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Proton Magnetometer
A proton magnetometer, also known as a proton precession magnetometer (PPM), uses the principle of Earth's field NMR, Earth's field nuclear magnetic resonance (EFNMR) to measure very small variations in the Earth's magnetic field, allowing ferrous objects on land and at sea to be detected. It is used in land-based archaeology to map the positions of demolished walls and buildings, and at sea to locate wrecked ships, sometimes for recreational diving. PPMs were once widely used in mineral exploration. They have largely been superseded by Magnetometer#Overhauser effect magnetometer, Overhauser effect magnetometers and alkali vapour (Magnetometer#Caesium vapour magnetometer, caesium, rubidium, and Magnetometer#Potassium vapour magnetometer, potassium) or helium magnetometers, which sample faster and are more sensitive. Principles of operation A direct current flowing in a solenoid creates a strong magnetic field around a hydrogen-rich fluid (kerosine and decane are popular; wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1967 Proton Magnetometer
Events January * January 1 – Canada begins a year-long celebration of the 100th anniversary of Canadian Confederation, Confederation, featuring the Expo 67 World's Fair. * January 6 – Vietnam War: United States Marine Corps and Army of the Republic of Vietnam troops launch ''Operation Deckhouse Five'' in the Mekong Delta. * January 8 – Vietnam War: Operation Cedar Falls starts, in an attempt to eliminate the Iron Triangle (Vietnam), Iron Triangle. * January 13 – A military coup occurs in Togo under the leadership of Étienne Eyadema. * January 15 – Louis Leakey announces the discovery of pre-human fossils in Kenya; he names the species ''Proconsul nyanzae, Kenyapithecus africanus''. * January 23 ** In Munich, the trial begins of Wilhelm Harster, accused of the murder of 82,856 Jews (including Anne Frank) when he led German security police during the German occupation of the Netherlands. He is eventually sentenced to 15 years in prison. ** Milton Keynes in England is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proton–gyromagnetic Ratio
The nucleon magnetic moments are the intrinsic magnetic dipole moments of the proton and neutron, symbols ''μ''p and ''μ''n. The nucleus of an atom comprises protons and neutrons, both nucleons that behave as small magnets. Their magnetic strengths are measured by their magnetic moments. The nucleons interact with normal matter through either the nuclear force or their magnetic moments, with the charged proton also interacting by the Coulomb force. The proton's magnetic moment was directly measured in 1933 by Otto Stern team in University of Hamburg. While the neutron was determined to have a magnetic moment by indirect methods in the mid-1930s, Luis Alvarez and Felix Bloch made the first accurate, direct measurement of the neutron's magnetic moment in 1940. The proton's magnetic moment is exploited to make measurements of molecules by proton nuclear magnetic resonance. The neutron's magnetic moment is exploited to probe the atomic structure of materials using scattering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diving Support Equipment
Diving support equipment facilitates a diving operation. It is either not taken into the water during the dive, such as the gas panel and compressor, or is not integral to the actual diving, being there to make the dive easier or safer, such as a surface decompression chamber. Some equipment, like a diving stage, is not easily categorised as diving or support equipment and may be considered either. Breathing gas equipment * * * * * * * * * * * * * * * * * * * * * * * * Platforms * ** ** ** * ** * Habitats * ** ** ** ** ** ** ** Decompression equipment * * * * * Deployment systems * * * * * * * – A suspended foot support allowing divers to use a leg to help lift themselves from the water into the boat. * * * * Remotely controlled underwater vehicles * * * * * * * * * * * * * * * * * * * * * * * Dive planning and recording equipment * * * * * * Safety equipment * * * * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indiana
Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the south and southeast, and the Wabash River and Illinois to the west. Nicknamed "the Hoosier State", Indiana is the List of U.S. states and territories by area, 38th-largest by area and the List of U.S. states and territories by population, 17th-most populous of the List of states and territories of the United States, 50 states. Its capital and largest city is Indianapolis. Indiana was admitted to the Union as the 19th state on December 11, 1816. Indigenous peoples of the Americas, Indigenous resistance to American settlement was broken with defeat of the Tecumseh's confederacy in 1813. The new settlers were primarily Americans of British people, British ancestry from the East Coast of the United States, eastern seaboard and the Upland South ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angel Mounds
Angel Mounds State Historic Site (Smithsonian trinomial, 12 VG 1), an expression of the Mississippian culture, is an archaeological site managed by the Indiana State Museum and Historic Sites that includes more than of land about southeast of present-day Evansville, Indiana, Evansville, in Vanderburgh County, Indiana, Vanderburgh and Warrick County, Indiana, Warrick counties in Indiana. The large residential and agricultural community was constructed and inhabited from AD 1100 to AD 1450, and served as the political, cultural, and economic center of the Angel chiefdom. It extended within of the Ohio River valley to the Green River (Kentucky), Green River in present-day Kentucky. The town had as many as 1,000 inhabitants inside the walls at its peak, and included a complex of thirteen Earthworks (archaeology), earthen mounds, hundreds of home sites, a palisade (stockade), and other structures. Designated a National Historic Landmark in 1964, the property also includes an interp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoremanent Magnetization
When an igneous rock cools, it acquires a thermoremanent magnetization (TRM) from the Earth's field. TRM can be much larger than it would be if exposed to the same field at room temperature (see isothermal remanence). This remanence can also be very stable, lasting without significant change for millions of years. TRM is the main reason that paleomagnetists are able to deduce the direction and magnitude of the ancient Earth's field. History As early as the eleventh century, the Chinese were aware that a piece of iron could be magnetized by heating it until it was red hot, then quenching in water. While quenching it was oriented in the Earth's field to get the desired polarity. In 1600, William Gilbert published ''De Magnete'' (1600), a report of a series of meticulous experiments in magnetism. In it, he described the quenching of a steel rod in the direction of the Earth's field, and he may have been aware of the Chinese work. In the early 20th century, a few investigators foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford University
The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the second-oldest continuously operating university globally. It expanded rapidly from 1167, when Henry II prohibited English students from attending the University of Paris. When disputes erupted between students and the Oxford townspeople, some Oxford academics fled northeast to Cambridge, where they established the University of Cambridge in 1209. The two English ancient universities share many common features and are jointly referred to as ''Oxbridge''. The University of Oxford comprises 43 constituent colleges, consisting of 36 semi-autonomous colleges, four permanent private halls and three societies (colleges that are departments of the university, without their own royal charter). and a range of academic departments that are organised into four divisions. Each college ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Martin Aitken
Martin Jim Aitken FRS (11 March 1922 – 13 June 2017) was a British archaeometrist. Aitken was born in Stamford, Lincolnshire, and studied physics at Wadham College, Oxford. He was a fellow of Linacre College, Oxford. He was Professor of Archaeometry at the University of Oxford from 1985 until he retired in 1989. Aitken organised annual meetings which became the Symposium on Archaeometry and Archaeological Prospection". He had an interest in absolute dating: radiocarbon dating from 1957, thermoluminescence dating from the 1960s, and later helped develop optically stimulated luminescence In physics, optically stimulated luminescence (OSL) is a method for measuring doses from ionizing radiation. It is used in at least two applications: * Luminescence dating of ancient materials: mainly geological sediments and sometimes fired pot ... as a dating method dating. He died in June 2017 at the age of 95. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Banded Iron Formation
Banded iron formations (BIFs; also called banded ironstone formations) are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iron-poor chert. They can be up to several hundred meters in thickness and extend laterally for several hundred kilometers. Almost all of these formations are of Precambrian age and are thought to record the Great Oxygenation Event, oxygenation of the Earth's oceans. Some of the Earth's oldest rock formations, which formed about (Year#SI prefix multipliers, Ma), are associated with banded iron formations. Banded iron formations are thought to have formed in sea water as the result of oxygen production by photosynthesis, photosynthetic cyanobacteria. The oxygen combined with dissolved iron in Earth's oceans to form insoluble iron oxides, which precipitated out, forming a thin layer on the ocean floor. Each band is similar to a varve, resulting from cyclic variations in oxygen production. Banded iron formations we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Pole
The geomagnetic poles are antipodal points where the axis of a best-fitting dipole intersects the surface of Earth. This ''theoretical'' dipole is equivalent to a powerful bar magnet at the center of Earth, and comes closer than any other point dipole model to describing the magnetic field observed at Earth's surface. In contrast, the magnetic poles of the actual Earth are not antipodal; that is, the line on which they lie does not pass through Earth's center. Owing to the motion of fluid in the Earth's outer core, the actual magnetic poles are constantly moving (secular variation). However, over thousands of years, their direction averages to the Earth's rotation axis. On the order of once every half a million years, the poles reverse (i.e., north switches place with south) although the time frame of this switching can be anywhere from every 10 thousand years to every 50 million years. The poles also swing in an oval of around in diameter daily due to solar wind deflecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parts Per Million
In science and engineering, the parts-per notation is a set of pseudo-units to describe the small values of miscellaneous dimensionless quantity, dimensionless quantities, e.g. mole fraction or mass fraction (chemistry), mass fraction. Since these fraction (mathematics), fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are * parts-per-million - ppm, * parts-per-billion - ppb, * parts-per-trillion - ppt, * parts-per-quadrillion - ppq, This notation is not part of the International System of Units - SI system and its meaning is ambiguous. Applications Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
