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Hexadehydro Diels-Alder Reaction
In organic chemistry, the hexadehydro-Diels-Alder (HDDA) reaction is an organic chemical reaction between a diyne (2 alkyne functional groups arranged in a conjugated system) and an alkyne to form a reactive benzyne species, via a [4+2] cycloaddition reaction. This benzyne intermediate then reacts with a suitable trapping agent to form a substituted aromatic product. This reaction is a derivative of the established Diels-Alder reaction and proceeds via a similar [4+2] cycloaddition mechanism. The HDDA reaction is particularly effective for forming heavily functionalized aromatic systems and multiple ring systems in one synthetic step.
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  • 18 Oct 2022
Topic Review
Commutation Theorem
In mathematics, a commutation theorem explicitly identifies the commutant of a specific von Neumann algebra acting on a Hilbert space in the presence of a trace. The first such result was proved by Francis Joseph Murray and John von Neumann in the 1930s and applies to the von Neumann algebra generated by a discrete group or by the dynamical system associated with a measurable transformation preserving a probability measure. Another important application is in the theory of unitary representations of unimodular locally compact groups, where the theory has been applied to the regular representation and other closely related representations. In particular this framework led to an abstract version of the Plancherel theorem for unimodular locally compact groups due to Irving Segal and Forrest Stinespring and an abstract Plancherel theorem for spherical functions associated with a Gelfand pair due to Roger Godement. Their work was put in final form in the 1950s by Jacques Dixmier as part of the theory of Hilbert algebras. It was not until the late 1960s, prompted partly by results in algebraic quantum field theory and quantum statistical mechanics due to the school of Rudolf Haag, that the more general non-tracial Tomita–Takesaki theory was developed, heralding a new era in the theory of von Neumann algebras.
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  • 18 Oct 2022
Topic Review
AMD Radeon Rx 200 Series
The AMD Radeon R5/R7/R9 200 series is a family of GPUs developed by AMD. These GPUs are manufactured on a 28 nm Gate-Last process through TSMC or Common Platform Alliance.
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  • 18 Oct 2022
Topic Review
Neohumanism
Neohumanism is a holistic philosophical theory proposed by the Indian spiritual teacher Prabhat Ranjan Sarkar (1921 – 1990) to promote individual and collective progress. In this philosophy universalism plays a central role. It claims to elevate humanism to level of universalism. It claims not to have any grouping intention.
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  • 18 Oct 2022
Topic Review
Res Publica Christiana
In medieval and early modern Western political thought, the respublica or res publica Christiana refers to the international community of Christian peoples and states. As a Latin phrase, res publica Christiana combines Christianity with the originally Roman idea of the res publica ("republic" or "commonwealth") to describe this community and its well-being. A single English word with somewhat comparable meaning is Christendom; it is also translated as "the Christian Commonwealth".
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  • 18 Oct 2022
Topic Review
Intel C++ Compiler
Intel oneAPI DPC++/C++ Compiler and Intel C++ Compiler Classic are Intel’s C, C++, SYCL, and Data Parallel C++ (DPC++) compilers for Intel processor-based systems, available for Windows, Linux, and macOS operating systems.
  • 2.3K
  • 18 Oct 2022
Topic Review
X-ray Absorption Near Edge Structure
X-ray absorption near edge structure (XANES), also known as near edge X-ray absorption fine structure (NEXAFS), is a type of absorption spectroscopy that indicates the features in the X-ray absorption spectra (XAS) of condensed matter due to the photoabsorption cross section for electronic transitions from an atomic core level to final states in the energy region of 50–100 eV above the selected atomic core level ionization energy, where the wavelength of the photoelectron is larger than the interatomic distance between the absorbing atom and its first neighbour atoms.
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  • 18 Oct 2022
Topic Review
Relational Approach to Quantum Physics
The relational approach to quantum physics is an alternative approach to and interpretation of quantum mechanics. It asserts that the physical world can only be studied accurately in terms of relationships between systems, as all experimentally verifiable facts about the world result explicitly from interactions (such as the interaction between a light field and a detector). According to the relational approach, the assumption that objects possess absolute properties (such as an absolute particle, independent of any detection frame) inevitably leads to ambiguities and paradoxes when these objects are studied closely. The approach was adopted, in a time span of 1992-1996, by Q. Zheng, S. Hughes, and T. Kobayashi in the University of Tokyo. As early as in 1985, S. Kochen suggested that the paradoxes of quantum physics could be overcome by developing a relational approach, which was needed at one time to solve the paradoxes of relativistic physics of space and time. It is also hoped that this entry will serve as a complement to Rovelli’s relational quantum mechanics (RQM). Historically, the theory of relativity and quantum mechanics were intertwined with each other and the compatibility between both theories was a main theme throughout the Bohr-Einstein debate. In both theories the physicists emphasized that only measurable quantities, that is, observables, belong in a theory. Bohr compared his approach to Einstein’s theory of relativity and asserted that in the treatment of quantum processes the complementarity of the measuring results cannot be ignored, just as in high-speed phenomena the relativity of observation cannot be neglected when the simultaneity comes into question. But Einstein replied: “A good joke should not be repeated too often.” The debate continued in connection with Einstein-Podolsky-Rosen (EPR) paradox, and Bohr proposed the relational conception of quantum states. Through their analysis Bohm and Schumacher concluded that the characteristic feature of this debate is the failure to communicate due to the absence of a full harmony of quantum mechanics with relativity. Modern attempts to embrace a relational approach with interpretations of quantum mechanics have been tried many times, ranging from Everett's relative-state interpretation (Everett, 1957), sigma algebra of interactive properties (Kochen, 1979), quantum reference systems (Bene, 1992), quantum theory of the universe (Smolin, 1995), to relational quantum mechanics (Rovelli, 1996). They more or less emphasize the relational nature of quantum states. For more information, please refer to the further reading list.
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  • 21 Oct 2022
Topic Review
Zoom
Zoom Meetings (commonly shortened to Zoom, and stylized as zoom) is a proprietary videotelephony software program developed by Zoom Video Communications. The free plan allows up to 100 concurrent participants, with a 40-minute time restriction. Users have the option to upgrade by subscribing to a paid plan. The highest plan supports up to 1,000 concurrent participants for meetings lasting up to 30 hours. During the COVID-19 pandemic, there was a major increase in the use of Zoom for remote work, distance education, and online social relations. The increase led to Zoom being one of the most downloaded mobile app worldwide in 2020 with over 500 million downloads. In 2020 Zoom had over 300 million daily meeting participants.
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  • 18 Oct 2022
Topic Review
Transfusion Associated Circulatory Overload
In transfusion medicine, transfusion associated circulatory overload (aka TACO) is a transfusion reaction (an adverse effect of blood transfusion) resulting in signs or symptoms of excess fluid in the circulatory system (hypervolemia) within 12 hours after transfusion. The symptoms of TACO can include shortness of breath (dyspnea), low blood oxygen levels (hypoxemia), leg swelling (peripheral edema), high blood pressure (hypertension), and a high heart rate (tachycardia). It can occur due to a rapid transfusion of a large volume of blood but can also occur during a single red blood cell transfusion (about 15% of cases). It is often confused with transfusion-related acute lung injury (TRALI), another transfusion reaction. The difference between TACO and TRALI is that TRALI only results in symptoms of respiratory distress while TACO can present with either signs of respiratory distress, peripheral leg swelling, or both. Risk factors for TACO are diseases that increase the amount of fluid a person has, including liver, heart, or kidney failure, as well as conditions that require many transfusions. High and low extremes of age are a risk factor as well. The management of TACO includes immediate discontinuation of the transfusion, supplemental oxygen if needed, and medication to remove excess fluid.
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  • 18 Oct 2022
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