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Dissociation constant

In chemistry and pharmacology, a dissociation constant is a specific type of equilibrium constant that measures the propensity of a larger object to separate reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into its component ions. The dissociation constant is the inverse of the association constant. In the special case of salts, the dissociation constant can be called an ionization constant. For a general reaction: A x B y ↽ − − ⇀ x A + y B in which a complex A x B y breaks down into x A subunits and y B subunits, the dissociation constant is defined K d = x y where, are the equilibrium concentrations of A, B, the complex AxBy, respectively. One reason for the popularity of the dissociation constant in biochemistry and pharmacology is that in the encountered case where x=y=1, Kd has a simple physical interpretation: when = K d, = or equivalently + = 1 2; that is, Kd, which has the dimensions of concentration, equals the concentration of free A at which half of the total molecules of B are associated with A.

This simple interpretation does not apply for higher values of y. It presumes the absence of competing reactions, though the derivation can be extended to explicitly allow for and describe competitive binding, it is useful as a quick description of the binding of a substance, in the same way that EC50 and IC50 describe the biological activities of substances. Experimentally, the concentration of the molecule complex is obtained indirectly from the measurement of the concentration of a free molecules, either or. In principle, the total amounts of molecule 0 and 0 added to the reaction are known, they separate into free and bound components according to the mass conservation principle: 0 = + 0 = + To track the concentration of the complex, one substitutes the concentration of the free molecules, of the respective conservation equations, by the definition of the dissociation constant, 0 = K d + This yields the concentration of the complex related to the concentration of either one of the free molecules = 0 K d + = 0 K d + Many biological proteins and enzymes can possess more than one binding site.

When a ligand L binds with a macromolecule M, it can influence binding kinetics of other ligands L binding to the macromolecule. A simplified mechanism can be formulated if the affinity of all binding sites can be considered independent of the number of ligands bound to the macromolecule; this is valid for macromolecules composed of more than one identical, subunits. It can be assumed that each of these n subunits are identical and that they possess only one single binding site; the concentration of bound ligands bound {\displaystyle {{\ce {

Mohammed bin Hashim al-Awadhy

Mohammed bin Hashim al-Awadhy was a Qatari militant and the coordinator and promoter of the "Wa Atasemo for the Relief of Our People in Syria" Islamic charity organization. Mohammed was the son of a Qatari businessman. Mohammed was killed in battle in northeastern Syria in early 2015, it is believed that he was fighting with Ahrar al-Sham at the time, although ISIS supporters have labeled al-Awadhy as a "martyr." Mohammed al-Awadhy was the son of Hashim al-Awadhy, Hashim al-Awadhy is the owner of Rabia TV, a media outlet in support of the Muslim Brotherhood, serves as the Director of the Media Center at Eid Charity, an organization with ties to Hamas and founded by Specially Designated Global Terrorist al-Nuaymi. "Wa Atasemo for the Relief of Our People in Syria" is a defunct Islamic charitable organization announced in 2013. Pictures on Wa Atasemo's social media accounts have shown the delivery of relief materials including blankets and wheelchairs to Syrians in need. Wa Atasemo has called for donations of 950 Qatari Riyals to support its missions.

In 2014, Mohammed al-Awadhi claimed that the charity had received donations from "kind people" in Qatar, Saudi Arabia, Kuwait and the UAE. Mohammed bin Hashim al-Awadhy's name and phone number is featured on the picture distributed on social media to promote the charity. In addition, al-Awadhy promoted the campaign from his personal social media accounts. On Twitter, the Wa Atasemo account only follows the account of Mohammed al-Awadhy. A large number of the accounts following Wa Atasemo's Twitter page are supporters of ISIS as well as other Salafist groups in Syria. Reports of Mohammed al-Awadhy's death surfaced in February 2014, it is reported that he was found dead in northern Syria on the path between Binnish and Taftanaz, two towns in the Idlib Governorate in northwestern Syria. Although al-Awadhy was referred to as a "Qatari recruit", it is unclear which group he was fighting for Syria. Multiple reports and social media posts have tied al-Awadhy to Ahrar al-Sham. However, al-Awadhy was described as member of the "convoy of martyrs" by media outlets that support ISIS and a former member of the "Raqqa Province," the headquarters of ISIS

Entertainment rigging

Rigging in entertainment can be broken down into two main subjects – theatrical rigging and arena style rigging. All the same skills apply in both genres; the first takes place in a theatre, involves the theatre's permanent fly system. The other in an arena or "exposed structure venue" such as a convention center, warehouse etc. Many arena riggers find themselves hanging a full proscenium theater in an arena environment. Circus rigging, comprising aerial acrobatic apparatuses that support human beings under dynamic loading conditions, stabilization rigging for large scale fabric tension structures, is under appreciated in the general rigging field, may be considered by some to be a separate field. However, the principles of physics and the standards of engineering that apply to theatrical and arena rigging still hold true in circus rigging, much of the same equipment and many of the same devices are used. All the same skills apply in this genre as well. Chain motors and trusses are not used as in tented circuses as in arena or theater rigging, however arena circuses make regular use of them.

In both tented and arena circuses, crane-bars or frames stabilized by guy cables, hung from fiber rope block and tackle systems are common, as are systems supporting and tensioning safety nets. High wire rigging, while simple in principle and application, requires substantial load-path capacity, as wire walkers require high tension in their systems. Automation rigging is used by many circuses, to prop elements. In theatrical rigging the venue may have anything from a dead pull scenery flying system, a hemp rigging system, a counterweight rigging system, a winch or hoist driven automated rigging system, or any hybrid of the aforementioned, used to fly props and scenery. Both of these rigging disciplines have four basic stations. Maintains safe perimeters underneath high work being done, maintains a safe path and perimeter around aerial work platforms, monitors the movement of aerial work platforms, assembles rigging on the ground for high work being done, attaches gear and assemblies to lines for high work being done, marks or "lays " out points on the floor and moves designators for high work and checks out motion control systems, makes attachments to lifting frames, lighting trusses, audio and scenery for hoisting or flying, does visual and mechanical safety inspections.

Has all of the skills and responsibility of a ground rigger and must be able to operate an aerial work platform, must be able to identify suitable structure and attachment for rigging, must be able to lift 100 lbs, must have advanced rope skills, be able to apply rope work mechanical advantages, as well as knowledge of materials, manufacturing methods and the proper applications of different rigging systems.. Is identical to a bucket rigger, only they apply their trade while standing, sitting on or hanging from an exposed structural member. Has all of the previous skills and responsibilities of the other 3 riggers and they must have exceptional rope skills, they must be physically fit and able to pull their own body weight up into structural ceilings on belay while applying personal fall protection as they go. They must be proficient with harness positioning systems and advanced rope friction and hauling systems. Most entertainment rigging training is done either by apprenticeship or formal training through unions i.e. IATSE.

In US, the recognized entertainment rigging certification is the E. T. C. P. Arena and theater rigging certification programs as well as S. P. R. A. T rope access training. In UK the PLASA NRC is the recognized entertainment rigging certification. Donovan, Harry. Entertainment Rigging. SAP

Phillips Payson

Phillips Payson was an American Congregationalist minister for the town of Walpole, Province of Massachusetts Bay. He is the ancestor of many distinguished clergymen of New England. Rev. Phillips Payson was born 29 February 1704 and baptized 12 March 1704 in Dorchester, Suffolk County, Province of Massachusetts Bay, the son of Rev. Samuel Payson and his wife Mary, the daughter of Elder Thomas Wiswall; the Payson family originated from Nazeing, first settling in the Massachusetts Bay Colony as early as 1635. The Reverend is not the same person as his first cousin Phillips Payson who died young, the son of his uncle Rev. Edward Payson and Elizabeth Phillips, he received an A. B. from Harvard College in 1724. He was an American Congregationalist minister in his home town of Dorchester from 1728, he competed for the position of senior minister, was one of three finalists at First Parish Church of Dorchester in 1729, but was not selected for ordination. Thereafter he was ordained the minister for the town of Walpole.

On 17 November 1733 in Walpole, Suffolk County, he married Anne Swift. The people of the town of Walpole were integral to the cause of liberty before and during the American Revolution. George Payson who served as a delegate of a Committee of Correspondence was one of his sons. By his wife Anne Swift, his children included: Phillips Payson aka Samuel Phillips Payson, H. C. 1754, D. D. Seth Payson, H. C. 1777, D. D., father of: Edward Payson, H. C. 1803, D. D. minister of Portland, Maine. In 1834, twenty-two of his name, says Farmer, had been graduates at Harvard and Dartmouth. Seven of the thirteen from Harvard were clergy. Rev. Phillips Payson is buried in the Rumney Marsh Burying Ground in Revere, Massachusetts

Rind et al. controversy

The Rind et al. controversy was a debate in the scientific literature, public media, government legislatures in the United States regarding a 1998 peer reviewed meta-analysis of the self-reported harm caused by child sexual abuse. The debate resulted in the unprecedented condemnation of the paper by both chambers of the United States Congress; the social science research community was concerned that the condemnation by government legislatures might have a chilling effect on the future publication of controversial research results. The study's lead author is psychologist Bruce Rind, it expanded on a 1997 meta-analysis for which Rind is lead author; the authors stated their goal was to determine whether CSA caused pervasive, significant psychological harm for both males and females, controversially concluding that the harm caused by child sexual abuse was not intense or pervasive, that the prevailing construct of CSA was not scientifically valid, as it failed empirical verification, that the psychological damage caused by the abusive encounters depends on other factors such as the degree of coercion or force involved.

The authors concluded that though CSA may not result in lifelong, significant harm to all victims, this does not mean it is not morally wrong and indicated that their findings did not imply current moral and legal prohibitions against CSA should be changed. The Rind et al. study has been criticized by many scientists and researchers, on the grounds that its methodology and conclusions are poorly designed and statistically flawed. Its definition of harm, for example, has been subject to debate because it only examined long-term psychological effects, harm can result in a number of ways, including short-term or medical harm, a likelihood of revictimization, the amount of time the victim spent attending therapy for the abuse. Numerous studies and professional clinical experience in the field of psychology, both before and after Rind et al.'s publications, have long borne out that children cannot consent to sexual activity and that child and adolescent sexual abuse cause harm. Anna Salter comments that Rind et al.'s results are "truly an outlier" compared to other meta-analyses.

The Rind paper has been quoted by people and organizations advocating age of consent reform, pedophile or pederasty groups in support of their efforts to change attitudes towards pedophilia and to decriminalize sexual activity between adults and minors, by defense attorneys who have used the study to minimize harm in child sexual abuse cases. In 1997, psychology professor Bruce Rind from Temple University and doctoral student Philip Tromovitch from the University of Pennsylvania published a literature review in The Journal of Sex Research of seven studies regarding adjustment problems of victims of child sexual abuse. To avoid the sampling bias that, they argued, existed in most studies of CSA, the 1997 study combined data from studies using only national samples of individuals expected to be more representative of the population of child sexual abuse victims; this study examined 10 independent samples designed to be nationally representative, based on data from more than 8,500 participants.

Four of the studies came from the United States, one each came from Great Britain and Spain. Based on the results, they concluded that the general consensus associating CSA with intense, pervasive harm and long-term maladjustment was incorrect; the following year, Rind and Robert Bauserman published a meta-analysis in the Psychological Bulletin of 59 studies with an aggregate sample size of 35,703 college students. In most of the 59 studies, CSA was defined by the authors based on moral criteria. Integrating the sometimes disparate and conflicting definitions, CSA was defined as "a sexual interaction involving either physical contact or no contact between either a child or adolescent and someone older, or between two peers who are children or adolescents when coercion is used." "Child" was sometimes defined, not biologically, but as underaged or as a minor under the legal age of consent. All these studies were included in the meta-analysis because many CSA researchers, as well as lay persons, view all types of socio-legally defined CSA as morally and/or psychologically harmful.

When this research, the U. S. Congress, the APA refer to CSA and "children" in the context of sexual relations with adults, they are not referring to biological children but to adolescents under the age of consent as well, which varies between 16 and 18 years old in the U. S; the results of the meta-analysis indicated that college students who had experienced CSA were less well-adjusted compared to other students who had not experienced CSA, but that family environment was a significant confound that may be responsible for the association between CSA and harm. Intense, pervasive harm and long-term maladjustment were due to confounding variables in most studies rather than to the sexual abuse itself. Both studies addressed four "assumed properties" of CSA, identified by the authors: gender equivalence, causality and intensity, concluding that all four "assumed properties" were questionab

Lists of trees

A listing of lists of trees. List of individual trees, including actual and mythical trees List of old growth forests List of superlative trees List of superlative trees in Sweden List of tree genera List of trees and shrubs by taxonomic family AfricaTrees of Africa List of Southern African indigenous trees and woody lianesAmericasTrees of Canada Trees of the Caribbean Basin Trees of North AmericaAsiaTrees of Iran Trees of PakistanAustralasiaTrees of Australia List of trees native to New ZealandEuropeList of trees of Denmark List of trees of Great Britain and Ireland List of indigenous trees and shrubs of Lithuania List of superlative trees in Sweden