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Dust Detected Around A Primitive Star, Shedding New Light On Universe's Origins

Dwarf galaxy
© Palomar Digitized Sky Survey
The Sculptor Dwarf galaxy, with the position of carbon star MAG 29 noted.
A Cornell-led team of astronomers has observed dust forming around a dying star in a nearby galaxy, giving a glimpse into the early universe and enlivening a debate about the origins of all cosmic dust.

The findings are reported in the Jan. 16 issue of the journal Science (Vol. 323, No. 5912). Cornell research associate Greg Sloan led the study, which was based on observations with NASA's Spitzer Space Telescope. The researchers used Spitzer's Infrared Spectrograph, which was developed at Cornell.

Dust plays a key role in the evolution of such galaxies as our Milky Way. Stars produce dust - rich with carbon or oxygen - as they die. But less is known about how and what kind of dust was created in galaxies as they formed soon after the big bang.

Chalkboard

Adaptation Plays a Significant Role in Human Evolution

For years researchers have puzzled over whether adaptation plays a major role in human evolution or whether most changes are due to neutral, random selection of genes and traits.

Geneticists at Stanford now have laid this question to rest. Their results, scheduled to be published Jan. 16 online in Public Library of Science Genetics, show adaptation-the process by which organisms change to better fit their environment-is indeed a large part of human genomic evolution.

"Others have looked for the signal of widespread adaptation and couldn't find it. Now we've used a lot more data and did a lot of work cleaning it up," said Dmitri Petrov, associate professor of biology at Stanford University and one of two senior authors of the paper. "We were able to detect the adaptation signatures quite clearly, and they have the characteristic shape we anticipated."

Info

Study finds that odors can alter gene expression in an olfactory neuron

New research from University of California, Davis, shows why a species of tiny worm can learn to ignore an odor - information that could have implications for how human memories are formed.

Scientists have known for decades that sensory neurons - nerves in places like our fingers, ears and eyes - begin the complex task of processing sights, sounds and other stimuli before forwarding the job to the body's mainframe computer: the brain. But just how these neurons accomplish their task has not been well understood.

Now researchers at UC Davis have made a startling discovery: that in olfactory neurons, odor bypasses the normal regulatory pathways in the nucleus and instead boosts synthesis of a protein by acting on RNA, the molecular messengers that typically carry instructions from DNA in the nucleus to protein-building mechanisms in the cell.

Telescope

How did early black holes get so big?

How did black holes lurking at the centre of galaxies like ours get so big so quickly? That's the puzzle posed by the discovery of fully grown, supermassive black holes surrounded by fledgling galaxies early in the history of the universe.

Chris Carilli of the National Radio Astronomy Observatory in Socorro, New Mexico, and colleagues studied four galaxies from less than 2 billion years after the big bang. They found the black holes at the centres of these galaxies were as heavy as anything seen in the modern universe, with one estimated to have the mass of 20 billion suns.

Sun

New Study Resolves Mystery of How Massive Stars Form

Study
© Unknown
Volume renderings of the density field in a region of the simulation at 55,000 years of evolution. The left panel shows a polar view, and the right panel shows an equatorial view. The fingers feeding the equatorial disk are clearly visible.
Theorists have long wondered how massive stars--up to 120 times the mass of the Sun--can form without blowing away the clouds of gas and dust that feed their growth. But the problem turns out to be less mysterious than it once seemed. A study published this week by Science shows how the growth of a massive star can proceed despite outward-flowing radiation pressure that exceeds the gravitational force pulling material inward.

The new findings also explain why massive stars tend to occur in binary or multiple star systems, said lead author Mark Krumholz, an assistant professor of astronomy and astrophysics at the University of California, Santa Cruz. The formation of companion stars emerged unexpectedly from the sophisticated computer simulations the researchers used to explore the physics of massive star formation.

"We didn't set out to solve that question, so it was a nice side benefit of the study," Krumholz said. "The main finding is that radiation pressure does not limit the growth of massive stars."

Palette

UK: Ancient rock art baffles experts

Ancient rock art
© Brian Kerr
No stone unturned: rock art in Northumberland
While some people dream of the warm sun of southern Spain for their retirement, David Jones chose high fells, the sharp teeth of a gale and the quest to find 5,000-year-old artwork. "I decided to build a new life when I retired," says the former IT marketing specialist, as a bitter wind whips through his hair. "I wanted the last third to be quite different from the first two thirds. I walk a lot, I work with charities, and I do this."

"This" is joining more than 100 other Gore-Tex-clad volunteers scouring the moorland of north-east England, searching for traces of the enigmatic and weirdly beautiful carvings our ancestors made on stretches of flat rocks and boulders. The project is a collaboration between English Heritage and Northumberland and Durham County Councils. So far, more than 100 previously unknown carvings have been discovered, featuring a mysterious mix of concentric circles, interlocking rings and hollowed cups. They are broadly dated between 4,000 and 6,000 years old.

Satellite

New Light on Mars Methane Mystery

Mars
© BBC News
The release of methane must be going on now.
Large quantities of methane gas have been detected on Mars, Nasa scientists have announced in Science journal.

The gas could be produced either by geological activity or by life.

Methane was detected in the Martian atmosphere five years ago; scientists have found it is more abundant over particular parts of the planet.

It should last for only a short time in the atmosphere until it is destroyed by sunlight, and so its continued presence means it is being replenished.

Magnify

Mutant Host Cell Protein Sequesters Critical HIV-1 Element

Scientists have identified a new way to inhibit a molecule that is critical for HIV pathogenesis. The research presents a target for development of antiretroviral therapeutics that are likely to complement existing therapies and provide additional protection from HIV and AIDS.

The research is published by Cell Press in the January 16th issue of the journal Molecular Cell.

Infection of human cells with HIV-1 requires multiple events that involve complex interactions between viral elements and cellular proteins. The virus must copy key parts of its DNA as mRNA molecules through a process called transcription. The mRNA molecules must be properly "spliced", or rearranged, and then transported out of the cell nucleus and into the cytoplasm where the mRNAs can be "translated" into viral proteins.

"Although there has been a great deal of effort directed at understanding HIV-1 transcription, mRNA splicing and nuclear export, little is known about the translational control of HIV-1 RNA in the cytoplasm," says senior study author, Dr. Johnny J. He from the Center for AIDS Research at Indiana University School of Medicine.

Blackbox

Our world may be a giant hologram

Image
© Ledomira/Stock.xchng
Could our three dimensions be the ultimate cosmic illusion? A German detector is picking up a hint that we are all mere projections.

Driving through the countryside south of Hanover, it would be easy to miss the GEO600 experiment. From the outside, it doesn't look much: in the corner of a field stands an assortment of boxy temporary buildings, from which two long trenches emerge, at a right angle to each other, covered with corrugated iron. Underneath the metal sheets, however, lies a detector that stretches for 600 metres.

For the past seven years, this German set-up has been looking for gravitational waves - ripples in space-time thrown off by super-dense astronomical objects such as neutron stars and black holes. GEO600 has not detected any gravitational waves so far, but it might inadvertently have made the most important discovery in physics for half a century.

For many months, the GEO600 team-members had been scratching their heads over inexplicable noise that is plaguing their giant detector. Then, out of the blue, a researcher approached them with an explanation. In fact, he had even predicted the noise before he knew they were detecting it. According to Craig Hogan, a physicist at the Fermilab particle physics lab in Batavia, Illinois, GEO600 has stumbled upon the fundamental limit of space-time - the point where space-time stops behaving like the smooth continuum Einstein described and instead dissolves into "grains", just as a newspaper photograph dissolves into dots as you zoom in. "It looks like GEO600 is being buffeted by the microscopic quantum convulsions of space-time," says Hogan.

Magnify

Study Shows How Defective DNA Repair Triggers 2 Neurological Diseases

Scientists at St. Jude Children's Research Hospital have teased apart the biological details distinguishing two related neurological diseases - ataxia telangiectasia-like disease (ATLD) and Nijmegen breakage syndrome (NBS).

Both disorders arise from defects in a central component of the cell's machinery that repairs damaged DNA, but each disease presents with distinct pathologies. Defects in DNA repair dramatically increase the risk of cancer, which is found in NBS. However, NBS is also characterized by the occurrence of small brain size, or microcephaly, while in contrast, ATLD causes predominantly neurodegeneration.

The research involved the use of mouse models of each the diseases to analyze how the gene defects in ATLD and NBS give rise to the different pathologies. The researchers published their findings in the Jan.15, 2009, issue of the journal Genes & Development.