Thursday, January 01, 2009
Thursday, December 04, 2008
“There’s been a lot of progress,” says physicist Earl Marmar, division head of the Alcator Project at the MIT Plasma Science and Fusion Center (PSFC). “We’re learning a lot more about the details of how these things work.”
The Alcator C-Mod reactor, in operation since 1993, has the highest magnetic field and the highest plasma pressure of any fusion reactor in the world, and is the largest fusion reactor operated by any university.
One of the most vexing issues facing those trying to construct a fusion plant that produces more power than it consumes (something never achieved yet experimentally) is how to propel the hot plasma (an electrically charged gas) around inside the donut-shaped reactor chamber. This is necessary to keep it from losing its heat of millions of degrees to the cooler vessel walls. Now, the MIT scientists think they may have found a way.
The advance, made by scientists from Oregon State University and Norfolk State University, was just published in Physical Review Letters.
“The ability to compensate for optical loss is a very large step forward for the whole field of active plasmonics,” said Viktor Podolskiy, an OSU assistant professor of physics. “Some of the most important potential applications in this field have been held back by this problem.”
These “metamaterials,” which gain their properties from their structure rather than directly from their composition, have been seen as a key to a possible “super lens” that would have an extraordinary level of resolution and be able to “see” things the size of a nanometer – a human hair is 100,000 nanometers wide.
They could also be important in machine visions systems, electronics manufacturing, computers limited only by the speed of light, and a range of new communications concepts. A “cloaking device” to hide objects, although not exactly of the type made famous by Star Trek, is also a possibility.
Saturday, November 29, 2008
In a back room of New Scientist's offices in London, I sit
down at a table with the Russian biochemist Mikhail Shchepinov. In
front of us are two teaspoons and a brown glass bottle. Shchepinov
opens the bottle, pours out a teaspoon of clear liquid and drinks it
down. He smiles. It's my turn.
I put a spoonful of the liquid in my mouth and swallow. It tastes
slightly sweet, which is a surprise. I was expecting it to be exactly
like water since that, in fact, is what it is - heavy water to be
precise, chemical formula D2O. The D stands for deuterium,
an isotope of hydrogen with an atomic mass of 2 instead of 1. Deuterium
is what puts the heavy in heavy water. An ice cube made out of it would
sink in normal water.
Tuesday, November 25, 2008
Cancer, diabetes, Alzheimer's, Parkinson's, heart disease: All have stubbornly resisted billions of dollars of research conducted by the world's finest minds. But they all may finally be defied by a single new class of drugs, a virtual cure for the diseases of aging.
In labs across the country, researchers are developing several new drugs that target the cellular engines called mitochondria. The first, resveratrol, is already in clinical trials for diabetes. It could be on the market in four years and used off-label as an all-purpose longevity enhancer. Other drugs promise to be more potent and refined. They might even be cheap.
Friday, November 21, 2008
Matter is built on flaky foundations. Physicists have now confirmed that the apparently substantial stuff is actually no more than fluctuations in the quantum vacuum.
The researchers simulated the frantic activity that goes on inside protons and neutrons. These particles provide almost all the mass of ordinary matter.
Each proton (or neutron) is made of three quarks - but the individual masses of these quarks only add up to about 1% of the proton's mass. So what accounts for the rest of it?
Theory says it is created by the force that binds quarks together, called the strong nuclear force. In quantum terms, the strong force is carried by a field of virtual particles called gluons, randomly popping into existence and disappearing again. The energy of these vacuum fluctuations has to be included in the total mass of the proton and neutron.
Thursday, November 20, 2008
However, Roy’s controversial ideas on how the brain works and learns probably won’t immediately win over many of his colleagues, who have spent decades teaching robots and artificial intelligence (AI) systems how to think using the classic connectionist theory of the brain. Connectionists propose that the brain consists of an interacting network of neurons and cells, and that it solves problems based on how these components are connected. In this theory, there are no separate controllers for higher level brain functions, but all control is local and distributed fairly equally among all the parts.
In his paper, Roy argues for a controller theory of the brain. In this view, there are some parts of the brain that control other parts, making it a hierarchical system. In the controller theory, which fits with the so-called computational theory, the brain learns lots of rules and uses them in a top-down processing method to operate. In 1997, IBM’s Deep Blue computer, which famously defeated world chess champion Garry Kasparov, operated based on countless rules entered by its programmers.
More information: Roy, Asim. “Connectionism, Controllers, and a Brain Theory.” IEEE Transactions on Systems, Man, and Cybernetics – Part A: Systems and Humans, Vol. 38, No. 6, November 2008.
Rumelhart, D. E. and J. L. McClelland, Eds., Parallel Distributed Processing: Explorations in Microstructure of Cognition, vol. 1. Cambridge, MA: MIT Press, 1986, pp. 318–362.
NSF’s summary of the “Open Questions in Both Biological and Machine Learning” http://www.cnl.salk.edu/Media/NSFWorkshopReport.v4.pdf
ANNIE Conference Web site http://annie.mst.edu/annie_2008/ANNIE2008.html
Friday, November 14, 2008
A drug extracted from a plant used in Chinese medicine has helped immune cells fight HIV and raises the possibility of slowing the ageing process in other parts of our bodies.
The method hinges upon telomeres - caps of repetitive DNA found at the ends of chromosomes. These get shorter as cells age and are thought to affect the cell's lifespan.
The caps can be rebuilt with an enzyme called telomerase, and some people have suggested it might be possible to extend human life by boosting telomerase production - though this has never been tested.
Now Rita Effros at the University of California in Los Angeles has used a drug that boosts telomerase to enhance the immune response to viruses.
Effros and her colleagues had previously inserted part of the telomerase gene into so-called killer T-cells - immune cells that fight infections including HIV - and found that the cells had stronger anti-viral activity than normal. However, such gene therapy is not a practical way of treating the millions of people infected with HIV.