Tuesday, September 28, 2010

HOME'S ELECTRICAL WIRING ACTS AS ANTENNA TO RECEIVE LOW-POWER SENSOR DATA

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If these walls had ears, they might tell a homeowner some interesting things. Like when water is dripping into an attic crawl space, or where an open window is letting hot air escape during winter.

The walls do have ears, thanks to a device that uses a home's electrical wiring as a giant antenna. Sensors developed by researchers at the University of Washington and the Georgia Institute of Technology use residential wiring to transmit information to and from almost anywhere in the home, allowing for wireless sensors that run for decades on a single watch battery. The technology, which could be used in home automation or medical monitoring, will be presented this month at the Ubiquitous Computing conference in Copenhagen, Denmark.

Low-cost sensors recording a building's temperature, humidity, light level or air quality are central to the concept of a smart, energy-efficient home that automatically adapts to its surroundings. But that concept has yet to become a reality.

"When you look at home sensing, and home automation in general, it hasn't really taken off," said principal investigator Shwetak Patel, a UW assistant professor of computer science and of electrical engineering. "Existing technology is still power hungry, and not as easy to deploy as you would want it to be."

That's largely because today's wireless devices either transmit a signal only several feet, Patel said, or consume so much energy they need frequent battery replacements.

"Here, we can imagine this having an out-of-the-box experience where the device already has a battery in it, and it's ready to go and run for many years," Patel said. Users could easily sprinkle dozens of sensors throughout the home, even behind walls or in hard-to-reach places like attics or crawl spaces.

Patel's team has devised a way to use copper electrical wiring as a giant antenna to receive wireless signals at a set frequency. A low-power sensor placed within 10 to 15 feet of electrical wiring can use the antenna to send data to a single base station plugged in anywhere in the home.

The device is called Sensor Nodes Utilizing Powerline Infrastructure, or SNUPI. It originated when Patel and co-author Erich Stuntebeck were doctoral students at Georgia Tech and worked with thesis adviser Gregory Abowd to develop a method using electrical wiring to receive wireless signals in a home. They discovered that home wiring is a remarkably efficient antenna at 27 megahertz. Since then, Patel's team at the UW has built the actual sensors and refined this method. Other co-authors are UW's Gabe Cohn, Jagdish Pandey and Brian Otis.

Cohn, a UW doctoral student in electrical engineering, was lead student researcher and tested the system. In a 3,000-square-foot house he tried five locations in each room and found that only 5 percent of the house was out of the system's range, compared to 23 percent when using over-the-air communication at the same power level. Cohn also discovered some surprising twists -- that the sensors can transmit near bathtubs because the electrical grounding wire is typically tied to the copper plumbing pipes, that a lamp cord plugged into an outlet acts as part of the antenna, and that outdoor wiring can extend the sensors' range outside the home.

While traditional wireless systems have trouble sending signals through walls, this system actually does better around walls that contain electrical wiring.

Most significantly, SNUPI uses less than 1 percent of the power for data transmission compared to the next most efficient model.

"Existing nodes consumed the vast majority of their power, more than 90 percent, in wireless communication," Cohn said. "We've flipped that. Most of our power is consumed in the computation, because we made the power for wireless communication almost negligible."

The existing prototype uses UW-built custom electronics and consumes less than 1 milliwatt of power when transmitting, with less than 10 percent of that devoted to communication. Depending on the attached sensor, the device could run continuously for 50 years, much longer than the decade-long shelf life of its battery.

"Basically, the battery will start to decompose before it runs out of power," Patel said.

Longer-term applications might consider using more costly medical-grade batteries, which have a longer shelf life. The team is also looking to reduce the power consumption even further so no battery would be needed. They say they're already near the point where solar energy or body motion could provide enough energy.

The researchers are commercializing the base technology, which they believe could be used as a platform for a variety of sensing systems.

Another potential application is in health care. Medical monitoring needs a compact device that can sense pulse, blood pressure or other properties and beam the information back to a central database, without requiring patients to replace the batteries.

The technology does not interfere with electricity flow or with other emerging systems that use electrical wiring to transmit Ethernet signals between devices plugged into two outlets.

University of Washington

LINK TO AUTISM IN BOYS FOUND IN MISSING DNA

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New research from the Centre for Addiction and Mental Health (CAMH) and The Hospital for Sick Children (SickKids), both in Toronto, Canada provides further clues as to why Autism Spectrum Disorder (ASD) affects four times more males than females. The scientists discovered that males who carry specific alterations of DNA on the sole X-chromosome they carry are at high risk of developing ASD. The research is published in the September 15 issue of Science Translational Medicine.

ASD is a neurological disorder that affects brain functioning, resulting in challenges with communication and social interaction, unusual patterns of behaviour, and often, intellectual deficits. ASD affects one in every 120 children and a startling one in 70 boys. Though all of the causes of ASD are not yet known, research has increasingly pointed towards genetic factors. In recent years, several genes involved in ASD have successfully been identified.

The research team was led by Dr. John B. Vincent, Senior Scientist and head of CAMH's Molecular Neuropsychiatry and Development Laboratory and Dr. Stephen Scherer, Senior Scientist and Director of The Centre for Applied Genomics at SickKids, and Director of the McLaughlin Centre at the University of Toronto. The scientists analyzed the gene sequences of 2,000 individuals with ASD, along with others with an intellectual disability, and compared the results to thousands of population controls. They found that about one per cent of boys with ASD had mutations in the PTCHD1 gene on the X-chromosome. Similar mutations were not found in thousands of male controls. Also, sisters carrying the same mutation are seemingly unaffected.

"We believe that the PTCHD1 gene has a role in a neurobiological pathway that delivers information to cells during brain development – this specific mutation may disrupt crucial developmental processes, contributing to the onset of autism." said Dr. Vincent. "Our discovery will facilitate early detection, which will, in turn, increase the likelihood of successful interventions."

"The male gender bias in autism has intrigued us for years and now we have an indicator that starts to explain why this may be," says Dr. Scherer. "Boys are boys because they inherit one X-chromosome from their mother and one Y-chromosome from their father. If a boy's X-chromosome is missing the PTCHD1 gene or other nearby DNA sequences, they will be at high risk of developing ASD or intellectual disability. Girls are different in that, even if they are missing one PTCHD1 gene, by nature they always carry a second X-chromosome, shielding them from ASD." Scherer adds, "While these women are protected, autism could appear in future generations of boys in their families."

Researchers hope further investigation into the PTCHD1 gene will also indicate potential avenues for new therapy.

(Photo: CAMH)

CAMH

TOWARD RESOLVING DARWIN'S 'ABOMINABLE MYSTERY'

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What, in nature, drives the incredible diversity of flowers? This question has sparked debate since Darwin described flower diversification as an 'abominable mystery.' The answer has become a lot clearer, according to scientists at the University of Calgary whose research on the subject is published today in the on-line edition of the journal Ecology Letters.

Drs. Jana Vamosi and Steven Vamosi of the Department of Biological Sciences have found through extensive statistical analysis that the size of the geographical area is the most important factor when it comes to biodiversity of a particular flowering plant family.

The researchers were looking at the underlying forces at work spurring diversity -- such as why there could be 22,000 varieties of some families of flowers, orchids for example, while there could be only forty species of others, like the buffaloberry family. In other words, what factors have produced today's biodiversity?

"Our research found that the most important factor is available area. The number of species in a lineage is most keenly determined by the size of the continent (or continents) that it occupies," says Jana Vamosi.

Steven Vamosi adds that while the findings of this research mostly shed light on what produces the world's diversity, it may comment on what produces extinction patterns as well.

"The next step is to determine if patterns of extinction risk mirror those observed for diversification, specifically to contrast the relative influence of available area and traits," he says.

Typically, when it comes to explaining the biodiversity of flowering plants, biologists' opinions fall into three different camps: family traits (for example a showy flower versus a plain flower), environment (tropic versus arid climate) or sheer luck in geography (a seed makes it way to a new continent and expands the geographical range of a family).

But the Vamosi research demonstrates that geography isn't the only answer, traits of the family came in a close second to geography. Traits that may encourage greater diversity are known as "key innovations" and scientists have hypothesized that some families possess more species because they are herbs, possess fleshy fruits (such as an apple or peach), or that their flowers have a more complex morphology. Zygomorphy (or when a flower can only be divided down the middle to make two equal mirror images) is thought to restrict the types of pollinators that can take nectar and pollen from the flower. Flies, for instance, won't often visit zygomorphic flowers. Bees, on the other hand, adore them.

"Although geography may play a primary role, a close second is the flower morphology of the plants in a particular family," says Jana Vamosi. "So essentially all camps may claim partial victory because morphological traits should be considered in the context of geographical area."

(Photo: Riley Brandt)

University of Calgary

CARBON NANOTUBES TWICE AS STRONG AS ONCE THOUGHT

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Carbon nanotubes — those tiny particles poised to revolutionize electronics, medicine, and other areas — are much bigger in the strength department than anyone ever thought, scientists are reporting. New studies on the strength of these submicroscopic cylinders of carbon indicate that on an ounce-for-ounce basis they are at least 117 times stronger than steel and 30 times stronger than Kevlar, the material used in bulletproof vests and other products. The findings, which could expand commercial and industrial applications of nanotube materials, appear in the monthly journal ACS Nano.

Stephen Cronin and colleagues point out that nanotubes — barely 1/50,000th the width of a human hair — have been renowned for exceptional strength, high electrical conductivity, and other properties. Nanotubes can stretch considerably like toffee before breaking. This makes them ideal for a variety of futuristic applications, even, if science fiction ever become reality, as cables in "space elevators" that lift objects from the Earth's surface into orbit.

To resolve uncertainties about the actual strength of nanotubes, the scientists applied immense tension to individual carbon nanotubes of different lengths and widths. They found that nanotubes could be stretched up to 14 percent of their normal length without breaking, or more than twice that of previous reports by others. The finding establishes "a new lower limit for the ultimate strength of carbon nanotubes," the article noted.

ACS

UNDERSTANDING BEHAVIORAL PATTERNS: WHY BIRD FLOCKS MOVE IN UNISON

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Animal flocks, be it honeybees, fish, ants or birds, often move in surprising synchronicity and seemingly make unanimous decisions at a moment's notice, a phenomenon which has remained puzzling to many researchers.

New research published in New Journal of Physics (co-owned by the Institute of Physics and German Physical Society), uses a particle model to explain the collective decision making process of flocks of birds landing on foraging flights.

Using a simple self-propelled particle (SPP) system, which sees the birds represented by particles with such parameters as position and velocity, the researchers from Budapest, Hungary, find that the collective switching from the flying to the landing state overrides the individual landing intentions of each bird.

In the absence of a decision making leader, the collective shift to land is heavily influenced by perturbations the individual birds are subject to, such as the birds' flying position within the flock. This can be compared to an avalanche of piled up sand, which would occur even for perfectly symmetric and cautiously placed grains, but in reality happens much sooner because of increasing, non-linear fluctuations.

As the researchers explain, "Our main motivation was to better understand something which is puzzling and out there in nature, especially in cases involving the stopping or starting of a collective behavioural pattern in a group of people or animals.

"We propose a simple model for a system whose members have the tendency to follow the others both in space and in their state of mind concerning a decision about stopping an activity. This is a very general model, which can be applied to similar situations."

Possible applications include collectively flying, unmanned aerial vehicles, initiating a desired motion pattern in crowds or groups of animals and even finance, where the results could be used to interpret collective effects on selling or buying shares on the stock market.

(Photo: IoP)

IoP

LEARNING TO LIVE ON LAND: HOW SOME EARLY PLANTS OVERCAME AN EVOLUTIONARY HURDLE

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The diversity of life that can be seen in environments ranging from the rainforests of the Amazon to the spring blooms of the Mohave Desert is awe-inspiring. But this diversity would not be possible if the ancestors of modern plants had just stayed in the water with their green algal cousins. Moving onto dry land required major lifestyle changes to adapt to this new "hostile" environment, and in turn helped change global climate and atmospheric conditions to conditions we recognize today. By absorbing carbon while making food, and releasing oxygen, early plants shaped ecosystems into a more hospitable environment, paving the way for animals to make a parallel journey onto land.

New research by Dr. Linda Graham and colleagues at the University of Wisconsin, Madison focuses on this transition and adaptive changes in the uptake of carbon-based compounds, such as sugars. This work, which is published in the September issue of the American Journal of Botany, suggests a basis for incorporating evolutionary/paleontological information into global carbon cycling models.

All plants descended from a group of ancestral green algae, whose modern representatives thrive in aqueous environments. The simplest of modern land plants—several groups of bryophytes—are the closest living relatives to the first plants to colonize land. By comparing green algae and bryophytes, Graham and her co-researchers obtained insight into the evolutionary hurdles that plants needed to overcome to transition successfully to life on land, and how early plants' success influenced carbon cycling.

The researchers quantified and compared growth responses to exogenously (externally) supplied sugars in two green algae, Cylindrocystis brebissoni and Mougeotia sp., and one peat moss species, Sphagnum compactum. They found that sugar/carbon uptake in peat moss was not restricted to the products of photosynthesis. Rather, addition of sugars to the growth media increased biomass by almost 40-fold. This ability to utilize sugars not only from photosynthesis but also from the environment is called mixotrophy, not previously thought to play a significant role in the growth of mosses. The two green algae also responded to external sugar, though less so than the peat moss.

Peat mosses "store a large percentage of global soil carbon, thereby helping to stabilize Earth's atmospheric chemistry and climate," stated Graham.

This has far-ranging implications to global carbon cycling because previous work examining the response of mosses to carbon availability assumed that carbon dioxide was the only carbon source available to peat mosses and ancestral plants. The new results indicate that efforts to model global atmospheric and climate changes, both in the present and millions of years ago during the colonization of land, should take mixotrophic behavior of early diverging plants into account.

Graham and her co-researchers have enjoyed a cross-hemispheric partnership, from Wisconsin north to Canada and south to Chile, and look forward to comparing the biology of Northern and Southern hemisphere peat mosses. In particular, they would like to "explore in more depth the role of sugars in the establishment of ecologically important microbial symbioses, particularly nitrogen-fixing cyanobacteria living with peat mosses," explained Graham.

(Photo: Lee Wilcox, University of Wisconsin, Madison, Wisconsin)

American Journal of Botany

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