Archive for the ‘Science’ Category

Cull ‘will not halt bat killer’

December 25, 2010 Leave a comment

24 December 2010 Last updated at 09:51 GMT By Mark Kinver Science and environment reporter, BBC News Group of little brown bats displaying symptoms of WNS (Nancy Heaslip/New York Department of Environmental Conservation) A study has warned that if WNS continues unabated, there is a danger that species will be wiped out in less than two decades Culling will not halt the spread of a disease that has killed a million bats in the US since 2006, a study says.

Researchers reached their conclusion by modelling how white-nose syndrome (WNS) is passed from bat to bat.

Writing in Conservation Biology, they add that a cull would not work because the source of the fungal pathogen is believed to occur in the environment.

Earlier studies have warned that WNS could wipe out bat populations in the north-east of the US within 20 years.

Carrying out a cull of bats in areas where the disease is known to be present is one of the options available in an attempt to contain the spread of the killer fungus.

Continue reading the main story Little brown bat displaying symptoms of WNS (Ryan von Linden/New York Department of Environmental Conservation) WNS is associated with a fungus known as Geomyces destructansOnce present in a colony, WNS can wipe out the entire populationIt was first reported in a cave in New York in February 2006The most common visible symptom of an infected bat is a white fungus on the animal’s nose, but it can also appear on its wings, ears or tailOther symptoms include weight loss and abnormal behaviour, such as flying in daylight or sub-zero temperaturesSpecies known to be vulnerable to WNS include: tri-coloured, little brown, big brown, northern long-eared, small-footed and Indiana batsThere is no known risk to human health

(Source: US Fish & Wildlife Service)

“We developed a model taking into account the complexity of the bat life history, looking at the roosts and the areas where there are large contacts between the bats,” said co-author Thomas Hallam from the Department of Ecology and Evolutionary Biology at the University of Tennessee.

“Given the dispersal aspect of the problem and the complexity of hibernating bat ecology, it was a case that these things together certainly meant that culling would not work in the case of bats.”

WNS, described by some as the worst wildlife health crisis in the US in living memory, is named after a white fungus that appears on the muzzle and/or wings of infected animals.

However, bats with WNS do not always have the characteristic visual symptoms, but may display abnormal behaviour around their hibernacula (caves and mines where bats hibernate during winter months).

These behaviours include flying outside during the day (when their insect prey is not available) in sub-zero temperatures, or clustering near the entrance to the hibernaculum.

Professor Hallam explained that there was a high degree of bat-to-bat interaction, which has been identified as the main way the disease is transmitted, during the course of a year.

In autumn, the mating season brings together large numbers of males and females.

This occurs shortly before colonies enter hibernacula, some of which are large enough to house in the region of half-a-million bats.

In the spring, females head to a maternity roost to have their young. Again, this brings bats into contact with members of different colonies.

Since WNS was first recorded in February 2006 in a commercial cave in New York, it has spread to at least 14 states. Cases have also been recorded in a number of Canadian provinces.

Researchers say the fungus associated with the disease, Geomyces destructans, thrives in the dark, damp conditions – such as caves and mines.

Out of control

In their paper, Professor Hallam and co-author Gary McCracken write: “Because the disease is highly virulent, our model results support the hypothesis that transmission occurs in all contact arenas.”

They add: “Our simulations indicated culling will not control WNS in bats primarily because contact rates are high among colonial bats, contact occurs in multiple arenas, and periodic movement between arenas occurs.”

Jeremy Coleman, the national white-nose syndrome co-ordinator for the US Fish and Wildlife Service (FWS), said that culling was a potential tool available to agencies attempting to curb the spread of the disease.

“The spread has been very rapid and very alarming,” he told BBC News.

“The initial comment that spawned all of the ideas of culling was that if we had known what would happen, then we would have gone in and killed every bat and we would not be facing this problem.

“That had a real resonance among researchers and land managers,” Dr Coleman recalled. But he added: “Most people, I would say, feel it is too late for any culling to be effective.”

He explained that the final decision on whether to cull would rest with state or federal agencies.

It is believed that the fungus associated with WNS arrived in the US after it was somehow transported from Europe or possibly Asia.

Map showing the 14 affected states in the US (Image: BBC) To date, 14 states have recorded cases of white-nose syndrome and the fungus

“It was possibly brought over via ‘human-assisted spread’ of some sort – like on somebody’s boots,” Dr Coleman suggested.

“Another possibility is that a bat was somehow transported to North America, perhaps by a cargo plane or freight container, and mixed with bats in New York State.”

A team of European researchers followed up unconfirmed reports in Europe that bats had white fungal growths appearing to match the symptoms of WNS.

In a paper in the Emerging Infectious Diseases journal, they suggested that the Geomyces destructans fungus was present throughout Europe.

However, they added, it seemed as if species of bats in Europe were possibly more immunologically or behaviourally resistant to the fungus than North American species, as it did not increase mortality.

No magic bullet

European bats may be resistant to the disease because they are generally bigger than comparable species in the US. Also, European colonies tend to be not as large as ones found on the other side of the Atlantic.

“What we hope to learn, through genetic means, is the similarities and differences between the North American strains and the European strains,” explained Dr Coleman, who is overseeing the formation of a national management plan that hopes to bring together the efforts of state and federal agencies under one umbrella.

US researchers based at MIT recently sequenced the genome of the US strain of G. destructans and made the data publicly available in a hope that it would “jumpstart work on this problem, to help devise ways to track and combat this fungus”.

“There are a lot of questions where some answers could potentially could give us some hope,” observed Dr Coleman.

Professor Hallam said it was difficult to know if anything could be done to prevent the current outbreak from spreading further and wiping out millions more US bats.

“We have a lot of chemical agents that will get rid of the fungus,” he told BBC News.

“The difficulty is the complexity of bats’ life histories; it is almost impossible to treat enough bats to make it worthwhile.

“I don’t see any easy solution on the horizon.”


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Obama to regulate refinery gases

December 25, 2010 Leave a comment


23 December 2010 Last updated at 18:06 GMT An oil refinery in California Mr Obama is pushing the EPA to cut greenhouse gas emissions after a climate bill failed earlier this year The Obama administration has said it will regulate greenhouse gas emissions from power plants amid opposition from industry and Republicans in Congress.

The Environmental Protection Agency (EPA) said it would regulate emissions from fossil fuel power plants by 2011 and petroleum refineries by 2012.

President Barack Obama is pushing the EPA to cut emissions after a climate bill failed in Congress this year.

But Republican lawmakers have said the EPA’s new rules will harm the economy.

The EPA said it would propose figures for emissions cuts in 2011 and finalise them in 2012.

The new rules are expected to limit the amount of carbon dioxide a plant can emit per each megawatt hour of electricity produced.

“We are following through on our commitment to proceed in a measured and careful way to reduce greenhouse gas pollution that threatens the health and welfare of Americans and contributes to climate change,” EPA chief Lisa Jackson said in a statement.

Collectively, fossil fuel power plants and petroleum refineries release nearly 40% of the total greenhouse gases emitted in the US.

Republican objections

Republicans, who will take control of the House of Representatives when the new Congress convenes on 5 January, have already expressed opposition to the new regulations.

“I think we ought to start with a two-year pause” in upcoming EPA regulations, said Republican Representative Mike Simpson, who is expected to lead a House panel that controls the EPA’s budget.

Mr Obama said last year that the US would curb emissions by 17% by 2020 compared with 2005 levels.

Legislation forcing reductions in carbon dioxide and other greenhouse gas emissions, which are believed by most climate scientists to contribute to global warming, was struck down in Congress this summer.

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Solar plane’s records confirmed

December 25, 2010 Leave a comment

24 December 2010 Last updated at 11:22 GMT Zephyr at launch The 50kg Zephyr is launched by hand The UK-built solar-powered Zephyr aeroplane has been confirmed as a record-breaker following its non-stop two-week flight earlier this year.

The world governing body for air sports records, the Federation Aeronautique Internationale (FAI), gave Zephyr three records including longest time aloft.

Built by defence technology company Qinetiq, the craft completed its two-week flight in the US in July.

The company sees applications in surveillance and communications.

The July feat led to Zephyr being dubbed the “eternal plane”.

“This aircraft can help track pirates off the Horn of Africa, alert the authorities about where and how fast forest fires are spreading, and ensure that soldiers’ communications remain unaffected when fighting in mountainous or hilly terrain,” said Qinetiq’s chief designer Chris Kelleher.

The FAI noted that Zephyr smashed the previous record for the absolute duration of an unmanned autonomous vehicle (UAV) flight – set by Northrop Grumman’s Global Hawk in 2001 – by a factor of 11.

The organisation set the official duration at 336 hours, 22 minutes and eight seconds.

Zephyr’s flight also set a new mark for flight duration for a UAV of its class – unmanned craft weighing 50-500kg – and, for that class, the altitude record of 21,562m (70,741ft).

Wing-to-tail guide to a prototype of the ‘eternal’ plane

Launched by hand, the aircraft flies during daytime on electricity generated by photovoltaic arrays – solar panels – on its wings.

Made of amorphous silicon, the arrays are about as thick as a sheet of paper. They also charge lithium-sulphur batteries that power the craft by night.

During the flight in July, engineers found that Zephyr lost some altitude during the night as power to the engines reduced – but the batteries stored enough to keep the craft aloft.

Key to its success is the ultra-light design, based on carbon fibre, which means that with a wingspan of 22.5m (74ft) it weighs little more than 50kg (110 lb).

Solar-powered high-altitude long-endurance (Hale) UAVs are expected to have a wide range of applications.

The military will want to use them as reconnaissance and communications platforms. Civilian and scientific programmes will equip them with small payloads for Earth observation duties.

Their unique selling point is their persistence over a location. Low-Earth orbiting satellites come and go in a swift pass overhead, and the bigger drones now operated by the military still need to return to base at regular intervals for refuelling.


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New solar fuel machine unveiled

December 24, 2010 Leave a comment

23 December 2010 Last updated at 19:11 GMT By Neil Bowdler Science reporter, BBC News In the prototype, sunlight heats a ceria cylinder which breaks down water or carbon dioxide In the prototype, sunlight heats a ceria cylinder which breaks down water or carbon dioxide A prototype solar device has been unveiled which mimics plant life, turning the Sun’s energy into fuel.

The machine uses the Sun’s rays and a metal oxide called ceria to break down carbon dioxide or water into fuels which can be stored and transported.

Conventional photovoltaic panels must use the electricity they generate in situ, and cannot deliver power at night.

Details are published in the journal Science.

The prototype, which was devised by researchers in the US and Switzerland, uses a quartz window and cavity to concentrate sunlight into a cylinder lined with cerium oxide, also known as ceria.

Ceria has a natural propensity to exhale oxygen as it heats up and inhale it as it cools down.

If as in the prototype, carbon dioxide and/or water are pumped into the vessel, the ceria will rapidly strip the oxygen from them as it cools, creating hydrogen and/or carbon monoxide.

Hydrogen produced could be used to fuel hydrogen fuel cells in cars, for example, while a combination of hydrogen and carbon monoxide can be used to create “syngas” for fuel.

It is this harnessing of ceria’s properties in the solar reactor which represents the major breakthrough, say the inventors of the device. They also say the metal is readily available, being the most abundant of the “rare-earth” metals.

Methane can be produced using the same machine, they say.

Refinements needed

The prototype is grossly inefficient, the fuel created harnessing only between 0.7% and 0.8% of the solar energy taken into the vessel.

Most of the energy is lost through heat loss through the reactor’s wall or through the re-radiation of sunlight back through the device’s aperture.

But the researchers are confident that efficiency rates of up to 19% can be achieved through better insulation and smaller apertures. Such efficiency rates, they say, could make for a viable commercial device.

“The chemistry of the material is really well suited to this process,” says Professor Sossina Haile of the California Institute of Technology (Caltech). “This is the first demonstration of doing the full shebang, running it under (light) photons in a reactor.”

She says the reactor could be used to create transportation fuels or be adopted in large-scale energy plants, where solar-sourced power could be available throughout the day and night.

However, she admits the fate of this and other devices in development is tied to whether states adopt a low-carbon policy.

“It’s very much tied to policy. If we had a carbon policy, something like this would move forward a lot more quickly,” she told the BBC.

It has been suggested that the device mimics plants, which also use carbon dioxide, water and sunlight to create energy as part of the process of photosynthesis. But Professor Haile thinks the analogy is over-simplistic.

“Yes, the reactor takes in sunlight, we take in carbon dioxide and water and we produce a chemical compound, so in the most generic sense there are these similarities, but I think that’s pretty much where the analogy ends.”

The PS10 solar tower plant near Seville, Spain. Mirrors concentrate the sun's power on to a central tower, driving a steam turbine The PS10 solar tower plant near Seville, Spain. Mirrors concentrate the sun’s power on to a central tower, driving a steam turbine

Daniel Davies, chief technology officer at the British photovoltaic company Solar Century, said the research was “very exciting”.

“I guess the question is where you locate it – would you put your solar collector on a roof or would it be better off as a big industrial concern in the Sahara and then shipping the liquid fuel?” he said.

Solar technology is moving forward apace but the overriding challenges remain ones of efficiency, economy and storage.

New-generation “solar tower” plants have been built in Spain and the United States which use an array of mirrors to concentrate sunlight onto tower-mounted receivers which drive steam turbines.

A new Spanish project will use molten salts to store heat from the Sun for up to 15 hours, so that the plant could potentially operate through the night.


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