One in five cases of Lassa fever - a disease that kills around 5,000 people a year in West Africa - could be due to human-to-human transmission, with a large proportion of these cases caused by 'super-spreaders', according to a new paper.

Between 2006 and 2012 in the U.S., there was a decline in rates of episiotomy, a surgical procedure for widening the outlet of the birth canal to make it easier for the mother to give birth, according to a study in the January 13 issue of JAMA.

Episiotomy is a common obstetric procedure, estimated to be performed in 25 percent of vaginal deliveries in the United States in 2004. Restrictive use of episiotomy has been recommended given the risks of the procedure and unclear benefits of routine use. Decreasing use of the procedure was documented in the 1990s; however, whether rates have continued to decrease after evidencebased recommendations has not been known, according to background information in the article.

Scientists have gained new insight into fragile X syndrome, the most common cause of inherited intellectual disability, by studying the case of a person without the disorder, but with two of its classic symptoms.

Fragile X syndrome results from an inherited genetic error in a gene called FMR1. The error prevents the manufacture of a protein called FMRP. Loss of FMRP is known to affect how cells in the brain receive signals, dialing up the amount of information allowed in. The gene is on the X chromosome, so the syndrome affects males more often and more severely than females, who may be able to compensate for the genetic error if their second copy of FMR1 is normal.

Every summer, there are reports linking a bacterium called Vibrio vulnificus to people getting sick or dying. The bacteria are found in warm saltwater and problems occur after eating raw tainted shellfish or when an open wound comes in contact with seawater.

People with a weakened immune system, chronic liver disease or iron overload disease are most at risk for severe illness. Vibrio vulnificus infections in high-risk individuals are fatal 50 percent of the time.

Living systems have the ability to produce collective molecular motions that have an effect at the macroscale, such as a muscle that contracts via the concerted action of protein motors. In order to reproduce this phenomenon, a team at CNRS's Institut Charles Sadron led by Nicolas Giuseppone, professor at the Université de Strasbourg, has made a polymer gel that is able to contract through the action of artificial molecular motors. When activated by light, these nanoscale motors twist the polymer chains in the gel, which as a result contracts by several centimeters.

Another advantage is that the new material is able to store the light energy absorbed.

The amount of time children spend using screens, such as televisions and computers, on a daily basis exceeds recommended guidelines but those guidelines were drawn up at a time when tablets, cell phones and other mobile devices were not as present in everyday life. Unless you are Amish or a doomsday prepper, it is unlikely that the future will mean current screen time guidelines.

And how valid are they anyway? Yes, prolonged use of screens by children is associated with adverse physical and mental health outcomes, such as increased risk of depression and anxiety in adolescent girls, but that is epidemiological curve fitting based on surveys, not real data.