3D Printing: Food in Space

3D Printing

NASA and a Texas company are exploring the possibility of using a "3D printer" on deep space missions in a way where the "D" would stand for dining.

NASA has awarded a Small Business Innovation Research (SBIR) Phase I contract to Systems and Materials Research Consultancy of Austin, Texas to study the feasibility of using additive manufacturing, better known as 3D printing, for making food in space. Systems and Materials Research Consultancy will conduct a study for the development of a 3D printed food system for long duration space missions. Phase I SBIR proposals are very early stage concepts that may or may not mature into actual systems. This food printing technology may result in a phase II study, which still will be several years from being tested on an actual space flight.

As NASA ventures farther into space, whether redirecting an asteroid or sending astronauts to Mars, the agency will need to make improvements in life support systems, including how to feed the crew during those long deep space missions. NASA's Advanced Food Technology program is interested in developing methods that will provide food to meet safety, acceptability, variety, and nutritional stability requirements for long exploration missions, while using the least amount of spacecraft resources and crew time. The current food system wouldn't meet the nutritional needs and five-year shelf life required for a mission to Mars or other long duration missions. Because refrigeration and freezing require significant spacecraft resources, current NASA provisions consist solely of individually prepackaged shelf stable foods, processed with technologies that degrade the micronutrients in the foods.

Additionally, the current space food is selected before astronauts ever leave the ground and crew members don't have the ability to personalize recipes or really prepare foods themselves. Over long duration missions, a variety of acceptable food is critical to ensure crew members continue to eat adequate amounts of food, and consequently, get the nutrients they need to maintain their health and performance. 

NASA is funding this phase I six-month $125,000 study on 3D printing of foods to determine the capability of this technology to enable nutrient stability and provide a variety of foods from shelf stable ingredients, while minimizing crew time and waste. NASA selected this proposal because the research team, subcontractors and consultants included premier food rheology and flavor expertise that would be required for a novel product development system. The work plan for this feasibility study also was well laid out and the technology offers the potential to meet some of the food requirements using basic food components for long duration missions. 

NASA recognizes in-space and additive manufacturing offers the potential for new mission opportunities, whether "printing" food, tools or entire spacecraft. Additive manufacturing offers opportunities to get the best fit, form and delivery systems of materials for deep space travel. This's why NASA is a leading partner in the president's National Network for Manufacturing Innovation and the Advanced Manufacturing Initiative. 

3D printing is just one of the many transformation technologies that NASA is investing in to create the new knowledge and capabilities needed to enable future space missions while benefiting life here on Earth. 

Source:

www.nasa.gov

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Comet Lovejoy Plunges into the Sun and Survives

COMET LOVEJOY

This morning, an armada of spacecraft witnessed something that many experts thought impossible. Comet Lovejoy flew through the hot atmosphere of the sun and emerged intact.

"It's absolutely astounding," says Karl Battams of the Naval Research Lab in Washington DC. "I did not think the comet's icy core was big enough to survive plunging through the several million degree solar corona for close to an hour, but Comet Lovejoy is still with us."

The comet's close encounter was recorded by at least five spacecraft: NASA's Solar Dynamics Observatory and twin STEREO probes, Europe's Proba2 microsatellite, and the ESA/NASA Solar and Heliospheric Observatory. The most dramatic footage so far comes from SDO, which saw the comet go in (below) and then come back out again (above).

In the SDO movies, the comet's tail wriggles wildly as the comet plunges through the sun's hot atmosphere only 120,000 km above the stellar surface. This could be a sign that the comet was buffeted by plasma waves coursing through the corona. Or perhaps the tail was bouncing back and forth off great magnetic loops known to permeate the sun's atmosphere. No one knows.

"This is all new," says Battams. "SDO is giving us our first look at comets traveling through the sun's atmosphere. How the two interact is cutting-edge research."

"The motions of the comet material in the sun's magnetic field are just fascinating," adds SDO project scientist Dean Pesnell of the Goddard Space Flight Center. "The abrupt changes in direction reminded me of how the solar wind affected the tail of Comet Encke in 2007 (view movie)."

Comet Lovejoy was discovered on Dec. 2, 2011, by amateur astronomer Terry Lovejoy of Australia. Researchers quickly realized that the new find was a member of the Kreutz family of sungrazing comets. Named after the German astronomer Heinrich Kreutz, who first studied them, Kreutz sungrazers are fragments of a single giant comet that broke apart back in the 12th century (probably the Great Comet of 1106). Kreutz sungrazers are typically small (~10 meters wide) and numerous. The Solar and Heliospheric Observatory sees one falling into the sun every few days.

At the time of discovery, Comet Lovejoy appeared to be at least ten times larger than the usual Kreutz sungrazer, somewhere in the in the 100 to 200 meter range. In light of today's events, researchers are re-thinking those numbers.

"I'd guess the comet's core must have been at least 500 meters in diameter; otherwise it couldn't have survived so much solar heating," says Matthew Knight. "A significant fraction of that mass would have been lost during the encounter. The remains are probably much smaller."

SOHO and NASA's twin STEREO probes are monitoring the comet as it recedes from the sun. It is still very bright and should remain in range of the spacecrafts' cameras for several days to come.

What happens next is anyone's guess.

"There is still a possibility that Comet Lovejoy will start to fragment," continues Battams. "It' been through a tremendously traumatic event; structurally, it could be extremely weak. On the other hand, it could hold itself together and disappear back into the recesses of the solar system."

"It's hard to say," agrees Knight. "There has been so little work on what happens to sungrazing comets after perihelion (closest approach). This continues to be fascinating."

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Tour the Cygnus X Star Factory

Cygnus X

Cygnus X hosts many young stellar groupings. The combined outflows and ultraviolet radiation from the region's numerous massive stars have heated and pushed gas away from the clusters, producing cavities of hot, lower-density gas.

In this 8-micron infrared image, ridges of denser gas mark the boundaries of the cavities. Bright spots within these ridges show where stars are forming today.

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Radiation and Health

How does radiation cause health effects?

Radioactive materials that decay spontaneously produce ionizing radiation, which has sufficient energy to strip away electrons from atoms (creating two charged ions) or to break some chemical bonds. Any living tissue in the human body can be damaged by ionizing radiation in a unique manner. The body attempts to repair the damage, but sometimes the damage is of a nature that cannot be repaired or it is too severe or widespread to be repaired. Also mistakes made in the natural repair process can lead to cancerous cells. The most common forms of ionizing radiation are alpha and beta particles, or gamma and X-rays.

What kinds of health effects does exposure to radiation cause?

In general, the amount and duration of radiation exposure affects the severity or type of health effect. There are two broad categories of health effects: stochastic and non-stochastic.

Stochastic Health Effects

Stochastic effects are associated with long-term, low-level (chronic) exposure to radiation. ("Stochastic" refers to the likelihood that something will happen.) Increased levels of exposure make these health effects more likely to occur, but do not influence the type or severity of the effect.

Cancer is considered by most people the primary health effect from radiation exposure. Simply put, cancer is the uncontrolled growth of cells. Ordinarily, natural processes control the rate at which cells grow and replace themselves. They also control the body's processes for repairing or replacing damaged tissue. Damage occurring at the cellular or molecular level, can disrupt the control processes, permitting the uncontrolled growth of cells--cancer. This is why ionizing radiation's ability to break chemical bonds in atoms and molecules makes it such a potent carcinogen.

Other stochastic effects also occur. Radiation can cause changes in DNA, the "blueprints" that ensure cell repair and replacement produces a perfect copy of the original cell. Changes in DNA are called mutations.

Sometimes the body fails to repair these mutations or even creates mutations during repair. The mutations can be teratogenic or genetic. Teratogenic mutations are caused by exposure of the fetus in the uterus and affect only the individual who was exposed. Genetic mutations are passed on to offspring.

Non-Stochastic Health Effects

Non-stochastic effects appear in cases of exposure to high levels of radiation, and become more severe as the exposure increases. Short-term, high-level exposure is referred to as 'acute' exposure.

Many non-cancerous health effects of radiation are non-stochastic. Unlike cancer, health effects from 'acute' exposure to radiation usually appear quickly. Acute health effects include burns and radiation sickness. Radiation sickness is also called 'radiation poisoning.' It can cause premature aging or even death. If the dose is fatal, death usually occurs within two months. The symptoms of radiation sickness include: nausea, weakness, hair loss, skin burns or diminished organ function.

Medical patients receiving radiation treatments often experience acute effects, because they are receiving relatively high "bursts" of radiation during treatment.

Is any amount of radiation safe?

There is no firm basis for setting a "safe" level of exposure above background for stochastic effects. Many sources emit radiation that is well below natural background levels. This makes it extremely difficult to isolate its stochastic effects. In setting limits, EPA makes the conservative (cautious) assumption that any increase in radiation exposure is accompanied by an increased risk of stochastic effects.

Some scientists assert that low levels of radiation are beneficial to health (this idea is known as hormesis).

However, there do appear to be threshold exposures for the various non-stochastic effects. (Please note that the acute affects in the following table are cumulative. For example, a dose that produces damage to bone marrow will have produced changes in blood chemistry and be accompanied by nausea.)

Exposure (rem)	Health Effect	Time to Onset (without treatment)
5-10	changes in blood chemistry
50	nausea	hours
55	fatigue
70	vomiting
75	hair loss	2-3 weeks
90	diarrhea
100	hemorrhage
400	possible death	within 2 months
1,000	destruction of intestinal lining
	internal bleeding
	and death	1-2 weeks
2,000	damage to central nervous system
	loss of consciousness;	minutes
	and death	hours to days

• Estimating Risk
  This page describes how scientists estimate cancer and other health risks from radiation exposures.

How do we know radiation causes cancer?

Basically, we have learned through observation. When people first began working with radioactive materials, scientists didn't understand radioactive decay, and reports of illness were scattered.

As the use of radioactive materials and reports of illness became more frequent, scientists began to notice patterns in the illnesses. People working with radioactive materials and x-rays developed particular types of uncommon medical conditions. For example, scientists recognized as early at 1910 that radiation caused skin cancer. Scientists began to keep track of the health effects, and soon set up careful scientific studies of groups of people who had been exposed.

Among the best known long-term studies are those of Japanese atomic bomb blast survivors, other populations exposed to nuclear testing fallout (for example, natives of the Marshall Islands), and uranium miners.

• Decay Chains: Uranium Miners
  This page contains information on the risks of radon in mines to miners.

Aren't children more sensitive to radiation than adults?

Yes, because children are growing more rapidly, there are more cells dividing and a greater opportunity for radiation to disrupt the process. EPA's radiation protection standards take into account the differences in the sensitivity due to age and gender.

Fetuses are also highly sensitive to radiation. The resulting effects depend on which systems are developing at the time of exposure.

Effects of Radiation Type and Exposure Pathway

Both the type of radiation to which the person is exposed and the pathway by which they are exposed influence health effects. Different types of radiation vary in their ability to damage different kinds of tissue. Radiation and radiation emitters (radionuclides) can expose the whole body (direct exposure) or expose tissues inside the body when inhaled or ingested.

All kinds of ionizing radiation can cause cancer and other health effects. The main difference in the ability of alpha and beta particles and gamma and x-rays to cause health effects is the amount of energy they can deposit in a given space. Their energy determines how far they can penetrate into tissue. It also determines how much energy they are able to transmit directly or indirectly to tissues and the resulting damage.

Although an alpha particle and a gamma ray may have the same amount of energy, inside the body the alpha particle will deposit all of its energy in a very small volume of tissue. The gamma radiation will spread energy over a much larger volume. This occurs because alpha particles have a mass that carries the energy, while gamma rays do not.

Non-Radiation Health Effects of Radionuclides

Radioactive elements and compounds behave chemically exactly like their non-radioactive forms. For example, radioactive lead has the same chemical properties as non-radioactive lead. The public health protection question that EPA's scientists must answer is, "How do we best manage all the hazards a pollutant presents?"

Do chemical properties of radionuclides contribute to radiation health effects?

The chemical properties of a radionuclide can determine where health effects occur. To function properly many organs require certain elements. They cannot distinguish between radioactive and non-radioactive forms of the element and accumulate one as quickly as the other.

• Radioactive iodine concentrates in the thyroid. The thyroid needs iodine to function normally, and cannot tell the difference between stable and radioactive isotopes. As a result, radioactive iodine contributes to thyroid cancer more than other types of cancer.
• Calcium, strontium-90 and radium-226 have similar chemical properties. The result is that strontium and radium in the body tend to collect in calcium rich areas, such as bones and teeth. They contribute to bone cancer.

Estimating Health Effects

What is the cancer risk from radiation? How does it compare to the risk of cancer from other sources?

Each radionuclide represents a somewhat different health risk. However, health physicists currently estimate that overall, if each person in a group of 10,000 people exposed to 1 rem of ionizing radiation, in small doses over a life time, we would expect 5 or 6 more people to die of cancer than would otherwise.

In this group of 10,000 people, we can expect about 2,000 to die of cancer from all non-radiation causes. The accumulated exposure to 1 rem of radiation, would increase that number to about 2005 or 2006.

To give you an idea of the usual rate of exposure, most people receive about 3 tenths of a rem (300 mrem) every year from natural background sources of radiation (mostly radon).

What are the risks of other long-term health effects?

Other than cancer, the most prominent long-term health effects are teratogenic and genetic mutations.

Teratogenic mutations result from the exposure of fetuses (unborn children) to radiation. They can include smaller head or brain size, poorly formed eyes, abnormally slow growth, and mental retardation. Studies indicate that fetuses are most sensitive between about eight to fifteen  weeks after conception. They remain somewhat less sensitive between six and twenty-five weeks old.

The relationship between dose and mental retardation is not known exactly. However, scientists estimate that if 1,000 fetuses that were between eight and fifteen weeks old were exposed to one rem, four fetuses would become mentally retarded. If the fetuses were between sixteen and twenty-five weeks old, it is estimated that one of them would be mentally retarded.

Genetic effects are those that can be passed from parent to child. Health physicists estimate that about fifty severe hereditary effects will occur in a group of one million live-born children whose parents were both exposed to one rem. About one hundred twenty severe hereditary effects would occur in all descendants.

In comparison, all other causes of genetic effects result in as many as 100,000 severe hereditary effects in one million live-born children. These genetic effects include those that occur spontaneously ("just happen") as well as those that have non-radioactive causes.

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Protecting Against Exposure

What limits does EPA set on exposure to radiation?

Health physicists generally agree on limiting a person's exposure beyond background radiation to about 100 mrem per year from all sources. Exceptions are occupational, medical or accidental exposures. (Medical X-rays generally deliver less than 10 mrem).  EPA and other regulatory agencies generally limit exposures from specific source to the public to levels well under 100 mrem.  This is  far below the exposure levels that cause acute health effects.

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How does EPA protect against radionuclides that are also toxic? 

In most cases, the radiation hazard is much greater than the chemical (toxic) hazard. Radiation protection limits are lower than the chemical hazard protection limits would be. By issuing radiation protection regulations, EPA can protect people from both the radiation and the chemical hazard. However, deciding which hazard is greater is not always straightforward. Several factors can tip the balance:

• toxicity of the radionuclide
• strength of the ionizing radiation
• how quickly the radionuclide emits radiation (half-life)
• relative abundance of the radioactive and non-radioactive forms

For example:

• Uranium-238 is both radioactive and very toxic. Its half-life of 4.5 billion years means that only a few atoms emit radiation at a time. A sample containing enough atoms to pose a radiation hazard contains enough atoms to pose a chemical hazard.  As a result, EPA regulates uranium-238 as both a chemical and a radiation hazard.
• Radioactive isotopes of lead are both radioactive and toxic. In spite of the severe effects of lead on the brain and the nervous system, the radiation hazard is greater. However, the radioactive forms of lead are so uncommon that paint or other lead containing products do not contain enough radioactive lead to present a radiation hazard.  As a result, EPA regulates lead as a chemical hazard.

Source : Epa.gov

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New Material Can Enhance Energy, Computer, Lighting Technologies

Ball and Stick Model

Arizona State University researchers have created a new compound crystal material that promises to help produce advances in a range of scientific and technological pursuits.

ASU electrical engineering professor Cun-Zheng Ning says the material, called erbium chloride silicate, can be used to develop the next generations of computers, improve the capabilities of the Internet, increase the efficiency of silicon-based photovoltaic cells to convert sunlight into electrical energy, and enhance the quality of solid-state lighting and sensor technology.

Ning's research team of team of students and post-doctoral degree assistants help synthesize the new compound in ASU's Nanophotonics Lab in the School of Electrical, Computer and Energy Engineering, one of the university's Ira A. Fulton Schools of Engineering.

The lab's erbium research is supported by the U.S. Army Research Office and U.S. Air Force Office of Scientific Research. Details about the new compound are reported in the Optical Materials Express on the website of the Optical Society of America.

The breakthrough involves the first-ever synthesis of a new erbium compound in the form of a single-crystal nanowire, which has superior properties compared to erbium compounds in other forms.

Erbium is one of the most important members of the rare earth family in the periodic table of chemical elements. It emits photons in the wavelength range of 1.5 micrometers, which are used in the optical fibers essential to high-quality performance of the Internet and telephones.

Erbium is used in doping optical fibers to amplify the signal of the Internet and telephones in telecommunications systems. Doping is the term used to describe the process of inserting low concentrations of various elements into other substances as a way to alter the electrical or optical properties of the substances to produce desired results. The elements used in such processes are referred to as dopants.

"Since we could not dope as many erbium atoms in a fiber as we wish, fibers had to be very long to be useful for amplifying an Internet signal. This makes integrating Internet communications and computing on a chip very difficult," Ning explains.

"With the new erbium compound, 1,000 times more erbium atoms are contained in the compound. This means many devices can be integrated into a chip-scale system," he says. "Thus the new compound materials containing erbium can be integrated with silicon to combine computing and communication functionalities on the same inexpensive silicon platform to increase the speed of computing and Internet operation at the same time."

Erbium materials can also be used to increase the energy-conversion efficiency of silicon solar cells.

Silicon does not absorb solar radiation with wavelengths longer than 1.1 microns, which results in waste of energy -- making solar cells less efficient.

Erbium materials can remedy the situation by converting two or more photons carrying small amounts of energy into one photon that is carrying a larger amount of energy. The single, more powerful photon can then be absorbed by silicon, thus increasing the efficiency of solar cells.

Erbium materials also help absorb ultraviolet light from the sun and convert it into photons carrying small amounts of energy, which can then be more efficiently converted into electricity by silicon cells. This color-conversion function of turning ultraviolet light into other visible colors of light is also important in generating white light for solid-state lighting devices.

While erbium's importance is well-recognized, producing erbium materials of high quality has been challenging, Ning says.

The standard approach is to introduce erbium as a dopant into various host materials, such as silicon oxide, silicon, and many other crystals and glasses.

"One big problem has been that we have not been able to introduce enough erbium atoms into crystals and glasses without degrading optical quality, because too many of these kinds of dopants would cluster, which lowers the optical quality," he says.

What is unique about the new erbium material synthesized by Ning's group is that erbium is no longer randomly introduced as a dopant. Instead, erbium is part of a uniform compound and the number of erbium atoms is a factor of 1,000 more than the maximum amount that can be introduced in other erbium-doped materials.

Increasing the number of erbium atoms provides more optical activity to produce stronger lighting. It also enhances the conversion of different colors of light into white light to produce higher-quality solid-state lighting and enables solar cells to more efficiently convert sunlight in electrical energy.

In addition, since erbium atoms are organized in a periodic array, they do not cluster in this new compound. The fact that the material has been produced in a high-quality single-crystal form makes the optical quality superior to the other doped materials, Ning says.

Like many scientific discoveries, the synthesis of this new erbium material was made somewhat by accident.

"Similar to what other researchers are doing, we were originally trying to dope erbium into silicon nanowires. But the characteristics demonstrated by the material surprised us," he says. "We got a new material. We did not know what it was, and there was no published document that described it. It took us more than a year to finally realize we got a new single-crystal material no one else had produced."

Ning and his team are now trying to use the new erbium compound for various applications, such as increasing silicon solar cell efficiency and making miniaturized optical amplifiers for chip-scale photonic systems for computers and high-speed Internet.

"Most importantly," he says, "there are many things we have yet to learn about what can be achieved with use of the material. Our preliminary studies of its characteristics show it has many amazing properties and superior optical quality. More exciting discoveries are waiting to be made."

Source : Science Daily

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What Bacteria Don't Know Can Hurt Them

Bacteria

Inverse (Nov. 21, 2011) — Many infections, even those caused by antibiotic-sensitive bacteria, resist treatment. This paradox has vexedphysicians for decades, and makes some infections impossible to cure.

A key cause of this resistance is that bacteria become starved for nutrients during infection. Starved bacteria resist killing by nearly every type of antibiotic, even ones they have never been exposed to before.

What produces starvation-induced antibiotic resistance, and how can it be overcome? In a paper appearing this week in Science, researchers report some surprising answers.

"Bacteria become starved when they exhaust nutrient supplies in the body, or if they live clustered together in groups known as biofilms," said the lead author of the paper, Dr. Dao Nguyen, an assistant professor of medicine at McGill University.

Biofilms are clusters of bacteria encased in a slimy coating, and can be found both in the natural environment as well as in human tissues where they cause disease. For example, biofilm bacteria grow in the scabs of chronic wounds, and the lungs of patients with cystic fibrosis. Bacteria in biofilms tolerate high levels of antibiotics without being killed.

"A chief cause of the resistance of biofilms is that bacteria on the outside of the clusters have the first shot at the nutrients that diffuse in," said Dr. Pradeep Singh, associate professor of medicine and microbiology at the University of Washington, the senior author of the study. "This produces starvation of the bacteria inside clusters, and severe resistance to killing."

Starvation was previously thought to produce resistance because most antibiotics target cellular functions needed for growth. When starved cells stop growing, these targets are no longer active. This effect could reduce the effectiveness of many drugs.

"While this idea is appealing, it presents a major dilemma," Nguyen noted. "Sensitizing starved bacteria to antibiotics could require stimulating their growth, and this could be dangerous during human infections."

Nguyen and Singh explored an alternative mechanism. Microbiologists have long known that when bacteria sense that their nutrient supply is running low, they issue a chemical alarm signal. The alarm tells the bacteria to adjust their metabolism to prepare for starvation. Could this alarm also turn on functions that produce antibiotic resistance?

To test this idea, the team engineered bacteria in which the starvation alarm was inactivated, and then measured antibiotic resistance in experimental conditions in which bacteria were starved. To their amazement, bacteria unable to sense starvation were thousands of times more sensitive to killing than those that could, even though starvation arrested growth and the activity of antibiotic targets.

"That experiment was a turning point," Singh said. "It told us that the resistance of starved bacteria was an active response that could be blocked. It also indicated that starvation-induced protection only occurred if bacteria were aware that nutrients were running low."

With the exciting result in hand, the researchers turned to two key questions. First does the starvation alarm produce resistance during actual infections? To test this the team examined naturally starved bacteria, biofilms, isolates taken from patients, and bacterial infections in mice. Sure enough, in all cases the bacteria unable to sense starvation were far easier to kill.

The second question was about the mechanism of the effect. How does starvation sensing produce such profound antibiotic resistance? Again, the results were surprising.

Instead of well-described resistance mechanisms, like pumps that expel antibiotics from bacterial cells, the researchers found that the bacteria's protective mechanism defended them against toxic forms of oxygen, called radicals. This mechanism jives with new findings showing that antibiotics kill by generating these toxic radicals.

The findings suggest new approaches to improve treatment for a wide range of infections.

"Discovering new antibiotics has been challenging," Nguyen said. "One way to improve infection treatment is to make the drugs we already have work better. Our experiments suggest that antibiotic efficacy could be increased by disrupting key bacterial functions that have no obvious connection to antibiotic activity."

The work also highlights the critical advantage of being able to sense environmental conditions, even for single-celled organisms like bacteria. Cells unaware of their starvation were not protected, even though they ran out of nutrients and stopped growth. This proves again that, even for bacteria, "what you don't know can hurt you."

The Burroughs Welcome Fund, the Cystic Fibrosis Foundation, the National Institutes of Health, and the Canadian Institutes for Health Research supported this research.

The results are contained in the Science article, "Active starvation responses mediate antibiotic tolerance in biofilms and nutrient-limited bacteria."

In addition to Nguyen and Singh, the researchers on the study were Amruta Joshi-Datar, Elizabeth Bauerle, Karlyn Beer, and Richard Siehnel of the Departments of Medicine and of Microbiology at the UW, James Schafhauser of McGill University, Francois Lepine of INRS Armand Frappier in Canada, Oyebode Olakanmi and Bradley E. Britigan of the University of Cincinnati, and Yun Wang of Northwestern University.

Source : Science Daily

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Famous Birth of Black Hole: The mystery of a long About Object Called Cygnus X-1 decomposed

Artist's conception of Cygnus X-1: black holes attract matter froma companion star (right) gets hot, rotating disk

For the first time, astronomers have produced a completedescription of a black hole, the concentration of mass so dense that even light can not escape the strong gravitational pull. Their exact measurements has allowed them to reconstruct the history ofthe object of his birth about six million years ago.

Using several telescopes, both ground-based and in orbit, scientists have unraveled the mystery of a long object called Cygnus X-1, a well-known binary star system was found to be strong X-ray emitting nearly half a century ago. This system consists of a black hole and companion star from which the black hole is drawing matter. Efforts of the scientists' produce the most accurate measurements ever of black hole mass and spin rate.

"Because there is no other information can escape from a black hole, knowing its mass, spin, and electric charge gives a full explanation about it," said Mark Reid, of the Harvard-Smithsonian Center for Astrophysics (CfA). "This accusation of black holes is almost zero, so that measuring the mass and spin to make us a complete description," he added.

Although the Cygnus X-1 has been studied intensively since its discovery, previous attempts to measure the mass and spin suffers from a lack of precise measurements of the distance from Earth. Reid led a team that used Very Long Baseline Array of the National Science Foundation (VLBA), the continent-wide radio telescope system, to make direct trigonometric measurement of distance. They VLBA observations give a distance of 6070 light-years, whereas previous estimates have ranged 5800-7800 light-years away.

Armed with the measurements, just the right distance, the scientists using the Chandra X-Ray Observatory, Rossi X-Ray Timing Explorer, Advanced Satellite for Cosmology and Astrophysics, and visible-light observations made during more than two decades, calculates that the black hole Cygnus in the X-1 is almost 15 times more massive than our Sun and rotate more than 800 times per second.

"This new information gives us strong clues about how the black hole was born, what were weighed and how fast it is spinning," said Reid. "Getting a good measurement of distance is very important," added Reid.

"We now know that Cygnus X-1 is one of the biggest black hole in Milky Way stars," said Jerry Orosz, from San Diego State University. "This black hole spin as fast as anything we've ever seen," he added.

In addition to measuring the distance, VLBA observations, made during 2009 and 2010, were also measured movement of Cygnus X-1 through our galaxy. That movement, the scientists said, is too slow for the black hole has been generated by supernova explosions. As the explosion will give the object a "kick" for higher speeds.

"There is a suggestion that black holes can be formed without a supernova explosion, and our results support the suggestion that," Reid said.

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Probiotic Protects Intestine from Radiation Injury

probiotic

Scientists at Washington University School of Medicine in St. Louis have shown that taking a probiotic before radiation therapy can protect the intestine from damage -- at least in mice.

The new study suggests that taking a probiotic also may help cancer patients avoid intestinal injury, a common problem in those receiving radiation therapy for abdominal cancers. The research is published online in the journal Gut.

Radiation therapy often is used to treat prostate, cervical, bladder, endometrial and other abdominal cancers. But the therapy can kill both cancer cells and healthy ones, leading to severe bouts of diarrhea if the lining of the intestine gets damaged.

"For many patients, this means radiation therapy must be discontinued, or the radiation dose reduced, while the intestine heals," says senior investigator William F. Stenson, MD, the Dr. Nicholas V. Costrini Professor in Gastroenterology & Inflammatory Bowel Disease at Washington University. "Probiotics may provide a way to protect the lining of the small intestine from some of that damage."

Stenson has been searching for ways to repair and protect healthy tissue from radiation. This study showed that the probiotic bacteria Lactobacillus rhamnosus GG (LGG), among other Lactobacillus probiotic strains, protected the lining of the small intestine in mice receiving radiation.

"The lining of the intestine is only one cell-layer thick," Stenson says. "This layer of epithelial cells separates the rest of the body from what's inside the intestine. If the epithelium breaks down as the result of radiation, the bacteria that normally reside in the intestine can be released, travel through the body and cause serious problems such as sepsis."

The researchers found that the probiotic was effective only if given to mice before radiation exposure. If the mice received the probiotic after damage to the intestinal lining had occurred, the LGG treatment could not repair it in this model.

Because the probiotic protected intestinal cells in mice exposed, the investigators believe it may be time to study probiotic use in patients receiving radiation therapy for abdominal cancers.

"In earlier human studies, patients usually took a probiotic after diarrhea developed when the cells in the intestine already were injured," says first author Matthew A. Ciorba, MD, assistant professor of medicine in the Division of Gastroenterology. "Our study suggests we should give the probiotic prior to the onset of symptoms, or even before the initiation of radiation because, at least in this scenario, the key function of the probiotic seems to be preventing damage, rather than facilitating repair."

The investigators sought to evaluate LGG's protective effects in a way that would leave little doubt about whether it was preventing injury, and if so, how it was protecting the cells that line the intestine.

"Some human studies have looked at the possibility that probiotics might reduce diarrhea, but most of those studies have not been quite as rigorous as we would like, and the mechanism by which the probiotics might work has not been addressed," Stenson says.

Previously, Stenson and his colleagues demonstrated that a molecular pathway involving prostaglandins and cyclooxygenase-2 (COX-2), key components in inflammation, could protect cells in the small intestine by preventing the programmed cell death, or apoptosis, that occurs in response to radiation.

They gave measured doses of LGG to mice, directly delivering the live bacteria to the stomach. They found it protected only mice that could make COX-2. In mutant mice unable to manufacture COX-2, the radiation destroyed epithelial cells in the intestine, just as it did in mice that didn't receive the probiotic.

"In the large intestine, or colon, cells that make COX-2 migrate to sites of injury and assist in repair," Ciorba says. "In this study, we evaluated that response in the small intestine, and we found that COX-2-expressing cells could migrate from the lining to the area of the intestine, called the crypt, where new epithelial cells are made, and we believe this mechanism is key to the protective effect we observed."

If human studies are launched, Ciorba says one bit of encouraging news is that the doses of probiotic given to mice were not exceptionally large, and their intestines were protected. So people wouldn't need mega-doses of the probiotic to get protection.

"The bacteria we use is similar to what's found in yogurt or in commercially available probiotics," he says. "So theoretically, there shouldn't be risk associated with this preventative treatment strategy any more than there would be in a patient with abdominal cancer eating yogurt."

In addition, he notes, future research is focused on isolating the particular radio-protective factor produced by the probiotic. When that is identified, a therapeutic could be developed to harness the probiotic benefit without using the live bacteria.

Funding for this research comes from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (NIH), the Crohn's and Colitis Foundation of America and a Global Probiotics Council Young Investigator Award given to Matthew A. Ciorba, MD.

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