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life and Earth sciences. === Narrow definition === Geochemists define the biosphere as being the total sum of living organisms (the "biomass" or "biota" as referred to by biologists and ecologists). In this sense, the biosphere is but one of four separate components of the geochemical model, the other three being geosphere, hydrosphere, and atmosphere. When these four component spheres are combined into one system, it is known as the ecosphere. This term was coined during the 1960s and encompasses both biological and physical components of the planet. The Second International Conference on Closed Life Systems defined biospherics as the science and technology of analogs and models of Earth's biosphere; i.e., artificial Earth-like biospheres. Others may include the creation of artificial non-Earth biospheres—for example, human-centered biospheres or a native Martian biosphere—as part of the topic of biospherics. == Earth's biosphere == === Overview === Currently, the total number of living cells on the Earth is estimated to be 1030; the total number since the beginning of Earth, as 1040, and the total number for the entire time of a habitable planet Earth as 1041. This is much larger than the total number of estimated stars (and Earth-like planets) in the observable universe as 1024, a number which is more than all the grains of beach sand on planet Earth; but less than the total number of atoms estimated in the observable universe as 1082; and the estimated total number of stars in an inflationary universe (observed and unobserved), as 10100. === Age === The earliest evidence for life on Earth includes biogenic graphite found in 3.7 billion-year-old metasedimentary rocks from Western Greenland and microbial mat fossils found in 3.48 billion-year-old sandstone from Western Australia. More recently, in 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in Western
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Australia. In 2017, putative fossilized microorganisms (or microfossils) were announced to have been discovered in hydrothermal vent precipitates in the Nuvvuagittuq Belt of Quebec, Canada that were as old as 4.28 billion years, the oldest record of life on earth, suggesting "an almost instantaneous emergence of life" after ocean formation 4.4 billion years ago, and not long after the formation of the Earth 4.54 billion years ago. According to biologist Stephen Blair Hedges, "If life arose relatively quickly on Earth ... then it could be common in the universe." === Extent === Every part of the planet, from the polar ice caps to the equator, features life of some kind. Recent advances in microbiology have demonstrated that microbes live deep beneath the Earth's terrestrial surface and that the total mass of microbial life in so-called "uninhabitable zones" may, in biomass, exceed all animal and plant life on the surface. The actual thickness of the biosphere on Earth is difficult to measure. Birds typically fly at altitudes as high as 1,800 m (5,900 ft; 1.1 mi) and fish live as much as 8,372 m (27,467 ft; 5.202 mi) underwater in the Puerto Rico Trench. There are more extreme examples for life on the planet: Rüppell's vulture has been found at altitudes of 11,300 metres (37,100 feet; 7.0 miles); bar-headed geese migrate at altitudes of at least 8,300 m (27,200 ft; 5.2 mi); yaks live at elevations as high as 5,400 m (17,700 ft; 3.4 mi) above sea level; mountain goats live up to 3,050 m (10,010 ft; 1.90 mi). Herbivorous animals at these elevations depend on lichens, grasses, and herbs. Life forms live in every part of the Earth's biosphere, including soil, hot springs, inside rocks at least 19 km (12 mi) deep underground, and at least 64 km (40 mi)
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high in the atmosphere. Marine life under many forms has been found in the deepest reaches of the world ocean while much of the deep sea remains to be explored. Under certain test conditions, microorganisms have been observed to survive the vacuum of outer space. The total amount of soil and subsurface bacterial carbon is estimated as 5 × 1017 g. The mass of prokaryote microorganisms—which includes bacteria and archaea, but not the nucleated eukaryote microorganisms—may be as much as 0.8 trillion tons of carbon (of the total biosphere mass, estimated at between 1 and 4 trillion tons). Barophilic marine microbes have been found at more than a depth of 10,000 m (33,000 ft; 6.2 mi) in the Mariana Trench, the deepest spot in the Earth's oceans. In fact, single-celled life forms have been found in the deepest part of the Mariana Trench, by the Challenger Deep, at depths of 11,034 m (36,201 ft; 6.856 mi). Other researchers reported related studies that microorganisms thrive inside rocks up to 580 m (1,900 ft; 0.36 mi) below the sea floor under 2,590 m (8,500 ft; 1.61 mi) of ocean off the coast of the northwestern United States, as well as 2,400 m (7,900 ft; 1.5 mi) beneath the seabed off Japan. Culturable thermophilic microbes have been extracted from cores drilled more than 5,000 m (16,000 ft; 3.1 mi) into the Earth's crust in Sweden, from rocks between 65–75 °C (149–167 °F). Temperature increases with increasing depth into the Earth's crust. The rate at which the temperature increases depends on many factors, including the type of crust (continental vs. oceanic), rock type, geographic location, etc. The greatest known temperature at which microbial life can exist is 122 °C (252 °F) (Methanopyrus kandleri Strain 116). It is likely that the limit of life in
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the "deep biosphere" is defined by temperature rather than absolute depth. On 20 August 2014, scientists confirmed the existence of microorganisms living 800 m (2,600 ft; 0.50 mi) below the ice of Antarctica. Earth's biosphere is divided into several biomes, inhabited by fairly similar flora and fauna. On land, biomes are separated primarily by latitude. Terrestrial biomes lying within the Arctic and Antarctic Circles are relatively barren of plant and animal life. In contrast, most of the more populous biomes lie near the equator. === Annual variation === == Artificial biospheres == Experimental biospheres, also called closed ecological systems, have been created to study ecosystems and the potential for supporting life outside the Earth. These include spacecraft and the following terrestrial laboratories: Biosphere 2 in Arizona, United States, 3.15 acres (13,000 m2). BIOS-1, BIOS-2 and BIOS-3 at the Institute of Biophysics in Krasnoyarsk, Siberia, in what was then the Soviet Union. Biosphere J (CEEF, Closed Ecology Experiment Facilities), an experiment in Japan. Micro-Ecological Life Support System Alternative (MELiSSA) at Autonomous University of Barcelona == Extraterrestrial biospheres == No biospheres have been detected beyond the Earth; therefore, the existence of extraterrestrial biospheres remains hypothetical. The rare Earth hypothesis suggests they should be very rare, save ones composed of microbial life only. On the other hand, Earth analogs may be quite numerous, at least in the Milky Way galaxy, given the large number of planets. Three of the planets discovered orbiting TRAPPIST-1 could possibly contain biospheres. Given limited understanding of abiogenesis, it is currently unknown what percentage of these planets actually develop biospheres. Based on observations by the Kepler Space Telescope team, it has been calculated that provided the probability of abiogenesis is higher than 1 to 1000, the closest alien biosphere should be within 100 light-years from the Earth. It is
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"page_id": 4816,
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also possible that artificial biospheres will be created in the future, for example with the terraforming of Mars. == See also == == References == == Further reading == The Biosphere (A Scientific American Book), San Francisco, W.H. Freeman and Co., 1970, ISBN 0-7167-0945-7. This book, originally the December 1970 Scientific American issue, covers virtually every major concern and concept since debated regarding materials and energy resources (including solar energy), population trends, and environmental degradation (including global warming). == External links == Article on the Biosphere at Encyclopedia of Earth GLOBIO.info, an ongoing programme to map the past, current and future impacts of human activities on the biosphere Paul Crutzen Interview, freeview video of Paul Crutzen Nobel Laureate for his work on decomposition of ozone talking to Harry Kroto Nobel Laureate by the Vega Science Trust. Atlas of the Biosphere
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"page_id": 4816,
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This is a list of books which talk about things related to current day physics or physics as it would be in the future. There a number of books that have been penned about specific physics concepts, e.g. quantum mechanics or kinematics, and many other books which discuss physics in general, i.e. not focussing on a single topic. There are also books that encourage beginners to enjoy physics by making them look at it from different angles. Capra, Fritjof (1999). The Tao of physics : an exploration of the parallels between modern physics and Eastern mysticism (4th, updated ed.). Boston: Shambhala. ISBN 1-57062-519-0. Chandrasekhar, S. (1958). An introduction to the study of stellar structure. [Republication]. New York: Dover. ISBN 978-0486604138. {{cite book}}: ISBN / Date incompatibility (help) Feynman, Richard P.; Leighton, Robert B.; Sands, Matthew (2009). The Feynman lectures on physics : the definitive and extended edition (2nd ed.). San Francisco, Calif.: Addison-Wesley. ISBN 978-0805390452. — (1997). "Surely You're Joking, Mr. Feynman!" : adventures of a curious character (1st Norton pbk. ed.). New York: W.W. Norton. ISBN 978-0393316049. Greene, Brian (2000). The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (1. Vintage Books ed.). New York: Vintage Books. ISBN 978-0375708114. — (2004). The fabric of the cosmos : space, time, and the texture of reality (1st Vintage Books ed.). New York: Vintage Books. ISBN 978-0375727207. — (2011). The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos (1st ed.). New York: Alfred A. Knopf. ISBN 978-0307265630. — (2008). Icarus at the Edge of Time (1st ed.). New York: Alfred A. Knopf. ISBN 978-0307268884. Gribbin, John (1984). In search of Schrödinger's cat : quantum physics and reality. Toronto: Bantam Books. ISBN 978-0553341034. — (1995). Schrödinger's kittens and the search for reality : solving the quantum
|
{
"page_id": 34738898,
"source": null,
"title": "List of books on popular physics concepts"
}
|
mysteries. Boston: Little, Brown & Co. ISBN 978-0316328197. Hawking, Stephen (1996). A Brief History of Time (Updated and expanded tenth anniversary ed.). New York: Bantam Books. ISBN 978-0553380163. — (2006). The theory of everything : the origin and fate of the universe (Special anniversary ed.). Mumbai: Jaico Pub. House. ISBN 978-8179925911. —; Mlodinow, Leonard (2008). A briefer history of time (Bantam trade pbk. ed.). New York: Bantam Books. ISBN 978-0553385465. —; Mlodinow, Leonard (2012). The grand design (2012 Bantam Books trade pbk. ed.). New York: Bantam Books. ISBN 978-0553384666. Kaku, Michio (1995). Hyperspace : a scientific odyssey through parallel universes, time warps, and the tenth dimension. illustrations by Robert O'Keefe (1st Anchor Books ed.). New York: Anchor Books. ISBN 978-0385477055. —; Thompson, Jennifer (1999). Beyond Einstein : the cosmic quest for the theory of the universe (Rev. and updated ed.). Oxford [England]: Oxford University Press. ISBN 978-0192861962. — (2006). Parallel worlds : a journey through creation, higher dimensions, and the future of the cosmos (1st Anchor Books ed.). New York: Anchor Books. ISBN 978-1400033720. — (2009). Physics of the impossible : a scientific exploration into the world of phasers, force fields, teleportation, and time travel (1st Anchor Books ed.). New York: Anchor Books. ISBN 978-0307278821. — (2012). Physics of the future : how science will shape human destiny and our daily lives by the year 2100 (1st Anchor Books ed.). New York: Anchor Books. ISBN 978-0307473332. Krauss, Lawrence M. A Universe from Nothing: Why There is Something Rather Than Nothing (1st Free Press hardcover ed.). New York: Free Press. ISBN 978-1-4516-2445-8. Kumar, Manjit (2009). Quantum : Einstein, Bohr, and the great debate about the nature of reality. Gurgaon: Hachette India. ISBN 978-93-80143-10-1. Lewin, Walter; Warren Goldstein. For the love of physics : from the end of the rainbow to the
|
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"page_id": 34738898,
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"title": "List of books on popular physics concepts"
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edge of time-- a journey through the wonders of physics (1st Free Press hardcover ed.). New York: Free Press. ISBN 1439108277. Talbot, Michael (1988). Beyond the quantum. Toronto: Bantam Books. ISBN 978-0553344806. — (1992). Mysticism and the new physics (Rev. and updated ed.). London: Arkana. ISBN 978-0140193282. Walker, Jearl (2007). The Flying Circus of Physics (2nd. ed.). Hoboken, NJ: Wiley. ISBN 978-0-471-76273-7.
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"page_id": 34738898,
"source": null,
"title": "List of books on popular physics concepts"
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Microtentacles are microtubule-based membrane protrusions that occur in detached cells. They were discovered by scientists studying metastatic breast cancer cells at the University of Maryland, Baltimore. These novel structures are distinct from classical actin based extensions of adherent cells, persist for days in breast tumor lines that are resistant to apoptosis, and aid in the reattachment to matrix or cell monolayers. The formation of microtentacles (McTNs) in detached or circulating tumor cells may promote seeding of bloodborne metastatic disease. == References == Yoon, JR; Whipple, RA; Balzer, EM; Cho, EH; Matrone, MA; Peckham, M; Martin, SS (Oct 2011). "Local anesthetics inhibit kinesin motility and microtentacle protrusions in human epithelial and breast tumor cells". Breast Cancer Res Treat. 129 (3): 691–701. doi:10.1007/s10549-010-1239-7. PMC 4232214. PMID 21069453. Balzer, EM; Whipple, RA; Thompson, K; Boggs, AE; Slovic, J; Cho, EH; Matrone, MA; Yoneda, T; Mueller, SC; Martin, SS (Dec 2010). "c-Src differentially regulates the functions of microtentacles and invadopodia". Oncogene. 29 (48): 6402–8. doi:10.1038/onc.2010.360. PMC 4073667. PMID 20956943. Matrone, MA; Whipple, RA; Balzer, EM; Martin, SS (Oct 2010). "Microtentacles tip the balance of cytoskeletal forces in circulating tumor cells". Cancer Res. 70 (20): 7737–41. doi:10.1158/0008-5472.CAN-10-1569. PMC 4232206. PMID 20924109. Whipple, RA; Matrone, MA; Cho, EH; Balzer, EM; Vitolo, MI; Yoon, JR; Ioffe, OB; Tuttle, KC; Yang, J; Martin, SS (Oct 2010). "Epithelial-to-mesenchymal transition promotes tubulin detyrosination and microtentacles that enhance endothelial engagement". Cancer Res. 70 (20): 8127–37. doi:10.1158/0008-5472.CAN-09-4613. PMC 3123454. PMID 20924103. Matrone, MA; Whipple, RA; Thompson, K; Cho, EH; Vitolo, MI; Balzer, EM; Yoon, JR; Ioffe, OB; Tuttle, KC; Tan, M; Martin, SS (Jun 2010). "Metastatic breast tumors express increased tau, which promotes microtentacle formation and the reattachment of detached breast tumor cells". Oncogene. 29 (22): 3217–27. doi:10.1038/onc.2010.68. PMC 3132415. PMID 20228842. Balzer, EM; Whipple, RA; Cho, EH; Matrone, MA; Martin, SS
|
{
"page_id": 19862229,
"source": null,
"title": "Microtentacle"
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(May 2010). "Antimitotic chemotherapeutics promote adhesive responses in detached and circulating tumor cells". Breast Cancer Res Treat. 121 (1): 65–78. doi:10.1007/s10549-009-0457-3. PMC 3633461. PMID 19593636. Whipple, R.A.; Balzer, E.M.; Cho, E.H; Matrone, M.A; Yoon, J.R.; Martin, S.S. (2008). "Vimentin Filaments Support Extension of Tubulin-Based Microtentacles in Detached Breast Tumor Cells". Cancer Research. 68 (14): 5678–5688. doi:10.1158/0008-5472.CAN-07-6589. PMC 2859318. PMID 18632620. Whipple, R.A.; Cheung, A.M.; Martin, S.S. (2007). "Detyrosinated microtubule protrusions in suspended mammary epithelial cells promote reattachment". Experimental Cell Research. 313 (7): 1326–36. doi:10.1016/j.yexcr.2007.02.001. PMC 3132414. PMID 17359970.
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{
"page_id": 19862229,
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"title": "Microtentacle"
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The mass excess of a nuclide is the difference between its actual mass and its mass number in daltons. It is one of the predominant methods for tabulating nuclear mass. The mass of an atomic nucleus is well approximated (less than 0.1% difference for most nuclides) by its mass number, which indicates that most of the mass of a nucleus arises from mass of its constituent protons and neutrons. Thus, the mass excess is an expression of the nuclear binding energy, relative to the binding energy per nucleon of carbon-12 (which defines the dalton). If the mass excess is negative, the nucleus has more binding energy than 12C, and vice versa. If a nucleus has a large excess of mass compared to a nearby nuclear species, it can radioactively decay, releasing energy. == Energy scale of nuclear reactions == The 12C standard provides a convenient unit (the dalton) in which to express nuclear mass for defining the mass excess. However, its usefulness arises in the calculation of nuclear reaction kinematics or decay. Only a small fraction of the total energy that is associated with an atomic nucleus by mass–energy equivalence, on the order of 0.01% to 0.1% of the total mass, may be absorbed or liberated as radiation. By working in terms of the mass excess, much of the mass changes which arise from the transfer or release of nucleons is effectively removed, highlighting the net energy difference. Nuclear reaction kinematics are customarily performed in units involving the electronvolt, which derives from accelerator technology. The combination of this practical point with the theoretical relation E = mc2 makes the unit megaelectronvolt over the speed of light squared (MeV/c2) a convenient form in which to express nuclear mass. However, the numerical values of nuclear masses in MeV/c2 are quite large (even
|
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"page_id": 8262357,
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"title": "Mass excess"
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the proton mass is ~938.27 MeV/c2), while mass excesses range in the tens of MeV/c2. This makes tabulated mass excess less cumbersome for use in calculations. The 1/c2 factor is typically omitted when quoting mass excess values in MeV, since the interest is more often energy and not mass; if one wanted units of mass, one would simply change the units from MeV to MeV/c2 without altering the numerical value. == Example == Consider the nuclear fission of 236U into 92Kr, 141Ba, and three neutrons. 236U → 92Kr + 141Ba + 3 n The mass number of the reactant, 236U, is 236. Because the actual mass is 236.045563 Da, its mass excess is +0.045563 Da. Calculated in the same manner, the respective mass excesses for the products, 92Kr, 141Ba, and three neutrons, are −0.073843 Da, −0.085588 Da and 3 × 0.008665 Da = +0.025994 Da, respectively, for a total mass excess of −0.133437 Da. The difference between the mass excess of the reactants and that of the products is 0.179000 Da, which shows that the mass excess of the products is less than that of the reactants, and so the fission can occur – a calculation which could have also been done with only the masses of the reactants. The mass excess can be converted into energy using 1 Da = 931.494 MeV/c2, and E = mc2, yielding 166.737 MeV. == References == Krane, K. S (1987). Introductory Nuclear Physics. John Wiley & Sons. ISBN 0-471-80553-X. Tipler, P. A; Llewellyn, R. A. (2004). Modern Physics. W. H. Freeman and Company. ISBN 0-7167-4345-0. == External links == Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
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{
"page_id": 8262357,
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"title": "Mass excess"
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James Douglas Morrison (1924–2013) was an Australian physical chemist. Born and educated in Glasgow (BSc 1945, PhD 1948), he moved to Australia in 1949 to work with the CSIRO. There he switched from X-ray crystallography to mass spectrometry as a research topic. In 1967 he was appointed as the foundation chair of physical chemistry at La Trobe University, where he was a professor of chemistry until retiring in 1989. He is known for his work in mass spectrometry and he is one of the inventors of the triple quadrupole mass spectrometer. == References ==
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{
"page_id": 52695769,
"source": null,
"title": "Jim Morrison (chemist)"
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Synthetic-aperture magnetometry (SAM) is a method for analysis of data obtained from magnetoencephalography (MEG) and electroencephalography (EEG). SAM is a nonlinear beamforming approach which can be thought of as a spatial filter. == See also == Aperture synthesis == References ==
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{
"page_id": 16257756,
"source": null,
"title": "Synthetic-aperture magnetometry"
}
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Ethnomycology is the study of the historical uses and sociological impact of fungi and can be considered a subfield of ethnobotany or ethnobiology. Although in theory the term includes fungi used for such purposes as tinder, medicine (medicinal mushrooms) and food (including yeast), it is often used in the context of the study of psychoactive mushrooms such as psilocybin mushrooms, the Amanita muscaria mushroom, and the ergot fungus. American banker Robert Gordon Wasson pioneered interest in this field of study in the late 1950s, when he and his wife became the first Westerners on record allowed to participate in a mushroom velada, held by the Mazatec curandera María Sabina. The biologist Richard Evans Schultes is also considered an ethnomycological pioneer. Later researchers in the field include Terence McKenna, Albert Hofmann, Ralph Metzner, Carl Ruck, Blaise Daniel Staples, Giorgio Samorini, Keewaydinoquay Peschel, John Marco Allegro, Clark Heinrich, John W. Allen, Jonathan Ott, Paul Stamets, Casey Brown and Juan Camilo Rodríguez Martínez. Besides mycological determination in the field, ethnomycology depends to a large extent on anthropology and philology. One of the major debates among ethnomycologists is Wasson's theory that the Soma mentioned in the Rigveda of the Indo-Aryans was the Amanita muscaria mushroom. Following his example similar attempts have been made to identify psychoactive mushroom usage in many other (mostly) ancient cultures, with varying degrees of credibility. Another much written about topic is the content of the Kykeon, the sacrament used during the Eleusinian mysteries in ancient Greece between approximately 1500 BCE and 396 CE. Although not an ethnomycologist as such, philologist John Allegro has made an important contribution suggesting, in a book controversial enough to have his academic career destroyed, that Amanita muscaria was not only consumed as a sacrament but was the main focus of worship in the more esoteric
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"page_id": 3674853,
"source": null,
"title": "Ethnomycology"
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sects of Sumerian religion, Judaism and early Christianity. Clark Heinrich claims that Amanita muscaria use in Europe was not completely wiped out by Orthodox Christianity but continued to be used (either consumed or merely symbolically) by individuals and small groups such as medieval Holy Grail myth makers, alchemists and Renaissance artists. While Wasson views historical mushroom use primarily as a facilitator for the shamanic or spiritual experiences core to these rites and traditions, McKenna takes this further, positing that the ingestion of psilocybin was perhaps primary in the formation of language and culture and identifying psychedelic mushrooms as the original "Tree of Knowledge". There is indeed some research supporting the theory that psilocybin ingestion temporarily increases neurochemical activity in the language centers of the brain, indicating a need for more research into the uses of psychoactive plants and fungi in human history. The 1990s saw a surge in the recreational use of psilocybin mushrooms due to a combination of a psychedelic revival in the rave culture, improved and simplified cultivation techniques, and the distribution of both the mushrooms themselves and information about them via the Internet. This "mushrooming of mushroom use" has also caused an increased popularization of ethnomycology itself as there are websites and Internet forums where mushroom references in Christmas and fairy tale symbolism are discussed. It remains open to interpretation what effect this popularization has on ethnomycology in the academic world, where the lack of verifiable evidence has kept its theories with their often far-reaching implications shrouded in controversy. == References == == Sources == Oswaldo Fidalgo, The ethnomycology of the Sanama Indians, Mycological Society of America (1976), ASIN B00072T1TC E. Barrie Kavasch, Alberto C. Meloni, American Indian EarthSense: Herbaria of Ethnobotany and Ethnomycology, Birdstone Press, the Institute for American Indian Studies (1996). ISBN 978-0-936322-05-6. Aaron Michael
|
{
"page_id": 3674853,
"source": null,
"title": "Ethnomycology"
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|
Lampman, Tzeltal ethnomycology: Naming, classification and use of mushrooms in the highlands of Chiapas, Mexico, Dissertation, ProQuest Information and Learning (2004) Jagjit Singh (ed.), From Ethnomycology to Fungal Biotechnology: Exploiting Fungi from Natural Resources for Novel Products, Springer (1999), ISBN 978-0-306-46059-3. Keewaydinoquay Peschel. Puhpohwee for the people: A narrative account of some use of fungi among the Ahnishinaubeg (Ethnomycological studies) Botanical Museum of Harvard University (1978),ASIN: B0006E6KTU == External links == "Aboriginal use of fungi", Australian National Botanic Gardens Fungi Web Site. https://web.archive.org/web/20070206142346/http://www.huh.harvard.edu/libraries/wasson.html R.G. Wasson] - Harvard University Herbaria https://web.archive.org/web/20070320151934/http://www.bu.edu/classics/faculty/profiles/ruck.html Carl A.P. Ruck] - Boston University Department of Classical Studies Albert Hofmann Foundation Terence McKenna - Official site John W. Allen - Official site John M. Allegro - Official site https://web.archive.org/web/20070127105105/http://www.gnosticmedia.com/main/ Jan Irvin and Andrew Rutajit] - Official site Dan Merkur - Official site Michael Hoffman Visionary Mushrooms Studies in Ethnomycology with Contributions by Gaston Guzman and Albert Hofmann
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{
"page_id": 3674853,
"source": null,
"title": "Ethnomycology"
}
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Noam Slonim (Hebrew: נעם סלונים; born in Jerusalem) is an Israeli computer scientist, specializing in Natural Language Processing and the application of Large language models. He is an IBM Distinguished Engineer, the founder and Principal Investigator of Project Debater, and serves as the Language Model Utilization lead at IBM Research. Beyond his scientific achievements, Slonim had a writing and media career. He was a writer for Season 4 of The Cameric Five TV comedy show, published a weekly column in Haaretz on brain science, and co-created and wrote the Israeli sitcom Puzzle. He was also the head writer for Seasons 2 and 3 of the sitcom Ha-movilim and featured in the 2020 documentary The Debater. == Education and research interests == Slonim graduated from the Hebrew University of Jerusalem in 1996 with a B.S. degree in Computer Science, Physics, and Mathematics. In 2002 he completed Ph.D. summa cum laude at the Interdisciplinary Center for Neural Computation at the Hebrew University, under the supervision of Professor Naftali Tishby. His thesis focused on the theory and applications of the Information Bottleneck method. From 2003 till 2006 he did post-doctoral studies at the Lewis-Sigler Institute for Integrative Genomics at Princeton University, working with Professor Bill Bialek and Professor Saeed Tavazoie. He joined IBM Research in 2007. Slonim holds over 30 patents (granted or pending) and has co-authored more than 100 scientific publications. == Research activities == From 1998 to 2003 he worked on the theory and applications of the Information Bottleneck method, suggesting various cluster analysis algorithms inspired by this method, and demonstrating the practical value of these algorithms on various domains. From 2003 to 2006 he worked on developing Machine Learning algorithms that rely on Information Theory concepts, and applied these algorithms to the analysis of various types of Genomics data. In
|
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"page_id": 68489959,
"source": null,
"title": "Noam Slonim"
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2011 he proposed to develop the first Artificial Intelligence system that can meaningfully participate in a full live debate with an expert human debater. This work gave rise to Project Debater, that debated expert human debaters in several live events during 2018 and 2019. In 2020, Slonim delivered the opening keynote at the EMNLP conference, describing the IBM Research work on developing Project Debater. Since 2022, Slonim has been leading IBM Research's efforts in applying large language models to practical use cases. == Writing and video career == In 1996 Slonim was a writer for Season 4 of The Cameric Five TV comedy show. In 1997–1998 he published a weekly column in Haaretz newspaper, focused on brain science research. In 1997–1999 he co-created and co-wrote the Israeli sitcom, Puzzle. In 2008–2010 he was the head writer of Season 2 and Season 3 of the Israeli Sitcom, Ha-movilim. In 2020 he was featured in the documentary The Debater, an official selection of the 2020 Copenhagen International Documentary Film Festival. == References ==
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{
"page_id": 68489959,
"source": null,
"title": "Noam Slonim"
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The Mycological Society of San Francisco (MSSF) is an amateur club based in the San Francisco Bay Area, "dedicated to promoting the understanding and enjoyment of fungi." Meetings are held every third Tuesday, and the society newsletter, Mycena News, is published once a month during the mushroom season, from September to May. == Activities == In addition to the general meetings, members hold numerous formal and informal fungi-hunting "forays" throughout the year. The Society also hosts an annual "Fungus Fair" aimed at educating the general public with mushroom displays, identification booths, and fungus-oriented activities. == Community == MSSF members often lend their expertise in mushroom identification to local authorities in possible poisoning cases. Since many of these occur to recent immigrants from countries with edible lookalikes, the Society has also produced a number of posters with pictures and warnings in multiple languages. In line with their goals of promoting the enjoyment of fungi, members often consult with land management organizations and work to maintain the rights of the general public to collect mushrooms for study and recreational purposes on public lands. == Membership == Membership is open to anyone interested in the study of fungi. Differing rates are offered for general membership, seniors, full-time students, and electronic members, who are not mailed the newsletter and instead download a PDF from the website. == References ==
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"page_id": 11604713,
"source": null,
"title": "Mycological Society of San Francisco"
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In physics, the n-body problem is the problem of predicting the individual motions of a group of celestial objects interacting with each other gravitationally. Solving this problem has been motivated by the desire to understand the motions of the Sun, Moon, planets, and visible stars. In the 20th century, understanding the dynamics of globular cluster star systems became an important n-body problem. The n-body problem in general relativity is considerably more difficult to solve due to additional factors like time and space distortions. The classical physical problem can be informally stated as the following: Given the quasi-steady orbital properties (instantaneous position, velocity and time) of a group of celestial bodies, predict their interactive forces; and consequently, predict their true orbital motions for all future times. The two-body problem has been completely solved and is discussed below, as well as the famous restricted three-body problem. == History == Knowing three orbital positions of a planet's orbit – positions obtained by Sir Isaac Newton from astronomer John Flamsteed – Newton was able to produce an equation by straightforward analytical geometry, to predict a planet's motion; i.e., to give its orbital properties: position, orbital diameter, period and orbital velocity. Having done so, he and others soon discovered over the course of a few years, those equations of motion did not predict some orbits correctly or even very well. Newton realized that this was because gravitational interactive forces amongst all the planets were affecting all their orbits. The aforementioned revelation strikes directly at the core of what the n-body issue physically is: as Newton understood, it is not enough to just provide the beginning location and velocity, or even three orbital positions, in order to establish a planet's actual orbit; one must also be aware of the gravitational interaction forces. Thus came the awareness
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and rise of the n-body "problem" in the early 17th century. These gravitational attractive forces do conform to Newton's laws of motion and to his law of universal gravitation, but the many multiple (n-body) interactions have historically made any exact solution intractable. Ironically, this conformity led to the wrong approach. After Newton's time the n-body problem historically was not stated correctly because it did not include a reference to those gravitational interactive forces. Newton does not say it directly but implies in his Principia the n-body problem is unsolvable because of those gravitational interactive forces. Newton said in his Principia, paragraph 21: And hence it is that the attractive force is found in both bodies. The Sun attracts Jupiter and the other planets, Jupiter attracts its satellites and similarly the satellites act on one another. And although the actions of each of a pair of planets on the other can be distinguished from each other and can be considered as two actions by which each attracts the other, yet inasmuch as they are between the same, two bodies they are not two but a simple operation between two termini. Two bodies can be drawn to each other by the contraction of rope between them. The cause of the action is twofold, namely the disposition of each of the two bodies; the action is likewise twofold, insofar as it is upon two bodies; but insofar as it is between two bodies it is single and one ... Newton concluded via his third law of motion that "according to this Law all bodies must attract each other." This last statement, which implies the existence of gravitational interactive forces, is key. As shown below, the problem also conforms to Jean Le Rond D'Alembert's non-Newtonian first and second Principles and to the nonlinear n-body
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problem algorithm, the latter allowing for a closed form solution for calculating those interactive forces. The problem of finding the general solution of the n-body problem was considered very important and challenging. Indeed, in the late 19th century King Oscar II of Sweden, advised by Gösta Mittag-Leffler, established a prize for anyone who could find the solution to the problem. The announcement was quite specific: Given a system of arbitrarily many mass points that attract each according to Newton's law, under the assumption that no two points ever collide, try to find a representation of the coordinates of each point as a series in a variable that is some known function of time and for all of whose values the series converges uniformly. In case the problem could not be solved, any other important contribution to classical mechanics would then be considered to be prizeworthy. The prize was awarded to Poincaré, even though he did not solve the original problem. (The first version of his contribution even contained a serious error.) The version finally printed contained many important ideas which led to the development of chaos theory. The problem as stated originally was finally solved by Karl Fritiof Sundman for n = 3 and generalized to n > 3 by L. K. Babadzanjanz and Qiudong Wang. == General formulation == The n-body problem considers n point masses mi, i = 1, 2, …, n in an inertial reference frame in three dimensional space ℝ3 moving under the influence of mutual gravitational attraction. Each mass mi has a position vector qi. Newton's second law says that mass times acceleration mi d2qi/dt2 is equal to the sum of the forces on the mass. Newton's law of gravity says that the gravitational force felt on mass mi by a single mass mj is
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given by F i j = G m i m j ‖ q j − q i ‖ 2 ⋅ ( q j − q i ) ‖ q j − q i ‖ = G m i m j ( q j − q i ) ‖ q j − q i ‖ 3 , {\displaystyle \mathbf {F} _{ij}={\frac {Gm_{i}m_{j}}{\left\|\mathbf {q} _{j}-\mathbf {q} _{i}\right\|^{2}}}\cdot {\frac {\left(\mathbf {q} _{j}-\mathbf {q} _{i}\right)}{\left\|\mathbf {q} _{j}-\mathbf {q} _{i}\right\|}}={\frac {Gm_{i}m_{j}\left(\mathbf {q} _{j}-\mathbf {q} _{i}\right)}{\left\|\mathbf {q} _{j}-\mathbf {q} _{i}\right\|^{3}}},} where G is the gravitational constant and ‖qj − qi‖ is the magnitude of the distance between qi and qj (metric induced by the l2 norm). Summing over all masses yields the n-body equations of motion:where U is the self-potential energy U = − ∑ 1 ≤ i < j ≤ n G m i m j ‖ q j − q i ‖ . {\displaystyle U=-\sum _{1\leq i<j\leq n}{\frac {Gm_{i}m_{j}}{\left\|\mathbf {q} _{j}-\mathbf {q} _{i}\right\|}}.} Defining the momentum to be pi = mi dqi/dt, Hamilton's equations of motion for the n-body problem become d q i d t = ∂ H ∂ p i d p i d t = − ∂ H ∂ q i , {\displaystyle {\frac {d\mathbf {q} _{i}}{dt}}={\frac {\partial H}{\partial \mathbf {p} _{i}}}\qquad {\frac {d\mathbf {p} _{i}}{dt}}=-{\frac {\partial H}{\partial \mathbf {q} _{i}}},} where the Hamiltonian function is H = T + U {\displaystyle H=T+U} and T is the kinetic energy T = ∑ i = 1 n ‖ p i ‖ 2 2 m i . {\displaystyle T=\sum _{i=1}^{n}{\frac {\left\|\mathbf {p} _{i}\right\|^{2}}{2m_{i}}}.} Hamilton's equations show that the n-body problem is a system of 6n first-order differential equations, with 6n initial conditions as 3n initial position coordinates and 3n initial momentum values. Symmetries in the n-body problem yield global integrals of motion that
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simplify the problem. Translational symmetry of the problem results in the center of mass C = ∑ i = 1 n m i q i ∑ i = 1 n m i {\displaystyle \mathbf {C} ={\frac {\displaystyle \sum _{i=1}^{n}m_{i}\mathbf {q} _{i}}{\displaystyle \sum _{i=1}^{n}m_{i}}}} moving with constant velocity, so that C = L0t + C0, where L0 is the linear velocity and C0 is the initial position. The constants of motion L0 and C0 represent six integrals of the motion. Rotational symmetry results in the total angular momentum being constant A = ∑ i = 1 n q i × p i , {\displaystyle \mathbf {A} =\sum _{i=1}^{n}\mathbf {q} _{i}\times \mathbf {p} _{i},} where × is the cross product. The three components of the total angular momentum A yield three more constants of the motion. The last general constant of the motion is given by the conservation of energy H. Hence, every n-body problem has ten integrals of motion. Because T and U are homogeneous functions of degree 2 and −1, respectively, the equations of motion have a scaling invariance: if qi(t) is a solution, then so is λ−2/3qi(λt) for any λ > 0. The moment of inertia of an n-body system is given by I = ∑ i = 1 n m i q i ⋅ q i = ∑ i = 1 n m i ‖ q i ‖ 2 {\displaystyle I=\sum _{i=1}^{n}m_{i}\mathbf {q} _{i}\cdot \mathbf {q} _{i}=\sum _{i=1}^{n}m_{i}\left\|\mathbf {q} _{i}\right\|^{2}} and the virial is given by Q = 1/2 dI/dt. Then the Lagrange–Jacobi formula states that d 2 I d t 2 = 2 T − U . {\displaystyle {\frac {d^{2}I}{dt^{2}}}=2T-U.} For systems in dynamic equilibrium, the longterm time average of ⟨d2I/dt2⟩ is zero. Then on average the total kinetic energy is half the total potential energy, ⟨T⟩
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= 1/2⟨U⟩, which is an example of the virial theorem for gravitational systems. If M is the total mass and R a characteristic size of the system (for example, the radius containing half the mass of the system), then the critical time for a system to settle down to a dynamic equilibrium is t c r = ( G M R 3 ) − 1 / 2 . {\displaystyle t_{\mathrm {cr} }=\left({\frac {GM}{R^{3}}}\right)^{-1/2}.} == Special cases == === Two-body problem === Any discussion of planetary interactive forces has always started historically with the two-body problem. The purpose of this section is to relate the real complexity in calculating any planetary forces. Note in this Section also, several subjects, such as gravity, barycenter, Kepler's Laws, etc.; and in the following Section too (Three-body problem) are discussed on other Wikipedia pages. Here though, these subjects are discussed from the perspective of the n-body problem. The two-body problem (n = 2) was completely solved by Johann Bernoulli (1667–1748) by classical theory (and not by Newton) by assuming the main point-mass was fixed; this is outlined here. Consider then the motion of two bodies, say the Sun and the Earth, with the Sun fixed, then: m 1 a 1 = G m 1 m 2 r 12 3 ( r 2 − r 1 ) Sun–Earth m 2 a 2 = G m 1 m 2 r 21 3 ( r 1 − r 2 ) Earth–Sun {\displaystyle {\begin{aligned}m_{1}\mathbf {a} _{1}&={\frac {Gm_{1}m_{2}}{r_{12}^{3}}}(\mathbf {r} _{2}-\mathbf {r} _{1})&&\quad {\text{Sun–Earth}}\\m_{2}\mathbf {a} _{2}&={\frac {Gm_{1}m_{2}}{r_{21}^{3}}}(\mathbf {r} _{1}-\mathbf {r} _{2})&&\quad {\text{Earth–Sun}}\end{aligned}}} The equation describing the motion of mass m2 relative to mass m1 is readily obtained from the differences between these two equations and after canceling common terms gives: α + η r 3 r = 0 {\displaystyle \mathbf {\alpha
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} +{\frac {\eta }{r^{3}}}\mathbf {r} =\mathbf {0} } Where r = r2 − r1 is the vector position of m2 relative to m1; α is the Eulerian acceleration d2r/dt2; η = G(m1 + m2). The equation α + η/r3r = 0 is the fundamental differential equation for the two-body problem Bernoulli solved in 1734. Notice for this approach forces have to be determined first, then the equation of motion resolved. This differential equation has elliptic, or parabolic or hyperbolic solutions. It is incorrect to think of m1 (the Sun) as fixed in space when applying Newton's law of universal gravitation, and to do so leads to erroneous results. The fixed point for two isolated gravitationally interacting bodies is their mutual barycenter, and this two-body problem can be solved exactly, such as using Jacobi coordinates relative to the barycenter. Dr. Clarence Cleminshaw calculated the approximate position of the Solar System's barycenter, a result achieved mainly by combining only the masses of Jupiter and the Sun. Science Program stated in reference to his work: The Sun contains 98 per cent of the mass in the solar system, with the superior planets beyond Mars accounting for most of the rest. On the average, the center of the mass of the Sun–Jupiter system, when the two most massive objects are considered alone, lies 462,000 miles from the Sun's center, or some 30,000 miles above the solar surface! Other large planets also influence the center of mass of the solar system, however. In 1951, for example, the systems' center of mass was not far from the Sun's center because Jupiter was on the opposite side from Saturn, Uranus and Neptune. In the late 1950s, when all four of these planets were on the same side of the Sun, the system's center of mass was more
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than 330,000 miles from the solar surface, Dr. C. H. Cleminshaw of Griffith Observatory in Los Angeles has calculated. The Sun wobbles as it rotates around the Galactic Center, dragging the Solar System and Earth along with it. What mathematician Kepler did in arriving at his three famous equations was curve-fit the apparent motions of the planets using Tycho Brahe's data, and not curve-fitting their true circular motions about the Sun (see figure). Both Robert Hooke and Newton were well aware that Newton's Law of Universal Gravitation did not hold for the forces associated with elliptical orbits. In fact, Newton's Universal Law does not account for the orbit of Mercury, the asteroid belt's gravitational behavior, or Saturn's rings. Newton stated (in section 11 of the Principia) that the main reason, however, for failing to predict the forces for elliptical orbits was that his math model was for a body confined to a situation that hardly existed in the real world, namely, the motions of bodies attracted toward an unmoving center. Some present physics and astronomy textbooks do not emphasize the negative significance of Newton's assumption and end up teaching that his mathematical model is in effect reality. It is to be understood that the classical two-body problem solution above is a mathematical idealization. See also Kepler's first law of planetary motion. === Three-body problem === This section relates a historically important n-body problem solution after simplifying assumptions were made. In the past not much was known about the n-body problem for n ≥ 3. The case n = 3 has been the most studied. Many earlier attempts to understand the three-body problem were quantitative, aiming at finding explicit solutions for special situations. In 1687, Isaac Newton published in the Principia the first steps in the study of the problem of
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the movements of three bodies subject to their mutual gravitational attractions, but his efforts resulted in verbal descriptions and geometrical sketches; see especially Book 1, Proposition 66 and its corollaries (Newton, 1687 and 1999 (transl.), see also Tisserand, 1894). In 1767, Euler found collinear motions, in which three bodies of any masses move proportionately along a fixed straight line. The Euler's three-body problem is the special case in which two of the bodies are fixed in space (this should not be confused with the circular restricted three-body problem, in which the two massive bodies describe a circular orbit and are only fixed in a synodic reference frame). In 1772, Lagrange discovered two classes of periodic solution, each for three bodies of any masses. In one class, the bodies lie on a rotating straight line. In the other class, the bodies lie at the vertices of a rotating equilateral triangle. In either case, the paths of the bodies will be conic sections. Those solutions led to the study of central configurations, for which q̈ = kq for some constant k > 0. A major study of the Earth–Moon–Sun system was undertaken by Charles-Eugène Delaunay, who published two volumes on the topic, each of 900 pages in length, in 1860 and 1867. Among many other accomplishments, the work already hints at chaos, and clearly demonstrates the problem of so-called "small denominators" in perturbation theory. In 1917, Forest Ray Moulton published his now classic, An Introduction to Celestial Mechanics (see references) with its plot of the restricted three-body problem solution (see figure below). An aside, see Meirovitch's book, pages 413–414 for his restricted three-body problem solution. Moulton's solution may be easier to visualize (and definitely easier to solve) if one considers the more massive body (such as the Sun) to be stationary in
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space, and the less massive body (such as Jupiter) to orbit around it, with the equilibrium points (Lagrangian points) maintaining the 60° spacing ahead of, and behind, the less massive body almost in its orbit (although in reality neither of the bodies are truly stationary, as they both orbit the center of mass of the whole system—about the barycenter). For sufficiently small mass ratio of the primaries, these triangular equilibrium points are stable, such that (nearly) massless particles will orbit about these points as they orbit around the larger primary (Sun). The five equilibrium points of the circular problem are known as the Lagrangian points. See figure below: In the restricted three-body problem math model figure above (after Moulton), the Lagrangian points L4 and L5 are where the Trojan planetoids resided (see Lagrangian point); m1 is the Sun and m2 is Jupiter. L2 is a point within the asteroid belt. It has to be realized for this model, this whole Sun-Jupiter diagram is rotating about its barycenter. The restricted three-body problem solution predicted the Trojan planetoids before they were first seen. The h-circles and closed loops echo the electromagnetic fluxes issued from the Sun and Jupiter. It is conjectured, contrary to Richard H. Batin's conjecture (see References), the two h1 are gravity sinks, in and where gravitational forces are zero, and the reason the Trojan planetoids are trapped there. The total amount of mass of the planetoids is unknown. The restricted three-body problem assumes the mass of one of the bodies is negligible. For a discussion of the case where the negligible body is a satellite of the body of lesser mass, see Hill sphere; for binary systems, see Roche lobe. Specific solutions to the three-body problem result in chaotic motion with no obvious sign of a repetitious path. The
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restricted problem (both circular and elliptical) was worked on extensively by many famous mathematicians and physicists, most notably by Poincaré at the end of the 19th century. Poincaré's work on the restricted three-body problem was the foundation of deterministic chaos theory. In the restricted problem, there exist five equilibrium points. Three are collinear with the masses (in the rotating frame) and are unstable. The remaining two are located on the third vertex of both equilateral triangles of which the two bodies are the first and second vertices. === Four-body problem === Inspired by the circular restricted three-body problem, the four-body problem can be greatly simplified by considering a smaller body to have a small mass compared to the other three massive bodies, which in turn are approximated to describe circular orbits. This is known as the bicircular restricted four-body problem (also known as bicircular model) and it can be traced back to 1960 in a NASA report written by Su-Shu Huang. This formulation has been highly relevant in the astrodynamics, mainly to model spacecraft trajectories in the Earth-Moon system with the addition of the gravitational attraction of the Sun. The former formulation of the bicircular restricted four-body problem can be problematic when modelling other systems than the Earth-Moon-Sun, so the formulation was generalized by Negri and Prado to expand the application range and improve the accuracy without loss of simplicity. === Planetary problem === The planetary problem is the n-body problem in the case that one of the masses is much larger than all the others. A prototypical example of a planetary problem is the Sun–Jupiter–Saturn system, where the mass of the Sun is about 1000 times larger than the masses of Jupiter or Saturn. An approximate solution to the problem is to decompose it into n − 1 pairs
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of star–planet Kepler problems, treating interactions among the planets as perturbations. Perturbative approximation works well as long as there are no orbital resonances in the system, that is none of the ratios of unperturbed Kepler frequencies is a rational number. Resonances appear as small denominators in the expansion. The existence of resonances and small denominators led to the important question of stability in the planetary problem: do planets, in nearly circular orbits around a star, remain in stable or bounded orbits over time? In 1963, Vladimir Arnold proved using KAM theory a kind of stability of the planetary problem: there exists a set of positive measure of quasiperiodic orbits in the case of the planetary problem restricted to the plane. In the KAM theory, chaotic planetary orbits would be bounded by quasiperiodic KAM tori. Arnold's result was extended to a more general theorem by Féjoz and Herman in 2004. === Central configurations === A central configuration q1(0), …, qN(0) is an initial configuration such that if the particles were all released with zero velocity, they would all collapse toward the center of mass C. Such a motion is called homothetic. Central configurations may also give rise to homographic motions in which all masses moves along Keplerian trajectories (elliptical, circular, parabolic, or hyperbolic), with all trajectories having the same eccentricity e. For elliptical trajectories, e = 1 corresponds to homothetic motion and e = 0 gives a relative equilibrium motion in which the configuration remains an isometry of the initial configuration, as if the configuration was a rigid body. Central configurations have played an important role in understanding the topology of invariant manifolds created by fixing the first integrals of a system. === n-body choreography === Solutions in which all masses move on the same curve without collisions are called choreographies.
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A choreography for n = 3 was discovered by Lagrange in 1772 in which three bodies are situated at the vertices of an equilateral triangle in the rotating frame. A figure eight choreography for n = 3 was found numerically by C. Moore in 1993 and generalized and proven by A. Chenciner and R. Montgomery in 2000. Since then, many other choreographies have been found for n ≥ 3. == Analytic approaches == For every solution of the problem, not only applying an isometry or a time shift but also a reversal of time (unlike in the case of friction) gives a solution as well. In the physical literature about the n-body problem (n ≥ 3), sometimes reference is made to "the impossibility of solving the n-body problem" (via employing the above approach). However, care must be taken when discussing the 'impossibility' of a solution, as this refers only to the method of first integrals (compare the theorems by Abel and Galois about the impossibility of solving algebraic equations of degree five or higher by means of formulas only involving roots). === Power series solution === One way of solving the classical n-body problem is "the n-body problem by Taylor series". We start by defining the system of differential equations: d 2 x i ( t ) d t 2 = G ∑ k = 1 k ≠ i n m k ( x k ( t ) − x i ( t ) ) | x k ( t ) − x i ( t ) | 3 , {\displaystyle {\frac {d^{2}\mathbf {x} _{i}(t)}{dt^{2}}}=G\sum _{k=1 \atop k\neq i}^{n}{\frac {m_{k}\left(\mathbf {x} _{k}(t)-\mathbf {x} _{i}(t)\right)}{\left|\mathbf {x} _{k}(t)-\mathbf {x} _{i}(t)\right|^{3}}},} As xi(t0) and dxi(t0)/dt are given as initial conditions, every d2xi(t)/dt2 is known. Differentiating d2xi(t)/dt2 results in d3xi(t)/dt3 which at t0 which
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is also known, and the Taylor series is constructed iteratively. === A generalized Sundman global solution === In order to generalize Sundman's result for the case n > 3 (or n = 3 and c = 0) one has to face two obstacles: As has been shown by Siegel, collisions which involve more than two bodies cannot be regularized analytically, hence Sundman's regularization cannot be generalized. The structure of singularities is more complicated in this case: other types of singularities may occur (see below). Lastly, Sundman's result was generalized to the case of n > 3 bodies by Qiudong Wang in the 1990s. Since the structure of singularities is more complicated, Wang had to leave out completely the questions of singularities. The central point of his approach is to transform, in an appropriate manner, the equations to a new system, such that the interval of existence for the solutions of this new system is [0,∞). === Singularities of the n-body problem === There can be two types of singularities of the n-body problem: collisions of two or more bodies, but for which q(t) (the bodies' positions) remains finite. (In this mathematical sense, a "collision" means that two pointlike bodies have identical positions in space.) singularities in which a collision does not occur, but q(t) does not remain finite. In this scenario, bodies diverge to infinity in a finite time, while at the same time tending towards zero separation (an imaginary collision occurs "at infinity"). The latter ones are called Painlevé's conjecture (no-collisions singularities). Their existence has been conjectured for n > 3 by Painlevé (see Painlevé conjecture). Examples of this behavior for n = 5 have been constructed by Xia and a heuristic model for n = 4 by Gerver. Donald G. Saari has shown that for 4 or fewer
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bodies, the set of initial data giving rise to singularities has measure zero. == Simulation == While there are analytic solutions available for the classical (i.e. nonrelativistic) two-body problem and for selected configurations with n > 2, in general n-body problems must be solved or simulated using numerical methods. === Few bodies === For a small number of bodies, an n-body problem can be solved using direct methods, also called particle–particle methods. These methods numerically integrate the differential equations of motion. Numerical integration for this problem can be a challenge for several reasons. First, the gravitational potential is singular; it goes to infinity as the distance between two particles goes to zero. The gravitational potential may be "softened" to remove the singularity at small distances: U ε = ∑ 1 ≤ i < j ≤ n G m i m j ‖ q j − q i ‖ 2 + ε 2 {\displaystyle U_{\varepsilon }=\sum _{1\leq i<j\leq n}{\frac {Gm_{i}m_{j}}{\sqrt {\left\|\mathbf {q} _{j}-\mathbf {q} _{i}\right\|^{2}+\varepsilon ^{2}}}}} Second, in general for n > 2, the n-body problem is chaotic, which means that even small errors in integration may grow exponentially in time. Third, a simulation may be over large stretches of model time (e.g. millions of years) and numerical errors accumulate as integration time increases. There are a number of techniques to reduce errors in numerical integration. Local coordinate systems are used to deal with widely differing scales in some problems, for example an Earth–Moon coordinate system in the context of a solar system simulation. Variational methods and perturbation theory can yield approximate analytic trajectories upon which the numerical integration can be a correction. The use of a symplectic integrator ensures that the simulation obeys Hamilton's equations to a high degree of accuracy and in particular that energy is conserved. === Many
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bodies === Direct methods using numerical integration require on the order of 1/2n2 computations to evaluate the potential energy over all pairs of particles, and thus have a time complexity of O(n2). For simulations with many particles, the O(n2) factor makes large-scale calculations especially time-consuming. A number of approximate methods have been developed that reduce the time complexity relative to direct methods: Tree code methods, such as a Barnes–Hut simulation, are spatially-hierarchical methods used when distant particle contributions do not need to be computed to high accuracy. The potential of a distant group of particles is computed using a multipole expansion or other approximation of the potential. This allows for a reduction in complexity to O(n log n). Fast multipole methods take advantage of the fact that the multipole-expanded forces from distant particles are similar for particles close to each other, and uses local expansions of far-field forces to reduce computational effort. It is claimed that this further approximation reduces the complexity to O(n). Particle mesh methods divide up simulation space into a three dimensional grid onto which the mass density of the particles is interpolated. Then calculating the potential becomes a matter of solving a Poisson equation on the grid, which can be computed in O(n log n) time using fast Fourier transform or O(n) time using multigrid techniques. This can provide fast solutions at the cost of higher error for short-range forces. Adaptive mesh refinement can be used to increase accuracy in regions with large numbers of particles. P3M and PM-tree methods are hybrid methods that use the particle mesh approximation for distant particles, but use more accurate methods for close particles (within a few grid intervals). P3M stands for particle–particle, particle–mesh and uses direct methods with softened potentials at close range. PM-tree methods instead use tree codes
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at close range. As with particle mesh methods, adaptive meshes can increase computational efficiency. Mean field methods approximate the system of particles with a time-dependent Boltzmann equation representing the mass density that is coupled to a self-consistent Poisson equation representing the potential. It is a type of smoothed-particle hydrodynamics approximation suitable for large systems. === Strong gravitation === In astrophysical systems with strong gravitational fields, such as those near the event horizon of a black hole, n-body simulations must take into account general relativity; such simulations are the domain of numerical relativity. Numerically simulating the Einstein field equations is extremely challenging and a parameterized post-Newtonian formalism (PPN), such as the Einstein–Infeld–Hoffmann equations, is used if possible. The two-body problem in general relativity is analytically solvable only for the Kepler problem, in which one mass is assumed to be much larger than the other. == Other n-body problems == Most work done on the n-body problem has been on the gravitational problem. But there exist other systems for which n-body mathematics and simulation techniques have proven useful. In large scale electrostatics problems, such as the simulation of proteins and cellular assemblies in structural biology, the Coulomb potential has the same form as the gravitational potential, except that charges may be positive or negative, leading to repulsive as well as attractive forces. Fast Coulomb solvers are the electrostatic counterpart to fast multipole method simulators. These are often used with periodic boundary conditions on the region simulated and Ewald summation techniques are used to speed up computations. In statistics and machine learning, some models have loss functions of a form similar to that of the gravitational potential: a sum of kernel functions over all pairs of objects, where the kernel function depends on the distance between the objects in parameter space. Example problems
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that fit into this form include all-nearest-neighbors in manifold learning, kernel density estimation, and kernel machines. Alternative optimizations to reduce the O(n2) time complexity to O(n) have been developed, such as dual tree algorithms, that have applicability to the gravitational n-body problem as well. A technique in Computational fluid dynamics called Vortex Methods sees the vorticity in a fluid domain discretized onto particles which are then advected with the velocity at their centers. Because the fluid velocity and vorticity are related via a Poisson's equation, the velocity can be solved in the same manner as gravitation and electrostatics: as an n-body summation over all vorticity-containing particles. The summation uses the Biot-Savart law, with vorticity taking the place of electrical current. In the context of particle-laden turbulent multiphase flows, determining an overall disturbance field generated by all particles is an n-body problem. If the particles translating within the flow are much smaller than the flow's Kolmogorov scale, their linear Stokes disturbance fields can be superposed, yielding a system of 3n equations for 3 components of disturbance velocities at the location of n particles. == See also == Celestial mechanics Gravitational two-body problem Jacobi integral Lunar theory Natural units Numerical model of the Solar System Stability of the Solar System Few-body systems N-body simulation, a method for numerically obtaining trajectories of bodies in an N-body system. == Notes == == References == == Further reading == == External links ==
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Since the first printing of Carl Linnaeus's Species Plantarum in 1753, plants have been assigned one epithet or name for their species and one name for their genus, a grouping of related species. Thousands of plants have been named for people, including botanists and their colleagues, plant collectors, horticulturists, explorers, rulers, politicians, clerics, doctors, philosophers and scientists. Even before Linnaeus, botanists such as Joseph Pitton de Tournefort, Charles Plumier and Pier Antonio Micheli were naming plants for people, sometimes in gratitude for the financial support of their patrons. Early works researching the naming of plant genera include an 1810 glossary by Alexandre de Théis and an etymological dictionary in two editions (1853 and 1856) by Georg Christian Wittstein. Modern works include The Gardener's Botanical by Ross Bayton, Index of Eponymic Plant Names and Encyclopedia of Eponymic Plant Names by Lotte Burkhardt, Plants of the World by Maarten J. M. Christenhusz (lead author), Michael F. Fay and Mark W. Chase, The A to Z of Plant Names by Allan J. Coombes, the four-volume CRC World Dictionary of Plant Names by Umberto Quattrocchi, and Stearn's Dictionary of Plant Names for Gardeners by William T. Stearn; these supply the seed-bearing genera listed in the first column below. Excluded from this list are genus names not accepted (as of January 2021) at Plants of the World Online, which includes updates to Plants of the World (2017). == Key == Ba = listed in Bayton's The Gardener's Botanical Bt = listed in Burkhardt's Encyclopedia of Eponymic Plant Names Bu = listed in Burkhardt's Index of Eponymic Plant Names Ch = listed in Christenhusz's Plants of the World Co = listed in Coombes's The A to Z of Plant Names Qu = listed in Quattrocchi's CRC World Dictionary of Plant Names St = listed in Stearn's
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"page_id": 66261739,
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"title": "List of plant genera named for people (Q–Z)"
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Dictionary of Plant Names for Gardeners In addition, Burkhardt's Index is used as a reference for every row in the table. == Genera == == See also == List of plant genus names with etymologies: A–C, D–K, L–P, Q–Z List of plant family names with etymologies == Notes == == Citations == == References == Bayton, Ross (2020). The Gardener's Botanical: An Encyclopedia of Latin Plant Names. Princeton, New Jersey: Princeton University Press. ISBN 978-0-691-20017-0. Burkhardt, Lotte (2018). Verzeichnis eponymischer Pflanzennamen – Erweiterte Edition [Index of Eponymic Plant Names – Extended Edition] (pdf) (in German). Berlin: Botanic Garden and Botanical Museum, Freie Universität Berlin. doi:10.3372/epolist2018. ISBN 978-3-946292-26-5. S2CID 187926901. Retrieved January 1, 2021. See http://creativecommons.org/licenses/by/4.0/ for license. Burkhardt, Lotte (2022). Eine Enzyklopädie zu eponymischen Pflanzennamen [Encyclopedia of eponymic plant names] (pdf) (in German). Berlin: Botanic Garden and Botanical Museum, Freie Universität Berlin. doi:10.3372/epolist2022. ISBN 978-3-946292-41-8. S2CID 246307410. Retrieved January 27, 2022. See http://creativecommons.org/licenses/by/4.0/ for license. Christenhusz, Maarten; Fay, Michael Francis; Chase, Mark Wayne (2017). Plants of the World: An Illustrated Encyclopedia of Vascular Plants. Chicago, Illinois: Kew Publishing and The University of Chicago Press. ISBN 978-0-226-52292-0. Coombes, Allen (2012). The A to Z of Plant Names: A Quick Reference Guide to 4000 Garden Plants. Portland, Oregon: Timber Press. ISBN 978-1-60469-196-2. Cullen, Katherine E. (2006). Biology: The People Behind the Science. New York, New York: Infobase Publishing. ISBN 978-0-8160-7221-7. POWO (2019). "Plants of the World Online". London: Royal Botanic Gardens, Kew. Archived from the original on March 22, 2017. Retrieved January 1, 2021. See http://www.plantsoftheworldonline.org/terms-and-conditions Archived 2021-04-23 at the Wayback Machine for license. Quattrocchi, Umberto (2019) [2000]. CRC World Dictionary of Plant Names, Volume IV, R–Z. Boca Raton, Florida: CRC Press. ISBN 978-0-367-44750-2. Stearn, William (2002). Stearn's Dictionary of Plant Names for Gardeners. London: Cassell. ISBN 978-0-304-36469-5. == Further reading ==
|
{
"page_id": 66261739,
"source": null,
"title": "List of plant genera named for people (Q–Z)"
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Gledhill, David (2008). The Names of Plants. New York, New York: Cambridge University Press. ISBN 978-0-521-86645-3.
|
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"page_id": 66261739,
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"title": "List of plant genera named for people (Q–Z)"
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Solar wind turbulence refers to the complex, chaotic fluid motions and magnetic field fluctuations observed in the solar wind plasma as it flows outward from the Sun. This turbulence plays a key role in heating the solar wind and accelerating charged particles throughout the heliosphere. Solar wind turbulence displays both magnetohydrodynamic (MHD) and kinetic plasma behaviors. It exhibits Kolmogorov-like power spectra at fluid scales, and shows strong Alfvénic correlations between velocity and magnetic field fluctuations, especially in fast solar wind. It evolves with distance from the Sun as the wind expands. The turbulence can be broadly categorized into: Large-scale Alfvénic fluctuations originating from the Sun Actively evolving turbulent cascade transferring energy to smaller scales Small-scale kinetic processes where the fluid approximation breaks down Observations from spacecraft like Helios, Ulysses, and Wind have revealed that solar wind turbulence properties vary between: Fast vs. slow solar wind streams Different heliographic latitudes Various distances from the Sun Current research focuses on the relative roles of waves vs. structures, evolution of turbulent properties with solar wind expansion, and kinetic processes at small scales where energy dissipates. == Further reading == Bruno, Roberto; Carbone, Vincenzo (2016). Turbulence in the solar wind. Switzerland: Springer. doi:10.1007/978-3-319-43440-7. ISBN 978-3-319-43439-1. == References ==
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{
"page_id": 78254826,
"source": null,
"title": "Solar wind turbulence"
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Freund's adjuvant is a solution of antigen emulsified in mineral oil and used as an immunopotentiator (booster). The complete form, Freund's Complete Adjuvant (FCA or CFA) is composed of inactivated and dried mycobacteria (usually M. tuberculosis), whereas the incomplete form (FIA or IFA) lacks the mycobacterial components (hence just the water in oil emulsion). It is named after Jules T. Freund. == Regulation == Freund's complete adjuvant is effective in stimulating cell-mediated immunity and leads to potentiation of T helper cells that leads to the production of certain immunoglobulins and effector T cells. Its use in humans is forbidden by regulatory authorities, due to its toxicity. In animal research there are also strict guidelines associated with its use, due to its potential for pain and tissue damage. Injections of FCA should be subcutaneous or intraperitoneal, because intradermal injections may cause skin ulceration and necrosis; intramuscular injections may lead to temporary or permanent muscle lesion, and intravenous injections may produce pulmonary lipid embolism. == Effects == When administered to diabetes prone non-obese diabetic (NOD) mice, Freund's complete adjuvant (FCA) prevented juvenile-onset diabetes. When combined with spleen cells, FCA was said to have reversed diabetes. In 2006, these claims were confirmed that even without spleen cells FCA can restore insulin producing beta cells in pancreas of NOD mice. Although newspapers have described the 2006 findings as confirming the earlier experiments, a report from NIH was released on November 23, 2006, in Science confirming the participation of spleen cells in reversing end-stage diabetes. It has also been investigated in an animal model of Parkinson's disease, or as well used in emulsion with Myelin oligodendrocyte glycoprotein (MOG), a peptide inducing Experimental autoimmune encephalomyelitis (EAE) in animal studies for efficacy testing of multiple sclerosis treatments. === Mechanism === FCA is known to stimulate production of
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"page_id": 30872302,
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"title": "Freund's adjuvant"
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tumor necrosis factor, which is thought to kill the T-cells responsible for the autoimmune destruction of the pancreatic beta cells. Still in question is whether the regrowth of functional insulin-producing cells occurs due to differentiation and proliferation of existing pancreatic stem cells, or whether the injected spleen cells re-differentiate to an insulin-producing form. Denise Faustman, whose work has been central to developing the protocol, has suggested that both mechanisms may play a role. However, in experiments to verify and examine her work, Suri reported that DNA-based evidence yielded no sign that spleen cells were needed in pancreatic islet beta cells regeneration after the FCA treatment. In pancreatic islets the β-cells regenerate following Freund's adjuvant treatment. This is related to the induction of Th17 cells by adjuvant treatment and these cells produce Interleukin-22 (IL-22). Pancreatic islets express high levels of IL-22 receptor and IL-22 has been shown to induce islet beta cell regeneration. == See also == Immunologic adjuvant == References == == External links == Recommendations for Use and Alternatives to Freund's Complete Adjuvant Archived 2012-02-27 at the Wayback Machine. University of Iowa
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"page_id": 30872302,
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"title": "Freund's adjuvant"
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In botany, blossoms are the flowers of stone fruit trees (genus Prunus) and of some other plants with a similar appearance that flower profusely for a period of time in spring. Colloquially, flowers of orange are referred to as such as well. Peach blossoms (including nectarine), most cherry blossoms, and some almond blossoms are usually pink. Plum blossoms, apple blossoms, orange blossoms, some cherry blossoms, and most almond blossoms are white. Blossoms provide pollen to pollinators such as bees, and initiate cross-pollination necessary for the trees to reproduce by producing fruit. == Herbal use == The ancient Phoenicians used almond blossoms with honey and urine as a tonic, and sprinkled them into stews and gruels to give muscular strength. Crushed petals were also used as a poultice on skin spots and mixed with banana oil, for dry skin and sunburn. In herbalism the crab apple was used as treatment for boils, abscesses, splinters, wounds, coughs, colds and a host of other ailments ranging from acne to kidney ailments. Many dishes made with apples and apple blossom are of medieval origin. In the spring, monks and physicians would gather the blossoms and preserve them in vinegar for drawing poultices and for bee stings and other insect bites. Descending from China and south east Asia, the earliest orange species moved westwards via the trade routes. In 17th century Italy peach blossoms were made into a poultice for bruises, rashes, eczema, grazes and stings. In ancient Greek medicine plum blossoms were used to treat bleeding gums, mouth ulcers and tighten loose teeth. Plum blossoms mixed with sage leaves and flowers were used in plum wine or plum brandy as a mouthwash to soothe sore throats and mouth ailments and sweeten bad breath. == Blossom festivals == Hanami (花見, "flower viewing") is the Japanese
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"page_id": 70382,
"source": null,
"title": "Blossom"
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traditional custom of enjoying the transient beauty of flowers; in this case almost always refer to those of the cherry (桜, sakura) or, less frequently, plum (梅, ume) trees. In England, Wales and Northern Ireland the National Trust organises the environmental awareness campaign #BlossomWatch, which is designed to raise awareness of the first signs of Spring, by encouraging people to share images of blossoms via social media. == Gallery == == See also == Fragrance extraction == References == == External links == Blossom in other languages. Millais, John Everett. Apple blossoms. Lady Lever Art Gallery. "In Pictures: Your blossoming spring". BBC Nature.
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{
"page_id": 70382,
"source": null,
"title": "Blossom"
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Pimascovirales is an order of viruses. The term is a portmanteau of a portmanteau of pitho-, irido-, marseille-, and ascoviruses. == Families == Pimascovirales contains six families, three of which are assigned to a suborder. This taxonomy is shown hereafter: Suborder: Ocovirineae Hydriviridae Orpheoviridae Pithoviridae Families not assigned to a suborder: Ascoviridae Iridoviridae Marseilleviridae == References ==
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"page_id": 63771377,
"source": null,
"title": "Pimascovirales"
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Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacteria inside these organisms. While there exist a wide range of peptides that are not synthesized by ribosomes, the term nonribosomal peptide typically refers to a very specific set of these as discussed in this article. Nonribosomal peptides are synthesized by nonribosomal peptide synthetases, which, unlike the ribosomes, are independent of messenger RNA. Each nonribosomal peptide synthetase can synthesize only one type of peptide. Nonribosomal peptides often have cyclic and/or branched structures, can contain non-proteinogenic amino acids including D-amino acids, carry modifications like N-methyl and N-formyl groups, or are glycosylated, acylated, halogenated, or hydroxylated. Cyclization of amino acids against the peptide "backbone" is often performed, resulting in oxazolines and thiazolines; these can be further oxidized or reduced. On occasion, dehydration is performed on serines, resulting in dehydroalanine. This is just a sampling of the various manipulations and variations that nonribosomal peptides can perform. Nonribosomal peptides are often dimers or trimers of identical sequences chained together or cyclized, or even branched. Nonribosomal peptides are a very diverse family of natural products with an extremely broad range of biological activities and pharmacological properties. They are often toxins, siderophores, or pigments. Nonribosomal peptide antibiotics, cytostatics, and immunosuppressants are in commercial use. == Examples == == Biosynthesis == Nonribosomal peptides are synthesized by one or more specialized nonribosomal peptide-synthetase (NRPS) enzymes. The NRPS genes for a certain peptide are usually organized in one operon in bacteria and in gene clusters in eukaryotes. However the first fungal NRP to be found was ciclosporin. It is synthesized by a single 1.6MDa NRPS. The enzymes are organized in modules that are
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"page_id": 1118963,
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"title": "Nonribosomal peptide"
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responsible for the introduction of one additional amino acid. Each module consists of several domains with defined functions, separated by short spacer regions of about 15 amino acids. The biosynthesis of nonribosomal peptides shares characteristics with the polyketide and fatty acid biosynthesis. Due to these structural and mechanistic similarities, some nonribosomal peptide synthetases contain polyketide synthase modules for the insertion of acetate or propionate-derived subunits into the peptide chain. Note that as many as 10% percent of bacterial NRPS are not laid out as large modular proteins, but as separate enzymes. Some NRPS modules deviate from the standard domain structure, and some extra domains have been described. There are also NRPS enzymes that serve as a scaffold for other modifications to the substrate to incorporate unusual amino acids. === Modules === The order of modules and domains of a complete nonribosomal peptide synthetase is as follows: Initiation or Starting module: [F/NMT]-A-PCP- Elongation or Extending modules: -(C/Cy)-[NMT]-A-PCP-[E]- Termination or Releasing module: -(TE/R) (Order: N-terminus to C-terminus; []: optionally; (): alternatively) === Domains === F: Formylation (optional) A: Adenylation (required in a module) PCP: Thiolation and peptide carrier protein with attached 4'-phospho-pantetheine (required in a module) C: Condensation forming the amide bond (required in a module) Cy: Cyclization into thiazoline or oxazolines (optional) Ox: Oxidation of thiazolines or oxazolines to thiazoles or oxazoles (optional) Red: Reduction of thiazolines or oxazolines to thiazolidines or oxazolidines (optional) E: Epimerization into D-amino acids (optional) NMT: N-methylation (optional) TE: Termination by a thio-esterase (only found once in a NRPS) R: Reduction to terminal aldehyde or alcohol (optional) X: Recruits cytochrome P450 enzymes (optional) === Starting stage === Loading: The first amino acid is activated with ATP as a mixed acyl-phosphoric acid anhydride with AMP by the A-domain and loaded onto the serine-attached 4'-phospho-pantethine (4'PP) sidechain of
|
{
"page_id": 1118963,
"source": null,
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the PCP-domain catalyzed by the PCP-domain (thiolation). Some A domains require interaction with MbtH-like proteins for their activity. Sometimes the amino group of the bound amino acid is formylated by an F-domain or methylated by an NMT-domain. === Elongation stages === Loading: Analogous to the starting stage, each module loads its specific amino acid onto its PCP-domain. Condensation: The C-domain catalyzes the amide bond formation between the thioester group of the growing peptide chain from the previous module with the amino group of the current module. The extended peptide is now attached to the current PCP-domain. Condensation-Cyclization: Sometimes the C-domain is replaced by a Cy-domain, which, in addition to the amide bond formation, catalyzes the reaction of the serine, threonine, or cysteine sidechain with the amide-N, thereby forming oxazolidines and thiazolidine, respectively. Epimerization: Sometimes an E-domain epimerizes the innermost amino acid of the peptide chain into the D-configuration. This cycle is repeated for each elongation module. === Termination stage === Termination: The TE-domain (thio-esterase domain) hydrolyzes the completed polypeptide chain from the PCP-domain of the previous module, thereby often forming cyclic amides (lactams) or cyclic esters (lactones). Also, the peptide can be released by an R-domain that reduces the thioester bond to terminal aldehyde or alcohol. === Processing === The final peptide is often modified, e.g., by glycosylation, acylation, halogenation, or hydroxylation. The responsible enzymes are usually associated to the synthetase complex and their genes are organized in the same operons or gene clusters. === Priming and deblocking === To become functional, the 4'-phospho-pantetheine sidechain of acyl-CoA molecules has to be attached to the PCP-domain by 4'PP transferases (Priming) and the S-attached acyl group has to be removed by specialized associated thioesterases (TE-II) (Deblocking). === Substrate specificities === Most domains have a very broad substrate specificity and usually only the
|
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A-domain determines which amino acid is incorporated in a module. Ten amino acids that control substrate specificity and can be considered the 'codons' of nonribosomal peptide synthesis have been identified, and rational protein design has yielded methodologies to computationally switch the specificities of A-domains. The condensation C-domain is also believed to have substrate specificity, especially if located behind an epimerase E-domain-containing module where it functions as a 'filter' for the epimerized isomer. Computational methods, such as SANDPUMA and NRPSpredictor2, have been developed to predict substrate specificity from DNA or protein sequence data. === Mixed with polyketides === Due to the similarity with polyketide synthases (PKS), many secondary metabolites are, in fact, fusions of NRPs and polyketides. In essence, this occurs when PK modules follow NRP modules, and vice versa. Although there is high degree of similarity between the Carrier (PCP/ACP) domains of both types of synthetases, the mechanism of condensation is different from a chemical standpoint: PKS, carbon-carbon bond formation through Claisen condensation reaction NRPs, the C domain catalyzes the amide bond formation between the amino acid it adds to the chain (on the PCP of one module) and the nascent peptide(on the PCP of the next module). == See also == Epothilone Esterase Ribosomally synthesized and post-translationally modified peptides == References == == Further reading ==
|
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"page_id": 1118963,
"source": null,
"title": "Nonribosomal peptide"
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Clumping is a behavior in an organism, usually sessile, in which individuals of a particular species group close to one another for beneficial purposes. Clumping can be caused by the abiotic environment surrounding an organism. Barnacles, for example, group together on rocks that are exposed for the least amount of time during the low tide. Usually, clumping in sessile animals starts when one organism binds to a hard substrate, such as rock, and other members of the same species attach themselves afterwards. Herbivorous snails are known to clump around where sufficient algae are present. The clumping of mussels (shown right) has been found to be influenced by competition with other species. The mussels attach themselves by byssal threads to potential competitors for space. == Causes == === Predation avoidance === Clumping and increased locomotion has been found to occur with organisms such as blue mussels (Mytilus edulis) due to risks from predators such as the European lobster (Homarus gammarus). Trade-offs exist with clumping such as decreased growth and less reproductive activity from mussels clumping together due to predation. However, there are also benefits obtained, such as decreased mortality from predation and adverse weather conditions, from clumping. Clumping has been practiced by bivalve organisms from the times of the fossil record, and the trade-offs between living quite an aggregated lifestyle. Predators such as the gastropod Nucella lamellosa utilize drilling techniques in order to hunt prey such as the blue mussels, and the latter's clumping strategies results in significantly less drilling frequency overall. However, the average drilling placement and variation by the gastropod did not show variation as a result of clumping. == Measurement == Measuring clumped populations of organisms in nature can prove challenging at times for researchers. Quadrat sampling, a favored method by ecologists to study the density of populations,
|
{
"page_id": 660213,
"source": null,
"title": "Clumping (biology)"
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|
is not as effective with criteria such as those groups that are clumped. Other methods instead can be utilized to measure clumped populations, such as the line-intercept method which is more popular with organisms that can be studied and identified before they move. The reasoning behind organisms clumping revolve around resources being restrained in smaller regions within larger ones and select organisms forming social groups. The funnel-web spider (Agelenopsis aperta) at smaller scales are evenly distributed in their habitats, but are a clumped species on larger scales. The reasoning for this is two-fold. Firstly, these types of spiders prefer environments with the ability to attract insect prey and have favorable thermal properties. Secondly, there is a limited space for spiders to establish their websites, and competition for these spaces is substantial. However, on a macro scale, most organisms actually have clumped distributions due to their habitats not being eventually distributed over extensive areas. Similar trends are seen with other species of spiders. Stegodyphus lineatus sees disadvantages no matter what other parameters exist when feeding in large groups. Otherwise, these types of spiders were able to survive in close proximity most effectively when they were of approximate equal size. The size of groups also played a role in the ability of these spiders to live. == Cellular clumping == The practice of clumping occurs at both the macro and micro level for organisms. Closely tied to the endosymbiotic theory, there exists significant evidence that single-celled organisms in the distant past evolved and combined with other organisms to create complex multi-cellular lifeforms that make up much of life in the present. This was despite the fact that these single-celled organisms were capable of sustaining themselves and reproducing to create future generations. Nevertheless, this occurrence is considered to be a major transition in
|
{
"page_id": 660213,
"source": null,
"title": "Clumping (biology)"
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the evolution of life. The benefits of these multi-cellular lifeforms forming include further advances in efficiency to already existing ways that single-celled organisms cooperated; the creation of extracellular "public goods" is an example of organisms gaining from clumping. However, cooperation could still evolve and coexist alongside clumping as a strategy for organisms. As genetic similarity strengthened between organisms that clumped, both "public goods" production and clumping itself became more prevalent and easier to accomplish in the case of the latter. In addition, just small changes in genetic similarity can cause major shifts the outcome of evolution for organisms, such as increased output of vital materials for survival and growth. Clumping can be impeded when the number of organisms that benefits must be shared with increases, but stimulated when those organisms are more related to one another. == References ==
|
{
"page_id": 660213,
"source": null,
"title": "Clumping (biology)"
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Extrusion in food processing consists of forcing soft mixed ingredients through an opening in a perforated plate or die designed to produce the required shape. The extruded food is then cut to a specific size by blades. The machine which forces the mix through the die is an extruder, and the mix is known as the extrudate. The extruder is typically a large, rotating screw tightly fitting within a stationary barrel, at the end of which is the die. In some cases, "extrusion" is taken as synonymous with extrusion cooking, which cooks the food with heat as it is squeezed through the die. Extrusion enables mass production of food via a continuous, efficient system that ensures uniformity of the final product. Products made through extrusion (without simultaneous cooking) include pasta, breads (croutons, bread sticks, and flat breads), pre-made cookie dough, and sausages. Products made through extrusion cooking include many breakfast cereals and ready-to-eat snacks, confectionery, some baby foods, full-fat soy flour, textured vegetable protein, some beverages, and dry and semi-moist pet foods. Food products manufactured using extrusion usually have a high starch content. == Process == === Extrusion cooking === In the extrusion cooking process, raw materials are first ground to the correct particle size, usually the consistency of coarse flour. The dry mix is passed through a pre-conditioner, in which other ingredients are added depending on the target product; these may be liquid sugar, fats, dyes, meats or water. Steam is injected to start the cooking process, and the preconditioned mix (extrudate) is then passed through an extruder. The extruder is a large, rotating screw tightly fitting within a stationary barrel, at the end of which is the die. The extruder's rotating screw forces the extrudate towards and through the die. The extrudate is in the extruder for the
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{
"page_id": 36442869,
"source": null,
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residence time. Many extruded products puff and change texture as they are extruded because of the reduction of forces and release of moisture and heat. The extent to which it does so is known as the expansion ratio. The extrudate is cut to the desired length by blades at the output of the extruder, which rotate about the die openings at a specific speed. The product is then cooled and dried, becoming rigid while maintaining porosity. Cooking takes place within the extruder, where the product produces its own friction and heat due to the pressure generated (10–20 bar). The process can induce both protein denaturation and starch gelatinization under some conditions. Many food extrusion processes involve a high temperature for a short time. Important factors of the extrusion process are the composition of the extrudate, screw length and rotating speed, barrel temperature and moisture, die shape, and rotating speed of the blades. These are controlled based on the desired product to ensure uniformity of the output. Moisture is the most important of these factors, and affects the mix viscosity, acting to plasticize the extrudate. Increasing moisture will decrease viscosity, torque, and product temperature, and increase bulk density. This will also reduce the pressure at the die. Most extrusion processes for food processing are carried out at low to intermediate moisture (moisture level below 40%). High-moisture extrusion is known as wet extrusion, but it was not used much before the introduction of twin screw extruders (TSE), which have a more efficient conveying capability. The most important rheological factor in the wet extrusion of high-starch extrudate is temperature. The amount of salt in the extrudate may determine the colour and texture of some extruded products. The expansion ratio and airiness of the product depend on the salt concentration in the extrudate, possibly
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{
"page_id": 36442869,
"source": null,
"title": "Food extrusion"
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as a result of a chemical reaction between the salt and the starches in the extrudate. Colour changes as a result of salt concentration may be caused by "the ability of salt to change the water activity of the extrudate and thus change the rate of browning reactions". Salt is also used to distribute minor ingredients, such as food colours and flavours, after extrusion; these are more evenly distributed over the product's surface after being mixed with salt. == History == The first extruder was designed to manufacture sausages in the 1870s. Dry pasta has been produced by extrusion since the 1930s, and the method has been applied to tater tots (first extruded potato product: Ore-Ida in 1953). Some domestic kitchen appliances such as meat grinders and some types of pasta makers use extrusion. Pastry bags (piping bags), squeezed by hand, operate by extrusion. The first extrusion cooking machine was the expanding pelleting machine from Wenger Mixer Manufacturing from 1954. Its first mentioned use seems to be with Purina in 1957, which developed extruded food for dogs, monkeys, and fish. In 1963, the USDA and UNICEF tested a full fat soy flour produced from extrusion-cooked soybeans as a source of nutrients for children. Milk substitutes were later developed from this flour. In 1966, the US government started providing a CSM (Corn-Soya-Milk) formula to protein-deficient children in the Third World. The later Meals for Millions project also prominently featured soy flour in its Multi-Purpose Food (MPF), a high-protein food supplement that could be made for just three cents per meal. The idea of using extrusion cooking to produce breakfast cereal has been mentioned since the Wegner patent of 1960. In 1970, the Israeli Shefa Protein Industries introduced a line of breakfast cereal called Krunch, made from cereal flour and full-fat soy
|
{
"page_id": 36442869,
"source": null,
"title": "Food extrusion"
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flour. It's unclear whether there has been an earlier breakfast cereal made from extruded products. Meat analogues have been made through extrusion since 1969. == Effects == Extrusion enables mass production of food via a continuous, efficient system that ensures uniformity of the final product. This is achieved by controlling various aspects of the extrusion process. It has also enabled the production of new processed food products and "revolutionized many conventional snack manufacturing processes". === Chemical changes with cooking === Extrusion cooking results in "chemical reactions that occur within the extruder barrel and at the die" like most other forms of cooking. Extrusion enables mass production of some food, and will "denature antinutritional factors" while destroying toxins or killing microorganisms. It may also improve protein quality and digestibility and affects the product's shape, texture, colour, and flavour. Changes associated with extrusion include: Destruction of certain naturally occurring toxins and antinutrients (including trypsin inhibitors, haemagglutinins, tannins and phytates) All four listed antinutrients reduce the absorption of protein. Phytate and tannins also reduce the absorption of minerals. Reduction in the level of microorganisms in the final product. Partial destruction of heat-liable vitamins (A, B, C, and E). Moderate increase in protein digestibility, due to protein protein denaturation and the inactivation of antinutrients. Maillard reactions, which reduce the available amounts of certain amino acids, including the essential amino acid lysine. Lysine loss can be reduced by using wetter mixtures. Breakdown of complex carbohydrates (starches and non-starch polysaccharides) into simpler components. Part of this action is caused by amylase from the cereal themselves. This increases glycemic index and creates starches more likely to cause and insulin resistance. The "extrusion process significantly increased the availability of carbohydrates for digestion". This may also lead to higher tooth decay. On the other hand, this breakdown converts insoluble
|
{
"page_id": 36442869,
"source": null,
"title": "Food extrusion"
}
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fibers into soluble fibers. Binding and volatization of flavor compounds. Gelatinization of starch. An increase in iron content due to the wearing of machine components. No significant change in zinc absorption. As of 1998, little is known about the stability or bioavailability of phytochemicals involved in extrusion. Phenols appear to be decreased. Overall, the effects of "extrusion cooking on nutritional quality are ambiguous", as extrusion may change carbohydrates, dietary fibre, the protein and amino acid profile, vitamins, and mineral content of the extrudate in a manner that is beneficial or harmful. Nutritional quality has been found to improve with moderate conditions (short duration, high moisture, low temperature), whereas a negative effect on nutritional quality of the extrudate occurs with a high temperature (at least 200 °C), low moisture (less than 15%), or improper components in the mix. High-temperature extrusion for a short duration "minimizes losses in vitamins and amino acids". A 2012 research paper indicates that use of non-traditional cereal flours, such as amaranth, buckwheat or millet, may be used to reduce the glycemic index of breakfast cereals produced by extrusion. The extrudate using these cereal flours exhibits a higher bulk and product density, has a similar expansion ratio, and has "a significant reduction in readily digestible carbohydrates and slowly digestible carbohydrates". A 2008 paper states that replacing 5% to 15% of the wheat flour and white flour with dietary fibre in the extrudate breakfast cereal mix significantly reduces "the rate and extent of carbohydrate hydrolysis of the extruded products", which increased the level of slowly digested carbohydrates and reduced the level of quickly digested carbohydrates. === Texture === The material of which an extrusion die is made can affect the final product. Rough bronze dies on pasta extruders produce a rougher surface than smooth stainless steel dies, considered to
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"title": "Food extrusion"
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make more liquid pasta sauces adhere better; pasta made this way is labelled "bronze die" pasta to indicate a premium product. Pasta dies == Products == Extrusion has enabled the production of new processed food products and "revolutionized many conventional snack manufacturing processes". The various types of food products manufactured by extrusion typically have a high starch content. Directly expanded types include breakfast cereals and corn curls, and are made in high-temperature, low-moisture conditions under high shear. Unexpanded products include pasta, which is produced at intermediate moisture (about 40%) and low temperature. Texturized products include meat analogues, which are made using plant proteins ("textured vegetable protein") and a long die to "impart a fibrous, meat-like structure to the extrudate", and fish paste. Some processed cheeses and cheese analogues are also made by extrusion. Processed cheeses extruded with low moisture and temperature "might be better suited for manufacturing using extrusion technology" than those at high moisture or temperature. Lower moisture cheeses are firmer and chewier, and cheddar cheese with low moisture and an extrusion temperature of 80 °C was preferred by subjects in a study to other extruded cheddar cheese produced under different conditions. An extrudate mean residence time of about 100 seconds can produce "processed cheeses or cheese analogues of varying texture (spreadable to sliceable)". Confectionery made via extrusion includes chewing gum, liquorice, and toffee. Other food products often produced by extrusion include some breads (croutons, bread sticks, and flat breads), various ready-to-eat snacks, pre-made cookie dough, some baby foods, some beverages, and dry and semi-moist pet foods. Specific examples include cheese curls, macaroni, Fig Newtons, jelly beans, sevai, and some french fries. Extrusion is also used to modify starch and to pellet animal feed. == See also == Flash pasteurization == References == == Further reading == Edwin van
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{
"page_id": 36442869,
"source": null,
"title": "Food extrusion"
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|
Onna; Brigitte van Mechelen; Matthew Stewart; Shonquis Moreno; Chris Scott; Sarah Martin Pearson; Joeri Bruyninckx; Masaaki Takahashi (1993). The technology of Extrusion Cooking. Springer. ISBN 9780834213401. Guy, R. C. E. (2003). "EXTRUSION COOKING/Principles and Practice". Encyclopedia of Food Sciences and Nutrition. pp. 2222–2227. doi:10.1016/B0-12-227055-X/00434-X. ISBN 9780122270550.
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{
"page_id": 36442869,
"source": null,
"title": "Food extrusion"
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Paleodictyon is a trace fossil, usually interpreted to be a burrow, which appears in the geologic marine record beginning in the Precambrian/Early Cambrian and in modern ocean environments. Paleodictyon were first described by Giuseppe Meneghini in 1850. The origin of the trace fossil is enigmatic and numerous candidates have been proposed. == Description == Paleodictyon consist of thin tunnels or ridges that usually form hexagonal or polygonal-shaped honeycomb-like network. Both irregular and regular nets are known throughout the stratigraphic range of Paleodictyon, but it is the striking regular honeycomb pattern of some forms such as P. carpathecum and P. nodosum which make it notable and widely studied. Individual mesh elements may be millimeters to centimeters, usually from 1-1.5 to 2-3 cm, and entire mesh patterns can cover areas up to a square meter. The edges or threads that make up the mesh are usually cylindrical or ellipsoid in cross-section, and some forms have vertical tubes connecting the mesh upwards to the sediment-water interface. Dolf Seilacher proposed in 1977 that it may be a trap for food, a mechanism for farming, or a foraging path. Alternatively, it has been suggested that it may be a cast of a xenophyophoran protist. Mark McMenamin proposed that Paleodictyon represents a microburrow nest structure. The nest structure empties once the juveniles mature and disperse. == History of study == Much modeling work has been done on Paleodictyon. Roy Plotnick, trace fossil researcher at University of Illinois at Chicago, modeled the form as resulting from the iterative modular growth of an unknown organism. Garlick and Miller modeled it as a burrow with a relatively simple burrow algorithm. == Hypotheses about origin == The question is whether these patterns are burrows of marine animals such as worms or fossilized remains of ancient organisms (sponges or algae). Observations
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"page_id": 13308663,
"source": null,
"title": "Paleodictyon"
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|
on Paleodictyon using Euler graph theory suggest that it is unlikely to be an excavation trace fossil, and that it is more likely to be an imprint or body fossil, or to be of abiotic origin. It has been suggested that Paleodictyon may represent a body fossil of a xenophyophore, a type of giant foraminifera. The infaunal xenophyophore Occultammina does bear some physical resemblance to Paleodictyon and the abyssal habitat of modern xenophyophores is indeed similar to the inferred paleoenvironment where fossil graphoglyptids are found; however, the large size (up to 0.5 m) and regularity of many graphoglyptids as well as the apparent absence of collected sediment particles (known as xenophyae) in their fossils casts doubt on the possibility. Further, modern xenophyophores lack the regular hexagonal symmetry common to Paleodictyon. Modern examples of Paleodictyon have been discovered; however, examination failed to reveal stercomares, a hardened test, protoplasm, or xenophyophore DNA. The trace may alternately represent a burrow or a glass sponge. == The search for a living animal == The IMAX film Volcanoes of the Deep Sea describes the search for a living animal that produces the Paleodictyon, using the deep-water submersible DSV Alvin near volcanic vents that lie 3,500 metres (11,500 ft) underwater in the Mid-Atlantic Ridge. They found and took samples from many of the Paleodictyon nodosum honeycomb burrows. However, no creatures were found in any of them. They theorized that the burrows were being used for cultivating/trapping bacteria by whichever creature created them. == References == == External links == Volcanoes of the Deep Sea (2003) at IMDb
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{
"page_id": 13308663,
"source": null,
"title": "Paleodictyon"
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A field effect is the polarization of a molecule through space. The effect is a result of an electric field produced by charge localization in a molecule. This field, which is substituent and conformation dependent, can influence structure and reactivity by manipulating the location of electron density in bonds and/or the overall molecule. The polarization of a molecule through its bonds is a separate phenomenon known as induction. Field effects are relatively weak, and diminish rapidly with distance, but have still been found to alter molecular properties such as acidity. == Field sources == Field effects can arise from the electric dipole field of a bond containing an electronegative atom or electron-withdrawing substituent, as well as from an atom or substituent bearing a formal charge. The directionality of a dipole, and concentration of charge, can both define the shape of a molecule's electric field which will manipulate the localization of electron density toward or away from sites of interest, such as an acidic hydrogen. Field effects are typically associated with the alignment of a dipole field with respect to a reaction center. Since these are through space effects, the 3D structure of a molecule is an important consideration. A field may be interrupted by other bonds or atoms before propagating to a reactive site of interest. Atoms of differing electronegativities can move closer together resulting in bond polarization through space that mimics the inductive effect through bonds. Bicycloheptane and bicyclooctane (seen left) are pounds in which the change in acidity with substitution was attributed to the field effect. The C-X dipole is oriented away from the carboxylic acid group, and can draw electron density away because the molecule center is empty, with a low dielectric constant, so the electric field is able to propagate with minimal resistance. == Utility of
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"page_id": 56824574,
"source": null,
"title": "Field effect (chemistry)"
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|
effect == A dipole can align to stabilize or destabilize the formation or loss of a charge, thereby decreasing (if stabilized) or increasing (if destabilized) the activation barrier to a chemical event. Field effects can therefore tune the acidity or basicity of bonds within their fields by donating or withdrawing charge density. With respect to acidity, a common trend to note is that, inductively, an electron-withdrawing substituent in the vicinity of an acidic proton will lower the pKa (i.e. increase the acidity) and, correspondingly, an electron-donating substituent will raise the pKa. The reorganization of charge due to field effects will have the same result. An electric dipole field propagated through the space around, or in the middle of, a molecule in the direction of an acidic proton will decrease the acidity, while a dipole pointed away will increase the acidity and concomitantly elongate the X-H bond. These effects can therefore help to tune the acidity/basicity of a molecule to protonate/deprotonate a specific compound, or enhance hydrogen bond-donor ability for molecular recognition or anion sensing applications. Field effects have also been shown in substituted arenes to dominate the electrostatic potential maps, which are maps of electron density used to explain intermolecular interactions. == Evidence for field effects == Localized electronic effects are a combination of inductive and field effects. Due to the similarity in these effects, it is difficult to separate their contributions to the electronic structure of a molecule. There is, however, a large body of literature devoted to developing an understanding of the relative significance of induction and field effects by analyzing related compounds in an attempt to quantify each effect based on the present substituents and molecular geometry. For example, the three compounds to the right, all octanes, differ only in the number of linkers between the electron
|
{
"page_id": 56824574,
"source": null,
"title": "Field effect (chemistry)"
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withdrawing group X and an acidic functional group, which are approximately the same spatial distance apart in each compound. It is known that an electron-withdrawing substituent will decrease the pKa of a given proton (i.e. increase the acidity) inductively. If induction was the dominant effect in these compounds, acidity should increase linearly with the number of available inductive pathways (linkers). However, the experimental data shows that effect on acidity in related octanes and cubanes is very similar, and therefore the dominant effect must be through space. In the cis-11,12-dichloro-9,10-dihydro-9,10-ethano-2-anthroic acid syn and anti isomers seen below and to the left, the chlorines provide a field effect. The concentration of negative charge on each chlorine has a through space effect which can be seen in the relative pKa values. When the chlorines are pointed over the carboxylic acid group, the pKa is higher because loss of a proton is less favorable due to the increase in negative charge in the area. Loss of a proton results in a negative charge which is less stable if there is already an inherent concentration of electrons. This can be attributed to a field effect because in the same compound with the chlorines pointed away from the acidic group the pKa is lower, and if the effect were inductive the conformational position would not matter. == References ==
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{
"page_id": 56824574,
"source": null,
"title": "Field effect (chemistry)"
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Isaac Newton's rotating bucket argument (also known as Newton's bucket) is a thought experiment that was designed to demonstrate that true rotational motion cannot be defined as the relative rotation of the body with respect to the immediately surrounding bodies. It is one of five arguments from the "properties, causes, and effects" of "true motion and rest" that support his contention that, in general, true motion and rest cannot be defined as special instances of motion or rest relative to other bodies, but instead can be defined only by reference to absolute space. Alternatively, these experiments provide an operational definition of what is meant by "absolute rotation", and do not pretend to address the question of "rotation relative to what?" General relativity dispenses with absolute space and with physics whose cause is external to the system, with the concept of geodesics of spacetime. == Background == These arguments, and a discussion of the distinctions between absolute and relative time, space, place and motion, appear in a scholium at the end of Definitions sections in Book I of Newton's work, The Mathematical Principles of Natural Philosophy (1687) (not to be confused with General Scholium at the end of Book III), which established the foundations of classical mechanics and introduced his law of universal gravitation, which yielded the first quantitatively adequate dynamical explanation of planetary motion. Despite their embrace of the principle of rectilinear inertia and the recognition of the kinematical relativity of apparent motion (which underlies whether the Ptolemaic or the Copernican system is correct), natural philosophers of the seventeenth century continued to consider true motion and rest as physically separate descriptors of an individual body. The dominant view Newton opposed was devised by René Descartes, and was supported (in part) by Gottfried Leibniz. It held that empty space is a
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"page_id": 4864,
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metaphysical impossibility because space is nothing other than the extension of matter, or, in other words, that when one speaks of the space between things one is actually making reference to the relationship that exists between those things and not to some entity that stands between them. Concordant with the above understanding, any assertion about the motion of a body boils down to a description over time in which the body under consideration is at t1 found in the vicinity of one group of "landmark" bodies and at some t2 is found in the vicinity of some other "landmark" body or bodies. Descartes recognized that there would be a real difference, however, between a situation in which a body with movable parts and originally at rest with respect to a surrounding ring was itself accelerated to a certain angular velocity with respect to the ring, and another situation in which the surrounding ring were given a contrary acceleration with respect to the central object. With sole regard to the central object and the surrounding ring, the motions would be indistinguishable from each other assuming that both the central object and the surrounding ring were absolutely rigid objects. However, if neither the central object nor the surrounding ring were absolutely rigid then the parts of one or both of them would tend to fly out from the axis of rotation. For contingent reasons having to do with the Inquisition, Descartes spoke of motion as both absolute and relative. By the late 19th century, the contention that all motion is relative was re-introduced, notably by Ernst Mach (German 1883, English translation 1893). When, accordingly, we say that a body preserves unchanged its direction and velocity in space, our assertion is nothing more or less than an abbreviated reference to the entire universe.
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"page_id": 4864,
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"title": "Bucket argument"
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== The argument == Newton discusses a bucket (Latin: situla) filled with water hung by a cord. If the cord is twisted up tightly on itself and then the bucket is released, it begins to spin rapidly, not only with respect to the experimenter, but also in relation to the water it contains. (This situation would correspond to diagram B above.) Although the relative motion at this stage is the greatest, the surface of the water remains flat, indicating that the parts of the water have no tendency to recede from the axis of relative motion, despite proximity to the pail. Eventually, as the cord continues to unwind, the surface of the water assumes a concave shape as it acquires the motion of the bucket spinning relative to the experimenter. This concave shape shows that the water is rotating, despite the fact that the water is at rest relative to the pail. In other words, it is not the relative motion of the pail and water that causes concavity of the water, contrary to the idea that motions can only be relative, and that there is no absolute motion. (This situation would correspond to diagram D.) Possibly the concavity of the water shows rotation relative to something else: say absolute space? Newton says: "One can find out and measure the true and absolute circular motion of the water". In the 1846 Andrew Motte translation of Newton's words: If a vessel, hung by a long cord, is so often turned about that the cord is strongly twisted, then filled with water, and held at rest together with the water; after, by the sudden action of another force, it is whirled about in the contrary way, and while the cord is untwisting itself, the vessel continues for some time this motion; the
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surface of the water will at first be plain, as before the vessel began to move; but the vessel by gradually communicating its motion to the water, will make it begin sensibly to revolve, and recede by little and little, and ascend to the sides of the vessel, forming itself into a concave figure... This ascent of the water shows its endeavour to recede from the axis of its motion; and the true and absolute circular motion of the water, which is here directly contrary to the relative, discovers itself, and may be measured by this endeavour. ... And therefore, this endeavour does not depend upon any translation of the water in respect to ambient bodies, nor can true circular motion be defined by such translation. ...; but relative motions...are altogether destitute of any real effect. ... It is indeed a matter of great difficulty to discover, and effectually to distinguish, the true motions of particular bodies from the apparent; because the parts of that immovable space in which these motions are performed, do by no means come under the observations of our senses. The argument that the motion is absolute, not relative, is incomplete, as it limits the participants relevant to the experiment to only the pail and the water, a limitation that has not been established. In fact, the concavity of the water clearly involves gravitational attraction, and by implication the Earth also is a participant. Here is a critique due to Mach arguing that only relative motion is established: Newton's experiment with the rotating vessel of water simply informs us that the relative rotation of the water with respect to the sides of the vessel produces no noticeable centrifugal forces, but that such forces are produced by its relative rotations with respect to the mass of the
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earth and other celestial bodies. The degree in which Mach's hypothesis is integrated in general relativity is discussed in the article Mach's principle; it is generally held that general relativity is not entirely Machian. All observers agree that the surface of rotating water is curved. However, the explanation of this curvature involves centrifugal force for all observers with the exception of a truly stationary observer, who finds the curvature is consistent with the rate of rotation of the water as they observe it, with no need for an additional centrifugal force. Thus, a stationary frame can be identified, and it is not necessary to ask "Stationary with respect to what?": The original question, "relative to what frame of reference do the laws of motion hold?" is revealed to be wrongly posed. For the laws of motion essentially determine a class of reference frames, and (in principle) a procedure for constructing them. A supplementary thought experiment with the same objective of determining the occurrence of absolute rotation also was proposed by Newton: the example of observing two identical spheres in rotation about their center of gravity and tied together by a string. Occurrence of tension in the string is indicative of absolute rotation; see Rotating spheres. == Detailed analysis == The historic interest of the rotating bucket experiment is its usefulness in suggesting one can detect absolute rotation by observation of the shape of the surface of the water. However, one might question just how rotation brings about this change. Below are two approaches to understanding the concavity of the surface of rotating water in a bucket. === Newton's laws of motion === The shape of the surface of a rotating liquid in a bucket can be determined using Newton's laws for the various forces on an element of the surface.
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For example, see Knudsen and Hjorth. The analysis begins with the free body diagram in the co-rotating frame where the water appears stationary. The height of the water h = h(r) is a function of the radial distance r from the axis of rotation Ω, and the aim is to determine this function. An element of water volume on the surface is shown to be subject to three forces: the vertical force due to gravity Fg, the horizontal, radially outward centrifugal force FCfgl, and the force normal to the surface of the water Fn due to the rest of the water surrounding the selected element of surface. The force due to surrounding water is known to be normal to the surface of the water because a liquid in equilibrium cannot support shear stresses. To quote Anthony and Brackett: The surface of a fluid of uniform density..., if at rest, is everywhere perpendicular to the lines of force; for if this were not so, the force at a point on the surface could be resolved into two components, one perpendicular and the other tangent to the surface. But from the nature of a fluid, the tangential force would set up a motion of the fluid, which is contrary to the statement that the fluid is at rest. Moreover, because the element of water does not move, the sum of all three forces must be zero. To sum to zero, the force of the water must point oppositely to the sum of the centrifugal and gravity forces, which means the surface of the water must adjust so its normal points in this direction. (A very similar problem is the design of a banked turn, where the slope of the turn is set so a car will not slide off the road. The
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analogy in the case of rotating bucket is that the element of water surface will "slide" up or down the surface unless the normal to the surface aligns with the vector resultant formed by the vector addition Fg + FCfgl.) As r increases, the centrifugal force increases according to the relation (the equations are written per unit mass): F C f g l = m Ω 2 r , {\displaystyle F_{\mathrm {Cfgl} }=m\Omega ^{2}r\ ,} where Ω is the constant rate of rotation of the water. The gravitational force is unchanged at F g = m g , {\displaystyle F_{\mathrm {g} }=mg\ ,} where g is the acceleration due to gravity. These two forces add to make a resultant at an angle φ from the vertical given by tan φ = F C f g l F g = Ω 2 r g , {\displaystyle \tan \varphi ={\frac {F_{\mathrm {Cfgl} }}{F_{\mathrm {g} }}}={\frac {\Omega ^{2}r}{g}}\ ,} which clearly becomes larger as r increases. To ensure that this resultant is normal to the surface of the water, and therefore can be effectively nulled by the force of the water beneath, the normal to the surface must have the same angle, that is, tan φ = d h d r , {\displaystyle \tan \varphi ={\frac {\mathrm {d} h}{\mathrm {d} r}}\ ,} leading to the ordinary differential equation for the shape of the surface: d h d r = Ω 2 r g , {\displaystyle {\frac {\mathrm {d} h}{\mathrm {d} r}}={\frac {\Omega ^{2}r}{g}}\ ,} or, integrating: h ( r ) = h ( 0 ) + 1 2 g ( Ω r ) 2 , {\displaystyle h(r)=h(0)+{\frac {1}{2g}}\left(\Omega r\right)^{2}\ ,} where h(0) is the height of the water at r = 0. In other words, the surface of the water is
|
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"page_id": 4864,
"source": null,
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parabolic in its dependence upon the radius. === Potential energy === The shape of the water's surface can be found in a different, very intuitive way using the interesting idea of the potential energy associated with the centrifugal force in the co-rotating frame. In a reference frame uniformly rotating at angular rate Ω, the fictitious centrifugal force is conservative and has a potential energy of the form: U C f g l = − 1 2 m Ω 2 r 2 , {\displaystyle {U}_{\mathrm {Cfgl} }=-{\frac {1}{2}}m\Omega ^{2}r^{2}\ ,} where r is the radius from the axis of rotation. This result can be verified by taking the gradient of the potential to obtain the radially outward force: F C f g l = − ∂ ∂ r U C f g l {\displaystyle F_{\mathrm {Cfgl} }=-{\frac {\partial }{\partial r}}{U}_{\mathrm {Cfgl} }} = m Ω 2 r . {\displaystyle =m\Omega ^{2}r\ .} The meaning of the potential energy (stored work) is that movement of a test body from a larger radius to a smaller radius involves doing work against the centrifugal force and thus gaining potential energy. But this test body at the smaller radius where its elevation is lower has now lost equivalent gravitational potential energy. Potential energy therefore explains the concavity of the water surface in a rotating bucket. Notice that at equilibrium the surface adopts a shape such that an element of volume at any location on its surface has the same potential energy as at any other. That being so, no element of water on the surface has any incentive to move position, because all positions are equivalent in energy. That is, equilibrium is attained. On the other hand, were surface regions with lower energy available, the water occupying surface locations of higher potential energy would move
|
{
"page_id": 4864,
"source": null,
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to occupy these positions of lower energy, inasmuch as there is no barrier to lateral movement in an ideal liquid. We might imagine deliberately upsetting this equilibrium situation by somehow momentarily altering the surface shape of the water to make it different from an equal-energy surface. This change in shape would not be stable, and the water would not stay in our artificially contrived shape, but engage in a transient exploration of many shapes until non-ideal frictional forces introduced by sloshing, either against the sides of the bucket or by the non-ideal nature of the liquid, killed the oscillations and the water settled down to the equilibrium shape. To see the principle of an equal-energy surface at work, imagine gradually increasing the rate of rotation of the bucket from zero. The water surface is flat at first, and clearly a surface of equal potential energy because all points on the surface are at the same height in the gravitational field acting upon the water. At some small angular rate of rotation, however, an element of surface water can achieve lower potential energy by moving outward under the influence of the centrifugal force; think of an object moving with the force of gravity closer to the Earth's center: the object lowers its potential energy by complying with a force. Because water is incompressible and must remain within the confines of the bucket, this outward movement increases the depth of water at the larger radius, increasing the height of the surface at larger radius, and lowering it at smaller radius. The surface of the water becomes slightly concave, with the consequence that the potential energy of the water at the greater radius is increased by the work done against gravity to achieve the greater height. As the height of water increases, movement
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"page_id": 4864,
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toward the periphery becomes no longer advantageous, because the reduction in potential energy from working with the centrifugal force is balanced against the increase in energy working against gravity. Thus, at a given angular rate of rotation, a concave surface represents the stable situation, and the more rapid the rotation, the more concave this surface. If rotation is arrested, the energy stored in fashioning the concave surface must be dissipated, for example through friction, before an equilibrium flat surface is restored. To implement a surface of constant potential energy quantitatively, let the height of the water be h ( r ) {\displaystyle h(r)\,} : then the potential energy per unit mass contributed by gravity is g h ( r ) {\displaystyle gh(r)\ } and the total potential energy per unit mass on the surface is U = U 0 + g h ( r ) − 1 2 Ω 2 r 2 {\displaystyle {U}={U}_{0}+gh(r)-{\frac {1}{2}}\Omega ^{2}r^{2}\,} with U 0 {\displaystyle {U}_{0}} the background energy level independent of r. In a static situation (no motion of the fluid in the rotating frame), this energy is constant independent of position r. Requiring the energy to be constant, we obtain the parabolic form: h ( r ) = Ω 2 2 g r 2 + h ( 0 ) , {\displaystyle h(r)={\frac {\Omega ^{2}}{2g}}r^{2}+h(0)\ ,} where h(0) is the height at r = 0 (the axis). See Figures 1 and 2. The principle of operation of the centrifuge also can be simply understood in terms of this expression for the potential energy, which shows that it is favorable energetically when the volume far from the axis of rotation is occupied by the heavier substance. == See also == == References == == Further reading == Brian Greene (2004). "Chapter 2, The Universe and
|
{
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the Bucket". The Fabric of the Cosmos: Space, Time, and the Texture of Reality. A A Knopf. ISBN 0-375-41288-3. The isotropy of the cosmic microwave background radiation is another indicator that the universe does not rotate. See: R. B. Partridge (1995). 3 K: The Cosmic Microwave Background Radiation. Cambridge University Press. pp. 279–280. ISBN 0-521-35254-1. D. Lynden-Bell (1996). Relativistic Astrophysics (Igor' Dmitrievich Novikov, Bernard Jean Trefor Jones, Draza Marković (Editors) ed.). Cambridge University Press. p. 167. ISBN 0-521-62113-5. Ralph A. Alpher and Robert Herman (1975). Big bang cosmology and the cosmic black-body radiation (in Proc. Am. Philos. Soc. vol. 119, no. 5 (1975) ed.). American Philosophical Society. pp. 325–348. ISBN 9781422371077. == External links == Newton's Views on Space, Time, and Motion from Stanford Encyclopedia of Philosophy, article by Robert Rynasiewicz. At the end of this article, loss of fine distinctions in the translations as compared to the original Latin text is discussed. Life and Philosophy of Leibniz see section on Space, Time and Indiscernibles for Leibniz arguing against the idea of space acting as a causal agent. Newton's Bucket An interactive applet illustrating the water shape, and an attached PDF file with a mathematical derivation of a more complete water-shape model than is given in this article.
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The Frank–Caro process, also called cyanamide process, is the nitrogen fixation reaction of calcium carbide with nitrogen gas in a reactor vessel at about 1,000 °C. The reaction is exothermic and self-sustaining once the reaction temperature is reached. Originally the reaction took place in large steel cylinders with an electrical resistance element providing initial heat to start the reaction. Modern production uses rotating ovens. The synthesis produces a solid mixture of calcium cyanamide (CaCN2), also known as nitrolime, and carbon. CaC2 + N2 → CaCN2 + C == History == The Frank–Caro process was the first commercial process that was used worldwide to fix atmospheric nitrogen. The product was used as fertilizer and commercially known as Lime-Nitrogen. Nitrolim or Kalkstickstoff in German. The method was developed by the German chemists Adolph Frank and Nikodem Caro between 1895 and 1899. In its first decades, the world market for inorganic fertilizer was dominated by factories utilizing the cyanamide process. === Production facilities === The first full-scale factories were established in 1905 in Piano d´Orta (Italy) and Westeregeln (Germany). From 1908 the Frank–Caro process was used at North Western Cyanamide Company at Odda, Norway. With an annual production capacity of 12,000 ton from 1909, the factory at Odda was by far the largest in the world. At this time, first phase factories were established in Briançon (France), Martigny (Switzerland), Bromberg (Prussia/Poland) and Knapsack (Germany). The cyanamide factory at Odda ceased operation in 2002. It is still intact and is a Norwegian candidate to the UNESCO World Heritage List. === Haber process === In the 1920s the more energy-efficient Haber process gradually took over in the nitrogen fertilizer production, but Frank-Caro process has continued to produce a useful chemical feedstock. In 1945 the production of calcium cyanamide reached a peak of an estimated 1.5
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"page_id": 7541505,
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"title": "Frank–Caro process"
}
|
million tons a year. === Patent === German patent nr. DE 88363 (1895) == See also == Odda process Birkeland–Eyde process Haber–Bosch process Linde–Frank–Caro process, a method to produce hydrogen from water gas == References == == External links == Guide to the Papers of Adolf Frank (1834–1916) Archived 2011-07-25 at the Wayback Machine
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{
"page_id": 7541505,
"source": null,
"title": "Frank–Caro process"
}
|
From 1948 to 1975, the U.S. Army Chemical Corps conducted classified human subject research at the Edgewood Arsenal facility in Maryland. These experiments began after the conclusion of World War II, and continued until the public became aware of the experiments, resulting in significant outcry. The purpose was to evaluate the impact of low-dose chemical warfare agents on military personnel and to test protective clothing, pharmaceuticals, and vaccines. A small portion of these studies were directed at psychochemical warfare; grouped under the title "Medical Research Volunteer Program" (1956–1975), driven by intelligence requirements and the need for new and more effective interrogation techniques. Overall, about 6,720 soldiers took part in these experiments that involved exposures to more than 250 different chemicals, according to the Department of Defense (DoD). Some of the volunteers exhibited symptoms at the time of exposure to these agents but long-term follow-up was not planned as part of the DoD studies. The experiments were abruptly terminated by the Army in late 1975 amidst an atmosphere of scandal and recrimination as lawmakers accused researchers of questionable ethics. Many official government reports and civilian lawsuits followed in the wake of the controversy. The chemical agents tested on volunteers included chemical warfare agents and other related agents: Anticholinesterase nerve agents (VX, sarin) and common organophosphorus (OP) and carbamate pesticides Mustard agents Nerve agent antidotes including atropine and scopolamine Nerve agent reactivators, e.g. the common OP antidote 2-PAM chloride Psychoactive agents including LSD, PCP, cannabinoids, and BZ Irritants and riot control agents Alcohol and caffeine == History == === Background and rationale === After the conclusion of World War II, U.S. military researchers obtained formulas for the three nerve gases developed by the Nazis—tabun, soman, and sarin. In 1947, the first steps of planning began when Dr. Alsoph H. Corwin, a professor
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of chemistry at Johns Hopkins University wrote the Chemical Corps Technical Command positing the potential for the use of specialized enzymes as so called "toxicological warfare agents". He went on to suggest that with intensive research, substances that depleted certain necessary nutrients could be found, which would, when administered on the battlefield, incapacitate enemy combatants. In 1948, the US Army Edgewood Chemical Biological Center began conducting research using the aforementioned nerve gases. These studies included a classified human subjects component at least as early as 1948, when "psychological reactions" were documented in Edgewood technicians. Initially, such studies focused solely on the lethality of the gases and its treatment and prevention. A classified report entitled "Psychochemical Warfare: A New Concept of War" was produced in 1949 by Luther Wilson Greene, Technical Director of the Chemical and Radiological Laboratories at Edgewood. Greene called for a search for novel psychoactive compounds that would create the same debilitating mental side effects as those produced by nerve gases, but without their lethal effect. In his words,Throughout recorded history, wars have been characterized by death, human misery, and the destruction of property; each major conflict being more catastrophic than the one preceding it ... I am convinced that it is possible, by means of the techniques of psychochemical warfare, to conquer an enemy without the wholesale killing of his people or the mass destruction of his property. In the late 1940s and early 1950s, the U.S. Army worked with Harvard anesthesiologist Henry K. Beecher at its interrogation center at Camp King in Germany on the use of psychoactive compounds (mescaline, LSD), including human subject experiments and the debriefing of former Nazi physicians and scientists who had worked along similar lines before the end of the war. In the 1950s, some officials in the U.S. Department of
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Defense publicly asserted that many "forms of chemical and allied warfare as more 'humane' than existing weapons. For example, certain types of 'psychochemicals' would make it possible to paralyze temporarily entire population centers without damage to homes and other structures." Soviet advances in the same field were cited as a special incentive giving impetus to research efforts in this area, according to testimony by Maj. Gen. Marshall Stubbs, the Army's chief chemical officer. In June 1955, the United States Department of Defense appointed a so-called Ad Hoc Study Group on Psychochemical Agents, which seems to have acted as a central authority on the research of psychochemical at Edgewood Arsenal and other installations where such experimentation occurred. General William M. Creasy, former chief chemical officer, U.S. Army, testified to the U.S. House of Representatives in 1959 that "provided sufficient emphasis is put behind it, I think the future lies in the psychochemicals." This was alarming enough to a Harvard psychiatrist, E. James Lieberman, that he published an article entitled "Psychochemicals as Weapons" in The Bulletin of the Atomic Scientists in 1962. Lieberman, while acknowledging that "most of the military data" on the research ongoing at the Army Chemical Center was "secret and unpublished", asserted that "There are moral imponderables, such as whether insanity, temporary or permanent, is a more 'humane' military threat than the usual afflictions of war." == The experiments == The Edgewood Arsenal human experiments took place from approximately 1948 to 1975 at the Medical Research Laboratories—which is now known as the U.S. Army Medical Research Institute of Chemical Defense (USAMRICD)—at the Edgewood Area, Aberdeen Proving Ground, Maryland. The experiments involved at least 254 chemical substances, but focused mainly on midspectrum incapacitants, such as LSD, THC derivatives, benzodiazepines, and BZ. Around 7,000 US military personnel and 1,000 civilians were
|
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test subjects over almost three decades. A result of these experiments was that BZ was weaponized, although never deployed. According to a DOD FAQ, the Edgewood Arsenal experiments involved the following "rough breakout of volunteer hours against various experimental categories": === Acetylcholine related experiments === Much of the experimentation at Edgewood Arsenal surrounded the modulation of acetylcholine or acetylcholinesterase, or the deactivation and reactivation of substances which did the same. These experiments represented a significant enough proportion of the total experimentation to earn a dedicated volume in the main experimental documentation. Much of the follow up data on the acetylcholine related experiments are lacking or entirely missing, due to a combination of remaining classification and failures on the part of the United States Department of Veterans Affairs and United States Department of Defense to follow the subjects of the experimentation. ==== Anticholinesterase experiments ==== Anticholinesterases are substances that interfere with the central nervous system and the peripheral nervous system by inhibiting acetylcholinesterase and therefore sustaining the effect of acetylcholine or butyrylcholine within the chemical synapses, resulting in a cholinergic crisis, and possibly death if untreated. Long term side effects of exposure to anticholinesterases, including at levels below the threshold for profound illness and death can include paralysis and peripheral neuropathy, sleep disturbance, genetic mutation and cancer. In total, 1,406 subjects were tested with 16 agents, some of which included reactivating agents and protective agents. ==== Anticholinergic experiments ==== Anticholinergics are substances that interfere with the central nervous system and the peripheral nervous system by inhibiting acetylcholine, resulting in what is essentially the opposite effect of an cholinesterase inhibitor to the extreme. This can result in anticholinergic syndrome, and possibly death if untreated. Available data from both experiment patients and pharmaceutical research indicates that short-term exposure to anticholinergic compounds, especially the
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"page_id": 5640964,
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extremely limited exposures described in the documentation is associated with no long-term effects. It is important to note however, that in the decades since their introduction to medical use, research has begun to suggest a causal relationship between long term anticholinergic drug use and later development or worsening of dementia. In total, 1,752 subjects were tested with 21 agents, some of whom received exposure to more than one chemical agent. ==== Cholinesterase reactivator experiments ==== Cholinesterase reactivators are substances which reactivate acetylcholinesterase which has been inactivated by an anticholinesterase. This action can be precipitated through a variety of mechanisms, including directly binding and deactivating the anticholinesterase itself, blocking the reaction between the anticholinesterase and the acetylcholinesterase, changing the release of acetylcholine, blocking acetylcholine's cholinolytic effect, or by increasing the excretion of the anticholinesterase. Available data from the experiments and from prescribing information from modern marketing of these substances concludes that little risk exists of long term effects from exposure. It is noted, however, in both the prescribing information for modern variants and in toxicological research on the subject that it has been the subject of insufficient research to conclude this beyond a reasonable doubt. In total, 219 subjects were tested with 4 agents. === Psychochemical related experiments === The 1976 report on the matter identifies the sole objective of the psychochemical experiments as determining the impact on morale and efficacy such agents would have on military units. It appears that these experiments specifically were first called for in 1954 after the attendees of the First Psychochemical Conference informed the Department of Defense that human trials were indicated. In 1957, the first report of such trials were received, detailing a four-person experiment wherein they attempted to successfully decontaminate themselves of a mock agent while under the influence of LSD. ==== LSD
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experiments ==== The LSD experiments are perhaps the best documented of the psychochemical experiments of the time, garnering at least two significant independent reports. LSD is a Psychedelic drug that acts as a dopamine and serotonin agonist precipitating a hallucinogenic effect, leading to hallucinations, euphoria, and a wide variety of physiological symptoms. Available data describes a wide range of doses used in the experiments, from approximately 2μg/kg to 16μg/kg A typical dose for recreational use is around 100μg, or about 1.1μg/kg for the average adult male in the U.S., meaning the lowest dose used in experimentation was almost twice the typical recreational dose, and the highest dose exceeded fifteen times the typical recreational dose. Because of limited documentation, it is difficult to ascertain which experiments occurred at which installations, but available documentation describes several general types of experiments; which included presenting individuals with radar symbols for interpretation, having them track a simulated aircraft, having them read a map, having them interpret meteorological data, and having them attempt to defend an installation against a simulated hostile air craft attack with 40-mm antiaircraft automatic weapons. Results varied between experiments, but typically showed significant impairment at all doses, with impairment increasing as dose did. Available data from the experiments concluded that long term effects from LSD exposure in not only the Edgewood Arsenal Experiments, but in the other associated experiments conducted concurrently by the Army Chemical Corps as well were minimal, with the exception of a possible small increase in congenital heart disease in offspring of the experimental subjects, and neuropsychological abnormalities in 9% of the participants which could not be explained by etiological explanations other than LSD exposure, most of which were considered mild. It is reported that all testing of LSD at Edgewood Arsenal and in general on behalf of the
|
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"page_id": 5640964,
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Army Chemical Corps was abandoned on or around April 1963. ==== BZ experiments ==== 3-Quinuclidinyl benzilate, or BZ is a substance that interferes with the central nervous system and the peripheral nervous system by inhibiting acetylcholine. Existing documentation admits only that the substance was tested at Edgewood Arsenal, and all other data, including the medical records from the subjects are completely missing. Because of the extremely limited data, speculation on possible side effects from exposure is impossible. === Scandal and termination === In September 1975, the Medical Research Volunteer Program was discontinued and all resident volunteers were removed from the Edgewood installation. The founder and director of the program, Van Murray Sim, was called before Congress and chastised by outraged lawmakers, who questioned the absence of follow-up care for the human volunteers. An Army investigation subsequently found no evidence of serious injuries or deaths associated with the MRVP, but deplored both the recruiting process and the informed consent approach, which they characterized as "suggest[ing] possible coercion". == Aftermath == === Government reports === 1982-85 IOM report The Institute of Medicine (IOM) published a three-volume report on the Edgewood research in 1982–1985, Possible Long-Term Health Effects of Short-Term Exposure to Chemical Agents. The three volumes were: Vol. 1, "Anticholinesterases and Anticholinergics" (1982). Vol. 2, "Cholinesterase Reactivators, Psychochemicals and Irritants and Vesicants" (1984) Vol. 3, "Final Report: Current Health Status of Test Subjects" (1985) The National Academy of Sciences, which oversees the IOM, sent a questionnaire to all of the former volunteers that could be located, approximately 60% of the total. The lack of a detailed record hampered the investigation. The study could not rule out long-term health effects related to exposure to the nerve agents. It concluded that "Whether the subjects at Edgewood incurred these changes [depression, cognitive deficits, tendency to
|
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"page_id": 5640964,
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suicide] and to what extent they might now show these effects are not known". With regard specifically to BZ and related compounds, the IOM study concluded that "available data suggest that long-term toxic effects and/or delayed sequellae are unlikely". 2004 GAO report A Government Accounting Office report of May 2004, Chemical and Biological Defense: DOD Needs to Continue to Collect and Provide Information on Tests and Potentially Exposed Personnel (pp. 1, 24), stated: [In 1993 and 1994] we [...] reported that the Army Chemical Corps conducted a classified medical research program for developing incapacitating agents. This program involved testing nerve agents, nerve agent antidotes, psycho chemicals, and irritants. The chemicals were given to volunteer service members at Edgewood Arsenal, Maryland; Dugway Proving Ground, Utah; and Forts Benning, Bragg, and McClellan. In total, Army documents identified 7,120 Army and Air Force personnel who participated in these tests. Further, GAO concluded that precise information on the scope and the magnitude of tests involving human subjects was not available, and the exact number of human subjects might never be known. === Safety debates === The official position of the Department of Defense, based on the three-volume set of studies by the Institute of Medicine mentioned above, is that they "did not detect any significant long-term health effects on the Edgewood Arsenal volunteers". The safety record of the Edgewood Arsenal experiments was also defended in the memoirs of psychiatrist and retired colonel James Ketchum, a key scientist: Over a period of 20 years, more than 7,000 volunteers spent an estimated total of 14,000 months at Edgewood Arsenal. To my knowledge, not one of them died or suffered a serious illness or permanent injury. That adds up to 1,167 man-years of survival. Statistically, at least one out of a thousand young soldiers chosen at random
|
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might be expected to expire during any one-year period. By this logic, Edgewood was possibly the safest military place in the world to spend two months. As late as 2014, information was incomplete; IOM could not conduct adequate medical studies related to similar former US biowarfare programs, because relevant classified documents had not been declassified and released. The committee's understanding is that additional, and potentially relevant, material on SHAD tests exists and remains classified. The IOM committee requested declassification of 21 additional elements from at least nine documents from DoD in August 2012. In January 2014, an additional request was made for release of multiple films made of Project SHAD tests. None of the requested materials were cleared for public release as of this writing (2016). Even a book critical of the program, written by Lynn C. Klotz and Edward J. Sylvester, acknowledges that: Unlike the CIA program, research subjects [at Edgewood] all signed informed consent forms, both a general one and another related to any experiment they were to participate in. Experiments were carried out with safety of subjects a principal focus. [...] At Edgewood, even at the highest doses it often took an hour or more for incapacitating effects to show, and the end-effects usually did not include full incapacitation, let alone unconsciousness. After all, the Edgewood experimenters were focused on disabling soldiers in combat, where there would be tactical value simply in disabling the enemy. === Lawsuits === The U.S. Army believed that legal liability could be avoided by concealing the experiments. However once the experiments were uncovered, the US Senate also concluded questionable legality of the experiments and strongly condemned them.In the Army's tests, as with those of the CIA, individual rights were ... subordinated to national security considerations; informed consent and follow-up examinations of subjects
|
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were neglected in efforts to maintain the secrecy of the tests. Finally, the command and control problems which were apparent in the CIA's programs are paralleled by a lack of clear authorization and supervision in the Army's programs.(S. Rep., at 411.[5]) In the 1990s, the law firm Morrison & Foerster agreed to take on a class-action lawsuit against the government related to the Edgewood volunteers. The plaintiffs collectively referred to themselves as the "Test Vets". In 2009 a lawsuit was filed by veterans rights organizations Vietnam Veterans of America, and Swords to Plowshares, and eight Edgewood veterans or their families against CIA, the U.S. Army, and other agencies. The complaint asked the court to determine that defendants' actions were illegal and that the defendants have a duty to notify all victims and to provide them with health care. In the suit, Vietnam Veterans of America, et al. v. Central Intelligence Agency, et al. Case No. CV-09-0037-CW, U.S.D.C. (N.D. Cal. 2009), the plaintiffs did not seek monetary damages. Instead, they sought only declaratory and injunctive relief and redress for what they claimed was several decades of neglect and the U.S. government's use of them as human guinea pigs in chemical and biological agent testing experiments. The plaintiffs cited: The use of troops to test nerve gas, psychochemicals, and thousands of other toxic chemical or biological substances. A failure to secure informed consent and other widespread failures to follow the precepts of U.S. and international law regarding the use of human subjects, including the 1953 Wilson Directive and the Nuremberg Code. A refusal to satisfy their legal and moral obligations to locate the victims of experiments or to provide health care or compensation to them A deliberate destruction of evidence and files documenting their illegal actions, actions which were punctuated by fraud,
|
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deception, and a callous disregard for the value of human life. On July 24, 2013, United States District Court Judge Claudia Wilken issued an order granting in part and denying in part plaintiffs' motion for summary judgment and granting in part and denying in part defendants' motion for summary judgment. The court resolved all of the remaining claims in the case and vacated trial. The court granted the plaintiffs partial summary judgment concerning the notice claim: summarily adjudicating in plaintiffs' favor, finding that "the Army has an ongoing duty to warn" and ordering "the Army, through the DVA or otherwise, to provide test subjects with newly acquired information that may affect their well-being that it has learned since its original notification, now and in the future as it becomes available". The court granted the defendants' motion for summary judgment with respect to the other claims. On appeal in Vietnam Veterans of America v. Central Intelligence Agency, a panel majority held in July 2015 that Army Regulation 70-25 (AR 70-25) created an independent duty to provide ongoing medical care to veterans who participated in U.S. chemical and biological testing programs. The prior finding held that the Army has an ongoing duty to seek out and provide "notice" to former test participants of any new information that could potentially affect their health. == List of notable EA (Edgewood Arsenal) numbered chemicals == == List of notable CS (Chemical Structure) and CAS (Chemical Abstracts Service) numbered chemicals used in the Edgewood Arsenal Experiments == The following chemicals were identified by the National Academies of Sciences, Engineering, and Medicine as having been used in the Edgewood Arsenal Experiments, though they did not receive an EA number designation. == See also == THC-O-acetate CB military symbol United States chemical weapons program Edgewood Chemical Biological Center
|
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Human experimentation in the United States Swords to Plowshares United States v. Stanley == References == === General sources === Two autobiographical books from psychiatrists conducting human experiments at Edgewood have been self-published: Men and Poisons: The Edgewood Volunteers and the Army Chemical Warfare Research Program (2005), Xlibris Corporation, 140pp, was written by Malcolm Baker Bowers Jr, who went on to become a prof of psychiatry at Yale. Bowers' book is a "fictionalized" account with names changed. Chemical Warfare Secrets Almost Forgotten, A Personal Story of Medical Testing of Army Volunteers with Incapacitating Chemical Agents During the Cold War (1955–1975) (2006, 2nd edition 2007), foreword by Alexander Shulgin, ChemBook, Inc., 360 pp, was written by Ketchum who was a key player after 1960 and went on to become a professor at the University of California, Los Angeles. The Vanderbilt University Television News Archive has two videos about the experiments, both from a July 1975 NBC Evening News segment. NBC newsman John Chancellor reported on how Norman Augustine, then-acting Secretary of Army, ordered a probe of Army use of LSD in soldier and civilian experiments. Correspondent Tom Pettit reported on Major General Lloyd Fellenz, from Edgewood Arsenal, who explained how the experiments there were about searching for humane weapons, adding that the use of LSD was unacceptable. Journalist Linda Hunt, citing records from the U.S. National Archives, revealed that eight German scientists worked at Edgewood, under Project Paperclip. Hunt used this finding to assert that in this collaboration, US and former Nazi scientists "used Nazi science as a basis for Dachau-like experiments on over 7,000 U.S. soldiers". A The Washington Post article, dated July 23, 1975, by Bill Richards ("6,940 Took Drugs") reported that a top civilian drug researcher for the Army said a total of 6,940 servicemen had been involved
|
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in Army chemical and drug experiments, and that, furthermore, the tests were proceeding at Edgewood Arsenal as of the date of the article. Two TV documentaries, with different content but confusingly similar titles were broadcast: Bad Trip to Edgewood (1993) on ITV Yorkshire Bad Trip to Edgewood (1994) on A&E Investigative Reports. In 2012, the Edgewood/Aberdeen experiments were featured on CNN and in The New Yorker magazine. === Citations === == External links == Edgewood Test Vets: Vietnam Veterans of America, et al. v. Central Intelligence Agency, et al. Case No. CV-09-0037-CW, U.S.D.C. (N.D. Cal. 2009), Morrison & Foerster LLP, August 7, 2013 Hunt, Secret Agenda: The U.S. Government, Nazi Scientists and Project Paperclip 1945-1991. Secrets of Edgewood, The New Yorker, December 26, 2012 Edgewood/Aberdeen Experiments, U.S. Department of Veterans Affairs David S. Martin, Vets feel abandoned after secret drug experiments, CNN, March 1, 2012 Tom Bowman, Former sergeant seeks compensation for LSD testing at Edgewood Arsenal, July 11, 1991, The Baltimore Sun
|
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"page_id": 5640964,
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Cold vapour atomic fluorescence spectroscopy (CVAFS) is a subset of the analytical technique known as atomic fluorescence spectroscopy (AFS). == Use for mercury detection == Used in the measurement of trace amounts of volatile heavy metals such as mercury, cold vapour AFS makes use of the unique characteristic of mercury that allows vapour measurement at room temperature. Free mercury atoms in a carrier gas are excited by a collimated ultraviolet light source at a wavelength of 253.7 nanometres. The excited atoms re-radiate their absorbed energy (fluoresce) at this same wavelength. Unlike the directional excitation source, the fluorescence is omnidirectional and may thus be detected using a photomultiplier tube or UV photodiode. Gold coated traps may be used to collect mercury in ambient air or other media. The traps are then heated, releasing the mercury from the gold while passing argon through the cartridge. This preconcentrates the mercury, increasing sensitivity, and also transfers the mercury into an inert gas. == Transportable analysers == A number of companies have commercialized mercury detection via CVAFS and produced transportable analysers capable of measuring mercury in ambient air. These devices can measure levels in the low parts per quadrillion range (10−15). == EPA-approved methods == Various analytical methods approved by the United States Environmental Protection Agency (EPA) for measuring mercury in wastewater are in common use. EPA Methods 245.7 and 1631 are commonly used for measurement of industrial wastewater using CVAFS. == See also == Other analytical techniques suitable for analyzing heavy metals in air or water: Inductively coupled plasma mass spectrometry Atomic absorption spectroscopy == References ==
|
{
"page_id": 5182215,
"source": null,
"title": "Cold vapour atomic fluorescence spectroscopy"
}
|
Pokkesviricetes is a class of viruses. == Nomenclature == The class, Pokkesviricetes, is derived from pockes, the Middle English word for pox as in referring to the disease associated to certain members of Poxviridae. == Orders == The following orders are recognized: Asfuvirales Chitovirales == References ==
|
{
"page_id": 63771405,
"source": null,
"title": "Pokkesviricetes"
}
|
Mordehai "Moti" Milgrom (Hebrew: מרדכי "מוטי" מילגרום) is an Israeli physicist and professor in the department of Particle Physics and Astrophysics at the Weizmann Institute in Rehovot, Israel. == Biography == He received his B.Sc. degree from the Hebrew University of Jerusalem in 1966. Later he studied at the Weizmann Institute of Science and completed his doctorate in 1972. Before 1980 he worked primarily on high-energy astrophysics and became well known for his kinematical model of the star system SS 433. In the academic years 1980–1981 and 1985–1986 he was at the Institute for Advanced Study in Princeton. In 1983, he proposed modified Newtonian dynamics (MOND) as an alternative to the dark matter and galaxy rotation curve problems, although preliminary work and discussions on this subject started as early as 1981. == Milgrom and modified Newtonian dynamics == Milgrom is a prominent proponent of the hypothesis that Newton's law of universal gravitation should be modified for very small accelerations, typically of the order of 10−11g and less. == Personal life == Milgrom is married and has three daughters. == See also == Cosmic rays Gamma-ray burst Gamma ray and x-ray sources. == References == == Further reading == Milgrom, Mordehai (Aug 2002), "Does Dark Matter Really Exist?" (PDF), Scientific American, pp. 42–50, 52, archived from the original (PDF) on 2004-09-19 Schilling, Govert (April 2007), "Battlefield Galactica: Dark Matter vs. MOND" (PDF), Sky & Telescope, vol. 113, no. 4, pp. 30–36, Bibcode:2007S&T...113d..30S Zhiping Li, Ran Li. (30 April 2014). "The relativistic astrodynamics of spiral tracks, localized equivalence principle and the dark matter problem of our Milky Way galaxy". Sciencepaper Online. == External links == MOND - A Pedagogical Review - M. Milgrom, 2001 M. Milgrom @ Astrophysics Data System "MOND: Scale invariance at low accelerations - an alternative to the dark
|
{
"page_id": 660242,
"source": null,
"title": "Mordehai Milgrom"
}
|
Universe". YouTube. Weizmann Institute of Science. May 11, 2020. Archived from the original on 2021-12-21.
|
{
"page_id": 660242,
"source": null,
"title": "Mordehai Milgrom"
}
|
Contagium vivum fluidum (Latin: "contagious living fluid") was a phrase first used to describe a virus, and underlined its ability to slip through the finest ceramic filters then available, giving it almost liquid properties. Martinus Beijerinck (1851–1931), a Dutch microbiologist and botanist, first used the term when studying the tobacco mosaic virus, becoming convinced that the virus had a liquid nature. The word "virus", from the Latin for "poison", was originally used to refer to any infectious agent, and gradually became used to refer to infectious particles. Bacteria could be seen under microscope, and cultured on agar plates. In 1890, Louis Pasteur declared "tout virus est un microbe": "all infectious diseases are caused by microbes". In 1892, Dmitri Ivanovsky discovered that the cause of tobacco mosaic disease could pass through Chamberland's porcelain filter. Infected sap, passed through the filter, retained its infectious properties. Ivanovsky thought the disease was caused by an extremely small bacteria, too small to see under microscope, which secreted a toxin. It was this toxin, he thought, which passed through the filter. However, he was unable to culture the purported bacteria. In 1898, Beijerinck independently found the cause of the disease could pass through porcelain filters. He disproved Ivanovsky's toxin theory by demonstrating infection in series. He found that although he could not culture the infectious agent, it would diffuse through an agar gel. This diffusion inspired him to put forward the idea of a non-cellular "contagious living fluid", which he called a "virus". This was somewhere between a molecule and a cell. Ivanovsky, irked that Beijerinck had not cited him, demonstrated that particles of ink could also diffuse through agar gel, thus leaving the particulate or fluid nature of the pathogen unresolved. Beijerinck's critics including Ivanovsky argued that the idea of a "contagious living fluid" was
|
{
"page_id": 38146835,
"source": null,
"title": "Contagium vivum fluidum"
}
|
a contradiction in terms. However, Beijerinck only used the phrase "contagium vivum fluidum" in the title of his paper, using the word "virus" throughout. Other scientists began to identify other diseases caused by infectious agents which could pass through a porcelain filter. These became known as "filterable viruses", and later just "viruses". In 1923 Edmund Beecher Wilson wrote "We have now arrived at a borderland, where the cytologist and the colloidal chemist are almost within hailing distance of each other".: 34 In 1935 American biochemist and virologist Wendell Meredith Stanley was able to crystallize and isolate the tobacco mosaic virus.: 47 Stanley found the crystals were effectively living chemicals: they could be dissolved and would regain their infectious properties.: 46 The tobacco mosaic virus was the first virus to be photographed with an electron microscope, in 1939. Over the second half of the twentieth century, more than 2,000 virus species infecting animals, plants and bacteria were discovered. == References == == External links == A Contagium vivum fluidum as the Cause of the Mosaic Diseases of Tobacco Leaves – Martinus W. Beijerinck (1899)
|
{
"page_id": 38146835,
"source": null,
"title": "Contagium vivum fluidum"
}
|
In orbital mechanics, a Lissajous orbit (pronounced [li.sa.ʒu]), named after Jules Antoine Lissajous, is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system with minimal propulsion. Lyapunov orbits around a Lagrangian point are curved paths that lie entirely in the plane of the two primary bodies. In contrast, Lissajous orbits include components in this plane and perpendicular to it, and follow a Lissajous curve. Halo orbits also include components perpendicular to the plane, but they are periodic, while Lissajous orbits are usually not. In practice, any orbits around Lagrangian points L1, L2, or L3 are dynamically unstable, meaning small departures from equilibrium grow over time. As a result, spacecraft in these Lagrangian point orbits must use their propulsion systems to perform orbital station-keeping. Although they are not perfectly stable, a modest effort of station keeping keeps a spacecraft in a desired Lissajous orbit for a long time. In the absence of other influences, orbits about Lagrangian points L4 and L5 are dynamically stable so long as the ratio of the masses of the two main objects is greater than about 25. The natural dynamics keep the spacecraft (or natural celestial body) in the vicinity of the Lagrangian point without use of a propulsion system, even when slightly perturbed from equilibrium. These orbits can however be destabilized by other nearby massive objects. For example, orbits around the L4 and L5 points in the Earth–Moon system can last only a few million years instead of billions because of perturbations by the other planets in the Solar System. == Spacecraft using Lissajous orbits == Several missions have used Lissajous orbits: ACE at Sun–Earth L1, SOHO at Sun–Earth L1, DSCOVR at Sun–Earth L1, WMAP at Sun–Earth L2, and also the Genesis mission collecting solar particles at
|
{
"page_id": 10228498,
"source": null,
"title": "Lissajous orbit"
}
|
L1. On 14 May 2009, the European Space Agency (ESA) launched into space the Herschel and Planck observatories, both of which use Lissajous orbits at Sun–Earth L2. ESA's Gaia mission also uses a Lissajous orbit at Sun–Earth L2. In 2011, NASA transferred two of its THEMIS spacecraft from Earth orbit to Lunar orbit by way of Earth–Moon L1 and L2 Lissajous orbits. In June 2018, Queqiao, the relay satellite for China's Chang'e 4 lunar lander mission, entered orbit around Earth-Moon L2. == Fictional appearances == In the 2005 science fiction novel Sunstorm by Arthur C. Clarke and Stephen Baxter, a huge shield is constructed in space to protect the Earth from a deadly solar storm. The shield is described to have been in a Lissajous orbit at L1. In the story a group of wealthy and powerful people shelter opposite the shield at L2 so as to be protected from the solar storm by the shield, the Earth and the Moon. In the 2017 science fiction novel Artemis by Andy Weir, a Lissajous orbit is used as a transfer point for routine travel to and from the Moon. == See also == Libration point orbit == Notes == == References == == External links == Koon, W. S.; M. W. Lo; J. E. Marsden; S. D. Ross (2006). Dynamical Systems, the Three-Body Problem, and Space Mission Design. Archived (PDF) from the original on March 2, 2020. Koon, Wang Sang; et al. (2000). "Dynamical Systems, the Three-Body Problem, and Space Mission Design" (PDF). International Conference on Differential Equations. Berlin: World Scientific. pp. 1167–1181.
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{
"page_id": 10228498,
"source": null,
"title": "Lissajous orbit"
}
|
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