that the mirrors form. as you make the angle between the mirrors smaller, the light bounces back and forth more times, and you see more images. the illustration below shows how an image is formed in the corner of two mirrors at 90 degrees. light rays bounce off each mirror at the same angle that they hit the mirror : physicists say that the angle of reflection is equal to the angle of incidence. mirrors at other angles behave similarly, but the ray diagrams may get more complex. the inside corner of a corner reflector ( where the three mirrors meet ) sends light back parallel to its original path. if you pointed a thin beam of laser light right near the corner, the beam would bounce from mirror to mirror and then exit parallel to the entering beam. light from the center of your eye bounces straight back to the center of your eye, so the image of your eye seems to be centered in the corner made by the mirrors. in a corner reflector, multiple reflections reverse the image and invert it. corner reflectors are used to make safety reflectors for cars, bicycles, and signs. corner reflectors have also been used to bounce laser beams back to the earth from the surface of the moon. throw a tennis ball into the corner of a room. it should return to you after bouncing off the three surfaces. tape five square mirrors together with the mirrored surfaces facing inward to form a box. place a sixth mirror, turned at a 45 - degree angle, over the open side so you can look into the box and also let some light in. this combines the look into infinity snack with this corner reflector snack. try other configurations of mirrors in three dimensions and see what you can discover. to do a quantitative experiment, mark the following angles on a piece of cardboard : 180 degrees, 90 degrees, 60 degrees, 45 degrees, 36 degrees, 30 degrees, and 20 degrees. these angles are chosen so that when they are divided into 360 degrees they produce an even integer. mount the hinged mirrors at each of these angles and place an object betvveen them. count the number of images you see. you should be able to verify the following rule : 360 divided by the angle between the mirrors gives the number of images, plus one. at 60 degrees, for example, 360 / 60 = 6, so you should see five images of the object.


the explanatory modeling tasks and recommended strategies contained in the current service packages offered by gln consulting are refinements of student engagement activities originally used by dr. newsome in his own teaching. since his retirement from teaching, these activities and strategies have been refined through an extensive, integrative analysis of selected research on creative problem solving by expert scientists and college students and research on how scientific explanations enhance understanding of a target domain. the studies on creative problem solving that were selected for this analysis focus on the kinds of problem solving activities that have been shown to contribute to conceptual innovation in science and to promote greater depth of understanding by students ( clement, 2009 ). these kinds of problem solving activities share two important characteristics. first, they require the use of modeling procedures that go beyond the “ empirical discovery ” of patterns in bodies of data ( observations ) to include the use of theoretical constructs to derive hypotheses that explain the occurrence of those patterns. second, they require reasoning about novel situations in ways that are not amenable to the application of practiced procedures for solving particular kinds of problems ( i. e. they are nonalgorithmic ). the selected research on the nature of scientific explanations includes philosophical analyses of the construction and use of explanations by scientists across disciplines. the selected studies of expert problem solving by scientists focus on ( 1 ) examining the problem solving activities that advance scientific understanding and ( 2 ) aligning these activities with those that nonscientists use to solve problems and understand the world. these studies use methods and analytic techniques from history, philosophy, and cognitive science to establish a cognitive basis for creative scientific reasoning that is continuous with everyday reasoning activities. historical records of the practices of preeminent scientists and ethnographic observations of current scientific practices provide information about the kinds of problem solving activities that promote theoretical understanding within the scientific community. philosophical analysis of these problem solving practices describe them as forms of nonformal reasoning like analogical modeling and simulative model - based reasoning. cognitive analyses of these “ model - based reasoning ” practices help to align them with the cognitive resources ’ and limitations that scientists share with other humans. taken together, the results of these interdisciplinary studies indicate that advances in theoretical understanding can be produced through a dynamic, incremental process of model construction, manipulation, evaluation, and revision. traditional notions of scientific reasoning as the application of symbolic and mathematical logic are too narrowly constrained to account for advances in theoretical understanding. to account for conceptual innovation and change, these philosophical notions of reasoning must be extended to


, manipulation, evaluation, and revision. traditional notions of scientific reasoning as the application of symbolic and mathematical logic are too narrowly constrained to account for advances in theoretical understanding. to account for conceptual innovation and change, these philosophical notions of reasoning must be extended to include analogical reasoning activities that involve model construction, evaluation, and adaptation. models are representations of phenomenon, systems, or situations that highlight epistemicaly relevant features of these targets. the function of a model is to afford epistemic access to problem relevant features of the target and display the significance of those features to potential problem solutions. theory development and change in science typically involves the construction, manipulation, evaluation, and revision of dynamic models that serve as structural or functional analogs of real world systems rather than axiomatic systems or propositional networks ( darden, 1991 ; giere, 1988 ; morgan & morrison, 1999 ). the scientific practices that were found to contribute to advances in theoretical understanding share several key features that are invariant across scientific disciplines. cognitive analyses of these key features suggest that they reflect the extension and refinement of the human capacity for simulative thinking through modeling ( e. g. dunbar, 2001, 2002 ; nersessian, 2005, 2008 ). several studies have shown that simulative model - based reasoning plays a key role in the thinking of both scientists and students ( e. g. clement, 2009 ; dunbar, 2001 ; nersessian, 1995 ). the studies selected for analysis examined the extent to which nonformal reasoning processes used by scientists to advance theoretical understanding occur naturally in students and how students ’ ability to use these processes can be utilized in instruction. the primary focus of these selected studies was on students ’ use of the kinds of representational and inferences processes employed in scientific practice as opposed to the more formal expressions that appear in scientific articles. the results of these studies indicate that students have the natural ability to perform most of the nonformal reasoning activities that contribute to conceptual change in science and learning to perform these activities can help them to achieve greater depth of understanding of a scientific discipline. these results also indicate that the kinds of model - based reasoning activities that contribute most to the achievement of theoretical understanding in students are those that involve the generation, manipulation, evaluation, and adaptation of models that represent explanatory mechanisms. philosophers of science have long debated the nature of explanation, but most contemporary ones agree that explanations enhance understanding of phenomena by situating them within the organizational structure ( logical or causal ) of a target domain ( salmon


models that represent explanatory mechanisms. philosophers of science have long debated the nature of explanation, but most contemporary ones agree that explanations enhance understanding of phenomena by situating them within the organizational structure ( logical or causal ) of a target domain ( salmon, 1998 ; strevens, 2008 ). the studies selected for analysis are those that focus on the construction and use of explanations by psychologists ( e. g. bechtel, 2008 ; cummins, 1883 ) and neuroscientists ( e. g. craver, 2001, 2007 ; machamer, darden, & craver, 2000 ). bechtel, w. ( 2008 ). mental mechanisms. lawrence erlbaum associates. clement, j. ( 2009 ). creative model construction in scientists and students. springer - verlag. craver, c. ( 2001 ). role functions, mechanisms, and hierarchy. philosophy of science, 68, 53 - 74. craver, c. ( 2007 ). explaining the brain : mechanisms and the mosaic unity of neuroscience. oxford cummins, r. ( 1983 ). the nature of psychological explanation. mit press. darden, l. ( 1991 ). theory change in science : strategies from mendelian genetics. oxford university dunbar, k. ( 2001 ). what scientific thinking reveals about the nature of cognition. in k. crowley, c. scheen, & t. okada ( eds. ), designing for science : implications from everyday and professional settings ( pp. 115 - 140 ). lawrence erlbaum associates. giere, r. ( 1988 ). explaining science : a cognitive approach. university of chicago press. machamer, p. darden, l., & craver, c. ( 2000 ). thinking about mechanisms. philosophy of science, 67, morgan, m. & morrison, m. ( eds. ), models as mediators. cambridge university press. nersessian, n. ( 1995 ). should physicists preach what they practice? : constructive modeling in doing and learning physics. science and education, 4, 203 - 226. nersessian, n. ( 2005 ). interpreting scientific and engineering practices : integrating the cognitive, social, and cultural dimensions. in m. gorman, r. tweney, d. gooling, & a. kincannon ( eds. ), scientific and technical thinking. lawrence erlbaum associates. nersessian, n. ( 2008 ).


type terminology, where ' gas chamber ' simply meant a place for human extermination. they could hardly have done otherwise, because doubt over ' the holocaust ' is a crime in poland. the dcs were alluded to as ' facilities for the fumigation of prisoners ' clothes. ' the polish team went to a lot of trouble, with some sixty measurements mostly measured thrice, and was the only study which obtained permission to take the samples. it omitted two things in its conclusions : any allusion to the birkenau dc ( ' facilities for the fumigation of prisoners ' clothes ' ) where it had found greatly - elevated cyanide levels over the ahgcs ; and, the insoluble cyanide that was bound to iron. in regard to both of these it cited the prussian blue ferric ferrocyanide complex, leaving open the possibility that is had some quite extraneous source and was therefore to be avoided. the 1947 method used by markiewicz et. al. was given by joseph epstein and published in a us chemistry journal. " it was a procedure whose limit of accuracy was given as 0. 2 micrograms per ml. to expel the cyanide from brickwork and then dissolve it into a solution suitable for measuring it, involves an order - of - magnitude dilution at least, so that one would not expect to obtain an accuracy less then one ppm in the brickwork, using this method. any claim that this decades - old titration and colorimetric method using thiocyanate can find parts per billion has to be spurious. iv. desjardin analyses leuchter dan desjardins, after carefully retracing the steps of leuchter on a 1996 visit to auschwitz ' ", and watching the film that had been made of leuchter ' s sampling ' ", divided the samples 1 - 31 into two groups : those which had been exposed and open to the elements over the decades ( n = 20 ), and those which were more protected in sheltered, unexposed locations : ' leuchter ' s samples, numbered 25 through 31, extracted from crematorium i... taken from a facility which was not destroyed and has remained intact since the end of the war, were not exposed to the elements. the same might be said for samples 4, 5 and 6 taken from crematorium ii. leuchter removed these samples from a pillar, wall and ceiling which,


los alamos, n. m., sept. 2, 2004 – university of california scientists working at los alamos national laboratory have demonstrated a way to use the random fluctuations that exist naturally in all magnetic systems to perform magnetic resonance studies without disturbing the system ' s natural state. conventional magnetic resonance techniques, such as those used in magnetic resonance imaging ( mri ) machines, require the excitation and absorption of specific radio - frequency waves by atoms in a magnetic field. these absorption patterns can be used to reveal molecular and magnetic structure. the find could pave the way for perturbation - free magnetic resonance imaging techniques that are useful in fields like nanotechnology and quantum information science where systems containing only a few atoms are becoming commonplace and their associated magnetic fluctuations play an increasingly dominant role. in research reported in today ' s issue of the scientific journal nature, los alamos scientists scott crooker, dwight rickel, alexander balatsky and darryl smith explain how seemingly random fluctuations in an ensemble of magnetic spins – – called spin noise – – can actually be exploited to perform detailed magnetic resonance, without disturbing the spins from a state of thermal equilibrium. using a laser technique known as faraday rotation, the scientists measured the spectrum of spin noise in vapors of magnetic rubidium and potassium atoms. the noise spectrum alone revealed the complete magnetic structure of the atoms. according to greg boebinger, director of the national high magnetic field laboratory ( nhmfl ), " this work is especially important because as devices shrink in size to the nanoscale regime, fewer atoms and spins dominate the device behavior and noise processes become more prominent. by drawing on the fluctuation - dissipation theorem, the work at los alamos firmly establishes the idea that one scientist ' s noise is another scientist ' s signal. " single electron spin this work, performed at the national high magnetic field laboratory facility at los alamos, provides a demonstration of the physical relationship known as the " fluctuation - dissipation theorem, " which proposes that it is possible to " listen " very carefully to the tiny, intrinsic thermal or quantum - mechanical fluctuations of a physical system. those fluctuations reveal a number of the properties of that system without having to disturb it from its natural resting state. typically, in devices like mri systems, an electromagnetic source must be used to " perturb " the spins of atoms so that they resonate in synchrony at radio frequencies, which are then recorded to create mri scans. alex lacerda, director of the nhmfl


| tweet | guiding light a new kind of glass pane containing liquid crystal droplets can guide and manipulate beams of light. 25, 2003 : the information age rides on beams of carefully controlled light. because lasers form the arteries of modern communications networks, dexterous manipulation of light underpins the two definitive technologies of our times : telecommunications and the internet. now researchers at harvard university have developed a new way of steering and manipulating light beams. using droplets of liquid crystals - - the same substance in laptop displays - - the scientists can make a pane of glass that quickly switches from transparent to diffracting and back again. when the pane is transparent a laser beam passes straight through, but when the pane is diffracting, it splits the beam, bending it in several new directions. " telecommunications could be one application, but at this point we ' re still looking at the basic properties of these droplets. their potential is great, and it ' s hard to imagine all the ways engineers might use them, " says david weitz, gordon mckay professor of applied physics at harvard university and lead scientist for the nasa - supported research. beyond telecommunications, one could imagine this light - steering ability being useful in astronomy. for example, these liquid - crystal panes could be used in reverse to combine ( rather than split ) beams of light from multiple telescopes. combining light from many telescopes, a technique called interferometery, is a good way to search for distant planets around other stars. another application : a liquid crystal pane held in front of the mirror of a telescope could be used to " unwrinkle " light that has passed through earth ' s turbulent atmosphere. such adaptive optics telescopes could gain a crystal - clear view of the heavens from earth ' s surface. the many uses of steering light are part of the reason that nasa recently decided to award weitz and colleagues a grant for this research. in addition, nasa can provide a unique environment for experimenting with liquid crystals : low gravity. " we ' ve already seen several exciting results from fluid physics experiments done in earth orbit, " says brad carpenter, lead scientist for nasa ' s physical sciences research division. " this latest project of dr. weitz, who has already completed some successful experiments on the international space station ( iss ), was selected for funding with the vision of aiding advances in optical information technologies. " all droplets are created equal liquid crystals are a class of liquids whose molecules are more orderly than molecules in regular fluids. because of this orderliness, when these


iss ), was selected for funding with the vision of aiding advances in optical information technologies. " all droplets are created equal liquid crystals are a class of liquids whose molecules are more orderly than molecules in regular fluids. because of this orderliness, when these liquids interact with light, they can affect the light like crystals do. left : the droplets of liquid crystal in the harvard group ' s experiments, like those shown here, are of equal size and arranged in a regular pattern. image courtesy harvard university. a technique invented by weitz and his colleagues produces equal - sized droplets of liquid crystal, each about a dozen microns across ( a micron is one thousandth of a millimeter ). because they ' re all the same size, packing the droplets together on a glass plate causes them to arrange themselves into a honeycomb it ' s this regular pattern that gives sheets of liquid crystal droplets their light - steering ability. making droplets of liquid crystals is nothing new ; the basic technology has been around since the mid - 1980s. today you can find such droplets in the window - walls of some executives ' offices. with the flip of a switch, the office ' s transparent windows magically change to opaque walls somewhat like frosted glass. " the big difference between what we do and what has been done before is that older - style glass panes contain a random distribution of drops and drop sizes - - tiny ones and big ones. they ' re not ordered at all, " explains darren link, one of the scientists on the research team. without any order in the drop size and spacing, these older liquid crystal systems simply scatter light in all directions - - hence the frosted - glass effect. " in our case, because we make all the drops the same size, we ' re able to steer light in specific directions, " link says. left : light striking a surface after passing through the flat sheet of liquid crystal droplets doesn ' t appear as a single dot, but is split and bent to produce a patterns of dots. image courtesy harvard university. the molecules in a liquid crystal droplet are long and rod - shaped. an electric field can steer these rods ( much as a magnetic field moves a compass needle ) and so control how they guide rays of light passing through them. steering light at will is useful enough, but link suspects that the most interesting results will come from the next phase of their research. exploring another dimension " where i think the interesting new physics is going to be is in getting away from having a 2 - d sheet and


will is useful enough, but link suspects that the most interesting results will come from the next phase of their research. exploring another dimension " where i think the interesting new physics is going to be is in getting away from having a 2 - d sheet and going into 3 - dimensional ordered structures, " link says. " from now on our research will focus on doing this with real 3 - d ordered structures using smaller particles. " link and colleagues aren ' t sure what they ' re going to find when they shine light through several stacked - up layers of these ordered droplets... that ' s what ' s so exciting about doing it! it might split the light up into a rainbow, like a prism, or it might affect the light in a totally unexpected way. but first they need to find reliable ways to arrange the droplets into various 3 - dimensional patterns. this is where low gravity comes in handy. weightlessness greatly simplifies making 3 - d structures from fluid droplets. the tiny droplets have a different density than the liquid in which they are suspended. on earth they ' ll either float or sink, which greatly complicates arranging them into a pattern. in orbit, the lack of buoyancy allows droplets to remain nicely suspended, allowing researchers to explore many configurations that would be difficult or impossible to create on the ground. above : 3 - dimensional stacked layers of liquid crystal droplets could have some novel and useful effects on light that passes through them. image courtesy nasa. weitz says they intend to design a space - experiment and eventually fly it on the iss. first, though, more research on the ground is needed to understand the basic physics of these droplets - - how they respond to the applied electric field, and exactly how those responses affect the passing light. it ' s details such as these that could soon give researchers a new tool to use in their ever - expanding mastery of light. more detailed information - - a short paper offering a more technical explanation of the concept discussed in the article above weitz ' s research group ' s home page - - the experimental soft condensed matter group home page at harvard university liquid crystals and lcds - - an explanation of what liquid crystals are and how they ' re used to make the lcd displays used in laptops and digital watches, from howstuffworks. com. crystals : a tutorial - - information about the history and physics of liquid crystals, from the georgia institute of a. fernandez - nieves, d. r. link, d. rudhardt, and d


key : " s : " = show synset ( semantic ) relations, " w : " = show word ( lexical ) relations display options for sense : ( gloss ) " an example sentence " - s : ( v ) reduce, cut down, cut back, trim, trim down, trim back, cut, bring down ( cut down on ; make a reduction in ) " reduce your daily fat intake " ; " the employer wants to cut back health benefits " - s : ( v ) reduce ( make less complex ) " reduce a problem to a single question " - s : ( v ) reduce ( bring to humbler or weaker state or condition ) " he reduced the population to slavery " - s : ( v ) reduce ( simplify the form of a mathematical equation of expression by substituting one term for another ) - s : ( v ) reduce ( lower in grade or rank or force somebody into an undignified situation ) " she reduced her niece to a servant " - s : ( v ) reduce, come down, boil down ( be the essential element ) " the proposal boils down to a compromise " - s : ( v ) shrink, reduce ( reduce in size ; reduce physically ) " hot water will shrink the sweater " ; " can you shrink this image? " - s : ( v ) reduce ( lessen and make more modest ) " reduce one ' s standard of living " - s : ( v ) reduce, scale down ( make smaller ) " reduce an image " - s : ( v ) deoxidize, deoxidise, reduce ( to remove oxygen from a compound, or cause to react with hydrogen or form a hydride, or to undergo an increase in the number of electrons ) - s : ( v ) reduce, tighten ( narrow or limit ) " reduce the influx of foreigners " - s : ( v ) repress, quash, keep down, subdue, subjugate, reduce ( put down by force or intimidation ) " the government quashes any attempt of an uprising " ; " china keeps down her dissidents very efficiently " ; " the rich landowners subjugated the peasants working the land " - s : ( v ) reduce ( undergo meiosis ) " the cells reduce " - s : ( v ) reduce ( reposition ( a broken bone after surgery ) back to its normal site ) - s : ( v ) reduce ( destress and thus weaken a sound when pronouncing it ) - s : ( v


combining the media of photography, sculpture, and drawing, the works of hungarian - born artist attila csorgo offer viewers an ironic and humorous introduction to questions of science and technology. the results are often unexpected, amusing, or even poetical. in long - term experiments the artist explores branches of science such as kinetics, optics, or geometry to examine questions of perception ; and on this basis he develops his theories about the construction of reality. his photographs capture sequences of motion or energetic processes, which appear as traces of light, making phenomena visible that, under normal conditions, are not or only barely perceptible to the human eye. while such processes rely on scientific and mathematic calculations, the artist frequently assembles his technological arrangements from everyday objects and materials. element by element, his transparent systems sharpen our understanding of things we usually take for granted. the fundamental difference between my work and that of an engineer is that the systems i build are transparent, says attila csorgo about his artistic work : and my research, i. e. the processes yielding these results, is open to view. unlike a computer or other technical devices where we do not know what goes on inside them. i dont build black boxes but try to open up closed systems, at least to a certain degree, even if the mathematical calculations and conceptual considerations behind them are not always visible. my works very obviously combine art and engineering, although what i do is unquestionably art. for the exhibition at the vienna secession, attila csorgo created an experimental clock - work which continues his examination of light and motion combined. at the interface of visual arts and science, his work on phenomena of perception finds its focus in the lemniscate, the figure eight lying on its side. both mathematical symbol and poetical shape, the lemniscate is a symbol of infinity shaped like a horizontal 8. what csorgo has built is a time machine which can be read as a sculpture or a three - dimensional drawing, a moving picture or simply a scientific experiment. if we consider the things that humankind has created, so the artist in an interview : these are mostly very transient phenomena. the forms of mathematics, in contrast, are fairly stable, if not indeed the most stable of all. their historical distillation endows these mathematical ideas with a noble character. this may be one reason why i like using poor materials to realize my works : it creates a strong contrast between transient thought and concrete material. occurrence graph i ( triangle


all. their historical distillation endows these mathematical ideas with a noble character. this may be one reason why i like using poor materials to realize my works : it creates a strong contrast between transient thought and concrete material. occurrence graph i ( triangle ), 1998 occurrence graph ii ( circle ), 1998 occurrence graph ii ( lemniscate ), 1998 kinetic wall object ; lamp, aluminium disc, electric motor, spinning components, each 67 x 35 x 23 cm. the occurrence graph series is based on the interaction of mutually cooperating graphs. two black discs pierced by the lines of seemingly meaningless graphs overlap in an area in the shape of a plum - pit which only allows the light of the lamp positioned behind the discs to penetrate when two graphs are congruent. the system can be set in motion with the aid of an electric motor. the motion reveals that the graphs actually form regular geometrical patterns ( triangle, circle, lemniscate ). the resulting phenomenon is a double or, more precisely, a quadruple one : the rotation enables the graphs on the two discs to cooperate and to achieve, so to speak, a new phase of matter. the stable and seemingly meaningless image that is visible when the discs are not moving is transformed into an ordered one that, however, only seems to be stable, since the discs need to be in motion for it to emerge. * photo tower ( trajectory reconstruction ), 2008 - 3d print, synthetic resin, 31 x 50 x 5 cm photo tower ( trajectory dice ), 2008 lambda print, 120 x 160 cm the detailed shots in photo tower and the simple spatial structure of the construction make it possible to reconstruct the trajectory of the falling dice. the photographs taken from opposite viewpoints are logically complementary and, placed side by side, produce continuous diagrams. when we project the diagrams onto one anotherthis time in virtual spacewith respect to the structure of the tower, then the corresponding intersections of the projective surfaces will reproduce the original spatial curve defined by the luminous spots flight path. in this way, the image of movement turns into a sculpture of movement. * clock - work, 1993 alarm clocks, wooden box, 5. 5 x 11. 5 x 10. 3 cm attila csorgo says about clock - work : i assembled two traditional, analogue alarm clocks together as one. the clocks gears are joined together in such a way that one mechanism turns the other, resulting in a symmetrical parallel movement : one of the hands is rotating clockwise, while the other hand is turning counter


assembled two traditional, analogue alarm clocks together as one. the clocks gears are joined together in such a way that one mechanism turns the other, resulting in a symmetrical parallel movement : one of the hands is rotating clockwise, while the other hand is turning counter - clockwise. i only used the second hands of the clocks. * slanting water, 1995 b & w photograph, 28 x 40 x 5 cm slanting water shows an ordinary phenomenon under extraordinary conditions. a glass filled with water standing on a table is a fairly ordinary sight. the level of the water ( a horizontal plane ) and the vertical plane form the basis of our coordinate systemwhat mathematicians describe as coordinate axes. however, while mathematical coordinates can be rotated, our everyday system of coordinates is less flexible. slanting water presents the possibility of an alternative system. the explanation for the apparently impossible phenomenon is that the table is revolving, which the photograph does not show. * spherical vortex is the path of a flashlight bulb made by connecting three separate spinning movements of different velocity. starting from a single point, the light source spirals around an increasing radius to describe a sphere. having reached its outer limit, the light spirals back to the point / source state. alongside the moving device, four photographs are on display which were made with different exposures ( consecutive or long exposure ), revealing the path of light that is invisible to the naked eye. * clock - work, 2011 - kinetic construction ; 2 parabolic reflectors, electronic elements, 2 tripods, wooden elements ; 11 drawings clock - work is the dual projection of a given group of objects, two views of the same assemblage at right angles to each other, appearing as silhouettes on two walls of a room. the subject of the experiment is an amorphous configuration, a strip ending in itself, with one two - dimensional projection showing a circle, the other the symbol of the infinite, the horizontal figure eight or lemniscate. a rod moves along the two - dimensional line of the fixed object, as if it were the hand of a clock, scanning or drawing the figure. there is an emphasis on that the structures used for projecting are not high - tech equipment but the everyday tools of a contemporary non - professional experimenter : a tripod, a simple motor, light, a mirror, a clamp, rods, wires, bolts. although the experimental structure works mechanically as a professional machine, every bit of the environment bears the marks of its creators hands. * * attila csorgo outline at


( 1 ) a generic term for an extremely thin flexible display that can be rolled up. there are several technologies in the works, and this type of display is expected to become mainstream by 2015. | this oled display screen unrolled out of a pen may seem far fetched, but such products are expected to be commercialized in a few years ( see ( 2 ) a paper - thin display technology that uses charged black and white elements oriented toward the viewer when a charge is applied and which retain their formation without power. the first electronic paper was developed at xerox ' s palo alto research center ( www. parc. com ) in the 1970s. it used a thin sheet of xerox gyricon plastic, containing millions of charged beads with black and white hemispheres. when the paper was fed through a " printer, " a voltage pattern was applied, and the beads were oriented toward their black or white side, or half way for gray. although the gyricon media inc. subsidiary was created to develop the technology, it never worked well enough to become a product. in the 1990s, another electronic paper technology was developed at mit media labs that placed the black and white elements inside a microcapsule. e ink corporation was created in 1997 to further develop and market the method, and it succeeded ( see e ink ). nick sheridan, who invented the electronic paper at parc, and fereshteh lesani show the first roll of paper produced by 3m. ( image courtesy of palo alto research center. ) in 2008, epson demonstrated a super - high - resolution prototype display using e ink technology. at 385 dpi, this 13. 4 " display provides an outstanding 3104 x 4128 pixel resolution. ( image courtesy of seiko epson corporation. )


come hard, and it was a hundred and twenty years after clairaut before the correct way to represent a space curve by intrinsic natural equations was finally discovered - - - by the french mathematicians joseph alfred serret and frederic - jean frenet. the idea is that at each point of a space curve one can define two numerical quantities called curvature and torsion. the curvature of a space curve is essentially the same as the curvature of a plane curve : it measures how rapidly the curve is bending to one side. the torsion measures a curve ' s tendency to twist out of a plane. but what exactly is meant by " bend to one side, " and " twist out of a plane "? which plane? the idea is that at each point p of a space curve you can define three mutually perpendicular unit - length vectors : the tangent t, the normal n, and the binormal b. t shows the direction the curve is moving in, n lies along the direction which the curve is currently bending in, and b is a vector perpendicular to t and n. ( in terms of the vector cross product, t cross n is b, n cross b is t, and b cross t is n. ) for space curves we ordinarily work only with positive values of curvature, and have n point in the direction in which the curve is actually bending. ( in certain of the analytical curves well look at later we relax this condition and allow negative curvature of space curves. ) taken together, t, n and b make up the so - called " moving trihedron of a space curve ". in figure 3 we show part of a space curve ( actually a helix ) with several instances of the moving trihedron. so that it ' s easier to see the three - dimensionality of the image, we draw the curve as a ribbon like a twisted ladder. the curve runs along one edge of the ladder, and the rungs of the ladder correspond to the directions of successive normals to the curve. figure 3 : the moving trihedron of a space curve : t the tangent, n the normal, and b the binormal. to understand exactly how the normal is defined, it helps to think of the notion of the " osculating " ( kissing ) plane. at each point of a space curve there is some plane that best fits the curve at that point. the tangent vector t lies in this plane, and the direction perpendicular to t in this plane holds the normal n. the binormal is a vector perpendicular to


intoxication of the brain produces well - known mental impairments. electrical stimulation of the exposed human cortex can evoke images and sounds, and even a virtual reliving of past experiences ( penfield and roberts 1959 ). modern brain - imaging techniques, such as functional magnetic - resonance imaging, have connected certain mental states with heightened activity in specific brain regions ( kamitani and tong 2005 ; binder, et al. 2005 ; ishai, et al. 2005 ). how brain activity generates mental states is as much of an enigma today as it was more than a half - century ago when the great neurophysiologist charles sherrington ( 1951 ) said in wonder, “ how can a reaction in the brain condition a reaction in the mind? ” more recently, the physicist erich harth ( 1983 ) expressed this enigma when he wrote “ mind is like no other property of physical systems. it is not just that we don ’ t know the mechanisms that give rise to it. we have difficulty seeing how any mechanism can give rise to it. ” transmission and readability of prayers the brain, an electrochemical organ, consists of matter and energy, but the mental states that are the epiphenomena of its physiological processes are neither material substances nor forms of energy. sherrington ( 1951 ) expressed this “ scientific position ” in saying, “ thoughts, feelings, and so on are not amenable to the energy ( matter ) concept. they lie outside it. ” if thoughts — including silent prayers — are not a form of energy, then there is no known natural means by which they could be transmitted beyond ourselves or read within us. still, many credulously believe that some people ( especially so - called “ psychics ” ) can read minds and that thoughts can be transmitted from one person to another by mental telepathy or “ extrasensory perception ” ( esp ). perhaps this belief has been fostered by the seemingly substantive and energetic presence of our thoughts. but numerous experiments during some 150 years of research have not validated esp and have left a wake of spurious statistical analyses ( lilienfeld 1999 ; paulos 1990 ). though thoughts and prayers are neither transmissible nor readable by any natural means, could they be known to a supernatural being? evidence for or against this can be obtained by determining whether prayers are followed by what was solicited by them. only proper scientific studies, however, can provide reliable evidence by excluding chance occurrences, and biases from the results.


ultra low power logic design with quantum cells one of the most promising nanotechnologies which can replace the present transistor based cmos technology is the quantum - dot cellular automata. the major advantages of this technology are lesser power dissipation, improved speed and dense structures. currently all logic gates are based on cmos technology. with the current pace of scaling cmos technology is set to hit a roadblock in the next few years, where it cannot be further scaled down due to several reasons like tunnel currents, quantum effects, subthreshold leakage, short channel effects, fabrication costs and interconnect delay etc. logic design with quantum dots is one of the most recent technologies being researched which allows scaling to continue to atomistic dimensions. in this particular logic design approach quantum cells are arranged in particular fashion to define the logic. each quantum cell consists of 4 quantum dots. owing to electron repulsion and coulomb blockade electrons are aligned automatically such that the energy of the system is minimum. qca cell and operation : quantum - dot cellular automata ( qca ) is based on field coupled computing. states of a cell change due to mutual interactions of either electrostatic or magnetic fields. qca cell is the fundamental component of qca logic. each qca cell is made of four quantum dots in which two mobile electrons can be trapped which can tunnel between the dots. due to the repulsion between the electrons, two electrons always take up the diagonal positions. binary levels are represented by the positions of the electrons inside the cell unlike the voltage or current levels as in the cmos. figure 1 show the structures of quantum cell with two different polarizations ( electrons are shown with black filled circular dots ). majority gate and inverter are the two basic logic devices of qca. fig. 2 shows the structure of the majority gate with 3 inputs, driver cell and output cell. computation starts by driving the driver cell to the lowest energy state. input cell changes its state by the signal which arrives towards the driver cell. driver cell always gets the binary value of majority of input signals since it is where the repulsion for the mobile electrons in driver cell is at minimum and output follows the state of driver cell. fig. 2 majority gate the logic function for the majority gate is given by m ( a, b, c ) = ab + bc + ca with a, b, c as boolean variables. in this way two input and, or gates can be designed by keeping the third variable as either 0 or


gate is given by m ( a, b, c ) = ab + bc + ca with a, b, c as boolean variables. in this way two input and, or gates can be designed by keeping the third variable as either 0 or 1 respectively. inverter is the other basic logic device of qca. if cells are placed diagonally to each other then they will have opposite polarizations. qca inverter is designed by this characteristic, such as shown in fig. 3. fig. 3. qca inverter in the case of qca, the clock signal modulates the inter dot barrier. qca designs rely on a set of 4 clocks, phase shifted with respect to each other. clock is used to. push. information from inputs to the output by modifying the cell tunneling energy. qca circuits have a four phase clock as against the cmos which has only two states high and low and all the four phases have a phase shift of 90°, as shown in fig. 4. power to the qca circuit comes from the clock itself unlike external power supply in case of cmos. to assign the clock, the qca circuit is divided into four sub arrays and a single potential modulates the inter - dot barriers in all the cells present in given array. clock feature allows the sub array to perform a certain calculation at which it does not have influence from its successor and it acts as input to the next sub array, adding the feature of pipelining. the four phases of clock correspond to switch, hold, release, and relax. in switch phase, the barriers are raised and the qca cells become polarized according to the state of input drivers. in the hold phase, the barriers are kept high so that the cells in that sub array retain their values. during the release phase, the barriers are lowered and the cells are allowed to relax to unpolarised state. in the final relax phase the barriers kept on low and the cells power dissipation in qca : unlike computation mechanisms that involve the transfer of electrons, as in cmos gates, qca computation does not involve electron transfer between adjacent qca cells. hence power dissipation is very less in circuits designed with qca cells. since only few electrons are involved in qca computations, it is susceptible to thermal issues. therefore it is important to consider power as an important parameter during the qca design process. the power loss in clocked qca circuits are classified as switching power and leakage


what is triple des? 3des ( also “ triple des ” ) is an open encryption standard that offers strong encryption at 112 - bit and 168 - bit strengths. 3des is a symmetric encryption algorithm often used today to secure data in motion in both ssh and ssl / tls. ( after asymmetric key exchange is used perform the handshake in a ssh or ssl / tls sessions, data is actually transmitted using a symmetric algorithm such as 3des. ) 3des is also often used today to secure data at rest in smime, pgp, as2, strong zip encryption and many vendor - specific implementations. ( after asymmetric key exchange is used to unlock a key on data at rest, data is actually read or written using a symmetric algorithm such as 3des. ) nist ‘ s aes competition was held to find a faster and stronger replacement for 3des. however, 3des has not yet been phased out and is expected to remain approved through 2030 for sensitive government information. ( only the 168 - bit version is currently allowed ; permitted use of the 112 - bit version ceased january 1, 2011. ) nist validates specific implementations of 3des under fips 140 - 2, and several hundred unique implementations have now been validated under that program. the 3des algorithm itself is specified in fips 46 - 3. see the wikipedia entry for 3des if you are interested in the technical mechanics behind 3des. best practice : all modern file transfer clients and file transfer servers should support fips - valided aes, fips - validated 3des or both. ( aes is faster, may have more longevity and offers higher bit rates ; 3des offers better backwards compatibility. )


‘ artificial atoms ’ allow for sensing magnetic fields of individual cells february 13, 2013 researchers in spain and australia have developed a new technique that similar to mri but with the high resolution and sensitivity need to scan individual cells. the researchers, from the institute of photonic sciences ( icfo ), in collaboration with the csic and macquarie university in australia, are led by icfo prof. romain quidant. they used “ artificial atoms ” — diamond nanoparticles doped with nitrogen impurity — to probe very weak magnetic fields such as those generated in some biological molecules. a conventional mri registers the magnetic fields of atomic nuclei in our bodies which have been previously excited by an external electromagnetic field. the collective response of all of these atoms makes it possible to diagnose and monitor the evolution of certain diseases. however, mri is limited to a resolution of millimeters. the new technique extends the resolution at the nanometer scale ( nearly one million times smaller than the millimeter ), making it possible to measure very weak magnetic fields, such as those created by proteins. “ our approach opens the door for the performance of magnetic resonances on isolated cells which will offer new sources of information and allow us to better understand the intracellular processes, enabling noninvasive diagnosis, ” explains michael geiselmann, icfo researcher who conducted the experiment. near - absolute - zero temperatures not required until now, it has only been possible to reach this resolution in the laboratory, using individual atoms at temperatures close to absolute zero ( approx. - 273 degrees celsius. ) individual atoms are structures that are highly sensitive to their environment, with a great ability to detect nearby electromagnetic fields. the challenge these atoms present is that they are so small and volatile that in order to be manipulated, they must be cooled to temperatures near absolute zero, making them useless for ordinary medical diagnosis. artificial atoms used by quidant and his team are formed by a nitrogen impurity captured within a small diamond crystal. “ this impurity has the same sensitivity as an individual atom but is very stable at room temperature due to its encapsulation. this diamond shell allows us to handle the nitrogen impurity in a biological environment and, therefore, enables us to scan cells, ” says quidant. to trap and manipulate these artificial atoms, researchers use laser light. the laser works like tweezers, leading the atoms above the surface of the object to study and extract information from their tiny magnetic fields. the new technique could revolutionize the field of medical imaging, allowing for substantially


| atlas reaches out | | contact : paul preuss, firstname. lastname @ example. org | the international atlas collaboration numbering 1, 800 participants from more than 150 universities and laboratories in 34 countries recently reelected michael barnett of berkeley lab ' s physics division and erik johansson of stockholm university as cochairs of the atlas education and outreach program. their mission is to explain to a diverse audience " everyone from high - school students to government science ministers, " barnett says what kinds of science the atlas experiment was designed to explore and how it will do its job. atlas is the largest of the detectors now under construction as part of the large hadron collider ( lhc ) at cern, the european laboratory for particle physics near geneva, switzerland. the big proton - proton collider, a ring - shaped accelerator 27 kilometers in circumference, is not scheduled to be switched on until 2007, but when that happens, barnett warns, watch out. " the lhc has seven times the energy of fermilab, 14 tev versus 2 tev " tev stands for tera ( or trillion ) electron volts " and even running at a fraction of its design energy, it will produce many times the number of top quarks, " barnett says. as for new discoveries, " it will see what it ' s going to see very fast. " one of the most sought - after creatures in the particle zoo is the higgs boson ( or bosons ), the particles whose interactions with other particles are thought to be responsible for their mass. yet, says barnett, " we actually want to downplay finding the higgs, " not because the higgs isn ' t important but because " its discovery will be just one of many things we ' ll learn including the completely unexpected. " among the wilder possibilities proposed by theorists is the production of copious short - lived miniature black holes, formed by the concentration of enormous amounts of energy in small spaces as the proton beams collide inside atlas. rapidly evaporating black holes would announce their presence with a distinctive spray of particles. other far - out discoveries might include extra dimensions of space. some theorists propose that gravity is so much weaker than the other forces because these forces are confined to our familiar three - dimensional space, whereas gravity is diluted by operating in extra spatial dimensions. if so, some debris from energetic collisions inside atlas might vanish into these unseen dimensions, producing asymmetric patterns. perhaps more likely, if a bit less spectacular, will be the


click any word in a definition or example to find the entry for that word 90 % of the time, speakers of english use just 7, 500 words in speech and writing. these words appear in red, and are graded with stars. one - star words are frequent, two - star words are more frequent, and three - star words are the most frequent. the thesaurus of synonyms and related words is fully integrated into the dictionary entries. click on the t button in an entry to review the synonyms and related words for that meaning. more very high mountains the highest ( = tallest ) building the fence is too high to climb over. this is an area of high unemployment. interest rates are very high. casualties were highest near the centre of the earthquake. music was being played at high volume. the risk of the disease spreading is high. temperatures in the high twenties ( = between 27 and 30 degrees ) the pipes contain a high level of lead. a high proportion of the population are immigrants. they expect high standards of care. they ' re known for the high quality of their products. she has a very high opinion of herself. i have the highest regard for him. what is the highest rank in the army? teachers no longer enjoy the high social status they once had. both parties are giving high priority to education in their campaigns. he was high on cocaine. major football tournaments should not really be played in high summer. in the 1980s this was high fashion. it was a day of high drama. this is high politics played for high stakes. a new tv drama series set in the world of high finance this is the british english definition of high. view american english definition of high. a particle that is smaller than an atom and has no electrical charge … to reveal a small part of your intentions in order to attract support, without actually committing yourself to doing anythingadd a word a must for anyone with an interest in the changing face of language. the macmillan dictionary blog explores english as it is spoken around the world today. global english and language change from our blog


reality : new techniques make it possible in april 2000, when ut - battelle assumed the management of oak ridge national laboratory, ornl ' s supercomputer was measured at one teraflop, a then - unimaginable one trillion floating point operations per second. a few years later, the same machine did not rank among the world ' s top 500 supercomputers. in a truly international competition that includes japan, spain and a host of other nations investing in massive computational power for scientific research, high - performance computers have become so big so fast that among some a myth is taking hold : we have raced past the point at which researchers can practically manage such mind - boggling volumes of data generated by trillions of calculations each second. ornl ' s jaguar system, for instance, is capable of more than 260 trillion calculations per second, making the machine ( in a constantly shifting ranking ) in june 2008 the fifth most powerful computer in the world and the third most powerful for open scientific research. funded as part of the department of energy ' s leadership computing facility, ornl ' s jaguar is expected to surpass one thousand trillion calculations per second, or one petaflop, by year ' s end. taking advantage of what would again be the world ' s most powerful open computer involves challenges as daunting as designing the machine itself. just as the typical motorist cannot handle a racecar and the weekend pilot cannot fly an f - 15 fighter jet, a researcher using a modern supercomputer is thrust into a world far beyond the desktop machine with which most of us are familiar. producing the quality of cutting - edge science for which the machines were designed requires the ability not only to design the calculations, but also to get information in and out without compromising the system ' s blistering speed. ultimately, the most important aspect of a simulation is not the supercomputer ' s speed, but rather the often unwieldy volume of calculation results that represents the most important aspect of a simulation. " for most of the codes i work with, the data that comes out of the simulation tells us about the science, " explains scott klasky, a computational physicist with doe ' s national center for computational sciences at ornl. " we run a simulation, analyze the results, and from that analysis we publish the findings. in effect, we have a computational laboratory that conducts a large computational experiment, along with the associated diagnostics, analysis and visualization that lead to the major scientific


get flash to fully experience pearltrees rfid chip next to a grain of rice. this chip contains a radio - frequency electromagnetic field coil that modulates an external magnetic field to transfer a coded identification number when queried by a reader device. this small type is incorporated in consumer products, and implanted in pets, for identification purposes. radio - frequency identification ( rfid ) is the wireless non - contact use of radio - frequency electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. some tags require no battery and are powered and read at short ranges via magnetic fields ( electromagnetic induction ). near - field electromagnetic ranging ( nfer ) refers to any radio technology employing the near - field properties of radio waves as a real time location system ( rtls ). [ edit ] overview near - field electromagnetic ranging is an emerging rtls technology that employs transmitter tags and one or more receiving units. operating within a half - wavelength of a receiver, transmitter tags must use relatively low frequencies ( less than 30 m hz ) to achieve significant ranging. depending on the choice of frequency, nfer has the potential for range resolution of 30 cm ( 1 ft ) and ranges up to 300 m ( 1, 000 ft ). [ 1 ] [ edit ] technical discussion real - time locating systems ( rtls ) are used to automatically identify and track the location of objects or people in real time, usually within a building or other contained area. wireless rtls tags are attached to objects or worn by people, and in most rtls, fixed reference points receive wireless signals from tags to determine their location. [ 1 ] examples of real - time locating systems include tracking automobiles through an assembly line, locating pallets of merchandise in a warehouse, or finding medical equipment in a hospital. the physical layer of rtls technology is usually some form of radio frequency ( rf ) communication, but some systems use optical ( usually infrared ) or acoustic ( usually ultrasound ) technology instead of or in addition to rf. tags and fixed reference points can be transmitters, receivers, or both, resulting in numerous possible technology combinations. scp technology makes it possible to provide reliable, consistent, and accurate indoor positioning without the support of network infrastructure and services. by exploiting freely available signals including gps, cellular, digital television, and wireless lan ( e. g. wifi ), scp based doppler aided inertial navigation ( dain ) determines location through a sensor fusion approach. combining inertial, magnetic, and gravity data with the sc


search our database of handpicked sites looking for a great physics site? we ' ve tracked down the very best and checked them for accuracy. just fill out the fields below and we ' ll do the rest. you searched for we found 10 results on physics. org and 102 results in our database of sites 102 are websites, 0 are videos, and 0 are experiments ) search results on physics. org search results from our links database description of nuclear fission with details of uranium, other isotopes and the history, good links to other sites. nuclear fission explained simply. a brief description of how nuclear fission power works from marshall brain ' s howstuffworks. com. concentrating on the fission of uranium 135. part of a nuclear reactor tour, this site gives a simplified explanation of nuclear energy. a quick introduction to nuclear energy. a brief description of how nuclear bombs work from marshall brain ' s howstuffworks. com. the pages cover the principles of fission and fusion bombs. description of nuclear binding energy with energy curve and discussion of yields from fission and fusion. an introduction to nuclear medicine, nuclear reactors, nuclear physics, nuclear power, nuclear waste and war. includes movie clips of the effects of nuclear detonation. this is a good short introduction to the topic and includes a link to listen to einstein talking about his famous equation e = mc2 a well presented and comprehensive introduction to nuclear science. nuclear structure, antimatter, decay, cosmic rays, etc. excellent graphics showing 1 - 10 of 102


navy pilots and other flight specialists soon will have a new " smart machine " installed in training simulators that learns from expert instructors to more efficiently train their students. sandia national laboratories ' aemase is being provided to the navy as a component of flight simulators. modeling and simulation tools can help researchers understand and optimize the design of lithium - ion batteries. a carbon nanotube sponge that can soak up oil in water with unparalleled efficiency has been developed with help from computational simulations performed at oak ridge national laboratory. a team of biomedical engineers and hematologists at the university of pennsylvania has made large - scale, patient - specific simulations of blood function under the flow conditions found in blood vessels, using robots to run hundreds of tests on human platelets responding to combinations of activating agents that cause clotting. 3d laser scanning technology captures comprehensive dimensional data for r & d, simulations, product testing, and quality control. analyzing and modifying design parameters early and often can help companies engineer better products. many simulations and experiments already generate petabytes of data — a single petabyte is 2, 000 times more data than you can fit on a typical laptop — and they will soon be generating exabytes. the department of energy ’ s newly established scalable data management, analysis, and visualization ( sdav ) institute is intended to help scientists deal with the deluge of data. black holes grow by sucking in gas, which forms a disc around the hole and spirals in. but this usually happens too slowly to explain the great size of black holes at the center of many galaxies, including ours. a new theory compares these giants to a wall of death, in which two motorcycles — or gas discs — crash and both quickly fall into the hole. high - gain nuclear fusion could be achieved in a preheated cylindrical container immersed in strong magnetic fields, according to a series of computer simulations performed at sandia national laboratories. the simulations show the release of output energy that was many times greater than the energy fed into the container ' s liner. a new power scheme for cardiac pacemakers turns to an unlikely source : vibrations from heartbeats themselves. engineering researchers at the university of michigan designed a device that harvests energy from the reverberation of heartbeats through the chest and converts it to electricity to run a pacemaker or an implanted defibrillator. a mysterious phenomenon detected by space probes has finally been explained, thanks to a massive computer simulation that was able to precisely align with details of spacecraft


the chest and converts it to electricity to run a pacemaker or an implanted defibrillator. a mysterious phenomenon detected by space probes has finally been explained, thanks to a massive computer simulation that was able to precisely align with details of spacecraft observations. the finding could not only solve an astrophysical puzzle, but might also lead to a better ability to predict high - energy electron streams in space that could damage satellites. researchers at north carolina state university have discovered the means by which a polymer known as pvdf, polyvinylidene fluoride, enables capacitors to store and release large amounts of energy quickly. their findings could lead to much more powerful and efficient electric cars. plant and computer scientists can now study the underground world of plants with more accuracy and clarity thanks to the adaption of x - ray micro computed tomography ( micro - ct ). the method has been used in the u. k. to examine the shape and branching patterns of roots in soil. the new technique should improve the chances of breeding better crop varieties and increasing yields. some of the recent advancements in nanotechnology depend critically on how nanoparticles move and diffuse on a surface or in a fluid under non - ideal to extreme conditions. georgia institute of technology has a team of researchers dedicated to advancing this frontier. while researchers have long known of the incredible strength of spider silk, the robust nature of the tiny filaments cannot alone explain how webs survive multiple tears and winds that exceed hurricane strength. a combination of computer simulations and new experimental observations have revealed more about the sacrificial beams and stress - dependent materials that make silk so strong. using computer simulations, a researcher has shown that an oxygen molecule is stable up to pressures of 1. 9 terapascal, which is about 19 million times higher than atmosphere pressure. the result was a complete surprise, because other simple molecules like nitrogen or hydrogen do not survive such high pressures. coinciding with a peak in solar activity, nasa goddard space flight center ’ s space weather laboratory will soon simultaneously produce as many as 100 computerized forecasts by calculating multiple possible parameters, improving our ability to predict the impact of solar storms. currently, just one set of conditions is used to anticipate solar - storm activity. conventional scientific wisdom says that the interatomic forces between ions that control high - temperature processes are insensitive to the heating of the electron " glue " that binds the ions together. in effect, traditional atomistic simulations ignore electron temperature completely. however, physicist


wisdom says that the interatomic forces between ions that control high - temperature processes are insensitive to the heating of the electron " glue " that binds the ions together. in effect, traditional atomistic simulations ignore electron temperature completely. however, physicists at the lawrence livermore national laboratory have shown how electron temperature has a surprisingly large impact on phase stability and melting in refractory transition metals. taking inspiration from the yellow fattail scorpion, which uses a bionic shield to protect itself against scratches from desert sandstorms, scientists have developed a new way to protect the moving parts of machinery from wear and tear. every year, students studying aeronautical and astronautical design brace themselves for the time - consuming process of writing their own code to optimize aerospace designs. in search of a better way, a team of engineers at the aerospace design lab at stanford university has released su2, an open - source application that models the effects of fluids moving over aerodynamic surfaces. by using a novel technique to better understand mineral growth and dissolution, researchers at oak ridge national laboratory are improving predictions of mineral reactions and laying the groundwork for applications ranging from keeping oil pipes clear to sequestering radium. civil engineers at syracuse university have developed various statistical prediction models using data obtained from the metropolitan sewer district of greater cincinnati, ohio, to generate deterioration models for wastewater pipes. the models, when adapted to a given system, is intended to facilitate a proactive approach to pipeline replacements and maintenance. for some time, researchers have explored flammable ice for low - carbon or alternative fuel or as a place to store carbon dioxide. now, a computer analysis of the ice and gas compound, known as a gas hydrate, reveals key details of its structure. the results show that hydrates can hold hydrogen at an optimal capacity of 5 weight - percent, a value that meets the goal of a u. s. department of energy standard and makes gas hydrates practical and affordable. agent - based computer models use fine - scale data from actual movements of individuals obtained by detailed video recordings, global positioning systems, or mobile phone tracking. researchers say that these tools, which can help them simulate crowd movements, could also help them model the spread of infections in mass gatherings. while physicists at the large hadron collider smash together thousands of protons and other particles to see what matter is made of, they ' re never going to hurl electrons at each other. no matter how high the energy, the little negative particles won ' t break apart. but that doesn '


nasa ' s latest rover on mars depends on a sandwich of semiconducting material that can turn heat into electricity. in the case of curiosity, the steady radioactive decay of plutonium 238 warms such thermoelectric material and turns roughly 4 percent of that heat into a steady flow of electrons. a similar radioisotope thermoelectric generator ( rtg ) on the moon ' s sea of tranquility is still working after decades, as are the rtgs in the two voyager spacecraft launched 35 years ago ; such enduring reliability is the main reason nasa employed the inefficient technology. now researchers have discovered a way to at least double the efficiency of such power generators — suggesting that thermoelectrics might find a home in applications outside of aerospace and back here on earth. the most common core of new and old thermoelectrics is a compound called lead telluride. when exposed to heat on only one side — whether it be from a radioactive isotope or another source — it will induce an electric current as long as the temperature differential is maintained. the challenge of improving thermoelectrics has been to keep heat from transferring across the material without also interfering with its ability to conduct electricity. chemist mercouri kanatzidis of northwestern university and his colleagues report in nature on september 20 that by precisely engineering the material from the atomic to the individual grain scale, the thermal conductivity of lead telluride can be impeded without affecting its electrical conductivity. the result is a material that can convert at least 8 percent of the heat into electricity — and could theoretically convert as much as 20 percent. ( scientific american is part of nature publishing group. ) the researchers first melted the lead telluride and then froze it, creating nanoscale crystalline structures out of the atoms. these precisely oriented nanostructures scatter the medium wavelength vibrations, or phonons, that carry heat while allowing electrons to pass unobstructed. but longer wavelength phonons continue to pass through as well, because their wavelengths are longer than the size of the nanostructures. so kanatzidis and his colleagues went further, grinding the nanostructured material into powder. the powder was then subjected to spark plasma sintering — squeezing the powder while also passing " a very large amount of [ electrical ] current, " in the words of kanatzidis, through it briefly — to consolidate the grains into a larger block. because the sintering occurs so


pursuing the infinite promise of the infinitesimally small imagine the economic and environmental benefits of new nanomaterials that could generate energy from waste heat typically lost by cars, electronics, power plants and factories. and consider how the economy could be transformed via yet - to - be - invented nanoscale materials with optimized electrical, magnetic, optical or thermal properties. tantalizing goals like these remain elusive. while scientists could conduct millions of possible nanoscale experiments, what they lack, in layman ' s terms, are guidelines for recipes, ingredients and preparations that would yield optimal results. that ' s where penn engineering ' s jennifer r. lukes is making her mark as a leader in atomistic computer modeling, which validates and advances the emerging principles of nanoscale science with vast quantities of data. while she specializes in thermal transport research, lukes ' computer simulations identify potentially fruitful experiments for scientists and engineers looking to exploit many different useful properties that emerge in materials 100 nanometers or smaller — literally at the scale of individual atoms. " we can model thousands of variations in experimental design and materials, like a combinatorial problem, to identify good candidate structures that are likely to obtain a desired thermal, electrical, magnetic or material strength capability, " says lukes, associate professor and graduate group chair in the department of mechanical engineering and applied mechanics. " pinpointing promising combinations of particle sizes, structures and arrangements of atoms worth developing in the lab offers experimentalists huge time and cost savings. " as she wrangles complex data from computer ' experiments ' on arcane - sounding materials such as carbon nanotubes, superlattices, nanowires, and ultra thin films, lukes envisions how insights obtained about the unique properties of nanomaterials might make a difference in the world. working with collaborators, she is exploring ways to develop metamaterials with specific electrical, magnetic, optical and thermal properties. and lukes is investigating ways to address the severe thermal issues in advanced electronics, radar, and other systems by probing, at the atomic scale, the cooling performance of tiny carbon nanotube heat sinks and boiling fluorocarbon liquids. " at the nanoscale, the physical properties of materials are no longer what they are in the textbook, " says lukes, whose approach to modeling the unique thermal properties that emerge at the nanoscale may well appear in chapters of future textbooks. lukes is mindful of her responsibility to the next generation of engineers. today, she


want to stay on top of all the space news? follow @ universetoday on twitterthe lhc or large hadron collider is the world ’ s largest particle accelerator. scheduled to be operational some time in november of 2009, the purpose of the experiments to be conducted there is aimed to answer many of the questions raised by the standard model as well as the mysteries that surround the big bang. in fact, collisions to be made in the lhc are believed sufficient to recreate the conditions that were present right after the big bang. designed and constructed by the folks at cern ( european organization for nuclear research ), the lhc crosses the borders of switzerland and france. it lies some 100 meters underground and comes around in a vast 27 kilometer circumference. although found in europe, it was borne out of the collaborative efforts of at least 10, 000 scientists and engineers from laboratories and universities around the world. to reconstruct the conditions of the big bang, two beams of hadrons ( protons or lead ions for this purpose ) will be made to circle the lhc in opposite directions until they gain sufficient energy for the collision. once that is achieved, they will be made to collide head - on and the particle fragments will be collected by detectors for analysis. as of the moment, there are six experiments intended for the lhc : alice, atlas, cms ( no, they don ’ t build websites in this project ), lhcb, totem, and lhcf. - alice or a large ion collider experiment is the experiment that will recreate the conditions of the big bang. - atlas or a toroidal lhc apparatus is designed to investigate many physical mysteries including the elusive higgs boson. - cms or compact muon solenoid has the same objectives as atlas but will be using different technical solutions. - lhcb or large hadron collider beauty will hopefully provide answers regarding the unbalanced presence of matter and antimatter despite nature ’ s general design of symmetry. right now, we are only able to see more matter than antimatter. - totem or total elastic and diffractive cross section measurement will focus on a specific selection of experiments such as measuring the size of the proton. - lhcf or large hadron collider forward will make use of forward particles created inside the lhc in order to simulate the behaviors of cosmic rays. some record breaking facts regarding the lhc, aside from it being the largest particle accelerator in


below are the first 10 and last 10 pages of uncorrected machine - read text ( when available ) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole. intended to provide our own search engines and external engines with highly rich, chapter - representative searchable text on the opening pages of each chapter. because it is uncorrected material, please consider the following text as a useful but insufficient proxy for the authoritative book pages. do not use for reproduction, copying, pasting, or reading ; exclusively for search engines. ocr for page 11 classroom assessment and the national science education standards 2 the case for strengthening assessment in the science classroom this chapter provides a rationale for this report : it presents a research base for the importance of understanding and improving the assessments that occur daily in classrooms that can directly influence learning. teachers, teacher educators, administrators, and policy makers may find this chapter particularly relevant. the goals for school science projected in the standards represent a significant shift from traditional school practice. the document presents science as something that students actively do, rather than something that is done to or for them by teachers and texts. science covers not only important facts but requires that objects and events be described carefully, that questions be asked about what is seen, that explanations of natural phenomena be constructed and tested, and that the resulting ideas be communicated to other people. it emphasizes the role of evidence in drawing conclusions. it involves making connections between students ' current understandings of natural phenomena and the knowledge accepted and valued in the scientific community. science also entails problem solving and decision making in the process of applying such knowledge to new situations and asking new questions. it is a way of knowing and thinking. if teachers can determine how well their students are meeting these new goals and students can learn how to gauge their progress, both can use this information to inform teaching and learning. by doing so, a vision for school science becomes a reality : the standards present a vision of a scientifically literate populace. they outline what students need to know, understand, and be able to do to be scientifically literate at different grade levels. they describe an educational ocr for page 12 classroom assessment and the national science education standards system in which all students demonstrate high levels of performance, in which teachers are empowered to make the decisions essential for effective learning, in which interlocking communities of teachers and students are focused on learning science, and in which supportive educational programs and systems nurture achievement. ( nrc, 1999, p.


dna sequences have been depicted in many ways. i have seen them color - coded, to highlight certain features, and jacques ninio proposed a geometric representation in which each base was shown as an arrow drawn at a particular angle to the previous one to capture the global properties of a gene in an abstract pattern. the most amusing was susmnu ohno ' s transformation of sequences into music ; he would play recordings of these little etudes during his lectures, noting which genes were mozartian and which were chopinesque. to those trying to find the true meaning of gene sequences these seemed trivial and irrelevant pursuits, but i was very impressed and thought that they could provide new insights in the field of genetics, if not into genes then at least into geneticists. it was after hearing ohno talk at a meeting in japan that i discovered that there may be a whole new way of looking at genes, and at the end of the meeting i was able to announce the birth of the new subject of zenetics. this came from a comparison of the development of our subject with that of the zen stone garden, the epitome of zen art. as is well known, japanese art does not attempt to transform nature but merely rearranges it. except for the odd buddha, there are no works of monumental sculpture in which stone is carved into representations of the world ; instead there are gardens where the arrangement of water, trees and rocks is a representation of a famous view. one then finds gardens in which the vegetation has been removed to leave a more austere and abstract representation of a generalized landscape. finally, there is a further stage where a few stones are placed on sand in carefully chosen arrangements and one comes to realize, in the true zen fashion, that here the stones mean only themselves. if this is applied to genes and sequences, as in the new field of zenetics, we can see the deep truth of the human genome - that most of the sequence means only itself. this is very different from saying that the sequences have no meaning at all. this difference can only be appreciated by the oriented mind, which is close to, but not quite the same as, the oriental mind. a few months ago i found a little book on zen and realized that i had only scratched the surface of what could be an enormous collection of new knowledge. zen buddhism is very special, in that it has discovered a new approach to gaining understanding : you can forget about microarrays, cluster analysis and the rest of it because all you need is the process


could be an enormous collection of new knowledge. zen buddhism is very special, in that it has discovered a new approach to gaining understanding : you can forget about microarrays, cluster analysis and the rest of it because all you need is the process of enlightenment. it is hard to say what this is exactly, but when it happens you will know it and that ' s that. saying that sequences mean only themselves is such a moment of enlightenment and the fact that it may be illogical only proves that it is the real truth, reached directly. this qualifies me to provide the first complete exposition of zenetics, so that others may benefit from it and enjoy the enlightenment it offers. naturally this cannot be done in just one of these columns and there will be others to follow for those who wish to become true disciples. here i can only give a brief introduction. first and foremost there is do, the way. since zen offers many possibilities, there are many ways, such as chado, the way of tea, or bushido, the way of the warrior, or kendo, the way of the sword. i thought of leaving it as do, the way, which can also be taken as the imperative in english of doing. then i thought of emphasising this as dodo, the way of doing, but that would be confusing. perhaps the best is jindo, phonetically translated as the way of the gene but more accurately as the way of the person or even the way of the inner being. now, in addition to the way, zen has three other features : the haiku, which is a poem of seventeen syllables arranged as 5 - 7 - 5, which is what can be said in one human breath ; koans, which are illogical riddles ; and the sayings of the masters. the haiku. allows us to capture an essence in one single statement, and here is an offering : on messenger rna or, a haiku that is a modification of the ancient form but still has seventeen syllables : adenine with thymine cytosine with guanine i have no space for further exposition, except for one koan. a post - doc asked the teacher " why is there the word dai in the title? " the teacher replied " because it does not mean small ".


experiment. without any preliminary, ask a number of persons kindly to draw from memory the figure which indicates six o ' clock, exactly as it appears on the dials of their watches. you will find that some of these persons will simply write the figure vi or 6 ; others, sharper, remembering that the figures take their line of direction from the centre of the dial, will write the symbol upside down, ix or 9. everybody, however, will be quite convinced that his particular testimony is correct, and ready to swear to it on oath. now ask them to take out their watches and look at them. most of them will discover to their stupefaction that the figure vi or ix which they saw so clearly at the foot of the imaginary watch floating before their mind ' s eye has no existence at all on the dial of the real watch, where its place is taken by the small seconds - hand dial! here, then, we have a great number of inaccurate depositions ; and yet, how often in the course of a day do most people look at their watches! there is no doubt, moreover, that all these people whom you have thus proved to be wrong acted in perfect good faith ; not one of them had any wilful intention of deceiving. again, it is not uncommon to find a man who has owned his watch for many years, utterly unable to state whether the hours on the dial are indicated by roman numerals or arabic figures. this means only lack of observation, but quite as common is mistaken observation. an amusing practical test of this is thus related of professor dueck. in order to test the memory and susceptibility to suggestion of his pupils he performed the following experiment on forty - eight boys between the ages of fourteen and seventeen. he passed a silver coin about the size of a fifty - cent piece around the class, instructing each boy to examine it carefully, but giving no further indications as to the purpose of his action. at the end of the lesson, which in other respects proceeded as usual, professor dueck, having again taken possession of the coin, addressed the class as follows : " you have no doubt observed that the coin which i handed around had a hole in it ; now i should like to test your powers of observation. i am, therefore, going to ask each of you to indicate the point on the coin where the hole is found. just take a piece of paper, draw a circle upon it, and indicate roughly the position of the head on the coin and


so by entangling two photons, for instance, physicists have demonstrated the ability to transmit quantum information from one place to another by encoding it in these quantum states — influence one of the pair and a change can be measured in the other without any information actually passing between the two. researchers have done this before, between photons, between ions, and even between a macroscopic object and a microscopic object. but now chinese researchers have, for the first time, achieved quantum teleportation between two macroscopic objects across nearly 500 feet using entangled photons … the two bundles of rubidium atoms that served as sender and receiver are more or less analogs for what we hope will someday be our “ quantum internet ” — a system of routers like the ones we have now that, instead of beaming information around a vast network of fiber optic wires, will send and receive information through entangled photons. so in a way, this is like a first proof of concept, evidence that the idea works at least in the lab. now all we have to do is figure out is how to build several of these in series so they can actually pass information from one to the other. to do that, we only have to somehow force these quantum states to exist for longer than the hundred microseconds or so that they last now before degrading. sounds easy enough.


by bill gates we can learn a lot about improving the 21st - century world from an icon of the industrial era : the steam engine. harnessing steam power required many innovations, as william rosen chronicles in the book " the most powerful idea in the world. " among the most important were a new way to measure the energy output of engines and a micrometer dubbed the " lord chancellor " that could gauge tiny distances. such measuring tools, mr. rosen writes, allowed inventors to see if their incremental design changes led to the improvements — such as higher power and less coal consumption — needed to build better engines. there ' s a larger lesson here : without feedback from precise measurement, mr. rosen writes, invention is " doomed to be rare and erratic. " with it, invention becomes " commonplace. " in the past year, i have been struck by how important measurement is to improving the human condition. you can achieve incredible progress if you set a clear goal and find a measure that will drive progress toward that goal — in a feedback loop similar to the one mr. rosen describes. this may seem basic, but it is amazing how often it is not done and how hard it is to get right. historically, foreign aid has been measured in terms of the total amount of money invested — and during the cold war, by whether a country stayed on our side — but not by how well it performed in actually helping people. closer to home, despite innovation in measuring teacher performance world - wide, more than 90 % of educators in the u. s. still get zero feedback on how to improve. an innovation — whether it ' s a new vaccine or an improved seed — can ' t have an impact unless it reaches the people who will benefit from it. we need innovations in measurement to find new, effective ways to deliver those tools and services to the clinics, family farms and classrooms that need them. i ' ve found many examples of how measurement is making a difference over the past year — from a school in colorado to a health post in rural ethiopia. our foundation is supporting these efforts. but we and others need to do more. as budgets tighten for governments and foundations world - wide, we all need to take the lesson of the steam engine to heart and adapt it to solving the world ' s biggest problems. one of the greatest successes in terms of using measurement to drive global change has been an agreement signed in 2000 by the united nations. the millennium development goals, supported by 189 nations, set 2015 as a deadline for making specific percentage improvements


( physorg. com ) - - the eventual failure of metals, such as the aluminum in ships and airplanes, can often be blamed on breaks, or voids, in the material ' s atomic lattice. they ' re at first invisible, only microns in size, but once enough of them link up, the metal eventually splits apart. cornell engineers, trying to better understand this process, have discovered that nanoscale voids behave differently than the larger ones that are hundreds of thousands of atoms in scale, studied through traditional physics. this insight could lead to improved ability to predict how cracks grow in metals, and how to engineer better materials. graduate student linh nguyen and derek warner, assistant professor of civil and environmental engineering, reported their findings in the journal physical review letters, jan. 20. using new atomistic simulation techniques, they concluded that the smallest voids in these materials, those having nanometer dimensions, don ' t contribute in the same way as microscale voids do in material failure at ordinary room temperatures and pressures. when metals fail, a physical phenomenon known as plasticity often occurs, permanently deforming, or changing the shape of the material. previously, it was theorized that both nanometer and microscale voids grow via plasticity as the material fails, but the new research says otherwise. " while this was something amenable to study with traditional atomistic modeling approaches, the interpretation of previous results was difficult due to a longstanding challenge of time scaling, " warner said. " we ' ve come up with a technique to better address that. " nguyen and warner ' s work is supported by the office of naval research, which has particular interest in the use of aluminum and other lightweight, durable metals in high - performance ship structures. explore further : atomic - scale investigations solve key puzzle of led efficiency


how lasers really work may 1, 2008 researchers in switzerland and the us have developed a new theoretical framework for describing a wide range of lasers — including unconventional systems called diffusive random lasers, which had hitherto defied a complete explanation. their theory could open the door for unconventional lasers to be used in a wider range of commercial applications such as document security, remote sensing, ultra - fast displays and diagnostic imaging. a conventional laser comprises an optical gain medium, such as a gas, that is sandwiched between two mirrors in an optical cavity. the gain medium is “ pumped ” using an external source of light or electric field such that most of its atoms or molecules are in higher energy excited states. when these states decay, they emit light that bounces back and forth in the cavity. this feedback stimulates the emission of similar light from other atoms in excited states. the result is a cavity filled with unidirectional light at the same wavelength, some of which is allowed to escape to form a laser beam. random multiple scattering the random laser — which does not have an optical cavity — was born in the mid - 1990s, when nabil lawandy of brown university in the us fired a laser beam at a beaker filled with dye that is normally used as a gain medium in a conventional laser. lawandy found that when tiny particles of metal were added to the beaker, the dye began to lase. the laser is random in the sense that the feedback for the photons generated in the dye is provided by the random multiple scattering of light from the particles. but exactly why this was happening was a mystery — particularly because the addition of scattering particles to a conventional dye laser was known to reduce its performance. as physicists began making random lasers utilizing different lasing media they discovered that there were actually two different kinds of random lasers. one is the localized random laser, in which light is believed to be confined to “ hot - spots " ( a situation closer to that of a conventional cavity laser ). the other is the diffusive random laser, or drl, in which the particles are not very reflective. in a drl the light effectively seeps out of the medium rapidly, instead of being confined. this rapid escape of light is very different than what occurs in an optical cavity, leaving physicists wondering how a drl could function as a laser. researchers have had some success describing a theory of localized random lasers, but an understanding of drls had been difficult to pin down. but now


than what occurs in an optical cavity, leaving physicists wondering how a drl could function as a laser. researchers have had some success describing a theory of localized random lasers, but an understanding of drls had been difficult to pin down. but now, hakan tureci of the swiss federal institute of technology in zurich and douglas stone and colleagues at yale university have come up with a new general theory of lasers that explains the operation of both types of random laser as well as more conventional lasers ( science ). the team used their theory to create computer simulations that can model the extreme leakiness of a drl and determine a number of key parameters of the laser including its output power and the wavelengths of the laser light emitted. inputs to the simulation include the distribution of scattering particles in the medium and the pumping power. their model considers all possible ways that light can reflect back and forth in the medium ( its resonant modes ) and works out how these modes interact with each other to define the wavelengths of the light that is produced by the laser. using the simulation, the team was able to reproduce a key feature of drls that had eluded previous theories – that the wavelengths of the laser light emitted are always the same, no matter how the drl is pumped. the team is currently using their theory to understand the stability of the output wavelengths. tureci is also confident that the theory will be used to boost the performance of other unconventional lasers such as those based on chaotic resonators or photonic crystal - based cavities. random lasers have already been used by nabil lawandy to create a document security system whereby a liquid containing reflective particles is “ painted ” onto a piece of paper. when the material dries, it can be made to emit laser light by firing a laser at it. the precise wavelengths of the light emitted are defined by the exact locations of all the reflective particles in the dried paint — something that is different for each daub. the result is a unique signature that cannot be reproduced. about the author hamish johnston is editor of physicsworld. com