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Topic Review

Corynebacterium

Corynebacterium species are frequent constituents of the normal bacterial flora of the conjunctival sac and are common as well on human skin and mucous membranes and in the intestines.

6.2K
18 Mar 2021

Topic Review

History of the Aircraft Carrier

Aircraft carriers are warships that evolved from balloon-carrying wooden vessels into nuclear-powered vessels carrying scores of fixed- and rotary-wing aircraft. Since their introduction they have allowed naval forces to project air power great distances without having to depend on local bases for staging aircraft operations. Balloon carriers were the first ships to deploy manned aircraft, used during the 19th and early 20th century, mainly for observation purposes. The advent of fixed-wing aircraft in 1903 was followed in 1910 by the first flight from the deck of a US Navy cruiser. Seaplanes and seaplane tender support ships, such as HMS Engadine, followed. The development of flat top vessels produced the first large fleet ships. This evolution was well underway by the early to mid-1920s, resulting in the commissioning of ships such as Hōshō (1922), HMS Hermes (1924), Béarn (1927), and the Lexington-class aircraft carriers (1927). Most early aircraft carriers were conversions of ships that were laid down (or had even served) as different ship types: cargo ships, cruisers, battlecruisers, or battleships. During the 1920s, several navies started ordering and building aircraft carriers that were specifically designed as such. This allowed the design to be specialized to their future role, and resulted in superior ships. During the Second World War, these ships would become the backbone of the carrier forces of the US, British, and Japanese navies, known as fleet carriers. World War II saw the first large-scale use of aircraft carriers and induced further refinement of their launch and recovery cycle leading to several design variants. The USA built small escort carriers, such as USS Bogue, as a stop-gap measure to provide air support for convoys and amphibious invasions. Subsequent light aircraft carriers, such as USS Independence, represented a larger, more "militarized" version of the escort carrier concept. Although the light carriers usually carried the same size air groups as escort carriers, they had the advantage of higher speed as they had been converted from cruisers under construction.

6.2K
07 Nov 2022

Topic Review

CO₂Separation Techniques

Energy plants, industries, as well as other sources of carbon dioxide (CO2) result in global warming and affect the planet. CO2 is separated from flue gas during combustion using a variety of advanced separation techniques. There are several techniques involved, such as absorption, adsorption, chemical looping, membrane separation, and cryogenics.

6.2K
13 Dec 2022

Topic Review

Brahmā (Buddhism)

Brahmā is a leading god (deva) and heavenly king in Buddhism. He was adopted from other Indian religions such as Hinduism that considered him a protector of teachings (dharmapala), and he is never depicted in early Buddhist texts as a creator god. In Buddhist tradition, it was the deity Brahma Sahampati who appeared before the Buddha and urged him to teach, once the Buddha attained enlightenment but was unsure if he should teach his insights to anyone. Brahma is a part of the Buddhist cosmology, and lords over the heavenly realm of rebirth called the Brahmaloka – the most sought after realm for afterlife and reincarnation in Buddhist traditions. Brahma is generally represented in Buddhist culture as a god with four faces and four arms, and variants of him are found in both Theravada and Mahayana Buddhist cultures. The origins of Brahma in Buddhism and other Indian religions are uncertain, in part because several related words such as one for metaphysical Ultimate Reality (Brahman), and priest (Brahmin) are found in the Vedic literature. According to KN Jayatilleke, the Rigveda expresses skepticism about major deities such as Indra whether he even exists, as well as whether the universe has any creator and can this ever be known, as evidenced in its eighth and tenth book, particularly in its Nasadiya Sukta. The late Vedic hymns had begun inquiring the nature of true and valid knowledge, empirical verification and absolute reality. The early Upanishads built upon this theme, while in parallel there emerged Buddhism, Jainism and other skeptical traditions. Buddhism used the term Brahma to deny a creator as well as to delegate him (and other deities such as Indra) as less important than the Buddha. In Hindu literature, one of the earliest mention of deity Brahma with Vishnu and Shiva is in the fifth Prapathaka (lesson) of the Maitrayaniya Upanishad, probably composed in late 1st millennium BCE, after the rise of Buddhism. The spiritual concept of Brahman is far older, and some scholars suggest deity Brahma may have emerged as a personal conception and icon with attributes (saguna version) of the impersonal universal principle called Brahman. The Buddhists attacked the concept of Brahma, states Gananath Obeyesekere, and thereby polemically attacked the Vedic and Upanishadic concept of gender neutral, abstract metaphysical Brahman. This critique of Brahma in early Buddhist texts aim at ridiculing the Vedas, but the same texts simultaneously call metta (loving-kindness, compassion) as the state of union with Brahma. The early Buddhist approach to Brahma was to reject any creator aspect, while retaining the Brahmavihara aspects of Brahma, in the Buddhist value system. Deity Brahma is also found in the samsara doctrine and cosmology of early Buddhism. Brahma is known as Fantian (梵天) in Chinese, Bonten (梵天) in Japanese, Pomch'on in Korean, Phra Phrom in Thai, and Tshangs pa in Tibetan.

6.2K
05 Dec 2022

Topic Review

Inedia (Latin for "fasting") or breatharianism /brɛθˈɛəriənɪzəm/ is the belief that it is possible for a person to live without consuming food. Breatharians claim that food, and in some cases water, are not necessary for survival, and that humans can be sustained solely by prana, the vital life force in Hinduism. According to Ayurveda, sunlight is one of the main sources of prana, and some practitioners believe that it is possible for a person to survive on sunlight alone. The terms breatharianism or inedia may also refer to this philosophy when it is practiced as a lifestyle in place of the usual diet. Breatharianism is considered a deadly pseudoscience by scientists and medical professionals, and several adherents of these practices have died from starvation and dehydration. Though it is common knowledge that biological entities require sustenance to survive, breatharianism continues.

6.2K
25 Oct 2022

Topic Review

A utopia (/juːˈtoʊpiə/ yoo-TOH-pee-ə) is an imaginary community or society that possesses highly desirable or nearly perfect qualities for its citizens. The term was coined by Sir Thomas More for his 1516 book Utopia, describing a fictional island society in the south Atlantic Ocean off the coast of South America. The opposite of a utopia is a dystopia, which dominates the fictional literature from the 1950s onwards, chiefly because of the impact of George Orwell's Nineteen Eighty-Four, published in 1949. However, the term can also denote actual experiments in what participants regard as a vastly superior manner of living, generally in what are termed intentional communities. In common parlance it is synonymous with "impossible", "far-fetched", and "deluded". Literary utopias focus on, amongst other things, equality, in such categories as economics, government and justice, with the method and structure of proposed implementation varying based on ideology. Lyman Tower Sargent argues that the nature of a utopia is inherently contradictory because societies are not homogeneous and have desires which conflict and therefore cannot simultaneously be satisfied. According to Sargent:

6.2K
08 Nov 2022

Topic Review

Fruit Vinegar Production

The production of fruit vinegars as a way of making use of fruit by-products is an option widely used by the food industry, since surplus or second quality fruit can be used without compromising the quality of the final product. The acetic nature of vinegars and its subsequent impact on the organoleptic properties of the final product allows almost any type of fruit to be used for its elaboration.

6.2K
13 May 2021

Topic Review

COTS-Based Architectural Framework

This research tackles issues such as the reliability and efficiency of real-time control systems based on commercial off-the-shelf (COTS) components. A strong emphasis is placed on finding novel efficient solutions based on standardized and commercially available off-the-shelf hardware/software components. In this direction, this research applies credible and feasible methodologies (e.g., model-based design, component-based design, formal verification, real-time scheduling, prototyping, and validation) in an innovative enhanced way. As an important outcome, a versatile integrative design approach and architectural framework (VIDAF) is proposed, which supports the development and implementation of reliable real-time control systems and applications using commercial off-the-shelf components. The feasibility and applicability of the proposed system’s architecture are evaluated and validated through a system application in embedded real-time control in manufacturing. The research outcomes are expected to have a positive impact on emerging areas such as the Industrial Internet of Things (IIoT).

6.2K
28 Oct 2020

Topic Review

Electrospinning

Relative to many other nanofiber formation techniques, the electrospinning technique exhibits superior nanofiber formation when considering cost and manufacturing complexity for many situations. Aligned electrospun nanofibers have applications in nanocomposite structures and energy storage devices in addition to applications like air filtration, desalination, tissue engineering, textiles etc. The specific strength and dielectric constant are important to understand mechanical and dielectric properties of electrospun fibers and tailor these properties in the field of composite and energy applications.

6.2K
20 Jan 2021

Topic Review

Structure of Oxide Perovskite

Materials crystalizing in the perovskite crystal structure are common crystals that are currently employed for multiples applications, including transistors, solar cells, light-emitting devices, memories, catalysts, and superconductors.One of the biggest players within the perovskite structures is the family of oxide perovskites. This is a prominent family with the general formula of ABO3, where A commonly designates an alkaline or rare earth metal cation, occupying the 12-fold coordinated cuboctahedral cages of the oxygen sub-lattice, and B stands for a transition-metal cation (e.g., Fe, Ni, Mn, Co, Cu, or Ti) coordinated with six oxygen atoms in an octahedral coordination. In fact, in the perovskite structure, distortions frequently occur due to the deviation from ideal values of ionic size ratios between the different A, B, and O sites of the crystal. In addition, A or B cations may have distinctive sizes and valences that could result into oxygen non-stoichiometry, involving both oxygen excess and/or oxygen deficiency.

6.2K
24 Sep 2021

Topic Review

The White Sea is a small shallow semi-closed sea in the North-West of Russia. It is strongly affected by induced tides, so the tidal motion dominates in the sea. Sea ice is seasonal and the water salinity is less than in the neighbouring Barents sea due to strong river discharge. In this entry, we focus on the sources of data on the Sea.

6.2K
21 Jan 2021

Topic Review

Vascular Endothelial Growth Factors

Vascular endothelial growth factors (VEGFs) are primary regulators of blood and lymphatic vessels. Hemangiogenic VEGFs (VEGF-A, PlGF, and VEGF-B) target mostly blood vessels, while the lymphangiogenic VEGFs (VEGF-C and VEGF-D) target mostly lymphatic vessels. Blocking VEGF-A is used today to treat several types of cancer (“antiangiogenic therapy”). However, in other diseases, it would be beneficial to do the opposite, namely to increase the activity of VEGFs. For example, VEGF-A could generate new blood vessels to protect from heart disease, and VEGF-C could generate new lymphatics to counteract lymphedema. Clinical trials that tried to stimulate blood vessel growth in ischemic diseases have been disappointing so far, and the first clinical trials targeting the lymphatic vasculature have progressed to phase II. Antiangiogenic drugs targeting VEGF-A such as bevacizumab or aflibercept neutralize the growth factor directly. However, since VEGF-C and VEGF-D are produced as inactive precursors, novel drugs against the lymphangiogenic VEGFs could also target the enzymatic activation of VEGF-C and VEGF-D. Because of the delicate balance between too much and too little vascular growth, a detailed understanding of the activation of the VEGF-C and VEGF-D is needed before such concepts can be converted into safe and efficacious therapies.

6.2K
30 Mar 2021

Topic Review

Materials Science, Glasses

Glasses are solid amorphous materials which transform into liquids upon heating through the glass transition. The International Commission on Glass defines glass as a state of matter, usually produced when a viscous molten material is cooled rapidly to below its glass transition temperature, with insufficient time for a regular crystal lattice to form. The solid-like behaviour of glasses is separated from the liquid-like behaviour at higher temperatures by the glass transition temperature, Tg. The IUPAC Compendium on Chemical Terminology defines glass transition as a second order transition in which a supercooled melt yields, on cooling, a glassy structure. It states that below the glass-transition temperature the physical properties of glasses vary in a manner similar to those of the crystalline phase. Moreover, it is deemed that the bonding structure of glasses has the same symmetry signature in terms of Hausdorff-Besikovitch dimensionality of chemical bonds as for the crystalline materials.

6.2K
09 May 2024

Topic Review

Persuasive Technology

Persuasive technology is broadly defined as technology that is designed to change attitudes or behaviors of the users through persuasion and social influence, but not necessarily through coercion. Such technologies are regularly used in sales, diplomacy, politics, religion, military training, public health, and management, and may potentially be used in any area of human-human or human-computer interaction. Most self-identified persuasive technology research focuses on interactive, computational technologies, including desktop computers, Internet services, video games, and mobile devices, but this incorporates and builds on the results, theories, and methods of experimental psychology, rhetoric, and human-computer interaction. The design of persuasive technologies can be seen as a particular case of design with intent.

6.2K
28 Sep 2022

Topic Review

Detection of Adulteration of Honey

Nowadays, adulteration of honey is a major concern among authorities in order to ensure its quality by imposing specific standards that allow the honey to be competitive in the market. Traditionally, the identification of adulteration of honey is performed by physicochemical methods. However, spectroscopic techniques are considerably more practical when detecting impurities in honey due to fraudulent acts, as these techniques are easy to execute, more rapid, and more reliable than physicochemical methods.

6.2K
17 Jan 2022

Topic Review

BeiDou Navigation Satellite System

The BeiDou Navigation Satellite System (BDS) is a Chinese satellite navigation system. It consists of two separate satellite constellations. The first BeiDou system, officially called the BeiDou Satellite Navigation Experimental System and also known as BeiDou-1, consists of three satellites which since 2000 has offered limited coverage and navigation services, mainly for users in China and neighboring regions. Beidou-1 was decommissioned at the end of 2012. The second generation of the system, officially called the BeiDou Navigation Satellite System (BDS) and also known as COMPASS or BeiDou-2, became operational in China in December 2011 with a partial constellation of 10 satellites in orbit. Since December 2012, it has been offering services to customers in the Asia-Pacific region. In 2015, China started the build-up of the third generation BeiDou system (BeiDou-3) in the global coverage constellation. The first BDS-3 satellite was launched on 30 March 2015. As of January 2018, nine BeiDou-3 satellites have been launched. BeiDou-3 will eventually consist of 35 satellites and is expected to provide global services upon completion in 2020. When fully completed, BeiDou will provide an alternative global navigation satellite system to the United States owned Global Positioning System (GPS), and is expected to be more accurate than the GPS. It was claimed in 2016 that BeiDou-3 will reach millimeter-level accuracy (with post-processing), which is ten times more accurate than the finest level of GPS. According to China Daily, in 2015, fifteen years after the satellite system was launched, it was generating a turnover of $31.5 billion per annum for major companies such as China Aerospace Science and Industry Corp, AutoNavi Holdings Ltd, and China North Industries Group Corp.

6.2K
29 Nov 2022

Topic Review

Artificial Neural Networks

Artificial Intelligence (AI) researches and builds intelligent software and machines, provides a particular solution to a particular defined complex problem. To carry out these tasks, it uses models and algorithms such as genetic algorithms, particle swarm optimization, artificial neural networks (ANNs), and hybrid models (two or more of the above). ANNs are flexible to accommodate non-linear and non-physical data; however, they require large multidimensional data set to reduce the risk of extrapolation. ANNs are widely used in different branches of science for their learning ability and adaptability to various settings.

6.2K
12 Apr 2021

Topic Review

Traditional Mexican Diet

Grains, legumes, and vegetables were the most representative food groups in the traditional Mexican diet (TMexD), as these were mentioned in most (75%) of the studies, including all the subgroups evaluated. Additionally, maize (mostly as tortillas), beans, squash, tomato, chile, and onion are potentially fundamental elements of the TMexD, as these were the only individual foods cited in most studies, including all the subgroups evaluated. Indeed, maize (a grain), beans (a legume), and squash (a vegetable) have long represented the basic foods in Mexico, as they form part of the ancient agro-ecosystem known as Milpa. Other groups that were also mentioned in all the studies and subgroup analyses were maize products, fruits, beverages, fish and seafood, meats, sweets and sweeteners, and herbs and condiments. However, these were mentioned in different frequencies in the different subgroups assessed (i.e., in ≥75% of studies in some subgroups while in only 50% of studies in others).

6.2K
05 Aug 2021

Topic Review

Scunthorpe Problem

The Scunthorpe problem is the unintentional blocking of websites, e-mails, forum posts or search results by a spam filter or search engine because their text contains a string (or substring) of letters that appear to have an obscene or otherwise unacceptable meaning. Names, abbreviations, and technical terms are most often cited as being affected by the issue. The problem arises since computers can easily identify strings of text within a document, but interpreting words of this kind requires considerable ability to interpret a wide range of contexts, possibly across many cultures, which is an extremely difficult task. As a result, broad blocking rules may result in false positives affecting innocent phrases.

6.2K
14 Oct 2022

Topic Review

Around the World Sailing Record

The first around the world sailing record for circumnavigation of the world was Juan Sebastián Elcano and the remaining members of Ferdinand Magellan's crew who completed their journey in 1522. The first solo record was set by Joshua Slocum in the Spray (1898). The current record holders are IDEC 3, skippered by Francis Joyon in 40 days, 23 hours, 30 minutes and 30 seconds for a crewed journey, and François Gabart with Macif in 42 days, 16 hours, 40 minutes and 35 seconds for a solo journey. Most races or solo attempts start from Europe. Due to the configuration of the continents, sailing around the world consists of sailing on the Southern Ocean around the Antarctica continent, passing south of Cape Horn, Cape of Good Hope and Cape Leeuwin. Since 1918 the Panama Canal is an option but the locks must be entered and exited using engine power. Large stretches of the canal can be crossed under sail power. Sailing around the world can be done by two directions: eastward or westward. The dominant winds and currents (outside tropical areas) make the voyage eastwards on the Southern hemisphere faster, most skippers and yachts who race prefer this route. Today, the multihulls perform much better than monohulls and hold the best times. Leisure yacht skippers who prefer tropical seas more often go westward, using the trade winds (and the Panama canal). The Jules Verne Trophy is awarded to the skipper who breaks the previous Jules Verne record, starting from an imaginary line between the Créac'h lighthouse on Ouessant (Ushant) Island, France , and the Lizard Lighthouse, United Kingdom . This has not always been the OUTRIGHT record. The records are homologated by the World Sailing Speed Record Council (WSSRC). According to the WSSRC, for around the world sailing records, there is a rule saying that the length must be at least 21,600 nmi calculated along the shortest possible track from the starting port and back that does not cross land and does not go below 63°S. The great-circle distance formulas are to be used, assuming that the great circle length is 21,600 nmi. It is allowed to have one single waypoint to lengthen the calculated track. The equator must be crossed. In reality, this means that the boat should pass a waypoint at or not far from the antipode of the starting port of the journey (the exact position depends on how short the shortest possible track is). For example, the Vendée Globe starts at 46°N 2°W, has a waypoint at 57°S 180°E, and barely makes the distance requirement. The participants don't have to go to the antipode at 46°S 178°E since the rounding of Africa gives extra distance.

6.2K
11 Nov 2022

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