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Topic Review
Vascular bundles
Vascular bundles play important roles in transporting nutrients, growth signals, amino acids, and proteins between aerial and underground tissues. 
  • 11.2K
  • 26 Feb 2021
Topic Review
List of ASTM International Standards (E)
This is a list of ASTM International standards for "Materials for Specific Applications".
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  • 30 Sep 2022
Topic Review
Gemini Surfactants
Gemini surfactants are dimeric structures, composed of two hydrophobic chains and two hydrophilic heads, linked by a spacer at or near the head groups. They present lower CMC, better efficiency to form micelles, and solubilization capacity comparedto their conventional (monomeric) counterparts. They can also reduce the surface tension of water and the oil–water interfacial tension from 10 to 100 times. This behaviour depends mainly on the nature of their components (heads, hydrophobic chains and spacer); thus, their synthesis is focused mainly on varying the type and length of these components.
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  • 21 Feb 2022
Topic Review
Surface Cleaning Methods
It is difficult to avoid surface contaminants in the processes of integrated circuit manufacturing, optical elements processing and additive forging. The presence of surface contaminants will bring great problems to above process. For example, in large- scale integrated circuits manufacturing, the submicron contaminants on silicon wafer surface will cause defects in the chip directly [1]. And in the manufacture of optical elements, the quality of the cleaned surface will directly affect the damage resistance of optical elements [2], and the presence of surface contaminants will affect its service life [3]. Similarly, during the additive forging process, the surface contaminants will affect the interface healing state of the substrate and ultimately affect its bonding performance. However, surface contaminants can be removed effectively by a suitable surface cleaning method, so surface cleaning is of great significance to solve the above problems.
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  • 29 Oct 2020
Topic Review
Timeline of Operating Systems
This article presents a timeline of events in the history of computer operating systems from 1951 to the current day. For a narrative explaining the overall developments, see the History of operating systems.
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  • 04 Nov 2022
Topic Review
Separatist Feminism
Separatist feminism is a form of radical feminism that holds that opposition to patriarchy is best done through focusing exclusively on women and girls. Some separatist feminists believe that men cannot make positive contributions to the feminist movement and that even well-intentioned men replicate the dynamics of patriarchy. Author Marilyn Frye describes separatist feminism as "separation of various sorts or modes from men and from institutions, relationships, roles and activities that are male-defined, male-dominated, and operating for the benefit of males and the maintenance of male privilege – this separation being initiated or maintained, at will, by women". In a tract on socialist feminism published in 1972, the Hyde Park Chapter of the Chicago Women's Liberation Union differentiated between separatism as an "ideological position" and as a "tactical position". In the same document, they further distinguished between separatism as "personal practice" and as "political position".
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  • 27 Oct 2022
Topic Review
Nutraceuticals
Nutraceuticals are essential food constituents that provide nutritional benefits as well as medicinal effects. The benefits of these foods are due to the presence of active compounds such as carotenoids, collagen hydrolysate, and dietary fibers.
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  • 18 May 2021
Topic Review
Southern European People
Southern European people are a pan-ethnic group, or multi-ethnic regional grouping, and the inhabitants of Southern Europe. South or Southern Europeans can usually trace back full or partial heritage to Greece, Italy, Spain , Portugal, as well as nations bordering with, or ethnoculturally related to, the region. As the pan-ethnic group is also culturally defined, rather than exclusively a geographical category, it often includes peoples inhabiting areas that are, at times, considered outside of the region. This can include people with heritage from Southern France, the Mediterranean islands of Corsica (also part of France ), Malta and Cyprus (geographically part of West Asia), Southeastern Europe's Albania and European Turkey. There are also descriptions of Southern Europeans which include ancestry from other nations in Southeast Europe, and countries of the South Slavs, particularly in diasporic identification. As Slavs, they are also often identified as Eastern Europeans. There is a large Southern European diaspora, with significant concentrations in the United Kingdom, North America (Southern European Americans and Canadians), and Southern European Australians in Oceania. Other subgroups of Europeans include Eastern European people and Northwestern European people.
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  • 29 Sep 2022
Topic Review
Protein dynamics
Protein dynamics is a highly complex phenomenon comprising numerous contributions from motions with different mechanisms of action and happening with diverse timescales and amplitudes that highly depend on the system and the local environment.
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  • 01 Nov 2020
Topic Review
Death Anxiety
Death anxiety is an unavoidable common phenomenon in our lives across cultures and religions. It is multidimensional and explained by different theoretical frameworks. Death anxiety can have negative impacts on wellbeing. Death is an inevitable experience that generates a reduced sense of safety and stronger fear (Alkozei et al. 2019). 
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  • 06 Feb 2021
Topic Review
Polanyi’s Paradox
Polanyi's paradox, named in honour of the British-Hungarian philosopher Michael Polanyi, is the theory that human knowledge of how the world functions and capability are, to a large extent, beyond our explicit understanding. The theory was articulated by Michael Polanyi in his book The Tacit Dimension in 1966, but it was economist David Autor that named it as Polanyi's paradox in his 2014 research paper on “Polanyi's Paradox and the Shape of Employment Growth”. Summarised in the slogan "We can know more than we can tell", Polanyi's paradox is mainly to explain the cognitive phenomenon that there exist many tasks which we, human beings, understand intuitively how to perform but cannot verbalize the rules or procedures behind it. This "self-ignorance" is common to many human activities, from driving a car in traffic to face recognition. As Polanyi argues, humans are relying on their tacit knowledge, which is difficult to adequately express by verbal means, when engaging these tasks. Polanyi's paradox has been widely considered a major obstacle in the fields of AI and automation, since the absence of consciously accessible knowledge creates tremendous difficulty in programming.
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  • 02 Nov 2022
Topic Review
Power (International Relations)
Power in international relations is defined in several different ways. Modern discourse generally speaks in terms of state power, indicating both economic and military power. Those states that have significant amounts of power within the international system are referred to as small powers, middle powers, regional powers, great powers, superpowers, or hegemons, although there is no commonly accepted standard for what defines a powerful state. NATO Quint, the G7, the BRICS nations and the G20 are seen by academics as forms of governments that exercise varying degrees of influence within the international system. Entities other than states can also be relevant in power acquisition in international relations. Such entities can include multilateral international organizations, military alliance organizations like NATO, multinational corporations like Wal-Mart, non-governmental organizations such as the Roman Catholic Church, or other institutions such as the Hanseatic League and technology companies like Facebook and Google.
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  • 11 Oct 2022
Topic Review
Geography of Middle-Earth
The geography of Middle-earth encompasses the physical, political, and moral geography of J. R. R. Tolkien's fictional world of Middle-earth, strictly a continent on the planet of Arda but widely taken to mean the physical world, and Eä, all of creation, as well as all of his writings about it. Arda was created as a flat world, incorporating a Western continent, Aman, which became the home of the godlike Valar, as well as Middle-earth. At the end of the First Age, the Western part of Middle-earth, Beleriand, was drowned in the War of Wrath. In the Second Age, a large island, Númenor, was created in the Great Sea, Belegaer, between Aman and Middle-earth; it was destroyed in a cataclysm at the end of the Second Age, in which Arda was remade as a spherical world, and Aman was removed so that Men could not reach it. In The Lord of the Rings, Middle-earth at the end of the Third Age is described as having free peoples, namely Men, Hobbits, Elves, and Dwarves in the West, opposed to peoples under the control of the Dark Lord Sauron in the East. Some commentators have seen this as implying a moral geography of Middle-earth.
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  • 25 Oct 2022
Topic Review
Urban Modelling
Urban Modelling is an approach to abstracting reality in an effort to demonstrate, classify and explain urban functions in a simplified manner.  There is a long history of modelling in urban studies.  Today's models have become more quantitative, computation, and require large data sets and intense computation due to the complex nature of modern cities. 
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  • 07 Jun 2021
Topic Review
Evolution of Elephants
Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are an informal grouping within the proboscidean family Elephantidae. Elephantidae is the only surviving family of proboscideans; extinct members include the mastodons. Elephantidae also contains several extinct groups, including the mammoths and straight-tusked elephants. African elephants have larger ears and concave backs, whereas Asian elephants have smaller ears, and convex or level backs. The distinctive features of all elephants include a long proboscis called a trunk, tusks, large ear flaps, massive legs, and tough but sensitive skin. The trunk is used for breathing, bringing food and water to the mouth, and grasping objects. Tusks, which are derived from the incisor teeth, serve both as weapons and as tools for moving objects and digging. The large ear flaps assist in maintaining a constant body temperature as well as in communication. The pillar-like legs carry their great weight. Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia and are found in different habitats, including savannahs, forests, deserts, and marshes. They are herbivorous, and they stay near water when it is accessible. They are considered to be keystone species, due to their impact on their environments. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. Females (cows) tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups, which do not include bulls, are usually led by the oldest cow, known as the matriarch. Males (bulls) leave their family groups when they reach puberty and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate. They enter a state of increased testosterone and aggression known as musth, which helps them gain dominance over other males as well as reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell, and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to have self-awareness, and appear to show empathy for dying and dead family members. African bush elephants and Asian elephants are listed as endangered and African forest elephants as critically endangered by the International Union for Conservation of Nature (IUCN). One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past, they were used in war; today, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature, and popular culture.
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  • 28 Nov 2022
Topic Review
Social Media in Speaking Skills
The ubiquitous nature of social media (SM) makes it a very essential tool to use in the world of education, especially with the advent of the COVID-19 pandemic which has led to a paradigm shift in the approaches used in the teaching and learning of English language skills. Findings reveal that there are improvements in speaking skills, as well as confidence to speak and a decline in speaking anxiety. Teachers and educators can now make use of the various social media platforms such as Telegram, Facebook, WhatsApp, and others to provide learners with more practice that is not only restricted to the classroom but has moved beyond it.
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  • 18 Nov 2021
Topic Review
A Strategic Information System Planning and Strategy-As-Practice Perspective
Strategic information system planning (SISP) is a central process that enables organizations to identify the strategic alignment of their IT portfolio to achieve their business needs and objectives. The extant SISP literature has focused on theoretical and processual aspects and has left methodological ambiguity about how SISP is practiced. Strategic information system planning (SISP) becomes central for any business when an organization faces an inflection point concerning its information system.
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  • 15 Jun 2022
Topic Review
Red Algae
Red algae, or Rhodophyta (/roʊˈdɒfɪtə/, /ˌroʊdəˈfaɪtə/; from grc ῥόδον (rhódon) 'rose', and φυτόν (phutón) 'plant'), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority of species (6,793) are found in the Florideophyceae (class), and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats but relatively rare in freshwaters. Approximately 5% of red algae species occur in freshwater, environments with greater concentrations found in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, there are no terrestrial species, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity. The red algae form a distinct group characterized by having eukaryotic cells without flagella and centrioles, chloroplasts that lack external endoplasmic reticulum and contain unstacked (stroma) thylakoids, and use phycobiliproteins as accessory pigments, which give them their red color. Red algae store sugars as floridean starch, which is a type of starch that consists of highly branched amylopectin without amylose, as food reserves outside their plastids. Most red algae are also multicellular, macroscopic, marine, and reproduce sexually. The red algal life history is typically an alternation of generations that may have three generations rather than two. The coralline algae, which secrete calcium carbonate and play a major role in building coral reefs, belong here. Red algae such as dulse (Palmaria palmata) and laver (nori/gim) are a traditional part of European and Asian cuisines and are used to make other products such as agar, carrageenans and other food additives.
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  • 11 Nov 2022
Topic Review
Incircle and Excircles of a Triangle
In geometry, the incircle or inscribed circle of a triangle is the largest circle contained in the triangle; it touches (is tangent to) the three sides. The center of the incircle is a triangle center called the triangle's incenter. An excircle or escribed circle of the triangle is a circle lying outside the triangle, tangent to one of its sides and tangent to the extensions of the other two. Every triangle has three distinct excircles, each tangent to one of the triangle's sides. The center of the incircle, called the incenter, can be found as the intersection of the three internal angle bisectors. The center of an excircle is the intersection of the internal bisector of one angle (at vertex [math]\displaystyle{ A }[/math], for example) and the external bisectors of the other two. The center of this excircle is called the excenter relative to the vertex [math]\displaystyle{ A }[/math], or the excenter of [math]\displaystyle{ A }[/math]. Because the internal bisector of an angle is perpendicular to its external bisector, it follows that the center of the incircle together with the three excircle centers form an orthocentric system.:p. 182 All regular polygons have incircles tangent to all sides, but not all polygons do; those that do are tangential polygons. 
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  • 11 Nov 2022
Topic Review
Mitsubishi Challenger
The Mitsubishi Challenger is a mid-size SUV produced by the Japanese manufacturer Mitsubishi Motors since 1996, spanning over three generations. Since 2015, for the third generation model, Mitsubishi has no longer used the Challenger name, but using the Pajero Sport/Montero Sport/Shogun Sport name instead.
  • 11.0K
  • 10 Oct 2022
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