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Proton–Proton Chain
The proton–proton chain, also commonly referred to as the p-p chain, is one of two known sets of nuclear fusion reactions by which stars convert hydrogen to helium. It dominates in stars with masses less than or equal to that of the Sun, whereas the CNO cycle, the other known reaction, is suggested by theoretical models to dominate in stars with masses greater than about 1.3 times that of the Sun. In general, proton–proton fusion can occur only if the kinetic energy (i.e. temperature) of the protons is high enough to overcome their mutual electrostatic repulsion. In the Sun, deuterium-producing events are rare. Diprotons are the much more common result of proton–proton reactions within the star, and diprotons almost immediately decay back into two protons. Since the conversion of hydrogen to helium is slow, the complete conversion of the hydrogen initially in the core of the Sun is calculated to take more than ten billion years. Although sometimes called the "proton–proton chain reaction", it is not a chain reaction in the normal sense. In most nuclear reactions, a chain reaction designates a reaction that produces a product, such as neutrons given off during fission, that quickly induces another such reaction. The proton-proton chain is, like a decay chain, a series of reactions. The product of one reaction is the starting material of the next reaction. There are two main chains leading from Hydrogen to Helium in the Sun. One chain has five reactions, the other chain has six.
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  • 10 Nov 2022
Topic Review
Programmable System-on-Chip
PSoC (programmable system-on-chip) is a family of microcontroller integrated circuits by Cypress Semiconductor. These chips include a CPU core and mixed-signal arrays of configurable integrated analog and digital peripherals.
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Topic Review
Supply Chain Engineering
Supply Chain Engineering (SCE) describes desired efficiency and effectiveness. The most essential ingredient of SCE is its integral view embodying • Local Customization • Engineering • Information Technology The engineering character is not only visible in the SCE’s content but also in its name. As SCE is still a very young method only few standard works have been published so far; however, Kukkuk C, (Snr) in his opening address to the South African mining industry in 2015, sites "SEC should be regarded as an upstream practice and should not be a silo business unit, it may well be integrated with other key disciplines that form part of the 'value chain' some principles we apply are interactive sessions for front end planning, industry lessons learned, lean optimization strategies and updated ERP/MRP solutions" The following definition therefore mainly refers to the standard work, “Supply Chain Engineering – methods of integrated logistics planning”, published in July 2010 by Dr. Joachim Miebach and Dominik Bühring. Herein SCE is defined as an independent and overall method to design supply chains.
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Topic Review
First Universalist Church (Atlanta, Georgia)
The First Universalist Church of Atlanta, organized in 1895, re-established a Universalist presence in Atlanta, Georgia. Initial missionary efforts in 1879 were short-lived and failed to establish a permanent presence in the city. With the explicit assistance the Young People's Christian Union, this second missionary effort enabled the Universalists to sustain their presence and construct a church building on East Harris in 1900. The Universalists occupied the church until 1918 when they merged with Atlanta's Unitarians. The combined churches selected the Unitarian church on West Peachtree Street as their collective home. The combined church known by several names over the next three decades collapsed in 1951.
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Topic Review
Normal Gravity Formula
Normal gravity formulas are mathematical expressions, with which the free-fall acceleration at a point in vicinity to the surface of the earth can be estimated. Along with the mass (known or predicted) of a body, the weight is calculated.
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  • 10 Nov 2022
Topic Review
Hegemony
Hegemony (UK: /hɪˈɡɛməni, hɪˈdʒɛməni/, US: /hɪˈdʒɛməni/ (pronunciation (help·info)) or /ˈhɛdʒəˌmoʊni/) is the political, economic, or military predominance or control of one state over others. In Ancient Greece (8th century BC – 6th century AD), hegemony denoted the politico-military dominance of a city-state over other city-states. The dominant state is known as the hegemon. In the 19th century, hegemony came to denote the "Social or cultural predominance or ascendancy; predominance by one group within a society or milieu". Later, it could be used to mean "a group or regime which exerts undue influence within a society". Also, it could be used for the geopolitical and the cultural predominance of one country over others, from which was derived hegemonism, as in the idea that the Great Powers meant to establish European hegemony over Africa, Asia and Latin America. In cultural imperialism, the leader state dictates the internal politics and the societal character of the subordinate states that constitute the hegemonic sphere of influence, either by an internal, sponsored government or by an external, installed government. In international relations theory, hegemony denotes a situation of (i) great material asymmetry in favour of one state, that has (ii) enough military power to systematically defeat any potential contester in the system, (iii) controls the access to raw materials, natural resources, capital and markets, (iv) has competitive advantages in the production of value added goods, (v) generates an accepted ideology reflecting this status quo; and (vi) is functionally differentiated from other states in the system, being expected to provide certain public goods such as security, or commercial and financial stability. The Marxist theory of cultural hegemony, associated particularly with Antonio Gramsci, is the idea that the ruling class can manipulate the value system and mores of a society, so that their view becomes the world view (Weltanschauung): in Terry Eagleton's words, "Gramsci normally uses the word hegemony to mean the ways in which a governing power wins consent to its rule from those it subjugates". In contrast to authoritarian rule, cultural hegemony "is hegemonic only if those affected by it also consent to and struggle over its common sense".
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Topic Review
Deindividuation
Deindividuation is a concept in social psychology that is generally thought of as the loss of self-awareness in groups, although this is a matter of contention (resistance) (see below). Sociologists also study the phenomenon of deindividuation, but the level of analysis is somewhat different. For the social psychologist, the level of analysis is the individual in the context of a social situation. As such, social psychologists emphasize the role of internal psychological processes. Other social sciences, such as sociology, are more concerned with broad social, economic, political, and historical factors that influence events in a given society.
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Topic Review
Inner Core
The Earth's inner core is the Earth's innermost part. It is primarily a solid ball with a radius of about 1,220 kilometres (760 miles), which is about 70% of the Moon's radius. It is composed of an iron–nickel alloy and some other elements. The temperature at the inner core's surface is approximately 5,700 K (5,430 °C) or 9806 °F, which is about the temperature at the surface of the Sun.
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Topic Review
Parliamentary Train
A Parliamentary train is a passenger service operated in the United Kingdom to comply with the Railway Regulation Act 1844 that required train companies to provide inexpensive and basic rail transport for less affluent passengers. The act required that at least one such service per day be run on every railway route in the UK. Now no longer a legal requirement (although most franchise agreements require such trains), the term describes train services that continue to be run to avoid the cost of formal closure of a route or station but with reduced services often to just one train per week and without specially low prices. Such services are often called "ghost trains".
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Topic Review
Louvain Modularity
The Louvain Method for community detection is a method to extract communities from large networks created by Blondel et al. from the University of Louvain (affiliation of authors has given the method its name). The method is a greedy optimization method that appears to run in time [math]\displaystyle{ O(n \log n) }[/math].
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