By 2050, the United States must cut its emissions by at least 80 percent below those created in the year 2000 if the world is to avoid potentially dangerous impacts of human-induced climate change, according to a new report. To avoid the most severe effects of climate change, the world must stabilize the concentration of heat trapping gases in the atmosphere at no more than 450 parts per million, according to researchers.

If you notice that your mood, energy level and motivation take a nosedive each November only to return to normal in April, you may have Seasonal Affective Disorder (SAD). "This condition, characterized by depression, exhaustion and lack of interest in people and regular activities, interferes with a person's outlook on life and ability to function properly," according to researchers. But people should not despair, because SAD is treatable.

It is estimated that more than 50 million Americans suffer from tinnitus, a condition where the patient experiences ringing or other head noises that are not produced by an external source. This disorder can occur in one or both ears, range in pitch from a low roar to a high squeal, and may be continuous or sporadic. This often debilitating condition has been linked to ear injuries, circulatory system problems, noise-induced hearing loss, wax build-up in the ear canal, medications harmful to the ear, ear or sinus infections, misaligned jaw joints, head and neck trauma, Ménière's disease, and an abnormal growth of bone of the middle ear.

It's a long-standing question: Can just the act of observing an experiment affect the results? According to a new study, if the experiment uses a fluorescent dye called acridine orange, the answer is a resounding "yes." A fluorescent marker, long used in imaging to help researchers watch membrane-bound vesicles as they exit a cell, can actually cause the vesicles to break open as soon as they're hit with light from a microscope. New research describes how to differentiate a microscopy side effect from the cell's true process.