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Fighting environmental lead contamination leads to smarter kids

Lead abatement policies lead to smarter kids.
Here's some new research from Jessica Wolpaw Reyes highlighting a point that's not nearly as well-known as it should be. Public policies to remove brain-destroying lead from low-income communities pays off huge dividends: Childhood exposure to even low levels of lead can adversely affect neurodevelopment, behavior, and cognitive performance. This paper investigates the link between lead exposure and student achievement in Massachusetts. Panel data analysis is conducted at the school-cohort level for children born between 1991 and 2000 and attending 3rd and 4th grades between 2000 and 2009 at more than 1,000 public elementary schools in the state. Massachusetts is well-suited for this analysis both because it has been a leader in the reduction of childhood lead levels and also because it has mandated standardized achievement tests in public elementary schools for almost two decades. The paper finds that elevated levels of blood lead in early childhood adversely impact standardized test performance, even when controlling for community and school characteristics. The results imply that public health policy that reduced childhood lead levels in the 1990s was responsible for modest but statistically significant improvements in test performance in the 2000s, lowering the share of children scoring unsatisfactory on standardized tests by 1 to 2 percentage points. Public health policy targeting lead thus has clear potential to improve academic performance, with particular promise for children in low income communities. The transmission of social and academic disadvantage through childhood lead exposure is one of the most insidious forms of inequality in the United States.

October 06, 2012

Insects may have mechanical brains

As in, they don't think. They don't make decisions. They get an input and perform an action. That's it. Wasp has hints of a clockwork brain - life - 06 October 2012 - New Scientist
THE human brain might be the most complex object in the known universe, but a much simpler set of neurons is also proving to be a tough nut to crack. A tiny wasp has brain cells so small, physics predicts they shouldn't work at all. These miniature neurons might harbour subtle modifications, or they might work completely differently from all other known neurons - mechanically. The greenhouse whitefly parasite (Encarsia formosa) is just half a millimetre in length. It parasitises the larvae of whiteflies and so it has long been used as a natural pest-controller. To find out how its neurons have adapted to miniaturisation, Reinhold Hustert of the University of G�ttingen in Germany examined the insect's brain with an electron microscope. The axons - fibres that shuttle messages between neurons - were incredibly thin. Of 528 axons measured, a third were less than 0.1 micrometre in diameter, an order of magnitude narrower than human axons. The smallest were just 0.045 μm (Arthropod Structure & Development, doi.org/jfn). That's a surprise, because according to calculations by Simon Laughlin of the University of Cambridge and colleagues, axons thinner than 0.1 μm simply shouldn't work. Axons carry messages in waves of electrical activity called action potentials, which are generated when a chemical signal causes a large number of channels in a cell's outer membrane to open and allow positively charged ions into the axon. At any given moment some of those channels may open spontaneously, but the number involved isn't enough to accidentally trigger an action potential, says Laughlin - unless the axon is very thin. An axon thinner than 0.1 μm will generate an action potential if just one channel opens spontaneously (Current Biology, doi.org/frfwpz). "That makes the axon impossibly noisy," Laughlin says. Any "legitimate" action potentials will be drowned out. Hustert suggests that a neuron might get around this problem by firing bursts of action potentials to cut through the noise, but Laughlin is sceptical. "They'd be firing furiously all the time," he says, and every action potential costs energy. Instead, the neurons might not bother with conventional action potentials at all. "They could be sending signals mechanically," Laughlin says. The tiny axons might each carry a long rigid rod stretching down the centre. Pulling the rod could create a physical rather than electrical trigger for the release of a chemical that passes the signal on to the neighbouring neuron.

October 03, 2012

HIV has created a new medicine-resistant salmonella

Why HIV is More Evil Than We Could Have Imagined
A devastating Salmonella epidemic is ravaging parts of sub-Saharan Africa right now — and it appears that HIV gave this rapidly evolving form of Salmonella a major boost. According to a new study, the African HIV epidemic appears to have provided this strain of Salmonella with a large number of humans with weakened immune systems, giving it a place to evolve, and to spread rapidly. Worse still: the new, improved strain of Salmonella doesn't respond to the first set of antibiotics, meaning that doctors have to use more expensive drugs, instead. Just one more way that HIV is more evil than we ever knew. Called non-Typhoidal Salmonella (iNTS), the relatively new disease was generated by a new form of the bacteria Salmonella typhimurium that spread from two different focal hubs in Southern and Central Africa. It emerged in two separate waves, the first in 1960 and the second in 1977 (possibly from the Congo Basin).