Bad Weather Threatens Shuttle Launch

CAPE CANAVERAL, Fla. (AP) - NASA pressed ahead with Thursday's planned launch of shuttle Atlantis, even though bad weather threatened to delay the mission to add another science lab to the international space station.

Forecasters said there was a 70 percent chance that rain, clouds and possibly even a severe thunderstorm would keep Atlantis on the pad for yet another day. The space shuttle already is two months late in delivering the European lab, Columbus, to the space station.

Faulty fuel gauges grounded Atlantis in December. Engineers worked round the clock and through the holidays to fix the problem, which turned out to be a bad connector in the external fuel tank.

Although confident of the repair, NASA officials acknowledged they would be monitoring Atlantis' fuel gauges with more interest than usual, once fueling got under way.

NASA said at least three of the four fuel gauges must work properly once Atlantis' tank is filled in order for the launch to proceed. The gauges are part of a critical safety system to help ensure that the main engines do not run on an unexpectedly empty tank during the 8 1/2-minute climb to orbit. They have performed erratically during countdowns for nearly three years and postponed several launches.

Columbus—a $2 billion high-tech laboratory—is the European Space Agency's primary contribution to the space station. In the making for 23 years, the lab has endured station redesigns and slowdowns, as well as a number of shuttle postponements and two shuttle accidents.

It will join the U.S. lab, Destiny, already flying for seven years. The much bigger Japanese lab Kibo, or Hope, will require three shuttle flights to get off the ground, beginning in March.

The Europeans also are on the verge of launching their new cargo ship, Jules Verne. It's scheduled to blast off from French Guiana in early March.

"There's going to be a lot of pride, a lot of people with good feelings in their stomachs, when these things go up," said Europe's space station program manager, Alan Thirkettle.

The European Space Agency already has spent more than $7 billion on the station program and plans to invest an additional $6 billion by Thirkettle said.

Besides Columbus, Atlantis will drop off a new space station resident, a French Air Force general who will take the place of NASA astronaut Daniel Tani and get Columbus working. Tani will return to Earth aboard the shuttle, ending a mission of nearly four months.

NASA is anxious about getting Atlantis flying as soon as possible to keep alive its plan for six shuttle missions this year. The space agency faces a 2010 deadline for finishing the station and retiring the shuttles.

DNA Is Blueprint, Contractor And Construction Worker For New Structures

DNA is the blueprint of all life, giving instruction and function to organisms ranging from simple one-celled bacteria to complex human beings. Now Northwestern University researchers report they have used DNA as the blueprint, contractor and construction worker to build a three-dimensional structure out of gold, a lifeless material.

Using just one kind of nanoparticle (gold) the researchers built two common but very different crystalline structures by merely changing one thing -- the strands of synthesized DNA attached to the tiny gold spheres. A different DNA sequence in the strand resulted in the formation of a different crystal.

The technique, to be published in the journal Nature, and reflecting more than a decade of work, is a major and fundamental step toward building functional "designer" materials using programmable self-assembly. This "bottom-up" approach will allow scientists to take inorganic materials and build structures with specific properties for a given application, such as therapeutics, biodiagnostics, optics, electronics or catalysis.

Most gems, such as diamonds, rubies and sapphires, are crystalline inorganic materials. Within each crystal structure, the atoms have precise locations, which give each material its unique properties. Diamond's renowned hardness and refractive properties are due to its structure -- the precise location of its carbon atoms.

In the Northwestern study, gold nanoparticles take the place of atoms. The novel part of the work is that the researchers use DNA to drive the assembly of the crystal. Changing the DNA strand's sequence of As, Ts, Gs and Cs changes the blueprint, and thus the shape, of the crystalline structure. The two crystals reported in Nature, both made of gold, have different properties because the particles are arranged differently.

"We are now closer to the dream of learning, as nanoscientists, how to break everything down into fundamental building blocks, which for us are nanoparticles, and reassembling them into whatever structure we want that gives us the properties needed for certain applications," said Chad A. Mirkin, one of the paper's senior authors and George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences, professor of medicine and professor of materials science and engineering. In addition to Mirkin, George C. Schatz, Morrison Professor of Chemistry, directed the work.

By changing the type of DNA on the surface of the particles, the Northwestern team can get the particles to arrange differently in space. The structures that finally form are the ones that maximize DNA hybridization. DNA is the stabilizing force, the glue that holds the structure together. "These structures are a new form of matter," said Mirkin, "that would be difficult, if not impossible, to make any other way."

He likens the process to building a house. Starting with basic materials such as bricks, wood, siding, stone and shingles, a construction team can build many different types of houses out of the same building blocks. In the Northwestern work, the DNA controls where the building blocks (the gold nanoparticles) are positioned in the final crystal structure, arranging the particles in a functional way. The DNA does all the heavy lifting so the researchers don't have to.

Mirkin, Schatz and their team just used one building block, gold spheres, but as the method is further developed, a multitude of building blocks of different sizes can be used -- with different composition (gold, silver and fluorescent particles, for example) and different shapes (spheres, rods, cubes and triangles). Controlling the distance between the nanoparticles is also key to the structure's function.

"Once you get good at this you can build anything you want," said Mirkin, director of Northwestern's International Institute for Nanotechnology.

"The rules that govern self-assembly are not known, however," said Schatz, "and determining how to combine nanoparticles into interesting structures is one of the big challenges of the field."

The Northwestern researchers started with gold nanoparticles (15 nanometers in diameter) and attached double-stranded DNA to each particle with one of the strands significantly longer than the other. The single-stranded portion of this DNA serves as the "linker DNA," which seeks out a complementary single strand of DNA attached to another gold nanoparticle. The binding of the two single strands of linker DNA to each other completes the double helix, tightly binding the particles to each other.

Each gold nanoparticle has multiple strands of DNA attached to its surface so the nanoparticle is binding in many directions, resulting in a three-dimensional structure -- a crystal. One sequence of linker DNA, programmed by the researchers, results in one type of crystal structure while a different sequence of linker DNA results in a different structure.

"We even found a case where the same linker could give different structures, depending on the temperatures at which the particles were mixed," said Schatz.

Using the extremely brilliant X-rays produced by the Advanced Photon Source synchrotron at Argonne National Laboratory in combination with computational simulations, the research team imaged the crystals to determine the exact location of the particles throughout the structure. The final crystals have approximately 1 million nanoparticles.

"It took scientists decades of work to learn how to synthesize DNA," said Mirkin. "Now we've learned how to use the synthesized form outside the body to arrange lifeless matter into things that are useful, which is really quite spectacular."

The Nature paper, entitled "DNA-programmable nanoparticle crystallization" is to be published January 31, 2008. In addition to Mirkin and Schatz, other authors are Sung Yong Park, a former postdoctoral fellow in Schatz's lab and now at the University of Rochester (lead author); graduate student Abigail K. R. Lytton-Jean, Northwestern University; Byeongdu Lee, Advanced Photon Source, Argonne National Laboratory; and Steven Weigand, Northwestern's DND-CAT Synchrotron Research Center at Argonne's Advanced Photon Source.

New Decontamination System Kills Anthrax Rapidly Without Lingering Effects

In October 2001, letters containing anthrax spores were mailed to several news media offices and two U.S. senators, killing five people and infecting 17 others. Clearing the Senate office building of the spores with chlorine dioxide gas cost $27 million, according to the Government Accountability Office. Cleaning the Brentwood postal facility outside Washington cost $130 million and took 26 months.

Researchers at the Georgia Tech Research Institute (GTRI) in collaboration with Austin-based Stellar Micro Devices, Inc. (SMD) have developed prototypes of a rapid, non-disruptive and less expensive method that could be used to decontaminate bioterrorism hazards in the future.

Using flat panel modules that produce X-rays and ultraviolet-C (UV-C) light simultaneously, the researchers can kill anthrax spores in two to three hours without any lingering effects. The system also has the ability to kill anthrax spores hidden in places like computer keyboards without causing damage.

"This is certainly an improvement over previous techniques," said Brent Wagner, GTRI principal research scientist and director of its Phosphor Technology Center of Excellence (PTCOE). "The UV-C attacks spores on surfaces and the X-rays penetrate through materials and kill spores in cracks and crevices."

X-ray irradiation is used commercially to sterilize medical products and food by disrupting the ability of a microorganism to reproduce. UV-C also prevents replication, but both types of radiation can penetrate the outer structure of an anthrax spore to destroy the bacteria inside.

The current decontamination standard -- chlorine dioxide gas -- kills microorganisms by disrupting transport of nutrients across the cell wall, but cannot reach hidden spores. Hard surfaces must be cleaned independently with harsh liquid chlorine dioxide. In addition, people cannot re-enter a room fumigated with chlorine dioxide until the gas is neutralized with sodium bisulfite vapor and vented from the building.

The new decontamination system resembles a coat rack with radiation modules arranged on rings at various heights that face outward to broadcast radiation throughout a room. Since the X-rays and UV-C are lethal at the flux densities used, the system operates unattended and is turned on outside the affected space.

UV-C light in the modules is produced using the optical and electrical phenomenon of cathodoluminescence. Numerous electron beams are generated by arrays of cold cathodes, each acting like the electron gun in a cathode ray tube.

"When an electron beam hits a powder phosphor, it luminesces and emits visible and/or non-visible light," explained Hisham Menkara, a senior research scientist in GTRI's Electro-Optical Systems Laboratory.

GTRI became involved in SMD's project, which was funded by the Air Force Research Laboratory's Small Business Innovation Research program, because the PTCOE housed UV-C phosphors created and patented by Sarnoff Corporation in the mid-1970s.

"We knew that Georgia Tech had experts in powder phosphors with regard to flat panel displays and we approached them to develop new phosphors for our decontamination purpose," said Mark Eaton, president and CEO of SMD. "We were fortunate that they had UV-C phosphors available from decades earlier."

With the Sarnoff phosphors in hand, Wagner and Menkara set off to determine the best UV-C emitting phosphor and optimize its properties for use with X-rays in SMD's small flat panel display.

To find the best phosphor that emitted light in the UV-C region of the spectrum -- wavelengths below 280 nanometers -- the emission spectra of each phosphor was measured against the DNA absorption curve. This curve shows the optimal wavelengths to destroy an organism's DNA.

After investigating many different phosphors, the researchers chose lanthanum phosphate:praseodymium (LaPO4:Pr or LAP:Pr) as the most efficient phosphor, with a power efficiency near 10 percent. Since the UV emission didn't fall completely under the DNA absorption curve, the relative "killing efficiency" was approximately 50 percent.

In the laboratory, Menkara created the phosphor by mixing precursors lanthanum oxide, hydrogen phosphate and praseodymium fluoride (La2O3, H3PO4 and PrF3, respectively) in a glass beaker with methanol (CH3OH) and ammonium chloride (NH4Cl). Air drying the mixture in a fume hood caused the methanol to completely evaporate.

The resultant cake was crushed into a fine powder, heated in a furnace to a temperature as high as 1250 degrees Celsius for two hours and crushed again.

"To determine the best conditions for producing the highest efficiency phosphor, we tried different precursors and completed the firing under different atmospheric conditions and temperatures," explained Menkara.

Test results showed that higher temperatures were more efficient and a capped quartz tube was the best container to hold the powder inside the furnace. Wagner and Menkara also found that adding lithium fluoride (LiF) and reducing the praseodymium concentration increased the cathodoluminescent properties of the LAP:Pr phosphor.

With the improved phosphor, laboratory tests conducted by SMD showed that the combined X-ray and UV-C decontamination system could kill anthrax spores.

GTRI researchers hope to develop new UV-C phosphors that can achieve cathodoluminescent efficiency higher than 10 percent with an emission spectrum that provides increased coverage of the DNA absorption curve.

With increased efficiency, UV-C panels could be used for sterilizing medical equipment or purification applications.

"We may be able to use UV-C panels to clean wastewater, which would be better than the lamps currently used. In the environment where the lamps must operate, they are very difficult to clean, whereas flat panels could be cleaned with a squeegee," noted Eaton.

Another potential application is to kill viruses in buildings used to house chickens. Current methods involve removing the chickens and raising the temperature in the chicken houses for several days to deactivate the virus.

"With the combined UV-C/X-ray system, you could turn the system on for a few hours, kill the viruses and as soon as you turn it off, the chickens could come right back in," said Wagner.

Tiny gene differences make us who we are

Scientists have found more than 500 genes that account for variations across human populations including skin colour, height and vulnerability to disease, according to a new study.

By comparing millions of fragments of genetic code from individuals in four groups - from Nigeria, China, Japan and northwest Europe - researchers say that natural selection has played a key role in these differences.

The findings, which are published online ahead of print in the journal Nature Genetics, hold particular promise for understanding the genetic underpinning of certain diseases.

The researchers, led by Dr Lluis Quintana-Murci of France's National Centre for Scientific Research pinpoints, for example, the tiny genetic variation in the CR1 gene that has made 85% of Africans highly resistant to malaria.

Most other populations in the world do not share this variant and are thus more susceptible to the mosquito-borne disease.

Other identified genetic variations - called single nucleotide polymorphisms or SNPs and pronounced 'snips' - could help explain why rates of diabetes, obesity and hypertension differ from one region to another.

Once the specific bit of genetic code responsible for a predisposition to a certain illness or condition has been identified, scientists can then set about trying to find a drug to treat it.

Variation matters

SNPs occur when one of the four chemical building blocks of DNA varies in a particular segment of DNA when compared with other members of the same species.

Some of these genetic mutations have happened through positive selection; they provide an advantage in the struggle to survive.

Being resistant to malaria is more useful in sub-Saharan Africa than in Norway, for example.

Others are driven by negative selection, the process by which genetic traits are forced out of a species because they impede survival.

Hair and eye colour

The study, based on the international HapMap catalogue of genetic variants within and among populations around the world, found SNPs that also account for differences in eye and hair colour.

"These genes played a role in adapting to our environment, and their mutation gave rise to certain advantages," says Quintana-Murci.

"But the genes that explain the phenotypic differences between populations only represent a tiny part of our genome, confirming once again that the concept of 'race' from a genetic standpoint has been abolished," he adds.

Genotype is the genetic blueprint contained in DNA, while phenotype is the individual organism brought into being based on the instructions contained in that DNA.

The study identified 582 genes that mutated through natural selection, probably between 10,000 and 60,000 years ago.

Online justice a world first

Some court cases will soon be heard online in Australia, with judges receiving lawyers' arguments by email, a state minister says.

The system, known as JusticeLink, is the world's first computer system that links courts across jurisdictions, says New South Wales (NSW) state attorney general John Hatzistergos.

He says the system is to be rolled out in courts across Australia's largest state over the next 12 months.

Prosecutors and defence lawyers will log on to a bulletin board and type their arguments, which would then be sent to the judge by email.

The judge would make orders in real time.

Hatzistergos says the system will streamline the legal process, "saving millions of dollars in costs and countless hours spent in the courtroom".

The cost of the scheme is put at A$48 million (US$43 million).

Nine firms have tested the system and the state Supreme Court has used it, already holding 167 hearings on civil matters online.

The system will be rolled out on 11 February in the NSW District Court, which governs courts across the state, and is expected to be in operation in every criminal and civil court in the state by next year.

The system will not be used for committal proceedings and trials, which will still be conducted in person, but for more preliminary procedural hearings, including such matters as bail applications.

Spare jawbone grown in gut

Scientists say they have replaced a 65-year-old patient's upper jaw with a bone transplant cultivated from stem cells isolated from his own fatty tissue and grown inside his abdomen.

The Finnish researchers say this opens up new ways to treat severe tissue damage and makes the prospect of custom-made living spares parts a step closer.

"There have been a couple of similar sounding procedures before, but these didn't use the patient's own stem cells that were first cultured and expanded in laboratory and differentiated into bone tissue," says Professor Riitta Suuronen of the Regea Institute of Regenerative Medicine, part of the University of Tampere.

She says the patient is recovering more quickly than he would have if he had received a bone graft from his leg.

"From the outside nobody would be able to tell he has been through such a procedure," she says.

The team used no materials from animals, preventing the risk of transmitting viruses than can be hidden in an animal's DNA, and followed European Union guidelines, she says.

Stem cells are the body's master cells and they can be found throughout the blood and tissues.

Researchers have recently found that fat contains stem cells that can be directed to form a variety of different tissues.

Using a patient's own stem cells provides a tailor-made transplant that the body should not reject.

Suuronen and her colleagues at the Helsinki University Central Hospital isolated stem cells from the patient's fat and grew them for two weeks in a specially formulated nutritious soup that included the patient's own blood serum.

In this case they identified and pulled out cells called mesenchymal stem cells, immature cells than can give rise to bone, muscle or blood vessels.

When they had enough cells to work with, they attached them to a scaffold made out of a calcium phosphate biomaterial and then put it inside the patient's abdomen to grow for nine months.

The cells turned into a variety of tissues and even produced blood vessels, the researchers say.

The block was later transplanted into the patient's head and connected to the skull bone using screws and microsurgery to connect arteries and veins to the vessels of the neck.

The patient's upper jaw had previously been removed due to a benign tumour and he was unable to eat or speak without the use of a removable prosthesis.

Suuronen says her team has submitted a report on the procedure to a medical journal.

Biggest Space Rocket Ever Made Put on Display!

Saturn V, commonly known as the Moon Rocket, was the first rocket to carry a manned mission into space for a lunar landing. On 16th July 1969, it launched the Apollo 11 mission into the Earth's orbit and put the first man on the Moon.
Now, after more than 35 years of laying outside the neighboring U.S. Space & Rocket Center, NASA is putting the colossus on display for the large public.

It stands 110 meters tall, 10 meters in diameter, weighs 3 million kilograms and, when functional, its 5 Rocketdyne F-1 engines were able to output about 34 MN of thrust, but it was not the most powerful rocket ever made. Only the Russian rocket Energia was able to provide with more thrust, regardless of the fact that it only flew in two test missions. Saturn V was designed under the direction of German rocket builder Wernher von Braun, at the Marshall Space Flight Center.

The 23.4 million U.S. dollar project was started two and a half years ago so that the renovated rocket would be ready in time for the 50th anniversary of the launch of the first U.S. artificial satellite. To house the rocket, a 6335 square meter building had to be raised by the museum hired contractor, using money received from donations, federal grants, local funding and bond money. The shear size of the rocket disabled the possibility to move it into its new home in one piece, and now lies split up in sections for display.

Although it stood in the Alabama sun and was house for families of raccoons, birds, green algae and possums for the last three decades, Larry Capps, the CEO of the Museum, says the rocket didn't requires as much work as originally estimated. New paint and replacement of fragile metal made the Saturn V rocket look like in its days of glory. On the other hand, the capsule wasn't so fortunate, and due to the bad shape, it had to be scrapped and a substitute mockup had to be found. Capsule and escape tower have been provided by the Marshall Space Flight Center from its personal 'bone yard'.

"The construction of its new home, moving and restoration of the rocket cost the museum about 9.5 million dollars, the rest of the money being spent on the new visitor center", said Larry Capps. As putting the rocket in a upright position would have restricted much of the visitors from viewing the whole structure, thus the museum decide to lay it on its side, with the first of the two stages and the upper sections suspended on thin cables.

Also, the museum has in plan to move even more of Apollo mission artifacts to the newly erected building. Just outside, a replica of a Saturn V stands in a upright position. Similar rockets are being displayed at the Kennedy Space Centers in Florida and Huston, and at the Johnson Space Center, which completed its restoration only one year ago, at a cost of 5 million dollars.

Latino Women Are Genetically Predisposed to Preterm Pregnancy

We know that a 5-year-old Peruvian girl is the world's youngest mother and Latino women may not be very big. But a new study carried out at the Yale School of Medicine and presented at the Society for Maternal
Fetal Medicine Annual Meeting has discovered that the gene ENPP1 is connected to preterm birth and low birth weight in the case of the Hispanic women.

12 % of the American children are born prematurely (before 37 weeks of pregnancy). This is connected to health issues, especially in the case of children born before 28 weeks of pregnancy. It is unclear what causes the preterm births in most cases, but "both the genetic make-up of the mother and the genetic make-up of the baby play a role," said co-author Dr. Errol Norwitz, associate professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale.

African-American women had already been found to have a genetic predisposition to preterm births, even when socioeconomic status, demographics, medical history and multiple pregnancies were taken into account.

"Multiple genes or a single particular genetic variant—single nucleotide polymorphism—may be involved," said Norwitz.

The research team compared DNA from Hispanic mothers who had had preterm birth and women who had had only full-term pregnancies. The DNA for 128 different gene alleles (variations) was screened in 77 candidate genes. Those alleles were known to cause various conditions, but now they have been investigated for the first time in the context of preterm birth.

4 alleles were connected to premature birth, and one allele of the ENPP1 gene proved to be the strongest on causing preterm birth. ENPP1 was associated with insulin resistance and glucose intolerance (both linked to high predisposition to type-2 diabetes), and even to hardening of the arteries and hypertension.

"In the context of prematurity, it is possible that the variant form of ENPP1 is associated with deranged energy metabolism," wrote the researchers.

"In our original study, 85 % of the population was Hispanic. It appears that there are genetic variations unique to each ethnic population. We are now in the process of validating our findings in African-American, Caucasian and Native-American populations," said Norwitz.

This Mother Grows Her Kids Inside Her Stomach!

There's nothing impressive in this Australian frog: dull coloration and just up to 5.5 cm (2.2 in) in length. But the Rheobatrachus frogs, first described in 1973, are nothing ordinary.
Their name of gastric-brooding frogs speaks about an amazing breeding behavior in this species.

While keeping them in an aquarium, researchers were taken totally by surprise to see how one of the frogs opened her mouth and started to spit out froglets: 11 offspring in 50 minutes. Next day, the mother spat out another 15 offspring. The 26 froglets made 40 % of the body weight of their mother.

These frogs swallow their eggs after being spawn on the soil and fertilized by the male. The gastric gestation lasts 6-8 weeks, a period when the mother's stomach is swelling enormously. The female does not eat during this period, living on her own reserves. The lungs can no longer function due to the distorted stomach, and breathing is made exclusively through the skin. The gastric brooding increases the survival chances of the offspring: they are not exposed to predators or to the drying of the pool in which they live.

The puzzle is how the chlorhydric acid and digestive juices of the stomach do not destroy the eggs and the developing embryos. One hypothesis is that a part of the swallowed eggs sacrifice themselves for the development of the others, and during their break down, they release a chemical that blocks the hormone that determines the acidity of the gastric juice. That chemical was even detected: a prostglandin called PGE2, proved to be stable at temperatures varying between 30o C and -20oC.

Only two species of gastric brooding frogs WERE known from northeastern Australia, in an area of less than 2000 km² (800 mi²), in creek systems in rainforests between 350 – 1400 m (1100 - 4600 ft). By the mid 80's, both species disappeared, due to not clearly understood reasons. Hypotheses include habitat loss and degradation, pollution, and the amphibian Batrachochytrium dendrobatidis fungus.

NASA Says, ‘Hello, Universe. Meet the Beatles.’

If you’re out there in deep space, you’ll want to be tuning in at 7 p.m. Eastern time on Monday, Feb. 4 (plus however long it takes electromagnetic radiation to reach you from Earth doing the 186,000-miles-a-second speed limit).

That’s when NASA will be celebrating the 50th anniversary of its first space mission — the launch of the Explorer 1 satellite — by using the system of huge antennas that usually listen for inbound signals from space to send one outbound instead: the Beatles’ song “Across the Universe,” which as it happens was mostly recorded exactly 40 years earlier, on Feb. 4, 1968.

Reception will be best in the general direction of Polaris, 431 lightyears away, which is where NASA is aiming the signal. (That would be the North Star to us laymen.) But it ought to be audible in plenty of places on Earth as well, at least by imitation: NASA is encouraging space fans and Beatle fans alike to play the song themselves at the same time.

NASA’s press release includes some perfectly in-character comments from Sir Paul McCartney (”Amazing! Well done, NASA! Send my love to the aliens. All the best, Paul.”) and from Yoko Ono, widow of John Lennon, the song’s main author (”I see that this is the beginning of the new age in which we will communicate with billions of planets across the universe.”). Presumably, Julie Taymor will be pleased as well; her film “Across the Universe,” built around a soundtrack of Beatle songs, is still in theaters and contending for an Oscar; it is due for release on DVD on Tuesday.

The event also commemorates the 45th anniversary of the creation of the antenna system, the Deep Space Network, which NASA uses to explore space at one remove by listening to the electromagnetic radiation coming our way from Out There; the system also comes in handy for picking up data sent by space probes we have dispatched to the planets and beyond over the years.

NASA doesn’t often send outgoing mail this way; the last high-profile American broadcast meant specifically for extraterrestrial ears was also the first, dispatched by Professor Frank Drake of Cornell University in 1974 during the dedication of the upgraded Arecibo radiotelescope in Puerto Rico. (No reply, at least so far.) But Seth Shostak of the SETI Institute, which has been looking for signs of life beyond Earth since 1984, noted in an e-mail message to our colleague Dennis Overbye today that other groups in Ukraine and Canada have been sending signals in recent years.

Of course, vast amounts of electromagnetic signals flood out from the Earth every day as a side effect of ordinary human-to-human activity, from TV and radio broadcasts, radar stations, satellite uplinks and other sources, and the leading wave of that stuff has an eight-decade head start.

“Proof of our existence is already out there,” Dr. Shostak noted, “that’s simply a fact.”

An array of antennas that could pick up terrestrial TV signals in a distant solar system wouldn’t be hard to build, he observed. But there’s still plenty of time for any potential alien listener to tie-dye some T-shirts and stock the fridge before settling in to enjoy the song. Though scientists have found evidence of some 270 planets of other stars, most are extremely unlikely to support life, and all but a handful are far enough away that no readily detected, human-generated signal could yet have reached them.

“It’s safe to say that nobody knows of the existence of Homo sapiens (beyond this planet, of course),” Dr. Shostak observed.

A pity. The Lede was hoping for a little intergalactic help grokking that bit of Sanskrit in the chorus, “Jai guru deva om.”

9 Amazing Things About Llamas and Alpacas

1. Life in the Andes would be impossible without them. When a house is built on the Andes plateaus, people use to immure at its foundation a new born llama. For thousands of years, llamas have been used
for meat and burden transport, while its other domesticated relative, alpaca, delivered the finest wool for making blankets and ponchos (traditional mantles). A llama can transport up to 20 kg (44 pounds) of cargo.

2. Andean plateaus are of two types: wet paramos, between 3,800-4,600 m (12,600-15,300 ft) and dry punas, over 4,000 m (13,300 ft). Llama and alpacas thrive in the punas. A puna is characterized by low rainfall, extreme winds, powerful sunlight, rare and purified air. As an adaptation to these conditions, llamas and alpacas have dense and soft wool, thick skin, oval (not rounded) blood red cells.

3. Llamas and alpacas seem to have been domesticated in the area of the Lake Junin (Peru), around 2,500-1,750 BC.

4. Llamas were often sacrificed by Natives during their ceremonies, and even today the Indian fathers, with the occasion of the birth of a boy in their family, kill llamas or alpacas.

In the syncretic religion of the Andes, inside the churches, next to statues of the Catholic saints, you can see terracotta statues of llamas. During the Inca period, there were llama caravans made of 25,000 animals.

5. Llamas and alpacas are raised in conditions of semi-liberty. During the night, the animals are sheltered in open pens, surrounded by walls that keep some of the day's heat. Next morning, the animals go by themselves to graze and return to the pen at sunset. Through selection, people achieved alpacas with the hair long to the ground.

Cattle, horses or sheep could not adapt to puna conditions, with high temperature differences between day and night and poor food conditions.

6. Llama can have a hight of 1.3 m (4.3 ft), a length of 2 m (6.6 ft) and weight of 450 pounds (204 kg). Gestation lasts 11 months and the only offspring is raised for 15 months.

7. The Andean Indians use a system of knots made on the llama coat to transmit various messages and information.

8. One alpaca can deliver 3 kg (7 pounds) of wool at every two years. Alpaca is smaller than llama; it can be just 90 cm (3 ft) tall. 3 million individuals are found in Peru and about 50,000 in Bolivia, but attempts to colonize this animal, possessing the most expensive wool in the world, have failed so far in other areas.

9. Llamas and alpacas are closely related to camels. Like camels, they can spit as a method of establishing hierarchy, especially during the feeding time, as a way of disciplining lower-ranked individuals in the herd. Females also spit to chase away insistent males. The second type of spit is less smelly.

Blue Eyes: A Mutation Appeared 10,000 Years Ago!

Nature played with one of our ancestors, and it caused the blue eye color to appear; and now, women are in love with the blue eyes of Brad Pitt and men with those of Kristanna Loken. And that ancestor lived 6,000-10,000 years ago, as found by a research carried out at the University of Copenhagen.

"Originally, we all had brown eyes. But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a 'switch', which literally 'turned off' the ability to produce brown eyes ", said Professor Eiberg from the Department of Cellular and Molecular Medicine.

The OCA2 gene encodes the P protein, which controls the synthesis of
melanin, the pigment protein that gives the color of our hair, eyes and skin. The mutation is found in the gene adjacent to OCA2 that controls the activity of OCA2 and does not turn off completely the OCA2. It just decreases its action of spurring melanin synthesis in the iris, so that the low amount of melanin in the iris appears as blue, and not brown.

If the OCA2 gene had been silenced completely, the result would have been a total lack of melanin in hair, eyes or skin, a disease called albinism. In this case, the eyes would have been red, due to the blood vessels of the iris.

Eye color variation from brown to green is caused by the variable amount of iris melanin, but blue eyes are correlated with a very low level of variation in the melanin levels of the eyes, strictly linked to one genetic variation.

"From this we can conclude that all blue-eyed individuals are linked to the same ancestor. They have all inherited the same switch at exactly the same spot in their DNA," said Eiberg.

Oppositely, brown eyes can be the result of a large variation in the DNA sector controlling the melanin synthesis. The team investigated mitochondrial DNA (coming always from the maternal line) from blue-eyed individuals coming from countries far from one another, such as Jordan, Denmark and Turkey.

In 1996, the same team had detected that OCA2 was involved in the eye color. The mutation from brown eyes to blue eyes is another example of neuter mutation; like hair color or baldness, it does not impact the individual’s survival ability.

The First Dog Mummies Ever Found in Egypt!

In the heaven of the tomb raiders, an American-Russian team has managed to find 4 ancient tombs with well-preserved mummies, ornate painted coffins, and mummified dogs. The necropolis of Deir el-Banat is located in the oasis El Faiyum, 50 mi (80 km) southwest of Cairo, a place also famous for the discoveries of the oldest elephant fossils, some 50 million years old. Given the intensity of looting in the area, this was a surprise. The cemetery was used from the 4th century B.C. to the 7th century A.D.

"An important point is that these mummies are almost untouched. There are not so many [well preserved] mummies in El Faiyum at the moment," said lead researcher Galina A. Belova, a Russian Egyptologist.

In a separate tomb, the team found the first intact mummy ever encountered
in the necropolis. About 150 other tombs from different periods and a great number of poorly preserved mummies were also discovered, but most of the them had been plundered.
"Some of the newly discovered remains are the best yet found from the Ptolemaic era (the era of Greek domination that started soon after the conquest of Egypt by Alexander the Great in 332 B.C.). One mummy was beautifully gilded, and another is in very good condition," Zahi Hawass, Secretary General of Egypt's Supreme Council of Antiquities, told National Geographic News.

An odd burial contained the non-mummified remains of a child and several mummified dogs, unique in Egypt. The four best kept of the newly found tombs host almost intact human-shaped coffins.

"Some showed slight damage near the feet, probably the result of ancient robbers rummaging for riches," said the researchers.

The coffins were decorated with verses and images from the Egyptian Book of the Dead, crucial for the ancient Egyptians to pass from this world to the other. Three of them were wooden, while the fourth coffin, of a child, was made of papyrus, and was located on a different angle from the others.

"The shared burial may have belonged to a single family. It is uncommon to find coffins set at different orientations in this region," said the researchers.

Two coffins hosted mummies covered at the head and feet with vividly colored cartonnage. One mummy had a golden cartonnage mask, a symbol of eternity. One tomb also contained the only intact mummified woman that escaped from the tomb looters. As the tombs in this cemetery are less than a meter (3.3 ft) below the surface, they make easy targets for thieves.

The most interesting finding was the non-mummified body of a child having next to it mummified dogs. The child was naturally mummified by the dry climate, while the dogs were crudely mummified, and varied from puppies to adult dogs.

"They are put in any which way, with no real sense of orientation. Ancient Egyptians were known to keep domesticated pets and sometimes were buried with them. Other animals were included in burials as part of a religious ritual, but this find is unlike any that has been documented," said Salima Ikram, an animal mummy expert at the American University in Cairo.

Astronomers Capture Images of Asteroid

Astronomers have obtained the first images of an asteroid on course to make its closest approach to Earth Tuesday, showing the space rock is lopsided.

The new images, taken with the Goldstone Solar System Radar Telescope in California's Mojave Desert, refine estimates of the asteroid's size. Named 2007 TU24, the asteroid was estimated to span up to 2,000 feet, but is now thought to have a diameter of about 800 feet.

Scientists at NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif., have determined that there is no possibility of an impact with Earth in the foreseeable future.

As the asteroid moved nearer to Earth, on Jan. 28, the Arecibo Observatory in Puerto Rico working with the Robert C. Byrd Green Bank Telescope in West Virginia produced another image of the asteroid. Astronomers used the Arecibo telescope, which is operated by Cornell University on behalf of the National Science Foundation, to bounce radar signals off the asteroid. The Green Bank Telescope received the echo signal and transmitted the data back to Arecibo to be transformed into an image.

Other radar telescopes were expected to point toward the asteroid as it made its closest approach to Earth, 334,000 miles, at 3:33 a.m. Eastern time Tuesday. For comparison, the moon is an average of 239,228 miles away.

At its nearest, the asteroid will reach an approximate apparent magnitude 10.3, or about 50 times fainter than an object visible to the naked eye in a clear, dark sky. Then, it will quickly get fainter as it moves away.

The combination of these telescopes will provide higher resolution images of the asteroid. Measurements from Arecibo's radar telescope will gauge the object's size more precisely, its speed and spin.

Like other asteroids, this one orbits the sun. Most do so in the asteroid belt between Mars and Jupiter. NASA pays particular attention to those whose orbits bring them so close to Earth.

TU24, discovered by NASA's Catalina Sky Survey on Oct. 11, 2007, is one of an estimated 7,000 near-Earth objects identified to date (another 7,000 are estimated to exist but are yet to be discovered).

"We have good images of a couple dozen objects like this, and for about one in 10, we see something we've never seen before," said Mike Nolan, head of radar astronomy at the Arecibo Observatory. "We really haven't sampled the population enough to know what's out there."

10 Things You Did Not Know About Sea Shore

1. The shore seems to be the edge of the continent, but that's not true: the continents continue under the sea, on a strip edging each continent, and called continental shelf. How much of the continental shelf is covered by the sea depends on how much ice is stocked in the Polar Ice.

2. Around 10,000 years ago, the polar ice caps were much larger and the sea level was much lower, so that Britain was united to Europe and Alaska to Siberia. The melting of the ice at the end of the Ice Age raised the sea level by 7 mm annually. In 10,000 years, this meant 7 m (23 ft). The Dover Strait of the English Channel, 36 m (120 ft) deep, was covered by sea 8,000 years ago. Behring Strait between Alaska and Siberia is at least 45 m (150 ft) deep.

The shore line has continuously changed along the Earth's history. The line coast is also modified by the tectonic movements. The Pacific plate enters continuously under the South American one (process called subduction), through a deep sinkhole near the
shore. Andes Mountains descend abruptly close to the shore, and in some places, there is no shore. These slow changes occur along millions of years.

3. Waves' action can be seen from one year to another. Waves are caused by winds and influenced by the tides. Tides are caused by the gravitational force of the Moon. The Moon attracts the water mass beneath; this way the high tide emerges. The low tide appears when Moon force does not act. There are differences between the levels of the tide between Full Moon and New Moon, when the Moon and the Sun are located on the same ax with the Earth, on one side or another. In this situation, the gravitational forces sum. This happens twice a month. The tides are minimal when the gravitational force of the Moon makes a right angle with the gravitational force of the Sun. This also happens twice a month, when the Moon is found in its first and last quarter.

4. Most shores experience two high tides daily. In some regions, like southeastern Asia, this happens just once a day. Tides are very small on lakes and seas surrounded by lands, like the Great Lakes of North America and the Mediterranean Sea. Baltic and Black Sea do not have tides (almost) at all.

5. Hurricanes and other devastating storms produce killer waves, but the most devastating are those produced by underwater earthquakes, called tsunamis. If the tsunami strikes a shallow shore, its height can reach 25 m (83 ft) and destroys everything on land.

6. Sea currents and waves use sand and gravel to grind the shore continuously, destroying its rock base. Soft rocks are destroyed faster. If the base of the rock coast is eroded by waves, the upper parts will crumble. The broken rocks are taken by the waves. The best transporting waves are the short and abrupt ones which emerge close to the shore during the winter storms. They can have a force of 10 kg per square meter. Summer storms produce longer, stretched waves away of the shore. These waves carry more sand and gravel to the shore than what they bring back at the return, so that they actually build a new shore, not destroy it. Some destruction and construction can occur on the same place, like in Cap Canaveral (Florida), where waves build a new gulf while nearby they form a peninsula.

The action angle of the waves affects the sedimentation and abrasion of the waves. When waves reach the shore under certain angles, they depose sediments. The sea takes from one place and deposes onto another. This way, the length of Cape Cod, Massachusetts, is growing.

The grinding of soft rocks creates caves, rock tunnels, and if their roof crumbles, then blowers appear. In some places, waves dig chambers in the sides of the peninsulas. In time, the chambers can join each other, forming an abrasive gait or a spectacular rock bridge.

7. In Netherlands, over 1900 km (1190 mi) of dikes and sand dunes protect fertile land against sea flooding. Amsterdam and Rotterdam are located on islands recovered from the sea, called polders. In 1927, Dutch people started to transform the huge golf Zuider Zee in fertile land. A 32 km (20 mi) long dam at his entrance turned into a freshwater lake: Ijsellmeer. Dikes marked inside the lake 5 large polders, water being pumped out of them. Soil was washed of salt, and now agriculture is practiced there.

8. Islands are of two main categories. Some separate from a continent, like Great Britain and Ireland. These islands are located on continental shelves and if sea level decreased, they would be connected to the mainland.

Other islands are volcanic: they are the top of volcanoes raising from the sea bottom. This is the case of Hawaii or Azores Archipelagos.

9. Coral islands form over submarine volcanoes, sometimes, edging the submarine volcanoes, raising very little above the water. They only form in warm waters, being produced by the calcareous skeleton of tiny animals called coral polyps. The polyps form colonies of millions of individuals to a maximum depths of 30 m (100 ft). After their death, their skeletons form the coral banks. If the bank forms at the edge of a crater, the island has a ring shape and is called atoll. The atoll surrounds a saltwater lagoon. The ring breaks in several places, so that the lagoon is directly connected to the sea. Broken coral transforms into calcium carbonate sand. This will form the base of the soil on coral islands. On the external part of the atoll, the shore is thin and the sea deepens abruptly. On the inner side, the shore is more gentle and most lagoons are shallow.

Coral barriers form at a certain distance from the shore and between them and the shore there is a long lagoon. The coral barrier, too, can be interrupted, especially close to river mouths (corals lack in these areas because the sediments discharged by the rivers kill them; they need clean waters for their photosynthetic symbiont algae). The most famous is the Australian Great Coral Barrier, next to Queensland (northeastern Australia).

10. Mangrove forests appear in tropical coasts devoid of powerful waves.

Sex Makes You Dumber!

Sex and studying do not get along. The more sex partners you have, the more prone you are to academic failure, as found by a new survey made amongst students at Cambridge University.
The on-line questionnaires completed by over 1,000 undergraduates revealed that poorly performing colleges had the most sexually active students.

Peterhouse, one of the least performing Cambridge colleges, won the bronze of the promiscuity: these students had an average of five sexual partners annually compared to three at Christ’s College, a silver at Cambridge college as concerns the academic performances. Over 25 % of the Christ’s students stated they were virgin, this college is the Cambridge champion on the issue.

The results, published in the student magazine Varsity, also revealed which subjects delivered more sexually active students than others. Sex champions were the medicine students, since they had the highest average number of sexual partners (8), opposite to theology, with 2. Social political science won the second place (7 annual partners), history the third (6), followed by modern and medieval languages (5).

More sex does not seem to be correlated with a more intelligent behavior. Even if 40 % of the students had at least a one-night stand, over 60 % had never made tests for HIV, chlamydia or other sexually transmitted diseases.

"The more sociable a person is the less time they have for their studies. People who have a lot of sexual partners not only spend time initiating relationships with people but they also have to contend with a lot of stress when those relationships break up. This can seriously affect a person’s ability to concentrate," said Cary Cooper, a professor of psychology and health at Lancaster University.

"Some results confirm long-held stereotypes. Those involved in postgraduate study are less likely to have had sex than their undergraduate counterparts. It suggests that as long as you believe in sex before marriage, you will have lost your virginity by the time you graduate," said Ed Cumming, Varsity’s associate editor.

"It’s obvious that the mathematicians haven’t found the winning formula yet. But it’s good to see that doctors and nurses is still a popular game," said student union president Mark Fletcher.

8 Amazing Things About Plants

1. Plants have in their structure xylem tubes that transport water and mineral salts and phloem tubes that carry the food. Both types of tubes are produced by a meristematic tissue called cambium. Xylem is produced inward, phloem outward. Death xylem layers form the wood.

2. The green pigment called chlorophyll allows the photosynthesis through which plants synthesize sugars coming from water and carbon dioxide. Even brown or red leaves contain chlorophyll. Only parasite plants, like dodders and fungi lack chlorophyll. Sugars stock sun energy. In greenhouses, artificial light and supplementary carbon dioxide boost photosynthesis. But plants also need nitrogen, phosphorus, magnesium, iron, calcium and potassium, plus minor amounts of other elements, for synthesizing all the necessary organic chemicals. Most plants store energy as starch.

3. Plants breathe all the time, breaking down the sugars for getting energy. Plants also sweat, mainly through their leaves. Water goes out through small pores called stoma. This creates an absorption force transmitted to the roots. In wet environments, plants sweat less, but in dry, windy areas,
the water loss is high. Plants adapted to dry and hot weather lack leaves (cacti) or have special changes in their leaves that impede water loss, like thick cuticles and less stoma whose opening can be controlled.

4. Plants growing in the shadow have larger leaves; plants can also direct their leaves towards the light source, a phenomenon called phototropism. Because plants lack a nervous system, plants' reactions are controlled by hormones. Gibberellins are involved in stimulating plants' growth, while abscisic acid inhibits the plant growth, causing the leaves and mature fruits to fall.

Geotropism is the plant's reaction to gravitation: their roots always grow downward. Chemotropism is the plant's reaction to chemicals, like auxins, hormones that control plants' development and the growth rate of various parts. Auxins are concentrated in roots and shoots. Too much auxin inhibits the growth. If a plant is placed horizontally, auxins accumulate in the lower part, causing the curbed vertical growth of the plant.

Auxins are more concentrated in the shadowed part of the plant; this way they stimulate those cells to grow more rapidly, turning the shoot towards the light. This is a method through which a hormone creates movement. Auxins are involved also in the opening of the flowers, being influenced by light and temperature. Heat makes the petals grow faster causing the opening of the blossoms while the cold can revert this process.

In vines, the growth hormones concentrate into the opposite side to the support, fact that causes the curly growth around the support. As auxins control the shoots' development, they generate the bushy (or not) aspect of a plant. When shoots are cut or destroyed, the auxins levels decrease, turning on "sleeping" buds that produce new shoots.

5. Plants growing in the tropical areas experience relatively short daylight all round the year, while those from higher latitudes experience very long daylight during the vegetation time in the summer. That's why tropical plants cultivated in temperate areas, like Dahlia brought from Mexico, will flower during the shorter autumn days.

6. Today, there are about 400,000 species of plants. First plants going out of the water (mosses and ferns) are still connected to wet environments, due to physiological and reproductive reasons. First flowered plants (gymnosperms) depended on wind for pollination and seed dispersal. Angiosperms (fruit plants) evolved with the pollinating insects.

7. The oldest known "plants" are 3.1 billion years old blue-green "algae" (a type of photosynthetic bacteria). These plants still form scums on lawns or forest trails and are the first organisms to have made photosynthesis. Bacteria can divide in 20-30 minutes, and a sole cell can produce hundreds of millions of bacteria in 10 hours. Most bacteria have about 0.00001 mm in length.

8. About 1.5 billion years ago, the first real unicellular algae appeared. They still make most of the phytoplankton. Euglena, a unicellular alga, can also feed the way animals do. Today, unicellular algae grow from the oceans to lakes and wet places (like shadowed walls). 590 million years ago, there were over 900 species of large pluricellular algae ("sea weeds"). Likens are symbioses between an alga and a fungus. They are so resistant, that they can live at 5,600 (19,000 ft) in Himalaya and are the first pioneers of barren rocks or colonize tree trunks or bones. Some likens are used for achieving turnsole, a chemical indicator that turns red in acid solutions and blue in alkaline solutions.

440 million years ago, freshwater algae started to conquer the land. They got rigid tissues and the vascular tubes (xylem and phloem). Their bodies still resembled an alga body, lacking roots or leaves, and reproduced through spores that required humidity. These early vascular plants inhabited swamps.

Mosses have structures resembling leaves or stems, but they do not have vascular tissues and are strictly connected to wet places.

In ferns, the sporophyte is less dependent on humidity, but the gametophyte developing from the spores requires humidity. 360 million years ago, huge tree ferns related to the horse tails united in extensive forests that formed coal deposits. Pteridosperms (seed ferns) appeared 248 million years ago, they resembled ferns, but eliminated the gametophyte, producing seeds on the tip of their branches.

Gymnosperms have seeds, but do not form fruits. They dominated the Mesozoic Era, when dinosaurs ruled the Earth, starting about 290 million years ago, when Earth was dominated by Ginkgo relatives, coniferous trees, and Cycas relatives. Redwoods, which are coniferous gymnosperms, are the world's largest trees.

Most living plants are angiosperms and angiosperms make (almost) all our plant food (if we except some alga intake), from cereals to fruits and vegetables. They appeared 140 million years ago, during the Cretaceous (the last dinosaur era), and since then, they have been dominating the world's vegetation. Angiosperms have the seed wrapped in a fruit, and are adapted to various pollinators and methods of seed dispersal.

Women Have Thicker Skulls Than Men!

Men are bigger than women and they have a reputation as being more thick-headed than the females. And here comes the surprise delivered by a new research published in the International Journal
of Vehicle Safety: in fact, women have thicker skulls then men!

The team made of researchers from the Ford Motor Co. and Tianjin University of Science and Technology developed a non-invasive method of measuring geometric traits of the human skull. The researchers investigated head scan images of 3,000 patients at the Tianjin Fourth central Hospital (China).

The results amazed them: the average thickness of women's skulls is 7.1 mm (0.28 in), 9 % higher than the average value of 6.5 mm (0.25 in) for men. Still, men's skulls were found to be 3 % larger in front-to-back distance (an average of 6.9 in (176 mm) compared to 6.7 in (171 mm) of the women) and 4 % wider than the female skulls (5.7 in (145 mm) compared to 5.5 in (140 mm)). It also appeared the skulls of both women and men slowly lose thickness after reaching adulthood.

These discoveries will have, beside scientific value, a practical use in designing helmets or other devices that could more effectively protect the head in case of vehicle collisions and other types of accidents.

"Skull thickness differences between genders are confirmed in our study. The next step will be to find out how these differences translate into head impact response of male and female, and then we can design the countermeasure for head protection," said co-author Jesse Ruan, a Ford biomechanics researcher.

"While a thicker skull provides more protection in a head injury, skull shape is also a factor. It will take more research to determine which feature is more important. Reliable biomechanical geometric data of the human skull can help us to better understand the problem of head injury during an impact," wrote the researchers.

DNA Molecules Display Telepathy-like Quality

DNA molecules can display what almost seems like telepathy, research now reveals.

Double helixes of DNA can recognize matching molecules from a distance and then gather together, all seemingly without help from any other molecules, scientists find. Previously, under the classic understanding of DNA, scientists had no reason to suspect that double helixes of the molecule could sort themselves by type, let alone seek each other out.

The spiraling structure of DNA includes strings of molecules called bases. Each of its four bases, commonly known by the letters A, T, C and G, is chemically attracted to a specific partner — A likes binding to T, and C to G. The scheme binds paired strands of DNA into the double helix the molecule is famous for.

Scientists investigated double-stranded DNA tagged with fluorescent compounds. These molecules were placed in saltwater that contained no proteins or other material that could interfere with the experiment or help the DNA molecules communicate.

Curiously, DNA with identical sequences of bases were roughly twice as likely to gather together as DNA molecules with different sequences.

The known interactions that draw the bases together are not the factor bringing these double helixes close. Double helixes of DNA keep their bases on their insides. On their outsides, they have highly electrically charged chains of sugars and phosphates, which obscure the forces that pull bases together.

Although it looks as if spooky action or telepathic recognition is going on, DNA operates under the laws of physics, not the supernatural.

To understand what researchers conjecture is really happening, think of double helixes of DNA as corkscrews. The bases that make up a strand of DNA each cause the corkscrew to bend one way or the other. Double-stranded DNA with identical sequences each result in corkscrews "whose ridges and grooves match up," said researcher Sergey Leikin, a physical biochemist at the National Institute of Child Health and Human Development in Bethesda, Md.

The electrically charged chains of sugars and phosphates of double helixes of DNA cause the molecules to repel each other. However, identical DNA double helixes have matching curves, meaning they repel each other the least, Leikin explained.

The scientists conjecture such "telepathy" might help DNA molecules line up properly before they get shuffled around. This could help avoid errors in how DNA combines, errors that underpin cancer, aging and other health problems. Also, the proper shuffling of DNA is essential to sexual reproduction, as it helps ensure genetic diversity among offspring, Leikin added.

Leikin and his colleagues will detail their findings in the Jan. 31 issue of the Journal of Physical Chemistry B.

The Ocean's Biological Deserts Are Expanding

The Sahara, the Gobi, the Chihuahuan--all are great deserts. But what about the South Pacific's subtropical gyre? This "biological desert" within a swirling expanse of nutrient-starved saltwater is the largest, and least productive, ecosystem of the South Pacific. Together with the subtropical gyres in other oceans, biological deserts cover 40% of Earth's surface. But their relative obscurity may be about to change. Researchers are reporting that the ocean's biological deserts have been expanding, and they are growing much faster than global warming models predict.

The evidence comes from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) onboard the orbiting SeaStar spacecraft. Launched in 1997, SeaWiFS maps ocean color around the globe. The green of the photosynthetic pigment chlorophyll a is a measure of the abundance of plant life, which supports the base of the food chain. In an upcoming Geophysical Research Letters paper, biological oceanographer Jeffrey Polovina of the U.S. National Marine Fisheries Service in Honolulu, Hawaii, and his colleagues describe how they charted the changing size of the central region of faintest green in the subtropical gyres of the North and South Pacific, North and South Atlantic, and South Indian oceans from SeaWiFS's launch through 2006.

All of the biological deserts had grown, except the South Indian Ocean's. The total expansion was 6.6 million square kilometers or 15%, and it happened as the shallow waters of the gyres were warming. "We're seeing this pattern in each of the four ocean basins," says Polovina. That suggests to him that global warming could be the ultimate cause of the observed desert expansion.

Gyre waters are already strongly layered, so stirring by the wind brings little of the nutrients stored in deep waters to the surface to fuel plant and ultimately animal growth. Warming further strengthens this stratification, making such nourishing mixing all the more difficult. Climate-ecosystem models predict that global warming will exacerbate ocean desert expansion, but not this quickly, Polovina notes. During the past 9 years, gyre deserts expanded 10 to 25 times faster than modeled.

The trend feels solid to other scientists. "Everything seems to hold together," says SeaWiFS project scientist Charles McClain of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who was not affiliated with the study. A variety of oceanographic observations and modeling is consistent with warming driving the expansion of the gyres and their low-productivity waters, he says. A lingering question, he adds, is whether part or even all of the expansion might be just a natural variation that could reverse itself in a decade or two. "We can't rule that out," says Polovina. One thing's for sure: Given the limited lifetimes of orbiting spacecraft, SeaWiFS won't be around long enough to find out.