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William Horwitz
William Horwitz (1918 – September 27, 2006 in Olney, Maryland) was an analytical chemist who is notable for formulating a description of the relationship between the variability of chemical measurements and the concentration of the analyte. This relationship, called the Horwitz curve applies only to the between-laboratory variability of measurements. * w = weight percent of analyte in sample -w/w * C = mass fraction of analyte in sample imensionless= w / 100%-w/w * predicted RSD (relative standard deviation) = 2^(1-0.5*log(C))% Horwitz worked for the U.S. Food and Drug Administration (FDA) for 57 years until his retirement in 2000 and was head of the Association of Official Analytical Chemists for 24 years. The Horwitz curve is "one of the most intriguing relationships in modern analytical chemistry";Meija, Juris"A chemical uncertainty principle challenge" ''Analytical and Bioanalytical Chemistry'', vol. 387, no. 5, March 2007, p. 1583-1584, DOI: 10.1007/s00216-006-1059- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olney, Maryland
Olney is a U.S. census-designated place and an unincorporated area in Montgomery County, Maryland. It is located in the north central part of the county, north of Washington, D.C. Olney was largely agricultural until the 1960s, when growth of Washington, D.C.'s suburbs led to its conversion into a mostly residential area. It has a total population of 35,820 as of the 2020 United States census. In 2013 it was ranked #22 in ''Money'' magazine's "top-earning towns" edition of "America's Best Places to Live." In 2007, Olney ranked #17 on ''Money'' magazine's list of the 100 best places to live in the U.S. History In 1763, Richard Brooke received a patent for a tract of land located in the Province of Maryland.Sween, Jane C.; Offutt, William. ''Montgomery County: Centuries of Change''. American Historical Press, 1999. . Originally known as Mechanicsville, the village which became Olney was established in 1800. The area was mostly farmland, but it soon began attracting artisans. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analytical Chemistry
Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative analysis identifies analytes, while quantitative analysis determines the numerical amount or concentration. Analytical chemistry consists of classical, wet chemical methods and modern, instrumental methods. Classical qualitative methods use separations such as precipitation, extraction, and distillation. Identification may be based on differences in color, odor, melting point, boiling point, solubility, radioactivity or reactivity. Classical quantitative analysis uses mass or volume changes to quantify amount. Instrumental methods may be used to separate samples using chromatography, electrophoresis or field flow fractionation. Then qualitative and quantitative analysis can be performed, often with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horwitz Curve
Horwitz is a surname, current among Ashkenazi Jews. It is derived from the Yiddish pronunciation of the name of the town of Hořovice in Bohemia. For detailed historical background see the Horowitz page . Notable people with the surname include: * Arnold Horwitz (later Arnold Horween), American football player for Harvard Crimson and in the NFL * Bella Horwitz, 18th century Bohemian writer * Bernhard Horwitz (1807-1885), German chess player * Brian Horwitz (born 1982), American major league baseball outfielder * Jacob H. Horwitz (1892–1992), American businessman, philanthropist and fashion innovator. * Curly Howard, Jerome Lester Horwitz (1903 – 1952), Curly Howard, of the ''Three Stooges'' * David Horwitz (born 1994), Australian rugby union player * Kai Horwitz (born 1998), Chilean Olympic alpine skier * Maksymilian Horwitz, aka Henryk Walecki (1877–1937), leader and theoretician of the Polish communist movement * Morton Horwitz (born 1938), legal historian and law professor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food And Drug Administration (United States)
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food safety, tobacco products, caffeine products, dietary supplements, prescription and over-the-counter pharmaceutical drugs (medications), vaccines, biopharmaceuticals, blood transfusions, medical devices, electromagnetic radiation emitting devices (ERED), cosmetics, animal foods & feed and veterinary products. The FDA's primary focus is enforcement of the Federal Food, Drug, and Cosmetic Act (FD&C), but the agency also enforces other laws, notably Section 361 of the Public Health Service Act, as well as associated regulations. Much of this regulatory-enforcement work is not directly related to food or drugs, but involves such things as regulating lasers, cellular phones, and condoms, as well as control of disease in contexts varying fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AOAC International
AOAC International is a 501(c) non-profit scientific association with headquarters in Rockville, Maryland. It was founded in 1884 as the Association of Official Agricultural Chemists (AOAC) and became AOAC International in 1991. It publishes standardized, chemical analysis methods designed to increase confidence in the results of chemical and microbiological analyses. Government agencies and civil organizations often require that laboratories use official AOAC methods. AOAC is headquartered in Rockville, Maryland, and has approximately 3,000 members based in over 90 countries. History AOAC International, informally the AOAC, was founded September 8, 1884, as the Association of Official Agricultural Chemists, by the United States Department of Agriculture (USDA), to establish uniform chemical analysis methods for analyzing fertilizers. In 1927, sponsorship was moved to the newly formed Food, Drug and Insecticide organization which become the Food and Drug Administration (FDA) in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variance-to-mean Ratio
In probability theory and statistics, the index of dispersion, dispersion index, coefficient of dispersion, relative variance, or variance-to-mean ratio (VMR), like the coefficient of variation, is a normalized measure of the dispersion of a probability distribution: it is a measure used to quantify whether a set of observed occurrences are clustered or dispersed compared to a standard statistical model. It is defined as the ratio of the variance \sigma^2 to the mean \mu,'' :D = . It is also known as the Fano factor, though this term is sometimes reserved for ''windowed'' data (the mean and variance are computed over a subpopulation), where the index of dispersion is used in the special case where the window is infinite. Windowing data is frequently done: the VMR is frequently computed over various intervals in time or small regions in space, which may be called "windows", and the resulting statistic called the Fano factor. It is only defined when the mean \mu is non-zero, and is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1918 Births
This year is noted for the end of the World War I, First World War, on the eleventh hour of the eleventh day of the eleventh month, as well as for the Spanish flu pandemic that killed 50–100 million people worldwide. Events Below, the events of World War I have the "WWI" prefix. January * January – 1918 flu pandemic: The "Spanish flu" (influenza) is first observed in Haskell County, Kansas. * January 4 – The Finnish Declaration of Independence is recognized by Russian Soviet Federative Socialist Republic, Soviet Russia, Sweden, German Empire, Germany and France. * January 9 – Battle of Bear Valley: U.S. troops engage Yaqui people, Yaqui Native American warriors in a minor skirmish in Arizona, and one of the last battles of the American Indian Wars between the United States and Native Americans. * January 15 ** The keel of is laid in Britain, the first purpose-designed aircraft carrier to be laid down. ** The Red Army (The Workers and Peasants Red Army) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2006 Deaths
File:2006 Events Collage V1.png, From top left, clockwise: The 2006 Winter Olympics open in Turin; Twitter is founded and launched by Jack Dorsey; The Nintendo Wii is released; Montenegro votes to declare independence from Serbia; The 2006 FIFA World Cup in Germany is won by Italy; Gol Transportes Aéreos Flight 1907 crashes in the Amazon rainforest after a mid-air collision with an Embraer Legacy 600 business jet; The 2006 Yogyakarta earthquake kills over 5,700 people; The IAU votes on the definition of "planet", which demotes Pluto and other Kuiper belt objects and redefines them as "dwarf planets"., 300x300px, thumb rect 0 0 200 200 2006 Winter Olympics rect 200 0 400 200 Twitter rect 400 0 600 200 Nintendo Wii rect 0 200 300 400 IAU definition of planet rect 300 200 600 400 2006 Montenegrin independence referendum rect 0 400 200 600 2006 Yogyakarta earthquake rect 200 400 400 600 Gol Transportes Aéreos Flight 1907 rect 400 400 600 600 2006 FIFA World Cup 2006 was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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