Immunology

Taking a census of all the immune cells in the human body

A team of environmental and molecular biologists at the Weizmann Institute of Science, working with a colleague from the Edmond and Lily Safra Children's Hospital and another with The Hebrew University-Hadassah Medical School, ...

Health

Women's Wellness: What's healthy pregnancy weight gain?

Like it or not, eating for two isn't a license to eat twice as much as usual. Use healthy lifestyle habits to manage your pregnancy weight gain, support your baby's health and make it easier to shed the extra pounds after ...

Overweight & Obesity

I go to the gym every day. Why can't I lose weight?

Liz is a typical 50-something woman, fit, 70 kg, 30% body fat. She goes to the gym every day, and runs for 35 minutes on the treadmill at 10km/h. But, as she tells me rather often, she can't lose weight. So what's going on ...

Health

Heavy runners risk injury in lightweight running shoes

Minimalist or lightweight running shoes, popularised as a safe alternative to conventional trainers, have been found to cause more harm than good for runners carrying extra weight, reveals research from the University of ...

Oncology & Cancer

Huge tumor removed from pregnant Bolivian woman

Bolivian doctors said Thursday they have successfully removed a 15-kilogram (33-pound) tumor from a woman in her 35th week of pregnancy who has since given birth to a healthy baby girl.

Kilogram

The kilogram or kilogramme (SI symbol: kg), also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is almost exactly equal to the mass of one liter of water. The avoirdupois (or international) pound, used in both the Imperial system and U.S. customary units, is defined as exactly 0.45359237 kg, making one kilogram approximately equal to 2.2046 avoirdupois pounds.

In everyday usage, the mass of an object given in kilograms is often referred to as its weight, which is the measure of the gravitational force—or heaviness—of an object. Weight given in kilograms is technically the non‑SI unit of measure known as the kilogram-force. The equivalent unit of force in the avoirdupois system of measurement is the pound-force. In strict scientific contexts, forces are typically measured with the SI unit newton.

The kilogram is the only SI base unit with an SI prefix as part of its name. It is also the only SI unit that is still directly defined by an artifact rather than a fundamental physical property that can be reproduced in different laboratories. Four of the seven base units in the SI system are defined relative to the kilogram so its stability is important.

The International Prototype Kilogram is kept in the custody of the International Bureau for Weights and Measures (BIPM) who hold it on behalf of the General Conference on Weights and Measures (CGPM). After the International Prototype Kilogram had been found to vary in mass over time, the International Committee for Weights and Measures (CIPM) recommended in 2005 that the kilogram be redefined in terms of a fundamental constant of nature. At its 24th meeting the General Conference on Weights and Measures (CGPM) agreed in principle that the kilogram should be redefined in terms of the Planck constant, but deferred a final decision until its next meeting, scheduled for 2014.

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