When a flow reaches a certain speed, things get turbulent: The fluid or the gas no longer flows in an orderly fashion but whirls around wildly.  

Turbulent flows in pipes are of importance for many every-day applications. What they all have in common is their appearance: They travel down the pipe bubbling and gurgling like a mountain stream. The flow only calms down when its speed is reduced. Scientists call this calmer state laminar. Crucial for the difference between laminar and turbulent flow are the inner forces that link the water molecule to each other. Only if the influence of these inner forces is smaller than the influence of the forces that accelerate the flow can turbulence appear.

Slow-moving ocean and river currents could be a new, reliable and affordable alternative energy source. A University of Michigan engineer has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power.

The machine is called VIVACE. A paper on it is published in the current issue of the quarterly Journal of Offshore Mechanics and Arctic Engineering.

VIVACE is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth's currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.

Cordiality and mutually beneficial arrangements can be more important than hard-negotiated deals when it comes to cementing strong working relationships among supply chain partners, according to the Management Insights feature in the current issue of Management Science. 

In their study, the authors observe that people's actions in economic transactions are motivated by more than incentives. 

Incentives, say the authors, can cause people to be calculating rather than oriented toward a win-win. Behavior is also influenced emotionally by social preferences. In particular, people care about status ("how much do I have relative to you?") and reciprocity ("if you were nice to me, I want to reciprocate; if you were not nice, I want to retaliate"). 

It is said that timing is everything, and that certainly appears to be true for autumn infants. Children who are born four months before the height of cold and flu season have a greater risk of developing childhood asthma than children born at any other time of year, according to new research. 

The study analyzed the birth and medical records of more than 95,000 children and their mothers in Tennessee to determine whether date of birth in relationship to the peak in winter respiratory viruses posed a higher risk for developing early childhood asthma. They found that while having clinically significant bronchiolitis at any age during infancy was associated with an increased risk of childhood asthma, for autumn babies, that risk was the greatest. 

Scientists writing in PLoS Pathogens have reported the discovery of a new species of Ebola virus, provisionally named Bundibugyo ebolavirus. The virus, which was responsible for a hemorrhagic fever outbreak in western Uganda in 2007, has been characterized by a team of researchers from the Centers for Disease Control and Prevention in Atlanta, Georgia the Uganda Virus Research Institute; the Uganda Ministry of Health; and Columbia University.

A course of organised water aerobics has been shown to reduce the amount of pain-killing medication women request during labor. Research published in the journal Reproductive Health has shown that, as well as being safe, the gentle exercise has the benefit of making it easier to give birth.