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Topic Review

Fedora (Operating System)

Fedora is a Linux distribution developed by the community-supported Fedora Project which is sponsored primarily by Red Hat, a subsidiary of IBM, with additional support from other companies. Fedora contains software distributed under various free and open-source licenses and aims to be on the leading edge of free technologies. Fedora is the upstream source of the commercial Red Hat Enterprise Linux distribution and for CentOS. Fedora is a fork of Red Hat Linux since RHL was discontinued in 2003. Since the release of Fedora 30, five different editions are currently available: Workstation, focused on the personal computer, Server for servers, CoreOS, focused on cloud computing, Silverblue, focused on an immutable desktop specialized to container-based workflows and IoT, focused on IoT devices. (As of February 2016), Fedora has an estimated 1.2 million users, including Linus Torvalds ((As of May 2020)), creator of the Linux kernel.

6.6K
27 Oct 2022

Topic Review

Artificial Intelligence in Archaeology

Artificial Intelligence (AI), due to its increasingly powerful predictive capabilities, is showing an increasing trend in attracting widespread interest in many sciences. Archaeologists now can more fully exploit the knowledge from an extensive amount of archaeological data with the use of artificial intelligence in such a way as to make decisions related to appropriate strategies for the preservation and protection of archaeological elements, as well as to decide on the most ideal point excavation in a complex cultural landscape.

6.6K
30 Nov 2022

Topic Review

The Tirukkural (திருக்குறள், literally Sacred Verses), or shortly the Kural, is a classic Tamil language text consisting of 1,330 short couplets of seven words each, or Kurals. The text is divided into three books, each with aphoristic teachings on virtue (aram, dharma), wealth (porul, artha) and love (inbam, kama). Considered one of the greatest works on ethics and morality, it is known for its universality and secular nature. Its authorship is traditionally attributed to Valluvar, also known in full as Thiruvalluvar. The text has been dated variously from 300 BCE to 5th century CE. The traditional accounts describe it as the last work of the third Sangam, but linguistic analysis suggests a later date of 450 to 500 CE and that it was composed after the Sangam period. The Kural is traditionally praised with epithets and alternate titles such as "the Tamil Veda" and "the divine book." It emphasizes non-violence and moral vegetarianism as virtues for an individual.[a] In addition, it highlights truthfulness, self-restraint, gratitude, hospitality, kindness, goodness of wife, duty, giving, and so forth, besides covering a wide range of social and political topics such as king, ministers, taxes, justice, forts, war, greatness of army and soldier's honor, death sentence for the wicked, agriculture, education, abstinence from alcohol and intoxicants. It also includes chapters on friendship, love, sexual union, and domestic life. The Kural has been widely admired by scholars and influential leaders across the ethical, social, political, economical, religious, philosophical, and spiritual spheres over its history. These include Ilango Adigal, Kambar, Leo Tolstoy, Mahatma Gandhi, Albert Schweitzer, Constantius Joseph Beschi, Karl Graul, George Uglow Pope, Alexander Piatigorsky, and Yu Hsi. The text has been translated into at least 40 Indian and non-Indian languages. The Kural is considered a masterpiece and one of the most important texts of the Tamil Literature. The Tamil people and the government of Tamil Nadu have long celebrated and upheld the text with reverence.

6.6K
10 Oct 2022

Topic Review

Uterosacral Ligament

The uterosacral ligaments (USLs) are extraperitoneal structures that extend backward from the posterior surface of the cervix and upper vagina to the second-to-fourth sacral vertebrae, forming the lateral boundaries of the rectouterine and rectovaginal spaces. They are composed mainly of connective tissue along with vessels and splanchnic nerve fibers.

6.6K
08 Feb 2021

Topic Review

Cathode Ray Tube

The cathode ray tube (CRT) is a vacuum tube that contains one or more electron guns and a phosphorescent screen, and is used to display images. It modulates, accelerates, and deflects electron beam(s) onto the screen to create the images. The images may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets, or other phenomena. CRTs have also been used as memory devices, in which case the visible light emitted from the fluorescent material (if any) is not intended to have significant meaning to a visual observer (though the visible pattern on the tube face may cryptically represent the stored data). In television sets and computer monitors, the entire front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster. An image is produced by controlling the intensity of each of the three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference. In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is commonly used in oscilloscopes, a type of electronic test instrument. A CRT is constructed from a glass envelope which is large, deep (i.e., long from front screen face to rear end), fairly heavy, and relatively fragile. The interior of a CRT is evacuated to approximately 0.01 pascals (9.9×10−8 atm) to 133 nanopascals (1.31×10−12 atm), evacuation being necessary to facilitate the free flight of electrons from the gun(s) to the tube's face. The fact that it is evacuated makes handling an intact CRT potentially dangerous due to the risk of breaking the tube and causing a violent implosion that can hurl shards of glass at great velocity. As a matter of safety, the face is typically made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions, particularly if the CRT is used in a consumer product. Since the late 2000s, CRTs have been largely superseded by newer "flat panel" display technologies such as LCD, plasma display, and especially OLED displays, which in the case of LCD and OLED displays have lower manufacturing costs and power consumption, as well as significantly less weight and bulk. Flat panel displays can also be made in very large sizes; whereas 38 to 40 in (97 to 102 cm) was about the largest size of a CRT television, flat panels are available in 60 in (150 cm) and larger sizes.

6.6K
02 Dec 2022

Topic Review

Reverse Water Gas Shift Reaction

The catalytic conversion of CO2 to CO by the reverse water gas shift (RWGS) reaction followed by well-established synthesis gas conversion technologies could be a practical technique to convert CO2 to valuable chemicals and fuels in industrial settings. For catalyst developers, prevention of side reactions like methanation, low-temperature activity, and selectivity enhancements for the RWGS reaction are crucial concerns. Cerium oxide (ceria, CeO2) has received considerable attention due to its exceptional physical and chemical properties.

6.6K
09 Oct 2022

Topic Review

Convolutional Neural Network in the Medical Imaging

Convolutional Neural Networks (CNN), commonly known as ConvNet, is one of the common types of Artificial Neural Network (ANN) that comes under the supervised method category. This method is known for its ability to discover and interpret patterns. This pattern detection brings up the usefulness of CNN for image analysis.

6.6K
10 Apr 2023

Topic Review

Sea urchins (/ˈɜːrtʃɪnz/) are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone — from the intertidal seashore down to 5,000 metres (16,000 ft; 2,700 fathoms). The spherical, hard shells (tests) of sea urchins are round and spiny, ranging in diameter from 3 to 10 cm (1 to 4 in). Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (sessile) animals. In the food chain, the predators who eat sea urchins are the sea otter and the starfish, the wolf eel, the triggerfish, and human beings. Adult sea urchins have fivefold symmetry, but their pluteus larvae feature bilateral (mirror) symmetry, indicating that the sea urchin belongs to the Bilateria group of animal phyla, which also comprises the chordates and the arthropods, the annelids and the molluscs, and are found in every ocean and in every climate, from the tropics to the polar regions, and inhabit marine benthic (sea bed) habitats, from rocky shores to hadal zone depths. The fossil record of the Echinoids dates from the Ordovician period, some 450 million years ago; the closest echinoderm relatives of the sea urchin are the sea cucumbers (Holothuroidea); both are deuterostomes, a clade that includes the chordates. The animals have been studied since the 19th century as model organisms in developmental biology, as their embryos were easy to observe; this has continued with studies of their genomes because of their unusual fivefold symmetry and relationship to chordates. Species such as the slate pencil urchin are popular in aquariums, where they are useful for controlling algae. Fossil urchins have been used as protective amulets.

6.6K
19 Oct 2022

Topic Review

Word Lists by Frequency

Word lists by frequency are lists of a language's words grouped by frequency of occurrence within some given text corpus, either by levels or as a ranked list, serving the purpose of vocabulary acquisition. A word list by frequency "provides a rational basis for making sure that learners get the best return for their vocabulary learning effort" (Nation 1997), but is mainly intended for course writers, not directly for learners. Frequency lists are also made for lexicographical purposes, serving as a sort of checklist to ensure that common words are not left out. Some major pitfalls are the corpus content, the corpus register, and the definition of "word". While word counting is a thousand years old, with still gigantic analysis done by hand in the mid-20th century, natural language electronic processing of large corpora such as movie subtitles (SUBTLEX megastudy) has accelerated the research field. In computational linguistics, a frequency list is a sorted list of words (word types) together with their frequency, where frequency here usually means the number of occurrences in a given corpus, from which the rank can be derived as the position in the list.

6.6K
29 Nov 2022

Topic Review

Citrus limon (Lemon) Phenomenon

Citrus limon (lemon) is a species with valuable pharmaceutical, cosmetic and culinary (healthy food) properties. The valuable biological activity of C. limon is determined by its high content of phenolic compounds, mainly flavonoids (e.g., diosmin, hesperidin, limocitrin) and phenolic acids (e.g., ferulic, synapic, p-hydroxybenzoic acids). The essential oil is rich in bioactive monoterpenoids such as D-limonene, β-pinene, γ-terpinene. Recently scientifically proven therapeutic activities of C. limon include anti-inflammatory, antimicrobial, anticancer and antiparasitic activities. In view of beneficial properties C. limon is also used in the food industry and cosmetology. Attention should be pay on safety of use and potential phototoxicity of this raw materials.

6.6K
30 Oct 2020

Topic Review

Royal Marriages Act 1772

The Royal Marriages Act 1772 was an act of the Parliament of Great Britain which prescribed the conditions under which members of the British royal family could contract a valid marriage, in order to guard against marriages that could diminish the status of the royal house. The right of veto vested in the sovereign by this act provoked severe adverse criticism at the time of its passage. It was repealed as a result of the 2011 Perth Agreement, which came into force on 26 March 2015. Under the Succession to the Crown Act 2013, the first six people in the line of succession need permission to marry if they and their descendants are to remain in the line of succession.

6.6K
02 Nov 2022

Topic Review

Smart Waste Management and Classification Systems

Waste management requires necessary processes and activities to dominate from its inception to demolition. Waste comes in solid, liquid, or gaseous form, and every type of waste demands a different method of classification, disposal, and management. Waste management deals with every waste category, including household, organic, industrial, municipal, biomedical, organic, biological, and radioactive waste. Any unnecessary substance or substance with no use is called “waste”. Waste management involves the collection of the waste and its transport and disposal to appropriate locations. In the European Union (EUROPA), 423 million tons or 56% of domestic waste was recycled in 2016. Reports reflect the need for proper household waste management for the recycling process. Most of the Earth’s population will emigrate from rural to urban areas in the coming years. Therefore, bigger cities will require a highly sustainable infrastructure and smart waste management system to fulfill the fundamental needs of its citizens and provide them with a good service for the future.

6.6K
06 Sep 2022

Topic Review

In astronomy, a green star is a white or blueish star that appears greenish in some viewing conditions (see § Psychology below). Under typical viewing conditions, there are no greenish stars, because the color of a star is more or less given by a black-body spectrum. However, there are a few stars that appear greenish to some observers, due to the viewing conditions, for example the optical 'illusion' that a red object can make nearby objects look greenish (and vice versa). Some multiple star systems, such as Antares, have a bright reddish star where this contrast makes other stars in the system seem greenish.

6.6K
21 Nov 2022

Topic Review

Starship (Spacecraft)

Starship is the fully reusable second stage and space vehicle of the SpaceX BFR "Super Heavy" rocket currently under development by SpaceX. It is a long-duration cargo- and passenger-carrying spacecraft that also serves as the BFR launch vehicle second stage and integrated payload section. Three 9-meter (30 ft)-diameter stainless steel Starship test articles are being built, and one had already begun integrated system testing by March 2019. The Starship test flight rocket—Starhopper—will be used for initial integrated testing of the Raptor rocket engine with a flight-capable propellant structure as well as for low-altitude, low-velocity flight testing of launches and landings. It began hotfire testing in April 2019. Two additional test articles, Starship orbital prototypes, are being built by competing teams in South Texas and along the space coast of Florida. They are planned to be used after mid-2019 for high-altitude, high-velocity testing. Integrated system testing of Starhopper, including the first flight test, began in April 2019. SpaceX is planning to launch commercial payloads using Starship no earlier than 2021.

6.6K
21 Oct 2022

Topic Review

Supercritical Water Gasification (SCWG)

Gasification with supercritical water (SCWG) is a thermochemical process which, exploiting the properties of supercritical water (374.1 °C and 22.1 MPa ), allows to obtain a syngas rich in hydrogen. Both biomass and waste plastic can be used as feedstock.

6.6K
18 Sep 2020

Topic Review

Hindu Views on Monotheism

Hinduism incorporates diverse views on the concept of God. Different traditions of Hinduism have different theistic views, and these views have been described by scholars as polytheism, monotheism, henotheism, panentheism, pantheism, monism, agnostic, humanism, atheism or Nontheism. Monotheism is the belief in a single creator God and the lack of belief in any other Creator. Hinduism is not a monolithic faith and different sects may or may not posit or require such a belief. Religion is considered a personal belief in Hinduism and followers are free to choose the different interpretations within the framework of Karma and reincarnation. Many forms of Hinduism believe in a monotheistic God, such as Krishna followers, Vedanta, Arya samaj, Samkhya school of Vedas etc, Many traditions within Hinduism share the Vedic idea of a metaphysical ultimate reality and truth called Brahman instead. According to Jan Gonda, Brahman denoted the "power immanent in the sound, words, verses and formulas of Vedas" in the earliest Vedic texts. The early Vedic religious understanding of Brahman underwent a series of abstractions in the Hindu scriptures that followed the Vedic scriptures. These scriptures would reveal a vast body of insights into the nature of Brahman as originally revealed in the Vedas. These Hindu traditions that emerged from or identified with the Vedic scriptures and that maintained the notion of a metaphysical ultimate reality would identify that ultimate reality as Brahman. Hindu adherents to these traditions within Hinduism revere Hindu deities and, indeed, all of existence, as aspects of the Brahman. The deities in Hinduism are not considered to be almighty, omnipotent, omniscient and omnibenevolent, and spirituality is considered to be seeking the ultimate truth that is possible by a number of paths. Like other Indian religions, in Hinduism, deities are born, they live and they die in every kalpa (eon, cycle of existence). In Hindu philosophy, there are many different schools. Its non-theist traditions such as Samkhya, early Nyaya, Mimamsa and many within Vedanta such as Advaita do not posit the existence of an almighty, omnipotent, omniscient, omnibenevolent God (monotheistic God), while its theistic traditions posit a personal God left to the choice of the Hindu. The major schools of Hindu philosophy explain morality and the nature of existence through the karma and samsara doctrines, as in other Indian religions. Contemporary Hinduism can be categorized into four major traditions: Vaishnavism, Shaivism, Shaktism, and Smartism. Vaishnavism, Shaivism, and Shaktism worship Vishnu, Shiva, and Devi — the Divine Mother — as the Supreme respectively, or consider all Hindu deities as aspects of the formless Supreme Reality or Brahman. Other minor sects such as Ganapatya and Saura focus on Ganesha and Surya as the Supreme. A sub-tradition within the Vaishnavism school of Hinduism that is an exception is dualistic Dvaita, founded by Madhvacharya in the 13th-century (where Vishnu as Krishna is a monotheistic God). This tradition posits a concept of monotheistic God so similar to Christianity that Christian missionaries in colonial India suggested that Madhvacharya was likely influenced by early Christians who migrated to India, a theory that has been discredited by scholars. Furthermore, many adherents consider these similarities to be superficial and insubstantial; for example, Madhvacharya postulates three co-eternal fundamental realities, consisting of Supreme Being (Vishnu or paramathma), individual souls (jīvātman), and inanimate matter.

6.6K
15 Nov 2022

Topic Review

Different Types of Adipocytes

Adipose tissue resides in specific depots scattered in peripheral or deeper locations all over the body and it enwraps most of the organs. This tissue is always in a dynamic evolution as it must adapt to the metabolic demand and constraints. It exhibits also endocrine functions important to regulate energy homeostasis. This complex organ is composed of depots able to produce opposite functions to monitor energy: the so called white adipose tissue acts to store energy as triglycerides preventing ectopic fat deposition while the brown adipose depots dissipate it. It is composed of many cell types. Different types of adipocytes constitute the mature cells specialized to store or burn energy. Immature adipose progenitors (AP) presenting stem cells properties contribute not only to the maintenance but also to the expansion of this tissue as observed in overweight or obese individuals.

6.6K
28 Apr 2021

Topic Review

Role of Chloroplast Gene Expression

Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent. Here, we discuss the emerging roles of the distinct chloroplast gene expression processes in plant responses to environmental stresses. For example, the transcription and translation of psbA play an important role in high-light stress responses. A better understanding of the connection between chloroplast gene expression and environmental stress responses is crucial for breeding stress-tolerant crops better able to cope with the rapidly changing environment. Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent.

6.6K
02 Sep 2020

Topic Review

Visual Appearance of Oil

The visual appearance of oil spills at sea is often used as an indicator of spilled oil properties, state and slick thickness. These appearances and the oil properties that are associated with them are reviewed in this entry. The appearance of oil spills is an estimator of thickness of thin oil slicks, thinner than a rainbow sheen (<3 µm). Rainbow sheens have a strong physical explanation. Thicker oil slicks (e.g., >3 µm) are not correlated with a given oil appearance. At one time, the appearance of surface discharges from ships was thought to be correlated with discharge rate and vessel speed; however, this approach is now known to be incorrect. Oil on the sea can sometimes form water-in-oil emulsions, dependent on the properties of the oil, and these are often reddish in color. These can be detected visually, providing useful information on the state of the oil. Oil-in-water emulsions can be seen as a coffee-colored cloud below the water surface. Other information gleaned from the oil appearance includes coverage and distribution on the surface.

6.6K
27 Jan 2021

Topic Review

Transmission Dynamics of COVID-19

COVID-19 is pneumonia caused by a novel coronavirus which is an emerging infectious disease, and outbreaks in more than 200 countries around the world. Consequently, the spread principles and prevention and control measures of COVID-19 have become a global problem to be solved. Here, we pose a series of dynamical models to reveal the transmission mechanisms of COVID-19. Based on these mathematical models, data fitting and spread trend of COVID-19 are explored to show the propagation law between human populations. We hope that our work may provide some useful insights for effective control of the COVID-19.

6.6K
28 Oct 2020

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