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Lebedev, Pyotr Nikolaevich

(Encyclopedia)Lebedev, Pyotr Nikolaevich pyôˈtə nyĭkəlīˈəvĭch lāˈbyədyəf [key], 1866–1912, Russian physicist. The most noted Russian physicist of his time, he studied at Strasbourg and Berlin and was...

artesian well

(Encyclopedia)artesian well, deep drilled well through which water is forced upward under pressure. The water in an artesian well flows from an aquifer, which is a layer of very porous rock or sediment, usually san...

cold fusion

(Encyclopedia)cold fusion or low-temperature fusion, nuclear fusion of deuterium, an isotope of hydrogen, at or relatively near room temperature. Fusion, the reaction involved in the release of the destructive ener...

hygrometer

(Encyclopedia)hygrometer hīgrŏmˈətər [key], instrument used to measure the moisture content of a gas, as in determining the relative humidity of air. The temperature at which dew or frost forms is a measure of...

schnauzer

(Encyclopedia)schnauzer shnouˈzər [key], a sturdy, wirehaired dog developed in S Germany. There are three separate breeds of schnauzer distinguished by their size. The standard schnauzer is a medium-sized dog who...

activation energy

(Encyclopedia)CE5 Energy profile of an exothermic reaction: Although the total energy of the products is less than that of the reactants, the activation energy must be added to weaken or break existing bonds bef...

international monetary system

(Encyclopedia)international monetary system, rules and procedures by which different national currencies are exchanged for each other in world trade. Such a system is necessary to define a common standard of value ...

pitch, in music

(Encyclopedia)pitch, in music, the position of a tone in the musical scale, today designated by a letter name and determined by the frequency of vibration of the source of the tone. Pitch is an attribute of every m...

sunspots

(Encyclopedia)sunspots, dark, usually irregularly shaped spots on the sun's surface that are actually solar magnetic storms. The spots are darker because the temperature of the spots is lower than that of the surro...

Landau, Lev Davidovich

(Encyclopedia)Landau, Lev Davidovich lyĕf dəvēˈdəvĭch ləndouˈ [key], 1908–68, Soviet physicist, b. Baku, Azerbaijan. A child prodigy in mathematics, he entered Baku Univ. at 14; at 21 he received a doctor...