In the future, clean alternatives such as harvesting energy from electromagnetic waves may help ease the world's energy shortage
WASHINGTON D.C. - For our modern, technologically-advanced society, in which technology has become the solution to a myriad of challenges, energy is critical not only for growth but also, more importantly, survival. The sun is an abundant and practically infinite source of energy, so researchers around the world are racing to create novel approaches to "harvest" clean energy from the sun or transfer that energy to other sources.
This week in the journal Applied Physics Letters, from AIP Publishing, researchers from the University of Waterloo in Canada report a novel design for electromagnetic energy harvesting based on the "full absorption concept." This involves the use of metamaterials that can be tailored to produce media that neither reflects nor transmits any power - enabling full absorption of incident waves at a specific range of frequencies and polarizations.
The metasurface used for collecting electromagnetic energy is shown. O.Ramahi/U.Waterloo
"The growing demand for electrical energy around the globe is the main factor driving our research," said Thamer Almoneef, a Ph.D. student. "More than 80 percent of our energy today comes from burning fossil fuels, which is both harmful to our environment and unsustainable as well. In our group, we're trying to help solve the energy crisis by improving the efficiency of electromagnetic energy-harvesting systems."
Since the inception of collecting and harvesting electromagnetic energy, classical dipole patch antennas have been used. "Now, our technology introduces 'metasurfaces' that are much better energy collectors than classical antennas," explained Omar M. Ramahi, professor of electrical and computer engineering.
Metasurfaces are formed by etching the surface of a material with an elegant pattern of periodic shapes. The particular dimensions of these patterns and their proximity to each other can be tuned to provide "near-unity" energy absorption. This energy is then channeled to a load through a conducting path that connects the metasurface to a ground plane. The key significance of the researchers' work is that it demonstrates for the first time that it's possible to collect essentially all of the electromagnetic energy that falls onto a surface.
"Conventional antennas can channel electromagnetic energy to a load - but at much lower energy absorption efficiency levels," said Ramahi. "We can also channel the absorbed energy into a load, rather than having the energy dissipate in the material as was done in previous works."
As you can imagine, this work has a broad range of applications. Among the most important is space solar power, an emerging critical technology that can significantly help to address energy shortages. It converts solar rays into microwaves - using conventional photovoltaic solar panels - and then beams the microwave's energy to microwave collector farms at designated locations on Earth. Japan is way out in front of rest of the world in this realm, with plans to begin harvesting solar power from space by 2030.
"Our research enables significantly higher energy absorption than classical antennas," Ramahi said. "This results in a significant reduction of the energy harvesting surface footprint. Real estate is a precious commodity for energy absorption - whether it's wind, hydro, solar or electromagnetic energy."
Other key applications include "wireless power transfer - directly adaptable to power remote devices such as RFID devices and tags or even remote devices in general," Ramahi noted. The technology can also be extended to the infrared and visible spectra. "We've already extended our work into the infrared frequency regime and we hope to report very soon about near-unity absorption in those higher-frequency regimes," added Ramahi.
The article, "Metamaterial electromagnetic energy harvester with near unity efficiency," is authored by Thamer S. Almoneef and Omar M. Ramahi. It will appear in the journal Applied Physics Letters on April 14, 2015 (DOI: 10.1063/1.4916232). After that date it can be accessed at: http://scitation.aip.org/content/aip/journal/apl/106/15/10.1063/1.4916232
The authors of this paper are affiliated with the University of Waterloo.
Chimps That Hunt Offer a New View on Evolution
Study shows females playing an unexpectedly big role in hunting
By JAMES GORMAN APRIL 14, 2015
Studies of hunters and gatherers - and of chimpanzees, which are often used as stand-ins for human ancestors - have cast bigger, faster and more powerful males in the hunter role. Now, a 10-year study of chimpanzees in Senegal shows females playing an unexpectedly big role in hunting and males, surprisingly, letting smaller and weaker hunters keep their prey.
The results do not overturn the idea of dominant male hunters, said Jill D. Pruetz of Iowa State University, who led the study. But they may offer a new frame of reference on hunting, tools and human evolution. “We need to broaden our perspective,” she said.
Among the 30 or so chimps Dr. Pruetz and her colleagues observed, called the Fongoli band, males caught 70 percent of the prey, mostly by chasing and running it down. But these chimps are very unusual in one respect. They are the only apes that regularly hunt other animals with tools - broken tree branches. And females do the majority of that hunting for small primates called bush babies.
Craig Stanford, an anthropologist at the University of Southern California who has written extensively on chimp hunting and human evolution, said the research was “really important” because it solidified the evidence for chimps hunting with tools, which Dr. Pruetz had reported in earlier papers.
It also clearly shows “the females are more involved than in other places,” he said, adding that it provides new evidence to already documented observations that female chimps are “much more avid tool users than males are.”
All chimpanzees eat a variety of plant and animal foods, including insects like termites. And all chimpanzees eat some other animals. The most familiar examples of chimpanzee hunting are bands of the apes chasing red colobus monkeys through the trees in the rain forests of East Africa.
In this kind of pursuit, the largest, strongest, fastest chimps dominate - and those are adult males. When females and smaller chimps do catch an animal, an adult male may simply take it away, although the meat is eventually shared. The theft rate in other groups of chimps is around 25 percent, Dr. Pruetz said. Those other chimps do not hunt with tools.
The Fongoli chimpanzees live in a mix of savanna and woodlands where prey is not as abundant as in rain forests. There are no red colobus monkeys, and although the chimps do hunt young vervet monkeys and baboons, the much smaller bush babies are their main prey.
Dr. Pruetz argues that less food may have prompted both technological and social innovation, resulting in new ways to hunt and new social interactions as well. Humans evolved in a similar environment, and, as she and her colleagues write in Royal Society Open Science, “tool-assisted hunting could have similarly been important for early hominins.”
The tools in question are broken branches that Dr. Pruetz calls jabbing tools. The season for bush baby hunting is June, when the temperature may be well over 100 and the humidity is suffocating. The Fongoli chimps find the bush babies in their dens in trees. Chimps will stab and poke one of the small animals, sometimes wounding but not impaling it, until it comes out of its hiding place. The chimps will grab it, Dr. Pruetz said, and immediately “bite the head off.”
Females, even those with infants, and juvenile chimps can do this kind of hunting. The process does not put a premium on speed and strength as the chase does, so big males do not have an advantage. But there is more than technique and technology involved. There is social change.
By and large, said Dr. Pruetz, the adult males, which could take away a kill, show a “respect of ownership.” Theft rates are only about 5 percent. The chimps she studies also have more mixed-sex social groups than chimp bands in East Africa.
Travis Pickering, an anthropologist at the University of Wisconsin, said that with less food available it seems that the Fongoli chimps, “have to be more inventive” and that “these hunting weapons even the playing field for non-adults and females.”
Early hominins may have been in a similar situation, he said. Hunting among human ancestors “very quickly became a male-dominated activity,” he said, but “female hominins could very well have been the inventors of weapons.”
When it comes to getting food, deciding who does what depends on definitions. Collecting insects, for example, is defined as gathering, not hunting. In the case of the bush babies, however, though they are small, they struggle and flee, and will bite. Any bite, no matter how small, can pose the danger of infection, so the pursuit of bush babies qualifies as hunting, Dr. Pruetz says, and Dr. Stanford and Dr. Pickering agree.
Tags on DNA from fathers' sperm linked to children's autism symptoms
In a small study, Johns Hopkins researchers found that DNA from the sperm of men whose children had early signs of autism shows distinct patterns of regulatory tags that could contribute to the condition. A detailed report of their findings will be published online in the International Journal of Epidemiology on April 15.
Autism spectrum disorder (autism) affects one in 68 children in the U.S. Although studies have identified some culprit genes, most cases remain unexplained. But most experts agree that autism is usually inherited, since the condition tends to run in families. In this study, investigators looked for possible causes for the condition not in genes themselves, but in the "epigenetic tags" that help regulate genes' activity.
"We wondered if we could learn what happens before someone gets autism," says Andrew Feinberg, M.D., M.P.H., the King Fahd Professor of Molecular Medicine and director of the Center for Epigenetics at the Johns Hopkins University School of Medicine. "If epigenetic changes are being passed from fathers to their children, we should be able to detect them in sperm," adds co-lead investigator Daniele Fallin, Ph.D., professor and chair of the Department of Mental Health in the Bloomberg School of Public Health and director of the Wendy Klag Center for Autism and Developmental Disabilities.
In addition to being easier to sample than egg cells from women, sperm are more susceptible to environmental influences that could alter the epigenetic tags on their DNA. Feinberg, Fallin and their team assessed the epigenetic tags on DNA from sperm from 44 dads. The men were part of an ongoing study to assess the factors that influence a child early on, before he or she is diagnosed with autism. The study enrolls pregnant mothers who already have a child with autism and collects information and biological samples from these mothers, the new baby's father and the babies themselves after birth. Early in the pregnancy, a sperm sample was collected from fathers enrolled in the study. One year after the child was born, he or she was assessed for early signs of autism using the Autism Observation Scale for Infants (AOSI).
The researchers collected DNA from each sperm sample and looked for epigenetic tags at 450,000 different positions throughout the genome. They then compared the likelihood of a tag being in a particular site with the AOSI scores of each child. They found 193 different sites where the presence or absence of a tag was statistically related to the AOSI scores.
When they looked at which genes were near the identified sites, they found that many of them were close to genes involved in developmental processes, especially neural development. Of particular interest was that four of the 10 sites most strongly linked to the AOSI scores were located near genes linked to Prader-Willi syndrome, a genetic disorder that shares some behavioral symptoms with autism. Several of the altered epigenetic patterns were also found in the brains of individuals with autism, giving credence to the idea that they might be related to autism.
The team plans to confirm its results in a study of more families and to look at the occupations and environmental exposures of the dads involved. There is currently no genetic or epigenetic test available to assess autism risk.
Other authors of the report include Jason Feinberg, Kelly Bakulski and Shannon Brown of the Johns Hopkins Bloomberg School of Public Health; Rakel Trygvadottir of The Johns Hopkins University; Andrew Jaffe of the Lieber Institute for Brain Development; Lynn Goldman of The George Washington University; Lisa Croen of Kaiser Permanente; Irva Hertz-Picciotto of the University of California, Davis; and Craig Newschaffer of Drexel University.
This work was supported by grants from the National Institute of Environmental Health Sciences (R01 ES017646, R01 ES16443) and Autism Speaks.
Dementia 'halted in mice brains'
Tweaking the brain's immune system with a drug has prevented mice developing dementia, a study shows.
By James Gallagher Health editor, BBC News website
The team at Duke University, in the US, showed immune cells which start attacking nutrients in the brain may be a trigger for the disease. They say their findings could open up new avenues of research for a field that has not developed a single drug to slow the progression of the disease.
Experts said the findings offered new hope of a treatment.
The researchers indentified microglia - normally the first line of defence against infection in the brain - as major players in the development of dementia.
They found some microglia changed to become exceptionally adept at breaking down a component of protein, an amino acid called arginine, in the early stages of the disease. As arginine levels plummeted, the immune cells appeared to dampened the immune system in the brain.
In mouse experiments, a chemical was used to block the enzymes that break down arginine. They showed fewer of the characteristics of dementia such as damaged proteins collecting in the brain and the animals performed better in memory tests.
One of the researchers, Dr Matthew Kan, said: "All of this suggests to us that if you can block this local process of amino acid deprivation, then you can protect the mouse, at least from Alzheimer's disease.
"We see this study opening the doors to thinking about Alzheimer's in a completely different way, to break the stalemate of ideas in Alzheimer's disease."
However, the findings do not suggest that arginine supplements could combat dementia as the boosted levels would still be broken down.
Dr James Pickett, from the Alzheimer's Society said the study was "offering hope that these findings could lead to new treatments for dementia". He added: "This study in animals joins some of the dots in our incomplete understanding of the processes that cause Alzheimer's disease, in particular around the role played by the immune system."
Dr Laura Phipps, from Alzheimer's Research UK, said the study was "interesting" and shed "more light on the mechanisms of immune system involvement in Alzheimer's".
But she cautioned clinical trials in people were still needed and that "the findings do not suggest that supplementation of the amino acid could mirror the benefits seen in these mice".
Archaeologists Take Wrong Turn, Find World’s Oldest Stone Tools
Archaeologists working in the Kenyan Rift Valley have discovered the oldest known stone tools in the world.
By Kate Wong
SAN FRANCISCO – Dated to around 3.3 million years ago, the implements are some 700,000 years older than stone tools from Ethiopia that previously held this distinction. They are so old, in fact, that they predate the earliest fossils representing our genus, Homo, by half a million years. As such they suggest that stone tool manufacture began not with Homo, but with a more primitive member of the human family.
A happy accident led to the discovery of the ancient tools. Sonia Harmand of Stony Brook University and her team had been en route to a known fossil site on the western shore of Lake Turkana one morning in July 2011 when the group took a wrong turn and ended up in a previously unexplored area. The researchers decided to survey it and by teatime they had found stone artifacts. They named the site Lomekwi 3, and went on to recover dozens of tools - including flakes, cores and anvils–from both the surface and below ground. Harmand described the findings April 14 in a talk given at the annual meeting of the Paleoanthropology Society in San Francisco.
“The cores and flakes we recovered are clearly knapped and are not the result of accidental or natural rock fracture,” Harmand said. “The Lomekwi 3 knappers were able to deliver sufficient intentional force to detach repeatedly series of adjacent and superposed flakes and then to continue knapping by rotating the cores.” The team determined the age of the tools based on their stratigraphic position relative to two layers of volcanic ash and a magnetic reversal of known ages.
The tools from Lomekwi 3 are quite large - larger than the stone tools from the site of Gona in Ethiopia that were previously the oldest on record and larger than the rocks that chimpanzees use to crack open nuts. According to Harmand, preliminary observations suggest that the Lomekwi toolmakers intentionally selected big, heavy blocks of very hard raw material from nearby sources even though smaller blocks were available. They used various knapping techniques to remove the sharp-edged flakes from the cores.
Exactly what the Lomekwi knappers used their tools for is not yet clear. Animal bones recovered thus far at the site do not show any signs of human activity. But evidence from another site does suggest that hominins (the group that includes H. sapiens and its extinct relatives) were butchering animals back then. In 2010 scientists working at the site of Dikika in Ethiopia, where fossils belonging to Lucy’s species, Australopithecus afarensis, had previously turned up, announced that they had recovered 3.4 million-year-old animal bones bearing distinctive marks. They argued that hominins had made the marks in the course of slicing meat off the bones with stone tools. The claim sparked heated debate. Some skeptics countered that the alleged cut marks were instead the result of the bones having been trampled by passing animals; others suggested that they were bite marks from crocodiles. The discovery of the Lomekwi tools does not prove that hominins made the Dikika marks, but it shows that near contemporaries of the Dikika hominins made implements capable of leaving behind such marks.
The identity of the Lomekwi knappers is unknown. If stone tool manufacture is the exclusive purview of Homo, then Homo must have evolved far earlier than the fossil record currently indicates. A more plausible scenario, Harmand said, is that Australopithecus or another hominin, Kenyanthropus (found nearby) - both of which are known to have been around 3.3 million years ago–made the Lomekwi tools. Whether Kenyanthropus is in fact a distinct hominin lineage or part of Australopithecus is a matter of debate, however.
Up to this point, the earliest stone tools have been considered part of the so-called Oldowan toolmaking tradition. Louis Leakey coined the term to describe tools found at Olduvai Gorge in the 1930s. But Harmand says the newly discovered tools are different enough from the early Oldowan implements to warrant a new name: the Lomekwian.
Marijuana Plant Extract Reduces Epileptic Seizures by Half
GW Pharmaceuticals Plc’s cannabidiol, made from the non-psychoactive portion of a marijuana plant, cut by half the seizures suffered by epilepsy patients in an expanded access program that didn’t use a placebo.
The experience of 213 hard-to-treat patients age 2 to 42, including some who were already taking a dozen drugs to fend off seizures, is a promising start for the strawberry-flavored liquid extract, which may be a potent new therapy for the condition, said lead researcher Orrin Devinsky, director of the New York University Langone Comprehensive Epilepsy Center.
The findings released Monday are scheduled to be presented at the American Academy of Neurology’s annual meeting on April 22 in Washington.
GW Pharma is seeking regulatory approval for the therapy to treat patients with severe forms of epilepsy and expects to present results from mandated studies by early 2016, said Chief Executive Officer Justin Gover. Epidiolex, as the oil is known, is being compared with a placebo to affirm its safety and effectiveness.
“For this group that has failed multiple medications, the response is quite positive,” Devinsky said. “Over time it’s certainly the hope that this would replace other therapies,” if studies that use comparison groups are successful.
The results were consistent across different types of epilepsy, including Dravet syndrome, a rare and intractable form with few treatment options, and Lennox-Gastaut syndrome, marked by a brief loss of muscle tone that triggers “drop” seizures. Overall, the number of seizures fell by an average of 54 percent for the 137 patients who were on the medication for three months.
GW Pharma’s American depository receipts gained 1.9 percent to $98 in late trading.
GW Pharma has two final-stage trials for each disease already under way.
Side effects included drowsiness, diarrhea and decreased appetite. Six percent of the patients stopped taking the medicine because of side effects or complications.
More than 5 million Americans have been diagnosed with epilepsy, a disorder marked by abnormal electrical activity in the brain.
Symptoms can include convulsions, muscle spasms, loss of consciousness and different types of seizures. While there are numerous drugs approved to treat seizures, up to one -third of patients struggle to control the condition with those medications.
The program was the result of good timing, Devinsky said. GW Pharma was working on marijuana-based products to treat conditions including diabetes and ulcerative colitis when reports began to surface on social media about success families were having by treating their epileptic children with marijuana.
Unproven products were starting to emerge to meet the demand, he said.
Academic researchers were also seeing benefits in early tests involving animals. Devinsky and other investigators approached the company to see if it was interested in studying their compounds for hard-to-treat epileptics. The company agreed, and some patients have already been using the oil for more than a year with good results, he said.
“It was really a community effort by parents, physicians and industry coming together,” Devinsky said.
If approved, Epidiolex would be the first cannabis plant-derived therapeutic accepted by the U.S. Food and Drug Administration and covered by health insurance. It differs from marijuana-based herbal products because it is pure cannabidiol, with no psychoactive molecules, and is made under strict manufacturing methods, Gover said.
GW Pharma already has a cannabis-based medicine approved outside the U.S. called Sativex for spasticity due to multiple sclerosis. It is also being tested for pain due to advanced cancer, Gover said.