Obese women may be putting themselves at greater risk of breast cancer by not undergoing regular screening. According to new research by Dr. Nisa Maruthur and her team from The John Hopkins University School of Medicine in Baltimore, USA, seriously obese women are significantly less likely to say they have undergone a recent mammography than normal weight women, especially if they are white. Maruthur's findings are published online this week in Springer's Journal of General Internal Medicine.

The first U.S. charter school opened in 1992. Since then the number of charters has grown to more than 4,000 in 40 states, serving 1.2 million students, according to RAND, a nonprofit research organization based in Santa Monica, California.

Students at charter schools graduate and attend college at significantly higher rates than students at traditional public schools, according to a Rand Corp. study led by a Michigan State University scholar.The study, which offers mixed overall results for charter school advocates, comes amid a national debate over President Obama's endorsement of charter schools, which are experimental public schools that operate independently of the local school board.

'Adaptation to exercise' is a familiar phenomenon, even if the phrase is not: A sedentary person takes up jogging and can barely make it around the block. After jogging regularly for a few weeks, the person can jog a mile, then two, then three. With regular exercise, the body adapts, becoming fitter and more efficient. The heart can pump more blood, delivering more oxygen to the muscles. The muscles get stronger, and so on.

A lack of Vitamin D, due to reduced sunlight, has been linked to depression and the symptoms of Seasonal Affective Disorder (SAD), but research by the University of Warwick shows there is no clear link between the levels of vitamin D in the blood and depression.

Exposure to sunlight stimulates vitamin D in the skin and a shortage of sunlight in the winter has been put forward as one possible cause of SAD. However Warwick Medical School researchers, led by Dr Oscar Franco, have discovered low levels of vitamin D in the blood may not be connected to depression.

Researchers trying to uncover the mechanisms that cause attention deficit hyperactivity disorder and conduct disorder have found an abnormality in the brains of adolescent boys suffering from the conditions, but not where they expected to find it.

Boys with either or both of these disorders exhibited a different pattern of brain activity than normally developing boys when they played a simple game that sometimes gave them a monetary reward for correct answers, according to a new study by a University of Washington research team.