jo la science - Home

Introducing Dennis

2010-01-25T05:11:00Z

Dennis owns a chrome shop in West-Memphis, Arkansas. We met him on the road to New-Orleans.

Detroit - Larry

2010-01-15T03:33:00Z

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.

I.R.R.M. LeBlog

2009-02-24T19:54:00Z

I.R.R.M., ou l’Introspection Radiophonique 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.

Houseflies Inspire Rescue Robots

2008-07-01T06:39:00Z

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. Watch the video…

Walter Lewin

2008-03-06T06:41:00Z

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 Domínguez and Eva Zadeh. - Classroom footage provided by MIT. (http://web.mit.edu/physics/facultyandstaff/faculty/walter_lewin.html)-

A Human Brain Bank

2008-01-09T06:21:00Z

If you leave a piece of human brain at room temperature, and wait to see what happens…it will simply melt and disappear. Indeed, 80% of our brain is just made out of fat and water. That’s what Katerina Mancevska, the Assistant Director of Tissue Processing at the New-York Brain Bank explains.

On the second basement floor of the Babies and Children’s Hospital of New York- Presbyterian, the New-York Brain Bank stores 1,500,000 samples of cells that come out of almost 500 postmortem human brains. The Bank was established in 2001, to meet with the needs of neuroscientists investigating specific psychiatric and neurological disorders like Alzheimer disease, Huntington disease, or Parkinson disease.

To understand the molecular process of those diseases that impinge on human memory, some researchers decide to study human cells instead of working with animals or brain imagery. They look at cells in two-tenths of an inch thin sort of salami-slices-like pieces of human brains. Once under their microscope, the cells stay “alive” for about eight hours from the time the sample gets unfrozen, after which they can’t exploit the sample anymore.

A simple online request will give the researchers an open access to this supermarket of human brain cells. They would need to answer a set of 20 questions about their work, and within 5-working days their request is treated and the samples shipped to their labs. The New-York Brain Bank collaborates with labs in Italy, Poland, Australia, and Japan as well as with in-house labs.

In the refrigerated room, the samples get stored by tracking numbers in seven huge freezers at -112°F. To keep the cells intact, the neuropathologists in charge of the dissection work meticulously.

Listen to Mancevska explaining how they operate.

SuperCool World

2007-12-21T01:32:00Z

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°F. 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

2007-12-20T22:27:00Z

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.

MIT Piano Training

2007-09-29T20:00:00Z

Bach, Beethoven, Mozart, Rachmaninoff… You dream that one day you could play the piano, and let your fingers fly on the keyboard. But here is the problem you can’t have your hands do two different things simultaneously. Don’t despair, there might be a machine that could help you practice.