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Topic Review
Autonomous Spaceport Drone Ship
An autonomous spaceport drone ship (ASDS) is an ocean-going vessel derived from a deck barge, outfitted with station-keeping engines and a large landing platform. Construction of such ships was commissioned by aerospace company SpaceX to allow for recovery of rocket first-stages at sea for high-velocity missions which do not carry enough fuel to return to the launch site after lofting spacecraft onto an orbital trajectory. SpaceX has two operational drone ships and has a third under construction as of early 2018. Just Read the Instructions operates in the Pacific for launches from Vandenberg Air Force Base ; Of Course I Still Love You operates in the Atlantic for launches from Cape Canaveral. A Shortfall of Gravitas is under construction. (As of August 2018), 23 Falcon 9 flights have attempted to land on a drone ship, with 17 of them succeeding. The ASDS ships are a key component of the SpaceX reusable launch system development program which aims to significantly lower the price of space launch services through "full and rapid reusability." Any flights going to geostationary orbit or exceeding escape velocity will require landing at sea, encompassing about half of SpaceX missions.
  • 6.1K
  • 27 Oct 2022
Topic Review
Classification of the Approved EGFR-TKIs
Targeting EGFR with small-molecule inhibitors is a valid strategy in cancer therapy. Since the approval of the first EGFR-TKI in 2003, a huge number of EGFR inhibitors were reported. Classification of these inhibitors could help the researchers to understand their structure-activity relationship. Herein, we introduce different types of classifications of the EGFR-TKIs, which received global approval for clinical use. In the following, the EGFR-targeting drugs are classified based on their chemistry, clinical use, target kinases, and the type of inhibition/interaction with EGFR. 
  • 6.1K
  • 25 Nov 2021
Topic Review
Michael Addition of Carbonyl Compounds to α,β-Unsaturated Nitroalkenes
The proline-catalyzed asymmetric Michael addition reaction of acetaldehyde with α,β-unsaturated nitroalkenes as synthetically useful routes to β-substituted derivatives of γ-Aminobutyric acid (GABA).
  • 6.1K
  • 01 Jul 2022
Topic Review
Division of Labour
The division of labour is the separation of tasks in any economic system or organisation so that participants may specialise (specialisation). Individuals, organizations, and nations are endowed with or acquire specialised capabilities and either form combinations or trade to take advantage of the capabilities of others in addition to their own. Specialised capabilities may include equipment or natural resources as well as skills and training and combinations of such assets acting together are often important. For example, an individual may specialise by acquiring tools and the skills to use them effectively just as an organization may specialize by acquiring specialised equipment and hiring or training skilled operators. The division of labour is the motive for trade and the source of economic interdependence. Historically, an increasing division of labour is associated with the growth of total output and trade, the rise of capitalism, and the increasing complexity of industrialised processes. The concept and implementation of division of labour has been observed in ancient Sumerian (Mesopotamian) culture, where assignment of jobs in some cities coincided with an increase in trade and economic interdependence. Division of labour generally also increases both producer and individual worker productivity. After the Neolithic Revolution, pastoralism and agriculture led to more reliable and abundant food supplies, which increased the population and led to specialisation of labour, including new classes of artisans, warriors, and the development of elites. This specialistion was furthered by the process of industrialisation, and Industrial Revolution-era factories. Accordingly, many classical economists as well as some mechanical engineers such as Charles Babbage were proponents of division of labour. Also, having workers perform single or limited tasks eliminated the long training period required to train craftsmen, who were replaced with lesser paid but more productive unskilled workers.
  • 6.1K
  • 17 Oct 2022
Topic Review
Plant Nutrition for Human Health
Is there any relationship between plant nutrition and human health? The overall response to this question is very positive, and a strong relationship between the nutrition of plants and humans has been reported. The nutritional status of edible plants consumed by humans can have a negative or positive impact on human health.
  • 6.1K
  • 14 Jul 2022
Topic Review
Rock Art
The term ‘rock art’ defines non-utilitarian humanly made markings on natural rock surfaces, caused either by an additive (pictograms, made by the application of material) or a reductive process (petroglyphs, made by the removal of rock material). The former include rock paintings, pigment drawings, stencils, and beeswax figures; the latter term covers engravings, percussion petroglyphs, and finger flutings. Rock art occurs in nearly all countries. Its uneven distribution is attributable to differences in cultural conventions as well as a taphonomic attribute, i.e. a result of preservation bias. Prehistoric rock art represents by far the largest body of evidence we possess of humanity’s cultural, cognitive, and artistic beginnings. Through its relative permanence, it has profoundly influenced the beliefs and cultural conventions of subsequent societies up to the present. It is, therefore, an integral part of humanity's collective memory and the most significant surviving witness of our cultural evolution. 
  • 6.1K
  • 07 Apr 2021
Topic Review
Floating Wind Turbines
Globally, the wind resource in deep water (depths > 60 m) is very abundant. Due to the abundance of potential at these depths, the wind turbines will need the design of a floating platform because the wind turbines that are currently in operation are mostly fixed at the bottom and are dependent upon conventional concrete with a gravity base that is not feasible at these depths. A balance among the two varying principles (i.e., the requirement for a stable foundation for the wind turbine’s control and operation and the nature of the substructure being innate, to respond to environmental forces) is required for the design of the floating platform for wind energy. The absence of rigid foundations results in an additional six degrees of freedom (DOFs) for the platform of floating turbines; three translational (surge X, sway Y, and heave Z) and three rotational (roll RotX, pitch RotY, and yaw RotZ). For the platforms of onshore wind turbines and bottom-mounted offshore wind turbines, the effect of soil-structure interaction (SSI) can be modeled with six degrees of freedom; three translational (horizontal forces in X and Y and vertical force in Z) and three rotational (rocking moments in X and Y and a torsional moment in Z) respectively.
  • 6.1K
  • 11 Oct 2021
Topic Review
Biocoagulant/bioflocculant application for drinking water
The utilization of metal-based conventional coagulants/flocculants to remove suspended solids from drinking water and wastewater is currently leading to new concerns. Alarming issues related to the prolonged effects on human health and further pollution to aquatic environments from the generated nonbiodegradable sludge are becoming trending topics. The utilization of biocoagulants/bioflocculants does not produce chemical residue in the effluent and creates nonharmful, biodegradable sludge.
  • 6.0K
  • 25 Dec 2020
Topic Review
Ivermectin during the COVID-19 Pandemic
Ivermectin (IVM) is a broad-spectrum antiparasitic agent, developed and funded by Merck & Co. in 1974 to control and eradicate onchocerciasis caused by the parasitic worm Onchocerca volvulus in West Africa, which in the 1980s infected approximately 340,000 people. At the time, Africa did not have the resources necessary to seek treatments for this condition. The avermectins, of which IVM is a member, were discovered by Professor Satoshi Ōmura as fermentation products of the bacterium Streptomyces avermitilis at the Kitasato Institute in Tokyo. For this discovery, he received the 2015 Nobel Prize in Physiology and Medicine, which he shared with William Campbell. IVM is used to treat onchocerciasis, lymphatic filariasis, strongyloidiasis and scabies, and, very recently, has been used to combat lice. The drug’s low cost, high efficacy, safety, and marked tropism for helminths, as well as the fact that it has almost no impact on human biochemistry, have led to the inclusion of IVM in the twentieth list of essential medicines and sixth list of vital medicines in children, a recommendation made by the expert committee of the World Health Organization (WHO) in 2019. The safety profile is attributed to its selective affinity for ion channels.
  • 6.0K
  • 22 Sep 2022
Topic Review
Tobacco Products
Tobacco is the agricultural product of the leaves of plants in the genus Nicotiana. All species of Nicotiana contain the addictive drug nicotine—a stimulant and sedative contained in all parts of the plants except the seeds—which occurs in varying amounts depending on the species and variety cultivated. See types of tobacco and curing of tobacco for more information. The vast majority of commercially available tobacco is derived from the species Nicotiana tabacum, although it is also produced from Nicotiana alata, and to a lesser extent Nicotiana clevelandii, Nicotiana longiflora, and Nicotiana rustica, among others. N. rustica in particular contains much more nicotine than N. tabacum and other species of Nicotiana, and forms the basis of a number of unique tobacco products, including several preparations used in Latin American shamanic ceremonies. Once tobacco has been grown, harvested, cured, and processed, it is used to produce a number of different products. These are most often consumable; however, tobacco and the nicotine derived from it are also used to create pesticides. Tobacco products can generally be divided into two types: smoked tobacco (see tobacco smoking) and smokeless tobacco. An expert in tobacco and tobacco products — especially pipes, pipe tobacco, and cigars—including their procurement and sale, is called a tobacconist. The health effects of tobacco consumption are discussed in health effects of tobacco.
  • 6.0K
  • 19 Oct 2022
Topic Review
Diarchy
A diarchy (from Greek δι-, di-, "double", and -αρχία, -arkhía, "ruled")[note 1] or duumvirate (from Latin duumvirātus, "the office of the two men")[note 2] is a form of government characterized by corule, with two people ruling a polity together either lawfully or de facto, by collusion and force. The leaders of such a system are usually known as corulers. Historically, diarchy particularly referred to the system of shared rule in British India established by the Government of India Acts 1919 and 1935, which devolved some powers to local councils, which had included native Indian representation under the Indian Councils Act 1892. 'Duumvirate' principally referred to the offices of the various duumviri established by the Roman Republic. Both, along with less common synonyms such as biarchy and tandemocracy,[note 3] are now used more generally to refer to any system of joint rule or office. A monarchy temporarily controlled by two or more people is, however, usually distinguished as a coregency. Corule is one of the oldest forms of government. Historical examples include the Pandyan dynasty of Tamilakam, Sparta's joint kingdom, the Roman Republic's consuls, Carthage's Judges, and several ancient Polynesian societies. Systems of inheritance that often led to corule in Germanic and Dacian monarchies may be included as well, as may the dual occupants of the ranks of the Inca Empire. Modern examples of diarchies are Andorra, whose princes are the President of France and the Bishop of Urgell in Catalonia; and San Marino, whose republic is led by two Captains Regent.
  • 6.0K
  • 14 Nov 2022
Topic Review
Organ
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system. An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that makes the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the connective tissues that provide a suitable place for it to be situated and anchored. The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Organs exist in most multicellular organisms. In single-celled organisms such as bacteria, the functional analogue of an organ is known as an organelle. In plants, there are three main organs. In the study of anatomy, viscera (singular viscus) refers to the internal organs of the abdominal, thoracic, and pelvic cavities. The abdominal organs may be classified as solid organs, or hollow organs. The solid organs are the liver, pancreas, spleen, kidneys, and adrenal glands. The hollow organs of the abdomen are the stomach, intestines, gallbladder, bladder, and rectum. In the thoracic cavity the heart is a hollow, muscular organ. The number of organs in any organism depends on the definition used. By one widely adopted definition, 79 organs have been identified in the human body.
  • 6.0K
  • 14 Oct 2022
Topic Review
N1 (Rocket)
The N1/L3 (from Ракета-носитель Raketa-nositel', "Carrier Rocket"; Cyrillic: Н1) was a super heavy-lift launch vehicle intended to deliver payloads beyond low Earth orbit. The N1 was the Soviet counterpart to the US Saturn V and was intended to enable crewed travel to the Moon and beyond, with studies beginning as early as 1959. Its first stage, Block A, remains the most powerful rocket stage ever flown. However, all four first stages flown failed mid-flight because a lack of static test firings meant that plumbing issues and other adverse characteristics with the large cluster of thirty engines and its complex fuel and oxidizer feeder system were not revealed earlier in development. The N1-L3 version was designed to compete with the United States Apollo program to land a person on the Moon, using a similar lunar orbit rendezvous method. The basic N1 launch vehicle had three stages, which were to carry the L3 lunar payload into low Earth orbit with two cosmonauts. The L3 contained one stage for trans-lunar injection; another stage used for mid-course corrections, lunar orbit insertion, and the first part of the descent to the lunar surface; a single-pilot LK Lander spacecraft; and a two-pilot Soyuz 7K-LOK lunar orbital spacecraft for return to Earth. The N1-L3 was underfunded and rushed, starting development in October 1965, almost four years after the Saturn V. The project was badly derailed by the death of its chief designer Sergei Korolev in 1966. Each of the four attempts to launch an N1 failed, with the second attempt resulting in the vehicle crashing back onto its launch pad shortly after liftoff. The N1 program was suspended in 1974, and officially canceled in 1976. All details of the Soviet crewed lunar programs were kept secret until the USSR was nearing collapse in 1989.
  • 6.0K
  • 30 Nov 2022
Topic Review
Metabolic N-Dealkylation and N-Oxidation
Metabolic reactions that occur at alkylamino moieties may provide insight into the roles of these moieties when they are parts of drug molecules that act at different receptors. N-dealkylation of N,N-dialkylamino moieties has been associated with retaining, attenuation or loss of pharmacologic activities of metabolites compared to their parent drugs. Further, N-dealkylation has resulted in clinically used drugs, activation of prodrugs, change of receptor selectivity, and providing potential for developing fully-fledged drugs.
  • 6.0K
  • 13 Apr 2021
Topic Review
Trickster
In mythology, and in the study of folklore and religion, a trickster is a character in a story (god, goddess, spirit, human, or anthropomorphisation), which exhibits a great degree of intellect or secret knowledge, and uses it to play tricks or otherwise disobey normal rules and conventional behaviour.
  • 6.0K
  • 03 Nov 2022
Topic Review
Communalism
Communalism usually refers to a system that integrates communal ownership and federations of highly localized independent communities. A prominent libertarian socialist, Murray Bookchin, defines the Communalism political philosophy that he developed as "a theory of government or a system of government in which independent communes participate in a federation", as well as "the principles and practice of communal ownership". The term 'government' in this case does not imply an acceptance of a State or top-down hierarchy. This usage of communalism appears to have emerged during the late 20th century to distinguish commune-based systems from other political movements and/or governments espousing (if not actually practicing) similar ideas. In particular, earlier communities and movements advocating such practices were often described as "anarchist", "socialist" and/or "communist". Many historical communities practicing utopian socialism or anarcho-communism did implement internal rules of communalist property ownership in the context of federated communalism. It is at least theoretically possible for a federation of communes to include communes which do not practice communalist rules of property, which is to say, that the overall national government may be a federation of communes, but that private property rather than communalist property is the order within each such commune. Karl Marx, often viewed as the founder of modern communism, criticized older forms, including primitive communism and/or utopian socialism, as poorly conceived and/or prone to disintegration in practice. Communalism in the form described above is distinct from the predominant usage in South Asian forms of English: allegiance to a particular ethnic and/or religious group rather than to a broader society. As such, this usage is synonymous with sectarianism and associated with communal violence.
  • 6.0K
  • 16 Nov 2022
Topic Review
Child Psychopathology
Child psychopathology refers to the scientific study of mental disorders in children and adolescents. Oppositional defiant disorder, attention-deficit hyperactivity disorder, and autism spectrum disorder are examples of psychopathology that are typically first diagnosed during childhood. Mental health providers who work with children and adolescents are informed by research in developmental psychology, clinical child psychology, and family systems. Lists of child and adult mental disorders can be found in the International Statistical Classification of Diseases and Related Health Problems, 10th Edition (ICD-10), published by the World Health Organization (WHO) and in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), published by the American Psychiatric Association (APA). In addition, the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood (DC: 0-3R) is used in assessing mental health and developmental disorders in children up to age five.
  • 6.0K
  • 11 Oct 2022
Topic Review
Proportional Representation
Proportional representation (PR) characterizes electoral systems in which divisions in an electorate are reflected proportionately in the elected body. The concept applies mainly to geographical and political divisions of the electorate. The essence of such systems is that all votes contribute to the result—not just a plurality, or a bare majority. The most prevalent forms of proportional representation all require the use of multiple-member voting districts (also called super-districts), as it is not possible to fill a single seat in a proportional manner. In fact, PR systems that achieve the highest levels of proportionality tend to include districts with large numbers of seats, as large as a province or an entire nation. The most widely used families of PR electoral systems are party-list PR, single transferable vote (STV), and mixed-member PR (MMP). In the European Parliament for instance, each member state has a number of seats that is (roughly) proportional to its population, enabling geographical proportional representation. Almost all European countries also have political proportional representation (ideological proportional representation to the degree that parties honestly describe their goals): When n% of the electorate support a particular political party or set of candidates as their favorite, then roughly n% of seats are allotted to that party or those candidates. According to the ACE Electoral Knowledge Network, some form of proportional representation is used for national lower house elections in 94 countries. Party list PR, being used in 85 countries, is the most widely used. MMP is used in seven lower houses. STV is used in only two: Ireland, since independence in 1922, and Malta, since 1921. STV is also used in the Australian Senate, and can be used for nonpartisan elections such as the city council of Cambridge MA. Due to factors such as electoral thresholds and the use of small constituencies, as well as manipulation tactics such as party splitting and gerrymandering, perfect proportionality is rarely achieved under these systems. Nonetheless, they approximate proportionality much better than other systems. Some jurisdictions use leveling seats to compensate for such factors.
  • 6.0K
  • 14 Oct 2022
Topic Review
Diagnosis and Management of Onychotillomania
Onychotillomania is defined as repetitive picking or pulling of the nail unit, causing damage to the nail matrix, nail bed, nail plate and/or periungual skin.
  • 6.0K
  • 23 Mar 2022
Topic Review
2015–16 Chinese Stock Market Turbulence
The Chinese stock market turbulence began with the popping of the stock market bubble on 12 June 2015 and ended in early February 2016. A third of the value of A-shares on the Shanghai Stock Exchange was lost within one month of the event. Major aftershocks occurred around 27 July and 24 August's "Black Monday". By 8–9 July 2015, the Shanghai stock market had fallen 30 percent over three weeks as 1,400 companies, or more than half listed, filed for a trading halt in an attempt to prevent further losses. Values of Chinese stock markets continued to drop despite efforts by the government to reduce the fall. After three stable weeks the Shanghai index fell again on 24 August by 8.48 percent, marking the largest fall since 2007. At the October 2015 International Monetary Fund (IMF) annual meeting of "finance ministers and central bankers from the Washington-based lender’s 188 member-countries" held in Peru, China's slump dominated discussions with participants asking if "China’s economic downturn [would] trigger a new financial crisis". By the end of December 2015 China's stock market had recovered from the shocks and had outperformed S&P for 2015, though still well below the 12 June highs. By the end of 2015 the Shanghai Composite Index was up 12.6 percent. In January 2016 the Chinese stock market experienced a steep sell-off and trading was halted on 4 and 7 January 2016 after the market fell 7%, the latter within 30 minutes of open. The market meltdown set off a global rout in early 2016. According to 19 January 2016 articles in the Xinhua News Agency, the official press agency of the China , China reported a 6.9 percent GDP growth rate for 2015 and an "economic volume of over ten trillion U.S. dollars". Forbes journalist argues that the "stock market crash does not indicate a blowout of the Chinese physical economy." China is shifting from a focus on manufacturing to service industries and while it has slowed down, it is still growing by 5%. After this last turbulence, as of January 2017 the Shanghai Composite Index has been stable around 3,000 points, 50% less than before the bubble popped.
  • 6.0K
  • 28 Nov 2022
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