text stringlengths 11 320k | source stringlengths 26 161 |
|---|---|
Georg Friedrich von Reichenbach (24 August 1771 – 21 May 1826) was a German scientific instrument maker.
Reichenbach's father was a master mechanic, and a master cannon-borer, who moved to Mannheim when Reichenbach was two, and became manager of the cannon-boring works there. At 14 Georg was admitted to the Military School at Mannheim where he got to know the astronomer at the Mannheim Observatory. He received a knowledge of mathematical instruments and was inspired to try to construct similar instruments in his father's workshop. The Director of the Observatory sent a sextant made by Reichenbach to Count Rumford .
When he was 19, Reichenbach received a grant of 500 gulden for a journey to London, and introductions to the engineers James Watt and Matthew Boulton . Reichenbach's first visit to England lasted from 1 June 1791 to January 1792, when he returned home for a short time before returning to England. He made drawings of Watt's steam engine despite Watt's attempts to keep it secret from him and also worked as an engineer in English ironworks and studied English instrument making.
He returned home in May 1793 and attempted improvements in the military workshops in Mannheim and Munich, with the help of his father.
In 1796 he moved to Munich where he began making his famous scientific instruments, including a dividing engine , in between carrying out military work, which included the invention of a breech-loading rifle which however did not prove popular.
In 1804, with Joseph Liebherr and Joseph Utzschneider , he founded an instrument making business in Munich and from 1807 onwards he was occupied more and more with the technical problems involved in making scientific instruments, in 1809 establishing with Joseph Fraunhofer and Utzschneider, optical works at Benediktbeuern , which were later moved to Munich in 1823. [ 1 ]
In 1811 resigned from the army to devote his time to his scientific work and in 1814 withdrew from both of the companies he had been involved with, founding with T. L. Ertel a new optical business, from which he retired in 1821, when he obtained an engineering appointment under the Bavarian government. He died at Munich on 21 May 1826. [ 1 ] He is buried in the Alter Südfriedhof in Munich.
Reichenbach's principal achievement was the introduction into observatories of the meridian or transit circle , which combined the transit and the mural circle into one instrument. This had already been done by Ole Rømer in around 1704, but the idea had not been adopted by anyone else, except in the transit circle constructed by Edward Troughton for Stephen Groombridge in 1806. The transit circle in the form given it by Reichenbach had one finely divided circle attached to one end of the horizontal axis and was read by four verniers on an " alidade circle," the unaltered position of which was tested by a spirit level. The instrument came almost at once into universal use on the continent of Europe (the first one was made for F. W. Bessel in 1819), but in England the mural circle and transit instrument were not superseded for many years. [ 1 ] | https://en.wikipedia.org/wiki/Georg_Friedrich_von_Reichenbach |
Georg Limnaeus (born Georg Wirn , also known as Georgius Lymneus , Limnæus or Limnäus ; 24 October 1554 – 14 September 1611) was a German mathematician, astronomer and librarian, who provided noteworthy encouragement to Johannes Kepler shortly after his first heliocentric astronomical work was published. [ 1 ]
Georg Limnaeus' father Antonius Wirn originated from Switzerland and served in the military forces of Frederick I, Elector of Saxony , who had been tutored by George Spalatin and closely followed and supported the works of Martin Luther . Around the time of the Capitulation of Wittenberg , Frederick conceived of the founding of the University of Jena , which was established in 1558 and became the university where Limnaeus was to spend all of his academic years. [ 2 ]
Upon completion of his military service, Antonius moved to Jena, where Georg Wirn was born and lived, and where, in 1571, he enrolled at the university. In accordance with its tradition, upon enrollment he assumed the name Georgius Lymneus. At Jena, Limnaeus studied under Jacob Flach (1537–1611), who was a graduate of the University of Wittenberg and had exposure to Philip Melanchthon (1497–1569) and frequented the lectures of Erasmus Reinhold (1511–1553.) [ 3 ]
In 1581, Limnaeus received the "Magisters der Philosophie" degree at the University of Jena.
Limnaeus issued a prognostication in 1585 in Erfurt and, in 1588, became the professor of mathematics at Jena, a position which he held until his death; concurrently, he also assumed the position of head librarian. He lectured on the Celestial sphere , astronomical and scientific calculations, the theory of planets and the use of astronomical tables, and in the areas of geography, geodesy and cosmography. Although he was not known to have produced any memorable manuscripts, he is known to have engaged in professional correspondence with peers, from time to time, including Tycho Brahe , Galileo Galilei , and Johannes Kepler, and to have maintained a respectable reputation as an academic prognosticator. In 1596, he founded the first observatory in Jena. [ 4 ]
In 1597, Limnaeus (along with Galileo, Brahe and Ursus ) received a draft copy from Kepler of his first major work, Mysterium Cosmographicum . On April 24, 1598, Limnaeus wrote to Kepler, expressing his firm belief that heliocentric considerations should not be dismissed from the studies of astronomy by declaring, "Most illustrious Sir, never was I estranged from the most ancient philosophy of the Platonists – nor have I thought, as have several petty philosophers in our time, that it ought to be shunted outside the borders of the territory of the republic of letters." These words have been used to illustrate that it was not uncommon for traditionalist academicians, such as Limnaeus, to covertly honor heliocentric views of the ancients, while at the same time skillfully avoiding any explicit reference to the more controversial views of Copernicus. Limnaeus added, however, the statement that for any serious student of astronomy, Kepler's work represents "a new path to knowledge of the stars." In light of the disconcerting imprisonment of Giordano Bruno in 1593 (who was executed in 1600), this open expression of both support to young Kepler, and delight in his mathematical astronomical approaches, provided him with some of the earliest, forceful words of encouragement, which he must have welcomed in contrast to the many strong criticisms his work quickly evoked. [ 5 ]
In addition, Limnaeus provided information to Kepler on Tycho Brahe which may have promoted his final decision to go to Prague and study under him, thereby ensuring access to Brahe's data and the furtherance of his own work. However, beyond serving as an encourager to Kepler, and a facilitator to his decision to assist Brahe, there is no record that Limnaeus ever dove into specific details of Kepler's work or adopted it for his lessons. [ 6 ]
Kepler assisted Brahe from 1599 until Brahe's sudden death in 1601. By 1609, Kepler would develop and introduce his laws of planetary motion, which would subsequently play a major role in the development of Isaac Newton 's law of universal gravitation, as has been noted by Newton.
Limnaeus and his wife fell victim to the 1611 plague in Jena. [ citation needed ] | https://en.wikipedia.org/wiki/Georg_Limnaeus |
Georg Thomas Sabler ( Russian : Его́р Его́рович Са́блер or Георг Заблер , Lithuanian : Georgas Tomas Sableris ; 30 April [ O.S. 18 April] 1810 – 7 December 1865) was an astronomer and geodesist of Baltic German origin active in territories of modern-day Estonia, Lithuania, Ukraine, and Russia (then all part of the Russian Empire ).
A student of Friedrich Georg Wilhelm von Struve , Sabler studied theology and mathematics at the University of Tartu . Fascinated by Struve's lectures of astronomy, Sabler participated in an expedition that measured the difference of sea levels in the Black Sea and Caspian Sea . Sabler then worked as an astronomer at Tartu Observatory and Pulkovo Observatory , and later became the director of the Vilnius University Astronomical Observatory , which received its own photoheliograph due to Sabler's efforts. The telescope was the second one produced in the world. Sabler and his assistant Matvey Gusev pioneered the photography and research of sunspots.
He was described as the "creator and pioneer of new astrophysical research at the Vilnius observatory". Sabler also constructed a star catalog, took care of the methodology of observations, and constructed various astronomical instruments such as achromatic lenses . Notably, Sabler participated in determining the Struve Geodetic Arc in Finland, Lithuania, Ukraine, and Bessarabia . Sabler was the first to find a way to determine the angle of refraction in transparent media.
Georg Thomas Sabler was born on 30 April [ O.S. 18 April] 1810 in Haljala , now part of Lääne-Viru County , Estonia. His father, Georg Christian Sabler (1776–1819), was a Lutheran pastor. [ 1 ] At first, Sabler studied privately. Later, Sabler graduated from the Tartu Evangelical Cathedral's gymnasium. [ 2 ] Sabler studied theology (1828–1832) and mathematics (1832–1839) at the University of Tartu . He developed an interest in natural sciences, especially in astronomy, which was lectured by Friedrich Georg Wilhelm von Struve . During his study years, Sabler was engaged in astronomical observations, particularly of binary stars . [ 3 ] Some of his works were published in the scientific press. For his scientific aptitude, von Struve ensured that Sabler began working at the Tartu Observatory as an assistant to its director until 1839. [ 4 ]
In 1836–1837 Sabler participated in an expedition that determined the difference between the sea levels of the Black Sea and Caspian Sea . [ 3 ] He also edited the material collected during the expedition and published it in German under the title "Beschreibung der zur Ermittelung des Höhenunterschiedes zwischen dem Schwarzen und dem Caspischen Meere... in den Jahren 1836 und 1837 von Gr. Fuss, A. Sawitsch und G. Sabler ausgeführten Messungen... zusammengestellt von G. Sabler. Im Auftrage der Akademie herausgegeben von W. Struve" . For his work, which he wrote about in 1839, he received a doctoral degree , and subsequently graduated that same year. [ 4 ]
From 1839 to 1854 Sabler worked as an assistant and senior astronomer at the Pulkovo Observatory near St. Petersburg , where Struve was the director. Actively partaking in astronomical research, Sabler was then assigned the task of measuring the exact coordinates of stars using a large meridian circle . From 1844 to 1853, Sabler and Carl Friedrich Tenner participated in the construction of the Struve Geodetic Arc in modern-day Finland, Bessarabia , and Ukraine. [ 4 ] In Ukraine, specifically the Khotynsky district , the scientists chose the prevailing heights of the area, which were located near the villages of Romankivtsi, Shebutyntsi, Selishche, and Hrubno. Sabler lived in Romankivtsi for more than a week. The results of the research were published in the bulletin of the Imperial Russian Geographical Society , the journal of the Ministry of National Education , and others. [ 2 ]
Sabler also participated in measuring the longitude difference between the Pulkovo Observatory and Altona Observatory . [ 2 ] In his free time, Sabler polished lenses, successfully making quality achromatic lenses using two glasses of crown glass between which lay a transparent liquid with the appropriate refractive and light scattering coefficients. [ 2 ] The lenses were described in the St. Petersburg Academy of Sciences 's newsletter. One of Sabler's prism lenses has survived to this day and is an exhibition in the Vilnius University Science Museum. [ 4 ]
After coming to Vilnius , Sabler determined the geographical position of one of the points used for measuring the Struve Geodetic Arc near the village of Nemėžis . [ 3 ] From 1854 to 1865, Sabler was director of the Vilnius University Astronomical Observatory . [ 5 ] Sabler sent his assistant and fellow astronomer Matvey Gusev for an internship to England in 1858–1860, where they learned of the appliance of photography in astronomy in Kew Observatory , famously pioneered by astronomer Warren De la Rue . On 19 April 1861, Sabler participated in a meeting hosted by the St. Petersburg Academy of Sciences' physics and mathematics department in Pulkovo. In the meeting, Sabler argued that the university's observatory required a solar telescope , emphasizing that the observatory should direct all efforts for astrophysics research of sunspots and star photometry instead of traditional astrometry . [ 4 ]
In 1862–1864, while in Great Britain , Sabler observed the development of the solar telescope. [ 3 ] He successfully ordered one of the solar telescopes after negotiations with John Henry Dallmeyer [ 2 ] and permission from Struve. In 1864, the Vilnius observatory successfully received its own solar telescope and produced one of the first pictures of sunspots. [ 3 ] The telescope would be destroyed in a fire in 1876. Sabler used a method of coating the photographic plate with collodion, which was a method invented in 1850. Firstly, the glass would be filled with a nitrocellulose solution enriched with iodides and bromides and dried. Before photographing, the plate would be further sensitized by dipping it in a solution of silver nitrate and silver iodide. The prepared photographic plate had to be exposed for 10 or 15 minutes and developed immediately. [ 4 ]
The establishment of a new solar telescope meant a reconstruction of the observatory's towers. However, as Sabler became increasingly sick, he made Gusev responsible for the continuation of his works. Sabler traveled to St. Petersburg for treatment, after which he became less ill, but only for a short time. In autumn of 1865 the illness, which was a brain tumor , began to rapidly progress. Sabler's scientific work continued to be worked upon in the observatory by Gusev and Pyotr Smyslov . [ 4 ]
Sabler died on 7 December 1865 in Vilnius . [ 6 ] He was buried in the Vilnius Evangelical Lutheran Cemetery. The grave was destroyed during the Soviet occupation of Lithuania. [ 4 ]
A commemorative plaque was uncovered in his home village of Haljala on 24 June 1991. [ 7 ] | https://en.wikipedia.org/wiki/Georg_Thomas_Sabler |
Georg Jacob Tysland (13 February 1890 – 14 February 1932) was a Norwegian engineer and metallurgist. Tysland is known as the originator of a successful electric smelting furnace for the production of pig iron , a semi-finished product for the production of steel. [ 1 ]
He was born in Kristiania (now Oslo), Norway. He was a son of colonel Lars Jørgen Tysland (1848–1911) and Marie Cathrine Sandberg (1862–1942). He was a maternal grandson of military officer Ole Rømer Sandberg (1831–1899) and cousin of legislator Ole Rømer Aagaard Sandberg (1900–1985) . [ 2 ]
He grew up in Kristiania and Bergen, and graduated from Bergen tekniske skole in 1908 before finishing his secondary education at Bergen Cathedral School in 1910. He graduated from the University of Liège in Belgium during 1913. [ 2 ]
He was a manager at Tinfos Jernverk in Notodden from 1913 to 1916, and then spent half a year in the United States, a stay interrupted by rheumatic fever . Back in Norway he established Skaland Grafittverk in Senja during 1918, was hired in the Ministry of Trade in 1921 and then in Fiskaa Verk in Kristiansand during 1922.
He was next hired to experiment with new electric smelting furnaces. The Tysland-Hole Furnace ( Tysland-Hole-ovnen ) was first erected at Christiania Spigerverk in 1928 and was put on use in 1929. The Tysland-Hole furnace was developed by Tysland jointly with engineer Ivar Hole (1882–1939). Railway rails and reinforcing steel become main products produced. [ 3 ]
Tysland worked at Christiania Spigerverk from 1924 to 1927, Bremanger Smelteverk in Svelgen from 1927 to 1931, then Skaland Grafittverk in Skaland from 1931 to his death from heart failure. [ 4 ] [ 2 ]
This Norwegian business biographical article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Georg_Tysland |
Georg Wittig ( German: [ˈɡeː.ɔʁk ˈvɪ.tɪç] ⓘ ; 16 June 1897 – 26 August 1987) was a German chemist who reported a method for synthesis of alkenes from aldehydes and ketones using compounds called phosphonium ylides in the Wittig reaction . He shared the Nobel Prize in Chemistry with Herbert C. Brown in 1979.
Wittig was born in Berlin, Germany ; shortly after his birth moved with his family to Kassel , where his father was professor at the applied arts high school. He attended school in Kassel and started studying chemistry at the University of Tübingen 1916. He was drafted and became a lieutenant in the cavalry of Hesse-Kassel (or Hesse-Cassel). After being an Allied prisoner of war from 1918 until 1919, Wittig found it hard to restart his chemistry studies owing to overcrowding at the universities. By a direct plea to Karl von Auwers , who was professor for organic chemistry at the University of Marburg at the time, he was able to resume university study and after three years was awarded the Ph.D. in organic chemistry.
Karl von Auwers was able to convince him to start an academic career, leading to his habilitation in 1926. He became a close friend of Karl Ziegler , who was also doing his habilitation with Auwers during that time. The successor of Karl von Auwers , Hans Meerwein , accepted Wittig as lecturer, partly because he was impressed by the new 400-page book on stereochemistry that Wittig had written. In 1931 Wittig married Waltraud Ernst, a colleague from the Auwers working group. The invitation of Karl Fries brought him as professor to the TU Braunschweig in 1932. The time in Braunschweig became more and more problematic as the Nazis tried to get rid of Karl Fries and Wittig showed solidarity with him. After the forced retirement of Fries, in 1937 Hermann Staudinger offered Wittig a position at the University of Freiburg , partly because he knew Wittig from his book on stereochemistry in which he supported Staudinger's highly criticized theory of macromolecules. The foundations of carbanion chemistry were laid during Wittig's time in Freiburg.
In 1944 he succeeded the head of the organic chemistry department Wilhelm Schlenk at the University of Tübingen . Most of his scientific work, including the development of the Wittig reaction , was performed during this time in Tübingen. The 1956 appointment of the nearly sixty-year-old Wittig as head of the organic chemistry department at the University of Heidelberg as successor of Karl Freudenberg was exceptional even at that time. The newly built department and the close connection to the BASF convinced Wittig to take this opportunity. He worked at the University of Heidelberg even after his retirement in 1967 and published papers until 1980. Most of his awards were presented during this time at Heidelberg, such as the honorary doctorate of the Sorbonne in 1956 and the Nobel Prize in Chemistry in 1979.
Wittig's contributions also include the preparation of phenyllithium and the discovery of the 1,2-Wittig rearrangement and the 2,3-Wittig rearrangement .
Wittig was well known in the chemistry community for being a consummate experimenter and observer of chemical transformations, while caring very little for the theoretical and mechanistic underpinnings of the work he produced.
Georg also has his name on a literature work titled on a compound labelled Colopidalol . [ 1 ] | https://en.wikipedia.org/wiki/Georg_Wittig |
George Berkeley ( / ˈ b ɑːr k l i / BARK -lee ; [ 5 ] [ 6 ] 12 March 1685 – 14 January 1753), known as Bishop Berkeley ( Bishop of Cloyne of the Anglican Church of Ireland ), was an Anglo-Irish philosopher, writer, and clergyman who is regarded as the founder of "immaterialism", a philosophical theory he developed which was later referred to as " subjective idealism " by others. As a leading figure in the empiricism movement, he was one of the most cited philosophers of 18th-century Europe , [ 7 ] and his works had a profound influence on the views of other thinkers, especially Immanuel Kant and David Hume . [ 8 ] Interest in his ideas increased significantly in the United States during the early 19th century, and as a result, the University of California, Berkeley , as well as the city of Berkeley, California , were both named after him.
In 1709, Berkeley published his first major work An Essay Towards a New Theory of Vision , in which he discussed the limitations of human vision and advanced the theory that the proper objects of sight are not material objects, but light and colour. [ 9 ] This foreshadowed his most well-known philosophical work A Treatise Concerning the Principles of Human Knowledge , published in 1710, which, after its poor reception, he rewrote in dialogue form and published under the title Three Dialogues Between Hylas and Philonous in 1713. [ 10 ] In this book, Berkeley's views were represented by Philonous (Greek: "lover of mind"), while Hylas (" hyle ", Greek: "matter") embodies Berkeley's opponents, in particular John Locke .
Berkeley argued against Isaac Newton 's doctrine of absolute space, time and motion in De Motu [ 11 ] ( On Motion ), first published in 1721. His arguments were a notable precursor to those of Ernst Mach and Albert Einstein . [ 12 ] [ 13 ] In 1732, he published Alciphron , a Christian apologetic against the free-thinkers , and in 1734, he published The Analyst , a critique of the foundations of calculus , which was influential in the development of mathematics. [ 14 ] In his work on immaterialism, Berkeley's theory denies the existence of material substance and instead contends that familiar objects like tables and chairs are ideas perceived by the mind and, as a result, cannot exist without being perceived. Berkeley is also known for his critique of abstraction , an important premise in his argument for immaterialism. [ 15 ]
Interest in Berkeley's work increased greatly after World War II because he tackled many of the issues of paramount interest to philosophy in the 20th century, such as the problems of perception, the difference between primary and secondary qualities, and the importance of language. [ 16 ]
Berkeley was born at his family home, Dysart Castle , near Thomastown , County Kilkenny , Ireland, the eldest son of William Berkeley, a cadet of the noble family of Berkeley whose ancestry can be traced back to the Anglo-Saxon period and who had served as feudal lords and landowners in Gloucester , England. [ 17 ] [ 18 ] Little is known of his mother. He was educated at Kilkenny College and attended Trinity College Dublin , where he was elected a Scholar in 1702, being awarded BA in 1704 and MA and a Fellowship in 1707. He remained at Trinity College after the completion of his degree as a tutor and Greek lecturer.
His earliest publication was on mathematics, but the first that brought him notice was his An Essay towards a New Theory of Vision , first published in 1709. In the essay, Berkeley examines visual distance, magnitude, position and problems of sight and touch. While this work raised much controversy at the time, its conclusions are now accepted as an established part of the theory of optics.
The next publication to appear was the Treatise Concerning the Principles of Human Knowledge in 1710, which had great success and gave him a lasting reputation, though few accepted his theory that nothing exists outside the mind. This was followed in 1713 by Three Dialogues Between Hylas and Philonous , in which he propounded his system of philosophy, the leading principle of which is that the world, as represented by our senses, depends for its existence on being perceived.
For this theory, the Principles gives the exposition and the Dialogues the defence. One of his main objectives was to combat the prevailing materialism of his time. The theory was largely received with ridicule, while even those such as Samuel Clarke and William Whiston , who did acknowledge his "extraordinary genius," were nevertheless convinced that his first principles were false.
Shortly afterwards, Berkeley visited England and was received into the circle of Addison , Pope and Steele . In the period between 1714 and 1720, he interspersed his academic endeavours with periods of extensive travel in Europe, including one of the most extensive Grand Tours of the length and breadth of Italy ever undertaken. [ 19 ] In 1721, he took Holy orders in the Church of Ireland , earning his doctorate in divinity , and once again chose to remain at Trinity College Dublin, lecturing this time in Divinity and in Hebrew . In 1721/2 he was made Dean of Dromore and, in 1724, Dean of Derry .
In 1723, Berkeley was named co-heir of Esther Vanhomrigh , along with the barrister Robert Marshall . This naming followed Vanhomrigh's violent quarrel with Jonathan Swift , who had been her intimate friend for many years. Vanhomrigh's choice of legatees caused a good deal of surprise since she did not know either of them well, although Berkeley as a very young man had known her father. Swift said that he did not grudge Berkeley his inheritance, much of which vanished in a lawsuit in any event. A story that Berkeley and Marshall disregarded a condition of the inheritance that they must publish the correspondence between Swift and Vanessa is probably untrue.
In 1725, Berkeley began the project of founding a college in Bermuda for training ministers and missionaries in the colony, in pursuit of which he gave up his deanery with its income of £1,100.
On 1 August 1728 at St Mary le Strand , London, [ 20 ] Berkeley married Anne Forster, daughter of John Forster , Chief Justice of the Irish Common Pleas , and Forster's first wife Rebecca Monck. He then went to America on a salary of £100 per annum. He landed near Newport, Rhode Island , where he bought a plantation at Middletown – the famous " Whitehall ". Berkeley purchased several enslaved Africans to work on the plantation. [ 21 ] [ 22 ] In 2023, Trinity College Dublin removed Berkeley's name from one of its libraries because of his slave ownership and his active defence of slavery. [ 23 ]
It has been claimed that "he introduced Palladianism into America by borrowing a design from [William] Kent's Designs of Inigo Jones for the door-case of his house in Rhode Island, Whitehall". [ 24 ] He also brought to New England John Smibert , the Scottish artist he "discovered" in Italy, who is generally regarded as the founding father of American portrait painting. [ 25 ] Meanwhile, he drew up plans for the ideal city he planned to build on Bermuda. [ 26 ] He lived at the plantation while he waited for funds for his college to arrive. The funds, however, were not forthcoming. "With the withdrawal from London of his own persuasive energies, opposition gathered force; and the Prime Minister, Walpole grew steadily more sceptical and lukewarm. At last it became clear that the essential Parliamentary grant would be not forthcoming", [ 27 ] and in 1732 he left America and returned to London.
He and Anne had four children who survived infancy – Henry, George, William and Julia – and at least two others who did not. William's death in 1751 was a great cause of grief for his father.
Berkeley was nominated to be the Bishop of Cloyne in the Church of Ireland on 18 January 1734. He was consecrated as such on 19 May 1734. He was the Bishop of Cloyne until his death on 14 January 1753, although he died at Oxford (see below).
While living in London's Saville Street, he took part in efforts to create a home for the city's abandoned children. The Foundling Hospital was founded by royal charter in 1739, and Berkeley is listed as one of its original governors.
His last two publications were Siris: A Chain of Philosophical Reflexions and Inquiries Concerning the Virtues of Tarwater, And divers other Subjects connected together and arising one from another (1744) and Further Thoughts on Tar-water (1752). Pine tar is an effective antiseptic and disinfectant when applied to cuts on the skin, but Berkeley argued for the use of pine tar as a broad panacea for diseases. His 1744 work on tar-water sold more copies than any of his other books during Berkeley's lifetime. [ 28 ]
He remained at Cloyne until 1752, when he retired. With his wife and daughter Julia, he went to Oxford to live with his son George and supervise his education. [ 29 ] He died soon afterwards and was buried in Christ Church Cathedral, Oxford . His affectionate disposition and genial manners made him much loved and held in warm regard by many of his contemporaries. Anne outlived her husband by many years, and died in 1786. [ 30 ]
According to Berkeley there are only two kinds of things: spirits and ideas. Spirits are simple, active beings which produce and perceive ideas; ideas are passive beings which are produced and perceived. [ 31 ]
The use of the concepts of "spirit" and "idea" is central in Berkeley's philosophy. As used by him, these concepts are difficult to translate into modern terminology. His concept of "spirit" is close to the concept of "conscious subject" or of "mind", and the concept of "idea" is close to the concept of "sensation" or "state of mind" or "conscious experience".
Thus Berkeley denied the existence of matter as a metaphysical substance, but did not deny the existence of physical objects such as apples or mountains ("I do not argue against the existence of any one thing that we can apprehend, either by sense or reflection. That the things I see with mine eyes and touch with my hands do exist, really exist, I make not the least question. The only thing whose existence we deny, is that which philosophers call matter or corporeal substance. And in doing of this, there is no damage done to the rest of mankind, who, I dare say, will never miss it.", Principles #35). This basic claim of Berkeley's thought, his "idealism", is sometimes and somewhat derisively called "immaterialism" or, occasionally, subjective idealism . In Principles #3, he wrote, using a combination of Latin and English, esse is percipi (to be is to be perceived), most often if slightly inaccurately attributed to Berkeley as the pure Latin phrase esse est percipi . [ 32 ] The phrase appears associated with him in authoritative philosophical sources, e.g., "Berkeley holds that there are no such mind-independent things, that, in the famous phrase, esse est percipi (aut percipere) —to be is to be perceived (or to perceive)." [ 28 ]
Hence, human knowledge is reduced to two elements: that of spirits and of ideas ( Principles #86). In contrast to ideas, a spirit cannot be perceived. A person's spirit, which perceives ideas, is to be comprehended intuitively by inward feeling or reflection ( Principles #89). For Berkeley, we have no direct 'idea' of spirits, albeit we have good reason to believe in the existence of other spirits, for their existence explains the purposeful regularities we find in experience [ 33 ] ("It is plain that we cannot know the existence of other spirits otherwise than by their operations, or the ideas by them excited in us", Dialogues #145). This is the solution that Berkeley offers to the problem of other minds . Finally, the order and purposefulness of the whole of our experience of the world and especially of nature overwhelms us into believing in the existence of an extremely powerful and intelligent spirit that causes that order. According to Berkeley, reflection on the attributes of that external spirit leads us to identify it with God. Thus a material thing such as an apple consists of a collection of ideas (shape, colour, taste, physical properties, etc.) which are caused in the spirits of humans by the spirit of God.
A convinced adherent of Christianity, Berkeley believed God to be present as an immediate cause of all our experiences.
He did not evade the question of the external source of the diversity of the sense data at the disposal of the human individual. He strove simply to show that the causes of sensations could not be things, because what we called things, and considered without grounds to be something different from our sensations, were built up wholly from sensations. There must consequently be some other external source of the inexhaustible diversity of sensations. The source of our sensations, Berkeley concluded, could only be God; He gave them to man, who had to see in them signs and symbols that carried God's word. [ 34 ]
Here is Berkeley's proof of the existence of God:
Whatever power I may have over my own thoughts, I find the ideas actually perceived by Sense have not a like dependence on my will . When in broad daylight I open my eyes, it is not in my power to choose whether I shall see or no, or to determine what particular objects shall present themselves to my view; and so likewise as to the hearing and other senses; the ideas imprinted on them are not creatures of my will. There is therefore some other Will or Spirit that produces them. (Berkeley. Principles #29)
As T. I. Oizerman explained:
Berkeley's mystic idealism (as Kant aptly christened it) claimed that nothing separated man and God (except materialist misconceptions, of course), since nature or matter did not exist as a reality independent of consciousness. The revelation of God was directly accessible to man, according to this doctrine; it was the sense-perceived world, the world of man's sensations, which came to him from on high for him to decipher and so grasp the divine purpose. [ 34 ]
Berkeley believed that God is not the distant engineer of Newtonian machinery that in the fullness of time led to the growth of a tree in the university quadrangle. Rather, the perception of the tree is an idea that God's mind has produced in the mind, and the tree continues to exist in the quadrangle when "nobody" is there, simply because God is an infinite mind that perceives all.
The philosophy of David Hume concerning causality and objectivity is an elaboration of another aspect of Berkeley's philosophy. A.A. Luce , the most eminent Berkeley scholar of the 20th century, constantly stressed the continuity of Berkeley's philosophy. The fact that Berkeley returned to his major works throughout his life, issuing revised editions with only minor changes, also counts against any theory that attributes to him a significant volte-face. [ 35 ]
Yet as Colin Murray Turbayne observed, late entries found amidst Berkeley's unpublished private notes in the Philosophical Commentaries point toward his inclination to withdraw from a dogmatic form of ontological idealism in order to adopt a more skeptical attitude toward the existence of an active, universal substantial mind such as God. [ 36 ] Here, Berkeley's "official doctrine" that "Mind is a substance." in a literal sense is accompanied by additional puzzling references to a universal "thinking substance, something unknown" (687) and "the substance of Spirit we do not know, it not being knowable" (701). In his exegesis of the term "substance", and his description of the soul as a substance in which ideas "inhere" while it "supports" ideas, Berkeley also asserts that he must "use utmost caution not to give give the least handle of offense to the Church or Church-men (715)". [ 37 ] Keeping in mind Berkeley's development of a philosophy of science and his theory of vision, this suggests that his final references to God as a universal and "substantial mind" are essentially metaphorical in nature and indicate a willingness to diplomatically uphold a "purely substantivalist conception of the mind, confirmed by his private utterances". [ 38 ]
John Locke (Berkeley's intellectual predecessor) states that we define an object by its primary and secondary qualities . He takes heat as an example of a secondary quality. If you put one hand in a bucket of cold water, and the other hand in a bucket of warm water, then put both hands in a bucket of lukewarm water, one of your hands is going to tell you that the water is cold and the other that the water is hot. Locke says that since two different objects (both your hands) perceive the water to be hot and cold, then the heat is not a quality of the water.
While Locke used this argument to distinguish primary from secondary qualities, Berkeley extends it to cover primary qualities in the same way. For example, he says that size is not a quality of an object because the size of the object depends on the distance between the observer and the object, or the size of the observer. Since an object is a different size to different observers, then size is not a quality of the object. Berkeley rejects shape with a similar argument and then asks: if neither primary qualities nor secondary qualities are of the object, then how can we say that there is anything more than the qualities we observe? [ clarification needed ]
Relativity is the idea that there is no objective, universal truth; it is a state of dependence in which the existence of one independent object is solely dependent on that of another. According to Locke, characteristics of primary qualities are mind-independent, such as shape, size, etc., whereas secondary qualities are mind-dependent, for example, taste and colour. George Berkeley refuted John Locke's belief on primary and secondary qualities because Berkeley believed that "we cannot abstract the primary qualities (e.g shape) from secondary ones (e.g colour)". [ 39 ] Berkeley argued that perception is dependent on the distance between the observer and the object, and "thus, we cannot conceive of mechanist material bodies which are extended but not (in themselves) colored". [ 39 ] What perceived can be the same type of quality, but completely opposite from each other because of different positions and perceptions, what we perceive can be different even when the same types of things consist of contrary qualities. Secondary qualities aid in people's conception of primary qualities in an object, like how the colour of an object leads people to recognize the object itself. More specifically, the colour red can be perceived in apples, strawberries, and tomatoes, yet we would not know what these might look like without its colour. We would also be unaware of what the colour red looked like if red paint, or any object that has a perceived red colour, failed to exist. From this, we can see that colours cannot exist on their own and can solely represent a group of perceived objects. Therefore, both primary and secondary qualities are mind-dependent: they cannot exist without our minds.
George Berkeley was a philosopher who opposed rationalism and "classical" empiricism . He was a " subjective idealist " or "empirical idealist", who believed that reality is constructed entirely of immaterial, conscious minds and their ideas; everything that exists is somehow dependent on the subject perceiving it, except the subject themselves. He refuted the existence of abstract objects that many other philosophers believed to exist, notably Plato. According to Berkeley, "an abstract object does not exist in space or time and which is therefore entirely non-physical and non-mental"; [ 40 ] however, this argument contradicts his relativity argument. If "esse est percipi", [ 41 ] (Latin meaning that to exist is to be perceived) is true, then the objects in the relativity argument made by Berkeley can either exist or not. Berkeley believed that only the minds' perceptions and the Spirit that perceives are what exists in reality; what people perceive every day is only the idea of an object's existence, but the objects themselves are not perceived. Berkeley also discussed how, at times, materials cannot be perceived by oneself, and the mind of oneself cannot understand the objects. However, there also exists an "omnipresent, eternal mind" [ 42 ] that Berkeley believed to consist of God and the Spirit, both omniscient and all-perceiving. According to Berkeley, God is the entity who controls everything, yet Berkeley also argued that "abstract object[s] do not exist in space or time". [ 40 ] In other words, as Warnock argues, Berkeley "had recognized that he could not square with his own talk of spirits , of our minds and of God; for these are perceivers and not among objects of perception. Thus he says, rather weakly and without elucidation, that in addition to our ideas, we also have notions —we know what it means to speak of spirits and their operations." [ 43 ]
However, the relativity argument violates the idea of immaterialism. Berkeley's immaterialism argues that "esse est percipi (aut percipere)", [ 44 ] which in English is: to be is to be perceived (or to perceive). That is saying only what is perceived or perceived is real, and without our perception or God's nothing can be real. Yet, if the relativity argument, also by Berkeley, argues that the perception of an object depends on the different positions, then this means that what is perceived can either be real or not because the perception does not show that whole picture and the whole picture cannot be perceived. Berkeley also believes that "when one perceives mediately, one perceives one idea by means of perceiving another". [ 45 ] By this, it can be elaborated that if the standards of what perceived at first are different, what perceived after that can be different, as well. In the heat perception described above, one hand perceived the water to be hot and the other hand perceived the water to be cold due to relativity. If applying the idea "to be is to be perceived", the water should be both cold and hot because both perceptions are perceived by different hands. However, the water cannot be cold and hot at the same time for it self-contradicts, so this shows that what perceived is not always true because it sometimes can break the law of noncontradiction. In this case, "it would be arbitrary anthropocentrism to claim that humans have special access to the true qualities of objects". [ 4 ] The truth for different people can be different, and humans are limited to accessing the absolute truth due to relativity. Summing up, nothing can be absolutely true due to relativity or the two arguments, to be is to be perceived and the relativity argument, do not always work together.
In his Essay Towards a New Theory of Vision , Berkeley frequently criticised the views of the Optic Writers, a title that seems to include Molyneux , Wallis, Malebranche and Descartes . [ 46 ] In sections 1–51, Berkeley argued against the classical scholars of optics by holding that: spatial depth, as the distance that separates the perceiver from the perceived object is itself invisible . That is, we do not see space directly or deduce its form logically using the laws of optics. Space for Berkeley is no more than a contingent expectation that visual and tactile sensations will follow one another in regular sequences that we come to expect through habit.
Berkeley goes on to argue that visual cues, such as the perceived extension or 'confusion' of an object, can only be used to indirectly judge distance, because the viewer learns to associate visual cues with tactile sensations. Berkeley gives the following analogy regarding indirect distance perception: one perceives distance indirectly just as one perceives a person's embarrassment indirectly. When looking at an embarrassed person, we infer indirectly that the person is embarrassed by observing the red colour on the person's face. We know through experience that a red face tends to signal embarrassment, as we've learned to associate the two.
The question concerning the visibility of space was central to the Renaissance perspective tradition and its reliance on classical optics in the development of pictorial representations of spatial depth. This matter has been debated by scholars since the 11th-century Arab polymath and mathematician Alhazen (Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham) affirmed in experimental contexts the visibility of space. This issue, which was raised in Berkeley's theory of vision, was treated at length in the Phenomenology of Perception of Maurice Merleau-Ponty , in the context of confirming the visual perception of spatial depth ( la profondeur ), and by way of refuting Berkeley's thesis. [ 47 ]
Berkeley wrote about the perception of size in addition to that of distance. He is frequently misquoted as believing in size–distance invariance—a view held by the Optic Writers. This idea is that we scale the image size according to distance in a geometrical manner. The error may have become commonplace because the eminent historian and psychologist E. G. Boring perpetuated it. [ 48 ] In fact, Berkeley argued that the same cues that evoke distance also evoke size, and that we do not first see size and then calculate distance. [ 49 ] It is worth quoting Berkeley's words on this issue (Section 53):
What inclines men to this mistake (beside the humour of making one see by geometry) is, that the same perceptions or ideas which suggest distance, do also suggest magnitude ... I say they do not first suggest distance, and then leave it to the judgement to use that as a medium, whereby to collect the magnitude; but they have as close and immediate a connexion with the magnitude as with the distance; and suggest magnitude as independently of distance, as they do distance independently of magnitude.
Berkeley claimed that his visual theories were "vindicated" by a 1728 report regarding the recovery of vision in a 13-year-old boy operated for congenital cataracts by surgeon William Cheselden. In 2021, the name of Cheselden's patient was published for the first time: Daniel Dolins. [ 50 ] Berkeley knew the Dolins family, had numerous social links to Cheselden, including the poet Alexander Pope, and Princess Caroline, to whom Cheselden's patient was presented. [ 50 ] The report misspelt Cheselden's name, used language typical of Berkeley, and may even have been ghost-written by Berkeley. [ 50 ] Unfortunately, Dolins was never able to see well enough to read, and there is no evidence that the surgery improved Dolins' vision at any point prior to his death at age 30. [ 50 ]
"Berkeley's works display his keen interest in natural philosophy [...] from his earliest writings ( Arithmetica , 1707) to his latest ( Siris , 1744). Moreover, much of his philosophy is shaped fundamentally by his engagement with the science of his time." [ 51 ] The profundity of this interest can be judged from numerous entries in Berkeley's Philosophical Commentaries (1707–1708), e.g. "Mem. to Examine & accurately discuss the scholium of the 8th Definition of Mr Newton's Principia." (#316)
Berkeley argued that forces and gravity, as defined by Newton, constituted "occult qualities" that "expressed nothing distinctly". He held that those who posited "something unknown in a body of which they have no idea and which they call the principle of motion, are in fact simply stating that the principle of motion is unknown". Therefore, those who "affirm that active force, action, and the principle of motion are really in bodies are adopting an opinion not based on experience". [ 52 ] Forces and gravity existed nowhere in the phenomenal world. On the other hand, if they resided in the category of "soul" or "incorporeal thing", they "do not properly belong to physics" as a matter. Berkeley thus concluded that forces lay beyond any kind of empirical observation and could not be a part of proper science. [ 53 ] He proposed his theory of signs as a means to explain motion and matter without reference to the "occult qualities" of force and gravity.
Berkeley's razor is a rule of reasoning proposed by the philosopher Karl Popper in his study of Berkeley's key scientific work De Motu . [ 11 ] Berkeley's razor is considered by Popper to be similar to Ockham's razor but "more powerful". It represents an extreme, empiricist view of scientific observation that states that the scientific method provides us with no true insight into the nature of the world. Rather, the scientific method gives us a variety of partial explanations about regularities that hold in the world and that are gained through experiments. The nature of the world, according to Berkeley, is only approached through proper metaphysical speculation and reasoning. [ 54 ] Popper summarises Berkeley's razor as such:
A general practical result—which I propose to call "Berkeley's razor"—of [Berkeley's] analysis of physics allows us a priori to eliminate from physical science all essentialist explanations. If they have a mathematical and predictive content they may be admitted qua mathematical hypotheses (while their essentialist interpretation is eliminated). If not they may be ruled out altogether. This razor is sharper than Ockham's: all entities are ruled out except those which are perceived. [ 55 ]
In another essay of the same book [ 56 ] titled "Three Views Concerning Human Knowledge", Popper argues that Berkeley is to be considered as an instrumentalist philosopher, along with Robert Bellarmine , Pierre Duhem and Ernst Mach . According to this approach, scientific theories have the status of serviceable fictions, useful inventions aimed at explaining facts, and without any pretension to being true. Popper contrasts instrumentalism with the above-mentioned essentialism and his own " critical rationalism ".
In addition to his contributions to philosophy, Berkeley was also very influential in the development of mathematics , although in a rather indirect sense. "Berkeley was concerned with mathematics and its philosophical interpretation from the earliest stages of his intellectual life." [ 15 ] Berkeley's "Philosophical Commentaries" (1707–1708) witness to his interest in mathematics:
Axiom. No reasoning about things whereof we have no idea. Therefore no reasoning about Infinitesimals. (#354)
Take away the signs from Arithmetic & Algebra, & pray what remains? (#767)
These are sciences purely Verbal, & entirely useless but for Practise in Societys of Men. No speculative knowledge, no comparison of Ideas in them. (#768)
In 1707, Berkeley published two treatises on mathematics. In 1734, he published The Analyst , subtitled A DISCOURSE Addressed to an Infidel Mathematician , a critique of calculus . Florian Cajori called this treatise "the most spectacular event of the century in the history of British mathematics." [ 57 ] However, a recent study suggests that Berkeley misunderstood Leibnizian calculus. [ 58 ] The mathematician in question is believed to have been either Edmond Halley , or Isaac Newton himself—though if to the latter, then the discourse was posthumously addressed, as Newton died in 1727. The Analyst represented a direct attack on the foundations and principles of calculus and, in particular, the notion of fluxion or infinitesimal change, which Newton and Leibniz used to develop the calculus. In his critique, Berkeley coined the phrase " ghosts of departed quantities ", familiar to students of calculus. Ian Stewart 's book From Here to Infinity captures the gist of his criticism.
Berkeley regarded his criticism of calculus as part of his broader campaign against the religious implications of Newtonian mechanics – as a defence of traditional Christianity against deism , which tends to distance God from His worshipers. Specifically, he observed that both Newtonian and Leibnizian calculus employed infinitesimals sometimes as positive, nonzero quantities and other times as a number explicitly equal to zero. Berkeley's key point in "The Analyst" was that Newton's calculus (and the laws of motion based on calculus) lacked rigorous theoretical foundations. He claimed that:
In every other Science Men prove their Conclusions by their Principles, and not their Principles by the Conclusions. But if in yours you should allow your selves this unnatural way of proceeding, the Consequence would be that you must take up with Induction, and bid adieu to Demonstration. And if you submit to this, your Authority will no longer lead the way in Points of Reason and Science. [ 59 ]
Berkeley did not doubt that calculus produced real-world truth; simple physics experiments could verify that Newton's method did what it claimed to do. "The cause of Fluxions cannot be defended by reason", [ 60 ] but the results could be defended by empirical observation, Berkeley's preferred method of acquiring knowledge at any rate. Berkeley, however, found it paradoxical that "Mathematicians should deduce true Propositions from false Principles, be right in Conclusion, and yet err in the Premises." In The Analyst he endeavoured to show "how Error may bring forth Truth, though it cannot bring forth Science". [ 61 ] Newton's science, therefore, could not on purely scientific grounds justify its conclusions, and the mechanical, deistic model of the universe could not be rationally justified. [ 62 ]
The difficulties raised by Berkeley were still present in the work of Cauchy whose approach to calculus was a combination of infinitesimals and a notion of limit, and were eventually sidestepped by Weierstrass by means of his (ε, δ) approach, which eliminated infinitesimals altogether. More recently, Abraham Robinson restored infinitesimal methods in his 1966 book Non-standard analysis by showing that they can be used rigorously.
The tract A Discourse on Passive Obedience (1712) is considered Berkeley's major contribution to moral and political philosophy.
In A Discourse on Passive Obedience , Berkeley defends the thesis that people have "a moral duty to observe the negative precepts (prohibitions) of the law, including the duty not to resist the execution of punishment." [ 63 ] However, Berkeley does make exceptions to this sweeping moral statement, stating that we need not observe precepts of "usurpers or even madmen" [ 64 ] and that people can obey different supreme authorities if there are more than one claims to the highest authority.
Berkeley defends this thesis with deductive proof stemming from the laws of nature. First, he establishes that because God is perfectly good, the end to which he commands humans must also be good, and that end must not benefit just one person, but the entire human race. Because these commands—or laws—if practised, would lead to the general fitness of humankind, it follows that they can be discovered by the right reason—for example, the law to never resist supreme power can be derived from reason because this law is "the only thing that stands between us and total disorder". [ 63 ] Thus, these laws can be called the laws of nature , because they are derived from God—the creator of nature himself. "These laws of nature include duties never to resist the supreme power, lie under oath ... or do evil so that good may come of it." [ 63 ]
One may view Berkeley's doctrine on Passive Obedience as a kind of 'Theological Utilitarianism', insofar as it states that we have a duty to uphold a moral code which presumably is working towards the ends of promoting the good of humankind. However, the concept of 'ordinary' utilitarianism is fundamentally different in that it "makes utility the one and only ground of obligation" [ 65 ] —that is, Utilitarianism is concerned with whether particular actions are morally permissible in specific situations, while Berkeley's doctrine is concerned with whether or not we should follow moral rules in any and all circumstances. Whereas act utilitarianism might, for example, justify a morally impermissible act in light of the specific situation, Berkeley's doctrine of Passive Obedience holds that it is never morally permissible to not follow a moral rule, even when it seems like breaking that moral rule might achieve the happiest ends. Berkeley holds that even though sometimes, the consequences of an action in a specific situation might be bad, the general tendencies of that action benefit humanity.
Other important sources for Berkeley's views on morality are Alciphron (1732), especially dialogues I–III, and the Discourse to Magistrates (1738)." [ 66 ] Passive Obedience is notable partly for containing one of the earliest statements of rule utilitarianism . [ 67 ]
George Berkeley’s theory that matter does not exist comes from the belief that "sensible things are those only which are immediately perceived by sense." [ 68 ] Berkeley says in his book called Principles of Human Knowledge that "the ideas of sense are stronger, livelier, and clearer than those of the imagination; and they are also steady, orderly and coherent." [ 69 ] From this we can tell that the things that we are perceiving are truly real rather than it just being a dream.
All knowledge comes from perception; what we perceive are ideas, not things in themselves; a thing in itself must be outside experience; so the world only consists of ideas and minds that perceive those ideas; a thing only exists so far as it perceives or is perceived. [ 70 ] Through this we can see that consciousness is considered something that exists to Berkeley due to its ability to perceive. "'To be,' said of the object, means to be perceived, 'esse est percipi'; 'to be', said of the subject, means to perceive or 'percipere'." [ 71 ] Having established this, Berkeley then attacks the "opinion strangely prevailing amongst men, that houses, mountains, rivers, and in a word all sensible objects have an existence natural or real, distinct from being perceived". [ 69 ] He believes this idea to be inconsistent because such an object with an existence independent of perception must have both sensible qualities, and thus be known (making it an idea), and also an insensible reality, which Berkeley believes is inconsistent. [ 72 ] Berkeley believes that the error arises because people think that perceptions can imply or infer something about the material object. Berkeley calls this concept abstract ideas . He rebuts this concept by arguing that people cannot conceive of an object without also imagining the sensual input of the object. He argues in Principles of Human Knowledge that, similar to how people can only sense matter with their senses through the actual sensation, they can only conceive of matter (or, rather, ideas of matter) through the idea of sensation of matter. [ 69 ] This implies that everything that people can conceive in regards to matter is only ideas about matter. Thus, matter, should it exist, must exist as collections of ideas, which can be perceived by the senses and interpreted by the mind. But if matter is just a collection of ideas, then Berkeley concludes that matter, in the sense of a material substance, does not exist as most philosophers of Berkeley's time believed. Indeed, if a person visualizes something, then it must have some colour, however dark or light; it cannot just be a shape of no colour at all if a person is to visualize it. [ 73 ]
Berkeley's ideas raised controversy because his argument refuted Descartes ' philosophy, which was expanded upon by Locke, and resulted in the rejection of Berkeley's form of empiricism by several philosophers of the eighteenth century. In Locke's philosophy, "the world causes the perceptual ideas we have of it by the way it interacts with our senses." [ 70 ] This contradicts with Berkeley's philosophy because not only does it suggest the existence of physical causes in the world, but in fact, there is no physical world beyond our ideas. The only causes that exist in Berkeley's philosophy are those that are a result of the use of the will.
Berkeley's theory relies heavily on his form of empiricism , which in turn relies heavily on the senses. His empiricism can be defined by five propositions: all significant words stand for ideas; all knowledge of things is about ideas; all ideas come from without or from within; if from without it must be by the senses, and they are called sensations (the real things), if from within they are the operations of the mind, and are called thoughts. [ 73 ] Berkeley clarifies his distinction between ideas by saying they "are imprinted on the senses," "perceived by attending to the passions and operations of the mind," or "are formed by help of memory and imagination." [ 73 ] One refutation of his idea was: if someone leaves a room and stops perceiving that room does that room no longer exist? Berkeley answers this by claiming that it is still being perceived and the consciousness that is doing the perceiving is God . (This makes Berkeley's argument hinge upon an omniscient , omnipresent deity.) This claim is the only thing holding up his argument which is "depending for our knowledge of the world, and of the existence of other minds, upon a God that would never deceive us." [ 70 ] Berkeley anticipates a second objection, which he refutes in Principles of Human Knowledge . He anticipates that the materialist may take a representational materialist standpoint: although the senses can only perceive ideas, these ideas resemble (and thus can be compared to) the actual, existing object. Thus, through the sensing of these ideas, the mind can make inferences as to matter itself, even though pure matter is non-perceivable. Berkeley's objection to that notion is that "an idea can be like nothing but an idea; a colour or figure can be like nothing but another colour or figure". [ 69 ] Berkeley distinguishes between an idea, which is mind-dependent, and a material substance, which is not an idea and is mind-independent. As they are not alike, they cannot be compared, just as one cannot compare the colour red to something that is invisible, or the sound of music to silence, other than that one exists and the other does not. This is called the likeness principle: the notion that an idea can only be like (and thus compared to) another idea.
Berkeley attempted to show how ideas manifest themselves into different objects of knowledge:
It is evident to anyone who takes a survey of the objects of human knowledge, that they are either ideas actually imprinted on the senses; or else such as are perceived by attending to the passions and operations of the mind; or lastly ideas formed by help of memory and imagination—either compounding, dividing, or barely representing those originally perceived in the aforesaid ways". (Berkeley's emphasis.) [ 74 ]
Berkeley also attempted to prove the existence of God throughout his beliefs in immaterialism. [ 4 ]
Berkeley's Treatise Concerning the Principles of Human Knowledge was published three years before the publication of Arthur Collier 's Clavis Universalis , which made assertions similar to those of Berkeley's. [ 75 ] However, there seemed to have been no influence or communication between the two writers. [ 76 ]
German philosopher Arthur Schopenhauer once wrote of him: "Berkeley was, therefore, the first to treat the subjective starting-point really seriously and to demonstrate irrefutably its absolute necessity. He is the father of idealism ...". [ 77 ]
Berkeley is considered one of the originators of British empiricism . [ 78 ] A linear development is often traced from three great "British Empiricists", leading from Locke through Berkeley to Hume. [ 79 ]
Berkeley influenced many modern philosophers , especially David Hume . Thomas Reid admitted that he put forward a drastic criticism of Berkeleianism after he had been an admirer of Berkeley's philosophical system for a long time. [ 80 ] Berkeley's "thought made possible the work of Hume and thus Kant , notes Alfred North Whitehead ". [ 81 ] Some authors [ who? ] draw a parallel between Berkeley and Edmund Husserl . [ clarification needed ] [ 82 ]
When Berkeley visited America, the American educator Samuel Johnson visited him, and the two later corresponded. Johnson convinced Berkeley to establish a scholarship program at Yale and to donate a large number of books, as well as his plantation, to the college when the philosopher returned to England. It was one of Yale's largest and most important donations; it doubled its library holdings, improved the college's financial position and brought Anglican religious ideas and English culture into New England. [ 83 ] Johnson also took Berkeley's philosophy and used parts of it as a framework for his own American Practical Idealism school of philosophy. As Johnson's philosophy was taught to about half the graduates of American colleges between 1743 and 1776, [ 84 ] and over half of the contributors to the Declaration of Independence were connected to it, [ 85 ] Berkeley's ideas were indirectly a foundation of the American Mind.
Outside of America, during Berkeley's lifetime, his philosophical ideas were comparatively uninfluential. [ 86 ] But interest in his doctrine grew from the 1870s when Alexander Campbell Fraser , "the leading Berkeley scholar of the nineteenth century", [ 87 ] published The Works of George Berkeley . A powerful impulse to serious studies in Berkeley's philosophy was given by A. A. Luce and Thomas Edmund Jessop , "two of the twentieth century's foremost Berkeley scholars", [ 88 ] thanks to whom Berkeley scholarship was raised to the rank of a special area of historico-philosophical science. In addition, the philosopher Colin Murray Turbayne wrote extensively on Berkeley's use of language as a model for visual, physiological, natural and metaphysical relationships. [ 89 ] [ 90 ] [ 91 ] [ 92 ]
The proportion of Berkeley scholarship, in literature on the history of philosophy, is increasing. This can be judged from the most comprehensive bibliographies on George Berkeley. During the period of 1709–1932, about 300 writings on Berkeley were published. That amounted to 1.5 publications per year. During the course of 1932–1979, over one thousand works were brought out, i.e., 20 works per year. Since then, the number of publications has reached 30 per annum. [ 93 ] In 1977 publication began in Ireland of a special journal on Berkeley's life and thought ( Berkeley Studies ). In 1988, the Australian philosopher Colin Murray Turbayne established the International Berkeley Essay Prize Competition at the University of Rochester in an effort to advance scholarship and research on the works of Berkeley. [ 94 ] [ 95 ]
Other than philosophy, Berkeley also influenced modern psychology with his work on John Locke's theory of association and how it could be used to explain how humans gain knowledge in the physical world. He also used the theory to explain perception, stating that all qualities were, as Locke would call them, "secondary qualities", therefore perception laid entirely in the perceiver and not in the object. These are both topics today studied in modern psychology. [ 96 ]
Lord Byron 's Don Juan references immaterialism in the Eleventh Canto:
When Bishop Berkeley said 'there was no matter,' And proved it—'t was no matter what he said: They say his system 't is in vain to batter, Too subtle for the airiest human head; And yet who can believe it? I would shatter Gladly all matters down to stone or lead, Or adamant, to find the world a spirit, And wear my head, denying that I wear it.
Herman Melville humorously references Berkeley in Chapter 20 of Mardi (1849), when outlining a character's belief of being on board a ghostship:
And here be it said, that for all his superstitious misgivings about the brigantine; his imputing to her something equivalent to a purely phantom-like nature, honest Jarl was nevertheless exceedingly downright and practical in all hints and proceedings concerning her. Wherein, he resembled my Right Reverend friend, Bishop Berkeley–truly, one of your lords spiritual—who, metaphysically speaking, holding all objects to be mere optical delusions, was, notwithstanding, extremely matter-of-fact in all matters touching matter itself. Besides being pervious to the points of pins, and possessing a palate capable of appreciating plum-puddings:—which sentence reads off like a pattering of hailstones.
James Joyce references Berkeley's philosophy in the third episode of Ulysses (1922):
Who watches me here? Who ever anywhere will read these written words? Signs on a white field. Somewhere to someone in your flutiest voice. The good bishop of Cloyne took the veil of the temple out of his shovel hat: veil of space with coloured emblems hatched on its field. Hold hard. Coloured on a flat: yes, that's right. Flat I see, then think distance, near, far, flat I see, east, back. Ah, see now!
In commenting on a review of Ada or Ardor , author Vladimir Nabokov alludes to Berkeley's philosophy as informing his novel:
And finally I owe no debt whatsoever (as Mr. Leonard seems to think) to the famous Argentine essayist and his rather confused compilation "A New Refutation of Time." Mr. Leonard would have lost less of it had he gone straight to Berkeley and Bergson. ( Strong Opinions , pp. 2892–90)
James Boswell , in the part of his Life of Samuel Johnson covering the year 1763, recorded Johnson's opinion of one aspect of Berkeley's philosophy:
After we came out of the church, we stood talking for some time together of Bishop Berkeley's ingenious sophistry to prove the non-existence of matter, and that every thing in the universe is merely ideal. I observed, that though we are satisfied his doctrine is untrue, it is impossible to refute it. I shall never forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it,– "I refute it thus ."
Both the University of California, Berkeley , and the city of Berkeley, California , were named after him, although the pronunciation has evolved to suit American English : ( / ˈ b ɜːr k l i / BURK -lee ). The naming was suggested in 1866 by Frederick H. Billings , a trustee of what was then called the College of California . Billings was inspired by Berkeley's Verses on the Prospect of Planting Arts and Learning in America , particularly the final stanza: "Westward the course of empire takes its way; the first four Acts already past, a fifth shall close the Drama with the day; time's noblest offspring is the last". [ 97 ]
The Town of Berkley , currently the least populated town in Bristol County, Massachusetts , was founded on 18 April 1735 and named for George Berkeley.
A residential college and an Episcopal seminary at Yale University also bear Berkeley's name.
"Bishop Berkeley's Gold Medals" were two awards given annually at Trinity College Dublin , "provided outstanding merit is shown", to candidates answering a special examination in Greek. The awards were founded in 1752 by Berkeley. [ 98 ] However, they have not been awarded since 2011. [ 99 ] Other elements of Berkeley's legacy at Trinity are currently under review (As of 2023 [update] ) due to his support of slavery . For example, the library at Trinity that was named after him in 1978 was "de-named" in April 2023 and renamed in October 2024 after Irish poet Eavan Boland. Another memorialization of him in the form of a stained glass window will remain, but used as part of "a retain-and-explain approach" where his legacy will be given further context. [ 99 ] [ 100 ]
An Ulster History Circle blue plaque commemorating him is located in Bishop Street Within, the city of Derry.
Berkeley's farmhouse in Middletown, Rhode Island, is preserved as Whitehall Museum House , also known as Berkeley House, and was listed on the National Register of Historic Places in 1970. St. Columba's Chapel , located in the same town, was formerly named "The Berkeley Memorial Chapel", and the appellation still survives at the end of the formal name of the parish, "St. Columba's, the Berkeley Memorial Chapel". | https://en.wikipedia.org/wiki/George_Berkeley |
George Blasse (28 August 1934 – 30 December 2020) was a Dutch chemist. He was a professor of solid-state chemistry at Utrecht University for most of his career.
Blasse was born on 28 August 1934 in Amsterdam . [ 1 ] He studied chemistry at the University of Amsterdam . In 1964 he obtained his PhD under E.W. Gorter at Leiden University with a dissertation titled: Chrystal chemistry and some magnetic properties of mixed metal oxides with spinel structure. From 1960 to 1970 Blasse was employed by the Philips Natuurkundig Laboratorium . [ 2 ] In 1970 he was appointed as professor of solid-state chemistry at Utrecht University. He retired in 1996. [ 1 ]
During his career he performed research into luminescent materials. He discovered the phosphor that made white light LEDs possible. [ 3 ]
Blasse was elected a member of the Royal Netherlands Academy of Arts and Sciences in 1982. [ 4 ] In 1992 he was awarded the Academy's Gilles Holst Medal. [ 5 ] Blasse was elected a member of the Academia Europaea in 1993. [ 6 ] In 1996 he was made a Knight in the Order of the Netherlands Lion . [ 7 ]
After his retirement he moved to Munich , Germany. [ 3 ] He died there on 30 December 2020, aged 86. [ 8 ] After his death the ECS Journal of Solid State Science and Technology had a focus issue in his honor. [ 3 ] | https://en.wikipedia.org/wiki/George_Blasse |
George Boole ( / b uː l / BOOL ; 2 November 1815 – 8 December 1864) was a largely self-taught English mathematician , philosopher and logician , most of whose short career was spent as the first professor of mathematics at Queen's College, Cork in Ireland. He worked in the fields of differential equations and algebraic logic , and is best known as the author of The Laws of Thought (1854), which contains Boolean algebra . Boolean logic, essential to computer programming , is credited with helping to lay the foundations for the Information Age . [ 4 ] [ 5 ] [ 6 ]
Boole was the son of a shoemaker. He received a primary school education and learned Latin and modern languages through various means. At 16, he began teaching to support his family. He established his own school at 19 and later ran a boarding school in Lincoln. Boole was an active member of local societies and collaborated with fellow mathematicians. In 1849, he was appointed the first professor of mathematics at Queen's College, Cork (now University College Cork) in Ireland, where he met his future wife, Mary Everest . He continued his involvement in social causes and maintained connections with Lincoln. In 1864, Boole died due to fever-induced pleural effusion after developing pneumonia .
Boole published around 50 articles and several separate publications in his lifetime. Some of his key works include a paper on early invariant theory and "The Mathematical Analysis of Logic", which introduced symbolic logic. Boole also wrote two systematic treatises: "Treatise on Differential Equations" and "Treatise on the Calculus of Finite Differences". He contributed to the theory of linear differential equations and the study of the sum of residues of a rational function. In 1847, Boole developed Boolean algebra, a fundamental concept in binary logic, which laid the groundwork for the algebra of logic tradition and forms the foundation of digital circuit design and modern computer science. Boole also attempted to discover a general method in probabilities, focusing on determining the consequent probability of events logically connected to given probabilities.
Boole's work was expanded upon by various scholars, such as Charles Sanders Peirce and William Stanley Jevons. Boole's ideas later gained practical applications when Claude Shannon and Victor Shestakov employed Boolean algebra to optimize the design of electromechanical relay systems, leading to the development of modern electronic digital computers. His contributions to mathematics earned him various honours, including the Royal Society's first gold prize for mathematics, the Keith Medal, and honorary degrees from the Universities of Dublin and Oxford. University College Cork celebrated the 200th anniversary of Boole's birth in 2015, highlighting his significant impact on the digital age.
Boole was born in 1815 in Lincoln , Lincolnshire , England, the son of John Boole Snr (1779–1848), a shoemaker [ 7 ] and Mary Ann Joyce. [ 8 ] He had a primary school education, and received lessons from his father, but due to a serious decline in business, he had little further formal and academic teaching. [ 9 ] William Brooke, a bookseller in Lincoln, may have helped him with Latin, which he may also have learned at the school of Thomas Bainbridge. He was self-taught in modern languages. [ 2 ] In fact, when a local newspaper printed his translation of a Latin poem, a scholar accused him of plagiarism under the pretence that he was not capable of such achievements. [ 10 ] At age 16, Boole became the breadwinner for his parents and three younger siblings, taking up a junior teaching position in Doncaster at Heigham's School. [ 11 ] He taught briefly in Liverpool . [ 1 ]
Boole participated in the Lincoln Mechanics' Institute , in the Greyfriars, Lincoln , which was founded in 1833. [ 2 ] [ 12 ] Edward Bromhead , who knew John Boole through the institution, helped George Boole with mathematics books [ 13 ] and he was given the calculus text of Sylvestre François Lacroix by the Rev. George Stevens Dickson of St Swithin's, Lincoln . [ 14 ] Without a teacher, it took him many years to master calculus. [ 1 ]
At age 19, Boole successfully established his own school in Lincoln: Free School Lane. [ 15 ] Four years later he took over Hall's Academy in Waddington , outside Lincoln, following the death of Robert Hall. In 1840, he moved back to Lincoln, where he ran a boarding school. [ 1 ] Boole immediately became involved in the Lincoln Topographical Society, serving as a member of the committee, and presenting a paper entitled "On the origin, progress, and tendencies of polytheism, especially amongst the ancient Egyptians and Persians, and in modern India". [ 16 ]
Boole became a prominent local figure, an admirer of John Kaye , the bishop. [ 17 ] He took part in the local campaign for early closing . [ 2 ] With Edmund Larken and others he set up a building society in 1847. [ 18 ] He associated also with the Chartist Thomas Cooper , whose wife was a relation. [ 19 ]
From 1838 onwards, Boole was making contacts with sympathetic British academic mathematicians and reading more widely. He studied algebra in the form of symbolic methods, as far as these were understood at the time, and began to publish research papers. [ 1 ]
Boole's status as a mathematician was recognised by his appointment in 1849 as the first professor of mathematics at Queen's College, Cork (now University College Cork (UCC)) in Ireland. He met his future wife, Mary Everest , there in 1850 while she was visiting her uncle John Ryall who was professor of Greek. They married in 1855. [ 20 ] [ 21 ] He maintained his ties with Lincoln, working there with E. R. Larken in a campaign to reduce prostitution. [ 22 ]
In 1861, Boole was involved in a Judgement in the Court of Queen's Bench in Ireland against one John Hewitt Wheatley of Craig House, Sligo for the sum of £400, whereby Wheatley's estate and interest in lands of Maghan/Mahon, County Cork became vested in Boole. [ 23 ]
In March 1863, Boole leased Litchfield Cottage, Cork, the house in which he would live with his wife Mary until his death in December of the following year. [ 24 ] The premises was described in the deeds as "all that and those the dwelling house called Litchfield Cottage with the premises and appurtenances thereunto belonging and the Garden and Walled in field to the rere thereof". Boole's will bequeathed all his 'estate term and interest' in the lease of Litchfield Cottage unto his wife. [ 25 ] In August 1865, some 8 months after his death, Mary (by then living at 68 Harley Street, London) passed the house on to Francis Heard of Ballintemple, Cork, Esquire, a captain in her Majesty's 87th Regiment of South Cork.
In 1844, Boole's paper "On a General Method in Analysis" won the first gold prize for mathematics awarded by the Royal Society . [ 27 ] He was awarded the Keith Medal by the Royal Society of Edinburgh in 1855 [ 28 ] and was elected a Fellow of the Royal Society (FRS) in 1857 . [ 14 ] He received honorary degrees of LL.D. from the University of Dublin and the University of Oxford . [ 29 ]
Boole's first published paper was "Researches in the theory of analytical transformations, with a special application to the reduction of the general equation of the second order", printed in the Cambridge Mathematical Journal in February 1840 (Volume 2, No. 8, pp. 64–73), and it led to his friendship with Duncan Farquharson Gregory , the editor of the journal. [ 20 ] His works are in about 50 articles and a few separate publications. [ 30 ] [ 22 ]
In 1841, Boole published an influential paper in early invariant theory . [ 14 ] He received a medal from the Royal Society for his memoir of 1844, "On a General Method in Analysis". [ 20 ] It was a contribution to the theory of linear differential equations , moving from the case of constant coefficients on which he had already published, to variable coefficients. [ 31 ] The innovation in operational methods is to admit that operations may not commute . [ 32 ] In 1847, Boole published The Mathematical Analysis of Logic , the first of his works on symbolic logic. [ 33 ]
Boole completed two systematic treatises on mathematical subjects during his lifetime. The Treatise on Differential Equations [ 34 ] appeared in 1859, and was followed, the next year, by a Treatise on the Calculus of Finite Differences , [ 35 ] a sequel to the former work. [ 20 ] Shortly after his death, Todhunter republished Boole's treatise with some of Boole's revisions, along with a supplement that was originally intended to be merged in the making of the second edition.
In 1857, Boole published the treatise "On the Comparison of Transcendent, with Certain Applications to the Theory of Definite Integrals", [ 36 ] in which he studied the sum of residues of a rational function . Among other results, he proved what is now called Boole's identity:
for any real numbers a k > 0, b k , and t > 0. [ 37 ] Generalisations of this identity play an important role in the theory of the Hilbert transform . [ 37 ]
In 1847, Boole published the pamphlet Mathematical Analysis of Logic . He later regarded it as a flawed exposition of his logical system and wanted An Investigation of the Laws of Thought on Which are Founded the Mathematical Theories of Logic and Probabilities to be seen as the mature statement of his views. [ 20 ] Contrary to widespread belief, Boole never intended to criticise or disagree with the main principles of Aristotle 's logic. Rather he intended to systematise it, to provide it with a foundation, and to extend its range of applicability. [ 38 ] Boole's initial involvement in logic was prompted by a current debate on quantification , between Sir William Hamilton who supported the theory of "quantification of the predicate", and Boole's supporter Augustus De Morgan who advanced a version of De Morgan duality , as it is now called. Boole's approach was ultimately much further reaching than either sides' in the controversy. [ 39 ] It founded what was first known as the "algebra of logic" tradition. [ 40 ]
Among his many innovations is his principle of wholistic reference , which was later, and probably independently, adopted by Gottlob Frege and by logicians who subscribe to standard first-order logic. A 2003 article [ 41 ] provides a systematic comparison and critical evaluation of Aristotelian logic and Boolean logic ; it also reveals the centrality of holistic reference in Boole's philosophy of logic .
In every discourse, whether of the mind conversing with its own thoughts, or of the individual in his intercourse with others, there is an assumed or expressed limit within which the subjects of its operation are confined. The most unfettered discourse is that in which the words we use are understood in the widest possible application, and for them, the limits of discourse are co-extensive with those of the universe itself. But more usually we confine ourselves to a less spacious field. Sometimes, in discoursing of men we imply (without expressing the limitation) that it is of men only under certain circumstances and conditions that we speak, as of civilised men, or of men in the vigour of life, or of men under some other condition or relation. Now, whatever may be the extent of the field within which all the objects of our discourse are found, that field may properly be termed the universe of discourse . Furthermore, this universe of discourse is in the strictest sense the ultimate subject of the discourse. [ 42 ]
Boole conceived of "elective symbols" of his kind as an algebraic structure . But this general concept was not available to him: he did not have the segregation standard in abstract algebra of postulated (axiomatic) properties of operations, and deduced properties. [ 43 ] His work was a beginning to the algebra of sets , again not a concept available to Boole as a familiar model. His pioneering efforts encountered specific difficulties, and the treatment of addition was an obvious difficulty in the early days.
Boole replaced the operation of multiplication by the word "and" and addition by the word "or". But in Boole's original system, + was a partial operation : in the language of set theory it would correspond only to the union of disjoint subsets. Later authors changed the interpretation, commonly reading it as exclusive or , or in set theory terms symmetric difference ; this step means that addition is always defined. [ 40 ] [ 44 ]
In fact, there is the other possibility generalizing Boole's original partial operation, that + should be read as non-exclusive or . [ 43 ] Handling this ambiguity was an early problem of the theory, reflecting the modern use of both Boolean rings and Boolean algebras (which are simply different aspects of one type of structure). Boole and Jevons struggled over just this issue in 1863, in the form of the correct evaluation of x + x . Jevons argued for the result x , which is correct for + as disjunction. Boole kept the result as something undefined. He argued against the result 0, which is correct for exclusive or, because he saw the equation x + x = 0 as implying x = 0, a false analogy with ordinary algebra. [ 14 ]
The second part of the Laws of Thought contained a corresponding attempt to discover a general method in probabilities . Here the goal was algorithmic: from the given probabilities of any system of events, to determine the consequent probability of any other event logically connected with those events. [ 45 ] [ 20 ]
In late November 1864, Boole walked, in heavy rain, from his home at Lichfield Cottage in Ballintemple [ 46 ] to the university, a distance of three miles, and lectured wearing his wet clothes. [ 47 ] He soon became ill, developing pneumonia. As his wife believed that remedies should resemble their cause, she wrapped him in wet blankets – the wet having brought on his illness. [ 47 ] [ 48 ] [ 49 ] Boole's condition worsened and on 8 December 1864, [ 50 ] he died of fever-induced pleural effusion .
He was buried in the Church of Ireland cemetery of St Michael's, Church Road, Blackrock (a suburb of Cork ). There is a commemorative plaque inside the adjoining church. [ 51 ]
Boole is the namesake of the branch of algebra known as Boolean algebra , as well as the namesake of the lunar crater Boole . The keyword Bool represents a Boolean data type in many programming languages, though Pascal and Java , among others, both use the full name Boolean . [ 52 ] The library, underground lecture theatre complex and the Boole Centre for Research in Informatics [ 53 ] at University College Cork are named in his honour. A road called Boole Heights in Bracknell, Berkshire is named after him.
Boole's work was extended and refined by a number of writers, beginning with William Stanley Jevons , who also authored the article about Boole in the Encyclopædia Britannica . Augustus De Morgan had worked on the logic of relations , and Charles Sanders Peirce integrated his work with Boole's during the 1870s. [ 54 ] Other significant figures were Platon Sergeevich Poretskii , and William Ernest Johnson . The conception of a Boolean algebra structure on equivalent statements of a propositional calculus is credited to Hugh MacColl (1877), in work surveyed 15 years later by Johnson. [ 54 ] Surveys of these developments were published by Ernst Schröder , Louis Couturat , and Clarence Irving Lewis .
In 1921, the economist John Maynard Keynes published a book on probability theory, A Treatise of Probability . Keynes believed that Boole had made a fundamental error in his definition of independence which vitiated much of his analysis. [ 55 ] In his book The Last Challenge Problem , David Miller provides a general method in accord with Boole's system and attempts to solve the problems recognised earlier by Keynes and others. Theodore Hailperin showed much earlier that Boole had used the correct mathematical definition of independence in his worked out problems. [ 56 ]
Boole's work and that of later logicians initially appeared to have no engineering uses. Claude Shannon attended a philosophy class at the University of Michigan which introduced him to Boole's studies. Shannon recognised that Boole's work could form the basis of mechanisms and processes in the real world and that it was therefore highly relevant. In 1937 Shannon went on to write a master's thesis, at the Massachusetts Institute of Technology , in which he showed how Boolean algebra could optimise the design of systems of electromechanical relays then used in telephone routing switches. He also proved that circuits with relays could solve Boolean algebra problems. Employing the properties of electrical switches to process logic is the basic concept that underlies all modern electronic digital computers . Victor Shestakov at Moscow State University (1907–1987) proposed a theory of electric switches based on Boolean logic even earlier than Claude Shannon in 1935 on the testimony of Soviet logicians and mathematicians Sofya Yanovskaya , Gaaze-Rapoport, Roland Dobrushin , Lupanov, Medvedev and Uspensky. But the first publication of Shestakov's result took place only in 1941 (in Russian). Hence, Boolean algebra became the foundation of practical digital circuit design; and Boole, via Shannon and Shestakov, provided the theoretical grounding for the Information Age . [ 57 ]
"Boole's legacy surrounds us everywhere, in the computers, information storage and retrieval, electronic circuits and controls that support life, learning and communications in the 21st century. His pivotal advances in mathematics, logic and probability provided the essential groundwork for modern mathematics, microelectronic engineering and computer science."
The year 2015 saw the 200th anniversary of Boole's birth. To mark the bicentenary year, University College Cork joined admirers of Boole around the world to celebrate his life and legacy.
UCC's George Boole 200 [ 58 ] project, featured events, student outreach activities and academic conferences on Boole's legacy in the digital age, including a new edition of Desmond MacHale 's 1985 biography The Life and Work of George Boole: A Prelude to the Digital Age , [ 59 ] 2014.
The search engine Google marked the 200th anniversary of his birth on 2 November 2015 with an algebraic reimaging of its Google Doodle . [ 4 ]
In September 2022, a statue of George Boole in his role as a teacher was unveiled at Lincoln Central Train Station , in Boole's home town of Lincoln .
Boole's views were given in four published addresses: The Genius of Sir Isaac Newton ; The Right Use of Leisure ; The Claims of Science ; and The Social Aspect of Intellectual Culture . [ 20 ] The first of these was from 1835 when Charles Anderson-Pelham, 1st Earl of Yarborough gave a bust of Newton to the Mechanics' Institute in Lincoln. [ 60 ] The second justified and celebrated in 1847 the outcome of the successful campaign for early closing in Lincoln, headed by Alexander Leslie-Melville, of Branston Hall . [ 61 ] The Claims of Science was given in 1851 at Queen's College, Cork. [ 62 ] The Social Aspect of Intellectual Culture was also given in Cork, in 1855 to the Cuvierian Society. [ 63 ]
Though his biographer Des MacHale describes Boole as an "agnostic deist", [ 64 ] [ 65 ] Boole read a wide variety of Christian theology. Combining his interests in mathematics and theology, he compared the Christian trinity of Father, Son, and Holy Ghost with the three dimensions of space, and was attracted to the Hebrew conception of God as an absolute unity. Boole considered converting to Judaism but in the end was said to have chosen Unitarianism . [reference?] Boole came to speak against what he saw as "prideful" scepticism, and instead favoured the belief in a "Supreme Intelligent Cause". [ 66 ] He also declared "I firmly believe, for the accomplishment of a purpose of the Divine Mind." [ 67 ] [ 68 ] In addition, he stated "To infer the existence of an intelligent cause from the teeming evidence of surrounding design , to rise to the conception of a moral Governor of the World, from the study of the constitution and the moral provisions of our own nature;--these, though but the feeble steps of an understanding limited in its faculties and its materials of knowledge, are of more avail than the ambitious attempt to arrive at a certainty unattainable on the ground of natural religion. And as these were the most ancient, so are they still the most solid foundations, Revelation being set apart, of the belief that the course of this world is not abandoned to chance and inexorable fate." [ 69 ] [ 70 ]
Two influences on Boole were later claimed by his wife, Mary Everest Boole : a universal mysticism tempered by Jewish thought, and Indian logic . [ 71 ] Mary Boole stated that an adolescent mystical experience provided for his life's work:
My husband told me that when he was a lad of seventeen a thought struck him suddenly, which became the foundation of all his future discoveries. It was a flash of psychological insight into the conditions under which a mind most readily accumulates knowledge ... For a few years he supposed himself to be convinced of the truth of "the Bible" as a whole, and even intended to take orders as a clergyman of the English Church. But by the help of a learned Jew in Lincoln he found out the true nature of the discovery which had dawned on him. This was that man's mind works by means of some mechanism which "functions normally towards Monism ." [ 72 ]
In Ch. 13 of Laws of Thought Boole used examples of propositions from Baruch Spinoza and Samuel Clarke . The work contains some remarks on the relationship of logic to religion, but they are slight and cryptic. [ 73 ] Boole was apparently disconcerted at the book's reception just as a mathematical toolset:
George afterwards learned, to his great joy, that the same conception of the basis of Logic was held by Leibniz , the contemporary of Newton. De Morgan, of course, understood the formula in its true sense; he was Boole's collaborator all along. Herbert Spencer, Jowett, and Robert Leslie Ellis understood, I feel sure; and a few others, but nearly all the logicians and mathematicians ignored [953] the statement that the book was meant to throw light on the nature of the human mind; and treated the formula entirely as a wonderful new method of reducing to logical order masses of evidence about external fact. [ 72 ]
Mary Boole claimed that there was profound influence – via her uncle George Everest – of Indian thought in general and Indian logic , in particular, on George Boole, as well as on Augustus De Morgan and Charles Babbage : [ 74 ]
Think what must have been the effect of the intense Hinduizing of three such men as Babbage, De Morgan, and George Boole on the mathematical atmosphere of 1830–65. What share had it in generating the Vector Analysis and the mathematics by which investigations in physical science are now conducted? [ 72 ]
Boole maintained that:
No general method for the solution of questions in the theory of probabilities can be established which does not explicitly recognise, not only the special numerical bases of the science, but also those universal laws of thought which are the basis of all reasoning, and which, whatever they may be as to their essence, are at least mathematical as to their form. [ 75 ]
In 1855, Boole married Mary Everest (niece of George Everest ), who later wrote several educational works on her husband's principles.
The Booles had five daughters: | https://en.wikipedia.org/wiki/George_Boole |
George Hermann Büchi (August 1, 1921 – August 28, 1998) was a Swiss organic chemist and professor at the Massachusetts Institute of Technology . "Paternò's reaction", known since the early twentieth century, [ 1 ] was renamed to the " Paternò–Büchi reaction " based on enhancements made to it by Büchi's research group. [ 2 ]
Büchi died at the age of 77 of heart failure while hiking with his wife in Switzerland. [ 3 ] [ 4 ]
This biographical article about a chemist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/George_Büchi |
The George Darwin Lectureship is an award granted by the Royal Astronomical Society to a 'distinguished and eloquent speaker' on the subject of Astronomy including astrochemistry , astrobiology and astroparticle physics . [ 1 ] The award is named after the astronomer George Darwin and has been given annually since 1984. [ 1 ] [ 2 ] The speaker may be based in the UK or overseas.
Laureates of the award include: [ 1 ] [ 3 ] | https://en.wikipedia.org/wiki/George_Darwin_Lectureship |
The George David Birkhoff Prize in applied mathematics is awarded jointly by the American Mathematical Society (AMS) and the Society for Industrial and Applied Mathematics (SIAM) in honor of George David Birkhoff (1884–1944). It is currently awarded every three years for an outstanding contribution to "applied mathematics in the highest and broadest sense." [ 1 ] [ 2 ] The recipient of the prize has to be a member of one of the awarding societies, as well as a resident of the United States of America , Canada , or Mexico . The prize was endowed in 1967, first issued in 1968, and currently (2020) amounts to US$ 5,000. | https://en.wikipedia.org/wiki/George_David_Birkhoff_Prize |
George Edward Davis (1850–1907) is regarded as the founding father of the discipline of chemical engineering . [ 1 ]
Davis was born at Eton on 27 July 1850, the eldest son of George Davis, a bookseller. At the age of fourteen he was apprenticed to a local bookbinder but he abandoned this trade after two years to pursue his interest in chemistry. Davis studied at the Slough Mechanics Institute while working at the local gas works , and then spent a year studying at the Royal School of Mines in London (now part of Imperial College, London ) before leaving to work in the chemical industry around Manchester , which at the time was the main centre of the chemical industry in the UK. [ 2 ] [ 3 ]
Davis worked as a chemist at Brearley and Sons for three years. He also worked as an inspector for the Alkali Act 1863 ( 26 & 27 Vict. c. 124), a very early piece of environmental legislation that required soda manufacturers to reduce the amount of gaseous hydrochloric acid released to the atmosphere from their factories. In 1872 he was engaged as manager at the Lichfield Chemical Company in Staffordshire . In this job his capacity for innovation flourished. His works included what was at the time the tallest chimney in the UK, with a height of more than 200 feet (61 m). [ 1 ]
He married Laura Frances Miller on 10 December 1878, and they had at least two sons, Eric (1881- ) and Kerville (1881 - 1934). [ 4 ] He worked as a consultant to the chemical industry jointly with his brother Alfred, founded the Chemical Trade Journal and had 67 patents granted, as well as publishing scientific papers. [ 1 ]
Davis was also instrumental in the formation of the Society of Chemical Industry (1881), which he had wanted to name the Society of Chemical Engineering , and was its first Secretary. [ 5 ] [ 6 ] [ 1 ] He was also interested in microscopy, founding the journal Northern Microscopist in 1881, and publishing a textbook on the subject, Practical Microscopy (1882). [ 1 ]
He died in West Dulwich , on 20 April 1907. [ 1 ]
Davis identified broad features in common to all chemical factories and wrote the influential A Handbook of Chemical Engineering . He also published a famous lecture series of 12 lectures, given in 1888 at Manchester Technical School (which became University of Manchester Institute of Science and Technology (UMIST)). These lectures defined chemical engineering as a discipline. [ 7 ] [ 1 ]
His lectures were criticized for being common place know-how since it was designed around operating practices used by British chemical industries. At this time, however, in the United States, this information helped initiate new thinking in the chemical industry, as well as spark chemical engineering degree programmes at several universities in the US. [ 1 ]
In the 1st floor foyer of Jackson's Mill, the building that houses the School of Chemical Engineering and Analytical Science, University of Manchester, there is a display and memorial to Davis. The George E. Davis Medal of the Institution of Chemical Engineers is named in his honour. | https://en.wikipedia.org/wiki/George_E._Davis |
The George E. Davis Medal is a medal of the IChemE given not more frequently than every three years, for achievements in chemical engineering . [ 1 ] It is named after George E. Davis .
Source: IChemE | https://en.wikipedia.org/wiki/George_E._Davis_Medal |
The George Ellery Hale Prize , or Hale Prize , is awarded annually by the Solar Physics Division of the American Astronomical Society for outstanding contributions over an extended period of time to the field of solar astronomy . The prize is named in memory of George Ellery Hale .
Past winners of the Hale Prize are: [ 1 ] | https://en.wikipedia.org/wiki/George_Ellery_Hale_Prize |
George François Cornelis Griss (30 January 1898, Amsterdam – 2 August 1953, Blaricum ), usually cited as G. F. C. Griss , was a Dutch mathematician and philosopher , who was occupied with Hegelian idealism and Brouwers intuitionism and stated a negationless mathematics.
Griss was a student of L. E. J. Brouwer and formulated an intuitionism based on a Hegelian idealism. He obtained his Ph.D. with Roland Weitzenböck at the University of Amsterdam in July 1925. He was largely influenced by L. E. J. Brouwer, Gerrit Mannoury , Carry van Bruggen and Gerard Bolland , who brought Hegelian thought to the Netherlands. He published a number of articles about a negationless mathematics and one small book about idealistic philosophy, called Idealistische Filosofie (17 February 1946, Gouda), in which he lays down a typically Hegelian idealism, and incorporates elements from Bergson 's Creative Evolution ( L'Evolution créatrice ). | https://en.wikipedia.org/wiki/George_F._C._Griss |
George Garfield Hall (5 March 1925 – 6 May 2018) was a Northern Irish applied mathematician known for original work and contributions to the field of quantum chemistry . [ 1 ] Independently from Clemens C. J. Roothaan , Hall discovered the Roothaan-Hall equations .
Hall was educated at Queen's University Belfast and St John's College, Cambridge , where he studied for a PhD under the supervision of John Lennard-Jones . For his work on the Roothaan-Hall equations, Hall was awarded a doctorate by the University of Cambridge in 1950. [ 2 ] He then lectured at Cambridge as a Research Assistant in theoretical chemistry , before being elected to a Fellowship at St John's College in 1953. From 1955 to 1962 he lectured in Mathematics at Imperial College London . In 1957–58 he spent a year with Per-Olov Löwdin in Uppsala , Sweden . He became Professor of Mathematics at the University of Nottingham in 1962. In 1982 he took early retirement from Nottingham and was appointed an emeritus professor. He moved in 1983 to Kyoto University , Japan , returning to Nottingham in 1988. He has collaborated with (inter alia) A.T. Amos, K. Collard, and D. Rees. He was Emeritus Professor and Senior Research Fellow in the Shell Centre for Mathematical Education at the University of Nottingham.
He was awarded several honorary degrees for his work: a DSc by Maynooth University (2004), a ScD by Cambridge University and a DEng by Kyoto University. He was a member of the International Academy of Quantum Molecular Science .
Hall had three children and six grandchildren. He died peacefully in Nottingham at the age of 93 on 6 May 2018.
This article about a British chemist is a stub . You can help Wikipedia by expanding it .
This article about a United Kingdom mathematician is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/George_G._Hall |
George Birch Jerrard (25 November 1804 – 23 November 1863) was a British mathematician .
He studied at Trinity College, Dublin from 1821 to 1827. His main work was on the theory of equations , where he was reluctant to accept the validity of the work of Niels Henrik Abel on the insolubility of the quintic equation by radicals . He found a way of using Tschirnhaus transformations to eliminate three of the terms in an equation, which generalised work of Erland Bring (1736–1798), and is now called Bring–Jerrard normal form .
This article about a United Kingdom mathematician is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/George_Jerrard |
George Mullen is an astronomer who co-authored several peer-reviewed articles with Carl Sagan . He, along with Sagan, pointed out the faint young Sun paradox . [ 1 ] [ 2 ] [ 3 ] [ 4 ] In addition to studying the early Earth atmosphere, he studied the atmosphere of Jupiter. [ 5 ] [ 6 ]
This article about an astronomer is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/George_Mullen |
George N. Phillips, Jr. is a biochemist , researcher, and academic. He is the Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology at Rice University , [ 1 ] where he also serves as Associate Dean for Research at the Wiess School of Natural Sciences and as a professor of chemistry. Additionally, he holds the title of professor emeritus of biochemistry at the University of Wisconsin-Madison . [ 2 ]
Phillips' research is primarily centered on protein structure , protein dynamics , and computational biology , with a specific emphasis on understanding the correlation between the dynamics of proteins and their biological functions . [ 3 ] He has authored book chapters, and is an editor for the Handbook of Proteins: Structure, Function and Methods Volume 2 . He is the recipient of the Arnold O. Beckman Research Award, the American Heart Association's Established Investigator Award, and the Vilas Associate Award. [ 4 ]
Phillips is an Elected Fellow of the Biophysical Society , the American Crystallographic Association , and the American Association for the Advancement of Science . [ 5 ] He served as president and vice-president of the American Crystallographic Association from 2011 to 2013. [ 6 ] He also holds the position of Editor-in-Chief for Structural Dynamics with the AIP Press [ 7 ] and serves as an Associate Editor for Critical Reviews in Biochemistry and Molecular Biology . [ 8 ]
Phillips obtained his bachelor's degree in Biochemistry and Chemistry from Rice University in 1974 and followed it with a Ph.D. in biochemistry from the same institution in 1976. [ 9 ] He also held a Robert A. Welch Predoctoral Fellowship from 1974 to 1976 and received a Postdoctoral Fellowship from the National Institutes of Health in 1977 as well as a Research Fellowship from the Medical Foundation in 1980. [ 10 ]
Phillips started his academic career as an assistant professor at the University of Illinois Urbana-Champaign , followed by his appointment as a professor of biochemistry at Rice University in 1987. [ 11 ] In 1993, he assumed the position of Rice Scientia Lecturer, subsequently receiving the Robert A. Welch Lecturer appointment in 2001. He joined the University of Wisconsin-Madison in 2000 as a professor of Biochemistry and took on the role of professor emeritus in 2012. [ 12 ] He has been serving as a professor of chemistry, as well as the Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology at Rice University. [ 13 ]
Phillips has directed his research toward the field of computational biology , primarily exploring protein structure . In the Phillips Lab, his work has involved conducting research on the binding of oxygen and ligands to heme proteins, as well as the development of techniques for analyzing protein and nucleic acid dynamics through diffuse X-ray scattering analysis. [ 14 ]
Phillips conducted various studies on protein structures and their functional implications. He examined the structural features of type 6 streptococcal M proteins, highlighting their predominantly alpha-helical coiled-coil, which demonstrates a unique conformation in bacterial surface projections. [ 10 ] His research on the crystal structure of tropomyosin filaments proposed a model in which tropomyosin exhibited distinct conformations related to muscle contraction, suggesting a statistical mechanism for regulating muscle function. [ 15 ]
In one of his highly cited studies, Phillips, alongside Fan Yang and Larry G. Moss, described the crystal structure of recombinant wild-type green fluorescent protein, unveiling a unique structure referred to as the "ß-can." This study also delved into the protective environment for the fluorophores within the cylinder and its applications in elucidating the effects of GFP mutants. [ 16 ]
Phillips has utilized X-ray crystallography and various advanced spectroscopy techniques to provide details about the dynamic structural changes in proteins. He used X-ray crystallography to determine the structure of unstable intermediate caused by photodissociation of CO from myoglobin and provided insights into the dynamics and structural alterations involved in this protein reaction. [ 17 ] In addition, his study focused on capturing the structural evolution of the protein on a picosecond timescale used time-resolved X-ray diffraction and mid-infrared spectroscopy on a myoglobin (Mb) mutant (L29F mutant) revealing conformational changes within the protein. [ 18 ]
Phillips' research on heme proteins and ligand affinity has provided insights into engineering strategies for physiological functions. He explored the impact of His64 in sperm whale myoglobin on ligand affinity, shedding light on structural changes induced by ligand binding and mechanisms of ligand discrimination in myoglobin. [ 19 ] By measuring CO binding properties in various mutants and comparing them to mutant myoglobins, he elucidated how mutations influence CO affinity. [ 20 ] In his 1994 study, he delved into how heme proteins like myoglobin and hemoglobin differentiate between oxygen (O2) and carbon monoxide (CO) binding at the atomic level. [ 21 ] He investigated the role of nitric oxide in physiological functions by examining the kinetics of NO-induced oxidation in myoglobins and hemoglobins revealing insights into protein engineering strategies aimed at mitigating hypertensive events. [ 22 ]
Phillips' contributions to computational biology include advanced techniques for interpreting experimental data in complex chemical and biological systems. He focused on the interaction between troponin T (TnT) and tropomyosin, shedding light on the molecular mechanisms in muscle contractions. [ 23 ] Additionally, he explored protein dynamics in crystals by using the Gaussian network model (GNM) and a crystallographic model to calculate Cα atom fluctuations in 113 proteins emphasizing the improved results obtained by considering neighboring molecules in the crystal. [ 24 ] In a book chapter discussing ongoing advancements in experimental methods for complex chemical and biological systems, he highlighted the growing need for creative approaches and delved into the exploration of Normal Mode Analysis as a technique to address these challenges. [ 25 ] | https://en.wikipedia.org/wiki/George_N._Phillips |
George Porter, Baron Porter of Luddenham , OM , FRS , FRSE (6 December 1920 – 31 August 2002) was a British chemist . [ 5 ] He was awarded the Nobel Prize in Chemistry in 1967.
Porter was born in Stainforth , near Thorne , in the then West Riding of Yorkshire . He was educated at Thorne Grammar School , [ 6 ] then won a scholarship to the University of Leeds and gained his first degree in chemistry . During his degree, Porter was taught by Meredith Gwynne Evans , who he later said was the most brilliant chemist he had ever met. He was awarded a PhD from the University of Cambridge in 1949 for research investigating free radicals produced by photochemical means . [ 7 ] He would later become a fellow at Emmanuel College, Cambridge . [ 8 ]
Porter served in the Royal Naval Volunteer Reserve during the Second World War . Porter then went on to do research at the University of Cambridge supervised by Ronald George Wreyford Norrish where he began the work that ultimately led to them becoming Nobel Laureates .
His original research in developing the technique of flash photolysis to obtain information on short-lived molecular species provided the first evidence of free radicals . His later research utilised the technique to study the detailed aspects of the light-dependent reactions of photosynthesis , with particular regard to possible applications to a hydrogen economy , of which he was a strong advocate.
He was Assistant Director of the British Rayon Research Association from 1953 to 1954, where he studied the phototendering of dyed cellulose fabrics in sunlight. [ 9 ]
Porter served as professor in the Chemistry department at the University of Sheffield in 1954–65. It was here he started his work on flash photolysis with equipment designed and made in the departmental workshop. During this tenure he also took part in a television programme describing his work. This was in the "Eye on Research" series. Porter became Fullerian Professor of Chemistry and Director of the Royal Institution in 1966. During his directorship of the Royal Institution, Porter was instrumental in the setting up of Applied Photophysics, a company created to supply instrumentation based on his group's work. He was awarded the Nobel Prize in Chemistry in 1967 along with Manfred Eigen and Ronald George Wreyford Norrish . [ 10 ] In the same year he became a visiting professor at University College London . [ 10 ]
Porter was a major contributor to the Public Understanding of science . He became president of the British Association in 1985 and was the founding Chair of the Committee on the Public Understanding of Science (COPUS). He gave the Romanes Lecture , entitled "Science and the human purpose", at the University of Oxford in 1978; and in 1988 he gave the Dimbleby Lecture , "Knowledge itself is power." From 1990 to 1993 he gave the Gresham lectures in astronomy.
Porter was elected a Fellow of the Royal Society (FRS) in 1960 , [ 1 ] a member of the American Academy of Arts and Sciences in 1979, [ 11 ] a member of the American Philosophical Society in 1986, [ 12 ] and served as President of the Royal Society from 1985 to 1990. He was also awarded the Davy Medal in 1971, the Rumford Medal in 1978, the Ellison-Cliffe Medal in 1991 and the Copley Medal in 1992.
Porter also received an Honorary Doctorate from Heriot-Watt University in 1971. [ 13 ]
He was knighted in 1972, appointed to the Order of Merit in 1989, [ 14 ] and was made a life peer as Baron Porter of Luddenham , of Luddenham in the County of Kent , in 1990. In 1995, he was awarded an Honorary Degree (Doctor of Laws) from the University of Bath . [ 15 ]
In 1976 he gave the Royal Institution Christmas Lecture on The Natural History of a Sunbeam . [ 16 ]
Porter served as Chancellor of the University of Leicester between 1984 and 1995. In 2001, the university's chemistry building was named the George Porter Building in his honour.
In 1949 Porter married Stella Jean Brooke. | https://en.wikipedia.org/wiki/George_Porter |
George Rosenkranz (born György Rosenkranz ; 20 August 1916 – 23 June 2019) was a pioneering Hungarian-born Mexican scientist in the field of steroid chemistry , who used native Mexican plant sources as raw materials. [ 2 ] [ 3 ] He was born in Hungary, studied in Switzerland and emigrated to the Americas to escape the Nazis , eventually settling in Mexico. [ 2 ] [ 4 ]
At Syntex corporation in Mexico City, Rosenkranz assembled a research group of organic chemists that included future leaders from around the world, such as Carl Djerassi , Luis E. Miramontes and Alejandro Zaffaroni . [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] Revolutionary advances in the understanding of steroid drugs and their production occurred under Dr Rosenkranz's direction. [ 11 ] Syntex synthesized a progestin used in some of the first combined oral contraceptive pills and numerous other useful steroids. Under Rosenkranz's leadership, Syntex became "a powerful international force in the development of steroidal pharmaceuticals", [ 12 ] and "a pioneer of biotechnology" in the San Francisco Bay Area. Rosenkranz stepped down as CEO in 1982, at the age of 65. [ 13 ]
In 2012, he was awarded the Biotechnology Heritage Award , in recognition of his significant contributions to the development of biotechnology through discovery, innovation, and public understanding. [ 8 ] He turned 100 in August 2016. [ 14 ]
Rosenkranz was also an American Contract Bridge League (ACBL) Grand Life Master at his hobby of duplicate bridge , with more than 13,000 masterpoints and 12 NABC titles ( below ). He wrote or co-wrote more than 10 books on bridge. [ 15 ]
Rosenkranz was born in 1916 in Budapest, Hungary, [ 13 ] the son of Etel (Weiner) and Bertalan Rosenkranz. [ 16 ] Rosenkranz studied chemical engineering at the Swiss Federal Institute of Technology , where he received his doctorate . [ 13 ] His mentor, future Nobel Prize winner Lavoslav Ružička , began Rosenkranz's interest in steroid research. However, Nazi sympathizers were active in Zurich . Ružička shielded Rosenkranz and other Jewish colleagues, but their presence put their mentor at risk. "We got together and we decided to leave Switzerland to protect him," Rosenkranz said in a 2002 article for the Pan American Health Organization's magazine. [ 4 ]
Ružička arranged an academic position for Rosenkranz in Quito , Ecuador. While Rosenkranz was waiting in Havana , Cuba, for a ship to Ecuador, the Japanese attacked Pearl Harbor . The United States immediately entered World War II. Unable to go to Ecuador, Rosenkranz accepted the Cuban president Fulgencio Batista 's offer allowing refugees to stay in the country and work. He found work at the Vieta Plasencia Lab, where he was asked to develop treatments for venereal disease . [ 3 ]
The important role of hormones in human health was already known, but ways to synthesize them were unknown. George Rosenkranz's skills as a chemist attracted the interest of Emeric Somlo , a Hungarian immigrant, and Dr. Federico Lehmann at Syntex in Mexico City, Mexico. [ 17 ] They had formed the company in 1944 to work with Russell Marker , a Penn State professor, and sought to synthesize the hormone progesterone from diosgenin -containing Mexican yams, which would eventually give rise to the Mexican barbasco trade . [ 18 ] : 183 After a disagreement Marker left, taking his steroid knowledge with him. Rosenkranz was recruited to replace him, and moved to Mexico City in 1945. [ 4 ] [ 5 ]
Rosenkranz faced the challenge of analyzing Marker's samples to identify their ingredients and reverse engineering Marker's chemical production processes. He didn't have much help: his initial staff included nine lab assistants and only one other chemist, [ 19 ] and Mexico lacked a PhD program in chemistry. [ 20 ]
When he couldn't find enough fully trained local chemists, Rosenkranz recruited researchers from Mexico and around the world. Rosenkranz also helped to create an institute of chemistry, the Instituto de Química ( Universidad Nacional Autónoma de México ), now considered "a flagship in Mexico's ethnobotanical research". [ 21 ] He was able to attract significant synthetic organic chemists as researchers and instructors and to obtain funding to expand programs for the training of organic chemists. He and his colleagues regularly worked at Syntex during the day and then spent the evenings teaching chemistry. Rosenkranz also helped to start the Institute for Molecular Biology in Palo Alto . [ 20 ]
Attracting young chemists such as Carl Djerassi , Luis E. Miramontes and Alejandro Zaffaroni was critical to Syntex's first big success. [ 5 ] [ 6 ] Miramontes, George Rosenkranz and Djerassi synthesis of norethindrone, later proven to be an effective pregnancy inhibitor, led to an infusion of capital in Syntex and Mexican steroid pharma industry. [ 22 ] The Mayo clinic had reported that the steroid hormone cortisone was an effective anti-inflammatory, capable of relieving painful rheumatoid arthritis symptoms. However, as described by Djerassi, "Until 1951, the only source of cortisone was through an extraordinarily complex process of 36 different chemical transformations starting from animal bile acids." [ 23 ] Several prominent groups of international scientists were attempting to be the first to synthesize cortisone. Rosenkranz's team started working in two shifts, and their dedication paid off. In 1951, Rosenkranz, Djerassi, and their fellow researchers submitted a paper on the synthesis of cortisone, edging out reports from Harvard and Merck by a matter of weeks. [ 9 ] [ 24 ] [ 25 ] [ 26 ]
Having successfully synthesized cortisone, the researchers at Syntex continued to work on the synthesis of progesterone. A female sex hormone, progesterone was used to help pregnant women avoid miscarriages, and to treat infertility. [ 23 ] Five months later, under the direction of Rosenkranz and Djerassi, the last step of the synthesis of norethisterone (norethindrone) was successfully completed by Miramontes, and Syntex applied for a patent, which was granted as US patent 2,744,122 on May 1, 1956. [ 4 ] [ 25 ] [ 27 ] Syntex initially reached an agreement with the American company Parke-Davis to market norethisterone as Norlutin for the treatment of gynecological disorders, which was approved by the FDA in 1957. [ 28 ] Parke-Davis however refused to develop Syntex's norethisterone as a contraceptive over concerns about a possible Catholic boycott of its other products. [ 29 ] This delay placed Syntex at a disadvantage, but by 1962, they had partnered with Johnson & Johnson 's Ortho division to introduce the birth control pill Ortho-Novum , which used Syntex's norethisterone. [ 20 ] [ 28 ] [ 30 ] In March 1964, the FDA approved Syntex's version of Ortho-Novum with the brand name Norinyl (norethisterone 2 mg + mestranol 100 μg). [ 20 ] [ 30 ] [ 31 ] In March 1964, the FDA also approved Parke-Davis's version of the German company Schering 's oral contraceptive Anovlar with the brand name Norlestrin ( norethisterone acetate 2.5 mg + ethinylestradiol 50 μg). [ 31 ]
Rosenkranz understood the importance of peer recognition, not just commercial success, to the scientists who worked for him. He has said, "To have people work productively, you have to build an intellectually challenging environment, allow creative freedom, and insure peer recognition and respect for the individual." [ 32 ] A cascade of papers on steroid chemistry issued from the Rosenkranz lab during the 1940s and 1950s. [ 9 ] [ 20 ] Rosenkranz himself is the author or co-author of over 300 articles in steroid chemistry and is named on over 150 patents. [ 8 ]
Rosenkranz gave up his executive positions at Syntex in 1981. [ 8 ] Although technically retired for over three decades, Rosenkranz was still active in the industry. In 1996, he became a member of the board of Digital Gene Technologies [ 33 ] He was also president of the advisory board of ICT Mexicana. [ 32 ] He died at the age of 102 on 23 June 2019. [ 16 ]
Rosenkranz was a world-class bridge player and one of the most successful in Mexico. He won 12 NABC-level events at thrice-annual North American Bridge Championships meets, including all four major teams-of-four titles: the Grand Nationals , Reisinger , Spingold and Vanderbilt . In world championship teams competition, he represented Mexico in the quadrennial World Team Olympiad three times from 1972 to 1996 and the United States in the 1983 Bermuda Bowl . [ 38 ] In addition, he has made significant contributions to bidding theory. He created the Romex bidding system, an extension of Standard American with many gadgets. He invented the Rosenkranz double and Rosenkranz redouble, [ 39 ] and wrote more than a dozen books on bridge. [ 4 ]
In July 1984, Rosenkranz' wife Edith was kidnapped at the summer North American Bridge Championships in Washington, D.C., by Glenn I. Wright and Dennis Moss, and ransomed for one million dollars. The FBI and the District of Columbia police captured Wright and Moss, and she was returned safely. [ 40 ] The ransom money was later recovered and the two kidnappers were later convicted and sentenced, as was a third defendant, Orland D. Tolden. [ 41 ] [ circular reference ] Wright was released in 1999, Moss in 1994, and Tolden in 1989. [ 42 ]
The four Godfrey books combine fictional narrative and instructional bridge. The second, and first with co-author credit to Phillip Alder, Godfrey's Bridge Challenge "brings the Romex system to life through lively anecdotes instruction and quizzes". The last, Godfrey's Angels incorporates 1998–2001 improvements in the system. [ 44 ] [ 45 ] | https://en.wikipedia.org/wiki/George_Rosenkranz |
George Simms Hammond (May 22, 1921 – October 5, 2005) was an American scientist and theoretical chemist who developed " Hammond's postulate ", and fathered organic photochemistry , [ 1 ] [ 2 ] [ 3 ] –the general theory of the geometric structure of the transition state in an organic chemical reaction . Hammond's research is also known for its influence on the philosophy of science . [ 4 ] His research garnered him the Norris Award in 1968, the Priestley Medal in 1976, the National Medal of Science in 1994, [ 5 ] and the Othmer Gold Medal in 2003. [ 6 ] [ 7 ] He served as the executive chairman of the Allied Chemical Corporation from 1979 to 1989.
He was a chemist at the California Institute of Technology , and subsequently headed both the Departments of Chemistry and Chemical Engineering at the university. He conducted research at the University of Oxford and University of Basel as a Guggenheim Fellow and National Science Foundation Fellow , respectively. He served as the foreign secretary of the National Academy of Sciences from 1974 to 1978.
A native of Maine , he was born and raised in Auburn ; he attended nearby Bates College in Lewiston, Maine , where he graduated magna cum laude with a B.S. in chemistry in 1943. He completed his doctorate at Harvard University in 1947, under the mentorship of Paul Doughty Bartlett , and a postdoctorate at University of California, Los Angeles with Saul Winstein in 1948.
George Simms Hammond was born on May 22, 1921, in Auburn, Maine . [ 1 ] Growing up in Auburn his family were charged with the operation of the neighborhood dairy farm on Hardscrabble Road. His father died when Hammond was thirteen. He was the oldest of seven children and was raised by a single mother. From an early age Hammond was charged with running the day-to-day operations of the dairy farm with his mother and older siblings. [ 1 ] Hammond's parents were college graduates, but disliked the local schools in Auburn. [ 8 ] As a result, he was homeschooled until the sixth grade. Afterwards, he was educated at various Auburn public schools before graduating in 1938. After graduating he took a gap year to continue operating his dairy farm. After his educational hiatus he applied to and was accepted into Bates College , in Lewiston, Maine . He graduated with a Bachelors of Science in chemistry magna cum laude and Phi Beta Kappa in January 1943. [ 1 ]
Upon graduating from college, Hammond took a position as a chemist at Rohm and Haas in Philadelphia, Pennsylvania . After some months on the job he quit to pursue graduate studies at Harvard University , where he received a Masters of Science (M.S.) and Doctor of Philosophy (Ph.D.). [ 1 ] His thesis, Inhibition of the Polymerization of Allylacetate , was supervised by Paul Doughty Bartlett . Hammond then moved to Los Angeles, California , to study intermolecular compounds at UCLA . [ 1 ]
His academic career began in 1948 with a teaching position at Iowa State College ; he served as Assistant Professor of Chemistry. In his capacity there he published his eponymous postulate which is now widely known as the most important publication in the field of organic photochemistry . [ 1 ] [ 2 ] [ 3 ] He moved to the University of Oxford and University of Basel as a Guggenheim Fellow and National Science Foundation Fellow , respectively. [ 1 ] In 1958, he moved to the California Institute of Technology as a Professor of Organic Chemistry. Later he was appointed the Arthur Amos Noyes Professor of Chemistry and subsequently went on to lead the Departments of Chemistry and Chemical Engineering. After 14 years teaching and serving as an academic administrator at Caltech he moved in 1972 to the University of California Santa Cruz . At University of California Santa Cruz he served as both a professor and the Chancellor of the natural sciences. [ 1 ] [ 9 ]
Aside from the academic world, during all these years, George Hammond, "made many public speeches on controversial themes, both political (e.g., the invasion of Cambodia, delivered in 1971 at a public rally on Caltech's Olive Walk) and scientific (e.g., the future of chemistry)" [ 8 ] Many of these controversial speeches affected his career negatively. For example, after his speech at Olive Walk, president Richard Nixon's administration removed his name from nomination for a major NSF post. [ 8 ] Nevertheless, he did not back down and continued to criticize the government, and not limiting to delivering speeches, he wrote a letter to the editor of a newspaper saying: “A June 30 front-page article describes the potential bonanza in arms sales to new members as the North Atlantic Treaty Organization expands. I was favorably inclined toward expansion because of my naive assumption that bringing most of the nations of Europe and North America together as a cooperating group would decrease the likelihood of war. I cannot believe this will be the case if a prerequisite for entry is that countries buy new armaments from present members. At whom will the guns be aimed? Russia? Then we will probably re-create the cold war." [ 10 ] The way this excerpt was written says many things about George Hammond, starting with his passionate character. Hammond fought for everything he believed in. He cared about his nation and he was also a little reckless about the consequences he could suffer for defying the government. Also, in the excerpt, a sarcastic side of Hammond can be perceived, a man of strong character with the ability to recognize when he is wrong.
He was appointed as the Foreign Secretary of the National Academy of Sciences in 1974 and served for one term retiring in 1978. He also gave notable speeches on political issues such as the invasion of Cambodia , [ 1 ] and various topics on Chemistry. The talks he gave sometimes had negative impacts on his life, exemplified by Nixon's withdrawal of his name for major National Science Foundation positions. In 1979 he retired from academia and joined the Allied Chemical Corporation as Executive Chairman , serving for ten years. He retired from this capacity and all others after his tenure concluded. [ 1 ]
George Hammond published a hypothesis in physical organic chemistry which describes the geometric structure of the transition state in an organic chemical reaction in his publication, Hammond's principle.
His 1955 publication asserted:
"If two states, as, for example, a transition state and an unstable intermediate, occur consecutively during a reaction process and have nearly the same energy content, their interconversion will involve only a small reorganization of the molecular structures." [ 11 ]
Therefore, the geometric structure of a state can be predicted by comparing its energy to the species neighboring it along the reaction coordinate . For example, in an exothermic reaction the transition state is closer in energy to the reactants than to the products. Therefore, the transition state will be more geometrically similar to the reactants than to the products. In contrast, however, in an endothermic reaction the transition state is closer in energy to the products than to the reactants. So, according to Hammond's postulate the structure of the transition state would resemble the products more than the reactants. [ 12 ] This type of comparison is especially useful because most transition states cannot be characterized experimentally. [ 13 ]
Hammond's postulate also helps to explain and rationalize the Bell–Evans–Polanyi principle . Namely, this principle describes the experimental observation that the rate of a reaction , and therefore its activation energy , is affected by the enthalpy change of that reaction. Hammond's postulate explains this observation by describing how varying the enthalpy of a reaction would also change the structure of the transition state. In turn, this change in geometric structure would alter the energy of the transition state, and therefore the activation energy and reaction rate as well. [ 14 ]
The postulate has also been used to predict the shape of reaction coordinate diagrams. For example, electrophilic aromatic substitutions involves a distinct intermediate and two less well defined states. By measuring the effects of aromatic substituents and applying Hammond's postulate it was concluded that the rate-determining step involves formation of a transition state that should resemble the intermediate complex. [ 15 ]
During the 1940s and 1950s, chemists had trouble explaining why even slight changes in the reactants caused significant differences in the rate and product distributions of a reaction. In 1955 George S. Hammond, a young professor at Iowa State University , postulated that transition-state theory could be used to qualitatively explain the observed structure-reactivity relationships. [ 2 ] Notably, John E. Leffler of Florida State University proposed a similar idea in 1953. [ 3 ] However, Hammond's version has received more attention since its qualitative nature was easier to understand and employ than Leffler's complex mathematical equations. Hammond's postulate is sometimes called the Hammond-Leffler postulate to give credit to both scientists. [ 2 ]
Effectively, the postulate states that the structure of a transition state resembles that of the species nearest to it in free energy . This can be explained with reference to potential energy diagrams:
In case (a), which is an exothermic reaction, the energy of the transition state is closer in energy to that of the reactant than that of the intermediate or the product. Therefore, from the postulate, the structure of the transition state also more closely resembles that of the reactant. In case (b), the energy of the transition state is close to neither the reactant nor the product, making none of them a good structural model for the transition state. Further information would be needed in order to predict the structure or characteristics of the transition state. Case (c) depicts the potential diagram for an endothermic reaction, in which, according to the postulate, the transition state should more closely resemble that of the intermediate or the product.
Another significance of Hammond's postulate is that it permits us to discuss the structure of the transition state in terms of the reactants, intermediates, or products. In the case where the transition state closely resembles the reactants, the transition state is called “early” while a “late” transition state is the one that closely resembles the intermediate or the product. [ 16 ]
An example of the “early” transition state is chlorination. Chlorination favors the products because it is an exothermic reaction, which means that the products are lower in energy than the reactants. [ 17 ] When looking at the adjacent diagram (representation of an "early" transition state), one must focus on the transition state, which is not able to be observed during an experiment. To understand what is meant by an “early” transition state, the Hammond postulate represents a curve that shows the kinetics of this reaction. Since the reactants are higher in energy, the transition state appears to be right after the reaction starts.
An example of the “late” transition state is bromination. Bromination favors the reactants because it is an endothermic reaction, which means that the reactants are lower in energy than the products. [ 18 ] Since the transition state is hard to observe, the postulate of bromination helps to picture the “late” transition state (see the representation of the "late" transition state). Since the products are higher in energy, the transition state appears to be right before the reaction is complete.
One other useful interpretation of the postulate often found in textbooks of organic chemistry is the following:
This interpretation ignores extremely exothermic and endothermic reactions which are relatively unusual and relates the transition state to the intermediates which are usually the most unstable.
Hammond's postulate can be used to examine the structure of the transition states of a SN1 reaction . In particular, the dissociation of the leaving group is the first transition state in a S N 1 reaction. The stabilities of the carbocations formed by this dissociation are known to follow the trend tertiary > secondary > primary > methyl.
Therefore, since the tertiary carbocation is relatively stable and therefore close in energy to the R-X reactant, then the tertiary transition state will have a structure that is fairly similar to the R-X reactant. In terms of the graph of reaction coordinate versus energy, this is shown by the fact that the tertiary transition state is further to the left than the other transition states. In contrast, the energy of a methyl carbocation is very high, and therefore the structure of the transition state is more similar to the intermediate carbocation than to the R-X reactant. Accordingly, the methyl transition state is very far to the right.
Substitution, nucleophilic bimolecular reactions are concerted reactions where both the nucleophile and substrate are involved in the rate limiting step. Since this reaction is concerted, the reaction occurs in one step, where the bonds are broken, while new bonds are formed. [ 19 ] Therefore, to interpret this reaction, it is important to look at the transition state, which resembles the concerted rate limiting step. In the "Depiction of S N 2 Reaction" figure, the nucleophile forms a new bond to the carbon, while the halide (L) bond is broken. [ 20 ]
An E1 reaction consists of a unimolecular elimination, where the rate determining step of the mechanism depends on the removal of a single molecular species. This is a two-step mechanism. The more stable the carbocation intermediate is, the faster the reaction will proceed, favoring the products. Stabilization of the carbocation intermediate lowers the activation energy. The reactivity order is (CH3)3C- > (CH3)2CH- > CH3CH2- > CH3-. [ 21 ]
Furthermore, studies describe a typical kinetic resolution process that starts out with two enantiomers that are energetically equivalent and, in the end, forms two energy-inequivalent intermediates, referred to as diastereomers. According to Hammond's postulate, the more stable diastereomer is formed faster. [ 22 ]
Elimination, bimolecular reactions are one step, concerted reaction where both base and substrate participate in the rate limiting step. In an E2 mechanism, a base takes a proton near the leaving group, forcing the electrons down to make a double bond, and forcing off the leaving group-all in one concerted step. The rate law depends on the first order concentration of two reactants, making it a 2nd order (bimolecular) elimination reaction. Factors that affect the rate determining step are stereochemistry, leaving groups, and base strength.
A theory, for an E2 reaction, by Joseph Bunnett suggests the lowest pass through the energy barrier between reactants and products is gained by an adjustment between the degrees of C β -H and C α -X rupture at the transition state. The adjustment involves much breaking of the bond more easily broken, and a small amount of breaking of the bond which requires more energy. [ 23 ] This conclusion by Bunnett is a contradiction from the Hammond postulate. The Hammond postulate is the opposite of what Bunnett theorized. In the transition state of a bond breaking step it involves little breaking when the bond is easily broken and much breaking when it is difficult to break. [ 23 ] Despite these differences, the two postulates are not in conflict since they are concerned with different sorts of processes. Hammond focuses on reaction steps where one bond is made or broken, or the breaking of two or more bonds occur simultaneously. The E2 theory transition state concerns a process when bond formation or breaking are not simultaneous. [ 23 ]
Technically, Hammond's postulate only describes the geometric structure of a chemical reaction. However, Hammond's postulate indirectly gives information about the rate , kinetics , and activation energy of reactions. Hence, it gives a theoretical basis for the understanding the Bell-Evans-Polanyi principle , which describes the experimental observation that the enthalpy change and rate of similar reactions were usually correlated.
The relationship between Hammond's postulate and the BEP principle can be understood by considering a S N 1 reaction . Although two transition states occur during a S N 1 reaction (dissociation of the leaving group and then attack by the nucleophile), the dissociation of the leaving group is almost always the rate-determining step . Hence, the activation energy and therefore rate of the reaction will depend only upon the dissociation step.
First, consider the reaction at secondary and tertiary carbons. As the BEP principle notes, experimentally S N 1 reactions at tertiary carbons are faster than at secondary carbons. Therefore, by definition, the transition state for tertiary reactions will be at a lower energy than for secondary reactions. However, the BEP principle cannot justify why the energy is lower.
Using Hammond's postulate, the lower energy of the tertiary transition state means that its structure is relatively closer to its reactants R(tertiary)-X than to the carbocation "product" when compared to the secondary case. Thus, the tertiary transition state will be more geometrically similar to the R(tertiary)-X reactants than the secondary transition state is to its R(secondary)-X reactants. Hence, if the tertiary transition state is close in structure to the (low energy) reactants, then it will also be lower in energy because structure determines energy . Likewise, if the secondary transition state is more similar to the (high energy) carbocation "product," then it will be higher in energy.
Hammond's postulate is useful for understanding the relationship between the rate of a reaction and the stability of the products. While the rate of a reaction depends just on the activation energy (often represented in organic chemistry as ΔG ‡ “delta G double dagger”), the final ratios of products in chemical equilibrium depends only on the standard free-energy change Δ G (“delta G ”). The ratio of the final products at equilibrium corresponds directly with the stability of those products.
Hammond's postulate connects the rate of a reaction process with the structural features of those states that form part of it, by saying that the molecular reorganizations have to be small in those steps that involve two states that are very close in energy. This gave birth to the structural comparison between the starting materials, products, and the possible "stable intermediates" that led to the understanding that the most stable product is not always the one that is favored in a reaction process.
Hammond's postulate is especially important when looking at the rate-limiting step of a reaction. However, one must be cautious when examining a multistep reaction or one with the possibility of rearrangements during an intermediate stage. In some cases, the final products appear in skewed ratios in favor of a more unstable product (called the kinetic product ) rather than the more stable product (the thermodynamic product ). In this case one must examine the rate-limiting step and the intermediates. Often, the rate-limiting step is the initial formation of an unstable species such as a carbocation . Then, once the carbocation is formed, subsequent rearrangements can occur. In these kinds of reactions, especially when run at lower temperatures, the reactants simply react before the rearrangements necessary to form a more stable intermediate have time to occur. At higher temperatures when microscopic reversal is easier, the more stable thermodynamic product is favored because these intermediates have time to rearrange. Whether run at high or low temperatures, the mixture of the kinetic and thermodynamic products eventually reach the same ratio, one in favor of the more stable thermodynamic product, when given time to equilibrate due to microreversal.
Hammond married Marian Reese in 1945, and had five children with her. The couple divorced in 1975, and he was remarried soon after to Eve Menger. He had two children with Eve. [ 1 ] | https://en.wikipedia.org/wiki/George_S._Hammond |
George Streisinger (December 27, 1927 – August 11, 1984) was an American molecular biologist and co-founder of the Institute of Molecular Biology at the University of Oregon . [ 1 ] He was the first person to clone a vertebrate, cloning zebrafish in his University of Oregon laboratory. [ 2 ] He also pioneered work in the genetics of the T-even bacterial viruses. In 1972, along with William Franklin Dove he was awarded a Guggenheim Fellowship award, and in 1975 he was selected as a member of the National Academy of Sciences , making him the second Oregonian to receive the distinction. [ 3 ] The University of Oregon's Institute of Molecular Biology named their main building "Streisinger Hall" in his honor. [ 4 ]
George Streisinger was born in Budapest , Hungary , on December 27, 1927. Because they were Jewish, in 1937, his family left Budapest for New York to escape Nazi persecution. Streisinger attended New York public schools and graduated from the Bronx High School of Science in 1944. He obtained a B.S. degree from Cornell University in 1950, and a Ph.D. from the University of Illinois in 1953. He completed postdoctoral studies at the California Institute of Technology from 1953 to 1956. He married Lotte Sielman in 1949. Streisinger accepted a post at the University of Oregon Institute of Molecular Biology in Eugene in 1960. Streisinger was well known as an innovative professor in and out of the classroom, conscripting a dance class to illustrate protein synthesis, and often requested beginning and non-major biology students. He was very politically active, organizing grass-roots resistance to the Vietnam war and legislative opposition to John Kennedy's civil defense program . He testified to successfully ban mutagenic herbicides in Douglas fir reforestation, and led and won a battle to exclude secret war department research from the University of Oregon campus.
His wife, Lotte, was a noted artist and community activist, and the founder of the Eugene Saturday Market , the inspiration for the Portland Oregon Saturday Market. [ 5 ] [ 6 ]
Following his graduation from Cornell, George under- took graduate studies in the genetics of T-even coliphage with Salvador Luria in the Bacteriology Department of the University of Illinois. His studies revealed phenotypic mixing, in which a phage with a host-range genotype of one phage type was found in a particle who was phenotypically dissimilar. When published in 1956, these studies had profound impact on the study of viral biology.
During his postdoc at Caltech, with Jean Weigle , he undertook further studies on T2 × T4 hybrids, which led to the discovery of DNA modification (by glucosylation).
At the University of Oregon, Streisinger pioneered the study of zebrafish in his lab. Zebrafish can be genetically modified easily, and researchers can modify them to mimic the traits of certain diseases. In analyzing these created diseases, scientists seek solutions to diseases which affect humans. Over 9,000 researchers [ 7 ] in 1,551 labs [ 8 ] throughout 31 countries study zebrafish , and many of them received their initial training at the University of Oregon. [ 9 ] | https://en.wikipedia.org/wiki/George_Streisinger |
The George Van Biesbroeck Prize is an award for long-term achievements in the field of astronomy . According to the American Astronomical Society awards website; "The Van Biesbroeck prize is normally awarded every two years and honors a living individual for long-term extraordinary or unselfish service to astronomy, often beyond the requirements of his or her paid position."
From 1979 to 1996 the award was presented by Van Biesbroeck Award, Inc. The American Astronomical Society assumed responsibility for the Prize in 1997.
The prize is named after George Van Biesbroeck who himself continued to work as an active astronomer for 27 years after "retirement" at age 65.
Winners of the award have been: [ 1 ] | https://en.wikipedia.org/wiki/George_Van_Biesbroeck_Prize |
George Warren Hammond (April 4, 1833 – January 6, 1908) [ 1 ] was an American businessman. Camp Hammond , in Yarmouth, Maine , is named for him. He was also one of its architects. Built in 1889 (136 years ago) ( 1889 ) , it was placed on the National Register of Historic Places in 1979. [ 2 ]
Hammond was also co-owner of Forest Paper Company , which was the largest paper mill in the world at the time of his death. The mill was also known as a pioneer in the processing of soda pulp .
Hammond was born on April 4, 1833, in Grafton, Massachusetts , [ 1 ] to Josiah and Anna Warren. One of his siblings, William Henry (1841–1908), followed him to Maine. He worked in Portland until his death, a few months after George, at the age of 67. His body was returned to the family's hometown of Grafton for interment. [ 3 ]
He received an honorary degree of Master of Arts degree from Bowdoin College in 1900. [ 4 ]
After finishing school, Hammond began working at Howe & Leeds Wholesale West India Goods Store on Boston 's Long Wharf . The same year, he became a clerk with J. W. Blodgett & Co.
Hammond attended the Massachusetts Institute of Technology as a special student on the chemistry of paper manufacturing. [ 4 ]
After moving to Maine part-time, in 1853 he accepted a position at his uncle Samuel Dennis Warren's S. D. Warren Paper Mill in Cumberland Mills . By 1857, he was superintendent, a role in which remained for five years. His next position was as the mill's agent. [ 1 ]
In 1874, Hammond and Warren bought the rights to Yarmouth Paper Company, in Yarmouth, Maine , at the town's Third Falls . They renamed it Forest Paper Company. Beginning with a single wooden building, the facility expanded to ten buildings covering as many acres, including a span over the Royal River to Factory Island. Two bridges to it were also constructed. In 1909, the year following Hammond's death, it was the largest such mill in the world, employing 275 people. [ 1 ] [ 5 ] Hammond also worked at the S. D. Warren mill until 1876, before transferring full-time to Yarmouth as the manager of the new business. [ 1 ] The mill became known as a pioneer in the processing of soda pulp . [ 4 ]
Hammond retired from active business on January 1, 1906. [ 4 ]
Hammond married Ellen Sarah Sophia Clarke (1833–1905), the sister-in-law of Samuel Warren, in 1874. [ 1 ] Hammond survived her by three years upon her death in 1905.
Along with New York architect Alexander Twombly, [ 6 ] who was the engineer and draftsman of Forest Paper Company, Hammond designed what is today known as Camp Hammond , [ 1 ] set back from Yarmouth's Main Street and from which Hammond could see his mill. Twombly also designed several buildings in Boston. [ 7 ] Frederick Law Olmsted , who designed Central Park in New York City, designed the gardens of the property. [ 8 ] With the Hammonds splitting their time between Boston and Yarmouth, the property became known as the Camp . [ 1 ]
The Hammonds also formed the Antiquarian Society in order to facilitate the 1890 purchase of the North Yarmouth and Freeport Baptist Meetinghouse on Yarmouth's Hillside Street. [ 1 ] It became a library and museum, known as the Hillside Library. [ 9 ]
Among the many roles Hammond took on without payment was as president of the Yarmouth Water Committee , [ 1 ] established in 1895, which sourced its water supply from Hammond Spring on the property of Forest Paper Company. [ 10 ] Hammond donated Forest Paper Company land for the 1903 construction of Merrill Memorial Library, on Main Street, [ 1 ] which was designed by Alexander Longfellow , a nephew of the poet Henry Wadsworth Longfellow . [ 11 ]
Hammond served in the Maine Legislature between 1868 and 1870, was on the Maine Board of Agriculture and the board of trustees of North Yarmouth Academy , was a member of the American Association for the Advancement of Science , the Society of Chemical Industry , the American Institute of Mining, Metallurgical, and Petroleum Engineers , The Society of Arts and Crafts of Boston , the Massachusetts Historical Society , the New England Historic Genealogical Society (from January 1876), [ 12 ] The Bostonian Society and the Franklin Institute . He was also a Freemason . [ 4 ]
A member of the American Horticultural Society , he was a keen arborist , and his knowledge of trees and plants earned him a place on the Overseers' Committee at Harvard University 's Gray Herbarium between 1888 and the time of his death. [ 1 ] [ 4 ]
The Hammonds were members of Yarmouth's First Parish Congregational Church and Boston's Trinity Church . [ 4 ]
Hammond died on January 6, 1908, aged 74. He is interred in Mount Auburn Cemetery , Cambridge, Massachusetts . | https://en.wikipedia.org/wiki/George_W._Hammond |
George M. Weinstock (born February 6, 1949) is an American geneticist and microbiologist on the faculty of The Jackson Laboratory for Genomic Medicine, where he is a professor and the associate director for microbial genomics. Before joining The Jackson Laboratory, he taught at Washington University in St. Louis and served as associate director of The Genome Institute . Previously, Weinstock was co-director of the Human Genome Sequencing Center (HGSC) at Baylor College of Medicine in Houston, Texas, and Professor of Molecular and Human Genetics. He received his B.S. degree from the University of Michigan in 1970 and his Ph.D. from the Massachusetts Institute of Technology in 1977. He has spent most of his career taking genomic approaches to study fundamental biological processes.
Weinstock's parents met during the Manhattan Project in Los Alamos, New Mexico , and he grew up meeting many of the participants in the atomic bomb project and their colleagues. He performed his PhD thesis under David Botstein at MIT, studying the structure of phage P22 chromosome .
As a postdoctoral fellow with I. R. Lehman at Stanford University School of Medicine , Weinstock and Kevin McEntee discovered that the RecA protein of E. coli catalyzed strand transfer in genetic recombination . Later, as a faculty member at the University of Texas Health Science Center at Houston , he led one of the first bacterial genome projects, collaborating with The Institute for Genomic Research to sequence the entire genome of a bacterium, Treponema pallidum , the organism that causes syphilis . [ 2 ] In 1999 he joined Richard Gibbs at the HGSC as one of the five main centers to work on the Human Genome Project . [ 3 ] The HGSC produced sequences of human chromosomes 3, [ 4 ] 12 [ 5 ] and X. [ 6 ] Weinstock was a principal investigator in projects producing genome sequences for rat , [ 7 ] mouse , [ 8 ] macaque , [ 9 ] bovine , [ 10 ] sea urchin , [ 11 ] honey bee , [ 12 ] fruit fly [ 13 ] and many microbial genomes, as well as one of the first personal genome projects, sequencing James Watson ’s genome using next-generation sequencing technology. [ 14 ]
He was a leader of the Human Microbiome Project , [ 15 ] studying the collection of microbes that colonize the human body. [ 16 ] | https://en.wikipedia.org/wiki/George_Weinstock |
George Charles de Hevesy (born György Bischitz ; Hungarian : Hevesy György Károly ; German : Georg Karl von Hevesy ; 1 August 1885 – 5 July 1966) was a Hungarian radiochemist and Nobel Prize in Chemistry laureate, recognized in 1943 for his key role in the development of radioactive tracers to study chemical processes such as in the metabolism of animals. He also co-discovered the element hafnium . [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ] [ 6 ]
Hevesy György was born in Budapest , Hungary , to a wealthy and ennobled family of Hungarian-Jewish descent, [ 7 ] the fifth of eight children to his parents Lajos Bischitz and Baroness Eugénia (Jenny) Schossberger (ennobled as "De Tornya"). Grandparents from both sides of the family had provided the presidents of the Jewish community of Pest . [ 7 ] His parents converted to Roman Catholicism . [ 8 ] George grew up in Budapest and graduated high school in 1903 from Piarist Gimnázium . [ 9 ] The family's name in 1904 was Hevesy-Bischitz, and Hevesy later changed his own.
De Hevesy began his studies in chemistry at the University of Budapest for one year, and at the Technische Hochschule in Charlottenburg (now Technische Universität Berlin ) for several months, but transferred to the University of Freiburg . There he met Ludwig Gattermann . In 1906, he started his Ph.D. thesis with Georg Franz Julius Meyer, [ 10 ] acquiring his doctorate in physics in 1908. In 1908, Hevesy was offered a position at the ETH Zürich , Switzerland, yet being independently wealthy, he was able to choose his research environment. He worked first with Fritz Haber in Karlsruhe, Germany , then with Ernest Rutherford in Manchester, England , where he also met Niels Bohr . Back at home in Budapest , he was appointed professor in physical chemistry in 1918. In 1920, he settled in Copenhagen.
In 1922, de Hevesy co-discovered (with Dirk Coster ) the element hafnium ( 72 Hf) ( Latin Hafnia for " Copenhagen ", the home town of Niels Bohr ). Mendeleev 's 1869 periodic table arranged the chemical elements into a logical system, but a chemical element with 72 protons was missing. Hevesy determined to look for that element on the basis of Bohr's atomic model. The mineralogical museum of Norway and Greenland in Copenhagen furnished the material for the research. Characteristic X-ray spectra recordings made of the sample indicated that a new element was present. The accepted account has been disputed by Mansel Davies and Eric Scerri who attribute the prediction that element 72 would be a transition element to the chemist Charles Bury. [ citation needed ]
Supported financially by the Rockefeller Foundation , Hevesy had a very productive year. He developed the X-ray fluorescence analytical method, and discovered the samarium alpha-ray. It was here he began the use of radioactive isotopes in studying the metabolic processes of plants and animals, by tracing chemicals in the body by replacing part of stable isotopes with small quantities of the radioactive isotopes. In 1923, Hevesy published the first study on the use of the naturally radioactive 212 Pb as radioactive tracer to follow the absorption and translocation in the roots, stems and leaves of Vicia faba , also known as the broad bean. [ 11 ] [ 12 ] Later, in 1943, the work on radioactive tracing would earn Hevesy the Nobel Prize in Chemistry . [ 13 ]
In 1924, Hevesy returned to Freiburg as Professor of Physical Chemistry. In 1930, he went to Cornell University, Ithaca as Baker Lecturer. In 1934, after the Nazis came to power in Germany, he returned to Niels Bohr's Institute at the University of Copenhagen. In 1936, he invented Neutron Activation Analysis . In 1943 he fled to Stockholm (Sweden being neutral during the war), where he an associate of the Institute of Research in Organic Chemistry. In 1949 he was elected Franqui Professor in the University of Ghent . In his retirement, he remained an active scientific associate of the Stockholm University .
Prior to the onset of World War II, Max von Laue and James Franck had sent their gold Nobel Prize medals to Denmark to keep them from being confiscated by the Nazis. After the Nazi invasion of Denmark this placed them in danger; it was illegal at the time to send gold out of Germany, and were it discovered that Laue and Franck had done so, they could have faced prosecution. To prevent this, de Hevesy concealed the medals by dissolving them in aqua regia and placing the resulting solution on a shelf in his laboratory at the Niels Bohr Institute in Copenhagen. After the war, he returned to find the solution undisturbed and precipitated the gold out of the acid. The Nobel Society then recast the medals using the recovered gold and returned them to the two laureates. [ 14 ] [ 15 ]
By 1943, Copenhagen was no longer safe for a Jewish scientist and de Hevesy fled to Sweden, where he worked at the Stockholm University until 1961. In Stockholm, de Hevesy was received at the department of chemistry by the German-born Swedish professor and Nobel Prize winner Hans von Euler-Chelpin , who remained strongly pro-Germany throughout the war. Despite this, de Hevesy and von Euler-Chelpin collaborated on many scientific papers during and after the war.
While in Stockholm, de Hevesy received the Nobel Prize in chemistry. He was later inducted into the Royal Swedish Academy of Sciences and received the Copley Medal , of which he was particularly proud. De Hevesy stated: "The public thinks the Nobel Prize in chemistry for the highest honor that a scientist can receive, but it is not so. Forty or fifty have received Nobel chemistry prizes, but there are only ten foreign members of the Royal Swedish Academy, and only two have received a Copley." (Bohr was the other one.) He received the Atoms for Peace Award in 1958 for his peaceful use of radioactive isotopes .
De Hevesy married Pia Riis in 1924. They had one son and three daughters together, one of whom (Eugenie) married a grandson of the Swedish Nobel laureate Svante Arrhenius . [ 16 ] De Hevesy died in 1966 at the age of eighty and was buried in Freiburg. In 2000, his body was moved to the Kerepesi Cemetery in Budapest, Hungary. He had published a total of 397 scientific documents, one of which was the Becquerel-Curie Memorial Lecture, in which he had reminisced about the careers of pioneers of radiochemistry. [ 17 ] At his family's request, his ashes were interred at his birthplace in Budapest on 19 April 2001.
On 10 May 2005 the Hevesy Laboratory [ 18 ] was founded at Risø National Laboratory for Sustainable Energy , now Technical University of Denmark , DTU Nutech. It was named after George de Hevesy as the father of the isotope tracer principle under the initiative of the lab's first director, Prof. Mikael Jensen. | https://en.wikipedia.org/wiki/George_de_Hevesy |
Georges Pelletier (born 1943) is a French agricultural engineer and Doctor of Science . He spent his career at the National Institute of Agricultural Research (INRA) in the Department of Plant Genetics and Improvement. He headed the Unit of the INRA Versailles Centre from 1991 to 1999, chaired from 2001 to 2010, the Operational Management Board of the Group of Scientific Interest in Plant Genomics Genoplant, [ 1 ] and from 2010 to 2013 was appointed to the French Agency for Research (ANR) scientific manager of the Biotechnologies and Bio-resources programme for "Investments for the Future". He was a member of the Biomolecular Engineering Commission and the Scientific Council of the Genopoles. Member of the French Academy of sciences (2004) [ 2 ] and the Academy of Agriculture (2004), [ 3 ] he was awarded the Lauriers d'excellence de INRA (2006). [ 4 ]
His field of research has been the study of multiplication and reproduction mechanisms in angiosperms .
First, by generating haploid individuals, either by in vitro culture of immature pollen , in tobacco and asparagus , [ 5 ] or by selecting fertilization anomalies that eliminate one of the parental genomes . [ 6 ] This work has led to the clarification of sex determinism in asparagus, a dioecious species, and has provided the method for obtaining fully male F1 hybrid varieties , which have since been widely developed.
He developed a genetics of cytoplasmic organelles in higher plants by protoplast fusion, revealing the existence of almost systematic recombinations between mitochondrial genomes and the exchange of chloroplasts between the parents of these fusions. [ 7 ] The application of these principles to the species of the Brassicaceae family [ 8 ] has led to the discovery of the mitochondrial gene responsible for male sterility (absence of pollen) known as Ogura, which is found in the genus Raphanu s . [ 9 ] [ 10 ] It is an additional gene whose only biological function is to block pollen formation. It is involved in gynodoecia (a species composed of females and hermaphrodites ) in the genus Raphanus . The discovery of the gene responsible for male sterility, its transfer to Brassica by fusion of protoplasts, and the selection of mitochondrial recombinants with improved agronomic characteristics have enabled this male sterility to be widely distributed and exploited in Europe and North America for the production of hybrid varieties in rapeseed and various cabbage . [ 11 ]
He showed that the gene transfer bacterium, Agrobacterium tumefaciens , introduced by simple infiltration into the plant, is unexpectedly capable of transferring its T-DNA to female gametes . [ 12 ] [ 13 ] An original method of transformation to create collections of "insertion mutants" in the Arabidopsis thaliana genome has been developed for his team to study the genes that control reproductive mechanisms, whether they are meiosis and recombination of chromosomes [ 14 ] or gametogenesis , pollen and embryonic sac development. On a global scale, the method has been widely used as one of the major tools for functional analysis of the genome of A. thaliana , a plant model of plant genomics. | https://en.wikipedia.org/wiki/Georges_Pelletier_(agronomist) |
Georges Henri Reeb (12 November 1920 – 6 November 1993) was a French mathematician . He worked in differential topology , differential geometry , differential equations , topological dynamical systems theory and non-standard analysis .
Reeb was born in Saverne , Bas-Rhin , Alsace , to Theobald Reeb and Caroline Engel. He started studying mathematics at University of Strasbourg , but in 1939 the entire university was evacuated to Clermont-Ferrand due to the German occupation of France . [ 1 ]
After the war, he completed his studies and in 1948 he defended his PhD thesis, entitled Propriétés topologiques des variétés feuilletées [Topological properties of foliated manifolds] and supervised by Charles Ehresmann . [ 2 ]
In 1952 Reeb was appointed professor at Université Joseph Fourier in Grenoble and in 1954 he visited the Institute for Advanced Study . From 1963 he worked at Université Louis Pasteur in Strasbourg . [ 1 ] [ 3 ]
There, in 1965 he created with Jean Leray and Pierre Lelong the series of meeting Rencontres entre Mathématiciens et Physiciens Théoriciens . in 1966 Reeb and Jean Frenkel founded the Institute de Recherche mathématique Avancée , the first university laboratory associated to the Centre National de la Recherche Scientifique , which he directed between 1967 and 1972. [ 4 ]
In 1967 he was President of the Société Mathématique de France [ 5 ] and in 1971 he was awarded the Prize Petit d'Ormoy [ fr ] . [ 1 ] [ 3 ]
In 1991 Reeb received an honorary doctorate from Albert-Ludwigs-Universität Freiburg and from Université de Neuchâtel . He died in 1993 in Strasbourg when he was 72 years old. [ 1 ] [ 3 ]
Reeb was the founder of the topological theory of foliations , a geometric structure on smooth manifolds which partition them in smaller pieces. In particular, he described what is now called the Reeb foliation , a foliation of the 3-sphere , whose leaves are all diffeomorphic to R 2 {\displaystyle \mathbb {R} ^{2}} , except one, which is a 2- torus . [ 6 ]
One of its first significant result, Reeb stability theorem , describes the local structure foliations around a compact leaf with finite holonomy group .
His works on foliations had also applications in Morse theory . In particular, the Reeb sphere theorem says that a compact manifold with a function with exactly two critical points is homeomorphic to the sphere. In turn, in 1956 this was used to prove that the Milnor spheres , although not diffeomorphic, are homeomorphic to the sphere S 7 {\displaystyle S^{7}} . [ 7 ]
Other important geometric concepts named after him include the Reeb graph [ 8 ] and the Reeb vector field associated to a contact form .
Towards the end of his career, Reeb become a supporter of the theory of non-standard analysis by Abraham Robinson , coining the slogan "The naïve integers don't fill up N {\displaystyle \mathbb {N} } " [ 9 ] [ 10 ] and working on its applications to dynamical systems . [ 11 ] | https://en.wikipedia.org/wiki/Georges_Reeb |
The Georgia Safe Dams Program is part of the Environmental Protection Division of the Georgia Department of Natural Resources . [ 1 ] The Safe Dams Program must:
Category I dams might result in loss of human life upon failure or improper operation; Category II would not.
This article about a dam or floodgate in the United States is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Georgia_Safe_Dams_Program |
Geostandards and Geoanalytical Research is a quarterly peer-reviewed scientific journal covering reference materials , analytical techniques , and data quality relevant to the chemical analysis of geological and environmental samples . The journal was established in 1977 as Geostandards Newsletter and modified its title in 2004. The editors-in-chief are Thomas C. Meisel, Jacinta Enzweiler, Mary F. Horan, Kathryn L. Linge, Christophe R. Quétel and Paul J. Sylvester. It is published by Wiley-Blackwell on behalf of the International Association of Geoanalysts . The journal is a hybrid open-access journal, publishing both subscription and open access articles.
The journal publishes original research papers that include developments in analytical techniques, studies of geological-environmental reference materials, advances in statistical analysis of geoanalytical data, as well as data compilations, contributions to the characterisation of reference materials, as well as review articles and topical commentaries. It also publishes an annual bibliographic review article of the geoanalytical literature and a biennial series of critical reviews of analytical developments.
The journal is abstracted and indexed in:
According to the Journal Citation Reports , the journal has a 2018 impact factor of 4.256, ranking it 11th out of 84 journals in the category "Geochemistry and Geophysics". [ 2 ] | https://en.wikipedia.org/wiki/Geostandards_and_Geoanalytical_Research |
Geostationary Carbon Cycle Observatory ( GeoCarb ) [ 1 ] was an intended NASA Venture-class Earth observation mission that was designed to measure the carbon cycle .
GeoCarb was to be stationed over the Americas and make observations between 50° North and South latitudes. Its primary mission was to conduct observations of vegetation health and stress, as well as observe the processes that govern the carbon exchange of carbon dioxide , methane , and carbon monoxide between the land, atmosphere, and ocean. [ 2 ] [ 3 ] [ 4 ]
Selected by NASA in 2016. [ 5 ]
Originally intended to be mounted on a commercial geostationary communication satellite operated by SES S.A. , [ 6 ] a lack of hosting opportunities drove NASA, in Feb 2022, to seek a standalone spacecraft to carry GeoCarb. [ 5 ]
On 29 November 2022, NASA announced the cancellation of development of the GeoCarb mission, citing cost overruns and the availability of other options to measure and observe greenhouse gases, like the EMIT instrument on the ISS and the upcoming Earth System Observatory . [ 7 ]
GeoCarb was a joint collaboration between NASA's Ames Research Center , Goddard Space Flight Center , and Jet Propulsion Laboratory ; the University of Oklahoma ; Colorado State University ; the Lockheed Martin Advanced Technology Center of Palo Alto, California ; and SES Government Solutions (now SES Space & Defense ) of Reston, Florida . [ 4 ]
"The GeoCarb instrument consists of the aperture assembly, telescope, spectrometer, and electronics boxes. It is a four channel near-infrared, single-slit imaging spectrograph optimized to deduce concentrations of carbon dioxide, carbon monoxide and methane, and Solar-Induced Fluorescence (SIF) from Geostationary Orbit.
The instrument is built by Lockheed Martin Advanced Technology Center." [ 8 ] | https://en.wikipedia.org/wiki/Geostationary_Carbon_Cycle_Observatory |
In atmospheric science , geostrophic flow ( / ˌ dʒ iː ə ˈ s t r ɒ f ɪ k , ˌ dʒ iː oʊ -, - ˈ s t r oʊ -/ [ 1 ] [ 2 ] [ 3 ] ) is the theoretical wind that would result from an exact balance between the Coriolis force and the pressure gradient force. This condition is called geostrophic equilibrium or geostrophic balance (also known as geostrophy ). The geostrophic wind is directed parallel to isobars (lines of constant pressure at a given height). This balance seldom holds exactly in nature. The true wind almost always differs from the geostrophic wind due to other forces such as friction from the ground. Thus, the actual wind would equal the geostrophic wind only if there were no friction (e.g. above the atmospheric boundary layer ) and the isobars were perfectly straight. Despite this, much of the atmosphere outside the tropics is close to geostrophic flow much of the time and it is a valuable first approximation. Geostrophic flow in air or water is a zero-frequency inertial wave .
A useful heuristic is to imagine air starting from rest, experiencing a force directed from areas of high pressure toward areas of low pressure, called the pressure gradient force. If the air began to move in response to that force, however, the Coriolis force would deflect it, to the right of the motion in the northern hemisphere or to the left in the southern hemisphere . As the air accelerated, the deflection would increase until the Coriolis force's strength and direction balanced the pressure gradient force, a state called geostrophic balance. At this point, the flow is no longer moving from high to low pressure, but instead moves along isobars . Geostrophic balance helps to explain why, in the northern hemisphere, low-pressure systems (or cyclones ) spin counterclockwise and high-pressure systems (or anticyclones ) spin clockwise, and the opposite in the southern hemisphere.
Flow of ocean water is also largely geostrophic. Just as multiple weather balloons that measure pressure as a function of height in the atmosphere are used to map the atmospheric pressure field and infer the geostrophic wind, measurements of density as a function of depth in the ocean are used to infer geostrophic currents. Satellite altimeters are also used to measure sea surface height anomaly, which permits a calculation of the geostrophic current at the surface.
The effect of friction, between the air and the land, breaks the geostrophic balance. Friction slows the flow, lessening the effect of the Coriolis force. As a result, the pressure gradient force has a greater effect and the air still moves from high pressure to low pressure, though with great deflection. This explains why high-pressure system winds radiate out from the center of the system, while low-pressure systems have winds that spiral inwards.
The geostrophic wind neglects frictional effects, which is usually a good approximation for the synoptic scale instantaneous flow in the midlatitude mid- troposphere . [ 4 ] Although ageostrophic terms are relatively small, they are essential for the time evolution of the flow and in particular are necessary for the growth and decay of storms. Quasigeostrophic and semi geostrophic theory are used to model flows in the atmosphere more widely. These theories allow for a divergence to take place and for weather systems to then develop.
Newton's second law can be written as follows if only the pressure gradient, gravity, and friction act on an air parcel, where bold symbols are vectors:
Here U is the velocity field of the air, Ω is the angular velocity vector of the planet, ρ is the density of the air, P is the air pressure, F r is the friction, g is the acceleration vector due to gravity and D / D t is the material derivative .
Locally this can be expanded in Cartesian coordinates , with a positive u representing an eastward direction and a positive v representing a northward direction. Neglecting friction and vertical motion, as justified by the Taylor–Proudman theorem , we have:
With f = 2Ω sin φ the Coriolis parameter (approximately 10 −4 s −1 , varying with latitude).
Assuming geostrophic balance, the system is stationary and the first two equations become:
By substituting using the third equation above, we have:
with z the geopotential height of the constant pressure surface, satisfying
Further simplify those formulae above:
f v = − g c a = + g ( d z d x ) d y = 0 f u = + g c b = − g ( d z d y ) d x = 0 {\displaystyle {\begin{aligned}fv&={\frac {\;-g\;}{\;c\;}}a=+g{\biggl (}{\frac {{\rm {d}}z}{{\rm {d}}x}}{\biggr )}_{{\rm {d}}y=0}\\[5px]fu&=+{\frac {\;g\;}{\;c\;}}b=-g{\biggl (}{\frac {{\rm {d}}z}{{\rm {d}}y}}{\biggr )}_{{\rm {d}}x=0}\end{aligned}}}
This leads us to the following result for the geostrophic wind components:
v g = g f d z d x {\displaystyle v_{g}={g \over f}{{\rm {d}}z \over {\rm {d}}x}}
u g = − g f d z d y {\displaystyle u_{g}=-{g \over f}{{\rm {d}}z \over {\rm {d}}y}}
The validity of this approximation depends on the local Rossby number . It is invalid at the equator, because f is equal to zero there, and therefore generally not used in the tropics .
Other variants of the equation are possible; for example, the geostrophic wind vector can be expressed in terms of the gradient of the geopotential Φ on a surface of constant pressure: | https://en.wikipedia.org/wiki/Geostrophic_wind |
Geotagging , or GeoTagging , is the process of adding geographical identification metadata to various media such as a geotagged photograph or video, websites, SMS messages, QR Codes or RgSS feeds and is a form of geospatial metadata . This data usually consists of latitude and longitude coordinates , though they can also include altitude , bearing , distance, accuracy data, and place names, and perhaps a time stamp .
Geotagging can help users find a wide variety of location-specific information from a device. For instance, someone can find images taken near a given location by entering latitude and longitude coordinates into a suitable image search engine . Geotagging-enabled information services can also potentially be used to find location-based news, websites, or other resources. [ 1 ] Geotagging can tell users the location of the content of a given picture or other media or the point of view , and conversely on some media platforms show media relevant to a given location.
The geographical location data used in geotagging can, in almost every case, be derived from the global positioning system , and based on a latitude / longitude -coordinate system that presents each location on the earth from 180° west through 180° east along the Equator and 90° north through 90° south along the prime meridian . [ citation needed ]
The related term geocoding refers to the process of taking non-coordinate-based geographical identifiers, such as a street address, and finding associated geographic coordinates (or vice versa for reverse geocoding ). Such techniques can be used together with geotagging to provide alternative search techniques. [ citation needed ]
Geotagging is a popular feature on several social media platforms, such as Facebook and Instagram.
Facebook users can geotag photos that can be added to the page of the location they are tagging. Users may also use a feature that allows them to find nearby Facebook friends by generating a list of people according to the location tracker in their mobile devices. [ 2 ]
Instagram uses a map feature that allows users to geotag photos. The map layout pin points specific photos that the user has taken on a world map.
Two main options can be used to geotag photos: capturing GPS information at the time the photo is taken or "attaching" geocoordinates to the photograph after the picture is taken.
In order to capture GPS data at the time the photograph is captured, the user must have a camera with built in GPS or a standalone GPS along with a digital camera. Because of the requirement for wireless service providers in United States to supply more precise location information for 911 calls by September 11, 2012, [ 3 ] more and more cell phones have built-in GPS chips. Most smart phones already use a GPS chip along with built-in cameras to allow users to automatically geotag photos. Others may have the GPS chip and camera but do not have internal software needed to embed the GPS information within the picture. A few digital cameras also have built-on or built-in GPS that allow for automatic geotagging. [ 4 ]
Devices use GPS, A-GPS or both. A-GPS can be faster getting an initial fix if within range of a cell phone tower, and may work better inside buildings. Traditional GPS does not need cell phone towers and uses standard GPS signals outside of urban areas. Traditional GPS tends to use more battery power. Almost any digital camera can be coupled with a stand-alone GPS and post processed with photo mapping software, to write the location information to the image's exif header.
In the field of remote sensing the geotagging goal is to store coordinates of every pixel in the image. One approach is used with the orthophotos where we store coordinates of four corners and all the other pixels can be georeferenced by interpolation . The four corners are stored using GeoTIFF or World file standards. Hyperspectral images take a different approach defining a separate file of the same spatial dimensions as the image where latitude and longitude of each pixel are stored as two 2D layers in so called Input geometry data (IGM) files, [ 5 ] also known as GEO files.
Audio/video files can be geotagged via: metadata, audio encoding, overlay, or with companion files. Metadata records the geospatial data in the encoded video file to be decoded for later analysis. One of the standards used with unmanned aerial vehicle is MISB Standard 0601 which allows geocoding of corner points and horizon lines in individual video frames. [ 6 ] Audio encoding involves a process of converting gps data into audio data such as modem squawk. Overlay involves overlaying GPS data as text on the recorded video. Companion files are separate data files which correspond to respective audio/video files. Companion files are typically found in the .KML and .GPX data formats. [ 7 ] For audio and video files which use the vorbiscomment metadata format (including Opus , Ogg Vorbis , FLAC , Speex , and Ogg Theora ), there is a proposed GEO LOCATION [ 8 ] field which can be used. Like all vorbis comments, it is plain text, and it takes the form:
GEO_LOCATION=(decimal latitude);(decimal longitude);([optional]elevation in meters)
for example:
GEO_LOCATION=35.1592;-98.4422;410
The GeoSMS standard works by embedding one or more 'geo' URIs in the body of an SMS, for example:
RFC 1876 defines a means for expressing location information in the Domain Name System . LOC resources records can specify the latitude, longitude, altitude, precision of the location, and the physical size of on entity attached to an IP address. However, in practice not all IP addresses have such a record, so it is more common to use geolocation services to find the physical location of an IP address.
The GeoURL [ 9 ] method requires the ICBM tag [ 10 ] (plus optional Dublin Core metadata), which is used to geotag standard web pages in HTML format:
The similar Geotag format allows the addition of place name and region tags:
The RDF method is defined by W3 Group and presents the information in RDF tags: [ 11 ]
The Geo microformat allows coordinates within HyperText Markup Language pages to be marked up in such a way that they can be "discovered" by software tools. Example:
A proposal has been developed [ 12 ] to extend Geo to cover other bodies, such as Mars and the Moon .
An example is the Flickr photo-sharing Web site, which provides geographic data for any geotagged photo in all of the above-mentioned formats.
No industry standards exist, however there are a variety of techniques for adding geographical identification metadata to an information resource. One convention, established by the website Geobloggers and used by more and more sites, e.g. photo sharing sites Panoramio and Flickr , and the social bookmarking site del.icio.us , enables content to be found via a location search. Such sites allow users to add metadata to an information resource via a set of so-called machine tags (see folksonomy ).
This describes the geographic coordinates of a particular location in terms of latitude ( geo:lat ) and longitude ( geo:lon ). These are expressed in decimal degrees in the WGS84 datum , which has become something of a default geodetic datum with the advent of GPS . [ citation needed ]
Using three tags works within the constraint of having tags that can only be single 'words'. Identifying geotagged information resources on sites like Flickr and del.icio.us is done by searching for the 'geotagged' tag, since the tags beginning geo:lat= and geo:lon= are necessarily very variable.
Another option is to tag with a Geohash :
A further convention proposed by FlickrFly adds tags to specify the suggested viewing angle and range when the geotagged location is viewed in Google Earth :
These three tags would indicate that the camera is pointed heading 225° (south west), has a 45° tilt and is 560 metres from the subject.
Where the above methods are in use, their coordinates may differ from those specified by the photo's internal Exif data, for example because of a correction or a difference between the camera's location and the subject's.
In order to integrate geotags in social media and enhance text readability or oral use, the concept of 'meetag' or tag-to-meet has been proposed. Differing from hashtag construction, meetag includes the geolocation information after an underscore. A meetag is therefore a word or an unspaced phrase prefixed with an underscore ("_"). Words in messages on microblogging and social networking services may be tagged by putting "_" before them, either as they appear in a sentence, (e.g. "There is a concert going _montreuxjazzfestival", "the world wide web was invented _cern _geneve", ...) or appended to it. [ 13 ]
Geoblogging attaches specific geographic location information to blog entries via geotags . Searching a list of blogs and pictures tagged using geotag technology allows users to select areas of specific interest to them on interactive maps. [ 14 ]
The progression of GPS technology, along with the development of various online applications, has fueled the popularity of such tagged blogging, [ citation needed ] and the combination of GPS phones and GSM localization , has led to the moblogging , where blog posts are tagged with exact position of the user. Real-time geotagging relays automatically geotagged media such as photos or video to be published and shared immediately.
For better integration and readability of geotags into blog texts, the meetag syntax has been proposed, which transforms any word, sentence, or precise geolocalization coordinates prefixed with an underscore into a 'meetag'. It not only lets one express a precise location but also takes in account dynamically changing geolocations.
One of the first attempts to initiate the geotagging aspect of searching and locating articles seems to be the now-inoperative site Wikinear.com, launched in 2008, which showed the user Wikipedia pages that are geographically closest to one's current location. [ 15 ]
The 2009 app Cyclopedia works relatively well showing geotagged Wikipedia articles located within several miles of ones location, integrated with a street-view mode, and 360-degree mode.
The app Respotter Wiki, launched in 2009, claims to feature Wikipedia searching via a map, also allowing users to interact with people around them, via messaging and reviews, etc. The app, in its current function, however, seems to give only geotagged photo results.
As of 2017, the Wikipedia-World Project provides a simple map search tool which can display tagged articles near to a particular location, as well as a variety of more sophisticated tools integrated with external mapping services. [ 16 ]
Following a scientific study [ 17 ] and several demonstrative websites, [ 18 ] [ 19 ] a discussion on the privacy implications of geotagging has raised public attention. [ 20 ] [ 21 ] [ 22 ] [ 23 ] In particular, the automatic embedding of geotags in pictures taken with smartphones is often ignored by cell-phone users. As a result, people are often not aware that the photos they publish on the Internet have been geotagged. Many celebrities reportedly gave away their home location without knowing it. [ citation needed ] According to the study, a significant number of for-sale advertisements on Craigslist , that were otherwise anonymized, contained geotags, thereby revealing the location of high-valued goods—sometimes in combination with clear hints to the absence of the offerer at certain times. Publishing photos and other media tagged with exact geolocation on the Internet allows random people to track an individual's location and correlate it with other information. Therefore, criminals could find out when homes are empty because their inhabitants posted geotagged and timestamped information both about their home address and their vacation residence. These dangers can be avoided by removing geotags with a metadata removal tool for photos before publishing them on the Internet . [ citation needed ]
In 2007, four United States Army Apache helicopters were destroyed on the ground by Iraqi insurgent mortar fire; the insurgents had made use of embedded coordinates in web-published photographs (geotagging) taken of the helicopters by soldiers. [ 24 ]
Another newly realized danger of geotagging is the location information provided to criminal gangs and poachers on the whereabouts of often endangered animals. This can effectively make tourists scouts for these poachers, so geotagging should be turned off when photographing these animals.
According to Chinoitezvi Honour, some phones automatically geotag pictures hence location should be turned off when taking pictures. | https://en.wikipedia.org/wiki/Geotagging |
Geotechnical centrifuge modeling is a technique for testing physical scale models of geotechnical engineering systems such as natural and man-made slopes and earth retaining structures and building or bridge foundations. [ 1 ]
The scale model is typically constructed in the laboratory and then loaded onto the end of the centrifuge , which is typically between 0.2 and 10 metres (0.7 and 32.8 ft) in radius. The purpose of spinning the models on the centrifuge is to increase the g-forces on the model so that stresses in the model are equal to stresses in the prototype. For example, the stress beneath a 0.1-metre-deep (0.3 ft) layer of model soil spun at a centrifugal acceleration of 50 g produces stresses equivalent to those beneath a 5-metre-deep (16 ft) prototype layer of soil in earth's gravity .
The idea to use centrifugal acceleration to simulate increased gravitational acceleration was first proposed by Phillips (1869). [ 2 ] Pokrovsky and Fedorov (1936) [ 3 ] in the Soviet Union and Bucky (1931) [ 4 ] in the United States were the first to implement the idea. Andrew N. Schofield (e.g. Schofield 1980) [ 5 ] played a key role in modern development of centrifuge modeling.
A geotechnical centrifuge is used to test models of geotechnical problems such as the strength, stiffness and capacity of foundations for bridges and buildings, settlement of embankments, [ 6 ] stability of slopes, earth retaining structures, [ 7 ] tunnel stability and seawalls. Other applications include explosive cratering, [ 8 ] contaminant migration in ground water, frost heave and sea ice. The centrifuge may be useful for scale modeling of any large-scale nonlinear problem for which gravity is a primary driving force.
Geotechnical materials such as soil and rock have non-linear mechanical properties that depend on the effective confining stress and stress history. The centrifuge applies an increased "gravitational" acceleration to physical models in order to produce identical self-weight stresses in the model and prototype. The one to one scaling of stress enhances the similarity of geotechnical models and makes it possible to obtain accurate data to help solve complex problems such as earthquake -induced liquefaction, soil-structure interaction and underground transport of pollutants such as dense non-aqueous phase liquids. Centrifuge model testing provides data to improve our understanding of basic mechanisms of deformation and failure and provides benchmarks useful for verification of numerical models .
Note that in this article, the asterisk on any quantity represents the scale factor for that quantity. For example, in x ∗ = x m x p {\displaystyle x^{*}={\frac {x_{m}}{x_{p}}}} , the subscript m represents "model" and the subscript p represents "prototype" and x ∗ {\displaystyle x^{*}\,} represents the scale factor for the quantity x {\displaystyle x\,} . [ 9 ]
The reason for spinning a model on a centrifuge is to enable small scale models to feel the same effective stresses as a full-scale prototype. This goal can be stated mathematically as
where the asterisk represents the scaling factor for the quantity, σ m ′ {\displaystyle \sigma '_{m}} is the effective stress in the model and σ p ′ {\displaystyle \sigma '_{p}} is the effective stress in the prototype.
In soil mechanics the vertical effective stress, σ ′ {\displaystyle \sigma '} for example, is typically calculated by
where σ t {\displaystyle \sigma ^{t}} is the total stress and u {\displaystyle u} is the pore pressure. For a uniform layer with no pore pressure, the total vertical stress at a depth H {\displaystyle H} may be calculated by:
where ρ {\displaystyle \rho } represents the density of the layer and g {\displaystyle g} represents gravity. In the conventional form of centrifuge modeling, [ 9 ] it is typical that the same materials are used in the model and prototype; therefore the densities are the same in model and prototype, i.e.,
Furthermore, in conventional centrifuge modeling all lengths are scaled by the same factor L ∗ {\displaystyle L^{*}} . To produce the same stress in the model as in the prototype, we thus require ρ ∗ g ∗ H ∗ = ( 1 ) g ∗ L ∗ = 1 {\displaystyle \rho ^{*}g^{*}H^{*}=(1)g^{*}L^{*}=1\,} , which may be rewritten as
The above scaling law states that if lengths in the model are reduced by some factor, n, then gravitational accelerations must be increased by the same factor, n in order to preserve equal stresses in model and prototype.
For dynamic problems where gravity and accelerations are important, all accelerations must scale as gravity is scaled, i.e.
Since acceleration has units of L T 2 {\displaystyle {\frac {L}{T^{2}}}} , it is required that
Hence it is required that : 1 L ∗ = L ∗ T ∗ 2 {\displaystyle {\frac {1}{L^{*}}}={\frac {L^{*}}{T^{*2}}}} , or
Frequency has units of inverse of time, velocity has units of length per time, so for dynamic problems we also obtain
For model tests involving both dynamics and diffusion, the conflict in time scale factors may be resolved by scaling the permeability of the soil [ 9 ]
(this section obviously needs work!)
scale factors for energy, force, pressure, acceleration, velocity, etc.
Note that stress has units of pressure, or force per unit area. Thus we can show that
Substituting F = m∙a (Newton's law, force = mass ∙ acceleration) and r = m/L3 (from the definition of mass density).
Scale factors for many other quantities can be derived from the above relationships. The table below summarizes common scale factors for centrifuge testing.
Scale Factors for Centrifuge Model Tests (from Garnier et al., 2007 [ 9 ] )
(Table is suggested to be added here)
Large earthquakes are infrequent and unrepeatable but they can be devastating. All of these factors make it difficult to obtain the required data to study their effects by post earthquake field investigations. Instrumentation of full scale structures is expensive to maintain over the large periods of time that may elapse between major temblors, and the instrumentation may not be placed in the most scientifically useful locations. Even if engineers are lucky enough to obtain timely recordings of data from real failures, there is no guarantee that the instrumentation is providing repeatable data. In addition, scientifically educational failures from real earthquakes come at the expense of the safety of the public. Understandably, after a real earthquake, most of the interesting data is rapidly cleared away before engineers have an opportunity to adequately study the failure modes.
Centrifuge modeling is a valuable tool for studying the effects of ground shaking on critical structures without risking the safety of the public. The efficacy of alternative designs or seismic retrofitting techniques can compared in a repeatable scientific series of tests.
Centrifuge tests can also be used to obtain experimental data to verify a design procedure or a computer model. The rapid development of computational power over recent decades has revolutionized engineering analysis. Many computer models have been developed to predict the behavior of geotechnical structures during earthquakes and other loads. Before a computer model can be used with confidence, it must be proven to be valid based on evidence. The meager and unrepeatable data provided by natural earthquakes, for example, is usually insufficient for this purpose. Verification of the validity of assumptions made by a computational algorithm is especially important in the area of geotechnical engineering due to the complexity of soil behavior. Soils exhibit highly non-linear behavior, their strength and stiffness depend on their stress history and on the water pressure in the pore fluid, all of which may evolve during the loading caused by an earthquake. The computer models which are intended to simulate these phenomena are very complex and require extensive verification. Experimental data from centrifuge tests is useful for verifying assumptions made by a computational algorithm. If the results show the computer model to be inaccurate, the centrifuge test data provides insight into the physical processes which in turn stimulates the development of better computer models. | https://en.wikipedia.org/wiki/Geotechnical_centrifuge_modeling |
Geotextiles and Geomembranes is a bimonthly peer-reviewed scientific journal . It is the official journal of the International Geosynthetics Society and published on their behalf by Elsevier . The journal covers all topics relating to geosynthetics , including research, behaviour, performance analysis, testing, design, construction methods, case histories, and field experience.
The journal is abstracted and indexed in:
According to the Journal Citation Reports , the journal has a 2020 impact factor of 5.292. [ 4 ]
official web | https://en.wikipedia.org/wiki/Geotextiles_and_Geomembranes |
A geotope is the geological component of the abiotic matrix present in an ecotope . Example geotopes might be an exposed outcrop of rocks, an erratic boulder , a grotto or ravine, a cave, an old stone wall marking a property boundary, and so forth.
It is a loanword from German ( Geotop ) in the study of ecology and might be the model for many other similar words coined by analogy. As the prototype, it has enjoyed wider currency than many of the other words modelled on it, including physiotope , with which it is used synonymously. But the geotope is properly the rocks and not the whole lay of the land (which would be the physiotope).
For usage in the context of geoheritage , like e.g. in Friedrich Wiedenbein's contributions (see below) and in the German discussion on geoheritage, the more adequate term (and translation from the German) is geosite .
This ecoregion article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Geotope |
GEOTRACES is an international research programme for improving understanding of marine biogeochemical cycles .
GEOTRACES is organised internationally under the auspices of the Scientific Committee on Oceanic Research (originally under the International Council for Science ). Its management is overseen by a Scientific Steering Committee (SSC) , with representatives of 15 nations from across the globe, and the programme involves active participation of more than 30 nations.
The concept of cycle describes the pathway by which a chemical element moves through the three major compartments of Earth (such as continents, atmosphere, and ocean). Because these cycles are directly related to climate dynamics and are heavily impacted by global change, it is essential to quantify them. [ 1 ] [ 2 ] [ 3 ]
GEOTRACES focuses on the oceanic part of the cycles, with the ambition to map the distribution of trace elements and isotopes in the ocean and to understand the processes controlling this distribution. Some of these trace elements are directly linked to climate via, for example, their role as essential nutrients for life; others allow quantification of ocean processes (origin and dynamics of matter, age of water masses, etc.); some of them are pollutants (for example, lead or mercury). Modelling based on the data collected will thus achieve substantial progress in understanding the current and past of the ocean and improve projections of the ocean’s response to global change.
After some years in the planning and enabling phase, the GEOTRACES Science Plan was published in 2006 and the GEOTRACES programme formally launched its seagoing effort in January 2010. This phase is expected to last a decade.
Trace elements serve as regulators of biological processes in the ocean, influencing marine ecosystem dynamics and the carbon cycle . Despite this significance, knowledge of the marine biogeochemical cycles of these essential micronutrients is surprisingly incomplete. GEOTRACES is quantifying the supply, removal, internal cycling, chemical form and distribution of essential micronutrients and other trace elements. Understanding the sensitivity of these biogeochemical cycles to changing environmental conditions will improve projections of the ocean’s response to global change.
The cycles of many trace elements and isotopes have been impacted significantly by human activity, which has increased the discharge of harmful elements into the ocean. GEOTRACES’ emphasis on understanding the processes regulating the marine biogeochemical cycles of trace elements will improve prediction of the transport and fate of contaminants in the ocean and thereby help to protect the ocean environment.
Much of what is known about ocean conditions in the past and, therefore, about the ocean’s role in climate variability is derived from trace element and isotope patterns recorded in marine archives (sediments, corals, etc.). Greater knowledge of the processes governing these tracers in the modern ocean will improve interpretation of ocean conditions in the past, from which more reliable prediction of future changes can be made.
Benefits will be realised by pursuing two overarching goals:
The central component of GEOTRACES is a series of cruises spanning the global ocean and sampling the full water column. These dedicated GEOTRACES cruises collect seawater for analysis of a wide range of trace element and isotopes. This strategy is guided by the principle that more will be learned through complementary investigation of multiple trace elements than can be achieved in an exhaustive study of one element in isolation.
The first GEOTRACES cruise was cruise GPc06 in August 2005 in the North Pacific, though the program was officially launched in January/February 2010. [ 4 ] [ 5 ] The first U.S. GEOTRACES cruise was in fall 2010 on the R/V Knorr in the North Atlantic. [ 6 ]
Ensuring accuracy of the results is essential if GEOTRACES is to build a meaningful global dataset. To this end, the [1] Standards and Intercalibration (S&I) Committee is in charge of securing that truthful and precise data are generated in the GEOTRACES Program through the use of appropriate sampling protocols, analytical standards and certified reference materials, and the active sharing of methods and results.
Since the concentration, activity, or chemical speciation of a trace element or isotope can be affected by sampling methods, sample handling, and analytical determinations, GEOTRACES follows the strategy of cruises to occupy a common station along their transects. At the same time two U.S.-led cruises (2008 and 2009) provided samples for intercalibration to laboratories from many countries. Seawater samples are available for use by other labs that wish to join this effort.
Simple data comparisons like depth profiles show whether there are disagreements and, if so, the investigators can examine their methods and even data work ups to identify and remedy the problems.
Compilation of data into secure and readily searchable databases ensures ease of use and is fundamental to the success of the programme. The GEOTRACES Data Assembly Centre (GDAC) is responsible for the compilation, quality control and secure archiving of data received from national data centers and from core international GEOTRACES cruises. It has as its main aims the integration of core GEOTRACES data into global data sets, and making this data accessible to participating scientist and the larger science community according to the GEOTRACES data policy. The GDAC is hosted at the British Oceanographic Data Centre and a dedicated committee with international representation oversees it.
GEOTRACES Data Products are freely available on-line . The third Intermediate Data Product (IDP2021) was released in November 2021. It contains hydrographical and marine geochemical data acquired during the first 10 years of the programme. The main motivation for distributing the product at this time is to strengthen and intensify collaboration with the broader ocean research community. At the same time, GEOTRACES is seeking feedback to improve future data products.
The GEOTRACES Intermediate Data Product [ 7 ] [ 8 ] [ 9 ] consists of two parts: the digital data package and the eGEOTRACES Electronic Atlas .
The digital data package (available at http://www.bodc.ac.uk/geotraces/data/dp ) contains data from 77 cruises and more than 800 hydrographic and geochemical parameters. The data covers the global ocean, data density being the highest in the Atlantic.
The eGEOTRACES Electronic Atlas (available at www.egeotraces.org ) is based on the digital data package and provides 2D and 3D images of the ocean distribution of many of the parameters. The 3D figures provide geographical context crucial for correctly assessing extent and origin of tracer plumes as well as for inferring processes acting on the tracers and shaping their distribution. The numerous links to other tracers, sections and basins found on section plots and 3D animations allow quick switching between parameters and domains and facilitate comparative studies. In addition, eGEOTRACES can help in teaching and outreach activities and can also facilitate conveying societally relevant scientific results to interested laymen or decision makers.
The GEOTRACES SSC was initially led by co-chairs, Prof. Robert F. Anderson of the Lamont–Doherty Earth Observatory (Columbia University) and Prof. Gideon M. Henderson from University of Oxford . Eventually, the co-chairs transitioned to Dr. Maeve Lohan of the University of Southampton and Dr. Karen Casciotti from Stanford University . [ when? ]
In 2018, the SSC chairs were occupied by Phoebe Lam ( University of California, Santa Cruz ) and Andy Bowie ( University of Tasmania ). [ 10 ] | https://en.wikipedia.org/wiki/Geotraces |
Gerald Amery Wingrove MBE (1934 - 2019) was a model engineer and author from the United Kingdom. [ 1 ] He is best known as a modeller of cars.
Wingrove left his job as a lathe operator to create models full-time in November 1967, and launched himself as a freelance model engineer , [ 2 ] since which time he has hand crafted in metal almost 280 automobile miniatures in the scales of 1/20 & 1/15th, primarily in 1/15th scale. Most of these were commissioned by the vehicles' owners.
The first sale of his work by a major London Auction House was by Christie's on 2 August 1967 with the sale of 2 models of sailing ships in 96th scale and a SE5A aircraft model (1/20th scale) in brass and silk.
Further sales of his work were with Brooks (later amalgamated with Bonhams ) of London, 21 Lots, in (Sale 112) on 4 December 1999 – and Bonhams (Sale 1793) with 74 Lots on 1 December 2003, in London.
In July 2000, Wingrove was made a Member of the Order of the British Empire for craftsmanship, and "services to Model Engineering"
In March 2005 Wingrove was awarded ‘Metalworking Craftsman of the Year’, by The Joe Martin Foundation for Exceptional Craftsmanship in the USA. [ 3 ]
As well as cars, Wingrove has also created ship models and dioramas, the largest being the 25 square feet model of the village and ship yard of Bucklers Hard , commissioned for the Bucklers Hard Maritime Museum. [ citation needed ]
This article about a writer or poet from the United Kingdom is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Gerald_Wingrove |
Geranylfarnesyl pyrophosphate is an intermediate used by organisms in the biosynthesis of sester terpenoids . [ 1 ]
This biochemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Geranylfarnesyl_pyrophosphate |
Geranylgeranylation is a form of prenylation , which is a post-translational modification of proteins that involves the attachment of one or two 20-carbon lipophilic geranylgeranyl isoprenoid units from geranylgeranyl diphosphate to one or two cysteine residue(s) at the C-terminus of specific proteins. Prenylation (including geranylgeranylation) is thought to function, at least in part, as a membrane anchor for proteins. [ 1 ]
The process of geranylgeranylation can be catalyzed by either geranylgeranyl transferase I (GGTase I) or Rab GGTase (also GGTase II). GGTase I catalyzes the addition of one geranylgeranyl group onto the C-terminal consensus sequence CAAL (somewhat similar to farnesyltransferase reactions), where C=cysteine, A=any aliphatic amino acid, and L=leucine. Rab GGTase adds a total of two geranylgeranyl groups onto two cysteine residues at the C-terminal consensus sequence CXC or XXCC. The source of the geranylgeranyl group is geranylgeranyl diphosphate, which is synthesized by GGPS1 within the isoprenoid biosynthetic pathway. [ 2 ]
An example of this can be seen in the lipid anchoring of the Rho GTPase family of signaling molecules and the gamma subunit of heterotrimeric G proteins . | https://en.wikipedia.org/wiki/Geranylgeranylation |
Gerard Joseph Foschini (February 28, 1940 - September 17, 2023), was an American telecommunications engineer who worked for Bell Laboratories from 1961 until his retirement. He died in September 2023. His research has covered many kinds of data communications, particularly wireless communications and optical communications . Foschini has also worked on point-to-point systems and networks .
Foschini received the B.S.E.E. degree from the New Jersey Institute of Technology , the M.E.E. degree from New York University and a Ph.D. (1967) from the Stevens Institute of Technology . [ 1 ] In December 1962, he joined AT&T Bell Laboratories, where he has worked since. He has also taught at Princeton University and Rutgers University .
Within the telecommunications engineering field, he is best known for his invention of Bell Laboratories Layered Space-Time (BLAST). One of the first developments in MIMO (multiple input, multiple output) wireless technology. [ 2 ] [ 3 ] [ 4 ] This is a scheme for use in wireless communications which recommends the use of multiple antennas at both the transmitter and receiver. By careful allocation of the data to be transmitted to the transmitting antennas, multiple data streams can be transmitted simultaneously within a single frequency band — the data capacity of the system then grows directly in line with the number of antennas. This represents a significant advance on single-antenna systems.
Foschini's 1996 paper, not published until 1998, "On limits of wireless communications in a fading environment when using multiple antennas" , [1] played a key role advancing multiple-input multiple-output wireless systems. Shortly after that publication, in a technical memorandum for his employers, [2] Foschini introduced the BLAST concept, which is one of the most widely examined techniques in wireless communications research today. Among his later contributions, the paper offering a simplified form of the original BLAST architecture, called Vertical BLAST (V-BLAST), [3] has also resulted in intensive international research efforts. In 2002, Bell Laboratories' patent on BLAST was named by MIT 's Technology Review Magazine as one of five "Patents to watch". According to the Institute for Scientific Information Foschini is in the top 0.3% of most-cited authors. His papers have been cited over 50,000 times, resulting in an H-index of 63 and an i10-index of 114. [ 5 ]
In 2002, Foschini received the Thomas Alva Edison Patent Award , an honor given to people from New Jersey who have changed the world with their inventions; he has also received the Bell Labs Inventor's Award, Gold Award and Teamwork Award and holds the titles of "Distinguished Member of Staff, Distinguished Inventor" in the Laboratories. [ 6 ] Before his work on BLAST, Foschini had already been elected a fellow of the Institute of Electrical and Electronics Engineers in 1986, "for contributions to communications theory". [ 7 ] [ 8 ]
Foschini received the 2008 IEEE Alexander Graham Bell Medal "For seminal contributions to the science and technology of multiple-antenna wireless communications." And the IEEE Eric E. Sumner Award in 2006. Also in 2008 he received the New Jersey Institute of Technology Alumni Achievement Honor Roll Award and the IEEE Communication Theory Committee Technical Achievement Award. On March 28, 2015, he received the Stevens Technology Distinguished Alumni Award for Engineering, [ 9 ] [ 10 ] and is part of the Stevens Institute of Technology top 150 in 150 years.
In 2018, Foschini was honored as an NJIT magazine Top Influencer from the Institution. [ 11 ]
In 2009, Foschini was elected to the National Academy of Engineering. [ 12 ]
On September 17, 2023 Foschini died after suffering from Parkinson's disease for several years. | https://en.wikipedia.org/wiki/Gerard_J._Foschini |
Gerardus Johannes Maria Meijer (born 1962 in Zeddam ), more often Gerard J. M. Meijer is a Dutch physicist who has made significant contributions in the field of molecular physics , with a particular focus on laser-based spectroscopic detection techniques and cold molecules. [ 1 ] His group invented the technique of Stark deceleration using the Stark effect for controlled generation of cold molecules. [ 2 ]
Meijer was born in Zeddam and attended high school in Doetinchem . He studied physics at Radboud University in Nijmegen from 1980, receiving his diploma in 1985 and his Ph.D. in Physics from the same university in 1988 under the supervision of Antoni Dymanus and Peter Andresen. [ 3 ] After completing his Ph.D., Meijer spent a year as a post-doc at the IBM Research Center in San Jose, California , where he worked in the group of Mattanjah de Vries [ 1 ] on laser desorption mass spectrometry and optical spectroscopy, as well as fullerene. He then returned to Radboud University as a University Lecturer, where he continued his research on cavity ring-down spectroscopy and fullerene crystals.
In 1995, Meijer was appointed as a Full Professor in Experimental Physics at Radboud University, where he continued his research on laser-based spectroscopic techniques and cold molecules. He also became involved in molecular physics studies with IR-FEL (FELIX) radiation.
In 2000, Meijer was appointed as the Director of the FOM Institute for Plasma Physics "Rijnhuizen" in Nieuwegein , The Netherlands, where he continued his research on cold molecules and molecular physics studies with FELIX. In 2002, he was appointed as the Director of the Fritz Haber Institute of the Max Planck Society in Berlin, Germany, where he continued his research on gas-phase molecular physics, cold molecules, clusters, and biomolecules. In 2012, Meijer became an External Scientific Member of the Fritz Haber Institute and also took on the role of President of the Executive Board at Radboud University. [ 4 ] Since 2017, he returned to the directorship of the Fritz Haber Institute. [ 5 ]
Throughout his career, Meijer has received numerous awards and accolades for his contributions to the field of molecular physics, including the van't Hoff Prize from the German Bunsen Society in 2012 and the Bourke Award from the Royal Society of Chemistry in 2009. He has also was elected as a corresponding member of the Royal Netherlands Academy of Arts and Sciences in 2004 and member of the Academia Europaea in 2013. [ 6 ] [ 7 ] | https://en.wikipedia.org/wiki/Gerard_Meijer |
The Gerard P. Kuiper Prize is awarded annually by the Division for Planetary Sciences of the American Astronomical Society for outstanding lifetime achievement in the field of planetary science . The prize is named for Gerard P. Kuiper . [ 1 ]
Source: Gerard P. Kuiper Prize, American Astronomical Society | https://en.wikipedia.org/wiki/Gerard_P._Kuiper_Prize |
The Gerber method is a primary and historic chemical test to determine the fat content of substances, most commonly milk and cream. [ 1 ] The Gerber method is the primary testing method in Europe and much of the world. [ 2 ] The fairly similar Babcock test is used primarily in the United States , although the Gerber method also enjoys significant use in the U.S. as well. [ 3 ]
The Gerber method was developed and patented by Dr. Niklaus Gerber of Switzerland in 1891. [ 4 ]
Milk fat is separated from proteins by adding sulfuric acid . The separation is facilitated by using amyl alcohol and centrifugation. The fat content is read directly via a special calibrated butyrometer. Gerber developed specialized butyrometers (tubes), pipettes , and centrifuges . Water baths built specifically for the Gerber tubes are often used.
The test is still in widespread use today and is the basis for numerous national and international standards such as ISO 2446, International Dairy Federation (FIL) Regulation 105, BS 696 (United Kingdom), and IS 1223 (India). Larger facilities may prefer to use faster analysis techniques such as infrared spectroscopy as these greatly reduce the potential for user error and reduce the time and COSHH requirements.
The test continues to be improved and standardized. [ 5 ]
The two major defects associated with the Gerber method include: | https://en.wikipedia.org/wiki/Gerber_method |
Gerel Ochir ( Mongolian : Гэрэл Очир ; born 17 July 1941) is a Mongolian geologist. She specializes in petrology , geochemistry , and metallogeny . She has taught at the Mongolian University of Science and Technology for over 50 years and headed the Department of Geology for 30 years.
After earning bachelor's and master's degrees in geology, geochemistry, and petrology from Charles University in Prague, she received her PhD and ScD through the Siberian Branch of the Russian Academy of Sciences .
Ochir has served as vice president of the International Union of Geological Sciences and received the Jan Masaryk Medal in 2021.
Gerel Ochir was born in Moscow on 17 July 1941. She gained an interest in geology at the age of 10 after her mother gave her a book on geology by Russian geochemist Alexander Fersman . She graduated from secondary school in Ulaanbaatar in 1958. [ 1 ]
From 1959, Ochir attended Charles University in Prague. She earned a bachelor's degree in geology and petrography in 1964. She then spent a year with the Department of Geological Survey at the Central Geological Laboratory before she started teaching at the Mongolian State University (now Mongolian University of Science and Technology ) in 1965. [ 1 ] She later returned to Charles University, earning her RNDr. in geology and geochemistry in 1980. [ 2 ] Ochir earned her PhD in petrology from the Irkutsk Institute of Geochemistry of the Siberian Branch of the Russian Academy of Sciences in 1978. Her thesis was on the "Petrology and geochemistry of granite with crystal-bearing pegmatites of Eastern Mongolia." [ 1 ] Ochir earned her ScD in geochemistry, petrology, and metallogeny from the Vinogradov Institute of Geochemistry of the Russian Academy of Sciences in 1990. [ 1 ]
Ochir has been a professor at the Mongolian University of Science and Technology since 1965. She held the positions of assistant professor, associate professor and professor, teaching courses in petrology and petrography. She served as the head of the university's Department of Geology and Mineralogy from 1978 to 2009. She has also served as Director of the university's Geoscience Center since 2001. [ 3 ]
Ochir has carried out field and basic research work through joint expeditions of the Russian and Mongolian Academies of Sciences. [ 1 ] She is the author of over 350 scientific publications and was the lead editor of the book Mineral Resources of Mongolia . [ 4 ]
Ochir served as vice president of the International Union of Geological Sciences for four years. [ 5 ] She is an adjunct professor at the Institute of Mineral Resources of the Chinese Academy of Geological Sciences and a foreign member of the Russian Academy of Natural Sciences . [ 1 ]
Ochir is an Honoured Scientist of Mongolia. She was presented with the Jan Masaryk Medal by the Czech Ambassador in 2021. [ 6 ]
Ochir married a chemist and has one daughter. [ 1 ] | https://en.wikipedia.org/wiki/Gerel_Ochir |
The Gerhard Herzberg Canada Gold Medal for Science and Engineering is awarded by the Natural Sciences and Engineering Research Council (NSERC) of Canada to recognize "research contributions characterized by both excellence and influence." [ 1 ] Prior to 2000, NSERC had awarded the Canada Gold Medal for Science and Engineering , before deciding to rename the award to honour Gerhard Herzberg , winner of the 1971 Nobel Prize in Chemistry . [ 2 ]
The Herzberg medal is commonly called Canada's top award for science and engineering. [ 2 ] [ 3 ] [ 4 ] It is an individual annual award that recognizes continued excellence and influence in research in either natural sciences or engineering. [ 5 ] The award is a gold medal, and the guarantee of $1 million over five years to use for personal research. [ 5 ]
NSERC's Canada Gold Medal for Science and Engineering was first awarded in 1991 to Raymond Lemieux , a chemist working at University of Alberta . [ 6 ] Mathematician James Arthur from the University of Toronto was the 1999 recipient, [ 7 ] the last year before the award was renamed in honour of Gerhard Herzberg , the winner of the 1971 Nobel Prize in Chemistry . [ 2 ] NSERC decided to rename the award after Herzberg because they felt he embodied the two main qualities of the award, namely research contributions that are of high quality and influential. [ 5 ]
The Herzberg medal is awarded to a scientist or engineer working at a facility in Canada. It is considered Canada's top award for science and engineering. [ 2 ] [ 3 ] [ 4 ] Eligible facilities include universities, government and private labs. Nominations can be submitted by any Canadian citizen or permanent resident. The winner is chosen by a selection committee representing different scientific disciplines, who make a recommendations to the current NSERC president. [ 8 ] The award consists of a gold medal, and the guarantee of at least $1 million to use for research or for establishing research chairs, fellowships or scholarships in the recipients' name. [ 5 ]
From 2002 until 2009, three finalists were selected for the Herzberg Medal, and the winner selected from among them. The other two finalists (if it was their first time as a finalist) were awarded NSERC's Award of Excellence. [ 12 ]
Canadian Association of Physicists#CAP Herzberg Medal | https://en.wikipedia.org/wiki/Gerhard_Herzberg_Canada_Gold_Medal_for_Science_and_Engineering |
Gerhard Paul Hochschild (April 29, 1915 in Berlin – July 8, 2010 in El Cerrito, California ) was a German-born American mathematician who worked on Lie groups , algebraic groups , homological algebra and algebraic number theory .
On April 29, 1915, Hochschild was born to a middle-class Jewish family in Berlin , Germany, [ 1 ] [ 2 ] the son of Lilli and Heinrich Hochschild. [ 3 ] Hochschild had an older brother. [ 1 ] His father was a patent attorney who had an engineering degree. After the rise of the National Socialist German Workers' Party in 1933, his father sent him to South Africa where he was able to enroll in school with funding from the Hochschild Family Foundation established by Berthold Hochschild , a cousin of his grandfather. [ 4 ]
In 1936, Hochschild earned a BS degree in mathematics from University of Cape Town in Union of South Africa. [ 1 ] In 1937, Hochschild earned a MS degree in mathematics from University of Cape Town . [ 1 ] In 1941, Hochschild earned his PhD in mathematics from Princeton University . [ 1 ] Hochschild completed his thesis in 1941 at Princeton University with Claude Chevalley on Semisimple Algebras and Generalized Derivations .
In 1956–7 Hochschild was at the Institute for Advanced Study . Hochschild was a professor at University of Illinois at Urbana-Champaign . In the late 1950s Hochschild was a professor at University of California, Berkeley .
Hochschild (1945) introduced Hochschild cohomology , a cohomology theory for algebras, which classifies deformations of algebras. Hochschild & Nakayama (1952) introduced cohomology into class field theory . Along with Bertram Kostant and Alex F. T. W. Rosenberg , the Hochschild–Kostant–Rosenberg theorem is named after him. [ 5 ]
Among his students were Andrzej Białynicki-Birula and James Ax .
In 1955, Hochschild was a Guggenheim Fellow . In 1979 Hochschild was elected to the National Academy of Sciences , and in 1980 he was awarded the Leroy P. Steele Prize of the AMS .
In 1982, Hochschild retired but continued teaching part-time until 1985. [ 1 ]
In July 1950, Hochschild married Ruth Heinsheimer. [ 6 ] Ruth was born in Germany and fled with her mother in 1939; the couple met at the University of Illinois where she was earning her M.S. in mathematics and Gerhard was working as an assistant professor. [ 7 ] Hochschild's children are Ann Hochschild (b. 1955) and Peter Hochschild (b. 1957). [ 1 ] [ 8 ]
On July 8, 2010, Hochschild died at his home. Hochschild was 95. [ 1 ] | https://en.wikipedia.org/wiki/Gerhard_Hochschild |
Gerhard Lagaly (born 14 October 1938, in Ludwigshafen am Rhein ) is a German chemist and retired university professor.
In 1957, Lagaly started his chemistry studies (as well as Physics, Mineralogy and Botany) at the Heidelberg University , receiving his degree as " Diplom-Chemiker " in 1962. He conducted his doctorate studies at the Institute for Inorganic Chemistry at the same institution under Armin Weiss , and was awarded his Doctor degree in 1967 with the work " Untersuchung von Quellungsvorgängen in n-Alkylammonium-Schichtsilicaten ". From 1965 he worked as an Assistant at the Institute for Inorganic Chemistry of the Munich University where he concluded his Habilitation in 1971 and then was employed as lecturer (" Akademischer Rat/Oberrat "). In 1974 he was employed as Professor for Inorganic Chemistry at the University of Kiel , retiring in 2004.
His research lines concentrated on Clay chemistry , Colloid chemistry and Interface chemistry as well as chemistry from porous compounds, layered materials and intercalation chemistry .
Among his many contributions to the fields of clay and colloid chemistry , one of his most recognized developments was the Alkylammonium Method for the determination of layer charge in layered aluminosilicates. [ 1 ]
He acted as treasurer of the German Colloid Society from 1979 to 2003. [ 2 ] In 2004 the same institution awarded him with the Wolfgang Ostwald Prize. [ 3 ] Lagaly was President of the German Clay Group (DTTG) from 1987 to 1992 and of the European Clay Groups Association (ECGA) from 1999 to 2003.
In addition, Lagaly acted for many years (1987-2004) as editor-in-chief for "Colloid and Polymer Science" [ 4 ] and "Progress Colloid and Polymer Science" [ 5 ] as well as editor for "Clay Minerals" [ 6 ] (1982-1996) and "Applied Clay Science" [ 7 ] (1985-1996).
The German Clay Group (DTTG) [ 15 ] awards the Gerhard Lagaly Award, to " internationally excellent scientists with outstanding original research in the field of clay mineralogy. " The award is designated after the internationally highly recognized clay scientist and the distinguished member of the DTTG, Professor Dr. Dr. Gerhard Lagaly. [ 16 ]
The prize was first awarded in 2014 to Prof. Dr. Juraj Bujdák (Comenius University Bratislava). In 2016, the prize went to Dr. habil. Sabine Petit (Université de Poitiers). The recipient of the 2018 prize was Dr. Stephan Kaufhold (BGR Hannover). [ 17 ]
In March 2017 a hydrated calcium phyllomanganate with formula Ca 2x Mn 1−x O 2 •1.5-2H 2 O (x = 0.05–0.08) was accepted as new mineral by the International Mineralogical Association . This new species was discovered and described by Dr. Thomas Witzke and colleagues. It was named Lagalyite , in honor of Gerhad Lagaly and his contributions to the fields of clay chemistry and mineralogy. [ 18 ] [ 19 ] | https://en.wikipedia.org/wiki/Gerhard_Lagaly |
Gerhard Martin Julius Schmidt ( Hebrew : גרהרד מרטין יוליוס שמידט ; 21 August 1919 in Berlin – 12 July 1971, in Zurich, buried in Rehovot), was an organic chemist and chemical crystallographer , dean of the chemistry faculty of the Weizmann Institute of Science , and its scientific director in 1969. Schmidt was the founder of X-ray crystallography at the Weizmann Institute and in Israel – a field in which Weizmann Institute's Professor Ada Yonath was awarded the Nobel Prize in Chemistry for 2009.
Schmidt was born in Berlin in 1919 and went to high school in Munich , where his father was a professor of chemistry. Being the son of a Jewish mother, Gerhard was forced to leave Germany at the age of 16, after the Nazis came to power; he spent a year in Switzerland , then moved to England , where he finished high school in 1938. He then won a scholarship to study at the University of Oxford (Oriel College). He earned a master's degree in organic chemistry in 1942 under the guidance of Robert Robinson , and a doctorate in X-ray crystallography under Dorothy Hodgkin in 1948. Both of his supervisors were later awarded Nobel Prizes in chemistry.
During his doctoral studies, Schmidt took part in structural studies of biologically important molecules, focusing on the structure of the antibacterial natural peptide Gramicidin S using the method of X-ray crystallography. During this period he supervised another student of Hodgkin, Margaret Roberts, later Margaret Thatcher .
After the breakout of World War II , Schmidt was forced to interrupt his studies. Being an emigrant from Germany, he was deported in July 1940, together with 200 other “enemy aliens,” to a detention camp in Australia . In August 1941, he was finally cleared and returned to England. Later in life, Schmidt liked to date some of his most original ideas in chemistry to this deportation period.
Schmidt arrived in Israel and joined the soon-to-be-dedicated Weizmann Institute in late 1948. He had been invited by Ernst Bergmann , then the Institute's scientific director, to set up a research group in chemical crystallography. He later gradually broadened his activities to include solid-state chemistry and crystal spectroscopy.
At the Weizmann Institute, Schmidt combined scientific research with holding senior administrative positions. From 1959 to 1961, he served as chairman of the Institute's Scientific Committee and its administrative director. He was appointed head of the Department of Chemistry in 1967 and, with the establishment of the chemistry faculty in 1970, became its first dean. In 1969 he served as the Scientific Director of the Weizmann Institute. In 1970 this position was absorbed into the President position, and Schmidt became a Dean of the Chemistry Faculty. [ 1 ]
In the late 1950s, while serving as Weizmann's Administrative Director, Schmidt was among the pioneers of the German-Israeli scientific collaboration, which began with ties between the Weizmann Institute and the Max Planck Society . This initiative led to the creation of the Minerva Stiftung [ de ] in 1964 and paved the way for the establishment of formal relations between Israel and Germany in 1965.
Schmidt devoted considerable time to applied science. From 1960 to 1964, he chaired the Board of Yeda Research & Development Co., the Weizmann Institute's technology transfer arm.
Outside the Weizmann Institute, Schmidt was actively involved in Israel's scientific and technological development. From 1960 to 1968, he served on the board of directors of the Dead Sea Works . In 1967, he became a member of the executive committee of the new Center for Industrial Research in Haifa . In addition, from 1967 to 1969, he chaired two committees established by Israel's National Council for Research and Development – on technical applications of photochemistry and on bromine chemistry.
He founded the Israel Crystallography Society and was its first President (1958-1960), negotiating its adherence to the International Union of Crystallography .
In 1963, he received the Weizmann Prize in the Exact Sciences from Tel Aviv municipality for his research on the structure and chemical behavior of crystals.
The Weizmann Institute has established the annual Gerhard M. J. Schmidt Memorial Lecture held in the Schmidt Lecture Hall, and the Gerhard M.J. Schmidt Minerva Center on Supramolecular Architectures, which supports collaboration between Weizmann faculty and German scientists.
Professor Schmidt is recognized as one of the founders of modern organic solid-state chemistry. At the Weizmann Institute, the work of his group centered around the development of X-ray crystallographic methods for the determination of molecular structures in order to understand the properties and reactivity of organic solids.
In the early 1950s, Schmidt investigated the structure and chemistry of over-crowded molecules and their activity. In other studies, he discovered a correlation between the crystalline structure and the symmetry of photochemical products. This finding helped in understanding chemical reactions in organized systems. He then coined the term “topochemistry” for this kind of reaction.
In his research, Schmidt sought to clarify the way by which the structure of molecules affects their packing mode in the crystal . During these studies, he revealed the occurrence of halogen-halogen interactions. Later, he coined the term “crystal engineering,” suggesting that by understanding the ways in which molecules interact, it should be possible to design packing motifs in crystals for rational planning of solid-state reactions. This approach was implemented successfully in the first “absolute” asymmetric synthesis in crystals.
Schmidt's achievements stemmed from his earlier ideas recognizing the importance of combining chemistry with molecular geometry . He also suggested that an ordered arrangement of reactive units in space was the key to understanding biological processes such as photosynthesis and enzymatic activity.
Jack D. Dunitz. Gerhard Schmidt (1919-1971) and the Road to Chemical Crystallography. In: "Solid State Photochemistry. A Collection of Papers by G. M. J. Schmidt and his Collaborators Describing a Symbiotic Relationship between X-Ray Crystallography and Synthetic Organic Photochemistry. Herausgegeben von D. Ginsburg." (edited by David Ginsburg). Monographs in Modern Chemistry, Vol. 8, pp. 255–269. VCH, Weinheim–New York, 1976.
Margaret Thatcher shares her memories of Gerhard Schmidt in a 1985 speech upon the establishment of a Chair bearing her name at the Weizmann Institute
G. M. J. Schmidt: Memorial Volume, Israel Journal of Chemistry ( http://onlinelibrary.wiley.com/doi/10.1002/ijch.v10.2/issuetoc ) Eds.: Cohen M.D., Ginsburg D., Hirshfeld F., 1972, vol. 10, issue 2, pp. 59–658.
G. M. J. Schmidt et al. Solid State Photochemistry. Weinheim: Verlag Chemie, 1976. A collection of papers by Schmidt and his collaborators https://www.amazon.com/Solid-State-Photochemistry-alSchmidt/dp/B002JCCSY8/ref=sr_1_1?s=books&ie=UTF8&qid=1387293920&sr=1-1
L. Leiserowitz, "Overlapping with Jack Dunitz", Israel Journal of Chemistry, EarlyView (2016). https://dx.doi.org/10.1002/ijch.201600001 | https://en.wikipedia.org/wiki/Gerhard_Schmidt_(crystallographer) |
Gerhard Schrader (25 February 1903 – 10 April 1990) was a German chemist specializing in the discovery of new insecticides , hoping to make progress in the fight against hunger in the world. Schrader is best known for his accidental discovery of nerve agents including sarin and tabun . Sarin is partially named after him: It was named in honor of its discoverers, Schrader, Otto Ambros , Gerhard Ritter [ de ] , and Hans-Jürgen von der Linde. [ 1 ]
Schrader was born in Bortfeld, near Wendeburg , Germany. He attended gymnasium in Braunschweig and later studied chemistry at Braunschweig University of Technology . [ 2 ] He was later employed at the Bayer AG division of IG Farben .
Schrader discovered several very effective insecticides, including bladan (the first fully synthetic contact insecticide, Hexaethyl tetraphosphate being a constituent), and parathion (E 605). In 1936, while employed by the large German conglomerate IG Farben , he was experimenting with a class of compounds called organophosphates , which killed insects by interrupting their nervous systems.
Schrader experimented with numerous compounds, eventually leading to the synthesis of Tabun . During World War II , under the Nazi regime, teams led by Schrader discovered two more organophosphate nerve agents, and a fourth after the war:
This article about a German chemist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Gerhard_Schrader |
Gerhart Jander (26 October 1892 – 8 December 1961) was a German inorganic chemist. His book, now normally only called "Jander-Blasius", on analytical chemistry is still used in German universities. His involvement in the chemical weapon research and close relation to the NSDAP have been uncovered by recent research.
Jander was born in Altdöbern , Oberspreewald-Lausitz . Jander studied in Technical University of Munich , and at University of Berlin where he received his Ph.D for work with Arthur Rosenheim in 1917. He joined Richard Zsigmondy at the University of Göttingen . He became professor in 1925 and after a two-year period being a temporary director of the Kaiser Wilhelm Institute for Physical Chemistry and Elektrochemistry from 1933 till 1935 he became professor for inorganic chemistry at the University of Greifswald . In 1951 he changed to Technische Universität Berlin . Jander died in Berlin in 1961. [ 1 ] [ 2 ]
The involvement of Jander in the research on chemical warfare and his influence on the Kaiser Wilhelm Institute for Physical Chemistry and Elektrochemistry after he followed Fritz Haber as director, who was forced to resign due to the Law for the Restoration of the Professional Civil Service , have been a point of research of the Max Planck Society (The Max Planck Society is the successor organisation of the Kaiser Wilhelm Society). [ 3 ] [ 4 ] | https://en.wikipedia.org/wiki/Gerhart_Jander |
Germ-Soma Differentiation is the process by which organisms develop distinct germline and somatic cells. The development of cell differentiation has been one of the critical aspects of the evolution of multicellularity and sexual reproduction in organisms. Multicellularity has evolved upwards of 25 times, [ 1 ] and due to this there is great possibility that multiple factors have shaped the differentiation of cells. There are three general types of cells: germ cells , somatic cells , and stem cells . Germ cells lead to the production of gametes, while somatic cells perform all other functions within the body. Within the broad category of somatic cells, there is further specialization as cells become specified to certain tissues and functions. In addition, stem cell are undifferentiated cells which can develop into a specialized cell and are the earliest type of cell in a cell lineage. [ 2 ] Due to the differentiation in function, somatic cells are found only in multicellular organisms, as in unicellular ones the purposes of somatic and germ cells are consolidated in one cell .
All organisms with germ-soma differentiation are eukaryotic , and represent an added level of specialization to multicellular organisms. Pure germ-soma differentiation has developed in a select number of eukaryotes (called Weismannists ), included in this category are vertebrates and arthropods - however land plants, green algae, red algae, brown algae, and fungi have partial differentiation. [ 3 ] While a significant portion of organisms with germ-soma differentiation are asexual , this distinction has been imperative in the development of sexual reproduction; the specialization of certain cells into germ cells is fundamental for meiosis and recombination .
The strict division between somatic and germ cells is called the Weismann barrier, in which genetic information passed onto offspring is found only in germ cells. This occurs only in select organisms, however some without a Weismann barrier do present germ-soma differentiation. These organisms include land plants , many algaes , invertebrates , and fungi whose germ cells are derived from prior somatic cells as opposed to stem cells. The Weismann barrier is essential to the concept of an immortal germline, which passes down genetic information through designated germ cells.Organisms with germ-soma differentiation but no Weismann barrier often reproduce through somatic embryogenesis . [ citation needed ]
There is no single widely accepted theory on the origins of somatic-germline differentiation, however of those that do exist many are based on the evolutionary advantage of differentiated multicellularity which has allowed it to survive. These theories include the development of colonial organization structures in which the division of labor between cells allowed for improvements in fitness. [ citation needed ]
The division of labor within multicellular organisms can offer significant advantages over unicellular counterparts. Division can allow organisms to become larger, or interact with the environments (and thus fill different niches ) that increase fitness . In addition to internal benefits, there is evidence that these also improve defenses against predation. [ 4 ] On the other hand, multicellularity comes with increased energy use devoted to maintaining homeostasis instead of to reproduction.
One major theory as to the proliferation of organisms with cell differentiation is the dirty work hypothesis. This hypothesis posits that when an organism has differentiated cells, somatic cells are able to devote energy solely to maintaining homeostasis instead of reproduction while germ cells do the opposite. One reason proposed for the relative success of the "dirty work" system of organization is that it helps manage the detrimental effects of metabolic activity , and allow for more efficient energy distribution throughout an organism. [ 5 ] The other major reason proposed is that it prevents metabolic activity within the cell from damaging genetic material. Said activity in mitochondria and chloroplasts creates mutagenic byproducts, so in organisms with differentiation where germ cells do not engage in metabolic activity the germline is not impacted. [ 5 ] [ 6 ]
Due to the nature of research around the origin of life and multicellularity, it has been difficult to obtain a case study that is optimal for observing somatic-germline differentiation. One case that has been extensively studied is that of organisms in the Volvocacaeae family. Within volvocavea, there is much diversity in organizational structure, with some organisms being unicellular , colonial, or (arguably) multicellular. [ 7 ] Within volvocine algae three genes have been identified as crucial to the development of soma cells which regulate coding for asymmetric division of cells, preventing reproductive development of soma cells, and preventing the development of somatic characteristics in germ cells (such as those meant for mobility or metabolic activity [ 8 ] ). | https://en.wikipedia.org/wiki/Germ-Soma_Differentiation |
Germ-band extension is a morphogenic process widely studied in the development of Drosophila melanogaster in which the germ-band , which develops into the segmented trunk of the embryo, approximately doubles in length along the anterior-posterior axis while subsequently narrowing along the dorsal-ventral axis. [ 1 ]
Germ-band extension begins shortly after gastrulation and is divided into two phases. The fast phase, in which most of the extension occurs, takes about 25 minutes. The remaining extension continues during the slow phase and is completed in the following 70 minutes. [ 2 ] During this process the ventral germ-band extends around the posterior end of the embryo, effectively folding over onto the dorsal side of the egg. Multiple individual cells intercalating mediolateral to the anterior-posterior axis drive the resulting global elongation of the embryo. In addition, cell shape changes, and oriented cell divisions in the posterior germ-band are in part required for full elongation. [ 3 ] However, elongation of the body axis seems to be primarily linked to changes in cell neighbor relations.
This article describes axis elongation in Drosophila . However, the basis of germ-band elongation is applicable to many organisms including other invertebrates and vertebrates alike. [ 4 ]
In order for cells to intercalate between one another the adherens junctions that maintain the integrity of the epithelial tissue must be dynamically remodeled. Time-lapse microscopy has captured this process of cell neighbor exchange, which is schematically represented to the right. In the type 1 configuration, two cells contact each other along the anterior-posterior axis, whereas two dorsal-ventral cells do not directly contact. Next, the cell boundary between the two anterior-posterior neighbors selectively shrinks, resulting in an obligatory intermediate type 2 junction, where the four cells share a vertex. Upon resolution of the type 2 junction, a new type 3 junction forms perpendicular to the original type 1 configuration. During this process the two dorsal-ventral cells have become neighbors. [ 5 ] When multiple clusters of cells intercalate in the dorsal-ventral axis, through junctional neighbor exchange, the outcome is an extension of germ-band in the anterior-posterior axis.
In addition to the simple neighbor exchange, higher-ordered rosette formations have been observed in which five or more cells meet at a vertex. Multicellular rosettes form and resolve in a directional fashion that promotes germ-band elongation. [ 6 ] Neighbor exchange and multicellular rosette formation involve oriented junctional remodeling, which indicates that the intercalating cells are intrinsically polarized within the plane of the epithelium.
The dorsal-ventral intercalation of cells during germ-band extension ultimately arises from the asymmetric localization of proteins within individual cells. Immunofluorescence reveals that non-muscle myosin II localizes to the anterior-posterior boundaries of cells, destabilizing adherens junctions, whereas the Bazooka/Par-3 complex localizes to dorsal-ventral boundaries, stabilizing adherens junctions. Moreover, bazooka mutants are defective in germ-band extension, which supports the idea that polarized protein localization is critical for cell rearrangements. [ 7 ] One mechanism by which myosin II might promote polarized cell remodeling is through contractile activity that creates tension orienting junctional disassembly. [ 8 ] However, the precise mechanism in which asymmetrically localized protein complexes encourage directed intercalation remains disputed.
The source that establishes planar polarity during germ-band extension remains elusive. Polarized intercalation is largely unaffected in mutant embryos that lack dorsal-ventral cell types. Yet, mutations that disrupt segmental patterning along the anterior-posterior axis, such as eve and runt , decrease cell intercalation and subsequent germ-band elongation. [ 1 ] Furthermore, ectopic expression of eve or runt is sufficient to locally reorient the polarity of nearby cells. This evidence argues that planar polarity is established by cell-cell interactions, and not by a long-range polarizing cue . Thus, polarizing information can spread from one cell to the next, downstream of an Eve-dependent signal that remains to be identified. [ 7 ]
Researchers suggest that mesoderm invagination provides an anterior-posterior pulling force that contributes to germ-band extension through passive cell shape changes. Although anterior-posterior patterning mutants fail to fully extend their germ-bands, during the fast phase the elongation length is normal despite defects in polarized cell intercalation. Time-lapse analysis revealed that an increase in cell shape stretching in the anterior-posterior axis was compensating for aberrant cell intercalation, independent of anterior-posterior patterning. Furthermore, during wild type development, it has been suggested that intercalary cell behavior relaxes the stress imposed on the germ-band, allowing stretched cells to restore to isometric shapes. [ 3 ]
In addition, there is evidence that mechanical tension is necessary and sufficient for the cortical localization of myosin II. Thus, not only can myosin II generate tension but it may also be up-regulated by tensile forces, creating a positive feedback loop that allows cells to dynamically respond to fluctuations in their mechanical environment. [ 9 ] | https://en.wikipedia.org/wiki/Germ-band_extension |
In mathematics , the notion of a germ of an object in/on a topological space is an equivalence class of that object and others of the same kind that captures their shared local properties. In particular, the objects in question are mostly functions (or maps ) and subsets . In specific implementations of this idea, the functions or subsets in question will have some property, such as being analytic or smooth , but in general this is not needed (the functions in question need not even be continuous ); it is however necessary that the space on/in which the object is defined is a topological space, in order that the word local has some meaning.
The name is derived from cereal germ in a continuation of the sheaf metaphor, as a germ is (locally) the "heart" of a function, as it is for a grain.
Given a point x of a topological space X , and two maps f , g : X → Y {\displaystyle f,g:X\to Y} (where Y is any set ), then f {\displaystyle f} and g {\displaystyle g} define the same germ at x if there is a neighbourhood U of x such that restricted to U , f and g are equal; meaning that f ( u ) = g ( u ) {\displaystyle f(u)=g(u)} for all u in U .
Similarly, if S and T are any two subsets of X , then they define the same germ at x if there is again a neighbourhood U of x such that
It is straightforward to see that defining the same germ at x is an equivalence relation (be it on maps or sets), and the equivalence classes are called germs (map-germs, or set-germs accordingly). The equivalence relation is usually written
Given a map f on X , then its germ at x is usually denoted [ f ] x . Similarly, the germ at x of a set S is written [ S ] x . Thus,
A map germ at x in X that maps the point x in X to the point y in Y is denoted as
When using this notation, f is then intended as an entire equivalence class of maps, using the same letter f for any representative map.
Notice that two sets are germ-equivalent at x if and only if their characteristic functions are germ-equivalent at x :
Maps need not be defined on all of X , and in particular they don't need to have the same domain. However, if f has domain S and g has domain T , both subsets of X , then f and g are germ equivalent at x in X if first S and T are germ equivalent at x , say S ∩ U = T ∩ U ≠ ∅ , {\displaystyle S\cap U=T\cap U\neq \emptyset ,} and then moreover f | S ∩ V = g | T ∩ V {\displaystyle f|_{S\cap V}=g|_{T\cap V}} , for some smaller neighbourhood V with x ∈ V ⊆ U {\displaystyle x\in V\subseteq U} . This is particularly relevant in two settings:
If f and g are germ equivalent at x , then they share all local properties, such as continuity, differentiability etc., so it makes sense to talk about a differentiable or analytic germ , etc. Similarly for subsets: if one representative of a germ is an analytic set then so are all representatives, at least on some neighbourhood of x .
Algebraic structures on the target Y are inherited by the set of germs with values in Y . For instance, if the target Y is a group , then it makes sense to multiply germs: to define [ f ] x [ g ] x , first take representatives f and g , defined on neighbourhoods U and V respectively, and define [ f ] x [ g ] x to be the germ at x of the pointwise product map fg (which is defined on U ∩ V {\displaystyle U\cap V} ). In the same way, if Y is an abelian group , vector space , or ring , then so is the set of germs.
The set of germs at x of maps from X to Y does not have a useful topology , except for the discrete one. It therefore makes little or no sense to talk of a convergent sequence of germs. However, if X and Y are manifolds , then the spaces of jets J x k ( X , Y ) {\displaystyle J_{x}^{k}(X,Y)} (finite order Taylor series at x of map(-germs)) do have topologies as they can be identified with finite-dimensional vector spaces .
The idea of germs is behind the definition of sheaves and presheaves. A presheaf F {\displaystyle {\mathcal {F}}} of abelian groups on a topological space X assigns an abelian group F ( U ) {\displaystyle {\mathcal {F}}(U)} to each open set U in X . Typical examples of abelian groups here are: real-valued functions on U , differential forms on U , vector fields on U , holomorphic functions on U (when X is a complex manifold ), constant functions on U and differential operators on U .
If V ⊆ U {\displaystyle V\subseteq U} then there is a restriction map r e s V U : F ( U ) → F ( V ) , {\displaystyle \mathrm {res} _{VU}:{\mathcal {F}}(U)\to {\mathcal {F}}(V),} satisfying certain compatibility conditions . For a fixed x , one says that elements f ∈ F ( U ) {\displaystyle f\in {\mathcal {F}}(U)} and g ∈ F ( V ) {\displaystyle g\in {\mathcal {F}}(V)} are equivalent at x if there is a neighbourhood W ⊆ U ∩ V {\displaystyle W\subseteq U\cap V} of x with res WU ( f ) = res WV ( g ) (both elements of F ( W ) {\displaystyle {\mathcal {F}}(W)} ). The equivalence classes form the stalk F x {\displaystyle {\mathcal {F}}_{x}} at x of the presheaf F {\displaystyle {\mathcal {F}}} . This equivalence relation is an abstraction of the germ equivalence described above.
Interpreting germs through sheaves also gives a general explanation for the presence of algebraic structures on sets of germs. The reason is that formation of stalks preserves finite limits . This implies that if T is a Lawvere theory and a sheaf F is a T -algebra, then any stalk F x is also a T -algebra.
If X {\displaystyle X} and Y {\displaystyle Y} have additional structure, it is possible to define subsets of the set of all maps from X to Y or more generally sub- presheaves of a given presheaf F {\displaystyle {\mathcal {F}}} and corresponding germs: some notable examples follow .
The stalk of a sheaf F {\displaystyle {\mathcal {F}}} on a topological space X {\displaystyle X} at a point x {\displaystyle x} of X {\displaystyle X} is commonly denoted by F x . {\displaystyle {\mathcal {F}}_{x}.} As a consequence, germs, constituting stalks of sheaves of various kind of functions, borrow this scheme of notation:
For germs of sets and varieties, the notation is not so well established: some notations found in literature include:
The key word in the applications of germs is locality : all local properties of a function at a point can be studied by analyzing its germ . They are a generalization of Taylor series , and indeed the Taylor series of a germ (of a differentiable function) is defined: you only need local information to compute derivatives.
Germs are useful in determining the properties of dynamical systems near chosen points of their phase space : they are one of the main tools in singularity theory and catastrophe theory .
When the topological spaces considered are Riemann surfaces or more generally complex analytic varieties , germs of holomorphic functions on them can be viewed as power series , and thus the set of germs can be considered to be the analytic continuation of an analytic function .
Germs can also be used in the definition of tangent vectors in differential geometry . A tangent vector can be viewed as a point-derivation on the algebra of germs at that point. [ 1 ]
As noted earlier, sets of germs may have algebraic structures such as being rings. In many situations, rings of germs are not arbitrary rings but instead have quite specific properties.
Suppose that X is a space of some sort. It is often the case that, at each x ∈ X , the ring of germs of functions at x is a local ring . This is the case, for example, for continuous functions on a topological space; for k -times differentiable, smooth, or analytic functions on a real manifold (when such functions are defined); for holomorphic functions on a complex manifold ; and for regular functions on an algebraic variety. The property that rings of germs are local rings is axiomatized by the theory of locally ringed spaces .
The types of local rings that arise, however, depend closely on the theory under consideration. The Weierstrass preparation theorem implies that rings of germs of holomorphic functions are Noetherian rings . It can also be shown that these are regular rings . On the other hand, let C 0 ∞ ( R ) {\displaystyle {\mathcal {C}}_{0}^{\infty }(\mathbf {R} )} be the ring of germs at the origin of smooth functions on R . This ring is local but not Noetherian. To see why, observe that the maximal ideal m of this ring consists of all germs that vanish at the origin, and the power m k consists of those germs whose first k − 1 derivatives vanish. If this ring were Noetherian, then the Krull intersection theorem would imply that a smooth function whose Taylor series vanished would be the zero function. But this is false, as can be seen by considering
This ring is also not a unique factorization domain . This is because all UFDs satisfy the ascending chain condition on principal ideals , but there is an infinite ascending chain of principal ideals
The inclusions are strict because x is in the maximal ideal m .
The ring C 0 0 ( R ) {\displaystyle {\mathcal {C}}_{0}^{0}(\mathbf {R} )} of germs at the origin of continuous functions on R even has the property that its maximal ideal m satisfies m 2 = m . Any germ f ∈ m can be written as
where sgn is the sign function. Since | f | vanishes at the origin, this expresses f as the product of two functions in m , whence the conclusion. This is related to the setup of almost ring theory . | https://en.wikipedia.org/wiki/Germ_(mathematics) |
A germ layer is a primary layer of cells that forms during embryonic development . [ 1 ] The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans ( animals that are sister taxa to the sponges ) produce two or three primary germ layers. Some animals, like cnidarians , produce two germ layers (the ectoderm and endoderm ) making them diploblastic . Other animals such as bilaterians produce a third layer (the mesoderm ) between these two layers, making them triploblastic . Germ layers eventually give rise to all of an animal's tissues and organs through the process of organogenesis .
Caspar Friedrich Wolff observed organization of the early embryo in leaf-like layers. In 1817, Heinz Christian Pander discovered three primordial germ layers while studying chick embryos. Between 1850 and 1855, Robert Remak had further refined the germ cell layer ( Keimblatt ) concept, stating that the external, internal and middle layers form respectively the epidermis, the gut, and the intervening musculature and vasculature. [ 2 ] [ 3 ] [ 4 ] The term " mesoderm " was introduced into English by Huxley in 1871, and " ectoderm " and " endoderm " by Lankester in 1873.
Among animals , sponges show the least amount of compartmentalization, having a single germ layer. Although they have differentiated cells (e.g. collar cells ), they lack true tissue coordination. Diploblastic animals, Cnidaria and Ctenophora , show an increase in compartmentalization, having two germ layers, the endoderm and ectoderm . Diploblastic animals are organized into recognisable tissues. All bilaterian animals (from flatworms to humans) are triploblastic , possessing a mesoderm in addition to the germ layers found in Diploblasts. Triploblastic animals develop recognizable organs.
Fertilization leads to the formation of a zygote . During the next stage, cleavage , mitotic cell divisions transform the zygote into a hollow ball of cells, a blastula . This early embryonic form undergoes gastrulation , forming a gastrula with either two or three layers (the germ layers). In all vertebrates , these progenitor cells differentiate into all adult tissues and organs. [ 5 ]
In the human embryo , after about three days, the zygote forms a solid mass of cells by mitotic division, called a morula . This then changes to a blastocyst , consisting of an outer layer called a trophoblast , and an inner cell mass called the embryoblast . Filled with uterine fluid, the blastocyst breaks out of the zona pellucida and undergoes implantation . The inner cell mass initially has two layers: the hypoblast and epiblast . At the end of the second week, a primitive streak appears. The epiblast in this region moves towards the primitive streak, dives down into it, and forms a new layer, called the endoderm , pushing the hypoblast out of the way (this goes on to form the amnion .) The epiblast keeps moving and forms a second layer, the mesoderm . The top layer is now called the ectoderm . [ 6 ]
Gastrulation occurs in reference to the primary body axis . Germ layer formation is linked to the primary body axis as well, however it is less reliant on it than gastrulation is. Hydractinia shows that germ layer formation that transpires as a mixed delamination. [ 7 ]
In mice, germ layer differentiation is controlled by two transcription factors : Sox2 and Oct4 proteins. These transcription factors cause the pluripotent mouse embryonic stem cells to select a germ layer fate. Sox2 promotes ectodermal differentiation, while Oct4 promotes mesendodermal differentiation. Each gene inhibits what the other promotes. Amounts of each protein are different throughout the genome, causing the embryonic stem cells to select their fate. [ 8 ]
The endoderm is one of the germ layers formed during animal embryonic development . Cells migrating inward along the archenteron form the inner layer of the gastrula , which develops into the endoderm .
The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of the whole of the digestive tract except part of the mouth and pharynx and the terminal part of the rectum (which are lined by involutions of the ectoderm). It also forms the lining cells of all the glands which open into the digestive tract, including those of the liver and pancreas; the epithelium of the auditory tube and tympanic cavity; the trachea, bronchi, and alveoli of the lungs; the bladder and part of the urethra; and the follicle lining of the thyroid gland and thymus.
The endoderm forms: the pharynx , the esophagus , the stomach , the small intestine , the colon , the liver , the pancreas , the bladder , the epithelial parts of the trachea and bronchi , the lungs , the thyroid , and the parathyroid .
The mesoderm germ layer forms in the embryos of triploblastic animals . During gastrulation , some of the cells migrating inward contribute to the mesoderm, an additional layer between the endoderm and the ectoderm . [ 9 ] The formation of a mesoderm leads to the development of a coelom . Organs formed inside a coelom can freely move, grow, and develop independently of the body wall while fluid cushions protects them from shocks. [ 10 ]
The mesoderm has several components which develop into tissues: intermediate mesoderm , paraxial mesoderm , lateral plate mesoderm , and chorda-mesoderm . The chorda-mesoderm develops into the notochord. The intermediate mesoderm develops into kidneys and gonads. The paraxial mesoderm develops into cartilage, skeletal muscle, and dermis. The lateral plate mesoderm develops into the circulatory system (including the heart and spleen), the wall of the gut, and wall of the human body. [ 11 ]
Through cell signaling cascades and interactions with the ectodermal and endodermal cells, the mesodermal cells begin the process of differentiation . [ 12 ]
The mesoderm forms: muscle ( smooth and striated ), bone , cartilage , connective tissue , adipose tissue , circulatory system , lymphatic system , dermis , dentine of teeth, genitourinary system , serous membranes , spleen and notochord .
The ectoderm generates the outer layer of the embryo, and it forms from the embryo's epiblast . [ 13 ] The ectoderm develops into the surface ectoderm , neural crest , and the neural tube . [ 14 ]
The surface ectoderm develops into: epidermis , hair , nails , lens of the eye , sebaceous glands , cornea , tooth enamel , the epithelium of the mouth and nose .
The neural crest of the ectoderm develops into: peripheral nervous system , adrenal medulla , melanocytes , facial cartilage.
The neural tube of the ectoderm develops into: brain , spinal cord , posterior pituitary , motor neurons , retina .
Note: The anterior pituitary develops from the ectodermal tissue of Rathke's pouch .
Because of its great importance, the neural crest is sometimes considered a fourth germ layer. [ 15 ] It is, however, derived from the ectoderm. | https://en.wikipedia.org/wiki/Germ_layer |
Germ theory denialism is the pseudoscientific belief that germs do not cause infectious disease, and that the germ theory of disease is wrong. [ 1 ] It usually involves arguing that Louis Pasteur 's model of infectious disease was wrong, and that Antoine Béchamp 's was right. In fact, its origins are rooted in Béchamp's empirically disproven (in the context of disease) theory of pleomorphism . [ 2 ] Another obsolete variation is known as terrain theory and postulates that germs morphologically change in response to environmental factors, subsequently causing disease, rather than germs being the sole cause of it. [ 3 ]
Germ theory denialism is as old as germ theory itself, beginning with the rivalry of Pasteur and Béchamp. Pasteur's work in preventing beverage contamination led him to discover that it was due to microorganisms and led him to become the first scientist to prove the validity of the theory and to popularize it in Europe. [ 2 ] Before him, scientists such as Girolamo Fracastoro (who had the idea that fomites could harbor the seeds of contagion), Agostino Bassi (who discovered that the muscardine disease of silkworms was caused by a fungus that was named Beauveria bassiana ), Friedrich Henle (who developed the concepts of contagium vivum and contagium animatum ), and others had proposed ideas similar to germ theory. [ 4 ] [ 5 ]
Béchamp strongly contested Pasteur's view, proposing a competing idea known as the pleomorphic theory of disease. This theory says that all life is based on forms that a certain class of organisms take during stages of their life cycles and that germs are attracted to the environment of diseased tissue rather than being the cause of it. [ 6 ] Proponents of this idea insist that microbes that live in an organism go through the same stages of their development. According to Günther Enderlein , the stages are as follows: [ 7 ]
The terrain theory is a variation of Béchamp's ideas that is also an obsolete medical theory that held that diseases were caused by the composition of the body. The "terrain", will attract germs to come as scavengers of the weakened or poorly defended tissue. Béchamp believed that the pH of the body is important, and that an acidic pH will attract germs and an alkaline pH will repel them. Pasteur disproved spontaneous generation with a series of experiments in the 1870s. [ 4 ] However, understanding the cause of a sickness does not always immediately lead to effective treatment of sickness, and the great decline in mortality during the 19th century stemmed mostly from improvements in hygiene and cleanliness. In fact, one of the first movements to deny the germ theory, the Sanitary Movement , was nevertheless central in developing America's public health infrastructure. Providing clean water and sanitation reduced the environment for pathogens to develop, and mortality rates fell dramatically. [ 8 ] [ 9 ] [ 10 ]
Germ theory denialism is counter to over a century of experiments and practical observations, and the prevailing opinion of almost all doctors and scientists. [ 1 ] [ 2 ] [ 11 ]
A common thread among many alternative medicine proponents is opposition to vaccines , and some use their disbelief in germ theory to justify their claims. [ 12 ] Germ theory deniers make many claims about the biological underpinnings of the theory and the historical record [ 13 ] [ 14 ] that are at odds with what most modern scientists and historians accept. [ 1 ] [ 2 ] [ 4 ] [ 15 ] Another claim from the anti-vaccine community involves the theory that all diseases are caused by toxins due to inadequate diet and health practices. [ 16 ] | https://en.wikipedia.org/wiki/Germ_theory_denialism |
The germ theory of disease is the currently accepted scientific theory for many diseases . It states that microorganisms known as pathogens or "germs" can cause disease. These small organisms, which are too small to be seen without magnification, invade animals, plants, and even bacteria . Their growth and reproduction within their hosts can cause disease. "Germ" refers not just to bacteria but to any type of microorganism, such as protists or fungi , or other pathogens, including parasites , viruses , prions , or viroids . [ 1 ] Diseases caused by pathogens are called infectious diseases . Even when a pathogen is the principal cause of a disease, environmental and hereditary factors often influence the severity of the disease, and whether a potential host individual becomes infected when exposed to the pathogen. Pathogens are disease-causing agents that can pass from one individual to another, across multiple domains of life.
Basic forms of germ theory were proposed by Girolamo Fracastoro in 1546, and expanded upon by Marcus von Plenciz in 1762. However, such views were held in disdain in Europe, where Galen's miasma theory remained dominant among scientists and doctors.
By the early 19th century, the first vaccine , smallpox vaccination , was commonplace in Europe, though doctors were unaware of how it worked or how to extend the principle to other diseases. A transitional period began in the late 1850s with the work of Louis Pasteur . This work was later extended by Robert Koch in the 1880s. By the end of that decade, the miasma theory was struggling to compete with the germ theory of disease. Viruses were initially discovered in the 1890s. Eventually, a "golden era" of bacteriology ensued, during which the germ theory quickly led to the identification of the actual organisms that cause many diseases. [ 2 ]
The miasma theory was the predominant theory of disease transmission before the germ theory took hold towards the end of the 19th century; it is no longer accepted as a correct explanation for disease by the scientific community. It held that diseases such as cholera , chlamydia infection , or the Black Death were caused by a miasma ( μίασμα , Ancient Greek : "pollution"), a noxious form of "bad air" emanating from rotting organic matter. [ 3 ] Miasma was considered to be a poisonous vapor or mist filled with particles from decomposed matter (miasmata) that was identifiable by its foul smell. The theory posited that diseases were the product of environmental factors such as contaminated water, foul air, and poor hygienic conditions. Such infections, according to the theory, were not passed between individuals but would affect those within a locale that gave rise to such vapors. [ 4 ]
In Antiquity , the Greek historian Thucydides ( c. 460 – c. 400 BC ) was the first person to write, in his account of the plague of Athens , that diseases could spread from an infected person to others. [ 5 ] [ 6 ]
One theory of the spread of contagious diseases that were not spread by direct contact was that they were spread by spore -like "seeds" ( Latin : semina ) that were present in and dispersible through the air. In his poem, De rerum natura (On the Nature of Things, c. 56 BC ), the Roman poet Lucretius ( c. 99 BC – c. 55 BC ) stated that the world contained various "seeds", some of which could sicken a person if they were inhaled or ingested. [ 7 ] [ 8 ]
The Roman statesman Marcus Terentius Varro (116–27 BC) wrote, in his Rerum rusticarum libri III (Three Books on Agriculture, 36 BC): "Precautions must also be taken in the neighborhood of swamps... because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and there cause serious diseases." [ 9 ]
The Greek physician Galen (AD 129 – c. 200/216 ) speculated in his On Initial Causes ( c. 175 AD ) that some patients might have "seeds of fever". [ 7 ] : 4 In his On the Different Types of Fever ( c. 175 AD ), Galen speculated that plagues were spread by "certain seeds of plague", which were present in the air. [ 7 ] : 6 And in his Epidemics ( c. 176–178 AD ), Galen explained that patients might relapse during recovery from fever because some "seed of the disease" lurked in their bodies, which would cause a recurrence of the disease if the patients did not follow a physician's therapeutic regimen. [ 7 ] : 7
A hybrid form of miasma and contagion theory was proposed by Persian physician Ibn Sina (known as Avicenna in Europe) in The Canon of Medicine (1025). He mentioned that people can transmit disease to others by breath, noted contagion with tuberculosis , and discussed the transmission of disease through water and dirt. [ 10 ]
During the early Middle Ages, Isidore of Seville ( c. 560 –636) mentioned "plague-bearing seeds" ( pestifera semina ) in his On the Nature of Things ( c. AD 613 ). [ 7 ] : 20 Later in 1345, Tommaso del Garbo ( c. 1305 –1370) of Bologna, Italy mentioned Galen's "seeds of plague" in his work Commentaria non-parum utilia in libros Galeni (Helpful commentaries on the books of Galen). [ 7 ] : 214
The 16th century Reformer Martin Luther appears to have had some idea of the contagion theory, commenting, "I have survived three plagues and visited several people who had two plague spots which I touched. But it did not hurt me, thank God. Afterwards when I returned home, I took up Margaret," (born 1534), "who was then a baby, and put my unwashed hands on her face, because I had forgotten; otherwise I should not have done it, which would have been tempting God." [ 11 ] In 1546, Italian physician Girolamo Fracastoro published De Contagione et Contagiosis Morbis ( On Contagion and Contagious Diseases ), a set of three books covering the nature of contagious diseases, categorization of major pathogens, and theories on preventing and treating these conditions. Fracastoro blamed "seeds of disease" that propagate through direct contact with an infected host, indirect contact with fomites , or through particles in the air. [ 12 ]
In 1668, Italian physician Francesco Redi published experimental evidence rejecting spontaneous generation , the theory that living creatures arise from nonliving matter. He observed that maggots only arose from rotting meat that was uncovered. When meat was left in jars covered by gauze, the maggots would instead appear on the gauze's surface, later understood as rotting meat's smell passing through the mesh to attract flies that laid eggs. [ 13 ] [ 14 ]
Microorganisms are said to have been first directly observed in the 1670s by Anton van Leeuwenhoek , an early pioneer in microbiology , considered "the Father of Microbiology". Leeuwenhoek is said to be the first to see and describe bacteria in 1674, yeast cells, the teeming life in a drop of water (such as algae), and the circulation of blood corpuscles in capillaries. The word "bacteria" didn't exist yet, so he called these microscopic living organisms "animalcules", meaning "little animals". Those "very little animalcules" he was able to isolate from different sources, such as rainwater, pond and well water, and the human mouth and intestine.
Yet German Jesuit priest and scholar Athanasius Kircher (or "Kirchner", as it is often spelled) may have observed such microorganisms prior to this. One of his books written in 1646 contains a chapter in Latin, which reads in translation: "Concerning the wonderful structure of things in nature, investigated by microscope...who would believe that vinegar and milk abound with an innumerable multitude of worms." Kircher defined the invisible organisms found in decaying bodies, meat, milk, and secretions as "worms." His studies with the microscope led him to the belief, which he was possibly the first to hold, that disease and putrefaction, or decay were caused by the presence of invisible living bodies, writing that "a number of things might be discovered in the blood of fever patients." When Rome was struck by the bubonic plague in 1656, Kircher investigated the blood of plague victims under the microscope. He noted the presence of "little worms" or "animalcules" in the blood and concluded that the disease was caused by microorganisms.
Kircher was the first to attribute infectious disease to a microscopic pathogen, inventing the germ theory of disease, which he outlined in his Scrutinium Physico-Medicum , published in Rome in 1658. [ 15 ] Kircher's conclusion that disease was caused by microorganisms was correct, although it is likely that what he saw under the microscope were in fact red or white blood cells and not the plague agent itself. Kircher also proposed hygienic measures to prevent the spread of disease, such as isolation, quarantine, burning clothes worn by the infected, and wearing facemasks to prevent the inhalation of germs. It was Kircher who first proposed that living beings enter and exist in the blood.
In the 18th century, more proposals were made, but struggled to catch on. In 1700, physician Nicolas Andry argued that microorganisms he called "worms" were responsible for smallpox and other diseases. [ 16 ] In 1720, Richard Bradley theorised that the plague and "all pestilential distempers" were caused by "poisonous insects", living creatures viewable only with the help of microscopes. [ 17 ]
In 1762, the Austrian physician Marcus Antonius von Plenciz (1705–1786) published a book titled Opera medico-physica . It outlined a theory of contagion stating that specific animalcules in the soil and the air were responsible for causing specific diseases. Von Plenciz noted the distinction between diseases which are both epidemic and contagious (like measles and dysentery), and diseases which are contagious but not epidemic (like rabies and leprosy). [ 18 ] The book cites Anton van Leeuwenhoek to show how ubiquitous such animalcules are and was unique for describing the presence of germs in ulcerating wounds. Ultimately, the theory espoused by von Plenciz was not accepted by the scientific community.
During the early 19th century, driven by economic concerns over collapsing silk production, Italian entomologist Agostino Bassi researched a silkworm disease known as "muscardine" in French and "calcinaccio" or "mal del segno" in Italian, causing white fungal spots along the caterpillar. From 1835 to 1836, Bassi published his findings that fungal spores transmitted the disease between individuals. In recommending the rapid removal of diseased caterpillars and disinfection of their surfaces, Bassi outlined methods used in modern preventative healthcare . [ 19 ] Italian naturalist Giuseppe Gabriel Balsamo-Crivelli named the causative fungal species after Bassi, currently classified as Beauveria bassiana . [ 20 ]
In 1838 French specialist in tropical medicine Louis-Daniel Beauperthuy pioneered using microscopy in relation to diseases and independently developed a theory that all infectious diseases were due to parasitic infection with " animalcules " (microorganisms). With the help of his friend M. Adele de Rosseville, he presented his theory in a formal presentation before the French Academy of Sciences in Paris. By 1853, he was convinced that malaria and yellow fever were spread by mosquitos. He even identified the particular group of mosquitos that transmit yellow fever as the "domestic species" of "striped-legged mosquito", which can be recognised as Aedes aegypti , the actual vector. He published his theory in 1854 in the Gaceta Oficial de Cumana ("Official Gazette of Cumana"). His reports were assessed by an official commission, which discarded his mosquito theory. [ 21 ]
Ignaz Semmelweis , a Hungarian obstetrician working at the Vienna General Hospital ( Allgemeines Krankenhaus ) in 1847, noticed the dramatically high maternal mortality from puerperal fever following births assisted by doctors and medical students. However, those attended by midwives were relatively safe. Investigating further, Semmelweis made the connection between puerperal fever and examinations of delivering women by doctors, and further realized that these physicians had usually come directly from autopsies . Asserting that puerperal fever was a contagious disease and that matter from autopsies was implicated in its spread, Semmelweis made doctors wash their hands with chlorinated lime water before examining pregnant women. He then documented a sudden reduction in the mortality rate from 18% to 2.2% over a period of a year. Despite this evidence, he and his theories were rejected by most of the contemporary medical establishment. [ 22 ]
Gideon Mantell , the Sussex doctor more famous for discovering dinosaur fossils , spent time with his microscope, and speculated in his Thoughts on Animalcules (1850) that perhaps "many of the most serious maladies which afflict humanity, are produced by peculiar states of invisible animalcular life". [ 23 ]
British physician John Snow is credited as a founder of modern epidemiology for studying the 1854 Broad Street cholera outbreak . [ 24 ] Snow criticized the Italian anatomist Giovanni Maria Lancisi for his early 18th century writings that claimed swamp miasma spread malaria, rebutting that bad air from decomposing organisms was not present in all cases. In his 1849 pamphlet On the Mode of Communication of Cholera, Snow proposed that cholera spread through the fecal–oral route , replicating in human lower intestines . [ 25 ]
In the book's second edition, published in 1855, Snow theorized that cholera was caused by cells smaller than human epithelial cells, leading to Robert Koch's 1884 confirmation of the bacterial species Vibrio cholerae as the causative agent. In recognizing a biological origin, Snow recommended boiling and filtering water, setting the precedent for modern boil-water advisory directives. [ 25 ]
Through a statistical analysis tying cholera cases to specific water pumps associated with the Southwark and Vauxhall Waterworks Company , which supplied sewage-polluted water from the River Thames , Snow showed that areas supplied by this company experienced fourteen times as many deaths as residents using Lambeth Waterworks Company pumps that obtained water from the upriver, cleaner Seething Wells . While Snow received praise for convincing the Board of Guardians of St James's Parish to remove the handles of contaminated pumps, he noted that the outbreak's cases were already declining as scared residents fled the region. [ 25 ]
During the mid-19th century, French microbiologist Louis Pasteur showed that treating the female genital tract with boric acid killed the microorganisms causing postpartum infections while avoiding damage to mucous membranes . [ 26 ]
Building on Redi's work, Pasteur disproved spontaneous generation by constructing swan neck flasks containing nutrient broth. Since the flask contents were only fermented when in direct contact with the external environment's air by removing the curved tubing, Pasteur demonstrated that bacteria must travel between sites of infection to colonize environments. [ 27 ]
Similar to Bassi, Pasteur extended his research on germ theory by studying pébrine , a disease that causes brown spots on silkworms. [ 20 ] While Swiss botanist Carl Nägeli discovered the fungal species Nosema bombycis in 1857, Pasteur applied the findings to recommend improved ventilation and screening of silkworm eggs, an early form of disease surveillance . [ 27 ]
In 1884, German bacteriologist Robert Koch published four criteria for establishing causality between specific microorganisms and diseases, now known as Koch's postulates : [ 28 ]
During his lifetime, Koch recognized that the postulates were not universally applicable, such as asymptomatic carriers of cholera violating the first postulate. For this same reason, the third postulate specifies "should", rather than "must", because not all host organisms exposed to an infectious agent will acquire the infection, potentially due to differences in prior exposure to the pathogen. [ 29 ] [ 30 ] Limiting the second postulate, it was later discovered that viruses cannot be grown in pure cultures because they are obligate intracellular parasites, making it impossible to fulfill the second postulate. [ 31 ] [ 32 ] Similarly, pathogenic misfolded proteins, known as prions , only spread by transmitting their structure to other proteins, rather than self-replicating. [ 33 ]
While Koch's postulates retain historical importance for emphasizing that correlation does not imply causation , many pathogens are accepted as causative agents of specific diseases without fulfilling all of the criteria. [ 34 ] In 1988, American microbiologist Stanley Falkow published a molecular version of Koch's postulates to establish correlation between microbial genes and virulence factors . [ 35 ]
After reading Pasteur's papers on bacterial fermentation, British surgeon Joseph Lister recognized that compound fractures , involving bones breaking through the skin, were more likely to become infected due to exposure to environmental microorganisms. He recognized that carbolic acid could be applied to the site of injury as an effective antiseptic. [ 36 ] | https://en.wikipedia.org/wiki/Germ_theory_of_disease |
Germabenzene (C 5 H 6 Ge) is the parent representative of a group of chemical compounds containing in their molecular structure a benzene ring with a carbon atom replaced by a germanium atom. Germabenzene itself has been studied theoretically, [ 1 ] and synthesized with a bulky 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl or Tbt group. [ 2 ] Also, stable naphthalene derivatives do exist in the laboratory such as the 2-germanaphthalene-containing substance represented below. [ 3 ] The germanium to carbon bond in this compound is shielded from potential reactants by a Tbt group. This compound is aromatic just as the other carbon group representatives silabenzene and stannabenzene . | https://en.wikipedia.org/wiki/Germabenzene |
The Deutsche Luftfahrtforschungsanstalt (LFA/German Aeronautical Research Institute, also known as the Hermann Göring Research Institute ) [ 1 ] was a secret German facility for airframe , aeroengine , and aircraft weapons testing during the Second World War . [ 2 ] It was located near Völkenrode , on the western outskirts of Braunschweig (Brunswick), near what became the Inner German Border . [ 3 ] The site was Germany's "most advanced and extensive [aviation] research establishment, [ 4 ] outside of the existing Erprobungsstelle network of military aviation evaluation facilities, themselves headquartered at Rechlin .
It was a 1,000-acre (400 ha) site begun in October 1935. The first wind tunnel was begun in November 1936. [ 5 ] Most of the sixty buildings, scattered around the site, did not exceed treetop height, and all were well- camouflaged , [ 6 ] to reduce the chance of them being detected by aerial reconnaissance and to avoid making them targets, as the wind tunnels of the Deutsche Versuchsanstalt für Luftfahrt ( DVL ) in Adlershof (near Berlin ) or the Aerodynamische Versuchsanstalt ( AVA , part of today's DLR agency ) at the University of Göttingen were. [ 7 ]
The buildings were in five groups. [ 8 ] The Institute of Aerodynamics had five wind tunnels , while the Institute of Gas Dynamics had its own high-speed tunnel; both were at the southern end of the campus. [ 9 ] The static testing station of the Institute of Strength Properties was to the west; [ 10 ] the Institute of Engine Research, the east. [ 11 ] Weapons research was done by the Institute of Kinematics in a 400 m (1,300 ft)-long tunnel in the northwest corner. [ 12 ] These were accompanied by administration buildings, a canteen , a telephone exchange , guard houses, generators, and other facilities.
To help reduce the risk of detection, there were no railway lines in, nor overhead power lines, nor any chimneys; and uniquely for an aviation research facility of its time in Germany, no runways, taxiways or hardstands for active aviation operations; just about all of the facility's infrastructure needs were supplied underground from Braunschweig, including steam heat . [ 13 ]
In addition, there were four hundred houses in Völkenrode for the 1,500 or so workers and scientists. [ 14 ]
Each of the wind tunnels at LFA was given an "A" number. A1 had a circular nozzle 2.5 m (8 ft 2 in) in diameter, producing a maximum speed of 123 mph (198 km/h; 107 kn); it entered service in 1937, the year after construction began on facilities. [ 15 ] A2 measured 4 m (13 ft 1 in) long and had a test section 2.8 m (9 ft 2 in) in diameter (coated with Keratylene to keep the flow smooth), [ 16 ] capable of generating test speeds (depending on the model's scale ) of between Mach 1 and 1.2. [ 17 ] It was driven by a pair of 600 kW (800 hp) DC electric motors , and fitted with interferometer and striation gear for study of flow patterns. Begun in 1937, it first ran in 1939. [ 18 ] It did, however, suffer with problems of vibration, [ 19 ] leading the research teams to rely on a Rheinmetall-Börsig F25 free-flight research rocket with models mounted in the nose. [ 20 ] The A3 tunnel, largest at the LFA site, had an 8 m (26 ft 3 in) test section with a maximum speed of 95 m/s (210 mph; 185 kn) and a working length of 11 m (36 ft 1 in), enough to accommodate a Messerschmitt Bf 109 's fuselage. [ 21 ] It was powered by a pair of 6 MW (8,000 hp; 8,200 PS). [ 22 ] The A9 building housed a pair of supersonic wind tunnels, each driven by a 4 MW (5,400 hp; 5,400 PS) motor, with a maximum speed of Mach 1.5, but a test section diameter of only 80 cm 2 (12 in 2 ). [ 23 ]
Along with direct aerodynamic research, LFA did testing on materials (though not, apparently, of parts) and on aircraft engines. [ 24 ] The engine work included testing of turbine and turbine blade shapes, ceramic turbine blades, cooling of turbine blades (including liquid cooling), bearings, detonation , and several types of heat exchangers , among other things. [ 25 ]
The test centre assisted the BMW firm in developing the factory-produced forward cowling — which had the engine's oil cooler integrated into it from the beginning — for their BMW 801 fourteen-cylinder radial engine used in many German Luftwaffe military aircraft, most importantly the Focke-Wulf Fw 190 A; [ 26 ] trials indicated it was possible to reduce drag enough to save 150–200 hp (110–150 kW; 150–200 PS), [ 27 ] as well as to maximize pressure build-up to assist cooling. [ 28 ] It also helped in development of the pioneering Argus As 014 pulsejet used in the V-1 . In collaboration with Göttingen and DVL (Berlin- Adlershof ), it also contributed to the development of the swept wing (what Germans called Pfeilflügel , or "arrow wing"). [ 29 ]
Among the engine projects worked on at LFA was a toroidal (swing-piston) design by Otto Lutz of Büssing , a concept akin to the Wankel ; work was also done by Junkers and Bosch . [ 30 ]
LFA remained so secret, the Allied air forces never bombed it. [ 31 ]
Postwar, the Fedden Mission of a Ministry of Aircraft Production team led by Roy Fedden visited the site. [ 32 ] | https://en.wikipedia.org/wiki/German_Aeronautical_Research_Institute |
The German Ageing Survey (DEAS) is a main source of information about ageing and old age as a stage of life in Germany. It is a nationally representative , cross-sectional and longitudinal survey of people in the second half of life (i. e. aged 40 and over).
The comprehensive study of people in their mid- and older adulthood provides individual data for use both in social and behavioural scientific research and in reporting on social developments. The data is thus a source of information for political decision makers, the general public and for scientific research. The DEAS allows to form a comprehensive picture of life situations and life contexts of old and ageing people in Germany and to respond to current political and academic questions. [ 1 ]
The German Ageing Survey (DEAS) is funded by the Federal Ministry for Family Affairs, Senior Citizens, Women and Youth (BMFSFJ). The first survey wave was conducted in 1996. It was designed and carried out by the research group on ageing and the life course from the Freie Universität Berlin , the research group on psychogerontology of the University of Nijmegen and infas Institute for Applied Social Sciences, Bonn. From 2000 onwards, the German Centre of Gerontology (DZA) was responsible for the implementation and further development of the project. The second survey wave of DEAS followed in 2002, the third in 2008, the fourth in 2011, the fifth in 2014, the sixth in 2017, and the seventh in 2020. The data assessments are furthermore carried out by infas Institute for Applied Social Sciences. Starting from 2008, the DEAS panel is conducted every three years. A new cross-sectional sample is drawn every six years. This approach enables the investigation of social change as well as individual development over a 24-year span. A book containing about women and men in the second half of life, containing the key findings of the sixth wave, was published in 2019. [ 2 ] Since 2020 several volumes of the DZA Aktuell, based on the seventh wave and concerning the effects of the corona pandemic on older people, have been published.
Covering a broad spectrum of topics, the DEAS reflects the complex life situations and life concepts of the German population in the second half of life. The survey’s interdisciplinary conception allows for the linking of gerontological , sociological , psychological , socio-political , nursing science, and economic issues. In every new wave the questions aim to balance actuality and continuity. On the one hand, adaptation of the questionnaire to accommodate new insights makes it possible to respond promptly to urgent political and academic questions. On the other hand, the retention of a sizable number of questions from the previous waves ensures comparability and the monitoring of long-term developments.
The following topics are examined:
This broad spectrum of topics makes it necessary to examine them as a whole and to analyse their interrelationship and interactions during the life course. Some examples for this are issues relating to quality of life in old age and social inequality .
The German Ageing Survey enables analyses of cohort differences, i.e. a comparison of individuals of the same age at different points in time and thus an examination of social change . Moreover, it allows longitudinal analyses, i.e. the comparison of information at certain points in time and hence a study of individual developments over time. The DEAS makes possible a comprehensive description of life situations and life contexts of the German population aged over 40 in the year 2014 (current cross-sectional analysis), an analysis of social changes over the points in time 1996, 2002, 2008 and 2014 and an investigation of intra-individual development over either six, twelve, fifteen, eighteen years, twenty-one or twenty-four years (1996-2002, 1996-2002-2008, 1996-2002-2008-2011, 1996-2002-2008-2011-2014 or 1996-2002-2008-2011-2014-2017-2020). Another perspective results from the comparison of individual development over a six-year period in the three time-frames 1996 to 2002, 2002 to 2008 or 2008 to 2014, i.e. a comparison between the development of two or three birth cohorts in a specific age segment.
The findings of the German Ageing Survey are published in edited volumes, refereed journals and press informations. Press information is free of charge and available online at [1] , where you will also find a list of selected DEAS publications in English.
The Research Data Centre of the German Centre of Gerontology (FDZ-DZA) now also provides anonymised data sets for research purposes and advises researchers on its use. | https://en.wikipedia.org/wiki/German_Ageing_Survey |
The German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig is a DFG research center with staff and members at its main locations in Halle , Jena and Leipzig . It is a central facility of Leipzig University , and is run together with the Martin Luther University Halle-Wittenberg and Friedrich Schiller University Jena , as well as in cooperation with the Helmholtz Centre for Environmental Research - UFZ. In addition, seven non-university research institutions belong to the iDiv consortium. iDiv was founded in 2012 and is funded by the DFG.
Due to a great need for research to facilitate implementation of the National Strategy on Biological Diversity, the DFG developed the idea of having its own collaborative research centre for biodiversity. Finally, an institution in the form of a DFG research centre was decided upon.
In the time leading up to October 2010, 15 universities applied to the DFG for establishment of the research centre. The concepts of the FU Berlin, the University of Göttingen, the University Network Halle-Jena-Leipzig and the University of Oldenburg were preselected in July 2011 by the DFG Senate. The FU Berlin and the University Network Halle-Jena-Leipzig were then shortlisted.
On April 27, 2012, came the decision in favour of the University Network Halle-Jena-Leipzig and for the establishment of the core centre at the Leipzig location. At its meeting in Bonn, the DFG's central committee selected the joint application of the Universities of Halle, Jena and Leipzig on the recommendation of the DFG Senate. The scientific and structural conditions at the three neighbouring locations are excellent, and the fact that they already had a strong reputation and had conducted numerous, in some instances internationally oriented research projects in the field of biodiversity science before the opening of the research centre influenced the DFG in its decision. In addition, eight non-university research institutions are involved in the new centre: the Helmholtz Centre for Environmental Research - UFZ, the Max Planck Institute for Biogeochemistry , the Max Planck Institute for Chemical Ecology , the Max Planck Institute for Evolutionary Anthropology , the Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures , the Leibniz Institute of Plant Biochemistry , the Leibniz Institute of Plant Genetics and Crop Plant Research and the Leibniz Institute Senckenberg Museum of Natural History Görlitz (SMNG) .
In autumn 2012, the centre moved to the Biocity at Deutscher Platz 5 in the southeast of the city of Leipzig.
iDiv moved into a new building at the Alte Messe area in 2021. [ 1 ]
The DFG funds iDiv in the current, second funding period (2016-2020) with approximately 9 million euros annually. This represents an increase of 32 percent compared to the first funding period. In addition, the partners in the iDiv consortium make their own contributions and there are also third-party grants for individual research projects. The DFG usually funds DFG research centres such as iDiv for three four-year periods.
Biodiversity research at iDiv takes place against the backdrop of the current biodiversity crisis. The magnitude of it, the underlying processes and consequences for humanity are often unknown. In order to better understand the complex interactions, iDiv research prioritises synthesis, theory and transdisciplinarity. iDiv has two missions:
First, to provide a scientific basis for the sustainable use of our planet's biodiversity.
Second, to develop a new field of research: ‘Integrative Biodiversity Research’
iDiv has four speakers, which are currently Christian Wirth (representing Leipzig University), Nicole van Dam (representing Friedrich Schiller University Jena), Henrique Miguel Pereira (representing Martin Luther University Halle-Wittenberg) and Tiffany M. Knight (representing the Helmholtz Centre for Environmental Research – UFZ).
To date, nine full professors have been appointed:
• Experimental Interaction Ecology (Nico Eisenhauer)
• Biodiversity Conservation (Henrique Miguel Pereira)
• Ecosystem Services (Aletta Bonn)
• Molecular Interaction Ecology (Nicole van Dam)
• Physiological Diversity (Stanley Harpole)
• Biodiversity Synthesis (Jonathan Chase)
• Theory in Biodiversity Sciences (Ulrich Brose)
• Spatial Interaction Ecology (Tiffany M. Knight)
In addition, there are several other units operating at iDiv: In the sDiv Synthesis Centre, scientists from all over the world come together in so-called working groups in order to gain new insight from existing knowledge and data. The aim of the graduate school, yDiv (Young BioDiversity Research Training Group) is to train a new generation of interdisciplinary biodiversity scientists. Scientific coordination promotes integration among the working groups and iDiv members who are located throughout Central Germany. IT Support, Bioinformatics (BIU) and Biodiversity Informatics (BDU) ensure the storage, provision and analysis of data. The administration team takes care of purchasing, finance, human resources and infrastructure. The Department of Media and Communication promotes dialogue with politics and society. | https://en.wikipedia.org/wiki/German_Centre_for_Integrative_Biodiversity_Research_(iDiv) |
The German Centre for Rail Traffic Research ( German : Deutsches Zentrum für Schienenverkehrsforschung (DZSF) ) is an independent, technical-scientific departmental research institution of the Federal Government. It was founded on May 23, 2019, and is located as an independent federal institute at the Eisenbahn-Bundesamt . [ 3 ] Its mission is to strengthen rail transport in Germany through application and solution-oriented research.
The budget for 2019 was 5 million euros and was expected to increase to 20 million euros in 2020. [ 4 ] 2020 staff should be built up first and the research content (along the federal research program) should be specified later. [ 5 ]
The coalition agreement for the 19th Election Period foresees a German Centre for Rail Transport Research (DZSF). This center should document research findings, manage and coordinate research projects, and also carry out research itself. This is intended to achieve a more effective use of resources and a lasting strengthening of railway traffic as a mode of transport.
The DZSF deals with the central issues of the railway sector as defined in the Federal Rail Research Program and provides solutions for them. Research fields are
The cross-cutting topics of digitalization , automation , migration, and legal issues are assigned to these three topic areas. These cross-cutting topics complement the integrative approach of the federal research program. | https://en.wikipedia.org/wiki/German_Centre_for_Rail_Traffic_Research |
The German Chemical Society ( German : Gesellschaft Deutscher Chemiker, GDCh ) is a learned society and professional association founded in 1949 to represent the interests of German chemists in local, national and international contexts. GDCh "brings together people working in chemistry and the molecular sciences and supports their striving for positive, sustainable scientific advance – for the good of humankind and the environment, and a future worth living for." [ 1 ]
The earliest precursor of today's GDCh was the German Chemical Society ( Deutsche Chemische Gesellschaft zu Berlin , DChG). Adolf von Baeyer was prominent among the German chemists who established DChG in 1867; and August Wilhelm von Hofmann was the first president. [ 1 ] This society was modeled after the British Chemical Society , which was the precursor of the Royal Society of Chemistry . Like its British counterpart, DChG sought to foster the communication of new ideas and facts throughout Germany and across international borders. [ 2 ]
In 1946, the current organization was created by a merger of the German Chemical Society (DChG) and the Association of German Chemists ( Verein Deutscher Chemiker , VDCh).
Honorary Members of the GDCh have included Otto Hahn , Robert B. Woodward , Jean-Marie Lehn , George Olah and other eminent scientists. [ 3 ]
Scientific publications of the society include Nachrichten aus der Chemie , [ 4 ] Angewandte Chemie , Chemistry: A European Journal , European Journal of Inorganic Chemistry , European Journal of Organic Chemistry , ChemPhysChem , ChemSusChem , ChemBioChem , ChemMedChem , ChemCatChem , ChemistryViews , Chemie Ingenieur Technik and Chemie in unserer Zeit . [ 5 ]
In the 21st century, the society has become a member of ChemPubSoc Europe , which is an organization of 16 European chemical societies. This European consortium was established in the late 1990s as many chemical journals owned by national chemical societies were amalgamated. [ 6 ]
The society acknowledges individual achievement with prizes and awards, including medals originally conferred by the predecessor organizations DChG and VDCh: | https://en.wikipedia.org/wiki/German_Chemical_Society |
The German Crystallographic Society ( Deutsche Gesellschaft für Kristallographie , or DGK in German) is a non-profit organization based in Berlin. As a voluntary association of scientists working in crystallography or interested in crystallography and other people and institutions, its goal is to promote crystallography in teaching, research and industrial practice as well as in the public, in particular by fostering the exchange of experience and ideas as well as further education at national and international level Frame. Working groups are dedicated to specific areas of crystallography. The Society has just over 1000 members.
The DGK represents crystallography in national and international scientific institutions. In particular, the DGK is a member body of the International Union of Crystallography (IUCr) and the European Crystallographic Association (ECA). The DGK nominates candidates for the crystallographically relevant review boards of the German Research Foundation . The association holds an annual conference every year, usually in spring.
The DGK issues a publication, the "Notifications", which is sent to the members annually.
Special scientific achievements are recognized with prizes, which are usually awarded annually. The DGK awards the following prizes: The Carl Hermann Medal for the scientific life's work of outstanding researchers in the field of crystallography and the Max von Laue Prize for young scientists. [ 3 ] [ 4 ] Furthermore, outstanding scientific contributions are honored with the Will Kleber commemorative coin. [ 5 ] The Waltrude and Friedrich Liebau Prize for promoting interdisciplinary crystallography is awarded by the DGK on behalf of the Waltrude and Friedrich Liebau Foundation. In addition, from 2022 the Lieselotte Templeton Prize is awarded for very good bachelor's, master's or similar theses in the field of crystallography. [ 6 ]
The DGK has provisionally applied to host the IUCr conference in Berlin in 2029 and was represented with its own stand at the corresponding conference in Prague in 2021. The IUCr conference was last represented in Germany in 1984, in Hamburg. [ 7 ]
In a blog on the DGK homepage, articles are written at irregular intervals with topics such as "studying during the corona pandemic", depositing crystal structure data sets in the ICSD database, reports on people or on past conferences.
The association was founded on March 12, 1991 in Munich by merging the scientific associations "Crystallography Working Group" (AGKr) and "Association for Crystallography" (VFK). The merger of the West German AGKr led by Wolfram Saenger with the VFK of the GDR led by Ursula Steinike (Berlin) was decided by a vote of the members of these societies. The first elected chairman of the German Crystallographic Society was Heinz Schulz.
President since inception:
The annual meeting of the DGK takes place at a different location (usually in Germany) every year. In 2020 the conference was organized together with the Polish Crystallographic Association in Wroclaw. In 2021 the conference was supposed to take place in Hamburg at DESY and in 2022 in Munich, but due to the corona pandemic they were held online. | https://en.wikipedia.org/wiki/German_Crystallographic_Society |
The German Emigrants Database is a research project [ 1 ] on European emigration to the United States of America . It is hosted by the Historisches Museum Bremerhaven . The database contains information about individuals who emigrated during the period of 1820-1939 mainly through German ports towards the United States. [ 2 ] [ 3 ] The aim of the GED is to make the collected data available to historical and social science research worldwide. Furthermore, the GED enables socio-statistical evaluations of emigrant data. In addition, the GED allows interested people to look for immigrant ancestors. The German Emigrants Database is financed by private donations and income generated by the database. Thus it receives no public subsidy. The revenues will be used entirely for the further expansion of the database. Legal and financial holder of the GED is the charitable “Association of Friends of the Historisches Museum Bremerhaven e.V.”
The data collected is based on the passenger manifests of the emigrant ships. [ 4 ] These lists had to be presented to the American immigration authorities upon arrival in the United States. Depending on the requirements of the U.S. immigration policy the detailedness of the data collected changed.
At the beginning of the 19th century 14 specific items of information were collected on the passenger manifests by the respective immigrants. At the beginning of the 20th century, already 40 specific items of information were collected. As a rule, age, sex, occupation, country of origin, name of the ship, departure, arrival ports and the arrival date were recorded in the United States. [ 5 ] In the German Emigrants Database the information of the passenger manifests is supplemented by other sources, such as certificates and civil registers. Since the 1980s, passenger lists are recorded electronically in the United States. One leader in data digitization was the "Center for Immigration Research" [ 6 ] at the University of Philadelphia / Pennsylvania. The German Emigrants Database has received its extensive overall data for the years 1850-1891 from the Center for Immigration Research. The GED accesses the electronic recording of the passenger lists provided by the National Archives of the USA since 1999. The GED has not yet been completed, but keeps on completing its data. [ 7 ] Currently, it contains the data of around 5 million emigrants. [ 8 ] This data covers the periods of 1820–1897, 1904 and 1907.
Since passenger manifests are hand-written forms, there are great discrepancies in quality. The readability can be affected by damage of the paper, illegible manuscripts, deletions or corrections. In addition, entries are sometimes not unique to a person. For example, some first and last names may occur several times.
Often, the information is based on verbal statements of the passengers. Thus, some typical mistakes that occurred due to misspelling or mishearing might still be part of the lists used.
Visitors to the Historisches Museum Bremerhaven have the possibility to conduct a personal research at two terminals in the museum's exhibition hall. It is also possible to issue a research contract for the GED. Online research in the GED is possible since 2007. [ 9 ] [ 10 ] This sort of research offered is grated by fees [ 11 ] depending on the emigrated person, family or group requested. Unless noted otherwise, the user receives a certificate to any person found with the traditional data of emigration, after the research is completed. | https://en.wikipedia.org/wiki/German_Emigrants_Database |
The German Future Prize award is considered one of the most prestigious conferred for science and innovation within Germany. The award is worth 250,000 euros [ 1 ] and is supported by numerous sponsors. [ 2 ]
This prize has been awarded to various exceptional individuals since 1997. [ 3 ] | https://en.wikipedia.org/wiki/German_Future_Prize |
The German Mineralogical Society ( Deutsche Mineralogische Gesellschaft , or DMG , in German) is a non-profit German society for the promotion of mineralogy . It has about 1400 members (2021) and belongs to the International Mineralogical Association and the umbrella organization for geosciences . It was founded at the meeting of German natural scientists and physicians in Cologne in 1908 based on a proposal by Friedrich Martin Berwerth at the 1907 meeting in Dresden .
The current chairman (2021-2022) is the geochemist Friedhelm von Blanckenburg .
The DMG has the sections:
Besides, the DMG has the working groups Archaeometry and Monument Preservation, Raw Materials Research, Mineralogical Museums and Collections and Mineralogy in Schools and Universities. [ 1 ]
The DMG awards prizes [ 2 ]
The DMG publishes multiple journals with other societies, including European Journal of Mineralogy [ 3 ] along with the Italian and French mineralogical societies, and the magazine Elements , [ 4 ] along with 18 other geochemical, cosmochemical and mineralogical societies. | https://en.wikipedia.org/wiki/German_Mineralogical_Society |
The 'German Network for Bioinformatics Infrastructure – de.NBI' is a national, academic and non-profit infrastructure initiated by the Federal Ministry of Education and Research funding 2015-2021. The network provides bioinformatics services to users in life sciences research and biomedicine in Germany and Europe. The partners organize training events, courses and summer schools on tools, standards and compute services provided by de.NBI to assist researchers to more effectively exploit their data. [ 2 ] From 2022, the network will be integrated into Forschungszentrum Jülich . [ 3 ]
In May 2013, the announcement of funding guidelines for a German Network for Bioinformatics Infrastructure (de.NBI) was published by the German Federal Ministry of Education and Research (BMBF). The aim of this announcement was to establish an infrastructure in Germany that will provide solutions to the ‘Big Data Problem’ in life science by means of bioinformatics services and training. A second announcement of funding guidelines for de.NBI partner projects was published in November 2015. The de.NBI program was launched by the BMBF in March 2015, and the partner projects started their work in November 2016. [ 2 ] In August 2016, Germany joined ELIXIR , the European life-sciences Infrastructure for biological Information, with the German ELIXIR Node (ELIXIR Germany) being run by de.NBI partners. [ 4 ] [ 5 ] [ 6 ]
The first coordinator of the de.NBI project was Alfred Pühler until 2021. The head of the German ELIXIR Node is Andreas Tauch. [ 7 ]
The de.NBI network consists of the eight interconnected centers and one coordination unit including 40 research, service and infrastructure groups with about 250 bioinformaticians involved. [ 8 ] In addition, it is possible to apply for an associated partnership as Service and Training Partner or as Training Partner within de.NBI.
The de.NBI network is open for further partners which like to take part in the network. These partners are called Associated Partners and are divided into two groups: Associated Service and Training Partners or Associated Training Partners. Associated Service und Training Partners offer at least one service and training course while Associated Training Partners only provide at least one training course to the de.NBI network. As of February 2020 the de.NBI network has six Associated Service and Training Partners ( University of Kiel , University of Jena , DKFZ , EMBL Heidelberg, RKI Werningerode, ZB MED , Heidelberg University , Federal Institute for Materials Research and Testing ) and two Associated Training Partners ( University Medical Center Hamburg-Eppendorf , University of Tübingen ). These partners cover topics in Metabolomics , Phylogenetics , human bioinformatics, eukaryotic genomics, metaproteomics, NGS , 16S rRNA amplicon and single-cell analysis as well as the general IT topics Linux and scripting languages .
The de.NBI network offers a large portfolio of resources for the German and international life science community. It mainly includes databases, bioinformatics tools and hardware based on a federated cloud system.
de.NBI develops and maintains the five large databases SILVA , [ 10 ] PANGAEA , [ 11 ] BacDive , [ 12 ] ProteinsPlus [ 13 ] and BRENDA . [ 14 ] They provide access to ribosomal RNA genes from all three domains of life (SILVA), georeferenced data from earth system research (PANGAEA), strain-linked information on the different aspects of bacterial and archaeal biodiversity (BacDive), protein structures (ProteinPlus) and to comprehensive enzyme information (BRENDA).
de.NBI develops and supplies about 100 bioinformatics tools for the German and global life sciences community, e.g. Galaxy (computational biology) /useGalaxy.eu (Workflow engine for all Freiburg RNA Tools), [ 15 ] EDGAR (Comparative Genome Analyses Plattform), [ 16 ] KNIME (Workflow engine), [ 17 ] OpenMS (Open-source software C++ library for LC/MS data management and analyses), [ 18 ] SeqAN (Open source C++ library of efficient algorithms and data structures), [ 19 ] PIA (toolbox for MS based protein inference and identification analysis), [ 9 ] Fiji (software) (Image processing package), MetFrag (in silico fragmenter combines compound database searching and fragmentation prediction for small molecule identification from tandem mass spectrometry data), [ 20 ] COPASI ( open source software application for creating and solving mathematical models of biological processes ), [ 21 ] SIAMCAT (Framework for the statistical inference of associations between microbial communities and host phenotypes ), e!DAL - PGP (Open source software framework to publish and share research data), MGX ( Metagenome analysis), [ 22 ] ASA³P (automated WGS analysis of bacterial cohorts), [ 23 ] Bakta [ 24 ] (annotation of bacterial genomes and plasmids) and many more.
de.NBI tools are also registered and searchable in the ELIXIR Tools and Data Services Registry that provides more information in a standardized format.
de.NBI develops and maintains a cloud system (de.NBI cloud) started in 2016. [ 25 ] It is a collaboration project between the universities of Bielefeld, Freiburg, Gießen, Heidelberg and Tübingen. The whole system is accessible through a single sign-on (SSO) via the central de.NBI Cloud Portal and is based on the ELIXIR Authentication and authorization infrastructure (ELIXIR AAI). The de.NBI cloud comprises more than 56,000 computing cores and 80 petabytes of storage capacity (as of November 2021).
Different types of training activities are supported and organized by de.NBI. First of all, the summer schools provide training courses for undergraduate and graduate students in specific topics related to one or several de.NBI centers. The respective centers organize tool-specific training. These trainings are attached to existing conferences or organized independently. In addition, online training was introduced on the de.NBI website in 2016. Since 2017, online training formats like hackathons or webinars are offered by all service centers.
The de.NBI training program started in 2015 with 17 f2f training courses with 329 participants, steadily increasing to 79 courses with 1586 Participants in 2019. In 2020 and 2021, the practical delivery of training was significantly affected by the COVID-19 pandemic, but the development of online training and materials (40 courses with 1,149 participants in 2020) enabled 2,128 training participants to be upskilled in 49 courses in 2021. A total of 9,076 scientists have been trained in 371 courses through our bioinformatics network to date (as of January 2022). [ 26 ]
Next to the training courses de.NBI offers annual summer schools to cover a distinct topic in more detail. The first Summer School was held in 2015 by the Service Centers Bielefeld-Gießen (BiGi) Center for Microbial Bioinformatics, RBC and de.NBI-SysBio and was focused in the workflow from genome assembly to genome and transcriptome analysis. [ 27 ] In the following years the Summer Schools were organized by the Service Centers BioInfraProt, CIBI and BiGi as well as BioData, GCBN and de.NBI-SysBio and held at different locations throughout Germany. The Summer Schools covered the topics proteomics and mass spectrometry data (2016), [ 28 ] Cloud Computing for Bioinformatics (2017), [ 29 ] Computational genomics and RNA biology (2017), [ 30 ] Metabolomics (2018), [ 31 ] Research Data Management (2018) [ 32 ] and (Bio)Data Science (2019). [ 33 ] Two de.NBI Summer Schools took place in 2021. 1) Analysis of mass spectrometry data in proteomics, lipidomics and Metabolomics organized by BioInfra.Prot, CIBI and de.NBI-SysBio, [ 34 ] 2) Microbial Community Analysis organized by BiGi and HD-HuB. [ 35 ]
In addition, as an outreach activity de.NBI supported the Summer School BioByte 2019 at University of Halle addressed at high school students which offers an ideal opportunity to get to know the diversity of bioinformatics. [ 36 ] | https://en.wikipedia.org/wiki/German_Network_for_Bioinformatics_Infrastructure |
German Society for Aeronautics and Astronautics ( DGLR ; German : Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. ) is a German aerospace society . It was founded in 1912 under the name of Wissenschaftliche Gesellschaft für Flugtechnik (WGF). It is the second oldest technical and scientific society in aerospace in the world. [ 1 ]
The German Society for Aeronautics and Astronautics (Deutsche Gesellschaft für Luft- und Raumfahrt; DGLR) is the oldest institution in Germany to offer a common forum for those with a private or professional interest in aeronautics and spaceflight . The Society offers a network for knowledge exchange about the aerospace sector; current projects and developments are presented, and good ideas are nurtured and rewarded.
DGLR is the only technical and scientific association for aviation and spaceflight in Germany. Its members represent industry, government, education and research institutions. It acts as a link between every discipline and hence encourages a comprehensive exchange of information and experience. Beyond its function as a provider of information for its members, DGLR acts as a representative of aeronautics and spaceflight for the general public – nationally and internationally.
DGLR combines varying areas of expertise and specialist committees into a network of skill sets. Here, members can pursue their individual areas of interest and connect with like-minded people. Regional groups offer the option of networking at a local level. At events, members have the opportunity to network and catch up on recent developments. For example, every year the German Aerospace Conference (Deutsche Luft- und Raumfahrtkongress; DLRK) acts as a central national forum for aeronautics and spaceflight.
Encouragement of new talent in science and technology is a core objective of DGLR. Through the Skyfuture online information portal, it offers contacts and guidance in training, study and career options in the aerospace sector. DGLR also helps student trainee groups carry out their own projects at universities. [ 2 ]
The society was founded in Berlin on April 3, 1912 under the name Wissenschaftliche Gesellschaft für Flugtechnik e. V. (WGF) . This makes it the world's second oldest technical and scientific society for aviation and aerospace. The society already had 300 members in its first year.
In 1914, the WGF was renamed Wissenschaftliche Gesellschaft für Luftfahrt (WGL) . Ludwig Prandtl , who was already involved in the founding of the society, was commissioned to set up scientific and technical committees, e.g. for engines , aerodynamics , aerology , etc., which can still be found in the structure of the society today.
By 1929, the number of members had risen to over 800, and important aviation scientists such as Junkers , Oberth and Dornier gave lectures at annual general meetings. As early as 1928, the first lectures on space travel and rocket flight were added. In 1936, the WGL was dissolved and its members became part of the newly founded Lilienthalgesellschaft für Luftfahrtforschung .
From 1945 to 1952, all aviation activities were banned in Germany. It was not until April 21, 1952 that the Wissenschaftliche Gesellschaft für Luftfahrt was re-established. The society's highest award was the Ludwig-Prandtl-Ring , which was awarded to national and international scientists, thus establishing and strengthening relations with foreign societies and helping the WGL to gain international recognition.
In 1962, the WGL was renamed the Wissenschaftliche Gesellschaft für Luft- und Raumfahrt e. V. (WGLR - Scientific Society for Aeronautics and Astronautics) in order to cover all future problems of the emerging space travel and technology.
At the same time, from 1923 onwards, the space travel movement developed in Germany, triggered by publications by the physicist and later rocket pioneer Hermann Oberth . The Verein für Raumschifffahrt e. V. was founded and established the first German rocket airfield in Berlin in 1932. The association was dissolved in 1934 and the Gesellschaft für Weltraumforschung e. V. , Berlin (GfW) was founded. Hermann Oberth was honorary president of the GfW from 1948, which was renamed Deutsche Gesellschaft für Raketentechnik und Raumfahrt e. V. (DGRR) in 1956.
In 1967 it was decided that the DGRR and the WGLR should be represented in one association in future. This led to the merger of the two associations to form the German Society for Aeronautics and Astronautics (DGLR) .
From 1990, negotiations began to merge the DGLR with the Hermann-Oberth-Gesellschaft (HOG) , the Gesellschaft für Weltraumforschung und Raumfahrt (GWR) and the Fachverband Luftfahrt (FL) into one society. Thus, 1993, the German Society for Aeronautics and Astronautics - Lilienthal-Oberth e. V. (DGLR) was founded. [ 3 ]
The members of the DGLR have the opportunity to actively shape the affairs of the Society. They can participate in the annual general meeting, vote on important issues and help decide who is elected to the DGLR Senate. The Senate in turn elects the Presidium, which ultimately appoints the Secretary General of the DGLR office. Since 2019, there is also a Young Senate, which represents DGLR’s young members. Their main task is to recruit and promote new young members and support their networking within the DGLR.
Regionally, members can join and shape those DGLR district groups that are responsible for their region in Germany. Within the district groups, a leader and their deputies are elected by the group’s members for three years. The district groups not only promote the aims of the Society but also strengthen its internal and regional cohesion.
The DGLR is divided into expert committees in the fields of aeronautics , space and cross-cutting issues that provide information on perspective development directions in the different areas of aerospace. In symposia, seminars, lectures and workshops organised by the expert committees, they provide relevant and current information on the aeronautics and space sector.
One of DGLR's core tasks is to promote young professionals. To this end, it brings together young, committed and inquisitive people and enables them to network with potential employers. Young researchers at universities, colleges, universities of applied sciences and other institutions are also promoted in the form of student trainee groups – scientific research groups of students who permanently work together on aerospace-related projects. [ 4 ]
The DGLR has been organizing the German Aerospace Congress (DLRK - Deutscher Luft- und Raumfahrtkongress) every year since 1952. It serves as a platform for the exchange of experience among current and future experts in the field of aerospace. The DLRK has been established as a networking event in the aerospace industry for decades and welcomes around 1000 participants every year. [ 5 ]
The DGLR also participates in many other national and international aerospace events and organizes smaller events at district level.
Persons interested in aerospace can register as full members and thus benefit from the services of the society. Industrial companies, associations, clubs and other organizations active or involved in aerospace can become corporate members of the DGLR.
The DGLR itself is a voting member of the International Astronautical Federation (IAF) and the International Council of the Aeronautical Sciences (ICAS) . It is one of the four founding members of the Council of European Aerospace Societies (CEAS) and has been working with the American Institute of Aeronautics and Astronautics (AIAA) for many years. [ 6 ]
The following awards are given out by DGLR for outstanding contributions: [ 7 ]
This article about an organisation based in Germany is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/German_Society_for_Aeronautics_and_Astronautics |
The German Society for Stem Cell Research ( Deutsche Gesellschaft für Stammzellforschung or GSZ ), established in 2003 by Juergen Hescheler, brings scientists from around Germany together and has an emphasis on basic research in stem cell biology . The main purpose of the society is to promote stem cell research. In order to achieve this goal the society promotes the stem cell research in basic research and in academic teaching by allocating available funds to support training programs, to organize seminars and conferences, as well as instigating the exchange of students and scientists on national and international level for collaborative projects and resulting publications. The German Society for Stem Cell Research aims at establishing a network of scientists in stem cell research nationwide and eventually offering a platform to provide competent and independent counsel for all questions related to stem cell research.
In 2003 scientists from around Germany initiated the establishment of the German Society for Stem Cell Research with emphasis on basic research in stem cell biology. The society is a non-profit organisation , financially and politically autonomous , and is registered with the district court Cologne under the number VR 14639 since November 4, 2004. Juergen Hescheler is the chairman of the organisation.
The main purpose of the society is to promote stem cell research. In order to achieve this goal the society will promote the stem cell research in basic research and in academic teaching by allocating available funds to support training programs, to organize seminars and conferences, as well as instigating the exchange of students and scientists on the national and international level for collaborative projects and resulting publications.
The German Society for Stem Cell Research aims at establishing a network of scientists in stem cell research nationwide, and eventually bringing them under a single platform and making a competent and independent counsel for all questions related to stem cell research.
The Journal of Stem Cells & Regenerative Medicine is the official journal of the society. [ 1 ] | https://en.wikipedia.org/wiki/German_Society_for_Stem_Cell_Research |
In the statistical theory of estimation , the German tank problem consists of estimating the maximum of a discrete uniform distribution from sampling without replacement . In simple terms, suppose there exists an unknown number of items which are sequentially numbered from 1 to N . A random sample of these items is taken and their sequence numbers observed; the problem is to estimate N from these observed numbers.
The problem can be approached using either frequentist inference or Bayesian inference , leading to different results. Estimating the population maximum based on a single sample yields divergent results, whereas estimation based on multiple samples is a practical estimation question whose answer is simple (especially in the frequentist setting) but not obvious (especially in the Bayesian setting).
The problem is named after its historical application by Allied forces in World War II to the estimation of the monthly rate of German tank production from very limited data. This exploited the manufacturing practice of assigning and attaching ascending sequences of serial numbers to tank components (chassis, gearbox, engine, wheels), with some of the tanks eventually being captured in battle by Allied forces.
The adversary is presumed to have manufactured a series of tanks marked with consecutive whole numbers, beginning with serial number 1. Additionally, regardless of a tank's date of manufacture, history of service, or the serial number it bears, the distribution over serial numbers becoming revealed to analysis is uniform, up to the point in time when the analysis is conducted.
Assuming tanks are assigned sequential serial numbers starting with 1, suppose that four tanks are captured and that they have the serial numbers: 19, 40, 42 and 60.
A frequentist approach (using the minimum-variance unbiased estimator ) predicts the total number of tanks produced will be:
A Bayesian approach (using a uniform prior over the integers in [ 4 , Ω ] {\displaystyle [4,\Omega ]} for any suitably large Ω {\displaystyle \Omega } ) predicts that the median number of tanks produced will be very similar to the frequentist prediction:
whereas the Bayesian mean predicts that the number of tanks produced would be:
Let N equal the total number of tanks predicted to have been produced, m equal the highest serial number observed and k equal the number of tanks captured.
The frequentist prediction is calculated as:
The Bayesian median is calculated as:
The Bayesian mean is calculated as:
These Bayesian quantities are derived from the Bayesian posterior distribution:
This probability mass function has a positive skewness , related to the fact that there are at least 60 tanks. Because of this skewness, the mean may not be the most meaningful estimate. The median in this example is 74.5, in close agreement with the frequentist formula. Using Stirling's approximation , the posterior may be approximated by an exponentially decaying function of n ,
which results in the following approximation for the median:
and the following approximations for the mean and standard deviation:
During the course of the Second World War, the Western Allies made sustained efforts to determine the extent of German production and approached this in two major ways: conventional intelligence gathering and statistical estimation. In many cases, statistical analysis substantially improved on conventional intelligence. In some cases, conventional intelligence was used in conjunction with statistical methods, as was the case in estimation of Panther tank production just prior to D-Day .
The allied command structure had thought the Panzer V (Panther) tanks seen in Italy, with their high velocity, long-barreled 75 mm/L70 guns, were unusual heavy tanks and would only be seen in northern France in small numbers, much the same way as the Tiger I was seen in Tunisia. The US Army was confident that the Sherman tank would continue to perform well, as it had versus the Panzer III and Panzer IV tanks in North Africa and Sicily. [ a ] Shortly before D-Day, rumors indicated that large numbers of Panzer V tanks were being used.
To determine whether this was true, the Allies attempted to estimate the number of tanks being produced. To do this, they used the serial numbers on captured or destroyed tanks. The principal numbers used were gearbox numbers, as these fell in two unbroken sequences. Chassis and engine numbers were also used, though their use was more complicated. Various other components were used to cross-check the analysis. Similar analyses were done on wheels, which were observed to be sequentially numbered (i.e., 1, 2, 3, ..., N ). [ 2 ] [ b ] [ 3 ] [ 4 ]
The analysis of tank wheels yielded an estimate for the number of wheel molds that were in use. A discussion with British road wheel makers then estimated the number of wheels that could be produced from this many molds, which yielded the number of tanks that were being produced each month. Analysis of wheels from two tanks (32 road wheels each, 64 road wheels total) yielded an estimate of 270 tanks produced in February 1944, substantially more than had previously been suspected. [ 5 ]
German records after the war showed production for the month of February 1944 was 276. [ 6 ] [ c ] The statistical approach proved to be far more accurate than conventional intelligence methods, and the phrase "German tank problem" became accepted as a descriptor for this type of statistical analysis.
Estimating production was not the only use of this serial-number analysis. It was also used to understand German production more generally, including number of factories, relative importance of factories, length of supply chain (based on lag between production and use), changes in production, and use of resources such as rubber.
According to conventional Allied intelligence estimates, the Germans were producing around 1,400 tanks a month between June 1940 and September 1942. Applying the formula below to the serial numbers of captured tanks, the number was calculated to be 246 a month. After the war, captured German production figures from the ministry of Albert Speer showed the actual number to be 245. [ 3 ]
Estimates for some specific months are given as: [ 7 ]
Similar serial-number analysis was used for other military equipment during World War II, most successfully for the V-2 rocket. [ 8 ]
Factory markings on Soviet military equipment were analyzed during the Korean War , and by German intelligence during World War II. [ 9 ]
In the 1980s, some Americans were given access to the production line of Israel's Merkava tanks. The production numbers were classified, but the tanks had serial numbers, allowing estimation of production. [ 10 ]
The formula has been used in non-military contexts, for example to estimate the number of Commodore 64 computers built, where the result (12.5 million) matches the low-end estimates. [ 11 ]
To confound serial-number analysis, serial numbers can be excluded, or usable auxiliary information reduced. Alternatively, serial numbers that resist cryptanalysis can be used, most effectively by randomly choosing numbers without replacement from a list that is much larger than the number of objects produced, or by producing random numbers and checking them against the list of already assigned numbers; collisions are likely to occur unless the number of digits possible is more than twice the number of digits in the number of objects produced; this is valid for serial numbers in any base (see: Birthday problem ) . [ d ] For this, a cryptographically secure pseudorandom number generator may be used. All these methods require a lookup table (or breaking the cypher) to back out from serial number to production order, which complicates use of serial numbers: a range of serial numbers cannot be recalled, for instance, but each must be looked up individually, or a list generated.
Alternatively, sequential serial numbers can be encrypted with a simple substitution cipher , which allows easy decoding, but is also easily broken by frequency analysis : even if starting from an arbitrary point, the plaintext has a pattern (namely, numbers are in sequence). One example is given in Ken Follett 's novel Code to Zero , where the encryption of the Jupiter-C rocket serial numbers is given by:
The code word here is Huntsville (with repeated letters omitted) to get a 10-letter key. [ 12 ] The rocket number 13 was therefore "HN", and the rocket number 24 was "UT".
For point estimation (estimating a single value for the total, N ^ {\displaystyle {\widehat {N}}} ), the minimum-variance unbiased estimator (MVUE, or UMVU estimator) is given by: [ e ]
where m is the largest serial number observed ( sample maximum ) and k is the number of tanks observed ( sample size ). [ 10 ] [ 13 ] Note that once a serial number has been observed, it is no longer in the pool and will not be observed again.
This has a variance [ 10 ]
so the standard deviation is approximately N / k , the expected size of the gap between sorted observations in the sample.
The formula may be understood intuitively as the sample maximum plus the average gap between observations in the sample, the sample maximum being chosen as the initial estimator, due to being the maximum likelihood estimator , [ f ] with the gap being added to compensate for the negative bias of the sample maximum as an estimator for the population maximum, [ g ] and written as
This can be visualized by imagining that the observations in the sample are evenly spaced throughout the range, with additional observations just outside the range at 0 and N + 1. If starting with an initial gap between 0 and the lowest observation in the sample (the sample minimum), the average gap between consecutive observations in the sample is ( m − k ) / k {\displaystyle (m-k)/k} , the − k {\displaystyle -k} being because the observations themselves are not counted in computing the gap between observations. [ h ] A derivation of the expected value and the variance of the sample maximum are shown in the page of the discrete uniform distribution .
This philosophy is formalized and generalized in the method of maximum spacing estimation ; a similar heuristic is used for plotting position in a Q–Q plot , plotting sample points at k / ( n + 1) , which is evenly on the uniform distribution, with a gap at the end.
Instead of, or in addition to, point estimation, interval estimation can be carried out, such as confidence intervals .
These are easily computed, based on the observation that the probability that k observations in the sample will fall in an interval covering p of the range (0 ≤ p ≤ 1) is p k (assuming in this section that draws are with replacement, to simplify computations; if draws are without replacement, this overstates the likelihood, and intervals will be overly conservative).
Thus the sampling distribution of the quantile of the sample maximum is the graph x 1/ k from 0 to 1: the p -th to q -th quantile of the sample maximum m are the interval [ p 1/ k N , q 1/ k N ]. Inverting this yields the corresponding confidence interval for the population maximum of [ m / q 1/ k , m / p 1/ k ].
For example, taking the symmetric 95% interval p = 2.5% and q = 97.5% for k = 5 yields 0.025 1/5 ≈ 0.48, 0.975 1/5 ≈ 0.995, so the confidence interval is approximately [1.005 m , 2.08 m ]. The lower bound is very close to m , thus more informative is the asymmetric confidence interval from p = 5% to 100%; for k = 5 this yields 0.05 1/5 ≈ 0.55 and the interval [ m , 1.82 m ].
More generally, the (downward biased) 95% confidence interval is [ m , m /0.05 1/ k ] = [ m , m ·20 1/k ]. For a range of k values, with the UMVU point estimator (plus 1 for legibility) for reference, this yields:
Immediate observations are:
Note that m / k cannot be used naively (or rather ( m + m / k − 1)/ k ) as an estimate of the standard error SE , as the standard error of an estimator is based on the population maximum (a parameter), and using an estimate to estimate the error in that very estimate is circular reasoning .
The Bayesian approach to the German tank problem [ 14 ] is to consider the posterior probability ( N = n ∣ M = m , K = k ) {\displaystyle (N=n\mid M=m,K=k)} that the number of enemy tanks N {\displaystyle N} is n {\displaystyle n} , when the number of observed tanks K {\displaystyle K} is k {\displaystyle k} , and the maximum observed serial number M {\displaystyle M} is m {\displaystyle m} .
The answer to this problem depends on the choice of prior for N {\displaystyle N} . One can proceed using a proper prior over the positive integers, e.g., the Poisson or Negative Binomial distribution, where a closed formula for the posterior mean and posterior variance can be obtained. [ 15 ] Below, we will instead adopt a bounded uniform prior.
For brevity, in what follows, ( N = n ∣ M = m , K = k ) {\displaystyle (N=n\mid M=m,K=k)} is written ( n ∣ m , k ) {\displaystyle (n\mid m,k)} .
The rule for conditional probability gives
The expression
is the conditional probability that the maximum serial number observed, M {\displaystyle M} , is equal to m {\displaystyle m} , when the number of enemy tanks, N {\displaystyle N} , is known to be equal to n {\displaystyle n} , and the number of enemy tanks observed, K {\displaystyle K} , is known to be equal to k {\displaystyle k} .
It is
where ( n k ) {\displaystyle {\binom {n}{k}}} is a binomial coefficient and [ k ≤ n ] {\displaystyle [k\leq n]} is an Iverson bracket .
The expression can be derived as follows: ( m ∣ n , k ) {\displaystyle (m\mid n,k)} answers the question: "What is the probability of a specific serial number m {\displaystyle m} being the highest number observed in a sample of k {\displaystyle k} tanks, given there are n {\displaystyle n} tanks in total?"
One can think of the sample of size k {\displaystyle k} to be the result of k {\displaystyle k} individual draws without replacement. Assume m {\displaystyle m} is observed on draw number d {\displaystyle d} . The probability of this occurring is: m − 1 n ⋅ m − 2 n − 1 ⋅ m − 3 n − 2 ⋯ m − d + 1 n − d + 2 ⏟ d − 1 times ⋅ 1 n − d + 1 ⏟ draw no. d ⋅ m − d n − d ⋅ m − d − 1 n − d − 1 ⋯ m − d − ( k − d − 1 ) n − d − ( k − d − 1 ) ⏟ k − d times = ( n − k ) ! n ! ⋅ ( m − 1 ) ! ( m − k ) ! . {\displaystyle \underbrace {{\frac {m-1}{n}}\cdot {\frac {m-2}{n-1}}\cdot {\frac {m-3}{n-2}}\cdots {\frac {m-d+1}{n-d+2}}} _{d-1{\text{ times}}}\cdot \underbrace {\frac {1}{n-d+1}} _{{\text{draw no. }}d}\cdot \underbrace {{\frac {m-d}{n-d}}\cdot {\frac {m-d-1}{n-d-1}}\cdots {\frac {m-d-(k-d-1)}{n-d-(k-d-1)}}} _{k-d{\text{ times}}}={\frac {(n-k)!}{n!}}\cdot {\frac {(m-1)!}{(m-k)!}}.}
As can be seen from the right-hand side, this expression is independent of d {\displaystyle d} and therefore the same for each d ≤ k {\displaystyle d\leq k} . As m {\displaystyle m} can be drawn on k {\displaystyle k} different draws, the probability of any specific m {\displaystyle m} being the largest one observed is k {\displaystyle k} times the above probability: ( m ∣ n , k ) = k ⋅ ( n − k ) ! n ! ⋅ ( m − 1 ) ! ( m − k ) ! = ( m − 1 k − 1 ) ( n k ) − 1 . {\displaystyle (m\mid n,k)=k\cdot {\frac {(n-k)!}{n!}}\cdot {\frac {(m-1)!}{(m-k)!}}={\binom {m-1}{k-1}}{\binom {n}{k}}^{-1}.}
The expression ( m ∣ k ) = ( M = m ∣ K = k ) {\displaystyle (m\mid k)=(M=m\mid K=k)} is the probability that the maximum serial number is equal to m {\displaystyle m} once k {\displaystyle k} tanks have been observed but before the serial numbers have actually been observed.
The expression ( m ∣ k ) {\displaystyle (m\mid k)} can be re-written in terms of the other quantities by marginalizing over all possible n {\displaystyle n} .
We assume that k {\displaystyle k} is fixed in advance so that we do not have to consider any distribution over k {\displaystyle k} . Thus, our prior can depend on k {\displaystyle k} .
The expression
is the credibility that the total number of tanks, N {\displaystyle N} , is equal to n {\displaystyle n} when the number K {\displaystyle K} tanks observed is known to be k {\displaystyle k} , but before the serial numbers have been observed. Assume that it is some discrete uniform distribution
The upper limit Ω {\displaystyle \Omega } must be finite, because the function
is not a mass distribution function. Our result below will not depend on Ω {\displaystyle \Omega } .
Provided that Ω > m {\displaystyle \Omega >m} , so that the prior is consistent with the observed data:
As Ω → ∞ {\displaystyle \Omega \rightarrow \infty } , the summation approaches ∑ n = m ∞ ( m ∣ n , k ) {\displaystyle \sum _{n=m}^{\infty }(m\mid n,k)} (which is finite if k ≥ 2). Thus, for suitably large Ω {\displaystyle \Omega } , we have
For k ≥ 1 the mode of the distribution of the number of enemy tanks is m .
For k ≥ 2, the credibility that the number of enemy tanks is equal to n {\displaystyle n} , is
The credibility that the number of enemy tanks, N , is greater than n , is
For k ≥ 3, N has the finite mean value :
For k ≥ 4, N has the finite standard deviation :
These formulas are derived below.
The following binomial coefficient identity is used below for simplifying series relating to the German Tank Problem.
This sum formula is somewhat analogous to the integral formula
These formulas apply for k > 1.
Observing one tank randomly out of a population of n tanks gives the serial number m with probability 1/ n for m ≤ n , and zero probability for m > n . Using Iverson bracket notation this is written
This is the conditional probability mass distribution function of m {\displaystyle m} .
When considered a function of n for fixed m this is a likelihood function.
The maximum likelihood estimate for the total number of tanks is N 0 = m , clearly a biased estimate since the true number can be more than this, potentially many more, but cannot be fewer.
The marginal likelihood (i.e. marginalized over all models) is infinite , being a tail of the harmonic series .
but
where H n {\displaystyle H_{n}} is the harmonic number .
The credibility mass distribution function depends on the prior limit Ω {\displaystyle \Omega } :
The mean value of N {\displaystyle N} is
If two tanks rather than one are observed, then the probability that the larger of the observed two serial numbers is equal to m , is
When considered a function of n for fixed m this is a likelihood function
The total likelihood is
and the credibility mass distribution function is
The median N ~ {\displaystyle {\tilde {N}}} satisfies
so
and so the median is
but the mean value of N {\displaystyle N} is infinite
The conditional probability that the largest of k observations taken from the serial numbers {1,..., n }, is equal to m , is
The likelihood function of n is the same expression
The total likelihood is finite for k ≥ 2:
The credibility mass distribution function is
The complementary cumulative distribution function is the credibility that N > x
The cumulative distribution function is the credibility that N ≤ x
The order of magnitude of the number of enemy tanks is
The statistical uncertainty is the standard deviation σ {\displaystyle \sigma } , satisfying the equation
So
and
The variance-to-mean ratio is simply | https://en.wikipedia.org/wiki/German_tank_problem |
Germane is the chemical compound with the formula Ge H 4 , and the germanium analogue of methane . It is the simplest germanium hydride and one of the most useful compounds of germanium. Like the related compounds silane and methane, germane is tetrahedral . It burns in air to produce GeO 2 and water . Germane is a group 14 hydride .
Germane has been detected in the atmosphere of Jupiter . [ 3 ]
Germane is typically prepared by reduction of germanium oxides, notably germanates , with hydride reagents such as sodium borohydride , potassium borohydride , lithium borohydride , lithium aluminium hydride , sodium aluminium hydride . The reaction with borohydrides is catalyzed by various acids and can be carried out in either aqueous or organic solvent . On laboratory scale, germane can be prepared by the reaction of Ge(IV) compounds with these hydride reagents. [ 4 ] [ 5 ] A typical synthesis involved the reaction of sodium germanate with potassium borohydride . [ 6 ]
Other methods for the synthesis of germane include electrochemical reduction and a plasma -based method. [ 7 ] The electrochemical reduction method involves applying voltage to a germanium metal cathode immersed in an aqueous electrolyte solution and an anode counter-electrode composed of a metal such as molybdenum or cadmium . In this method, germane and hydrogen gases evolve from the cathode while the anode reacts to form solid molybdenum oxide or cadmium oxides . The plasma synthesis method involves bombarding germanium metal with hydrogen atoms (H) that are generated using a high frequency plasma source to produce germane and digermane .
Germane is weakly acidic . In liquid ammonia GeH 4 is ionised forming NH 4 + and GeH 3 − . [ 8 ] With alkali metals in liquid ammonia GeH 4 reacts to give white crystalline MGeH 3 compounds. The potassium (potassium germyl or potassium trihydrogen germanide KGeH 3 ) and rubidium compounds (rubidium germyl or rubidium trihydrogen germanide RbGeH 3 ) have the sodium chloride structure implying a free rotation of the trihydrogen germanide anion GeH 3 − , the caesium compound, caesium germyl or caesium trihydrogen germanide CsGeH 3 in contrast has the distorted sodium chloride structure of TlI . [ 8 ]
The gas decomposes near 600K (327°C; 620°F) to germanium and hydrogen. Because of its thermal lability , germane is used in the semiconductor industry for the epitaxial growth of germanium by MOVPE or chemical beam epitaxy . [ 9 ] Organogermanium precursors (e.g. isobutylgermane , alkylgermanium trichlorides, and dimethylaminogermanium trichloride) have been examined as less hazardous liquid alternatives to germane for deposition of Ge-containing films by MOVPE. [ 10 ]
Germane is a highly flammable , potentially pyrophoric , [ 11 ] and a highly toxic gas. In 1970, the American Conference of Governmental Industrial Hygienists (ACGIH) published the latest changes and set the occupational exposure threshold limit value at 0.2 ppm for an 8-hour time weighted average. [ 12 ] The LC50 for rats at 1 hour of exposure is 622 ppm. [ 13 ] Inhalation or exposure may result in malaise, headache, dizziness, fainting, dyspnea, nausea, vomiting, kidney injury, and hemolytic effects. [ 14 ] [ 15 ] [ 16 ]
The US Department of Transportation hazard class is 2.3 Poisonous Gas. [ 12 ] | https://en.wikipedia.org/wiki/Germane |
Germanene is a material made up of a single layer of germanium atoms. [ 2 ] The material is created in a process similar to that of silicene and graphene , in which high vacuum and high temperature are used to deposit a layer of germanium atoms on a substrate. [ 2 ] [ 3 ] [ 4 ] High-quality thin films of germanene have revealed unusual two-dimensional structures with novel electronic properties suitable for semiconductor device applications and materials science research.
In September 2014, G. Le Lay and others reported the deposition of a single atom thickness, ordered and two-dimensional multi-phase film by molecular beam epitaxy upon a gold surface in a crystal lattice with Miller indices (111). The structure was confirmed with scanning tunneling microscopy (STM) revealing a nearly flat honeycomb structure. [ 5 ]
We have provided compelling evidence of the birth of nearly flat germanene—a novel, synthetic germanium allotrope which does not exist in nature. It is a new cousin of graphene.
Additional confirmation was obtained by spectroscopic measurement and density functional theory calculations. The development of high quality and nearly flat single atom films created speculation that germanene may replace graphene if not merely add an alternative to the novel properties of related nanomaterials. [ 2 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ]
Bampoulis and others [ 10 ] have reported the formation of germanene on the outermost layer of Ge 2 Pt nanocrystals. Atomically resolved STM images of germanene on Ge 2 Pt nanocrystals reveal a buckled honeycomb structure. This honeycomb lattice is composed of two hexagonal sublattices displaced by 0.2 Å in the vertical direction with respect to each other. The nearest-neighbor distance was found to be 2.5±0.1 Å, in close agreement with the Ge-Ge distance in germanene.
Based on STM observations and density functional theory calculations, formation of an apparently more distorted form of germanene has been reported on platinum . [ 5 ] [ 11 ] Epitaxial growth of germanene crystals on GaAs (0001) has also been demonstrated, and calculations suggest that the minimal interactions should allow germanene to be readily removed from this substrate. [ 12 ]
Germanene's structure is described as "a group-IV graphene-like two-dimensional buckled nanosheet". [ 13 ] Adsorption of additional germanium onto the graphene-like sheet leads to formation of " dumbbell " units, each with two out-of-plane atoms of germanium, one on either side of the plane. Dumbbells attract each other. Periodically repeating arrangements of dumbbell structures may lead to additional stable phases of germanene, with altered electronic and magnetic properties. [ 14 ]
In October 2018, Junji Yuhara and others reported that germanene is easily prepared by a segregation method, using a bare Ag thin film on a Ge substrate and achieved in situ its epitaxial growth. [ 15 ] The growth of germanene, akin to graphene and silicene, by a segregation method, is considered to be technically very important for the easy synthesis and transfer of this highly promising 2D electronic material.
Germanene's electronic and optical properties have been determined from ab initio calculations, [ 16 ] and structural and electronic properties from first principles. [ 17 ] [ 18 ] These properties make the material suitable for use in the channel of a high-performance field-effect transistor [ 19 ] and have generated discussion regarding the use of elemental monolayers in other electronic devices. [ 20 ] The electronic properties of germanene are unusual, and provide a rare opportunity to test the properties of Dirac fermions . [ 21 ] [ 22 ] Germanene has no band gap , but attaching a hydrogen atom to each germanium atom creates one. [ 23 ] These unusual properties are generally shared by graphene , silicene , germanene, stanene , and plumbene . [ 22 ] [ 24 ] [ 25 ] [ 26 ] | https://en.wikipedia.org/wiki/Germanene |
The germanium-vacancy center ( Ge-V ) is an optically active defect in diamond , which can be created by doping germanium into diamond during its growth or by implanting germanium ions into diamond after its growth. Its properties are similar to those of the silicon-vacancy center in diamond (SiV). Ge-V can behave as a single-photon source and shows potential for quantum and nanoscience applications due to its narrow zero-phonon line (ZPL) and minimal phononic-sideband (compared to that of the nitrogen-vacancy center (NV)). [ 1 ]
Ge-V is predicted to consist of one germanium atom situated between two adjacent lattice vacancies and have the same D 3d point group symmetry as SiV. It has a single ZPL at 602 nm (2.059 eV) at room-temperature, which splits into two components separated by 0.67 meV at low-temperatures (10 K). The Ge-V has an excited state lifetime of 1.4–5.5 ns. [ 1 ]
Ge-V can be created during the diamond growth, or by ion implantation and subsequent annealing at 800 °C. The former way results in lower lattice strain, as revealed by the spread in the position and width of the Ge-V ZPL. [ 1 ] [ 2 ] | https://en.wikipedia.org/wiki/Germanium-vacancy_center_in_diamond |
A germicidal lamp (also known as disinfection lamp or sterilizer lamp ) is an electric light that produces ultraviolet C (UVC) light. This short-wave ultraviolet light disrupts DNA base pairing , causing formation of pyrimidine dimers , and leads to the inactivation of bacteria , viruses , and protozoans . It can also be used to produce ozone for water disinfection . They are used in ultraviolet germicidal irradiation (UVGI).
There are four common types available:
Low-pressure mercury lamps are very similar to a fluorescent lamp , with a wavelength of 253.7 nm (1182.5 THz).
The most common form of germicidal lamp looks similar to an ordinary fluorescent lamp but the tube contains no fluorescent phosphor . In addition, rather than being made of ordinary borosilicate glass , the tube is made of fused quartz or vycor 7913 [ 1 ] glass. These two changes combine to allow the 253.7 nm ultraviolet light produced by the mercury arc to pass out of the lamp unmodified (whereas, in common fluorescent lamps, it causes the phosphor to fluoresce , producing visible light ). Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.
An older design looks like an incandescent lamp but with the envelope containing a few droplets of mercury. In this design, the incandescent filament heats the mercury, producing a vapor which eventually allows an arc to be struck, short circuiting the incandescent filament.
As with all gas-discharge lamps , low- and high-pressure mercury lamps exhibit negative resistance and require the use of an external ballast to regulate the current flow. The older lamps that resembled an incandescent lamp were often operated in series with an ordinary 40 W incandescent "appliance" lamp; the incandescent lamp acted as the ballast for the germicidal lamp.
High-pressure lamps are much more similar to HID lamps than fluorescent lamps.
These lamps radiate a broad-band UVC radiation, rather than a single line. They are widely used in industrial water treatment, because they are very intense radiation sources. High-pressure lamps produce very bright bluish white light.
Excimer lamps emit narrow-band UVC and vacuum-ultraviolet radiation at a variety of wavelengths depending on the medium. They are mercury-free and reach full output quicker than a mercury lamp, and generate less heat. Excimer emission at 207 and 222 nm appears to be safer than traditional 254 nm germicidal radiation, due to greatly reduced penetration of these wavelengths in human skin.
Recent developments in light-emitting diode (LED) technology have led to the commercial availability of UVC LED sources.
UVC LEDs use semiconductor materials to produce light in a solid-state device. The wavelength of emission is tuneable by adjusting the chemistry of the semiconductor material, giving a selectivity to the emission profile of the LED across, and beyond, the germicidal wavelength band. Advances in understanding and synthesis of the AlGaN materials system led to significant increases in the output power, device lifetime, and efficiency of UVC LEDs in the early 2010s.
The reduced size of LEDs opens up options for small reactor systems allowing point-of-use applications and integration into medical devices. [ 2 ] Low power consumption of semiconductors introduce UV disinfection systems that utilized small solar cells in remote or Third World applications. [ 2 ]
By 2019, LEDs made up 41.4% of UV light sales, up from 19.2% in 2014 [ 3 ] The UV-C LED global market is expected to rise from $223m in 2017 to US$991m in 2023. [ 4 ]
Germicidal lamps are used to sterilize workspaces and tools used in biology laboratories and medical facilities. If the quartz envelope transmits shorter wavelengths, such as the 185 nm mercury emission line, they can also be used wherever ozone is desired, for example, in the sanitizing systems of hot tubs and aquariums . They are also used by geologists to provoke fluorescence in mineral samples, aiding in their identification. In this application, the light produced by the lamp is usually filtered to remove as much visible light as possible, leaving just the UV light. Germicidal lamps are also used in waste water treatment in order to kill microorganisms.
The light produced by germicidal lamps is also used to erase EPROMs ; the ultraviolet photons are sufficiently energetic to allow the electrons trapped on the transistors' floating gates to tunnel through the gate insulation, eventually removing the stored charge that represents binary ones and zeroes.
For most purposes, ozone production would be a detrimental side effect of lamp operation. To prevent this, most germicidal lamps are treated to absorb the 185 nm mercury emission line (which is the longest wavelength of mercury light which will ionize oxygen).
In some cases (such as water sanitization), ozone production is precisely the point. This requires specialized lamps which do not have the surface treatment.
Short-wave UV light is harmful to humans. In addition to causing sunburn and (over time) skin cancer , this light can produce extremely painful inflammation of the cornea of the eye, which may lead to temporary or permanent vision impairment . For this reason, the light produced by a germicidal lamp must be carefully shielded against direct viewing, with consideration of reflections and dispersed light. A February 2017 risk analysis of UVC lights concluded that ultraviolet light from these lamps can cause skin and eye problems. [ 5 ] | https://en.wikipedia.org/wiki/Germicidal_lamp |
In biology and genetics , the germline is the population of a multicellular organism 's cells that develop into germ cells . In other words, they are the cells that form gametes ( eggs and sperm ), which can come together to form a zygote . They differentiate in the gonads from primordial germ cells into gametogonia , which develop into gametocytes , which develop into the final gametes. [ 1 ] This process is known as gametogenesis .
Germ cells pass on genetic material through the process of sexual reproduction. This includes fertilization , recombination and meiosis . These processes help to increase genetic diversity in offspring. [ 2 ]
Certain organisms reproduce asexually via processes such as apomixis , parthenogenesis , autogamy , and cloning . [ 3 ] [ 4 ] Apomixis and Parthenogenesis both refer to the development of an embryo without fertilization. The former typically occurs in plants seeds, while the latter tends to be seen in nematodes, as well as certain species of reptiles, birds, and fish. [ 5 ] [ 6 ] Autogamy is a term used to describe self pollination in plants. [ 7 ] Cloning is a technique used to creation of genetically identical cells or organisms. [ 8 ]
In sexually reproducing organisms, cells that are not in the germline are called somatic cells . According to this definition, mutations , recombinations and other genetic changes in the germline may be passed to offspring, but changes in a somatic cell will not be. [ 9 ] This need not apply to somatically reproducing organisms, such as some Porifera [ 10 ] and many plants. For example, many varieties of citrus , [ 11 ] plants in the Rosaceae and some in the Asteraceae , such as Taraxacum , produce seeds apomictically when somatic diploid cells displace the ovule or early embryo. [ 12 ]
In an earlier stage of genetic thinking, there was a clear distinction between germline and somatic cells. For example, August Weismann proposed and pointed out, a germline cell is immortal in the sense that it is part of a lineage that has reproduced indefinitely since the beginning of life and, barring accident, could continue doing so indefinitely. [ 13 ] However, it is now known in some detail that this distinction between somatic and germ cells is partly artificial and depends on particular circumstances and internal cellular mechanisms such as telomeres and controls such as the selective application of telomerase in germ cells, stem cells and the like. [ 14 ]
Not all multicellular organisms differentiate into somatic and germ lines, [ 15 ] but in the absence of specialised technical human intervention practically all but the simplest multicellular structures do so. In such organisms somatic cells tend to be practically totipotent , and for over a century sponge cells have been known to reassemble into new sponges after having been separated by forcing them through a sieve. [ 10 ]
Germline can refer to a lineage of cells spanning many generations of individuals—for example, the germline that links any living individual to the hypothetical last universal common ancestor , from which all plants and animals descend .
Plants and basal metazoans such as sponges (Porifera) and corals (Anthozoa) do not sequester a distinct germline, generating gametes from multipotent stem cell lineages that also give rise to ordinary somatic tissues. It is therefore likely that germline sequestration first evolved in complex animals with sophisticated body plans, i.e. bilaterians. There are several theories on the origin of the strict germline-soma distinction. Setting aside an isolated germ cell population early in embryogenesis might promote cooperation between the somatic cells of a complex multicellular organism. [ 16 ] Another recent theory suggests that early germline sequestration evolved to limit the accumulation of deleterious mutations in mitochondrial genes in complex organisms with high energy requirements and fast mitochondrial mutation rates. [ 15 ]
Reactive oxygen species (ROS) are produced as byproducts of metabolism. In germline cells, ROS are likely a significant cause of DNA damages that, upon DNA replication , lead to mutations . 8-Oxoguanine , an oxidized derivative of guanine , is produced by spontaneous oxidation in the germline cells of mice, and during the cell's DNA replication cause GC to TA transversion mutations. [ 17 ] Such mutations occur throughout the mouse chromosomes as well as during different stages of gametogenesis .
The mutation frequencies for cells in different stages of gametogenesis are about 5 to 10-fold lower than in somatic cells both for spermatogenesis [ 18 ] and oogenesis . [ 19 ] The lower frequencies of mutation in germline cells compared to somatic cells appears to be due to more efficient DNA repair of DNA damages, particularly homologous recombinational repair, during germline meiosis . [ 20 ] Among humans, about five percent of live-born offspring have a genetic disorder, and of these, about 20% are due to newly arisen germline mutations . [ 18 ]
Epigenetic alterations of DNA include modifications that affect gene expression, but are not caused by changes in the sequence of bases in DNA. A well-studied example of such an alteration is the methylation of DNA cytosine to form 5-methylcytosine . This usually occurs in the DNA sequence CpG , changing the DNA at the CpG site from CpG to 5-mCpG. Methylation of cytosines in CpG sites in promoter regions of genes can reduce or silence gene expression. [ 21 ] About 28 million CpG dinucleotides occur in the human genome, [ 22 ] and about 24 million CpG sites in the mouse genome (which is 86% as large as the human genome [ 23 ] ). In most tissues of mammals, on average, 70% to 80% of CpG cytosines are methylated (forming 5-mCpG). [ 24 ]
In the mouse, by days 6.25 to 7.25 after fertilization of an egg by a sperm, cells in the embryo are set aside as primordial germ cells (PGCs). These PGCs will later give rise to germline sperm cells or egg cells. At this point the PGCs have high typical levels of methylation. Then primordial germ cells of the mouse undergo genome-wide DNA demethylation , followed by subsequent new methylation to reset the epigenome in order to form an egg or sperm. [ 25 ]
In the mouse, PGCs undergo DNA demethylation in two phases. The first phase, starting at about embryonic day 8.5, occurs during PGC proliferation and migration, and it results in genome-wide loss of methylation, involving almost all genomic sequences. This loss of methylation occurs through passive demethylation due to repression of the major components of the methylation machinery. [ 25 ] The second phase occurs during embryonic days 9.5 to 13.5 and causes demethylation of most remaining specific loci, including germline-specific and meiosis-specific genes. This second phase of demethylation is mediated by the TET enzymes TET1 and TET2, which carry out the first step in demethylation by converting 5-mC to 5-hydroxymethylcytosine (5-hmC) during embryonic days 9.5 to 10.5. This is likely followed by replication-dependent dilution during embryonic days 11.5 to 13.5. [ 26 ] At embryonic day 13.5, PGC genomes display the lowest level of global DNA methylation of all cells in the life cycle. [ 25 ]
In the mouse, the great majority of differentially expressed genes in PGCs from embryonic day 9.5 to 13.5, when most genes are demethylated, are upregulated in both male and female PGCs. [ 26 ]
Following erasure of DNA methylation marks in mouse PGCs, male and female germ cells undergo new methylation at different time points during gametogenesis. While undergoing mitotic expansion in the developing gonad, the male germline starts the re-methylation process by embryonic day 14.5. The sperm-specific methylation pattern is maintained during mitotic expansion. DNA methylation levels in primary oocytes before birth remain low, and re-methylation occurs after birth in the oocyte growth phase. [ 25 ] | https://en.wikipedia.org/wiki/Germline |
In developmental biology , the cells that give rise to the gametes are often set aside during embryonic cleavage . During development, these cells will differentiate into primordial germ cells , migrate to the location of the gonad , and form the germline of the animal.
Cleavage in most animals segregates cells containing germ plasm from other cells. The germ plasm effectively turns off gene expression to render the genome of the cell inert. Cells expressing germ plasm become primordial germ cells (PGCs) which will then give rise to the gametes . The germ line development in mammals, on the other hand, occurs by induction and not by an endogenous germ plasm (see reference 6.).
Germ plasm has been studied in detail in Drosophila. The posterior pole of the embryo contains necessary materials for the fertility of the fly. This cytoplasm, pole plasm, contains specialized materials called polar granules and the pole cells are the precursors to primordial germ cells. [ citation needed ]
Pole plasm is organized by and contains the proteins and mRNA of the posterior group genes (such as oskar , nanos gene , Tudor, vasa, and Valois). These genes play a role in germ line development to localize nanos mRNA to the posterior and localize germ cell determinants. Drosophila progeny with mutations in these genes fail to produce pole cells and are thus sterile, giving these mutations the name 'grandchildless'. The genes oskar , nanos and germ cell-less (gcl) have important roles. Oskar is sufficient to recruit the other genes to form functional germ plasm. Nanos is required to prevent mitosis and somatic differentiation and for the pole cells to migrate to function as PGCs (see next section). Gcl is necessary (but not sufficient) for pole cell formation. In addition to these genes, Pgc polar granule component blocks phosphorylation and consequently activation of RNA polymerase II and shuts down transcription. [ citation needed ]
Similar germ plasm has been identified in Amphibians in the polar cytoplasm at the vegetal pole. This cytoplasm moves to the bottom of the blastocoel and eventually ends up as its own subset of endodermal cells. While specified to produce germ cells, the germ plasm does not irreversibly commit these cells to produce gametes and no other cell type. [ 1 ] [ 2 ]
The first phase of migration in Drosophila occurs when the pole cells move passively and infold into the midgut invagination. Active migration occurs through repellents and attractants. The expression of wunen in the endoderm repels the PGCs out. The expression of columbus and hedgehog attracts the PGCs to the mesodermal precursors of the gonad. Nanos is required during migration. Regardless of PGC injection site, PGCs are able to correctly migrate to their target sites. [ citation needed ]
In zebrafish, the PGCs express two CXCR4 transmembrane receptor proteins. The signaling system involving this protein and its ligand, Sdf1, is necessary and sufficient to direct PGC migration in fish.
In frogs, the PGCs migrate along the mesentery to the gonadal mesoderm facilitated by orientated extracellular matrix with fibronectin. There is also evidence for the CXCR4/Sdf1 system in frogs. [ citation needed ]
In birds, the PGCs arise from the epiblast and migrate to anteriorly of the primitive streak to the germinal crest. From there, they use blood vessels to find their way to the gonad. The CXCR4/Sdf1 system is also used, though may not be the only method necessary. [ 3 ]
In the mouse, primordial germ cells (PGCs) arise in the posterior primitive streak of the embryo [ 4 ] and start to migrate around 6.25 days after conception. PGCs start to migrate to the embryonic endoderm and then to the hindgut and finally towards the future genital ridges where the somatic gonadal precursors reside. [ 4 ] [ 5 ] This migration requires a series of attractant and repellent cues as well as a number of adhesion molecules such as E-cadherin and β1-Integrin to guide the migration of PGCs. [ 4 ] Around 10 days post conception; the PGCs occupy the genital ridge [ 5 ] where they begin to lose their motility and polarized shape. [ 4 ]
Mammalian PGCs are specified by signalling between cells (induction), rather than by the segregation of germ plasm as the embryo divides. [ 6 ] In mice, PGCs originate from the proximal epiblast, close to the extra-embryonic ectoderm (ExE), of the post-implantation embryo as early as embryonic day 6.5. [ 7 ] By E7.5 a founding population of approximately 40 PGCs are generated in this region of the epiblast in the developing mouse embryo. [ 8 ] [ 9 ] [ 10 ] The epiblast, however, also give rise to somatic cell lineages that make up the embryo proper; including the endoderm, ectoderm and mesoderm. [ 11 ] [ 12 ] [ 13 ] The specification of primordial germ cells in mammals is mainly attributed to the downstream functions of two signaling pathways; the BMP signaling pathway and the canonical WNT/β-catenin pathway . [ 7 ]
Bone morphogenetic protein 4 (BMP4) is released by the extra-embryonic ectoderm (ExE) at embryonic day 5.5 to 5.75 directly adjacent to the epiblast [ 6 ] and causes the region of the epiblast nearest to the ExE to express Blimp1 and Prdm14 in a dose-dependent manner. [ 14 ] This is evident as the number of PGCs forming in the epiblast decreases in proportion to the loss of BMP4 alleles. [ 15 ] BMP4 acts through its downstream intercellular transcription factors SMAD1 and SMAD5. [ 15 ] [ 16 ] [ 17 ] [ 18 ] [ 19 ] During approximately the same time, WNT3 starts to be expressed in the posterior visceral endoderm of the epiblast. [ 20 ] [ 21 ] WNT3 signalling has been shown to be essential in order for the epiblast to acquire responsiveness to the BMP4 signal from the ExE. [ 22 ] WNT3 mutants fail to establish a primordial germ cell population, but this can be restored with exogenous WNT activity. [ 23 ] The WNT3/β-catenin signalling pathway is essential for the expression of the transcription factor T (Brachyury), a transcription factor that was previously characterized somatic and mesoderm specific genes. [ 24 ] [ 25 ] T was recently found to be both necessary and sufficient to induce the expression of the known PGC specification genes Blimp1 and Prdm14. [ 23 ] The induction of Transcription Factor T was seen 12 hours after BMP/WNT signaling, as opposed to the 24 to 36 hours it took for Blimp1 and Prdm14 genes to be expressed. Transcription factor T acts upstream of BLIMP1 and Prdm14 in PGC specification by binding to the genes respective enhancer elements. [ 23 ] It is important to note that while T can activate the expression of Blimp1 and Prdm14 in the absence of both BMP4 and WNT3, pre-exposure of PGC progenitors to WNTs (without BMP4) prevents T from activating these genes. [ 23 ] Details on how BMP4 prevents T from inducing mesodermal genes, and only activate PGC specification genes, remain unclear.
Expression of Blimp1 is the earliest known marker of PGC specification. [ 26 ] A mutation in the Blimp1 gene results in the formation of PGC-like cells at embryonic day 8.5 that closely resemble their neighbouring somatic cells. [ 27 ] A central role of Blimp 1 is the induction of Tcfap2c, a helix-span helix transcription factor. [ 28 ] Tcfap2c mutants exhibited an early loss of primordial germ cells. [ 29 ] [ 30 ] Tcfap2c is thought to repress somatic gene expression, including the mesodermal marker Hoxb1. [ 30 ] So, Blimp1, Tcfap2c and Prdm14 together are able to activate and repress the transcription of all the necessary genes to regulate PGC specification. [ 14 ] Mutation of Prdm14 results in the formation of PGCs that are lost by embryonic day 11.5. [ 31 ] The loss of PGCs in the Prdm14 mutant is due to failure in global erasure of histone 3 methylation patterns. [ 32 ] Blimp1 and Prdm14 also elicit another epigenetic event that causes global DNA demethylation. [ 33 ]
Other notable genes positively regulated by Blimp1 and Prdm14 are: Sox2 , Nanos3, Nanog , Stella and Fragilis. [ 14 ] At the same time, Blimp1 and Prdm14 also repress the transcription of programs that drive somatic differentiation by inhibiting transcription of the Hox family genes . [ 14 ] In this way, Blimp1 and Prdm14 drive PGC specification by promoting germ line development and potential pluripotency transcriptional programs while also keeping the cells from taking on a somatic fate. [ 14 ]
With the vast knowledge about in-vivo PGC specification collected over the last few decades, several attempts to generate in-vitro PGCs from post-implantation epiblast were made. Various groups were able to successfully generate PGC-like cells, cultured in the presence of BMP4 and various cytokines. [ 15 ] The efficiency of this process was later enhanced by the addition of stem cell factor (SCF), epidermal growth factor (EGF), leukaemia inhibitory factor (LIF) and BMP8B. [ 34 ] PGC-like cells generated using this method can be transplanted into a gonad, where the differentiate, and are able to give viable gametes and offspring in vivo. [ 34 ] PGC-like cells can also be generated from naïve embryonic stem cells (ESCs) that are cultured for two days in the presence of FGF and Activin-A to adopt an epiblast-like state. These cells are then cultured with BMP4, BMP8B, EGF, LIF and SCF and various cytokines for four more days. [ 35 ] These in-vitro generated PGCs can also develop into viable gametes and offspring. [ 35 ]
Prior to their arrival at the gonads, PGCs express pluripotency factors, generate pluripotent cell lines in cell culture (known as EG cells , [ 36 ] [ 37 ] ) and can produce multi-lineage tumors, known as teratomas . [ 38 ] Similar findings in other vertebrates indicate that PGCs are not yet irreversibly committed to produce gametes, and no other cell type. [ 1 ] [ 39 ] [ 40 ] On arrival at the gonads, human and mouse PGCs activate widely conserved germ cell-specific factors, and subsequently down-regulate the expression of pluripotency factors. [ 41 ] This transition results in the determination of germ cells, a form of cell commitment that is no longer reversible. [ 42 ]
Prior to their occupation of the genital ridge, there is no known difference between XX and XY PGCs. [ 4 ] However, once migration is complete and germ cell determination has occurred, these germline cells begin to differentiate according to the gonadal niche.
Male PGCs become known as gonocytes once they cease migration and undergo mitosis. [ 43 ] The term gonocyte is generally used to describe all stages post PGC until the gonocytes differentiate into spermatogonia. [ 43 ] Anatomically, gonocytes can be identified as large, euchromatic cells that often have two nucleoli in the nucleus. [ 43 ]
In the male genital ridge, transient Sry expression causes supporting cells to differentiate into Sertoli cells which then act as the organizing center for testis differentiation. Point mutations or deletions in the human or mouse Sry coding region can lead to female development in XY individuals. [ 44 ] Sertoli cells also act to prevent gonocytes from differentiating prematurely. [ 45 ] They produce the enzyme CYP26B1 to counteract surrounding retinoic acid . Retinoic acid acts as a signal to the gonocytes to enter meiosis . [ 45 ] The gonocyte and Sertoli cells have been shown to form gap and desmosomelike junctions as well as adherins junctions composed of cadherins and connexins . [ 43 ] To differentiate into spermatogonia, the gonocytes must lose their junctions to Sertoli cells and become migratory once again. [ 43 ] They migrate to the basement membrane of the seminiferous cord [ 43 ] and differentiate.
In the gonads, the germ cells undergo either spermatogenesis or oogenesis depending on whether the sex is male or female respectively. [ citation needed ]
Mitotic germ stem cells, spermatogonia , divide by mitosis to produce spermatocytes committed to meiosis. The spermatocytes divide by meiosis to form spermatids . The post-meiotic spermatids differentiate through spermiogenesis to become mature and functional spermatozoa . [ citation needed ] Spermatogenic cells at different stages of development in the mouse have a frequency of mutation that is 5 to 10-fold lower than the mutation frequency in somatic cells . [ 46 ]
In Drosophila , the ability of premeiotic male germ line cells to repair double-strand breaks declines dramatically with age. [ 47 ] In mouse, spermatogenesis declines with advancing paternal age likely due to an increased frequency of meiotic errors. [ 48 ]
Mitotic germ stem cells, oogonia , divide by mitosis to produce primary oocytes committed to meiosis. Unlike sperm production, oocyte production is not continuous. These primary oocytes begin meiosis but pause in diplotene of meiosis I while in the embryo. All of the oogonia and many primary oocytes die before birth. After puberty in primates, small groups of oocytes and follicles prepare for ovulation by advancing to metaphase II. Only after fertilization is meiosis completed. Meiosis is asymmetric producing polar bodies and oocytes with large amounts of material for embryonic development. [ citation needed ] The mutation frequency of female mouse germ line cells, like male germ line cells, is also lower than that of somatic cells. [ 49 ] Low germ line mutation frequency appears to be due, in part, to elevated levels of DNA repair enzymes that remove potentially mutagenic DNA damages . Enhanced genetic integrity may be a fundamental characteristic of germ line development. [ 49 ] | https://en.wikipedia.org/wiki/Germline_development |
Germline mosaicism , also called gonadal mosaicism , is a type of genetic mosaicism where more than one set of genetic information is found specifically within the gamete cells; conversely, somatic mosaicism is a type of genetic mosaicism found in somatic cells . Germline mosaicism can be present at the same time as somatic mosaicism or individually, depending on when the conditions occur. Pure germline mosaicism refers to mosaicism found exclusively in the gametes and not in any somatic cells. Germline mosaicism can be caused either by a mutation that occurs after conception, [ 1 ] [ 2 ] or by epigenetic regulation , [ 3 ] alterations to DNA such as methylation that do not involve changes in the DNA coding sequence.
A mutation in an allele acquired by a somatic cell early in its development can be passed on to its daughter cells, including those that later specialize to gametes. With such mutation within the gamete cells, a pair of medically typical individuals may have repeated succession of children who suffer from certain genetic disorders such as Duchenne muscular dystrophy and osteogenesis imperfecta because of germline mosaicism. It is possible for parents unaffected by germline mutations to produce an offspring with an autosomal dominant (AD) disorder due to a random new mutation within one’s gamete cells known as sporadic mutation ; however, if these parents produce more than one child with an AD disorder, germline mosaicism is more likely the cause than a sporadic mutation. [ 4 ] [ unreliable source? ] In the first documented case of its kind, two offspring of a French woman who had no phenotypic expression of the AD disorder hypertrophic cardiomyopathy , inherited the disease. [ 5 ]
Germline mosaicism disorders are usually inherited in a pattern that suggests that the condition is dominant in either or both of the parents. That said, diverging from Mendelian gene inheritance patterns, a parent with a recessive allele can produce offspring expressing the phenotype as dominant through germline mosaicism. A situation may also arise in which the parents have milder phenotypic expression of a mutation yet produce offspring with more expressive phenotypic variance and a more frequent sibling recurrences of the mutation. [ 6 ] [ 7 ] [ 8 ]
Diseases caused by germline mosaicism can be difficult to diagnose as genetically-inherited because the mutant alleles are not likely to be present in the somatic cells. Somatic cells are more commonly used for genetic analysis because they are easier to obtain than gametes. If the disease is a result of pure germline mosaicism, then the disease causing mutant allele would never be present in the somatic cells. This is a source of uncertainty for genetic counselling . An individual may still be a carrier for a certain disease even if the disease causing mutant allele is not present in the cells that were analyzed because the causative mutation could still exist in some of the individual's gametes. [ 9 ]
Germline mosaicism may contribute to the inheritance of many genetic conditions. Conditions that are inherited by means of germline mosaicism are often mistaken as being the result of de novo mutations . Various diseases are now being re-examined for presence of mutant alleles in the germline of the parents in order to further our understanding of how they can be passed on. [ 10 ] The frequency of germline mosaicism is not known due to the sporadic nature of the mutations causing it and the difficulty in obtaining the gametes that must be tested to diagnose it.
Autosomal dominant or X-linked familial disorders often prompt prenatal testing for germline mosaicism. This diagnosis may involve minimally invasive procedures, such as blood sampling or amniotic fluid sampling. [ 9 ] [ 11 ] [ 12 ] [ 13 ] [ 14 ] Collected samples can be sequenced via common DNA testing methods, such as Sanger Sequencing , MLPA , or Southern Blot analysis, to look for variations on relevant genes connected to the disorder. [ 14 ] [ 15 ]
The recurrence rate of conditions caused by germline mosaicism varies greatly between subjects. Recurrence is proportional to the number of gamete cells that carry the particular mutation with the condition. If the mutation occurred earlier on in the development of the gamete cells, then the recurrence rate would be higher because a greater number of cells would carry the mutant allele. [ 11 ]
A Moroccan family consisting of two healthy unrelated parents and three offspring—including two with Noonan syndrome, a rare autosomal dominant disorder with varying expression and genetic heterogeneity—underwent genetic testing revealing that both of the siblings with NS share the same PTPN11 haplotype from both parents, while a distinct paternal and maternal haplotype was inherited by the unaffected sibling. [ 16 ] In the paper Germline and somatic mosaicism in transgenic mice published in 1986, Thomas M.Wilkie, Ralph L.Brinster, and Richard D.Palmiter analyzed a germline mosaicism experiment done on 262 transgenic mice and concluded that 30% of founder transgenic mice are mosaic in the germline. [ 17 ] | https://en.wikipedia.org/wiki/Germline_mosaicism |
Germplasm refers to genetic resources such as seeds, tissues, and DNA sequences that are maintained for the purpose of animal and plant breeding , conservation efforts, agriculture, and other research uses. These resources may take the form of seed collections stored in seed banks , trees growing in nurseries, animal breeding lines maintained in animal breeding programs or gene banks . Germplasm collections can range from collections of wild species to elite, domesticated breeding lines that have undergone extensive human selection. Germplasm collection is important for the maintenance of biological diversity, food security, and conservation efforts.
In the United States, germplasm resources are regulated by the National Genetic Resources Program (NGRP), created by the U.S. congress in 1990. In addition the web server The Germplasm Resources Information Network (GRIN) [ 1 ] provides information about germplasms as they pertain to agriculture production. [ 2 ]
In the United States, germplasm resources are regulated by the National Genetic Resources Program (NGRP), created by the U.S. congress in 1990. In addition the web server The Germplasm Resources Information Network (GRIN) provides information about germplasms as they pertain to agriculture production.
Specifically for plants, there is the U.S. National Plant Germplasm System (NPGS) which holds > 450,000 accessions with 10,000 species of the 85 most commonly grown crops. Many accessions held are international species, and NPGS distributes germplasm resources internationally. [ 3 ]
As genetic information moves largely online there is a transition in germplasm information from a physical location (seed banks, cryopreserving) to online platforms containing genetic sequences. In addition there are issues in the collection germplasm information and where they are shared. Historically some germplasm information had been collected in developing countries and then shared to researchers who then sell the donor country the original germplasm that they altered. There is a lack of compensation to the donor countries and this is an issue. [ 3 ]
Effective Germplasm work includes the collection, storage, analysis, documentation, and exchange of genetic information. This information can be stored as accessions , which is DNA sequence information, or live cells/tissues that can be preserved. However, only about 5% of current germplasm resources are living samples. [ 4 ] For live cells/tissues, germplasm resources can be stored ex situ in seed banks , botanic gardens , or through cryopreservation . Cryopreservation is the process of storing germplasm at very low temperatures, such as liquid nitrogen. [ 5 ] This process ensures that cells do not degrade and keeps the germplasm intact. In addition, resources can be stored in situ such as the natural area the species was found.
About 10,000 years ago is when humans began to domesticate plant species for the purpose of food, seeds, and vegetation. [ 4 ] Since then, agriculture has been a staple for human civilizations and plant breeding has allowed more genetic diversity and a more diverse gene pool. [ 4 ] Germplasm resources allow for more genetic assets to be used and integrated for agricultural systems for plant breeding and bringing about new varieties. In addition, researchers are looking at crop wild relatives (CWRs) that could expand gene pools of crop species and provide more ability to select target traits.
Furthermore, we are currently facing a biodiversity crisis event that is caused by human activities and industrialization. Many plants and animals have gone extinct due to losing their habitat, their habitat being degraded with contaminants, and climate change . Germplasm resources are a way to conserve the pre-existing biological diversity and to possibly regenerate habitats. By storing this genetic information there is data about what species are present including plants, animals, bacteria, and fungi and what a complete ecosystem in specific areas look like. | https://en.wikipedia.org/wiki/Germplasm |
Germs: Biological Weapons and America's Secret War is a 2001 book written by New York Times journalists Judith Miller , Stephen Engelberg, and William Broad . [ 1 ] It describes how humanity has dealt with biological weapons , and the dangers of bioterrorism . It was the 2001 New York Times #1 Non-Fiction Bestseller the weeks of October 28 and November 4. [ 2 ]
Germs , is a work of investigative journalism employing biographical and historical narrative to provide context. [ 3 ] The three authors interviewed hundreds of scientists and senior U.S. officials, and reviewed recently declassified documents, and reports from the former Soviet Union 's bioweapons laboratories.
" Germs were always what I call the Caboose of the weapons of mass destruction train." (Judith Miller, November 18, 2001)
The book opens with an account of the 1984 salmonella poisonings in The Dalles, Oregon , caused by followers of Bhagwan Shree Rajneesh who sprayed salmonella onto salad bars. Other research shows how Moscow scientists created an untraceable germ that would induce the body to self-destruct, and reveals that the U.S. military planned for germ warfare on Cuba during the 1960s. [ 1 ] Three classified U.S. biodefense projects are detailed: Project Bacchus , Project Clear Vision , and Project Jefferson . [ 5 ] Germs concludes with an assessment of the United States' ability to deter future bio-attack. [ 6 ]
The New York Times Book Review was favorable, though it criticized the book's tone as "somewhat alarmist ". [ 3 ] BusinessWeek was also generally favorable, except for pointing out some conflicting views on bioterrorism. [ 6 ] The Guardian ' s book review by British psychiatrist Simon Wessely , cautioned against panic , stating that biological weapons can cause destruction through fear, effectively giving the biodefense industry "the equivalent of a blank cheque ". [ 7 ]
On November 13, 2001, the science TV series Nova aired an episode entitled Bioterror . Two years in the making, it chronicled Miller, Engelberg, and Broad's research and investigation into biological weapons. [ 8 ] | https://en.wikipedia.org/wiki/Germs:_Biological_Weapons_and_America's_Secret_War |
Gernot Frenking (born January 23, 1946, in Körbecke) is a German chemist known for his contribution in theoretical chemistry . [ 1 ]
From 1960 to 1964, Frenking initially trained as a chemical laboratory assistant at the Bayer AG paint factory in Uerdingen . He completed his Abitur on the second educational path and studied chemistry at the RWTH Aachen from 1969 to 1973. In 1973 he received his diploma at the RWTH Aachen with Hans-Dieter Scharf with a thesis on calculations of chemical reactivity using quantum theoretical models as well as measurements and theoretical calculations on the dipole moments of some compounds. [ 2 ]
From 1973 to 1976, Frenking was a DAAD fellow in Japan with Kenichi Fukui at Kyoto University , where he worked on frontier orbital theory . In Japan, Frenking was also one of the first scholarship holders of the Japan Society for the Promotion of Science (JSPS), the largest Japanese research funding society. From 1976 to 1979 he was a doctoral student at the Institute for Organic Chemistry at Technische Universität Berlin , where he received his doctorate in 1979. From 1977 to 1982 he was an assistant at the TU Berlin with teaching duties. Between 1979 and 1984 he researched with Helmut Schwarz for his habilitation in the field of theoretical organic chemistry and habilitated with a thesis on MO-SCF investigations on the structure and reactivity of molecules in the gas phase. From 1982 to 1984 he worked at TU Berlin with a Liebig scholarship from the Chemical Industry Fund. Frenking went to the Stanford Research Institute (SRI International) on the American west coast as a postdoc. There, with Gilda Loew , he researched structure-activity relationships of biologically active compounds, in particular opiates , in theoretical investigations until 1988 and carried out conformational investigations using molecular mechanics calculations of pharmaceutically interesting compounds. [ 1 ]
After returning to Germany, he was briefly a scientist at the Collaborative Research Center 260 in the Chemistry Department of the University of Marburg . In 1990, Frenking was appointed C3 professor for computer applications in chemistry at the University of Marburg, and in 1998 he became C4 professor for theoretical chemistry there. | https://en.wikipedia.org/wiki/Gernot_Frenking |
In the theory of causal structure on Lorentzian manifolds , Geroch's theorem or Geroch's splitting theorem (first proved by Robert Geroch ) gives a topological characterization of globally hyperbolic spacetimes.
A Cauchy surface can possess corners, and thereby need not be a differentiable submanifold of the spacetime; it is however always continuous (and even Lipschitz continuous ). By using the flow of a vector field chosen to be complete, smooth, and timelike, it is elementary to prove that if a Cauchy surface S is C k -smooth then the spacetime is C k -diffeomorphic to the product S × R , and that any two such Cauchy surfaces are C k -diffeomorphic. [ 1 ]
Robert Geroch proved in 1970 that every globally hyperbolic spacetime has a Cauchy surface S , and that the homeomorphism (as a C 0 -diffeomorphism) to S × R can be selected so that every surface of the form S × { a } is a Cauchy surface and each curve of the form { s } × R is a continuous timelike curve. [ 2 ]
Various foundational textbooks, such as George Ellis and Stephen Hawking 's The Large Scale Structure of Space-Time and Robert Wald 's General Relativity , [ 3 ] asserted that smoothing techniques allow Geroch's result to be strengthened from a topological to a smooth context. However, this was not satisfactorily proved until work of Antonio Bernal and Miguel Sánchez in 2003. As a result of their work, it is known that every globally hyperbolic spacetime has a Cauchy surface which is smoothly embedded and spacelike. [ 4 ] As they proved in 2005, the diffeomorphism to S × R can be selected so that each surface of the form S × { a } is a spacelike smooth Cauchy surface and that each curve of the form { s } × R is a smooth timelike curve orthogonal to each surface S × { a } . [ 5 ]
Sources
This relativity -related article is a stub . You can help Wikipedia by expanding it .
This mathematical physics -related article is a stub . You can help Wikipedia by expanding it .
This differential geometry -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Geroch's_splitting_theorem |
Gerodiversity is the multicultural approach to issues of aging. This approach provides a theoretical foundation for the medical and psychological treatment of older adults within an ecological context that includes their cultural identity and heritage, social environment, community, family system, and significant relationships. [ 1 ] Gerodiversity encompasses a social justice framework, which considers the social and historical dynamics of privilege and inequality. [ 1 ] In addition to issues of aging, gerodiversity includes race, ethnicity, language, gender identity , socioeconomic status , physical ability or disability, sexual orientation , level of education, country of origin, location of residence, and religion or spirituality.
Gerodiversity builds on the field of clinical geropsychology , which applies psychological and developmental methods to understanding the behavioral, emotional, cognitive, and biological aspects of aging in the context of providing clinical care to older adults. The goal is to develop culturally competent, scientific methods for the psychological and medical treatment of the aging population. [ 1 ] According to this perspective, in order to ethically and scientifically provide optimal care to older adults, clinicians must be aware of the cultural factors in health care utilization, including use of physical and mental health care. Moreover, from this perspective, clinicians must continually work to improve their multicultural knowledge base, skill set, and attitudes towards cultural diversity.
Increased awareness and attention to gerodiversity parallels the aging demography of the United States . Older adults comprise 14.5% of the U.S. population, with those aged 65 and older numbering 46.2 million. [ 2 ] Dubbed "the Silver Tsunami", this segment of the population is rapidly growing, and the Administration on Aging expects it to double to 98 million older persons by 2060. Aging confers a unique risk of marginalization due to the intersection of advanced age and other disadvantaged factors. The domains of diversity discussed herein may intersect with age in such a way to confer a "double jeopardy". [ 3 ] More recently, attention has been paid to those who face a "triple threat of marginalization" (e.g., older lesbian women). [ 4 ] As with other conceptualizations of diversity and marginalization, advanced age and other sociodemographic variables intersect and result in unique experiences for each group and individual. Below are a few highlighted areas for consideration.
Older adults are more likely to be female. Women live longer than men, and so populations of older adults are, with each successive age bracket, increasingly dominated by women. [ 2 ] Over half (58%) of Americans over age 65 are women, a number which rises to 69% over age 85, and finally to 80% over age 100. [ 5 ]
Older men and women also have different medical and psychological health needs, as well as different profiles of risk and protective factors for acquiring physical and mental disorders. Many biological and psychosocial variables are responsible for these differences. Sex-specific hormonal and physiological differences contribute to different risks for cancer, cardiovascular disease, arthritis, osteoporosis, diabetes, depression, and dementia. Environmental and lifestyle factors, such as sleeping, eating, and exercise habits, social network, socioeconomic resources and stressors, and intellectual engagement in work and leisure activities, also significantly contribute to physical and mental health, and are differentiated between older men and older women. Older women are more likely to have a robust social network—a factor associated with better physical and mental health. Older women from other countries tend to acculturate differently than elderly men. [ 1 ] Older women are also twice as likely to live in poverty as older men. [ 6 ]
Cultural groups assign different roles and values to individuals based on their gender. Women in some cultural groups are less likely to have been employed, and have lower economic resources as a result. [ 7 ] Women are also more likely to bear most of the caregiving responsibilities for ailing family members and young children. [ 8 ]
Ethnogeriatrics is defined by the American Geriatrics Society as the "influence of ethnicity and culture on the health the well-being of older adults". [ 9 ] In 2015, non-Hispanic White Americans made up an estimated 61.72% of the US population, but that percentage is anticipated to drop to 43.65% by 2060. This demographic shift will be due in part to increases in Asian and Pacific Islander and Latino/Hispanic immigrants. [ 10 ] However, Latino and Hispanic older adults as a group are expected to increase the most dramatically, by 155%. [ 2 ]
Older adults of different ethnicities belong to different cultural groups, and may therefore have significantly different levels of access to care, different beliefs about health and aging, different expectations from care providers, and different ways of communicating their needs. [ 11 ] In addition, ethnic minorities are vulnerable to multiple forms of minority stress: racial prejudice, discrimination, and stereotyping may contribute to lower socioeconomic status, diminished access to care, and systematic disempowerment for many minority groups in the United States. These factors have a major impact on vulnerability to poorer health, risk of mental disorders, and poorer overall prognosis.
Individuals may also belong to multiple racial and ethnic groups: older adults may be biracial or multiracial, belong to indigenous or nonindigenous populations, or be immigrants or the children of immigrants. [ 12 ] Different ethnic groups have different genetic and cultural vulnerabilities to medical and psychological problems, which require culturally knowledgeable care.
Sexual and gender minorities ( lesbian , gay , bisexual , pansexual , transgender , and nongendered individuals) make up an increasing portion of aging populations, and prevalence rates of these groups are expected to rise dramatically. [ 13 ] It is estimated that 1.5 million Americans over age 65 identify as lesbian, gay, or bisexual. [ 14 ] Because LGBT older adults are less likely to have children and more likely to be single than heterosexual older adults, reduced family support and long-term care is available to them. [ 15 ] LGBT older adults also have lower rates of health insurance coverage, and fear discrimination by doctors and mental health care facilities. Among LGBT older adults, 8.3% have reported abuse by a caretaker due to sexual orientation or gender identity. Professional caregivers are also often untrained in the special needs of LGBT populations, and LGBT elders may be overlooked or ignored by many programs oriented towards older populations. [ 16 ] [ 17 ] The American Psychological Association offers a poignant article about the "double-whammy discrimination" from healthcare provider biases that affect the quality of care of older LGBT patients. [ 18 ]
Research has shown that LGBT elders tend to be unwelcome in senior centers and volunteer programs for older adults, and tend to be overlooked in public outreach programs geared towards the elderly. They also may be denied independent housing, as well as entrance to residential nursing home and retirement communities based on sexual orientation or gender identity. They may be isolated from social resources they may otherwise have had from their extended families due to discrimination. In addition, LGBT elders may still be denied visitation rights and end-of-life decision making for their partners and loved ones by hospitals, [ 19 ] despite the marriage equality ruling of 2015.
Older adults tend to be more deeply involved in religious activities than younger adults. [ 20 ] Bengston, Putney, Silverstein, and Harris studied aging patterns and generation trends regarding religiosity (namely, Christianity and Judaism ) in the United States. [ 21 ] Ultimately, the results indicated an overall aging effect with an upward drift in religious intensity and strength of beliefs. [ 21 ] Additionally, there was a generational effect indicating different conceptualizations of a monotheistic God based on one's generational cohort and a greater separation between religiosity and spirituality in later-born cohorts. [ 21 ]
In a longitudinal study, Wink and Dillon found that adults increased significantly in spirituality between late middle (mid-50s to early 60s) and older adulthood (late 60s to mid-70s); this finding was irrespective of gender and generational cohort. [ 22 ] They defined spirituality as "the self's existential search for ultimate meaning through an individualized understanding of the sacred". [ 23 ]
Glicksman suggests that one be cautious when interpreting the results of research on spirituality, suggesting that measurement scales are often biased by the Protestant traditions that have shaped the American majority culture. [ 24 ] Thus, while it is important to consider how age may impact religiosity and spirituality, it is also important to maintain a sensitive and multicultural approach to understanding an individual's unique relationship with his/her religion and how it may be impacted by other cultural variables, such as country of origin, race, and ethnicity.
Based on the research cited above, it is clear that religion and spirituality are relevant issues for older adults but that these terms may be conceptualized differently and also hold different levels of importance to different individuals. Professionals must be aware of this level of diversity when working with a geriatric population.
Older adults who are aging with disabilities are yet another diverse group of individuals, with estimates of approximately 12 to 15 million older adults aging with early-onset disabilities. [ 25 ] As medical and social advances increase and improve lifespan and quality of life for those with disabilities, this number will continue to grow. These individuals may experience unique stigma related to the aging process. A seminal and widely adopted definition of "successful aging" [ 26 ] included growing older without disability as a hallmark of such success. However, Romo and colleagues conducted a focus group of ethnically diverse older adults with disabilities and found that despite disability, the majority felt they were aging successfully. [ 27 ] Such individuals often employed diverse coping strategies to compensate for any changes in physical functioning. As with other groups of older adults, healthcare goals for those with disabilities emphasize reducing risk for chronic disease and preventing further disability and morbidity. However, such a narrow sense of "success" that precludes disability may limit inclusion and diversity. Like other aspects of gerodiversity and experience of marginalization, understanding an individual's sense of successful aging within the context of disability is subjective and likely varies between individuals. Conceptualization of gerodiversity should strive toward inclusion and thus include both disability/ability status as well as subjective experiences of "successful aging", including adaptation and coping with any physical limitations.
Socioeconomic status (SES) is frequently a combined measure of income, education, and occupation. One's SES impacts one's daily life and opportunities, especially those related to quality of life and health care. The elderly in the United States are one of the most economically vulnerable groups. As of 2006, nearly 10% of the elderly in the United States lived below the poverty line. [ 5 ] An inability to work, declines in health, and the loss of a spouse are a few of the causes contributing to a lowering of one's SES as one ages. Female and racial/ethnic minority statuses are additional risk-factors for low SES in older adults. Fleck reported that approximately 23% of older African Americans and 19% of older Hispanics live in poverty; [ 28 ] Lee and Shaw found that women are nearly twice as likely to be impoverished as males. [ 6 ]
The American Psychological Association reports that older adults with low SES can only afford substandard levels of care, if at all, and that mortality rates are significantly higher in low SES older adults. [ 29 ] This applies to both physical and mental health care. Additionally, older adults with lower education and/or who come from low-income environments are more likely to develop depression; these risk factors are also associated with higher incidences of Alzheimer's disease and dementia. [ 29 ] It is important to be aware of an older patient or client's resources and coping styles. Healthcare providers and other professionals working with older adults must also be aware of what their community may offer for aging individuals of low SES.
According to the National Rural Health Association (NRHA), the elderly make up a large percentage of the rural American population with approximately 20% of older adults living in non-metropolitan areas. [ 30 ] The living environment and occupational opportunities available to rural elders impacts their health throughout their lifetime. Furthermore, their health is impacted by limited access to care for prevention, management, and treatment of physical and mental health conditions. It can be particularly difficult for elders and their families when they have difficulty completing activities of daily living and are unable to provide their own transportation.
It is important to acknowledge and maintain awareness of the obstacles to healthcare that older individuals in rural communities face. Some older research did not find rural older adults to be disadvantaged in their use of health-related services in comparison to urban dwelling older adults. [ 31 ] [ 32 ] However, distance to providers and healthcare facilities have been cited as a common barrier among rural-dwelling veterans. [ 33 ] While not an issue exclusive to rural locations, older adults cite difficulty traveling and lack of transportation, as well as affordability of care, as the most common barriers to utilizing psychological services. [ 34 ] Transportation barriers to healthcare access may be most notable for those with lower incomes. [ 35 ] Telehealth (also known as telemedicine ; with related specialties of telepsychiatry , telemental health , and telenursing , to name a few ) is one such way that health care providers, researchers, and policy makers are striving to offset the physical distance and related barriers in rural health care delivery. Such provision of services using telecommunications can also be used to deliver care when patients are immobilized, have chronic conditions requiring monitoring, or are homebound.
An increasing number of Americans, both adults and older adults, can claim a foreign national identity. The Pew Research Center projects that by 2050, nearly one in five Americans will be foreign born. [ 36 ] Issues of national origin may dovetail with issues of citizenship for some older adults; the latter confers social and legal rights that interact with the experience of aging to include access to healthcare (including Medicare in the U.S.) and other social and financial welfare programs (e.g., Social Security ). In addition, cultural perspectives of aging can profoundly shape one's experience of growing old. Regardless of citizenship, older adults with diverse national identities may experience the aging process differently in the U.S. compared to their country of origin. There is much variability with which cultures approach aging, frailty, and death. For some, a veneration of youth marks aging as a shameful process and likely contributes to ageism in the U.S. and other Westernized countries. However, an increasingly globalized world requires a review of theoretical frameworks and research agendas to better understand cross-cultural differences in aging attitudes. [ 37 ]
A report of the APA Committee on Aging [ 38 ] offered overarching recommendations for fostering multicultural competencies in working with older adults. Clinicians, researchers, and others in organizations that interface with older adults are called upon to recognize and dispel ageism, both professionally and personally. Key to this is recognizing age as an element of cultural diversity. There are multiple levels at which to conceptualize gerodiversity, beginning with individual factors, and expanding to organizational, institutional, political, and societal frameworks. [ 1 ] The article herein emphasizes individual experiences of social inequality to consider with the acknowledgement that aging occurs in a diverse sociocultural and political milieu. Gerodiversity and multicultural competence also posits that age will intersect with other elements of diversity, with incredible variation among individuals. Above all, a gerodiversity approach emphasizes the strengths that come from cultural diversity.
Fostering such a multicultural approach to the issues of aging is a developmental process that begins with education and training and evolves over the course of one's professional and personal experiences. Molinari recommended that opportunities for education and training with older adults be available as early as high school and college. [ 39 ] There is a dearth of healthcare workers, including psychologists and physicians, adequately trained to address the needs of the aging population. Therefore, some advocate for geriatric training as a core competency in graduate and internship programs in clinical psychology. Notably, the US Health Resources and Services Administration (HRSA) has devoted funding to preparing health care providers, including nurses, social workers, and psychologists, to better meet the needs of older adults through the Geriatric Workforce Enhancement Program.
Notably, one's development and competency in gerodiversity extends past one's formal education. Molinari urges clinicians and researchers to seek independent learning opportunities with a multicultural focus and inclusion of the geriatric population. [ 39 ] Providers and policy makers are encouraged to provide outreach for physical and mental health care for older adults, perhaps in the context of equally diverse settings, such as faith communities. The APA Guidelines for Psychological Practice with Older Adults advises clinicians to promote evidence-based treatments shown to be effective with older populations, and seek supervision or consultation on such practice issues. [ 40 ] Finally, from a systems perspective, a gerodiverse approach to clinical practice, research, and policy will be fostered with research on evidence-based treatment approaches for diverse older adults, as well as dissemination of such work so that the public is educated about common mental disorders in the elderly, which may eliminate stigma. Supporting federal initiatives to train health workers in gerontology, particularly with multicultural considerations, and advocating for increased funding for research in these areas, is a crucial ongoing step. | https://en.wikipedia.org/wiki/Gerodiversity |
Gerolsteiner Brunnen GmbH & Co. KG ( Gerolsteiner ) is a leading German mineral water firm with its seat in Gerolstein in the Eifel mountains. The firm is well known for its Gerolsteiner Sprudel brand , a bottled , naturally carbonated mineral water. Gerolsteiner was also the chief sponsor of Team Gerolsteiner a cycling team.
On 1 January 1888 the mine manager, Wilhelm Castendyck, founded the firm, Gerolsteiner Sprudel, as a Gesellschaft mit beschränkter Haftung (GmbH) in Gerolstein. Its first well was drilled in the same year. By November, the water from the well had become a sort of 'official' water of the city. It was popular because of its high amount of natural carbonic acid . In 1889, its star-and-lion symbol was trademarked. By 1895, the water was being exported to Australia.
Brunnen table water supplied water to Buckingham Palace during the reign of Queen Victoria . [ 1 ]
The first exports of Gerolsteiner to the United States started in 1890, primarily to Chicago , known for its high concentration of German emigrants . Having been interrupted by World War I, U.S. shipments resumed in 1928. [ 2 ]
The Gerolsteiner factory was completely destroyed in a bombing raid during Christmas 1944. The filling machines were repaired on 1948, and by 1948 both the full building and the installation equipment had been rebuilt.
In 1986, Gerolsteiner introduced a brand with a lower amount of carbonic acid to meet changing tastes.
In 1998, the company introduced Germany's first PET reusable deposit carrying mineral water bottle to a chorus of criticism from environmental groups. [ 3 ] The use of returnable, deposit-bearing glass bottles for water, beer , and other mainstream drinks has long been normal in Germany and other European countries.
As of 2022, [update] Gerolsteiner Brunnen's majority shareholder is Bitburger Holding [ de ] . [ 4 ] | https://en.wikipedia.org/wiki/Gerolsteiner_Brunnen |
Geron Corporation is a biotechnology company located in Foster City , California which specializes in developing and commercializing therapeutic products for cancer that inhibit telomerase .
Geron, based in Foster City, California , was founded by gerontologist Mary C. West and Michael D. West , now CEO of AgeX Therapeutics . [ 2 ] [ 3 ] They secured initial venture capital investments in the company from Kleiner Perkins Caufield & Byers and Venrock . [ 4 ] The company was incorporated in 1990 and began doing business in 1992. [ 5 ] [ 6 ] John A. Scarlett was appointed CEO in 2011. [ 7 ]
The company's Scientific and Clinical Advisory Board has included Nobel laureates James Watson , Gunter Blobel , and Carol Greider , and Leonard Hayflick , known for discovering that human cells divide for a limited number of times in vitro [ 8 ] (called the Hayflick limit ). [ 9 ] [ 10 ] [ 11 ]
In 2017, Geron staff received the highest median pay in California, at $500,250. [ 12 ]
Geron Corporation has sponsored human clinical trials of several potential anti-cancer products.
In addition to testing drug candidates that exploit cancer cell's dependence on telomerase, Geron is researching the possible applications of activating the enzyme in normal cells to delay cellular senescence . The company is in the early stages of developing a telomerase based treatment for HIV called TAT0002, which is the saponin cycloastragenol in Chinese herb Astragalus propinquus . [ 25 ] Geron has granted a license to Telomerase Activation Sciences to sell TA-65 , the telomerase activator agent also derived from astragalus . [ 26 ] In October 2010 Intertek/AAC Labs, an ISO 17025 internationally recognized lab, found the largest component of TA-65 to be cycloastragenol. [ 27 ]
Geron originally investigated telomerase as a means of understanding and modifying human aging. However, Geron has ceased aging research of any kind. [ 28 ]
On January 23, 2009, Geron received FDA approval to begin Phase I testing of GRNOPC1 in humans. [ 29 ] GRNOPC1 is an embryonic stem cell based drug that is designed to treat specific forms of spinal cord injury through remyelination of damaged axons . This trial does not involve direct use of stem cells however, as GRNOPC1 is composed of oligodendrocyte progenitor cells derived from embryonic stem cell lines. Studies have shown significant restoration of mobility in animals with spinal injuries that received cells. [ 30 ]
Geron also has several other embryonic stem cell treatments that are still in the preclinical phase, including GRNCM1, a treatment for heart disease , and GRNIC1, a treatment for diabetes . In tests with diabetic mice, 80% of the mice given GRNIC1 were still alive in 50 days while the entire control group, which was given no treatment, perished. [ 31 ]
Geron sold its human stem cell research assets to Asterias in 2013. [ 32 ]
As of October 2010 and November 2010, One of Geron's most highly publicized trial therapy products has been GRNOPC1, a stem cell therapy designed to heal severe spinal cord injuries. The cells in the GRNOPC1 therapy have been coaxed into becoming early myelinated glial cells , a type of cell that insulates nerve cells . For every GRNOPC1 cell that is injected in the patient, they become six to ten cells in a few months. [ 33 ] In October 2011 updated results on four patients were released. [ 34 ] The trial was discontinued in Nov 2011.
In early 2013 BioTime, whose CEO at the time was Geron founder Michael D. West, acquired 400 patents and other intellectual property related to embryonic stem cells from Geron [ 35 ] [ 36 ] and later went on to restart the trial. [ 37 ]
Geron Corporation initially held exclusive rights to three cell types derived from embryonic stem cells , as the result of paying for the research originally conducted by Dr. James Thomson at the University of Wisconsin–Madison. [ 38 ] The patents on the other three cell types are owned by the Wisconsin Alumni Research Foundation (WARF). WARF and Geron did not charge academics to study human stem cells but did charge commercial users. In 2001 WARF came under public pressure to widen access to human stem-cell technology, and they launched legal action against Geron Corporation to recover some of the previously sold rights. The two sides agreed that Geron would keep the rights to only three cell types. [ 39 ]
In October 2006, a legal challenge was mounted to overturn these patents by The Foundation for Taxpayer and Consumer Rights and the non-profit patent-watchdog Public Patent Foundation. [ 40 ] They contended that two of the patents granted to WARF are invalid because they cover a technique published in 1992 for which a patent had already been granted to an Australian researcher. Another part of the challenge came from the molecular biologist Jeanne Loring who stated that University of Wisconsin–Madison stem cell pioneer James Thomson's techniques (currently patents held by WARF) are rendered obvious by a 1990 paper and two textbooks. [ 41 ] The outcome of this legal challenge was particularly relevant to the Geron Corporation as it can only license patents that are upheld. [ 42 ] The patents were ultimately upheld when the reexamination concluded in 2008. [ 43 ]
As an interim measure, on January 23, 2007, WARF relaxed the stem cell patents, allowing industry-sponsored research at academic and non-profit institutions without a license. [ 44 ] WARF will allow easier and simpler cost free cell transfers among researchers and would not require a license or agreement from California's taxpayer-funded stem cell research program. [ 45 ]
As a participant in the then-controversial stem cell and cloning area, Geron Corporation was asked to testify about its technology before the U.S. Congress. In 2001, when Congress was attempting to ban all forms of cloning, then Geron CEO Thomas Okarma spoke before Congress to preserve cloning for therapeutic purposes. [ 46 ] [ 47 ] [ 48 ] | https://en.wikipedia.org/wiki/Geron_Corporation |
Gerontechnology , also called gerotechnology is an inter- and multidisciplinary academic as well as a professional field that combines various disciplines of gerontology and technology . Sustainability of an aging society depends on our effectiveness in creating technological environments, including assistive technology and inclusive design , for innovative and independent living and social participation of older adults in any state of health, comfort as well as safety. In short, gerontechnology concerns matching technological environments to health , housing , mobility, communication , leisure , work and also the personality/individual dispositions of older people. Gerontechnology is most frequently identified as a subset of HealthTech and is -- since the 2010s -- more commonly referred to as AgeTech or Agetech in Europe and the United States. Research outcomes form the basis for designers , builders , engineers , manufacturers , and those in the health professions ( nursing , medicine , gerontology , geriatrics , environmental psychology , developmental psychology , etc.), to provide an optimum living environment for the widest range of ages.
Gerontechnology is considered an adjunct to the promotion of human health and physical as well as emotional well-being . It pertains to both human development and aging with the aim to compress morbidity and to increase vitality and quality of life throughout the lifespan. It creates solutions to extend the working phase in society by maximizing the vital and productive years in the later years of life, which consequently reduces the cost of care.
The overall framework of gerontechnology may be seen as a matrix of domains of human activity: (1) health & self-esteem, housing & activities of daily living , communication & governance, mobility & transport, work & leisure, as well as (2) technology interventions or impact levels (enhancement & satisfaction, prevention & engagement, compensation & assistance, care and care organisation). Underpinning all these elements are generic and applied evidence-based research findings that aid in the development of products and services.
Gerontechnology has much in common with other interdisciplinary domains, such as Assistive Technology (for the compensation & assistance and the care support & care organisation rows of the matrix), Everybodytech , Technology for All (for example Technology 4 All.org ) and Universal Design for the development of all products and services pertaining to gerontechnology.
Gerontological design focuses on providing effective solutions to improve the way of life for aging people, through gerontological knowledge and design research methods to obtain a better understanding of individuals' preferences and requirements.
Gerontological design also refers specifically to the study and practice of building design methods that support older users in the built environment. Some universities host professors, commonly in architecture or interior design departments, that specialize in the study and teaching of this design specialization. Not only does this include the examination of building design characteristics that impact older adults' physiological well-being, but it can also include the investigation of building design characteristics that impact informational needs (i.e. finding one's way around in a space) or social interaction needs (Campbell, 2012).
Between 2008 and 2030, Singapore will witness an age profile shift in its population's history. In 2005, one in 12 residents was 65 years or older. By 2030, one in five residents will be 65 years or older. [ 1 ] Studies show that in 2002, 7% of the world's population is aged 65 and above. By 2050, it is envisaged that the percentage could rise to nearly 17%. [ 2 ] The ageing population and its impact on economics , politics , education and lifestyle is no longer an isolated issue but a global concern. Products and services relevant to the "silver industry" or the "mature market" increasingly abound in the marketplace. The demand for designers with a keen sense for the aging population's needs who employ gerontological design process knowledge concomitantly rises.
An international academic journal with delayed open-access, Gerontechnology [1] , is published by the International Society for Gerontechnology (ISG) [2] .
A comprehensive volume titled Gerontechnology [3] edited by Sunkyo Kwon has been published in 2016/2017.
Age technology (AgeTech/Agetech) has been used to enhance aspects of insurance, domiciliary care, residential and nursing homes, health care, and risk management. The services may originate from various independent service providers or the interconnection of devices and services enabled through open APIs. Commercial businesses with an ageing component including the opportunities around the “Silver Economy” – providing services for the ‘wants’ of the older demographic, supporting independent living – addressing the ‘needs’ of the older demographic, longevity – extending healthy lifespan and geroscience.
In the US, startup Aging2.0 launched in 2015 and has since organized 170 meet-up events, opened volunteer chapters in 30 countries and signed up 30 companies for its own accelerator program. Amongst these, SingFit “makes it easy for everyone to become a music therapist”, WalkJoy is a wearable sensor that measures a person’s gait and alerts caregivers when someone could be about to fall. Active Protective is a personal airbag that inflates to stop someone breaking their hip. And Vynca records a person’s dying wishes, so families aren’t unsure when the time comes. The company Honor, which connects seniors, caregivers and their families, recently raised $20 million, the biggest funding in the emerging category so far. In Europe, London-based AgeTech startup Birdie secured a €7 million Series A to help elderly adults live independently while independent living system Kraydel has raised over £1m in innovation and public sector grants to develop its smart device which sits on top of the TV, linking elderly people to their carers or family members, through their TV screens.
The first ISG Masterclass [4] for PhD students in 2006 produced a scheme to support gerontechnological research. | https://en.wikipedia.org/wiki/Gerontechnology |
Gerontogens are environmental agents that can accelerate aging in some animals, including humans. Gerontogens are typically toxic chemical agents, such as those found in cigarette smoke. However, many other things can act as gerontogens, including ultraviolet radiation , chemotherapy treatment, and arsenic . [ 1 ]
Gerontogens work in two different ways. They can shorten telomeres , repetitive nucleotide sequences at the end of chromosomes , which accelerates cell destruction. Gerontogens can also accelerate the rate of cellular senescence , where normal diploid cells cease to divide. This can be measured using the body's levels of the protein p16 . [ 2 ] [ 3 ]
This toxicology -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Gerontogens |
1800s: Martineau · Tocqueville · Marx · Spencer · Le Bon · Ward · Pareto · Tönnies · Veblen · Simmel · Durkheim · Addams · Mead · Weber · Du Bois · Mannheim · Elias
Gerontology ( / ˌ dʒ ɛr ən ˈ t ɒ l ə dʒ i / JERR -ən- TOL -ə-jee ) is the study of the social , cultural , psychological , cognitive , and biological aspects of aging . The word was coined by Ilya Ilyich Mechnikov in 1903, from the Greek γέρων ( gérōn ), meaning "old man", and -λογία ( -logía ), meaning "study of". [ 1 ] [ 2 ] [ 3 ] [ 4 ] The field is distinguished from geriatrics , which is the branch of medicine that specializes in the treatment of existing disease in older adults. Gerontologists include researchers and practitioners in the fields of biology, nursing, medicine , criminology , dentistry, social work , physical and occupational therapy , psychology, psychiatry, sociology , economics, political science , architecture, geography, pharmacy, public health , housing, and anthropology. [ 5 ]
The multidisciplinary nature of gerontology means that there are a number of sub-fields which overlap with gerontology. There are policy issues, for example, involved in government planning and the operation of nursing homes, investigating the effects of an aging population on society, and the design of residential spaces for older people that facilitate the development of a sense of place or home. Dr. Lawton, a behavioral psychologist at the Philadelphia Geriatric Center, was among the first to recognize the need for living spaces designed to accommodate the elderly, especially those with Alzheimer's disease. As an academic discipline the field is relatively new. The USC Leonard Davis School of Gerontology created the first PhD, master's and bachelor's degree programs in gerontology in 1975.
In the Islamic Golden Age , several physicians wrote on issues related to Gerontology. Avicenna 's The Canon of Medicine (1025) offered instruction for the care of the aged, including diet and remedies for problems including constipation . [ 6 ] Arabic physician Ibn Al-Jazzar Al-Qayrawani (Algizar, c. 898–980) wrote on the aches and conditions of the elderly. [ 7 ] His scholarly work covers sleep disorders , forgetfulness , how to strengthen memory , [ 8 ] [ 9 ] and causes of mortality . [ 10 ] Ishaq ibn Hunayn (died 910) also wrote works on the treatments for forgetfulness. [ 11 ]
While the number of aged humans, and the life expectancy , tended to increase in every century since the 14th, society tended to consider caring for an elderly relative as a family issue. It was not until the coming of the Industrial Revolution that ideas shifted in favor of a societal care-system. Some early pioneers, such as Michel Eugène Chevreul , who himself lived to be 102, believed that aging itself should be a science to be studied. Élie Metchnikoff coined the term "gerontology" in 1903. [ 12 ]
Modern pioneers like James Birren began organizing gerontology as its own field in the 1940s, later being involved in starting a US government agency on aging—the National Institute on Aging [ 13 ] —programs in gerontology at the University of Southern California and University of California, Los Angeles , and as past president of the Gerontological Society of America (founded in 1945). [ 14 ]
With the population of people over 60 years old expected to be some 22% of the world's population by 2050, assessment and treatment methods for age-related disease burden—the term geroscience emerged in the early 21st century. [ 15 ] [ 16 ] [ 17 ]
The world is forecast to undergo rapid population aging in the next several decades. In 1900, there were 3.1 million people aged 65 years and older living in the United States . However, this population continued to grow throughout the 20th century and reached 31.2, 35, and 40.3 million people in 1990, 2000, and 2010, respectively. Notably, in the United States and across the world, the "baby boomer" generation began to turn 65 in 2011. Recently, the population aged 65 years and older has grown at a faster rate than the total population in the United States. The total population increased by 9.7%, from 281.4 million to 308.7 million, between 2000 and 2010. However, the population aged 65 years and older increased by 15.1% during the same period. [ 18 ] It has been estimated that 25% of the population in the United States and Canada will be aged 65 years and older by 2025. Moreover, by 2050, it is predicted that, for the first time in United States history, the number of individuals aged 60 years and older will be greater than the number of children aged 0 to 14 years. [ 19 ] Those aged 85 years and older (oldest-old) are projected to increase from 5.3 million to 21 million by 2050. [ 20 ] Adults aged 85–89 years constituted the greatest segment of the oldest-old in 1990, 2000, and 2010. However, the largest percentage point increase among the oldest-old occurred in the 90- to 94-year-old age group, which increased from 25.0% in 1990 to 26.4% in 2010. [ 18 ]
With the rapid growth of the aging population, social work education and training specialized in older adults and practitioners interested in working with older adults are increasingly in demand. [ 21 ] [ 22 ]
There has been a considerable disparity between the number of men and women in the older population in the United States. In both 2000 and 2010, women outnumbered men in the older population at every single year of age (e.g., 65 to 100 years and over). The sex ratio , which is a measure used to indicate the balance of males to females in a population, is calculated by taking the number of males divided by the number of females, and multiplying by 100. Therefore, the sex ratio is the number of males per 100 females. In 2010, there were 90.5 males per 100 females in the 65-year-old population. However, this represented an increase from 1990 when there were 82.7 males per 100 females, and from 2000 when the sex ratio was 88.1. Although the gender gap between men and women has narrowed, women continue to have a greater life expectancy and lower mortality rates at older ages relative to men. For example, the Census 2010 reported that there were approximately twice as many women as men living in the United States at 89 years of age (361,309 versus 176,689, respectively). [ 18 ]
The number and percentage of older adults living in the United States vary across the four different regions (Northeast, Midwest, West, and South) defined by the United States census. In 2010, the South contained the greatest number of people aged 65 years and older and 85 years and older. However, proportionately, the Northeast contains the largest percentage of adults aged 65 years and older (14.1%), followed by the Midwest (13.5%), the South (13.0%), and the West (11.9%). Relative to the Census 2000 , all geographic regions demonstrated positive growth in the population of adults aged 65 years and older and 85 years and older. The most rapid growth in the population of adults aged 65 years and older was evident in the West (23.5%), which showed an increase from 6.9 million in 2000 to 8.5 million in 2010. Likewise, in the population aged 85 years and older, the West (42.8%) also showed the fastest growth and increased from 806,000 in 2000 to 1.2 million in 2010. It is worth highlighting that Rhode Island was the only state that experienced a reduction in the number of people aged 65 years and older, and declined from 152,402 in 2000 to 151,881 in 2010. Conversely, all states exhibited an increase in the population of adults aged 85 years and older from 2000 to 2010. [ 18 ]
As with many disciplines , over the course of the 20th and 21st centuries the field of gerontology has sub-divided into multiple specific disciplines focused on increasingly narrow aspects of the aging process . [ 23 ]
Biogerontology is the special sub-field of gerontology concerned with the biological aging process, its evolutionary origins, and potential means to intervene in the process. Aim of biogerontology is to prevent age-related disease by intervening in aging processes or even eliminate aging per se. Some argue that aging fits the criteria of disease, therefore aging is disease and should be treated as disease. [ 24 ] [ 25 ] [ 26 ] In 2008 Aubrey de Grey said that in case of suitable funding and involvement of specialists there is a 50% chance, that in 25–30 years humans will have technology saving people from dying of old age, regardless of the age at which they will be at that time. [ 27 ] His idea is to repair inside cells and between them all that can be repaired using modern technology, allowing people to live until time when technology progress will allow to cure deeper damage. This concept got the name " longevity escape velocity ".
A meta analysis of 36 studies concluded that there is an association between age and DNA damage in humans, [ 28 ] a finding consistent with the DNA damage theory of aging .
Social gerontology is a multi-disciplinary sub-field that specializes in studying or working with older adults. Social gerontologists may have degrees or training in social work , nursing , psychology , sociology , demography , public health , or other social science disciplines. Social gerontologists are responsible for educating, researching, and advancing the broader causes of older people. [ 29 ]
Because issues of life span and life extension need numbers to quantify them, there is an overlap with demography . Those who study the demography of the human life span differ from those who study the social demographics of aging.
Several theories of aging are developed to observe the aging process of older adults in society as well as how these processes are interpreted by men and women as they age. [ 30 ]
Activity theory was developed and elaborated by Cavan, Havighurst, and Albrecht. According to this theory, older adults' self-concept depends on social interactions. In order for older adults to maintain morale in old age, substitutions must be made for lost roles. Examples of lost roles include retirement from a job or loss of a spouse. [ 30 ]
Activity is preferable to inactivity because it facilitates well-being on multiple levels. Because of improved general health and prosperity in the older population, remaining active is more feasible now than when this theory was first proposed by Havighurst nearly six decades ago. The activity theory is applicable for a stable, post-industrial society , which offers its older members many opportunities for meaningful participation. Weakness: Some aging persons cannot maintain a middle-aged lifestyle, due to functional limitations, lack of income, or lack of a desire to do so. Many older adults lack the resources to maintain active roles in society. On the flip side, some elders may insist on continuing activities in late life that pose a danger to themselves and others, such as driving at night with low visual acuity or doing maintenance work to the house while climbing with severely arthritic knees. In doing so, they are denying their limitations and engaging in unsafe behaviors. [ 31 ]
Disengagement theory was developed by Cumming and Henry. According to this theory, older adults and society engage in a mutual separation from each other. An example of mutual separation is retirement from the workforce. A key assumption of this theory is that older adults lose "ego-energy" and become increasingly self-absorbed. Additionally, disengagement leads to higher morale maintenance than if older adults try to maintain social involvement. This theory is heavily criticized for having an escape clause—namely, that older adults who remain engaged in society are unsuccessful adjusters to old age. [ 30 ]
Gradual withdrawal from society and relationships preserves social equilibrium and promotes self-reflection for elders who are freed from societal roles. It furnishes an orderly means for the transfer of knowledge, capital, and power from the older generation to the young. It makes it possible for society to continue functioning after valuable older members die.
According to this theory, older adults born during different time periods form cohorts that define "age strata". There are two differences among strata: chronological age and historical experience. This theory makes two arguments. 1. Age is a mechanism for regulating behavior and as a result determines access to positions of power. 2. Birth cohorts play an influential role in the process of social change. [ 30 ]
According to this theory, which stems from the life course perspective aging occurs from birth to death. Aging involves social, psychological, and biological processes. [ 32 ] Additionally, aging experiences are shaped by cohort and period effects. [ 30 ]
Also reflecting the life course focus, consider the implications for how societies might function when age-based norms vanish—a consequence of the deinstitutionalization of the life course—and suggest that these implications pose new challenges for theorizing aging and the life course in postindustrial societies. Dramatic reductions in mortality, morbidity, and fertility over the past several decades have so shaken up the organization of the life course and the nature of educational, work, family, and leisure experiences that it is now possible for individuals to become old in new ways. The configurations and content of other life stages are being altered as well, especially for women. In consequence, theories of age and aging will need to be reconceptualized. [ 33 ]
According to this theory, which was developed beginning in the 1960s by Derek Price and Robert Merton and elaborated on by several researchers such as Dale Dannefer, [ 34 ] inequalities have a tendency to become more pronounced throughout the aging process. A paradigm of this theory can be expressed in the adage " the rich get richer and the poor get poorer ". Advantages and disadvantages in early life stages have a profound effect throughout the life span. However, advantages and disadvantages in middle adulthood have a direct influence on economic and health status in later life. [ 30 ]
Environmental gerontology is a specialization within gerontology that seeks an understanding and interventions to optimize the relationship between aging persons and their physical and social environments. [ 35 ] [ 36 ] [ 37 ]
The field emerged in the 1930s during the first studies on behavioral and social gerontology. In the 1970s and 1980s, research confirmed the importance of the physical and social environment in understanding the aging population and improved the quality of life in old age. [ 38 ] Studies of environmental gerontology indicate that older people prefer to age in their immediate environment, whereas spatial experience and place attachment are important for understanding the process. [ 39 ]
Some research indicates that the physical-social environment is related to the longevity and quality of life of the elderly . Precisely, the natural environment (such as natural therapeutic landscapes , therapeutic garden ) contributes to active and healthy aging in the place. [ 40 ] [ 41 ]
Jurisprudential gerontology (sometimes referred to as "geriatric jurisprudence") is a specialization within gerontology that looks into the ways laws and legal structures interact with the aging experience. The field started from legal scholars in the field of elder law , which found that looking into legal issues of older persons without a broader inter-disciplinary perspective does not provide the ideal legal outcome. Using theories such as therapeutic jurisprudence , jurisprudential scholars critically examined existing legal institutions (e.g. adult guardianship, end of life care, or nursing homes regulations) and showed how law should look more closely to the social and psychological aspects of its real-life operation. [ 42 ] Other streams within jurisprudential gerontology also encouraged physicians and lawyers to try to improve their cooperation and better understand how laws and regulatory institutions affect health and well-being of older persons. [ 43 ] | https://en.wikipedia.org/wiki/Gerontology |
A gerontoplast is a plastid that develops from a chloroplast during the senescing of plant foliage . [ 1 ] Gerontoplast development is generally seen to be the process of grana being unstacked, loss of thylakoid membranes , and large accumulation of plastoglobuli .
The term gerontoplast was first introduced in 1977 to define the unique features of the plastid formed during leaf senescence. [ 2 ] The process of senescence brings about regulated dismantling of cellular organelles involved in photosynthesis . Chloroplasts responsible for gas exchange in stomata are the last organelles to degrade during senescence, and give plants the green color. [ 1 ] The formation of gerontoplasts from chloroplasts during senescence involves extensive structural modifications of the thylakoid membrane with the concomitant formation of a large number of plastoglobuli with lipophilic materials. The envelope of the plastid, however, remains intact. [ 2 ]
This cell biology article is a stub . You can help Wikipedia by expanding it .
This photosynthesis article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Gerontoplast |
A geroprotector aims to affect the root cause of aging and age-related diseases, and thus prolong the life span of animals. [ 1 ] [ 2 ] Some possible geroprotectors include melatonin , [ 3 ] carnosine , [ 4 ] metformin , [ 5 ] rapamycin , [ 6 ] nicotinamide mononucleotide (NMN), [ 7 ] delta sleep-inducing peptide [ 8 ] and glycine . [ 9 ]
Geroprotectors could belong to multiple classes, depending on which of the hallmarks of aging they influence. [ 10 ] [ 11 ]
The distinction between geroprotectors and senotherapeutics is an evolving area of aging research. Geroprotectors broadly aim to target multiple mechanisms of aging, prolonging lifespan and healthspan by addressing the fundamental causes of aging. Senotherapeutics, on the other hand, are a subset of therapies that specifically target senescent cells , which are dysfunctional cells that accumulate with age and contribute to inflammation and age-related diseases. [ 12 ]
This article about medicinal chemistry is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Geroprotector |
Gerovital H3 (or procaine hydrochloride and products known as GH3 and other variants, which may or may not be identical to Gerovital H3) is a preparation developed during the 1950s and promoted by its advocates as an effective anti-aging treatment. In the United States, the FDA bans Gerovital H3 from interstate commerce as an unapproved drug and, since 1982, has prohibited its importation.
Gerovital is promoted with unsupported claims of its curative abilities for a wide range of human ailments; research has found no evidence that it has any health benefit or "anti-aging" properties. [ 1 ]
The impetus for developing the drug is sometimes alleged to have come from Nicolae Ceaușescu , who is also wrongly claimed to have funded the establishment of a research organization - the National Institute of Geriatrics, in Bucharest , Romania, headed by Ana Aslan (1897–1988). [ 1 ]
From the 1950s until her death in 1988, Aslan promoted Gerovital H3 with great success. In the 1960s and 1970s her Romanian clinic, the Parhon Institute, became a mecca for celebrities seeking treatment, and an upscale tourist attraction. The New York Times referred to Gerovital's "jet-set aura", noting that Aslan had been covered in "society columns where such public figures as Nikita S. Khrushchev , Konrad Adenauer , and Ibn Saud have been listed among the multitudes said to have taken the drug." As late as 1988, an advertisement by the Romanian National Tourist Office lauded "the picturesque and exciting cities, scenic delights, famous resorts (including Gerovital H3 treatment centers), cultural and historic treasures that await the traveler to Romania." [ 2 ]
With the rise of the Web Gerovital has enjoyed a new lease of promotional life as it is promoted by many sites with claims of its "cure-all" abilities. [ 1 ]
A 1973 New York Times [ medical citation needed ] article said "cold water was thrown on [Gerovital]'s reputation years ago" by "three reports published simultaneously in British Medical Journal [that said it] found no merit for procaine hydrochloride for any of the problems of aging." [ 3 ]
Some clinical trials in the mid-to-late 1970s suggested that Gerovital H3 acts as a weak, competitive, reversible MAO inhibitor , and so may have some antidepressant value, but otherwise has a negligible effect on disease. In 1994, the U.S. FDA Consumer magazine said: "No health claims for Gerovital have been substantiated, and FDA considers it an unapproved new drug. It has caused low blood pressure, respiratory difficulties, and convulsions in some users." [ 4 ] Suppliers assert that the product is safe, and one cites a brief quotation from a newspaper article that says "while as early as 1973 Elmer Gardner of the FDA's Bureau of Drugs stated 'There is no safety problem with Gerovital H-3. ' " [ 5 ]
There is no evidence that Gerovital is helpful in slowing aging or treating illness. [ 1 ]
Procaine itself is often considered to be a drug. Earlier references by advocates of Gerovital H3 refer to it as a drug. Hoffer and Walker (1980) call it a "youth drug". Mircea Dumitru, Aslan's colleague and personal physician, describes it as "a complex drug acting like the procaine molecule. The addition of benzoic acid, potassium and disodium phosphate increase the effects of Gerovital-H3 biotrophic treatment." [ 6 ]
As of 2004 [update] , the FDA's 1982 automatic detention alert is still in effect and bans the import of Gerovital H3 into the U.S. as "a new drug within the meaning of 201(p), without an approved new drug application [Unapproved New Drug, Section 505(a)]." [ 7 ]
The ban covers: | https://en.wikipedia.org/wiki/Gerovital |
Gerrit Mannoury (17 May 1867 – 30 January 1956) was a Dutch philosopher and mathematician , professor at the University of Amsterdam and communist , known as the central figure in the signific circle , a Dutch counterpart of the Vienna circle . [ 1 ]
Gerrit Mannoury was born on 17 May 1867 in Wormerveer , and died on 30 January 1956 in Amsterdam . On 8 August 1907 he married Elizabeth Maria Berkelbach van der Sprenkel, [ 2 ] with whom he had three daughters and a son, Jan Mannoury. His father Gerrit Mannoury, a sea-captain, had died in China when he was three years old. [ 3 ] He attended the Hogere Burgerschool (HBS) in Amsterdam, where he graduated in 1885. The same year he received a Teacher's Degree in Accounting and in Mechanics. In 1902 he also received a Teacher's Degree in Mathematics. Mannoury was a self-educated mathematician. Because he was a teacher he couldn't attend lessons at the University of Amsterdam. He did receive private lessons from Diederik Korteweg . He was awarded a PhD in Mathematics late in life, in 1946, with L.E.J. Brouwer as his promotores. [ 4 ]
Mannoury was a committed socialist throughout his life. In 1901 he helped to found the scientific bureau of the Social Democratic Workers' Party (SDAP), of which he was secretary until 1906. In 1909 Mannoury left the SDAP with Orthodox Marxist opposition, and took a seat on the party board of the newly founded Social Democratic Party (SDP). After the Russian October Revolution , the SDP renamed itself in 1918 to the Communist Party of Holland (CPH) (later the Communist Party of the Netherlands).
Mannoury started working in primary education in Amsterdam , Bloemendaal and Helmond . In 1910 he started teaching at the Hoogere Burger School (HBS) at Vlissingen . In 1902 he had been appointed privaatdocent at the University of Amsterdam and in 1917 he was made professor there. In 1932 Mannoury was disbarred from the Communist Party for supporting the exiled Leon Trotsky . Following this event, Mannoury's political activity was mostly centered for the abolition of the death penalty.
He retired in 1937. He lectured on the philosophy of mathematics, and on mechanics, analytics and descriptive and projective geometry . [ 5 ]
Mannoury was, with Diederik Korteweg , one of the most important teachers of Luitzen Egbertus Jan Brouwer at Amsterdam University, Mannoury especially philosophically. The first appearance of the names " formalism " and " intuitionism " in Brouwer's writings, were in a review of Gerrit Mannoury's book Methodologisches und Philosophisches zur Elementar-Mathematik (Methodological and philosophical remarks on elementary mathematics) from 1909. [ 6 ] Two other Dutch scientists he inspired were philosopher and logician Evert W. Beth and psychologist Adriaan de Groot .
He died in Amsterdam.
Mannoury's main inspirations were G. W. F. Hegel , G.J.P.J. Bolland and F. H. Bradley . He was also inspired by the work of Friedrich Nietzsche , Baruch Spinoza , the French mathematician philosopher of science Henri Poincaré and the English positivism of Bertrand Russell . Mannoury combined a logical-mathematical way of thinking with a deep insight into the human soul. [ 3 ]
Mannoury was a prolific and polymathic writer who published books, articles, reviews, and pamphlets. [ 7 ] | https://en.wikipedia.org/wiki/Gerrit_Mannoury |
In mathematics , the Gershgorin circle theorem may be used to bound the spectrum of a square matrix . It was first published by the Soviet mathematician Semyon Aronovich Gershgorin in 1931. Gershgorin's name has been transliterated in several different ways, including Geršgorin, Gerschgorin, Gershgorin, Hershhorn, and Hirschhorn.
Let A {\displaystyle A} be a complex n × n {\displaystyle n\times n} matrix, with entries a i j {\displaystyle a_{ij}} . For i ∈ { 1 , … , n } {\displaystyle i\in \{1,\dots ,n\}} let R i {\displaystyle R_{i}} be the sum of the absolute values of the non-diagonal entries in the i {\displaystyle i} -th row:
Let D ( a i i , R i ) ⊆ C {\displaystyle D(a_{ii},R_{i})\subseteq \mathbb {C} } be a closed disc centered at a i i {\displaystyle a_{ii}} with radius R i {\displaystyle R_{i}} . Such a disc is called a Gershgorin disc.
Proof. Let λ {\displaystyle \lambda } be an eigenvalue of A {\displaystyle A} with corresponding eigenvector x = ( x j ) {\displaystyle x=(x_{j})} . Find i such that the element of x with the largest absolute value is x i {\displaystyle x_{i}} . Since A x = λ x {\displaystyle Ax=\lambda x} , in particular we take the i th component of that equation to get:
Taking a i i {\displaystyle a_{ii}} to the other side:
Therefore, applying the triangle inequality and recalling that | x j | | x i | ≤ 1 {\displaystyle {\frac {\left|x_{j}\right|}{\left|x_{i}\right|}}\leq 1} based on how we picked i ,
Proof. Apply the Theorem to A T while recognizing that the eigenvalues of the transpose are the same as those of the original matrix.
Example. For a diagonal matrix , the Gershgorin discs coincide with the spectrum. Conversely, if the Gershgorin discs coincide with the spectrum, the matrix is diagonal.
One way to interpret this theorem is that if the off-diagonal entries of a square matrix over the complex numbers have small norms , the eigenvalues of the matrix cannot be "far from" the diagonal entries of the matrix. Therefore, by reducing the norms of off-diagonal entries one can attempt to approximate the eigenvalues of the matrix. Of course, diagonal entries may change in the process of minimizing off-diagonal entries.
The theorem does not claim that there is one disc for each eigenvalue; if anything, the discs rather correspond to the axes in C n {\displaystyle \mathbb {C} ^{n}} , and each expresses a bound on precisely those eigenvalues whose eigenspaces are closest to one particular axis. In the matrix
— which by construction has eigenvalues a {\displaystyle a} , b {\displaystyle b} , and c {\displaystyle c} with eigenvectors ( 3 1 1 ) {\displaystyle \left({\begin{smallmatrix}3\\1\\1\end{smallmatrix}}\right)} , ( 2 1 0 ) {\displaystyle \left({\begin{smallmatrix}2\\1\\0\end{smallmatrix}}\right)} , and ( 2 0 1 ) {\displaystyle \left({\begin{smallmatrix}2\\0\\1\end{smallmatrix}}\right)} — it is easy to see that the disc for row 2 covers a {\displaystyle a} and b {\displaystyle b} while the disc for row 3 covers a {\displaystyle a} and c {\displaystyle c} . This is however just a happy coincidence; if working through the steps of the proof one finds that it in each eigenvector is the first element that is the largest (every eigenspace is closer to the first axis than to any other axis), so the theorem only promises that the disc for row 1 (whose radius can be twice the sum of the other two radii) covers all three eigenvalues.
If one of the discs is disjoint from the others then it contains exactly one eigenvalue. If however it meets another disc it is possible that it contains no eigenvalue (for example, A = ( 0 1 4 0 ) {\displaystyle A=\left({\begin{smallmatrix}0&1\\4&0\end{smallmatrix}}\right)} or A = ( 1 − 2 1 − 1 ) {\displaystyle A=\left({\begin{smallmatrix}1&-2\\1&-1\end{smallmatrix}}\right)} ). In the general case the theorem can be strengthened as follows:
Theorem : If the union of k discs is disjoint from the union of the other n − k discs then the former union contains exactly k and the latter n − k eigenvalues of A , when the eigenvalues are counted with their algebraic multiplicities.
Proof : Let D be the diagonal matrix with entries equal to the diagonal entries of A and let
We will use the fact that the eigenvalues are continuous in t {\displaystyle t} , and show that if any eigenvalue moves from one of the unions to the other, then it must be outside all the discs for some t {\displaystyle t} , which is a contradiction.
The statement is true for D = B ( 0 ) {\displaystyle D=B(0)} . The diagonal entries of B ( t ) {\displaystyle B(t)} are equal to that of A , thus the centers of the Gershgorin circles are the same, however their radii are t times that of A. Therefore, the union of the corresponding k discs of B ( t ) {\displaystyle B(t)} is disjoint from the union of the remaining n-k for all t ∈ [ 0 , 1 ] {\displaystyle t\in [0,1]} . The discs are closed, so the distance of the two unions for A is d > 0 {\displaystyle d>0} . The distance for B ( t ) {\displaystyle B(t)} is a decreasing function of t , so it is always at least d . Since the eigenvalues of B ( t ) {\displaystyle B(t)} are a continuous function of t , for any eigenvalue λ ( t ) {\displaystyle \lambda (t)} of B ( t ) {\displaystyle B(t)} in the union of the k discs its distance d ( t ) {\displaystyle d(t)} from the union of the other n-k discs is also continuous. Obviously d ( 0 ) ≥ d {\displaystyle d(0)\geq d} , and assume λ ( 1 ) {\displaystyle \lambda (1)} lies in the union of the n-k discs. Then d ( 1 ) = 0 {\displaystyle d(1)=0} , so there exists 0 < t 0 < 1 {\displaystyle 0<t_{0}<1} such that 0 < d ( t 0 ) < d {\displaystyle 0<d(t_{0})<d} . But this means λ ( t 0 ) {\displaystyle \lambda (t_{0})} lies outside the Gershgorin discs, which is impossible. Therefore λ ( 1 ) {\displaystyle \lambda (1)} lies in the union of the k discs, and the theorem is proven.
Remarks: It is necessary to count the eigenvalues with respect to their algebraic multiplicities. Here is a counter-example :
Consider the matrix, [ 5 1 0 0 0 0 5 1 0 0 0 0 5 0 0 0 0 0 1 1 0 0 0 0 1 ] {\displaystyle {\begin{bmatrix}5&1&0&0&0\\0&5&1&0&0\\0&0&5&0&0\\0&0&0&1&1\\0&0&0&0&1\end{bmatrix}}}
The union of the first 3 disks does not intersect the last 2, but the matrix has only 2 eigenvectors, e1,e4, and therefore only 2 eigenvalues, demonstrating that theorem is false in its formulation. The demonstration of the shows only that eigenvalues are distinct, however any affirmation about number of them is something that does not fit, and this is a counterexample.
Added Remark:
The Gershgorin circle theorem is useful in solving matrix equations of the form Ax = b for x where b is a vector and A is a matrix with a large condition number .
In this kind of problem, the error in the final result is usually of the same order of magnitude as the error in the initial data multiplied by the condition number of A . For instance, if b is known to six decimal places and the condition number of A is 1000 then we can only be confident that x is accurate to three decimal places. For very high condition numbers, even very small errors due to rounding can be magnified to such an extent that the result is meaningless.
It would be good to reduce the condition number of A . This can be done by preconditioning : A matrix P such that P ≈ A −1 is constructed, and then the equation PAx = Pb is solved for x . Using the exact inverse of A would be nice but finding the inverse of a matrix is something we want to avoid because of the computational expense.
Now, since PA ≈ I where I is the identity matrix, the eigenvalues of PA should all be close to 1. By the Gershgorin circle theorem, every eigenvalue of PA lies within a known area and so we can form a rough estimate of how good our choice of P was.
Use the Gershgorin circle theorem to estimate the eigenvalues of:
Starting with row one, we take the element on the diagonal, a ii as the center for the disc. We then take the remaining elements in the row and apply the formula
to obtain the following four discs:
Note that we can improve the accuracy of the last two discs by applying the formula to the corresponding columns of the matrix, obtaining D ( 2 , 1.2 ) {\displaystyle D(2,1.2)} and D ( − 11 , 2.2 ) {\displaystyle D(-11,2.2)} .
The eigenvalues are -10.870, 1.906, 10.046, 7.918. Note that this is a (column) diagonally dominant matrix : | a i i | > ∑ j ≠ i | a j i | {\textstyle |a_{ii}|>\sum _{j\neq i}|a_{ji}|} . This means that most of the matrix is in the diagonal, which explains why the eigenvalues are so close to the centers of the circles, and the estimates are very good. For a random matrix, we would expect the eigenvalues to be substantially further from the centers of the circles.
While the original Gershgorin Circle Theorem applies to all complex square matrices, stronger conclusions can be drawn when the matrix has additional structure, such as being symmetric or irreducible.
For a real symmetric matrix A ∈ R n × n {\displaystyle A\in \mathbb {R} ^{n\times n}} , the Gershgorin disks reduce to intervals on the real line. In this case:
Additionally, a refinement due to Olga Taussky provides further structure for irreducible matrices:
This result — known as Taussky’s Theorem — highlights how the geometry of the Gershgorin intervals tightly constrains eigenvalue locations when the matrix exhibits sufficient connectivity and structure.
[ 3 ]
Consider the symmetric and irreducible tridiagonal matrix:
This matrix is real, symmetric, and irreducible. Each Gershgorin disk reduces to an interval on the real line:
The union of these intervals covers [0, 4].
The eigenvalues of this matrix are:
Observe that the smallest eigenvalue, λ 1 = 0 {\displaystyle \lambda _{1}=0} , lies exactly at the left endpoint of all three Gershgorin intervals: [0, 2], [0, 4], and [0, 2].
By Taussky’s Theorem , since the matrix is symmetric and irreducible, and one eigenvalue lies at the boundary of a Gershgorin interval, that eigenvalue must lie at the boundary of every Gershgorin interval. This condition is satisfied here.
This example illustrates how eigenvalues of symmetric, irreducible matrices can lie exactly on the boundaries of all Gershgorin intervals, as constrained by Taussky’s refinement of the Gershgorin Circle Theorem. | https://en.wikipedia.org/wiki/Gershgorin_circle_theorem |
In mathematics and theoretical physics , a Gerstenhaber algebra (sometimes called an antibracket algebra or braid algebra ) is an algebraic structure discovered by Murray Gerstenhaber (1963) that combines the structures of a supercommutative ring and a graded Lie superalgebra . It is used in the Batalin–Vilkovisky formalism . It appears also in the generalization of Hamiltonian
formalism known as the De Donder–Weyl theory as the algebra of generalized Poisson brackets defined on differential forms.
A Gerstenhaber algebra is a graded-commutative algebra with a Lie bracket of degree −1 satisfying the Poisson identity . Everything is understood to satisfy the usual superalgebra sign conventions. More precisely, the algebra has two products, one written as ordinary multiplication and one written as [,], and a Z -grading called degree (in theoretical physics sometimes called ghost number ). The degree of an element a is denoted by | a |. These satisfy the identities
Gerstenhaber algebras differ from Poisson superalgebras in that the Lie bracket has degree −1 rather than degree 0. The Jacobi identity may also be expressed in a symmetrical form
This article about theoretical physics is a stub . You can help Wikipedia by expanding it .
This algebra -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Gerstenhaber_algebra |
The Gesellschaft zur Erhaltung alter und gefährdeter Haustierrassen [ a ] or GEH is a German national association for the conservation of historic and endangered domestic animal breeds .
The GEH was founded on 5 December 1981 in the Rottal , in Lower Bavaria in southern Germany. [ 2 ] It has about 2100 members. Since it was founded, no domestic livestock breed has become extinct in Germany. [ 3 ]
The GEH co-operates with other national and international organisations for the conservation of biodiversity . [ 3 ] It publishes an annual Rote Liste or red list of endangered breeds of livestock, which attributes one of four categories of conservation risk to domestic breeds of cattle, dogs, goats, horses, pigs, rabbits and sheep, of chickens, ducks, geese and turkeys, and of bees; listing of domestic pigeon breeds is in preparation. [ 4 ] Some breeds from outside Germany are listed separately. The four levels of risk are:
The risk level is calculated using a formula that takes into account five criteria: the number of breeding animals or breeding females; the percentage of pure-bred matings; the five-year trend in breed numbers; the number of breeders or herds; and the interval between generations of the animal. [ 5 ]
The GEH also publishes, in conjunction with the Bund Deutscher Rassegeflügelzüchter [ de ] , the German national association of poultry breeders, a separate list of the historic poultry breeds and colour varieties that were raised in Germany before 1930. The same levels of conservation risk are assigned as in the main red list. [ 6 ]
Since 1984 the GEH has each year named one or more animal breeds as "endangered breed of the year". To date, these have been: [ 7 ] | https://en.wikipedia.org/wiki/Gesellschaft_zur_Erhaltung_alter_und_gefährdeter_Haustierrassen |
Gestalt pattern matching , [ 1 ] also Ratcliff/Obershelp pattern recognition , [ 2 ] is a string-matching algorithm for determining the similarity of two strings . It was developed in 1983 by John W. Ratcliff and John A. Obershelp and published in the Dr. Dobb's Journal in July 1988. [ 2 ]
The similarity of two strings S 1 {\displaystyle S_{1}} and S 2 {\displaystyle S_{2}} is determined by this formula: twice the number of matching characters K m {\displaystyle K_{m}} divided by the total number of characters of both strings. The matching characters are defined as some longest common substring [ 3 ] plus recursively the number of matching characters in the non-matching regions on both sides of the longest common substring: [ 2 ] [ 4 ]
where the similarity metric can take a value between zero and one:
The value of 1 stands for the complete match of the two strings, whereas the value of 0 means there is no match and not even one common letter.
The longest common substring is WIKIM (light grey) with 5 characters. There is no further substring on the left. The non-matching substrings on the right side are EDIA and ANIA . They again have a longest common substring IA (dark gray) with length 2.
The similarity metric is determined by:
The Ratcliff/Obershelp matching characters can be substantially different from each longest common subsequence of the given strings. For example S 1 = q c c c c c r d d d s b b b b t e e e u {\displaystyle S_{1}=q\;ccccc\;r\;ddd\;s\;bbbb\;t\;eee\;u} and S 2 = v d d d w b b b b x e e e y c c c c c z {\displaystyle S_{2}=v\;ddd\;w\;bbbb\;x\;eee\;y\;ccccc\;z} have c c c c c {\displaystyle ccccc} as their only longest common substring, and no common characters right of its occurrence, and likewise left, leading to K m = 5 {\displaystyle K_{m}=5} . However, the longest common subsequence of S 1 {\displaystyle S_{1}} and S 2 {\displaystyle S_{2}} is ( d d d ) ( b b b b ) ( e e e ) {\displaystyle (ddd)\;(bbbb)\;(eee)} , with a total length of 10 {\displaystyle 10} .
The execution time of the algorithm is O ( n 3 ) {\displaystyle O(n^{3})} in a worst case and O ( n 2 ) {\displaystyle O(n^{2})} in an average case. By changing the computing method, the execution time can be improved significantly. [ 1 ]
The Python library implementation of the gestalt pattern matching algorithm is not commutative : [ 5 ]
For the two strings
and
the metric result for
The Python difflib library, which was introduced in version 2.1, [ 1 ] implements a similar algorithm that predates the Ratcliff-Obershelp algorithm. Due to the unfavourable runtime behaviour of this similarity metric, three methods have been implemented. Two of them return an upper bound in a faster execution time. [ 1 ] The fastest variant only compares the length of the two substrings: [ 6 ]
The second upper bound calculates twice the sum of all used characters S 1 {\displaystyle S_{1}} which occur in S 2 {\displaystyle S_{2}} divided by the length of both strings but the sequence is ignored.
Trivially the following applies: | https://en.wikipedia.org/wiki/Gestalt_pattern_matching |
Gestonorone caproate , also known as gestronol hexanoate or norhydroxyprogesterone caproate and sold under the brand names Depostat and Primostat , is a progestin medication which is used in the treatment of enlarged prostate and cancer of the endometrium . [ 5 ] [ 3 ] [ 7 ] [ 1 ] [ 8 ] It is given by injection into muscle typically once a week. [ 4 ]
Side effects of gestonorone caproate include worsened glucose tolerance , decreased libido in men, and injection site reactions . [ 5 ] Gestonorone caproate is a progestin, or a synthetic progestogen , and hence is an agonist of the progesterone receptor , the biological target of progestogens like progesterone . [ 9 ] [ 10 ] It has no other important hormonal activity. [ 5 ] [ 11 ] [ 12 ] [ 13 ]
Gestonorone caproate was discovered in 1960 and was introduced for medical use by 1973. [ 14 ] [ 15 ] It has been used widely throughout Europe , including in the United Kingdom , and has also been marketed in certain other countries such as Japan , China , and Mexico . [ 1 ] [ 16 ] [ 17 ] [ 18 ] However, it has since mostly been discontinued, and it remains available today only in a handful of countries, including the Czech Republic , Japan, Mexico, and Russia . [ 18 ] [ 19 ]
Gestonorone caproate is used in the palliative treatment of benign prostatic hyperplasia and endometrial cancer . [ 5 ] [ 3 ] [ 20 ] It is used at a dose of 100 to 200 mg once a week by intramuscular injection . [ 5 ]
Side effects of gestonorone caproate have been reported to include worsened glucose tolerance , decreased libido in men, and local injection site reactions such as irritation . [ 5 ]
Gestonorone caproate is a potent , long-acting, and pure progestogen , [ 9 ] [ 10 ] [ 13 ] possessing no androgenic , anabolic , antiandrogenic , estrogenic , antiestrogenic , glucocorticoid , mineralocorticoid , or teratogenic effects. [ 5 ] [ 11 ] [ 12 ] [ 13 ] [ 21 ] It is approximately 20 to 25 times more potent than progesterone or hydroxyprogesterone caproate in animal bioassays when all are given by subcutaneous injection . [ 5 ] [ 13 ] [ 22 ] In humans, 100 or 200 mg intramuscular gestonorone caproate has been said to be equivalent to 1,000 mg intramuscular hydroxyprogesterone caproate. [ 23 ] [ 24 ] Hence, gestonorone caproate is approximately 5- to 10-fold more potent than hydroxyprogesterone caproate in humans. [ 11 ] [ 23 ] [ 24 ] The biological effects of gestonorone caproate in women have been studied. [ 25 ] [ 26 ]
Like other potent progestins, gestonorone caproate possesses potent antigonadotropic activity and is capable of markedly suppressing the gonadal production and circulating levels of sex hormones such as testosterone and estradiol . [ 13 ] [ 27 ] [ 28 ] A clinical study found that 400 mg/week intramuscular gestonorone caproate suppressed testosterone levels by 75% in men, while orchiectomy as a comparator reduced testosterone levels by 91%. [ 29 ] [ 30 ] Levels of luteinizing hormone , conversely, remained unchanged. [ 29 ] In general, progestogens can maximally suppress testosterone levels by about 70 to 80%. [ 31 ] [ 32 ] [ 33 ] [ 29 ] [ 30 ] In accordance with its lack of glucocorticoid activity, gestonorone caproate has no anticorticotropic effects, and does not influence the secretion of adrenocorticotropic hormone . [ 5 ]
17α-Hydroxyprogesterone has weak progestogenic activity, but C17α esterification results in higher progestogenic activity. [ 6 ] Of a variety of different esters , the caproate (hexanoate) ester was found to have the strongest progestogenic activity, and this formed the basis for the development of gestonorone caproate, as well as other caproate progestogen esters such as hydroxyprogesterone caproate. [ 6 ]
Gestonorone caproate has been found to decrease the weights of the prostate gland and seminal vesicles by 40 to 70% in adult male rats. [ 5 ] It has been shown in canines to mediate these effects both via its antigonadotropic effects and by direct actions in these tissues. [ 5 ] Gestonorone caproate decreases the uptake of testosterone into the prostate gland. [ 5 ] It has also been found to have direct antiproliferative effects on human ovarian cancer cells in vitro . [ 5 ]
Gestonorone caproate has been reported to act to some extent as a 5α-reductase inhibitor , similarly to progesterone. [ 34 ] [ 35 ]
Like the closely related progestins hydroxyprogesterone caproate and 19-norprogesterone , gestonorone caproate shows poor activity orally and must be administered parenterally ; specifically, via intramuscular injection . [ 4 ] Gestonorone caproate is administered by intramuscular injection, and acts as a long-lasting depot by this route. [ 5 ] [ 55 ] [ 56 ] [ 57 ] After an intramuscular injection, gestonorone caproate is completely released from the local depot and is highly bioavailable . [ 5 ] A single intramuscular injection of 25 to 50 mg gestonorone caproate in oil solution has been found to have a duration of action of 8 to 13 days in terms of clinical biological effect in the uterus in women. [ 26 ] [ 58 ] [ 59 ] At high doses, the duration of action of gestonorone caproate by intramuscular injection has been found to be at least 21 days. [ 5 ] Clinical studies have found gestonorone caproate to be satisfactorily effective as a progestogen when injected once a month, whereas it was poorly effective as an injectable contraceptive when it was injected once every two months. [ 60 ] [ 61 ]
Following a single intramuscular injection of 200 mg radiolabeled gestonorone caproate in 1 mL of solution in men with prostate cancer, maximal levels of gestonorone caproate occurred after 3 ± 1 days and were 420 ± 160 ng/mL. [ 5 ] The elimination half-life of gestonorone caproate and its metabolites was 7.5 ± 3.1 days. [ 5 ] Approximately 5% of the radioactive steroid content in the blood was unchanged gestonorone caproate. [ 5 ] No free gestonorone was observed in circulation or in urine . [ 5 ] Gestonorone caproate and its metabolites were eliminated 72% in feces and 28% in urine . [ 5 ] [ 62 ] Approximately 48 ± 18% of the injected dose had been eliminated after 14 days and approximately 85 ± 12% of the injected dose had been excreted after 30 days. [ 5 ]
The metabolism of unesterified gestonorone (17α-hydroxy-19-norprogesterone) is analogous to that of 17α-hydroxyprogesterone , with the corresponding 19-norpregnane metabolites produced. [ 6 ] Gestonorone caproate has been found to undergo 5α-reduction similarly to progesterone , 17α-hydroxyprogesterone, and gestonorone, and at a similar rate as these steroids . [ 6 ] Conversely however, due to its caproate ester, 5β-reduction of gestonorone caproate is decreased relative to these steroids. [ 6 ] As progesterone is metabolized mainly into 5β-pregnanes , decreased 5β-reduction of gestonorone caproate may be involved in its greater potency compared to progesterone. [ 6 ] The major metabolites of gestonorone caproate have been reported to be isomers of 19-norpregnanetriol and 19-norpregnanediol-20-one. [ 6 ] [ 21 ] These metabolites indicate that gestonorone caproate is metabolized mainly by reduction at the C3, C5, and C20 positions. [ 6 ] Following an intramuscular injection of 300 mg gestonorone caproate, only a slight increase in urinary pregnanetriol excretion has been observed. [ 6 ] Cleavage of the caproate ester of gestonorone caproate is minimal, which indicates that it is not a prodrug of the unesterified steroid. [ 6 ]
Gestonorone caproate, also known as norhydroxyprogesterone caproate, 17α-hydroxy-19-norprogesterone 17α-hexanoate, or 17α-hydroxy-19-norpregn-4-ene-3,20-dione 17α-hexanoate, is a synthetic norpregnane steroid and a derivative of progesterone . [ 63 ] [ 16 ] It is specifically a combined derivative of 17α-hydroxyprogesterone and 19-norprogesterone , or of gestronol (17α-hydroxy-19-norprogesterone), with a hexanoate (caproate) ester at the C17α position. [ 63 ] [ 16 ] Analogues and derivatives of gestonorone caproate include algestone acetophenide (dihydroxyprogesterone acetophenide), demegestone , nomegestrol acetate , norgestomet , and segesterone acetate , as well as 18-methylsegesterone acetate and the caproate esters chlormadinone caproate , hydroxyprogesterone caproate , medroxyprogesterone caproate , megestrol caproate , and methenmadinone caproate . [ 63 ] [ 16 ]
Chemical syntheses of gestonorone caproate have been published. [ 5 ] [ 7 ] [ 64 ]
Gestonorone caproate was first described in 1960. [ 14 ] It was developed by Schering and has been marketed since at least 1968. [ 12 ] [ 15 ]
Gestonorone caproate is the generic name of the drug and its INN Tooltip International Nonproprietary Name , USAN Tooltip United States Adopted Name , and JAN Tooltip Japanese Accepted Name , while gestronol hexanoate is its BANM Tooltip British Approved Name . [ 63 ] [ 16 ] It has also been referred to as norhydroxyprogesterone caproate , and is also known by its former developmental code names SH-582 and SH-80582 . [ 63 ] [ 16 ] [ 17 ]
Gestonorone caproate has been marketed exclusively under the brand names Depostat and Primostat. [ 63 ] [ 16 ] [ 17 ] [ 18 ] [ 19 ]
Gestonorone caproate has been available widely in Europe , including in the United Kingdom , and has also been marketed in Japan , China , Mexico , and certain other countries. [ 1 ] [ 16 ] [ 17 ] [ 18 ] However, it has been discontinued in most countries and its availability is more limited today; it appears to remain marketed only in the Czech Republic , Japan, Mexico, and Russia . [ 18 ] [ 19 ] [ 65 ] It has not been marketed in the United States , Canada , and many other countries. [ 16 ] [ 17 ] [ 18 ] [ 19 ]
Gestonorone caproate was studied in the treatment of prostate cancer in men at a dosage of 400 mg per week by intramuscular injection but, in contrast to the case of benign prostatic hyperplasia , was found to be ineffective. [ 66 ] [ 67 ]
SH-834 was a combination of 90 mg estradiol valerate and 300 mg gestonorone caproate for weekly intramuscular injection that was developed by Schering in the 1960s and 1970s. [ 68 ] [ 22 ] [ 69 ] It was investigated clinically as a treatment for breast cancer and was found to be effective. [ 68 ] [ 70 ] [ 69 ] However, its effectiveness was found to be no better than that of an estrogen alone, and the combination was ultimately never marketed. [ 71 ]
Gestonorone caproate was studied by Schering for use as a progestogen-only injectable contraceptive across a dose range of 2.5 to 200 mg once every one or two months but was never marketed. [ 61 ] [ 72 ] [ 73 ] [ 74 ] [ 75 ] [ 76 ] [ 77 ] [ 78 ] There is very little clinical experience of gestonorone caproate for this indication. [ 61 ]
Gestonorone caproate has been studied in the treatment of ovarian cancer (in combination with cyclophosphamide ), [ 5 ] [ 22 ] [ 79 ] [ 80 ] menstrual cycle -related mouth ulcers , [ 21 ] and as a component of menopausal hormone therapy . [ 60 ] | https://en.wikipedia.org/wiki/Gestonorone_caproate |
The " Get a Mac " campaign was a television advertising campaign created for Apple Inc. (Apple Computer, Inc. at the start of the campaign) by TBWA\Media Arts Lab , the company's advertising agency, that ran from 2006 to 2009. [ 1 ] [ 2 ] The advertising campaign ran in the United States, Canada, Australia, New Zealand, the United Kingdom, Japan, and Germany.
The Get a Mac advertisements follow a standard template. They open to a plain white background, and a man dressed in casual clothes introduces himself as an Apple Mac computer ("Hello, I'm a Mac."), while a man in a more formal suit-and-tie combination introduces himself as a Microsoft Windows personal computer ("And I'm a PC .").
The two then act out a brief vignette , in which the capabilities and attributes of Mac and PC are compared, with PC—characterized as formal and somewhat polite, though uninteresting and overly concerned with work—often being frustrated by the more laid-back Mac's abilities. The commercials end with a still shot of a Mac desktop or laptop displaying the Mac logo on its screen. The earlier commercials in the campaign involved a general comparison of the two computers, whereas the later ones mainly concerned Windows Vista and Windows 7 .
The original American advertisements star actor Justin Long as the Mac, and author and humorist John Hodgman as the PC, and were directed by Phil Morrison . The American advertisements also aired on Canadian, Australian, and New Zealand television, [ citation needed ] and at least 24 of them were dubbed into Spanish, French, German, and Italian. The British campaign stars comedic duo Robert Webb as Mac and David Mitchell as PC, while the Japanese campaign features the comedic duo Rahmens . Several of the British and Japanese advertisements, although based on the originals, were slightly altered to better target the new audiences. Both the British and Japanese campaigns also feature several original ads not seen in the American campaign. [ citation needed ]
The Get a Mac campaign is the successor to the Switch ads which were first broadcast in 2002. Both campaigns were filmed against a plain white background. Apple's former CEO , Steve Jobs , introduced the campaign during a shareholder's meeting the week before the campaign started. The campaign also coincided with a change of signage and employee apparel at Apple retail stores detailing reasons to switch to Macs.
The Get a Mac campaign received the Grand Effie Award in 2007. [ 3 ]
The advertisements play on perceived weaknesses of non-Mac personal computers , especially those running Microsoft Windows , of which PC is clearly intended to be a parody, and corresponding strengths possessed by the Mac OS (such as immunity to circulating viruses and spyware targeted at Microsoft Windows). The target audience of these ads is not devoted PC users, but rather those who are more likely to "swing" towards Apple. Apple realized that many consumers who chose PCs did so because of their lack of knowledge of the Apple brand. With this campaign, Apple was targeting those users who may not consider Macs when purchasing but may be persuaded to when they view these ads. [ 4 ] Each of the ads is about 30 seconds in length and is accompanied by a song called "Having Trouble Sneezing", which was composed by Mark Mothersbaugh .
The following is an alphabetical list of the ads that appeared in the campaign shown in the United States, Canada, [ 5 ] Australia and New Zealand.
Several advertisements have been shown exclusively in Flash ad campaigns running on numerous websites. [ 6 ] Unlike the ads shown on television, these advertisements have not been posted as high-quality QuickTime videos on Apple's website. These ads run for approximately 20 seconds each and reference specific online advertising features (such as banner ads ), making it unlikely they will ever appear on television.
The titles are taken from the Flash-video file names.
For the British market, the ads were recast with the popular British comedy double act Mitchell and Webb in the lead roles; David Mitchell as PC and Robert Webb as Mac. As well as original ads, several ads from the American campaign were reshot with new dialogue and slightly altered scenes. These ads are about 40 seconds long, which is slightly longer than the US advertisements.
The following ads are exclusive to the UK:
Several American ads were modified for the UK market. In some of these ads, the events that occur in the narrative differ significantly from the original American campaign. Others follow the original ads more closely, with only minor differences (many based on the differences in characterization from the actors involved or language differences between American English and British English ). These ads are also performed by Mitchell and Webb.
The adapted ads are
On December 12, 2006, Apple began to release ads in Japan that were similar in style to the US Get a Mac ads. The Mac and PC are played by the Rahmens , a Japanese comedy duo. The ads used to be viewable at Apple's Japan website.
The following ads are exclusive to Japan:
Several American ads were modified for the Japanese market. In some of these ads, the events that occur in the narrative differ significantly from the original American campaign. Others follow the original ads more closely, with only minor differences (many based on the differences in characterization from the actors involved).
The adapted ads are
While not strictly a part of the ad campaign, Hodgman and Long appeared in videos during Steve Jobs 's keynote addresses at the 2006, 2007, and 2009 Worldwide Developers Conference and the 2008 MacWorld Expo . Hodgman alone appeared in the November 2020 Apple Event.
Before the campaign's launch, Apple had seen lower sales in 2005–06. One month after the start of the "Get a Mac" campaign, Apple saw an increase of 200,000 Macs sold, and at the end of July 2006, Apple announced that it had sold 1.3 million Macs. Apple had an overall increase in sales of 39% for the fiscal year ending September 2006. [ 4 ]
In an article for Slate magazine, Seth Stevenson criticized the campaign as being too "mean spirited", suggesting, "isn't smug superiority (no matter how affable and casually dressed) a bit off-putting as a brand strategy?". [ 13 ]
Writing in The Guardian , Charlie Brooker criticized the casting of comedians Mitchell and Webb in the UK campaign, noting that in the sitcom they were then starring in together, Peep Show , "Mitchell plays a repressed, neurotic underdog, and Webb plays a selfish, self-regarding poseur... So when you see the ads, you think, 'PCs are a bit rubbish yet ultimately lovable, whereas Macs are just smug, preening tossers.'" [ 14 ]
PC Magazine Editor in Chief Lance Ulanoff criticized the campaign's use of the term "PC" to refer specifically to IBM PC compatible , or Wintel , computers, noting that this usage, though common, is incorrect, as the Macintosh is also a personal computer . In a 2008 column, he recommended that the characters instead introduce themselves as "a Mac PC" and "a Windows PC", adding, "Of course, the ads would then be far less effective, because consumers might realize that the differences Apple is trying to tout aren't quite as huge as Apple would like you to believe." [ 15 ]
Microsoft responded to the Get a Mac advertising campaign in late 2008 by releasing the I'm a PC campaign, featuring Microsoft employee Sean Siler as a John Hodgman look-alike. While Apple's ads show personifications of both Mac and PC systems, the Microsoft ads show PC users instead proudly defining themselves as PCs.
In the wake of the Mac transition to Apple silicon , in March 2021, Intel made a similar advertising campaign, known as Justin Gets Real, featuring Justin Long as himself promoting Intel PCs over Macs. These commercials typically start with Long stating, "Hello, I'm a..." against the familiar plain white background before he suddenly says, "Justin, just a real person doing a real comparison between Mac and PC.". He is then seen interacting with the computers in a realistic setting and/or with others using them. [ 22 ] [ 23 ] | https://en.wikipedia.org/wiki/Get_a_Mac |
The Gewald reaction (or the Gewald aminothiophene synthesis) is an organic reaction involving the condensation of a ketone (or aldehyde when R 2 = H) with a α-cyanoester in the presence of elemental sulfur and base to give a poly-substituted 2-amino- thiophene . [ 1 ] [ 2 ]
The reaction is named after the German chemist Karl Gewald [ de ] . [ 3 ] [ 4 ] [ 5 ]
The reaction mechanism of the Gewald reaction was elucidated 30 years after the reaction was discovered. [ 6 ] The first step is a Knoevenagel condensation between the ketone ( 1 ) and the α-cyanoester ( 2 ) to produce the stable intermediate 3 . The mechanism of the addition of the elemental sulfur is unknown. It is postulated to proceed through intermediate 4 . Cyclization and tautomerization will produce the desired product ( 6 ).
Microwave irradiation has been shown beneficial to reaction yields and times. [ 7 ]
In one variation of the Gewald reaction a 3-acetyl-2-aminothiophene is synthesized starting from a dithiane (an adduct of sulfur and acetone if R = CH 3 or acetaldehyde if R = H) and the sodium salt of cyanoacetone which in itself is very unstable: [ 8 ]
Media related to Gewald reaction at Wikimedia Commons | https://en.wikipedia.org/wiki/Gewald_reaction |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.