#Why some GM CROPS fail to fight pests University of Arizona rightoriginal Studyposted by Daniel Stolte-Arizona on June 18 2013u.
ARIZONA (US)# Some genetically modified crops deter pests for a decade or longer while others fail after a few years.
Since 1996 farmers worldwide have planted more than 1 billion acres (400 million hectares) of genetically modified corn and cotton that produce insecticidal proteins from the bacterium Bacillus thuringiensis or Bt for short.
Bt proteins used for decades in sprays by organic farmers kill some devastating pests but are considered environmentally friendly and harmless to people.
However some scientists feared that widespread use of these proteins in genetically modified crops would spur rapid evolution of resistance in pests.
Experts have taken stock to address this concern and to figure out why pests became resistant quickly in some cases but not others.
Bruce Tabashnik and Yves Carri##re in the entomology department at the University of Arizona s College of Agriculture and Life sciences together with visiting scholar Thierry Br##vault from the Center
for Agricultural research for Development or CIRAD in France scrutinized the available field and laboratory data to test predictions about resistance.
Their results are published in the journal Nature Biotechnology. One billion acres#When Bt crops were introduced first the main question was how quickly would pests adapt
and evolve resistance#says Tabashnik who led the study.##And no one really knew; we were just guessing.##
##Now with 1 billion acres of these crops planted over the past 16 years and with the data accumulated over that period we have a better scientific understanding of how fast the insects evolve resistance and why.#
#Analyzing data from 77 studies of 13 pest species in eight countries on five continents the researchers found well-documented cases of field-evolved resistance to Bt crops in five major pests
as of 2010 compared with only one such case in 2005. Three of the five cases are in the United states where farmers have planted about half of the world s Bt crop acreage.
Their report indicates that in the worst cases resistance evolved in two to three years
but in the best cases effectiveness of Bt crops has been sustained more than 15 years. According to the paper both the best and worst outcomes correspond with predictions from evolutionary principles.#
#The factors we found to favor sustained efficacy of Bt crops are in line with what we would expect based on evolutionary theory#says Carri##re explaining that conditions are most favorable
#Computer models showed that refuges should be especially good for delaying resistance when inheritance of resistance in the pest is recessive#explains Carri##re.
Pink bollwormplanting refuges near Bt crops reduces the chances that two resistant insects will mate with each other making it more likely they will breed with a susceptible mate yielding offspring that are killed by the Bt crop.
#Same pest same crop same Bt protein but very different outcomes.##He explained that in the Southwestern US scientists from the EPA academia industry
One of the paper s main conclusions is that evaluating two factors can help to gauge the risk of resistance before Bt crops are commercialized.#
#If the data indicate that the pest s resistance is likely to be recessive and resistance is rare initially the risk of rapid resistance evolution is low#Tabashnik says.
or this pest will probably evolve resistance quickly to this Bt crop.##Prevent resistance? Although the new report is the most comprehensive evaluation of pest resistance to Bt crops so far Tabashnik emphasizes that it represents only the beginning of using systematic data analyses to enhance understanding and management of resistance.#
#These plants have been remarkably useful and in most cases resistance has evolved slower than expected#Tabashnik says.#
#I see these crops as an increasingly important part of the future of agriculture. The progress made provides motivation to collect more data
and to incorporate it in planning future crop deployments.##We ve also started exchanging ideas and information with scientists facing related challenges such as herbicide resistance in weeds and resistance to drugs in bacteria HIV and cancer.#
#But will farmers ever be able to prevent resistance altogether? Tabashnik says he doesn t think so.#
#You re always expecting the pest to adapt. It s almost a given that preventing the evolution of resistance is not possible.#
#Source: University of Arizonayou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license i
#Nasty parasites turn up in dead otters CARDIFF U. UK) A variety of disease-causing parasites are turning up in the bodies of dead otters in the UK.
The most insidious of the parasites, Toxoplasma gondiihich is spread by cat fecesas found in 39.5 percent of otters.
The infection is prevalent across many areas of the UK, with significantly more cases arising in the eastern region.
In humans the parasite can lead to miscarriage and retinal abnormalities. Parasitic flatwormsivided into two species Pseudamphistomum truncatum and Metorchis albidusere found in 18.3 percent of otters.
both are associated with pathological damage to the otter gall bladder. Dissections of affected otters revealed gall bladders to be inflamed or thickened.
Scientists reason that this is likely due to younger otters tending to spend more time in the holt (an otter den.
this may have implications for vector-borne diseases, which can infect humans and their companion animals. he project research on the parasites that infect otters has revealed previously unknown aspects of their distribution
and ecology, says Elizabeth Chadwick, of the Otter Project at Cardiff University. ontinued work is necessary to help us to better understand their transmission pathways
and the impacts that they have on otters, other wildlife, and human health. a
##Quilted graphene is also super strong COLUMBIA U. US) Graphene, even if stitched together from many small crystalline grains,
Graphene consists of a single atomic layer of carbon, arranged in a honeycomb lattice. ur first Science paper,
professor of mechanical engineering at Columbia University, who led the study with Jeffrey Kysar, professor of mechanical engineering. ut defect-free,
or mechanical peeling, from a crystal of graphite. But exfoliation is a time-consuming process that will never be practical for any of the many potential applications of graphene that require industrial mass production. httpv://www. youtube. com/watch?
v=VSPWRC6RCVY Why so weak? Currently, scientists can grow sheets of graphene as large as a television screen by using chemical vapor deposition (CVD), in
which single layers of graphene are grown on copper substrates in a high-temperature furnace. One of the first applications of graphene may be as a conducting layer in flexible displays. ut CVD graphene is titchedtogether from many small crystalline grainsike a quiltt grain boundaries that contain defects in the atomic structure,
Kysar explains. hese grain boundaries can severely limit the strength of large-area graphene if they break much more easily than the perfect crystal lattice,
is about 90 percent as strong as the ideal crystal. his is an exciting result for the future of graphene,
or more in size, says Hone. his strength will be invaluable as scientists continue to develop new flexible electronics and ultrastrong composite materials.
Strong, large-area graphene can be used for a wide variety of applications such as flexible electronics and strengthening componentsotentially,
a television screen that rolls up like a poster or ultrastrong composites that could replace carbon fiber.
Or, the researchers speculate, a science fiction idea of a space elevator that could connect an orbiting satellite to Earth by a long cord that might consist of sheets of CVD graphene,
since graphene (and its cousin material, carbon nanotubes) is the only material with the high strength-to-weight ratio required for this kind of hypothetical application.
The team is excited also about studying 2d materials like graphene. ery little is known about the effects of grain boundaries in 2d materials
The Air force Office of Scientific research and the National Science Foundation supported the research c
#Plankton fossils found in 3 billion-year-old rocks Researchers say they ve discovered microfossils of plankton in 3 billion-year-old rocks.
It is surprising to have large potentially complex fossils that far back says Christopher H. House professor of geosciences at Penn State
The embedded fossils are likely planktonic autotrophs free-floating tiny ocean organisms that produce energy from their environment.
The researchers looked at marine sediment rocks from the Farrel Quartzite in Western australia. Isotopic analysis using secondary ion mass spectrometry was carried out at UCLA. To determine
if these inclusions were actually biological in origin the researchers looked at 15 different samples of Farrel Quartzite
When considered along with published morphological and chemical studies these results indicate that the Farrel Quartzite microstructures are bona fide microfossils
Stable carbon isotope analysis can determine the biological origin of these microfossils because they used carbon dioxide to create energy
and incorporated the carbon into themselves. During this process the organisms selectively incorporate more carbon 12 than carbon 13 from the available carbon producing a signature of biological origin.
Dorothy Oehler who is also a co-author and research scientist Astromaterials Research and Exploration Science Directorate NASA/Johnson Space center notes that the spindles appear to be the same as those found in rocks from the Strelly Pool Formation in Western australia
Researchers from Nagoya University Japan collaborated on the project. The NASA Astrobiology Institute the Astromaterials Research and Exploration Science Directorate Johnson Space center and the Japan Society for the Promotion of Science supported this research.
Source: Penn Stateyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license e
New york University rightoriginal Studyposted by Kathleen Hamilton-NYU on June 7 2013nyu (US)# Robotic fish could reduce the number of live animals needed to study the effects of alcohol on behavior
The two ethanol-exposed groups deviated significantly from this pattern spending more time in other regions of the tank.
#One of the major advantages of robotics is that we can provide a fully controllable consistent stimulus for the zebrafish#says Maurizio Porfiri associate professor of mechanical and aerospace engineering at the Polytechnic institute of New york University (NYU-Poly.#
#This aspect holds promise to reduce the number of live animals used in preclinical research.#
#Relatively little data exist to indicate how #or if#alcohol affects the cognitive abilities of zebrafish.
The National Science Foundation and the Honors Center of Italian Universities supported the project. Source:
#For better concrete, do did as Romans University of California Berkeley rightoriginal Studyposted by Sarah Yang-Berkeley on June 5 2013uc BERKELEY (US)# Ancient Roman structures that have withstood the elements for more than 2000 years
The discovery could help improve the durability of modern concrete which within 50 years often shows signs of degradation particularly in ocean environments.
The manufacturing of Roman concrete also leaves a smaller carbon footprint than does its modern counterpart.
The process for creating Portland cement a key ingredient in modern concrete requires fossil fuels to burn calcium carbonate (limestone) and clays at about 1450 degrees Celsius (2642 degrees Fahrenheit.
That process is responsible for seven percent of global carbon dioxide emissions every year. The production of lime for Roman concrete is much cleaner requiring temperatures that are two-thirds of that required for making Portland cement.#
#Roman concrete has remained coherent and well-consolidated for 2000 years in aggressive maritime environments#says Marie Jackson a research engineer in civil and environmental engineering at University of California Berkeley.#
#It is one of the most durable construction materials on the planet and that was no accident.
#For the study published online in the Journal of the American Ceramic Society Jackson and colleagues characterized samples of Roman concrete taken from a breakwater in Pozzuoli Bay near Naples Italy.#
#Secret ingredient: Volcanic ashconcrete was the Roman empire#s construction material of choice. It was used in monuments such as the Pantheon in Rome as well as in wharves breakwaters and other harbor structures.
Of particular interest to researchers is how Roman#s underwater concrete endured the unforgiving saltwater environment.
The recipe for Roman concrete was described around 30 BC by Marcus Vitruvius Pollio an engineer for Octavian who became Emperor Augustus. The not-so-secret ingredient is volcanic ash
which Romans combined with lime to form mortar. They packed this mortar and rock chunks into wooden molds immersed in seawater.
Rather than battle the marine elements Romans harnessed saltwater and made it an integral part of the concrete.
Also key was a very rare hydrothermal mineral called aluminum tobermorite (Al-tobermorite) that formed in the concrete.#
#Our study provided the first experimental determination of the mechanical properties of the mineral#Jackson says.
Use of Roman concrete decreased because#as the Roman empire declined and shipping declined the need for the seawater concrete declined#Jackson says.#
#Earth-friendly alternativewhile Roman concrete is durable it#s unlikely to replace modern concrete because it is not ideal for construction where faster hardening is needed.
But the researchers are now finding ways to apply their discoveries about Roman concrete to the development of more earth-friendly and durable modern concrete.
whether volcanic ash would be a good large-volume substitute in countries without easy access to fly ash an industrial waste product from the burning of coal that is commonly used to produce modern green concrete.#
#There is not enough fly ash in this world to replace half of the Portland cement being used#says Paulo Monteiro professor of civil and environmental engineering.#
#Many countries don t have fly ash so the idea is to find alternative local materials that will work including the kind of volcanic ash that Romans used.
#The research began with initial funding from King Abdullah University of Science and Technology in Saudi arabia (KAUST)
Saudi arabia has#mountains of volcanic ash#that could potentially be used in concrete Monteiro says. The Loeb Classical Library Foundation Harvard university and the Department of energy provided additional funding.
Source: UC Berkeleyyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license a
#Swarms of tiny drones built to spy on hurricanes University of Florida Posted by Cindy Spence-Florida on June 5 2013u.
and through hurricanes to help predict the strength and path of storms. The autonomous craft#some fly and others dart under the waves#can spy on hurricanes at close range without getting blown to bits
while sensors onboard collect and send in real time the data scientists need to predict the intensity and trajectory of storms:
pressure temperature humidity location and time.##Our vehicles don t fight the hurricane; we use the hurricane to take us places#says Kamran Mohseni professor in the department of mechanical and aerospace engineering and the department of electrical and computer engineering at the University of Florida.
The aerial and underwater vehicles just six inches long and about the weight of an ipod Nano can be launched with commands from a laptop hundreds of miles from the eye of a hurricane.
Mohseni and colleagues use mathematical models to predict regions in the atmosphere and ocean that can give the vehicles a free ride toward their destination.
Once in the vicinity they can be powered off to wait for a particular current of wind or water.
When they detect the current they need for navigation they power back on slip into the current then power off again to conserve fuel as the current carries them to a target location.
In essence they can go for a fact-gathering ride on hurricane winds and waters. The devices are a departure from current technology
which uses hurricane reconnaissance aircraft to punch through a storm#s eye wall and release dropsondes sensors that free-fall
and might or might not collect helpful data. Underwater data are even more difficult to collect
although just as important considering that the warm moist air on the ocean surface provides fuel for hurricanes.
The new vehicles which can be launched hundreds at a time also reduce the cost of hurricane reconnaissance.#
#If you want to blast through a hurricane you have to build a bigger airplane#Mohseni says.#(
#The military) asks for a Batman airplane a super-duper aircraft that could do everything.
But what if you lose one of these super-duper airplanes?##We are going the opposite direction.
We don t have anything that is super duper. We have cheap sensors but with a lot of them you can significantly increase the accuracy of your measurements.
You get super duper on an aggregate level.##The prototypes are about $250 each and are too small and lightweight to cause damage
when they hit something a big consideration in hurricane-force winds and waves. A landing strip to test the aerial vehicles isn t necessary Mohseni just tells them to crash picks them up
and flies them again. The carbon fiber shell of the aerial vehicles is wafer-thin but resilient.
With proper funding the vehicles could be tested in a real-world hurricane in two or three years.
In instances where many are lost#as in a hurricane#the data gained outweighs the cost of the lost vehicles Mohseni says.
Production costs would drop if the vehicles were mass-produced. The vehicles also are smart. A cooperative control algorithm allows them to form a network
and learn from the data they take in for example by adjusting their course when needed. This feature makes them useful for applications beyond hurricanes.
Source: University of Floridayou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license n
#Nano web trips up bed bugs Stony Brook University Posted by James Montalto-Stony Brook on May 31 2013stony BROOK (US)# A new non-chemical solution literally stops bed bugs
in their tracks. The web consists of microfibers 50 times thinner than a human hair
which entangle and trap bed bugs and other insects.##Our nanotechnology produces entanglements that are millions of times more dense than woven products such as fabrics
or carpets#says lead researcher Miriam Rafailovich professor of materials science and engineering and co-director in the program of chemical and molecular engineering at Stony Brook University.
Bed bugs (Cimex lectularius) are small flat parasitic insects that feed solely on the blood of people
and animals while they sleep. They are reddish-brown in color wingless range from one millimeter (mm) to seven mm (roughly the size of Lincoln#s head on a penny)
and can live several months without a blood meal.##The microfibers trap them by attaching to microstructures on their legs taking away their ability to move
which stops them from feeding and reproducing#Rafailovich says. Successful tests were performed using live bed bugs and termites in Rafailovich#s lab with the assistance of Ying Liu a scientist with the Advanced Energy Research and Technology Center and graduate students Shan He and Linxi Zhang.
The microfibers are safe for humans and pets and unlike chemical treatments insects can#t develop a resistance to it.
The patent-pending technology is being commercialized by Fibertrap a private company that employs nontoxic pest control methods.
Source: Stony Brook Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license
#First boson laser could save power Stanford university University of Michigan rightoriginal Studyposted by Bjorn Carey-Stanford on May 24 2013stanford (US)# Scientists have demonstrated a revolutionary electrically driven polariton laser
and now it s time we think about how to put these lasers into practice#says physicist Na Young Kim a member of the Stanford university team which was led by Yoshihisa Yamamoto professor of electrical engineering and of applied physics.#
Charged particles such as electrons exist in discontinuous energy levels like rungs on a ladder. An electron provided with enough energy can become excited
and#jump up to a higher energy level. Excited electrons can spontaneously fall down to an available lower energy level shooting off the difference in energy as a bit of light called a photon.
The amount of time that passes before an excited electron drops down and releases a photon is usually random.
if an electron in an upper energy level was exposed to a photon with proper energy the electron would instantly fall down
A laser keeps this process going by continually providing energy for electrons to move into higher energy levels.
Some of the photons are allowed to escape from the device to serve a purpose such as reading data off a CD or etching a circuit board.
There is a hard limit to the number of electrons that can inhabit a given energy level at any given time
and conventional lasers waste energy unnecessarily exciting electrons to higher energy levels even when the lower levels are too full to accept the excited electrons
and an unlimited number of them can inhabit any given energy level. Using bosons in lasers has been a scientific goal for decades
and confirmed by scientists at the University of Michigan who published their work in the journal Physical Review Letters.)
The current iteration of the polariton laser requires two to five times less energy than a comparable conventional laser
but could require 100 times less energy in the future.##The outcome would look similar to that of the traditional photon lasers
and holes come together to form excitons in excited energy levels. When a photon hits an exciton it forms a polariton
The entire process is like a solar cell in reverse Kim says.##In a solar cell you use light to form excitons
and separate them into an electron and a hole electrically#she says.##We bring together an electron
#One benefit of the electrically driven polariton laser is it only needs to be attached to a power supply to emit photons allowing it to be integrated easily with existing semiconductor chips in the future.
and requires constant cooling by liquid helium to prevent the excitons inside the gallium arsenide semiconductors from being pulled apart by thermal energy.
The team hopes switching to a material that requires more energy to break apart excitons will allow them to build polariton lasers that work at room temperature an important step toward widespread use.#
#We re hoping we can replace conventional semiconductor lasers with these polariton lasers in the future#Kim says.#
but we aim to bring novel devices built on sound physical understanding for cost-effectiveness and efficient power consumption.#
Researchers conducted the work in collaboration with the National Institute of Informatics in Tokyo Japan and a team from the University of W##rzburg in Germany led by physicist Alfred Forchel.
The National Science Foundation the DARPA QUEST program the Japan Society for the Promotion of Science
and the State of Bavaria supported the research. Source: Stanford Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license s
##Dynamo accounts for Sun s weather cycle University of Chicago University of Leeds rightoriginal Studyposted by Richard Mellor-Leeds on May 23 2013u.
what drives the generation of astrophysical magnetic fields like the Sun s. Scientists have known since the 18th century that the Sun regularly oscillates between periods of high and low solar activity in an 11-year cycle
It has become increasingly important to be able to understand the Sun#s magnetic activity as it is the changes in its magnetic field that are responsible for#space weather#phenomena including solar flares and coronal mass ejections.
The research published in Nature explains how the cyclical nature of these large-scale magnetic fields emerges providing a solution to the mathematical equations governing fluids and electromagnetism for a large astrophysical body.
The mechanism known as a dynamo builds on a solution to a reduced set of equations first proposed in the 1950s
when applied to objects with high electrical conductivity. The mechanism takes into account the#shear#effect of mass movement of the ionised gas known as plasma
which makes up the Sun. More importantly it does so in the extreme parameter regime that is relevant to astrophysical bodies.#
#Previously dynamos for large highly conducting bodies such as the Sun would be overwhelmed by small-scale fluctuations in the magnetic field.
which served to damp these small-scale variations revealing the dominant large-scale pattern#says co-author Steve Tobias professor at the University of Leeds#School of Mathematics.
In addition this mechanism could be used to describe other large spinning astronomical bodies with large-scale magnetic fields such as galaxies.
The dynamo was developed through simulations using the high-performance computing facilities located at the University of Leeds.#The fact that it took 50 years
and huge supercomputers shows how complicated the dynamo process really is#says Professor Fausto Cattaneo of the University of Chicago#s department of astronomy and astrophysics.
At the start of the 20th century it was recognized then that these sunspots were the result of the Sun#s magnetic field.
The Science and Technology Facilities Council (STFC) and the National Science Foundation-sponsored Center for Magnetic Self-organization at the University of Chicago partially funded the research.
University of Leedsyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license N
#Bendy nanosensors detect infrared light University of Pennsylvania rightoriginal Studyposted by Evan Lerner-Pennsylvania on May 22 2013u.
PENN (US)# Engineers have used a pattern of nanoantennas to develop a new way of turning infrared light into mechanical action
Existing infrared detectors use cryogenically cooled semiconductors or thermal detectors known as microbolometers in which changes in electrical resistance can be correlated to temperatures.
#We set out to make an optomechanical thermal infrared detector#says Ertugrul Cubukcu assistant professor at the University of Pennsylvania.#
#Rather than changes in resistance our detector works by connecting mechanical motion to changes in temperature.#
At the core of the device is a nanoscale structure#about a tenth of a millimeter wide
and five times as long#made of a layer of gold bonded to a layer of silicon nitride.
The researchers chose these materials because of their different thermal expansion coefficients a parameter that determines how much a material will expand when heated.
Because metals will naturally convert some energy from infrared light into heat researchers can connect the amount the material expands to the amount of infrared light hitting it.#
since gold has the higher thermal expansion coefficient and will expand more.##To measure this movement the researchers used a fiber interferometer.
A fiber optic cable pointed upward at this system bounces light off the underside of the silicon nitride layer enabling the researchers to determine how far the structure has bent upwards.#
#We can tell how far the bottom layer has moved based on this reflected light#Cubukcu says.##We can even see displacements that are thousands of times smaller than a hydrogen atom.#
#Other researchers have developed optomechanical infrared sensors based on this principle but their sensitivities have been comparatively low.
The new device is an improvement in this regard due to the inclusion of#slot#nanoantennas cavities that are etched into the gold layer at intervals that correspond to wavelengths of mid-infrared light.#
so you don t need any additional material to make these antennas#Cubukcu says.##We take the same exact platform
and by patterning it with these nanoscale antennas the conversion efficiency of the detector improves 10 times.#
#The inclusion of nanoantennas provides the device with an additional advantage: the ability to tailor
#Our antennas can be engineered to absorb at any wavelength.##While only a proof-of-concept at this stage future research will demonstrate the device s capabilities as a low-cost way of analyzing individual proteins and gas molecules.
The National Science Foundation Penn s Materials Research Science and Engineering Center Penn s Nano/Bio Interface Center and the Penn Regional Nanotechnology Facility
University of Pennsylvaniayou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license e
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