Only cat burglars can match the stealth of dark energy, credited with speeding up the universe's expansion over time, but now its fingerprints have been glimpsed in the universe's oldest radiation.
The strongest evidence for dark energy comes from supernovae, which suggest the universe is expanding faster now than in the past. But the force should also change the extent to which the cosmic microwave background (CMB), relic radiation from the big bang, is warped, or "lensed", by the gravity from distant galaxies and dark matter.
That's because the accelerating expansion of the universe should prevent the growth of very massive structures. "In a universe with no dark energy, massive objects would just keep growing, which results in more gravitational lensing," says Sudeep Das of the University of California, Berkeley.
Gravitational lensing is tough to pick out in the ancient radiation because the CMB contains random fluctuations. But Das and his colleagues have used a new type of mathematical analysis to reveal for the first time the distinctive distortions from gravitational lensing in the CMB.
Planck pending
The measurement, while not breaking any records for accuracy, bolsters the case for dark energy. "Because of dark energy's importance to both the future evolution of the universe and the foundation of physics, it is extremely important to find a variety of evidence that confirms its existence," says Stephen Boughn of Haverford College in Pennsylvania, who was not involved in the work.
Das's observations of the CMB were made with the Atacama Cosmology Telescope in Chile, but Europe's Planck satellite will soon return even more detailed measurements.
Applying the same mathematical technique to this Planck data could help astronomers better understand other important problems in cosmology. One outstanding question regards the mass of the neutrino, an elusive particle with a mass so small that it has yet to register in any measurement.
Smooth operator
Nevertheless, neutrinos ought to interact with the universe's mass on the largest scales: as these particles careen through the universe at near light-speed, they interact with ordinary matter and tend to smooth out variations in density. If the neutrinos are more massive, this effect is stronger, but restricted to shorter distances. By contrast, near-massless neutrinos aren't so forceful, but would show their effects over longer distances.
Since gravitational lensing of the CMB gives a measure of matter's tendency to clump together over a large range of distances, it can hint at the strength and scale of the smoothing. And this, in turn, will allow cosmologists to put a limit on the maximum possible mass of the neutrino.
Read more at New Scientist
Jul 16, 2011
Studies of studies show that we get things wrong
Like many claims, this is something where it's possible to gather data.
Firstly, there are individual anecdotes that demonstrate the routine humdrum of medical fact being overturned.
We used to think that hormone-replacement therapy reduced the risk of heart attacks by around half, for example, because this was the finding of a small trial, and a large observational study. That research had limitations. The small trial looked only at "surrogate outcomes", blood markers that are associated with heart attack, rather than real-world attacks; the observational study was hampered by the fact that women who got prescriptions for HRT from their doctors were healthier to start with. But at the time, this research represented our best guess, and that's often all you have to work with.
When a large randomised trial looking at the real-world outcome of heart attacks was conducted, it turned out that HRT increased the risk by 29%. These findings weren't suppressed: they were greeted eagerly, and with some horror.
Even the supposed stories of outright medical intransigence turn out to be pretty weak on close examination: people claim that doctors were slow to embrace Helicobacter pylori as the cause of gastric ulcers, when in reality, it only took a decade from the first murmur of a research finding to international guidelines recommending antibiotic treatment for all patients with ulcers.
But individual stories aren't enough. This week Vinay Prasad and colleagues published a fascinating piece of research about research. They took all 212 academic papers published in the New England Journal of Medicine during 2009. Of those, 124 made some kind of claim about whether a treatment worked or not, so then they set about measuring how those findings fitted into what was already known. Two reviewers assessed whether the results were positive or negative in each study, and then, separately, whether these new findings overturned previous research.
Seventy-three of the studies looked at new treatments, so there was nothing to overturn. But the remaining 51 were very interesting because they were, essentially, evenly split: 16 upheld a current practice as beneficial, 19 were inconclusive, and crucially, 16 found that a practice believed to be effective was, in fact, ineffective, or vice versa.
Is this unexpected? Not at all. If you like, you can look at the same problem from the opposite end of the telescope. In 2005, John Ioannidis gathered together all the major clinical research papers published in three prominent medical journals between 1990 and 2003: specifically, he took the "citation classics", the 49 studies that were cited more than 1,000 times by subsequent academic papers.
Then he checked to see whether their findings had stood the test of time, by conducting a systematic search in the literature, to make sure he was consistent in finding subsequent data. From his 49 citation classics, 45 found that an intervention was effective, but in the time that had passed, only half of these findings had been positively replicated. Seven studies, 16%, were flatly contradicted by subsequent research, and for a further seven studies, follow-up research had found that the benefits originally identified were present, but more modest than first thought.
Read more at The Guardian
Jul 15, 2011
New Virus Jumps From Monkeys to Lab Worker
It started with a single monkey coming down with pneumonia at the California National Primate Research Center in Davis. Within weeks, 19 monkeys were dead and three humans were sick. Now, a new report confirms that the Davis outbreak was the first known case of an adenovirus jumping from monkeys to humans. The upside: the virus may one day be harnessed as a tool for gene therapy.
Adenoviruses are relatively large DNA viruses—as opposed to many other viruses that replicate using RNA—that commonly cause colds and respiratory infections in humans. They’re also responsible for a variety of illnesses in cattle, dogs, horses, pigs, and other animals, but scientists thought the viruses and their ailments couldn’t jump between species.
Full article at ScienceMag
Adenoviruses are relatively large DNA viruses—as opposed to many other viruses that replicate using RNA—that commonly cause colds and respiratory infections in humans. They’re also responsible for a variety of illnesses in cattle, dogs, horses, pigs, and other animals, but scientists thought the viruses and their ailments couldn’t jump between species.
Full article at ScienceMag
Alpha-Baboon Benefits Come at Stressful Cost
But life at the top of a baboon troop isn’t all fun and games, since the alpha male must constantly struggle to maintain his social position. A new study in Science shows that alpha males suffer from much more stress than the second highest-ranking baboon, and tend to exhibit the same amount of stress hormones as baboons much lower in the hierarchy.
To study stress in a group of wild savannah baboons, the researchers collected 4,000 fecal samples from 125 adult male baboons over nine years in Amboseli, Kenya. Their goals were twofold: to determine how stress differed between high- and low-ranking baboons, and to assess whether this pattern changed in times of upheaval. The scientists tested each fecal sample for a group of hormones called glucocorticoids, which can indicate how much stress each baboon was dealing with at the time.
The researchers found that, with one notable exception, glucocorticoid levels decreased as rank increased; in other words, low rankers experienced much more stress than higher-rankers. The exception, however, was the alpha male’s stress levels, which were just as high as those of the low-ranking baboons. While the males that ranked second through eighth seemed to enjoy relatively low-stress lives, the alpha male experienced just as much stress as the baboons ranking ninth through fourteenth.
One of the most unexpected finding of this research is that the alpha males’ glucocorticoid levels were so different from the second-ranking males’. Two of the study’s other findings may account for the immense amount of stress that the highest-rankers experienced: they had a 17 percent higher rate of aggressive encounters with other baboons and they spent 29 percent more time mating than lower-rankers did. These physiological costs of maintaining the top spot are likely responsible for the sky-high stress levels exhibited by alpha males.
The stress patterns were consistent, no matter which individual held each rank; the study ran long enough for baboons to spend time at several different social ranks, and stress levels were a product of rank, rather than of consistent individual hormone profiles. In times of instability within the troop, this pattern didn’t change, but all the baboons’ stress levels went up a bit.
While short-term bursts of glucocorticoids are beneficial and can help individuals cope in stressful situations, lengthy exposure can be harmful. Over the long term, high glucocorticoid levels are known to suppress the immune system. In the study, alpha males exhibited much higher parasite loads than the baboons just beneath them in the hierarchy.
Read more at Wired Science
Caligula Statue Unveiled in Italy
The statue lay buried for nearly 2,000 years near Lake Nemi, south of Rome, where Rome’s third emperor Caligula, who ruled from 37 to 41 A.D., had two enormous “love boats.”
The statue was recovered last January, when finance police stopped tomb robbers trying to smuggle large, elaborately carved, marble pieces out of the country.
In order to find the statue's missing pieces, the archaeologists excavated the area where the tomb robbers conducted their illegal dig.
The remains of a large, semicircular nymphaeum, or fountain court, emerged. Originally enclosed by a series of 23-foot-tall columns, the fountain court boasted a niche at its center in which Caligula’ statue once stood.
Indeed, the area contained more than one hundred fragments belonging to the statue, including the head.
Moreover, the archaeologists unearthed some other 150 objects, such as vases and pieces of jewelry.
"We even found a lead pipe with a stamp bearing the name of Caius Iulius Silanus, who most likely was the villa’s first owner," said Giuseppina Ghini, of the Archaeological Superintendency of Lazio.
Made from Greek marble of Paros, considered in antiquity the world’s best and most precious, the statue shows a young robed man, sitting under a pillow on a beautifully decorated throne as the god Zeus.
On the left foot, the statue is wearing the "caligae" military boot after which the notorious Roman emperor, whose real name was Gaius Julius Caesar Augustus Germanicus, was nicknamed.
"It’s a unique sculpture, a piece of incredible beauty. Indeed, it shows a rare image of Caligula," Ghini said.
The capricious emperor, who is said to have made his favorite horse Incitatus a senator, used to sail his spectacular ships on Lake Nemi, not far from where his statue stood, indulging his sensual proclivities.
According to the Roman historian Suetonius, the vessels had "sterns studded with gems and ample space for baths, porticoes, and dining rooms, and a great variety of vines and fruit-bearing trees. Reclining on these ships all day long, he would sail amid choral dancing and singing."
Read more at Discovery News
Asteroid Vesta Comes into Focus
At a distance of only 26,000 miles (41,000 kilometers) and a few hours from orbital insertion, Dawn has snapped this incredible view of Vesta. Craters, valleys and smooth undulating features are now obvious.
Dawn is scheduled to be captured by Vesta's gravitational field at approximately 10 p.m. PT on July 15 (1 a.m. ET, July 16). No orbital insertion manoeuvre is easy, but Dawn's insertion will be a little more exciting than most. As the large asteroid's mass is not precisely known (and therefore its gravity can only be approximated), NASA scientists have to make continual measurements of Vesta's gravity as the spacecraft approaches and make small trajectory corrections when needed.
At 11:30 p.m PT on July 16 (2:30 a.m. ET, July 17), Dawn will make a scheduled communications pass to let mission control know that it is "OK." At that time, NASA predicts Dawn and Vesta will be 9,900 miles (16,000 kilometers) apart.
"It has taken nearly four years to get to this point," said Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our latest tests and check-outs show that Dawn is right on target and performing normally."
As Dawn uses ion propulsion to get around space, a very graceful method is used to allow Vesta's gravity to capture the probe. Rather than rapid, impulsive chemical rocket burns to quickly slow the vehicle down, Dawn will ease up next to the asteroid and then enter orbit.
Interestingly, Vesta isn't only a "large asteroid"; it is also considered to be a "protoplanet." Protoplanets are large celestial objects that appear to be still undergoing accretion or were once planetary embryos earlier in the solar system's history. According to research by UCLA scientists, any asteroid measuring over 165 miles (265 kilometers) in diameter is considered a protoplanet. This means the main belt objects Vesta, Ceres and Pallas are also thought to be surviving protoplanets.
More at Discovery News
Jul 14, 2011
World population to hit 7 billion by October
According to current projections, and with some of the world’s poorest nations doubling their populations in the next decade, the second milestone will be in 2025 when the global population will reach eight billion.
Dr Babatunde Osotimehin, executive director of the UN Population Fund (UNFPA), said seven billion represents a challenge, an opportunity and a call to action.
On World Population Day, July 11, he launches a campaign called “7 Billion Actions”.
“It will engage people on what it means to live in a world with seven billion people and encourage action on issues that affect all of us,” he said.
The rise in population is expected to have a devastating impact on some 215 million women who want – but do not have – access to quality reproductive health and family planning services.
The world’s five most populous countries are China (1.3 billion), India (1.2 billion), the United States (310.2 million), Indonesia (242.9 million) and Brazil (201.1 million).
The date for the eight billion population milestone is projected now to be 2025.
Full story and more facts at Aljazeera.net
Lost Rainbow Toad Found After 87 Years
The spindly-legged species was last seen in 1924 and European explorers in Borneo only made monochrome illustrations of it. A decade or so later, the CI and the SSC Amphibian Specialist Group added the species to its World’s Top 10 Most Wanted Lost Frogs campaign.
Indraneil Das of Universiti Malaysia Sarawak decided to hunt down the lost frog, and his team looked in the nearby area of Western Sarawak. In the summer of 2010 they made evening searches along the 1,329 meter high ridges of the Gunung Penrissen range to look for the toad.
After months of fruitless hunting, Das decided to include higher elevations in the team’s search. Then, one night, graduate student Pui Yong Min found the small toad two meters up a tree. Later they found another.
In the end the team had found three individuals of the missing toad species — an adult female, an adult male and a juvenile, ranging in size from 51 mm to 30 mm. All three toads exhibited those gangly limbs and the brightly colored patterns on their backs.
Talking about his team’s discovery in a press release, Das says, “They remind us that nature still holds precious secrets that we are still uncovering, which is why targeted protection and conservation is so important.”
Robin Moore of Conservation International agrees, saying in the release, “it is good to know that nature can surprise us when we are close to giving up hope, especially amidst our planet’s escalating extinction crisis.”
The slender-legged critter is only the second species on the “World’s Top 10 Most Wanted Lost Frogs” list to be found. In September 2010, the Rio Pescado Stubfoot Toad was rediscovered in Ecuador after 15 years of hiding. The spotty frog is sadly clinging on to survival.
Read more at Wired Science
July 14, 1850: What a Cool Idea, Dr. Gorrie
William Cullen had demonstrated the principle of artificial refrigeration in a University of Glasgow laboratory in 1748, by allowing ethyl ether to boil into a vacuum. American Oliver Evans designed in 1805 — but never built — a refrigeration machine that used vapor instead of liquid. Jacob Perkins used Evans’ concept for an experimental volatile-liquid, closed-cycle compressor in 1834.
Nonetheless, mid-century cooling in the tropics and subtropics — and in the temperate summer — relied on natural ice blocks carved from frozen lakes and rivers in the North, kept in shaded sheds and cellars under layers of sawdust for insulation, and often delivered at great expense by specially fitted ice ships.
Gorrie was born in the tropics, on the Caribbean island of Nevis. He received his medical education in New York state before settling in the Florida cotton-shipping port of Apalachicola. There, he served at various times as mayor, justice of the peace, postmaster and bank president, besides carrying on his medical practice.
It would be another half-century before the causes of the killer diseases malaria and yellow fever were discovered, but Dr. Gorrie knew they relied on heat and moisture to propagate. He urged the draining of swamps and the enforcement of hygiene in the town’s food market.
Gorrie also sought to improve the survival rate of his feverish patients by cooling them down. He suspended pans of ice water high in their sickrooms, so the cooled, heavy air would flow downward.
But ice was expensive in the Florida summer and often completely unavailable. Gorrie wanted to make ice mechanically. He wrote:
If the air were highly compressed, it would heat up by the energy of compression. If this compressed air were run through metal pipes cooled with water, and if this air cooled to the water temperature was expanded down to atmospheric pressure again, very low temperatures could be obtained, even low enough to freeze water in pans in a refrigerator box.
Gorrie began tinkering with compressor-coolers and had a working model by the mid-1840s. The power source was irrelevant to his invention: It could be driven by wind, water, steam or the brute force of an animal.
He applied for patents in 1848 and had a prototype built in Ohio by the Cincinnati Iron Works. It was described in Scientific American the following year, but Gorrie still had to attract venture capital to fight the existing ice-block industry.
He arranged a dramatic demonstration of his machine for a social, rather than medical, occasion. It was a muggy July in Florida. Ice from the North had been exhausted. Gorrie attended an afternoon reception given by the French consul to honor Bastille Day.
The doctor first complained about drinking warm wine in hot weather, then suddenly announced, “On Bastille Day, France gave her citizens what they wanted. [Consul] Rosan gives his guests what they want, cool wines! Even if it demands a miracle!”
Then he signaled for waiters to enter with bottles of sparkling wine on trays of ice. It was a sensation: mechanically made ice in the sweltering Florida summer. Smithsonian magazine dubbed that party the “chilly reception.”
Read more at Wired
Jul 13, 2011
Rare Hermaphrodite Butterfly Hatches in London Museum
The gynandromorph Papilio Memnon butterfly fortuitously hatched in the puparium at this year’s Sensational Butterflies exhibition. It is one of just 200 gynandromorph butterflies among the 4.5 million butterfly specimens in the museum.
The term gynandromorph comes from the Greek “Gyn” to mean female, and “Andro” to mean male. The butterfly has distinctly different male and female markings — darker colorings on the male side and paler coloring, with flecks of blue, red and tortoiseshell on the female side.
As the coloring denotes, the butterfly is literally half female, half male — its sexual organs are half and half, and, as the BBC adds: “…even its antennae are different lengths”.
The Museum explains: “Insects can become gynandromorphs if the sex chromosomes do not properly separate during the first division of a fertilized egg, resulting in an insect with both male and female cells. They can also occur when an egg with two sex chromosomes, instead of a single one, gets fertilized by two sperm.”
Gynandromorph lobsters, spiders and crabs have also been observed.
Read more at Wired Science
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