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A study on ash blasted from volcanoes is a first step towards accurately assessing where it is safe to fly during eruptions, according to the authors. The researchers found that the ash grains ejected into the atmosphere have diverse shapes and properties. They also learned that big grains can travel further than was previously estimated. All this could improve existing models of ash concentrations, which governments and airlines use to make flight decisions during eruptions, they say. Ash can cause aircraft engines to fail.

The first grid-connected wave energy device in North American waters started feeding renewable electricity to a Marine Corps base in Hawaii last week. In coordination with the U.S. Navy, Northwest Energy Innovations and the Energy Department brought online a prototype of the Azura wave energy converter (WEC) device. The one-of-a-kind, wave energy device is designed to generate electricity from the motion of the choppy waters at the Navy’s Wave Energy Test Site (WETS) in Kaneohe Bay on Oahu. 

Having a hierarchical social structure with just a few well-connected leaders enables pigeon flocks to navigate more accurately on the wing, new research shows.

Hierarchical organisation also enables flocks to cope better with navigation errors made by individual birds.

Researchers from Oxford University and the Zoological Society of London created 'virtual flocks' of homing pigeons to test how different social networks affect the navigation performance of these groups. The team's simulations looked at everything from no networks (all connections between individuals were of equal strength) to random networks (some connections were stronger than others but randomly distributed) to hierarchical networks with just a few well-connected individuals leading the way.

Evolutionary theorist Stephen Jay Gould is famous for describing the evolution of humans and other conscious beings as a chance accident of history. If we could go back millions of years and "run the tape of life again," he mused, evolution would follow a different path. 

A study by University of Pennsylvania biologists now provides evidence Gould was correct, at the molecular level: Evolution is both unpredictable and irreversible. Using simulations of an evolving protein, they show that the genetic mutations that are accepted by evolution are typically dependent on mutations that came before, and the mutations that are accepted become increasingly difficult to reverse as time goes on.

Este estudio, realizado por ingenieros de la Universidad de Sheffield, es el primero en demostrar, de manera concluyente, que los contaminantes pueden entrar en las tuberías a través de filtraciones y ser transportado a través de la red de tuberías.

La presión en las tuberías de agua generalmente obliga al agua a salir través de las fugas, previniendo que cualquier otra cosa entre al sistema. Pero cuando hay una caída de presión...