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Topic Review
AK-630
The AK-630 is a Soviet and Russian fully automatic naval close-in weapon system based on a six-barreled 30 mm rotary cannon. In "630", "6" means 6 barrels and "30" means 30 mm. It is mounted in an enclosed automatic turret and directed by MR-123 radar and television detection and tracking. The system's primary purpose is defense against anti-ship missiles and other precision guided weapons. However it can also be employed against fixed or rotary wing aircraft, ships and other small craft, coastal targets, and floating mines. Once operational, this weapon system was rapidly adopted, with up to 8 units installed in every new Soviet warship (from mine-hunters to aircraft carriers), and hundreds produced in total.
  • 7.0K
  • 08 Oct 2022
Topic Review
US Airways Livery
US Airways' aircraft livery has varied both under the US Airways and USAir name. In general the Express and Shuttle divisions have had liveries that closely parallel the company-wide livery at the time. The US Airways livery has been replaced with the new American Airlines livery, in accordance with their merger.
  • 7.0K
  • 16 Nov 2022
Topic Review
Monogamy
Monogamy (/məˈnɒɡəmi/ mə-NOG-ə-mee) is a form of dyadic relationship in which an individual has only one partner during their lifetime—alternately, only one partner at any one time (serial monogamy)—as compared to non-monogamy (e.g., polygamy or polyamory). The term is also applied to the social behavior of some animals, referring to the state of having only one mate at any one time.
  • 7.0K
  • 02 Nov 2022
Topic Review
Hybrid
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering times, pollen vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and the structure of the chromosomes. A few animal species and many plant species, however, are the result of hybrid speciation, including important crop plants such as wheat, where the number of chromosomes has been doubled. Human impact on the environment has resulted in an increase in the interbreeding between regional species, and the proliferation of introduced species worldwide has also resulted in an increase in hybridisation. This genetic mixing may threaten many species with extinction, while genetic erosion from monoculture in crop plants may be damaging the gene pools of many species for future breeding. A form of often intentional human-mediated hybridisation is the crossing of wild and domesticated species. This is common in both traditional horticulture and modern agriculture; many commercially useful fruits, flowers, garden herbs, and trees have been produced by hybridisation. One such flower, Oenothera lamarckiana, was central to early genetics research into mutationism and polyploidy. It is also more occasionally done in the livestock and pet trades; some well-known wild × domestic hybrids are beefalo and wolfdogs. Human selective breeding of domesticated animals and plants has resulted in the development of distinct breeds (usually called cultivars in reference to plants); crossbreeds between them (without any wild stock) are sometimes also imprecisely referred to as "hybrids". Hybrid humans existed in prehistory. For example, Neanderthals and anatomically modern humans are thought to have interbred as recently as 40,000 years ago. Mythological hybrids appear in human culture in forms as diverse as the Minotaur, blends of animals, humans and mythical beasts such as centaurs and sphinxes, and the Nephilim of the Biblical apocrypha described as the wicked sons of fallen angels and attractive women.
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  • 24 Nov 2022
Topic Review
May 20: Vasco da Gama Reaches India
Vasco da Gama’s arrival in Calicut, India on May 20, 1498, marked the first time a European reached India by sea, successfully navigating around the Cape of Good Hope and across the Indian Ocean. This event opened a direct maritime trade route between Europe and Asia, breaking the centuries-old overland monopoly held by Middle Eastern and Venetian traders. It initiated an era of European exploration, imperial expansion, and global maritime dominance, especially for Portugal.
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  • 20 May 2025
Topic Review
Bilaminar Blastocyst
Bilaminar blastocyst or bilaminar disc refers to the epiblast and the hypoblast, evolved from the embryoblast. These two layers are sandwiched between two balloons: the primitive yolk sac and the amniotic cavity. The inner cell mass, the embryoblast, begins to transform into two distinct epithelial layers just before implantation occurs. The epiblast is the outer layer that consists of columnar cells. The inner layer is called the hypoblast, or primitive endoderm, which is composed of cuboidal cells. As the two layers become evident, a basement membrane presents itself between the layers. The final two layers of the embryoblast are known collectively as the bilaminar embryonic disc as well as the bilaminar blastocyst or bilaminar blastoderm. This bilaminar blastocyst also defines the primitive dorsal ventral axis. Blastocyst implantation will occur during the second week of fetal development in the endometrium of the uterus; the epiblast is dorsal and the hypoblast is ventral.
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  • 19 May 2023
Topic Review
Philosophy of Max Stirner
The philosophy of Max Stirner is credited as a major influence in the development of individualism, nihilism, existentialism, post-modernism and anarchism (especially of egoist anarchism, individualist anarchism, postanarchism and post-left anarchy). Max Stirner's main philosophical work was The Ego and Its Own, also known as The Ego and His Own (Der Einzige und sein Eigentum in German, or more accurately The Individual and its Property). Stirner's philosophy has been cited as an influence on both his contemporaries, most notably Karl Marx (who was strongly opposed to Stirner's views) as well as subsequent thinkers such as Friedrich Nietzsche, Enrico Arrigoni, Steven T. Byington, Benjamin Tucker, Émile Armand and Albert Camus
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  • 21 Oct 2022
Topic Review
Urban Legend
An urban legend, urban myth, urban tale, or contemporary legend is a genre of folklore comprising stories circulated as true, especially as having happened to a friend or family member, often with horrifying or humorous elements. These legends can be entertainment, but often concern mysterious peril or troubling events, such as disappearances and strange objects. They may also be confirmation of moral standards, or reflect prejudices, or be a way to make sense of societal anxieties. Urban legends are most often circulated orally, but can be spread by any media, including newspapers, e-mail and social media. Some urban legends have passed through the years with only minor changes to suit regional variations. Recent legends tend to reflect modern circumstances: for instance, the common legend of a person being ambushed and anesthetized, only to wake up and realize that they are now missing a kidney that was supposedly surgically removed for transplantation.
  • 7.0K
  • 04 Oct 2022
Topic Review
Elephant
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.
  • 7.0K
  • 09 Nov 2022
Topic Review
Construction 4.0
Construction 4.0 is a variety of interdisciplinary technologies, methodologies and concepts that digitize, automate and integrate the construction process at all stages of the value chain
  • 7.0K
  • 27 Mar 2023
Topic Review
Transmission Electron Microscopy
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device. Transmission electron microscopes are capable of imaging at a significantly higher resolution than light microscopes, owing to the smaller de Broglie wavelength of electrons. This enables the instrument to capture fine detail—even as small as a single column of atoms, which is thousands of times smaller than a resolvable object seen in a light microscope. Transmission electron microscopy is a major analytical method in the physical, chemical and biological sciences. TEMs find application in cancer research, virology, and materials science as well as pollution, nanotechnology and semiconductor research, but also in other fields such as paleontology and palynology. TEM instruments have multiple operating modes including conventional imaging, scanning TEM imaging (STEM), diffraction, spectroscopy, and combinations of these. Even within conventional imaging, there are many fundamentally different ways that contrast is produced, called "image contrast mechanisms". Contrast can arise from position-to-position differences in the thickness or density ("mass-thickness contrast"), atomic number ("Z contrast", referring to the common abbreviation Z for atomic number), crystal structure or orientation ("crystallographic contrast" or "diffraction contrast"), the slight quantum-mechanical phase shifts that individual atoms produce in electrons that pass through them ("phase contrast"), the energy lost by electrons on passing through the sample ("spectrum imaging") and more. Each mechanism tells the user a different kind of information, depending not only on the contrast mechanism but on how the microscope is used—the settings of lenses, apertures, and detectors. What this means is that a TEM is capable of returning an extraordinary variety of nanometer- and atomic-resolution information, in ideal cases revealing not only where all the atoms are but what kinds of atoms they are and how they are bonded to each other. For this reason TEM is regarded as an essential tool for nanoscience in both biological and materials fields. The first TEM was demonstrated by Max Knoll and Ernst Ruska in 1931, with this group developing the first TEM with resolution greater than that of light in 1933 and the first commercial TEM in 1939. In 1986, Ruska was awarded the Nobel Prize in physics for the development of transmission electron microscopy.
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  • 05 Dec 2022
Topic Review
Wife-carrying
Wife carrying (Finnish: eukonkanto or akankanto, Estonian: naisekandmine, Swedish: kärringkånk) is a contest in which male competitors race while each carrying a female teammate. The objective is for the male to carry the female through a special obstacle track in the fastest time. The sport was first introduced at Sonkajärvi, Finland . Several types of carrying may be practised: either a classic piggyback, a fireman's carry (over the shoulder), or Estonian-style (wife upside-down on his back with her legs over the neck and shoulders).
  • 7.0K
  • 11 Oct 2022
Topic Review
Aesthetics
Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed through judgments of taste. Aesthetics covers both natural and artificial sources of experiences and how we form a judgment about those sources. It considers what happens in our minds when we engage with objects or environments such as viewing visual art, listening to music, reading poetry, experiencing a play, watching a fashion show, movie, sports or even exploring various aspects of nature. The philosophy of art specifically studies how artists imagine, create, and perform works of art, as well as how people use, enjoy, and criticize art. Aesthetics considers why people like some works of art and not others, as well as how art can affect moods or even our beliefs. Both aesthetics and the philosophy of art ask questions like "What is art?," "What is a work of art?," and "What makes good art?" Scholars in the field have defined aesthetics as "critical reflection on art, culture and nature". In modern English, the term "aesthetic" can also refer to a set of principles underlying the works of a particular art movement or theory (one speaks, for example, of a Renaissance aesthetic).
  • 7.0K
  • 04 Nov 2022
Topic Review
Nanocarriers
Nanocarriers are added as colloidal nanosystems loaded with therapeutic agents (anticancer agents or any macromolecules, such as proteins or genes), which allow drugs to selectively accumulate at the site of cancerous tumors. As a result of their unique nanometer range, 1–1000 nm (drug administration is preferable in the 5–200 nm range), they are used for cancer treatment. The main and most promising nanocarriers in the literature are iron oxide, gold, polymers, liposomes, micelles, fullerenes (carbon nanotubes, graphene), dendrimers, quantum dots, and nanodiamonds.
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  • 06 Aug 2021
Topic Review
Production of Chitosan Nanoparticles
Chitosan Nanoparticles are made from chitosan or its derivatives. The N-deacetylated derivative of chitin is an appealing biopolymer for producing nanoparticles because chitosan has a unique polymeric cationic nature, non-toxicity, high biocompatibility, mucoadhesive properties, absorption-enhancing qualities, and biodegradability.
  • 7.0K
  • 08 Oct 2022
Topic Review
IBM Mainframe Utility Programs
IBM mainframe utility programs are utility software supplied with IBM mainframe operating systems such as MVS and zOS to carry out various tasks associated with maintenance of the computer system or datasets. The following list describes utilities distributed with OS/360 and successors. No VSE or VM utilities are included.
  • 7.0K
  • 26 Oct 2022
Topic Review
Cydonia (Region of Mars)
Cydonia (/sɪˈdoʊniə/, /saɪˈdoʊniə/) is a region on the planet Mars that has attracted both scientific and popular interest. The name originally referred to the albedo feature (distinctively coloured area) that was visible from Earthbound telescopes. The area borders plains of Acidalia Planitia and the Arabia Terra highlands. The area includes the regions: "Cydonia Mensae", an area of flat-topped mesa-like features, "Cydonia Colles", a region of small hills or knobs, and "Cydonia Labyrinthus", a complex of intersecting valleys. As with other albedo features on Mars, the name Cydonia was drawn from classical antiquity, in this case from Kydonia, a historic polis (or "city-state") on the island of Crete. Cydonia contains the "Face on Mars", located about halfway between Arandas Crater and Bamberg Crater.
  • 7.0K
  • 25 Oct 2022
Topic Review
Full-Color Realization of Micro-LED Displays
Emerging technologies, such as smart wearable devices, augmented reality (AR)/virtual reality (VR) displays, and naked-eye 3D projection, have gradually entered our lives, accompanied by an urgent market demand for high-end display technologies. Ultra-high-resolution displays, flexible displays, and transparent displays are all important types of future display technology, and traditional display technology cannot meet the relevant requirements. Micro-light-emitting diodes (micro-LEDs), which have the advantages of a high contrast, a short response time, a wide color gamut, low power consumption, and a long life, are expected to replace traditional liquid-crystal displays (LCD) and organic light-emitting diodes (OLED) screens and become the leaders in the next generation of display technology. However, there are two major obstacles to moving micro-LEDs from the laboratory to the commercial market. One is improving the yield rate and reducing the cost of the mass transfer of micro-LEDs, and the other is realizing a full-color display using micro-LED chips. This study will outline the three main methods for applying current micro-LED full-color displays, red, green, and blue (RGB) three-color micro-LED transfer technology, color conversion technology, and single-chip multi-color growth technology, to summarize present-day micro-LED full-color display technologies and help guide the follow-up research.
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  • 22 Dec 2020
Topic Review
UAV-based IoT
The Internet of Things (IoT), which consists of a large number of small low-cost devices, has become a leading solution for smart cities, smart agriculture, smart buildings, smart grids, e-healthcare, etc. Integrating unmanned aerial vehicles (UAVs) with IoT can result in an airborne UAV-based IoT (UIoT) system and facilitate various value-added services from sky to ground. In addition to wireless sensors, various kinds of IoT devices are connected in UIoT, making the network more heterogeneous. In a UIoT system, for achieving high throughput in an energy-efficient manner, it is crucial to design an efficient medium access control (MAC) protocol because the MAC layer is responsible for coordinating access among the IoT devices in the shared wireless medium. Thus, various MAC protocols with different objectives have been reported for UIoT.
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  • 07 Dec 2020
Topic Review
Hazard
A hazard is an agent which has the potential to cause harm to a vulnerable target. The terms "hazard" and "risk" are often used interchangeably. However, in terms of risk assessment, they are two very distinct terms. A hazard is any agent that can cause harm or damage to humans, property, or the environment. Risk is defined as the probability that exposure to a hazard will lead to a negative consequence, or more simply, a hazard poses no risk if there is no exposure to that hazard. Hazards can be dormant or potential, with only a theoretical probability of harm. An event that is caused by interaction with a hazard is called an incident. The likely severity of the undesirable consequences of an incident associated with a hazard, combined with the probability of this occurring, constitute the associated risk. If there is no possibility of a hazard contributing towards an incident, there is no risk. Hazards can be classified as different types in several ways. One of these ways is by specifying the origin of the hazard. One key concept in identifying a hazard is the presence of stored energy that, when released, can cause damage. Stored energy can occur in many forms: chemical, mechanical, thermal, radioactive, electrical, etc. Another class of hazard does not involve release of stored energy, rather it involves the presence of hazardous situations. Examples include confined or limited egress spaces, oxygen-depleted atmospheres, awkward positions, repetitive motions, low-hanging or protruding objects, etc. Hazards may also be classified as natural, anthropogenic, or technological. They may also be classified as health or safety hazards, by the populations that may be affected, and the severity of the associated risk. In most cases a hazard may affect a range of targets, and have little or no effect on others. Identification of hazards assumes that the potential targets are defined, and is the first step in performing a risk assessment.
  • 7.0K
  • 26 Oct 2022
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