Researchers have discovered the mechanism behind one of the Ebola virus' most dangerous attributes: its ability to disarm the adaptive immune system.

University of Texas Medical Branch at Galveston scientists determined that Ebola short-circuits the immune system using proteins that work together to shut down cellular signaling related to interferon. Disruption of this activity, the researchers found, allows Ebola to prevent the full development of dendritic cells that would otherwise trigger an immune response to the virus.

"Dendritic cells typically undergo a process called 'maturation' when they're infected by a virus - they change shape and present antigens on their surface that tell T-cells to attack that particular virus, thus generating an adaptive immune response," said UTMB professor Alexander Bukreyev, senior author of a paper on the discovery now online in the Journal of Virology. "But Ebola prevents dendritic-cell maturation and produces a severe infection without an effective adaptive immune response. We found that its ability to do this depends on several specific regions of two different proteins."

Bukreyev's research group made the discovery after a series of procedures that started with a clone of the Ebola Zaire virus strain. Working under maximum-containment conditions in a biosafety level 4 facility in UTMB's Galveston National Laboratory, the team introduced mutations into the virus' genetic code at four locations thought to generate proteins that affected immune response.

The speed of light is constant, or so textbooks say. But some scientists are exploring the possibility that this cosmic speed limit changes, a consequence of the nature of the vacuum of space.

The definition of the speed of light has some broader implications for fields such as cosmology and astronomy, which assume a stable velocity for light over time. For instance, the speed of light comes up when measuring the fine structure constant (alpha), which defines the strength of the electromagnetic force. And a varying light speed would change the strengths of molecular bonds and the density of nuclear matter itself.

A non-constant speed of light could mean that estimates of the size of the universe might be off. (Unfortunately, it won't necessarily mean we can travel faster than light, because the effects of physics theories such as relativity are a consequence of light's velocity). [ 10 Implications of Faster-Than-Light Travel ]

In culmination of a decade's work, RoboBees achieve vertical takeoff, hovering, and steering

Last summer, in a Harvard robotics laboratory, an insect took flight. Half the size of a paper clip, weighing less than a tenth of a gram, it leapt a few inches, hovered for a moment on fragile, flapping wings, and then sped along a preset route through the air.

Like a proud parent watching a child take its first steps, graduate student Pakpong Chirarattananon immediately captured a video of the fledgling and emailed it to his adviser and colleagues at 3 a.m. - subject line: "Flight of the RoboBee."

"I was so excited, I couldn't sleep," recalls Chirarattananon, co-lead author of a paper published this week in Science.

The demonstration of the first controlled flight of an insect-sized robot is the culmination of more than a decade's work, led by researchers at the Harvard School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard.

The United Nations Human Rights Council (UNHRC) has called for a global freeze on the use of drones as the US killer drone strikes continue to take innocent lives in several countries.

The UNHRC report published on May 2 seeks a moratorium on the "testing, production, assembly, transfer, acquisition, deployment and use" of fully or semi-autonomous weapons including drones and robots until an international forum can establish rules for their use. The use of drones violates international law, the report stated.

Christof Heyns, a South African professor of human rights law and author of the report, said the United States, the UK and the Israeli regime in particular have developed killer robots dubbed Lethal Autonomous Robotics (LAR) that can attack targets without any human input.

Here's a new image of Comet C/2012 S1 ISON, as seen on May 1, 2013 by Ernesto Guido and Nick Howes of the Remanzacco Observatory. They used the 2 meter La Palma Telescope. Their initial approximation of the tail length is around 28 arcseconds, which Howes told Universe Today is bigger than some recent reports from smaller scopes.

As of May 2, Comet ISON was approximately 3.885 AU from the Sun, which is about 581 million kilometers (361 million miles) distant from the Sun. ISON will makes its close approach to the Sun when it passes within 1.2 million km (730,000 miles) of the Sun on November 28, 2013.

In the next five years or so, scientists are poised to discover proof that space and time can wrinkle in the form of gravitational waves. These waves were predicted almost 100 years ago by Albert Einstein's general theory of relativity, but have yet to be seen.

That could change soon when the latest, most sensitive experiments hunting gravitational waves come online. "There's so much activity and excitement in the field right now," said Mansi M. Kasliwal, an astronomer at the Observatories of the Carnegie Institution for Science in Pasadena, Calif. "The momentum is really building."

Kasliwal is the author of a paper published online today (May 2) in the journal Science describing the burgeoning field of gravitational wave studies.

According to general relativity, massive objects warp space and time around them, like a bowling ball dropped onto a sheet of rubber, causing passing objects, and even light, to travel along curved paths.

When two extremely dense objects, such as neutron stars (stars so dense the protons and electrons in their atoms collapse to form neutrons) or black holes, orbit each other in binary pairs, their interactions should create ripples in the fabric of space-time called gravitational waves. The most powerful waves would arise when two neutron stars or black holes merge together.

The oldest known hip from a great ape is now shedding light on the evolution of hominids, revealing the ancient creature may have adopted the upright posture often linked with humans and living great apes, researchers say.

Scientists discovered the fossil skeleton of an ape near Barcelona in Catalonia in northeastern Spain in 2002, when a bulldozer was clearing the land for digging. They named it Pierolapithecus catalaunicus, or the ape from near the village of Els Hostalets de Pierola in Catalonia.

The researchers estimate the ape lived about 11.9 million years ago. Analysis of its skeleton and teeth suggest it was male, weighed about 77 lbs. (35 kilograms) and dined on fruit.

The 1908 explosion over the Tunguska region in Siberia has always been an enigma. While the leading theories of what caused the mid-air explosion are that an asteroid or comet shattered in an airburst event, no reliable trace of such a body has ever been found. But a newly published paper reveals three different potential meteorite fragments found in the sandbars in a body of water in the area, the Khushmo River. While the fragments have all the earmarks of being meteorites from the event - which could potentially solve the 100-year old mystery - the only oddity is that the researcher actually found the fragments 25 years ago, and only recently has published his findings.

Like the recent Chelyabinsk airburst event, the Tunguska event likely also produced a shower of fragments from the exploding parent body, scientists have thought. But no convincing evidence has ever been found from the June 30, 1908 explosion that occurred over the Tunguska region. The explosion flattened trees in a 2,000 square kilometer area. Luckily, that region was largely uninhabited, but reportedly one person was killed and there were very few people that reported the explosion. Forensic-like research has determined the blast was 1,000 times more powerful than a nuclear bomb explosion, and it registered 5 on the Richter scale.

The mysterious bias of life on Earth toward molecules that skew one way and not the other could be due to how light shines in star- and planet-forming clouds, researchers say.

If correct, these findings suggest the molecules of life on Earth may initially have come from elsewhere in the cosmos, scientists added.

The organic molecules that form the basis of life on Earth are often chiral, meaning they come in two forms that are mirror images, much as right and left hands appear identical but are reversed versions of each other.

Strangely, the amino acids that make up proteins on Earth are virtually all "left-handed," even though it should be as easy to make the right-handed kind. Solving the mystery of why life came to prefer one kind of handedness over the other could shed light on the origins of life, scientists say.

When it comes to antimatter, what goes up doesn't necessarily come down. In a new study, physicists weighed antimatter in an effort to determine how this strange cousin of matter interacts with gravity.

Ordinary matter atoms fall down due to the pull of gravity, but the same might not be true of antimatter, which has the same mass as matter, but opposite charge and spin. Scientists wondered whether antimatter atoms would instead fall up when pulled by gravity, and whether such a thing as antigravity exists.

"In the unlikely event that antimatter falls upward, we'd have to fundamentally revise our view of physics and rethink how the universe works," Joel Fajans, a physicist at the Lawrence Berkeley National Laboratory in California, said in a statement.

Fajans and his colleagues at the Alpha experiment at Switzerland's CERN physics lab made the first experimental measurements of the gravitational mass of antihydrogen - the antimatter equivalent of hydrogen, made of an antiproton and a positron (the antimatter counterpart to an electron).

Conducting experiments on antimatter atoms is difficult, because when matter and antimatter meet, the two annihilate. Thus, any experimental apparatus that came into contact with the material being studied would be instantly destroyed. Scientists get around this predicament by building traps for antimatter made with magnets, which force antimatter particles to stay in a certain area. As soon as the magnets are turned off, the antimatter falls onto the walls of the trap and eviscerates.

But which direction does it fall toward?