Sunday, February 19, 2012

Neutrinos not so fast

neutrino
Neutrinos are tiny, ghostly particles zipping through everything, all the time. This image comes from a computer model that scientists built to help look for neutrinos. The yellow dots are photons, or particles of light, produced by a neutrino as it entered a detector. Credit: Lawrence Berkeley National Laboratory
In September, European scientists reported on tiny particles called neutrinos that traveled faster than the speed of light. Physicists, the scientists who study energy in all its forms, have long believed that nothing outpaces light in a race through empty space. Understandably, September’s announcement seemed too amazing to be true.
Skeptical scientists quickly started picking the experiment apart. In recent papers, they claim superluminal neutrinos seem too fast to be true because they probably are too fast to be true. (“Superluminal” means “faster than light.”) According to these scientists, the universal speed limit likely still stands at 670 million miles per hour, the speed of light.
The neutrinos left an underground laboratory in Switzerland and traveled more than 450 miles to an underground laboratory in Italy. Scientists who work on an Italian experiment called OPERA timed the neutrinos as being a smidgen faster than the blaze of light.
As they traveled, the superswift particles should have been losing energy in the form of radiation, say physicists from Boston University. OPERA’s measurements didn’t show the expected energy loss in the neutrino beam. As a result, the experiment’s results seem off, say the Boston duo.
“I would be ecstatic to see some kind of new physics coming from this experiment,” Andrew Cohen, one of the Boston University physicists, told Science News. But the radiation evidence wasn’t there. “It’s just hard to accommodate” the conclusion that the particles outraced light, he says. Cohen worked with his colleague Sheldon Glashow, who won a Nobel Prize in 1979.
A separate team of scientists in Italy conducted a follow-up neutrino experiment to look for the missing radiation, but it didn’t show. Cohen and Glashow’s study doesn’t completely disprove the results, but it does suggest something went awry in the original experiment.
“We’re pretty much convinced that the experiment is wrong,” Glashow told Science News. “But I don’t think anyone has identified the error, if there is an error, as of yet.”
Scientists do have some ideas. A French physicist in Grenoble wonders if some of the neutrinos in the beam started their trip earlier than the scientists think. And a physicist in England, Carlo Contaldi, suggests that the clocks used to time the neutrinos may have been out of sync with each other. Contaldi points out that gravity tugs harder on the Swiss clock than on the one in Italy, and as a result they may have been ticking at different times.
Contaldi told Science News that he’ll be able to check his idea once the OPERA team starts talking more about their work.
“Until further details come out as to how they did the various bits of their experiment,” he said, “it’s not clear how to proceed.”
The case of the superluminal neutrinos shows the progress of science, from an astonishing find to the grueling work of verifying the results. Even if the neutrinos do obey the speed limit, the OPERA results will have given scientists valuable knowledge about the behavior of supersmall, superfast neutrinos.
POWER WORDS (Adapted from the New Oxford American Dictionary)
neutrino A fast particle with almost no mass that rarely reacts with normal matter. There are three kinds of known neutrinos.
superluminal Faster than the speed of light.
particle A tiny portion of matter.
physics The study of energy, matter and the relationship between the two.
matter Something which occupies space and has mass. Anything with matter will weigh something on Earth.

Self-cleaning clothes

Scientists in China have developed cotton fabric that uses sunlight to rid clothes of stains and smells. Credit: istockphoto
Cleaning clothes usually requires soap and water to remove stains and smells, and a tumble in the dryer or an afternoon on the clothesline to dry. The time and energy needed to turn a heap of dirty laundry into a pile of clean clothes might make people wish for clothes that just clean themselves.
That wish is a step closer to coming true. Recent experiments show that cotton fabric coated with the right mixture of chemicals can dissolve stains and remove odors after only a few hours in the sun.
“The technology can be applied to all kinds of fabrics and their related products,” says materials scientist Mingce Long. He helped develop the treated cotton with his colleague Deyong Wu, both of China’s Shanghai Jiao Tong University.
The handy fabric gets its self-cleaning abilities from a chemical mixture that coats the cotton threads. The coating includes substances known as photocatalysts, which trigger chemical reactions in light. One of those photocatalysts, called titanium dioxide, helps sunscreen block the sun and is used as tattoo ink. Another, called silver iodide, is used for developing photographs.
Researchers have previously shown that titanium dioxide mixtures could remove stains in clothes — but with exposure to ultraviolet, not visible, light. (The waves of ultraviolet light are more energetic and shorter than those of visible light.) Other studies have demonstrated that silver iodide can speed up chemical reactions in sunlight.
“We knew that self-cleaning cotton fabrics with titanium dioxide coating had already been developed, but they cannot work, or they work weakly, under sunlight,” Long says. “If we want to use the fabrics in daily life, we must develop cotton that cleans itself under daylight.”
Long and Wu created just such a fabric, working for years to perfect the recipe for a liquid dip that left cotton coated with the titanium dioxide mixture. Then they added particles of silver iodide, which boosted the fabric’s self-cleaning ability in the sun. In laboratory tests, their creation was nearly seven times better at removing stains (and killing bacteria lurking in the clothing) than titanium dioxide alone.
The scientists can’t start selling their self-cleaning cotton just yet; scientists still need to make sure the coated cotton won’t harm those who wear it. Although titanium dioxide is used in some foods, recent experiments have shown that it can cause health problems if it gets in the lungs. So before the material can be worn, scientists need to find a way to make it safe.
Still, Long says that he hopes to wear self-cleaning clothes one day — and avoid having to do laundry. “Someday in the future, when I walk on the street,” he says, “I hope people are wearing self-cleaning clothes that originated from my technology.”
POWER WORDS (adapted from the New Oxford American Dictionary)
photocatalyst A substance that starts a chemical reaction when exposed to light.
chemical reaction A process that involves rearrangement of the molecules or structure of a substance, as opposed to a change in physical form.
titanium dioxide A white, unreactive, solid material that occurs naturally as a mineral and is used extensively as a white pigment.
silver iodide A yellow powder that darkens with exposure to light. It is used in photography and artificial rainmaking.

Osteoporosis drugs delivered wirelessly

Implanted microchip that releases medications on command tested in people

access
VANCOUVER — An implanted microchip that releases medication on command from wireless signals has been demonstrated in people for the first time using a drug for osteoporosis.
This tiny device, implanted under the skin, could be useful in treating many diseases that require taking medication regularly, scientists reported February 16 at the annual meeting of the American Association for the Advancement of Science.
“This opens up profound possibilities for improving the treatment of patients and the potential of telemedicine,” said Robert Farra, president of MicroCHIPS Inc., the company that funded and conducted part of the study. A paper describing the results was also published online February 16 in Science Translational Medicine by collaborators from MicroCHIPS, MIT, Harvard and Case Western University.
The idea behind a microchip that could release chemicals in the body at precise times was first developed by MIT scientists over a decade ago. But researchers needed to make sure that medications were well stored in the device. Also, the immune system tends to create a barrier of collagen around implanted devices, which could make it difficult for the drug to make it into the bloodstream.
In the new study, a device with individual doses of the drug teriparatide sealed inside was implanted under the waistline in eight women with osteoporosis. When the device’s microprocessor receives a wireless signal, a current runs through the microchip, breaking open the metal layers that contain a single dose of the drug.
About two months after the device was implanted — and after the immune system’s protective barrier had formed — wireless signals programmed the device to release daily doses of teriparatide. The drug, which increases bone mass, is usually given by injection.
Based on blood tests, the doses from the device appeared to bump up levels of a molecule called P1NP, which indicates bone building — evidence that teriparatide released from the microchip works as it should.
Still, there are technical limitations with this device. James Watson, a researcher in Bioengineering at University of California, San Diego, said that the consistency of the devices is a concern. One device didn’t release any medication in one of the original patients.
No side effects appeared in any of the study participants, Farra said. What’s more, many patients said they weren’t bothered by the device or had, in fact, forgotten about it.

Oceans set stage for human evolution

VANCOUVER — Scientists may now be able to explain one of the key events that shaped human history: why East Africa got drier starting around 2 million years ago, with forests giving way to grasslands on which Homo could further evolve. Ocean temperature changes, especially the arrival of a strong warm/cool difference along the equator in the Indian Ocean, could have triggered the change.
“Those gradients are responsible for shifting rainfall towards or away from East Africa,” said Peter deMenocal, a paleoclimatologist at the Lamont-Doherty Earth Observatory in Palisades, N.Y. He presented new details about his idea on February 17 at the annual meeting of the American Association for the Advancement of Science.
Researchers infer that East Africa, where humans first evolved, started shifting toward grasslands by looking at data on the proportion of fossils of grazing animals, which peaked around 1.5 million years ago. Around this time Homo began to develop new tools, diversify into new species and make its first tentative forays out of Africa.
But despite a raft of theories, scientists haven’t been able to explain what triggered the drying responsible for the shift to grasslands. The ocean gradient idea might do the trick, deMenocal said.
“At first blush it doesn’t seem intuitively obvious, but what controls rainfall in the tropics is where the warm water is,” he said. More rain occurs where the ocean is warmest, because water can more readily evaporate and fall back as rain.
deMenocal and his colleagues looked at deep-sea sediment cores, representing the last several million years, drilled across the Indian, Pacific and Atlantic oceans. Most strikingly, a site in the eastern Indian Ocean and another in the western Indian Ocean show temperatures tracking similarly until around 2 million years ago, when the eastern site warmed and the western site cooled. If so, then the cool waters off East Africa would have dried out that part of the continent, deMenocal said.
Next the scientists ran computer simulations that erased the east/west temperature difference and showed what might happen if temperatures were the same along the equator across the Indian Ocean. That change shut down a type of atmospheric circulation, making East Africa wetter than it is today.
Taken together, deMenocal said, “I think this is pretty solid evidence for a transition to more open conditions [in East Africa] at this time.” What kicked off the change in ocean temperatures, though, remains a mystery.
Other, more recent climate changes may have also shaped the course of human evolution, said Andrew Weaver, a climate scientist at the University of Victoria in Canada. At the conference he reported new simulations looking at climate changes that happened about 105,000 years ago, around the time modern humans, Homo sapiens, were moving out of Africa.
When the northern ice sheets dumped great icebergs into the ocean, freshening the water there, rain belts in Africa also shifted, Weaver reported. In this case, the change may have dried out much of northern Africa, compelling H. sapiens to leave its birth continent.

Carbon dioxide breaking down marine ecosystems

 
access

Carbon dioxide bubbling up from seafloor seeps lowers the pH and species diversity in surrounding areas. Such sites offer a preview of climate-related ecosystem change as oceans acidify. Bruno Iacono
VANCOUVER — If carbon dioxide emissions don’t begin to decline soon, the complex fabric of marine ecosystems will begin fraying — and eventually unravel completely, two new studies conclude.
The diversity of ocean species thins and any survivors’ health declines as the pH of ocean water falls in response to rising carbon dioxide levels, scientists from England and Florida reported February 18 at the annual meeting of the American Association for the Advancement of Science. What’s more, affected species aren’t restricted to those with shells and calcified support structures — features particularly vulnerable to erosion by corrosive seawater.
Jason Hall-Spencer of the University of Plymouth, England, and his colleagues have been collecting data from marine sites off Italy, Baja California and Papua New Guinea, where high concentrations of carbon dioxide percolate out of the seabed from volcanic activity below. Directly above these CO2 seeps, pH plummets to at least 7.8, a value that is expected to occur widely by 2100 and which is substantially lower than the normal level for the area, 8.1. These sites offer a preview of what may happen to seafloor ecosystems as CO2 levels continue to rise, causing ocean water pH to drop.
Compared with nearby normal-pH sites, species richness in low-pH zones was diminished by 30 percent, Hall-Spencer reported. “Coral and some algae are gone. And the sea urchins are gone,” he said. Fish may be present, but unlike in areas with a normal pH, they won’t deposit their eggs there.
Although seagrasses appear to survive just fine in the low-pH seawater, close inspection showed that fish had nibbled the fronds, Hall-Spencer found. He identified one likely explanation: At low pH, these grasses no longer produced the phenolic defense compounds that typically deter munching by grazing animals.
His team also transplanted a host of healthy marine species to sites along a gradient of pH values leading up to an Italian seep, then monitored the emigrants’ health for a year.
Even shelled animals initially survived from fall to spring, in some cases bumping up their calcification in an attempt to cope with the corrosive waters. The surprise, Hall-Spencer notes: When peak temperatures arrived in August, many transplanted corals and mollusks died “due to the double whammy effect of high CO2 and high temperature.”
In lab experiments, Chris Langdon of the University of Miami Rosenstiel School of Marine and Atmospheric Science and colleagues raised coral larvae at pH values representing the South Pacific today and at levels expected in 50 and 100 years. Compared with newly spawned larvae at normal pH, the metabolism of those raised in the lowest pH environment dropped 65 percent, Langdon reported.
“You can think of this” — the lowered metabolism — “as a ball and chain attached to the leg of every coral larva,” Langdon says. “It’s not killing it outright, but each will have to go through life dragging this ball and chain behind.” Langdon also found that the larvae’s ability to make energy from nutrients in the water also suffered in the reduced pH. “So it’s like they’re starving at the same time,” he said.
Finally, there was a 60 percent decline in the number of larvae that could settle out onto a simulated reef surface, Langdon reported. One reason may have to do with the effects of acidification on turf algae in their environment. These algae made less of two key pigments. Ordinarily, the pigments “call out to the larvae, saying this is a nice place to settle,” he explains.
In Papua New Guinea, Langdon found evidence that the same thing appears to be happening in the wild at CO2 seeps with comparable pH values.
Other scientists reported at the meeting that at some sites, such as along the West Coast of the United States, seawater regionally — and regularly — falls to a pH of 7.5 or lower owing to natural factors other than CO2 seeps. Such new data may explain the occasional catastrophic wipeouts of young farmed shellfish in recent years, notes Gretchen Hofmann of the University of California, Santa Barbara.

Friday, February 17, 2012

Saving Energy in Agricultural Activities

Irrigation
Pumping out water
There is a potential of about 25% to 35% improvement in the efficiency of these pump sets by affecting minor/major rectification and shifting to ISI marked pumps.
  • The larger valve helps to save electricity / diesel because less fuel and power is needed to draw water from the well.
  • The fewer the no. of bends and fittings in a pipe, more the electricity saves.
  • Sharp bends in the pipe leads 70 % more frictional loss than standard bends.
  • A farmer can save 15 liters of diesel every month simply by reducing the pipe height by 2 m. The pump works more efficiently when it is not more than 10 feet above the water level of the well.
  • Use good quality PVC suction pipe to save energy and save electricity up to 20 %.
  • Apply oil and grease to pump set regularly as recommended by the manufacture.
  • To improve the power factor and voltage use ISI marked shunt capacitor of right capacity with motor. This will also save the electricity.
  • Switch off the light of well in the day time.

Gene Therapy Helps People With Inherited Blindness See


dna strand

Treating Two Eyes Safe and Effective, New Study Confirms
By
WebMD Health News
Reviewed by Laura J. Martin, MD
Feb. 8, 2012 -- Functionally blind for many years, Tami Morehouse calls the gene therapy that partially restored her sight nothing short of a miracle.
Morehouse was the first of 12 patients with a rare congenital retinal disease to receive the experimental treatment in one eye three years ago, and she is one of just three who has now had the gene therapy in both eyes.
The 47-year-old Ohio social worker and mother of three says before having the treatment she worried everyday that she would lose what little sight she had left.
“This treatment literally gave me a much brighter future,” she says. “My world just lit up and I saw things much more clearly. Soon after the second treatment I went out to dinner with my husband and I looked down and thought, ‘Oh my gosh, I can see the glass sitting in front of me.’”

Gene Therapy Targets Eye Mutation

The study Morehouse took part in was among the first to show that gene therapy can improve vision in people with inherited blindness.
The updated findings prove that treating both eyes is safe and beneficial, says researcher Jean Bennett, MD, PhD, of the University of Pennsylvania.
Patients received injections of healthy copies of a dysfunctional gene into their eyes in an effort to get the cells to work better.
The injections worked so well that Bennett and colleagues plan to treat the second eyes of the remaining five children and four adults who took part in the original study.
“There was some concern that the first injection would set up an immune response, causing the body to reject the second injection,” Bennett says. “If that happened, the benefits to the first [treated] eye could be threatened.”
But that is not what happened.
After having the injections in their second eye, the three patients were better able to see in dim light, and two of the three were able to navigate obstacles in low-light situations.

Half of Patients No Longer Legally Blind

All of the patients had an inherited, degenerative retinal disease called Leber congenital amaurosis (LCA), which is caused by a mutation in the RPE65 gene and generally progresses to blindness by mid-adulthood.
Morehouse says her vision became worse with each of her three pregnancies.
By the time she reached her early 40s, she saw little light or color, and most objects looked like “dark, hazy, blurry blobs,” she says.
The treatment involved injections of a genetically engineered virus that carried a normal version of the RPE65 gene.
After the first injections, the vision of six of the 12 study participants improved to the point that they were no longer classified as legally blind.
“One of the children who took part in the original study was riding a bicycle within a year,” says study co-author Manzar Ashtari, PhD, of the Children’s Hospital of Philadelphia. “This is a child who used a cane and held on to adults to guide him before having the treatment.”
          The hope is that similar therapies targeting other mutations can be used to treat a large number of inherited diseases that cause blindness.
Katherine A. High, MD, of Children’s Hospital of Philadelphia, who also worked on the study, says there are now 200 known genetic mutations that cause vision loss.
Because LCA is a degenerative disease, there is also hope that the treatment may one day be used in very young children, or even babies, before vision loss has occurred.
“For many genetic diseases -- not just this one -- early intervention will hold the key to optimal outcomes,” High says.
Morehouse is most excited by this promise.
“If this treatment or treatments like this one can keep children from losing their vision in the first place and spare them the struggles that I had growing up, that is truly a miracle,” she says.

Sleeping sickness drug resistance mechanism identified


Trypanosoma parasite in blood
The study highlights how the sleeping sickness parasite is affected by drugs
Flickr/ILRI


[DOUALA, CAMEROON] UK researchers have discovered how the drugs that are currently used to treat sleeping sickness work at the molecular level, potentially opening the way to tackling growing resistance to the drugs.
Sleeping sickness (human African trypanosomiasis) is caused by Trypanosoma brucei parasites and is transmitted by the tsetse fly in Sub-Saharan Africa, where the disease affected around 30,000 people in 2011, according to the WHO.
This is a dramatic drop since 1998 when close to 300,000 people were estimated to have the disease.
But the five drugs available (suramin, pentamidine, eflornithine, melasoprol and nifurtimox) are expensive, highly toxic, require prolonged treatment periods and are increasingly becoming ineffective because of parasite resistance.
Until recently, the scientists did not know how these drugs work or how resistance to them emerges.
"The older drugs were introduced over 60 years ago," David Horn, a researcher at the London School of Hygiene and Tropical Medicine told SciDev.Net. "They were known to kill the parasites but nothing was known about their molecular mechanism."
Now this knowledge gap has been filled.
Horn's team used genetic screening to pinpoint exactly how the drugs enter and kill the parasite, on a cellular level, a move which may help tackle growing resistance and lead to the design of better drugs.
They found that the drugs enter the parasite via molecular 'pumps', and that resistance can emerge when the parasite mutates to change or remove the pumps.
"We now know what these pumps look like at the molecular level and we also know which pumps are indispensable [for the parasite's survival]," said Horn, lead author of the study, published in Nature last month (25 January).
"This means we can develop new, durable drugs that get into the parasite cell via the indispensable pumps."
The researchers also identified 50 genes involved in the action of the drugs.
Horn hopes to use the technique to screen new drugs that are undergoing clinical trials to understand how they kill trypanosomes, and how resistance might emerge, as well as for screening veterinary drugs.
"The livestock diseases caused by African trypanosomes exert a huge economic burden in Africa and drug resistance is also a problem here," he said.
Horn now intends to team up with African researchers in endemic countries to further study drug resistance patterns.
Michael Barret, a biochemical parasitologist at the University of Glasgow, United Kingdom, said these results could speed up understanding of why resistance develops, and help make new and better drugs.
"Such drugs are desperately needed," Barret said.

Idea could lead to cheap solar cells using plant waste


Grass clippings
Any waste vegetation can be used — even grass clippings
Flickr/Caro's Lines


Remote communities could eventually make their own solar cells using waste vegetation, thanks to a design developed by researchers in Switzerland and the United States.
The technology is inspired by photosynthesis. In plant cells, sunlight separates electrical charges with almost 100 per cent efficiency.
Electrical charges must also be separated to create currents in solar cells. For the past decade, researchers have attempted to make solar cells by extracting some of the molecules responsible for photosynthesis — known as photosystem-I (PS-I) — from plants to produce an electric current when exposed to light.
Earlier devices failed to generate much electricity. But a team led by Andreas Mershin at Massachusetts Institute of Technology, United States, now claims to have found a solution so simple it can be replicated in any lab.  
They have found a way of exposing more of the cell to the sun by creating a three-dimensional miniature 'forest' of zinc oxide nanowires and titanium dioxide sponges on a layer of glass, coated with PS-I, that absorbs any sunlight filtering down onto the surface from above and turns it into electricity. Previous versions of the cell, by other researchers, were flat.
The new experimental solar cell converts 0.1 per cent of incoming sunlight's energy to electricity. This is still short of the 1.0 per cent conversion rate it needs to be practical — but 10,000 times more than any previous cell of this sort.
Mershin hopes that, in a few years, rural communities would be able to mix waste vegetation — even grass clippings — into a bag containing the zinc and titanium, and paint the mixture onto their roofs to start generating electricity.
"All the major discoveries have now been made," he told SciDev.Net.
"We hope that other groups around the world can now replicate what we've done and optimise the techniques — and that is why we have published our findings in an open-access journal."
Devens Gust, director of the Arizona State University Center for Bio-Inspired Solar Fuel Production in the United States, said: "The advance here is devising a relatively simple method for preparing photovoltaic cells with significant light absorption for laboratory study using this material."
But Frederik Krebs of the Risø National Laboratory for Sustainable Energy in Denmark, who has experience of deploying organic solar cells in Africa, is more cautious.
"There is a very long way from a laboratory vision to a real live application to real live people having no knowledge of [the technology]," he said. He is also concerned that the sun could damage the organic material .
The research was published in Scientific Reports earlier this month (2 February).

 
Design by Free Wordpress Themes | Bloggerized by Lasantha - Premium Blogger Templates