27 january 2012 last updated at 05 : 00 et material graphene can distil booze, says study graphene and its derivatives display many unusual and useful properties membranes based on the " miracle material " graphene can be used to distil alcohol, according to a new study in science journal. an international team created the membrane from graphene oxide - a chemical derivative of graphene. they have shown that the membrane blocks the passage of several gases and liquids, but lets water through. this joins a long list of fascinating and unusual properties associated with graphene and its derivatives. graphene is a form of carbon. it is a flat layer of carbon atoms tightly packed into a two - dimensional honeycomb arrangement. because it is so thin, it is also practically transparent. as a conductor of electricity, it performs as well as copper ; and as a conductor of heat, it outperforms all other known materials. the unusual electronic, mechanical and chemical properties of graphene at the molecular scale promise numerous applications. continue reading the main story - graphene is a form of carbon that exists as a sheet, one atom thick - atoms are arranged into a two - dimensional honeycomb structure - identification of graphene announced in october 2004 - about 100 times stronger than steel and conducts electricity better than copper - about 1 % of graphene mixed into plastics could turn them into electrical conductors - analogous to millions of unrolled nanotubes stuck together andrei geim and konstantin novoselov from the university of manchester were awarded 2010 ' s nobel prize in physics for their discovery, outlined in a scientific paper in 2004. geim and others have now developed a laminate made from thin sheets of graphene oxide. these films were hundreds of times thinner than a human hair but remained strong, flexible and easy to handle. when a metal container was sealed with such a film, even the most sensitive equipment was unable to detect air or any other gas, including helium, leaking through. but when the researchers tried the same with water, they found that it evaporated without noticing the graphene seal. water molecules diffused through the graphene - oxide membranes with such a great speed that the evaporation rate was the same whether the container was sealed or open. ' just for a laugh ' dr rahul nair from manchester university, who led the team, commented : " graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules. he added : " if another atom or molecule tries the same trick, it


from manchester university, who led the team, commented : " graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules. he added : " if another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules. " professor geim added : " helium gas is hard to stop. it slowly leaks even through a millimetre - thick window glass but our ultra - thin films completely block it. at the same time, water evaporates through them unimpeded. materials cannot behave any stranger. " dr nair said : " just for a laugh, we sealed a bottle of vodka with our membranes and found that the distilled solution became stronger and stronger with time. neither of us drinks vodka but it was great fun to do the experiment. " despite this, the researchers do not offer any immediate ideas for applications. but professor geim commented : " the properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes, and for selective removal of water. " in another study in science journal, a different team reports the development of a membrane based on diamond - like carbon. this membrane has unique pore sizes that allow for the ultra - fast passage of oil through it. one expert said it could potentially be used for filtering toxic contaminants out of water or for purifying industrial chemicals


mathematics & physics articlesphysicists create new form of matter mit scientists have brought a supercool end to a heated race among physicists : they have become the first to create a new type of matter, a gas of atoms that shows high - temperature superfluidity. can an electron be in two places at the same time? in something akin to a double - slit experiment, scientists at the fritz haber institute of the max planck society, in co - operation with researchers from the california institute of technology in pasadena, california, have shown for the first time that electrons have characteristics of both waves and particles at the same time and in virtually the push of a button can be switched back and forth between these states. light that travels … faster than light! a team of researchers from the ecole polytechnique federale de lausanne ( epfl ) has successfully demonstrated, for the first time, that it is possible to control the speed of light – both slowing it down and speeding it up – in an optical fiber, using off - the - shelf instrumentation in normal environmental conditions. new mechanism for metallic magnetism predicting the magnetic behavior of metallic compounds is a surprisingly difficult problem for theoretical physicists. while the properties of a common refrigerator magnet are not a great mystery, certain materials exhibit magnetic properties that do not fit within existing theories of magnetism. one such material inspired a recent theoretical breakthrough by physicists at the university of california, santa cruz. of friction and ' the da vinci code ' the da vinci code, the best selling novel and soon - to - be - blockbuster film, may also be linked some day to the solving of a scientific mystery as old as leonardo da vinci himself — friction. research sheds light on ancient mystery a researcher at rochester institute of technology is unraveling a mystery surrounding easter island. william basener, assistant professor of mathematics, has created the first mathematical formula to accurately model the island ' s monumental societal collapse. algorithm for learning languages cornell university and tel aviv university researchers have developed a method for enabling a computer program to scan text in any of a number of languages, including english and chinese, and autonomously and without previous information infer the underlying rules of grammar. the rules can then be used to generate new and meaningful sentences. the method also works for such data as sheet music or protein sequences. scientists gain new insight into nanoscale optics new research from rice university has demonstrated an important analogy between electronics and optics that will enable light waves to be coupled efficiently to nanoscale structures and devices. physicists measure


as sheet music or protein sequences. scientists gain new insight into nanoscale optics new research from rice university has demonstrated an important analogy between electronics and optics that will enable light waves to be coupled efficiently to nanoscale structures and devices. physicists measure tiny force that limits how far machines can shrink university of arizona physicists have directly measured how close speeding atoms can come to a surface before the atoms ' wavelengths change. math unites the celestial and the atomic in recent years, researchers have developed astonishing new insights into a hidden unity between the motion of objects in space and that of the smallest particles. it turns out there is an almost perfect parallel between the mathematics describing celestial mechanics and the mathematics governing some aspects of atomic physics. universe evolution favored three and seven dimensions physicists who work with a concept called string theory envision our universe as an eerie place with at least nine spatial dimensions, six of them hidden from us, perhaps curled up in some way so they are undetectable. the big question is why we experience the universe in only three spatial dimensions instead of four, or six, or nine. presto! it ' s a semiconductor researchers at the university of pennsylvania may not have turned lead into gold as alchemists once sought to do, but they did turn lead and selenium nanocrystals into solids with remarkable physical properties. in the october 5 edition of physical review letters, online now, physicists hugo e. romero and marija drndic describe how they developed am artificial solid that can be transformed from an insulator to a semiconductor. brownian motion under the microscope an international group of researchers from the epfl ( ecole polytechnique federale de lausanne ), the university of texas at austin and the european molecular biology laboratory in heidelberg, germany have demonstrated that brownian motion of a single particle behaves differently than einstein postulated one century ago. new equation helps unravel behavior of turbulence to most people, turbulence is the jolt felt by jet passengers moving through a rough pocket of air. but to scientists, turbulence is the chaotic flow of a gas or liquid, in which parts of the current curl into irregular, ever smaller, tight eddies. ultrafast lasers take ' snapshots ' as atoms collide using laser pulses that last just 70 femtoseconds ( quadrillionths of a second ), physicists have observed in greater detail than ever before what happens when atoms collide. why ' filling - it - up ' takes more than ' tank capacity ' you fill up your " empty


##conds ( quadrillionths of a second ), physicists have observed in greater detail than ever before what happens when atoms collide. why ' filling - it - up ' takes more than ' tank capacity ' you fill up your " empty " fuel tank at the gas station and the pump charges you for more gallons than the tank ' s rated capacity. are you being deliberately overcharged? new approach to studying antimatter what happens when two atoms, each made up of an electron and its antimatter counterpart, called the positron, collide with each other? uc riverside physicists are able to see for the first time in the laboratory that these atoms, which are called positronium atoms and are unstable by nature, become even more unstable after the collision. the positronium atoms are seen to destroy one another, turning into gamma radiation, a powerful type of electromagnetic radiation. lightning research sparks new discovery lightning, a high - voltage discharge that strikes quickly and sometimes fatally, is very difficult to study. a new and surprising finding by florida institute of technology ' s dr. joseph dwyer and his team brings the study of lightning research into the laboratory. what does ' almost nothing ' weight? if subatomic particles had personalities, neutrinos would be the ultimate wallflowers. one of the most basic particles of matter in the universe, they ' ve been around for 14 billion years and permeate every inch of space, but they ' re so inconceivably tiny that they ' ve been called " almost nothing " and pass straight through things without a bump. mathematics : the loss of certainty " pure mathematics will remain more reliable than most other forms of knowledge, but its claim to a unique status will no longer be sustainable. " so predicts brian davies, author of the article " whither mathematics? ", which will appear in the december 2005 issue of notices of the ams.


by definition. the q - pochhammer symbol is a major building block in the construction of q - analogs ; for instance, in the theory of basic hypergeometric series, it plays the role that the ordinary pochhammer symbol plays in the theory of generalized hypergeometric series. unlike the ordinary pochhammer symbol, the q - pochhammer symbol can be extended to an infinite product : a q - series is a series in which the coefficients are functions of q, typically depending on q via q - pochhammer symbols. the finite product can be expressed in terms of the infinite product : which extends the definition to negative integers n. thus, for nonnegative n, one has the q - pochhammer symbol is the subject of a number of q - series identities, particularly the infinite series expansions which are both special cases of the q - binomial theorem : the q - pochhammer symbol is closely related to the enumerative combinatorics of partitions. the coefficient of in is the number of partitions of m into at most n parts. since, by conjugation of partitions, this is the same as the number of partitions of m into parts of size at most n, by identification of generating series we obtain the identity : as in the above section. we also have that the coefficient of in is the number of partitions of m into n or n - 1 distinct parts. by removing a triangular partition with n − 1 parts from such a partition, we are left with an arbitrary partition with at most n parts. this gives a weight - preserving bijection between the set of partitions into n or n − 1 distinct parts and the set of pairs consisting of a triangular partition having n − 1 parts and a partition with at most n parts. by identifying generating series, this leads to the identity : also described in the above section. the q - binomial theorem itself can also be handled by a slightly more involved combinatorial argument of a similar flavour. multiple arguments convention since identities involving q - pochhammer symbols so frequently involve products of many symbols, the standard convention is to write a product as a single symbol of multiple arguments : relationship to other q - functions we define the q - analog of n, also known as the q - bracket or q - number of n to be from this one can define the q - analog of the factorial, the q - factorial, as again, one recovers the usual factorial by taking the limit as


also known as the q - bracket or q - number of n to be from this one can define the q - analog of the factorial, the q - factorial, as again, one recovers the usual factorial by taking the limit as q approaches 1. this can be interpreted as the number of flags in an n - dimensional vector space over the field with q elements, and taking the limit as q goes to 1 yields the interpretation of an ordering on a set as a flag in a vector space over the field with one element. a product of negative integer q - brackets can be expressed in terms of the q - factorial as : from the q - factorials, one can move on to define the q - binomial coefficients, also known as gaussian coefficients, gaussian polynomials, or gaussian binomial coefficients : one can check that this converges to the usual gamma function as q approaches 1 from inside the unit disc.. note that for any x and for non - negative integer values of n. alternatively, this may be taken as an extension of the q - factorial function to the real number system. - george gasper and mizan rahman, basic hypergeometric series, 2nd edition, ( 2004 ), encyclopedia of mathematics and its applications, 96, cambridge university press, cambridge. isbn 0 - 521 - 83357 - 4. - roelof koekoek and rene f. swarttouw, the askey scheme of orthogonal polynomials and its q - analogues, section 0. 2. - exton, h. ( 1983 ), q - hypergeometric functions and applications, new york : halstead press, chichester : ellis horwood, 1983, isbn 0853124914, isbn 0470274530, isbn 978 - 0470274538


is another definition from the encyclopaedic dictionary of applied linguistics coherence is the quality of meaning unity and purpose perceived in discourse. it is not a property of the linguistic forms in the text and their denotations ( though these will contribute to it ), but of these cover forms and meanings interpreted by a receiver through knowledge and reasoning. as such, coherence is not an absolute quality of a text, but always relative to a particular receiver and context. a description of coherence is usually concerned with the links inferred between sentences or utterances. it is often contrasted with cohesion, which is the linguistic realization of such links ( halliday and hasan, 1976 ). 3 / a definition from the longman dictionary of language teaching & applied linguistics coherence n coherent adj the relationships which link the meanings of utterances in a discourse or of the sentences in a text. these links may be based on the speakers ’ shared knowledge. for example : a : could you give me a lift home? b : sorry, i ’ m visiting my sister. there is no grammatical or lexical link between a ’ s question and b ’ s reply ( see cohesion ) but the exchange has coherence because both a and b know that b ’ s sister lives in the opposite direction to a ’ s home. in written texts coherence refers to the way a text makes sense to the readers through the organization of its content, and the relevance and clarity of its concepts and ideas. generally a paragraph has coherence if it is a series of sentences that develop a main idea ( i. e. with a topic sentence and supporting sentences which relate to it ). ideas for teaching coherence as definition 3 points out coherence in conversational exchanges includes less explicit links but written texts do although coherence refers more to the way ideas are related to one another cohesion is generally easier to teach as it involves lexical and grammatical links but coherence tends to be more difficult and it would probably involve quite a lot of recognition and analysis work on the information structuring of the genre you are training your learners to produce. activities which might encourage recognition and awareness raising – a few ideas : - ordering paragraphs into texts or sentences into paragraphs - inserting sentences from a list of relevant / irrelevant ones into a completed or incomplete text - completing a text where first – last sentence or first – last paragraph are given - discussing how ideas in texts are connected to each other – e


philadelphia – researchers at the university of pennsylvania have devised a new method for aligning isolated single wall carbon nanotubes and, in the process, have created a new kind of material with liquid crystal - like properties, which they call nematic nanotube gels. the gels could potentially serve as sensors in complex fluids, where changes in local chemical environment, such as acidity or solvent quality, can lead to visible changes in the gel ' s shape. the researchers describe their findings in the current issue of physical review letters. single wall carbon nanotubes have astounded researchers with their remarkable strength and their ability to conduct heat and electricity. for many of their potential applications, however, these nanotubes work best when they are aligned parallel to one another, without forming aggregates or bundles. in solutions with low concentrations of single wall carbon nanotubes, the nanotubes are isotropic, or not oriented in a particular direction. if the concentration of the single wall carbon nanotubes is increased sufficiently, it becomes energetically favorable for the nanotubes to align. this is the nematic phase that many researchers have sought to create and utilize. " unfortunately, experience has shown that single wall carbon nanotubes tend to clump together or form three - dimensional networks in water at concentrations where theories otherwise predict they will form this nematic liquid crystal phase, " said arjun yodh, senior author and a professor in penn ' s department of physics and astronomy. " our gels effectively increase the concentration of isolated single wall carbon nanotubes without allowing them to bundle up or form networks. " yodh and his colleagues embedded isolated nanotubes coated by surfactant into a cross - linked polymer matrix, a gel. the volume of the gel is highly temperature dependent, and the researchers were able to compress it to a fraction of its original size by changing its temperature. the gel network prevented the close contact between parallel nanotubes that produces bundling, and its compression produced concentrations of isolated nanotubes that favor nematic alignment. the condensed gel thus creates concentrations of isolated, aligned nanotubes that cannot be achieved when they are suspended in water. like liquid crystals, the resulting nanotube gels exhibit beautiful defect patterns revealed by polarized light transmission through the sample that correspond to the particular nanotube alignments. the topology of the defects are, in turn, coupled to the mechanical strains present in the gel. the researchers are now exploring applications for both the technique and the properties of the nematic


key : " s : " = show synset ( semantic ) relations, " w : " = show word ( lexical ) relations display options for sense : ( gloss ) " an example sentence " - s : ( n ) open, clear ( a clear or unobstructed space or expanse of land or water ) " finally broke out of the forest into the open " - s : ( n ) outdoors, out - of - doors, open air, open ( where the air is unconfined ) " he wanted to get outdoors a little " ; " the concert was held in the open air " ; " camping in the open " - s : ( n ) open ( a tournament in which both professionals and amateurs may play ) - s : ( n ) open, surface ( information that has become public ) " all the reports were out in the open " ; " the facts had been brought to the surface " - s : ( v ) open, open up ( cause to open or to become open ) " mary opened the car door " - s : ( v ) open, open up ( start to operate or function or cause to start operating or functioning ) " open a business " - s : ( v ) open, open up ( become open ) " the door opened " - s : ( v ) open ( begin or set in action, of meetings, speeches, recitals, etc. ) " he opened the meeting with a long speech " - s : ( v ) unfold, spread, spread out, open ( spread out or open from a closed or folded state ) " open the map " ; " spread your arms " - s : ( v ) open, open up ( make available ) " this opens up new possibilities " - s : ( v ) open, open up ( become available ) " an opportunity opened up " - s : ( v ) open ( have an opening or passage or outlet ) " the bedrooms open into the hall " - s : ( v ) open ( make the opening move ) " kasparov opened with a standard opening " - s : ( v ) afford, open, give ( afford access to ) " the door opens to the patio " ; " the french doors give onto a terrace " - s : ( v ) open ( display the contents of a file or start an application as on a computer ) - s : ( adj ) open, unfastened ( affording unobstructed entrance and exit ; not shut or closed ) " an open door "


to recoil from trigonometry and geometry, similar triangles and tangent lines. this style of mathematics is about translating a problem into symbolic abstractions, and then performing meaningless symbolic manipulation to get an answer. regardless of how it ' s taught, most people will never be comfortable entering this level of abstraction in order to explore the problems of their lives. they may not need to. symbolic methods were invented in another era, tools intended to interface with pen and paper. we now live in an era of machines that can depict concrete visual representations of a problem, machines that can quickly iterate through enormous systems of differential equations, machines that can instantaneously draw plots for visual inspection, machines that can recalculate and redraw at the user ' s whim. why are we stuck teaching symbols? imagine : instead of writing abstract equations, we draw a model to simulate in software. instead of trying to make sense of algebraic results, we interactively explore parameter spaces using graphical visualizations. instead of getting " an answer ", we get an understanding. and instead of limiting our scope to that tiny subset of problems which can be solved analytically, we let our curiosity run wild, asking " what if " about anything we can model. such software will enable people to answer questions that affect their lives, without having to construct arcane abstractions. my hope is that this software will become as ubiquitous as the pocket calculator used to be. it will be the calculator of the next century. the math problem which enraptured the classroom above is as follows : a skateboarder holds on to the merry - go - round pictured to the right. the platform of the merry - go - round has a 7 - foot radius and makes a complete turn every 6 seconds. the skateboarder lets go at the 2 o ' clock position in the picture, at which time she is 30 feet from the padded wall. how long will it take the skateboarder to hit the wall? set aside for a moment that nobody would ever be faced with this particular problem as stated, nor care about the result. we will use the situation it describes to explore more interesting questions. but first, the conventional solution, as provided by the book. you do not need to read this — merely note how abstract, arcane, and contrived it is. the first step is to find out how far the skateboarder travels after letting go. in other words, we need to figure out the distance ab in the drawing to the


i implemented this example by " writing code ". but to be clear, i am absolutely not advocating " code " as the means for solving such problems. i envision a tool that allows people to model the situation directly and concretely, perhaps by simply drawing a picture. the examples in this essay are only meant to show what a solution might look like, not how to make it. now, let ' s make the problem more interesting. the simulation above gives a wonderfully visual interpretation of the solution. but one can ' t help but notice that there ' s not much solution to visualize — the result is just a number. this implies that the question isn ' t very interesting. an interesting problem should bring delight when the solution is revealed, like a mystery story. as with a mystery story, the delight comes from achieving an understanding. how does " 4. 72 seconds " help us understand anything about the skateboarder ' s situation? why is that number even meaningful? here ' s a characteristic that is intrinsically interesting : optimality. even when it doesn ' t objectively matter, people care about finding the fastest route home from work, or the apartment with the most square footage, or the best deal on orange juice in the grocery store. people like to optimize. so, let ' s ask this question : in order to reach the wall as quickly as possible, where should the skateboarder let go? astonishingly, the standard approach to this problem requires calculus, which few students learn and fewer use outside the classroom. optimization is one of the most important uses of mathematics — shouldn ' t even our most elementary mathematical tools support it? click to see a conventional solution. my solution to this problem is as follows. watch the plot fill in, and then try moving your mouse around the plot to see different trajectories. this solution required no changes to the model — we merely sweep one of the parameters and find the minimum. but look at the beautiful result. the result is no longer just a number — it ' s a point on a plot. and every point on that plot is tied to a visual trajectory. we have context. we aren ' t merely given the optimal angle ; we are presented with why it ' s the optimal angle, because we can see all the trajectories for all the angles. we can understand the situation. notice that if the skateboarder lets go anywhere on the left side of the carousel, she ' ll never reach the wall at all! ( this is


. no wonder people find math irrelevant! the unexpected multiple solution to this problem inspires a new problem, the most interesting one of all. in the previous two problems, the skateboarder could only bounce off the wall at very specific spots if she wanted to rejoin the carousel. can we make it easier on her? can we design a wall such that the skateboarder can let go anywhere, bounce off, and perfectly rejoin the carousel? this might be easy if we fully understood the criteria for bouncing and rejoining. but we don ' t yet — we only have hints. so let ' s allow the simulation to design the wall for us : it ' s a circle. but why? let ' s look at the three examples — the straight wall, the curvy wall, and the circular wall. what do the bounce - and - rejoin points all have in common? with a little thought, we can see that these are the points where a perpendicular line from the wall intersects the center of the carousel : because every point on the circular wall has a normal which goes through the center of the carousel, the skater can hit the circle anywhere and bounce back to the right place. the four problems above, respectively, are examples of how a simulation tool might allow people to solve problems in a way that is : concrete. modeling lets us set up and solve problems in a concrete domain, without translating to and from abstractions. keeping the solution grounded in the problem domain makes it palatable to many more people, makes it easier to reality - check, and encourages exploration of related problems. in context. simulation and visualization give us a broader understanding of the situation. simulation shows us not just the final answer, but the path taken to get there. visualization encourages us to see the solution as a point on a plot, not a number in isolation. unrestricted. simulation handles non - analytic situations with ease. the conditions of a problem do not need to be contrived or compromised for a convenient symbolic representation. generative. a simulation tool can be used for design, not merely analysis. guided by human creativity and insight, the tool can construct designs and help explore their implications. there are four critical issues that are not addressed by this essay. the tool. i am proposing a software tool that allows people to pose and explore problems directly and concretely, a tool that should become as ubiquitous as the pocket calculator. what is this tool? what would its interface look like? how could it be designed so problems can be posed


tool that allows people to pose and explore problems directly and concretely, a tool that should become as ubiquitous as the pocket calculator. what is this tool? what would its interface look like? how could it be designed so problems can be posed and solved quickly and casually? relevance. the tool and these methods should allow people to explore problems relevant to their lives. the example i followed here was almost a straw man, in that it ' s a school exercise — a problem that nobody would care to solve anyway. we need to compile a corpus of real, motivating problems — problems that people desperately want to explore, but currently cannot. universality. the example i explored here was a physics problem, which has a convenient visual representation and physically intuitive rules for evolving the system. most of the problems in people ' s lives cannot be expressed as physics problems. how can non - physical problems be modeled concretely, visually, tangibly? how can we specify the rules for iterating these systems without succumbing to abstraction? benefits of symbols. many scientific disciplines currently strike an uneasy balance between symbolic and numerical methods, aware of the pitfalls of both. the benefits of analytic methods can be : practical, such as finding with certainty all possible solutions to a problem. cognitive. some teachers claim that automated solvers can be crutches that impair students ' ability to reason. social. you can discuss or google a formula to learn from others who have navigated similar territory, but how do you look up or make reference to a plot or a process? how relevant are these analytic strengths to the sorts of problem - solving we are concerned with here, and how can a simulation tool match or make up for them? and on the other hand, how much does it matter if simulation falls short of symbolic methods in some respects? most people use no mathematical methods at all beyond arithmetic. so, any high - level mathematical tool that could gain any following could be considered a success. anything is better than nothing. but i believe that a truly revolutionary simulation tool can beat symbolic methods at their own game.


science fair project encyclopedia electrical conductivity is a measure of how well a material accommodates the transport of electric charge. its si derived unit is the siemens per metre, ( a2s3m - 3kg - 1 ) ( named after werner von siemens ). it is the ratio of the current density to the electric field strength. this applies also to the electrolytic conductivity of a fluid. conductance is an electrical phenomenon where a material contains movable particles with electric charge, which can carry electricity. when a difference of electrical potential is placed across a conductor, its movable charges flow, and an electric current appears. a conductor such as a metal has high conductivity, and an insulator like glass or a vacuum has low conductivity. a semiconductor has a conductivity that varies widely under different conditions, such as exposure of the material to electric fields or certain frequencies of light. si electricity units - electrical conduction for a discussion of the physical origin of electrical conductivity - electrical resistance - electrical resistivity for the use of conductivity measurements to record ph spectra which shows the interaction between different molecules as a function of the degree of dissociation of their functional groups, see the following external links : the contents of this article is licensed from www. wikipedia. org under the gnu free documentation license. click here to see the transparent copy and copyright details


a research team in japan claims it has demonstrated successfully in a solid - state device one of the two basic building blocks that will be needed to construct a viable quantum computer. the team has built a controlled not ( cnot ) gate, a fundamental building block for quantum computing in the same way that a nand gate is for classical computing. research into quantum computers is still in its early days and experts predict it will be at least 10 years before a viable quantum computer is developed. but if they can be developed, quantum computers hold the potential to revolutionise some aspects of computing because of their ability to calculate in a few seconds what might take a classical supercomputer millions of years to accomplish. the team reporting the breakthrough is headed by tsai jaw - shen and jointly funded by nec and japan ' s institute of physical and chemical research ( riken ). tsai said his team has successfully demonstrated a cnot gate in a two - qubit ( quantum bit ) solid - state device. the cnot gate is one of two gates used with quantum bits ( qubits ) that are the basic building blocks required for a quantum computer. the other, a one - qubit rotation gate, was demonstrated by tsai ' s team in 1999. now that both have been demonstrated, tsai says one of his goals is to combine them to create something called a universal gate which is a basic unit of a quantum computer. " another goal is to do some quantum algorithms based on this, " he said. one of the biggest tasks tsai said he faces is extending the time for which the two qubits are coupled together in a state known as quantum entanglement. in this state, which is one of several exotic properties associated with qubits and crucial to quantum computing, the two qubits act together even though they are not physically connected. tsai announced in february this year that his team has succeeded in entangling a pair of qubits. among the startling properties of qubits is that they do not just hold either binary 1 or binary 0, but can hold a superposition of the two states simultaneously. as the number of qubits grows, so does the number of distinct states which can be represented by entangled qubits. two qubits can hold four distinct states which can be processed simultaneously, three qubits can hold eight states, and so on in an exponential progression. so a system with just 10 qubits could carry out 1, 024 operations simultaneously as though it


##s can hold four distinct states which can be processed simultaneously, three qubits can hold eight states, and so on in an exponential progression. so a system with just 10 qubits could carry out 1, 024 operations simultaneously as though it were a massively parallel processing system. a 40 - qubit system could carry out one trillion simultaneous operations. a 100 - qubit system could carry out one trillion trillion simultaneous operations. that means calculations, such as working out the factors of prime numbers, which present problems for even the fastest supercomputers could be trivialised by a quantum computer. as an example, tsai estimated that using the shor algorithm to factor a 256 - bit binary number, a task that would take 10 million years using something like ibm ' s blue gene supercomputer, could be accomplished by a quantum computer in about 10 seconds. however, there are numerous hurdles which need to be overcome before anything like that becomes possible. the largest problem tsai faces at present is keeping the qubit pair in entanglement for as long as possible before decoherence sets in. " fighting the decoherence time is the largest problem, " he said. " for other problems there are some solutions and lots of possibilities but the decoherence is more difficult. " despite the hurdles, tsai ' s research is going well, said eiichi maruyama, director of the frontier research system at riken. he said its still hard to estimate when a viable quantum computer might be developed, however. " our guess is anywhere between 10 years and 100 years from now, " he said. martyn williams writes for idg news service


1. your general store of remembered information. 4. a person who destroys or ruins or lays waste to. 12. a graphical recording of the cardiac cycle produced by an electrocardiograph. 15. a river in north central switzerland that runs northeast into the rhine. 16. a piece of furniture with shelves for storing books. 17. a pass between mountain peaks. 18. a member of a nomadic people of the northern ural mountains. 20. being of the age 13 through 19. 21. the iridescent internal layer of a mollusk shell. 23. situated in a particular spot or position. 24. tag the base runner to get him out. 25. military action involving the use of electromagnetic energy to determine or exploit or reduce or prevent hostile use of the electromagnetic spectrum. 26. the blood group whose red cells carry both the a and b antigens. 27. a highly unstable radioactive element ( the heaviest of the halogen series ). 29. small arctic whale the male having a long spiral ivory tusk. 32. to an ample degree or in an ample manner. 35. lighted up by or as by fire or flame. 37. a trivalent metallic element of the rare earth group. 38. the arch of bone beneath the eye that forms the prominence of the cheek. 43. perceive sound. 44. a loloish language. 45. a silvery ductile metallic element found primarily in bauxite. 46. an organization of independent states to promote international peace and security. 47. black tropical american cuckoo. 52. used in former classifications to include all ratite bird orders. 54. of boats. 56. a public promotion of some product or service. 57. extinct flightless bird of new zealand. 60. king of denmark and norway who forced edmund ii to divide england with him. 62. resembling or characteristic of or appropriate to an elegy. 64. french writer who generalized surrealism to literature ( 1897 - 1982 ). 67. considerate and solicitous care. 68. an honorary arts degree. 71. the capital and largest city of hawaii. 73. a hard gray lustrous metallic element that is highly corrosion - resistant. 75. large burrowing rodent of south and central america. 76. inquire about. 77. the state capital of south australia. 80. a light touch or stroke. 81. the cry made by sheep. 82. south american caracara. 83. a loose sleeveless outer garment made from aba cloth. 1. an artificial source