primitive words as space, time motion, equality, majority, diminution, whole, and others which every one understands. but apart from these, the rest of the terms that this science employs are to such a degree elucidated and defined that we have no need of a dictionary to understand any of them ; so that in a word all these terms are perfectly intelligible, either by natural enlightenment or by the definitions that it gives of them. this is the manner in which it avoids all the errors that may be encountered upon the first point, which consists in defining only the things that have need of it. it makes use of it in the same manner in respect to the other point, which consists in proving the propositions that are not evident. for, when it has arrived at the first known truths, it pauses there and asks whether they are admitted, having nothing clearer whereby to prove them ; so that all that is proposed by geometry is perfectly demonstrated, either by natural enlightenment or by proofs. it will perhaps be found strange that geometry does not define any of the things that it has for its principal objects ; for it can neither define motion, numbers, nor space ; and nevertheless these three things are those of which it treats in particular, and according to the investigation of which it takes the three different names of mechanics, arithmetic, and geometry, this last name belonging to the genus and species. but this will not surprise us if we remark that, this admirable science only attaching itself to the simplest things, this same quality which renders them worthy of being its objects renders them incapable of being defined ; so that the lack of definition is a perfection rather than a defect, since it does not come from their obscurity, but on the contrary from their extreme obviousness, which is such that though it may not have the conviction of demonstrations, it has all their certainty. it supposes therefore that we know what is the thing that is understood by the words motion, number, space ; and without stopping to define them to no purpose, it penetrates their nature and discovers their marvellous properties. these three things which comprehend the whole universe, according to the words : deus fecit omnia in pondere, in numero, et mensura, 4 have a reciprocal and necessary connection. for we cannot imagine motion without something that moves ; and this thing being one, this unity is the origin of all numbers ; and lastly, motion not being able to exist without space, we see these three


, 4 have a reciprocal and necessary connection. for we cannot imagine motion without something that moves ; and this thing being one, this unity is the origin of all numbers ; and lastly, motion not being able to exist without space, we see these three things included within the first. for however quick a movement may be, we can conceive of one still more so ; and so on ad infinitum, without ever reaching one that would be swift to such a degree that nothing more could be added to it. and, on the contrary, however slow a movement may be, it can be retarded still more ; and thus ad infinitum, without ever reaching such a degree of slowness that we could not thence descend into an infinite number of others, without falling into rest. in the same manner, however great a number may be, we can conceive of a greater ; and thus ad infinitum, without ever reaching one that can no longer be increased. and on the contrary, however small a number may be as, the hundredth or ten thousandth part, we can still conceive of a less ; and so on ad infinitum, without ever arriving at zero or nothingness. however a great space may be, we can conceive of a greater ; and thus ad infinitum, without ever arriving at one which can no longer be increased. and, on the contrary, however, small a space may be, we can still imagine a smaller ; and so on ad infinitum, without ever arriving at one indivisible, which has no longer any extent. that is, in a word, whatever movement, whatever number, whatever space, whatever time there may be, there is always a greater and a less than these : so that they all stand betwixt nothingness and the infinite, being always infinitely distant from these extremes. all these truths cannot be demonstrated ; and yet they are the foundations and principles of geometry. but as the cause that renders them incapable of demonstration is not their obscurity, but on the contrary their extreme obviousness, this lack of proof is not a defect, but rather a perfection. from which we see that geometry can neither define objects nor prove principles ; but for this single and advantageous reason that both are in an extreme natural clearness, which convinces reason more powerfully than discourse. for what is more evident than this truth, that a number, whatever it may be, can be increasedcan


; but for this single and advantageous reason that both are in an extreme natural clearness, which convinces reason more powerfully than discourse. for what is more evident than this truth, that a number, whatever it may be, can be increasedcan be doubled? again, may not the speed of a movement be doubled, and may not a space be doubled in the same manner? and who too can doubt that a number, whatever it may be, may not be divided into a half, and its half again into another half? for would this half be a nothingness? and would these two halves, which would be two zeros, compose a number? in the same manner, may not a movement, however slow it may be, be reduced in speed by a half, so that it will pass over the same space in double the time, and this last movement again? for would this be a perfect rest? and would these two halves of velocity, which would be two rests, compose again the first velocity? lastly, may not a space, however small it may be, be divided into two, and these halves again? and how could these two halves become indivisible without extent, which joined together made the former extent? there is no natural knowledge in mankind that precedes this, and surpasses it in clearness. nevertheless, in order that there may be examples for every thing, we find minds excellent in all things else, that are shocked by these infinities and can in no wise assent to them. i have never known any person who thought that a space could not be increased. but i have seen some, very capable in other respects, who affirmed that a space could be divided into two indivisible parts, however absurd the idea may seem. i have applied myself to investigating what could be the cause of this obscurity, and have found that it chiefly consisted in this, that they could not conceive of a continuity divisible ad infinitum, whence they concluded that it was not divisible. it is an infirmity natural to man to believe that he possesses truth directly ; and thence it comes that he is always disposed to deny every thing that is incomprehensible to him ; whilst in fact he knows naturally nothing but falsehood, and whilst he ought to receive as true only those things the contrary of which appear to him as false. and hence, whenever a proposition is inconceivable, it is necessary to suspend the judgment


fact he knows naturally nothing but falsehood, and whilst he ought to receive as true only those things the contrary of which appear to him as false. and hence, whenever a proposition is inconceivable, it is necessary to suspend the judgment on it and not to deny it from this indication, but to examine its opposite ; and if this is found to be manifestly false, we can boldly affirm the former, however incomprehensible it may be. let us apply this rule to our subject. there is no geometrician that does not believe space divisible ad infinitum. he can no more be such without this principle than man can exist without a soul. and nevertheless there is none who comprehends an infinite division ; and he only assures himself of this truth by this one, but certainly sufficient reason, that he perfectly comprehends that it is false that by dividing a space we can reach an indivisible part, that, is, one that has no extent. for what is there more absurd than to pretend that by continually dividing a space, we shall finally arrive at such a division that on dividing it into two, each of the halves shall remain indivisible and without any extent, and that thus these two negations of extensions will together compose an extent? for i would ask those who hold this idea, whether they conceive clearly two indivisibles being brought into contact ; if this is throughout, they are only the same thing, and consequently the two together are indivisible ; and if it is not throughout, it is then but in a part ; then they have parts, therefore they are not indivisible. if they confess, as in fact they admit when pressed, that their proposition is as inconceivable as the other, they acknowledge that it is not by our capacity for conceiving these things that we should judge of their truth, since these two contraries being both inconceivable, it is nevertheless necessarily certain that one of the two is true. but as to these chimerical difficulties, which have relation only to our weakness, they oppose this natural clearness and these solid truths : if it were true that space was composed of a certain finite number of indivisibles, it would follow that two spaces, each of which should be square, that is, equal and similar on every side, being the one the double of the other, the one would contain a number of these indivisi


better remedy than to make them look through glasses that magnify this delicate point to a prodigious mass ; whence they will easily conceive that by the aid of another glass still more artistically cut, they could be magnified so as to equal that firmament the extent of which they admire. and thus these objects appearing to them now easily divisible, let them remember that nature can do infinitely more than art. for, in fine, who has assured them that these glasses change the natural magnitude of these objects, instead of re - establishing, on the contrary, the true magnitude which the shape of our eye may change and contract like glasses that diminish? it suffices to say to minds clear on this matter that two negations of extension cannot make an extension. but as there are some who pretend to elude this light by this marvellous answer, that two negations of extension can as well make an extension as two units, neither of which it is a number, can make a number by their combination ; it is necessary to reply to them that they might in the same manner deny that twenty thousand men make an army, although no single one of them is an army ; that a thousand houses make a town, although no single one is a town ; or that the parts make the whole, although no single one is the whole ; or, to remain in the comparison of numbers, that two binaries make a quaternary, and ten tens a hundred, although no single one is such. but it is not to have an accurate mind to confound by such unequal comparisons the immutable nature of things with their arbitrary and voluntary names, names dependent upon the caprice of the men who invented them. for it is clear that to facilitate discourse the name of army has been given to twenty thousand men, that of town to several houses, that of ten to ten units ; and that from this liberty spring the names of unity, binary, quaternary, ten, hundred, different through our caprices, although these things may be in fact of the same kind by their unchangeable nature, and are all proportionate to each other and differ only in being greater or less, and although, as a result of these names, binary may not be a quaternary, nor the house a town, any more than the town is a house. but again, although a house is not a town, it is not however a negation of a town ; there


these names, binary may not be a quaternary, nor the house a town, any more than the town is a house. but again, although a house is not a town, it is not however a negation of a town ; there is a great difference between not being a thing, and being a negation of it. for, in order to understand the thing to the bottom, it is necessary to know that the only reason why unity is not in the ranks of numbers, is that euclid and the earliest authors who treated of arithmetic, having several properties to give that were applicable to all the numbers except unity, in order to avoid often repeating that in all numbers except unity this condition is found, have excluded unity from the signification of the word number, by the liberty which we have already said can be taken at will with definitions. thus, if they had wished, they could in the same manner have excluded the binary and ternary, and all else that it pleased them ; for we are master of these terms, provided we give notice of it ; as on the contrary we may place unity when we like in the rank of numbers, and fractions in the same manner. and, in fact, we are obliged to do it in general propositions, to avoid saying constantly, that in all numbers, as well as in unity and in fractions, such a property is found ; and it is in this indefinite sense that i have taken it in all that i have written on it. but the same euclid who has taken away from unity the name of number, which it was permissible for him to do, in order to make it understood nevertheless that it is not a negation, but is on the contrary of the same species, thus defines homogeneous magnitudes : magnitudes are said to be of the same kind, when one being multiplied several times may exceed the other ; and consequently, since unity can, be - ing multiplied several times, exceed any number whatsoever, it is precisely of the same kind with numbers through its essence and its immutable nature, in the meaning of the same euclid who would not have it called a number. it is not the same thing with an indivisible in respect to an extension. for it not only differs in name, which is voluntary, but it differs in kind, by the same definition ; since an indivisible, multiplied as many times as we like, is so far from being able to exceed an extension, that it can never


and then we shall find a perfect correspondence between these things ; for all these magnitudes are divisible ad infinitum, without ever falling into their indivisibles, so that they all hold a middle place between infinity and nothingness. such is the admirable relation that nature has established between these things, and the two marvellous infinities which she has proposed to mankind, not to comprehend, but to admire ; and to finish the consideration of this by a last remark, i will add that these two infinites, although infinitely different, are notwithstanding relative to each other, in such a manner that the knowledge of the one leads necessarily to the knowledge of the other. for in numbers, inasmuch as they can be continually augmented, it absolutely follows that they can be continually diminished, and this clearly ; for if a number can be multiplied to 100, 000, for example, 100, 000th part can also be taken from it, by dividing it by the same number by which it is multiplied ; and thus every term of augmentation will become a term of division, by changing the whole into a fraction. so that infinite augmentation also includes necessarily infinite division. and in space the same relation is seen between these two contrary infinites ; that is, that inasmuch as a space can be infinitely prolonged, it follows that it may be infinitely diminished, as appears in this example : if we look through a glass at a vessel that recedes continually in a straight line, it is evident that any point of the vessel observed will continually advance by a perpetual flow in proportion as the ship recedes. therefore if the course of the vessel is extended ad infinitum, this point will continually recede ; and yet it will never reach that point in which the horizontal ray carried from the eye to the glass shall fall, so that it will constantly approach it without ever reaching it, unceasingly dividing the space which will remain under this horizontal point without ever arriving at it. from which is seen the necessary conclusion that is drawn from the infinity of the extension of the course of the vessel to the infinite and infinitely minute division of this little space remaining beneath this horizontal point. those who will not be satisfied with these reasons, and will persist in the belief that space is not divisible ad infinitum, can make no pretensions to geometrical demonstrations, and although they may be enlightened in other things, they will be very little in this ; for one can easily be


belief that space is not divisible ad infinitum, can make no pretensions to geometrical demonstrations, and although they may be enlightened in other things, they will be very little in this ; for one can easily be a very capable man and a bad geometrician. but those who clearly perceive these truths will be able to admire the grandeur and power of nature in this double infinity that surrounds us on all sides, and to learn by this marvellous consideration to know themselves, in regarding themselves thus placed between infinitude and a negation of extension, between an infinitude and a negation of number, between an infinitude and a negation of movement, between an infinitude and a negation of time. from which we may learn to estimate ourselves at our true value, and to form reflections which will be worth more than all the rest of geometry itself. i have thought myself obliged to enter into this long discussion for the benefit of those who, not comprehending at first this double infinity, are capable of being persuaded of it. and although there may be many who have sufficient enlightenment to dispense with it, it may nevertheless happen that this discourse which will be necessary to the one will not be entirely useless to the other. note 1. after this paragraph occur in the ms. the following lines, written in a finer hand, and inclosed in parenthesis : is much more to succeed in the one than the other, and i have chosen this science to attain it only because it alone knows the true rules of reasoning, and, without stopping at the rules of syllogisms which are so natural that we cannot be ignorant of them, stops and establishes itself upon the true method of conducting reasoning in all things, which almost every one is ignorant of, and which it is so advantageous to know, that we see by experience that among equal minds and like circumstances, he who possesses geometry bears it away, and acquires a new vigor. i wish, therefore, to explain what demonstrations are by the example of those of geometry, which is almost the only one of the human sciences that produces infallible ones, because she alone observes the true method, whilst all the others are, through a natural necessity, in a sort of confusion, which the geometricians alone know exceedingly well how to comprehend. on the margin of this fragment is in the ms. the following note : that which is in small characters was hidden under a paper, the edges of which were glued,


of confusion, which the geometricians alone know exceedingly well how to comprehend. on the margin of this fragment is in the ms. the following note : that which is in small characters was hidden under a paper, the edges of which were glued, and upon which was written the article beginning : i cannot better explain, etc. faugere. [ back ] note 2. pascal alludes here to father noel, a jesuit, with whom he had had a warm discussion on the subject of his experiences touchant le vide. in a letter that he wrote to father noel in 1647, he said : the sentence which precedes your closing compliments defines light in these terms : light is a luminous motion of rays composed of lucid, that is, luminous bodies ; upon which, i have to tell you that it seems to me that you ought first to have defined what luminous is, and what a lucid or luminous body is, for till then, i cannot understand what light is. and as we never make use in definitions of the term of the thing defined, i should have difficulty in conforming to yours which says : light is a luminary motion of a luminous body. faugere. [ back ] note 3. here the ms. adds in parenthesis : ( but as nature punishes all that science does not bestow, its order in truth does not give a superhuman perfection, but it has all that man can attain. it has seemed to me proper to give from the beginning of this discourse this, etc. ). faugere. [ back ] note 4. god has made all things in weight, number and proportion. [ back ]


27 - 10 - 2008 : an international team of scientists has performed the ultimate miniaturisation of computer memory : storing information inside the nucleus of an atom. this breakthrough is a key step in bringing to life a quantum computer - a device based on the fundamental theory of quantum mechanics which could crack problems unsolvable by current technology. in the quantum world, objects such as atoms are allowed to exist in multiple states simultaneously - that is, they could literally be in two places at once or possess a number of other seemingly mutually exclusive properties. quantum computing is seen as the holy grail of computing because each individual piece of information, or ‘ bit ’, can have more than one value at once, as opposed to current technology which is limited to either 1s or 0s. this yields unprecedented processing power and thus dramatically widens the scope of what computers can do. the problem : how do you isolate a quantum bit from a noisy environment to protect the delicate quantum information, while at the same time allowing it to interact with the outside world so that it can be manipulated and measured? the team, with scientists and engineers from oxford and princeton universities and lawrence berkeley national laboratory, reported a solution to this problem in nature. the team ’ s plan was to devise a hybrid system using both the electron and nucleus of an atom of phosphorous embedded in a silicon crystal. each behaves as a tiny quantum magnet capable of storing quantum information, but inside the crystal the electron is more than a million times bigger than the nucleus, with a magnetic field that is a thousand times stronger. this makes the electron well - suited for manipulation and measurement, but not so good for storing information, which can become rapidly corrupted. this is where the nucleus comes in : when the information in the electron is ready for storage, it is moved into the nucleus where it can survive for much longer times. the experiments were made possible by the use of silicon enriched with the single 28si iso - tope, painstakingly grown by the berkeley team into large crystals while keeping the material ultra - pure and free from contaminants. “ the electron acts as a middle - man between the nucleus and the outside world. it gives us a way to have our cake and eat it - fast processing speeds from the electron, and long memory times from the nucleus, ” said john morton, a research fellow at st. john ’ s college, oxford and lead author of the letter to nature. crucially, the information stored in the nucleus had a lifetime of about 1 and


and long memory times from the nucleus, ” said john morton, a research fellow at st. john ’ s college, oxford and lead author of the letter to nature. crucially, the information stored in the nucleus had a lifetime of about 1 and 3 / 4 seconds, exceeding a recently calculated target for quantum computing in silicon beyond which known error correction techniques could then protect the data for an arbitrarily long period of time. without this technique the longest researchers had been able to preserve quantum information in silicon was a few tens of milliseconds. “ nobody really knew how long a nucleus might hold quantum information in this system. with the crystals from lawrence berkeley and very careful measurements we were delighted to see memory times exceeding the threshold, ” said steve lyon, leader of the princeton team. many different approaches to building a quantum computer are being studied, however one great advantage of the model used here is that it is based on silicon technology, which makes it more compatible with today ’ s computers. this is where you can add this news to your personal favourites for nature and chemists alike, making atmospheric nitrogen available for the formation of more complex nitrogen compounds is both essential and difficult. paul chirik and scott semproni at princeton university, usa, report the first examples of the use of group 4 metallocene complexes for b... more us and german scientists have used laser light to guide micro - particles through a solution towards a target. the technique could be applied to transport the particles to specific locations inside living cells, they say. these so - called ‘ micro - swimmers ’ consist of a polystyrene sphere with o... more the max planck society is strengthening its commitment to the development of a sustainable energy supply and has joined forces with internationally renowned princeton university to establish the max planck princeton research center for plasma physics. shirley m. tilghman, the president of p... more researchers with the u. s. department of energy ( doe ) ’ s lawrence berkeley national laboratory ( berkeley lab ) have once again demonstrated the incredible capabilities of metamaterials – artificial nanoconstructs whose optical properties arise from their physical structure rather than their ch... more exactly how a crystal forms from solution is a problem that has occupied scientists for decades. researchers at eindhoven university of technology ( tu / e ), together with researchers from germany and the usa, are now presenting the missing piece. this classical theory of crystal formation, wh... more the phenomenon in ferromagne


4 - wheeled motor vehicle. 6. a stock exchange in new york. 7. includes some plants usually placed in e. g. genus dicksonia. 8. any group or radical of the form rco - where r is an organic group. 9. ( informal ) being satisfactory or in satisfactory condition. 10. the seventh month of the moslem calendar. 11. a means of serving. 12. a unit that is part of some military service. 18. ( botany ) of or relating to the axil. 20. the branch of computer science that deal with writing computer programs that can solve problems creatively. 24. type genus of the cariamidae comprising only the crested cariama. 26. by bad luck. 27. the basic unit of electric current adopted under the system international d ' unites. 28. ( astronomy ) the angular distance of a celestial point measured westward along the celestial equator from the zenith crossing. 30. type genus of the family arcidae. 31. the battle in 1806 in which napoleon decisively defeated the prussians. 33. a fixed charge for a privilege or for professional services. 34. a constellation in the southern hemisphere near telescopium and norma. 35. any of numerous hairy - bodied insects including social and solitary species. 37. a bantu language spoken by the kamba people in kenya. 39. a burn cause by hot liquid or steam. 41. manufactured in standard sizes to be shipped and assembled elsewhere. 42. a city of southeastern mexico. 46. a light springing movement upwards or forwards. 47. a very poisonous metallic element that has three allotropic forms. 48. the basic unit of money in bangladesh. 49. very dark black. 50. a challenge to do something dangerous or foolhardy. 52. the rate at which heat is produced by an individual in a resting state. 53. top part of an apron. 54. a unit of conductance equal to the reciprocal of an ohm. 58. a hard gray lustrous metallic element that is highly corrosion - resistant. 59. the blood group whose red cells carry both the a and b antigens.


210 suppliers ) condensers are devices which accept a vapor stream and convert it to a liquid using heat transfer and / or compression. they are used in steam turbines for power plants, in cooling units for in - process fluids, and in air conditioning systems for buildings and automobiles. search by specification | learn more about condensers cooling towers ( 243 suppliers ) cooling towers are defined as any open water recirculation device that uses fans or natural draft to draw or force air to contact and cool water by evaporation. search by specification | learn more about cooling towers cooling tunnels ( 35 suppliers ) cooling tunnels ensure controlled temperature reduction in both batch and continuous process systems. they are similar to air convention ovens, but have no heating capacity. learn more about cooling tunnels crucibles ( 150 suppliers ) cryogenic equipment ( 141 suppliers ) cryogenic equipment produces or is used in the production of very low temperature materials or processes. learn more about cryogenic equipment cryostats and dewars ( 53 suppliers ) cryostats and dewars are used to keep sensors and store samples at very cold temperatures. learn more about cryostats and dewars dampers and louvers ( 264 suppliers ) dampers and louvers are used to control the flow of air in a process system or enclosed area. dampers are usually motorized or manually - adjustable for flow control. louvers are often fixed for a constant flow rate. learn more about dampers and louvers deaerators ( 61 suppliers ) deaerators are used to remove dissolved, corrosive gases from boiler feed water. they heat incoming makeup water for injection into the boiler, and return the condensate to a temperature which minimizes the solubility of these gases. learn more about deaerators dehumidifiers ( 181 suppliers ) desuperheaters ( 38 suppliers ) desuperheaters are used to cool steam in power plants. learn more about desuperheaters economizers ( 43 suppliers ) economizers are mechanical devices that are designed to reduce energy consumption, or to perform other useful, energy - related functions ( such as preheating fluids ). learn more about economizers evaporative coolers ( 138 suppliers ) evaporative coolers are cooling devices that use the evaporation of water into the air to cool the air temperature. they are sometimes called air coolers, desert coolers or swamp coolers. learn more about evaporative coolers fans and blowers ( industrial ) ( 1,


the pseudoscope creates one of the most remarkable of all optical illusions, and was first described by sir charles wheatstone in the 1830s. the pseudoscope swaps the incoming images, so that the right eye sees what the left eye would have seen, and vice versa. the pseudoscope therefore does to front and back what a mirror does to left and right. this means that foreground becomes background and visible background becomes foreground, or more simply, background advances, foreground recedes. when you view objects with this scope, the convex becomes concave. a tree turns inside out as it were - it ' s front branches appear at the back, whilst the back branches come out in front, hanging or suspended in mid - air as their support is eclipsed by branches in front. the scope will suggest to the viewer that a person ' s face is hollow or concave but your brain refuses to accept such nonsence and so peoples ' heads merely appear odd or uncomfortable to look at. it is best then to choose to look at a landscape or tree or anything which may suggest ambiguous perspective. in a real sense pseudoscopic vision fights ` normal vision '. it is, after all, a major alteration to the way information is being presented to the brain for processing, and some people, not all, find there is initially at least, a tendency to suppress the extraordinary interpretation of space it reveals. because of this unfamiliarity, the full pseudoscopic experience might take a little time to assert itself. some people find that they can never see a pseudoscopic image. these pseudoscopes come as a kit form, and require assembly. this is a fairly complex kit, and it will take a number of hours to complete. there are a total of four mirrors. there are two front silvered glass mirrors ( the two small mirrors ) and two acrylic mirrors ( the large ones ) included in the kit. you will need to provide glue. the kit comes from germany, but we provide an english translation of the instructions. experience space on the flipside! suggested age 16 + made in eu


abrasion / sanding the wearing away of any part of material by rubbing it against another surface. the term is often used to describe the processes of creating an aged look in denim. abrasion can be achieved through hand rubbing with sandpaper or even washing garments with stones or rubber balls to break down the surface of the fabric. think of the abraded seams and hems on your favorite pair of old jeans. this is the distressed look ( as opposed to worn - out ) that is entirely intentional. agate a semiprecious type of quartz also known as chalcedony ( pronounced kal - sed - nee ). it forms in a wide variety of colors and textures. each individual agate forms by filling a cavity in a host rock. agate was highly valued as a talisman or amulet in ancient times. it was said to quench thirst or protect from fevers. persian magicians used agate to divert storms. amazonite : a semiprecious gemstone that is a variety of green microcline feldspar. it varies in color from apple green to bluish green. also known as amazon stone, it is commonly found in the united states, brazil, zimbabwe, russia, australia and namibia. it is said to enhance clarity and understanding while balancing human energies. antique fleece a mellow blend of cotton and polyester. washed for a soft, lived - in quality. fleece lining lends a warm, cozy feel. applique ( pronounced a - plee - kay ) : material that is cut out and sewn or embroidered and fastened to a fabric. applique comes from the french appliquer, which means to " put on. " the art of hand applique covers a wide spectrum, from primitive folk art to the sophistication of baltimore album quilts — elegant appliqued quilts from the mid - 1800s that were highly sought - after and considered an honor to receive. authentic fit our stretch boot - cut style with a vintage appeal. it sits below the waistline and follows the contours of hips and thighs with its slightly fitted approach. whiskering detail adds to the " lived - in " appeal. aventurine ( sometimes known as goldstone ) a shimmering quartz ( crystalline mineral ) stone that ranges in color from yellow and red to light green and light brown. the shimmer is caused by tiny metallic particles ( mica ) within the stone. the mineral aventurine takes its


by yan zhang - princeton university the 2008 olympic games in beijing have focused attention on the problems of air quality in urban environments and will serve as an important platform for developing and testing new technologies and procedures for analysis and management of air quality problems. regional decisions concerning industrial development, agricultural practice and urban policy can play important roles in air quality problems linked to fine particulate matter. the olympic games will provide an important research venue for addressing these issues and unique opportunities for advancing novel environmental sensor systems and atmospheric models. in our work, we will deploy two environmental sensor systems at the institute of atmospheric physics, chinese academy of sciences near the olympic stadium in beijing from june to august 2008 for continuous monitoring of trace gases, before, during, and after the olympic games. data from these sensors will be incorporated into analyses using the weather research and forecasting model, a state - of - the - art meteorological model which is coupled with an atmospheric chemistry ( wrf - chem ) module. these analyses will be used to examine air quality problems in the beijing metropolitan region and regional climatology problems linked to trends of decreasing precipitation in the beijing metropolitan region associated with increased aerosol loadings. the environmental sensor systems deployed in beijing use quantum cascade lasers ( qcls ) as the core technology for measuring trace gases from " remote sensing " and " point " sensors. qcls are tiny, tunable mid - infrared ( mid - ir ) semiconductor laser sources that have extremely broad wavelength coverage ( 3 - 20 μm ), which includes the wavelength range where trace gases have their strongest absorption features. the lasers are designed to emit at aparticular wavelength ; thus, by knowing where a gas absorbs best, a laser can be designed for detection of that specific gas. as a result of new developments of qcls, laser absorption spectroscopy is becoming aviable alternative to other analytical methods for trace gas sensing. qclops ( quantum cascade laser open path system ) is an " open path " remote sensing system that uses two qcls for monitoring multiple trace gases. the principal target gases for qclops are ozone, ammonia, and carbon dioxide. elevated ozone levels in urban regions around the world present one of the greatest air quality and public health challenges associated with industrial and automobile emissions. ammonia plays an important and complex role in aerosol chemistry in urban environments and development of sensor systems for ammonia has proven especially challenging. carbon dioxide is broadly recognized as an important greenhouse gas and its measurement in urban environments is an important goal of qclops. the laser radiation is transmitted through the air and reflected


in urban environments and development of sensor systems for ammonia has proven especially challenging. carbon dioxide is broadly recognized as an important greenhouse gas and its measurement in urban environments is an important goal of qclops. the laser radiation is transmitted through the air and reflected back by a retro - reflector to a detector. the detector is connected to a data acquisition system and a computer. the computer runs a custom algorithm to calculate concentrations. no and no2 are important ozone precursors and their presence in urban environments is strongly connected to automobile emissions. detection of no and no2 is of great interest for air quality problems linked to elevated ozone concentrations. fast and sensitive detection of no can be realized by faraday rotation spectroscopy. the best no detection limit ( sub - ppbv ; parts per billion by volume ) can be obtained at approximately 5. 3 μm. an " externalcavity " ( ec ) qcl source that precisely coincides withth isoptimum absorption wavelength was developed and a faraday rotation spectrometer based on the ec - qcl was developed for detection of no. the measurement technique will allow for sensitive and selective measurements of no even in the presence of strongly interfering gases ( especially water vapor ). a fully automaticand autonomous ec - qcl faraday rotation spectroscopic sensorsystem will be deployed at the beijing test site for contiuous atnospheric no monitoring. the weather research and forecasting model, coupled with the wrf - chem atmospheric chemistry module ( wrf - chem ), provides a powerful platform for meteorological and air quality forecasting, as well as regional analyses of the impact of anthropogenic emissions on air quality and regional climate. wrf - chem has been used at princeton for analyses of aerosol impacts on regional precipitation climatology in the baltimore and new york city metropolitan region. with the collaboration of the nansen - zhu international center of the institute of atmospheric physics ( iap ), the chinese academy of sciences, wrf - chem will be implemented as a forecasting tool for the beijing olympics. an important element of the forecasting system will be integrating observations from sensor systems like qclops in to the forecasting process. the princeton group will also work closely with iap in studying and understanding how the urban aerosols influence local weather and public health through coupled modeling and monitoring analyses.


academic standards correlations on teachers ' domain use the achievement standards network ( asn ) database of state and national standards, provided to nsdl projects courtesy of jes & co. we assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. if a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by asn or by teachers ' domain. we will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment. air is a mixture of different molecules. its composition is the result of chemical reactions, atmospheric motion, and emissions from a variety of sources, both natural and manmade. one of these emissions is carbon dioxide ( co2 ). co2 is a greenhouse gas : it traps the heat from sunlight close to earth ' s surface. in their natural balance, greenhouse gases make earth habitable for humans and other living things. however, a change in their concentration may affect atmospheric temperatures dramatically. in fact, most climate scientists are convinced that an increased concentration of co2 in the atmosphere is one of the leading drivers of global warming today. in this lesson, students will discover how carbon dioxide is added into the atmosphere and the effect it ' s having on environmental public health. the lesson begins with a brief review of the molecules that make up air. students use lego bricks to model these molecules, with individual bricks representing the atoms that make up the molecules. continuing with lego bricks, they investigate how co2 enters the atmosphere through a chemical reaction called combustion. next, students learn about the relationship between air and atmospheric conditions, and watch a video that describes environmental disasters associated with atmospheric warming. they learn how the concentration of co2 in the atmosphere correlates with temperature and then explore an interactive activity that details the potential impact of atmospheric warming on human health. the lesson ends with a class discussion of ways to reduce the concentration of co2 in the air. note : this lesson may be followed up with the understanding air : air pollution and modeling pollutants with lego® bricks lesson plan, which demonstrates other forms of pollution that result from incomplete combustion and other chemical reactions in the air. climate change and human health interactive printing instructions : set scaling to " 0 % " or " none " so that the lego bricks on the printouts are actual size. print two - page documents back - to - back and laminate, if possible ; or


change and human health interactive printing instructions : set scaling to " 0 % " or " none " so that the lego bricks on the printouts are actual size. print two - page documents back - to - back and laminate, if possible ; or print one - sided and use a plastic sleeve. 1. explain that air is a mixture of gases and is essential to life. even though air is invisible, it is all around us. air is made up of molecules ( groups of two or more atoms that are bonded together ). the types and amounts of atoms and molecules in air can impact both environmental and public health. 2. to pique student interest, and to uncover any misconceptions students may have about air, conduct a class survey. hand out the what is air made of? guess! document survey, have students look at it, and then have them vote anonymously by raising their hands with their heads down and eyes closed. before revealing the correct answer ( b ), tally their votes and put them up on the board. note : the answer to the survey question is printed on the back of the handout, so tell students not to turn it over. if time allows, have students debate the question, then vote to see whose answer was most convincing. or, ask students to discuss what they know about air that might help them answer the question. you may reveal the correct answer to the class or allow them to discover it for themselves in the next step. 3. tell students they will now have a chance to make a model of air. distribute one lego® atoms and molecules layout mat document to each group of two or three students. this document explains the contents of the lego brick set. you may also distribute the lego® atoms and molecules : chemical reactions student worksheet document to refresh the students ' understanding of the types of matter. explain that they will use the lego bricks to model tiny particles of matter that are too small to be seen. each brick represents an atom, and they will use these atoms to build four types of molecules : nitrogen, oxygen, carbon dioxide, and water. using the back of the what is air made of? guess! document as their guide, have them construct a model of air that reflects the correct components and their concentrations. after they have done this, point out the " 390 parts per million ( ppm ) " label under the co2 molecule. have students convert 20 percent oxygen and 80 percent nitrogen into ppm. ( that is, convert the fractions 20 /


understanding microelectronics : a top - down approach december 2011, ©2011, wiley - blackwell this price is valid for united states. change location to view local pricing and availability. for today ’ s students, the most beneficial approach to learning is this top - down method that demonstrates a global view of electronics before going into specifics. franco maloberti uses this approach to explain the fundamentals of electronics, such as processing functions, signals and their properties. here he presents a helpful balance of theory, examples, and verification of results, while keeping mathematics and signal processing theory to a minimum. presents a new learning approach that will greatly improve students ’ ability to retain key concepts in electronics studies match the evolution of computer aided design ( cad ) which focuses increasingly on high - level design covers sub - functions as well as basic circuits and basic components provides real - world examples to inspire a thorough understanding of global issues, before going into the detail of components and devices discusses power conversion and management ; an important area that is missing in other books on the subject end - of - chapter problems and self - training sections support the reader in exploring systems and understanding them at increasing levels of complexity a supporting website ( http : / / www. wiley. com / wileycda / wileytitle / productcd - 047074555x, desccd - relatedwebsites. html ) presents the interactive student lab, elvislab, where students can conduct virtual experiments on circuits together with powerpoint slides for lecturers. inside this book you will find a complete explanation of electronics that can be applied across a range of disciplines including electrical engineering and physics. this comprehensive introduction will be of benefit to students studying electronics, as well as their lecturers and professors. postgraduate engineers, those in vocational training, and design and application engineers will also find this book useful.


microcalorimetry of macromolecules : the physical basis of biological structures this price is valid for united states. change location to view local pricing and availability. other available formats : e - book examining the physical basis of the structure of macromoleculesproteins, nucleic acids, and their complexesusing calorimetric techniques many scientists working in biology are unfamiliar with the basics of thermodynamics and its role in determining molecular structures. yet measuring the heat of structural change a molecule undergoes under various conditions yields information on the energies involved and, thus, on the physical bases of the considered structures. microcalorimetry of macromolecules offers protein scientists unique access to this important information. divided into thirteen chapters, the book introduces readers to the basics of thermodynamics as it applies to calorimetry, the evolution of the calorimetric technique, as well as how calorimetric techniques are used in the thermodynamic studies of macromolecules, detailing instruments for measuring the heat effects of various processes. also provided is general information on the structure of biological macromolecules, proteins, and nucleic acids, focusing on the key thermodynamic problems relating to their structure. the book covers : - the use of supersensitive calorimetric instruments, including micro and nano - calorimeters for measuring the heat of isothermal reactions ( isothermal titration nano - calorimeter ), the heat capacities over a broad temperature range ( scanning nano - calorimeter ), and pressure effects ( pressure perturbation nano - calorimeter ) - two of the simplest but key structural elements : the α and polyproline helices and their complexes, the α - helical coiled - coil, and the pyroline coiled - coils - complicated macromolecular formations, including small globular proteins, multidomain proteins and their complexes, and nucleic acids - numerous examples of measuring the ground state of protein energetics, as well as changes seen when proteins interact the book also reveals how intertwined structure and thermodynamics are in terms of a macromolecule ' s organization, mechanism of formation, the stabilization of its three - dimensional structure, and ultimately, its function. the first book to describe microcalorimetric technique in detail, enough for graduate students and research scientists to successfully plumb the structural mysteries of proteins and the double helix, microcalorimetry of macromolecule


quicksand and other non - newtonian fluids share properties with both liquids and solids. non - newtonian fluids consist of tiny grains suspended in liquid, with the appearance of a solid or gel. stand on quicksand and you will sink ( though not as rapidly as movies and cartoons suggest ). but strike it quickly and it will briefly harden. previous explanations of quicksand behavior relied on the presence of containment walls and effects like grain dilation under stress. however, a new experimental study challenges prior assumptions, showing that new concepts may be needed to explain non - newtonian fluids. scott r. waitukaitis and heinrich m. jaeger at the university of chicago created a quicksand - like substance called " oobleck " out of cornflour and water, which they then struck with an aluminum rod. by measuring the position, speed, and acceleration of the rod as it interacted with the oobleck, they determined that its solidification arises from compression that propagates away from the impact point. by using a huge amount of fluid ( 25 liters ), the researchers showed the bizarre non - newtonian effects were independent of the size of the container, so the presence of confining walls is irrelevant. through x - ray imaging, they discovered a nearly cylindrical solid region forms directly below the impact point. the detailed analysis led the authors to develop a simple model for the impact, which bears striking similarity to models for objects falling into liquids, but produces very different effects. this may have been the most carefully monitored bowl of starch ever devised. in the experiment, the researchers mounted the aluminum rod using guide rails to make sure it impacted along a single axis. for different trials, they either dropped the rod ( free fall ) or used a slingshot to drive it more quickly downward. the rod was fixed with an accelerometer, and the whole process was recorded on high - speed video to measure the instantaneous position, speed, and acceleration. the grains of the cornflour in the oobleck are irregularly shaped and range in size from 5 to 20 microns ( 0. 005 to 0. 02 millimeters ), which is typical of quicksand and other non - newtonian fluids. additionally, the suspension contained tracer particles that could be imaged with x - rays ; motion within the oobleck could be tracked with the tracers. the authors positioned a force sensor directly below the rod at the bottom of the container to examine how the impact


| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. | | an extraordinary or unusual thing, person, or event ; an exceptional example or instance. | | weber ( german ˈveːbər ) | | 1. | | baron carl maria friedrich ernst von ( karl maˈriːa ˈfriːdrɪc ɛrnst fɔn ). 1786 - - 1826, german composer and conductor. his three romantic operas are der freischutz ( 1821 ), euryanthe ( 1823 ), and oberon ( 1826 ) | | 2. | | ernst heinrich ( ɛrnst ˈhainrɪc ). 1795 - - 1878, german physiologist and anatomist. he introduced the psychological concept of the just noticeable difference between stimuli | | 3. | | max ( maks ). 1864 - - 1920, german economist and sociologist, best known for the protestant ethic and the spirit of capitalism ( 1904 - - 05 ) | | 4. | | wilhelm eduard ( ˈvɪlhɛlm ˈeːduart ). 1804 - - 91, german physicist, who conducted research into electricity and magnetism | weber web · er ( web ' ər, va ' bər ) a unit of magnetic flux in the international system of units equal to the product of one tesla and one square meter. weber we · ber ( va ' bər ), ernst heinrich. 1795 - 1878. german physiologist and psychologist who studied sensory response and is considered a founder of experimental psychology. | weber ( web ' ər, va ' bər ) pronunciation key the si derived unit of magnetic flux. a magnetic flux of one weber, passing through a conducting loop and reduced to zero at a uniform rate in one second, induces an electric potential of one volt in the loop. one weber is equal to one volt per second, or 108 maxwells. the weber is named after german scientist wilhelm eduard weber ( 1804 - 1891 ). | weber ( va ' bər ) pronunciation key german physiologist who is noted for his study of sensory response, particularly in the ear and the skin. he also demonstrated that the digestive juices are the specific products of glands.


to save one ' s self or property from harm or less. [ colloq. ] ba * co " ni * an (? ), a. of or pertaining to lord bacon, or to his system of philosophy. baconian method, the inductive method. see induction. bac * te " ri * a (? ), n. p. see bacterium. bac * te " ri * al (? ), a. ( biol. ) of or pertaining to bacteria. bac * te " ri * ci ` dal (? ), a. destructive of bacteria. bac * te " ri * cide (? ), n. [ bacterium + l. caedere to kill ] ( biol. ) same as germicide. bac * te " ri * o * log ` ic * al (? ), a. of or pertaining to bacteriology ; as, bacteriological studies. bac * te " ri * ol ` o * gist, n. one skilled in bacteriology. bac * te " ri * ol ` o * gy (? ), n. [ bacterium + - logy. ] ( biol. ) the science relating to bacteria. bac * te ` ri * o * scop " ic (? ), a. ( biol. ) relating to bacterioscopy ; as, a bacterioscopic examination. bac * te ` ri * os " co * pist (? ), n. ( biol. ) one skilled in bacterioscopic examinations. bac * te ` ri * os " co * py (? ), n. [ bacterium + - scopy ] ( biol. ) the application of a knowledge of bacteria for their detection and identification, as in the examination of polluted water. bac * te " ri * um (? ), n. ; pl. bacteria ( # ). [ nl., fr. gr.,, a staff : cf. f. bacterie. ] ( biol. ) a microscopic vegetable organism, belonging to the class algæ, usually in the form of a jointed rodlike filament, and found in putrefying organic infusions. bacteria are destitute of chlorophyll, and are the smallest of microscopic organisms. they are very widely diffused in nature, and multiply with marvelous rapidity, both by fission


chaos, like next year ’ s weather, is anything but predictable. so results appearing in the 8 october print issue of prl may seem paradoxical : researchers claim that for the first time, two lasers have been synchronized so that one can anticipate the chaotic fluctuations in the other. some experts are skeptical of the result, but it illustrates some of the challenges in the field of chaos research, where physicists are attempting to understand and make use of nature ’ s seeming disorder. the weather is a classic example of chaos. in a perfect world, a computer – given a complete set of atmospheric data and equations – should be able to crunch out forecasts for years to come. but in practice, tiny uncertainties in the initial data set eventually lead to completely inaccurate predictions. a laser also becomes very unpredictable if you reflect a small portion of the laser ’ s output back into the device. this feedback makes the laser ’ s future output – like next year ’ s weather – strongly dependent on its past. alan shore and his colleagues at the university of wales in bangor, uk, created fluctuations in their first laser – the “ transmitter ” – using this standard feedback technique. they also fed some of the transmitter ’ s light into a second, “ receiver ” laser, which went into fits of intensity fluctuations nearly identical with those of the transmitter. the team arranged the mirrors in a way that gave the transmitter ’ s feedback signal a long round trip, so the receiver got the signal earlier and anticipated the transmitter ’ s fluctuations by a fixed amount of time. surprisingly, that fixed anticipation time did not depend upon the round - trip time for light to re - enter the transmitter. several researchers have pointed out that even the tiniest amount of accidental light traveling from the receiver back to the transmitter could induce unintended fluctuations in the transmitter. they suggest that the receiver might not be anticipating fluctuations in the transmitter, but rather, causing them. shore says that there is a small amount of feedback from the receiver to the transmitter, but that his team has shown that this feedback is not causing the fluctuations in the transmitter – a result they will soon publish. although many experts want to consider this result more carefully, they are optimistic about the potential usefulness of chaos synchronization. dan gauthier of duke university in durham, nc, suggests one possible application for anticipating chaos : researchers could maintain an extremely steady laser intensity by using the advanced signal to counter fluctuations quickly. ingo fischer, of the university of darmstadt in germany, still sees open questions in the interpretation


stewart, ian. taming the infinite : the story of mathematics from the first numbers to chaos theory. quercus, dist. by trafalgar square. dec. 2011. 384p. illus. index. isbn 9781847247681. pap. $ 14. 95. math have you ever thought of math as terrific fun? stewart ( mathematics, univ. of warwick, uk ; why beauty is truth : the history of symmetry ) makes it that and more. his engaging writing style draws readers into the story of mathematics, giving it an arc and its players charismatic personalities, even when those players are notation systems. in each chapter, stewart chronologically examines a particular area of mathematics. he gives accessible, real - world examples that are easy to visualize and often illustrate the impact of complicated mathematical concepts on our daily lives. from tally marks and numerals, to euclid and pythagoras, to imaginary numbers and chaos theory, to godel and faraday, stewart offers an insightful and clear history of mathematical developments. the diagrams and illustrations are comprehensible for lay readers yet not condescendingly simple. throughout, stewart examines the discoveries of great mathematicians and offers absorbing anecdotes about their lives in special callouts throughout the book. verdict clear and readable, this is an essential title for math, science, and technology buffs and will be intriguing for all. it might even be of interest to teens! highly recommended. ‚ candice kail, columbia univ. libs., new york mount, ian. the vineyard at the end of the world : maverick winemakers and the rebirth of malbec. norton. jan. 2012. c. 288p. illus. bibliog. index. isbn 9780393080193. $ 26. 95. beverages adding to the growing body of work on wine history, wine journalist mount traces the history of argentinian wine from its beginning in the 1700s to the present day. to accomplish this monumental task in a digestible narrative, he focuses on one figure and one region but explains in the epilog that many other people and areas were also important. the result is an artfully written story of how a poorly developed wine culture grew into one of the best wine regions in the world. mount brings to light a lesser - known wine region and explains how cultural contact beginning with spanish explorers contributed to its current wine - producing status. the work is obviously well


one of the outstanding achievements of 20th century science was the realisation that the great diversity of nature is based on a handful of elementary particles acting under the influence of only a few fundamental forces. this talk aims to give an overview of the natural forces that shape everything around us and outlines current research and what we believe remains to be discovered. prof. peter kalmus is emeritus professor at queen mary, university of london. at various times he has been president of the physics section of the british association, vice president of the institute of physics, and vice president of the royal institution. a distinguished career has seen him awarded the rutherford medal for his outstanding role in the discovery of the w and z particles, an obe for his contributions to physics and only last week the kelvin medal for his role in the public understanding of physics. dramatic advances in the study of stem cells - the precursor cells of blood, skin, bone and nerve cells - could be used one day to help sufferers from parkinson ' s disease, hepatitis, leukaemia, diabetes and rheumatoid arthritis. stem cells hold the key to the ability to grow a patient ' s own tissue for repair, and are central to the cloning debate. potentially they could be used to create unlimited supplies of replacement tissue, including nerve, bone, skin and heart muscle, for repairing injuries and for treating disease - potentially saving millions of lives. cloning offers a way to grow a patient ' s own stem cells but, by perfecting such technology, scientists could accelerate efforts to conduct so - called reproductive cloning. professor richard gardner, who is chairing the royal society ' s working group on stem cells and therapeutic cloning provides a rich overview into the how and why of cloning. professor wolpert ' s thesis is that science is not common sense. common sense is misleading - it can make you accept that a seashell on the top of a mountain is proof of a global flood. in this talk professor wolpert gives one scientist ' s view of the culture of science and why the public ' s understanding of that culture is so much in error. his thoughtful analysis concludes that scientific thought is unnatural. as well as a cbe, professor wolpert is a fellow of the royal society and former chairman of the committee for the public understanding of science. in may he was awarded the royal institution ' s michael faraday award for services to the public understanding of science. the common flu of 1918 spread faster than any disease in history, before orsince, and killed more people


public understanding of science. in may he was awarded the royal institution ' s michael faraday award for services to the public understanding of science. the common flu of 1918 spread faster than any disease in history, before orsince, and killed more people in less time than all of the great plagues ofhistory, doing so in the presence of relatively ' modern ' medical science. even last year, approximately 20, 000 people in the uk died from what werethought to be flu - related illnesses. yet even this was not an epidemic - the spanish flu pandemic at the close of the first world war is believed tohave accounted for the deaths of well over 20m people worldwide, including280, 000 in the uk. the last official flu epidemic was 11 years ago, butthe fact that there is no way of guessing when the next one might be is avery serious concern. dr elspeth garman will go through at what we know ofthe different strains of flu virus and outline the progress made in thedevelopment of a cure. ref : ` the origin and control of flu pandemics ' laver and garman, science sep 7, 2001, 1776 - 1777. cryptography, the science of encrypting and decrypting information, dates as far back as 1900 bc when a scribe in egypt first used a derivation of the standard hieroglyphics of the day to communicate today cryptography provides the locks and keys to the information age. it is the technology that enables private emails to be sent and secure business transactions to take place over the internet. simon singh, author of fermat ' s last theorem and the code book, will give a brief history of cryptography and then discuss its impact in the 21st century. he will also bring with him a genuine enigma cipher machine. simon singh completed his phd in particle physics at cambridge. in 1991 he joined the bbc science department and worked as a producer and director with ' tomorrow ' s world ' and ' horizon '. he is also the author of ' fermat ' s last theorem ' and ' the code book ', the latter forming the basis for the popular channel 4 series ' the science of secrecy '. this talk is run in conjunction with blackwellscafe scientifique.


we are remembered by our exaggerations. so at a recent reunion of my former research - group members, several recalled my saying " when you see a standard deviation in an x - ray crystal structure, multiply it by pi [ π, 3. 141... ], or if the structure is done by friends, by e [ 2. 718... ]. " i was talking about structures of molecules — details of their geometry, also of a particularly fruitful way to gain knowledge of these structures. and of the error estimates in such studies. there is no more basic enterprise in chemistry than the determination of the geometrical structure of a molecule. such a determination, when it is well done, ends speculation and provides us with the starting point for understanding every physical, chemical and biological property of the molecule. indeed, the chemical sciences ( only modestly imperialistic, i take them to range from materials science through molecular biology ) are what they are today largely as the result of careful structure determination. we ' d be still waiting in ignorance if we believed the hype of various microscopies. a few very accurate structures have come to us through ingenious use of electron diffraction and various spectroscopies. but the vast majority of what we know about shapes and metric detail of molecules and extended materials derives from studies of the diffraction of x rays by single crystals of molecules, a technique popularly called " x - ray crystallography. " » post comment


to use all functions of this page, please activate cookies in your browser. with an accout for my. chemeurope. com you can always see everything at a glance – and you can configure your own website and individual newsletter. - my watch list - my saved searches - my saved topics - my newsletter syenites are usually peralkaline and peraluminous, with high proportions of alakali elements and aluminium. syenites are formed from alkaline igneous activity, generally formed in thick continental crustal areas, or in cordilleran subduction zones. to produce a syenite, it is necessary to melt a granitic or igneous protolith to a fairly low degree of partial melting. this is required because potassium is an incompatible element and tends to enter a melt first, whereas higher degrees of partial melting will liberate more calcium and sodium, which produce plagioclase, and hence a granite, adamellite or tonalite. syenite is not a common rock, some of the more important occurrences being in new england, arkansas, montana, new york ( syenite gneisses ), switzerland, germany, and norway. the term syenite was originally applied to hornblende granite like that of syene in egypt, from which the name is derived. episyenite ( or epi - syenite ) is a term used in petrology to describe to the result of alteration of a sio2 rich rock to a more sio2 depleted rock. the term stems from " epi " and syenite. the process which results in sio2 depletion can be termed episyenitization. this process is only referring to the macroscopic result of relative sio2 depletion in a rock. the actual physical process leading to this sio2 depletion may vary in a given metamorphic environment. diffusion of chemical components in a stagnant fluid, related to differences in chemical potential or pressure as well as advection of a sio2 - undersaturated fluid may lead to the dissolution of quartz from the un - altered rock, thus depleting it of this component. | this article is licensed under the gnu free documentation license. it uses material from the wikipedia article " syenite ". a list of authors is available in wikipedia. |


activity 19. 1. 3 – discovering family similarities dimitri mendeleev, a russian chemist, created the first version of the periodic table of the elements ( figure 19. 3 ) in 1869. when he ordered the elements according to increasing atomic weight in columns so that rows contained analogous elements, he saw patterns that allowed him to predict the properties of elements yet to be discovered. mendeleev ’ s task was formidable because there was relatively little data to work with, and no electronic tools to organize it. today, however, we have an abundance of information as well as database tools that allow us to instantly group data by common characteristics. database technology has fueled the information revolution by allowing us to store and examine large amounts of data. in this activity you will use a database program to separate data by groups and summarize your findings. table 19. 2 ( see book ) arranges the elements in terms of increasing atomic number. no patterns or trends are seen when the elements are displayed in this fashion. if, however, elements are arranged as seen in the periodic table, those with similar properties are grouped together. each column represents a family of elements that have similar electron configuration and similar chemical properties. although the periodic table makes it easy to see which elements have similar properties ( those in the same family or column ), it does not allow for an easy comparison of these properties. by contrast, table 19. 2 lists much specific information about the properties of the elements, but does not allow for comparison of family ( group ) data, unless first arranged by group. sort the elements by group, then calculate average group values for heat of fusion, specific heat, thermal conductivity, and other properties of your choice using the subtotal command and average option. list your results. database. ( 1 ) which families are most similar to each other? ( 2 ) which families are most dissimilar to each other?


and so controllable, safe, clean, and irresistible is hydrostatic pressure, either of air or water, that, now our mechanical skill in construction is sufficiently advanced, it must come more and more into use. we might almost anticipate from its wide adoption a perfect utopian system of machine labour, in which human labour would be restricted to the simple direction of the hydraulic pressure. but before indulging in imaginary approximations to perfection, it is well to inquire into the several conditions of possibility. to the capabilities of hydrostatic pressure there is perhaps physically speaking scarcely a limit, but commercially speaking our command of water power, or hydrostatic power, in whatever form, is nearly limited to our command of steam. it is steam that presents us with hydrostatic power in its most abundant and available form. water power in uniform abundance is to be had, in this country at least, only through steam ; and all experience points to the fact that, instead of water being a possible commercial substitute for steam, it is steam that from its first use has been a substitute for water power. a brief consideration of the history of the steam - engine will put this fact in the clearest light. though water power had been in use since the time of the romans, a great want was clearly felt in the seventeenth century of some new power, antithetical to water power, so to speak, and capable of overcoming it, so that drowned mines might be pumped dry, and water might be raised to furnish artificial water power, where a natural supply was not to be had. the earliest explicit patent for a new engine was directed to the raising of water, * 25 and the " exact and true definition " of the marquis of worcester ' s engine clearly expressed a similar purpose. " there being indeed no place but either wanteth water, or is overburdened therewith... by this engine either defect is remediable. " hence the marquis calls his invention a " stupendous water commanding engine, " and truly regarded it as a new primum mobile which was to overcome the force of falling water. his appreciation of the value of water power is shown by his remarkable motto : * 26 — " whosoever is master of weight is master of force, " and consequently, " said he, " to him all forcible actions and achievements are easy, which are in any wise beneficial to, or for, mankind. " savery had no less correct and exalted notions of what his engine


become a fan of h2g2 the word ' phlogiston ' 1 is derived from the greek language. it is the neuter form of the word phlogistos, meaning ' inflammable '. this word is in turn derived from phlogizein meaning ' to set on fire ', derived from phlox, or phlog -, meaning flame. burning, as can be seen, is at the root of this area of scientific thought. the theory of phlogiston arose in the late 17th century when it was proposed by johann becher ( who referred to it as ' inflammable earth ' ). it was continued in the work of georg stahl. the theory postulates that in all flammable materials the elusive substance phlogiston is present, a substance without colour, odour, taste or weight, which is given off when materials are burnt. all materials could have three basic parts : phlogiston, impurities and the purest form of the material. anything that could be burned to nothing would be considered to have been completely composed of phlogiston - such as charcoal or sulphur. so, for example, wood when burnt leaves ash. it was, therefore, deemed that wood was composed of pure wood ( ash ) and phlogiston. iron on the other hand consisted of rust, the pure form of the metal and phlogiston. the impurities arose where the remains could not be defined as either the pure material or phlogistonated air. gases that dissolved in water were a prime example of this kind of impurity, materials that did not meet the criteria of either pure base or phlogiston. the theory maintained its position in scientific thought for 100 years, though throughout that period loopholes were identified and then carefully patched up with new variations and terms, like the impurities of fixed and foul air. objections were consistently countered with new information from phlogistonists who were not keen to see their theories blown apart. ultimately it was the work of french scientist antoine laurent lavoiser, in the late 18th century, which led to the systematic tearing apart of the phlogiston theory. his astute and systematic experimentation gave weight to gathering force of the antiphlogistonist movement. what replaced it were theories around oxygen and the reactions experienced by materials in the presence of this life - giving gas. experiments switched from purely observational efforts to quantitative analysis that tried to qualify changes and reactions without giving in to notions of fancy expanded from what the eyes


in this module we need to be a little bit more precise about temperature and heat energy than we have been so far. heat energy is usually measured in terms of calories. the calorie was originally defined as the amount of energy required to raise one gram of water one degree celsius at a pressure of one atmosphere. this definition is not complete because the amount of energy required to raise one gram of water one degree celsius varies with the original temperature of the water by as much as one percent. since 1925 the calorie has been defined as 4. 184 joules, the amount of energy required to raise the temperature of one gram of water from 14. 5 degrees celsius to 15. 5 degrees celsius. for our purposes here we can ignore the fact that the effect of one calorie of energy varies depending on the temperature of the water. newton ' s model of cooling can be thought of, more precisely, as involving two steps. the picture above shows a brick whose length is four centimeters. we mentally divide the brick into two unequal pieces. the lefthand piece has a length of one centimeter and the righthand piece has a length of three centimeters. heat is flowing across the mental boundary between the two pieces from left to right at the rate of a calories per hour. as a result the average temperature of the lefthand piece is changing at the rate of - ka degrees celsius per hour. the constant k depends on the composition of the brick and its cross - sectional area. the average temperature of the righthand piece is changing at the rate of ka / 3 degrees celsius per hour. the three in the denominator comes from the fact that since the righthand piece is three times the length of the lefthand piece, its mass is three times as big.