Random Articles (Page 4)
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π Dynamic Soaring
Dynamic soaring is a flying technique used to gain energy by repeatedly crossing the boundary between air masses of different velocity. Such zones of wind gradient are generally found close to obstacles and close to the surface, so the technique is mainly of use to birds and operators of radio-controlled gliders, but glider pilots are sometimes able to soar dynamically in meteorological wind shears at higher altitudes.
Dynamic soaring is sometimes confused with slope soaring which is a technique for achieving elevation.
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- "Dynamic Soaring" | 2023-12-17 | 92 Upvotes 38 Comments
π Effects of Stress on Memory
The effects of stress on memory include interference with a person's capacity to encode memory and the ability to retrieve information. Stimuli, like stress, improved memory when it was related to learning the subject. During times of stress, the body reacts by secreting stress hormones into the bloodstream. Stress can cause acute and chronic changes in certain brain areas which can cause long-term damage. Over-secretion of stress hormones most frequently impairs long-term delayed recall memory, but can enhance short-term, immediate recall memory. This enhancement is particularly relative in emotional memory. In particular, the hippocampus, prefrontal cortex and the amygdala are affected. One class of stress hormone responsible for negatively affecting long-term, delayed recall memory is the glucocorticoids (GCs), the most notable of which is cortisol. Glucocorticoids facilitate and impair the actions of stress in the brain memory process. Cortisol is a known biomarker for stress. Under normal circumstances, the hippocampus regulates the production of cortisol through negative feedback because it has many receptors that are sensitive to these stress hormones. However, an excess of cortisol can impair the ability of the hippocampus to both encode and recall memories. These stress hormones are also hindering the hippocampus from receiving enough energy by diverting glucose levels to surrounding muscles.
Stress affects many memory functions and cognitive functioning of the brain. There are different levels of stress and the high levels can be intrinsic or extrinsic. Intrinsic stress level is triggered by a cognitive challenge whereas extrinsic can be triggered by a condition not related to a cognitive task. Intrinsic stress can be acutely and chronically experienced by a person. The varying effects of stress on performance or stress hormones are often compared to or known as "inverted-u" which induce areas in learning, memory and plasticity. Chronic stress can affect the brain structure and cognition.
Studies considered the effects of both intrinsic and extrinsic stress on memory functions, using for both of them Pavlovian conditioning and spatial learning. In regard to intrinsic memory functions, the study evaluated how stress affected memory functions that was triggered by a learning challenge. In regard to extrinsic stress, the study focused on stress that was not related to cognitive task but was elicited by other situations. The results determined that intrinsic stress was facilitated by memory consolidation process and extrinsic stress was determined to be heterogeneous in regard to memory consolidation. Researchers found that high stress conditions were a good representative of the effect that extrinsic stress can cause on memory functioning. It was also proven that extrinsic stress does affect spatial learning whereas acute extrinsic stress does not.
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- "Effects of Stress on Memory" | 2024-12-10 | 19 Upvotes 5 Comments
π Flow Chemistry
In flow chemistry, a chemical reaction is run in a continuously flowing stream rather than in batch production. In other words, pumps move fluid into a tube, and where tubes join one another, the fluids contact one another. If these fluids are reactive, a reaction takes place. Flow chemistry is a well-established technique for use at a large scale when manufacturing large quantities of a given material. However, the term has only been coined recently for its application on a laboratory scale. Often, microreactors are used.
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- "Flow Chemistry" | 2020-03-19 | 25 Upvotes 16 Comments
π Trap Street
In cartography, a trap street is a fictitious entry in the form of a misrepresented street on a map, often outside the area the map nominally covers, for the purpose of "trapping" potential copyright violators of the map who, if caught, would be unable to explain the inclusion of the "trap street" on their map as innocent. On maps that are not of streets, other "copyright trap" features (such as nonexistent towns, or mountains with the wrong elevations) may be inserted or altered for the same purpose.
Trap streets are often nonexistent streets; but sometimes, rather than actually depicting a street where none exists, a map will misrepresent the nature of a street in a fashion that can still be used to detect copyright violators but is less likely to interfere with navigation. For instance, a map might add nonexistent bends to a street, or depict a major street as a narrow lane, without changing its location or its connections to other streets.
Trap streets are rarely acknowledged by publishers. One known case is a popular driver's atlas for the city of Athens, Greece, which has a warning inside its front cover that potential copyright violators should beware of trap streets.
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- "Trap Street" | 2023-05-01 | 61 Upvotes 29 Comments
- "Trap Street" | 2018-08-11 | 74 Upvotes 21 Comments
- "Trap street" | 2013-01-01 | 34 Upvotes 22 Comments
π Campanology
Campanology () is the scientific and musical study of bells. It encompasses the technology of bells β how they are founded, tuned and rung β as well as the history, methods, and traditions of bellringing as an art.
It is common to collect together a set of tuned bells and treat the whole as one musical instrument. Such collectionsΒ β such as a Flemish carillon, a Russian zvon, or an English "ring of bells" used for change ringingΒ β have their own practices and challenges; and campanology is likewise the study of perfecting such instruments and composing and performing music for them.
In this sense, however, the word campanology is most often used in reference to relatively large bells, often hung in a tower. It is not usually applied to assemblages of smaller bells, such as a glockenspiel, a collection of tubular bells, or an Indonesian gamelan.
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- "Campanology" | 2023-04-04 | 52 Upvotes 35 Comments
π Descent of Inanna into the Underworld
The Descent of Inanna into the Underworld (or, in its Akkadian version, Descent of Ishtar into the Underworld) or Angalta ("From the Great Sky") is a Sumerian myth that narrates the descent of the goddess Inanna (Ishtar in Akkadian) into the Underworld to overthrow its ruler, her sister Ereshkigal, the "Queen of the Dead." But following the removal of her adornments, she perishes and her corpse is suspended on a nail. The god Enki intervenes indirectly, restoring Inanna to life. However, on her return journey, Inanna is required to deliver another living human in exchange for her freedom. She selects Dumuzi, her spouse, who is abruptly transported to the Underworld. In response to the pleas of Dumuzi's sister, Geshtinanna, his circumstances are somewhat ameliorated: he is permitted to remain in the Underworld for only a portion of the year, with his sister assuming his role for the remaining duration.
The myth exists in two main versions: one in Sumerian and the other in Akkadian. The Akkadian version was first discovered and translated in the 1860s. The existence of the longer and older Sumerian version was first established in the early 20th century, but it required approximately fifty years for epigraphists to fully reconstruct and translate it.
The story of Descent of Inanna into the Underworld offers insights into Mesopotamian culture through its numerous characters and developed plot. The influence of this culture on subsequent civilizations is evident in the traces of Mesopotamian elements found in Greece, Phoenicia, and the Old Testament. In the 20th century, the story was used by some psychoanalysis theorists to illustrate psychic mechanisms.
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- "Descent of Inanna into the Underworld" | 2025-07-30 | 36 Upvotes 10 Comments
π The Larkin Soap Company
The Larkin Company, also known as the Larkin Soap Company, was a company founded in 1875 in Buffalo, New York as a small soap factory. It grew tremendously throughout the late 1800s and into the first quarter of the 1900s with an approach called "The Larkin Idea" that transformed the company into a mail-order conglomerate that employed 2,000 people and had annual sales of $28.6Β million (equivalent to $434,986,000 in 2023) in 1920. The company's success allowed them to hire Frank Lloyd Wright to design the iconic Larkin Administration Building which stood as a symbol of Larkin prosperity until the company's demise in the 1940s.
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- "The Larkin Soap Company" | 2024-10-13 | 31 Upvotes 27 Comments
π Perturbation Theory
In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middle step that breaks the problem into "solvable" and "perturbative" parts. In perturbation theory, the solution is expressed as a power series in a small parameter . The first term is the known solution to the solvable problem. Successive terms in the series at higher powers of usually become smaller. An approximate 'perturbation solution' is obtained by truncating the series, usually by keeping only the first two terms, the solution to the known problem and the 'first order' perturbation correction.
Perturbation theory is used in a wide range of fields, and reaches its most sophisticated and advanced forms in quantum field theory. Perturbation theory (quantum mechanics) describes the use of this method in quantum mechanics. The field in general remains actively and heavily researched across multiple disciplines.
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- "Perturbation Theory" | 2023-03-19 | 91 Upvotes 31 Comments
π Finger Binary
Finger binary is a system for counting and displaying binary numbers on the fingers of one or more hands. It is possible to count from 0 to 31 (25 β 1) using the fingers of a single hand, from 0 through 1023 (210 β 1) if both hands are used, or from 0 to 1,048,575 (220 β 1) if the toes on both feet are used as well.
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- "Finger Binary" | 2015-08-30 | 72 Upvotes 45 Comments
- "Finger binary" | 2013-12-07 | 50 Upvotes 48 Comments
π Agglutinative Language
An agglutinative language is a type of synthetic language with morphology that primarily uses agglutination. Words may contain different morphemes to determine their meanings, but all of these morphemes (including stems and affixes) remain, in every aspect, unchanged after their unions. This results in generally more easily deducible word meanings if compared to fusional languages, which allow modifications in either or both the phonetics or spelling of one or more morphemes within a word. This usually results in a shortening of the word, or it provides easier pronunciation.
Agglutinative languages have generally one grammatical category per affix while fusional languages have multiple. The term was introduced by Wilhelm von Humboldt to classify languages from a morphological point of view. It is derived from the Latin verb agglutinare, which means "to glue together".
Non-agglutinative synthetic languages are fusional languages; morphologically, they combine affixes by "squeezing" them together, drastically changing them in the process, and joining several meanings in a single affix (for example, in the Spanish word comΓ "I ate", the suffix -Γ carries the meanings of first person, singular number, past tense, perfective aspect, indicative mood, active voice.) The term agglutinative is sometimes incorrectly used as a synonym for synthetic. Used in this way, the term embraces both fusional languages and inflected languages. The agglutinative and fusional languages are two ends of a continuum, with various languages falling more toward one or the other end. For example, Japanese is generally agglutinative, but displays fusion in otΕto (εΌ, younger brother), from oto+hito (originally woto+pito), and in its non-affixing verb conjugations. A synthetic language may use morphological agglutination combined with partial usage of fusional features, for example in its case system (e.g., German, Dutch, and Persian).
Agglutinative languages tend to have a high rate of affixes or morphemes per word, and to be very regular, in particular with very few irregular verbs. For example, Japanese has very few irregular verbs β only two are significantly irregular, and there are only about a dozen others with only minor irregularity; Ganda has only one (or two, depending on how "irregular" is defined); while in the Quechua languages, all the ordinary verbs are regular. Korean has only ten irregular forms of conjugation except for the passive and causative conjugations. Georgian is an exception; it is highly agglutinative (with up to eight morphemes per word), but it has a significant number of irregular verbs with varying degrees of irregularity.
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- "Agglutinative Language" | 2019-11-19 | 59 Upvotes 29 Comments