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the universe then becomes lim z → ∞ d T ( z ) / c {\displaystyle \lim _{z\to \infty }d_{T}(z)/c} , and the time elapsed since redshift z {\displaystyle z} until now is: t ( z ) = d T ( z ) / c . {\displaystyle t(z)=d_{T}(z)/c.} === Etherington's distance duality === The Etherington's distance-duality equation is the relationship between the luminosity distance of standard candles and the angular-diameter distance. It is expressed as follows: d L = ( 1 + z ) 2 d A {\displaystyle d_{L}=(1+z)^{2}d_{A}} == See also == Big Bang Comoving and proper distances Friedmann equations Parsec Physical cosmology Cosmic distance ladder Friedmann–Lemaître–Robertson–Walker metric Subatomic scale == References == Scott Dodelson, Modern Cosmology. Academic Press (2003). == External links == 'The Distance Scale of the Universe' compares different cosmological distance measures. 'Distance measures in cosmology' explains in detail how to calculate the different distance measures as a function of world model and redshift. iCosmos: Cosmology Calculator (With Graph Generation ) calculates the different distance measures as a function of cosmological model and redshift, and generates plots for the model from redshift 0 to 20.
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"page_id": 8065677,
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"title": "Distance measure"
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Lamé's stress ellipsoid is an alternative to Mohr's circle for the graphical representation of the stress state at a point. The surface of the ellipsoid represents the locus of the endpoints of all stress vectors acting on all planes passing through a given point in the continuum body. In other words, the endpoints of all stress vectors at a given point in the continuum body lie on the stress ellipsoid surface, i.e., the radius-vector from the center of the ellipsoid, located at the material point in consideration, to a point on the surface of the ellipsoid is equal to the stress vector on some plane passing through the point. In two dimensions, the surface is represented by an ellipse. Once the equations of the ellipsoid is known, the magnitude of the stress vector can then be obtained for any plane passing through that point. To determine the equation of the stress ellipsoid we consider the coordinate axes x 1 , x 2 , x 3 {\displaystyle x_{1},x_{2},x_{3}\,\!} taken in the directions of the principal axes, i.e., in a principal stress space. Thus, the coordinates of the stress vector T ( n ) {\displaystyle \mathbf {T} ^{(\mathbf {n} )}\,\!} on a plane with normal unit vector n {\displaystyle \mathbf {n} \,\!} passing through a given point P {\displaystyle P\,\!} is represented by T 1 ( n ) = σ 1 n 1 , T 2 ( n ) = σ 2 n 2 , T 3 ( n ) = σ 3 n 3 {\displaystyle T_{1}^{(\mathbf {n} )}=\sigma _{1}n_{1},\qquad T_{2}^{(\mathbf {n} )}=\sigma _{2}n_{2},\qquad T_{3}^{(\mathbf {n} )}=\sigma _{3}n_{3}\,} And knowing that n {\displaystyle \mathbf {n} \,\!} is a unit vector we have n 1 2 + n 2 2 + n 3 2 = T 1 2 σ 1 2 + T
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"page_id": 27071123,
"source": null,
"title": "Lamé's stress ellipsoid"
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2 2 σ 2 2 + T 3 2 σ 3 2 = 1 {\displaystyle n_{1}^{2}+n_{2}^{2}+n_{3}^{2}={\frac {T_{1}^{2}}{\sigma _{1}^{2}}}+{\frac {T_{2}^{2}}{\sigma _{2}^{2}}}+{\frac {T_{3}^{2}}{\sigma _{3}^{2}}}=1\,} which is the equation of an ellipsoid centered at the origin of the coordinate system, with the lengths of the semiaxes of the ellipsoid equal to the magnitudes of the principal stresses, i.e. the intercepts of the ellipsoid with the principal axes are ± σ 1 , ± σ 2 , ± σ 3 {\displaystyle \pm \sigma _{1},\pm \sigma _{2},\pm \sigma _{3}\,\!} . The first stress invariant I 1 {\displaystyle I_{1}\,\!} is directly proportional to the sum of the principal radii of the ellipsoid. The second stress invariant I 2 {\displaystyle I_{2}\,\!} is directly proportional to the sum of the three principal areas of the ellipsoid. The three principal areas are the ellipses on each principal plane. The third stress invariant I 3 {\displaystyle I_{3}\,\!} is directly proportional to the volume of the ellipsoid. If two of the three principal stresses are numerically equal the stress ellipsoid becomes an ellipsoid of revolution. Thus, two principal areas are ellipses and the third is a circle. If all of the principal stresses are equal and of the same sign, the stress ellipsoid becomes a sphere and any three perpendicular directions can be taken as principal axes. The stress ellipsoid by itself, however, does not indicate the plane on which the given traction vector acts. Only for the case where the stress vector lies along one of the principal directions it is possible to know the direction of the plane, as the principal stresses act perpendicular to their planes. To find the orientation of any other plane we used the stress-director surface or stress director quadric represented by the equation x 1 2 σ 1 + x 2 2 σ 2
|
{
"page_id": 27071123,
"source": null,
"title": "Lamé's stress ellipsoid"
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+ x 3 2 σ 3 = 1 {\displaystyle {\frac {x_{1}^{2}}{\sigma _{1}}}+{\frac {x_{2}^{2}}{\sigma _{2}}}+{\frac {x_{3}^{2}}{\sigma _{3}}}=1} The stress represented by a radius-vector of the stress ellipsoid acts on a plane oriented parallel to the tangent plane to the stress-director surface at the point of its intersection with the radius-vector. == References == == Bibliography == Timoshenko, Stephen P.; James Norman Goodier (1970). Theory of Elasticity (Third ed.). McGraw-Hill International Editions. ISBN 0-07-085805-5. Timoshenko, Stephen P. (1983). History of strength of materials: with a brief account of the history of theory of elasticity and theory of structures. Dover Books on Physics. Dover Publications. ISBN 0-486-61187-6.
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"page_id": 27071123,
"source": null,
"title": "Lamé's stress ellipsoid"
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A bestiary (Latin: bestiarium vocabulum) is a compendium of beasts. Originating in the ancient world, bestiaries were made popular in the Middle Ages in illustrated volumes that described various animals and even rocks. The natural history and illustration of each beast was usually accompanied by a moral lesson. This reflected the belief that the world itself was the Word of God and that every living thing had its own special meaning. For example, the pelican, which was believed to tear open its breast to bring its young to life with its own blood, was a living representation of Jesus. Thus the bestiary is also a reference to the symbolic language of animals in Western Christian art and literature. == History == The bestiary — the medieval book of beasts — was among the most popular illuminated texts in northern Europe during the Middle Ages (about 500–1500). Medieval Christians understood every element of the world as a manifestation of God, and bestiaries largely focused on each animal's religious meaning. Much of what is in the bestiary came from the ancient Greeks and their philosophers. The earliest bestiary in the form in which it was later popularized was an anonymous 2nd-century Greek volume called the Physiologus, which itself summarized ancient knowledge and wisdom about animals in the writings of classical authors such as Aristotle's Historia Animalium and various works by Herodotus, Pliny the Elder, Solinus, Aelian and other naturalists. Following the Physiologus, Saint Isidore of Seville (Book XII of the Etymologiae) and Saint Ambrose expanded the religious message with reference to passages from the Bible and the Septuagint. They and other authors freely expanded or modified pre-existing models, constantly refining the moral content without interest in or access to much more detail regarding the factual content. Nevertheless, the often fanciful accounts of
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"page_id": 4757,
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these beasts were widely read and generally believed to be true. A few observations found in bestiaries, such as the migration of birds, were discounted by the natural philosophers of later centuries, only to be rediscovered in the modern scientific era. Medieval bestiaries are remarkably similar in sequence of the animals of which they treat. Bestiaries were particularly popular in England and France around the 12th century and were mainly compilations of earlier texts. The Aberdeen Bestiary is one of the best known of over 50 manuscript bestiaries surviving today. Much influence comes from the Renaissance era and the general Middle Ages, as well as modern times. The Renaissance has been said to have started around the 14th century in Italy. Bestiaries influenced early heraldry in the Middle Ages, giving ideas for charges and also for the artistic form. Bestiaries continue to give inspiration to coats of arms created in our time. Two illuminated Psalters, the Queen Mary Psalter (British Library Ms. Royal 2B, vii) and the Isabella Psalter (State Library, Munich), contain full Bestiary cycles. The bestiary in the Queen Mary Psalter is found in the "marginal" decorations that occupy about the bottom quarter of the page, and are unusually extensive and coherent in this work. In fact the bestiary has been expanded beyond the source in the Norman bestiary of Guillaume le Clerc to ninety animals. Some are placed in the text to make correspondences with the psalm they are illustrating. Many decide to make their own bestiary with their own observations including knowledge from previous ones. These observations can be made in text form, as well as illustrated out. The Italian artist Leonardo da Vinci also made his own bestiary. A volucrary is a similar collection of the symbols of birds that is sometimes found in conjunction
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"page_id": 4757,
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"title": "Bestiary"
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with bestiaries. The most widely known volucrary in the Renaissance was Johannes de Cuba's Gart der Gesundheit which describes 122 birds and which was printed in 1485. == Bestiary content == The contents of medieval bestiaries were often obtained and created from combining older textual sources and accounts of animals, such as the Physiologus. Medieval bestiaries contained detailed descriptions and illustrations of species native to Western Europe, exotic animals and what in modern times are considered to be imaginary animals. Descriptions of the animals included the physical characteristics associated with the creature, although these were often physiologically incorrect, along with the Christian morals that the animal represented. The description was then often accompanied by an artistic illustration of the animal as described in the bestiary. For example, in one bestiary the eagle is depicted in an illustration and is said to be the “king of birds.” Bestiaries were organized in different ways based upon the sources they drew upon. The descriptions could be organized by animal groupings, such as terrestrial and marine creatures, or presented in an alphabetical manner. However, the texts gave no distinction between existing and imaginary animals. Descriptions of creatures such as dragons, unicorns, basilisk, griffin and caladrius were common in such works and found intermingled amongst accounts of bears, boars, deer, lions, and elephants. In one source, the author explains how fables and bestiaries are closely linked to one another as “each chapter of a bestiary, each fable in a collection, has a text and has a meaning. This lack of separation has often been associated with the assumption that people during this time believed in what the modern period classifies as nonexistent or "imaginary creatures". However, this assumption is currently under debate, with various explanations being offered. Some scholars, such as Pamela Gravestock, have written
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"page_id": 4757,
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"title": "Bestiary"
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on the theory that medieval people did not actually think such creatures existed but instead focused on the belief in the importance of the Christian morals these creatures represented, and that the importance of the moral did not change regardless if the animal existed or not. The historian of science David C. Lindberg pointed out that medieval bestiaries were rich in symbolism and allegory, so as to teach moral lessons and entertain, rather than to convey knowledge of the natural world. == Religious significance == The significance shown between animals and religion started much before bestiaries came into play. In many ancient civilizations there are references to animals and their meaning within that specific religion or mythology that we know of today. These civilizations included Egypt and their gods with the faces of animals or Greece which had symbolic animals for their godly beings, an example being Zeus and the eagle. With animals being a part of religion before bestiaries and their lessons came out, they were influenced by past observations of meaning as well as older civilizations and their interpretations. As most of the students who read these bestiaries were monks and clerics, it is not impossible to say that there is a major religious significance within them. The bestiary was used to educate young men on the correct morals they should display. All of the animals presented in the bestiaries show some sort of lesson or meaning when presented. Much of the symbolism shown of animals. Much of what is proposed by the bestiaries mentions much of paganism because of the religious significance and time period of the medieval ages. One of the main 'animals' mentioned in some of the bestiaries is dragons, which hold much significance in terms of religion and meaning. The unnatural part of dragon's
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"page_id": 4757,
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history shows how important the church can be during this time. Much of what is covered in the article talks about how the dragon that is mentioned in some of the bestiaries shows a glimpse of the religious significance in many of these tales. These bestiaries held much content in terms of religious significance. In almost every animal there is some way to connect it to a lesson from the church or a familiar religious story. With animals holding significance since ancient times, it is fair to say that bestiaries and their contents gave fuel to the context behind the animals, whether real or myth, and their meanings. == Modern bestiaries == In modern times, artists such as Henri de Toulouse-Lautrec and Saul Steinberg have produced their own bestiaries. Jorge Luis Borges wrote a contemporary bestiary of sorts, the Book of Imaginary Beings, which collects imaginary beasts from bestiaries and fiction. Nicholas Christopher wrote a literary novel called "The Bestiary" (Dial, 2007) that describes a lonely young man's efforts to track down the world's most complete bestiary. John Henry Fleming's Fearsome Creatures of Florida (Pocol Press, 2009) borrows from the medieval bestiary tradition to impart moral lessons about the environment. Caspar Henderson's The Book of Barely Imagined Beings (Granta 2012, University of Chicago Press 2013), subtitled "A 21st Century Bestiary", explores how humans imagine animals in a time of rapid environmental change. In July 2014, Jonathan Scott wrote The Blessed Book of Beasts, Eastern Christian Publications, featuring 101 animals from the various translations of the Bible, in keeping with the tradition of the bestiary found in the writings of the Saints, including Saint John Chrysostom. In today's world there is a discipline called cryptozoology which is the study of unknown species. This discipline can be linked to medieval bestiaries because
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{
"page_id": 4757,
"source": null,
"title": "Bestiary"
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in many cases the unknown animals can be the same, as well as having meaning or significance behind them. The lists of monsters to be found in video games (such as NetHack, Dragon Quest, and Monster Hunter), as well as some tabletop role-playing games such as Pathfinder, are often termed bestiaries. == See also == Allegory in the Middle Ages List of medieval bestiaries Marine counterparts of land creatures Animal representation in Western medieval art == References == == Notes == == External links == The Bestiary: The Book of Beasts, T.H. White's translation of a medieval bestiary in the Cambridge University library; digitized by the University of Wisconsin–Madison libraries. The Medieval Bestiary online, edited by David Badke. The Bestiaire of Philippe de Thaon at the National Library of Denmark. The Bestiary of Anne Walshe at the National Library of Denmark. The Aberdeen Bestiary at the University of Aberdeen. Exhibition (in English, but French version is fuller) at the Bibliothèque nationale de France Christian Symbology Animals and their meanings in Christian texts. Bestiairy - Monsters & Fabulous Creatures of Greek Myth & Legend with pictures
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"page_id": 4757,
"source": null,
"title": "Bestiary"
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András Kornai (born 1957 in Budapest), son of economist János Kornai, is a mathematical linguist. He has earned two PhDs. He earned his first in Mathematics in 1983 from Eötvös Loránd University in Budapest, where his advisor was Miklós Ajtai, and his second in Linguistics in 1991 from Stanford University, where his advisor was Paul Kiparsky. He is a professor in the Department of Algebra at the Budapest Institute of Technology, where he works on an open source Hungarian morphological analyzer. He was Chief Scientist at MetaCarta, where he worked on information extraction before the company was acquired by Nokia. Prior to MetaCarta, he was Chief Scientist at Northern Light. He is on the board of the journal Grammars and YourAmigo PLC. His research interests include all mathematical aspects of natural language processing, speech recognition, and OCR. As Area Editor he was responsible for the Mathematical Linguistics area of the Oxford International Encyclopedia of Linguistics, and his joint work with Geoffrey Pullum, "The X-bar Theory of Phrase Structure", formally reconstructed that then-popular linguistic theory. == Monographs == Semantics. Springer Nature, 2020. ISBN 978-3-319-65644-1 Mathematical Linguistics. Springer Verlag, in the series Advanced Information and Knowledge Processing, November 2007. ISBN 978-1-84628-985-9 Hardbound, approximately 300 pages. See description. Formal Phonology. In the series Outstanding Dissertations in Linguistics, Garland Publishing, 1994, ISBN 0-8153-1730-1, hardbound, 240 pages Contents, Preface, Introduction (20 pages) On Hungarian Morphology. In the series Linguistica, Hungarian Academy of Sciences, 1994, ISBN 963-8461-73-X, paperbound, 174 pages Contents, Preface, Introduction (10 pages) == Books edited == Oxford International Encyclopedia of Linguistics (Mathematical Linguistics Area Editor under Editor in Chief William Frawley). 4 volumes, Oxford University Press, 2003, ISBN 978-0-19-513977-8. Proceedings of the HLT-NAACL Workshop on the Analysis of Geographic References. Jointly with Beth Sundheim. Association for Computational Linguistics, 2003, ISBN 1-932432-04-3 (WS9), paperbound,
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"page_id": 6558358,
"source": null,
"title": "András Kornai"
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vi+81 pages. See related material. Extended Finite State Models of Language (editor). In the series Studies in Natural Language Processing, Cambridge University Press, 1999, ISBN 0-521-63198-X, hardbound, x+278 pages Contents, Introduction (7 pages). == Selected papers == Digital Language Death. PLoS ONE 8(10): e77056, 2012. [1] Hunmorph: open source word analysis (Jointly with V. Tron, Gy. Gyepesi, P. Halacsy, L. Nemeth, and D. Varga). In Proc. ACL 2005 Software Workshop 77-85 [2] Leveraging the open source ispell codebase for minority language analysis (Jointly with P. Halacsy, L. Nemeth, A. Rung, I. Szakadat, and V. Tron). In J. Carson-Berndsen (ed): Proc. SALTMIL 2004 56-59 [3] Explicit Finitism, International Journal of Theoretical Physics 2003/2 301-307 [4] Mathematical Linguistics (Jointly with G.K. Pullum) In W. Frawley (ed): Oxford International Encyclopedia of Linguistics, Oxford University Press 2003, v3 17-20 [5] Optical Character Recognition, In W. Frawley (ed): Oxford International Encyclopedia of Linguistics, Oxford University Press 2003, v3 33-34 [6] How many words are there? Glottometrics 2002/4 61-86 [7] Zipf's law outside the middle range Proc. Sixth Meeting on Mathematics of Language University of Central Florida, 1999 347-356 [8] A Robust, Language-Independent OCR System. (Jointly with Z. Lu, I. Bazzi, J. Makhoul, P. Natarajan, and R. Schwartz) In: Robert J. Mericsko (ed): Proc. 27th AIPR Workshop: Advances in Computer-Assisted Recognition SPIE Proceedings 3584 1999 [9] Quantitative Comparison of Languages. Grammars 1998/2 155-165 [10] The generative power of feature geometry. Annals of Mathematics and Artificial Intelligence 8 1993 37-46 [11] The X-bar Theory of Phrase Structure. (Jointly with G.K. Pullum) Language 66 1990 24-50 [12] == References == == External links == Kornai's home page Kornai's departmental page
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"page_id": 6558358,
"source": null,
"title": "András Kornai"
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Nitrospinota is a bacterial phylum. Despite only few described species, members of this phylum are major nitrite-oxidizing bacteria in surface waters in oceans. By oxidation of nitrite to nitrate they are important in the process of nitrification in marine environments. Although the genus Nitrospina is an aerobic bacterium, it was shown to oxidize nitrite also in oxygen minimum zone of the ocean. Depletion of oxygen in such zones leads to preference of anaerobic processes such as denitrification and nitrogen loss through anammox. Nitrospina thus outweigh nitrogen loss by nitrification also in these oxygen depleted zones. Among the cultivated isolates within the genus Nitrospina are Nitrospina gracilis and Nitrospina watsonii. Further genomes were resolved by culture-independent metagenome binning. The two Nitrospina species are, however, distantly related to environmentally abundant uncultured Nitrospinota. The two other strains were cultivated in 2020 each in the binary culture with alphaproteobacterial heterotroph. They are called "Candidatus Nitrohelix vancouverensis" and "Candidatus Nitronauta litoralis". "Nitrohelix vancouverensis" is closely related to uncultivated environmentally abundant Nitrospinota clades 1 and 2. == Taxonomy == The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) Class Nitrospinia Lucker et al. 2022 Order Nitrospinales Lücker et al. 2022 Family Nitrospinaceae Garrity, Bell & Lilburn 2006 Genus "Candidatus Nitrohelix" Mueller et al. 2021 "Ca. N. vancouverensis" Mueller et al. 2021 Genus "Candidatus Nitromaritima" Ngugi et al. 2016 Genus "Candidatus Nitronauta" Mueller et al. 2021 "Ca. N. litoralis" Mueller et al. 2021 Genus Nitrospina Watson & Waterbury 1971 N. gracilis Watson & Waterbury 1971 "N. watsonii" Spieck et al. 2014 == See also == List of bacterial orders List of bacteria genera == References ==
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"page_id": 66458263,
"source": null,
"title": "Nitrospinota"
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Chrysanthemum bonsai (Japanese: 菊の盆栽, romanized: Kiku no bonsai, lit. 'Chrysanthemum tray planting', ) is a Japanese art form using cultivation techniques to produce, in containers, chrysanthemum flowers that mimic the shape and scale of full size trees, called bonsai. == Cultivation and care == Bonsai cultivation and care requires techniques and tools that are specialized to support the growth and maintenance of the flowers in small containers. There are several cultivated varieties of chrysanthemum that possess the ability to be trained into many of the traditional bonsai styles associated with woody trunked trees and shrubs. But since chrysanthemum rarely grow to be old enough to have wood, deadwood bonsai techniques may also be used. Chrysanthemums are perennials, and while it is possible to keep a chrysanthemum bonsai alive for a number of years (old wood), it is more likely that the bonsai will be 'finished' after all the blooms have faded. The chrysanthemum bonsai artist must complete all design work in fewer than ten months. Most chrysanthemum bonsai artists in the northern latitudes of the United States start the training of their bonsai in April, and are finished by the middle of September. Traditionally in Japan the Chrysanthemum exhibitions showcase the different bonsai forms. This takes place in autumn around the months of October and November. == Styles == Various bonsai styles exist, such as the cascade style, the clinging to a rock style, and the forest style. == See also == List of species used in bonsai == References == == Bibliography == Tameji Nakajima, H. Carl Young. The art of the chrysanthemum: Japanese techniques for creating bonsai, cascades, giants and other potted styles. Harper & Row (1965) == External links == Media related to Chrysanthemum bonsai at Wikimedia Commons 日本の伝統文化・菊の盆栽Traditional culture of Japan "bonsai of chrysanthemum" Tiny Flowers,
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"page_id": 14291606,
"source": null,
"title": "Chrysanthemum bonsai"
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Big Hit: Chrysanthemum Bonsai | Longwood Gardens
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{
"page_id": 14291606,
"source": null,
"title": "Chrysanthemum bonsai"
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Palaeontology is one of the two scientific journals of the Palaeontological Association (the other being Papers in Palaeontology). It was established in 1957 and is published on behalf of the Association by Wiley-Blackwell. The editor-in-chief is Dr Paul Taylor (Natural History Museum, London). Palaeontology publishes articles on a range of palaeontological topics, including taphonomy, functional morphology, systematics, palaeo-environmental reconstruction and biostratigraphy. According to the Journal Citation Reports, the journal has a 2021 impact factor of 3.547, ranking it 3rd out of 54 journals in the category "Paleontology". == References == == External links == Official website
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{
"page_id": 12259996,
"source": null,
"title": "Palaeontology (journal)"
}
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A maraschino cherry ( MARR-ə-SKEE-noh, -SHEE-) is a preserved, sweetened cherry, typically made from light-colored sweet cherries such as the Royal Ann, Rainier, or Gold varieties. In their modern form, the cherries are first preserved in a brine solution usually containing sulfur dioxide and calcium chloride to bleach the fruit, then soaked in a suspension of food coloring (common red food dye is Allura Red AC), sugar syrup, and other components. == Uses == Maraschino cherries are used in many alcoholic and non-alcoholic drinks and cocktails, including the Old Fashioned, tequila sunrise, the Queen Mary and the Shirley Temple, giving them the nickname cocktail cherries. (This term is also used to refer to other varieties, including Amarena, Balaton, and Bing, when used for the same purpose, typically soaked in alcohol or sugar.) Sometimes the cherries, along with some of the maraschino syrup, are put into a glass of cola to make an old-fashioned or homemade cherry cola with a few brand name examples such as Coca-Cola's "Coca-Cola Cherry", Caruso's Maraschino Cola and Goose Island's Cherry Cola Stout. As a garnish, they can be used to decorate frozen yogurt, baked ham, cakes, pastry, parfaits, milkshakes and ice cream sodas. They are an integral part of an American ice cream sundae, giving rise to the term "cherry on top" in more general usage. They are frequently included in canned fruit cocktail. == Europe == The name maraschino originates from the marasca cherry of Dalmatian origin and the maraschino liqueur made from it, in which marasca cherries were crushed and preserved after being pickled. Whole cherries preserved in this liqueur were known as "maraschino cherries". This had been a local means of preserving the fruit in Dalmatia. In the 19th century, these became popular in the rest of Europe, but the supply in
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"page_id": 70311,
"source": null,
"title": "Maraschino cherry"
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Dalmatia was quite limited, so they became known as a delicacy for royalty and the wealthy. Because of the relative scarcity of the marasca, other cherries came to be preserved in various ways and sold as "maraschino". == United States == The cherries were first introduced in the United States in the late 19th century, where they were served in fine bars and restaurants. Because they were scarce and expensive, by the turn of the century American producers were experimenting with other processes for preserving cherries, with flavors such as almond extract and substitute fruit like Queen Anne cherries. Among these, alcohol was already becoming less common. In response, the USDA in 1912 defined "maraschino cherries" as "marasca cherries preserved in maraschino" under the authority of the Food and Drugs Act of 1906. The artificially-colored and sweetened Royal Anne variety were required to be called "Imitation Maraschino Cherries" instead. Food Inspection Decision 141 defined marasca cherries and maraschino themselves. It was signed on 17 Feb. 1912. During Prohibition in the United States as of 1920, the decreasingly popular alcoholic variety was illegal as well. Ernest H. Wiegand, a professor of horticulture at Oregon State University (OSU), developed the modern method of manufacturing maraschino cherries using a brine solution rather than alcohol. Accordingly, most modern maraschino cherries have only a historical connection with maraschino liqueur. According to Bob Cain, Cliff Samuels, and Hoya Yang, who worked with Wiegand at OSU, Prohibition had nothing to do with Wiegand's research: his intention was to develop a better brining process for cherries that would not soften them. When Wiegand began his research, there were several ways to preserve maraschino cherries without alcohol, long before Prohibition went into effect. Wiegand took a process that people had their own recipes for—"and who knows what they were
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{
"page_id": 70311,
"source": null,
"title": "Maraschino cherry"
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putting in there" (frequently not alcohol)—and turned it into a science, something replicable. When Wiegand began his research, sodium metabisulfite was being used to preserve maraschino cherries. Some accounts indicate that this preservation method was being used long before Prohibition. Some manufacturers used maraschino or imitation liqueurs to flavor the cherries, but newspaper stories from the early part of the century suggest that many manufacturers stopped using alcohol and artificial dyes before Prohibition. After Prohibition was repealed, lobbying by the non-alcoholic preserved cherry industry encouraged the Food and Drug Administration to revise federal policy toward canned cherries. It held a hearing in April 1939 to establish a new standard of identity. Since 1940, "maraschino cherries" have been defined as "cherries which have been dyed red, infused with sugar, and packed in a sugar syrup flavored with oil of bitter almonds or a similar flavor." FD&C Red Number 1 and 4, and FD&C Yellow Number 1 through 4 were removed from the approved list in 1960. The ban on Red Number 4 was lifted in 1965 to allow the coloring of maraschino cherries, which by then were considered mainly decorative and not a foodstuff. In 1975, William F. Randolph of the FDA ruled that if an "artificial bitter almond flavor or any synthetic flavor is used, the product must be labeled artificial or artificially flavored." The following year, the ban on Red No. 4 was reinstated. As of 2010, modern American maraschino cherries typically use FD&C Red 40 as a colorant. == See also == Amarena cherries Glacé fruit List of cherry dishes == References == == Further reading == McRobert, T. B. (March 1914). "The Maraschino Cherry". The International Confectioner. Vol. 23. pp. 43–44. Retrieved 25 August 2018. == External links == Media related to Maraschino cherries at Wikimedia Commons
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{
"page_id": 70311,
"source": null,
"title": "Maraschino cherry"
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Inborn errors of purine–pyrimidine metabolism are a class of inborn error of metabolism disorders specifically affecting purine metabolism and pyrimidine metabolism. An example is Lesch–Nyhan syndrome. Urine tests may be of use in identifying some of these disorders. == References == == External links ==
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{
"page_id": 17306283,
"source": null,
"title": "Inborn errors of purine–pyrimidine metabolism"
}
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Jian Ma (Chinese: 马坚) is an American computer scientist and computational biologist. He is the Ray and Stephanie Lane Professor of Computational Biology in the School of Computer Science at Carnegie Mellon University. He is a faculty member in the Ray and Stephanie Lane Computational Biology Department. His lab develops AI/ML methods to study the structure and function of the human genome and cellular organization and their implications for health and disease. During his Ph.D. and postdoc training, he developed algorithms to reconstruct the ancestral mammalian genome and evolutionary history. His research group has recently pioneered a series of new machine learning solutions for 3D genome organization, single-cell epigenomics, spatial omics, and complex molecular interactions. His lab also explores large language models to uncover gene regulatory mechanisms and the intricate connections among cellular components, with the aim of driving discovery and guiding experimentation. He received an NSF CAREER award in 2011. In 2020, he was awarded a Guggenheim Fellowship in Computer Science. He received the Allen Newell Award for Research Excellence (2025). He is an elected Fellow of the American Association for the Advancement of Science, the American Institute for Medical and Biological Engineering, and the International Society for Computational Biology. He leads an NIH 4D Nucleome Center to develop machine learning algorithms to better understand the cell nucleus. He served as the Program Chair for RECOMB 2024. He is also a member of the Scientific Advisory Broad of the Chan Zuckerberg Biohub Chicago (CZ Biohub Chicago) and the RECOMB Steering Committee. In 2024, he launched the Center for AI-Driven Biomedical Research (AI4BIO) at CMU, which will be a catalyst for innovations at the intersection of AI and biomedicine across the School of Computer Science and campus. == Selected Recent Publications == Chen V#, Yang M#, Cui W, Kim JS,
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Talwalkar A*, and Ma J*. Applying interpretable machine learning in computational biology - pitfalls, recommendations and opportunities for new developments. Nature Methods, 21(8):1454-1461, 2024. Xiong K#, Zhang R#, and Ma J. scGHOST: Identifying single-cell 3D genome subcompartments. Nature Methods, 21(5):814-822, 2024. Zhou T, Zhang R, Jia D, Doty RT, Munday AD, Gao D, Xin L, Abkowitz JL, Duan Z*, and Ma J*. GAGE-seq concurrently profiles multiscale 3D genome organization and gene expression in single cells. Nature Genetics, 56(8):1701-1711, 2024. Zhang Y, Boninsegna L, Yang M, Misteli T, Alber F, and Ma J. Computational methods for analysing multiscale 3D genome organization. Nature Reviews Genetics, 5(2):123-141, 2024. Chidester B#, Zhou T#, Alam S, and Ma J. SPICEMIX enables integrative single-cell spatial modeling of cell identity. Nature Genetics, 55(1):78-88, 2023. [Cover Article] Zhang R#, Zhou T#, and Ma J. Ultrafast and interpretable single-cell 3D genome analysis with Fast-Higashi. Cell Systems, 13(10):P798-807.E6, 2022. [Cover Article] Zhu X#, Zhang Y#, Wang Y, Tian D, Belmont AS, Swedlow JR, and Ma J. Nucleome Browser: An integrative and multimodal data navigation platform for 4D Nucleome. Nature Methods, 19(8):911-913, 2022. Zhang R, Zhou T, and Ma J. Multiscale and integrative single-cell Hi-C analysis with Higashi. Nature Biotechnology, 40:254–261, 2022. == References == == External links == Jian Ma's publications indexed by Google Scholar
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"page_id": 62460588,
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"title": "Jian Ma (computational biologist)"
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Ortho effect is an organic chemistry phenomenon where the presence of a chemical group at the at ortho position or the 1 and 2 position of a phenyl ring, relative to the carboxylic compound changes the chemical properties of the compound. This is caused by steric effects and bonding interactions along with polar effects caused by the various substituents which are in a given molecule, resulting in changes in its chemical and physical properties. The ortho effect is associated with substituted benzene compounds. There are three main ortho effects in substituted benzene compounds: Steric hindrance forces cause substitution of a chemical group in the ortho position of benzoic acids become stronger acids. Steric inhibition of protonation caused by substitution of anilines to become weaker bases, compared to substitution of isomers in the meta and para position. Electrophilic aromatic substitution of disubstituted benzene compounds causes steric effects which determines the regioselectivity of an incoming electrophile in disubstituted benzene compounds == Ortho substituted benzoic acids == When a substituent group is located ortho position to the carboxyl group in a substituted benzoic acid compound, the compound becomes more acidic surpassing the unmodified benzoic acid. Generally ortho-substituted benzoic acids are stronger acids than their meta and para isomers. === Mechanism of action === When ortho substitution occurs in benzoic acid, steric hindrance causes the carboxyl group to twist out of the plane of the benzene ring. The twisting inhibits the resonance of the carboxyl group with the phenyl ring, leading to increased acidity of the carboxyl group. This increased acidity contrasts with the reduced acidity caused by destabilizing cross-conjugation. The destabilizing cross-conjugation causes decreased acidity of benzoic acid compared to formic acid. ==== pKa values ==== The table given below shows pKa values of various monosubstituted benzoic acids. == Ortho substituted aniline ==
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When any group is present at ortho position to an amide group (NH2) in aniline then the basic character of that compound becomes weaker. For example, see the order of basicity of following substituted aniline:- p-Toluidine > m-Toluidine > Aniline > o-Toluidine Aniline > m-Nitroaniline > p-Nitroaniline > o-Nitroaniline Aniline > p-Haloaniline > m-Haloaniline > o-Haloaniline p-Aminophenol pKb=8.50 > o-Aminophenol pKb=9.28 > Aniline pKb=9.38 > m-Aminophenol pKb=9.80 The protonation of substituted aniline is inhibited by steric hindrance. When protonated, the nitrogen in the amino group changes its orbital hybridization from sp2 to sp3, becoming non-planar. This leads to steric hindrance between the ortho-substituted group and the hydrogen atom of the amino group, reducing the stability of the conjugate acid and consequently decreasing the pH of substituted aniline. == Electrophilic aromatic substitution of disubstituted benzene compounds == The ortho effect also occurs when a meta-directing group is positioned in a meta arrangement relative to an ortho–para-directing group, a new substituent introduced into the molecule tends to preferentially occupy the ortho position relative to the meta-directing group rather than the para position. Currently, there is no definitive explanation for the ortho effect, but it is hypothesized that there may be intramolecular assistance from the meta-directing group influencing the positioning of the incoming substituent. For example, the electrophilic aromatic nitration of 1-methyl-3-nitrobenzene affords 4-methyl-1,2-dinitrobenzene and 1-methyl-2,3-dinitrobenzene in 60.1% and 28.4% yields, respectively. In contrast, 2-methyl-1,4-dinitrobenzene (2c) is isolated in only 9.9% yield. As witnessed in the above example, when a π-acceptor substituent (πAS) is meta to a π-donor substituent (πDS), the electrophilic aromatic nitration occurs ortho to the πAS rather than para. Similar results were also observed on the nitration of 3-methylbenzoic acid in which 5-methyl-2-nitrobenzoic acid and 3-methyl-2-nitrobenzoic acid were obtained as the major compounds, whereas 3-methyl-4-nitrobenzoic acid was reported as a
|
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"page_id": 60166827,
"source": null,
"title": "Ortho effect"
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minor compound. Also in nitration of the nitration of 3-bromobenzoic acid 5-bromo-2-nitrobenzoic acid (83%yield) was obtained as major product and 3-bromo-2-nitrobenzoic acid (13% yield) as minor. On an interesting note the potential isomer 3-bromo-4-nitrobenzoic acid was not detected. == Diels-Alder reactions == The ortho effect occurs in Diels-Alder reactions when the Z-substituted dienophiles react with 1-substituted butadienes to give 3,4-disubstituted cyclohexenes, independent of the nature of diene substituents. == References == == External links == Supplemental Topics § The Ortho Effect – Department of Chemistry, Michigan State University
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The law of reciprocal proportions, also called law of equivalent proportions or law of permanent ratios, is one of the basic laws of stoichiometry. It relates the proportions in which elements combine across a number of different elements. It was first formulated by Jeremias Richter in 1791. A simple statement of the law is: If element A combines with element B and also with C, then, if B and C combine together, the proportion by weight in which they do so will be simply related to the weights of B and C which separately combine with a constant weight of A. As an example, 1 gram of sodium (Na = A) is observed to combine with either 1.54 grams of chlorine (Cl = B) or 5.52 grams of iodine (I = C). (These ratios correspond to the modern formulas NaCl and NaI). The ratio of these two weights is 5.52/1.54 = 3.58. It is also observed that 1 gram of chlorine reacts with 1.19 g of iodine. This ratio of 1.19 obeys the law because it is a simple fraction (1/3) of 3.58. (This is because it corresponds to the formula ICl3, which is one known compound of iodine and chlorine.) Similarly, hydrogen, carbon, and oxygen follow the law of reciprocal proportions. The acceptance of the law allowed tables of element equivalent weights to be drawn up. These equivalent weights were widely used by chemists in the 19th century. The other laws of stoichiometry are the law of definite proportions and the law of multiple proportions. The law of definite proportions refers to the fixed composition of any compound formed between element A and element B. The law of multiple proportions describes the stoichiometric relationship between two or more different compounds formed between element A and element B. The law
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"title": "Law of reciprocal proportions"
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states that if two different elements combine separately with a fixed mass of a third element, the ratio of the masses in which they combine are either the same or are in simple multiple ratio of the masses in which they combine with each other . == History == The law of reciprocal proportions was proposed in essence by Richter, following his determination of neutralisation ratios of metals with acids. In the early 19th century it was investigated by Berzelius, who formulated it as follows: When two substances, A and B have an affinity for two others, C and D, the ratio of the quantities C and D which saturate the same amount of A is the same as that between the quantities C and D which saturate the same amount of B. Later Jean Stas showed that within experimental error the stoichiometric laws were correct. == References ==
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{
"page_id": 42472109,
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"title": "Law of reciprocal proportions"
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The molecular formula C38H42N2O6 (molar mass : 622.74 g/mol) may refer to : Cycleanine, a selective vascular calcium antagonist Rodiasine, an alkaloid Tetrandrine, a calcium channel blocker
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"page_id": 27459313,
"source": null,
"title": "C38H42N2O6"
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In medicinal chemistry, bioisosteres are chemical substituents or groups with similar physical or chemical properties which produce broadly similar biological properties in the same chemical compound. In drug design, the purpose of exchanging one bioisostere for another is to enhance the desired biological or physical properties of a compound without making significant changes in chemical structure. The main use of this term and its techniques are related to pharmaceutical sciences. Bioisosterism is used to reduce toxicity, change bioavailability, or modify the activity of the lead compound, and may alter the metabolism of the lead. == Examples == === Classical bioisosteres === Classical bioisosterism was originally formulated by James Moir and refined by Irving Langmuir as a response to the observation that different atoms with the same valence electron structure had similar biological properties. For example, the replacement of a hydrogen atom with a fluorine atom at a site of metabolic oxidation in a drug candidate may prevent such metabolism from taking place. Because the fluorine atom is similar in size to the hydrogen atom the overall topology of the molecule is not significantly affected, leaving the desired biological activity unaffected. However, with a blocked pathway for metabolism, the drug candidate may have a longer half-life. Procainamide, an amide, has a longer duration of action than Procaine, an ester, because of the isosteric replacement of the ester oxygen with a nitrogen atom. Procainamide is a classical bioisostere because the valence electron structure of a disubstituted oxygen atom is the same as a trisubstituted nitrogen atom, as Langmuir showed. Another example is seen in a series of anti-bacterial chalcones. By modifying certain substituents, the pharmacological activity of the chalcone and its toxicity are also modified. === Non-classical bioisosteres === Non-classical bioisosteres may differ in a multitude of ways from classical bioisosteres, but
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"title": "Bioisostere"
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retain the focus on providing similar sterics and electronic profile to the original functional group. Whereas classical bioisosteres commonly conserve much of the same structural properties, nonclassical bioisosteres are much more dependent on the specific binding needs of the ligand in question and may substitute a linear functional group for a cyclic moiety, an alkyl group for a complex heteroatom moiety, or other changes that go far beyond a simple atom-for-atom switch. For example, a chloride -Cl group may often be replaced by a trifluoromethyl -CF3 group or by a cyano -C≡N group. Depending on the particular molecule used, the substitution may result in little change in activity, or either increased or decreased affinity or efficacy - depending on what factors are important for ligand binding to the target protein. Another example is aromatic rings, where a phenyl -C6H5 ring can often be replaced by a different aromatic ring such as thiophene or naphthalene which may improve efficacy, change specificity of binding or reduce metabolically labile sites on the molecule, resulting in better pharmacokinetic properties. Alloxanthine is an inhibitor of xanthine oxidase. It is also an isostere of xanthine, the normal substrate for the enzyme. Alloxanthine is considered a non-classical bioisostere because of the scaffold change. Silafluofen is an organosilicon analogue of pyrethroid insecticide Etofenprox, wherein a carbon center has been replaced by isosteric silicon, and in addition, one hydrogen atom is replaced by isosteric fluorine atom. == Other applications == Bioisosteres of some patented compounds can be discovered automatically and used to circumvent Markush structure patent claims. It has been proposed that key force field features, that is the pharmacophore, be patented instead. == See also == Grimm's hydride displacement law, an early hypothesis to describe bioisosterism == References ==
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"page_id": 5378736,
"source": null,
"title": "Bioisostere"
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Quantum 1/f noise is an intrinsic and fundamental part of quantum mechanics. Fighter pilots, photographers, and scientists all appreciate the higher quality of images and signals resulting from the consideration of quantum 1/f noise. Engineers have battled unwanted 1/f noise since 1925, giving it poetic names (such as flicker noise, funkelrauschen, bruit de scintillation, etc.) due to its mysterious nature. The Quantum 1/f noise theory was developed about 50 years later, describing the nature of 1/f noise, allowing it to be explained and calculated via straightforward engineering formulas. It allows for the low-noise optimization of materials, devices and systems of most high-technology applications of modern industry and science. The theory includes the conventional and coherent quantum 1/f effects (Q1/fE). Both effects are combined in a general engineering formula, and present in Q1/f noise, which is itself most of fundamental 1/f noise. The latter is defined as the result of the simultaneous presence of nonlinearity and a certain type of homogeneity in a system, and can be quantum or classical. The conventional Q1/fE represents 1/f fluctuations caused by bremsstrahlung, decoherence and interference in the scattering of charged particles off one another, in tunneling or in any other process in solid state physics and in general. == Other noise data sets == It has also recently been claimed that 1/f noise has been seen in higher ordered self constructing functions, as well as complex systems, both biological, chemical, and physical. == The theory == The basic derivation of quantum 1/f was made by Peter Handel, a theoretical physicist at the University of Missouri–St. Louis, and published in Physical Review A, in August 1980. Several hundred papers have been published by many authors on Handel's quantum theory on 1/f noise, which is a new aspect of quantum mechanics. They verified, applied, and further
|
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"title": "Quantum 1/f noise"
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developed the quantum 1/f noise formulas. Aldert van der Ziel, the nestor of the electronic noise field, verified and applied it in many devices and systems, together with dozens of his PhD students. It is described in the last of his 12 books: "Noise in electronic devices and circuits" published by Wiley in 1986. He also updated and generalized many verifications, practical applications, etc., in his authoritative 1988 review "Unified Description of 1/f Noise" in Proceedings of IEEE. == Denials of the theory == In 1986 and 1987, two independent groups of theorists of the field, Group-1: Theo Nieuwenhuizen, Daan Frenkel and Nico G. van Kampen; Group-2: Laszlo B. Kish and Peter Heszler; concluded that Handel's theory explaining the quantum 1/f effect was incorrect for both physical and mathematical reasons. Shortly thereafter an independent set of arguments showing that the "quantum 1/f noise" explanation of electronic 1/f noise was certainly incorrect was included in a standard review article on 1/f noise by Michael Weissman. Nieuwenhuizen, et al., state in the conclusion of their paper, "As the theoretical basis for Handel's quantum theory of 1/f noise appears to be lacking, we must conclude that the agreement with experiments is fortuituous" and, in this way, they are indicating that some of the published experimental results are suspicious. Though there have been attempts to answer some of the objections to Handel's theory, quantum 1/f noise is considered to be a non-existent effect by the majority of scientists that are familiar with its theory. The difficulty is that here a judgment based on fundamental science requires the knowledge of quantum electrodynamics however most of noise scientists are solid state physicists or engineers. Science citation index shows over 20 thousand papers annually with "noise" and/or "fluctuation"(s) keywords. The opinion of the above-mentioned relevant experts in
|
{
"page_id": 1708719,
"source": null,
"title": "Quantum 1/f noise"
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the field of noise is that, until the publication rate on the non-existent quantum 1/f noise effect stays around 1 paper/year, it is more economical to refer to the old denials than to write up new refusals. == See also == Shot noise 1/f noise White noise Johnson–Nyquist noise Signal-to-noise ratio Noise power Noise-equivalent power Phase noise List of noise topics Audio system measurements Colors of noise == References == == Further reading == For more on Quantum 1/f noise, see: Handel, Peter H. (1975-06-16). "1/f Noise-An "Infrared" Phenomenon". Physical Review Letters. 34 (24). American Physical Society (APS): 1492–1495. Bibcode:1975PhRvL..34.1492H. doi:10.1103/physrevlett.34.1492. ISSN 0031-9007. Handel, Peter H. (1975-06-16). "Nature of 1/f Phase Noise". Physical Review Letters. 34 (24). American Physical Society (APS): 1495–1498. Bibcode:1975PhRvL..34.1495H. doi:10.1103/physrevlett.34.1495. ISSN 0031-9007. Handel, Peter H. (1975). "1/f Macroscopic Quantum Fluctuations of Electric Currents Due to Bremsstrahlung with Infrared Radiative Corrections" (PDF). Zeitschrift für Naturforschung. 30a (9): 1201. Bibcode:1975ZNatA..30.1201H. doi:10.1515/zna-1975-0915. S2CID 123012715. For the coherent quantum 1/f effect, see: Handel, Peter H. (1996-03-01). "Coherent and conventional quantum 1/f effect". Physica Status Solidi B. 194 (1). Wiley: 393–409. Bibcode:1996PSSBR.194..393H. doi:10.1002/pssb.2221940133. ISSN 0370-1972. P. H. Handel: "Derivation of the Quantum 1/f Effect in Devices", IEEE Trans. on Electr. Devices (1994), submitted for publication. Handel, P.H.; Tournier, A.; Henning, B. (2005). "Quantum 1/f effect in resonant biochemical piezoelectric and MEMS sensors". IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. 52 (9). Institute of Electrical and Electronics Engineers (IEEE): 1461–1467. doi:10.1109/tuffc.2005.1516017. ISSN 0885-3010. PMID 16285443. S2CID 42681846.
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The Rubottom oxidation is a useful, high-yielding chemical reaction between silyl enol ethers and peroxyacids to give the corresponding α-hydroxy carbonyl product. The mechanism of the reaction was proposed in its original disclosure by A.G. Brook with further evidence later supplied by George M. Rubottom. After a Prilezhaev-type oxidation of the silyl enol ether with the peroxyacid to form the siloxy oxirane intermediate, acid-catalyzed ring-opening yields an oxocarbenium ion. This intermediate then participates in a 1,4-silyl migration (Brook rearrangement) to give an α-siloxy carbonyl derivative that can be readily converted to the α-hydroxy carbonyl compound in the presence of acid, base, or a fluoride source. == Reaction mechanism == == History == In 1974, three independent groups reported on the reaction now known as the Rubottom oxidation: A.G Brook, A. Hassner, and G.M. Rubottom. Considerable precedent for the reaction already existed. For instance, it was known as early as the 1930s that highly enolizable β-dicarbonyl compounds would react with peroxyacids, although it was not until the 1950s and 60s α-hydroxy β-dicarbonyl compounds were in fact the product. Considerable work by A.G Brook, during the 1950s on the mechanisms of organosilicon migrations, which are now known as Brook Rearrangements. In 1974, C.H. Heathcock described the ozonolysis of silyl enol ethers to give a carboxylic acid product via oxidative cleavage where silyl migrations were observed as side reactions and exclusively in the case of a bicyclic system. == General features == The original implementations of the Rubottom oxidation featured the peroxyacid meta-chloroperoxybenzoic acid (mCPBA) as the oxidant in dichloromethane (DCM), in the case of Hassner and Brook, and hexanes for Rubottom. While the reaction has been tweaked and modified since 1974, mCPBA is still commonly used as the oxidant with slightly more variation in the solvent choice. DCM remains the most common
|
{
"page_id": 7344825,
"source": null,
"title": "Rubottom oxidation"
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solvent followed by various hydrocarbon solvents including pentane and toluene. Notably, the reaction proceeds at relatively low temperatures and heating beyond room temperature is not necessary. Low temperatures allow the standard Rubottom oxidation conditions to be amenable with a variety of sensitive functionalities making it ideal for complex molecule synthesis (See synthetic examples below). Silyl enol ether substrates can be prepared regioselectively from ketones or aldehydes by employing thermodynamic or kinetic control to the enolization prior to trapping with the desired organosilicon source (usually a chloride or triflate e.g. TBSCl or TBSOTf). As illustrated by the synthetic examples below, silyl enol ethers can be isolated prior to exposure to the reaction conditions, or the crude material can be immediately subjected to oxidation without isolation. Both acyclic and cyclic silyl enol ether derivatives can be prepared in this way and subsequently be used as substrates in the Rubottom oxidation. Below are some representative Rubottom oxidation products synthesized in the seminal papers. In 1978, Rubottom showed that siloxy 1,3 dienes, derived from acyclic or cyclic enones could also serve as substrates for the Rubottom oxidation to forge α-hydroxy enones after treatment with triethyl ammonium fluoride. These substrates give a single regioisomer under the reaction conditions due to the electron-rich nature of the silyl enol pi-bond (See synthesis of Periplanone B below). == Modifications and improvements == The Rubottom oxidation has remained largely unchanged since its initial disclosure, but one of the major drawbacks of standard conditions is the acidic environment, which can lead to unwanted side reactions and degradation. A simple sodium bicarbonate buffer system is commonly employed to alleviate this issue, which is especially problematic in bicyclic and other complex molecule syntheses (see synthetic examples). The introduction of chiral oxidants has also allowed for the synthesis of enantiopure α-hydroxy carbonyl derivatives
|
{
"page_id": 7344825,
"source": null,
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from their corresponding silyl enol ethers. The first example of an enantioselective Rubottom oxidation was published by F.A. Davis in 1987 and showcased the Davis chiral oxaziridine methodology (Davis oxidation) to give good yields but modest enantiomeric excesses. In 1992, K.B. Sharpless showed that the asymmetric dihydroxylation conditions developed in his group could be harnessed to give either (R)- or (S)- α-hydroxy ketones from the corresponding silyl enol ethers depending on which Chinchona alkaloid-derived chiral ligands were employed. The groups of Y. Shi and W. Adam published another enantioselective variant of the Rubottom oxidation in 1998 using the Shi chiral ketone in the presence of oxone in a buffered system to furnish α-hydroxy ketones in high yield and high enantiomeric excess. The Adam group also published another paper in 1998 utilizing manganese(III)-(Salen)complexes in the presence of NaOCl (bleach) as the oxidant and 4-phenylpyridine N-oxide as an additive in a phosphate buffered system. This methodology also gave high yields and enentioselectivities for silyl enol ethers as well as silyl ketene acetals derived from esters. Along with chiral oxidants, variants of mCPBA have been examined. Stankovic and Espenson published a variation of the Rubottom oxidation where methyltrioxorhenium is used as a catalytic oxidant in the presence of stoichiometric hydrogen peroxide. This methodology gives acyclic and cyclic α-hydroxy ketones in high yield with a cheap, commercially available oxidant. An inherent problem with mCPBA is its inability to oxidize silyl ketene acetals. In order to synthesize α-hydroxy esters, different oxidants are needed such as NaOCl (see above), lead(IV) acetate, or a hypofluorous acid-acetonitrile (HOF-ACN) complex. The Rubottom group found that lead(IV) acetate in DCM or benzene gave good yields of acyclic and cyclic α-hydroxy esters after treatment of the crude reaction mixture with triethylammonium fluoride. Later, the highly electrophilic HOF-ACN complex was used by
|
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S. Rozen to oxidize a variety of electron rich silyl enol ethers, silyl ketene acetals, and bis(silyl acetals), derived from carboxylic acids, in good yields at or below room temperature. == Applications in synthesis == The following examples represent only a small portion of syntheses that highlight the use of the Rubottom oxidation to install an important α-hydroxy functionality. Some of the major features of the following syntheses include the use of buffered conditions to protect sensitive substrates and the diastereoselective installation of the α-hydroxy group due to substrate controlled facial bias. For more examples see refs The Rubottom oxidation was used in the synthesis of periplanone B, a sex pheromone excreted by the female American cockroach. The synthesis employed an anionic oxy-Cope rearrangement coupled to a Rubottom oxidation. After heating in the presence of potassium hydride (KH) and 18-crown-6 (18-C-6) to effect the anionic oxy-Cope, the enolate intermediate was trapped with trimethylsilyl chloride (TMSCl). The silyl enol ether intermediate could then be treated with mCPBA under Rubottom oxidation conditions to give the desired α-hydroxy carbonyl compound that could then be carried on to (±)-periplanone B and its diastereomers to prove its structure. Brevisamide, a proposed biosynthetic precursor for a polyether marine toxin, was synthesized by Ghosh and Li, one step of which is a Rubottom oxidation of the cyclic silyl enol ether under buffered conditions. Chiral chromium catalyst B was developed the Jacobsen group and confers high levels of enantio- and diastereoselectivity. The stereocenters conveniently set in the Diels-Alder reaction direct the oxidation to the less hindered face, giving a single diastereomer, which could then be carried on in 14 more steps to Brevisamide. Wang and coworkers developed a robust, kilogram-scale synthesis of the potent derivative 2S-hydroxymutilin from pleuromutilin, an antibiotic produced by various species of basidiomycetes. Basic hydrolysis
|
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to remove the hydroxyl ester moiety of pleuromutilin yielded mutilin. Subsequent treatment with lithium hexamethyldisilazide (LiHMDS) and TMSCl gave the TMS-protected silyl enol ether, which was immediately subjected to an acetic acid- (HOAc) pyridine- (Py) buffered Rubottom oxidation before acidic hydrolysis to afford 2S-hydroxymutilin. This highly optimized sequence features two important aspects. First, the authors originally generated the silyl enol ether using triethylamine, which gave a mixture of the desired kinetic product, (shown below) the undesired thermodynamic product, and hydrolysis back to mutilin. The authors blamed the formation of the acidic triethylammonium (pKa = 10.6) byproduct for the undesired side products and remedied this by using the LiHMDS to exclusively form the desired kinetic product with no acid-catalyzed side reactions due to the significantly lower acidity of the protonated product (pKa = 26). Second, while oxidation occurred from the desired convex face of the silyl enol ether, the authors saw a significant number of overoxidation products that they attributed to the stability of the oxocarbenium ion intermediate under sodium bicarbonate buffered conditions. They hypothesized that the increased lifetime of the intermediate species would allow for over oxidation to occur. After a significant amount of optimization, it was found that an HOAc/Py buffer trapped the oxocarbenium intermediate and prevented overoxidation to exclusively give 2S-hydroxymutilin after hydrolysis of the silyl protecting groups. Ovalicin, fumagillin, and their derivatives exhibit strong anti-angiogenesis properties and have seen numerous total syntheses since their isolation. Corey and Dittami reported the first total synthesis of racemic ovalicin in 1985 followed by two asymmetric syntheses reported in 1994 by Samadi and Corey which featured a chiral pool strategy from L-quebrachitol and an asymmetric dihydroxylation, respectively. In 2010, Yadav and coworkers reported a route that intercepted the Samadi route from the chiral pool starting material D-ribose. A standard Rubottom oxidation
|
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"page_id": 7344825,
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gives a single stereoisomer due to substrate control and represents the key stereogenic step in the route to the Samadi ketone. Once synthesized, the Samadi ketone could be elaborated to (−)-ovalicin through known steps. Velutinol A was first synthesized by Isaka and coworkers. The authors show that the high regioselectivity of this reaction is directed by the hydroxyl group syn to the ring-fusion proton. Reactions where the stereochemistry of the hydroxyl group is inverted saw lower regioselectivity, and removal of the hydroxyl group gave the exclusive formation of the other regioisomer. It is likely that the close proximity of the hydroxyl group in the syn isomer acidifies the ring-fusion proton through hydrogen-bonding interactions, thus facilitating regioselective deprotonation by triethylamine. The silyl enol ether was then treated with excess mCPBA to facilitate a “double” Rubottom oxidation to give the exo product with both hydroxyl groups on the outside of the fused ring system. This dihydroxy product was then transformed into Velutinol A in three additional steps. The Clive group utilized the Rubottom oxidation in the synthesis of an advanced intermediate for their degradation studies of the cholesterol-lowering fungal metabolite mevinolin. This interesting sequence features the addition of excess n-butyllithium (BuLi) in the presence of lithium diisopropylamide (LDA) for full conversion of the bicyclic ketone derivative to the corresponding silyl enol ether. Without BuLi the authors report a maximum yield of only 72%. Subsequent buffered Rubottom oxidation conditions with sodium bicarbonate in ethyl acetate afforded the α-hydroxy ketone as a single diastereomer. The Falk group synthesized various derivatives of phosphatidyl-D-myo-inositol to aid in the study of the various phosphatidylinositol 3-kinase (PI3K) cell signaling pathways. Their route to the collection of substrate analogs exploits a substrate-controlled stereoselective Rubottom oxidation using dimethyl dioxirane(DMDO) as the oxidant and catalytic camphorsulfonic acid (CSA) to aid in
|
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hydrolysis. For protecting groups see ref == Problems and shortcomings == While the Rubottom oxidation generally gives good yields and is highly scalable (see 2S-hydroxymutilin synthesis), there are still some problems with the reaction. As mentioned above, the acidic reaction conditions are not tolerated by many complex substrates, but this can be abrogated with the use of buffer systems. Poor atom economy is also a major issue with the reaction because it requires stoichiometric oxidant, which generates large amounts of waste. Peroxides can also be dangerous to work with. mCPBA is known to detonate from shock or sparks. == α-Hydroxylation of related compounds == Although silyl enol ethers of aldehydes and ketones are the traditional substrates for the Rubottom oxidation, as mentioned above, silyl ketene acetals and bis (silyl acetals) can be oxidized to their α-hydroxy ester or carboxylic acid derivatives using lead(IV) acetate or hypofluorous acid-acetonitrile (HOF–ACN). However, these α-hydroxylations do not proceed via silyl enol ether intermediates and are therefore not technically Rubottom oxidations. Various oxidants can be used to oxidize many of these carbonyl derivatives after they are converted to their respective enolate or related anion. Some common oxidants are peroxy acids, molecular oxygen, and hypervalent iodine reagents. == References == == Bibliography == Kürti, L.; Czakó, B. (2005) Strategic Applications of Named Reactions in Organic Synthesis, Elsevier, ISBN 0124297854. Li, J.J. (2009) Name Reactions: A Collection of Detailed Mechanisms and Synthetic Applications, 4th Edition, Springer, ISBN 8132204298 == External links == Organic Chemistry Portal Myers' Handouts
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This timeline lists notable events in the history of research into senescence or biological aging, including the research and development of life extension methods, brain aging delay methods and rejuvenation. People have long been interested in making their lives longer and healthier. The most anсient Egyptian, Indian and Chinese books contain reasoning about aging. Ancient Egyptians used garlic in large quantities to extend their lifespan. Hippocrates (c. 460 – c. 370 BCE), in his Aphorisms, and Aristotle (384–322 BCE), in On youth and old age, expressed their opinions about reasons for old age and gave advice about lifestyle. Medieval Persian physician Ibn Sina (c. 980 – 1037), known in the West as Avicenna, summarized the achievements of earlier generations about this issue. == Background == Descriptions of rejuvenation and immortality remedies are often found in the writings of alchemists. But all those remedies did not allow even alchemists themselves to live longer than a hundred years. Though the average lifespan of people through the past millennia increased significantly, maximum lifespan almost did not change - even in ancient times there were fairly well and unbiasedly documented cases when some people lived for more than a hundred years (for example, Terentia who lived 103 or 104 years). While among the billions of people of the modern world, there is only one case of life over 120 years (Jeanne Calment, 122 years). The super-long lives of people that are mentioned in ancient books, apparently, are highly exaggerated, since archaeological data show that even the oldest of the ancient people lived no more than modern supercentenarians. In some cases the exaggeration, possibly, is not intentional but occurs due to errors in translation between languages and synchronization of chronological systems. The species limit of human life is estimated by scientists at 125–127 years, and
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even in the most ideal conditions a person will not live longer due to aging of the body. Some scientists believe that, even if medicine learns how to treat all major diseases, that will increase the average lifespan of people in developed countries by only about 10 years. For example, biogerontologist Leonard Hayflick stated that the natural average lifespan for humans is 92 years. Meanwhile, the life expectancy for Japanese already now is more than 84 years, and for Monaco it is reported to be more than 89 years. It may not be possible to achieve further increases without development of new biomedical technologies and approaches. Searches of various equivalents of the elixir of youth happened yet in ancient times: people hoped to find a miraculous remedy in faraway territories, tried to use magic and alchemy. Scientific and technological attempts began at the end of the 19th century. For their intended purpose, all of them turned out to be inefficient at best, sometimes led to premature death, but they had many useful and sometimes unexpected consequences. == Timeline == === Ancient === 350 BCE — The Greek philosopher Aristotle, arguably the first philosopher to make a serious attempt to scientifically explain aging, proposes his thesis on aging. He suggests that aging is a process by which human and animal bodies, which are naturally hot and wet, gradually become dry and cold, and theorizes that more moisture delays aging. 259–210 BCE — years of life of the Chinese emperor Qin Shi Huang, who united China under his rule. All his life he persistently searched for an elixir of youth and died trying, presumably taking "pills of immortality", containing mercury. 156–87 BCE — years of life of the Chinese emperor Wu of Han, who persistently tried to find a way to achieve
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immortality, mainly by means of magic. He used services of various magicians. But Wu of Han was not a naive person – he thoroughly rechecked their abilities and if he identified the person as a quack, he executed him. 63 BC–14 CE — years of life of Caesar Augustus, the first Roman emperor, who is considered one of the most effective leaders of the Ancient Rome. For him an eternal youth was an obsession. In particular, contrary to the Roman tradition to create statues as realistic as possible, he always ordered to portray himself young. There are many of his "youthful" statues but researchers still do not know how he looked in old age. 3rd–17th century — the period of alchemy. There are several directions in alchemy, and it was distributed over a huge territory. But almost everywhere, in one form or another, there was the concept of a "philosopher's stone" – some substance that is able to turn other metals into gold, and when taken internally in small doses, heal all diseases, rejuvenate an old body and even give biological immortality. Alternatively, there were attempts to prepare "pills of immortality". During centuries alchemy gradually transformed to chemistry, in parallel giving birth to many adjacent sciences or enriching them. It is worth noticing the direction of iatrochemistry – a rational direction of alchemy with the main goal of preparing medicinal products. The pioneers of iatrochemistry were Paracelsus (1493–1541), Jan Baptist van Helmont (1580–1644) and Franciscus Sylvius (1614–1672). The converging field of alchemy was transformed into pharmacy. 1513 — searching for the Fountain of Youth is in popular culture thought to be one of the purposes of the expedition of the Spanish conquistador Juan Ponce de León, which lead to the discovery of Florida – however, there is no contemporary evidence
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of this, and this purpose is considered a myth by historians. 1550 — a Venetian nobleman Luigi Cornaro published the book The Art of Living Long, describing the style of life for the achievement of longevity. The book was translated into many languages. The English version of the book till the 19th century went through more than 50 editions. The main idea of the book: in order to live many years, you need to live in moderation, eat simply and little. In his youth Cornaro led a free and immoderate life, as a result by the age of 35 he had many health problems. But by changing his lifestyle he was able to live to 98 (1467–1566). (Though it is possible that he exaggerated his age by about 17 years to give his recommendations more weight.) === 19th century to WWII === From the end of the 19th century, systematic scientific and technical studies began on the processes of slowing down aging and possible rejuvenation. The period of world history between the two world wars is a very complicated, difficult and ambiguous time of world history. In many spheres of life, there were ideas that were radical-bold, but not always intelligent, ethical and moral from the point of view of modern knowledge, foundations and norms. This also affected the aging research, the spirit of which corresponded to the spirit of that time: attempting bold experiments, often on people, intensively implementing in practice treatments that we may now consider ridiculous. Those attempts had both bad and good consequences. But those researches were already scientific. As it often happens in science, it is often difficult to establish priority considering, who was the first person beginning to use one or another approach. Usually the first experiments are done by enthusiasts and have doubtful
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positive effects. Some researchers work in parallel. Then at some moment the persons emerge who developed the approaches and made them public. 1825 The first publication of the Gompertz–Makeham law of mortality that in the simplest form is: p = a + bx. According to the law, the probability of death p is defined as the sum of age-independent component a and the component depending on age bx which with age increases exponentially. If we place organisms in an absolutely protected environment and in this way make the first component negligible, the probability of death will be completely defined by the second component which actually describes the probability to die from aging. 1860s Alfred Russel Wallace writes down what is probably the first evolutionary theory of aging. In notes written sometime between 1865 and 1870, he proposed a wear and tear theory of aging, suggesting that older animals which continue to consume resources, competing with their offspring in an environment with limited food, were disfavored by natural selection. Therefore, he suggested that aging was an evolved trait which allowed an organism's descendants to thrive. 1882 August Weismann puts forward the wear and tear theory of aging independently of Wallace. 1889 Rejuvenation experiment conducted on himself by the French doctor Charles-Édouard Brown-Séquard. He made himself a few subcutaneous injections from the testicles of young dogs and guinea pigs and claimed that the injections were accompanied by significant and long pain, but then he observed an improvement of the physical condition of the organism and increase of mental activity. Experiments of other scientists, at first, produced the same results but later it became clear that the period of reinforced activity is followed by a period of decline. At the moment of the experiment Charles-Édouard Brown-Séquard was 72 years old. After the experiment
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he claimed he felt as if he became younger by 30 years. However, 5 years later he died. But other doctors picked up this method and it created the foundation for the development of hormone replacement therapy. 1903 Ilya Mechnikov coined the term "gerontology". The term originates from the Greek γέρων, geron, "old man" and -λογία, -logia, "study of". From 1897 to 1916 Mechnikov conducted many studies on the effect of acidified dairy products (especially Bulgarian yogurt and bacteria used for its production) on longevity and quality of life in old age. He developed the concept of probiotic diet that promotes long healthy life. In 1908 Mechnikov received the Nobel Prize for his work on immunology (adjacent area of his research). Adhering to his diet, Mechnikov lived a very long life compared to his short-lived relatives. 1914 Dr. Frank Lydston from Chicago performed human testis transplants on several patients, including himself, and said that there were some rejuvenating consequences (such as returning his gray hair to its original color and improving of sexual performance). These works remained little known. The work of Leo L. Stanley, that he began to do since 1919, received much more prominence (see further). 1915–1917 Experiments to find out the effects of food restriction on the life duration of rats, conducted by Thomas Osborne. Apparently, these were the first systematic experiments in this direction. These experiments remained little known. The method was popularized by Clive McCay in 1934–1935 (see further). 1910s–1930s Austrian physiologist Eugen Steinach was trying to achieve rejuvenation effects by means of different surgical operations such as partial vasectomy for men, ligation of fallopian tubes for women, transplantation of testicles, etc. And although later these operations were found to be ineffective, they allowed the researchers to recognize the role of the sexual glands and
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sexual hormones in the formation of the first and secondary sex characteristics, enriched physiology, laid the foundation for the science of sexology, formed the basis for sex reassignment surgeries. From 1921 to 1938, Eugen Steinach was nominated for the Nobel Prize many times (according to various sources, from 6 to 11 times), but never received it. 1910s–1930s Numerous experiments for obtaining rejuvenating effects by means of transplantation of organs and tissues. Among the most notable researchers who worked in this direction, there were Alexis Carrel (who developed the technology of anastomosis of blood vessels and advanced asepsis, a Nobel laureate of 1912), Mathieu Jaboulay, Emerich Ullmann, Jacques Loeb, John Northrop, Porfiry Bakhmetiev. And although such interventions were later found to be ineffective for their intended purposes, those works led to the creation of tissue engineering, techniques for cardiopulmonary bypass and dialysis, established the foundation for the technologies for storing organs extracted from a person outside the body (which now are used, for example, during organ donation), the emergence of cryobiology. 1920s–1930s In medical practice, sex gland transplants were introduced to obtain rejuvenating effects. (Though separate experiments in this direction were done even earlier, even in antiquity.) The earlier mentioned operations of Dr. Frank Lydston in 1914 remained almost unnoticed. But the works of Leo Leonidas Stanley quickly received widespread scientific notice. Stanley was a physician at a prison in California and began to do these operations since 1919, using glands of executed criminals. In the following years, such operations were done by dozens of physicians (including Eugen Steinach) but they became most famous due to the activity of the French surgeon of Russian extraction Serge/Samuel Voronoff. It was believed that transplantation of sex glands provides more durable effects than injection of a suspension of ground glands. In case of transplantation
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from human to human, the glands of executed criminals were usually used. But due to a shortage of materials, the sex glands of young healthy monkeys were widely used, which were specially grown for this purpose (usually thin sections of the glands were implanted). In some cases soon after the operation, there were indeed noticeable positive changes in appearance and behavior (with a rapid senility of the body soon following). There were many messages about wonderful results of the operations that, apparently, were false advertising of unscrupulous doctors. But numerous failures became apparent, for which the method was sharply criticized and banned. Serge Voronoff and some other doctors, who claimed producing wonderful results after the operations, got bad reputation. However, despite the failure in the main direction, the conducted research led to the emergence of allotransplantation and xenotransplantation directions in surgery, brought significant knowledge about the effect of sex hormones on the body, stimulated their study. It may be just a coincidence but in 1929–33 several varieties of estrogen were discovered, and testosterone was isolated in 1935. Also these experiments formed the basis for several works of public culture (for example, Heart of a Dog by Mikhail Bulgakov, The Adventure of the Creeping Man from the series about Sherlock Holmes, a song Monkey-Doodle-Doo of Irving Berlin). 1926–1928 Experiments on rejuvenation by blood transfusion, conducted by Alexander Bogdanov in the world's first Institute for Blood Transfusion especially created for that purpose. Bogdanov himself died during one of the experiments, because at that time little was known about the factors of blood compatibility of different people. The institute, having undergone several renames, exists and is still actively working. The second head of the institute was Alexander Bogomolets (see further). 1930s Beginning of attempts of rejuvenation by methods of cell injections. A special
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role belongs here to the Swiss physician Paul Niehans – he was not the first but he was the one who developed this approach the most. Among his patients there were many famous people (including Winston Churchill, Charles de Gaulle, Pope Pius XII). So, in 1952, about 3000 injections of about 10 cm3 of cell suspension were reported. As a consequence, cell therapy and regenerative medicine were formed. Since the 1960s, attempts have been made to inject not only whole cells but also their constituent parts (such as isolated DNA and RNA). But usage of embryonic drugs sometimes caused serious complications, so the American association of physicians recognized the method of cell therapy as dangerous. 1930 The first world's journal about aging and longevity. It was established in Japan and has the name Acta Gerontologica Japonica (Yokufuen Chosa Kenkyu Kiyo). 1933 The first institute in the world dedicated to study of aging. It was created in Kishinev (at that time inside the Kingdom of Romania) by Dimu Kotsovsky. Initially the institute was maintained by his own means, and was subsequently recognized by the Romanian government. The name is Romanian: Institutul Pentru Studierea si Combaterea Batranetii = German: Institut für Altersforschung und Altersbekämpfung = Institute for The Study and Combat of Aging. 1934 The first widely known scientific publication on the impact of dietary restriction on life expectancy, authored by Clive McCay. McCay's group carried out intensive research in this direction in 1930–43, soon other scientists began to do related research. The effect of increasing life expectancy by starvation is usually observed in rats and mice, whose development until puberty is very labile (growth retardation and puberty, decreased metabolism and body temperature). In larger animals, such as rabbits, dogs and monkeys, the effect is less pronounced. The impact of fasting on
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human life expectancy still remains a question where not everything is clear and is unambiguous. 1936 The first European (and Western) journal about aging and longevity. It was published in Kishinev by Dimu Kotsovsky. During the first year of existence it was called Monatsberichte, then got the name German: Altersprobleme: Zeitschrift für Internationale Altersforschung und Altersbekämpfung = "Problems of Aging: Journal for the International Study and Combat of Aging". The journal published materials mostly in the German language, less in French and English. 1937 A Ukrainian Soviet pathophysiologist Alexander Bogomolets created antireticular cytotoxic serum in the hope to extend life of people to 150 years. Although the drug did not achieve its main goal, it has become widely used for the treatment of a number of diseases, especially infectious diseases and fractures. The serum of Bogomolets was actively used in Soviet hospitals during WWII. For his work, Alexander Bogomolets received in 1941 the Stalin Prize, which for Soviet scientists of those years was even more important than the Nobel Prize. 1938 The first specialized society dedicated to the study of aging. It was formed in Germany, Leipzig and was named the German Society for Aging Research (German: Deutsche Gesellschaft für Altersforschung, soon renamed to Deutsche Gesellschaft für Alternsforschung). The founder is Max Bürger. He also established the specialized journal Zeitschrift für Altersforschung – it is already the third such journal in the world after the previously mentioned Japanese and Romanian journals. 1938 The world's first scientific conference on aging and longevity in 1938 in Kiev, that was convened by Alexander Bogomolets. 1939 In the United Kingdom, the British Society for Research on Ageing is formed. The founder is Vladimir Korenchevsky who emigrated there from the former Russian Empire. === After WWII === After World War II, research tools and technologies
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of another level appeared. Thanks to these technologies, it became understandable what really occurs inside cells and between them (for example, the model of the DNA double helix was created in 1953). At the same time, changed ethical norms did not allow cardinal experiments to be performed on humans, as had been possible in previous decades. Consequently, the influence of different factors could be estimated only indirectly. 1945 In the US, the Gerontological Society of America is formed. The founder is Edmund Vincent Cowdry. 1950 Largely thanks to the collaborative efforts of Korenchevsky and Cowdry, the International Association of Gerontology is formed, later renamed to the International Association of Gerontology and Geriatrics (IAGG). The organization was registered in Belgium, and that is where its first conference took place. Slowly, gradually, the ideas began to spread that the problems of aging cannot be solved within the framework and efforts of one nation – therefore the international interaction is necessary. 1952 Peter Medawar proposed the mutation accumulation theory to explain how the aging process could have evolved. 1954 Vladimir Dilman formulated the hypothesis of aging that at first become known only in the USSR, as the elevation hypothesis. In 1968 it took the form and became known as the neuroendocrine theory of aging. 1956 Denham Harman proposed the free-radical theory of aging and demonstrated that free radical reactions contribute to the degradation of biological systems. The theory is based on the ideas of Rebeca Gerschman and her colleagues put forward in 1945. 1957 George Williams proposed the antagonistic pleiotropy hypothesis for the explanation of the emergence of aging. 1958 Physicist Gioacchino Failla proposed the hypothesis that aging is caused by the accumulation of DNA damage. The next year the hypothesis was developed by the physicist Leo Szilard, resulting in a number of
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related theories under the general name DNA damage theory of aging. 1961 Discovery by Leonard Hayflick of the limit of divisions for somatic cells, named the Hayflick limit. Hayflick found that normal human cells, extracted from fetus, are able to divide only about 50 times, after that they enter a senescence phase. 1969 Immunological theory of aging proposed by Roy Walford. 1974 Formation of the National Institute on Aging (NIA) – the aging of the population began to be perceived as a problem deserving state attention (and not as a problem of separate scientific societies). Since 1984, the NIA has begun to contribute in every way to the work of the National Archive of Computerized Data on Aging (NACDA). 1977 To explain aging, Thomas Kirkwood proposed the disposable soma theory. According to the theory, the organism has only a limited amount of resources that it has to allocate between different purposes (such as growth, reproduction, repair of damage). Aging occurs due to the limitation of resources that the body can afford to spend on repair. 1985 The discovery of telomerase, a ribonucleoprotein that is able to restore shortened telomeres. The discovery was made by Elizabeth Blackburn and Carol Greider. This research is based on the theoretical works of Alexey Olovnikov. The study of telomeres and telomerase required many more years and the work of many scientists around the world. For this work, in 2009, Elizabeth Blackburn, Carol Greider and Jack Szostak received the Nobel prize, in the same year Alexey Olovnikov was awarded the Demidov Prize. 1986 Reliability theory of aging and longevity proposed by Leonid Gavrilov and Natalia Gavrilova. At first it was published only in the USSR. In English language the theory was published five years later, in 1991. 1990 Formation of the Gerontology Research Group (GRG) which
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searches for supercentenarians around the world and verifies their age. Whenever possible, the organization tries to collect data on why these people live significantly longer than the average person. The organization regularly publishes a list of the oldest verified living supercentenarians. 1992 National Archive of Computerized Data on Aging (NACDA) published in the Internet the first 28 datasets related to aging. Gradually the number of published datasets has grown to over 1600 and continues to grow. These datasets are available to any researcher around the world at no charge, so they can search in them for new patterns. The site also provides some tools to facilitate analysis. 1993 Cynthia Kenyon and Ramon Tabtiang doubled the lifespan of C. elegans nematodes by partially disabling a gene, with the nematodes remaining relatively healthy for significantly longer. The discovery was a revolutionary breakthrough in aging research, demonstrating that the aging process could be controlled in the laboratory, and sparked more research into the molecular biology of aging. 1995 Method for detection of senescent cells using a cytochemical assay. 1997 The absolute record for the duration of human life. The French woman Jeanne Calment lived 122 years and 164 days (the record is still held). 1998 A record for the duration of life among males. The Danish-American Christian Mortensen lived 115 years and 252 days. 1998 Scientists managed to extend, in a laboratory environment, the life of normal human cells beyond the Hayflick limit using telomerase. 1999 Establishment of the Buck Institute for Research on Aging – the first institute originally established primarily to study intervention into the aging process. 1999 Sierra Sciences, a biotechnology company focused on aging research with the goal of curing human aging, was founded by William H. Andrews. === 21st century === The research activity has increased. There is
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a shift of focus of the scientific community from the passive study of aging and theorizing to research aimed at intervening in the aging process to extend the lives of organisms beyond their genetic limits. Scientific-commercial companies appear, which aim to create practical technologies for measuring the biological age of a person (in contrast to chronological age) and extend the life of people to a greater extend than the healthy lifestyle and preventive medicine can provide. In society and media there are discussions not only about whether a significant prolongation of life is physically possible, but also whether it is appropriate, about the possibility of officially classifying aging as a disease, and about the possibility of mass testing on human volunteers. 2003 First evidence that aging of nematodes is regulated via TOR signaling. 2003 The Methuselah Foundation is organized by Aubrey de Grey and David Gobel to create life extension technologies based on the Strategies for engineered negligible senescence (SENS) approaches and supporting related research in other organizations. 2003 Andrzej Bartke created a mouse that lived 1,819 days (8 days short of 5 years), while the maximum lifespan for this species is 1,030–1,070 days. By human standards, such longevity is equivalent to about 180 years. 2004 First evidence that aging of nematodes is regulated by AMP-Kinase. 2004 Aubrey de Grey coined the term "longevity escape velocity" (LEV). Though the concept per se has been present in the life extension community since at least the 1970s (for example, Robert Wilson, essay Next Stop, Immortality, 1978). 2004 As a result of the use of anti-aging therapy, a team of scientists led by Stephen Spindler managed to extend the life of a group of already adult mice to an average of 3.5 years. For this achievement, the first Methuselah Mouse Rejuvenation 'M Prize'
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was awarded. 2004 Creation of the first curated database of genes related to human ageing: GenAge. 2006 Creation of induced stem cells (iSC) from somatic cells by the simultaneous action of several factors. First produced by the Japanese scientist Shinya Yamanaka. In 2012, Shinya Yamanaka and John Gurdon received the Nobel Prize for their work on reprogramming mature cells into pluripotent cells. 2007 Extension of mouse lifespan via deletion of insulin receptor in the brain. 2007 The book Ending Aging written by Aubrey de Grey and his research assistant Michael Rae. 2007 First evidence that a pharmacological agent (namely, metformin) at a certain dosage is capable to increase the lifespan of mice. 2008 Foundation of the Max Planck Institute for Biology of Ageing. 2008 (approximately) It was observed that different variants of FOXO3 gene are associated with human longevity. Since then, research has been conducted to better understand its functions and the mechanism of action. 2009 Association of genetic variants in insulin/IGF1 signaling with human longevity. 2009 A second pharmacological agent (namely, rapamycin) was shown to be capable to increase the lifespan of mice. For this discovery Davе Sharp receive a special prize from the Methuselah Foundation. 2009 The SENS Research Foundation, a research institute dedicated to studying the aging process and ways to reverse it based on the strategies for engineered negligible senescence approach, was established by Aubrey de Grey. 2010s first half The appearance of small political parties in different countries that make the promotion of anti-aging technologies part of their political platforms (for example, Science Party of Australia, U.S. Transhumanist Party, Party for Rejuvenation Research). 2010 Harvard University scientists at the Dana–Farber Cancer Institute partially reversed age-related degeneration in mice by engineering an improved telomerase gene. 2012 It was discovered that protein Sirtuin 6 (SIRT6) regulates the
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lifespan of male mice (but not female mice). 2013 The pan-tissue Epigenetic clock is a molecular biomarker by Steve Horvath that facilitates the measurement of the age of all human tissues based on cytosine methylation. 2013 The scientific journal Cell published the article "The Hallmarks of Aging", that was translated to several languages and determined the directions of many studies. 2013 A record for the duration of life among males. Japanese Jiroemon Kimura lived 116 years and 54 days (that is 167 days longer than the previous record). 2013 It was discovered that brain-specific overexpression of Sirtuin 1 (SIRT1) is also capable to extend lifespan and delay aging in mice. 2013 Google and other investors created the company Calico to combat aging and related diseases. Investors provided Calico with more than a billion dollars of funding. Arthur Levinson became CEO of the company and one of its investors. 2014 First evidence that pharmacological activation of SIRT1 extends lifespan in mice and improves their health. 2014 Establishment of the Dog Aging Project at the University of Washington, a decade-long study of aging in dogs which includes clinical trials of rapamycin in some of them to test its effects on lifespan, with the project's ultimate goal being to translate the results into further understanding aging in humans and ways to target it. 2010s second half The emergence of official discussions about the possibility of recognizing aging as a disease. 2016 It was found that the replenishment of NAD+ in the organism of mice through precursor molecules improves the functioning of mitochondria and stem cells, and also leads to an increase in their lifespan. One of these NAD+ precursor molecules is NMN. 2016 Demonstration that a combination of longevity associated drugs can additively extend lifespan, at least in mice. 2016 As part of
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the implementation of the SENS programs, researchers managed to make two mitochondrial genes, ATP8 and ATP6, stably express from the cell nucleus in the cell culture. 2016 Scientists show that expressing Yamanaka reprogramming factors in mice with premature aging can extend their lifespan by about 20%. 2017 The discovery that a naturally occurring polymorphism in human signaling pathways is in some cases associated with health and longevity. It was also detected that, the same as in mice, this association can depend on the sex (it can be observed for one sex but not for another). This indicates that by correctly influencing these pathways, it is theoretically possible to alter lifespan and healthspan in humans. 2017 AgeX Therapeutics, a biotechnology company focused on medical therapeutics related to longevity, was founded. 2018 The Nobel Prize for cancer research was awarded to James Allison and Tasuku Honjo. (The main cause of cancer is the accumulation of errors in DNA. So the topic of cancer research is closely related to research on aging.) 2018 The World Health Organization included in the international classification of diseases ICD-11 a special additional code XT9T, signaling the relationship of a disease with age. Due to this, after the final approval of the ICD-11 in May 2019, aging began to be officially recognized as a fundamental factor that increases the risk of diseases, the severity of their course and the difficulty of treatment. ==== 2019 ==== The lifespan of Caenorhabditis elegans (free-living nematodes) was increased by 5–6 times (by 400–500%) using simultaneous impact in IIS and TOR pathways. This is equivalent to how a human would live 400–500 years. Scientists at the Mayo Clinic report the first successful use of senolytics, a new class of drug with potential anti-aging benefits, to remove senescent cells from human patients with a
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kidney disease. By combining doses of lithium, trametinib and rapamycin into a single treatment, researchers extend the lifespan of fruit flies (Drosophila) by 48%. Researchers at Harvard Medical School identify a link between neural activity and human longevity. Neural excitation is linked to shorter life, while suppression of overactivity appears to extend lifespan. Scientists in Japan use single-cell RNA analysis to find that supercentenarians have an excess of cytotoxic CD4 T-cells, a type of immune cell. ==== 2020 ==== Scientists report, using public biological data on 1.75 m people with known lifespans overall, to have identified 10 genomic loci which appear to intrinsically influence healthspan, lifespan, and longevity – of which half have not been reported previously at genome-wide significance and most being associated with cardiovascular disease – as well as haem metabolism as a promising candidate for further research within the field. Scientists report that after mice exercise their livers secrete the protein GPLD1, which is also elevated in elderly humans who exercise regularly, that this is associated with improved cognitive function in aged mice and that increasing the amount of GPLD1 produced by the mouse liver in old mice could yield many benefits of regular exercise for their brains – such as increased BDNF-levels, neurogenesis, and improved cognitive functioning in tests. Scientists report that yeast cells of the same genetic material and within the same environment age in two distinct ways, describe a biomolecular mechanism that can determine which process dominates during aging and genetically engineer a novel aging route with substantially extended lifespan. Reprogramming progress Scientists show that expression of nuclear reprogramming factors can lead to rapid and broad amelioration of cellular aging. A study shows that reprogramming induced with the OSK-genes can restore youthful epigenetic patterns as well as revert age-related vision loss. ==== 2021 ====
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Researchers report that myeloid cells are drivers of a maladaptive inflammation element of brain-ageing in mice and that this can be reversed or prevented via inhibition of their EP2 signalling. A randomized clinical trial demonstrates that a combination therapy of a short (two months) intervention of diet, phytonutrient and probiotics supplementation, exercise, relaxation and further lifestyle changes can lead to substantial decrease of the Horvath DNAmAge Epigenetic clock epigenetic aging biomarker in healthy adults and that such may therefore be, measurable, DNA methylome rejuvenation guidance. Scientists report alternative approach to senolytics for removing senescent cells: invariant NKT (iNKT) cells. Scientists demonstrate a tool to calculate a person's inflammatory age (iAge) based on patterns of systemic age-related inflammation and identify cytokine CXCL9 as a key suppression target. A study indicates gut microbiomes with large amounts of microbes capable of generating unique secondary bile acids are a key element of centenarians' longevity. Scientists identify genetic determinants of ovarian ageing and possible effects of extending fertility in women. Scientists show that transplantation of fecal microbiota from young donor mice into aged recipient mice substantially rejuvenates the brains of the latter, complementing similar results of a 2020 study. A study highlight the importance of extending healthspans, not just lifespans and especially as life expectancy rises and demographics shift. Biological aging or the healthspan-lifespan gap (LHG) comes with a great cost burden to society, including potentially rising health care costs (also depending on types and costs of treatments). Scientists have noted that "[c]hronic diseases of aging are increasing and are inflicting untold costs on human quality of life". Further reasons to prioritize healthspans as much as lifespans include global quality of life or wellbeing. A scientific review concludes that accumulating data suggests dietary restriction (DR) – mainly intermittent fasting and caloric restriction – results in
|
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"page_id": 67572411,
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many of the same beneficial changes in adult humans as in studied organisms, potentially increasing health- and lifespan. A review published a few days later provides an overview of DR as an intervention and develops a framework for a proposed field of "precision nutrigeroscience". A study published a few days later identifies circadian-regulated autophagy as a critical contributor to intermittent time-restricted fasting-mediated lifespan extension in Drosophila and suggests that only certain forms of and/or combinations with intermittent fasting – intervals during which no food but only e.g. water and tea/coffee are ingested – may be effective beyond the benefits of healthy body weight. Scientists show that and how the flavonoid Procyanidin C1 of the antioxidant grape seed extract increases the health- and lifespan of mice. A vaccine to remove senescent cells, a key driver of the aging process, is demonstrated in mice by researchers from Japan. The American biotechnology company Altos Labs, which focuses on life extension research, is founded. ==== 2022 ==== Nutrition-related results A study integrates meta-analyses and data in a tool that shows populations' relative general life extension potentials of different food groups according to this available data, mostly consisting of observational studies. Results from the first controlled trial of caloric restriction in healthy non-obese humans, CALERIE, are published, confirming benefits and identifying a key protein that could be harnessed to extend health in humans, PLA2G7. A comprehensive review reaffirms likely beneficial health effects with links to health/life extension of cycles of caloric restriction and intermittent fasting as well as reducing meat consumption in humans. It identifies issues with contemporary nutrition research approaches, proposing a multi-pillar approach, and summarizes findings towards constructing – multi-system-considering and at least age-personalized dynamic – refined longevity diets and proposes inclusion of such in standard preventive healthcare. A study demonstrates that a
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"page_id": 67572411,
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30% caloric restriction extended life spans of male C57BL/6J mice by 10% but when combined with daily intermittent fasting and eating during the most active time of the day it extended life span by 35%. A study shows that 50+ aged users of the dietary program SNAP "had about 2 fewer years of cognitive aging over a 10-year period compared with non-users" despite it having nearly no conditions for the sustainability and healthiness of the food products purchased with the coupons (or coupon-credits). A cohort study indicates dietary intakes of total flavonols – and at least kaempferol- and quercetin-containing foods in specific – may substantially decrease decline in multiple cognitive abilities with older age, showing a difference of "0.4 units per decade" between 5 mg and 15 mg intakes. A paywalled study reports higher percentage of daily energy consumption of ultra-processed foods, such as white bread or instant noodles, was associated with faster cognitive decline in aging. Differences can be as large or larger than a 28% faster rate of global cognitive decline. Pharmaceutical/supplemental intervention-related results Researchers report that the widely used supplements glycine and NAC when combined as "GlyNAC", which previously showed various beneficial effects in humans i.a. in a small trial by the authors, can extend lifespan by 24% in mice when taken at old age. Biomedical gerontologists demonstrate a mechanism of anti-aging senolytics, in particular of Dasatinib plus Quercetin (D+Q) – an increase of α-Klotho as shown in mice, human cells and in a human trial. A study reports that in model animals, treatment with rapamycin – which typically has negative side-effects – for a limited timespan extended lifespan as much as life-long administration started at the same age and that it was most effective during early adulthood. Biological and biotechnical rejuvenation-related results A new cellular rejuvenation
|
{
"page_id": 67572411,
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therapy of bursts of iPSC reprogramming is reported, which can reverse aspects of aging in mice, without causing cancer or other health problems. Scientists reversed aging in human skin cells for over 30 years by partially reprogramming them with the Yamanaka factors, working better than previous reprogramming methods. Bioresearchers demonstrate an in vitro method (MPTR) for rejuvenation (including the transcriptome and epigenome) reprogramming in which fibroblast skin cells temporarily lose their cell identity. Scientists report the key molecular mechanisms of rejuvenation they found in a comparison of the newly presented genomes of the biologically immortal T. dohrnii and a similar but non-rejuvenating jellyfish, involving e.g. DNA replication and repair, and stem cell renewal. A first spatiotemporal map reveals key insights about axolotl brain regeneration. Axolotls retain regenerative capacity in their aging throughout their lives. It is thought that by "understanding the mechanisms of regeneration, we eventually will be able to enhance our intrinsic regenerative abilities in order to slow and even reverse the damage of aging." Scientists report leprosy-causing bacteria viably regenerate and rejuvenate the liver in its armadillos hosts, which may enable novel human therapies. A study shows that infusing the nourishing cerebrospinal fluid from around brain cells of young mice into aged brains rejuvenates aspects of the brain, identifying FGF17 as a key target for potential therapeutics such as of anti-aging. A study shows the clonal diversity of stem cells that produce blood cells gets drastically reduced around age 70 to a faster-growing few, substantiating a novel theory of ageing which could enable healthy aging. A study shows that blood cells' loss of the Y chromosome in a subset of cells with age, reportedly affecting at least 40% of 70 years-old men to some degree, contributes to fibrosis, heart risks, and mortality in a causal way. Researchers describe
|
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"page_id": 67572411,
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a way by which the aging of select immune system T cells can be prevented or is slowed down, with relevance to life extension and making vaccines more durable. The discovery of "super neurons" in the entorhinal cortex of people over age 80 who show exceptional episodic memory is reported. Scientists report that some apparently senescent cells – which are targeted by anti-aging senolytics – are required for regeneration, and suggest tailoring senolytics to precisely target harmful senescent cells while leaving the ones involved in regeneration intact. A study indicates that aging shifts activity toward short genes or shorter transcript length and that this can be countered by interventions. Scientists report that sphingolipids accumulate in muscle during aging whose genetic inhibition or ceramide-blockers such as myriocin could counteract, reducing associated muscle loss. By stimulating (or charging) genetically engineered roundworm mitochondria with light, researchers show that halting the decline in mitochondrial membrane potential can slow aging. It was proposed to expand the list of the nine hallmarks of aging with five more. Saudi Arabia has started a not-for-profit organization called "the Hevolution Foundation" with budget $1 billion per year for developing anti-aging technology. ==== 2023 ==== Nutrition-related results A study reports results of the first longevity caloric restriction (CR) trial, CALERIE, finding that two years of nonintermittent CR slowed the pace of aging as measured by one of three aging clocks (modest DunedinPACE effects). Development and application of aging clocks and combination therapies A study reports the development of deep learning software using anatomic magnetic resonance images to estimate brain age with the highest accuracy for AI so far, including detecting early signs of Alzheimer's disease and varying neuroanatomical patterns of neurological aging. A study shows DNA methylation aging clocks could be useful indicators of health while social factors – such
|
{
"page_id": 67572411,
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as health behaviors and poverty – are at least as good predictors and e.g. can better predict cognitive functioning. Around February, Bryan Johnson's Project Blueprint for one of the first comprehensive, possibly largely public, self-experimentations of a comprehensive combination therapy informed by the large scientific corpus on the topic and organ measurements to maximally reverse biological age and (epigenetic) aging markers achieves substantial media attention, with such activities previously largely reserved to biohackers without resources and means to evaluate effects. The pan-mammalian epigenetic clock is a molecular biomarker designed to measure the age of all mammalian tissues and species using cytosine methylation in highly conserved DNA regions. A study indicates chest radiographs evaluated using AI could be a performant biomarker for aging clocks. A study using plasma proteomics aging clocks suggests nearly 20% of the population may show strongly accelerated age in one of 11 major organs, which it links to higher mortality risk. Biological and biotechnical rejuvenation-related results In January, a team led by David Sinclair shows in a 13-year-long international study how DNA breaks or epigenetic damage are a major driver of epigenetic change, and how the loss of epigenetic information is a cause of aging in mammals. It concluded that the loss of epigenetic information can drive aging independently of changes to the genetic code, suggesting that epigenetic change is a primary driver of aging in mammals. Using a treatment based on Yamanaka factors, they demonstrate an ability to drive aging in both the forward and reverse directions in mice. In a preprint, another team of researchers of the biotechnology company Rejuvenate Bio also reports the use of Yamanaka-reprogramming to modestly extend the lives of elderly mice. However, if it was also applicable to humans, risks may include the formation of cancer. In July, the David Sinclair
|
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"page_id": 67572411,
"source": null,
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team at Harvard Medical School release a study that claims to have discovered the first known chemical approach to reprogram cells to a younger state by delivering the Yamanaka factors directly, whereas previously this had only been achievable via gene therapy. A study indicates factors contributing to the longevity of long-living organisms can be transferred between species, particularly from naked mole-rats to mice. Chemical intervention-related results First senolytics discovered using artificial intelligence: Teams from the University of Edinburgh and the Massachusetts Institute of Technology independently report the discovery of senolytics using artificial intelligence for screening large chemical libraries. The works reported compounds of comparable efficacy and increased potency than other known senolytics. A study identifies low levels of taurine, which declines with age, as a driver of the aging process and suggests that taurine supplements may increase lifespan. Ora Biomedical announces the "million molecule challenge", an effort to assess 1 million potential longevity interventions within five years using artificial intelligence. A study suggests chemical alternatives to age reversal via Yamanaka factors gene therapy are feasible via early in vitro fibroblasts data. These results have not yet been validated in an animal and via more reliable "improvements in age-related health metrics or lifespan". Subcutaneous administration of longevity factor α-klotho enhanced cognition in old rhesus macaques. In a paywalled review, the authors of a heavily cited paper on the hallmarks of aging update the set of proposed hallmarks after a decade. A review with overlapping authors merge or link various hallmarks of cancer with those of aging. A study concludes that retroviruses in the human genomes can become awakened from dormant states and, in senescent cells and aged tissue, contribute to aging which can be blocked by neutralizing antibodies, resulting in improved function. A study by Columbia University researchers suggests hypermetabolism in
|
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cells due to impaired mitochondria is a driver of aging. A previously unknown cell mechanism involved in aging is discovered, which explains how cells 'remember' their identity when they divide – the cells' so-called epigenetic memory. A team of scientists from New York University identifies a potential cause of greying hair with age as the failure of melanocyte stem cells to mature with age. The study was carried out using mice, which have identical cells for their fur. According to the research team, the results could provide a basis for reversing the hair greying process. A study affirms and explains why a moderate decrease in body temperature extends lifespan. A study finds that human organs may age at different rates in some individuals, finding that nearly 20% of the 5,676 adults screened showed signs of accelerated aging in one organ and that 1.7% had more than one organ in a state of accelerated aging. By publishing virome-related results, researchers close a major gap in the acceleratingly accumulating research into centenarians' microbiome characteristics for life extension. Scientists at the University of Colorado report what they believe to be the primary mechanism behind cognitive decline in aging, the mis-regulation of the brain protein CaMKII. Three studies indicate platelets, including or especially FF4, are exerkines with health- and life-extension-potential that rejuvenate aging brains of mice. ==== 2024 ==== Researchers demonstrate antibody-mediated depletion of myeloid-biased hematopoietic stem cells against immune system aging with mice. An experiment by researchers at Imperial College London, the MRC London Institute of Medical Sciences, and Duke–NUS Medical School found that reduction in levels of the protein interleukin 11, which increases in the body with age and in excess is responsible for increased inflammation, reversed some aspects of aging in mice. The experiment, which involved genetically engineering some mice to
|
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block the production of the protein and allowing others to reach middle age before giving them a drug to eliminate it from their bodies, increased their lifespans by 20–25% and reversed numerous effects of aging. Precious3GPT, an artificial intelligence model designed to assist in aging research and drug discovery, is launched. A study by scientists at Stanford University found that rather than being a solely gradual and linear process, aging accelerates dramatically at two points in a human lifetime. The study, which tracked thousands of different molecules in 108 people aged between 25 and 75, found that age-related changes rise substantially in two waves, with the first occurring at around age 44 and the second at around age 60. Researchers at the Institute for Research in Biomedicine demonstrated that senescent cells release mt-dsRNA into the cytosol driving the SASP via RIGI/MDA5/MAVS/MFN1, and in turn are hypersensitive to mt-dsRNA-driven inflammation due to reduced levels of PNPT1/ADAR1. Moreover, senescent cells within fibrotic and aged tissues also present increased dsRNA foci, and inhibition of mitochondrial RNA polymerase reduces systemic inflammation associated to senescence. ==== 2025 ==== UPF1 was found to decline significantly during cellular senescence. The findings suggest that the fall in UPF1 accelerates senescence by slowing down nonsense-mediated mRNA decay. The study was conducted by scientists at Chungnam National University, the Korea Research Institute of Bioscience and Biotechnology, the Korea Advanced Institute of Science and Technology, and the US National Institute on Aging. Researchers at RWTH Aachen University discover that four senolytic compounds – JQ1, RG7112, nutlin-3a, and AMG232 – can decrease epigenetic age in in vitro blood samples. Researchers at the University of Osaka discovered that the protein AP2A1 may regulate cellular senescence, finding that suppressing the protein in older cells reversed senescence and promoted rejuvenation, whereas overexpression of the protein
|
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"page_id": 67572411,
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in young cells advanced senescence. A study by scientists at University College London, Stanford University, Inserm, and the University of Helsinki found that accelerated aging in specific organs could be predictors for diseases across the entire body, not just those affecting that particular organ. A study at the University of Texas at Austin identified the exposure of osteocytes to senescent cells as a key driver of aging in bones. == See also == Longevity escape velocity Life extension Rejuvenation Biogerontology === Fields not included === Research domains related or part of senescence research currently not fully included in the timeline: Senolytic Establishments of new research-conducting organizations, especially companies (see template at the bottom) Research into centenarians Ageing research projects and prizes === Excluded fields of research === Notable events in these fields of research that relate to life extension and healthspan are currently deliberately not included in this timeline History of nutritional science – progress in general health- and lifespan-related nutritional science List of causes of death by rate – such as R&D on the reduction of environmental toxins Years of potential life lost (YPLL) and Loss of life expectancy (LLE) General medicine and preventive healthcare and interventions against any specific aging-related disease Progress in tools and knowledge that can be used for anti-aging purposes such as CRISPR gene editing General regeneration in humans, organ printing and xenotransplantation progress Research about sustained brain health in general Maintaining health – conventional ways of maintaining and protecting health for life extension Health effects of exercise Neurobiological effects of physical exercise Public health / health policy including environmental policy and consumer protection == References == == Further reading == == External links == www.longevityhistory.com — history of aging research
|
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The aditus to mastoid antrum (otomastoid foramen) is a large, irregular opening upon the posterior wall of the tympanic cavity by which the mastoid antrum (situated posteriorly) communicates with the epitympanic recess of the tympanic cavity (situated anteriorly). The walls of the antrum are lined by mucosa which is continuous with that lining the mastoid cells and tympanic cavity. The medial wall of the aditus features a ridge created by the underlying facial canal, and a bulge created by the underlying ampulla of the lateral semicircular canal. The short limb of incus is lodged in a shallow fossa upon the posterior wall of the tympanic cavity just inferior to the aditus. The pyramidal eminence is situated inferior to the aditus. == See also == Aditus == References == == External links == Description at umich.edu http://www.dartmouth.edu/~humananatomy/figures/chapter_44/44-5.HTM Archived 2015-09-23 at the Wayback Machine
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{
"page_id": 6165180,
"source": null,
"title": "Aditus to mastoid antrum"
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Aminopropane may refer to: Propylamine (1-aminopropane) Isopropylamine (2-aminopropane)
|
{
"page_id": 23728830,
"source": null,
"title": "Aminopropane"
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|
Professor Bruce Harold John McKellar (born 1941) is an Australian theoretical particle physicist who is Honorary Professorial Fellow at the Centre of Excellence for Particle Physics at the Terascale (CoEPP) in the School of Physics at The University of Melbourne. The International Union of Pure and Applied Physics (IUPAP) elected him as its President-Designate in 2012. In November 2014 McKellar became President of IUPAP, the first-ever Australian to take on this role. McKellar is a theoretical particle physicist who is known for his work on particle physics and many other fields such as nuclear physics and cosmology. His other work has had applications in photography, atmospherics physics and geophysics, as well as implications for pure mathematics. On Australia Day (26 January 2014), McKellar was appointed a Companion of the Order of Australia (AC) by Governor-General Quentin Bryce, for his service to science, particularly theoretical physics, as an academic, educator and researcher, through seminal contributions to scientific development organisations, and as an author and mentor. The AC is Australia's highest civilian honour. == Early years and education == McKellar grew up in Bedgerabong in NSW, attending Bedgerabong Primary School which was then a one teacher school. His father was the teacher. He then attended Forbes High School before moving to Sydney at 16 to study a Bachelor of Science at the University of Sydney, which he completed with First Class Honours and the University Medal for Physics. He received his PhD in the University of Sydney in 1965, and a Doctor of Science from the University of Melbourne in 1976. == Academic career == Immediately on completion of his PhD, McKellar was appointed as lecturer at the University of Sydney. In 1965, McKellar was invited by J. Robert Oppenheimer to become a member of the Institute for Advanced Study, Princeton, USA,
|
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"title": "Bruce McKellar"
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which he undertook from 1966 to 1968. He then returned to University of Sydney. In 1972, at the age of 30, McKellar was appointed as the Professor of Theoretical Physics at Melbourne University. He retired from this role in 2007. He has held visiting positions at the French Atomic Energy Commission, Saclay (France), the TRIUMF Laboratories (Canada), the University of Washington (Seattle United States), the Los Alamos Laboratory (United States), CERN (Switzerland), the Yukawa Institute (Japan), the National Taiwan University, the National University of Singapore, the Australian National University and the University of Adelaide. At Princeton McKellar began his work on weak interactions, calculating the parity violation in expected in nuclei. He also started his work on three and many body nuclear forces. It was characteristic of this work that he was applying the current algebra techniques of particle physics to obtain results about nuclei. During his time at the University of Melbourne, McKellar and his collaborators published his definitive study on three nucleon forces, famously known as the "Tucson-Melbourne" force. His work on weak interactions led to calculation of the electric dipole moments expected for the nucleon and atoms in various models of these interactions. This work then evolved into studies of related effects in the B meson system. McKellar and his students also did foundational work on the behaviour of neutrinos propagating through a dense background of neutrinos as one finds in the early universe. He is well known for the "He McKellar Wilkens" phase, a seminal quantum physics result predicted by He and McKellar, and Wilkens (independently) in 1993–94. McKellar has made significant contribution to the development of the study of physics in Australia. He was elected a Fellow of the Australian Academy of Science in 1987, was its Vice President for Physical Sciences from 2000–2004 and
|
{
"page_id": 46273214,
"source": null,
"title": "Bruce McKellar"
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|
its Foreign Secretary from 2004–2006. He was a founding member of the Australian Research Council, playing a key role in both its establishment and development. McKellar actively facilitates physics research, policy development and international collaboration globally, especially in the Asia-Pacific Region. He served on the board of trustees of the sia Pacific Centre for Theoretical Physics and on the Council of the Association of Asia Pacific Physical Societies for many years. He chaired the Regional Committee for Asia and the Pacific of the International Council for Science (ICSU) (2009–2011), as well as the Australia and New Zealand Association for the Advancement of Science (ANZAAS) (1992–1998). McKellar is a Fellow of the Australian Institute of Physics, the Institute of Physics (UK), the American Physical Society, and the Australian Academy of Science. == Awards and honours == 2014: Companion of the Order of Australia 2009: Matthew Flinders Medal and Lecture, Australian Academy of Science 2006: Harrie Massey Medal and Prize, Institute of Physics (UK) and the Australian Institute of Physics 2001: Centenary Medal 1992: Walter Boas Medal, Australian Institute of Physics 1991: Thomas Ranken Lyle Medal, Australian Academy of Science 1987: Fellow of the Australian Academy of Science 1977: Research Medal, Royal Society of Victoria 1973: Pawsey Medal, Australian Academy of Science 1962: University Medal, University of Sydney == Personal life == Bruce McKellar married Loris Huckel in 1963. They have 2 children and 4 grandchildren and live in Melbourne, Australia. == Selected publications == McKELLAR, B.H.J. — The One Pion Exchange Contribution to the Weak Parity Violating Nucleon-Nucleon Potential. Physics Letters 26B: 107 – 108 (1967). McKELLAR, B.H.J. and RAJARAMAN, R. — Three Body Forces in Nuclear Matter. Physical Review Letters 21: 450 – 453 (1968). LASSEY, K.R. and McKELLAR, B.H.J. — Parity Non Conservation in (n,p) Capture at Thermal Energies:
|
{
"page_id": 46273214,
"source": null,
"title": "Bruce McKellar"
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|
The influence of Strong and Weak Interactions. Nuclear Physics A 260: 413 – 445 (1976). COON, S.A., SCADRON, M.D., McNAMEE, P.C., BARRETT, B.R., BLATT, D.W.E., and McKELLAR, B.H.J. — The Two Pion Exchange Three Nucleon Potential and Nuclear Matter. Nuclear Physics A 317: 242 — 287 (1979). This is the Tucson Melbourne Force paper. McKELLAR, B.H.J. — The Influence of Mixing of Finite Mass Neutrinos on Beta Decay Spectra. Physics Letters 97B: 93 – 94 (1980). McKELLAR, B.H.J., and GIBSON, B.F. — Nonmesonic decay of Heavy Λ-Hypernuclei. Physical Review C 30: 322 – 330 (1984) R.D.C. MILLER, and McKELLAR, B.H.J. — Effective Field Theory and Weak Non Leptonic Interactions. Physics Reports 106: 169 — 296 (1984). McKELLAR, B.H.J., CHOUDHURY, S.R., HE, X-G and PAKVASA, S. — The Neutron Electric Dipole Moment in the Standard KM Model. Physics Letters 197 B: 556 – 560 (1987). HE, X.-G., McKELLAR, B.H.J. and PAKVASA, S. — The Neutron Electric Dipole Moment. International Journal of Modern Physics A 4: 5011 – 5046 (1989), erratum A6: 1063 (1991) HE, XIAO-GANG, and McKELLAR, B.H.J. — Topological Phase Due to Electric Dipole Moment and Magnetic Monopole Interaction. Physical Review A 47: 3424 – 3245 (1993) McKELLAR, BRUCE H.J. and THOMSON, M.J. — Oscillating Neutrinos in the Early Universe. Physical Review D 49: 2710 – 2728 (1994) STEPHENSON, G. J. Jr, GOLDMAN T., and McKELLAR, B. H. J. — Neutrino Clouds. International Journal of Modern Physics A 13, 2765 – 2790 (1998) HE, X.-G., McKELLAR, B.H.J. Hadron decay amplitudes from B ---> K π and B ---> π π decays, ArXiv:hep-ph/0410098; (2004). == References == == External links == ARC Centre of Excellence for Particle Physics International Union of Pure and Applied Physics Scientific publications of Bruce McKellar on INSPIRE-HEP
|
{
"page_id": 46273214,
"source": null,
"title": "Bruce McKellar"
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|
COLD-PCR (co-amplification at lower denaturation temperature PCR) is a modified polymerase chain reaction (PCR) protocol that enriches variant alleles from a mixture of wildtype and mutation-containing DNA. The ability to preferentially amplify and identify minority alleles and low-level somatic DNA mutations in the presence of excess wildtype alleles is useful for the detection of mutations. Detection of mutations is important in the case of early cancer detection from tissue biopsies and body fluids such as blood plasma or serum, assessment of residual disease after surgery or chemotherapy, disease staging and molecular profiling for prognosis or tailoring therapy to individual patients, and monitoring of therapy outcome and cancer remission or relapse. Common PCR will amplify both the major (wildtype) and minor (mutant) alleles with the same efficiency, occluding the ability to easily detect the presence of low-level mutations. The capacity to detect a mutation in a mixture of variant/wildtype DNA is valuable because this mixture of variant DNAs can occur when provided with a heterogeneous sample – as is often the case with cancer biopsies. Currently, traditional PCR is used in tandem with a number of different downstream assays for genotyping or the detection of somatic mutations. These can include the use of amplified DNA for RFLP analysis, MALDI-TOF (matrix-assisted laser-desorption–time-of-flight) genotyping, or direct sequencing for detection of mutations by Sanger sequencing or pyrosequencing. Replacing traditional PCR with COLD-PCR for these downstream assays will increase the reliability in detecting mutations from mixed samples, including tumors and body fluids. == Method overviews == The underlying principle of COLD-PCR is that single nucleotide mismatches will slightly alter the melting temperature (Tm) of the double-stranded DNA. Depending on the sequence context and position of the mismatch, Tm changes of 0.2–1.5 °C (0.36–2.7 °F) are common for sequences up to 200bp or higher. Knowing this
|
{
"page_id": 26415811,
"source": null,
"title": "COLD-PCR"
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|
the authors of the protocol took advantage of two observations: Each double-stranded DNA has a 'critical temperature' (Tc) lower than its Tm. The PCR amplification efficiency drops measurably below the Tc. The Tc is dependent on DNA sequence. Two template DNA fragments differing by only one or two nucleotide mismatches will have different amplification efficiencies if the denaturation step of PCR is set to the Tc. Keeping these principles in mind the authors developed the following general protocol: Denaturation stage. DNA is denatured at a high temperature – usually 94 °C (201 °F). Intermediate annealing stage. Set an intermediate annealing temperature that allows hybridization of mutant and wildtype allele DNA to one another. Because the mutant allele DNA forms the minority of DNA in the mixture they will be more likely to form mismatch heteroduplex DNA with the wildtype DNA. Melting stage. These heteroduplexes will more readily melt at lower temperatures. Hence they are selectively denatured at the Tc. Primer annealing stage. The homo-duplex DNA will preferentially remain double stranded and not be available for primer annealing. Extension stage. The DNA polymerase will extend complementary to the template DNA. Since the heteroduplex DNA is used as template, a larger proportion of minor variant DNA will be amplified and be available for subsequent rounds of PCR. There are two forms of COLD-PCR that have been developed to date. Full COLD-PCR and fast COLD-PCR. === Full === Full COLD-PCR is identical to the protocol outlined above. These five stages are used for each round of amplification. === Fast === Fast COLD-PCR differs from Full COLD-PCR in that the denaturation and intermediate annealing stages are skipped. This is because, in some cases, the preferential amplification of the mutant DNA is so great that ensuring the formation of the mutant/wildtype heteroduplex DNA is not
|
{
"page_id": 26415811,
"source": null,
"title": "COLD-PCR"
}
|
needed. Thus the denaturation can occur at the Tc, proceed to primer annealing, and then polymerase-mediated extension. Each round of amplification will include these three stages in that order. By utilizing the lower denaturation temperature, the reaction will discriminate toward the products with the lower Tm – i.e. the variant alleles. Fast COLD-PCR produces much faster results due to the shortened protocol, while Full COLD-PCR is essential for amplification of all possible mutations in the starting mixture of DNA. Two-round COLD-PCR is a modified version of Fast COLD-PCR. During the second round of Fast COLD-PCR nested primers are used. This improves the sensitivity of mutation detection compared to one-round Fast COLD-PCR. == Uses == COLD-PCR has been used to improve the reliability of a number of different assays that traditionally use conventional PCR. === RFLP === A restriction fragment length polymorphism results in the cleavage (or absence thereof) of DNA for a specific mutation by a selected restriction enzyme that will not cleave the wildtype DNA. In a study using a mixture of wildtype and mutation containing DNA amplified by regular PCR or COLD-PCR, COLD-PCR preceding RFLP analysis was shown to improve the mutation detection by 10-20 fold. === Sanger sequencing === Sanger sequencing recently was used to evaluate the enrichment of mutant DNA from a mixture of 1:20 mutant:wildtype DNA. The variant DNA containing a mutation was obtained from a breast cancer cell line known to contain p53 mutations. Comparison of Sanger sequencing chromatograms indicated that the mutant allele was enriched 13 fold when COLD-PCR was used compared to traditional PCR alone. This was determined by the size of the peaks on the chromatogram at the variant allele location. As well, COLD-PCR was used to detect p53 mutations from lung-adenocarcinoma samples. The study was able to detect 8 low
|
{
"page_id": 26415811,
"source": null,
"title": "COLD-PCR"
}
|
level (under 20% abundance) mutations that would likely have been missed using conventional methods that don't enrich for variant sequence DNA. === Pyrosequencing === Similar to its use in direct Sanger sequencing, with pyrosequencing COLD-PCR was shown to be capable of detecting mutations that had a prevalence 0.5–1% from the samples used. COLD-PCR was used to detect p53 and KRAS mutations by pyrosequencing, and was shown to outperform conventional PCR in both cases. === MALDI-TOF === The same research group that developed COLD-PCR and used it to compare the sensitivity of regular PCR for genotyping with direct Sanger sequencing, RFLP, and pyrosequencing, also ran a similar study using MALDI-TOF as a downstream application for detecting mutations. Their results indicated that COLD-PCR could enrich mutation sequences from a mixture of DNA by 10–100 fold and that mutations with an initial prevalence of 0.1–0.5% would be detectable. Compared to the 5–10% low-level detection rate expected with traditional PCR. === QPCR === COLD-PCR run on a quantitative PCR machine, using TaqMan probes specific for a mutation, was shown to increase the measured difference between mutant and wildtype samples. == Advantages == Single-step method capable of enriching both known and unknown minority alleles irrespective of mutation type and position Does not require extra costly reagents or specialized machinery Better than conventional PCR for the detection of mutations in a mixed sample Does not significantly increase experiment run time compared to conventional PCR == Disadvantages == Optimal Tc must be measured and determined for each amplicon, adding an extra step to conventional PCR-based procedures Requirement for precise denaturation temperature control during PCR to within ± 0.3 °C (0.54 °F) A suitable critical temperature may not be available that differentiates between mutant and wildtype DNA sequences Restricted to analyzing sequences smaller than approximately 200bp Vulnerable to
|
{
"page_id": 26415811,
"source": null,
"title": "COLD-PCR"
}
|
polymerase-introduced errors Variable overall mutation enrichment dependent on DNA position and nucleotide substitution No guarantee that all low-level mutations will be preferentially enriched == History == COLD-PCR was originally described by Li et al. in a Nature Medicine paper published in 2008 from Mike Makrigiorgos's lab group at the Dana Farber Cancer Institute of Harvard Medical School. As summarized above, the technology has been used in a number of proof-of-principle experiments and medical research diagnostic experiments. Recently, the COLD-PCR technology has been licensed by Transgenomic, Inc. The licensing terms include the exclusive rights to commercialize the technology combined with Sanger sequencing. The plans are to develop commercial applications that will allow for rapid high-sensitivity detection of low-level somatic and mitochondrial DNA mutations. == Alternatives == Other technologies are available for the detection of minority DNA mutations, and these methods can be segregated into their ability to enrich for and detect either known or unknown mutations. == See also == PCR Genotyping Single-nucleotide polymorphism SNP genotyping == References ==
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{
"page_id": 26415811,
"source": null,
"title": "COLD-PCR"
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|
The void ratio ( e {\displaystyle e} ) of a mixture of solids and fluids (gases and liquids), or of a porous composite material such as concrete, is the ratio of the volume of the voids ( V V {\displaystyle V_{V}} ) filled by the fluids to the volume of all the solids ( V S {\displaystyle V_{S}} ). It is a dimensionless quantity in materials science and in soil science, and is closely related to the porosity (often noted as ϕ {\displaystyle \phi } , or η {\displaystyle {\eta }} , depending on the convention), the ratio of the volume of voids ( V V {\displaystyle V_{V}} ) to the total (or bulk) volume ( V T {\displaystyle V_{T}} ), as follows: e = V V V S = V V V T − V V = ϕ 1 − ϕ {\displaystyle e={\frac {V_{V}}{V_{S}}}={\frac {V_{V}}{V_{T}-V_{V}}}={\frac {\phi }{1-\phi }}} in which, for idealized porous media with a rigid and undeformable skeleton structure (i.e., without variation of total volume ( V T {\displaystyle V_{T}} ) when the water content of the sample changes (no expansion or swelling with the wetting of the sample); nor contraction or shrinking effect after drying of the sample), the total (or bulk) volume ( V T {\displaystyle V_{T}} ) of an ideal porous material is the sum of the volume of the solids ( V S {\displaystyle V_{S}} ) and the volume of voids ( V V {\displaystyle V_{V}} ): V T = V S + V V {\displaystyle V_{T}=V_{S}+V_{V}} (in a rock, or in a soil, this also assumes that the solid grains and the pore fluid are clearly separated, so swelling clay minerals such as smectite, montmorillonite, or bentonite containing bound water in their interlayer space are not considered here.) and ϕ = V
|
{
"page_id": 7934659,
"source": null,
"title": "Void ratio"
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|
V V T = V V V S + V V = e 1 + e {\displaystyle \phi ={\frac {V_{V}}{V_{T}}}={\frac {V_{V}}{V_{S}+V_{V}}}={\frac {e}{1+e}}} where e {\displaystyle e} is the void ratio, ϕ {\displaystyle \phi } is the porosity, VV is the volume of void-space (gases and liquids), VS is the volume of solids, and VT is the total (or bulk) volume. This figure is relevant in composites, in mining (particular with regard to the properties of tailings), and in soil science. In geotechnical engineering, it is considered one of the state variables of soils and represented by the symbol e {\displaystyle e} . Note that in geotechnical engineering, the symbol ϕ {\displaystyle \phi } usually represents the angle of shearing resistance, a shear strength (soil) parameter. Because of this, in soil science and geotechnics, these two equations are usually presented using η {\displaystyle {\eta }} for porosity: e = V V V S = V V V T − V V = n 1 − n {\displaystyle e={\frac {V_{V}}{V_{S}}}={\frac {V_{V}}{V_{T}-V_{V}}}={\frac {n}{1-{n}}}} and η = V V V T = V V V S + V V = e 1 + e {\displaystyle {\eta }={\frac {V_{V}}{V_{T}}}={\frac {V_{V}}{V_{S}+V_{V}}}={\frac {e}{1+e}}} where e {\displaystyle e} is the void ratio, η {\displaystyle {\eta }} is the porosity, VV is the volume of void-space (air and water), VS is the volume of solids, and VT is the total (or bulk) volume. == Applications in soil sciences and geomechanics == Control of the volume change tendency. Suppose the void ratio is high (loose soils). Under loading, voids in the soil skeleton tend to decrease (shrinkage), increasing the contact between adjacent particles and modifying the soil effective stress. The opposite situation, i. e. when the void ratio is relatively small (dense soils), indicates that the volume of the soil
|
{
"page_id": 7934659,
"source": null,
"title": "Void ratio"
}
|
is vulnerable to increase (swelling) under unloading – the smectite (montmorillonite, bentonite) partially dry clay particles present in an unsaturated soil can swell due to their hydration after contact with water (when the saturated/unsaturated conditions fluctuate in a soil). Control of the fluid hydraulic conductivity (ability of water movement through the soil). Loose soils show a high hydraulic conductivity, while dense soils are less permeable. Particle movement. Small, unbound particles can move relatively quickly through the larger open voids in loose soil. In contrast, in dense soil, finer particles cannot freely pass the smaller pores, which leads to the clogging of the porosity. == See also == Pore space in soil Void (composites) == References == == Further reading == Bates, R.L.; Jackson, J.A. (1987-10-15). Glossary of Geology, Third Edition – American Geological Institute, Alexandria. Amazon.com: Books 9780913312896. American Geological Institute. ISBN 0913312894. == External links ==
|
{
"page_id": 7934659,
"source": null,
"title": "Void ratio"
}
|
Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as well as the inanimate physical environment. It is the computed response of the system or organism to various stimuli or inputs, whether internal or external, conscious or subconscious, overt or covert, and voluntary or involuntary. While some behavior is produced in response to an organism's environment (extrinsic motivation), behavior can also be the product of intrinsic motivation, also referred to as "agency" or "free will". Taking a behavior informatics perspective, a behavior consists of actor, operation, interactions, and their properties. This can be represented as a behavior vector. == Models == === Biology === ==== Definition ==== Behavior may be defined as "the internally coordinated responses (actions or inactions) of whole living organisms (individuals or groups) to internal or external stimuli". A broader definition of behavior, applicable to plants and other organisms, is similar to the concept of phenotypic plasticity. It describes behavior as a response to an event or environment change during the course of the lifetime of an individual, differing from other physiological or biochemical changes that occur more rapidly, and excluding changes that are a result of development (ontogeny). Behaviour can be regarded as any action of an organism that changes its relationship to its environment. Behavior provides outputs from the organism to the environment. ==== Determination by genetics or the environment ==== Behaviors can be either innate or learned from the environment, or both, dependent on the organism. The more complex nervous systems (or brains) are, the more influence learning has on behavior. However, even in mammals, a large fraction of behavior is genetically determined. For instance, prairie voles tend to be
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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monogamous while, while meadow voles are more promiscuous, a difference that is strongly determined by a single gene, Avpr1a, encoding a receptor for the peptide hormone Vasopressin. === Human behavior === The endocrine system and the nervous system likely influence human behavior. Complexity in the behavior of an organism may be correlated to the complexity of its nervous system. Generally, organisms with more complex nervous systems have a greater capacity to learn new responses and thus adjust their behavior. === Animal behavior === Ethology is the scientific and objective study of animal behavior, usually with a focus on behavior under natural conditions, and viewing behavior as an evolutionarily adaptive trait. Behaviorism is a term that also describes the scientific and objective study of animal behavior, usually referring to measured responses to stimuli or trained behavioral responses in a laboratory context, without a particular emphasis on evolutionary adaptivity. == Consumer behavior == === Consumers behavior === Consumer behavior involves the processes consumers go through, and reactions they have towards products or services. It has to do with consumption, and the processes consumers go through around purchasing and consuming goods and services. Consumers recognize needs or wants, and go through a process to satisfy these needs. Consumer behavior is the process they go through as customers, which includes types of products purchased, amount spent, frequency of purchases and what influences them to make the purchase decision or not. Circumstances that influence consumer behaviour are varied, with contributions from both internal and external factors. Internal factors include attitudes, needs, motives, preferences and perceptual processes, whilst external factors include marketing activities, social and economic factors, and cultural aspects. Doctor Lars Perner of the University of Southern California claims that there are also physical factors that influence consumer behavior, for example, if a consumer is
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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hungry, then this physical feeling of hunger will influence them so that they go and purchase a sandwich to satisfy the hunger. === Consumer decision making === Lars Perner presents a model that outlines the decision-making process involved in consumer behaviour. The process initiates with the identification of a problem, wherein the consumer acknowledges an unsatisfied need or desire. Subsequently, the consumer proceeds to seek information, whereas for low-involvement products, the search tends to rely on internal resources, retrieving alternatives from memory. Conversely, for high-involvement products, the search is typically more extensive, involving activities like reviewing reports, reading reviews, or seeking recommendations from friends. The consumer will then evaluate his or her alternatives, comparing price, and quality, doing trade-offs between products, and narrowing down the choice by eliminating the less appealing products until there is one left. After this has been identified, the consumer will purchase the product. Finally, the consumer will evaluate the purchase decision, and the purchased product, bringing in factors such as value for money, quality of goods, and purchase experience. However, this logical process does not always happen this way, people are emotional and irrational creatures. People make decisions with emotion and then justify them with logic according to Robert Cialdini Ph.D. Psychology. === How the 4P's influence consumer behavior === The Marketing mix (4 P's) are a marketing tool and stand for Price, Promotion, Product, and Placement. Due to the significant impact of business-to-consumer marketing on consumer behavior, the four elements of the marketing mix, known as the 4 P's (product, price, place, and promotion), exert a notable influence on consumer behavior. The price of a good or service is largely determined by the market, as businesses will set their prices to be similar to that of other businesses so as to remain competitive whilst
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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|
making a profit. When market prices for a product are high, it will cause consumers to purchase less and use purchased goods for longer periods of time, meaning they are purchasing the product less often. Alternatively, when market prices for a product are low, consumers are more likely to purchase more of the product, and more often. The way that promotion influences consumer behavior has changed over time. In the past, large promotional campaigns and heavy advertising would convert into sales for a business, but nowadays businesses can have success on products with little or no advertising. This is due to the Internet and in particular social media. They rely on word of mouth from consumers using social media, and as products trend online, so sales increase as products effectively promote themselves. Thus, promotion by businesses does not necessarily result in consumer behavior trending towards purchasing products. The way that product influences consumer behavior is through consumer willingness to pay, and consumer preferences. This means that even if a company were to have a long history of products in the market, consumers will still pick a cheaper product over the company in question's product if it means they will pay less for something that is very similar. This is due to consumer willingness to pay, or their willingness to part with the money they have earned. The product also influences consumer behavior through customer preferences. For example, take Pepsi vs Coca-Cola, a Pepsi-drinker is less likely to purchase Coca-Cola, even if it is cheaper and more convenient. This is due to the preference of the consumer, and no matter how hard the opposing company tries they will not be able to force the customer to change their mind. Product placement in the modern era has little influence on consumer behavior,
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{
"page_id": 4805,
"source": null,
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due to the availability of goods online. If a customer can purchase a good from the comfort of their home instead of purchasing in-store, then the placement of products is not going to influence their purchase decision. == In management == Behavior outside of psychology includes === Organizational === In management, behaviors are associated with desired or undesired focuses. Managers generally note what the desired outcome is, but behavioral patterns can take over. These patterns are the reference to how often the desired behavior actually occurs. Before a behavior actually occurs, antecedents focus on the stimuli that influence the behavior that is about to happen. After the behavior occurs, consequences fall into place. Consequences consist of rewards or punishments. === Social behavior === Social behavior is behavior among two or more organisms within the same species, and encompasses any behavior in which one member affects the other. This is due to an interaction among those members. Social behavior can be seen as similar to an exchange of goods, with the expectation that when one gives, one will receive the same. This behavior can be affected by both the qualities of the individual and the environmental (situational) factors. Therefore, social behavior arises as a result of an interaction between the two—the organism and its environment. This means that, in regards to humans, social behavior can be determined by both the individual characteristics of the person, and the situation they are in. == Behavior informatics == Behavior informatics also called behavior computing, explores behavior intelligence and behavior insights from the informatics and computing perspectives. Different from applied behavior analysis from the psychological perspective, BI builds computational theories, systems and tools to qualitatively and quantitatively model, represent, analyze, and manage behaviors of individuals, groups and/or organizations. == Health == Health behavior refers to
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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a person's beliefs and actions regarding their health and well-being. Health behaviors are direct factors in maintaining a healthy lifestyle. Health behaviors are influenced by the social, cultural, and physical environments in which we live. They are shaped by individual choices and external constraints. Positive behaviors help promote health and prevent disease, while the opposite is true for risk behaviors. Health behaviors are early indicators of population health. Because of the time lag that often occurs between certain behaviors and the development of disease, these indicators may foreshadow the future burdens and benefits of health-risk and health-promoting behaviors. === Correlates === A variety of studies have examined the relationship between health behaviors and health outcomes (e.g., Blaxter 1990) and have demonstrated their role in both morbidity and mortality. These studies have identified seven features of lifestyle which were associated with lower morbidity and higher subsequent long-term survival (Belloc and Breslow 1972): Avoiding snacks Eating breakfast regularly Exercising regularly Maintaining a desirable body weight Moderate alcohol intake Not smoking Sleeping 7–8hrs per night Health behaviors impact upon individuals' quality of life, by delaying the onset of chronic disease and extending active lifespan. Smoking, alcohol consumption, diet, gaps in primary care services and low screening uptake are all significant determinants of poor health, and changing such behaviors should lead to improved health. For example, in US, Healthy People 2000, United States Department of Health and Human Services, lists increased physical activity, changes in nutrition and reductions in tobacco, alcohol and drug use as important for health promotion and disease prevention. === Treatment approach === Any interventions done are matched with the needs of each individual in an ethical and respected manner. Health belief model encourages increasing individuals' perceived susceptibility to negative health outcomes and making individuals aware of the severity of such
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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|
negative health behavior outcomes. E.g. through health promotion messages. In addition, the health belief model suggests the need to focus on the benefits of health behaviors and the fact that barriers to action are easily overcome. The theory of planned behavior suggests using persuasive messages for tackling behavioral beliefs to increase the readiness to perform a behavior, called intentions. The theory of planned behavior advocates the need to tackle normative beliefs and control beliefs in any attempt to change behavior. Challenging the normative beliefs is not enough but to follow through the intention with self-efficacy from individual's mastery in problem solving and task completion is important to bring about a positive change. Self efficacy is often cemented through standard persuasive techniques. == See also == == References == General Cao, L. (2014). Behavior Informatics: A New Perspective. IEEE Intelligent Systems (Trends and Controversies), 29(4): 62–80. Clemons, E. K. (2008). "How Information Changes Consumer Behavior and How Consumer Behavior Determines Corporate Strategy". Journal of Management Information Systems. 25 (2): 13–40. doi:10.2753/mis0742-1222250202. S2CID 16370526. Dowhan, D (2013). "Hitting Your Target". Marketing Insights. 35 (2): 32–38. Perner, L. (2008), Consumer behavior. University of Southern California, Marshall School of Business. Retrieved from http://www.consumerpsychologist.com/intro_Consumer_Behavior.html Szwacka-Mokrzycka, J (2015). "TRENDS IN CONSUMER behavior CHANGES. OVERVIEW OF CONCEPTS". Acta Scientiarum Polonorum. Oeconomia. 14 (3): 149–156. == Further reading == Bateson, P. (2017) behavior, Development and Evolution. Open Book Publishers, Cambridge. ISBN 978-1-78374-250-9. Plomin, Robert; DeFries, John C.; Knopik, Valerie S.; Neiderhiser, Jenae M. (24 September 2012). Behavioral Genetics. Shaun Purcell (Appendix: Statistical Methods in Behavioral Genetics). Worth Publishers. ISBN 978-1-4292-4215-8. Retrieved 4 September 2013. Flint, Jonathan; Greenspan, Ralph J.; Kendler, Kenneth S. (28 January 2010). How Genes Influence Behavior. Oxford University Press. ISBN 978-0-19-955990-9. == External links == What is behavior? Baby don't ask me, don't ask me,
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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no more at Earthling Nature. behaviorinformatics.org Links to review articles by Eric Turkheimer and co-authors on behavior research Links to IJCAI2013 tutorial on behavior informatics and computing
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{
"page_id": 4805,
"source": null,
"title": "Behavior"
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|
6-Acetyl-2,3,4,5-tetrahydropyridine is an aroma compound and flavor that gives baked goods such as white bread, popcorn, and tortillas their typical smell, together with its structural homolog 2-acetyl-1-pyrroline. 6-Acetyl-2,3,4,5-tetrahydropyridine and 2-acetyl-1-pyrroline are usually formed by Maillard reactions during heating of food. Both compounds have odor thresholds below 0.06 ng/L. == Structure and properties == 6-Acetyl-2,3,4,5-tetrahydropyridine is a substituted tetrahydropyridine and a cyclic imine as well as a ketone. The compound exists in a chemical equilibrium with its tautomer 6-acetyl-1,2,3,4-tetrahydropyridine that differs only by the position of the double bond in the tetrahydropyridine ring: == References ==
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{
"page_id": 15012549,
"source": null,
"title": "6-Acetyl-2,3,4,5-tetrahydropyridine"
}
|
Conpoy or dried scallop is a type of Cantonese dried seafood product that is made from the adductor muscle of scallops. The smell of conpoy is marine, pungent, and reminiscent of certain salt-cured meats. Its taste is rich in umami due to its high content of various free amino acids, such as glycine, alanine, and glutamic acid. It is also rich in nucleic acids such as inosinic acid, amino acid byproducts such as taurine, and minerals, such as calcium and zinc. Conpoy is produced by cooking raw scallops and then drying them. == Terminology == Conpoy is a loanword from the Cantonese pronunciation of 乾貝 (gōn bui), which literally means "dried shell(fish)". == Usage == In Hong Kong, conpoy from two types of scallops are common. Conpoy made from Atrina pectinata or gōng yìuh (江珧) from mainland China is small and milder in taste. Mizuhopecten yessoensis or sin bui (扇貝), a sea scallop imported from Japan (hotategai, 帆立貝 in Japanese), produces a conpoy that is stronger and richer in taste . As with many dried foods, conpoy was originally made as a way to preserve seafood in times of excess. In more recent times its use in cuisine has been elevated to gourmet status. Conpoy has a strong and distinctive flavor that can be easily identified when used in rice congee, stir fries, stews, and sauces. XO sauce, a seasoning used for frying vegetables or seafoods in Cantonese cuisine, contains significant quantities of conpoy. For example, the Lee Kum Kee formulation lists conpoy as the third ingredient on its label. == See also == == References ==
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{
"page_id": 463558,
"source": null,
"title": "Conpoy"
}
|
The RNA Tie Club was an informal scientific club, meant partly to be humorous, of select scientists who were interested in how proteins were synthesised from genes, specifically the genetic code. It was created by George Gamow upon a suggestion by James Watson in 1954 when the relationship between nucleic acids and amino acids in genetic information was unknown. The club consisted of 20 full members, each representing an amino acid, and four honorary members, representing the four nucleotides. The function of the club members was to think up possible solutions and share with the other members. The first important document of the RNA Tie Club was Francis Crick's adaptor hypothesis in 1955. Experimental work on the hypothesis led to the discovery of transfer RNA, a molecule that carries the key to genetic code. Most of the theoretical groundwork and preliminary experiments on the genetic code were done by the club members within a decade. However, the specific code was discovered by Marshall Nirenberg, a non-member, who received Nobel Prize in Physiology or Medicine in 1968 for the discovery. == History == === Background === In 1953, English biophysicist Francis Crick and American biologist James Watson, working together at the Cavendish Laboratory of the University of Cambridge, deduced the structure of DNA, the principal genetic material of organisms, thought to link genetic information in DNA to proteins. By 1954, it was becoming understood that the genetic information pathway involved DNA, RNA and proteins. However, the structure and nature of RNA were still a mystery (specific RNA molecules were not known until 1960), especially how RNA is involved in protein synthesis. Watson called this problem "the mystery of life" in his letter to Crick. Soviet-American physicist George Gamow at George Washington University suggested the first scheme for protein synthesis from DNA.
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{
"page_id": 26415816,
"source": null,
"title": "RNA Tie Club"
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|
In early 1954, he spent several days at Woods Hole on Cape Cod with Crick, Watson and Sydney Brenner, discussing genetics. Based on the Watson-Crick model, he proposed a "direct DNA template hypothesis" stating that proteins are synthesised directly from the double-stranded grooves of DNA. The four bases of DNA were assumed to synthesise 20 different amino acids as triplets with overlapping nucleotide sequences. He published the hypothesis in the 13 February 1954 issue of Nature, explaining:It seems to me that such translation procedure can be easily established by considering the 'key-and-lock' relation between various amino-acids, and the rhomb-shaped 'holes' formed by various nucleotides in the deoxyribonucleic acid chain... One can speculate that free amino-acids from the surrounding medium get caught into the 'holes' of deoxyribonucleic acid molecules, and thus unite into the corresponding peptide chains. === Foundation === In May 1954, Watson visited Gamow, who was on sabbatical at the University of California, Berkeley. While discussing Gamow's hypothesis, he suggested that they form a 20-member club to work out the genetic code. Gamow instantly came up with the RNA Tie Club to "solve the riddle of the RNA structure and to understand how it built proteins", adding the motto "do or die; or don't try." The club thus consisted of 20 eminent scientists, each of whom corresponded to an amino acid, plus four honorary members (S. Brenner, VAL. F. Lipmann, A. Szent-Gyorgyi, and another individual), one for each nucleotide. Each member received a woolen necktie having an embroidered helix, hence the name "RNA Tie Club". == Members == == The tie and tiepin == Members of the RNA Tie Club received a black wool-knit tie with a green and yellow RNA helix emblazoned on it. The original design of the tie came from Orgel, with the final pattern re-imagined
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{
"page_id": 26415816,
"source": null,
"title": "RNA Tie Club"
}
|
by Gamow. Gamow's tie pattern was delivered to a Los Angeles haberdasher on Colorado Avenue by Watson, with the shop tailor promising to make the ties for $4 each. Along with each tie, members of the club were to receive a golden tiepin with the three letter abbreviation of their club amino acid designation. Not all members may have received their pin. Gamow, however, wore his pin on several occasions, often causing confusion and questioning of why he was wearing the "wrong initials". == Successes == The RNA Tie Club never had a formal meeting of all its members. Members visited each other to discuss the scientific developments, usually involving cigars and alcohol. This allowed bonding and close friendships to develop among this scientific elite, and it turned out to be a breeding ground for creative ideas. The members mailed letters and preprints of articles to each other suggesting new concepts and ideas. === Number of nucleotides in a codon === Using mathematics, Gamow postulated that a nucleotide code consisting of three letters (triplets) would be enough to define all 20 amino acids. This concept is the basis of "codons", and set an upper and lower limit on their size. Gamow had simply estimated that the number of bases and their complementary pairs in a DNA strand could create 20 cavities for amino acids, meaning that 20 different amino acids could be involved in protein synthesis. He named this DNA–protein interaction the "diamond code." Although Gamow's premise that DNA directly synthesized proteins was proven wrong, the triplet code became the foundation of genetic code. === Codons === Sydney Brenner proposed the concept of the codon, the idea that three non-overlapping nucleotides could code for one amino acid. His proof involved statistics and experimental evidence from amino acid protein sequences. ===
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{
"page_id": 26415816,
"source": null,
"title": "RNA Tie Club"
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|
Adaptor hypothesis === Francis Crick proposed the "adaptor hypothesis" (a name given by Brenner) suggesting that some molecule ferried the amino acids around, and put them in the correct order corresponding to the nucleic acid sequence. The hypothesis contradicted Gamow's direct DNA template hypothesis, positing that DNA could not synthesise proteins directly, but instead requires other molecules, adaptors to convert the DNA sequences to amino acid sequences. He also suggested that there were such 20 separate adaptor molecules. This was later confirmed by Robert Holley and the adaptor molecules were named transfer RNAs (tRNAs). The typed paper distributed to the members of the RNA Tie Club in January 1955 as "On Degenerate Templates and the Adaptor Hypothesis: A Note for the RNA Tie Club" is described as "one of the most important unpublished articles in the history of science", and "the most famous unpublished paper in the annals of molecular biology." Watson recalled, "The most famous of these [unpublished] notes, by Francis, in time would totally change the way we thought about protein synthesis. === Personal successes === Six members of the RNA Tie Club became Nobel laureates: Richard Feynman, Melvin Calvin, James Watson, Max Delbruck, Francis Crick and Sydney Brenner. However, the ultimate goal of understanding and deciphering the code linking nucleic acids and amino acids was achieved by Marshall Nirenberg, who was not a member of the RNA Tie Club, and received the Nobel Prize in Physiology or Medicine in 1968 with Holley and Har Gobind Khorana. == References ==
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{
"page_id": 26415816,
"source": null,
"title": "RNA Tie Club"
}
|
In enzymology, an estradiol 17beta-dehydrogenase (EC 1.1.1.62) is an enzyme that catalyzes the chemical reaction estradiol-17beta + NAD(P)+ ⇌ {\displaystyle \rightleftharpoons } estrone + NAD(P)H + H+ The 3 substrates of this enzyme are estradiol-17beta, NAD+, and NADP+, whereas its 4 products are estrone, NADH, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is estradiol-17beta:NAD(P)+ 17-oxidoreductase. Other names in common use include 20alpha-hydroxysteroid dehydrogenase, 17beta,20alpha-hydroxysteroid dehydrogenase, 17beta-estradiol dehydrogenase, estradiol dehydrogenase, estrogen 17-oxidoreductase, and 17beta-HSD. This enzyme participates in androgen and estrogen metabolism. == Structural studies == As of late 2007, 29 structures have been solved for this class of enzymes, with PDB accession codes 1A27, 1BHS, 1DHT, 1EQU, 1FDS, 1FDT, 1FDU, 1FDV, 1FDW, 1GZ6, 1I5R, 1IKT, 1IOL, 1JTV, 1QYV, 1QYW, 1QYX, 1S1P, 1S1R, 1S2A, 1S2C, 1XF0, 1YB1, 1ZQ5, 2F38, 2FGB, 2HQ1, 2PD6, and 3DHE. == References == Kautsky MP, Hagerman DD (1970). "17β-Estradiol Dehydrogenase of Ovine Ovaries". J. Biol. Chem. 245 (8): 1978–84. doi:10.1016/S0021-9258(18)63194-1. PMID 4314937. Langer LJ, Alexander JA, Engel LL (1959). "Human Placental Estradiol-17β Dehydrogenase. II. Kinetics and substrate specificities". J. Biol. Chem. 234 (10): 2609–14. doi:10.1016/S0021-9258(18)69746-7. PMID 14413943.
|
{
"page_id": 13898437,
"source": null,
"title": "Estradiol 17beta-dehydrogenase"
}
|
The circuit topology of a folded linear polymer refers to the arrangement of its intra-molecular contacts. Examples of linear polymers with intra-molecular contacts are nucleic acids and proteins. Proteins fold via the formation of contacts of various natures, including hydrogen bonds, disulfide bonds, and beta-beta interactions. RNA molecules fold by forming hydrogen bonds between nucleotides, forming nested or non-nested structures. Contacts in the genome are established via protein bridges including CTCF and cohesins and are measured by technologies including Hi-C. Circuit topology categorises the topological arrangement of these physical contacts, that are referred to as hard contacts (or h-contacts). Furthermore, chains can fold via knotting (or the formation of "soft" contacts (s-contacts)). Circuit topology uses a similar language to categorise both "soft" and "hard" contacts, and provides a full description of a folded linear chain. In this framework, a "circuit" refers to a segment of the chain where each contact site within the segment forms connections with other contact sites within the same segment, and thus is not left unpaired. A folded chain can thus be studied based on its constituting circuits. A simple example of a folded chain is a chain with two hard contacts. For a chain with two binary contacts, three arrangements are available: parallel (P), series (S), and crossed (X). For a chain with n contacts, the topology can be described by an n by n matrix in which each element illustrates the relation between a pair of contacts and may take one of the three states, P, S and X. Multivalent contacts can also be categorised in full or via decomposition into several binary contacts. Similarly, circuit topology allows for the classification of the pairwise arrangements of chain crossings and tangles, thus providing a complete 3D description of folded chains. Furthermore, one can apply circuit
|
{
"page_id": 43717327,
"source": null,
"title": "Circuit topology"
}
|
topology operations to soft and hard contacts to generate complex folds, using a bottom-up engineering approach. Both knot theory and circuit topology aim to describe chain entanglement, making it important to understand their relationship. Knot theory considers any entangled chain as a connected sum of prime knots, which are themselves undecomposable. Circuit topology splits any entangled chains (including prime knots) into basic structural units called soft contacts, and lists simple rules on how soft contacts can be put together. An advantage of circuit topology is that it can be applied to open linear chains with intra-chain interactions, so-called hard contacts. This enabled topological analysis of proteins and genomes, which are often described as "unknot" in knot theory. Finally, circuit topology enables studying interactions between hard contacts and entanglements and can identify slip knots, while knot theory typically overlooks hard contacts and split knots. Thus, circuit topology serves as a complementary approach to knot theory. Circuit topology has implications for folding kinetics and molecular evolution and has been applied to engineer polymers including molecular origami. Circuit topology along with contact order and size are determinants of the folding rate of linear polymers. The approach can also be used for medical applications including the prediction of pathogenicity of mutations. == Further reading == Scalvini, Barbara; Sheikhhassani, Vahid; Mashaghi, Alireza (2021). "Topological principles of protein folding". Physical Chemistry Chemical Physics. 23 (37): 21316–21328. Bibcode:2021PCCP...2321316S. doi:10.1039/D1CP03390E. hdl:1887/3277889. PMID 34545868. S2CID 237583577. Golovnev, Anatoly; Mashaghi, Alireza (September 2020). "Generalized Circuit Topology of Folded Linear Chains". iScience. 23 (9): 101492. Bibcode:2020iSci...23j1492G. doi:10.1016/j.isci.2020.101492. PMC 7481252. PMID 32896769. Heidari, Maziar; Schiessel, Helmut; Mashaghi, Alireza (24 June 2020). "Circuit Topology Analysis of Polymer Folding Reactions". ACS Central Science. 6 (6): 839–847. doi:10.1021/acscentsci.0c00308. PMC 7318069. PMID 32607431. == References == == See also == Molecular topology
|
{
"page_id": 43717327,
"source": null,
"title": "Circuit topology"
}
|
The biosphere (from Ancient Greek βίος (bíos) 'life' and σφαῖρα (sphaîra) 'sphere'), also called the ecosphere (from Ancient Greek οἶκος (oîkos) 'settlement, house' and σφαῖρα (sphaîra) 'sphere'), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to matter, with minimal inputs and outputs. Regarding energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 100 terawatts. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis (life created naturally from non-living matter, such as simple organic compounds) or biogenesis (life created from living matter), at least some 3.5 billion years ago. In a general sense, biospheres are any closed, self-regulating systems containing ecosystems. This includes artificial biospheres such as Biosphere 2 and BIOS-3, and potentially ones on other planets or moons. == Origin and use of the term == The term "biosphere" was coined in 1875 by geologist Eduard Suess, who defined it as the place on Earth's surface where life dwells. While the concept has a geological origin, it is an indication of the effect of both Charles Darwin and Matthew F. Maury on the Earth sciences. The biosphere's ecological context comes from the 1920s (see Vladimir I. Vernadsky), preceding the 1935 introduction of the term "ecosystem" by Sir Arthur Tansley (see ecology history). Vernadsky defined ecology as the science of the biosphere. It is an interdisciplinary concept for integrating astronomy, geophysics, meteorology, biogeography, evolution, geology, geochemistry, hydrology and, generally speaking, all
|
{
"page_id": 4816,
"source": null,
"title": "Biosphere"
}
|
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