US approves HIV-prevention drug Truvada

US health regulators have for the first time approved a drug to prevent HIV infection. Truvada can be used by those at high risk of infection and anyone having HIV-infected partners. Studies showed the drug reduced the risk of contracting HIV by up to 73%.

Some health workers and groups active in the HIV community opposed a green light for the once-daily pill. There have been concerns the circulation of such a drug could engender a false sense of security and mean people will take more risks. There have also been fears that a drug-resistant strain of HIV could develop.

In a statement, the FDA stressed that the drug should be used as part of a "comprehensive HIV prevention plan", including other methods and regular HIV testing. In May, an advisory group of health experts recommended approval for the pill.

Truvada, made by California-based Gilead Sciences, is already backed by the FDA to be taken with existing antiretroviral drugs for people who have HIV. Studies from 2010 showed that Truvada reduced the risk of HIV in healthy gay men - and among HIV-negative heterosexual partners of HIV-positive people - by between 44% and 73%.

Michael Barton of UNAIDS, the Joint United Nations Programme on HIV/AIDS, said there was good trial evidence that the drug could significantly cut the risk of the infection being passed on, but only if the tablets are taken consistently.

Many of the men in the trials did not take the drug regularly enough to get the full protection. He said that, in most circumstances, it would be better to treat the HIV-positive partner in the couple rather than focus on the HIV-negative one. "We know that for HIV-positive people if they consistently take antiretroviral drugs and their viral load is suppressed for them it's almost impossible to transmit the virus."

Antiretroviral drugs will also prolong their life. But he said the new drug might be useful in situations where, for example, a woman has a partner with HIV who is unwilling to take antiretrovirals or use other methods. Truvada is approved in the UK for the treatment of HIV, but not prevention.

Types of HIV drug treatment

Antiretroviral therapy - used to treat the infection, reduce the chance of onward transmission and prolong life

Post-exposure prophylaxis (PEP) - emergency treatment (within 72 hours of exposure) aimed at preventing infection shortly after exposure

Pre-exposure prophylaxis (PrEP) - medication taken to reduce or eliminate the chance of getting infected

Light trick to see around corners

Scientists have found a novel way to get images through "scattering" materials such as frosted glass or skin, and even to "see around corners". Much research in recent years has focused on correcting for scattering, mostly for medical applications.

But the new trick is quick, simple and uses natural light rather than lasers. It uses what is called a spatial light modulator to "undo" the scattering that makes objects opaque or non-reflecting. 

A camera that can "see around corners" garnered much attention in 2010, using a series of timed laser pulses to illuminate a scene and working out what is around a corner from the timing of the reflections. The prototype device was just one of a great many research efforts trying to crack the problem of scattering. But for some applications, the "time-of-flight" approach that the laser-based camera uses is not sufficient.

"If you want to look to see an embryo developing inside an egg but the eggshell scatters everything, or you want to look through the skin, scattering is the main enemy there, and time-of-flight is not a good solution," explained senior author of the study Yaron Silberberg Weizmann Institute of Science in Israel. For those kinds of problems, Prof Silberberg and colleagues at the Weizmann Institute of Science in Israel have pushed the limits of what spatial light modulators (SLMs) can do.

SLMs modify what is known as the phase of an incoming light beam. Like a series of waves on the ocean that run over rocks or surfers, the waves in light can be slowed down or redirected when they hit scattering materials.

SLMs are made up of an array of pixels that can correct for this by selectively slowing down some parts of the beam and allowing others to pass untouched - when an electric field is applied to a pixel, it changes the speed at which light passes through it.

Prof Silberberg and his team first set up their SLM by shining light from a normal lamp through a highly scattering plastic film and allowing a computer to finely tune the SLM until they could see a clear image of the lamp through the film. Keeping the SLM set this way, they were then able to obtain clear images of other objects through the film - the SLM effectively turns the film back into a clear sheet.

"What we have shown is that you don't need lasers - everybody else was doing this with lasers, and we showed you can do it with incoherent light from a lamp or the Sun - natural light," Prof Silberberg said. But the team then realised that the same approach can work in reflection - that is, not passing through a scattering material but bouncing off of it, such as the case of light bouncing off a wall at a corner.

They then showed the procedure works just as well when the light from an object bounces off a piece of paper; the SLM could "learn" how to undo the paper's scattering effect, making it a nearly perfect reflector. As Prof Silberberg puts it: "You can take a piece of wall and effectively turn it into a mirror, and this is the part that makes everybody raise an eyebrow."

However, he said that the primary use for the technique will be in biological and medical studies - especially tackling the highly scattering white brain matter in neurological imaging - rather than the business of seeing through thin materials or around corners.

"I don't want to say that it solves the problems of secret organisations and Peeping Toms and so on, that's not going to be so simple. But the principle is there. We have not started to tackle these things... but I see how much interest this raises and think maybe we should."

Invisible electric material

Researchers at the University of Exeter in the UK say they have created a super-thin material that is the most transparent, lightweight and flexible ever to conduct electricity. The material is invisible to the naked eye.

'Olympic rings' molecule olympicene stunning image taken

Researchers have succeeded in taking a stunning image of a newly synthesised molecule called olympicene. The molecule - just over a billionth of a metre across - gets its name because its five linked rings resemble the Olympic symbol. It was first made by collaborators at the University of Warwick in the UK.

They teamed up with IBM researchers, who in 2009 pioneered the technique of single-molecule imaging with its non-contact atomic force microscopy. The team, based at IBM Research Zurich, announced its first success with a molecule called pentacene, five linked hexagonal rings of carbon all in a line.

But it was Professor Sir Graham Richards, former head of Oxford University's chemistry department and member of the Royal Society of Chemistry (RSC) council, who first conceived of the idea to create a more Olympic-themed molecule along the same lines.

"I was in a committee meeting of the Royal Society of Chemistry where we were trying to think of what we could do to mark the Olympics," Prof Richards said. "It occurred to me that the molecule that I had drawn looked very much like the Olympic rings, and it had never been made."

The University of Warwick was tapped by the RSC to make the molecule for the first time. University of Warwick researchers Anish Mistry and David Fox undertook the task of developing a chemical recipe for the molecule, and took preliminary images of it using a technique called scanning tunnelling microscopy. But no approach gives such detailed images of single molecules as non-contact atomic force microscopy, in which a single, even tinier molecule of carbon monoxide is used as a kind of record needle to probe the grooves of molecules with unprecedented resolution.

The images show linked ring structures that are reminiscent both of the Olympic rings and a great many compounds made from rings of carbon atoms, including the "miracle material" graphene. However, Prof Richards hopes that olympicene's greatest contribution to chemistry is to bring more students into it. "Molecules of this nature could conceivably have commercial use, but my own feeling is that above all we want to excite an interest in chemistry provoked by the link with the Olympics," he said.

Tidal turbine powers up in Orkney

A tidal turbine being tested for use in the world’s first tidal turbine array in Islay on the West coast of Scotland has proved a success in hostile waters off the North of Orkney. Scottish Power Renewables fitted their HS1000 turbine at the end of last year and it has already been hooked up to the grid and is powering the Orkney Island of Eday.

AK-1000 tidal energy turbine before it is shipped to the European Marine Energy Centre test site in the Orkney Islands 

The 1MW machine is weighed down on the seabed 50 metres below the surface of a stretch of water called the Fall of Warness. It has some of the strongest tides in the world with an Atlantic swell colliding with the North Sea. Tides in the area can reach up to 8 knots in Spring tides.

Keith Anderson CEO of Scottish Power Renewables said:    The performance of the HS1000 has given us great confidence so far. We have already greatly developed our understanding of tidal power and this gives us confidence ahead of implementing large scale projects in Islay and the Pentland Firth.

Surveys have shown Islay and the Pentland Firth, on the South coast of Orkney, to have some of the best potential in the world for tidal energy projects. Those same studies indicate that up to 20% of the UK’s energy needs could be met by tidal energy.

At the moment the development of tidal turbines is hugely expensive – around £3m per megawatt built. However the industry is still in its relative infancy and the advances made in Orkney have the potential to make development of the technology more economic and efficient.

The usual criticisms levelled at wave and wind power have not, so far, been attributed to tidal turbines. Sitting 20m below the surface of the water they cannot attract the criticism of being an eyesore and because the blades move so slowly fish and marine mammals can easily pass between them.

Now that the technology has been proven in tough conditions off the coast of Orkney Scottish Power Renewables plans to start development on the ten turbines they plan to install in the Sound of Islay. That project will be the first of its’ kind in the world and will provide enough energy to supply Islay’s 3500 homes. One of the main benefits of tidal energy is of course its predictability and reliability. It is possible to calculate the exact amount of energy a tidal turbine will be producing at a certain time of the day, every day of the year. The same cannot be said of wave or wind power.

 

Map of Orkney area Map of Orkney area

Andrew MacDonald of the Islay Energy Trust said:We are at the end of the main grid and that means we suffer frequent electricity black outs. When the tidal project is up and running we’ll have our energy source sitting in our own back yard and the supply will be far more consistent.

 

Some concerns had been raised by local lobster fishermen in Islay about the impact of ten tidal turbines in the Sound of Islay. However they are now in support of the project after being assured that the turbines will not affect the channels where they work. It’s even hoped the bottom of the turbines could in fact provide attractive nesting areas for lobsters and crabs.

Climate scientists say they have solved riddle of rising sea

Massive extraction of groundwater can resolve a puzzle over a rise in sea levels in past decades, scientists in Japan said on Sunday. Global sea levels rose by an average of 1.8 millimetres (0.07 inches) per year from 1961-2003, according to data from tide gauges.

   

Global sea levels rose by an average of 1.8 millimetres (0.07 inches) per year from 1961-2003, according to data from tide gauges. But the big question is how much of this can be pinned to global warming.

In its landmark 2007 report, the UN's Nobel-winning Intergovernmental Panel on Climate Change (IPCC) ascribed 1.1mm (0.04 inches) per year to thermal expansion of the oceans -- water expands when it is heated -- and to meltwater from glaciers, icecaps and the Greenland and Antarctica icecaps. That left 0.7mm (0.03 inches) per year unaccounted for, a mystery that left many scientists wondering if the data were correct or if there were some source that had eluded everyone.

A team led by Yadu Pokhrel of the University of Tokyo say the answer lies in water that is extracted from underground aquifers, rivers and lakes for human development but is never replenished. The water eventually makes it to the ocean through rivers and evaporation in the soil, they note. Groundwater extraction is the main component of additions that account for the mystery gap, which is based on computer modelling.

"Together, unsustainable groundwater use, artificial reservoir water impoundment, climate-driven change in terrestrial water storage and the loss of water from closed basins have contributed a sea-level rise of 0.77mm (0.031 inches) per year between 1961 and 2003, about 42 percent of the observed sea-level rise," it says. The probe seeks to fill one of the knowledge gaps in the complex science of climate change.

Researchers admit to many unknowns about how the oceans respond to warming, and one of them is sea-level rise, an important question for hundreds of millions of coastal dwellers. Just a tiny rise, if repeated year on year, can eventually have a dramatic impact in locations that are vulnerable to storm surges or the influx of saltwater into aquifers or coastal fields.

In its 2007 Fourth Assessment Report, the IPCC said the oceans would rise by between 18 and 59 centimetres (seven to 23 inches) by the century's end. But this estimate did not factor in meltwater from the mighty Greenland and Antarctic ice sheets. A study published last year by the Oslo-based Arctic Monitoring and Assessment Project (AMAP) said sea levels would rise, on current melting trends, by 90 cms to 1.6 metres (3.0 to 5.3 feet) by 2100.