Computer programs can handle all sorts of data, from sums of money in bank accounts to sensor readings from scientific instruments. In many cases, the data are a set of discrete elements, such as temperatures. Moreover, some elements of a set may be larger in value than others, or they may exhibit some other relationship that allows you to rank them or put them in order.In mathematics, such a collection of elements is known as a partially ordered set, or poset. One example of a poset consists of an integer and all its positive divisors (excluding 1). For instance, the positive divisors of 42 a...

Make no mistake: Chocolate is not a health food. Indeed, most portions are loaded with empty calories from sugar and saturated fats.Several studies in recent years, however, have demonstrated that among sweets, chocolate may possess a few nutritional advantages over most calorie-rich alternatives. The latest of these good-news findings is a report that milk chocolate contains tiny amounts of conjugated linoleic acid, or CLA—a relatively low-profile fat that has been winning some big kudos.Most trans fats—ones containing a structural feature that make them solid at room temperature—have a bad r...

Anyone who has waited for a bus in the city has probably casually observed that, after an inordinately long wait, two or three buses often come along at the same time.The question of why such bunching seems to happen has prompted all sorts of speculation. Some claim that bus bunching is actually a rare occurrence, but passengers tend to forget the much larger number of times when a single bus arrives. Others posit that bus drivers simply like to travel in packs.Mathematical models that simulate traffic flow confirm that bus bunching is a real phenomenon. Even though buses leave their depot at...

Asian women tend to have much lower breast-cancer rates than their Western counterparts--unless they move to Europe or North America. Then the cancer’s incidence in these women begins to match local norms.This observation has suggested that something about the Western way of life, probably diet, promotes cancer--or that something about Eastern diets inhibits the development of breast malignancies. Strong support for the latter comes from a recent study by researchers at the University of Texas Medical Branch in Galveston and Weizmann Institute of Science in Rehovot, Israel.The study showed tha...

Twelve years ago, scientists uncovered a mechanism to explain why the folk remedy of eating cranberries fights urinary tract infections. It now appears that the medicinal powers of the pucker-inducing berries might extend to breast cancer as well.For years, Najla Guthrie and her colleagues at the University of Western Ontario in London have been exploring anticancer prospects of flavonoids, natural antioxidants, isolated from citrus juices (SN: 5/4/96, p. 287). Because deeply pigmented berries also contain dozens of such compounds--several with suspected anticancer activity--Guthrie recently t...