Growing up in poor neighborhoods: how much does it matter?

This article is a review of research on how much the life chances of children are affected by the socioeconomic and racial mix of their schools and neighborhoods. The social mix of a high school has little effect on students' chances of attending college or on white students' academic achievement. Evidence about the effect of the socioeconomic mix of schools or neighborhoods on achievement of elementary school students, on graduation rates of high school students, on teenage crime, and on early labor market experience is weak. Growing up in poor neighborhoods seems to increase black teenage pregnancy rates.     

Very-high-energy gamma rays from a distant quasar: how transparent is the universe?

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.     

Confronting coexistence in the United States: organic agriculture, genetic engineering, and the case of Roundup Ready® alfalfa

In agriculture, the principle of coexistence refers to a condition where different primary production systems can exist in the vicinity of each other, and can be managed in such a way that they affect each other as little as possible. Coexistence policies aim to ensure that farmers are able to freely grow the crops they choose—be they genetically engineered (GE), non-GE conventional, or organic. In the United States (US), the issue of coexistence has very recently come into sharp relief with the introduction of Roundup Ready^® (RR) alfalfa, a landmark court decision in 2007 (Geertson v. Johanns), and subsequent governmental actions, including the first Environmental Impact Statement on a GE crop. By contrast, in 2003 the European Union (EU) created a policy to manage coexistence and to address economic harms that may be caused by contamination. We briefly review the EU framework as an instructive resource. This policy analysis then looks at the US organic industry and its standards with respect to GE before turning to the case of RR alfalfa. With a focus on the field trial stage and on environmental assessments prior to market approval, the case reveals numerous problems in the existing regulatory framework as it pertains to coexistence and prevention of contamination of organic products with GE material. The paper concludes with specific policy recommendations for creating a more robust coexistence policy in the US.     

Episodic-like memory in rats: is it based on when or how long ago?

Recent experiments with rats suggest that they show episodic-like or what-where-when memory for a preferred food found on a radial maze. Although memory for when a salient event occurred suggests that rats can mentally travel in time to a moment in the past, an alternative possibility is that they remember how long ago the food was found. Three groups of rats were tested for memory of previously encountered food. The different groups could use only the cues of when, how long ago, or when + how long ago. Only the cue of how long ago food was encountered was used successfully. These results suggest that episodic-like memory in rats is qualitatively different from human episodic memory.     

Aging research: is long life in the blood?

Findings published this week in the Journal of the American Medical Association indicate that long-lived people have large lipoproteins--something associated with active young adults--in their blood, and that many of them carry a gene variant that influences cholesterol balance.