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Topic Review
Drag Polar
The drag polar or drag curve is the relationship between the lift on an aircraft and its drag, expressed in terms of the dependence of the drag coefficient on the lift coefficient. It may be described by an equation or displayed in a diagram called a polar plot.
  • 9.6K
  • 24 Oct 2022
Topic Review
Onion Dome
An onion dome (Russian: луковичная глава, lúkovichnaya glavá; compare Russian: лук, luk, "onion") is a dome whose shape resembles an onion and is usually associated with Russia n architectural style. Such domes are often larger in diameter than the tholobate upon which they sit, and their height usually exceeds their width. These bulbous structures taper smoothly to a point. It is a typical feature of churches belonging to Russian Orthodox church. Occasionally, there are similar buildings in European countries like in Germany in Bavaria, (German: Zwiebelturm (literally "onion tower") in Austria, the Czech Republic, northeastern Italy, in other Eastern European countries and in Oriental regions like Mughal India, the Middle East and Central Asia. However, the old buildings outside of Russia usually do not have the distinctive typical construction of the Russian onion design. Probably the origin lies in the native architectural style of early Rus' tribes. Other types of Eastern Orthodox cupolas include helmet domes (for example, those of the Assumption Cathedral in Vladimir), Ukrainian pear domes (Saint Sophia Cathedral in Kiev), and Baroque bud domes (St. Andrew's Church in Kiev) or an onion-helmet mixture like the Saint Sophia Cathedral in Novgorod.
  • 9.6K
  • 31 Oct 2022
Topic Review
Non-Governmental Organisations and Sustainable Community Development
Alternative healthcare, community development, social justice, and education are all areas where non-governmental organisations (NGOs) are increasingly being recognised or promoted, but these efforts are hampered by government inefficiency and resource constraints. However, the statement of non-profit organisations is more complicated than simply comparing them to the government, as they may also suffer from a lack of resources and ineffective management, just like the government. Meanwhile, NGOs are generally defined by four characteristics: they are voluntary, non-partisan, non-profit, and non-criminal. According to Salamon and Anheier, seven distinct characteristics were used to categorise and differentiate NGOs. The seven characteristics are as follows: (1) formal (officially registered and governed); (2) private (having a separate organisation from the government); (3) non-profit distributing (different from the objectives of establishing a business organisation); (4) self-governing (privately managed); (5) voluntary (worked voluntarily); (6) non-religious (not motivated by preaching); and (7) non-political (not involved in promoting candidates in elections). These characteristics are particularly useful for identifying and differentiating NGOs from other organisations.
  • 9.6K
  • 13 Apr 2022
Topic Review
Starter Cultures in Foods
Starter cultures can be defined as preparations with a large number of cells that include a single type or a mixture of two or more microorganisms that are added to foods in order to take advantage of the compounds or products derived from their metabolism or enzymatic activity.
  • 9.6K
  • 19 Apr 2021
Topic Review
400 kV Double-Circuit Transmission Lines
A high-voltage AC double-circuit 400 kV overhead power transmission line runs from the city of Elk (Poland) to the city of Alytus (Lithuania). This international 400 kV power transmission line is potentially one of the strongest magnetic field-generating sources in the area. This 400 kV voltage double-circuit overhead transmission line and its surroundings were analyzed using the mathematical analytical methods of superposition and reflections. This research paper includes the calculation of the numerical values of the magnetic field and its distribution. The research showed that the values of the magnetic field strength near the international 400 kV power transmission line exceed the threshold values permitted by relevant standards. This overhead power line is connected to the general (50 Hz) power system and generates a highly intense magnetic field. It is suggested that experimental trials should be undertaken in order to determine the maximum values of the magnetic field strength. For the purpose of mitigating these values, it is suggested that the height of the support bars should be increased or that any individual and commercial activities near the object under investigation should be restricted.
  • 9.5K
  • 20 Apr 2021
Topic Review
Fine-tuned Universe
The fine-tuned universe is the proposition that the conditions that allow life in the universe can occur only when certain universal dimensionless physical constants lie within a very narrow range of values, so that if any of several fundamental constants were only slightly different, the universe would be unlikely to be conducive to the establishment and development of matter, astronomical structures, elemental diversity, or life as it is understood. Various possible explanations of ostensible fine-tuning are discussed among philosophers, scientists, theologians, and proponents and detractors of creationism. The fine-tuned universe observation is closely related to, but is not exactly synonymous with, the anthropic principle, which is often used as an explanation of apparent fine-tuning.
  • 9.5K
  • 28 Sep 2022
Topic Review
Carboniferous Rainforest Collapse
The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. It altered the vast coal forests that covered the equatorial region of Euramerica (Europe and America). This event may have fragmented the forests into isolated 'islands', which in turn caused dwarfism and, shortly after, extinction of many plant and animal species. Following the event, coal-forming tropical forests continued in large areas of the Earth, but their extent and composition were changed. The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of the Pennsylvanian (Upper Carboniferous).
  • 9.5K
  • 08 Oct 2022
Topic Review
Tachypsychia
Tachypsychia is a neurological condition that alters the perception of time, usually induced by physical exertion, drug use, or a traumatic event. For someone affected by tachypsychia, time perceived by the individual either lengthens, making events appear to slow down, or contracts, objects appearing as moving in a speeding blur. It is believed that tachypsychia is induced by a combination of high levels of dopamine and norepinephrine, usually during periods of great physical stress or in violent confrontation. Interestingly, a controlled experiment from 2007 suggests the subjective experience of time slowing down is actually an artifact of memory, not an actual trait of real-time perception. However, newer research seems to contradict this, with results showing that during high stress events a focus on action preparation actually does increase information processing, slowing down time perception. A 2012 review of most current research (including the 2007 study) seems to support this as well. Due to the contradictory research results and difficulty of accurately replicating the natural conditions in which the phenomenon occurs, there is still no set consensus on how tachypsychia functions.
  • 9.5K
  • 07 Nov 2022
Topic Review
Davidic Line
The Davidic line or House of David (Hebrew: בית דוד‎, romanized: Beit David) refers to the lineage of the Israelite king David through texts in the Hebrew Bible, the New Testament, and through the succeeding centuries. According to the Bible, David, of the Tribe of Judah, was the third king of the United Monarchy of Israel and Judah. He was later succeeded by his son, Solomon. After Solomon's death, the ten northern tribes rejected the Davidic line, refusing to accept Solomon's son, Rehoboam, and instead chose as king Jeroboam and formed the northern Kingdom of Israel. The southern tribes of Judah and Benjamin remained loyal to the House of David, and this kingdom came to be known as the Kingdom of Judah. All subsequent kings of Judah, except Athaliah, are said to be direct descendants of David. The kingdom fell to the Neo-Babylonian Empire in 587/6 BCE. The Hasmoneans, who established their own monarchy in Judea in the 2nd century BCE, were not considered connected to the Davidic line nor to the Tribe of Judah. In Judaism and Christianity, the Davidic Line is the bloodline from which the Hebrew Messiah has a patrilineal descent. In Jewish eschatology, the Messiah is a future Jewish king from the Davidic line, who is expected to rule the Jewish people during the Messianic Age and world to come. The Christian gospels claim that Jesus descends from the Davidic line and is therefore the legitimate Hebrew Messiah. The New Testament books of Matthew and Luke give two different accounts of the genealogy of Jesus that trace back to David.
  • 9.5K
  • 02 Dec 2022
Topic Review
Vision in Fishes
Vision is an important sensory system for most species of fish. Fish eyes are similar to the eyes of terrestrial vertebrates like birds and mammals, but have a more spherical lens. Birds and mammals (including humans) normally adjust focus by changing the shape of their lens, but fish normally adjust focus by moving the lens closer to or further from the retina. Fish retinas generally have both rod cells and cone cells (for scotopic and photopic vision), and most species have colour vision. Some fish can see ultraviolet and some are sensitive to polarized light. Among jawless fishes, the lamprey has well-developed eyes, while the hagfish has only primitive eyespots. The ancestors of modern hagfish, thought to be the protovertebrate were evidently pushed to very deep, dark waters, where they were less vulnerable to sighted predators, and where it is advantageous to have a convex eye-spot, which gathers more light than a flat or concave one. Fish vision shows evolutionary adaptation to their visual environment, for example deep sea fish have eyes suited to the dark environment.
  • 9.5K
  • 10 Nov 2022
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