title: Hypersensitivity

text: Type II hypersensitivity reaction refers to an antibody-mediated immune reaction in which antibodies (IgG or IgM) are directed against cellular or extracellular matrix antigens with the resultant cellular destruction, functional loss, or damage to tissues.


title: Hypersensitivity

text: The pathophysiology of type II hypersensitivity reactions can be broadly classified into three types:


title: Hypersensitivity

text: In type III hypersensitivity reaction, an abnormal immune response is mediated by the formation of antigen-antibody aggregates called "immune complexes". They can precipitate in various tissues such as skin, joints, vessels, or glomeruli, and trigger the classical complement pathway. Complement activation leads to the recruitment of inflammatory cells (monocytes and neutrophils) that release lysosomal enzymes and free radicals at the site of immune complexes, causing tissue damage.


title: Hypersensitivity

text: The most common diseases involving a type III hypersensitivity reaction are serum sickness, post-streptococcal glomerulonephritis, systemic lupus erythematosus, farmers' lung (hypersensitivity pneumonitis), and rheumatoid arthritis.


title: Hypersensitivity

text: The principal feature that separates type III reactions from other hypersensitivity reactions is that in type III reaction, the antigen-antibody complexes are pre-formed in the circulation before their deposition in tissues.


title: Hypersensitivity

text: Type IV hypersensitivity reactions are, to some extent, normal physiological events that help fight infections, and dysfunction in this system can predispose to multiple opportunistic infections. Adverse events can also occur due to these reactions when an undesirable interaction between the immune system and an allergen happens.


title: Hypersensitivity

text: A Type IV hypersensitivity reaction is mediated by T cells that provoke an inflammatory reaction against exogenous or endogenous antigens. In certain situations, other cells, such as monocytes, eosinophils, and neutrophils, can be involved. After antigen exposure, an initial local immune and inflammatory response occurs that attracts leukocytes. The antigen engulfed by the macrophages and monocytes is presented to T cells, which then becomes sensitized and activated. These cells then release cytokines and chemokines, which can cause tissue damage and may result in illnesses.


title: Hypersensitivity

text: Examples of illnesses resulting from type IV hypersensitivity reactions include contact dermatitis and drug hypersensitivity. Type IV reactions are further subdivided into type IVa, IVb, IVc, and IVd based on the type of T cell (Th1, Th17 and CTLs) involved and the cytokines/chemokines produced.


title: Hypersensitivity

text: Delayed hypersensitivity plays a crucial role in our body's ability to fight various intracellular pathogens such as mycobacteria and fungi. They also play a principal role in tumor immunity and transplant rejection. Since patients with acquired immunodeficiency syndrome (AIDS) have a progressive decline in the number of CD4 cells, they also have a defective type four hypersensitivity reaction.


title: Hypersensitivity

text: The treatment of immediate hypersensitivity reactions includes the management of anaphylaxis with intramuscular adrenaline (epinephrine), oxygen, intravenous (IV) antihistamine, support blood pressure with IV fluids, avoid latex gloves and equipment in patients who are allergic, and surgical procedures such as tracheotomy if there is severe laryngeal edema.


title: A/B testing

text: A/B testing (also known as bucket testing, split-run testing, or split testing) is a user experience research methodology. A/B tests consist of a randomized experiment that usually involves two variants (A and B), although the concept can be also extended to multiple variants of the same variable. It includes application of statistical hypothesis testing or "two-sample hypothesis testing" as used in the field of statistics. A/B testing is a way to compare multiple versions of a single variable, for example by testing a subject's response to variant A against variant B, and determining which of the variants is more effective.


title: A/B testing

text: "A/B testing" is a shorthand for a simple randomized controlled experiment, in which a number of samples (e.g. A and B) of a single vector-variable are compared. These values are similar except for one variation which might affect a user's behavior. A/B tests are widely considered the simplest form of controlled experiment, especially when they only involve two variants. However, by adding more variants to the test, its complexity grows.


title: A/B testing

text: A/B tests are useful for understanding user engagement and satisfaction of online features like a new feature or product. Large social media sites like LinkedIn, Facebook, and Instagram use A/B testing to make user experiences more successful and as a way to streamline their services.


title: A/B testing

text: Today, A/B tests are being used also for conducting complex experiments on subjects such as network effects when users are offline, how online services affect user actions, and how users influence one another. A/B testing is used by data engineers, marketers, designers, software engineers, and entrepreneurs, among others. Many positions rely on the data from A/B tests, as they allow companies to understand growth, increase revenue, and optimize customer satisfaction.


title: A/B testing

text: Version A might be a version used at present (thus forming the control group), while version B is modified in some respect vs. A (thus forming the treatment group). For instance, on an e-commerce website the purchase funnel is typically a good candidate for A/B testing, since even marginal-decreases in drop-off rates can represent a significant gain in sales. Significant improvements can be sometimes seen through testing elements like copy text, layouts, images and colors, but not always. In these tests, users only see one of two versions, since the goal is to discover which of the two versions is preferable.


title: A/B testing

text: Multivariate testing or multinomial testing is similar to A/B testing, but may test more than two versions at the same time or use more controls. Simple A/B tests are not valid for observational, quasi-experimental or other non-experimental situations - commonplace with survey data, offline data, and other, more complex phenomena.


title: A/B testing

text: A/B testing is claimed by some to be a change in philosophy and business-strategy in certain niches, though the approach is identical to a between-subjects design, which is commonly used in a variety of research traditions. A/B testing as a philosophy of web development brings the field into line with a broader movement toward evidence-based practice. The benefits of A/B testing are considered to be that it can be performed continuously on almost anything, especially since most marketing automation software now typically comes with the ability to run A/B tests on an ongoing basis.


title: A/B testing

text: "Two-sample hypothesis tests" are appropriate for comparing the two samples where the samples are divided by the two control cases in the experiment. Z-tests are appropriate for comparing means under stringent conditions regarding normality and a known standard deviation. Student's t-tests are appropriate for comparing means under relaxed conditions when less is assumed. Welch's t test assumes the least and is therefore the most commonly used test in a two-sample hypothesis test where the mean of a metric is to be optimized. While the mean of the variable to be optimized is the most common choice of estimator, others are regularly used.


title: A/B testing

text: For a comparison of two binomial distributions such as a click-through rate one would use Fisher's exact test.


title: A/B testing

text: When conducting A/B testing, the user should evaluate the pros and cons of it to see if it aligns best with the results that they’re hoping for.


title: A/B testing

text: Pros: Through A/B testing, it’s easy to get a clear idea of what users prefer, since it’s directly testing one thing over the other. It’s based on real user behavior so the data can be very helpful especially when determining what works better between two options. In addition, it can also provide answers to very specific design questions. One example of this is Google's A/B testing with hyperlink colors. In order to optimize revenue, they tested dozens of different hyperlink hues to see which color the users tend to click more on.


title: A/B testing

text: Cons: However, there are a couple of cons to A/B testing. Like mentioned above, A/B testing is good for specific design questions but it can also be a downside since it’s mostly only good for specific design problems with very measurable outcomes. It could also be a very costly and timely process. Depending on the size of the company and/or team, there could be a lot of meetings and discussions about what exactly to test and what the impact of the A/B test is. If there’s not a significant impact, it could end up as a waste of time and resources.


title: A/B testing

text: In December 2018, representatives with experience in large-scale A/B testing from thirteen different organizations (Airbnb, Amazon, Booking.com, Facebook, Google, LinkedIn, Lyft, Microsoft, Netflix, Twitter, Uber, and Stanford University) attended a summit and summarized the top challenges in a SIGKDD Explorations paper.


title: A/B testing

text: The challenges can be grouped into four areas: Analysis, Engineering and Culture, Deviations from Traditional A/B tests, and Data quality.


title: A/B testing

text: It is difficult to definitively establish when A/B testing was first used. The first randomized double-blind trial, to assess the effectiveness of a homeopathic drug, occurred in 1835. Experimentation with advertising campaigns, which has been compared to modern A/B testing, began in the early twentieth century. The advertising pioneer Claude Hopkins used promotional coupons to test the effectiveness of his campaigns. However, this process, which Hopkins described in his Scientific Advertising, did not incorporate concepts such as statistical significance and the null hypothesis, which are used in statistical hypothesis testing. Modern statistical methods for assessing the significance of sample data were developed separately in the same period. This work was done in 1908 by William Sealy Gosset when he altered the Z-test to create Student's t-test.


title: A/B testing

text: With the growth of the internet, new ways to sample populations have become available. Google engineers ran their first A/B test in the year 2000 in an attempt to determine what the optimum number of results to display on its search engine results page would be. The first test was unsuccessful due to glitches that resulted from slow loading times. Later A/B testing research would be more advanced, but the foundation and underlying principles generally remain the same, and in 2011, 11 years after Google's first test, Google ran over 7,000 different A/B tests.


title: A/B testing

text: In 2012, a Microsoft employee working on the search engine Microsoft Bing created an experiment to test different ways of displaying advertising headlines. Within hours, the alternative format produced a revenue increase of 12% with no impact on user-experience metrics. Today, companies like Microsoft and Google each conduct over 10,000 A/B tests annually.


title: A/B testing

text: Many companies now use the "designed experiment" approach to making marketing decisions, with the expectation that relevant sample results can improve positive conversion results. It is an increasingly common practice as the tools and expertise grow in this area.


title: A/B testing

text: A company with a customer database of 2,000 people decides to create an email campaign with a discount code in order to generate sales through its website. It creates two versions of the email with different call to action (the part of the copy which encourages customers to do something — in the case of a sales campaign, make a purchase) and identifying promotional code.


title: A/B testing

text: All other elements of the emails' copy and layout are identical. The company then monitors which campaign has the higher success rate by analyzing the use of the promotional codes. The email using the code A1 has a 5% response rate (50 of the 1,000 people emailed used the code to buy a product), and the email using the code B1 has a 3% response rate (30 of the recipients used the code to buy a product). The company therefore determines that in this instance, the first Call To Action is more effective and will use it in future sales. A more nuanced approach would involve applying statistical testing to determine if the differences in response rates between A1 and B1 were statistically significant (that is, highly likely that the differences are real, repeatable, and not due to random chance).


title: A/B testing

text: In the example above, the purpose of the test is to determine which is the more effective way to encourage customers to make a purchase. If, however, the aim of the test had been to see which email would generate the higher click-rate – that is, the number of people who actually click onto the website after receiving the email – then the results might have been different.


title: A/B testing

text: For example, even though more of the customers receiving the code B1 accessed the website, because the Call To Action didn't state the end-date of the promotion many of them may feel no urgency to make an immediate purchase. Consequently, if the purpose of the test had been simply to see which email would bring more traffic to the website, then the email containing code B1 might well have been more successful. An A/B test should have a defined outcome that is measurable such as number of sales made, click-rate conversion, or number of people signing up/registering.


title: A/B testing

text: A/B testing can be used to determine the right price for the product, as this is perhaps one of the most difficult tasks when a new product or service is launched. A/B testing (especially valid for digital goods) is an excellent way to find out which price-point and offering maximize the total revenue.


title: A/B testing

text: A/B tests have also been used by political campaigns. In 2007, Barack Obama's presidential campaign used A/B testing as a way to garner online attraction and understand what voters wanted to see from the presidential candidate. For example, Obama's team tested four distinct buttons on their website that led users to sign up for newsletters. Additionally, the team used six different accompanying images to draw in users. Through A/B testing, staffers were able to determine how to effectively draw in voters and garner additional interest.


title: A/B testing

text: A/B testing is very common when deploying a newer version of an API. For real-time user experience testing, an HTTP Reverse proxy is configured in such a way that, "N"% of the HTTP traffic goes into the newer version of the backend instance, while the remaining "100-N"% of HTTP traffic hits the (stable) older version of the backend HTTP application service. This is usually done for limiting the exposure of customers to a newer backend instance such that, if there is a bug on the newer version, only "N"% of the total user agents or clients get affected while others get routed to a stable backend, which is a common ingress control mechanism.


title: A/B testing

text: A/B tests most commonly apply the same variant (e.g., user interface element) with equal probability to all users. However, in some circumstances, responses to variants may be heterogeneous. That is, while a variant A might have a higher response rate overall, variant B may have an even higher response rate within a specific segment of the customer base.


title: A/B testing

text: In this case, we can see that while variant A had a higher response rate overall, variant B actually had a higher response rate with men.


title: A/B testing

text: As a result, the company might select a segmented strategy as a result of the A/B test, sending variant B to men and variant A to women in the future. In this example, a segmented strategy would yield an increase in expected response rates from formula_1 to formula_2 – constituting a 30% increase.


title: A/B testing

text: If segmented results are expected from the A/B test, the test should be properly designed at the outset to be evenly distributed across key customer attributes, such as gender. That is, the test should both (a) contain a representative sample of men vs. women, and (b) assign men and women randomly to each “variant” (variant A vs. variant B). Failure to do so could lead to experiment bias and inaccurate conclusions to be drawn from the test.


title: A/B testing

text: This segmentation and targeting approach can be further generalized to include multiple customer attributes rather than a single customer attribute – for example, customers' age "and" gender – to identify more nuanced patterns that may exist in the test results.


title: Cybernetics

text: Cybernetics is a wide-ranging field concerned with circular causality, such as feedback, in regulatory and purposive systems. Cybernetics is named after an example of circular causal feedback, that of steering a ship, where the helmsperson maintains a steady course in a changing environment by adjusting their steering in continual response to the effect it is observed as having. Cybernetics is concerned with circular causal processes such as steering however they are embodied, including in ecological, technological, biological, cognitive, and social systems, and in the context of practical activities such as designing, learning, managing, conversation, and the practice of cybernetics itself. Cybernetics' transdisciplinary and "antidisciplinary" character has meant that it intersects with a number of other fields, leading to it having both wide influence and diverse interpretations.


title: Cybernetics

text: Cybernetics has its origins in exchanges between numerous fields during the 1940s, including anthropology, mathematics, neuroscience, psychology, and engineering. Initial developments were consolidated through meetings such as the Macy Conferences and the Ratio Club. At its most prominent during the 1950s and 1960s, cybernetics is a precursor to fields such as computing, artificial intelligence, cognitive science, complexity science, and robotics amongst others. It is closely related to systems science, which was developed in parallel. Early focuses included purposeful behaviour, neural networks, heterarchy, information theory, and self-organising systems. As cybernetics developed, it became broader in scope to include work in domains such as design, family therapy, management and organisation, pedagogy, sociology, and the creative arts. At the same time, questions arising from circular causality have been explored in relation to the philosophy of science, ethics, and constructivist approaches, while cybernetics has also been associated with counter-cultural movements. Contemporary cybernetics thus varies widely in scope and focus, with cyberneticians variously adopting and combining technical, scientific, philosophical, creative, and critical approaches.


title: Cybernetics

text: Cybernetics has been defined in a variety of ways, reflecting "the richness of its conceptual base". One of the most well known definitions is that of Norbert Wiener who characterised cybernetics as concerned with "control and communication in the animal and the machine". Another early definition is that of the Macy cybernetics conferences, where cybernetics was understood as the study of "circular causal and feedback mechanisms in biological and social systems". Margaret Mead emphasised the role of cybernetics as "a form of cross-disciplinary thought which made it possible for members of many disciplines to communicate with each other easily in a language which all could understand".


title: Cybernetics

text: Other definitions include: “the art of governing or the science of government” (André-Marie Ampère); "the art of steersmanship" (Ross Ashby); "the study of systems of any nature which are capable of receiving, storing, and processing information so as to use it for control" (Andrey Kolmogorov); "a branch of mathematics dealing with problems of control, recursiveness, and information, focuses on forms and the patterns that connect" (Gregory Bateson); "the art of securing efficient operation" (Louis Couffignal); "the art of effective organization." (Stafford Beer); "the science or the art of manipulating defensible metaphors; showing how they may be constructed and what can be inferred as a result of their existence" (Gordon Pask); "the art of creating equilibrium in a world of constraints and possibilities" (Ernst von Glasersfeld); "the science and art of understanding" (Humberto Maturana); "the ability to cure all temporary truth of eternal triteness" (Herbert Brun); "a way of thinking about ways of thinking (of which it is one)" (Larry Richards);


title: Cybernetics

text: According to Norbert Wiener, the word "cybernetics" was coined by a research group involving himself and Arturo Rosenblueth in the summer of 1947. It has been attested in print since at least 1948 through Norbert Wiener's book "". In the book, Wiener states:


title: Cybernetics

text: Moreover, Wiener explains, the term was chosen to recognize James Clerk Maxwell's 1868 publication on feedback mechanisms involving governors, noting that the term "governor" is also derived from κυβερνήτης ("kubernḗtēs") via a Latin corruption "gubernator". Finally, Wiener motivates the choice by steering engines of a ship being "one of the earliest and best-developed forms of feedback mechanisms".


title: Cybernetics

text: Independently, the French term "cybernétique" was used in 1834 by André-Marie Ampère in "Essai sur la philosophie des sciences" to describe the science of civil government.


title: Cybernetics

text: Cybernetics is sometimes understood within the context of systems science, systems theory, and systems thinking.


title: Cybernetics

text: Cybernetics' broad scope and tendency to transgress disciplinary norms means its own boundaries have shifted over time and can be difficult to define. Many fields trace their origins in whole or part to work carried out in cybernetics, or were partially absorbed into cybernetics when it was developed. These include:


title: Cybernetics

text: George Spencer Brown's Laws of Form became influential in cybernetics, including in the work of Francisco Varela, and Louis Kauffman.


title: Cybernetics

text: The notion of eigenform is an example of a self-referential system that produces a stable form. It plays an important role in the work of Heinz von Foerster and is "inextricably linked with second order cybernetics".


title: Cybernetics

text: Feedback is a process where the observed outcomes of actions are taken as inputs for further action in ways that support the pursuit and maintenance of particular conditions or their disruption, forming a circular causal relationship. Cybernetics is named after an example of feedback, that of steering a ship, where the helmsperson maintains a steady course in a changing environment by adjusting their steering in continual response to the effect it is observed as having.


title: Cybernetics

text: Other examples of circular causal feedback include: technological devices such as thermostats (where the action of a heater responds to measured changes in temperature, regulating the temperature of the room within a set range); biological examples such as the coordination of volitional movement through the nervous system; and processes of social interaction such as conversation.


title: Cybernetics

text: Double binds are patterns created in interaction between two or more parties in ongoing relationships where there is a contradiction between messages at different logical levels that creates a situation with emotional threat but no possibility of withdrawal from the situation and no way to articulate the problem. While the theory was first described by Gregory Bateson and colleagues in the 1950s with regard to the origins of schizophrenia, it is also characteristic of many other social contexts.


title: Cybernetics

text: Cybernetics is associated with the enactive approach to cognitive science through the work of Francisco Varela.


title: Cybernetics

text: Radical constructivism is an approach to epistemology developed initially by Ernst von Glasersfeld. It is closely associated with second-order cybernetics.


title: Cybernetics

text: Second-order cybernetics, also known as the cybernetics of cybernetics, is the recursive application of cybernetics to itself and the practice of cybernetics according to such a critique. It has seen development of cybernetics in relation to family therapy, the social sciences, the creative arts, design research, and philosophy. It is associated with Margaret Mead, Heinz von Foerster, the Biological Computer Laboratory and the American Society for Cybernetics.


title: Cybernetics

text: The Ancient Greek term κυβερνητικης (kubernētikēs, '(good at) steering') appears in Plato's the "Republic" and ""Alcibiades"", where the metaphor of a steersman is used to signify the governance of people. The French word "cybernétique" was also used in 1834 by the physicist André-Marie Ampère to denote the sciences of government in his classification system of human knowledge.


title: Cybernetics

text: The first artificial automatic regulatory system was a water clock, invented by the mechanician Ktesibios; based on a tank which poured water into a reservoir before using it to run the mechanism, it used a cone-shaped float to monitor the level of the water in its reservoir and adjust the rate of flow of the water accordingly to maintain a constant level of water in the reservoir. This was the first artificial truly automatic self-regulatory device that required no outside intervention between the feedback and the controls of the mechanism. Devices constructed by Ktesibios and others such as Hero of Alexandria, Philo of Byzantium and Su Song are early examples of cybernetic principles in action.


title: Cybernetics

text: In the late 18th century James Watt's steam engine was equipped with a governor (1775–1800), a centrifugal feedback valve for controlling the speed of the engine. In 1868 James Clerk Maxwell published a theoretical article on governors, one of the first to discuss and refine the principles of self-regulating devices. Jakob von Uexküll applied the feedback mechanism via his model of functional cycle ("Funktionskreis") in order to explain animal behaviour and the origins of meaning in general. Electronic control systems originated with the 1927 work of Bell Telephone Laboratories engineer Harold S. Black on using negative feedback to control amplifiers. In 1935 Russian physiologist P. K. Anokhin published a book in which the concept of feedback ("back afferentation") was studied.


title: Cybernetics

text: The study and mathematical modelling of regulatory processes became a continuing research effort and two key articles were published in 1943: "Behavior, Purpose and Teleology" by Arturo Rosenblueth, Norbert Wiener, and Julian Bigelow –based on the research on living organisms that Arturo Rosenblueth did in Mexico–; and the paper "A Logical Calculus of the Ideas Immanent in Nervous Activity" by Warren McCulloch and Walter Pitts. In the early 1940s John von Neumann contributed a unique and unusual addition to the world of cybernetics: von Neumann cellular automata, and their logical follow up, the von Neumann Universal Constructor. The result of these deceptively simple thought-experiments was the concept of self replication, which cybernetics adopted as a core concept.


title: Cybernetics

text: The foundations of cybernetics were developed through a series of transdisciplinary conferences funded by the Josiah Macy, Jr. Foundation, between 1946 and 1953. The conferences were chaired by McCulloch and had participants included Ross Ashby, Gregory Bateson, Heinz von Foerster, Margaret Mead, John von Neumann, and Norbert Wiener.


title: Cybernetics

text: In the spring of 1947, Wiener was invited to a congress on harmonic analysis, held in Nancy (France was an important geographical locus of early cybernetics together with the US and UK); the event was organized by the Bourbaki and mathematician Szolem Mandelbrojt. During this stay in France, Wiener received the offer to write a manuscript on the unifying character of this part of applied mathematics, which is found in the study of Brownian motion and in telecommunication engineering. The following summer, back in the United States, Wiener decided to introduce the neologism "cybernetics", coined to denote the study of "teleological mechanisms", into his scientific theory: it was popularized through his book "". In the UK this became the focus for the Ratio Club. In 1950, Wiener popularized the social implications of cybernetics, drawing analogies between automatic systems (such as a regulated steam engine) and human institutions in his best-selling "The Human Use of Human Beings: Cybernetics and Society" (Houghton-Mifflin). Published in 1954, Qian Xuesen published work "Engineering Cybernetics" was the basis of science in segregating the engineering concepts of Cybernetics from the theoretical understanding of Cybernetics as described so far historically.


title: Cybernetics

text: Cybernetics in the Soviet Union was initially considered a "pseudoscience" and "ideological weapon" of "imperialist reactionaries" (Soviet Philosophical Dictionary, 1954) and later criticised as a narrow form of cybernetics. In the mid to late 1950s Viktor Glushkov and others salvaged the reputation of the field. Soviet cybernetics incorporated much of what became known as computer science in the West.


title: Cybernetics

text: The design of self-regulating control systems for a real-time planned economy was explored by economist Oskar Lange, cyberneticist Viktor Glushkov, and other Soviet cyberneticists during the 1960s.


title: Cybernetics

text: Cybernetics and socialism have had a complex relationship over the years. Originally lambasted in the Soviet Union, eventually the view of cybernetics shifted to be more positive. Socialist states envisioned large scale cybernetic systems, capable of taking in worker input and processing said data to better centrally plan the socialist economy. Such projects included the Soviet OGAS, or the Chilean Project Cybersyn.


title: Cybernetics

text: Artificial intelligence (AI) was founded as a distinct discipline at the Dartmouth workshop in 1956. After some uneasy coexistence, AI gained funding and prominence. Consequently, cybernetic sciences such as the study of artificial neural networks were downplayed; the discipline shifted into the world of social sciences and therapy.


title: Cybernetics

text: The Biological Computer Laboratory at the University of Illinois at Urbana–Champaign, under the direction of Heinz von Foerster, was a major center of cybernetic research, founded in 1958 and active until the mid-1970s.


title: Cybernetics

text: In the 1970s, new cyberneticians emerged in multiple fields, but especially in biology. The ideas of Maturana, Varela and Atlan, according to Jean-Pierre Dupuy (1986) "realized that the cybernetic metaphors of the program upon which molecular biology had been based rendered a conception of the autonomy of the living being impossible. Consequently, these thinkers were led to invent a new cybernetics, one more suited to the organizations which mankind discovers in nature - organizations he has not himself invented". However, during the 1980s the question of whether the features of this new cybernetics could be applied to social forms of organization remained open to debate.


title: Cybernetics

text: In the 1980s, according to Harries-Jones (1988) "unlike its predecessor, the new cybernetics concerns itself with the interaction of autonomous political actors and subgroups, and the practical and reflexive consciousness of the subjects who produce and reproduce the structure of a political community. A dominant consideration is that of recursiveness, or self-reference of political action both with regards to the expression of political consciousness and with the ways in which systems build upon themselves".


title: Cybernetics

text: One characteristic of the emerging new cybernetics considered in that time by Felix Geyer and Hans van der Zouwen, according to Bailey (1994), was "that it views information as constructed and reconstructed by an individual interacting with the environment. This provides an epistemological foundation of science, by viewing it as observer-dependent. Another characteristic of the new cybernetics is its contribution towards bridging the "micro-macro gap". That is, it links the individual with the society". Another characteristic noted was the "transition from classical cybernetics to the new cybernetics [that] involves a transition from classical problems to new problems. These shifts in thinking involve, among others, (a) a change from emphasis on the system being steered to the system doing the steering, and the factor which guides the steering decisions; and (b) new emphasis on communication between several systems which are trying to steer each other".


title: Cybernetics

text: Recent endeavors into the true focus of cybernetics, systems of control and emergent behavior, by such related fields as game theory (the analysis of group interaction), systems of feedback in evolution, and metamaterials (the study of materials with properties beyond the Newtonian properties of their constituent atoms), have led to a revived interest in the field.


title: Cybernetics

text: Cybernetics' transdisciplinary origins have led to a wide variety of applications, approaches and associations.


title: Cybernetics

text: Many early cyberneticians worked in neurophysiology, including Grey Walter, Warren McCulloch, and Arturo Rosenblueth. This remained a focus as cybernetics developed.


title: Cybernetics

text: Other applications of cybernetics in biology include the physicist George Gamow's article in "Scientific American" called "Information transfer in the living cell", and biologists Jacques Monod and François Jacob use of cybernetics as a language for formulating their early theory of gene regulatory networks in the 1960s.


title: Cybernetics

text: Cybernetics has been used as a general reference for the science between the interjection of disciplines Medicine and technology. This involves sciences such as Bionics, Prosthetics, Neural network, Microchip implants, Neuroprosthetics and Brain-computer interface.


title: Cybernetics

text: Anthropologists working in cybernetics include Gregory Bateson, Margaret Mead, Mary Catherine Bateson, and Genevieve Bell.


title: Cybernetics

text: Concepts from cybernetics spread throughout psychology from the 1950s onwards. The psychological theory, reversal theory, was rooted in cybernetics and continues to be the basis of research and practice.


title: Cybernetics

text: By examining group behavior through the lens of cybernetics, sociologists can seek the reasons for such spontaneous events as smart mobs and riots, as well as how communities develop rules such as etiquette by consensus without formal discussion. Affect Control Theory explains role behavior, emotions, and labeling theory in terms of homeostatic maintenance of sentiments associated with cultural categories.


title: Cybernetics

text: The most comprehensive attempt ever made in the social sciences to increase cybernetics in a generalized theory of society was made by Talcott Parsons. In this way, cybernetics establishes the basic hierarchy in Parsons' AGIL paradigm, which is the ordering system-dimension of his action theory. These and other cybernetic models in sociology are reviewed in a book edited by McClelland and Fararo.


title: Cybernetics

text: Cybernetics has been influential in architecture, especially through the work of Gordon Pask. Pask collaborated with architect Cedric Price and theatre director Joan Littlewood on the influential Fun Palace project during the 1960s and became a consultant to Nicholas Negroponte's Architecture Machine Group, forerunner of the MIT Media Lab. Pask's 1950s Musicolour installation was the inspiration for John and Julia Frazer's work on Price's Generator project.


title: Cybernetics

text: Cybernetic art is contemporary art that builds upon the legacy of cybernetics, where feedback involved in the work takes precedence over traditional aesthetic and material concerns. The relationship between cybernetics and art can be summarised in three ways: cybernetics can be used to study art, to create works of art or may itself be regarded as an art form in its own right.


title: Cybernetics

text: The prominent and influential Cybernetic Serendipity exhibition was held at the Institute of Contemporary Arts in 1968 curated by Jasia Reichardt, including Schöffer's "CYSP I" and Gordon Pask's "Colloquy of Mobiles" installation. Pask's reflections on "Colloquy" connected it to his earlier "Musicolour" installation and to what he termed "aesthetically potent environments", a concept that connected this artistic work to his concerns with teaching and learning.


title: Cybernetics

text: The artist Roy Ascott elaborated an extensive theory of cybernetic art in "Behaviourist Art and the Cybernetic Vision" ("Cybernetica", Journal of the International Association for Cybernetics (Namur), Volume IX, No.4, 1966; Volume X No.1, 1967) and in "The Cybernetic Stance: My Process and Purpose" ("Leonardo" Vol 1, No 2, 1968). Art historian Edward A. Shanken has written about the history of art and cybernetics in essays including "Cybernetics and Art: Cultural Convergence in the 1960s" and "From Cybernetics to Telematics: The Art, Pedagogy, and Theory of Roy Ascott" (2003), which traces the trajectory of Ascott's work from cybernetic art to telematic art (art using computer networking as its medium, a precursor to net.art).


title: Cybernetics

text: Others in the creative arts who are associated with cybernetics, include Herbert Brun, Brian Eno, Ruairi Glynn, Pauline Oliveros, Tom Scholte, and Stephen Willats.


title: Cybernetics

text: Cybernetics was an influence on thinking in design in the decades after the Second World War. Ashby and Pask were drawn on by design theorists such as Horst Rittel, Christopher Alexander and Bruce Archer. Later figures include Ranulph Glanville, Klaus Krippendorff, and Annetta Pedretti.


title: Cybernetics

text: The cybernetic study of design has continued to contribute to design methods and design research and to the development of systemic design and metadesign practices.


title: Cybernetics

text: Cybernetics has been influential in the development of educational technology, notably in the work of Gordon Pask, and in theories of teaching and learning, including Pask's Conversation Theory, Ernst von Glasersfeld's Radical Constructivism, and Gregory Bateson's conception of deuterolearning.


title: Cybernetics

text: Management as a field of study covers the task of managing a multitude of systems (often business systems), which presents a wide natural overlap with many of the classical concepts of cybernetics. Management cybernetics includes approaches such as Stafford Beer's Viable System Model and Syntegration.


title: Cybernetics

text: The development of "family therapy" was significantly influenced by cybernetics through the work of Gregory Bateson, as was the work of R. D. Laing and his work "Knots".


title: Cybernetics

text: The method of levels is an approach to psychotherapy based on perceptual control theory where the therapist aims to help the patient shift their awareness to higher levels of perception in order to resolve conflicts and allow reorganization to take place.


title: Cybernetics

text: A distinctive quality of cybernetics, especially as developed by British cyberneticians, is that it was often progressed through experimental devices and social projects. Notable examples include:


title: Cybernetics

text: Colloquy of Mobiles was an installation by Gordon Pask at the Cybernetic Serendipity exhibition in 1968.


title: Cybernetics

text: The Fun Palace was a radical architectural project developed in the 1960s by the architect Cedric Price, theatre director Joan Littlewood, and cybernetician Gordon Pask. Although unbuilt, the project was widely influential, notably on the design of the Centre Pompidou.


title: Cybernetics

text: The Homeostat was a device built by Ross Ashby that was capable of adapting itself to the environment, exhibited behaviours such as habituation, reinforcement and learning through its ability to maintain homeostasis in a changing environment.


title: Cybernetics

text: Musicolour was an interactive light installation developed by Gordon Pask during the 1950s. It responded to musicians' variations and, if they did not vary their playing, it would become 'bored' and stop responding, prompting the musicians to respond.


title: Cybernetics

text: Project Cybersyn attempted to apply cybernetics to the economy at large scale during the early 1970s.


title: Cybernetics

text: The School for Designing a Society is a project of teachers, performers, artists, and activists, influenced by cybernetics, where the question “What would I consider a desirable society?” is given serious playful thoughtful discussion. Founders and guests include Susan Parenti, Mark Enslin, Herbert Brun, and Larry Richards. A premise of the school was that social change can be realized in a transformation from the current to a new society (a change of system), not only in improvements to the current society (changes in a system).


title: Cybernetics

text: Gregory Bateson saw the world as a series of systems containing those of individuals, societies and ecosystems. Each of these systems has adaptive changes which depend upon feedback loops to control balance by changing multiple variables. He saw the natural ecological system as innately good as long as it was allowed to maintain homeostasis, and that the key unit of survival in evolution was an organism and its environment.


title: Cybernetics

text: Bateson, in this subject, presents western epistemology as a method of thinking that leads to a mindset in which man exerts an autocratic rule over all cybernetic systems and in doing so he unbalances the natural cybernetic system of controlled competition and mutual dependency. Bateson claims that humanity will never be able to control the whole system because it does not operate in a linear fashion, and if humanity creates his own rules for the system, he opens himself up to becoming a slave to the self-made system due to the non-linear nature of cybernetics. Lastly, man's technological prowess combined with his scientific hubris gives him the potential to irrevocably damage and destroy the "supreme cybernetic system" (i.e. the biosphere), instead of just disrupting the system temporally until the system can self-correct.


title: Cybernetics

text: Second-order cybernetics is associated with a radically constructivist approach to epistemology and the philosophy of science.


title: Cybernetics

text: The critique of objectivity developed in second-order cybernetics led to a concern with ethical issues. Foerster developed a critique of morality in ethical terms, arguing for ethics to remain implicit in action. Foerster's position has been described as an "ethics of enabling ethics" or as a form of "recursive ethical questioning". Varela published a short book on "ethical know-how". Glanville identified a number of "desirable" ethical qualities implicit in the cybernetic devices of the black box, distinction, autonomy, and conversation. Others have drawn connections to design and critical systems heuristics.


title: Cybernetics

text: Cybernetics was influential on the development of countercultural movements through figures such as Stewart Brand and publications such as the Whole Earth Catalogue and Co-Evolution Quarterly.


title: Cybernetics

text: Ideas from cybernetics have influenced feminisms through the work of Margaret Mead, Mary Catherine Bateson, Donna Haraway, and Sadie Plant.


title: Cybernetics

text: The Gaia hypothesis was informed by the first wave of cybernetic concepts - homeostasis, self-organization, negative feedback, and self-regulation - and later by the second-order cybernetic theory of autopoiesis.


title: Cybernetics

text: Friedrich Hayek refers to cybernetics as a discipline that could help economists understand the "self-organizing or self-generating systems" called markets.


title: Cybernetics

text: Cybernetics' relevance across and between the domains of have been an influence on the development of posthumanism, such as in the work of N. Katherine Hayles.


title: Cybernetics

text: The Metaphorum group was set up in 2003 to develop Stafford Beer's legacy in Organizational Cybernetics. The Metaphorum Group was born in a Syntegration in 2003 and have every year after developed a Conference on issues related to Organizational Cybernetics' theory and practice.


title: Cybernetics

text: RC51 is a research committee of the International Sociological Association promoting the development of (socio)cybernetic theory and research within the social sciences.


title: Cybernetics

text: SCiO (Systems and Complexity in Organisation) is a community of systems practitioners who believe that traditional approaches to running organisations are no longer capable of dealing with the complexity and turbulence faced by organisations today and are responsible for many of the problems we see today.


title: Cybernetics

text: SCiO is the Body of Knowledge in Systems Practice in the UK, delivers a apprenticeship on masters level and a certification in systems practice.


title: So I'm a Spider, So What?

text: In a world where the battle between Hero and Demon Lord repeated itself time and time again, an enormous space-time spell misfired and hit a certain Japanese high school class on Earth, killing everyone in it. However, guided by what seemed to be a miracle, the students were all reincarnated into that other world. While a handful was fortunate enough to become royalty, nobles, and other kinds of influential people, one girl was not so lucky. Being reborn as a spider monster of the weakest kind in a dungeon filled with vicious beasts, she is forced to experience extreme hardship. Even so, armed with nothing but her human knowledge and overwhelming positivity, she continues to press on and survive against creatures much stronger than herself.


title: So I'm a Spider, So What?

text: Okina Baba originally serialized the series as a web novel on the user-generated content site Shōsetsuka ni Narō starting on May 27, 2015. Fujimi Shobo acquired the series for print publication, and published the first light novel, with illustrations by Tsukasa Kiryu, in December 2015. Yen Press announced during their panel at Sakura-Con on April 15, 2017, that they had licensed the series. The series' main story ended with its 16th volume released on January 8, 2022.


title: So I'm a Spider, So What?

text: Asahiro Kakashi launched a manga adaptation of the web novels on the Kadokawa Shoten's "Young Ace Up" manga website on December 22, 2015. The manga is also licensed by Yen Press.


title: So I'm a Spider, So What?

text: It was reported on July 6, 2018, that the series would receive an anime adaptation, according to an early look at the wraparound jacket band on the fifth volume of the manga adaptation. The report was confirmed at Kadokawa's booth at Anime Expo later that day, and it was announced that the adaptation would be a television series. Originally set to premiere in 2020, it was rescheduled to premiere in January 2021 due to the COVID-19 pandemic. The two-cour (24 episode) series was animated by Millepensee and directed by Shin Itagaki, with Okina Baba and Yūichirō Momose overseeing the series' scripts, and Kii Tanaka designing the characters, Shūji Katayama composing the series' music, and Jōtarō Ishigami producing the series. The series aired from January 8 to July 3, 2021, on AT-X and other channels. The first opening theme song is "keep weaving your spider way" performed by Riko Azuna, while the first ending theme song is performed by I (Aoi Yūki). The second opening theme is "Bursty Greedy Spider" performed by Konomi Suzuki, while the second ending theme is by Yūki. It is licensed by Crunchyroll outside Asia. Medialink has licensed the series in Southeast Asia and South Asia, and is streaming it on their Ani-One YouTube channel and Bilibili. The final episode was delayed due to production issues and aired one week later on July 3, 2021.


title: So I'm a Spider, So What?

text: The light novels and manga had a combined 1.2 million copies in print as of July 2018. The light novels ranked third in the "tankōbon" category in the "Kono Light Novel ga Sugoi!" 2017 rankings, and second in the 2018 rankings.


title: Tomie

text: The manga has been adapted into a live-action film series with eight installments to date, an anthology released in 1999, and a streaming television series was in development for Quibi before the service was shut down.


title: Tomie

text: The manga centers on the titular character: a mysterious, beautiful woman named Tomie Kawakami, identified by her sleek black hair and a beauty mark below her left eye.


title: Tomie

text: Tomie acts like a succubus, possessing an undisclosed power to make any man fall in love with her. Through her mere presence, or through psychological and emotional manipulation, she drives these people into jealous rages that often lead to brutal acts of violence. Men kill each other over her, and women are driven to insanity as well — though there are some who are strong enough to resist her. Tomie is inevitably killed time and time again, only to regenerate and spread her curse to other victims, making her effectively immortal. Her origins are never explained, though it is suggested by some older men in the series that she has existed long before the events of the manga; in "Boy", she is revealed to have known her future teacher Satoru Takagi since he was a child.


title: Tomie

text: Each story showcases various characters that encounter Tomie in her many (often hideous) forms, with some having their own arcs or returning in later chapters. Tomie's regenerative abilities (partly fuelled by cannibalism and assimilation) are also showcased: aside from recovering quickly from gruesome and seemingly mortal wounds, she can also replicate herself by sprouting unnaturally from any part of her body, whether it be from severed limbs, organs, or even her spilled blood. Radiation accelerates her healing/regeneration process. Her cells are also capable of transforming a victim into a Tomie via an organ transplant. Multiple characters are even driven to dismember her corpse, unwittingly allowing more Tomie copies to grow and spread throughout the world. Even locks of her hair are dangerous; burrowing into its victim's brain to possess them, and eventually kill them when it grows wildly within the body. It is also shown that even if Tomie's body is not injured, her body will attempt to sprout another Tomie through tumorous growths, usually when she is emotionally stressed. Some Tomie copies, however, cannot stand one another; one is seen killing one personally, while others order it done through the boys they seduce/enslave. Fire is the only known method to destroy a Tomie for good, though only if the flesh is completely carbonized.


title: Tomie

text: The next story arc, beginning as a prequel, reveals that a baby girl can grow naturally into a Tomie via a blood injection and that she can age if she has not yet copied herself. The man responsible for these injections is a horribly burnt stranger — once a supermodel disgraced by a Tomie in his past — who seeks revenge by making one of these "natural" Tomies old and ugly. He manages to encase a Tomie named "Ayaka" in a block of cement with the help of Ayaka's older sister. The two then wait for many years — endlessly hearing her tormented cries — before finally breaking the block, revealing that Tomie had somehow escaped through a tiny crack, her apparent wailing being nothing more than wind blowing through the hollow block.


title: Tomie

text: An arc released exclusively with the DVD release of the "Junji Ito Collection", titled "Tomie: Takeover", features Tomie encountering a man capable of body-switching, who finds her various abilities difficult to handle.


title: Tomie

text: A four-page crossover arc with Souichi Tsujii, titled "Souichi Possessed", was released in 2018. In the story, the titular's Souichi's older brother Koichi tells a younger Tomie of his attempted mischief of a brother's encounter with a different elderly Tomie, the arc serving as the prologue to a larger confrontation between the pair, as the younger Tomie requests an introduction.


title: Tomie

text: "Tomie" is published by Asahi Sonorama and appeared as a serial in the manga magazine "Monthly Halloween" from 1987 to 2000. Tomie received one bound volume in February 1996, titled . Two volumes were collected into the overarching series as volume 1 and 2 of the series. Asahi Sonorama released an omnibus volume in February 2000 titled, . ComicsOne released both volumes on April 1, 2001, with flipped artwork (read left-to-right).


title: Tomie

text: A second series titled was serialized in "Nemuki" and was collected into a single bound volume titled and released in March 2001. "Tomie" was re-released again as part of series. This version was also released in two volumes with the addition of the chapters originally released in "Tomie Again". Dark Horse Comics released this version in its original right-to-left format.


title: Tomie

text: Viz Media announced their license to the series on March 26, 2016. They published it as a single hardcover volume, similar to their releases of "Gyo" and "Uzumaki".


title: Tomie

text: "Tomie" has been adapted into a series of Japanese horror films released between 1999 and 2011. There are to date nine films in the series.


title: Tomie

text: Most of the manga stories occur during the dark of night for its sense of eeriness, and the films generally follow suit.


title: Tomie

text: Tomie's sexuality in films is more ambiguous. In the manga, Tomie's attitude towards women seems to range between thinly-veiled hostility and outright murderous rage (unless she stands to profit from them), while the film incarnation is known to seduce women as well as men.


title: Tomie

text: In July 2019, Alexandre Aja was announced to be developing a web television series adaptation of "Tomie" for Quibi, in conjunction with Sony Pictures Television and Universal Content Productions, with David Leslie Johnson-McGoldrick serving as writer and executive producer and Hiroki Shirota on board as co-producer. In July 2020, Adeline Rudolph was announced to have been cast as Tomie. In October 2020, it was announced that Quibi is shutting down on December 1, 2020, leaving the fate of the series in question.


title: Tomie

text: Junji Ito won the 1989 Kazuo Umezu Prize for his work on "Tomie". Since then, the manga has spawned a cult following and is still generally praised by fans and critics alike.


title: Van Allen radiation belt

text: A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a planet by that planet's magnetosphere. Earth has two such belts, and sometimes others may be temporarily created. The belts are named after James Van Allen, who is credited with their discovery. Earth's two main belts extend from an altitude of about above the surface, in which region radiation levels vary. Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction.


title: Van Allen radiation belt

text: The belts are in the inner region of Earth's magnetic field. The belts trap energetic electrons and protons. Other nuclei, such as alpha particles, are less prevalent. The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend significant time near that zone. In 2013, the Van Allen Probes detected a transient, third radiation belt, which persisted for four weeks. Apollo Astronauts going through the Van Allen Belts received a very low and non-harmful dose of radiation.


title: Van Allen radiation belt

text: Kristian Birkeland, Carl Størmer, Nicholas Christofilos, and Enrico Medi had investigated the possibility of trapped charged particles before the Space Age. Explorer 1 and Explorer 3 confirmed the existence of the belt in early 1958 under James Van Allen at the University of Iowa. The trapped radiation was first mapped by Explorer 4, Pioneer 3, and Luna 1.


title: Van Allen radiation belt

text: The term "Van Allen belts" refers specifically to the radiation belts surrounding Earth; however, similar radiation belts have been discovered around other planets. The Sun does not support long-term radiation belts, as it lacks a stable, global dipole field. The Earth's atmosphere limits the belts' particles to regions above 200–1,000 km, (124–620 miles) while the belts do not extend past 8 Earth radii "R". The belts are confined to a volume which extends about 65° on either side of the celestial equator.


title: Van Allen radiation belt

text: The NASA Van Allen Probes mission aims at understanding (to the point of predictability) how populations of relativistic electrons and ions in space form or change in response to changes in solar activity and the solar wind.


title: Van Allen radiation belt

text: NASA Institute for Advanced Concepts–funded studies have proposed magnetic scoops to collect antimatter that naturally occurs in the Van Allen belts of Earth, although only about 10 micrograms of antiprotons are estimated to exist in the entire belt.


title: Van Allen radiation belt

text: The Van Allen Probes mission successfully launched on August 30, 2012. The primary mission was scheduled to last two years with expendables expected to last four. The probes were deactivated in 2019 after running out of fuel and are expected to deorbit during the 2030s. NASA's Goddard Space Flight Center manages the Living With a Star program—of which the Van Allen Probes were a project, along with Solar Dynamics Observatory (SDO). The Applied Physics Laboratory was responsible for the implementation and instrument management for the Van Allen Probes.


title: Van Allen radiation belt

text: Radiation belts exist around other planets and moons in the solar system that have magnetic fields powerful enough to sustain them. To date, most of these radiation belts have been poorly mapped. The Voyager Program (namely Voyager 2) only nominally confirmed the existence of similar belts around Uranus and Neptune.


title: Van Allen radiation belt

text: Geomagnetic storms can cause electron density to increase or decrease relatively quickly (i.e., approximately one day or less). Longer-timescale processes determine the overall configuration of the belts. After electron injection increases electron density, electron density is often observed to decay exponentially. Those decay time constants are called "lifetimes." Measurements from the Van Allen Probe B's Magnetic Electron Ion Spectrometer (MagEIS) show long electron lifetimes (i.e., longer than 100 days) in the inner belt; short electron lifetimes of around one or two days are observed in the "slot" between the belts; and energy-dependent electron lifetimes of roughly five to 20 days are found in the outer belt.


title: Van Allen radiation belt

text: The inner Van Allen Belt extends typically from an altitude of 0.2 to 2 Earth radii (L values of 1 to 3) or to above the Earth. In certain cases, when solar activity is stronger or in geographical areas such as the South Atlantic Anomaly, the inner boundary may decline to roughly 200 km above the Earth's surface. The inner belt contains high concentrations of electrons in the range of hundreds of keV and energetic protons with energies exceeding 100 MeV—trapped by the relatively strong magnetic fields in the region (as compared to the outer belt).


title: Van Allen radiation belt

text: It is believed that proton energies exceeding 50 MeV in the lower belts at lower altitudes are the result of the beta decay of neutrons created by cosmic ray collisions with nuclei of the upper atmosphere. The source of lower energy protons is believed to be proton diffusion, due to changes in the magnetic field during geomagnetic storms.


title: Van Allen radiation belt

text: Due to the slight offset of the belts from Earth's geometric center, the inner Van Allen belt makes its closest approach to the surface at the South Atlantic Anomaly.


title: Van Allen radiation belt

text: In March 2014, a pattern resembling "zebra stripes" was observed in the radiation belts by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) onboard Van Allen Probes. The initial theory proposed in 2014 was that—due to the tilt in Earth's magnetic field axis—the planet's rotation generated an oscillating, weak electric field that permeates through the entire inner radiation belt. A 2016 study instead concluded that the zebra stripes were an imprint of ionospheric winds on radiation belts.


title: Van Allen radiation belt

text: The outer belt consists mainly of high-energy (0.1–10 MeV) electrons trapped by the Earth's magnetosphere. It is more variable than the inner belt, as it is more easily influenced by solar activity. It is almost toroidal in shape, beginning at an altitude of 3 Earth radii and extending to 10 Earth radii ("R")— above the Earth's surface. Its greatest intensity is usually around 4 to 5 "R". The outer electron radiation belt is mostly produced by inward radial diffusion and local acceleration due to transfer of energy from whistler-mode plasma waves to radiation belt electrons. Radiation belt electrons are also constantly removed by collisions with Earth's atmosphere, losses to the magnetopause, and their outward radial diffusion. The gyroradii of energetic protons would be large enough to bring them into contact with the Earth's atmosphere. Within this belt, the electrons have a high flux and at the outer edge (close to the magnetopause), where geomagnetic field lines open into the geomagnetic "tail", the flux of energetic electrons can drop to the low interplanetary levels within about —a decrease by a factor of 1,000.


title: Van Allen radiation belt

text: In 2014, it was discovered that the inner edge of the outer belt is characterized by a very sharp transition, below which highly relativistic electrons (> 5MeV) cannot penetrate. The reason for this shield-like behavior is not well understood.


title: Van Allen radiation belt

text: The trapped particle population of the outer belt is varied, containing electrons and various ions. Most of the ions are in the form of energetic protons, but a certain percentage are alpha particles and O oxygen ions—similar to those in the ionosphere but much more energetic. This mixture of ions suggests that ring current particles probably originate from more than one source.


title: Van Allen radiation belt

text: The outer belt is larger than the inner belt, and its particle population fluctuates widely. Energetic (radiation) particle fluxes can increase and decrease dramatically in response to geomagnetic storms, which are themselves triggered by magnetic field and plasma disturbances produced by the Sun. The increases are due to storm-related injections and acceleration of particles from the tail of the magnetosphere.


title: Van Allen radiation belt

text: On February 28, 2013, a third radiation belt—consisting of high-energy ultrarelativistic charged particles—was reported to be discovered. In a news conference by NASA's Van Allen Probe team, it was stated that this third belt is a product of coronal mass ejection from the Sun. It has been represented as a separate creation which splits the Outer Belt, like a knife, on its outer side, and exists separately as a storage container of particles for a month's time, before merging once again with the Outer Belt.


title: Van Allen radiation belt

text: The unusual stability of this third, transient belt has been explained as due to a 'trapping' by the Earth's magnetic field of ultrarelativistic particles as they are lost from the second, traditional outer belt. While the outer zone, which forms and disappears over a day, is highly variable due to interactions with the atmosphere, the ultrarelativistic particles of the third belt are thought not to scatter into the atmosphere, as they are too energetic to interact with atmospheric waves at low latitudes. This absence of scattering and the trapping allows them to persist for a long time, finally only being destroyed by an unusual event, such as the shock wave from the Sun.


title: Van Allen radiation belt

text: In the belts, at a given point, the flux of particles of a given energy decreases sharply with energy.


title: Van Allen radiation belt

text: At the magnetic equator, electrons of energies exceeding 5000 keV (resp. 5 MeV) have omnidirectional fluxes ranging from 1.2×10 (resp. 3.7×10) up to 9.4×10 (resp. 2×10) particles per square centimeter per second.


title: Van Allen radiation belt

text: The proton belts contain protons with kinetic energies ranging from about 100 keV, which can penetrate 0.6 µm of lead, to over 400 MeV, which can penetrate 143 mm of lead.


title: Van Allen radiation belt

text: Most published flux values for the inner and outer belts may not show the maximum probable flux densities that are possible in the belts. There is a reason for this discrepancy: the flux density and the location of the peak flux is variable, depending primarily on solar activity, and the number of spacecraft with instruments observing the belt in real time has been limited. The Earth has not experienced a solar storm of Carrington event intensity and duration, while spacecraft with the proper instruments have been available to observe the event.


title: Van Allen radiation belt

text: Radiation levels in the belts would be dangerous to humans if they were exposed for an extended period of time. The Apollo missions minimised hazards for astronauts by sending spacecraft at high speeds through the thinner areas of the upper belts, bypassing inner belts completely, except for the Apollo 14 mission where the spacecraft traveled through the heart of the trapped radiation belts.


title: Van Allen radiation belt

text: In 2011, a study confirmed earlier speculation that the Van Allen belt could confine antiparticles. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiment detected levels of antiprotons orders of magnitude higher than are expected from normal particle decays while passing through the South Atlantic Anomaly. This suggests the Van Allen belts confine a significant flux of antiprotons produced by the interaction of the Earth's upper atmosphere with cosmic rays. The energy of the antiprotons has been measured in the range from 60 to 750 MeV.


title: Van Allen radiation belt

text: Research funded by the NASA Institute for Advanced Concepts concluded that harnessing these antiprotons for spacecraft propulsion would be feasible. Researchers believed that this approach would have advantages over antiproton generation at CERN because collecting the particles in situ eliminates transportation losses and costs. Jupiter and Saturn are also possible sources, but the Earth belt is the most productive. Jupiter is less productive than might be expected due to magnetic shielding from cosmic rays of much of its atmosphere. In 2019, CMS announced that the construction of a device that would be capable of collecting these particles has already begun. NASA will use this device to collect these particles and transport them to institutes all around the world for further examination. These so-called "antimatter containers" could be used for industrial purposes as well in the future.


title: Van Allen radiation belt

text: Spacecraft travelling beyond low Earth orbit enter the zone of radiation of the Van Allen belts. Beyond the belts, they face additional hazards from cosmic rays and solar particle events. A region between the inner and outer Van Allen belts lies at 2 to 4 Earth radii and is sometimes referred to as the "safe zone".


title: Van Allen radiation belt

text: Solar cells, integrated circuits, and sensors can be damaged by radiation. Geomagnetic storms occasionally damage electronic components on spacecraft. Miniaturization and digitization of electronics and logic circuits have made satellites more vulnerable to radiation, as the total electric charge in these circuits is now small enough so as to be comparable with the charge of incoming ions. Electronics on satellites must be hardened against radiation to operate reliably. The Hubble Space Telescope, among other satellites, often has its sensors turned off when passing through regions of intense radiation. A satellite shielded by 3 mm of aluminium in an elliptic orbit () passing the radiation belts will receive about 2,500 rem (25 Sv) per year. (For comparison, a full-body dose of 5 Sv is deadly.) Almost all radiation will be received while passing the inner belt.


title: Van Allen radiation belt

text: The Apollo missions marked the first event where humans traveled through the Van Allen belts, which was one of several radiation hazards known by mission planners. The astronauts had low exposure in the Van Allen belts due to the short period of time spent flying through them.


title: Van Allen radiation belt

text: Astronauts' overall exposure was actually dominated by solar particles once outside Earth's magnetic field. The total radiation received by the astronauts varied from mission-to-mission but was measured to be between 0.16 and 1.14 rads (1.6 and 11.4 mGy), much less than the standard of 5 rem (50 mSv) per year set by the United States Atomic Energy Commission for people who work with radioactivity.


title: Van Allen radiation belt

text: It is generally understood that the inner and outer Van Allen belts result from different processes. The inner belt—consisting mainly of energetic protons—is the product of the decay of so-called "albedo" neutrons, which are themselves the result of cosmic ray collisions in the upper atmosphere. The outer belt consists mainly of electrons. They are injected from the geomagnetic tail following geomagnetic storms, and are subsequently energized through wave-particle interactions.


title: Van Allen radiation belt

text: In the inner belt, particles that originate from the Sun are trapped in the Earth's magnetic field. Particles spiral along the magnetic lines of flux as they move "latitudinally" along those lines. As particles move toward the poles, the magnetic field line density increases, and their "latitudinal" velocity is slowed and can be reversed—reflecting the particles and causing them to bounce back and forth between the Earth's poles. In addition to the spiral about and motion along the flux lines, the electrons move slowly in an eastward direction, while the ions move westward.


title: Van Allen radiation belt

text: A gap between the inner and outer Van Allen belts—sometimes called safe zone or safe slot—is caused by the Very Low Frequency (VLF) waves, which scatter particles in pitch angle, which results in the gain of particles to the atmosphere. Solar outbursts can pump particles into the gap, but they drain again in a matter of days. The radio waves were originally thought to be generated by turbulence in the radiation belts, but recent work by James L. Green of the Goddard Space Flight Center—comparing maps of lightning activity collected by the Microlab 1 spacecraft with data on radio waves in the radiation-belt gap from the IMAGE spacecraft—suggests that they are actually generated by lightning within Earth's atmosphere. The generated radio waves strike the ionosphere at the correct angle to pass through only at high latitudes, where the lower ends of the gap approach the upper atmosphere. These results are still under scientific debate.


title: Van Allen radiation belt

text: Draining the charged particles from the Van Allen belts would open up new orbits for satellites and make travel safer for astronauts.


title: Van Allen radiation belt

text: High Voltage Orbiting Long Tether, or HiVOLT, is a concept proposed by Russian physicist V. V. Danilov and further refined by Robert P. Hoyt and Robert L. Forward for draining and removing the radiation fields of the Van Allen radiation belts that surround the Earth.


title: Van Allen radiation belt

text: Another proposal for draining the Van Allen belts involves beaming very-low-frequency (VLF) radio waves from the ground into the Van Allen belts.


title: Van Allen radiation belt

text: Draining radiation belts around other planets has also been proposed, for example, before exploring Europa, which orbits within Jupiter's radiation belt.


title: Van Allen radiation belt

text: As of 2014, it remains uncertain if there are any negative unintended consequences to removing these radiation belts.


title: Dejounte Murray

text: Dejounte Dashaun Murray ( ; born September 19, 1996) is an American professional basketball player for the Atlanta Hawks of the National Basketball Association (NBA). He played one season of college basketball for the Washington Huskies, where he earned second-team all-conference honors in the Pac-12 as a freshman in 2015–16. He was selected by the San Antonio Spurs in the first round of the 2016 NBA draft with the 29th overall pick. In 2022, Murray was named to his first NBA All-Star Game and led the league in steals. He is the Spurs' franchise leader in career triple-doubles.


title: Dejounte Murray

text: Murray attended Rainier Beach High School in Seattle, Washington. The school is a basketball powerhouse, having produced such NBA talents as Jamal Crawford, Doug Christie, Terrence Williams, Nate Robinson and Kevin Porter Jr. Murray led the Vikings to three Class 3A state championships titles. Among other honors that he received, Murray was named Washington Mr. Basketball by the Washington Interscholastic Basketball Coaches Association as well as The Seattle Times State Player of the Year.


title: Dejounte Murray

text: As a freshman at the University of Washington in 2015–16, Murray was named second-team All-Pac-12 and Pac-12 All-Freshman Team after averaging 16.1 points, 5.9 rebounds, 4.4 assists and 1.8 steals in 33.5 minutes while starting all 34 games.


title: Dejounte Murray

text: On March 23, 2016, Murray declared for the NBA draft, forgoing his final three years of college eligibility.


title: Dejounte Murray

text: On June 23, 2016, Murray was selected by the San Antonio Spurs with the 29th overall pick in the 2016 NBA draft. He joined the Spurs for the 2016 NBA Summer League, and on July 14, he signed his rookie scale contract with the team. On October 29, 2016, in the Spurs' third game of the 2016–17 season, Murray made his NBA debut. In just under nine minutes off the bench, he recorded two rebounds and one assist in a 98–79 win over the New Orleans Pelicans. On January 12, 2017, he scored a season-high 10 points in a 134–94 win over the Los Angeles Lakers. He surpassed that mark on January 19, scoring 24 points in a 118–104 win over the Denver Nuggets. During his rookie season, he had multiple assignments with the Austin Spurs of the NBA Development League.


title: Dejounte Murray

text: On May 5, 2017, with Tony Parker ruled out for the rest of the playoffs with a leg injury, the Spurs opted to start Murray at point guard in Game 3 of their second-round series against the Houston Rockets. He scored two points in 15 minutes, as the Spurs took a 2–1 lead in the series with a 103–92 win. He helped the Spurs clinch the series against the Rockets with 11 points, 10 rebounds and 5 assists in a Game 6 win. He became just the fourth rookie in Spurs history to record a point/rebound double-double in a playoff game, joining David Robinson, Tim Duncan, and Kawhi Leonard. The Spurs went on to lose to the Golden State Warriors in the Western Conference Finals.


title: Dejounte Murray

text: In the Spurs' season opener on October 18, 2017, Murray had 16 points, five rebounds, and two assists while starting in place of Parker in a 107–99 win over the Minnesota Timberwolves. On December 9, 2017, he tied his career-high with 14 rebounds in a 104–101 win over the Phoenix Suns. On February 3, 2018, in a 120–111 loss to the Utah Jazz, Murray became the first player since Kawhi Leonard with 500 points and 300 rebounds in his first 100 games with the Spurs. On March 19, 2018, in an 89–75 win over the Warriors, Murray had eight rebounds to set the franchise record for rebounds in a single season by a point guard. Murray reached 385 rebounds in 1,436 minutes, surpassing Johnny Moore's total of 378 collected in 2,689 minutes. In Game 4 of the Spurs' first-round playoff series against the Warriors, Murray was 3-for-3 on 3-pointers in the first half, the most three-pointers made in the playoffs without a miss by a Spurs player since Steve Kerr (2003) and Patty Mills (2014) were 4-for-4 in a half. At the season's end, he earned NBA All-Defensive Second Team honors, becoming the youngest player in NBA history to be named All-Defense.


title: Dejounte Murray

text: On October 7, 2018, Murray suffered a torn right anterior cruciate ligament injury in a preseason game against the Rockets. He subsequently missed the entire 2018–19 season.


title: Dejounte Murray

text: In October 2019, the Spurs and Murray agreed to a $64 million, four-year contract, taking the contract to $70 million with incentives.


title: Dejounte Murray

text: On December 26, 2020, Murray recorded his first career triple-double with 11 points, 10 rebounds and 10 assists in the Spurs' 119–114 win against the Toronto Raptors. On February 8, 2021, he recorded 27 points, 10 rebounds, and a career-high eight steals in the Spurs' 105–100 win against the Warriors.


title: Dejounte Murray

text: On February 7, he was named to his first NBA All-Star team as an injury replacement for Draymond Green. On February 13, in a 124–114 win over the Pelicans, Murray became the first player in NBA history to record at least 30 points, 10 rebounds, and no more than one turnover in consecutive games since individual turnovers were first tracked in 1977–78. He finished second, behind Ja Morant, in voting for the Most Improved Player award. Murray finished the 2022 season as the first player in NBA history to average 20 points, 8 rebounds, 9 assists and 2 steals a game.


title: Dejounte Murray

text: On June 30, 2022, Murray was traded, alongside Jock Landale, to the Atlanta Hawks in exchange for Danilo Gallinari and multiple future first-round picks. On October 19, Murray made his Hawks debut, putting up 20 points, 11 assists, five rebounds, and five steals in a 117–107 win over the Houston Rockets. On November 2, Murray recorded a then career high 36 points, along with 4 rebounds, 9 assists, and 6 steals in a 112–99 win against the New York Knicks. On November 5, Murray recorded his first career triple-double with the Hawks, putting up 22 points, 10 rebounds, 11 assists, and 3 steals in a 124–121 overtime win against the New Orleans Pelicans. On November 25, Murray recorded a career-high 39 points on eight three-pointers made in a 128–122 loss against the Houston Rockets.


title: Scythia

text: Scythia (Scythian: ; Old Persian: ; Ancient Greek: ; Latin: ) or Scythica (Ancient Greek: ; Latin: ), also known as Pontic Scythia, was a kingdom created by the Scythians during the 6th to 3rd centuries BC in the Pontic–Caspian steppe.


title: Scythia

text: The Scythians originated in Central Asia possibly around the 9th century BC, and they arrived in the Caucasian Steppe in the 8th and 7th centuries BC as part of a significant movement of the nomadic peoples of the Eurasian Steppe. This movement started when another nomadic Iranian tribe closely related to the Scythians, either the Massagetae or the Issedones, migrated westwards, forcing the Early Scythians to the west across the Araxes river, following which the Scythians moved into the Caspian Steppe, where they conquered the territory of the Cimmerians, who were also a nomadic Iranian people closely related to the Scythians, and assimilated most of them while displacing the rest, before settling in the area between the Araxes, the Caucasus Mountains and the Lake Maeotis.


title: Scythia

text: During this early migratory period, some groups of Scythians settled in Ciscaucasia and the foothills of the Caucasus Mountains to the east of the Kuban river, where they settled among the native populations of this region, and did not migrate to the south into West Asia.


title: Scythia

text: Under Scythian pressure, the displaced Cimmerians migrated to the south along the coast of the Black Sea and reached Anatolia, and the Scythians in turn later expanded to the south, following the coast of the Caspian Sea and arrived in the steppes in Ciscaucasia, from where they expanded into the region of present-day Azerbaijan, where they settled and turned eastern Transcaucasia into their centre of operations in West Asia until the early 6th century BC, with this presence in West Asia being an extension of the Scythian kingdom of the steppes. During this period, the Scythian kings' headquarters were located in the Ciscaucasian steppes, and contact with the civilisation of West Asia would have an important influence on the formation of Scythian culture.


title: Scythia

text: From their base in the Caucasian Steppe, during the period of the 8th to 7th centuries BC itself, the Scythians conquered the Pontic Steppe to the north of the Black Sea up to the Danube river, which formed the western boundary of Scythian territory onwards, although the Scythians may also have had access to the Wallachian and Moldavian plains. This expansion displaced another nomadic Iranian people related to the Scythians, the Agathyrsi, who were the oldest Iranian population to have dominated the Pontic Steppe, and who were pushed westwards by the Scythians, away from the steppes and from their original home around Lake Maeotis, after which the relations between the two populations remained hostile. Within the Pontic steppe, some of the Scythian tribes intermarried with the already present native sedentary Thracian populations to form new tribes such as the Nomadic Scythians and the Alazones.


title: Scythia

text: Using the Pontic steppe as their base, the Scythians over the course of the 7th to 6th centuries BC often raided into the adjacent regions, with Central Europe being a frequent target of their raids, and Scythian incursions reaching Podolia, Transylvania, and the Hungarian Plain, due to which, beginning in this period, new objects, including weapons and horse-equipment, originating from the steppes and remains associated with the early Scythians started appearing within Central Europe, especially in the Thracian and Hungarian plains, and in the regions corresponding to present-day Bessarabia, Transylvania, Hungary, and Slovakia, from the end of the 7th century onwards. Multiple fortified settlements of the Lusatian culture were destroyed by Scythian attacks during this period, with the Scythian onslaught causing the destruction of the Lusatian culture itself. Attacks by the Scythians were directed at southern Germania, and, from there, until as far as Gaul and even the Iberian Peninsula; these activities of the Scythians were not unlike those of the Huns and the Avars during the Migration Period and of the Mongols in the mediaeval era, and they were recorded in Etruscan bronze figurines depicting mounted Scythian archers as well as in Scythian influences in Celtic art.


title: Scythia

text: As part of the Scythians' expansion into Europe, one section of the Scythian Sindi tribe migrated during the 7th to 6th centuries BC from the region of the Lake Maeotis towards the west, through Transylvania into the eastern Pannonian basin, where they settled alongside the Sigynnae and soon lost contact with the Scythians of the Pontic steppe. Another section of the Sindi established themselves on the Taman peninsula, where they formed a ruling class over the indigenous Maeotians, the latter of whom were of native Caucasian origin.


title: Scythia

text: In West Asia, the Scythians would go on to ally with the superpower of the region, the Neo-Assyrian Empire, when their king Bartatua married the Assyrian princess Serua-eterat.


title: Scythia

text: Bartatua was succeeded by his son with Serua-eterat, Madyes, who in 653 BC invaded the Medes, thus starting a period which Herodotus of Halicarnassus called the "Scythian rule over Asia," after which he expanded the Scythian hegemony to the states of Mannae and Urartu, and entered Anatolia and defeated the Cimmerians. Scythian power in West Asia thus reached its peak under Madyes, with the territories ruled by the Scythians extending from the Halys river in Anatolia in the west to the Caspian Sea and the eastern borders of Media in the east, and from Transcaucasia in the north to the northern borders of the Neo-Assyrian Empire in the south.


title: Scythia

text: By the 620s BC, the Assyrian Empire began unravelling, and in 625 BC the Median king Cyaxares overthrew the Scythian yoke over the Medes by assassinating the Scythian leaders, including Madyes. The Scythians soon took advantage of the power vacuum created by the crumbling of the power of their former Assyrian allies to overrun the Levant and Palestine till the borders of Egypt, from where they turned back after the pharaoh Psamtik I met them and convinced them to turn back by offering them gifts; some Scythian stragglers looted the temple of ʿAštart in the city and their descendants were allegedly afflicted by the goddess with a "female disease," due to which they became a class of transvestite diviners called the (meaning "unmanly" in Scythian).


title: Scythia

text: The Scythians were finally expelled from West Asia by the Medes in the 600s BC, after which they retreated to the Pontic Steppe. Some splinter Scythian groups nevertheless remained in West Asia and settled in Transcaucasia, who by the middle of the 6th century BC had completely assimilated culturally and politically into Median society and no longer existed as a distinct group.


title: Scythia

text: After their expulsion from West Asia, and beginning in the later 7th and lasting throughout much of the 6th century BC, the majority of the Scythians migrated from Ciscaucasia into the Pontic Steppe, which became the centre of Scythian power. Although Herodotus of Halicarnassus claimed that the Scythians retreated into the northern Pontic region through Crimea, archaeological evidence instead suggests that the Royal Scythians migrated northwards into western Ciscaucasia, and from there into the country of those Scythians who had previously established themselves in the Pontic steppe. Some of the Scythian groups who had settled in the eastern Pontic steppe to the east of the Dnipro river were displaced by the arrival of the Royal Scythians from West Asia, and they moved north into the region of the forest-steppe zone, where they constituted the tribe of the Androphagi.


title: Scythia

text: During this early phase of the Pontic Scythian kingdom, the hold of the Royal Scythians on the western part of the steppe located to the west of the Dnipro was light, and they were largely satisfied with the tribute they levied on the sedentary agriculturist population of the region, while the tribe of the Aroteres, which consisted of a settled Thracian population over which ruled an Iranic Scythian ruling class, imported Greek pottery, jewellery and weapons in exchange of agricultural products, and in turn offered them in tribute to their Scythian overlords, although the country of the Alazones tribe appears to have become poorer during this time, in the early 6th century BC, when many of the rebuilt pre-Scythian settlements in their territory were destroyed by the Royal Scythians arriving from West Asia. In Crimea, the Royal Scythians took over most of the territory up to the Cimmerian Bosporus in the east. In western Ciscaucasia, where the Scythians were not large in number enough to spread throughout the region, they instead took over the steppe to the south of the Kuban river's middle course, where they reared large herds of horses. During this period, the tribe of the Royal Scythians would primarily bury their dead at the edges of the territories they occupied, especially in the western Cisaucasian region, instead of within the steppe region that was the centre of their kingdom; due to this, several Scythian kurgan were located in Ciscaucasia, with some of them being significantly wealthy and belonging to aristocrats or royalty, and the Royal Scythians' burials in the Kuban Steppe were the most lavish of all Scythian funerary monuments during the Early Scythian period. During the early 6th century BC, the some groups of Transcaucasian Scythians migrating northwards would arrive into the Pontic Steppe to reinforce the Royal Scythians who had already arrived there.


title: Scythia

text: Between 650 and 625 BC, the Pontic Scythians came into contact with the Greeks, who were starting to create colonies in the areas under Scythian rule, including on the island of Borysthenes, near Taganrog on Lake Maeotis, as well as more places, including Panticapaeum, Pontic Olbia, and Phanagoria and Hermonassa on the Taman peninsula; the Greeks carried out thriving commercial ties with the sedentary peoples of the forest steppe who lived to the north of the Scythians, with the large rivers of eastern Europe which flowed into the Black Sea forming the main access routes to these northern markets. This process put the Scythians into permanent contact with the Greeks, and the relations between the latter and the Greek colonies remained peaceful, although the Scythians might have destroyed Panticapaeum at some point in the middle of the 6th century BC. The territory around Pontic Olbia was under the direct rule of that city and was inhabited only by Greeks.


title: Scythia

text: Soon after, during the Early Scythian period itself, the centre of power of the Royal Scythians shifted from the eastern Pontic steppe to the north-west, in the country of the Aroteres tribe, where was located the main industrial centre of Scythia; during this period, the Royal Scythians buried their dead in the country of , which was located on the boundary of the steppe and the forest-steppe, and corresponded to the eastern part of the country of the Aroteres.


title: Scythia

text: During this period, the Scythians were ruled by a succession of kings whose names were recorded by Herodotus of Halicarnassus:


title: Scythia

text: At the time of Idanthyrsus, and possibly later, the Scythians were ruled by three kings, with Scopasis and Taxacis ruling alongside him.


title: Scythia

text: In 513 BC, the king Darius I of the Persian Achaemenid Empire, which had succeeded the Median, Lydian, Egyptian, and Neo-Babylonian empires which the Scythians had once interacted with, carried out a campaign against the Pontic Scythians, for unclear reasons. Darius's invasion was resisted by the Scythian king Idanthyrsus, who led the combined forces of the Scythians and their neighbouring peoples, and by the kings Skōpasis and Taxakis, with the Scythians refused to fight an open battle against the well-organised Achaemenid army, and instead resorting to partisan warfare and goading the Persian army deep into Scythian territory. The Persian army might have crossed the Don river and reached the territory of the Sauromatians, were Darius built fortifications, but resumed their pursuit when the Scythian forces returned. The results of this campaign were also unclear, with the Persian inscriptions themselves referring to the (the "Saka who dwell beyond the (Black) Sea"), that is to the Scythians, as having been conquered by Darius, while Greek authors instead claimed that Darius's campaign failed and from then onwards developed a tradition of idealising the Scythians as being invincible thanks to their nomadic lifestyle.


title: Scythia

text: Over the course of the late 6th century BC, the Scythians had progressively lost their territories in the Kuban region to another nomadic Iranian people, the Sauromatians, beginning with the territory to the east of the Laba river, and then the whole Kuban territory. By the end of the 6th century BC, the Scythians had lost their territories in the Kuban Steppe and had been forced to retreat into the Pontic Steppe, except for its westernmost part which included the Taman peninsula, where the Scythian Sindi tribe formed a ruling class over the native Maeotians, due to which this country was named Sindica. By the 5th century BC, Sindica was the only place in the Caucasus where the Scythian culture survived.


title: Scythia

text: After losing their territories in the Kuban Steppe in the late 6th century BC, the Scythians had being forced to retreat into the Pontic Steppe, and the Royal Scythians' centre of power within Scythia shifted to the south, in the region of the bend of the Dnipro, where the site of Kamianka became the principal industrial centre of Scythia, with the sedentary population of the city being largely metal-workers who smelted bog iron ores into iron that was made into tools, simple ornaments and weapons for the agricultural population of the Dnipro valley and of other regions of Scythia, and the city itself was the most prominent supplier of iron and bronze products to the nomadic Scythians; the city of Kamianka also became the capital of the Scythian kings, whose headquarters were located in the further fortified acropolis of the city. At the same time, a wave of Sauromatian nomads from the lower Volga steppe in the east immigrated into Scythia over the course of 550 and 500 BC and were absorbed by the Pontic Scythians with whom they mingled. A large number of settlements in the valleys of the steppe rivers being destroyed as a result of these various migratory movements. The retreat of the Scythians from the Kuban Steppe and the arrival of the Sauromatian immigrants into the Pontic steppe over the course of the late 6th to early 5th centuries BC caused significant material changes in the Scythian culture soon after the Persian campaign which are not attributable to a normal evolution of it, resulting in the sudden appearance within the lower Dnipro region of a fully formed Scythian culture with no local forerunners, and which included a notable increase in the number of Scythian funerary monuments.


title: Scythia

text: The Scythians underwent tribal unification and political consolidation in reaction to the Persian invasion, and they also became more active and aggressive around this time, possibly as a result of the arrival of these new nomadic elements, or out of necessity to resist Persian expansionism. This change manifested itself through the consolidation of the dominant position of the Royal Scythians over the other tribes within Scythia and through the Royal Scythians' hold on the western part of their realm to the west of the Dnipro, where lived the agriculturist populations, becoming heavier and more oppressive. Another result of the changes within Scythia during this period was increased Scythian expansionism: one of the target areas of Scythian expansionism was Thrace, where the Scythians seem to have established a permanent presence to the south of the Danube at an early point, with the Greek cities of Kallatis and Dionysupolis in the area corresponding to the present-day Dobruja both being surrounded by Scythian territory; and, in 496 or 495 BC, the Scythians raided the Thracian territories far to the south of the Danube till the Thracian Chersonese on the Hellespont, as an attempt to secure themselves from Persian encroachment. The emergence of the Thracian Odrysian kingdom during the 5th century BC soon blocked the Scythian advances in Thrace, and the Scythians established friendly contacts with the Odrysians, with the Danube river being set as the common border between the two kingdoms, and a daughter of the Odrysian founder king Tērēs I marrying the Scythian king Ariapeithes; these friendly relations also saw the Scythians and Thracians adopting aspects of each other's art and lifestyles.


title: Scythia

text: Names of kings who ruled over the Scythians the 5th century BC are known, although it is unknown whether these kings were ruling only the western regions of Scythia located between the Danube and Pontic Olbia or over all the Scythians:


title: Scythia

text: In the north and north-west, Scythian expansionism manifested itself through the destruction of the fortified settlements of the forest steppe and the subjugation of its population.


title: Scythia

text: In the south, the Scythians tried to impose their rule over the Greek colonies on the northern shores of the Black Sea: the Greek settlement of at Taganrog on the lower reaches of the Don river river, which was the only Greek colony in that area, had already been destroyed by the Scythians between 550 and 525 BC, and, owing to the Scythians' necessity to continue commerce with the Greeks, was replaced by a Scythian settlement at which became the principal trade station between the Greeks and the Scythians in this region.


title: Scythia

text: Although the relations between the Scythians and the Greek cities of the northern Pontic region had until then been largely peaceful and the cities previously had no defensive walls and possessed unfortified rural settlements in the area, new hostile relations developed between these two parties, and during the 490s BC fortifications were built in many Pontic Greek cities, whose were abandoned or destroyed, while burials of men killed by Scythian-type arrowheads appeared in their nekropoleis. Between 450 and 400 BC, Kerkinitis was paying tribute to the Scythians. The Scythians were eventually able to successfully impose their rule over the Greek colonies in the north-western Pontic shores and in western Crimea, including Niconium, Tyras, Pontic Olbia, and Kerkinitis.