In The Search For Dark Matter

The Exotic Particles Would Explain a Lot About the Universe, and That Promise Has Scientists Going Underground.

You might think an astrophysicist would spend much of his time with his head in the stars. Instead, Sean Paling often squeezes into a cage with a bunch of burly miners and travels for six minutes in darkness to the bottom of Britain's deepest working mine.

At a lab here, 3,300 feet underground, Dr. Paling is searching for one of the most elusive objects in the universe: a wimp, or weakly interacting massive particle. Wimps are leading candidates for dark matter, which is believed to account for up to 95% of the mass of the universe. Something that big would be easy to spot except for the fact that dark matter is invisible. That doesn't stop the elusive mass from making its presence felt by the immense gravitational tug it exerts on stars, galaxies and other cosmic bodies.

"For 20 years, the miners have been asking if I've found it yet, and for 20 years I've been saying no," says Dr. Paling, an astro-particle physicist at England's Sheffield University, who has been searching for wimps at Boulby since 1989. "You can understand their confusion."

Unraveling the secret of dark matter is one of the grandest prizes of astrophysics because it is the key to understanding the shape, size and even the fate of the universe. Knowing how much dark matter there is will tell us whether the universe will keep expanding, or expand to a point and then collapse, or get bigger and bigger and then stop. More parochially, it can help us predict how Earth's neighborhood, the Milky Way galaxy, formed and how it might evolve.

But it is a difficult quest. Wimps rarely interact with normal matter such as atoms; indeed, billions of wimps may be darting right through the Earth every second without hitting anything. Detectors must be installed deep underground because on the surface, the profusion of other cosmic rays would crowd out a wimp's signal, which is feeble, because wimps move relatively slowly.

Wimp hunts have been going on for years in the U.K., Italy, Spain and France, as well as at a disused iron mine in Minnesota. The race intensified in April, when scientists working beneath Italy's Gran Sasso mountain announced that they had found signals of dark matter streaming in from space, though the results are in dispute.

The newest competitor on the scene is the European Organization for Nuclear Research, or CERN, the group that runs Europe's new Large Hadron Collider outside Geneva. CERN scientists hope to find evidence of dark matter in a different way, by smashing together subatomic particles at high speed and seeing if any wimps emerge.

Which group will get there first? "It depends on who nature is kind to," says Tom Le Compte, a particle physicist at CERN and Argonne National Laboratory in Argonne, Ill.

The U.K. project is unusual because it is based in a working mine, a tough environment for an experiment that relies on minute measurements and ultra-clean, ultra-sensitive equipment. The 35-year-old potash mine, near England's northeast coast, has more than 620 miles of dark and dusty tunnels, including some that delve under the North Sea.

"Unlike the miners," says Dr. Paling, "we are ever so delicate."

Dr. Paling and his colleagues first set up an extremely basic wimp detector at the mine. In 2003, a £2 million ($3.1 million) investment got them a full-scale lab with far more sensitive machines. It is run by Sheffield University, Rutherford Appleton Laboratory and other British and international groups.
One recent morning, Dr. Paling donned miner's gear -- overalls, boots, helmet, lamp and respirator -- and took the ride down the shaft. As he and his colleagues walked to the lab, a grimy, salt-encrusted vehicle went rattling by, carrying a group of miners to an underground excavation area 30 minutes away.

Dr. Paling pointed upward and said: "You can't feel it, but only one-millionth of the cosmic rays hit you here, compared to on the surface. We expect some are wimps."

The dark-matter lab is a long, narrow structure, suspended by cables inside a cavern. There are places in the mine where the temperature reaches 111 degrees Fahrenheit. "It's because you're closer to hell," jokes David Pybus, a spokesman for Cleveland Potash Ltd., which operates the mine.

That day, in a tunnel far from the lab, a loud, remote-controlled excavator made a racket as it gnawed through the walls of a tunnel, spewing salt everywhere. To keep out such contaminants, the lab is protected by a series of doorways and air blowers. Also vital to the operation is a local "cleaning lady" with a mop and bucket.

Most wimp detectors contain a target material, typically a liquid or a solid that is particularly sensitive; one of the detectors at Boulby uses carbon disulfide gas. The hope is that a wimp of cosmic origin will fly through the surrounding rock and, if the scientists get really lucky, strike a particle of the target material. By studying the collision, a computer can tell whether the particle is a wimp or something else.

That is the challenge. Although the walls of the mine give off only very low amounts of radiation, the detector picks up the signals of alpha, gamma and other forms of radiation emitted by materials in the lab, including the detector itself. Dr. Paling and his colleagues struggle to keep these background effects to a minimum.

One of the current Boulby detectors is called Drift II, for directional recoil identification from tracks. It is specially designed to tap into something called the wimp wind. As the earth rotates on its axis and also zooms around the sun, there are times when a stream of wimps would be expected to come straight at you -- in your face, as it were -- and other times when the wind would be at your back. If scientists can detect such a modulation, it would be extra evidence for wimps, since such a directionally changing signal can't be mimicked by background sources.

On a computer screen, Dr. Paling watched as the detector registered a series of particle collisions. The first he dismissed as an alpha particle, based on the length of its track. Another turned out to be a gamma particle. No wimps today. Dr. Paling doesn't usually study each collision in real time, but inspects a record compiled by the computer.

If scientists armed with sufficiently sensitive detectors fully explore the range of possible wimp interactions with matter and still don't find the elusive particles, it would mean that wimps may not exist -- and some basic observations about the universe would have to be re-examined.

"A little doubt starts to occur in your mind now and again," Dr. Paling says. "Then you look at a galaxy that's rotating 10 times faster than is possible given the missing mass, and you know the wimps are out there."

Scientists Use Pigs to Try to Beat Cystic Fibrosis

WASHINGTON (Reuters) - U.S. scientists have created pigs that appear to develop cystic fibrosis just as people do, a step they hope will accelerate efforts to tackle the disease.

Writing in the journal Science on Thursday, scientists at the University of Iowa and the University of Missouri said they created genetically engineered piglets with the same mutation that causes cystic fibrosis in people.

Studying how the disease unfolds in these pigs may provide insights into cystic fibrosis that thus far have eluded scientists and could point toward new treatments or maybe even a cure, said Dr. Michael Welsh of the University of Iowa.

People get CF when they inherit two mutated copies of a gene called CFTR, which was pinpointed as the cause in 1989. The disease causes mucus to accumulate and clog some of the organs in the body, especially the lungs and pancreas.

The Cystic Fibrosis Foundation, which helped fund the study, said about 70,000 people worldwide, including 30,000 people in the United States, have CF. People with the disease can expect to live to about age 37.

Scientists create animal "models" of a disease in order to perform experiments that would not be possible with people. Mice with the genetic abnormality that causes cystic fibrosis have been developed, but the disease presents itself very differently in these rodents than in people.

"Unfortunately, the mice leave something to be desired," Welsh, who helped lead the study, said in a telephone interview.

"They don't get the pancreatic disease like people with CF get. They don't get the lung disease like people with CF get. They don't get the intestinal disease like people with CF get. There's been many questions that can't be answered," he added.

"The onset of these problems is difficult to track down in humans because sometimes they happen before birth or sometimes they happen silently," added Christopher Penland of the foundation.

This is the latest example of pigs used for human medical needs. For example, cardiac patients can get pig heart valves.

The scientists developed pigs with cystic fibrosis because their lungs have many characteristics of human lungs.

"Right now, if you want to do experiments to find treatments or therapies for the lung disease that is fatal for people with CF, you would have to experiment on kids that have CF," Randy Prather of the University of Missouri added.

The disease in pigs closely mimicked the initial stages of the disease seen in people. The scientists are waiting for them to develop lung disease typical of CF "so we can start experimenting in ways that have never been possible," Prather said in a statement.

Defibrillator Implants: Hard Choice for Patients

The implanted defibrillator, a device that can automatically shock an erratically beating heart back to a normal rhythm, has been proved to save lives. Hence its nickname: an emergency room in the chest. Major medical groups have recommended that more patients receive the devices.

But in the last two years the number of patients receiving defibrillators has actually declined, as more doctors and patients decide the risks and uncertainties the devices pose may outweigh their potential benefits.

This trend — the first decline since implanted defibrillators were introduced in 1985 — has spotlighted a shortcoming that health experts have struggled with for years. Simply put, there is no adequate tool or test to predict which of the heart patients who might seem good candidates to get the expensive devices are the ones most likely to ever need their life-saving shock. Defibrillators have undoubtedly saved the lives of tens of thousands of Americans. That is why insurers still typically pay for the devices and the surgical procedure to implant them, which can top $50,000 for each patient.

What makes many doctors and patients increasingly wary, though, is a string of highly publicized recalls in recent years, along with mounting evidence suggesting that a vast majority of people who get a defibrillator never need it.
Industry estimates and medical studies indicate that defibrillators have saved the lives of 10 percent of the more than 600,000 people in this country who have received them, at most. While survivors would no doubt take those odds, 9 of 10 people who get defibrillators receive no medical benefit. One big long-term medical study indicated the odds of a defibrillator saving a patient’s life might be even slimmer — about 1 in 14, over the five-year period studied.

The problem that defibrillators pose is in some ways singular among medical technologies. For devices like artificial knees, which improve lives but do not save them, few people would settle for only a 1 in 10 chance of success. For a potentially life-saving cancer drug, a patient might grasp at even much slimmer odds. Where defibrillators differ is that they are only a powerful standby — ready to intervene if necessary, but unlikely ever to be called into service.

If defibrillators were simply $50,000 life insurance policies, the relatively low rate of payoff might not matter much. But the long-shot statistics are significant to people who must weigh the risks of infection and malfunction after they have an electronic device anchored inside their hearts and its wires threaded through their arteries.

The slim odds also have large implications for the United States health care bill, adding billions of dollars annually to Medicare spending and to insurance payments. Dr. Larry A. Chinitz, director of the Heart Rhythm Center at New York University’s Langone Medical Center, said, “The answer isn’t just to keep implanting everybody” who fits the current guidelines.

More doctors are now thinking twice. From a peak of 160,000 new patients in 2005, the number has fallen to less than 140,000 last year, according to Lawrence H. Biegelsen, an analyst at Wachovia Capital Markets. He predicts this year’s total will end up even lower. For the manufacturers, the numbers translate to a decline in defibrillator sales to $3.94 billion in this country last year, down from $4.29 billion in 2005, Mr. Biegelsen said.

Only overseas, where defibrillators have been slower to catch on, has the number of new implants continued to rise, hitting a new sales high of $1.93 billion last year.

Many patients, of course, are grateful for their defibrillators. “It’s saved me at least four times, including two when I passed out completely,” Matthew M. Murray, a 55-year-old former engineer in Riverbank, Calif., said of his implant.

And some experts worry that the pendulum may have swung too far away from defibrillators — putting countless lives at risk among people with the heart abnormalities and ailments most likely to cause cardiac arrest. At least several hundred thousand people in this country have such conditions, and some estimates place the figure at more than a million.

Meltronic, the leading maker of defibrillators, contends that each day 500 deaths are caused by sudden cardiac arrests among people who meet the current medical guidelines for the devices but do not have them. The NBC journalist Tim Russert, who died earlier this year, reportedly suffered a heart attack after an artery was blocked. While Mr. Russert had a history of heart disease, his condition was not one for which a defibrillator would have been prescribed.

Dr. Eric N. Prystowsky, a nationally renowned heart rhythm specialist in Indianapolis, said every doctor in his field was haunted by individual cases, like that of a Purdue University graduate student who was referred to Dr. Prystowsky for a defibrillator. The student had an abnormally thick heart muscle, a known risk for sudden cardiac arrest.

“He kept putting it off,” Dr. Prystowsky said of the decision to get a defibrillator. “Six weeks later, his fiancée called to say he had been found dead in bed.”

Cases like that may be inevitable as long as doctors cannot give patients more certainty about whether a defibrillator will actually help them.

Better clues could be submerged in the medical records of the people who have gotten defibrillators over the decades. Three years ago, Medicare ordered the creation of a nationwide registry, or database, for implanted defibrillators. Overseen by two leading professional groups, the American College of Cardiology and the Heart Rhythm Society, the registry has amassed about 270,000 records from 1,500 hospitals. But the data mining has only recently begun, and results are not expected before 2010 at the earliest.

Particle Collider Test Successful

GENEVA) — The world's largest particle collider successfully completed its first major test by firing a beam of protons all the way around a 17-mile (27-kilometer) tunnel Wednesday in what scientists hope is the next great step to understanding the makeup of the universe.

After a series of trial runs, two white dots flashed on a computer screen indicating that the protons had traveled the full length of the US$3.8 billion Large Hadron Collider.

There it is," project leader Lyn Evans said when the beam completed its lap.

The startup was eagerly awaited by 9,000 physicists around the world who now have much greater power than ever before to smash the components of atoms together in attempts to see how they are made.

"Well done everybody," said Robert Aymar, director-general of the European Organization for Nuclear Research, said after the protons were fired into the accelerator below the Swiss-French border at 9:32 a.m. (0732 GMT).

The organization, known by its French acronym CERN, fired the protons — a type of subatomic particle — around the tunnel in stages, several kilometers (miles) at a time.

Now that the beam has been successfully tested in clockwise direction, CERN plans to send it counterclockwise. Eventually the two beams will be fired in opposite directions with the aim of smashing together protons to see how they are made.

The startup comes over the objections of some skeptics who fear the collisions of protons could eventually imperil the earth. The skeptics theorized that a byproduct of the collisions could be micro black holes, subatomic versions of collapsed stars whose gravity is so strong they can suck in planets and other stars.

"It's nonsense," said James Gillies, chief spokesman for CERN, before Wednesday's start.

CERN is backed by leading scientists like Britain's Stephen Hawking in dismissing the fears and declaring the experiments to be absolutely safe.
Gillies told the AP that the most dangerous thing that could happen would be if a beam at full power were to go out of control, and that would only damage the accelerator itself and burrow into the rock around the tunnel. But full power is probably a year away.

"On Wednesday we start small," said Gillies. "A really good result would be to have the other beam going around, too, because once you've got a beam around once in both directions you know that there is no show-stopper."

The LHC, as the collider is known, will take scientists to within a split second of a laboratory recreation of the big bang, which they theorize was the massive explosion that created the universe.

The project organized by the 20 European member nations of CERN has attracted researchers from 80 nations. Some 1,200 are from the United States, an observer country which contributed $531 million. Japan, another observer, also is a major contributor.

The collider is designed to push the proton beam close to the speed of light, whizzing 11,000 times a second around the tunnel. Smaller colliders have been used for decades to study the makeup of the atom. Less than 100 years ago scientists thought protons and neutrons were the smallest components of an atom's nucleus, but in stages since then experiments have shown they were made of still smaller quarks and gluons and that there were other forces and particles.

The CERN experiments could reveal more about "dark matter," antimatter and possibly hidden dimensions of space and time. It could also find evidence of the hypothetical particle — the Higgs boson — believed to give mass to all other particles, and thus to matter that makes up the universe.

Researchers Report Advances in Cell Conversion Technique

(From the New York Times)

Biologists at Harvard have converted cells from a mouse’s pancreas into the insulin-producing cells that are destroyed in diabetes, suggesting that the natural barriers between the body’s cell types may not be as immutable as supposed.

This and other recent experiments raise the possibility that a patient’s healthy cells might be transformed into the type lost to a disease far more simply and cheaply than in the cumbersome proposals involving stem cells.

The new field depends on capturing master proteins called transcription factors that control which sets of genes are active in a cell and thus what properties the cell will possess. Each type of cell is thought to have a special set of transcription factors.

Last year a Japanese biologist, Shinya Yamanaka, showed that by inserting four transcription factors into an adult cell he could return it to its embryonic state.

In a variation of this technique, a team led by Qiao Zhou and Douglas A. Melton at Harvard has now identified three transcription factors active in the insulin-producing beta cells of the pancreas.

They hitched the genes for these three factors onto a virus that infects another type of pancreatic cell, known as an exocrine cell. In mice made diabetic by a drug that kills beta cells, the transformed exocrine cells generated insulin, allowing the mice to enjoy “a significant and long-lasting improvement” in their diabetic state, the researchers are reporting Thursday in the journal Nature. Although many steps remain before the technique could be considered for human use.

Besides producing insulin, the transformed exocrine cells looked like beta cells and ceased making proteins typical of exocrine cells. But they did not organize themselves into the pancreatic structures known as islets where beta cells usually cluster. The researchers claim only to have made “cells that closely resemble beta cells.”

Even so, Robert Blelloch, a cell biologist at the University of California, San Francisco, said, the Harvard experiment was “a very nice story — it’s pretty impressive that you can make such a switch just by adding three factors to a quite different cell type.”

Last month Patrick Seale and Bruce Spiegelman of the Dana-Farber Cancer Institute in Boston showed how with a single transcription factor they could make white fat cells generate brown fat cells, a very different type of cell. The Harvard work “is not occurring in a vacuum, but it’s a very important piece of work,” Dr. Blelloch said.

Human Exoskeleton Suit Helps Paralyzed People Walk

By Ari Rabinovitch

HAIFA, Israel (Reuters) - paralyzed for the past 20 years, former Israeli paratrooper Radi Kaiof now walks down the street with a dim mechanical hum.
That is the sound of an electronic exoskeleton moving the 41-year-old's legs and propelling him forward -- with a proud expression on his face -- as passersby stare in surprise.

"I never dreamed I would walk again. After I was wounded, I forgot what it's like," said Kaiof, who was injured while serving in the Israeli military in 1988.
"Only when standing up can I feel how tall I really am and speak to people eye to eye, not from below."

The device, called ReWalk, is the brainchild of engineer Amit Goffer, founder of Argo Medical Technologies, a small Israeli high-tech company. Something of a mix between the exoskeleton of a crustacean and the suit worn by comic hero Iron Man, ReWalk helps paraplegics -- people paralyzed below the waist -- to stand, walk and climb stairs.

Goffer himself was paralyzed in an accident in 1997 but he cannot use his own invention because he does not have full function of his arms. The system, which requires crutches to help with balance, consists of motorized leg supports, body sensors and a back pack containing a computerized control box and rechargeable batteries.

User picks a setting with a remote control wrist band -- stand, sit, walk, descend or climb -- and then leans forward, activating the body sensors and setting the robotic legs in motion. "It raises people out of their wheelchair and lets them stand up straight," Goffer said. "It's not just about health, it's also about dignity."

EYE CONTACT

Kate Parkin, director of physical and occupational therapy at NYU Medical Centre, said it has the potential to improve a user's health in two ways.
"Physically, the body works differently when upright. You can challenge different muscles and allow full expansion of the lungs," Parkin said.

"Psychologically, it lets people live at the upright level and make eye contact."
Iuly Treger, deputy director of Israel's Loewenstein Rehabilitation Centre, said: "It may be a burdensome device, but it will be very helpful and important for those who choose to use it."

The product, slated for commercial sale in 2010, will cost as much as the more sophisticated wheelchairs on the market, which sell for about $20,000, the company said.

The ReWalk is now in clinical trials in Tel Aviv's Sheba Medical Centre and Goffer said it will soon be used in trials at the Moss Rehabilitation Research Institute in Pennsylvania. Competing technologies use electrical stimulation to restore function to injured muscle, but Argo's Chief Operating Officer Oren Tamari said they will not offer practical alternatives to wheelchairs in the foreseeable future.