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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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Absenteeism
Absenteeism is a habitual pattern of absence from a duty or obligation without good reason. Generally, absenteeism is unplanned absences. Absenteeism has been viewed as an indicator of poor individual performance, as well as a breach of an implicit contract between employee and employer. It is seen as a management problem, and framed in economic or quasi-economic terms. More recent scholarship seeks to understand absenteeism as an indicator of psychological, medical, or social adjustment to work.
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  • 23 Nov 2022
Topic Review
Pascal's Wager
Pascal's Wager is an argument in philosophy presented by the seventeenth-century French philosopher, mathematician and physicist Blaise Pascal (1623–62). It posits that humans bet with their lives that God either exists or does not. Pascal argues that a rational person should live as though God exists and seek to believe in God. If God does not actually exist, such a person will have only a finite loss (some pleasures, luxury, etc.), whereas he stands to receive infinite gains (as represented by eternity in Heaven) and avoid infinite losses (eternity in Hell). Pascal's Wager was based on the idea of the Christian God, though similar arguments have occurred in other religious traditions. The original wager was set out in section 233 of Pascal's posthumously published Pensées ("Thoughts"). These previously unpublished notes were assembled to form an incomplete treatise on Christian apologetics. Historically, Pascal's Wager was groundbreaking because it charted new territory in probability theory, marked the first formal use of decision theory, and anticipated future philosophies such as existentialism, pragmatism and voluntarism.
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  • 23 Nov 2022
Topic Review
Erysipelas
Erysipelas (/ˌɛrəˈsɪpələs/) is a relatively common bacterial infection of the superficial layer of the skin (upper dermis), extending to the superficial lymphatic vessels within the skin, characterized by a raised, well-defined, tender, bright red rash, typically on the face or legs, but which can occur anywhere on the skin. It is a form of cellulitis and is potentially serious. Erysipelas is usually caused by the bacteria Streptococcus pyogenes, also known as group A β-hemolytic streptococci, through a break in the skin such as from scratches or an insect bite. It is more superficial than cellulitis, and is typically more raised and demarcated. The term is from Greek ἐρυσίπελας (erysípelas), meaning "red skin". In animals, erysipelas is a disease caused by infection with the bacterium Erysipelothrix rhusiopathiae. The disease caused in animals is called Diamond Skin Disease, which occurs especially in pigs. Heart valves and skin are affected. Erysipelothrix rhusiopathiae can also infect humans, but in that case, the infection is known as erysipeloid.
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  • 23 Nov 2022
Topic Review
ACID (Computer Science)
In computer science, ACID (Atomicity, Consistency, Isolation, Durability) is a set of properties of database transactions intended to guarantee validity even in the event of errors, power failures, etc. In the context of databases, a sequence of database operations that satisfies the ACID properties (and these can be perceived as a single logical operation on the data) is called a transaction. For example, a transfer of funds from one bank account to another, even involving multiple changes such as debiting one account and crediting another, is a single transaction. In 1983, Andreas Reuter and Theo Härder coined the acronym ACID as shorthand for Atomicity, Consistency, Isolation, and Durability, building on earlier work by Jim Gray who enumerated Atomicity, Consistency, and Durability but left out Isolation when characterizing the transaction concept. These four properties describe the major guarantees of the transaction paradigm, which has influenced many aspects of development in database systems. According to Gray and Reuter, IMS supported ACID transactions as early as 1973 (although the term ACID came later).
  • 2.0K
  • 23 Nov 2022
Topic Review
Decimation (Signal Processing)
In digital signal processing, decimation is the process of reducing the sampling rate of a signal.  The term downsampling usually refers to one step of the process, but sometimes the terms are used interchangeably.  Complementary to upsampling, which increases sampling rate, decimation is a specific case of sample rate conversion in a multi-rate digital signal processing system. A system component that performs decimation is called a decimator. When decimation is performed on a sequence of samples of a signal or other continuous function, it produces an approximation of the sequence that would have been obtained by sampling the signal at a lower rate (or density, as in the case of a photograph). The decimation factor is usually an integer or a rational fraction greater than one. This factor multiplies the sampling interval or, equivalently, divides the sampling rate. For example, if compact disc audio at 44,100 samples/second is decimated by a factor of 5/4, the resulting sample rate is 35,280.
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  • 23 Nov 2022
Topic Review
Large UV Optical Infrared Surveyor
The Large UV Optical Infrared Surveyor (LUVOIR) is a multi-wavelength space observatory concept being developed by the Goddard Space Flight Center and proposed for the Decadal Survey Concept Study started in January 2016. The concept is based on a mirror from 8 m to 18 m in diameter, and covering the ultraviolet, visible and infrared wavelengths. It would be a Large Strategic Science Mission and be up for selection sometime after 2020. LUVOIR is a set of goals and requirements for a space telescope, but is not a specific design. More concrete proposals have their own names, such as ATLAST and HDST. One of those will be selected to become LUVOIR.
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  • 23 Nov 2022
Topic Review
Ground Deicing of Aircraft
Ground deicing of aircraft is commonly performed in both commercial and general aviation. The fluids used in this operation are called deicing or anti-icing fluids. The initials ADF (Aircraft Deicing Fluid), ADAF (Aircraft Deicer and Anti-icer Fluid) or AAF (Aircraft Anti-icing Fluid) are commonly used.
  • 1.5K
  • 23 Nov 2022
Topic Review
SIMD
Single instruction, multiple data (SIMD) is a type of parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (ISA): it should not be confused with an ISA. SIMD describes computers with multiple processing elements that perform the same operation on multiple data points simultaneously. Such machines exploit data level parallelism, but not concurrency: there are simultaneous (parallel) computations, but each unit performs the exact same instruction at any given moment (just with different data). SIMD is particularly applicable to common tasks such as adjusting the contrast in a digital image or adjusting the volume of digital audio. Most modern CPU designs include SIMD instructions to improve the performance of multimedia use. SIMD has three different subcategories in Flynn's 1972 Taxonomy, one of which is SIMT. SIMT should not be confused with software threads or hardware threads, both of which are task time-sharing (time-slicing). SIMT is true simultaneous parallel hardware-level execution.
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  • 23 Nov 2022
Topic Review
History of Fair Trade
The fair trade movement has undergone several important changes since its early days following World War II. Fair trade, first seen as a form of charity advocated by religious organizations, has radically changed in structure, philosophy and approach. The past fifty years have witnessed massive changes in the diversity of fair trade proponents, the products traded and their distribution networks.
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  • 23 Nov 2022
Topic Review
Wonders of the World
Various lists of the Wonders of the World have been compiled from antiquity to the present day, to catalogue the world's most spectacular natural wonders and manmade structures. The Seven Wonders of the Ancient World is the first known list of the most remarkable creations of classical antiquity; it was based on guidebooks popular among Ancient Greece sightseers and only includes works located around the Mediterranean rim and in Mesopotamia. The number seven was chosen because the Greeks believed it represented perfection and plenty, and because it was the number of the five planets known anciently, plus the sun and moon. Many similar lists have been made.
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  • 23 Nov 2022
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