The dose makes the poison, it is often said, and it is true. Lots of medicines and chemicals are harmless or beneficial in reasonable quantities but dangerous in high quantities. What about CO2 in plants? Plants need it for food but they also recognize too much is a bad thing. 

Biologists have been studying a long-standing mystery concerning the way plants reduce the numbers of their breathing pores in response to rising carbon dioxide levels in the atmosphere.

The authors report the discovery of a new genetic pathway in plants, made up of four genes from three different gene families that control the density of breathing pores—or "stomata"—in plant leaves in response to elevated CO₂ levels.

There are numerous ways to address carbon emissions but are we choosing the right approaches? America and Europe have invested heavily in subsidizing solar and wind generation and solar panels - but critics contend that the same money spent modernizing older buildings would have done far more than funding Chinese corporations or wealthy homeowners has.

Low-carbon energy won't cost  more than what is currently spent on today's fossil-dominated energy system, according to new research from the International Institute for Applied Systems Analysis (IIASA) and partners.

Evolutionary adaptations have allowed Tibetans to have no trouble living at 13,000 feet, but how they became able to conquer the harsh environment of hypoxia has long been a mystery.

Medicine is advancing rapidly and it always has risks, but in early going the risks are going to be greater. A paper found that the risk of patient harm increased two-fold in 2006, the year when teaching hospitals nationwide embraced the pursuit of minimally invasive robotic surgery for prostate cancer.

What is the impact of volcanic sulfate emissions on climate? Researchers have completed the most accurate and precise reconstruction to date of historic volcanic sulfate emissions in the Southern Hemisphere, derived from a large number of individual ice cores collected at various locations across Antarctica and is the first annually resolved record extending through the Common Era - the last 2,000 years of human history.

Reconstructions of the past are critical to creating accurate model simulations used to assess natural versus anthropogenic climate forcing. Such model simulations underpin environmental policy decisions including those aimed at regulating greenhouse gas and aerosol emissions to mitigate projected global warming. 

The small intestine is not easy to examine. X-rays, MRIs and ultrasound images provide snapshots but each suffers limitations.
 

The average human small intestine is roughly 23 feet long and 1 inch thick. Sandwiched between the stomach and large intestine, it is where much of the digestion and absorption of food takes place. It is also where symptoms of irritable bowel syndrome, celiac disease, Crohn's disease and other gastrointestinal illnesses occur. To assess the organ, doctors typically require patients to drink a thick, chalky liquid called barium. Doctors then use X-rays, magnetic resonance imaging and ultrasounds to assess the organ, but these techniques are limited with respect to safety, accessibility and lack of adequate contrast, respectively.