november 30, 2012 scientists build with dna bricks researchers at harvard ' s wyss institute have coaxed single strands of dna to fit together like lego bricks and form scores of complex three - dimensional shapes, including a teeny - tiny space shuttle. the technique, described in this week ' s issue of the journal science, adds a new dimension to molecular construction and should help open the way for nanoscale medical and electronic devices. " this is a simple, versatile and robust method, " the study ' s senior author, peng yin, said in a news release. the method starts with synthetic strands of dna that take in just 32 nucleotides, or molecular bits of genetic code. these individual " bricks " are coded in a way that they fit together like lego pegs and holes to form larger shapes of a specific design. a cube built up from 1, 000 such bricks ( 10 by 10 by 10 ) measures just 25 nanometers in width. that ' s thousands of times smaller than the diameter of a single human hair. the latest research builds upon work that the wyss researchers detailed in may, which involved piecing together dna strands to create two - dimensional tiles ( including cute smiley faces ). this time around, the strands were twisted in such a way that they could be interlocked, lego - style. as any visitor to legoland knows, such structures can get incredibly complex in the hands of a skilled builder. yin and his colleagues are still learning their building techniques. fortunately, the bricks could be programmed to build themselves, with the aid of 3 - d modeling software. once the designs were set, the researchers synthesized strands with the right combinations of nucleotides — adenosine, thymine, cytosine and guanine — so that when they were mixed together in a solution, at least some of the bricks would form the desired design. to demonstrate the method, 102 different 3 - d shapes were created using a 1, 000 - brick template. posted by azra raza at 05 : 57 am | permalink


why buy that theory? what if the world is complex? here, symmetry is broken ; there, the seemingly simplest of chemical reactions, hydrogen burning to water, has a messy mechanism. the means by which one subunit of hemoglobin communicates its oxygenation to a second subunit, an essential task, resembles a rube goldberg cartoon. not to speak of the intricacies of any biological response, from the rise of blood pressure or release of adrenalin when a snake lunges at us, to returning a ping - pong serve with backspin. max perutz ' s theory of the cooperativity of oxygen uptake, the way the ribosome functions — these require complicated explanations. and yes, the inherent tinkering of evolution has made them complex. but simpler chemical reactions — a candle burning — are also intricate. as complex as the essential physics of the malleability, brittleness and hardness of metals. or the geology of hydrothermal vents. when things are complex yet understandable, human beings weave stories. we do so for several reasons : a - - > b requires no story. but a - - > b - - > c - - > d and not a - - > b - - > c ' - - > d is in itself a story. second, as psychologist jerome bruner writes, " for there to be a story, something unforeseen must happen. " in science the unforeseen lurks around the next experimental corner. stories then " domesticate unexpectedness, " to use bruner ' s phrase. storytelling seems to be ingrained in our psyche. i would claim that with our gift of spoken and written language, this is the way we wrest pleasure, psychologically, from a messy world. scientists are no exception. part of the story they tell is how they got there — the x - ray films measured over a decade, the blind alleys and false leads of a chemical synthesis. it is never easy, and serendipity substitutes for what in earlier ages would have been called the grace of god. in the end, we overcome. this appeals, and none of it takes away from the ingenuity of the creative act. in thinking about theories, storytelling has some distinct features. there is always a beginning to a theory — modeling assumptions, perhaps unexpected observations to account for. then, in a mathematically oriented theory, a kind of development section follows. something is tried ; it leads nowhere, or leaves one dissatisfied


distinct features. there is always a beginning to a theory — modeling assumptions, perhaps unexpected observations to account for. then, in a mathematically oriented theory, a kind of development section follows. something is tried ; it leads nowhere, or leaves one dissatisfied. so one essays a variation on what had been a minor theme, and — all of a sudden — it soars. resolution and coda follow. i think of the surprise that comes from doing a fourier transform, or of seeing eigenvalues popping out of nothing but an equation and boundary conditions. sadly, in the published accounts of theories, much of the narrative of the struggle for understanding is left out, because of self - censorship and the desire to show us as more rational than we were. that ' s okay ; fortunately one can still see the development sections of a theoretical symphony as one examines an ensemble of theories, created by many people, not just one, groping towards understanding. the other place where narrative is rife is in the hypothesis - forming stage of doing science. this is where the " reach of imagination " of science, as jacob bronowski referred to it, is explicit. soon you will be brought down to earth by experiment, but here the wild man in you can soar, think up any crazy scheme. and, in the way science works, if you are too blinded by your prejudices to see the faults in your theoretical fantasies, you can be sure others will. many theories are popular because they tell a rollicking good story, one that is sage in capturing the way the world works, and could be stored away to deal with the next trouble. stories can be funny ; can there be humorous theories? » post comment


an aperture synthesis telescope, like the gmrt, consists of a number of antennas located on the ground and the resolution of such a telescope is proportional to the maximum projected separation between the antennas. the locations of the antennas are usually specified in the earth - centred co - ordinate system. the earth centred frame is related to the location of the antennas on the ground by however, for the purpose of imaging, only the relative separation between the antennas is important. this separation between the antennas is usually referred to as the baseline and is measured in units of the wavelength of the incident radiation. for the purpose of the theory of synthesis imaging, the antenna positions are specified in the so called frame. the geometric relationship between this frame and the frame is shown in fig. 2. 1 and the co - ordinate transformation is given by the geometric relation between the observing plane represented by the - plane and the sky plane represented by the - plane is shown in fig. 2. 2. the - plane in the sky is parallel to the plane in which measurements are made ( the - plane ) and the separation between them is denoted by. the - axis points towards the origin of the frame given by (, ) and is parallel to the - axis. the treatment of the theory of synthesis imaging given below follows that of thompson et al. ( 1986 ) and clark ( 1999 ). let represent the electric field produced by an infinitesimal element in the sky in the direction at point in the frame ( fig. 2. 2 ). the total electric field measured at this point will be an integral of the signals from all the radiation elements and is given by the source coherence function, defined as the mutual coherence function, measured at two points and on the observing plane is defined as where is the relative delay between the signals measured at the points and respectively. in the above equation, the dependence on and is implicitly via. for a plane wavefront from a direction in the sky, where is the vector separating the two antennas. it is therefore clear that depends only on the relative separation between the antenna positions given by and and can be written as in the limit of the plane wave front approximation, the denominator in equation 2. 8 can be adequately represented by and. the phase of the mutual coherence function in equation 2. 7, for a spatially incoherent source, therefore, depends only on the relative separation between the points of measurement in the far field of the radiation. let represent the unit vector along the - axis


in equation 2. 8 corresponds to the geometrical delay corrected version of this equation. if, two versions of a time series displaced with respect to each other in time by will remain coherent. in the limit of the validity of the assumption that, in equation 2. 8 can be replaced by. this is the same as the source auto - correlation function at zero lag, ( equation 2. 6 ) and is equal to the two dimensional source surface brightness, denoted by therefore, under the approximation that : using the relation between in equation 2. 10 and the above mentioned phase rotation, equation 2. 8 can be re - written as the integrals in the above equation are over the entire sky ( limits of the integral from to ). however, the antenna primary beam limits the part of the sky from which the antenna can receive radiation to, where is the diameter of a circular aperture. assuming that the response close to the centre of the primary beam is, with an additional approximation that the field of view is small ( ), equation 2. 11 can be written as the source surface brightness is described in the - plane while and are the equivalent conjugate variables in fourier space. and can therefore be interpreted as the spatial frequencies and the visibility function as the spatial frequency spectrum of the source surface brightness distribution. synthesis radio telescopes like the gmrt measure the visibility function at several points in the frame using an array of antennas which instantaneously produce pairs of interferometers. due to the rotation of the earth, the projected separations between the antennas change as the antennas track a source in the sky. over time, each antenna pair therefore measures the visibility at several points in the frame. as a result, over time, the array of antennas partially covers the volume, up to a maximum projected antenna separation of corresponding to a spatial resolution of. also, an interferometric array does not measure for baselines smaller than a minimum value. just as the maximum baseline length for which is measured corresponds to the highest spatial resolution the telescope can provide, the smallest baseline for which is measured corresponds to largest angular scale that can be represented reliably in the final image. hence, an interferometric observation will be insensitive to scales larger than ; this problem of missing short spacing measurements is referred to as the problem of ` ` missing short spacing ' '. when imaging extended objects in the sky, like the ones imaged for this dissertation, the shortest spacing for which a reliable measurement exist has for reaching implications - missing short spacings


as the problem of ` ` missing short spacing ' '. when imaging extended objects in the sky, like the ones imaged for this dissertation, the shortest spacing for which a reliable measurement exist has for reaching implications - missing short spacings result in missing extended emission in the image. if is completely sampled, at least at the nyquist rate, it can be inverse fourier transformed to recover the source brightness distribution. with a finite number of antennas located at discrete locations on the ground, the visibility function is sampled at a discreet set of points. the observed visibility can, therefore, be thought of as the true visibility, multiplied by the sampling function given by the approximation that breaks down at low frequencies and equation 2. 11 accurately described the measured visibility function. however, this is not a fourier transform relation. techniques used to recover in such cases are described in chapter 4. in practice, is measured by a number of two element interferometers, one of which is shown in fig. 2. 3. the signal from antenna 1 lags behind the signal from the antenna 2 by a phase equal to where is the reference unit vector mentioned in the previous section. under the plane wave approximation, the signals from the two antennas can be written as the response of the interferometer to a point source of flux density, located at the phase centre ( ) is therefore antennas receive radiation from a finite part of the sky, defined by the antenna primary beam. for an extended source, within the antenna primary beam, will be an integral over the source ( integral over and ; equation 2. 12 ) and can be thought of as a superposition of plane waves from the individual infinitesimal elements constituting the extended source given by equation 2. 17. as the interferometer tracks the source in the sky, the projected separation and hence the geometrical delay changes with time. changes slowly going from to when the antennas track a source from rise to set over several hours. depends on the declination of the source and the minimum elevation limits of the antennas. over short intervals of time, changes almost linearly with time. the interferometer response to a point source ( the real and imaginary parts ) therefore varies quasi - sinusoidally over short periods of time with a frequency proportional to the separation between the antennas. this quasi - sinusoidal variation of the interferometer output, due to the changing geometrical delay, is referred to as the fringe pattern. the amplitude of this fringe pattern is directly proportional to the power emitted by the


separation between the antennas. this quasi - sinusoidal variation of the interferometer output, due to the changing geometrical delay, is referred to as the fringe pattern. the amplitude of this fringe pattern is directly proportional to the power emitted by the source in the sky. the phase of these fringes also changes sinusoidally with time with a period of 24 hours. the phase of this fringe pattern due to the geometrical delay however carries no astronomically useful information about the sky ( it only carries information about the direction in the sky being tracked ). in practice therefore, the geometrical delay is continuously compensated by introducing a time variable compensating delay in the signal from one of the antennas. this operations is referred to as delay tracking. the radio - frequency ( rf ) signals from the antenna feeds, centred at a frequency, are converted to an intermediate frequency band centred at to be transported to the correlator ( in the case of gmrt, over optical fiber cables ). the path length for the signals from the antenna to the correlator introduces a time invariant fixed delay suffered by the signals at. the compensating delay must therefore compensate for as well. for the gmrt, the compensating delay is applied to the signals at baseband frequencies in the correlator. however, the signals suffer the delays and at the rf and if frequencies respectively. delay compensation at the baseband therefore leaves a residual phase given by effectively, the phase of the visibilities is rotated by, equivalent to the residual delay due to the differences in the rf, if and base band frequencies. the phase of the visibility for a point source located at the phase centre is thus reduced to zero at all times. this final rotation of the fringe phase is referred to as fringe stopping or fringe rotation. note that the total phase applied to the visibilities via delay tracking and fringe rotation is equal to and this effectively phases the interferometer for a point in the sky ( the phase centre ). application of this total phase is achieved in the gmrt correlator in two stages, as explained in section 2. 5. 2. the response of the interferometer is integrated over the signal bandwidth as seen by the multiplier in the correlator. if represents the voltage response of the antennas as seen by the multiplier, the effect of a finite bandwidth is to modulate the output of the interferometer by the fourier transform of. if the receiver has a


ibm has successfully demonstrated a new technique for improving transistor performance, allowing it to build smaller, more powerful chips in the next decade, the company declared yesterday. ibm researcher huiling shang said the company had discovered a way to use germanium to improve the flow of electrons through its transistor. a layer of strained germanium was applied directly to the channel of the transistor, or the area through which electrical current passes, to open up additional space for electrons within the channel. according to shang, transistors built with strained germanium should have three times the performance of conventional transistors. germanium has been used in smaller doses by several companies, including ibm, in an existing manufacturing technique called strained silicon. this involves placing a mixture of germanium and silicon next to a layer of pure silicon, which causes the silicon atoms to stretch to align themselves with the silicon germanium atoms. this opens a wider path that allows more electrons to flow through the circuit. shang said researchers had long known that germanium was a better conductor of electricity than silicon, but ibm was the first to figure out how to build higher concentrations of germanium into chips using conventional techniques. she added that the company had also worked out how to strain the germanium layer to improve performance further. a by - product of zinc ore processing, germanium is a hard element with the same crystal structure as a diamond. it is a semiconductor with electrical properties between those produced by a metal and an insulator. its use as a transistor was key in the advancement of solid - state electronics. ibm will present more details on how it accomplished its feat with germanium at the 2004 international electron devices meeting in san francisco next week. the technique gives chipmakers another resource to improve performance as shrinking the transistor becomes more difficult. although the technique is still in the research stage, ibm believes it could be used on the 32 - nanometer process generation, currently scheduled for introduction around 2013. chip designers have been improving performance for years by making transistors smaller and smaller. smaller transistors are generally faster, and more of them can be fitted on a chip. but they have now become so small that electrical current can leak out of the transistors as heat, a problem that is evident at the current 90 - nanometer process generation and is expected to get worse at the 65 - nanometer process generation scheduled for introduction in 2005 and 2006. the number attached to the process generation refers to the width of the smallest circuit line within a chip. other chip


a new direction in ai - - toward a computational theory of perceptions : reflecting the bounded ability of the human brain to resolve detail, perceptions are intrinsically imprecise. in more concrete terms, perceptions are f - granular, meaning that ( 1 ) the boundaries of perceived classes are unsharp ; and ( 2 ) the values of attributes are granulated, with a granule being a clump of values ( points, objects ) drawn together by indistinguishability, similarity, proximity, and functionality. f - granularity of perceptions puts them well beyond the reach of traditional methods of analysis based on predicate logic and / or probability theory. the computational theory of perceptions ( ctp ) that is outlined here adds to the armamentarium of ai a capability to compute and reason with perception - based information. the point of departure in ctp is the assumption that perceptions are described by propositions drawn from a natural language. in ctp, a proposition, p, is viewed as an answer to a question and the meaning of p is represented as a generalized constraint. to compute with perceptions, their descriptors are translated into what is called the generalized constraint language ( gcl ). then, a goal - directed constraint propagation is employed to answer a give query. a concept that plays a key role in ctp is that of precisiated natural language ( pnl ). the computational theory of perceptions suggests a new direction in ai - - a direction that may enhance the ability of ai to deal with real - world problems in which decision - relevant information is a mixture of measurements and perceptions. what is not widely recognized is that many important problems in ai fall into this category. precisiated natural language ( pnl ) : it is a deep - seated tradition in science to view the use of natural languages in scientific theories as a manifestation of mathematical immaturity. the rationale for this tradition is that natural languages are lacking in precision. however, what is not widely recognized is that adherence to this tradition carries a steep price - - the inability to exploit the richness of natural languages in a way that lends itself to computation and automated reasoning. in a significant departure from existing methods, the high expressive power of natural languages is harnessed by a process termed precisiation. in essence, if p is proposition in a natural language ( nl ), then precisiation of p results in a representation of the meaning of p in the form of what is referred to as a generalized constraint. with these constraints serving as basic building


in essence, if p is proposition in a natural language ( nl ), then precisiation of p results in a representation of the meaning of p in the form of what is referred to as a generalized constraint. with these constraints serving as basic building blocks, composite generalized constraints can be generated by combination, constraint propagation, modification, and qualification. the set of all composite generalized constraints and associated rules of generation and interpretation constitute the generalized constraint languages ( gcl ). translation from nl to glc is governed by the constraint - centered semantics of natural languages ( csnl ). thus, through csnl, gcl serves as precisiation language for nl. precisiation natural language ( pnl ) is a subset of nl, which is equipped with constraint - centered semantics and is translatable into glc. by construction, gcl is maximally expressive. in consequence, pnl is the largest subset of nl, which admits precisiation. the expressive power of pnl is far greater than that of conventional predicate - logic - based meaning - representation languages. the concept of pnl opens the door to a significant enlargement of the role of natural languages in scientific theories and, especially, in information processing, decision, and control. in these and other realms, a particularly important function that pnl can serve is that of a concept definition language - - a language that makes it possible to formulate precise definitions of new concepts and redefine those existing concepts that do not provide a good fit to reality. perception - based decision analysis ( pda ) : decisions are based on information. more often than not, the information available is a mixture of measurements and perception. the problem with perceptions is that they are intrinsically imprecise. a concept that plays a key role in perception - based decision analysis is that of precisiated natural language, pnl. in pda, precisiated natural language is employed to define the goals, constraints, relations, and decision - relevant information. an important sublanguage of pnl is the language of fuzzy if - then rules, frl. in this language, a perception of a function, f, is described by a collection of fuzzy if - then rules. such a collection is referred to as the fuzzy graph of function f. employment of pnl in decision analysis adds an important capability - - a capability to operate on perception - based information. the capability has the effect of substantially enhancing the ability of da to deal with real - world problems. more fundamentally, the high


f. employment of pnl in decision analysis adds an important capability - - a capability to operate on perception - based information. the capability has the effect of substantially enhancing the ability of da to deal with real - world problems. more fundamentally, the high expressive power of pnl opens the door to a redefinition of such basic concepts as optimality and causality. perception - based decision analysis represents a significant change in direction in the evolution of decision analysis. as we move farther into the age of machine intelligence and automation of reasoning, the need for a shift from computing with numbers to computing with words, and from manipulation of measurements to manipulation of perceptions, will cease to be a matter of debate. from computing with numbers to computing with words to computation with perceptions - - a paradigm shift : the theory put forth in this research is focused on the development of what is referred to as the computational theory of perceptions ( ctp ) - - a theory that comprises a conceptual framework and a methodology for computing and reasoning with perceptions. the base for ctp is the methodology of computing with words ( cw ). in cw, the objects of computation are words and propositions drawn from a natural language. the point of departure in the computational theory of perceptions is the assumption that perceptions are described as propositions in a natural language. furthermore, computing and reasoning with perceptions is reduced to computing and reasoning with words. to be able to compute with perceptions it is necessary to have a means of representing their meaning in a way that lends itself to computation. conventional approaches to meaning representation cannot serve this purpose because the intrinsic imprecision of perceptions puts them well beyond the expressive power of predicate logic and related systems. in the computational theory of perceptions, representation of meaning is a preliminary to reasoning with perceptions - - a process that starts with a collection of perceptions that constitute the initial data set ( ids ) and terminates in a proposition or a collection of propositions that play the role of an answer to a query, that is, the terminal data set ( tds ). the principal aim of the computational theory of perceptions is the development of an automated capability to reason with perception - based information. existing theories do not have this capability and rely instead on conversion of perceptions into measurements - - a process that in many cases is infeasible, unrealistic, or counterproductive. in this perspective, addition of the machinery of the computational theory of perceptions to existing theories may eventually lead to theories that have a superior capability to deal with real - world problems and make it


data storage requirements are increasing dramatically and therefore much attention is being given to next - generation data storage media. however, in optical data storage devices the storage density is limited by the wavelength of light. this limitation can be avoided by an alternative data addressing mechanism using electric fields between nanoelectrodes with smaller dimensions than the wavelength of commercially available lasers. it has been shown that dna of a range of lengths can be aligned in an electric field [ 1, 2 ]. in this study we demonstrate the use of an ac electric field to address dna as a data storage technique. λ - dna, immobilised on an array of electrodes utilising its self - assembling properties, serves as a scaffold for fluorescent molecules. the dna is immobilised onto gold electrodes in a multi - step procedure ensuring a controlled surface coverage of the molecules onto specific electrodes. to minimise background fluorescence and to enable reversible stretching, the substrate surface is silanised prior to dna immobilisation. using a strong, spatially confined ac electric field ( 1mv / m, 400khz ) the dna molecules on each electrode are individually and reversibly stretched into a focused argon laser beam. the fluorophores ( yoyo1, molecular probes ) are rapidly photobleached when the power density of the beam is increased, allowing for data storage when associating a photobleached data point with a binary 1 and an intact data point with a binary 0 ( figure 1 ). the resulting pattern of high / low fluorescence intensities is read by measuring the fluorescence intensity, using the same dielectrophoretic addressing mechanism, but in conjunction with a much reduced power beam. although this concept of data storage has been demonstrated only on the micrometre scale, it is a promising candidate for miniaturisation, potentially to the molecular scale. figure 1. a pattern of selectively stretched λ - dna on an array of 4 gold electrodes. photobleaching the stretched dna in this configuration will result in a 1, 0, 1, 0 signal when reading back by sequentially stretching the dna on each electrode into a reduced power beam. the dna is being stretched in a 1 mv / m, 400 khz ac field. the electrodes are 10 μm in width and 15 μm apart. m. wasizu, and o. kurosawa, ieee t. ind. appl, 1990, 26, 1165.


light, a material emdelight® - glass is the innovative material for creative architects, interior designers and product designers. light as opposed to lighting when it ’ s light, the panels appear as high - grade, slightly translucent glass. when it ’ s dark, they transform into a source of light. without the use of filters, the self - lighting glass converts light into individual, versatile design media. - light emits from one or two opposing edges of the glass into the glass. - the glass is coated with a white or coloured screen pattern. each dot screens the emitted light according to the screen configuration. - the screen structure is calculated based on panel size and pane thickness to produce a harmonious distribution of light throughout the glass. - the panes are coated with ceramic inks. the ink is baked to create a durable coat that is scratchproof, colourfast, acid and alkaline resistant and thermally stable. - the average coverage or screen percent per pane of 12 - 15 percent largely preserves the transparent character. - glass with a low iron oxide content ( white glass ), which is especially pure and clear, is used. emdelight® - glass comes in various configurations, making it extremely versatile : - single - pane, tempered safety glass - laminated safety glass - insulated glass - flat or round shaped glass - slightly translucent plastics ( e. g. acrylic ) - 1600 mm x 3000 mm - is max. size for homogeneous illumination - pane thickness is between 8 and 15 mm - custom sizes are available ; consult factory or sales agent - reduced electricity consumption - electrically safe due to operation on safety low voltage ( max. 48 v ) - unrivalled long service life - minimum thermal stress - extremely compact dimensions mean little installation space is required


on the right, you see a picture of a surface which is starting along a bad path. light colors represent atoms in high layers ( isolated atoms and clumps we call islands ), and dark colors represent atoms in lower layers ( vacancies and pits ). most of the surface is pretty flat, but there is a big dark - grey pit! this pit represents a region of the surface which has lagged behind by a whole monolayer : pits like these will eventually lead the surface to become rough. experimentalists have various ways to test whether their surfaces are growing layer by layer ( flat ), or 3d ( rough ). one way is by using stm to directly image the layers ; another way is to scatter something off the surface and look for oscillations in the ` ` anti - phase intensity ' '. if a layer completes and forms a perfectly flat surface, you get anti - phase intensity of one ; if the surface is rough ( or flat but half - covered with a new layer ), the antiphase intensity goes to zero. the dashed line in the picture on the left shows the anti - phase intensity for our computer model. ( we ' re growing on a platiunum ( 111 ) surface at 130k at one layer per second, using kmc with emt potentials. ) it goes away quickly. the spiky, solid line is our proposed new method for growing surfaces. we suggest using pulsed sputtering. if we sputter ( remove atoms ) from the surface just after a complete layer has been laid down, the extra atoms and islands can be removed without digging new pits : this smooths the surface. the spikes show how the surface gets smoother ( bigger antiphase intensity ) each time we sputter : the smaller inset graph shows that it stays smooth even after a hundred layers ( at least on the computer! ). it also shows that a rough surface can be made smooth by using our pulsed sputtering method. it ' s important to pick the right time to sputter. the big pit in the top picture formed even though we did pulsed sputtering. our surface stayed flat for forty layers before the pit formed. can we time things so as to make layer - by - layer growth last forever? the reason that we lasted for forty layers is that small pits tend to shrink : only big pits grow. we tested this by starting with pits of various sizes, and watching them grow or shrink. averaging over many runs we get the picture on


applications of technology : - rechargeable lithium - ion batteries for hybrid / electric automobiles - consumer electronics - enhanced safety - complete overcharge / overdischarge protection - longer cycle life and battery life - automatic cell balancing for maximum efficiency - lower cost than electronic controls - improved power density berkeley lab scientists guoying chen and thomas j. richardson have invented a new type of separator membrane that prevents dangerous overcharge and overdischarge conditions in rechargeable lithium - ion batteries. this low cost separator, with electroactive polymers incorporated into a porous fiber membrane, provides electronic insulation and high ionic conduction during normal cell operation, enabling high charge and discharge rates for high power density. in overcharge and / or overdischarge situations, the membrane provides a reversible, self - actuated current shunt to prevent damage to the battery. by allowing other cells in the pack to continue charging, these separators balance the charge on each cell to extend battery life and use all of the available capacity. the threshold voltage for these membranes can also be tuned for different battery chemistries by using different electroactive polymers. batteries incorporating such membranes thus have higher rate capability, improved safety, and longer cycle life. when overcharged, battery safety issues including overheating, explosion, and fire may arise. even slight overcharging reduces a cell ’ s discharge capacity, leading to overdischarging, which increases impedance and heat generation, and decreases cell lifetime. yet common approaches to preventing overcharge / overdischarge all have drawbacks. for example, external electronic controls add substantial weight, cost, and complexity to a battery pack. shutdown separators that melt at ~ 160°c permanently disable the cell, increasing the strain on the remaining cells. redox shuttle additives have limited sustainable current densities and cell charging rates, and do not work well at the low temperatures commonly experienced by vehicles. the berkeley lab overcharge protection technology overcomes limitations observed in other approaches. caption : the lbnl - developed separator membrane provided long - term reversible overcharge protection for this lithium - ion cell, even after hundreds of continuous, full charge / discharge cycles over more than 1770 hours of operation. for more information : status : patent pending. available for licensing or collaborative research. see these other berkeley lab technologies in this field : reference number : ib - 3263


powders and causes the resulting solid to be less uniform. investigators hope to better understand this process and develop techniques that can be used to lower costs of production and create even better sintered materials. in the electromagnetic processing facility known as tempus, an experiment to further the understanding of the fundamentals of undercooling and formation of metallic glass was initiated around 10 : 00 p. m. ( cdt ) thursday. the facility uses a combination of an electromagnetic field and the microgravity environment to suspend metal alloys in a free space within a set of coils. within the coils, the suspended alloy may be melted and resolidified in an ultra - pure environment. the sample of zirconium - nickel was cycled through two stable melting and solidification runs, then became molten and contacted the side of the sample container, adhering there. the experiment run was then terminated and the sample was removed. “ before the sample stuck to the coils, we were able to get some good data, ” said the principal investigator, dr. hans fecht of the technical university in berlin, germany. the experiment team is evaluating data concerning the unexpected contact and sticking. the next tempus experiment run is scheduled for later this afternoon. before the handover from the on - board blue shift science crew to the red shift, teams on the ground determined that the apparent cause of earlier glitches with the experiment control computer system was data transmission from the droplet combustion experiment. transmission of this data was disabled and the droplet combustion team - - commanding the experiment from the ground - - resumed the combustion investigation which resulted in several “ good burns, ” according to researchers. voss and crouch handed off to mission specialist dr. donald thomas and payload specialist dr. gregory linteris around 1 : 00 a. m. ( cdt ). after his daily planning session, payload specialist dr. greg linteris began the first of several runs of the droplet combustion experiment. the experiment takes place in a specially designed enclosed chamber in which single droplets of heptane fuel can be burned in an atmosphere composed of a mixture of helium and oxygen. the droplet is formed by injecting heptane through two injectors on opposite sides of the test platform within the chamber. once the drop is formed, the injectors are retracted and the drop is then ignited by two hot - wire igniters that are brought near the droplet from opposite sides. the burning droplets observed and recorded using video cameras and high


feb. 17, 1998 eugene, ore. - - electrical engineers soon will have a new tool for use in designing electronic circuitry, including microelectronic devices such as computer chips, thanks to pioneering research by a university of oregon chemist. as reported in the dec. 19 issue of science magazine, mark lonergan has demonstrated the concept of a “ tunable diode, ” a new type of electronic device for controlling electricity. the appearance of the article in this prestigious publication comes almost exactly 50 years after the discovery of the transistor by three researchers, one of whom, the late walter brattain, earned a master ’ s degree from the university of oregon in 1926. brattain and his collaborators, john bardeen and william shockley, jointly received the 1956 nobel prize in physics. lonergan ’ s realization of the tunable diode relies on the special properties of a relatively new class of materials known as conducting polymers. presently, there is no direct analog to the tunable diode based on more conventional materials. “ the unique properties of this device hopefully will open new avenues for electrical engineers in the design of circuitry for the useful control and manipulation of electrical energy, ” lonergan says. the manipulation of energy in electrical circuits can be likened to the control of traffic on a highway system. in each case, specialized structures exert control over the system ’ s traffic. conventional diodes can be viewed as one kind of traffic control device - - essentially a one - way street for electricity. the tunable diode remains a one - way street, but it offers the added flexibility of a variable number of lanes. specific applications of the tunable diode and its unique characteristics have yet to be devised. lonergan notes, however, that “ if the concept of the tunable diode can be successfully transferred into a practical device, it may one day join the transistor, resistor and capacitor as a common component found in a myriad of new electronic devices. it is a new tool, and the advent of any new tool opens new possibilities. ” lonergan joined the uo chemistry faculty in 1996 as an assistant professor. originally from hillsboro, ore., he attended the university of oregon as an undergraduate, earning degrees in mathematics and chemistry with summa cum laude honors in 1990. other social bookmarking and sharing tools : the above story is reprinted from materials provided by university of oregon. note : materials may be edited for content and length. for further information, please contact the source cited above.


oct. 28, 2004 ann arbor, mich. - - picture a honeycomb and each compartment in the honeycomb is coated with living cells from a person ' s mouth, skin or a piece of bone. university of michigan associate professor nicholas kotov believes that one day, the cells in those honeycombs can be used to grow spare parts for our bodies, or even an entire artificial immune system in a bottle. an immune system in a bottle would allow faster and easier production of a flu vaccine, thus preventing another shortage, he said. in addition, the immune system in a bottle will give scientists clues how to design vaccines that activate an immune response to the unchanging part of a flu virus, making yearly vaccinations, quite possibly, unnecessary, kotov said. in the paper " inverted colloidal crystals as 3 - d cell scaffolds, " published last month in the journal langmuir, kotov ' s lab in the chemical engineering department and other collaborators introduced a way to build those cell - incubating honeycombs - - - called scaffolds - - - so that even though the cells occupy different compartments in the honeycomb, they share the same conditions, just as they would share the same conditions if growing in the body. collaborators on the paper include researchers from oklahoma state university, university of texas medial branch and stillwater oklahoma - based nomadics inc. kotov has appointments in the biomedical, materials science and chemical engineering departments. the research is so important that the defense advanced research projects agency ( darpa ) has funded a consortium of research institutions for $ 10 million to grow the immune system in a bottle. scientists can study the artificial immune system to see how it reacts to biological hazards and their countermeasures, and use the data to make more effective countermeasures, said jan walker, darpa spokesman. the birthplace of this artificial immune system is kotov ' s three dimensional scaffold, which is comprised of inverted colloidal crystals, also called photonic crystals. colloidal crystals are hexagonally ordered lattices of highly uniform spherical particles that are packed together. they have a wide range of diameters, from nanometers to micrometers and this versatility is critical for controlling the life cycle of cells and how they change ( i. e. differentiation ). kotov ' s team didn ' t use robotics or complicated computer set - ups to make the scaffolds. instead, they used heat and gel to make


nov. 3, 2004 scientists have made a world - first discovery which is a step towards using environmentally - friendly hydrogen to power our cars. a team from the universities of newcastle upon tyne and liverpool in the uk, who report their findings in the prestigious academic journal, science, have found a safe way of storing and releasing hydrogen to produce energy. they do this using nanoporous materials, which have tiny pores that are one hundred - thousandth ( 100, 000th ) the thickness of a sheet of paper. hydrogen has been investigated for a long time as a replacement for petrol, amid worries over the long - term availability of fossil fuels. it is also an environmentally - friendly alternative, as it produces only water rather than the ' greenhouse gas ', carbon dioxide. however, scientists and others have been baffled for a long time about how to store the substance - which is a gas and so contains less energy in a given volume than the liquid petrol - safely and efficiently. in his january 2003 state of the union address, president bush announced the hydrogen fuel initiative - " so that america can lead the world in developing clean, hydrogen - powered automobiles. " hydrogen storage technology - the ability to carry enough hydrogen on - board a vehicle to enable 300 - mile vehicle range - is critical to the success of the president ' s initiative. the uk government is also very keen to exploit the hydrogen economy. at the present time, no existing hydrogen storage technology meets the challenging performance required to make hydrogen - powered automobiles competitive with traditional vehicles. new and innovative ideas are needed. the liverpool and newcastle researchers have found a workable method of injecting the gas at high pressure into the tiny pores - of ten to the minus nine metres in size - in specially - designed materials to give a dense form of hydrogen. they then reduce the pressure within the material in order to store the captured hydrogen safely. heat can be applied to release the hydrogen as energy, on which a car could potentially run. professor mark thomas, of newcastle university ' s northern carbon research laboratories in the school of natural sciences, a member of the research team, said : " this is a proof of principle that we can trap hydrogen gas in a porous material and release it when required. however, if developed further, this method would have the potential to be applied to powering cars or any generator supplying power. although hydrogen - powered cars are likely to be decades away, our discovery brings this concept a step towards becoming reality. " now that we have a mechanism that works, we can go


mar. 12, 2013 encrypting a message with a strong code is the only safe way to keep your communications secret, but it will be obvious to anyone seeing such a message that the sender is hiding something, regardless of whether they are encrypting their emails for legitimate or illicit purposes. steganography on the other hand can hide a secret message in plain sight. often a message is secreted within the binary strings of 0s and 1s in a compressed image or music file format. prying eyes see only the original image or hear the song, whereas the recipient, knowing that a message is within uses software to extract it. nevertheless, a putative interception might still take place ; this kind of disguise also has the problem of requiring large file sizes. an alternative to such steganography would be to hide a message in plain sight within a plain text document. unfortunately, despite the much smaller file sizes that would be possible, secreting a message within normal text usually disrupts the grammar and syntax or the spelling and so immediately looks suspicious. now, an approach that is far less obvious and is tolerant of poor grammar has been developed by computer scientist abdelrahman desoky of the university of maryland in baltimore county, usa and is described in the latest issue of the international journal of security and networks. desoky suggests that instead of using a humdrum text document and modifying it in a codified way to embed a secret message, correspondents could use a joke to hide their true meaning. as such, he has developed an automatic joke generation based steganography methodology ( jokestega ) that takes advantage of recent software that can automatically write pun - type jokes using large dictionary databases. among the automatic joke generators available are : the mit project, chuck norris joke generator, jokes2000, the joke generator dot com and the online joke generator system ( pickuplinegen ). a simple example might be to hide the code word " shaking " in the following auto - joke. the original question and answer joke is " where do milk shakes come from? " and the correct answer would be " from nervous cows. " so far, so funny. but, the system can substitute the word " shaking " for " nervous " and still retain the humor so that the answer becomes " from shaking cows. " it loses some of its wit, but still makes sense and we are not all bob hopes, after all. other examples where substitutions are possible might include the equally funny : what do you get when you


elucidation and elaboration at the beginning of the workshop the fifty participants were randomly assigned to one of the six faraday lectures. these six working groups were briefly given the same four - fold assignment but no effort was made to enforce uniformity of treatment and as will be seen there are many differences in the manner of execution. - assignment 1. - to check the original biederstedt / davenport transcript for any misreadings and typographical errors and to attempt to figure out obscure words and phrases left untranscribed. these emendations have been incorporated into the final draft of the transcription. - assignment 2. - to present a brief summary of faraday ' s subtle and elegant pedagogy in so far as it can be inferred from his terse and self - addressed lecture notes. - assignment 3. - to compile a numerical listing of the extraordinary number of exp ' s or demonstrations that faraday incorporated into each lecture. this was to be done first in faraday ' s exact words followed by a brief modern interpretation or commentary. few of faraday ' s terse descriptions resisted elucidation and a surprising number of his demonstrations remain in the repertoire of today ' s teachers. - assignment 4. - to develop a performing version of each lecture for group presentation during the last week of the workshop. there were two conditions : the presentations were to be no longer than 30 - 40 minutes and they could invoke only macroscopic terms and explanations. both these conditions were occasionally violated ; the second was deemed decidedly unsporting. there is, however, much to be said in favor of making any introduction to chemistry primarily macroscopic and experimental. besides faraday rested little faith in the reality of atoms and molecules! woodrow wilson leadership program in chemistry the woodrow wilson national fellowship foundation cn 5281, princeton nj 08543 - 5281


nov 15, 2008, 10 : 03 pm group : basic member joined : jan 24, 2006 member no. : 4768 hi everyone, after being away for quite some time i have some new insights to share. thoughts & opinions on this are always welcome. can we design reality? what a strange question, but one worth considering. is it possible for us to design reality? to create an entirely different reality with its own set of rules unlike the ones of this universe? thinking about this requires that one looks at current scientific theory about the formation of the universe. aka, the big bang. now consider this question. why does reality behave in the way it does? why do things react in the way they do rather than in some other way? some people think that how atoms interact with each other has to do with the big bang. so perhaps this universe and the laws governing it, are something of random variation. meaning, if the big bang were to occur again, it could perhaps lead to an entirely different reality and cause it to work in a completely different way. hard to imagine, but of course its hard to imagine the universe as anything different than what it is now. its the only thing we ' ve ever known. so with this in mind, the universe is not something consisting of set, unmovable laws. rather it may be no different than a chemical reaction, except this reaction causes atoms to interact with each other in different ways. the idea is that under super immense force, such as the sum of the entire universe acting on itself. that the fundamental interaction between atoms can change. naturally, this is of course theory. however if this is true, then perhaps it is possible to engineer a reaction between atoms in a undefinable space, so that they interact with each other in a way that is different from how the atoms in our universe interact. just imagine the possibilities... nov 30, 2008, 12 : 46 pm group : basic member joined : feb 07, 2006 from : markham, just north of toronto, ontario, canada member no. : 4838 tl, have you heard of the book by dr. norman doidge? the letter below was published in the national post, nov. 28, 2008 brains and spirit re : the death of neurological nihilism, norman doidge, nov. 26. after reading norman doidge ' s interesting article, ( wednesday, nov. 26 ) i am moved to ask : shouldn ' t the title of his book [ the brain that changes itself ] really


by ζ ( zeta ), that characterizes the frequency response of a second order ordinary differential equation. it is particularly important in the study of control theory. it is also important in the harmonic oscillator. the damping ratio provides a mathematical means of expressing the level of damping in a system relative to critical damping. for a damped harmonic oscillator with mass m, damping coefficient c, and spring constant k, it can be defined as the ratio of the damping coefficient in the system ' s differential equation to the critical damping coefficient : where the system ' s equation of motion is and the corresponding critical damping coefficient is the damping ratio is dimensionless, being the ratio of two coefficients of identical units. this equation can be solved with the approach. where c and s are both complex constants. that approach assumes a solution that is oscillatory and / or decaying exponentially. using it in the ode gives a condition on the frequency of the damped oscillations, - undamped : is the case where corresponds to the undamped simple harmonic oscillator, and in that case the solution looks like, as expected. - underdamped : if s is a complex number, then the solution is a decaying exponential combined with an oscillatory portion that looks like. this case occurs for, and is referred to as underdamped. - overdamped : if s is a real number, then the solution is simply a decaying exponential with no oscillation. this case occurs for, and is referred to as overdamped. - critically damped : the case where is the border between the overdamped and underdamped cases, and is referred to as critically damped. this turns out to be a desirable outcome in many cases where engineering design of a damped oscillator is required ( e. g., a door closing mechanism ). q factor and decay rate the factors q, damping ratio ζ, and exponential decay rate α are related such that when a second - order system has ( that is, when the system is underdamped ), it has two complex conjugate poles that each have a real part of ; that is, the decay rate parameter represents the rate of exponential decay of the oscillations. a lower damping ratio implies a lower decay rate, and so very underdamped systems oscillate for long times. for example, a high quality tuning fork, which


4. 8 / 5 ( 10 ) | 14 classical and quantum mechanics via lie algebras apr 15, 2011 i ' d like to open a discussion thread for version 2 of the draft of my book ' ' classical and quantum mechanics via lie algebras ' ', available online at http : / / lanl. arxiv. org / abs / 0810. 1019, and for the... - more from physics forums - independent research more news stories us teen births have dropped to a record low, but the country still has one of the highest rates among developed nations, the us centers for disease control and prevention said thursday. health 43 minutes ago | not rated yet | 0 calorie information in fast food restaurants used by 40 percent of 9 - 18 year olds when making food choices a new study published online today ( thursday ) in the journal of public health has found that of young people who visited fast food or chain restaurants in the u. s. in 2010, girls and youth who were obese were more likely... health 11 hours ago | not rated yet | 0 ( healthday ) — implementation of systematic monitoring for medication adherence will allow for identification of barriers to adherence and tailoring of interventions, according to a viewpoint piece published... health 13 hours ago | not rated yet | 0 ( ap ) — the obama administration says more doctors and hospitals are embracing technology as adoption of computerized medical records reaches a " tipping point " in america. health 14 hours ago | not rated yet | 0 johns hopkins researchers report that hospitals may be reaping enormous income for patients whose hospital stays are complicated by preventable bloodstream infections contracted in their intensive care units. health 15 hours ago | not rated yet | 0 swiss scientists reveal the mechanism responsible for aging hidden deep within mitochondria — and dramatically slow it down in worms by administering antibiotics to the young. 18 hours ago | 4. 9 / 5 ( 9 ) | 1 | researchers from queen mary, university of london have led the largest sequencing study of human disease to date, investigating the genetic basis of six autoimmune diseases. 18 hours ago | 4. 7 / 5 ( 3 ) | 0 | until now, little was scientifically known about the human potential to cultivate compassion — the emotional state of caring for people who are suffering in a way that motivates altruistic behavior. 15 hours ago | 5 / 5 ( 2 ) | 2 | existing research shows that bicyclists who wear helmets have an 88 percent lower risk of


... differences of classical mechanics when learned with calc vs algebra? 15 hours ago what are the differences? every example i find usually has a derivative or integral or some kind of calculus defined concept that seems to make it... what is the distance traveled 19 hours ago a rough sketch of experiment. image : http : / / i43. tinypic. com / 14t4sk5. png the red dots represent a side view of path traveled, f is downward force... image of a convex lens cut in half horizontally 23 hours ago hello everyone, a friend of mine came up with this question in class and i really do not have a good answer. suppose you have a convex lens... ray tracing through optical system of thick lenses 23 hours ago can you advise me a free software that allow to draw rays passed throught system of thick lenses ( preferable in 3d )? - more from physics forums - classical physics more news stories parkinson ' s disease ( pd ) is a degenerative neurological disorder marked by a progressive loss of motor control. despite intensive research, there are currently no approved therapies that have been demonstrated to alter the... parkinson ' s & movement disorders may 20, 2013 | not rated yet | 0 faulty energy production in brain cells leads to disorders ranging from parkinson ' s to intellectual disability neuroscientist patrik verstreken of vib ( flanders institute for biotechnology ) and ku leuven has shown for the first time that dysfunctional mitochondria in brain cells can lead to learning disabilities. the link between... parkinson ' s & movement disorders may 17, 2013 | 4 / 5 ( 2 ) | 0 mcgill university researchers have unlocked a new door to developing drugs to slow the progression of parkinson ' s disease. collaborating teams led by dr. edward a. fon at the montreal neurological institute and hospital - the... parkinson ' s & movement disorders may 09, 2013 | 5 / 5 ( 1 ) | 0 | new research reveals that solanaceae — a flowering plant family with some species producing foods that are edible sources of nicotine — may provide a protective effect against parkinson ' s disease. the study appearing today... parkinson ' s & movement disorders may 09, 2013 | not rated yet | 0 ( medical xpress ) — researchers at the stanford university school of medicine have exposed the possible function, in the healthy brain, of a mysterious molecule that has been strongly implicated in parkinson ' s... parkinson ' s &


ubns requires a mechanism for ( 1 ) authentication of users over the network and ( 2 ) allowing server processes to change the user on whose behalf they execute. implementing the cryptographic mechanisms for user authentication as part of the application is complex and error prone, and as we showed, requires a substantial amount of code. moving the authentication and cryptographic mechanisms outside the application makes the application independent of these mechanism, and application programmers are usually not skilled in this area. moreover, the os mechanisms for change of process ownership are also dangerous as such privileges are among the strongest in a computer system, since changing a user typically allows the privileges of any user to be appropriated. and hence, programmers typically defer such considerations, ignoring them during initial design. but ubns affects the very structure of programs and when its consideration is delayed, it becomes increasingly expensive to retrofit. thus many applications will not be structured as ubns and the design will not satisfy the property of least privilege. netauth is a simple mechanism to invoke network authentication and process change - of - ownership, thus encouraging the design of ubns. it builds on the work of kerberos, ssh, and plan9 but seeks to do so with the style of mandatory access controls and to provide better information assurance. it netauth integrates public key and a fast re - authentication mechanism to achieve high performance authentications with the strongest possible properties. further increases in performance are enabled by the re - use of processes for the same user, saving system overhead. this simplifies the structure of such applications, and makes it much easier to build ubns. such an easy - to - use mechanism will encourage programmers to integrate security from the start, and thus construct more secure applications. not only do these mechanisms enable the construction of more secure services but also provide significant advantages for system administration. these mechanisms enable strong controls to be imposed on services without resorting to application specific configuration and without analyzing application code. manigandan radhakrishnan 2008 - 05 - 13


drunk scientists pour wine on superconductors and make an incredible discovery wine makes superconductors better at their jobs. and apparently, it makes some scientists better at their jobs too. superconductors behave like most metals ; they conduct electricity. they do so, however, with a twist. all metal has some resistance to the flow of electricity. but when the temperature drops, superconductors get less and less resistant ( and therefore more conductive ). when they reach very low temperatures, their resistance drops to zero. yoshihiko takano and other researchers at the national institute for materials science in japan were in the process of creating a certain kind of superconductor by putting a compound in hot water and soaking it for hours. they also soaked the compound in a mixture of water and ethanol. it appears the process was going well, because the scientists decided to have a little party. the party included sake, whisky, various wines, shochu, and beer. at a certain point, the researchers decided to try soaking the compound in the many, many liquors they had on hand and seeing how they compared to the more conventional soaking liquids. when they tested the resulting materials for superconductivity, they found that the ones soaked in commercial booze came out ahead. about 15 percent of the material became a superconductor for the water mixed with ethanol, and less for the pure water. by comparison, shochu jacked up conductivity by 23 percent and red wine managed to supercharge over 62 percent of the material. the scientists were pleased, if bemused with their results. so, a little sip of something turns out to make potential superconductors much better at their jobs. and, perhaps, scientists better at their jobs as well.


berkeley lab scientists delivered nearly 100 presentations at the american chemical society ’ s fall 2010 national meeting in boston, august 22 - 26, 2010. in the opening scene of the famous 1967 movie the graduate, benjamin braddock, at a party to celebrate his new degree, is given one word of advice for his future : “ plastics. ” were young benjamin to be receiving that advice today the word might well have been : “ batteries. ” economic forecasters say that the market for advanced batteries that can power electric, hybrid - electric and the emerging plug - in hybrid electric vehicles is going to be worth billions of dollars. based on their performances in electronics and power tools, lithium - ion batteries have the potential to be far superior to nickel - metal hydride batteries but several technological issues must be addressed before they ’ re applied to vehicles. marca doeff, a chemist with berkeley lab ’ s materials sciences division, presented a talk titled “ advanced li - ion battery cathode materials for vehicle technologies. ” she focused on the cathode as one of the most expensive components in lithium - ion batteries. “ also, ” doeff said, “ the cathode is the determinant of energy density in the cell because the capacity is typically much lower than that of the graphite anode, with which it must be matched. ” doeff and her colleagues are experimenting with various approaches for lowering the cost and improving the performance of lithium - ion cathodes. their studies include partial substitution of the expensive cobalt constituent with aluminum, titanium or iron in layered mixed transition metal oxides now used in batteries. so far they have found that a five - percent substitution of cobalt with aluminum increases cathode performance and cycle stability. substitution with small amounts of titanium also led to the formation of a high - capacity and high - rate positive electrode material, whereas substitution with iron led to lower cathode capacities and poor rate capabilities. “ our work shows that changes in electrochemical performance of the cathode depend highly on the nature of the substituting atom and its effect on the crystal structure, ” doeff said. high efficiency solar cells and other nano delights at that same graduation party today, young ben braddock might also have been told to think “ nano. ” economic forecasters foresee an even more bountiful future for nanoscale materials, particularly in solar energy and the electronics fields. “ nanoscale electronic materials : challenges and opportunities, ” was the title of a talk by ali javey, a faculty scientist in berkeley


an even more bountiful future for nanoscale materials, particularly in solar energy and the electronics fields. “ nanoscale electronic materials : challenges and opportunities, ” was the title of a talk by ali javey, a faculty scientist in berkeley lab ’ s materials sciences division. in his talk javey described a technique for engineering arrays of nanoscale pillars for a broad range of applications, including low cost, highly efficient solar cells, and artificial skin that provides prosthetic limbs with the sense of touch. “ our technique provides large - scale assembly of highly ordered and regular arrays of nanowire components on flexible substrates through a simple contact printing process, ” javey said. “ the ability to interface nanowire sensors with integrated electronics on large scales and with high uniformity presents an important advance toward the integration of nanomaterials for sensor this technology is being applied to portable electronic and wearable human interface applications, including artificial skin. the idea is that with the integration of advanced prosthetics into the brain for better control of joints, the addition of electronic skin with nanowire sensors could enable patients to regain their sense of touch. the skin might also be used in robotics, governing how much pressure a robot applies to an object. “ our mechanically flexible, artificial skin sensor provides impressive mechanical robustness and electrical properties, ” javey said. additionally, by utilizing optically active nanowire sensors, javey and his colleagues have been able to produce highly regular, single - crystalline nanopillar arrays of semiconductors on aluminum substrates that were then configured as solar cell modules. “ through experiments and modeling, we ’ ve demonstrated the that we can configure these solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency and broadband photo absorption arising from the geometric configuration of the nanopillars, ” javey said. “ this is a hugely promising to lower the cost of efficient solar cells. ” hydrogen from sunlight via qdot - seeded nanorods one word of advice that the graduate might not have been given at the party is “ hydrogen. ” while experts agree that hydrogen could command a key role in future renewable energy technologies, a relatively cheap, efficient and carbon - neutral means of producing it must first be developed. the photocatalytic production of hydrogen from water using solar energy meets all the necessary criteria but there remain many materials - related obstacles to the widespread use of this approach. berkeley lab director paul alivisatos, a chemist and leading authority on nanotechnology for energy discussed one idea for overcoming some


using solar energy meets all the necessary criteria but there remain many materials - related obstacles to the widespread use of this approach. berkeley lab director paul alivisatos, a chemist and leading authority on nanotechnology for energy discussed one idea for overcoming some of these obstacles in his talk titled “ photocatalytic hydrogen production with tunable nanorod heterostructures. ” in this talk, alivisatos described a model nanosystem in which a quantum dot seed of cadmium selenide, a hydrogen - generating catalyst, is embedded inside a platinum - tipped cadmium sulfide nanorod. “ in such structures, holes are three - dimensionally confined to the cadmium selenide, whereas the delocalized electrons are transferred to the metal tip, ” alivisatos said. “ consequently, the electrons are separated from the holes over three different components and by a tunable physical length. ” the seeded nanorod metal tip facilitates efficient long - lasting charge carrier separation and minimizes back reaction of intermediates. by tuning the nanorod heterostructure length and the seed size, alivisatos and his group are able to significantly increase hydrogen production compared to that of unseeded rods. “ we found our a multi - component nanoheterostructures to be highly active for hydrogen production, with an apparent quantum yield of 20 - percemt at 450 nanometers, ” alivisatos said. “ our systems were active under orange light illumination and demonstrated improved stability compared to seedless cadmium sulfide nanorods. ”


network and computer security tutorial version 0. 4. 0 april 16, 2001 this computer security tutorial is written based on my experiences with computer and network security along with my training and information i have read. the field of security is constantly changing so i cannot guarantee that information in this computer security tutorial will be current. this computer security tutorial will define some basic security issues and give insight into what causes security to be a constant issue. this computer security tutorial will help you decide what to protect and provide some basic information about attacks that may be made against your network, computer systems, or data. it will also provide computer and network security recommendations for you or your organization. although much useful information can be derived from this document without the reader having networking knowledge, to use this document in depth, i recommend that readers of this computer security tutorial have a fundamental knowledge about networking. the information contained in the ctdp networking guide contains the networking documentation required to understand this computer security tutorial. in this computer security tutorial, the terms computer security and network security will be used often. when the term computer security is used, it specifically refers to the security of one computer, although the overall security of each individual computer is required for network security. when the term network security is used, it refers to the security of the network in general. this includes such issues as password security, network sniffing, intrusion detection, firewalls, network structure and so forth. security violation definition computer or network security has been violated when unauthorized access by any party occurs. computer security is required because most organizations can be damaged by hostile software or intruders. there may be several forms of damage which are obviously interrelated. these include : the methods used to accomplish these unscrupulous objectives are many and varied depending on the circumstances. this guide will help administrators understand some of these methods and explain some countermeasures. computer security can be very complex and may be very confusing to many people. it can even be a controversial subject. network administrators like to believe that their network is secure and those who break into networks may like to believe that they can break into any network. i believe that overconfidence plays an important role in allowing networks to be intruded upon. there are many fallacies that network administrators may fall victim to. these fallacies may allow administrators to wrongfully believe that their network is more secure than it really is. this guide will attempt to clarify many issues related to security by doing the following : there are many different aspects to


* * exhibition at the mit museum - oct. 22 - dec. 24 2010, first floor gallery * * markus decker, dietmar offenhuber, orkan telhan ' dust serenade ' is a reenactment of an acoustic experiment done by german physicist august kundt. inspired by the chladni ' s famous sand figures visualizing sound waves in solid materials, kundt devised an experiment for visualizing longitudinal sound waves through fine lycopodium dust ; a setup that would allow him to measure the speed of sound in different gases. kundt was a strong believer in experimental methods over purely theoretical inquiry in a time when the disciplines of theoretical and experimental physics started to diverge. ' dust serenade ' intends to remind us the materiality of sound. tubes filled with scraps of words and letters - - cut - up theory - - interact with sound waves and turn into figures of dust. here, visitors can modulate the frequency of the sound emitted by moving a rod and create different harmonic sound effects. as sound waves figure, refigure, and disfigure the text, we invite visitors to rethink about the tension between their theorical knowlegde and the sensory experience. dust serenade is one of a series of interactive sound projects that enable visitors to experience the physical aspects of sound, presence, and atmosphere. works in the series have been shown at the ars electronica festival in linz, zagreb, istanbul and sao paulo. the project was funded by the council for the arts at mit and the austrian federal ministry for education, arts and culture ( bmukk )


approximates the term gross national product ( gnp - - q. v. ) used by economists in the united states and in other countries having a market economy. the soviet measure has been based on constant prices, which do not fully account for inflation, and has excluded depreciation. - " new soviet man " - a theoretical goal of several soviet regimes to transform the culturally, ethnically, and linguistically diverse peoples of the soviet union into a single soviet people, behaving according to the ideology of marxism - leninism ( q. v. ). - " new thinking " - gorbachev ' s view that international politics should be based on common moral and ethical norms rather than military force, including nuclear war ; an integral part of perestroika - nkgb ( narodnyi komissariat gosudarstvennoi - people ' s commissariat of state security. functioned in 1941 and again from 1943 to 1946. - nkvd ( narodnyi komissariat vnutrennykh del ) - people ' s commissariat of internal affairs. the commissariat that administered regular police organizations from 1917 to 1946. when the ogpu ( q. v. ) was abolished in 1934, the nkvd incorporated the security police organization until 1946. - the cpsu ' s ( q. v. ) system of appointing key personnel in the government and other important organizations, based on lists of critical positions and people in political favor. also refers to the individuals included on these lists. - a large agricultural and industrial region in the european part of the soviet union, extending approximately 2, 300 kilometers from kaliningrad in the northwest to sverdlovsk in the east with a north - south expanse of more than 1, 000 kilometers in places. the region does not have the black earth of the chernozem - novosti ( agentstvo pechati - news press agency. the news agency responsible for disseminating soviet information abroad. ( the word novost ' means news or something new. ) - nuclear war - fighting - the capability to use nuclear weapons to fight a war. - oblast ( pl., oblasts ) - a territorial and administrative subdivision in ten of the fifteen union republics ( q. v. ). directly subordinate to its union republic. see also autonomous oblast. - ( oecd ) organization for economic cooperation and development - founded by western nations in 1961 to stimulate economic progress and world trade. it also coordinated economic


a personal and mystical approach in the search for " divine truth. " sufism consists of semisecret sufi brotherhoods, each pursuing a different school or " path " of mystic discipline but having a common goal. - a member of the larger of the two great divisions of islam. the sunnis, who rejected the claim of ali ' s line, believe that they are the true followers of the sunna, the guide to proper behavior composed of the quran and hadith, the precedent of muhammad ' s words that serves as one of the sources of islamic law. in 1989 about 90 percent of the soviet union ' s muslims were - table of ranks - a system of ranks for nobles based on service to the tsar rather than on birth or seniority. created by peter the great in - the extensive, sub - arctic evergreen forest of the soviet union. the taiga, the largest of the five primary natural zones, lies south of the turdra ( q. v. ). - literally, published there ( abroad ). russian word for samizdat ( q. v. ) manuscripts surreptitiously sent abroad - tass ( telegrafnoe agentstvo sovetskogo - telegraph agency of the soviet union. the news agency that had a monopoly on collecting and distributing news within the - territorial production complex ( territorial ' no proyvodstvennyi kompleks ) - an economic entity consisting of various economically related industrial and agricultural enterprises ( q. v. ) in a particular geographic area. - time of troubles - period of civil war in muscovy between boyar ( q. v. ) factions from 1598 to 1613, with heavy polish involvement. - the movement of one ton of cargo a distance of one kilometer. ton - kilometers are computed by multiplying the weight ( in tons ) of each shipment transported by the distance hauled ( in - tons originated - the weight of freight ( in tons ) at its original point of - transmission belt - an organization, not formally part of the cpsu ( q. v. ) apparatus, used by the party to convey its party program ( q. v. ) and propaganda to the population at large, for example, soviet trade unions. - trans - siberian railway - the 7, 000 - kilometer railroad line, stretching from its western terminus at chelyabinsk on the eastern slopes of the ural mountains to vladivostok on the pacific ocean, was built between 1891 and 1916 to link the european part of russia


this dec. 5, 2012 news item on nanowerk features a seasonal approach to a study about ’ 4 - d ’ nanowires, a new type of transistor shaped like a christmas tree has arrived just in time for the holidays, but the prototype won ’ t be nestled under the tree along with the other gifts. “ it ’ s a preview of things to come in the semiconductor industry, ” said peide “ peter ” ye, a professor of electrical and computer engineering at purdue university. researchers from purdue and harvard universities created the transistor, which is made from a material that could replace silicon within a decade. each transistor contains three tiny nanowires made not of silicon, like conventional transistors, but from a material called indium - gallium - arsenide. the three nanowires are progressively smaller, yielding a tapered cross section resembling a christmas tree. sadly, purdue university ( indiana, us ) will not be releasing any images to accompany their dec. 4, 2012 news release ( which originated the news item ) about the ’ 4 - d ’ transistor until saturday, dec. 8, 2012. so here ’ s an image of a real christmas tree from the national christmas tree organization ’ s common tree characteristics webpage, the purdue university news release written by emil venere provides more detail about the work, “ a one - story house can hold so many people, but more floors, more people, and it ’ s the same thing with transistors, ” ye said. “ stacking them results in more current and much faster operation for high - speed computing. this adds a whole new dimension, so i call them 4 - d. ” the work is led by purdue doctoral student jiangjiang gu and harvard postdoctoral researcher xinwei wang. the newest generation of silicon computer chips, introduced this year, contain transistors having a vertical 3 - d structure instead of a conventional flat design. however, because silicon has a limited “ electron mobility ” – how fast electrons flow – other materials will likely be needed soon to continue advancing transistors with this 3 - d approach, ye said. indium - gallium - arsenide is among several promising semiconductors being studied to replace silicon. such semiconductors are called iii - v materials because they combine elements from the third and fifth groups of the periodic table. transistors contain critical components called gates, which enable the devices to switch on and off and to direct the flow of electrical current. smaller gates make faster


iii - v materials because they combine elements from the third and fifth groups of the periodic table. transistors contain critical components called gates, which enable the devices to switch on and off and to direct the flow of electrical current. smaller gates make faster operation possible. in today ’ s 3 - d silicon transistors, the length of these gates is about 22 nanometers, or billionths of a meter. the 3 - d design is critical because gate lengths of 22 nanometers and smaller do not work well in a flat transistor architecture. engineers are working to develop transistors that use even smaller gate lengths ; 14 nanometers are expected by 2015, and 10 nanometers by 2018. however, size reductions beyond 10 nanometers and additional performance improvements are likely not possible using silicon, meaning new materials will be needed to continue progress, ye said. creating smaller transistors also will require finding a new type of insulating, or “ dielectric ” layer that allows the gate to switch off. as gate lengths shrink smaller than 14 nanometers, the dielectric used in conventional transistors fails to perform properly and is said to “ leak ” electrical charge when the transistor is turned off. nanowires in the new transistors are coated with a different type of composite insulator, a 4 - nanometer - thick layer of lanthanum aluminate with an ultrathin, half - nanometer layer of aluminum oxide. the new ultrathin dielectric allowed researchers to create transistors made of indium - gallium - arsenide with 20 - nanometer gates, which is a milestone, ye said. this work will be presented at the 2012 international electron devices ( ieee [ institute of electrical and electronics engineers ] ) meeting in san francisco, california, dec. 10 – 12, 2012 ( as per the information on the registration page ) with the two papers written by the team will be published in the proceedings. i have a full list of the authors, from the news release, the authors of the research papers are gu [ jiangjiang gu ] ; wang [ xinwei wang ] ; purdue doctoral student h. wu ; purdue postdoctoral research associate j. shao ; purdue doctoral student a. t. neal ; michael j. manfra, purdue ’ s william f. and patty j. miller associate professor of physics ; roy gordon, harvard ’ s thomas d. cabot professor of chemistry ; and ye [ peide " peter " ye ]


us 5182793 a an apparatus and method for assisting persons in making decisions, using a computer programmed with artificial intelligence techniques. real world objects and events pertaining to a particular domain are represented in a knowledge base. best choices for solving problems are made according to the application of rules, which may be applied absolutely, comparatively, by weight, or ordered, according to methods selected by the user. the invention also permits the user to select from among various decision making strategies and permits the user to observe the effects of choices in hypothetical scenarios. 1. in a computer system having a stored system of rules and a knowledge base of facts, events, and programming, an improved method for using said computer to display a problem scenario and modify the scenario according to a best choice among alternative choices in a particular solution domain, comprising the steps of : representing a real world problem to be solved as at least one data object ; generating a problem scenario from a number of data objects, wherein said objects are arranged as a symbolic spreadsheet in which cells of said spreadsheet are frames representing said objects and their attributes and wherein said cells are linked by relationship attributes of said objects ; displaying said problem scenario to a user ; generating a pool of candidate solutions to said problem scenario ; determining a candidate selection strategy for evaluating said candidates, wherein said strategy defines a method for applying rules ; evaluating said candidates, using said candidate selection strategy to access and apply a combination of hard elimination rules, soft elimination rules, and comparison rules from a stored system of rules, to each of said candidate solutions until a best candidate is selected ; assigning a solution value representing said best candidate to variables of said problem scenario ; modifying said scenario to substitute said solution value, such that a new scenario reflecting the effects of said solution value is generated, wherein all objects having attributes affected by said solution value are modified ; and displaying said modified scenario to a user. 2. the method of claim 1, wherein said candidate generating step further comprises updating the characteristics of said candidates in accordance with predetermined data or user input. 3. the method of claim 1, wherein said strategy is selected in accordance with user input. 4. the method of claim 1, wherein said evaluating step comprises evaluating said candidates using a hierarchial method. 5. the method of claim 1, wherein said evaluating step comprises evaluating said candidates using a rule weighting method. 6. the method of claim 5, wherein said rule weighting method includes a step for short circuiting said evaluation step by determining that a current best candidate


of claim 1, wherein said evaluating step comprises evaluating said candidates using a rule weighting method. 6. the method of claim 5, wherein said rule weighting method includes a step for short circuiting said evaluation step by determining that a current best candidate cannot be surpassed. 7. the method of claim 29, wherein said rule weighting method learns best candidate selection by adjusting said rules. 8. the method of claim 1, wherein said candidate evaluating step further comprises using soft elimination rules. 9. the method of claim 1, wherein said candidate evaluating step further comprises using comparison rules. 10. the method of claim 1, wherein said candidate evaluating step further comprises using scoring rules. 11. the method of claim 1, wherein said candidate evaluating step further comprises using stop rules. 12. the method of claim 1, and further comprising the step of using said best choice in a final action. 13. the method of claim 1, wherein said candidate generating step further comprises updating the characteristics of said alternative choices in accordance with predetermined data or user input. 14. the method of claim 1, wherein said computer provides more than one method of applying said rules during said step of evaluating. this application is a continuation of application ser. no. 07 / 821, 234, filed jan. 9, 1992, now abandoned which is a continuation of application ser. no. 07 / 373, 420, filed jun. 30, 1989 now abandoned. this invention relates in general to computer processing, and in particular to an apparatus and method, using artificial intelligence programming techniques, for assisting human users in decision making. although there is no consensus on a definition of " artificial intelligence ", it is sometimes generally defined as a computer programming style in which programs operate on data according to rules to solve problems. artificial intelligence involves the use of symbolic, as opposed to numeric, representations of data. using computer processing to relate these symbolic representations is referred to as " symbolic processing ", and permits computers to represent real world objects in the form of symbols and to then develop associations between those symbols. a feature common to artificial intelligence programs is that they all involve knowledge, and must represent knowledge in a manner that can be used by a computer. specific applications of artificial intelligence, including those using symbolic processing, are associated with knowledge bases. a knowledge base for a particular application includes facts about the application and rules for applying those facts, i. e., declarative and procedural knowledge relevant to the domain. the " facts " of a knowledge base may include objects, events


bases. a knowledge base for a particular application includes facts about the application and rules for applying those facts, i. e., declarative and procedural knowledge relevant to the domain. the " facts " of a knowledge base may include objects, events, and relationships. to develop useful knowledge bases, the computer industry has recognized a need to combine efforts of both software engineers and experts in the particular domain. generally, the software engineer develops the expert system, and the domain expert provides information for the knowledge base. however, even this approach to creating knowledge bases ignores the expertise of a user, who may have his or her own skills to add to the decision making process. thus, there is a need for a knowledge - based system that permits the skills of the user to contribute to the knowledge base. one application of artificial intelligence is decision support for human users, especially in the form of modeling a particular real world or hypothetical operation. the operation ' s domain includes all objects, events, and relationships that affect behavior within the operation. yet, many existing systems are relatively inflexible, and rely on rule - based inference engines. these systems do not compare favorably to the ability of human intelligence to make decisions on what rules apply and how to apply them. there is a need for improved methods for applying rules. one aspect of the invention is an apparatus for aiding human users in making decisions relative to events in a particular domain of operations. the invention may be embodied in a computer system, which has a stored knowledge base, and in which the user interacts with a decision processor subsystem. features of the apparatus include assisting a user in choosing among alternative choices relevant to the domain. the apparatus permits the user to select from a number of types of rules and other data to develop a choice method. the apparatus also permits the user to develop a strategy that includes a set of parameter values and methods designed for a particular set of choices. the invention is implemented with programming that uses artificial intelligence techniques, including object oriented programming. for this reason, a decision processor subsystem may be sufficiently generalized such that it has modules that may be used in a number of different computer systems. thus, an aspect of the invention is a processor apparatus that is programmed to assist the user in choosing among alternative actions. another aspect of the invention is a method of programming a computer to assist a user in selecting among possible alternatives. specific features of the programming include representations of various types of data relevant to the selection process and various functions to implement the rules. the programming provides


another aspect of the invention is a method of programming a computer to assist a user in selecting among possible alternatives. specific features of the programming include representations of various types of data relevant to the selection process and various functions to implement the rules. the programming provides a number of different rules, and permits rules to be applied in varying ways. the programming also permits a multiplicity of methods for applying rules and enables the user to choose a desired method. another aspect of the invention is a method of using a computer to select a best choice among alternatives in a particular domain. features of the method include applying different rules, applying rules in different ways, selecting among a multiplicity of methods to make a choice, and adopting strategies for decision making. a further feature of the invention permits decisions to be made in the context of hypothetical scenarios. a technical advantage of the invention is that computer - aided decision making is accomplished in a manner that more nearly approximates human decision making. rules may be applied non - absolutely and comparatively. a further advantage of the invention is that it allows a person to combine his or her expertise interactively with a computer system that has artificial intelligence capabilities. a still further advantage of the invention is that it combines the ability of a computer to determine the effects of events with its ability to make choices relevant to those events. the novel features believed characteristic of the invention are set forth in the appended claims. the invention itself, however, is best understood by reference to the following description of illustrative embodiments, read in conjunction with the accompanying drawings. fig. 1 is a block diagram of a computer system in accordance with the invention. fig. 2 illustrates a method for creating a program architecture for programming a computer in accordance with the present invention. fig. 3 is a flowchart illustrating a method of computer - aided decision making in accordance with the present invention. figs. 4a and 4b are flowcharts illustrating steps that are further detail of the evaluation step of fig. 3. fig. 5 is a flowchart illustrating a method of computer - aided decision making, using a strategy generated by said computer. fig. 6 is a flowchart illustrating a learning routine used with the method of fig. 4b. fig. 7 is a flowchart illustrating a method of computer - aided decision making, using a scenario generated by said computer. fig. 1 represents an apparatus constructed in accordance with the present invention. in one embodiment, the invention is part of a computer network, which includes a host computer 10 and


computer - aided decision making, using a scenario generated by said computer. fig. 1 represents an apparatus constructed in accordance with the present invention. in one embodiment, the invention is part of a computer network, which includes a host computer 10 and a number of stations, each in communication with host 10 by means of a network communication system 15. an example of an application of the apparatus is a computer network for monitoring an airline flight operation, in which the domain of the operation includes all events affecting flight schedules. as will be explained below, the system provides real time support for enabling a user to comprehend the scope of a problem, observe the details of problem side effects, generate multiple possibilities for improving the situation, and evaluate alternatives for improvement. the use of this specific application is exemplary, and the apparatus and method of this invention could be used for any number of other applications in many diverse areas. a typical station is identified with the reference numeral 20. used in a network, each station 20 includes a terminal emulator to enable it to interact with host 10. however, it is not necessary to the invention that such a network be used, and the station may be a stand - alone processing unit. whether used as a terminal in a network or as a stand alone processing unit, station 20 has a number of components, including a transaction interface 30, a user interface 40, a knowledge base 50, and a decision processor system 60. these components deliver and receive information to and from each other by means of a bus 17 and other communication means. in addition, station 20 has other components ( not shown ) typical of a data processing terminal or stand - alone unit commonly in use. for example, memory other than that used for knowledge base 50 stores data and programming, and a timer ( not shown ) provides timing functions. transaction interface 30 permits data used by station 20 to be kept current with events that occur in the domain of the operation. thus, transaction interface 30 is in communication with host 10 as well as with knowledge base 50. of course, if station 20 is a stand - alone processing unit, transaction interface 30 will be in communication with some other input device and may be combined with user interface 40. transaction interface 30 is also in communication with decision processor system 60, so that information based on decisions made using the invention can be channeled from station 20 to another station or to an output device. the hardware associated with transaction interface 30 may be any one of a number of well - known input / output and other peripheral devices designed for the functions