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In flotation REST, the room contains a tank or pool. The flotation medium consists of a skin-temperature solution of water and Epsom salts at a specific gravity that allows for the patient to float supine without the worry of safety. In fact, to turn over while in the solution requires "major deliberate effort." Fewer ... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Flotation therapy has been academically studied in the US and in Sweden with published results showing reductions of both pain and stress. The relaxed state also involves lowered blood pressure, lowered levels of cortisol, and maximal blood flow. Besides physiological effects, REST seems to have positive effects on wel... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Several differences exist between flotation and chamber REST. For example, with the presence of a medium in flotation REST, the subject has reduced tactile stimulation while experiencing weightlessness. The addition of Epsom salts to attain the desired specific gravity may have a therapeutic effect on hypertonic muscle... | https://en.wikipedia.org/wiki/Sensory_deprivation |
This may not allow the subject to experience the changes in attitudes and thinking that are associated with chamber REST. Additionally, the research questions asked between each technique are different. Chamber REST questions stemmed from research that began in the 1950s and explored a variety of questions about the ne... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Practitioners in this area have explored its utility in the treatment of major psychiatric dysfunctions such as substance abuse. On the contrary, flotation REST was seen as more of a recreational tool as it was tested more for its use with stress-related disorders, pain reduction, and insomnia.Numerous studies have deb... | https://en.wikipedia.org/wiki/Sensory_deprivation |
The statistic of interest, d, is a measure of the size of the treatment effect. For reference, d=0.5 is considered a moderate effect and d=0.8 a large effect. The 19 subjects who underwent chamber REST had d=0.53 and six flotation REST subjects showed d=0.33. Additionally, when examining subjects undergoing REST treatm... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Sensory deprivation has been used to help support arguments by philosophers on how minds work. One example is the floating man argument proposed by Ibn Sīnā, whose primary objective is to affirm the existence of the human soul. | https://en.wikipedia.org/wiki/Sensory_deprivation |
Ibn Sīnā, one of the most important philosophers of the medieval period, investigated the existence of the self and explored the self's nature. Like many others, he proposed an argument to support his claim regarding the relationship between the mind and the body. He based his investigation on the Floating Man argument... | https://en.wikipedia.org/wiki/Sensory_deprivation |
This man is unable to see anything external; his arms and legs are separated from the rest of his body; they do not meet or touch. In other words, the man is experiencing extreme sensory deprivation in order to separate what physical body and any perception of stimuli that a person can experience from what consciousnes... | https://en.wikipedia.org/wiki/Sensory_deprivation |
He will not question that he exists, but he will not be able to affirm if his legs, arms, or internal organs exist. He guarantees that his essence exists, but he will not have awareness of the length or depth of himself. Therefore, in the thought experiment, what the man can affirm to exist is the man's self and what h... | https://en.wikipedia.org/wiki/Sensory_deprivation |
The argument concludes then that since the man can affirm his existence while being subjected to extreme sensory deprivation, his soul is something different from his physical body. His soul is then said to be an immaterial substance separate from his body. This is considered a dualist argument in the philosophy of min... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Dualism presupposes that the world is made up of physical (perceived through the senses), and immaterial (not perceived through the senses) substances.René Descartes was the philosopher who proposed Cartesian dualism, also called substance dualism, since it claims the existence of two kinds of “substances”: mental stat... | https://en.wikipedia.org/wiki/Sensory_deprivation |
The use of REST has been explored in aiding in the cessation of smoking. In studies ranging between 12 months and five years, 25% of REST patients achieved long-term abstinence. REST, when combined with other effective smoking cessation methods (for example: behavior modification) resulted in long-term abstinence of 50... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Comparatively, the use of a nicotine patch alone has a success rate of 5%.Alcoholism has also been the target of research associated with REST. In conjunction with anti-alcohol educational messages, patients who underwent two hours of REST treatment reduced alcohol consumption by 56% in the first two weeks after treatm... | https://en.wikipedia.org/wiki/Sensory_deprivation |
It is, however, possible that this is caused by the placebo effect. In addition, REST has been tested to determine its effect on users of other drugs. A University of Arizona study used chamber REST as a complement to traditional outpatient substance abuse treatment and found that four years later, 43% of the patients ... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Studies have been conducted to test the effect of sensory deprivation on the brain. One study took 19 volunteers, all of whom tested in the lower and upper 20th percentiles on a questionnaire that measures the tendency of healthy people to see things not really there, and placed them in a pitch-black, soundproof booth ... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Many studies have been conducted to understand the main causes of the hallucinations, and considerable evidence has been accumulated indicating that long periods of isolation aren't directly related to the level of experienced hallucinations.Schizophrenics appear to tend to experience fewer hallucinations while in REST... | https://en.wikipedia.org/wiki/Sensory_deprivation |
A study conducted on individuals who underwent REST while under the effects of Phencyclidine (PCP) showed a lower incidence of hallucination in comparison to participants who did not take PCP. The effects of PCP also appeared to be reduced while undergoing REST. The effects PCP has on reducing occurrences of hallucinat... | https://en.wikipedia.org/wiki/Sensory_deprivation |
Sensory deprivation has been used to disorientate subjects during interrogation, brainwashing, and torture. In particular, the five techniques of wall-standing; hooding; subjection to noise; deprivation of sleep; deprivation of food and drink were used by the security forces in Northern Ireland in the early 1970s. Afte... | https://en.wikipedia.org/wiki/Sensory_deprivation |
on Hum. Rts. 512, 748, 788-94 (European Commission of Human Rights)). | https://en.wikipedia.org/wiki/Sensory_deprivation |
The Commission stated that it "considered the combined use of the five methods to amount to torture." This consideration was overturned on appeal, when in 1978 the European Court of Human Rights (ECtHR) examined the United Nations' definition of torture. The court subsequently ruled that the five techniques "did not oc... | https://en.wikipedia.org/wiki/Sensory_deprivation |
P. Solomon et al. (eds.) (1961). Sensory deprivation. | https://en.wikipedia.org/wiki/Sensory_deprivation |
Harvard University Press. Marvin Zuckerman, Nathan Cohen (1964). "Sources of Reports of Visual Auditory Sensations in perceptual-isolation experiments". | https://en.wikipedia.org/wiki/Sensory_deprivation |
Psychological Bulletin, July 1964, 62, pp. 1–20. L. Goldberger (1966). | https://en.wikipedia.org/wiki/Sensory_deprivation |
"Experimental isolation: An overview". American Journal of Psychiatry 122, 774–782. J. Zubek (ed.) | https://en.wikipedia.org/wiki/Sensory_deprivation |
(1969). Sensory deprivation: Fifteen years of research. Appleton Century Crofts. | https://en.wikipedia.org/wiki/Sensory_deprivation |
European Court of Human Rights (1978). Ireland v. the United Kingdom – January 18, 1978. Dirk van Dierendonck & Jan te Nijenhuis (2005). | https://en.wikipedia.org/wiki/Sensory_deprivation |
"Flotation restricted environmental stimulation therapy (REST) as a stress-management tool: A meta-analysis". Psychology and Health, June 2005, 20(3), pp. 405–412. | https://en.wikipedia.org/wiki/Sensory_deprivation |
P. R. Corlett, C. D. Frith, P. C. Fletcher (2009). "From drugs to deprivation: a Bayesian framework for understanding models of psychosis". Psychopharmacology, November 2009, 206(4), pp. 515–530. | https://en.wikipedia.org/wiki/Sensory_deprivation |
A round barn is a historic barn design that could be octagonal, polygonal, or circular in plan. Though round barns were not as popular as some other barn designs, their unique shape makes them noticeable. The years from 1880 to 1920 represent the height of round barn construction. Round barn construction in the United ... | https://en.wikipedia.org/wiki/Round_barn |
The first, the octagonal era, spanned from 1850 to 1900. The second, the true circular era, spanned from 1889 to 1936. The overlap meant that round barns of both types, polygonal and circular, were built during the latter part of the nineteenth century. Numerous round barns in the United States are listed on the Nation... | https://en.wikipedia.org/wiki/Round_barn |
Round barns date to the 18th and early 19th century. George Washington designed and built a sixteen-sided threshing barn at his Dogue Run Farm in Fairfax County, Virginia in 1793. The first truly round barn in North America was constructed in 1826 at Hancock Shaker Village. A few other round barns appeared on the Ameri... | https://en.wikipedia.org/wiki/Round_barn |
It was between 1880 and 1920 that round barns were most popular in the United States, especially in the Midwest. The rise in popularity and the promotion of round barns occurred surrounding the new focus on efficiency. The circular shape has a greater volume-to-surface ratio than a square barn. | https://en.wikipedia.org/wiki/Round_barn |
Regardless of size, this made round barns cheaper to construct than similar-sized square or rectangular barns because they required less materials. The structural stability is also enhanced over that of a typical quadrilaterally shaped barn. | https://en.wikipedia.org/wiki/Round_barn |
Simplified construction lacking elaborate truss systems for the arched roof was also seen as an advantage. In the Midwest, particularly, the buildings were thought more resilient against prairie thunderstorms. The interior layout of round barns was promoted as more efficient, since farmers could work in a continuous di... | https://en.wikipedia.org/wiki/Round_barn |
In the days before mechanization, labor-saving features were a big selling point. The interest in round barns spread to California in the later 19th century and several were built there. Santa Rosa, California is home to the De Turk Round Barn, a well-preserved example built in the late 1870s by local settler and busin... | https://en.wikipedia.org/wiki/Round_barn |
The round barn never caught on as a standard barn, as some of those pushing the progressive, efficiency-based agricultural methods had hoped. The spread of machinery, especially with the Rural Electrification program, eliminated the advantages of labor-saving designs that were more complicated to build, and the popular... | https://en.wikipedia.org/wiki/Round_barn |
The "Octagonal Era" of round barn design stretched from about 1850 until 1900. Round barns, such as Washington's, were often multi sided in their earliest incarnations. Multi-sided round barns came in a variety of polygonal shapes, including layouts of six, eight, nine, ten, twelve, fourteen and sixteen sides. Polygona... | https://en.wikipedia.org/wiki/Round_barn |
The "True Circular Era" of round barn construction spanned from 1889 to 1936, overlapping the octagonal era and finally dwindling out as round barns fell out of popularity. True circular round barns began to rise as improvements in construction techniques made their design more practical. As balloon framing, circular s... | https://en.wikipedia.org/wiki/Round_barn |
By the 1920s round barn construction had begun to decline in some locations. In Illinois, the popularity of round barns was in part due to the University of Illinois round barns, and round barn construction had tapered off considerably. Several reasons have been given for the decline in the popularity of round barn des... | https://en.wikipedia.org/wiki/Round_barn |
Designed in a distinctive circular shape, many of these barns were meant to take advantage of gravity to move hay from the loft to the cow stable below. In many cases, a silo was constructed to rise up through the round barn's center. The round barn was promoted as a labor-saving design by agricultural colleges as a pr... | https://en.wikipedia.org/wiki/Round_barn |
They also tend to be wood-sided while the later round barns are more often faced with brick or glazed tile. The interior design of round barns shifted as well. The early round barns had cattle stanchions on the first floor with the whole of the loft used for hay and feed storage. | https://en.wikipedia.org/wiki/Round_barn |
Later barns possessed a central space which rose up from the ground level through the entire building. The cattle stanchions in this variation of round barn were arranged around a circular manger on the lower level. | https://en.wikipedia.org/wiki/Round_barn |
Above the stanchion level a circular wagon drive allowed hay to be unloaded into the central mow as the wagon circled the perimeter. The final stage of interior design in round barns included a storage silo through the center of the structures. These were not really added until silos became fixtures of American farms. ... | https://en.wikipedia.org/wiki/Round_barn |
It is known that prominent agricultural colleges began to promote the design technique as round barns came to prominence. However, the provider of the initial impetus is the subject of some debate. In 1848 Orson Fowler published A Home For All: Of the Gravel Wall and Octagon Mode of Building, extolling the virtues of t... | https://en.wikipedia.org/wiki/Round_barn |
The book generated a flurry of octagonal home construction, especially in the New England and Middle Atlantic states. Some researchers have linked the earliest round barn constructions with Fowler's popular book because so many of the early round barns assumed the octagonal shape.Other historians discount Fowler's infl... | https://en.wikipedia.org/wiki/Round_barn |
He noted that the octagon had ceased to be the basis for building constructions by the Civil War. In Indiana, for example, 219 round barns were constructed between 1850 and 1936; of those, 67 were polygonal, including 17 eight-sided barns built after 1900.An old belief that the barns were round to keep the devil from h... | https://en.wikipedia.org/wiki/Round_barn |
The Agricultural Experiment Station Bulletin coupled with an article by H.C. Crouch touting round barns in the Illinois Agriculturalist led to the construction of round barns across the state. Anecdotal evidence of the impact of the University of Illinois round barns can be collected from farmers today. Stories about f... | https://en.wikipedia.org/wiki/Round_barn |
There are about 20 surviving historic round barns in Canada. The United States has several hundred. In Europe, round barns are common, but there are some notable ones much older than those in North America. | https://en.wikipedia.org/wiki/Round_barn |
Michael Billig (born 1947) is a British academic. He is Emeritus Professor of Social Sciences at Loughborough University, working principally in contemporary social psychology although much of his work crosses disciplinary boundaries in the social sciences. | https://en.wikipedia.org/wiki/Michael_Billig |
Billig was born in 1947 to a Jewish family from London and he went to the University of Bristol to study Philosophy and Psychology. While at Bristol he was taught by Professor Henri Tajfel, a renowned social psychologist, who was to have an enduring and profound influence on Billig. After Billig obtained his undergradu... | https://en.wikipedia.org/wiki/Michael_Billig |
As Tajfel's research assistant, Billig's task was to help design, conduct and analyse the first so-called minimal group experiments which examined how people will favour members of their own group and discriminate against members of an outgroup, even when these groups were deliberately artificial and meaningless. These... | https://en.wikipedia.org/wiki/Michael_Billig |
He wrote a series of important books exploring these topics. His Social Psychology and Intergroup Relations (1976) offered a critique of orthodox approaches to the study prejudice in psychology and criticised approaches that concentrated on individuals and neglected group contexts. | https://en.wikipedia.org/wiki/Michael_Billig |
Billig became interested in studying the far-right and realised that an experimental approach would be inappropriate. Fascists (1978) revealed the classic fascist and antisemitic ideology underlying the UK's National Front at a time when it was bidding for political legitimacy and electoral success. Billig also wrote a... | https://en.wikipedia.org/wiki/Michael_Billig |
In this pamphlet he exposed links between far-right groups and some psychologists who were seeking to prove that there were biological differences between the intellectual capacities of different so-called 'races'. The pamphlet was extended into a full-length book, L'Internationale Raciste (1981), which also looked at ... | https://en.wikipedia.org/wiki/Michael_Billig |
In the 1980s Billig's focus shifted to everyday thinking and the relationship between ideology and common sense (Ideology and Social Psychology, 1982). This strand of work became more pronounced after he moved to Loughborough University in 1985 to become professor of Social Science in the multidisciplinary department o... | https://en.wikipedia.org/wiki/Michael_Billig |
For example, he suggests that attitudes are best understood not as individual positions on topics, but as rhetorical stances in argumentative contexts. This perspective was introduced in his book Arguing and Thinking (1987; 2nd Edition, 1996). Ideological Dilemmas (1988), which was collectively written with his Loughbo... | https://en.wikipedia.org/wiki/Michael_Billig |
At Loughborough he was a founding member of the influential Discourse and Rhetoric Group, which included figures such as Derek Edwards and Jonathan Potter. The group, which stressed that psychologists should examine in detail the way language is used, was central to the creation of discursive psychology. One feature of... | https://en.wikipedia.org/wiki/Michael_Billig |
For example, he studied views about the British royalty in Talking of the Royal Family (1998, 2nd Edition). Banal Nationalism, probably Billig's most well known, and certainly his most cited book, threw new light on the topic of nationalism, by examining the small and largely unnoticed details of the ways that nation-s... | https://en.wikipedia.org/wiki/Michael_Billig |
His Freudian Repression (1999) reinterpreted psychoanalytic theory in terms of conversation, while Laughter and Ridicule (2005) suggested that humour, in the form of ridicule, had an important, disciplinary function in society. The Politics and Rhetoric of Political Celebration, written in collaboration with Cristina M... | https://en.wikipedia.org/wiki/Michael_Billig |
The Hidden Roots of Critical Psychology (2008) sought to expand conventional histories of psychology by arguing that in the eighteenth century the Third Earl of Shaftesbury and Thomas Reid formulated ideas about the mind that today are being proposed by critical psychologists. Rock'n'Roll Jews (2000) focused on the cru... | https://en.wikipedia.org/wiki/Michael_Billig |
Learn to Write Badly (2013) criticised social scientists for using too much jargon. Billig argued that, when it comes to describing human actions, heavy technical nouns are, in fact, often less precise than ordinary language. He developed these themes in More Examples, Less Theory (2019), which claims that psychologist... | https://en.wikipedia.org/wiki/Michael_Billig |
Billig suggests that researchers should try to examine real-life examples directly, rather than through the oversimplifying lens of theory. In this book, Billig proposed Marie Jahoda as the example that psychologists today should try to follow on account of her clear writing, social commitment, scepticism of theory and... | https://en.wikipedia.org/wiki/Michael_Billig |
2010: awarded Distinguished Contribution to Social Psychology Award by the Social Psychology Section of the British Psychological Society 2020: elected a Fellow of the British Academy | https://en.wikipedia.org/wiki/Michael_Billig |
His aunt was the doctor Hannah Billig, MBE. | https://en.wikipedia.org/wiki/Michael_Billig |
Tŷ unnos (pl. : tai unnos; English: one night house, also hafodunnos) is an old Welsh tradition that has parallels in other folk traditions in other areas of the British Isles. It was believed by some that if a person could build a house on common land in one night, the land then belonged to them as a freehold. There a... | https://en.wikipedia.org/wiki/Tŷ_unnos |
From a period spanning the seventeenth to the beginning of the nineteenth centuries, the expansion of the Welsh population combined with poverty brought about a series of incidents of squatting on isolated patches of land in the most rural parts of Wales. The practice arose because of the pressure of the lack of land d... | https://en.wikipedia.org/wiki/Tŷ_unnos |
Tŷ unnos has no status in English common law (the legal code which applied to England and Wales in this period), although there is some tradition of legal discussion about the point at which land occupied by squatters without title may be regarded as a legitimate possession. This legendary belief may bear some relation... | https://en.wikipedia.org/wiki/Tŷ_unnos |
The customary practice has no foundation in the Common Law regarding land usage as it applies in England and Wales. Many localities in Wales and England have a house or houses which may be identified as a one night house in local folklore. These may in fact be properties that were originally built by squatters and may ... | https://en.wikipedia.org/wiki/Tŷ_unnos |
The Ugly House (Tŷ Hyll) is a celebrated example in Snowdonia.Many of these legends seem to be passed on in ignorance of the broader tradition of the one night house and may feature picturesque details based on variants of the traditions noted above. These legends generally take the form of a prominent member of local ... | https://en.wikipedia.org/wiki/Tŷ_unnos |
A good general account of one night house traditions is provided in the book Cotters and Squatters, by the British anarchist and writer on housing issues, Colin Ward. Ward considers the one night house tradition in the context of squatting and other informal systems of occupying and using land and relates accounts from... | https://en.wikipedia.org/wiki/Tŷ_unnos |
Very little is known in detail about the building of these structures, their numbers or inhabitants, and no accurate representations survive. Most Tai Unnos (pl.) were originally made of turf and soil, with a roughly thatched roof. Once established, the walls were often replaced with local materials, including clay and... | https://en.wikipedia.org/wiki/Tŷ_unnos |
An experimental construction in Carmarthenshire in 2006 demonstrated that a rudimentary structure could be assembled quickly. The squatters may not have depended exclusively on agriculture and in some areas may have worked in quarries and mines. This development led to dispersed settlement patterns seen in the Welsh la... | https://en.wikipedia.org/wiki/Tŷ_unnos |
Materials from early stages of construction may have been replaced by higher quality timber and slates, available via the new railways. Single storey Tŷ Unnos cottages were modified by raising the roofs and enlarging the windows.The most recent known tŷ unnos was built in 1882. Four brothers built it in Flintshire. Oli... | https://en.wikipedia.org/wiki/Tŷ_unnos |
The "ty unnos" concept has been used as an inspiration for low-cost modular housing systems. The Welsh woodland charity called Coed Cymru used "Ty Unnos" as a name for a house design using local materials. In 2009, they were invited to show the design in Washington, D.C. as part of the 2009 Smithsonian Folklife Festiva... | https://en.wikipedia.org/wiki/Tŷ_unnos |
Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest. | https://en.wikipedia.org/wiki/Gravimetry |
Gravity is usually measured in units of acceleration. In the SI system of units, the standard unit of acceleration is 1 metre per second squared (abbreviated as m/s2). Other units include the cgs gal (sometimes known as a galileo, in either case with symbol Gal), which equals 1 centimetre per second squared, and the g ... | https://en.wikipedia.org/wiki/Gravimetry |
An instrument used to measure gravity is known as a gravimeter. For a small body, general relativity predicts gravitational effects indistinguishable from the effects of acceleration by the equivalence principle. Thus, gravimeters can be regarded as special-purpose accelerometers. Many weighing scales may be regarded a... | https://en.wikipedia.org/wiki/Gravimetry |
In one common form, a spring is used to counteract the force of gravity pulling on an object. The change in length of the spring may be calibrated to the force required to balance the gravitational pull. The resulting measurement may be made in units of force (such as the newton), but is more commonly made in units of ... | https://en.wikipedia.org/wiki/Gravimetry |
Researchers use more sophisticated gravimeters when precise measurements are needed. When measuring the Earth's gravitational field, measurements are made to the precision of microgals to find density variations in the rocks making up the Earth. Several types of gravimeters exist for making these measurements, includin... | https://en.wikipedia.org/wiki/Gravimetry |
These measurements are used to define gravity anomalies. Besides precision, stability is also an important property of a gravimeter, as it allows the monitoring of gravity changes. These changes can be the result of mass displacements inside the Earth, or of vertical movements of the Earth's crust on which measurements... | https://en.wikipedia.org/wiki/Gravimetry |
The study of gravity changes belongs to geodynamics. The majority of modern gravimeters use specially-designed metal or quartz zero-length springs to support the test mass. Zero-length springs do not follow Hooke's law; instead they have a force proportional to their length. | https://en.wikipedia.org/wiki/Gravimetry |
The special property of these springs is that the natural resonant period of oscillation of the spring–mass system can be made very long – approaching a thousand seconds. This detunes the test mass from most local vibration and mechanical noise, increasing the sensitivity and utility of the gravimeter. Quartz and metal... | https://en.wikipedia.org/wiki/Gravimetry |
The test mass is sealed in an air-tight container so that tiny changes of barometric pressure from blowing wind and other weather do not change the buoyancy of the test mass in air. Spring gravimeters are, in practice, relative instruments which measure the difference in gravity between different locations. A relative ... | https://en.wikipedia.org/wiki/Gravimetry |
Absolute gravimeters provide such measurements by determining the gravitational acceleration of a test mass in vacuum. A test mass is allowed to fall freely inside a vacuum chamber and its position is measured with a laser interferometer and timed with an atomic clock. The laser wavelength is known to ±0.025 ppb and th... | https://en.wikipedia.org/wiki/Gravimetry |
Great care must be taken to minimize the effects of perturbing forces such as residual air resistance (even in vacuum), vibration, and magnetic forces. Such instruments are capable of an accuracy of about two parts per billion or 0.002 mGal and reference their measurement to atomic standards of length and time. Their p... | https://en.wikipedia.org/wiki/Gravimetry |
However, absolute instruments are somewhat larger and significantly more expensive than relative spring gravimeters, and are thus relatively rare. Gravimeters have been designed to mount in vehicles, including aircraft (note the field of aerogravity), ships and submarines. | https://en.wikipedia.org/wiki/Gravimetry |
These special gravimeters isolate acceleration from the movement of the vehicle and subtract it from measurements. The acceleration of the vehicles is often hundreds or thousands of times stronger than the changes being measured. A gravimeter (the Lunar Surface Gravimeter) deployed on the surface of the Moon during the... | https://en.wikipedia.org/wiki/Gravimetry |
Gravimeters for measuring the Earth's gravity as precisely as possible are getting smaller and more portable. A common type measures the acceleration of small masses free falling in a vacuum, when the accelerometer is firmly attached to the ground. The mass includes a retroreflector and terminates one arm of a Michelso... | https://en.wikipedia.org/wiki/Gravimetry |
A more recent development is a "rise and fall" version that tosses the mass upward and measures both upward and downward motion. This allows cancellation of some measurement errors; however, "rise and fall" gravimeters are not yet in common use. Absolute gravimeters are used in the calibration of relative gravimeters, ... | https://en.wikipedia.org/wiki/Gravimetry |
Atom interferometric and atomic fountain methods are used for precise measurement of the Earth's gravity, and atomic clocks and purpose-built instruments can use time dilation (also called general relativistic) measurements to track changes in the gravitational potential and gravitational acceleration on the Earth. The... | https://en.wikipedia.org/wiki/Gravimetry |
The most common gravimeters are spring-based. They are used in gravity surveys over large areas for establishing the figure of the geoid over those areas. They are basically a weight on a spring, and by measuring the amount by which the weight stretches the spring, local gravity can be measured. However, the strength o... | https://en.wikipedia.org/wiki/Gravimetry |
The superconducting gravimeter achieves sensitivities of 10–11 m·s−2 (one nanogal), approximately one trillionth (10−12) of the Earth surface gravity. In a demonstration of the sensitivity of the superconducting gravimeter, Virtanen (2006), describes how an instrument at Metsähovi, Finland, detected the gradual increas... | https://en.wikipedia.org/wiki/Gravimetry |
This is roughly ±1000 nm/s2 (nanometers per second squared) at most locations. "SGs", as they are called, can detect and characterize Earth tides, changes in the density of the atmosphere, the effect of changes in the shape of the surface of the ocean, the effect of the atmosphere's pressure on the Earth, changes in th... | https://en.wikipedia.org/wiki/Gravimetry |
When operated to report acceleration, they are useful gravimeters. Because they have three axes, it is possible to solve for their position and orientation, by either tracking the arrival time and pattern of seismic waves from earthquakes, or by referencing them to the Sun and Moon tidal gravity. Recently, the SGs, and... | https://en.wikipedia.org/wiki/Gravimetry |
These signals arrive at the gravimeter at the speed of light, so have the potential to improve earthquake early warning methods. There is some activity to design purpose-built gravimeters of sufficient sensitivity and bandwidth to detect these prompt gravity signals from earthquakes. Not just the magnitude 7+ events, b... | https://en.wikipedia.org/wiki/Gravimetry |
Newer MEMS gravimeters, atom gravimeters – MEMS gravimeters offer the potential for low-cost arrays of sensors. MEMS gravimeters are currently variations on spring type accelerometers where the motions of a tiny cantilever or mass are tracked to report acceleration. Much of the research is focused on different methods ... | https://en.wikipedia.org/wiki/Gravimetry |
In Atom gravimeters, the mass is a collection of atoms. For a given restoring force, the central frequency of the instrument is often given by ω = 2 π × Frequency = ForceConstant Effective Mass {\displaystyle \omega =2\pi \times {\text{Frequency}}={\sqrt {{\text{ForceConstant}} \over {\text{Effective Mass}}}}} (in radi... | https://en.wikipedia.org/wiki/Gravimetry |
g(X,t) = a + b v/m + k x/m + constant/m + higher derivatives of the restoring forcePrecise GPS stations can be operated as gravimeters since they are increasingly measuring three axis positions over time, which, when differentiated twice, give an acceleration signal. The satellite borne gravimeters GOCE, GRACE, are mos... | https://en.wikipedia.org/wiki/Gravimetry |
They yield detailed information about the Earth's time varying gravity field. The spherical harmonic gravitational potential models are slowly improving in both spatial and temporal resolution. Taking the gradient of the potentials gives estimate of local acceleration which are what is measured by the gravimeter arrays... | https://en.wikipedia.org/wiki/Gravimetry |
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