Science Sunday: Wrap-up of recent advancements in science from EurekAlert!

Researchers identify neurons that assign value during learning:

By using an experimental trick to activate certain sets of neurons and effectively substitute activation of these cells for positive or negative experiences, researchers have been able to identify neurons in the fruit fly Drosophila that are responsible for assigning value to stimuli during so-called associative learning.

Anticipation plays a powerful role in human memory, brain study finds:

Psychologists have long known that memories of disturbing emotional events -- such as an act of violence or the unexpected death of a loved one -- are more vivid and deeply imprinted in the brain than mundane recollections of everyday matters.

Organic semiconductors make cheap, flexible photovoltaics and LEDs:

Cornell University researchers have demonstrated a new type of organic semiconductor device using ionic junctions which shows electroluminescence and acts as a photovoltaic cell. The idea could lead to displays on cloth or paper and very inexpensive solar cells.

Nanoscientists create biological switch from spinach molecule:

Nanoscientists have transformed a molecule of chlorophyll-a from spinach into a complex biological switch that has possible future applications for green energy, technology and medicine.

Edible coatings will be the packaging of the future:

One of the most popular alternatives in the last few years is the edible coating - a transparent film that covers the food item and acts as a barrier to humidity and oxygen. Moreover, these films can be used as a host for additives in the conservation of the properties of the product or simply in order to improve its appearance. This was the subject of the PhD thesis by Navarre chemist, Javier Osés Fernández, at the Public University of Navarre.

Genetic surprise confirms neglected 70-year-old evolutionary hypothesis:

Biologists at the University of Rochester have discovered that an old and relatively unpopular theory about how a single species can split in two turns out to be accurate after all, and acting in nature. The finding, reported in today's issue of Science, reveals that scientists must reassess the forces involved in the origin of species. The beginnings of speciation, suggests the paper, can be triggered by genes that change their locations in a genome.

Dark matter 'proof' called into doubt:

When a researcher from the University of Arizona in Tucson announced on August 21 that his team had "direct proof of dark matter's existence," it seemed the issue had been settled. Now proponents of alternative theories of gravity, who explain the motion of stars and galaxies without resorting to dark matter, have hit back and are suggesting that the conclusion was premature.

'World's smallest controlled heat source' studies explosives at the nanoscale:

Using nanometer scale analysis techniques and quantities too small to explode, researchers have mapped the temperature and length-sale factors that make energetic materials - otherwise known as explosives - behave the way they do.

'Allergy cells' can aggravate cancer and psoriasis:

The body's mast cells are mainly associated with allergic reaction in the way they release histamine and other inflammatory substances. However, researchers at Karolinska Institute have now demonstrated how the mast cells can also contribute to diseases like psoriasis and cancer.

MIT uses sound to search for gas, oil:

Just as doctors use ultrasound to image unborn babies, MIT researchers listen to the echoing language of rocks to map what's going on tens of thousands of feet below the Earth's surface. Now the scientists will use their skills to find pockets of natural gas and oil contained in fractured porous rocks in a Wyoming oil field. If the method proves effective, it could be used at oil and gas fields across the country.

Researcher lights the way to better drug delivery:

A Purdue University researcher has explained for the first time the details of how drugs are released within a cancer cell, improving the ability to deliver drugs to a specific target without affecting surrounding cells. The understanding of how to deliver and unload a cancer drug can be extrapolated to all sorts of other diseased cells.

Need to pull an all-nighter?:

People who must ward off sleep -- soldiers, pilots, truckers, students, doctors, parents of newborns -- might someday benefit from drugs that prevent nitric oxide gas from building up in the brain. New research finds that nitric oxide accumulation in the brain's basal forebrain is both necessary and sufficient to produce sleep, providing a completely new basis for developing drugs that help people stay awake -- or, conversely, sleep.

Study illuminates how the plague bacteria causes disease:

The bacteria responsible for the plague and some forms of food poisoning "paralyze" the immune system of their hosts in an unexpected way, according to a new study in the Sept. 8, 2006, issue of the journal Cell, published by Cell Press.

Physicists trap, map tiny magnetic vortex:

In a research first that could lead to a new generation of hard drives capable of storing thousands of movies per square inch, physicists at Rice University have decoded the three-dimensional structure of a tornado-like magnetic vortex no larger than a red blood cell. The findings, published online by Physics Review Letters, were made with a one-of-a-kind scanning ion microscope that trapped and imaged cone-like magnetic vortices on tiny cobalt disks.

Earth-like planets may be more common than once thought, says new U. of Colorado-Penn State study:

More than one-third of the giant planet systems recently detected outside Earth's solar system may harbor Earth-like planets, many covered in deep oceans with potential for life, according to a new study led by the University of Colorado at Boulder and Pennsylvania State University.