A new metal matrix composite that is so light that it can float on water, so a boat made of it would not sink despite damage to its structure - and this syntactic foam has good heat resistance too.

Syntactic foams have been around for many years but this is the first lightweight metal matrix syntactic foam, say the researchers from Deep Springs Technology (DST) and the New York University Polytechnic School of Engineering.

Their magnesium alloy matrix composite is reinforced with silicon carbide hollow particles and has a density of only 0.92 grams per cubic centimeter compared to 1.0 g/cc of water. Not only does it have a density lower than that of water, it is strong enough to withstand the rigorous conditions faced in the marine environment.

It's been known since the 16th century that neurons and blood vessels often traverse the body side by side but it was only more recently discovered that the growth of neuronal and vascular networks is controlled by the same molecules. 

“Most interesting is the interaction between neurons and blood vessels in the cerebral cortex. To date, we know very little about how neurons communicate with endothelial cells in order to structure a functional network in the brain.” explains Prof. Dr. Amparo Acker-Palmer, who plans to assess these processes in the layering of the cerebral cortex during embryonic development.

When ants go exploring in search of food they end up choosing collective routes that fit statistical distributions of probability, according to a team of mathematicians who analyzed the trails of a species of Argentine ant. 

It's unknown how flocks of birds, shoals of fish, lines of ants and other complex natural systems organize themselves so well when moving collectively so researchers from Spain and the U.S. analyzed the movements of Argentine ants (Linepithema humile, an invasive species in many parts of the world) while they forage or explore an empty space (a petri dish) and then they proposed a model explaining how they form their routes.

During the short, dreary days of winter, some people feel tired and oversleep, they are depressed and irritable and have trouble concentrating.  But once spring arrives, they say they feel fine.

4 percent of the American public say they suffer from this seasonal affective disorder (SAD), a type of depression that occurs during the same season each year.

Biologists know that variations in the amount of sunlight a person receives and her or his circadian clock play a role in the disorder and some have proposed that the neurotransmitters serotonin and melatonin may be involved. However, they have not yet identified the underlying neurobiological mechanisms responsible.

Kids from
multilingual environments
become better communicators, according to a new paper in 
Psychological Science
which says that such children are better at interpreting a speaker's meaning than children who are exposed only to their native tongue - even if the kids are not bilingual themselves.

Exposure to more than one language is the key for building effective social communication skills, says University of Chicago Katherine Kinzler, who believes this paper is the first to demonstrate the social benefits of just being exposed to multiple languages. 

"It takes a village to raise a child" is folk wisdom which means that quality communities turn out quality individuals.

It may have seemed like a new idea when First Lady Hillary Clinton said it in the 1990s but ancient societies formed cooperative groups to help raise their children. Why did that happen?

University of Utah anthropologist Karen Kramer and colleagues created an economic model where mothers had one dependent offspring at a time, ended support of their young at weaning and received no help from others and then mapped it to where mothers often have multiple kids who help rear other children.