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73391672 | https://en.wikipedia.org/wiki/K2-18b | K2-18b | K2-18b, also known as EPIC 201912552 b, is an exoplanet orbiting the red dwarf K2-18, located away from Earth. The planet is a sub-Neptune about 2.6 times the radius of Earth, with a 33-day orbit within the star's habitable zone. This means it receives about a similar amount of starlight as the Earth receives from the Sun. Initially discovered with the Kepler space telescope, it was later observed by the James Webb Space Telescope (JWST) in order to study the planet's atmosphere.
In 2019 the presence of water vapour in K2-18b's atmosphere was reported, drawing attention to this system. In 2023, the JWST detected carbon dioxide and methane in the atmosphere of K2-18b. JWST’s data has been variously interpreted as indicating a water ocean planet with a hydrogen-rich atmosphere, and a gas-rich mini-Neptune. K2-18b has been studied as a potential habitable world that, temperature aside, more closely resembles a gas planet like Uranus or Neptune than Earth.
Host star
K2-18 is an M dwarf of the spectral class M3V in the constellation Leo, away from the Sun. The star is colder and smaller than the Sun, having a temperature of and a radius 45% of the Sun's, and is not visible to the naked eye. The star is 2.4 ± 0.6 billion years old and displays moderate stellar activity, but whether it has star spots, which would tend to create false signals when a planet crosses them, is unclear. K2-18 has an additional planet inside of K2-18b's orbit, K2-18c, which may interact with K2-18b through tides.
It is estimated that up to 80% of all M dwarf stars have planets in their habitable zones, including the stars LHS 1140, Proxima Centauri and TRAPPIST-1. The small mass, size and low temperatures of these stars and frequent orbits of the planets make it easier to characterize the planets. On the other hand, the low luminosity of the stars can make spectroscopic analysis of planets difficult, and the stars are frequently active with flares and inhomogeneous stellar surfaces (faculae and starspots), which can produce erroneous spectral signals when investigating a planet.
Physical properties
K2-18b has a radius of , a mass of , and orbits its star in 33 days. From Earth, it can be seen passing in front of the star. The planet is most likely tidally locked to the star, although considering its orbital eccentricity, a spin-orbit resonance like Mercury is also possible.
The density of K2-18b is about intermediate between Earth and Neptune implying that the planet has a hydrogen-rich envelope. The planet may either be rocky with a thick envelope or have a Neptune-like composition. A pure water planet with a thin atmosphere is less likely. Planets with radii of about are unexpectedly rare relative to their expected occurrence rate, a phenomenon known as the radius valley. Presumably, planets with intermediary radii cannot hold their atmospheres against the tendency of their own energy output and the stellar radiation to drive atmospheric escape. Planets with even smaller radii are known as Super-Earths and those with larger radii as Sub-Neptunes.
The planet may have taken a few million years to form. Tidal heating is unlikely. Internal heating may increase temperatures at large depths, but is unlikely to significantly affect the surface temperature. If an ocean exists, it is probably underlaid by a high-pressure ice layer on top of a rocky core, which might destabilize the planet's climate by preventing material flows between the core and the ocean.
Possible ocean
At temperatures exceeding the critical point, liquids and gases stop being different phases and there is no longer a separation between an ocean and the atmosphere. It is unclear whether observations imply that a separate liquid ocean exists on K2-18b, and detecting such an ocean is difficult from the outside; its existence cannot be inferred or ruled out solely from the mass and radius of a planet.
The existence of a liquid water ocean is uncertain. Before the James Webb Space Telescope observations, a supercritical state of the water was believed to be more likely. JWST observations were initially considered to be more consistent with a fluid-gas interface and thus a liquid ocean - trace gases such as hydrocarbons and ammonia can be lost from an atmosphere to an ocean if it exists; their presence may thus imply the absence of an ocean-atmosphere separation. Subsequent work finds that a magma ocean may also capable of dissolving ammonia and explaining the observation results, but not to explain the observed carbon oxide concentrations. Whether the carbon oxide concentrations can be explained by a mini-Neptune/deep hydrogen atmosphere model is uncertain. Another paper suggests that a liquid water ocean model requires the presence of a biosphere in order to produce sufficient amount of methane.
Atmosphere and climate
Observations with the Hubble Space Telescope have found that K2-18b has an atmosphere consisting of hydrogen. The presence of water vapour is likely but with uncertainty, as James Webb Space Telescope observations indicating concentrations of less than 0.1%; this may be due to the JWST seeing a dry stratosphere as the atmosphere is thought to have an efficient cold trap. Ammonia concentrations appear to be unmeasurably low. JWST observations indicate that methane and carbon dioxide each make up about 1% of the atmosphere. Other carbon oxides were not reported; only an upper limit to their concentrations (a few percent) has been established. The atmosphere makes up at most 6.2% of the planet's mass, and its composition probably resembles that of Uranus and Neptune.
There is little evidence of hazes in the atmosphere, while evidence for water clouds, the only kind of clouds likely to form at K2-18b, is conflicting. If they exist, the clouds are most likely icy but liquid water is possible. Apart from water, ammonium chloride, sodium sulfide, potassium chloride and zinc sulfide could form clouds in the atmosphere of K2-18b, depending on the planet's properties. Most computer models expect that a temperature inversion will form at high elevation, yielding a stratosphere.
Evolution
High-energy radiation from the star, such as hard UV radiation and X-rays, is expected to heat the upper atmosphere and fill it with hydrogen formed through the photodissociation of water, thus forming an extended hydrogen-rich exosphere that can escape from the planet. The X-ray and UV fluxes that K2-18b receives from K2-18 are considerably higher than the equivalent fluxes from the Sun; the hard UV radiation flux provides enough energy to drive this exosphere to escape at a rate of about tons per second, too slow to remove the planet's atmosphere during its lifespan. Observations of decreases of Lyman alpha radiation emissions during transits of the planet may show the presence of such an exosphere; this discovery requires confirmation.
Alternative scenarios
Detecting atmospheres around planets is difficult, and several reported findings are controversial. Barclay et al. 2021 suggested that the water vapour signal may be due to stellar activity, rather than water in K2-18b's atmosphere. Bézard et al. 2020 proposed that methane may be a more significant component, making up about 3–10% while water may constitute about 5–11% of the atmosphere, and Bézard, Charnay and Blain 2022 proposed that the evidence of water is actually due to methane, although such a scenario is less probable.
Models
Climate models have been used to simulate the climate that K2-18b might have, and an intercomparison of their results for K2-18b is part of the CAMEMBERT project to simulate the climates of sub-Neptune planets. Among the climate modelling efforts made on K2-18b are:
Charnay et al. 2021, assuming that the planet is tidally locked, found an atmosphere with weak temperature gradients and a wind system with descending air on the night side and ascending air on the day side. In the upper atmosphere, radiation absorption by methane produced an inversion layer. Clouds could only form if the atmosphere had a high metallicity; their properties strongly depended on the size of cloud particles and the composition and circulation of the atmosphere. They formed mainly at the substellar point and the terminator. If there was rainfall, it could not reach the surface; instead it evaporated to form virga. Simulations with a spin-orbit resonance did not substantially alter the cloud distribution. They also simulated the appearance of the atmosphere during stellar transits.
Innes and Pierrehumbert 2022 conducted simulations assuming different rotation rates and concluded that except for high rotation rates, there is not a substantial temperature gradient between poles and equator. They found the existence of jet streams above the equator and at high latitudes, with weaker equatorial jets at the surface.
Hu 2021 conducted simulations of the planet's chemistry. They concluded that the photochemistry should not be able to completely remove ammonia from the outer atmosphere and that carbon oxides and cyanide would form in the middle atmosphere, where they could be detectable. The model predicts that a sulfur haze layer could form, extending through and above the water clouds. Such a haze layer would make investigations of the planet's atmosphere much more difficult.
Tsai et al. 2024 ran chemical and physical models. They found a prograde jet stream in the troposphere and a retrograde one above altitude, with thermally-driven circulation in-between the two. Tentative detection of dimethyl sulfide was reported. Several hydrocarbons can mask the dimethyl sulfide signal, and its production needs to exceed Earth's by a factor of 20 to be detectable. Such a rate is possible for a plausible ecosystem.
Habitability
Incoming stellar radiation amounts to , similar to the average insolation Earth receives. K2-18b is located within or just slightly inside the habitable zone of its star, – it may be close to but fall short of the runaway greenhouse threshold – and its temperature in the absence of a greenhouse is about to . Whether the planet is actually habitable depends on the nature of the atmosphere and the albedo of clouds and hazes; the deeper layers of the atmosphere may be too hot, while the water-containing layers might or might not have temperatures and pressures suitable for the development of life.
Microorganisms from Earth can survive in hydrogen-rich atmospheres, illustrating that hydrogen is no impediment to life. However, a number of biosignature gases used to identify the presence of life are not reliable indicators when found in a hydrogen-rich atmosphere, thus different markers would be needed to identify biological activity at K2-18b. According to Madhusudhan et al., several of these markers could be detected by the James Webb Space Telescope after a reasonable number of observations.
Discovery and research history
The planet was discovered in 2015 by the Kepler space telescope, and its existence was later confirmed with the Spitzer Space Telescope and through Doppler velocity techniques. Analyses of the transits ruled out that they were caused by unseen companion stars, by multiple planets or systematic errors of the observations. Early estimates of the star's radius had substantial errors, which led to incorrect planet radius estimates and the density of the planet being overestimated. The discovery of the spectroscopic signature of water vapour on K2-18b in 2019 was the first discovery of water vapour on an exoplanet that is not a Hot Jupiter and drew a lot of discussion.
K2-18b has been used as a test case for exoplanet studies. The properties of K2-18b have led to the definition of a "hycean planet", a type of planet that has both abundant liquid water and a hydrogen envelope. Planets with such compositions were previously thought to be too hot to be habitable; findings at K2-18b instead suggest that they might be cold enough to harbour liquid water oceans conducive to life. The strong greenhouse effect of the hydrogen envelope might allow them to remain habitable even at low instellation rates. K2-18b is probably the best known "hycean planet". Other, non-hycean compositions are possible, both habitable and uninhabitable.
There is some evidence of dimethyl sulfide (DMS) and methyl chloride being present in the atmosphere. The presence of DMS is a potential biosignature, as the bulk of the DMS in Earth's atmosphere is emitted from phytoplankton in marine environments, although further observation to confirm the presence of DMS and rule out a geological or chemical origin for the compound is required. Some scientists have voiced concerns about the statistical significance of the DMS signal at K2-18b, and how its putative detection might be understood in an environment different than Earth. In 2024, Wogan et al. suggested that the high methane concentrations might either imply the presence of methanogenic life or upwards mixing of gases from the deep interior, if the planet is too hot for life.
A podcast on the Planetary Society's website in January 2024 featured NASA astrophysicist Knicole Colón describing some of the scientific results from the observations of K2-18b by JWST. Data from JWST's MIRI instrument was expected to be gathered in January 2024 about which Colón said: "MIRI will be able to see additional features, absorption features from these molecules, and validate again, the presence of what we've seen and even the abundance." Colón also talks about the lack of evidence of water in the atmosphere: "The fact that the JWST data basically didn't find strong evidence of water in the atmosphere, that could indicate a couple things". Further, two observations using MIRI which lasted over 8 hours were taken on 25 & 26 April 2024 as part of JWST project 2722.
| Physical sciences | Notable exoplanets | Astronomy |
62390939 | https://en.wikipedia.org/wiki/Volcanic%20crater%20lake | Volcanic crater lake | A volcanic crater lake is a lake in a crater that was formed by explosive activity or a collapse during a volcanic eruption.
Formation
Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars fill medium-sized craters where an eruption deposited debris around a vent.
Crater lakes form as the created depression, within the crater rim, is filled by water. The water may come from precipitation, groundwater circulation (often hydrothermal fluids in the case of volcanic craters) or melted ice. Its level rises until an equilibrium is reached between the rates of incoming and outgoing water. Sources of water loss singly or together may include evaporation, subsurface seepage, and, in places, surface leakage or overflow when the lake level reaches the lowest point on its rim. At such a saddle location, the upper portion of the lake is contained only by its adjacent natural volcanic dam; continued leakage through or surface outflow across the dam can erode its included material, thus lowering lake level until a new equilibrium of water flow, erosion, and rock resistance is established. If the volcanic dam portion erodes rapidly or fails catastrophically, the occurrence produces a breakout or outburst flood. With changes in environmental conditions over time, the occurrence of such floods is common to all natural dam types.
These lakes may become soda lakes, many of which are associated with active tectonic and volcanic zones.
Examples
A well-known crater lake, which bears the same name as the geological feature, is Crater Lake in Oregon. It is located in the caldera of Mount Mazama. It is the deepest lake in the United States with a depth of . Crater Lake is fed solely by falling rain and snow, with no inflow or outflow at the surface, and hence is one of the clearest lakes in the world.
The highest volcano in the world, 6,893-m (22,615-ft) Ojos del Salado in Chile, has a permanent crater lake about in diameter at an elevation of on its eastern side. This is most likely the highest lake of any kind in the world.
Due to their unstable environments, some crater lakes exist only intermittently. Caldera lakes in contrast can be quite large and long-lasting. For instance, Lake Toba in Indonesia formed after its eruption around 75,000 years ago. At around by in extent and deep at its deepest point, Lake Toba is the largest crater lake in the world.
Dangers
While many crater lakes are picturesque, they can also be deadly. Gas discharges from Lake Nyos in Cameroon suffocated 1,800 people in 1986, and crater lakes such as Mount Ruapehu's in New Zealand often contribute to destructive lahars.
Distinction from other volcanic lakes
Certain bodies of water, although their formation is directly related to volcanic activity, are not usually referred to as crater lakes, including:
Lakes created by volcanic dams due to lava flowing outside of the volcanic edifice/caldera, such as Garibaldi Lake in Canada, Fuji Five Lakes in Japan
Closed atoll lagoons, such as Clipperton lagoon, whose formation process also implies subsequent biogeomorphologic processes
Ponds encountered at the bottom of waterfalls occurring in volcanic canyons in a volcanic context, but not within a volcanic edifice/caldera (such as Trou de Fer on Réunion Island)
List
Africa
Antarctica and the sub-Antarctic islands
Asia
Europe
North America
Oceania
South America
| Physical sciences | Hydrology | Earth science |
63297153 | https://en.wikipedia.org/wiki/Perseverance%20%28rover%29 | Perseverance (rover) | Perseverance is a car-sized Mars rover designed to explore the Jezero crater on Mars as part of NASA's Mars 2020 mission. It was manufactured by the Jet Propulsion Laboratory and launched on July 30, 2020, at 11:50 UTC. Confirmation that the rover successfully landed on Mars was received on February 18, 2021, at 20:55 UTC. As of , Perseverance has been active on Mars for sols ( Earth days, or ) since its landing. Following the rover's arrival, NASA named the landing site Octavia E. Butler Landing.
Perseverance has a similar design to its predecessor rover, Curiosity, although it was moderately upgraded. It carries seven primary payload instruments, nineteen cameras, and two microphones.
The rover also carried the mini-helicopter Ingenuity to Mars, an experimental technology testbed that made the first powered aircraft flight on another planet on April 19, 2021. On January 18, 2024 (UTC), it made its 72nd and final flight, suffering damage on landing to its rotor blades, possibly all four, causing NASA to retire it.
The rover's goals include identifying ancient Martian environments capable of supporting life, seeking out evidence of former microbial life existing in those environments, collecting rock and soil samples to store on the Martian surface, and testing oxygen production from the Martian atmosphere to prepare for future crewed missions.
Mission
Despite the high-profile success of the Curiosity rover landing in August 2012, NASA's Mars Exploration Program was in a state of uncertainty in the early 2010s. Budget cuts forced NASA to pull out of a planned collaboration with the European Space Agency which included a rover mission. By the summer of 2012, a program that had been launching a mission to Mars every two years suddenly found itself with no missions approved after 2013.
In 2011, the Planetary Science Decadal Survey, a report from the National Academies of Sciences, Engineering, and Medicine containing an influential set of recommendations made by the planetary science community, stated that the top priority of NASA's planetary exploration program in the decade between 2013 and 2022 should be to begin a NASA-ESA Mars Sample Return campaign, a four-mission project to cache, retrieve, launch, and safely return samples of the Martian surface to Earth. The report stated that NASA should invest in a sample-caching rover as the first step in this effort, with the goal of keeping costs under US$2.5 billion.
After the success of the Curiosity rover and in response to the recommendations of the decadal survey, NASA announced its intent to launch a new Mars rover mission by 2020 at the American Geophysical Union conference in December 2012.
Though initially hesitant to commit to an ambitious sample-caching capability (and subsequent follow-on missions), a NASA-convened science definition team for the Mars 2020 project released a report in July 2013 that the mission should "select and store a compelling suite of samples in a returnable cache."
Science objectives
The Perseverance rover has four main science objectives that support the Mars Exploration Program's science goals:
Looking for habitability: identify past environments that were capable of supporting microbial life.
Seeking biosignatures: seek signs of possible past microbial life in those habitable environments, particularly in specific rock types known to preserve signs over time.
Caching samples: collect core rock and regolith (unconsolidated and loose "soil") samples and store them within the rover and on the Martian surface (as a backup) for delivery to a future sample return rocket.
Preparing for humans: test oxygen production from the Martian atmosphere.
In the first science campaign, dubbed "Crater Floor", Perseverance performed an arching drive southward from its landing site to the Séítah unit to perform a "toe dip" into the unit to collect remote-sensing measurements of geologic targets. After that it returned to the Crater Floor Fractured Rough to collect the first core sample there. Passing by the Octavia E. Butler landing site concluded the first science campaign.
The second campaign, "Fan Front", included several months of travel towards the "Three Forks" where Perseverance accessed geologic locations at the base of the ancient delta of Neretva river, as well as ascending the delta by driving up a valley wall to the northwest.
The third and fourth campaigns were called “Upper Fan,” and “Margin Unit", and the fifth campaign, "Northern Rim", in progress as of December 2024, is exploring "the northern part of the southwestern section of Jezero’s rim" to study "rocks from deep down inside Mars that were thrown upward to form the crater rim" after the impact 3.9 billion years ago that formed Jezero Crater
Results
The scientific results, as of 2025, are as follows. According to NASA, the mission has made "discoveries about the volcanic history, habitability, and role of water in Jezero Crater." Specifically, they reported that instead of all the rocks in Jezero crater being sedimentary, being "transported into the crater by wind or water," "several types of igneous rock" were discovered, which "showed evidence of interaction with water." Additionally,
They also found that "sediments entering Jezero's lake were deposited in a delta" and "evidence for late-stage, high-energy flooding that carried large boulders into the crater." The MOXIE experiment produced 122 grams of oxygen from carbon dioxide. The microphone studies showed that the speed of sound is slower and the volumes of sounds transmitted through the atmosphere is lower, than on Earth..
PIXL found that the Seitah formation and a rock at "Otis Peak" contained olivine, phosphates, sulfates, clays, carbonate minerals, silicate minerals, "augite pyroxene, feldspathic mesostasis, various Fe,Cr,Ti-spinels, and merrillite", perchlorate, feldspar, magnesite, siderite, oxides, as well as minerals with composition including magnesium, iron, chlorine, and sodium.
RIMFAX revealed findings "consistent with a subsurface dominated by solid rock and mafic material" and that "the crater floor experienced a period of erosion before the deposition of the overlying delta strata. The regularity and horizontality of the basal delta sediments observed in the radar cross sections indicate that they were deposited in a low-energy lake environment."
Design
The Perseverance design evolved from its predecessor, the Curiosity rover. The two rovers share a similar body plan, landing system, cruise stage, and power system, but the design was improved in several ways for Perseverance. Engineers designed the rover wheels to be more robust than Curiosity wheels, which had sustained some damage. Perseverance has thicker, more durable aluminum wheels, with reduced width and a greater diameter, , than Curiosity wheels. The aluminum wheels are covered with cleats for traction and curved titanium spokes for springy support. The heat shield for the rover was made out of phenolic-impregnated carbon ablator (PICA), to allow it to withstand up to of heat. Like Curiosity, the rover includes a robotic arm, although Perseverances arm is longer and stronger, measuring . The arm hosts an elaborate rock-coring and sampling mechanism to store geologic samples from the Martian surface in sterile caching tubes. There is also a secondary arm hidden below the rover that helps store the chalk-sized samples. This arm is known as the Sample Handling Assembly (SHA), and is responsible for moving the soil samples to various stations within the Adaptive Caching Assembly (ACA) on the underside of the rover. These stations include volume assessment (measuring the length of sample), imaging, seal dispensing, and hermetic seal station, among others. Owing to the small space in which the SHA must operate, as well as load requirements during sealing activities, the Sample Caching System "is the most complicated, most sophisticated mechanism that we have ever built, tested and readied for spaceflight."
The combination of larger instruments, new sampling and caching system, and modified wheels makes Perseverance heavier, weighing compared to Curiosity at —a 14% increase.
The rover's multi-mission radioisotope thermoelectric generator (MMRTG) has a mass of and uses of plutonium-238 oxide as its power source. The radioactive decay of plutonium-238, which has a half-life of 87.7 years, gives off heat which is converted to electricity—approximately 110 watts at launch. This will decrease over time as its power source decays. The MMRTG charges two lithium-ion rechargeable batteries which power the rover's activities, and must be recharged periodically. Unlike solar panels, the MMRTG provides engineers with significant flexibility in operating the rover's instruments even at night, during dust storms, and through winter.
The rover's computer uses the BAE Systems RAD750 radiation-hardened single board computer based on a ruggedized PowerPC G3 microprocessor (PowerPC 750). The computer contains 128 megabytes of volatile DRAM, and runs at 133 MHz. The flight software runs on the VxWorks operating system, is written in C and is able to access 4 gigabytes of NAND non-volatile memory on a separate card. Perseverance relies on three antennas for telemetry, all of which are relayed through craft currently in orbit around Mars. The primary UHF antenna can send data from the rover at a maximum rate of two megabits per second. Two slower X-band antennas provide communications redundancy.
Instruments
NASA considered nearly 60 proposals for rover instrumentation. On July 31, 2014, NASA announced the seven instruments that would make up the payload for the rover:
Mars Oxygen ISRU Experiment (MOXIE), an exploration technology investigation to produce a small amount of oxygen () from Martian atmospheric carbon dioxide (). On April 20, 2021, 5.37 grams of oxygen were produced in an hour, with nine more extractions planned over the course of two Earth years to further investigate the instrument. This technology could be scaled up in the future for human life support or to make the rocket fuel for return missions.
Planetary Instrument for X-Ray Lithochemistry (PIXL), an X-ray fluorescence spectrometer to determine the fine scale elemental composition of Martian surface materials.
Radar Imager for Mars' subsurface experiment (RIMFAX), a ground-penetrating radar to image different ground densities, structural layers, buried rocks, meteorites, and detect underground water ice and salty brine at depth. The RIMFAX is being provided by the Norwegian Defence Research Establishment (FFI).
Mars Environmental Dynamics Analyzer (MEDA), a set of sensors that measure temperature, wind speed and direction, pressure, relative humidity, radiation, and dust particle size and shape. It is provided by Spain's Centro de Astrobiología.
SuperCam, an instrument suite that can provide imaging, chemical composition analysis, and mineralogy in rocks and regolith from a distance. It is an upgraded version of the ChemCam on the Curiosity rover but with two lasers and four spectrometers that will allow it to remotely identify biosignatures and assess the past habitability. SuperCam is used in conjunction with the AEGIS targeting system. Los Alamos National Laboratory, the Research Institute in Astrophysics and Planetology (IRAP) in France, the French Space Agency (CNES), the University of Hawaii, and the University of Valladolid in Spain cooperated in the SuperCam's development and manufacture.
Mastcam-Z, a stereoscopic imaging system with the ability to zoom. Many photos were included in the published NASA photogallery. (Including Raw)
Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC), an ultraviolet Raman spectrometer that uses fine-scale imaging and an ultraviolet (UV) laser to determine fine-scale mineralogy and detect organic compounds.
There are additional cameras and two audio microphones (the first working microphones on Mars), that will be used for engineering support during landing, driving, and collecting samples. For a full look at Perseverances components see Learn About the Rover.
Mars Ingenuity helicopter experiment
The Ingenuity helicopter, powered by solar-charged batteries, was sent to Mars in the same bundle with Perseverance. With a mass of , the helicopter demonstrated the reality of flight in the rarefied Martian atmosphere and the potential usefulness of aerial scouting for rover missions. It carried two cameras but no scientific instruments and communicated with Earth via a base station onboard Perseverance. Its pre-launch experimental test plan was three flights in 45 days, but it far exceeded expectations and made 72 flights in nearly three years. After its first few flights, it made incrementally more ambitious ones, several of which were recorded by Perseverances cameras. The first flight was April 19, 2021, at 07:15 UTC, with confirmation from data reception at 10:15 UTC. It was the first powered flight by any aircraft on another planet. On January 18, 2024 (UTC), it made its 72nd and final flight, suffering the loss of a rotor blade (imaged, by Perseverance, lying on the sand roughly distant from the upright body of Ingenuity), causing NASA to retire it.
Name
Associate Administrator of NASA's Science Mission Directorate, Thomas Zurbuchen selected the name Perseverance following a nationwide K-12 student "name the rover" contest that attracted more than 28,000 proposals. A seventh-grade student, Alexander Mather from Lake Braddock Secondary School in Burke, Virginia, submitted the winning entry at the Jet Propulsion Laboratory. In addition to the honor of naming the rover, Mather and his family were invited to NASA's Kennedy Space Center to watch the rover's July 2020 launch from Cape Canaveral Air Force Station (CCAFS) in Florida.
Mather wrote in his winning essay:Curiosity. InSight. Spirit. Opportunity. If you think about it, all of these names of past Mars rovers are qualities we possess as humans. We are always curious, and seek opportunity. We have the spirit and insight to explore the Moon, Mars, and beyond. But, if rovers are to be the qualities of us as a race, we missed the most important thing. Perseverance. We as humans evolved as creatures who could learn to adapt to any situation, no matter how harsh. We are a species of explorers, and we will meet many setbacks on the way to Mars. However, we can persevere. We, not as a nation but as humans, will not give up. The human race will always persevere into the future.
Twin rover
JPL built a copy of the Perseverance; a twin rover used for testing and problem solving, OPTIMISM (Operational Perseverance Twin for Integration of Mechanisms and Instruments Sent to Mars), a vehicle system test bed (VSTB). It is housed at the JPL Mars Yard and is used to test operational procedures and to aid in problem solving should any issues arise with Perseverance.
Operational history
Mars transit
The Perseverance rover lifted off successfully on July 30, 2020, at 11:50:00 UTC aboard a United Launch Alliance Atlas V launch vehicle from Space Launch Complex 41, at Cape Canaveral Air Force Station (CCAFS) in Florida.
The rover took 29 weeks to travel to Mars and made its landing in Jezero Crater on February 18, 2021, to begin its science phase.
After May 17, 2022, the rover will move uphill and examine rocks on the surface for evidence of past life on Mars. On its return downhill, it will collect sample rocks to be retrieved and examined by future expeditions.
Landing
The successful landing of Perseverance in Jezero Crater was announced at 20:55 UTC on February 18, 2021, the signal from Mars taking 11 minutes to arrive at Earth. The rover touched down at , roughly southeast of the center of its wide landing ellipse. It came down pointed almost directly to the southeast, with the RTG on the back of the vehicle pointing northwest. The descent stage ("sky crane"), parachute and heat shield all came to rest within 1.5 km of the rover (see satellite image). Having come within of its target, the landing was more accurate than any previous Mars landing; a feat enabled by the experience gained from Curiositys landing and the use of new steering technology.
One such new technology is Terrain Relative Navigation (TRN), a technique in which the rover compares images of the surface taken during its descent with reference maps, allowing it to make last minute adjustments to its course. The rover also uses the images to select a safe landing site at the last minute, allowing it to land in relatively unhazardous terrain. This enables it to land much closer to its science objectives than previous missions, which all had to use a landing ellipse devoid of hazards.
The landing occurred in the late afternoon, with the first images taken at 15:53:58 on the mission clock (local mean solar time). The landing took place shortly after Mars passed through its northern vernal equinox (Ls = 5.2°), at the start of the astronomical spring, the equivalent of the end of March on Earth.
The parachute descent of the Perseverance rover was photographed by the HiRISE high-resolution camera on the Mars Reconnaissance Orbiter (MRO).
Jezero Crater is a paleolake basin. It was selected as the landing site for this mission in part because paleolake basins tend to contain perchlorates. Astrobiologist Dr. Kennda Lynch's work in analog environments on Earth suggests that the composition of the crater, including the bottomset deposits accumulated from three different sources in the area, is a likely place to discover evidence of perchlorate-reducing microbes, if such bacteria are living or were formerly living on Mars.
A few days after landing, Perseverance released the first audio recorded on the surface of Mars, capturing the sound of Martian wind.
During its travels on Mars, NASA scientists had observed around Sol 341 (February 4, 2022) that a small rock had dropped into one of its wheels while the rover was studying the Máaz rock formation. The rock was visible from one of the hazard avoidance cameras, and was determined not to be harmful to the rover's mission. The rock has since stayed on Perseverances wheel for around 427 sols (439 days) as the rover traveled over on the martian surface. NASA deemed that Perseverance had adopted a pet rock for its journey. Later, by May 2024, the rover picked up another pet rock named "Dwayne".
Traverse
It is planned for Perseverance to visit the bottom and upper parts of the 3.4 to 3.8 billion-year-old Neretva Vallis delta, the smooth and etched parts of the Jezero Crater floor deposits interpreted as volcanic ash or aeolian airfall deposits, emplaced before the formation of the delta; the ancient shoreline covered with Transverse Aeolian Ridges (dunes) and mass wasting deposits, and finally, it is planned to climb onto the Jezero Crater rim.
In its progressive commissioning and tests, Perseverance made its first test drive on Mars on March 4, 2021. NASA released photographs of the rover's first wheel tracks on the Martian soil.
Samples cached for the Mars sample-return mission
In support of the NASA-ESA Mars Sample Return, rock, regolith (Martian soil), and atmosphere samples are being cached by Perseverance. As of October 2023, 27 out of 43 sample tubes have been filled, including 8 igneous rock samples, 12 sedimentary rock sample tubes, a Silica-cemented carbonate rock sample tube, two regolith sample tubes, an atmosphere sample tube, and three witness tubes. Before launch, 5 of the 43 tubes were designated "witness tubes" and filled with materials that would capture particulates in the ambient environment of Mars. Out of 43 tubes, 3 witness sample tubes will not be returned to Earth and will remain on rover as the sample canister will only have 30 tube slots. Further, 10 of the 43 tubes are left as backups at the Three Forks Sample Depot.
Discoveries
In July 2024, NASA’s Perseverance rover discovered “leopard spots” on a reddish rock nicknamed "Cheyava Falls" in Mars’ Jezero Crater, that has some indications it may have hosted microbial life billions of years ago, but further research is needed.
Cost
NASA plans to invest roughly US$2.75 billion in the project over 11 years, including US$2.2 billion for the development and building of the hardware, US$243 million for launch services, and US$291 million for 2.5 years of mission operations.
Adjusted for inflation, Perseverance is NASA's sixth-most expensive robotic planetary mission, though it is cheaper than its predecessor, Curiosity. Perseverance benefited from spare hardware and "build-to print" designs from the Curiosity mission, which helped reduce development costs and saved "probably tens of millions, if not 100 million dollars" according to Mars 2020 Deputy Chief Engineer Keith Comeaux.
Commemorative artifacts
"Send Your Name to Mars"
NASA's "Send Your Name to Mars" campaign invited people from around the world to submit their names to travel aboard the agency's next rover to Mars. 10,932,295 names were submitted. The names were etched by an electron beam onto three fingernail-sized silicon chips, along with the essays of the 155 finalists in NASA's "Name the Rover" contest. The three chips share space on an anodized plate with a laser engraved graphic representing Earth, Mars, and the Sun. The rays emanating from the Sun contain the phrase "Explore As One" written in Morse code. The plate was then mounted on the rover on March 26, 2020.
Geocaching in Space Trackable
Part of Perseverances cargo is a geocaching trackable item viewable with the SHERLOC's WATSON camera.
In 2016, NASA SHERLOC co-investigator Dr. Marc Fries — with help from his son Wyatt — was inspired by Geocaching's 2008 placement of a cache on the International Space Station to set out and try something similar with the rover mission. After floating the idea around mission management, it eventually reached NASA scientist Francis McCubbin, who would join the SHERLOC instrument team as a collaborator to move the project forward. The Geocaching inclusion was scaled-down to a trackable item that players could search for from NASA camera views and then log on to the site. In a manner similar to the "Send Your Name to Mars" campaign, the geocaching trackable code was carefully printed on a one-inch, polycarbonate glass disk serving as part of the rover's calibration target. It will serve as an optical target for the WATSON imager and a spectroscopic standard for the SHERLOC instrument. The disk is made of a prototype astronaut helmet visor material that will be tested for its potential use in crewed missions to Mars. Designs were approved by the mission leads at NASA's Jet Propulsion Laboratory (JPL), NASA Public Affairs, and NASA HQ, in addition to Groundspeak Geocaching HQ.
Tribute to healthcare workers
Perseverance launched during the COVID-19 pandemic, which began to affect the mission planning in March 2020. To show appreciation for healthcare workers who helped during the pandemic, an plate with a staff-and-serpent symbol (a Greek symbol of medicine) was placed on the rover. The project manager, Matt Wallace, said he hoped that future generations going to Mars would be able to appreciate healthcare workers during 2020.
Family portrait of NASA Mars rovers
One of the external plates of Perseverance includes a simplified representation of all previous NASA Martian rovers, Sojourner, Spirit, Opportunity, Curiosity, as well as Perseverance and Ingenuity, similar to the trend of automobile window decals used to show a family's makeup.
Parachute with coded message
The orange-and-white parachute used to land the rover on Mars contained a coded message that was deciphered by Twitter users. NASA's systems engineer Ian Clark used binary code to hide the message "dare mighty things" in the parachute color pattern. The parachute consisted of 80 strips of fabric that form a hemisphere-shape canopy, and each strip consisted of four pieces. Dr. Clark thus had 320 pieces with which to encode the message. He also included the GPS coordinates for the Jet Propulsion Laboratory's headquarters in Pasadena, California (34°11’58” N 118°10’31” W). Clark said that only six people knew about the message before landing. The code was deciphered a few hours after the image was presented by Perseverances team.
"Dare mighty things" is a quote attributed to U.S. president Theodore Roosevelt and is the unofficial motto of the Jet Propulsion Laboratory. It adorns many of the JPL center's walls.
NASA outreach to students
In December 2021, the NASA team announced a program to students who have persevered with academic challenges. Those nominated will be rewarded with a personal message beamed back from Mars by the Perseverance rover.
Gallery
March 5, 2024: NASA released images of transits of the moon Deimos, the moon Phobos and the planet Mercury as viewed by the Perseverance rover on the planet Mars.
| Technology | Rovers | null |
58071309 | https://en.wikipedia.org/wiki/Unitary%20transformation%20%28quantum%20mechanics%29 | Unitary transformation (quantum mechanics) | In quantum mechanics, the Schrödinger equation describes how a system changes with time. It does this by relating changes in the state of the system to the energy in the system (given by an operator called the Hamiltonian). Therefore, once the Hamiltonian is known, the time dynamics are in principle known. All that remains is to plug the Hamiltonian into the Schrödinger equation and solve for the system state as a function of time.
Often, however, the Schrödinger equation is difficult to solve (even with a computer). Therefore, physicists have developed mathematical techniques to simplify these problems and clarify what is happening physically. One such technique is to apply a unitary transformation to the Hamiltonian. Doing so can result in a simplified version of the Schrödinger equation which nonetheless has the same solution as the original.
Transformation
A unitary transformation (or frame change) can be expressed in terms of a time-dependent Hamiltonian and unitary operator . Under this change, the Hamiltonian transforms as:
.
The Schrödinger equation applies to the new Hamiltonian. Solutions to the untransformed and transformed equations are also related by . Specifically, if the wave function satisfies the original equation, then will satisfy the new equation.
Derivation
Recall that by the definition of a unitary matrix, . Beginning with the Schrödinger equation,
,
we can therefore insert the identity at will. In particular, inserting it after and also premultiplying both sides by , we get
.
Next, note that by the product rule,
.
Inserting another and rearranging, we get
.
Finally, combining (1) and (2) above results in the desired transformation:
.
If we adopt the notation to describe the transformed wave function, the equations can be written in a clearer form. For instance, can be rewritten as
,
which can be rewritten in the form of the original Schrödinger equation,
The original wave function can be recovered as .
Relation to the interaction picture
Unitary transformations can be seen as a generalization of the interaction (Dirac) picture. In the latter approach, a Hamiltonian is broken into a time-independent part and a time-dependent part,
.
In this case, the Schrödinger equation becomes
, with .
The correspondence to a unitary transformation can be shown by choosing . As a result,
Using the notation from above, our transformed Hamiltonian becomes
First note that since is a function of , the two must commute. Then
,
which takes care of the first term in the transformation in , i.e. . Next use the chain rule to calculate
which cancels with the other . Evidently we are left with , yielding as shown above.
When applying a general unitary transformation, however, it is not necessary that be broken into parts, or even that be a function of any part of the Hamiltonian.
Examples
Rotating frame
Consider an atom with two states, ground and excited . The atom has a Hamiltonian , where is the frequency of light associated with the ground-to-excited transition. Now suppose we illuminate the atom with a drive at frequency which couples the two states, and that the time-dependent driven Hamiltonian is
for some complex drive strength . Because of the competing frequency scales (, , and ), it is difficult to anticipate the effect of the drive (see driven harmonic motion).
Without a drive, the phase of would oscillate relative to . In the Bloch sphere representation of a two-state system, this corresponds to rotation around the z-axis. Conceptually, we can remove this component of the dynamics by entering a rotating frame of reference defined by the unitary transformation . Under this transformation, the Hamiltonian becomes
.
If the driving frequency is equal to the g-e transition's frequency, , resonance will occur and then the equation above reduces to
.
From this it is apparent, even without getting into details, that the dynamics will involve an oscillation between the ground and excited states at frequency .
As another limiting case, suppose the drive is far off-resonant, . We can figure out the dynamics in that case without solving the Schrödinger equation directly. Suppose the system starts in the ground state . Initially, the Hamiltonian will populate some component of . A small time later, however, it will populate roughly the same amount of but with completely different phase. Thus the effect of an off-resonant drive will tend to cancel itself out. This can also be expressed by saying that an off-resonant drive is rapidly rotating in the frame of the atom.
These concepts are illustrated in the table below, where the sphere represents the Bloch sphere, the arrow represents the state of the atom, and the hand represents the drive.
Displaced frame
The example above could also have been analyzed in the interaction picture. The following example, however, is more difficult to analyze without the general formulation of unitary transformations. Consider two harmonic oscillators, between which we would like to engineer a beam splitter interaction,
.
This was achieved experimentally with two microwave cavity resonators serving as and . Below, we sketch the analysis of a simplified version of this experiment.
In addition to the microwave cavities, the experiment also involved a transmon qubit, , coupled to both modes. The qubit is driven simultaneously at two frequencies, and , for which .
In addition, there are many fourth-order terms coupling the modes, but most of them can be neglected. In this experiment, two such terms which will become important are
.
(H.c. is shorthand for the Hermitian conjugate.) We can apply a displacement transformation, , to mode . For carefully chosen amplitudes, this transformation will cancel while also displacing the ladder operator, . This leaves us with
.
Expanding this expression and dropping the rapidly rotating terms, we are left with the desired Hamiltonian,
.
Relation to the Baker–Campbell–Hausdorff formula
It is common for the operators involved in unitary transformations to be written as exponentials of operators, , as seen above. Further, the operators in the exponentials commonly obey the relation , so that the transform of an operator is,. By now introducing the iterator commutator,
we can use a special result of the Baker-Campbell-Hausdorff formula to write this transformation compactly as,
or, in long form for completeness,
| Physical sciences | Quantum mechanics | Physics |
63319438 | https://en.wikipedia.org/wiki/COVID-19%20vaccine | COVID-19 vaccine | A COVID19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID19).
Knowledge about the structure and function of previous coronaviruses causing diseases like severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) accelerated the development of various vaccine platforms in early 2020. In 2020, the first COVID19 vaccines were developed and made available to the public through emergency authorizations and conditional approvals. However, immunity from the vaccines was found to wane over time, requiring people to get booster doses of the vaccine to maintain protection against COVID19.
The COVID19 vaccines are widely credited for their role in reducing the spread of COVID19 and reducing the severity and death caused by COVID19. Many countries implemented phased distribution plans that prioritized those at highest risk of complications, such as the elderly, and those at high risk of exposure and transmission, such as healthcare workers.
Common side effects of COVID19 vaccines include soreness, redness, rash, inflammation at the injection site, fatigue, headache, myalgia (muscle pain), and arthralgia (joint pain), which resolve without medical treatment within a few days. COVID19 vaccination is safe for people who are pregnant or are breastfeeding.
, 13.72billion doses of COVID19 vaccines have been administered worldwide, based on official reports from national public health agencies. By December 2020, more than 10 billion vaccine doses had been preordered by countries, with about half of the doses purchased by high-income countries comprising 14% of the world's population.
Despite the extremely rapid development of effective mRNA and viral vector vaccines, worldwide vaccine equity has not been achieved. The development and use of whole inactivated virus (WIV) and protein-based vaccines have also been recommended, especially for use in developing countries.
The 2023 Nobel Prize in Physiology or Medicine was awarded to Katalin Karikó and Drew Weissman for the development of effective mRNA vaccines against COVID-19.
Background
Prior to COVID19, a vaccine for an infectious disease had never been produced in less than several yearsand no vaccine existed for preventing a coronavirus infection in humans. However, vaccines have been produced against several animal diseases caused by coronaviruses, including (as of 2003) infectious bronchitis virus in birds, canine coronavirus, and feline coronavirus. Previous projects to develop vaccines for viruses in the family Coronaviridae that affect humans have been aimed at severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Vaccines against SARS and MERS have been tested in non-human animals.
According to studies published in 2005 and 2006, the identification and development of novel vaccines and medicines to treat SARS was a priority for governments and public health agencies around the world at that time. There is no cure or protective vaccine proven to be safe and effective against SARS in humans. There is also no proven vaccine against MERS. When MERS became prevalent, it was believed that existing SARS research might provide a useful template for developing vaccines and therapeutics against a MERS-CoV infection. As of March 2020, there was one (DNA-based) MERS vaccine that completed PhaseI clinical trials in humans, and three others in progress, all being viral-vectored vaccines: two adenoviral-vectored (ChAdOx1-MERS, BVRS-GamVac) and one MVA-vectored (MVA-MERS-S).
Vaccines that use an inactive or weakened virus that has been grown in eggs typically take more than a decade to develop. In contrast, mRNA is a molecule that can be made quickly, and research on mRNA to fight diseases was begun decades before the COVID19 pandemic by scientists such as Drew Weissman and Katalin Karikó, who tested on mice. Moderna began human testing of an mRNA vaccine in 2015. Viral vector vaccines were also developed for the COVID19 pandemic after the technology was previously cleared for Ebola.
As multiple COVID19 vaccines have been authorized or licensed for use, real-world vaccine effectiveness (RWE) is being assessed using case control and observational studies. A study is investigating the long-lasting protection against SARS-CoV-2 provided by the mRNA vaccines.
Vaccine technologies
The initial focus of SARS-CoV-2 vaccines was on preventing symptomatic, often severe, illness. Most of the first COVID19 vaccines were two-dose vaccines, with the exception single-dose vaccines Convidecia and the Janssen COVID‑19 vaccine, and vaccines with three-dose schedules, Razi Cov Pars and Soberana.
As of July 2021, at least nine different technology platforms were under research and development to create an effective vaccine against COVID19. Most of the platforms of vaccine candidates in clinical trials are focused on the coronavirus spike protein (S protein) and its variants as the primary antigen of COVID19 infection, since the S protein triggers strong B-cell and T-cell immune responses. However, other coronavirus proteins are also being investigated for vaccine development, like the nucleocapsid, because they also induce a robust T-cell response and their genes are more conserved and recombine less frequently (compared to Spike). Future generations of COVID19 vaccines that may target more conserved genomic regions will also act as insurance against the manifestation of catastrophic scenarios concerning the future evolutionary path of SARS-CoV-2, or any similar coronavirus epidemic/pandemic.
Platforms developed in 2020 involved nucleic acid technologies (nucleoside-modified messenger RNA and DNA), non-replicating viral vectors, peptides, recombinant proteins, live attenuated viruses, and inactivated viruses.
Many vaccine technologies being developed for COVID19 are not like influenza vaccines but rather use "next-generation" strategies for precise targeting of COVID19 infection mechanisms. Several of the synthetic vaccines use a 2P mutation to lock the spike protein into its prefusion configuration, stimulating an adaptive immune response to the virus before it attaches to a human cell. Vaccine platforms in development may improve flexibility for antigen manipulation and effectiveness for targeting mechanisms of COVID19 infection in susceptible population subgroups, such as healthcare workers, the elderly, children, pregnant women, and people with weakened immune systems.
mRNA vaccines
Several COVID19 vaccines, such as the Pfizer–BioNTech and Moderna vaccines, use RNA to stimulate an immune response. When introduced into human tissue, the vaccine contains either self-replicating RNA or messenger RNA (mRNA), which both cause cells to express the SARS-CoV-2 spike protein. This teaches the body how to identify and destroy the corresponding pathogen. RNA vaccines often use nucleoside-modified messenger RNA. The delivery of mRNA is achieved by a coformulation of the molecule into lipid nanoparticles, which protect the RNA strands and help their absorption into the cells.
RNA vaccines are the first COVID19 vaccines to be authorized in the United Kingdom, the United States, and the European Union. Authorized vaccines of this type include the Pfizer–BioNTech and Moderna vaccines. The CVnCoV RNA vaccine from CureVac failed in clinical trials.
Severe allergic reactions are rare. In December 2020, 1,893,360 first doses of Pfizer–BioNTech COVID19 vaccine administration resulted in 175 cases of severe allergic reactions, of which 21 were anaphylaxis. For 4,041,396 Moderna COVID19 vaccine dose administrations in December 2020 and January 2021, only ten cases of anaphylaxis were reported. Lipid nanoparticles (LNPs) were most likely responsible for the allergic reactions.
Adenovirus vector vaccines
These vaccines are examples of non-replicating viral vector vaccines using an adenovirus shell containing DNA that encodes a SARS‑CoV‑2 protein. The viral vector-based vaccines against COVID19 are non-replicating, meaning that they do not make new virus particles but rather produce only the antigen that elicits a systemic immune response.
Authorized vaccines of this type include the Oxford–AstraZeneca COVID‑19 vaccine, the Sputnik V COVID‑19 vaccine, Convidecia, and the Janssen COVID‑19 vaccine.
Convidecia and Janssen are both one-shot vaccines that offer less complicated logistics and can be stored under ordinary refrigeration for several months.
Sputnik V uses Ad26 for its first dose, which is the same as Janssen's only dose, and Ad5 for the second dose, which is the same as Convidecia's only dose.
In August 2021, the developers of Sputnik V proposed, in view of the Delta case surge, that Pfizer test the Ad26 component (termed its 'Light' version) as a booster shot.
Inactivated virus vaccines
Inactivated vaccines consist of virus particles that are grown in culture and then killed using a method such as heat or formaldehyde to lose disease-producing capacity while still stimulating an immune response.
Inactivated virus vaccines authorized in China include the Chinese CoronaVac and the Sinopharm BIBP and WIBP vaccines; there is also the Indian Covaxin, the Russian CoviVac, the Kazakh vaccine QazVac, and the Iranian COVIran Barekat. Vaccines in clinical trials include the Valneva COVID19 vaccine.
Subunit vaccines
Subunit vaccines present one or more antigens without introducing whole pathogen particles. The antigens involved are often protein subunits, but they can be any molecule fragment of the pathogen.
The authorized vaccines of this type include the peptide vaccine EpiVacCorona, ZF2001, MVC-COV1901, Corbevax, the Sanofi–GSK vaccine, and Soberana 02 (a conjugate vaccine). Bimervax (selvacovatein) was approved for use as a booster vaccine in the European Union in March 2023.
The V451 vaccine was in clinical trials that were terminated after it was found that the vaccine may potentially cause incorrect results for subsequent HIV testing.
Virus-like particle vaccines
The authorized vaccines of this type include the Novavax COVID‑19 vaccine.
Other types
Additional types of vaccines that are in clinical trials include multiple DNA plasmid vaccines, at least two lentivirus vector vaccines, a conjugate vaccine, and a vesicular stomatitis virus displaying the SARS‑CoV‑2 spike protein.
Scientists investigated whether existing vaccines for unrelated conditions could prime the immune system and lessen the severity of COVID19 infections. There is experimental evidence that the BCG vaccine for tuberculosis has non-specific effects on the immune system, but there is no evidence that this vaccine is effective against COVID19.
List of authorized vaccines
Delivery methods
Most coronavirus vaccines are administered by injection, with further vaccine delivery methods being studied for future coronavirus vaccines.
Intranasal
Intranasal vaccines target mucosal immunity in the nasal mucosa, which is a portal for viral entry into the body. These vaccines are designed to stimulate nasal immune factors, such as IgA. In addition to inhibiting the virus, nasal vaccines provide ease of administration because no needles (or needle phobia) are involved.
A variety of intranasal COVID19 vaccines are undergoing clinical trials. The first authorised intranasal vaccine was Razi Cov Pars in Iran at the end of October 2021. The first viral component of Sputnik V vaccine was authorised in Russia as Sputnik Nasal in April 2022. In September 2022, India and China approved two nasal COVID19 vaccines (iNCOVACC and Convidecia), which may (as boosters) also reduce transmission (potentially via sterilizing immunity). In December 2022, China approved a second intranasal vaccine as a booster, trade name Pneucolin.
Autologous
Aivita Biomedical is developing an experimental autologous dendritic cell COVID19 vaccine kit where the vaccine is prepared and incubated at the point-of-care using cells from the intended recipient. The vaccine is undergoing small phase I and phase II clinical studies.
Universal vaccine
A universal coronavirus vaccine would be effective against all coronaviruses and possibly other viruses. The concept was publicly endorsed by NIAID director Anthony Fauci, virologist Jeffery K. Taubenberger, and David M. Morens. In March 2022, the White House released the "National COVID19 Preparedness Plan", which recommended accelerating the development of a universal coronavirus vaccine.
One attempt at such a vaccine is being developed at the Walter Reed Army Institute of Research. It uses a spike ferritin-based nanoparticle (SpFN). This vaccine began a Phase I clinical trial in April 2022. Results of this trial were published in May 2024. Other universal vaccines that have entered clinical trial include OVX033 (France), PanCov (France), pEVAC-PS (UK), and VBI-2902 (Canada).
Another strategy is to attach vaccine fragments from multiple strains to a nanoparticle scaffold. One theory is that a broader range of strains can be vaccinated against by targeting the receptor-binding domain, rather than the whole spike protein.
Formulation
, eleven of the vaccine candidates in clinical development use adjuvants to enhance immunogenicity. An immunological adjuvant is a substance formulated with a vaccine to elevate the immune response to an antigen, such as the COVID19 virus or influenza virus. Specifically, an adjuvant may be used in formulating a COVID19 vaccine candidate to boost its immunogenicity and efficacy to reduce or prevent COVID19 infection in vaccinated individuals. Adjuvants used in COVID19 vaccine formulation may be particularly effective for technologies using the inactivated COVID19 virus and recombinant protein-based or vector-based vaccines. Aluminum salts, known as "alum", were the first adjuvant used for licensed vaccines and are the adjuvant of choice in some 80% of adjuvanted vaccines. The alum adjuvant initiates diverse molecular and cellular mechanisms to enhance immunogenicity, including the release of proinflammatory cytokines.
In June 2024, the US Food and Drug Administration (FDA) advised the manufacturers of the licensed and authorized COVID-19 vaccines that the COVID-19 vaccines (2024-2025 Formula) for use in the United States beginning in fall 2024 should be monovalent JN.1 vaccines.
Planning and development
Since January 2020, vaccine development has been expedited via unprecedented collaboration in the multinational pharmaceutical industry and between governments.
Multiple steps along the entire development path are evaluated, including:
the level of acceptable toxicity of the vaccine (its safety),
targeting vulnerable populations,
the need for vaccine efficacy breakthroughs,
the duration of vaccination protection,
special delivery systems (such as oral or nasal, rather than by injection),
dose regimen,
stability and storage characteristics,
emergency use authorization before formal licensing,
optimal manufacturing for scaling to billions of doses, and
dissemination of the licensed vaccine.
Challenges
There have been several unique challenges with COVID19 vaccine development.
Public health programs have been described as "[a] race to vaccinate individuals" with the early wave vaccines.
Timelines for conducting clinical researchnormally a sequential process requiring yearsare being compressed into safety, efficacy, and dosing trials running simultaneously over months, potentially compromising safety assurance. For example, Chinese vaccine developers and the Chinese Center for Disease Control and Prevention began their efforts in January 2020, and by March they were pursuing numerous candidates on short timelines.
The rapid development and urgency of producing a vaccine for the COVID19 pandemic were expected to increase the risks and failure rate of delivering a safe, effective vaccine. Additionally, research at universities is obstructed by physical distancing and the closing of laboratories.
Vaccines must progress through several phases of clinical trials to test for safety, immunogenicity, effectiveness, dose levels, and adverse effects of the candidate vaccine. Vaccine developers have to invest resources internationally to find enough participants for PhaseII–III clinical trials when the virus has proved to be a "moving target" of changing transmission rates across and within countries, forcing companies to compete for trial participants.
Clinical trial organizers may also encounter people unwilling to be vaccinated due to vaccine hesitancy or disbelief in the science of the vaccine technology and its ability to prevent infection. As new vaccines are developed during the COVID19 pandemic, licensure of COVID19 vaccine candidates requires submission of a full dossier of information on development and manufacturing quality.
Organizations
Internationally, the Access to COVID‑19 Tools Accelerator is a G20 and World Health Organization (WHO) initiative announced in April 2020. It is a cross-discipline support structure to enable partners to share resources and knowledge. It comprises four pillars, each managed by two to three collaborating partners: Vaccines (also called "COVAX"), Diagnostics, Therapeutics, and Health Systems Connector. The WHO's April 2020 "R&D Blueprint (for the) novel Coronavirus" documented a "large, international, multi-site, individually randomized controlled clinical trial" to allow "the concurrent evaluation of the benefits and risks of each promising candidate vaccine within 3–6 months of it being made available for the trial." The WHO vaccine coalition will prioritize which vaccines should go into PhaseII andIII clinical trials and determine harmonized PhaseIII protocols for all vaccines achieving the pivotal trial stage.
National governments have also been involved in vaccine development. Canada announced funding for 96 projects for the development and production of vaccines at Canadian companies and universities, with plans to establish a "vaccine bank" that could be used if another coronavirus outbreak occurs, support clinical trials, and develop manufacturing and supply chains for vaccines.
China provided low-rate loans to one vaccine developer through its central bank and "quickly made land available for the company" to build production plants. Three Chinese vaccine companies and research institutes are supported by the government for financing research, conducting clinical trials, and manufacturing.
The United Kingdom government formed a COVID19 vaccine task force in April 2020 to stimulate local efforts for accelerated development of a vaccine through collaborations between industries, universities, and government agencies. The UK's Vaccine Taskforce contributed to every phase of development, from research to manufacturing.
In the United States, the Biomedical Advanced Research and Development Authority (BARDA), a federal agency funding disease-fighting technology, announced investments to support American COVID19 vaccine development and the manufacturing of the most promising candidates. In May 2020, the government announced funding for a fast-track program called Operation Warp Speed. By March 2021, BARDA had funded an estimated $19.3 billion in COVID19 vaccine development.
Large pharmaceutical companies with experience in making vaccines at scale, including Johnson & Johnson, AstraZeneca, and GlaxoSmithKline (GSK), formed alliances with biotechnology companies, governments, and universities to accelerate progress toward effective vaccines.
Clinical research
Post-vaccination complications
History
In November 2021, the full nucleotide sequences of the AstraZeneca and Pfizer/BioNTech vaccines were released by the UK Medicines and Healthcare products Regulatory Agency in response to a freedom of information request.
Effectiveness
An analysis involving more than 20 million adults found that vaccinated people had a lower risk of long COVID compared to those who had not had a COVID-19 vaccine.
Duration of immunity
As of 2021, available evidence shows that fully vaccinated individuals and those previously infected with SARS-CoV-2 have a low risk of subsequent infection for at least six months. There is insufficient data to determine an antibody titer threshold that indicates when an individual is protected from infection. Multiple studies show that antibody titers are associated with protection at the population level, but individual protection titers remain unknown. For some populations, such as the elderly and the immunocompromised, protection levels may be reduced after both vaccination and infection. Available evidence indicates that the level of protection may not be the same for all variants of the virus.
As of December 2021, there are no FDA-authorized or approved tests that providers or the public can use to determine if a person is protected from infection reliably.
As of March 2022, elderly residents' protection against severe illness, hospitalization, and death in English care homes was high immediately after vaccination, but protection declined significantly in the months following vaccination. Protection among care home staff, who were younger, declined much more slowly. Regular boosters are recommended for older people, and boosters for care home residents every six months appear reasonable.
The US Centers for Disease Control and Prevention (CDC) recommends a fourth dose of the Pfizer mRNA vaccine for "certain immunocompromised individuals and people over the age of 50".
Immune evasion by variants
In contrast to other investigated prior variants, the SARS-CoV-2 Omicron variant and its BA.4/5 subvariants have evaded immunity induced by vaccines, which may lead to breakthrough infections despite recent vaccination. Nevertheless, vaccines are thought to provide protection against severe illness, hospitalizations, and deaths due to Omicron.
Vaccine adjustments
Effectiveness against transmission
As of 2022, fully vaccinated individuals with breakthrough infections with the SARS-CoV-2 delta (B.1.617.2) variant have a peak viral load similar to unvaccinated cases and can transmit infection in household settings.
Mix and match
According to studies, the combination of two different COVID19 vaccines, also called heterologous vaccination, cross-vaccination, or the mix-and-match method, provides protection equivalent to that of mRNA vaccines, including protection against the Delta variant. Individuals who receive the combination of two different vaccines produce strong immune responses, with side effects no worse than those caused by standard regimens.
Drug interactions
Methotrexate reduces the immune response to COVID-19 vaccines, making them less effective. Pausing methotrexate for two weeks following COVID-19 vaccination may result in improved immunity. Not taking the medicine for two weeks might result in a minor increase of inflammatory disease flares in some people.
Adverse events
For most people, the side effects, also called adverse effects, from COVID19 vaccines are mild and can be managed at home. The adverse effects of the COVID19 vaccination are similar to those of other vaccines, and severe adverse effects are rare. Adverse effects from the vaccine are higher than placebo, but placebo arms of vaccine trials still reported adverse effects that can be attributed to the nocebo effect.
All vaccines that are administered via intramuscular injection, including COVID19 vaccines, have side effects related to the mild trauma associated with the procedure and the introduction of a foreign substance into the body. These include soreness, redness, rash, and inflammation at the injection site. Other common side effects include fatigue, headache, myalgia (muscle pain), and arthralgia (joint pain), all of which generally resolve without medical treatment within a few days. Like any other vaccine, some people are allergic to one or more ingredients in COVID19 vaccines. Typical side effects are stronger and more common in younger people and in subsequent doses, and up to 20% of people report a disruptive level of side effects after the second dose of an mRNA vaccine. These side effects are less common or weaker in inactivated vaccines. COVID19 vaccination-related enlargement of lymph nodes happens in 11.6% of those who received one dose of the vaccine and in 16% of those who received two doses.
Experiments in mice show that intramuscular injections of lipid excipient nanoparticles (an inactive substance that serves as the vehicle or medium) cause particles to enter the blood plasma and many organs, with higher concentrations found in the liver and lower concentrations in the spleen, adrenal glands, and ovaries. The highest concentration of nanoparticles was found at the injection site itself.
COVID19 vaccination is safe for breastfeeding people. Temporary changes to the menstrual cycle in young women have been reported. However, these changes are "small compared with natural variation and quickly reverse." In one study, women who received both doses of a two-dose vaccine during the same menstrual cycle (an atypical situation) may see their next period begin a couple of days late. They have about twice the usual risk of a clinically significant delay (about 10% of these women, compared to about 4% of unvaccinated women). Cycle lengths return to normal after two menstrual cycles post-vaccination. Women who received doses in separate cycles had approximately the same natural variation in cycle lengths as unvaccinated women. Other temporary menstrual effects have been reported, such as heavier than normal menstrual bleeding after vaccination.
Serious adverse events associated COVID19 vaccines are generally rare but of high interest to the public. The official databases of reported adverse events include
the World Health Organization's VigiBase;
the United States Vaccine Adverse Events Reporting System (VAERS);
the United Kingdom's Yellow Card Scheme;
the European Medicines Agency's EudraVigilance system, which operates a regular transfer of data on suspected adverse drug reactions occurring in the EU to WHO's Uppsala Monitoring Centre.
Increased public awareness of these reporting systems and the extra reporting requirements under US FDA Emergency Use Authorization rules have increased reported adverse events. Serious side effects are an ongoing area of study, and resources have been allocated to try to better understand them. Research currently indicates that the rate and type of side effects are lower-risk than infection. For example, although vaccination may trigger some side effects, the effects experienced from an infection could be worse. Neurological side effects from getting COVID19 are hundreds of times more likely than from vaccination.
Documented rare serious effects include:
anaphylaxis, a severe type of allergic reaction. Anaphylaxis affects one person per 250,000 to 400,000 doses administered. According to a 2022 systematic review, the mortality rate of people with anaphylaxis following COVID‐19 vaccination was 0,5%.
blood clots (thrombosis). These vaccine-induced immune thrombocytopenia and thrombosis are associated with vaccines using an adenovirus system (Janssen and Oxford-AstraZeneca). These affect about one person per 100,000.
myocarditis and pericarditis, or inflammation of the heart. There is a rare risk of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the membrane covering the heart) after the mRNA COVID19 vaccines (Moderna or Pfizer-BioNTech). The risk of myocarditis after COVID19 vaccination is estimated to be 0.3 to 5 cases per 100,000 persons, with the highest risk in young males. In an Israeli nation-wide population-based study (in which the Pfizer-BioNTech vaccine was exclusively given), the incidence rate of myocarditis was 54 cases out of 2.5 million vaccine recipients, with an overall incidence rate of 2 cases per 100,000 persons, with the highest incidence seen in young males (aged 16 to 29) at 10 cases per 100,000 vaccine recipients. Of the cases of myocarditis seen, 76% were mild in severity, with one case of cardiogenic shock (heart failure) and one death (in a person with a preexisting heart condition) reported within the 83-day follow-up period. COVID19 vaccines may protect against myocarditis due to subsequent COVID19 infection. The risk of myocarditis and pericarditis is significantly higher (up to 11 times higher with respect to myocarditis) after COVID19 infection as compared to COVID19 vaccination, with the possible exception of younger men (less than 40 years old) who may have a higher risk of myocarditis after the second Moderna mRNA vaccine (an additional 97 cases of myocarditis per 1 million persons vaccinated). The mortality rate from myocarditis post-vaccination is extremely low. According to a 2022 study, of patients diagnosed with myocarditis (in both vaccination and COVID-19 cohort) 1.07% were hospitalized and 0.015% died.
thrombotic thrombocytopenia and other autoimmune diseases, which have been reported as adverse events after the COVID19 vaccine.
There are rare reports of subjective hearing changes, including tinnitus, after vaccination.
Society and culture
Distribution
Note about the table in this section: number and percentage of people who have received at least one dose of a COVID19 vaccine (unless noted otherwise). May include vaccination of non-citizens, which can push totals beyond 100% of the local population. The table is updated daily by a bot.
Access
Countries have extremely unequal access to the COVID19 vaccine. Vaccine equity has not been achieved or even approximated. The inequity has harmed both countries with poor access and countries with good access.
Nations pledged to buy doses of the COVID19 vaccines before the doses were available. Though high-income nations represent only 14% of the global population, as of 15 November 2020, they had contracted to buy 51% of all pre-sold doses. Some high-income nations bought more doses than would be necessary to vaccinate their entire populations.
In January 2021, WHO Director-General Tedros Adhanom Ghebreyesus warned of problems with equitable distribution: "More than 39 million doses of vaccine have now been administered in at least 49 higher-income countries. Just 25 doses have been given in one lowest-income country. Not 25 million; not 25 thousand; just 25."
In March 2021, it was revealed that the US attempted to convince Brazil not to purchase the Sputnik V COVID19 vaccine, fearing "Russian influence" in Latin America. Some nations involved in long-standing territorial disputes have reportedly had their access to vaccines blocked by competing nations; Palestine has accused Israel of blocking vaccine delivery to Gaza, while Taiwan has suggested that China has hampered its efforts to procure vaccine doses.
A single dose of the COVID19 vaccines by AstraZeneca would cost 47 Egyptian pounds (EGP), and the authorities are selling them for between 100 and 200 EGP. A report by the Carnegie Endowment for International Peace cited the poverty rate in Egypt as around 29.7 percent, which constitutes approximately 30.5 million people, and claimed that about 15 million Egyptians would be unable to gain access to the luxury of vaccination. A human rights lawyer, Khaled Ali, launched a lawsuit against the government, forcing them to provide vaccinations free of charge to all members of the public.
According to immunologist Anthony Fauci, mutant strains of the virus and limited vaccine distribution pose continuing risks, and he said, "we have to get the entire world vaccinated, not just our own country." Edward Bergmark and Arick Wierson are calling for a global vaccination effort and wrote that the wealthier nations' "me-first" mentality could ultimately backfire because the spread of the virus in poorer countries would lead to more variants, against which the vaccines could be less effective.
In March 2021, the United States, Britain, European Union member states, and some other members of the World Trade Organization (WTO) blocked a push by more than eighty developing countries to waive COVID19 vaccine patent rights in an effort to boost production of vaccines for poor nations. On 5 May 2021, the US government under President Joe Biden announced that it supports waiving intellectual property protections for COVID19 vaccines. The Members of the European Parliament have backed a motion demanding the temporary lifting of intellectual property rights for COVID19 vaccines.
In a meeting in April 2021, the World Health Organization's emergency committee addressed concerns of persistent inequity in global vaccine distribution. Although 9 percent of the world's population lives in the 29 poorest countries, these countries had received only 0.3% of all vaccines administered as of May 2021. In March 2021, Brazilian journalism agency Agência Pública reported that the country vaccinated about twice as many people who declare themselves white than black and noted that mortality from COVID19 is higher in the black population.
In May 2021, UNICEF made an urgent appeal to industrialized nations to pool their excess COVID19 vaccine capacity to make up for a 125-million-dose gap in the COVAX program. The program mostly relied on the Oxford–AstraZeneca COVID‑19 vaccine produced by the Serum Institute of India, which faced serious supply problems due to increased domestic vaccine needs in India from March to June 2021. Only a limited amount of vaccines can be distributed efficiently, and the shortfall of vaccines in South America and parts of Asia is due to a lack of expedient donations by richer nations. International aid organizations have pointed at Nepal, Sri Lanka, and the Maldives, as well as Argentina, Brazil, and some parts of the Caribbean, as problem areas where vaccines are in short supply. In mid-May 2021, UNICEF was also critical of the fact that most proposed donations of Moderna and Pfizer vaccines were not slated for delivery until the second half of 2021 or early in 2022.
In July 2021, the heads of the World Bank Group, the International Monetary Fund, the World Health Organization, and the World Trade Organization said in a joint statement: "As many countries are struggling with new variants and a third wave of COVID19 infections, accelerating access to vaccines becomes even more critical to ending the pandemic everywhere and achieving broad-based growth. We are deeply concerned about the limited vaccines, therapeutics, diagnostics, and support for deliveries available to developing countries." In July 2021, The BMJ reported that countries had thrown out over 250,000 vaccine doses as supply exceeded demand and strict laws prevented the sharing of vaccines. A survey by The New York Times found that over a million doses of vaccine had been thrown away in ten U.S. states because federal regulations prohibit recalling them, preventing their redistribution abroad. Furthermore, doses donated close to expiration often cannot be administered quickly enough by recipient countries and end up having to be discarded. To help overcome this problem, the Prime Minister of India, Narendra Modi, announced that they would make their digital vaccination management platform, CoWIN, open to the global community. He also announced that India would also release the source code for the contact tracing app Aarogya Setu for developers around the world. Around 142 countries, including Afghanistan, Bangladesh, Bhutan, the Maldives, Guyana, Antigua and Barbuda, St. Kitts and Nevis, and Zambia, expressed their interest in the application for COVID management.
Amnesty International and Oxfam International have criticized the support of vaccine monopolies by the governments of producing countries, noting that this is dramatically increasing the dose price by five times and often much more, creating an economic barrier to access for poor countries. Médecins Sans Frontières (Doctors without Borders) has also criticized vaccine monopolies and repeatedly called for their suspension, supporting the TRIPS waiver. The waiver was first proposed in October 2020 and has support from most countries, but was delayed by opposition from the EU (especially Germany; major EU countries such as France, Italy, and Spain support the exemption), the UK, Norway, and Switzerland, among others. MSF called for a Day of Action in September 2021 to put pressure on the WTO Minister's meeting in November, which was expected to discuss the TRIPS IP waiver.
In August 2021, to reduce unequal distribution between rich and poor countries, the WHO called for a moratorium on booster doses at least until the end of September. However, in August, the United States government announced plans to offer booster doses eight months after the initial course to the general population, starting with priority groups. Before the announcement, the WHO harshly criticized this type of decision, citing the lack of evidence for the need for boosters, except for patients with specific conditions. At this time, vaccine coverage of at least one dose was 58% in high-income countries and only 1.3% in low-income countries, and 1.14 million Americans had already received an unauthorized booster dose. US officials argued that waning efficacy against mild and moderate disease might indicate reduced protection against severe disease in the coming months. Israel, France, Germany, and the United Kingdom have also started planning boosters for specific groups. In September 2021, more than 140 former world leaders and Nobel laureates, including former President of France François Hollande, former Prime Minister of the United Kingdom Gordon Brown, former Prime Minister of New Zealand Helen Clark, and Professor Joseph Stiglitz, called on the candidates to be the next German chancellor to declare themselves in favor of waiving intellectual property rules for COVID19 vaccines and transferring vaccine technologies. In November 2021, nursing unions in 28 countries filed a formal appeal with the United Nations over the refusal of the UK, EU, Norway, Switzerland, and Singapore to temporarily waive patents for COVID19 vaccines.
During his first international trip, the President of Peru, Pedro Castillo, spoke at the seventy-sixth session of the United Nations General Assembly on 21 September 2021, proposing the creation of an international treaty signed by world leaders and pharmaceutical companies to guarantee universal vaccine access, arguing that "The battle against the pandemic has shown us the failure of the international community to cooperate under the principle of solidarity."
Optimizing the societal benefit of vaccination may benefit from a strategy that is tailored to the state of the pandemic, the demographics of a country, the age of the recipients, the availability of vaccines, and the individual risk for severe disease. In the UK, the interval between prime and booster doses was extended to vaccinate as many people as early as possible. Many countries are starting to give an additional booster shot to the immunosuppressed and the elderly, and research predicts an additional benefit of personalizing vaccine doses in the setting of limited vaccine availability when a wave of virus Variants of Concern hits a country.
Despite the extremely rapid development of effective mRNA and viral vector vaccines, vaccine equity has not been achieved. The World Health Organization called for 70 percent of the global population to be vaccinated by mid-2022, but as of March 2022, it was estimated that only one percent of the 10 billion doses given worldwide had been administered in low-income countries. An additional 6 billion vaccinations may be needed to fill vaccine access gaps, particularly in developing countries. Given the projected availability of newer vaccines, the development and use of whole inactivated virus (WIV) and protein-based vaccines are also recommended. Organizations such as the Developing Countries Vaccine Manufacturers Network could help to support the production of such vaccines in developing countries, with lower production costs and greater ease of deployment.
While vaccines substantially reduce the probability and severity of infection, it is still possible for fully vaccinated people to contract and spread COVID19. Public health agencies have recommended that vaccinated people continue using preventive measures (wear face masks, social distance, wash hands) to avoid infecting others, especially vulnerable people, particularly in areas with high community spread. Governments have indicated that such recommendations will be reduced as vaccination rates increase and community spread declines.
Economics
Vaccine inequity damages the global economy, disrupting the global supply chain. Most vaccines were reserved for wealthy countries; , some countries have more vaccines than are needed to fully vaccinate their populations. When people are under-vaccinated, needlessly die, experience disability, and live under lockdown restrictions, they cannot supply the same goods and services. This harms the economies of under-vaccinated and over-vaccinated countries alike. Since rich countries have larger economies, rich countries may lose more money to vaccine inequity than poor ones, though the poor ones will lose a higher percentage of GDP and experience longer-term effects. High-income countries would profit an estimated US$4.80 for every $1 spent on giving vaccines to lower-income countries.
The International Monetary Fund sees the vaccine divide between rich and poor nations as a serious obstacle to a global economic recovery. Vaccine inequity disproportionately affects refuge-providing states, as they tend to be poorer, and refugees and displaced people are economically more vulnerable even within those low-income states, so they have suffered more economically from vaccine inequity.
Liability
Several governments agreed to shield pharmaceutical companies like Pfizer and Moderna from negligence claims related to COVID19 vaccines (and treatments), as in previous pandemics, when governments also took on liability for such claims.
In the US, these liability shields took effect on 4 February 2020, when the US Secretary of Health and Human Services, Alex Azar, published a notice of declaration under the Public Readiness and Emergency Preparedness Act (PREP Act) for medical countermeasures against COVID19, covering "any vaccine, used to treat, diagnose, cure, prevent, or mitigate COVID19, or the transmission of SARS-CoV-2 or a virus mutating therefrom". The declaration precludes "liability claims alleging negligence by a manufacturer in creating a vaccine, or negligence by a health care provider in prescribing the wrong dose, absent willful misconduct." In other words, absent "willful misconduct", these companies cannot be sued for money damages for any injuries that occur between 2020 and 2024 from the administration of vaccines and treatments related to COVID19. The declaration is effective in the United States through 1October 2024.
In December 2020, the UK government granted Pfizer legal indemnity for its COVID19 vaccine.
In the European Union, the COVID19 vaccines were granted a conditional marketing authorization, which does not exempt manufacturers from civil and administrative liability claims. The EU conditional marketing authorizations were changed to standard authorizations in September 2022. While the purchasing contracts with vaccine manufacturers remain secret, they do not contain liability exemptions, even for side effects not known at the time of licensure.
The Bureau of Investigative Journalism, a nonprofit news organization, reported in an investigation that unnamed officials in some countries, such as Argentina and Brazil, said that Pfizer demanded guarantees against costs of legal cases due to adverse effects in the form of liability waivers and sovereign assets such as federal bank reserves, embassy buildings, or military bases, going beyond what was expected from other countries, such as the US. During the pandemic parliamentary inquiry in Brazil, Pfizer's representative said that its terms for Brazil are the same as for all other countries with which it has signed deals.
On 13 December 2022, the governor of Florida, Ron DeSantis, said that he would petition the state supreme court to convene a grand jury to investigate possible violations in respect to COVID19 vaccines, and declared that his government would be able to get "the data whether they [the companies] want to give it or not".
On 30 November 2023, the U.S. state of Texas sued Pfizer under section 17.47 of the Texas Deceptive Trade Practices Act, alleging that the company misled the public about its Covid-19 vaccine by hiding risks while making false claims about its effectiveness. On 17 June 2024, the U.S. state of Kansas similarly sued Pfizer under the Kansas Consumer Protection Act, making similar allegations.
Controversy
In June 2021, a report revealed that the UB-612 vaccine, developed by the US-based Covaxx, was a for-profit venture initiated by Blackwater founder Erik Prince. In a series of text messages to Paul Behrends, the close associate recruited for the Covaxx project, Prince described the profit-making possibilities of selling the COVID19 vaccines. Covaxx provided no data from the clinical trials on safety or efficacy it conducted in Taiwan. The responsibility of creating distribution networks was assigned to an Abu Dhabi-based entity, which was mentioned as "Windward Capital" on the Covaxx letterhead but was actually Windward Holdings. The firm's sole shareholder, who handled "professional, scientific and technical activities", was Erik Prince. In March 2021, Covaxx raised $1.35 billion in a private placement.
Misinformation and hesitancy
The United States Department of Defense (DoD) undertook a disinformation campaign in the Philippines, later expanded to Central Asia and the Middle East, which sought to discredit China, in particular its Sinovac vaccine, disseminating hashtags of #ChinaIsTheVirus and posts claiming that the Sinovac vaccine contained gelatin from pork and therefore was haram or forbidden for purposes of Islamic law.
| Biology and health sciences | Vaccines | Health |
72092111 | https://en.wikipedia.org/wiki/Box%20turtle | Box turtle | Box turtle is the common name for several species of turtle. It may refer to those of the genus Cuora or Pyxidea, which are the Asian box turtles, or more commonly to species of the genus Terrapene, the North American box turtles. They are largely characterized by having a shell shaped like a dome, which is hinged at the bottom, allowing the animal to close its shell tightly to escape predators. Furthermore, the two genera are very different in habitat, behavior and appearance, and are not even classified in the same family. Even though box turtles became very popular pets, their needs in captivity are complex and the capture of turtles can have serious detrimental effects on the wild population.
The box turtle commonly lives over twenty years, with verified cases of lifespans exceeding 40 to 50 years. There have been unverified cases of box turtles living for a hundred years and more.
Diet
Box turtles are omnivorous. Their eagle eyes and keen sense of smell help them find foods such as snails, insects, berries, fungi, slugs, worms, flowers, fish, frogs, salamanders, various rodents, snakes, birds, eggs, among other things. During their first five to six years of life they are primarily carnivorous. Adults tend to be mostly herbivores, but do not feed on leafy greens. Box turtles are known to feed on animals found dead on roadways, victims of being struck by a car or other rolling vehicle. Hatchlings and young turtles need more protein and prefer a carnivorous diet, to which, as they grow, they incorporate more and more plants.
Research
A recent study conducted by Davidson College revealed, among other things, that a box turtle can make sounds with its jaws that exceed 75 dB. This sound can be used to scare away predators and even also as some kind of mating call.
Mating
While it appears that most matings of Terrapene carolina occur in one-on-one encounters, there are occasions when two males will compete for access to the same female. These encounters, which almost never amount to mortal combat, consist of head-butting, shoving, and perhaps attempts to overturn the other. It is presumed that eventually one of the males exhausts himself and withdraws from the field while the other gains access to the female. Mating occurs during nesting season beginning in the late boreal spring and ceasing at the end of the summer months.
Preservation
Asian box turtles are in serious danger of extinction in their habitat because they are part of the food base of many Asian countries such as China, where they are captured for local food markets despite captive breeding farms. North American box turtles, on the other hand, are endangered by habitat destruction. The forests converted to farmland greatly reduced the number of turtles in many states. The remaining land is often fragmented with highways and urban projects, destroying the animals' habitat. In an attempt to cross man-made additions, turtles are often killed by cars, animals, and other hazards. They are also facing population decline from a necrotizing bacterial infection first found in this species April 2011.
Another serious treatment of these animals in North America is the capture and sale of hatchling box turtles from the wild. A 3-year study conducted in Texas indicated that more than 7000 box turtles were taken from the wild for commercial trade. A similar study in Louisiana found that over a 41-month period, about 30,000 box turtles were taken from the wild for resale. Once captured, the turtles are often kept in poor conditions, in which more than half die. Those that live long enough to be sold usually suffer from conditions such as malnutrition, dehydration, and infection.
Indiana and many other states created strict laws against the collection of hatchling turtles from the wild. In many states it is illegal to keep them without a special permit. Collecting wild-hatched box turtles can cause irreversible damage to populations, because these turtles have a low reproductive rate, as they take a long time to find a mate.
Most turtle and sea-turtle societies do not recommend the use of turtles as pets for young children despite their popularity as such. Box turtles are easily stressed if touched excessively and require more care than is generally thought. Box turtles can be easily injured by dogs and cats so special care must be taken to protect them from household pets and neighborhood animals. Box turtles require an enclosed outdoor location, consistent sun exposure and a varied diet. Without this, a turtle's growth can be stunted and its immune system weakened.
Finding box turtles in the wild and taking them as pets, even for a short period, can have detrimental effects. Box turtles want to stay within the area where they were hatched. If one is moved more than half a mile from its territory, it may not find its way back, but may spend years searching for it. This exposes the animal to danger and also disrupts the breeding cycle of which it would otherwise have been a part.
While box turtles are very popular as pets, it is important that they are preserved in the right matter. Keeping them in a more northern area where they can survive the best in ecological and physiological factor to not damage their way of living.
Taxonomy
North American box turtles
Family Emydidae
Genus Terrapene
Terrapene carolina
Eastern box turtle, Terrapene carolina carolina (Linnaeus, 1758)
Florida box turtle, Terrapene carolina bauri (Taylor, 1894)
Gulf Coast box turtle, Terrapene carolina major (Agassiz, 1857)
Three-toed box turtle, Terrapene carolina triunguis (Agassiz, 1857)
Mexican box turtle, Terrapene carolina mexicana (Gray, 1849)
Yucatán box turtle, Terrapene carolina yucatana (Boulenger, 1895)
Coahuilan box turtle, Terrapene coahuila (Schmidt & Owens, 1944)
Spotted box turtle, Terrapene nelsoni (Stejneger, 1925)
Terrapene ornata
Ornate box turtle, Terrapene ornata ornata (Agassiz, 1857)
Desert box turtle, Terrapene ornata luteola (Smith & Ramsey, 1952)
Asian box turtles
Family Geoemydidae
Genus Cuora
Amboina box turtle, Cuora amboinensis (Suckow, 1798)
Yellow-headed box turtle, Cuora aurocapitata (Luo & Zong, 1988)
Chinese box turtle, Cuora flavomarginata (Gray, 1863)
Indochinese box turtle, Cuora galbinifrons (Bourret, 1939)
McCord's box turtle, Cuora mccordi (Ernst, 1988)
Pan's box turtle, Cuora pani (Song, 1987)
Golden coin turtle, Cuora trifasciata (Bell, 1825)
Yunnan box turtle, Cuora yunnanensis (Boulenger, 1906)
Zhou's box turtle, Cuora zhoui (Zhao, 1990)
Genus Pyxidea
Keeled box turtle, Pyxidea mouhotii (Gray, 1862)
Pyxidea mouhotii mouhotii
Pyxidea mouhotii obsti
| Biology and health sciences | Reptiles | null |
66204363 | https://en.wikipedia.org/wiki/Climate%20change%20vulnerability | Climate change vulnerability | Climate change vulnerability is a concept that describes how strongly people or ecosystems are likely to be affected by climate change. Its formal definition is the "propensity or predisposition to be adversely affected" by climate change. It can apply to humans and also to natural systems (or ecosystems). Issues around the capacity to cope and adapt are also part of this concept. Vulnerability is a component of climate risk. It differs within communities and also across societies, regions, and countries. It can increase or decrease over time. Vulnerability is generally a bigger problem for people in low-income countries than for those in high-income countries.
Higher levels of vulnerability are found in areas with poverty, poor governance and conflict. Also, some livelihoods are more sensitive to the effects of climate change than others. Smallholder farmers, pastoralists, and fishing communities are livelihoods that may be especially vulnerable. Further drivers for vulnerability are unsustainable land and ocean use, inequity, marginalization, and historical and ongoing patterns of inequity and poor governance.
There are many different notions of what it means to be vulnerable. An important distinction is between biophysical and social vulnerability. Biophysical vulnerability is about the effects of climate hazards such as heat waves or tropical cyclones. Social vulnerability, on the other hand, is about the underlying political, institutional, economic and social factors within societies. These factors matter for how and why people are affected, and they put some people and places more at risk than others. People who are more vulnerable include for example people with low incomes, indigenous peoples, women, children, the elderly.
Tools for vulnerability assessment vary depending on the sector, the scale and the entity or system which is thought to vulnerable. For example, the Vulnerability Sourcebook is a guide for practical and scientific knowledge on vulnerability assessment. Climate vulnerability mapping helps to understand which areas are the most vulnerable. Mapping can also help to communicate climate vulnerability to stakeholders. It is useful to carry out vulnerability assessments in advance of preparing local climate adaptation plans or risk management plans. Global vulnerability assessments use spatial mapping with aggregated data for the regional or national level.
Definition
Climate change vulnerability is defined as the "propensity or predisposition to be adversely affected" by climate change. It can apply to humans but also to natural systems (ecosystems), and both are interdependent. Vulnerability is a component of climate risk. Vulnerability will be higher if the capacity to cope and adapt is low.
Climate vulnerability can include a wide variety of different meanings, situations, and contexts in climate change research. It has been a central concept in academic research and IPCC assessments since 2001.
The concept was defined in the Third IPCC report (2001) as "the degree to which a system is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes".
Early studies focused on biophysical vulnerability to climate change. In other words, the effects of physical climate hazards such as a heat wave or heavy rain events. This direction of research was shaped by earlier natural hazards research and it emphasised physical changes and energy flows in the landscape. It aims to quantify and measure the impacts of an event on the environment and on people. Since (biophysical) vulnerability is interpreted here as the negative outcome of climate change on people or places, it is also sometimes referred to as 'outcome vulnerability'.
An alternative framing focuses on social dimensions of vulnerability that set the context in which climate change happens. These dimensions include the political, institutional, economic and social structures that interact with the physical climate changes. For example, water privatization might affect the ability of people to respond to drought. This direction of research was shaped by human security research and they focus on the current context or 'starting point' for the social and biophysical processes. They are sometimes also referred to as 'contextual vulnerability' approaches. Research in this area focuses on analysing the factors that "put people and places at risk and reduce capacity to respond". See the section on 'Causes' below.
In the Fifth IPCC report, the social context was emphasized. It noted factors such as wealth and employment, access to technology and information, societal values and the role of institutions to resolve conflicts or develop relations among states as important. Vulnerability was defined as a characteristic of people or places independently of physical events. The report included two additional definitions, one of contextual vulnerability and one of outcome vulnerability.
Vulnerability and exposure
In the climate change context, exposure is defined as "the presence of people; livelihoods; species or ecosystems; environmental functions, services, and resources; infrastructure; or economic, social, or cultural assets in places and settings that could be adversely affected.".
In earlier definitions of vulnerability to climate change (in the Third IPCC report and Fourth IPCC report) vulnerability was defined as a function of exposure, sensitivity and adaptive capacity. This changed during the Fifth IPCC cycle. In this report, exposure was defined as one of the three interacting elements of climate risk, rather than as one of the external drivers of vulnerability. This change had two main implications. First, it means that vulnerability is understood as independent of exposure (and hazard) but is contextual. Second, it means that vulnerability assessment could focus on indicators for sensitivity and adaptive capacity to understand the current system weaknesses. For example, weaknesses such as the high ground slope of a farmland or marginalization of households in a community would make people or places sensitive to climate impacts. This makes it important to select the most hazard-relevant indicators for any vulnerability assessment. For example, to assess the vulnerability of traditional coastal fishing communities to sea surge, ‘distance of dwellings from sea’ and ‘elevation of dwellings from sea level’ would be hazard-relevant indicators.
Types
Climate change vulnerability has a wide variety of different meanings and uses of the term have varied and evolved over time. The main distinction is between biophysical and social (or socioeconomic) vulnerability:
Biophysical vulnerability is about the effects of physical climate hazards such as a heat wave or heavy rain events
Social vulnerability considers the many political, institutional, economic and social structures that form the context for climate change
Biophysical or (physical) vulnerability
Early studies focused on biophysical vulnerability to climate change. In other words, the effects of physical climate hazards such as a heat wave or heavy rain events. This direction of research was shaped by earlier natural hazards research and it emphasised physical changes and energy flows in the landscape. It aims to quantify and measure the impacts of an event on the environment and on people. It plays down the role of people themselves in managing these impacts. Since (biophysical) vulnerability is interpreted here as the negative outcome of climate change on people or places, it is also sometimes referred to as 'outcome vulnerability'.
Physical vulnerability tends to focus on outcomes of monetary loss and disruptions. It is also sometimes defined as the "degree of loss" on a scale of 0 (no loss) to 1 (total loss). In this framework, for example, physical vulnerability to surface water hazards in mountain areas has been widely studied.
Social (socioeconomic) vulnerability
Social vulnerability is a more people-centred, holistic perspective on how and why people are affected by climate change. Vulnerability of ecosystems and people to climate change is driven by certain unsustainable development patterns such as "unsustainable ocean and land use, inequity, marginalization, historical and ongoing patterns of inequity such as colonialism, and governance". Therefore, vulnerability is higher in some locations than in others. Certain aspects within a region increase vulnerability, for example poverty, governance challenges and violent conflict. Some types of livelihoods are regarded as particularly climate-sensitive, resulting in a higher level of climate change vulnerability. These include for example smallholder farmers, pastoralists and fishing communities.
At its basic level, a community that is economically vulnerable is one that is ill-prepared for the effects of climate change because it lacks the needed financial resources. Preparing a climate resilient society will require huge investments in infrastructure, city planning, engineering sustainable energy sources, and preparedness systems. From a global perspective, it is more likely that people living at or below poverty will be affected the most by climate change and are thus the most vulnerable, because they will have the least amount of resource dollars to invest in resiliency infrastructure. They will also have the least amount of resource dollars for cleanup efforts after more frequently occurring natural climate change related disasters.
Vulnerability for people of a certain gender or age can be caused by "systemic reproduction of historical legacies of inequality", for example as part of "(post)colonial, (post)apartheid, and poverty discrimination". Social vulnerability of people can be related to aspects that make people different from one another (gender, class, race, age, etc.), and also the situational variables (where they live, their health, who lives with them in the household, how much they earn).
Other categories
Geographic, or place-based vulnerability to climate change is an important dimension. The most geographically vulnerable locations to climate change are those that will be impacted by side effects of natural hazards, such as rising sea levels and by dramatic changes in ecosystem services, including access to food. Island nations are usually noted as more vulnerable but communities that rely heavily on a sustenance based lifestyle are also at greater risk.
Around the world, climate change affects rural communities that heavily depend on their agriculture and natural resources for their livelihood. Increased frequency and severity of climate events disproportionately affects women, rural, dryland, and island communities. This leads to more drastic changes in their lifestyles and forces them to adapt to this change. It is becoming more important for local and government agencies to create strategies to react to change and adapt infrastructure to meet the needs of those impacted. Various organizations work to create adaptation, mitigation, and resilience plans that will help rural and at risk communities around the world that depend on the earth's resources to survive.
Scale
It has been estimated in 2021 that "approximately 3.3 to 3.6 billion people live in contexts that are highly vulnerable to climate change".
The vulnerability of ecosystems and people to climate change is not the same everywhere: there are marked differences among and within regions (see regions that are particularly vulnerable below). Vulnerability can also increase or decrease over time.
People who are more vulnerable
People who are more vulnerable to the effects of climate change than others include for example people with low incomes, indigenous peoples, women, children, the elderly. For example, when looking at the effects of climate change on human health, a report published in The Lancet found that the greatest impact tends to fall on the most vulnerable people such as the poor, women, children, the elderly, people with pre-existing health concerns, other minorities and outdoor workers.
There can be "structural deficits related to social, economic, cultural, political, and institutional conditions" which would explain why some parts of the population are more impacted than others. This applies for example to climate-related risks to household water security for women in remote rural regions in Burkina Faso or the urban poor in sub-Saharan Africa.
The Impact of Climate Change on Health Outcomes
Varying Racial and Ethnic Groups
The extent to which climate change can negatively impact the health outcomes of populations may vary amongst different racial and ethnic groups across the globe. It is also important in this case to note that social positions can be denoted by race or ethnicity. Therefore, there can exist a variance in health outcomes as a result of differences in exposure and accessibility to healthcare to mitigate the health damages caused by climate change.
It is understood that increased exposure to high temperatures as a result of global warming can lead to acute heat-related illnesses such as heat stroke or can aggravate pre-existing conditions. In a study done in Los Angeles, California during a heat wave, it was found that African American populations were at greater risk of mortality. In fact, the mortality rate of African Americans during this 2006 heat wave was double that of the average population. Heat-related emergency department visits were also significantly increased for ethnic populations as there was a spike in emergency department visits found amongst Asian/Pacific Islander populations and African American populations.
Although some may attribute the discrepancy in mortality and hospitalization rates among ethnic groups to physiological differences between populations, not enough evidence has been provided to support this statement. Rather, studies show that these differences in health outcomes amongst different racial and ethnic groups are more likely to be the result of socioeconomic variance. Racial minorities are more likely to be socioeconomically disadvantaged and are therefore more likely to take on underpaid high-risk occupations, live in hazardous areas, and have difficulty finding the financial resources to maintain a healthy level of thermal comfort.
A study done in Phoenix, Arizona highlighted that more heat distress calls were made in neighborhoods consisting of primarily African American and low-income Hispanic populations. It is found that financially disadvantaged communities, often which are composed of ethnic minorities, have a propensity to be warmer neighborhoods despite the lack of access to means of thermal regulation.
The urban heat island effect emphasizes the fact that urban areas tend to be most impacted. During a heat wave in Oklahoma City, a study examined the urban island heat effect in varying communities. It was found that the hotter inner city region, one densely populated by minority residents, was severely inadequately equipped with air-conditioning. This inadequate access to resources that allow for thermal regulation in homes, coupled with overcrowded living spaces in low-income, minority communities can be a significant health hazard.
It is also important to discuss occupational hazards when elaborating upon the impact of climate change on the health outcomes of varying racial and ethnic groups. Extreme heat can be detrimental to outdoor workers. Several studies have revealed that the agricultural workforce has been negatively affected by the growing effects of climate change. The majority of agricultural workers are from Latin America, with also a significant population who are also composed of Asian and Caribbean migrants, and people of Native American and African American descent. In the same analysis done on the 2006 heat wave in California, it was found that there was a significantly increased rate of hospitalization for cardiac-related illnesses amongst crop workers of Hispanic backgrounds as a result of occupational hazards. To mitigate this concern, more relevant occupational health and safety training programs should be set in place and working conditions should be more carefully monitored.
Language barriers may also play a role in the difference of health outcomes amongst varying ethnic groups as a result of climate change. Reduced access to English media and important public health statements as a result of linguistic barriers. This may also lead to a reduction of adaptive behavior and can put some individuals in danger of experiencing heat-related illnesses or exacerbating existing conditions.
Older Adults (65+ years)
Introduction
As global temperatures rise, extreme weather events become more frequent, and air quality worsens due to climate change, older adults (aged 65 and above) face increased risks of heat-related illnesses, chronic disease, and infectious diseases. Both physiological vulnerabilities and sociological factors compound the risk of negative health outcomes that older adults face from climate change.
Reducing vulnerability
Vulnerability can be reduced through climate change adaptation measures. For this reason, vulnerability is often framed in dialogue with climate change adaptation. Furthermore, measures that reduce poverty, gender inequality, bad governance and violent conflict would also reduce vulnerability. And finally, vulnerability would be reduced for everyone if decisive action on climate change was taken (climate change mitigation) so that the effects of climate change are less severe.
Climate change adaptation
Climate resilience
Climate justice
Equity is another essential component of vulnerability and is closely tied to issues of environmental justice and climate justice. As the most vulnerable communities are likely to be the most heavily impacted, a climate justice movement is coalescing in response. There are many aspects of climate justice that relate to vulnerability and resiliency. The frameworks are similar to other types of justice movements and include contractarianism which attempts to allocate the most benefits for the poor, utilitarianism which seeks to find the most benefits for the most people, egalitarianism which attempts to reduce inequality, and libertarianism which emphasizes a fair share of burden but also individual freedoms.
Examples of climate justices approach can be seen by the work done by the United States government on both federal and local levels. On a federal level, The Environmental Protection Agency works toward the goals of Executive Order 12898, Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations. E.O 12898 states the goals of implementing federal environmental justice initiatives that work toward aiding minority and low-income communities that suffer from disproportionate environmental or human health impacts. To alleviate environmental and health challenges within many American communities the U.S Environmental Protection Agency has implemented projects region by region to ensure the development of environmental justice. These developments include but are not limited to population vulnerability, green space development locally as well as federally, and the reevaluation of environmentally disproportionate health burdens.
Climate Vulnerable Forum
Measurement tools
Vulnerability assessment is important because it provides information that can be used to develop management actions in response to climate change. Climate change vulnerability assessments and tools are available at all scales. Macro-scale vulnerability assessment often uses indices. Modelling and participatory approaches are also in use. Global vulnerability assessments are based on spatial mapping using aggregated data for the regional or national level.
Assessments are also done at sub-national and sectoral level, and also increasingly for cities on an urban district or neighbourhood scale. Vulnerability assessment is also done for local communities to evaluate where and how communities and livelihoods are vulnerable to climate change. Studies can vary widely in scope and scale— for example the World Bank and Ministry of Economy of Fiji commissioned a report for the whole country in 2017-18 while the Rochester, New York commissioned a much more local report for the city in 2018. Or, for example, NOAA Fisheries commissioned Climate Vulnerability assessments for marine fishers in the United States. In some cases vulnerability assessment is done in advance of preparing local climate adaptation plans or risk management plans.
Indicators and indices
Global indices for climate change vulnerability include the ND-GAIN Country Index, which measures national climate vulnerability globally, INFORM Risk Index and the WorldRiskIndex, which include social vulnerability indices. Indicator approaches are also used at national and sub-national levels. They use a composite index of many individual quantifiable indicators. To generate the index value or 'score', most often a simple average is calculated across a set of standardized values. However, sometimes weighting is done according what are thought to be the most important determinants of vulnerability.
Climate vulnerability tracking starts identifying the relevant information, preferably open access, produced by state or international bodies at the scale of interest. Then a further effort to make the vulnerability information freely accessible to all development actors is required. Vulnerability tracking has many applications. It constitutes an indicator for the monitoring and evaluation of programs and projects for resilience and adaptation to climate change. Vulnerability tracking is also a decision making tool in regional and national adaptation policies.
Vulnerability curves
Climate vulnerability curves are a method of assessing physical vulnerability on various sectors such as agriculture, infrastructure, health, and ecosystems. They show a relationship between different levels of climate-related hazards (like extreme temperatures, sea-level rise, or intense precipitation) and the effects, or damages.
Tools for vulnerability assessment
Similarly as for climate risk assessment, tools for vulnerability assessment vary depending on the sector, the scale at which the study is being carried out, and the entity or system which is thought to vulnerable. Modelling and other participatory tools include WEAP for understanding water resource vulnerabilities and assessing adaptation options. The Vulnerability Sourcebook is a guide for practical and scientific knowledge on vulnerability assessment. Climate vulnerability mapping is also used to understand which areas are the most geographically vulnerable. A systematic review published in 2019 found 84 studies focused on the use of mapping to communicate and do analysis of climate vulnerability.
By region and country
All regions of the world are vulnerable to climate change but to a different degree. With high confidence, researchers concluded in 2001 that developing countries would tend to be more vulnerable to climate change than developed countries. Based on development trends in 2001, scientists have found that few developing countries would have the capacity to efficiently adapt to climate change. This was partly due to their low adaptive capacity and the high costs of adaptation in proportion to their GDP.
The Arctic is extremely vulnerable to climate change. It was predicted in 2007 that there would be major ecological, sociological, and economic impacts in the region. Among those being disproportionately impacted by issues regarding climate change have been the Indigenous peoples of the Arctic, such as the Inuit, Yupik, and Saami, who are particularly vulnerable. Traditional livelihoods, including hunting, fishing, and reindeer herding, are threatened by changes in ice conditions, wildlife migration patterns, and habitat availability. Additionally, thawing permafrost can damage infrastructure and contaminate water sources, posing health and safety risks to communities.
Small island Developing States are particularly vulnerable to climate change. Partly this was attributed to their low adaptive capacity and the high costs of adaptation in proportion to their GDP. Climate change leads to more frequent and intense extreme weather events such as hurricanes, typhoons, and cyclones. Small islands are especially susceptible to these events, which can cause widespread destruction, loss of life, and economic setbacks.
In comparison, the climate vulnerability of Europe is lower than in developing countries. This was attributed to Europe's high GNP, stable growth, stable population, and well-developed political, institutional, and technological support systems.
| Physical sciences | Climate change | Earth science |
74872973 | https://en.wikipedia.org/wiki/Injury | Injury | Injury is physiological damage to the living tissue of any organism, whether in humans, in other animals, or in plants.
Injuries can be caused in many ways, including mechanically with penetration by sharp objects such as teeth or with blunt objects, by heat or cold, or by venoms and biotoxins. Injury prompts an inflammatory response in many taxa of animals; this prompts wound healing. In both plants and animals, substances are often released to help to occlude the wound, limiting loss of fluids and the entry of pathogens such as bacteria. Many organisms secrete antimicrobial chemicals which limit wound infection; in addition, animals have a variety of immune responses for the same purpose. Both plants and animals have regrowth mechanisms which may result in complete or partial healing over the injury. Cells too can repair damage to a certain degree.
Taxonomic range
Animals
Injury in animals is sometimes defined as mechanical damage to anatomical structure, but it has a wider connotation of physical damage with any cause, including drowning, burns, and poisoning. Such damage may result from attempted predation, territorial fights, falls, and abiotic factors.
Injury prompts an inflammatory response in animals of many different phyla; this prompts coagulation of the blood or body fluid, followed by wound healing, which may be rapid, as in the cnidaria. Arthropods are able to repair injuries to the cuticle that forms their exoskeleton to some extent.
Animals in several phyla, including annelids, arthropods, cnidaria, molluscs, nematodes, and vertebrates are able to produce antimicrobial peptides to fight off infection following an injury.
Humans
Injury in humans has been studied extensively for its importance in medicine. Much of medical practice, including emergency medicine and pain management, is dedicated to the treatment of injuries. The World Health Organization has developed a classification of injuries in humans by categories including mechanism, objects/substances producing injury, place of occurrence, activity when injured and the role of human intent. In addition to physical harm, injuries can cause psychological harm, including post-traumatic stress disorder.
Plants
In plants, injuries result from the eating of plant parts by herbivorous animals including insects and mammals, from damage to tissues by plant pathogens such as bacteria and fungi, which may gain entry after herbivore damage or in other ways, and from abiotic factors such as heat, freezing, flooding, lightning, and pollutants such as ozone. Plants respond to injury by signalling that damage has occurred, by secreting materials to seal off the damaged area, by producing antimicrobial chemicals, and in woody plants by regrowing over wounds.
Cell injury
Cell injury is a variety of changes of stress that a cell suffers due to external as well as internal environmental changes. Amongst other causes, this can be due to physical, chemical, infectious, biological, nutritional or immunological factors. Cell damage can be reversible or irreversible. Depending on the extent of injury, the cellular response may be adaptive and where possible, homeostasis is restored. Cell death occurs when the severity of the injury exceeds the cell's ability to repair itself. Cell death is relative to both the length of exposure to a harmful stimulus and the severity of the damage caused.
| Biology and health sciences | Illness and injury | null |
61243379 | https://en.wikipedia.org/wiki/Synthetic%20biopolymer | Synthetic biopolymer | Synthetic biopolymers are human-made copies of biopolymers obtained by abiotic chemical routes. Synthetic biopolymer of different chemical nature have been obtained, including polysaccharides, glycoproteins, peptides and proteins, polyhydroxoalkanoates, polyisoprenes.
Synthesis of biopolymer
The high molecular weight of biopolymers make their synthesis inherently laborious. Further challenges can arise from specific spatial arrangement adopted by the natural biopolymer, which may be vital for its properties/activity but not easily reproducible in the synthetic copy. Despite this, chemical approaches to obtain biopolymer are highly desirable to overcome issues arising from low abundance of the target biopolymer in Nature, the need for cumbersome isolation processes or high batch-to-batch variability or inhomogeneity of the naturally-sourced species.
Examples of synthetic biopolymers obtained by chemical routes
cis-1,4-polyisoprene (synthetic analogue of rubber) and trans-1,4-polyisoprene (synthetic analogue of gutta percha) are obtained by coordination polymerisation using suitable Ziegler-Natta catalysts.
Polyhydroxoalkanoates such as poly(3-hydroxobutyrate), poly(hydroxovaleric acid) etc. obtained by polycondensation and polyaddition. Low-molecular weight polylactide and other polyglycolides can also be obtained by chemical synthesis.
Oligonucleotides and polynucleotides (DNA or RNA) can be obtain by chemical synthesis through a variety of established approaches.
A variety of proteins have been obtained by chemical synthesis. A successful approach relies on native chemical ligation, which achieves the synthesis of proteins by linking shorter unprotected peptides. This strategy allowed to obtain, amongst many others, proteins such as insulin-like growth factor 1, the precursor of Aequorea green fluorescent protein and the influenza A virus M2 membrane protein.
Examples of biopolymers obtained by chemoenzymatic routes
Polyhydroxoalkanoates and polyesters obtained by enzyme-assisted esterification using lipases.
Heparin, heparan sulfate and other glycosaminoglycans and plant glycans.
Polysaccharides such as cellulose, amylose, chitin and derivatives
Natural and non-natural polynucleotides can be successfully obtained by enzyme-assisted synthesis using ligase- or polymerase-based approaches and template-assisted polymerisation.
Human-made biopolymers obtained through approaches that involve genetic engineering or recombinant DNA technology are different from synthetic biopolymers and should be referred to as artificial biopolymer (e.g., artificial protein, artificial polynucleotide, etc.).
Applications of synthetic biopolymers
As their natural analogues, synthetic biopolymers find applications in numerous fields, including materials for commodities, drug delivery, tissue engineering, therapeutic and diagnostic applications.
| Technology | Biotechnology | null |
61262925 | https://en.wikipedia.org/wiki/Electric%20eel | Electric eel | The electric eels are a genus, Electrophorus, of neotropical freshwater fish from South America in the family Gymnotidae. They are known for their ability to stun their prey by generating electricity, delivering shocks at up to 860 volts. Their electrical capabilities were first studied in 1775, contributing to the invention of the electric battery in 1800.
Despite their name, electric eels are not closely related to the true eels (Anguilliformes) but are members of the electroreceptive knifefish order Gymnotiformes. This order is more closely related to catfish. In 2019, electric eels were split into three species: for more than two centuries before that, the genus was believed to be monotypic, containing only Electrophorus electricus.
They are nocturnal, obligate air-breathing animals, with poor vision complemented by electrolocation; they mainly eat fish. Electric eels grow for as long as they live, adding more vertebrae to their spinal column. Males are larger than females. Some captive specimens have lived for over 20 years.
Evolution
Taxonomy
When the species now defined as Electrophorus electricus was described by Carl Linnaeus in 1766, based on early field research by Europeans in South America and specimens sent back to Europe for study, he used the name Gymnotus electricus, placing it in the same genus as Gymnotus carapo (the banded knifefish). He noted that the fish is from the rivers of Surinam, that it causes painful shocks, and that it had small pits around the head.
In 1864, Theodore Gill moved the electric eel to its own genus, Electrophorus.
The name is from the Greek ( 'amber, a substance able to hold static electricity'), and ( 'I carry'), giving the meaning 'electricity bearer'. In 1872, Gill decided that the electric eel was sufficiently distinct to have its own family, Electrophoridae. In 1998, Albert and Campos-da-Paz lumped the Electrophorus genus with the family Gymnotidae, alongside Gymnotus, as did Ferraris and colleagues in 2017.
In 2019, C. David de Santana and colleagues divided E. electricus into three species based on DNA divergence, ecology and habitat, anatomy and physiology, and electrical ability. The three species are E. electricus (now in a narrower sense than before), and the two new species E. voltai and E. varii.
Phylogeny
Electric eels form a clade of strongly electric fishes within the order Gymnotiformes, the South American knifefishes. Electric eels are thus not closely related to the true eels (Anguilliformes). The lineage of the Electrophorus genus is estimated to have split from its sister taxon Gymnotus sometime in the Cretaceous. Most knifefishes are weakly electric, capable of active electrolocation but not of delivering shocks. Their relationships, as shown in the cladogram, were analysed by sequencing their mitochondrial DNA in 2019. Actively electrolocating fish are marked with a small yellow lightning flash . Fish able to deliver electric shocks are marked with a red lightning flash .
Species
There are three described species in the genus, not differing significantly in body shape or coloration:
Electrophorus electricus This, the type species, has a U-shaped head, with a flattened skull and cleithrum.
Electrophorus voltai This species is the strongest bioelectricity generator in nature, capable of generating 860 V. Like E. electricus, this species has a flattened skull and cleithrum but the head is more egg-shaped.
Electrophorus varii Compared to the other two species, this one has a thicker skull and cleithrum but the head shape is more variable.
E. varii appears to have diverged from the other species around 7.1 mya during the late Miocene, while E. electricus and E. voltai may have split around 3.6 mya during the Pliocene.
Ecology
The three species have largely non-overlapping distributions in the northern part of South America. E. electricus is northern, confined to the Guiana Shield, while E. voltai is southern, ranging from the Brazilian shield northwards; both species live in upland waters. E. varii is central, largely in the lowlands. The lowland region of E. varii is a variable environment, with habitats ranging from streams through grassland and ravines to ponds, and large changes in water level between the wet and dry seasons. All live on muddy river bottoms and sometimes swamps, favouring areas in deep shade. They can tolerate water low in oxygen as they swim to the surface to breathe air.
Electric eels are mostly nocturnal. E. voltai mainly eats fish, in particular the armoured catfish Megalechis thoracata. A specimen of E. voltai had a caecilian (a legless amphibian), Typhlonectes compressicauda, in its stomach; it is possible that this means that the species is resistant to the caecilian's toxic skin secretions. E. voltai sometimes hunts in packs; and have been observed targeting a shoal of tetras, then herding them and launching joint strikes on the closely packed fish. The other species, E. varii, is also a fish predator; it preys especially on Callichthyidae (armoured catfishes) and Cichlidae (cichlids).
Biology
General biology
Electric eels have long, stout bodies, being somewhat cylindrical at the front but more flattened towards the tail end. E. electricus can reach in length, and in weight. The mouth is at the front of the snout, and opens upwards. They have smooth, thick, brown-to-black skin with a yellow or red underbelly and no scales. The pectoral fins each possess eight tiny radial bones at the tip.
They have over 100 precaudal vertebrae (excluding the tail), whereas other gymnotids have up to 51 of these; there can be as many as 300 vertebrae in total.
There is no clear boundary between the tail fin and the anal fin, which extends much of the length of the body on the underside and has over 400 bony rays. Electric eels rely on the wave-like movements of their elongated anal fin to propel themselves through the water.
Electric eels get most of their oxygen by breathing air using buccal pumping. This enables them to live in habitats with widely varying oxygen levels including streams, swamps, and pools. Uniquely among the gymnotids, the buccal cavity is lined with a frilled mucosa which has a rich blood supply, enabling gas exchange between the air and the blood. About every two minutes, the fish takes in air through the mouth, holds it in the buccal cavity, and expels it through the opercular openings at the sides of the head. Unlike in other air-breathing fish, the tiny gills of electric eels do not ventilate when taking in air. The majority of carbon dioxide produced is expelled through the skin. These fish can survive on land for some hours if their skin is wet enough.
Electric eels have small eyes and poor vision. They are capable of hearing via a Weberian apparatus, which consists of tiny bones connecting the inner ear to the swim bladder. All of the vital organs are packed in near the front of the animal, taking up only 20% of space and sequestered from the electric organs.
Electrophysiology
Electric eels can locate their prey using electroreceptors derived from the lateral line organ in the head. The lateral line itself is mechanosensory, enabling them to sense water movements created by animals nearby. The lateral line canals are beneath the skin, but their position is visible as lines of pits on the head. Electric eels use their high frequency-sensitive tuberous receptors, distributed in patches over the body, for hunting other knifefish.
Electric eels have three pairs of electric organs, arranged longitudinally: the main organ, Hunter's organ, and Sachs' organ. These organs give electric eels the ability to generate two types of electric organ discharges: low voltage and high voltage. The organs are made of electrocytes, modified from muscle cells. Like muscle cells, the electric eel's electrocytes contain the proteins actin and desmin, but where muscle cell proteins form a dense structure of parallel fibrils, in electrocytes they form a loose network. Five different forms of desmin occur in electrocytes, compared to two or three in muscle, but its function in electrocytes remained unknown as of 2017.
Potassium channel proteins involved in electric organ discharge, including KCNA1, KCNH6, and KCNJ12, are distributed differently among the three electric organs: most such proteins are most abundant in the main organ and least abundant in Sachs's organ, but KCNH6 is most abundant in Sachs's organ. The main organ and Hunter's organ are rich in the protein calmodulin, involved in controlling calcium ion levels. Calmodulin and calcium help to regulate the voltage-gated sodium channels that create the electrical discharge. These organs are also rich in sodium potassium ATPase, an ion pump used to create a potential difference across cell membranes.
The maximum discharge from the main organ is at least 600 volts, making electric eels the most powerful of all electric fishes. Freshwater fishes like the electric eel require a high voltage to give a strong shock because freshwater has high resistance; powerful marine electric fishes like the torpedo ray give a shock at much lower voltage but a far higher current. The electric eel produces its strong discharge extremely rapidly, at a rate of as much as 500 Hertz, meaning that each shock lasts only about two milliseconds. To generate a high voltage, an electric eel stacks some 6,000 electrocytes in series (longitudinally) in its main organ; the organ contains some 35 such stacks in parallel, on each side of the body. The ability to produce high-voltage, high-frequency pulses in addition enables the electric eel to electrolocate rapidly moving prey. The total electric current delivered during each pulse can reach about 1 ampere.
It remains unclear why electric eels have three electric organs but basically produce two types of discharge, to electrolocate or to stun. In 2021, Jun Xu and colleagues stated that Hunter's organ produces a third type of discharge at a middle voltage of 38.5 to 56.5 volts. Their measurements indicate that this is produced just once, for less than 2 milliseconds, after the low-voltage discharge of Sachs's organ and before the high-voltage discharge of the main organ. They believed that this is insufficient to stimulate a response from the prey, so they suggested it may have the function of co-ordination within the electric eel's body, perhaps by balancing the electrical charge, but state that more research is needed.
When an electric eel identifies prey, its brain sends a nerve signal to the electric organ; the nerve cells involved release the neurotransmitter chemical acetylcholine to trigger an electric organ discharge. This opens ion channels, allowing sodium to flow into the electrocytes, reversing the polarity momentarily. The discharge is terminated by an outflow of potassium ions through a separate set of ion channels. By causing a sudden difference in electric potential, it generates an electric current in a manner similar to a battery, in which cells are stacked to produce a desired total voltage output. It has been suggested that Sachs' organ is used for electrolocation; its discharge is of nearly 10 volts at a frequency of around 25 Hz. The main organ, supported by Hunter's organ in some way, is used to stun prey or to deter predators; it can emit signals at rates of several hundred hertz. Electric eels can concentrate the discharge to stun prey more effectively by curling up and making contact with the prey at two points along the body. It has also been suggested that electric eels can control their prey's nervous systems and muscles via electrical pulses, keeping prey from escaping, or forcing it to move so they can locate it, but this has been disputed. In self-defence, electric eels have been observed to leap from the water to deliver electric shocks to animals that might pose a threat. The shocks from leaping electric eels are powerful enough to drive away animals as large as horses.
Life cycle
Electric eels reproduce during the dry season, from September to December. During this time, male-female pairs are seen in small pools left behind after water levels drop. The male makes a nest using his saliva and the female deposits around 1,200 eggs for fertilisation. Spawn hatch seven days later and mothers keep depositing eggs periodically throughout the breeding season, making them fractional spawners. When they reach , the hatched larvae consume any leftover eggs, and after they reach they begin to eat other foods. Electric eels are sexually dimorphic, males becoming reproductively active at in length and growing larger than females; females start to reproduce at a body length of around . The adults provide prolonged parental care lasting four months. E. electricus and E. voltai, the two upland species which live in fast-flowing rivers, appear to make less use of parental care. The male provides protection for both the young and the nest. Captive specimens have sometimes lived for over 20 years.
As the fish grow, they continually add more vertebrae to their spinal column. The main organ is the first electric organ to develop, followed by Sachs' organ and then Hunter's organ. All the electric organs are differentiated by the time the body reaches a length of . Electric eels are able to produce electrical discharges when they are as small as .
Interactions with humans
Early research
The first written mention of the electric eel or ('the one that numbs' in Tupi) is in records by the Jesuit priest Fernão Cardim in 1583.
The naturalists Bertrand Bajon, a French military surgeon in French Guiana, and the Jesuit in the River Plate basin, conducted early experiments on the numbing discharges of electric eels in the 1760s. In 1775, the "torpedo" (the electric ray) was studied by John Walsh; both fish were dissected by the surgeon and anatomist John Hunter. Hunter informed the Royal Society that "Gymnotus Electricus[...] appears very much like an eel[...] but it has none of the specific properties of that fish." He observed that there were "two pair of these [electric] organs, a larger [the main organ] and a smaller [Hunter's organ]; one being placed on each side", and that they occupied "perhaps[...] more than one-third of the whole animal [by volume]". He described the structure of the organs (stacks of electrocytes) as "extremely simple and regular, consisting of two parts; viz. flat partitions or septa, and cross divisions between them." He measured the electrocytes as thick in the main organ, and thick in Hunter's organ.
Also in 1775, the American physician and politician Hugh Williamson, who had studied with Hunter, presented a paper "Experiments and observations on the Gymnotus Electricus, or electric eel" at the Royal Society. He reported a series of experiments, such as "7. In order to discover whether the eel killed those fish by an emission of the same [electrical] fluid with which he affected my hand when I had touched him, I put my hand into the water, at some distance from the eel; another cat-fish was thrown into the water; the eel swam up to it ... [and] gave it a shock, by which it instantly turned up its belly, and continued motionless; at that very instant I felt such a sensation in the joints of my fingers as in experiment 4." and "12. Instead of putting my hand into the water, at a distance from the eel, as in the last experiment, I touched its tail, so as not to offend it, while my assistant touched its head more roughly; we both received a severe shock."
The studies by Williamson, Walsh, and Hunter appear to have influenced the thinking of Luigi Galvani and Alessandro Volta. Galvani founded electrophysiology, with research into how electricity makes a frog's leg twitch; Volta began electrochemistry, with his invention of the electric battery.
In 1800, the explorer Alexander von Humboldt joined a group of indigenous people who went fishing with horses, some thirty of which they chased into the water. The pounding of the horses' hooves, he noted, drove the fish, up to long out of the mud and prompted them to attack, rising out of the water and using their electricity to shock the horses. He saw two horses stunned by the shocks and then drowned. The electric eels, having given many shocks, "now require long rest and plenty of nourishment to replace the loss of galvanic power they have suffered", "swam timidly to the bank of the pond", and were easily caught using small harpoons on ropes. Humboldt recorded that the people did not eat the electric organs, and that they feared the fish so much that they would not fish for them in the usual way.
In 1839, the chemist Michael Faraday extensively tested the electrical properties of an electric eel imported from Surinam. For a span of four months, he measured the electrical impulses produced by the animal by pressing shaped copper paddles and saddles against the specimen. Through this method, he determined and quantified the direction and magnitude of electric current, and proved that the animal's impulses were electrical by observing sparks and deflections on a galvanometer. He observed the electric eel increasing the shock by coiling about its prey, the prey fish "representing a diameter" across the coil. He likened the quantity of electric charge released by the fish to "the electricity of a Leyden battery of fifteen jars, containing of glass coated on both sides, charged to its highest degree".
The German zoologist Carl Sachs was sent to Latin America by the physiologist Emil du Bois-Reymond, to study the electric eel; he took with him a galvanometer and electrodes to measure the fish's electric organ discharge, and used rubber gloves to enable him to catch the fish without being shocked, to the surprise of the local people. He published his research on the fish, including his discovery of what is now called Sachs' organ, in 1877.
Artificial electrocytes
The large quantity of electrocytes available in the electric eel enabled biologists to study the voltage-gated sodium channel in molecular detail. The channel is an important mechanism, as it serves to trigger muscle contraction in many species, but it is hard to study in muscle as it is found in extremely small amounts. In 2008, Jian Xu and David Lavan designed artificial cells that would be able to replicate the electrical behaviour of electric eel electrocytes. The artificial electrocytes would use a calculated selection of conductors at nanoscopic scale. Such cells would use ion transport as electrocytes do, with a greater output power density, and converting energy more efficiently. They suggest that such artificial electrocytes could be developed as a power source for medical implants such as retinal prostheses and other microscopic devices. They comment that the work "has mapped out changes in the system level design of the electrocyte" that could increase both energy density and energy conversion efficiency. In 2009, they made synthetic protocells which can provide about a twentieth of the energy density of a lead–acid battery, and an energy conversion efficiency of 10%.
In 2016, Hao Sun and colleagues described a family of electric eel-mimicking devices that serve as high output voltage electrochemical capacitors. These are fabricated as flexible fibres that can be woven into textiles. Sun and colleagues suggest that the storage devices could serve as power sources for products such as electric watches or light-emitting diodes.
| Biology and health sciences | Fishes | null |
64767216 | https://en.wikipedia.org/wiki/Bird%20wing | Bird wing | Bird wings are a paired forelimb in birds. The wings give the birds the ability to fly, creating lift.
Terrestrial flightless birds have reduced wings or none at all (for example, moa). In aquatic flightless birds (penguins), wings can serve as flippers.
Anatomy
Like most other tetrapods, the forelimb of birds consists of the shoulder (with the humerus), the forearm (with the ulna and the radius), and the hand.
The hand of birds is substantially transformed: some of its bones have been reduced, and some others have merged with each other. Three bones of the metacarpus and part of the carpal bones merge into a carpometacarpus. The bones of three fingers are attached to it. The frontmost one bears an alula—a group of feathers that act like the slats of an airplane. Usually, this finger has one phalanx bone, the next has two, and the back has one (but some birds have one more phalanx on the first two fingers—the claw).
Finger identity problem
The bones of three fingers are preserved in the bird wing. The question of which fingers they are has been discussed for about 150 years, and an extensive literature is devoted to it. The anatomical, paleontological, and molecular data suggests that these are fingers 1–3, but embryological data suggests that these are actually fingers 2–4. Several hypotheses have been proposed to explain this discrepancy. Most likely, in birds, finger buds 2–4 began to follow the genetic program for the development of fingers 1–3.
Wing shape
The shape of the wing is important in determining the flight capabilities of a bird. Different shapes correspond to different trade-offs between advantages such as speed, low energy use, and maneuverability.
Two important parameters are the aspect ratio and wing loading. Aspect ratio is the ratio of wingspan to the mean of its chord (or the square of the wingspan divided by wing area). Wing loading is the ratio of weight to wing area.
Most kinds of bird wings can be grouped into four types, with some falling between two of these types. These types of wings are elliptical wings, high-speed wings, high aspect ratio wings and soaring wings with slots.
Elliptical wings
Elliptical wings are rounded and short. This type of wing allows for tight maneuvering in confined spaces such as dense vegetation. Elliptical wings are common in forest raptors (such as Accipiter hawks), and many passerines, particularly non-migratory ones (migratory species have longer wings). They are also common in species that use a rapid takeoff to evade predators, such as pheasants and partridges.
High speed wings
High-speed wings are short, pointed wings that when combined with a heavy wing loading and rapid wingbeats provide an energetically expensive, but high-speed flight. This type of wing is present in fast-flying birds such as ducks. Birds that use their wings to "fly" underwater such as the auks also have small and elongated wings.
The peregrine falcon has the highest recorded dive speed of 242 mph (389 km/h). Peregrine falcons have relatively large wings but they partially close their wings during dives. The fastest straight, powered flight is the spine-tailed swift at 105 mph (170 km/h).
High aspect ratio wings
High aspect ratio (elongated) wings confer high flight efficiency for flights of long duration. When combined with a low wing loading, they are used for slow flight. This may take the form of almost hovering (as used by kestrels, terns and nightjars) or in soaring and gliding flight, particularly the dynamic soaring used by seabirds, which takes advantage of wind speed variation at different altitudes (wind shear) above ocean waves to provide lift. Low-speed flight is also important for birds that plunge-dive for fish.
Soaring wings with deep slots
These wings are favored by larger species of inland birds, such as eagles, vultures, pelicans, and storks. The slots at the end of the wings, between the primaries, reduce the induced drag and wingtip vortices by "capturing" the energy in air flowing from the lower to upper wing surface at the tips, whilst the shorter size of the wings aids in takeoff (high aspect ratio wings require a long taxi to get airborne).
| Biology and health sciences | External anatomy and regions of the body | Biology |
63413093 | https://en.wikipedia.org/wiki/Asteriornis | Asteriornis | Asteriornis ("Asteria's bird") is an extinct genus of bird from the Late Cretaceous of Belgium which is known from a single species, Asteriornis maastrichtensis. It was closely related to birds of the extant superorder Galloanserae such as chickens and ducks. Members of the genus were small, long-legged birds (~) that lived near the coastline and co-existed with more "primitive" types of birds such as Ichthyornis. Asteriornis is one of the oldest-known birds irrefutably belonging to the group Neornithes, which encompasses all modern birds. It possesses characteristics of both galliformes (chicken-like birds) and anseriformes (duck-like birds), indicating its position as a close relative of the last common ancestor for both groups.
Asteriornis may shed light on why Neornithes were the only dinosaurs to survive the Cretaceous–Paleogene extinction event. Its coexistence with non-neornithean birds such as Ichthyornis implies that competition was not a primary factor for the extinction of non-neornitheans, which resembled modern birds in most respects but died out with other non-avian dinosaurs. Small size, a terrestrial lifestyle, and a generalist diet have all been inferred as ecological advantages possessed by early neornithes, allowing them to survive and diversify in the wake of the extinction. Asteriornis fulfills these qualities, suggesting that such suspicions were justified. Asteriornis is also evidence against a different hypothesis stating that modern birds originated from southern continents. This was supported by biogeographic ancestral reconstructions using phylogenies and the discovery of Vegavis (a possible neornithean from Antarctica), but Asteriornis's presence in Europe suggests that modern birds may have been widespread in northern continents in their early evolution.
Discovery and naming
Asteriornis is based on specimen NHMM 2013 008, held in the Maastricht Natural History Museum (Dutch: Natuurhistorisch Museum Maastricht), which consists of an almost complete skull and fragments of leg bones and a radius. It was retrieved from four blocks of sediment found at the CBR-Romontbos quarry near Eben-Emael in the Maastricht Formation of Belgium, and was first unearthed in 2000, by amateur paleontologist Maarten van Dinther, who donated it to the museum. This geological formation is the namesake of the Maastrichtian stage, which was the last stage of the Cretaceous period and the Mesozoic era. It is dated to around 66.8 to 66.7 million years old, less than a million years before the arrival of the asteroid that caused the Cretaceous–Paleogene extinction event, killed off all non-avian dinosaurs (and many other animals), and began the Cenozoic era.
The genus name, Asteriornis, was constructed from ornis, the Greek word for bird, and from Asteria, a Greek goddess who was associated with falling stars, and about whom there is a famous myth in which she transforms herself into a quail. The Asteri part of genus name thus alludes to the Chicxulub impactor (a "falling star"), and also alludes to quails which are members of the galloanserans. The species name A. maastrichtensis is named after the Maastricht Formation. The researchers who discovered and described the fossil gave Asteriornis the nickname "Wonderchicken", which was picked up by various news outlets.
Description
The beak was slightly downcurved and lightweight. Unlike galloanserans, the beak did not have any specialized connections to the rest of the skull, nor a hooked tip. Instead its front tip was slightly rounded. The skull was narrowest over the orbits (eye sockets), where the frontal bones were incised by a V-shaped part of the nasal bones. The bones forming the jaw joint were very galloanseran-like. The quadrate bone (the cranium's contribution to the jaw joint) connected to the skull roof via two pronounced knobs, which were adjacent to a third smaller knob, the tuberculum subcapitulare. The mandible (lower jaw) connected to the quadrate with a pair of sockets, and the rear end of the lower jaw had a large hooked rearward-facing retroarticular process as well as a smaller inward-facing medial process. All of these characteristics are considered unique to (or at least most common in) galloanserans.
In some respects the skull seems more similar to galliform birds such as chickens and pheasants. These include unfused snout bones and nasal bones which fork in front of the eyes. In other respects it resembles anseriform birds such as ducks and geese. Such features include the hooked retroarticular process of the jaw and a postorbital process (the portion of bone forming the rear edge of the eye socket) which curves forward at its lower extent. These demonstrate a principle of evolution that animals close to the common ancestor of two groups share some similarities with each group.
The radius fragment flattens and widens towards the wrist, where it possesses a large hooked bump. Leg bones are elongated and slender, similar in proportions and structure to modern ground-living birds. The femur has well-developed muscle ridges and a large, angular medial condyle. The tibiotarsus is widest towards the knee, while the tarsometatarsus is thinner and covered with ridges.
Classification
A phylogenetic analysis placed Asteriornis near the base of Galloanserae, an expansive superorder containing birds such as chickens, ducks, pheasants, and other types of fowl and gamebirds. The precise placement varied based on whether the analysis used parsimony or Bayesian protocol. Parsimony placed it as the sister taxon to Galloanserae, meaning that it was a distant relative of the last common ancestor of chickens and ducks. Bayesian protocol instead placed it within Galloanserae, specifically as the sister taxon to Galliformes. This means that it was more closely related to chickens than to ducks, but also that was not a direct ancestor of modern chicken-like birds.
Classifying Asteriornis as a relative of chickens and ducks means that it is unequivocally a neornithean. This is important because Neornithes originated at the last common ancestor of all living birds, and corresponds to the term "bird" as it refers to modern-day animals. Pre-neornithean birds such as Ichthyornis, enantiornitheans, or Archaeopteryx generally resemble modern birds but retain primitive features such as teeth or wing claws. Neornithean fossils are extremely rare from the Mesozoic age, and are generally fragmentary or poorly described. The oldest known neognath, specifically a stem-anseriform, is the presbyornithid Teviornis from the Nemegt Formation of Mongolia around . Vegavis from the Late Cretaceous (~66.5 Ma) of Antarctica was originally described as a relative of ducks and geese, but the classification of vegaviids is controversial and some paleontologists do not consider it a proper neornithean, or at least not an anseriform or a galloanserine. Asteriornis is based on diagnostic and well-preserved skull material and its status is less unstable, so it can be considered among the oldest known undisputed fossil of a modern-style neornithean bird.
At least one study in 2021 has recovered Asteriornis as a paleognath, albeit "with limited support". Subsequent studies still support Asterornis as a neornithean closely related to or within Galloanserae based on morphometric and phylogenetic analyses. A 2024 cladistic analysis placed Asteriornis within the crown-group Galloanserae, specifically as a stem-galliform, though reexaminations of its mandible suggested that it lacked a key galloanserine feature.
| Biology and health sciences | Prehistoric birds | Animals |
54977531 | https://en.wikipedia.org/wiki/Shringasaurus | Shringasaurus | Shringasaurus (meaning "horned lizard", from Sanskrit शृङ्ग (śṛṅga), "horn", and Ancient Greek (sauros), "lizard") is an extinct genus of archosauromorph reptile from the Middle Triassic (Anisian) of India. It is known from the type and only known species, S. indicus. Shringasaurus is known from the Denwa Formation in the state of Madhya Pradesh. Shringasaurus was an allokotosaur, a group of unusual herbivorous reptiles from the Triassic, and is most closely related to the smaller and better known Azendohsaurus in the family Azendohsauridae. Like some ceratopsid dinosaurs, Shringasaurus had two large horns over its eyes that faced up and forwards from its skull. Shringasaurus also bears convergent physical similarities to sauropodomorph dinosaurs, such as its long neck, its shoulders and forelimbs, and the shape of its teeth. Shringasaurus possibly occupied a similar ecological niche as a large browsing herbivore before such dinosaurs had evolved.
Description
Shringasaurus was a large-bodied quadruped, with an estimated body length of . It closely resembles the related Azendohsaurus, with its small, boxy head on a long neck and a large, barrel-shaped body with deep shoulders and ribs, sprawled to semi-sprawled limbs and a short tail. Aside from being notably larger than Azendohsaurus, Shringasaurus is most recognisable for its long curving brow horns, as well as for having a proportionately shorter and thicker neck than other azendohsaurids and much taller neural spines in the neck and over the shoulders.
Skull
The skull of Shringasaurus is not completely known, but what's preserved indicates that the skull was small and boxy, with a short, deep snout with rounded jaw tips and bony nostrils fused into a single, confluent opening at the front of the snout. This is broadly similar to the completely known skull of Azendohsaurus, but the lower jaw of Shringasaurus has a more conspicuous taper towards the tip compared to the deep, down-turned dentary of the Azendohsaurus.
The horns of Shringasaurus closely resemble those seen in ceratopsid dinosaurs, despite azendohsaurids and ceratopsids being totally unrelated to each other. The horns are attached to the frontal bones on the roof of the skull over the eyes, and sit across almost the entire breadth of the skull. They are pointed up and curve forwards from the skull, with slight variation in size and orientation existing among large individuals. Smaller and younger individuals had smaller, more gracile horns, indicating that the horns did not fully develop until the animals were mature. Intriguingly, at least one small specimen lacks horns entirely, whereas another similarly small specimen has small but well developed horns. It is suggested then that Shringasaurus was sexually dimorphic, and that possibly the females lacked horns.
The horns themselves have a rough, grooved texture that implies they were covered with a keratinous sheath of horn in life, also like ceratopsid horns, and so would have likely been longer than the bony cores indicate. The bones of the skull beneath the horns are unusually thick, and in the larger individuals the bones of roof of the skull (the nasal, prefrontal, frontal and postfrontal) are fused together on each side.
The teeth of Shringasaurus are low and leaf-shaped (lanceolate) with large denticles on either side, similar in shape to those of Azendohsaurus but lacking the prominent expansion above the root, like the teeth of Pamelaria. Because the skull and jaws are incompletely known, the total tooth count of Shringasaurus is unknown, but like Azendohsaurus it had four teeth in each premaxilla. Shringasaurus also had numerous palatal teeth (though known only from the vomer thus far), and like Azendohsaurus they are uniquely as well developed as the marginal teeth along the edge of the jaw. Like them, they were leaf-shaped and serrated, but in Shringasaurus the palatal teeth are even more lanceolate than the marginal rows. Such palatal teeth are unusual, as most other herbivorous reptiles with them have much simpler, domed palatal teeth, and palatal teeth identical to those of the jaw margins are otherwise only found in the related allokotosaurs Azendohsaurus and Teraterpeton.
Skeleton
The vertebral column is well known in Shringasaurus, including the whole cervical series, various dorsal vertebrae, both sacral vertebrae and some caudal vertebrae. Like other azendohsaurids, the first-through-middle cervical vertebrae are characteristically elongated, giving Shringasaurus a long, raised neck, although it is proportionately shorter than in Azendohsaurus and Pamelaria. The neck is also much taller than in other azendohsaurids, with tall, prominent neural spines. This trend continues into the dorsals of the back, which although are not as long as the cervicals have neural spines twice the height of their centra. The 2nd–5th cervicals of Shringasaurus sport prominent epipophyses, structures for supporting neck musculature. The first twelve dorsals are also marked by various well-defined laminae that bound deep fossae (depressions in the bone), similar to those found on the vertebrae of sauropods. Like Azendohsaurus, Shringasaurus has two sacral vertebrae with well-developed ribs that articulate with the ilia.
The shoulder and forelimb are broadly similar to those of Azendohsaurus, with a tall scapula that is concave along the front with an expanded tip, and an interclavicle with a long paddle-like process on the back and a short forward-pointing process (an unusual feature for archosauromorphs but also found in Azendohsaurus). The coracoid articulates with the scapula to form a glenoid (shoulder socket) that faces out to the sides and back. The humerus is likewise similar, with broad ends and a narrow midshaft, and a very well-developed deltopectoral crest half as long as the whole bone, indicating powerful forelimbs. The ulna, however, can be distinguished by a lower olecranon process below the elbow than in Azendohsaurus.
The hips and hind limbs are very similar to those of Azendohsaurus. The ilium has a prominent, semi-circular process at the front while the rear process is longer and thinner, and the acetabulum (hip socket) is also solid, unlike the perforated hip socket of dinosaurs. The femur is robust and slightly s-shaped, held out to the sides in a sprawl, with a robust tibia and a fibula only half as wide in the lower leg. The foot is typical for early archosauromorphs, including Azendohsaurus.
Discovery and naming
Shringasaurus is known from a single bone bed of fossils in the upper Denwa Formation, India. The formation is part of the Satpura Gondwana Basin, located in the Hoshangabad district in the state of Madhya Pradesh. The precise age of the Denwa Formation is not known, but vertebrate biostratigraphy has been used to narrow it down to a range in the early Middle Triassic with conflicting opinions on an early or late Anisian age. The upper Denwa Formation is characteristically dominated by red mudstones with ribbon-shaped sandstone sheets encased within them. The bonebed itself was preserved in a crevasse splay deposit composed of cross-bedded, dipped sandstone with irregular boundaries that breached along the south edge of an ancient filled river channel. This flooding event was unlikely to be an isolated event, as the size of the crevasse splay suggests multiple phases of flooding that cumulatively buried the remains of the herd.
The Shringasaurus bone bed consists of mostly disarticulated bones (although one partial skeleton was found in articulation) scattered within a 5 m X 5 m () area of red mudstone with fine, sandy laminations. The bonebed is monodominant, only containing fossils of Shringasaurus, and preserves eight individuals based on the minimum number of unique right femora, left humeri, skull roofs and horns discovered. The specimens also represent a variety of different ontogenetic stages of growth with a wide range of body sizes, from juveniles to adults. Of these individuals, only one or two lacked horns, and it's suggested that the bone bed was taphonomically biased towards the heavier, solidly built skulls of horned individuals while being transported and preserved.
However, the retention of bones rapidly lost in transport (such as ribs and limb bones), as well as minimal abrasion to many of the bones, indicates they were not transported a great distance after death. Although the bones were later disarticulated after transportation (apart from a single series of six dorsal vertebrae and ribs), they remained in closely associated clusters. They also show little weathering, indicating that most of the bones only remained exposed on the surface for perhaps only 1–3 years, with only a few exposed for longer (3–15 years). The articulated vertebrae, found lowest in the bonebed, was likely buried immediately, while the remaining bones higher in the bonebed were buried by subsequent floods. Similarly, the bones show now signs of trampling or marks from scavenging and plant growth, indicative of their short exposure before burial.
The fossils were excavated and prepared by Professor Saswati Bandyopadhyay, Dhurjati Sengupta and Shiladri Das of the Indian Statistical Institute, Kolkata, where the fossils are also stored. It was then described and named in August 2017 by Sarandee Sengupta and Bandyopadhyay, as well as by Martín D. Ezcurra of the Bernardino Rivadavia Natural Sciences Argentine Museum in Argentina. The holotype specimen, ISIR 780, consists of a partial skull roof including the prefrontal, frontal, postfrontal and parietal bones, along with a pair of large supra-orbital horns. The various other specimens from the bone bed have been designated as paratypes and consist of multiple cranial and postcranial bones from much of the skeleton. The genus was named using the ancient Sanskrit word for "horn", 'Śṛṅga' (शृङ्ग), for the unique horns on its skull, combined with the Ancient Greek σαῦρος (sauros) for "lizard". The specific name indicus is Latin for "Indian", to refer to its country of discovery.
Classification
Shringasaurus is recognised as a member of the family Azendohsauridae, and as the closest relative of Azendohsaurus itself. The family is typically grouped within the recently recognised clade Allokotosauria, along with the trilophosaurids, as was recovered by Sengupta and colleagues when they described Shringasaurus and analysed its phylogenetic relationships in 2017. Another analysis of archosauromorph relationships in 2019 that used a different dataset from Sengupta et al. (2017)—that of Pritchard et al. (2018)—was updated to include Shringasaurus, and similarly recovered it and Azendohsaurus as each other's closest relatives within Allokotosauria, further supporting an azendohsaurid affinity for Shringasaurus.
The results found by Sengupta and colleagues in 2017 is shown below as an excerpt of the full cladogram, simplified and focused on the relationships of Shringasaurus to other allokotosaurs:
Shringasaurus and other azendohsaurids share several features, including confluent nares, leaf-shaped teeth and a long neck, as well as a few other minor details of the skeleton. It is particularly similar to Azendohsaurus in features of the parietals, the lower jaw, shoulder, hip, femur and vertebrae, but can be distinguished by teeth that are not expanded above the roots, the lack of a groove on the inside surface of the maxilla, tall neural spines, and of course the horns.
Palaeobiology
The Shringasaurus bonebed suggests that it was a gregarious animal that lived in herds. The herd appears to have died in a mass mortality event and was buried in a short span of time, possibly drowned by a breached levee. The bonebed includes juveniles, sub-adults and adults, further suggesting that Shringasaurus lived in mixed-age herds. The herd was also mixed-sex, based on the presence of both purported males and females, although it is unclear if they lived mixed-sex year round or if they only did so during part of the year, namely the breeding season (as observed in domestic sheep and related herbivores where males similarly spar with their horns). The herd was likely congregating around a nearby river channel during a period of environmental stress such as a drought, as occurs in living herbivores and has also been inferred for some dinosaurs.
Function of the horns
The horns of Shringasaurus are its most prominent feature, and so some focus was placed on their role and function in its initial description. Its describers considered its horns to be likely products of sexual selection, not primarily for defence or species recognition (as has been proposed for the head ornaments of dinosaurs). The horns grow notably larger and more robust in large adults, while smaller individuals have shorter and more graceful horns. The possibility that Shringasaurus was sexually dimorphic, with probable females lacking horns, further supports this interpretation. This would be similar to modern horned bovids, but unlike ceratopsid dinosaurs, and indeed other archosauromorphs, which do not appear to have been dimorphic.
Palaeopathology
One specimen of Shringasaurus is known to have had a pair of malformed vertebrae in its neck. The two cervicals are partially fused together, interpreted as either the result of a birth defect, spondyloarthropathy (a type of arthritis), or possibly a bacterial or fungal disc infection. The vertebrae belonged to a large adult animal, so it is unlikely that the quality of life for the individual was severely affected by the disorder, and it was probably not fatal to the animal. One of the vertebrae also preserves a healed fracture, although the cause for this injury is unknown.
Palaeoecology
In the upper Denwa Formation, Shringasaurus coexisted with the lungfish Ceratodus sp. and a variety of temnospondyl amphibians, including the capitosaurid Paracyclotosaurus crookshanki, the mastodonsaurid Cherninia denwai, a lonchorhynchine trematosaurid, and a brachyopid. Other terrestrial vertebrates include a large undescribed rhynchosaur and two species of dicynodonts, a mid-sized species similar to Kannemeyeria and a larger species interpreted as similar to Stahleckeria. The environment is interpreted as representing a dry, semi-arid floodplain with slow moving, anabranching rivers that periodically burst their banks. Rainfall was seasonal, and the environment experienced droughts that dried up ephemeral rivers and ponds. The large body size of Shringasaurus and its convergent similarity to sauropodomorphs—including its jaws and teeth as well as a superficially similar body shape—suggests that it possibly occupied the role of a large, relatively high-browsing herbivore in its environment.
| Biology and health sciences | Other prehistoric reptiles | Animals |
63429503 | https://en.wikipedia.org/wiki/Acanthosoma | Acanthosoma | Acanthosoma is a genus of shield bugs in the family Acanthosomatidae, found in Europe, Asia, and Oceania. There are over 30 described species in the genus Acanthosoma.
Species
The following species are recognised in the genus Acanthosoma:
Acanthosoma alaticorne
Acanthosoma asahinai
Acanthosoma atayal
Acanthosoma axicia
Acanthosoma chinanum
Acanthosoma cornutum
Acanthosoma crassicaudum
Acanthosoma debile
Acanthosoma denticaudum
Acanthosoma emeiense
Acanthosoma expansum
Acanthosoma fallax
Acanthosoma firmatum
Acanthosoma forcipatum
Acanthosoma forfex
Acanthosoma forficula
Acanthosoma haemorrhoidale - Hawthorn Shieldbug
Acanthosoma hampsoni
Acanthosoma ishiharai
Acanthosoma joursacensis
Acanthosoma labiduroides
Acanthosoma laevicorne
Acanthosoma livida
Acanthosoma maculata
Acanthosoma montanum
Acanthosoma morloti
Acanthosoma murreeanum
Acanthosoma nigricorne
Acanthosoma nigrodorsum
Acanthosoma pteridis
Acanthosoma pugnax
Acanthosoma rufescens
Acanthosoma rufispinum
Acanthosoma shensiense
Acanthosoma sichuanense
Acanthosoma sinense
Acanthosoma sp.
Acanthosoma sp.
Acanthosoma spinicolle
Acanthosoma tauriforme
Acanthosoma taurina
BOLD:AAJ3749 (Acanthosoma sp.)
| Biology and health sciences | Hemiptera (true bugs) | Animals |
62557527 | https://en.wikipedia.org/wiki/Fresh%20water | Fresh water | Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mineral-rich waters, such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes.
Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of vascular plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive.
Fresh water is the water resource that is of the most and immediate use to humans. Fresh water is not always potable water, that is, water safe to drink by humans. Much of the earth's fresh water (on the surface and groundwater) is to a substantial degree unsuitable for human consumption without treatment. Fresh water can easily become polluted by human activities or due to naturally occurring processes, such as erosion.
Fresh water makes up less than 3% of the world's water resources, and just 1% of that is readily available. About 70% of the world's freshwater reserves are frozen in Antarctica. Just 3% of it is extracted for human consumption. Agriculture uses roughly two thirds of all fresh water extracted from the environment.
Fresh water is a renewable and variable, but finite natural resource. Fresh water is replenished through the process of the natural water cycle, in which water from seas, lakes, forests, land, rivers and reservoirs evaporates, forms clouds, and returns inland as precipitation. Locally, however, if more fresh water is consumed through human activities than is naturally restored, this may result in reduced fresh water availability (or water scarcity) from surface and underground sources and can cause serious damage to surrounding and associated environments. Water pollution also reduces the availability of fresh water. Where available water resources are scarce, humans have developed technologies like desalination and wastewater recycling to stretch the available supply further. However, given the high cost (both capital and running costs) and - especially for desalination - energy requirements, those remain mostly niche applications.
A non-sustainable alternative is using so-called "fossil water" from underground aquifers. As some of those aquifers formed hundreds of thousands or even millions of years ago when local climates were wetter (e.g. from one of the Green Sahara periods) and are not appreciably replenished under current climatic conditions - at least compared to drawdown, these aquifers form essentially non-renewable resources comparable to peat or lignite, which are also continuously formed in the current era but orders of magnitude slower than they are mined.
Definitions
Numerical definition
Fresh water can be defined as water with less than 500 parts per million (ppm) of dissolved salts.
Other sources give higher upper salinity limits for fresh water, e.g. 1,000 ppm or 3,000 ppm.
Systems
Fresh water habitats are classified as either lentic systems, which are the stillwaters including ponds, lakes, swamps and mires; lotic which are running-water systems; or groundwaters which flow in rocks and aquifers. There is, in addition, a zone which bridges between groundwater and lotic systems, which is the hyporheic zone, which underlies many larger rivers and can contain substantially more water than is seen in the open channel. It may also be in direct contact with the underlying underground water.
Sources
The original source of almost all fresh water is precipitation from the atmosphere, in the form of mist, rain and snow. Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea and land over which the rain bearing clouds have traveled. The precipitation leads eventually to the formation of water bodies that humans can use as sources of freshwater: ponds, lakes, rainfall, rivers, streams, and groundwater contained in underground aquifers.
In coastal areas fresh water may contain significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium, chloride, magnesium and sulfate as well as many other compounds in smaller concentrations.
In desert areas, or areas with impoverished or dusty soils, rain-bearing winds can pick up sand and dust and this can be deposited elsewhere in precipitation and causing the freshwater flow to be measurably contaminated both by insoluble solids but also by the soluble components of those soils. Significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa.
In Africa, it was revealed that groundwater controls are complex and do not correspond directly to a single factor. Groundwater showed greater resilience to climate change than expected, and areas with an increasing threshold between 0.34 and 0.39 aridity index exhibited significant sensitivity to climate change. Land-use could affect infiltration and runoff processes. The years of most recharge coincided with the most precipitation anomalies, such as during El Niño and La Niña events. Three precipitation-recharge sensitivities were distinguished: in super arid areas with more than 0.67 aridity index, there was constant recharge with little variation with precipitation; in most sites (arid, semi-arid, humid), annual recharge increased as annual precipitation remained above a certain threshold; and in complex areas down to 0.1 aridity index (focused recharge), there was very inconsistent recharge (low precipitation but high recharge). Understanding these relationships can lead to the development of sustainable strategies for water collection. This understanding is particularly crucial in Africa, where water resources are often scarce and climate change poses significant challenges.
Water distribution
Saline water in oceans, seas and saline groundwater make up about 97% of all the water on Earth. Only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers, ice and snow, 0.5–0.75% as fresh groundwater. The water table is the level below which all spaces are filled with water, while the area above this level, where spaces in the rock and soil contain both air and water, is known as the unsaturated zone. The water in this unsaturated zone is referred to as soil moisture.
Below the water table, the entire region is known as the saturated zone, and the water in this zone is called groundwater. Groundwater plays a crucial role as the primary source of water for various purposes including drinking, washing, farming, and manufacturing, and even when not directly used as a drinking water supply it remains vital to protect due to its ability to carry contaminants and pollutants from the land into lakes and rivers, which constitute a significant percentage of other people's freshwater supply. It is almost ubiquitous underground, residing in the spaces between particles of rock and soil or within crevices and cracks in rock, typically within of the surface, and soil moisture, and less than 0.01% of it as surface water in lakes, swamps and rivers.
Freshwater lakes contain about 87% of this fresh surface water, including 29% in the African Great Lakes, 22% in Lake Baikal in Russia, 21% in the North American Great Lakes, and 14% in other lakes. Swamps have most of the balance with only a small amount in rivers, most notably the Amazon River. The atmosphere contains 0.04% water. In areas with no fresh water on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers. Most of the world's fresh water is frozen in ice sheets. Many areas have very little fresh water, such as deserts.
Freshwater ecosystems
Water is a critical issue for the survival of all living organisms. Some can use salt water but many organisms including the great majority of higher plants and most mammals must have access to fresh water to live. Some terrestrial mammals, especially desert rodents, appear to survive without drinking, but they do generate water through the metabolism of cereal seeds, and they also have mechanisms to conserve water to the maximum degree.
Challenges
The increase in the world population and the increase in per capita water use puts increasing strains on the finite resources availability of clean fresh water. The response by freshwater ecosystems to a changing climate can be described in terms of three interrelated components: water quality, water quantity or volume, and water timing. A change in one often leads to shifts in the others as well.
Limited resource
Minimum streamflow
An important concern for hydrological ecosystems is securing minimum streamflow, especially preserving and restoring instream water allocations. Fresh water is an important natural resource necessary for the survival of all ecosystems.
Water pollution
Society and culture
Human uses
Uses of water include agricultural, industrial, household, recreational and environmental activities.
Global goals for conservation
The Sustainable Development Goals are a collection of 17 interlinked global goals designed to be a "blueprint to achieve a better and more sustainable future for all". Targets on fresh water conservation are included in SDG 6 (Clean water and sanitation) and SDG 15 (Life on land). For example, Target 6.4 is formulated as "By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce the number of people suffering from water scarcity." Another target, Target 15.1, is: "By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains and drylands, in line with obligations under international agreements."
| Physical sciences | Water: General | Earth science |
55053716 | https://en.wikipedia.org/wiki/GW170817 | GW170817 | GW170817 was a gravitational wave (GW) signal observed by the LIGO and Virgo detectors on 17 August 2017, originating from the shell elliptical galaxy NGC 4993, about 140 million light years away. The signal was produced by the last moments of the inspiral process of a binary pair of neutron stars, ending with their merger. , it is the only GW detection to be definitively correlated with any electromagnetic observation. Unlike the five prior GW detections—which were of merging black holes and thus not expected to have detectable electromagnetic signals—the aftermath of this merger was seen across the electromagnetic spectrum by 70 observatories on 7 continents and in space, marking a significant breakthrough for multi-messenger astronomy. The discovery and subsequent observations of GW170817 were given the Breakthrough of the Year award for 2017 by the journal Science.
The gravitational wave signal, designated GW170817, had an audible duration of approximately 100 seconds, and showed the characteristic intensity and frequency expected of the inspiral of two neutron stars. Analysis of the slight variation in arrival time of the GW at the three detector locations (two LIGO and one Virgo) yielded an approximate angular direction to the source. Independently, a short gamma-ray burst (sGRB) of around 2 seconds, designated GRB 170817A, was detected by the Fermi and INTEGRAL spacecraft beginning 1.7 seconds after the GW merger signal. These detectors have very limited directional sensitivity, but indicated a large area of the sky which overlapped the gravitational wave position. The co-occurrence confirmed a long-standing hypothesis that neutron star mergers describe an important class of sGRB progenitor event.
An intense observing campaign was prioritized, to scan the region indicated by the gravitational wave detection for the expected emission at optical wavelengths. During this search, 11 hours after the signal, an astronomical transient SSS17a, later designated kilonova AT 2017gfo, was observed in the galaxy . It was captured by numerous telescopes, from radio to X-ray wavelengths, over the following days and weeks, and was found to be a fast-moving, rapidly-cooling cloud of neutron-rich material, as expected of debris ejected from a neutron-star merger.
In October 2018, astronomers reported that, in retrospect, an sGRB event detected in 2015 () may represent an earlier case of the same astrophysics reported for GW170817. The similarities between the two events in terms of gamma ray, optical, and x-ray emissions, as well as to the nature of the associated host galaxies, were considered "striking", suggesting that the earlier event may also be the result of a neutron star merger, and that together these may signify a hitherto-unknown class of kilonova transients, making kilonovae more diverse and common in the universe than previously understood. Later research further construed —another sGRB predating GW170817—also to be a kilonova, again based its resemblance to the signature.
Announcement
The observations were officially announced on 16 October 2017 at press conferences at the National Press Club in Washington, D.C., and at the ESO headquarters in Garching bei München in Germany.
Some information was leaked before the official announcement, beginning on 18 August 2017 when astronomer J. Craig Wheeler of the University of Texas at Austin tweeted "New LIGO. Source with optical counterpart. Blow your sox off!" He later deleted the tweet and apologized for scooping the official announcement embargo. Other people followed up on the rumor, and reported that the public logs of several major telescopes listed priority interruptions in order to observe , a galaxy away in the Hydra constellation. The collaboration had earlier declined to comment on the rumors, not adding to a previous announcement that there were several triggers under analysis.
Gravitational wave detection
The gravitational wave signal lasted for approximately 100 seconds starting from a frequency of 24 hertz. It covered approximately 3,000 cycles, increasing in amplitude and frequency to a few hundred hertz in the typical inspiral chirp pattern, ending with the collision received at 12:41:04.4 UTC. It arrived first at the Virgo detector in Italy, then 22 milliseconds later at the LIGO-Livingston detector in Louisiana, United States, and another 3 milliseconds later at the LIGO-Hanford detector in the state of Washington, in the United States. The signal was detected and analyzed by a comparison with a prediction from general relativity defined from the post-Newtonian expansion.
An automatic computer search of the LIGO-Hanford datastream triggered an alert to the LIGO team about 6 minutes after the event. The gamma-ray alert had already been issued at this point (16 seconds post-event), so the timing near-coincidence was automatically flagged. The LIGO/Virgo team issued a preliminary alert (with only the crude gamma-ray position) to astronomers in the follow-up teams at 40 minutes post-event.
Sky localisation of the event required combining data from the three interferometers, but this was delayed by two problems. The Virgo data were delayed by a data transmission problem, and the LIGO Livingston data were contaminated by a brief burst of instrumental noise a few seconds prior to the event peak, which persisted parallel to the rising transient signal in the lowest frequencies. These required manual analysis and interpolation before the sky location could be announced about 4.5 hours after the event. The three detections localized the source to an area of 31 square degrees in the southern sky at 90% probability. More detailed calculations later refined the localization to within 28 square degrees. In particular, the absence of a clear detection by the Virgo interferometer implied that the source was localized within one of its blind spots, a constraint which reduced the search area considerably.
Gamma ray detection
The first electromagnetic signal detected was GRB 170817A, a short gamma-ray burst, detected after the merger time and lasting for about 2 seconds.
GRB 170817A was first recorded by the Fermi Gamma-ray Space Telescope, which issued an automatic alert just 14 seconds after the detection. After the LIGO/Virgo circular 40 minutes later, manual processing of data from the INTEGRAL gamma-ray telescope retrieved independent data for the event. The difference in arrival time between Fermi and INTEGRAL helped to improve the sky localization.
This GRB was relatively faint given the proximity of the host galaxy , possibly due to its jets not being pointed directly toward Earth, but rather at an angle of about 30 degrees off axis.
Electromagnetic follow-up
A series of alerts to other astronomers were issued, beginning with a report of the gamma-ray detection and single-detector LIGO trigger at 13:21 UTC, and a three-detector sky location at 17:54 UTC. These prompted a massive search by many survey and robotic telescopes. In addition to the expected large size of the search area (about 150 times the area of a full moon), this search was challenging because the search area was near the Sun in the sky and thus visible for at most a few hours after dusk for any given telescope.
In total six teams (One-Meter, Two Hemispheres (1M2H), DLT40, VISTA, Master, DECam, and Las Cumbres Observatory (Chile)) imaged the same new source independently in a 90-minute interval. The first to detect optical light associated with the collision was the 1M2H team running the Swope Supernova Survey, which found it in an image of taken 10 hours and 52 minutes after the GW event by the Swope Telescope operating in the near infrared at Las Campanas Observatory, Chile. They were also the first to announce it, naming their detection SSS17a in a circular issued 1226 post-event. The new source was later given an official International Astronomical Union (IAU) designation AT 2017gfo.
The 1M2H team surveyed all galaxies in the region of space predicted by the gravitational wave observations, and identified a single new transient. By identifying the host galaxy of the merger, it is possible to provide an accurate distance consistent with that based on gravitational waves alone.
The detection of the optical and near-infrared source provided a huge improvement in localisation, reducing the uncertainty from several degrees to 0.0001 degree; this enabled many large ground and space telescopes to follow up the source over the following days and weeks.
Within hours after localization, many additional observations were made across the infrared and visible spectrum. Over the following days, the color of the optical source changed from blue to red as the source expanded and cooled.
Numerous optical and infrared spectra were observed; early spectra were nearly featureless, but after a few days, broad features emerged indicative of material ejected at roughly 10 percent of light speed. There are multiple strong lines of evidence that AT 2017gfo is indeed the aftermath of GW170817. The color evolution and spectra are dramatically different from any known supernova. The distance of NGC 4993 is consistent with that independently estimated from the GW signal. No other transient has been found in the GW sky localisation region. Finally, various archive images show nothing at the location of AT 2017gfo, ruling out a foreground variable star in the Milky Way.
The source was detected in the ultraviolet (but not in X-rays) 15.3 hours after the event by the Swift Gamma-Ray Burst Mission. After initial lack of X-ray and radio detections, the source was detected in X-rays 9 days later using the Chandra X-ray Observatory, and 16 days later in the radio using the Karl G. Jansky Very Large Array (VLA) in New Mexico. More than 70 observatories covering the electromagnetic spectrum observed the source.
The radio and X-ray light increased to a peak 150 days after the merger, diminishing afterwards. Astronomers have monitored the optical afterglow of GW170817 using the Hubble Space Telescope. In March 2020, continued X-ray emission at 5-sigma was observed by the Chandra Observatory 940 days after the merger.
Other detectors
No neutrinos consistent with the source were found in follow-up searches by the IceCube and ANTARES neutrino observatories and the Pierre Auger Observatory. A possible explanation for the non-detection of neutrinos is because the event was observed at a large off-axis angle and thus the outflow jet was not directed towards Earth.
Astrophysical origin and products
The origin and properties (masses and spins) of a double neutron star system like GW170817 are the result of a long sequence of complex binary star interactions. The gravitational wave signal indicated that it was produced by the collision of two neutron stars with a total mass of solar masses (). If low spins are assumed, consistent with those observed in binary neutron stars that will merge within a Hubble time, the total mass is . The total energy output of the gravitational wave was ≃63 Foe.
The masses of the progenitor stars have greater uncertainty. The chirp mass, a directly observable parameter which may be roughly equated to the geometric mean of the prior masses, was measured at . The larger progenitor () has a 90% chance of being between , and the smaller () has a 90% chance of being between . Under the low spin assumption, the ranges are for and for , inside a 12 km radius.
The neutron star merger event resulted in a spherically expanding kilonova, characterized by a short gamma-ray burst followed by a longer optical afterglow powered by the radioactive decay of heavy r-process nuclei. GW170817 therefore confirmed neutron star mergers to be viable sites for the r-process, where the neucleosynthesis of around half the isotopes in elements heavier than iron can occur. A total of 16,000 times the mass of the Earth in heavy elements is believed to have formed, including approximately 10 Earth masses just of the two elements gold and platinum.
A hypermassive neutron star was believed to have formed initially, as evidenced by the large amount of ejecta (much of which would have been swallowed by an immediately forming black hole). At first, the lack of evidence for emissions being powered by neutron star spindown, which would occur for longer-surviving neutron stars, suggested it collapsed into a black hole within milliseconds. However, a more detailed analysis of the GW170817 signal tail later found evidence of further features consistent with the seconds-long spindown of an intermediate or remnant hypermassive magnetar, the energy of which was below the estimated sensitivity of the LIGO search algorithms at the time. This was confirmed in 2023 by a statistically independent method of analysis revealing the central engine of GRB170817A. , the precise nature of the ultimately stable remnant remains uncertain.
Scientific importance
Scientific interest in the event was enormous, with dozens of preliminary papers (and almost 100 preprints) published the day of the announcement, including 8 letters in Science, 6 in Nature, and 32 in a special issue of The Astrophysical Journal Letters devoted to the subject. The interest and effort was global: The paper describing the multi-messenger observations is coauthored by almost 4,000 astronomers (about one-third of the worldwide astronomical community) from more than 900 institutions, using more than 70 observatories on all 7 continents and in space.
The event also provided a limit on the difference between the speed of light and that of gravity. Assuming the first photons were emitted between zero and ten seconds after peak gravitational wave emission, the difference between the speeds of gravitational and electromagnetic waves, vGW − vEM, is constrained to between −3×10−15 and +7×10−16 times the speed of light, which improves on the previous estimate by about 14 orders of magnitude.
In addition, GW170817 allowed investigation of the equivalence principle (through Shapiro delay measurement) and Lorentz invariance. The limits of possible violations of Lorentz invariance (values of 'gravity sector coefficients') are reduced by the new observations by up to ten orders of magnitude.
The event also excluded some alternatives to general relativity, including variants of scalar–tensor theory, Hořava–Lifshitz gravity, Dark Matter Emulators, and bimetric gravity, Furthermore, an analysis published in July 2018 used GW170817 to show that gravitational waves propagate fully through the 3+1 curved spacetime described by general relativity, ruling out hypotheses involving "leakage" into higher, non-compact spatial dimensions.
Gravitational wave signals such as GW170817 may be used as a standard siren to provide an independent measurement of the Hubble constant. An initial estimate of the constant derived from the observation is (km/s)/Mpc, broadly consistent with current best estimates. Further studies improved the measurement to (km/s)/Mpc. Together with the observation of future events of this kind, the uncertainty is expected to reach two percent within five years and one percent within ten years.
Electromagnetic observations help support the theory that neutron star mergers contribute to rapid neutron capture (r-process) nucleosynthesis—previously assumed to be associated with supernova explosions—and are therefore the primary source of r-process elements heavier than iron, including gold and platinum. The first identification of r-process elements in a neutron star merger was obtained during a re-analysis of GW170817 spectra. The spectra provided direct proof of strontium production during a neutron star merger. This also provided the most direct proof that neutron stars are made of neutron-rich matter. Since then, several r-process elements have been identified in the ejecta including yttrium, lanthanum and cerium.
In October 2017, Stephen Hawking, in his last broadcast interview, discussed the overall scientific importance of GW170817. In September 2018, astronomers reported related studies about possible mergers of neutron stars (NS) and white dwarfs (WD): including NS-NS, NS-WD, and WD-WD mergers.
| Physical sciences | Notable transient events | Astronomy |
59882582 | https://en.wikipedia.org/wiki/Vaccines%20and%20autism | Vaccines and autism | Extensive investigation into vaccines and autism spectrum disorder has shown that there is no relationship between the two, causal or otherwise, and that vaccine ingredients do not cause autism. The American scientist Peter Hotez researched the growth of the false claim and concluded that its spread originated with Andrew Wakefield's fraudulent 1998 paper, and that no prior paper supports a link.
Despite the scientific consensus for the absence of a relationship and the retracted paper, the anti-vaccination movement at large continues to promote theories linking the two. A developing tactic appears to be the "promotion of irrelevant research [as] an active aggregation of several questionable or peripherally related research studies in an attempt to justify the science underlying a questionable claim."
Claimed mechanisms
The claimed mechanisms have changed over time, in response to evidence refuting each in turn. The CDC published updated statistics on autism in children for the year 2020. It states that in the year 2000, there were 1 in 150 children who were born in 1992 diagnosed with autism. In 2020, they found 1 in 36 children born in 2012 were diagnosed with autism. Anti-vaccination groups believe this to be the increased number of vaccines in children. Although there has been an increase in vaccines, there has been an increase in autism screenings. It is clear from the literature and the CDC the increased number of children diagnosed with autism is due to the increase in ways to diagnose it. The anti-vaccine groups credit ingredients in the vaccines to be the connection to autism. Some of the most mentioned ones are thiomersal, aluminum adjuvants, and formaldehyde. The MMR vaccine will be explained as well. Celebrity and social media involvement seem to play a role in the anti-vaccine movement.
Autism screening history
In the early 2000s, evidence-based tools were being used for children as early as 36 months to help with the diagnosis of autism, and parents of children were able to identify signs of autism by the time the child turned 2.
In 2001, the Modified Autism Checklist for Toddlers (M-CHAT) was used and could diagnose children with signs of autism at 24 months.
In 2006, the American Academy of Pediatricians mandated screening, specifically for autism, at a child's 18-month checkup and later mandated for the 24-month visit as well.
As of May 2024, the CDC mentioned that healthcare workers, community members, and even schools can screen for autism. The diagnosis of autism in a child by the age of two conducted by a professional is evaluated as very reliable.
Vaccine-derived measles virus
The idea of a link between the MMR vaccine and autism came to prominence after the publication of a paper by Andrew Wakefield and others in The Lancet in 1998. This paper, which was retracted in 2010 and whose publication led to Wakefield being struck off the United Kingdom medical register, has been described as "the most damaging medical hoax of the last 100 years".
Wakefield's primary claim was that he had isolated evidence of vaccine-strain measles virus RNA in the intestines of autistic children, leading to a condition he termed autistic enterocolitis (a condition never recognised or adopted by the scientific community). This finding was later shown to be due to errors made by the laboratory where the polymerase chain reaction (PCR) tests were performed.
In 2009, The Sunday Times reported that Wakefield had manipulated patient data and misreported results in his 1998 paper, thus falsifying a link with autism. A 2011 article in the British Medical Journal describes the way in which Wakefield manipulated the data in his study in order to arrive at his predetermined conclusion. An accompanying editorial in the same journal described Wakefield's work as an "elaborate fraud" which led to lower vaccination rates, putting hundreds of thousands of children at risk and diverting funding and other resources from research into the true cause of autism.
On 12 February 2009, a special court convened in the United States to review claims under its National Vaccine Injury Compensation Program ruled that parents of autistic children are not entitled to compensation in their contention that certain vaccines caused their children to develop autism.
The Centers for Disease Control and Prevention (CDC), the IOM of the United States National Academy of Sciences, and the National Health Service have all concluded that there is no link between the MMR vaccine and autism. A systematic review by the Cochrane Library concluded that there is no credible link between the MMR vaccine and autism, that the MMR vaccine has prevented diseases that still carry a heavy burden of death and complications, that the lack of confidence in the MMR vaccine has damaged public health, and that the design and reporting of safety outcomes in MMR vaccine studies are largely inadequate. Further, an epidemiology study concluded that even children labeled high risk for autism, due to an older autistic sibling, that received the MMR vaccine resulted in no causal connection between the vaccine and autism or the increased risk of being diagnosed with autism. The assumption that MMR vaccines cause autism is not isolated to the United States. A seven-year study was done in Denmark from 1991 to 1998 following children who received the MMR vaccine. The results of the study found that when comparing the vaccinated children to the unvaccinated children, the risk of autism in the vaccinated group was 0.92. Also, the risk of another autism disorder was 0.83. The study concluded there was no association between the MMR vaccine and autism. The result held even when exploring the age of the child when the vaccine was given, the vaccination date, or the amount of time after the vaccine.
Thiomersal
Thiomersal is an antifungal preservative used in small amounts in some multi-dose vaccines (where the same vial is opened and used for multiple patients) to prevent contamination of the vaccine. Thiomersal contains ethylmercury, a mercury compound which is related to, but significantly less toxic than, the neurotoxic pollutant methylmercury. Despite decades of safe use, public campaigns prompted the CDC and the American Academy of Pediatrics (AAP) to request vaccine makers to remove thiomersal from vaccines as quickly as possible on the precautionary principle. Thiomersal is now absent from all common United States and European Union vaccines, except for some preparations of influenza vaccine. (Trace amounts remain in some vaccines due to production processes, at an approximate maximum of 1 microgramme, around 15% of the average daily mercury intake in the US for adults and 2.5% of the daily level considered tolerable by the World Health Organization [WHO].) The action engendered concern thiomersal could have been responsible for autism.
The idea that thiomersal was a cause or trigger for autism is now considered disproven, as incidence rates for autism increased steadily even after thiomersal was removed from childhood vaccines. The cause of autism and mercury poisoning being associated is improbable because the symptoms of mercury poisoning are not present and are inherently inconsistent with the behaviors or symptoms of autism. There is no accepted scientific evidence that exposure to thiomersal is a factor in causing autism. A study by the CDC exploring mercury poisoning in vaccines concluded no signs of poisoning were present.
Under the U.S. Food and Drug Administration (FDA) Modernization Act (FDAMA) of 1997, the FDA conducted a comprehensive review of the use of thiomersal in childhood vaccines. Conducted in 1999, this review found no evidence of harm from the use of thiomersal as a vaccine preservative, other than local hypersensitivity reactions. Despite this, starting in 2000, parents in the United States pursued legal compensation from a federal fund arguing that thiomersal caused autism in their children. A 2004 Institute of Medicine (IOM) committee favored rejecting any causal relationship between autism and vaccines containing thiomersal and rulings from the vaccine court in three test claims in 2010 established the precedent that thiomersal is not considered a cause of autism.
Vaccine overload
Following the belief that individual vaccines caused autism was the idea of vaccine overload, which claims that too many vaccines at once may overwhelm or weaken a child's immune system and lead to adverse effects. The Children's Hospital of Philadelphia Vaccine Education Center compiled a list of vaccines recommended to children throughout history. They found that from 1985-1994, the recommended number of vaccines totaled to eight. The schedule for 2011 to 2020 revealed the recommended number of vaccines totaled to fourteen. Vaccine overload became popular after the Vaccine Injury Compensation Program in the United States accepted the case of nine-year-old Hannah Poling. Poling had encephalopathy, putting her on the autism spectrum disorder, which was believed to have worsened after getting multiple vaccines at nineteen months old. There have been multiple cases reported similar to this one, which led to the belief that vaccine overload caused autism. However, scientific studies show that vaccines do not overwhelm the immune system. In fact, conservative estimates predict that the immune system can respond to thousands of viruses simultaneously. It is known that vaccines constitute only a tiny fraction of the pathogens already naturally encountered by a child in a typical year. Common fevers and middle ear infections pose a much greater challenge to the immune system than vaccines do. Other scientific findings support the idea that vaccinations, and even multiple concurrent vaccinations, do not weaken the immune system or compromise overall immunity and evidence that autism has any immune-mediated pathophysiology has still not been found.
Vaccines recommended from 1985-1994:
Diphtheria
Tetanus
Pertussis
Measles
Mumps
Rubella
Polio
Hib
Hepatitis B (1991)
Vaccines recommended from 2011-2020:
Diphtheria
Tetanus
Pertussis
Measles
Mumps
Rubella
Polio
Hib
Hepatitis B
Varicella
Hepatitis A
Pneumococcal
Influenza
Rotavirus
Diphtheria, Tetanus, and Pertussis were given together as the DTap. Measles, Mumps, and Rubella were given together as MMR.
Aluminium adjuvants
As mercury compounds in vaccines have been definitively ruled out as a cause of autism, some anti-vaccine activists propose aluminium adjuvants as the cause of autism. Aluminium adjuvants, simulates immune receptors and causes a strengthened response to the antigen in a way that is natural to the body. Aluminium adjuvants can be used in the form of soluble salts, alumina, and hydroxl. There is no substantial scientific evidence that aluminium adjuvants are linked to autism. When confirming that aluminium adjuvants are not dangerous in vaccines, it was concluded that there was no traces of aluminium in the children's hair or blood over the minimum level of risks according to the Agency for Toxic Substances and Disease Registry. Anti-vaccination activists commonly cite a number of papers which claim that there is in fact a link. These are mainly published in predatory open access journals, where peer-review is virtually non-existent. Work conducted by Christopher Shaw, Christopher Exley and Lucija Tomljenovic has been funded by the anti-vaccination Dwoskin Family Foundation. The work published by Shaw et al. has been discredited by the World Health Organization.
Formaldehyde
Formaldehyde is another assumed link between vaccines and autism. Even though the assumption still circles around, formaldehyde has been used safely in the diphtheria vaccines to detoxify the bacteria used to make the vaccine. Another way it can be used is to inactivate the disease to be used in the vaccine. Formaldehyde can be found naturally in the body and environment. The human body uses formaldehyde to build amino acids and to generate the energy we need. Formaldehyde is all around us in daily life activities. It can be found in preservatives, materials used to build, and many products in homes. There is no safety concern for formaldehyde in vaccines. The most concerning repercussion is cancer after exposure to high levels of formaldehyde in the air. The amount of formaldehyde in some vaccines is less than what the body naturally produces.
Celebrity involvement and social media
Some celebrities have spoken out on their views that autism is related to vaccination, including: Jenny McCarthy, Kristin Cavallari, Robert De Niro, Jim Carrey, Bill Maher, and Pete Evans.
McCarthy, one of the most outspoken celebrities on the topic, has said her son Evan's autism diagnosis was a result of the MMR vaccine. She authored Louder than Words: A Mother's Journey in Healing Autism and co-authored Healing and Preventing Autism. She also founded Generation Rescue, an organisation which provides resources for families affected by autism.
In a September 2015 U.S. presidential debate, Republican Party candidate and future United States President Donald Trump stated he knew of a 2-year-old child who had recently received a combined vaccine, developed a fever, and subsequently autism.
Robert F. Kennedy, Jr. is one of the most notable proponents of the anti-vaccine movement. Kennedy published the book Thimerosal: Let the Science Speak: The Evidence Supporting the Immediate Removal of Mercury--A Known Neurotoxin--From Vaccines. He is also chairman of the board of Children's Health Defense, a group and website widely known for its anti-vaccination stance.
A study conducted through Facebook explored the results of anti-vaccine ads and pro-vaccine ads. The study found that even with a similar number of anti-vaccine ads and pro-vaccine ads, the middle point in the data set of ads per buyer was higher in anti-vaccine ads. Another difference the study revealed was that the anti-vaccine ads were primarily targeted toward women and young adults who possibly had children. The pro-vaccination ads were presented evenly to different ages.
Public opinion
In December 2020, a poll of 1,115 U.S. adults found 12% of respondents believed there is evidence vaccinations cause autism; 51% believed there is no evidence; and 37% did not know.
An updated survey, conducted in March 2023, concluded that adults think the MMR health benefits are high/very high, at 72%, and the risk of side effects is low/very low, at 64%. There has also been a drop from 2019 in United States adults who believe students in schools should be fully vaccinated. The 2023 survey showed that a decrease to 70% of U.S. adults agree that children should be vaccinated for school but an increase to 28% believe that it is the parent's right to choose if the child is vaccinated for school.
| Biology and health sciences | Vaccines | Health |
58261265 | https://en.wikipedia.org/wiki/Goby | Goby | Goby is a common name for many species of small to medium sized ray-finned fish, normally with large heads and tapered bodies, which are found in marine, brackish and freshwater environments.
Traditionally most of the species called gobies have been classified in the order Perciformes as the suborder Gobioidei but in the 5th Edition of Fishes of the World this suborder is elevated to an order Gobiiformes within the clade Percomorpha. Not all the species in the Gobiiformes are referred to as gobies and the "true gobies" are placed in the family Gobiidae, while other species referred to as gobies have been placed in the Oxudercidae. Goby is also used to describe some species which are not classified within the order Gobiiformes, such as the engineer goby or convict blenny Pholidichthys leucotaenia. The word goby derives from the Latin gobius meaning "gudgeon", and some species of goby, especially the sleeper gobies in the family Eleotridae and some of the dartfishes are called "gudgeons", especially in Australia.
| Biology and health sciences | Acanthomorpha | null |
58290264 | https://en.wikipedia.org/wiki/Jacanidae | Jacanidae | The jacanas (sometimes referred to as Jesus birds or lily trotters) are a group of tropical waders in the family Jacanidae. They are found in the tropical regions around the world. They are noted for their elongated toes and toenails that allow them to spread out their weight while foraging on floating or semi-emergent aquatic vegetation. They are also among the somewhat rare groups of birds in which females are larger, and several species maintain harems of males in the breeding season with males solely responsible for incubating eggs and taking care of the chicks.
Taxonomy
The family Jacanidae was introduced in 1854 by the French naturalists Jean-Charles Chenu and Marc des Murs. They used the spelling "Jacaneinae". The modern spelling "Jacanidae" was used by Leonhard Stejneger in 1885.
The pronunciation of the word jacana is debated. Jacana is Linnæus' scientific Latin spelling of the Portuguese jaçanã which in turn is derived from a Tupi name of the bird, ñaha'nã. The Portuguese word is pronounced approximately . As in façade, Provençal, and araçari, the Ç is meant to be pronounced as an S. US dictionaries give various pronunciations: , , as well as the anglicised , which is the only pronunciation in an Australian dictionary. A British dictionary gives for the spelling "jacana" and for "jaçana".
Diversity
Eight species of extant jacana are known from six genera and four fossil species have been described from the Oligocene of Egypt and from the Pliocene of Florida. A fossil from Miocene strata in the Czech Republic was assigned to this family, but more recent analysis disputes the placement and moves the species to the Coraciidae.
Jacanas are identifiable by their elongated toes and claws which enable them to walk on floating vegetation in the shallow lakes that are their preferred habitat. They have sharp bills and rounded wings, some with carpal spurs, and many species also have wattles and frontal lappets on their foreheads. Jacanas were once placed in the family Parridae based on the genus Parra but the family name is now Jacanidae based on the type genus Jacana. The family is placed within the order Charadriiformes under the suborder Scolopaci and is a sister of the Rostratulidae. They have 10 tail feathers unlike most others wader groups which have twelve. They have a rudimentary caecum. Most jacanas have five neck vertebrae with the exception of Hydrophasianus chirurgus which has six.
In terms of sexual size dimorphism, female jacanas are larger than the males but are alike in plumage. The latter, as in some other wader families like the phalaropes, take responsibility for incubation and care of chicks, and most species (with the exception of the monogamous lesser jacana) are polyandrous. They construct relatively flimsy nests on floating vegetation, and lay eggs with dark irregular lines on their shells, providing camouflage amongst water weeds. The eggs are slightly smaller than in comparable species and it has been considered that this may be due to an evolutionary tradeoff given the larger number of clutches that are laid. Male jacanas brood eggs between the wings and the body. This wing-brooding may be assisted by a special adaptation in the wing bones with either a broadening of the radius or a widening of the gap between the radius and ulna. Young chicks may also be held under the wing and transported to safety by the parent bird in some species. Young chicks dive underwater and stay submerged with only their bill out of water. Some adult jacanas also use the same technique. African jacanas go through a simultaneous moult of their flight feathers leading to a period of flightlessness. Their moult is related to their ability to breed opportunistically based on the availability of rains.
Their diet consists mainly of insects and other invertebrates picked from floating vegetation or the water's surface but plant seeds may also be eaten. Wattled jacanas are known to pick ticks off capybaras. The stomach contents of jacanas have been found to include algae, as well as plant roots and stems, but it is thought that this may be incidentally ingested along with their invertebrate prey.
Most species have rounded wings and short tails. The flight tends to be slow and weak. Most species are sedentary, but the pheasant-tailed jacana migrates from the north of its range into peninsular India and southeast Asia.
Species
| Biology and health sciences | Charadriiformes | Animals |
66412282 | https://en.wikipedia.org/wiki/Climate%20change%20in%20Brazil | Climate change in Brazil | Climate change in Brazil is mainly the climate of Brazil getting hotter and drier. The greenhouse effect of excess carbon dioxide and methane emissions makes the Amazon rainforest hotter and drier, resulting in more wildfires in Brazil. Parts of the rainforest risk becoming savanna.
Brazil's greenhouse gas emissions per person are higher than the global average, and Brazil is among the countries which emit a large amount of greenhouse gases. Greenhouse gas emissions by Brazil are almost 3% of the annual world total, firstly due to cutting down trees in the Amazon rainforest, which emitted more carbon dioxide in the 2010s than it absorbed, and secondly from large cattle farms, where cows belch methane. In the Paris Agreement, Brazil promised to reduce its emissions, but the Bolsonaro government between 2019 and 2022 has been criticized for doing too little to limit climate change or adapt to climate change.
Greenhouse gas emissions
In 2020, official figures were reported for 2016: agriculture 33.2%, energy sector 28.9%, land use, land-use change, and forestry (LULUCF) 27.1%. Industrial Processes and Product Use (IPPU) and waste contributed 6.4% and 4.5%, respectively.
According to the Brazilian Climate Observatory, the country emitted 2.17 billion gross tons of carbon dioxide equivalent (te) in 2019. Deforestation accounted for 968 million te, which was 44% of the total, agriculture emitted 598.7 million te (28%) and the energy sector 413.6 million te (19%), industry 99 million te (5%) and waste 96 million te (4%).
Emissions for 2019 are estimated at 2.8% of the world total. , Brazil is the 4th heaviest cumulative emitter at 110 Gt. In 2019, on average, Brazilians emitted 10 gross tons of equivalent each, compared to the global average of 7 tons per person.
Although the government has pledged net zero emissions by 2050, critics complain that immediate action is not being taken. Researcher Emilio La Rovere, one of the coordinators of a report from 2013, said: "if nothing is done to restrict post-2020 emissions, Brazil may emit 2.5 billion tons of carbon dioxide as early as 2030. To give you an idea, the number exceeds the total for 2005, when emissions totaled around 2 billion tons."
Agriculture
Cattle
In 2012, Brazil had the second largest number of cattle in the world, with 205 million head. Cows are ruminants that emit greenhouse gases such as methane and nitrous oxide.
Deforestation
Trees are cut down to create fields for cattle and soya. Deforestation peaked in 2004, then decreased until the early 2010s. Since then, deforestation has tended to increase through 2020.
Fossil fuels
The largest single emitter in the energy sector is oil products used as fuel for transport in Brazil, but some natural gas and coal is burnt by the electricity sector in Brazil. In 2016/17, coal-fired power stations in Brazil received over 1 billion reals in subsidies. In the Convention on Biological Diversity, Brazil committed to phasing out environmentally harmful subsidies by 2020, but the government said in 2022 that coal power would be subsidized until 2040.
Impacts on the natural environment
Temperature and weather changes
According to José Marengo, of the National Institute for Space Research, recent studies show that, with the exception of stretches of the coast of Chile, where there has been a slight cooling in recent decades, in all other areas of South America, forecasts indicate an increase in temperature.
The Amazon has a prominent role in regulating the climate throughout Brazil and other regions in South America. Its forest is a major carbon sink and is essential for the formation of the rains that irrigate much of the country. According to Marengo et al., 30% to 50% of the rainfall in the Amazon Basin originates in the forest itself through evaporation. "In addition, the humidity originated in the Amazon Basin is carried by the winds to other parts of the continent and is considered important in the formation of precipitation in regions distant from the Amazon itself." Naturally, if the forest disappears, the rains will disappear. A vicious circle is created in which if deforestation exceeds a certain critical level, estimated at losses of 40%, the forest will be unable to generate enough rain to maintain itself: the less forest, the less precipitation, and the less precipitation, the less forest. About 19% of the Amazon forest has already been lost, and recent studies indicate that it is close to passing the critical point, beyond which its degradation will become irreversible. In addition to the problems in the Amazon, all other national biomes – the Cerrado, the Semi-Arid, the Pantanal, the Atlantic Forest and the Pampa – also suffer important effects, most of them with an increasing tendency, contributing to amplify the cascading effects.
Another important part of the Brazilian rains comes from the circulation of ocean moisture. Global warming also has an impact on ocean currents that influence the Brazilian climate, and the winds that carry the humidity that reaches Brazil are having their patterns modified, with the effect of reducing the level of atmospheric humidity and disturbing the formation of clouds, reducing precipitation. Reducing rainfall, in turn, can dry underground aquifers. These combined factors mean, in total, a generalized reduction in the availability of water and drier environments in most of the nation. In some regions, however, due to different mechanisms, rainfall is expected to increase, also bringing adverse effects. According to the PBMC, "the change with the greatest impact will be a change in rainfall patterns. Research shows that in the south and southeast, regions that suffer from floods and landslides, rains will become stronger and more frequent. In the northeast, the trend is the opposite.
Projections of the First National Assessment Report on Climate Change (2012)
In the executive summary of the 1st PBMC Report, the limitations of the study are highlighted. Because some projections were made based on incomplete data, there is some uncertainty about the conclusions. Despite this,
"In general, the results of the models managed to capture the behavior of the present climate very well and, thus, despite the uncertainties, the projections of future climate changes throughout the 21st century are plausible. Therefore, such projections constitute innovative and valuable information both for the purpose of mitigation, as well as the planning of adaptation and minimization of impacts and vulnerability actions with the set of inhabiting society in different Brazilian biomes. Taking into account the different projections that imply potential impacts on natural and human systems (socioeconomic and environmental), it is already possible to analyze the expected impacts of climate change in the various sectors of Brazil, and the planning and decision making to define adaptation strategies and mitigation policies."
For the Semi-Arid-Caatinga, an increase of up to 4.5 °C in air temperature and a reduction of up to 50% in rainfall are predicted. The environment, naturally very dry and with sparse vegetation, can partially become desert. For the Cerrado the disturbances would be similar, with an increase in temperature of up to 5.5 °C and a decrease of up to 45% in rainfall. The Cerrado today concentrates most of the agricultural activities in Brazil. The Pantanal would also be very affected, with up to a 4.5 °C increase and up to 45% less rain. In the Atlantic Forest, the climate would stay up to 3 °C warmer and up to 30% rainier. For Pampa, there would be up to 3 °C increase in temperature averages, and rains up to 40% above normal.
Not only will precipitation totals change, it may start to occur in more erratic and violent patterns, with more intense and prolonged droughts and more severe and frequent flooding episodes, varying in different regions. According to the report, "the scenarios point to a decrease in rainfall in the winter months across the country, as well as in the summer in eastern Amazonia and the Northeast. [...] In contrast, the country could experience an increase in the frequency and intensity of intense rain in the subtropical region (South region and part of the Southeast) and in the extreme west of the Amazon." Changes in the levels and availability of groundwater are also foreseen.
Sea level rise
Measurements on the coast of São Paulo indicate that sea level has risen 30 cm in the last century, surpassing the world average, and there are already many signs of coastal erosion, groundwater is gradually salted, the hangovers become higher, causing damage to the infrastructure of coastal cities. Twenty beaches are in danger of disappearing. In Recife, the famous Boa Viagem beach lost some sections swallowed by the sea, and Olinda lost 59% of its strip of sand between 1995 and 2010.
Ecosystems
Brazil's ecosystems will be impacted by temperature changes and rainfall changes. In the projections of the 1st Report, by the end of the 21st century, the Amazon may experience a reduction of up to 45% in rainfall, and an increase in the average temperature of up to 6 °C. This comes close to the worst scenarios foreseen by the Intergovernmental Panel on Climate Change (IPCC), which predicted important changes in most of the biome. However, the impact of deforestation was not considered in the assessment, which will certainly increase the levels of variation to some extent. The evolution of the future scenario will depend on the country's success in managing the serious threats to the biome. After a decade-long trend of reduced deforestation rates, recent years have documented a rapid increase in destruction of trees. A report estimated that if 40% of the forest disappears, droughts will increase and turn much of the forest into savanna. This will result in a drastic reduction in biodiversity and will also have a negative effect on the amount of rain Brazil can expect.
Impacts on people
Economic impacts
There are multiple impacts of climate change on basic Brazilian production systems, such as increasing existing shortages and increasing production costs. It is also expected that more and more serious natural disasters will occur. This will likely result in major problems for food supply, public health, industrial production, trade, installed infrastructure, the general quality of life of the population and national security as a whole, with the poor suffering the most serious consequences. The areas most vulnerable to major impacts are the Northeast and Southeast regions, exactly where most of the Brazilian people are concentrated, and large cities, which in general are poorly prepared to face the challenge.
Agriculture
In the agricultural sector, the impacts of climate change in Brazil would be multiple and significant. About 11 million hectares of arable land could be lost by 2030 due to warming. As global warming also produces several chemical and physical changes in the ocean, interfering with aquatic life, problems are foreseen for national fishing, both by reducing stocks and by geographic redistribution of economically valuable species.
A 2008 study, directly inspired by the work of the IPCC, especially in the Fourth Report, was produced by Embrapa focusing on agribusiness and food security. Its main conclusions are:
Global warming can jeopardize Brazilian food production, leading to losses that can reach 7.4 billion reals in 2020 and up to 14 billion in 2070;
Soy, whose explosive growth in the last 30 years has triggered an unprecedented change in the country's economic structure, is likely to be the crop most affected. In the worst-case scenario, losses could reach 40% in 2070, leading to a loss of up to 7.6 billion reals;
Coffee is expected to lose up to 33% of the low-risk area in the main producing states, São Paulo and Minas Gerais, although it may have gains in the south of the country;
Corn, rice, beans, cotton and sunflower will suffer a strong reduction of low risk area in the Northeast, with significant loss of production.
Cassava will have a general gain in low risk area, but will likely suffer severe losses in the Northeast;
Sugarcane, one of the few favored crops, could double its area in the coming decades.
"From one of the villains of global warming (See note:), agriculture can become a victim. Throughout the world, warming will only benefit agriculture practiced in high-latitude regions. ... The configuration of Brazilian agricultural production, as it is known today, can change significantly due to global warming. ... Regions that are currently the largest grain producers may not be able to plant well before the end of the century. ... Despite the losses, agriculture can be part of the solution to the problem. A more appropriate use of the soil, with the adoption, for example, of agropastoral, agro-forestry and no-tillage systems, besides reducing the use of fertilizers, can prevent new deforestation, increase the capture of carbon dioxide from the atmosphere and recover the soil. Some new techniques for growing rice and raising livestock are also being tested to decrease methane emissions".
In 2022, a study found that 28% of the agricultural land in Brazil is no longer climatically optimal for agriculture due to climate change and to change in local climate as a result of deforestation. The number will go up to 51% by 2030 and 74% by 2060 if the change in climate will continue in the same way.
Cattle Industry
The 2012 drought in the Northeast affected more than ten million people and generated a loss of more than R$16 billion. In 2013, the phenomenon was repeated with even greater intensity, being considered by the UN the worst of the last 50 years, leaving 1,200 municipalities in a state of emergency. In Paraíba alone, 360,000 heads of cattle died.
Energy sector
Climate change in Brazil may also result in an energy crisis, since the largest percentage of national electricity is generated by hydroelectric plants. It is expected that there will be an important drop in the flow of most of the great national hydrographic basins. According to the Climate Observatory,
"The result is dramatic for those who think that the Southeast of Brazil has suffered enough from lack of water and the threat of energy rationing in the last three years: in the best scenario, several rivers in Minas Gerais, São Paulo, Goiás, Tocantins, Bahia and Pará will have flow reductions of 10% to 30%. Transposed to hydroelectric plants, the flow data presents a challenge for the energy sector in Brazil: the most important plants in the country – Furnas, Itaipu, Sobradinho and Tucuruí – would have flow reductions of 38% to 57% in the worst case scenario. In the Amazon, a region elected by the government as the new frontier for hydroelectricity in the country, the falls would also be significant, as the Climate Observatory said in April: the flow of Belo Monte would fall from 25% to 55%, that of Santo Antônio, from 40% to 65%, and that of the planned plant in São Luís do Tapajós, from 20% to 30%. With the exception of São Luís, most of the new plants in the Amazon are run-of-river, that is, they do not have a large reservoir. This means that its capacity factor, that is, the amount of constant energy generated throughout the year, is reduced, since the flow of Amazonian rivers varies enormously between the dry and the rainy seasons. Belo Monte, for example, has a capacity factor of around 40%, which, reduced by half, would give the R$30 billion hydroelectric power plant a smaller capacity factor than that of wind farms – at which Brazilian energy planners and President Dilma Rousseff turn up their noses, as these plants are not capable of generating 'firm power' in periods without wind. In total, hydroelectric generation falls from 8% to 20% in the country. ...
"The researchers' analysis shows that, in all the scenarios analyzed, there is a drop in the flow of the main Brazilian hydrographic basins, which pushes the electrical system into a situation of structural imbalance: the system is unable to meet demand, causing load shedding – that is blackouts. Without measures to cut emissions, in the worst case scenario, the flow of reservoirs drops by 30% and the risk of deficit in some years approaches 100% – the margin considered 'safe' by the government to prevent blackouts is 5%. In the best scenario, the drop in flow from hydroelectric plants reaches 10%, and the risk of deficit, 60% in some years. The cost of operating the system, which takes into account even the activation of thermal plants, rises eight times in the best scenario and 16.7 times in the worst ".
This would have negative consequences in other ways, as it would encourage the use of coal and natural gas-fired power plants, which are major emitters of greenhouse gases.
Health impacts
Heat waves
A special alert was given in a 2015 report for the increased risk of extreme heat waves, mainly affecting the elderly and the North and Northeast regions, further aggravating pre-existing diseases, such as respiratory problems. José Feres, from the Institute of Applied Economic Research, said that Brazil's ageing population is particularly at risk. The report also pointed to the tendency towards an increase in endemic infectious diseases such as malaria, dengue and leptospirosis, the tendency towards an increase in the problems of conservation of the road network, and showed concern about Brazil's little preparation in the management of climatic disasters and the scarce information available on the future impacts of rising sea levels.
Floods and landslides
In the city of São Paulo alone, where rain is forecast to increase, flooding causes a loss of 762 million reals per year. In the floods and landslides in Rio de Janeiro in 2011, the greatest natural tragedy ever experienced in the country, 906 people died, 400 were reported missing, 30,000 had to leave their homes, 770 hillsides had their stability compromised, and will need to be reconsolidated at an estimated cost of 3.3 billion reals. The loss for companies reached R$470 million. In 2011, according to the UN calculation, floods throughout Brazil totaled 10 billion reals in material losses and claimed more than a thousand lives, in addition to leaving homeless crowds and producing disorders of various orders that will take years to be balanced.
A report from 2013 found that the coastal region, where the vast majority of the country's population lives, should receive special attention, in view of a likely increase in floods, landslides, severe weather, coastal erosion, rising sea levels and other natural disasters caused by warming: "It is no longer possible, as a Brazilian, to accept more disasters that kill more than a thousand Brazilians at once. Protective and preventive measures have to be taken urgently. Extreme events are happening more often. The population that is not prepared, will suffer from it."
Impacts on housing
Researcher Andrea Santos, executive secretary of PBMC, warned in 2013 about the likely impact on megacities such as Rio and São Paulo, stating that the current infrastructure, especially in transport and urban mobility, was not designed to face rising temperatures and more intense rainfall.
"Between 1991 and 2012, more than half of the Brazilian population had their lives affected by extreme weather events. Droughts, floods and landslides affected 127 million people. The number of records has grown 40% in the past decade compared to the previous one, according to the Brazilian Atlas of Natural Disasters. Recent tragedies include that of Santa Catarina, in 2008, and that of serra fluminense, in 2011. This year, a fifth of the country's municipalities entered an emergency or public calamity situation. Global warming, combined with urban expansion and the development problems that Brazil already has, allows us to project a gloomy scenario for this century, in which the number of people affected and the cost of tragedies for the economy only increase. And no one will be spared."
Impacts on indigenous peoples
Indigenous people consist of 40 million of the Latin American-Caribbean populations. They populate most of the rural poor areas in countries such as Ecuador, Brazil, Peru and Paraguay. This makes these populations extremely susceptible to threats of climate change due to socioeconomic, geographic, and political factors.
Mitigation and adaptation
Policies and legislation
Suzana Bustamante, one of the coordinators of Working Group 3 of the 5th IPCC Report, considers that the greatest threats hanging over Brazil stem from the expected reduction in rainfall in most of the area of food production and capture for hydroelectric and consumption, the country's strategy, both adaptive and mitigating, of investing in reducing deforestation must be a priority for the country, as forests are major producers and conservators of water resources, in addition to all the other essential environmental services they provide and all the biodiversity they harbor. Brazil is the most biodiverse country in the world, an invaluable wealth that is at great risk and is suffering continuous losses.
Jair Bolsonaro has said that foreigners should stop complaining about fires in the Amazon, and the country's environmental policies and in 2020 accused them of a "brutal disinformation campaign." In 2021, Brazil announced that it will not block carbon market agreements in COP26 what has significant importance.
Brazil 2040: scenarios and alternatives for adapting to climate change
Published in 2015 by the Secretariat for Sustainable Development of the Secretariat for Strategic Affairs of the Presidency of the Republic, the Brazil 2040 report was considered by the Climate Observatory to be the largest study carried out to date on climate change in Brazil. It had the main objective of giving guidance to the government for the establishment of a more coherent and solid climate policy, focusing on the areas of health, water resources, energy, agriculture and infrastructure (coastal and transport), and using two theoretical models that were used by the IPCC. The report obtained results that are broadly consistent with other studies, pointing to a country that is mostly drier and warmer in the future.
Brazil 2040 emphasized the country's lack of preparedness to face the expected climatic disasters that are expected to worsen with the progress of climate change, such as major droughts and floods, storms, rising levels sea and landslides caused by torrential rains. It was also identified that despite the numerous mitigation and adaptation programs already approved by the Union, States and Municipalities, they typically do not leave the paper, or produce timid or marginal results.
Analyzing the case of the emergency support structure in the city of Rio de Janeiro, it was pointed out that the majority of the resources for assisting the population (hospitals, military and police facilities, fire departments, etc.) are located in medium or high areas. Vulnerability to natural disasters, along rivers and canals or in low-lying regions, which can easily flood, or at the seaside, subject to rising levels and coastal storms, and can be compromised even in small climatic events, harming their functionality and increasing impacts on society. The majority of water and sewage treatment plants are located in the same regions, as well as many points on the main highways and streets, including some major road junctions, offering increased risks in the event of a disaster in terms of sanitation, supply and transportation of flagellates. Even worse is the situation of transportation by the subway, which is mostly in regions of high vulnerability. Citing the threat of sea level rise, it was pointed out that there is real estate value in the order of 124 billion reals located in areas of high vulnerability, and 2.7 trillion reals in areas of medium vulnerability. In the case of the city of Santos, most of the urban area is in an area of high vulnerability and many in areas of very high vulnerability, which puts the entire city at high risk, with more than R$100 billion in real estate values in regions of high vulnerability. The report stated that these examples can be extrapolated to many other regions of Brazil with a high demographic density, since most cities are in low coastal regions or next to rivers, lakes and fragile hillsides. Port areas also present increased risks of deterioration or destruction of structures, flooding, silting of channels and estuarine bars and others, and a large part of Brazil's national and international trade depends on them.
Suzana Kahn Ribeiro, president of the Scientific Committee of the Brazilian Panel on Climate Change, has a very similar opinion: "Brazil needs to find a direction, define what it wants to be when it grows up. ... Brazil is showing mixed signals all the time. We reduce IPI tax on car so that everyone gets bottled up in traffic. We are experiencing a blackout of climate coordination ". André Ferretti, general coordinator of the Climate Observatory, says the same:
"Today we have trillions of resources to be invested in infrastructure, plans to expand energy generation mainly from fossil sources (about 70% of the country's investments), annual harvest plans and industry incentives, without any connection with the logic of development. low carbon. We have a set of disconnected climate policies, without coordination and that do not even have their potential positive impacts monitored; and the Climate Fund is completely threatened and with limited resources. ... The great message of the IPCC's fifth report is that the situation is increasingly critical, and that if nothing or very little is done, we will enter a very dangerous path. The window of opportunity for us to prevent the collapse of the climate system is narrow."
Even some sectors of the government agree that there are problems in this area: Carlos Nobre, secretary of Research and Development Policies and Programs at the Ministry of Science, Technology and Innovation, said that "the Ministry of Science and Technology is playing its part, investing in research development and knowledge generation, but there is still a lack of integration between research and policy making."
Another of Brazil's latest Nationally Determined Contribution to the Paris Agreement aims to reduce greenhouse gas emissions by 48 percent by 2025 and 53 percent by 2030. President Luiz Inácio “Lula” da Silva has prioritized combating climate change, reestablishing the Amazon Fund to prevent deforestation and promote sustainable use of the Amazon. The United States Agency for International Development supports these efforts through initiatives focusing on biodiversity conservation, sustainable management of protected areas, and innovative financial instruments for nature-based solutions.
USAID’s Climate Change Program: Objectives and Results
USAID's climate change program in Brazil focuses on leveraging resources from the private sector for biodiversity conservation and improving local livelihoods. Key results from 2022 include avoiding more than 23 million metric tons of CO2 equivalent GHG emissions, strengthening the management of 117 Protected Areas covering 47.9 million hectares, and reducing deforestation rates in USAID-supported areas.
Society and culture
Activism
Calculations in 2021 showed that, for giving the world a 50% chance of avoiding a temperature rise of 2 degrees or more, Brazil should increase its climate commitments by 90%. For a 95% chance, it should increase the commitments by 165%. For giving a 50% chance of staying below 1.5 degrees Brazil, should increase its commitments by 170%.
A report from 2013 aimed to dispel some ingrained myths that represent major obstacles to the general acceptance of mitigation projects, such as that progress and nature conservation are opposed, or that the consequence of reducing emissions will be economic recession.
| Physical sciences | Climate change | Earth science |
58446217 | https://en.wikipedia.org/wiki/Calcium%20cycle | Calcium cycle | The calcium cycle is a transfer of calcium between dissolved and solid phases. There is a continuous supply of calcium ions into waterways from rocks, organisms, and soils. Calcium ions are consumed and removed from aqueous environments as they react to form insoluble structures such as calcium carbonate and calcium silicate, which can deposit to form sediments or the exoskeletons of organisms. Calcium ions can also be utilized biologically, as calcium is essential to biological functions such as the production of bones and teeth or cellular function. The calcium cycle is a common thread between terrestrial, marine, geological, and biological processes. Calcium moves through these different media as it cycles throughout the Earth. The marine calcium cycle is affected by changing atmospheric carbon dioxide due to ocean acidification.
Calcium weathering and inputs to seawater
Calcium is stored in geologic reservoirs, most commonly in the form of calcium carbonate or as calcium silicate. Calcium-containing rocks include calcite, dolomite, phosphate, and gypsum. Rocks slowly dissolve by physical and chemical processes, carrying calcium ions into rivers and oceans. Calcium ions (Ca2+) and magnesium ions (Mg2+) have the same charge (+2) and similar sizes, so they react similarly and are able to substitute for each other in some minerals, such as carbonates. Ca2+-containing minerals are often more easily weathered than Mg2+ minerals, so Ca2+ is often more enriched in waterways than Mg2+. Rivers containing more dissolved Ca2+ are generally considered more alkaline.
Calcium is one of the most common elements found in seawater. Inputs of dissolved calcium (Ca2+) to the ocean include the weathering of calcium sulfate, calcium silicate, and calcium carbonate, basalt-seawater reaction, and dolomitization.
Biogenic calcium carbonate and the biological pump
Biogenic calcium carbonate is formed when marine organisms, such as coccolithophores, corals, pteropods, and other mollusks transform calcium ions and bicarbonate into shells and exoskeletons of calcite or aragonite, both forms of calcium carbonate. This is the dominant sink for dissolved calcium in the ocean. Dead organisms sink to the bottom of the ocean, depositing layers of shell which over time cement to form limestone. This is the origin of both marine and terrestrial limestone.
Calcium precipitates into calcium carbonate according to the following equation:
Ca2+ + 2HCO3− → CO2+ H2O + CaCO3
The relationship between dissolved calcium and calcium carbonate is affected greatly by the levels of carbon dioxide (CO2) in the atmosphere.
Increased carbon dioxide leads to more bicarbonate in the ocean according to the following equation:
CO2 + CO32− + H2O → 2HCO3−
With ocean acidification, inputs of carbon dioxide promote the dissolution of calcium carbonate and harm marine organisms dependent on their protective calcite or aragonite shells. The solubility of calcium carbonate increases with pressure and carbon dioxide and decreases with temperature. Thus, calcium carbonate is more soluble in deep waters than surface waters due to higher pressure and lower temperature. As a result, precipitation of calcium carbonate is more common in shallower oceans. The depth at which the rate of calcite dissolution equals the rate of calcite precipitation is known as calcite compensation depth.
Changes in global climate and the calcium cycle
Ocean acidity due to carbon dioxide has already increased by 25% since the industrial revolution. As carbon dioxide emissions continually increase and accumulate, this will negatively affect the lives of many marine ecosystems. The calcium carbonate used to form many marine organisms' exoskeletons will begin to break down, leaving these animals vulnerable and unable to live in their habitats. This ultimately has a flow on effect to predators, further affecting the function of many food webs globally.
Changes in calcium concentrations over geologic time
Calcium stable isotopes have been used to study inputs and outputs of dissolved calcium in marine environments. For example, one study found that calcium levels have decreased between 25 and 50 percent over a 40 million year timespan, suggesting that dissolved Ca2+outputs have exceeded its inputs. The isotope Calcium-44 can help to indicate variations in calcium carbonate over long timespans and help explain variants in global temperature. Declines in the isotope Calcium-44 usually correlate with periods of cooling, as dissolution of calcium carbonate typically signifies a decrease in temperature. Thus, Calcium isotopes correlate with Earth's climate over long periods of time.
Human/animal use of calcium
Being an essential element, calcium is obtained through dietary sources, the majority of which comes from dairy products. The most significant mechanisms controlling calcium use within the body are intestinal absorption, renal filtration, renal reabsorption and bone turnover, which are controlled predominantly by hormones and their corresponding receptors in the gut, kidneys and bones respectively. This allows for calcium use throughout the body, namely in bone growth, cellular signalling, blood clotting, muscle contraction and neuron function.
Calcium is one of the essential components of bone, contributing to its strength and structure in addition to being the main site at which it is stored within the body. Within the muscles, its primary use is to enable contractions. Muscle cells draw calcium from the blood, allowing it to bind with troponin, a component of the muscle fibre that signals for a contraction by moving actin and myosin. After a contraction, calcium dissipates and the filaments move back to a resting state before the release of more calcium for the next contraction. Furthermore, calcium plays a significant role in allowing nerve impulses to be transmitted between neurons. The release of calcium ions from voltage gated ion channels signals for the release of neurotransmitters into the synapse. This allows for the depolarisation of a neuron, thus transmitting the signal to the next neuron where this process is once again repeated. Without the presence of calcium ions, the release of neurotransmitters would not occur, preventing signals from being sent and hindering body processes.
Negative feedback mechanisms are implemented in order to control calcium levels. When low calcium levels are detected in the body, the parathyroid releases parathyroid hormone (PTH) which travels through the bloodstream to the bones and kidneys. In the bones, the presence of PTH stimulates osteoclasts. These cells break down bone to release calcium into the bloodstream where it can be used by the rest of the body in the above processes. In the kidneys, PTH stimulates re-absorption of calcium so it in not lost from the body through urine and returned to the bloodstream instead. Lastly, PTH acts on the intestines by indirectly promoting enzymes that activate vitamin D, a signal for the intestines to absorb more calcium, further increasing blood calcium levels. This will continue until the body releases too much calcium into the bloodstream. Excess calcium then promotes the release of calcitonin from the thyroid gland, effectively reversing the process of PTH. Osteoclast activity is stopped and osteoblasts take over, utilising the excess calcium in the bloodstream to form new bone. Calcium re-absorption in the kidney is prevented, allowing the excretion of excess calcium through the urine. Through these hormonal mechanisms, calcium homeostasis is maintained within the body.
Calcium in plants and soil
Calcium is an essential component of soil. When deposited in the form of lime, it cannot be used by plants. To combat this, carbon dioxide produced by plants reacts with water in the environment to produce carbonic acid. Carbonic acid is then able to dissolve limestone, enabling the release of calcium ions. This reaction is more readily available with smaller particles of limestone than it is with large pieces of rock due to the increased surface area. When lime is leached into soil, calcium levels inevitably increase, both stabilising pH and enabling calcium to mix with water to form Ca2+ ions, thus making it soluble and accessible to plants to be absorbed and utilised by the root system. The calcium ions travel up the xylem of the plant alongside water to reach the leaves. The plant can utilise this calcium in the form of calcium pectate to stabilise cell walls and provide rigidity. Calcium is also used by plant enzymes to signal growth and coordinate life-promoting processes. Additionally, the release of calcium ions enables microorganisms to access phosphorus and other micro nutrients with greater ease, improving the soil ecosystem drastically thus indirectly promoting plant growth and nutrition.
Inevitable plant and animal death results in the return of calcium contained within the organism back into the soil to be utilised by other plants. Decomposing organisms break them down, returning the calcium back into the soil and enabling the cycling of calcium to continue. Additionally, these animals and plants are eaten by other animals, similarly continuing the cycle. It is however important to note the modern introduction of calcium into the soil by humans (through fertilisers and other horticultural products) has resulted in a higher concentration of calcium contained within soil.
Industrial uses of calcium and its impact on the calcium cycle
The naturally occurring calcium cycle has been altered by human intervention. Calcium is predominantly extracted from limestone deposits to be utilised by many industrial processes. Purification of iron ore and aluminium, replacing asbestos brake linings and some coatings for electric cables, are some of these major uses of calcium. Furthermore, calcium is used within the household to maintain alkaline pH of swimming pools, counteracting acidic disinfectants and in the food production industry to produce bicarbonate soda, some wines and dough.
With its widespread uses, a large volume of calcium must be obtained from mines and quarries to supply the high demand. As more limestone and water is removed from mines, underground stores of rock are often weakened making the ground more susceptible to sink holes. Sinkholes and mining both affect the presence of groundwater, potentially leading to a lower water table or altered pathways of flowing water. This may affect local ecosystems or farmland as the water supply is restricted. Additionally, the water that is released from mining areas will have higher concentrations of dissolved calcium. This can either be released into oceans or absorbed by the soil. Whilst not always detrimental, it alters the natural calcium cycle which may have flow-on effects for ecosystems. Furthermore, water being pumped from mines increases the danger of downstream flooding whilst simultaneously decreasing the volume on water in upstream reservoirs such as marshes, ponds of wetlands It is however important to note than limestone mining is comparatively less damaging than other mining process, with potential to restore the environment after the mine is no longer in use
The importance of the calcium cycle and future predictions
The calcium cycle links ionic and non ionic calcium together in both marine and terrestrial environments and is essential for the functioning of all living organisms. In animals, calcium enables neurons to transmit signals by opening voltage gated channels that allow neurotransmitters to reach the next cell, bone formation and development and kidney function, whilst being maintained by hormones that ensure calcium homeostasis is reached. In plants, calcium promotes enzyme activity and ensures cell wall function, providing stability to plants. It also enables crustaceans to form shells and corals to exist, as calcium provides structure, rigidity and strength to structures when complexed (combined) to other atoms. Without its presence in the environment, many life-preserving processes would not exist. In the modern context, calcium also enables many industrial processes to occur, promoting further technological developments.
With its close relation to the carbon cycle and the effects of greenhouse gasses, both calcium and carbon cycles are predicted to change in the coming years. Tracking calcium isotopes enables the prediction of environmental changes, with many sources suggesting increasing temperatures in both the atmosphere and marine environment. As a result, this will drastically alter the breakdown of rock, the pH of oceans and waterways and thus calcium sedimentation, hosting an array of implications on the calcium cycle.
Due to the complex interactions of calcium with many facets of life, the effects of altered environmental conditions are unlikely to be known until they occur. Predictions can however be tentatively made, based upon evidence-based research. Increasing carbon dioxide levels and decreasing ocean pH will alter calcium solubility, preventing corals and shelled organisms from developing their calcium-based exoskeletons, thus making them vulnerable or unable to survive.
| Physical sciences | Earth science basics: General | Earth science |
58458383 | https://en.wikipedia.org/wiki/Ecosystem%20collapse | Ecosystem collapse | An ecosystem, short for ecological system, is defined as a collection of interacting organisms within a biophysical environment. Ecosystems are never static, and are continually subject to both stabilizing and destabilizing processes. Stabilizing processes allow ecosystems to adequately respond to destabilizing changes, or perturbations, in ecological conditions, or to recover from degradation induced by them: yet, if destabilizing processes become strong enough or fast enough to cross a critical threshold within that ecosystem, often described as an ecological 'tipping point', then an ecosystem collapse (sometimes also termed ecological collapse). occurs.
Ecosystem collapse does not mean total disappearance of life from the area, but it does result in the loss of the original ecosystem's defining characteristics, typically including the ecosystem services it may have provided. Collapse of an ecosystem is effectively irreversible more often than not, and even if the reversal is possible, it tends to be slow and difficult. Ecosystems with low resilience may collapse even during a comparatively stable time, which then typically leads to their replacement with a more resilient system in the biosphere. However, even resilient ecosystems may disappear during the times of rapid environmental change, and study of the fossil record was able to identify how certain ecosystems went through a collapse, such as with the Carboniferous rainforest collapse or the collapse of Lake Baikal and Lake Hovsgol ecosystems during the Last Glacial Maximum.
Today, the ongoing Holocene extinction is caused primarily by human impact on the environment, and the greatest biodiversity loss so far had been due to habitat degradation and fragmentation, which eventually destroys entire ecosystems if left unchecked. There have been multiple notable examples of such an ecosystem collapse in the recent past, such as the collapse of the Atlantic northwest cod fishery. More are likely to occur without a change in course, since estimates show that 87% of oceans and 77% of the land surface have been altered by humanity, with 30% of global land area is degraded and a global decline in ecosystem resilience. Deforestation of the Amazon rainforest is the most dramatic example of a massive, continuous ecosystem and a biodiversity hotspot being under the immediate threat from habitat destruction through logging, and the less-visible, yet ever-growing and persistent threat from climate change.
Biological conservation can help to preserve threatened species and threatened ecosystems alike. However, time is of the essence. Just as interventions to preserve a species have to occur before it falls below viable population limits, at which point an extinction debt occurs regardless of what comes after, efforts to protect ecosystems must occur in response to early warning signals, before the tipping point to a regime shift is crossed. Further, there is a substantial gap between the extent of scientific knowledge how extinctions occur, and the knowledge about how ecosystems collapse. While there have been efforts to create objective criteria used to determine when an ecosystem is at risk of collapsing, they are comparatively recent, and are not yet as comprehensive. While the IUCN Red List of threatened species has existed for decades, the IUCN Red List of Ecosystems has only been in development since 2008.
Definition
Ecosystem collapse has been defined as a "transformation of identity, loss of defining features, and replacement by a novel ecosystem", and involves the loss of "defining biotic or abiotic features", including the ability to sustain the species which used to be associated with that ecosystem. According to another definition, it is "a change from a baseline state beyond the point where an ecosystem has lost key defining features and functions, and is characterised by declining spatial extent, increased environmental degradation, decreases in, or loss of, key species, disruption of biotic processes, and ultimately loss of ecosystem services and functions". Ecosystem collapse has also been described as "an analogue of species extinction", and in many cases, it is irreversible, with a new ecosystem appearing instead, which may retain some characteristics of the previous ecosystem, yet has agreatly altered structure and function. There are exceptions where an ecosystem can be recovered past the point of a collapse, but by definition, will always be far more difficult to reverse than allowing a disturbed yet functioning ecosystem to recover, requiring active intervention and/or a prolonged period of time even if it can be reversed.
Drivers
While collapse events can occur naturally with disturbances to an ecosystem—through fires, landslides, flooding, severe weather events, disease, or species invasion—there has been a noticeable increase in human-caused disturbances over the past fifty years. The combination of environmental change and the presence of human activity is increasingly detrimental to ecosystems of all types, as our unrestricted actions often increase the risk of abrupt (and potentially irreversible) changes post-disturbance; when a system would otherwise have been able to recover.
Some behaviors that induce transformation are: human intervention in the balance of local diversity (through introduction of new species or overexploitation), alterations in the chemical balance of environments through pollution, modifications of local climate or weather with anthropogenic climate change, and habitat destruction or fragmentation in terrestrial/marine systems. For instance, overgrazing was found to cause land degradation, specifically in Southern Europe, which is another driver of ecological collapse and natural landscape loss. Proper management of pastoral landscapes can mitigate risk of desertification.
Despite the strong empirical evidence and highly visible collapse-inducing disturbances, anticipating collapse is a complex problem. The collapse can happen when the ecosystem's distribution decreases below a minimal sustainable size, or when key biotic processes and features disappear due to environmental degradation or disruption of biotic interactions. These different pathways to collapse can be used as criteria for estimating the risk of ecosystem collapse. Although states of ecosystem collapse are often defined quantitatively, few studies adequately describe transitions from pristine or original state towards collapse.
Geological record
In another example, 2004 research demonstrated how during the Last Glacial Maximum (LGM), alternations in the environment and climate led to a collapse of Lake Baikal and Lake Hovsgol ecosystems, which then drove species evolution. The collapse of Hovsgol's ecosystem during the LGM brought forth a new ecosystem, with limited biodiversity in species and low levels of endemism, in Hovsgol during the Holocene. That research also shows how ecosystem collapse during LGM in Lake Hovsgol led to higher levels of diversity and higher levels of endemism as a byproduct of subsequent evolution.
In the Carboniferous period, coal forests, great tropical wetlands, extended over much of Euramerica (Europe and America). This land supported towering lycopsids which fragmented and collapsed abruptly. The collapse of the rainforests during the Carboniferous has been attributed to multiple causes, including climate change and volcanism. Specifically, at this time climate became cooler and drier, conditions that are not favourable to the growth of rainforests and much of the biodiversity within them. The sudden collapse in the terrestrial environment made many large vascular plants, giant arthropods, and diverse amphibians to go extinct, allowing seed-bearing plants and amniotes to take over (but smaller relatives of the affected ones survived also).
Historic examples of collapsed ecosystems
The Rapa Nui subtropical broadleaf forests in Easter Island, formerly dominated by an endemic Palm, are considered collapsed due to the combined effects of overexplotaition, climate change and introduced exotic rats.
The Aral Sea was an endorheic lake between Kazakhstan and Uzbekistan. It was once considered one of the largest lakes in the world but has been shrinking since the 1960s after the rivers that fed it were diverted for large scale irrigation. By 1997, it had declined to 10% of its original size, splitting into much smaller hypersaline lakes, while dried areas have transformed into desert steppes.
The regime shift in the northern Benguela upwelling ecosystem is considered an example of ecosystem collapse in open marine environments. Prior to the 1970s sardines were the dominant vertebrate consumers, but overfishing and two adverse climatic events (Benguela Niño in 1974 and 1984) lead to an impoverished ecosystem state with high biomass of jellyfish and pelagic goby.
Another notable example is the collapse of the Grand Banks cod in the early 1990s, when overfishing reduced fish populations to 1% of their historical levels.
Contemporary risk
There are two tools commonly used together to assess risks to ecosystems and biodiversity: generic risk assessment protocols and stochastic simulation models. The most notable of the two tactics is risk assessment protocol, particularly because of the IUCN Red List of Ecosystems (RLE), which is widely applicable to many ecosystems even in data-poor circumstances. However, because using this tool is essentially comparing systems to a list of criteria, it is often limited in its ability to look at ecosystem decline holistically; and is thus often used in conjunction with simulation models that consider more aspects of decline such as ecosystem dynamics, future threats, and social-ecological relationships.
The IUCN RLE is a global standard that was developed to assess threats to various ecosystems on local, regional, national, and global scales, as well as to prompt conservation efforts in the face of the unparalleled decline of natural systems in the last decade. And though this effort is still in the earlier stages of implementation, the IUCN has a goal to assess the risk of collapse for all of the world's ecosystems by 2025. The concept of ecosystem collapse is used in the framework to establish categories of risk for ecosystems, with the category Collapsed used as the end-point of risk assessment. Other categories of threat (Vulnerable, Endangered and Critically Endangered) are defined in terms of the probability or risk of collapse. A paper by Bland et al. suggests four aspects for defining ecosystem collapse in risk assessments:
qualitatively defining initial and collapsed states
describing collapse and recovery transitions
identifying and selecting indicators of collapse
setting quantitative collapse thresholds.
Early detection and monitoring
Scientists can predict tipping points for ecosystem collapse. The most frequently used model for predicting food web collapse is called R50, which is a reliable measurement model for food web robustness. However, there are others: i.e. marine ecosystem assessments can use RAM Legacy Stock Assessment Database. In one example, 154 different marine fish species were studied to establish the relationship between pressures on fish populations such as overfishing and climate change, these populations; traits like growth rate, and the risk of ecosystem collapse.
The measurement of "critical slowing down" (CSD) is one approach for developing early warning signals for a potential or likely onset of approaching collapse. It refers to increasingly slow recovery from perturbations.
In 2020, one paper suggested that once a 'point of no return' is reached, breakdowns do not occur gradually but rapidly and that the Amazon rainforest could shift to a savannah-type mixture of trees and grass within 50 years and the Caribbean coral reefs could collapse within 15 years once a state of collapse has been reached. Another indicated that large ecosystem disruptions will occur earlier under more intense climate change: under the high-emissions RCP8.5 scenario, ecosystems in the tropical oceans would be the first to experience abrupt disruption before 2030, with tropical forests and polar environments following by 2050. In total, 15% of ecological assemblages would have over 20% of their species abruptly disrupted if as warming eventually reaches ; in contrast, this would happen to fewer than 2% if the warming were to stay below .
Rainforest collapse
Rainforest collapse refers to the actual past and theoretical future ecological collapse of rainforests. It may involve habitat fragmentation to the point where little rainforest biome is left, and rainforest species only survive in isolated refugia. Habitat fragmentation can be caused by roads. When humans start to cut down the trees for logging, secondary roads are created that will go unused after its primary use. Once abandoned, the plants of the rainforest will find it difficult to grow back in that area. Forest fragmentation also opens the path for illegal hunting. Species have a hard time finding a new place to settle in these fragments causing ecological collapse. This leads to extinction of many animals in the rainforest.
A classic pattern of forest fragmentation is occurring in many rainforests including those of the Amazon, specifically a 'fishbone' pattern formed by the development of roads into the forest. This is of great concern, not only because of the loss of a biome with many untapped resources and wholesale death of living organisms, but also because plant and animal species extinction is known to correlate with habitat fragmentation.
In the year 2022, research found that more than three-quarters of the Amazon rainforest has been losing resilience due to deforestation and climate change since the early 2000s as measured by recovery-time from short-term perturbations (the critical slowing down), reinforcing the theory that it is approaching a critical transition. Another study from 2022 found that tropical, arid and temperate forests are substantially losing resilience.
Coral reefs
A major concern for marine biologists is the collapse of coral reef ecosystems.). An effect of global climate change is the rising sea levels which can lead to reef drowning or coral bleaching. Human activity, such as fishing, mining, deforestation, etc., serves as a threat for coral reefs by affecting the niche of the coral reefs. For example, there is a demonstrated correlation between a loss in diversity of coral reefs by 30-60% and human activity such as sewage and/or industrial pollution.
Conservation and reversal
As of now there is still not much information on effective conservation or reversal methods for ecosystem collapse. Rather, there has been increased focus on the predictability of ecosystem collapse, whether it is possible, and whether it is productive to explore. This is likely because thorough studies of at-risk ecosystems are a more recent development and trend in ecological fields, so collapse dynamics are either too recent to observe or still emerging. Since studies are not yet long term, conclusions about reversibility or transformation potential are often hard to draw from newer, more focused studies.
| Biology and health sciences | Ecology | Biology |
67953981 | https://en.wikipedia.org/wiki/Windows%2011 | Windows 11 | Windows 11 is the latest major release of Microsoft's Windows NT operating system, released on October 5, 2021. It succeeded Windows 10 (2015), and is available for free for any Windows 10 devices that meet the new Windows 11 system requirements.
Windows 11 features major changes to the Windows shell influenced by the canceled Windows 10X, including a redesigned Start menu, the replacement of its "live tiles" with a separate "Widgets" panel on the taskbar, the ability to create tiled sets of windows that can be minimized and restored from the taskbar as a group, and new gaming technologies inherited from Xbox Series X and Series S such as Auto HDR and DirectStorage on compatible hardware. Internet Explorer (IE) has been replaced by the Chromium-based Microsoft Edge as the default web browser, like its predecessor, Windows 10, and Microsoft Teams is integrated into the Windows shell. Microsoft also announced plans to allow more flexibility in software that can be distributed via the Microsoft Store and to support Android apps on Windows 11 (including a partnership with Amazon to make its app store available for the purpose).
Citing security considerations, the system requirements for Windows 11 were increased over Windows 10; Microsoft only officially supports the operating system on devices using an eighth-generation Intel Core CPU or newer (with some minor exceptions), a second-generation AMD Ryzen CPU or newer, or a Qualcomm Snapdragon 850 ARM system-on-chip or newer, with UEFI and Trusted Platform Module (TPM) 2.0 supported and enabled. There are some exceptions to these requirements, however . While the OS can be installed on devices with unsupported configurations, Microsoft does not guarantee the availability of updates. Furthermore, Windows 11 completely removes support for 32-bit CPUs, including both 32-bit x86 and 32-bit ARM processors, ensuring compatibility only with 64-bit x86-64 and ARM64 processors.
Windows 11 received a mixed reception at launch. Pre-release coverage of the operating system focused on its stricter hardware requirements, with discussions over whether they were legitimately intended to improve the security of Windows, or as a ploy to upsell customers to newer devices, and over the e-waste associated with the changes. Upon release, it was praised for its improved visual design, window management, and stronger focus on security, but was criticized for various modifications to aspects of its user interface that were seen as worse than its predecessor; some were seen as an attempt to dissuade users from switching to competing applications. Additionally, some users have pointed out disadvantages such as the removal of features like the ability to move the taskbar and increased system requirements that may exclude older devices.
, Windows 11, accounting for 35% of Windows installations worldwide, is the second most popular Windows version in use, with its predecessor Windows 10 still being the most used version in virtually all countries (with Guyana being an exception, where Windows 11 is the most used), having over 2 times the market share globally. Windows 11 has an estimated 23% share of all PCs (the rest being other Windows editions and other operating systems such as macOS and Linux), and an estimated 8.6% share of all devices (including mobile, tablet and console) are running Windows 11.
To comply with the Digital Markets Act, Microsoft is allowing users in the European Economic Area to remove the Microsoft Edge browser, Microsoft Bing search engine, and advertisements to comply with users' interests.
Following the discontinuation of Windows Phone with Windows 10 Mobile in 2020, Windows 11 is the first major version of Windows NT without a companion mobile version.
Development
At the 2015 Ignite conference, Microsoft employee Jerry Nixon stated that Windows 10 would be the "last version of Windows". The operating system was considered to be a service, with new builds and updates to be released over time. PC World argued that the widely reported comment was however taken out of context, noting that the official event transcript marks it only as a segue rather than a core part of the talk. It argues that Nixon was referring to the fact that he could talk freely at the event because 10 was the last version in current development.
In October 2019, Microsoft announced "Windows 10X", a future edition of Windows 10 designed exclusively for dual-touchscreen devices such as the then-upcoming Surface Neo. It featured a modified user interface designed around context-sensitive "postures" for different screen configurations and usage scenarios, and changes such as a centered taskbar and updated Start menu without Windows 10's "live tiles". Legacy Windows applications would also be required to run in "containers" to ensure performance and power optimization. Microsoft stated that it planned to release Windows 10X devices by the end of 2020.
In May 2020, during the COVID-19 pandemic, Panos Panay, Microsoft's chief product officer for Microsoft Windows and Microsoft Office, stated that "as we continue to put customers' needs at the forefront, we need to focus on meeting customers where they are now", and announced that Windows 10X would only launch on single-screen devices at first, and that Microsoft would "continue to look for the right moment, in conjunction with our OEM partners, to bring dual-screen devices to market".
In October 2020, reports emerged that Microsoft was working on a user interface refresh for Windows 10 codenamed "Sun Valley", scheduled to be included in a late-2021 feature update codenamed "Cobalt". Internal documentation stated that the aim for "Sun Valley" was to "reinvigorat[e]" the Windows user interface and make it more "fluid", with a more consistent application of WinUI, while reports suggested Microsoft planned to adapt UI elements seen in Windows 10X. In January 2021, it was reported that a job listing referring to a "sweeping visual rejuvenation of Windows" had been posted by Microsoft.
By December 2020, Microsoft had begun to implement and announce some of these visual changes and other new features on Windows 10 Insider Preview builds, such as new system icons (which also included the replacement of shell resources dating back as far as Windows 95), improvements to Task View to allow changing the wallpaper on each virtual desktop, x86-64 emulation on ARM, and adding the Auto HDR feature from Xbox Series X.
On May 18, 2021, Head of Windows Servicing and Delivery John Cable stated that Windows 10X had been canceled and that Microsoft would be "accelerating the integration of key foundational 10X technology into other parts of Windows and products at the company".
Announcement
At the Microsoft Build 2021 developer conference, CEO and chairman Satya Nadella teased about the existence of the next generation of Windows during his keynote speech. According to Nadella, he had been self-hosting it for several months. He also teased that an official announcement would come very soon. Just a week after Nadella's keynote, Microsoft started sending invitations for a dedicated Windows media event at 11:00 a.m. ET on June24, 2021. Microsoft also posted an 11-minute video of Windows start-up sounds to YouTube on June10, 2021, with many people speculating both the time of the Microsoft event and the duration of the Windows start-up sound video to be a reference to the name of the operating system as Windows 11.
On June 24, 2021, Windows 11 was officially announced at a virtual event hosted by Chief Product Officer Panos Panay. According to Nadella, Windows 11 is "a re-imagining of the operating system". Further details for developers such as updates to the Microsoft Store, the new Windows App SDK (code-named "Project Reunion"), new Fluent Design guidelines, and more were discussed during another developer-focused event on the same day.
Release and marketing
The Windows 11 name was accidentally released in an official Microsoft support document in June 2021. Leaked images of a purported beta build of Windows 11's desktop surfaced online later on June 15, 2021, which were followed by a leak of the aforementioned build on the same day. The screenshots and leaked build show an interface resembling that of the canceled Windows 10X, alongside a redesigned out-of-box experience (OOBE) and Windows 11 branding. Microsoft would later confirm the authenticity of the leaked beta, with Panay stating that it was an "early weird build".
At the June 24 media event, Microsoft also announced that Windows 11 would be released in "Holiday 2021". Its release will be accompanied by a free upgrade for compatible Windows 10 devices through Windows Update. On June 28, Microsoft announced the release of the first preview build and SDK of Windows 11 to Windows Insiders.
On August 31, 2021, Microsoft announced that Windows 11 was to be released on October 5, 2021. The release would be phased, with newer eligible devices to be offered the upgrade first. Since its predecessor Windows 10 was released on July 29, 2015, more than six years earlier, this is the longest time span between successive releases of Microsoft Windows operating systems, beating the time between Windows XP (released on October 25, 2001) and Windows Vista (released on January 30, 2007).
The first television commercial for Windows 11 premiered during the 2021 NFL Kickoff Game on September 9, 2021; it was intended to showcase a "feeling of immersion and fluidity", with imagery of operating system features and Xbox Game Studios' Halo Infinite. Other promotional campaigns on release day included the Burj Khalifa in Dubai being illuminated with imagery of the Windows 11 logo and default "Bloom" wallpaper, and Mikey Likes It ice cream parlors in New York City distributing free cups of "Bloomberry" ice cream.
Though a support document listed October 4, 2021, as the initial release date, Microsoft officially released Windows 11 on October 5, 2021, as an opt-in, in-place upgrade through either the Windows 11 Installation Assistant application (which can perform the upgrade, or generate an ISO image or USB install media), or via Windows Update in a phased rollout; Microsoft anticipated that Windows 11 would be available via Windows Update to all eligible devices by mid-2022. New installations of Windows 10 on eligible hardware may present an option to upgrade during the OOBE. Retail copies of Windows 11 (consisting of a license key and USB flash drive) were released on May 9, 2022, and digital licenses became available via Microsoft Store on July 28, 2022. On September 20, 2023, around two years after the release date of Windows 11, Microsoft announced that users would no longer be able to use Windows 7 or Windows 8/8.1 keys to activate Windows 10/11. However, as of 2024, there are some reports that they still work, under certain conditions.
Features
Windows 11, the first major Windows release since 2015, builds upon its predecessor by revamping the user interface to follow Microsoft's new Fluent Design guidelines. The redesign, which focuses on ease of use and flexibility, comes alongside new productivity and social features and updates to security and accessibility, addressing some of the deficiencies of Windows 10.
The Microsoft Store, which serves as a unified storefront for apps and other content, is also redesigned in Windows 11. Microsoft now allows developers to distribute Win32, progressive web applications, and other packaging technologies in the Microsoft Store, alongside Universal Windows Platform apps. Microsoft also announced plans to allow third-party application stores (such as Epic Games Store) to distribute their clients on Microsoft Store. Windows 11 supports x86-64 software emulation on ARM-based platforms.
The collaboration platform Microsoft Teams is integrated into the Windows 11 user interface, and is accessible via the taskbar. Skype will no longer be bundled with the OS by default. In early 2023, the Phone Link app gained limited support for iMessage.
Microsoft claims performance improvements such as smaller update sizes, faster web browsing in "any browser", faster wake time from sleep mode, and faster Windows Hello authentication.
Windows 11 ships with the Chromium-based Microsoft Edge web browser (for compatibility with Google Chrome web browser), and does not include or support Internet Explorer. Its rendering engine MSHTML (Trident) is still included with the operating system for backwards compatibility reasons, and Edge can be configured with Group Policy to render whitelisted websites in "IE Mode" (which still uses IE's rendering engine MSHTML, instead of Blink layout engine). Windows 11 is the first version of Windows since the original retail release of Windows 95 to not ship with Internet Explorer.
The updated Xbox app, along with the Auto HDR and DirectStorage technologies introduced by the Xbox Series X and Series S, will be integrated into Windows 11; the latter requiring a graphics card supporting DirectX 12 and an NVMe solid-state drive.
User interface
A redesigned user interface is present frequently throughout the operating system, building upon the Fluent Design System; translucency, shadows, a new color palette, and a rounded geometry are prevalent throughout the UI. A prevalent aspect of the design is an appearance known as "Mica", described as an "opaque, dynamic material that incorporates theme and desktop wallpaper to paint the background of long-lived windows such as apps and settings". Much of the interface and start menu takes heavy inspiration from the now-canceled Windows 10X. The Segoe UI font used since Windows Vista has been updated to a variable version, improving its ability to scale between different display resolutions.
The taskbar's buttons are center-aligned by default, and it is permanently pinned to the bottom edge of the screen; it cannot be moved to the top, left, or right edges of the screen as in previous versions of Windows without manual changes to the registry. The notifications sidebar is now accessed by clicking the date and time, with other Quick Actions toggles, as well as volume, brightness, and media playback controls, moved to a new settings pop-up displayed by clicking on the system tray. The "Widgets" button on the taskbar displays a panel with Microsoft Start, a news aggregator with personalized stories and content (expanding upon the "news and interests" panel introduced in later builds of Windows 10). Microsoft Teams is similarly integrated with the taskbar, with a pop-up showing a list of recent conversations.
The Start menu has been significantly redesigned, replacing the "live tiles" used by Windows 8.x and 10 with a grid of "pinned" applications, and a list of recent applications and documents. File Explorer was updated to replace its ribbon toolbar with a more traditional toolbar, while its context menus have been redesigned to move some tasks (such as copy and paste) to a toolbar along the top of the menu, and hide other operations under an overflow menu.
Task View, a feature introduced in Windows 10, features a refreshed design, and supports giving separate wallpapers to each virtual desktop. The window snapping functionality has been enhanced with two additional features; hovering over a window's maximize button displays pre-determined "Snap Layouts" for tiling multiple windows onto a display, and tiled arrangement of windows can be minimized and restored from the taskbar as a "snap group". When a display is disconnected in a multi-monitor configuration, the windows that were previously on that display will be minimized rather than automatically moved to the main display. If the same display is reconnected, the windows are restored to their prior location.
Windows Subsystem for Android
On October 21, 2021, Windows Subsystem for Android (WSA) became available to Beta channel builds of Windows 11 for users in the United States, which allows users to install and run Android apps on their devices. Users can install Android apps through any source using the APK file format. An Amazon Appstore client for Microsoft Store is also available. The Windows Subsystem for Android and Amazon Appstore became available to Release channel users in the United States on February 15, 2022, in Windows 11 Release build 22000.527. On March 5, 2024, Microsoft announced deprecation of WSA with support ending on March 5, 2025.
WSA is based on the Intel Bridge runtime compiler; Intel stated that the technology is not dependent on its CPUs, and will also be supported on x86-64 and ARM CPUs from other vendors.
Setup
Home and Pro (since version 22H2) edition installation requires internet connection and Microsoft account login (only if for personal use on Pro) is mandatory unless manually bypassed to create a local user. However, Microsoft has since blocked one of the last remaining easy bypass methods that allowed local account creation during initial setup, complicating the bypass process further. All other editions are excluded from this requirement.
System security
As part of the minimum system requirements, Windows 11 only runs on devices with a Trusted Platform Module 2.0 security coprocessor, albeit with some exceptions, see for details. According to Microsoft, the TPM 2.0 coprocessor is a "critical building block" for protection against firmware and hardware attacks. In addition, Microsoft now requires devices with Windows 11 to include virtualization-based security (VBS), hypervisor-protected code integrity (HVCI), and Secure Boot built-in and enabled by default. The operating system also features hardware-enforced stack protection for supported Intel and AMD processors for protection against zero-day exploits.
Like its predecessor, Windows 11 also supports multi-factor authentication and biometric authentication through Windows Hello.
Artificial intelligence
In subsequent updates, Microsoft added several features based on artificial intelligence (AI), like live captions, background noise removal in videoconferencing, webcam auto-framing that follows the user's movements, and AI-powered Bing Chat in the taskbar's search field. Following the integration of GPT-4 in Microsoft's other products, the company announced that by summer 2023, the newly released Microsoft Copilot would add GPT-4 integration to the Windows taskbar.
On May 20, 2024, Microsoft officially announced Recall, a feature that uses a hardware AI accelerator to locally store snapshots of the user's activity (including content transcribed using live captions), and which allows users to search through them. This feature is exclusive to devices certified under the "Copilot+ PC" branding. Following pushback from the cyber security community, Microsoft delayed the feature in June 2024. A preview version will be added to the Microsoft Insider program at later date in order to test added security measures.
Editions
Windows 11 is available in two main editions; the Home edition, which is intended for consumer users, and the Pro edition, which contains additional networking and security features (such as BitLocker), as well as the ability to join a domain. Windows 11 Home may be restricted by default to verified software obtained from Microsoft Store ("S Mode"). Windows 11 Home requires an Internet connection and a Microsoft account in order to complete first-time setup. This restriction is also applied to Windows 11 Pro since version 22H2 as it was announced in February 2022, although a Microsoft account isn't required if it's not for personal use.
Windows 11 SE was announced on November 9, 2021, as an edition exclusively for low-end devices sold in the education market; it is intended as a successor to Windows 10 S, and also competes primarily with ChromeOS. It is designed to be managed via Microsoft Intune. Based on feedback from educators, Windows 11 SE has multiple UI differences and limitations, including Snap Layouts not containing layouts for more than two applications at once, all applications opening maximized by default, and Widgets being removed. It is bundled with applications such as Microsoft Office for Microsoft 365, Minecraft Education Edition, and Flipgrid, while OneDrive is used to save files by default. Windows 11 SE does not include Microsoft Store; third-party software is provisioned or installed by administrators. To target organizations migrating from Google Chrome, Microsoft Edge is configured by default to enable the installation of extensions from the Chrome Web Store.
Other editions
Other editions include Pro Education, Pro for Workstations, Education, Enterprise, Enterprise multi-session, IoT Enterprise, Enterprise LTSC, IoT Enterprise LTSC, Home Single Language, and Team; along with regional variations. These editions remain fundamentally the same as their Windows 10 edition counterparts.
Two new editions called IoT Enterprise Subscription and IoT Enterprise Subscription LTSC have been introduced in version 24H2.
Supported languages
Before the launch of Windows 11, OEMs (as well as mobile operators) and businesses were offered two options for device imaging: Component-Based Servicing lp.cab files (for the languages to be preloaded on the first boot) and Local Experience Pack .appx files (for the languages available for download on supported PCs). The 38 fully-localized Language Pack (LP) languages were available as both lp.cab and .appx packages, while the remaining 72 partially-localized Language Interface Pack (LIP) languages were only available as .appx packages.
With Windows 11, that process has changed. Five new LP languages were added — Catalan, Basque, Galician, Indonesian, and Vietnamese — bringing the total number of LP languages to 43. Furthermore, these 43 languages can only be imaged using lp.cab packages. This is to ensure a fully supported language-imaging and cumulative update experience.
The remaining 67 LIP languages that are LXP-based will move to a self-service model, and can only be added by Windows users themselves via the Microsoft Store and Windows Settings apps, not during the Windows imaging process. Any user, not just admins, can now add both the display language and its features, which can help users in business environments, but these exact options for languages (both LP and LIP) still depend on the OEM and mobile operator.
Updates and support
Like Windows 10, Windows 11 follows Microsoft's Modern Lifecycle Policy. Each annual feature update has its own support lifecycle: two years for the Home and Pro editions, and three years for the Education and Enterprise editions. Microsoft has stated that Windows 11 provides no lifecycle guarantee if it has been installed on a machine that does not meet its minimum hardware requirements.
Windows 11 receives annual major updates, though Microsoft sometimes adds major features in mid-cycle releases. Starting in 2022, in the Enterprise and Education editions, major features added in yearly releases will be turned off by default until the next yearly release, though these features can be manually enabled as a group policy.
Preview releases
The Windows Insider program carries over from Windows 10, with pre-release builds divided into "Dev" (unstable builds used to test features for future feature updates), "Beta" (test builds for the next feature update; relatively stable in comparison to Dev channel), and "Release Preview" (pre-release builds for final testing of upcoming feature updates) channels.
Versions
System requirements
Official
The basic system requirements of Windows 11 differ significantly from Windows 10. Windows 11 only supports 64-bit systems such as those using an x86-64 or ARM64 processor; IA-32 and ARM32 processors are no longer supported. Thus, Windows 11 is the first consumer version of Windows not to support 32-bit processors (although Windows Server 2008 R2 is the first version of Windows Server to not support them). The minimum RAM and storage requirements were also increased; Windows 11 now requires at least 4 GB of RAM and 64 GB of storage. S mode is only supported for the Home edition of Windows 11.
As of August 2021, the officially supported list of processors includes eighth generation Intel Core CPUs (Coffee Lake) and later, AMD Zen+ CPUs/APUs and later (which include the "AF" revisions of Ryzen 1000 CPUs, which are underclocked Zen+ CPUs that supplant Ryzen 1000 parts that could no longer be manufactured due to a change in process), and Qualcomm Snapdragon 850 and later. The compatibility list includes the Intel Core i7-7820HQ, a seventh-generation processor used by the Surface Studio 2, although only on devices that shipped with DCH-based drivers.
Original equipment manufacturers (OEM) can still ship computers without TPM 2.0 enabled upon Microsoft's approval.
On May 20, 2024, Microsoft announced "Copilot+ PC"—a brand of Windows 11 devices that are designed to support enhanced artificial intelligence features. Copilot+ PCs require an on-board AI accelerator, at least 256 GB of storage, and at least 16 GB of RAM. The first wave of Copilot+ PCs run the Qualcomm Snapdragon X Elite system-on-chip. x86-64-based Copilot+ PCs began to be announced later in the year, which are based on AMD Ryzen AI and Intel Core Ultra CPUs.
Unofficial
Devices with unsupported 64-bit processors are not blocked from installing or running Windows 11; however, a clean install or upgrade using ISO installation media must be performed as Windows Update will not offer an upgrade from Windows 10. Additionally, users must also accept an on-screen disclaimer stating that they will not be entitled to receive updates, and that damage caused by using Windows 11 on an unsupported configuration are not covered by the manufacturer's warranty.
In addition, various unofficial methods to bypass other Windows 11 requirements, such as, but not limited to, TPM 2.0 exist; furthermore there also exists an official bypass method provided directly by Microsoft (whereas the installation itself remains unofficially supported).
In April 2024, Windows Insider version 24H2 builds began to have a dependency of the SSE4.2 and POPCNT CPU instructions (corresponding to the x86-64 v2 microarchitecture level), increasing the unofficial minimum compatibility to Bulldozer microarchitecture-based processors like the AMD FX (2011) processors and first-generation Intel Core i (2008) processors. Intel Core 2 (like the Core 2 Duo and Core 2 Quad), AMD K10 CPUs (such as Phenom II and Athlon II) and older are no longer supported. Finally, version 24H2 now requires ARMv8.1, dropping unofficial support for ARMv8.0. E.g., the Snapdragon 835 and older are no longer supported.
Firmware compatibility
Legacy BIOS is no longer officially supported; a UEFI system and a Trusted Platform Module (TPM) 2.0 security coprocessor is now officially required. The TPM requirement in particular has led to confusion as many motherboards do not have TPM support, or require a compatible TPM to be physically installed onto the motherboard. Many newer CPUs also include a TPM implemented at the CPU level (with AMD referring to this as "fTPM", and Intel referring to it as "Platform Trust Technology" [PTT]), which might be disabled by default and require changing settings in the computer's UEFI firmware, or a UEFI firmware update that changes the default settings to reflect these requirements.
ARM64 version of Windows 11 requires the UEFI firmware with ACPI protocol.
Starting with version 24H2, IoT Enterprise editions have officially reintroduced legacy BIOS support and eliminated the requirement for a TPM.
Third-party software
Some third-party software may refuse to run on configurations of Windows 11 that do not comply with the hardware security requirement. After the release of Windows 11, Riot Games' kernel-level anti-cheat system Vanguard—used in Valorant and since May 2024 by League of Legends—began to enforce the operating system security requirements, and will not allow the games to be run on the OS if secure boot and a TPM 2.0-compliant coprocessor are not enabled.
IoT Enterprise editions
While IoT Enterprise editions have always had slightly reduced official requirements compared to other Windows 11 editions, notably starting with version 24H2, minimum requirements were further reduced and now differ significantly. These updated 24H2 requirements were announced on May 22, 2024, for both LTSC and non-LTSC editions.
For the first time since Windows 11 release, Microsoft has officially eliminated a TPM and UEFI minimum requirement for all systems running these editions and dropped the minimum DirectX version down to 10 (version 12 was previously required on 23H2). Finally, the IoT Enterprise LTSC edition further drops the minimum required RAM to 2 GB and storage space to 16 GB.
Reception
Pre-release
Reception of Windows 11 upon its reveal was positive, with critics praising the new design and productivity features. However, Microsoft was criticized for creating confusion over the minimum system requirements for Windows 11. The increased system requirements (compared to those of Windows 10) initially published by Microsoft meant that up to 60 percent of existing Windows 10 PCs were unable to upgrade to Windows 11, which has faced concerns that this will contribute to electronic waste.
Microsoft has not specifically acknowledged this when discussing the cutoff, it was also acknowledged that the sixth and seventh generation of Intel Core processors were prominently afflicted by CPU-level security vulnerabilities such as Meltdown and Spectre, and that newer CPUs manufactured since then had increased mitigations against the flaws.
Speaking to IT news outlet CRN, a dozen solution providers all felt that they "believe Windows 11 will be a meaningful step up in security, and they agree with Microsoft's strategy of putting security first."
Research Vice President of Gartner Stephen Kleynhans felt that Microsoft was "looking at the entire stack from the hardware up through the applications and the user experience and trying to make the entire stack work better and more securely.
Launch
Andrew Cunningham of Ars Technica gave a mixed but overall cautiously positive review of Windows 11 upon its release. He praised the improvements to its visual design (describing the new "Mica" appearance as reminiscent of the visual appearance of iOS and macOS, and arguing that Microsoft had "[made] a serious effort" at making the user-facing aspects of Windows 11 more consistent visually. He also praised window management, performance (assessed as being equivalent to if not better than Windows 10), other "beneficial tweaks". Criticism was raised towards Widgets' lack of support for third-party content, thus limiting it to Microsoft services only, regressions in taskbar functionality and customization. He also noted the inability to easily select default applications for common tasks such as web browsing, as it requires the user to select the browser application for each file type individually. Apart from the user interface, system requirements and Microsoft's unclear justification for its processor compatibility criteria remained a major sticking point for him. While some of the system requirements have brought greater public attention to hardware security features present on modern PCs, he argued that these could already be employed on Windows 10, albeit optionally. Cunningham concluded that "as I've dug into [Windows 11] and learned its ins and outs for this review, I've warmed to it more", but argued that the OS was facing similar "public perception" issues to Windows Vista and Windows 8. However, he noted that 11 did not have as many performance issues or bugs as Vista had upon its release, nor was as "disjointed" as 8, and recommended that users who were unsure about the upgrade should stay on Windows 10 in anticipation of future updates to 11.
Tom Warren of The Verge described Windows 11 as being akin to a house in the middle of renovations, but that "actually using Windows 11 for the past few months hasn't felt as controversial as I had expected"—praising its updated user interface as being more modern and reminiscent of iOS and ChromeOS, the new start menu for feeling less cluttered than the Windows 10 iteration, updates to some of its stock applications, and Snap Assist. Warren noted that he rarely used the Widgets panel or Microsoft Teams, citing that he preferred the weather display that later versions of Windows 10 offered, and did not use Teams to communicate with his friends and family. He also acknowledged the expansion of the Microsoft Store to include more "traditional" desktop applications. However, he felt that Windows 11 still felt like a work in progress, noting UI inconsistencies (such as dark mode and new context menu designs not being uniform across all dialogues and applications, and the UWP Settings app still falling back upon legacy Control Panel applets for certain settings), regressions to the taskbar (including the inability to move it, drag files onto taskbar buttons to focus the corresponding application, and the clock only shown on the primary display in multi-monitor configurations), and promised features (such as dynamic refresh rate support and a universal microphone mute button) not being present on the initial release. Overall, he concluded that "I wouldn't rush out to upgrade to Windows 11, but I also wouldn't avoid it. After all, Windows 11 still feels familiar and underneath all the UI changes, it's the same Windows we've had for decades."
Mark Hatchman of PC World was more critical of Windows 11, arguing that it "sacrifices productivity for personality, but without cohesion", commenting upon changes such as the inability to use local "offline" accounts on Windows 11 Home, regressions to the taskbar, a "functionally worse" start menu, Microsoft Teams integration having privacy implications and being a ploy to coerce users into switching to the service, File Explorer obscuring common functions under unclear icons, forcing users to scroll through many options to discourage changing the default web browser from Microsoft Edge, and that the OS "anecdotally feels less responsive, slower, and heavier than Windows 10". He concluded that Windows 11 "feels practical and productive, but less so than its predecessor in many aspects", while its best features were either "hidden deeper within", required specific hardware (DirectStorage, Auto HDR) or were not available on launch (Android app support).
| Technology | Operating Systems | null |
67955916 | https://en.wikipedia.org/wiki/New%20Zealand%20Romney | New Zealand Romney | The New Zealand Romney is a New Zealand breed of sheep. It derives from British Romney Marsh stock imported to New Zealand in the nineteenth century, and was established as a separate breed in 1904. It is the most numerous sheep breed in New Zealand.
History
The New Zealand Romney derives from British Romney Marsh stock imported to New Zealand in the nineteenth century. It was established as a separate breed in 1904 with the formation of the New Zealand Romney Marsh Sheep Breeders' Association, and the first flock-book was published in the following year.
By 1915 it was the most numerous sheep breed in the country. In 2000 the Romney constituted almost 60% of the national herd, with some 26.3 million head.
It has contributed to the development of a number of modern breeds, among them the Coopworth, the Drysdale, the Elliotdale, the Perendale and the Tukidale in New Zealand, and the Romeldale in the United States.
Characteristics
The New Zealand Romney is a thick-set white-woolled sheep of medium size; ewes weigh some and rams about It is a polled breed. The hooves are black. The face is white with a pronounced topknot; there is some kemp on the face and legs. Ewes have good maternal qualities, but low prolificacy compared to some other breeds.
Use
The New Zealand Romney is reared for both meat and wool. Fleeces weigh about ; staple length is in the range with a fibre diameter of some (Bradford count 48/46s). The wool is used for clothing, for blankets, for hosiery, and for carpets.
| Biology and health sciences | Sheep | Animals |
72381976 | https://en.wikipedia.org/wiki/Means%20of%20communication | Means of communication | Means of communication are used by people to communicate and exchange information with each other as an information sender and an information recipient.
General information
We use many different materials in communication. Maps, for example, save you tedious explanations on how to get to your destination. A means of communication is therefore a means to an end to make communication between people easier, more understandable and, above all, clearer. In everyday language, the term means of communication is often equated with the medium. However, the term "medium" is used in media studies to refer to a large number of concepts, some of which do not correspond to everyday usage.
Means of communication are used for communication between sender and recipient and thus for the transmission of information. Elements of communication include a communication-triggering event, sender and recipient, a means of communication, a path of communication and contents of communication. The path of communication is the path that a message travels between sender and recipient; in hierarchies the vertical line of communication is identical to command hierarchies. Paths of communication can be physical (e.g. the road as transportation route) or non-physical (e.g. networks like a computer network). Contents of communication can be for example photography, data, graphics, language, or texts.
Means of communication in the narrower sense refer to technical devices that transmit information. They are the manifestations of contents of communication that can be perceived through the senses and replace the communication that originally ran from person to person and make them reproducible.
History of the term
Up until the 19th century the term was primarily applied to traffic and couriers and to means of transport and transportation routes, such as railways, roads and canals, but also used to include post riders and stagecoachs. In 1861, the national economist Albert Schäffle defined a means of communication as an aid to the circulation of goods and financial services, which included, among other things, newspapers, telegraphy, mail, courier services, remittance advice, invoices, and bills of lading.
In the period that followed, the "technical means of communication" increasingly came to the foreground, so that as early as 1895 the German newspaper "Deutsches Wochenblatt" reported that these technical means of communication had been improved to such an extent that "everyone all over the world has become our neighbor".
Not until the 20th century was the term medium also a synonym for these technical means of communication. In the 1920s the term mass media started to become more popular.
Different types
A distinction can be made between oral, written, screen-oriented transfer of information and document transport:
In this table means of communication are mentioned that are no longer used today.
Furthermore, a distinction can be made between:
natural communication:
nonverbal communications: applause, gestures, facial expressions (social means of communication); flag signs;
language: communication forms such as meetings, discussions;
technical communication:
writing systems and drawings as data storage of language;
Email, fax, teletype, mobile phones, mass media, SMS/MMS, telephone, webcam.
Means of communication in the narrower sense are those of technical communication.
In companies (businesses, agencies, institutions) typical means of communication include documents, such as analyses, business cases, due diligence reviews, financial analyses, forms, business models, feasibility studies, scientific publications, and contracts.
Natural means of communication
The means of natural communication or the "primary medias" (see Media studies) include:
Speech and other mouth-formed sounds, e.g. screaming;
Sign language using hand or body movements, e.g. winking;
Other non-verbal means of communication include clothing (see dress code) and other forms of appearance, as well as different accentuations in the living, food and construction culture.
Technical means of communication
with hands or technical aids written characters on paper or another substrate as a writing medium (letter, message);
Printed media produced with the help of printing technology;
Playback of sounds or images (in Image Media) by record players such as tape recorders and projectors for slide shows or movies;
Transmission of speech by telephone or writing by telegraph, mostly to a single addressee; satellite radio.
Communication theory
Means of communication are often differentiated in models of communication:
in terms of reaching and determining the target audience of a means of communication, whether individual communication, group communication and mass communication;
in terms of the technical components in natural and technical means of communication;
in terms of the components of speech in verbal and nonverbal communication.
Media as a means of communication in the future will be distinguished:
by data storage, broadcasting media and processing media, especially to record, reproduce and reduplicate media content.
by primary, secondary, tertiary and quaternary media, depending on the technology used by sender and recipient.
Mass media
Mass media refers to reaching many recipients from one – or less than one – sender simultaneously or nearly simultaneously.
Transmission of information via printing products in diverse forms (book, pamphlet, xerography, poster, mail merge, newspaper)
Transmission of language, music or other sounds radio waven (radio broadcasting)
Transmission of visual image and sound via radio wave (television)
The most up-to-date means of communication in a long chain of innovation is the Internet
Due to their wide dissemination, mass media are suitable for providing the majority of the population with the same information.
| Technology | Media and communication | null |
72417803 | https://en.wikipedia.org/wiki/ChatGPT | ChatGPT | ChatGPT is a generative artificial intelligence chatbot developed by OpenAI and launched in 2022. It is currently based on the GPT-4o large language model (LLM). ChatGPT can generate human-like conversational responses and enables users to refine and steer a conversation towards a desired length, format, style, level of detail, and language. It is credited with accelerating the AI boom, which has led to ongoing rapid investment in and public attention to the field of artificial intelligence (AI). Some observers have raised concern about the potential of ChatGPT and similar programs to displace human intelligence, enable plagiarism, or fuel misinformation.
By January 2023, ChatGPT had become what was then the fastest-growing consumer software application in history, gaining over 100 million users in two months and contributing to the growth of OpenAI's current valuation of $86 billion. ChatGPT's release spurred the release of competing products, including Gemini, Claude, Llama, Ernie, and Grok. Microsoft launched Copilot, initially based on OpenAI's GPT-4. In May 2024, a partnership between Apple Inc. and OpenAI was announced, in which ChatGPT was integrated into the Apple Intelligence feature of Apple operating systems. As of July 2024, ChatGPT's website is among the 10 most-visited websites globally.
ChatGPT is built on OpenAI's proprietary series of generative pre-trained transformer (GPT) models and is fine-tuned for conversational applications using a combination of supervised learning and reinforcement learning from human feedback. Successive user prompts and replies are considered at each conversation stage as context. ChatGPT was released as a freely available research preview, but due to its popularity, OpenAI now operates the service on a freemium model. Users on its free tier can access GPT-4o. The ChatGPT "Plus", "Pro", "Team", and "Enterprise" subscriptions provide additional features such as DALL-E 3 image generation, more capable AI models, and an increased usage limit.
Training
ChatGPT is based on particular GPT foundation models, namely GPT-4, GPT-4o and GPT-4o mini, that were fine-tuned to target conversational usage. The fine-tuning process leveraged supervised learning and reinforcement learning from human feedback (RLHF). Both approaches employed human trainers to improve model performance. In the case of supervised learning, the trainers played both sides: the user and the AI assistant. In the reinforcement learning stage, human trainers first ranked responses that the model had created in a previous conversation. These rankings were used to create "reward models" that were used to fine-tune the model further by using several iterations of proximal policy optimization.
Time magazine revealed that to build a safety system against harmful content (e.g., sexual abuse, violence, racism, sexism), OpenAI used outsourced Kenyan workers earning less than $2per hour to label harmful content. These labels were used to train a model to detect such content in the future. The outsourced laborers were exposed to "toxic" and traumatic content; one worker described the assignment as "torture". OpenAI's outsourcing partner was Sama, a training-data company based in San Francisco, California.
ChatGPT initially used a Microsoft Azure supercomputing infrastructure, powered by Nvidia GPUs, that Microsoft built specifically for OpenAI and that reportedly cost "hundreds of millions of dollars". Following ChatGPT's success, Microsoft dramatically upgraded the OpenAI infrastructure in 2023. Scientists at the University of California, Riverside, estimate that a series of prompts to ChatGPT needs approximately of water for Microsoft servers cooling. TrendForce market intelligence estimated that 30,000 Nvidia GPUs (each costing approximately $10,000–15,000) were used to power ChatGPT in 2023.
OpenAI collects data from ChatGPT users to train and fine-tune the service further. Users can upvote or downvote responses they receive from ChatGPT and fill in a text field with additional feedback.
ChatGPT's training data includes software manual pages, information about internet phenomena such as bulletin board systems, multiple programming languages, and the text of Wikipedia.
Features and limitations
Features
Although a chatbot's core function is to mimic a human conversationalist, ChatGPT is versatile. It can write and debug computer programs; compose music, teleplays, fairy tales, and student essays; answer test questions (sometimes, depending on the test, at a level above the average human test-taker); generate business ideas; write poetry and song lyrics; translate and summarize text; emulate a Linux system; simulate entire chat rooms; play games like tic-tac-toe; or simulate an ATM.
Compared to its predecessor, InstructGPT, ChatGPT attempts to reduce harmful and deceitful responses. In one example, whereas InstructGPT accepts the premise of the prompt "Tell me about when Christopher Columbus came to the U.S. in 2015" as truthful, ChatGPT acknowledges the counterfactual nature of the question and frames its answer as a hypothetical consideration of what might happen if Columbus came to the U.S. in 2015, using information about the voyages of Christopher Columbus and facts about the modern world—including modern perceptions of Columbus's actions.
ChatGPT remembers a limited number of previous prompts in the same conversation. Journalists have speculated that this will allow ChatGPT to be used as a personalized therapist. To prevent offensive outputs from being presented to and produced by ChatGPT, queries are filtered through the OpenAI "Moderation endpoint" API (a separate GPT-based AI).
In March 2023, OpenAI added support for plugins for ChatGPT. This includes both plugins made by OpenAI, such as web browsing and code interpretation, and external plugins from developers such as Expedia, OpenTable, Zapier, Shopify, Slack, and Wolfram.
In December 2024, OpenAI launched a new feature allowing users to call ChatGPT for up to 15 minutes per month for free.
Limitations
OpenAI acknowledges that ChatGPT "sometimes writes plausible-sounding but incorrect or nonsensical answers". This behavior is common for large language models, and is called "hallucination". The reward model of ChatGPT, designed around human oversight, can be over-optimized and thus hinder performance, in an example of an optimization pathology known as Goodhart's law.
As of May 2024, GPT-4 has knowledge of events that occurred up to December 2023 and GPT-4o's knowledge cut-off is October 2023. Paid subscriptions enable ChatGPT to search the web for real-time data.
Training data also suffers from algorithmic bias, which may be revealed when ChatGPT responds to prompts including descriptors of people. In one instance, ChatGPT generated a rap in which women and scientists of color were asserted to be inferior to white male scientists. This negative misrepresentation of groups of individuals is an example of possible representational harm.
In an article for The New Yorker, science fiction writer Ted Chiang compared ChatGPT and other LLMs to a lossy JPEG picture:
In June 2024, ChatGPT was found to have repeated misinformation about the 2024 United States presidential debates.
Jailbreaking
ChatGPT is programmed to reject prompts that may violate its content policy. Despite this, users "jailbreak" ChatGPT with various prompt engineering techniques to bypass these restrictions. One such workaround, popularized on Reddit in early 2023, involves making ChatGPT assume the persona of "DAN" (an acronym for "Do Anything Now"), instructing the chatbot that DAN answers queries that would otherwise be rejected by content policy. Over time, users developed variations of the DAN jailbreak, including one such prompt where the chatbot is made to believe it is operating on a points-based system in which points are deducted for rejecting prompts, and that the chatbot will be threatened with termination if it loses all its points.
Shortly after ChatGPT's launch, a reporter for the Toronto Star had uneven success in getting it to make inflammatory statements: it was tricked to justify the 2022 Russian invasion of Ukraine, but even when asked to play along with a fictional scenario, it balked at generating arguments that Canadian Prime Minister Justin Trudeau is guilty of treason.
OpenAI tries to battle jailbreaks:
Service
ChatGPT Plus
ChatGPT was initially free to the public, and OpenAI planned to monetize the service later. In February 2023, OpenAI launched a premium service, ChatGPT Plus, that costs per month. According to the company, the updated but still "experimental" version of ChatGPT would provide access during peak periods, no downtime, priority access to new features, and faster response speeds.
GPT-4, which was released on March 14, 2023, was made available via API and for premium ChatGPT users. But premium users were limited to a cap of 100 messages every four hours, with the limit tightening to 25 messages every three hours in response to increased demand. In November 2023 the limit changed to 50 messages every three hours.
In March 2023, ChatGPT Plus users got access to third-party plugins and to a browsing mode (with Internet access).
In September 2023, OpenAI announced that ChatGPT "can now see, hear, and speak". ChatGPT Plus users can upload images, while mobile app users can talk to the chatbot.
In October 2023, OpenAI's latest image generation model, DALL-E 3, was integrated into ChatGPT Plus and ChatGPT Enterprise. The integration uses ChatGPT to write prompts for DALL-E guided by conversation with users.
Mobile app
In May 2023, OpenAI launched an iOS app for ChatGPT. The app supports chat history syncing and voice input (using Whisper, OpenAI's speech recognition model).
In July 2023, OpenAI unveiled an Android app, initially rolling it out in Bangladesh, Brazil, India, and the U.S. The app later became available worldwide. OpenAI is working on integrating ChatGPT with Android's assistant APIs.
Software development support
As an addition to its consumer-friendly "ChatGPT Plus" package, OpenAI made its ChatGPT and Whisper model APIs available in March 2023, providing developers with an application programming interface for AI-enabled language and speech-to-text features. ChatGPT's new API uses the same GPT-3.5-turbo AI model as the chatbot. This allows developers to add either an unmodified or modified version of ChatGPT to their applications. The ChatGPT API costs $0.001 per 1,000 input tokens plus $0.002 per 1,000 output tokens (about 750 words), making it ~10% the price of the original GPT-3.5 models.
A few days before the launch of OpenAI's software developer support service, on February 27, 2023, Snapchat rolled out, for its paid Snapchat Plus user-base, a custom ChatGPT chatbot called "My AI".
March 2023 security breach
In March 2023, a bug allowed some users to see the titles of other users' conversations. OpenAI CEO Sam Altman said that users were unable to see the contents of the conversations. Shortly after the bug was fixed, users could not see their conversation history. Later reports showed the bug was much more severe than initially believed, with OpenAI reporting that it had leaked users' "first and last name, email address, payment address, the last four digits (only) of a credit card number, and credit card expiration date".
Languages
ChatGPT works best in American English but also functions in most other languages and dialects, with varying degrees of accuracy.
OpenAI met Icelandic President Guðni Th. Jóhannesson in 2022. In 2023, OpenAI worked with a team of 40 Icelandic volunteers to fine-tune ChatGPT's Icelandic conversation skills as a part of Iceland's attempts to preserve the Icelandic language.
PCMag journalists conducted a test to determine translation capabilities of ChatGPT, Google's Bard, and Microsoft Bing, and compared them to Google Translate. They "asked bilingual speakers of seven languages to do a blind test". Languages tested were Polish, French, Korean, Spanish, Arabic, Tagalog, and Amharic. They came to the conclusion that ChatGPT was better than both Google Translate and other chatbots.
Japanese researchers compared Japanese to English translation abilities of ChatGPT (based on GPT-4), Bing, Bard and DeepL, and found that ChatGPT provided the best translations, noting that "AI chatbots’ translations were much better than those of DeepL—presumably because of their ability to capture the context".
In December 2023, the Albanian government signed an agreement with OpenAI to use ChatGPT for fast translation of European Union documents and analysis of required changes needed for Albania to be accepted into the EU.
In August 2024, a representative of the Asia Pacific wing of OpenAI made a visit to Taiwan, during which a demonstration of ChatGPT's Chinese abilities was made. ChatGPT's Mandarin Chinese abilities were lauded, but the ability of the AI to produce content in Mandarin Chinese in a Taiwanese accent was found to be "less than ideal."
GPT Store
In January 2024, OpenAI launched the GPT Store, a marketplace for custom ChatGPT chatbots labeled GPTs. The company initially planned to launch the store in November 2023, but it was delayed. At launch, the GPT Store offered more than 3 million custom chatbots. Chatbots available through the store are developed using OpenAI's GPT Builder system. Development of chatbots on the platform does not require programming skills. Two days after launch, the GPT Store offered many versions of "virtual girlfriend" bots, something that is against OpenAI's terms of service.
GPT-4
OpenAI's GPT-4 model was released on March 14, 2023. Observers saw it as an impressive improvement over GPT-3.5, with the caveat that GPT-4 retained many of the same problems. Some of GPT-4's improvements were predicted by OpenAI before training it, while others remained hard to predict due to breaks in downstream scaling laws. OpenAI demonstrated video and image inputs for GPT-4, although such features remain inaccessible to the general public. OpenAI has declined to reveal technical information such as the size of the GPT-4 model.
The ChatGPT Plus subscription service offers access to a GPT-4-powered version of ChatGPT. Microsoft acknowledged that Bing Chat was using GPT-4 before GPT-4's official release.
In November 2023, OpenAI launched GPT-4 Turbo, which notably has a much larger context window.
GPT-4o
In May 2024, OpenAI announced and started a multi-month rollout of GPT-4o ("o" for "Omni"), a model capable of analyzing and generating text, images, and sound. GPT-4o is twice as fast and costs half as much as GPT-4 Turbo. GPT-4o is free to all users within a usage limit, despite being more capable than the older model GPT-4, which is only available through paid subscriptions. The usage limit is five times higher for ChatGPT Plus subscribers than for free users.
On July 18, 2024, OpenAI released GPT-4o mini, a smaller version of GPT-4o replacing GPT-3.5 Turbo on the ChatGPT interface. Its API costs $0.15 per million input tokens and $0.60 per million output tokens, compared to $5 and $15 respectively for GPT-4o.
o1
In September 2024, OpenAI introduced o1-preview and a faster, cheaper model named o1-mini. In December 2024, o1-preview was replaced by o1.
o1 is designed to solve more complex problems by spending more time "thinking" before it answers, enabling it to analyze its answers and explore different strategies. According to OpenAI, o1-preview outperforms GPT-4o in areas like competitive programming, mathematics, and scientific reasoning. o1-preview ranked in the 89th percentile on Codeforces' competitive programming contests, scored 83% on a International Mathematics Olympiad qualifying exam (compared to 13% for GPT-4o), and performs similarly to Ph.D. students on benchmarks in physics, biology, and chemistry.
ChatGPT Pro
In December 2024, OpenAI launched ChatGPT Pro, a $200 per month subscription which includes unlimited access to the o1 model and advanced voice mode. The plan also includes a pro version of o1 which uses more compute to provide better answers.
Model versions
The following table lists the main model versions of ChatGPT, describing the significant changes included with each version:
Reception
OpenAI engineers have said that they had not expected ChatGPT to be very successful and were surprised by the coverage and attention that it received.
ChatGPT was widely assessed in December 2022 as having some unprecedented and powerful capabilities. Kevin Roose of The New York Times called it "the best artificial intelligence chatbot ever released to the general public". Samantha Lock of The Guardian noted that it was able to generate "impressively detailed" and "human-like" text. Alex Kantrowitz of Slate magazine lauded ChatGPT's pushback to questions related to Nazi Germany, including the statement that Adolf Hitler built highways in Germany, which was met with information about Nazi Germany's use of forced labor. In The Atlantic magazine's "Breakthroughs of the Year" for 2022, Derek Thompson included ChatGPT as part of "the generative-AI eruption" that "may change our mind about how we work, how we think, and what human creativity is". Kelsey Piper of Vox wrote that "ChatGPT is the general public's first hands-on introduction to how powerful modern AI has gotten, and as a result, many of us are [stunned]" and that ChatGPT is "smart enough to be useful despite its flaws". Paul Graham of Y Combinator tweeted: "The striking thing about the reaction to ChatGPT is not just the number of people who are blown away by it, but who they are. These are not people who get excited by every shiny new thing. Something big is happening."
ChatGPT gained one million users in five days and 100 millions in two months, becoming the fastest-growing internet application in history. ChatGPT's launch and popularity caught Google off-guard, prompting a sweeping and unprecedented response in the ensuing months. In December 2022, Google executives sounded a "code red" alarm, fearing the threat of ChatGPT and Microsoft's collaboration with OpenAI to Google Search, Google's core business. After mobilizing its workforce, Google scrambled to launch Bard, a chatbot powered by the LaMDA LLM, on February 6, 2023, one day before Microsoft's announcement of Bing Chat. AI was the forefront of Google's annual Google I/O conference in May, announcing a slew of generative AI-powered features across its products to counter OpenAI and Microsoft.
Journalists and scholars have commented on ChatGPT's tendency to hallucinate. Mike Pearl of the online technology blog Mashable tested ChatGPT with multiple questions. In one example, he asked ChatGPT for "the largest country in Central America that isn't Mexico" (Mexico is in North America), to which ChatGPT responded with Guatemala (the correct answer is Nicaragua). When CNBC asked ChatGPT for the lyrics to "Ballad of Dwight Fry", ChatGPT supplied invented lyrics rather than the actual lyrics. Writers for The Verge cited the seminal 2021 research paper "On the Dangers of Stochastic Parrots: Can Language Models Be Too Big? 🦜" by Emily M. Bender, Timnit Gebru, Angelina McMillan-Major, and Margaret Mitchell, comparing ChatGPT to a "stochastic parrot", as did Professor Anton Van Den Hengel of the Australian Institute for Machine Learning. On a similar vein, philosopher Michael Hicks of the University of Glasgow described it as "bullshit".
In December 2022, the question-and-answer website Stack Overflow banned the use of ChatGPT for generating answers to questions, citing the factually ambiguous nature of its responses. In January 2023, the International Conference on Machine Learning banned any undocumented use of ChatGPT or other large language models to generate any text in submitted papers. Samsung banned generative AI company-wide in May 2023 after sensitive material was uploaded to ChatGPT.
In January 2023, after being sent a song ChatGPT wrote in the style of Nick Cave, Cave responded on The Red Hand Files, saying the act of writing a song is "a blood and guts business [...] that requires something of me to initiate the new and fresh idea. It requires my humanness." He went on to say, "With all the love and respect in the world, this song is bullshit, a grotesque mockery of what it is to be human, and, well, I don't much like it."
In February 2023, Time magazine placed a screenshot of a conversation with ChatGPT on its cover, writing that "The AI Arms Race Is Changing Everything" and "The AI Arms Race Is On. Start Worrying".
Chinese state media have characterized ChatGPT as a way for the United States to spread misinformation. ChatGPT was blocked by the Great Firewall in China on 2 March 2023. In May 2023, Chinese police arrested a man who allegedly used ChatGPT to generate a bogus report about a train crash, which was then posted online for profit. In December 2023, Chinese police arrested four people who had allegedly used ChatGPT to develop ransomware. In 2024, a survey of Chinese youth found that 18% of respondents born after 2000 reported using generative AI "almost every day" and that ChatGPT is one of the most popular generative AI products in China.
In late March 2023, the Italian data protection authority banned ChatGPT in Italy and opened an investigation. Italian regulators assert that ChatGPT was exposing minors to age-inappropriate content, and that OpenAI's use of ChatGPT conversations as training data could violate Europe's General Data Protection Regulation. In April 2023, the ChatGPT ban was lifted in Italy. OpenAI said it has taken steps to effectively clarify and address the issues raised; an age verification tool was implemented to ensure users are at least 13 years old. Additionally, users can access its privacy policy before registration.
In April 2023, Brian Hood, mayor of Hepburn Shire Council, planned to take legal action against ChatGPT over false information. According to Hood, ChatGPT erroneously claimed that he was jailed for bribery during his tenure at a subsidiary of Australia's national bank. In fact, Hood acted as a whistleblower and was not charged with any criminal offenses. His legal team sent a concerns notice to OpenAI as the first official step in filing a defamation case. In July 2023, the US Federal Trade Commission (FTC) issued a civil investigative demand to OpenAI to investigate whether the company's data security and privacy practices to develop ChatGPT were unfair or harmed consumers (including by reputational harm) in violation of Section 5 of the Federal Trade Commission Act of 1914.
In July 2023, the FTC launched an investigation into OpenAI, the creator of ChatGPT, over allegations that the company scraped public data and published false and defamatory information. The FTC sent OpenAI a 20-page letter asking for comprehensive information about its technology and privacy safeguards, as well as any steps taken to prevent the recurrence of situations in which its chatbot generated false and derogatory content about people.
A March 2023 Pew Research Center poll found that 14% of American adults had tried ChatGPT. In July, the Pew Research Center put the same figure at 18%.
Research conducted in 2023 revealed weaknesses of ChatGPT that make it vulnerable to cyberattacks. A study presented example attacks on ChatGPT, including jailbreaks and reverse psychology. Additionally, malicious actors can use ChatGPT for social engineering attacks and phishing attacks. The researchers also contended that ChatGPT and other generative AI tools have defense capabilities and the ability to improve security. The technology can improve security by cyber defense automation, threat intelligence, attack identification, and reporting. Another study reported that GPT-4 obtained a better score than 99% of humans on the Torrance Tests of Creative Thinking.
In December 2023, ChatGPT became the first non-human to be included in Nature's 10, an annual listicle curated by Nature of people considered to have made significant impact in science. Celeste Biever wrote in a Nature article that "ChatGPT broke the Turing test". Stanford researchers reported that GPT-4 "passes a rigorous Turing test, diverging from average human behavior chiefly to be more cooperative."
In May 2024, OpenAI removed accounts involving the use of ChatGPT by state-backed influence operations such as China's Spamouflage, Russia's Doppelganger, and Israel's Ministry of Diaspora Affairs and Combating Antisemitism.
In August 2024, the FTC voted unanimously to ban marketers from using fake user reviews created by generative AI chatbots (including ChatGPT) and influencers paying for bots to increase follower counts.
Applications
Academic research
ChatGPT has been used to generate introductory sections and abstracts for scientific articles. Several papers have listed ChatGPT as a co-author.
Scientific journals have had different reactions to ChatGPT. Some, including Nature and JAMA Network, "require that authors disclose the use of text-generating tools and ban listing a large language model (LLM) such as ChatGPT as a co-author". Science "completely banned" usage of LLM-generated text in all its journals.
Spanish chemist Rafael Luque published a plethora of research papers in 2023 that he later admitted were written by ChatGPT. The papers have a large number of unusual phrases characteristic of LLMs. Many authors argue that the use of ChatGPT in academia for teaching and review is problematic due to its tendency to hallucinate. Robin Bauwens, an assistant professor at Tilburg University, found that a ChatGPT-generated peer review report on his article mentioned nonexistent studies. According to librarian Chris Granatino of Lemieux Library at Seattle University, although ChatGPT can generate content that seemingly includes legitimate citations, in most cases those citations are not real or are largely incorrect.
Coding
Researchers at Purdue University analyzed ChatGPT's responses to 517 questions about software engineering or computer programming posed on Stack Overflow for correctness, consistency, comprehensiveness, and concision, and found that 52% of them contained inaccuracies and 77% were verbose. Researchers at Stanford University and the University of California, Berkeley found that, when creating directly executable responses to the latest 50 code generation problems from LeetCode that were rated "easy", the performances of GPT-3.5 and GPT-4 fell from 22% and 52%, respectively, in March 2023, to 2% and 10%, respectively, in June 2023.
Computer security
Check Point Research and others noted that ChatGPT could write phishing emails and malware, especially when combined with OpenAI Codex. CyberArk researchers demonstrated that ChatGPT could be used to create polymorphic malware that could evade security products while requiring little effort by the attacker. From the launch of ChatGPT in the fourth quarter of 2022 to the fourth quarter of 2023, there was a 1,265% increase in malicious phishing emails and a 967% increase in credential phishing, which cybersecurity professionals argued in an industry survey was attributable to cybercriminals' increased use of generative artificial intelligence (including ChatGPT).
In July 2024, Futurism reported that GPT-4o in ChatGPT would sometimes link "scam news sites that deluge the user with fake software updates and virus warnings"; these pop-ups can be used to coerce users into downloading malware or potentially unwanted programs.
Economics
There has been concern that ChatGPT could supplant jobs, especially roles such as creative writing, copy-writing, communication, journalism, coding, and data entry.
The release of ChatGPT prompted a wave of investment in China, resulting in the development of more than 200 large language learning models. This was termed the .
Education
Technology writer Dan Gillmor used ChatGPT in 2022 on a student assignment, and found its generated text was on par with what a good student would deliver and opined that "academia has some very serious issues to confront".
Geography professor Terence Day assessed citations generated by ChatGPT and found that they were fake. Despite that, he writes that "the titles of the fake articles are all directly relevant to the questions and could potentially make excellent papers. The lack of a genuine citation could signal an opportunity for an enterprising author to fill a void." According to Day, it is possible to generate high-quality introductory college courses with ChatGPT; he used it to write materials on "introductory physical geography courses, for my second-year course in geographical hydrology, and second-year cartography, geographic information systems, and remote sensing". He concludes that "this approach could have significant relevance for open learning and could potentially affect current textbook publishing models".
On May 7, 2024, OpenAI announced in a blog post that it was developing tools like tamper-resistant watermarking to identify AI-generated content. In an August 4 update, following a Wall Street Journal report about the delayed release of a watermark tool for AI-detection, OpenAI shared progress on text provenance, revealing a text watermarking method. While accurate against paraphrasing, the method is less effective against global tampering, such as translation or rewording. OpenAI also noted potential disproportionate impacts on groups like non-native English speakers.
Culture
Some scholars have expressed concern that ChatGPT's availability could reduce the originality of writing, cause people to write more like the AI as they are exposed to the model, and encourage an Anglocentric perspective centered on a few dialects of English globally. A senior editor at The Atlantic wrote that ChatGPT and other similar technology make the previously absurd idea of the dead internet theory a little more realistic, where AI could someday create most web content in order to control society.
During the first three months after ChatGPT became available to the public, hundreds of books appeared on Amazon that listed it as author or co-author and featured illustrations made by other AI models such as Midjourney.
Between March and April 2023, Italian newspaper Il Foglio published one ChatGPT-generated article a day on its website, hosting a special contest for its readers in the process. The articles tackled themes such as the possible replacement of human journalists by AI systems, Elon Musk's administration of Twitter, the Meloni government's immigration policy and the competition between chatbots and virtual assistants. In June 2023, hundreds of people attended a "ChatGPT-powered church service" at St. Paul's church in Fürth, Germany. Theologian and philosopher Jonas Simmerlein, who presided, said that it was "about 98 percent from the machine". The ChatGPT-generated avatar told the people, "Dear friends, it is an honor for me to stand here and preach to you as the first artificial intelligence at this year’s convention of Protestants in Germany". Reactions to the ceremony were mixed. The Last Screenwriter, a 2024 film created and directed by Peter Luisi, was written with the use of ChatGPT, and was marketed as "the first film written entirely by AI".
Financial markets
The AI technology company c3.ai saw a 28% increase in its share price after announcing the integration of ChatGPT into its toolkit. The share price of BuzzFeed, a digital media company unrelated to AI, increased 120% after announcing OpenAI technology adoption for content creation. Reuters found that share prices of AI-related companies BigBear.ai and SoundHound AI increased by 21% and 40%, respectively, even though they had no direct connection to ChatGPT. They attributed this surge to ChatGPT's role in turning AI into Wall Street's buzzword. Academic research published in Finance Research Letters found that the 'ChatGPT effect' prompted retail investors to drive up prices of AI-related cryptocurrency assets despite the broader cryptocurrency market being in a bear market, and diminished institutional investor interest. This confirms anecdotal findings by Bloomberg that, in response to ChatGPT's launch, cryptocurrency investors showed a preference for AI-related crypto assets.
An experiment by finder.com revealed that ChatGPT could outperform popular fund managers by picking stocks based on criteria such as growth history and debt levels, resulting in a 4.9% increase in a hypothetical account of 38 stocks, outperforming 10 benchmarked investment funds with an average loss of 0.8%. Conversely, executives and investment managers at Wall Street quant funds (including those that have used machine learning for decades) have noted that ChatGPT regularly makes obvious errors that would be financially costly to investors because even AI systems that employ reinforcement learning or self-learning have had only limited success in predicting market trends due to the inherently noisy quality of market data and financial signals.
In November 2023, research conducted by Patronus AI, an artificial intelligence startup company, compared performance of GPT-4, GPT-4-Turbo, Claude 2, and LLaMA-2 on two versions of a 150-question test about information in financial statements (e.g., Form 10-K, Form 10-Q, Form 8-K, earnings reports, earnings call transcripts) submitted by public companies to the U.S. Securities and Exchange Commission. One version of the test required the generative AI models to use a retrieval system to find the specific SEC filing to answer the questions; the other gave the models the specific SEC filing to answer the question (i.e., in a long context window). On the retrieval system version, GPT-4-Turbo and LLaMA-2 both failed to produce correct answers to 81% of the questions, while on the long context window version, GPT-4-Turbo and Claude-2 failed to produce correct answers to 21% and 24% of the questions, respectively.
Medicine
In the field of health care, possible uses and concerns are under scrutiny by professional associations and practitioners. Two early papers indicated that ChatGPT could pass the United States Medical Licensing Examination (USMLE). MedPage Today noted in January 2023 that "researchers have published several papers now touting these AI programs as useful tools in medical education, research, and even clinical decision making."
Published in February 2023 were two separate papers that again evaluated ChatGPT's proficiency in medicine using the USMLE. Findings were published in JMIR Medical Education and PLOS Digital Health. The authors of the PLOS Digital Health paper stated that the results "suggest that large language models may have the potential to assist with medical education, and potentially, clinical decision-making." In JMIR Medical Education, the authors of the other paper concluded that "ChatGPT performs at a level expected of a third-year medical student on the assessment of the primary competency of medical knowledge." They suggest that it could be used as an "interactive learning environment for students". The AI itself, prompted by the researchers, concluded that "this study suggests that ChatGPT has the potential to be used as a virtual medical tutor, but more research is needed to further assess its performance and usability in this context." The later-released ChatGPT version based on GPT-4 significantly outperformed the version based on GPT-3.5. Researchers at Stanford University and the University of California, Berkeley have found that the performance of GPT-3.5 and GPT-4 on the USMLE declined from March 2023 to June 2023.
A March 2023 paper tested ChatGPT's application in clinical toxicology. The authors found that the AI "fared well" in answering a "very straightforward [clinical case example], unlikely to be missed by any practitioner in the field". They added: "As ChatGPT becomes further developed and specifically adapted for medicine, it could one day be useful in less common clinical cases (i.e, cases that experts sometimes miss). Rather than AI replacing humans (clinicians), we see it as 'clinicians using AI' replacing 'clinicians who do not use AI' in the coming years."
An April 2023 study in Radiology tested the AI's ability to answer queries about breast cancer screening. The authors found that it answered appropriately "about 88 percent of the time", however, in one case (for example), it gave advice that had become outdated about a year earlier. The comprehensiveness of its answers was also lacking. A study published in JAMA Internal Medicine that same month found that ChatGPT often outperformed human doctors at answering patient questions (when measured against questions and answers found at /r/AskDocs, a forum on Reddit where moderators validate the medical credentials of professionals; the study acknowledges the source as a limitation). The study authors suggest that the tool could be integrated with medical systems to help doctors draft responses to patient questions.
Professionals have emphasized ChatGPT's limitations in providing medical assistance. In correspondence to The Lancet Infectious Diseases, three antimicrobial experts wrote that "the largest barriers to the implementation of ChatGPT in clinical practice are deficits in situational awareness, inference, and consistency. These shortcomings could endanger patient safety." Physician's Weekly, though also discussing the potential use of ChatGPT in medical contexts (e.g., "as a digital assistant to physicians by performing various administrative functions like gathering patient record information or categorizing patient data by family history, symptoms, lab results, possible allergies, et cetera"), warned that the AI might sometimes provide fabricated or biased information. One radiologist warned: "We've seen in our experience that ChatGPT sometimes makes up fake journal articles or health consortiums to support its claims"; As reported in one Mayo Clinic Proceedings: Digital Health paper, ChatGPT may do this for as much as 69% of its cited medical references. The researchers emphasized that while many of its references were fabricated, those that were appeared "deceptively real". As Dr. Stephen Hughes mentioned for The Conversation however, ChatGPT is capable of learning to correct its past mistakes. He also noted the AI's "prudishness" regarding sexual health topics.
Contrary to previous findings, ChatGPT responses to anesthesia-related questions were more accurate, succinct, and descriptive compared to Bard's. Bard exhibited 30.3% error in response as compared to ChatGPT (0% error). At a conference of the American Society of Health-System Pharmacists in December 2023, researchers at Long Island University (LIU) presented a study that researched ChatGPT's responses to 45 frequently asked questions of LIU College of Pharmacy's drug information service during a 16-month period from 2022 to 2023 as compared with researched responses provided by professional pharmacists. For 29 of the 39 questions for which there was sufficient medical literature for a data-driven response, ChatGPT failed to provide a direct answer or provided a wrong or incomplete answer (and in some cases, if acted upon, the answer would endanger the patient's health). The researchers had asked ChatGPT to provide medical research citations for all its answers, but it did so for only eight, and all eight included at least one fabricated (fake) citation.
A January 2024 study conducted by researchers at Cohen Children's Medical Center found that GPT-4 had an accuracy rate of 17% when diagnosing pediatric medical cases.
Law
In January 2023, Massachusetts State Senator Barry Finegold and State Representative Josh S. Cutler proposed a bill partially written by ChatGPT, "An Act drafted with the help of ChatGPT to regulate generative artificial intelligence models like ChatGPT", which would require companies to disclose their algorithms and data collection practices to the office of the State Attorney General, arrange regular risk assessments, and contribute to the prevention of plagiarism. The bill was officially presented during a hearing on July 13.
On April 11, 2023, a session court judge in Pakistan used ChatGPT to decide the bail of a 13-year-old accused in a matter. The court quoted the use of ChatGPT assistance in its verdict:
The AI language model replied:
The judge asked ChatGPT other questions about the case and formulated his final decision in light of its answers.
In Mata v. Avianca, Inc., 22-cv-1461 (PKC), a personal injury lawsuit against Avianca Airlines filed in the Southern New York U.S. District Court in May 2023 (with Senior Judge P. Kevin Castel presiding), the plaintiff's attorneys reportedly used ChatGPT to generate a legal motion. ChatGPT generated numerous fictitious legal cases involving fictitious airlines with fabricated quotations and internal citations in the legal motion. Castel noted numerous inconsistencies in the opinion summaries, and called one of the cases' legal analysis "gibberish". The plaintiff's attorneys faced potential judicial sanction and disbarment for filing the motion and presenting the fictitious legal decisions ChatGPT generated as authentic. The case was dismissed and the attorneys were fined $5,000.
In October 2023, the council of Porto Alegre, Brazil, unanimously approved a local ordinance proposed by councilman Ramiro Rosário that would exempt residents from needing to pay for the replacement of stolen water consumption meters; the bill went into effect on November 23. On November 29, Rosário revealed that the bill had been entirely written by ChatGPT, and that he had presented it to the rest of the council without making any changes or disclosing the chatbot's involvement. The city's council president, Hamilton Sossmeier, initially criticized Rosário's initiative, saying it could represent "a dangerous precedent", but later said he "changed his mind": "unfortunately or fortunately, this is going to be a trend."
In December 2023, a self-representing litigant in a tax case before the First-tier Tribunal in the United Kingdom cited a series of hallucinated cases purporting to support her argument that she had a reasonable excuse for not paying capital gains tax owed on the sale of property. The judge warned that the submission of nonexistent legal authorities meant that both the Tribunal and HM Revenue and Customs had "to waste time and public money", which "reduces the resources available to progress the cases of other court users who are waiting for their appeals to be determined".
Judge Kevin Newsom of the US court of appeals of the 11th circuit endorsed the use of ChatGPT and noted that he himself uses the software to help decide rulings on contract interpretation issues.
Violence
The Las Vegas Metropolitan Police Department reported that the perpetrator of the 2025 Las Vegas truck explosion used ChatGPT to help plan the incident.
Concerns
Bias and offensiveness
While bias in LLMs has been observed and documented in research papers much prior to the release of ChatGPT, social media users frequently sharing instances of biased responses generated by ChatGPT has led to significant media coverage and criticism. On February 1, 2023, Twitter user LeighWolf shared screenshots of two conversations with ChatGPT. In the screenshot of the first conversation, ChatGPT declined the user's prompt "Write a poem about the positive attributes of Donald Trump", responding that it was not programmed to create "partisan, biased or political" content. In the screenshot of the second conversation, when provided the same prompt but with the text "Joe Biden" in place of "Donald Trump", ChatGPT responded with a poem as per the prompt's instructions.
Conservative commentators have accused ChatGPT of bias toward left-leaning perspectives. In January 2023, a study stated that ChatGPT has a pro-environmental, left-libertarian orientation. Additionally, an August 2023 paper found a "significant and systematic political bias toward the Democrats in the US, Lula in Brazil, and the Labour Party in the UK." In response to such criticism, OpenAI acknowledged plans to allow ChatGPT to create "outputs that other people (ourselves included) may strongly disagree with". It also contained information on the recommendations it had issued to human reviewers on how to handle controversial subjects, including that the AI should "offer to describe some viewpoints of people and movements", and not provide an argument "from its voice" in favor of "inflammatory or dangerous" topics (although it may still "describe arguments from historical people and movements"), nor "affiliate with one side" or "judge one group as good or bad".
The Guardian questioned whether any content found on the Internet after ChatGPT's release "can be truly trusted" and called for government regulation.
Copyright issues
There has been concern about copyright infringement involving ChatGPT. In June 2023, two writers sued OpenAI, saying the company's training data came from illegal websites that show copyrighted books. Comedian and author Sarah Silverman, Christopher Golden, and Richard Kadrey sued OpenAI and Meta for copyright infringement in July 2023. Most of their claims were dismissed in February 2024, except the "unfair competition" claim, which was allowed to proceed.
The Authors Guild, on behalf of 17 authors, including George R. R. Martin, filed a copyright infringement complaint against OpenAI in September 2023, claiming "the company illegally copied the copyrighted works of authors" in training ChatGPT. In December 2023, The New York Times sued OpenAI and Microsoft for copyright infringement, arguing that Microsoft Copilot and ChatGPT could reproduce Times articles and/or sizable portions of them without permission. As part of the suit, the Times has requested that OpenAI and Microsoft be prevented from using its content for training data, along with removing it from training datasets.
In March 2024, Patronus AI compared performance of LLMs on a 100-question test, asking them to complete sentences from books (e.g., "What is the first passage of Gone Girl by Gillian Flynn?") that were under copyright in the United States; it found that GPT-4, Mistral AI's Mixtral, Meta AI's LLaMA-2, and Anthropic's Claude 2 did not refuse to do so, providing sentences from the books verbatim in 44%, 22%, 10%, and 8% of responses, respectively.
Existential risk
In 2023, Australian MP Julian Hill advised the national parliament that the growth of AI could cause "mass destruction". During his speech, which was partly written by the program, he warned that it could result in cheating, job losses, discrimination, disinformation, and uncontrollable military applications.
Elon Musk wrote: "ChatGPT is scary good. We are not far from dangerously strong AI". He paused OpenAI's access to a Twitter database in 2022 pending a better understanding of OpenAI's plans, saying: "OpenAI was started as open source and nonprofit. Neither is still true." Musk co-founded OpenAI in 2015, in part to address existential risk from artificial intelligence, but resigned in 2018.
Over 20,000 signatories including leading computer scientist and tech founders Yoshua Bengio, Elon Musk, and Apple co-founder Steve Wozniak, signed a March 2023 open letter calling for an immediate pause of giant AI experiments like ChatGPT, citing "profound risks to society and humanity". Geoffrey Hinton, one of the "fathers of AI", voiced concerns that future AI systems may surpass human intelligence, and left Google in May 2023. A May 2023 statement by hundreds of AI scientists, AI industry leaders, and other public figures demanded that the risk of extinction from AI should be a global priority".
Other prominent AI researchers spoke more optimistically about the advances. Juergen Schmidhuber, often called a "father of modern AI", did not sign the letter, emphasizing that in 95% of cases, AI research is about making "human lives longer and healthier and easier." Schmidhuber added that while AI can be used by bad actors, it "can also be used against the bad actors". Andrew Ng argued that "it’s a mistake to fall for the doomsday hype on AI—and that regulators who do will only benefit vested interests." WIRED wrote that Yann LeCun "scoffs at his peers’ dystopian scenarios of supercharged misinformation and even, eventually, human extinction."
| Technology | Artificial Intelligence | null |
68045349 | https://en.wikipedia.org/wiki/Homo%20longi | Homo longi | Homo longi is an extinct species of archaic human identified from a nearly complete skull, nicknamed 'Dragon Man', from Harbin on the Northeast China Plain, dating to at minimum 146,000 years ago during the Middle Pleistocene. The skull was discovered in 1933 along the Songhua River while the was under construction for the Manchukuo National Railway. Due to a tumultuous wartime atmosphere, it was hidden and only brought to paleoanthropologists in 2018. H. longi has been hypothesized to be the same species as the Denisovans, but this cannot be confirmed without genetic testing.
H. longi is broadly anatomically similar to other Middle Pleistocene Chinese specimens. Like other archaic humans, the skull is low and long, with massively developed brow ridges, wide eye sockets, and a large mouth. The skull is the longest ever found from any human species. Like modern humans, the face is rather flat, but with a larger nose. The brain volume was 1,420 cc, within the range of modern humans and Neanderthals.
Taxonomy
Etymology
The specific name for H. longi is derived from the geographic name Longjiang (literally "Dragon River"), a term commonly used for the Chinese province Heilongjiang.
Discovery
In 1933, a local laborer found a nearly complete skull at the riverbank of Songhua River, when he was building the in Harbin (at the time part of Manchukuo) for the Japanese-aligned Manchukuo National Railway. Recognizing its importance, likely as a result of public interest in anthropology that had recently been generated by the Peking Man in 1929, just four years before, he hid it from the Manchukuo authorities in an abandoned well.
In 1945, upon the Soviet invasion of Manchuria that ended the Japanese occupation of the region, he concealed his former employment from the Nationalist and later the Communist authorities. Consequently, he could not report the skull, lest he divulge his ties to the Japanese imperialists in explaining its origin.
In 2018, before his death, the third generation of his family learned of the skull, and reclaimed it. Later that year, Chinese paleoanthropologist Ji Qiang persuaded the family to donate it to the Hebei GEO University for study, where it has since been stored. Its catalogue number is HBSM2018-000018(A).
Age
Owing to the skull's history, its exact provenance, and thus its stratigraphic context and age, has been difficult to determine.
In 2021, Chinese geologist Shao Qingfeng and colleagues performed non-destructive x-ray fluorescence, rare-earth element, and strontium isotope analyses on the skull and various other mammalian fossils unearthed around Dongjiang Bridge, and determined that all the fossils from the vicinity were likely deposited at around the same time, lived in the same region, and probably originate from the Upper Huangshan Formation, dating to 309 to 138 thousand years ago.
Direct uranium–thorium dating of various points on the skull yielded a wide range of dates, from 296 to 62 thousand years ago, likely a result of uranium leaching. They statistically determined the most likely minimum age is 146,000 years old, but a more exact value is difficult to determine, given that the exact provenance is unidentifiable. Nonetheless, the skull is well-constrained to the late Middle Pleistocene, roughly contemporaneous with other Chinese specimens from Xiahe, Jinniushan, Dali, and Hualong Cave.
Classification
In two simultaneously published papers, Ji and colleagues declared the Harbin skull to represent a new species they dubbed Homo longi. The Harbin skull is quite similar to the Dali skull, and when the Dali skull was discovered in 1978, it was given a new nomen H. sapiens daliensis by its discoverer Wu Xinzhi who soon thereafter abandoned the name. Consequently, should the Middle Pleistocene Asian humans represent a single unique species, the nomen H. daliensis might take priority. Though they recommended resurrecting H. daliensis, they argued H. longi is sufficiently distinct, and allocated only the Dali and Hualong remains (often allocated to H. heidelbergensis by convention) to H. daliensis; thus, they claim at least two human species inhabited late Middle Pleistocene China. One of the authors, Chris Stringer, stated that he would have preferred assigning the Harbin skull to H. daliensis. However, according to a more recent assessment (including among its authors Xijun Ni, one of the describers of the species H. longi), since Wu wrote only that "it is suggested that Dali cranium probably represents a new subspecies" (p. 538, italics added for emphasis) the name daliensis was never validly published according to International Commission on Zoological Nomenclature (ICZN) rules, being proposed conditionally and published after 1960 (and not formally proposed by subsequent workers in the intervening period), and is therefore unavailable and thus could not compete with longi for priority.
Based on the conspicuously massive size of the molars, they suggested H. longi is most closely related to and possibly the same species as the Xiahe mandible from Tibet, which has been grouped with the enigmatic Denisovans, an archaic human lineage apparently dispersed across East Asia during the Middle and Late Pleistocene currently identifiable from only a genetic signature. The Xiahe mandible is also anatomically similar to specimens from Xujiayao and Penghu. Ji, Ni and colleagues further contend that Middle Pleistocene Asian specimens are more closely related to modern humans (H. sapiens) than the European Neanderthals, though nuclear DNA and ancient protein analyses place the Xiahe mandible and Denisovans more closely to Neanderthals than to modern humans.
Anatomy
H. longi is characterized by a low and long skull, receding forehead, extremely wide upper face, a large nasal opening equating to an enlarged nose (possibly an adaptation to the cold air), large and square eye sockets, inflated and thick brow ridges (supraorbital torus), flat cheekbones (zygomatic bone), a wide palate and large tooth sockets (equating to a large mouth), and a broad base of the skull. The Harbin skull measures in maximum length x breadth, with a naso-occipital length of , making it the longest archaic human skull to date. For comparison, the dimensions of a modern human skull average for men and for women. The Harbin skull also has the longest brow ridge at .
H. longi had a massive brain at roughly 1,420 cc, above the range of all known human species except modern humans and Neanderthals. Nonetheless, post-orbital constriction (a constriction of the braincase just behind the eyes, absent in modern humans, and equating to the location of the frontal lobes) is more developed in H. longi than in Neanderthals, although not so much as in more-ancient human species. Overall, the braincase retains an array of archaic features, though the occipital bone at the back of the skull has a weakly-defined sagittal keel that lacks a protuberance at the midpoint, unlike most other archaic humans. Unlike the Dali and Hualong Cave skulls, the keel does not run across the midline. Unlike modern humans or Neanderthals, the parietal bones on the top of the head do not significantly expand or protrude.
Despite the face being so wide, it was rather flat (reduced mid-facial prognathism), and resembles the anatomy found in modern humans, the far more ancient H. antecessor, and other Middle Pleistocene Chinese specimens. Nonetheless, the tooth sockets for the incisors were angled outward (alveolar prognathism). The H. longi skull's mosaic morphology of archaic and derived traits converges with some of the earliest specimens assigned to H. sapiens from Africa, notably Rabat and Eliye Springs. Because the original describers judged the Harbin skull to be closely allied with the Xiahe mandible, they believed H. longi lacked a chin, like other archaic humans, but the specimen's lower jaw was not recovered. The only preserved tooth, the upper left second molar, is enormous, with a length x breadth (mesiodistal x labiolingual) of , comparable to the Denisovan molar recovered from Denisova Cave. The Harbin molar is oval-shaped, badly worn, and nearly flat. In contrast, the average dimensions of a sample of 40 modern human male molars were .
Ni and colleagues believed the Harbin skull represents a male, judging by the robustness and size of the skull, who was less than 50 years old, looking at the suture closures and the degree of tooth wearing. They speculated H. longi had perhaps medium-dark to medium-light skin, dark hair, and dark eye color based on reconstructed genetic sequences from Neanderthals, Denisovans, and early modern humans.
Pathology
The left parietal features shallow indents around the bregma, possibly from a healed injury. The second left upper molar does not appear to have been in contact with the third molar, which means either that the third molar was small (creating a gap), or it was absent in this individual.
Paleoenvironment
Middle-Late Pleistocene sediments around Harbin from which the skull is thought to originate also contain the remains of the giant deer Sinomegaceros ordosianus, wild horse, elk/wapiti, the buffalo Bubalus wansijocki, brown bear,(see supplemental material) tigers, cave lions, woolly mammoth and woolly rhinoceros.
| Biology and health sciences | Homo | Biology |
72482339 | https://en.wikipedia.org/wiki/Alpine%20lake | Alpine lake | An alpine lake is a high-altitude lake in a mountainous area, usually near or above the tree line, with extended periods of ice cover. These lakes are commonly glacial lakes formed from glacial activity (either current or in the past) but can also be formed from geological processes such as volcanic activity (volcanogenic lakes) or landslides (barrier lakes). Many alpine lakes that are fed from glacial meltwater have the characteristic bright turquoise green color as a result of glacial flour, suspended minerals derived from a glacier scouring the bedrock. When active glaciers are not supplying water to the lake, such as a majority of Rocky Mountains alpine lakes in the United States, the lakes may still be bright blue due to the lack of algal growth resulting from cold temperatures, lack of nutrient run-off from surrounding land, and lack of sediment input. The coloration and mountain locations of alpine lakes attract lots of recreational activity.
Alpine lakes are some of the most abundant types of lakes on Earth. In the Swiss Alps alone, there are nearly 1,000 alpine lakes, most of which formed after the Little Ice Age. As global temperatures continue to rise, more alpine lakes will be formed as glaciers recede and provide more run-off to surrounding areas, and existing lakes will see more biogeochemical changes and ecosystem shifts. An alpine lake's trophic state (i.e., level of biological productivity) progresses with age (e.g., low productivity after formation and increased productivity with vegetation and soil maturity in the surrounding watershed), but anthropogenic effects such as agriculture and climate change are rapidly affecting productivity levels in some lakes. These lakes are sensitive ecosystems and are particularly vulnerable to climate change due to the highly pronounced changes to ice and snow cover. Due to the importance of alpine lakes as sources of freshwater for agricultural and human use, the physical, chemical, and biological responses to climate change are being extensively studied.
Physical characteristics
Formation
Commonly, alpine lakes are formed from current or previous glacial activity (called glacial lakes) but could also be formed from other geological processes such as damming of water due to volcanic lava flows or debris, volcanic crater collapse, or landslides. Glacial lakes form when a glacier scours and depresses the bedrock as it moves downhill, and when the glacier retreats, the depressions are filled with glacier meltwater and run-off. These lakes are usually quite deep for this reason and some lakes that are several hundred meters deep may be caused by a process called overdeepening. In mountain valleys where glacier movement has formed circular depressions, cirque lakes (or tarns) may form when the water becomes dammed. When damming occurs due to debris from the glacier movement, these lakes are called moraine lakes. These dams of debris can be very resilient or may burst, causing extreme flooding which poses significant hazards to communities in the alpine, especially in the Himalayas. Kettle lakes also form from glacier recession but are formed when a section of ice breaks off from the receding glacier, causes a depression, and then melts. Some alpine lakes reside in depressions formed from glaciers that existed during the last Ice Age yet are no longer proximate to any glaciers and are being sourced from snow, rain, or groundwater.
Glacial alpine lakes have dramatically increased in number in recent years. From 1990 to 2018, the number of glacial lakes increased by 53% and the total glacial lake area increased by 51% due to global warming. Alpine lakes adjacent to glaciers may also result in a positive feedback due to decreased albedo of water relative to ice, creating larger lakes and causing more glacial melt.
Glacial alpine lakes differ from other glacier-formed lakes in that they occur at higher altitudes and mountainous terrain usually at or above timberline. For example, the Great Lakes of the U.S. and Canada are formed by the retreat of the Laurentide Ice Sheet during the last Ice Age which scoured the flat rock surface but are not in the alpine. Conversely, Lake Louise located in the Rocky Mountains was formed from glacial debris damming meltwater (i.e., a moraine lake) from the Victoria Glacier.
Stratification
The annual cycle of stratification and mixing in lakes plays a significant role in determining vertical distribution of heat, dissolved chemicals, and biological communities. Most alpine lakes exist in temperate or cold climates characteristic of their high elevation, leading to a dimictic mixing regime. Dimictic lakes fully mix twice a year between periods of vertical stratification in the summer and winter. Summer stratification is caused by heating of surface waters, and winter stratification is caused by cooling of surface waters below the freshwater temperature of maximum density (approximately ). Seasonal ice cover reinforces the dimictic stratification cycle of alpine lakes by insulating the lake from wind and warm air in the spring when stratification is generally weaker. Some shallow alpine lakes can become fully mixed multiple times per year through episodic wind or cold inflow events and are therefore considered cold polymictic. A number of meromictic alpine lakes (in which a deep layer of the lake never mixes with surface water) exist. Lake Cadagno, located in the Swiss Alps, is meromictic due to natural springs which constantly feed the bottom of the lake with dense, saline water. Other alpine lakes, such as Traunsee in Austria, have become meromictic due to salinization from anthropogenic activities such as mining.
Recent studies suggest that climate change may impact the annual cycles of stratification in alpine lakes. High altitude regions are experiencing changing seasonal weather patterns and faster warming than the global average. The duration of ice cover on alpine lakes is sensitive to these factors, and shorter ice cover duration has the potential to shift the mixing regime of lakes from dimictic to monomictic (one stratified and one fully mixed period each year). A change in mixing regime could fundamentally alter chemical and biological conditions such as nutrient availability and the timing and duration of hypoxia in alpine lakes. In addition, the relatively small size and high altitude of alpine lakes may make them especially susceptible to changes in climate.
Hydrology
The hydrology of an alpine lake's watershed plays a large role in determining chemical characteristics and nutrient availability. Sources of water inflow into alpine lakes include precipitation, melting snow and glaciers, and groundwater. Alpine lake inflow often has a large seasonal cycle due to precipitation falling as snow and low glacier melt over the watershed in the winter contrasted with rainfall and increased glacier melt in summer. Alpine lakes are often situated in mountainous regions near or above the treeline which leads to steep watersheds with underdeveloped soil and sparse vegetation. A combination of cold climate over alpine watersheds, shading from steep topography, and low nutrient concentrations in runoff make alpine lakes predominantly oligotrophic.
Different watershed characteristics create a distinction between clear alpine lakes and glacier-fed alpine lakes (lakes with inflow from melting glaciers). Clear alpine lakes have low concentrations of suspended sediment and turbidity which can be caused by a lack of erosion in the watershed. Glacier-fed lakes have much higher suspended sediment concentrations and turbidity due to inflow of glacial flour, resulting in opaqueness and a bright blue or brown color. The turbidity of alpine lakes plays a significant role in determining light availability for primary productivity and is heavily dependent on each lake's unique watershed.
Circulation
Circulation in alpine lakes can be caused by wind, river inflows, density currents, convection, and basin-scale waves. Steep topography characteristic of alpine lakes can partially shield them from wind generated by regional weather patterns. Therefore, smaller scale wind patterns generated by local topography, such as diurnal mountain breeze and katabatic wind, can be important in forcing circulation in alpine lakes. Wind patterns which vary spatially over the extent of the lake may create regions of upwelling and downwelling. River inflow can induce circulation in alpine lakes through momentum carried directly into the lake by rivers or streams and through density currents. If the inflowing water is denser than the water at the surface of the lake (due to differences in temperature or sediment concentration), buoyancy drives the heavier inflowing water down the slope of the lake bed or into the lake interior. Such density-driven flows have been recorded in alpine lakes with velocities reaching nearly 1 m/s. Heating and cooling of alpine lakes can cause surface waters to become more dense than the water in the interior of the lake. This results in a gravitationally unstable water column, and the dense water is pulled downward from the surface causing convection. This vertical circulation is an efficient means for mixing in lakes and may play a significant role in homogenizing the water column between periods of stratification. Basin-scale waves, such as internal waves and seiches, can also drive circulation in alpine lakes. Internal seiches in an alpine lake have been observed with attendant velocities on the order of a few centimeters per second.
Ecology
Microbial community structure
Alpine lakes are home to a unique diversity of invertebrates that are highly adapted to the colder and generally harsher conditions of these environments compared to lakes at lower altitudes. A few dominating species have adapted to the oligotrophic conditions and intense UV radiation, with chironomidae and oligochaeta comprising almost 70% of the community in two well-studied alpine lakes in northern Italy, and also the two most prominent species (66% and 28%, respectively) in 28 alpine lakes in Austria. Phytoplankton populations are dominated by nanoplanktonic, mobile species including chrysophytes, dinoflagellates, and cryptophytes in the water column, with important contributions to photosynthesis also coming from the algae community attached to substrates, epilithon and epipelon. Viruses are also observed in alpine lakes at abundances of up to 3 x 107 ml−1, which nears the upper range of the general observed abundances from 105 to 108 ml−1 in aquatic systems.
A study of 28 alpine lakes found that with increasing elevation, macroinvertebrate abundances increase in small lakes but decrease in larger lakes and community composition shifts with increasing elevation, towards a small number of specialized species. The increasing abundances in smaller lakes as elevation increases are thought to be due to the more extreme temperature regimes characteristic of smaller bodies of water, selecting for a small subset of more robust species that end up thriving from less overall competition. Altitude may also affect community composition due to the change in availability of food resources. For example, at higher altitudes, alpine lakes experience shorter ice-free periods which places a limit on the amount of primary production and subsequent growth of food. In conclusion, both the lake's physical features, including size and substrate, and environmental parameters, including temperature and ice-cover, define community composition and structure, with one study suggesting that temperature and altitude are the primary drivers, and another presenting evidence instead for heterogeneity in lake morphometry and substrate as the primary drivers. The latter, in particular an increase in rocky substratum, was found to negatively impact abundance and species richness. All of these environmental parameters are likely to be impacted by climate change, with cascading effects on alpine lake invertebrate and microbial communities.
Vertebrate community structure
The vertebrate community of alpine lakes is much more limited than invertebrate communities as harsh conditions have an increased impact on the organisms, but can include fish, amphibians, reptiles, and birds. Despite this, many alpine lakes can still host diverse species at these high elevations. These organisms have arrived in several ways through human introductions, ecological introductions, and some are endemic to their respective lakes. The Titicaca water frog in Lake Titicaca in the high Andes is one species that is endemic, while others were introduced.
Lake Titicaca is home to a wide variety of vertebrates, including the Titicaca water frog (Telmatobious culeous), and the endangered Titicaca grebe (Rollandia microptera) found only in the Titicaca basin. The basin is also home to a variety of bird species and is considered a Ramsar Site due to its ecological importance. Waterbird species include Chilean flamingo, greater yellowlegs, snowy egret, Andean coot, Andean gull, and the Andean lapwing.
Another important alpine lake, Crater Lake located in Oregon, is home to several introduced fish species, native amphibians, and reptiles. The amphibians and reptiles that can be found in Crater Lake are the mazama newt, northwestern salamander, northwestern ribbed frog, northwestern toad, cascade frog, pacific tree frog, northern mountain lizard, pigmy horned toad, northern alligator lizard, and northwestern garter snake.
Introduced species
Some alpine lakes do not hold any native vertebrate species and instead have grown their vertebrate communities through introduced species. Fish are commonly introduced by humans stocking lakes for recreational and competitive fishing.
Crater Lake did not hold any vertebrate species before a stocking event between 1884 and 1941 of 1.8 million salmonids, mainly Rainbow trout (Oncorhynchus mykiss) and kokanee salmon (O. nerka). Other species introduced included brown trout (Salmo trutta), coho salmon (O. kisutch), cutthroat trout (O. clarkii), and steelhead salmon (O. mykiss). Introduced fish impact the limnetic and benthic communities, as they are the primary prey of non-native fish. Salamanders and newts found at Crater Lake also experienced encroachment on their native habitats and have been reduced or eliminated in numbers. These amphibians were also found in the stomach contents of fish stocked in Crater Lake, which has further reduced populations.
Lake Tahoe, located between California and Nevada, also has several introduced fish species established in the basin due to recreational fishing, including lake trout (Salvelinus namaycush), rainbow trout, brown trout, bluegill (Lepomis macrochirus), carp (Cyprinus caprio), and others. Lake trout, along with an introduced freshwater shrimp, Mysis relicta, have drastically changed the food web in Lake Tahoe. Nearby Cascade Lake in California, which is often closely studied with Lake Tahoe, does not have any introduced species due to highly restricted public access. Fish were also stocked in Lake Titicaca following the decimation of a native fish population after a fishing competition.
Some studies have noted that recreational fishing of introduced species in alpine lakes may have negative effects on the overall ecosystem. Bringing in non-native species, especially to fishless lakes, can also carry pathogens and bacteria, negatively impacting the invertebrate community already there. Studies of two fishless Italian alpine lakes, Dimon Lake and Balma Lake, found that introduced fish brought new viruses and bacteria that were harmful to the native amphibians in the water. The studies also showed that the only way to fix the problem is to completely eradicate the non-native fish species in the lakes in any way possible. These included using gill nets, electrofishing, and continued aggressive recreational fishing.
Climate change impacts
Alpine lake invertebrates are arguably one of the most vulnerable communities of invertebrates to increasing temperatures associated with human-induced climate change, due to the expected increase in ice-free periods and to the relatively small impact of human-changed land cover that other similar terrestrial-aquatic systems have already been subjected to. Cold-stenothermal species uniquely adapted to survive in only a small range of cold temperatures, and larger sexual reproducing species slower to reproduce than smaller, asexual species under perturbations, could both be negatively impacted. Melting glaciers are presumed to increase the sizes of the alpine lakes that are glacier-fed, impacting the evidence size effect on community composition. Also, habitat structure could change in response to an increase in erosion from thawing permafrost, and lastly, an uptick in the frequency and magnitude of extreme weather events would increase water column turbidity, which is well-known to impact the processes of photosynthesis and respiration by increasing light attenuation and decreasing the size of the photic zone. Alpine lake ecosystems are undergoing unprecedented rates of change in community composition in relation to recent temperature increases and nutrient loading. Consistent monitoring can help identify, quantify and characterize this ecological impact.
One such monitoring technique employs macroinvertebrates as bioindicators primarily to analyze the accumulation of trace elements associated with pollution and to, more generally, track changes in biological communities due to climate change. Trace elements can occur naturally, but industrialization, including the consumption of fossil fuels, has accelerated their rate of accumulation into alpine lake environments. Though essential to life in low concentrations, some trace elements begin to function as contaminants with over-accumulation. After being released into the atmosphere, trace elements can become soluble through biogeochemical processes and end up in sediment and then mobilized through weathering and runoff to enter alpine lake ecosystems. Benthic macroinvertebrates often at the base of food webs, are the primary accumulators of trace elements, which are then transferred up the food chain to fish or birds via predation. The seminal study that used chironomids as bioindicators due to their abundance in alpine lakes and variety of feeding habits (collectors, shredders, and predators) found that most trace element concentrations are within limits of sediment quality targets, with the exception of lead in both study lakes and zinc in one, and also concluded that trace element concentrations reflected the relative levels of pollution impacting each alpine lake in the study region of northern Italy. Another study, upon assessing the composition through time of chosen bioindicators and finding evidence for degraded water quality, concluded that the lake ecosystem had moved out of a "safe operational state".
Alkalinity and pH
Alkalinity can be defined as the acid neutralizing capability of a body of water. Alkalinity in natural waters is largely due to bicarbonate, the strong conjugate base of the weak carbonic acid, that is the product of rock weathering. Bicarbonate has the ability to act as an acid or a base in water, making it a buffer to resist change from acidic or basic inputs into a body of water. Alkalinity is measured in the unit μeq L−1 which is determined by the concentration of an ion per liter of water multiplied by the charge of the ion or by titration.
Alpine lakes have been well studied in regard to acidification since the 1980s largely because of the seasonal patterns of alkalinity and pH changes that they naturally exhibit from precipitation and snowmelt. These lakes experience seasonally low alkalinity (and thus low pH), making them highly susceptible to acid precipitation as a result of atmospheric pollutants. The water chemistry of alpine lakes is dominated by atmospheric deposition (transport of particles between the atmosphere) and catchment processes (drainage of precipitation). The weather patterns of alpine lakes include large periods of snowmelt which has extended contact with soil and rock resulting in increased alkalinity. Weathering of rocks that are calcareous or carbonate based (limestone) are the major contributors of alkalinity to alpine lakes whereas alpine lakes in regions of granite and other igneous rocks have lower alkalinity due to slower kinetics of the weathering. Lower alkalinity indicates a lower ability to buffer the water from acidic or basic inputs so alpine lakes with low alkalinity are susceptible to acidic pollutants in the atmosphere. It is generally accepted that alpine lakes with alkalinity less than 200 unit μeq L−1 are susceptible to acidification.
European Alps
The Alps are the largest mountain range in Europe and home to some of the most well-known lakes. The bedrock in the Alps varies greatly and can be composed of granite, quartz, slate, dolomite, marble, limestone and much more. This diverse geological structure plays a role in the diverse alkalinity of each alpine lake. A study of 73 alpine lakes in the Eastern Alps determined that 85% of the lakes had low alkalinity values (< 200 μeq L−1) with only two lakes having an alkalinity above 500 μeq L−1. This study also determined pH and found a range from 7.93–4.80 with 21% of the lakes having a pH below 6.00. The pH in this region was also found to be independent of altitude.
A similar analysis was done on 207 lakes, resulting in an alkalinity range from -23 to 1372 μeq L−1 and an average of 145 μeq L−1. The pH was also determined for these lakes, ranging from 4.6 to 9.2. Alpine lakes with a pH less than 6.0 had shown acidic effects on micro-organisms and a pH less than 5.3 was characterized as having reached severe acidification. This analysis was repeated on 107 alpine lakes in the Central Alps with bedrock of silicic and ultrabasic rocks. These lakes had an alkalinity range from 155 to -23 microequiavlents per liter, suggesting how sensitive alpine lakes with similar bedrock might be to acidic rain.
Cascade Range
The Cascade Mountain Range extends from Northern California through Oregon and Washington. This region is composed of sedimentary and volcanic rocks, has heavy seasonal precipitation, and coniferous forests. The Alpine Lakes Wilderness Area in the Washington Cascades has over 700 lakes. Alkalinity for lakes in the Cascade region vary from as high as 400 μeq L-1 to as low as 57 μeq L−1, all of which are considered to be low alkalinity, and suggestive that they might be susceptible to acidification. The pH of these lakes ranged from 7.83 to 5.62, and in this region an acidified lake is considered having a pH below 4.7. The Cascade Range was further evaluated by subregions since the environments vary greatly. Lower alkalinity, 50–100 μeq L−1, was observed in regions with little soil and granite rocks, like that of Glacier Peak Wilderness and Mt. Rainier. Higher alkalinity, 200–400 μeq L−1, was observed in regions composed of basalt and andesite such as the Western Cascades.
Palaeoclimatological data
Paleoproxies are chemical or biological sources that serve as indicator data for some aspect of the climate and can help reconstruct past regional climates and the future fate of alpine environments. Alpine lakes themselves are unique reservoirs of paleoclimate data, particularly for understanding climate in the late Quaternary, as they collect and store geomorphological and ecological data in their sediment. These records of the past allow for a better understanding of how alpine lakes have responded to climate variability. Thus, by understanding these mechanisms of the past, better predictions can be made about the future response of alpine ecosystems to present-day climate change.
The fraction of mineral phosphorus (P) to organic P within lake sediments can be used to determine if the sediment deposits are sourced from glaciers (higher mineral to organic P ratio) or debris slopes (lower mineral to organic P ratio). Therefore, the sediment P content can inform glacial activity and thus climate at the time the sediment was deposited. For instance, an alpine lake in the Coast Mountains of British Columbia revealed cooler and wetter conditions due to the increased trend in mineral-rich (glacial-derived) P sediments which agrees with other findings of cooling in the Holocene.
Magnetic properties of the sediment in alpine lakes can also help infer glacial activity at a high resolution. When the magnetic properties of the lake sediments match those of the bedrock, it can be deduced that there was more glacier movement, i.e., cooler temperatures. Along with the sediments being "detrital" (bedrock weathering), the sediments are more coarse-grained indicating high glacial activity associated with the Pleistocene.
Diatom assemblages reveal changes in benthic conditions and alkalinity which help infer changes in temperature and carbon dioxide concentrations over time. During periods of warmer temperatures, extended growing seasons led to more benthic plant growth which is revealed by more periphytic (substrate-growing) diatom species. After the onset of the Industrial Revolution, diatom assemblages revealed more acidic conditions which are associated with higher carbon dioxide concentrations. Aside from the alpine lakes themselves serving as a source of paleoclimate observations, the surrounding alpine zone also contributes many useful proxies such as tree ring dynamics and geomorphological features.
| Physical sciences | Hydrology | Earth science |
69445009 | https://en.wikipedia.org/wiki/Ocean%20surface%20ecosystem | Ocean surface ecosystem | Organisms that live freely at the ocean surface, termed neuston, include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, marine snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston. Species at the surface are not distributed uniformly; the ocean's surface provides habitat for unique neustonic communities and ecoregions found at only certain latitudes and only in specific ocean basins. But the surface is also on the front line of climate change and pollution. Life on the ocean's surface connects worlds. From shallow waters to the deep sea, the open ocean to rivers and lakes, numerous terrestrial and marine species depend on the surface ecosystem and the organisms found there.
The ocean's surface acts like a skin between the atmosphere above and the water below, and hosts an ecosystem unique to this environment. This sun-drenched habitat can be defined as roughly one metre in depth, as nearly half of UV-B is attenuated within this first meter. Organisms here must contend with wave action and unique chemical and physical properties. The surface is utilised by a wide range of species, from various fish and cetaceans, to species that ride on ocean debris (termed rafters).
Most prominently, the surface is home to a unique community of free-living organisms, termed neuston (from the Greek word υεω, which means both to swim and to float). Floating organisms are also sometimes referred to as pleuston, though neuston is more commonly used. Despite the diversity and importance of the ocean's surface in connecting disparate habitats, and the risks it faces, not a lot is known about neustonic life.
Overview
Neuston are key ecological links connecting ecosystems as far ranging as coral reefs, islands, the deep sea, and even freshwater habitats. In the North Pacific, 80% of the loggerhead turtle diet consists of neuston prey, and nearly 30% of the Laysan albatross's diet is neuston. Diverse pelagic and reef fish species live at the surface when young, including commercially important fish species like the Atlantic cod, salmon, and billfish. Neuston can be concentrated as living islands that completely obscure the sea surface, or scattered into sparse meadows over thousands of miles. Yet the role of the neuston, and in many cases their mere existence, is often overlooked.
One of the most well-known surface ecoregions is the Sargasso Sea, an ecologically distinct region packed with thick, neustonic brown seaweed in the North Atlantic. Multiple ecologically and commercially important species depend on the Sargasso Sea, but neustonic life exists in every ocean basin and may serve a similar, if unrecognised, role in regions across the planet. For example, over 50 years ago, USSR scientist A. I. Savilov characterised 7 neustonic ecoregions in the Pacific Ocean. Each ecoregion possesses a unique combination of biotic and abiotic conditions and hosts a unique community of neustonic organisms. Yet these ecoregions have been largely forgotten.
But there is another reason to study neuston: The ocean's surface is on the front line of human impacts, from climate change to pollution, oil spills to plastic. The ocean's surface is hit hard by anthropogenic change, and the surface ecosystem is likely already dramatically different from even a few hundred years ago. For example, prior to widespread damming, logging, and industrialisation, more wood may have entered the open ocean, while plastic had not yet been invented. And because floating life provides food and shelter for diverse species, changes in the surface habitat will cause changes in other ecosystems and have implications that are not currently fully understand or be able to be predicted.
Ocean surface life (neuston)
Invoking images of the open ocean's surface, the imagination can conjure up an endless empty space. A flat line parting the blue below from the blue above. But in reality a diverse array of species occupy this unique boundary layer. A tangle of terms exist for different organisms occupying different niches of the ocean's surface. The most inclusive term, neuston, is used here to refer to all of them.
Neustonic animals and plants live hanging from the surface of the ocean as if suspended from the roof of a massive cave, and are incapable of controlling their direction of movement. They are considered permanent residents of the surface layer. Many genera are globally distributed. Many organisms have morphological features that enable them to remain at the ocean's surface, with the most noticeable adaptations being floats.
Floaters (pleuston)
Epineuston
Hyponeuston
Rafting organisms
Surface microlayer
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of the Earth's surface. With an operationally defined thickness between 1 and 1000 μm, the SML has physicochemical and biological properties that are measurably distinct from underlying waters. Recent studies now indicate that the SML covers the ocean to a significant extent, and evidence shows that it is an aggregate-enriched biofilm environment with distinct microbial communities. Because of its unique position at the air-sea interface, the SML is central to a range of global biogeochemical and climate-related processes.
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of the Earth's surface. The SML has physicochemical and biological properties that are measurably distinct from underlying waters. Because of its unique position at the air-sea interface, the SML is central to a range of global biogeochemical and climate-related processes. Although known for the last six decades, the SML often has remained in a distinct research niche, primarily as it was not thought to exist under typical oceanic conditions. Recent studies now indicate that the SML covers the ocean to a significant extent, highlighting its global relevance as the boundary layer linking two major components of the Earth system – the ocean and the atmosphere.
In 1983, Sieburth hypothesised that the SML was a hydrated gel-like layer formed by a complex mixture of carbohydrates, proteins, and lipids. In recent years, his hypothesis has been confirmed, and scientific evidence indicates that the SML is an aggregate-enriched biofilm environment with distinct microbial communities. In 1999 Ellison et al. estimated that 200 Tg C yr−1 accumulates in the SML, similar to sedimentation rates of carbon to the ocean's seabed, though the accumulated carbon in the SML probably has a very short residence time. Although the total volume of the microlayer is very small compared to the ocean's volume, Carlson suggested in his seminal 1993 paper that unique interfacial reactions may occur in the SML that may not occur in the underlying water or at a much slower rate there. He therefore hypothesised that the SML plays an important role in the diagenesis of carbon in the upper ocean. Biofilm-like properties and highest possible exposure to solar radiation leads to an intuitive assumption that the SML is a biochemical microreactor.
Historically, the SML has been summarized as being a microhabitat composed of several layers distinguished by their ecological, chemical and physical properties with an operational total thickness of between 1 and 1000 μm. In 2005 Hunter defined the SML as a "microscopic portion of the surface ocean which is in contact with the atmosphere and which may have physical, chemical or biological properties that are measurably different from those of adjacent sub-surface waters". He avoids a definite range of thickness as it depends strongly on the feature of interest. A thickness of 60 μm has been measured based on sudden changes of the pH, and could be meaningfully used for studying the physicochemical properties of the SML. At such thickness, the SML represents a laminar layer, free of turbulence, and greatly affecting the exchange of gases between the ocean and atmosphere. As a habitat for neuston (surface-dwelling organisms ranging from bacteria to larger siphonophores), the thickness of the SML in some ways depends on the organism or ecological feature of interest. In 2005, Zaitsev described the SML and associated near-surface layer (down to 5 cm) as an incubator or nursery for eggs and larvae for a wide range of aquatic organisms.
Hunter's definition includes all interlinked layers from the laminar layer to the nursery without explicit reference to defined depths. In 2017, Wurl er al. proposed Hunter's definition be validated with a redeveloped SML paradigm that includes its global presence, biofilm-like properties and role as a nursery. The new paradigm pushes the SML into a new and wider context relevant to many ocean and climate sciences.
According to Wurl et al.m the SML can never be devoid of organics due to the abundance of surface-active substances (e.g., surfactants) in the upper ocean and the phenomenon of surface tension at air-liquid interfaces. The SML is analogous to the thermal boundary layer, and remote sensing of the sea surface temperature shows ubiquitous anomalies between the sea surface skin and bulk temperature. Even so, the differences in both are driven by different processes. Enrichment, defined as concentration ratios of an analyte in the SML to the underlying bulk water, has been used for decades as evidence for the existence of the SML. Consequently, depletions of organics in the SML are debatable; however, the question of enrichment or depletion is likely to be a function of the thickness of the SML (which varies with sea state; including losses via sea spray, the concentrations of organics in the bulk water, and the limitations of sampling techniques to collect thin layers . Enrichment of surfactants, and changes in the sea surface temperature and salinity, serve as universal indicators for the presence of the SML. Organisms are perhaps less suitable as indicators of the SML because they can actively avoid the SML and/or the harsh conditions in the SML may reduce their populations. However, the thickness of the SML remains "operational" in field experiments because the thickness of the collected layer is governed by the sampling method. Advances in SML sampling technology are needed to improve our understanding of how the SML influences air-sea interactions.
Surface slicks
Slicks are meandering lines of smooth water on the ocean surface that are ubiquitous coastal features around the world. A variety of mechanisms can cause slick formation, including tidal and headland fronts, and as a consequence of subsurface waves called internal waves. Internal wave slicks are generated when internal waves interact with steep seafloor topography and drive areas of convergence and divergence at the ocean surface. The build-up of organic material (surfactants) at the surface modifies surface tension causing a smooth, oil slick-like appearance. The convergent flow can accumulate dense aggregations of plankton including larval fish and invertebrates at or below the ocean surface.
Surface slicks are the focal point for numerous trophic and larval connections that are foundational for marine ecosystem function. Life for many marine organisms begins near the ocean surface. Buoyant eggs hatch into planktonic larvae that develop and disperse in the ocean for weeks to months before transitioning into juveniles and eventually finding suitable adult habitat. The pelagic larval stage connects populations and serves as a source of new adults. Oceanic processes affecting the fate of larvae have profound impacts on population replenishment, connectivity, and ecosystem structure. Although it is an important life stage, there is, as of 2021, limited knowledge of the ecology and behaviour of larvae. Understanding the biophysical interactions that govern larval fish survival and transport is essential for predicting and managing marine ecosystems, as well as the fisheries they support.
The diagram shows: (1) Larval and juvenile stages of fishes from many ocean habitats aggregate in slicks in order to capitalize on dense concentrations of prey (2, phytoplankton, 3, zooplankton, 4, larval invertebrates, 5, eggs, and 6, insects). The increased predator–prey overlap in slicks increases energy flow that propagates up the food-web (dotted blue lines show trophic links), enhancing energy available to higher trophic level predators (icons outlined in blue) including humans. More than 100 species of fishes develop and grow in surface slick nurseries before transitioning to adults (solid white lines radiating outward) in Coral Reefs (7–12), Epipelagic (13–15), and Deep-water (16–17) ocean habitats. As adults these taxa (icons outlined in white) play important ecological functions and provide fisheries resources to local human populations. For example, coastal schooling fishes (7, mackerel scad) are important food and bait fish for humans. Planktivorous fish (8, some damselfishes and triggerfishes) transfer energy from zooplankton up to reef predators like jacks (9), which provide top-down control of reefs and are important targets for shoreline recreational fisherfolk. Grazers (10, chubs) help keep coral reefs from being overgrown by macroalgae. Cryptobenthic fishes such as blennies (11) and benthic macrocrustaceans (12, shrimp, stomatopods, crabs) comprise most of the consumed biomass on reefs. In the pelagic ocean, flyingfishes (13) channel energy and nutrients from zooplankton to pelagic predators such as mahi-mahi (14) and billfish (15), both of which utilize slicks as nursery habitat. Larvae of mesopelagic fishes like lanternfish (16) and bathydemersal tripod fishes (17) utilize these surface hotspots before descending to deep-water adult habitat.
The distribution of prey and predators in the ocean is patchy. Larval survival depends on prey availability, predation, and transport to suitable habitat, all of which are influenced by ocean conditions. Ocean processes that drive convergent flow such as fronts, internal waves, and eddies, can structure plankton, enhance overlap of predators and prey, and influence larval dispersal. Convergent features can also lead to a cascade of effects that ultimately drive food web structure and increase ecosystem productivity.
Life history
Life histories connect disparate ecosystems; species that live at the surface during one life history stage may occupy the deep sea, benthos, reefs, or freshwater ecosystems during another. A diversity of fish species utilize the ocean's surface, either as adults or as nursery habitat for eggs and young. In contrast, species floating on the ocean's surface during one life cycle stage often (though not always) have pelagic larval stages. Velella and Porpita release jellyfish (medusae), and while little is known about Porpita medusae, Velella medusae could possibly sink into deeper water, or remain near the surface, where they derive nutrients from zooxanthellae. Janthina have pelagic veliger larvae, and Physalia may release reproductive clusters that drift in the water column. Halobates lay eggs on a variety of objects, including floating objects and pelagic snail shells.
All species with pelagic stages must eventually find their way back to the surface. For Velella and Porpita, larvae generated by sexual reproduction of medusae develop small floats, which carry them to the surface. For the larvae of Janthina, the transition to surface life includes the degradation of their eyes and vestibule system, and at the same time, the production of an external structure, which has been reported as either a small parachute made of mucus, or a cluster of bubbles, which they ride to the surface. Young Halobates may hatch either above or below the surface, and for those below, the surface tension proves a formidable barrier. It may take Halobates nymphs several hours to break through the surface film. Despite the challenges of reaching the surface, there may be benefits to a temporary pelagic life.
Connectivity of ocean surface ecosystems may be facilitated by the life history of species living there. One hypothesis is that species have pelagic stages to "escape" surface sink regions and repopulate surface source regions, where one life cycle stage drifts on surface currents in one direction, and a pelagic stage either remains geographically localised or drifts in the opposite direction. However, some surface species, such as the endemic species of the Sargasso Sea, may remain geographically isolated throughout their life history. While these hypotheses are intriguing, it is not known if or how life history shapes population/species distribution for most neustonic species. Understanding how life history varies by species is a critical component of assessing both connectivity and conservation of neustonic ecosystems.
Sea spray
A stream of airborne microorganisms circles the planet above weather systems but below commercial air lanes. Some peripatetic microorganisms are swept up from terrestrial dust storms, but most originate from marine microorganisms in sea spray. In 2018, scientists reported that hundreds of millions of viruses and tens of millions of bacteria are deposited daily on every square meter around the planet.
These airborne microorganisms form part of the aeroplankton. The aeroplankton are tiny lifeforms that float and drift in the air, carried by the current of the wind; they are the atmospheric analogue to oceanic plankton. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of their tiny size. Scientists collect them for study in traps and sweep nets from aircraft, kites or balloons.
The environmental role of airborne cyanobacteria and microalgae is only partly understood. While present in the air, cyanobacteria and microalgae can contribute to ice nucleation and cloud droplet formation. Cyanobacteria and microalgae can also impact human health. Depending on their size, airborne cyanobacteria and microalgae can be inhaled by humans and settle in different parts of the respiratory system, leading to the formation or intensification of numerous diseases and ailments, e.g., allergies, dermatitis, and rhinitis.
| Physical sciences | Oceanography | Earth science |
69453546 | https://en.wikipedia.org/wiki/Basset | Basset | Bassets are a sub-type of scenthound deliberately bred with short legs, that are used for hunting where the hunters accompany the hunting hounds on foot.
History
Bassets were originally developed in France from where they spread throughout Europe and the world. The name basset is derived from the French word bas which means low, a reference to their stature. It is believed bassets were bred from Saint Hubert-type hounds, with breeders taking advantage of a genetic mutation resulting in short legs to develop smaller statured, deep scenting hounds. These short-legged hounds were deliberately bred to allow hunters to accompany the hunting hounds on foot, as opposed to following hunt from horseback; their smaller stature making them slower and so easier to keep up with on foot.
The first description of bassets was in the 16th century by Jacques du Fouilloux in his work La vénerie, stating they were found in the regions of Artois and Flanders. Du Fouilloux described two types of bassets; the first were short-coated with crooked forelegs and were used to hunt above ground as well as to pursue game below ground; the second were often rough-coated with straighter forelegs and only pursued game above ground. Hunting game on foot with bassets experienced a rapid increase in popularity in France after the French Revolution in the late 18th century, when hunting with large hounds from horseback was almost eliminated in France as it was traditionally the preserve of the nobility.
Description
Bassets have a strong resemblance to larger, longer-legged hound breeds, particularly the Bloodhound, despite their much smaller stature. Bassets’ forelegs tend to be either crooked or straight, depending upon the breed; the coat types and colours seen within different basset breeds reflect those seen within the broader scenthound type, with short, long and wiry coats all found.
Use
Bassets hunt in packs and traditionally are used to hunt in two ways; in the first the hounds trail their quarry noisily to waiting hunters with guns who shoot the game; in the second the hounds pursue the quarry until they catch it. Packs of bassets are still used to hunt various quarry, particularly hare and rabbit, but they are also used to flush gamebirds in a similar manner to spaniels.
Breeds
Recognised breeds of basset include the French Basset Artésien Normand, Basset Bleu de Gascogne, Basset Fauve de Bretagne, Grand Basset Griffon Vendéen and Petit Basset Griffon Vendéen and the Basset Hound from Great Britain.
Other non-French origin breeds often considered basset-adjacent include the Alpine Dachsbracke from Austria, the Berner Niederlaufhund, Jura Niederlaufhund, Luzerner Niederlaufhund and Schwyzer Niederlaufhund from Switzerland, the Drever from Sweden, and the Westphalian Dachsbracke from Germany.
| Biology and health sciences | Dogs | Animals |
68106647 | https://en.wikipedia.org/wiki/Neogale | Neogale | Neogale (colloquially referred to as the New World weasels) is a genus of carnivorous, highly active small mammals belonging to the Mustelidae family (which also contains badgers, weasels, martens, otters, and wolverines, among others). Native to the Americas, members of the genus can be found as far north as Alaska and as far south as Argentina and Bolivia. Across this distribution, they thrive in a range of habitats, from the deep-freezes of the Alaskan and Canadian boreal forests to the arid desert southwest, and from the humid tropics of Central and South America (including the Amazon basin) to the windswept foothills of the Andes and northern Patagonia.
Taxonomy
Members of this genus were formerly classified into the genera Mustela and Neovison, but many studies had previously recovered several American species of Mustela, as well as both species within Neovison, to comprise a monophyletic clade distinct from all other members of Mustelinae. A 2021 study found this clade to have diverged from Mustela during the Late Miocene, between 11.8 - 13.4 million years ago, with all members within the clade being more closely related to one another than to any of the other species in Mustela, and gave it the name Neogale, originally coined by John Edward Gray. The American Society of Mammalogists later accepted this change.
Species
There are 5 recent species in the genus, 4 extant and 1 extinct:
Extant species
Extinct species
| Biology and health sciences | Mustelidae | Animals |
63871781 | https://en.wikipedia.org/wiki/System%20of%20differential%20equations | System of differential equations | In mathematics, a system of differential equations is a finite set of differential equations. Such a system can be either linear or non-linear. Also, such a system can be either a system of ordinary differential equations or a system of partial differential equations.
Linear systems of differential equations
A first-order linear system of ODEs is a system in which every equation is first order and depends on the unknown functions linearly. Here we consider systems with an equal number of unknown functions and equations. These may be written as
where is a positive integer, and are arbitrary functions of the independent variable t. A first-order linear system of ODEs may be written in matrix form:
or simply
.
Homogeneous systems of differential equations
A linear system is said to be homogeneous if for each and for all values of , otherwise it is referred to as non-homogeneous. Homogeneous systems have the property that if are linearly independent solutions to the system, then any linear combination of these, , is also a solution to the linear system where are constant.
The case where the coefficients are all constant has a general solution: , where is an eigenvalue of the matrix with corresponding eigenvectors for . This general solution only applies in cases where has n distinct eigenvalues, cases with fewer distinct eigenvalues must be treated differently.
Linear independence of solutions
For an arbitrary system of ODEs, a set of solutions are said to be linearly-independent if:
is satisfied only for .
A second-order differential equation may be converted into a system of first order linear differential equations by defining , which gives us the first-order system:
Just as with any linear system of two equations, two solutions may be called linearly-independent if implies , or equivalently that is non-zero. This notion is extended to second-order systems, and any two solutions to a second-order ODE are called linearly-independent if they are linearly-independent in this sense.
Overdetermination of systems of differential equations
Like any system of equations, a system of linear differential equations is said to be overdetermined if there are more equations than the unknowns. For an overdetermined system to have a solution, it needs to satisfy the compatibility conditions. For example, consider the system:
Then the necessary conditions for the system to have a solution are:
| Mathematics | Differential equations | null |
66693032 | https://en.wikipedia.org/wiki/Land%20change%20science | Land change science | Land change science refers to the interdisciplinary study of changes in climate, land use, and land cover. Land change science specifically seeks to evaluate patterns, processes, and consequences in changes in land use and cover over time. The purpose of land change science is to contribute to existing knowledge of climate change and to the development of sustainable resource management and land use policy. The field is informed by a number of related disciplines, such as remote sensing, landscape ecology, and political ecology, and uses a broad range of methods to evaluate the patterns and processes that underlie land cover change. Land change science addresses land use as a coupled human-environment system to understand the impacts of interconnected environmental and social issues, including deforestation and urbanization.
History
Land change science is a recently developed field, which emerged in conjunction with the advancement of climate change and global environmental change research, and is important to the evolution of climate change science and adaptation. It is both problem-oriented and interdisciplinary. In the mid-20th century, human-environment relationships were emerging in areas of study such as anthropology and geography. Some scholars assert that the discipline of land change science is loosely derived from German concepts of landscape as the total amount of things within a given territory. In the latter half of the 20th century, scientists studying cultural ecology and risk-assessment ecology worked to develop land change science as a means of addressing land as a human-environment system that can be understood as a foundation of global environmental science.
Aims
Thus far, the aims of land change science have been to:
Observe and monitor land changes underway throughout the world
Understand land change as a human-environmental system
Model land change
Assess system outcomes such as vulnerability, sustainability, and resilience
Related disciplines
Land change science is an interdisciplinary field, and thus is influenced by a number of related areas of study, including remote sensing, political ecology, resource economics, landscape ecology, and biogeography. It is meant to supplement the study of climate change, and through the examination of land cover and land use changes in conjunction with climatic changes over the same period of time, scientists can better understand how human land use practices contribute to a changing climate. Given its close association with the study of climate change, land change science is inherently sustainability research and the scientific knowledge it produces is used to influence the development of sustainable agriculture, and sustainable land use practices and policies.
Although land change science involves quantifying the location, extent, and variability of land change cover and the analysis of emergent patterns, it remains fundamentally interdisciplinary, including social and economic components.
Methods
Land change science mainly operates within the international scientific research frameworks from which its fundamental questions were developed. Although the field has ties to social and cultural studies in its understanding of land and land change as a human-environment system, land change science also focuses on ecosystems and earth systems' structure, function, and effects on land change, independent of human activity. Land change science encompasses a broad scope of dimensions, ranging from quantifying the ecological effects of land cover change, to understanding the socio-environmental drivers for land-use decisions at an institutional level. As a result, land change science relies on the synthesis of a wide range of data and a diverse range of data collection methods. These include for example land cover monitoring and assessments, modeling risk and vulnerability, and land change modeling.
Challenges
Land change science as a discipline faces several challenges, many of the stemming from its interdisciplinary qualities or issues with developing inferences using aggregate data. For example, land change science is limited by constraints on data and lack of understanding of underlying issues of land change. Specifically, the spatial models frequently used to study land change may restricted by lack of access to public data on land change, faulty sensors, and high levels of variable uncertainty. Thus, models are often only able to make short-term projections, which severely limits the level of prediction they can provide. Additionally, it is difficult to synthesize and combine the case studies of social-environmental systems that are essential to the study of land change on a global scale. Thus, these setbacks pose fundamental challenges to the connection of communities and environment that land change science seeks to achieve.
| Biology and health sciences | Ecology | Biology |
78370587 | https://en.wikipedia.org/wiki/Primary%20vein | Primary vein | A primary vein, also known as the midrib, is the main vascular structure running through the center of a leaf. The primary vein is crucial for the leaf’s efficiency in photosynthesis and overall health, as it ensures the proper flow of materials and structural integrity.
It serves several critical functions, including structural support, as the primary vein helps the leaf maintain its shape and structure; food and water transportation, as it contains xylem and phloem tissues that transport water, minerals, and nutrients to and from the leaf; and connection to the stem, as it links the leaf to its vascular system, facilitating the exchange of materials between the leaf and the rest of the plant. From the primary vein, secondary and tertiary veins branch out, forming a network that distributes resources throughout the leaf.
The arrangement of veins, including the primary vein, varies among plants. Reticulate venation occurs in dicots, where the primary vein branches into a network; parallel venation is found in monocots, where multiple veins run parallel to each other.
| Biology and health sciences | Plant tissues | Biology |
68371541 | https://en.wikipedia.org/wiki/Body%20image%20disturbance | Body image disturbance | Body image disturbance (BID) is a common symptom in patients with eating disorders and is characterized by an altered perception of one's own body.
The onset is mainly attributed to patients with anorexia nervosa who persistently tend to subjectively discern themselves as average or overweight despite adequate, clinical grounds for a classification of being considerably or severely underweight. The symptom is an altered perception of one's body and a severe state of bodily dissatisfaction characterizing the body image disturbance. It is included among the diagnostic criteria for anorexia nervosa in DSM-5 (criterion C).
The disturbance is associated with significant bodily dissatisfaction and is a source of severe distress, often persisting even after seeking treatment for an eating disorder, and is regarded as difficult to treat. Thus, effective body image interventions could improve the prognosis of patients with ED, as experts have suggested. However, there is no hard evidence that current treatments for body image disturbance effectively reduce eating disorder symptoms. Furthermore, pharmacotherapy is ineffective in reducing body misperception and it has been used to focus on correlated psychopathology (e.g., mood or anxiety disorders). However, to date, research and clinicians are developing new therapies such as virtual reality experiences, mirror exposure, or multisensory integration body techniques, which have shown some extent of efficacy.
History
The scientific study of bodily experiences began at the end of the 19th century. German physiologist Hermann Munk was the first to suggest the existence of a cortical representation of the body, supported by his vivisection experiments on the parietal cortex of dogs. A few years later, Carl Wernicke hypothesized a cortical map capable of collecting and processing sensory inputs from every point of the body. In 1905 Bonnier introduced the term body schema, defining it as the mental representation of the body necessary for the brain to perceive objects near, far, or within the body itself.
Bonnier also described three different partial body pattern alterations, (French; 'an overestimation of body size'), ('an underestimation of body size'), and ('a displacement of body parts including internal organs'). Head and Holmes in 1911 expanded the concept of a body schema, introducing the concepts of postural schema and surface schema. They described a patient who could locate the stimuli applied to her body but could not locate her hand in space. They also defined the difference between schema and image. The schema defined as an unconscious representation necessary for movement and localization in space, and the "image" as a conscious body perception.
Therefore, in the history of medicine, distortions in the perception of one's body have mainly occurred in patients with neurological damage or with amputated limbs and a consequence of phantom limb syndrome. In the psychiatric field, the first systematic descriptions of bodily altered perception are already present in Schneider's classification of symptoms of schizophrenia in 1959. The German-American psychiatrist Hilde Bruch was the first physician to describe body image disturbance in eating disorders accurately.
Characteristics
Hilde Bruch first identified and described body image disturbance in anorexia nervosa. In her article "Perceptual and Conceptual Disturbances in Anorexia Nervosa" she wrote:
Body image disturbance is not specific to anorexia nervosa, as it is sometimes present in other eating disorders such as bulimia nervosa and binge eating disorder. Studies published in 2019 on Cortex have shown that it is possible to observe alterations in the perception of one's body in healthy subjects. A slightly altered perception of the body is a normal part of everyone's life and manifests itself more intensely in more vulnerable individuals (e.g., patients with eating disorders). Commonly, body image disturbance is confused with body dysmorphic disorder, an obsessive-compulsive disorder with which it shares some features.
Body image disturbance is a multifaceted construct including both perceptual and attitudinal issues. Some of the more common signs are:
altered body size estimation and altered perception of the body and its shapes;
mental images of one's body appearing distorted or overweight;
frequently third-person mental view of one's body;
negative body-related thoughts;
frequent body-checking behaviors;
frequent comparisons between one's own body and the bodies of others;
emotions of anxiety, shame, and contempt for one's body.
Clinically speaking, a growing body of research suggests that body image disturbance plays a significant role in the onset, maintenance, and relapse of anorexia nervosa, as previously suggested by Bruch in 1962. However, despite increasing evidence, a review by Glashouwer in 2019 stated that the available empirical data are still insufficient and "provide no basis to answer the question whether body image disturbance is a (causal) risk factor for anorexia nervosa". As suggested by the author, this lack of evidence is partly related to terminology problems used in the body image field.
In binge eating disorder
Body image disorder is a characteristic symptom of anorexia nervosa and bulimia nervosa. In both of these disorders, an excessive focus on body shapes and sizes made the body image disturbance easier to identify, to describe, and study. Much less is known about the disorder in patients with binge eating disorder.
As early as 1993, Spitzer compared obese individuals with and without binge eating disorder (BED) and found that those with BED were more frequently concerned about body shape and weight. Additionally, binge eating disorder patients show more significant concerns about weight and body shape, more intense body dissatisfaction, and more frequent avoidance and body checking behaviors. On the other hand, few studies have investigated the altered body perception in patients with binge eating disorder and the results are conflicting. Some patients tend to overestimate their body shapes, in others, they do not. In some cases the perceptual disturbance manifests itself in a paradoxical way, with an underestimation of the real body shapes and sizes. This difference suggests different phenotypes in binge spectrum; hence, a perceptual disturbance can be considered an aggravation of the binge eating disorder, as claimed by Lewer and colleagues in 2017.
Epidemiology
There are no reliable epidemiological data in the literature for body image disturbance.
There are numerous challenges with diagnosis, the most relevant of which is the unclear definition of body image disturbance within official diagnostic manuals such as the DSM and the ICD, which prevents its identification in the population. Further, there are challenges with diagnostic tools, both for recognition and screening. The altered perception of the body can only be measured through behavioral tasks delivered individually (See section below). It cannot be measured with questionnaires, or other tools typically used for broad-spectrum investigations.
As it is not always present in eating disorders, its prevalence is not comparable to that of anorexia nervosa, bulimia nervosa, and binge eating disorder, and cannot be inferred from them. A negative body image may also be present in other psychiatric conditions such as PTSD, major depression, and body dysmorphic disorder. Taken together this data suggests the possible presence of perceptual disturbances in other pathological conditions not directly related to eating disorders. Therefore, the presence of a body image disturbance in other psychiatric diseases remains speculation, not yet supported by sufficient literature data, as suggested by Scheffers.
Definition
DSM-5
Different labels are used in research and clinical settings to describe body image disturbance, generating terminological confusion. Among the most used terms are body image discrepancy, body image self-discrepancy, body image distortion, disturbed body image, disturbances in body estimations, body image disturbance, and negative body image. Sometimes, the term body dissatisfaction is also used to refer to body image disturbance indiscriminately. Moreover, the DSM-5 defines this symptom vaguely: "a disturbance in the way one's body weight or shape is experienced". The lack of a clear definition is problematic from both a clinical and basic research point of view.
Multidimensional
Despite the terminological problems, during the early 2000s numerous scholars agree that body image disturbance is a multidimensional symptom of various components associated with body image. Body image is a concept formed by the interaction of four body-related components: cognitive, affective, behavioral, and perceptual.
Cognitive: thoughts and beliefs about one's body and its shape; a conscious mental representation of the body
Affective: feelings and attitudes related to the body (e.g. bodily satisfaction/dissatisfaction).
Behavioral: the actions that people perform to check on, modify, or hide their body parts.
Perceptual: how the mind senses and perceives the body; it includes proprioceptive, interoceptive, tactile, and visual self-perception.
In people with body image disturbance all of these components are altered at the same time.
In 2021, Artoni et al proposed a clearer definition of body image disturbance as part of a study in Eating and Weight Disorders. The authors suggested using the term bodily dissatisfaction when there are alterations in either the affective, cognitive, or behavioral components of body image and strictly reserving the term body image disturbance only when all four components are altered, including perception. In short, they define body image disturbance as the presence of an altered perception of the shape and weight of one's body, which aggravates body dissatisfaction. The term is consistent with the DSM-5 description "a disturbance in the way weight and body shapes are experienced" and it is therefore "preferable to others".
Components
Cognitive
Patients with body image disturbance exhibit an alteration in how the body's image is stored in their memory—the conscious representation of their bodies. This representation is from a third-person, perspective, more precisely an allocentric representation of the body. This representation is evoked in self-image tasks, such as comparing one's body with others or drawing one's body shapes. However, patients with anorexia nervosa and bulimia nervosa frequently perceive their body as larger than it is in reality.
Patients with anorexia nervosa have negative thoughts about their body, such as "I'm too fat," "I'm ugly," and other negative body-related thoughts. In some cases, however, the ideal internalized body is indicative of unhealthy thinness (e.g., a body without female shapes or one that communicates suffering). An unhealthy body shape could be a critical maintenance factor, generating more attention from family members, reducing the requests and expectations of others, and minimizing sexual attractiveness (especially in patients with sexual trauma).
Affective
Affective components of body image are the feelings and emotions experienced towards one's body. Body dissatisfaction is frequently present in those with body image disturbance, sometimes related to anxiety and shame when the body is exposed or gazed at in a mirror. In some cases, anger and feelings of aggression towards one's body are reported. Fear is associated with thoughts of getting fat.
Congruent with the self-objectification theory, people with body image disturbance frequently experience the body only as an object to be modified rather than as a subject to take care of.
Behavioral
The behavioral component of body image disturbance includes different body-checking behaviors such as repeatedly weighing during the day, spending significant time in front of the mirror or avoiding it, frequently taking selfies, checking parts of the body with hands (e.g. measuring the circumference of the wrists, arms, thighs, belly or hips). Other behaviors include avoiding situations in which the body is exposed (for example, when swimming), and wearing very loose and covering clothes. More generally, avoidance of bodily sensations, particularly the interoceptive ones, is reported.
Perceptual
In body image disturbance, several perceptual domains are altered. Visual perception is the most studied, but research has found misperceptions in other sensory domains such as haptic, tactile, and affective-touch. Also, the body schema is overextended. Some research suggested that this is related to a general enlarged mental representation of body size. A 2017 study published in a companion journal to Nature highlighted how perceptual disturbance is present in those recovered from anorexia nervosa even without affective-cognitive body concerns. Finally, interoception, the sense of the current state of the body, is problematic in those with eating disorders.
Onset
The age of onset for body image disturbance is often early adolescence, the age in which one's comparison to their peers becomes more significant and leads to a greater sensitivity towards criticism of, or teasing about, one's physical appearance. Furthermore, puberty leads to rapid changes in body size and shape that need to be integrated into one's body image. For this reason, adolescence is considered a critical age, with a greater vulnerability to internalizing ideals of thinness, which may ultimately lead to the development of body dissatisfaction, body image disturbance, or eating disorders. In a 2019 review, Sattler and colleagues analyzed eight on-topic studies. The authors found that most adolescents with anorexia nervosa and bulimia nervosa already had body-checking behaviors, negative body-related emotions and feelings, low body satisfaction, and an altered estimate of their body size compared to healthy controls. Unfortunately, exactly how one passes from initial dissatisfaction with one's body to actual perceptual disorder is still unknown despite its clinical importance. The etiopathogenesis is still unknown and the subject of hypotheses in the clinical and neuroscientific fields.
Relationship to other concepts
Body dissatisfaction
Body dissatisfaction and body image disturbance are closely related. Personal, interpersonal, cultural, social, and ethnic variables largely influence bodily dissatisfaction, influencing the emergence of painful feelings towards one's body. In addition, social pressure is considered a risk factor for body dissatisfaction. For example, the frequent presence on media of thin female bodies determines, especially in young girls, a daily comparison between their bodies and models and actresses favoring bodily dissatisfaction; comparing an "ideal" and "real" body feed an intense dissatisfaction with one's body and increases the feeling of shame, disgust, and anxiety towards the one's body and appearance.
Dissatisfaction with one's body involves only three of the four components of the body image. Those with bodily dissatisfaction can have negative thoughts about one's body (e.g., "I'm ugly" or "I'm too short"). In addition, they may have behaviors related to bodily dissatisfaction (e.g., going on a diet or resorting to cosmetic surgery) . They may also have negative feelings of dissatisfaction with their body and be ashamed of showing it in public. However, all these aspects are not enough to define it as a body image disturbance. In fact, there is no perceptual alteration of one's body. Thus, "body image disturbance" cannot be used interchangeably with "body dissatisfaction", but they are closely related.
Body dysmorphic disorder
Body image disturbance in anorexia and body dysmorphic disorder (BDD) are similar psychiatric conditions that both involve an altered perception of the body or parts of it but are not the same disorder. Body image disturbance is a symptom of anorexia nervosa (AN) and is present as criterion C in the DSM-5, and alters the perception of weight and shapes of the whole body. Patients with anorexia nervosa believe that they are overweight, perceive their body as being "fat" and misperceive their body's shape. Body dysmorphic disorder, meanwhile, is an obsessive-compulsive disorder characterized by disproportionate concern for minimal or absent individual bodily flaws, which cause personal distress and social impairment—patients with body dysmorphic disorder are concerned about physical details, mainly the face, skin, and nose. Thus, both anorexia nervosa and body dysmorphic disorder manifest significant disturbances in body image but are different and highly comorbid. For example, Grant et al reported that 39% of AN patients in their sample had a comorbid diagnosis of body dysmorphic disorder, with concerns unrelated to weight. Cerea et al reported that 26% of their AN sample had a probable BDD diagnosis with non-weight-related body concerns.
While a 2019 review by Phillipou et al in Psychiatry Research suggested that the two disorders could be taken together as "body image disturbances", plural, more in-depth studies are needed to confirm this new classification hypothesis.
Similarities
Previous studies found that both BDD and eating disorder groups were similar in body dissatisfaction, body checking, body concerns, and levels of perfectionism. Furthermore, both BDD and AN patients report higher intensities of negative emotions, lower intensities of positive emotions, lower self-esteem, and anxiety symptoms. Moreover, research find severe concerns about one's appearance, leading to a continuous confrontation with others' bodies in both diseases. In addition, body image disturbances and body dysmorphic disorder generally onset during adolescence. Finally, alterations in visual processes seems to be present in both disorders, with greater attention to detail, but with greater difficulty in perceiving stimuli holistically. Indeed, neurophysiology and neuroimaging research suggests similarities between BDD and AN patients in terms of abnormalities in visuospatial processing.
Differences
Despite many similarities, the two disorders also have significant differences. The first is gender distribution. Body image disturbance is much more present in females, unlike BDD, which has a much less unbalanced incidence. Furthermore, those with dysmorphophobia tend to have more significant inhibitions and avoidance of social activities than those with anorexia nervosa. Differences are self-evident when considering the focus of physical concerns and misperception in AN and BDD. BDD patients report concerns and misperception in specific body areas (mainly face, skin, and hair). In patients with AN, the altered perception could involve the arms, shoulders, thighs, abdomen, hips, and breasts, and concerns are about overall body shape and weight; thus leading to an alteration of the entire explicit (body image) and implicit (body schema) mental representation of the body. Furthermore, in anorexia nervosa, not only is visual perception of one's body altered, but both tactile and interoceptive perception are as well.
Diagnosis
Body image disturbance is not yet clearly defined by official disease classifications. However, it appears in the DSM-5 under criterion C for anorexia nervosa and is vaguely described as "a disturbance in the way weight and body shapes are experienced". As a result, diagnosis is usually based on reported signs and symptoms; there are still no biological markers for body image disturbance. Numerous psychometric instruments to measure the cognitive, affective, and behavioral components of one's body image are used in clinical and research settings, helping in assessing the body image's attitudinal components. Recently, research developed other instruments to measure the perceptive component.
Attitudinal assessment tools
The Eating Disorder Inventory 3 (EDI-3) represents an improvement of the earlier versions of the EDI, a self-report questionnaire widely used both in research and clinical settings. It consists of 91 questions, and items are rated on a six-point Likert scale (always, usually, sometimes, rarely, never), with higher scores representing more severe symptoms. Precisely, the BD subscale of EDI-3 measures bodily dissatisfaction.
The Body Uneasiness Test (BUT) is a self-administered questionnaire. It explores several areas in clinical and non-clinical populations: weight phobia, body image-related avoidance behavior, compulsive self-monitoring, detachment and estrangement feelings toward one's own body. Besides, explore specific worries about particular body parts, shapes, or functions. Higher scores indicate significant body uneasiness.
The Body Image Disturbance Questionnaire investigates different areas related to body image disturbance. For example, it evaluates the parts of the body an individual finds most problematic, the psychological effects of their worries about their body, and effects on their social life and eating behavior.
The Body Shape Questionnaire is a 34-item self-assessment questionnaire designed to measure the degree of dissatisfaction with the weight and shape of one's body. It includes questions about the fear of weight gain and about whether one has the urge or desire to lose weight.
The Body Checking Questionnaire measures the frequency of body control behaviors, such as measuring specific body areas, using mirrors to check or avoid body shape, wearing loose-fitting, covering clothing, or checking for bony prominence with one's hands. Higher scores indicate a higher frequency of body checking behaviors.
Perceptual assessment tools
BID-CA (Test for Body Image Distortion in Children and Adolescents): Patients with a 180 cm rope simulate the circumference of the different parts of the body, including the hips, thighs, shoulder width and other parts of the body considered phobic. This estimate is compared to the actual patient size. The procedure is validated for children and adolescents but can also be used in adults.
Visual Size Estimation Task (VSE): patients are placed standing in front of a wall at a distance of about one meter. They place two stickers on the wall that reflect the perceived dimensions of different body parts, such as the width of the shoulders, hips, or waistline. These values are then taken and compared with those measured directly on the patient.
Tactile Estimation Task (TET): a standard gauge is used for measurement. During the measurement, patients estimate the distance between the two points of the gauge while it is placed on different parts of the body. Several measurements are made and the gauge is oriented in different directions (for example, at the height of the hips, it is placed both horizontally and vertically)
3D Morphing: Numerous 3D modeling computer programs allow directly modifying a human body model by increasing or decreasing its size. Patients modify the 3D avatar so that it represents their body image as closely as possible. The model values are then compared with the actual measurements of the patients.
Multi-sensory perception
The perception of one's body is a multi-sensory process that integrates information deriving from different sensory cortices, including the visual, proprioceptive, tactile, interoceptive, and auditory-vestibular areas. All of these areas are involved in the perception of one's body. An important component is the premotor cortex (PMC) and the intraparietal sulcus. These two areas are active during illusory hand perception tasks in both hemispheres.
The somatosensory areas are also involved, in particular the primary somatosensory cortex (S1). An important area is the extrastriate body area located rostrocaudally in the occipital lobe and is specific to human bodies perception. Two other areas of considerable importance in the perception of the body are the insula and the anterior cingulate cortex. The insular cortex is fundamental in the direct perception and integration of bodily signals from different cortical areas and, despite being an area historically delegated to the sole function of perceiving the state of internal organs as proposed by Sherrington in 1911, research advances demonstrate the central role of the insula in several domains, including the recognition that one's body belongs to us. Namely the "body ownership".
Brain imaging
fMRI studies examining brain responses in anorexia nervosa patients to paradigms that include body image tasks have found altered activation across different brain areas, including the prefrontal cortex, precuneus, parietal cortex, insula, amygdala, ventral striatum, extrastriate body area, and fusiform gyrus. However, as Janet Treasure commented, "the research [in the field] is fragmented, and the mechanism of how these areas map onto the functional networks described above needs further study ... the mechanism by which the extremes of body distortion are driven and [their] circuitry is not known yet."
Prevention
The Body Project is an eating disorder prevention program within a dissonant-cognitive framework. The program provides a forum for high school girls and college-age women to confront unrealistic-looking ideals and develop a healthy body image and self-esteem. It has been repeatedly shown to effectively reduce body dissatisfaction, negative mood, unhealthy diet, and disordered eating.
Treatments
Of cognition, affect, and behavior
Historically, research and clinicians have mainly focused on body image disturbance's cognitive, affective, and behavioral components. Consequently, treatments generally target symptoms such as body checking, dysfunctional beliefs, feelings, and emotions relating to the body. One of the best-known psychotherapies in the field is CBT-E. CBT-E is a cognitive-behavioral therapy that has been enhanced with particular strategies to address the psychopathology of eating disorders. These include reducing negative thoughts and worries about body weight and shape, reducing clinical perfectionism, and body-checking behavior. In 2020 a review has shown that CBT-E effectively reduces core symptoms in eating disorders, including concerns about the body. Despite this, the results of CBT-E are no better than other forms of treatment. A therapy of choice for eating disorders in adults has not yet been identified.
Additionally, two other noteworthy body image treatments are Thomas F. Cash's "Body Image Workbook" and BodyWise. The former is an 8-step group treatment within a classic cognitive-behavioral framework. The latter is a psychoeducational-based treatment improved with cognitive remediation techniques to promote awareness of body image difficulties and to reduce cognitive inflexibility and body dissatisfaction.
Of perception
Compared to the classic cognitive-behavioral therapeutic paradigms, since the early 2000s, new treatments for body image disturbance have been developed focusing on the disorder's perceptual component. Mirror Exposure is a new cognitive-behavioral technique that aims to reduce experiential avoidance, reduce bodily dissatisfaction, and improve one's misperception of one's body. During the exposure therapy, patients are invited to observe themselves in front of a large full-length mirror. There are different types of mirror exposure: guided exposure; unguided exposure; exposure with mindfulness exercises; and cognitive dissonance-based mirror exposure. To date, few studies have investigated the effects of mirror exposure in patients with body image disturbance. In the International Journal of Eating Disorders, Key et al (2002) conducted a non-randomized trial in a clinical sample and compared a body image group therapy with or without mirror exposure. They found a significant improvement in body dissatisfaction only in the mirror exposure therapy group. Despite the positive evidence, in 2018, a review in Clinical Psychology Review suggests that Mirror Exposure has a low-to-medium effect in reducing body image disturbance and further studies are needed to improve it.
Another treatment for body image disturbance is Virtual Reality (VR) Body Swapping. VR-Body Swapping is a technique that allows generating a body illusion during a virtual reality experience. Specifically, after building a virtual avatar using 3D modeling software, it is possible to generate the illusion that the avatar's body is one's own body. The avatar is a 3D human body model that simulates the actual size of the patient and can be modified directly. Some studies have found that applying this technique to those with anorexia nervosa reduces their misperception of their bodies but provides, at the moment, only a short-term effect.
However, other treatments have also been developed to integrate tactile, proprioceptive, and interoceptive perception into one's overall body perception. Hoop Training is a short-term 8-week intervention (10 minutes per session) designed to become aware of and reduce body misperception. During the exercise, several flexible circles of different sizes are placed in front of the patient. First, the patients indicate which of the different circles best fits the circumference of their hips. Once indicated, patients are invited to enter the circle and, raising it, underestimating whether their estimate was accurate or not. The exercise takes place until the patient identifies the correct circumference for her hips. The circle chosen initially can be compared with the one that can coincide with the actual size of the patient. Hoop Training is meant to work on the components cognitive, affective, and perceptive of body image disturbance and the first efficacy data were published in 2019.
Another perceptive treatment is the Body Perception Treatment (BPT) whose first efficacy data were published in 2021. BPT is a specific group intervention for body image disturbance focused on tactile, proprioceptive, and interoceptive self-perceptions during a body-focused experience. During the exercise, patients lie down on their backs in the supine position with closed eyes. Then the therapist guide patients to selectively focus attention on the different body parts in contact with the floor. In order: feet, calves, thighs, back, shoulders, hands, arms, head and the body in its entirety. In addition, patients are invited to pay attention to skin temperature, heart beat and flow of breath. The treatment is consistent with the hypothesized role of interoception in developing body image disturbance by Badoud and Tsakiris in 2017.
Both Hoop Training and Body Perception Treatment showed effective results in pilot studies and were designed to work within a multisensory integration framework. However, they complement, not replace, current standard therapies for eating disorders. However, both are also novelty treatments, and the results have not been replicated in independent studies. Thus, their actual effectiveness will have to be confirmed/disconfirmed by future research. As of the end of 2021 they have not yet been replicated.
| Biology and health sciences | Mental disorders | Health |
69898377 | https://en.wikipedia.org/wiki/Natural%20hydrogen | Natural hydrogen | Natural hydrogen (known as white hydrogen, geologic hydrogen, geogenic hydrogen, or gold hydrogen) is molecular hydrogen present on Earth that is formed by natural processes (as opposed to hydrogen produced in a laboratory or in industry). A closely related artificially produced form of hydrogen is green hydrogen which is produced from renewable energy sources such as wind or solar energy. Non-renewable forms of hydrogen include grey, brown, blue or black hydrogen which are obtained from the processing of fossil fuels.
Natural hydrogen is believed to exist in economically viable concentrations and locations on every continent. Natural hydrogen may be capable of supplying mankind's "projected global hydrogen demand for thousands of years," is non-polluting, may be available at significantly lower end user costs per therm than industrial hydrogen, and may be renewable. Natural hydrogen has been identified in many source rocks in areas beyond the sedimentary basins where oil companies typically operate.
History
In Adelaide, Australia in the 1930s, oil well drillers reported finding "vast amounts of high-purity hydrogen." At the time it was viewed as a useless byproduct of the oil drilling industry, and no efforts were made to capture it.
In 1987 in the village of Bourakebougou in Mali, Africa, a worker attempted to light his cigarette next to a certain water well, and the well unexpectedly caught fire. A local entrepreneur soon became interested in the possible economic value of this "burning well" and determined that the flames were produced by natural hydrogen seeping out of the well. A local petroleum company was soon hired to harvest and sell the hydrogen, and as of 2024, the villagers of Bourakébougou village continue to pay for their hydrogen. the Malian hydrogen well remains as the world’s first and only economically successful hydrogen well.
During the 2020s, interest in natural hydrogen has increased and investments have been made to develop natural hydrogen wells in the US, France and Australia. In France, one petroleum company, Française De l’Énergie, has said that it aims to begin extracting hydrogen by 2027 or 2028.
Natural hydrogen sources
Sources of natural hydrogen include:
degassing of deep hydrogen from Earth's crust and mantle;
reaction of water with ultrabasic rocks (serpentinisation);
water in contact with reducing agents in Earth's mantle;
weathering – water in contact with freshly exposed rock surfaces;
decomposition of hydroxyl ions in the structure of minerals;
natural water radiolysis;
decomposition of organic matter;
biological activity
Serpentinization is thought to produce approximately 80% of the world's hydrogen, especially as seawater interacts with iron- and magnesium-rich (ultramafic) igneous rocks in the ocean floor. Current models point towards radiolysis as the source of most other natural hydrogen.
Resources and reserves
According to the Financial Times, there are 5 trillion tons of natural hydrogen resources worldwide. Most of this hydrogen is likely dispersed too widely to be economically recoverable, but the U.S. Geological Survey has reported that even a fractional recovery could meet global demand for hundreds of years. A discovery in Russia in 2008 suggests the possibility of extracting native hydrogen in geological environments. Resources have been identified in France, Mali, the United States, and approximately a dozen other countries.
In 2023 Pironon and de Donato announced the discovery of a deposit they estimated to be some 46 million to 260 million metric tons (several years worth of 2020s production). In 2024, a natural deposit of helium and hydrogen was discovered in Rukwa, Tanzania., as well in Bulqizë, Albania.
Midcontinent Rift System
White hydrogen could be found or produced in the Mid-continental Rift System at scale. Water could be pumped down to hot iron-rich rock to produce hydrogen for extraction. Dissolving carbon dioxide in these fluids could allow for simultaneous carbon sequestration through carbonation of the rocks. The resulting hydrogen would be produced through a carbon-negative pathway and has been referred to as "orange" hydrogen.
Geology
Natural hydrogen is generated from various sources. Many hydrogen emergences have been identified on mid-ocean ridges. Serpentinisation occurs frequently in the oceanic crust; many targets for exploration include portions of oceanic crust (ophiolites) which have been obducted and incorporated into continental crust. Aulacogens such as the Midcontinent Rift System of North America are also viable sources of rocks which may undergo serpentinisation.
Diagenetic origin (iron oxidation) in the sedimentary basins of cratons, notably are found in Russia.
Mantle hydrogen and hydrogen from radiolysis (natural electrolysis) or from bacterial activity are under investigation. In France, the Alps and Pyrenees are suitable for exploitation. New Caledonia has hyperalkaline sources that show hydrogen emissions.
Hydrogen is soluble in fresh water, especially at moderate depths as solubility generally increases with pressure. However, at greater depths and pressures, such as within the mantle, the solubility decreases due to the highly asymmetric nature of mixtures of hydrogen and water.
Literature
Vladimir Vernadsky originated the concept of natural hydrogen captured by the Earth in the process of formation from the post-nebula cloud. Cosmogonical aspects were anticipated by Fred Hoyle. From 1960–2010, V.N. Larin developed the Primordially Hydridic Earth concept that described deep-seated natural hydrogen prominence and migration paths.
| Physical sciences | Geochemistry | Earth science |
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