check the “Self-Medication in Animals Much More Widespread Than Believed” post here

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Dead Star Warps Light of Companion Red Star, Astronomers Say

NASA’s Kepler space telescope, in concert with Cornell-led measurements of stars’ ultraviolet activity, has observed the effects of a dead star bending the light of its companion red star.

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The findings are among the first detections of this effect — a result predicted by Einstein’s theory of general relativity — in binary, or double, star systems.

The dead star, also called a white dwarf, is the burnt-out core of what used to be a star like our sun. It is locked in an orbiting dance with its partner, a small “red dwarf” star. While the tiny white dwarf is physically smaller than the red dwarf, it is more massive. When the white dwarf passed in front of its star, its gravity caused the starlight to observably bend and brighten.

“This white dwarf is about the size of Earth but the mass of the sun,” said Phil Muirhead, Ph.D. ’11, of the California Institute of Technology and lead author of the findings to be published April 20 in theAstrophysical Journal, titled “Characterizing the cool KOIs: A mutually eclipsing post-common envelope binary.”

“It’s so hefty that the red dwarf, though larger in physical size, is circling around the white dwarf,” Muirhead continued.

The research team used Cornell-led ultraviolet measurements of the star called (Kepler Object of Interest) KOI-256 taken by the Galaxy Evolution Explorer (GALEX), a NASA space telescope operated by Caltech. The GALEX observations were conducted by Cornell researchers Jamie Lloyd, associate professor of astronomy and of mechanical and aerospace engineering; Kevin Covey, former postdoctoral associate now at Lowell Observatory; and Lucianne Walkowicz of Princeton University and Evgenya Shkolnik of Lowell Observatory.

Still in early phases and for which Cornell students are now being recruited by Lloyd, the GALEX program measures ultraviolet activity in all the stars in the Kepler field of view — an indicator of potential habitability for planets.

Graduate student and co-author Jim Fuller also did a theoretical analysis of the star system in the context of its future and past evolutions.

The red dwarf orbits the white dwarf in just 1.4 days. This orbital period is so short that the stars must have previously undergone a “common-envelope” phase in which the red dwarf orbited within the outer layers of the star that formed the white dwarf, Fuller explained.

Moreover, the short orbital period means the red dwarf’s days are numbered: In a few billion years, the intense gravity of the white dwarf will strip material off the red dwarf, forming a hot accretion disk of in-falling material around the white dwarf.

“This system is especially exciting because it allows us to accurately characterize the peaceful state of these systems before the violent mass-transfer phase begins,” Fuller said.

Kepler’s primary job is to scan stars in search of orbiting planets. As the planets pass by, they block the starlight by miniscule amounts, which Kepler’s sensitive detectors can see.

So far, Kepler has identified more than 2,700 planet candidates. Still ongoing is the mission’s search for planets similar to Earth in size and temperature that orbit a star like our sun. Ultimately, Kepler will reveal how common Earth-size planets are in the Milky Way galaxy.

To learn more about this particular star system, Muirhead and colleagues also used the Hale Telescope at Palomar Observatory near San Diego. Using a technique called radial velocity, they discovered that the red dwarf was wobbling around like a spinning top. The wobble was too big to be from the tug of a planet. That’s when they knew they were looking at a massive white dwarf passing behind the red dwarf, rather than a gas giant passing in front.

One of the consequences of Einstein’s theory of general relativity is that gravity bends light. Astronomers regularly observe this phenomenon, often called gravitational lensing, which has been used to discover new planets and hunt for free-floating planets.

In this new study, scientists used gravitational lensing to determine the mass of the white dwarf. By combining this information with all the data they acquired, they were able to accurately measure the mass of the red dwarf and the physical sizes of both stars.

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last scientist descovery of : How Herpesvirus Invades Nervous System ?!

Northwestern Medicine scientists have identified a component of the herpesvirus that “hijacks” machinery inside human cells, allowing the virus to rapidly and successfully invade the nervous system upon initial exposure.

Led by Gregory Smith, associate professor in immunology and microbiology at Northwestern University Feinberg School of Medicine, researchers found that viral protein 1-2, or VP1/2, allows the herpesvirus to interact with cellular motors, known as dynein. Once the protein has overtaken this motor, the virus can speed along intercellular highways, or microtubules, to move unobstructed from the tips of nerves in skin to the nuclei of neurons within the nervous system.

This is the first time researchers have shown a viral protein directly engaging and subverting the cellular motor; most other viruses passively hitch a ride into the nervous system.

“This protein not only grabs the wheel, it steps on the gas,” says Smith. “Overtaking the cellular motor to invade the nervous system is a complicated accomplishment that most viruses are incapable of achieving. Yet the herpesvirus uses one protein, no others required, to transport its genetic information over long distances without stopping.”

Herpesvirus is widespread in humans and affects more than 90 percent of adults in the United States. It is associated with several types of recurring diseases, including cold sores, genital herpes, chicken pox, and shingles. The virus can live dormant in humans for a lifetime, and most infected people do not know they are disease carriers. The virus can occasionally turn deadly, resulting in encephalitis in some.

Until now, scientists knew that herpesviruses travel quickly to reach neurons located deep inside the body, but the mechanism by which they advance remained a mystery.

Smith’s team conducted a variety of experiments with VP1/2 to demonstrate its important role in transporting the virus, including artificial activation and genetic mutation of the protein. The team studied the herpesvirus in animals, and also in human and animal cells in culture under high-resolution microscopy. In one experiment, scientists mutated the virus with a slower form of the protein dyed red, and raced it against a healthy virus dyed green. They observed that the healthy virus outran the mutated version down nerves to the neuron body to insert DNA and establish infection.

“Remarkably, this viral protein can be artificially activated, and in these conditions it zips around within cells in the absence of any virus. It is striking to watch,” Smith says.

He says that understanding how the viruses move within people, especially from the skin to the nervous system, can help better prevent the virus from spreading.

Additionally, Smith says, “By learning how the virus infects our nervous system, we can mimic this process to treat unrelated neurologic diseases. Even now, laboratories are working on how to use herpesviruses to deliver genes into the nervous system and kill cancer cells.”

Smith’s team will next work to better understand how the protein functions. He notes that many researchers use viruses to learn how neurons are connected to the brain.

“Some of our mutants will advance brain mapping studies by resolving these connections more clearly than was previously possible,” he says.

Nature Versus Nurture: Better Looking Birds Have Healthier Babies, Finds Study of Great Tits

A female great tits’ (Parus major) appearance is shown to signal healthy attributes in offspring in a paper in BioMed Central’s open access journal Frontiers in Zoology. The black stripe across her breast and white patches on her cheeks correlate to a chick’s weight at two weeks and immune strength respectively — though the former seems to signal a genetic benefit and the latter can affect an ‘adopted’ chick’s health, suggesting nurture is involved.
Taking two mothers with different patterning, and swapping their chicks, researchers from Palacky University in the Czech Republic were able to investigate the growth and health of the infants and the ‘ornamentation’ of their mothers. They compared the offspring’s weight, size and immune strength and found a correlation between the chick’s weight at two weeks and the size of black breast stripe on the genetic mother.

The immaculateness of both genetic and foster mother’s white cheek patch was related to the strength of chick’s immune response suggesting that this was due to both nurture and genetics. In contrast the body size of a chick was related only to the body size of its genetic mother and not to ornamentation at all.
In these socially monogamous birds both the males and females are brightly coloured, however neither the cheek patch nor the stripe in males affected the health of the babies.
Talking about how the ornaments can have evolved to signal reproductive fitness, Vladimír Remeš and Beata Matysioková who performed this study explained, “Bigger healthier babies are important to the reproductive success of individuals, because they are more likely to survive to adulthood — so it is useful for birds to be able to work out which potential mates will produce the best babies. Maintaining bright colouration uses up resources which could otherwise be invested in reproduction or self-maintenance — consequently the evolution and maintenance of ornamentation in female great tits is probably due to direct selection by males.