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Topic Review
US Airways Livery
US Airways' aircraft livery has varied both under the US Airways and USAir name. In general the Express and Shuttle divisions have had liveries that closely parallel the company-wide livery at the time. The US Airways livery has been replaced with the new American Airlines livery, in accordance with their merger.
  • 5.8K
  • 16 Nov 2022
Topic Review
Biochemistry of Hydrogen Peroxide
Hydrogen Peroxide (H2O2) is the nonionized 2-electron reduction product of unstable molecular oxygen (O2), which plays a central role in maintaining the redox cycle of living cells.
  • 5.8K
  • 10 Jan 2022
Topic Review
Holobiont
A holobiont is an assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit, though there is controversy over this discreteness. The components of a holobiont are individual species or bionts, while the combined genome of all bionts is the hologenome. The concept of the holobiont was initially defined by Dr. Lynn Margulis in her 1991 book Symbiosis as a Source of Evolutionary Innovation, though the concept has subsequently evolved since the original definition. Holobionts include the host, virome, microbiome, and other members, all of which contribute in some way to the function of the whole. Well-studied holobionts include reef-building corals and humans.
  • 5.7K
  • 14 Oct 2022
Topic Review
Fluid Catalytic Cracking Catalyst Regeneration Intensification Technologies
Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator component plays a critical role in optimizing the overall profitability by efficiently restoring the catalyst activity and enhancing the heat balance in the riser reactor. Improvement in the device metallurgy and process operations have enabled industrial regenerators to operate at high temperatures with a better coke burning rate and longer operating cycle. Today, the carbon content of regenerated catalyst has drastically reduced to less than 0.1 wt.%.
  • 5.8K
  • 15 Mar 2022
Topic Review
Types of Transcatheter Aortic Valve Replacement Devices
Transcatheter aortic valve replacement (TAVR) was originally conceptualized in the early 1990s, largely inspired by the pioneering experiences in the field of percutaneous transluminal coronary angioplasty.
  • 5.8K
  • 03 Aug 2022
Topic Review Video
Risk Management in Information Systems
Businesses are bombarded with great deals of risks, vulnerabilities, and unforeseen business interruptions in their lifetime, which negatively affect their productivity and sustainability within the market. Such risks require a risk management system to identify risks and risk factors and propose approaches to eliminate or reduce them. Risk management involves highly structured practices that should be implemented within an organization, including organizational planning documents. Continuity planning and fraud detection policy development are among the many critically important practices conducted through risk management that aim to mitigate risk factors, their vulnerability, and their impact. Information systems play a pivotal role in any organization by providing many benefits, such as reducing human errors and associated risks owing to the employment of sophisticated algorithms. Both the development and establishment of an information system within an organization contributes to mitigating business-related risks and also creates new types of risks associated with its establishment. Businesses must prepare for, react to, and recover from unprecedented threats that might emerge in the years or decades that follow.
  • 5.7K
  • 15 Dec 2021
Topic Review
Libertarian Marxism
Libertarian Marxism is a broad scope of economic and political philosophies that emphasize the anti-authoritarian and libertarian aspects of Marxism. Early currents of libertarian Marxism such as left communism emerged in opposition to Marxism–Leninism. Libertarian Marxism is often critical of reformist positions such as those held by social democrats. Libertarian Marxist currents often draw from Karl Marx and Friedrich Engels' later works, specifically the Grundrisse and The Civil War in France; emphasizing the Marxist belief in the ability of the working class to forge its own destiny without the need for a vanguard party to mediate or aid its liberation. Along with anarchism, libertarian Marxism is one of the main currents of libertarian socialism. Libertarian Marxism includes currents such as autonomism, council communism, De Leonism, Lettrism, parts of the New Left, Situationism, Socialisme ou Barbarie and workerism. Libertarian Marxism has often had a strong influence on both post-left and social anarchists. Notable theorists of libertarian Marxism have included Maurice Brinton, Cornelius Castoriadis, Guy Debord, Raya Dunayevskaya, Daniel Guérin, C. L. R. James, Rosa Luxemburg, Antonio Negri, Anton Pannekoek, Fredy Perlman, Ernesto Screpanti, E. P. Thompson, Raoul Vaneigem and Yanis Varoufakis, who claims that Marx himself was a libertarian Marxist.
  • 5.7K
  • 11 Nov 2022
Topic Review
Force Field
In the context of chemistry and molecular modelling, a force field is a computational method that is used to estimate the forces between atoms within molecules and also between molecules. More precisely, the force field refers to the functional form and parameter sets used to calculate the potential energy of a system of atoms or coarse-grained particles in molecular mechanics, molecular dynamics, or Monte Carlo simulations. The parameters for a chosen energy function may be derived from experiments in physics and chemistry, calculations in quantum mechanics, or both. Force fields are interatomic potentials and utilize the same concept as force fields in classical physics, with the difference that the force field parameters in chemistry describe the energy landscape, from which the acting forces on every particle are derived as a gradient of the potential energy with respect to the particle coordinates. All-atom force fields provide parameters for every type of atom in a system, including hydrogen, while united-atom interatomic potentials treat the hydrogen and carbon atoms in methyl groups and methylene bridges as one interaction center. Coarse-grained potentials, which are often used in long-time simulations of macromolecules such as proteins, nucleic acids, and multi-component complexes, sacrifice chemical details for higher computing efficiency.
  • 5.7K
  • 10 Nov 2022
Topic Review
Gravity Well
A gravity well or gravitational well is a conceptual model of the gravitational field surrounding a body in space – the more massive the body, the deeper and more extensive the gravity well associated with it. The Sun is very massive, relative to other bodies in the Solar System, so the corresponding gravity well that surrounds it appears "deep" and far-reaching. The gravity wells of asteroids and small moons, conversely, are often depicted as very shallow. Anything at the center of mass of a planet or moon is considered to be at the bottom of that celestial body's gravity well, and so escaping the effects of gravity from such a planet or moon (to enter outer space) can be likened to "climbing out of the gravity well". The deeper a gravity well is, the more energy any space-bound "climber" must use to escape it. In astrophysics, a gravity well is specifically the gravitational potential field around a massive body. Other types of potential wells include electrical and magnetic potential wells. Physical models of gravity wells are sometimes used to illustrate orbital mechanics. Gravity wells are frequently confused with embedding diagrams used in general relativity theory, but the two concepts are distinctly separate and not directly related.
  • 5.7K
  • 12 Oct 2022
Topic Review
Vitamin D Synthesis and Metabolism
Vitamin D, conventionally considered a nutrient, is a potent hormone regulating many physiological functions. Vitamin D exists as a prohormone that needs to be transformed into biologically active products that bind to their cognate nuclear receptors to regulate diverse physiological processes.
  • 5.7K
  • 13 Apr 2022
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