Medical research

Gut epithelium muscles up against infection

To maximize absorption of nutrients from the diet, the intestinal mucous membrane has a large surface area. However, this also makes it vulnerable to attack from aggressive gut microbes. A new study by Uppsala University ...

Diseases, Conditions, Syndromes

Virus DNA spread across surfaces in hospital ward over 10 hours

Virus DNA left on a hospital bed rail was found in nearly half of all sites sampled across a ward within 10 hours and persisted for at least five days, according to a new study by UCL and Great Ormond Street Hospital (GOSH).

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Surface area

Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved then the definition of arc length of a curve. For polyhedra (objects with flat polygonal faces) the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere, are assigned surface area using their representation as parametric surfaces. This definition of the surface area is based on methods of infinitesimal calculus and involves partial derivatives and double integration.

General definition of surface area was sought by Henri Lebesgue and Hermann Minkowski at the turn of the twentieth century. Their work led to the development of geometric measure theory which studies various notions of surface area for irregular objects of any dimension. An important example is the Minkowski content of a surface.

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