may occur over and over
21CIA transnational health and economic activities — This article deals with activities of the U.S. Central Intelligence Agency related to human survival issues, emphasizing disease and basic needs such as water and agriculture. TOC CIA activities in this area include the preparation of National… …
22Health and Disease — ▪ 2009 Introduction Food and Drug Safety. In 2008 the contamination of infant formula and related dairy products with melamine in China led to widespread health problems in children, including urinary problems and possible renal tube… …
23ice in lakes and rivers — Introduction a sheet or stretch of ice forming on the surface of lakes and rivers when the temperature drops below freezing (0° C [32° F]). The nature of the ice formations may be as simple as a floating layer that gradually thickens, or it …
24Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… …
25international payment and exchange — ▪ economics Introduction international exchange also called foreign exchange respectively, any payment made by one country to another and the market in which national currencies are bought and sold by those who require them for such… …
26harbours and sea works — Introduction harbour also spelled harbor any part of a body of water and the manmade structures surrounding it that sufficiently shelters a vessel from wind, waves, and currents, enabling safe anchorage or the discharge and loading of… …
27tunnels and underground excavations — ▪ engineering Introduction Great tunnels of the world Great tunnels of the worldhorizontal underground passageway produced by excavation or occasionally by nature s action in dissolving a soluble rock, such as limestone. A vertical opening …
28Global Energy and Water Cycle Experiment — The Global Energy and Water Cycle Experiment (GEWEX) is a research program of the World Climate Research Programme intended to observe, comprehend and models the Earth s water cycle. The experiment also observes how much energy the Earth receives …
29Earth and Space Sciences — ▪ 1996 Introduction GEOLOGY AND GEOCHEMISTRY In 1995 significant developments took place in the realm of geologic mapping, which provides the foundation for the presentation and comparison of data in the Earth sciences. The most important… …
30Comparison of analog and digital recording — This article compares the two ways in which sound is recorded and stored. Actual sound waves consist of continuous variations in air pressure. Representations of these signals can be recorded using either digital or analog techniques. An analog… …
