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April 17, 2006, 10:10 PM CT

Exploding Stars

Exploding Stars
Artist's impression of the explosion of RS Ophiuchi. Image Credit: David A. Hardy.
amateur astronomers reported that a faint star in the constellation of Ophiuchus had suddenly become clearly visible in the night sky without the aid of a telescope. Records show that this so-called recurrent nova, RS Ophiuchi (RS Oph), has previously reached this level of brightness five times in the last 108 years, most recently in 1985. The latest explosion has been observed in unprecedented detail by an armada of space- and ground-based telescopes.

Speaking today (Friday) at the RAS National Astronomy Meeting at Leicester, Professor Mike Bode of Liverpool John Moores University and Dr Tim O'Brien of Jodrell Bank Observatory will present the latest results which are shedding new light on what happens when stars explode.

RS Oph is just over 5,000 light years away from Earth. It consists of a white dwarf star (the super-dense core of a star, about the size of the Earth, that has reached the end of its main hydrogen-burning phase of evolution and shed its outer layers) in close orbit with a much larger red giant star.

The two stars are so close together that hydrogen-rich gas from the outer layers of the red giant is continuously pulled onto the dwarf by its high gravity. After around 20 years, enough gas has been accreted that a runaway thermonuclear explosion occurs on the white dwarf's surface. In less than a day, its energy output increases to over 100,000 times that of the Sun, and the accreted gas (several times the mass of the Earth) is ejected into space at.........

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April 17, 2006, 10:06 PM CT

Paint-on Laser To Rescue Computer Chip

Paint-on Laser To Rescue Computer Chip
Researchers at the University of Toronto have created a laser that could help save the $200-billion dollar computer chip industry from a looming crisis dubbed the "interconnect bottleneck".

But this isn't a laser in the stereotypical sense -- no corded, clunky boxes projecting different coloured lights. In fact, Professor Ted Sargent, of the Edward S. Rogers Sr. Department of Electrical and Computer Engineering, carries a small vial of the paint used to make this laser in his briefcase -- it looks like diluted ink.

Lasers that can produce coherent infrared light in the one to two nanometre wavelength range are essential in telecommunications, biomedical diagnosis and optical sensing. The speed and density of computer chips has risen exponentially over the years, and within 15 to 20 years the industry is expected to reach a point where components can't get any faster. But the interconnect bottleneck -- the point where microchips reach their capacity -- is expected sometime around 2010.

To tackle this problem, Sargent, a Canada Research Chair in Nanotechnology, created the new laser using colloidal quantum dots -- nanometre-sized particles of semiconductor that are suspended in a solvent like the particles in paint. "We've made a laser that can be smeared onto another material," says Sargent. "This is the first paint-on semiconductor laser to produce the invisible colours of light needed to carry information through fiber-optics. The infrared light could, in the future, be used to connect microprocessors on a silicon computer chip." A study describing the laser was published in the April 17 issue of the journal Optics Express.........

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April 15, 2006, 3:47 PM CT

Graphite-based Circuitry May Be Foundation For New Devices

Graphite-based Circuitry May Be Foundation For New Devices Caption: Scanning electron microscope image of nano-patterned epitaxial ultra-thin graphite films shows a hall bar structure used to measure transport properties under magnetic fields. Credit: Image courtesy Zhimin Song
A study of how electrons behave in circuitry made from ultrathin layers of graphite - known as graphene - suggests the material could provide the foundation for a new generation of nanometer scale devices that manipulate electrons as waves - much like photonic systems control light waves.

In a paper published April 13 in Science Express, an online advance publication of the journal Science, scientists at the Georgia Institute of Technology and the Centre National de la Recherche Scientifique (CNRS) in France report measuring electron transport properties in graphene that are comparable those seen in carbon nanotubes. Unlike carbon nanotubes, however, graphene circuitry can be produced using established microelectronics techniques, allowing scientists to envision a "road map" for future high-volume production.

"We have shown that we can make the graphene material, that we can pattern it, and that its transport properties are very good," said Walt de Heer, a professor in Georgia Tech's School of Physics. "The material has high electron mobility, which means electrons can move through it without much scattering or resistance. It is also coherent, which means electrons move through the graphene much like light travels through waveguides."

The results should encourage further development of graphene-based electronics, though de Heer cautions that practical devices may be a decade away.........

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April 14, 2006, 9:26 AM CT

Peep Into Universe

Peep Into Universe

An image made of about 300 million pixels is being released by ESO, based on more than 64 hours of observations with the Wide-Field Camera on the 2.2m telescope at La Silla (Chile). The image covers an 'empty' region of the sky five times the size of the full moon, opening an exceptionally clear view towards the most distant part of our universe. It reveals objects that are 100 million times fainter than what the unaided eye can see.

Easter is in a number of countries a time of great excitement for children who are on the big hunt for chocolate eggs, hidden all about the places. Astronomers, however, do not need to wait this special day to get such an excitement: it is indeed daily that they look for faraway objects concealed in deep images of the sky. And as with chocolate eggs, deep sky objects, such as galaxies, quasars or gravitational lenses, come in the wildest variety of colours and shapes.

The image presented here is one of such very deep image of the sky. It is the combination of 714 frames for a total exposure time of 64.5 hours obtained through four different filters (B, V, R, and I)! It consists of four adjacent Wide-Field Camera pointings (each 33x34 arcmin), covering a total area larger than one square degree.

Yet, if you were to look at this large portion of the firmament with the unaided eye, you would just see. nothing. The area, named Deep 3, was indeed chosen to be a random but empty, high galactic latitude field, positioned in such a way that it can be observed from the La Silla observatory all over the year.........

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April 12, 2006, 11:56 PM CT

U.S.-Taiwan Constellation Of Satellites

U.S.-Taiwan Constellation Of Satellites We have liftoff. COSMIC satellites will take to the atmosphere this week. Credit: University Corporation for Atmospheric Research/National Center for Atmospheric Research
A globe-spanning constellation of six satellites expected to improve weather forecasts, monitor climate change, and enhance space weather research will head into orbit on Fri. April 14, 2006. Barring delays, a Minotaur rocket is scheduled to launch the array at 5:10 p.m. Pacific time from Vandenberg Air Force Base on the central Calif. coast.

The low-orbiting satellites will be the first to provide atmospheric data daily in real time over thousands of points on Earth for both research and operational weather forecasting. The satellites will measure the bending of radio signals from the U.S. Global Positioning System (GPS) as the signals pass through Earth's atmosphere.

Called COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) in the United States and FORMOSAT-3 in Taiwan, the $100 million satellite network is the product of an agreement between the American Institute in Taiwan and the Taipei Economic and Cultural Representative Office in the United States. The array is based on a system design provided by the University Corporation for Atmospheric Research (UCAR).

Temperature and water vapor profiles derived from the GPS data will help meteorologists observe, research, and forecast hurricanes, typhoons, and other storm patterns over the oceans and improve a number of areas of weather prediction. The stability, consistency, and accuracy of the measurements will provide critical new information to researchers quantifying long-term climate change trends, say atmospheric scientists.........

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April 12, 2006, 11:48 PM CT

Lunar Rocks Suggest Meteorite Shower

Lunar Rocks Suggest Meteorite Shower
New age measurements of lunar rocks returned by the Apollo space missions have revealed that a surprising number of the rocks show signs of melting about 3.9 billion years ago, suggesting that the moon - and its nearby neighbor Earth - were bombarded by a series of large meteorites at that time.

The idea that meteorites have hammered the moon's surface isn't news to scientists. The lunar surface is pock-marked with large craters carved out by the impact of crashing asteroids and meteorites, said Robert Duncan, a professor and associate dean in the College of Oceanic and Atmospheric Sciences at Oregon State University.

But the narrow range of the impact dates suggests to scientists that a large spike in meteorite activity took place during a 100-million year interval - possibly the result of collisions in the asteroid belt with comets coming from just beyond our solar system.

Results of the study are being published in Geochimica et Cosmochimica Acta, the journal of the international Meteoritical Society. Co-authors with Duncan are Marc Norman of the Australian National University and John Huard, also an oceanographer at OSU. The study was funded by NASA.

Tiny melted fragments from the lunar rocks were dated at the noble gas geochronology laboratory at Oregon State. Duncan and Huard were able to use radiometric dating techniques to determine when the rocks had melted after being struck by meteorites. What is especially intriguing, Duncan says, is that this apparent spike in meteorite activity took place about 3.8 to 4 billion years ago - an era that roughly coincides with when researchers believe life first began on Earth, as evidenced by the fossil record of primitive one-cell bacteria.........

Posted by: Edwin      Permalink         Source


April 12, 2006, 11:38 PM CT

Motor To Single-molecule Car

Motor To Single-molecule Car
In follow-on work to last year's groundbreaking invention of the world's first single-molecule car, chemists at Rice University have produced the first motorized version of their tiny nanocar.

The research is published in the April 13 issue of the journal Organic Letters.

"We want to construct things from the bottom up, one molecule at a time, in much the same way that biological cells use enzymes to assemble proteins and other supermolecules," said lead researcher James M. Tour, the Chao Professor of Chemistry, professor of mechanical engineering and materials science and professor of computer science. "Everything that's produced through biology - from the tallest redwood to largest whale - is built one molecule at a time. Nanocars and other synthetic transporters may prove to be a suitable alternative for bottom-up systems where biological methods aren't practical".

The motorized model of the nanocar is powered by light. Its rotating motor, a molecular framework that was developed by Ben L. Feringa at the University of Groningen in the Netherlands, was modified by Tour's group so that it would attach in-line with the nanocar's chassis. When light strikes the motor, it rotates in one direction, pushing the car along like a paddlewheel.

The first nanocar research paper, published the journal Nano Letters last October, was the most-accessed article from all American Chemical Society journals in 2005. That paper was co-authored by Kevin Kelly, assistant professor of electrical and computer engineering.........

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April 11, 2006, 11:27 PM CT

Venus Express Enters Orbit Around The Hothouse Planet

Venus Express Enters Orbit Around The Hothouse Planet Artist's impression of the Venus Express orbit insertion on 11 April 2006.
ESA PR 13-2006. This morning, at the end of a 153-day and 400-million km cruise into the inner Solar System beginning with its launch on 9 November 2005, ESA's Venus Express space probe fired its main engine at 09:17 CEST for a 50-minute burn, which brought it into orbit around Venus.

With this firing, the probe reduced its relative velocity toward the planet from 29,000 to about 25,000 km/h and was captured by its gravity field. This orbit insertion manoeuvre was a complete success.

During the next four weeks, the Venus Express probe will perform a series of manoeuvres to reach the scheduled operational orbit for its scientific mission. It will move from its current highly elongated 9-day orbit to a 24-hour polar orbit, culminating at 66,000 kilometres. From this vantage point, the orbiter will conduct an in-depth observation of the structure, chemistry and dynamics of the atmosphere of Venus for at least two Venusian days (486 Earth days).

Enigmatic atmosphere

From prior missions to Venus as well as observations directly from Earth, we already know that our neighbouring planet is shrouded in a thick atmosphere where extremes of temperature and pressure conditions are common. This atmosphere creates a greenhouse effect of tremendous proportions as it spins around the planet in four days in an unexplained 'super-rotation' phenomenon.........

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April 11, 2006, 5:36 PM CT

Saturn Still Wearing Floods

Saturn Still Wearing Floods
The Detroit News reports: Saturn: It craves to be cool again. Cool? Saturn wants to be cool? We're not sure Saturn could handle the cool. We think Saturn needs to focus on what it stands for rather than shooting for cool because we just don't know what Saturn stands for anymore.........

Posted by: Edwin      Permalink


April 10, 2006, 7:09 PM CT

Nano-technology To Kill Cancer Cells

Nano-technology To Kill Cancer Cells
Research studies, based at the University of Pennsylvania, demonstrate that biodegradable nano-particles containing two potent cancer-fighting drugs are effective in killing human breast tumors. The unique properties of the hollow shell nano-particles, known as polymersomes, allow them to deliver two distinct drugs, paclitaxel, the leading cancer drug known by brand names such as Taxol, and doxorubicin directly to tumors implanted in mice. Their findings, presented online in the journal Molecular Pharamaceutics, illustrate the broad clinical potential of polymersomes.

"The system provides a number of advantages over other Trojan horse-style drug delivery system, and should prove a useful tool in fighting a number of diseases," said Dennis Discher, a professor in Penn's School of Engineering and Applied Science and a member of Penn newly established Institute for Translational Medicine and Therapeutics. "Here we show that drug-delivering polymersomes will break down in the acidic environment of the cancer cells, allowing us to target these drugs within tumor cells."

One key feature of molecular mechanism involves putting pores in the cancer cell membranes and has been simulated with supercomputers by Michael F. Klein and Goundla Srinivas of Penn's Department of Chemistry. While cell membranes and liposomes (vesicles often used for drug-delivery) are created from a double layer of fatty molecules called phospholipids, a polymersome is comprised of two layers of synthetic polymers. The individual polymers are degradable and considerably larger than individual phospholipids but have many of the same chemical features. This results in a structure that looks like a very small cell or virus.........

Posted by: John      Permalink         Source


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