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Searching for signals from extraterrestrials can be a ticklish business. Astronomer John Learned thinks tickling certain stars in just the right way might be a good strategy for ET to phone Earth.

Those stars, known as Cepheid variables, brighten and dim on a regular schedule. In 1908, after analyzing stars on photographic plates at Harvard College Observatory, Henrietta Swan Leavitt reported that a Cepheid’s maximum brightness depends on the timing of its bright-dim cycle. The longer the period, the brighter the star. Other astronomers soon realized that they could use the period-brightness relationship to measure distances to remote galaxies.

A century later, Learned and colleagues are proposing a new use for Cepheids. In an article recently posted online (arxiv.org/abs/0809.0339), the researchers suggest that tinkering with the core of a Cepheid variable using a beam of neutrinos could be an effective way for advanced civilizations to communicate. This modulation, or “tickling,” would alter the phase at which the star brightens and slightly shorten the time it takes for the star to wax and wane, creating a new pattern that distant observers might detect.

Although most SETI (search for extraterrestrial intelligence) programs use radio telescopes to look for alien broadcasts, fiddling with Cepheids has advantages for both senders and receivers, Learned and his colleagues note. Not only can the stars be seen from afar, but “Cepheids are great because any emergent civilization will surely find them and monitor them for the very same reasons we do,” says Learned, of the University of Hawaii at Manoa. And astronomers have searchable records of Cepheids that go back well over a century.

Another advantage, says Learned, is that a Cepheid star — unlike a directed radio signal — would radiate in all directions, making it more likely that the radiation would be recorded on Earth.

“If it could work, then this is an answer to one way to build an omnidirectional beacon,” says Jill Tarter, director of the Center for SETI Research in Mountain View, Calif. “It would be an example of an ‘almost natural’ signal that would get captured in a survey of the universe by an emerging technology, that’s us, and finally recognized in a database by some curious grad student.”

Neutrinos seem ideal for tinkering with Cepheids because these subatomic particles travel rapidly and interact with matter so weakly that they could penetrate all the way to the star’s core. If delivered at just the right time during the Cepheid’s cycle, when it’s in its compact, dim phase, the energetic neutrinos “would change both the pulsation rate and the peak amplitude” of the star using a minimum of energy, Learned says. “We leave it as an engineering problem for the star-tickling civilization out there,” to determine the optimal energy, the researchers wrote.

Detecting the pattern won’t be easy. “One glitch tells us nothing,” Learned says. “It will take discerning a pattern of glitches, and some regularity to find something interesting.”

Although star tickling is beyond current human ability, “it’s silly to try to guess whether it’s feasible for some unknown, incredibly advanced civilization to be able to do this,” comments Jeff Scargle of NASA’s Ames Research Center in Moffett Field, Calif. “It’s a really smart idea because … the star generates the energy; all you have to do is change it a little bit. It’s a nice way to piggyback on what nature has supplied.”

He points out that researchers could start looking for artificially modulated signals by combing through the huge database on Cepheids amassed over decades by amateur and professional astronomers.

Neutrinos play a more direct role in another new way to look for ET. In a paper posted online in March, Zurab Silagadze of the Budker Institute of Nuclear Physics in Novosibirsk, Russia, details how neutrinos created by alien civilizations might be detected on Earth (arxiv.org/abs/0803.0409). The article is a follow-up to an idea that researchers first speculated about nearly three decades ago, Silagadze says.

Particle accelerators that collide beams of muons — heavy cousins of the electron — would produce intense neutrino beams. (Such accelerators are possible with known technology.) An advanced civilization with such a collider could communicate with other societies via neutrinos. The simplest possibility, Silagadze says, is to “periodically switch on and off the neutrino source to organize short and long signals, a kind of Morse code.”

“Neutrino communication schemes are broad band, and you do not have to know the transmission frequency,” he adds, allowing signals to be sent to the maximum number of unknown civilizations.

Suppose, Silagadze says, that a civilization within 20 light-years of the solar system produces 100-trillion-electronvolt beams of neutrinos directed toward Earth. He calculates that a neutrino detector called IceCube, now under construction beneath ice at the South Pole, could detect seven to 10 muons per year generated by neutrino impacts in the ice.

IceCube researcher Buford Price of the University of California, Berkeley, says that those muons, unlike random muons from space, “would all point closely in the direction of the muon collider that belongs to the advanced civilization।” The signal would be easier to discern if the senders turned it on and off. http://louis-j-sheehan.net

About half finished, IceCube is now taking data. Says Price: “We will let the world know if we see a beam correlated in both direction and time.”

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Cancer is not just a terrible disease but a strange one. Tumor cells must switch on certain genes in order to thrive and multiply. You might expect that natural selection would have eliminated those genes, because they kill off their owners. Far from it. A number of cancer genes, known as oncogenes, have actually been favored by natural selection over the past few million years। Oncogenes, in other words, have boosted the reproductive success of their owners, and have even been fine-tuned by evolution. http://Louis2J2Sheehan2Esquire.US

Humans are not alone in getting cancer. In fact, it seems to be a pretty inescapable risk of being an animal. As cells divide and mutate, some mutations may make cells ignore the needs of the body and multiply madly. That’s too bad for other animals, but there’s a silver lining for us: by studying other animals, scientists can get some clues to how cancer evolves in us.

The delicate swordtail (Xiphophora cortezi) is particularly prone to getting melanomas (the bottom picture here shows a fish with a tumor in its tail). When Andre Fernandez and Molly Morris of Ohio University went fishing for delicate swordtails in mountain streams in Mexico, they found six fish with melanomas in a single day’s catch. These melanomas are particularly nasty–instead of striking old fish that are going to die soon anyway, they turn up in young breeders and kill them over a few months.

Melanomas develop from pigment-producing cells in the skin. As these tumors develop, the cells inside them produce lots of extra proteins from a gene called Xmrk. Despite Xmrk’s harm, it has survived in good working order for a long time. Functioning versions of Xmrk exist not just in delicate swordtails, but in related swordtail speices that descend from a common ancestor that lived a few million years ago.

How does such a dangerous gene continue to survive for so long? Fernandez and Morris have just published an experiment that might solve the mystery. A lot of delicate swordtails have large dark spots on their tails, like the one shown on the top fish here. Xmrk is essential for producing those spots. Other fish have been shown to use stripes, spots, and other visual patterns to attract mates. So Fernandez and Morris wondered what the female delicate swordtails thought of the Xmrk spots on males.

Turns out, they like them a lot. When offered a chance to pay a visit to one of two male fish, female delicate swordtails from two populations in Mexico spent more time with spotted males than spotless ones. And they also preferred to consort with males with big spots over males with little ones.

The Xmrk gene definitely imposes an evolutionary cost on fish. But that cost may be erased by the benefit it gives male fish through sexual selection. By the time a male delicate swordtail dies from an Xmrk tumor, he may have mated with a number of females, which will pass down the gene to their young.

We humans may also be shaped by the trade-off between sexual selection and the cost of cancer। Testosterone and related hormones latch onto androgen receptors on the surface of some cells. It’s important for the development of men’s bodies, for example, and the growth of body hair. It also plays a role in the production of sperm. These kinds of traits can affect the success men have in finding mates and having children. But the androgen receptor gene also becomes active during prostate cancer. In fact, versions of the gene that increase sperm count in men also raise the risk of cancer. http://Louis2J2Sheehan2Esquire.US

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Although most people with psychiatric disorders don't attack others or pursue lives of

crime, the relationship of mental illness to violence remains unclear. A long-term study in New

Zealand now links elevated violence rates in young adults to the presence of at least one of

three psychiatric ailments—alcohol dependence, marijuana dependence, and a range of psychotic

experiences and beliefs called schizophrenia-spectrum disorder.

"Our study suggests that a significant proportion of the violence that frightens and injures

the general public may be attributed to young adults who are prone to [these disorders], many

of whom have not been hospitalized or treated," says a team led by Louise Arseneault and

Terrie E. Moffitt of the Institute of Psychiatry in London. No other psychiatric disorders

showed this link in the recent study.

Earlier delinquency and drug problems appear to have contributed both to the three disorders

and to violence in young adults, the scientists say in the October Archives of General Psychiatry.

The researchers studied 961 men and women, all age 21, who were born in New Zealand

and have been interviewed at regular intervals since age 5. Self-reports and official conviction

records identified acts of physical violence—such as an attack on someone with a weapon, robbery,

rape, and gang fighting—committed by each participant in the year before the most

recent interview.

While people with alcohol dependence, marijuana dependence, schizophrenia-spectrum disorder,

or more than one of these diagnoses constituted one-fifth of the sample, they were

responsible for more than half of all self-reported and recorded violent crimes, the researchers

report.

People with schizophrenia-spectrum disorder displayed an increased risk of violence that

was independent of the effects of substance abuse. The data indicate that a tendency to perceive

excessive threat in their surroundings contributed to their violent acts, Arseneault and

her coworkers report.

The New Zealand study is the most comprehensive communitywide probe of mental disorders

and violence, says psychologist John T. Monahan of the University of Virginia in

Charlottesville.

However, violent behavior occurs more often in the United States than in New Zealand,

Monahan notes. "More of the violence in New Zealand may be attributable to mental illness

than in a place like New York City," he says.

Other studies, which focus on people discharged from U.S. psychiatric hospitals, find no

increased violence among those with schizophrenia or with violent delusions or fantasies.

Certain personality disturbances may instead promote violence, says psychologist Jeffrey

G. Johnson of Columbia University. Traits such as suspiciousness of others and lack of empathy

markedly contributed to violence in young adults in the general population who were

tracked for 8 years in upstate New York, Johnson and his coworkers report in the September

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