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American babies mysteriously shrinking
ASHLEY COOPER/ALAMY
UPFRONT
How green’s algal power? ALGAE have been touted as a solution to environmental worries over biofuels, but they may be a long way from providing a truly green option. Unlike maize, soya beans and oilseed rape (canola), algal farms don’t take up valuable farmland, so algae-based biofuels don’t threaten food supplies. However, Andres Clarens at the University of Virginia in Charlottesville has modelled the environmental impacts of algal farms and concludes that they require six times as much energy as growing land plants – and emit significantly more greenhouse gases (Environmental Science and Technology, DOI: 10.1021/es902838n). “You have to add a whole lot more fertilisers, and the environmental cost of producing these is the
primary drawback,” Clarens says. Using waste water instead of fertilisers helps, but not enough, he says. The only trick that tipped the balance in favour of algae in his models was to use nutrient-rich household waste like concentrated urine to fertilise the algae, but this would require new infrastructure and so is no short-term fix. Others say recent advances are overcoming these challenges. For instance, bioreactors are being developed as more efficient alternatives to open-pond algae farms. To date, they have been prohibitively expensive, but a group at Jacobs University in Bremen, Germany, is developing affordable reactors that could slash the environmental impact of algal farms.
–Algae certainly looks green–
Tsunami tip-off RECENT natural disasters have made it all too clear that we need cheap and simple ways to prepare for nature’s wrath. That’s the thinking behind a novel approach to tsunami detection, which would use the submarine cables that supply your broadband. Existing warning systems use pressure sensors on the seafloor to detect the weight of a tsunami in the water column above. Only five countries own such sensor arrays – the US, Australia,
“The 2004 Indian Ocean tsunami created an electric field big enough to be detected by voltmeters” Indonesia, Chile and Thailand – partly due to the high cost of installation. This lack of coverage leaves many countries vulnerable to a tsunami strike. Now a team led by Manoj Nair at the National Oceanic and Atmospheric Administration in Boulder, Colorado, have proposed a cheaper way to detect an approaching tsunami: use 6 | NewScientist | 30 January 2010
undersea telecommunications cables to detect its electric field. Such fields are created as electrically charged salts in seawater pass through the Earth’s magnetic field. Computer modelling by Nair’s team shows that the electric field generated by the tsunami that struck south-east Asia in 2004 induced voltages of up to 500 millivolts. Their calculations show this is big enough to be detected by voltmeters placed at the end of the fibre-optic and copper cables that carpet the floor of the Indian Ocean. The work will appear in the journal Earth, Planets and Space. The idea has its limitations, though. Cables would not reveal the exact location or direction of the tsunami, and you would have to subtract noise created by fluctuations in the Earth’s magnetic field, tides and the cable itself to avoid misleading signals. Still, “it seems promising”, says Bill McGuire of University College London. But he points out that it’s just as important to set up a system to quickly pass on warnings to coastal towns after a tsunami has been detected.
Family planning THINKING of starting a family? There’s now a screening service to enable you and your partner to check if you are carrying genes for serious genetic diseases. For $349, Counsyl of Redwood City, California, runs genetic tests on saliva samples to see if prospective parents carry mutations that lie behind more than 100 inherited conditions. Many of the mutations involved are “recessive” variants that cause disease only when
passed on by both parents – and so can lie hidden in families for generations. Counsyl is working with fertility clinics so that couples at high risk can have IVF with pre-implantation screening to select healthy embryos. Some geneticists fear that the results may cause unnecessary worry and subsequent medical costs. “Once you get up to about 100 conditions, the odds are that everybody’s going to be a carrier,” suggests Michael Watson of the American College of Medical Genetics in Bethesda, Maryland.
The mysterious shrinking babies BIRTHWEIGHTS in the US are falling but no one knows why, according to a study of 36.8 million infants born between 1990 and 2005. A 52-gram drop in the weight of full-term singletons – from an average of 3.441 to 3.389 kilograms – has left Emily Oken’s team at Harvard Medical School scratching their heads (Obstetrics & Gynecology, vol 115, p 357). It can’t be accounted for by an increase in caesarean sections or induced labours, which shorten
gestation. What’s more, women in the US now smoke less and gain more weight during pregnancy, which should make babies heavier. Oken suggests that unmeasured factors, such as diet or exercise, could explain why babies are being born lighter. “For your average baby, 50 grams probably makes no difference at all,” she stresses. But those born substantially lighter could be at increased risk of heart disease and diabetes later in life.
UPFRONT
How green’s algal power? ALGAE have been touted as a solution to environmental worries over biofuels, but they may be a long way from providing a truly green option. Unlike maize, soya beans and oilseed rape (canola), algal farms don’t take up valuable farmland, so algae-based biofuels don’t threaten food supplies. However, Andres Clarens at the University of Virginia in Charlottesville has modelled the environmental impacts of algal farms and concludes that they require six times as much energy as growing land plants – and emit significantly more greenhouse gases (Environmental Science and Technology, DOI: 10.1021/es902838n). “You have to add a whole lot more fertilisers, and the environmental cost of producing these is the
primary drawback,” Clarens says. Using waste water instead of fertilisers helps, but not enough, he says. The only trick that tipped the balance in favour of algae in his models was to use nutrient-rich household waste like concentrated urine to fertilise the algae, but this would require new infrastructure and so is no short-term fix. Others say recent advances are overcoming these challenges. For instance, bioreactors are being developed as more efficient alternatives to open-pond algae farms. To date, they have been prohibitively expensive, but a group at Jacobs University in Bremen, Germany, is developing affordable reactors that could slash the environmental impact of algal farms.
–Algae certainly looks green–
Tsunami tip-off RECENT natural disasters have made it all too clear that we need cheap and simple ways to prepare for nature’s wrath. That’s the thinking behind a novel approach to tsunami detection, which would use the submarine cables that supply your broadband. Existing warning systems use pressure sensors on the seafloor to detect the weight of a tsunami in the water column above. Only five countries own such sensor arrays – the US, Australia,
“The 2004 Indian Ocean tsunami created an electric field big enough to be detected by voltmeters” Indonesia, Chile and Thailand – partly due to the high cost of installation. This lack of coverage leaves many countries vulnerable to a tsunami strike. Now a team led by Manoj Nair at the National Oceanic and Atmospheric Administration in Boulder, Colorado, have proposed a cheaper way to detect an approaching tsunami: use 6 | NewScientist | 30 January 2010
undersea telecommunications cables to detect its electric field. Such fields are created as electrically charged salts in seawater pass through the Earth’s magnetic field. Computer modelling by Nair’s team shows that the electric field generated by the tsunami that struck south-east Asia in 2004 induced voltages of up to 500 millivolts. Their calculations show this is big enough to be detected by voltmeters placed at the end of the fibre-optic and copper cables that carpet the floor of the Indian Ocean. The work will appear in the journal Earth, Planets and Space. The idea has its limitations, though. Cables would not reveal the exact location or direction of the tsunami, and you would have to subtract noise created by fluctuations in the Earth’s magnetic field, tides and the cable itself to avoid misleading signals. Still, “it seems promising”, says Bill McGuire of University College London. But he points out that it’s just as important to set up a system to quickly pass on warnings to coastal towns after a tsunami has been detected.
Family planning THINKING of starting a family? There’s now a screening service to enable you and your partner to check if you are carrying genes for serious genetic diseases. For $349, Counsyl of Redwood City, California, runs genetic tests on saliva samples to see if prospective parents carry mutations that lie behind more than 100 inherited conditions. Many of the mutations involved are “recessive” variants that cause disease only when
passed on by both parents – and so can lie hidden in families for generations. Counsyl is working with fertility clinics so that couples at high risk can have IVF with pre-implantation screening to select healthy embryos. Some geneticists fear that the results may cause unnecessary worry and subsequent medical costs. “Once you get up to about 100 conditions, the odds are that everybody’s going to be a carrier,” suggests Michael Watson of the American College of Medical Genetics in Bethesda, Maryland.
The mysterious shrinking babies BIRTHWEIGHTS in the US are falling but no one knows why, according to a study of 36.8 million infants born between 1990 and 2005. A 52-gram drop in the weight of full-term singletons – from an average of 3.441 to 3.389 kilograms – has left Emily Oken’s team at Harvard Medical School scratching their heads (Obstetrics & Gynecology, vol 115, p 357). It can’t be accounted for by an increase in caesarean sections or induced labours, which shorten
gestation. What’s more, women in the US now smoke less and gain more weight during pregnancy, which should make babies heavier. Oken suggests that unmeasured factors, such as diet or exercise, could explain why babies are being born lighter. “For your average baby, 50 grams probably makes no difference at all,” she stresses. But those born substantially lighter could be at increased risk of heart disease and diabetes later in life.