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Topic Review
Free Society
The term free society is used frequently by American libertarian theorists to denote a society in which their ideal political, legal and economic aims are in effect. In a theoretical free society, all individuals act voluntarily, having the freedom to obtain the power and resources to fulfill their own potential. Adlai Stevenson defined free societies as a society in which individuals find it "safe to be unpopular". Others, such as Chandran Kukathas, described a free society as dependent upon the "principle of freedom of association". Cindy Cohn has argued that the freedom to have a "private conversation" is "central to a free society". These interpretations can also be elaborated in terms of freedom of speech – if people have a right to express their views without fear of arrest, imprisonment, or physical harm. In a free society, individuals would organize in voluntary associations, including free market and communal societies. Individuals would gain more prosperity due to the lack of restrictions on trade and wealth creation.
  • 8.3K
  • 11 Oct 2022
Topic Review
Theories of International Trade
Economists have developed theories explaining World Trade, which are called” theories of international trade”. Theories of international trade explain what exactly happens in international trade, such as mercantilist theory. This theory was popular in the sixteenth and eighteenth centuries. During that time, a nation’s wealth consisted only of gold or other types of precious metals, so theorists suggested that nations begin to accumulate more and more gold and other types of metals. 
  • 8.3K
  • 08 Jul 2022
Topic Review
Pollen Germination in Gymnosperms
Gymnosperms are amazing representatives of the flora. On the one hand, they are ancient plants with primitive characteristics of anatomical structure; on the other hand, they are perfectly adapted to their habitat and are the dominant species in many ecosystems due to their impressive size and longevity, with their reproductive system being of particular interest. It has progressive features, because in this group the reduced male gametophyte—pollen grain—first appeared, as well as the ability to form seeds. In addition, this group still represents a wide variety of reproductive patterns, strategies, and relationships. For example, the degree of gametophyte reduction varies, there are both zooidogamy and siphonogamy, and the reproductive process can both be relatively fast and last over several years.
  • 8.3K
  • 20 Jul 2021
Topic Review
Cultural Memory
Historic urban landscapes (HULs) are composed of layers of imbedded tangible and intangible features such as cultural memories. As the collective memories of city inhabitants, cultural memories can affect elements of social sustainability such as health, well-being, community identity, place perception and social engagement. This topic review points to the value of recalling cultural memory features in HULs, which can be used to achieve social sustainability.  In addition, it contributes to sustainable development through the contribution of cultural memory and its influence on the formation of place identity, sense of place, civic pride and quality of life in HULs. 
  • 8.3K
  • 27 Oct 2020
Topic Review
Social Complexity
Social complexity refers to the intricate and interconnected nature of social systems, where various elements such as institutions, individuals, and cultural dynamics interact in non-linear and unpredictable ways. It involves the recognition that social phenomena often exhibit emergent properties that cannot be fully understood by analyzing individual components in isolation, emphasizing the need for interdisciplinary approaches to grasp the complexity of social structures and behaviors.
  • 8.3K
  • 26 Jan 2024
Topic Review
Traditional Fermented Foods in Korea
Fermented foods are loved and enjoyed worldwide and are part of a tradition in several regions of the world. Koreans have traditionally had a healthy diet since people in this region have followed a fermented-foods diet for at least 5000 years. Fermented-product footprints are evolving beyond boundaries and taking the lead in the world of food. Fermented foods, such as jang (fermented soybean products), kimchi (fermented vegetables), jeotgal (fermented fish), and vinegar (liquor with grain and fruit fermentation), are prominent fermented foods in the Korean culture.
  • 8.3K
  • 09 Dec 2022
Topic Review
Matthews Correlation Coefficient
The Matthews correlation coefficient (MCC) or phi coefficient is used in machine learning as a measure of the quality of binary (two-class) classifications, introduced by biochemist Brian W. Matthews in 1975. The MCC is defined identically to Pearson's phi coefficient, introduced by Karl Pearson, also known as the Yule phi coefficient from its introduction by Udny Yule in 1912. Despite these antecedents which predate Matthews's use by several decades, the term MCC is widely used in the field of bioinformatics and machine learning. The coefficient takes into account true and false positives and negatives and is generally regarded as a balanced measure which can be used even if the classes are of very different sizes. The MCC is in essence a correlation coefficient between the observed and predicted binary classifications; it returns a value between −1 and +1. A coefficient of +1 represents a perfect prediction, 0 no better than random prediction and −1 indicates total disagreement between prediction and observation. However, if MCC equals neither −1, 0, or +1, it is not a reliable indicator of how similar a predictor is to random guessing because MCC is dependent on the dataset. MCC is closely related to the chi-square statistic for a 2×2 contingency table where n is the total number of observations. While there is no perfect way of describing the confusion matrix of true and false positives and negatives by a single number, the Matthews correlation coefficient is generally regarded as being one of the best such measures. Other measures, such as the proportion of correct predictions (also termed accuracy), are not useful when the two classes are of very different sizes. For example, assigning every object to the larger set achieves a high proportion of correct predictions, but is not generally a useful classification. The MCC can be calculated directly from the confusion matrix using the formula: In this equation, TP is the number of true positives, TN the number of true negatives, FP the number of false positives and FN the number of false negatives. If any of the four sums in the denominator is zero, the denominator can be arbitrarily set to one; this results in a Matthews correlation coefficient of zero, which can be shown to be the correct limiting value. The MCC can be calculated with the formula: using the positive predictive value, the true positive rate, the true negative rate, the negative predictive value, the false discovery rate, the false negative rate, the false positive rate, and the false omission rate. The original formula as given by Matthews was: This is equal to the formula given above. As a correlation coefficient, the Matthews correlation coefficient is the geometric mean of the regression coefficients of the problem and its dual. The component regression coefficients of the Matthews correlation coefficient are Markedness (Δp) and Youden's J statistic (Informedness or Δp'). Markedness and Informedness correspond to different directions of information flow and generalize Youden's J statistic, the [math]\displaystyle{ \delta }[/math]p statistics and (as their geometric mean) the Matthews Correlation Coefficient to more than two classes. Some scientists claim the Matthews correlation coefficient to be the most informative single score to establish the quality of a binary classifier prediction in a confusion matrix context.
  • 8.3K
  • 18 Nov 2022
Topic Review
Carbon Emission Efficiency
Carbon emission efficiency is an important concept in environmental science; it refers to the economic benefits generated by production activities that produce carbon emissions at the same time. The less carbon emissions generated per unit of economic output, the more carbon emission efficient it is.
  • 8.3K
  • 26 May 2022
Topic Review
Land Suitability Assessment
Land suitability assessment is a method of land evaluation, which identifies the major limiting factors for planting a particular crop. Land suitability assessment includes qualitative and quantitative evaluation. In the qualitative land suitability evaluations, information about climate, hydrology, topography, vegetation, and soil properties is considered and in quantitative assessment, the results are more detailed and yield is estimated. At present study we prepared land suitability assessment map for rain-fed wheat and barley crops based on FAO "land suitability assessment framework" using parametric method and machine learning algorithms in Kurdistan Province, located in west of Iran. This is a unique study that compared two machine learning-based and traditional-based approaches for mapping current and potential future land suitability classes. Moreover, potential yield of rain-fed wheat and barley crop were computed by FAO model.
  • 8.3K
  • 30 Oct 2020
Topic Review
Hauran
Hauran (Arabic: حوران / ALA-LC: Ḥawrān), also spelled Hawran, Houran and Horan, known to the Ancient Greeks and Romans as Auranitis, is a volcanic plateau, a geographic area and a people located in southwestern Syria and extending into the northwestern corner of Jordan, it’s known to be the birth place of the dabke dance which is the most popular dance in all of the Levant.
  • 8.3K
  • 10 Nov 2022
Topic Review
Ancient Egyptian Medicine
The medicine of the ancient Egyptians is some of the oldest documented. From the beginnings of the civilization in the late fourth millennium BC until the Persian invasion of 525 BC, Egyptian medical practice went largely unchanged and included simple non-invasive surgery, setting of bones, dentistry, and an extensive set of pharmacopoeia. Egyptian medical thought influenced later traditions, including the Greeks.
  • 8.3K
  • 20 Oct 2022
Topic Review Peer Reviewed
OAM of Light: Origins and Applications
Orbital Angular Momentum (OAM) of light is generating growing interest within the scientific community. This entry reviews the origins and applications of OAM. It is the counterpart of linear momentum for systems in rotation. The general expression of OAM is discussed, followed by its implications in terms of phase distribution and donut-shaped intensity profiles. Applications described include the generation of optical torque, telecommunications enhancement, and the rotational Doppler effect, emphasizing the role and consequences of angular momentum. In particular, its use to manipulate systems or to detect rotations is described. Finally, further developments and technological barriers are considered.
  • 8.3K
  • 17 Sep 2025
Topic Review
Red Supergiant Star
Red supergiants (RSGs) are stars with a supergiant luminosity class (Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars.
  • 8.3K
  • 18 Nov 2022
Topic Review
Triceratops
Triceratops (/traɪˈsɛrəˌtɒps/ trahy-ser-uh-tops; lit. three-horned face) is a genus of herbivorous chasmosaurine ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the Late Cretaceous period, about 68 million years ago in what is now North America. It is one of the last-known non-avian dinosaur genera, and became extinct in the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, which literally means 'three-horned face', is derived from the Greek words trí- (τρί-) meaning 'three', kéras (κέρας) meaning 'horn', and ṓps (ὤψ) meaning 'face'. Bearing a large bony frill, three horns on the skull, and a large four-legged body, exhibiting convergent evolution with rhinoceroses and bovines, Triceratops is one of the most recognizable of all dinosaurs and the most well-known ceratopsid. It was also one of the largest, up to 8–9 metres (26–30 ft) long and 5–9 metric tons (5.5–9.9 short tons) in body mass. It shared the landscape with and was most likely preyed upon by Tyrannosaurus, though it is less certain that two adults did battle in the fanciful manner often depicted in museum displays and popular images. The functions of the frills and three distinctive facial horns on its head have long inspired debate. Traditionally, these have been viewed as defensive weapons against predators. More recent interpretations find it probable that these features were primarily used in species identification, courtship, and dominance display, much like the antlers and horns of modern ungulates. Triceratops was traditionally placed within the "short-frilled" ceratopsids, but modern cladistic studies show it to be a member of the Chasmosaurinae which usually have long frills. Two species, T. horridus and T. prorsus, are considered valid today, from the seventeen species that have ever been named. Research published in 2010 concluded that the contemporaneous Torosaurus, a ceratopsid long regarded as a separate genus, represents Triceratops in its mature form. This view has been disputed; further data is needed to settle the debate. Triceratops has been documented by numerous remains collected since the genus was first described in 1889 by American paleontologist Othniel Charles Marsh. Specimens representing life stages from hatchling to adult have been found. As the archetypal ceratopsid, Triceratops is one of the most popular dinosaurs, and has been featured in film, postal stamps, and many other types of media.
  • 8.3K
  • 01 Nov 2022
Topic Review
Head-Up Display (Video Gaming)
In video gaming, the HUD (heads-up display) or status bar is the method by which information is visually relayed to the player as part of a game's user interface. It takes its name from the head-up displays used in modern aircraft. The HUD is frequently used to simultaneously display several pieces of information including the main character's health, items, and an indication of game progression (such as score or level).
  • 8.3K
  • 31 Oct 2022
Topic Review
The Sims 3 Stuff Packs
Stuff packs are minor expansion packs for The Sims 3 that add new items, clothing, and furniture to the game without implementing any significant changes to gameplay.
  • 8.3K
  • 11 Nov 2022
Topic Review
PSA XUD
The PSA XUD is a Diesel engine designed and built by PSA - Peugeot and Citroën. It is an Indirect injection (IDI) engine, that uses a version of the Ricardo Consulting Engineers Ricardo Comet V prechamber cylinder head design. The engine comes in 1.8 L (1,769 cc) N/A, 1.8 Turbo, 1.9 L (1,905 cc) N/A, Turbo, 2.1 12 valve N/A and Turbo and was the predecessor to the HDI range of engines. Early HDi Engines were a PSA design, later 16 valve engines were jointly developed with Ford.
  • 8.3K
  • 28 Oct 2022
Topic Review
Grinder (Biohacking)
Grinders are people who apply the hacker ethic to improve their own bodies with do it yourself cybernetic devices or introducing Biochemicals into the body to enhance or change their bodies' functionality. Many grinders identify with the biopunk movement, open-source transhumanism, and techno-progressivism. The Grinder movement is strongly associated with the body modification movement and practices actual implantation of cybernetic devices in organic bodies as a method of working towards transhumanism, such as designing and installing do-it-yourself body-enhancements such as magnetic implants. Biohacking emerged in a growing trend of non-institutional science and technology development. According to Biohack.me, "Grinders are passionate individuals who believe the tools and knowledge of science belong to everyone. Grinders practice functional extreme body modification in an effort to improve the human condition. [Grinders] hack [them]selves with electronic hardware to extend and improve human capacities. Grinders believe in action, [thei]r bodies the experiment." "Biohacking" can also refer to managing one's own biology using a combination of medical, nutritional and electronic techniques. This may include the use of nootropics, non-toxic substances, and/or cybernetic devices for recording biometric data (as in the Quantified Self movement).
  • 8.3K
  • 21 Nov 2022
Topic Review
Terminology of the British Isles
The terminology of the British Isles refers to the various words and phrases that are used to describe the different (and sometimes overlapping) geographical and political areas of the islands of Great Britain, Ireland, and the smaller islands which surround them. The terminology is often a source of confusion, partly owing to the similarity between some of the actual words used, but also because they are often used loosely. In addition, many of the words carry both geographical and political connotations which are affected by the history of the islands. The purpose of this article is to explain the meanings of and relationships among the terms in use; however many of these classifications are contentious and are the subject of disagreement (See the British Isles naming dispute).
  • 8.3K
  • 03 Nov 2022
Topic Review
Semaphore Telegraph
A semaphore telegraph is an early system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position. The most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. Lines of relay towers with a semaphore rig at the top were built within line-of-sight of each other, at separations of 5–20 miles (8.0–32.2 km). Operators at each tower would watch the neighboring tower through a spyglass, and when the semaphore arms began to move spelling out a message, they would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. Semaphore lines were a precursor of the electrical telegraph, which would replace them half a century later, and would also be cheaper, faster, and more private. The line-of-sight distance between relay stations was limited by geography and weather, and prevented the optical telegraph from crossing wide expanses of water, unless a convenient island could be used for a relay station. Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).
  • 8.3K
  • 28 Nov 2022
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