Archive for March 26, 2011

A Fourth Domain of Life?

March 26, 2011 Leave a comment

“LIFE, like Caesar’s Gaul, is divided into three parts. The Linnaean system of classification, with its prescriptive hierarchy of species, genus, family, order, class, phylum and kingdom, ultimately lumps everything alive into one of three giant groups known as domains.

The most familiar domain, though arguably not the most important to the Earth’s overall biosphere, is the eukaryotes. These are the animals, the plants, the fungi and also a host of single-celled creatures, all of which have complex cell nuclei divided into linear chromosomes. Then there are the bacteria—familiar as agents of disease, but actually ecologically crucial. Some feed on dead organic matter. Some oxidise minerals. And some photosynthesise, providing a significant fraction (around a quarter) of the world’s oxygen. Bacteria, rather than having complex nuclei, carry their genes on simple rings of DNA which float around inside their cells.

The third great domain of life, the archaea, look, under a microscope, like bacteria. For that reason, their distinctiveness was recognised only in the 1970s. Their biochemistry, however, is very different from that of bacteria (they are, for example, the only organisms that give off methane as a waste product), and their separate history seems to stretch back billions of years.

But is that it? Or are there other biological domains hiding in the shadows—missed, like the archaea were for so long, because biologists have been using the wrong tools to look? That is the question asked recently by Jonathan Eisen of the University of California, Davis, and his colleagues. They suspect there are, and in a paper just published in the Public Library of Science, they present an analysis which suggests there might indeed be at least one other, previously hidden, domain of life.”

Flexible, Plastic Microprocessor Developed

March 26, 2011 Leave a comment

Plastic power: This microprocessor is made from organic materials. It is puny compared to most silicon processors, but is flexible and cheap. Credit: IMEC

“Silicon may underpin the computers that surround us, but the rigid inflexibility of the semiconductor means it cannot reach everywhere. The first computer processor and memory chips made out of plastic semiconductors suggest that, someday, nowhere will be out of bounds for computer power.

Researchers in Europe used 4,000 plastic, or organic, transistors to create the plastic microprocessor, which measures roughly two centimeters square and is built on top of flexible plastic foil. “Compared to using silicon, this has the advantage of lower price and that it can be flexible,” says Jan Genoe at the IMEC nanotechnology center in Leuven, Belgium. Genoe and IMEC colleagues worked with researchers at the TNO research organization and display company Polymer Vision, both in the Netherlands.

The processor can so far run only one simple program of 16 instructions. The commands are hardcoded into a second foil etched with plastic circuits that can be connected to the processor to “load” the program. This allows the processor to calculate a running average of an incoming signal, something that a chip involved in processing the signal from a sensor might do, says Genoe. The chip runs at a speed of six hertz-on the order of a million times slower than a modern desktop machine-and can only process information in eight-bit chunks at most, compared to 128 bits for modern computer processors. ”

The Mysterious Pseudogap

March 26, 2011 Leave a comment

“Scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have joined with researchers at Stanford University and the SLAC National Accelerator Laboratory to mount a three-pronged attack on one of the most obstinate puzzles in materials sciences: what is the pseudogap?

A collaboration organized by Zhi-Xun Shen, a member of the Stanford Institute for Materials and Energy Science (SIMES) at SLAC and a professor of physics at Stanford University, used three complementary experimental approaches to investigate a single material, the high-temperature superconductor Pb-Bi2201 (lead bismuth strontium lanthanum copper-oxide). Their results are the strongest evidence yet that the pseudogap phase, a mysterious electronic state peculiar to high-temperature superconductors, is not a gradual transition to superconductivity in these materials, as many have long believed. It is in fact a distinct phase of matter.”