled to the reactor at a rate of 3.0 g/h. The base fraction, having a temperature of 100° C., is taken from the base of the column and removed to a second distillation column which is maintained at a pressure of 200 mmHg. An overhead fraction, having a boiling point of 49° C. and consisting of methyl methacrylate and water is removed to a separator to form an ester layer and a water layer. The ester layer is refluxed to the top of the second distillation column and the water layer, containing 1.5% methyl methacrylate, is discharged out of the system at a rate of 17.4 g/h. The fraction of methyl methacrylate having a temperature of 62° C. is taken from the side cut outlet at a rate of 95.9 g/h. The purity of the methyl methacrylate is 99.8% and the rest is water. The base fraction is taken from the base of the column at a rate of 183.7 g/h and recycled to the reactor.	An improved method for separating an ester formed in a reaction mixture is disclosed. The method comprises controlling the ratio of organic acid and alcohol utilized and the removal of unreacted alcohol as an alcohol-ester azeotrope.	2
TECHNICAL FIELD This invention relates to new and useful improvements in a method for counteracting the deleterious effects of sodium chloride on the human body. More particularly, the invention relates to the administration of specific compositions or mixtures of compounds which are antagonists for sodium chloride. BACKGROUND ART It has become apparent in recent years that the ingestion of sodium chloride, especially at the higher levels to which humans have become accustomed, has deleterious effects, mainly related to the cardiovascular system, e.g., high blood pressure and arteriosclerosis. Such ingestion has also been shown to also encourage the growth of tumors. Efforts to restrict the ingestion of salt by eating low or unsalted food or substitute alternate condiments for salt has not been very successful. Therefore, it is preferred to develop non-toxic compounds which counteract the effects of salt and which can be ingested separately or along with the salt. U.S. Pat. No. 4,499,078 suggests one method for achieving this result. The patent discloses that the anabolic effects of salt on a human body can be reduced by ingesting a compound which has an catabolic action. Specifically, the patent discloses that a magnesium compound containing bivalent negative sulfur may be taken with the salt or separately to offset the effects of the salt on the body. The content of that patent is expressly incorporated by reference herein. The present invention relates to an improvement in such compounds for more effective counteraction of the deleterious effects of sodium chloride on the body, particularly with regard to the effect of sodium chloride on neoplastic diseases. SUMMARY OF THE INVENTION The invention relates to a composition comprising the combination of at least one compound containing a cation of magnesium, calcium, or strontium and an anion of bivalent negative sulfur or selenium, and at least one compound containing a cation of lithium or potassium and an anion of bivalent negative sulfur or selenium. A preferred bivalent negative sulfur is a thiosulfate or thiocyanate anion, and these compositions may also contain a compound containing a fluoride, silicon or oxygen anion. Advantageously, the magnesium, calcium or strontium compounds are present in an amount of about 2:1 to 20:1 of the lithium or potassium compounds. The invention also relates to a composition comprising the combination of at least one of magnesium, calcium or strontium thiosulfate, at least one of magnesium, calcium, or strontium thiocyanate, and at least one of lithium or potassium thiosulfate. In this composition, the relative amounts of magnesium, calcium and strontium thiosulfate to magnesium calcium, and strontium thiocyanate to lithium or potassium thiosulfate ranges from about 2:1:1 to about 20:3:1. The composition can also include lithium or potassium fluoride. An other embodiment of the invention includes compositions of sodium chloride along with the compounds described hereinabove. In these mixtures, the sodium chloride is present in an amount of about 66 to 90 weight percent and preferably between about 75 and 85 weight percent of the composition. The invention also contemplates a method for counteracting the adverse effects of sodium chloride on the human body which comprises administering to the body one of the compositions described above. These compositions may or may not contain salt. In this method, the amount of composition to be administered ranges from between 0.5 and 10% by weight, and preferably about 2%, in a water solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In U.S. Pat. No. 4,499,078, it was established that the biological activity of various compounds with the body can be classified as either anabolic (constructive) or catabolic (destructive). It was also shown that sodium chloride has an anabolic effect, whereas compounds containing bivalent negative sulfur have a catabolic effect. Thus, the anabolic effect of the sulfur counteracts the anabolic effect of the sodium chloride. The manifest action of sodium chloride upon the appearance and growth of cancers has been established through several experiments. Tumors were produced by a transplant into the hind leg of rats and mice. These tumors were found to grow larger and more rapidly when the animals also received sodium chloride in their drinking water. The size and growth of the resultant tumors caused the animals to die earlier than those who did not ingest the salt. In groups of 100 exbreeder mice of the strain FC 1 , the number of spontaneous mammary tumors and the death from other conditions was recorded, during a one year observation. Spontaneous cancer was shown to be increased by the salt intake. In untreated animals, considered as controls, the average for 100 animals in one year observation was around 44% of spontaneous mammary cancers and of 15% death from other conditions than cancer. The addition of 2% salt in drinking water increased the spontaneous cancer to 65% for one year and a mortality of 20% from other conditions. In animals injected intramuscularly with the carcinogens methylcholanthrene or benzyprene, the number of positive results was not only markedly increased but the tumors appeared earlier when the animals also ingested salt. All these experiments are indicative of a marked enhancement upon the appearance, growth and malignant evolution of cancer by the action of ingested sodium chloride Statistical studies have also shown a relationship between the high intake of salt and arteriosclerosis. U.S. Pat. No. 4,499,078 showed that, in New Zealand rabbits, the intake of 2 g of cholesterol daily induced the appearance of aortic atheromatosis, and that the addition of salt in the drinking water increases the appearance of such atheromas. The fact is that the diet of people in civilized countries includes an amount of salt which is about ten times higher than the amount considered to be necessary physiologically. Thus, applicant believes that the high occurrence of arteriosclerosis and even cancer may be at least partially attributed to this high sodium chloride intake. A study of the biological action of the elements has shown the existence of antagonistic actions according to their reciprocal characters and position in the periodic table. Besides the antagonism between the anabolic and catabolic elements which is related to the different series to which they belong, other antagonistic actions occur between elements in following positions in the same series. In the specific case of sodium, the first antagonism is seen for the catabolic elements, while the second for potassium and lithium, as immediately inferior and superior elements in the same A-1 series. Thus, in such a case a biological antagonistic action is found to correspond to the following cations: magnesium, calcium, strontium, potassium and lithium. Chlorine antagonists include the bivalent negative sulfur, bivalent negative selenium, silicon, fluorine and oxygen. Especially active antagonists of the sodium chloride are the thiosulfates, thiocyanates, fluorides and chlorates of magnesium, calcium, strontium, potassium and lithium. To these, sodium or potassium chlorate may also be added due to their available oxygen. Research has shown that each of these preparations has a salutary effect upon the noxious manifestations of the sodium chloride in cancer and arteriosclerosis. While each one of these products has shown favorable effects by itself in the different experiments for counteracting the noxious effect of the administration of salt in cancer and arteriosclerosis, the concommitant use of two or more of these agents have shown improved results through what is believe to be synergistic action. The antisodium agents are used as such or added to the salt preparations, and used together. Taste, smell and water solubility are the main criteria for choosing from the different compounds, those which are not changing the qualities of the salt when added to it. It has been found that at least two of these agents in combination are very effective for counteracting the effects of salt. While any combination of bivalent negative sulfur containing compounds can be used, the most advantageous compounds to date are those containing a combination of nontoxic thiosulfates and thiocyanates. Preferably, at least one Group II thiosulfate or thiocyanate should be combined with at least one Group I thiosulfate or thiocyanate. Specifically, the combination of magnesium or calcium thiosulfate or thiocyanate with either strontium, potassium or lithium thiosulfate or thiocyanate has been found to be suitable for preparing formulations of this additive. Also combinations of these components can be varied or mixed to provide additional formulations which would be suitable. The following formulas were seen to give particularly good results: ______________________________________ Proportion (percent)Component Agent A Agent B______________________________________Magnesium thiosulfate 6 10Magnesium thiocyanate 3 3Calcium thiosulfate 3 3Strontium thiosulfate 1 1Potassium thiosulfate 2 2Lithium fluoride 0.03 0.05Sodium chloride balance balance______________________________________ In experiments using rats with Furth tumors transplanted in the hind leg, the administration of 2% salt in drinking water has increased the tumors (with an average, for 10 rats), to 30% more than in the untreated control rats. The use of a 2% mixture of the salt plus the antisodium chloride agents--has induced a manifest reduction of the tumor even with 10% below the controls without salt and of more than 35% for those having received sodium chloride alone. This action was markedly more manifest with the administration of the complex than with any compound alone, when added to the salt. From these experiments it has appeared advisable to use the modified salt to replace ordinary salt. Mice and rats which received either of the specific complex salts listed above in drinking water for over 6 months did not exhibit any side effects. When these solutions were given to young animals, their growth was not observed to be different from that of the control group (i.e.--those which received no solution). Based upon these experiments in animals, the continuous use of the corrected salt may have a basic influence upon both cancer and arteriosclerosis in humans as well. While it is apparent that the invention herein disclosed is well calculated to fulfill the objects above stated, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art, and it is intended that the appended claims over all such modifications and embodiments as fall within the true spirit and scope of the presnt invention.	A composition comprising at least one compound containing a cation of magnesium, calcium, or strontium and an anion of bivalent negative sulfur or selenium, and at least one compound containing a cation of lithium or potassium and an anion of bivalent negative sulfur or selenium. Also, a composition comprising salt and the previously described compounds along with a method for counteracting the adverse effects of sodium chloride on a human body by administering to the body between about 0.5 and 10% of one of the disclosed compositions, preferably in a water solution.	0
CROSS-REFERENCES TO RELATED APPLICATIONS This Application is a continuation application of U.S. application Ser. No. 12/823,509 filed on Jun. 25, 2010, which is a non-provisional of U.S. Application No. 61/220,306 filed Jun. 25, 2009. Each of the above cross-referenced patent applications is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION The present invention relates to the field of dentistry and more particularly relates to a dental prosthetic implant utilizing a polymer post. BACKGROUND OF THE INVENTION Throughout the span of the average individual's life they may through some means lose a tooth. The loss of a tooth may come by many different means such as an accident or decay. The loss of a tooth creates a gap which, on anterior surfaces, may seem aesthetically unpleasant and on a posterior tooth the loss of a chewing surface. The loss of more than one tooth will only exacerbate these problems. Once the tooth is ultimately lost the bone surrounding the tooth begins to deteriorate to the eventual loss of the socket. This creates a number of problems in creating a compatible prosthetic that is capable of replacing a lost tooth. The need for such a replacement tooth brought about the invention of the dental implant. The dental implant is a device that by design is intended to replace the function of a lost tooth. Commercially available dental implants usually have the following characteristics: a. Biocompatibility—the material that the implant is made from must be biocompatible. Many materials are not compatible with long-term implantation and are eventually rejected by the body. Therefore, the materials of choice are those that are the most inert—commercially available dental implants have settled upon the metal titanium as the material of choice. Since titanium forms an oxide coating that protects it from further rusting, it is ideal. Other noble metals such as platinum and gold would also be inert, but cost and physical properties would limit their use. Titanium is a good balance between inertness, physical properties, and cost, and is therefore the material most often used. b. Physical Properties—the material must exhibit sufficient strength and toughness in order to withstand the biting forces present during routine use. A weak biocompatible dental implant would simply break under the constant impact present while biting or chewing. The implant must be durable in that it must survive the constant impact and grinding forces of the teeth over the lifetime of the patient. Dental implants are usually designed with two pieces. The first one being the post implant and the second being the prosthetic itself. Post implants are designed to be fitted or screwed into the bone, as they are the anchors for the prosthetic. The clinician will usually drill a pilot hole into the bone prior to the insertion of the implant. The implant is then fitted or screwed into the pilot hole and allowed to heal before attaching the finished prosthetic. A clinician has options with respect to bone preparation; in some cases there might be insufficient bone with which to place an implant, therefore the clinician can place artificial bone under the tissue and grow bone if necessary. A clinician can choose the size and type of implant to best fit the patient's needs—if the patient has little bone into which to place an implant a clinician can choose a smaller implant. Though of course there is a trade off with regards to the size of the implant such that smaller implants will be able to withstand less force than a larger diameter implant. Also, the retention of smaller diameter posts within the bone becomes less as the diameter decreases. Therefore, the clinician must carefully choose the correct implant based upon the condition of the patient. At the end of the post is an abutment or collar to which the prosthetic is attached. The prosthetic is usually created in a lab and usually contains a metal attachment core with a ceramic surface that by design is made to look like a tooth. The finished prosthetic is snapped or connected to the implanted post and the patient at this point has a replacement tooth that is visibly and physically existent. As to the detailed physical properties of the post implant the intellectual community is divided into two camps. One camp is of the belief that a hard rigid post is superior to a flexible post. The belief being that a rigid post will reinforce the implant and also be more resistant to breakage since it does not undergo repeated flexing. The flexible post implant is argued by some to be superior as it is able to yield under unusual stress and resists being torn out of the socket. There is a need for dental implants whose physical properties can be adjusted for the specific needs of both camps. Metals such as titanium, whose only malleability properties are rigid, cannot fulfill these needs. The devices and materials of the present invention comprise the use of polymers whose physical properties can be adjusted to precise specifications. These devices comprise both flexible and rigid structures such that unique and custom implants can be produced. The adaptability and flexibility of polymers also allows for improved implant designs where metals would be completely incompatible. Instead of metals, the devices of the present invention comprise polymers, especially those polymers with exceptional physical properties and inertness. Polymers have advantages over metals in that they have the ability to flex and return to its original shape intact, whereas a metal will usually bend in similar circumstances. Metals are also limited in their method of manufacture in that they must be cast at high temperatures or each piece machined from a block. Polymers on the other hand can be molded at much lower temperatures and in machines that makes their mass production simple. Polymers have the advantage of being able to be compression, injection, blow, or thermoset molded and are generally amenable to other means of molding. Titanium implants are very expensive in part because their manufacture is difficult—e.g., the metal is expensive and the individual milling of each implant is time consuming and costly. The present invention comprises the use of the polymers as a means to create an effective, competitive post at much lower cost and requiring less intensive manual labor. SUMMARY OF THE INVENTION In view of the foregoing disadvantages inherent in the known types of dental implants, this invention provides a polymeric dental implant, including a polymeric implant post. As such, the general purpose of the present invention is to provide a new and improved polymeric dental implant that is manufactured to individually desired characteristics of rigidity, flexibility, durability, and other desired characteristics. To accomplish these objectives, the dental implants of the present invention comprise a polymeric post, the materials from which it is made being selected from the array of known and yet to be discovered polymers to match desired post and prosthetic characteristics. The more important features of the invention have thus been outlined in order that the more detailed description that follows may be better understood and in order that the present contribution to the art may better be appreciated. Additional features of the invention will be described hereinafter and will form the subject matter of the claims that follow. Many objects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fluted or barbed embodiment of the inventive polymeric implant; and FIG. 2 is a perspective view of a threaded embodiment of the inventive polymeric implant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to the drawings, the preferred embodiment of the polymeric dental implants is herein described. Plastics have an ability to be strong and deform without fracturing under stress. This inherent ability of some polymers to deform (flex/stretch) instead of fracturing is ideal for both an implant post and prosthetic. Plastics that are too brittle can be modified by plasticizers to impart more elasticity to the polymer in order to make them useful as an ideal implant material. Usable plastics can be a thermoplastic or a thermoset plastic. These polymers can be comprised of straight chain, co-polymeric, block or any combination of polymers incorporated into the same mass. Plastics can be chosen from the group of polymers such as: polyacrylates, polyamide-imide, phenolic, nylon, nitrile resins, fluoropolymers, copolyvidones (copovidones), epoxy, melamine-formaldehyde, diallyl phthalate, acetal, coumarone-indene, acrylics, acrylonitrile-butadiene-styrene, alkyds, cellulosics, polybutylene, polycarbonate, polycaprolactones, polyethylene, polyimides, polyphenylene oxide, polypropylene, polystyrene, polyurethanes, polyvinyl acetates, polyvinyl chloride, poly(vinyl alcohol-co ethylene), styrene acrylonitrile, sulfone polymers, saturated or unsaturated polyesters, urea-formaldehyde, or any like or useful plastics. Currently, the preferred plastics of the present invention include: Poly ether ether ketone (PEEK), Hi-lubricity nylons, impact resistant polymethylmethacrylate and fluoro-polymers. These polymers are high strength plastics that are resistant to wear and fracturing. They are also resistant to moisture and chemicals, and are biocompatible. The preferred plastic would also be selected from the group of thermoplastics that are capable of being injection molded, such that the entire implant can be injection molded. Various polymers can also be modified in order to maximize the warranted characteristics for a dental implant. This usually means incorporating the addition of a plasticizer or filler into the plastic. Plasticizers usually impart more elasticity to the polymer, therefore rendering them more resilient. A few examples of possible plasticizers include: mineral oil, triethyl citrate, acetyltriethyl citrate, lauric acid, modified vegetable oils, diacetylated monoglycerides, castor oil, sucrose diacetate hexaisobutyrate, triacetin, glycerin, liquid polyethylene glycols, liquid poly propylene glycols, propylene glycol, dimethyl phthalate, diethyl phthalate, dipropyl phthlate, dibutyl phthalate, dioctyl phthalate, polysorbates or any like or useful plasticizer. Fillers can also be incorporated into the plastic. Fillers usually modify the wear resistance, elasticity, fracture toughness and strength of the plastic. Fillers can be comprised of either powder or fiber, such as pieces of monofilament. A few examples of possible fillers would be silica, silica carbide, plastic monofilaments, carbon fiber, zirconia, alumina, borosilicate glass powder, radiopaque borosilicate powder, other radiopaque substances, titanium dioxide, zinc oxide, pigments, or any like or useful filler. Bioactice calcium containing compounds may also be utilized so as to facilitate bone growth and bonding to the surface of the post. The plastic, filler and plasticizer can be adjusted, for example, in type and relative concentration of the whole to impart essential characteristics to polymers that may be otherwise questionable as a useful dental prosthetic material. Pigments may also be added to the prosthetic in order to manufacture all the shades needed to match the teeth of the human race. The devices of the present invention can be sold as a complete kit, such that a polymer post is made to fit its custom corresponding polymer prosthetic. The polymer posts can be sold as a kit of many multiple sizes and diameters in order to provide sufficient choice for a variety of patient conditions. These polymer posts of various shapes and sizes would be pre-made by injection, compression, thermoset and any other polymer molding means. Upon selection, the dentist will drill a pilot hole in the bone and fit the implant into the hole by screwing, pressing or other means. Once the polymer post is implanted only the plastic abutment is exposed above the gum line and below the occlusal area in order to provide a protected area that is undisturbed during healing. During the healing interim, the dentist can have fabricated, by either a lab or device, the corresponding prosthetic. The custom shape of the prosthetic can be acquired by conventional impression material techniques and/or 3D scanning devices with corresponding model manipulation software. Once the design and shape of the post or prosthetic is known, the post or prosthetic can either be sent to a lab for milling and/or rapid prototype manufacture of the final custom post or prosthetic or the milling and/or rapid prototyping of the final post or prosthetic can be done in the dental office, since 3D milling machines are currently available to dental offices and as innovations to the art will tend to favor this option. Eventually, even the rapid prototyping of polymeric posts or prosthetics should become commonplace in a dental office, allowing the creation of a complete polymeric implant. The prosthetic itself may be made of similar polymers as the post, or entirely different ones, again as the practitioner determines need. In one embodiment, an impression is made of the post or prosthetic and the dimensions of the impression transferred to a numerical database. The dimensions in the database are then used to drive a numerically controlled milling or cutting machine to produce the post or prosthetic. In a second embodiment, an impression is made of the post or prosthetic and the dimensions of the impression transferred to a numerical database. The dimensions in the database are then used to drive a an additive manufacturing process wherein the process machine lays down successive layers of liquid, powder or sheet material to build up a model of the post or prosthetic using a series of thin layers or cross sections, the thin layers or cross sections being fused or joined together to create the final shape of the dental post or prosthetic. A polymeric post could be comprised of polymers that maximize the physical properties required in a retentive post such as strength and durability, and the prosthetic could be comprised of a different polymer that maximizes the physical properties needed in a prosthetic such as more wear resistance. From the above example it is very evident the increased advantages and options acquired by the devices and materials of the present invention. The post implant of the present invention can be designed with grooves and/or threads for increased retention. The polymer post can have threads of any size such that the post is intended to be screwed into the bone and gains retention by biting into the bone. Another design contemplates the use of ridges or grooves that are pushed into the pilot hole and merely hold passively until bone can grow around it. One preferred polymeric post is designed with flexible retentive grooves or barbs that flex inward during insertion and resist extraction by flexing outward and biting into the bone under extraction forces. This type of post design would be impossible for a rigid metal; as such metals cannot flex, the corresponding polymeric designs represent an advantage over prior art designs. Said posts are easily inserted and do not require a wrench or other tool to screw them in, they are simply set into place with sufficient force. Said design is superior to a screw type design, a screw type design must bite into the hard and soft tissue where the leading edge must cut into and displace room for an enlarging thread; this cuts and destroys bone in the process and the unattached excess tissue gets pushed between the threads. The body must remove this excess tissue before healing can begin; the flexible groove retentive post of the present invention avoids the cutting and displacement of the screw and minimizes the damage done to the tissues. The present invention contemplates the use of polymers that expand upon absorption of water such that they expand a surface roughened post into the sides of the bone for retention. Many different designs and methods can be devised with polymeric posts that are within the scope of this patent. In general, all post implant designs that comprise a polymer are within the scope of this patent. The present invention can be conveniently put together as a complete kit. The kit comprises polymeric posts of varying sizes and shapes to sufficiently cover the various conditions and anatomies of patients. The kit also comprises prosthetic blanks that can be inserted into a 3D milling machine for subsequent custom milling Referring now to the drawings, FIG. 1 illustrates a fluted or barbed polymeric implant 100 with flexible retentive grooves or barbs 110 that flex inward during insertion and resist extraction by flexing outward and biting into the bone under extraction forces. In one embodiment, the grooves and barbs include sharp or serrated edges 112 in order to maximize the bite into the corresponding bone for improved retention. FIG. 2 illustrates a screw type polymeric implant 200 having threads 210 . In one embodiment, the threads are slightly flexible, allowing them to flex during insertion in order to create a one-size-fits all implant, thereby permitting a screw-type implant of the present invention to be used on multiple sizes of holes or sockets. The threads 210 of the screw type implant 200 are preferably sharp and serrated at the edges 212 , permitting engagement with the bone for maximum post-operative retention. In both embodiments, the implant is inserted into the top of the canal and a ratchet is inserted onto the head 114 , 214 of the implant wherein the post is screwed or otherwise forced into the canal by twisting with said ratchet while gently applying downward pressure. Although the present invention has been described with reference to preferred embodiments, numerous modifications and variations can be made and still the result will come within the scope of the invention. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.	The present invention is a dental implant utilizing a polymeric dental post. The actual prosthetic portion of the implant may also be manufactured from a polymer. Various post designs are disclosed for setting and securing the post in a patient's jaw. Numerous polymers are disclosed and may be blended to achieve desired characteristics for both the post and prosthetic.	0
RELATED APPLICATIONS This application is a continuation of and claims priority to U.S. application Ser. No. 10/770,966 filed on Feb. 3, 2004 now U.S. Pat. No. 6,949,049, which claims priority from U.S. application Ser. No. 10/134,097 filed on Apr. 25, 2002 now U.S. Pat. No. 6,689,012, which in turn claims priority from U.S. Provisional Application No. 60/286,803, filed Apr. 26, 2001. The entire disclosure of each of those applications is hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The field of the invention relates generally to transmissions, and more particularly the invention relates to continuously variable transmissions. 2. Description of the Related Art The present invention relates to the field of continuously variable transmissions and includes several novel features and inventive aspects that have been developed and are improvements upon the prior art. In order to provide an infinitely variable transmission, various traction roller transmissions in which power is transmitted through traction rollers supported in a housing between torque input and output disks have been developed. In such transmissions, the traction rollers are mounted on support structures which, when pivoted, cause the engagement of traction rollers with the torque disks in circles of varying diameters depending on the desired transmission ratio. However, the success of these traditional solutions has been limited. For example, in one solution, a driving hub for a vehicle with a variable adjustable transmission ratio is disclosed. This method teaches the use of two iris plates, one on each side of the traction rollers, to tilt the axis of rotation of each of the rollers. However, the use of iris plates can be very complicated due to the large number of parts that are required to adjust the iris plates during transmission shifting. Another difficulty with this transmission is that it has a guide ring that is configured to be predominantly stationary in relation to each of the rollers. Since the guide ring is stationary, shifting the axis of rotation of each of the traction rollers is difficult. One improvement over this earlier design includes a shaft about which a driving member and a driven member rotate. The driving member and driven member are both mounted on the shaft and contact a plurality of power adjusters disposed equidistantly and radially about the shaft. The power adjusters are in frictional contact with both members and transmit power from the driving member to the driven member. A support member located concentrically over the shaft and between the power adjusters applies a force to keep the power adjusters separate so as to make frictional contact against the driving member and the driven member. A limitation of this design is the absence of means for generating an adequate axial force to keep the driving and driven members in sufficient frictional contact against the power adjusters as the torque load on the transmission changes. A further limitation of this design is the difficulty in shifting that results at high torque and very low speed situations as well as insufficient means for disengaging the transmission and coasting. Therefore, there is a need for a continuously variable transmission with an improved power adjuster support and shifting mechanism, means of applying proper axial thrust to the driving and driven members for various torque and power loads, and means of disengaging and reengaging the clutch for coasting. SUMMARY OF THE INVENTION The systems and methods have several features, no single one of which is solely responsible for its desirable attributes. Without limiting the scope as expressed by the claims that follow, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description of the Preferred Embodiments” one will understand how the features of the system and methods provide several advantages over traditional systems and methods. In one aspect, a continuously variable transmission is disclosed having a longitudinal axis, and a plurality of speed adjusters. Each speed adjuster has a tiltable axis of rotation is located radially outward from the longitudinal axis. Also provided are a drive disk that is annularly rotatable about the longitudinal axis and also contacts a first point on each of the speed adjusters and a support member that is also annularly rotatable about the longitudinal axis. A bearing disk is provided that is annularly rotatable about the longitudinal axis as well, and at least two axial force generators. The axial force generators are located between the drive disk and the bearing disk and each axial force generator is configured to apply an axial force to the drive disk. In another aspect, a bearing disk annularly rotatable about the longitudinal axis is disclosed along with a disengagement mechanism. The disengagement mechanism can be positioned between the bearing disk and the drive disk and is adapted to cause the drive disk to disengage the drive disk from the speed adjusters. In yet another aspect, an output disk or rotatable hub shell is disclosed along with a bearing disk that is annularly rotatable about the longitudinal axis of the transmission. A support member is included that is annularly rotatable about the longitudinal axis as well, and is adapted to move toward whichever of the drive disk or the output disk is rotating more slowly. In still another aspect, a linkage subassembly having a hook is disclosed, wherein the hook is attached to either the drive disk or the bearing disk. Included is a latch attached to either the drive disk or and the bearing disk. In another aspect, a plurality of spindles having two ends is disclosed, wherein one spindle is positioned in the bore of each speed adjuster and a plurality of spindle supports having a platform end and spindle end is provided. Each spindle support is operably engaged with one of the two ends of one of the spindles. Also provided is a plurality of spindle support wheels, wherein at least one spindle support wheel is provided for each spindle support. Included are annular first and second stationary supports each having a first side facing the speed adjusters and a second side facing away from the speed adjusters. Each of the first and second stationary supports have a concave surface on the first side and the first stationary support is located adjacent to the drive disk and the second stationary support is located adjacent to the driven disk. Also disclosed is a continuously variable transmission having a coiled spring that is positioned between the bearing disk and the drive disk. In another aspect, a transmission shifting mechanism is disclosed comprising a rod, a worm screw having a set of external threads, a shifting tube having a set of internal threads, wherein a rotation of the shifting tube causes a change in the transmission ratio, a sleeve having a set of internal threads, and a split shaft having a threaded end. In yet another aspect, a remote transmission shifter is disclosed comprising a rotatable handlegrip, a tether having a first end and a second end, wherein the first end is engaged with the handlegrip and the second end is engaged with the shifting tube. The handlegrip is adapted to apply tension to the tether, and the tether is adapted to actuate the shifting tube upon application of tension. These and other improvements will become apparent to those skilled in the art as they read the following detailed description and view the enclosed figures. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cutaway side view of an embodiment of the transmission. FIG. 2 is a partial end cross-sectional view taken on line II—II of FIG. 1 . FIG. 3 is a perspective view of a split shaft and two stationary supports of the transmission of FIG. 1 . FIG. 4 is a schematic cutaway side view of the transmission of FIG. 1 shifted into low. FIG. 5 is a schematic cutaway side view of the transmission of FIG. 1 shifted into high. FIG. 6 is a schematic side view of a ramp bearing positioned between two curved ramps of the transmission of FIG. 1 . FIG. 7 is a schematic side view of a ramp bearing positioned between two curved ramps of the transmission of FIG. 1 . FIG. 8 is a schematic side view of a ramp bearing positioned between two curved ramps of the transmission of FIG. 1 . FIG. 9 is a perspective view of the power adjuster sub-assembly of the transmission of FIG. 1 . FIG. 10 is a cutaway perspective view of the shifting sub-assembly of the transmission of FIG. 1 . FIG. 11 is a perspective view of a stationary support of the transmission of FIG. 1 . FIG. 12 is a perspective view of the screw and nut of the transmission of FIG. 1 . FIG. 13 is a schematic perspective view of the frame support of the transmission of FIG. 1 . FIG. 14 is a partial cutaway perspective view of the central ramps of the transmission of FIG. 1 . FIG. 15 is a perspective view of the perimeter ramps of the transmission of FIG. 1 . FIG. 16 is a perspective view of the linkage sub-assembly of the transmission of FIG. 1 . FIG. 17 is a perspective view of the disengagement mechanism sub-assembly of the transmission of FIG. 1 . FIG. 18 is a perspective view of the handlegrip shifter of the transmission of FIG. 1 . FIG. 19 is a cutaway side view of an alternative embodiment of the transmission of FIG. 1 . FIG. 20 is a cutaway side view of yet another alternative embodiment of the transmission of FIG. 1 . FIG. 21 is a perspective view of the transmission of FIG. 20 depicting a torsional brace. FIG. 22 is a perspective view of an alternative disengagement mechanism of the transmission of FIG. 1 . FIG. 23 is another perspective view of the alternative disengagement mechanism of FIG. 22 . FIG. 24 is a view of a sub-assembly of an alternative embodiment of the axial force generators of the transmission of FIG. 20 . FIG. 25 is a schematic cross sectional view of the splines and grooves of the axial force generators of FIG. 24 . FIG. 26 is a perspective view of an alternative disengagement mechanism of the transmission of FIG. 1 . FIG. 27 is a perspective view of the alternative disengagement mechanism of FIG. 26 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiments of the invention will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner simply because it is being utilized in conjunction with a detailed description of certain specific embodiments of the invention. Furthermore, embodiments of the invention may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the inventions herein described. The transmissions described herein are of the type that utilize speed adjuster balls with axes that tilt as described in U.S. patent application Ser. No. 09/695,757, filed on Oct. 24, 2000 and the information disclosed in that application is hereby incorporated by reference for all that it discloses. A drive (input) disk and a driven (output) disk are in contact with the speed adjuster balls. As the balls tilt on their axes, the point of rolling contact on one disk moves toward the pole or axis of the ball, where it contacts the ball at a circle of decreasing diameter, and the point of rolling contact on the other disk moves toward the equator of the ball, thus contacting the disk at a circle of increasing diameter. If the axis of the ball is tilted in the opposite direction, the disks respectively experience the converse situation. In this manner, the ratio of rotational speed of the drive disk to that of the driven disk, or the transmission ratio, can be changed over a wide range by simply tilting the axes of the speed adjuster balls. With reference to the longitudinal axis of embodiments of the transmission, the drive disk and the driven disk can be located radially outward from the speed adjuster balls, with an idler-type generally cylindrical support member located radially inward from the speed adjuster balls, so that each ball makes three-point contact with the inner support member and the outer disks. The drive disk, the driven disk, and the support member can all rotate about the same longitudinal axis. The drive disk and the driven disk can be shaped as simple disks or can be concave, convex, cylindrical or any other shape, depending on the configuration of the input and output desired. The rolling contact surfaces of the disks where they engage the speed adjuster balls can have a flat, concave, convex or other profile, depending on the torque and efficiency requirements of the application. Referring to FIGS. 1 and 2 , an embodiment of a continuously variable transmission 100 is disclosed. The transmission 100 is shrouded in a hub shell 40 , which functions as an output disk and is desirable in various applications, including those in which a vehicle (such as a bicycle or motorcycle) has the transmission contained within a driven wheel. The hub shell 40 can, in certain embodiments, be covered by a hub cap 67 . At the heart of the transmission 100 are a plurality of speed adjusters 1 that can be spherical in shape and are circumferentially spaced more or less equally or symmetrically around the centerline, or axis of rotation, of the transmission 100 . In the illustrated embodiment, eight speed adjusters 1 are used. However, it should be noted that more or fewer speed adjusters 1 can be used depending on the use of the transmission 100 . For example, the transmission may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more speed adjusters. The provision for more than 3, 4, or 5 speed adjusters can provide certain advantages including, for example, widely distributing the forces exerted on the individual speed adjusters 1 and their points of contact with other components of the transmission 100 . Certain embodiments in applications with low torque but a high transmission ratio can use few speed adjusters 1 but large speed adjusters 1 , while certain embodiments in applications where high torque and a transmission high transmission ratio can use many speed adjusters 1 and large speed adjusters 1 . Other embodiments in applications with high torque and a low transmission ratio can use many speed adjusters 1 and small speed adjusters 1 . Finally, certain embodiments in applications with low torque and a low transmission ratio may use few speed adjusters 1 and small speed adjusters 1 . Spindles 3 are inserted through holes that run through the center of each of the speed adjusters 1 to define an axis of rotation for each of the speed adjusters 1 . The spindles 3 are generally elongated shafts about which the speed adjusters 1 rotate, and have two ends that extend out of either end of the hole through the speed adjusters 1 . Certain embodiments will have cylindrical shaped spindles 3 , though any shape can be used. The speed adjusters 1 are mounted to freely rotate about the spindles 3 . In FIG. 1 , the axes of rotation of the speed adjusters 1 are shown in an approximately horizontal direction (i.e., parallel to the main axis of the transmission 100 ). FIGS. 1 , 4 and 5 , can be utilized to describe how the axes of the speed adjusters 1 can be tilted in operation to shift the transmission 100 . FIG. 4 depicts the transmission 100 shifted into a low transmission ratio, or low, while FIG. 5 depicts the transmission 100 shifted into a high transmission ratio, or high. Now also referring to FIGS. 9 and 10 , a plurality of spindle supports 2 are attached to the spindles 3 near each of the ends of the spindles 3 that extend out of the holes bored through the speed adjusters 1 , and extend radially inward from those points of attachment toward the axis of the transmission 100 . In one embodiment, each of the spindle supports 2 has a through bore that receives one end of one of the spindles 3 . The spindles 3 preferably extend through and beyond the spindle supports 2 such that they have an exposed end. In the embodiments illustrated, the spindles 3 advantageously have spindle rollers 4 coaxially and slidingly positioned over the exposed ends of the spindles 3 . The spindle rollers 4 are generally cylindrical wheels fixed axially on the spindles 3 outside of and beyond the spindle supports 2 and rotate freely about the spindles 3 . Referring also to FIG. 11 , the spindle rollers 4 and the ends of the spindles 3 fit inside grooves 6 that are cut into a pair of stationary supports 5 a , 5 b. Referring to FIGS. 4 , 5 and 11 , the stationary supports 5 a , 5 b are generally in the form of parallel disks annularly located about the axis of the transmission on either side of the power adjusters 1 . As the rotational axes of the speed adjusters 1 are changed by moving the spindle supports 2 radially out from the axis of the transmission 100 to tilt the spindles 3 , each spindle roller 4 fits into and follows a groove 6 cut into one of the stationary supports 5 a , 5 b . Any radial force, not rotational but a transaxial force, the speed adjusters 1 may apply to the spindles 3 is absorbed by the spindles 3 , the spindle rollers 4 and the sides 81 of the grooves 6 in the stationary supports 5 a , 5 b . The stationary supports 5 a , 5 b are mounted on a pair of split shafts 98 , 99 positioned along the axis of the transmission 100 . The split shafts 98 , 99 are generally elongated cylinders that define a substantial portion of the axial length of the transmission 100 and can be used to connect the transmission 100 to the object that uses it. Each of the split shafts 98 , 99 has an inside end near the middle of the transmission 100 and an outside end that extends out of the internal housing of the transmission 100 . The split shafts 98 , 99 are preferably hollow so as to house other optional components that may be implemented. The stationary supports 5 a , 5 b , each have a bore 82 , through which the split shafts 98 , 99 are inserted and rigidly attached to prevent any relative motion between the split shafts 98 , 99 and the stationary supports 5 a , 5 b . The stationary supports 5 a , 5 b are preferably rigidly attached to the ends of the split shafts 98 , 99 closest to the center of the transmission 100 . A stationary support nut 90 may be threaded over the split shaft 99 and tightened against the stationary support 5 b on corresponding threads of the stationary support 5 a , 5 b . The grooves 6 in the stationary supports 5 a , 5 b referred to above, extend from the outer circumference of the stationary supports 5 a , 5 b radially inwardly towards the split shafts 98 , 99 . In most embodiments, the groove sides 81 of the grooves 6 are substantially parallel to allow the spindle rollers 4 to roll up and down the groove sides 81 as the transmission 100 is shifted. Also, in certain embodiments, the depth of the grooves 6 is substantially constant at the circumference 9 of the stationary supports 5 a , 5 b , but the depth of the grooves 6 becomes shallower at points 7 closer to the split shaft 98 , 99 , to correspond to the arc described by the ends of the spindles 3 as they are tilted, and to increase the strength of the stationary supports 5 a , 5 b . As the transmission 100 is shifted to a lower or higher transmission ratio by changing the rotational axes of the speed adjusters 1 , each one of the pairs of spindle rollers 4 , located on the opposite ends of a single spindle 3 , move in opposite directions along their corresponding grooves 6 . Referring to FIGS. 9 and 11 , stationary support wheels 30 can be attached to the spindle supports 2 with stationary support wheel pins 31 or by any other attachment method. The stationary support wheels 30 are coaxially and slidingly mounted over the stationary support wheel pins 31 and secured with standard fasteners, such as ring clips for example. In certain embodiments, one stationary support wheel 30 is positioned on each side of a spindle 2 with enough clearance to allow the stationary support wheels 30 to roll radially on concave surfaces 84 of the stationary supports 5 a , 5 b when the transmission 100 is shifted. In certain embodiments, the concave surfaces 84 are concentric with the center of the speed adjusters 1 . Referring to FIGS. 2 , 3 , and 11 , a plurality of elongated spacers 8 are distributed radially about, and extend generally coaxially with, the axis of the transmission. The elongated spacers 8 connect the stationary supports 5 a to one another to increase the strength and rigidity of the internal structure of the transmission 100 . The spacers 8 are oriented generally parallel to one another, and in some embodiments, each one extends from a point at one stationary support 5 a near the outer circumference to a corresponding point on the other stationary support 5 b . The spacers 8 can also precisely fix the distance between the stationary supports 5 a , 5 b , align the grooves 6 of the stationary supports 5 a , 5 b , ensure that the stationary supports 5 a , 5 b are parallel, and form a connection between the split shafts 98 , 99 . In one embodiment, the spacers 8 are pressed through spacer holes 46 in the stationary supports 5 a , 5 b . Although eight spacers 8 are illustrated, more or less spacers 8 can be used. In certain embodiments, the spacers 8 are located between two speed adjusters 1 . Referring to FIGS. 1 , 3 , and 13 , the stationary support 5 a , in certain embodiments, is rigidly attached to a stationary support sleeve 42 located coaxially around the split shaft 98 , or alternately, is otherwise rigidly attached to or made an integral part of the split shaft 98 . The stationary sleeve 42 extends through the wall of the hub shell 40 and attaches to a frame support 15 . In some embodiments, the frame support 15 fits coaxially over the stationary sleeve 42 and is rigidly attached to the stationary sleeve 42 . The frame support 15 uses a torque lever 43 , in some embodiments, to maintain the stationary position of the stationary sleeve 42 . The torque lever 43 provides rotational stability to the transmission 100 by physically connecting the stationary sleeve 42 , via the frame support 15 , and therefore the rest of the stationary parts to a fixed support member of the item to which the transmission 100 is to be mounted. A torque nut 44 threads onto the outside of the stationary sleeve 42 to hold the torque lever 43 in a position that engages the frame support 15 . In certain embodiments, the frame support 15 is not cylindrical so as to engage the torque lever 43 in a positive manner thereby preventing rotation of the stationary sleeve 42 . For example, the frame support 15 could be a square of thickness equal to the torque lever 43 with sides larger than the stationary sleeve and with a hole cut out of its center so that the square may fit over the stationary sleeve 42 , to which it may then be rigidly attached. Additionally, the torque lever 43 could be a lever arm of thickness equal to that of the frame support 15 with a first end near the frame support 15 and a second end opposite the first. The torque lever 43 , in some embodiments, also has a bore through one of its ends, but this bore is a square and is a slightly larger square than the frame support 15 so the torque lever 43 could slide over the frame support 15 resulting in a rotational engagement of the frame support 15 and the torque lever 43 . Furthermore, the lever arm of the torque lever 43 is oriented so that the second end extends to attach to the frame of the bike, automobile, tractor or other application that the transmission 100 is used upon, thereby countering any torque applied by the transmission 100 through the frame support 15 and the stationary sleeve 42 . A stationary support bearing 48 fits coaxially around the stationary sleeve 42 and axially between the outside edge of the hub shell 40 and the torque lever 43 . The stationary support bearing 48 supports the hub shell 40 , permitting the hub shell 40 to rotate relative to the stationary support sleeve 42 . Referring to FIGS. 1 and 10 , in some embodiments, shifting is manually activated by rotating a rod 10 , positioned in the hollow split shaft 98 . A worm screw 11 , a set of male threads in some embodiments, is attached to the end of the rod 10 that is in the center of the transmission 100 , while the other end of the rod 10 extends axially to the outside of the transmission 100 and has male threads affixed to its outer surface. In one embodiment, the worm screw 11 is threaded into a coaxial sleeve 19 with mating threads, so that upon rotation of the rod 10 and worm screw 11 , the sleeve 19 moves axially. The sleeve 19 is generally in the shape of a hollow cylinder that fits coaxially around the worm screw 11 and rod 10 and has two ends, one near stationary support 5 a and one near stationary support 5 b . The sleeve 19 is affixed at each end to a platform 13 , 14 . The two platforms 13 , 14 are each generally of the form of an annular ring with an inside diameter, which is large enough to fit over and attach to the sleeve 19 , and is shaped so as to have two sides. The first side is a generally straight surface that dynamically contacts and axially supports the support member 18 via two sets of contact bearings 17 a , 17 b . The second side of each platform 13 , 14 is in the form of a convex surface. The platforms 13 , 14 are each attached to one end of the outside of the sleeve 19 so as to form an annular trough around the circumference of the sleeve 19 . One platform 13 is attached to the side nearest stationary support 5 a and the other platform 14 is attached to the end nearest stationary support 5 b . The convex surface of the platforms 13 , 14 act as cams, each contacting and pushing multiple shifting wheels 21 . To perform this camming function, the platforms 13 , 14 preferably transition into convex curved surfaces 97 near their perimeters (farthest from the split shafts 98 , 99 ), that may or may not be radii. This curve 97 contacts with the shifting wheels 21 so that as the platforms 13 , 14 move axially, a shifting wheel 21 rides along the platform 13 , 14 surface in a generally radial direction forcing the spindle support 2 radially out from, or in toward, the split shaft 98 , 99 , thereby changing the angle of the spindle 3 and the rotation axis of the associated speed adjuster 1 . In certain embodiments, the shifting wheels 21 fit into slots in the spindle supports 2 at the end nearest the centerline of the transmission 100 and are held in place by wheel axles 22 . Still referring to FIGS. 1 and 10 , a support member 18 is located in the trough formed between the platforms 13 , 14 and sleeve 19 , and thus moves in unison with the platforms 13 , 14 and sleeve 19 . In certain embodiments, the support member 18 is generally of one outside diameter and is generally cylindrical along the center of its inside diameter with a bearing race on each edge of its inside diameter. In other embodiments, the outer diameter of the support member 18 can be non-uniform and can be any shape, such as ramped or curved. The support member 18 has two sides, one near one of the stationary supports 5 a and one near the other stationary support 5 b . The support member 18 rides on two contact bearings 17 a , 17 b to provide rolling contact between the support member 18 and the sleeve 19 . The contact bearings 17 a , 17 b are located coaxially around the sleeve 19 where the sleeve 19 intersects the platforms 13 , 14 allowing the support member 18 to freely rotate about the axis of the transmission 100 . The sleeve 19 is supported axially by the worm screw 11 and the rod 10 and therefore, through this configuration, the sleeve 19 is able to slide axially as the worm screw 11 positions it. When the transmission 100 is shifted, the sleeve 19 moves axially, and the bearings 17 a , 17 b , support member 18 , and platforms 13 , 14 , which are all attached either dynamically or statically to the sleeve, move axially in a corresponding manner. In certain embodiments, the rod 10 is attached at its end opposite the worm screw 11 to a shifting tube 50 by a rod nut 51 , and a rod flange 52 . The shifting tube 50 is generally in the shape of a tube with one end open and one end substantially closed. The open end of shifting tube 50 is of a diameter appropriate to fit over the end of the split shaft 98 that extends axially out of the center of the transmission 100 . The substantially closed end of the shifting tube 50 has a small bore through it so that the end of the rod 10 that is opposite of the worm screw 11 can pass through it as the shifting tube 50 is placed over the outside of the split shaft 98 . The substantially closed end of the shifting tube 50 can then be fixed in axial place by the rod nut 51 , which is fastened outside of the shifting tube 50 , and the rod flange 52 , which in turn is fastened inside of the shifting tube's 50 substantially closed end, respectively. The shifting tube 50 can, in some embodiments, be rotated by a cable 53 attached to the outside of the shifting tube 50 . The cable 53 , in these embodiments, is attached to the shifting tube 50 with a cable clamp 54 and cable screw 56 , and then wrapped around the shifting tube 50 so that when tension is applied to the cable 53 a moment is developed about the center of the axis of the shifting tube 50 causing it to rotate. The rotation of shifting tube 50 may alternately be caused by any other mechanism such as a rod, by hand rotation, a servo-motor or other method contemplated to rotate the rod 10 . In certain embodiments, when the cable 53 is pulled so that the shifting tube 50 rotates clockwise on the split shaft 98 , the worm screw 11 rotates clockwise, pulling the sleeve 19 , support member 18 and platforms 13 , 14 , axially toward the shifting tube 50 and shifting the transmission 100 towards a low transmission ratio. A worm spring 55 , as illustrated in FIG. 3 , that can be a conical coiled spring capable of producing compressive and torsional force, attached at the end of the worm screw 11 , is positioned between the stationary support 5 b and the platform 14 and resists the shifting of the transmission 100 . The worm spring 55 is designed to bias the shifting tube 50 to rotate so as to shift the transmission 100 towards a low transmission ratio in some embodiments and towards a high transmission ratio in other embodiments. Referring to FIGS. 1 , 10 , and 11 , axial movement of the platforms 13 , 14 , define the shifting range of the transmission 100 . Axial movement is limited by inside faces 85 on the stationary supports 5 a , 5 b , which the platforms 13 , 14 contact. At an extreme high transmission ratio, platform 14 contacts the inside face 85 on one of the stationary supports 5 a , 5 b , and at an extreme low transmission ratio, the platform 13 contacts the inside face 85 on the other one of the stationary supports 5 a , 5 b . In many embodiments, the curvature of the convex radii of the platforms 13 , 14 , are functionally dependant on the distance from the center of a speed adjuster 1 to the center of the wheel 21 , the radius of the wheel 21 , the distance between the two wheels 21 that are operably attached to each speed adjuster 1 , and the angle of tilt of the speed adjuster 1 axis. Although a left hand threaded worm screw 11 is disclosed, a right hand threaded worm screw 11 , the corresponding right hand wrapped shifting tube 50 , and any other combination of components just described that is can be used to support lateral movement of the support member 18 and platforms 13 , 14 , can be used. Additionally, the shifting tube 50 can have internal threads that engage with external threads on the outside of the split shaft 98 . By adding this threaded engagement, the shifting tube 50 will move axially as it rotates about the split shaft 98 causing the rod 10 to move axially as well. This can be employed to enhance the axial movement of the sleeve 19 by the worm screw 11 so as to magnify the effects of rotating the worm screw 11 to more rapidly shift the gear ratio or alternatively, to diminish the effects of rotating the worm screw 11 so as to slow the shifting process and produce more accurate adjustments of the transmission 100 . Referring to FIGS. 10 and 18 , manual shifting may be accomplished by use of a rotating handlegrip 132 , which can be coaxially positioned over a stationary tube, a handlebar 130 , or some other structural member. In certain embodiments, an end of the cable 53 is attached to a cable stop 133 , which is affixed to the rotating handlegrip 132 . In some embodiments, internal forces of the transmission 100 and the conical spring 55 tend to bias the shifting of the transmission towards a lower transmission ratio. As the rotating handlegrip 132 is rotated by the user, the cable 53 , which can be wrapped along a groove around the rotating handlegrip 132 , winds or unwinds depending upon the direction of rotation of the cable 53 , simultaneously rotating the shifting tube 50 and shifting the transmission 100 towards a higher transmission ratio. A set of ratchet teeth 134 can be circumferentially positioned on one of the two sides of the rotating handlegrip 132 to engage a mating set of ratchet teeth on a first side of a ratcheted tube 135 , thereby preventing the rotating handlegrip 132 from rotating in the opposite direction. A tube clamp 136 , which can bean adjustable screw allowing for variable clamping force, secures the ratcheted tube 135 to the handlebar 130 . When shifting in the opposite direction, the rotating handlegrip 132 , is forcibly rotated in the opposite direction toward a lower transmission ratio, causing the tube clamp 136 to rotate in unison with the rotating handlegrip 132 . A handlebar tube 137 , positioned proximate to the ratcheted tube 135 , on a side opposite the ratchet teeth 134 , is rigidly clamped to the handlebar 130 with a tube clamp 138 , thereby preventing disengagement of the ratcheted tube 135 from the ratchet teeth 134 . A non-rotating handlegrip 131 is secured to the handlebar 130 and positioned proximate to the rotating handlegrip 132 , preventing axial movement of the rotating handlegrip 132 and preventing the ratchet teeth 134 from becoming disengaged from the ratcheted tube 135 . Now referring to embodiments illustrated by FIGS. 1 , 9 , and 11 , a one or more stationary support rollers 30 can be attached to each spindle support 2 with a roller pin 31 that is inserted through a hole in each spindle support 2 . The roller pins 31 are of the proper size and design to allow the stationary support rollers 30 to rotate freely over each roller pin 31 . The stationary support rollers 30 roll along concave curved surfaces 84 on the sides of the stationary supports 5 a , 5 b that face the speed adjusters 1 . The stationary support rollers 30 provide axial support to prevent the spindle supports 2 from moving axially and also to ensure that the spindles 2 tilt easily when the transmission 100 is shifted. Referring to FIGS. 1 , 12 , 14 , and 17 , a three spoked drive disk 34 , located adjacent to the stationary support 5 b , partially encapsulates but generally does not contact the stationary support 5 b . The drive disk 34 may have two or more spokes or may be a solid disk. The spokes reduce weight and aid in assembly of the transmission 100 ine embodiments using them, however a solid disk can be used. The drive disk 34 has two sides, a first side that contacts with the speed adjusters 1 , and a second side that faces opposite of the first side. The drive disk 34 is generally an annular disk that fits coaxially over, and extends radially from, a set of female threads or nut 37 at its inner diameter. The outside diameter of the drive disk 34 is designed to fit within the hub shell 40 , if the hub shell 40 employed is the type that encapsulates the speed adjusters 1 and the drive disk 34 , and engages with the hub cap 67 . The drive disk 34 is rotatably coupled to the speed adjusters 1 along a circumferential bearing surface on the lip of the first side of the drive disk 34 . As mentioned above, some embodiments of the drive disk 34 have a set of female threads 37 , or a nut 37 , at its center, and the nut 37 is threaded over a screw 35 , thereby engaging the drive disk 34 with the screw 35 . The screw 35 is rigidly attached to a set of central screw ramps 90 that are generally a set of raised surfaces on an annular disk that is positioned coaxially over the split shaft 99 . The central screw ramps 90 are driven by a set of central drive shaft ramps 91 , which are similarly formed on a generally annular disk. The ramp surfaces of the central drive ramps 91 and the central screw ramps 90 can be linear, but can be any other shape, and are in operable contact with each other. The central drive shaft ramps 91 , coaxially and rigidly attached to the drive shaft 69 , impart torque and an axial force to the central screw ramps 90 that can then be transferred to the drive disk 34 . A central drive tension member 92 , positioned between the central drive shaft ramps 91 and the central screw ramps 90 , produces torsional and/or compressive force, ensuring that the central ramps 90 , 91 are in contact with one another. Still referring to FIGS. 1 , 12 , 14 , and 17 , the screw 35 , which is capable of axial movement, can be biased to move axially away from the speed adjusters 1 with an annular thrust bearing 73 that contacts a race on the side of the screw 35 that faces the speed adjusters 1 . An annular thrust washer 72 , coaxially positioned over the split shaft 99 , contacts the thrust bearing 73 and can be pushed by a pin 12 that extends through a slot in the split shaft 99 . A compression member 95 capable of producing a compressive force is positioned in the bore of the hollow split shaft 99 at a first end. The compression member 95 , which may be a spring, contacts the pin 12 on one end, and at a second end contacts the rod 10 . As the rod 10 is shifted towards a higher transmission ratio and moves axially, it contacts the compression member 95 , pushing it against the pin 12 . Internal forces in the transmission 100 will bias the support member 18 to move towards a high transmission ratio position once the transmission ratio goes beyond a 1:1 transmission ratio towards high and the drive disk 34 rotates more slowly than the hub shell 40 . This bias pushes the screw 35 axially so that it either disconnects from the nut 37 and no longer applies an axial force or a torque to the drive disk 34 , or reduces the force that the screw 35 applies to the nut 37 . In this situation, the percentage of axial force applied to the drive disk 34 by the perimeter ramps 61 increases. It should be noted that the internal forces of the transmission 100 will also bias the support member 18 towards low once the support member 18 passes beyond a position for a 1:1 transmission ratio towards low and the hub shell 40 rotates more slowly than the drive disk 34 . This beneficial bias assists shifting as rpm's drop and torque increases when shifting into low. Still referring to FIGS. 1 , 12 , 14 , and 17 , the drive shaft 69 , which is a generally tubular sleeve having two ends and positioned coaxial to the outside of the split shaft 99 , has at one end the aforementioned central drive shaft ramps 91 attached to it, while the opposite end faces away from the drive disk 34 . In certain embodiments, a bearing disk 60 is attached to and driven by the drive shaft 69 . The bearing disk 60 can be splined to the drive shaft 69 , providing for limited axial movement of the bearing disk 60 , or the bearing disk 60 can be rigidly attached to the drive shaft 69 . The bearing disk 60 is generally a radial disk coaxially mounted over the drive shaft 69 extending radially outward to a radius generally equal to that of the drive disk 34 . The bearing disk 60 is mounted on the drive shaft 69 in a position near the drive disk 34 , but far enough away to allow space for a set of perimeter ramps 61 , associated ramp bearings 62 , and a bearing race 64 , all of which are located between the drive disk 34 and the bearing disk 67 . In certain embodiments, the plurality of perimeter ramps 61 can be concave and are rigidly attached to the bearing disk 60 on the side facing the drive disk 34 . Alternatively, the perimeter ramps 61 can be convex or linear, depending on the use of the transmission 100 . Alternatively, the bearing race 64 , can be replaced by a second set of perimeter ramps 97 , which may also be linear, convex, or concave, and which are rigidly attached to the drive disk 34 on the side facing the bearing disk 60 . The ramp bearings 62 are generally a plurality of bearings matching in number the perimeter ramps 61 . Each one of the plurality of ramp bearings 62 is located between one perimeter ramp 61 and the bearing race 64 , and is held in its place by a compressive force exerted by the ramps 61 and also by a bearing cage 63 . The bearing cage 63 is an annular ring coaxial to the split shaft 99 and located axially between the concave ramps 61 and convex ramps 64 . The bearing cage 63 has a relatively large inner diameter so that the radial thickness of the bearing cage 63 is only slightly larger than the diameter of the ramp bearings 62 to house the ramp bearings 62 . Each of the ramp bearings 62 fits into a hole that is formed in the radial thickness of the bearing cage 63 and these holes, together with the previously mentioned compressive force, hold the ramp bearings 62 in place. The bearing cage 63 , can be guided into position by a flange on the drive disk 34 or the bearing disk 60 , which is slightly smaller than the inside diameter of the bearing cage 63 . Referring to FIGS. 1 , 6 , 7 , 8 , and 15 , the bearing disk 60 , the perimeter ramps 61 , and a ramp bearing 62 of one embodiment are depicted. Referring specifically to FIG. 6 , a schematic view shows a ramp bearing 62 contacting a concave perimeter ramp 61 , and a second convex perimeter ramp 97 . Referring specifically to FIG. 7 , a schematic view shows the ramp bearing 62 , the concave perimeter ramp 61 , and the second convex perimeter ramp 97 of FIG. 6 at a different torque or transmission ratio. The position of the ramp bearings 62 on the perimeter ramps 61 depicted in FIG. 7 produces less axial force than the position of the ramp bearings 62 on the perimeter ramps 61 depicted in FIG. 6 . Referring specifically to FIG. 8 , a ramp bearing 62 is shown contacting a convex perimeter ramp 61 , and a concave second perimeter ramp 97 in substantially central positions on those respective ramps. It should be noted that changes in the curves of the perimeter ramps 61 , 97 change the magnitude of the axial force applied to the power adjusters 1 at various transmission ratios, thereby maximizing efficiency in different gear ratios and changes in torque. Depending on the use for the transmission 100 , many combinations of curved or linear perimeter ramps 61 , 97 can be used. To simplify operation and reduce cost, in some applications one set of perimeter ramps may be eliminated, such as the second set of perimeter tramps 97 , which are then replaced by a bearing race 64 . To further reduce cost, the set of perimeter ramps 61 may have a linear inclination. Referring to FIG. 1 , a coiled spring 65 having two ends wraps coaxially around the drive shaft 69 and is attached at one end to the bearing disk 60 and at its other end to the drive disk 34 . The coiled spring 65 provides force to keep the drive disk 34 in contact with the speed adjusters 1 and biases the ramp bearings 62 up the perimeter ramps 61 . The coiled spring 65 is designed to minimize the axial space within which it needs to operate and, in certain embodiments, the cross section of the coiled spring 65 is a rectangle with the radial length greater than the axial length. Referring to FIG. 1 , the bearing disk 60 preferably contacts an outer hub cap bearing 66 on the bearing disk 60 side that faces opposite the concave ramps 61 . The outer hub cap bearing 66 can be an annular set of roller bearings located radially outside of, but coaxial with, the centerline of the transmission 100 . The outer hub cap bearing 66 is located radially at a position where it may contact both the hub cap 67 and the bearing disk 60 to allow their relative motion with respect to one another. The hub cap 67 is generally in the shape of a disk with a hole in the center to fit over the drive shaft 69 and with an outer diameter such that it will fit within the hub shell 40 . The inner diameter of the hub cap engages with an inner hub cap bearing 96 that is positioned between the hub cap 67 and the drive shaft 69 and maintains the radial and axial alignment of the hub cap 67 and the drive shaft 69 with respect to one another. The edge of the hub cap 67 at its outer diameter can be threaded so that the hub cap 67 can be threaded into the hub shell 40 to encapsulate much of the transmission 100 . A sprocket or pulley 38 or other drive train adapter, such as gearing for example, can be rigidly attached to the rotating drive shaft 69 to provide the input rotation. The drive shaft 69 is maintained in its coaxial position about the split shaft 99 by a cone bearing 70 . The cone bearing 70 is an annular bearing mounted coaxially around the split shaft 99 and allows rolling contact between the drive shaft 69 and the split shaft 99 . The cone bearing 70 may be secured in its axial place by a cone nut 71 which threads onto the split shaft 99 or by any other fastening method. In operation of certain embodiments, an input rotation from the sprocket or pulley 38 is transmitted to the drive shaft 69 , which in turn rotates the bearing disk 60 and the plurality of perimeter ramps 61 causing the ramp bearings 62 to roll up the perimeter ramps 61 and press the drive disk 34 against the speed adjusters 1 . The ramp bearings 62 also transmit rotational energy to the drive disk 34 as they are wedged in between, and therefore transmit rotational energy between, the perimeter ramps 61 and the convex ramps 64 . The rotational energy is transferred from the drive disk 34 to the speed adjusters 1 , which in turn rotate the hub shell 40 providing the transmission 100 output rotation and torque. Referring to FIG. 16 , a latch 115 rigidly attaches to the side of the drive disk 34 that faces the bearing disk 60 and engages a hook 114 that is rigidly attached to a first of two ends of a hook lever 113 . The engaging area under the latch 115 opening is larger than the width of the hook 114 and provides extra room for the hook 114 to move radially, with respect to the axis, within the confines of the latch 114 when the drive disk 34 and the bearing disk 60 move relative to each other. The hook lever 113 is generally a longitudinal support member for the hook 114 and at its second end, the hook lever 113 has an integral hook hinge 116 that engages with a middle hinge 119 via a first hinge pin 111 . The middle hinge 119 is integral with a first end of a drive disk lever 112 , a generally elongated support member having two ends. On its second end, the drive disk lever 112 has an integral drive disk hinge 117 , which engages a hinge brace 110 via the use of a second hinge pin 118 . The hinge brace 110 is generally a base to support the hook 114 , the hook lever 113 , the hook hinge 116 , the first hinge pin 111 , the middle hinge 119 , the drive disk lever 112 the second hinge pin 118 , and the drive disk hinge 117 , and it is rigidly attached to the bearing disk 60 on the side facing the drive disk 34 . When the latch 73 and hook 72 are engaged the ramp bearings 62 are prevented from rolling to an area on the perimeter ramps 61 that does not provide the correct amount of axial force to the drive disk 34 . This ensures that all rotational force applied to the ramp bearings 62 by perimeter ramps 61 is transmitted to the drive disk 34 . Referring to FIGS. 1 and 17 , a disengagement mechanism for one embodiment of the transmission 100 is described to disengage the drive disk 34 from the speed adjusters 1 in order to coast. On occasions that input rotation to the transmission 100 ceases, the sprocket or pulley 38 stops rotating but the hub shell 40 and the speed adjusters 1 can continue to rotate. This causes the drive disk 34 to rotate so that the set of female threads 37 in the bore of the drive disk 34 wind onto the male threaded screw 35 , thereby moving the drive disk 34 axially away from the speed adjusters 1 until the drive disk 34 no longer contacts the speed adjusters 1 . A toothed rack 126 , rigidly attached to the drive disk 34 on the side facing the bearing disk 60 , has teeth that engage and rotate a toothed wheel 124 as the drive disk 34 winds onto the screw 35 and disengages from the power adjusters 1 . The toothed wheel 124 , has a bore in its center, through which a toothed wheel bushing 121 is located, providing for rotation of the toothed wheel 124 . Clips 125 that are coaxially attached over the toothed wheel bushing 121 secure the toothed wheel 124 in position, although any means of fastening may be used. A preloader 120 , coaxially positioned over and clamped to the central drive shaft ramps 91 , extends in a direction that is radially outward from the center of the transmission 100 . The preloader 120 , of a resilient material capable of returning to its original shape when flexed, has a first end 128 and a second end 127 . The first end of the preloader 128 extends through the toothed wheel bushing 121 and terminates in the bearing cage 63 . The first end of the preloader 128 biases the bearing cage 63 and ramp bearings 62 up the ramps 61 , ensuring contact between the ramp bearings 62 and the ramps 61 , and also biases the toothed wheel 124 against the toothed rack 126 . A pawl 123 , engages the toothed wheel 124 , and in one embodiment engages the toothed wheel 124 on a side substantially opposite the toothed rack 126 . The pawl 123 has a bore through which a pawl bushing 122 passes, allowing for rotation of the pawl 123 . Clips 125 , or other fastening means secure the pawl 123 to the pawl bushing 121 . A pawl spring 122 biases rotation of the pawl 123 to engage the toothed wheel 124 , thereby preventing the toothed wheel 124 from reversing its direction of rotation when the drive disk 34 winds onto the screw 35 . The pawl bushing 121 is positioned over a second end of the preloader 127 , which rotates in unison with the drive shaft 69 . Referring again to FIG. 1 , a coiled spring 65 , coaxial with and located around the drive shaft 69 , is located axially between and attached by pins or other fasteners (not shown) to both the bearing disk 60 at one end and drive disk 34 at the other end. In certain embodiments, the coiled spring 65 replaces the coiled spring of the prior art so as to provide more force and take less axial space in order to decrease the overall size of the transmission 100 . In some embodiments, the coiled spring 65 is produced from spring steel wire with a rectangular profile that has a radial length or height greater than its axial length or width. During operation of the transmission 100 , the coiled spring 65 ensures contact between the speed adjusters 1 and the drive disk 34 . However, once the drive disk 34 has disengaged from the speed adjusters 1 , the coiled spring 65 is prevented from winding the drive disk 34 so that it again contacts the speed adjusters 1 by the engagement of the toothed wheel 124 and the pawl 123 . When the input sprocket, gear, or pulley 38 , resumes its rotation, the pawl 123 also rotates, allowing the toothed wheel 124 to rotate, thus allowing the drive disk 34 to rotate and unwind from the screw 35 due to the torsional force created by the coiled spring 65 . Relative movement between the pawl 123 and the toothed wheel 124 is provided by the fact that the first end of the preloader 128 rotates at approximately half the speed as the second end of the preloader 127 because the first end of the preloader 128 is attached to the bearing cage 63 . Also, because the ramp bearings 62 are rolling on the perimeter ramps 61 of the bearing disk 60 , the bearing cage 63 will rotate at half the speed as the bearing disk 60 . Referring now to FIG. 19 , an alternative embodiment of the transmission 100 of FIG. 1 is disclosed. In this embodiment, an output disk 201 replaces the hub shell 40 of the transmission 100 illustrated in FIG. 1 . Similar to the drive disk 34 , the output disk 201 contacts, and is rotated by, the speed adjusters 1 . The output disk 201 is supported by an output disk bearing 202 that contacts both the output disk 201 and a stationary case cap 204 . The case cap 204 is rigidly attached to a stationary case 203 with case bolts 205 or any other fasteners. The stationary case 203 can be attached to a non-moving object such as a frame or to the machine for which its use is employed. A gear, sprocket, or pulley 206 is attached coaxially over and rigidly to the output disk 201 outside of the case cap 204 and stationary case 203 . Any other type of output means can be used however, such as gears for example. A torsional brace 207 can be added that rigidly connects the split shaft 98 to the case cap 204 for additional support. Referring now to FIGS. 20 and 21 , an alternative embodiment of the transmission 100 of FIG. 1 is disclosed. A stationary support race 302 is added on a side of stationary support 5 a facing away from the speed adjusters 1 and engages with a stationary support bearing 301 and a rotating hub shell race 303 to maintain correct alignment of the stationary support 5 a with respect to the rotating hub shell 40 . A torsional brace 304 is rigidly attached to the stationary support 5 a and can then be rigidly attached to a stationary external component to prevent the stationary supports 5 a , 5 b from rotating during operation of the transmission 300 . A drive shaft bearing 306 is positioned at an end of the drive shaft 69 facing the speed adjusters 1 and engages a drive shaft race 307 formed in the same end of the drive shaft 69 and a split shaft race 305 formed on a radially raised portion of the split shaft 99 to provide additional support to the drive shaft 69 and to properly position the drive shaft 69 relative to the stationary supports 5 a , 5 b. Referring now to FIGS. 22 and 23 , an alternative disengagement mechanism 400 of the transmission 100 of FIG. 1 is disclosed. A toothed wheel 402 is coaxially positioned over a wheel bushing 408 and secured in position with a clip 413 or other fastener such that it is capable of rotation. The wheel bushing 408 is coaxially positioned over the first end of a preloader 405 having first and second ends (both not separately identified in FIGS. 22 , and 23 ). The preloader 405 clamps resiliently around the central drive shaft ramps 91 . The first end of the preloader 405 extends into the bearing cage 63 , biasing the bearing cage 63 up the perimeter ramps 61 . Also positioned over the wheel bushing 408 is a lever 401 that rotates around the wheel bushing 408 and that supports a toothed wheel pawl 411 and a pinion pawl 409 . The toothed wheel pawl 411 engages the toothed wheel 402 to control its rotation, and is positioned over a toothed wheel bushing 414 that is pressed into a bore in the lever 401 . A toothed wheel pawl spring 412 biases the toothed wheel pawl 411 against the toothed wheel 402 . The pinion pawl 409 , positioned substantially opposite the toothed wheel pawl 411 on the lever 401 , is coaxially positioned over a pinion pawl bushing 415 that fits into another bore in the lever 401 and provides for rotational movement of the pinion pawl 409 . A pinion pawl spring 410 biases the pinion pawl 409 against a pinion 403 . Referring now to FIGS. 1 , 22 and 23 , the pinion 403 has a bore at its center and is coaxially positioned over a first of two ends of a rod lever 404 . The rod lever is an elongated lever that engages the pinion pawl 409 during coasting until input rotation of the sprocket, pulley, or gear 38 resumes. A bearing disk pin 406 that is affixed to the bearing disk 60 contacts a second end of the rod lever 404 , upon rotation of the bearing disk 60 , thereby pushing the rod lever 404 against a drive disk pin 407 , which is rigidly attached to the drive disk 34 . This action forces the first end of the rod lever 404 to swing away from the toothed wheel 402 , temporarily disconnecting the pinion 403 from the toothed wheel 402 , allowing the toothed wheel 402 to rotate. A lever hook 401 is attached to the lever 401 and contacts a latch (not shown) on the drive disk 34 and is thereby pushed back as the coiled spring 65 biases the drive disk 34 to unwind and contact the speed adjusters 1 . During occasions that the input rotation of the sprocket, pulley, or gear 38 ceases, and the speed adjusters 1 continue to rotate, the drive disk 34 winds onto the screw 35 and disengages from the speed adjusters 1 . As the drive disk 34 rotates, the drive disk pin 407 disengages from the rod lever 404 , which then swings the pinion 403 into contact with the toothed wheel 402 , preventing the drive disk 34 from re-engaging the speed adjusters 1 . Referring to FIGS. 24 and 25 , a sub-assembly of an alternative set of axial force generators 500 of the transmission 300 of FIG. 20 is disclosed. When rotated by the input sprocket, gear, or pulley 38 , a splined drive shaft 501 rotates the bearing disk 60 , which may have grooves 505 in its bore to accept and engage the splines 506 of the splined drive shaft 501 . The central drive shaft ramps 508 are rigidly attached to the bearing disk 60 or the splined drive shaft 501 and rotate the central screw ramps 507 , both of which have bores that clear the splines 506 of the splined drive shaft 501 . The central tension member 92 (illustrated in FIG. 1 ) is positioned between the central drive shaft ramps 508 and the central screw ramps 507 . A grooved screw 502 having a grooved end and a bearing end is rotated by the central screw ramps 90 and has grooves 505 on its bearing end that are wider than the splines 506 on the splined drive shaft 501 to provide a gap between the splines 506 and the grooves 505 . This gap between the splines 506 and the grooves 505 allows for relative movement between the grooved screw 502 and/or bearing disk 60 and the splined drive shaft 501 . On occasions when the grooved screw 502 is not rotated by the central drive shaft ramps 508 and the central screw ramps 507 , the splines 506 of the splined drive shaft 501 contact and rotate the grooves 505 on the grooved screw 502 , thus rotating the grooved screw 502 . An annular screw bearing 503 contacts a race on the bearing end of the grooved screw 502 and is positioned to support the grooved screw 502 and the splined drive shaft 501 relative to the axis of the split shaft 99 . The bore of the grooved screw 502 is slightly larger than the outside diameter of the splined drive shaft 501 to allow axial and rotational relative movement of the grooved screw 502 . A screw cone race 504 contacts and engages the annular screw bearing 503 and has a hole perpendicular to its axis to allow insertion of a pin 12 . The pin 12 engages the rod 10 , which can push on the pin 12 and move the grooved screw 502 axially, causing it to disengage from, or reduce the axial force that it applies to, the nut 37 . Referring to FIG. 26 , an alternative disengagement means 600 of the disengagement means 400 of FIGS. 22 and 23 is disclosed. The lever 401 is modified to eliminate the T-shape used to mount both the pinion pawl 409 and the toothed wheel pawl 411 so that the new lever 601 has only the toothed wheel pawl 411 attached to it. A second lever 602 , having a first end and a second end. The pinion pawl 409 is operably attached to the first end of the second lever 602 . The second lever 602 has a first bore through which the first end of the preloader 405 is inserted. The second lever 602 is rotatably mounted over the first end of the preloader 405 . The second lever 602 has a second bore in its second end through which the second end of the preloader 603 is inserted. When rotation of the sprocket, gear, or pulley 38 ceases, the drive disk 34 continues to rotate forward and wind onto the screw 36 until it disengages from the speed adjusters 1 . The first end of the preloader 405 rotates forward causing the pinion pawl 409 to contact and rotate the pinion 403 clockwise. This causes the toothed wheel 402 to rotate counter-clockwise so that the toothed wheel pawl 411 passes over one or more teeth of the toothed wheel 402 , securing the drive disk 34 and preventing it from unwinding off of the screw 36 and contacting the speed adjusters 1 . When rotation of the sprocket, gear, or pulley 38 resumes, the second end of the preloader 603 rotates, contacting the second end of the second lever 602 causing the pinion pawl 409 to swing out and disengage from the pinion 403 , thereby allowing the drive disk 34 to unwind and reengage with the speed adjusters 1 . With this description in place, some of the particular improvements and advantages of the present invention will now be described. Note that not all of these improvements are necessarily found in all embodiments of the invention. Referring to FIG. 1 , a current improvement in some embodiments includes providing variable axial force to the drive disk 34 to respond to differing loads or uses. This can be accomplished by the use of multiple axial force generators. Axial force production can switch between a screw 35 and a nut 37 , with associated central drive shaft ramps 91 and screw ramps 90 , to perimeter ramps 61 , 64 . Or the screw 35 , central ramps 90 , 91 , and perimeter ramps 61 , 64 can share axial force production. Furthermore, axial force at the perimeter ramps 61 , 64 can be variable. This can be accomplished by the use of ramps of variable inclination and declination, including concave and convex ramps. Referring to FIG. 1 and FIGS. 6–8 and the previous detailed description, an embodiment is disclosed where affixed to the bearing disk 60 is a first set of perimeter ramps 61 , which may be concave, with which the ramp bearings 62 contact. Opposite the first set of perimeter ramps 61 are a second set of perimeter ramps 97 that are attached to the drive disk 34 , which may be convex, and which are in contact with the ramp bearings 62 . The use of concave and convex ramps to contact the ramp bearings 62 allows for non-linear increase or decrease in the axial load upon the drive disk 34 in response to adjustments in the position of the speed adjusters 1 and the support member 18 . Another improvement of certain embodiments includes positively engaging the bearing disk 60 and the drive disk 34 to provide greater rotational transmission and constant axial thrust at certain levels of torque transmission. Referring to an embodiment illustrated in FIG. 1 as described above, this may be accomplished, for example, by the use of the hook 114 and latch 115 combination where the hook 114 is attached to the bearing cage 63 that houses the ramp bearings 62 between the drive disk 34 and the bearing disk 60 , and the latch 115 is attached to the drive disk 34 that engages with the hook 114 when the ramp bearings 62 reach their respective limit positions on the ramp faces. Although such configuration is provided for example, it should be understood that the hook 114 and the latch 115 may be attached to the opposite component described above or that many other mechanisms may be employed to achieve such positive engagement of the bearing disk 60 and the drive disk 34 at limiting positions of the ramp bearings 62 . A further improvement of certain embodiments over previous designs is a drive disk 34 having radial spokes (not separately identified), reducing weight and aiding in assembly of the transmission 100 . In a certain embodiment, the drive disk 34 has three spokes equidistant from each other that allow access to, among other components, the hook 114 and the latch 115 . Another improvement of certain embodiments includes the use of threads 35 , such as acme threads, to move the drive disk 34 axially when there is relative rotational movement between the drive disk 34 and the bearing disk 60 . Referring to the embodiment illustrated in FIG. 1 , a threaded male screw 35 may be threaded into a set of female threads 37 , or a nut 37 , in the bore of the drive disk 34 . This allows the drive disk 34 to disengage from the speed adjusters 1 when the drive disk 34 ceases to provide input torque, such as when coasting or rolling in neutral, and also facilitates providing more or less axial force against the speed adjusters 1 . Furthermore, the threaded male screw 35 is also designed to transmit an axial force to the drive disk 34 via the set of female threads 37 . Yet another improvement of certain embodiments over past inventions consists of an improved method of shifting the transmission to higher or lower transmission ratios. Again, referring to the embodiment illustrated in FIG. 1 , this method can be accomplished by using a threaded rod 10 , including, for example, a left hand threaded worm screw 11 and a corresponding right hand threaded shifting tube 50 , or sleeve, that operates remotely by a cable 53 or remote motor or other remote means. Alternatively, left-handed threads can be used for both the worm screw 11 and the shifting tube, or a non-threaded shifting tube 50 could be used, and any combinations thereof can also be used as appropriate to affect the rate of shifting the transmission 100 with respect to the rate of rotation of the shifting tube 50 . Additionally, a conical spring 55 can be employed to assist the operator in maintaining the appropriate shifting tube 50 position. The worm screw 11 is preferably mated with a threaded sleeve 19 so as to axially align the support member 18 so that when the worm screw 11 is rotated the support member 18 will move axially. Another improvement of some embodiments over past inventions is the disengagement mechanism for the transmission 100 . The disengagement mechanism allows the input sprocket, pulley, or gear 38 to rotate in reverse, and also allows the transmission 100 to coast in neutral by disengaging the drive disk 34 from the speed adjusters 1 . The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention can be practiced in many ways. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the invention with which that terminology is associated. The scope of the invention should therefore be construed in accordance with the appended claims and any equivalents thereof.	A continuously variable transmission is disclosed for use in rotationally or linearly powered machines and vehicles. The transmission provides a simple manual shifting method for the user. Further, the practical commercialization of traction roller transmissions requires improvements in the reliability, ease of shifting, function and simplicity of the transmission. The present invention includes a continuously variable transmission that may be employed in connection with any type of machine that is in need of a transmission. For example, the transmission may be used in (i) a motorized vehicle such as an automobile, motorcycle, or watercraft, (ii) a non-motorized vehicle such as a bicycle, tricycle, scooter, exercise equipment or (iii) industrial equipment, such as a drill press, power generating equipment, or textile mill.	5

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