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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Æternity
æternity is a public, open-source, blockchain-based distributed computing and digital-asset platform that builds upon decentralized cryptographic P2P technology. Real-world data can interface with smart contracts through "oracles". Scalability and trustless Turing-complete state channels set æternity apart from Blockchain 2.0 projects. æternity provides a virtual machine which can execute scripts implementing a so-called "smart contracts" using an decentralized global network of public nodes maintaining the blockchain. State channels enable smart contracts to remain private and scalable as long as there is no disagreement between the counterparties. Inherently integrated in æternity is a value token called an "æon" or "AE token", which can be transferred between participants and is used to compensate participant nodes for computations performed. AE tokens are used to pay for space and computation time on the virtual machine and prevent spam on the network while allocating storage and computation time proportionally to the incentive offered by the request.
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  • 18 Nov 2022
Biography
Anne Treisman
Anne Marie Treisman (née Taylor; 27 February 1935[1] – 9 February 2018)[2][3][4] was an English psychologist who specialised in cognitive psychology. Treisman researched visual attention, object perception, and memory. One of her most influential ideas is the feature integration theory of attention, first published with Garry Gelade in 1980. Treisman taught at the University of Oxford, Unive
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  • 18 Nov 2022
Topic Review
Electron Cloud Densitometry
Electron cloud densitometry is an interdisciplinary technology that uses the principles of quantum mechanics by the electron beam shifting effect. The effect is that the electron beam passing through the electron cloud, in accordance with the general principle of superposition of the system, changes its intensity in proportion to the probability density of the electron cloud. It gives direct visualization of the individual shapes of atoms, molecules and chemical bonds.
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  • 18 Nov 2022
Biography
Robert Stuart Jamieson
Robert Stuart (Stu) Jamieson (February 26, 1922 - September 23, 2006) was a musician, author, engineer, inventor, and patent agent. He was a dual-citizen of both Canada and the United States , and served in the 90th Chemical Mortar Battalion of the U.S. Army during the Second World War.[1] As a musician, he is credited with preserving Anglo-American, African-American, and Chinese folk music for
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  • 18 Nov 2022
Topic Review
Shellshock (Software Bug)
Shellshock, also known as Bashdoor, is a family of security bugs in the Unix Bash shell, the first of which was disclosed on 24 September 2014. Shellshock could enable an attacker to cause Bash to execute arbitrary commands and gain unauthorized access to many Internet-facing services, such as web servers, that use Bash to process requests. On 12 September 2014, Stéphane Chazelas informed Bash's maintainer Chet Ramey of his discovery of the original bug, which he called "Bashdoor". Working with security experts, Mr. Chazelas developed a patch (fix) for the issue, which by then had been assigned the vulnerability identifier CVE-2014-6271. The existence of the bug was announced to the public on 2014-09-24, when Bash updates with the fix were ready for distribution. The bug Chazelas discovered caused Bash to unintentionally execute commands when the commands are concatenated to the end of function definitions stored in the values of environment variables. Within days of its publication, a variety of related vulnerabilities were discovered (CVE-2014-6277, CVE-2014-6278, CVE-2014-7169, CVE-2014-7186 and CVE-2014-7187). Ramey addressed these with a series of further patches. Attackers exploited Shellshock within hours of the initial disclosure by creating botnets of compromised computers to perform distributed denial-of-service attacks and vulnerability scanning. Security companies recorded millions of attacks and probes related to the bug in the days following the disclosure. Because of the potential to compromise millions of unpatched systems, Shellshock was compared to the Heartbleed bug in its severity.
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  • 18 Nov 2022
Topic Review
Kikuchi Line
Kikuchi lines pair up to form bands in electron diffraction from single crystal specimens, there to serve as "roads in orientation-space" for microscopists not certain what they are looking at. In transmission electron microscopes, they are easily seen in diffraction from regions of the specimen thick enough for multiple scattering. Unlike diffraction spots, which blink on and off as one tilts the crystal, Kikuchi bands mark orientation space with well-defined intersections (called zones or poles) as well as paths connecting one intersection to the next. Experimental and theoretical maps of Kikuchi band geometry, as well as their direct-space analogs e.g. bend contours, electron channeling patterns, and fringe visibility maps are increasingly useful tools in electron microscopy of crystalline and nanocrystalline materials. Because each Kikuchi line is associated with Bragg diffraction from one side of a single set of lattice planes, these lines can be labeled with the same Miller or reciprocal-lattice indices that are used to identify individual diffraction spots. Kikuchi band intersections, or zones, on the other hand are indexed with direct-lattice indices i.e. indices which represent integer multiples of the lattice basis vectors a, b and c. Kikuchi lines are formed in diffraction patterns by diffusely scattered electrons, e.g. as a result of thermal atom vibrations. The main features of their geometry can be deduced from a simple elastic mechanism proposed in 1928 by Seishi Kikuchi, although the dynamical theory of diffuse inelastic scattering is needed to understand them quantitatively. In x-ray scattering these lines are referred to as Kossel lines (named after Walther Kossel).
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  • 18 Nov 2022
Topic Review
Lasersaur
Lasersaur is an open source laser cutter which was developed by NORTD Labs. Nortd Labs started shipping Lasersaur alpha kits in late 2010 after successful funding of the project in July 2010 on Kickstarter. Currently the project is funded via donations from their website or by purchasing part kits.
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  • 18 Nov 2022
Topic Review
Medical Underwriting
Medical underwriting is a health insurance term referring to the use of medical or health information in the evaluation of an applicant for coverage, typically for life or health insurance. As part of the underwriting process, an individual's health information may be used in making two decisions: whether to offer or deny coverage and what premium rate to set for the policy. The two most common methods of medical underwriting are known as moratorium underwriting, a relatively simple process, and full medical underwriting, a more indepth analysis of a client's health information. The use of medical underwriting may be restricted by law in certain insurance markets. If allowed, the criteria used should be objective, clearly related to the likely cost of providing coverage, practical to administer, consistent with applicable law, and designed to protect the long-term viability of the insurance system. It is the process in which an underwriter considers the health conditions of the person who is applying for the insurance, keeping in mind certain factors like health condition, age, nature of work, and geographical zone. After looking at all the factors, an underwriter suggests whether a policy should be given to the person and at what price, or premium.
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  • 18 Nov 2022
Topic Review
Chlamydiae
The Chlamydiae are a bacterial phylum and class whose members are remarkably diverse, including pathogens of humans and animals, symbionts of ubiquitous protozoa, and marine sediment forms not yet well understood. All of the Chlamydiae that humans have known about for many decades are obligate intracellular bacteria; in 2020 many additional Chlamydiae were discovered in ocean-floor environments, and it is not yet known whether they all have hosts. Historically it was believed that all Chlamydiae had a peptidoglycan-free cell wall, but studies in the 2010s demonstrated a detectable presence of peptidoglycan, as well as other important proteins. Among the Chlamydiae, all of the ones long known to science grow only by infecting eukaryotic host cells. They are as small as or smaller than many viruses. They are ovoid in shape and stain Gram-negative. They are dependent on replication inside the host cells; thus, some species are termed obligate intracellular pathogens and others are symbionts of ubiquitous protozoa. Most intracellular Chlamydiae are located in an inclusion body or vacuole. Outside cells, they survive only as an extracellular infectious form. These Chlamydiae can grow only where their host cells grow, and develop according to a characteristic biphasic developmental cycle. Therefore, clinically relevant Chlamydiae cannot be propagated in bacterial culture media in the clinical laboratory. They are most successfully isolated while still inside their host cells. Of various Chlamydiae that cause human disease, the two most important species are Chlamydia pneumoniae, which causes a type of pneumonia, and Chlamydia trachomatis, which causes chlamydia. Chlamydia is the most common bacterial sexually transmitted infection in the United States, and 2.86 million chlamydia infections are reported annually.
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  • 22 Nov 2022
Biography
Oscar Micheaux
Oscar Devereaux Micheaux (US: /mɪˈʃoʊ/ (listen); January 2, 1884 – March 25, 1951) was an African-American author, film director and independent producer of more than 44 films. Although the short-lived Lincoln Motion Picture Company was the first movie company owned and controlled by black filmmakers,[1] Micheaux is regarded as the first major African-American feature filmmaker, a prominen
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  • 18 Nov 2022
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