The first direct evidence of how and when tectonic plates move into the deepest reaches of the Earth is published in Nature. Scientists hope their description of how plates collide with one sliding below the other into the rocky mantle could potentially improve their ability to assess earthquake risks. Contrary to common scientific predictions, dense plates tend to be held in the upper mantle, while younger and lighter plates sink more readily into the lower mantle.

  Pregnant women who suffer from the high risk condition pre-eclampsia -- which leads to the death of hundreds of babies every year -- are putting the lives of their unborn children at significantly increased risk if they continue to smoke during pregnancy.

  Although it's too soon to sound the death knell for the "senior moment," it appears that memory loss and thinking problems are becoming less common among older Americans. A new nationally representative study shows a downward trend in the rate of "cognitive impairment" -- the umbrella term for everything from significant memory loss to dementia and Alzheimer's disease -- among people aged 70 and older. The prevalence of cognitive impairment in this age group went down by 3.5 percentage points between 1993 and 2002 -- from 12.2 percent to 8.7 percent, representing a difference of hundreds of thousands of people.

  Researchers have developed the first animal model of the infection caused by chikungunya virus, an emerging arbovirus associated with large-scale epidemics. Using this mouse model scientists determined which tissues and cells are infected by the virus in both the mild and severe forms of the disease it causes.

  Earth scientists have found that carbon dioxide has been naturally stored for more than a million years in several gas fields in the Colorado Plateau and Rocky Mountains of the United States. Researchers say lessons learned from these natural gas fields will help to find sites suitable for injecting carbon dioxide captured from power station chimneys.

  A study conducted on 346 19-month-old twins reveals that the genetic and environmental bases of hormonal response to stress depend on the context in which a child grows up. This is the first time such an effect has been reported in young humans.

  As oceans warm and become more acidic, ocean creatures are undergoing severe stress and entire food webs are at risk, according to molecular ecologists. Biologists have just returned from a research mission to Antarctica where they collected pteropods, tiny marine snails the size of a lentil, that one biologist refers to as the "potato chip" of the oceans because they are eaten widely by so many species.

  New compounds with the potential for antidepressant activity have been found. A chemist has synthesized new molecules which affect two brain targets which are considered to be keys in the development of processes of depression. One of these is the serotonin transporter, whose reuptake reduction has already been shown to improve mood; the other is the serotoninergic receptor 5-HT7, a therapeutic target for serotonin whose modulation can provoke anti-depressant effects.

  A better understanding of how memory works is emerging from a newfound ability to link a learning experience in a mouse to consequent changes in the inner workings of its neurons. Researchers have developed a way to pinpoint the specific cellular components that sustain a specific memory in genetically engineered mice. Remarkably, this research demonstrates a way to untangle precisely which cells and connections are activated by a particular memory, according to researchers.

  Scientists have found new evidence, using innovative techniques, to support the growing body of literature that indicates kava may have a negative effect on the liver. Kava is a plant native to the South Pacific that has been used as a ceremonial beverage in the region for thousands of years, and, more recently, as a natural treatment for medical conditions such as anxiety. In recent years, serious concerns about the dangers of kava and the effects on the liver have resulted in regulatory agencies, such as the US Food and Drug Administration and Australia's Therapeutic Goods Administration, banning or restricting the sale of kava and kava products.

  The world's sharks are disappearing. These fearsome yet charismatic fish continue to fall victim to overfishing and many are now at risk of extinction as a result. New research shows that open-ocean sharks are particularly threatened from overfishing, and other work shows that the deeper sharks live, the longer it takes for their populations to recover. Yet researchers are just now learning critical details of their behavior, including the fact that some species migrate quickly along "superhighway" routes and congregate at established "stepping stone" sites.

  Premature birth can have serious effects on the development and growth of children. In many parts of the world, preterm deliveries are increasing in frequency. In a study in the American Journal of Obstetrics &Gynecology, researchers found that there was a strong link between physical abuse during pregnancy and premature births.

  An enormous plume of dust and water spurts violently into space from the south pole of Enceladus, Saturn's sixth-largest moon. This raging eruption has intrigued scientists ever since the Cassini spacecraft provided dramatic images of the phenomenon. Now a physicist has revealed why the dust particles in the plume emerge more slowly than the water vapour escaping from the moon's icy crust. Enceladus orbits in Saturn's outermost "E" ring. It is one of only three outer solar system bodies that produce active eruptions of dust and water vapour. Moreover, aside from the Earth, Mars, and Jupiter's moon Europa, it is one of the only places in the solar system for which astronomers have direct evidence of the presence of water.

  New techniques for detecting emboli (harmful blood clots/air bubbles in arteries) have played a major role in dramatically reducing stroke rates after carotid endarterectomy. This is an operation designed to remove narrowings in the main arteries supplying the brain before they can cause a stroke. Before per-operative embolus monitoring was introduced in 1992, the intra-operative stroke rate during carotid artery procedures was 4%. Today it is 0.2%. Before post-operative monitoring was introduced in 1995, the post-operative stroke rate was 2.7%. Today it is extremely rare.