title: Biodiversity

text: National park is a large natural or near natural areas set aside to protect large-scale ecological processes, which also provide a foundation for environmentally and culturally compatible, spiritual, scientific, educational, recreational and visitor opportunities. These areas are selected by governments or private organizations to protect natural biodiversity along with its underlying ecological structure and supporting environmental processes, and to promote education and recreation. The International Union for Conservation of Nature (IUCN), and its World Commission on Protected Areas (WCPA), has defined "National Park" as its Category II type of protected areas.


title: Biodiversity

text: National parks are usually owned and managed by national or state governments. In some cases, a limit is placed on the number of visitors permitted to enter certain fragile areas. Designated trails or roads are created. The visitors are allowed to enter only for study, cultural and recreation purposes. Forestry operations, grazing of animals and hunting of animals are regulated and the exploitation of habitat or wildlife is banned.


title: Biodiversity

text: There is an estimated 726 million ha of forest in protected areas worldwide. Of the six major world regions, South America has the highest share of forests in protected areas, 31 percent.


title: Biodiversity

text: The forests play a vital role in harboring more than 45,000 floral and 81,000 faunal species of which 5150 floral and 1837 faunal species are endemic. In addition, there are 60,065 different tree species in the world. Plant and animal species confined to a specific geographical area are called endemic species. In forest reserves, rights to activities like hunting and grazing are sometimes given to communities living on the fringes of the forest, who sustain their livelihood partially or wholly from forest resources or products. The unclassed forests cover 6.4 percent of the total forest area and they are marked by the following characteristics:


title: Biodiversity

text: In zoological parks or zoos, live animals are kept for public recreation, education and conservation purposes. Modern zoos offer veterinary facilities, provide opportunities for threatened species to breed in captivity and usually build environments that simulate the native habitats of the animals in their care. Zoos play a major role in creating awareness about the need to conserve nature.


title: Biodiversity

text: In botanical gardens, plants are grown and displayed primarily for scientific and educational purposes. They consist of a collection of living plants, grown outdoors or under glass in greenhouses and conservatories. Also, a botanical garden may include a collection of dried plants or herbarium and such facilities as lecture rooms, laboratories, libraries, museums and experimental or research plantings.


title: Biodiversity

text: Focusing on limited areas of higher potential biodiversity promises greater immediate return on investment than spreading resources evenly or focusing on areas of little diversity but greater interest in biodiversity.


title: Biodiversity

text: A second strategy focuses on areas that retain most of their original diversity, which typically require little or no restoration. These are typically non-urbanized, non-agricultural areas. Tropical areas often fit both criteria, given their natively high diversity and relative lack of development.


title: Biodiversity

text: In September 2020 scientists reported that "immediate efforts, consistent with the broader sustainability agenda but of unprecedented ambition and coordination, could enable the provision of food for the growing human population while reversing the global terrestrial biodiversity trends caused by habitat conversion" and recommend measures such as for addressing drivers of land-use change, and for increasing the extent of land under conservation management, efficiency in agriculture and the shares of plant-based diets.


title: Biodiversity

text: Citizen science, also known as public participation in scientific research, has been widely used in environmental sciences and is particularly popular in a biodiversity-related context. It has been used to enable scientists to involve the general public in biodiversity research, thereby enabling the scientists to collect data that they would otherwise not have been able to obtain. An online survey of 1,160 CS participants across 63 biodiversity citizen science projects in Europe, Australia and New Zealand reported positive changes in (a) content, process and nature of science knowledge, (b) skills of science inquiry, (c) self-efficacy for science and the environment, (d) interest in science and the environment, (e) motivation for science and the environment and (f) behaviour towards the environment.


title: Biodiversity

text: Volunteer observers have made significant contributions to on-the-ground knowledge about biodiversity, and recent improvements in technology have helped increase the flow and quality of occurrences from citizen sources. A 2016 study published in Biological Conservation registers the massive contributions that citizen scientists already make to data mediated by the Global Biodiversity Information Facility (GBIF). Despite some limitations of the dataset-level analysis, it's clear that nearly half of all occurrence records shared through the GBIF network come from datasets with significant volunteer contributions. Recording and sharing observations are enabled by several global-scale platforms, including iNaturalist and eBird.


title: Biodiversity

text: Global agreements such as the Convention on Biological Diversity, give "sovereign national rights over biological resources" (not property). The agreements commit countries to "conserve biodiversity", "develop resources for sustainability" and "share the benefits" resulting from their use. Biodiverse countries that allow bioprospecting or collection of natural products, expect a share of the benefits rather than allowing the individual or institution that discovers/exploits the resource to capture them privately. Bioprospecting can become a type of biopiracy when such principles are not respected.


title: Biodiversity

text: Sovereignty principles can rely upon what is better known as Access and Benefit Sharing Agreements (ABAs). The Convention on Biodiversity implies informed consent between the source country and the collector, to establish which resource will be used and for what and to settle on a fair agreement on benefit sharing.


title: Biodiversity

text: In May 2020, the European Union published its Biodiversity Strategy for 2030. The biodiversity strategy is an essential part of the climate change mitigation strategy of the European Union. From the 25% of the European budget that will go to fight climate change, large part will go to restore biodiversity and nature based solutions.


title: Biodiversity

text: Approximately half of the global GDP depend on nature. In Europe many parts of the economy that generate trillions of euros per year depend on nature. The benefits of Natura 2000 alone in Europe are €200 – €300 billion per year.


title: Biodiversity

text: Uniform approval for use of biodiversity as a legal standard has not been achieved, however. Bosselman argues that biodiversity should not be used as a legal standard, claiming that the remaining areas of scientific uncertainty cause unacceptable administrative waste and increase litigation without promoting preservation goals.


title: Biodiversity

text: India passed the Biological Diversity Act in 2002 for the conservation of biological diversity in India. The Act also provides mechanisms for equitable sharing of benefits from the use of traditional biological resources and knowledge.


title: Biodiversity

text: Less than 1% of all species that have been described have been studied beyond noting their existence. The vast majority of Earth's species are microbial. Contemporary biodiversity physics is "firmly fixated on the visible [macroscopic] world". For example, microbial life is metabolically and environmentally more diverse than multicellular life (see e.g., extremophile). "On the tree of life, based on analyses of small-subunit ribosomal RNA, visible life consists of barely noticeable twigs. The inverse relationship of size and population recurs higher on the evolutionary ladder—to a first approximation, all multicellular species on Earth are insects". Insect extinction rates are high—supporting the Holocene extinction hypothesis.


title: Biodiversity

text: The number of morphological attributes that can be scored for diversity study is generally limited and prone to environmental influences; thereby reducing the fine resolution required to ascertain the phylogenetic relationships. DNA based markers- microsatellites otherwise known as "simple sequence repeats" (SSR) were therefore used for the diversity studies of certain species and their wild relatives.


title: Biodiversity

text: In the case of cowpea, a study conducted to assess the level of genetic diversity in cowpea germplasm and related wide species, where the relatedness among various taxa was compared, primers useful for classification of taxa identified, and the origin and phylogeny of cultivated cowpea classified show that SSR markers are useful in validating with species classification and revealing the center of diversity.


title: Humidity

text: Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.


title: Humidity

text: Humidity depends on the temperature and pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is the dew point. The amount of water vapor needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 g of water per cubic metre of air at , but only 8 g of water per cubic metre of air at .


title: Humidity

text: Three primary measurements of humidity are widely employed: absolute, relative, and specific. Absolute humidity is expressed as either mass of water vapor per volume of moist air (in grams per cubic metre) or as mass of water vapor per mass of dry air (usually in grams per kilogram). Relative humidity, often expressed as a percentage, indicates a present state of absolute humidity relative to a maximum humidity given the same temperature. Specific humidity is the ratio of water vapor mass to total moist air parcel mass.


title: Humidity

text: Humidity plays an important role for surface life. For animal life dependent on perspiration (sweating) to regulate internal body temperature, high humidity impairs heat exchange efficiency by reducing the rate of moisture evaporation from skin surfaces. This effect can be calculated using a heat index table, also known as a humidex.


title: Humidity

text: The notion of air "holding" water vapor or being "saturated" by it is often mentioned in connection with the concept of relative humidity. This, however, is misleading—the amount of water vapor that enters (or can enter) a given space at a given temperature is almost independent of the amount of air (nitrogen, oxygen, etc.) that is present. Indeed, a vacuum has approximately the same equilibrium capacity to hold water vapor as the same volume filled with air; both are given by the equilibrium vapor pressure of water at the given temperature. There is a very small difference described under "Enhancement factor" below, which can be neglected in many calculations unless great accuracy is required.


title: Humidity

text: Absolute humidity is the total mass of water vapor present in a given volume or mass of air. It does not take temperature into consideration. Absolute humidity in the atmosphere ranges from near zero to roughly per cubic metre when the air is saturated at .


title: Humidity

text: Absolute humidity is the mass of the water vapor formula_1, divided by the volume of the air and water vapor mixture formula_2, which can be expressed as:


title: Humidity

text: The absolute humidity changes as air temperature or pressure changes, if the volume is not fixed. This makes it unsuitable for chemical engineering calculations, e.g. in drying, where temperature can vary considerably. As a result, absolute humidity in chemical engineering may refer to mass of water vapor per unit mass of dry air, also known as the "humidity ratio" or "mass mixing ratio" (see "specific humidity" below), which is better suited for heat and mass balance calculations. Mass of water per unit volume as in the equation above is also defined as "volumetric humidity". Because of the potential confusion, British Standard BS 1339 suggests avoiding the term "absolute humidity". Units should always be carefully checked. Many humidity charts are given in g/kg or kg/kg, but any mass units may be used.


title: Humidity

text: The field concerned with the study of physical and thermodynamic properties of gas–vapor mixtures is named psychrometrics.


title: Humidity

text: The relative humidity formula_4 or formula_5 of an air-water mixture is defined as the ratio of the partial pressure of water vapor formula_6 in the mixture to the equilibrium vapor pressure of water formula_7 over a flat surface of pure water at a given temperature:


title: Humidity

text: In other words, relative humidity is the ratio of "how much water vapour is in the air" and "how much water vapour the air could potentially contain" at a given temperature. It varies with the temperature of the air: colder air can hold less vapour. So changing the temperature of air can change the relative humidity, even when the absolute humidity remains constant.


title: Humidity

text: Chilling air increases the relative humidity, and can cause the water vapour to condense (if the relative humidity rises over 100%, the dew point). Likewise, warming air decreases the relative humidity. Warming some air containing a fog may cause that fog to evaporate, as the air between the water droplets becomes more able to hold water vapour.


title: Humidity

text: Relative humidity only considers the invisible water vapour. Mists, clouds, fogs and aerosols of water do not count towards the measure of relative humidity of the air, although their presence is an indication that a body of air may be close to the dew point.


title: Humidity

text: Relative humidity is normally expressed as a percentage; a higher percentage means that the air–water mixture is more humid. At 100% relative humidity, the air is saturated and is at its dew point. In the absence of a foreign body on which droplets or crystals can nucleate, the relative humidity can exceed 100%, in which case the air is said to be supersaturated. Introduction of some particles or a surface to a body of air above 100% relative humidity will allow condensation or ice to form on those nuclei, thereby removing some of the vapour and lowering the humidity.


title: Humidity

text: Relative humidity is an important metric used in weather forecasts and reports, as it is an indicator of the likelihood of precipitation, dew, or fog. In hot summer weather, a rise in relative humidity increases the apparent temperature to humans (and other animals) by hindering the evaporation of perspiration from the skin. For example, according to the "heat index", a relative humidity of 75% at air temperature of would feel like 83.6 °F ±1.3 °F (28.7 °C ±0.7 °C).


title: Humidity

text: "Specific humidity" (or moisture content) is the ratio of the mass of water vapor to the total mass of the air parcel. Specific humidity is approximately equal to the mixing ratio, which is defined as the ratio of the mass of water vapor in an air parcel to the mass of "dry" air for the same parcel. As temperature decreases, the amount of water vapor needed to reach saturation also decreases. As the temperature of a parcel of air becomes lower it will eventually reach the point of saturation without adding or losing water mass.


title: Humidity

text: The term "relative humidity" is reserved for systems of water vapor in air. The term "relative saturation" is used to describe the analogous property for systems consisting of a condensable phase other than water in a non-condensable phase other than air.


title: Humidity

text: A device used to measure humidity of air is called a psychrometer or hygrometer. A humidistat is a humidity-triggered switch, often used to control a dehumidifier.


title: Humidity

text: The humidity of an air and water vapor mixture is determined through the use of psychrometric charts if both the dry bulb temperature ("T") and the wet bulb temperature ("T") of the mixture are known. These quantities are readily estimated by using a sling psychrometer.


title: Humidity

text: There are several empirical formulas that can be used to estimate the equilibrium vapor pressure of water vapor as a function of temperature. The Antoine equation is among the least complex of these, having only three parameters ("A", "B", and "C"). Other formulas, such as the Goff–Gratch equation and the Magnus–Tetens approximation, are more complicated but yield better accuracy.


title: Humidity

text: where formula_10 is the dry-bulb temperature expressed in degrees Celsius (°C), formula_11 is the absolute pressure expressed in millibars, and formula_12 is the equilibrium vapor pressure expressed in millibars. Buck has reported that the maximal relative error is less than 0.20% between when this particular form of the generalized formula is used to estimate the equilibrium vapor pressure of water.


title: Humidity

text: There are various devices used to measure and regulate humidity. Calibration standards for the most accurate measurement include the gravimetric hygrometer, chilled mirror hygrometer, and electrolytic hygrometer. The gravimetric method, while the most accurate, is very cumbersome. For fast and very accurate measurement the chilled mirror method is effective. For process on-line measurements, the most commonly used sensors nowadays are based on capacitance measurements to measure relative humidity, frequently with internal conversions to display absolute humidity as well. These are cheap, simple, generally accurate and relatively robust. All humidity sensors face problems in measuring dust-laden gas, such as exhaust streams from clothes dryers.


title: Humidity

text: Humidity is also measured on a global scale using remotely placed satellites. These satellites are able to detect the concentration of water in the troposphere at altitudes between . Satellites that can measure water vapor have sensors that are sensitive to infrared radiation. Water vapor specifically absorbs and re-radiates radiation in this spectral band. Satellite water vapor imagery plays an important role in monitoring climate conditions (like the formation of thunderstorms) and in the development of weather forecasts.


title: Humidity

text: Humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature. Therefore, when applying more pressure to a gas saturated with water, all components will initially decrease in volume approximately according to the "ideal gas law". However, some of the water will condense until returning to almost the same humidity as before, giving the resulting total volume deviating from what the ideal gas law predicted. Conversely, decreasing temperature would also make some water condense, again making the final volume deviate from predicted by the ideal gas law. Therefore, gas volume may alternatively be expressed as the dry volume, excluding the humidity content. This fraction more accurately follows the ideal gas law. On the contrary the saturated volume is the volume a gas mixture would have if humidity was added to it until saturation (or 100% relative humidity).


title: Humidity

text: Humid air is less dense than dry air because a molecule of water (M ≈ 18 u) is less massive than either a molecule of nitrogen (M ≈ 28) or a molecule of oxygen (M ≈ 32). About 78% of the molecules in dry air are nitrogen (N). Another 21% of the molecules in dry air are oxygen (O). The final 1% of dry air is a mixture of other gases.


title: Humidity

text: For any gas, at a given temperature and pressure, the number of molecules present in a particular volume is constant. So when water molecules (vapor) are introduced into that volume of dry air, the number of air molecules in the volume must decrease by the same number, if the temperature and pressure remain constant. (The addition of water molecules, or any other molecules, to a gas, without removal of an equal number of other molecules, will necessarily require a change in temperature, pressure, or total volume; that is, a change in "at least" one of these three parameters. If temperature and pressure remain constant, the volume increases, and the dry air molecules that were displaced will initially move out into the additional volume, after which the mixture will eventually become uniform through diffusion.) Hence the mass per unit volume of the gas—its density—decreases. Isaac Newton discovered this phenomenon and wrote about it in his book "Opticks".


title: Humidity

text: The relative humidity of an air–water system is dependent not only on the temperature but also on the absolute pressure of the system of interest. This dependence is demonstrated by considering the air–water system shown below. The system is closed (i.e., no matter enters or leaves the system).


title: Humidity

text: If the system at State A is isobarically heated (heating with no change in system pressure), then the relative humidity of the system decreases because the equilibrium vapor pressure of water increases with increasing temperature. This is shown in State B.


title: Humidity

text: If the system at State A is isothermally compressed (compressed with no change in system temperature), then the relative humidity of the system increases because the partial pressure of water in the system increases with the volume reduction. This is shown in State C. Above 202.64 kPa, the RH would exceed 100% and water may begin to condense.


title: Humidity

text: If the pressure of State A was changed by simply adding more dry air, without changing the volume, the relative humidity would not change.


title: Humidity

text: Therefore, a change in relative humidity can be explained by a change in system temperature, a change in the volume of the system, or change in both of these system properties.


title: Humidity

text: The enhancement factor formula_13 is defined as the ratio of the saturated vapor pressure of water in moist air formula_14 to the saturated vapor pressure of pure water:


title: Humidity

text: The enhancement factor is equal to unity for ideal gas systems. However, in real systems the interaction effects between gas molecules result in a small increase of the equilibrium vapor pressure of water in air relative to equilibrium vapor pressure of pure water vapor. Therefore, the enhancement factor is normally slightly greater than unity for real systems.


title: Humidity

text: The enhancement factor is commonly used to correct the equilibrium vapor pressure of water vapor when empirical relationships, such as those developed by Wexler, Goff, and Gratch, are used to estimate the properties of psychrometric systems.


title: Humidity

text: Buck has reported that, at sea level, the vapor pressure of water in saturated moist air amounts to an increase of approximately 0.5% over the equilibrium vapor pressure of pure water.


title: Humidity

text: Climate control refers to the control of temperature and relative humidity in buildings, vehicles and other enclosed spaces for the purpose of providing for human comfort, health and safety, and of meeting environmental requirements of machines, sensitive materials (for example, historic) and technical processes.


title: Humidity

text: While humidity itself is a climate variable, it also affects other climate variables. Environmental humidity is affected by winds and by rainfall.


title: Humidity

text: The most humid cities on Earth are generally located closer to the equator, near coastal regions. Cities in parts of Asia and Oceania are among the most humid. Bangkok, Ho Chi Minh City, Kuala Lumpur, Hong Kong, Manila, Jakarta, Naha, Singapore, Kaohsiung and Taipei have very high humidity most or all year round because of their proximity to water bodies and the equator and often overcast weather. Some places experience extreme humidity during their rainy seasons combined with warmth giving the feel of a lukewarm sauna, such as Kolkata, Chennai and Kochi in India, and Lahore in Pakistan. Sukkur city located on the Indus River in Pakistan has some of the highest and most uncomfortable dew points in the country, frequently exceeding in the monsoon season.


title: Humidity

text: High temperatures combine with the high dew point to create heat index in excess of . Darwin experiences an extremely humid wet season from December to April. Houston, Miami, San Diego, Osaka, Shanghai, Shenzhen and Tokyo also have an extreme humid period in their summer months. During the South-west and North-east Monsoon seasons (respectively, late May to September and November to March), expect heavy rains and a relatively high humidity post-rainfall. Outside the monsoon seasons, humidity is high (in comparison to countries further from the Equator), but completely sunny days abound. In cooler places such as Northern Tasmania, Australia, high humidity is experienced all year due to the ocean between mainland Australia and Tasmania. In the summer the hot dry air is absorbed by this ocean and the temperature rarely climbs above .


title: Humidity

text: Humidity affects the energy budget and thereby influences temperatures in two major ways. First, water vapor in the atmosphere contains "latent" energy. During transpiration or evaporation, this latent heat is removed from surface liquid, cooling the earth's surface. This is the biggest non-radiative cooling effect at the surface. It compensates for roughly 70% of the average net radiative warming at the surface.


title: Humidity

text: Second, water vapor is the most abundant of all greenhouse gases. Water vapor, like a green lens that allows green light to pass through it but absorbs red light, is a "selective absorber". Like the other greenhouse gasses, water vapor is transparent to most solar energy. However, it absorbs the infrared energy emitted (radiated) upward by the earth's surface, which is the reason that humid areas experience very little nocturnal cooling but dry desert regions cool considerably at night. This selective absorption causes the greenhouse effect. It raises the surface temperature substantially above its theoretical radiative equilibrium temperature with the sun, and water vapor is the cause of more of this warming than any other greenhouse gas.


title: Humidity

text: Unlike most other greenhouse gases, however, water is not merely below its boiling point in all regions of the Earth, but below its freezing point at many altitudes. As a condensible greenhouse gas, it precipitates, with a much lower scale height and shorter atmospheric lifetime — weeks instead of decades. Without other greenhouse gases, Earth's blackbody temperature, below the freezing point of water, would cause water vapor to be removed from the atmosphere. Water vapor is thus a "slave" to the non-condensible greenhouse gases.


title: Humidity

text: Humidity is one of the fundamental abiotic factors that defines any habitat (the tundra, wetlands, and the desert are a few examples), and is a determinant of which animals and plants can thrive in a given environment.


title: Humidity

text: The human body dissipates heat through perspiration and its evaporation. Heat convection, to the surrounding air, and thermal radiation are the primary modes of heat transport from the body. Under conditions of high humidity, the rate of evaporation of sweat from the skin decreases. Also, if the atmosphere is as warm or warmer than the skin during times of high humidity, blood brought to the body surface cannot dissipate heat by conduction to the air. With so much blood going to the external surface of the body, less goes to the active muscles, the brain, and other internal organs. Physical strength declines, and fatigue occurs sooner than it would otherwise. Alertness and mental capacity also may be affected, resulting in "heat stroke" or hyperthermia.


title: Humidity

text: Although humidity is an important factor for thermal comfort, humans are more sensitive to variations in temperature than they are to changes in relative humidity. Humidity has a small effect on thermal comfort outdoors when air temperatures are low, a slightly more pronounced effect at moderate air temperatures, and a much stronger influence at higher air temperatures.


title: Humidity

text: Humans are sensitive to humid air because the human body uses evaporative cooling as the primary mechanism to regulate temperature. Under humid conditions, the "rate" at which perspiration evaporates on the skin is lower than it would be under arid conditions. Because humans perceive the rate of heat transfer from the body rather than temperature itself, we feel warmer when the relative humidity is high than when it is low.


title: Humidity

text: Humans can be comfortable within a wide range of humidities depending on the temperature—from 30 to 70%—but ideally not above the Absolute (60°F Dew Point), between 40% and 60%. In general, higher temperatures will require lower humidities to achieve thermal comfort compared to lower temperatures, with all other factors held constant. For example, with clothing level = 1, metabolic rate = 1.1, and air speed 0.1 m/s, a change in air temperature and mean radiant temperature from 20 °C to 24 °C would lower the maximum acceptable relative humidity from 100% to 65% to maintain thermal comfort conditions. The CBE Thermal Comfort Tool can be used to demonstrate the effect of relative humidity for specific thermal comfort conditions and it can be used to demonstrate compliance with ASHRAE Standard 55-2017.


title: Humidity

text: Some people experience difficulty breathing in humid environments. Some cases may possibly be related to respiratory conditions such as asthma, while others may be the product of anxiety. Sufferers will often hyperventilate in response, causing sensations of numbness, faintness, and loss of concentration, among others.


title: Humidity

text: Very low humidity can create discomfort, respiratory problems, and aggravate allergies in some individuals. Low humidity causes tissue lining nasal passages to dry, crack and become more susceptible to penetration of rhinovirus cold viruses. Extremely low (below 20%) relative humidities may also cause eye irritation. The use of a humidifier in homes, especially bedrooms, can help with these symptoms. Indoor relative humidities should be kept above 30% to reduce the likelihood of the occupant's nasal passages drying out, especially in winter.


title: Humidity

text: Air conditioning reduces discomfort by reducing not just temperature but humidity as well. Heating cold outdoor air can decrease relative humidity levels indoors to below 30%. According to ASHRAE Standard 55-2017: Thermal Environmental Conditions for Human Occupancy, indoor thermal comfort can be achieved through the PMV method with relative humidities ranging from 0% to 100%, depending on the levels of the other factors contributing to thermal comfort. However, the recommended range of indoor relative humidity in air conditioned buildings is generally 30–60%.


title: Humidity

text: Higher humidity reduces the infectivity of aerosolized influenza virus. A study concluded, "Maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus."


title: Humidity

text: Mucociliary clearance in the respiratory tract is also hindered by low humidity. One study in dogs found that mucus transport was lower at an absolute humidity of 9 g water/m than at 30 g water/m.


title: Humidity

text: Increased humidity can also lead to changes in total body water that usually leads to moderate weight gain, especially if one is acclimated to working or exercising in hot and humid weather.


title: Humidity

text: Common construction methods often produce building enclosures with a poor thermal boundary, requiring an insulation and air barrier system designed to retain indoor environmental conditions while resisting external environmental conditions. The energy-efficient, heavily sealed architecture introduced in the 20th century also sealed off the movement of moisture, and this has resulted in a secondary problem of condensation forming in and around walls, which encourages the development of mold and mildew. Additionally, buildings with foundations not properly sealed will allow water to flow through the walls due to capillary action of pores found in masonry products. Solutions for energy-efficient buildings that avoid condensation are a current topic of architecture.


title: Humidity

text: For climate control in buildings using HVAC systems, the key is to maintain the relative humidity at a comfortable range—low enough to be comfortable but high enough to avoid problems associated with very dry air.


title: Humidity

text: When the temperature is high and the relative humidity is low, evaporation of water is rapid; soil dries, wet clothes hung on a line or rack dry quickly, and perspiration readily evaporates from the skin. Wooden furniture can shrink, causing the paint that covers these surfaces to fracture.


title: Humidity

text: When the temperature is low and the relative humidity is high, evaporation of water is slow. When relative humidity approaches 100%, condensation can occur on surfaces, leading to problems with mold, corrosion, decay, and other moisture-related deterioration. Condensation can pose a safety risk as it can promote the growth of mold and wood rot as well as possibly freezing emergency exits shut.


title: Humidity

text: Certain production and technical processes and treatments in factories, laboratories, hospitals, and other facilities require specific relative humidity levels to be maintained using humidifiers, dehumidifiers and associated control systems.


title: Humidity

text: The basic principles for buildings, above, also apply to vehicles. In addition, there may be safety considerations. For instance, high humidity inside a vehicle can lead to problems of condensation, such as misting of windshields and shorting of electrical components. In vehicles and pressure vessels such as pressurized airliners, submersibles and spacecraft, these considerations may be critical to safety, and complex environmental control systems including equipment to maintain pressure are needed.


title: Humidity

text: Airliners operate with low internal relative humidity, often under 20%, especially on long flights. The low humidity is a consequence of drawing in the very cold air with a low absolute humidity, which is found at airliner cruising altitudes. Subsequent warming of this air lowers its relative humidity. This causes discomfort such as sore eyes, dry skin, and drying out of mucosa, but humidifiers are not employed to raise it to comfortable mid-range levels because the volume of water required to be carried on board can be a significant weight penalty. As airliners descend from colder altitudes into warmer air (perhaps even flying through clouds a few thousand feet above the ground), the ambient relative humidity can increase dramatically. Some of this moist air is usually drawn into the pressurized aircraft cabin and into other non-pressurized areas of the aircraft and condenses on the cold aircraft skin. Liquid water can usually be seen running along the aircraft skin, both on the inside and outside of the cabin. Because of the drastic changes in relative humidity inside the vehicle, components must be qualified to operate in those environments. The recommended environmental qualifications for most commercial aircraft components is listed in RTCA DO-160.


title: Humidity

text: Cold, humid air can promote the formation of ice, which is a danger to aircraft as it affects the wing profile and increases weight. Naturally aspirated internal combustion engines have a further danger of ice forming inside the carburetor. Aviation weather reports (METARs) therefore include an indication of relative humidity, usually in the form of the dew point.


title: Humidity

text: Pilots must take humidity into account when calculating takeoff distances, because high humidity requires longer runways and will decrease climb performance.


title: Humidity

text: Density altitude is the altitude relative to the standard atmosphere conditions (International Standard Atmosphere) at which the air density would be equal to the indicated air density at the place of observation, or, in other words, the height when measured in terms of the density of the air rather than the distance from the ground. "Density Altitude" is the pressure altitude adjusted for non-standard temperature.


title: Humidity

text: An increase in temperature, and, to a much lesser degree, humidity, will cause an increase in density altitude. Thus, in hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.


title: Humidity

text: Electronic devices are often rated to operate only under certain humidity conditions (e.g., 10% to 90%). At the top end of the range, moisture may increase the conductivity of permeable insulators leading to malfunction. Too low humidity may make materials brittle. A particular danger to electronic items, regardless of the stated operating humidity range, is condensation. When an electronic item is moved from a cold place (e.g., garage, car, shed, air conditioned space in the tropics) to a warm humid place (house, outside tropics), condensation may coat circuit boards and other insulators, leading to short circuit inside the equipment. Such short circuits may cause substantial permanent damage if the equipment is powered on before the condensation has evaporated. A similar condensation effect can often be observed when a person wearing glasses comes in from the cold (i.e. the glasses become foggy). It is advisable to allow electronic equipment to acclimatise for several hours, after being brought in from the cold, before powering on. Some electronic devices can detect such a change and indicate, when plugged in and usually with a small droplet symbol, that they cannot be used until the risk from condensation has passed. In situations where time is critical, increasing air flow through the device's internals, such as removing the side panel from a PC case and directing a fan to blow into the case, will reduce significantly the time needed to acclimatise to the new environment.


title: Humidity

text: In contrast, a very low humidity level favors the build-up of static electricity, which may result in spontaneous shutdown of computers when discharges occur. Apart from spurious erratic function, electrostatic discharges can cause dielectric breakdown in solid-state devices, resulting in irreversible damage. Data centers often monitor relative humidity levels for these reasons.


title: Humidity

text: High humidity can often have a negative effect on the capacity of chemical plants and refineries that use furnaces as part of a certain processes (e.g., steam reforming, wet sulfuric acid processes). For example, because humidity reduces ambient oxygen concentrations (dry air is typically 20.9% oxygen, but at 100% relative humidity the air is 20.4% oxygen), flue gas fans must intake air at a higher rate than would otherwise be required to maintain the same firing rate.


title: Humidity

text: High humidity in the oven, represented by an elevated wet-bulb temperature, increases the thermal conductivity of the air around the baked item, leading to a quicker baking process or even burning. Conversely, low humidity slows the baking process down.


title: Humidity

text: At 100% relative humidity, air is saturated and at its dew point: the water vapor pressure would permit neither evaporation of nearby liquid water nor condensation to grow the nearby water; neither sublimation of nearby ice nor deposition to grow the nearby ice.


title: Humidity

text: Relative humidity can exceed 100%, in which case the air is supersaturated. Cloud formation requires supersaturated air. Cloud condensation nuclei lower the level of supersaturation required to form fogs and clouds - in the absence of nuclei around which droplets or ice can form, a higher level of supersaturation is required for these droplets or ice crystals to form spontaneously. In the Wilson cloud chamber, which is used in nuclear physics experiments, a state of supersaturation is created within the chamber, and moving subatomic particles act as condensation nuclei so trails of fog show the paths of those particles.


title: Humidity

text: For a given dew point and its corresponding absolute humidity, the relative humidity will change inversely, albeit nonlinearly, with the temperature. This is because the vapor pressure of water increases with temperature—the operative principle behind everything from hair dryers to dehumidifiers.


title: Humidity

text: Due to the increasing potential for a higher water vapor partial pressure at higher air temperatures, the water content of air at sea level can get as high as 3% by mass at compared to no more than about 0.5% by mass at . This explains the low levels (in the absence of measures to add moisture) of humidity in heated structures during winter, resulting in dry skin, itchy eyes, and persistence of static electric charges. Even with saturation (100% relative humidity) outdoors, heating of infiltrated outside air that comes indoors raises its moisture capacity, which lowers relative humidity and increases evaporation rates from moist surfaces indoors (including human bodies and household plants.)


title: Humidity

text: Similarly, during summer in humid climates a great deal of liquid water condenses from air cooled in air conditioners. Warmer air is cooled below its dew point, and the excess water vapor condenses. This phenomenon is the same as that which causes water droplets to form on the outside of a cup containing an ice-cold drink.


title: Humidity

text: A useful rule of thumb is that the maximum absolute humidity doubles for every increase in temperature. Thus, the relative humidity will drop by a factor of 2 for each increase in temperature, assuming conservation of absolute moisture. For example, in the range of normal temperatures, air at and 50% relative humidity will become saturated if cooled to , its dew point, and air at 80% relative humidity warmed to will have a relative humidity of only 29% and feel dry. By comparison, thermal comfort standard ASHRAE 55 requires systems designed to control humidity to maintain a dew point of though no lower humidity limit is established.


title: Humidity

text: Water vapor is a lighter gas than other gaseous components of air at the same temperature, so humid air will tend to rise by natural convection. This is a mechanism behind thunderstorms and other weather phenomena. Relative humidity is often mentioned in weather forecasts and reports, as it is an indicator of the likelihood of dew, or fog. In hot summer weather, it also increases the apparent temperature to humans (and other animals) by hindering the evaporation of perspiration from the skin as the relative humidity rises. This effect is calculated as the heat index or humidex.


title: Humidity

text: A device used to measure humidity is called a hygrometer; one used to regulate it is called a humidistat, or sometimes hygrostat. (These are analogous to a thermometer and thermostat for temperature, respectively.)


title: Aikido

text: Aikido ( , , , ) is a modern Japanese martial art that is split into many different styles, including Iwama Ryu, Iwama Shin Shin Aiki Shuren Kai, Shodokan Aikido, Yoshinkan, Renshinkai, Aikikai and Ki Aikido. Aikido is now practiced in around 140 countries. It was originally developed by Morihei Ueshiba, as a synthesis of his martial studies, philosophy and religious beliefs. Ueshiba's goal was to create an art that practitioners could use to defend themselves while also protecting their attackers from injury. Aikido is often translated as "the way of unifying (with) life energy" or as "the way of harmonious spirit". According to the founder's philosophy, the primary goal in the practice of aikido is to overcome oneself instead of cultivating violence or aggressiveness. Morihei Ueshiba used the phrase to refer to this principle.


title: Aikido

text: Aikido's fundamental principles include: (entering), , (breathing control), (triangular principle) and (turning) movements that redirect the opponent's attack momentum. Its curriculum comprises various techniques, primarily throws and joint locks. It also includes a weapons system encompassing the , and .


title: Aikido

text: Aikido derives mainly from the martial art of Daitō-ryū Aiki-jūjutsu, but began to diverge from it in the late 1920s, partly due to Ueshiba's involvement with the Ōmoto-kyō religion. Ueshiba's early students' documents bear the term .


title: Aikido

text: Ueshiba's senior students have different approaches to aikido, depending partly on when they studied with him. Today, aikido is found all over the world in a number of styles, with broad ranges of interpretation and emphasis. However, they all share techniques formulated by Ueshiba and most have concern for the well-being of the attacker.


title: Aikido

text: The term does not readily appear in the Japanese language outside the scope of budō. This has led to many possible interpretations of the word.


title: Aikido

text: The term in Aikido is found in many other Japanese martial arts such as, judo and kendo, and in various non-martial arts, such as Japanese calligraphy (), flower arranging () and tea ceremony ( or ).


title: Aikido

text: Therefore, from a purely literal interpretation, aikido is the "Way of combining forces" or "Way of unifying energy", in which the term refers to the martial arts principle or tactic of blending with an attacker's movements for the purpose of controlling their actions with minimal effort. One applies by understanding the rhythm and intent of the attacker to find the optimal position and timing to apply a counter-technique.


title: Aikido

text: Aikido was created by (1883–1969), referred to by some aikido practitioners as ("Great Teacher"). The term "aikido" was coined in the 20th century. Ueshiba envisioned aikido not only as the synthesis of his martial training, but as an expression of his personal philosophy of universal peace and reconciliation. During Ueshiba's lifetime and continuing today, aikido has evolved from the that Ueshiba studied into a variety of expressions by martial artists throughout the world.


title: Aikido

text: Ueshiba developed aikido primarily during the late 1920s through the 1930s through the synthesis of the older martial arts that he had studied. The core martial art from which aikido derives is Daitō-ryū Aiki-jūjutsu, which Ueshiba studied directly with Takeda Sōkaku, the reviver of that art. Additionally, Ueshiba is known to have studied Tenjin Shin'yō-ryū with Tozawa Tokusaburō in Tokyo in 1901, Gotōha Yagyū Shingan-ryū under Nakai Masakatsu in Sakai from 1903 to 1908, and judo with (1894–1972) in Tanabe in 1911.


title: Aikido

text: The art of is the primary technical influence on aikido. Along with empty-handed throwing and joint-locking techniques, Ueshiba incorporated training movements with weapons, such as those for the spear (), short staff (), and possibly the . Aikido also derives much of its technical structure from the art of swordsmanship ().


title: Aikido

text: Ueshiba moved to Hokkaidō in 1912, and began studying under Takeda Sokaku in 1915; His official association with Daitō-ryū continued until 1937. However, during the latter part of that period, Ueshiba had already begun to distance himself from Takeda and the . At that time Ueshiba referred to his martial art as "Aiki Budō". It is unclear exactly when Ueshiba began using the name "aikido", but it became the official name of the art in 1942 when the Greater Japan Martial Virtue Society () was engaged in a government sponsored reorganization and centralization of Japanese martial arts.


title: Aikido

text: After Ueshiba left Hokkaidō in 1919, he met and was profoundly influenced by Onisaburo Deguchi, the spiritual leader of the Ōmoto-kyō religion (a neo-Shinto movement) in Ayabe. One of the primary features of Ōmoto-kyō is its emphasis on the attainment of utopia during one's life. This idea was a great influence on Ueshiba's martial arts philosophy of extending love and compassion especially to those who seek to harm others. Aikido demonstrates this philosophy in its emphasis on mastering martial arts so that one may receive an attack and harmlessly redirect it. In an ideal resolution, not only is the receiver unharmed, but so is the attacker.


title: Aikido

text: In addition to the effect on his spiritual growth, the connection with Deguchi gave Ueshiba entry to elite political and military circles as a martial artist. As a result of this exposure, he was able to attract not only financial backing but also gifted students. Several of these students would found their own styles of aikido.


title: Aikido

text: Aikido was first introduced to the rest of the world in 1951 by Minoru Mochizuki with a visit to France, where he demonstrated aikido techniques to judo students. He was followed by Tadashi Abe in 1952, who came as the official Aikikai Hombu representative, remaining in France for seven years. Kenji Tomiki toured with a delegation of various martial arts through 15 continental states of the United States in 1953. Later that year, Koichi Tohei was sent by Aikikai Hombu to Hawaii for a full year, where he set up several dōjō. This trip was followed by several subsequent visits and is considered the formal introduction of aikido to the United States. The United Kingdom followed in 1955; Italy in 1964 by Hiroshi Tada; and Germany in 1965 by Katsuaki Asai. Designated the "Official Delegate for Europe and Africa" by Morihei Ueshiba, Masamichi Noro arrived in France in September 1961. Seiichi Sugano was appointed to introduce aikido to Australia in 1965. Today there are aikido dōjō throughout the world.


title: Aikido

text: The largest aikido organization is the Aikikai Foundation, which remains under the control of the Ueshiba family. However, aikido has developed into many styles, most of which were formed by Morihei Ueshiba's major students.


title: Aikido

text: The earliest independent styles to emerge were Yoseikan Aikido, begun by Minoru Mochizuki in 1931, Yoshinkan Aikido, founded by Gozo Shioda in 1955, and Shodokan Aikido, founded by Kenji Tomiki in 1967. The emergence of these styles pre-dated Ueshiba's death and did not cause any major upheavals when they were formalized. Shodokan Aikido, however, was controversial, since it introduced a unique rule-based competition that some felt was contrary to the spirit of aikido.


title: Aikido

text: After Ueshiba's death in 1969, two more major styles emerged. Significant controversy arose with the departure of the Aikikai Hombu Dojo's chief instructor Koichi Tohei, in 1974. Tohei left as a result of a disagreement with the son of the founder, Kisshomaru Ueshiba, who at that time headed the Aikikai Foundation. The disagreement was over the proper role of development in regular aikido training. After Tohei left, he formed his own style, called Shin Shin Toitsu Aikido, and the organization that governs it, the Ki Society ().


title: Aikido

text: A final major style evolved from Ueshiba's retirement in Iwama, Ibaraki and the teaching methodology of long term student Morihiro Saito. It is unofficially referred to as the "Iwama style", and at one point a number of its followers formed a loose network of schools they called Iwama Ryu. Although Iwama style practitioners remained part of the Aikikai until Saito's death in 2002, followers of Saito subsequently split into two groups. One remained with the Aikikai and the other formed the independent Shinshin Aikishuren Kai in 2004 around Saito's son Hitohiro Saito.


title: Aikido

text: Today, the major styles of aikido are each run by a separate governing organization, have their own in Japan, and are taught throughout the world.


title: Aikido

text: The study of is an important component of aikido. The term does not specifically refer to either physical or mental training, as it encompasses both. The kanji for was written in its older form as up until the Japanese governmental writing reforms after World War II, and now is more prevalently seen in its modern form of . This form has the removal of the eight directions denoting the pre and post natal energies of (Chinese – ) also known in the Art of Aikido as "Source energy".


title: Aikido

text: The character for is used in everyday Japanese terms, such as , or . has many meanings, including "ambience", "mind", "mood", or "intention and action", however, in traditional martial arts and medicine it is often referred to in its more general terminology as "life energy". Gozo Shioda's Yoshinkan Aikido, considered one of the "hard styles", largely follows Ueshiba's teachings from before World War II, and surmises that the secret to lies in timing and the application of the whole body's strength to a single point. In later years, Ueshiba's application of in aikido took on a softer, more gentle feel. This concept was known as Takemusu Aiki, and many of his later students teach about from this perspective. Koichi Tohei's Ki Society centers almost exclusively around the study of the empirical (albeit subjective) experience of , with students' proficiency in aikido techniques and development ranked separately.


title: Aikido

text: In aikido, as in virtually all Japanese martial arts, there are both physical and mental aspects of training. The physical training in aikido is diverse, covering both general physical fitness and conditioning, as well as specific techniques. Because a substantial portion of any aikido curriculum consists of throws, beginners learn how to safely fall or roll. The specific techniques for attack include both strikes and grabs; the techniques for defense consist of throws and pins. After basic techniques are learned, students study freestyle defense against multiple opponents, and techniques with weapons.


title: Aikido

text: Physical training goals pursued in conjunction with aikido include controlled relaxation, correct movement of joints such as hips and shoulders, flexibility, and endurance, with less emphasis on strength training. In aikido, pushing or extending movements are much more common than pulling or contracting movements. This distinction can be applied to general fitness goals for the aikido practitioner.


title: Aikido

text: In aikido, specific muscles or muscle groups are not isolated and worked to improve tone, mass, or power. Aikido-related training emphasizes the use of coordinated whole-body movement and balance similar to yoga or pilates. For example, many dōjōs begin each class with , which may include stretching and (break falls).


title: Aikido

text: Aikido training is based primarily on two partners practicing pre-arranged forms () rather than freestyle practice. The basic pattern is for the receiver of the technique () to initiate an attack against the person who applies the technique—the , or (depending on aikido style), also referred to as (when applying a throwing technique), who neutralises this attack with an aikido technique.


title: Aikido

text: Both halves of the technique, that of and that of , are considered essential to aikido training. Both are studying aikido principles of blending and adaptation. learns to blend with and control attacking energy, while learns to become calm and flexible in the disadvantageous, off-balance positions in which places them. This "receiving" of the technique is called . continuously seeks to regain balance and cover vulnerabilities (e.g., an exposed side), while uses position and timing to keep off-balance and vulnerable. In more advanced training, will sometimes apply to regain balance and pin or throw .


title: Aikido

text: Aikido techniques are usually a defense against an attack, so students must learn to deliver various types of attacks to be able to practice aikido with a partner. Although attacks are not studied as thoroughly as in striking-based arts, attacks with intent (such as a strong strike or an immobilizing grab) are needed to study correct and effective application of technique.


title: Aikido

text: Many of the of aikido resemble cuts from a sword or other grasped object, which indicate its origins in techniques intended for armed combat. Other techniques, which explicitly appear to be punches (), are practiced as thrusts with a knife or sword. Kicks are generally reserved for upper-level variations; reasons cited include that falls from kicks are especially dangerous, and that kicks (high kicks in particular) were uncommon during the types of combat prevalent in feudal Japan.


title: Aikido

text: Beginners in particular often practice techniques from grabs, both because they are safer and because it is easier to feel the energy and the direction of the movement of force of a hold than it is for a strike. Some grabs are historically derived from being held while trying to draw a weapon, whereupon a technique could then be used to free oneself and immobilize or strike the attacker while they are grabbing the defender. The following are examples of some basic grabs:


title: Aikido

text: The following are a sample of the basic or widely practiced throws and pins. Many of these techniques derive from Daitō-ryū Aiki-jūjutsu, but some others were invented by Morihei Ueshiba. The precise terminology for some may vary between organisations and styles; the following are the terms used by the Aikikai Foundation. Note that despite the names of the first five techniques listed, they are not universally taught in numeric order.


title: Aikido

text: Aikido makes use of body movement () to blend the movement of with the movement of . For example, an "entering" () technique consists of movements inward towards , while a technique uses a pivoting motion.


title: Aikido

text: Additionally, an technique takes place in front of , whereas an technique takes place to their side; a technique is applied with motion to the front of , and a version is applied with motion towards the rear of , usually by incorporating a turning or pivoting motion. Finally, most techniques can be performed while in a seated posture (). Techniques where both and are standing are called , techniques where both start off in are called , and techniques performed with standing and sitting are called ().


title: Aikido

text: From these few basic techniques, there are numerous of possible implementations. For example, can be applied to an opponent moving forward with a strike (perhaps with an type of movement to redirect the incoming force), or to an opponent who has already struck and is now moving back to reestablish distance (perhaps an version). Specific aikido are typically referred to with the formula "attack-technique(-modifier)"; , for example, refers to any technique executed when is holding one wrist. This could be further specified as (referring to any forward-moving technique from that grab).


title: Aikido

text: Weapons training in aikido traditionally includes the short staff () (these techniques closely resemble the use of the bayonet, or Jūkendō), the wooden sword (), and the knife (). Some schools incorporate firearm-disarming techniques, where either weapon-taking and/or weapon-retention may be taught. Some schools, such as the Iwama style of Morihiro Saito, usually spend substantial time practicing with both and , under the names of , and , respectively.


title: Aikido

text: The founder developed many of the empty-handed techniques from traditional sword, spear and bayonet movements. Consequently, the practice of the weapons arts gives insight into the origin of techniques and movements, and reinforces the concepts of distance, timing, foot movement, presence and connectedness with one's training partner(s).


title: Aikido

text: One feature of aikido is training to defend against multiple attackers, often called , or . Freestyle practice with multiple attackers called is a key part of most curricula and is required for the higher-level ranks. exercises a person's ability to intuitively perform techniques in an unstructured environment. Strategic choice of techniques, based on how they reposition the student relative to other attackers, is important in training. For instance, an technique might be used to neutralise the current attacker while turning to face attackers approaching from behind.


title: Aikido

text: In Shodokan Aikido, differs in that it is not performed with multiple persons with defined roles of defender and attacker, but between two people, where both participants attack, defend, and counter at will. In this respect it resembles judo .


title: Aikido

text: In applying a technique during training, it is the responsibility of to prevent injury to by employing a speed and force of application that is appropriate with their partner's proficiency in . When injuries (especially to the joints) occur, they are often the result of a misjudging the ability of to receive the throw or pin.


title: Aikido

text: A study of injuries in the martial arts showed that the type of injuries varied considerably from one art to the other. Soft tissue injuries are one of the most common types of injuries found within aikido, as well as joint strain and stubbed fingers and toes. Several deaths from head-and-neck injuries, caused by aggressive in a hazing context, have been reported.


title: Aikido

text: Aikido training is mental as well as physical, emphasizing the ability to relax the mind and body even under the stress of dangerous situations. This is necessary to enable the practitioner to perform the 'enter-and-blend' movements that underlie aikido techniques, wherein an attack is met with confidence and directness. Morihei Ueshiba once remarked that one "must be willing to receive 99% of an opponent's attack and stare death in the face" in order to execute techniques without hesitation. As a martial art concerned not only with fighting proficiency but with the betterment of daily life, this mental aspect is of key importance to aikido practitioners.


title: Aikido

text: Aikido practitioners (commonly called outside Japan) generally progress by promotion through a series of "grades" (), followed by a series of "degrees" (), pursuant to formal testing procedures. Some aikido organizations use belts to distinguish practitioners' grades, often simply white and black belts to distinguish and grades, although some use various belt colors. Testing requirements vary, so a particular rank in one organization is not comparable or interchangeable with the rank of another. Some dōjōs have an age requirement before students can take the rank exam.


title: Aikido

text: The uniform worn for practicing aikido () is similar to the training uniform () used in most other modern martial arts; simple trousers and a wraparound jacket, usually white. Both thick ("judo-style"), and thin ("karate-style") cotton tops are used. Aikido-specific tops are available with shorter sleeves which reach to just below the elbow.


title: Aikido

text: Most aikido systems add a pair of wide pleated black or indigo trousers known as (used also in Naginatajutsu, kendo, and iaido). In many schools, the wearing of is reserved for practitioners with ranks or for instructors, while others allow all practitioners to wear a regardless of rank.


title: Aikido

text: Aikido styles vary in their intention as due to its holistic nature. The most common differences noted in aikido, when observed externally, relate to the intensity and realism of training. Stanley Pranin has observed that some criticism may stem from weak attacks from , allowing for a conditioned response from , resulting in underdevelopment of the skills needed for the safe and effective practice of both partners.


title: Aikido

text: To counteract this, some styles allow students to become less compliant over time, but, in keeping with the core philosophies, this is after having demonstrated proficiency in being able to protect themselves and their training partners. Shodokan Aikido addresses the issue by practicing in a competitive format. Such adaptations are debated between styles, with some maintaining that there is no need to adjust their methods because either the criticisms are unjustified, or that they are not training for self-defense or combat effectiveness, but spiritual, fitness or other reasons.


title: Aikido

text: Reasons for the difference and diversity of teachings, intention, and forms of aikido can be traced to the shift in training focus after the end of Ueshiba's seclusion in Iwama from 1942 to the mid-1950s, as he increasingly emphasized the spiritual and philosophical aspects of aikido. As a result, strikes to vital points by , entering () and initiation of techniques by , the distinction between (front side) and (back side) techniques, and the use of weapons, were all de-emphasized or eliminated from practice.


title: Aikido

text: Conversely, some styles of aikido place less importance on the spiritual practices emphasized by Ueshiba. According to Minoru Shibata of "Aikido Journal":


title: Aikido

text: O-Sensei's aikido was not a continuation and extension of the old and has a distinct discontinuity with past martial and philosophical concepts.


title: Aikido

text: In other words, aikido practitioners who focus on aikido's roots in traditional or are said to be diverging from what Ueshiba taught, as some critics urge practitioners:


title: Aikido

text: [Ueshiba's] transcendence to the spiritual and universal reality were the fundamentals of the paradigm that he demonstrated.


title: Amouranth

text: Kaitlyn Siragusa, better known as Amouranth , is an American social media personality, streamer, and OnlyFans creator. Siragusa is also known for her ASMR Twitch livestreams.


title: Amouranth

text: Siragusa initially was a cosplayer, appearing at character parties for children and hospital visits. In 2016, she was asked by streaming company Twitch to join as a content creator and livestream making costumes. She accepted and by 2021, became the most popular female streamer on Twitch, known her dancing, ASMR and hot tub streaming content.


title: Amouranth

text: By July 2022, Siragusa was reported to have earned $33 million through OnlyFans. On October 8, 2021, Siragusa was banned from Twitch for the fifth time, as well as Instagram and TikTok. In November 2021, Siragusa announced on her Twitter that she had bought a gas station, which she is renting out to a Circle K.


title: Amouranth

text: In January 2022, she announced that she had also bought an inflatable pool toy company. In April 2022, she announced that she was quitting her OnlyFans and associated online activities to focus on Twitch by the end of June of that year. In July 2022, she announced she was starting a company matching personal assistants with content creators.


title: Amouranth

text: On October 15, 2022, Siragusa revealed on-stream that she had been married for several years, after her stream was interrupted by her husband, who could be heard verbally abusing her live on stream. Siragusa alleged that her husband controls her finances, coerced her to stream more than she was willing to, and threatened to kill her dogs if she did not obey his demands. A few days following the incident Siragusa stated she was seeking legal and emotional counsel, regained access to her finances and that her husband was out of her life and is seeking unspecified "help".


title: Cholesterol

text: Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membranes. When chemically isolated, it is a yellowish crystalline solid.


title: Cholesterol

text: Cholesterol also serves as a precursor for the biosynthesis of steroid hormones, bile acid and vitamin D. Cholesterol is the principal sterol synthesized by all animals. In vertebrates, hepatic cells typically produce the greatest amounts. It is absent among prokaryotes (bacteria and archaea), although there are some exceptions, such as "Mycoplasma", which require cholesterol for growth.


title: Cholesterol

text: François Poulletier de la Salle first identified cholesterol in solid form in gallstones in 1769. However, it was not until 1815 that chemist Michel Eugène Chevreul named the compound "cholesterine".


title: Cholesterol

text: The word "cholesterol" comes from the Ancient Greek "chole-" (bile) and "stereos" (solid), followed by the chemical suffix "-ol" for an alcohol.


title: Cholesterol

text: Cholesterol is essential for all animal life, with each cell capable of synthesizing it by way of a complex 37-step process. This begins with the mevalonate or HMG-CoA reductase pathway, the target of statin drugs, which encompasses the first 18 steps. This is followed by 19 additional steps to convert the resulting lanosterol into cholesterol.


title: Cholesterol

text: A human male weighing 68 kg (150 lb) normally synthesizes about 1 gram (1,000 mg) of cholesterol per day, and his body contains about 35 g, mostly contained within the cell membranes. Typical daily cholesterol dietary intake for a man in the United States is 307 mg.


title: Cholesterol

text: Most ingested cholesterol is esterified, which causes it to be poorly absorbed by the gut. The body also compensates for absorption of ingested cholesterol by reducing its own cholesterol synthesis. For these reasons, cholesterol in food, seven to ten hours after ingestion, has little, if any effect on concentrations of cholesterol in the blood. However, during the first seven hours after ingestion of cholesterol, as absorbed fats are being distributed around the body within extracellular water by the various lipoproteins (which transport all fats in the water outside cells), the concentrations increase.


title: Cholesterol

text: Plants make cholesterol in very small amounts. In larger quantities they produce phytosterols, chemically similar substances which can compete with cholesterol for reabsorption in the intestinal tract, thus potentially reducing cholesterol reabsorption. When intestinal lining cells absorb phytosterols, in place of cholesterol, they usually excrete the phytosterol molecules back into the GI tract, an important protective mechanism. The intake of naturally occurring phytosterols, which encompass plant sterols and stanols, ranges between ≈200–300 mg/day depending on eating habits. Specially designed vegetarian experimental diets have been produced yielding upwards of 700 mg/day.


title: Cholesterol

text: Cholesterol composes about 30% of all animal cell membranes. It is required to build and maintain membranes and modulates membrane fluidity over the range of physiological temperatures. The hydroxyl group of each cholesterol molecule interacts with water molecules surrounding the membrane, as do the polar heads of the membrane phospholipids and sphingolipids, while the bulky steroid and the hydrocarbon chain are embedded in the membrane, alongside the nonpolar fatty-acid chain of the other lipids. Through the interaction with the phospholipid fatty-acid chains, cholesterol increases membrane packing, which both alters membrane fluidity and maintains membrane integrity so that animal cells do not need to build cell walls (like plants and most bacteria). The membrane remains stable and durable without being rigid, allowing animal cells to change shape and animals to move.


title: Cholesterol

text: The structure of the tetracyclic ring of cholesterol contributes to the fluidity of the cell membrane, as the molecule is in a "trans" conformation making all but the side chain of cholesterol rigid and planar. In this structural role, cholesterol also reduces the permeability of the plasma membrane to neutral solutes, hydrogen ions, and sodium ions.


title: Cholesterol

text: Cholesterol regulates the biological process of substrate presentation and the enzymes that use substrate presentation as a mechanism of their activation. (PLD2) is a well-defined example of an enzyme activated by substrate presentation. The enzyme is palmitoylated causing the enzyme to traffic to cholesterol dependent lipid domains sometimes called "lipid rafts". The substrate of phospholipase D is phosphatidylcholine (PC) which is unsaturated and is of low abundance in lipid rafts. PC localizes to the disordered region of the cell along with the polyunsaturated lipid phosphatidylinositol 4,5-bisphosphate (PIP2). PLD2 has a PIP2 binding domain. When PIP2 concentration in the membrane increases, PLD2 leaves the cholesterol-dependent domains and binds to PIP2 where it then gains access to its substrate PC and commences catalysis based on substrate presentation.


title: Cholesterol

text: Cholesterol is also implicated in cell signaling processes, assisting in the formation of lipid rafts in the plasma membrane, which brings receptor proteins in close proximity with high concentrations of second messenger molecules. In multiple layers, cholesterol and phospholipids, both electrical insulators, can facilitate speed of transmission of electrical impulses along nerve tissue. For many neuron fibers, a myelin sheath, rich in cholesterol since it is derived from compacted layers of Schwann cell membrane, provides insulation for more efficient conduction of impulses. Demyelination (loss of some of these Schwann cells) is believed to be part of the basis for multiple sclerosis.


title: Cholesterol

text: Cholesterol binds to and affects the gating of a number of ion channels such as the nicotinic acetylcholine receptor, GABA receptor, and the inward-rectifier potassium channel. Cholesterol also activates the estrogen-related receptor alpha (ERRα), and may be the endogenous ligand for the receptor. The constitutively active nature of the receptor may be explained by the fact that cholesterol is ubiquitous in the body. Inhibition of ERRα signaling by reduction of cholesterol production has been identified as a key mediator of the effects of statins and bisphosphonates on bone, muscle, and macrophages. On the basis of these findings, it has been suggested that the ERRα should be de-orphanized and classified as a receptor for cholesterol.


title: Cholesterol

text: Within cells, cholesterol is also a precursor molecule for several biochemical pathways. For example, it is the precursor molecule for the synthesis of vitamin D in the calcium metabolism and all steroid hormones, including the adrenal gland hormones cortisol and aldosterone, as well as the sex hormones progesterone, estrogens, and testosterone, and their derivatives.


title: Cholesterol

text: The stratum corneum is the outermost layer of the epidermis. It is composed of terminally differentiated and enucleated corneocytes that reside within a lipid matrix, like "bricks and mortar." Together with ceramides and free fatty acids, cholesterol forms the lipid mortar, a water-impermeable barrier that prevents evaporative water loss. As a general rule of thumb, the epidermal lipid matrix is composed of an equimolar mixture of ceramides (~50% by weight), cholesterol (~ 25% by weight), and free fatty acids (~15% by weight), with smaller quantities of other lipids also being present. Cholesterol sulfate reaches its highest concentration in the granular layer of the epidermis. Steroid sulfate sulfatase then decreases its concentration in the stratum corneum, the outermost layer of the epidermis. The relative abundance of cholesterol sulfate in the epidermis varies across different body sites with the heel of the foot having the lowest concentration.


title: Cholesterol

text: Cholesterol is recycled in the body. The liver excretes cholesterol into biliary fluids, which are then stored in the gallbladder, which then excretes them in a non-esterified form (via bile) into the digestive tract. Typically, about 50% of the excreted cholesterol is reabsorbed by the small intestine back into the bloodstream.


title: Cholesterol

text: All animal cells (exceptions exist within the invertebrates) manufacture cholesterol, for both membrane structure and other uses, with relative production rates varying by cell type and organ function. About 80% of total daily cholesterol production occurs in the liver and the intestines; other sites of higher synthesis rates include the brain, the adrenal glands, and the reproductive organs.


title: Cholesterol

text: Synthesis within the body starts with the mevalonate pathway where two molecules of acetyl CoA condense to form acetoacetyl-CoA. This is followed by a second condensation between acetyl CoA and acetoacetyl-CoA to form 3-hydroxy-3-methylglutaryl CoA (HMG-CoA).


title: Cholesterol

text: This molecule is then reduced to mevalonate by the enzyme HMG-CoA reductase. Production of mevalonate is the rate-limiting and irreversible step in cholesterol synthesis and is the site of action for statins (a class of cholesterol-lowering drugs).


title: Cholesterol

text: Mevalonate is finally converted to isopentenyl pyrophosphate (IPP) through two phosphorylation steps and one decarboxylation step that requires ATP.


title: Cholesterol

text: Three molecules of isopentenyl pyrophosphate condense to form farnesyl pyrophosphate through the action of geranyl transferase.


title: Cholesterol

text: Two molecules of farnesyl pyrophosphate then condense to form squalene by the action of squalene synthase in the endoplasmic reticulum.


title: Cholesterol

text: Finally, lanosterol is converted to cholesterol via either of two pathways, the Bloch pathway, or the Kandutsch-Russell pathway.


title: Cholesterol

text: The final 19 steps to cholesterol contain NADPH and oxygen to help oxidize methyl groups for removal of carbons, mutases to move alkene groups, and NADH to help reduce ketones.


title: Cholesterol

text: Konrad Bloch and Feodor Lynen shared the Nobel Prize in Physiology or Medicine in 1964 for their discoveries concerning some of the mechanisms and methods of regulation of cholesterol and fatty acid metabolism.


title: Cholesterol

text: Biosynthesis of cholesterol is directly regulated by the cholesterol levels present, though the homeostatic mechanisms involved are only partly understood. A higher intake of food leads to a net decrease in endogenous production, whereas a lower intake of food has the opposite effect. The main regulatory mechanism is the sensing of intracellular cholesterol in the endoplasmic reticulum by the protein SREBP (sterol regulatory element-binding protein 1 and 2). In the presence of cholesterol, SREBP is bound to two other proteins: SCAP (SREBP cleavage-activating protein) and INSIG-1. When cholesterol levels fall, INSIG-1 dissociates from the SREBP-SCAP complex, which allows the complex to migrate to the Golgi apparatus. Here SREBP is cleaved by S1P and S2P (site-1 protease and site-2 protease), two enzymes that are activated by SCAP when cholesterol levels are low.


title: Cholesterol

text: The cleaved SREBP then migrates to the nucleus and acts as a transcription factor to bind to the sterol regulatory element (SRE), which stimulates the transcription of many genes. Among these are the low-density lipoprotein (LDL) receptor and HMG-CoA reductase. The LDL receptor scavenges circulating LDL from the bloodstream, whereas HMG-CoA reductase leads to an increase in endogenous production of cholesterol. A large part of this signaling pathway was clarified by Dr. Michael S. Brown and Dr. Joseph L. Goldstein in the 1970s. In 1985, they received the Nobel Prize in Physiology or Medicine for their work. Their subsequent work shows how the SREBP pathway regulates the expression of many genes that control lipid formation and metabolism and body fuel allocation.


title: Cholesterol

text: Cholesterol synthesis can also be turned off when cholesterol levels are high. HMG-CoA reductase contains both a cytosolic domain (responsible for its catalytic function) and a membrane domain. The membrane domain senses signals for its degradation. Increasing concentrations of cholesterol (and other sterols) cause a change in this domain's oligomerization state, which makes it more susceptible to destruction by the proteasome. This enzyme's activity can also be reduced by phosphorylation by an AMP-activated protein kinase. Because this kinase is activated by AMP, which is produced when ATP is hydrolyzed, it follows that cholesterol synthesis is halted when ATP levels are low.


title: Cholesterol

text: As an isolated molecule, cholesterol is only minimally soluble in water, or hydrophilic. Because of this, it dissolves in blood at exceedingly small concentrations. To be transported effectively, cholesterol is instead packaged within lipoproteins, complex discoidal particles with exterior amphiphilic proteins and lipids, whose outward-facing surfaces are water-soluble and inward-facing surfaces are lipid-soluble. This allows it to travel through the blood via emulsification. Unbound cholesterol, being amphipathic, is transported in the monolayer surface of the lipoprotein particle along with phospholipids and proteins. Cholesterol esters bound to fatty acid, on the other hand, are transported within the fatty hydrophobic core of the lipoprotein, along with triglyceride.


title: Cholesterol

text: There are several types of lipoproteins in the blood. In order of increasing density, they are chylomicrons, very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). Lower protein/lipid ratios make for less dense lipoproteins. Cholesterol within different lipoproteins is identical, although some is carried as its native "free" alcohol form (the cholesterol-OH group facing the water surrounding the particles), while others as fatty acyl esters, known also as cholesterol esters, within the particles.


title: Cholesterol

text: Lipoprotein particles are organized by complex apolipoproteins, typically 80–100 different proteins per particle, which can be recognized and bound by specific receptors on cell membranes, directing their lipid payload into specific cells and tissues currently ingesting these fat transport particles. These surface receptors serve as unique molecular signatures, which then help determine fat distribution delivery throughout the body.


title: Cholesterol

text: Chylomicrons, the least dense cholesterol transport molecules, contain apolipoprotein B-48, apolipoprotein C, and apolipoprotein E (the principal cholesterol carrier in the brain) in their shells. Chylomicrons carry fats from the intestine to muscle and other tissues in need of fatty acids for energy or fat production. Unused cholesterol remains in more cholesterol-rich chylomicron remnants, and taken up from here to the bloodstream by the liver.


title: Cholesterol

text: VLDL molecules are produced by the liver from triacylglycerol and cholesterol which was not used in the synthesis of bile acids. These molecules contain apolipoprotein B100 and apolipoprotein E in their shells, and can be degraded by lipoprotein lipase on the artery wall to IDL. This arterial wall cleavage allows absorption of triacylglycerol and increases the concentration of circulating cholesterol. IDL molecules are then consumed in two processes: half is metabolized by HTGL and taken up by the LDL receptor on the liver cell surfaces, while the other half continues to lose triacylglycerols in the bloodstream until they become cholesterol-laden LDL particles.


title: Cholesterol

text: LDL particles are the major blood cholesterol carriers. Each one contains approximately 1,500 molecules of cholesterol ester. LDL molecule shells contain just one molecule of apolipoprotein B100, recognized by LDL receptors in peripheral tissues. Upon binding of apolipoprotein B100, many LDL receptors concentrate in clathrin-coated pits. Both LDL and its receptor form vesicles within a cell via endocytosis. These vesicles then fuse with a lysosome, where the lysosomal acid lipase enzyme hydrolyzes the cholesterol esters. The cholesterol can then be used for membrane biosynthesis or esterified and stored within the cell, so as to not interfere with the cell membranes.


title: Cholesterol

text: LDL receptors are used up during cholesterol absorption, and its synthesis is regulated by SREBP, the same protein that controls the synthesis of cholesterol "de novo", according to its presence inside the cell. A cell with abundant cholesterol will have its LDL receptor synthesis blocked, to prevent new cholesterol in LDL molecules from being taken up. Conversely, LDL receptor synthesis proceeds when a cell is deficient in cholesterol.


title: Cholesterol

text: When this process becomes unregulated, LDL molecules without receptors begin to appear in the blood. These LDL molecules are oxidized and taken up by macrophages, which become engorged and form foam cells. These foam cells often become trapped in the walls of blood vessels and contribute to atherosclerotic plaque formation. Differences in cholesterol homeostasis affect the development of early atherosclerosis (carotid intima-media thickness). These plaques are the main causes of heart attacks, strokes, and other serious medical problems, leading to the association of so-called LDL cholesterol (actually a lipoprotein) with "bad" cholesterol.


title: Cholesterol

text: HDL particles are thought to transport cholesterol back to the liver, either for excretion or for other tissues that synthesize hormones, in a process known as reverse cholesterol transport (RCT). Large numbers of HDL particles correlates with better health outcomes, whereas low numbers of HDL particles is associated with atheromatous disease progression in the arteries.


title: Cholesterol

text: Cholesterol is susceptible to oxidation and easily forms oxygenated derivatives called oxysterols. Three different mechanisms can form these: autoxidation, secondary oxidation to lipid peroxidation, and cholesterol-metabolizing enzyme oxidation. A great interest in oxysterols arose when they were shown to exert inhibitory actions on cholesterol biosynthesis. This finding became known as the "oxysterol hypothesis". Additional roles for oxysterols in human physiology include their participation in bile acid biosynthesis, function as transport forms of cholesterol, and regulation of gene transcription.


title: Cholesterol

text: In biochemical experiments radiolabelled forms of cholesterol, such as tritiated-cholesterol are used. These derivatives undergo degradation upon storage and it is essential to purify cholesterol prior to use. Cholesterol can be purified using small Sephadex LH-20 columns.


title: Cholesterol

text: Cholesterol is oxidized by the liver into a variety of bile acids. These, in turn, are conjugated with glycine, taurine, glucuronic acid, or sulfate. A mixture of conjugated and nonconjugated bile acids, along with cholesterol itself, is excreted from the liver into the bile. Approximately 95% of the bile acids are reabsorbed from the intestines, and the remainder are lost in the feces. The excretion and reabsorption of bile acids forms the basis of the enterohepatic circulation, which is essential for the digestion and absorption of dietary fats. Under certain circumstances, when more concentrated, as in the gallbladder, cholesterol crystallises and is the major constituent of most gallstones (lecithin and bilirubin gallstones also occur, but less frequently). Every day, up to 1 g of cholesterol enters the colon. This cholesterol originates from the diet, bile, and desquamated intestinal cells, and can be metabolized by the colonic bacteria. Cholesterol is converted mainly into coprostanol, a nonabsorbable sterol that is excreted in the feces.


title: Cholesterol

text: Although cholesterol is a steroid generally associated with mammals, the human pathogen "Mycobacterium tuberculosis" is able to completely degrade this molecule and contains a large number of genes that are regulated by its presence. Many of these cholesterol-regulated genes are homologues of fatty acid β-oxidation genes, but have evolved in such a way as to bind large steroid substrates like cholesterol.


title: Cholesterol

text: Animal fats are complex mixtures of triglycerides, with lesser amounts of both the phospholipids and cholesterol molecules from which all animal (and human) cell membranes are constructed. Since all animal cells manufacture cholesterol, all animal-based foods contain cholesterol in varying amounts. Major dietary sources of cholesterol include red meat, egg yolks and whole eggs, liver, kidney, giblets, fish oil, and butter. Human breast milk also contains significant quantities of cholesterol.


title: Cholesterol

text: Plant cells synthesize cholesterol as a precursor for other compounds, such as phytosterols and steroidal glycoalkaloids, with cholesterol remaining in plant foods only in minor amounts or absent. Some plant foods, such as avocado, flax seeds and peanuts, contain phytosterols, which compete with cholesterol for absorption in the intestines, and reduce the absorption of both dietary and bile cholesterol. A typical diet contributes on the order of 0.2 gram of phytosterols, which is not enough to have a significant impact on blocking cholesterol absorption. Phytosterols intake can be supplemented through the use of phytosterol-containing functional foods or dietary supplements that are recognized as having potential to reduce levels of LDL-cholesterol.


title: Cholesterol

text: In 2015, the United States Department of Agriculture Dietary Guidelines Advisory Committee (DGAC) recommended that Americans eat as little dietary cholesterol as possible, because most foods that are rich in cholesterol are also high in saturated fat and thereby may increase the risk of cardiovascular disease.


title: Cholesterol

text: A 2013 report by the American Heart Association and the American College of Cardiology recommended focusing on healthy dietary patterns rather than specific cholesterol limits, as they are hard for clinicians and consumers to implement. They recommend the DASH and Mediterranean diet, which are low in cholesterol. A 2017 review by the American Heart Association recommends switching saturated fats for polyunsaturated fats to reduce cardiovascular disease risk.


title: Cholesterol

text: Some supplemental guidelines have recommended doses of phytosterols in the 1.6–3.0 grams per day range (Health Canada, EFSA, ATP III, FDA). A recent meta-analysis demonstrating a 12% reduction in LDL-cholesterol at a mean dose of 2.1 grams per day. However, the benefits of a diet supplemented with phytosterols have also been questioned.


title: Cholesterol

text: According to the lipid hypothesis, elevated levels of cholesterol in the blood lead to atherosclerosis which may increase the risk of heart attack, stroke, and peripheral artery disease. Since higher blood LDL – especially higher LDL concentrations and smaller LDL particle size – contributes to this process more than the cholesterol content of the HDL particles, LDL particles are often termed "bad cholesterol". High concentrations of functional HDL, which can remove cholesterol from cells and atheromas, offer protection and are commonly referred to as "good cholesterol". These balances are mostly genetically determined, but can be changed by body composition, medications, diet, and other factors. A 2007 study demonstrated that blood total cholesterol levels have an exponential effect on cardiovascular and total mortality, with the association more pronounced in younger subjects. Because cardiovascular disease is relatively rare in the younger population, the impact of high cholesterol on health is larger in older people.


title: Cholesterol

text: Elevated levels of the lipoprotein fractions, LDL, IDL and VLDL, rather than the total cholesterol level, correlate with the extent and progress of atherosclerosis. Conversely, the total cholesterol can be within normal limits, yet be made up primarily of small LDL and small HDL particles, under which conditions atheroma growth rates are high. A "post hoc" analysis of the IDEAL and the EPIC prospective studies found an association between high levels of HDL cholesterol (adjusted for apolipoprotein A-I and apolipoprotein B) and increased risk of cardiovascular disease, casting doubt on the cardioprotective role of "good cholesterol".


title: Cholesterol

text: About one in 250 individuals can have a genetic mutation for the LDL cholesterol receptor that causes them to have familial hypercholesterolemia. Inherited high cholesterol can also include genetic mutations in the PCSK9 gene and the gene for apolipoprotein B.


title: Cholesterol

text: Elevated cholesterol levels are treated with a strict diet consisting of low saturated fat, trans fat-free, low cholesterol foods, often followed by one of various hypolipidemic agents, such as statins, fibrates, cholesterol absorption inhibitors, monoclonal antibody therapy (PCSK9 inhibitors), nicotinic acid derivatives or bile acid sequestrants. There are several international guidelines on the treatment of hypercholesterolaemia.


title: Cholesterol

text: Human trials using HMG-CoA reductase inhibitors, known as statins, have repeatedly confirmed that changing lipoprotein transport patterns from unhealthy to healthier patterns significantly lowers cardiovascular disease event rates, even for people with cholesterol values currently considered low for adults. Studies have shown that reducing LDL cholesterol levels by about 38.7 mg/dL with the use of statins can reduce cardiovascular disease and stroke risk by about 21%. Studies have also found that statins reduce atheroma progression. As a result, people with a history of cardiovascular disease may derive benefit from statins irrespective of their cholesterol levels (total cholesterol below 5.0 mmol/L [193 mg/dL]), and in men without cardiovascular disease, there is benefit from lowering abnormally high cholesterol levels ("primary prevention"). Primary prevention in women was originally practiced only by extension of the findings in studies on men, since, in women, none of the large statin trials conducted prior to 2007 demonstrated a significant reduction in overall mortality or in cardiovascular endpoints. Meta-analyses have demonstrated significant reductions in all-cause and cardiovascular mortality, without significant heterogeneity by sex.


title: Cholesterol

text: The 1987 report of National Cholesterol Education Program, Adult Treatment Panels suggests the total blood cholesterol level should be: < 200 mg/dL normal blood cholesterol, 200–239 mg/dL borderline-high, > 240 mg/dL high cholesterol. The American Heart Association provides a similar set of guidelines for total (fasting) blood cholesterol levels and risk for heart disease: Statins are effective in lowering LDL cholesterol and widely used for primary prevention in people at high risk of cardiovascular disease, as well as in secondary prevention for those who have developed cardiovascular disease.


title: Cholesterol

text: More current testing methods determine LDL ("bad") and HDL ("good") cholesterol separately, allowing cholesterol analysis to be more nuanced. The desirable LDL level is considered to be less than 100 mg/dL (2.6 mmol/L), although a newer upper limit of 70 mg/dL (1.8 mmol/L) can be considered in higher-risk individuals based on some of the above-mentioned trials. A ratio of total cholesterol to HDL—another useful measure—of far less than 5:1 is thought to be healthier.


title: Cholesterol

text: Total cholesterol is defined as the sum of HDL, LDL, and VLDL. Usually, only the total, HDL, and triglycerides are measured. For cost reasons, the VLDL is usually estimated as one-fifth of the triglycerides and the LDL is estimated using the Friedewald formula (or a variant): estimated LDL = [total cholesterol] − [total HDL] − [estimated VLDL]. Direct LDL measures are used when triglycerides exceed 400 mg/dL. The estimated VLDL and LDL have more error when triglycerides are above 400 mg/dL.


title: Cholesterol

text: In the Framingham Heart Study, each 10 mg/dL (0.6 mmol/L) increase in total cholesterol levels increased 30-year overall mortality by 5% and CVD mortality by 9%. While subjects over the age of 50 had an 11% increase in overall mortality, and a 14% increase in cardiovascular disease mortality per 1 mg/dL (0.06 mmol/L) year drop in total cholesterol levels. The researchers attributed this phenomenon to reverse causation, whereby the disease itself increases risk of death, as well as changes a myriad of factors, such as weight loss and the inability to eat, which lower serum cholesterol. This effect was also shown in men of all ages and women over 50 in the Vorarlberg Health Monitoring and Promotion Programme. These groups were more likely to die of cancer, liver diseases, and mental diseases with very low total cholesterol, of 186 mg/dL (10.3 mmol/L) and lower. This result indicates the low-cholesterol effect occurs even among younger respondents, contradicting the previous assessment among cohorts of older people that this is a marker for frailty occurring with age.


title: Cholesterol

text: Abnormally low levels of cholesterol are termed "hypocholesterolemia". Research into the causes of this state is relatively limited, but some studies suggest a link with depression, cancer, and cerebral hemorrhage. In general, the low cholesterol levels seem to be a consequence, rather than a cause, of an underlying illness. A genetic defect in cholesterol synthesis causes Smith–Lemli–Opitz syndrome, which is often associated with low plasma cholesterol levels. Hyperthyroidism, or any other endocrine disturbance which causes upregulation of the LDL receptor, may result in hypocholesterolemia.