The kilogram is losing weight and many scientists agree that it's time to redefine it. They are hoping to redefine the kilogram by basing it on standards of universal constants rather than on an artifact standard. "The idea is to replace the single master kilogram with something based on physical constants, rather than an artifact that could be damaged accidentally," says one mechanical engineer.

  Everyone has known for decades that that smoking can kill, but until now no one really understood how cigarette smoke causes healthy lung cells to become cancerous. Researchers now show that hydrogen peroxide (or similar oxidants) in cigarette smoke is the culprit. This finding may help the tobacco industry develop "safer" cigarettes, while helping medical researchers develop new lung cancer treatments.

  The chlorinated solvent trichloroethene (TCE) has been found to be an increasingly problematic contaminant in groundwater. The detection of TCE recently forced the shut down of the water supply for the Greater Phoenix area municipalities of Paradise Valley and Scottsdale. TCE has been widely used as a cleaning agent and solvent for many military, commercial, and industrial applications. Its widespread use, along with its improper handling, storage, and disposal, has resulted in frequent detection of TCE in the groundwater. TCE has the potential to cause liver damage, malfunctions in the central nervous system and it is considered a likely human carcinogen. Now researchers have found an effective way to remove TCE from groundwater.

  Although rheumatoid arthritis (RA) is more predominant in women, the reasons for this are unclear. Many studies have examined the effects of estrogen on the risk and severity of RA, but the results are conflicting and controversial. A new study using data from the Women's Health Initiative clinical trials on hormone replacement therapy found that there were no significant differences in the risk of developing RA or the severity of RA between postmenopausal women who were on hormone replacement therapy and those who took placebos.

  Scientists have developed new sensitizers that should help an inexpensive type of solar cell to be more efficient. The sensitizers are based on the dye indoline.

  A study investigating the effects of class size on the achievement gap between high and low academic achievers suggests that high achievers benefit more from small classes than low achievers, especially at the kindergarten and first grade levels. "While decreasing class size may increase achievement on average for all types of students, it does not appear to reduce the achievement gap within a class."

  A highly specialized computer modeling technique has been instrumental in the design of a revolutionary new swimsuit which is now being hailed as the fastest in the world. Within a week of its launch athletes wearing the new swimsuit had broken three world records.

  Researchers have shown that they can effectively kill prostate cancer cells in both the laboratory and in experimental animal models by blocking a signaling protein that is key to the cancer's growth. The work proves that the protein, Stat5, is both vital to prostate cancer cell maintenance and that it is a viable target for drug therapy.

  Taking the supplement ginkgo biloba had no clear-cut benefit on the risk of developing memory problems, according to a new study. The three-year study involved 118 people age 85 and older with no memory problems. Half of the participants took ginkgo biloba extract three times a day and half took a placebo. During the study, 21 people developed mild memory problems, or questionable dementia. Although there was a trend favoring ginkgo, the difference between those who took gingko versus the placebo was not statistically significant.

  Screening breast cancers for three receptors could help doctors predict the likely survival of patients with brain metastases. A new study shows that patients with tumours that are negative for estrogen receptor, progesterone receptor and human epidermal growth receptor-2 or that are HER2+/ER- appear to be most at risk from developing brain metastases. Survival is also correlated to the triple receptor status.

  When plant cells divide, they assemble molecular building blocks into new cell walls made of carbohydrate and protein, but scientists know almost nothing about how this process occurs. Researchers have found that the first step in building new plant cell walls is the assembly of a scaffold made of structural proteins, a process similar to using a metal or wood scaffold to construct the walls of a building. Unlocking the secrets of how plants build cell walls could lead to better materials for the production of biofuels such as ethanol from cellulose, plant fibers that are a cheaper and more plentiful alternative to the starches currently used.

  The distinctive ability of mothers to identify the cries of their offspring is widely evident in nature, where it is critical to the survival of these offspring. Particular circuits in the brain, involving several regions in the cerebral cortex and limbic system, are distinctively activated when mothers distinguish the smiles and cries of their own infants from those of other infants.

  A team of scientists have found that the economic damages from hurricanes have increased in the U.S. over time due to greater population, infrastructure, and wealth on the U.S. coastlines, and not to any spike in the number or intensity of hurricanes.

  The progressive eye disease, age related macular degeneration, or AMD for short, doubles the risk of dying from a heart attack or stroke. AMD affects the center of the retina (macula) at the back of the eye, which is used for fine central vision tasks, such as reading and driving.