|
Vienna Standard Mean Ocean Water
Vienna Standard Mean Ocean Water (VSMOW) is an isotopic standard for water, that is, a particular sample of water whose proportions of different isotopes of hydrogen and oxygen are accurately known. VSMOW is distilled from ocean water and does not contain salt or other impurities. Published and distributed by the Vienna-based International Atomic Energy Agency in 1968, the standard and its essentially identical successor, VSMOW2, continue to be used as a reference material. Water samples made up of different isotopes of hydrogen and oxygen have slightly different physical properties. As an extreme example, heavy water, which contains two deuterium (2H) atoms instead of the usual, lighter hydrogen-1 (1H), has a melting point of and boiling point of . Different rates of evaporation cause water samples from different places in the water cycle to contain slightly different ratios of isotopes. Ocean water (richer in heavy isotopes) and rain water (poorer in heavy isotopes) roughly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmon Craig
Harmon Craig (March 15, 1926 – March 14, 2003) was an American geochemist who worked briefly for the University of Chicago (1951-1955) before spending the majority of his career at Scripps Institution of Oceanography (1955-2003). Craig was involved in numerous research expeditions, which visited the Great Rift Valley of East Africa, the crater of Loihi (now known as Kamaʻehuakanaloa), the Afar Depression of Ethiopia, Greenland's ice cores, and Yellowstone's geysers, among many others. This led to him being described as "the Indiana Jones of the Earth sciences", someone "whose overriding impulse was to get out and see the world they were studying". Craig made many significant discoveries in geochemistry. He is credited with establishing the field of carbon isotope geochemistry by characterizing carbon's stable isotopic signatures in various natural materials. This had immediate applications in radiocarbon dating. By studying stable and radioactive carbon isotopes in the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Error
The standard error (SE) of a statistic (usually an estimator of a parameter, like the average or mean) is the standard deviation of its sampling distribution or an estimate of that standard deviation. In other words, it is the standard deviation of statistic values (each value is per sample that is a set of observations made per sampling on the same population). If the statistic is the sample mean, it is called the standard error of the mean (SEM). The standard error is a key ingredient in producing confidence intervals. The sampling distribution of a mean is generated by repeated sampling from the same population and recording the sample mean per sample. This forms a distribution of different means, and this distribution has its own mean and variance. Mathematically, the variance of the sampling mean distribution obtained is equal to the variance of the population divided by the sample size. This is because as the sample size increases, sample means cluster more closely arou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Of Galilee
The Sea of Galilee (, Judeo-Aramaic languages, Judeo-Aramaic: יַמּא דטבריא, גִּנֵּיסַר, ), also called Lake Tiberias, Genezareth Lake or Kinneret, is a freshwater lake in Israel. It is the lowest freshwater lake on Earth and the second-lowest lake in the world (after the Dead Sea, a salt lake), with its elevation fluctuating between below sea level (depending on rainfall). It is approximately in circumference, about long, and wide. Its area is at its fullest, and its maximum depth is approximately .Data Summary: Lake Kinneret (Sea of Galilee) The lake is fed partly by underground springs, but its main source is the Jordan River, which flows through it from north to south with the outflow controlled by the Degania Dam. |
Lake Bracciano
Lake Bracciano () is a lake of volcanic origin in the Italian region of Lazio, northwest of Rome. It is the second largest lake in the region (second only to Lake Bolsena) and one of the major lakes of Italy. It has a circular perimeter of approximately . Its inflow is from precipitation runoff and percolation, and from underground springs, and its outflow is the Arrone. The lake owes its origin to intense volcanic and tectonic activity from 600,000 to 40,000 years ago, which created many small volcanoes in the ''Sabatino'' territory. The main magma chamber was situated under the present lake of Bracciano. Its collapse created the depressed area now occupied by the lake, which is not a crater lake. Some small craters and calderas are still recognisable around the lake and in the immediate vicinity (Martignano, Baccano, Sacrofano). Three towns border the lake, Bracciano, Anguillara Sabazia and Trevignano Romano. The lake is an important tourist attraction. As it serves as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commission On Isotopic Abundances And Atomic Weights
The Commission on Isotopic Abundances and Atomic Weights (CIAAW) is an international scientific committee of the International Union of Pure and Applied Chemistry (IUPAC) under its IUPAC Inorganic Chemistry Division, Division of Inorganic Chemistry. Since 1899, it is entrusted with periodic critical evaluation of atomic weights of chemical elements and other cognate data, such as the Isotope, isotopic composition of elements. The biennial CIAAW Standard atomic weight, Standard Atomic Weights are accepted as the authoritative source in science and appear worldwide on the periodic table wall charts. The use of CIAAW Standard Atomic Weights is also required legally, for example, in calculation of calorific value of natural gas (ISO 6976:1995), or in gravimetric preparation of primary reference standards in gas analysis (ISO 6142:2006). In addition, until 2019 the definition of the Kelvin, the SI unit for thermodynamic temperature, made direct reference to the isotopic composition of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampoule
An ampoule (also ampul and ampule) is a small sealed vial which is used to contain and preserve a sample, usually a solid or liquid. Ampoules are usually made of glass. Modern ampoules are most commonly used to contain pharmaceuticals and chemicals that must be protected from air and contaminants. They are hermetic seal, hermetically sealed by melting the thin top with an open flame, and usually opened by snapping off the neck. The space above the chemical may be filled with an inert gas before sealing. The walls of glass ampoules are usually sufficiently strong to be brought into a glovebox without any difficulty. Glass ampoules are more expensive than bottles and other simple containers, but there are many situations where their superior imperviousness to gases and liquids and all-glass interior surface are worth the extra cost. Examples of chemicals sold in ampoules are hypodermic needle, injectable pharmaceuticals, air-sensitive reagents like tetrakis(triphenylphosphine)pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plateau Station
Plateau Station is an inactive American research and South Pole—Queen Maud Land Traverse support base on the central Antarctic Plateau. Construction on the site started on December 13, 1965, and the first traverse team (named SPQML II) arrived in early 1966. The base was in continuous use until January 29, 1969, when it was closed but mothballed for future use, and was the most remote and coldest of any United States stations on the continent. It was also the site for the world's coldest measured average temperature for a month at that time, recorded in July 1968, at . History The station was operated and staffed by the National Science Foundation and United States Navy. A select team of four scientists and four navy personnel were on constant duty at the station, which was under the command of a naval medical doctor. Originally designed for two years of service, it was in use for three years. Until the Fuji Dome Station opened in 1995, it was the outpost at the highest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Firn
__NOTOC__ Firn (; from Swiss German "last year's", cognate with ''before'') is partially compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice. Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.35 g/cm3 to 0.9 g/cm3, and it can often be found underneath the snow that accumulates at the head of a glacier. Snowflakes are compressed under the weight of the overlying snowpack. Individual crystals near the melting point are semiliquid and slick, allowing them to glide along other crystal planes and to fill in the spaces between them, increasing the ice's density. Where the crystals touch, they bond together, squeezing the air between them to the surface or into bubbles. In the summer months, the crystal metamorphosis can occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California Institute Of Technology
The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes of technology in the United States that are devoted to the instruction of pure and applied sciences. The institution was founded as a preparatory and vocational school by Amos G. Throop in 1891 and began attracting influential scientists such as George Ellery Hale, Arthur Amos Noyes, and Robert Andrews Millikan in the early 20th century. The vocational and preparatory schools were disbanded and spun off in 1910, and the college assumed its present name in 1920. In 1934, Caltech was elected to the Association of American Universities, and the antecedents of NASA's Jet Propulsion Laboratory, which Caltech continues to manage and operate, were established between 1936 and 1943 under Theodore von Kármán. Caltech has six academic divisi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potomac River
The Potomac River () is in the Mid-Atlantic (United States), Mid-Atlantic region of the United States and flows from the Potomac Highlands in West Virginia to Chesapeake Bay in Maryland. It is long,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map. Retrieved August 15, 2011 with a Drainage basin, drainage area of , and is the fourth-largest river along the East Coast of the United States. More than 6 million people live within its drainage basin, watershed. The river forms part of the borders between Maryland and Washington, D.C., on the left descending bank, and West Virginia and Virginia on the right descending bank. Except for a small portion of its headwaters in West Virginia, the #North Branch Potomac River, North Branch Potomac River is considered part of Maryland to the low-water mark on the opposite bank. The South Branch Potomac River lies completely within the state of West Virginia except for its headwaters, which lie i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
