Neural stem cells normally go with the flow of chemical guides. But with a little electrical stimulation they can be coaxed to go the other way, a new study shows.

When scientists applied electric current to human neural stem cells injected into rats' brains, the cells moved toward the animals' subventricular zone and lateral ventricle, instead of toward their olfactory bulb, the default destination. The result, published June 29 in Stem Cell Reports, suggests that electrical stimulation could one day be used to guide neural stem cells to damaged sites in the brain.

"This is the first study I've seen where stimulation is done with electrodes in the brain and has been convincing about changing the natural flow of cells so they move in the opposite direction," stem cell expert Alan Trounson of the Hudson Institute in Australia tells The Scientist. "The technique has strong possibilities for applications because the team has shown you can move cells, and you could potentially move them into seriously affected brain areas."

"I didn't expect the direction of the cells could be reversed," study coauthor Min Zhao of the University of California, Davis, tells The Scientist. The molecules that direct the flow of cells in the brain are very commanding, he says. Seeing that electrical stimulation can reverse the directions the cells travel shows the technique is "even more powerful than we thought" for guiding neural stem cells.

A virus that invaded the genomes of humanity's ancestors millions of years ago now plays a critical role in the embryonic stem cells from which all cells in the human body derive, new research shows.

The discovery sheds light on the role viruses play in human evolution and could help scientists better understand how to use stem cells in advanced therapies or even how to convert normal cells into stem cells.

Embryonic stem cells are pluripotent, meaning they are capable of becoming any other kind of cell in the body. Scientists around the world hope to use this capability to help patients recover from injury and disease.

Researchers have struggled for decades to figure out how pluripotency works. These new findings reveal that "material from viruses is vital in making human embryonic stem cells what they are," said computational biologist Guillaume Bourque at McGill University in Montreal, a co-author of the study published online March 30 in Nature Structural & Molecular Biology.

A fifth of male fish are now transgender because of chemicals from the contraceptive pill being flushed down household drains, a study by has suggested.

Male river fish are displaying feminised traits and even producing eggs, the study found. Some have reduced sperm quality and display less aggressive and competitive behaviour, which makes them less likely to breed successfully.

The chemicals causing these effects include ingredients in the contraceptive pill, by-products of cleaning agents, plastics and cosmetics, according to the findings.

Professor Charles Tyler, of the University of Exeter, is to present his findings in a key-note lecture at a symposium this week. He will explain that the offspring of such "transgender" or "intersex" fish can also be more sensitive to the effects of these chemicals in subsequent exposures.

Along the wild Pacific coast of British Columbia, there lives a population of the sea wolves. "We know from exhaustive DNA studies that these wolves are genetically distinct from their continental kin," says McAllister. "They are behaviourally distinct, swimming from island to island and preying on sea animals. They are also morphologically distinct — they are smaller in size and physically different from their mainland counterparts," says Ian McAllister, an award-winning photographer who has been studying these animals for almost two decades.

McAllister captured the magic of these wolves in breath-taking pictures. As he swam towards them, "the curious canines approached him so closely that he could hear them grunting into his snorkel. He took several frames, then pushed back into deeper water without daring to look up," writes the bioGraphic.

Humanity could face one less doomsday scenario if NASA has its way.

On Friday, the space agency announced plans to redirect the course of a small asteroid approaching Earth, as part of the Double Asteroid Redirection Test (DART), according to a NASA press release.

The release notes that asteroids hit Earth nearly every day, but most are small enough to burn up in the atmosphere.

But the DART project -- a joint effort between NASA and the John Hopkins Applied Physics Laboratory in Maryland -- is for the asteroids that are too big to break up -- those that could have severe consequences for the Earth if they hit.

"DART would be NASA's first mission to demonstrate what's known as the kinetic impactor technique -- striking the asteroid to shift its orbit -- to defend against a potential future asteroid impact," said Lindley Johnson, NASA's planetary defense officer in Washington, in the press release.

"This approval step advances the project toward an historic test with a non-threatening small asteroid."

An unprecedented number of particles has been reached in record time. Just five weeks after physics resumed, the Large Hadron Collider (LHC) is already running at full throttle. On Wednesday 28 June 2017 the LHC established yet another record-breaking high, with 2556 proton bunches circulating in each direction of the accelerator.

The beams in the LHC are made up of bunches of protons, spaced seven metres (25 nanoseconds) apart, with each one containing more than 100 billion protons. 2556 is the maximum possible number of bunches that can be reached with the beam preparation method currently used.

The particle bunches that are delivered to the LHC are prepared and accelerated by a chain of four accelerators. Since last year, a new method to group and split the bunches enables the particles to be squeezed even closer together. With an equal number of protons, the beam diameter was reduced by 40 per cent. Denser bunches means a higher probability of collisions at the centre of the experiments.

The lifespan of NASA's Cassini is coming to an end, but in one of its final acts the space probe has captured images of an incredible vortex that experts believe has been raging on Saturn for centuries.

In 1981, the US space agency's Voyager 2 spacecraft discovered a mass of clouds on the north pole of the gas giant that appeared to be permanently swirling.

Scientists pursue research through observation, experimentation and modeling. They strive for all of these pieces to fit together, but sometimes finding the unexpected is even more exciting. That's what happened to University of Central Florida's astrophysicist Gal Sarid, who studies comets, asteroids and planetary formation and earlier this year was part of a team that published a study focused on the comet 174P/Echeclus. It didn't behave the way the team was expecting.

"This is another clue that Echeclus is a bizarre solar system object," said University of South Florida physics research Professor Maria Womack, who leads the team.

Comets streak across the sky and as they get closer to the sun look like bright fuzz balls with extended luminous trails in their wake. However, comets are actually bulky spheres of mixed ice and rock, many of them also rich in other frozen volatile compounds, such as carbon monoxide, carbon dioxide, hydrogen cyanide and methanol.

Comets heat up as they get closer to the sun, losing their icy layers by sublimation and producing emission jets of water vapor, other gases and dust expelled from the comet nucleus, Sarid said. Once they move away from the sun, they cool off again. But some comets start showing emission activity while still very far from the sun, where heating is low.

Two retired army veterans who lost their arms more than 40 years ago have received revolutionary prosthetic limbs developed by the Pentagon. Their new futuristic arms, which are named after Luke Skywalker, can pick up small objects as fragile as an egg.

"Stirring with this, I'm cutting with that, dicing," Fred Downs said, as cited by CBS news. Downs lost his left arm below the elbow after being injured in the Vietnam War.

"It's the fun part of being able to use two hands to get all the vegetables prepared, and the meat prepared, and start the grill, and hold plates," he continued.

The second recipient, Artie McAuley, a retired Army captain who lost his left arm in a car accident, was also thrilled to receive his new limb. In order to lift the arm, an amputee has to lift his foot. Sensors in the wearer's shoes then pick up the motion and put the prosthetic limb into action.

"You have to be smart to do this," McAuley said, as cited by AFP. "Once in a while, I make a mistake!"

Electronic devices that harness the power of brain signals are one of the latest additions to the world of gaming. A new study has found, however, that hackers could also use such technology to access private information such as passwords and ATM pin codes.

A study by researchers at the University of Alabama at Birmingham has provided an example of how devices that operate using brain signal monitoring, like electroencephalography (EEG), may be a future tool for cyber thieves.

Using two EEG headsets, one clinical and the other a commercial product available to consumers, lead researcher professor Nitesh Saxena was able to devise a way to eavesdrop on people's neural signals.

The study details an attack strategy known as PEEP, described as an advanced type of keylogging, where hackers surreptitiously record via a virus, or determine through sound analysis, strokes on a keyboard.