When flowering plants are surrounded by a large number of insects, usually both sides profit from the encounter. Feasting on the plant juice and pollen, the insects pollinate the flowers and thus secure the survival of the plants. However, sometimes the insects - in this case a certain species of leafhoppers - can bring disaster to the plants, which they are not able to overcome. 

Climate variability is one of the major forces in the rise and fall of agrarian states in Mexico and Peru, according to a team of researchers looking at both climate and archaeological records.

"We are arguing that the climate information in both areas is good enough to establish that climate is playing some role in the rise and fall of these city states," said Douglas Kennett, professor of environmental archaeology. "Now we need to further refine the archaeological data."

REM sleep, the phase of night-time mammalian sleep physiology where dreams occur, has long fascinated scientists, clinicians, philosophers, and artists alike, but the identity of the neurons that control REM sleep, and its function in sleep have been controversial due to a lack of precise genetic methods to study the sleeping brain.

A demonstration of a recent brain technology provides the first answers to both questions, identifying a neural circuit in the brain that regulates REM sleep, and showing that REM sleep controls the physiology of the other major sleep phase, called non-REM (NREM) sleep.

Within modern cosmology, the Big Bang marks the beginning of the universe and the creation of matter, space and time about 13.8 billion years ago. Since then, the visible structures of the cosmos have developed: billions of galaxies which bind gas, dust, stars and planets with gravity and host supermassive black holes in their centres. But how could these visible structures have formed from the universe's initial conditions?

To answer this question, theoretical astrophysicists carry out cosmological simulations. They transform their knowledge about the physical processes forming our universe into mathematical models and simulate the evolution of our universe on high-performance computers over billions of years.

WASHINGTON, DC - Researchers at a Dallas children's hospital aim to show that nonpowder firearms such as airsoft, BB, and paintball guns should not be viewed as toys, but rather powerful weapons causing increasingly severe and sometimes life-threatening injuries in pediatric patients.

For hundreds of millions of people around the world, chewing betel nut produces a cheap, quick high but also raises the risk of addiction and oral cancer.

The betel nut, a seed of the areca palm, is grown and used throughout India, parts of China and much of Southeast Asia, including Indonesia and most of the Pacific islands. Chewing the betel quid -- a mixture of areca nut, spices and slaked lime wrapped in betel vine leaves -- has been a cultural tradition in those regions for centuries. In small doses, it creates a sense of euphoria and alertness. Prolonged use can create addiction and the World Health Organization classifies the betel nut as a carcinogen.