Army ants build living bridges by linking their bodies to span gaps and create shortcuts across rainforests in Central and South America. An international team of researchers has now discovered these bridges can move from their original building point to span large gaps and change position as required.

The bridges stop moving when they become so long that the increasing costs incurred by locking workers into the structure outweigh the benefit that the colony gains from further shortening their trail. Bridges dismantle when the ants in the structure sense the traffic walking over them slows down below a critical threshold.

A new analysis led by the Johns Hopkins Bloomberg School of Public Health suggests that while most U.S. health insurance plans deny benefits to transgender men and women for medical care necessary to transition to the opposite sex, paying for sex reassignment surgery and hormones is actually cost-effective.

How does the price impact your evaluation of a restaurant meal?

Psychologists have long believed that we judge experiences based on their most intense moment (the peak) and the last part of the experience (end). But that can change dramatically depending on how much customers are paying for the experience., according to a new paper which investigated how the price of pizza changed the relationship between a consumer's overall evaluation of the meal and the evaluation of each individual slice of pizza.

An international team of astrophysicists led by a Johns Hopkins University scientist has for the first time witnessed a star being swallowed by a black hole and ejecting a flare of matter moving at nearly the speed of light.

The finding reported Thursday in the journal Science tracks the star -- about the size of our sun -- as it shifts from its customary path, slips into the gravitational pull of a supermassive black hole and is sucked in, said Sjoert van Velzen, a Hubble fellow at Johns Hopkins.

"These events are extremely rare," van Velzen said. "It's the first time we see everything from the stellar destruction followed by the launch of a conical outflow, also called a jet, and we watched it unfold over several months."

Scientists have developed a new method to model heat wave magnitude that takes both the duration and the intensity of the heat wave into account.

The new metric--the Heat Wave Magnitude Index daily (HWMId)--indicates that a little-studied heat wave in Finland in 1972 had the same extent and magnitude of the 2003 European heat wave that is considered the second strongest heat wave since 1950.

The findings are published today, 27th November 2015, in the journal Environmental Research Letters.

New research finds that progesterone supplements in the first trimester of pregnancy do not improve outcomes in women with a history of unexplained recurrent miscarriages.

The study of 826 women with previously unexplained recurrent miscarriage showed that those who received progesterone treatment in early pregnancy were no less likely to miscarry than those who received a placebo. This was true whatever their age, ethnicity, medical history and pregnancy history.