February 15, 2007, 6:21 AM CT

DNA to detect hazardous uranium ions

Researchers at the University of Illinois at Urbana-Champaign have developed a simple, disposable sensor for detecting hazardous uranium ions, with sensitivity that rivals the performance of much more sophisticated laboratory instruments.

The sensor provides a fast, on-site test for assessing uranium contamination in the environment, and the effectiveness of remediation strategies, said Yi Lu, a chemistry professor at Illinois and senior author of a paper accepted for publication in the Proceedings of the National Academy of Sciences, and posted on its Web site.

A unique feature of our uranium sensor is that it contains a small piece of DNA, the same basic building blocks of our genes, said Lu, who also is a researcher at the universitys Beckman Institute for Advanced Science and Technology, and at the Center of Advanced Materials for the Purification of Water with Systems. Our sensor combines the high metal ion selectivity of catalytic DNA with the high sensitivity of fluorescence detection.

While most DNA is double stranded, the catalytic DNA Lus research group uses has a single strand region that can wrap around like a protein. In that single strand, the researchers fashion a specific binding site a kind of pocket that can only accommodate the metal ion of choice......... Posted by: Beverly      Read more         Source

February 15, 2007, 4:40 AM CT

LSU Professor Resolves Einstein's Twin Paradox

Delaune Distinguished Professor of Electrical and Computer Engineering at LSU, recently resolved the twin paradox, known as one of the most enduring puzzles of modern-day physics.

First suggested by Albert Einstein more than 100 years ago, the paradox deals with the effects of time in the context of travel at near the speed of light. Einstein originally used the example of two clocks one motionless, one in transit. He stated that, due to the laws of physics, clocks being transported near the speed of light would move more slowly than clocks that remained stationary. In more recent times, the paradox has been described using the analogy of twins. If one twin is placed on a space shuttle and travels near the speed of light while the remaining twin remains earthbound, the unmoved twin would have aged dramatically compared to his interstellar sibling, according to the paradox.

If the twin aboard the spaceship went to the nearest star, which is 4.45 light years away at 86 percent of the speed of light, when he returned, he would have aged 5 years. But the earthbound twin would have aged more than 10 years! said Kak.

The fact that time slows down on moving objects has been documented and verified over the years through repeated experimentation. But, in the previous scenario, the paradox is that the earthbound twin is the one who would be considered to be in motion in relation to the sibling and therefore should be the one aging more slowly. Einstein and other scientists have attempted to resolve this problem before, but none of the formulas they presented proved satisfactory......... Posted by: Beverly      Read more         Source

February 13, 2007, 9:29 PM CT

The colourful demise of a Sun-like star

A brand new image taken with Hubble's Wide Field Planetary Camera 2 shows the planetary nebula NGC 2440 - the chaotic structure of the demise of a star.

This image, just taken by the NASA/ESA Hubble Space Telescope, shows the colourful "last hurrah" of a star like our Sun. The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the centre. Our Sun will eventually burn out and shroud itself with stellar debris, but not for another 5 billion years.

Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae. The objects have nothing to do with planets. Eighteenth- and nineteenth-century astronomers called them the name because through small telescopes they resembled the disks of the distant planets Uranus and Neptune. The planetary nebula in this image is called NGC 2440. The white dwarf at the centre of NGC 2440 is one of the hottest known, with a surface temperature of more than 200,000 degrees Celsius. The nebula's chaotic structure suggests that the star shed its mass episodically. During each outburst, the star expelled material in a different direction. This can be seen in the two bowtie-shaped lobes. The nebula also is rich in clouds of dust, some of which form long, dark streaks pointing away from the star. NGC 2440 lies about 4,000 light-years from Earth in the direction of the constellation Puppis......... Posted by: Beverly      Read more         Source

February 13, 2007, 9:10 PM CT

Water Through Nanotube Membranes

Troy, N.Y. By fusing wet and dry nanotechnologies, researchers at Rensselaer Polytechnic Institute have found a way to control the flow of water through carbon nanotube membranes with an unprecedented level of precision. The research, which will be described in the March 14, 2007 issue of the journal Nano Letters, could inspire technologies designed to transform salt water into pure drinking water almost instantly, or to immediately separate a specific strand of DNA from the biological jumble.

Nanotube membranes have fascinated researchers with their combination of high flow rates and high selectivity, allowing them to filter out very small impurities and other organic materials like DNA and proteins from materials with high water content. The problem is that nanotube arrays are hydrophobic, strongly repelling water.

We have, at a very fundamental level, discovered that there is a new mechanism to control water transport, said Nikhil Koratkar, associate professor of mechanical engineering at Rensselaer and lead author of the paper. This is the first time that electrochemical means can be used to control the way that the water interacts with the surface of the nanotube.

A group of Rensselaer researchers led by Koratkar has found a way to use low-voltage electricity to manipulate the flow of water through nanotubes. Control of waters movement through a nanotube with this level of precision has never been demonstrated before......... Posted by: Beverly      Read more         Source

February 13, 2007, 9:06 PM CT

Nuclear Fusion As Energy Source

For about six months of the year, bursts of a hot, electrically charged gas, or plasma, swirl around a donut-shaped tube in a special MIT reactor, helping researchers learn more about a potential future energy source: nuclear fusion.

During downtimes when the reactor is offline, as it is right now, engineers make upgrades that will help them achieve their goal of making fusion a viable energy source--a long-standing mission that will likely continue for decades.

MIT's reactor, known as Alcator C-Mod, is one of several tokamak plasma discharge reactors in the world. Inside the reactor, magnetic fields control the superheated plasma (up to 50 million degrees Kelvin) as it flows around the tube.

Fusion occurs when two deuterons, or one deuteron and one triton--nuclei of heavy hydrogen--fuse, creating helium and releasing energy. The reactions can only occur at extremely high temperatures.

Eventhough MIT's reactor is smaller than others, it has a stronger magnetic field than some larger reactors, allowing the plasma to become denser at comparable temperatures. "That positions us to provide important data you can't get anywhere else," said Earl Marmar, head of MIT's Alcator C-Mod project and senior research scientist in the Department of Physics......... Posted by: Beverly      Read more         Source

February 12, 2007, 9:40 PM CT

More than meets the tongue

Does orange juice taste sweeter if it's a brighter orange? A new study in the recent issue of the Journal of Consumer Research finds that the color of a drink can influence how we think it tastes. In fact, the researchers found that color was more of an influence on how taste was perceived than quality or price information.

"Perceptual discrimination is fundamental to rational choice in many product categories yet rarely examined in consumer research," write JoAndrea Hoegg (University of British Columbia) and Joseph W. Alba (University of Florida). "The present research investigates discrimination as it pertains to consumers' ability to identify differenceor the lack thereofamong gustatory stimuli".

Hoegg and Alba are the first to look at how individual attributes -- such as color, price, or brand -- can affect which products we prefer. The researchers manipulated orange juice by changing color (with food coloring), sweetness (with sugar), or by labeling the cups with brand and quality information. They found that though brand name influenced people's preferences for one cup of juice over another, labeling one cup a premium brand and the other an inexpensive store brand had no effect on perceptions of taste.

In contrast, the tint of the orange juice had a huge effect on the taster's perceptions of taste. As the authors put it: "Color dominated taste"......... Posted by: Ethen      Read more         Source

February 12, 2007, 8:59 PM CT

Natural Selection Continues

Some breaking news, just in time for Valentine's Day: Researchers have identified something called "sperm competition" that they think has evolved to ensure a genetic future. In sexual reproduction, natural selection is generally thought of as something that happens prior to and in fact leads to -- the Big Event. This thinking holds, for example, that we are drawn to physical features that tell us our partner is healthy and will give us a fighting chance to carry on our genetic lineage. But a new article in the recent issue of Current Directions in Psychological Science suggests that the human male has evolved mechanisms to pass on his genes during post-copulation as well, a phenomenon dubbed "sperm competition."

In their article, Todd Shackelford and Aaron Goetz at Florida Atlantic University describe this as "the inevitable consequence of males competing for fertilizations".

How much more romantic can you get?

For a monogamous species, sperm competition may seem beside the point. But according to the authors, extra curricular copulations (i.e. affairs) appear to be a significant part of our ancestral history and could, evolutionarily speaking, spell disaster. A male whose female partner engages in some off-line dalliances unwittingly may be investing his resources food, protection, credit rating -- in a genetically unrelated offspring......... Posted by: Beverly      Read more         Source

February 11, 2007, 9:32 PM CT

New mechanism for nutrient uptake discovered

Stanford, CABiologists at the Carnegie Institution's Department of Plant Biology have discovered a new way that plant cells govern nutrient regulationneighboring pore-like structures at the cell's surface physically interact to control the uptake of a vital nutrient, nitrogen. It is the first time scientists have found that the interaction of neighboring molecules is essential to this regulation. Since plants, animals, bacteria, and fungi all share similar genes for this activity, the scientists believe that the same feature could occur across species. The discovery, published in the February 11th on-line edition of Nature, has widespread potentialfrom understanding human diseases, such as kidney function, to engineering better crops.

"Every cell in every organism has a system for bringing in nutrition and expelling waste," explained lead author Dominique Loqu. "Some are through pore-like protein structures called transporters, which reside at the surface of the cell's outer membrane. Each pore is capable of transporting nutrients individually, so we were really surprised to find that the pores simply can't act without stimulation from their neighbors".

In earlier research the Carnegie scientists, with colleagues, identified the genes responsible for initiating nitrogen uptake in plants. That identification has helped other researchers find the relatives of these genes in a variety of species from bacteria to humans. In this study, the scientists wanted to identify how ammonium transport is regulated.........

Posted by: Beverly      Read more         Source

February 11, 2007, 8:49 PM CT

Wildlife Birth-control Method

Professor Cooper also raises concerns that individuals that survive the vaccine may be more likely to carry infectious diseases with the potential to affect other animals.

An immuno-contraceptive vaccine causes an animal's immune system to produce antibodies that act against some essential event or structure in the reproductive process. The antibodies can act against sperm, eggs or reproductive hormones, which prevent either fertilization or the production of sperm and ova.

Proponents of the technique, which was first tested nearly 20 years ago, regard it as more humane than the conventional methods of controlling wildlife populations, such as shooting, trapping, poisoning or viral diseases. It has drawn support from some politicians and animal-welfare agencies.

An expert in mammal reproduction, Professor Cooper, of the UNSW School of Biological, Earth and Environmental Sciences, questions immuno-contraception on three grounds.

"Firstly, immuno-contraceptives are ineffective against substantial minorities of animals, probably for genetic reasons," Professor Cooper says. "If so, the genes responsible for this lack of response will be passed on to offspring. Within a few generations most of the population will be unresponsive to the immunocontraceptive, so its effectiveness as a form of birth control is likely to be short-lived".........

Posted by: Beverly      Read more         Source

February 9, 2007, 4:38 AM CT

Nanotechnology meets biology

The object of fascination for most is the DNA molecule. But in solution, DNA, the genetic material that hold the detailed instructions for virtually all life, is a twisted knot, looking more like a battered ball of yarn than the famous double helix. To study it, scientists generally are forced to work with collections of molecules floating in solution, and there is no easy way to precisely single out individual molecules for study.

Now, however, scientists have developed a quick, inexpensive and efficient method to extract single DNA molecules and position them in nanoscale troughs or "slits," where they can be easily analyzed and sequenced.

The technique, which according to its developers is simple and scalable, could lead to faster and vastly more efficient sequencing technology in the lab, and may one day help underpin the ability of clinicians to obtain customized DNA profiles of patients.

The new work is reported this week (Feb. 8, 2007) in the Proceedings of the National Academies of Science (PNAS) by a team of scientists and engineers from the University of Wisconsin-Madison.

"DNA is messy," says David C. Schwartz, a UW-Madison genomics researcher and chemist and the senior author of the PNAS paper. "And in order to read the molecule, you have to present the molecule".........

Posted by: Beverly      Read more         Source