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Proportional Representation
Proportional representation (PR) characterizes electoral systems in which divisions in an electorate are reflected proportionately in the elected body. The concept applies mainly to geographical and political divisions of the electorate. The essence of such systems is that all votes contribute to the result—not just a plurality, or a bare majority. The most prevalent forms of proportional representation all require the use of multiple-member voting districts (also called super-districts), as it is not possible to fill a single seat in a proportional manner. In fact, PR systems that achieve the highest levels of proportionality tend to include districts with large numbers of seats, as large as a province or an entire nation. The most widely used families of PR electoral systems are party-list PR, single transferable vote (STV), and mixed-member PR (MMP). In the European Parliament for instance, each member state has a number of seats that is (roughly) proportional to its population, enabling geographical proportional representation. Almost all European countries also have political proportional representation (ideological proportional representation to the degree that parties honestly describe their goals): When n% of the electorate support a particular political party or set of candidates as their favorite, then roughly n% of seats are allotted to that party or those candidates. According to the ACE Electoral Knowledge Network, some form of proportional representation is used for national lower house elections in 94 countries. Party list PR, being used in 85 countries, is the most widely used. MMP is used in seven lower houses. STV is used in only two: Ireland, since independence in 1922, and Malta, since 1921. STV is also used in the Australian Senate, and can be used for nonpartisan elections such as the city council of Cambridge MA. Due to factors such as electoral thresholds and the use of small constituencies, as well as manipulation tactics such as party splitting and gerrymandering, perfect proportionality is rarely achieved under these systems. Nonetheless, they approximate proportionality much better than other systems. Some jurisdictions use leveling seats to compensate for such factors.
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  • 14 Oct 2022
Topic Review
Organ
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system. An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that makes the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the connective tissues that provide a suitable place for it to be situated and anchored. The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Organs exist in most multicellular organisms. In single-celled organisms such as bacteria, the functional analogue of an organ is known as an organelle. In plants, there are three main organs. In the study of anatomy, viscera (singular viscus) refers to the internal organs of the abdominal, thoracic, and pelvic cavities. The abdominal organs may be classified as solid organs, or hollow organs. The solid organs are the liver, pancreas, spleen, kidneys, and adrenal glands. The hollow organs of the abdomen are the stomach, intestines, gallbladder, bladder, and rectum. In the thoracic cavity the heart is a hollow, muscular organ. The number of organs in any organism depends on the definition used. By one widely adopted definition, 79 organs have been identified in the human body.
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  • 14 Oct 2022
Topic Review
Six Thinking Hats
Six Thinking Hats was written by Dr. Edward de Bono. "Six Thinking Hats" and the associated idea parallel thinking provide a means for groups to plan thinking processes in a detailed and cohesive way, and in doing so to think together more effectively.
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  • 14 Oct 2022
Topic Review
Correlation and Dependence
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. In the broadest sense correlation is any statistical association, though it commonly refers to the degree to which a pair of variables are linearly related. Familiar examples of dependent phenomena include the correlation between the height of parents and their offspring, and the correlation between the price of a good and the quantity the consumers are willing to purchase, as it is depicted in the so-called demand curve. Correlations are useful because they can indicate a predictive relationship that can be exploited in practice. For example, an electrical utility may produce less power on a mild day based on the correlation between electricity demand and weather. In this example, there is a causal relationship, because extreme weather causes people to use more electricity for heating or cooling. However, in general, the presence of a correlation is not sufficient to infer the presence of a causal relationship (i.e., correlation does not imply causation). Formally, random variables are dependent if they do not satisfy a mathematical property of probabilistic independence. In informal parlance, correlation is synonymous with dependence. However, when used in a technical sense, correlation refers to any of several specific types of mathematical operations between the tested variables and their respective expected values. Essentially, correlation is the measure of how two or more variables are related to one another. There are several correlation coefficients, often denoted [math]\displaystyle{ \rho }[/math] or [math]\displaystyle{ r }[/math], measuring the degree of correlation. The most common of these is the Pearson correlation coefficient, which is sensitive only to a linear relationship between two variables (which may be present even when one variable is a nonlinear function of the other). Other correlation coefficients – such as Spearman's rank correlation – have been developed to be more robust than Pearson's, that is, more sensitive to nonlinear relationships. Mutual information can also be applied to measure dependence between two variables.
  • 8.5K
  • 14 Oct 2022
Topic Review
Minority Stress
Minority stress describes chronically high levels of stress faced by members of stigmatized minority groups. It may be caused by a number of factors, including poor social support and low socioeconomic status; well understood causes of minority stress are interpersonal prejudice and discrimination. Governmental discrimination typically takes form in constitutional discrimination and stays that way until equal protections are applied. Many of these have roots in scriptural discrimination. Indeed, numerous scientific studies have shown that minority individuals experience a high degree of prejudice, which causes stress responses (e.g., high blood pressure, anxiety) that accrue over time, eventually leading to poor mental and physical health. Minority stress theory summarizes these scientific studies to explain how difficult social situations lead to chronic stress and poor health among minority individuals. It is an important concept for psychologists and public health officials who seek to understand and reduce minority health disparities.
  • 2.5K
  • 18 Oct 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.
  • 8.9K
  • 14 Oct 2022
Topic Review
SENSOR-Pesticides
Sentinel Event Notification System for Occupational Risks (SENSOR)-Pesticides is a U.S. state-based surveillance program that monitors pesticide-related illness and injury. It is administered by the National Institute for Occupational Safety and Health (NIOSH), twelve state health agencies participate. NIOSH provides technical support to all participating states. It also provides funding to some states, in conjunction with the US Environmental Protection Agency (US EPA). Pesticide-related illness is a significant occupational health issue, but it is believed to be underreported. Because of this, NIOSH proposed the SENSOR program to track pesticide poisonings. Because workers in many industries are at risk for pesticide exposure, and public concern exists regarding the use of and exposure to pesticides, government and regulatory authorities experience pressure to monitor health effects associated with them. SENSOR-Pesticides state partners collect case data from several different sources using a standard case definition and set of variables. This information is then forwarded to the program headquarters at NIOSH where it is compiled and put into a national database. Researchers and government officials from the SENSOR-Pesticides program have published research articles that highlight findings from the data and their implications for environmental and occupational pesticide issues. These issues include eradication of invasive species, pesticide poisoning in schools, birth defects, and residential use of total release foggers, or "bug bombs," which are devices that release an insecticide mist.
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  • 14 Oct 2022
Topic Review
Alternating Direction Implicit Method
In numerical linear algebra, the Alternating Direction Implicit (ADI) method is an iterative method used to solve Sylvester matrix equations. It is a popular method for solving the large matrix equations that arise in systems theory and control, and can be formulated to construct solutions in a memory-efficient, factored form. It is also used to numerically solve parabolic and elliptic partial differential equations, and is a classic method used for modeling heat conduction and solving the diffusion equation in two or more dimensions. It is an example of an operator splitting method.
  • 6.0K
  • 14 Oct 2022
Topic Review
Greylisting
Greylisting is a method of defending e-mail users against spam. A mail transfer agent (MTA) using greylisting will "temporarily reject" any email from a sender it does not recognize. If the mail is legitimate, the originating server will try again after a delay, and if sufficient time has elapsed, the email will be accepted.
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  • 14 Oct 2022
Topic Review
Cybersecurity Standards
Cybersecurity standards (also styled cyber security standards) are techniques generally set forth in published materials that attempt to protect the cyber environment of a user or organization. This environment includes users themselves, networks, devices, all software, processes, information in storage or transit, applications, services, and systems that can be connected directly or indirectly to networks. The principal objective is to reduce the risks, including prevention or mitigation of cyber-attacks. These published materials consist of collections of tools, policies, security concepts, security safeguards, guidelines, risk management approaches, actions, training, best practices, assurance and technologies.
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  • 14 Oct 2022
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