Dark matter is originally hypothesized to explain the abnormally high rotation speeds of galaxies which would otherwise be torn apart if they did not contain hidden mass. (Google Photo)

US astronomers claim to have observed dark matter--the elusive substance that is believed to be five times as common as normal matter, accounting for nearly a quarter of the universe, Physicweb said.
NASA’s Chandra X-ray Observatory, the Hubble Space Telescope, the European Southern Observatory’s Very Large Telescope and the Magellan optical telescopes were used to observe the violent collision between two large galaxy clusters 3 billion light years away. The force of the collision separated the dark and luminous matter, allowing a clear identification. Although scientists are yet to determine what form this mysterious dark matter may take, the observations are strong evidence that most of the matter in the universe is dark.
Dark matter was originally hypothesized to explain the abnormally high rotation speeds of galaxies, which would otherwise be torn apart if they did not contain hidden mass. It is fundamentally different from normal “luminous“ matter such as stars as it is invisible to modern telescopes, giving off no light or heat, and seems to interact only through gravity.
However, some scientists do not believe that dark matter exists and have proposed alternative theories--where gravity is stronger on intergalactic scales--to explain galactic dynamics. The new results are a blow to such theories. “Regardless of how one modifies gravity, it should still generally point to where most of the mass is,“ says Maxim Markevitch at the Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, who was involved in the research. “If the only matter in this cluster was visible matter, the mass map would approximately follow the interstellar gas map. Instead, we found most of the mass elsewhere, exactly where if it were dominated by collisionless dark matter.“
Behind these observations lies a remarkable bullet-shaped cloud of hot gas produced by the collision of two clusters. As they cross at 10 million miles per hour, the luminous matter in each interacts with the other and slows down. But the dark matter does not interact at all, passing right through without disruption. This causes the dark matter to sail ahead, separating each cluster into two components: dark matter in the lead and luminous matter lagging behind.
To detect this separation, researchers compared x-ray images of the luminous matter with measurements of the cluster’s total mass through gravitational lensing. This involves the observation of the distortion of light from background galaxies by the cluster’s gravity--the greater the distortion, the more massive the cluster. The team discovered four separate clumps of matter: two large clumps of dark matter speeding away from the collision, and two smaller clumps of luminous matter trailing behind, proving two types of matter exist.

At lower temperatures polymer molecules unravel and prevent the action of molecular motors (NewScientist Photo)

A way to stop and start molecular motors could make it easier to construct biosensors and devices on the nanoscale. The method uses heat to attach and detach cargo from molecular motors, thus bringing the tiny cargo to a halt, NewScientist wrote.
Nano-sized objects can be moved one at a time using laser tweezers or an atomic force microscope. But nanotechnologists interested in moving lots of tiny cargo at once are hoping that the molecular motors found in living cells could do the job.
The motors are attached to a surface and push certain proteins along by passing them from motor to motor, like people in a crowd with their arms outstretched passing an object from hand to hand. The motors simply need to be provided with the right fuel. Microscopic cargo can hitch a ride by attaching to the proteins and are carried along routes mapped out by a coating of motors.
“This could be used for all kinds of applications, like molecular sorting or nanofabrication, but it’s necessary to gain some outside control,“ nanotechnologist Stefan Diez at the Max Plank Institute, Germany, told New Scientist.
Diez and colleagues devised a new traffic method by mixing heat-sensitive polymer molecules into a coating of molecular motors made from the protein kinesin. Other proteins--long thin ones called microtubules--can be transported by the kinesin motors. The polymers can interfere with the movement of the microtubules, depending on the temperature.
In a watery environment the polymers absorb water and extend into long chains that prevent the microtubules from attaching to the kinesin motors, and also detach those that have already bound.
Above about 33¡C, however, and the polymers become unable to absorb water and curl into tight balls. Microtubules are then free to attach to the motors and glide along as usual.
The transport surface was made from silicon wafer coated with the heat-sensitive polymer, before adding a subsequent coating of kinesin molecules. This produced a surface covered in a mixture of motors and polymers.
“It should be possible to put small patches of this [mixed] surface alongside areas without the polymer,“ says Diez. If you had a track leading to a Y-junction you could shut one of the branches off, he says, simply by heating the system to more than 33¡C. This would prevent microtubules binding to motors down one fork, forcing them to head down the other.

A chemical found in the harder plastics that make up CD cases, water-cooler jugs and other objects people handle might help promote breast cancer, HealthDay quoted researchers as saying.
The chemical--a “pseudo-estrogen“ called bisphenol-A--appears to be preferentially absorbed by breast tumor cells.
While the new research doesn’t give any definitive answer on BPA’s potential role in breast cancer, American researchers say they have uncovered a biological mechanism that allows the compound to concentrate in tumor cells.
Healthy cells don’t readily absorb bisphenol sulfate, one of the body’s metabolized forms of BPA. So, many experts have assumed the chemical might be harmless.
However, “it turns out that breast tumor cells are different than normal cells,“ lead researcher Theodore Widlanski of Indiana University, said. “We showed that breast tumor cells actually convert bisphenol sulfate back into bisphenol-A, which can then be taken up into tumor cells.“
“These guys were aiming at what I’d say was the ’missing link,’“ added Patricia Hunt, a molecular bioscience professor at Washington State University who has conducted her own studies suggesting a link between BPA and birth defects in mice. “This is a first step, and a really important first step,“ she said.
The effects of BPA on human health--if any--have been hotly debated. Previous studies have linked even small exposures to prostate abnormalities in mice that suggest--but do not prove--a link between the plastics chemical and human prostate cancer.
Other studies, including Hunt’s, have theorized that embryonic and fetal exposures to BPA might trigger chromosomal changes that, in turn, could raise risks for mental retardation and birth defects.
BPA is a raw material used in the manufacture of hard, clear plastic products--everything from electronics parts to food-storage containers and baby bottles. It is not found in softer, more flexible products such as single-serving water bottles.
The chemical is known a “pseudo-estrogen“ because it is one of a number of natural or synthetic materials that can be taken into human cells and trigger estrogenic effects. But unlike estrogen, BPA undergoes chemical modifications as it enters the body, which makes its absorption by healthy human cells nearly impossible.
Specifically, the addition of a sulfate molecule to BPA keeps it from permeating the healthy cell’s outer membrane. But would the same phenomenon hold true for malignant cells, researchers wondered?
In a laboratory study using human breast cancer cell lines, the Indiana researchers, along with scientists from the University of California at Berkley, found that BPA appeared to concentrate in tumor cells.

The memory of mice suffering from Alzheimer’s disease has been restored, a study shows. US scientists increased the activity of an enzyme called Uch-L1 which is involved in memory function, BBC reported.
They then tested the mice and found that they had regained the ability to form new memories.
Writing in the journal Cell, the team said the work was in its early stages, but could help the development of therapies for the debilitating disease.
The scientists used transgenic mice that had Alzheimer’s disease. Like humans with the condition, the mice had plaques of protein amyloid beta in their brain and damaged synapses (the site where brain cells communicate with each other), and they also suffered from memory loss.
The researchers injected the mice with a substance which boosted levels of the enzyme Uch-L1.
They then tested the mice’s memory by putting them into a cage where they were exposed to a very mild shock from the cage floor.
Mice with normal memories stay still when they are placed in the cage for a second time, to avoid the shock, whereas mice with Alzheimer’s do not because they cannot remember their first visit.
The researchers found that when they placed the mice with boosted Uch-L1 levels into the cage, they stayed still like the normal mice.
Dr Ottavio Arancio, an author on the paper from Columbia University’s Taub Institute for Research on Alzheimer’s Disease and Aging, said: “We injected the mice with this enzyme, and we found we were restoring their memories.“
He said further investigation revealed the enzyme also seemed to repair the synapse function of the mice.
Michael Shelanski, another author on the paper from Columbia University, said: “While amyloid beta is certainly a key player in Alzheimer’s disease--and efforts to reduce it remain a worthy goal--our results show that, even in the presence of the plaque, damage to memory can be reversed.“
The authors propose that the enzyme could be targeted to look for new therapies for Alzheimer’s disease; however they cautioned that the research is in its early stages.
Dr Shelanski said: “While this discovery is very promising, its proven effectiveness is limited to animal models and it will take some time before it could lead to therapies in humans.
“We continue to work towards that crucial goal.“
In an accompanying commentary, Peter Lansbury, a neurobiologist from Harvard Medical School, Massachusetts, said: “Understanding the molecular mechanism of memory is one of the most compelling and complex challenges for the next generation of scientists.

Alopecia areata is an autoimmune disease characterized by sudden, recurrent hair loss in round spots from the scalp or any part of the body that has hair. (Google Photo)

People with a patchy form of hair loss called alopecia areata might be helped with hypnosis, a preliminary study suggests.
“Hypnotherapy may enhance the mental well-being of patients with alopecia areata and it may improve clinical outcome,“ Dr. Ria Willemsen, of Free University in Brussels, and colleagues write in the Journal of the American Academy of Dermatology, Reuters reported.
Alopecia areata is an autoimmune disease characterized by sudden, recurrent hair loss in round spots from the scalp or any part of the body that has hair. Psychological factors, such as stressful events and psychotrauma have also been reported to play a role in the onset of the condition, but few studies have looked at the efficacy of psychological treatments.
Willemsen’s team explored hypnosis as a treatment for 21 individuals with extensive hair loss on 30 percent or more of their scalp that had lasted for at least three months. These patients, all of whom previously failed to respond to treatment with steroids, were followed for anywhere from six months to six years.
In most cases, the study participants received hypnosis along with some other medical treatment. During the hypnotherapy sessions, which took place once every three weeks, study participants were given various suggestions, such as to imagine the healing effects of the sun’s warmth on their scalp.
After treatment with a minimum of just three to four sessions of hypnotherapy, 12 patients experienced hair growth on at least 75 percent of their scalp, and nine of these 12 experienced total hair growth, Willemsen and colleagues report.
None of the patients reported any negative side effects due to the hypnotherapy. Yet, five study participants experienced a significant relapse during the follow-up period, four of whom experienced enough hair loss to return them to their pretreatment status, the researchers note.
In other findings, all of the patients for whom the pertinent data was analyzed scored lower on a measure of psychological symptoms, including phobia, hostility and interpersonal sensitivity, after their hypnotherapy treatment. They also scored lower on items that specifically looked at symptoms of anxiety and depression, study findings indicate.
Exactly how hypnosis might stimulate hair growth is unknown. In the past, researchers have shown that the hypnotic suggestion to improve blood flow in the scalp was linked to an actual increase in blood flow and skin temperature of the scalp. Willemsen and colleagues speculate that hypnosis may also indirectly lead to certain immune system changes.
Still, despite the findings, the researchers maintain that it “is still controversial“ whether hypnosis is an effective treatment for alopecia areata. Since most patients received hypnotherapy as an add-on treatment, “it is not possible to evaluate how much of the changes and improvement in the hair growth was caused by the hypnotic interventions,“ they write.