EvaZadeh

Le proton, l’un des constituants fondamentaux de la matière,...

Thu, 22 Jul 2010 17:42:00 +0200

Le proton, l’un des constituants fondamentaux de la matière, serait plus petit que ce que l’on pensait jusqu’à présent. Tel est le résultat établi de manière expérimentale par une collaboration internationale de physiciens, à laquelle participe l’équipe Métrologie des Systèmes Simples et Tests Fondamentaux Laboratoire Kastler Brossel. Obtenue avec une extrême précision, cette nouvelle mesure du rayon du proton pourrait remettre en cause certaines prédictions de l’électrodynamique quantique, l’une des théories fondamentales de la physique quantique, ou bien la valeur de la constante de Rydberg (constante physique la plus précise à ce jour). Illustrations Diane DuFour, Chris Gash.

Bruno Giros, directeur de recherche au CNRS, dirige le...

Thu, 22 Jul 2010 17:38:00 +0200

Bruno Giros, directeur de recherche au CNRS, dirige le laboratoire de physiopathologie des maladies du système nerveux central, laboratoire mixte entre le CNRS, l’INSERM et l’UPMC.
Au sein de ce laboratoire, Catalina Betancur, chercheur INSERM, dirige l’équipe Génétique de l’Autisme dont l’objectif est d’identifier des gènes impliqués dans l’autisme et les troubles apparentés.

Merci à Marion PILORGE, étudiante en thèse et co-auteur de l’article publié dans la revue Nature.

"And for the first time in my life, the following afternoon, I went to the West."

Mon, 14 Jun 2010 21:32:53 +0200

“And for the first time in my life, the following afternoon, I went to the West.”

- “On the Road,” by Jack Kerouac

http://www.youdrive.org

Mon, 14 Jun 2010 12:59:41 +0200

http://www.youdrive.org

I.R.R.M. LeBlog

Mon, 12 Apr 2010 00:00:00 +0200

I.R.R.M., ou les “Introspections Radiophoniques d’un Rat en quête de Mégaphone”.

C’est une série radiophonique et scientifique dans laquelle le personnage principal, un rat de laboratoire, veut apprendre et comprendre le fonctionnement du cerveau humain.

Issu d’une lignée de 123 générations de rat albinos, Jean-Luc, vit au centre intergalactique de la recherche sur le cerveau. Il y mange bien. Sa cage est confortable. Mais quand sa mère décède des suites de manipulations extravagantes d’un jeune stagiaire, Jean-Luc décide de sortir. Depuis ce jour, il se ballade dans les conduits d’aération du centre, aux premières loges des travaux spectaculaires de grands scientifiques à la recherche de son “expérience Mégaphone” qui fera éclater sa vérité.

An interview on the road from Boston, MA to San-Francisco,...

Fri, 15 Jan 2010 04:33:00 +0100

An interview on the road from Boston, MA to San-Francisco, CA.

We randomly met Larry in Detroit. He is the owner of the Car Wash Cafe there.

Introducing Dennis, Empire Chrome Shope - West Memphis, AR.

Thu, 14 Jan 2010 02:03:00 +0100

Introducing Dennis, Empire Chrome Shope - West Memphis, AR.

"Pour vivre centenaire, il faut un bon cerveau"

Wed, 15 Apr 2009 05:14:00 +0200

“Pour vivre centenaire, il faut un bon cerveau”

- Ce sont les propos de Françoise Forette, professeur de gériatrie à l’université Paris-V et directrice de la Fondation nationale de gérontologie, relevés par Anne Jouan, journaliste au Figaro. Dans un article publié en ligne le 16 Avril 2009, la journaliste explore de nouvelles recettes pour devenir centenaires.

Je me suis vue sourire en lisant cette citation: “pour vivre centenaire, il faut un bon cerveau!” Mais bon comment? L’article ouvre néanmoins sur un domaine de recherche extrêmement pertinent: le pouvoir de notre psychisme sur notre espérance de vie.

brain on a chip ?

Fri, 20 Mar 2009 04:11:00 +0100

How does the human brain run itself without any software? Find that out, say European researchers, and a whole new field of neural computing will open up. A prototype “brain on a chip” is already working. “We know that the brain has amazing computational capabilities,” remarks Karlheinz Meier, a physicist at Heidelberg University. “Clearly there is something to learn from biology. I believe that the systems we are going to develop could form part of a new revolution in information technology.”

It’s a strong claim, but Meier is coordinating the EU-supported FACETS project which brings together scientists from 15 institutions in seven countries to do just that. Inspired by research in neuroscience, they are building a ‘neural’ computer that will work just like the brain but on a much smaller scale.

The human brain is often likened to a computer, but it differs from everyday computers in three important ways: it consumes very little power, it works well even if components fail, and it seems to work without any software.

How does it do that? Nobody yet knows, but a team within FACETS is completing an exhaustive study of brain cells - neurons - to find out exactly how they work, how they connect to each other and how the network can ‘learn’ to do new things.

Mapping brain cells “We are now in a situation like molecular biology was a few years ago when people started to map the human genome and make the data available,” Meier says. “Our colleagues are recording data from neural tissues describing the neurons and synapses and their connectivity. This is being done almost on an industrial scale, recording data from many, many neural cells and putting them in databases.”

Meanwhile, another FACETS group is developing simplified mathematical models that will accurately describe the complex behaviour that is being uncovered. Although the neurons could be modelled in detail, they would be far too complicated to implement either in software or hardware.

The goal is to use these models to build a ‘neural computer’ which emulates the brain. The first effort is a network of 300 neurons and half a million synapses on a single chip. The team used analogue electronics to represent the neurons and digital electronics to represent communications between them. It’s a unique combination.

Since the neurons are so small, the system runs 100,000 times faster than the biological equivalent and 10 million times faster than a software simulation. “We can simulate a day in one second,” Meier notes.

The network is already being used by FACETS researchers to do experiments over the internet without needing to travel to Heidelberg.

New type of computing But this ‘stage 1’ network was designed before the results came in from the mapping and modelling work. Now the team are working on stage 2, a network of 200,000 neurons and 50 million synapses that will incorporate all the neuroscience discoveries made so far.

To build it, the team is creating its network on a single 20cm silicon disk, a ‘wafer’, of the type normally used to mass-produce chips before they are cut out of the wafer and packaged. This approach will make for a more compact device.

So called ‘wafer-scale integration’ has not been used much before for this, as such a large circuit will certainly have manufacturing flaws. “Our chips will have faults but they are each likely to affect only a single synapse or a single connection in the network,” Meier points out. “We can easily live with that. So we exploit the fault tolerance and use the entire wafer as a neural network.”

How could we use a neural computer ? Meier stresses that digital computers are built on principles that simply do not apply to devices modelled on the brain. To make them work requires a completely new theory of computing. Yet another FACETS group is already on the case. “Once you understand the basic principles you may hope to develop the hardware further, because biology has not necessarily found the best solution.”

Beyond the brain? Practical neural computers could be only five years away. “The first step could be a little add-on to your computer at home, a device to handle very complex input data and to provide a simple decision,” Meier says. “A typical thing could be an internet search.”

In the longer term, he sees applications for neural computers wherever there are complex and difficult decisions to be made. Companies could use them, for example, to explore the consequences of critical business decisions before they are taken. In today’s gloomy economic climate, many companies will wish they already had one!

The FACETS project, which is supported by the EU’s Sixth Framework Programme for research, is due to end in August 2009 but the partners have agreed to continue working together for another year. They eventually hope to secure a follow-on project with support from both the European Commission and national agencies.

Meanwhile, the consortium has just obtained funding from the EU’s Marie Curie initiative to set up a four-year Initial Training Network to train PhD students in the interdisciplinary skills needed for research in this area.

Where could this go? Meier points out that neural computing, with its low-power demands and tolerance of faults, may make it possible to reduce components to molecular size. “We may then be able to make computing devices which are radically different and have amazing performance which, at some point, may approach the performance of the human brain - or even go beyond it!”

Media note: This feature can be republished without charge provided ICT Results is acknowledged as the source at the top or the bottom of the story. You must request permission before you use any of the photographs on the site. If you do republish, we would be grateful if you could link back to the ICT Results site (http://cordis.europa.eu/ictresults). Let us know if you republish so as to help us provide you with a better service. If you want further contact information on any of the projects cited in this story please contact us at ictresults@esn.eu.

Illusion d'optique... mais pas pour les patients schizophrènes

Sun, 08 Mar 2009 00:00:00 +0100

Illusion d'optique... mais pas pour les patients schizophrènes

Mon fiancé est persuadé que son iPhone est l’extension de son...

Fri, 06 Mar 2009 05:14:00 +0100

Mon fiancé est persuadé que son iPhone est l’extension de son cerveau, et que l’objet viendra un jour à disparaître pour prendre place sous sa boite crânienne.

Des chercheurs du MIT MediaLab vont dans ce sens. Ils ont eux intégré Internet au bout des doigts, pour que la navigation en ligne devienne un de vos sens.

L'outil d'analyse de votre consommation électrique

Fri, 06 Mar 2009 04:53:00 +0100

L’incontournable moteur de recherche Google a présenté il y a 15 jours PowerMeter une nouveauté issue de ses “laboratoires”. Son objectif : lutter contre le réchauffement de la planète en aidant les gens à réduire leur consommation d’électricité.

Sous la forme d’un widget, un tableau de bord permet de visualiser en temps réel sur un ordinateur la quantité d’électricité consommée dans la maison. En plus de servir de compteur électrique virtuel, le logiciel analyse la consommation et émet des suggestions pour la faire diminuer. Enfin, pour vérifier si votre voisin fait mieux que vous, il est capable comparer votre consommation avec la sienne. Concrètement, pour obtenir des informations en temps réel et pouvoir les traiter, ce logiciel ne peut fonctionner qu’en liaison avec un compteur électrique ou un appareillage spécifique. C’est pourquoi la firme de Mountain View est actuellement en pourparlers avec les compagnies d’électricité, que ce soit aux Etats-Unis, en Europe et en Asie.

L’outil est actuellement testé par les employés de la firme, mais Dan Reicher, directeur de recherche chez Google, a confirmé à Reuters que ce logiciel serait bientt disponible pour le plus grand nombre.

Vidéo de présentation (en anglais)

Seine-Saint-Denis Style

Thu, 18 Sep 2008 00:00:00 +0200

Seine-Saint-Denis Style

Photographer Amanda Means gave a public talk at the Harvard...

Fri, 16 May 2008 00:00:00 +0200

Photographer Amanda Means gave a public talk at the Harvard Museum of Natural History to explain her work.

What do plastic tubes, strings and tin cans have in common?...

Sun, 11 May 2008 00:00:00 +0200

What do plastic tubes, strings and tin cans have in common? According to Chris and Meredith Thompson, they can all be musical instruments! At the 2008 Cambridge Science Festival, the Thompson twins show an audience of kids how fun the science of sound can be.

Link

Engineers at the Harvard Microrobotics lab use insects as...

Thu, 01 May 2008 00:00:00 +0200

Engineers at the Harvard Microrobotics lab use insects as inspiration to build tiny robots that could one day help emergency rescue teams on the field.

Dr. Walter Lewin, an award-winning science educator and physics...

Thu, 06 Mar 2008 00:00:00 +0100

Dr. Walter Lewin, an award-winning science educator and physics professor at MIT, demonstrates the key to a successful science lesson.

Interview and video by Nuño Dominguez and Eva Zadeh.

Classroom footage provided by MIT.

SuperCool World

Fri, 21 Dec 2007 02:32:00 +0100

Imagine a world where you could defy any laws of physics, from gravitation to electromagnetism. Not a world of superheroes in comic books, but a world where liquids and solids would become super-cool matter.

In this world you would plug magnets under your feet and levitate to go to work. Electrical wires would never get hot and any liquid would squeeze through impossibly small holes. Spinning your glass of wine at a Friday night party would have it mimic a Swiss cheese pattern. Instead of seeing a single whirlpool at the center of your glass, you would observe a multiple of tiny vortices. Public parks would host water fountains spouting upward under the simple action of a light beam. You would have to watch after your coffee to make sure it doesn’t flow out of your cup by itself. And passing through walls to go from one room to another would just be routine.

Unfortunately, the doors for this super-cool world will not open to you. You could never survive there, because temperatures flirt with -460°F and its inhabitants’ size doesn’t surpass the thickness of a human hair.

Physicists who study condensed matter and ultra-cold atoms deal with those phenomena everyday in their labs. They know that super-fluidity and superconductivity are the intrinsic properties responsible for those strange behaviors, but they still struggle to explain all their mysteries. Today, the existence of a super-solid – a crystal that yet retains the essential properties of a solid but that could flow just like a liquid – generates animated controversy among physicists. However, unexplained properties haven’t prevented new ideas for applications to raise and get tested. Who knows? The super-cool world might become more and more important to us.

Super-cool matter showed up in experiments before it got theoretically understood. In 1911, Dutch physicist Heike Kamerlingh-Onnes observed that mercury loses any electrical resistance, hence becomes superconductive, when brought near -460°F. In 1938, Russian physicist Pjotr Kapitsa found that liquid helium suddenly lost any viscosity when cooled below a temperature of about -456°F, and called it a super-fluid. When super-fluidity strictly appears at dramatically low temperatures, superconductivity revealed itself more than 50 years later in a ceramic material at a higher temperature of -395°F. Since then, physicists have been trying to push up the temperatures of superconductors to bring them to “normal” temperatures. But today, the highest superconductive material loses its resistance around -211°FF. This limit is still so low because when temperature rises particles behave differently.

In our world, particles don’t cooperate with each other. Electrical wires get hot because charged particles, or electrons, repulse each other when moving through the wires. This repulsion makes it harder for the electrons to flow through the wires and the resistance to electrical current is dissipated into heat. In the same way, particles in a fluid are free to move in any direction. That creates the viscosity of the fluid and gives it a certain resistance to flow. That’s the reason why your wine could never squeeze through the head of a pin.

At ultra-low temperature, collaboration becomes golden rule. The resistance in mercury and the viscosity in liquid helium disappear because particles cooperate with each other. “[They] behave as if they were one and the same big atom,” explains Antonio Neto, Professor in the Department of Physics at Boston University. In other words, at room temperature particles act as if they were dancing at a Friday night techno party. They jump up and down in no order. But at very low temperature, particles couple and follow the same rhythm: just as if dancing a quiet waltz. However, this quiet dance doesn’t ease the interpretation of “super-solidity”; an even more counterintuitive state of matter near the absolute zero where solids are predicted to slide through each other like ghosts.

Physicists are scratching their heads over the outcome of one experiment. “We’re confident that [crystals have a] strange behavior near the absolute zero, but we’re not sure what it is,” explains David Huse, a professor of Physics at Princeton University. The all debate started when, in 2004, Moses Chan and his then student Eun-Seong Kim of Penn State University reported the first probable experimental evidence for a super-solid. Kim and Chan filled a tiny can with ultra-cold liquid helium and squeezed it to greater than 25 times the atmospheric pressure to make it solidify. They then set the can to twist back and forth on the top of a thin shaft. Below a temperature of about -459°F, the frequency of the twisting shot up as if the can had become less massive. That implied that some of the solid helium atoms were not moving while the rest of it continued to twist back and forth.

Let’s come back to your glass of wine for a moment. If you rotate it, the wine inside will rotate with the cup. But if now you rotate a super-fluid, you already know that you’ll see tiny vortices appearing, and that’s because some of the atoms of the super-fluid stay stationary while the glass rotates. So when Kim and Chan saw that some atoms of the crystals were not rotating with their container, they concluded they were probably observing super-fluidity of a solid. That in turn suggested that the solid helium was flowing like a liquid through itself without any resistance.

But Kim and Chan’s experiment later found different interpretations. John Beamish, Professor in condensed physics, at the University of Alberta, explains that what Chan and Kim observed could also be the consequences of a plastic deformation. Or what happens when bending or twisting a piece of metal. Beamish calls this kind of plastic behavior “a super mechanical behavior.” In addition, many theorists state that the outcome of Chan’s experiment depend strongly on the conditions under which the solid helium sample is prepared, and then does not reveal an intrinsic property of a solid at very low temperature. They believe that Kim and Chan observed less mysterious super-fluid liquid helium winding its way through imperfections in the crystals.

Some experiments illustrate that perfect crystals don’t flow at very low temperature. Sébastien Balibar and his colleagues at the Ecole Normale Supérieure in Paris, France, for example, used a barometer-like device to look for direct signs of “supersolidity.” They filled two communicating vessels to a different height with solid helium and used a camera to see if the two systems reached equilibrium. For crystals with defects, the team indeed observed a mass flow; but for almost perfect crystals, they didn’t observe such a behavior.

Now, Chan and colleagues Xi Lin and Anthony Clark have new results that suggest “supersolidity” may be a property of the solid helium crystal at very low temperature after all. At “normal” temperature, physicists can measure a peak that marks a transition from one state to another. During such transitions, like when freezing water is transformed into ice, the heat capacity of a material (or the amount of heat required to raise the temperature of the stuff) increases dramatically. And that’s what Chan and his colleagues saw in solid helium during their last experiment. But Clark cautions that they haven’t yet proved that the heat capacity signal, which actually occurs at a slightly lower temperature than the onset of flow, is tied to “supersolidity.” But if the peak is really there, it bolsters the case that “supersolidity” involves a real state transition and gives credentials to this new state of matter.

This ping-pong like exchanges of interpretations might appear as insignificant to your everyday life. But in a near future you might rub elbows with some of the super-cool world inhabitants. Even if those super-cool properties are not fully understood, applications are crapping up.

Superconductors are the solution to 100% efficiency and to full optimization of any machine. In Japan, the maglev levitating train could not reach the 300 miles per hour record without superconductors because it would require huge amounts of power. With superconducting magnets, once the magnetic field is generated, the train flows forever. Companies, such as American Superconductor based in Westborough, Massachusetts, estimate they could reach the market in two to three years. One of the world’s principal vendor in high-temperature superconductors, they are building prototype-superconducting electrical wires and motors. Jason Fredette, Director Media Relations at American Superconductor, explains that usual electrical wires lose 8 to 10% of energy through heating. On the opposite, “once induced in a superconducting loop, direct current can flow undiminished forever,” he adds.

Not only can those wires reduce the lost of energy, they also reduce the sizes of the machineries. For the same amount of power in delivery, a motor that American Superconductor prototyped for the U.S. Navy ships weighs 225 tons less. In the same way, machines for cancer protons therapy could shrink dramatically. This therapy uses particles beams to specifically target and kill the tumor without damaging surrounding tissue. “The equipment to generate the beams today occupy four very large rooms,” describes Dr. Peter Lee from the National High Magnetic field Laboratory in Florida. Not only would superconductors reduce the size of the machinery, but will they also bring down the price from up to $100 millions to $15 millions. Today, the less than ten centers delivering protons therapy in the U.S. could spread like mushrooms and facilitate access to this therapy.

However, this dream to super-cool efficiency still needs bulky refrigeration systems to get to those technological marvels. Optimistic scientists continue anyway to dream about room temperatures applications. If Neto was able to bring high temperature super-conduction in graphene, a one-atom layer material, he says he could make a computer as thin as a credit card. Martin Zwierlein, Associate Professor, Department of physics, MIT, adds that “in principle, there is nothing that tells that superconductivity is not possible at room temperature.”

Erasing Memory

Thu, 20 Dec 2007 23:27:00 +0100

In October of 2006, I interviewed Jonathan Whitlock, a post-doctorate associate at the Picower Institute at that time. On that day, he lighted up my fascination for memory, and its mechanisms in the human brain. At the end of the interview, he launched that he was erasing rats’ memory. And the whole story began.

Whitlock explained me he had trained a rat to avoid the dark side of a two- compartment box by giving him mild foot shocks whenever he entered that side. After the rat learned that task, Whitlock used an array of electrodes to listen in on many places at the same time in his hippocampus. Once he eavesdrops on the hard-to-detect signal of the memory forming, he manipulated it with the goal of impairing the memory.

“The idea is to watch the initial changes set in motion by learning, and reverse those changes applying the inverse patterned electrical stimulation,” he explained. When Whitlock put the rat back in the box, he said he didn’t remember he had to avoid the dark side. He got trained again and the responses to learning reappeared. His brain was intact and hadn’t been damaged.

Scientists at Work

Thu, 20 Dec 2007 23:21:00 +0100

In a small and dark laboratory at the Picower Institute in Cambridge, Massachusetts, a rat sits comfortably in a shine black plastic box. His long white and massive tail impress the visitors. He looks like a hybrid animal coming out of a Star Trek picture. A small metal chip implanted into his minuscule brain delicately deforms his scalp. Through that implant, scientists can record his neurons activity.

A deep and intense blow followed by several bips is emitted from the oscilloscope. “Listen, that’s the sound of the Eternal Sunshine of the Spotless Mind,” Jonathan Whitlock says. Whitlock, who was working at the MIT Picower Institute from 2002 to 2006, alludes to Michel Gondry’s movie in which a fictional company developed a procedure to erase targeted memories. In the film, the patients take a pill and wake up the day after with no memory of the event they have decided to erase. As frightening as it sounds, in today’s neuroscience laboratories reality flirts with fiction.

In the United States, between Cambridge and New York, researchers in neurobiology are developing new techniques to erase rats’ memory. They teach them a specific task, pinpoint the learning mechanism in their brains and reverse it or block it, using electrical patterns or chemistry, to impair the memory that has been formed.