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🔗 Spaceflight 🔗 Physics 🔗 Rocketry

The Tsiolkovsky rocket equation, classical rocket equation, or ideal rocket equation is a mathematical equation that describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself using thrust by expelling part of its mass with high velocity can thereby move due to the conservation of momentum.

${\displaystyle \Delta v=v_{\text{e}}\ln {\frac {m_{0}}{m_{f}}}=I_{\text{sp}}g_{0}\ln {\frac {m_{0}}{m_{f}}}}$

where:

${\displaystyle \Delta v\ }$ is delta-v – the maximum change of velocity of the vehicle (with no external forces acting).

${\displaystyle m_{0}}$ is the initial total mass, including propellant, also known as wet mass.

${\displaystyle m_{f}}$ is the final total mass without propellant, also known as dry mass.

${\displaystyle v_{\text{e}}=I_{\text{sp}}g_{0}}$ is the effective exhaust velocity, where:

${\displaystyle I_{\text{sp}}}$ is the specific impulse in dimension of time.

${\displaystyle g_{0}}$ is standard gravity.

${\displaystyle \ln }$ is the natural logarithm function.

🔗 Socialism 🔗 Urban studies and planning 🔗 New Jersey

The North American Phalanx was a secular utopian socialist commune located in Colts Neck Township, Monmouth County, New Jersey. The community was the longest-lived of about 30 Fourierist Associations in the United States which emerged during a brief burst of popularity during the decade of the 1840s.

The North American Phalanx was established in September 1843 and included the active participation of writer Albert Brisbane and newspaper publisher Horace Greeley, two of the leading figures of the Fourierist movement. The Association was disbanded in January 1856, following a catastrophic fire which destroyed a number of the community's productive enterprises. At the time of its termination it was the last of about 30 Fourierist Associations established during the 1840s still in existence and thus was the longest-lived.

The main residential dwelling of the phalanx, a three-story wooden structure, stood vacant until it was itself destroyed by fire in November 1972.

🔗 China 🔗 Maps

Mao Kun map, usually referred to in modern Chinese sources as Zheng He's Navigation Map (simplified Chinese: 郑和航海图; traditional Chinese: 鄭和航海圖; pinyin: Zhèng Hé hánghǎi tú), is a set of navigation charts published in the Ming dynasty military treatise Wubei Zhi. The book was compiled by Mao Yuanyi in 1621 and published in 1628; the name of the map refers to his grandfather Mao Kun (Chinese: 茅坤; pinyin: Máo Kūn) from whose library the map is likely to have originated. The map is often regarded as a surviving document from the expeditions of Zheng He in addition to accounts written by Zheng's officers, such as Yingya Shenglan by Ma Huan, Xingcha Shenglan by Fei Xin, and Xiyang Fanguo Zhi by Gong Zhen. It is the earliest Chinese map to give an adequate representation of Southern Asia, Persia, Arabia and East Africa.

🔗 Amateur radio

The British Amateur Television Club (BATC) is the world's largest television technology club; it has members in the UK and all around the world and is a non-profit making club run by an elected committee of volunteers for the benefit of its members. Membership is open to all who are interested in television, amateur or professional, indeed the club has many members who work for major broadcasting companies.

🔗 United States 🔗 Medicine 🔗 Sociology 🔗 United States/Hispanic and Latino Americans

The Hispanic paradox is an epidemiological finding that Hispanic Americans tend to have health outcomes that "paradoxically" are comparable to, or in some cases better than, those of their U.S. non-Hispanic White counterparts, even though Hispanics have lower average income and education. Low socioeconomic status is almost universally associated with worse population health and higher death rates everywhere in the world. The paradox usually refers in particular to low mortality among Hispanics in the United States relative to non-Hispanic Whites. According to the Center for Disease Control's 2015 Vital Signs report, Hispanics in the United States had a 24% lower risk of mortality, as well as lower risk for nine of the fifteen leading causes of death as compared to Whites.

There are multiple hypotheses which aim to determine the reason for the existence of this paradox. Some attribute the Hispanic paradox to biases created by patterns or selection in migration. One such hypothesis is the Salmon Bias, which suggests that Hispanics tend to return home towards the end of their lives, ultimately rendering an individual "statistically immortal" and thus artificially lowering mortality for Hispanics in the United States. Another hypothesis in this group is that of the Healthy Migrant, which attributes the better health of Hispanics to the assumption that the healthiest and strongest members of a population are most likely to migrate.

Other hypotheses around the Hispanic paradox maintain that the phenomenon is real, and is caused by sociocultural factors which characterize the Hispanic population. Many of these factors can be described under the more broad categories of cultural values, interpersonal context, and community context. Some health researchers attribute the Hispanic paradox to different eating habits, especially the relatively high intake of legumes such as beans and lentils.

🔗 Evolutionary biology 🔗 Ecology 🔗 Project-independent assessment

Motion camouflage is camouflage which provides a degree of concealment for a moving object, given that motion makes objects easy to detect however well their coloration matches their background or breaks up their outlines.

The principal form of motion camouflage, and the type generally meant by the term, involves an attacker's mimicking the optic flow of the background as seen by its target. This enables the attacker to approach the target while appearing to remain stationary from the target's perspective, unlike in classical pursuit (where the attacker moves straight towards the target at all times, and often appears to the target to move sideways). The attacker chooses its flight path so as to remain on the line between the target and some landmark point. The target therefore does not see the attacker move from the landmark point. The only visible evidence that the attacker is moving is its looming, the change in size as the attacker approaches.

Camouflage is sometimes facilitated by motion, as in the leafy sea dragon and some stick insects. These animals complement their passive camouflage by swaying like plants in the wind or ocean currents, delaying their recognition by predators.

First discovered in hoverflies in 1995, motion camouflage by minimizing optic flow has been demonstrated in another insect order, dragonflies, as well as in two groups of vertebrates, falcons and echolocating bats. Since bats hunt at night, they cannot use camouflage. Instead they use an efficient homing strategy called constant absolute target direction. It has been suggested that anti-aircraft missiles could benefit from similar techniques.

🔗 Biology 🔗 Politics 🔗 Psychology 🔗 Neuroscience 🔗 Genetics 🔗 Physiology 🔗 Physiology/neuro 🔗 Evolutionary biology 🔗 Conservatism

A number of studies have found that biology can be linked with political orientation. This means that biology is a possible factor in political orientation but may also mean that the ideology a person identifies with changes a person's ability to perform certain tasks. Many of the studies linking biology to politics remain controversial and unreplicated, although the overall body of evidence is growing.

The Bibi-binary system for numeric notation (in French système Bibi-binaire, or abbreviated "système Bibi") is a hexadecimal numeral system first described in 1968 by singer/mathematician Robert "Boby" Lapointe (1922–1972). At the time, it attracted the attention of André Lichnerowicz, then engaged in studies at the University of Lyon. It found some use in a variety of unforeseen applications: stochastic poetry, stochastic art, colour classification, aleatory music, architectural symbolism, etc.

The notational system directly and logically encodes the binary representations of the digits in a hexadecimal (base sixteen) numeral. In place of the Arabic numerals 0–9 and letters A–F currently used in writing hexadecimal numerals, it presents sixteen newly devised symbols (thus evading any risk of confusion with the decimal system). The graphical and phonetic conception of these symbols is meant to render the use of the Bibi-binary "language" simple and fast.

The description of the language first appeared in Les Cerveaux non-humains ("Non-human brains"), and the system can also be found in Boby Lapointe by Huguette Long Lapointe.

🔗 Books

"Bookland" is the informal name for the Unique Country Code (UCC) prefix allocated in the 1980s for European Article Number (EAN) identifiers of published books, regardless of country of origin, so that the EAN namespace can catalogue books by ISBN rather than maintaining a redundant parallel numbering system. In other words, Bookland is a fictitious country that exists solely in EAN for the purposes of non-geographically cataloguing books in the otherwise geographically keyed EAN coding system.

The Artificio de Juanelo ("Gianello's artifice") was the name of two devices built in Toledo in the 16th century by Juanelo Turriano. They were designed to supply the city with a source of readily available water by lifting it from the Tagus (Tajo) river to the Alcázar. Now in ruins, the precise details of the operation of the devices are unknown, but at the time they were considered engineering wonders.