The oft-repeated—and often dismissed—warning that you’re more likely to catch a cold when it’s cold may have a scientific basis. In the Proceedings of the National Academy of Sciences in January, immunobiologist Ellen F. Foxman ’93, a research fellow at the Yale School of Medicine, and her colleagues showed, using mouse cells, that lower temperatures can impair the body’s immune response to rhinoviruses—allowing the viruses that cause the common cold to invade and replicate.


As more states legalize marijuana, the debate about its effects continues. Emily Ansell, assistant professor of psychiatry, and her colleagues monitored 43 men and women, most in their 20s, who reported on their marijuana, alcohol, and tobacco use over two weeks. In research that appeared online in Drug and Alcohol Dependence in January, Ansell’s team reported that pot was associated with increased impulsivity and hostile behavior and perceptions, and that effects on impulsivity lasted at least one additional day beyond actual use.


Expanding Medicaid, the federal insurance program for the poor, costs less than one might think. An analysis of Medicaid expansion in the 1980s and 1990s shows it has paid off in the form of higher tax payments, says economist Amanda E. Kowalski. In a National Bureau of Economic Research Working Paper released in January, Kowalski and colleagues estimate that when children covered under the program reach age 60, the federal government will have recouped 56 cents for every dollar invested (adjusted for inflation). That number doesn’t account for the higher state taxes also paid.

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